JP5152085B2 - Electric vehicle power supply control device - Google Patents

Description

  The present invention relates to a power supply control device for an electric vehicle, and more particularly to a technique for shifting to battery-less running when a battery is abnormal.

  Conventionally, in an electric vehicle such as a hybrid vehicle, when a secondary battery or a large-capacity battery that accumulates power fails or a charging circuit that charges them fails, the generator and the motor are directly connected to generate power. So-called battery-less traveling has been proposed that enables the vehicle to travel by driving the electric motor using the generated electric power as it is.

  For example, Patent Document 1 discloses the following technique. That is, in the configuration of FIG. 5, the engine EG is feedback-controlled with respect to the target rotational speed NE *, and the operation of the inverter P1 of the generator GN is stopped when a failure occurs. When the generator GN rotates at a predetermined number of revolutions, a counter electromotive voltage is generated in each phase coil of the generator. When the motor MG is connected as a load, a current flows through the protective diode of the inverter P1, Power generation is performed. Since the generated power is consumed by the motor MG as it is, the power generation amount and the consumption amount are balanced. At this time, connection between inverters P1, P2 and battery BT is interrupted by system main relay SMR.

  Specifically, the system controller SCNT determines whether or not a failure has occurred in the battery BT, the inverter P1 of the generator GN, or the like (step SA). If it is determined that a failure has occurred, the system controller SCNT Processing to turn off the main relay SMR is performed (step SB). As a result, battery BT is disconnected from the circuits of inverters P1 and P2. Next, the rotational speed of each axis is read (step SC). Subsequently, the accelerator pedal depression amount AP is detected (step SD), and the rotation speed of the generator GN is changed based on the required output of the vehicle obtained from the depression amount AP and the rotation speed of the drive shaft DS (step SE). ). Then, the motor MG is controlled in accordance with the request of the vehicle (step SF).

JP 2001-329884 A

  When the system main relay is turned off when the battery is abnormal, in order to prevent welding of the main relay, it is necessary to first shut off the inverters P1 and P2 in order to shut off the generator GN and the motor MG with power in and out. .

  However, if the generator GN and the motor MG are shut off at a high rotation speed, such as during high-speed running or high engine load operation, a large counter electromotive force is generated. In general, power from a battery is boosted by a boost converter and then supplied to inverters P1 and P2. A smoothing capacitor for smoothing voltage fluctuation is provided between the boost converter and inverters P1 and P2. When the capacity of the smoothing capacitor is small, it becomes an overvoltage state, and it may be difficult to shift to battery-less running. In particular, recently, the capacity of the smoothing capacitor is required to be reduced in order to cope with a small vehicle (a vehicle with a small output) and to reduce the cost. In this case, overvoltage can be a particular problem.

  According to the present invention, even when an abnormality occurs in a battery mounted on an electric vehicle such as a hybrid vehicle, the relay for connecting the battery to the power supply circuit can be reliably turned off to smoothly shift to battery-less traveling. Provide technology.

  The present invention relates to a battery, a boost converter that boosts a DC voltage from the battery, a relay provided between the battery and the boost converter, and a first converter that converts the DC voltage from the boost converter into an AC voltage. 1 inverter and 2nd inverter, a 1st motor generator which is connected to the engine while being connected to the 1st inverter, and is generated by at least a part of motive power from the engine, and is connected to the 2nd inverter and a drive wheel Connected to the second motor generator for driving the driving wheel, and when the battery is abnormal, the gate of the boost converter is controlled to be off, and between the input side voltage VL and the output side voltage VH of the boost converter <Controlling the first inverter and the second inverter so that the relationship of VH is maintained And controlling the power of said first motor generator and the second motor-generator Te, thereafter, characterized by a control means for turning off controlling the relay.

  In one embodiment of the present invention, the control means limits the required torque of the first motor generator and the second motor generator prior to turning off the gate of the boost converter.

  In another embodiment of the present invention, the control means determines whether or not the current value of the battery is within a specified value prior to turning off the relay. The relay is controlled to be turned off, and when the specified value is exceeded, the relay is turned off after the gates of the first inverter and the second inverter are turned off.

  In another embodiment of the present invention, the control means sets an arbitrary voltage that is equal to or higher than the input voltage VL and lower than a specified overvoltage threshold Vth as a target value of the output voltage VH. Then, the electric power of the first motor generator and the second motor generator is feedback controlled so that the actual output side voltage matches the target value.

  In another embodiment of the present invention, the control means executes the control when the first motor generator and the second motor generator are in a high rotation state equal to or higher than a predetermined rotation speed.

  According to the present invention, even when an abnormality occurs in a battery mounted on an electric vehicle such as a hybrid vehicle, the relay for connecting the battery to the power supply circuit is reliably turned off to smoothly shift to battery-less traveling. Can do.

It is a configuration block diagram of an embodiment. It is control explanatory drawing at the time of battery abnormality of embodiment. It is a processing flowchart of an embodiment. It is another process flowchart of embodiment. It is a block diagram of a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the configuration of the power supply control device according to this embodiment. This device includes a power generator circuit, an inverter main circuit, and a motor generator driven by the inverter main circuit, and is mounted on, for example, a hybrid vehicle.

  Motor generator MG1 is connected to engine ENG and operates as a motor that can start engine ENG, and also operates as a generator driven by engine ENG. Motor generator MG2 is connected to a drive wheel (not shown) and is incorporated as a motor for driving the drive wheel. Motor generators MG1, MG2 include U-phase, V-phase, and W-phase three-phase coils as stator coils. One end of each phase coil forming the three-phase coil is connected to each other to form a neutral point. The other end of each phase coil is connected to the connection point of the switching transistor of each phase arm of inverter 104 or inverter 106.

  The positive electrode of the battery 100 as a power source is connected to the power supply line (positive side) via the system main relay SMR, and the negative electrode of the battery 100 is connected to the ground line (negative side) via the system main relay SMR. Capacitor Cf is connected between the power supply line and the ground line. The battery 100 is a DC power source that can be charged and discharged, and is composed of, for example, a nickel metal hydride battery or a lithium ion battery. Battery 100 outputs DC power to boost converter 102. Battery 100 is charged by boost converter 102 during regenerative braking of the vehicle. Instead of the battery 100, a large capacity capacitor or a fuel cell may be used.

  Boost converter 102 includes a reactor L, switching transistors Q1 and Q2, and diodes D1 and D2. Switching transistors Q1 and Q2 are connected in series between the power supply line and the ground line. Diodes D1 and D2 are connected in antiparallel to the switching transistors Q1 and Q2, respectively. One end of the reactor L is connected to the connection point of the switching transistors Q1 and Q2, and the other end is connected to the power supply line. As the switching transistors Q1 and Q2, an npn transistor, IGBT, power MOSFET, or the like can be used. Capacitor Cm is connected between the power supply line and the ground line. The capacitor Cm smoothes voltage fluctuation between the power supply line and the ground line.

  Boost converter 102 boosts the DC voltage from battery 100 using reactor L based on the signal from control device 50, and outputs the boosted voltage to the power supply line. That is, boost converter 102 boosts a DC voltage by accumulating current flowing according to switching operation of switching transistor Q2 as magnetic field energy in reactor L, and supplies power via diode D1 at the timing when switching transistor Q2 is turned off. Output to line.

  Inverter 104 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm, and W-phase arm are connected in parallel with each other between the power supply line and the ground line. The U-phase arm includes switching transistors connected in series with each other, the V-phase arm includes switching transistors connected in series with each other, and the W-phase arm includes switching transistors connected in series with each other. A diode is connected in antiparallel to each switching transistor.

  Inverter 104 converts a DC voltage supplied from the power supply line into a three-phase AC voltage based on the PWM signal from control device 50 and outputs it to motor generator MG1. Inverter 104 receives the output from engine ENG, converts the three-phase AC voltage generated by motor generator MG1 into a DC voltage based on a signal from control device 50, and outputs the DC voltage to the power supply line.

  Inverter 106 includes a U-phase arm, a V-phase arm, and a W-phase arm. The U-phase arm, V-phase arm, and W-phase arm are connected in parallel with each other between the power supply line and the ground line. The U-phase arm includes switching transistors connected in series with each other, the V-phase arm includes switching transistors connected in series with each other, and the W-phase arm includes switching transistors connected in series with each other. A diode is connected in antiparallel to each switching transistor.

  Inverter 106 converts a DC voltage received from the power supply line into a three-phase AC voltage based on the PWM signal from control device 50 and outputs the same to motor generator MG2. In addition, during regenerative braking of the vehicle, inverter 106 receives the rotational force from the drive wheels, converts the three-phase AC voltage generated by motor generator MG2 into a DC voltage, and outputs the DC voltage to the power supply line. A 12V auxiliary battery 112 is connected between the power supply line and the ground line via the DC / DC converter 110, and an air conditioner compressor 116 is connected via the inverter 114.

  In such a configuration, when the control device 50 detects that an abnormality has occurred in the battery 100 due to the input of the battery abnormality signal, the control device 50 controls the system main relay SMR to be turned off, that is, battery-less traveling, that is, The motor generator MG2 is driven using the electric power generated by the motor generator MG1 as it is. However, in order to prevent the system main relay SMR from being welded, it is necessary to turn off the SMR in a state where no current is supplied to the SMR.

  However, if the operation of inverters 104 and 106 is stopped in order to cut off the energization of SMR, motor generators MG1 and MG2 generate a large counter electromotive voltage at a high speed, exceeding the rated overvoltage threshold. It can happen.

  Therefore, in the present embodiment, when the battery 100 is abnormal, the control device 50 does not stop the operation of the inverters 104 and 106 but allows the operation of the inverters 104 and 106 and the operation of the boost converter 102 and the DC / DC. The operations of the DC converter 110 and the inverter 114 are stopped.

  On the other hand, when allowing the operation of inverters 104 and 106 to stop the operation of boost converter 102, power is supplied from battery 100 to motor generators MG1 and MG2 via a protective diode connected in reverse parallel to the switching transistor of the boost converter. A situation that flows may occur.

  Therefore, as schematically shown by an arrow in FIG. 2, the control device 50 includes a voltage VL on the battery 100 side (an input side voltage of the boost converter 102) and an inverter to prevent the flow of power from the battery 100. The power of the motor generators MG1 and MG2 is balanced so that the relationship of VH> VL is always satisfied with the voltage VH on the 104 and 106 side (the output side voltage of the boost converter 102).

  At this time, control device 50 limits the torque of motor generators MG1, MG2 to a value as small as possible. As a result, it is possible to reliably avoid a situation where VH ≦ VL due to a deviation in the power balance due to a disturbance such as slip or tire riding. An example of torque limitation of motor generators MG1 and MG2 is to cut the required torque. Of course, the cut of the required torque is a temporary measure until the SMR is turned off. After the SMR is turned off and the batteryless running is started, the normal required torque is restored.

  Thus, by limiting the torque of motor generators MG1 and MG2 and driving inverters 104 and 106 so as to control the electric power balance of motor generators MG1 and MG2 so that VH> VL, SMR can be achieved without arcing. It can be controlled off. Thereby, it can transfer to battery-less driving | running | working smoothly, without welding SMR.

  In battery-less travel, control device 50 reads the driver's request from the amount of accelerator pedal depression and the rotational speed of the drive shaft, and controls the power (rotation speed x torque) output to motor generator MG2. The requested power is generated using the back electromotive force of motor generator MG1. The energy source generated by motor generator MG1 is engine ENG, and the output of engine ENG is controlled in accordance with the increase or decrease in the amount of power generation.

  Since the engine ENG is feedback controlled to the target rotational speed, if the power generation amount of the motor generator MG1 increases and the rotational speed decreases, the intake air amount and the fuel injection amount are increased and the output of the engine ENG increases. .

  Control device 50 limits the torque of motor generators MG1 and MG2 so as to satisfy VH> VL and controls the power balance of motor generators MG1 and MG2 when turning off SMR. As the control, a target VH that is greater than or equal to VL and less than the overvoltage threshold is set, and a deviation from the actual VH is applied to a torque request to the motor generators MG1 and MG2, thereby balancing MG1 and MG2.

  Further, at the time of control switching, it is desirable to prevent the control failure due to a sudden change by controlling the actual VH to be an initial value and shifting to the target VH stepwise. For example, VH is linearly changed so as to shift to the target VH after time t1 after the control switching, or VH is changed stepwise. Of course, the difference between the actual VH and the target VH is calculated, and when the difference is greater than or equal to a threshold value, the process proceeds to the target VH stepwise. You may switch to

  FIG. 3 shows a processing flowchart when the battery 100 is abnormal in the present embodiment. In the present embodiment, since the operation of the inverters 104 and 106 is allowed as described above, it is assumed that only the battery 100 is abnormal and the inverters 104 and 106 operate normally.

  When abnormality of battery 100 is detected, the control device first limits the torque by cutting the required torque of motor generators MG1, MG2 to 0 (S101). Next, it is determined whether or not the engine ENG is in operation (S102). If the engine ENG is not in operation, it is not possible to shift to battery-less travel in the first place, so the engine ENG is started (S103), and it is determined whether the engine ENG has been successfully started (S104). If the engine ENG cannot be started, the traveling is immediately stopped.

  On the other hand, if the engine ENG is already in operation, or if the engine ENG is not in operation and the start is successful, then the control device sets a target VH (S105). The target VH can be set to an arbitrary voltage V that satisfies VL ≦ V <Vth when the overvoltage threshold is Vth. For example, when the battery voltage is 200V and the overvoltage threshold is 800V, the intermediate value 500V is set as the target VH.

  After setting the target VH, the motor generators MG1 and MG2 are feedback-controlled so that the actual VH becomes the set target VH (S106). That is, a deviation amount between the actual VH and the target VH is detected, and this deviation amount is applied to the torque demands of the MG1 and MG2, thereby controlling the actual VH to match the target VH.

  After the power balance of MG1 and MG2 is controlled and stabilized so that VL <VH, the control device allows the gates of MG1 and MG2, that is, the gates of the inverters 104 and 106 as they are. Turns off the gate of the boost converter 102, the converter 110, and the inverter 114 (S107).

  Thereafter, the SMR is turned off (S108), and after the battery 100 is disconnected from the power supply circuit, the operation of the gates turned off in S107, specifically, the gates of the boost converter 102, the converter 110, and the inverter 114 is permitted (S109). Transition to battery-less travel (S110).

  In the process flowchart of FIG. 3, the process of S107 may be executed prior to the process of S105 or S106. That is, first, the gate of boost converter 102 may be turned off, and thereafter, MG1 and MG2 may be feedback controlled so as to reach target VH.

  Further, in the process flowchart of FIG. 3, the SMR current is basically cut off by turning off the boost converter 102 and controlling so that VL <VH. Since there is a risk of welding when energization occurs, the SMR may be turned off after further detecting the energization current of the SMR and confirming whether it is within a specified range.

  FIG. 4 shows a processing flowchart in this case. The processing of S201 to S207 is the same as the processing of S101 to S107 in FIG.

  On the other hand, after the gate of boost converter 102 is turned off in S207, the control device determines whether or not current value IB of battery 100 detected by the current sensor is within a specified value (S208). The specified value is a value near zero. If the current value of the battery 100 is within the predetermined value, the SMR is turned off (S210). If not, the SMR is turned off after the gates of the inverters 104 and 106 are turned off (S209). ). In the processing in S209, the highest priority is given to turning off SMR with no electric arc.

  As described above, in this embodiment, the gates of the inverters 104 and 106 are not turned off as in the prior art, but the operation of the inverters 104 and 106 is allowed and the balance of the electric power of the motor generators MG1 and MG2 is controlled. Thus, it is possible to prevent overvoltage, reliably turn off the SMR, and shift to battery-less running.

  In the present embodiment, the overvoltage is particularly problematic when the motor generators MG1 and MG2 are rotating at high speed, specifically during high-speed driving or during high engine load operation, so that the motor generators MG1 and MG2 are rotating at high speed. The control of the present embodiment may be performed only at times, and otherwise the same control as in the conventional case may be performed. Specifically, it is determined whether or not the rotational speeds of motor generators MG1 and MG2 are equal to or higher than a predetermined threshold rotational speed, and this determination is performed when it is determined that the rotational speed is equal to or higher than the threshold rotational speed and high. Transition to form control. It may be determined whether or not the vehicle speed is equal to or higher than the threshold vehicle speed. If the vehicle speed is equal to or higher than the threshold vehicle speed, the control of this embodiment may be performed.

  In the present embodiment, the battery 100 is exemplified as the power source, but a large capacity capacitor or a fuel cell may be used instead of the battery 100. The present invention is not limited to the battery 100.

  50 control device, 100 battery, 102 boost converter, 104 inverter (first inverter), 106 inverter (second inverter), MG1 motor generator (first motor generator), MG2 motor generator (second motor generator).

Claims (5)

Battery,
A boost converter for boosting a DC voltage from the battery;
A relay provided between the battery and the boost converter;
A first inverter and a second inverter for converting a DC voltage from the boost converter into an AC voltage;
A first motor generator that is connected to the first inverter and connected to the engine, and that generates power using at least part of the power from the engine;
A second motor generator connected to the second inverter and connected to the drive wheel to drive the drive wheel;
When the battery is abnormal, the gate of the boost converter is controlled to be off, and the first inverter and the voltage VL <VH are maintained between the input side voltage VL and the output side voltage VH of the boost converter. Control means for controlling the electric power of the first motor generator and the second motor generator by controlling the second inverter, and thereafter controlling the relay to be turned off;
A power supply control device for an electric vehicle characterized by comprising: The apparatus of claim 1.
The control means limits the torque demanded by the first motor generator and the second motor generator prior to turning off the gate of the boost converter. The apparatus of claim 1.
Prior to turning off the relay, the control means determines whether or not the battery current value is within a specified value. If the current value is within the specified value, the control means turns off the relay and exceeds the specified value. The power supply control device for an electric vehicle, wherein the relay is turned off after the gates of the first inverter and the second inverter are turned off. In the apparatus in any one of Claims 1-3,
The control means sets, as a target value of the output side voltage VH, an arbitrary voltage that is not less than the input side voltage VL and less than a specified overvoltage threshold Vth, and the actual output side voltage is the target value. A power supply control device for an electric vehicle, wherein the electric power of the first motor generator and the second motor generator is feedback-controlled so as to match In the apparatus in any one of Claims 1-4,
The power control apparatus for an electric vehicle, wherein the control means executes the control when the first motor generator and the second motor generator are in a high rotation state equal to or higher than a predetermined rotation speed.

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