Monitoring device for a cooling device

Abstract

Monitoring device (20) for monitoring a cooling device (14) for a power electronics arrangement (12), which monitoring device (20) has a control device (22), which control device (22) has an input (24) and an output (26), which input (24) is configured to receive a temperature signal (17) from a temperature sensor (16) and to determine a temperature value (Temp1, Temp2) depending on the temperature signal (17), which output (26) is configured to output a signal (27), and which control device (22) is configured to perform the following steps: - A temperature value (Temp1, Temp2) and a time value (t1, t2) associated with the temperature value are determined at least twice. - A difference quotient (DQ) of the change in temperature values ​​(Temp1, Temp2) to the change in the associated time values ​​(t1, t2) is determined. - Depending on the determined difference quotient (DQ), the state (STATE) of the cooling device (14) of the power electronics arrangement (12) is determined, and depending on the state (STATE), the output signal (27) is output to influence the power electronics arrangement (12), which monitoring device (20) has a first predetermined difference quotient (DQ1) which characterizes a first fault state (S_ERR_1) of the cooling device (14), and which monitoring device (20) uses as a condition for the assumption of the first fault state (S_ERR_1) of the cooling device (14) the criterion that the determined difference quotient (DQ) is greater than the first predetermined difference quotient (DQ1).

Description

[0001] The invention relates to a monitoring device for a cooling device. The cooling device is particularly suitable for a power electronics assembly.

[0002] Power electronics devices such as DC / DC converters and AC / DC converters transform an electrical voltage into a different electrical voltage and are used, for example, to charge a high-voltage battery or to convert the voltage between a vehicle's high-voltage electrical system and its low-voltage electrical system. These power electronics devices sometimes operate at power levels of, for example, 11 kW or 22 kW, resulting in heat losses that must be dissipated by a cooling system. At high power levels, cooling with a coolant, especially a liquid, is necessary. The automotive industry is developing solutions for highly automated driving, and this is increasing the demands on the reliability of electronic components. Standards such as ASIL D (Automotive Safety Integrity Level D) impose strict requirements, such as the need for redundant design and separate development for a component to enhance safety.As part of this discussion, the idea is to implement a redundant low-voltage battery (e.g., 12 V or 24 V) for the vehicle's electrical system. This would ensure that the driver still has functioning steering and can, for example, pull into a lay-by if one battery fails. Using two batteries would result in significant weight, and redundancy could also be achieved with a DC / DC converter that generates the required low voltage from a high-voltage battery used for propulsion. However, this requires adequate cooling to provide sufficient power. For successful implementation, it is advantageous to have reliable detection of the cooling system's proper functioning.

[0003] The US 2012 / 0 199 084 A1, US 5,215,044 A and the EP 2 494 162 B1 show a cooling system with multiple temperature sensors for a vehicle with an internal combustion engine or hybrid drive.

[0004] US 2012 / 0262881A1 describes a procedure for verifying the presence of a sufficient quantity of refrigerant in the liquid phase. If this is the case, a compressor and a cooling fan are switched off.

[0005] US Patent 2013 / 0069591A1 discloses a method for controlling a cooling system for a vehicle charger depending on several temperature sensors.

[0006] DE 10 2011 076 908 A1 discloses a method for operating an inverter with a temperature monitoring device for recording temperatures on phase systems of the inverter. Temperature gradients are determined from the temperatures, and deviations of the determined temperature gradients from one another are identified, thereby detecting errors.

[0007] It is therefore an object of the invention to provide a new cooling device.

[0008] A monitoring device for monitoring a cooling device for a power electronics arrangement has a control device, which control device has an input and an output, which input is configured to receive a temperature signal from a temperature sensor and to determine a temperature value depending on the temperature signal, which output is configured to output a signal, and which control device is configured to perform the following steps: - A temperature value and a time value associated with the temperature value are determined at least twice. - A difference quotient of the change in temperature values ​​to the change in the associated time values ​​is determined. - Depending on the determined difference quotient, the state of the cooling device of the power electronics arrangement is determined, and depending on the state, the output signal is output to influence the power electronics arrangement.

[0009] Characterizing the state of the cooling device as a function of the difference quotient has proven to be very informative and allows for a comparatively accurate determination of the state.

[0010] According to a preferred embodiment, the monitoring device determines, based on the temporal progression of the temperature values, whether the temperature is in an increasing range or in an asymptotic range, and the monitoring device is designed to store the associated temperature value and the associated time value when transitioning from the increasing range to the asymptotic range and to use these values ​​when forming the difference quotient.

[0011] This allows a measurement to be taken at a predetermined point on the temperature curve, resulting in readily comparable difference quotients.

[0012] According to a preferred embodiment, the monitoring device is designed to determine the transition from the rising region to the asymptotic region by ensuring that the difference quotient is smaller than a predetermined minimum difference quotient.

[0013] This is a simple and well-functioning design that places only minimal demands on the hardware.

[0014] According to a preferred embodiment, the monitoring device is configured to determine the transition from the rising region to the asymptotic region by calculating the maximum difference quotient during the time course and assuming the transition has occurred when the difference quotient is smaller than a predetermined fraction of the maximum difference quotient. This increases the accuracy of transition detection under rapidly changing initial and environmental conditions.

[0015] According to a preferred embodiment, the monitoring device is configured to store the associated temperature value and the associated time value when the power electronics arrangement is activated, and to use these values ​​when forming the difference quotient.

[0016] This allows a measurement to be taken at an early point in the temperature curve, leading to a good estimate of the overall slope.

[0017] According to a preferred embodiment, the monitoring device is configured to determine a time at which the temperature exceeds a predetermined first temperature limit, and the monitoring device is configured to store the corresponding temperature value or the first temperature limit on the one hand and the corresponding time value on the other, and to use these values ​​in calculating the difference quotient. This results in a measurement at a predetermined point on the temperature curve, leading to readily comparable difference quotients.

[0018] According to a preferred embodiment, the monitoring device is designed to repeatedly determine and evaluate the difference quotient of time-spaced temperature measurements. Repeated determination of the current difference quotient allows for a timely response to extreme changes.

[0019] The monitoring device has a first predefined difference quotient, which characterizes a first fault condition of the cooling device. The condition for assuming this first fault condition is that the determined difference quotient is greater than the first predefined difference quotient. It has been shown that if the difference quotient becomes too large, a fault condition can be assumed with a high degree of probability. In particular, a coolant leak leads to a critically rapid temperature increase.

[0020] According to a preferred embodiment, the monitoring device uses, as an additional condition for assuming the first fault condition, the criterion that the current temperature value is greater than a predefined second temperature limit. This allows the absolute temperature to also be taken into account.

[0021] According to a preferred embodiment, the monitoring device is configured to output a termination signal via its output upon detection of the first fault condition of the cooling device, in order to deactivate the power electronics assembly. Deactivation protects the power electronics assembly from damage.

[0022] According to a preferred embodiment, the monitoring device has a second predefined difference quotient, which characterizes a second fault condition of the cooling device. The criterion for assuming a second fault condition of the cooling device is that the determined difference quotient is greater than the second predefined difference quotient. By using the second predefined difference quotient, less severe fault conditions can also be detected and appropriate responses can be taken. The second predefined difference quotient is preferably smaller than the first predefined difference quotient.

[0023] According to a preferred embodiment, the monitoring device uses, as an additional condition for assuming the second fault state of the cooling device, the criterion that the determined difference quotient is smaller than the first predetermined difference quotient. This allows minor fault states to be clearly distinguished from major fault states.

[0024] According to a preferred embodiment, the monitoring device uses, as an additional condition for assuming the second fault condition, the criterion that the current temperature value is greater than a predefined third temperature limit. This also allows further fault conditions to be detected.

[0025] According to a preferred embodiment, the monitoring device is configured to output a reduction signal via its output upon detection of the second fault condition of the cooling device, in order to reduce the maximum power of the power electronics arrangement. The power electronics arrangement can still operate, for example, in emergency mode.

[0026] According to a preferred embodiment, the power electronics arrangement is an AC / DC converter, a DC / AC converter, or a DC / DC converter. With these converters, the monitoring device is particularly advantageous because it provides redundancy, for example, with a vehicle battery in the vehicle's electrical system, thus increasing safety.

[0027] According to a preferred embodiment, the determined difference quotients are at least partially stored, for example extreme difference quotients or difference quotients above a predetermined limit.

[0028] According to a preferred embodiment, a vehicle has such a monitoring device. The monitoring device significantly increases safety.

[0029] Further details and advantageous embodiments of the invention will become apparent from the exemplary embodiments described below and illustrated in the drawings, which are in no way to be understood as limiting the invention, as well as from the dependent claims. The drawings show: Fig. 1. Schematic representation of the overall structure of a vehicle with a power electronics arrangement, a cooling device and a monitoring device, Fig. 2. a temperature profile of a coolant when the cooling device is functioning properly Fig. 3 the temperature profile of the coolant during a first fault condition of the cooling device, Fig. 4. the temperature profile of the coolant during a second fault condition of the cooling device, Fig. 5. an assignment of difference quotients to states, Fig. 6. A flowchart for determining the condition of the cooling device, Fig. 7. A flowchart for determining an initial time value and initial temperature value. Fig. 8 a flowchart for determining a second time value and second temperature value, Fig. 9 an alternative for determining the condition of the cooling device, Fig. 10. Another alternative for determining the condition of the cooling device, and Fig. 11 a flowchart for evaluating the state by the power electronics arrangement.

[0030] Fig. Figure 1 shows a schematic representation of a vehicle 10, e.g., an electric vehicle or a hybrid vehicle. A power electronics assembly 12 is provided, in particular a DC / DC converter, a DC / AC converter, or an AC / DC converter. A cooling device 14 is provided for cooling the power electronics assembly 12, and a temperature sensor 16 is provided on the cooling device 14 to generate a temperature signal 17 depending on the temperature at the cooling device 14 and output it via a data line 18. A monitoring device 20 has a control device 22 with an input IN 24 and an output OUT 26. The power electronics assembly 12 is connected to the input 24 via a data line 13, and the data line 18 is also connected to the input 24. The output 26 is connected to the power electronics assembly 12 via a data line 28 for transmitting a signal 27.The output 26 is also connected to a vehicle computer 30 via a data line 29 to enable the output of an error.

[0031] The control device 22 is designed to evaluate the temperature signal 17 and, depending on this signal, to influence the power electronics assembly 12. Additionally or alternatively, an error signal can be output to the vehicle computer 30. The control device 22 detects whether the cooling device 14 is operating normally or whether a fault has occurred. For example, in a liquid cooling system, the coolant may have leaked from the cooling circuit, or the coolant may not be circulating because, for example, a coolant line is blocked or the pump is malfunctioning.

[0032] Fig. Figure 2 shows the temperature measured by temperature sensor 16, plotted against time. At time t1, the power electronics assembly 12 is activated, and as a result of the power dissipation of the power electronics assembly 12, the temperature of the coolant in the cooling device 14 rises. Depending on the power dissipation of the power electronics assembly 12, a corresponding temperature is established over time. After the activation of the power electronics assembly 12, the temperature profile has a rising phase 41, in which the temperature increases, followed by an asymptotic phase 42, in which the temperature changes only slightly. The cooling device 14 is in a normal state S_Norm, i.e., it is functioning correctly.

[0033] The graph shows time t1, at which the power electronics assembly 12 was activated. At time t2, the transition from the rising region 41 to the asymptotic region 42 takes place. At time t1, the temperature has a value Temp1, and at time t2, a value Temp2. ​​In addition to the temperature profile, the direct slope between the values ​​at times t1 and t2 is also shown. The slope can be calculated from the difference quotients DQ of the temperature values ​​and the time values ​​according to the formula... DQ=ΔTemp / Δt=(Temp2−Temp1) / (t2−t1)

[0034] Fig. Figure 3 shows the temperature profile in a state S_ERR_2 where there is no coolant flow, for example because the coolant pump is defective.

[0035] At time t1, the power electronics assembly 12 is activated again, and at time t2, a transition from the rising region 41 to the asymptotic region 42 takes place. It can be seen that the curve is steeper than in Fig. 2, and a higher temperature Temp2 is reached at time t2. The difference quotient is correspondingly larger than in Fig. 2.

[0036] Fig. Figure 4 shows the temperature profile for a state S_ERR_1 in which the cooling device 14 has lost coolant, thus severely impairing cooling. At time t1, the power electronics assembly 12 is activated, and at time t2, a transition from the rising region 41 to the asymptotic region 42 takes place: The slope between times t1 and t2 is even steeper than in Figure 4. Fig. 3 and Fig. 2, and thus the difference quotient DQ is also in Fig. 4 larger than in Fig. 3 and in Fig. 2.

[0037] Tests have shown that the state of the cooling device 14 can be accurately determined by calculating the difference quotient DQ.

[0038] Fig. Figure 5 shows an assignment of the difference quotient DQ to different states of the cooling device 10. Above a first predefined difference quotient DQ1, and thus at a very steep slope of the temperature profile, it is assumed that the cooling device 14 is in a state S_ERR_1, in which a serious fault exists, e.g., a loss of coolant. Between the first predefined difference quotient DQ1 and a second predefined difference quotient DQ2, and thus at a lower but still steep slope, it is assumed that a state S_ERR_2 exists, in which the cooling device 14 has some cooling capacity, but not its full cooling capacity. This can be the case, for example, if the coolant pump is not functioning. If the difference quotient DQ is smaller than the predefined second difference quotient DQ2, it can be assumed that the cooling device 14 is functioning normally and is in a state S_NORM.Alternatively, an additional third predefined difference quotient DQ3 can be provided, and it can be assumed that if the difference quotient DQ is smaller than the third difference quotient DQ3, something is wrong with the cooling device 14 or with the temperature sensor.

[0039] The determined state can be output to the power electronics assembly 12 and / or the vehicle computer 30, which can then react accordingly. For example, the power electronics assembly 12 can deactivate itself in state S_ERR_1, as damage to the assembly could occur without cooling. In states S_ERR_2 and S_ERR_3, the power electronics assembly 12 can react, for example, by reducing its maximum power output. If the power electronics assembly 12 is, for example, a DC / DC converter, the maximum output power can be reduced from 10 kW to 4 kW. In state S_ERR_3, the vehicle computer 30 can react, for example, by prompting the vehicle to visit a workshop.

[0040] The parameters DQ1, DQ2, DQ3, and the other parameters used in the calculations depend on the specific cooling device and the power electronics arrangement. For new production runs, for example, trial measurements with the corresponding errors can be carried out, and suitable parameters can be determined accordingly. These parameters can then be stored in non-volatile memory in the monitoring device 20, for example, for the relevant application.

[0041] Fig. Figure 6 shows a flowchart for a routine for evaluating the difference quotient DQ. The process starts in S100, for example, when the power electronics assembly 12 is activated. In S102, a first time value t1 and a first temperature value Temp1 are determined. Subsequently, in S104, a second time value t2 and a second temperature value Temp2 are determined. In S106, the difference quotient DQ is calculated using formula (1).

[0042] In S108, it is checked whether the difference quotient DQ is greater than the first predefined difference quotient DQ1. If so, the state STATE in S110 is set to the value S_ERR_1. If not, a jump is made to S112, where it is checked whether the difference quotient DQ is greater than the predefined second difference quotient DQ2. If so, the state STATE in S114 is set to the value S_ERR_2. If not, a jump is made to S116, where it is checked whether the difference quotient DQ is greater than the predefined third difference quotient DQ3. If so, the state STATE in S118 is set to the value S_NORM. If not, a jump is made to S120, and the state STATE is set to the value S_ERR_3. A jump then occurs to S122, as well as from S110, S114, and S118. In S122, the state STATE is output, e.g. to the vehicle computer 30 or to the power electronics assembly 12. In S124, the routine is terminated.

[0043] Routine S100 can naturally be executed repeatedly by continuously performing steps S102 and S104, thus taking measurements, and then evaluating the current difference quotients DQ in the following steps. If the determination of the difference quotient DQ is also performed in the asymptotic range, the check in S116 can be replaced by step S118, and steps S116 and S120 can be removed to prevent the generation of an error state S_ERR_3 in the asymptotic range 42.

[0044] Fig. Figure 7 shows a possible implementation example for the routine GET t1, Temp1 S102. In S132, a current time value t and a current temperature value Temp are determined or measured ("MEAS"). In S134, it is checked whether the temperature value Temp is greater than or equal to a temperature limit Temp_lim_1, i.e., whether a specific temperature has already been reached. If not, the routine jumps back to S132, and the temperature is determined again. If so, the routine jumps to S136, and the variable t1 is set to the time value t, and the variable temp1 is set to the temperature value Temp. The routine then terminates in S138. The temperature limit Temp_lim_1 can, for example, be set to 30 °C, and the difference quotient DQ can thus be calculated using a point where the same temperature is always present. This allows for good comparability of the evaluation.

[0045] Fig. Figure 8 shows an example implementation of the routine GET t2, Temp2 S104 from Fig. 6. In S142, a time value t and a temperature value Temp are measured, and the measured values ​​are stored in the variables t_OLD and Temp_OLD. In S144, the system waits, and in S146, a time value and a temperature value are similarly stored in the variables t_NEW and Temp_NEW. In S148, the difference quotient DQ is calculated, and in S159, it is checked whether the difference quotient DQ is less than a minimum threshold DQ_min. If this is not the case, meaning the slope of the temperature curve is still relatively large, the system jumps to S152, sets the variable t_OLD to the value of the variable t_NEW, sets the variable Temp_OLD to the value of the variable Temp_NEW, and then jumps back to S144 to calculate the next difference quotient.However, if the difference quotient DQ in S150 is less than the limit value DQ_MIN, a jump to S154 occurs, and the variable t2 is set to the value t_NEW, the variable Temp2 is set to the value Temp_NEW, and a jump to S156 occurs to terminate the routine. The check in S150 determines whether the asymptotic range 42 with a lower slope has already been reached. This allows the time value t2 to be adjusted accordingly. Fig. 2 to Fig. 4 will be determined.

[0046] Alternatively, the transition from the ascending region 41 to the asymptotic region 42 can be determined by calculating the maximum difference quotient DQmax during the time course. This can be done, for example, by continuously storing the previously maximum value DQmax, and replacing it when the difference quotient becomes larger than the previous DQmax. The transition is then assumed when the difference quotient DQ is smaller than a predefined fraction of the maximum difference quotient DQmax, for example, less than 5% of DQmax or less than 10% of DQmax.

[0047] Fig. Figure 9 shows an alternative embodiment of step S108 of Fig. 6. In step S108', as an additional error condition for state S_ERR_1, the evaluation of the difference quotient DQ assesses whether the temperature Temp2, i.e., the current temperature, is greater than a predefined second temperature limit Temp_max_high. It is therefore assumed that an error occurs if this second temperature limit is exceeded. Depending on the application, the two conditions (difference quotient and maximum temperature) can also be used as necessary prerequisites by replacing the OR operation with an AND operation.

[0048] Fig. 10 shows accordingly Fig. 9 an alternative embodiment of step S112 of Fig. 6, in which, in addition to evaluating the difference quotient DQ, the error state S_ERR_2 is also triggered if the current temperature (Temp2) is greater than a predefined third temperature limit Temp_max_mid. Here, too, an AND operation is possible as an alternative.

[0049] Fig.Figure 11 shows a schematic representation of the response of the power electronics assembly 12 to the transmitted state. In S116, the routine starts, and in S162, it is checked whether the state STATE corresponds to state S_ERR_1. If YES, the power electronics assembly 12 is switched off in S164. If NO, in S166, it is checked whether the state STATE corresponds to state S_ERR_2 or state S_ERR_3. If YES, in S168, the maximum power P_max is reduced, but the power electronics assembly 12 remains switched on. If NO, a step to S170 is performed, and it is checked whether the state corresponds to state S_Norm. If YES, the power electronics assembly 12 remains switched on normally ("ON"). If NO, an unknown state exists, and error handling ("ERROR") takes place in S174.

[0050] When comparing "less than" or "greater than", this always includes "less than or equal to" or "greater than or equal to", since for discrete values ​​(e.g., integers) x < y corresponds to x <= (y-1). Reference symbol list 10 vehicles 12 Power electronics arrangement 14 Cooling device 16 Temperature sensor 17 Temperature signal 18 data lines 20 Monitoring device 22 Control device 24 Entrance 26 Exit 27 Output signal 28 data lines 29 Data line 30 vehicle computers 41 Ascent range 42 asymptotic range Temp1, Temp2 temperature value t1, t2 Time DQ Difference Quotient DQ1 given first difference quotient DQ2 given second difference quotient DQ_min limit value for determining the asymptotic range DQ_max maximum difference quotient at measurement

Claims

[1] Monitoring device (20) for monitoring a cooling device (14) for a power electronics arrangement (12), which monitoring device (20) has a control device (22), which control device (22) has an input (24) and an output (26), which input (24) is configured to receive a temperature signal (17) from a temperature sensor (16) and to determine a temperature value (Temp1, Temp2) depending on the temperature signal (17), which output (26) is configured to output a signal (27), and which control device (22) is configured to perform the following steps: - A temperature value (Temp1, Temp2) and a time value (t1, t2) associated with the temperature value are determined at least twice. - A difference quotient (DQ) of the change in temperature values ​​(Temp1, Temp2) to the change in the associated time values ​​(t1, t2) is determined. - Depending on the determined difference quotient (DQ), the state (STATE) of the cooling device (14) of the power electronics arrangement (12) is determined, and depending on the state (STATE), the output signal (27) is output to influence the power electronics arrangement (12), which monitoring device (20) has a first predetermined difference quotient (DQ1) which characterizes a first fault state (S_ERR_1) of the cooling device (14), and which monitoring device (20) uses as a condition for the assumption of the first fault state (S_ERR_1) of the cooling device (14) the criterion that the determined difference quotient (DQ) is greater than the first predetermined difference quotient (DQ1). [2] Monitoring device (20) according to claim 1, which determines, based on the temporal progression of the temperature values ​​(Temp1, Temp2), whether the temperature is in an increasing range (41) or in an asymptotic range (42), and which is configured to store the associated temperature value (Temp1, Temp2) and the associated time value when transitioning from the increasing range (41) to the asymptotic range (42) and to use these values ​​when forming the difference quotient (DQ). [3] Monitoring device (20) according to claim 2, which is configured to determine the transition from the rising region (41) to the asymptotic region (42) by ensuring that the difference quotient (DQ) is smaller than a predetermined minimum difference quotient (DQ_min). [4] Monitoring device (20) according to claim 2, which is configured to determine the transition from the rising region (41) to the asymptotic region (42) by determining the maximum difference quotient (DQmax) during the time course and assuming the transition when the difference quotient (DQ) is smaller than a predetermined proportion of the maximum difference quotient (DQmax). [5] Monitoring device (20) according to one of the preceding claims, which is configured to store the associated temperature value (Temp1) and the associated time value (t1) when the power electronics arrangement (12) is activated and to use these values ​​in the formation of the difference quotient (DQ). [6] Monitoring device (20) according to one of the preceding claims, which is configured to determine a time (t1) at which the temperature value (Temp) exceeds a predetermined first temperature limit (Temp_lim_1), and which is configured to store the associated temperature value (Temp1) or the first temperature limit (Temp_lim_1) on the one hand and the associated time value (t1) on the other and to use these values ​​when forming the difference quotient (DQ). [7] Monitoring device (20) according to one of the preceding claims, which is configured to repeatedly determine and evaluate the difference quotient (DQ) of time-spaced temperature measurements (Temp1, Temp2). [8] Monitoring device (20) according to one of the preceding claims, which uses as an additional condition for the assumption of the first fault state (S_ERR_1) the criterion that the current temperature value (Temp) is greater than a predetermined second temperature limit value (Temp_max_high). [9] Monitoring device (20) according to one of the preceding claims, which is configured to output a termination signal via the output (26) upon detection of the first fault condition (S_ERR_1) of the cooling device (14) in order to deactivate the power electronics arrangement (12). [10] Monitoring device (20) according to one of the preceding claims, which has a second predetermined difference quotient (DQ2) which characterizes a second fault state (S_ERR_2) of the cooling device (14), and which uses as a condition for the assumption of the second fault state (S_ERR_2) of the cooling device (14) the criterion that the determined difference quotient (DQ) is greater than the second predetermined difference quotient (DQ2). [11] Monitoring device (20) according to claim 10 and claim 7, which as an additional condition for the assumption of the second fault state (S_ERR_2) of the cooling device (14) uses the criterion that the determined difference quotient (DQ) is smaller than the first predetermined difference quotient (DQ1). [12] Monitoring device (20) according to claim 10 or 11, which uses as an additional condition for the assumption of the second fault state (S_ERR_2) the criterion that the current temperature value (Temp) is greater than a predetermined third temperature limit value (Temp_max_mid). [13] Monitoring device (20) according to one of claims 10 to 12, which is configured to output a reduction signal via the output (26) when the second fault condition of the cooling device (14) is detected, in order to reduce the maximum power of the power electronics arrangement (12). [14] Monitoring device (20) according to one of the preceding claims, wherein the power electronics arrangement (12) is an AC / DC converter, a DC / AC converter or a DC / DC converter. [15] Vehicle with a monitoring device (20) according to one of the preceding claims.

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