JP5532995B2 - Power control device - Google Patents

Description

  The present invention relates to a power control apparatus including a buck-boost converter that converts a voltage between a battery and a power device.

  Conventionally, this type of power control apparatus includes a battery that can exchange power with a motor as a power device via an inverter, and a boost converter that boosts the power from the battery to a target voltage and supplies the boosted voltage to the inverter. The thing is proposed (for example, refer patent document 1). In this power control apparatus, when an overvoltage state in which the output voltage of the boost converter exceeds the target voltage occurs, the overvoltage state is eliminated by executing step-down control of the boost converter for reducing the output voltage.

JP 2009-55699 A

  In the power control device described above, if any abnormality occurs in the boost converter or the like and the step-down control cannot be performed, the output voltage of the boost converter is reduced as described above to eliminate the overvoltage state, or the power generated by the motor Can not be stepped down and supplied to the battery. Therefore, in the power control device as described above, it is required to detect early and surely whether or not the step-down control of the step-up converter can be executed.

  The power control device of the present invention is a power control device including a step-up / down converter that converts a voltage between a battery and a power device. And

  The power control apparatus of the present invention employs the following means in order to achieve the main object described above.

The power control device of the present invention includes a battery capable of exchanging power with a power device, a buck-boost converter that converts a voltage between the power device, and power that is a voltage on the power device side of the buck-boost converter. A voltage sensor for detecting a device-side voltage, and controlling the step-up / down converter so that the power device-side voltage becomes a target voltage, and lowering the power device-side voltage when the power device-side voltage is higher than the target voltage And a control means for performing step-down control of the step-up / down converter for causing
When the power device side voltage after execution of the step-down control is lower than the power device side voltage before execution of the step-down control, it is determined that the buck-boost converter is normal, and after the step-down control is executed When the power equipment side voltage is not lower than the power equipment side voltage before execution of the step-down control and current is flowing through the battery during the step-down control, the buck-boost converter is normal and the It is determined that an abnormality has occurred in the voltage sensor, and the power device side voltage after execution of the step-down control is not lower than the power device side voltage before execution of the step-down control and the step-down control is being executed. And an abnormality determining means for determining that an abnormality has occurred in the buck-boost converter when no current is flowing through the battery. .

  In the power control device of the present invention, when the power equipment side voltage, which is the voltage on the power equipment side of the buck-boost converter, is higher than the target voltage, step-down control of the buck-boost converter is performed to reduce the power equipment side voltage. . When such step-down control is executed, if the buck-boost converter is normal, the power from the power device side is stepped down and supplied to the battery, and the voltage on the power device side decreases. Therefore, it is possible to determine that the buck-boost converter is normal when the power device side voltage after execution of the step-down control is lower than the power device side voltage before execution of the step-down control, and the power device after execution of the step-down control. When the side voltage is not lower than the power equipment side voltage before the step-down control is performed, and the current is flowing through the battery during the step-down control, the buck-boost converter is normal and the voltage sensor is abnormal. If the power equipment side voltage after the step-down control is not lower than the power equipment side voltage before the step-down control is performed and no current is flowing to the battery during the step-down control, It can be determined that an abnormality has occurred in the converter. Thereby, in the power control device of the present invention, it is possible to more appropriately determine whether or not the step-down control of the buck-boost converter can be executed.

It is a schematic block diagram of the electric vehicle 10 carrying the electric power control apparatus which concerns on one Example of this invention. It is explanatory drawing which shows an example of the map for a duty ratio setting. It is explanatory drawing which shows an example of the time change of duty ratio Duty, the motor side voltage VH, and the battery current Ib in execution of step-down control. It is a flowchart which shows an example of the pressure | voltage fall control availability determination routine performed by the electronic control unit 40 of an Example.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a schematic configuration diagram of an electric vehicle 10 equipped with a power control apparatus according to an embodiment of the present invention. As shown in the figure, an electric vehicle 10 according to an embodiment includes, for example, a motor 11 that is configured as a synchronous generator motor and has a rotor connected to drive wheels 18a and 18b via a differential gear 16, and the motor 11 and the electric power A battery 12 that can be exchanged, for example, a lithium ion secondary battery or a nickel hydride secondary battery, an inverter 22 that is interposed between the motor 11 and the battery 12 and drives the motor 11, and an electric power from the battery 12 The step-up / step-down converter 23 that can step up the voltage and supply the electric power from the inverter 22 to the battery 12 and the inverter 22 and the step-up / down converter 23 are driven and controlled, and the entire vehicle is controlled. And an electronic control unit 40 and the like.

  The inverter 22 is configured as a well-known inverter capable of rotating the motor 11 by supplying a phase current for forming a rotating magnetic field to the three-phase coil of the motor 11 by switching a plurality of switching elements. The step-up / step-down converter 23 is a well-known step-up / step-down converter composed of two transistors Tr1, Tr2 and two diodes D1, D2 connected in parallel to the transistors Tr1, Tr2 and a reactor L. Connected to the inverter 22. As a result, the transistors Tr1 and Tr2 are turned on / off using a predetermined duty ratio to boost the power from the battery 12 side by the step-up / down converter 23 and supply the boosted power to the inverter 22 or power from the inverter 22 side. Can be stepped down and supplied to the battery 12. Further, a smoothing capacitor 31 for smoothing the voltage is disposed between the buck-boost converter 23 and the battery 12, and a smoothing capacitor 32 for smoothing the voltage between the buck-boost converter 23 and the inverter 22. A resistance element 33 capable of discharging the electric charge accumulated in the smoothing capacitor 32 is disposed.

  The electronic control unit 40 is configured as a microprocessor centered on a CPU, and in addition to the CPU, a ROM that stores a processing program, a RAM that temporarily stores data, and a timer that executes time-measurement processing in response to a time-measurement command , An input / output port, a communication port, etc. (both not shown). The electronic control unit 40 includes an ignition signal from an ignition switch (start switch) 51, an accelerator opening from an accelerator pedal position sensor 55 that detects the depression amount of an accelerator pedal 54, a vehicle speed from a vehicle speed sensor 58, a terminal of a battery 12 A battery current Ib, which is a current flowing through the battery 12 detected by a current sensor (not shown) attached to a power line connected between them, and a buck-boost converter detected by a voltage sensor 34 installed between terminals of the smoothing capacitor 31 23, the battery side voltage VL which is the voltage on the battery 12 side, and the motor side voltage VH which is the voltage on the motor 11 side of the buck-boost converter 23 detected by the voltage sensor 35 installed between the terminals of the smoothing capacitor 32 Side voltage) via the input port It is a force. From the electronic control unit 40, a switching control signal to the inverter 22, a switching control signal to the buck-boost converter 23, and the like are output via an output port. The electronic control unit 40 also calculates data relating to the motor 11 such as the number of rotations of the motor 11 based on a signal from a rotational position detection sensor (not shown) that detects the rotational position of the rotor of the motor 11.

  When the electric vehicle 10 of the embodiment travels, the electronic control unit 40 sets the required torque required for the motor 11 for traveling according to the accelerator opening from the accelerator pedal position sensor 55 and the vehicle speed from the vehicle speed sensor 58. Set. Then, based on the set required torque and the rotation speed of the motor 11, the target voltage VH * to be applied to the inverter 22 is set so as to increase as the required torque and the rotation speed of the motor 11 increase. The transistors Tr1 and Tr2 of the step-up / step-down converter 23 are subjected to switching control so that the target voltage VH * is reached, and the inverter 22 is subjected to switching control so that torque corresponding to the required torque is output from the motor 11.

  Further, when an overvoltage state occurs in which the motor side voltage VH is higher than the target voltage VH *, the electronic control unit 40 turns off the transistor Tr2 (lower arm) of the buck-boost converter 23 so that the motor voltage VH decreases. At the same time, step-down control is performed to turn on / off the transistor Tr1 (upper arm) using a predetermined duty ratio Duty. In the embodiment, the relationship between the duty ratio Duty used for step-down control and the elapsed time t from the start of step-down control is determined in advance and stored in a ROM (not shown) of the electronic control unit 40 as a duty ratio setting map. When executing the control, the duty ratio Duty corresponding to the elapsed time t is derived from the map. FIG. 2 is an explanatory diagram showing an example of the duty ratio setting map, and FIG. 3 is an explanatory diagram showing an example of a time change of the duty ratio Duty, the motor side voltage VH, and the battery current Ib during the step-down control. is there. As shown in FIG. 2, the duty ratio Duty gradually increases with the passage of time from the start of the step-down control, and is 100% (transistor) when a predetermined time t1 (for example, about 3 to 5 seconds) elapses. It is determined that Tr1 is always on. By performing step-down control using the duty ratio Duty determined in this way, the motor-side voltage VH is supplied to the battery side while suppressing an excessive current from flowing through the transistor Tr1 of the buck-boost converter 23, the battery 12, and the like. The overvoltage state can be eliminated by once reducing the voltage to the voltage VL. In addition, since the power from the inverter 22 side of the step-up / down converter 23 is supplied to the battery 12 during the step-down control, a charging current flows through the battery 12. After the execution of the step-down control, the electronic control unit 40 can further execute an abnormality determination process for determining whether or not the step-down control of the step-up / down converter 23 can be executed, and can perform the step-down control of the step-up / down converter 23. When it is determined that the step-up / down converter 23 is returned to the normal control state, the inverter 22 and the like are controlled so that a predetermined retreat travel is executed when it is determined that the step-down control of the step-up / down converter 23 is not possible. .

  Next, an abnormality determination process for determining whether or not the step-down control of the step-up / down converter 23 can be executed will be described. FIG. 4 is a flowchart illustrating an example of a step-down control availability determination routine executed by the electronic control unit 40 of the embodiment. This routine is executed by the electronic control unit 40 after completion of the above-described step-down control.

  When the step-down control enable / disable determination routine is executed, the electronic control unit 40, the motor voltage VHb before the step-down control is executed, the motor voltage VHa from the voltage sensor 35 (after the step-down control is executed), and the battery charge flag Fb. , And the flag F1, data necessary for determining the abnormality of the step-up / down converter 23 is input (step S100). Here, the motor voltage VHb before the step-down control is executed is detected by the voltage sensor 35 and stored in a RAM (not shown) of the electronic control unit 40 before the step-down control is executed. The battery charge flag Fb is set to a value of 1 when a charging current of a predetermined value (for example, about 6 A) or more flows through the battery 12 during the step-down control, and the battery 12 during the step-down control. When a charging current of a predetermined value or more does not flow, the flag is set to a value of 0, and the flag F1 is a flag set to a value of 0 as an initial value at the start of traveling. If data is input in step S100, it is determined whether or not the motor side voltage VHa is lower than the motor side voltage VHb before the step-down control is executed (step S110). Here, if the step-up / down converter 23 is normal, the motor-side voltage VHa after execution of the step-down control is lower than the motor-side voltage VHb before execution of the step-down control. Therefore, when it is determined in step S110 that the motor-side voltage VHa after the step-down control is performed is lower than the motor-side voltage VHb before the step-down control is performed, it is determined whether or not the flag F1 is a value 0 ( In step S120), when it is determined that the flag F1 is 0, no step-down control of the transistor Tr1 of the step-up / step-down converter 23 that disables step-down control or an abnormality of the voltage sensor 35 has occurred, and step-down control is executed. And the flag F1 is set to 1 (step S130), and this routine is terminated. In this case, since the step-up / down converter 23 and the like are normal, the electronic control unit 40 returns the step-up / down converter 23 to the normal control state. Note that the process of step S120 may determine whether or not the motor-side voltage VHa after the step-down control is performed and the battery-side voltage VL after the step-down control are approximately the same value.

  On the other hand, when it is determined in step S120 that the flag F1 is 1, the flag F2, which is set to 0 as the initial value, is set to 1 (step S140), and this routine ends. That is, when it is determined that the flag F1 is 1, it is determined in step S110 that the motor side voltage VHa after execution of the step-down control is lower than the motor side voltage VHb before execution of the step-down control. Although it is unlikely that the transistor Tr1 of the step-up / down converter 23 has been turned off, an overvoltage condition has occurred twice during a single trip, so some abnormality has occurred in the system. there is a possibility. Therefore, when the flag F2 is set to the value 1 in step S140, the electronic control unit 40 prevents the occurrence of another overvoltage state or other trouble before the transistor Tr1 of the step-up / down converter 23. Is always turned on, and the transistor Tr2 is always turned off, so that the electric power from the battery 12 is supplied to the inverter 22 side without being stepped up by the step-up / down converter 23, and the retreat traveling is performed.

  If it is determined in step S110 that the value of the motor side voltage VHa after execution of the step-down control is not lower than the motor side voltage VHb before execution of the step-down control, the battery charge flag input in step S100 It is determined whether or not Fb is a value 1 (step S150), and when it is determined that the battery charge flag Fb is a value 1, it means that a charging current has flowed through the battery 12 during the step-down control. Therefore, it is determined that the step-up / step-down converter 23 is normal and the step-down control has been normally executed, and it is determined that an abnormality has occurred in the voltage sensor 35 (step S160), and this routine is terminated. In this case, since it is impossible to accurately detect the value of the motor side voltage VH and the boosting of the battery side voltage VL by the step-up / step-down converter cannot be performed properly, the electronic control unit 40 has the step-up / step-down voltage. While the transistor Tr1 of the converter 23 is always turned on and the transistor Tr2 is always turned off, the electric power from the battery 12 is supplied to the inverter 22 side without being stepped up by the step-up / down converter 23, and the retreat traveling is performed.

  On the other hand, when it is determined in step S150 that the battery charge flag Fb is a value of 0, the charging current is not flowing in the battery 12 during the execution of the step-down control, so that the step-down control is normally performed. It is determined that it has not been executed, it is determined that an off-failure of the transistor Tr1 of the step-up / down converter 23 has occurred (step S170), and this routine ends. In this case, the electronic control unit 40 shuts down the buck-boost converter 23 (turns off both the transistors Tr1 and Tr2), and steps down the power from the inverter 22 by the buck-boost converter 23 and supplies it to the battery 12. While prohibiting, the electric power from the battery 12 is supplied to the inverter 22 side without being stepped up by the step-up / down converter 23, and the retreat traveling is performed.

  In the electric vehicle 10 equipped with the power control apparatus of the embodiment described above, when the motor side voltage VH (power equipment side voltage) which is the voltage on the motor 11 side of the step-up / down converter 23 is higher than the target voltage VH *, the motor Step-down control of the step-up / step-down converter 23 for reducing the side voltage VH is executed. When such step-down control is executed, if the step-up / step-down converter 23 is normal, the power from the inverter 22 is stepped down and supplied to the battery 12, and the motor-side voltage VH decreases. Therefore, when the motor side voltage VHa after execution of the step-down control becomes lower than the motor side voltage VHb before execution of the step-down control, it can be determined that the step-up / step-down converter 23 is normal (steps S110 to S130). When the motor side voltage VHa after execution of the control is not lower than the motor side voltage VHb before execution of the step-down control, and current is flowing through the battery 12 during the execution of the step-down control, the step-up / down converter 23 is normal. It can be determined that an abnormality has occurred in voltage sensor 35 (steps S110, S150, and S160), and motor side voltage VHa after execution of step-down control does not become lower than motor side voltage VHb before execution of step-down control. In addition, when current is not flowing through the battery during the step-down control, the buck-boost converter The transistor Tr1 of the motor 23 can be determined off failure has occurred (step S110, S150 and S170). Thereby, it is possible to more appropriately determine whether or not the step-down control of the step-up / down converter 23 can be executed.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the battery 12 capable of exchanging electric power with the motor 11 as a power device, and the step-up / down converter 23 that converts voltage between the motor 11 correspond to the “step-up / down converter”. The voltage sensor 35 for detecting the motor side voltage VH, which is the voltage on the motor 11 side, corresponds to a “voltage sensor”, and controls the step-up / down converter 23 so that the motor side voltage VH becomes the target voltage VH * and the motor side When the voltage VH is higher than the target voltage VH *, the electronic control unit 40 that performs step-down control of the step-up / step-down converter 23 for reducing the motor-side voltage VH corresponds to “control means”. The electronic control unit 40 that executes the routine corresponds to “abnormality determination means”. The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  INDUSTRIAL APPLICABILITY The present invention can be used in the manufacturing industry of a power control device including a buck-boost converter that converts a voltage between a battery and a power device.

  DESCRIPTION OF SYMBOLS 10 Electric vehicle, 11 Motor, 12 Battery, 16 Differential gear, 18a, 18b Drive wheel, 22 Inverter, 23 Buck-boost converter, 31, 32 Smoothing capacitor, 33 Resistance element, 34, 35 Voltage sensor, 40 Electronic control unit, 54 Accelerator pedal, 55 Accelerator pedal position sensor, 58 Vehicle speed sensor, D1, D2 diode, Tr1, Tr2 transistor.

Claims (1)

A battery capable of exchanging power with a power device, a buck-boost converter that converts a voltage between the battery and the power device, and a power device-side voltage that is a voltage on the power device side of the buck-boost converter And a voltage sensor that controls the step-up / down converter so that the power equipment side voltage becomes a target voltage, and when the power equipment side voltage is higher than the target voltage, the power equipment side voltage A power control device comprising control means for performing step-down control of the pressure converter,
When the power device side voltage after execution of the step-down control is lower than the power device side voltage before execution of the step-down control, it is determined that the buck-boost converter is normal, and after the step-down control is executed When the power device side voltage is not lower than the power device side voltage before execution of the step-down control, and the charging current is flowing through the battery during the step-down control, the buck-boost converter is normal. It is determined that an abnormality has occurred in the voltage sensor, and the power device side voltage after execution of the step-down control is not lower than the power device side voltage before execution of the step-down control and the step-down control is executed. further comprising an abnormality judging means for determining that abnormality occurs in the buck-boost converter when the charging current to the battery has not been flowing in The power control device according to symptoms.