A motor controller includes a power constant controller configured to receive a target power of a permanent magnet synchronous motor (PMSM) and generate a first target speed based on the target power; a first signal generator configured to generate a second target speed; a speed constant controller switchably coupled to the power constant controller and the first signal generator, where the speed constant controller is configured to switchably receive the first target speed and the second target speed, and regulate a motor speed of the PMSM based on the received first target speed or the received second target speed; a first switch configured to switchably couple the speed constant controller to the power constant controller to receive the first target speed or the second target speed; and a first switch controller configured to control a switching state of the first switch based on the motor speed of the PMSM.