JP2000032776A - Power converting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a simple, low-cost power converting device that creates a current command value synchronized with an AC power supply voltage without detecting the AC power supply voltage. SOLUTION: This power converting device is provided with a hysteresis current controlling circuit 11 which inputs the deviation (e) between an AC current command value Isref and an AC current detected value Is to output a switching signal G0, a fundamental wave detecting filter 21 which removes the high harmonic constituent of the signal G0 to detect a fundamental wave constituent signal Vx, a coefficient circuit 22 which inputs the signal Vx to output a unit sine wave signal, and a multiplier 13 which multiplies the unit sine wave signal by a current amplitude command value Im* to output an AC current command value Isref.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control technology for a power converter such as a high power factor converter and a solar inverter.

[0002]

FIG. 23 shows, for example, Japanese Patent Publication No. 5-6455.
FIG. 1 is a block diagram showing a control circuit of a conventional power conversion device disclosed in Japanese Patent Publication No. 1 in the same format as the present invention,
In the figure, 1 is an AC power supply, 2 is a reactor, 3 is a power converter, 4 is a DC voltage source by a DC capacitor, 5 is a drive circuit for driving a switching element of the power converter 3, and 6 is an AC of the power converter 3. A current sensor 7 detects the current Is and a voltage sensor 7 detects the voltage value of the AC power supply 1.

[0005] Symbols in the tenth and subsequent numbers indicate constituent elements of the control circuit. Reference numeral 94 denotes a coefficient circuit of a gain K for obtaining a unit sine wave signal from an output signal of the voltage sensor 7, and reference numeral 13 denotes a unit obtained by the coefficient circuit 94. The sine wave signal is multiplied by an AC current amplitude command value Im ^* of the power converter 3 to perform the AC current command value I.
a multiplier 12 for outputting sref; a subtractor 12 for calculating a deviation e between the AC current command value Isref output from the multiplier 13 and the current Is detected by the current sensor 6;
Is a current control circuit that amplifies the deviation e output from the power converter 3 and outputs the AC voltage command value VAref of the power converter 3.

Reference numeral 92 denotes a carrier generation circuit, and reference numeral 91 denotes a comparator, which performs pulse width modulation. Carrier wave generation circuit 92
Outputs a triangular wave signal, and the comparator 91 compares the signal with an AC voltage command value VAref output from the current control circuit 93. Based on the comparison result signal G0, the drive circuit 5
, The switching element of the power converter 3 is driven.

Next, the operation will be described. Voltage sensor 7
By multiplying the power supply voltage Vs Vs = Vm · sinωt of the AC power supply 1 detected by (1) by K (= 1 / Vm) by the coefficient circuit 94, a unit sine wave signal sinωt synchronized with the power supply voltage Vs of the AC power supply 1 is obtained. The unit sine wave signal sinωt is input to the multiplier 13 and multiplied by the AC current amplitude command value Im ^* to obtain an AC current command value Isref Isref = Im ^* · sinωt synchronized with the power supply voltage Vs of the AC power supply 1. . In the subtractor 12, this AC current command value Isre
A deviation e e = Isref−Is between f and the AC current Is of the power converter 3 detected by the current sensor 6 is obtained. This deviation e is amplified by the current control circuit 93,
The AC voltage command value VAref of the power converter 3 is obtained.

The AC voltage command value VAref is supplied to a comparator 9
1, is compared with the triangular wave signal output from the carrier generation circuit 92, and based on the comparison result signal G 0, the components of the power converter 3 are turned ON and OFF, and the AC current Is is a power synchronized with the AC power supply 1. It follows the AC current command value Isref at a rate of 1.

[0007]

Since the conventional power converter is constructed as described above, in order to convert the command value of the AC current into a signal synchronized with the AC power supply, it is necessary to detect the AC power supply voltage. Since a voltage sensor is required, there is a problem in that space and cost are disadvantageous.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and provides a simple and inexpensive power converter that generates a current command value synchronized with an AC power supply voltage without detecting the AC power supply voltage. The purpose is to gain.

[0009]

The power converter according to the present invention is characterized in that the AC side is connected to an AC power supply via an impedance element, the DC side is connected to the DC power supply, and the switching element is turned on / off to control the power between AC and DC. A power converter that performs conversion, and a power converter that includes a current control circuit that outputs a switching signal that controls on / off of the switching element based on a deviation between an AC current command value and an AC current detection value. A hysteresis characteristic that outputs an on or off switching signal when the deviation is equal to or more than a predetermined + set value, and outputs an off or on switching signal when the deviation is equal to or less than the −set value; Based on a switching signal from the current control circuit, a voltage corresponding to the voltage of the AC power supply A unit sine wave generating unit that outputs a unit sine wave signal having a unit amplitude synchronized with the unit, and an AC current command generating unit that multiplies a current amplitude command value by the unit sine wave signal and outputs the AC current command value. It is a thing.

The unit sine wave generating means of the power converter according to the present invention includes a fundamental wave detection filter for receiving a switching signal from the current control circuit, removing a harmonic component thereof, and extracting a fundamental wave component signal, And a coefficient circuit having a predetermined gain and inputting the fundamental wave component signal and outputting a unit sine wave signal.

The unit sine wave generating means of the power converter according to the present invention includes a fundamental wave detection filter for inputting a switching signal from a current control circuit, removing a harmonic component thereof, and extracting a fundamental wave component signal, A zero cross detection circuit for detecting a zero cross of the fundamental wave component signal, and a sin generation circuit for generating a unit sine wave signal using an output from the zero cross detection circuit as a timing signal.

Further, in the power converter according to the present invention, after the power converter is started, it is inputted to the AC current command generator for a predetermined time until the unit sine wave signal from the unit sine wave generator is settled. A means for setting the current amplitude command value to 0 is provided.

Further, the power converter according to the present invention has a phase correcting means for correcting the phase of the unit sine wave signal by a phase difference between the voltage of the AC power supply and the AC voltage of the power converter based on the impedance element. It is provided.

Further, the phase correction means of the power converter according to the present invention is a phase shifter for shifting the unit sine wave signal by a predetermined phase.

Further, the power converter according to the present invention is such that the predetermined phase amount is changed according to the current amplitude command value.

Further, the phase correction means of the power converter according to the present invention comprises: an arithmetic circuit for outputting a signal corresponding to a voltage drop of an impedance element based on an AC current command value; and a fundamental wave component from a fundamental wave detection filter. And a subtracter for subtracting the output signal of the arithmetic circuit from the signal and outputting the result to the subsequent stage.

Further, the power converter according to the present invention is provided with voltage abnormality detecting means for detecting a voltage abnormality of the AC power supply based on the output of the fundamental wave detection filter.

Further, the voltage abnormality detecting means of the power converter according to the present invention rectifies the output of the fundamental wave detection filter and, when the amplitude value of the rectified output becomes less than a predetermined set value, a voltage drop abnormality of the AC power supply. It is determined.

Further, the voltage abnormality detecting means of the power converter according to the present invention, when the absolute value of the output of the fundamental wave detection filter exceeds a predetermined value, disconnects the connection between the AC power supply and the power converter. It is determined that the power failure in the open mode caused by the power failure.

Further, the power converter according to the present invention provides a connection between the AC power supply and the power converter when an absolute value of a deviation output between the AC current command value and the detected AC current exceeds a predetermined value. Is provided with voltage abnormality detection means for determining that the power failure in the open mode caused by the opening of the power supply.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. In FIG.
Reference numeral 3 denotes a power converter, which is constituted by a self-extinguishing type element which is a switching element such as a transistor capable of high-frequency switching or an IGBT.
1. A center tap circuit including transistors Q1, Q2 and diodes D1, D2. Each transistor performs a switching operation at a high frequency of about 10 to several hundred times the output frequency (for example, 60 Hz). Is converted into a rectangular high-frequency AC voltage including a sinusoidal fundamental wave. 1 is an AC power supply, 2 is a reactor as an impedance element, 5 is a drive circuit for driving a switching element of the power converter 3, and transistors Q1, Q
2, the gate signals G1 and G2 are transmitted. Reference numeral 6 denotes a current sensor for detecting the AC current Is of the power converter 3. As can be seen from FIG. 1, the present invention does not include a voltage sensor for detecting an AC power supply voltage.

Symbols in the tenth and subsequent numbers indicate components of the control circuit. Reference numeral 21 denotes a sine wave Vx synchronized with the AC power supply 1.
Is a coefficient circuit of a gain G for obtaining a unit sine wave signal from the output Vx of the fundamental wave detection filter 21, and 13 is an alternating current between the unit sine wave signal obtained from the coefficient circuit 22 and the power converter 3. A multiplier serving as an AC current command generating means for multiplying the current amplitude command value Im ^* to output an AC current command value Isref; 12, a current detected by the current sensor 6 and the AC current command value Isref output from the multiplier 13; This is a subtractor for calculating a deviation e from Is.

Numeral 11 denotes a hysteresis current control circuit for outputting a switching command G0 for the power converter 3 based on the deviation e output from the subtractor 12, and as shown in FIG. 3, predetermined + set value (+ h) and -set value By providing the hysteresis characteristic of (−h), the switching element of the power converter 3 operates such that the deviation e changes within the hysteresis width as shown in FIG. For example, when the deviation e is equal to or more than + h, G
0 becomes +1 and the gate signal G1 is 1 and G2 is 0 in order to increase the AC current Is. Therefore, the transistor Q1 is turned on and the transistor Q2 is turned off. When the deviation e is equal to or larger than -h, the gate signal G0 becomes -1, and the gate signal G1 is 0 and G2 is 1 in order to reduce the alternating current Is. Therefore, the transistor Q1 is turned off and Q2 is turned on.

Next, a method of creating the AC current command value Isref will be described. The power supply voltage Vs of the AC power supply 1 and the AC voltage VA of the power converter 3 have a relationship of a vector diagram shown in FIG. 5 for the fundamental wave when the AC current (detected value) Is is a sine wave current with a power factor of 1. . Here, the phase difference α is determined by the value of the reactor 2 and the alternating current Is. α = tan ⁻¹ ((ωL · Im) / Vm) Vs = Vm · sinωt Is = Im · sinωt

Here, when Vs is rated and ωL is 10%, the angle α is within 6 degrees. The amplitude is represented by the following equation. VAm = (Vm ² + (ωL · Im) ² ) ^0.5 VA fundamental wave component = VAm · sin ωt

Therefore, when Vs is rated and ωL is 10%, the fundamental wave component of VA is 100.5%. Therefore, when ωL is about 10% and Is is a sine wave current with a power factor of approximately 1, it is understood that the power supply voltage Vs and the VA fundamental wave component are almost the same.

Therefore, in the first embodiment, the power supply voltage Vs
Is detected, a VA fundamental component is extracted from the output G0 of the hysteresis current control circuit 11, and an AC current command value Isref is created based on the fundamental component. That is, assuming that the switching command output from the hysteresis current control circuit 11 is G0 and the voltage value of the DC voltage source 4 is VD, when the power converter 3 is a center tap type, the instantaneous value of VA is VA = G0 · (VD / 2). Therefore, the harmonic component generated by the pulse width modulation control from the switching command G0 is converted to the fundamental wave detection filter 2.
1 to extract the fundamental wave component Vx,
A unit sine wave signal of VA / Vm = VAm / Vm 正弦 sinωt ≒ sinωt is obtained via the coefficient circuit 22 of (= VD / 2 / Vm). FIG. 6 shows a switching command G0 output in the form of a rectangular wave and its fundamental wave component Vx.

As described above, since a unit sine wave signal synchronized with the AC power supply voltage Vs can be obtained from the output signal G0 of the hysteresis current control circuit 11, a voltage sensor for detecting the AC power supply voltage is provided. This is unnecessary, and the cost of the power converter can be reduced.

Embodiment 2 In the first embodiment, since the fundamental wave detection filter 21 removes a harmonic component generated by the pulse width modulation control, if the voltage of the AC power supply is distorted, the unit sine wave signal is distorted. . In the present embodiment, even if the voltage of the AC power supply is distorted,
The configuration of a control circuit that does not cause distortion in the AC current command value will be described.

Hereinafter, a second embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is that a fundamental wave of VA is detected from the output signal G0 of the hysteresis current control circuit 11 by the fundamental wave detection filter 31, and the detected fundamental wave is set to 0.
A zero cross signal is input to the cross detection circuit 32 every cycle to obtain a zero cross signal, and the counter 33 is reset by the zero cross signal, thereby synchronizing the count value of the counter 33 with the fundamental wave of VA, that is, the AC power supply. It is.

Next, the operation will be described. The switching command G0 of the power converter 3, which is the output of the hysteresis current control circuit 11, is input to the fundamental wave detection filter 31, and harmonic components other than the fundamental wave are removed. The signal Vx from which the harmonic components have been removed is input to the 0 cross detection circuit 32. As shown in FIG. 7, the 0 cross detection circuit 32 detects a 0 cross that changes from a negative value to a positive value, and outputs a pulse once per cycle. When this pulse is input to the counter 33, the count value of the counter 33 is reset to 0,
Counting up from 0 is performed. This count-up is performed at the frequency of the AC power supply 1 (typically 50 or 60 H
z) is performed by the fixed clock 34 obtained by dividing the frequency z).
By inputting the count value of the counter 33 as a phase signal to the sin generation circuit 35, a synchronized unit sine wave signal can be obtained even if the AC power supply 1 is distorted.

As described above, the counter 33 that operates in synchronization with the power supply voltage from the output signal G0 of the hysteresis current control circuit 11 is provided, and a unit sine wave signal synchronized with the AC power supply voltage is obtained from the count value. This eliminates the need for a voltage sensor to detect the AC power supply voltage, thus reducing the cost of the power converter and obtaining a unit sine wave signal synchronized with the power supply voltage even when the power supply voltage is distorted. Can be.

Embodiment 3 In the second embodiment, the counter is incremented by a fixed clock obtained by dividing the power supply frequency of 50 or 60 Hz. Therefore, when the power supply frequency fluctuates, a correct unit sine wave cannot be obtained. In the present embodiment, a description will be given of a configuration of a control circuit that makes the AC current command value have no distortion even when the frequency of the AC power supply fluctuates.

Hereinafter, a third embodiment of the present invention will be described with reference to FIG. The difference from the second embodiment is that the counter 33 in the second embodiment is replaced by a PLL (Phas
An eLocked Loop) circuit 36 is replaced.

Next, the operation will be described. The switching command G0 of the power converter 3, which is the output of the hysteresis current control circuit 11, is input to the fundamental wave detection filter 31, and harmonic components other than the fundamental wave are removed. The signal Vx from which the harmonic components have been removed is input to the 0 cross detection circuit 32. 0
The cross detection circuit 32 detects a 0 cross that changes from a negative value to a positive value, and outputs a pulse. PLL
The count is input to the circuit 36 to obtain a count value of the multiplied frequency synchronized with the input pulse. This count value corresponds to the phase of the input pulse frequency. By inputting the count value to the sin generation circuit 35, a synchronized unit sine wave can be obtained even if the AC power supply 1 is distorted or the frequency fluctuates. .

As described above, the PLL which operates in synchronization with the power supply voltage from the output signal of the hysteresis current control circuit 11
Since it has the circuit 36 and is configured to obtain a unit sine wave signal synchronized with the AC power supply voltage from the output thereof, a voltage sensor for detecting the AC power supply voltage is not required, and the cost of the power converter can be reduced. In addition, a unit sine wave signal synchronized with the power supply voltage can be obtained even when the power supply voltage is distorted or the frequency fluctuates.

Embodiment 4 FIG. In the first embodiment, the AC current command value Im ^* is directly multiplied by the unit sine wave to obtain the AC current command value Isref. However, as shown in FIG. 10, the amplitude command to the multiplier 13 is activated. Thereafter, the amplitude command is set to zero by the delay circuit 43a, the switch 41, and the constant unit 42 until the fundamental wave detection filter 21 responds, without being affected by the transient response of the fundamental wave detection filter 21. , Can be started stably.

FIG. 11 is a timing chart for explaining the above operation. That is, if the AC current amplitude command value Im ^* is started while the output of the fundamental wave detection filter 21 is not settled, a harmonic current flows through the reactor 2. On the other hand, when the configuration shown in FIG. 10 is employed, after the device is started, the switch 41 is switched to the constant unit 42 until a predetermined time ΔT set by the delay circuit 43a elapses.
From the AC current command value Isre
f is not output. After the elapse of the above-mentioned time ΔT when the output state of the fundamental wave detection filter 21 is settled, the switch 4
1 is switched to the Im ^* side, and the output of the multiplier 13, that is, the AC current command value Isref rises. Note that the predetermined time ΔT is usually several tens msec to several hundred msec.
Is sufficient, and by adopting the above configuration,
Substantial activation is not significantly delayed.

Embodiment 5 In the second embodiment, the AC current command value Im ^* and the unit sine wave signal are directly multiplied to obtain the AC current command value Isref. However, as shown in FIG. After the start, the fundamental wave detection filter 31 responds, the 0 cross detection circuit 32 detects the 0 cross pulse, and until the counter 33 is reset, the delay circuit 43b, the switch 41, and the constant unit 42 use the amplitude command. Is zero, it is possible to start up stably without being affected by the transient response of the fundamental wave detection filter 31 or the like. Note that the above operation is the same as in the fourth embodiment, and a detailed description thereof will be omitted.

Embodiment 6 FIG. In the third embodiment, the AC current command value Is ^* is directly multiplied by the unit sine wave signal to obtain the AC current command value Isref. However, as shown in FIG. After startup, the delay circuit 43c and the zero-crossing detection circuit 32 detect a zero-crossing pulse, and the PLL circuit 36 responds and outputs a multiplied frequency synchronized with the zero-crossing pulse. By setting the amplitude command to zero by the switch 41 and the constant unit 42, the operation can be stably started without being affected by the transient response of the fundamental wave detection filter 31, the response of the PLL circuit 36, and the like. Note that the above operation is the same as in the fourth embodiment, and a detailed description thereof will be omitted.

Embodiment 7 FIG. In the third embodiment, the unit sine wave signal is output to the output G of the hysteresis current control circuit 11.
0, the phase is the same as the AC voltage VA of the power converter 3. For example, the phase difference α from the power supply voltage Vs when the reactor 2 is 20% is 0 to 11
This is about a degree delay (see FIG. 5). Therefore, in the present embodiment, the configuration of a control circuit that corrects the phase when the phase difference is a problem will be described.

Hereinafter, a seventh embodiment of the present invention will be described with reference to FIG. The difference from the third embodiment is that the output signal Vx of the fundamental wave detection filter 31 is input to the 0 cross detection circuit 32 via the phase shifter 51.

Next, the operation will be described. The signal detected by the fundamental wave detection filter 31 is corrected by the phase shifter 51 to advance the phase. For example, if the reactor 2 is 20% and there is no correction according to the present embodiment, the delay is 0 degree under no load, but 11 degrees under rated load. Therefore, in applications where the load is used with a constant rated load, the reference sine wave signal can be made in phase with the power supply voltage by advancing the phase by 11 degrees by the phase shifter 51.

As described above, the phase shifter 51 corrects the signal Vx detected from the output signal G0 of the hysteresis current control circuit 11 through the fundamental wave detection filter 31 so that the phase is advanced, and then the PLL circuit 36 Is configured to obtain a unit sine wave signal synchronized with the AC power supply voltage, so that a voltage sensor for detecting the AC power supply voltage is not required, and the power conversion device can be reduced in cost. Even if it is distorted, even if the frequency fluctuates, a unit sine wave signal synchronized with the power supply voltage can be obtained,
Further, when the load is constant, the current command value can be in phase with the AC power supply voltage.

Embodiment 8 FIG. In the seventh embodiment, the phase correction of the unit sine wave signal is performed at a constant value regardless of the size of the load. In the present embodiment, the configuration of the control circuit that corrects the phase difference according to the load will be described. I do.

Hereinafter, an eighth embodiment of the present invention will be described with reference to FIG. The difference from the third embodiment is that the voltage signal V2 for the phase difference correction is subtracted from the output signal V1 of the fundamental wave detection filter 31 by the adder / subtractor 53, and the output V3 of the subtracter 53 is supplied to the zero cross detection circuit 32. It is the point that you are typing.

Next, the operation will be described. The voltage signal V2 for the phase difference correction, as shown in the vector diagram of FIG.
The voltage applied to the reactor 2 will be determined. Here, the voltage signal V2 for the phase difference correction is obtained from the differentiating circuit 52 which multiplies the AC current command value Isref by L · s (s is a Laplace operator). If the delay phase difference of the signal V2 is positive, the signal V3 corresponding to the power supply voltage is obtained by subtracting the signal V1 from the signal V1 by the adder / subtractor 53, so that the power supply voltage is always maintained even if the load changes. Is obtained.

As described above, the signal V1 detected from the output signal G0 of the hysteresis current control circuit 11 through the fundamental wave detection filter 31 is obtained by the AC current command value Isref and the phase correction signal V2 obtained from the differentiating circuit 52. Correct, PL
Since the unit circuit is configured to obtain a unit sine wave signal synchronized with the AC power supply voltage in the L circuit 36, a voltage sensor for detecting the AC power supply voltage is not required, and the power converter can be reduced in cost. Even if the power supply voltage is distorted or the frequency fluctuates, a unit sine wave signal synchronized with the power supply voltage can be obtained.In addition, even when the load fluctuates, the current command value always matches the AC power supply voltage. Can be in phase.

Embodiment 9 FIG. In the eighth embodiment, the phase correction of the unit sine wave signal is instantaneously performed by the differentiating circuit 52. However, in the present embodiment, when the responsiveness is not particularly required for the operation for improving the power factor, the differentiation is performed. A configuration of a control circuit that stably corrects a phase difference without using a circuit will be described.

Embodiment 9 of the present invention will be described below with reference to FIG. The difference from the third embodiment is that P
An adder / subtractor 54 subtracts a phase correction signal θ1 described later from the phase signal θ of the LL circuit 36, and outputs the output of the adder / subtractor 54 as si
This is the point of input to the n generation circuit 35.

Next, the operation will be described. The phase correction signal θ1 can be obtained from the following equation. θ1 = α = tan ⁻¹ ((ωL · Im) / Vm) When the AC power supply is constant, θ1 can be obtained from Im by setting Vm as a fixed value. The current amplitude command value Im ^* is input to the α operation circuit 55, and the above operation is performed to obtain θ1. The phase correction signal θ1 is subtracted from the phase signal θ of the PLL circuit 36 by the adder / subtractor 54, and the output of the adder / subtractor 54 is
By inputting the signal to the n generation circuit 35, a unit sine wave signal having the same phase as the power supply voltage is constantly obtained even when the load fluctuates.

As described above, a signal detected from the output signal G0 of the hysteresis current control circuit 11 through the fundamental wave detection filter 31 is converted into a phase signal θ by the PLL circuit 31,
Phase correction signal θ1 obtained from AC current amplitude command value Im ^*
This makes it possible to obtain a unit sine wave signal synchronized with the AC power supply voltage, so that a voltage sensor for detecting the AC power supply voltage is not required, and the power converter can be reduced in cost. Even if the power supply voltage is distorted or the frequency fluctuates, a unit sine wave signal synchronized with the power supply voltage can be obtained. It can always be in phase with the AC power supply voltage.

Embodiment 10 FIG. In the present embodiment, a configuration of a control circuit that can detect a voltage abnormality such as a voltage drop (power failure) without a voltage sensor will be described. Hereinafter, a tenth embodiment of the present invention will be described with reference to FIG. The difference from the first embodiment is that a rectifier circuit 61, an amplitude detection filter 62, and a comparator 63 are added.

Next, the operation will be described. The output Vx of the fundamental wave detection filter 21 uses that the phase and the amplitude are almost equal to the AC power supply voltage. That is, the rectifier circuit 6
The rectification is performed at 1, and the amplitude is obtained by an amplitude detection filter 62. When the amplitude is lower than a predetermined value, the comparator 63 determines that the voltage has dropped (power failure).

As described above, since the unit sine wave signal synchronized with the AC power supply voltage is obtained from the output signal G0 of the hysteresis current control circuit 11, the signal is synchronized with the power supply voltage without a voltage sensor for detecting the AC power supply voltage. In addition to being able to create a current command, a voltage drop of the AC power supply can be detected.

Embodiment 11 FIG. In the tenth embodiment, the power failure detection in the voltage drop mode is configured to be detected. However, in the present embodiment, the AC power supply and the power converter are connected to each other by opening a switch on the upper side of the device. Is configured to detect a power failure in the open mode caused by the connection being opened. Hereinafter, an eleventh embodiment of the present invention will be described with reference to FIG. When a power failure occurs in the open mode, the power converter 3 cannot supply current, so that the switching command does not change and a fixed switching pattern is output. Therefore, the output Vx is also the maximum positive or negative DC value, and is detected by inputting this to the window comparator 64. Note that the filter 65 is a delay filter for preventing a malfunction, and the voltage of the AC power supply is, for example,
In the case where voltage distortion due to commutation of the thyristor rectifier is included, this voltage distortion is transiently applied to the fundamental wave detection filter 21.
Is input to the comparator 64 through the circuit, and is prevented from being erroneously detected as a power failure even though the voltage is normal.

As described above, since the unit sine wave signal synchronized with the AC power supply voltage is obtained from the output signal G0 of the hysteresis current control circuit 11, the signal is synchronized with the power supply voltage without a voltage sensor for detecting the AC power supply voltage. In addition to being able to create a current command, a power failure in the open voltage mode of the AC power supply can be detected.

Embodiment 12 FIG. In the eleventh embodiment, the power failure in the open mode is detected from the output signal of the fundamental wave detection filter 21. However, in the present embodiment, the difference between the AC current command value and the AC current (detection value) is detected. The power failure in the open mode is detected from the deviation. Hereinafter, a twelfth embodiment of the present invention will be described with reference to FIG. If a power failure occurs in the open mode, the power converter 3 cannot supply current, and thus the deviation between the AC current command value and the AC current becomes greater than the hysteresis width. Accordingly, this deviation is detected by inputting it to the window type comparator 66. The operation value of the window comparator 66 is set to be equal to or larger than the hysteresis width. The filter 65 is a delay filter for preventing malfunction. Further, by detecting the current deviation, not only a power failure in the open mode, but also an abnormality of the switching element of the power converter 3, an abnormality of the drive circuit 5, and the like can be detected.

As described above, since the unit sine wave signal synchronized with the AC power supply voltage is obtained from the output signal G0 of the hysteresis current control circuit 11, the signal is synchronized with the power supply voltage without a voltage sensor for detecting the AC power supply voltage. In addition to being able to create the current command, it is also possible to detect a power failure in the open-circuit mode of the AC power supply and an abnormality of the switching element, the drive circuit, etc. of the power converter.

In the above description, the configuration of the power converter has been described using a single-phase center tap type circuit. However, the power converter can be applied to the single-phase full-bridge type circuit shown in FIG. By adopting this configuration, it can be applied to the three-phase full-bridge type circuit shown in FIG.

[0061]

As described above, the power converter according to the present invention has an AC side connected to an AC power supply via an impedance element and a DC side connected to a DC power supply, and controls on / off of a switching element. A power converter that performs power conversion; and a power converter that includes a current control circuit that outputs a switching signal that controls on / off of the switching element based on a deviation between an AC current command value and an AC current detection value. A hysteresis characteristic that outputs an on or off switching signal when the deviation is equal to or more than a predetermined + set value, and outputs an off or on switching signal when the deviation is equal to or less than the −set value. A voltage corresponding to the voltage of the AC power supply based on a switching signal from the current control circuit. A unit sine wave generating unit that outputs a unit sine wave signal having a unit amplitude synchronized with the unit, and an AC current command generating unit that multiplies a current amplitude command value by the unit sine wave signal and outputs the AC current command value. Therefore, the operation in synchronization with the voltage corresponding to the voltage of the AC power supply becomes possible without the need for the means for detecting the voltage of the AC power supply, and the apparatus becomes simple and inexpensive.

Further, the unit sine wave generating means of the power converter according to the present invention includes a fundamental wave detection filter for receiving a switching signal from the current control circuit, removing a harmonic component thereof, and extracting a fundamental wave component signal, Also, since a coefficient circuit having a predetermined gain and inputting the fundamental wave component signal and outputting a unit sine wave signal is provided, a unit sine wave signal can be obtained with a simple configuration.

The unit sine wave generating means of the power converter according to the present invention includes a fundamental wave detection filter for receiving a switching signal from the current control circuit, removing a harmonic component thereof, and extracting a fundamental component signal. Since there is provided a zero cross detection circuit for detecting zero crosses of the fundamental wave component signal and a sin generation circuit for generating a unit sine wave signal using an output from the zero cross detection circuit as a timing signal, the voltage of the AC power supply may be distorted. Even if there is a fluctuation in frequency or frequency, an accurate unit sine wave signal can be obtained.

Further, in the power converter according to the present invention, after the power converter is started, it is input to the AC current command generator for a predetermined time until the unit sine wave signal from the unit sine wave generator is settled. Since the means for setting the current amplitude command value to 0 is provided, the AC current command value rises in a stable form,
The stability of the control operation at the time of starting is improved.

Further, the power converter according to the present invention includes a phase correcting means for correcting the phase of the unit sine wave signal by a phase difference between the voltage of the AC power supply and the AC voltage of the power converter based on the impedance element. With this configuration, an AC current command value having the same phase as the voltage of the AC power supply can be created.

Further, since the phase correcting means of the power converter according to the present invention is a phase shifter for shifting the phase of the unit sine wave signal by a predetermined amount, the phase of the unit sine wave signal can be corrected with a simple configuration. Becomes

In the power converter according to the present invention, the predetermined phase amount is changed in accordance with the current amplitude command value. Therefore, regardless of the magnitude of the AC current, the voltage of the AC power supply is always changed. An in-phase AC current command value can be created.

Further, the phase correction means of the power conversion device according to the present invention includes an arithmetic circuit for outputting a signal corresponding to the voltage drop of the impedance element based on the AC current command value, and a fundamental wave component from the fundamental wave detection filter. A subtractor that subtracts the output signal of the arithmetic circuit from the signal and outputs it to the subsequent stage is provided, so that an AC current command value always in phase with the voltage of the AC power supply is generated regardless of the magnitude of the AC current. Can be.

Further, the power converter according to the present invention has the voltage abnormality detecting means for detecting the voltage abnormality of the AC power supply based on the output of the fundamental wave detection filter, so that the means for detecting the voltage of the AC power supply is required. Without this, it is possible to detect a voltage abnormality of the AC power supply, and the device becomes simple and inexpensive.

Further, the voltage abnormality detecting means of the power converter according to the present invention rectifies the output of the fundamental wave detection filter, and when the amplitude value of the rectified output falls below a predetermined set value, the voltage drop abnormality of the AC power supply. Therefore, a voltage drop abnormality of the AC power supply can be detected with a simple configuration.

Further, the voltage abnormality detecting means of the power converter according to the present invention disconnects the connection between the AC power supply and the power converter when the absolute value of the output of the fundamental wave detection filter exceeds a predetermined set value. Therefore, it is determined that the power failure in the open mode is caused by the power failure, so that the power failure in the open mode of the AC power supply can be detected with a simple configuration.

Further, the power converter according to the present invention provides a connection between the AC power supply and the power converter when an absolute value of a deviation output between the AC current command value and the detected AC current exceeds a predetermined set value. Is provided with voltage abnormality detection means for determining that the power failure in the open mode occurs due to the opening of the power supply, so that the power failure in the open mode of the AC power supply can be detected with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a power conversion device according to Embodiment 1 of the present invention.

FIG. 2 is a circuit diagram illustrating an example of a power converter used in the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a hysteresis current control circuit used in the first embodiment of the present invention.

FIG. 4 is an operation explanatory diagram of the hysteresis current control circuit used in the first embodiment of the present invention.

FIG. 5 is a vector diagram showing an operation of the power converter according to the first embodiment of the present invention.

FIG. 6 is a diagram showing an output waveform of the fundamental wave detection filter according to the first embodiment of the present invention.

FIG. 7 is a block diagram showing a power converter according to Embodiment 2 of the present invention.

FIG. 8 is an operation explanatory diagram of Embodiment 2 of the present invention.

FIG. 9 is a block diagram showing a power converter according to Embodiment 3 of the present invention.

FIG. 10 is a block diagram showing a power converter according to Embodiment 4 of the present invention.

FIG. 11 is an operation explanatory diagram of Embodiment 4 of the present invention.

FIG. 12 is a block diagram showing a power converter according to Embodiment 5 of the present invention.

FIG. 13 is a block diagram showing a power conversion device according to Embodiment 6 of the present invention.

FIG. 14 is a block diagram showing a power converter according to Embodiment 7 of the present invention.

FIG. 15 is a block diagram showing a power conversion device according to an eighth embodiment of the present invention.

FIG. 16 is a vector diagram showing an operation of the eighth embodiment of the present invention.

FIG. 17 is a block diagram showing a power conversion device according to Embodiment 9 of the present invention.

FIG. 18 is a block diagram showing a power conversion device according to Embodiment 10 of the present invention.

FIG. 19 is a block diagram showing a power conversion device according to Embodiment 11 of the present invention.

FIG. 20 is a block diagram showing a power conversion device according to a twelfth embodiment of the present invention.

FIG. 21 is a circuit diagram showing another example of the power converter used in the present invention.

FIG. 22 is a circuit diagram showing still another example of the power converter used in the present invention.

FIG. 23 is a block diagram illustrating a configuration of a conventional power converter.

[Description of Signs] 1 AC power supply, 2 reactor, 3 power converter, 4
DC voltage source, 6 current sensor, 11 hysteresis current control circuit, 12 subtractor, 13 multiplier, 21, 31
Fundamental wave detection filter, 22 coefficient circuit, 320 cross detection circuit, 33 counter, 35 sin generation circuit, 3
6 PLL circuit, 42 constant device, 43a, 43b, 43
c delay circuit, 51 phase shifter, 52 differentiator, 53,
54 adder / subtracter, 55 α operation circuit, 61 rectifier circuit,
62 amplitude detection filter, 63 comparator, 64, 65
Window type comparator.

Claims (12)

[Claims] An AC converter is connected to an AC power supply via an impedance element, and a DC converter is connected to a DC power supply via an impedance element to perform on / off control of a switching element to perform power conversion between AC and DC. In a power converter provided with a current control circuit that outputs a switching signal for turning on and off the switching element based on a deviation from an alternating current detection value, the current control circuit is turned on when the deviation becomes equal to or more than a predetermined + set value. Or an output of a switching signal from the current control circuit based on the switching signal from the current control circuit. Output a unit sine wave signal with a unit amplitude synchronized with the voltage corresponding to the Unit sine wave generating means, and the current power conversion apparatus amplitude command value and by multiplying the unit sine wave signal comprising the alternating current command generating means for outputting the alternating current command value. 2. The unit sine wave generating means has a fundamental wave detection filter for inputting a switching signal from a current control circuit, removing a harmonic component thereof and extracting a fundamental wave component signal, and a predetermined gain. 2. The power conversion device according to claim 1, further comprising a coefficient circuit that inputs a fundamental wave component signal and outputs a unit sine wave signal. 3. A unit sine wave generating means for inputting a switching signal from a current control circuit, removing a harmonic component thereof, and extracting a fundamental wave component signal, a zero crossing of the fundamental wave component signal. 2. The power conversion device according to claim 1, further comprising: a zero cross detection circuit for detecting a signal; and a sin generation circuit for generating a unit sine wave signal using an output from the zero cross detection circuit as a timing signal. 4. A predetermined time from the start of the power converter until the unit sine wave signal from the unit sine wave generating means settles,
The power converter according to any one of claims 1 to 3, further comprising means for setting a current amplitude command value input to the AC current command generating means to zero. 5. A phase correction means for correcting the phase of a unit sine wave signal by a phase difference between a voltage of an AC power supply and a voltage of an AC side of a power converter based on an impedance element. 5. The power converter according to any one of claims 4 to 4. 6. A phase shifter for shifting a unit sine wave signal by a predetermined phase amount.
The power converter according to any one of the preceding claims. 7. The power converter according to claim 6, wherein the predetermined phase amount is changed according to the current amplitude command value. 8. An arithmetic circuit for outputting a signal corresponding to a voltage drop of an impedance element based on an AC current command value, and an output signal of the arithmetic circuit from a fundamental wave component signal from a fundamental wave detection filter. 6. The power conversion device according to claim 5, further comprising a subtractor for subtracting the value from the output and outputting the result to a subsequent stage. 9. The power converter according to claim 1, further comprising voltage abnormality detection means for detecting a voltage abnormality of the AC power supply based on an output of the fundamental wave detection filter. 10. An abnormal voltage detecting means for rectifying an output of a fundamental wave detecting filter, and judging that the voltage drop of the AC power supply is abnormal when an amplitude value of the rectified output is less than a predetermined set value. The power converter according to claim 9, characterized in that: 11. An open-circuit power failure caused by an open connection between an AC power supply and a power converter when an absolute value of an output of a fundamental wave detection filter exceeds a predetermined set value. The power converter according to claim 9, wherein the determination is made. 12. An open mode power failure caused by the disconnection of the connection between the AC power supply and the power converter when the absolute value of the deviation output between the AC current command value and the AC current detection value exceeds a predetermined set value. The power conversion device according to any one of claims 1 to 8, further comprising a voltage abnormality detection unit that determines that the voltage is abnormal.