Zero-Additional-Hardware Power Line Communication for DC-DC Converters

A power line communication (PLC) solution to provide a data link between two or more dc-dc power converters is proposed. The approach does not require additional analog circuitry or high-sample-rate analog-to-digital converters to be added on top of the original system. A modulation and signal injection method for the transmitter, and a sampling and demodulation strategy for the receiver are developed. The PLC frequency band is placed between the control loop cutoff frequency and the power electronics circuit cutoff frequency, in a region that we identify as the "intermediate frequency band". The transmitter modulates the converter voltage or current output by injecting perturbations into the control loop at the input to the PWM unit. To tolerate unsynchronized transmitter and receiver clocks, a virtual zero-crossing location algorithm is combined with long/short pulse identification to achieve demodulation at the receiver. The solution is verified experimentally and achieves reliable bidirectional PLC communication at 2 kb/s with an 8 kHz receiver sampling frequency.