JPH08233871A - Apparatus for establishing/detecting output voltage of a.c. generator - Google Patents

Abstract

PURPOSE: To provide an output voltage-establishing/detecting apparatus of an A.C. generator which does not generate great hysteresis in the detection operation and does not accompany a malfunction by noises. CONSTITUTION: An inter collect or/emitter circuit of a transistor Tr1 is connected via a resistor R1 and a light-emitting diode LED between output terminals of a rectifier circuit 2 for rectifying an output voltage of an A.C. generator 1. When the output voltage of the A.C. generator 1 reaches a set value, a base current is fed to the transistor Tr1 to turn the transistor Tr1 conductive, thereby turning ON the light-emitting diode LED. The light emitted from the light- emitting diode is detected by a photo transistor PTr. When the photo transistor PTr becomes conductive, a transistor Tr2 is connected. A detecting signal is output through the transistor Tr2 .

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output voltage establishment detecting device for an alternator that generates a detection signal when the output voltage of the alternator is established and exceeds a set value.

[0002]

2. Description of the Related Art A power supply facility using an AC generator driven by an internal combustion engine or the like, for example, an emergency power generation facility used as a substitute power source when a commercial power supply fails,
When the generator starts rotating and the output voltage is established and becomes equal to or higher than the set value, a detection signal is generated to start power supply to the load, or an abnormality occurs during operation of the generator. In order to detect when the output voltage of the generator falls below the set value, an output voltage establishment detection device that generates a detection signal when the output voltage falls below the set value for determining the output voltage establishment is provided. Is desirable.

FIG. 5 shows a schematic circuit of an output voltage establishment detecting device for an AC generator which has been conventionally used. In FIG. 5, 1 is an AC generator and 6 is an output terminal 1a of the AC generator 1. , 1b, and an electromagnetic relay for detecting an output voltage establishment, which has an exciting coil 61 connected between the first and second terminals, and a normally open contact 62 which is closed when the exciting coil is excited.

The exciting coil 61 is excited by the output voltage of the AC generator 1, the output voltage of the generator rises, and the output voltage establishment determination set value determined by the minimum pickup voltage of the electromagnetic relay 6, for example, the AC generator 1. 80% of rated voltage
When the voltage becomes equal to or higher than, the normally open contact 62 of the electromagnetic relay closes. The establishment of the output voltage of the AC generator 1 can be detected by closing the normally open contact 62. The closing of the normally open contact 62 is used as a detection signal, and the output terminals 6a, 6 of the electromagnetic relay 6 are
It is possible to operate a display circuit (not shown) connected between b and a control circuit for controlling the energization of the load from the generator. When the output voltage of the AC generator 1 decreases to a maximum dropout voltage of the electromagnetic relay 6, for example, 30% or less of the rated voltage of the AC generator 1, the normally open contact 62 of the electromagnetic relay opens.

FIG. 6 shows an example of the output voltage of the AC generator 1 and the ON / OFF state of the contact 62 of the electromagnetic relay 6, in which the output voltage of the AC generator 1 rises. The voltage at which the contact 62 is turned on during the process (voltage of 80% of the rated output voltage of the alternator in this example) is turned off during the process of decreasing the output voltage (AC generated in this example). 30% of the rated output voltage of the machine)
It is considerably lower as seen in the general characteristics of electromagnetic relays.

[0006]

The above-mentioned conventional output voltage establishment detecting device for an AC generator uses the electromagnetic relay to detect the establishment of the output voltage, and therefore has the following problems.

(1) Since the output voltage setting value for determining whether or not the output voltage of the generator has been established (output voltage establishment determination setting value) depends on the characteristics of the electromagnetic relay used, The set value cannot be freely selected.

(2) Generally, in an electromagnetic relay, there is a large difference between the exciting voltage when the contact is in the ON state (minimum pickup voltage) and the exciting voltage when the contact is in the OFF state (maximum dropout voltage). Therefore, it is inevitable that large hysteresis occurs in the detection operation in the process of increasing the output voltage of the generator and the detection operation in the process of decreasing the output voltage.
Therefore, if the conventional output voltage establishment detection device is also used to detect the state where the output voltage of the alternator is insufficient, the set value for determining the output voltage shortage (output voltage shortage determination set value) is The output voltage is significantly lower than the set value for determining the establishment of the output voltage, and the shortage of the output voltage cannot be accurately detected.

(3) Since the detection operation has a large hysteresis, even if the output voltage of the alternator is lower than the set value for the output voltage establishment determination, the output voltage establishment determination setting is made for a short time due to noise or the like. When a voltage higher than the value is generated, the contacts of the electromagnetic relay may be closed, and the closed state may be maintained, which may cause erroneous detection due to noise.

An object of the present invention is to provide an output voltage establishment detecting device for an AC generator, which can freely select a set value for determining the establishment of the output voltage of the AC generator.

Another object of the present invention is to provide an output voltage establishment detecting device for an AC generator in which there is no possibility that a malfunctioning state will continue due to noise or the like.

Still another object of the present invention is to ensure that a large hysteresis does not occur in the operation of establishing and lowering the output voltage so that not only the output voltage of the alternator but also the shortage of the output voltage can be properly determined. Another object of the present invention is to provide an output voltage establishment detection device for an alternator capable of detecting the output voltage.

[0013]

SUMMARY OF THE INVENTION The present invention is an output voltage establishment detecting device for detecting that the output voltage of an alternator is established and is equal to or higher than a set value, and rectifies the output voltage of the alternator. Rectifying circuit, a collector-emitter circuit connected between the output terminals of the rectifying circuit through the current limiting element and the light-emitting element, and output when the generator output voltage reaches the set value. A transistor drive circuit that supplies a base current to the voltage detection transistor to make the transistor conductive, and a light receiving element that detects light generated by the light emitting element when the output voltage detection transistor is conductive and becomes conductive. A detection signal output transistor that is rendered conductive by receiving a base current through the light receiving element, and an output voltage is established when the detection signal output transistor is rendered conductive. Composed of a detection signal output circuit for outputting a detection signal indicating that the.

The detection signal output circuit discharges the electric charge of the capacitor charged through the light receiving element when the light receiving element is conductive and the base-emitter circuit of the detection signal outputting transistor with a constant time constant. And a discharge circuit.

[0015]

According to the present invention, when the output voltage of the AC generator is established and becomes equal to or higher than the set value, a base current flows and the transistor is turned on to detect the establishment of the output voltage. With such a configuration, the output voltage establishment determination set value can be freely set by appropriately selecting the circuit conditions of the transistor drive circuit.

Further, since there is almost no hysteresis in the on / off operation of the transistor, if the above configuration is adopted,
Unlike the conventional device using the electromagnetic relay, a large hysteresis does not occur in the detection operation for detecting the establishment and shortage of the output voltage. Therefore, not only the establishment of the output voltage but also the shortage of the output voltage can be accurately detected.

Furthermore, since there is no large hysteresis in the detection operation, when the output voltage of the generator is lower than the set value,
Even if a detection signal indicating the establishment of the output voltage is generated due to noise, if the noise disappears, the detection signal immediately disappears. Therefore, it is possible to prevent erroneous detection due to noise.

Further, as described above, when the output voltage detection circuit and the detection signal output circuit are coupled by the light emitting element and the light receiving element which detects the light generated by the light emitting element and becomes conductive, the output is obtained. Since electrical interference can be prevented from occurring between the voltage detection circuit and the detection signal output circuit, malfunction due to noise can be prevented.

Further, as described above, a capacitor is charged through the light receiving element when the light receiving element becomes conductive, and a discharge for discharging the electric charge of the capacitor with a constant time constant through the circuit between the base and emitter of the detection signal outputting transistor. If the detection signal output circuit is composed of a circuit, even if there is a ripple in the rectified output voltage of the AC generator, the detection signal output transistor must be held in the conductive state if the output voltage of the AC generator is greater than the set value. Therefore, the risk of malfunction due to ripple can be eliminated.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. In FIG. 1, reference numeral 1 is an AC generator driven by an internal combustion engine or the like (not shown). The AC generator 1 is used as an alternative power source in an emergency such as a power failure of a commercial power source, and a load is connected between the output terminals 1a and 1b of the AC generator 1 via a power feeding circuit (not shown). ing.

A rectifier circuit 2 is also connected between the output terminals 1a and 1b of the AC generator 1. This rectifier circuit
Diode D1 whose anode is connected to one output terminal 1a, and the other output terminal 1b of the generator and diode D1
It has a diode D2 whose anode is connected to the output terminal 1b side between the cathode of the diode D1 and the output of the AC generator 1 is half-wave rectified by the diode D1. The diode D2 is provided to clamp the reverse voltage of the next-stage circuit to about 0.5 V during the reverse breakdown voltage recovery time of the diode D1.

As the rectifier circuit 2, a single-phase full-wave rectifier circuit formed by connecting four diodes in a bridge may be used.

Between the output terminals 2a and 2b of the rectifier circuit 2,
The collector-emitter circuit of the output voltage detecting transistor Tr1 is connected through the current limiting element and the light emitting element. In the illustrated example, the output voltage detection transistor Tr1 is a PNP transistor, the emitter of which is connected to the positive side output terminal 2a of the rectifier circuit, and the collector is a resistor R1 as a current limiting element and a light emitting element. Rectifier circuit 2 through the light emitting diode LED
Is connected to the negative output terminal 2b.

Between the output terminals 2a and 2b of the rectifier circuit 2,
A voltage dividing circuit consisting of a series circuit of resistors R2 and R3 is connected, and a Zener diode ZD with its anode facing the voltage dividing point is connected between the voltage dividing point of this voltage dividing circuit and the base of the transistor Tr1. There is.

In this example, the resistors R2 and R3 and the Zener diode ZD form a transistor drive circuit that supplies a base current to the output voltage detecting transistor Tr1 to bring the transistor Tr1 into a conductive state.

In this embodiment, when the output voltage of the AC generator 1 reaches the set value Vs (effective value) for determining the output voltage, the peak value of the voltage across the resistor R2 is √2Vs R2 / (R
2 + R3) becomes almost equal to the Zener voltage of the Zener diode ZD (more precisely, equal to the sum of the Zener voltage of the Zener diode ZD and the voltage drop between the emitter and the base of the transistor Tr1), and the output voltage through the Zener diode ZD. The resistance values of the resistors R2 and 3 are set so that the base current flows through the detection transistor Tr1.

The light emitting diode LED constitutes a photocoupler 3 together with a phototransistor PTr as a light receiving element. When the output voltage detecting transistor Tr1 becomes conductive and the light emitting diode LED emits light, the phototransistor PTr becomes conductive. A possible state (a state in which the collector and the emitter become conductive when a predetermined voltage is applied between them).

The emitter of the phototransistor PTr is grounded, and the collector is connected to the base of the detection signal output transistor Tr2 which is a PNP transistor via a resistor R4. The emitter of the transistor Tr2 is connected to a DC voltage input terminal 4 to which a DC voltage Vcc is applied from a DC power source (not shown) such as a battery, and the collector of the transistor Tr2 is grounded via a resistor R5. Detection signal output terminals 5a and 5b from both ends of the resistor R5
Has been derived.

A capacitor C is connected between the emitter of the detection signal output transistor Tr2 and the collector of the phototransistor PTr, and a phototransistor is formed by a circuit of DC voltage input terminal 4 → capacitor C → phototransistor PTr → ground. When PTr becomes conductive, the phototransistor PTr is driven by the DC power supply voltage Vcc.
A charging circuit for charging the capacitor C through is configured. Further, the circuit of capacitor C → emitter base of transistor Tr2 → resistor R4 → capacitor C constitutes a discharge circuit for discharging the charge of capacitor C with a constant time constant when phototransistor PTr becomes non-conductive. . Here, the charging voltage of the capacitor C is Vc,
When the base-emitter voltage of the detection signal output transistor Tr2 is VBE, the duration T of the discharge current flowing through the discharge circuit is T = R4.C.ln (Vc / VBE) [ln
Is the natural logarithm]. In this embodiment, by appropriately setting the value of the time constant R4 · C of the discharge circuit, the cycle (1 / frequency) of the output voltage of the alternator 1 when the phototransistor PTr is in the cutoff state. For a longer period of time, the above discharge is performed so that a discharge current (base current) larger than a value necessary for holding the transistor Tr2 in a conductive state can flow from the capacitor C between the emitter and the base of the transistor Tr2. Duration T
Is set to be sufficiently longer than the cycle of the output voltage of the AC generator 1.

In this embodiment, the phototransistor PTr is used.
, Detection signal output transistor Tr2, and capacitor C
And the resistors R4 and R5 form a detection signal output circuit.

In the embodiment shown in FIG. 1, when the output voltage of the AC generator 1 rises and its effective value becomes equal to or higher than the set value Vs for determining the output voltage establishment, the Zener diode ZD becomes conductive and the rectifier circuit 2 is turned on. Due to the rectified output voltage of the generator generated between the output terminals 2a and 2b, the terminal 2a → transistor T
r1 emitter-base circuit → Zener diode ZD →
A base current flows through the output voltage detecting transistor Tr1 through the path of the resistor R3 → terminal 2b, and the transistor Tr1 becomes conductive. When the transistor Tr1 becomes conductive, a current flows through the light emitting diode LED of the photocoupler 3 through the transistor and the light emitting diode emits light. Photo coupler 3
Phototransistor PTr is a light emitting diode LED
While light is being emitted, this light is detected and it becomes conductive. When the phototransistor PTr becomes conductive, the DC voltage input terminal 4 → emitter-base circuit of the transistor Tr2 → resistor R4 → phototransistor PTr → the base current I1 of the detection signal output transistor Tr2 in the direction of the broken arrow shown in the drawing along the ground path. Flows and the transistor Tr2 becomes conductive. At the same time, at the same time, the charging current I2 in the direction of the broken arrow in the figure flows through the capacitor C, and the capacitor is charged to the polarity shown in the figure.

Even if the output voltage of the AC generator 1 is equal to or higher than the set value for determining the output voltage establishment, if the output voltage of the rectifier circuit 2 contains a ripple, the ripple voltage will be affected. The phototransistor PTr repeats the conducting state and the non-conducting state, but when the phototransistor becomes the non-conducting state, the electric charge of the capacitor C is charged to the capacitor C → the emitter-base circuit of the transistor Tr2 →
A discharge current I3 flows in the direction of the broken line arrow in the figure by discharging from the path of the resistor R4 to the capacitor C. Therefore, a predetermined base current is supplied to the detection signal output transistor Tr2 by this discharge current I3, and the transistor Tr2 is held in the conductive state. As described above, the discharge duration T of the capacitor C is set to be sufficiently longer than the cycle of the output voltage of the AC generator 1, and the output voltage of the AC generator becomes equal to or higher than the output voltage establishment determination set value. In this state, the predetermined base current continues to be supplied to the transistor Tr2 even when the phototransistor PTr is in the cutoff state, so that the detection signal output transistor Tr2 is held in the conductive state.

When the detection signal output transistor Tr2 is turned on, the transistor T2 is turned on from the DC voltage input terminal 4.
A current flows through the resistor R5 through r2, and a voltage Vcc 'approximately equal to the power source voltage Vcc appears across the resistor R5. Therefore, the detection signal voltage output from between the detection signal output terminals 5a and 5b rises to the voltage Vcc 'when the output voltage of the AC generator 1 is established.

When the output voltage of the AC generator 1 drops and becomes lower than the set value Vs for determining the output voltage establishment, the Zener diode ZD maintains the non-conducting state, so that the output voltage detecting transistor Tr1 is non-conducting state. , And the detection signal voltage obtained between the detection signal output terminals 5a and 5b becomes zero.

Therefore, according to this embodiment, the detection signal voltage obtained between the output terminals 5a and 5b changes from zero level to V
By confirming that it has risen to cc '(high level), it is possible to detect that the output voltage of the generator has been established, and confirm that the detection signal voltage has dropped from high level to zero level. Thus, it is possible to detect that the output voltage of the generator is insufficient (including the state where the output voltage is zero).

FIG. 2 shows an AC generator 1 in the above embodiment.
Detection signal output terminals 5a, 5 when the output voltage of the
It shows the detection signal voltage obtained between b. The generator output voltage when the output voltage is established and the detection signal voltage rises to Vcc 'in the process in which the output voltage of the AC generator rises (process in the direction of the solid line arrow in the figure), and the output voltage of the AC generator falls. It can be seen that there is almost no difference between the detection signal voltage and the generator output voltage when the detection signal voltage disappears in the process (the direction indicated by the broken line arrow in the figure), and there is almost no hysteresis in the detection operation.

Therefore, when the output voltage of the generator is lower than the set value for determining the output voltage establishment, the output voltage detecting transistor Tr1 becomes conductive due to noise and a detection signal indicating the establishment of the voltage is generated. Even if the noise disappears, the transistor Tr1 immediately enters the cutoff state and disappears the detection signal indicating the establishment of the voltage. Therefore, the generation of the detection signal due to the noise and the generation of the detection signal due to the establishment of the output voltage are clearly defined. It is possible to make a distinction, and it is possible to eliminate the possibility of false detection due to noise.

Further, as described above, when the output voltage setting value (output voltage establishment determination setting value) for determining whether or not the output voltage of the AC generator 1 is established is Vs (effective value), When the output voltage of the alternator reaches the set value Vs and the value of the divided voltage output of the voltage dividing circuit √2Vs R2 / (R2 + R3) becomes almost equal to the Zener voltage (Vz) of the Zener diode ZD, Since the detection signal voltage obtained between the detection signal output terminals 5a and 5b rises to the voltage value Vcc 'which is almost equal to the power supply voltage Vcc and the establishment of the voltage is detected, the output voltage establishment determination set value Vs is Vs = Vz. (R2 + R3
) / √2R2. Therefore, the output voltage establishment determination set value Vs can be freely selected by selecting the resistance values of the resistors R2 and R3 of the voltage dividing circuit.

Further, in this embodiment, the output voltage detection circuit side of the AC generator (left half of the circuit of FIG. 1) and the detection signal output circuit side (right half of the circuit of FIG. 1) are connected by the photocoupler 3. Since they are coupled (via light), it is possible to prevent electrical interference between the output voltage detection circuit and the detection signal output circuit, and the detection signal output circuit malfunctions due to electrical noise, resulting in false detection. Can be prevented.

In the above embodiment, PNP transistors are used as the output voltage detecting transistor Tr1 and the detection signal outputting transistor Tr2, respectively. However, even if NPN transistors are used as these transistors, the output voltage establishment detecting device of the present invention can be used. Can be configured.

FIG. 3 shows an embodiment in which NPN transistors are used as the output voltage detecting transistor Tr1 and the detection signal outputting transistor Tr2. In this embodiment, the collector of the output voltage detecting transistor Tr1 is a photocoupler 3. Through the light emitting diode LED and the resistor R1 as a current limiting element
The emitter is connected to the negative output terminal 2b of the rectifier circuit 2. Output terminals 2a, 2 of the rectifier circuit 2
Between b, a voltage divider circuit composed of a series circuit of resistors R2 and R3 connects the resistor R2 to the negative output terminal 2b of the rectifier circuit 2.
Connected in a state of being positioned on the side, and between the voltage dividing point of this voltage dividing circuit and the base of the output voltage detecting transistor Tr1,
The Zener diode ZD is connected with its anode facing the base side of the transistor Tr1.

Further, in this example, the phototransistor PT
The collector of r is connected to the DC voltage input terminal 4, and the emitter of the phototransistor is connected to the base of the detection signal output transistor Tr2 via the resistor R4. The detection signal output transistor Tr2 has its emitter grounded and its collector connected via a resistor R5 to a DC voltage input terminal 4
It is connected to the. The detection signal output terminals 5a and 5b are derived from the collector and the emitter of the detection signal output transistor Tr2, respectively. The capacitor C is connected between the emitter of the detection signal output transistor Tr2 and the emitter of the phototransistor PTr. The other points are similar to those of the circuit shown in FIG.

In this embodiment, the phototransistor PT
When r is turned on, the DC current input terminal 4-> phototransistor PTr-> resistor R4-> base-emitter circuit of the transistor Tr2-> the base current I1 of the detection signal output transistor Tr2 flows in the path of ground, and the DC voltage input terminal. → Phototransistor PTr → Capacitor C → The charging current I2 of the capacitor C flows through the path of grounding. When the phototransistor PTr becomes non-conducting, the electric charge of the capacitor C is discharged along the path of the capacitor C → the resistor R4 → the base-emitter circuit of the transistor Tr2 → the capacitor C to the detection signal output transistor Tr2. A base current I3 flows.

In the embodiment shown in FIG. 3, when the output voltage of the AC generator 1 is lower than the output voltage establishment determination set value Vs, the detection signal output transistor Tr2 is in the cutoff state, and the detection signal output A value Vcc 'at which the detection signal voltage obtained between the terminals 5a and 5b is substantially equal to the DC power supply voltage Vcc
(High level). When the output voltage of the AC generator 1 becomes equal to or higher than the output voltage establishment determination set value Vs, the detection signal output transistor Tr2 becomes conductive and the voltage between the detection signal output terminals 5a and 5b becomes substantially zero level.

Therefore, in this embodiment, the state in which the detection signal voltage is high is the state in which the output voltage of the generator is insufficient, and the state in which the detection signal voltage is almost zero is the power generation. The output voltage of the machine has been established. FIG. 4 shows how the detection signal voltage changes between the detection signal output terminals 5a and 5b when the output voltage of the AC generator 1 changes in this embodiment.

In the embodiments of FIGS. 1 and 3, the detection signal voltage obtained between the detection signal output terminals 5a and 5b can be used to control a control circuit or the like for controlling the energization of the load. For example, switch means (for example, an electromagnetic relay) for controlling energization is provided between the alternator and the load, and when the detection signal voltage detects that the output voltage of the generator is established, the switch means is provided. Is turned on to start energizing the load from the alternator, and when a shortage of output voltage of the generator is detected, the switch means is turned off to stop energizing the load from the alternator. In addition, the energization of the load can be controlled by the detection signal voltage.

Further, it is possible to detect the failure of the generator by determining the state in which the shortage of the output voltage is detected even when the rotation speed of the AC generator 1 reaches a predetermined value, as the failure state.

In the embodiment of FIG. 3, the detection signal voltage becomes high level when the output voltage of the generator is insufficient,
Although the detection signal voltage is set to the zero level when the output voltage of the generator is established, in the embodiment shown in FIG.
By adding a signal inverting circuit between the output terminals 5a and 5b, if necessary, to obtain a detection signal voltage (a detection signal voltage which becomes a high level when the output voltage is established) similar to that of the embodiment of FIG. You can

In the above embodiments, the present invention is applied to a single-phase AC generator, but the present invention can also be applied to a multi-phase AC generator having three or more phases. To apply the present invention to a polyphase AC generator, the rectifier circuit 2 is changed to a current circuit for polyphase AC, or the rectifier circuit of each of the above embodiments is connected to only one phase of the polyphase AC generator. You can do it.

[0050]

As described above, according to the present invention, when the output voltage of the AC generator is equal to or higher than the set value, the transistor drive circuit supplies the base current to provide the output voltage detecting transistor which becomes conductive. Therefore, the detection signal is generated when the transistor is in the conductive state, and the detection signal is prevented from being generated when the output voltage of the AC generator is less than the set value, so that the output voltage of the AC generator rises. In order to prevent a large difference between the output voltage value of the generator when the detection signal is generated and the output voltage value of the generator when the detection signal disappears in the process of decreasing the output voltage. be able to. Therefore, when the output voltage of the AC generator becomes equal to or higher than the set value for a short time due to noise or the like, it is possible to eliminate the possibility that the detection signal will be continuously generated, and eliminate the risk of erroneous detection. it can.

Since no hysteresis occurs in the detection operation, it is possible to accurately detect the shortage of the output of the generator.
It can be used not only for detecting the establishment of the output voltage of the alternator, but also for detecting that the output voltage has become insufficient due to a failure or the like.

Further, in the present invention, by selecting the circuit constant of the transistor drive circuit for supplying the base current to the output voltage detecting transistor, the set value for determining whether or not the output voltage of the alternator is established is freely set. There is an advantage that can be selected.

Further, according to the present invention, since the output voltage detection circuit and the detection signal output circuit are coupled via the light emitting element and the light receiving element, electrical interference between the output voltage detection circuit and the detection signal output circuit. Can be prevented, and the detection signal output circuit can be prevented from malfunctioning due to electrical noise, resulting in erroneous detection.

According to the second aspect of the present invention, the capacitor charged through the light receiving element when the light receiving element conducts, and the electric charge of the capacitor is kept constant through the base-emitter circuit of the detection signal outputting transistor. Since the detection signal output circuit is composed of a discharge circuit that discharges with a time constant, even if there is a ripple in the rectified output voltage of the AC generator, if the output voltage of the AC generator is above the set value, the detection signal output transistor Can be maintained in a conductive state, and the risk of malfunction due to ripple can be eliminated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing the relationship between the output voltage of the AC generator and the detection signal voltage in the embodiment of FIG.

FIG. 3 is a circuit diagram showing another embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the output voltage of the AC generator and the detection signal voltage in the embodiment of FIG.

FIG. 5 is a circuit diagram showing a conventional example.

FIG. 6 is a diagram showing the relationship between the output voltage of the AC generator and the ON / OFF operation of the relay contacts in the conventional example of FIG.

[Explanation of symbols]

 1 AC generator 2 Rectifier circuit 2a, 2b Output terminal of rectifier circuit 3 Photocoupler 4 DC voltage input terminal 5a, 5b Detection signal output terminal ZD Zener diode LED Light emitting diode (light emitting element) PTr Phototransistor Tr1 Output voltage detection transistor Tr2 Detection signal output transistor C capacitor R1 resistance (current limiting element) R2 to R5 resistance

Claims (2)

[Claims] 1. An output voltage establishment detection device for detecting that the output voltage of an alternator has been established and has exceeded a set value, the rectifying circuit rectifying the output voltage of the alternator, and a collector emitter. And an output voltage detection transistor connected between the output terminals of the rectification circuit through a current limiting element and a light emitting element, and the output voltage detection transistor when the output voltage of the generator reaches a set value. A transistor drive circuit that supplies a base current to a transistor to bring the transistor into a conductive state, and a light receiving element that detects and conducts light generated by the light emitting element when the output voltage detection transistor is conductive,
A detection signal output transistor provided so that a base current is applied through the light receiving element to be in a conductive state, and detecting that the output voltage is established when the detection signal output transistor is conductive An output voltage establishment detection device for an alternator, comprising: a detection signal output circuit that outputs a signal. 2. The detection signal output circuit includes a capacitor charged through the light receiving element when the light receiving element conducts, and a constant charge of the capacitor through a base-emitter circuit of the detection signal outputting transistor. The output voltage establishment detecting device for an alternator according to claim 1, further comprising a discharging circuit for discharging at a constant number.