JP2541224Y2 - Control device for vehicle alternator - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for a vehicle alternator.

[0002]

2. Description of the Related Art FIG. 4 is a circuit diagram showing a conventional apparatus. In the figure, reference numeral 1 denotes an AC generator driven by an engine (not shown) installed in a vehicle, and includes an armature coil 101 and a field coil. 102. Reference numeral 2 denotes a rectifier for performing full-wave rectification on the AC output of the AC generator 1, and has output terminals 201, 202, and 203.
have. 201 is a main rectification output terminal, 202 is an auxiliary rectification output terminal for passing an exciting current of the field coil 102, 203 is a ground terminal, 3 is a field coil 10 which detects a voltage generated by the generator.
2 is a voltage regulator for intermittently controlling the exciting current and controlling the generated voltage of the generator to a predetermined value, and is composed of the following components. 301 302 is a voltage dividing resistor that divides the voltage generated by the generator, 303 and 304 are voltage dividing resistors that divide the voltage of the constant voltage source (A) to form a reference voltage, and 305 is a generator that is divided by 301 and 302. The comparator compares the voltage with the reference voltage divided by 303 and 304, and detects the voltage generated by the generator.

Reference numeral 306 denotes a transistor which is turned on and off in accordance with the output of the comparator 305, reference numeral 307 denotes a base resistance of the transistor 306, reference numeral 308 denotes an output transistor.
, So that the field current of the field coil 102 is controlled. 309 is the base resistance of the output transistor 308, 310
A diode is connected in parallel with the field coil 102 and absorbs an intermittent surge generated in the field coil 102. 7 is a storage battery mounted on the vehicle and charged by the rectified output of the generator 1, 8 is a key switch, 9 is an electric load of the vehicle, 10
Is an electric load switch, 11 is a backflow prevention diode, and 12 is a resistance for initial excitation of the field coil 102.

Next, the operation will be described. When the key switch 8 is closed when the engine is started, a base current flows from the storage battery 7 to the output transistor 308 via the key switch 8, the backflow prevention diode 11, the initial excitation resistor 12, and the base resistor 309 of the output transistor 308. , The output transistor 308 conducts. The output transistor 308
Is conducted, a field current flows from the storage battery 7 to the field coil 102 via the key switch 8, the backflow prevention diode 11, the initial excitation resistor 12, the field coil 102, and the output transistor 308, and the generator 1 Power generation is possible.

Next, when the engine is started and the generator 1 is driven to rotate to start power generation, the voltage regulator 3 compares the voltage generated by the generator 1 with a reference voltage consisting of a voltage dividing resistor 301 302 and a voltage dividing resistor 303 304. When the voltage generated by the generator 1 is divided by the voltage dividing resistor 301 302, the voltage of the constant voltage source (A) exceeds a predetermined value set by the voltage dividing resistor 303 304.
The comparator 305 changes from the conduction state to the interruption state, and the comparator 305
The transistor 306 which is turned on and off in response to the output of the transistor 306 is turned on. Conversely, when the voltage generated by the generator 1 divided by the voltage dividing resistor 301 302 becomes equal to or less than a predetermined value set by the voltage dividing resistor 303 304, the comparator 305 changes from the cut-off state to the conductive state, and the transistor 306 changes from the conductive state. It is shut off. The output transistor 308 is turned on and off by the above-mentioned turning on and off of the transistor 306, and the field current flowing through the field coil 102 is intermittently controlled.
The generated voltage of the generator 1 is adjusted to a predetermined value.

[0006]

By the way, in such a conventional apparatus, when the electric load of the vehicle is light, the relatively large electric load 9 of the vehicle is turned on by the switch 10 and the generator 1 is turned on. When the output current of the generator 1 increases rapidly, the driving torque of the generator 1 increases, which causes a problem that the rotation speed of the engine that drives the generator 1 drops or the driver of the vehicle feels uncomfortable.

This invention has been made to solve the above-mentioned problems, and when the electric load of the vehicle is turned on, the output current of the generator is gradually changed, so that the driving torque of the generator is rapidly increased. Therefore, it is an object of the present invention to provide an AC generator control device which can prevent a drop in the engine speed and give a discomfort to a vehicle operator by suppressing the discharge of a storage battery as much as possible.

[0008]

A detection circuit for detecting an output voltage of an AC generator for a vehicle having a field coil and generating a signal voltage, and a smoothing circuit for smoothing the signal voltage and outputting a smoothed voltage. A triangular oscillator that generates a triangular waveform voltage at a constant period, a comparator that compares the triangular waveform voltage and the smoothed voltage from the smoothing circuit and outputs a pulse width modulated wave whose pulse width gradually changes, A semiconductor switching element for intermittently controlling a field current supplied to the field coil based on the width modulation wave, and a conductivity of the semiconductor switching element increasing by a predetermined amount when an output voltage of the AC generator becomes a predetermined value or less. And means for gradually ascending.

[0009]

The smoothing circuit in this invention delays the follow-up of the operation of the detection circuit, so that the semiconductor switching element does not perform the intermittent operation of the detection circuit even when the electric load of the vehicle is turned on. The intermittent operation of the comparator for comparing the circuit with the triangular waveform voltage is performed up to the operation level of the detection circuit. Further, when the electric load of the vehicle is turned on and the output voltage of the AC generator becomes equal to or lower than a predetermined value, control is performed so that the conductivity of the semiconductor switching element is increased by a predetermined value and then gradually increased.

[0010]

[Embodiment 1] An embodiment of the present invention will be described below with reference to FIG. FIG.
318, a backflow prevention diode for blocking current when the comparator 305 is cut off, 319, a level shift diode connected in series to the base terminal of the transistor 306,

Reference numeral 4 denotes a voltage generated by the generator 1 for dividing resistors 301 and 30.
2 and a predetermined voltage set by the voltage dividing resistors 303 and 304. The comparator 305 is a detection circuit that generates a high-low binary signal voltage.
Is configured by the following units.

Reference numeral 401 denotes a backflow prevention diode for blocking a current when the comparator 305 is cut off, reference numeral 402 denotes a resistor for defining a time constant for charging a capacitor 404 described later when the comparator 305 is cut off, and reference numeral 403 denotes the resistor 402. A diode for charging and holding a capacitor 404 to be described later through the capacitor 404; a capacitor 404 that is charged when the comparator 305 is turned off; and a resistor 405 that defines a time constant when the capacitor 404 is discharged when the comparator 305 is turned on. ,

Reference numeral 5 denotes a triangular wave generator for generating a triangular waveform voltage at a constant period in a predetermined voltage range, and 6 compares the smoothed voltage of the smoothing circuit 4 with the triangular waveform voltage of the triangular waveform generator 5. This is a comparison circuit for intermittently controlling the output transistor 308, and includes the following units. Reference numeral 601 denotes a comparator for comparing the smoothed voltage of the smoothing circuit 4 with the triangular waveform voltage of the triangular waveform generator 5; 602, a transistor which is a controller for controlling the output transistor 308 in accordance with the output of the comparator 601; Is the base resistance of the transistor 602.

Next, the operation will be described. When the voltage generated by the generator 1 is adjusted to a predetermined value with a constant electric load of the vehicle, a pulse which is an output of the comparator 601 which compares the smoothed voltage of the smoothing circuit 4 with the triangular waveform voltage of the triangular waveform generator 5. The width-modulated wave causes a field current necessary for the output current of the generator 1 to flow, and becomes a cut-off / conduction duty ratio. In response to the output of the comparator 601, the transistor 602 controls the output transistor 308 and the output transistor 308 The field current flowing through the field coil 102 is intermittently controlled to adjust the voltage generated by the generator 1 to a predetermined value.

Next, when the electric load 9 of the vehicle is turned on by the switch 10 (shown in FIG. 3A), the voltage generated by the generator 1 is divided by the voltage dividing resistor 301 302 to the constant voltage source (A).
Becomes lower than a predetermined value set by the voltage dividing resistors 303 and 304, and the comparator 305 changes from the cut-off state to the conductive state (FIG. 3B).
The transistor 306 is turned off from conduction, and the output transistor 308 conducts at a 100% duty ratio (conductivity) to try to supply a field current to the field coil 102, but the comparator 305 is conducting. Therefore, the voltage smoothed by the smoothing circuit 4 becomes a discharge voltage from the capacitor 404 to the resistor 405.

Here, if the ratio of the resistance values of the resistor 402 and the resistor 405 is set to 2: 1, the capacitor 404 can be obtained by this voltage dividing ratio.
Is charged, for example, before the electric load 9 is turned on, the output transistor 308 has a 50% duty ratio (conductivity).
If controlled by 306, capacitor 404 is 66.7
%, Which is equivalent to 50% in the duty ratio of the output transistor 308.
The control of 6 has priority.

On the other hand, when the electric load 9 is turned on, the transistor 306 is turned off, and the duty ratio of the output transistor 308 is controlled to be 100% equivalent.
With the duty ratio of the output transistor 308 charged to 6
The transistor 602 is controlled at a duty ratio of 6.7%, and the control of the transistor 602 is given priority.
% Duty ratio.

The discharge time constant of the capacitor 404 and the resistor 405 is large (shown in FIG. 3C). The output of the comparator 601 is based on a comparison between the discharge voltage of the triangular wave generator 5 and the discharge voltage of the smoothing circuit 4. The transistor 602 is turned on and off in accordance with the output of the comparator 601 by performing an intermittent operation of conducting and shutting off at a constant cycle until it reaches a predetermined value, and the output transistor 308 has a duty ratio as shown in FIG. 3f, the field current flowing through the field coil 102 is controlled to delay the generation of the output current of the generator 1 as shown in FIG. 3f.

When the output current of the generator 1 reaches a current corresponding to the electric load 9 of the vehicle conducted by the switch 10 and the voltage generated by the generator 1 reaches a predetermined value, the output of the comparator 601 is 1. Conduction of field current required for output current of 1,
The cut-off duty ratio becomes the
In response to the output of 601, the output is controlled and the output transistor 308 is controlled to control the field current flowing through the field coil 102 to adjust the voltage generated by the generator 1 to a predetermined value.

Even if the electric load 9 of the vehicle is turned on by the switch 10, the output transistor 308 is controlled by comparing the discharge voltage of the smoothing circuit 4 with the triangular wave voltage of the triangular wave generator 5. This makes it possible to suppress the output current of the generator 1 for a certain period of time as shown in FIG. 2 and prevent a sudden increase in the driving torque.

Further, when the electric load 9 of the vehicle is turned on by the switch 10, the conductivity of the output transistor 308 rises by a predetermined amount and thereafter gradually increases, so that the conductivity of the output transistor 308 is increased. Is gradually reduced, and discharge of the storage battery 7 can be suppressed as much as possible.

Embodiment 2 FIG. In the above embodiment, the comparator 305 is used to detect the voltage generated by the generator 1. However, a detection circuit including a transistor and a zener diode may be used.

[0023]

As described above, according to the present invention, a detection circuit for detecting an output voltage of an AC generator for a vehicle having a field coil and generating a signal voltage, and smoothing the signal voltage by smoothing the signal voltage. A smoothing circuit that outputs a voltage, a triangular wave oscillator that generates a triangular wave voltage at a constant period, and a pulse width modulated wave whose pulse width gradually changes by comparing the triangular wave voltage and the smoothed voltage from the smoothing circuit A semiconductor switching element for intermittently controlling a field current supplied to the field coil based on the pulse width modulation wave; and a pulse width modulation when an output voltage of the AC generator falls below a predetermined value. Means for increasing the conductivity of the semiconductor switching element by a predetermined amount by means of a wave and then gradually increasing the output of the semiconductor switching element. Can suppression, drop in the rotational speed of the engine of a vehicle, also it is possible to prevent discomfort to the vehicle operator, moreover, has the advantage of being able to suppress the discharge of the battery as much as possible.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment according to the present invention.

FIG. 2 is a characteristic diagram showing a comparison between the embodiment of the present invention shown in FIG. 1 and a conventional example.

FIG. 3 is a characteristic diagram of each part according to an embodiment of the present invention.

FIG. 4 is an electric circuit diagram of a conventional device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC generator 2 Rectifier 3 Voltage regulator 4 Smoothing circuit 5 Triangular wave generator 6 Comparison circuit 7 Storage battery 9 Electric load 101 Armature coil 102 Field coil 308 Output transistor 402,405 Resistance 404 Capacitor 601 Comparator 602 Transistor

Claims (1)

(57) [Scope of request for utility model registration] 1. A detection circuit for detecting an output voltage of an automotive alternator having a field coil to generate a signal voltage, a smoothing circuit for smoothing the signal voltage and outputting a smoothed voltage, and a triangular wave having a constant period. A triangular wave oscillator that generates a voltage, a comparator that compares the triangular wave voltage with the smoothed voltage from the smoothing circuit and outputs a pulse width modulated wave whose pulse width gradually changes, and the field based on the pulse width modulated wave A semiconductor switching element for intermittently controlling the field current supplied to the coil, and when the output voltage of the AC generator becomes a predetermined value or less, the pulse width modulation wave increases the conductivity of the semiconductor switching element by a predetermined amount. Then, a control device for a vehicle alternator having means for gradually ascending.