JPH0739164A - Correcting apparatus for distortion of output voltage waveform of inverter - Google Patents

Abstract

PURPOSE:To eliminate the waveform distortion of a voltage at the receiving end of a nonlinear load without being influenced by an impedance element and to obtain sine waves in an apparatus which supplies electric power to the nonlinear load via the impedance element such as an interconnection, a transformer or the like from a power supply device provided with an inverter which converts DC electric power into AC electric power. CONSTITUTION:An output current on the side of a power supply device X is detected by a current transformer 21 and an outputcurrent detector 22. An impedance Z such as an interconnection, a transformer or the like in an electric passage which connects the output end of the power supply device X to the receiving end of a nonlinear load 4 is set in an impedance setting device 23. When the product of the output current of the detector 22 multiplied by the set impedance of the setting device 23 is found by a voltage-drop-amount detection circuit 24, a waveform distortion amount at the receiving end of the nonlinear load 4 with reference to the output voltage waveform of the power supply device X can be obtained. On the basis of the obtained waveform distortion amount, an inverter 2 is controlled, and a waveform distortion is corrected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an uninterruptible power supply (UP).
S) or a frequency converter (CVCF) or other power supply device, and more particularly to an inverter output voltage waveform distortion correction device.

[0002]

2. Description of the Related Art When a non-linear load such as a rectifying load is connected to a power supply device such as UPS or CVCF, the current flows
The internal impedance of the power supply device causes waveform distortion such as a decrease in the peak value of the voltage. Therefore, depending on the load, malfunctions and other effects may occur. In order to solve this problem, conventionally, as shown in FIG. 3, for example, a circuit has been employed in which waveform distortion is detected from the output of the power supply device, the waveform distortion is corrected in inverter control, and the output voltage waveform is a sine wave. It was

In FIG. 3, reference numeral 1 is a DC power supply, and 2 is an inverter for converting the DC power of the DC power supply 1 into an AC power. The AC output power of the inverter 2 is transformed by the transformer 3 and then supplied to the non-linear load 4. Reference numeral 5 is a capacitor for an AC filter. Reference numeral 6 is a waveform distortion detection circuit for detecting the waveform distortion of the output voltage of the power supply device X. This waveform distortion detection circuit 6
The detection output of is compared with the set value of the distortion correction setting device 8 in the matching circuit 7.

Reference numeral 9 is a waveform distortion correction circuit for producing a waveform distortion correction signal based on the deviation output of the matching circuit 7, and the output thereof is matched with the sine wave signal of the sine wave oscillator 11 in the matching circuit 10. Reference numeral 12 is an inverter control circuit for controlling the inverter 2 based on the deviation output of the matching circuit 10 and making the output voltage waveform a sine wave.

[0005]

According to the above circuit,
When impedance is present between the power supply device X and the power receiving end of the non-linear load 4 such as when the power supply device X is installed apart from the non-linear load 4, and further when connected through a transformer, the non-linear The voltage at the receiving end of the load 4 does not become a sine wave.

That is, even if the output voltage is a sine wave at the output end of the power supply device X, there is impedance between the power supply device X and the power receiving end of the non-linear load 4, so that the non-linear load 4
The voltage waveform is distorted at the power receiving end. This may cause malfunction of the load device.

The present invention has been made in view of the above points, and an object thereof is to make an inverter capable of converting the voltage at the receiving end of the non-linear load to a sine wave even when the non-linear load is separated from the power supply device. An object is to provide an output voltage waveform distortion correction device.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a device for supplying power to a non-linear load from an electric power supply device having an inverter for converting DC power into AC power, through an impedance element such as wiring or a transformer. (1) A waveform distortion correction unit that detects a waveform distortion of the output voltage of the inverter based on the voltage at the power receiving end of the nonlinear load and creates a correction signal that corrects the detected waveform distortion, The output voltage waveform of the inverter is controlled to be a sine wave based on the correction signal created by the correction unit, (2) the output current detection value at the output end of the power supply device and the impedance of the impedance element And a correction signal for correcting the waveform distortion calculated by the voltage decrease amount detection unit, which calculates the amount of waveform distortion at the power receiving end of the nonlinear load by the product of A waveform distortion correction unit that creates,
The output voltage waveform of the inverter is controlled to be a sine wave based on the correction signal generated by the waveform distortion correction unit.

[0009]

(1) In the invention of claim 1, since the waveform distortion is detected at the power receiving end of the non-linear load, the power receiving device is not affected by the impedance of the electric path connecting the non-linear load with any value. The voltage waveform at is a sine wave.

(2) In the invention of claim 2, the voltage drop amount detecting unit detects the current not at the power receiving end side of the non-linear load but at the output end of the power supply device. Since the product of the impedance and the impedance of the electric path connecting the loads is obtained, the amount of waveform distortion at the power receiving end of the nonlinear load can be obtained. Therefore, the voltage waveform at the power receiving end of the non-linear load becomes a sine wave regardless of the impedance of the electric path connecting the power supply device and the non-linear load.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the invention described in claim 1 will be described below with reference to the drawings. 1, the same parts as those in FIG. 3 are indicated by the same reference numerals. 1 is different from FIG. 3 in that waveform distortion detection is performed at the power receiving end of the non-linear load 4, and other parts are configured the same as in FIG. Incidentally, Z represents the impedance of the wiring of the electric path connecting the output end of the power supply device X and the power receiving end of the nonlinear load 4, the transformer, and the like.

According to the above circuit configuration, since the inverter 2 is controlled by the waveform distortion correction signal created based on the detected voltage at the power receiving end of the non-linear load 4, the voltage waveform at the power receiving end is converted into a sine wave. can do.

Next, an embodiment of the invention described in claim 2 will be described. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. 2 is different from FIG. 1 in that the secondary current of the transformer 3 on the power supply device X side is detected by the output current detector 22 via the current transformer 21, and is set by the detected current and the impedance setting device 23. Is obtained by the voltage drop amount detection circuit 24, and the output of the voltage drop amount detection circuit 24 is input to the waveform distortion detection circuit 6, and the other parts. Are configured the same as in FIG.

The set value of the impedance setter 23 is set to a measured value of the impedance Z from the power supply device X to the power receiving end of the non-linear load 4 or determined by assumption when the measurement is difficult. This impedance Z is constant because it is the reactor component and the resistance component. The product (that is, the voltage) of the impedance Z and the output current detector 22 is the amount of waveform distortion at the power receiving end of the nonlinear load 4 with respect to the output voltage waveform of the power supply device X.

Therefore, the waveform distortion amount thus obtained by the voltage drop amount detecting circuit 24 is regarded as the waveform distortion amount at the power receiving end of the non-linear load 4, and the waveform distortion correction is performed by the inverter control as described above. Therefore, the output voltage waveform at the output end of the power supply device X includes correction of the waveform distortion due to the impedance Z of the electric path between the power supply device X and the nonlinear load 4, and the voltage waveform at the power reception end of the nonlinear load 4 is sinusoidal. Become a wave.

[0016]

As described above, according to the present invention, the waveform distortion is detected at the power receiving end of the non-linear load to correct the distortion, and the impedance of the electric path connecting the power supply device and the power receiving end of the non-linear load and the power supply device. Since it is configured to calculate the amount of waveform distortion by the product of the output current on the side and correct the distortion, it is possible to make the voltage waveform a sine wave at the power receiving end of the non-linear load, and to prevent malfunction of load side equipment. Can be prevented.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the invention described in claim 1.

FIG. 2 is a circuit diagram showing an embodiment of the invention described in claim 2.

FIG. 3 is a circuit diagram showing an example of a conventional inverter output voltage waveform distortion correction circuit.

[Explanation of symbols]

 1 ... DC power supply 2 ... Inverter 3 ... Transformer 4 ... Nonlinear load 5 ... Filter capacitor 6 ... Waveform distortion detection circuit 7, 10 ... Matching circuit 8 ... Distortion correction setting device 9 ... Waveform distortion correction circuit 11 ... Sine wave oscillator 12 ... Inverter control unit 21 ... Current transformer 22 ... Output current detector 23 ... Impedance setting device 24 ... Voltage drop detection circuit X ... Power supply device Z ... Impedance of wiring, transformer, etc.

Claims (2)

[Claims] 1. A device for supplying electric power to a non-linear load through an impedance element such as wiring and a transformer from a power supply device having an inverter for converting direct-current power into alternating-current power, wherein the voltage at the receiving end of the non-linear load. The waveform distortion of the output voltage of the inverter is detected based on, and a waveform distortion correction unit that creates a correction signal that corrects the detected waveform distortion is provided, and based on the correction signal created by the waveform distortion correction unit. An inverter output voltage waveform distortion correction device, wherein the output voltage waveform of the inverter is controlled to be a sine wave. 2. A device for supplying electric power to a non-linear load through an impedance element such as wiring or a transformer from a power supply device having an inverter for converting DC power into AC power, wherein an output current at the output end of the power supply device. A voltage drop amount detection unit that obtains the amount of waveform distortion at the power receiving end of a non-linear load by the product of the detected value and the impedance of the impedance element, and a waveform that creates a correction signal that corrects the waveform distortion found by the voltage drop amount detection unit An inverter output voltage waveform distortion correction device, comprising: a distortion correction unit, and controlling the output voltage waveform of the inverter to be a sine wave based on the correction signal created by the waveform distortion correction unit.