APPARATUS AND METHODS FOR VARYING OUTPUT PWM CONTROL OF AN INVERTER

Apparatus and methods of providing digital varying output, such as sinusoidal, pulse width modulation, SPWM, control for an inverter comprising at least a first switch (S3) and a second switch (S1) are disclosed. The method comprising: generating a first binary control signal (PWM3A) at a system modulation frequency; generating a second binary control signal (PWM1A) at an M-times higher carrier frequency; wherein generating the second binary control signal comprises: providing a periodic counter having a K-times higher reset frequency; calculating M switch-off moments; determining for each, a corresponding switch-off counter value and a corresponding counter sequence value; storing each switch-off counter value in a respective memory location corresponding to the respective counter sequence and dummy values in the remaining memory locations; and sequentially and periodically transferring the contents of the memory locations to at least one PWM value register (620).