| 摘要 |
A power circuit for a precipitator utilizes a pair of silicon controlled rectifiers (SCR's) which are triggered by detecting the zero crossover of a power signal. The power transmitted through the SCR's is determined by the time period from the detection of the zero crossover to the generation of the trigger signal. Power signals are typically subject to noise which interferes with the detection of the zero crossover. Filters are provided for reducing the noise interference but function without altering the phase relation of the zero crossover of the filtered signal in respect to the unfiltered power signal. A pulse train of higher frequency than the power signal is generated to provide a plurality of triggering pulses for the SCR. Further, phase control signals are generated for each SCR to prevent the generation of trigger pulses when the SCR's are reverse biased. Thus, the present invention provides a precision voltage control for a power supply circuit which is particularly applicable for powering an electrostatic precipitator. |
