JP2000050401A - Power source unit for hybrid electric automobile - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a hybrid electric automobile in which reverse power transmission from an auxiliary power storing means to a main power storing means is realized by using a simple circuit constitution. SOLUTION: A main power storing means 1 of a hybrid electric automobile charges an auxiliary power storing means 2 through a DC/DC converter, which is provided with a high voltage side AC to DC converting circuit 5 on the main power storing means side, a transformer 6, and a low voltage side AC to DC converting circuit 7 on the auxiliary power storing means side. The respective unit power storing means 11, 12 of the main power storing means 1 are connected in parallel, and power is supplied from the auxiliary power storing means 2 to the main power storing means 1. When the motor 3 for starting an engine is started, the respective unit power storing means 11, 12 are connected in series, and power is supplied to the motor 3 for starting the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a power supply device for a hybrid electric vehicle.

[0002]

2. Description of the Related Art In a conventional hybrid electric vehicle in which electric power is supplied from a generator driven by an internal combustion engine to a main power storage means and a traveling motor, the internal combustion engine is started by an engine starting motor supplied from the main power storage means. Note that the above-described generator or the like can be used as the starting motor.

Japanese Unexamined Patent Publication No. 62-173901 discloses an electric power supply system for supplying electric power from a main power storage means for supplying power to a traveling motor of an electric vehicle to a auxiliary power storage means for driving auxiliary equipment via a DC / DC converter for supplying auxiliary equipment. Proposing a car. In this type of electric vehicle, high-voltage equipment such as a traveling motor can be supplied with much higher voltage (for example, 300 V) than auxiliary equipment that is normally supplied with low voltage (for example, 12 V). In addition, there is an advantage that the power supply voltage with small voltage fluctuation can be supplied to the auxiliary equipment.

[0004]

However, the above-mentioned hybrid electric vehicle has a smaller capacity of the main power storage means than a pure electric vehicle without an engine, and thus the engine is started due to fluctuations in the remaining capacity or when the engine is left for a long period of time. May not be possible. In this case, in a hybrid electric vehicle having the auxiliary power storage means and the DC / DC converter for auxiliary equipment, the engine is started by supplying power to the engine starting motor from the auxiliary power storage means even when the remaining amount of the main power storage means is insufficient. It is possible to do.

[0005] That is, the auxiliary power storage means always stores power of a certain voltage level for supplying power to various auxiliary equipment, and when an emergency situation occurs in which the engine cannot be started by the main power storage means, the auxiliary power storage means is used. It is important to start the engine first prior to supplying stable voltage to the machine, and if the engine can be started, recharging of the auxiliary power storage means should be able to be quickly realized.

However, in order to drive the traveling motor by the auxiliary power storage means as described above, a new step-up DC / DC converter for boosting the low voltage of the output voltage of the auxiliary power storage means and applying it to the traveling motor is used. There is a problem that the circuit configuration has to be complicated and the device cost increases. The present invention has been made in view of the above problems, and has as its object to provide a power supply device for a hybrid electric vehicle in which reverse power transmission from the auxiliary power storage means to the main power storage means is realized with a simple circuit configuration. I have.

[0007]

According to the structure of the first aspect, the main power storage means of the hybrid electric vehicle is DC / D
The auxiliary power storage means is charged through the C converter. DC /
The DC converter has a high-voltage side AC / DC conversion circuit on the main power storage means side, a transformer, and a low voltage side AC / DC conversion circuit on the auxiliary power storage means side.

The high-voltage side AC / DC conversion circuit performs a so-called inverter operation to supply AC current to the primary winding of the transformer when power is supplied from the main power storage means to the auxiliary power storage means. When power is supplied to the power supply, a so-called rectifying operation is performed. The low-voltage side AC / DC conversion circuit performs a so-called rectifying operation when power is supplied from the main power storage unit to the auxiliary power storage unit, and performs a so-called inverter operation when power is supplied from the auxiliary power storage unit to the main power storage unit, so that the secondary winding of the transformer is connected. Supply alternating current.

In particular, in this configuration, the unit power storage units of the main power storage unit are connected in parallel to supply power from the auxiliary power storage unit to the main power storage unit, and the unit power storage units are connected in series when the engine starting motor is started. Power to the motor for starting the engine.
With this configuration, the following operation and effect can be obtained. First, since both the auxiliary power storage means charging and the main power storage means charging can be performed using a common power supply device, the power supply device can be reduced in size and weight, installation space can be reduced, and the number of components can be reduced. .

When at least one of the main power storage means and the auxiliary power storage means is constituted by a battery, and when the battery is charged, it is necessary to charge the battery with a charging voltage considerably larger than a specified discharge voltage value. Even when at least one of the main power storage means and the auxiliary power storage means is constituted by a capacitor (especially a large-capacity electric double-layer capacitor), since the terminal voltage of the capacitor is significantly reduced by discharging, sufficient discharge power is obtained. Need to be charged with a charging voltage considerably larger than a specified discharge voltage value.

As a result, the DC / DC converter comprising the high-voltage side AC / DC conversion circuit, the transformer, and the low-voltage side AC / DC conversion circuit has a smaller DC voltage than the reciprocal of the DC voltage step-down ratio at the time of charging the main power storage means. A problem arises in that the voltage boost ratio must be set to a considerably high value. On the other hand, in this configuration, since the boosting switching circuit that operates only when the main power storage means is charged is provided between the high-voltage side AC / DC conversion circuit and the main power storage means, the configuration and operation of the DC / DC converter are not changed. This difference in voltage conversion ratio is absorbed without any change, so that a common power supply device can perform bidirectional charging of both power storage means, thereby achieving reduction in size and weight of the power supply device and reduction in the number of components. it can.

According to the second aspect of the present invention, since the unit power storage means further comprises an electric double layer capacitor, the unit power storage means can be reduced in size and weight.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In a hybrid electric vehicle according to the present invention, a main power storage means supplies power to an engine starting motor to start an engine. As a motor for starting the engine, a generator driven by the engine to generate power and charge the main power storage means is generally used. A traveling motor can be used as the generator.

It is preferable to use a battery or an electric double layer capacitor as the unit power storage means of the main power storage means.
As the switching means, a relay can be used, and a semiconductor switching element can also be used. Preferred embodiments of the present invention will be described with reference to the following examples.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (Configuration) One embodiment of a power supply device for a hybrid electric vehicle according to the present invention will be described with reference to FIG. This power supply device includes a main power storage means 1, an auxiliary power storage means (secondary battery)
2, an engine 3, a generator (running motor) 4, a high voltage circuit 5, a transformer 6, a low voltage circuit 7, a controller 9, a reactor 10, a capacitor 11, a reactor 12, a capacitor 13, a diode 14, and a relay contact 15. I have.

The high-voltage circuit 5 constitutes the high-voltage side AC / DC conversion circuit of the present invention, the low-voltage circuit 7 and the low-voltage side AC / DC conversion circuit of the present invention, and includes the high-voltage circuit 5, the transformer 6, and the low-voltage circuit 7.
Is a DC / DC converter. The main power storage means 1 is connected to a traveling motor 4 composed of, for example, a generator motor so as to be able to exchange power, and the traveling motor 4 is connected to the wheels and the engine 3 so as to be able to cut off transmission torque. There are various types of connection methods between the traveling motor 4, the engine 3, and the wheels (not shown), but the connection is not the gist of the present invention, and therefore the description thereof is omitted.

The main power storage means 1 is a unit power storage means 1 comprising a predetermined number of electric double layer capacitors connected in series.
1, 12 and 2-contact switching relay (switching means) 1
3 and 14. The higher end of the unit power storage means 11 is connected to one end of the motor 4 for starting the engine.
1 is connected to the common terminal of the relay 13.
One of a pair of switching terminals of the relay 13 is connected to the other end of the engine starting motor 4, and the other of the pair of switching terminals of the relay 13 is connected to one of a pair of switching terminals of the relay 14. The other of the pair of switching terminals of the relay 14 is connected to the high-order DC terminal of the high-voltage circuit 5,
4 is connected to the higher end of the unit power storage means 12,
The lower end of the unit power storage means 12 is connected to the other end of the motor for starting the engine.

The high-voltage circuit 5 comprises a so-called bridge circuit, a first phase inverter circuit comprising a series connection of a high-side switch 5a and a low-side switch 5b each comprising an NMOS transistor, and an NMOS transistor respectively.
It comprises a second phase inverter circuit in which a high-side switch 5c and a low-side switch 5d composed of transistors are connected in series, and diodes 5e to 5h connected in anti-parallel to the switches 5a to 5d, respectively. Switch 5a,
The connection point of 5b is connected to one end of the primary winding 6a having a large number of turns of the transformer 6, and the connection point of the switches 5c and 5d is connected to the other end of the primary winding 6a of the transformer 6. The other ends of the high-side switches 5a and 5c are connected to the high-order terminal of the main power storage unit 1 through the reactor 12 and the diode 14 as a high-order power supply terminal of the main power storage unit 1.
The other end of b, 5d is connected to the lower end of the main power storage means 1. The transformer 6 has a pair of small winding secondary windings 6b, 6c wound in opposite directions. Secondary winding 6
b, 6c are connected to each other through the low voltage circuit 7 to the lower end of the auxiliary power storage means 2, and both secondary windings 6b, 6c
Is connected to a higher end of the auxiliary power storage means 2 through a reactor 10.

The low-voltage circuit 7 includes switching elements 7a and 7b each composed of an IGBT,
a, 7b Diodes 7c, 7d connected in anti-parallel to each other
Consists of The controller 9 is a switch 5 of the high voltage circuit 5.
a to 5d and switches 7a and 7b of the low voltage circuit 7 are intermittently controlled. Controller 9 includes unit power storage means 11 and 12.
Each of the switches 5a to 5 based on the terminal voltage of the auxiliary storage means 2 and the auxiliary storage means charging signal and the main storage means charging signal input from an external controller (not shown).
d, 7a, 7b and the relays 13, 14 are controlled to open and close.

(Operation) The operation of the power supply device performed by the controller 9 will be described with reference to the flowchart of FIG. After the reset operation performed when the power is turned on,
It is checked whether an auxiliary storage means charging command signal from an external controller (not shown) for vehicle control exists, and if not, it is determined whether the terminal voltage V2 of the auxiliary storage means 2 is lower than a predetermined minimum threshold value VT2. When it is determined that V2 is equal to or higher than VT2, it is determined that the auxiliary power storage means is not required to be charged, and the process proceeds to S108 described later.

On the other hand, if there is a charge command signal for auxiliary storage means, or if terminal voltage V2 is lower than a predetermined minimum threshold value VT
If it is less than 2, the DC / DC converter causes normal power transmission, which will be described later, that is, power transmission from the main power storage means 1 to the auxiliary power storage means 2, and then the voltage V2 of the auxiliary power storage means 2 becomes a predetermined threshold. It is checked whether the value VT2 'has been reached. If it has been reached, the routine returns to the beginning of the routine.

In step S108, it is checked whether or not an engine start has been instructed from the vehicle control external controller (not shown). If the command has been issued, the terminal voltage V1 of the main power storage means 1 is reduced to a predetermined minimum threshold value. It is checked whether it is less than VT1. If V1 is not less than VT1, the main power storage means determines that the engine can be started and returns to the beginning of the routine.

On the other hand, if the terminal voltage V1 is lower than the predetermined minimum threshold value VT1 despite the presence of the engine start command, a reverse power transmission command to the DC / DC converter 3, which will be described later, that is, the auxiliary power storage means 2 Then, it is checked whether the voltage V1 of the main power storage means 1 has reached a predetermined threshold value VT1 '. When the voltage V1 of the main power storage means 1 reaches the predetermined threshold value VT1, the routine returns to the beginning of the routine.

In step S108, it may be determined whether or not there is a command for charging the main power storage means by a manual switch instead of the command for starting the engine. (Normal Power Transmission) Hereinafter, the normal power transmission will be described. In this normal power transmission, the relays 13 and 14 are switched to the side where the unit power storage units 11 and 12 are connected in series, and the switching elements 7a and 7b are turned off. The switches 5a and 5d are turned on and the switches 5b and 5c are turned off, and the switches 5a and 5d are turned off and the switches 5b and 5c are turned on so that the high-voltage circuit 5 performs an inverter operation. Mode is alternately repeated at a constant cycle. The voltage V2 of the auxiliary power storage means 2 may be monitored, and the duty ratio of these switches 21 to 24 may be controlled according to the magnitude, that is, the remaining amount of the auxiliary power storage means 2.

Since the secondary windings 6b and 6c are wound in opposite directions, their output terminals alternately become a positive potential and a negative potential when the lower end of the auxiliary power storage means 2 is set to 0V. Become. When the output terminals of the secondary windings 6b and 6c have a higher potential than the high-order end of the auxiliary power storage means 2, the auxiliary power storage means 2 is charged through the diodes 7c and 7d. (Reverse power transmission) The reverse power transmission from the auxiliary power storage means 2 to the main power storage means 1 will be described below.

During this reverse power transmission, the unit storage means 11, 1
2 are switched to the side where they are connected in parallel, and the switching elements 7a and 7b are turned off. Then, the low voltage circuit 7 is operated as an inverter, and the transformer 6 is operated.
The output voltage of the primary winding 6a is rectified by the high voltage circuit 5, and the main power storage means 1 connected in parallel is charged. To explain further,
By alternately intermittently switching the switching elements 7a and 7b at a predetermined cycle, current is alternately passed through the secondary windings 6b and 6c to generate an AC voltage in the primary winding 6a. This AC voltage is
Four diodes 5d bridge-connected to the high voltage circuit 5
Full-wave rectification is applied to the main power storage means 1 in 5 to 5 hours.

When the main power storage means 1 is charged so that the engine can be started by the reverse power transmission, the controller 9 stops the reverse charging operation and switches the relays 13 and 14 of the main power storage means 1 to the unit power storage means serial connection side. . Therefore, the DC voltage output from the high voltage circuit 5 is boosted approximately twice by switching the main power storage means 1, and the engine starting motor 4 can be sufficiently started.

As described above, in this embodiment, the voltage conversion ratio at the time of reverse power transmission can be increased.
Can be satisfactorily charged. Further, the main power storage means 1
Since the reverse charging is stopped when the electric power required for starting the engine is charged, unnecessary consumption of the auxiliary power storage means 2 can be prevented. In one example, the normal discharge voltage of the main power storage means is 250V, and the normal discharge voltage of the auxiliary power storage means is 1V.
2.5V, the charging voltage of the main power storage means is 300V, and the charging voltage of the auxiliary power storage means is 14.5V.

(Modification) Switching of the main power storage means 1
Although the description has been given of the single-stage serial / parallel switching, the switching may be performed by a plurality of stages.

[Brief description of the drawings]

FIG. 1 is a circuit diagram illustrating a power supply device of a hybrid electric vehicle according to a first embodiment.

[Explanation of symbols]

1 is a main storage means, 2 is an auxiliary storage means, 3 is an engine,
Is a motor for starting the engine, 5 is a high-voltage circuit (high-voltage side AC / DC conversion circuit), 6 is a transformer, 7 is a low-voltage circuit (low-voltage side AC / DC conversion circuit), 9 is a controller, 11 and 12 are unit power storage means, and 13 and 14 are 2-contact switching relay (switching means)

Claims (2)

[Claims] 1. A main power storage means having a plurality of unit power storage means and a switching means for switching the power storage means in series / parallel to supply power to at least a motor for starting an engine of a hybrid electric vehicle; A storage device, a transformer provided between the two storage devices, and a primary winding which is connected between a primary winding of the transformer and the main storage device. A high-voltage side AC / DC conversion circuit that supplies an alternating current to the line and rectifies the induced voltage of the primary winding by a rectifying element when the main storage means is charged, between the secondary winding of the transformer and the auxiliary storage means. AC power is supplied to the secondary winding by switching the switching element when the main storage means is charged, and the induced voltage of the secondary winding is regulated by the rectifier element when the auxiliary storage means is charged. A low-voltage side AC / DC conversion circuit that flows, and a control unit that controls the opening and closing of the high-voltage side AC / DC conversion circuit, the low-voltage side AC / DC conversion circuit, and the step-up switching circuit. Means for controlling the power storage means to connect the unit power storage means of the main power storage means in series, controlling the switching means at the time of charging the main power storage means, and connecting the unit power storage means of the main power storage means in parallel to the auxiliary power storage means. A power supply device for a hybrid electric vehicle, wherein each of the unit power storage means is charged by a vehicle power storage means, and each of the unit power storage means is connected in series to supply power to the engine start motor at the time of starting the engine start motor. 2. The power supply device for a hybrid electric vehicle according to claim 1, wherein said unit power storage means comprises an electric double layer capacitor.