JPH0593746A - Overcurrent detection circuit for single phase three-wire output in uninterruptive power source unit - Google Patents

Abstract

PURPOSE:To supply power to the fill rated capacity of a transformer free from a load sharing by detecting secondary output currents of the transformer separately in an uninterruptive power source unit containing the transformer for a single phase 3 wire output. CONSTITUTION:In an uninterruptive power source made up of a transformer for a single phase 3 wire output connected on the output side of a changeover switch 3, current detectors 5, 6 and 7 are arranged respectively on one wire of a 200V circuit and two wires containing no neutral wire of a 100V circuit. A detection circuit 8 is provided and adds up detection values of the current detectors 5, 6 and 7 to compare the results with an overcurrent set value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an overcurrent detection circuit in an uninterruptible power supply device having a single-phase three-wire output circuit.

[0002]

2. Description of the Related Art FIG. 3 is a block circuit diagram of a conventional uninterruptible power supply for supplying electric power to a single-phase three-wire type load, which includes a rectifier 101, a storage battery 110, an inverter 102,
Electric power was supplied to the single-phase three-wire load by connecting the single-phase three-wire output transformer 104 to the output side of the uninterruptible power supply 109 configured by the changeover switch 103 and the bypass circuit 108. A current detector 111 is provided on the input side of the transformer 104, and the detected value is compared with an overcurrent set value in a detection circuit 107. If the detected value is larger than the overcurrent set value, the changeover switch 3 causes The inverter power supply was switched to direct power supply to protect the inverter. Further, the single-phase three-wire output circuit of the transformer 4 is provided with switches 105 and 106, and
4 had overload protection.

[0003]

In the single-phase three-wire output circuit shown in FIG. 3, 200 is placed between terminals 112 and 114.
V, 100V is applied between the terminals 112 and 113 and between the terminals 114 and 113. Therefore, the switch 10
Since a load current of 200 V and a load current of 100 V flow through 5 and 106, a load current corresponding to the rated capacity of the transformer 104 may not be supplied depending on the distribution of the load of 200 V and the load of 100 V. For example, 10 of the transformer 104
When a rated current is applied between the 0V output terminals 112 and 113,
Since current cannot flow between the 200V output terminals 112 and 114, only half of the rated capacity of the transformer 104 can supply power to the load. The present invention has been made to solve the above-mentioned drawbacks, and an overcurrent for a single-phase three-wire output that can be supplied until the total of 200V supply load and 100V supply load reaches the rated capacity of the transformer. It is intended to provide a detection circuit.

[0004]

In order to solve the above-mentioned problems, the single phase 3 in the uninterruptible power supply device according to the present invention.
The overcurrent detection circuit for line output is an uninterruptible power supply device in which a single-phase three-wire output transformer is connected to the output side of a changeover switch.
A current detector is provided for each of the two wires that do not include the neutral wire of the output circuit, and the detected values of the three current detectors are DC-converted, waveform-shaped and added, and the added value is set to a preset overcurrent. The overcurrent in the single-phase three-wire output circuit is detected by comparing with the set value.

[0005]

Operation: Two detection values of the 100V current detector are DC-converted and waveform-shaped and added, and the detection value of the 200V current detector and the addition value of the 100V current detector which are also DC-converted and waveform-shaped are added together. Add in. As a result, the total output current supplied from the transformer 4 to the load can be detected by the three current detectors. Therefore, the overcurrent in the output circuit of the transformer 4 can be detected by comparing the detected value of the total output current with the overcurrent set value in the comparison circuit provided in the detection circuit 8.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block circuit diagram showing a configuration of an overcurrent detection circuit in an uninterruptible power supply device including a single-phase three-wire output transformer according to the present invention.

In FIG. 1, an uninterruptible power supply unit composed of a rectifier 1, a storage battery 10, an inverter 2, a bypass circuit 9 and a changeover switch 3 has a built-in transformer 4 having a single-phase three-wire output circuit. Transformer 4 of 200
The current detector 5 is provided in one line of the V circuit, and the current detectors 6 and 7 are provided in two lines of the 100 V circuit which do not include the neutral line. The current detection values 1, 2 and 3 of the three current detectors 5, 6 and 7 are input to the detection circuit 8.

FIG. 2 is a block circuit diagram showing the structure of the detection circuit. In FIG. 2, the 100V current detection values 2 and 3 are converted into DC by the rectifier circuits 12 and 13, respectively, and the resistors 22, 25, 26, the diode 20 and the capacitor 18 are converted.
Buffer circuit 1 synthesized in a waveform shaping circuit consisting of
The detected value V ₂ is output via 5. Further, the 200V current detection value 1 is converted into DC in the rectifier circuit 11, and the resistance 2
The detection value V ₁ is output via the buffer circuit 14 and the waveform shaping circuit including the diodes 1, 23, 24, the diode 19, and the capacitor 17. The above-mentioned two detection values V ₁ and V ₂ are added in the adder circuit including the operational amplifier 16 and the resistors 29 and 30 to output V _0. This detection value V ₀ is irrespective of the load sharing of the transformer 4, The total supply capacity from 4 is shown.

The detection circuit 8 has a built-in comparison circuit (not shown) for comparing the detection value V ₀ with an overcurrent setting value. When an overcurrent is detected, a control signal for switching the changeover switch is controlled. Is output. As described above, since the detected value V ₀ is the added value of V ₁ and V ₂ , the transformer 4 is always used.
To the load. If the overcurrent set value is set to the rated capacity of the transformer 4, electric power can be supplied to the load up to the rated capacity of the transformer 4 regardless of load sharing.

[0010]

The overcurrent detection circuit for single-phase three-wire output in the uninterruptible power supply according to the present invention is an uninterruptible power supply configured by connecting a transformer for single-phase three-wire output to the output side of the changeover switch. , 200V circuit of the transformer and 1
The 00V circuit is provided with a total of three current detectors, the detected current values are added in the detection circuit, and the overcurrent detection is performed by comparing the detected current values with the overcurrent detection value in the comparison circuit.
Therefore, there is an advantage that the power can be supplied up to the rated capacity of the transformer regardless of the distribution of the load that is the secondary output of the transformer.

[Brief description of drawings]

FIG. 1 is a single phase 3 of an uninterruptible power supply according to the present invention.
The block circuit diagram which shows the structure of the overcurrent detection circuit for line outputs.

FIG. 2 is a block circuit diagram showing a configuration of a detection circuit according to the present invention.

FIG. 3 is an overcurrent detection block circuit diagram for single-phase three-wire output in an uninterruptible power supply according to a conventional technique.

[Explanation of symbols]

 1 Rectifier 2 Inverter 3 Changeover switch 4 Transformer 5, 6, 7 Current detector 8 Detection circuit 9 Changeover switch 10 Storage battery

Claims (1)

[Claims] 1. An uninterruptible power supply comprising a rectifier, a storage battery, an inverter, a bypass circuit, and a changeover switch, wherein a single-phase three-wire output transformer is connected to the output side of the changeover switch. A current detector is provided on each of the two wires not including the neutral wire in the two sets of 100V output circuits consisting of one wire and three wires of the 200V output circuit of the transformer, and the detection value of each of the current detectors is converted into a direct current, Further, a waveform shaping is performed and addition is performed, and a detection circuit for detecting the overcurrent of the transformer is provided by comparing the added value with a preset overcurrent setting value. Overcurrent detection circuit for phase 3 wire output.