JPH0340717A - Phase-failure detection circuit - Google Patents

Abstract

PURPOSE:To detect phase-failure of polyphase AC input power source reliably by comparing a reference voltage proportional to the switched input voltage with the phase voltage of a polyphase AC input power source when the input voltage of the polyphase AC input power source is switched. CONSTITUTION:A reference voltage generating circuit rectifies and smooths the pulse voltage between terminals P and Q through a diode D15, a capacity C7 and resistors R18, R19, and the voltage divided by the resistors R18, R19 is provided as a reference voltage proportional to the input voltage. Each detected phase voltage V1 is compared with a reference voltage V2 through comparators 20, 21, 22, and phase-failure signals are outputted from the comparators 20, 21, 22 when the detected voltage V1 drops below the reference voltage V2. In this case, the reference voltage V2 is proportional to the three- phase AC input source voltage, and the reference voltage proportional to the input voltage is set automatically even if the input voltage is switched in a plurality of steps and thereby phase-failure of polyphase AC input power source can be detected reliably.

Description

[Detailed Description of the Invention] [Summary] This invention relates to an open-phase detection circuit that detects open-phase in a multi-phase AC input power source, and is capable of detecting open-phase in a multi-phase AC input power source even when the input voltage of the input power source is switched. Aiming at reliable detection with a simple circuit, we have developed a phase voltage detection circuit for each phase that detects the phase voltage of a polyphase AC input power supply, and a standard that generates a reference voltage proportional to the input voltage of the polyphase AC input power supply. a voltage generation circuit; and a phase-opening detection circuit for each phase that compares the output of the phase voltage detection circuit with the output of the reference voltage generation circuit and outputs a phase-opening detection signal when the output of the former becomes lower than the output of the latter. It was configured to have the following.

(Industrial Application Fields) DC stabilized power supplies for electronic communication devices, etc. that use a multiphase AC power source as human power convert AC input power into DC power and supply it to each circuit of the electronic communication device. , if one phase of the polyphase AC input power supply is open for some reason,
DC power is supplied to the load side with almost no effect, but
In the input side conversion section of the power supply device (for example, in the case of a switching power supply, the rectification smoothing circuit and switching circuit, etc.), other active phases supplement the current for the missing phase.
Since a current exceeding the steady maximum current flows and causes damage to circuit components, it is necessary to detect the occurrence of an open phase and take protective actions such as stopping the operation of the power supply as an abnormality in the input power supply.

In addition, demand has been increasing in recent years for input voltage switching type power supply devices that can handle cases where multiphase AC power supply voltages differ in Japan and other countries.

The present invention relates to an open-phase detection circuit used in a power supply device of an electronic communication device that receives a multi-phase AC power source as an input, and in particular, it reliably detects an open phase in a multi-phase AC input power source even when the input voltage is switched. The present invention relates to an open-phase detection circuit capable of detecting an open phase.

[Conventional technology]

Conventionally, when detecting an open phase in a three-phase three-wire system, as shown in FIG. 3, the AC input power line Ll.

L2. L3 is connected to open phase detection transformers Tl, T2 . T3 and each transformer TI, T2 . Conversion circuits 11, 12, and 13 that convert AC voltage to DC voltage are connected to the secondary side of T3, and each conversion circuit 1
1, 12.13 and the output signal of the reference voltage generation circuit 14 are compared by comparison circuits 15, 16.17,
The outputs of conversion circuits 11, 12, and 13 are reference voltage generation circuit 1
4, each comparison circuit 1516.
A configuration is adopted in which an open phase detection signal is output from 17.

In the above conventional circuit, AC input power supply lines Ll, L2
．． If the voltage value of L3 is changed, for example, AC400V
When changing from AC200V to AC200V, transformers Tl, T2 .
By changing the tap position of T3, each conversion circuit 1
1.12.13, it is configured to always output the same voltage.

[Problem to be solved by the invention]

However, in the conventional circuit, the AC input power line LL,
L2. When the input voltage value of L3 is changed in multiple stages, in order to make the output voltage of each conversion circuit 11, 12. work must be done.

Also, to make this tap switching work easier,
Input voltage switching circuit composed of changeover switches, etc.
However, such an input voltage switching circuit 10 and each transformer Tl, T2 . Since T3 and the like are relatively large parts and expensive, they are an obstacle to making the power supply device smaller, lighter, and cheaper.

Moreover, the base voltage generated by the reference voltage generation circuit 14 is provided with the reference voltage of each comparator circuit 15, 16, and 17.
When the input voltage of the AC input power source is switched, each conversion circuit 11, 12 . If the output voltages of converter circuits 11 and 13 are different, it may not be possible to reliably detect phase loss.
2.13 and each transformer TI, T2. T3 needs to have little variation and high accuracy.

In addition, in power supplies, a filter (not shown) is often inserted at the input end in order to remove noise from the AC input power supply, and such filters usually have a capacitor inserted between each phase. For this reason, even when a phase is open, the voltage from the phase that is not open goes around through this capacitor, so the open-phase power supply line does not drop to O■, and a slight voltage drop due to line impedance is detected. Phase loss must be detected, which requires a more accurate conversion circuit and transformer.

An object of the present invention is to provide an open phase detection circuit that can reliably detect an open phase of a multiphase AC input power source even when the input voltage of the multiphase AC input power source is switched.

[Means for Solving the Problems] FIG. 1 shows a block diagram of the principle of the present invention. As shown in this figure, the present invention includes a phase voltage detection circuit 2□ (i is 1-m, representing the number of phases) for each phase that detects the phase voltage of a polyphase AC input power supply, and a polyphase AC input power supply. The outputs of the reference voltage generation circuit 4, which generates a reference voltage proportional to the input voltage of the input power supply, and the phase voltage detection circuit 2 are compared with the output of the reference voltage generation circuit 4, and the output of the former is equal to the output of the latter. An open phase detection circuit for each phase that outputs an open phase detection signal when the drop is lower than 6. This configuration constitutes an open phase detection circuit having the following.

[For production]

Even if the input voltage of the multiphase AC input power supply is switched, the reference voltage proportional to the switched input voltage value is output from the reference voltage generation circuit, so the phase voltage of the multiphase AC input power supply and the reference voltage can be compared. This makes it possible to reliably detect phase loss in a multiphase AC input power source.

〔Example〕

In FIG. 2, a resistor R2 is connected to the three-phase AC input power line L1 via a diode D1 and a resistor R1.
A resistor R4 is connected to the phase AC input power line L2 through a diode D2 and a resistor R3, and a resistor R6 is connected to the three-phase AC input power line L3 through a diode D3 and a resistor R5.

Smoothing capacitors CI and C2iC3 are connected in parallel to each of the resistors R2iR4 and R6, respectively.

Diode DI, D2. D3 is the input power line Ll.

It is for half-wave rectification of the phase voltage of R2iR3,
This half-wave rectified voltage is applied to resistors R1, R2, resistor R3,
The voltage is divided by R4 and resistors R5 and R6, respectively. The divided voltage vl applied across the resistors R2iR4 and R6 is detected as the phase voltage of the input power lines Ll, L2, and R3, respectively. That is, diodes DI, D2. D3, resistance R1-
R6 and capacitors CI and C2iC3 are connected to the phase voltage detection circuit 2 for each phase in FIG. It consists of And each detection voltage ■1 is the positive voltage (+) of the comparator circuits 20, 21, 22.
is input as the detection voltage.

The configuration is such that a reference voltage v2 from a reference voltage generation circuit, which will be described later, is applied to each negative voltage (-). Each comparator circuit 20, 21, 22 compares the detection voltage Vl with the reference voltage 2, and outputs an open phase detection signal when the voltage vl is lower than the voltage v2. Detection circuit 6
．． It is configured as. In addition, input amount R lines Ll, L2
．． A DC stabilizing circuit 9 corresponding to output conditions is connected to L3 as a DC stabilizing power supply device.

In addition, input power lines Ll, L2. L3 includes a diode D7. which converts the three-phase AC voltage into DC voltage. D8, D9. D.I.
O, Di l, Di2, capacitor C4, C5, resistor R
A rectifying and smoothing circuit consisting of R13 and R14 is connected, and a ringing choke converter 23 is connected to this rectifying and smoothing circuit. The main parts of the ringing choke converter 23 in relation to the present invention include a transformer 24 and an NPN
Consisting of a transistor 25, a resistor R15, a diode D13, and a resistor R16, the output winding 24B of the transformer 24
A rectifier and smoothing circuit (not shown) is connected to the power supply, and is used as a DC power source for a small-capacity DC output circuit or various control circuits in the power supply device. A diode D15, a capacitor C7, and resistors R18 and R19 are also connected to the Heas drive winding 24A for switching drive of the transistor 25. The black circle attached to the transformer 24 represents the winding start side of the coil.

In the three-phase full-wave rectifying and smoothing circuit composed of diodes D7 to D12, capacitors C4 and C5, and resistors R13 and R14 that constitute the DC power supply of the ringing choke converter 23, the human power supply vAL1. Even if one phase among L2 and R3 is open, if there is no change in the input voltage value of the other phases that are not open, the circuit will operate as a single-phase full-wave rectifier and smoothing circuit, so its output voltage will not change. Furthermore, a pulse voltage proportional to the input voltage is always generated between the voltages P and Q of the base drive winding 24A of the ringing choke converter 23.

The reference voltage generation circuit generates a pulse voltage between voltages P and Q through a diode D15, a capacitor C7, and resistors R18 and R.
19, the voltage is rectified and smoothed, and the divided voltage (2) of the resistors R1B and R19 is obtained as a reference voltage proportional to the input voltage.

In the above configuration, the detection voltage Vl of each phase and the reference voltage ■
2 is compared by each comparison circuit 20, 21.22,
When the voltage Vl falls below the voltage ■2, each comparison circuit 2
An open phase detection signal is output from 0, 21, and 22. In this case, the reference voltage v2 will be a value proportional to the three-phase AC input power supply voltage, and even if the input voltage value is switched to multiple levels, a reference voltage value proportional to the input voltage value will be automatically set. , it is possible to reliably detect phase loss in a multiphase AC input power source. In addition, there is no need for a voltage switching circuit for switching the input voltage of the multiphase AC input power supply, a transformer for detecting open phase, etc., and it can be realized with a simple circuit configuration, reducing the space required for mounting components and reducing costs. It can contribute to the reduction. Furthermore, even if the input voltage value of the multiphase AC input power source fluctuates or changes in multiple stages, open phase of the multiphase AC input power source can be detected with high accuracy.

In this embodiment, the pulse voltage of the base drive winding 24A of the ringing choke converter 23, which is a relatively low voltage, is used as the power supply side of the reference voltage generation circuit, but the pulse voltage proportional to the input power supply voltage is used. The reference voltage generation circuit may be constructed from the DC output of a three-phase full-wave rectifying and smoothing circuit including diodes D7 to D12, capacitors C4 and C5, and resistors R13 and R14, as long as the circuit can obtain a DC voltage.

In this case, the DC output voltage of the three-phase full-wave rectifying and smoothing circuit is 3
For example, if the phase AC input power supply voltage is AC200V or AC400V
When switching V, it is about DC283V and about 5V, respectively.
66■, each comparator 20, 21 .
Since the reference voltage input to 22 is a few square meters, a large voltage dividing circuit using resistors and the like is required.

[Effects of the Invention] As explained above, according to the present invention, the value of the reference voltage is set to a value proportional to the input voltage of the multiphase AC input power supply, so that the input voltage value of the multiphase AC input power supply does not fluctuate. Alternatively, even if the change occurs in multiple stages, phase loss in the multiphase AC input power source can be reliably detected, contributing to improved reliability, cost reduction, and miniaturization of the device.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention, FIG. 2 is a diagram showing an embodiment of the present invention, and FIG. 3 is a configuration diagram of a conventional example. In Figures 1 and 2, 2! is the phase voltage detection circuit (diode D1, resistor R1, R
2. Capacitor C1: Diode D2, Resistance R3, R4
, capacitor C2: diode D3, resistors R5, R6,
capacitor C3), 4 is a reference voltage generation circuit (diode D7 D8D9 .
Dlo, Dll, D12. D13. D15, capacitor C4, C5, C7, NPN) transistor 25, resistor R13, R14, R15, R16゜RlB, R19,
), 6i is an open phase detection circuit (comparison circuits 20, 21, 22). 1st discharge p10 catty/return flow 771 force Figure 1

Claims (1)

[Claims] (1) Phase voltage detection circuit (2_i) for each phase that detects the phase voltage of a multiphase AC input power supply (i is 1 to m and represents the number of phases.)
, a reference voltage generation circuit (4) that generates a reference voltage proportional to the input voltage of the polyphase AC input power supply, and a phase voltage detection circuit (2_
It has an open phase detection circuit (6_i) for each phase that compares the output of i) and the output of the reference voltage generation circuit (4) and outputs a loss detection signal when the output of the former is lower than the output of the latter. An open phase detection circuit characterized by: