Patent ID: 7231266

Claim:
A sinusoidal wave follow-up digital control device for use with PWM inverters for tracking a sine wave, said digital control device comprising a compensator, a control object to be controlled by the sinusoidal wave follow-up digital control device and a feedback gain control, wherein the compensator is configured to receive as its input a signal obtained by subtracting a control quantity from a reference value; wherein the control object is configured to receive as its input a signal obtained by subtracting an output of the feedback gain control from an output of the compensator; and wherein a transfer function of the compensator is (k 2 z+k 1 )/(z 2 −2z cos ωT+12), where ω is an angular frequency, T is a sampling period, z is a z operator, and k 1 and k 2 are constants, thereby configuring a second-order compensator for providing high accuracy tracking of a sinusoidal reference waveform.