JP3129791B2 - Induction generator control - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor suitable for applications in which the rotation speed of a prime mover is greatly changed, such as wind power generation or shaft power generation in which electric power is obtained by using surplus power of a mechanical device used in an internal combustion engine. The present invention relates to a generator control device.

[0002]

2. Description of the Related Art FIG. 8 is a block diagram of a conventional example. In the figure, 1 is a prime mover, 2 is an induction generator driven by the prime mover 1, 3 is a converter for converting the AC output of the induction generator 2 to DC, 4 is a capacitor for smoothing the output voltage of the converter 3, 5 is an induction generator DC power supply for initial excitation of machine 2, 6
Is a circuit breaker for turning on and off the power supplied from the converter 3 to the load, and 7 is a load.

[0003] Reference numeral 8 denotes a current detector for detecting the output current of the induction generator 2, and 9 denotes a voltage detector for detecting the output voltage of the converter 3. 10 is a power generation operation command, 11 is a power generation start-up control circuit, 12 is a voltage control circuit for controlling the output voltage of the converter 3, 101 is a rotation detector for detecting the induction generator rotation speed, and 102 is a rotation detector 101. A slip frequency control circuit for controlling the magnitude of the output current of the induction generator 2 and the slip frequency based on the detected rotation speed of the induction generator 2, and a three-phase current 103 obtained as an output of the slip frequency control circuit 102. The command value 104 is a current control circuit for controlling the motor current detected by the current detector 8 to be equal to the three-phase current command value 103. The reference numeral 15 is a PWM control circuit for controlling the current control signal output from the current control circuit.
For outputting a drive signal of the switching element constituting the PW
M control circuit.

In the above-described conventional configuration, when the power generation operation command 10 is given, the start-up control circuit 11 outputs a power generation voltage command value to the voltage control circuit 12. Voltage control circuit 12
In the above, the generated voltage command value is compared with the output voltage of the converter 3 detected by the voltage detector 10, and the magnitude of the output current of the induction generator 2 and the slip frequency are controlled by the slip frequency control circuit 102 according to the deviation. You.

At the time of start-up, since the output voltage of converter 3 is lower than the generated voltage, the output current of the induction generator is increased, and the slip frequency is increased in the negative direction, so that the power generated by induction generator 2 is increased. I do. That is, the slip frequency control circuit 102 sets the instantaneous command value 10 of each phase current having an amplitude and slip corresponding to the deviation of the output voltage with reference to the rotation speed of the induction generator 2 detected by the rotation detector 101.
3 is calculated.

Next, in the current control circuit 104, the instantaneous value of each phase current of the induction generator 2 detected by the current detector 8 is compared with the instantaneous command value 103 of each phase current to make the current equal to the command value. A current control signal is obtained by performing control so that the PWM control circuit 105 converts the current control signal into a PWM signal to operate the converter, thereby controlling the output current of the induction generator 2. When the output voltage of converter 3 reaches the generated voltage command value, start-up control circuit 11 turns on circuit breaker 6 and starts supplying power to load 7.

When the generated voltage is about to drop due to the load 7 being turned on, the voltage control circuit 12, slip frequency circuit 102, current control circuit 104, PWM control circuit 1
The converter is controlled by 05 to increase the power generated by the induction generator 2 to keep the generated voltage constant. By controlling the power generated by the induction generator 2 in this manner, the output voltage of the converter 3 can be controlled to be constant irrespective of a change in the power consumption of the load 7.

[0008]

In the above-described conventional configuration, it is necessary to install a rotation detector near the prime mover 1. However, due to the bad environment of large vibration and high temperature / humidity, rotation detection is required. There were many troubles with the container 8. If the rotation detector fails, power generation cannot be continued, and the output signal of the rotation detector 8 is disturbed by vibration of the prime mover 1 or electromagnetic noise. Therefore, the output current of the derivative generator 2 controlled based on this is disturbed, and stable control cannot be performed. In addition, if the accuracy and resolution of the rotation detector 8 are low, the output current waveform of the induction generator 2 is distorted and good characteristics cannot be obtained, so that an expensive rotation detector is required.

Further, in the conventional configuration, the output current of the induction generator 2 has to be controlled by the instantaneous value of the alternating current, but there is a problem in the control method. In other words, the general control method is a method of FIG. 8 in which the AC current reference and the detected current are PI controlled, the output signal is converted into a pulse signal and distributed to each switch element. The current control circuit 104 has a PI control circuit for each phase. In this method, since the response speed of PI control is limited by the modulation frequency of PWM control, high-speed current control cannot be performed unless a very high-speed switching element is used. For this reason, it is necessary to provide a margin for the current rating of the switching element.

In the AC current control, an AC current reference and a detected current are compared by a hysteresis comparator, and PWM is directly output as an output of the hysteresis comparator.
There is also a method of obtaining a control signal. However, although this method allows higher-speed current control than the former, it has the disadvantage that the number of switching times increases and the loss increases. In any case, the conversion device is large and expensive.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has no need to consider the trouble of a rotation detector. It is also possible to reduce the size and cost, and to achieve high responsiveness and stability by high-speed current control. It is an object of the present invention to provide an induction generator control device capable of improving the power consumption.

[0012]

According to the present invention, there is provided a converter for converting an AC output of an induction generator driven by a prime mover into a DC, and a phase output current of each phase of the induction generator. And a current detector that outputs a current detection signal, and a PW for the converter based on a comparison between a current command signal and the current detection signal.
A control device for an induction generator that performs M control, wherein the current command signal and the current detection signal are input, and a current comparison circuit that outputs a logic level signal for each phase indicating a magnitude relation between the current command signal and the current detection signal; Based on the input, a voltage synchronization signal in which the logic level is inverted at each predetermined phase angle for each phase voltage of the induction generator, and a voltage basic phase signal for maintaining the commutation order of each phase in a predetermined order. A PWM control signal for the converter is output based on a commutation control signal circuit to be output, a voltage synchronization signal and a voltage basic phase signal from the commutation control circuit, and a logic level signal from the current comparison circuit. And a PWM control circuit.

[0013]

In the above configuration, the current comparison circuit compares the magnitude relationship between the current command signal and the current detection signal, compares the magnitude of the current change for each phase, and outputs the logical level signal for each phase. Output. As a result, the magnitude of the current change for each phase,
And the speed of the current change can be monitored.

Here, the output current waveform of the induction generator is generally determined by the magnetic flux, rotation speed, winding impedance, DC output voltage, load, etc. of the induction generator, but the present invention follows the change in rotation speed. In view of the fact that the output current waveform changes, the rotation detector is not required.

That is, when the induced electromotive force of the induction generator changes, the rate of change of the output current also changes. However, since the change of the induced electromotive force corresponds to the rotational speed, the change of the current change rate also changes. Corresponds to rotation speed.

The commutation control circuit outputs a voltage synchronizing signal by inputting a logic level signal indicating the change in the rate of change from the current comparing circuit. The commutation control circuit corresponds to the frequency rotation number of the voltage synchronizing signal. It will be.

This voltage synchronizing signal is also a logic level signal, and is used for inverting the logic level at a predetermined phase angle to capture commutation timing. However, if the voltage synchronization signals of each phase all have the same logical value at the same time, regular commutation cannot be performed. Therefore, the commutation control circuit also outputs a voltage basic phase signal for maintaining the commutation order in a predetermined order.

The PWM control circuit performs PWM control by inputting such a voltage synchronization signal, a voltage basic phase signal, and a logic level signal from the current comparison circuit.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of this embodiment.

In FIG. 1, reference numerals 1 to 12 are the same components as those of the conventional example shown in FIG. 13 is a command value of the peak value of the output current of the induction generator 2, 14 is a current comparison circuit, 15 is a current comparison signal, 16 is a commutation control circuit, 17 is a cycle measurement circuit, 18 is a delay circuit, and 19 is PWM. A control circuit, 20 is a frequency measurement circuit, and 21 is a function generator.

FIG. 2 is a block diagram showing a detailed configuration of the current comparison circuit 14 in FIG. In FIG. 2, reference numeral 13 denotes a command value of an output current peak value of the induction generator 2, IU, IV,
IW is the output current of the induction generator 2 detected by the current detector 8, 22 to 24 are polarity inverters, 25 to 30 are subtractors, 31 to 36 are hysteresis comparators, and the command value of the output current peak value and It compares the detected current with the detected current and outputs the result as power comparison signals UP, UN, VP, WP, WN. In FIG. 1, six current comparison signals are collectively indicated by reference numeral 15.

FIG. 3 is a block diagram showing details of the commutation control circuit 16 of FIG. In FIG. 3, 37 to 48 are AND circuits, 49 to 51 are flip-flops, 52 is a decoder, 53 is an OR circuit, 54 is an exclusive OR circuit,
55 is a NOT logic circuit, UF, VF and WF are voltage synchronizing signals obtained as outputs of 49 to 51, PH1 to PH6 are voltage basic phase signals obtained as outputs of the decoder 52, C
OM is a commutation synchronization signal, COMDL is a commutation permission control signal,
COMEN is a commutation permission signal.

FIG. 4 is a block diagram showing details of the PWM control circuit 17 of FIG. 4, 61 to 66 are NOT logic circuits, 68 to 79 are AND circuits, 80 to 82 are OR circuits, 83 to 85 are AND circuits, 86 to 88 are exclusive OR circuits, and PH1 to PH6 are outputs of the decoder 52. The signals UO, VO, and WO are the outputs of the exclusive OR circuits 68 to 88, respectively, and indicate the P level of each phase of the converter 3.
The WM signal and EPWM are PWM switching signals for switching between PWM control and 180-degree conduction.

According to the above device, the output current of the induction generator 2 is controlled in a trapezoidal waveform. The height of the trapezoidal wave is given by a peak value command value 13. In FIG. 2, each of the phase currents iU, iV, iW of the induction generator 2 or those obtained by inverting them by a polarity inverter -iU, -iV, -iW and the deviation from the peak value command value 13 are subtracters. The hysteresis comparators 31 to 36 operate according to the magnitude of the deviation. If the U-phase current iU is larger than the peak value command value, the output of the subtracter 25 becomes positive and the output UP of the hysteresis comparator 31 becomes "1". When the U-phase current iU becomes smaller than the peak value command value by a hysteresis or more, UP becomes “0”.

On the other hand, in the subtracter 26, when the magnitude of the signal obtained by inverting the polarity of the U-phase current iU exceeds the peak value command value, the output UN of the hysteresis comparator 32 becomes "1", and when the output UN becomes smaller than the peak value command value by hysteresis or more. UN is "0"
Becomes The same applies to the V phase and the W phase. That is, from the current comparison circuit of FIG. 2, it is determined whether the output current of the induction generator falls within the amplitude specified by the peak value command value.
It is output by the current comparison signal of WN.

The operation of the commutation control circuit shown in FIG. 3 will be described on the assumption that the output of the NOT logic circuit 55 is "1" for simplicity. The flip-flop 49 sets the current comparison signal UP to “1” when the voltage basic phase signal PH6 is “1”.
If the current comparison signal UN is "1" when the voltage basic phase signal PH3 is "1", it is set.

As will be described later, when the PWM is not operated in the PWM control circuit of FIG. 4, the output of the commutation control circuit 16 is output as it is as the output of the PWM control circuit. Switching control is performed by the output of 16.

Therefore, when the phase current iU is positive and becomes larger than the peak value command value, the switching element on the plus side of the U phase is turned off, the switching element on the minus side is turned on, and the voltage in the direction of decreasing iU is reduced. Is done. As a result, iU decreases from positive to negative, and when the absolute value of the negative value exceeds the peak value command value, the U-phase negative side switching element is turned off, and the positive side switching element is turned on to reset iU. The voltage is set to increase.

As described above, the flip-flop 49 is set / reset each time the phase current iU changes between positive and negative and its absolute value exceeds the peak value command value. The same applies to the V phase and the W phase. In this way, a voltage synchronizing signal of the converter is obtained as the outputs UF, VF, WF of the flip-flops 49 to 51.

If the input side of the converter is not an induction generator but a mere reactor, the change in current is determined by the reactor constant and the output voltage of the converter. The operating frequency of the converter is determined by the magnitude of the command value. On the other hand, when an induction generator is connected as in the present invention, an induced electromotive force is added in addition to the above.

When the magnetic flux of the induction generator is established, the current flows due to the difference between the output voltage of the converter and the induced electromotive force, so that the current change rate changes due to the change in the induced electromotive force. Looking at the change in induced electromotive force by phase, the rate of change is sinusoidal and the rate of change depends on the number of revolutions, so the higher the number of revolutions of the induction generator and the faster the change in induced electromotive force, the faster the current change rate, As the rotational speed decreases and the induced electromotive force changes slowly, the current change rate also changes. Thus, the frequency of the voltage synchronization signal automatically changes following the rotation speed of the induction generator, and the commutation of the converter can be controlled without a rotation detector.

Phase current i when PWM control is not performed
U and voltage synchronization signals UF, VF, WF and decoder 5
FIG. 5 shows the voltage basic phase signals PH1 to PH6 output by the power supply 2. The relationship between the input signal and the output signal of the decoder is, for example, as shown in the truth table of FIG.

Although the illustration of the phase currents iV and iW is omitted in FIG.
The signal is delayed by a degree. As mentioned earlier,
When the PWM control is not performed, the converter is controlled by the voltage synchronization signal to perform the 180-degree conduction control.
All of VF and WF must not be "1" or "0" at the same time. However, simply setting and resetting the flip-flop with the output of the hysteresis comparator can cause all to be "1" or "0" at the same time due to the effects of current ripple waveform, noise, current detection error, and logic circuit delay time. There is. Therefore, in FIG. 3, the decoder 52 and the AND circuits 43 to 48 prohibit all the phases from simultaneously becoming "1".

The output of the decoder 52 is PH1 as shown in FIG.
Only one of PH6 can take "1". When PH1 of the decoder output is "1", that is, at the input of the decoder, only VF is "1" and U
When F and WF are “0”, the flip-flop 5 is set so that PH2 of the decoder output becomes “1”, that is, WF becomes “1” at the decoder input.
Only the AND circuit 48 connected to one set input is enabled.

The flip-flops 49 to 51 are set so that only one of PH1 to PH6 becomes "1" in any state when the control power is turned on. I am trying to be. In addition to the initial state, 49-
Even when all of the 51 flip-flops are set to "1", the normal state can be restored by the next input signal change. The operation of the AND circuits 37 to 42 will be described later.

Next, the operation of the PWM control circuit shown in FIG. 4 will be described based on the operation waveforms shown in FIG. For simplicity, FIG. 6 shows the period during which the voltage basic phase signals PH1 to PH6 take "1" by their signal names.

In FIG. 6, the voltage basic electrical angle control signal UF
Is initially "1" and the current iU increases in the positive direction. At time t1, current iU reaches the peak value command value and current comparison signal U
P becomes "1". Commutation control circuit 1
At 6, the UF is set to "0". Due to the change in UF, PH1 of the decoder output becomes "1". Since the signals other than PH1 are "0", the output of only the AND circuit 77 among the AND circuits 74 to 79 in FIG. 4 changes depending on the state of the current comparison signal, and the outputs of the other AND circuits 74 to 76, 78 and 79 are the current comparison signal. It is "0" regardless of the state.

Therefore, the outputs of the OR circuits 80 and 82 become "0", and the outputs of the AND circuits 83 and 85 also become "0". Then, while PH1 is "1", the exclusive OR circuits 86 and 88 output the voltage basic electrical angle signals UF and WF as they are. During that time, the output of the exclusive OR circuit 87 is determined by the state of the current comparison signals UP and VN if the PWM / 180 degree conduction switching EPWM is "1".

After time t1, UP is "1", and the output of the AND circuit 71 is "0" because the signal passes through the NOT logic circuit 61. Therefore, the output of the OR circuit 81 also becomes “0”, and the exclusive OR circuit 87 outputs the voltage basic electrical angle signal VF as it is. As a result, the switching elements of the converter output voltage on the U-phase, the W-phase on the negative side, and the V-phase on the positive side are turned on, and the current iU starts to decrease.

When the current iU decreases and falls below the hysteresis level of the hysteresis comparator 31 at time t2, UP becomes "0". Since the current comparison signal VN has already been "0", the output of the AND circuit 71 becomes 1, and the output of the AND circuit 84 becomes "1" via the AND circuit 77 and the OR circuit 81. Therefore, the output VO of the exclusive OR circuit 87 is a signal obtained by inverting the frequency control signal VF, and the converter output voltage is U-phase, V-phase,
Both W phases are negative. That is, the line voltages are all zero, and the generator current flows by the induced electromotive force.

The instantaneous amplitudes of iU and iV start increasing, and t3
IV reaches the command value earlier than iU. As a result, VN becomes “1”, and the V-phase voltage changes from negative to positive similarly to the case where UP is “1”, and the current iV starts to decrease. Of course, the current iU also decreases. At t4, VN becomes "0", the line voltages of the generator are all set to "0", and both the currents iU and iV begin to increase due to the induced electromotive force. Thereafter, from t5 to t8, PWM control is performed by comparing the instantaneous value of iU.

At time t9, current iW reaches -i1 * and WN
Becomes “1”, the voltage basic electrical angle signal WF changes from “0” to “1”. As for the output of the decoder 52, PH2 is "1".
Becomes Thus, the outputs of the AND circuits 75 to 79 become "0" regardless of the current state, and only the output of the AND circuit 74 changes depending on the state of the currents iU and iw. At t9, the U-phase of the converter becomes negative, and the V-phase and W-phase become positive.

When iw decreases and WN becomes "0" at t10, the U-phase also becomes a positive voltage, and the line voltage becomes "0". iw
And the instantaneous amplitude of iU starts to increase, and UP becomes "1" at t11. As a result, the U-phase voltage is changed from positive to negative, iw and iU decrease, and UP becomes “0” at t12. In the same manner, PWM control is performed so that each phase current does not exceed the command value.

As described above, while PH1 is "1", the V-phase switch is turned on / off while watching the U-phase current state, whereby the U-phase current can be controlled to a predetermined peak value or less. . However, since the switching is performed in the V phase, if the switching control is performed only by the U phase current, the current of the V phase itself may exceed the peak value command value. For this reason. The AND circuit 71 ANDs the signal obtained by taking the negative logic of both UP and VN, and controls the current of the V phase itself so as not to exceed the peak value command value.

In the above, the output signal 15 of the current comparison circuit 14 is given to the commutation control circuit 16 and the PWM control circuit 19 in common, but the role of the output signal of the current comparison circuit 14 in these two circuits is quite small. Different. That is, the commutation control circuit 16 uses the commutation timing for controlling the commutation of the converter 3. In other words, the phase generator locks the phase of the induction generator to the power generation state by capturing the rising of the phase current and inverting the voltage of that phase, increasing the phase voltage to the phase current and setting the phase to a delay phase close to 180 degrees. On the other hand, in the PWM control circuit 19, the output signal of the current comparison circuit 14 is for controlling the maximum value of the current controlled by the PWM control. Also, the modulation frequency is determined by the magnitude of the hysteresis of the current comparison circuit 14. Therefore, a current comparison circuit for the commutation control circuit 16 and a current comparison circuit for the PWM control circuit 19 may be provided separately.

According to the apparatus shown in FIG. 1 having the current comparison circuit 14, the commutation control circuit 16, the PWM control circuit 16, and the PWM control circuit 19 as described above, the magnetic flux of the induction generator is established, When electric power is generated, the current of the generator can be controlled without a rotation sensor. The probability of the magnetic flux is determined by controlling the magnitude of the current reference output from the voltage control circuit 12 by the start-up control circuit 11.

When there is no induced electromotive force, the commutation control circuit 1
6, the rate of change of the generator is determined by the impedance of the winding of the generator 2 and the magnitude of the voltage of the DC power supply 5 for initial excitation. Therefore, the frequency is high if the current reference is small, and the frequency is high if the current reference is large. Lower. Therefore, when starting the converter, the current reference is reduced, the EPWM signal of the PWM control circuit is set to "0", the converter 3 is operated at a high frequency, and the current reference is gradually increased. As a result, the operating frequency of converter 3 gradually decreases.

When the operating frequency approaches the frequency corresponding to the rotation speed of the prime mover 1, the generator 2 starts operating as a generator,
An induced electromotive force is generated. Thereafter, when the current reference is increased, the generator current increases, and when the current reference is decreased, the generator current only decreases, and the frequency is determined by the frequency of the induced electromotive force. Whether the induction generator has started to operate as a generator can be determined by an increase in the DC voltage detected by the voltage detector 9. As a result, the PWM control is used by setting the EPWM signal to "1", and when the voltage required for the load 9 rises, the circuit breaker 6 is turned on to supply power to the load 9. Thereafter, the voltage control circuit 13 operates to increase or decrease the current reference depending on the level of the DC voltage, and control the DC voltage to a voltage required for the load 7.

The case where the current reference has a relatively large value has been described so far. If the current reference has a small value, inconvenience may occur. In FIG. 6, the current iU is t
At 13, the value changes from positive to negative, and at t 14, the minimum value due to the current ripple is taken, and the change direction changes in the positive direction. When the current iU is negative due to the ripple, the current reference is so small that the absolute value of the current iU exceeds the value of i1 *. When the commutation is performed, the voltage sequence of the induction generator 2 is out of order.

The interlock by the AND circuits 43 to 48 in FIG. 3 is to prevent this, and inhibits commutation other than the normal phase sequence. However, if the commutation by iV is performed only with this, the condition that the commutation by iU is performed immediately is satisfied, and the commutation cycle of the voltage synchronization signal becomes non-uniform. The interlock prevents this.

In FIG. 6, when the commutation by iV is performed at t15, the current iU once changes in the positive direction, and takes a positive value between t16 and t17. If the commutation by iU is also inhibited for a while after the commutation by iV at t15, the current iU changes in the positive direction during that time, and erroneous commutation due to current ripple can be prevented.

If this prohibition period is given for a certain period of time, when the rotation speed of the prime mover further decreases, the induced voltage changes gradually and the rate of change of the current increases, so that the prohibition period becomes insufficient. Therefore, the commutation prohibition period is given by an electrical angle.

In FIG. 6, the commutation prohibition period is set to an electrical angle of 30 degrees. The length of the prohibition period can be changed depending on the constant of the induction generator, the speed of change in the rotation speed of the induction generator, and the like. If the speed of change in the number of revolutions of the induction generator is extremely small, it may be slightly shorter than the electrical angle of 60 degrees. To set this commutation prohibition period, the commutation control circuit of FIG.
Out of the outputs of the OR circuit 53, PH1, PH3 and PH
5 and outputs the commutation synchronization signal COM.

As shown in FIG. 6, the commutation synchronization signal COM is a signal whose logical value is inverted every 60 electrical degrees. The cycle of the commutation synchronization signal COM is measured by the cycle measuring circuit 17 of FIG. The delay circuit 18 receives the commutation synchronization signal COM, delays the commutation synchronization signal COM only by the set input of the delay time, and outputs it. In FIG. 6, since the angle is 30 degrees, 1/2 of the cycle measured by the cycle measuring circuit 17 is set. A signal COMDL obtained by delaying the commutation synchronization signal COM by 30 degrees is output from the delay circuit 18 and supplied to the commutation control circuit 16.

In the commutation control circuit 16, a signal C obtained by taking exclusive OR of COM and COMDL in the exclusive OR circuit 54 and inverting the logic in the NOT logic circuit 55.
Output OMEN. As shown in FIG. 6, when commutation is performed every 60 electrical degrees, COMEN becomes logic “0” and prohibits the next commutation, and when a time equivalent to 30 electrical degrees has elapsed since commutation. Allow the next commutation. At this time, the current of the phase does not become larger than the reference separately from the phase to be originally commutated, such as immediately after commutation, so that a normal commutation operation can be performed.

The frequency measuring circuit 20 shown in FIG. 1 is used in place of the rotation detector of the motor 1. The frequency measurement circuit 20 outputs the commutation synchronization signal C output from the commutation control circuit 16.
The operation frequency of the converter is measured by counting OM. The function generator 21 inputs the operating frequency of the converter output from the frequency measurement circuit 20 and outputs a current-based limit value output from the voltage control circuit to the voltage control circuit 12.

That is, when the rotation speed of the prime mover 1 is high and the power generation capacity is large, the current reference output from the voltage control circuit 12 can be increased. When the rotation speed is low and the power generation capacity is small, the current reference is reduced. Can be Although the prime mover 1 may stop rotating when attempting to generate a large amount of power in spite of a low rotational speed, the power generation is stably continued by controlling the current-based limit value in this manner. be able to.

According to the apparatus shown in FIG. 1, the power generation can be controlled without the rotation detector, so that the generation stop due to the trouble of the rotation detector is eliminated. Further, since the closed loop of the rotation speed is eliminated from the power generation control, and the influence on the accuracy of the rotation speed detection and the control of the response speed is eliminated, high-speed and stable power generation control becomes possible. In addition, since the current control is performed at a high speed with little loss, it can be used up to the current rating of the switching element, and large power generation can be performed with a small converter. Furthermore, at low rotation speed where the current change is large,
Even in the case where the generated power is small, the loss of synchronization due to the current ripple hardly occurs, so that the operation range of the induction generator 2 can be expanded. Further, since the operating frequency of converter 3 can be detected and used as a substitute for the rotation speed signal, various controls can be performed in accordance with the rotation speed of prime mover 1.

[0059]

As described above, according to the present invention, since a rotation detector is not required, troubles caused by the rotation detector can be eliminated. Then, since there is no influence on the accuracy of the rotation speed detection and the control of the response speed, high-speed and stable control becomes possible.

For high-speed and low-loss current control,
The switching element can be used up to the limit of the current rating, and high power generation is possible with a small converter.

[Brief description of the drawings]

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

FIG. 2 is a block diagram showing a configuration of a current comparison circuit in FIG.

FIG. 3 is a block diagram showing a configuration of a commutation control circuit in FIG. 1;

FIG. 4 is a block diagram showing a configuration of a PWM control circuit in FIG. 1;

FIG. 5 is a waveform chart for explaining the operation of the commutation control circuit of FIG. 3;

FIG. 6 is a waveform chart for explaining the operation of the PWM control circuit of FIG. 4;

FIG. 7 is a truth table showing a relationship between an input and an output of the decoder of FIG. 3;

FIG. 8 is a block diagram showing a configuration of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 prime mover 2 induction generator 3 converter 8 current detector 14 current comparison circuit 16 commutation control circuit 19 PWM control circuit

Claims (1)

(57) [Claims] 1. A converter for converting an alternating current output of an induction generator driven by a prime mover into a direct current, and a current detector for detecting each phase output current of the induction generator and outputting a current detection signal. A control device for an induction generator that performs PWM control on the converter based on a comparison between a current command signal and the current detection signal, wherein the current command signal and the current detection signal are input, and A current comparison circuit that outputs a logic level signal for each phase; a voltage synchronization signal in which a logic level is inverted every predetermined phase angle for each phase voltage of the induction generator based on the input of the logic level signal; and A commutation control signal circuit for outputting a voltage basic phase signal for maintaining the phase commutation order in a predetermined order; a voltage synchronization signal and a voltage basic phase signal from the commutation control circuit; On the basis of the input logic level signal from the current comparator circuit, a control apparatus for an induction generator, characterized in that it includes a PWM control circuit for outputting a PWM control signal, the for the converter.