Drives & Controls October 2022

n TECHNOLOGY October 2022 www.drivesncontrols.com 16 AUSTRALIANRESEARCHERS have built a high-speed electric motor that, they claim, is much more robust than other IPMSMs (interior permanent magnet synchronous motors), while using far fewer rare-earth materials and being cheaper. The prototype motor has achieved speeds of 100,000 rpm, more than doubling the previous speed record for laminated IPMSMs, according to the developers. IPMSMmotors have magnets embedded in their rotors to create powerful torque for extended speed ranges. However, most existing IPMSMs suffer from lowmechanical strength because of thin iron bridges in their rotors that limit their top speeds. The researchers from the University of New SouthWales School of Electrical Engineering and Telecommunications have patented a new rotor topology which improves robustness“significantly”, while also cutting the amount of rare-earth materials needed. The design was inspired by the two-arch design of a South Korea’n rail bridge. The team, headed by associate professor Rukmi Dutta and Dr Guoyu Chu, developed the motor using their own AI-assisted optimisation programwhich evaluated a series of designs for different physical aspects – electrical, magnetic, mechanical and thermal. It assessed 90 potential designs, then selected the best options to generate a new range of designs, until the optimum design was achieved. The final motor was the 120th generation analysed by the program. “We can input the requirements of speed, or power density and run the system for a couple of weeks and it gives us the optimum design that satisfies those needs,”explains Dr Chu. “Most high-speed motors use a sleeve to strengthen the rotors and that sleeve is usually made of high-cost material such as titanium or carbon fibre,”he adds.“The sleeve itself is very expensive and also needs to be precisely fitted and that increases the manufacturing cost of the motor. “Our rotors have very good mechanical robustness, so we don’t need that sleeve, which reduces the manufacturing cost. And we only use around 30% of the rare-earth materials of other motors, resulting in a big reduction in material costs – making our motors more environmentally friendly and affordable.” The researchers believe that their motor has many potential applications, including in large HVAC systems that need high- speed compressors for use with new refrigerants with reduced global warming effects. The high-speed motors could also be used to allow precision CNC machines to mill or drill with small diameters. Another potential application is providing electrical power on aircraft. Perhaps the most promising use for the motors is in electric vehicles, where they could save weight and extend ranges.“One of the trends for EVs is for them to have motors which rotate at higher speeds,”says Dr Chu.“Every EV manufacturer is trying to develop high-speed motors and the reason is that the laws of physics then allow you to shrink the size of that machine. And with a smaller machine, it weighs less and consumes less energy and gives the vehicle a longer range. “With this research project we have tried to achieve the absolute maximum speed, and we have recorded over 100,000 rpm and the peak power density is around 7kW per kilogram. “For an EV motor we would actually reduce the speed somewhat, but that also increases its power,”he continues.“We can scale and optimise to provide power and speed in a given range – for example, a 200kWmotor with a top speed of around 18,000 rpm that perfectly suits EV applications. “We only use around 30% of the rare-earth materials of other motors, resulting in a big reduction in material costs” LEUZE HAS ANNOUNCED a safety positioning system for applications such as stacker cranes that uses a single sensor to detect positions instead of the two needed previously. Until now, two sensors using different technologies have had to be used in a redundant configuration to monitor the speed and position of equipment such as stacker cranes to ensure that they pose no danger to personnel during maintenance or when operating with a manned cab. This set-up has been needed to meet PL d. Leuze claims that its new FBPS 600i single-sensor barcode positioning system meets PL e using a single sensor. This makes it easier to implement safety functions as well as saving space, and simplifying installation. The sensor detects a tough, UV-resistant barcode tape fixed to the opposite rack. With every scanning pass, it reads multiple codes, from which software determines precise positions. The sensor scans the code at various locations to avoid errors caused by dirt or damage to the tape. The sensor has an error reaction time of 10ms, making it suitable for detecting positions involving rapid movements. Parameters such as speed curves and throughput can be optimised. The sensor’s working range of 50–170mm allows flexible integration in different applications. The sensor is connected to a safety evaluation system, such as a drive, via two SSI interfaces. n Single-sensor positioning system for safety apps is ‘world’s first’ Aussie motor ‘doubles speed record’ and cuts rare-earth use A prototype of the new Australian motor on a test bench