JP2009023496A - Regenerative control device and hybrid car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of such a wavy phenomenon that a vehicle speed is increased as regenerative torque is reduced if the rotating speed of an internal combustion engine is decreased due to regenerative braking when braking by a regenerative device when a vehicle travels down a slope in an idle state, and accordingly, the regenerative torque is increased, and then, the regenerative torque is reduced. <P>SOLUTION: When regenerative braking is started, and a speed of a car or the rotating speed of an internal combustion engine is lowered, and regenerative torque reaches a low limit limiter, the regenerative torque is suppressed from being increased any more. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a regenerative control device that applies braking to a vehicle by a regenerative braking force by a generator. The present invention is used for regenerative torque control in a hybrid vehicle, but can also be used for regenerative torque control in other vehicle braking devices that use a generator such as a retarder for braking.

  The hybrid vehicle includes an internal combustion engine and a motor generator, and assists driving by using the motor generator as an electric motor in response to driver's accelerator control and brake control. Used as a device. A mode in which this motor generator is used as a generator is called a regeneration mode, and the regenerated energy is converted into electricity and stored in a battery. Since the regenerated electric energy is used for driving assistance using a motor generator as a motor, energy can be effectively used, and effects such as improvement of fuel consumption and reduction of exhaust gas can be obtained. Therefore, hybrid vehicles are becoming widespread.

JP 2003-062111 A

  For example, when driving on a downhill, when the driver releases the accelerator pedal, the regenerative mode is automatically entered, and the motor generator operates as a generator and a braking force is generated in the vehicle by the regenerative torque.

  At this time, in the conventional regenerative control, if the engine reaches a low rotation range due to regenerative operation and continues to regenerate further, the speed is further reduced to reach the limit where engine stop occurs. Done. As a result, the regenerative torque decreases and the braking force decreases, so that the engine speed increases. Then, when the rotational speed of the engine increases, the control returns to the original and the regenerative torque increases.

  The regenerative torque generated by the motor generator is not limited to the regenerative torque limit (regenerative torque limit) because the engine rotation speed cannot be reduced below the power generation capacity of the motor generator or the idling rotation speed. Called).

  When this regenerative torque limit is reached, control is performed to reduce (weaken) the regenerative torque. As a result, the engine speed increases, the regenerative torque is strengthened, the engine speed decreases, and the regenerative torque is reduced. The above-described control of hitting the torque limit is repeated.

  By performing such regenerative torque control, when viewed on the time axis, wavy fluctuations in engine rotation speed occur, and drivability deteriorates.

  FIG. 3B shows the relationship between the regenerative torque and the engine rotation speed in the conventional regenerative control, and FIG. 4B shows this on the time axis.

  An object of the present invention is to improve the deterioration of drivability due to such wavy fluctuations between the regenerative torque and the engine rotation speed. An object of the present invention is to provide a hybrid vehicle that stabilizes the idling state when the hybrid vehicle runs on a slope in an idling state and does not cause a wavy engine rotation speed, and thus a wavy fluctuation in the vehicle speed.

  The present invention responds to an increase in engine speed when the accelerator pedal is released, regenerative braking is performed, and the regenerative torque reaches the regenerative limit and the regenerative torque is reduced when the vehicle travels down a hill. Thus, the regenerative torque is suppressed from increasing, and the regenerative torque is controlled to be constant.

  As a result, even if the engine rotation speed temporarily increases, the regenerative torque is controlled to be constant, so that the engine rotation speed converges to a value that balances the regenerative torque according to the downward gradient. The engine speed does not fluctuate.

  The same applies to the case where the braking control is performed not by the hybrid vehicle but by a retarder that performs braking in which the engine rotational speed decreases due to the regenerative torque. It is possible to suppress the occurrence of wavy fluctuations by converging to a value that balances with the regenerative torque according to.

  That is, according to the present invention, in a regenerative control device that generates a braking force by operating a generator directly connected to an axle, the rotational speed of the internal combustion engine is reduced by the regenerative torque of the generator, and the rotational speed of the axle is predetermined. When the rotational speed limit is reached, control means for suppressing an increase in the regenerative torque of the generator is provided.

  The present invention also includes an internal combustion engine, a motor generator directly connected to the internal combustion engine, and control means for performing braking control by operating the motor generator as a generator with the operation amount of an accelerator pedal as input information. In the hybrid vehicle, the control means may be configured to regenerate by the motor generator when the accelerator pedal is released and the rotation speed of the internal combustion engine decreases due to the regeneration torque of the motor generator and reaches a predetermined rotation speed limit. A means for suppressing an increase in torque is provided.

  The predetermined rotational speed limit may be an idling rotational speed of the internal combustion engine.

  In the present invention, when the regenerative torque is automatically throttled, even if the engine rotational speed temporarily increases, it immediately converges to a constant rotational speed and there is no fluctuation in the wavy engine rotational speed. The ability is improved. In particular, in the case where the motor generator generates a large regenerative torque such as a hybrid vehicle, the discomfort given to the driver due to the fact that the fluctuation of the wavy engine rotation speed is eliminated is great.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a hybrid power unit including an internal combustion engine according to an embodiment of the present invention. The engine 1 is a main power engine of a vehicle, and is a diesel engine in this example. One end of the rotating shaft of the motor generator 2 is fixedly connected to the output shaft of the engine 1. The input shaft of the transmission 5 is connected to the other end of the rotating shaft of the motor generator 2 through the clutch 3. The output shaft of the transmission 5 is connected to the drive axle via a differential gear outside the figure. The motor generator 2 is an AC rotating machine, and three-phase AC from the inverter 4 is supplied to the stator electric winding. This three-phase AC generates a rotating magnetic field around the rotating shaft of the rotating machine. When discharging, the inverter 4 is supplied with a direct current from the battery 9, and charged with the battery 9 from the inverter 4 during charging.

  The inverter 4 is controlled by a hybrid control circuit (HV-ECU) 10. The hybrid control circuit 10 inputs signals from sensors such as the gear position sensor 6, the rotation sensor 7, the vehicle speed sensor 8, the accelerator sensor 13, the current detection means 17, and the charge amount detection means 16 through the interface circuit 11. The inverter 4 is controlled.

  The phase rotation speed (that is, the frequency) of the three-phase AC supplied from the inverter 4 to the motor generator 2 is controlled by the hybrid control circuit 10. When the phase rotation speed of the three-phase alternating current becomes larger than the mechanical rotation speed of the motor generator 2, the motor generator 2 acts as an electric motor and gives auxiliary rotational acceleration to the output rotation shaft of the engine 1. When the phase rotation speed of the three-phase alternating current becomes smaller than the mechanical rotation speed of the motor generator 2, the motor generator 2 acts as a generator, and this vehicle drive axle (see FIG. Braking force is generated against the outside. When the motor generator 2 acts as a generator, it operates as a vehicle braking device, and the generated electric power is converted into a direct current by the inverter 4 to charge the battery 9. The current supplied from the battery 9 drives the motor generator 2 via the inverter 4, and the energy generated by the braking force is regenerated as the driving power of the vehicle, and the energy can be used effectively.

  Here, the feature of the present invention is that when the accelerator pedal is released by running downhill or the like and the regenerative mode is set, and the regenerative torque reaches the low rotation torque limit of the engine 1, the regenerative torque is obtained. There is a place to control so that it does not increase.

  Hereinafter, the control that suppresses the increase in the regenerative torque of the motor generator 2 is referred to as idle stabilization control.

  The idle stabilization control will be described with reference to FIGS. 3 and 4.

  As shown in FIG. 3, a regenerative torque limit represented by a line abc is set for the engine speed and the regenerative torque of the motor generator. Within this limit frame, the regenerative torque according to the engine speed and load is calculated, and the AC frequency is applied from the inverter 4 so that the motor generator 2 generates the calculated regenerative torque. Since the engine rotational speed decreases below the idling rotational speed when it reaches the left side of the regenerative torque limit line bc, below this, the regenerative limit is set so that the engine rotational speed does not decrease due to the regenerative torque. ing.

  Here, when the engine speed decreases due to regeneration started from point A in FIG. 3A and hits the limit line represented by bc, in this embodiment, the direction of point B, that is, The regenerative torque is controlled to be constant. This control means that the hybrid control circuit 10 controls the AC frequency that the inverter 4 gives to the motor generator 2 so that the regenerative torque becomes constant even when the engine speed increases. At this time, since the regenerative torque is constantly reduced, the engine speed increases. However, after a predetermined time, the engine rotation speed converges to a value that balances with the regenerative torque of the downward gradient. This is shown in FIG.

  Conventionally, as shown in FIG. 3 (b), the regenerative torque and the engine rotation speed fluctuate in a loop shape, so that the engine rotation speed fluctuates in a wave shape as shown in FIG. 4 (b). It was. As shown in FIG. 4 (a), when the regenerative torque hits the limit line, the engine rotation speed once increases, but the regenerative torque has a magnitude corresponding to the descending slope of the slope and is balanced with this regenerative torque. The engine speed converges to the value. As a result, the phenomenon that the engine rotational speed fluctuates in a wavy manner is eliminated, and the drivability does not deteriorate.

  Further, as shown in FIG. 3A, when the regenerative torque at the start of regeneration is C, when it hits the limit line b-c as shown by the broken line, the regenerative torque is increased at that point and the regenerative torque is increased. Therefore, the engine rotation speed reaches D and stabilizes at that speed.

  This will be described with reference to the flowchart of FIG. FIG. 2 is a flowchart showing an example of regenerative control according to the embodiment of the present invention.

  When the accelerator pedal is released and regenerative braking control is started, a regenerative torque corresponding to the vehicle speed and load at that time is calculated (S1, S2). When the calculated regenerative torque is smaller than the low rotational torque limit (when it is on the left side of the line bc), it is determined that the idle stabilization control is not necessary. When the regenerative torque is on the right side of the line bc, it is determined that there is idle stabilization control (S4). Here, when there is idle stabilization control, it is determined whether there is a torque increase suppression limit release, and when there is no suppression limit release, control to suppress the torque increase is started (S6, S7). The control is continued until the regenerative torque becomes equal to the torque increase suppression limit (S8 to S10). When the calculated regenerative torque is smaller than the low rotation torque limit and there is no need for idling stabilization control, the regenerative torque decreases on the limit line, and finally the regenerative control is performed by stopping the vehicle. Is finished (S11).

  If regenerative control is not performed, there is no idle stabilization control, so torque increase suppression limit control in idle stabilization control is canceled (S12, S13).

The block block diagram of this invention Example apparatus. The flowchart explaining control of the Example of this invention. The figure explaining the control of the regenerative torque by regenerative torque control of this invention Example, and the regenerative torque in a prior art. The figure explaining the time change of the regenerative torque and engine speed in the present invention example and the prior art.

Explanation of symbols

1 Engine 2 Motor generator (MG)
3 Clutch (CL)
4 Inverter 5 Transmission 6 Gear position sensor 7 Rotation sensor 8 Vehicle speed sensor 9 Battery 10 Hybrid control circuit (HV-ECU)
DESCRIPTION OF SYMBOLS 11 Interface circuit 12 Accelerator pedal 13 Accelerator sensor 14 Fuel injection pump 15 Electronic governor 16 Charge amount detection means 17 Current detection means

Claims (3)

In a regenerative control device that generates braking force by operating a generator directly connected to an axle,
A regenerative control device comprising control means for suppressing an increase in the regenerative torque of the generator when the rotational speed of the internal combustion engine decreases due to the regenerative torque of the generator and the rotational speed of the axle reaches a predetermined rotational speed limit. In a hybrid vehicle comprising an internal combustion engine, a motor generator directly connected to the internal combustion engine, and control means for operating the motor generator as a generator and performing braking control using the operation amount of an accelerator pedal as input information,
When the accelerator pedal is released and the regenerative torque of the motor generator decreases the rotational speed of the internal combustion engine to reach a predetermined rotational speed limit, the control means suppresses an increase in the regenerative torque by the motor generator. A hybrid vehicle characterized by comprising means.   The hybrid vehicle according to claim 2, wherein the predetermined rotational speed limit is an idling rotational speed of an internal combustion engine.

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