Patent ID: 6819090
Filing Date: 2004-11-16
Classification: G05F

Abstract:
A circuit for regulating the voltage across a load connected to an ac power source, the circuit comprising:a switching means connected in series with the load, the ac power source connected between the series combination of the switching means and the load; a control means for controlling the phase angle at which the switching means permits application of the voltage from the ac power source across the load; a transformer, the primary of the transformer connected across the load, the ac voltage across the secondary of the transformer being proportional to the voltage across the load; a rectifier means for converting the ac voltage across the secondary of the transformer into a dc rectified voltage; a root mean square filter, the dc rectified voltage connected to the input of the root mean square filter to produce a dc filter output voltage proportional to the ac root mean square voltage across the load; a means for providing a setpoint voltage for the ac root mean square voltage across the load; and a means for comparing the setpoint voltage with the dc filter output voltage, whereby if the setpoint voltage is greater than the dc filter output voltage the control means adjusts the phase angle at which the switching means permits application of the voltage from the ac power source across the load to increase the effective voltage applied to the load from the ac power source, and if the setpoint signal is less than the dc filter output voltage the control means adjusts the phase angle at which the switching means permits application of the voltage from the ac power source across the load to decrease the effective voltage applied to the load from the ac power source, to regulate the voltage across the load as the voltage of the ac power source varies.