JP2000056844A - Power output monitoring circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To securely and speedily specify a transistor which breaks down by monitoring voltage on both ends of a resistor, displaying abnormality and outputting the result of a detector detecting the display as an alarm signal. SOLUTION: The series circuits of resistors 8 and LED 9 are connected to the connection points of transistors 1 and resistors 2. Terminals on an LED 9-side are collectively connected and they are inputted to an integrating circuit 13. A variable bias 10 is connected to the output circuit. Voltage on both ends of the resistor is set to be 0 V when current output is '0' and to be maxim at the maximum current value. The variable bias 10 is adjusted so that it is not lighted even if LED 9 is the maximum value and it is lighted when the transistor is short-circuited. The lighting of LED 9 is extracted from outside 7 with the output of a photocoupler and the like. Output stage abnormality is generated as an alarm signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a faulty part of an output stage circuit in which a plurality of transistors are connected in parallel to control the output of a large current, the output current is divided into the transistors, and the output current is combined at the output terminal. And a monitoring circuit for specifying the information reliably and in a short time.

[0002]

2. Description of the Related Art The present invention relates to a power supply for outputting a direct current, and is applied to a power supply for an electromagnet for mass separation.

FIG. 1 shows a principle diagram of a large current DC output power supply unit using a plurality of current control transistors. Reference numeral 5 denotes an input terminal to which a DC power supply before control is applied. This voltage is applied to a plurality of transistors 1 and resistors 2 in parallel.
This unit is connected to the output terminal 6 at the output stage. This current output is a combination of those that are almost equally divided into a plurality of transistors. In this circuit,
When a short-circuit fault occurs in a transistor, the current shunted to the transistor increases, and the current flowing to the other transistors decreases, but the entire current maintains the original value.

If this state continues, the current of the other sound shunt circuit increases by the amount corresponding to the decrease of the shunt circuit by one.
The stress applied to the transistor increases and the transistor is easily damaged. Due to such a relationship, the spread of the failure occurs, and eventually, the remaining transistor and the resistor are overheated, and the failed component is rapidly expanded. However, there is a drawback that circuit failure cannot be found until this stage.

[0005]

SUMMARY OF THE INVENTION It is an object of the present invention to reliably and quickly detect a short-circuit and a disconnection of a shunt-type output transistor and a resistor of a shunt type DC output by a plurality of parallel transistors, and to specify a damaged portion. is there.

[0006]

SUMMARY OF THE INVENTION In a power supply output circuit of a type in which a plurality of control transistors are connected in parallel and an output current is divided so as to be equivalent to each other, a current flowing through each of the plurality of divided transistors is detected. It monitors the voltage at both ends of the resistor and the voltage at both ends of the resistor, displays an abnormality, and outputs a result of a detector that detects that the display has occurred as an alarm signal.

[0007]

FIG. 2 shows an output stage circuit according to the present invention. The + and-terminals 5 are input terminals for DC voltage before control. The current output 6 is out +, out-. This figure shows a shunt circuit in which six transistors 2 are arranged in parallel. The series circuit of the resistor 8 and the LED 9 is connected to the connection point of the transistor 1 and the resistor 2 respectively, the terminals on the LED 9 side are collectively connected, input to the integration circuit 13, and the output circuit has a bias 10 (variable). Connect. The voltage at both ends of the resistor 2 is 0 when the current output is 0.
V, the maximum value is obtained at the maximum current value.
Is adjusted so that the LED 9 is not lit even when the LED 9 is at the maximum value and is lit when the transistor is short-circuited.

When one of the LEDs 9 is turned on, L
Since the ED 11 is also turned on, the ED 11 can be taken out from the outside 7 by a photocoupler output or the like, and an output stage abnormality can be generated by an alarm signal. When a large number of output stage transistors are used, a plurality of units 12 shown in FIG.
The defective unit can be specified by the alarm described above. Further, when the inside of the unit is viewed, the LED 9 is lit, so that the damaged transistor can be specified.

This is a transistor fault monitoring circuit which is added to its output stage transistor circuit of a power supply having a large current DC output and a plurality of parallel connected transistor control systems.

[0010]

According to the present invention, when a short-circuit fault occurs in an output transistor of a power supply device of a type in which a large current DC output is divided by a plurality of transistors and controlled, the faulty transistor can be reliably and quickly identified. Ripple can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a conventional power supply output monitoring circuit.

FIG. 2 is an explanatory diagram of a monitoring circuit of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Control transistor, 2 ... Control resistor, 3 ... Output current detecting element, 4 ... Output current setting circuit, 5 ... DC input terminal, 6 ... DC output terminal, 7 ... Alarm output terminal, 8 ... Resistor, 9, 11 ... LED, 10 ... variable bias, 12 ...
Unit including monitoring circuit, 13 ... integration circuit.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 2G036 BA37 CA06 CA08 CA10 5G053 AA03 BA02 DA02 DA03 EB04 FA07 5H410 CC02 DD02 EA10 EA32 EB16 EB37 FF05 FF25 LL05 LL13 LL14 LL19 5H430 BB01 BB13 BB12 EE17 FE13 LA19 LB02

Claims (1)

[Claims] 1. A power supply output circuit of a type in which a plurality of control transistors are connected in parallel and an output current is divided so as to be equivalent to each other, a resistor for detecting a current flowing through each of the plurality of divided transistors; A power output monitoring circuit characterized in that the voltage at both ends of the resistor is monitored, an abnormality is displayed, and a result of a detector for detecting that the display is output is output as an alarm signal. .