Closed loop power controller

A closed-loop system, having an input and an analog output, for controlling power comprising,

• means to sum a signal applied to the input with a signal derived from the analog output to produce a difference signal representative of the polarity of the difference between said input signal and said derived output signal,
• means for producing a digital signal representative of the polarity of said difference signal,
• at least two switching networks, said switching networks having high energy outputs and being responsive to said digital signals, to reduce the level of said difference signal in the frequency band of interest at the means for producing the said digital signals,
• a low-pass filter between said high energy outputs and the said analog output to attenuate high-frequency noise, and
• a low-pass filter at least of the third order in said closed loop to enhance the signal-to-noise ratio at said output of said closed-loop system, said low-pass filter at least of the third order modified to maintain loop stability.

A closed-loop system, having an input and an output, for controlling power comprising,

• means to sum a signal applied to the input with a signal derived from the output to produce a difference signal,
• means for generating a reference signal, comparison means for comparing said difference signal with said reference signal to produce a digital signal representative of the polarity difference between said difference signal and said reference signal,
• at least two switching networks, said switching networks having high energy outputs representative of said digital signal, to reduce the level of said difference signal in the frequency band of interest at the means for producing the said digital signal,
• a low-pass filter between said high energy outputs and said means for producing the said digital signal to attenuate high-frequency noise, and a low-pass filter of at least the third order in the closed loop to enhance the signal-to-noise ratio and modified to maintain loop stability.