JPH02307400A - Automatic voltage regulator - Google Patents

Abstract

PURPOSE:To enable continuing operation until termination of an overload state at the time of detecting the increase of a field current due to overload by level- shifting a detection signal like the case when the output voltage of a generator rises. CONSTITUTION:In a field-current suppression circuit 12, a voltage generated in a current-detecting resistor R24 is amplified by an operational amplifier OP-AMP2 as a field current If flows through a field winding F-CL when a transistor for switching control of said field current If is ON, and a transistor Q6 is turned ON when the amplified output of said amplifier exceeds a specified value at the time of overload so that a resistor R30 is connected in parallel with a capacitor C4 in an integration circuit 11 to lower the reference voltage Vis of an amplifier OP-AMP1 forcedly. Therefore, the increase of said field current If is suppressed at the time of overload.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an automatic voltage regulator for an alternator driven by an engine or the like.

White in an alternator that rectifies the output of the active excitation winding and supplies field current to the field winding! l! The lJ voltage regulator detects a voltage signal proportional to the output voltage of the generator using a detection winding, rectifies the detected voltage signal, and then smooths it to some extent to intentionally create a pulsating detection signal. The detection signal is compared with a reference signal set to a constant value using a Zener diode or the like, and based on the comparison result, the field current is adjusted so that the output voltage of the generator is constant. It is common to perform switching control for energizing and shutting off (see Japanese Patent Laid-Open No. 113798/1983).

However, in this type of generator, the field current of the generator is controlled to increase as the load increases, so when a load with a large starting current, such as an electric motor, is connected, the field current increases. This tends to temporarily increase the heat generation temperature of the field winding beyond a specified value, or to place an excessive burden on a drive source such as an engine.

On the other hand, conventionally, when it is detected that the output voltage of the generator has decreased due to overload operation or temperature conditions at startup, the detection signal is compared with the reference signal during automatic voltage adjustment. Forcibly lower the level
It has also been attempted to take control measures to suppress the increase in field current (Japanese Patent Laid-Open No. 59-113798).
(see publication).

However, in this type of system, the state in which the output voltage of the generator is actually decreasing is detected, and then control is executed to suppress the increase in field current. If the increase in field current cannot be dealt with promptly, the operation is continued until the overload condition is resolved while maintaining the field current within a predetermined value and ensuring a good field current flow rate. It is difficult to control the process so that it continues to occur.

■-Target 1 The present invention was made in consideration of the above points, and the detection is obtained by detecting the output voltage of an alternator with a detection winding, rectifying the detected voltage signal, and smoothing it. When comparing the signal with a reference signal and controlling switching of the field current so that the output voltage of the generator is constant based on the comparison result, a predetermined regulation is applied to increase the field current in the event of an overload, etc. It is possible to quickly reduce the load to within the specified value, maintain that state, and continue operation until the overload condition is resolved. ! !
l] A voltage regulating device is provided.

-M Dai.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in Fig. 1, the AC generator is a three-phase case, and is wound around a stator core, and has three-phase output windings MU-CL, MV-CL, and MW-CL. , an excitation winding EX-CL wound around the same stator core, and a field winding F-CL wound around one rotor.

In addition, the output of the excitation winding EX-CL is the full-wave rectifier circuit RE.
It is configured to be rectified by CI and supplied to the field winding F-CL as a field current If.

The automatic voltage adjustment position is the output winding MU-CL, MV of each phase.
-CL, MW-CLL: Detection windings DU-CL, DV-CL forming a part of each output winding, respectively, to detect a voltage signal "ur ey + e↓" proportional to the output voltage at.

a generator output detection circuit l detected by DW-CL;
The detection voltages e'u and r ey + e- of the detection windings DU-CL, DV-CL, and DW-CL are connected to the diode D.
1, D2. A detection signal forming circuit that rectifies each signal by D3 and smooths the superimposed signal to a state with almost no pulsation in a smoothing circuit 2, and then takes out a detection signal DS via a variable resistor VR for adjusting the set voltage. 3, an integrating circuit 11 for integrating the detection signal DS, and a detection winding DU.
- A reference signal forming circuit 4 that forms a triangular wave-like reference signal SS according to each detection voltage of CL, DV-CL, and DW-CL, and a voltage ratio v of the reference signal SS and detection signal DS.
In MPiCMPI, the comparator C
A switching control circuit 5 controls turning on and off of the field current If by turning on and off a switching circuit including a transistor Q2 in accordance with the output signal of the MPI, and a switching control circuit 5 which controls the switching of the field current If by switching it on and off in accordance with the output signal of the MPI. The field current suppression circuit 12 detects the increase and shifts the level of the detection signal DS to suppress the increase in the field ffl flow If.

The reference signal forming circuit 4 includes a detection winding DU-CL.

DV-CL, DW-CL (7) Transistor Q3 as a switching element provided to be turned on in response to each detection voltage signal. A switching circuit 6 consisting of a transistor Q4.05 and its transistor Q3. Q4. A pulse string signal forming circuit that compares a voltage value Vd obtained by superimposing each output voltage Va, Vb, and Vc of Q5 with a preset voltage value Vs using a voltage comparator CMP2, and forms a pulse string signal PS based on the comparison result. 7 and its pulse train signal PS
Accordingly, the triangular wave signal forming circuit 8 forms a triangular reference signal SS in accordance with charging and discharging of the capacitor C2.

Note that (- transistor Q3 in the switching circuit 6
．． Q4. Each output voltage Va, Vb when Q5 is off,
Circuit constants are set so that the magnitudes of Vc are equal to each other.

Further, the set voltage value Vs in the voltage comparator CMP2 is 2
The maximum value of the superimposed voltage value Vd, that is, the transistors Q3 to Q
The superimposed voltage value Vdl becomes lower than the superimposed voltage value Vdl when two of the transistors 03 to 5 are turned off at the same time, and the superimposed voltage value Vdl is lower than the superimposed voltage value Vdl when only one of the transistors 03 to 5 is turned off. It is set to be higher than the voltage value Vd2 (see FIG. 2).

Here, R5= R6= R7= Rx, R8=
When R9=RIO=Ry, Vd1=VccXRy/ (((Rx+Ry)/2>
+Ry]Vd2=VccXRy/ ((Rx+Ry)+
Ry).

Also, 1-transistor Q3. Q4. Each emitter of Q5
Diodes D4, DS, and D6 are provided between the bases, and diodes D4, DS, and D6 are provided between each transistor Q3, Q4, and Q4. This prevents charge from accumulating on the base side when Q5 is off.

In the figure, 9 is a stabilized power supply circuit, a detection winding, a wire DU-C
L, DV-CL, DW-CL (7) Each detected ffi pressure is connected to a diode Di, D2. They are each rectified by D3, and the voltage Vcc is supplied based on the superimposed voltage.

A smoothing capacitor C3 is provided on the output side of the aftereffect rectifier circuit RECI that flows the output voltage of the excitation winding EX-CL, and a flywheel diode is connected in series with the field winding F-CL. D7 is provided.

In the figure, 10 is a three-phase AC 9. This is the output terminal section of an electrical machine.

FIG. 2 shows the tie 11char 1- of each part signal in the i&semi-double signal forming circuit 4.

According to the present invention, the field current If is applied in the switching control circuit 5 while comparing the DC detection signal DS and the triangular wave-like reference signal SS.

When performing the switching control of the cut-off, there is no need for a separate means for synchronizing the period of the triangular wave-shaped reference signal SS with the rotational speed of the generator (i & quasi-signal in the reference signal forming circuit 4). When forming the SS, the frequency of the output voltage of the generator is directly used to create a triangular wave-like reference fs.
You will be able to obtain the SS number.

In such an automatic voltage regulator, the voltage comparator CMPI in the switching control circuit 5 compares the integrated detection signal T-DS with the base 1 signal SS, and at that time, the output voltage of the generator changes to a higher level. ” then I-DS>S
When it comes to the relationship S, comparison 8: ÷ The time that the CMPI output is at low level becomes longer, and as a result!・The time that transistor Q2 is turned off becomes longer, and the field coil F
Switching control is performed so that the time for cutting off the field 1 current flowing through -CL becomes longer, and the output voltage of the generator is automatically controlled to decrease.

In addition, the output voltage of the generator fluctuates to a low level and T-DS<S
When the relationship S occurs, the time during which the output of the comparator CMPI is inverted to high level becomes longer, which increases the time during which transistor Q2 is on, and the field winding F
Switching control is performed so that the time for supplying the field current ■f to -CL is extended, and the output voltage of the generator is automatically controlled to decrease.

At this time, as shown in FIG. 3, when the level of the detection signal DS becomes low as shown by DS', the deviation is
1, the on time of the transistor Q2 for switching control of the field current if increases from 11 to tbi, and the off time decreases from t2 to t2'.

Furthermore, when the level of the detection signal DS becomes high as shown by DS', the deviation is amplified to I-DS' by the integrating circuit 11, and the on-time of the transistor Q2 for switching control of the field current If changes from tl to tl''. As well as decreasing to
Off time increases from 12 to 12''.

In this way, feedback control is continued to output the voltage value Vds of the detection signal Ds to be equal to the voltage value Vis at the reference point of integration, thereby suppressing fluctuations in the output voltage.

According to the present invention, the detection signal DS smoothed to a level with almost no pulsation is compared with the triangular wave base I (1! signal SS) synchronized with the frequency of the output voltage of the generator. Because I'm doing it.

Even if waveform distortion occurs in the output voltage of the generator, the detection signal D
Since S is smoothed to a level with almost no pulsation, switching control of the field current f in response to fluctuations in the output voltage of the generator can be performed stably without being affected by waveform distortion of the output voltage. You will be able to do this.

Further, an integration circuit 11 is provided between the variable resistor VR and the voltage comparator CMPI, and the detection signal DS is applied to the comparison input side of the amplifier OP-AMPI, and an integration circuit 11 is provided to integrate the detection signal O8. The voltage comparator CMP1 compares the detection signal I-DS integrated by the circuit 11 and the triangular wave reference signal SS, which greatly reduces the voltage fluctuation rate of the generator output voltage during pressure adjustment. It will be possible to reduce the

In that case, the amplifier ○P-
In order to drive the output of AMP 1, the detection winding DU
-CL, DV-CL, DW-CL4. : If the waveform factor (=effective value/average value) of each detected output at is the same in the case of no load of the generator and the case of rated load, the voltage fluctuation rate in the output voltage of the generator becomes zero.

The field current suppression circuit 12 determines the field current flowing through the field winding fi F -CL when the transistor Q2 is on. I!
The voltage generated in the current detection resistor R24 according to the current f is amplified by the operational amplifier OP-AMP2, and when the amplified output exceeds a predetermined value during overload, the transistor Q6 is turned on, and the voltage is integrated by the operational amplifier OP-AMP2. A resistor R30 is connected in series with the capacitor C4 in the circuit 11, so that the reference positive voltage Vis of the amplifier OP-AMPI is forcibly lowered.

Therefore, when the transistor Q2 is turned on and the field current If is supplied, the amplifier O in the integrating circuit 11
As the reference voltage Vis of P-AMPL decreases, the level of the integrated detection signal I-DS decreases to a predetermined level, and the field current If is regulated by the level decrease so that it does not increase beyond a certain level. be done.

That is, when the detection signal r-DS whose level has been lowered and the reference signal SS are compared in the voltage comparator CM P 1 and the switching control of the field current If is performed based on the comparison result, the integrated detection signal T- The on-time of the transistor Q2 is limited by the forced level reduction of DS6. Therefore, the increase in the field current If during overload is suppressed.

At that time, if the switch SW in the field current suppression circuit 12 is closed to the a contact side and the reference value of the operational amplifier OP-AMP2 is fixed, the field current with respect to the load current IL output from the generator The characteristics of 1F are as shown by A in FIG.

In the figure, Tfs indicates a limit value when the field current suppression circuit 12 operates to suppress an increase in the field current Tf when the load current IL is ILI.

In this case, as the load current IL exceeds TLI, the output of the operational amplifier OP-AMP2 increases, so the field current If decreases.

Further, the switch SW in the field current suppression circuit 12 is
When the contact side is closed, the characteristics of the field current If with respect to the load current of the generator are as shown by B in FIG. Note that the resistor R26 connects a signal with the same duty ratio as the duty ratio of the transistor Q2 to the operational amplifier O.
It is for sending out to the reference input side of P-AMP2, and in this case, even if the load current IL exceeds ILI, the field current If is maintained at the limit value Ifs.

Further, by appropriately selecting the value of the resistor R26, it is possible to change and adjust the downward slope of the linear characteristic portion B in FIG.

Then, the overload condition is resolved and the field current If decreases,
As a result, when the output voltage of the operational amplifier OP-AMP2 becomes lower than a predetermined value, the transistor Q6 is turned off. As a result, the amplifier ○P-A in the integrating circuit 11
The reference voltage Vis of MP 1 returns to normal, and the control by the field current suppression circuit 12 to suppress the increase in the field current If is canceled.

In the embodiment shown in FIG. 1, the field current suppression circuit 1
Integrating circuit 1 by turning on transistor Q6 at 2
A resistor R30 is connected in parallel with the capacitor C4 in 1, and the polarity inverting amplifier op-AMPI (7) jif; lowers the quasi voltage Vis to lower the level of the detection signal T-DS and the state in which the output voltage of the generator increases. Although the present invention is designed to reduce the appearance as when detected, the present invention is not limited to this configuration in any way.

For example, the transistor Q in the field current suppression circuit 12
6 is turned on, the resistor R30 is connected in parallel with the capacitor Ct in the smoothing circuit 2 to apparently lower the level of the detection signal DS, that is, the output voltage of the generator, in the same manner as described above.

It is possible to suppress an increase in the field current If during overload.

As described above, according to the present invention, by providing a field ffi current suppressing circuit, the field current If of the generator can be suppressed at the time of starting even for a load with a large starting current such as an electric motor.
This prevents the flow from exceeding the limit value Ifs, suppresses heat generation in the field winding F-CL, and optimizes the load on the electric motor while reducing the load on the drive source such as the engine. You will be able to start it.

In this case, in the present invention, instead of detecting an overload state due to a decrease in the output voltage of the generator and then executing control to suppress an increase in the field current If, the present invention directly passes the field current If. Since the increase in field current If is suppressed by detecting ff1i, it becomes possible to promptly cope with an increase in field current If during overload.

Further, according to the present invention, the output voltage of the generator is apparently lowered depending on the degree of overload, and the load can always be operated in an optimal state while suppressing an increase in the field current If. Good matching with the load is achieved.

As described above, in the automatic voltage regulator according to the present invention, the output voltage of the alternator which rectifies the output of the excitation winding and supplies field current to the field winding is detected by the detection winding, A detection signal obtained by rectifying and smoothing the detected voltage signal is compared with a reference signal, and based on the comparison result, switching control is performed on the field current so that the output voltage of the generator is constant. When the load state detection means detects the amount of field current flowing, and when the load state detection means detects that the field current has increased due to overload, the detection signal is set to the output voltage of the generator. This device is equipped with a means for level shifting 1- as when At the same time, it has the excellent advantage of reducing the load on the drive source and allowing operation to continue while maintaining that state until the overload state is resolved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an electric circuit diagram showing an embodiment of an automatic voltage regulator according to the present invention, and FIG. 2 is a time chart of signals 1-1-3 of each part in the reference signal forming circuit in the same embodiment. The figure is a time chart showing the on/off state of the switching element that turns on and off the field current based on a comparison between the detection signal and the reference signal in the same embodiment. It is a characteristic diagram of field current with respect to load current of a generator when control to suppress is executed.

1... Generator output detection circuit 2... Smoothing circuit 3.
・Detection signal formation circuit 4...Reference signal formation circuit 5.
... Switcher control circuit 6... Switching circuit 7... Pulse train signal forming circuit 8... Triangular wave signal forming circuit 9... Stabilizing power supply circuit 11... Integrating circuit 12... Field current suppression circuit F-CL...Field winding M-CL-...Output winding DU-CL, DV-CL
, DW-CL...detection winding EX-CL...excitation winding CMPI, CMP2...voltage comparator

Claims (1)

[Claims] 1. Detecting the output voltage of the alternator by rectifying the output of the excitation winding and supplying field current to the field winding by a detection winding, and rectifying the detected voltage signal. In an automatic voltage regulator that compares a detection signal obtained by smoothing a reference signal with a reference signal, and controls switching of a field current so that the output voltage of the generator is constant based on the comparison result, load state detection means for detecting the amount of magnetic current flowing; and when the load state detection means detects that the field current has increased due to overload, the detection signal is sent to the output voltage of the generator when the output voltage of the generator increases. An automatic voltage regulator characterized in that it is provided with means for level shifting as shown in FIG. 2. Apply the detection signal to the comparison input side of the amplifier in the integration circuit, integrate it, and compare the integrated detection signal with a triangular wave-like reference signal to adjust the field current so that the output voltage of the generator is constant. The automatic voltage adjustment according to item 1 above, characterized in that the automatic voltage adjustment is configured to perform switching control, and level-shift the reference signal on the reference input side of the amplifier according to the detection result by the load condition detection means. Device.