Vehicle control system

Abstract

The present invention provides a vehicle control device that can continue driving the motor and preventing secondary failures, even when the inverter fails, while protecting the motor coils. [Solution] The vehicle control device comprises a motor for vehicle travel driven by an n-phase (n is a natural number of 3 or more) alternating current, an inverter that drives the motor, an inverter abnormality determination unit that determines an abnormality in the inverter, and a drive system abnormality determination unit that determines an abnormality in the drive system including the motor and inverter when the inverter abnormality determination unit determines an abnormality in the inverter and the rate of temperature change of at least one of the cables supplying power to each phase of the motor exceeds a threshold value. The drive system abnormality determination unit sets the threshold value to a smaller value than when it determines that at least one of the temperature sensors installed on each of the cables is malfunctioning.

Description

Technical Field

[0001] The present invention relates to a vehicle control device.

Background Art

[0002] As a vehicle control device for running a vehicle, there has been proposed one including a three-phase motor and an inverter for driving the three-phase motor, which detects a switching element that has an open fault among a plurality of switching elements of the inverter based on the respective integrated values of the currents flowing through each phase of the three-phase motor (see, for example, Patent Document 1). In this vehicle control device, even when an open fault of any switching element is detected, it is possible to generate some torque in most regions from the three-phase motor by continuing vector control with the synthetic voltage vector fixed. Further, there has been proposed a vehicle control device that includes fuses in the minus-side wiring of each phase of the motor, the inverter, and the inverter, and short-circuits the three phases when the fuse blows due to an excessive current based on a short-circuit fault or malfunction of the switching element of the inverter (see, for example, Patent Document 2). In this vehicle control device, irreversible demagnetization of the magnets of the motor that may occur when an abnormality of the inverter occurs during high-speed rotation of the motor is suppressed.

Prior Art Documents

Patent Documents

[0003] <000​​​​​​​​​​​​​​​​When such a vehicle control system is adopted, it is necessary to drive the motor in order to move the train to safety even if the inverter fails. However, if the motor is driven when the inverter has failed, secondary failures such as irreversible demagnetization of the motor may occur, as described above.

[0005] This invention was made to solve such problems and provides a vehicle control device that can continue driving the motor and causing secondary failures while protecting the motor coils even when the inverter fails. [Means for solving the problem]

[0006] A vehicle control device in a specific embodiment of the present invention comprises a motor for vehicle travel driven by an n-phase (n is a natural number of 3 or more) alternating current, an inverter for driving the motor, an inverter abnormality determination unit for determining an abnormality in the inverter, and a drive system abnormality determination unit for determining an abnormality in the drive system including the motor and inverter when the inverter abnormality determination unit has determined an abnormality in the inverter and the rate of temperature change of at least one of the cables supplying power to each phase of the motor exceeds a threshold value, wherein the drive system abnormality determination unit sets the threshold value to a smaller value than when it is determined that there is no malfunction if it determines that at least one of the temperature sensors installed on each of the cables is malfunctioning. [Effects of the Invention]

[0007] The present invention provides a vehicle control device that can continue driving the motor and preventing secondary failures even when the inverter fails, while protecting the motor coil. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram shows a schematic configuration of the vehicle control device according to this embodiment. [Figure 2] This is an explanatory diagram showing an example of a control block diagram for rectangular wave control performed by an electronic control unit. [Figure 3]This is an explanatory diagram illustrating the relationship between the motor torque output from the motor and the motor speed, as well as the drive region in which square wave control is performed. [Figure 4] This flowchart shows an example of an anomaly detection routine executed by an electronic control unit. [Modes for carrying out the invention]

[0009] The present invention will be described below through embodiments, but the claims are not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential for solving the problem.

[0010] Figure 1 is a schematic diagram showing the configuration of the vehicle control device 120 according to this embodiment. The vehicle control device 120 mainly comprises a motor 130, an inverter 132, a battery 134, a boost converter 136, a system main relay 138, a resolver 140, a U-phase cable temperature sensor 142U, a V-phase cable temperature sensor 142V, a W-phase cable temperature sensor 142W, a V-phase cable current sensor 144V, a W-phase cable current sensor 144W, and an electronic control unit 50.

[0011] Motor 130 is a motor for vehicle propulsion driven by three-phase AC power. Inverter 132 drives motor 130 by switching multiple switching elements on and off. Battery 134 is a secondary battery that supplies power to vehicle control device 120. Boost converter 136 converts voltage between the low-voltage side to which battery 134 is connected and the high-voltage side to which inverter 132 is connected. System main relay 138 connects and disconnects battery 134 and boost converter 136.

[0012] The resolver 140 detects the rotational position θ of the rotor of the motor 130. The U-phase cable temperature sensor 142U detects the temperature Tu of the U-phase cable 131U connected to the U-phase coil that makes up the motor 130. The V-phase cable temperature sensor 142V detects the temperature Tv of the V-phase cable 131V connected to the V-phase coil that makes up the motor 130. The W-phase cable temperature sensor 142W detects the temperature Tw of the W-phase cable 131W connected to the W-phase coil that makes up the motor 130. The V-phase cable current sensor 144V detects the phase current iv flowing through the V-phase cable 131V. The W-phase cable current sensor 144W detects the phase current iw flowing through the W-phase cable 131W. The electronic control unit 50 receives the rotational position θ, temperature Tu, Tv, temperature Tw, and phase currents iv and iv as inputs, and outputs control signals to control the inverter 132, the boost converter 136, and the system main relay 138.

[0013] In this embodiment, the vehicle control device 120 drives the motor 130 by square wave control when the rotational speed of the motor 130 is relatively high. Figure 2 is an explanatory diagram showing an example of a control block diagram of square wave control performed by the electronic control unit 150, and Figure 3 is an explanatory diagram for explaining the drive region in which square wave control is performed and the relationship between the motor torque output from the motor 130 and the motor rotational speed.

[0014] When performing square wave control, the electronic control unit 150 converts the phase currents iv and iw from the current sensors 144V and 144W and the rotational position θ from the resolver 140 into the d-axis current id and q-axis current iq, as shown in Figure 2. Based on the converted d-axis current id and q-axis current iq, it calculates an estimated value of the torque output from the motor 130 (hereinafter referred to as the estimated torque Trq).

[0015] Next, feedback control based on the difference ΔTrg between the torque command Trqcom (the torque to be output from the motor 130) and the estimated torque Trq is used to set the target voltage phase φtmp of the rectangular wave voltage applied to the motor 130 so that the estimated torque Trq approaches the torque command Trqcom. The target voltage phase φtmp is then limited by phase limiters φmin and φmax, which are upper and lower limits of the voltage phase allowed for control, to set the voltage phase command φ*. Finally, switching control of the switching elements of the inverter 132 is performed so that a rectangular wave voltage corresponding to the voltage phase command φ* is applied to the motor 130.

[0016] Here, the motor torque output from motor 130 is 0 when the voltage phase of the rectangular wave voltage applied to motor 130 is 0, increases as the voltage phase increases when the voltage phase is greater than 0, and reaches a maximum at a predetermined positive voltage phase according to the specifications of motor 130, and decreases as the voltage phase decreases when the voltage phase is less than 0, and reaches a minimum (maximum as a negative value) at a predetermined negative voltage phase according to the specifications of motor 130. The vehicle control device 120 of this embodiment drives motor 310 by rectangular wave control that utilizes these characteristics of motor 130 so that the torque output from motor 130 approaches the torque command Trqcom.

[0017] Furthermore, the phase limiter φmax can be set to a value less than or equal to the voltage phase when the motor torque is at its maximum, and the phase limiter φmin can be set to a value greater than or equal to the voltage phase when the motor torque is at its minimum. In this embodiment, the torque command Trqcom is set within a range of a rectangular wave control region where the voltage phase is less than or equal to the allowable maximum torque, which is smaller than the motor torque when the voltage phase is at the phase limiters φmin and φmax (torque at the phase limiter), so that the target voltage phase φtmp set by feedback control does not continuously exceed the phase limiters φmin and φmax (see Figure 3). Therefore, when the vehicle control device 120 is operating normally, the target voltage phase φtmp may transiently exceed the phase limiters φmin and φmax if the torque command Trqcom changes suddenly, but it will not continuously exceed the phase limiters φmin and φmax.

[0018] Next, we will describe the processing of the abnormality detection routine that determines abnormalities in the inverter 132 and abnormalities in the entire drive system including the inverter 132 and the motor 130. Figure 4 is a flowchart showing an example of an abnormality detection routine executed by the electronic control unit 150.

[0019] When the abnormality determination routine is started, the electronic control unit 150 starts its process as an inverter abnormality determination unit that determines an abnormality in the inverter 132. Specifically, in step S101, the electronic control unit 150 inputs a voltage phase command φ*, and in the subsequent step S102, it checks whether the voltage phase command φ* is equal to either the phase limiter φmin or φmax in order to determine whether an abnormality may have occurred in the inverter 132. When one of the switching elements of the inverter 132 has an open fault, the absolute value of the estimated torque Trq becomes small, the absolute value of the deviation ΔTrg becomes large, and the target voltage phase φtmp exceeds the phase limiters φmin and φmax by the above feedback control, so the voltage phase command φ* is limited by the phase limiters φmin and φmax. Therefore, by checking whether the voltage phase command φ* is equal to either the phase limiter φmin or φmax, it is possible to determine whether an abnormality may have occurred in the inverter 132.

[0020] When the voltage phase command φ* is not equal to either the phase limiter φmin or φmax, it is determined that no abnormality has occurred in the inverter 132, the value of the abnormality counter C is reset to 0 in step S103, and the process returns to step S101. When the voltage phase command φ* is equal to either the phase limiter φmin or φmax, it is determined that an abnormality may have occurred in the inverter 132, and the value of the abnormality counter C is incremented in step S104. Further, in step S105, the abnormality counter C is compared with a threshold Cref for inverter abnormality determination. If the abnormality counter C does not exceed the threshold Cref, the processes of steps S101 to S105 are repeated. If the abnormality counter C exceeds the threshold Cref, the process proceeds to step S106.

[0021] The electronic control unit 150 proceeds to step S106. When it determines that an abnormality has occurred in the inverter 132, it starts its processing as a drive system abnormality determination unit that determines an abnormality in the drive system including the motor 130 and the inverter 132. At this time, the electronic control unit 150 starts drive control for evacuation running from normal running until safely stopping in parallel with the processing of the abnormality determination routine.

[0022] When starting the processing as the drive system abnormality determination unit, the electronic control unit 150 proceeds to step S107 and inputs the cable temperatures Tu, Tv, and Tw, which are the output values of the U-phase cable temperature sensor 142U, the V-phase cable temperature sensor 142V, and the W-phase cable temperature sensor 142W, respectively. Immediately after starting the processing as the drive system abnormality determination unit, the cable temperatures Tu, Tv, and Tw are continuously input after a certain time.

[0023] The electronic control unit 150 proceeds to step S108 and determines whether a failure has occurred in any of the U-phase cable temperature sensor 142U, the V-phase cable temperature sensor 142V, and the W-phase cable temperature sensor 142W based on the acquired cable temperatures Tu, Tv, and Tw. If it determines that no failure has occurred, it proceeds to step S109, substitutes the value of the threshold Ref0 applied when there is no failure into the threshold ΔTref for drive system abnormality determination, and proceeds to step S111. If it determines that a failure has occurred, it proceeds to step S110, substitutes the value of the threshold Ref1 applied during a failure into the threshold ΔTref for drive system abnormality determination, and proceeds to step S111.

[0024] Here, Ref0 and Ref1, used as threshold values ​​ΔTref, are threshold values ​​for the rate of change of the cable temperature used to determine that the drive system, including the motor 130 and inverter 132, is abnormal before irreversible demagnetization of the motor 130's magnet occurs. These threshold values ​​are determined based on the rate of change of the cable temperature at which irreversible demagnetization of the motor 130 is expected to occur (as described later, Ref0 is determined based on the short-circuited cable, and Ref1 is determined based on the non-short-circuited cable). These threshold values ​​change depending on the specifications of the motor 130 and the characteristics of the connected cable, and are determined, for example, through prior trial and error.

[0025] In this embodiment, the value of the threshold ΔTref is set differently depending on whether all the cable temperature sensors for each phase are functioning normally (step S108 → step S109) or whether at least one of them is malfunctioning (step S108 → step S110). This is because, if the inverter malfunctions and one of the switching elements supplying current to the U, V, or W phases experiences an open fault and short circuit, the rate of temperature change expected to reach the temperature at which irreversible demagnetization of the motor 130 occurs will differ between the short-circuited phase and the other non-short-circuited phases during subsequent motor driving.

[0026] In other words, since the cable temperature in the short-circuit phase tends to rise, a relatively large value can be set as the threshold ΔTref. However, the cable temperature in the non-short-circuit phase does not tend to change abruptly, so when detecting these cable temperatures and observing their rate of change, it is necessary to set a smaller value as the threshold ΔTref compared to the case of the short-circuit phase.

[0027] If all the cable temperature sensors for each phase are functioning normally, even if a relatively large value is set as the threshold ΔTref, it is possible to correctly determine whether or not the temperature at which irreversible demagnetization of the motor 130 occurs is reached based on the rate of temperature change detected by the cable temperature sensor that detects the cable temperature of the short-circuit phase. On the other hand, if the cable temperature sensor that detects the cable temperature of the short-circuit phase is faulty, setting a relatively large value as the threshold ΔTref will make it impossible to correctly determine whether or not the temperature at which irreversible demagnetization of the motor 130 occurs is reached based on the rate of temperature change detected by the cable temperature sensor that detects the cable temperature of the non-short-circuit phase. Therefore, in this embodiment, as described above, if all the cable temperature sensors for each phase are functioning normally, the rate of temperature change of the cable of the short-circuit phase is calculated by one of the cable temperature sensors, so a relatively large value (=threshold Ref0) is adopted as the threshold ΔTref. If even one of them is faulty, considering that it may be the cable temperature sensor of the short-circuit phase, a relatively small value (=threshold Ref1 < threshold Ref0) is adopted as the threshold ΔTref. Furthermore, whether the cable temperature sensor is functioning correctly or malfunctioning can be determined, for example, by examining the acquired cable temperature values ​​Tu, Tv, and Tw themselves, or whether the changes in each value over time deviate from a preset range.

[0028] When the electronic control unit 150 proceeds to step S111, it calculates the temperature change rates ΔTu, ΔTv, and ΔTw, which are the temperature changes per unit time, from the cable temperatures Tu, Tv, and Tw acquired this time and the cable temperatures Tu, Tv, and Tw acquired last time. Then, it compares each of the calculated temperature change rates ΔTu, ΔTv, and ΔTw with a threshold ΔTref for determining drive system abnormalities and checks whether any one of them exceeds the threshold ΔTref.

[0029] If the electronic control unit 150 confirms in step S111 that none of ΔTu, ΔTv, or ΔTw exceed the threshold ΔTref, it returns to step S107 and repeats steps S107 through S111 at regular intervals. If it confirms that at least one of ΔTu, ΔTv, or ΔTw exceeds the threshold ΔTref, it proceeds to step S112, determines that the drive system is abnormal, and terminates the abnormality determination routine. When the electronic control unit 150 determines that the drive system is abnormal and terminates the abnormality determination routine, it gradually reduces the rotational speed of the motor 130 to stop the vehicle and terminates the control of the retraction run. By performing control in this manner, the motor coil of the motor 130 can be protected while ensuring a longer distance for the retraction run.

[0030] The embodiment described above describes a configuration in which there is no temperature sensor to detect the temperature of the motor 130 itself. However, the vehicle control device 120 may be configured to include a temperature sensor to detect the temperature of the motor 130. In that case, the abnormality of the drive system may be determined by checking whether the motor 130 has exceeded a threshold temperature based on the output of the temperature sensor. In such a device configuration, the abnormality determination process of the drive system using the above-mentioned temperature change rates ΔTu, ΔTv, and ΔTw may be performed as an auxiliary process to be executed when the temperature sensor is damaged.

[0031] Furthermore, although the vehicle control device 120 in this embodiment uses a three-phase AC motor as the motor 130, the AC motors that can be used are not limited to this. Even if the vehicle control device 120 uses a motor with more than three phases, the electronic control unit 150 can perform abnormality detection processing of the drive system using the rate of temperature change by inputting the temperature of each phase. [Explanation of Symbols]

[0032] 120... Vehicle control device, 130... Motor, 131U... U-phase cable, 131V... V-phase cable, 131W... W-phase cable, 132... Inverter, 134... Battery, 136... Boost converter, 138... System main relay, 140... Resolver, 142U... U-phase cable temperature sensor, 142V... V-phase cable temperature sensor, 142W... W-phase cable temperature sensor, 144V... V-phase cable current sensor, 144W... W-phase cable current sensor, 150... Electronic control unit

Claims

[Claim 1] A motor for vehicle propulsion driven by n-phase (n is a natural number greater than or equal to 3) alternating current, An inverter that drives the motor, An inverter abnormality determination unit for determining an abnormality in the inverter, When the inverter abnormality determination unit determines that the inverter is abnormal, the drive system abnormality determination unit determines that the drive system including the motor and the inverter is abnormal if the rate of temperature change of at least one of the cables supplying power to each phase of the motor exceeds a threshold, Equipped with, The drive system abnormality determination unit determines that at least one of the temperature sensors installed on each of the cables is malfunctioning, and sets the threshold value to a smaller value than when it is determined that there is no malfunction.

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