JP3019377B2 - Voltage control device for vehicle alternator - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage control device for an AC generator for a vehicle, which uses a semiconductor element to control the energization of an exciting coil of the generator.

[Prior Art] As a conventional technique, a technique disclosed in Japanese Patent Application Laid-Open No. 64-20000 is known.

This technique reduces noise generated when a semiconductor element turns on (or turns off) an exciting coil, and a slope generation circuit that generates a gradient signal when turning on (or off) a semiconductor element; It comprises a current detection circuit for detecting the current of the element, and an arithmetic circuit for controlling the current of the semiconductor element to rise (or fall) with the gradient of the gradient signal.

[Problems to be Solved by the Invention] In the above-described technology, the circuit configurations of a slope circuit, a current detection circuit, and an arithmetic circuit are complicated. For this reason, the voltage control device of the automotive alternator shown in the prior art has a problem that the potential failure probability is high and the manufacturing cost is high.

The present invention reduces the noise generated when the excitation coil is turned on with a simple circuit configuration, reduces the probability of failure,
It is an object of the present invention to provide a vehicular AC generator voltage control device capable of reducing the manufacturing cost.

[Means for Solving the Problems] In order to achieve the above object, a voltage control device for an automotive alternator according to the present invention employs the following technical means.

[Claim 1] A voltage control device for an automotive alternator includes an exciting coil that is energized to form a magnetic field, and an armature coil that generates an electromotive force by a change in a magnetic field generated by the exciting coil. A flywheel diode connected in parallel with the coil; and a semiconductor element for interrupting power supply to the excitation coil. A drive signal is supplied to the semiconductor element to turn on the semiconductor element and supply a current to the excitation coil. And a control circuit for performing the control.

The control circuit, when turning on the semiconductor element, supplies a preliminary drive signal having a smaller driving force of the semiconductor element than the drive signal to the semiconductor element, and a voltage between the semiconductor element and the exciting coil is a predetermined value. And the drive signal is supplied to the semiconductor element after the number of times has reached.

[Claim 2] The voltage control device for an automotive alternator according to claim 1, wherein the predetermined value is a voltage indicating a state in which the flywheel diode is reversely biased.

[Claim 3] The voltage control device for an automotive alternator according to claim 1 or 2, wherein a voltage between the semiconductor element and the exciting coil is detected as a voltage between terminals of the semiconductor element. Features.

[Claim 4] The voltage control device for an automotive alternator according to claim 1 or 2, wherein a voltage between the semiconductor element and the exciting coil is detected as a voltage between terminals of the exciting coil. Features.

[Claim 5] A voltage control device for an automotive alternator is provided in an energizing path of an exciting coil to which a flywheel diode is connected in parallel, and turns on and off a semiconductor element that supplies a current to the exciting coil.

A voltage control device for the vehicle alternator, a drive signal for turning on the semiconductor element, and a drive unit for generating a preliminary drive signal having a smaller driving force of the semiconductor element than the drive signal; and the semiconductor element and the excitation. Detecting means for detecting a voltage between the coil and the coil, when the semiconductor element is turned on, after applying the preliminary drive signal from the driving means to the semiconductor element, the voltage detected by the detecting means becomes a predetermined value Switching means for providing the driving signal from the driving means to the semiconductor element when the driving signal is reached.

[Claim 6] The voltage control device for an automotive alternator according to claim 5, wherein the predetermined value is a voltage indicating a state in which the flywheel diode is reversely biased.

[Claim 7] The voltage control apparatus for an AC generator for a vehicle according to claim 5 or 6, wherein the detecting means is means for detecting a voltage between terminals of the semiconductor element.

[Claim 8] The voltage control apparatus for an AC generator for a vehicle according to claim 5 or 6, wherein the detecting means is means for detecting a voltage between terminals of the exciting coil.

[Claim 9] In the voltage control device for an automotive alternator according to any one of claims 5 to 8, the driving unit includes a driving signal generating unit that generates the driving signal, and a driving signal generating unit that generates the driving signal. And a preliminary drive signal generating means for generating the preliminary drive signal by reducing the generated drive signal by a predetermined amount.

[Claim 10] In the voltage control device for an automotive alternator according to any one of claims 5 to 8, the driving means includes: a current supply circuit (11) for supplying a predetermined current as the drive signal; A current correction circuit (32, 33, 36, 37, 38) which is reduced by a predetermined amount of current from the amount of current as the drive signal and is used as the preliminary drive signal.

[Claim 11] The voltage control device for a vehicle AC generator according to claim 10, wherein the semiconductor element is a power MOS FET.

(Claim 12) A voltage control device for a vehicle alternator includes an excitation coil,
It has a flywheel diode connected in parallel to the exciting coil, a semiconductor element provided on a current supply path from a power supply to the exciting coil, and a circuit for turning on and off the semiconductor element to control output.

A driving circuit for generating a driving signal for turning on the semiconductor element and a preliminary driving signal having a smaller driving force of the semiconductor element than the driving signal; and a voltage between the semiconductor element and the exciting coil. When the semiconductor element is turned on, the pre-driving signal is supplied to the semiconductor element, and when the voltage detected by the detection circuit reaches a predetermined value, the driving circuit outputs the semiconductor element. And a switching circuit for supplying the drive signal to the control circuit.

13. The voltage control device for an automotive alternator according to claim 12, wherein the predetermined value is a voltage indicating a state in which the flywheel diode is reversely biased.

[Claim 14] The voltage control device for an automotive alternator according to claim 12 or 13, wherein the detection circuit is means for detecting a voltage between terminals of the semiconductor element.

[Claim 15] In the voltage control device for an automotive alternator according to claim 12 or 13, the detection circuit is means for detecting a voltage between terminals of the exciting coil.

(Claim 16) The voltage control device for a vehicle AC generator according to any one of claims 12 to 15, wherein the drive circuit includes a drive signal generation circuit that generates the drive signal, and a drive signal generation circuit. A pre-driving signal generating circuit for generating the pre-driving signal by reducing the generated driving signal by a predetermined amount.

(17) The voltage control device for a vehicle AC generator according to any one of (12) to (15), wherein the drive circuit includes a current supply circuit (11) configured to supply a predetermined current as the drive signal. A current correction circuit (32, 33, 36, 37, 38) which is reduced by a predetermined amount of current from the amount of current as the drive signal and is used as the preliminary drive signal.

[Claim 18] The voltage control device for an automotive alternator according to claim 17, wherein the semiconductor element is a power MOS FET.

(Claim 19) A voltage control device for a vehicle alternator includes an excitation coil,
The flywheel diode includes a flywheel diode connected in parallel to the exciting coil, a power MOS FET provided in a current supply path from a power supply to the exciting coil, and a circuit for turning on and off the power MOS FET to control an output.

The circuit includes a determination circuit (14) for generating an ON command signal and an OFF command signal for the power MOS FET, a drive signal for turning on the power MOS FET, and a spare signal having a drive force of the power MOS FET smaller than the drive signal. A drive signal generating circuit (11, 32, 33, 3
6, 37, 38), a detection circuit (39) for detecting a voltage between the power MOS FET and the exciting coil, and receiving the ON command signal from the determination circuit to transmit the preliminary drive signal to the power MOS FET. When the voltage detected by the detection circuit reaches a voltage indicating that the flywheel diode is biased in the reverse direction, the drive signal is supplied to the power MOS FET, and an off command signal from the determination circuit is output. A switching circuit (25, 34, 35, 40) for receiving and not supplying the preliminary drive signal and the drive signal to the power MOS FET.

20. The voltage control device for an automotive alternator according to claim 19, wherein the drive signal generation circuit supplies a predetermined current as the drive signal to a gate of the power MOS FET (11). A discharge circuit (32) for forming a discharge path from the gate of the power MOS FET; and an adjustment circuit (33, 36, 37, 38) for adjusting the discharge current of the discharge circuit.

(Claim 21) In the voltage control device for a vehicle alternator according to claim 20, the switching circuit, upon receiving an ON command signal from the determination circuit, causes the current supply circuit to supply a current, A state in which the current adjusted by the adjustment circuit is discharged from the discharge circuit and applied to the power MOS FET as the preliminary drive signal, and the voltage detected by the detection circuit is biased in a reverse direction of the flywheel diode. When a voltage indicating the following is reached, the current is supplied by the current supply circuit, the discharge current is reduced by the adjustment circuit, and the reduced current is supplied to the power MOS FET as the drive signal, and when an off command signal is received from the determination circuit, The current supply by the current supply circuit is interrupted, and the current adjusted by the adjustment circuit is supplied to the discharge circuit. Wherein the discharging.

[Operation] The control circuit supplies a preliminary drive signal to the semiconductor element when the semiconductor element is turned on. The preliminary driving signal has a smaller driving force of the semiconductor element than the driving signal.

For this reason, when the semiconductor element is turned on, a suddenly large current is prevented from being supplied to the exciting coil, so that generation of a spike voltage in the armature coil is suppressed.
As a result, generation of switching noise due to the spike voltage is suppressed.

Alternatively, when a flywheel diode is provided in parallel with the excitation coil, a large current is prevented from flowing through the semiconductor element when the semiconductor element is turned on, and a large current is not supplied to the excitation coil. For this reason, the electric charge accumulated in the flywheel diode is discharged, and when the semiconductor element is turned on, the flywheel diode is prevented from being short-circuited by the recovery current. As a result, it is possible to suppress the occurrence of switching noise caused by short-circuiting of the flywheel diode.

Thereafter, when the voltage between the semiconductor element (including the power MOS FET) and the exciting coil reaches a predetermined value, the control circuit supplies a drive signal to the semiconductor element. Since the driving signal has a larger driving force of the semiconductor element than the preliminary driving signal, a large current is supplied to the exciting coil, and a large magnetic field is generated in the exciting coil.

〔The invention's effect〕

Circuit configuration that gives a preliminary drive signal with a small driving force to the semiconductor element when turning on the semiconductor element (including the power MOS FET), and the semiconductor element (including the power MOS FET)
The circuit configuration for switching from the preliminary drive signal to the drive signal when the voltage between the drive coil and the exciting coil reaches a predetermined value can be easily realized as compared with the related art.

As a result, it is possible to reduce the failure probability of the voltage control device of the automotive alternator that reduces the noise generated when the exciting coil is turned on, and to reduce the manufacturing cost.

According to the second aspect of the present invention, since the preliminary drive signal is given as a period for discharging the flywheel diode, it is possible to reliably reduce the generation of noise due to the discharge of the flywheel diode.

According to a third aspect of the present invention, the predetermined period during which the pre-driving signal is applied is set as a period until the inter-terminal voltage of the semiconductor element falls below a predetermined value. , The period between the excitation coil terminals is increased to a predetermined value or more, so that a period can be set according to the state of the circuit with a simple circuit configuration, and noise is prevented with a simple circuit configuration. be able to.

Example Next, a voltage control device for a vehicle alternator according to the present invention,
Description will be made based on one embodiment shown in the drawing.

(Structure of Embodiment) FIGS. 1 and 2 show a first embodiment of the present invention, and FIG. 1 shows an electric circuit diagram of a voltage control device of an automotive alternator.

The vehicle includes a battery 2 that supplies electric power to an electric load 1 mounted on the vehicle. The battery 2 is charged by a generator 3 driven by an engine (not shown).

The generator 3 includes an excitation coil 4 that is energized to form a magnetic field, and an armature coil 5 that generates an electromotive force due to a change in the magnetic field generated by the excitation coil 4. Is rotationally driven.
The AC current generated by the armature coil 5 is converted to DC by the rectifier circuit 6, and then output to the electric load 1 and the battery 2.

The amount of power generated by the generator 3, that is, the amount of power generated by the armature coil 5 is determined by the driving speed of the generator 3 and the energized state of the exciting coil 4. The energization state of the exciting coil 4 is controlled by the control circuit 7, and the control circuit 7 will be described below.

The control circuit 7 includes a semiconductor element 8 that interrupts the current supplied to the exciting coil 4. The semiconductor element 8 of this embodiment is an N-channel power MOS FET, and controls the current value supplied to the exciting coil 4 according to the control state of the voltage value applied to the gate. Note that the exciting coil 4 includes a flywheel diode 9 in parallel.

The gate voltage of the semiconductor element 8 is determined by a battery state determination circuit.
10, a charge pump circuit 11, and a gate discharge circuit 12.

The battery state determination circuit 10 is a circuit that detects the voltage of the battery 2 and determines whether to increase or decrease the power generation amount of the generator 3, that is, a circuit that determines whether the semiconductor element 8 is turned on or off. is there. This battery state determination circuit
The comparator 10 compares the divided voltage value of the battery voltage with the reference voltage obtained by the constant voltage circuit 13 by the comparator 14. When the battery voltage is higher than the regulation voltage, the comparator 14 outputs a Hi signal to turn off the semiconductor element 8. Conversely, when the battery voltage is lower than the regulation voltage, the comparator 14 outputs a signal of Lo so that the semiconductor element 8 is turned on. The divided voltage value of the battery voltage is determined by the resistor 15,
Obtained by 16. The constant voltage circuit 13 is a circuit that generates a constant voltage from the battery voltage supplied via the key switch 17.

The charge pump circuit 11 is a circuit that controls the gate voltage of the semiconductor element 8 according to the output of the battery state determination circuit 10, and includes a constant current supply unit 18 and a pump unit 19. The constant current supply unit 18 is a transistor that forms a current mirror circuit.
20, 21, 22 are provided. This current mirror circuit is controlled by the transistor 23. This transistor 23
Is further controlled by transistor 24. The transistor 24 is ON / OFF controlled by a signal obtained by inverting the output of the comparator 14 of the battery state determination circuit 10 by the inverter 25. Note that a constant current circuit 26 is provided in series with the transistor 24, and a current value applied to the gate of the semiconductor element 8 is controlled by a current mirror circuit. In addition, the pump section 19 is provided with an oscillation circuit 27 that constantly generates a Hi-Lo signal,
The transistor 28 to be turned off, and the transistor 28
And a capacitor 29 for storing a charge applied to the gate of the semiconductor element 8 by ON-OFF of the semiconductor element 8. Reference numerals 30 and 31 shown in the figure are diodes that prevent a backflow of current.

The gate discharge circuit 12 of the present embodiment discharges the voltage applied to the gate until the voltage between the terminals (drain-source) of the semiconductor element 8 reaches a predetermined value, and reduces the voltage applied to the gate. , Forming a preliminary drive signal. This preliminary driving signal has a very small driving force of the semiconductor element 8 as compared with a driving signal that does not discharge the charge of the gate. A transistor 32 is connected to the gate to discharge the charge of the gate. The transistor 32 forms a current mirror circuit with the transistor 33. By controlling the transistor 33, the transistor 32
32 is controlled, and the gate voltage is controlled. The transistor 33 is controlled by two transistors 34 and 35. These transistors 34 and 35 are transistors 33
The transistor 34 controls the currents of the two constant current circuits 36 and 37 to be supplied to the transistor 34. When the output of the comparator 14 of the battery state determination circuit 10 is Hi (when the semiconductor element 8 is turned off), To prevent the current of the constant current circuit 36 from being supplied to the transistor 33. The transistor 35 is turned on when the output of the comparator 14 of the battery state determination circuit 10 is Lo (when the semiconductor element 8 is turned on) and when the voltage value between the terminals of the semiconductor element 8 decreases to a predetermined value. Then, the current of the constant current circuit 37 is prevented from being supplied to the transistor 33. Reference numeral 38 denotes a diode for guiding the current of the constant current circuit 36 to the transistor 35.

In this embodiment, as means for detecting the voltage between terminals of the semiconductor element 8, the voltage between terminals of the semiconductor element 8 is detected by the voltage applied to the exciting coil 4. Specifically, the voltage between the semiconductor element 8 and the exciting coil 4 is detected by the inverter 39. That is, when the voltage applied to the exciting coil 4 is lower than the predetermined value (when the voltage between the terminals of the semiconductor element 8 does not reach the predetermined value), the inverter 39 outputs a Hi signal. When the voltage applied to the exciting coil 4 becomes higher than a predetermined value (when the voltage between the terminals of the semiconductor element 8 reaches the predetermined value), the inverter 39 outputs a signal of Lo. In this embodiment, the NOR circuit 40 is employed as a circuit for determining whether the voltage between the terminals of the semiconductor element 8 has reached a predetermined value when the semiconductor element 8 is turned on. The NOR circuit 40 outputs a signal that the battery state determination circuit 10 turns on the semiconductor element 8 and outputs the signal to the inverter 39.
When the terminal voltage reaches a predetermined value by the output of the above, a Hi signal is output to the transistor 35.

(Operation of Embodiment) Next, the operation of the above embodiment will be briefly described.

B) When the battery voltage becomes higher than the regulation voltage, the comparator 14 of the battery state determination circuit 10 generates a Hi output signal. Then, the inverter of the charge pump circuit 11
The output of 25 is inverted to Lo, and the transistor 24 is turned off. As a result, the transistors 20, 21, 22, and 23 are turned off, and the power supply to the gate is stopped.

On the other hand, the transistor 34 of the gate discharge circuit 12 is turned on in response to the Hi output of the comparator 14, and prevents the current I 2 of the constant current circuit 36 from being led to the transistor 33. Also,
The NOR circuit 40 has a transistor
35 turns off, and the current I3 of the constant current circuit 37 flows to the transistor 33.

Then, a current I3 equal to that of the constant current circuit 37 flows through the transistor 32 to discharge the gate charge. As a result, the semiconductor element 8 is turned off, the exciting current of the exciting coil 4 decreases,
The amount of power generated by the generator 3 decreases.

B) The operation in which the battery voltage is lower than the regulated voltage will be described with reference to the time chart of FIG. When the battery voltage becomes lower than the adjustment voltage (time t1), the comparator 14 of the battery state determination circuit 10 generates an output signal of Lo. Then, the output of the inverter 25 of the charge pump circuit 11 is inverted to Hi, and the transistor 24 is turned on. As a result, the transistors 20, 21, 22, and 23 are turned on, and the transistor 20,
A current I1 equal to that of the constant current circuit 26 flows through 21. Here, since the oscillation circuit 27 repeats ON-OFF, the charge pump circuit 11 supplies a current represented by the following equation to the gate.

Supply current I = I1 + C × V × f where C is the capacitance of the capacitor 29, V is the current voltage supplied to the charge pump circuit 11, and f is the pumping frequency of the oscillation circuit 27.

On the other hand, the transistor 34 of the gate discharge circuit 12 is turned off in response to the output of Lo of the comparator 14, and does not prevent the current I2 of the constant current circuit 36 from being led to the transistor 33. Also, at the beginning when the battery voltage becomes lower than the regulated voltage,
The voltage applied to the exciting coil 4 is low, and the inverter 39
Generates a Hi signal. Then, the NOR circuit 40 outputs a signal of Lo, and the transistor 35 is also turned off. As a result, the currents I2 + I3 of the constant current circuits 36 and 37 flow to the transistor 33,
As a result, the gate current becomes the supply current I− (current I2 + I3) which is the preliminary drive signal.

When the gate voltage increases and exceeds the threshold value of the semiconductor element 8 (time t2), the impedance between the terminals of the semiconductor element 8 gradually decreases, and the voltage applied to the exciting coil 4 increases. At this time, the electric charge stored in the flywheel diode 9 is discharged. When the voltage applied to the exciting coil 4 increases, the inverter 39 is inverted to Lo (time t).
3), the output of the NOR circuit 40 is inverted to Hi. Then, the transistor 35 is turned on, and the transistor 32 that has been discharging the gate is also turned off. As a result, a supply current I, which is a drive signal, is supplied from the charge pump circuit 11 to the gate. At this time, since the charge stored in the flywheel diode 9 has already been discharged, even if a large current (supply current I) is supplied from the charge pump circuit 11 to the gate, the flywheel diode 9 is not short-circuited. In addition, when a large current (supply current I) is supplied to the gate, the switching time after time t3 is short-circuited. Then, at time t4, the semiconductor element 8 is completely turned on,
The exciting current of the exciting coil 4 increases, and the amount of power generated by the generator 3 increases.

(Effects of Embodiment) As shown during the above operation, when the semiconductor element 8 is turned on, a preliminary drive signal is applied to the gate to discharge the charge of the flywheel diode 9, and then a drive signal is applied to the gate. As a result, the short-circuit of the flywheel diode 9 was prevented, and the generation of switching noise was suppressed.

The circuit configuration of the control circuit 7 of the present embodiment is simpler than that of the related art. As a result, the failure probability of the control circuit 7 can be reduced as compared with the related art, and the manufacturing cost can be reduced.

(Second Embodiment) FIG. 3 is an electric circuit diagram of a voltage control device of an automotive alternator according to a second embodiment. The same reference numerals as those in the first embodiment indicate the same functional objects.

In the present embodiment, a P-channel power MOS
It uses FET. Therefore, in this embodiment, the charge pump circuit shown in the first embodiment is not required.

The operation when the semiconductor element 8 is turned on will be briefly described.

When the battery voltage becomes lower than the adjustment voltage, the comparator 14 of the battery state determination circuit 10 generates an output signal of Lo. Then, the transistors 20 and 24 are turned off, and supply of current to the gate is stopped.

On the other hand, at the initial stage when the battery voltage becomes lower than the regulated voltage, the voltage applied to the exciting coil 4 is low,
39 generates a Hi signal. Then, the transistor 34 of the gate discharge circuit 12 is turned on in response to the Hi output of the inverter 39, and prevents the current I2 of the constant current circuit 36 from being guided to the transistor 33. For this reason, only the current I3 of the constant current circuit 37 flows through the transistor 33, and as a result, the current I3
And the semiconductor element 8 starts to turn on.

Then, when the gate voltage rises and is inverted to Lo of the inverter 39, the transistor 34 is turned off, and the constant current circuits 36 and 37 are turned off.
Currents I2 and I3 are guided to the transistor 33. As a result,
The gate is discharged by the current I2 + I3, the semiconductor element 8 is rapidly turned on, and the exciting coil 4 is energized.

When the battery voltage becomes higher than the regulated voltage, the comparator 14 of the battery state determination circuit 10 generates a Hi output signal, the transistors 20 and 24 are turned on, and a current is supplied to the gate. Further, the transistor 35 is turned on, and the discharge of the gate by the gate discharge circuit 12 is stopped. As a result, the gate is charged, the semiconductor element 8 is turned off, and the energization of the exciting coil 4 is stopped.

(Modification) Although an example has been shown in which the preliminary drive signal is formed by partially discharging the drive signal applied to the semiconductor element, the voltage value or the current value supplied to the semiconductor element may be switched and applied.

Although an example in which an FET is used as a semiconductor element has been described, another element such as a bipolar transistor may be used.

The electric circuit is not limited to the circuit configuration of this embodiment, and other circuit configurations such as controlling a drive signal and a preliminary drive signal by a microcomputer may be adopted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 and FIG. 2 show a first embodiment of the present invention. FIG. 1 is an electric circuit diagram of a voltage control device of a vehicle AC generator, and FIG. It is a time chart for explanation. FIG. 3 is an electric circuit diagram of a voltage control device for a vehicle AC generator according to a second embodiment of the present invention. In the figure, 3 ... a generator, 4 ... an exciting coil 5 ... an electronic machine coil, 7 ... a control circuit 8 ... a semiconductor element

Claims (21)

(57) [Claims] 1. A voltage control device for an automotive alternator comprising: an excitation coil that is energized to form a magnetic field; and an armature coil that generates an electromotive force by a change in a magnetic field generated by the excitation coil. A flywheel diode connected in parallel to the excitation coil; and a semiconductor element for interrupting power supply to the excitation coil. A drive signal is supplied to the semiconductor element to turn on the semiconductor element, and a current is supplied to the excitation coil. A voltage control device for an automotive alternator including a control circuit that supplies a preliminary drive signal having a smaller driving force of the semiconductor element than the drive signal when the semiconductor element is turned on. And applying the drive signal to the semiconductor element after the voltage between the semiconductor element and the exciting coil reaches a predetermined value. Voltage control apparatus for a vehicle alternator according to claim. 2. The voltage control device according to claim 1, wherein the predetermined value is a voltage indicating a state in which the flywheel diode is reversely biased. 3. The voltage control of a vehicle AC generator according to claim 1, wherein a voltage between the semiconductor element and the exciting coil is detected as a voltage between terminals of the semiconductor element. apparatus. 4. The voltage control of a vehicle AC generator according to claim 1, wherein a voltage between the semiconductor element and the exciting coil is detected as a voltage between terminals of the exciting coil. apparatus. 5. A voltage control device for an automotive alternator, wherein a flywheel diode is provided in an energizing path of an exciting coil connected in parallel and turns on and off a semiconductor element for supplying a current to the exciting coil. Drive means for generating a drive signal for turning on the semiconductor element, a preliminary drive signal having a smaller driving force of the semiconductor element than the drive signal, and detection means for detecting a voltage between the semiconductor element and the exciting coil. When the semiconductor element is turned on, after the preliminary driving signal is supplied from the driving means to the semiconductor element, when the voltage detected by the detecting means reaches a predetermined value, the driving means transfers the semiconductor element to the semiconductor element. A voltage control device for an AC generator for a vehicle, comprising: switching means for providing a drive signal. 6. The voltage control device according to claim 5, wherein the predetermined value is a voltage indicating a state in which the flywheel diode is reversely biased. 7. The voltage control device for an automotive alternator according to claim 5, wherein said detecting means is means for detecting a voltage between terminals of said semiconductor element. 8. The voltage control device for an automotive alternator according to claim 5, wherein said detection means is means for detecting a voltage between terminals of said exciting coil. 9. A driving signal generating means for generating the driving signal, and a pre-driving means for generating the pre-driving signal by reducing the driving signal generated by the driving signal generating means by a predetermined amount. The voltage control device for a vehicle AC generator according to any one of claims 5 to 8, further comprising signal generation means. 10. A driving circuit comprising: a current supply circuit for supplying a predetermined current as the driving signal; and a pre-driving signal by reducing a current amount as the driving signal by a predetermined current amount. Current correction circuit (32, 33, 36, 37, 3
The voltage control device for an AC generator for a vehicle according to any one of claims 5 to 8, further comprising (8). 11. The voltage control device for an automotive alternator according to claim 10, wherein said semiconductor element is a power MOS FET. 12. An exciting coil, a flywheel diode connected in parallel to the exciting coil, a semiconductor element provided in a current supply path from a power supply to the exciting coil, and an output by turning on and off the semiconductor element. A drive circuit for generating a drive signal for turning on the semiconductor element and a preliminary drive signal having a smaller driving force for the semiconductor element than the drive signal. A detection circuit for detecting a voltage between the semiconductor element and the exciting coil; and a voltage detected by the detection circuit after supplying the preliminary drive signal to the semiconductor element when the semiconductor element is turned on. And a switching circuit for supplying the drive signal from the drive circuit to the semiconductor element when a predetermined value is reached. Voltage control device. 13. The voltage control device for an automotive alternator according to claim 12, wherein said predetermined value is a voltage indicating a state in which said flywheel diode is reversely biased. 14. The device according to claim 12, wherein said detection circuit is means for detecting a voltage between terminals of said semiconductor element.
14. A voltage control device for a vehicle alternator according to item 13. 15. The apparatus according to claim 12, wherein said detection circuit is means for detecting a voltage between terminals of said exciting coil.
14. A voltage control device for a vehicle alternator according to item 13. 16. A drive signal generating circuit for generating the drive signal, and a preliminary drive for generating the preliminary drive signal by reducing the drive signal generated by the drive signal generating circuit by a predetermined amount. 16. The voltage control device for a vehicle AC generator according to claim 12, further comprising a signal generation circuit. 17. The drive circuit, comprising: a current supply circuit for supplying a predetermined current as the drive signal; and a pre-drive signal by reducing a current amount as the drive signal by a predetermined current amount. Current correction circuit (32, 33, 36, 37, 3
16. The voltage control device for an automotive alternator according to claim 12, wherein the voltage control device comprises: 18. The voltage control device for an automotive alternator according to claim 17, wherein said semiconductor element is a power MOS FET. 19. An exciting coil, a flywheel diode connected in parallel to the exciting coil, and a power MOS FET provided in an energizing path from a power supply to the exciting coil.
And a circuit for controlling the output by turning on and off the power MOS FET, wherein the circuit includes a determination circuit (14) for generating an ON command signal and an OFF command signal for the power MOS FET. ), And a drive signal generation circuit (11, 32, 33, 36, 36) for generating a drive signal for turning on the power MOS FET and a preliminary drive signal having a drive force of the power MOS FET smaller than the drive signal.
37, 38), a detection circuit (39) for detecting a voltage between the power MOS FET and the exciting coil, and receiving an ON command signal from the determination circuit to provide the preliminary drive signal to the power MOS FET. Further, when the voltage detected by the detection circuit reaches a voltage indicating a state in which the flywheel diode is biased in the reverse direction, the drive signal is supplied to the power MOS FET, and an OFF command signal from the determination circuit is received. A switching circuit (25, 34, 35, 40) for preventing the pre-driving signal and the driving signal from being supplied to the power MOS FET. 20. A power supply circuit comprising: a current supply circuit for supplying a predetermined current as the drive signal to the gate of the power MOS FET; and a discharge circuit for forming a discharge path from the gate of the power MOS FET. 32) and an adjustment circuit (33, 36, 37, 38) for adjusting the discharge current of the discharge circuit
20. The voltage control device for an AC generator for a vehicle according to claim 19, comprising: 21. The switching circuit, upon receiving an ON command signal from the determination circuit, causes the current supply circuit to supply current and discharges the current adjusted by the adjustment circuit from the discharge circuit. When the voltage detected by the detection circuit reaches a voltage indicating that the flywheel diode is reversely biased, the current is supplied by the current supply circuit. Reducing the discharge current by the adjustment circuit, applying the reduced discharge current to the power MOS FET as the drive signal, and receiving an OFF command signal from the determination circuit, interrupting the current supply by the current supply circuit and adjusting the current supply circuit. 21. The vehicle AC generator according to claim 20, wherein the discharged current is discharged from the discharge circuit. Electric motor voltage controller.