초록 ▼

An operating circuit for a semiconductor switch device of the type that passes electrical current from a source to an electrical load by forward biasing of the semiconductor\s control terminal includes a resistance bridge network having in an arm thereof the control terminal to one main terminal cir

An operating circuit for a semiconductor switch device of the type that passes electrical current from a source to an electrical load by forward biasing of the semiconductor\s control terminal includes a resistance bridge network having in an arm thereof the control terminal to one main terminal circuit of the semiconductor switch, and a bias control for alternately applying forward bias and reverse bias to the control terminal through the bridge network, whereby a voltage is developed across the bridge output during the interval in which the control terminal is reverse biased that is representative of the junction temperature within the semiconductor. The temperature representative voltage is observed, monitored, and used for indication and control. In a further embodiment the bias control operated periodically and includes inhibit means responsive to the derived temperature representative voltage exceeding a certain level, representative of a temperature maximum, for retaining the control terminal of the semiconductor in the back biased condition, until the derived voltage reduces in level thereby protecting the semiconductor from thermal burn-out. In a welding control circuit presented herein the foregoing bias control is adapted in an intra-phase control circuit.

대표청구항 ▼

The method of determining the junction temperature of a semiconductor switch device of the type which conducts current between its first and second main terminals in a series currentconducting path, including an electrical source and a load, responsive to the control terminal thereof being forward b

The method of determining the junction temperature of a semiconductor switch device of the type which conducts current between its first and second main terminals in a series currentconducting path, including an electrical source and a load, responsive to the control terminal thereof being forward biased relative to said first main terminal in a circuit including: first bias means for applying an forward bias voltage through a first resistor means to said control terminal; and second and third resistor means connected between said bias means and said first terminal; and a source of current and an electrical load connected in series circuit connected across said main terminals of said semiconductor switch device, comprising the steps of: interrupting said first bias means and substituting therefor a second bias means for applying a reverse bias voltage; and measuring the voltage between said control terminal and a circuit juncture between said second and third resistor means.