With the increasing demand for high-efficiency, compact, and low-cost motor control in the thermal management systems of new energy vehicles, the electric water pump as a core thermal management actuator is undergoing a technological evolution from brushed to brushless and from sensored to sensorless. This paper systematically proposes and implements a 650 W permanent magnet synchronous motor sensorless Field-oriented Control (FOC) system based on the Infineon TLE9877QX chip. This system provides a reusable, highly reliable technical paradigm for the electronic control of automotive actuators such as electric water pumps, and holds significant engineering reference value for the design of other similar controllers.