Digital and Analog Systems for Pulse Width Modulation with Variable Frequency

Pulse-width modulation (PWM) is widely used for control in power electronics. The most of power electronic circuits are controlled by PWM signals of various forms. PWM transform the information in the amplitude of a bounded input signal into the pulse width output signal. The frequency of the output signal is usually constant. In this paper the new pulse-width modulation system with frequency modulation (FM) changing is described. Such system can simultaneously transmit two independent information one as PWM and second by FM modulation. Abbreviation for such modulation in this paper is PWMFM. The modulation and demodulation of the PWMFM can be easily enabled by means of microcontroller or by analog circuits. Transmitter and receiver systems for PWMFM were constructed and measured. Results are presented in this work.