electric vehicles

Abstract

To determine a conduction failure of a cut-off circuit without adding an additional configuration.SOLUTION: A bypass relay is turned off and a neutral point relay is turned on to connect a DC charger to a neutral point of a three-phase AC motor and a negative electrode-side line of a power line, When the voltage of external DC power is risen to start charging a battery, an inverter is controlled to adjust the voltage of a capacitor to be a first predetermined voltage in a state where a system main relay and the neutral relay are turned on and a neutral point-side cut-off circuit and a negative electrode-side cut-off circuit are turned off (cut off). When a voltage sensor detects a rise in voltage at that time, it is determined that a conduction failure occurs in the negative electrode-side cut-off circuit.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to an electric vehicle, and more particularly to an electric vehicle including a battery, a three-phase AC motor, and a DC charger that charges the battery using external DC power. [Background technology]

[0002] Conventionally, one proposed electric vehicle of this type includes a battery, a three-phase AC motor, an inverter connected to the battery by a power line and using power from the battery to drive the three-phase AC motor, and a charger connected to the neutral point of the three-phase AC motor via a relay and using external power to charge the battery (see, for example, Patent Document 1).In this electric vehicle, the charger is equipped with a leakage detection circuit that detects leakage and a breaker that cuts off when a leakage is detected, as well as a leakage breaker that has a leakage test relay and a leakage resistor, and when charging, the leakage test relay is closed to forcibly short-circuit the circuit, and it is confirmed whether the breaker relay functions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-205909 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the electric vehicle described above, the earth leakage breaker needs to be equipped with an additional earth leakage test relay and earth leakage resistor in order to determine whether the cut-off relay has failed, which makes the configuration complicated and increases the size of the earth leakage breaker.

[0005] The electric vehicle of the present disclosure has a primary objective of determining a continuity fault in the interrupter circuit without adding any additional configuration. [Means for solving the problem]

[0006] The electric vehicle of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The electric vehicle disclosed herein is An electric vehicle including: a battery; a three-phase AC motor; an inverter that drives the three-phase AC motor using power from the battery; a system main relay with a pre-charge function that is provided in a power line that connects the battery and the inverter; a DC charger that charges the battery using external DC power supplied from an external charging connector; and a control device, The DC charger includes a charging power line connected between the external charging connector and the inverter on the power line, a bypass relay attached to a positive side line of the charging power line, a neutral point charging line connecting a neutral point of the three-phase AC motor to the external charging connector on the positive side line of the charging power line and the bypass relay, a neutral point relay attached to the neutral point charging line, and a power line connected from the neutral point relay on the neutral point charging line to the external charging connector. a neutral point side interrupting circuit connected to the external charging connector side of the charging power line, a negative side interrupting circuit attached to the negative side line of the charging power line, a capacitor connected to the power line side of the negative side line of the charging power line from the negative side interrupting circuit and between the neutral point relay and the neutral point side interrupting circuit of the neutral point charging line, and a voltage sensor connected to the external charging connector side of the neutral point side interrupting circuit of the neutral point charging line and to the external charging connector side of the negative side line of the charging power line, the control device determines that a continuity fault has occurred in the negative side shutoff circuit when a voltage rise is detected by the voltage sensor while the inverter is controlled so that the voltage of the capacitor becomes a first predetermined voltage with the system main relay and the neutral point relay turned on and the neutral point side shutoff circuit and the negative side shutoff circuit turned off (shut off), It is characterized by:

[0008] In the electric vehicle disclosed herein, the inverter is controlled to maintain the capacitor voltage at a first predetermined voltage while the system main relay and neutral point relay are turned on and the neutral point side shutoff circuit and negative point side shutoff circuit are turned off (shut off). When a voltage rise is detected by voltage sensors connected to the neutral point charging line on the external charging connector side of the neutral point side shutoff circuit and the negative side line of the charging power line on the external charging connector side of the negative point side shutoff circuit, it is determined that a continuity fault has occurred in the negative point side shutoff circuit. This is based on the fact that the voltage detected by the voltage sensor does not change when there is no continuity fault in the negative point side shutoff circuit. As a result, a continuity fault in the negative point side shutoff circuit can be determined without the need for additional configuration.

[0009] In the electric vehicle disclosed herein, the control device may be configured to turn on the neutral point side interrupting circuit (release interruption) when it determines that no continuity fault has occurred in the negative pole side interrupting circuit, and to determine that a continuity fault has occurred in the neutral point side interrupting circuit when the voltage sensor detects a voltage drop after controlling the inverter so that the capacitor voltage becomes the first predetermined voltage and then controlling the inverter so that the capacitor voltage becomes a second predetermined voltage that is lower than the first predetermined voltage. This is based on the fact that when no continuity fault has occurred in the neutral point side interrupting circuit, the voltage detected by the voltage sensor does not change. As a result, it is possible to determine that a continuity fault has occurred in the neutral point side interrupting circuit without providing any additional configuration.

[0010] In the electric vehicle of the present disclosure, the control device may prohibit charging of the battery using the external DC power when it determines that a continuity fault has occurred in the negative pole side breaking circuit and / or the neutral point side breaking circuit. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an outline of the configuration of an electric vehicle 20 according to an embodiment of the present disclosure. [Figure 2]4 is a flowchart showing an example of a boost charging start process executed by an electronic control unit 60. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of an electric vehicle 20 according to an embodiment of the present disclosure. The electric vehicle 20 of the embodiment includes a motor 22 for driving, an inverter 24 that drives the motor 22, a battery 26, a charger 40, and an electronic control unit 60.

[0013] The motor 22 is configured as a well-known synchronous generator-motor, for example, including a rotor with a permanent magnet attached to its outer surface and a stator around which a three-phase coil is wound. The inverter 24 is configured with six transistors T1-T6 and six diodes D1-D6 connected in parallel in the opposite directions to the transistors T1-T6. The transistors T1-T6 are arranged in pairs, two on the source side and two on the sink side of the positive and negative buses that the inverter 24 shares as a power line 30. Each of the three-phase coils (U-phase, V-phase, and W-phase) of the motor 22 is connected to each of the junctions between the paired transistors. Therefore, by controlling the proportion of the on-time of the paired transistors T1-T6 when a voltage is applied between the positive and negative buses, a rotating magnetic field can be generated in the three-phase coils, thereby driving the motor 22 to rotate. A smoothing capacitor 34 is connected to the power line 30.

[0014] Battery 26 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to power line 30. A system main relay 28 is attached to power line 30. System main relay 28 has a positive relay SMRB provided on the positive line of power line 30, a negative relay SMRG provided on the negative line of power line 30, and a precharge circuit in which a precharge resistor R and a precharge relay SMRP are connected in series to bypass the negative relay SMRG. A filter 32 that removes noise is also attached to power line 30.

[0015] The charger 40 includes an external charging connector 42 that connects to an external power source, a charging power line 43 (positive side line 44 and negative side line 45) that is connected to the external charging connector 42 and is connected between the system main relay 28 and the inverter 24 of the power line 30 (between the filter 32 and the inverter 24 in FIG. 1 ), and a neutral point charging line 50 that is connected to the positive side line 44 of the charging power line 43 and the neutral point of the motor 22.

[0016] A charging relay 48 and a noise filter 49 including a smoothing capacitor are attached to the charging power line 43, in this order from the external charging connector 42 side. The charging relay 48 has a positive relay CHRB provided on a positive line 44 of the charging power line 43 and a negative relay CHRG provided on a negative line 45 of the charging power line 43. A bypass relay 46 is attached to the positive line 44 of the charging power line 43. A negative cutoff circuit 47 is attached to the negative line 45 of the charging power line 43. The negative cutoff circuit 47 is configured to connect in parallel a diode whose forward direction is from the battery 26 to the external charging connector 42, a transistor as a switching element, and a varistor.

[0017] A neutral point relay 51 and a neutral point side shutoff circuit 52 are attached to the neutral point charging line 50, in this order from the motor 22 side. Similar to the negative side shutoff circuit 47, the neutral point side shutoff circuit 52 is configured by connecting in parallel a diode whose forward direction is from the battery 26 to the external charging connector 42, a transistor as a switching element, and a varistor.

[0018] Terminals of a capacitor 53 are connected between the neutral point relay 51 and the neutral point side interrupting circuit 52 of the neutral point charging line 50, and to the battery 26 side of the negative side interrupting circuit 47 of the negative side line 45 of the charging power line 43. A voltage sensor 54 that detects the voltage between the neutral point charging line 50 and the negative side line 45 is connected to the external charging connector 42 side of the neutral point side interrupting circuit 52 of the neutral point charging line 50, and to the external charging connector 42 side of the negative side interrupting circuit 47 of the negative side line 45 of the charging power line 43. A leakage detection circuit 55 that detects leakage current is also attached to the neutral point charging line 50 and the negative side line 45.

[0019] Although not shown, the electronic control unit 60 is configured as a microprocessor centered on a CPU. In addition to the CPU, the electronic control unit 60 includes a ROM for storing processing programs, a RAM for temporarily storing data, a flash memory, input / output ports, and communication ports. Signals from various sensors are input to the electronic control unit 60 via the input ports. Examples of signals input to the electronic control unit 60 include the rotational position θm from a rotational position detection sensor (e.g., a resolver) 23 that detects the rotational position of the rotor of the motor 22, phase currents flowing through the three-phase coils (U-phase, V-phase, and W-phase) of the motor 22, a voltage VL from a voltage sensor 54 provided in the charger 40, and a detection signal from a leakage detection circuit 55. The electronic control unit 60 is also connected to a communication line for communicating with an external DC power supply via the external charging connector 42. The electronic control unit 60 also functions as a control device for the electric vehicle 20, and therefore also receives inputs such as a shift position, accelerator position, and brake position.

[0020] Various control signals are output via output ports from the electronic control unit 60. Examples of signals output from the electronic control unit 60 include a switching control signal to the transistors T1 to T6 of the inverter 24, a drive control signal to the system main relay 28, a drive control signal to the charging relay 48, a drive control signal to the bypass relay 46, a drive control signal to the neutral point relay 51, a drive control signal to the negative pole side shutoff circuit 47, and a drive control signal to the neutral point side shutoff circuit 52.

[0021] When an external DC power supply is connected to the external charging connector 42 of the charger 40, the electronic control unit 60 inputs the voltage Vd of DC power supplied by the external DC power supply (external DC voltage Vd), and when the external DC voltage Vd is higher than the voltage Vb of the battery 26, the electronic control unit 60 charges the battery 26 by normal charging using the charger 40. When the external DC voltage Vd is lower than the voltage Vb of the battery 26, the electronic control unit 60 charges the battery 26 by boost charging using the charger 40. In normal charging, the bypass relay 46 is turned on, the neutral point relay 51 is turned off, and the system main relay 28 is turned on, and the battery 26 is charged using the positive line 44 and negative line 45 of the charging power line 43. In boost charging, the bypass relay 46 is turned off, the neutral point relay 51 is turned on, and the system main relay 28 is turned on, and the battery 26 is charged using the neutral point charging line 50 and the negative line 45 of the charging power line 43. In this boost charging, the combination of the three-phase coils (U phase, V phase, W phase) of the motor 22 and each phase of the inverter 24 functions as a boost circuit by switching the transistors T1 to T6 of the inverter 24, thereby boosting the voltage of the external DC power and charging the battery 26.

[0022] Next, a description will be given of the operation of the electric vehicle 20 configured as described above, in particular the operation when starting boost charging by the charger 40. FIG.

[0023] When the boost charging start process is executed, the electronic control unit 60 first turns on the system main relay 28 (step S100) and the neutral relay 51 (step S110) while both the neutral point side shutoff circuit 52 and the negative pole side shutoff circuit 47 are off (shut down). Then, the electronic control unit 60 controls the switching of the transistors T1 to T6 of the inverter 24 to cause each phase of the motor 22 and each phase of the inverter 24 to function as a boost circuit, thereby charging the capacitor 53 until the voltage of the capacitor 53 reaches a first predetermined voltage (e.g., 400 V) (step S120). Then, the electronic control unit 60 determines whether the sensor voltage of the voltage sensor 54 is increasing (step S130). Because both the neutral point side shutoff circuit 52 and the negative pole side shutoff circuit 47 are off (shut down), the sensor voltage does not increase when the negative pole side shutoff circuit 47 is normal, but the sensor voltage increases when a continuity fault occurs in the negative pole side shutoff circuit 47. Therefore, if it is determined that the sensor voltage of voltage sensor 54 is rising, it determines that there is a continuity failure in negative-side cutting circuit 47 (step S140), and ends this process without starting boost charging.On the other hand, if it is determined that the sensor voltage of voltage sensor 54 is not rising, it determines that negative-side cutting circuit 47 is normal (step S150).

[0024] If it is determined that negative-side shutoff circuit 47 is normal, then the inverter 24 is switched and controlled to charge capacitor 53 so that the voltage across capacitor 53 is maintained at a first predetermined voltage (step S160), and the negative-side shutoff circuit 47 is turned on (cutoff is released) (step S170). Then, the inverter 24 is switched and controlled to discharge capacitor 53 so that the voltage across capacitor 53 becomes a second predetermined voltage (e.g., 300 V) that is lower than the first predetermined voltage (step S170), and it is determined whether the sensor voltage of voltage sensor 54 has dropped (step S180). Because the neutral-point-side shutoff circuit 52 is off (cutoff) and the negative-side shutoff circuit 47 is on (cutoff is released), the sensor voltage does not drop when the neutral-point-side shutoff circuit 52 is normal, but the sensor voltage drops when a continuity fault occurs in the neutral-point-side shutoff circuit 52. Therefore, if it is determined that the sensor voltage of voltage sensor 54 has dropped, it determines that there is a continuity fault in neutral point side interrupt circuit 52 (step S200), and ends this process without starting boost charging.On the other hand, if it is determined that the sensor voltage of voltage sensor 54 has not dropped, it determines that neutral point side interrupt circuit 52 is normal (step S210).

[0025] If it is determined that the neutral point side interruption circuit 52 is normal, the neutral point side interruption circuit 52 is turned on (released from interruption) (step S220), boost charging is started (step S230), and this process ends.

[0026] In the electric vehicle 20 of the embodiment described above, when charging of the battery 26 by boost charging using the charger 40 begins, the system main relay 28 is turned on and the neutral relay 51 is turned on while both the neutral point side breaking circuit 52 and the negative pole side breaking circuit 47 are turned off (shut down). Then, each phase of the motor 22 and each phase of the inverter 24 function as a boost circuit to charge the capacitor 53 until the voltage of the capacitor 53 reaches a first predetermined voltage, and when the sensor voltage of the voltage sensor 54 rises, it is determined that a continuity fault has occurred in the negative pole side breaking circuit 47. This makes it possible to determine a continuity fault in the negative pole side breaking circuit 47 without providing any additional configuration.

[0027] In the electric vehicle 20 of this embodiment, when it is determined that the negative side interrupting circuit 47 is normal, the negative side interrupting circuit 47 is turned on (disconnected) while the voltage of the capacitor 53 is maintained at the first predetermined voltage, the charge is discharged from the capacitor 53 so that the voltage of the capacitor 53 becomes a second predetermined voltage that is lower than the first predetermined voltage, and when the sensor voltage of the voltage sensor 54 drops, it is determined that a continuity fault has occurred in the neutral point side interrupting circuit 52. In this way, it is possible to determine that a continuity fault has occurred in the neutral point side interrupting circuit 52 without providing any additional configuration.

[0028] In the electric vehicle 20 of this embodiment, boost charging is started when it is determined that both the negative pole side breaking circuit 47 and the neutral point side breaking circuit 52 are normal, so boost charging can be performed more appropriately.

[0029] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problems" section will be described below. In the embodiment, the battery 26 corresponds to the "battery," the motor 22 corresponds to the "three-phase AC motor," the inverter 24 corresponds to the "inverter," the system main relay 28 corresponds to the "system main relay," the external charging connector 42 corresponds to the "external charging connector," the charger 40 corresponds to the "DC charger," and the electronic control unit 60 corresponds to the "control device." Furthermore, the power line 30 corresponds to the "power line", the charging power line 43 corresponds to the "charging power line", the bypass relay 46 corresponds to the "bypass relay", the neutral point charging line 50 corresponds to the "neutral point charging line", the neutral point relay 51 corresponds to the "neutral point relay", the neutral point side shut-off circuit 52 corresponds to the "neutral point side shut-off circuit", the negative side shut-off circuit 47 corresponds to the "negative side shut-off circuit", the capacitor 53 corresponds to the "capacitor", and the voltage sensor 54 corresponds to the "voltage sensor".

[0030] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, because the embodiments are examples for specifically explaining the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0031] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to these embodiments, and it goes without saying that the present disclosure can be embodied in various forms without departing from the spirit of the present disclosure. [Industrial Applicability]

[0032] The present disclosure is applicable to the electric vehicle manufacturing industry and the like. [Explanation of symbols]

[0033] 20 electric vehicle, 22 motor, 24 inverter, 26 battery, 28 system main relay, 30 power line, 32 filter, 34 capacitor, 40 charger, 42 external charging connector, 43 charging power line, 44 positive side line, 45 negative side line, 46 bypass relay, 47 negative side cutoff circuit, 48 charging relay, 49 filter, 50 neutral point charging line, 51 neutral point relay, 52 neutral point side cutoff circuit, 53 capacitor, 54 voltage sensor, 55 leakage detection circuit, 60 electronic control unit, CHRB positive side relay, CHRG negative side relay, SMRB positive side relay, SMRG negative side relay, SMRP precharge relay, R precharge resistor.

Claims

1. An electric vehicle including: a battery; a three-phase AC motor; an inverter that drives the three-phase AC motor using power from the battery; a system main relay with a pre-charge function that is provided in a power line that connects the battery and the inverter; a DC charger that charges the battery using external DC power supplied from an external charging connector; and a control device, The DC charger includes a charging power line connected between the external charging connector and the inverter on the power line, a bypass relay attached to a positive side line of the charging power line, a neutral point charging line connecting a neutral point of the three-phase AC motor to the external charging connector on the positive side line of the charging power line and the bypass relay, a neutral point relay attached to the neutral point charging line, and a power line connected from the neutral point relay on the neutral point charging line to the external charging connector. a neutral point side interrupting circuit connected to the external charging connector side of the charging power line, a negative side interrupting circuit attached to the negative side line of the charging power line, a capacitor connected to the power line side of the negative side line of the charging power line from the negative side interrupting circuit and between the neutral point relay and the neutral point side interrupting circuit of the neutral point charging line, and a voltage sensor connected to the external charging connector side of the neutral point side interrupting circuit of the neutral point charging line and to the external charging connector side of the negative side line of the charging power line, the control device determines that a continuity fault has occurred in the negative side shutoff circuit when a voltage rise is detected by the voltage sensor while the inverter is controlled so that the voltage of the capacitor becomes a first predetermined voltage with the system main relay and the neutral point relay turned on and the neutral point side shutoff circuit and the negative side shutoff circuit turned off; An electric vehicle characterized by:

2. The electric vehicle according to claim 1, the control device turns on the neutral point side interrupting circuit when it determines that no continuity fault has occurred in the negative pole side interrupting circuit, and determines that a continuity fault has occurred in the neutral point side interrupting circuit when a voltage drop is detected by the voltage sensor when the control device controls the inverter so that the capacitor voltage becomes the first predetermined voltage and then controls the inverter so that the capacitor voltage becomes a second predetermined voltage that is lower than the first predetermined voltage. Electric car.

3. 3. The electric vehicle according to claim 2, When the control device determines that a continuity fault has occurred in the negative pole side interrupting circuit or / and the neutral point side interrupting circuit, the control device prohibits charging of the battery using the external DC power. Electric car.

Images