Model Reference Adaptive Control of Pulse Amplitude Modulated PM Motor Drive for High Power Transport Drone Applications

For moving applications such as high power transport drones, the motor drive always requires high demanded power density and efficiency for better cursing range. To maximize power output under limited battery voltage (50V~100V), surface permanent magnet (PM) motor with low phase inductance is preferred because of the low back electromotive force (EMF) voltage. Under this effect, the motor speed and the power density can be maximized. However, low inductance PM motors result in considerable switching reflected current harmonics, leading to performance degradation on the brushless DC (BLDC) drive. To solve this issue, this paper improves the BLDC drive on low inductance PM motors by adding a front-end DC/DC converter for the DC bus regulation, e.g. pulse amplitude modulation (PAM). In order to maximize the overall dynamic response, a model reference adaptive control (MRAC) is proposed to regulate the DC bus voltage. According to experimental results, the proposed PAM drive with MRAC achieves the better performance than conventional BLDC between the current total harmonic distortion (THD) and the dynamic operation. This proposed drive is implemented in a 5kW surface PM motor in a high power transport drone.