JP5776636B2 - Temperature detection device - Google Patents

Description

  The present invention relates to a temperature detection device that is provided corresponding to each of a plurality of temperature detection targets and includes temperature detection means for detecting the temperature of the temperature detection target.

  Conventionally, as can be seen in Patent Document 1 below, a technique for calibrating a detection value of a temperature sensor that detects the temperature of a predetermined temperature detection target (for example, a semiconductor switching element) is known. This technology will be described. First, data such as detection values of temperature sensors corresponding to different pairs of temperatures are acquired in a manufacturing process of a product incorporating a temperature sensor. Based on the acquired data, calibration data for calibrating the detection value of the temperature sensor is calculated, and the calculated calibration data is stored in a nonvolatile memory mounted on a circuit board in the product.

  According to such a configuration, the detection value of the temperature sensor can be calibrated based on the calibration data stored in the nonvolatile memory. Thereby, the influence which the error contained in the detected value of the temperature sensor has on the grasp of the temperature of the temperature detection target can be suppressed.

JP 2008-197011 A

  Here, after the product is shipped, the calibration data may be lost or the calibration data may not be appropriate data. This occurs, for example, when a product fails and a circuit board on which a non-volatile memory is mounted is replaced at a product repair shop or when the product deteriorates over time. In this case, there is a possibility that the influence of the error included in the detection value of the temperature sensor on the grasp of the temperature of the temperature detection target cannot be suppressed. In order to cope with such a problem, for example, a technique capable of calculating an error included in the detection value of the temperature sensor even after the product is shipped is required.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a new temperature detection device capable of calculating an error included in the detection value.

  In order to solve the above problem, the invention according to claim 1 is provided corresponding to each of a plurality of temperature detection objects (S1 #, S2 #; # = p, n), and detects the temperature of the temperature detection object. Detection values (Vf1, Vf2) of the temperature detection means (T1 #, T2 #) and the temperature detection means (T1 #, T2 #) and the temperature detection means are assumed to have the same temperature. The first calculation means (26) for calculating a value according to the difference (ΔVf) of the first and second values, and the detected value of the temperature detection means based on the value according to the difference calculated by the first calculation means. And second calculating means (14) for calculating an error to be detected.

  When the detection value of the temperature detection means includes an error, the value corresponding to the difference between the detection values in a situation where the temperatures of the plurality of temperature detection targets are the same is different from the initially assumed value. obtain. For this reason, the value according to the difference under the situation where the temperatures of the plurality of temperature detection targets are the same is a parameter for grasping the error included in the detection value. In view of this point, the above invention includes the first calculation unit and the second calculation unit. For this reason, the error contained in the detected value of the temperature detecting means can be calculated with high accuracy. Thereby, for example, the process regarding the temperature of the temperature detection target using the detection value can be appropriately performed.

  Furthermore, according to the above-described invention, for example, unlike the technique described in Patent Document 1, after shipping the temperature detection device, internal parts of the device are replaced or the device is deteriorated over time. Even in this case, the error can be calculated.

1 is a system configuration diagram according to a first embodiment. FIG. The figure which shows the structure regarding the temperature detection of the switching element concerning the embodiment. 6 is a flowchart showing a procedure of power saving processing according to the embodiment. The figure which shows the outline | summary of the error range concerning the embodiment. The flowchart which shows the procedure of the threshold temperature update process concerning the embodiment. The time chart which shows an example of the threshold temperature update process concerning the embodiment. The figure which shows the outline | summary of the abnormality determination process concerning 2nd Embodiment. The top view which shows the circuit board connected to the inverter concerning other embodiment.

(First embodiment)
Hereinafter, a first embodiment in which a temperature detection device according to the present invention is applied to a parallel series hybrid vehicle will be described with reference to the drawings.

  FIG. 1 shows a control system for a motor generator according to the present embodiment.

  The illustrated first motor generator 10a and second motor generator 10b are connected to driving wheels and an engine as an in-vehicle main machine via a power split device (not shown). The first motor generator 10a is connected to the first inverter IV1, and serves as a starter for applying initial rotation to the crankshaft of the engine, a generator for supplying power to the on-vehicle equipment, and the like. On the other hand, the second motor generator 10b is connected to the second inverter IV2, and serves as an in-vehicle main machine. These inverters IV1 and IV2 are connected to the high voltage battery 12 via a converter CV.

  The converter CV includes a capacitor C, a reactor L, and a series connection body of a switching element Scp on the high potential side (upper arm side) and a switching element Scn on the low potential side (lower arm side). Specifically, a series connection body of switching elements Scp and Scn is connected in parallel to the capacitor C, and a connection point of the series connection body and a positive electrode of the high voltage battery 12 are connected via a reactor L. Converter CV has a function of boosting the voltage (for example, “288V”) of high-voltage battery 12 up to a predetermined voltage (for example, “666V”) by opening / closing operation of switching elements Scp, Scn.

  The first inverter IV1 is configured by connecting three series connection bodies of an upper arm side switching element Swp and a lower arm side switching element Swn in parallel. The connection points of these switching elements Swp and switching elements Swn are connected to the U, V, and W phases of the first motor generator 10a, respectively.

  The second inverter IV2 includes three series connection bodies each including a parallel connection body of a pair of switching elements Sp1 and Sp2 on the upper arm side and a parallel connection body of a pair of switching elements Sn1 and Sn2 on the lower arm side. Has been. Specifically, these series connection bodies are connected in parallel to each other, and the connection points of these series connection bodies are respectively connected to the U, V, and W phases of the second motor generator 10b.

  In the present embodiment, the switching element S ¥ # (¥ = 1, 2; # = p, n) constituting the second inverter IV2 is a parallel connection body of a pair of switching elements. This is for increasing the maximum value of the output current of the inverter IV2. This is because the second motor generator 10b is used as an in-vehicle main machine.

  Incidentally, in the present embodiment, the voltage control type is used as the switching elements S * # (* = c, w), S ¥ #, and more specifically, an insulated gate bipolar transistor (IGBT) is used. It is used. Therefore, the switching elements S * # and S ¥ # are opened / closed by the potential difference (gate voltage) of the output terminal (emitter) with respect to the opening / closing control terminal (gate).

  Further, free wheel diodes D * # and D ¥ # are connected in reverse parallel to the switching elements S * # and S ¥ #, respectively. Further, although not shown, a temperature sensitive diode for detecting the temperature of the switching elements S * # and S ¥ # is provided in the vicinity of the switching elements S * # and S ¥ #. The temperature sensitive diode will be described in detail later.

  The control device 14 has a low voltage battery 16 as a power source and is configured mainly with a microcomputer. The control device 14 controls the first motor generator 10a and the second motor generator 10b by operating the converter CV, the first inverter IV1, and the second inverter IV2 via the interface 18.

  Specifically, control device 14 controls the output voltage of converter CV to the command value by opening / closing switching elements Scp and Scn of converter CV. Further, the control device 14 opens and closes the switching elements Swp and Swn of the first inverter IV1, thereby controlling the control amount of the first motor generator 10a to the command value, and the switching element of the second inverter IV2. By opening / closing S1p, S2p, S1n, and S2n, the control amount of the second motor generator 10b is controlled to the command value. In the present embodiment, torque is assumed as the control amount of the first and second motor generators 10a and 10b.

  The upper arm side switching elements S * p, S ¥ p and the corresponding lower arm side switching elements S * n, S ¥ n are alternately turned on. In addition, a torque command value (hereinafter, torque command value Trq *) as a control amount is input to the control device 14 from, for example, a host control device that controls the vehicle.

  The interface 18 is a transmission means for exchanging signals between the high voltage system including the high voltage battery 12 and the low voltage system including the low voltage battery 16 while electrically insulating the interface. . In this embodiment, the interface 18 is provided with an optical insulating element (photocoupler). In the present embodiment, the high voltage system corresponds to the first region, and the low voltage system corresponds to the second region.

  Next, a configuration for detecting the temperature of the switching element provided in each of the converter CV, the first inverter IV1, and the second inverter IV2 will be described. In the present embodiment, as shown in FIG. 2, the second inverter IV2 will be described as an example. In FIG. 2, description of components for opening / closing the switching elements S1 # and S2 # is omitted. In the present embodiment, hereinafter, the switching element S1 # is referred to as a first switching element, and the switching element S2 # is referred to as a second switching element.

  As shown in the figure, in the high voltage system, a first temperature sensing diode T1 # for detecting the temperature of this element is provided near the first switching element S1 #. On the other hand, in the vicinity of the second switching element S2 #, a second temperature sensitive diode T2 # for detecting the temperature of this element is provided. In this embodiment, the temperature sensitive diodes having the same specifications are used as the temperature sensitive diodes T # 1 and T # 2.

  Incidentally, the switching element S ¥ # (¥ = 1, 2; # = p, n), the free wheel diode D ¥ # and the temperature sensitive diode T ¥ # are actually packaged by being housed in the power card PWC. It has become.

  The high voltage system includes a drive IC 20. The drive IC 20 is a one-chip semiconductor integrated circuit, and includes a first constant voltage power supply 22a, a second constant voltage power supply 22b, a first constant current power supply 24a, a second constant current power supply 24b, and a differential amplification. A circuit 26 and a comparator 28 are provided. The drive IC 20 is provided corresponding to each of the six pairs of switching elements S1 # and S2 # provided in the second inverter IV2.

  The first constant voltage power supply 22a has a terminal voltage of “VH” and serves as a power supply source for the first constant voltage power supply 22a. The output side of the first constant current power supply 24a is connected to the anode of the first temperature sensitive diode T1 # via the terminal T1 of the drive IC 20. The cathode of the first temperature sensitive diode T1 # is grounded.

  On the other hand, the second constant voltage power supply 22b has the same terminal voltage as the terminal voltage of the first constant voltage power supply 22a, and serves as a power supply source for the second constant current power supply 24b. The output current of the second constant current power supply 24b is the same as the output current of the first constant current power supply 24a. The output side of the second constant current power supply 24b is connected to the anode of the second temperature sensitive diode T2 # via the terminal T2 of the drive IC 20, and the cathode is grounded.

  According to such a configuration, the first temperature sensing diode T1 # serves as a temperature detection unit that detects the temperature of the first switching element S1 # as a voltage drop amount in itself (hereinafter referred to as a first voltage drop amount Vf1). . The second temperature sensing diode T2 # serves as a temperature detection unit that detects the temperature of the second switching element S2 # as a voltage drop amount in itself (hereinafter, a second voltage drop amount Vf2). Specifically, the first voltage drop amount Vf1 has a negative correlation with the temperature of the first switching element S1 #, and the second voltage drop amount Vf2 is negative with the temperature of the second switching element S2 #. Has a correlation.

  The terminals T1 and T2 are connected to the differential amplifier circuit 26. Specifically, the terminal T1 is connected to the non-inverting input terminal side of the differential amplifier circuit 26, and the terminal T2 is connected to the inverting input terminal side of the differential amplifier circuit 26. A constant voltage power source 27 for shifting the output voltage of the differential amplifier circuit 26 is connected to the non-inverting input terminal of the differential amplifier circuit 26.

  The output terminal of the differential amplifier circuit 26 and the terminal T1 can be connected to the non-inverting input terminal of the comparator 28 via the switch 30. The switch 30 is a member for selectively connecting either the output terminal of the differential amplifier circuit 26 or the terminal T1 and the non-inverting input terminal of the comparator 28. In the present embodiment, the switch 30 is basically operated to connect the terminal T1 and the non-inverting input terminal of the comparator 28.

  A carrier generation circuit 34 that outputs a carrier signal (triangular wave signal) is connected to the inverting input terminal of the comparator 28.

  The output terminal of the comparator 28 is grounded via the terminal T3 of the drive IC 20 and the primary side (photodiode 36a) of the photocoupler 36 constituting the interface 18. A constant voltage power supply 40 is connected to a connection point between the terminal T3 and the photodiode 36a through a resistor 38.

  On the other hand, the collector on the secondary side (phototransistor 36b) of the photocoupler 36 is connected to a constant voltage power supply 44 via a resistor 42, and the emitter of the phototransistor 36b is grounded. The connection point between the resistor 42 and the constant voltage power supply 44 is grounded via a capacitor 46.

  The collector side of the phototransistor 36b among both ends of the resistor 42 is connected to the control device 14 via a low-pass filter 48 including a resistor and a capacitor.

  According to such a configuration, the pulse width modulated input signal at the non-inverting input terminal of the comparator 28 is input to the control device 14.

  The terminals T1 and T2 are further connected to the drive control unit 50. The drive control unit 50 operates the switch 30 or performs a local shutdown process. In the local shutdown process, the condition that the first voltage drop amount Vf1 is lower than the specified voltage (the temperature of the first switching element S1 # is higher than the specified temperature), and the second voltage drop amount Vf2 is lower than the specified voltage. When it is determined that the logical sum of the condition (the temperature of the second switching element S2 # exceeds the specified temperature) is true, the first and second switching elements S1 are determined to be in an overheated state. This is a process for prohibiting the driving of #, S2 #. Here, the specified temperature is a lower limit value of the temperature of the switching element at which the reliability of the switching element greatly decreases in a short time, and the specified voltage is a value in the temperature sensitive diode when the temperature of the switching element becomes the specified temperature. The voltage drop is set. According to the local shutdown process, the switching element can be quickly turned off, and a situation in which the reliability of the switching element is greatly reduced due to overheating of the switching element can be avoided.

  Information about the first voltage drop amount Vf 1 and the output signal of the differential amplifier circuit 26 is transmitted to the control device 14 via the interface 18. The control device 14 performs a temperature calculation process for calculating the temperature of the first switching element S1 # by software processing based on information on the first voltage drop amount Vf1. In the present embodiment, as the information related to the first voltage drop amount Vf1, a time ratio signal output from the comparator 28 by the magnitude comparison between the triangular wave signal output from the carrier generation circuit 34 and the first voltage drop amount Vf1 is adopted. doing. This time ratio signal has a correlation with the temperature of the first switching element S1 #.

  Note that the interface 18 connected to the differential amplifier circuit 26, the comparator 28, the switch 30, the carrier generation circuit 34, and the terminal T3 is actually the six pairs of switching elements S1 # and S2 provided in the second inverter IV2. Only one of the drive ICs 20 corresponding to # is provided. Specifically, it is provided only in the drive IC 20 corresponding to the six pairs of switching elements S1 # and S2 # that are assumed to have the highest temperature. Thereby, the number of components can be reduced as compared with the configuration in which the drive IC 20 corresponding to each of the six pairs of switching elements S1 # and S2 # is provided with the differential amplifier circuit 26, the interface 18, and the like. A method of using the differential amplifier circuit 26 and the switch 30 will be described later.

  The configuration of the drive IC 20 and the like corresponding to the switching element Sw # (# = p, n) provided in the first inverter IV1 will be described. The drive IC 20 corresponding to each of the six switching elements Sw # is provided. Yes. Here, in the present embodiment, the differential amplifier circuit 26 and the switch 30 are not provided in the drive IC 20 of the first inverter IV1. Further, the interface 18 connected to the comparator 28, the carrier generation circuit 34, and the terminal T3 is actually the drive IC 20 that is assumed to have the highest temperature among the drive ICs 20 corresponding to each of the six switching elements Sw #. It is provided for only. Incidentally, the configuration of the drive IC 20 and the like corresponding to each of the six switching elements Sc # provided in the converter CV is the same as the configuration of the drive IC 20 and the like of the first inverter IV1.

  Next, the power saving process executed by the control device 14 will be described.

  In this process, for each of the converter CV, the first inverter IV1 and the second inverter IV2, it is determined that the temperature Tsw of the switching element calculated by the temperature calculation process has exceeded the threshold temperature Toc lower than the specified temperature. In this case, the torque command value Trq * is limited, and the process relates to the heating protection of the switching element. According to this process, it is possible to limit the collector current by limiting the driving of the switching element, and to avoid overheating of the switching element.

  FIG. 3 shows the procedure of the power saving process. This process is repeatedly executed by the control device 14 at a predetermined cycle, for example.

  In this series of processes, first, in step S10, it is determined whether or not a flag F indicating whether or not the torque command value Trq * is limited is “1”. Here, the flag F indicates that the torque command value Trq * is limited by “1”, and indicates that it is not limited by “0”.

  If a negative determination is made in step S10, the process proceeds to step S12, and it is determined whether or not the temperature Tsw of the switching element has exceeded the threshold temperature Toc. This process is a process for determining whether to start limiting the torque command value Trq *. Note that the threshold temperature Toc is set based on the allowable upper limit value of the actual temperature of this element that can drive the switching element without limiting the driving of the switching element by the power saving process.

  If an affirmative determination is made in step S12, the process proceeds to step S14 where the flag F is set to “1” and the torque guard value MAXTrq for performing the guard process on the torque command value Trq * is set to the first limit value Trqth1. . Here, the first limit value Trqth1 is set to a value smaller than the second limit value Trqth2, which is the torque guard value MAXTrq during normal control of the converter CV, the first inverter IV1, and the second inverter IV2. ing.

  If an affirmative determination is made in step S10, it is determined that the torque command value Trq * is limited, and the process proceeds to step S16. In step S16, it is determined whether or not the temperature Tsw of the switching element has become equal to or lower than the threshold temperature Toc. This process is for determining whether or not a condition for canceling the limit of the torque command value Trq * is satisfied.

  If an affirmative determination is made in step S16, the process proceeds to step S18, where the flag F is initialized and the torque guard value MAXTrq is changed to the second limit value Trqth2. Thereby, the restriction | limiting of torque command value Trq * is cancelled | released.

  If a negative determination is made in steps S12 and S16, or if the processes in steps S14 and S18 are completed, the series of processes is temporarily terminated.

  Next, the threshold temperature update process executed by the control device 14 will be described.

  This process is a process for updating the threshold temperature Toc in the power saving process for the second inverter IV2, and is performed in view of the fact that an error may be included in the voltage drop amount in the temperature sensitive diode. Here, the error included in the voltage drop amount is a difference between the actual value and the central characteristic value with respect to the voltage drop amount in the temperature sensitive diode when the actual temperature of the switching element becomes a predetermined temperature. The central characteristic value is an average value of voltage drop amounts in a plurality of mass-produced temperature sensitive diodes when the actual temperature of the switching element is a predetermined temperature. The above error is caused by individual differences of temperature sensitive diodes. Hereinafter, the threshold temperature update process will be described in detail.

  First, in describing the above processing, a range that the error can take (hereinafter, an error range) will be described.

  In the second inverter IV2, the first voltage drop amount Vf1 and the second voltage drop amount Vf2 are expressed by the following expressions (c1) and (c2).

Vf1 = V1r + ΔV1 (c1)
Vf2 = V2r + ΔV2 (c2)
In the above equation, “V1r” represents a central characteristic value of the first voltage drop amount Vf1, and “ΔV1” represents an error included in the first voltage drop amount Vf1 (hereinafter referred to as a first error). “V2r” indicates a central characteristic value of the second voltage drop amount Vf2, and “ΔV2” indicates an error included in the second voltage drop amount Vf2 (hereinafter referred to as a second error).

  Difference information ΔVf, which is a value obtained by subtracting the second voltage drop amount Vf2 from the first voltage drop amount Vf1, is shown in the following equation (c3).

ΔVf = Vf1−Vf2
= (V1r-V2r) + (ΔV1-ΔV2) (c3)
Here, if the temperature of the first switching element S1 # and the temperature of the second switching element S2 # are the same, “V1r = V2r” is established. In this case, the difference information ΔVf is expressed by the following equation (c4).

ΔVf = ΔV1−ΔV2 (c4)
When the first error ΔV1 and the second error ΔV2 are “0”, the difference information ΔVf expressed by the above equation (c4) is “0”. On the other hand, when the first error ΔV1 and the second error ΔV2 are values other than “0”, the difference information ΔVf may deviate from the initially assumed value “0”.

  Here, in this embodiment, the initial error ranges of the first error ΔV1 and the second error ΔV2 are the same, and these error ranges are expressed by the following equation (c5).

−a ≦ ΔV1 ≦ a, −a ≦ ΔV2 ≦ a (a> 0) (c5)
The error range is a fixed range that is determined according to the specification of the temperature sensitive diode, and is a range that is guaranteed during the lifetime of the temperature sensitive diode. The first error ΔV1 and the second error ΔV2 are guaranteed by the above equation (c5) and the relationship of the above equation (c4), and the first error ΔV1 and the second error ΔV2 are guaranteed. The error range of each of the two errors ΔV2 can be updated. Specifically, as shown in FIG. 4, when the difference information ΔVf is a negative value, each error range of the first error ΔV1 and the second error ΔV2 can be expressed by the following equation (c6). .

−a ≦ ΔV1 ≦ a− | ΔVf |, −a + | ΔVf | ≦ ΔV2 ≦ a (c6)
On the other hand, when the difference information ΔVf is a positive value, the error ranges of the first error ΔV1 and the second error ΔV2 can be expressed by the following equation (c7).

−a + | ΔVf | ≦ ΔV1 ≦ a, −a ≦ ΔV2 ≦ a− | ΔVf | (c7)
Next, a method for updating the threshold temperature Toc based on the error will be described.

  In the present embodiment, when the error calculated based on the difference information ΔVf is to reduce the positive boundary value “a” in the initial error range “−a ≦ ΔV1 ≦ a”, the difference information ΔVf Based on this, the threshold temperature Toc is updated. As a result, the power saving process is changed.

  Specifically, the error range of the first error ΔV1 expressed by the above equation (c6) is the positive boundary value in the initial error range “−a ≦ ΔV1 ≦ a” from “a” to “a− | ΔVf | ”is reduced. Here, the threshold temperature Toc used in the power saving process is actually the boundary value on the positive side of the initial error range from the viewpoint of maintaining the reliability of the first switching element S1 #. When the first temperature-sensitive diode T1 # having the characteristic “a” is used, the switching calculated by the temperature calculation process when the actual temperature of the first switching element S1 # becomes the allowable upper limit value. The temperature Tsw of the element is set. Since the first voltage drop amount Vf1 and the temperature of the first switching element S1 # have a negative correlation as described above, the temperature detection is performed when the boundary value on the positive side is reduced by the absolute value of the difference information ΔVf. Since the error is reduced, the threshold temperature Toc is updated to the higher side by the temperature information ΔTf that is the temperature corresponding to the difference information ΔVf. As a result, the frequency with which the torque command value Trq * is limited by the power saving process can be reduced.

  FIG. 5 shows the procedure of the threshold temperature update process. This process is executed by the control device 14.

  In this series of processes, first, in step S20, it is determined whether or not the input of the torque command value Trq * is started. This process is a process for determining whether or not the temperatures of the first switching element S1 # and the second switching element S2 # are the same. That is, before the torque command value Trq * is input, since the driving of the switching element has not yet started, there is a probability that the temperatures of the first switching element S1 # and the second switching element S2 # are the same. Is expensive. By calculating the difference information ΔVf in such a situation, the update accuracy of the threshold temperature Toc can be increased.

  In addition, when it is determined that the elapsed time from the last stop of the second inverter IV2 to the present time is equal to or less than the specified time, it is desirable not to perform the threshold temperature update process. This is because when the elapsed time is short, the first switching element S1 # and the second switching element S2 # are not in thermal equilibrium, and the switching elements S1 # and S2 # This is because the probability that the temperatures are not the same is high.

  If a negative determination is made in step S20, the switch 30 is operated so as to connect the non-inverting input terminal of the comparator 28 and the output terminal of the differential amplifier circuit 26, and the process proceeds to step S22. In step S22, the temperature information ΔTf is calculated based on the output signal of the comparator 28 (information regarding the difference information ΔVf) transmitted through the interface 18. Incidentally, in the present embodiment, the difference information ΔVf is converted into a time ratio signal having a correlation with the difference information ΔVf in the comparator 28. Here, in the present embodiment, the terminal voltage of the constant voltage power supply 27 is set so that the time ratio of the time ratio signal is “50%” when the difference information ΔVf is “0”. For this reason, according to the said time ratio signal, the control apparatus 14 can grasp | ascertain the code | symbol with the absolute value of difference information (DELTA) Vf.

  In subsequent step S24, the threshold temperature Toc is updated based on the temperature information ΔTf.

  If an affirmative determination is made in step S20 or if the process in step S24 is completed, the series of processes is temporarily terminated.

  FIG. 6 shows an example of the threshold temperature update process. Specifically, FIG. 6A shows the transition of whether or not power is supplied from the low-voltage battery 16 to the in-vehicle device, and FIG. 6B relates to the difference information ΔVf input to the control device 14 via the interface 18. FIG. 6C shows the transition of the information, FIG. 6C shows the transition of the driving signal input to the gate of the switching element, and FIG. 6D shows the first transition input to the control device 14 via the interface 18. The transition of information about the voltage drop amount Vf1 is shown.

  In the illustrated example, at time t1, for example, when the ignition switch is turned on by the user of the vehicle, the vehicle control system is activated, and power supply from the low-voltage battery 16 to the various in-vehicle devices is started. Then, at a predetermined timing before time t2 when the torque command value Trq * is input to the control device 14, information regarding the difference information ΔVf is input to the control device 14 and threshold temperature update processing is performed.

  Then, at time t2, a drive signal is output from the control device 14 to the gate of the switching element, so that the driving of the switching element is started. Accordingly, information regarding the first voltage drop amount Vf <b> 1 starts to be input to the control device 14 via the interface 18.

  According to the embodiment described in detail above, the following effects can be obtained.

  (1) The threshold temperature update process is performed every time the vehicle control system is activated. For this reason, for example, even when the circuit board on which the drive IC 20 is mounted is replaced at a vehicle repair shop, or the error included in the voltage drop amount changes due to aging of the temperature sensitive diode or the like, these Can effectively suppress the effect of the power saving process.

  (2) The differential amplifier circuit 26 provided in the high voltage system calculates the difference information ΔVf and transmits the difference information ΔVf to the control device 14 provided in the low voltage system via the interface 18. In the configuration in which information is transmitted from the high voltage system to the low voltage system, information input to the control device 14 due to the presence of the interface 18 (the photocoupler 36 or the low pass filter 48) in the information transmission path, or the like. It may vary from the original information output from the high voltage system. Here, for example, a configuration in which each of the first voltage drop amount Vf1 and the second voltage drop amount Vf2 is transmitted from the high voltage system to the control device 14 and the control device 14 calculates the difference information ΔVf may be adopted. Conceivable. However, in this case, there is a concern that the calculation accuracy of the difference information ΔVf may be reduced due to the fact that the information regarding both the first voltage drop amount Vf1 and the second voltage drop amount Vf2 changes from the original information.

  On the other hand, according to the configuration according to the present embodiment, the information related to the difference information ΔVf input to the control device 14 is less affected by the transmission path. For this reason, the update accuracy of the threshold temperature Toc based on the temperature information ΔTf corresponding to the difference information ΔVf can be increased.

  (3) Each of the first switching element S1 # and the second switching element S2 # connected to each other provided in the second inverter IV2 is set as a temperature detection target for calculating the difference information ΔVf. These switching elements S1 # and S2 # are driven by a common drive IC 20 to perform the same switching operation. For this reason, the thermal histories applied to the switching elements S1 # and S2 # are substantially the same, and accordingly, the progress of the aging deterioration of the switching elements S1 # and S2 # is considered to be substantially the same. Therefore, by setting the temperature detection target to the first switching element S1 # and the second switching element S2 #, it is possible to improve the calculation accuracy of the first error ΔV1 based on the difference information ΔVf, and consequently the threshold temperature Toc. Update accuracy can be improved.

(Second Embodiment)
Hereinafter, the second embodiment will be described with reference to the drawings with a focus on differences from the first embodiment.

  In this embodiment, immediately before the threshold temperature update process is performed, the control device 14 determines whether there is an abnormality related to temperature detection by the first temperature sensing diode T1 # or the second temperature sensing diode T2 #. I do. Here, the abnormality relating to the temperature detection includes, for example, the first temperature sensing diode T1 #, the second temperature sensing diode T2 #, the terminal T1, the terminal T2, and the terminal T1 to the first temperature sensing diode T1 #. An open fault is included in the electrical path and the electrical path from the terminal T2 to the second temperature sensitive diode T2 #. Hereinafter, with reference to FIG. 7, the principle by which the abnormality can be detected by this process will be described. In addition, the vertical axis | shaft of FIG. 7 has shown the absolute value of difference information (DELTA) Vf.

  When the abnormality related to the temperature detection does not occur, the absolute value of the difference information ΔVf is within a specified range defined by the minimum value Vmin and the maximum value Vmax.

  On the other hand, when an abnormality relating to the temperature detection occurs, any one of the pair of input terminals of the differential amplifier circuit 26 is applied to the terminals of the first constant voltage power supply 22a or the second constant voltage power supply 22b. The voltage will rise to VH. In this case, the absolute value of the difference information ΔVf exceeds the maximum value Vmax.

  In view of these points, if it is determined that the absolute value of the difference information ΔVf exceeds the maximum value Vmax based on the output signal of the comparator 28 transmitted via the interface 18, an abnormality relating to the temperature detection has occurred. to decide. In this embodiment, when it is determined that an abnormality relating to the temperature detection has occurred, the threshold temperature update process is not performed, and a process for notifying the user that the abnormality has occurred is performed.

  Thus, according to the abnormality determination process, an abnormality relating to temperature detection by the first temperature sensing diode T1 # or the second temperature sensing diode T2 # can be detected. For this reason, it can be avoided that the threshold temperature Toc updated based on the difference information ΔVf with low reliability is used in the power saving process.

(Other embodiments)
Each of the above embodiments may be modified as follows.

  The temperature detecting means is not limited to the temperature sensitive diode, and may be, for example, a resistance temperature detector.

  In the first embodiment, the temperature sensitive diode in which the absolute values of the positive boundary value and the negative boundary value are the same “a” in the error range is adopted, but the present invention is not limited to this. You may employ | adopt the temperature sensitive diode from which absolute values differ.

  In the first embodiment, the differential amplifier circuit 26 and the comparator 28 correspond to only one pair among the six pairs of switching elements S1 #, S2 # (# = p, n) provided in the second inverter IV2. Although the configuration including the carrier generation circuit 34 and the interface 18 is employed, the configuration is not limited thereto. For example, a configuration including the differential amplifier circuit 26 and the like corresponding to each of the six pairs of switching elements S1 # and S2 # may be employed.

  The plurality of temperature detection targets are not limited to the pair of switching elements S1 # and S2 # connected in parallel to each other. For example, three or more switching elements connected in parallel to each other may be used. Here, a plurality of temperature detection targets are assumed to be three switching elements connected in parallel to each other, and the temperature sensing diodes for detecting the respective temperatures of these switching elements are the first temperature sensing diode, the second temperature sensing diode, and the first temperature sensing diode. A method for reducing the boundary value on the positive side of the error range when referred to as the temperature sensitive diode 3 will be described.

  Specifically, first, the first difference information that is the difference between the first voltage drop amount Vf1 and the second voltage drop amount Vf2, and the voltage drop amount in the third temperature sensing diode (third voltage drop amount Vf3). And second difference information which is a difference between the second voltage drop amount Vf2. The first difference information and the second difference are based on the assumption that each error range of the first to third voltage drop amounts Vf1 to Vf3 is guaranteed by a predetermined range (for example, the above equation (c5)). Based on the information, at least one error range among the first to third voltage drop amounts Vf1 to Vf3 can be reduced.

  Further, the plurality of temperature detection targets are not limited to the pair of switching elements S1 # and S2 # provided in the second inverter IV2. For example, as shown in FIG. 8, at least two or more of the lower arm side switching elements Swn provided in the first inverter IV1 and the lower arm side switching elements Sn1 and Sn2 provided in the second inverter IV2 may be used. Good. Here, FIG. 8 is a plan view of a circuit board on which a power card accommodating the switching elements of the first inverter IV1 and the second inverter IV2 is mounted. Note that a lower arm side switching element provided in the converter CV may be included in a plurality of temperature detection target candidate lower arm side switching elements.

  Incidentally, in FIG. 8, a plurality of temperature detection targets are not included including the switching elements on the upper arm side and the switching elements on the lower arm side. This is because, as shown in FIG. 8, the switching elements on the upper arm side are insulated from each other and the switching elements on the upper arm side are electrically insulated from the switching elements on the lower arm side. This is because the circuit board is provided with the insulating region IA. Note that the switching elements S1 # and S2 # of the second inverter IV2 are not insulated from each other. This is because the emitters of the pair of switching elements S1 # and S2 # are short-circuited, and the emitter potentials of the pair of switching elements S1 # and S2 # are the same.

  Furthermore, the plurality of temperature detection targets are not limited to those described above. When the switching element provided in the converter CV and the first inverter IV1 is a parallel connection body of a pair of switching elements, the pair of switching elements provided in the converter CV and the first inverter IV1 may be a plurality of temperature detection targets. . In this case, the information regarding the error contained in the voltage drop amount in the temperature sensing diode provided in the converter CV, the first inverter IV1, and the second inverter IV2 can be collected in the control device 14. Thereby, it is possible to update the threshold temperature Toc with reference to information about other errors, or to unify the execution subject of processing based on the information about errors into the control device 14.

  The first region and the second region are not limited to those exemplified in the first embodiment. For example, if it is necessary to transmit some temperature detection value in the low voltage system from the low voltage system to the high voltage system, the low voltage system may be the first region and the high voltage system may be the second region.

  In the first embodiment, the first temperature sensing diode T1 # and the second temperature sensing diode T2 # have the same specifications (the voltage drop amount is basically the same when the same constant current is supplied). Is the same), but is not limited to this. For example, the voltage drop amount may be different because the number of temperature-sensitive diodes connected in series is different. Even in this case, if the voltage drop amount in the temperature sensitive diode includes an error, the difference between the voltage drop amounts in the pair of temperature sensitive diodes deviates from the initially assumed value. For this reason, an error can be calculated based on the difference information.

  The first calculation means includes not only the differential amplifier circuit 26 that calculates a value (difference information ΔVf) according to the difference between the voltage drop amounts in the pair of temperature sensitive diodes, but also the difference between the voltage drop amounts. A direct calculation circuit is also included.

  In the first embodiment, a configuration is adopted in which the differential amplifier circuit 26 as the first calculation unit and the control device 14 as the second calculation unit are provided in different regions. . For example, a configuration in which both the first calculation unit and the second calculation unit are provided in the high voltage system may be employed. In this case, the abnormality determination process described in the second embodiment may be performed in the high voltage system. Specifically, for example, the drive IC 20 is provided with a comparator to which a signal indicating the absolute value of the difference information ΔVf and a signal indicating the maximum value Vmax are input, and abnormality determination processing is performed based on the logical value of the output signal of the comparator. Just do it. Here, the abnormality determination process may be performed at a timing near the execution timing of the threshold temperature update process.

  In the first embodiment, the difference information ΔVf is calculated in the high voltage system, and the difference information ΔVf is transmitted to the control device 14 via the interface 18. However, the present invention is not limited to this. For example, a configuration in which the first voltage drop amount Vf1 and the second voltage drop amount Vf2 are transmitted to the control device 14 via the interface 18 and the difference information ΔVf is calculated in the control device 14 may be employed.

  -The parameter to be restricted by the power saving process is not limited to the torque command value Trq *. For example, current may be used. For example, a known current feedback control is performed in which the command currents id * and iq * are set based on the torque command value Trq * and the actual currents id and iq are feedback-controlled to the command currents id * and iq *. And it can carry out by performing guard processing to command current id * and iq *.

  -Processing related to temperature protection is not limited to processing related to overheating protection of switching elements such as power saving processing. For example, when it is determined that the temperature Tsw of the switching element is lower than the second threshold temperature sufficiently lower than the threshold temperature Toc, a process for protecting the switching element from a low temperature state (for example, a process for heating the switching element) is performed. If there is a problem, this processing may be performed. In this case, as a changing means for changing the process for protecting from the low temperature state, the error calculated based on the difference information ΔVf is changed from the negative boundary value within the initial error range from “−a” to “−a + | ΔVf | In this case, the second threshold temperature may be updated to the lower side by the temperature information ΔTf corresponding to the difference information ΔVf.

  In step S16 of FIG. 3 in the first embodiment, the threshold for canceling the restriction of the torque command value Trq * may be set to a temperature slightly lower than the threshold temperature Toc instead of the threshold temperature Toc. Good. As a result, hysteresis can be provided between the start and release of the limit of the torque command value Trq *, and the start and stop of the power saving process due to the temperature Tsw of the switching element fluctuating in the vicinity of the threshold temperature Toc. The situation where the release is repeated frequently can be avoided.

  The switching element that is a temperature detection target is not limited to the IGBT but may be a MOSFET, for example. Further, the temperature detection target is not limited to a switching element, and is not limited to that provided in a power conversion circuit such as a converter or an inverter.

  The interface 18 is not limited to the one provided with the optical insulating element, and may be provided with a magnetic insulating element (for example, a pulse transformer), for example.

  DESCRIPTION OF SYMBOLS 14 ... Control apparatus, 26 ... Differential amplifier circuit, S1 # (# = p, n) ... 1st switching element, S2 # ... 2nd switching element, T1 # ... 1st temperature sensitive diode, T2 # ... Second temperature sensitive diode.

Claims (6)

Temperature detection means (T1 #, T2 #) provided corresponding to each of the plurality of temperature detection targets (S1 #, S2 #; # = p, n) and detecting the temperature of the temperature detection target;
In a situation where the temperatures of the plurality of temperature detection targets are assumed to be the same, a value corresponding to the difference (ΔVf) between the detection values (Vf1, Vf2) of the plurality of temperature detection means is calculated. 1 calculating means (26);
Second calculation means (14) for calculating an error included in the detection value of the temperature detection means based on a value corresponding to the difference calculated by the first calculation means;
A temperature detecting device comprising: The first calculation means is provided in a first region where the temperature detection target and the temperature detection means are provided,
The second calculation means is provided in a second area different from the first area,
The temperature detection apparatus according to claim 1, further comprising a transmission means (18) for transmitting a value corresponding to the difference calculated by the first calculation means to the second calculation means. Applied to a power conversion circuit (IV2) including a series connection body of a switching element (S ¥ p; ¥ = 1, 2) on the high potential side and a switching element (S ¥ n) on the low potential side,
The switching element is opened / closed by a potential difference of the output terminal with respect to the opening / closing control terminal,
The plurality of temperature detection targets are at least two of the switching elements provided in the power conversion circuit, the potentials of the output terminals being the same.
The temperature detection apparatus according to claim 1, further comprising a changing unit that changes a process related to temperature protection of the temperature detection target based on the error calculated by the second calculation unit. The switching elements are a plurality of switching elements (S1 #, S2 #) connected in parallel to each other,
The temperature detection apparatus according to claim 3, wherein the plurality of temperature detection targets are the plurality of switching elements.   5. The temperature detection device according to claim 3, wherein the situation assumed to be the same is a situation before driving of the switching element is started.   An abnormality determination for determining that an abnormality relating to temperature detection by the temperature detection means has occurred based on an absolute value of a value corresponding to the difference calculated by the first calculation means exceeding a specified value (Vmax). The temperature detection apparatus according to claim 1, further comprising means.

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