JPH02231962A - Power supply equipment capable of parallel operation - Google Patents

Abstract

PURPOSE:To enable an economical parallel operation with high general-purpose properties by operating one power supply equipment as a master in the mode of voltage control and by causing the first switch of another power supply equipment to select the current sensing signal of an inverter and the second switch to select the current sensing signal of said inverter so that said equipment is operated in the mode of current control. CONSTITUTION:A power supply 20 compares the voltage reference signal Vr of its reference signal generator circuit 9 and the detected signal Vf of the output voltage of an inverter 2 to operate as a voltage control. On the other hand, the reference signal generator circuit 5 of a power supply equipment 21 sets the current sensing signal If of said power supply 20 inputted to the terminal IR as a current reference signal Ir to compare it with its current sensing signal If to operate as a current control. When the current reference Ir in the rated current of each power supply and the signal level of current sensing If thereof are standardized and selected to be identical, the ratio of a load main current to the rated current of each power supply is made equal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a power supply device, and particularly to a power supply device that enables parallel operation.

(Prior Art) An uninterruptible power supply (hereinafter referred to as UPS) has a general configuration in which AC voltage and DC voltage are backed up by a battery or the like. Therefore, since each UPS performs voltage control and frequency control, when a plurality of UPSs are operated, a UPS suitable for each load capacity is selected and each UPS is operated independently.

(Problem to be solved by the invention) However, since conventional UPS cannot be operated in parallel, when the load capacity increases due to equipment expansion or change, it is necessary to replace it with a new UPS that can accommodate the increased capacity. Economic investment is forced.

Furthermore, if a UPS capable of parallel operation is custom-ordered, the special specifications will be expensive and uneconomical.

SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply device that switches control modes with a simple configuration and is inexpensive, economical, and highly versatile and capable of parallel operation.

[Structure of the invention]

(Means for solving the problem) In a device equipped with an inverter that reversely converts current voltage,
a first switch that selects either the voltage reference signal of the inverter or a current detection signal of another inverter; a second switch that selects either the voltage detection signal or the current detection signal of the inverter; 1 switch and the second
A voltage/current control circuit capable of controlling in either voltage control mode or current control mode using the signal selected by the switch as a reference signal and a feedback signal is provided to configure a power supply device capable of parallel operation.

(Function) When operating only one power supply device with the above configuration, the first
The voltage reference signal of the inverter is selected by the switch, and the voltage detection signal is selected by the second switch, so that the inverter is operated in the voltage control mode.

In addition, when operating multiple units, only one unit is operated as the master in the above voltage control mode, and the first switch of the other power supply units operated in parallel selects the current detection signal of the master inverter, and Switch No. 2 selects the current detection signal of the inverter to operate in a current control mode, and performs follow-up control of the output current of the master power supply device.

(Example) An embodiment of the present invention is shown in FIG.

In the figure, 1 is a converter that converts AC voltage Vin to DC voltage Vd, 2 is an inverter that converts DC voltage Vd to AC voltage Va, and 3 is a voltage control circuit (VC) that detects the internal reference signal Vdr and voltage. The signal Vdf detected by the circuit (VD) 4 is compared and the converter 1 is adjusted to control the DC voltage Vd. Reference numeral 5 denotes a voltage/current control circuit (VCC) which compares a reference signal Sr with a voltage or current feedback signal Sf to adjust the inverter 2 and control the voltage Va or current Ia.

Reference numerals 6 and 7 are circuits for detecting the voltage and current of the output of the inverter 2. A synchronization detection circuit (SYD) 8 detects a synchronization signal SY from the AC voltage Vin input to the converter 1. A reference signal generating circuit (RG) 9 outputs a sine wave signal Vr having a constant peak value synchronized with the synchronizing signal SY. 1o and it are changeover switches for setting either voltage control or current control mode.

Note that the DC voltage Vd is backed up by a battery (not shown), and even if the synchronization signal SY disappears, the RG9 continues to output the sine wave signal Vr at the previous synchronization frequency f by free-running oscillation.

Figure 1 shows an example in which two UPSs of this embodiment configured as described above are operated in parallel, with UPS 20 being the master.
This is an example in which S21 is set as a slave. In this case, selector switch 1 of UPS 20, which is the master
0. 11 selects ω and is set to voltage control mode, and the selector switch 10 of the UPS 21 which becomes the slave.
11 selects ■ and is set to the current control mode.

In addition, the current detection signal If of UPS ZO is output to the terminal IF, and is connected to the terminal IR of the UPS 21 via the external wiring 40.
is input.

With the above configuration, is VCC 5 of UPS20 the voltage reference of RG9? Vr and the detection signal Vf of the output voltage of inverter 2
Compare and operate as voltage control.

On the other hand, the UPS 21 VCC5 connects the human-powered current detection signal If of the UPS 20 to the current reference signal Ir.
It compares with its own current detection signal If and operates as current control.

Current reference Ir and current detection I at the rated current of each UPS
If the f signal level is standardized and selected to be the same, each UPS
The ratio of load current to rated current becomes equal. Therefore, the output currents Ia1 and Ia2 of UPS20 and UPS21
is supplied to the load 31 according to its capacity ratio, and the load ratio is automatically balanced.

FIG. 2 is an embodiment of a detailed circuit of VCC 5 and its surroundings. In this embodiment, a transformer T is included in the inverter 2.
r is provided, and an alternating current voltage Va is output through the secondary winding US2, and the output voltage is detected by the secondary winding vs2. Further, the output current Ia is detected by a current transformer 7. Inside VCC 5, there are control amplifiers C^1, CA2 and summing amplifier S.
A is provided, and a PWM control circuit Pw is provided according to the output of SA.
C controls inverter 2.

? A capacitor C is connected in parallel to the secondary winding USE of the lance Tr, and the current flowing through the capacitor C is transferred to a current transformer CT.
is detected as signal Ccf. RG9 outputs a current reference signal Ccr that is 90° in phase ahead of the voltage reference signal Vr, and the control amplifier CAL compares this signal Ccr and the signal Ccf, and outputs a control signal ΔE to reduce the deviation. .

The control amplifier CA2 receives the aforementioned reference signal Sr and feedback signal Sf, outputs a signal ΔE2 corresponding to the deviation thereof, and inputs the signal ΔE2 together with the above-mentioned 8E2 to the addition amplifier SA. Therefore, in the embodiment shown in FIG. 2, a current control system for the current flowing through the capacitor C is inserted in parallel, and since the output voltage Va is directly applied to the capacitor C, it acts as a voltage control system, and the amplifier CAL is used for voltage control. This is effective for improving response and waveform.

In this case, selector switch 10. When operating as a slave by setting 11 to ■, an interlocking switch 12 is provided to suppress the gain so that the voltage control action by the amplifier CAL does not conflict with the current control.

According to this embodiment, stable control can be performed in both voltage control and current control modes.

Another embodiment of the invention is shown in FIG.

In this embodiment, an automatic switching circuit (ACHG) 13 that automatically switches the control mode is newly installed, and an abnormality signal Fd from RG9 and a failure signal Fν of the voltage control system (not shown) are provided.
The changeover switches 10 and 11 are switched in response to a forced switching command Fc inputted from the outside.

In this case, the AC IG 13 selects the changeover switch 10.11 to select ■ for the UPS 20 (master) and select ■ for the UPS 21 (slave) in a normal operating state.

When an abnormality occurs in the UPS 20, the ACHG 13 switches the switching switch (IO, TT to output) and outputs a forced switching command to the Act{G13 of the UPS 21 via the external wiring 42.As a result, the ACHG 13 of the UPS 21 The changeover switches 10 and 11 are forcibly switched to the position (■).Therefore, the UPS 20 becomes the current control (slave), the UPS 21 becomes the voltage control (master), and parallel operation is continued.

According to this embodiment, even if a failure occurs in the voltage control system of the master, power can be supplied to the load, making it possible to provide a highly reliable power supply device.

〔Effect of the invention〕

According to the present invention, a power supply device that can be easily operated in parallel can be obtained, and power supply devices with a capacity commensurate with the increased load can be operated in parallel, so that operational efficiency can be improved.

Furthermore, since they can be manufactured with the same type of standard specifications, the power supply device can be manufactured with high productivity, low cost, and high versatility.

Furthermore, during parallel operation, when an abnormality occurs in the voltage control of the master, the slave can be made the master, resulting in a highly reliable power supply device.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of a power supply device according to the present invention, FIG. 2 is a partial detailed diagram of FIG. 1, and FIG. 3 is a diagram showing another embodiment of the present invention. 1...Converter 2...Inverter 3...Voltage control circuit 4, 6...Voltage detection circuit 5...Voltage/current control circuit 7...Current detector 8...Synchronization detection circuit 9 ...Reference voltage generation circuits 10 to 12...Changing switch l3...Automatic switching circuit agent Patent attorney Noriyuki Ken Yudo Ken Deshimaru

Claims (1)

[Claims] In a device equipped with an inverter that converts an alternating current voltage into a direct current voltage and then converts it back into a constant voltage constant frequency alternating current voltage, a first step is to select either the voltage reference signal of the inverter or the current detection signal of another inverter. a second switch that selects either the voltage detection signal or the current detection signal of the inverter; and a voltage detection signal using the signal selected by the first switch and the second switch as a reference signal and a feedback signal. A power supply device capable of parallel operation, characterized by being provided with a voltage/current control circuit that can be controlled in either control mode or current control mode.