JP2008168754A - Control device of hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hybrid vehicle for travelling an enough distance by using an engine even in the case of failure of a motor system. <P>SOLUTION: A hybrid vehicle includes a high-voltage battery 19 supplying electric power to a motor generator 12, and a low-voltage battery 21 supplying electric power to control units 30-32, etc. The butteries 19, 21 are connected to each other through a converter 22. In the case of an occurrence of failure of the generator 12 or an inverter 17, etc., a hybrid control unit 32 operates the converter 22 to make the electric power in the battery 19 charge to the battery 21 until the remaining capacity of the battery 19 reaches a prescribed lower limit value in response to a vehicle state. Thereby, the vehicle supplies enough electric power to the control units 30-32 for keeping operation state thereof normal, and can travel an enough distance even in the case of emergency travelling by using solely an engine 11. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a control device for a hybrid vehicle including an engine and an electric motor as drive sources.

  Hybrid vehicles that use an engine and an electric motor as a drive source include a series system in which the engine is driven as a drive source for power generation while the engine is driven as a drive source for power generation. There is a parallel system in which an electric motor is driven as a main drive source while an electric motor is driven auxiliary when starting or accelerating. In addition, a series / parallel system has been developed in which one or both of the engine and the electric motor are driven in accordance with the running situation by combining the series system and the parallel system.

In addition, a high voltage battery is connected to an electric motor (for example, a permanent magnet type synchronous motor) mounted on a hybrid vehicle via an inverter that generates a three-phase alternating current, and the torque and rotation speed of the electric motor are controlled by the inverter. I have control. By the way, when an electric motor or an inverter fails and cannot be controlled normally, it is important to stop the electric motor promptly and protect the inverter. Therefore, when a failure occurs in the electric motor or the inverter, the high voltage battery and the inverter are disconnected after the rotation speed of the electric motor decreases and the back electromotive voltage generated from the electric motor falls below a predetermined value. A control device has been proposed (see, for example, Patent Document 1). As a result, the electric motor can be stopped and the inverter can be protected from the counter electromotive voltage of the electric motor.
JP 2004-159401 A

  By the way, when an electric motor or an inverter breaks down, it is important not only to protect the inverter but also to move the vehicle while ensuring a minimum traveling performance. Since the hybrid vehicle includes an engine and an electric motor as drive sources, even if a failure occurs in the electric motor or the inverter, it is possible to ensure the minimum traveling performance using the engine. However, even when running using only the engine, it is necessary to supply power to various control units and engine accessories from a low-voltage battery having a lower capacity than the high-voltage battery. It has been difficult to sufficiently extend the mileage with only the electric power stored in the vehicle.

  An object of the present invention is to provide a hybrid vehicle that can travel a sufficient distance even when a motor system fails.

  A hybrid vehicle control device according to the present invention is a hybrid vehicle control device including an engine and an electric motor as drive sources, and a low-voltage power source that supplies power to a vehicle control system, and a high-voltage that supplies power to the electric motor. A voltage source, motor failure detecting means for detecting a fault condition of the motor system, a converter provided between the high voltage power source and the low voltage power source and supplying power from the high voltage power source to the low voltage power source; And a fail-safe means for operating the converter in accordance with a vehicle state until a storage amount of the high-voltage power source reaches a predetermined lower limit value when a failure state of the motor system is detected.

  The hybrid vehicle control device according to the present invention is characterized in that, when a failure state of the motor system is detected, the fail-safe means cuts off power supply from the high-voltage power supply to devices other than the converter.

  The control apparatus for a hybrid vehicle according to the present invention is characterized by comprising notifying means for notifying a driver of a failure state when a failure state of the motor system is detected.

  According to the present invention, when the motor system fails, the converter is operated in accordance with the vehicle state until the storage amount of the high voltage power source reaches the predetermined lower limit value, so that power is supplied from the high voltage power source to the low voltage power source. Therefore, it is possible to sufficiently secure the electric power supplied from the low voltage power source to the vehicle control system. Thereby, since the operating state of the vehicle control system can be kept normal, the travelable distance can be extended even when traveling using only the engine.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing a control apparatus for a hybrid vehicle according to an embodiment of the present invention. As shown in FIG. 1, the power unit 10 mounted on the hybrid vehicle is provided with an engine 11 and a motor generator (electric motor) 12 as drive sources. The power output from the engine 11 and the motor generator 12 is transmitted to each drive wheel via a torque converter 13 and a transmission mechanism (not shown). The illustrated power unit 10 is a parallel power unit, and the engine 11 is driven as a main driving source for traveling, while the motor generator 12 is driven as an auxiliary driving source at the time of start or acceleration. Further, when the motor generator 12 is driven to generate power during deceleration or steady running, kinetic energy can be converted into electric energy and recovered.

  The motor generator 12 includes a stator 14 fixed to a housing (not shown) and a rotor 16 connected to the crankshaft 15 of the engine 11 and is a permanent magnet type synchronous motor that is driven and controlled by three-phase AC. Yes. The motor generator 12 is connected to a high voltage battery 19 (for example, a lithium ion battery) as a high voltage power source via an inverter 17 and a battery relay 18. Then, the direct current from the high voltage battery 19 is converted into an alternating current through the inverter 17 and the current value and frequency of the alternating current are controlled through the inverter 17, so that the torque and the rotational speed of the motor generator 12 are controlled. It becomes possible to control. Further, a high voltage system device 20 is connected to the high voltage battery 19 via a battery relay 18, and an electric air conditioner or the like which is the high voltage system device 20 is driven by electric power from the high voltage battery 19. Yes.

  A low voltage battery 21 (for example, a 12V lead storage battery) as a low voltage power source is connected to a high voltage battery 19 via a DC / DC converter 22. Since this converter 22 can generate a low voltage current from a high voltage current, power can be supplied from the high voltage battery 19 to the low voltage battery 21. The low-voltage battery 21 functions as a power source for the low-voltage equipment 23 such as a headlight, tail lamp, turn signal, blower, and engine auxiliary equipment, and also includes an inverter 17, a converter 22, control units 30 to 32 described later, and the like. It also functions as a power source. In this way, the low-voltage equipment 23 and the control units 30 to 32 that function as the vehicle control system are operated by the electric power from the low-voltage battery 21.

  In addition, a battery control unit 30 is connected to the high voltage battery 19, and charging / discharging of the high voltage battery 19 is controlled by the battery control unit 30, and a remaining capacity SOC is calculated based on voltage, current, cell temperature, and the like. Is done. An engine control unit 31 is provided, and a control signal is output from the engine control unit 31 to a throttle valve, an injector, an igniter, and the like. Further, a hybrid control unit 32 is provided, and a control signal is output from the hybrid control unit 32 to the inverter 17, the converter 22, the battery relay 18, and the like. These control units 30 to 32 include a CPU that calculates control signals and the like, and also includes a ROM that stores a control program, an arithmetic expression, map data, and a RAM that temporarily stores data. The control units 30 to 32 are connected to each other via a communication network, and various types of information are shared between the control units 30 to 32.

  Further, the hybrid control unit 32 includes an ignition switch 33 that switches the vehicle between a driving state and a stopped state, a current sensor 34 that detects a current value on the inverter input side, a voltage sensor 35 that detects a voltage value on the inverter input side, an inverter Current sensors 36 to 38 for detecting the current value on the output side, a voltage sensor 39 for detecting the voltage value of the low voltage battery 21, a warning light 40 as a notification means for notifying the driver of the vehicle malfunction state, and depression of the accelerator pedal An accelerator pedal sensor (not shown) for detecting, a brake pedal sensor (not shown) for detecting depression of the brake pedal, and the like are connected. The hybrid control unit 32 determines the vehicle state based on various information input from the various control units 30 and 31, the switch 33, the sensors 34 to 39, and the inverter 17, the engine control unit 31, and the battery control unit 30. The control signal is output to the motor generator 12, the engine 11, the high voltage battery 19, and the like while controlling each other.

  Next, failsafe control executed when a failure occurs in the motor system will be described. Here, FIG. 2 is an explanatory diagram showing the remaining capacity change of the high-voltage battery 19 and the voltage change of the low-voltage battery 21, and FIG. 2 shows the change in the situation where the fail-safe control is executed. . The motor system means a system constituted by the motor generator 12, the inverter 17, current sensors 34, 36 to 38, voltage sensors 35, 39, energization lines, and the like.

  First, as shown in FIG. 1, the hybrid control unit 32 that functions as a motor failure detection unit monitors current values and voltage values output from the current sensors 34 and 36 to 38 and the voltage sensors 35 and 39. Based on these current values and voltage values, it is determined whether or not the motor system is in a failure state. For example, the current values Iu, Iv, and Iw supplied from the inverter 17 to the motor generator 12 have substantially the same peak values at normal times, and therefore the individual peak values detected by the current sensors 36 to 38 are different. When the value is indicated, it is determined that a disconnection has occurred in the stator coil or the energization line. When such a failure state of the motor system is detected, the hybrid control unit 32 functioning as a fail-safe means detects only the engine 11 from the normal control that controls one or both of the engine 11 and the motor generator 12 as a drive source. The control method is switched to fail-safe control in which the power source is controlled as a drive source.

  When switching from normal control to fail-safe control, the battery relay 18 is switched to electrically disconnect the inverter 17 and the high-voltage battery 19, thereby cutting off the power supply and stopping the drive control of the motor generator 12. Subsequently, the hybrid control unit 32 switches the control method from normal control to fail-safe control by controlling the driving state of the engine 11 in accordance with the driver's operation status and the vehicle driving status, so that the minimum driving performance is achieved. To ensure. If an excessively induced voltage is generated in motor generator 12 that rotates at high speed, inverter 17 and high voltage battery 19 may be disconnected after the rotational speed of motor generator 12 is reduced.

  Even in fail-safe control using only the engine 11 as a drive source, it is necessary to supply power from the low-voltage battery 21 to various auxiliary devices and various control units 30 to 32. In order to ensure traveling performance, it is necessary to avoid power depletion of the low voltage battery 21. Therefore, as shown in FIG. 2, in the fail-safe control, when the hybrid control unit 32 determines that the low-voltage battery 21 is below the predetermined voltage lower limit value, the low-voltage battery 21 reaches the predetermined voltage upper limit value. The converter 22 is switched to the operating state (ON state), and charging control from the high voltage battery 19 to the low voltage battery 21 is executed. Further, in order to prevent overdischarge and protect the high voltage battery 19, the hybrid control unit 32 protects the high voltage battery 19 when the remaining capacity (charged amount) SOC of the high voltage battery 19 reaches a predetermined SOC lower limit value (predetermined lower limit value). In other words, the converter 22 is switched to a stopped state (off state) to stop the charging control for the low voltage battery 21.

  As described above, the converter 22 is operated according to the vehicle state until the remaining capacity SOC of the high voltage battery 19 reaches the predetermined lower limit value, so that the power from the high voltage battery 19 is charged into the low voltage battery 21. Thus, power can be supplied from the low-voltage battery 21 to the various control units 30 to 32 and various auxiliary machines for a long time. Thereby, even if it is a case where the fail safe control which makes it drive | work only using the engine 11 is performed, the operating state of various control units 30-32, engine auxiliary machines, etc. can be maintained normally over a long time. Therefore, the vehicle can be moved to a safe place with a sufficient travelable distance, and the safety of the hybrid vehicle can be improved. Moreover, since the converter 22 is controlled so that the remaining capacity SOC of the high voltage battery 19 does not fall below a predetermined lower limit value, the high voltage battery 19 that may be deteriorated by overdischarge is reliably protected. Is possible.

  In fail-safe control, the hybrid control unit 32 disconnects the inverter 17 and the high-voltage system device 20 from the high-voltage battery 19 and changes the operating state of the battery relay 18 so that only the converter 22 is connected to the high-voltage battery 19. Switching control is performed. That is, since the power consumption of the high-voltage battery 19 is suppressed by disconnecting the devices other than the converter 22 from the high-voltage battery 19, it is possible to secure sufficient power for charging the low-voltage battery 21. It is possible to extend the travelable distance in fail-safe control. Further, at the time of fail-safe control, the warning lamp 40 is turned on by a control signal from the hybrid control unit 32 to notify the driver of the motor system failure state.

  Hereinafter, the above-described converter switching control will be described with reference to a flowchart. Here, FIG. 3 is a flowchart showing the execution procedure of the converter switching control. As shown in FIG. 3, in step S1, it is determined whether or not the ignition switch 33 is in an on state. When it is determined that the ignition switch 33 is in the off state, the process proceeds to step S2, and the converter 22 is switched to the off state. On the other hand, if it is determined in step S1 that the ignition switch 33 is in the on state, it is determined in step S3 whether or not the operating condition of the converter 22 is satisfied. When the operating condition of the converter 22 is not satisfied, such as when the voltage of the low voltage battery 21 is sufficiently secured, the process proceeds to step S2 and the converter 22 is switched to the off state, while the low voltage battery 21 When the operating condition of the converter 22 is satisfied, such as when the voltage is lowered, the process proceeds to step S4, and it is determined whether or not a failure has occurred in the motor system.

  If it is determined in step S4 that the motor system has failed, the process proceeds to step S5, and it is determined whether or not the remaining capacity SOC of the high-voltage battery 19 exceeds a predetermined lower limit value. If it is determined in step S5 that the remaining capacity SOC exceeds the lower limit value, it is possible to supply power from the high voltage battery 19 to the low voltage battery 21, so the process proceeds to step S6, where the converter 22 Is switched on. On the other hand, when it is determined in step S5 that the remaining capacity SOC is lower than the lower limit value, the process proceeds to step S2 to protect the high voltage battery 19 from overdischarge, and the converter 22 is switched to the OFF state. If it is determined in step S3 that the operating condition of the converter 22 is satisfied and it is determined in step S4 that the motor system has not failed, the process proceeds to step S6, and the converter 22 is switched on. .

  Thus, the converter 22 is operated to charge the low voltage battery 21 from the high voltage battery 19 until the remaining capacity SOC of the high voltage battery 19 reaches a predetermined lower limit value. Electric power can be supplied to the control units 30 to 32 and various auxiliary machines, and a travelable distance in fail-safe control can be sufficiently secured. In addition, when the remaining capacity SOC of the high voltage battery 19 reaches the lower limit value, the converter 22 is switched to the stop state, so that overdischarge can be avoided and the high voltage battery 19 can be protected. .

  It goes without saying that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. For example, the high voltage battery 19 that supplies power to the motor generator 12 is not limited to a lithium ion battery, and may be a capacitor or another type of battery. Similarly, the low voltage battery 21 is not limited to a lead storage battery, and a capacitor or other type of battery can be used.

  In the above description, the operation of the converter 22 is permitted until the remaining capacity SOC of the high voltage battery 19 reaches a predetermined lower limit value. However, the voltage value of the high voltage battery 19 is set to the predetermined lower limit value. Until it reaches, the operation of the converter 22 may be permitted. Furthermore, the warning lamp 40 is lit to notify the driver of the motor system failure state, but the warning lamp 40 is not limited to the warning lamp 40, and a warning buzzer may be used as a notification means.

  Further, in the illustrated case, the control device of the present invention is applied to a parallel type hybrid vehicle, but the present invention is not limited to this, and the control device of the present invention is applied to a series / parallel type hybrid vehicle. It is also possible to apply.

It is the schematic which shows the control apparatus of the hybrid vehicle which is one embodiment of this invention. It is explanatory drawing which shows the remaining capacity change of a high voltage battery, and the voltage change of a low voltage battery. It is a flowchart which shows the execution procedure of converter switching control.

Explanation of symbols

11 Engine 12 Motor generator (electric motor, motor system)
17 Inverter (motor system)
19 High voltage battery (high voltage power supply)
21 Low voltage battery (low voltage power supply)
22 DC / DC converter (converter)
23 Low-pressure equipment (vehicle control system)
30 Battery control unit (vehicle control system)
31 Engine control unit (vehicle control system)
32 Hybrid control unit (motor failure detection means, fail-safe means)
34 Current sensor (motor system)
35 Voltage sensor (motor system)
36-38 Current sensor (motor system)
39 Voltage sensor (motor system)
40 Warning light (notification means)

Claims (3)

A control device for a hybrid vehicle including an engine and an electric motor as drive sources,
A low voltage power supply for supplying power to the vehicle control system;
A high voltage power supply for supplying power to the electric motor;
Motor failure detection means for detecting a failure state of the motor system;
A converter provided between the high-voltage power supply and the low-voltage power supply and supplying power from the high-voltage power supply to the low-voltage power supply;
And a fail-safe means for operating the converter in accordance with a vehicle state until a storage amount of the high-voltage power source reaches a predetermined lower limit when a failure state of the motor system is detected. Control device. In the hybrid vehicle control device according to claim 1,
The hybrid vehicle control device according to claim 1, wherein when a failure state of the motor system is detected, the fail-safe means cuts off power supply from the high-voltage power supply to devices other than the converter. In the hybrid vehicle control device according to claim 1,
A control device for a hybrid vehicle, comprising notification means for notifying a driver of a failure state when a failure state of the motor system is detected.

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