JP2800451B2 - Regenerative energy absorber - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for absorbing regenerative energy, and more particularly to an apparatus for absorbing regenerative energy generated during regeneration in a hybrid vehicle driven by a combination of an engine and a motor.

[0002]

2. Description of the Related Art In recent years, from the viewpoint of environmental improvement and noise reduction,
Electric vehicles are attracting attention. However, electric vehicles have a problem that, as an energy source, a battery mounted on the vehicle takes a long time to charge the battery, and the traveling distance per charge cannot be significantly increased from the capacity. On the other hand, in recent years, a hybrid vehicle that can compensate for the drawbacks of an electric vehicle while reducing the problems of exhaust gas and noise of an internal combustion engine vehicle has been attracting attention.

[0003] Two types of drive systems are known for this hybrid vehicle: a series system and a parallel system. The series system is a system in which the internal combustion engine is used only for power generation, and the generated power is used for charging a battery and a motor. The parallel system is a system in which the internal combustion engine is used not only for power generation but also for direct driving of an automobile.

[0004] In either system, regenerative braking in which a motor operates as a generator is used to obtain a braking force equivalent to an engine brake. The energy obtained by the regenerative braking is most easily consumed by the discharge resistor.

[0005] However, simply consuming energy as heat is wasteful.
Since there is a demand for extending the traveling distance per charge, regenerative energy is used for charging a battery. However, this regenerative energy is generated by a braking force required according to traveling, and the amount of the generated regenerative energy cannot be controlled. Therefore, when the regenerative energy is directly returned to the battery, the battery may be overcharged. And, when charging beyond the capacity, problems such as decomposition of electrolyte, gas generation, heating, etc. occur,
It is known to dramatically shorten the life. Therefore, a discharge resistor is provided to absorb extra regenerative energy,
In this discharge resistor, regenerative energy is consumed.

[0006]

However, in regenerative energy absorption using a discharge resistor, there is a problem in that the discharge resistance becomes considerably large, which leads to an increase in weight and a deterioration in space efficiency. On the other hand, a system that relies on mechanical braking for most of the braking force to prevent large regenerative energy from being generated is conceivable. However, another problem arises in that the regenerative energy cannot be used efficiently.

Accordingly, an object of the present invention is to provide a regenerative energy absorbing device capable of efficiently absorbing regenerative energy without increasing the size of the device.

[0008]

SUMMARY OF THE INVENTION The present invention provides an engine which is driven by being supplied with fuel, a generator which generates electric power by a driving force of the engine, and which can also operate as a motor, and an electric power from the generator. A first inverter that outputs a predetermined DC power and can also convert the DC power to an AC power, a battery that receives the supply of the DC power from the first inverter and outputs the DC power, A second inverter that outputs DC power output from the battery as AC power and converts AC power to DC power during regeneration and supplies the DC power to the battery, and is driven by power from the second inverter. At the same time, the motor detects the voltage of the battery and the motor that generates electric power during regeneration and supplies the electric power to the second inverter. Compares the pressure detecting means, a battery voltage detected by the voltage detecting means with a predetermined set value,
When the battery voltage is equal to or higher than a set value, regenerative power output from the second inverter is supplied to the generator via the first inverter, and the generator is used as a load for the engine. If it drives as a motor door
Retardant monitor, and control means for cutting the supply of fuel to the engine, a portion of the energy generated during regenerative
It is characterized in that the supply of the fuel is absorbed by the motor drive of the generator having the cut engine as a load.

[0009]

In the regenerative energy absorbing device of the present invention, during normal operation, electric power is generated by a generator by the driving force of an engine that is supplied with fuel and driven, and this electric power is supplied to a battery to perform charging. Electric power is supplied to the motor through the second inverter to drive the electric vehicle. On the other hand, during regenerative braking, electric power generated in the motor is used for charging the battery via the second inverter. During regenerative braking, the battery voltage is detected. If the battery voltage is equal to or higher than a set value, electric power from the second inverter is supplied to the generator via the first inverter, and the motor is driven using the engine as a load. Absorbs regenerative energy. And, at the time of regenerative energy absorption, and are the fuel cut to the engine
Because the absorption efficiency can be further increased.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of a regenerative energy absorbing device according to one embodiment of the present invention. In the figure, an engine 1 is an internal combustion engine that is driven by receiving supply of fuel from a fuel tank 10 via a fuel valve 11 and outputs a rotational force. The generator 2 is driven by the engine 1,
Generates AC power. Inverter 3 includes generator 2
Is converted into DC power, and the generator 2 is driven as a motor when absorbing regenerative energy. Battery 5 is charged with DC power from inverters 3 and 6, and outputs desired DC power. The inverter 6 converts the DC power from the battery 5 into a desired AC current and supplies the AC power to the drive motor 7. A drive motor 7 and an AC-driven induction motor are used, and the drive motor 7 rotates tires 8 of the hybrid vehicle. In addition, the switching control of the inverter 6 normally uses vector control according to the torque command. The drive motor 7 and the tire 8 are mechanically connected via a drive mechanism such as a gear (not shown). Then, during regenerative braking, the inverter 6 converts AC power generated in the drive motor 7 into DC power and supplies the DC power to the battery 5.

The brake switch 9 is a brake switch that is turned on when braking is applied to the hybrid vehicle. A signal for turning the brake switch on and off is supplied to the electronic control unit 4. Here, an output from a voltmeter 12 for detecting the voltage of the battery 5 is also supplied to the electronic control unit 4, and the generator 2, the driving motor 7, and the fuel valve 11 are controlled in accordance with these input signals. I do. Here, since the inverter 3 and the inverter 6 are directly connected, the battery 5 has a role as a buffer for absorbing and adjusting the energy difference between the generator 2 and the driving motor 7.

Next, the operation of the above-described configuration will be described with reference to the flowchart of FIG.

During power running, fuel is supplied to the engine 1 from a fuel tank 10 via a fuel valve 11, and the engine 1 operates using the generator 2 as a generator. The electric power from the generator 2 is supplied to the drive motor 7 via the inverter 3, the battery 5, and the inverter 6, and the drive motor 7 is driven to drive the hybrid vehicle.

On the other hand, the electronic control unit 4 monitors the state of the brake switch 9 (S1). When the ON of the brake switch 9 is detected, a regeneration command is issued from the electronic control unit 4 to the inverter 6 (S2). as a result,
The drive motor 7 acts as a generator by the torque transmitted from the tire 8 to the drive motor 7, and the AC power obtained by the drive motor 7 is converted into DC power by the inverter 6 and output. Here, the electronic control unit 4 detects whether the voltage of the battery 5 from the voltmeter 12 is higher than a set value (S3).
Using the output of the charging of the battery remains 5. In contrast, if the voltage of the battery 5 is equal to or greater than a preset value, the fuel valve 11 is turned off and fuel cut from the fuel tank 10 to the engine 1 (S 4). Note that this fuel cup
Otherwise, the efficiency of energy absorption will decrease. next,
A command is issued to the inverter 3 to drive the generator 2 as a motor (S5). As a result, the generator 2 is motor-driven by the electric power supplied from the inverter 3 and rotates with the engine 1 as a load. The engine 1 functions as a kind of air compressor by fuel cut, so that it can absorb regenerative energy.
Therefore, when excessive regenerative energy is generated, the voltage of battery 5 can be suppressed to a range not exceeding its allowable set value. In addition, the voltage-current characteristics of a general battery have a characteristic that the terminal voltage at the time of charging rises as shown in FIG. Therefore, the battery 5 is measured by the voltmeter 12.
By monitoring the terminal voltage of the battery 5, it is possible to determine whether the battery 5 can be charged (absorb regenerative energy).

As described above, since the engine 1 can be used as a load during regenerative braking, it is possible to prevent the battery 5 from being overcharged by excessive regenerative energy. Furthermore, if the generator 2 is used as a starter motor by the inverter 3, it is not necessary to separately provide a starter motor necessary for the engine 1, and cost and weight can be reduced.

[0017]

As described above, the regenerative energy absorbing apparatus according to the present invention provides a fuel cut for regenerative energy.
The configuration is such that the battery is absorbed by driving the generator with the engine as a load, so that the overcharge of the battery can be prevented without mounting a discharging resistor.
Therefore, there is an effect that weight reduction and effective braking force can be secured.

[Brief description of the drawings]

FIG. 1 is a block diagram of a regenerative energy absorbing device according to one embodiment of the present invention.

FIG. 2 is a flowchart for explaining the operation of the configuration of FIG. 1;

FIG. 3 is a voltage-current characteristic diagram of a general battery.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 engine 2 generator 3 inverter 4 electronic control unit 5 battery 6 inverter 7 drive motor 8 tire 9 brake switch 10 fuel tank 11 fuel valve

Claims (1)

(57) [Claims] 1. An engine which is driven by supplying fuel, a generator which generates electric power by a driving force of the engine and which can also operate as a motor, and outputs electric power from the generator as predetermined DC electric power. A first inverter capable of converting DC power to AC power, a battery receiving DC power from the first inverter and outputting DC power, and a DC power output from the battery. Is output as AC power, and at the time of regeneration, a second inverter that converts AC power into DC power and supplies the DC power to the battery; and a second inverter that is driven by power from the second inverter and generates power during regeneration. A motor for supplying the voltage to the second inverter, a voltage detecting means for detecting a voltage of the battery, The battery voltage detected by the detecting means is compared with a predetermined set value, and when the battery voltage is equal to or higher than the set value, regenerative power output from the second inverter is supplied to the generator via the first inverter. Then, the generator is driven as a motor having the engine as a load, and fuel is supplied to the engine.
Control means for cutting off the supply, and the fuel supply cuts off part of the energy generated during regeneration.
Regenerative energy absorbing device, characterized in that to absorb Sorted engine by the motor drive of the generator to the load.