TEMPERATURE ESTIMATION FOR POWER ELECTRONICS

Abstract

Temperature monitoring systems and processes in power electronics determine at least one temperature based on the operating characteristics of the power electronics system. The operating characteristics are used to determine a power loss using a model of the power electronics system. The power loss is then used to determine the temperature using a thermal model of the power electronics system. The temperature can be used to control the power electronics system, for example, by enabling cooling control such as fan speed control, compensating for temperature effects on the power electronics system or its components, or shutting down components or systems when overheating is detected. Figure for the abstract: [Fig 2]

Description

Title of the invention: TEMPERATURE ESTIMATION FOR POWER ELECTRONICS Technological background

[0001] In power electronics such as inverters, control devices for systems including electric motors, and the like, temperatures can be monitored using embedded temperature sensors. Such monitoring can be used to provide protection against excessive temperature and / or to compensate for the effects of temperature on electronic performance. Embedded temperature sensors can be difficult to implement and may increase cost, power consumption, or board size. Such temperature sensors can also constitute an additional point of failure, reducing mean time between component failures and making component certification more difficult for applications such as aerospace applications.In the absence of such temperature sensors, cooling systems may operate at fixed values ​​to prevent overheating, which can cause unnecessary wear on components such as cooling fans. Summary

[0002] This disclosure relates to temperature monitoring in power electronic systems, in particular using models to calculate temperatures based on system operating conditions.

[0003] Temperature monitoring according to the embodiments described herein can enable temperature determination even in systems that do not include onboard temperature sensors. This can allow for more precise cooling control and / or corrective actions such as shutting down components when overheating conditions are detected. Temperature monitoring according to these embodiments can provide temperature response capabilities without the cost, complexity, or space requirements of onboard temperature sensors.In some embodiments, temperature monitoring can be used in addition to temperature sensors such as on-board temperature sensors, separate temperature sensors such as resistance temperature detectors or negative temperature coefficient thermistors, or the like, to provide redundancy and / or to provide knowledge of temperature conditions in areas where temperature sensors cannot be provided.

[0004] In one embodiment, temperature monitoring can be used to control cooling systems in order to reduce wear on these cooling systems, for example, by regulating fan speeds when temperatures are within acceptable ranges. Reducing wear on cooling systems can increase the mean time between failures (MTBF) for a reliability-critical component, thereby increasing the MTBF for an entire device where cooling systems are a limiting factor for reliability.

[0005] In one embodiment, a temperature monitoring system includes one or more processors and one or more memories. The one or more memories store instructions which, when executed, cause the one or more processors to receive operational characteristics of a power electronics system. The instructions further cause the one or more processors to determine, based on the operational characteristics and a model of the power electronics system, an estimated power loss for the power electronics system.The instructions also instruct one or more processors to determine, based on the estimated power loss and a thermal model of the power electronics system, at least one temperature associated with the power electronics system, including either an air temperature inside a power electronics system enclosure or a junction temperature within the power electronics system. The instructions further instruct one or more processors to control the operation of the power electronics system based on at least one temperature.

[0006] In one embodiment, a temperature monitoring method includes receiving, at the processor level, the operational characteristics of a power electronics system. The method further includes determining, based on the operational characteristics and a model of the power electronics system, an estimated power loss for the power electronics system. The method also includes determining, based on the estimated power loss and a thermal model of the power electronics system, at least one temperature associated with the power electronics system, including at least one temperature that is either an air temperature inside a housing of the power electronics system or a junction temperature inside the power electronics system.The process also includes controlling the operation of the power electronics system based on at least one temperature.

[0007] A variety of additional inventive aspects will be set forth in the following description. The inventive aspects may relate to individual features and combinations of features. It should be understood that the preceding general description and the detailed description that follows are merely examples and explanations and are not exhaustive of the general inventive concepts on which the embodiments disclosed herein are based. Brief description of the drawings

[0008] The accompanying drawings, which are incorporated into and form part of the description, illustrate several aspects of this disclosure. A brief description of the drawings is as follows:

[0009] [Fig. 1] [Fig. 1] represents a flowchart for a temperature monitoring process according to one embodiment.

[0010] [Fig ] [Fig.2] represents a diagram of a power electronics system according to one embodiment.

[0011] [Fig.3] [Fig.3] represents logic components of a temperature monitoring system according to one embodiment. Detailed description

[0012] We will now refer in detail to exemplary aspects of this disclosure which are illustrated in the accompanying drawings. Where possible, the same numerical references will be used throughout the drawings to designate identical or similar parts.

[0013] Temperature monitoring according to the embodiments described herein can enable the determination of temperatures even in the absence of temperature sensors in the device. Temperature determinations can enable system control, such as the control of cooling systems, the triggering of corrective actions such as a shutdown in response to overheating conditions, the compensation of temperature effects, or the like. In one embodiment, temperature monitoring can be used to determine junction temperatures affecting performance in power electronics.Temperature monitoring can be used to control cooling systems to limit wear. One example of such control is regulating fans when temperature conditions permit, thereby increasing the overall MTBF by reducing the operating intensity of a reliability-critical component. Temperature monitoring can be determined based on known operating characteristics, thus eliminating the need for additional sensors to provide inputs for temperature estimation.

[0014] Figure 1 shows a flowchart for a temperature monitoring method according to one embodiment. The method 100 includes receiving operational characteristics from a power electronics system 102, determining an estimated power loss based on the operational characteristics using a power electronics model 104, determining a temperature based on the estimated power loss using a thermal model 106, and controlling the operation of the power electronics system 108. Optionally, the method 100 may include deducing at least some of the operational characteristics based on an engine performance model 110.

[0015] The method 100 is a method for determining a temperature based on the operational characteristics of a power electronics system, such as a compressor, a pump, a hydraulic power unit, an electrically powered traction motor, or the like. The method 100 can be implemented using a control device included in the system, such as the control device 208 of the power electronics system 200 as described below and illustrated in [Fig. 2]. In some embodiments, the method 100 can be run continuously to monitor temperatures, or run at predetermined sampling intervals.In one embodiment, the method 100 may include feedback between steps, such as providing cooling system data like fan speeds as input to the thermal model when controlling the operation of the power electronics system at 108 includes adjusting the operation of a cooling system.

[0016] The operational characteristics of a power electronics system are received in 102. The operational characteristics may be conditions relevant to the demand on the power electronics system. For example, in an embodiment in which the power electronics system is an electrically powered hydraulic power unit, the operational characteristics may include a flow demand from the hydraulic power unit, an ambient pressure in the environment around the hydraulic power unit, and a bay temperature of the hydraulic power unit.In one embodiment, the operational characteristics may include a volume or power demand for a pump or compressor, a power demand for an electrically powered traction motor or actuator, power consumption from an inverter or uninterruptible power supply (UPS), or the like. In one embodiment, the operational characteristics include a controlled operating point of an electric motor. In one embodiment, the... Operational characteristics may include the current consumption of an electric motor and the voltage applied to said electric motor. In one embodiment, the operational characteristics received in 102 can be deduced in 110 using a motor performance model.

[0017] An estimated power loss is determined based on the operational characteristics using a power electronics model in 104. The power electronics model is a mathematical model configured to calculate the estimated power loss based on the operational characteristics received in 102. The power electronics model may be a model determined based on a test of the power electronics system, simulations, a finite element analysis (FEA), component characteristics known, for example, from manufacturer datasheets, combinations thereof, or the like. The power electronics model may be a static model that is determined in advance and stored in a memory of a control device implementing the method 100 in a power electronics system.The estimated power loss is an estimate of the power that will be consumed in the power electronics system, for example, due to circuit components within it such as resistors, transistors such as metal-oxide-semiconductor field-effect transistors (MOSFETs), diodes, combinations thereof, and the like. In one embodiment, the power electronics model can accept a junction temperature as an input and be configured to take the junction temperature into account when determining the estimated power loss.The junction temperature can be a junction temperature as determined by the thermal model on the basis of the power loss in 108 previously determined according to process 100, for example the most recent junction temperature in continuous monitoring, a junction temperature as determined in a previous iteration of process 100, or similar.

[0018] One or more temperatures are determined based on the estimated power loss in 106. The estimated power loss can be the output from the power electronics model determined in 104. The one or more temperatures are determined in 106 based on a thermal model. The thermal model can be a predictive thermal model, such as a model generated by computational fluid dynamics (CFD), a one-dimensional (1-D) thermal model, a thermal model generated by finite element analysis (FEA), or similar. In one embodiment, the thermal model is the 1-D thermal model. The thermal model can be a predetermined model stored in a memory of the control device. The thermal model can determine, based on the power loss estimated, the heat generation in the power electronics system. The heat generation can in turn be used by the thermal model to deduce temperatures in the power electronics system, for example on the basis of, for example, a known or assumed heat generation and / or dissipation from components, housings and the like, cooling of the power electronics system such as airflows driven by cooling fans, other airflows, other heat transfers occurring in the device or system, and the like.The temperatures determined in 106 include one or more temperatures associated with the power electronics system, such as, for example, a temperature of a housing of the power electronics system, one or more junction temperatures of junctions in the power electronics system, a temperature of airtight seals in the power electronics system, or the like.

[0019] In one embodiment, the method 100 includes controlling the operation of the power electronics system in 108. The control of the operation of the power electronics system in 108 is based on one or more of the temperatures determined in 106. A non-limiting example of controlling the operation of the power electronics system in 108 is shutting down one or more components of the power electronics system in response to one or more temperatures exceeding a threshold indicative of an overheating condition. Another non-limiting example of controlling the power electronics system in 108 is controlling one or more components based on a junction temperature determined in 106 to account for performance changes associated with the junction temperature.

[0020] In the example illustrated in [Fig. 1], the control of the operation of the power electronics system in 108 includes determining the cooling demand 112 and adjusting the cooling based on the cooling demand 114. The determination of the cooling demand in 112 can be based on one or more of the temperatures determined in 106, for example, by comparing one or more temperatures to one or more thresholds, using a formula that accepts one or more temperatures as input, referring to a lookup table, or similar methods. The cooling demand determined in 112 can indicate the cooling requirement to maintain acceptable temperatures in the power electronics system, or at the level of one or more components thereof. The cooling can be adjusted in 114 based on the cooling demand.Adjusting the cooling in 114 can be, for example, reducing the speed of one or more cooling fans in a cooling system, or disabling one or more fans. cooling, or similar methods, to meet the cooling demand while reducing excess cooling capacity. In one embodiment, the cooling adjustment in 114 is a regulation of fan speeds, thereby reducing wear resulting from fan operation at full speed. The operating parameters of the cooling system after adjusting the operations in 114 can be provided as input to the thermal model for future iterations of the process 100, for example, by providing a fan flow rate to the thermal model such that the current operations of the cooling system are correctly represented in the thermal system when determining temperatures in 106.

[0021] Optionally, the method 100 may include the deduction of at least some of the operating characteristics based on a motor performance model 110. For example, a motor performance model may be used to deduce one or more of the following: a motor current, a voltage applied to the motor, or the like, based on one or more inputs such as motor speed, ambient temperature, a junction temperature determined in 108, combinations thereof, and the like. The motor performance model may be deduced, by way of non-limiting examples, from empirical testing of motors, motor design and component selection, published motor characteristics such as manufacturer data sheets, motor performance simulations, combinations thereof, or the like.The engine performance model can be a predetermined model stored in a memory of the control device implementation process 100.

[0022] Figure 2 represents a schematic diagram of a power electronics system according to a embodiment. The power electronics system 200 includes a power supply 202, an inverter 204, a motor 206, and a control device 208. In one embodiment, one or more temperature sensors 210 may be provided in the power electronics system 200. In one embodiment, the power electronics system 200 includes a cooling system 212, the cooling system 212 including fans 214.

[0023] The power electronics system 200 is a device including an electrically powered motor 206 supplied by a power source 202. Non-limiting examples of such a power electronics system 200 include electric pumps such as fuel or hydraulic pumps, compressors, actuators such as control surface actuators for aerospace applications, electric traction motors, or the like. In one embodiment, the power electronics system 200 is an electrically powered hydraulic power unit.

[0024] The power supply 202 is a power supply for the power electronics system 200. The power supply 202 can be, for example, one or more batteries. The power supply 202 can be a direct current (DC) power supply. The power supply 202 can be configured to provide sufficient voltage and current to the inverter 204 so that the alternating current (AC) power output of the inverter 204 is sufficient to drive the motor 206. The inverter 204 is configured to receive DC power from the power supply 202 and output an appropriate AC power supply to drive the operation of the motor 206. The motor 206 is an electric motor powered by the AC power output of the inverter 204.The motor 206 can drive the operation of the power electronics system 200, for example drive a pump, compressor or actuator, by providing motive force from an electric traction motor, or similar.

[0025] The control device 208 is configured to control the operation of one or more of the following: the power supply 202, the inverter 204, the drive motor 206 and / or the cooling system 212. The control device 208 can be configured to receive operational characteristic inputs from the power electronics system 200. The control device 208 includes one or more processors 216 and one or more memories 218. The one or more memories 218 are configured to store program instructions and models to perform temperature monitoring, for example, the power electronics mode, the thermal model, and instructions directing the performance, for example, of the process 100 as described above and shown in [Fig. 1].The one or more memories 218 may further include program instructions to control operations in response to a determined temperature, for example, to control an inverter 204 and / or a drive motor 206 to adjust or cease operations based on the determined temperature, to control a cooling system 212 or its fans 214, or the like. In one embodiment, the one or more memories 218 include program instructions controlling the speed of the fans 214 based on the determined temperature, so as to operate the fans at levels sufficient to maintain appropriate temperatures without providing excessive cooling.

[0026] In an optional embodiment, one or more temperature sensors 210 may be included in the power electronics system 200, for example at or on a printed circuit board of the inverter 204, at or near the power supply 202, at or near the motor 206, on or inside a housing containing at least some components of the power electronics system 200, or similar components. The temperature sensors 210 can be connected to the control device 208 to provide temperature readings from their respective locations. In another embodiment, no temperature sensor 210 is included in the power electronics system 200. In one embodiment, no temperature sensor 210 is provided on the circuit boards included in the power supply 202, the inverter 204, and / or the motor 206 included in the power electronics system 200.

[0027] When the optional temperature sensors 210 are included, the control device 208 can further be configured to control operations of the power electronics system 200 based on readings from the temperature sensors 210. In one embodiment, the readings from the temperature sensors 210 can be used for at least some of the same temperatures as those determined at the control device 208, thus providing redundancy. In one embodiment, the temperature sensors 210 can serve as a backup for temperature determination by the control device 208. In one embodiment, temperature determinations at the control device 208 can serve as a backup for the temperature sensors 210.Such redundancy allows the power electronics system 200 to continue operating even if one or more of the temperature sensors 210 fail. In one embodiment, at least some of the temperature sensors 210 can measure temperatures not determined by the control device 208, thus providing additional temperature data. This additional temperature data can be used by the control device 208 when controlling one or more components of the power electronics system 200. In another embodiment, both the additional temperature data and the temperatures determined by the control device 208 can be used to control elements of the power electronics system 200.

[0028] In the embodiment illustrated in [Fig. 2], the power electronics system 200 includes a cooling system 212. The cooling system 212 is configured to provide cooling to at least some components of the power electronics system 200. The cooling system may be, for example, an air cooling system configured to direct a flow of cooling air through a housing of the power electronics system, or a fluid cooling system configured to circulate a cooling fluid to one or more components of the power electronics system. of power 200, or similar. The cooling system may include one or more fans 214 configured to drive an airflow, for example, to provide cooling airflow, to direct airflows over a radiator for the cooling fluid, or similar. In one embodiment, the fans 214 may be controlled by the control device 208 based on predetermined or measured temperatures.In one embodiment, the control device 208 can control the cooling system 212 to match the cooling demand indicated by the temperatures inside the power electronics system 200, for example, by reducing the cooling provided by the cooling system 212 to match the cooling demand indicated by the temperatures determined at the control device 208 and / or the temperatures received from optional temperature sensors 210. For example, the speed of the fans 214 can be reduced when the cooling capacity of the cooling system 212 is not fully required to maintain appropriate temperatures. The control device 208 can be configured to control other elements of the cooling system 212 on a temperature basis, such as a pump circulating a cooling fluid, or the like.

[0029] Figure 3 represents logic components of a temperature monitoring system according to one embodiment. The logic components of the temperature monitoring system 300 include the power electronics model 302, the thermal model 304, and optionally the motor performance model 306.

[0030] The logic components of the temperature monitoring system 300 are models that can be stored in memories and used by processors of a control device in a power electronics device or system, such as the control device 208 of the power electronics system 200. The models can be stored in one or more memories, such as the memories 218 of the control device 208. The control device 208 can use the models at respective stages when carrying out temperature monitoring, for example according to the method 100 as described above and shown in [Fig. 1].

[0031] The power electronics model 302 is a mathematical model configured to determine power losses in a power electronics system based on the operational characteristics of the power electronics system. The operational characteristics may include voltages and currents in the power electronics system, such as applied voltage, motor current, and the like. The operational characteristics may optionally include parameters indicative of the load on the power electronics system. Such as, for a hydraulic power unit, the flow demand, ambient pressure, and bay temperature as obtained for a given duty cycle of the hydraulic power unit. In one embodiment, the power electronics model 302 can receive such indicative load parameters directly to determine the power loss in the power electronics system. In one embodiment, the optional motor performance model 306 can determine voltages and currents to be input into the power electronics model 302 for determining the power loss, as described below.The power electronics model 302 can be derived from one or more of the following: device performance simulations, datasheets for the device or its components developed by a manufacturer, characteristics of the components and their arrangement in the power electronics system, a finite element analysis, combinations thereof, or the like. In one embodiment, the power electronics model 302 can produce power losses for each of a plurality of circuits provided in a power electronics system based on input operating characteristics. In one embodiment, the power electronics model can accept as inputs one or more junction temperatures determined using the thermal model 304.

[0032] The thermal model 304 is a mathematical model configured to determine one or more temperatures in the power electronics system based on inputs including power losses in the system as determined from the power electronics model 302, and optionally ambient temperatures, the operation of cooling systems, and the like. The temperatures delivered as output by the thermal model 304 can be estimated temperatures for one or more positions or one or more components in the power electronics system, such as a junction temperature in the power electronics system, a temperature at or inside a housing of the power electronics system, a temperature at a circuit board of an inverter, a motor temperature, a power supply temperature such as a battery, or the like. Thermal model 304 can be a predictive thermal model, such as a thermal model generated by FEA or CFD. In one embodiment, thermal model 304 is a 1-D thermal model. Thermal model 304 can be deduced based on characteristics of the power electronics system, such as the known or assumed heat generation and / or dissipation of components, enclosures, and the like, and the cooling of the power electronics system, such as airflow driven by cooling fans, and the like. In one embodiment, the thermal model 304 can accept operational characteristics of a cooling system, such as fan speed, delivered cooling capacity, or the like, as input. In one embodiment, the operational characteristics of the cooling system can be provided from a control device directing the operation of the cooling system, such as the control device 208 described above and shown in [Fig. 2].

[0033] The motor performance model 306 may optionally be included among the logic components 300. The motor performance model 306 may be a mathematical model configured to determine appropriate inputs for the power electronics model 302 based on the operation of the power electronics system. For example, when the power electronics model 302 is configured to receive an applied voltage and a motor current as operational parameters used to determine power loss, the motor performance model 306 may be a mathematical model configured to determine the applied voltage and motor current based on the operation of the power electronics system, for example, parameters indicative of the power electronics system load.In an example where the power electronics system is a hydraulic power unit, the motor performance model can be configured to determine the operating characteristics entered into the power electronics model 302 based on parameters such as flow demand, ambient pressure, and bay temperature as obtained for a given duty cycle of the hydraulic power unit. The motor performance model 306 can be derived based on, for example, models and / or simulations of the performance of the power electronics system or its components, manufacturer datasheets, or other sources of knowledge concerning the characteristics of particular components, the selection and arrangement of components in the power electronics system, combinations thereof, and the like. Aspects of disclosure:

[0034] It is understood that one of the aspects 1 to 10 described below can be combined with one of the other aspects 11 to 20.

[0035] Aspect 1 relates to a temperature monitoring system, comprising: one or more processors; and one or more memories, the one or more memories storing instructions which, when executed, cause the one or more processors to: receive operational characteristics from a power electronics system; to determine, based on the operational characteristics and a model of the power electronics system, an estimated power loss for the power electronics system, determine, based on the estimated power loss and a thermal model of the power electronics system, at least one temperature associated with the power electronics system, including at least one temperature encompassing an air temperature inside a power electronics system enclosure or a junction temperature inside the power electronics system; and control the operation of the power electronics system based on at least one temperature.

[0036] Aspect 2 relates to a temperature monitoring system according to aspect 1, in which the thermal model is a one-dimensional heat transfer model.

[0037] Aspect 3 relates to a temperature monitoring system according to aspect 1 or aspect 2, wherein the instructions further cause one or more processors to determine at least some of the operational characteristics of the power electronics system on the basis of a received ambient temperature, a received motor speed and a motor performance model.

[0038] Aspect 4 relates to a temperature monitoring system according to any one of aspects 1 to 3, in which the instructions cause one or more processors to control the operation of the power electronics system by directing the deactivation of the power electronics system.

[0039] Aspect 5 relates to a power electronics system including the temperature monitoring system according to any one of aspects 1 to 4.

[0040] Aspect 6 relates to a power electronics system according to aspect 5, further comprising one or more fans, in which one or more processors are configured to control the operation of the power electronics system by adjusting an operating speed of at least one of the one or more fans.

[0041] Aspect 7 relates to a power electronics system according to aspect 5 or aspect 6, in which the power electronics system is a hydraulic power unit comprising a power source, an inverter and a motor.

[0042] Aspect 8 relates to a power electronics system according to aspect 7, in which the operational characteristics include a flow demand, an ambient pressure and a bay temperature for the hydraulic power unit.

[0043] Aspect 9 relates to a power electronics system according to any one of aspects 1 to 8, further comprising one or more temperature sensors.

[0044] Aspect 10 relates to a power electronics system according to any one of aspects 1 to 8, in which the power electronics system does not include a temperature sensor.

[0045] Aspect 11 relates to a temperature monitoring method, comprising the steps of: to receive, at the level of a processor, the operational characteristics of a power electronics system; to determine, based on the operational characteristics and a model of the power electronics system, an estimated power loss for the power electronics system determine, based on the estimated power loss and a thermal model of the power electronics system, at least one temperature associated with the power electronics system, including at least one temperature encompassing an air temperature inside a power electronics system enclosure or a junction temperature inside the power electronics system; and control the operation of the power electronics system based on at least one temperature.

[0046] Aspect 12 relates to a method according to aspect 11, in which the control of the operation of the power electronics system on the basis of at least one temperature includes the control of one or more cooling fans of the power electronics system.

[0047] Aspect 13 relates to a method according to aspect 12, in which the control of one or more of the cooling fans includes reducing the speed of at least one of the one or more cooling fans.

[0048] Aspect 14 relates to a method according to any one of aspects 11 to 13, wherein the control of the operation of the power electronics system includes the deactivation of the power electronics system.

[0049] Aspect 15 relates to a method according to any one of aspects 11 to 14, in which the thermal model of the power electronics system is a one-dimensional heat transfer model.

[0050] Aspect 16 relates to a method according to any one of aspects 11 to 15, further comprising the determination of the operational characteristics of the power electronics system on the basis of an engine speed, an ambient temperature and an engine performance model.

[0051] Aspect 17 relates to a method according to aspect 16, in which the operational characteristics of the power electronics system include a current supplied to a motor and an applied voltage.

[0052] Aspect 18 relates to a method according to any one of aspects 11 to 17, wherein the operational characteristics of the power electronics system include the junction temperature.

[0053] Aspect 19 relates to a method according to any one of aspects 11 to 18, further comprising the detection of at least one temperature in the power electronics system using at least one temperature sensor.

[0054] Aspect 20 relates to a method according to any one of aspects 11 to 18, in which the power electronics system does not include a temperature sensor.

[0055] Having described the preferred aspects and implementations of this disclosure, modifications and equivalents of the disclosed concepts may readily be apparent to a person skilled in the art. However, it is intended that these modifications and equivalents will be included within the scope of the claims annexed hereto.

Claims

Demands

1. A temperature monitoring system, comprising: one or more processors; and one or more memories, the one or more memories storing instructions which, when executed, cause the one or more processors to: - receive operational characteristics from a power electronics system; - determine, based on the operational characteristics and a model of the power electronics system, an estimated power loss for the power electronics system; - determine, based on the estimated power loss and a thermal model of the power electronics system, at least one temperature associated with the power electronics system, at least one temperature including an air temperature inside a housing of the power electronics system or a junction temperature inside the power electronics system;and - control the operation of the power electronics system based on at least one temperature.

2. Temperature monitoring system according to claim 1, wherein the thermal model is a one-dimensional heat transfer model.

3. Temperature monitoring system according to claim 1 or 2, wherein the instructions further cause one or more processors to determine at least some of the operational characteristics of the power electronics system on the basis of a received ambient temperature, a received motor speed and a motor performance model.

4. Temperature monitoring system according to any one of claims 1 to 3, wherein the instructions cause one or more processors to control the operation of the power electronics system by directing the deactivation of the power electronics system.

5. Power electronics system including temperature monitoring system according to any one of claims 1 to 4.

6. Power electronics system according to claim 5, further comprising one or more fans, wherein one or more processors are configured to control the operation of the power electronics system by adjusting an operating speed of at least one of the one or more fans.

7. Power electronics system according to claim 5 or 6, wherein the power electronics system is a hydraulic power unit comprising a power source, an inverter and a motor.

8. Power electronics system according to claim 7, wherein the operational characteristics include a flow demand, an ambient pressure and a bay temperature for the hydraulic power unit.

9. Power electronics system according to any one of claims 5 to 8, further comprising one or more temperature sensors.

10. Power electronics system according to any one of claims 5 to 9, wherein the power electronics system does not include a temperature sensor.

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