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 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.

Description

Technical Field

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

Background Art

[0002] As a vehicle control device for driving a vehicle, there has been proposed one that includes a three-phase motor and an inverter for driving the three-phase motor, and detects an open-failed switching element 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 failure of any of the switching elements is detected, by continuing vector control with the synthetic voltage vector fixed, it is possible to generate some torque in almost all regions from the three-phase motor. 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 when the fuse blows due to an excessive current based on a short-circuit failure or malfunction of the switching element of the inverter, a three-phase short circuit is caused (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]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] 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. [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 processing as an inverter abnormality determination unit that determines an abnormality in the inverter 132. Specifically, in step S101, the electronic control unit 150 inputs the voltage phase command φ*, and in the subsequent step S102, it checks whether the voltage phase command φ* is equal to either of the phase limiters φmin, 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 and the absolute value of the deviation ΔTrg becomes large, so that the target voltage phase φtmp exceeds the phase limiters φmin, φmax by the above feedback control, and thus the voltage phase command φ* is limited by the phase limiters φmin, φmax. Therefore, it is possible to determine whether an abnormality may have occurred in the inverter 132 by checking whether the voltage phase command φ* is equal to either of the phase limiters φmin, φmax.

[0020] When the voltage phase command φ* is not equal to either of the phase limiters φmin, 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 of the phase limiters φmin, 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 the threshold Cref for inverter abnormality determination. If the abnormality counter C does not exceed the threshold Cref, the processing from step S101 to step S105 is 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 and, when it determines that an abnormality has occurred in the inverter 132, 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 travel control for retreat travel from normal travel 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, 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, Tw are continuously input after a certain period of time.

[0023] The electronic control unit 150 proceeds to step S108 and calculates the temperature change rates ΔTu, ΔTv, ΔTw, which are the change temperatures per unit time, from the cable temperatures Tu, Tv, Tw acquired this time and the cable temperatures Tu, Tv, Tw acquired last time. Then, each of the calculated temperature change rates ΔTu, ΔTv, ΔTw is compared with the threshold value ΔTref for drive system abnormality determination, and it is confirmed whether any one of them exceeds the threshold value ΔTref.

[0024] Here, the threshold value ΔTref is a threshold value of the temperature change rate of the cable used to determine an abnormality in the drive system including the motor 130 and the inverter 132 before irreversible demagnetization of the magnet of the motor 130 occurs, and is determined based on the temperature change rate assumed to reach the temperature at which irreversible demagnetization of the motor 130 occurs. The threshold value ΔTref varies depending on the specifications of the motor 130 and the characteristics of the connected cables, and is determined, for example, by prior trial and error.

[0025] If the electronic control unit 150 confirms in step S108 that none of ΔTu, ΔTv, or ΔTw exceed the threshold ΔTref, it returns to step S107 and repeats steps S107 and S108 at regular intervals. If it confirms that at least one of ΔTu, ΔTv, or ΔTw exceeds the threshold ΔTref, it proceeds to step S109, 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, it is possible to protect the motor coil of the motor 130 while ensuring a longer travel distance during the retraction run.

[0026] 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.

[0027] 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]

[0028] 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. A vehicle control device equipped with the following features.

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