Power electronics unit for heat pumps

Abstract

The invention relates to a power electronics unit for heat pumps, comprising − power electronics (5) configured for the open-loop / closed-loop control and operation of a compressor of a heat pump and having a circuit board (16), and − at least one control unit (6, 8) integrated in the power electronics unit (1), wherein all the elements of the power electronics (5) are arranged on the circuit board (16), the control unit (8) is connected to at least one sensor and at least one expansion valve of the heat pump, and the control unit (8) is configured to acquire sensor data and to adjust the position or opening width of the expansion valves.

Description

[0001] ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0002] Power electronics unit for heat pumps

[0003] Description

[0004] Technical field

[0005] The present invention relates to a power electronics unit for heat pumps.

[0006] Furthermore, the invention relates to a heat pump for a motor vehicle with a power electronics unit for heat pumps. The heat pump is characterized in that the power electronics unit for heat pumps is designed as described.

[0007] Furthermore, the invention relates to a thermal management system for a motor vehicle comprising a heat pump, a distribution unit, and a compressor. The thermal management system is characterized by the fact that the heat pump is designed as described.

[0008] background

[0009] In state-of-the-art technology, the power electronics of a heat pump comprise several key components that primarily regulate the operation of the compressor. The compressor, as the central element of the heat pump, is controlled by a frequency converter, which adjusts the motor speed and thus enables precise regulation of the compressor output. A soft starter additionally ensures a smooth start-up of the compressor to minimize current spikes and mechanical stress.

[0010] An electronic expansion valve regulates the refrigerant flow through the system by adjusting its opening width according to sensor data such as pressure and temperature measurements. These valves are supplied by a separate ZF Friedrichshafen AG file 305507 Friedrichshafen 2024-09-26

[0011] A control unit, using microcontrollers or programmable logic controllers (PLCs), ensures optimized heat transfer and efficient operation. Sensors, such as temperature, pressure, and flow sensors, continuously transmit readings to the central control unit, which then makes the necessary adjustments to the various system components. Communication interfaces like Modbus or CAN bus enable connection to external control systems and remote monitoring, while integrated safety features such as overcurrent protection, overtemperature protection, and fault detection ensure reliable and safe operation.

[0012] The problem is that conventional heat pump power electronics are primarily designed for controlling and regulating the compressor, as it is the central element for the system's operation and has the highest energy consumption. Controlling the compressor with frequency converters and soft starters allows for precise adjustment of the power output to the specific operating conditions, maximizing efficiency and reducing energy consumption.

[0013] This focus on the compressor means that the power electronics do not include specific controllers / control units for additional components such as sensors or expansion valves. Sensors and expansion valves are often considered "secondary" elements, and their control is therefore usually handled by separate control units or via a central building management system that is not directly integrated into the power electronics.

[0014] Controlling these components requires continuous acquisition and processing of variable data, as well as the ability to react quickly to different operating conditions—requirements often not provided for in current power electronics architecture. Therefore, specific control units for sensors and expansion valves are lacking in conventional power electronics. ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0015] Furthermore, the current state of the art dictates that each component of a heat pump requires its own circuit board with individual controls. This leads to increased cabling and installation costs for several reasons:

[0016] Firstly, each circuit board requires separate development, manufacturing, and installation, increasing both effort and costs. Furthermore, the large number of circuit boards necessitates extensive wiring to ensure communication and power supply between the components. Finally, the installation and connection of the numerous circuit boards and cables increases assembly effort and thus assembly costs. Since the circuit boards and cables require additional space, integration into the overall heat pump system becomes difficult or even impossible, preventing the circuit board components from being placed where the hardware components are located. This hinders the implementation of an optimized and cost-effective assembly and interconnection technology (AIT).

[0017] Summary description of the invention

[0018] Therefore, one of the problems underlying the present invention is to overcome the disadvantages of a power electronics unit for heat pumps in the prior art.

[0019] In particular, one of the problems underlying the present invention is to provide a power electronics unit for heat pumps that features improved assembly and interconnection technology (AIT), allowing the circuit board components to be placed where the hardware components are located, thus enabling optimized and cost-effective AIT. This and other problems are solved by the subject matter of the appended independent claims.

[0020] Preferred embodiments can be found in the dependent claims and furthermore in the following description, in particular taking into account various embodiments as discussed and described in the attached claims.

[0021] The embodiments, features and combinations of features as described herein in connection with the invention, as well as the combination of ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0022] Features as specified in the appended claims, as well as any combination of features as mentioned and described in connection with the embodiments, are deemed disclosed herein, or at least derivable by a person skilled in the art. In particular, each feature and each combination of features in the embodiments described herein may, for example, be claimed in a different combination, especially in a different claim category, at least because the person skilled in the art will recognize that each individual combination of the features mentioned herein is suitable for contributing to the solution of the underlying problem.

[0023] Furthermore, each feature and each combination of features in the claims and in the description below can be used and claimed separately, independently of the subject matter claimed, independent of claim dependencies and cross-references, and independent of the claim category in which the feature is claimed. For example, in an arbitrary combination selected from one or more claims, one or more embodiments according to the description below and / or the accompanying figures may be provided.

[0024] The problems described above are solved according to the invention by a power electronics unit for heat pumps, comprising:

[0025] - a power electronics unit designed for the control / regulation and operation of a compressor of a heat pump, comprising a circuit board, and

[0026] - at least one control unit integrated in the power electronics unit, wherein all elements of the power electronics are arranged on a circuit board, wherein the control unit is connected to at least one sensor and at least one expansion valve of the heat pump, and wherein the control unit is designed to acquire sensor data and to adjust the position or opening width of the expansion valves.

[0027] Integrating the control unit into the power electronics unit significantly simplifies the system design and reduces the footprint, resulting in a more compact and cost-effective solution. This integration minimizes the number of components required, reducing material costs and simplifying wiring and assembly. The result is a more robust and reliable solution that is less prone to failure.

[0028] Continuous monitoring by the sensors enables a fast and precise response to changes in operating conditions. This is particularly important for maximizing the efficiency and performance of the heat pump. Real-time monitoring allows potential problems to be detected and resolved early, before they lead to major malfunctions. This significantly contributes to increasing the reliability and lifespan of the heat pump, as the components are subjected to less stress and therefore last longer.

[0029] Furthermore, the optimized control and regulation contribute to a significant reduction in energy consumption. By precisely adjusting the operating parameters to the current requirements, the heat pump can operate more efficiently and consume less energy. This is not only environmentally friendly, as CO2 emissions are reduced, but also saves the end user money by lowering operating costs.

[0030] The unit is also more compact and highly integrated, with fewer interfaces. Externally, only the communication and power supply interfaces are present, connected via two plugs. This significantly simplifies installation and maintenance, as fewer connections need to be made and checked. This reduces the likelihood of installation errors and resulting malfunctions. Furthermore, maintenance is simplified because fewer components need to be inspected and serviced, further reducing operating costs.

[0031] This also provides improved assembly and interconnection technology (AVT), allowing the circuit board components to be placed where the hardware components are used, thus enabling optimized and cost-effective AVT.

[0032] In this context, a control unit is an electronic component or chip responsible for controlling and regulating functions within an electronic device. A control unit can perform tasks such as processing signals, controlling processes, communicating with other components, and executing commands. Examples of control units on a circuit board include controllers or microcontrollers, which are frequently used in embedded systems to manage specific tasks such as sensor control, motor control, or interface communication.

[0033] In the present description and the accompanying claims, unless the context otherwise requires, the word “comprise” and variations such as “includes” and “comprehensive” are understood to imply the inclusion of a specified element, integer, or step, or group of elements, integers, or steps, but not the exclusion of any other element, integer, or step, or group of elements, integers, or steps, although in some embodiments such other elements, integers, or steps, or groups of elements, integers, or steps may be excluded; i.e., the subject matter consists of the inclusion of a specified element, integer, or step, or group of elements, integers, or steps.

[0034] The terms “a”, “an”, and “that”, and similar references used in the context of the description of the invention (particularly in the context of the claims) are to be interpreted as covering both the singular and the plural, unless otherwise specified herein or clearly contradicted by the context. The indication of value ranges serves only as a shorthand way to refer individually to each value within the range. Unless otherwise specified herein, each individual value is included in the specification as if it were listed individually herein.

[0035] Within the present application, terms such as “side” or “lateral”, “rear”, “front”, “top”, “bottom”, “ground”, “opposite”, “inside”, “outside” or the like, which describe the position of a first object relative to another object, preferably refer to the relative position of a respective part or ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0036] object in relation to its position when it is fully assembled for its intended use.

[0037] In a preferred embodiment of the power electronics unit for heat pumps according to the invention, this unit can include a further control unit.

[0038] If the power electronics unit for heat pumps according to the invention includes an additional control unit, the system is more flexible and adaptable. The additional control unit allows specific tasks or functions to be controlled and optimized separately, resulting in improved overall performance and efficiency.

[0039] Furthermore, the second control unit enables redundancy, which increases the reliability and fault tolerance of the system, since in the event of a control unit failure, the other control unit can take over the control.

[0040] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, a low-voltage area and a high-voltage area can be physically separated from each other.

[0041] Physical separation means that there is no direct electrical connection between different parts of the system, thus preventing electrical disturbances or faults from being transmitted from one part of the system to another. This can be achieved, in particular, through galvanic isolation.

[0042] Despite this physical separation, the components of the power electronics unit must continue to function as a single unit. The components are located on a common circuit board, which facilitates a compact design and easy integration. The circuit board serves as a carrier for the various components and ensures that they are mechanically stable and electrically connected, even with galvanic isolation. ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0043] This offers increased safety and reliability of the system. The physical separation of the two voltage ranges significantly reduces the risk of short circuits and other electrical disturbances.

[0044] This not only contributes to the safety of users, but also protects sensitive electronic components from damage caused by overvoltages or electrical interference.

[0045] Furthermore, the separation facilitates the maintenance and repair of the unit, as technicians can work specifically in one voltage range without affecting the other.

[0046] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, a flyback converter can be arranged for voltage conversion between the high-voltage range and the low-voltage range.

[0047] A flyback converter offers several advantages when used to convert voltage between a high-voltage and a low-voltage range. One of the main advantages of a flyback converter is its ability to provide galvanic isolation between the input and output. This isolation is particularly important in applications where safe isolation between the different voltage levels is required to protect users and equipment.

[0048] Another advantage of the flyback converter lies in its versatility and efficiency. It can operate as both a boost and a buck converter, meaning it can transform a high input voltage to a low output voltage (or vice versa), depending on the requirements of the specific application.

[0049] Furthermore, the flyback converter is cost-effective due to its simple construction and can be easily implemented in various circuit designs. It requires only a few components such as a transformer, a switching device (e.g., a transistor), and some passive components, which reduces its cost. (ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26)

[0050] Complexity reduced. The simple circuit configuration allows it to operate in a wide voltage range, making it ideal for voltage conversion between high and low voltage ranges.

[0051] Additionally, the voltage converter used can also be a flyback converter, which is known for its high efficiency and flexibility in voltage conversion. These characteristics make it particularly suitable for converting voltages in systems that encompass both high-voltage and low-voltage ranges.

[0052] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, one control unit can be arranged in the low-voltage range and the other in the high-voltage range.

[0053] By separating the voltage ranges, the power electronics unit can operate more efficiently, as each control unit is optimally matched to its specific voltage range.

[0054] Furthermore, separating the voltage ranges increases safety, as the high-voltage components can be isolated and operated separately from the low-voltage components. This arrangement also allows for greater flexibility in the design and adaptation of the power electronics unit, since the control units can operate independently of each other.

[0055] Another advantage is the reduction of electromagnetic interference due to the spatial separation of the control units, resulting in more stable and reliable performance. Finally, separating the voltage ranges facilitates maintenance and repair of the power electronics unit, as the individual components are more easily accessible and replaceable.

[0056] In a further preferred embodiment of the power electronics unit according to the invention for heat pumps, the components arranged in the high-voltage area can comprise a voltage range of 400 V to 1000 V, ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26, preferably 400 V to 850 V, more preferably 400 V to 800 V, and / or the components arranged in the low-voltage area can comprise a voltage range of 48 V or less.

[0057] The voltage can be flexibly adjusted. The ability to use high-voltage components with a voltage range of 400 V to 1000 V, preferably 400 V to 850 V, and more preferably 400 V to 800 V, and low-voltage components with a voltage range of 48 V or less, allows the unit to be used more efficiently and in a more versatile manner. This enables better adaptation to different operating conditions.

[0058] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, the circuit board can include an EMC filter, preferably a single EMC filter.

[0059] An EMC filter (electromagnetic compatibility filter) is a component designed to reduce or eliminate electromagnetic interference that could impair the function of electronic devices. It typically consists of inductors and capacitors that block high-frequency interference while allowing desired signals to pass through.

[0060] This reduces the complexity of the design, as only one filter needs to be integrated. This simplifies manufacturing and can lower production costs.

[0061] Furthermore, a single EMC filter can improve the electromagnetic compatibility (EMC) of the entire unit by filtering interference more efficiently, thus increasing the reliability and performance of the heat pump.

[0062] Furthermore, maintenance and filter replacement can be simpler and more cost-effective, as only one filter needs to be monitored and replaced if necessary. ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0063] Finally, integrating a single EMC filter can save space on the circuit board, leading to more compact and efficient designs.

[0064] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, the EMC filter can include a common-mode choke and / or can include at least one X- and Y-class capacitor.

[0065] These components help minimize electromagnetic interference, which increases the reliability and stability of the system. Furthermore, reducing interference and optimizing the power supply can improve the energy efficiency of the heat pump.

[0066] Furthermore, fewer disturbances and a more stable power supply contribute to extending the lifespan of the electronic components.

[0067] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, a plurality of the components of the power electronics unit can be arranged such that the connections to the respective hardware components have the shortest possible distance.

[0068] By arranging the components along the shortest possible path to their respective hardware components, the efficiency of energy transfer is maximized, resulting in improved overall performance of the heat pump. Furthermore, the shorter connections minimize potential energy losses.

[0069] Furthermore, the compact arrangement of the components reduces the space required and facilitates the integration of the unit into various systems. Another advantage is the reduction of wiring on the circuit board, which not only reduces material costs but also increases the reliability and ease of maintenance of the unit.

[0070] In a further preferred embodiment of the power electronics unit according to the invention for heat pumps, one or two valve controllers (ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26) can further comprise one or two valve controllers designed to control / regulate the flow of liquids or gases in a heat pump system, and can comprise two or three controllers for temperature sensors, wherein at least two of the controllers for temperature sensors can be controllers for PT sensors.

[0071] The ability to integrate one or two valve controls allows the system to respond flexibly to varying requirements. Controls for the temperature sensors, particularly the PT sensors, enable precise temperature adjustment and monitoring. This results in variable and adaptable performance of the heat pump system.

[0072] PT sensors (platinum temperature sensors) are resistance temperature sensors made of platinum and used to measure temperature. They operate on the principle that the electrical resistance of platinum changes with temperature.

[0073] In a further preferred embodiment of the power electronics unit according to the invention for heat pumps, the power electronics unit can be arranged to be attached to the bottom or top surface or to one of the longitudinal side surfaces of the outer skin of a heat pump.

[0074] This allows for easy installation and integration into existing systems and can improve the efficiency and performance of the heat pump, as the electronic unit can be optimally positioned.

[0075] Furthermore, this arrangement can minimize space requirements and facilitate maintenance, as the electronics unit is easily accessible.

[0076] Finally, the design according to the invention contributes to the longevity and reliability of the heat pump by providing a robust and well-protected electronic unit that withstands external conditions. ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0077] In this context, it should be noted that the terms "bottom", "top" and "longitudinal side surface" preferably refer to the relative position of a heat pump in relation to the position when it is fully installed for its intended use.

[0078] In a further preferred embodiment of the power electronics unit for heat pumps according to the invention, an energy storage component may also be included.

[0079] By integrating an energy storage system, the heat pump can store excess energy and retrieve it as needed, resulting in better energy efficiency and lower operating costs. Furthermore, the energy storage component enables a continuous and stable heat supply, even with fluctuating energy sources. This makes the system not only more environmentally friendly but also more economical.

[0080] Furthermore, the invention relates to a heat pump with a power electronics unit for heat pumps. The heat pump is characterized in that the power electronics unit for heat pumps is designed as described.

[0081] Furthermore, the invention relates to a thermal management system for a motor vehicle comprising a heat pump, a distribution unit, and a compressor. The thermal management system is characterized by the fact that the heat pump is designed as described.

[0082] In addition, the invention relates to a motor vehicle comprising a thermal management system and / or a heat pump / distribution unit / compressor and / or a power electronics unit for heat pumps according to the invention.

[0083] A thermal management system is a system that regulates the temperature of at least two consumers. A consumer is therefore a device that needs to be cooled or heated. One consumer can be cooled and the other heated. ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0084] Furthermore, the invention relates to a building with a thermal management system and / or a heat pump / distribution unit / compressor and / or a power electronics unit for heat pumps. The building is characterized in that the thermal management system and / or the heat pump / distribution unit / compressor and / or the power electronics unit for heat pumps is designed as described.

[0085] Brief description of the characters

[0086] The present invention is explained in more detail below with reference to the drawings, from which further features, embodiments, and advantages can be derived. In the embodiments shown in the figures, elements that have similar or identical functions are designated with the same reference numerals. It should be noted that the figures may not be to scale.

[0087] This shows:

[0088] FIG 1 shows a schematic representation of a power electronics unit for heat pumps.

[0089] Detailed description

[0090] FIG. 1 shows a schematic representation of a power electronics unit for heat pumps. This comprises a power electronics unit 5, designed for the control / regulation and operation of a compressor of the heat pump, comprising a circuit board 16, and a control unit 6 and 8 integrated into the power electronics unit.

[0091] All power electronics elements 5 are arranged on circuit board 16, resulting in a compact design, fewer interfaces, and improved efficiency. This also allows for improved assembly and interconnection technology (AIT), enabling the circuit board components to be placed where ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0092] Hardware components are used, enabling optimized and cost-effective AVT.

[0093] The power electronics unit 1 is designed to include both a low-voltage section 4 and a high-voltage section 2, which are physically separated from each other by, for example, galvanic isolation 12. A flyback converter 10 is arranged for voltage conversion between these two sections 2 and 4.

[0094] The control units 6 and 8 are arranged accordingly in the low-voltage 4 and high-voltage 2 areas, with one control unit 6 located in a low-voltage area 6 and the other control unit 8 located in a high-voltage area 8. However, it is also possible for the power electronics unit to comprise only one control unit or a plurality (more than two) of control units.

[0095] The components in the high-voltage range 2 cover voltages from 400 V to 1000 V, preferably 400 V to 850 V, and more preferably 400 V to 800 V, while the components in the low-voltage range 4 cover voltages of 48 V or less. The circuit board 16 contains a single EMC filter 14, which includes a common-mode choke and / or X- and Y-class capacitors.

[0096] Control units 6 and 8 are connected to at least one sensor and one expansion valve of the heat pump. They are designed to acquire sensor data and, based on this data, adjust the position or opening width of the expansion valves. This enables precise control and optimization of the heat pump's performance.

[0097] The components of the power electronics unit 1 are arranged in such a way that the connections to the respective hardware components have the shortest possible distance.

[0098] The unit further comprises one or two valve controllers for regulating the flow of liquids or gases, and two or three controllers for temperature sensors, at least two of which are designed for PT sensors. ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0099] The power electronics unit 1 is designed to be mounted on the outer casing of a heat pump, either on the top or bottom surface, or on one of the longitudinal side surfaces. These specifications refer to the installed state of the heat pump.

[0100] Additionally, the unit may include an energy storage component.

[0101] This power electronics unit 1 can be integrated into a heat pump that is part of a thermal management system for motor vehicles. The thermal management system includes a heat pump, a distribution unit, and a compressor.

[0102] ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26

[0103] Reference mark

[0104] 1 power electronics unit for heat pumps

[0105] 2 High-voltage area

[0106] 4 Low voltage range

[0107] 5 Power Electronics

[0108] 6 Control unit in the low-voltage range

[0109] 8 Control unit in the high-voltage area

[0110] 10 flyback converters

[0111] 12 galvanic isolation

[0112] 14 EMC filters

[0113] 16 circuit boards

Claims

ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26 Patent claims 1. Power electronics unit for heat pumps, comprising: - a power electronics (5) designed for the control / regulation and operation of a compressor of a heat pump, comprising a circuit board (16), and - at least one control unit (6, 8) integrated in the power electronics unit (1), wherein all elements of the power electronics (5) are arranged on the circuit board (16), wherein the control unit (8) is connected to at least one sensor and at least one expansion valve of the heat pump, and wherein the control unit (8) is designed to acquire sensor data and to adjust the position or opening width of the expansion valves.

2. Power electronics unit (1 ) for heat pumps according to claim 1 further comprising a further control unit (6, 8).

3. Power electronics unit (1 ) for heat pumps according to claim 1 or 2, wherein a low voltage area (4) and a high voltage area (2) are physically separated from each other.

4. Power electronics unit (1 ) for heat pumps according to claim 3, wherein a flyback converter (10) is arranged for voltage conversion between the high voltage range (2) and the low voltage range (4).

5. Power electronics unit (1 ) for heat pumps according to claim 2 and claim 3 or 4, wherein one control unit (6) is arranged in the low voltage area (4) and the other (8) is arranged in the high voltage area (2). ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26 6. Power electronics unit (1) for heat pumps according to one of claims 3, 4 or 5, wherein the components arranged in the high voltage area (2) comprise a voltage range of 400 V to 1000 V, preferably 400 V to 850 V, more preferably 400 V to 800 V, and / or the components arranged in the low voltage area (4) comprise a voltage range of 48 V or less.

7. Power electronics unit (1 ) for heat pumps according to one of the preceding claims, wherein the circuit board (16) comprises an, preferably a single, EMC filter (16).

8. Power electronics unit (1 ) for heat pumps according to claim 7, wherein the EMC filter (16) comprises a common-mode choke and / or at least one X and Y class capacitor.

9. Power electronics unit (1 ) for heat pumps according to one of the preceding claims, wherein a plurality of the components of the power electronics unit (1 ) are arranged such that the connections to the respective hardware components have the shortest possible distance.

10. Power electronics unit (1) for heat pumps according to one of the preceding claims, further comprising one or two valve controls designed to control / regulate the flow of liquids or gases in a system of a heat pump, and two or three temperature sensor controls, wherein at least two of the temperature sensor controls are PT sensor controls.

11. Power electronics unit (1) for heat pumps according to one of the preceding claims, ZF Friedrichshafen AG File 305507 Friedrichshafen 2024-09-26 wherein the power electronics unit (1) is designed to be attached to the bottom or top surface or to one of the longitudinal side surfaces of the outer skin of a heat pump.

12. Power electronics unit (1 ) for heat pumps according to one of the preceding claims, further comprising an energy storage component.

13. Heat pump with a power electronics unit (1 ) for heat pumps, characterized in that the power electronics unit (1 ) for heat pumps is designed according to one of the preceding claims.

14. Thermal management system, in particular for a motor vehicle, comprising a heat pump, a distribution unit and a compressor, characterized in that the heat pump is designed according to claim 13.

15. Motor vehicle comprising a thermal management system according to claim 14 and / or a heat pump according to claim 13 and / or a power electronics unit (1 ) for heat pumps according to any one of claims 1 to 12.

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