POWER REDUNDANCY IS ESSENTIAL FOR BEV SAFETY, RELIABILITY High-efficiency power modules convert dual 400V batteries down to loads ISSUE 1 – Feb/March 2024 www.power-mag.com Also inside this issue Market News | Power Supply Design Telecomms Power | Automotive Power Microcontroller Design | Sensor Technology Supercapacitors | Product Update | Web Locator
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CONTENTS www.power-mag.com Issue 1 2024 Power Electronics Europe 3 Publisher Ian Atkinson Tel: +44 (0)1732 370340 Email: ian@dfamedia.co.uk www.power-mag.com Production Editor Chris Davis Tel: +44 (0)1732 370340 Email: chris@dfamedia.co.uk Financial Manager Joanne Morgan Tel: +44 (0)1732 370340 Email: accounts@dfamedia.co.uk Reader/Circulation Enquiries Perception Tel: +44 (0) 1825 701520 Email: dfamedia@dmags.co.uk INTERNATIONAL SALES OFFICES Mainland Europe: Victoria Hufmann Norbert Hufmann Tel: +49 911 9397 643 Fax: +49 911 9397 6459 Email: pee@hufmann.info Eastern US Ian Atkinson Tel: +44 (0)1732 370340 Email: ian@dfamedia.co.uk Western US and Canada Ian Atkinson Tel: +44 (0)1732 370340 Email: ian@dfamedia.co.uk Japan: Yoshinori Ikeda, Pacific Business Inc Tel: 81-(0)3-3661-6138 Fax: 81-(0)3-3661-6139 Email: pbi2010@gol.com Taiwan Prisco Ind. Service Corp. Tel: 886 2 2322 5266 Fax: 886 2 2322 2205 Circulation and subscription: Power Electronics Europe is available for the following subscription charges. Power Electronics Europe: annual charge UK/NI £95, overseas $160, EUR 150. Contact: DFA Manufacturing Media, 192 High Street, Tonbridge, Kent TN9 1BE Great Britain. Tel: +44 (0)1732 370340. Refunds on cancelled subscriptions will only be provided at the Publisher’s discretion, unless specifically guaranteed within the terms of subscription offer. Editorial information should be sent to The Editor, Power Electronics Europe, 192 High Street, Tonbridge TN9 1BE U.K. The contents of Power Electronics Europe are subject to reproduction in information storage and retrieval systems. All rights reserved. No part of this publication may be reproduced in any form or by any means, electronic or mechanical including photocopying, recording or any information storage or retrieval system without the express prior written consent of the publisher. Printed by: Warners. ISSN 1748-3530 PAGE 4 Market News PEE looks at the latest Market News and company developments PAGE 13 The role of voltage supervisors for system power reliability Voltage supervisors add reliability by monitoring the power supply failures and putting a microcontroller in reset mode to prevent system error and malfunction. By Noel Tenorio, Product Applications Engineer, Analog Devices PAGE 16 Power choices to minimise maintenance The choice of power source can reduce telecomms maintenance cost. By Andy Brown, Director, Technical Marketing DC/DC, Advanced Energy Industries PAGE 18 Why EVs don’t need 12V lead acid batteries The continuous advancement of lithium-ion battery technology has given EVs longer driving range, faster acceleration and more horsepower than ever before. So why are most EVs still carrying a 12V lead acid battery for standby power? By Power Integrations PAGE 21 The art of noise: how to design to minimise interference In a perfect world, signal margins and power supply voltages are maintained for a safe, stable environment, says Graeme Clark, Principal Engineer, Renesas Electronics PAGE 24 Making sense of the world around us with sensor ICs How accurate sensing enables better system performance and increased efficiency. By Giovanni Campanella, Sector General Manager, Industrial Systems at Texas Instruments PAGE 27 Characteristics that boost a supercapacitor’s power There are many uses for supercapacitors beyond emergency power supplies, explains Dr René Kalbitz, Product Manager Capacitors & Resistors Division at Würth Elektronik eiSos GmbH PAGE 30 Products PAGE 34 Web Locator BEV advancements are driving sales, but vehicle safety and reliability will ensure long-term viability Innovative power architectures using power modules provide power redundancy and improve overall safety and system performance. More details on page 10. FEATURE STORY Subscribe for your FREE copy now
4 MARKET NEWS Issue 1 2024 Power Electronics Europe www.power-mag.com PCIM Europe 2024’s exhibition space grows with an extra hall Increased demand from exhibiting companies means that PCIM Europe 2024 has expanded beyond halls 6, 7 and 9. An extra hall will be allocated for the exhibition and conference, which takes place between 11 to 13 June 2024 at the Nuremberg Exhibition Center, Nuremberg, Germany. The additional hall reflects this increasing demand for opportunities for suppliers to present and exchange information and technology developments, says Messe Messago. PCIM Europe has been a platform for the power electronics community for 43 years and today reflects changes as the industry adapts to develop reliable energy supplies for new applications, such as electro mobility. The extra space will support the event’s continuous growth, increase the variety of products and services presented, and drive further development of power electronics, says the show organiser. The organiser says that visitors to PCIM Europe can look forward to an even more extensive range of products and services as well as further networking opportunities. The number of registered exhibiting companies is expected to be another record number, already surpassing 450 by the end of last year. “We are aiming to respond to the needs of the industry in a timely manner and thus significantly increase product diversity and networking opportunities,” explains Lisette Hausser, Vice President PCIM Europe at organiser Mesago Messe Frankfurt GmbH. A new focus for 2024 is smart power system integration. Miniaturisation and complexity in the electronics industry is leading to constantly increasing requirements in terms of power density, efficiency, signal frequencies and thermal properties, meaning that system integration occupies centre stage, with consequent demands on materials, components, circuit carriers, temperature resistance and, especially assembly and interconnection technologies. At the Smart Power System Integration Zone and Stage in Hall 5, exhibiting companies will present innovative technologies, solutions, and application examples for current and future challenges in power electronics manufacturing, particularly for applications in areas such as automotive, railway and server technology. For the first time, there will be an extensive programme of presentations on current products and trends on four stages. Each will have a different focus: the Smart Power System Integration Stage, Technology Stage, formerly known as the Industry Stage, Exhibitor Stage and EMobility & Energy Storage Stage. There will be a special E-Mobility & Energy Storage Zone with its own stage which will host presentations on current topics and trends relating to the electromobility and energy storage value chain. In addition, live product demos will take place at the stands of suppliers from this area. Electromobility and energy storage will also be addressed at the parallel conference in the form of presentations. The 2024 conference received a record number of submissions, with presentations from the R&D departments of leading companies and universities from all areas of power electronics. The 2024 conference programme can be found at www.pcim-europe.com
MARKET NEWS 5 www.power-mag.com Issue 1 2024 Power Electronics Europe Arrow Electronics staffs High-Power Centre of Excellence with eInfochip The centre at the company’s Swindon facility in the UK will assist customers develop high-power solutions, a critical component in advancing electrification and sustainability initiatives. High-power designs are essential for energy efficiency in net-zero projects such as electric vehicles, renewable energy, battery storage and grid infrastructure, for example. Challenges include a lack of power expertise, stringent functional safety and reliability requirements, intricate PCB layout and the necessity for costly testing equipment, explains the company. The High-Power CoE is equipped with a highpower lab and an experienced engineering team from eInfochips. The goal is to empower innovators to navigate the complexities of highpower electronics design effectively, says the company. “The Swindon facility is known for its configurable power supply capabilities, and the CoE builds on its legacy by investing in new equipment and engineering talent. We can now offer turnkey design services from the Swindon facility,” says Murdoch Fitzgerald, vice president, global engineering and design services at Arrow Electronics. The CoE will design products for all customers of Arrow and its subsidiaries, such as Richardson RFPD, supporting customers in planning and managing high-power product roadmap and lifecycles. https://www.einfochips.com/high-powercentre-of-excellence/. A lab to develop and test microelectronic circuits for quantum computers and develop AI algorithms for the early detection of variances in power systems, has been opened by Infineon. The lab in Oberhaching near Munich will use AI to simulate and better predict the ageing and failure characteristics of microelectronics in the power market. It will develop the necessary algorithms and introduce practical measurements to establish the data basis for training neural networks and verifying behaviour. This will help better estimate the service life of power converters and will aid in detection of anomalies. The insights will contribute to proactive maintenance to prevent equipment failure. It will also focus on ensuring microcircuits are stable and small in size, reliable and can be produced on an industrial scale. Approximately 20 researchers will work at the lab. “Infineon plans to reinvent the core element of the quantum computer. One of the central tasks of the new quantum laboratory will be to develop and test electronic systems for ion trap quantum computing with the objective of integrating these systems in the Quantum Processing Unit,” says Richard Kuncic, Senior Vice President and General Manager Power Systems at Infineon Technologies. A cryostat has been installed, which can maintain cryogenic temperatures as low as 4°K (- 269°C) for qubits, the smallest units for calculations with quantum computers. These are extremely sensitive and only adequately stable under extreme conditions, typically temperatures below -250°C, and at the lowest possible pressures. At the same time, electronic systems have to keep working in these extreme conditions, when many materials change their properties, including their electric behaviour. Pictured from left to right: Chuck Spinner, Head of Central R&D Power Systems and Solutions (PSS); Hartmut Hiller, Head of R&D; Adam White, President Power Systems and Solutions; Richard Kuncic, Head of Power Systems). http://www.infineon.com Lab is dedicated to quantum electronics and power AI
6 MARKET NEWS Issue 1 2024 Power Electronics Europe www.power-mag.com DigiKey signs global partnership with Ambiq Low power IC supplier, Ambiq, has signed a global distribution deal with DigiKey which now stocks Apollo4 Blue Plus. The distributor stocks Ambiq’s low power ICs, including the latest SoC, the Apollo4 Blue Plus which combines Bluetooth Low Energy, graphics and audio for always-connected IoT endpoints. It is claimed to have one of the lowest dynamic powers for microcontrollers currently available making it suitable for wearables and battery-operated smart devices. The Apollo4 Blue Plus is a 4th generation system processor solution built upon Ambiq’s proprietary Subthreshold Power-Optimized Technology (SPOT) platform. The hardware and software solution enables current and future battery-powered endpoint devices to achieve a higher level of intelligence without sacrificing battery life, says the company. It has sufficient compute and storage to handle complex AI algorithms and neural networks, always-on voice recognition, and display capability for smooth graphics. “DigiKey is pleased to add Ambiq to our core supplier line card,” said David Stein, vice president, semiconductors at DigiKey. He believes that Ambiq has raised the bar with this new MCU and SoC. “We’re excited to support designers, engineers and builders globally as they work with these innovative solutions to accelerate progress,” he says. https://www.digikey.com/en/product-highlight/a/ambiq/apollo4blue-plus-soc/?utm_source=referral&utm_ medium=pressrelease&utm_campaign=pressrelease Nexperia and Mitsubishi Electric to develop joint SiC MOSFETs A strategic partnership between Nexperia and Mitsubishi Electric to jointly develop SiC MOSFETs has been announced. It brings Mitsubishi Electric’s power semiconductor portfolio and SiC modules, which are used in Japan’s high speed Shinkansen trains, with Nxperia’s wide bandgap device technology and discrete packaging experience to develop SiC wide bandgap semiconductors. Nexperia’s headquarters are in the Netherlands, with employees across Europe, Asia and the USA. It designs and builds components for “virtually every commercial electronic design in the world”, from automotive and industrial to mobile and consumer applications. Mitsubishi Electric is based in Tokyo, Japan and manufactures electrical and electronic equipment used in information processing and communications, space development and satellite communications, consumer electronics, industrial technology, energy, transportation and building equipment. The Japan-Euro partnership was welcomed by Mark Roeloffzen, SVP and General Manager Business Group Bipolar Discretes at Nexperia. “This mutually beneficial strategic partnership . . . represents a significant stride in Nexperia’s silicon carbide journey,” he said. Combining Mitsubishi Electric’s expertise in supplying technically proven SiC devices and modules with Nexperia’s expertise in discrete products and packaging generate positive synergies between both companies - ultimately enabling our customers to deliver highly energy efficient products in the industrial, automotive or consumer markets they serve”. Dr. Masayoshi Takemi, Executive Officer, Group President, Semiconductor and Device of Mitsubishi Electric, added: “We are delighted to have reached an agreement on a partnership for joint development that leverages the semiconductor technologies of both companies.” https://www.nexperia.com Integrating onsemi’s Hyperlux image sensor on Renesas’ R-Car V4x for automotive vision systems to OEMs and Tier 1s. In a strategic collaboration, the image sensor has been integrated to the R-Car V4x SoC family in an effort to develop the safety of semi-automated vehicles. The 2.1µm pixel size image sensor has 150dB high dynamic range (HDR) and LED flicker mitigation (LFM) across the full automotive temperature range. Combined with the R-Car software platform, the partners say that OEMs and Tier 1s. can access automotive computing for applications including ADAS and up to Level 3 automated driving. Takeshi Fuse, Head of Function Unit and onsemi and Renesas collaborate for safe, semi-automated driving
microchip.com/SiC The Microchip name and logo and the Microchip logo are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. All other trademarks are the property of their registered owners. © 2023 Microchip Technology Inc. All rights reserved. MEC2510A-UK-07-23 Empowering E-Mobility With Silicon Carbide Adopt SiC With Ease, Speed and Confidence Shape the future of e-mobility with Microchip’s Silicon Carbide (SiC) technology. Our solutions make it easy to keep pace with the rapid advancements in Electric Vehicle (EV) designs, allowing you to develop innovative applications that are more efficient, compact and robust than ever before. Our unrivaled technical support spans Microchip’s diverse product portfolio to quickly provide SiC-based system solutions tailored to your application’s needs while minimizing system cost, time to market and risk. Learn how we can help you adopt SiC into your EV designs with ease, speed and confidence.
8 MARKET NEWS Issue 1 2024 Power Electronics Europe www.power-mag.com Business Development for the High Performance Computing, Analog and Power Solutions Group at Renesas, says: “Out-ofthe-box compatibility of the onsemi Hyperlux image sensors on our R-Car V4x platform and continued collaboration on the next generation offerings are testament to the quality of our products and longstanding relationship.” The two companies’ products have been deployed together in automotive applications for many years and product generations, says onsemi. Millions of vehicles on the road today are using a combination of R-Car Gen2 or Gen3 with onsemi image sensors in applications such as front camera, surround view and driver monitoring systems. “The decision to integrate Hyperlux image sensors onto Renesas’ latest platform demonstrates that our sensors are a key technology for safety-critical ADAS and autonomous driving solutions, delivering the uncompromised image quality that customers expect,” comments Chris Adams, vice president, Automotive Sensing Division at onsemi. https://www.onsemi.com/solutions/techn ology/hyperlux Infineon Technologies has closed the acquisition of GaN Systems, acquiring its portfolio of GaN-based power conversion products. On 2 March 2023, Infineon and GaN Systems announced that the companies had signed a definitive agreement under which Infineon would acquire GaN Systems for US$830 million. All required regulatory clearances have now been obtained and the all-cash acquisition was funded from existing liquidity. “GaN technology is paving the way for more energy-efficient and CO 2-saving solutions that support decarbonisation,” says Jochen Hanebeck (pictured), CEO of Infineon. He believes the acquisition “significantly accelerates our GaN roadmap”. With the acquisition of the Ottawa-based company, Infineon now has a total of 450 GaN experts and more than 350 GaN patent families. Both companies’ complementary strengths in IP and application understanding as well as a wellfilled customer project pipeline put Infineon in an excellent position to address various fast-growth applications, says the company. Infineon Technologies’ revenue in the fiscal year ending 30 September 2022 was €14.2 billion. https://www.infineon.com/ Infineon completes acquisition of GaN Systems An integrated approach for X-Fab Silicon Foundries’ XA035 process brings galvanic isolation elements directly together with active circuits Building on the company’s advanced process optimised for robust discrete capacitive or inductive couplers, existing galvanic isolation elements can be brought directly together with active circuits. This integrated approach allows more flexibility in the design of isolation products, says the company and addresses emerging opportunities in renewable energy, EV powertrains, factory automation and industrial power. Based on a 350nm process node, XA035 is suitable for the fabrication of automotive sensors and high voltage industrial devices. The high voltage signal isolation capabilities it now supports mean long term operational performance is maintained, even in demanding environments, says X-Fab. It will enable the manufacture of robust components that are AEC-Q100 Grade 0compliant and industrial-rated, such as digital isolators, isolated gate drivers and isolated amplifier ICs. X-Fab provides a comprehensive PDK (process development kit) that supports the new process technology for all major EDA vendors. “We see a growing demand from our customers for robust foundry solutions to design galvanically isolated products. X-Fab has been in production for several years with its proven high-reliable isolation layer for discrete coupler implementations,” says Tilman Metzger, Marketing Manager for HighVoltage Products at X-Fab. “By leveraging the very same process module, we are now able to offer even more flexibility in designing such products by enabling the direct integration with CMOS circuits on the same die. We are also excited to see the first integrated customer products nearing production.” http://www.xfab.com. Foundry adds CMOS integration to its galvanic isolation technology
www.apec-conf.org
10 AUTOMOTIVE POWER www.vicorpower.com Issue 1 2024 Power Electronics Europe www.power-mag.com BEV advancements are driving sales, but vehicle safety and reliability will ensure long-term viability Innovative power architectures using power modules provide power redundancy and improve overall safety and system performance By Patrick Kowalyk, Automotive FAE, Vicor Sales of electric vehicles continue to grow globally. March 2023 saw combined (BEV and PHEV) sales of over 322,000 plug-in electric vehicles registered across Europe, a 29% year-on-year increase. Furthermore, battery electric vehicles show a 44% year-on-year increase and account for a 16% share of all cars sold in Europe.1 These figures are good news for all vehicle manufacturers after the dismal car sales during the 2020-2021 COVID-19 period. The rebound in overall sales and the significant rise in EV sales bodes well for the future. Still there remains consumer reticence around charging infrastructure and battery range. In response, manufacturers already have secondgeneration EV models in production addressing consumer concerns. Trends shaping the second generation of electric vehicles There are several trends worth noting. 1. Improving charging time and reducing vehicle weight. Weight directly influences an EV’s range. Therefore, anything that reduces vehicle weight increases the payload and its maximum range. 2. Removing the traditional 12V DC primary battery offers significant weight advantages. Today reducing its size or removing it altogether are options. 3. Migrating to a 48V zonal networking architecture reduces the need for bulky, heavy and costly 4 gauge wire harnesses. Similarly, the move to a 48V architecture for secondary equipment (heated seats, seat movers, etc.) also benefits from reducing cable size and weight. 4. Upgrading from 400V to 800V battery voltage is being quickly adopted. This trend enables reduced cable weight and charging time but requires upgrading the charging post infrastructure to support both voltages. Still, there are other important safety and reliability enhancements needed. There is no escaping the fact that since a BEV derives all its power from a single source— the high-voltage traction battery— any interruption to it is more than inconvenient, it can pose serious safety hazards. So while creature comforts may be captivating consumers and stimulating new sales today, long term viability of the EV platform is dependent on sound safety protocols being designed into the vehicle. In an all-electric automobile power redundancy is essential. Designing-in power redundancy is essential to safety and reliability The addition of a redundant source of energy in an EV ensures safety and reliability for its driver, passengers and other road users. Redundant power is required for three load types: Steering, braking and safety sensor systems Always-on vehicle network (CAN bus, Ethernet, etc.) communication Non-essential loads that can be turned off during critical power situations For example, EV power architects could achieve an 800V traction battery source by connecting two 400V battery packs in series, with each battery configuration having a separate DC-DC (400V to 800V) converter. This configuration (Figure 1) is called a Dual-400V series-stacked system. Some manufacturers are presently using the Dual-400V series-stacked system for several reasons. The primary reason is that charging with a 400V charger is easier because many installed public chargers are not 800V compatible. Today, as new chargers are installed, they can support both 400V and 800V batteries. The second reason is that if a manufacturer has already designed and qualified a 400V battery pack, it is faster and easier to add two packs in series. Another approach is the Dual 800V parallel battery configuration (Figure 2) that involves using two 800V batteries in parallel. Again, two separate DC-DC converters provide redundancy. There are trade-offs with both configurations. When using a Dual-400V series-stacked system these are the drawbacks to consider: The 400V DC-DC converters need more clearance to chassis ground as the topmost DC-DC converter is at 800V. The center tap between the two 400V Figure 1 — Dual-400V series-stacked system Connecting two 400V battery packs in series with separate DC-DC converters in a stacked architecture allows lower-voltage operation and splitting the load to two or more strings (Source: Vicor)
www.vicorpower.com AUTOMOTIVE POWER 11 www.power-mag.com Issue 1 2024 Power Electronics Europe battery packs needs to be accessible on the high voltage connector. An imbalance of two series connected 400V battery packs may cause the regulator to enter in an overvoltage protection mode condition, interrupting the power supply period. The advantages of the system are: If one string fails, the other string will pick up the load. The components of the system have lower voltage ratings and are therefore less expensive. It is easier to create a 24V output by connecting the two outputs in series. The Dual-800V parallel battery configuration also has some tradeoffs. Advantages It operates with more stability than using 400V period. It is easier to charge, as the parallel combination will see the entire 800V source. In a parallel combination the packs are always at equal voltages. This makes it less complicated to charge. Disadvantages: From a design perspective, the components do need more clearance to the chassis for high voltage safety. A short across the 800V will potentially shut down the entire system. While relatively few vehicles currently utilize a dual 800V battery platform, the redundancy that it offers is important for safety. Without it, the most important car systems are one short away from a catastrophic event. EV power architectures are moving in this direction. Reliability and safety are the biggest reasons for the migration, but newer chargers are compatible with both 400V and 800V, which illustrates further market pull toward 800V. Different factors may preclude choosing one approach over another, but in most cases the Dual-800V battery configuration is preferred for one simple reason. In this system, the power modules make it easy to build in redundancy by using the batteries in parallel. This enables a second power path to the load in the event of a short, protecting the system from total shut down. There are weight and range considerations in addition to the demand on physical space to accommodate two battery packs. While some additional circuitry is required for the battery management system, the safety and reliability benefits outweigh that in the big picture. The many faces of power redundancy—which is best? Implementing redundancy can be done in a number of ways (Figure 3). The load can be shared across two or more DC-DC converters, with the ability of a single converter to take up the entire load should one of the power sources or converters fail. Redundancy can take several forms. Look at the entire power chain from the source to the load and ask; If there would be a failure at this location or portion of the circuitry, What would be impacted? Will the vehicle still drive? What functions will not work? The objective is to be able to continue the driving journey or be able to safely exit the highway off-ramp. Redundancy in a DC-DC converter can take many forms (Figure 3). Some examples are N + 0, N +1, 2N + 1, etc. Each configuration has advantages and disadvantages in terms of size, cost and complexity. A careful study needs to be performed for each vehicle’s architecture. By using a bidirectional DC-DC converter and separating the loads of the vehicle, power can be passed from one zone to the other. Passing the power through a regulator provides a solid source to power the load or even charge a battery. However, today’s current converter technology is not capable of making DCDC converters that are small and light enough to use multiple units in parallel in BEVs. The Vicor BCM® and DCM™ power modules enable easy paralleling. Their Figure 2 — Dual-800V parallel battery configuration. This configuration, allows for lower-current operation and an easier method of implementing an N + 1 redundancy (Source: Vicor) Figure 3 — Several combinations of redundant architectures show power levels and power split in an EV powertrain. The N + 1 has more power capability and therefore can be a larger and more expensive solution. From left to right, the redundancy improves and the power supply more closely matches the load’s requirement, but it also increases component count and system complexity. (Source: Vicor)
12 AUTOMOTIVE POWER www.vicorpower.com Issue 1 2024 Power Electronics Europe www.power-mag.com compact size reduces the overall DC-DC converter footprint and their efficiency and density bolster performance (Figure 4). This augments vehicle range and enables new architectures to enhance safety. High-density power modules unlock creative opportunities and deliver performance and scalability in a way far superior to discrete solutions. Power modules provide up to 3x more power density, enable easy scalability and deliver higher transient speeds that can support down-sizing or removing the 12V/48V auxiliary battery altogether. The BCM (Figure 6) steps down the high-side voltage and multiples the current while providing isolation in a power-dense, highly efficient converter. The BCM is a ratiometric device, where the output is a ratio of the input by a K factor. For example, if the source is 800V in a parallel configuration, the K factor would be 1/16, therefore the low-side voltage is the high-side voltage divided by 16, and the output current is the high-side current multiplied by 16. The Dual-400V series-stacked system uses a similar BCM, however the K factor is 1/8. The DCM3735 regulator takes the voltage from the BCM and provides a tightly regulated output that can charge a capacitor or battery (Figure 5). The combination of BCMs and DCMs enables designers the flexibility to create space and weight efficient, redundant power networks in EVs. Vicor technology can provide 4kw of 800V to 12V power supply in less than 0.9 L. As seen in Figure 4 this system weighs less than 1 kg, and can enable further weight savings by enabling the downsizing of the 12V back-up battery. Consumers want to purchase EVs, but many have reservations. At the top of the list are range and charging convenience. These are not easy problems to solve, but new innovations in power architectures and power density are helping tremendously. Compact power delivery network innovation save weight, which can improve range. Also, the introduction of power modules provides creative latitude and simpler ways to reduce size and weight, which also can deliver more range. The power module is important to solving range, reliability and safety issues. Its scalability and small size adds immense flexibility to designing a power system. Figure 4: This 4kW DC-DC converter uses 2 Vicor BCM6135 and 2 DCM3735 (located on the underside of the board) to convert 800V power to 12V power in a package that weighs 0.08 kg and in a volume of only 0.8575 L. This can be configured into 2 redundant power supplies of 2 kW each, or paralleled with another unit to create a redundant 4 kW power supply. Figure 6 BCM® bus converter. BCMs are high-density, highefficiency, fixed-ratio (nonregulating) isolated DC-DC converter modules. The family extends from 800V or 400V to 48V inputs with various K factors to suit a wide range of applications period. The BCM provides the greatest power density for high-voltage battery conversion to lowvoltage networks. The BCM product family leverages Vicor Sine Amplitude Converter™ technology that results in high-efficiency performance in miniaturized modules. Vicor develops BCMs to match the 400V or 800V battery. Vicor BCMs can be used in arrays to scale to the necessary power requirements. Figure 5: The DCM3735 is a non-isolated, regulated DC-DC converter with an input range of 35-58V. It offers constant current operation for battery charging, comes in a compact package (36.6 x 35.4 x 7.4mm) and can be used in array. When combined with innovative architectures power modules are a catalyst to rapidly advance the long-term adoption of today’s battery electric vehicles. Sources: 1 Kane, Mark (May 10, 2023) “Europe: Plug-In Car Sales Accelerated In March 2023”, INSIDEEVS
www.analog.com POWER SUPPLY DESIGN 13 www.power-mag.com Issue 1 2024 Power Electronics Europe The role of voltage supervisors for system power reliability Voltage supervisors add reliability by monitoring the power supply failures and putting a microcontroller in reset mode to prevent system error and malfunction. By Noel Tenorio, Product Applications Engineer, Analog Devices Power supply imperfections such as noise, voltage glitches, and transients can lead to false and nuisance resets that can affect system behaviour. Voltage supervisors address factors that can trigger false and nuisance resets to improve system performance and reliability. Applications that compute and process data requiring FPGAs, microprocessors, DSPs and microcontrollers depend on safe and reliable operations. These devices tax power supply requirements as they are only allowed to operate at a certain range of power supply tolerance. Voltage supervisors can act immediately to put the system in reset mode when an unexpected failure from the power supply arises, such as under-voltage or over-voltage. Monitoring voltages in power supply rails always comes with some nuisances that can trigger unwanted false reset outputs. These are power supply noises, voltage transients, and glitches that can come from the power supply circuit itself. System glitches Power supplies have inherent imperfections. There are always noise artefacts coupled on the DC that can come from the power supply circuit component itself, noise from other power supplies, and other noise generated from the system. These problems can be worse if the DC power supply is a switch mode power supply (SMPS). SMPS produces switching ripple that is coherently related to the switching frequency. They also produce high frequency switching transients that occur during switching transitions. These transitions are caused by the fast on and off switching of the power MOSFETs. Figure 1 shows an application circuit in which the MAX705 supervisor is used to monitor any failure in the output of the switching regulator, which is the voltage supply of the microcontroller. Aside from the steady-state operation noise artefacts, there are also scenarios in the power supply where voltage transients are more pronounced. During startup, a voltage output over-shoot is usually observed related to the feedback-loop response of the power supply and is followed by voltage ringing for some time until it reaches stability. This ringing can be worse if the feedback loop compensation values are not optimised. Voltage overshoot and under-shoot can also be observed during transient or dynamic loading. In the applications, there are times when the load needs more current to execute complex processes, which leads to a voltage under-shoot. On the other hand, reducing the load instantly or at a fast ramp rate will give a voltage over-shoot. There are also short-duration voltage glitches that can occur to the power supply due to external factors. Figure 2 shows an illustration of the different voltage transients and glitches that can be present on a Figure 1: The MAX705 supervisor is used to monitor a switching regulator output, which is the input voltage supply of a microcontroller. Figure 2: Voltage transients and glitches that can be observed on a supply voltage in different scenarios.
14 POWER SUPPLY DESIGN www.analog.com Issue 1 2024 Power Electronics Europe www.power-mag.com power supply voltage in different scenarios. There are voltage transients that can occur in a system that are not associated with the power supply voltage but rather on a user interface such as a mechanical switch or a conductive card for some applications. Turning a switch on and off produces voltage transients and noise on the input pin, typically a manual reset pin. Power supply noise, voltage transients, and glitches, if excessive, can unintentionally hit the under-voltage or over-voltage threshold of a supervisor and trigger false resets if not accounted for in the design. This can lead to oscillatory behaviour and instability, which is undesirable with regards to system reliability. Noise and transients There are parameters that help mask these transients that are associated with the power supply or monitored voltage. These are the reset timeout period, reset threshold hysteresis, and the reset threshold overdrive versus duration. The transients that are associated with the mechanical contact in the circuit such as a pushbutton switch in the manual reset pin, the manual reset setup period and the debounce time mask the transients. These parameters make the voltage supervisors robust and unaffected by transients and glitches, thus keeping the system from undesirable responses. Reset timeout period (tRP) During startup or when the supply voltage is rising up from an under-voltage event and exceeds the threshold, there is an additional time on the reset signal before it de-asserts, which is called the reset timeout period (tRP). For example, Figure 3 shows that after the monitored voltage, which in this case is the supply voltage labeled as VCC, reaches the threshold from an under-voltage or startup, an added delay is present for an active LOW reset before it de-asserts ‘high’. This additional time gives room for the monitored voltage to stabilise first, masking the over-shoot and ringing before enabling the system or taking it out of reset mode. The reset timeout period suppresses false system resets to prevent oscillation and potential malfunction, thus helping improve the reliability of the system. Threshold hysteresis (VTH+) There are two main benefits of having threshold hysteresis. First, it provides certainty that the monitored voltage has overcome the threshold level with enough margin before de-asserting a reset. Second, it gives room for the power supply to stabilise first before de-asserting a reset. There is a tendency for the reset output to produce multiple transitions when processing signals with superimposed noise, as the power supply bounces and recrosses the threshold region. This is shown in Figure 4. In applications such as industrial environments, noisy signals and voltage fluctuations can occur anytime. Without hysteresis, the reset output will continuously toggle assert and de-assert until the power supply stabilises. It will also put the system into oscillation. Threshold hysteresis cures the oscillation by putting the system hold on reset to prevent the system from unwanted behaviour shown in the blue-shaded area in Figure 4. This helps the supervisor in protecting the system from false resets. Voltage glitches from external factors can occur in any system for either short or long periods. They can also have different magnitudes of voltage dip. Reset threshold overdrive versus transient duration has something to do with the magnitude and duration of the voltage glitch or overdrive. A short-duration glitch with a greater magnitude will not trigger a reset signal to assert, while a less-magnitude overdrive with a longer duration will trigger a reset as shown in Figure 5. Voltage transients in the monitored supply are ignored depending on the duration. Disregarding these transients will protect a system from nuisance resets such as those caused by short-duration glitches. These glitches can falsely trigger system resets, to undesirable behaviour of the system. In the product data sheet, the reset threshold overdrive vs. duration is often illustrated in one of the typical performance characteristics plots such as Figure 3: The reset timeout period (tRP) helps keep the system in reset mode while the supply voltage stabilises. Figure 4: Reset output response without and with threshold hysteresis (reset timeout period not shown to focus on the effect of hysteresis).
www.analog.com POWER SUPPLY DESIGN 15 www.power-mag.com Issue 1 2024 Power Electronics Europe in Figure 6. Any values above the curve will trigger a reset output while values within the curve will be ignored to prevent the system from false resets. Rest and debounce The reset timeout period, threshold overdrive versus duration, and the threshold hysteresis address voltage glitches and transients associated with the monitored voltage, which is usually the power supply of the system microcontroller. For the glitches brought by the mechanical contacts such as switches, the manual reset setup period and the debounce time alleviate the possible effects of the voltage transients and glitches. The manual reset setup period (tMR) is the time required for the manual reset to hold and complete before it triggers a reset output. Some supervisors are made to have a long manual reset setup period to add protection to the system. These are common on consumer products on which the button needs to be held for several seconds to reset the system. This method avoids accidental and unintended reset, thus adding protection and reliability. With the manual reset setup period, all the short-duration transients and glitches when pushing on the switch are ignored, as shown in Figure 7a, thus helping the system to be glitch immune. The same concept applies to the debounce time. Like the setup period, debounce time (tDB) ignores the high frequency periodic voltage transients when pushing on or off a switch. These high frequency transients are considered invalid and do not trigger a reset as shown in Figure 7b. When the signal exceeds the debounce time, that is the time it will be considered a valid input signal from a switch or a push button. Conclusion Without voltage supervisors, systems are at risk of brownout conditions and malfunction during voltage transients and glitches. Voltage supervisors solve this by putting processors into reset mode during such scenarios, All the parameters discussed here, including reset timeout period, threshold hysteresis, threshold overdrive, manual reset setup period and debounce time, improve the reliability of voltage supervisors in monitoring power supply voltages by making them immune to glitches and transients. This gives stability and reliability to overall system performance. Figure 7: The manual reset setup period and debounce time diagram of a supervisor with a long manual reset setup period (MAX6444). The manual reset setup period (tMR) needs to be completed first before a reset signal asserts (a) and debounce time (tDB) is required (b) to be considered as a valid input signal. Figure 6: Asserting of the reset signal will depend on the magnitude of the overdrive and its duration. Figure 5: A glitch with a less magnitude but occurs in a longer duration will trigger a reset signal as opposed to a short-duration glitch with greater magnitude.
16 TELECOMMS POWER https://www.advancedenergy.com Issue 1 2024 Power Electronics Europe www.power-mag.com Power choices to minimise maintenance The choice of power source can reduce telecomms maintenance cost. By Andy Brown, Director, Technical Marketing DC/DC, Advanced Energy Industries The telecomms RAN (radio access network) is essential to almost every aspect of our daily lives and operators are being challenged to deliver ever greater capacities and coverage with high uptime and low costs. Unsurprisingly, energy is one of the largest operating costs for cells and towers that support the RAN infrastructure. Meanwhile, the power consumption of macro cell radios has increased steadily as access technologies have evolved. Typical power consumption for radio units was in the range of 100 to 300W in 2001 and is estimated to reach up to 1,800W by 20301. As a result, careful selection of the power supply, converter and power management technologies is a fundamental aspect to enabling modern RAN design. However, there is another significant cost associated with running a RAN that can also be impacted by the choice of power technologies, namely maintenance. Unplanned downtime and maintenance costs can mount very quickly, reaching many hundreds if not thousands of times the cost of any specific part or system that has failed. The cost of failure Consider a large network such that has 100,000 cell sites in a network. Each will have a variety of power supplies and modules, including AC/DC and DC/DC converters (Figure 1). There are two key areas for power supply technologies in a RAN infrastructure. One is the DC/DC converters that support the power amplifiers in the integrated radio antennas and the second are the high-power systems deployed in base station controllers. In terms of a DC/DC converter in a remote radio head (RRH), even the highest quality, well-engineered module may have a failure rate of about 10ppm (parts per million), so it would be expected to exhibit failure at some point. Once time is factored in to diagnose the fault, and an engineer is dispatched to ascend the antenna and fix the problem, costs can run to many thousands of dollars. Actual costs will vary depending on the individual scenario. However, an approximate cost of $20,000 to $30,000 to repair a fault of a failed DC/DC converter located in the RRH equipment is many times the value of the DC/DC converter itself. Figure 2 shows the key factors contributing to such a cost might break down. As the cost of the converter is likely to be in the range of $50, the cost of repair makes the cost of the original part negligible in comparison. If a batch of DC/DC converters has a latent fault, the ppm failure rate could be higher. Furthermore, if this were to reach 500ppm, then the same network could experience 50 failures at a significant cost. While clearly these figures are just for illustration purposes and could be debated, it is clear that component / module fallibility has the potential to drive Figure 1: Power modules for RAN applications.
https://www.advancedenergy.com TELECOMMS POWER 17 www.power-mag.com Issue 1 2024 Power Electronics Europe product suitable for supplying power to a power amplifier in telecomms and datacomms applications. It operates at 95% efficiency with demonstrated long term field failure rates under 15ppm. The Artesyn ADH700 700W half brick converter also operates at efficiencies at or above 95% and its thermal management allows it to operate at full power in enclosed spaces with a baseplate temperature up to 100ºC. Designers that understand how a design can impact maintenance costs take a more conservative approach to tolerances and design margins – especially in terms of thermal and electrical stress. This ensures components operate at levels that reduce the likelihood of failure. Focusing the component selection process on reliability, rather than cost, can lead to a dramatic reduction in field failures. While calculated MTTF (mean time to failure) data is a good first step, choosing power products that have been tested to an IPC9592based qualification process often has more relevance and benefit. Working with an experienced telecomms supplier brings greater likelihood of design success as there is a pathway to leverage the many years of experience designing power modules for Tier 1 OEMs that operate in the telecomms space. As well as direct cost savings that can be attributed to maintaining and repairing the infrastructure there are also several indirect cost benefits that result from a more robust approach to designing in reliability from the start. Engineers, for example, can spend less time on failure analysis and field repairs and more time developing those products and systems that will generate future revenues. Even more intangible, but still important, is the fact that minimising callouts at unsociable hours reduces the impact on the morale of employees, improving the quality of their work and minimising possible retention, hiring and training costs. TCO is key The true impact of reliability in a telecomms network cannot be underestimated, whether in terms of direct and indirect maintenance costs, lost revenue through downtime or more intangible factors including customer loyalty and a de-motivated workforce. Power amplifiers and the circuits that support them represent critical elements of a RAN infrastructure, and ensuring reliable, long term operation in harsh environments is fundamental to successful implementation. Taking a total cost of ownership (TCO) approach that goes beyond just the pieceprice and operational expense related to conversion efficiency is key to success when choosing and designing products - including the power conversion technologies at the heart of the RAN hardware. Market innovators must widen the definition of TCO to include the very real and considerable costs associated with any potential field failures or compromised network performance. This thinking leads to an emphasis on product reliability beyond just using the usual calculated mean time between failures (MTBF) figure as a benchmark data point between supplier solutions. As a result, wireless access system designers are now focusing their efforts to reduce the overall cost of ownership by designing systems in a way that significantly reduces the number of unscheduled maintenance incidents and the consequences caused by product failures. very significant costs for a network operator. The piece-part cost of a DC/DC module becomes almost irrelevant once the true cost of long-term unplanned maintenance is understood. Therefore, engineers need to design power architectures that meet performance requirements as well as the current, voltage and power specifications of an individual design and create them with optimum reliability in mind. As a failure in the field can cost hundreds, or even thousands, of dollars, the cost of the individual component is very sobering and precludes any cutting of corners in the design and qualification process. Component selection Operating efficiency is a critically important factor when selecting a power component. Efficiency has become more important in product design. This is driven by commercial demands i.e., more efficient components reduce the total cost of ownership by driving down energy costs and also legislative pressures relating to sustainability. Efficiency plays a fundamental role in reliability because of the consequent excess heat in causing component failures. The rule of thumb is that every 10°C increase in temperature reduces the life of electronics by 50% although this is a broad approximation. It is clear that elevated temperatures reduce the operating life of both the power components themselves and other components around them. For this reason, power supply manufacturers are developing high performance power products that deliver percentage levels of efficiency well into the high nineties. Advanced Energy’s AVE450B 450W single output, half brick DC/DC converter, for example, is a Figure 2: Example breakdown of costs to rectify a DC/DC converter failure in a RRH
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