Control Loops Comparative Study Based on IR Thermal Imaging for Electrical Drives with BLDC PM Motors

The effects of choosing among different control strategy when electric drives with BLDC PM motors are involved, lead inevitably to different heat losses even if the error performances are accepted as similar. A comparative study based on unconventional infrared thermal imaging is proposed to evaluate heat losses. Two cases are considered for medium power BLDC PM speed control. First control structure revises the classic P control loop and its practical implementation advantages. The second control algorithm present a modified PID control derived from state space approach. Thermal infrared captures are externally made, at the housing level of the BLDC PM motor. When using current and speed feedback, the captured external temperature results higher, in comparison to the case when using only speed as correction signal. A trade off must be established between torque requirements, heat losses and tracking reference signal.