Digital control of high frequency PWM converters

A method is presented for the digital control of high frequency PWM power converters. Digital current mode control uses samples of inductor current and output voltage to implement a control strategy in software. Average inductor current is calculated each switching cycle and compared to the current program level, providing true current mode control. This has several advantages over traditional methods. Components due to the up and down slopes of the inductor current waveform are not present in the current error signal. Current error amplifier gain is not, therefore, limited at the switching frequency in order to prevent subharmonic oscillation. Slope compensation is not required to stabilise the converter at duty ratios above 0.5 and there is no peak to average error introduced. A modular architecture is put forward for practical circuit implementation. Loop responses using the Texas Instruments TMS320C51 are discussed and features introduced by the use of digital control analysed