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Instantaneous detection circuitry ascertaining zero crossover point of current converter - uses rectifying bridge on sec. side with voltage at load branch used as measure for actual value of current
Instantaneous detection circuitry ascertaining zero crossover point of current converter - uses rectifying bridge on sec. side with voltage at load branch used as measure for actual value of current
The circuitry determining the instant of current-zero during the switching, e.g. by thyristors, of mains power rectifiers employs a transformer (W) whose secondary is connected to a bridge rectifier (D) and a border resistor (RB) wherein the volts drop is a measure of the primary current. A capacitor (C) is connected across the secondary to provide a short path for the secondary current during the demagnetisation of the transformer (W) core at a primary current-zero. The valve of the capacitor (C) is chosen such that its charged voltage at current-zero is less than the rectifier (D) threshold voltage. USE/ADVANTAGE - Provides accurate determination of primary current and its instant of zero which is not subject to time-lag caused by magnetising energy decay. Enables precise switching control of power rectifiers connected to mains network.
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