JPH10313599A - Automatic voltage regulator for synchronous or brushless synchronous generators - Google Patents

Abstract

(57) Abstract: To provide an automatic voltage generator for a synchronous generator capable of stably controlling an output voltage by canceling a change in an excitation voltage accompanying a change in the rotation speed of the synchronous generator. An operational amplifier that amplifies an error signal between a voltage detector and a voltage command signal generator and outputs a control signal for compensating fluctuations in generator characteristics, and a rotation output by a rotation speed detector of a synchronous generator. A divider that divides the control signal output from the operational amplifier by the number detection signal, a pulse width modulator that outputs an on-duty switching signal proportional to the output signal of the divider, and the same rotation axis as the rotor of the synchronous generator A power converter for supplying an excitation voltage to a field winding of the synchronous generator by opening and closing a DC voltage for converting an AC voltage output from the permanent magnet generator on the basis of a switching signal and operating a chopper. Therefore, when the rotational speed of the synchronous generator changes, the terminal voltage of the synchronous generator can be adjusted to a desired voltage while canceling the change in the excitation voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention utilizes the output terminal voltage of a permanent magnet generator coaxial with the rotor of a synchronous generator or a brushless synchronous generator as the excitation voltage of the synchronous generator or the brushless synchronous generator. The present invention also relates to an automatic voltage regulator for a synchronous generator or a brushless synchronous generator that automatically controls an output terminal voltage of the synchronous generator or the brushless synchronous generator to a desired voltage.

[0002]

2. Description of the Related Art FIG. 4 is a configuration diagram of an automatic voltage regulator of a synchronous generator as an example of a conventional power generator. In the figure, 1 is a synchronous generator, 2 is a permanent magnet generator (hereinafter referred to as PMG) installed coaxially with the rotor of the synchronous generator 1, 3 is an automatic voltage regulator, and 1 is a synchronous generator. This device automatically controls the output terminal voltage Vg of the synchronous generator 1 to a desired voltage by manipulating the voltage Vf applied to the field winding.

[0003] The automatic voltage regulator 3 comprises a synchronous generator 1
A voltage detector 10 for detecting a voltage of the output terminal of the inverter and outputting a detection signal A, a voltage command signal generator 11 for generating a voltage command signal B, and subtracting the detection signal A and the voltage command signal B to obtain an error between the two. , An operational amplifier 13 that amplifies the error signal C output from the subtractor 12 and outputs a control signal that compensates for variations in generator characteristics due to variations in load impedance and the like, and an output of the operational amplifier 13. A pulse width modulator 14 that outputs an on-duty switching signal E proportional to the control signal D, a transformer 20 that steps down the output terminal voltage Vss of the PMG2, and an AC voltage supplied from the transformer 20 to a DC voltage. A rectifier 21 for converting, and opening and closing a transistor based on the switching signal E;
It comprises a power converter 22 for adjusting the exciting voltage Vf supplied to the field winding of the synchronous generator 1 by chopper operation of the DC voltage supplied from the rectifier 21.

[0004] Such a power generating device uses the output terminal voltage of a PMG 2 installed coaxially with the rotor of the synchronous generator 1 as a power source for the excitation voltage of the synchronous generator 1.
It is said to be a G excitation type power generator.

FIG. 5 is a block diagram showing the function of the power generator shown in FIG. 4, and the same parts as those in FIG. Also, the signals A to F, Vf, and Vg in FIG.
Both are p. u. Values (hereinafter referred to as pu values).

In FIG. 5, a voltage detector 10 outputs a detection signal A of an output terminal voltage of the synchronous generator 1, a voltage command signal generator 11 outputs a voltage command signal B, and a subtractor 12 outputs a detection signal A. The operational amplifier 13 outputs an error signal C by amplifying the error of the voltage command signal B, and outputs a control signal D for amplifying the error signal C and compensating for a change in generator characteristics due to a change in load impedance or the like, The pulse width modulator 14 outputs a switching signal having an on-duty F proportional to the control signal D. Note that the rectifier 21 in FIG. 4 outputs a DC voltage proportional to the output terminal voltage Vss of the PMG2, and a block diagram is omitted.

The multiplier 23 represents the function of the power converter 22 shown in FIG.
Is multiplied by the pu value Vss (pu) of the output terminal voltage Vss of the PMG 2, and the pu value Vf of the excitation voltage Vf of the synchronous generator 1 is obtained.
(Pu) is output. Here, the output terminal voltage Vss0 of the PMG at the time of rated rotation is designed to be a voltage larger than the excitation voltage Vf0 at the time of the no-load rated operation of the ordinary synchronous generator 1 (that is, the rated excitation voltage), and Vss0 = Vf0 × K. The output terminal voltage Vss of the PMG is substantially proportional to the rotation speed ω of the synchronous generator 1, and the pu value of ω is changed to ω (p
u), Vss = ω (pu) × Vss0.

The pu value of Vss, Vss (pu), is obtained by calculating
Expressed as a pu value based on f0,

(Equation 1) Is defined by

The excitation voltage Vf (pu) of the synchronous generator 1 is given by Vf (pu) = Vss (pu) × F. The on-duty F is given by F = D × f ₁₄ where f ₁₄ is a proportional function of the pulse width modulator 14.

Accordingly, the function from the control signal D to the excitation voltage Vf (pu) of the synchronous generator 1 is Becomes In the rated operation state, since ω (pu) = 1.0, the excitation voltage Vf (pu) is a voltage proportional to the control signal D.

As described above, the excitation circuit of the power generator of the PMG excitation system is equivalent to the function of the power converter 22 multiplying the output terminal voltage Vss of the PMG 2 by the switching signal F output from the pulse width modulator 14. To fulfill the function,
As shown in FIG. 5, a multiplier 23 is included in the control block diagram.

In FIG. 5, the functions of a voltage detector 10, a voltage command signal generator 11, a subtractor 12, an operational amplifier 13, and a pulse width modulator 14 are performed by a microcomputer and software executed by the microcomputer. Can be realized. Further, a brushless generator may be connected to the automatic voltage regulator 2 instead of the synchronous generator 1.

FIG. 6 is a configuration diagram of another conventional power generator. The difference between this power generation device and the power generation device of FIG. 4 that has already been described is that the configuration of the automatic voltage regulator 4 is such that the automatic voltage regulator 3 of FIG. Instead of providing the modulator 14, the rectifier 21, and the power transformer 22, a phase in which the AC voltage supplied from the transformer 20 is ignited based on the thyristor rectifier 25 and the control signal D output from the operational amplifier 13. Since the present embodiment is provided with the controller 24 and the other points are the same, the same parts are denoted by the same reference numerals and the description thereof will not be repeated.

The automatic voltage regulator 4 of the power generator controls the generator excitation voltage by rectifying the AC voltage supplied from the transformer 20 by the thyristor rectifier 25 as described above. The thyristor rectifier 25 is configured to perform the function of a multiplier just like the automatic voltage regulator of the above.

[0015]

In the above-described conventional power generator, when the rotation speed of the synchronous generator or the brushless synchronous generator fluctuates and the automatic voltage regulator performs automatic control for suppressing the fluctuation, Since the output voltage Vss of the PMG, which is the excitation power supply, also fluctuates at the same time, the excitation voltage Vf of the synchronous generator or the brushless synchronous generator includes an error corresponding to the fluctuation of Vss. In other words, in FIG. 5, the automatic voltage regulator 3 controls the excitation voltage V of the synchronous generator or the brushless synchronous generator in proportion to the control signal D output from the operational amplifier 13.
f cannot be output.

The stability of the control system is generally designed on a Bode diagram, but the Bode diagram holds for a linear control system. As shown in the configuration diagram, this is not an effective method for a non-linear control system including a multiplier, but usually, the excitation power supply voltage accompanying the rotation speed fluctuation of the synchronous generator or the brushless synchronous generator as described above. In many cases, the design is performed on a Bode diagram by ignoring the fluctuation and approximating that the excitation power supply voltage is always constant. In such a case, since the designer cannot clearly understand how much the error due to the fluctuation of the excitation power supply voltage actually affects the stability of the control system, the operation of the synchronous generator or the brushless synchronous generator is not possible. Sometimes the generator voltage may be unstable.

The present invention (corresponding to claims 1 to 8) provides
In order to eliminate the above-mentioned drawbacks of the conventional PMG excitation type automatic voltage regulator, the fluctuation of the excitation power supply voltage accompanying the rotation speed fluctuation of the synchronous generator or the brushless synchronous generator is offset,
Automatic voltage regulator for synchronous generators or brushless synchronous generators capable of stably controlling the output terminal voltage of a synchronous generator or brushless synchronous generator by obtaining a generator excitation voltage proportional to the control signal of the automatic voltage regulator The purpose is to provide.

[0018]

According to a first aspect of the present invention, there is provided an automatic voltage regulator for a synchronous generator, comprising: a voltage detector for detecting a terminal voltage of the synchronous generator; A voltage command signal generator for generating a voltage command signal for a generator, a subtractor for calculating an error between a detection signal output from the voltage detector and a voltage command signal output from the voltage command signal generator, and the subtractor An operational amplifier that amplifies the error signal output from the synchronous generator and outputs a control signal for compensating for variations in generator characteristics due to variations in load impedance, etc., and detects a rotation speed of the synchronous generator and outputs a rotation speed detection signal. A rotation speed detector, a divider for dividing a control signal output from the operational amplifier by a rotation speed detection signal output from the rotation speed detector, and on-duty switching proportional to the output signal of the divider A pulse width modulator that outputs a signal, a permanent magnet generator that is on the same rotation axis as the rotor of the synchronous generator, a rectifier that converts an AC voltage output by the permanent magnet generator into a DC voltage, A power converter that supplies an exciting voltage to a field winding of the synchronous generator by chopper-operating a DC voltage output from a rectifier by a switching element that is opened and closed according to the switching signal, wherein the divider performs the arithmetic operation. When the rotation speed of the synchronous generator fluctuates by dividing the control signal output from the amplifier by the rotation speed detection signal, the terminal voltage of the synchronous generator is reduced to a desired voltage while canceling the fluctuation of the excitation voltage. It is characterized by adjusting to.

According to a second aspect of the present invention, in the automatic voltage regulator for a synchronous generator according to the first aspect, a brushless synchronous generator is provided in place of the synchronous generator, and the rotational speed of the brushless synchronous generator varies. In this case, the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage.

According to a third aspect of the present invention, in the automatic voltage regulator for a synchronous generator according to the first aspect, a thyristor rectifier and a thyristor rectifier are used instead of the rectifier, the pulse width modulator, and the power converter. A phase controller for controlling an arc phase, wherein when the rotation speed of the synchronous generator fluctuates, the terminal voltage of the synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage. And

According to a fourth aspect of the present invention, in the automatic voltage regulator for a synchronous generator according to the third aspect, a brushless synchronous generator is provided instead of the synchronous generator, and the number of revolutions of the brushless synchronous generator varies. In this case, the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage.

According to a fifth aspect of the present invention, in the automatic voltage regulator for a synchronous generator according to the first aspect, the voltage command signal generator, the subtractor, the operational amplifier, the divider, and the pulse width modulator are provided. Function is realized by a microcomputer and software executed by the microcomputer. When the rotation speed of the synchronous generator fluctuates, the terminal voltage of the synchronous generator is reduced to a desired voltage while canceling the fluctuation of the excitation voltage. It is characterized by adjusting to.

According to a sixth aspect of the present invention, in the automatic voltage regulator for a synchronous generator according to the fifth aspect, a brushless synchronous generator is provided instead of the synchronous generator, and the rotation speed of the brushless synchronous generator varies. In this case, the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage.

According to a seventh aspect of the present invention, there is provided the automatic voltage regulator for a synchronous generator according to the third aspect, wherein the voltage command signal generator, the subtractor, the operational amplifier, the divider, and the phase controller are connected to each other. The functions are realized by a microcomputer and software executed by the microcomputer, and when the rotation speed of the synchronous generator fluctuates, the terminal voltage of the synchronous generator is set to a desired voltage while canceling the fluctuation of the excitation voltage. It is characterized by adjusting.

According to an eighth aspect of the present invention, in the automatic voltage regulator for a synchronous generator according to the seventh aspect, a brushless synchronous generator is provided in place of the synchronous generator, and the rotation speed of the brushless synchronous generator varies. In this case, the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of an embodiment (corresponding to claims 1, 2, 5, and 6) of the present invention.

As shown in the figure, the present embodiment is different from the conventional generator shown in FIG. 4 in that the configuration of the automatic voltage regulator 5 is different from that of the conventional generator shown in FIG. Rotation speed detector 16 which detects rotation speed by a rotation speed detection sensor 17 and outputs a rotation speed detection signal G;
Is provided only by the point that a divider 15 for dividing the control signal D output from the control signal D by the rotation speed detection signal G output from the rotation speed detector 16 is provided. And a duplicate description is omitted.

The functions of the voltage command generator 11, the subtractor 12, the operational amplifier 13, the pulse width modulator 14, and the divider 15 among the components constituting the automatic voltage regulator 5 are the same as those of the microcomputer. And software executed by this microcomputer.

FIG. 2 is a block diagram showing the functions of the synchronous generator 1 or the automatic voltage regulator 5 of the brushless synchronous generator shown in FIG. In the figure, a voltage detector 10 outputs a detection signal A of an output terminal voltage of the synchronous generator 1 or the brushless synchronous generator, and a voltage command signal generator 11 outputs a voltage command signal B. The subtractor 12 calculates an error between the detection signal A and the voltage command signal B and outputs an error signal C. The operational amplifier 13 amplifies the error signal C and compensates for a change in generator characteristics due to a change in load impedance. The control signal D is output. Further, the rotation number detector 16 detects the rotation number of the synchronous generator 1 or the brushless synchronous generator and outputs a rotation number detection signal G to the divider 15, and the divider 15 divides the control signal D by the detection signal G. The output signal H is output. The pulse width modulator 14 outputs a switching signal having an on-duty F ′ proportional to the signal H output from the divider 15.

Since the rectifier 21 of FIG. 1 outputs a DC voltage proportional to the output terminal voltage Vss of the PMG 2, the block is omitted. The multiplier 23 represents the function of the power converter 22 shown in FIG. 1, and multiplies the on-duty F 'of the switching signal by the pu value Vss (pu) of the output terminal voltage VSS of the PMG2 to generate the synchronous generator 1 or It outputs Vf (pu) of the pu value of the excitation voltage Vf of the brushless synchronous generator.

Next, the operation of the present embodiment will be described.
Normally, in a steady state, the output terminal voltage Vg (pu) of the synchronous generator 1 or the brushless synchronous generator is controlled to be the voltage command signal B output from the voltage command signal generator 11, and the error signal C Is zero. If Vg (pu) fluctuates for a certain time, an error occurs between the voltage command signal B and the detection signal A, and the error signal C
Is output. The operational amplifier 13 amplifies the error signal C and outputs a control signal D for compensating for variations in generator characteristics due to variations in load impedance. Rotation speed detector 16
Detects the rotation speed of the synchronous generator 1 or the brushless synchronous generator and outputs a rotation speed detection signal G. The divider 15 divides the control signal D by the rotation speed detection signal G and outputs a phase signal H. The pulse width modulator 14 outputs a square wave switching signal having an on-duty F ′ proportional to the phase signal H. The multiplier 23 shows the function of the power converter 22 of FIG.
The pulse width modulator 14 is connected to the PMG output terminal voltage Vss (pu).
, The excitation voltage Vf (pu) is supplied to the synchronous generator 1 or the field winding of the brushless synchronous generator.
Here, the PMG output terminal voltage Vss0 during the rated rotation is designed to be higher than the excitation voltage (ie, the rated excitation voltage) Vf0 during the no-load rated operation of the normal synchronous generator 1 or the brushless synchronous generator. Therefore, Vss0 = Vf0 × K. The output terminal voltage Vss of the PMG is the synchronous generator 1
Or approximately proportional to the rotational speed ω of the brushless synchronous generator,
Assuming that the pu value of ω is ω (pu), Vss = ω (pu) × Vss0. The pu value of Vss, Vss (pu), is obtained by calculating
By expressing by a pu value based on f0,

(Equation 2) Is defined by

By the above-described operation, even when the rotational speed of the generator fluctuates, the fluctuation of the excitation power supply voltage of the synchronous generator is canceled. That is, in FIG. 2, the excitation voltage Vf (pu) of the synchronous generator 1 or the brushless synchronous generator
Is given by the following equation. Vf (pu) = Vss (pu) × F ′

Here, the output terminal voltage Vss (p
u) is substantially proportional to the rotational speed ω (pu) of the synchronous generator 1 or the brushless synchronous generator, and is expressed by the following equation. Vss (pu) = ω (pu) × K

Further, on-duty F 'is a proportionality function of the pulse width modulator 14 and f _14,

(Equation 3) The function from the control signal D to the excitation voltage Vf (pu) of the synchronous generator 1 or the brushless synchronous generator is
omega (pu) and the rotation speed detecting signal G is canceled out, Vf (pu) = D × f 14 × K , and the synchronization is proportional to the control signal D generator or brushless synchronous generator excitation voltage Vf (pu) is can get.

FIG. 3 shows another embodiment of the present invention.
It is a block diagram of Claim 4, Claim 7, and Claim 8). This embodiment is different from the power generator of FIG. 1 in that the configuration of the automatic voltage regulator 6 of the present embodiment is such that the automatic voltage regulator 5 of FIG. 1 performs a chopper operation on the AC voltage supplied from the transformer 20. Instead of providing the pulse width modulator 14, the rectifier 21, and the power converter 22, the AC voltage supplied from the transformer 20 is fired based on the thyristor rectifier 23 and the control signal D output from the operational amplifier 13. And the other points are the same. Therefore, the same parts are denoted by the same reference numerals and the repeated description will be omitted.

In the automatic voltage regulator 6 of the synchronous generator 1 or the brushless synchronous generator of the present embodiment, the pulse width modulator 14 for chopper-operating the AC voltage supplied from the transformer 20 as in the embodiment of FIG. Only the point that a thyristor rectifier 23 and a phase controller 24 for firing the thyristor rectifier are provided instead of providing the thyristor rectifier and the rectifier 21 and the power converter 22 is different from the embodiment of FIG. The same functions as in the block diagram of FIG. That is, the excitation voltage Vf (pu) of the synchronous generator or the brushless synchronous generator proportional to the control signal D is obtained as in FIG.

[0037]

As described above, the present invention (Claim 1)
According to claim 8), when the output terminal voltage of the synchronous generator or the brushless synchronous generator of the PMG excitation system is controlled by the automatic voltage regulator, fluctuations in the rotation speed of the synchronous generator or the brushless synchronous generator may be prevented. Since the accompanying fluctuation of the excitation power supply voltage can be canceled out and a synchronous generator or a brushless synchronous generator field voltage proportional to the control signal of the automatic voltage regulator can be obtained, the synchronous generator or the brushless synchronous generator can be obtained more than in the prior art. The output terminal voltage can be controlled stably.

In addition, the control system becomes a linear system in order to eliminate the function of the multiplier which the PMG excitation type synchronous generator or the brushless synchronous generator basically includes, and the control design on the Bode diagram becomes effective. It is possible to provide a power generation device that can be easily designed.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing the functions of the automatic voltage regulator shown in FIG. 1;

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

FIG. 4 is a configuration diagram of a conventional power generation device.

FIG. 5 is a block diagram showing the functions of the automatic voltage regulator of FIG. 4;

FIG. 6 is a configuration diagram of another conventional power generation device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Synchronous generator, 2 ... PMG, 3, 4, 5, 6 ... Automatic voltage regulator, 10 ... Voltage detector, 11 ... Voltage command signal generator, 12 ... Subtractor, 13 ... Operational amplifier, 14 ... Pulse Width modulator, 15: divider, 16: rotational speed detector, 17 ...
Rotation speed detection sensor, 20: transformer, 21: rectifier, 22
... power converter, 23 ... multiplier, 24 ... phase controller, 25
... Thyristor rectifier.

Claims (8)

[Claims] 1. A voltage detector for detecting a terminal voltage of a synchronous generator, a voltage command signal generator for generating a voltage command signal for the synchronous generator, a detection signal output from the voltage detector, and the voltage command A subtracter for calculating an error of the voltage command signal output from the signal generator; and a control signal for amplifying the error signal output from the subtractor and compensating for a change in generator characteristics due to a change in load impedance. An operational amplifier, a rotational speed detector that detects the rotational speed of the synchronous generator and outputs a rotational speed detection signal, and divides a control signal output by the operational amplifier by a rotational speed detection signal output by the rotational speed detector. Divider, a pulse width modulator that outputs an on-duty switching signal proportional to the output signal of the divider, a permanent magnet generator that is on the same rotation axis as the rotor of the synchronous generator, A rectifier that converts an AC voltage output from the permanent magnet generator into a DC voltage, and a switching element that opens and closes the DC voltage output by the rectifier according to the switching signal to perform a chopper operation, thereby forming a field winding of the synchronous generator. A power converter for supplying an exciting voltage to a line, wherein the divider divides a control signal output from the operational amplifier by the rotation speed detection signal, thereby changing the rotation speed of the synchronous generator. An automatic voltage regulator for a synchronous generator, wherein the terminal voltage of the synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage. 2. The automatic voltage regulator for a synchronous generator according to claim 1, further comprising a brushless synchronous generator in place of said synchronous generator, wherein said excitation is performed when a rotation speed of said brushless synchronous generator fluctuates. An automatic voltage regulator for a brushless synchronous generator, wherein the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the voltage fluctuation. 3. The automatic voltage regulator for a synchronous generator according to claim 1, wherein a thyristor rectifier instead of said rectifier, said pulse width modulator, and said power converter controls a firing phase of said thyristor rectifier. A synchronous generator having a controller, wherein when the rotational speed of the synchronous generator fluctuates, the terminal voltage of the synchronous generator is adjusted to a desired voltage while canceling the fluctuation of the excitation voltage. Automatic voltage regulator. 4. The automatic voltage regulator for a synchronous generator according to claim 3, further comprising a brushless synchronous generator in place of said synchronous generator, wherein said excitation voltage is changed when a rotation speed of said brushless synchronous generator fluctuates. And adjusting the terminal voltage of the brushless synchronous generator to a desired voltage while canceling the fluctuation of the voltage of the brushless synchronous generator. 5. The automatic voltage regulator for a synchronous generator according to claim 1, wherein the functions of the voltage command signal generator, the subtractor, the operational amplifier, the divider, and the pulse width modulator are controlled by a microcomputer. It is realized by software executed by the microcomputer, and adjusts the terminal voltage of the synchronous generator to a desired voltage while canceling the fluctuation of the excitation voltage when the rotational speed of the synchronous generator changes. Automatic voltage regulator for synchronous generators. 6. The automatic voltage regulator for a synchronous generator according to claim 5, further comprising a brushless synchronous generator in place of said synchronous generator, wherein said excitation is performed when the rotation speed of said brushless synchronous generator fluctuates. An automatic voltage regulator for a brushless synchronous generator, wherein the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the voltage fluctuation. 7. The automatic voltage regulator for a synchronous generator according to claim 3, wherein the functions of the voltage command signal generator, the subtractor, the operational amplifier, the divider, and the phase controller are controlled by a microcomputer. It is realized by software executed by a microcomputer, and adjusts the terminal voltage of the synchronous generator to a desired voltage while canceling the fluctuation of the excitation voltage when the rotational speed of the synchronous generator fluctuates. Automatic voltage regulator for synchronous generators. 8. The automatic voltage regulator for a synchronous generator according to claim 7, further comprising a brushless synchronous generator in place of said synchronous generator, wherein said excitation is performed when the rotation speed of said brushless synchronous generator fluctuates. An automatic voltage regulator for a brushless synchronous generator, wherein the terminal voltage of the brushless synchronous generator is adjusted to a desired voltage while canceling the voltage fluctuation.