JPH10201248A - Power supply - Google Patents

Abstract

(57) [Problem] To provide a power supply device which operates at high speed by performing short-circuit control of a reactor based on an internal state corresponding to a load state or the like, and is excellent in stability and controllability. SOLUTION: A duty ratio of a pulse width modulation control signal of an inverter control means 14 for controlling an inverter circuit 7 is supplied to a power factor improvement control means 13, and a short-circuit start time and a short-circuit period of the short-circuit means are controlled based on the duty ratio. The short-circuit element 10 is driven by the short-circuit signal from the short-circuit start time to the short-circuit element 1 during the short-circuit period.
0, the reactor 2 and the second diode bridge 9
, The AC power supply 1 is short-circuited to improve the power supply power factor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device in which the power supply power factor is improved by short-circuiting the power supply through a reactor connected in series to the power supply, and more particularly to a power supply capable of operating at high speed and having excellent controllability. Related to the device.

[0002]

2. Description of the Related Art To extract more active power from a power supply, it is effective to improve the power factor of the power supply, and to increase the maximum capacity of the equipment by supplying a large amount of active power to the equipment of the load. be able to. In addition, by improving the power supply power factor, it is often possible to reduce the harmonic current of the power supply, which has recently become a problem, and it is possible to comply with domestic and foreign harmonic current regulations.

As a method for improving the power factor of a power supply device, there is a method disclosed in, for example, JP-A-7-7946. In this publication, a power supply is short-circuited through a reactor by a short-circuit element. Specifically, a short-circuit of a reactor is started according to a load state, a short-circuit current, a harmonic current content, a power supply power factor, a waveform distortion factor, and the like. Delay time and short circuit period.

[0004]

In the above-described conventional power factor improving method, the load state and the like are detected by the detecting means, and the delay time and the short-circuit time until the start of short-circuiting of the reactor are determined based on the detection result. Therefore, a delay occurs in the short-circuit signal due to the detection delay of the detection means, and the delay time until the start of the short-circuit and the short-circuit time become improper, and the responsiveness and stability are deteriorated. There is a problem that can not be.

[0005] Even if a short-circuit current, a harmonic current content, a power supply power factor, a waveform distortion factor, or the like is used instead of a load state, a delay similarly occurs, and responsiveness and stability deteriorate. There is a problem that control is not possible.

[0006] The present invention has been made in view of the above,
An object of the present invention is to provide a power supply device which operates at high speed by performing short-circuit control of a reactor based on an internal state corresponding to a load state or the like, and has excellent stability and controllability.

[0007]

In order to achieve the above object, the present invention is directed to a converter for converting AC power from an AC power supply into DC power, and controlling the DC power from the converter by pulse width modulation control. An inverter for converting to AC power, a reactor connected in series to the AC power supply,
And a short-circuit means for short-circuiting an AC power supply via the reactor, wherein a short-circuit start time and a short-circuit period of the short-circuit means are determined based on a duty ratio of a pulse width modulation control signal for controlling the inverter. The gist is to have a power factor control means for controlling the short circuit means to be driven during the short circuit period from the short circuit start time to improve the power factor.

According to the present invention, the short-circuit start time and short-circuit period of the short-circuit means are determined based on the duty ratio of the pulse width modulation control signal for controlling the inverter, and the short-circuit start time and the short-circuit period are determined from the short-circuit start time. During this period, since the power factor is improved by controlling the driving of the short-circuit means, it is possible to operate at high speed and stably without detection delay by the detection means or the like.

According to a second aspect of the present invention, there is provided a converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by performing pulse width modulation control, A power supply apparatus comprising: a reactor connected in series to a power supply; and a short-circuit means for short-circuiting an AC power supply via the reactor, wherein the short-circuit means controls the inverter based on an output frequency of a pulse width modulation control signal. The gist is to have a power factor control means for determining a short circuit start time and a short circuit period and controlling the short circuit means to be driven during the short circuit period from the short circuit start time to improve the power factor.

According to the present invention, the short-circuit start time and short-circuit period of the short-circuit means are determined based on the output frequency of the pulse width modulation control signal for controlling the inverter. During this period, since the power factor is improved by controlling the driving of the short-circuit means, it is possible to operate at high speed and stably without detection delay by the detection means or the like.

The present invention according to claim 3 further comprises a converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, A reactor connected in series to a power supply, and a power supply device having short-circuiting means for short-circuiting an AC power supply via the reactor, wherein the power supply device includes a pulse width modulation control signal that controls the inverter, based on a duty ratio and an output frequency. The gist is to have a power factor control means for determining a short circuit start time and a short circuit period of the short circuit means, and controlling the short circuit means to be driven during the short circuit period from the short circuit start time to improve the power factor. .

According to the third aspect of the present invention, a short-circuit start time and a short-circuit period of the short-circuit means are determined based on a duty ratio and an output frequency of a pulse width modulation control signal for controlling the inverter. Since the power factor is improved by controlling the drive of the short-circuit means during the short-circuit period from
The operation can be performed quickly and stably without detection delay by the detection means or the like.

According to a fourth aspect of the present invention, there is provided a converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, and a connection to the inverter. A power supply device comprising: a motor driven by the inverter; a reactor connected in series to the AC power supply; and short-circuit means for short-circuiting the AC power supply via the reactor. A short circuit start time and a short circuit period of the short circuit are determined based on the duty ratio of the control signal and the actual rotation speed of the electric motor, and the short circuit is controlled to be driven during the short circuit period from the short circuit start time. The point is to have a power factor control means for improving the power factor.

According to the present invention, the short-circuit start time and short-circuit period of the short-circuit means are determined based on the duty ratio of the pulse width modulation control signal for controlling the inverter and the actual rotation speed of the motor. During the period from the short-circuit start time to the short-circuit period, since the power factor is improved by controlling the driving of the short-circuit means, it is possible to operate at high speed and stably without detection delay by the detection means or the like.

According to a fifth aspect of the present invention, there is provided a converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by performing pulse width modulation control, and the inverter. And a power supply device having a motor connected to the inverter, a reactor connected in series to the AC power supply, and short-circuiting means for short-circuiting the AC power supply via the reactor. And determining a short-circuit start time and a short-circuit period of the short-circuit means based on the actual rotation speed,
The gist is to have a power factor control means for controlling the short circuit means to be driven during the short circuit period from the short circuit start time to improve the power factor.

According to the present invention, the short-circuit start time and the short-circuit period of the short-circuit means are determined based on the target rotational speed and the actual rotational speed of the electric motor. Since the power factor is improved by controlling the driving of the short-circuit means, the operation can be performed at high speed and stably without detection delay by the detection means or the like.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit diagram showing a configuration of a power supply device according to a first embodiment of the present invention. The power supply device shown in FIG. 1 includes a reactor 2 having one end connected to one output end of an AC power supply 1, and the other end of the reactor 2 is connected to a first diode bridge 3 including four diodes and a smoothing diode. It is composed of electrolytic capacitors 4, 5, and 6, and is connected to a converter that constitutes a voltage doubler rectifier circuit that rectifies an AC voltage from the AC power supply 1 to a DC voltage of a doubled voltage. The DC voltage from the converter is supplied to an inverter circuit 7 and converted into an AC voltage to drive the electric motor 8.

A second diode bridge 9 is connected to both ends of the AC power supply 1 via the reactor 2, and both output terminals of the second diode bridge 9 are composed of, for example, a bipolar transistor, an IGT, and a MOSFET. When the short-circuiting element 10 which is a switching element is connected and the short-circuiting element 10 is turned on, the reactor 2 and the second
The AC power supply 1 via the diode bridge 9 of
Thereby, the power factor of the power supply device can be improved.

The control terminal of the short-circuit element 10, that is, the base, is connected to a power-factor improvement control means 13 provided in a controller 11, and the short-circuit element 10 is driven by the power-factor improvement control means 13. 10 is turned on.

Further, zero-cross detection means 12 provided in the controller 11 is connected to both ends of the AC power supply 1 so that the zero-cross detection means 12 detects the time when the AC voltage of the AC power supply 1 passes through the zero cross point. The detection signal is supplied to the power factor improvement control means 13.

Further, the controller 11 has an inverter control means 14 in addition to the zero-cross detection means 12 and the power factor improvement control means 13.
Controls the inverter circuit 7 by pulse width modulation (PWM),
Thereby, the inverter circuit 7 is controlled so that the DC voltage from the converter is converted into the AC voltage. Further, a PWM signal for PWM-controlling the inverter circuit 7 from the inverter control means 14, specifically, a duty ratio signal of the PWM signal is also supplied to the power factor improvement control means 13.

FIG. 2 is a diagram showing signal waveforms at various parts of the power supply device shown in FIG. 1. In particular, the pulse width of the output signal of the power factor improvement control means 13 for driving the short-circuit element 10 and the driving of the inverter circuit 7 PWM from the inverter control means 14
The relationship with the signal duty ratio is shown. 2, reference numeral 21 denotes a voltage waveform of the AC power supply 1, 22 denotes a current waveform of the AC power supply 1 when the power factor is improved, and 23 denotes a short-circuit element 10.
A short-circuit signal 24, which is an output signal of the power factor improvement control means 13 for driving the PWM signal, indicates the duty ratio of the PWM signal of the inverter control means 14 converted into an analog value.

FIG. 3 is a functional diagram of a main part of FIG. 1 for explaining the operation principle of the power supply device shown in FIG. 1 in an easy-to-understand manner. As shown in FIG. 3, the inverter control means 14 calculates the duty ratio and the output frequency (modulation frequency) of the PWM signal for controlling the inverter circuit 7, and controls the inverter circuit 7 with the PWM signal calculated in this way. At the same time, the duty ratio of the PWM signal is supplied to the power factor improvement control means 13, and the power factor improvement control means 13 drives a short circuit 91 including the second diode bridge 9 and the short element 10 based on the duty ratio. Short circuit signal 2
3. Specifically, a short-circuit signal 23 defining a short-circuit start time and a short-circuit period is generated, and the short-circuit element 10 is driven by the short-circuit signal 23, whereby the AC power is supplied through the second diode bridge 9 and the reactor 2. In this embodiment, the duty ratio of the PWM signal for driving the inverter circuit 7 is obtained from the inverter control means 14 such that the power factor of the power supply device is improved by short-circuiting the short-circuit signal 1 and the short-circuit signal 23 is generated based on the duty ratio. It is generated.

Since the duty ratio of the PWM signal for driving the inverter circuit 7 is considered to be substantially equivalent to the instantaneous output power of the inverter circuit 7, a short-circuit signal is generated based on the duty ratio. By short-circuiting the AC power supply 1 via the power supply, the power factor can be improved in accordance with the operating state of the load of the power supply device.

The operation of the power supply device shown in FIG. 1 will be described in more detail. When a sine wave AC voltage as shown by a voltage waveform 21 in FIG. 2 is input from the AC power supply 1, a zero-cross point of this AC voltage is detected by the zero-cross detecting means 12 of the controller 11, Supplied. The power factor improvement control means 13 calculates a short-circuit start time and a short-circuit time from the zero cross point of the short-circuit signal 23 based on the duty ratio (24 in FIG. 2) of the PWM signal supplied from the inverter control means 14, and calculates the short-circuit time. The short-circuit signal 23 is output from the zero-cross point detected by the zero-cross detection means 12 by a short-circuit start time as shown by 23 in FIG. 2 to drive the short-circuit element 10 to the on state, thereby the second diode The AC power supply 1 is short-circuited via the bridge 9 and the reactor 2. After short-circuiting the AC power supply 1 during the short-circuit signal 23,
When the short-circuit element 10 is opened to the off state, the energy stored in the reactor 2 is released to the load side, rectified by the voltage doubler rectifier circuit including the first diode bridge 3 and the capacitors 4, 5, and 6, and Supplied to

By short-circuiting the AC power supply 1 via the reactor 2 in this way, the conduction time of the power supply current is extended as shown by the current waveform 22 in FIG. 2, and the power supply power factor is improved. In particular, in the present embodiment, the short-circuit signal is determined based on the duty ratio of the PWM signal for driving the inverter circuit 7, and since this duty ratio is substantially equivalent to the instantaneous output power of the inverter circuit 7, A short-circuit signal for power factor improvement corresponding to the operation state of the load is generated, and the power factor can be controlled at the best operating point. Conventionally, a load state detecting means such as a current sensor or a voltage detecting circuit has been provided. However, in the present embodiment, such a detecting means is not required. Hardware delay). Further, since the calculation of the short-circuit signal is not performed after detecting the change in the load state as in the related art, the power factor improvement control can be operated at high speed without delay, and the responsiveness and Controllability can be improved.

Actually, in FIG.
As the duty ratio 24 of the PWM signal increases as the duty ratio 24 increases, the short-circuit time of the short-circuit signal 23 from the power factor improvement control means 13 also increases, so that the load current and the output voltage Does not suddenly fluctuate or hunt or vibrate, and a stable operation can always be realized.

Next, an example of calculating the short-circuit start time and the short-circuit period of the short-circuit signal 23 will be described. The simplest calculation is a method using a linear function, and can be calculated as follows.

Short circuit start time =-(duty ratio-A) ×
B short circuit period = C × (duty ratio−D) Here, A, B, C, and D are constants determined by the system.

FIG. 4 is a diagram showing an example of the calculation result. The horizontal axis indicates the duty ratio, and the vertical axis indicates the elapsed time from the zero cross point. The hatched portion is a short-circuit period. The short-circuit start time is almost constant with respect to the duty ratio, but the short-circuit period increases as the duty ratio increases.

In this description, the short-circuit period is calculated using a linear function. However, actually, another function is used, or a value calculated in advance is stored in a data table, and the value is used by using the value. Is also good. Further, by changing the constants A, B, C, and D according to the range of the duty ratio, or by changing the calculation method, more excellent control can be performed.

Next, a second embodiment of the present invention will be described with reference to FIG. The power supply device shown in FIG. 5 is connected to both ends of an AC power supply 1 and has one end of a reactor 2 connected to one output terminal of a first diode bridge 3 for full-wave rectifying an AC voltage from the AC power supply 1; A short-circuit element 1 between the other end of the reactor 2 and the other end of the first diode bridge 3
0, whereby the AC power supply 1 is short-circuited by the short-circuiting element 10 via the reactor 2 and the first diode bridge 3, and the other end of the reactor 2 is connected via the diode 15 for preventing backflow. And is connected to the smoothing electrolytic capacitor 6 and the inverter circuit 7. The diode 15 prevents the smoothing electrolytic capacitor 6 from being short-circuited by the short-circuit element 10 when the short-circuit element 10 is turned on and the AC power supply 1 is short-circuited via the reactor 2 and the first diode bridge 3. .

In the power supply device shown in FIG. 5, similarly to the power supply device of FIG. The inverter circuit 7 is connected to the inverter control means 14 and connected to the rate improvement control means 13, and operates in the same manner as described with reference to FIG.

The power supply device shown in FIG. 5 basically applies the duty ratio of the PWM signal of the inverter control means 14 for controlling the inverter circuit 7 to the power factor improvement control means 13 in the same manner as the operation principle described with reference to FIG. Supply and power factor improvement control means 1
3 determines a short circuit start time and a short circuit period of a short circuit signal for driving the short circuit element 10 based on the duty ratio, and supplies the short circuit signal to the short circuit 91 to drive the short circuit element 10 to an on state. The AC power supply 1 is short-circuited via the reactor 2 and the first diode bridge 3 to improve the power supply power factor. In the circuit configuration shown in FIG. 5, the short circuit 91 shown in FIG. 3 includes the first diode bridge 3 and the short element 10.

More specifically, a zero-cross point of the AC voltage of the AC power supply 1 is detected by the zero-cross detecting means 12 of the controller 11, and the detection signal is supplied to the power-factor improvement control means 13. In addition, the power factor improvement control means 13
Inverter control means 1 for driving and controlling inverter circuit 7
The short-circuit start time and short-circuit period of the short-circuit signal are determined based on the duty ratio as shown by the short-circuit signal 23 in FIG. Control, whereby the AC power supply 1 is short-circuited via the reactor 2 and the first diode bridge 3. By short-circuiting the AC power supply 1 during the short-circuit signal 23 and then opening the short-circuit element 10 to the off state,
The energy stored in the reactor 2 is released to the load side,
The light is rectified by a rectifying / smoothing circuit including a diode 15 and a capacitor 6 and supplied to the inverter circuit 7.

By short-circuiting the AC power supply 1 via the reactor 2 as described above, the conduction time of the power supply current is extended as shown by the current waveform 22 in FIG. 2, and the power supply power factor is improved. In particular, the power supply device of the present embodiment determines the short-circuit signal based on the duty ratio of the PWM signal as in the embodiment of FIG. 1, and this duty ratio is substantially equivalent to the instantaneous output power of the inverter circuit 7. Therefore, a short-circuit signal for power factor improvement corresponding to the operation state of the load of the power supply device is generated, and the power supply power factor can be controlled at the best operating point.

Next, a third embodiment of the present invention will be described with reference to FIG. FIG. 6 shows only a basic configuration for explaining the operation principle of the third embodiment in an easy-to-understand manner. The specific circuit configuration is the power supply of any of the circuit configurations shown in FIGS. The present invention can be similarly implemented in an apparatus. Since the circuit configuration of the power supply device shown in FIGS. 1 and 5 has already been described in detail, only the basic operation of the third embodiment will be described with reference to FIG.

As shown in FIG. 6, the power supply of the third embodiment supplies the output frequency (modulation frequency) of the PWM signal of the inverter control means 14 for controlling the drive of the inverter circuit 7 to the power factor improvement control means 13. Accordingly, the power factor improvement control means 13 calculates the short-circuit start time and the short-circuit period of the short-circuit signal based only on the output frequency of the PWM signal, and supplies the calculated short-circuit signal to the short-circuit 91, whereby the AC power 1 is short-circuited to improve the power factor. The output frequency (modulation frequency) corresponds to, for example, the frequency of an AC power supply output from the inverter circuit when the load of the inverter circuit is an induction motor or the like. In the case of, this corresponds to the switching frequency of the energized phase.

As described above, even when the output frequency of the PWM signal from the inverter control means 14 is used instead of the duty ratio, the short-circuit start time and the short-circuit period of the short-circuit signal can be properly determined. Since the output frequency of the PWM signal has a strong correlation with the instantaneous output power of the inverter circuit 7, it is possible to always generate a short-circuit signal corresponding to the operation state of the power supply device and control the power supply power factor at the best operating point. It is. Conventionally, a load state detecting means such as a current sensor or a voltage detecting circuit is separately provided, but in the present embodiment,
Since such a detecting means is not required, there is no influence of the delay of the detecting means (hard delay such as a noise filter). In addition, since the calculation of the short-circuit signal is not performed after detecting the change in the load state as in the related art, the power factor improvement control can be operated at high speed without delay, and the responsiveness and Controllability can be improved.

A calculation sequence of the short-circuit start time and the short-circuit period of the short-circuit signal will be described. The simplest calculation is a method using a linear function, and can be calculated as follows.

Short-circuit start time =-(output frequency-A) × B Short-circuit period = C × (output frequency-D) Here, A, B, C, and D are constants determined by the system. In this calculation, the short-circuit period is calculated using a linear function. However, in practice, another function may be used, or a value calculated in advance may be stored in a data table, and the value may be used. Further, by changing the constants A, B, C, and D according to the range of the output frequency, or by changing the calculation method, more excellent control is possible.

Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG. 7 shows only a basic configuration for explaining the operation principle of the fourth embodiment in an easy-to-understand manner similarly to the case of FIG. 6, and the specific circuit configuration is shown in FIGS. The power supply device having any of the circuit configurations shown in FIG. Since the circuit configuration of the power supply device shown in FIGS. 1 and 5 has already been described in detail, only the basic operation of the fourth embodiment will be described with reference to FIG.

In the power supply device according to the fourth embodiment, as shown in FIG. 7, the inverter control means 14 for driving and controlling the inverter circuit 7 calculates the duty ratio and the output frequency of the PWM signal, and uses the calculated PWM signal. In addition to controlling the inverter circuit 7, the inverter control means 14
Both the duty ratio and the output frequency of the M signal are supplied to the power factor improvement control means 13. As a result, the power factor improvement control means 1
3 calculates the short-circuit start time and short-circuit period of the short-circuit signal based on the output frequency in addition to the duty ratio, and supplies the calculated short-circuit signal to the short-circuit circuit 91.
Are short-circuited to improve the power factor.

Since the duty ratio and output frequency of the PWM signal have a strong correlation with the instantaneous output power of the inverter circuit 7, a short-circuit signal corresponding to the operation state of the power supply is always generated, and the power supply power factor is adjusted to the best operating point. It is possible to control with. Further, unlike the conventional case, since the detecting means is not required, the apparatus can be operated at a high speed without being affected by the delay of the detecting means, without delaying the power factor improvement control, and having the responsiveness and control. Performance can be improved. It is also conceivable that the short-circuit signal is determined based on one of the variables of the duty ratio and the output frequency based on the first to third embodiments, and the correction is performed using the unused variable. .

FIG. 8 is a circuit diagram showing a configuration of a power supply device according to a fifth embodiment of the present invention. The power supply device shown in FIG. 3 is the same as the power supply device shown in FIG.
Is connected to the output of the motor 8 and the rotation speed of the motor 8 is detected by the rotation speed detection means 16 provided in the controller 11, and the detected rotation speed of the motor 8 is supplied to the power factor improvement control means 13; Thus, the power factor improvement control means 13 is configured to determine the short-circuit signal based on the duty ratio of the PWM signal from the inverter control means 14 and the rotation speed of the electric motor 8 from the rotation speed detection means 16. The other configuration and operation are the same as those of the power supply device of FIG. 1, and the same components are denoted by the same reference numerals.

FIG. 9 is a functional diagram of the main part of FIG. 8 for explaining the operation principle of the power supply device shown in FIG. 8 in an easily understandable manner. As shown in FIG. 9, the inverter control means 14 calculates the duty ratio and the output frequency of the PWM signal for driving the inverter circuit 7, controls the inverter circuit 7 with the calculated PWM signal, and calculates the calculated PWM signal.
The duty ratio of the signal is supplied to the power factor improvement control means 13. Further, the rotation speed of the electric motor 8 driven by the inverter circuit 7, that is, the actual rotation frequency is determined by the rotation speed detecting means 16.
The detected actual rotation frequency of the electric motor 8 is supplied to the power factor improvement control means 13.

As described above, the power factor improvement control means 13
When the duty ratio of the M signal and the actual rotation frequency of the electric motor 8 are supplied, a short-circuit signal is determined based on the duty ratio, and the short-circuit signal is corrected to improve the power factor based on the actual rotation frequency of the electric motor 8. For example, when the actual rotation frequency of the motor 8 is different from a steady value predicted in advance by the system, it is considered that the voltage of the AC power supply 1 fluctuates or the load torque of the motor 8 fluctuates. In this case, the duty ratio of the PWM signal output to the inverter circuit 7 is corrected, and the motor 8 is controlled so that the actual rotation frequency approaches the target rotation frequency. The short circuit start time and the short circuit period of the short circuit signal are corrected. In this manner, power factor improvement control with excellent controllability can be performed at high speed without being affected by fluctuations in the power supply voltage and fluctuations in the load torque.

Next, a sixth embodiment of the present invention will be described with reference to FIG. FIG. 10 shows only a basic configuration for easily explaining the operation principle of the sixth embodiment, and the specific circuit configuration is shown in FIG.
Can be implemented by the power supply device having the circuit configuration shown in FIG.
Since the circuit configuration of the power supply device shown in FIG. 8 has already been described in detail, only the basic operation of the sixth embodiment will be described with reference to FIG.

The power supply device according to the sixth embodiment supplies the target rotation frequency of the PWM signal of the inverter control means 14 for controlling the drive of the inverter circuit 7 to the power factor improvement control means 13 as shown in FIG. The actual rotation frequency, which is the actual rotation speed of the electric motor 8 detected by the rotation speed detection unit 16 shown in FIG. 8, is also supplied to the power factor improvement control unit 13, whereby the power factor improvement control unit 13 sets the target rotation frequency and the actual rotation speed. The short-circuit signal is determined based on the frequency. More specifically, the power factor improvement control means 13 determines a short-circuit signal based on the target rotation frequency, corrects the short-circuit signal for power factor improvement based on the actual rotation frequency of the electric motor 8, and corrects the corrected short-circuit signal. The AC power supply 1 is short-circuited by a short-circuit signal to improve the power supply power factor.

For example, if the actual rotation frequency of the motor 8 is different from a steady value predicted by the system, the voltage of the AC power supply 1 fluctuates or the load torque of the motor 8 fluctuates. In this case, the PWM output to the inverter circuit 7 is considered.
The motor 8 is controlled such that the actual rotation frequency approaches the target rotation frequency by correcting the duty ratio of the signal, and at the same time, the short-circuit start time and the short-circuit period of the short-circuit signal are corrected according to the actual rotation frequency of the motor 8. As a result, power factor improvement control with excellent controllability can be performed at high speed without being affected by the fluctuation of the power supply voltage or the fluctuation of the load torque.

In each of the above embodiments, a power supply device having the same power factor improving function and the same effect can be constituted even if the connection positions of the reactor, the short circuit, the capacitor and the like are exchanged. The present invention can be similarly applied to various power supply devices that have been replaced and changed as described above.

[0053]

As described above, according to the present invention, the short-circuit start time and short-circuit period of the short-circuit means are determined based on the duty ratio of the pulse width modulation control signal for controlling the inverter. During the period from the short-circuit start time to the short-circuit period, the power factor is improved by short-circuiting the AC power supply via the reactor by controlling the driving of the short-circuit means. High-speed and stable operation is possible at the point where the power supply power factor is the best.

According to the present invention, the short-circuit start time and short-circuit period of the short-circuit means are determined based on the output frequency of the pulse width modulation control signal for controlling the inverter. During the period, the AC power supply is short-circuited via the reactor to improve the power factor, so that there is no detection delay by the conventional detecting means and the like, and the power source operates at high speed and stably at the best point. be able to.

According to the third aspect of the present invention, the short-circuit start time and short-circuit period of the short-circuit means are determined based on the duty ratio and the output frequency of the pulse width modulation control signal for controlling the inverter. During the short-circuit period, the AC power supply is short-circuited via the reactor to improve the power factor.Therefore, there is no detection delay by the conventional detection means, etc., and the power supply power factor operates quickly and stably at the best point. can do.

According to the present invention, the short-circuit start time and the short-circuit period of the short-circuit means are determined based on the duty ratio of the pulse width modulation control signal for controlling the inverter and the actual rotational speed of the motor. During the short-circuit period from the start time, the AC power supply is short-circuited via the reactor to improve the power factor.Therefore, there is no detection delay by the conventional detection means, and the power supply power factor is fast and the best. It can operate stably.

According to the present invention, the short-circuit start time and the short-circuit period of the short-circuit means are determined based on the target rotational speed and the actual rotational speed of the electric motor. Since the power factor is improved by short-circuiting the AC power supply, there is no delay in detection by the conventional detecting means or the like, so that the power source can operate at high speed and stably at the best point.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a power supply device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing waveforms of signals of respective parts of the power supply device shown in FIG.

FIG. 3 is a functional diagram of a main part of FIG. 1 for explaining the operating principle of the power supply device shown in FIG. 1 in an easily understandable manner.

4 is a graph showing a short-circuit start time and a short-circuit period of a short-circuit signal calculated by a duty ratio in the power supply device shown in FIG. 1;

FIG. 5 is a circuit diagram showing a configuration of a power supply device according to a second embodiment of the present invention.

FIG. 6 is a diagram showing only a basic configuration for easily explaining the operation principle of the third embodiment of the present invention.

FIG. 7 is a diagram showing only a basic configuration for easily explaining the operation principle of a fourth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a configuration of a power supply device according to a fifth embodiment of the present invention.

FIG. 9 is a functional diagram of a main part of the diagram for explaining the operation principle of the power supply device shown in FIG. 8 in an easily understandable manner.

FIG. 10 is a diagram showing only a basic configuration for easily explaining an operation principle of a sixth embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 AC power supply 2 Reactor 3 First diode bridge 4, 5, 6 Capacitor 7 Inverter circuit 8 Motor 9 Second diode bridge 10 Short circuit element 11 Controller 12 Zero cross detection means 13 Power factor improvement control means 14 Inverter control means 16 Revolution Detection means

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[Procedure amendment]

[Submission date] December 5, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0045

[Correction method] Change

[Correction contents]

Since the duty ratio and the output frequency of the PWM signal have a strong correlation with the instantaneous output power of the inverter circuit 7, a short-circuit signal corresponding to the operation state of the power supply is always generated, and the power supply power factor is adjusted to the best operating point. It is possible to control with. Further, unlike the conventional case, since the detecting means is not required, the apparatus can be operated at a high speed without being affected by the delay of the detecting means, without delaying the power factor improvement control, and having the responsiveness and control. Performance can be improved. It is also conceivable that the short-circuit signal is determined based on one of the variables of the duty ratio and the output frequency based on the first to third embodiments, and the correction is performed using the variable that is not used. . For example, when a DC motor is connected to a load, an electromotive voltage is generated according to the rotation speed of the DC motor. When the load torque is light, the number of revolutions increases and the electromotive voltage increases, so that the power consumption decreases but the duty ratio increases. At this time, the short-circuit period is shorter than the short-circuit period determined only by the duty ratio. Further, when the load is heavy, the rotation speed becomes slow and the electromotive voltage becomes low, so that the power consumption increases but the duty ratio decreases. At this time, the short-circuit period is longer than the short-circuit period determined only by the duty ratio. Thus, for example,

## EQU1 ## Short circuit period = C × (duty ratio−D) −E ×
(Actual number of rotations-number of rotations N) C, D, and E are constants determined by the system. Rotational speed N: Rotational speed at the duty ratio at that time (set based on the V / F curve of the motor) By performing correction based on the rotational speed, it is possible to determine a short-circuit pulse suitable for power consumption. . This example is shown by a broken line in FIG. In this example, the correction is performed as a linear function. However, a method in which another function is used or the correction is performed based on a data table according to the characteristics of the motor may be considered.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Claims (5)

[Claims] A converter for converting AC power from the AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, a reactor connected in series to the AC power supply, And a short-circuit means for short-circuiting an AC power supply via the reactor, wherein a short-circuit start time and a short-circuit period of the short-circuit means are determined based on a duty ratio of a pulse width modulation control signal for controlling the inverter. And a power factor control means for controlling the short-circuit means to be driven during the short-circuit period from the short-circuit start time to improve the power factor. 2. A converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, a reactor connected in series to the AC power supply, And a short-circuit means for short-circuiting an AC power supply via the reactor, wherein a short-circuit start time and a short-circuit period of the short-circuit means are determined based on an output frequency of a pulse width modulation control signal for controlling the inverter. , During the short-circuit period from the short-circuit start time,
A power supply device comprising a power factor control unit that controls the short circuit unit to be driven to improve a power factor. 3. A converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, a reactor connected in series to the AC power supply, And a short-circuit means for short-circuiting an AC power supply via the reactor, wherein a short-circuit start time and a short-circuit period of the short-circuit means are based on a duty ratio and an output frequency of a pulse width modulation control signal for controlling the inverter. And a power factor control means for controlling the short-circuit means to be driven during the short-circuit period from the short-circuit start time to improve the power factor. 4. A converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, and connected to the inverter and driven by the inverter. A power supply device comprising: a motor, a reactor connected in series to the AC power supply, and short-circuit means for short-circuiting the AC power supply via the reactor, wherein a duty ratio of a pulse width modulation control signal for controlling the inverter and A power factor for determining a short-circuit start time and a short-circuit period of the short-circuit means based on the actual rotation speed of the motor, and controlling the short-circuit means to be driven during the short-circuit period from the short-circuit start time to improve a power factor. A power supply device having control means. 5. A converter for converting AC power from an AC power supply into DC power, an inverter for converting the DC power from the converter into AC power by pulse width modulation control, and connected to the inverter and driven by the inverter. And a short-circuiting means for short-circuiting the AC power supply via the reactor, wherein the short-circuit is performed based on a target rotation speed and an actual rotation speed of the motor. A power source control means for determining a short-circuit start time and a short-circuit period of the means, and controlling the driving of the short-circuit means to improve the power factor during the short-circuit period from the short-circuit start time. apparatus.