Inspecting transistors in an inverter circuit

Details Inspecting transistors in an inverter circuit Inspecting transistors in an inverter circuit

1996-03-04

1997-12-02

Wieder, Kenneth A.

Electricity: measuring and testing

Fault detecting in electric circuits and of electric components

Of individual circuit component or element

324537, G01R 3126

Patent

active

056940513

ABSTRACT:
A method and apparatus for inspecting a transistor in an inverter circuit includes turning on only the transistor of the inverter circuit. A predetermined collector current is supplied to the transistor until a transistor junction temperature reaches a predetermined temperature. The transistor is acceptable if a difference between a transistor collector-to-emitter voltage when the predetermined collector current is supplied and a transistor collector-to-emitter voltage when the junction temperature reaches the predetermined temperature falls within a preset range. Switching elements of the inverter circuit are controlled to supply a current through a resistor to charge an electrolytic capacitor of the inverter circuit. A voltage across the electrolytic capacitor during charging and a time period is measured from the beginning of charging until a time when a voltage across the electrolytic capacitor attains a predetermined voltage. An electrostatic capacitance of the electrolytic capacitor is determined based on the measured time period and a resistance value of the resistor. The electrolytic capacitor is discharged and a discharging voltage and current are measured. An equivalent series resistance of the electrolytic capacitor is determined based upon the voltage of the electrolytic capacitor at the beginning of discharge, the electrolytic capacitance and the measured discharge voltage and current.

REFERENCES:
patent: 2872644 (1959-02-01), Reich
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patent: 4243933 (1981-01-01), Rollman
patent: 4626952 (1986-12-01), Morikawa
patent: 5386189 (1995-01-01), Nishimura et al.
Brosch, "Falsch Ist Rasch Gemessen", Elektrotechnik vol. 73, No. 4 Apr. 2, 1991, pp. 62-70.

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