JPH05181549A - Phase difference detecting method - Google Patents

Abstract

PURPOSE:To obtain a phase difference detecting method for various power units which are put in operation synchronously with a commercial power source. CONSTITUTION:This method has means 6 and 7 which detect a commercial source voltage 1 and the output voltage of the power unit in synchronous operation, a means which compares the two detected voltages by a phase comparator 8 and detects their phase difference, and an arithmetic means which corrects the detected value on the basis of a rated frequency. Further, the method is provided with a means which calculates the algebraic sum of the previously set deviation reference quantity of a phase and the corrected detected value of the phase comparator and a means which feeds the arithmetic output back to the control circuit 3 of the power source as a high frequency signal via a VCO4 after PI control 11. Consequently, variation in the output voltage frequency of the power unit is corrected to detect an accurate phase difference.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase difference detecting method in various power supply devices that operate in parallel with a commercial power supply.

[0002]

2. Description of the Related Art In order to synchronously control a power supply device that operates in parallel with a commercial power supply, the circuit shown in FIG. 3 detects a phase difference and controls the phase difference amount as a deviation input. FIG. 3 is a block circuit diagram showing a conventional phase difference detection method, in which the voltage V _C of the commercial power source 101 and the output voltage V _B of the main circuit 102 of the power source device 100 that operates in synchronization with the commercial power source 101 are Voltage detection circuits 106 and 10
7 and the phase difference is detected by being input to the phase comparator 108. The algebraic sum of the output of the phase comparator 108 and the phase deviation reference amount ψ ^* is calculated at a summing point 110, and a VCO (Voltage Control) is obtained.
It is converted into a high frequency signal via a led oscillator 104 and fed back to the control circuit 103 of the power supply device 110. The operation output of the summing point 110 is a proportional element K _P and an integral element K _S / (first-order lag). 1 + T
Controlled by the PI control method consisting of S).
The switching circuit 105 is provided for the power switching operation between the commercial power source 101, the load and the power supply device 110, and the switching operation is performed after the phase of the voltage V _{C and} the phase of the voltage V _B are synchronized. .

[0003]

In order to control the output voltage V _B of the power supply device 100 to follow the voltage V _C of the commercial power supply 101 synchronously, the power supply device 1 should have a phase difference of 0.
It is necessary to control the control circuit 103 of 00. 2A and 2B are timing charts of frequency waveforms of the commercial power supply voltage and the output voltage of the power supply device, both of which are V _B
2 is ahead of the phase of V _C in FIG.
2A shows the case where the frequency of V _B is f ₀₀ , and FIG.
Indicates the case where the frequency of V _B is f ₀₁ . Figure 2 (a)
The phase difference between V _B and V _C in (b) and (b) can be expressed by the following equations based on the frequency of V _B. Δψ ₀ = ΔT ₀ · f ₀₀ · 2π (rad) Δψ ₁ = ΔT ₁ · f ₀₁ · 2π (rad) The output detected by the phase comparator 108 is ΔT ₀ when the frequency of V _B is f ₀₀ . , F ₀₁ , ΔT ₁ . Therefore, even if ΔT ₀ = ΔT ₁ , since Δψ ₀ and Δψ ₁ do not become equal as is clear from the equations 1 and 2, the detection output ΔT from the phase comparison circuit 108 is accurately used as it is as the deviation input of the control system. It does not control the phase difference. The present invention has been made in order to eliminate the above-mentioned drawbacks in the conventional technique, and corrects the output of the phase comparator with the rated frequency as a reference, and controls the accurate phase difference amount as a deviation input. It is intended to provide a method.

[0004]

In order to achieve the above-mentioned object, a phase difference detecting method according to the present invention comprises means for detecting an output voltage and a commercial power supply voltage of a power supply device which operates in parallel with a commercial power supply, A means for comparing the two detection voltages in a phase comparator to detect the phase difference between them, a multiplication means for correcting the detection output based on the rated frequency according to the output frequency of the power supply device, and a preset phase Means for calculating the algebraic sum of the deviation reference amount of P and the detected value of the phase comparator corrected by the multiplying means, and the calculated output as PI.
It is constituted by means for controlling and feeding back as a high frequency signal via the VCO.

[0005]

The detected output ΔT of the phase comparator is corrected by a multiplier of (f ₁ / f ₀ ) times with the rated frequency f _{0 of the} power supply device and the commercial power supply frequency f ₁ . By this means, the fluctuation of the output frequency of the power supply device is adjusted, and the accurate phase difference amount is controlled as the deviation input.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a phase difference detecting method according to the present invention will be described below with reference to the drawings.

FIG. 1 is a block circuit diagram showing an embodiment of a phase difference detecting method. In FIG. 1, a commercial power supply 1 and a main circuit 2 of a power supply device that operates in synchronization with the commercial power supply 1 are connected to a load via a switching circuit 5. The output voltage V _B of the main circuit 2 of the power supply device and the commercial power supply voltage V _C are the voltage detection circuits 6 and 7, respectively.
Is converted into a voltage, and the phase difference Δφ is detected by the phase comparator 8. This detected value is multiplied by (f ₁ / f ₀ ) times in the multiplier 9, and the algebraic sum of the deviation reference amount ψ ^* of the preset phase and the multiplied operation output is calculated at the addition point 10. . That is, the detected value of the phase comparator 8 is corrected with the rated frequency as a reference, and the accurate phase difference amount can be controlled with the deviation input.

The operation output at the summing point 10 is PI
It is input to the VCO 4 via the control system 11, converted into a high frequency signal, and then fed back to the control circuit 3 of the power supply device. Therefore, the phase difference detection method according to the present invention is
Even if the frequency of the power supply device varies, the phase difference from the commercial power supply can be accurately detected. In addition,
The PI control system 11 is composed of a proportional element K _P and a first-order lag integration element K _S / (1 + T _S ), and PI-controls and outputs the operation output of the summing point 10. This is a known technique.

[0009]

As described above, the phase difference detection method according to the present invention detects the phase difference between the output frequency of the power supply device and the frequency of the commercial power supply operating in parallel through the voltage detection circuit and the phase comparator. Further, after the frequency is corrected by the multiplier, the algebraic sum with the deviation reference amount of the preset phase is obtained, and the PI controlled detection value is converted into a high frequency signal in the VCO and fed back to the control circuit of the power supply device It is a thing. Therefore, the phase difference can be accurately detected even when the frequency variation occurs, and the reliability of the system can be improved. Further, when the control system described above has a digital configuration without requiring a complicated circuit configuration, it can be performed only by software processing without changing hardware.

[Brief description of drawings]

FIG. 1 is a block circuit diagram of a phase difference detection method showing an embodiment of the present invention.

2A and 2B are timing charts of frequency waveforms.

FIG. 3 is a block circuit diagram showing a conventional phase difference detection method.

[Explanation of symbols]

 1 commercial power supply 2 main circuit of power supply device 3 control circuit of power supply device 4 VCO 5 switching circuit 6, 7 voltage detection circuit 8 phase comparator 9 multiplier 10 addition point 11 PI control system

Claims (1)

[Claims] 1. A means for detecting an output voltage of a power supply device that operates in synchronism with a commercial power supply and the commercial power supply voltage; a means for comparing the two detected voltages in a phase comparator and detecting a phase difference between them. Multiplying means for correcting the detected value of the phase difference by the phase comparator based on the rated frequency according to the output frequency of the power supply device, and an algebraic sum of the preset phase deviation reference amount and the arithmetic output by the multiplying means. A phase difference which is configured by means for calculating and means for inputting an output obtained by controlling the calculation output by the calculating means by the PI control method to the VCO and feeding it back to the control circuit of the power supply device as a high frequency signal. Detection method.