https://toshiba.semicon-storage.com/ HEAT PUMPS 21 www.power-mag.com Issue 1 2025 Power Electronics Europe Heat pumps call for optimised solutions Frank Malik, Radoslav Valchev, Toshiba Electronics Europe GmbH The heat pump has become the leading choice for low-carbon heating and airconditioning. Thanks to its high coefficient of performance (COP), it can deliver far more efficient temperature control to the home and office than conventional systems, such as gas boilers. To ensure the technology is used as widely as possible in the drive to netzero, manufacturers will need to look carefully at the bill of materials and system cost. Reference designs provide valuable guidance to them as they illustrate how a variety of components can deliver more than the sum of their parts by taking into account how different technologies can support each other. The result is a design that both minimises the cost of the subsystem and reduces development time. The concept behind the heat pump is powerful but simple, using an exchange of heat with the building surroundings by selectively compressing and expanding a refrigerant gas. Using this process, the heat pump achieves optimal energy utilisation, delivering more than 7kW of heat using just 1kW of electrical power under optimum conditions. Practical considerations and temperature variations over the year reduce the calculated efficiency. Even so, it is common to achieve figures ranging from 2.5 to 5. That compares well to a conventional water boiler. This will deliver only about 90% of the delivered power into useful heat, resulting in a COP of less than 1. Motor control is key to effective thermal exchange, lowering losses and optimal use of energy. There are several important locations for motor controllers inside heat pumps, which are normally divided into two modules. One of these modules normally sits outdoors. This unit contains a tank that provides the refrigerant used throughout the heating and cooling system alongside a compressor, fan, and an evaporator/condenser unit. In most cases, a smaller indoor unit contains motors that direct the flow of fluid through the heating system. It also contains a second evaporator/condenser unit and the user interface panel. The two units exchange heat between the indoor and outdoor environment using a refrigeration-type process that uses paired compression-condensation or expansion-evaporation cycles, depending on whether the indoor environment needs heating or cooling. Toshiba developed the RD219 reference design to help support engineers deliver an efficient heat pump system. At its core is a single MCU combined with low-loss power components in an architecture that optimises the bill of materials. Focus on power conversion Power-conversion technology plays a vital role throughout the design. The compressor and fluid and air pumps represent key locations for motor controllers. Circulating pumps and valves, based on either motors or solenoids, help control the flow of refrigerant gas or liquid through the indoor heating system. Low-power permanent-magnet
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