Abnormality detection method for inverter and abnormality detection system for inverter

Abstract

To provide an abnormality detection method for an inverter capable of detecting abnormality of the inverter without increasing an operation load.SOLUTION: There is provided an abnormality detection method for an inverter converting direct-current power from a power supply to alternating-current power and supplying the alternating-current power to a motor. The inverter comprises a plurality of switching elements. The abnormality detection method includes: on the basis of requested torque of the motor, calculating a current command value for controlling operation of the plurality of switching elements; detecting a temperature of each switching element and a temperature of cooling water for cooling the inverter; and estimating a temperature of the switching element on the basis of the current command value and the temperature of the cooling water; and determining that the inverter is abnormal when a difference between the estimated temperature and a detected temperature of each switching element is equal to or larger than a predetermined value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an inverter abnormality detection method and an inverter abnormality detection system. [Background technology]

[0002] Patent Document 1 discloses a method for determining whether an inverter comprising a plurality of switching elements has an abnormality. In this abnormality determination method, current is supplied from the inverter to a motor, and while the motor is being driven, the current of each phase of the motor and the magnetic pole position (angle) of the rotor are detected. Then, based on the detected current and the magnetic pole position of the rotor, the current integrated value for the positive section and the current integrated value for the negative section of each phase current are calculated, and the integrated values are compared, and based on the comparison result, it is determined whether or not there is an abnormality in the inverter. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-215328 Summary of the Invention [Problem to be solved by the invention]

[0004] In the abnormality detection method described in Patent Document 1, while the motor is being driven, the current of each phase of the motor and the magnetic pole position (angle) of the rotor are detected and an integrated current value is calculated. However, when the motor is rotating at high speed, the frequency of the current and angle becomes high. For this reason, it is necessary to process the detection of the magnetic pole position and the calculation of the integrated current value at high speed (shorten the calculation cycle). However, shortening the calculation cycle increases the calculation load on the controller.

[0005] The present invention has been made in view of the above-mentioned problems, and has an object to provide an inverter abnormality detection method that can detect an inverter abnormality without increasing the calculation load. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a method for detecting an abnormality in an inverter that converts DC power from a power source into AC power and supplies it to a motor. The inverter includes a plurality of switching elements. The method calculates a current command value for controlling the operation of the plurality of switching elements based on a torque required by the motor, detects the temperature of each switching element and the temperature of cooling water that cools the inverter, and estimates the temperature of the switching elements based on the current command value and the temperature of the cooling water. If a difference between the estimated temperature of the switching element and the detected temperature of each switching element is equal to or greater than a predetermined value, the method determines that the inverter is abnormal. [Effects of the Invention]

[0007] According to the present invention, an abnormality in the inverter is detected from the difference between the estimated temperature of the switching elements, which is estimated based on the current command value and the coolant temperature, and the detected temperature of each switching element. Therefore, an abnormality in the inverter can be detected without increasing the calculation load even when the motor is rotating at high speed. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram of an inverter abnormality detection system common to all embodiments. [Figure 2] FIG. 2 is a block diagram showing the configuration of the inverter abnormality detection calculation process in the motor controller. [Figure 3] FIG. 3 is a flowchart illustrating the inverter abnormality detection control according to the first embodiment. [Figure 4] FIG. 4 is a flowchart illustrating the inverter abnormality diagnosis process. [Figure 5] FIG. 5 is a block diagram showing the configuration of a motor controller in the second embodiment. [Figure 6] FIG. 6 is a diagram illustrating the effect of performing delay correction on the estimated temperature. [Figure 7]FIG. 7 is a flowchart illustrating inverter abnormality detection control according to the second embodiment. [Figure 8] FIG. 8 is a block diagram showing the configuration of a motor controller in the third embodiment. [Figure 9] FIG. 9 is a diagram illustrating the effect of performing leading correction on the detected temperature. [Figure 10] FIG. 10 is a flowchart illustrating inverter abnormality detection control according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] [First embodiment] 1 is a schematic diagram of an inverter abnormality detection system (hereinafter also referred to as an abnormality detection system) 100 that employs the inverter abnormality detection method of the present invention. The abnormality detection system 100 is basically intended to be mounted on an electric vehicle, but is not necessarily limited to this. Furthermore, the electric vehicle referred to here includes not only electric vehicles but also hybrid vehicles, fuel cell vehicles, etc.

[0011] 1, the abnormality detection system 100 includes a battery 1, a relay 2, an inverter 3, a motor 4, a capacitor 5, a current sensor 6, a magnetic pole position detection sensor 7, a cooling device 8, a controller 9, and a gate drive circuit 10. The controller 9 includes a vehicle controller 91 and a motor controller 92.

[0012] The battery 1, the relay 2, the inverter 3, and the capacitor 5 constitute a power supply device, and power is supplied from the battery 1 to the motor 4 via the relay 2 and the inverter 3.

[0013] The battery (power supply) 1 is a secondary battery, and is connected to an inverter 3 via a relay 2. The battery 1 outputs DC power.

[0014] The relay 2 is a switching means that controls the driving or stopping of the power supply device. The relay 2 is driven to open and close by the vehicle controller 91 in conjunction with the on / off operation of the vehicle key switch.

[0015] The inverter 3 converts DC power from the battery 1 into AC power and supplies it to the motor 4. The inverter 3 includes multiple switching elements (insulated gate bipolar transistors (IGBTs)) Tr1-Tr6 and rectifying elements (diodes) D1-D6. The switching elements Tr1-Tr6 and the rectifying elements D1-D6 form switching circuits UP, UN, VP, VN, WP, and WN, respectively. The rectifying elements D1-D6 are connected in parallel with the switching elements Tr1-Tr6, respectively. The rectifying elements D1-D6 are arranged so that current flows in the opposite direction to the rectifying direction of the switching elements Tr1-Tr6. The switching elements are connected in series, two by two, and one of the three-phase (UVW) inputs of the motor 4 is connected between any two of the series-connected switching elements. As a result, the switching elements Tr1-Tr6 and the rectifying elements D1-D6 form a pair of upper and lower arms for each phase of the motor 4.

[0016] Specifically, switching elements Tr1 and Tr2, switching elements Tr3 and Tr4, and switching elements Tr5 and Tr6 are connected in series. The connection point of switching elements Tr1 and Tr2 is connected to the U-phase input of motor 4, with switching element Tr1 and rectifier element D1 (i.e., switching circuit UP) forming a U-phase upper arm and switching element Tr2 and rectifier element D2 (i.e., switching circuit UN) forming a U-phase lower arm. The connection point of switching elements Tr3 and Tr4 is connected to the V-phase input of motor 4, with switching element Tr3 and rectifier element D3 (i.e., switching circuit VP) forming a V-phase upper arm and switching element Tr4 and rectifier element D4 (i.e., switching circuit VN) forming a V-phase lower arm. Similarly, the connection point of switching elements Tr5 and Tr6 is connected to the W-phase input of the motor 4, with switching element Tr5 and rectifier element D5 (i.e., switching circuit WP) forming the W-phase upper arm and switching element Tr6 and rectifier element D6 (i.e., switching circuit WN) forming the W-phase lower arm. The switching elements Tr1 to Tr6 thus provided are switched in response to a PWM signal output from the motor controller 92, thereby controlling the pulse width of the voltage applied from the battery 1 to the motor 4 (PWM control).

[0017] The switching circuits UP, UN, VP, VN, WP, and WN are provided with temperature sensors 31 to 36, respectively. The temperature sensors 31 to 36 detect the temperature of each switching circuit UP, UN, VP, VN, WP, and WN, that is, the temperature T up ,T un ,T vp ,T vn ,T wp ,T wn The detected element temperature T up ,T un ,T vp ,T vn ,T wp ,T wn (Hereafter, the detection temperature T dThe temperature sensors 31 to 36 detect the temperatures of the switching circuits UP, UN, VP, VN, WP, and WN, and these temperatures can be considered to be essentially the temperatures of the switching elements Tr1 to Tr6.

[0018] The motor 4 is a three-phase AC motor of a permanent magnet type with a permanent magnet in the rotor, and has an input section for each of the three phases (UVW phases). The motor 4 is a drive source that drives the drive wheels of the electric vehicle, and the drive wheels of the electric vehicle rotate as the motor 4 rotates.

[0019] The capacitor 5 is disposed between the relay 2 and the inverter 3, and is connected in parallel with the inverter 3. The capacitor 5 smoothes the DC power input from the battery 1 to the inverter 3.

[0020] The current sensors 6 measure the magnitude of each current flowing from the inverter 3 to the input section of each phase of the motor 4. In this embodiment, three current sensors, current sensors 6U, 6V, and 6W, are provided on the power supply lines to the input section of each phase of the motor 4. The current sensors 6U, 6V, and 6W output the measured three-phase AC currents Iu, Iv, and Iw of each phase to the motor controller 92, respectively.

[0021] The magnetic pole position detection sensor 7 is a sensor that detects the position of the rotor, and is, for example, a resolver or an encoder. The magnetic pole position detection sensor 7 is provided near the rotor of the motor 4 and measures the phase θ of the rotor of the motor 4. The rotor phase θ measured by the magnetic pole position detection sensor 7 is output to the motor controller 92 as a magnetic pole position sensor signal.

[0022] The cooling device 8 is a device for cooling the inverter 3. The cooling device 8 is configured by, for example, a water jacket or the like, and supplies cooling water to the switching elements Tr1 to Tr6 and the rectifying elements D1 to D6 of the inverter 3 to cool them. The cooling device 8 is provided with a temperature T w The cooling water temperature T detected by the cooling water temperature sensor 81 is provided. w is output to the motor controller 92 as a cooling water temperature signal.

[0023] The controller 9 is configured by a computer equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input / output interface (I / O interface), and programmed to be able to execute the processes described below. The controller 9 can also be configured by multiple computer hardware that executes the processes in a distributed manner. The controller 9 includes a vehicle controller 91 and a motor controller 92.

[0024] The vehicle controller 91 generates a torque command value T , which indicates a torque required of the motor 4, based on an accelerator signal, a brake signal, a shift position signal, etc. of the electric vehicle. * Calculate the torque command value T * to the motor controller 92. Furthermore, the vehicle controller 91 outputs a relay control signal to the relay 2 between the battery 1 and the inverter 3 to open or close the relay 2.

[0025] The motor controller 92 controls the operation of the inverter 3. The motor controller 92 outputs a torque command value T * , and generates a pulse width modulation (PWM) signal for defining the switching pattern (duty ratio) of each of the switching elements Tr1 to Tr6. More specifically, the motor controller 92 first receives the torque command value T *and the magnetic pole position sensor signal (rotor phase θ) output from the magnetic pole position detection sensor 7, the target supply current value (current command value) I to the motor 4 is calculated so as to realize the required torque. * Next, a current command value I is calculated based on the three-phase AC currents Iu, Iv, and Iw output from the current sensor 6. * The target supply power (voltage command value) to the motor 4 is calculated so that there is no deviation between the value of the current I flowing through the motor 4 and the voltage command value I. Then, a PWM signal is generated to realize the calculated voltage command value. The generated PWM signal is output to the gate drive circuit 10.

[0026] The motor controller 92 also estimates the temperatures of the switching elements Tr1 to Tr6 and calculates the estimated temperatures T es and the detected temperatures T of the switching elements Tr1 to Tr6. d Based on this, an abnormality (open-phase abnormality) of the inverter 3 is detected, and inverter abnormality detection control is executed. Details of the inverter abnormality detection control will be described later.

[0027] The gate drive circuit 10 controls the on / off of the switching elements Tr1 to Tr6 of the inverter 3 at a predetermined timing in response to a PWM signal input from the motor controller 92. This controls the pulse width of the voltage applied to the motor 4, and the torque command value T * It is possible to generate a torque of

[0028] Next, details of inverter abnormality detection control by the controller 9 (motor controller 92) will be described.

[0029] 2 is a block diagram showing the configuration of the inverter abnormality detection calculation process in the motor controller 92. As shown in FIG. 2, the motor controller 92 includes a current command value calculation unit 921, an estimated temperature calculation unit 922, a difference comparison unit 923, and an abnormality detection unit 924.

[0030] The current command value calculation unit 921 calculates the current command value I *The current command value calculation unit 921 calculates the torque command value T * , and a magnetic pole position sensor signal (rotor phase θ) from the magnetic pole position detection sensor 7. The current command value calculation unit 921 calculates the rotation speed (electrical angular velocity) ω obtained by differentially operating the rotor phase θ, and the torque command value T * Based on this, the current command value I * The current command value I calculated by the current command value calculation unit 921 is calculated. * is output to the estimated temperature calculation unit 922.

[0031] The estimated temperature calculation unit 922 estimates the element temperature of the inverter 3. The estimated temperature calculation unit 922 receives the current command value I * and the coolant temperature signal (coolant temperature T w ) is input to the estimated temperature calculation unit 922. * and cooling water temperature T w The element temperature (switching element temperature) of the inverter 3 is estimated based on the above. Note that any existing method may be used to specifically estimate the element temperature. The estimated element temperature (estimated temperature) T est is output to the difference comparison unit 923.

[0032] The difference comparison unit 923 compares the estimated temperature T est and the element temperature (detection temperature) T of inverter 3 d The difference ΔT d is a predetermined value (threshold) ΔT th The difference comparison unit 923 compares the estimated temperature T est and the element temperature sensor signals (detected temperatures) T from the temperature sensors 31 to 36. d (T up ,T un ,T vp ,T vn ,T wp ,T wn ) is input to the difference comparison unit 923. est and the detected temperature T dThe difference is calculated by comparing the difference with a predetermined value (threshold value) ΔT th Specifically, the difference comparison unit 923 determines whether the estimated temperature T est and the detected element temperature T up , the element temperature T of the U-phase lower arm un , V-phase upper arm element temperature T vp , V-phase lower arm element temperature T vn , the element temperature T of the upper arm of the W phase wp , W-phase lower arm element temperature T wn Then, the estimated temperature T est and the element temperature T up ,T un ,T vp ,T vn ,T wp ,T wn The difference ΔT up ,ΔT un ,ΔT vp ,ΔT vn ,ΔT wp ,ΔT wn (Hereafter, ΔT d (also called) is the threshold ΔT th A signal indicating the diagnosis result by the difference comparison unit 923 is output to the abnormality detection unit 924.

[0033] The abnormality detection unit 924 judges whether or not the inverter 3 is abnormal. The abnormality detection unit 924 receives a signal indicating the diagnosis result from the difference comparison unit 923. The abnormality detection unit 924 calculates the estimated temperature T est and the element temperature (detection temperature) of each arm T d The difference ΔT d However, continuously, the threshold ΔT th The number of times that the temperature is equal to or greater than the estimated temperature T est and the detected temperature T d The difference ΔT d is the threshold ΔT th The number of times that this occurs is a predetermined threshold k th If the temperature continues to exceed the estimated temperature T est and the element temperature T up ,Tun ,T vp ,T vn ,T wp ,T wn The difference ΔT up ,ΔT un ,ΔT vp ,ΔT vn ,ΔT wp ,ΔT wn Either of these is the number of times threshold k th continuously exceeding the threshold ΔT th If the temperature is equal to or greater than the estimated temperature T est and the element temperature (detection temperature) T of the U-phase upper arm up The difference ΔT up is the threshold k th continuously exceeding the threshold ΔT th If the temperature is equal to or greater than this, the abnormality detection unit 924 determines that the inverter 3 is abnormal. est and the element temperature T un The difference ΔT un , V-phase upper arm element temperature T vp The difference ΔT vp , V-phase lower arm element temperature T vn The difference ΔT vn , the element temperature T of the upper arm of the W phase wp The difference ΔT wp , W-phase lower arm element temperature T wn The difference ΔT wn is the threshold k th continuously exceeding the threshold ΔT th If this occurs, the abnormality detection unit 924 determines that the inverter 3 is abnormal (phase loss abnormality).

[0034] If it is determined that the inverter 3 is abnormal, the abnormality detection unit 924 notifies a passenger, such as the driver of the electric vehicle, of the abnormality of the inverter 3 by outputting an abnormality signal to a display unit or the like of the electric vehicle and displaying the signal. Note that the method of notifying a passenger, such as the driver, of the electric vehicle of the abnormality of the inverter 3 is not limited to this. Furthermore, the notification of the abnormality may specifically notify which arm element (switching element) of the inverter 3 has the abnormality. This allows more appropriate measures to be taken in response to the abnormality of the inverter 3.

[0035] In this embodiment, the estimated temperature T est and the detected temperature T d The difference ΔT d However, continuously, the threshold ΔT th If the number of times is equal to or greater than the threshold k th However, this is not necessarily limited to the above. For example, if the number of times exceeds the threshold value k th is not set, and the estimated temperature T est and the detected temperature T d The difference ΔT d is the threshold ΔT th If this is the case, it may be determined that the inverter 3 is abnormal.

[0036] As described above, in the inverter abnormality detection method of this embodiment, the estimated temperature T est and the detected temperature T of each switching element (element of each arm) d Then, the estimated temperature T est and the detected temperature T d Difference ΔT d is the threshold ΔT th In the above cases, it is determined that the inverter 3 is abnormal.

[0037] One method for determining whether an inverter consisting of multiple switching elements is to use the current integration value for the positive section and the current integration value for the negative section of each phase current. In this method, current is supplied from the inverter to the motor, and while the motor is running, the current of each phase of the motor and the magnetic pole position (angle) of the rotor are detected. Then, based on the detected current and the magnetic pole position of the rotor, the current integration value for the positive section and the current integration value for the negative section of each phase current are calculated, and these integration values are compared to determine whether the inverter is malfunctioning based on the comparison results. However, when using the current integration value for the positive section and the negative section, the magnetic pole position detection and the calculation of the current integration value must be processed quickly (the calculation cycle must be shortened) when the motor is rotating at high speed, where the current and angle frequencies are high. Shortening the calculation cycle in this way increases the calculation load on the controller.

[0038] In contrast to this, in this embodiment, the current command value I * and the temperature T of the cooling water that cools the inverter 3. w The temperature T of the switching element estimated based on est and the detected temperature T of each switching element d Difference ΔT d It is determined whether the inverter 3 is abnormal based on the estimated temperature T est and the detected temperature T of each switching element up ,T un ,T vp ,T vn ,T wp ,T wn Since an abnormality in the inverter 3 is detected from the calculation period, it is possible to detect an abnormality in the inverter 3 without shortening the calculation period even when the motor 4 is rotating at high speed. Therefore, it is possible to detect an abnormality in the inverter 3 without increasing the calculation load.

[0039] 3 is a flowchart illustrating the abnormality detection control of the inverter according to this embodiment. The following control is all repeatedly executed at predetermined time intervals by the controller 9. The controller 9 controls the three-phase AC currents Iu, Iv, and Iw, the rotor phase θ, and the element temperature T of each arm. up ,T un ,T vp ,T vn ,T wp ,T wn , cooling water temperature T w , accelerator signal, brake signal, shift position signal, etc. are acquired as appropriate.

[0040] When the vehicle system including the abnormality detection system 100 is started, for example, by turning on the ignition switch, the controller 9 starts the abnormality detection control of the inverter.

[0041] In step S101, the controller 9 calculates a torque command value T * Calculate.

[0042] In step S102, the controller 9 calculates the torque command value T * and the rotor phase θ, the current command value I * Calculate.

[0043] In step S103, the controller 9 calculates the current command value I * and cooling water temperature T w Based on this, the estimated temperature T est Calculate.

[0044] In step S104, the controller 9 calculates the element temperature (detected temperature) T d (T up ,T un ,T vp ,T vn ,T wp ,T wn ) for the estimated temperature T est The absolute value of the difference (hereinafter referred to as the temperature difference) ΔT d(ΔT up ,ΔT un ,ΔT vp ,ΔT vn ,ΔT wp ,ΔT wn Specifically, the element temperature and estimated temperature T est Absolute value of the difference ΔT up ,ΔT un ,ΔT vp ,ΔT vn ,ΔT wp ,ΔT wn Calculate.

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[0045] In step S105, the controller 9 calculates the temperature difference ΔT d is the threshold ΔT th Determine whether the temperature difference is greater than or equal to ΔT. d is the threshold ΔT th In the above cases, the controller 9 determines that the inverter 3 is abnormal and d is the threshold ΔT th If the threshold ΔT is less than 1 / 2, the controller 9 determines that the inverter 3 is not abnormal (is normal) or is currently being determined to be abnormal. In detail, the controller 9 executes the abnormality diagnosis process shown in steps S111 to S129 in FIG. 4. this the accuracy of the temperature sensors 31 to 36, the temperature values acquired by the temperature sensors 31 to 36, and the temperature value T estimated by calculation. est It can be determined in advance based on experimental data comparing the above.

[0046] In step S111, the controller 9 calculates the element temperature T up and the estimated temperature T est Temperature difference ΔT up is the threshold ΔT th Determine whether the temperature difference is greater than or equal to ΔT. up is the threshold ΔT th If the temperature difference ΔT is equal to or greater than the predetermined value, the controller 9 executes the process of step S112. up is the threshold ΔT th If it is less than the predetermined value, the controller 9 executes the process of step S113.

[0047] In step S112, the controller 9 determines that the U-phase upper arm is abnormal (open-phase abnormality) and counts up the abnormality counter k up Count up (+1) the abnormality counter k up After counting up, the controller 9 executes the process of step S114.

[0048] Temperature difference ΔT up is the threshold ΔT th If it is less than the value, in step S113, the controller 9 determines that the U-phase upper arm is not abnormal (is normal), and up Clear (set to 0) the abnormality counter k up When the value is cleared, the controller 9 executes the process of step S114.

[0049] In step S114, the controller 9 calculates the element temperature T un and the estimated temperature T est Temperature difference ΔT un is the threshold ΔT th Determine whether the temperature difference is greater than or equal to ΔT. un is the threshold ΔT thIf the temperature difference ΔT is equal to or greater than the predetermined value, the controller 9 executes the process of step S115. un is the threshold ΔT th If it is less than the predetermined value, the controller 9 executes the process of step S116.

[0050] In step S115, the controller 9 determines that the U-phase lower arm is abnormal (open-phase abnormality) and counts up the abnormality counter k un Count up (+1) the abnormality counter k un After counting up, the controller 9 executes the process of step S117.

[0051] Temperature difference ΔT un is the threshold ΔT th If it is less than the normal value, in step S116, the controller 9 determines that the U-phase lower arm is not abnormal (is normal), and un Clear (set to 0) the abnormality counter k un When the value is cleared, the controller 9 executes the process of step S117.

[0052] In step S117, the controller 9 calculates the element temperature T vp and the estimated temperature T est Temperature difference ΔT vp is the threshold ΔT th Determine whether it is greater than or equal to the threshold ΔT th If the value is equal to or greater than this, the controller 9 determines that the V-phase upper arm is abnormal (open-phase abnormality), and in step S118, the abnormality counter k vn is counted up (+1) and the process of step S120 is executed. th If the value is less than the threshold value, the controller 9 determines that the V-phase upper arm is not abnormal (is normal), and counts up the abnormality counter k vp is cleared, and the process of step S120 is executed.

[0053] In step S120, the controller 9 calculates the element temperature Tvn and the estimated temperature T est Temperature difference ΔT vn is the threshold ΔT th Determine whether it is greater than or equal to the threshold ΔT th If the value is equal to or greater than this, the controller 9 determines that the V-phase lower arm is abnormal (open-phase abnormality) and increments the abnormality counter k in step S121. vn is counted up (+1), and the process of step S123 is executed. th If the value is less than the threshold value, the controller 9 determines that the V-phase lower arm is not abnormal (is normal), and in step S122, the controller 9 increments the abnormality counter k vp is cleared, and the process of step S123 is executed.

[0054] In step S123, the controller 9 controls the W-phase upper arm to wp and the estimated temperature T est Temperature difference ΔT wp is the threshold ΔT th Determine whether it is greater than or equal to the threshold ΔT th If the value is equal to or greater than this, the controller 9 determines that the W-phase upper arm is abnormal (open-phase abnormality) and increments the abnormality counter k wp is counted up (+1), and the process of step S123 is executed. th If the value is less than the value indicated by the error signal, the controller 9 determines that the W-phase upper arm is not abnormal (is normal), and in step S125, the controller 9 increments the abnormality counter k wp is cleared, and the process of step S126 is executed.

[0055] In step S126, the controller 9 controls the W-phase lower arm to wn and the estimated temperature T est Temperature difference ΔT wn is the threshold ΔT th Determine whether it is greater than or equal to the threshold ΔT th If the value is equal to or greater than this, the controller 9 determines that the W-phase lower arm is abnormal (open-phase abnormality) and increments the abnormality counter k wnis counted up (+1), and the process of step S129 is executed. th If the value is less than the value indicated by the error signal, the controller 9 determines that the W-phase upper arm is not abnormal (is normal), and in step S128, the controller 9 increments the abnormality counter k wn is cleared, and the process of step S129 is executed.

[0056] In step S129, the controller 9 counts the abnormality counter k(k up ,k un ,k vp ,k vn ,k wp ,k wn ) is the threshold value k th It is determined whether the abnormality counter k of any arm exceeds the threshold value k th If the abnormality counter k of each arm exceeds the threshold, the controller 9 determines that the abnormal state continues and that the inverter 3 is abnormal. up ,k un ,k vp ,k vn ,k wp ,k wn are all within the threshold k th In the following cases, the controller 9 determines that the abnormality of the arm has not continued long enough to determine an abnormal state, and determines that the inverter 3 is normal or is in the process of being determined to be abnormal. th can be determined in advance through experiments or the like based on the time interval from the occurrence of an abnormality until the occurrence of a dangerous event, the probability of misdiagnosis of an abnormality, and the like.

[0057] Returning to step S105 (FIG. 3), if it is determined in the abnormality diagnosis process (steps S111 to S129) that the inverter 3 is abnormal, the controller 9 notifies the abnormality via a display unit or the like of the electric vehicle, and terminates the inverter abnormality detection control. As described above, when notifying the abnormality, it may also be configured to notify which specific arm (switching element) has the abnormality.

[0058] On the other hand, if it is determined in the abnormality diagnosis processing (steps S111 to S129) that the inverter 3 is normal or is being determined to be abnormal, the controller 9 ends the inverter abnormality detection control and starts the processing again from step S101 after a predetermined time.

[0059] Although the abnormality diagnosis process (steps S111 to S129) has been described in the order beginning with the diagnosis of the U-phase upper arm, the order of the abnormality diagnosis of each phase arm may be arbitrary, and the diagnosis may also be performed simultaneously in parallel. That is, the processing of steps S111 to S113, steps S114 to S116, steps S117 to S119, steps S120 to S122, steps S123 to S125, and steps S126 to S128 may be performed in any order, and may also be performed simultaneously.

[0060] According to the inverter abnormality detection method of the first embodiment described above, the following effects can be obtained.

[0061] According to the inverter abnormality detection method of this embodiment, the current command value I * and the temperature T of the cooling water that cools the inverter 3. w The temperature of the switching element is estimated based on the estimated temperature T est and the detected temperature T of each switching element d (T up ,T un ,T vp ,T vn ,T wp ,T wn ) and the difference ΔT d is a predetermined value (threshold) ΔT th In the above cases, it is determined that the inverter 3 is abnormal. est and the detected temperature T of each switching element up ,T un ,T vp ,T vn ,T wp ,T wnSince an abnormality in the inverter 3 is detected from the calculation period, it is possible to detect an abnormality in the inverter 3 without shortening the calculation period even when the motor 4 is rotating at high speed. Therefore, it is possible to detect an abnormality in the inverter without increasing the calculation load.

[0062] In addition, the estimated temperature T est and the detected temperature T of each switching element up ,T un ,T vp ,T vn ,T wp ,T wn Since an abnormality in the inverter 3 is detected from the information, it is possible to determine which switching element has an abnormality. Therefore, by notifying the occupants etc. of which switching element has an abnormality, the occupants etc. can take more appropriate measures to deal with the abnormality in the inverter 3.

[0063] [Second embodiment] 5 to 7, a schematic configuration diagram of an inverter abnormality detection system 100 according to a second embodiment will be shown. Note that the same elements as those in the first embodiment are given the same reference numerals, and the description thereof will be omitted.

[0064] 5 is a block diagram showing the configuration of a motor controller 92 in the second embodiment. This embodiment differs from the first embodiment in that the abnormality detection system 100 includes a delay correction unit 925.

[0065] As shown in FIG. 5, the motor controller 92 in this embodiment calculates the element temperature (estimated temperature) T est is input to the delay correction unit 925.

[0066] The delay correction unit 925 calculates the estimated temperature T est Then, delay correction is performed on the estimated temperature T est ´ to the difference comparison unit 923. That is, the temperature T up,T un ,T vp ,T vn ,T wp ,T wn When detecting the estimated temperature T, a time lag may occur between the time of measurement by the temperature sensors 31 to 36 and the time of detection due to a delay in the response of the sensors. est is the current command value I * is estimated based on the current command value I * When calculating the current command value I * The operation of each switching element is controlled according to the detected temperature T d is the estimated temperature T est Therefore, the delay correction unit 925 corrects the estimated temperature T est By performing delay correction on the sensor, the response delay of the sensor to the actual temperature change of the switching element is corrected to the estimated temperature T est can also be reflected in

[0067] For example, as shown in Figure 6, the estimated temperature T est By performing delay correction, the response delay of the temperature sensor 31 in the U-phase upper arm is corrected to the estimated temperature T est In the other arms, the response delay of the temperature sensors 32 to 36 in each arm is also reflected in the estimated temperature T est , allowing for a more accurate comparison of the estimated temperature with the detected temperature.

[0068] The amount of delay correction can be determined in advance through experiments, etc. A specific correction method is, for example, to apply a first-order delay low-pass filter or other filters.

[0069] The difference comparison unit 923 calculates the corrected estimated temperature T est ´ The difference comparison unit 923 receives the corrected estimated temperature T est ´ and the detected temperature Td The difference ΔT d is the threshold ΔT th The diagnosis result in the difference comparison unit 923 is output to the abnormality detection unit 924, and the estimated temperature T est ´ and the detected temperature T d The difference ΔT d is the threshold ΔT th If the number of times is equal to or greater than the threshold k th If it exceeds this value, the abnormality detection unit 924 determines that the inverter 3 is abnormal.

[0070] 7 is a flowchart illustrating inverter abnormality detection control according to the second embodiment. As in the first embodiment, the following controls are all repeatedly executed by the controller 9 at predetermined time intervals.

[0071] Steps S101 to S103 are the same as those in the first embodiment, and therefore the explanation will be omitted.

[0072] In step S103, the estimated temperature T est , the controller 9 calculates the estimated temperature T est Then, delay correction is performed on the estimated temperature T est ´ Get.

[0073] Steps S104 to S105 are the same as those in the first embodiment, and therefore the explanation will be omitted. However, in step S104, the element temperature (detected temperature) T d and the estimated temperature T est When calculating the absolute value of the difference between the estimated temperature T est ´ That is, in step S104, the element temperature (detected temperature) T d and the estimated temperature after correction T est ´ Absolute value of the difference ΔT d Calculate.

[0074] As described above, in this embodiment, the estimated temperature T est After performing delay correction, the estimated temperature T est ´ and the detected temperature T d This compares the estimated temperature with the detected temperature T d Therefore, it is possible to more accurately compare the threshold ΔT used to determine whether the inverter 3 is abnormal. th This can reduce the margin for preventing misdiagnosis that is taken into consideration when determining the abnormality of the inverter 3, thereby improving the accuracy of detecting abnormalities in the inverter 3.

[0075] [Third embodiment] 8 to 10, a schematic configuration diagram of an inverter abnormality detection system 100 according to a third embodiment will be shown. Elements similar to those in the other embodiments will be given the same reference numerals, and descriptions thereof will be omitted.

[0076] 8 is a block diagram showing the configuration of a motor controller 92 in the third embodiment. This embodiment differs from the first embodiment in that the abnormality detection system 100 includes a lead compensation unit 926.

[0077] As shown in FIG. 8, the motor controller 92 in this embodiment includes a lead compensation unit 926. The lead compensation unit 926 detects the element temperature (detected temperature) T up ,T un ,T vp ,T vn ,T wp ,T wn is entered.

[0078] The lead compensation unit 926 detects the detected temperature T d (T up ,T un ,T vp ,T vn ,T wp ,T wn) is corrected by adding a phase lead compensation taking into account the response delay of the temperature sensors 31 to 36, and the corrected detected temperature T d ´ (T up ´ ,T un ´ ,T vp ´ ,T vn ´ ,T wp ´ ,T wn ´ ) to the difference comparison unit 923. That is, as described above, due to the response delay of the sensor, etc., the detected temperature T d is the estimated temperature T est Therefore, the lead compensation unit 926 may cause a delay in the detection temperature T d By adding lead compensation to the sensor, the response delay of the sensor to the actual temperature change of the switching element is corrected.

[0079] For example, as shown in Figure 9, the detected temperature T up By adding phase lead compensation to the temperature sensor 31 in the U-phase upper arm, the response delay of the temperature sensor 31 can be corrected, and the estimated temperature can be compared more accurately with the detected temperature. d By adding phase lead compensation to the temperature sensors 32 to 36 in each arm, the response delays and the like are corrected, and the difference comparison unit 923 can compare the estimated temperature with the detected temperature more accurately.

[0080] The correction amount of lead compensation can be determined in advance by experiment, etc. Also, the lead compensation to be added is determined individually for each arm, and the detected temperature T d (T up ,T un ,T vp ,T vn ,T wp ,T wn) may be individually determined and subjected to lead compensation. This allows the difference comparison unit 923 to compare the estimated temperature and the detected temperature more accurately. A specific correction method can be implemented, for example, by applying a phase lead compensation filter or other filters.

[0081] The difference comparator 923 receives the corrected detected temperature T d ´ (T up ´ ,T un ´ ,T vp ´ ,T vn ´ ,T wp ´ ,T wn ´ ) is input to the difference comparison unit 923. est and the corrected detected temperature T d ´ The difference ΔT d is the threshold ΔT th The diagnosis result in the difference comparison unit 923 is output to the abnormality detection unit 924, and the estimated temperature T est and the corrected detected temperature T d ´ The difference ΔT d is the threshold ΔT th If the number of times is equal to or greater than the threshold k th If it exceeds this value, the abnormality detection unit 924 determines that the inverter 3 is abnormal.

[0082] 10 is a flowchart illustrating inverter abnormality detection control according to the third embodiment. As in the other embodiments, the following controls are all repeatedly executed by the controller 9 at predetermined time intervals.

[0083] Steps S101 to S103 are the same as those in the first embodiment, and therefore the explanation will be omitted.

[0084] In step S303, the controller 9 calculates the element temperature (detected temperature) Td (T up ,T un ,T vp ,T vn ,T wp ,T wn ) is corrected by adding lead compensation, and the corrected detected temperature T d ´ (T up ´ ,T un ´ ,T vp ´ ,T vn ´ ,T wp ´ ,T wn ´ ) to get the

[0085] Steps S104 to S105 are the same as those in the first embodiment, and therefore the explanation will be omitted. However, in step S104, the element temperature (detected temperature) T d and the estimated temperature T est When calculating the absolute value of the difference between the corrected detected temperature T d ´ (T up ´ ,T un ´ ,T vp ´ ,T vn ´ ,T wp ´ ,T wn ´ That is, in step S104, the corrected element temperature (detected temperature) T d ´ (T up ´ ,T un ´ ,T vp ´ ,T vn ´ ,T wp ´ ,T wn ´ ) and the estimated temperature T est Absolute value of the difference ΔT d Calculate.

[0086] As described above, in this embodiment, the element temperature (detected temperature) T up ,T un ,T vp ,T vn ,T wp ,T wn The estimated temperature T est and the corrected detected temperature T d ´ (T up ´ ,T un ´ ,T vp ´ ,T vn ´ ,T wp ´ ,T wn ´ ) is compared. This allows for a more accurate comparison between the estimated temperature and the detected temperature. Therefore, the probability of misdiagnosis can be reduced when determining whether or not the inverter 3 is abnormal. In addition, since the probability of misdiagnosis is reduced, the threshold value ΔT used when determining whether or not the inverter 3 is abnormal can be reduced. th This can reduce the margin for preventing misdiagnosis that is taken into consideration when determining the abnormality of the inverter 3, thereby improving the accuracy of detecting abnormalities in the inverter 3.

[0087] Furthermore, since the lead compensation to be added can be determined individually for each arm, the estimated temperature can be compared more accurately with the detected temperature.

[0088] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

[0089] Although the above-described embodiments have been described as separate embodiments, they may be combined as appropriate. [Explanation of symbols]

[0090] 1: Battery, 3: Inverter, 31 to 36: Temperature sensors, 4: Motor, 6: Current sensor, 7: Magnetic pole position detection sensor, 8: Cooling device, 81: Cooling water temperature sensor (temperature sensor), 9: Controller, 91: Vehicle controller, 92: Motor controller, 100: Abnormality detection system

Claims

1. A method for detecting an abnormality in an inverter that converts DC power from a power source into AC power and supplies the AC power to a motor, comprising: the inverter includes a plurality of switching elements; calculating a current command value for controlling operation of the plurality of switching elements based on the required torque of the motor; Detecting the temperature of each switching element and the temperature of cooling water that cools the inverter; estimating a temperature of a switching element based on the current command value and the temperature of the cooling water; If the difference between the estimated temperature of the switching element and the detected temperature of each switching element is equal to or greater than a predetermined value, it is determined that the inverter is abnormal. A method for detecting inverter abnormalities.

2. 2. The inverter abnormality detection method according to claim 1, A delay correction is performed on the estimated temperature of the switching element, and if the difference between the estimated temperature of the switching element after the correction and the detected temperature of each switching element is equal to or greater than the predetermined value, it is determined that an abnormality has occurred. A method for detecting inverter abnormalities.

3. 2. The inverter abnormality detection method according to claim 1, A correction is made by adding a phase lead compensation to the detected temperature of each switching element, and if the difference between the detected temperature of each switching element after the correction and the estimated temperature of the switching element is equal to or greater than the predetermined value, it is determined that an abnormality has occurred. A method for detecting inverter abnormalities.

4. A motor; an inverter including a plurality of switching elements, which converts DC power from a power supply into AC power and supplies the AC power to the motor; a temperature sensor for detecting the temperature of each switching element of the inverter; a cooling device that supplies cooling water to the inverter to cool each switching element; a temperature sensor for detecting the temperature of the cooling water; a controller that calculates a current command value based on a required torque of the motor and transmits the current command value to the inverter, the controller estimates the temperature of the switching elements of the inverter based on the current command value and the temperature of the cooling water, and determines that the inverter is abnormal if a difference between the estimated temperature of the switching elements and the detected temperature of each switching element is equal to or greater than a predetermined value; Inverter abnormality detection system.

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