JPH0550952U - Uninterruptible power system - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize a UPS in which the potential difference between the inverter output and the output of the AC input bypass circuit does not increase when the switches are switched. [Arrangement] AC / DC converter 1, battery 3 as an auxiliary power supply at the time of power failure, DC / DC converter 2 for voltage adjustment, and DC output of DC / DC converter 2
Inverter 4 for converting into
Switching circuit 1 for switching between input and output of bypass circuit 8
2 and the control circuit 1 by detecting an abnormality in the output of the inverter 4.
1 and a control circuit 11 that receives the fault signal to switch the switching circuit 12 and outputs a control signal that stops the operation of the inverter 4 during the switching time of the switching circuit 12. .

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an uninterruptible power supply, and more particularly to an uninterruptible power supply that prevents a potential difference from increasing when switching to a bypass.

[0002]

[Prior Art]

 Nowadays, highly developed computer systems are widely spread in the general public, and in such a system, an uninterruptible power supply is likely to result in a great public confusion if a power outage occurs. It supplies reliable power.

FIG. 3 is a block diagram of such an uninterruptible power supply system with a constant inverter power feeding type bias switching. In the figure, 1 is an AC / DC converter that converts an AC input into DC, and 2 is a DC / DC converter that receives the output of the AC / DC converter 1 and outputs DC of a desired voltage. The output voltage of the battery 3 is also input to the DC / DC converter 2, and the battery 3 supplies a DC voltage to the DC / DC converter 2 during a power failure and is charged by the AC / DC converter 1 when energized.

The output of the DC / DC converter 2 is converted into an AC voltage by the inverter 4, and is supplied to the external circuit as a UPS (uninterruptible power supply) output via the b contact-a contact of the relay 5.

When an abnormality occurs in the inverter 4 or a large current flows that may damage the inverter 4, the abnormality detection circuit 6 detects and inputs the information to the control circuit 7. The control circuit 7 sends a relay switching control signal to the relay 5 to switch the relay 5 to the c contact side, and the bypass circuit 8 outputs the AC power directly.

[0006]

When the control circuit 7 switches the relay 5, since the AC input from the bypass circuit 8 and the output of the inverter 4 are asynchronous, the AC input of the bypass circuit 8 and the output of the inverter 4 are not provided. If the phase is reversed, the potential difference between the b contact and the c contact of the relay 5 becomes large, and when the relay 5 switches, the b contact and the c contact are directly connected by an arc or the like, and the inverter A large current may flow between the output of 4 and the bypass circuit 8.

FIG. 4 is a timing chart showing the relationship between the output of the bypass circuit, the voltage of the output of the inverter, and the UPS output. In the figure, (a) is a diagram of the output voltage waveform of the bypass circuit at the c contact of the relay 5, (b) is a diagram of the output voltage waveform of the inverter 4 at the b contact of the relay 5, and (c) is It is a figure of the output voltage waveform of UPS in a contact. Reference numeral 10 is a relay switching time. In the figure, at this relay switching time 10, the bypass circuit output has the maximum positive value and the inverter output has the maximum negative value. At this time, a voltage approximately twice the maximum value of each output voltage is applied between the b and c contacts of the relay 5, causing arc discharge and causing a large current to flow.

The present invention has been made in view of the above points, and an object thereof is to realize a UPS in which the potential difference between the inverter output and the output of the bypass circuit of the AC input does not increase at the time of switching the switch.

[0009]

[Means for Solving the Problems]

 The present invention, which solves the above-mentioned problems, includes an AC / DC converter that converts an AC input into a DC voltage, a battery that supplies the DC voltage instead of the AC / DC converter in the event of a power failure, and a DC voltage that is a desired voltage. In the uninterruptible power supply device having a DC / DC converter for converting to DC, an inverter for converting an output DC voltage of the DC / DC converter into an AC voltage, and an abnormality detection circuit for detecting an abnormality in the output of the inverter, A switching circuit that switches between the AC input and the output of the inverter when the output of the inverter is abnormal, and the switching circuit is switched by receiving the output of the abnormality detection circuit, and the output of the inverter is switched to the switching circuit. And a control circuit for outputting a control signal for stopping for a required time.

[0010]

[Action]

 When an abnormality occurs in the inverter output, the abnormality detection circuit detects the abnormality and sends the information to the control circuit. The control circuit sends a control signal to the switching circuit to switch the input circuit and sends a signal to the inverter to stop the operation for at least the switching time of the switching circuit. Prevents application of voltage.

[0011]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention. In the figure, the same parts as those in FIG. 3 are designated by the same reference numerals. In the figure, reference numeral 11 is a control circuit for controlling the operations of the inverter 4 and the switching circuit 12 in response to the output of the abnormality detection circuit 6 which detects the abnormal output of the inverter output.

Next, the operation of the embodiment thus configured will be described. The operation of the apparatus of this embodiment is substantially the same as that of the conventional apparatus shown in FIG. 3, except for the following points. That is, the control circuit 12 receives the output signal of the abnormality detection circuit 6 that has detected the output abnormality of the inverter 4, controls the switching circuit 12, and switches the UPS output from the output of the inverter 4 to the output of the bypass circuit 8.

Further, the control circuit 11 stops the operation of the inverter 4 for a fixed time period sufficient for the switching circuit 12 to switch the input voltage circuit. FIG. 2 shows a timing chart of the waveform of each part at this time. In the figure, (a) is the AC input waveform of the output of the bypass circuit 8, (b) is the output waveform of the inverter 4, and the output of the abnormality detection circuit 6 of (c) is input at the switching circuit switching time 10. The operation of the inverter 4 is stopped by the control circuit 11 for the operation stop period 21 of a time sufficient for the switching circuit 12 to switch the contacts. (D) is the UPS output of the output of the switching circuit 12 output by switching the output of the inverter 4 in (b) and the output of the bypass circuit 8 in (a) at the switching circuit time 10.

As is apparent from the figure, when the abnormality detection circuit 6 detects an abnormality and sends a signal to the control circuit 11, the control circuit 11 switches the switching circuit 12 and switches the inverter 4 to the input circuit. The operation is stopped for a sufficient time to switch. Therefore, since the inverter output voltage at the time of switching becomes 0 once, the maximum value of the potential difference between the contacts of both circuits in the switching circuit 12 becomes half of the maximum value in the conventional worst case, and the switching circuit 12 It is possible to avoid a state in which the load applied to the inverter is reduced and the AC input of the bypass circuit 8 is directly connected to the output of the inverter 4 due to an arc or the like.

[0015]

[Effect of the device]

 As described in detail above, according to the present invention, the short-circuit accident due to the arc, which occurs due to the large potential difference between the output of the bypass circuit of the switching circuit and the output of the inverter at the time of switching, does not occur, and the practical effect is large.

[Brief description of drawings]

FIG. 1 is a block diagram of an apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart of the operation of the apparatus of the embodiment.

FIG. 3 is a block diagram of a conventional UPS.

FIG. 4 is a timing chart of the operation of a conventional UPS.

[Explanation of symbols]

 1 AC / DC converter 2 DC / DC converter 3 Battery 4 Inverter 6 Abnormality detection circuit 11 Control circuit 12 Switching circuit

Claims (1)

[Scope of utility model registration request] 1. An AC / D for converting an AC input into a DC voltage.
A C converter (1), a battery (3) that supplies a DC voltage in place of the AC / DC converter (1) in the event of a power failure, a DC / DC converter (2) that converts the DC voltage into a desired voltage, An inverter (4) for converting an output DC voltage of the DC / DC converter (2) into an AC voltage, and an abnormality detection circuit (6) for detecting an abnormality of the output of the inverter (4).
A switching circuit (1) for switching between an AC input and an output of the inverter (4) when the output of the inverter (4) is abnormal.
2) and a control signal for receiving the output of the abnormality detection circuit (6) to switch the switching circuit (12) and stopping the output of the inverter (4) for the time required for switching of the switching circuit (12). An uninterruptible power supply comprising a control circuit (11) for outputting.