JPH0568350A - Power supply device for vehicle - Google Patents

Abstract

PURPOSE:To eliminate the application of overvoltage to a battery or an electric load by preventing a generator from overgenerating. CONSTITUTION:In a generator 4, a shorting circuit 6 which shorts the current generated by an armature coil 7 is provided. The shorting circuit 6 is provided with a command circuit 17 which, detecting the conduction state of a field magnetic coil 8, gives a shorting instruction, and a shorting circuit 18 having a thyristor trio 22 which, receiving the shorting instruction, shorts the armature coil 7 when the battery voltage is the specified value or above. When the battery voltage increases and the conduction of the field magnetic coil 8 stops or decreases, the command circuit 17 gives the shorting instruction to the shorting circuit 18. Then, the thyristor trio 22 of the shorting circuit 18 is turned ON and thereby excess current generated by the armature coil 7 is shorted and consequently, the generator 4 is prevented from overgenerating.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle power supply device using a generator that controls the amount of electricity supplied to a field winding to adjust the amount of power generation.

[0002]

2. Description of the Related Art A generator driven by an engine is
In recent years, it has been required that the driving torque of the generator does not suddenly increase or decrease even if the electric load suddenly increases or decreases. Therefore, there is known a gradual increase control method in which the energization amount (excitation current) of the armature winding is gradually increased when the electric load is rapidly increased. However, there is currently no way to deal with a sudden decrease in electrical load.

[0003]

This is because when the amount of electricity to the field winding is gradually reduced when the electric load is suddenly reduced, the armature winding of the generator generates excessive electric power that exceeds the demand of the electric load. Will end up. Then, if this excess power is absorbed by the vehicle-mounted battery, there is a problem that the life of the battery is significantly shortened.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a vehicle power supply device which does not supply excess power to a battery or an electric load even if the armature winding of a generator generates excess power.

[0005]

SUMMARY OF THE INVENTION In a vehicle power supply device of the present invention, the amount of electricity supplied to a battery connected to an electric load and the field winding is controlled to adjust the electric power generated by the armature winding. A generator that supplies the electric power to the battery,
A technical means including a short circuit that short-circuits the current generated by the generator according to the battery state is adopted.

[0006]

When the armature winding of the generator generates excessive electric power due to a sudden decrease in electric load and a gradual decrease in the amount of electric current flowing through the field winding, the battery state changes. The short-circuit circuit short-circuits the current generated by the generator when excessive power generation of the armature winding is detected from the battery state, and prevents excessive voltage from being applied to the battery or electric load.

[0007]

As has been described above, the electric power supply system for a vehicle according to the present invention causes the current generated by the generator to be short-circuited even if the armature winding of the generator generates excessive electric power. Do not supply excessive power to batteries or electrical loads. As a result,
It is possible to eliminate problems caused by the application of excessive voltage to the battery and the electric load.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a vehicle power supply device of the present invention will be described based on an embodiment shown in the drawings. [Configuration of Embodiment] FIG. 1 is an electric circuit diagram of a vehicle power supply device showing an embodiment of the present invention. The vehicle power supply device includes a battery 3 (for example, a rated voltage of 12V) that is a vehicle power source connected to an electric load 1 of the vehicle such as a light via a switch 2, and an alternating current that supplies electric power to the electric load 1 and the battery 3. It is composed of a generator 4, a regulator 5 that controls the power generated by the generator 4, and a short circuit 6 that short-circuits the current generated by the generator 4 according to the battery state.

The generator 4 is a well-known one having a Y-connected armature winding 7 and a field winding 8, and the field winding 8 is energized so that one of the armature winding 7 and the field winding 8 is energized. The motor is driven to rotate by the engine to generate electric power in the armature winding 7. The electric power generated in the armature winding 7 is rectified by the rectifier circuit 9 and supplied to the battery 3 and the electric load 1.

The regulator 5 of this embodiment is composed of the field winding 8
The duty ratio is controlled according to the battery voltage and the voltage generated by the generator 4. Specifically, the regulator 5 has a comparison unit 11 that compares whether or not the battery voltage or the generated voltage of the generator 4 is a reference stored in the reference voltage unit 10, and according to the difference between the reference voltages. It has a duty ratio controller 12 that determines the duty ratio. The duty ratio control unit 12 compares the Hi time of the PWM signal generated by the PWM carrier generation unit 13 with the comparison unit 11
The signal is changed in accordance with the signal No., and is set so as to gradually increase when the duty ratio is increased.
Further, when the duty ratio is reduced, the duty ratio is gradually reduced or abruptly becomes zero according to the signal from the comparison unit 11. Even if the duty ratio is suddenly reduced to zero, the current flowing through the flywheel diode 14 connected to the field winding 8 does not drastically reduce the energization amount of the field winding 8. The duty ratio determined by the duty ratio controller 12 is received by the base controller 15, and the winding energizing transistor 16 (semiconductor switching element) connected to the field winding 8 is drive-controlled to drive the field winding 8. Control the energization amount of.

The short circuit 6 comprises a command circuit 17 for detecting a battery state and giving a short circuit instruction, and a short circuit execution circuit 18 for short circuiting the current generated by the generator 4 in response to the short circuit instruction. In the present embodiment, the command circuit 17 detects a duty ratio, which is a control of the energization amount of the field winding 8, as means for detecting the battery state. Specifically, a duty-zero detector 19 for detecting that the duty ratio has become zero, and a duty gradual decrease detector 20 for detecting that the duty ratio gradually decreases are provided, and a short circuit occurs when one of them is detected. The base drive unit 21 gives an instruction (a signal for turning on a gate control transistor described below). The short-circuit execution circuit 18 includes a thyristor trio 22 connected to each field winding 8 as a means for short-circuiting the current generated by the generator 4 in order to short-circuit the current generated in the field winding 8. The thyristor trio 22 is turned on and off by the gate control circuit 23. The gate control circuit 23 gives a signal to turn on the thyristor to each gate of the thyristor trio 22 according to the short circuit instruction from the command circuit 17 and the battery voltage. For example, the short circuit instruction is given and the battery voltage is 14V. At the above time, the thyristor 22 is turned on. Specifically, the gate control circuit 23 includes a gate control transistor 24 and a Zener diode 2 for adjusting a short circuit voltage.
5 and a plurality of current limiting resistors 26. Note that the gate control transistor 24 has a V _CE of about 1.5 V,
Even if the Zener voltage of the Zener diode 25 is set to about 12.5V and the gate control transistor 24 is turned on, if the battery voltage is 14V or less, the thyristor trio 22
Is provided so that does not turn on.

[Operation of Embodiment] Next, the operation of the above embodiment will be briefly described. When the switch 2 is turned on and the electric load 1 of the vehicle is large, the electric load 1 tends to consume a large amount of electric power stored in the battery 3. Then, the regulator 5 increases the duty ratio of the regulator 5 to compensate for the decrease in the battery voltage, lengthens the ON time of the winding energizing transistor 16, and causes a relatively large exciting current to flow in the field winding 8. Keep the battery voltage in the proper range (eg 12-14.5V).

Next, when the switch 2 is turned off,
When the electric load 1 suddenly decreases, the power consumption stored in the battery 3 decreases and the battery voltage rises.
Then, the regulator 5 sets the duty ratio to zero and turns off the winding energizing transistor 16 in order to prevent the generator 4 from generating extra power. However, due to the inductance of the field winding 8, the exciting current circulates via the flywheel diode 14, and the amount of electricity supplied to the field winding 8 gradually decreases. Immediately after switch 2 is turned off,
Despite the rapid decrease in battery 3 consumption
Since the voltage generated by the generator 4 gradually decreases, the generator 4 performs excessive power generation. As described above, when the generator 4 performs excessive power generation, the duty ratio of the regulator 5 becomes zero or decreases. Therefore, the change of the duty ratio is detected by the zero duty detecting unit 19 and the gradually decreasing duty detecting unit of the short circuit 6. The gate control transistor 24 is detected, and a short circuit instruction is given to the gate control transistor 24 to turn on the gate control transistor 24. And
When the battery voltage exceeds 14V due to the excessive power generation of the generator 4, the thyristor 22 is turned on, and the excess current generated in the armature winding 7 is short-circuited and released to the ground. As a result, the generator 4 Is maintained at 14V.

[Effects of the Embodiment] Even if the electric load 1 is suddenly reduced, the amount of electricity supplied to the field winding 8 of the generator 4 is gradually reduced, so that the driving torque of the generator 4 is rapidly reduced. Is eliminated. Further, even if the electric load 1 suddenly decreases, the amount of current flowing through the field winding 8 of the generator 4 gradually decreases, so that the armature winding 7 of the generator 4 generates excessive power, but the short circuit Excessive power is released by 6. Therefore, the voltage generated by the generator 4 is maintained at 14 V, which is within the proper range of the battery 3. In other words, since high voltage is prevented from being applied to the battery 3 and the electric load 1, problems such as shortening the life of the battery 3 and increasing the failure probability of the electric load 1 due to the high voltage being applied. It can be lost.

[Modification] In the above embodiment, an example in which a thyristor is used as a means for short-circuiting the electric power generated by the generator is shown. However, other semiconductor elements such as a transistor,
Other short-circuiting means such as switching control of a contact switch may be used. Although the current generated by the generator is short-circuited by short-circuiting the current generated by the armature winding, the current generated by the generator can be reduced by short-circuiting the battery or the current applied to the battery. You may short-circuit. By providing the current applied to the battery so as to be short-circuited in accordance with the battery voltage, when the battery mounted on the vehicle is connected to another battery, the voltage applied to the battery is excessive and The electric load can be protected. Although the example in which the state of the battery at the time of excessive power generation is detected by using the duty ratio is shown, the excessive power generation of the generator may be detected from other battery states such as by detecting the battery voltage.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a vehicle power supply device.

[Explanation of symbols]

 1 Electric Load 3 Battery 4 Generator 6 Short Circuit 7 Armature Winding 8 Field Winding

Claims (1)

[Claims] 1. A battery connected to an electric load, a generator that controls the amount of electricity supplied to a field winding to adjust the electric power generated by an armature winding, and supplies the generated electric power to the battery, and the battery. A power supply device for a vehicle, comprising: a short circuit that short-circuits a current generated by the generator according to a state.