JP2008007003A - Control device for hybrid vehicle - Google Patents

Abstract

A hybrid vehicle is reliably switched from a stopped state to a driving state.
A hybrid vehicle includes a high voltage battery that serves as a power source for a motor generator and a low voltage battery that serves as a power source for a starter motor and accessories, and the high voltage battery and the low voltage battery are connected via a converter. Is done. When the ignition switch is operated to the off side in order to switch the hybrid vehicle from the driving state to the stop state, the converter is switched to the operating state until the voltage of the low-voltage battery reaches the end-time voltage, and the electric power supplied from the high-voltage battery The low voltage battery is charged. As a result, the power of the low-voltage battery can be secured in preparation for the driving state of the vehicle, so that sufficient power is supplied to the starter motor and auxiliary equipment when the ignition switch is operated again. The vehicle can be quickly and reliably switched from the stopped state to the driving state.
[Selection] Figure 2

Description

  The present invention relates to a control apparatus for a hybrid vehicle that supplies power from a high voltage source to a low voltage source via a converter.

  Hybrid vehicles that use an engine and an electric motor as drive sources include a high-voltage battery (high voltage source) that supplies power to the electric motor, and a low-voltage battery (low voltage source) that supplies power to the starter motor and various accessories. ) And are installed. Further, a converter is provided between the high voltage battery and the low voltage battery, and power is supplied from the high voltage battery to the low voltage battery via this converter.

  By the way, if the ignition switch is operated to the off side under the condition that the remaining capacity of the low voltage battery is reduced, the power supplied to the starter motor is insufficient even if the ignition switch is operated to the on side again. This may make it difficult to start the engine. In order to avoid such a situation, when the remaining capacity of the low voltage battery falls below a predetermined value, the low voltage battery is always controlled to be almost fully charged by operating the converter and charging the low voltage battery. It can be considered. However, controlling the low-voltage battery in a state that is almost fully charged at all times changes a part of the electric energy to heat energy, which causes a decrease in the energy efficiency of the hybrid vehicle.

In addition, in order to start the engine reliably, a control device is proposed in which a low-voltage battery is charged before the starter motor is driven, as shown in Patent Document 1. In this control device, when it is determined that the remaining capacity of the low-voltage battery falls below a predetermined value when the ignition switch is operated to the on side, the converter is switched to the operating state before driving the starter motor. The low voltage battery is charged by the electric power supplied from the high voltage battery.
JP 2001-320807 A

  However, since the control device described in Patent Document 1 is configured to drive the starter motor after charging the low-voltage battery, the engine is started even in a situation where the engine should be started immediately. It was difficult. In addition, depending on the type of high-voltage battery, the voltage may drop significantly at extremely low temperatures, making it difficult to charge the low-voltage battery from the high-voltage battery, and securing the power necessary for starting the engine. May become difficult.

  An object of the present invention is to quickly and surely switch a hybrid vehicle to a driving state by outputting sufficient electric power from a low voltage source when an ignition switch is operated to the on side.

  The hybrid vehicle control device of the present invention is a hybrid vehicle control device including a high voltage source and a low voltage source, and is provided between the high voltage source and the low voltage source. The converter that supplies power to the low voltage source, and when the vehicle is switched to a stop state by operating an ignition switch, if the voltage of the low voltage source falls below a predetermined value, the converter is kept in an operating state to maintain the high voltage Converter control means for supplying power from a voltage source to the low voltage source.

  The hybrid vehicle control device according to the present invention includes a start motor that starts and rotates an engine with electric power from the low voltage source, and the converter control means starts from the high voltage source to the low voltage source until a predetermined voltage is reached. By supplying electric power to the engine, the electric power required at the time of starting the engine is ensured.

  The hybrid vehicle control device of the present invention has a starter motor for starting and rotating the engine with electric power from the low voltage source, and the converter control means is connected to the low voltage source from the high voltage source until a predetermined charging time elapses. By supplying electric power to the voltage source, the electric power required when starting the engine is secured.

  The control apparatus for a hybrid vehicle according to the present invention is characterized in that the converter control means sets a charging time based on the voltage of the low voltage source when the ignition switch is operated.

  According to the present invention, when the voltage of the low voltage source falls below a predetermined value when the vehicle is switched from the driving state to the stop state, the converter is kept in the operating state and power is supplied from the high voltage source to the low voltage source. Thus, it is possible to secure the power of the low voltage source in preparation for switching to the operating state. As a result, when the vehicle is switched to the driving state, sufficient electric power can be supplied to the starter motor, auxiliary machinery, etc., and the vehicle can be switched from the stopped state to the driving state quickly and reliably. Become.

  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 12 as drive sources. The power output from the engine 11 and the motor generator 12 is transmitted to the shift output shaft 15 via the torque converter 13 and the speed change mechanism 14 and then to each drive wheel via a differential 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, the deceleration energy and surplus power can be converted into electric energy and recovered.

  The motor generator 12 includes a stator 20 fixed to a transmission case (not shown) and a rotor 22 connected to a crankshaft 21 of the engine 11 and is a permanent magnet type synchronous motor that is driven and controlled by three-phase alternating current. ing. When driving the motor generator 12, a direct current output from a high voltage battery (for example, a lithium ion battery) 23 that is a high voltage source is converted into an alternating current by an inverter 25 connected via a battery relay 24. It has been converted. Then, by controlling the current value and frequency of the alternating current using the inverter 25, it is possible to control the motor torque and the motor speed output from the motor generator 12.

  Further, a starter motor 26 as a starter motor is provided in the vicinity of the torque converter 13, and a pinion 27 provided in the starter motor 26 meshes with a ring gear 28 of the torque converter 13. The pinion 27 of the starter motor 26 is movable between a projecting position that meshes with the ring gear 28 and a retracted position that does not mesh with the starter motor 26, and the crankshaft 21 is driven by moving the pinion 27 to the projecting position and driving the starter motor 26. Can be started and rotated. Note that the illustrated starter motor 26 is a direct current motor that is driven and controlled by a direct current, and a direct current is supplied to the starter motor 26 from a low voltage battery (for example, a 12V lead storage battery) 29 that is a low voltage source.

  A high voltage battery 23 serving as a power source for the motor generator 12 and a low voltage battery 29 serving as a power source for the starter motor 26 are connected via a DC / DC converter (hereinafter referred to as a converter) 30. Since this converter 30 can generate a low voltage current from a high voltage current, power can be supplied from the high voltage battery 23 to the low voltage battery 29. The low-voltage battery 29 not only functions as a power source for the starter motor 26 but also supplies power to auxiliary devices 31 such as a headlight, tail lamp, turn signal, and blower, as well as an inverter 25 and a converter 30, which will be described later. Electric power is also supplied to each control unit and the like.

  In addition, a battery control unit 32 is connected to the high voltage battery 23, and the charge / discharge amount of the high voltage battery 23 is controlled by the battery control unit 32, and the remaining capacity SOC ( state of charge) is calculated. Further, the hybrid vehicle is provided with an engine control unit 33, and a control signal is output from the engine control unit 33 to a throttle valve, an injector, an igniter and the like. Further, a hybrid control unit 34 is provided in the hybrid vehicle, and a control signal is output from the hybrid control unit 34 to the inverter 25, the converter 30, the starter motor 26, the battery relay 24, and the like. These control units 32 to 34 include a CPU that calculates control signals and the like, and also includes a ROM that stores control programs, arithmetic expressions, map data, and the like, and a RAM that temporarily stores data. Note that the control units 32 to 34 are connected to each other via a communication network, and various information can be shared between the control units 32 to 34.

  The hybrid control unit 34 also includes an ignition switch 35 for switching the vehicle between a driving state and a stopped state, a voltage sensor 36 for detecting the voltage of the low voltage battery 29, an inhibitor switch for detecting the operating range of the select lever, and an accelerator. An accelerator pedal sensor that detects the depression state of the pedal, a brake pedal sensor that detects the depression state of the brake pedal, and the like are connected. The hybrid control unit 34 determines the vehicle state based on various information input from the control units 32 and 33, the ignition switch 35, various sensors, and the like, and controls the inverter 25, the engine control unit 33, and the battery control unit 32. Thus, the control signal is output and the motor generator 12, the engine 11, the high voltage battery 23, and the like are controlled in cooperation with each other.

  Next, vehicle stop control for switching the hybrid vehicle from the driving state to the stop state by operating the ignition switch 35 from the on side to the off side will be described. FIG. 2 is a timing chart showing the operating states of the converter 30 and the battery relay 24 and the voltage change of the low-voltage battery 29 accompanying the vehicle stop control.

  First, in an operation state in which the ignition switch 35 is operated to the ON side, not only the engine 11 and the motor generator 12 are controlled by the hybrid control unit 34, but also as converter control means as shown in FIG. The charge / discharge state of the low voltage battery 29 is controlled by the functioning hybrid control unit 34. That is, when it is determined by the hybrid control unit 34 that the voltage of the low voltage battery 29 (low voltage system voltage) has fallen below a predetermined lower limit voltage, the converter 30 is switched to the operating state (ON state), and the high voltage battery 23 Charging control for the low voltage battery 29 is started. On the other hand, when it is determined by the hybrid control unit 34 that the low-voltage system voltage has exceeded a predetermined upper limit voltage by charging, the converter 30 is switched to a stopped state (off state), and charging from the high voltage battery 23 to the low voltage battery 29 is performed. Control is stopped. In an operation state in which the ignition switch 35 is operated to the on side, the battery relay 24 is switched to a connected state (on state), and the high voltage battery 23 is connected to the inverter 25 or the converter via the battery relay 24. 30.

  Subsequently, in order to switch the hybrid vehicle from the driving state to the stopped state, when the ignition switch 35 is operated to the off side by the driver, the hybrid control unit 34 stops the engine 11 via the engine control unit 33, The converter 30 and the battery relay 24 are controlled to be turned on. When the hybrid control unit 34 determines whether or not the low voltage system voltage exceeds the end voltage required when the engine is restarted, and if it is determined that the low voltage system voltage has not reached the end voltage, the converter 30 and the battery relay 24 are kept on. On the other hand, when the hybrid control unit 34 determines that the low-voltage system voltage has reached the end-time voltage, the converter 30 and the battery relay 24 are switched to the off state.

  As described above, even when the ignition switch 35 is operated to the OFF side, if the low voltage battery 29 has not reached the predetermined end voltage, the converter until the low voltage battery 29 reaches the end voltage. 30 and the battery relay 24 are controlled to be in the ON state, so that it is possible to sufficiently secure the power of the low-voltage battery 29 in preparation for the restart of the engine 11. Thereby, when the ignition switch 35 is operated to the ON side, the engine 11 can be restarted quickly and reliably and the vehicle can be switched to the driving state.

  Hereinafter, the vehicle stop control described above will be described according to a flowchart. Here, FIG. 3 is a flowchart showing an execution procedure of the vehicle stop control. As shown in FIG. 3, in step S1, it is determined whether or not converter 30 and battery relay 24 are in an on state. When the converter 30 and the battery relay 24 are in the off state, the vehicle is already in the stopped state, and thus the routine is exited. On the other hand, when the converter 30 and the battery relay 24 are in the on state, the process proceeds to step S2 and the ignition is performed. It is determined whether or not the switch 35 is operated to the off side. If it is determined in step S2 that the ignition switch 35 is in the ON state, the vehicle 30 is in an operating state, and thus the process proceeds to step S3, where the low voltage system voltage is kept between the upper limit voltage and the lower limit voltage. Normal control is executed. On the other hand, if it is determined in step S2 that the ignition switch 35 is in the off state, the on-state of the converter 30 and the battery relay 24 is maintained so that the vehicle stop control is started. Charging control for the voltage battery 29 is executed.

  Then, it progresses to step S4 and it is determined whether the voltage of the low voltage battery 29 exceeds an end time voltage. If it is determined in step S4 that the low-voltage system voltage is lower than the end-time voltage, it is a state in which sufficient power is not secured for engine restart, and therefore, the high-voltage battery 23 to the low-voltage battery 29 Charging control is continued. When it is determined in step S4 that the low-voltage system voltage exceeds the end-time voltage, since sufficient power is secured for engine restart, the process proceeds to step S5, where converter 30 and battery The relay 24 is switched to the off state, and the vehicle is completely switched to the stopped state.

  In the above description, since the voltage of the low-voltage battery 29 does not exceed the end-time voltage in the normal control, the converter 30 and the battery relay 24 are immediately turned on when the ignition switch 35 is operated to the off side. Is controlling. On the other hand, in a hybrid vehicle in which the voltage of the low voltage battery 29 exceeds the end voltage in the normal control, after determining whether the voltage of the low voltage battery 29 is lower than the end voltage, the high voltage battery Needless to say, it may be determined whether or not to charge the low-voltage battery 29 from 23.

  The hybrid control unit 34 holds the converter 30 in the on state until the low-voltage system voltage reaches the end-time voltage after the ignition switch 35 is operated to the off side, but until a predetermined charging time elapses. The converter 30 may be controlled so as to be kept on. Further, the length of the charging time for holding converter 30 in the on state may be set based on the magnitude of the low-voltage system voltage when ignition switch 35 is operated to the off side.

  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 23 that supplies power to the motor generator 12 is not limited to a lithium ion battery, and may be a nickel metal hydride battery, a capacitor, or the like. Similarly, the low-voltage battery 29 that supplies power to the starter motor 26 is not limited to the lead-acid battery, and other types of batteries and capacitors may be used.

It is the schematic which shows the control apparatus of the hybrid vehicle which is one embodiment of this invention. It is a timing chart which shows the operating state of the converter and battery relay accompanying vehicle stop control, and the change state of the output voltage of a low voltage battery. It is a flowchart which shows the execution procedure of vehicle stop control.

Explanation of symbols

11 Engine 23 High voltage battery (High voltage source)
26 Starter motor (starting motor)
28 Low voltage battery (low voltage source)
30 DC / DC converter (converter)
34 Hybrid control unit (converter control means)
35 Ignition switch

Claims (4)

A control device for a hybrid vehicle comprising a high voltage source and a low voltage source,
A converter provided between the high voltage source and the low voltage source and supplying power from the high voltage source to the low voltage source;
When the vehicle is switched to a stop state by operating an ignition switch, if the voltage of the low voltage source falls below a predetermined value, power is supplied from the high voltage source to the low voltage source while keeping the converter in an operating state. A control apparatus for a hybrid vehicle, comprising: a converter control means. In the hybrid vehicle control device according to claim 1,
A starter motor for starting and rotating the engine with electric power from the low voltage source;
The control device for a hybrid vehicle, wherein the converter control means secures electric power required when starting the engine by supplying electric power from the high voltage source to the low voltage source until a predetermined voltage is reached. In the hybrid vehicle control device according to claim 1,
A starter motor for starting and rotating the engine with electric power from the low voltage source;
The converter control means secures electric power required at the time of starting the engine by supplying electric power from the high voltage source to the low voltage source until a predetermined charging time elapses. apparatus. In the hybrid vehicle control device according to claim 3,
The control device for a hybrid vehicle, wherein the converter control means sets a charging time based on a voltage of the low voltage source when an ignition switch is operated.

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