Current-controlled PWM strategy with carrier wave for constant switching frequency

The most common current-control methods uses hysteresis controllers. With these conventional controllers it is inherently impossible to achieve constant switching frequency and current-error minimization at the same time. A method to realize constant switching frequency is to add a triangular carrier wave with constant amplitude and frequency to the reference signal. The error between the obtained signal and current feedback determines the constant PWM switching logic. However, unwanted switching occurs. The paper proposes an improved current-controlled PWM strategy with carrier wave for constant switching frequency, which is easy to implement. Its mathematical expression and validation is illustrated by means of simulation. Also a comparison between the proposed current-controlled PWM strategy and the well-known voltage-controlled PWM procedure is made from point of view of harmonic distortion.