JPS59181926A - Synchronizing system of inverter - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a synchronization method for synchronizing an inverter output with a commercial power source in a power supply facility that switches an inverter and a commercial power source in full-instantaneous parallel operation to supply power to a load.

In a control method that performs instantaneous parallel operation by matching the 9 voltage frequencies of the inverter and commercial power supply (line) and turning on the switch to momentarily parallel the power supplies without switching between the inverter and the commercial power supply, the inverter shown in Figure 1 Synchronous control makes phase matching control difficult. In the figure, the output voltage of the inverter main circuit / is controlled by its direct current side or gate Norse width control, and the output frequency and phase are controlled by gate control. This gate control is based on the line voltage V. and inverter output voltage V1 are respectively detected by the voltage detector 2.3, and the phase difference between the detected voltages is detected as a corresponding voltage signal by the total phase difference detector l. It is subtracted and amplified by an amplifier 6. The output of the amplifier B is converted into a corresponding frequency signal by the voltage controlled oscillator 7 and input to the gate circuit for frequency and phase control, and the output of the gate circuit controls the on/off of each phase switching element of the inverter main circuit. Ru. After receiving a switching command from the line to the inverter, the synchronization control circuit 9 monitors the output of the amplifier t, and when the output reaches zero, that is, the line and inverter output phases are adjusted to the range set in the setting device S. When it matches, switch 10□f! :10L
are connected in parallel, and after the time required to transfer the load to the inverter side, the switch lOL is disconnected.

However, in this conventional synchronization method, the switch 10L910
When , ramps at the time of switching, the horizontal points of voltage detectors 2 and 3 become the same and the amount of phase difference becomes zero, making it impossible to control the phase alignment by the phase difference detector. One way to solve all of this is to detect the active power and reactive power and control the cross current between the line and the inverter, but in this case the control circuit is complicated, reducing reliability and increasing cost. There were drawbacks.

The present invention provides a synchronization method that enables reliable and easy phase control by synchronizing the output of a voltage control amplifier with the line voltage and detecting a phase difference even in the lamp of a switching device. With the goal.

FIG. 2 is a single-phase inverter circuit diagram showing one embodiment of the present invention. In the figure, the same parts or parts having the same functions as the first prisoner are indicated by the same reference numerals. In Figure 2,
The output of the voltage controlled oscillator 7 is frequency-divided by a frequency divider circuit /l to an appropriate frequency, and this frequency-divided output is taken out as a timing signal by a monostable multivibrator saw and sent to one phase comparison input of the phase difference detector Hiroshi. be done. The other input of the phase difference detector l is provided with a line voltage phase signal by a voltage detector l.

On the other hand, the output of the frequency divider circuit /l is used as the phase 9 frequency control input of the triangular wave generating circuit 13, and the constant amplitude triangular wave output of the triangular wave generating circuit 13 is used as a comparison reference of the comparator lda. The voltage V of the output of the inverter / is detected by the voltage detector /3, this detected voltage is compared with the set value of the inverter output voltage setter /6, and calculation is performed by the voltage control amplifier /7. The output of 7 is used as a comparison input of comparator Lda. The comparator/da compares the levels of the triangular wave signal of the triangular wave generating circuit/3 and the voltage control output of the voltage control amplifier 17 to obtain a pulse signal that matches the inverter output voltage 2 frequency 9 phase with those of the line. This Norculus signal is input to the gate control of each gate circuit, and is distributed and amplified by the gate circuit as a gate pulse for each switch of the inverter I.

In this way, as a PLL circuit for phase matching between the line side and the inverter side, the switching device 10L, IO, It is possible to compare the phase difference regardless of the closing state of the phase shifter, thereby making it possible to perform stable phase control, that is, reliable synchronization.

FIG. 3 shows waveforms of various parts in FIG. 2. For the output of the voltage controlled oscillator 7, a divided output is obtained between frequency division #8//, and a phase logic output is obtained from the rise timing of this frequency divided output to the monostable multivibrator 72, and this output and the line voltage signal are A phase difference detector Hiroshi performs a phase comparison with the zero cross point signal of , and the PLL circuit is configured to completely control the output phase of the voltage controlled oscillator 7 according to the result of this phase comparison. TonoALL
Since the circuit TE does not directly detect the inverter output voltage phase for phase comparison, even if the switching devices IOL and IO are instantaneously parallel, the input to the phase difference detector GU will not become like a four-signal signal. This enables reliable phase comparison and, in turn, inverter output phase matching. Note that the triangular wave output in the m3 diagram is used for gate control including the voltage control system of the inverter, and the output voltage is also controlled all at once by controlling the inverter's pulse width.
, Y gate signal is created! llll output, and the inverter output is aligned to the midpoint of the phase logic output.

As described above, the present invention relates to the inverter phase.

The inverter output phase is determined by comparing the phase of the frequency control signal phase timing signal and the line voltage signal.

Since the frequency control signal is obtained, phase control is prevented from becoming impossible even in instantaneous parallel operation inverters, and there is an effect that reliable synchronous switching can be performed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing the entire conventional synchronization system, FIG. 2 is a circuit diagram showing an embodiment of the present invention, and FIG. 3 is a waveform diagram of each part of FIG. 2. /... Inverter main circuit, λ... Voltage detector, G...
...Phase difference detector, S...Phase setter, 6...Amplifier, 7...Voltage controlled oscillator,! ...gate circuit, 7
...Synchronous official control circuit, 10L, 10. ...Switcher, /C...Frequency divider, /2--- Monostable multivibrator, /3...Triangular wave generation circuit, /Hiroshi...Comparator, /3...Voltage detector, /A...voltage setting device,
/7...Voltage control amplifier. Figure 2 Figure 3

Claims (1)

[Claims] In power supply equipment that supplies power to a load by instantaneously switching between a commercial power source and an inverter in parallel operation, the phase and frequency of the phase control signal are controlled by comparing the phase difference between the voltage phase of the commercial power source and the phase of the inverter's phase control signal. PLL to do
An inverter synchronization method, comprising: a circuit, and when the phase difference comparison result is within a predetermined range, the commercial power source and the inverter are operated in parallel at all instants to transfer to the inverter side.