JPH0634636B2 - Time division control type automatic voltage regulator - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an automatic voltage regulator used for a synchronous generator or the like, and particularly when a time-division control circuit is used and the response speed is fast and the stability region is wide. The present invention relates to a split control type automatic voltage regulator.

[Prior Art and its Problems] FIG. 3 (A) shows a conventional automatic voltage regulator (hereinafter referred to as AVR).
Is shown.

1 is a synchronous generator, the output voltage of this synchronous generator 1 is supplied to the anode of a diode 4 via a transformer 2 and a reactor 3, and the output current of the synchronous generator 1 is a current transformer 5
Is supplied to the anode of the diode 4 through. The cathode side of the diode 4 is the field coil 1a of the synchronous generator 1.
And part of the output of the synchronous generator 1 is connected to the diode 4
Is rectified by and supplied for excitation. Further, as a constant voltage circuit of the synchronous generator 1, the output voltage is input to the voltage detector 7 via the transformer 6, and the detection voltage Vi by the voltage detector 7 is input to the voltage comparator 8.

In addition, the voltage comparator 8 has a set voltage from the voltage setter 9.
Vo is also input. The output signal of the voltage comparator 8 is the drive circuit 1
It is input to the gate of the thyristor 11 via 0. The anode side of the thyristor 11 is connected to the anode of the diode 4 via the resistor R1, and the cathode of the thyristor 11 is connected to the bypass resistor R2 of the field coil 1a.

In this constant voltage circuit, the detected voltage Vi from the voltage comparator 7 corresponding to the output voltage of the synchronous generator 1 is
Is compared with the set voltage from the voltage setter 9 and Vo,
When the detected voltage Vi is higher than the set voltage Vo, the voltage comparator 8 sends a predetermined signal to the drive circuit 10. As a result, the thyristor 11 becomes conductive by the drive signal from the drive circuit 10, the power supplied to the exciting coil 1a is bypassed by the resistor R2, and the output voltage of the synchronous generator 1 is suppressed and kept constant. .

In the above-described thyristor switching AVR, the thyristor 11 needs to be cut off when the gate signal to the thyristor 11 disappears, and therefore the thyristor 11 is inserted in the AC circuit.

Therefore, the switching frequency of the thyristor 11 also matches the output frequency of the synchronous generator 1, and since the synchronous generator 1 is present in the loop for voltage control described above, the time chart of FIG. 3 (B) is shown. As shown by, the control time constant also becomes large and a detection delay occurs. Further, since the exciting current includes a ripple of the output frequency of the generator, its control becomes unstable.

FIG. 4 (A) shows an AVR circuit of a transistor switching system, in which the switching transistor 20 is inserted on the DC side, that is, the cathode side of the diode 4, and 21 and 22 drive the switching transistor 20. The field currents detected by the field current detector 24 are input to the drive circuit 10 via the detection circuit 25.

In this transistor switching type AVR, since switching is performed on the DC side, the switching frequency can be set arbitrarily, and the control loop also constitutes a minor loop, as shown in the time chart of FIG. 4 (B). In addition, the control time constant is improved and reduced, and the detection delay is reduced, but since the ON operation and the OFF operation of the switching transistor 20 are controlled together, the control system becomes complicated,
Further, since a bipolar transistor is operated at a high speed as a switching transistor, a plurality of driving circuits are required, which results in a high device cost.

An object of the present invention is to eliminate the above-mentioned problems, and to provide a time-division control type automatic voltage regulator which improves the stability of the control system and simplifies the switching circuit. With the goal.

[Configuration of the Invention] The present invention is a time-division control type automatic voltage regulator that holds an output voltage constant by controlling the exciting current of a self-excited synchronous generator (1) in a time-division manner. Voltage detection means (6) for detecting the output voltage of the machine (1) and a rectifier for rectifying the voltage detected by the voltage detection means (6) to direct current
(12) and means for taking the difference voltage (Vi-Vo) between the output voltage (Vi) of the rectifier (12) and the set voltage (Vo), and taking in the feedback voltage (Vf) described later to reduce the difference voltage. (13) and the means (13)
Positive voltage depending on whether the output voltage of the integrator (14) exceeds the specified value and the output voltage of the integrator (14)
(VH), a comparator (15) that outputs a negative voltage (VL), and the exciting current supplied to the generator (1) is shunted by turning on from OFF by applying the positive voltage (VH). Power MOS
Only when the FET (16) and the positive voltage (VH) are output,
And a resistance voltage dividing circuit (R3, R4) provided so that (VH) can be supplied as the feedback voltage (Vf).

[Key point of the invention] Of the on / off operations in the switching control, the off-control of the on / off operation is performed by forming a circuit simulating the controlled object in the control circuit and using the signal to speed up the response speed of the control system and stabilize the operation. The focus is on increasing the degree. That is, the voltage difference (Vi) between the detected voltage (Vi) of the generator (1) and the set voltage (Vo).
-Vo) is integrated by the integrator (14), and the positive voltage (VH) output from the comparator (15) when the integrated value reaches the specified value.
Therefore, by switching on the power MOSFET (16), the exciting current supplied to the generator is shunted, while the positive voltage (VH) is used as a feedback voltage to reduce the differential voltage (Vi-Vo). As a result, as a result of the integrated value of the integrator (14) falling below the specified value, the negative voltage (VL) output from the comparator (15) switches off the power MOSFET (16) to turn off the excitation. Stop current diversion. comparator
When (16) outputs a negative voltage (VL), the feedback voltage is no longer supplied to the means (13), so that after this,
The integrator (14) restarts the integration to repeat the above-mentioned operation. In this way, power MO is time-divisionally
The output voltage of the generator (1) is kept constant by turning on and off the SFET (16) and shunting the exciting current to the generator (1).

[Embodiment] FIG. 1A shows an embodiment of the present invention, in which the same parts as those in the conventional example are designated by the same reference numerals.

The output voltage of the synchronous generator 1 passes through the transformer 6 and the rectifier 12
Is input to the adder 13 as a detection voltage Vi representing the output voltage of the synchronous generator 1 and added to the adder 13. The set voltage Vo from the voltage setter 9 is subtracted and input to the adder 13, and the feedback voltage Vf from the regulator 18 described later is added and input.

The output voltage of the adder 13 is input to the integrator 14, and the integrated voltage of the integrator 14 is input to the comparator 15. The output voltage of the comparator 15 is input to the gate of the power MOSFET 16 and also to the inverter 17. The drain of the power MOSFET 16 is connected to the cathode of the diode 4, and the exciting current of the synchronous generator 1 is connected to the power MOSFET 16 so as to be shunted. On the other hand, the output portion of the inverter 17 is connected to the input portion of the regulator 18 via the resistor R3 and also to the resistor R4, and the output voltage VL is applied to the other end of the resistor R4.

Next, the operation of the circuit configuration described above will be described with reference to the time charts of FIGS.

The detected voltage Vi from the rectifier 12 is compared with the set voltage Vo from the voltage setter 9 and the voltage Vf of the feedback signal from the regulator 18 in the adder 13, and the difference voltage is integrated by the integrator 14.

Now, when the output voltage of the synchronous generator 1 exceeds the rated voltage, that is, when the detection voltage Vi exceeds the set voltage Vo as shown in FIG. 2 (A) (time point t _{1 to} t ₂ ). , Fig. 2 (B)
As shown by, the difference voltage having a value exceeding that is output from the adder 13. The feedback voltage Vf at this time is 0V as described later.

The output voltage of the adder 13 is integrated by the integrator 14, rises with time as shown in FIG. 2 (C), and reaches Vb (time t ₂ ), the comparator 15 operates, and the second
As shown in the figure (D), the output level is switched from the negative voltage VL to the positive voltage VH. Power by this
The MOSFET 16 is turned on, and the exciting current supplied to the field coil 1a through the diode 4 is supplied to the power MOSFET 16a.
The output voltage of the synchronous generator 1 decreases as shown in FIG. 2 (E). At this time t ₂ ,
The positive voltage VH output from the comparator 15 is inverted into a negative voltage VL by the inverter 17, and the voltage VL is applied to one end of the resistor R3, but the voltage VL is applied to one end of the resistor R4.
Is applied, the potential at the connection point between the resistors R3 and R4 is also VL, and this negative voltage VL is adjusted to a predetermined voltage value by the regulator 18, and is fed to the adder 13 as the feedback voltage Vf. Input is added.

Since the feedback voltage Vf at this time is a negative value, the output voltage of the adder 13 decreases and a negative voltage is output, as shown at times t _{2 to} t ₃ in FIG. 2 (B). As a result of integrating the negative voltage by the integrator 14, when the integrator output decreases with time as shown by time points t _{2 to} t ₃ in FIG. ₃ ), the comparator 15 outputs the negative voltage VL. As a result, the power MOSFET 16 is cut off, so that the current supplied through the diode 4 flows only in the field coil 1a, and the output voltage of the synchronous generator 1 is also restored.

At this time t ₃ , the voltage VL output from the comparator 15 is inverted by the inverter 17 into the positive voltage VH, and the voltage VH is applied to the resistor R3. Now, when the absolute values of the voltages VH and VL are equal and the resistance values of the resistors R3 and R4 are equal, the potential of the connection point divided by the resistors R3 and R4 becomes just 0V, The feedback voltage Vf from the adjuster 18 also becomes 0V and has no effect on the adder 13.

At this point t _3, when exceeds still than the detection voltage Vi is set potential Vo from the rectifier 12, the same control as described above again, as shown at time t ₃ or later is performed.

As described above, the period from time t ₁ to t ₂ is a period in which the exciting current is not shunted during the off period of the power MOSFET 16, and the time t ₂
Period ~t ₃ is a on-period of the power MOSFET 16, a period in which the output voltage of the synchronous generator 1 is reduced by shunting the excitation current.

By the way, as shown in FIG. 2 (A), the period between time points t ₁₁ and t ₁₃ is higher than the detected voltage during the time period between t _{1 and} t _3.
This is when Vi exceeds the set voltage Vo by a large amount, and at this time, as shown in FIG. 2 (C), the time t ₁₂ to t ₁₁ when the integrator output rises from Va to Vb (non-diversion period). Is short, and conversely, the time t ₁₃ to t ₁₂ (diversion period) for decreasing from Vb to Va is long. As can be seen from this, the output voltage reduction period of the synchronous generator 1 is set corresponding to the voltage value that exceeds the rated voltage of the synchronous generator 1. In this way, the control loop composed of the integrator 14, the comparator 15, the inverter 17, and the adjuster 18 constitutes a circuit simulating the controlled object, whereby the control for keeping the average output voltage of the synchronous generator 1 constant. Is done.

FIG. 1 (B) is a time chart showing the control operation described above. Both the detection delay and the control time constant are small, the response is good, and the field current is time-divisionally switched at high speed. , The field current is controlled smoothly, and as described above, the control system imitating the controlled object eliminates external factors that disturb the control system, and the stability of the control system is significantly improved. . Further, since the power MOSFET is used as the switching element, the drive circuit of the power MOSFET is simplified.

[Effects of the Invention] As described above, in order to keep the output voltage constant, the present invention controls the exciting current of the generator by turning on and off the power MOSFETs provided in the exciting circuit in a time sharing manner at high speed. Therefore, the field current is smoothly controlled, and the stability of the control system is improved.

[Brief description of drawings]

FIG. 1 (A) is a block diagram of a voltage regulator showing one embodiment of the present invention, FIG. 1 (B) is a time chart showing the operation in FIG. 1 (A), and FIGS. E) is a diagram showing each output waveform in FIG. 1 (A), FIG. 3 (A) and FIG. 4 (A) are block diagrams of a conventional voltage regulator, FIG. 3 (B) and FIG. (B) is a time chart showing the operation in FIG. 3 (A) and FIG. 4 (A), respectively. 1 ... Synchronous generator, 9 ... Voltage setting device 12 ... Rectifier, 13 ... Adder 14 ... Integrator, 15 ... Comparator 16 ... Power MOSFET, 17 ... Inverter 18 ... Regulator, R3 , R4 ... resistor

Claims (1)

[Claims] 1. A time-division control type automatic voltage regulator for maintaining a constant output voltage by controlling an exciting current of a self-excited synchronous generator (1) in a time-division manner, the generator (1) Voltage detecting means (6) for detecting the output voltage of and a rectifier for rectifying the voltage detected by the voltage detecting means (6) into direct current
(12), and means for taking the difference voltage (Vi-Vo) between the output voltage (Vi) of the rectifier (12) and the set voltage (Vo), and taking in the feedback voltage (Vf) described later to reduce the difference voltage. (13) and the means (13)
Positive voltage depending on whether the output voltage of the integrator (14) exceeds the specified value and the output voltage of the integrator (14)
(VH), a comparator (15) that outputs a negative voltage (VL), and the exciting current supplied to the generator (1) is shunted by turning on from OFF by applying the positive voltage (VH). Power MOS
Only when the FET (16) and the positive voltage (VH) are output,
A time division control type automatic voltage regulator, comprising: a resistance voltage dividing circuit (R3, R4) provided so that (VH) can be supplied as the feedback voltage (Vf).