Power Injection Compensation for PSK Modulation in IPT Systems

Phase shift keying (PSK) is a modulation scheme which allows a single inductive link to achieve simultaneous wireless power and data transmission (SWPDT). However, the phase shift modulation may result in significant power reduction during the period where the link settles to a new steady state after each phase shift. In this paper, a power injection compensation method is developed to temporarily increase the duty cycle such that power transfer is controlled at the correct average level during PSK modulation. This paper presents a design method for power injection compensation based on an approximated transient model of IPT system. The design method is tested in an experimental converter operating a 1.0MHz. The experimental results show that for 90˚ phase modulation, the power injection control system increases the average load power from 72% to 98% of the unmodulated value. This is done without communication and compensation from the secondary side showing that the compensation technique can be implied to the primary converter to compensate for power transfer reduction during high modulation rates where feedback delays from the secondary limit performance.