JP2001268702A - Power system for electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power system for an electric vehicle, which controls distribution regenerative output power in an optimum manner. SOLUTION: This power system is constituted such that a power absorber device 11 capable of absorbing regenerative output power of a motor 5 for running and a changeover switch 13 interrupting a circuit supplying the regenerative output power of the motor 6 for running to the power absorber device 11 are provided to supply the output power to the power absorber device 11 through the changeover switch 13 when a battery device 4 is placed in a fully charged condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply system for an electric vehicle that performs regenerative power generation by rotating force from a drive system of a vehicle when the vehicle is decelerated or braked.

[0002]

2. Description of the Related Art There has been known a hybrid vehicle having both an engine and a motor (a rotating electric machine serving both as an electric motor and a generator) as power sources of a vehicle and running with one or both driving forces. I have.

In such a hybrid vehicle, when the vehicle is decelerated or braked, regenerative operation is performed in which the motor is operated as a generator by the rotational force from the drive system of the vehicle, and the deceleration energy of the vehicle is used for charging the power storage device. It has become.

[0004]

However, for example, in a driving condition in which the vehicle travels on a long downhill,
When the regenerative operation continues and the power storage device is fully charged,
Since the regenerative power generation is stopped, the motor does not apply a braking force by the regenerative power generation, and there is a problem that a load of a wheel brake or the like as another braking device increases.

[0005] The present invention has been made in view of the above problems, and has as its object to provide a power supply system for an electric vehicle that optimally controls the distribution of regenerative power.

[0006]

According to a first aspect of the present invention, a driving force is transmitted to a driving system of a vehicle by electric power from a power storage device, and regenerative power is generated by a rotating force from the driving system of the vehicle when the vehicle is decelerated or braked. The present invention is applied to a power supply system of an electric vehicle including a rotating electric machine.

A power absorbing device capable of absorbing the regenerative power of the rotating electric machine, a changeover switch for intermittently connecting a circuit for supplying the regenerative power of the rotating electric machine to the power absorbing device,
Power absorption control means for supplying regenerative power to the power absorbing device via the changeover switch when the power storage device is fully charged.

According to a second aspect of the present invention, in the first aspect, the power absorbing device includes a resistor and a capacitor interposed in parallel in a circuit through which the regenerative power generation current flows to limit the current supplied to the capacitor. Was provided.

In a third aspect based on the second aspect, the current limiting means comprises a semiconductor switching element.

In a fourth aspect based on the second aspect, the current limiting means is constituted by a variable resistor.

According to a fifth aspect of the present invention, in any one of the second to fourth aspects, a polarity changeover switch for changing the polarity of the capacitor is provided, and the polarity changeover switch is periodically operated.

[0012]

According to the first aspect of the present invention, for example, in a driving condition where a vehicle travels on a long downhill,
When the regenerative operation is continued and the power storage device is fully charged, regenerative power is consumed by the power absorbing device. As a result, the regenerative operation is continued even in the fully charged state and the braking force is applied, so that it is possible to avoid increasing the load on the wheel brake and the like as another braking device.

In the second invention, the power absorbing device converts the regenerative power into thermal energy via a resistor and temporarily stores the thermal energy via a capacitor.

The current limiting means limits the current supplied to the capacitor to prevent the capacitor from being charged instantaneously. Thereby, for example, a rapid change in current in the inverter is suppressed, and stable operation is maintained.

In the third aspect of the present invention, since the current limiting means limits the current by operating the semiconductor switching element, it generates less heat and can be applied to a large capacity.

In the fourth invention, the current limiting means limits the current supplied to the capacitor via the variable resistor.

In the fifth aspect, the direction of the current stored in the capacitor is periodically reversed, so that the voltage between the terminals of the capacitor repeatedly increases, and the current continues to flow.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a power supply system mounted on a series hybrid vehicle will be described below with reference to the accompanying drawings.

As shown in FIG. 1, an engine 1 includes a generator 2
And the power generated by the generator 2 is supplied to the main power storage device 4 via the rectifier 3 and to the traveling motor 6 via the inverter 5. The drive system of the vehicle (not shown) is driven by the traveling motor 6. In the figure, 8 is an auxiliary power storage device, 7 is a DC-DC converter for charging the auxiliary power storage device 8, and 9 is an auxiliary machine.

The main power storage device 4 is constituted by a chemical battery or a number of capacitors, and can store a predetermined electric power.

The inverter 5 converts the DC power of the main power storage device 4 into AC power and supplies the AC power to the traveling motor 6, and converts the AC power generated by the traveling motor 6 into DC power and charges the main power storage device 4. I do.

The controller 20 includes a microcomputer and its peripheral parts, controls the operation of the engine 1 in accordance with the operating conditions of the vehicle, controls the power generation via the rectifier 3, and the driving motor via the inverter 5. 6 to control the rotation speed, output torque, regenerative power, and the like.

The above is an example of a basic configuration of a hybrid vehicle to which the present invention can be applied, and an object of the present invention is to optimally control the regenerative power generation distribution of such a hybrid vehicle.

According to the present invention, there is provided a changeover switch 1 provided with a power absorbing device 11 in parallel with the main power storage device 4 for interrupting a circuit for supplying regenerative power generated by the traveling motor 6 to the power absorbing device 11.
3 is provided. The changeover switch 13 has an OFF position for supplying regenerative power to the main power storage device 4 and an ON position for supplying regenerative power to the power absorbing device 11.

As shown in FIG. 2, the power absorbing device 11 is mainly composed of a variable resistor 15. Variable resistor 15
Converts the regenerative power to heat energy,
The resistance value changes based on the control signal from 0, and the power consumption increases as the resistance value, that is, the absorbed power increases.

The power absorbing device 11 has a capacitor 16 interposed in parallel with the variable resistor 15. The capacitor 16 has a function of temporarily storing a predetermined regenerative power, and is configured by combining a plurality of capacitors in series and parallel according to the required power storage.

The power absorbing device 11 includes a switching converter 17 in series with the capacitor 16 as current limiting means for limiting the current supplied to the capacitor 16. The switching converter 17 is configured by a semiconductor switching element, adjusts a current supplied to the capacitor 16 based on a control signal from the controller 20,
Prevents the capacitor 16 from being charged momentarily.

The controller 20 determines a fully charged state in which the chargeable power of the main power storage device 4 is equal to or less than a predetermined value, and controls the regenerative power to be supplied to the power absorbing device 11 via the changeover switch 13 in the fully charged state. Do.

FIG. 3 is a flow chart showing the above control routine.
Is periodically executed by interrupt processing or the like as a part of the overall control of the hybrid vehicle by the above.

To describe this, first, after inputting the driving state detection signal, it is determined whether or not the vehicle is in a deceleration state (steps 1 and 2). The deceleration state is determined based on, for example, signals from a vehicle speed sensor and an accelerator pedal sensor (not shown) based on the fact that the vehicle speed is more than a certain level and the accelerator pedal is not depressed. When the vehicle is not in the decelerating state, regenerative power generation is not performed. Therefore, the process proceeds to step 9, bypassing the following processing, and the changeover switch 13 is turned off to shut off the power absorbing device 11.

When it is determined that the vehicle is decelerating, the main power storage device 4
Battery SOC (State of Charge)
And the regenerative power WE of the traveling motor 6 as well as the chargeable power WH based on the detected value.

Subsequently, the routine proceeds to step 5, where the chargeable electric power W
H and the regenerative power WE are compared. At this time, WH> WE
Then, the main power storage device 4 has enough room to charge,
Proceeding to step 9, the changeover switch 13 is turned off to shut off the power absorbing device 11. On the other hand, when WH ≦ WE, the changeover switch 13 is turned on to shut off the main power storage device 4, and the switching converter 17 and the variable resistor 15 are controlled according to the regenerative power WE (steps 6 to 6).
8). The processing performed in steps 5 and 6 corresponds to the power absorption control unit of the present invention.

With the above-described configuration, for example, when the regenerative operation is continued and the main power storage device 4 is fully charged under the operating conditions in which the vehicle travels on a long downhill, the regenerative power is supplied to the power absorbing device. Consumed at 11. As a result, the traveling motor 6 continues to generate regenerative electric power and applies a braking force, so that it is possible to avoid an increase in the load of a wheel brake or the like as another braking device.

The power absorbing device 11 converts the regenerative power into thermal energy via the variable resistor 15 and temporarily stores the thermal energy via the capacitor 16. The electric power stored in the capacitor 16 is consumed via the variable resistor 15, but may be consumed for driving the accessory 9 and the like.

The switching converter 17 limits the current supplied to the capacitor 16 to prevent the capacitor 16 from being charged instantaneously. As a result, a rapid change in current in the inverter 5 is suppressed, and the inverter 5
The stable operation of is maintained. Since the switching converter 17 limits the current by the operation of the semiconductor switching element, the switching converter 17 generates less heat and can be applied to a large capacity.

Next, in another embodiment shown in FIG. 4, the main power storage device 4 is always connected to the traveling motor 6, and the power absorbing device 11 is selectively connected via the changeover switch 23. Is also good. The changeover switch 23 is the power absorbing device 1
1 and an ON position for supplying regenerative power to the power absorbing device 11 as well.

Next, in another embodiment shown in FIG. 5, a variable resistor 25 is interposed in series with the capacitor 16 as current limiting means for limiting the current supplied to the capacitor 16. The variable resistor 25 changes its resistance value based on a control signal from the controller and suppresses the capacitor 16 from being instantaneously charged.

Next, in another embodiment shown in FIG. 6, a plurality of resistors 26 having different resistance values are interposed in series with the capacitor 16 as current limiting means for limiting the current supplied to the capacitor 16. A switch 27 for selectively connecting one of the resistors 26 is provided. The switch 27 is operated to switch based on a control signal from the controller, and the capacitor 16
Suppresses instantaneous charging.

Next, another embodiment shown in FIG. 7 is provided with a pair of polarity changeover switches 31 and 32 for switching the polarity of the capacitor 16 of the power absorbing device 11. The polarity changeover switches 31, 32 are periodically switched based on a control signal from the controller.

In this case, the flow direction of the current stored in the capacitor 16 is periodically reversed, so that the voltage between the terminals of the capacitor 16 is changed from -V1 to + V, as shown in FIG.
It repeatedly rises to V1 and the current continues to flow.

Although the above description has been made in connection with the series hybrid electric vehicle, the present invention relates to other electric vehicles including a parallel hybrid electric vehicle, an electric vehicle without a generator, and an electric vehicle powered by a fuel cell. Of the power supply system.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a power supply system of an electric vehicle according to an embodiment of the present invention.

FIG. 2 is a circuit diagram of the same power absorbing device.

FIG. 3 is a flowchart showing control contents.

FIG. 4 is a circuit diagram of a changeover switch according to another embodiment.

FIG. 5 is a circuit diagram of a power absorption device showing still another embodiment.

FIG. 6 is a circuit diagram of a power absorption device showing still another embodiment.

FIG. 7 is a circuit diagram of a power absorbing device according to still another embodiment.

FIG. 8 is a charge / discharge characteristic diagram of the capacitor.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 generator 3 rectifier 4 main power storage device 5 inverter 6 traveling motor 11 power absorbing device 13 changeover switch 15 variable resistor 16 capacitor 17 switching converter 20 controller

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Masakazu Sasaki F-term (reference) in Nissan Diesel Kogyo Co., Ltd., Ichi-Chome Ichichome, Ageo-shi, Saitama 5H115 PA15 PC06 PG04 PI13 PI16 PI24 PI29 PI30 PO02 PO06 PO09 PU08 PU26 PV02 PV07 PV09 QI03 QI04 QI07 QI15 QN03 TB01 TI01 TO21

Claims (5)

[Claims] 1. A power supply system for an electric vehicle including a rotating electric machine that transmits driving force to a driving system of a vehicle by electric power from a power storage device and that generates regenerative power by rotating force from the driving system of the vehicle when the vehicle is decelerated or braked. In the above, a power absorbing device capable of absorbing regenerative power generated by the rotating electric machine, a changeover switch for interrupting a circuit for supplying regenerative power generated by the rotating electric machine to the power absorbing device, and when the power storage device is fully charged Power absorption control means for supplying regenerative power to the power absorption device via the changeover switch. 2. The power absorbing device according to claim 1, wherein a resistor and a capacitor are interposed in parallel in a circuit through which a regenerative power generation current flows, and current limiting means is provided for limiting the current supplied to the capacitor. A power supply system for an electric vehicle according to claim 1. 3. A power supply system for an electric vehicle according to claim 2, wherein said current limiting means comprises a semiconductor switching element. 4. The power supply system for an electric vehicle according to claim 2, wherein said current limiting means comprises a variable resistor. 5. The electric device according to claim 2, further comprising a polarity switch for switching the polarity of the capacitor, wherein the polarity switch is switched periodically. Automotive power system.