JPH1014132A - Uninterruptible power supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent rush current from flowing in a normally opened contact and thereby eliminate a rush current preventive circuit by closing the normally opened contact after detecting a phase and a voltage of an AC input power and operating a converter as an inverter by means of a controller and generating the voltage of the same phase as the AC input power on a cable way. SOLUTION: In an uninterruptible power supply, power from an AC power supply 1 is received and the AC voltage is converted to DC voltage by a converter 6 and then the DC voltage is smoothed by capacitors 8a, 8b and them the smoothed DC voltage is input into an inverter 7 and the DC voltage is converted by the inverter into AC voltage synchronous with the input AC power and then higher harmonic wave components of the AC voltage are removed by a filter 10 and finally the AC voltage with no higher harmonic wave components is output. In such an uninterruptive power supply, an AC voltage driving relay 2 is installed which is driven by a normally closed contact 14 which is operated by an auxiliary power supply 16 and whose normally opened contact 2a is installed at the input power 1 side and operating coil 2b is installed closer to the converter 6 than the normally opened contact 2a and which turns AC input on and off. Since the driving coil 2b of the AC voltage driving relay 2 is installed closer to the converter 6 than the normally opened contact 2a, the driving coil 2b of the AC voltage driving relay 2 does not operate when the normally opened contact 2a is in an open state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an input switch of an uninterruptible power supply having a built-in converter or inverter.

[0002]

2. Description of the Related Art Conventionally, an input switch of an uninterruptible power supply is implemented by a circuit as shown in FIG. The uninterruptible power supply receives the AC input power 1 and converts the received commercial power into a DC voltage by the converter 6. The voltage converted into DC is converted again into AC voltage by the inverter 7 and the output filter 10.

When the AC input power supply 1 is out of power, the relay 22 is opened to cut off the voltage of the AC voltage driving coil 21b, the contact 21a is opened, the switch 12 is turned on by the signal of the controller 26, and the converter 6 is turned on. Is started by the controller 26 and controlled as a boost converter operation together with the reactor 9 to boost the DC voltage of the battery 13. The boosted DC voltage is smoothed by the capacitors 8a and 8b, converted into an AC voltage having the same frequency as that of the AC input power supply 1 by the inverter 7, and supplied to the load 32 by removing high frequency noise by the filter 10. At this time, the switch for turning on / off the input power of the uninterruptible power supply is an AC voltage drive type relay 21, and the drive voltage of the relay 21 is the AC input voltage. When the control unit 26 turns on the normally open switch 22 by the operation stop changeover switch 23, an AC input voltage is applied to the drive coil 21 b of the relay 21, and the drive coil 21 b operates to activate the relay 21.
Is closed to supply power to the converter 6.

In order to suppress the inrush current of the capacitors 8a and 8b when the contact 21a of the relay 21 is turned on, the contact 21a
A rush current prevention circuit 24 is provided between a and the converter 6. The inrush current prevention circuit 24 includes a current reducing resistor 24a and a bidirectional switch 24b. When the contact 21a is turned on, the bidirectional switch 24b is off. That is, when the switch 21a is turned on, the rush current flowing through the capacitors 8a and 8b is reduced by the current reducing resistor 24a. The inrush current disappears,
When the input current returns to the steady state, the control unit 26 turns on the bidirectional switch 24b. By turning on the bidirectional switch 24b, the input current passes through the bidirectional switch without passing through the current reducing resistor 24a.

[0005]

SUMMARY OF THE INVENTION
Since the drive coil 21b of the AC voltage drive relay 21 to be turned off is directly connected to the AC input, a voltage is applied to the drive coil 21b while the contact 22 is closed,
Since the contact 21a is closed, the rush current flows at this time.

[0006]

[MEANS FOR SOLVING THE PROBLEMS] Receiving AC input power,
A converter converts the AC voltage of the AC input power supply to a DC voltage, smoothes the DC voltage with a capacitor,
In the uninterruptible power supply for converting the DC voltage into an AC voltage synchronized with the AC input power supply voltage by an inverter and supplying the AC voltage to a load, the uninterruptible power supply of the present invention includes a normally open contact and an AC voltage driving coil. An AC voltage drive relay, wherein the normally open contact is connected between the AC input power supply and the converter, and the AC voltage drive coil is connected to the converter with respect to the normally open contact.
A controller for controlling both operation of the converter and the inverter, a pre-charge circuit for pre-charging the capacitor, and a control for converting the voltage of the capacitor insulated to a voltage suitable for operation of the controller. And an auxiliary power supply circuit for supplying power to the unit.
That is, since the drive coil of the relay is disposed closer to the converter than the normally open contact, the drive coil of the relay does not operate when the normally open contact is open.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an uninterruptible power supply according to the present invention will be described with reference to FIGS.

The uninterruptible power supply according to the present invention has an AC input power supply 1
And a normally-open contact 2a for opening and closing the coil 2b driven by an AC voltage between the electric circuits 61 and 64 to cut off the AC input power supply 1 from the electric circuit 61, and to apply the voltage to the driving coil 2b according to a command from the controller 11. A normally closed contact 14 for turning on and off a voltage between the electric circuit 61 and the electric circuit 64, a reactor 9 and a converter 6 for converting the AC voltage of the AC input power supply 1 into a DC voltage while boosting the AC voltage, and a DC voltage of the converter 6 Capacitors 8a and 8b for smoothing output
An inverter 7 for receiving a DC voltage smoothed by the capacitors 8a and 8b and converting the AC voltage to an AC voltage; a filter 10 for removing high-frequency noise of the voltage converted to AC by the inverter 7; A voltage detector 15 which detects a frequency and sends a detection signal to the controller 11; and a controller 11 which detects the voltage of the capacitors 8a and 8b.
An auxiliary power supply 16 for converting to a low voltage suitable for the operation of the power supply, a storage battery 13 for supplying power to the converter 6 when the AC input power supply 1 is in a power failure, and a power supply of the storage battery 13 for the converter 6 when the AC input power supply 1 is in a power failure. A switch 12 that is turned on so as to be supplied, and is connected to the AC input power supply 1, and rectifies the AC voltage of the AC input power supply 1 by the current reducing resistor 3a and the rectifying elements 3b and 3c to charge the capacitors 8a and 8b. In response to the signal of the circuit 3 and the voltage detector, the ON / OFF of the normally closed contact 14 is controlled by the command of the operation stop changeover switch 17, the ON / OFF control of the normally open contact 2a, the ON / OFF control of the current of the storage battery 13 and the gate of the switch 12 A controller 11 for controlling a signal and controlling the converter 6 and the inverter 7 and a filter 10 for removing high-frequency noise from the output of the inverter 7 are provided. 32 is a uninterruptible power supply for supplying AC power to.

That is, since the drive coil 2b of the AC voltage drive relay 2 is disposed closer to the converter 6 than the normally open contact 2a, the drive coil 2b of the AC voltage drive relay 2 is opened when the normally open contact 2a is open. Will not work.

When the AC input power supply 1 fails or loses its voltage, the input voltage detector 15 detects that there is no input voltage, and the controller 11 opens the normally closed contact 14. The drive voltage of the drive coil 2b of the AC voltage drive relay 2 is lost, and the normally open contact 2a is opened. Thereafter, the controller 11 turns on the switch 12, boosts the DC voltage of the storage battery 13 by the reactor 9 and the converter 6, and supplies the DC voltage to the inverter 7. The inverter 7 supplies a voltage having the same frequency as the AC input power supply 1 to the output. When the AC input power supply 1 returns from the power failure state, a short circuit between the voltage of the storage battery 13 and the voltage of the AC input power supply 1 does not occur even when the switch 12 is closed because the contact 2a is open. .

The pre-charging circuit 3 comprises a current reducing resistor 3a connected to the AC input power supply 1 and rectifying diodes 3b and 3c. The current supplied from the AC input power supply 1 is reduced by the reduction resistor 3a,
It is rectified by c. This rectified current charges the capacitors 8a and 8b. Number 1 of capacitors 8a and 8b
The voltage of 00V is converted by the auxiliary power supply 16 into a low voltage of about 10 V for operating the controller 11, and
Power supply.

FIG. 2 shows an operation sequence of the controller 11 when starting the uninterruptible power supply. In a period 51 in FIG. 2, the AC input power supply 1 supplies power, and the operation stop switch 1
Before the switch 7 is turned on, the preliminary charging circuit 3 operates to charge the capacitors 8a and 8b, and the controller 11 operates in a standby state by the auxiliary power supply. In the period 52, the switch 17 is turned on and the switch 12 is turned on by a command from the controller 11, and the converter 6 operates as a boost converter, boosts the voltage of the storage battery 13 and increases the voltage of the capacitors 8a, 8b.
To increase the voltage of the electric circuit 62 and the electric circuit 63 with respect to the electric circuit 64 to a voltage that always operates as an uninterruptible power supply. At this time, the voltage of the electric circuit 61 is equal to the voltage of the storage battery 13 if the voltage drop due to the switch 12 is ignored. When the voltage of the electric circuit 62 and the electric circuit 63 rises to a voltage that always operates as the uninterruptible power supply, the switch 12 is turned off by a command from the controller 11 to switch the operation of the converter 6 to the inverter operation. The same voltage is generated in the electric circuit 61 in synchronization with the voltage of. At this time, the power source for the inverter operation is the capacitors 8a and 8b charged during the converter period 52. After the voltage of the electric circuit 61 is established by the converter 6 during the inverter operation period 53, the relay contact 14 is closed by the controller 11, and the AC voltage generated by inverting the converter 6 is driven by the driving coil of the AC voltage driving relay 2. 2b to close the normally open contact 2a. By closing the normally open contact 2a, the AC input power supply 1 is connected to the electric circuit 61, and power is supplied to the electric circuit 61 from the AC input power supply 1. As soon as the normally open contact 2a is closed, the controller 11 switches the converter 6 from the inverter operation period 53 to the converter operation period 54 by the controller 11. In accordance with a command from controller 11, converter 6 operates as a boost converter during converter operation period 54 of converter 6, and inverter 7 converts a DC voltage supplied from converter 6 into an AC voltage synchronized with AC input power supply 1, and a filter. The high frequency noise of the voltage is removed by 10 and supplied to the load 32.

The voltage and the phase of the AC input power supply 1 are detected by the voltage detector 15, and the converter 6 is operated as an inverter by the controller 11 to generate a voltage having the same phase value as the power supply 1 on the electric circuit 61 to be normally open. No rush current flows when the contact 2a is closed.

[0014]

According to the present invention, the phase and voltage of the AC input power supply 1 are detected, and the converter 6 is operated by the controller 11 as an inverter.
After a voltage having the same phase as that of the AC input power supply 1 is generated in the transmission line 61, the normally open contact 2a is closed, so that no rush current flows through the normal contact, and the rush current prevention circuit 24 becomes unnecessary.

[Brief description of the drawings]

FIG. 1 is a drawing of an embodiment of the present invention.

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

FIG. 3 is a drawing of an embodiment of the prior art.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 AC input power supply 2, 21 AC voltage drive relay 2a, 21a Normally open contact 2b, 21b Driving coil 3 Pre-charge circuit 3a Current reduction resistor 3b, 3c Rectification diode 6 Converter 7 Inverter 8a, 8b Capacitor 9 Reactor 10 Filter 11 Control 12 Switch 13 Storage battery 14 Normally closed contact 15 Voltage detector 16 Auxiliary power supply 17, 23 Operation stop changeover switch 22 Normally closed contact 24 Inrush current prevention circuit 24a Current reduction resistor 24b Bidirectional switch 26 Controller 32 Load

Claims (1)

[Claims] An AC input power supply is received, a converter converts an AC voltage of the AC input power supply into a DC voltage, a capacitor smoothes the DC voltage, and synchronizes the DC voltage with the AC input power supply voltage by an inverter. An uninterruptible power supply for supplying the AC voltage to a load after converting the AC voltage into a converted AC voltage, comprising a normally open contact of an AC voltage driving coil, wherein the normally open contact is connected between the AC input power supply and the converter. An AC voltage drive coil connected to the converter with respect to the normally open contact, an AC voltage drive relay, a controller for controlling both operations of the converter and the inverter, and precharging the capacitor. A pre-charging circuit and an auxiliary for insulatively converting the voltage of the capacitor into a voltage suitable for operation of the controller and supplying power to the controller. An uninterruptible power supply comprising an auxiliary power supply circuit.