JPH08140284A - Voltage controller of generator for vehicle - Google Patents

Abstract

PURPOSE: To provide an inexpensive device which suppresses the drop of voltage at switching in of an electric load, and prevents the hunting at idling. CONSTITUTION: This is equipped with a switching detecting circuit 30, which detects the connected electric load 6, and an exciting current control circuit 40, which changes over the increase speed of the exciting current of a three- phase AC generator 1, and in the case that electric load is not detected, this lowers the increase speed of the exciting current, and in the case that the electric load is detected, this raises the increase speed of the exciting current. When the electric load is not connected, hunting does not occur since the increase of the load of the three-phase AC generator 1 s slow. At when switching in the electric load, the voltage drop of a battery 5 is small since the exciting current is increased quickly. Since it is necessary only to detect whether the electric power is made or not, the circuit constitution can be simplified, and this can be made an inexpensive device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage control device for a vehicle alternator for controlling an output voltage of a generator driven by an engine by controlling an exciting current.

[0002]

2. Description of the Related Art In a voltage control device for a generator, in order to prevent hunting during idling, Japanese Patent Laid-Open No. 54-7111.
Japanese Patent Laid-Open No. 58-19249, in which the adjustment voltage of the generator is changed according to the differential value of the rotation speed of the generator.
By fixing the exciting current drive duty ratio at a duty ratio according to the absolute amount of the electric load as in No. 9,
There is one that prevents a battery voltage drop when an electric load is applied and also prevents hunting when idle.

[0003]

However, in the former case, since the battery voltage is greatly reduced after the electric load is applied, the brightness of the lamps of the vehicle and the change of the blower sound may occur, and the other of the vehicle may be changed. There is a possibility of causing malfunction of the electric equipment, and in the latter case, there is a problem that it is necessary to grasp the absolute amounts of all electric loads, which causes a significant increase in cost.

It is an object of the present invention to provide an inexpensive device which can suppress a voltage drop when an electric load is applied and can prevent hunting at idle.

[0005]

According to a first aspect of the present invention, an electric load is provided in a voltage control device for controlling an exciting current so that a generated voltage of an AC generator driven by a vehicle engine has a set value. It is provided with a load closing detection means for detecting closing and an exciting current control means for switching an increasing speed of the exciting current of the AC generator, and the exciting current control means does not detect the electric load closing by the load closing detection means. In this case, the increasing speed of the exciting current is reduced, and when the electric load applying is detected by the load applying detecting means, the increasing speed of the exciting current is kept constant for a certain period of time after the electric load applying is detected. It is a technical means to make the voltage larger than that before the electric load is applied, or until the generated voltage becomes again the set value or more after the detection of the electric load.

According to a second aspect of the present invention, the technical means according to the first aspect is to increase the set value of the generated voltage of the AC generator when increasing the increasing rate of the exciting current. According to a third aspect of the present invention, in the first or second aspect, the load input detecting means is technically configured to detect the electric load input when the differential value of the voltage decrease amount of the vehicle battery is equal to or more than a predetermined value. Use it as a means.

According to a fourth aspect of the present invention, the technical means according to the first aspect is that the control operation is performed at least when the vehicle engine is idle.

[0008]

In the present invention, the exciting current control means for switching the increasing speed of the exciting current of the generator is provided, and the increasing speed of the exciting current is controlled to be small when the electric load is not detected. . As a result, when the engine speed decreases due to the load fluctuation of the vehicle engine, and the generator output decreases, the exciting current is gradually increased, so that the engine load may rapidly increase. Absent. Therefore, fluctuations in the engine speed can be reduced and hunting can be prevented. When the application of the electric load is detected, the increasing rate of the exciting current is controlled to increase. As a result, even if the battery voltage sharply drops due to the application of an electric load, the exciting current is rapidly increased and the generator output increases, so that the battery voltage does not drop significantly and the battery can be immediately recovered.

[0009]

According to the first aspect of the present invention, when the electric load application is not detected, the increasing speed of the exciting current is controlled so as to be small, so that the load of the engine for driving the generator is reduced. It does not grow suddenly and hunting does not occur. Further, when the electric load is applied, the output of the generator can be rapidly increased, so that the battery voltage drop can be prevented, and the fluctuation of the brightness of the lamps and the fluctuation of the blower sound do not occur. As a means for these operations, it is not necessary to grasp the absolute amount of the electric load, and any device capable of detecting the electric load application can be used. Can be realized.

According to the second aspect of the present invention, the set value of the power generation voltage of the AC generator is increased when the rate of increase of the exciting current is increased, so that the output voltage of the generator can be increased when the electric load is turned on. Therefore, the range of decrease in the battery voltage can be further reduced. According to claim 3, since the load application is detected when the differential value of the voltage drop of the vehicle battery is equal to or greater than a predetermined value, the circuit configuration for load application detection can be simplified and the apparatus is inexpensive. You can According to the fourth aspect, at least the control is performed at the time of idling when the engine speed is kept constant, so that hunting in the engine idle control can be reliably prevented. In addition, since it is possible to reduce the decrease in the battery voltage at the time of idling, in which variations in the brightness of the lamps and variations in the blower sound are easily recognized, the user does not feel uncomfortable.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a voltage control device for a vehicle AC generator of the present invention will be described based on the embodiments shown in the drawings. In FIG. 1, 1 is a three-phase AC generator driven by a running engine mounted on a vehicle, 2 is an armature winding of the three-phase AC generator 1, and 3 is an AC generated in the armature winding 2. Rectifier 4 for full-wave rectifying the output is a field winding. Reference numeral 5 is a battery mounted on the vehicle, 6 is an electric load of the vehicle, and 7 is a key switch.

Reference numeral 10 is a voltage controller for controlling the exciting current of the field winding 4 by controlling the switching of the switching element 11 to adjust the generator output and the voltage of the battery 5 to set values, and 12 is a key switch. A power supply circuit for supplying a battery voltage source supplied via 7 to each circuit, 13
Is a freewheeling diode of the field winding 4. In the voltage control device 10, a voltage control signal generation circuit 20 detects a battery voltage and outputs a voltage control signal for controlling the generator output voltage to the excitation current control circuit 40. 30
Is a load application detection circuit, which detects the application of the electric load 6 from the time change of the battery voltage via the voltage control signal generation circuit 20, and outputs the load application signal to the excitation current control circuit 40. The excitation current control circuit 40 outputs a drive signal for driving the switching element 11 based on the voltage control signal and the load input signal.

Hereinafter, each circuit 20 in the voltage control device 10,
30 and 40 will be described with reference to the drawings. In the figure, 100 to 106 are terminals for connecting each circuit. In the voltage control signal generation circuit 20 shown in FIG.
The terminal voltage of the battery 5 applied via the terminal 100 is divided by the resistors 200 and 201, and the capacitor 202
To form a smoothing circuit. Also, the resistors 203, 20
4 and the operational amplifier 205 constitute a differential amplifier. Reference numeral 206 denotes a reference voltage generation circuit that generates a reference voltage 206E corresponding to the generator regulated voltage.
Is an oscillation circuit that determines the switching frequency of the switch element 11 that drives the excitation current, 208 is a sawtooth wave generation circuit that generates a sawtooth wave in synchronization with the oscillation signal of the oscillation circuit 207, 20
Reference numeral 9 is a comparator that compares the output of the operational amplifier 205 and the output of the sawtooth wave generation circuit 208 and outputs a PWM signal 209E.

In the load-on detection circuit 30 shown in FIG. 3, resistors 301 and 302 divide the output voltage 205E of the operational amplifier 205 of the voltage control signal generation circuit 20 provided via the terminal I101. The analog switch composed of the inverter 303 and the gate 304 is connected to the terminal 10
The output voltage 205E of the operational amplifier 205 is supplied to the capacitor 305 in accordance with the oscillation signal of the oscillation circuit 207 of the voltage control signal generation circuit 20 given via the circuit 4. The comparator 306 uses the divided voltage 3 by the resistors 301 and 302.
02E and the terminal voltage 305E of the capacitor 305 are compared, and when the output 306E is Hi, the flip-flop 3
Set 07. The flip-flop 307 has a terminal 1
02 is reset when the PWM signal 209E of the output of the comparator 209 of the voltage control signal generation circuit 20 is Hi, and the output of the flip-flop 307 is supplied to the excitation current control circuit 40.

In the exciting current control circuit 40 shown in FIG. 4, the PW of the output of the comparator 209 of the voltage control signal generation circuit 20 supplied from the terminal 102 via the limiting resistor 401.
The duty ratio of the M signal 209E is stored in the capacitor 404 via the analog switch including the inverter 402 and the gate 403. Reference numeral 405 denotes a limited duty pulse generation circuit, and the AND circuit 406 to which the output of the limited duty pulse generation circuit 405 is input is the terminal 1 on the other hand.
05, the output of the flip-flop 307 of the load-on detection circuit 30 is input via the inverter 407, and the output thereof causes the inverter 402 and the gate 4
Control the analog switch consisting of 03. A buffer 408 outputs the voltage of the capacitor 404.

The resistor 409 and the constant current circuit 410 constitute a level shift circuit which operates when the analog switch composed of the inverter 411 and the gate 412 is closed. The comparator 413 compares the stored value of the capacitor 404 or a value level-shifted from the stored value with the sawtooth wave voltage 208E of the sawtooth wave generation circuit 208 of the voltage control signal generation circuit 20, and the output PWM signal 413E is the AND circuit. 414 is input. The AND circuit 414 is a PWM
The PWM signal 209E which is the output of the comparator 209 of the voltage control signal generation circuit 20 is input together with the signal 413E, and the output thereof is given to the switching element 11 via the buffer 415.

Next, the operation of the voltage control device 10 of the present embodiment having the above configuration will be described. First, the basic operation of voltage control will be described with reference to FIG. When the key switch 7 is turned on, power is supplied to the power supply circuit 12, and a predetermined voltage is supplied to each circuit. In the voltage control signal generation circuit 20, the terminal voltage of the battery 5 is input via the terminal 100, and the divided and smoothed divided voltage 201E is compared with the reference voltage 206E of the reference voltage generation circuit 206.
The difference voltage is inverted and amplified by the operational amplifier 205. The output voltage 205E of the operational amplifier 205 is the sawtooth wave voltage 208E of the sawtooth wave generation circuit 208 in the comparator 209.
In comparison with the battery voltage, the comparator 209 outputs the PWM signal 209E having a larger duty ratio as the battery is lower and a duty ratio as the battery is higher, as a voltage control signal.

The excitation current control circuit 40 receives the PWM signal 209E, and integrates the voltage 409E with an integrating circuit having a time constant sufficiently longer than the PWM signal 209E.
And the sawtooth voltage 208E are compared by the comparator 413,
The PWM signal 413E and the PWM signal 209 which are the outputs
An AND logic with E is obtained by an AND circuit 414, and the switching element 11 is intermittently controlled by its output.

In the steady state, the PW of the comparator 413 is
The M signal 413E is P which is the output of the comparator 209.
Since it is the same as WM209E, the switching element 11 is intermittent at the duty ratio of the PWM signal 209E. Therefore, when the battery voltage decreases with respect to the set voltage based on the reference voltage 206E, the duty ratio of the PWM 209E increases and the exciting current increases, so that the generator output increases and the battery voltage increases. On the contrary, when the battery voltage becomes higher than the set voltage, the exciting current decreases, so the generator output decreases and the battery voltage decreases. Since these operations are repeated, the battery voltage is controlled near the set voltage.

Next, the hunting prevention mode and the electric load input response mode, which are operation modes in the transient operation of the voltage control device 10, will be described. Hunting prevention mode When idling and when the electrical load is constant, the battery voltage is relatively stable, and the output 205 of the operational amplifier 205
E also has little fluctuation. Therefore, the output 205E is connected to the resistor 30.
The result obtained by comparing the divided voltage 302E divided by 1 and 302 and the terminal voltage 305E of the capacitor 305, which periodically stores the output 205E by the output 207E of the oscillation circuit 207, by the comparator 306 is always the Lo output and the flip-flop. The Q output 307E of the driver 307 also becomes Lo, which means that the load application is not detected.

As a result, the output of the AND circuit 406 of the exciting current control circuit 40 becomes the output of the limited duty pulse generation circuit 405, and the inverter 402 and the gate 40.
By controlling the analog switch composed of 3 to reduce the conduction rate of the gate 403, the time constant of the integrating circuit increases. Further, since the gate 412 is also turned off, the level shift circuit does not operate, so that the terminal voltage of the capacitor 404 becomes the input of the comparator 413 as it is. Therefore, in the steady state, the output of the comparator 413 is the same as the voltage control signal 209E, but is a PWM signal with a small temporal change rate of the duty ratio.

In this state, if the engine speed is slightly reduced due to the change of the mechanical load of the engine, the output of the generator is reduced and the battery voltage is slightly reduced. Therefore, the duty ratio of the voltage control output signal 209E immediately increases, but the output signal 413 of the comparator 413 increases.
The duty of E is gradually increased (for example, 20
S / 100%). Therefore, the increase in the generator output torque due to the increase in the generator output is performed very gradually. As a result, the engine speed increases again due to the operation of the ISC (idle speed control device) and stabilizes at the set speed.

If the switching element 11 is controlled not by the output of the AND circuit 414 but only by the voltage control signal 209E, the generator output rapidly increases.
The generator driving torque rapidly increases and the engine speed further decreases. This torque rapid increase is 100 to 200 mS.
It occurs at the time of, and is faster than the control speed of ISC (about 500 mS). Therefore, since the ISC control is always delayed, the engine speed becomes unstable and hunting occurs. The control according to the present invention does not cause a sudden increase in the generator driving torque, so that there is no such problem and hunting can be prevented.

Electric Load Input Response Mode When an electric load is input, the battery voltage instantaneously greatly drops. Therefore, the output 205 of the operational amplifier 205
E increases instantly. This output 205E divided voltage 3
02E is compared with the terminal voltage 305E of the capacitor 305, that is, the value of the output 205E before the electric load is turned on, the divided voltage 302E is larger, so the output 306E of the comparator 306 becomes Hi and the flip-flop 307 is set. Then, the Q output 307E becomes Hi.

Therefore, the output 406E of the AND circuit 406 of the exciting current control circuit 40 becomes Lo and the gate 403 is turned on. This reduces the time constant of the integrating circuit. Since the gate 412 is also turned on, the level shift circuit operates to shift the output value of the integration circuit by several%. Therefore, when the electrical load is turned on, the O output 307E which is the voltage control signal instantaneously becomes 100% duty, but the PWM signal 413E which is the output of the comparator 413 has a duty ratio of several% from the same duty ratio as the PWM signal 209E. After the ratio increases sharply, it increases at a relatively fast speed (5S / 100%).

Since the drive signal 106E which is the output of the exciting current control circuit 40 becomes the same signal as that of the comparator 413, the exciting current increases by several% when an electric load is applied, and
Increases at a relatively fast speed. When the electric load is turned on by such an operation, the exciting current increases at a faster speed than in the hunting mode, so that the generator output increases relatively quickly, and the voltage drop of the battery voltage after the electric load is turned on and The fall time can be shortened, and malfunctions of other electronic devices and light and dark of lamps can be prevented.

The load input detection circuit 30 may be a circuit for detecting that the voltage is lower than the set voltage of the generator output. Further, the detection of the electric load can be detected from the electric load switch, or the electric load current or the battery current can be measured and detected using a shunt resistor or a Hall element. Further, the voltage control signal generation circuit 20
When the load application is detected, the reference voltage 206E of the reference voltage generation circuit 206 may be changed to a higher value.

[Brief description of drawings]

FIG. 1 is a block diagram of a voltage control device for a vehicle AC generator showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a voltage control signal generation circuit of this embodiment.

FIG. 3 is a circuit diagram showing a load-on detection circuit of this embodiment.

FIG. 4 is a circuit diagram showing an exciting current control circuit of the present embodiment.

FIG. 5 is a voltage waveform diagram for explaining the basic operation of the voltage control device according to the present embodiment.

FIG. 6 is a voltage waveform diagram for explaining a hunting prevention mode of the voltage control device according to the present embodiment.

FIG. 7 is a voltage waveform diagram for explaining an electric load closing response mode of the voltage control device according to the present embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Three-phase AC generator 5 Battery 6 Electric load 10 Voltage control device 30 Load application detection circuit (load application detection means) 40 Excitation current control circuit (excitation current control means)

Claims (4)

[Claims] 1. A voltage control device for controlling an exciting current so that a generated voltage of an alternator driven by a vehicle engine has a set value, and load applying detection means for detecting electric load application; Exciting current control means for switching the increasing speed of the exciting current of the machine, the exciting current control means reduces the increasing speed of the exciting current when the electric load application is not detected by the load application detecting means. When the electric load input is detected by the load input detecting means, the rate of increase of the exciting current is set to a certain time after the electric load input is detected or after the electric load input is detected. A voltage control device for an alternator for a vehicle, wherein the voltage is made higher than before the electric load is applied until the voltage again becomes equal to or higher than a set value. 2. The voltage control device for an on-vehicle AC generator according to claim 1, wherein a set value of a power generation voltage of the AC generator is increased when the increasing speed of the exciting current is increased. 3. The load application detection means, when the differential value of the voltage decrease amount of the vehicle battery is equal to or more than a predetermined value,
The method according to claim 1, wherein the application of the electric load is detected.
Alternatively, the voltage control device of the vehicle alternator according to the item 2. 4. The control operation is performed at least when the vehicle engine is idle.
The voltage control device for the vehicle alternator described.