Patent ID: 7956694

Claim:
A system for recovering the phase and amplitude of an AC power line signal comprising: (a) a phase detector having an output linearly proportional to phase error and independent of line voltage and further comprising (i) a quadrature demodulator ( 300 ) having a digital in-phase (I) channel ( 320 ) and a quadrature (Q) channel ( 330 ), (ii) an I-leg low pass filter ( 322 ), (iii) a Q-leg low pass filter ( 332 ), and (iv) a rectangular to polar converter ( 341 ); (b) a digital loop filter ( 342 ); and (c) a controllable digital oscillator ( 343 ) configured to produce in phase and quadrature reference signals for the quadrature demodulator; wherein (d) the quadrature demodulator, the I-leg low pass filter, and the Q-leg low pass filters are each implemented as analog elements; (e) the rectangular to polar converter, the digital loop filter, and the controllable oscillator are each realized as functions of a programmable microcontroller ( 800 ); (f) the microcontroller is adapted to produce at least one phase angle fired signal for controlling power delivered to a load.