Electric vehicle

Abstract

When a motor is driven by a first inverter and a second inverter with a change-over switch in an ON state, a first exceeding phase is present in which the difference between the detection values of a first current sensor and a second current sensor is greater than a first threshold value among phases, and a second exceeding phase is present in which the difference between the detection values of the first current sensor and the second current sensor is greater than the first threshold value. And a control unit that determines that any one of the first current sensor and the second current sensor of each phase is abnormal, turns the change-over switch into an off state, and controls the first inverter and the second inverter such that a current based on a counter electromotive force accompanying rotation of the motor flows through circuits of the first inverter, the motor, and the second inverter. Then, an abnormal current sensor among the first current sensor and the second current sensor of each phase is identified.

Description

Technical Field

[0001] This disclosure relates to a vehicle. Background Technology

[0002] Conventional electric vehicles include an energy storage device, a motor with a three-phase open winding for driving, and a first inverter connected to one end of the three-phase open winding. The first inverter is also connected to a power line. The aforementioned conventional electric vehicles further include: a second inverter connected to the other end of the three-phase open winding; and a switching switch disposed between the first and second inverters on the positive side of the power line. The second inverter is also connected to the side of the power line opposite to the first inverter and the energy storage device (for example, see Japanese Patent Application Laid-Open No. 2022-21849). In this selected vehicle, a current sensor is installed on each phase of the three-phase open winding. Furthermore, in this electric vehicle, when the switching switch is turned on to drive the motor via the first and second inverters (H-drive), anomaly diagnosis of the current sensors for each phase is performed based on the sum of the phase currents of each phase.

[0003] In such electric vehicles, it is required to be able to identify the faulty current sensor if any one of the current sensors in each phase malfunctions. During H-drive, there are cases where the sum of the phase currents is not zero, which may prevent the identification of the faulty current sensor. Summary of the Invention

[0004] The main objective of the electric vehicle disclosed herein is to identify the current sensor that caused the malfunction when any one of the current sensors in each phase malfunctions.

[0005] To achieve the aforementioned main objectives, the electric vehicle disclosed herein employs the following mechanism.

[0006] The electric vehicle disclosed herein includes: an energy storage device; a driving motor having a three-phase open winding; a first inverter connected to a power line and to one end of the three-phase open winding; a second inverter connected to the side of the power line opposite to the first inverter and the energy storage device, and to the other end of the three-phase open winding; a switching switch disposed between the first inverter and the second inverter on the positive side of the power line; and a control device for controlling the first inverter, the second inverter, and the switching switch. Its main purpose is...

[0007] The electric vehicle is equipped with a first current sensor and a second current sensor for each phase of the three-phase open winding. When the control device turns the switch on to drive the motor via the first inverter and the second inverter, if there is a first over-limit phase where the difference between the detected values ​​of the first current sensor and the second current sensor is greater than a first threshold, the control device determines that any one of the first current sensor and the second current sensor for that phase is abnormal, and turns the switch off. The control device then adjusts the switching device based on the aforementioned... The current of the back electromotive force of the rotating motor flows in the circuits of the first inverter, the motor, and the second inverter to control the first inverter and the second inverter. An abnormal current sensor among the first and second current sensors of each phase is determined based on the larger of the absolute values ​​of either the second exceeding phase (where the difference between the detection values ​​of the first and second current sensors in each phase is greater than a second threshold) or the sum of the detection values ​​of the first current sensors in the first exceeding phase and the sum of the detection values ​​of the second current sensors in each phase.

[0008] The aforementioned control device controls the first inverter and the second inverter in a manner that avoids collisions without using the aforementioned abnormal current sensor.

[0009] In the electric vehicle disclosed herein, when the control device turns on the switch to drive the motor via the first inverter and the second inverter, if there is a first over-current phase in which the difference between the detection values ​​of the first current sensor and the second current sensor in each phase is greater than a first threshold, it determines that any one of the first current sensor or the second current sensor in each phase is abnormal, turns on the switch to the off state, and controls the first inverter and the second inverter to control the circuit formed by the first inverter, the motor, and the second inverter by allowing current based on the back electromotive force accompanying the rotation of the motor to flow through it. Furthermore, the control device determines the abnormal current sensor in each phase based on either the second over-current phase in which the difference between the detection values ​​of the first current sensor and the second current sensor in each phase is greater than a second threshold, or the absolute value of the first over-current phase, the sum of the detection values ​​of the first current sensor in each phase, and the sum of the detection values ​​of the second current sensor in each phase, whichever is greater. The control device then controls the first inverter and the second inverter to perform reverse driving without using the abnormal current sensor. Therefore, if any one of the current sensors in each phase malfunctions, the malfunctioning current sensor can be identified.

[0010] In the vehicle disclosed herein, the control device may, when determining that any one of the first current sensor or the second current sensor of each phase is abnormal and causing the switching switch to be in the open state, turn the upper arm of the first inverter and the lower arm of the second inverter to be in the on state and turn the lower arm to be in the off state.

[0011] In the electric vehicle disclosed herein, if the aforementioned abnormal current sensor is detected, the control device can control the first inverter and the second inverter by keeping the switching switch in the open state, neutralizing the other end of the three-phase open winding, and driving the motor through the switch of the first inverter, thereby enabling the electric vehicle to perform reverse driving. This allows reverse driving to be performed while keeping the switching switch in the open state. Here, neutralizing the other end of the three-phase open winding can be achieved by turning on the upper arm of the second inverter and turning off the lower arm. Attached Figure Description

[0012] Hereinafter, the features, advantages, technical and industrial importance of exemplary embodiments of the present invention will be described with reference to the accompanying drawings, in which the same reference numerals denote the same constituent elements, wherein:

[0013] Figure 1 This is a schematic diagram of a battery-powered electric vehicle according to an embodiment of the present invention.

[0014] Figure 2 This is a flowchart representing an example of a processing routine executed by the ECU.

[0015] Figure 3 This is an explanatory diagram showing the situation when a specific process is executed.

[0016] Figure 4 This is a schematic diagram of a modified battery-powered electric vehicle. Detailed Implementation

[0017] The embodiments (implementations) for carrying out this disclosure will be described with reference to the accompanying drawings. Figure 1 This is a schematic configuration diagram of a battery-electric vehicle 10 according to an embodiment of the present disclosure. As shown, the battery-electric vehicle 10 of the embodiment includes a battery 12 as an energy storage device, a motor 20, a first inverter 22, and a second inverter 24. Additionally, as shown, the battery-electric vehicle 10 of the embodiment includes a capacitor 30, a switching switch 34p, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0018] The storage battery 12 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the power lines 16 (positive side line 16p and negative side line 16n). The motor 20 is configured as a three-phase AC motor, having a rotor with permanent magnets embedded in the rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils (three-phase open winding) wound in the stator core. The rotor is connected to a drive shaft via a differential gear to a drive wheel.

[0019] The first inverter 22 and the second inverter 24 each include six transistors T11-T16 and T21-T26 as six switching elements. Additionally, each of the first inverter 22 and the second inverter 24 includes six diodes D11-D16 and D21-D26 connected in parallel with the six transistors T11-T16 and T21-T26. Transistors T11-T16 and T21-T26 may be MOSFETs or IGBTs, for example. Transistors T11-T16 and T21-T26 are arranged in pairs, with the positive terminal line 16p and the negative terminal line 16n serving as the source and sink sides, respectively. The connection points of the pairs of transistors T11-T16 are each connected to one end of the three-phase coil of the motor 20. The connection points of the pairs of transistors T21-T26 are each connected to the other end of the three-phase coil of the motor 20. Hereinafter, transistors T11~T13 are sometimes referred to as the "first upper arm", transistors T14~T16 as the "first lower arm", transistors T21~T23 as the "second upper arm", and transistors T24~T26 as the "second lower arm".

[0020] Capacitor 30 is connected near the first inverter 22 on power line 16. In this embodiment, on power line 16 from... Figure 1 Starting from the left side, the battery 12, capacitor 30, first inverter 22, and second inverter 24 are connected in sequence. A switching switch 34p is located between the first inverter 22 and the second inverter 24 in the positive terminal line 16p. The switching switch 34p can be, for example, a semiconductor switch or an insulated switch.

[0021] ECU 50 is equipped with a microcomputer featuring a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and logic ICs. Signals from various sensors are input to ECU 50. For example, the voltage Vb of battery 12 from voltage sensor 12V, the current Ib of battery 12 from current sensor 12i, and the temperature Tb of battery 12 from temperature sensor 12t are input to ECU 50. ECU 50 also receives the rotational position θm of motor 20's rotor from rotational position sensor 20a, and the phase currents Iua and Iub of motor 20's U-phase from the first current sensor 20ua and the second current sensor 20ub mounted on motor 20. Additionally, ECU 50 receives the phase currents Iva and Ivb of motor 20's V-phase from the first current sensor 20va and the second current sensor 20vb mounted on motor 20. In addition, the ECU 50 is also input with the phase currents Iwa and Iwb of the W phase of the motor 20 from the first current sensor 20wa and the second current sensor 20wb installed on the W phase of the motor 20. Thus, current sensors are installed in a dual-system configuration for each phase of the motor 20. Regarding each phase, the first current sensors 20ua, 20va, and 20wa are "first-channel current sensors," and the second current sensors 20ub, 20vb, and 20wb are "second-channel current sensors." For example, the first-channel current sensors are used for current detection, and the second-channel current sensors are used for anomaly detection (monitoring of the first channel) as described later. The ECU 50 is also input with the voltage VH from the capacitor 30 of the voltage sensor 30v. The ECU 50 is also input with the on / off signal from the power switch 60 and the operating position (gear SP) of the shift lever 61 from the gear position sensor 62. Additionally, the ECU 50 is also input with the amount of pressure applied to the accelerator pedal 63 (accelerator opening Acc) from the accelerator pedal position sensor 64, and the amount of pressure applied to the brake pedal 65 (brake pedal position BP) from the brake pedal position sensor 66. Furthermore, the ECU 50 is also input with the vehicle speed V from the vehicle speed sensor 67.

[0022] Various control signals are output from ECU 50. For example, control signals are output from ECU 50 for transistors T11~T16 of the first inverter 22, transistors T21~T26 of the second inverter 24, and the switching switch 34p. ECU 50 calculates the state of charge (SOC) of battery 12 based on the accumulated value of current Ib of battery 12, or calculates the electrical angle θe and rotational speed Nm of motor 20 based on the rotational position θm of the rotor of motor 20.

[0023] In the battery-electric vehicle 10 of the embodiment, the ECU 50 controls the switch 34, the first inverter 22, and the second inverter 24 in basically as follows: The required torque Td* for driving is set based on the accelerator opening Acc and the vehicle speed V, and the torque command Tm* of the motor 20 is set in such a way that driving is achieved by the set required torque Td*. Then, with the switch 34p in the on state, the transistors T11~T16 and T21~T26 of the first inverter 22 and the second inverter 24 are switched on and off to drive the motor 20 with the torque command Tm*. Hereinafter, such control of the switch 34 and the first inverter 22 and the second inverter 24 will be referred to as "H-drive".

[0024] The first inverter 22 and the second inverter 28 are controlled using torque command Tm*, electrical angle θe, and phase currents Iu, Iv, and Iw of each phase via pulse width modulation (PWM) control and rectangular wave control. The phase current Iu of phase U is a representative value of the phase currents Iua and Iub of phase U of motor 20 from the first current sensor 20ua and the second current sensor 20ub, for example, using phase current Iua. The phase currents Iv and Iw of phases V and W are controlled similarly.

[0025] Next, the operation of the battery-electric vehicle 10 according to the embodiment will be explained. Figure 2 This is a flowchart illustrating an example of a processing routine executed by ECU50. This routine is repeatedly executed during H-drive operation, provided that no abnormality is detected in any of the first current sensors 20ua, 20va, 20wa, or the second current sensors 20ub, 20vb, 20wb for the U, V, and W phases.

[0026] If this routine is executed, ECU50 determines whether all the first current sensors 20ua, 20va, 20wa, and the second current sensors 20ub, 20vb, and 20wb of phases U, V, and W are normal or any one is abnormal (S100). In this determination process, for phase U, if the difference ΔIu (the absolute value of the difference between one and the other) of the phase currents Iua and Iub from the first current sensor 20ua and the second current sensor 20ub is below the threshold ΔIuref, then both the first current sensor 20ua and the second current sensor 20ub of phase U are determined to be normal. In this determination process, if the difference ΔIu exceeds the threshold ΔIuref, then any one of the first current sensors 20ua and the second current sensor 20ub of phase U is determined to be abnormal. In this determination process, for phase V, if the difference ΔIv between the phase currents Iva and Ivb from the first current sensor 20va and the second current sensor 20vb is below the threshold ΔIvref, both the first current sensor 20va and the second current sensor 20vb in phase V are determined to be normal. If the difference ΔIv exceeds the threshold ΔIvref, either the first current sensor 20va or the second current sensor 20vb in phase V is determined to be abnormal. Similarly, for phase W, if the difference ΔIw between the phase currents Iwa and Iwb from the first current sensor 20wa and the second current sensor 20wb is below the threshold ΔIwref, both the first current sensor 20wa and the second current sensor 20wb in phase W are determined to be normal. If the difference ΔIw exceeds the threshold ΔIwref, either the first current sensor 20wa or the second current sensor 20wb in phase W is determined to be abnormal. The thresholds ΔIuref, ΔIvref, and ΔIwref are determined based on the specifications (detection error) of the first current sensor 20ua and the second current sensor 20ub in phase U, respectively. Additionally, the thresholds ΔIuref, ΔIvref, and ΔIwref are also determined based on the specifications of the first current sensor 20va and the second current sensor 20vb in phase V, and the specifications of the first current sensor 20wa and the second current sensor 20wb in phase W, respectively. The thresholds ΔIuref, ΔIvref, and ΔIwref can all be the same value, or at least one can be different.

[0027] When S100 determines that the first current sensors 20ua, 20va, and 20wa of phase U, phase V, and phase W, and the second current sensors 20ub, 20vb, and 20wb are all normal, this routine ends.

[0028] When S100 determines that any one of the first current sensors 20ua, 20va, and 20wa of the U-phase, V-phase, and W-phase, or the second current sensors 20ub, 20vb, and 20wb, is abnormal, a determination process (S110) for identifying the abnormal current sensor is executed. Here, in the determination process, the process of switching the changeover switch 34p from the ON state to the OFF state is executed. Additionally, in the determination process, the process of setting the first upper arm (transistors T11-T13) and the second upper arm (transistors T21-T23) of the first inverter 22 and the second inverter 24 to the ON state is executed. Simultaneously, in the determination process, the process of setting the first lower arm (transistors T14-T16) and the second lower arm (transistors T24-T26) to the OFF state is executed. Figure 3 This is an explanatory diagram illustrating the situation at this time. If the determination process is performed while the motor 20 is rotating at a certain speed, then... Figure 3 As shown by the thick solid lines, a circuit is formed based on the first upper arm, motor 20, and second upper arm. Current flows (circulates) in this circuit based on the back electromotive force accompanying the rotation of motor 20. In this case, the sum of the actual currents in the U-phase, V-phase, and W-phase of motor 20 is 0.

[0029] Next, abnormal phase determination processing and abnormal channel determination processing (S120) are performed to determine the phase (abnormal phase) and channel (abnormal channel) of the abnormal current sensor. The processing of S120 targets the first current sensor 20ua, 20va, 20wa and the second current sensor 20ub, 20vb, 20wb of the U phase, V phase and W phase.

[0030] Here, in the abnormal phase determination process, the abnormal phase is determined by performing the same process as the determination process in S100. In the abnormal channel determination process, the sum It1 of the phase currents Iua, Iva, and Iwa from the current sensors (first current sensors 20ua, 20va, and 20wa) of the first channel is calculated. At the same time, in the abnormal channel determination process, the sum It2 of the phase currents Iub, Ivb, and Iwb from the current sensors (second current sensors 20ub, 20vb, and 20wb) of the second channel is calculated. If the absolute value of the sum It1 is greater than the absolute value of the sum It2, the first channel is determined to be an abnormal channel. If the absolute value of the sum It1 is less than the absolute value of the sum It2, the second channel is determined to be an abnormal channel. As mentioned above, the sum of the actual currents of the U-phase, V-phase, and W-phase of the motor 20 is 0, therefore the channel corresponding to the one with the larger absolute value of the sums It1 and It2 is determined to be an abnormal channel.

[0031] If the abnormal phase and abnormal channel are determined in this way, an abnormal current sensor is determined based on the determined abnormal phase and abnormal channel (S130). For example, if the abnormal phase is phase U and the abnormal channel is the first channel, the first current sensor 20ua of phase U is determined as the abnormal current sensor. Then, for the abnormal phase, a current sensor other than the abnormal current sensor is set as the current sensor for current detection (S140). For example, if the abnormal current sensor is the first current sensor 20ua of phase U, the second current sensor 20ub is used as the current sensor for detection for phase U.

[0032] Next, the process transitions to Y-drive reversing (S150), ending this routine. During Y-drive reversing, the switch 34p remains in the off state, and the side of the motor 20 closest to the second inverter 24 (the other end of the three-phase coils of the motor 20) is neutralized. Furthermore, during Y-drive reversing, the motor 20 is driven by the switching of the first inverter 22 (transistors T11-T16). Neutralization of the side of the motor 20 closest to the second inverter 24 is achieved by setting the second upper arm (transistors T21-T23) of the second inverter 24 to the on state and setting the second lower arm (transistors T24-T26) to the off state. This allows reversing to occur without switching the state of the switch 34p from off to on.

[0033] In the battery-electric vehicle 10 described above, during H-drive operation, it is sometimes determined that any one of the first current sensors 20ua, 20va, 20wa, and the second current sensors 20ub, 20vb, 20wb for the U-phase, V-phase, and W-phase is abnormal. In this case, as a determination process, the switch 34p is set to the off state, and the first upper arm and the second upper arm are set to the on state while the first lower arm and the second lower arm are set to the off state. As a result, a current based on the back electromotive force accompanying the rotation of the motor 20 flows in the circuits of the first upper arm of the first inverter 22, the motor 20, and the second upper arm of the second inverter 24. Then, the abnormal phase and abnormal channel are determined by the abnormal phase determination process and the abnormal channel determination process, thereby determining the abnormal current sensor. In this way, the abnormal current sensor can be determined.

[0034] Furthermore, in the battery-electric vehicle 10 of the embodiment, if an abnormal current sensor is detected, a current sensor other than the abnormal current sensor is set as the detection current sensor for the abnormal phase, and the process is switched to reverse driving in Y-drive mode. This allows reverse driving to be performed while keeping the switch 34p in the open state.

[0035] In the above embodiments, in Figure 2In the processing routine, in S100, it is determined whether all the first current sensors 20ua, 20va, and 20wa, and the second current sensors 20ub, 20vb, and 20wb of phases U, V, and W are normal or any one is abnormal. Furthermore, in S120, abnormal phase determination processing and abnormal channel determination processing are performed. However, the processing routine is not limited to this. For example, in S100, if any one of the first current sensors 20ua, 20va, and 20wa, and the second current sensors 20ub, 20vb, and 20wb of phases U, V, and W is determined to be abnormal, an abnormal phase can also be determined. For example, phase U can be determined as an abnormal phase if the difference ΔIu exceeds the threshold ΔIuref.

[0036] In the above implementation, if an abnormal current sensor is detected, the system switches to reverse driving via Y-drive, but is not limited to this. For example, it is also possible to wait for the vehicle to stop, switch 34p from the off state to the on state, and then reverse driving via H-drive.

[0037] In the above embodiments, such as Figure 1 It can be configured like a battery-powered electric vehicle 10, but is not limited to that. For example, such as Figure 4 As shown in the modified example of the battery-powered electric vehicle 110, the electric vehicle of this disclosure, in addition to having the same features as... Figure 1 In addition to the same hardware structure as the battery-electric vehicle 10, it may also include a capacitor 32 and a switching switch 34n. The capacitor 32 is connected near the second inverter 24 in the power line 16. The voltage VL from the voltage sensor 32V, which detects the voltage VL of the capacitor 32, is input to the ECU 50. The switching switch 34n is located between the first inverter 22 and the second inverter 24 in the negative side line 16n and is controlled by the ECU 50. In this battery-electric vehicle 110, in a specific process, the switching switches 34p and 34n can be switched from the on state to the off state. In addition, during Y-drive reverse driving, the switching switches 34p and 34n can be kept in the off state.

[0038] In the above embodiments, the vehicles are described as battery electric vehicles 10 and 110, but are not limited to this. For example, the vehicle of this disclosure may also be a hybrid electric vehicle that has the same hardware structure as battery electric vehicles 10 and 110 but also has an engine. Alternatively, the electric vehicle of this disclosure may also be a fuel cell electric vehicle that has the same hardware structure as battery electric vehicles 10 and battery 110 but also has a fuel cell.

[0039] The correspondence between the main elements of the implementation method and the main elements of the invention as described in the Summary of the Invention section will be explained. In the implementation method, the battery 12 corresponds to an "energy storage device", the motor 20 corresponds to a "motor", the first inverter 22 corresponds to a "first inverter", and the second inverter 24 corresponds to a "second inverter". In addition, the switch 34p corresponds to a "switch", and the ECU 50 corresponds to a "control device".

[0040] Furthermore, the correspondence between the main elements of the implementation method and the main elements of the invention described in the description of the invention is merely an example used to specifically illustrate how the implementation method is used to carry out the invention described in the description of the invention. Therefore, this correspondence does not limit the elements of the invention described in the description of the invention. That is, the interpretation of the invention described in the description of the invention should be based on the description in that section, and the implementation method is merely a specific example of the invention described in the description of the invention.

[0041] The above describes the methods for implementing this disclosure using the embodiments, but this disclosure is not limited to such embodiments. Of course, it can be implemented in various ways without departing from the spirit of this disclosure.

[0042] This disclosure can be applied to industries such as electric vehicle manufacturing.

Claims

1. An electric vehicle comprising: an energy storage device; a driving motor having a three-phase open winding; a first inverter connected to a power line and to one end of the three-phase open winding; a second inverter connected to the side of the power line opposite to the first inverter and the energy storage device and to the other end of the three-phase open winding; a switching switch disposed between the first inverter and the second inverter on the positive side of the power line; and a control device for controlling the first inverter, the second inverter, and the switching switch, wherein... The electric vehicle is equipped with a first current sensor and a second current sensor respectively installed on each phase of the three-phase open winding. When the control device turns the switching switch on to drive the motor via the first inverter and the second inverter, if there is a first phase in which the difference between the detection values ​​of the first current sensor and the second current sensor in each phase is greater than a first threshold, it determines that any one of the first current sensor and the second current sensor in each phase is abnormal, and turns the switching switch off. The control device then controls the first inverter and the second inverter in a manner that the current flowing through the circuit formed by the first inverter, the motor, and the second inverter is based on the back electromotive force accompanying the rotation of the motor. The control device determines the abnormal current sensor among the first current sensors and second current sensors of each phase based on the larger of the absolute value of either the second exceeding phase where the difference between the detection values ​​of the first current sensor and the second current sensor in each phase is greater than a second threshold, or the first exceeding phase, the sum of the detection values ​​of the first current sensor in each phase, and the sum of the detection values ​​of the second current sensor in each phase. The control device controls the first inverter and the second inverter in a reverse driving manner without using the abnormal current sensor.

2. The electric vehicle according to claim 1, wherein, When the control device determines that any one of the first current sensor or the second current sensor of each phase is abnormal and causes the switching switch to be in the open state, it turns the upper arm of the first inverter and the lower arm of the second inverter into the on state and turns the lower arm into the off state.

3. The electric vehicle according to claim 1 or 2, wherein, If the abnormal current sensor is detected, the control device keeps the switching switch in the off state to neutralize the other end of the three-phase open winding and control the first inverter and the second inverter in a manner that drives the motor through the switch of the first inverter, thereby enabling the electric vehicle to reverse.

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