JP5076936B2 - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress charging to a secondary battery in completion of engine starting and protect the secondary battery effectively in a hybrid vehicle. <P>SOLUTION: A maximum permissible output power from the secondary battery is increased to a level above the reference output power by the engine starting. The output voltage of the secondary battery does not fall below a predetermined lower limit voltage, the difference between the maximum permissible output power from the secondary battery and the output instruction power from the secondary battery is changed. In performing limitation of the output power from the secondary battery in which the output power from the secondary battery is limited, the difference between the maximum permissible output power from the secondary battery and the output instruction power from the secondary battery is reduced by the completion of the engine starting, canceling out the limitation of the output power from the secondary battery so that the output instruction power from the secondary battery is not in a charging state. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a hybrid vehicle, and more particularly to control at engine start.

  A hybrid system for a vehicle travels by combining two types of power sources, an engine and a motor. A series hybrid system in which a generator is driven by the engine and a motor drives wheels by the generated power, and an engine and a motor There are a parallel hybrid system that can use two driving forces depending on the situation, and a series / parallel hybrid system that combines the features of both. Such a hybrid vehicle has a secondary battery that can be charged and discharged to drive the motor or motor generator, and stops the engine operation when the required power is low or the vehicle speed is low. Then, there is a battery that can run in an all-electric running mode in which only the power from the motor or motor generator is output to the drive shaft using the power of the secondary battery.

  In a hybrid vehicle including a parallel hybrid system, a power split device that uses a planetary gear device and divides engine power into power for driving the vehicle and drive power for the generator is often used. In this planetary gear type power split device, the engine can be rotated by a motor generator for driving the vehicle by fixing the rotation of some of the planetary gears. A method of starting the engine by a vehicle drive motor generator when starting the engine when shifting from the state to the engine running is used (for example, see Patent Document 1).

JP 2006-296183 A

  The secondary battery that supplies power to the motor generator can be used to reliably crank and start the engine even when the temperature of the secondary battery is low because the available power decreases due to an increase in internal resistance when the temperature drops. As described above, when the engine is started, output power expansion control is performed to increase the maximum allowable output power of the secondary battery beyond the reference allowable output power. On the other hand, in the secondary battery, control is performed to limit the output power by feeding back the output voltage by proportional integral control so that the output voltage does not fall below a predetermined lower limit voltage in order to prevent deterioration.

  When starting the engine, the maximum allowable output power of the secondary battery is expanded, and if a large amount of power is output from the secondary battery, the output voltage of the secondary battery decreases. Is controlled so as to reduce the output power so as not to fall below a predetermined lower limit voltage. When the start of the engine is completed, the output power expansion control of the secondary battery is canceled, and the maximum allowable output power from the secondary battery is reduced to the reference allowable output power.

However, since the control based on the output voltage uses proportional-integral control, there is a time delay in the amount of power reduction by feedback. Therefore, the output power expansion control of the secondary battery is released, the maximum allowable output even power is reduced, regardless such power reduction amount by the feedback to zero, power reduction by reducing the feedback of the maximum allowable output power In some cases, the output command power to the secondary battery may become negative due to overlap with the amount. When the output command power to the secondary battery becomes negative, the power from the motor generator flows in the charging direction of the secondary battery. And when this charging power is large, it may become an overcharge and the fall of the performance or deterioration of a secondary battery may be caused.

  An object of the present invention is to suppress the charging of the secondary battery when the engine start is completed in the hybrid vehicle and effectively protect the secondary battery.

The hybrid vehicle of the present invention includes an engine that drives the vehicle, a motor generator that is connected to the engine and drives the vehicle and starts the engine, a secondary battery that supplies electric power to the motor generator, and a secondary battery. And a controller that increases or decreases the output power. The controller increases the maximum allowable output power from the secondary battery by the start of engine start over the reference output power, and the secondary battery by the completion of engine start. The secondary battery maximum allowable output power increase / decrease means for reducing the maximum allowable output power from the reference battery to the reference output power, and the secondary battery output voltage and the predetermined voltage so that the output voltage of the secondary battery does not fall below a predetermined lower limit voltage . By proportional-integral control based on the difference from the lower limit voltage, the difference between the maximum allowable output power of the secondary battery and the output command power of the secondary battery is changed. Output power limiting means for limiting the output power of the secondary battery, and by reducing the difference between the maximum allowable output power of the secondary battery and the output command power of the secondary battery upon completion of engine start, Output power limit canceling means for canceling part or all of the output power.

In the hybrid vehicle of the present invention, the output power limit canceling means is also suitable for reducing the difference between the maximum allowable output power and the output command power of the secondary battery by the difference between the maximum allowable output power and the reference output power. it is, the output power limiting cancellation means, the maximum allowable output power and be reduced by limiting the power amount based on the integral term output power limiting means the difference between the output command power of the secondary battery, it is also preferable.

  The present invention has an effect that the secondary battery can be effectively protected by suppressing charging of the secondary battery when the engine start is completed in the hybrid vehicle.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the hybrid vehicle 10 of the present invention, an engine 11 that drives the hybrid vehicle 10, an output shaft 12 of the engine 11, and an output shaft 14 of a motor generator 15 are connected, and the output of the engine 11 and the output to the motor generator 15 are driven. A planetary gear 13 that is divided into an output to the shaft 18, a secondary battery 17 that supplies electric power to the motor generator 15 and stores electric power generated by the motor generator 15, and a DC output of the secondary battery 17 to the motor generator 15 And an inverter 16 that converts AC power generated by the motor generator 15 into DC power stored in the secondary battery 17 while converting the AC power into three-phase AC power. The planetary gear 13 includes a plurality of planetary gears and a brake for stopping some of the gears, and an operation mode for distributing the output of the engine 11 to the motor generator 15 and the drive shaft 18 by turning on and off the brake, and a motor A start mode for rotating the engine 11 can be switched by the output of the generator 15.

  A torque sensor 21 that measures the output torque of the engine 11 and a rotation speed sensor 22 that detects the rotation speed of the engine 11 are attached to the output shaft 12 of the engine 11. The engine 11 is provided with a misfire sensor 23 for detecting the combustion state in the cylinder inside the engine 11. The motor generator 15 is provided with a torque sensor 24 that detects output torque. The secondary battery 17 and the inverter 16 are connected by two power cables, and a voltage sensor 25 for measuring the output voltage of the secondary battery 17 is provided between the two power cables. A current sensor 26 for measuring a current is provided on the power line.

  The engine 11, the planetary gear 13, the inverter 16, and the secondary battery 17 are connected to the control unit 30 and configured to be controlled by commands from the control unit 30. Further, the torque sensors 21 and 24, the rotation speed sensor 22, the misfire sensor 23, the voltage sensor 25, and the current sensor 26 are each connected to the control unit 30, and the control unit 30 can acquire signal data of each sensor. Has been.

  The control unit 30 is a computer that includes a CPU that processes and calculates signals, a memory that is a storage device, and interfaces that interface each device and sensor.

  The start of the engine 11 when the hybrid vehicle 10 configured as described above starts the engine 11 and shifts to engine running from the all-electric running state will be described. 2A is a line showing a change in the maximum allowable output power from the secondary battery, a curve 42 shows the output command power of the secondary battery 17, and a curve 43 in FIG. 2B. 2 represents the output voltage of the secondary battery 17, and the curve 44 in FIG. 2C represents the time variation of the power difference between the maximum allowable output power of the secondary battery 17 and the output command power of the secondary battery 17. Yes.

As shown in FIG. 2 (a), the time t ₁ before the engine 11 is started, the hybrid vehicle 10 is traveling by only the output of the motor generator 15, a point of the polygonal line 41 in FIGS. 2 (a) 2 and the point b, the maximum allowable output power of the secondary battery 17 is a constant value at the reference output power, and the output power from the secondary battery 17 is the point of the curve 42 in FIG. The power is lower than the allowable maximum output power as indicated by f to g.

At time t ₁ , a start command for the engine 11 is output from the control unit 30. This is because, for example, the driver has stepped on the accelerator, so that only the output of the motor generator 15 is insufficient to accelerate the hybrid vehicle 10, so the engine 11 is started and accelerated together with the output from the engine 11. Or when the remaining capacity of the secondary battery 17 is reduced, and it becomes necessary to start the engine 11 and charge the secondary battery 17.

  When an engine start command is output from the control unit 30, the command signal increases the maximum allowable output power of the secondary battery 17 from the point b to the point c of the broken line 41 in FIG. . The magnitude of the electric power to be enlarged is ΔW. Then, the control unit 30 changes the braking state of the planetary gear 13 to a start mode in which the engine 11 is rotated by the output of the motor generator 15, and as shown by a point g of the curve 42 in FIG. Start cranking and start engine. When the cranking of the engine 11 is started, the control unit 30 uses the current sensor 26 and the voltage sensor 25 of the secondary battery 17 as shown in the point g to the point h of the curve 42 in FIG. The output command power from the secondary battery 17 to the motor generator 15 is increased to the maximum allowable output power while monitoring the output power from the engine 11, and the engine 11 is started. At this time, when the output command power from the secondary battery increases, the actual output power from the secondary battery 17 also increases, as shown from the point m to the point l of the curve 43 in FIG. The output voltage of the secondary battery 17 gradually decreases. However, since the output voltage of the secondary battery 17 has not decreased to the lower limit voltage, the output command power of the secondary battery 17 is the maximum allowable power as shown from the point h to the point i in FIG. The power is the same.

Then, as shown in the l point in FIG. 2 (b), the time since the output voltage of the t ₂ in the secondary battery 17 falls below the lower limit voltage, the voltage of the secondary battery 17 to output command power of the secondary battery 17 Start to be limited by feedback. Since the voltage feedback is proportional-integral control based on the signal of the voltage sensor 25, the maximum allowable output power of the secondary battery 17 with time is obtained as shown from the point s to the point t of the curve 44 in FIG. The difference from the output command power, that is, the amount of reduction from the maximum allowable output power increases, and the output command power of the secondary battery gradually decreases. The output command power of the secondary battery 17 is reduced by reducing the output current command from the secondary battery 17 to the inverter 16. Further, the control unit 30 monitors the output current and output voltage of the secondary battery 17 with the current sensor 26 and the voltage sensor 25. During this time, the output voltage of the secondary battery 17 is maintained at a substantially lower limit voltage, and the cranking and starting operations of the engine 11 by the motor generator 15 are continued.

  As shown from the point s to the point t of the curve 44 in FIG. 2C, while the cranking and starting operation of the engine 11 by the motor generator 15 continues, the output voltage of the secondary battery 17 is lower than the lower limit voltage. Since the output command power from the secondary battery 17 to the motor generator 15 is limited by feedback control that does not occur, the difference between the maximum allowable output power and the output command power of the secondary battery increases with time, As shown from the point i to the point j of the curve 42 in FIG. 2A, the output command power of the secondary battery 17 is in a state of being greatly reduced from the maximum allowable output power.

During cranking of the engine 11, the control unit 30 monitors the operating state of the engine 11 by the rotation speed sensor 22, the torque sensor 21, and the misfire sensor 23. Then, for example, the control unit 30 indicates that the signals of the sensors 21, 22, and 23 indicate that the engine 11 has a rotational speed equal to or higher than a predetermined speed, the engine 11 output torque is equal to or higher than a predetermined torque, and the engine 11 is in a misfire state. If it indicates a normal combustion state, it is determined that the engine 11 has been started. In the present embodiment, at time t _3, the control unit 30 determines that the engine 11 is started completed.

  As shown from the point d to the point e in FIG. 2A, when the control unit 30 determines that the start of the engine 11 has been completed, the control unit 30 cancels the power expansion control of the secondary battery 17 and the maximum of the secondary battery 17 is reached. The allowable output power is reduced by the power expansion amount ΔW, and the output power from the secondary battery is limited to the initial reference output power.

At time t ₃ , the output command power of the secondary battery 17 is lower than the reference output power, as indicated by a point j in FIG. The maximum allowable output power of the secondary battery 17 is reduced by the power expansion amount ΔW, and the difference between the maximum allowable output power and the output command power of the secondary battery 17 is indicated by a point t on the curve 44 in FIG. In the case of being large, the maximum allowable output power that becomes the reference of the output command power of the secondary battery 17 is reduced by canceling the power expansion control, so the output command power of the secondary battery 17 is the point of FIG. The power drops to j ′ and the charging power flows to the secondary battery 17. However, as shown from the point t to the point u of the curve 44 in FIG. 2C, when the start of the engine 11 is completed, the control unit 30 determines the difference between the maximum allowable output power and the output command power of the secondary battery, that is, A command for reducing the limit amount of the output power of the secondary battery 17 by the power expansion amount ΔW is output.

  As a result, as indicated by points j ′ to j of the curve 42 in FIG. 2A, the reduction of the power expansion amount ΔW due to the cancellation of the power expansion control, the maximum allowable output power, and the output command power of the secondary battery 17 By offsetting the difference from ΔW, the limit of the output power of the secondary battery 17 is canceled, and the output command power of the secondary battery 17 hardly moves from the position of the point j. Further, the output command power to the secondary battery does not become the charge command power to the secondary battery 17, and the secondary battery 17 can be protected from overcharging. Further, since the output command power of the secondary battery 17 hardly fluctuates, fluctuations in output power from the secondary battery can be suppressed.

  As described above, the present embodiment has an effect that the hybrid battery 10 can effectively protect the secondary battery 17 by suppressing the charging of the secondary battery 17 when the engine 11 is started. Play.

  In the present embodiment, it has been described that the difference between the maximum allowable output power and the output command power of the secondary battery 17 is reduced by the amount of power expansion ΔW of the secondary battery 17 when the engine start is completed. If the output command power does not charge the secondary battery 17, the reduction amount is not limited to ΔW, but may be changed depending on the driving state of the hybrid vehicle 10, and is reduced by an integral term in the proportional integral control. A part of the limitation on the output power from the secondary battery may be offset by reducing the power.

It is a figure which shows the structure of the hybrid vehicle in embodiment of this invention. In the hybrid vehicle of this invention, it is a graph which shows the output electric power of secondary battery with respect to time, output command power, output voltage, and the difference of maximum permissible output power and output command power.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 11 Engine, 12 Output shaft, 13 Planetary gear, 14 Output shaft, 15 Motor generator, 16 Inverter, 17 Secondary battery, 18 Drive shaft, 21, 24 Torque sensor, 22 Speed sensor, 23 Misfire sensor, 25 Voltage sensor, 26 Current sensor, 30 Control unit, ΔW Power expansion amount.

Claims (3)

An engine for driving a vehicle, a motor generator connected to the engine for driving the vehicle and starting the engine, a secondary battery for supplying electric power to the motor generator, and a controller for increasing or decreasing output power from the secondary battery And a hybrid vehicle including:
The control unit
The maximum allowable output power from the secondary battery is increased from the reference output power when the engine starts, and the maximum allowable output power from the secondary battery is reduced to the reference output power when the engine is completed. Means,
The maximum allowable output power of the secondary battery and the secondary battery are controlled by proportional integral control based on the difference between the output voltage of the secondary battery and the predetermined lower limit voltage so that the output voltage of the secondary battery does not fall below the predetermined lower limit voltage. Output power limiting means for limiting the output power from the secondary battery by changing the difference from the output command power of
Output power limit canceling means for canceling a part or all of the limit of the output power from the secondary battery by reducing the difference between the maximum allowable output power of the secondary battery and the output command power of the secondary battery upon completion of engine start And having
A hybrid vehicle characterized by The hybrid vehicle according to claim 1,
The output power limit canceling means reduces the difference between the maximum allowable output power and the output command power of the secondary battery by the difference between the maximum allowable output power and the reference output power;
A hybrid vehicle characterized by A hybrid vehicle according to claim 1 or 2 ,
Output power limiting canceling means, be reduced by limiting the power amount based a difference between the output command power maximum allowable output power and the secondary battery to the integral term output power limiting means,
A hybrid vehicle characterized by

Images