Design On BLDCM Controller In Automotive Air-conditioning

Brushless DC motor (BLDCM) draws more and more attention in many areas because of its excellent reliabilities and high efficiencies, especially in high performance and high precision control fields. Brushless DC Motor with excellent performance as evaporating fan of automotive air-conditioning can improve reliability and service life of the fan. Brushless DC motor in automotive air-conditioning is usually controlled without position sensor. A drawback of sensorless brushless DC motor is torque ripple, which triggers the vibration of evaporating fan. The vibration is the root of vehicle noise that harms the comfortable environment.To solve this problem and combined with automotive air conditioning brushless DC motor characteristics, the current prediction method is used to suppress commutation torque ripple of sensorless brushless DC motor. The mathematical model and the working principle are described in chapter two. The back-EMF zero crossing method and commutation angle delay are used to detect rotor position accurately. The increase rate and decrease rate of commutation current are associated with PWM modulation, by analyzing the influence on torque ripple using five different PWM modulations, the PWM_ON modulation causes minimum torque ripple. To reduce the commutation torque ripple, the commutation current is adjusted by commutation current prediction control. Simulation results show that the method is effective and feasible.The design on control system of brushless DC motor in automotive air-conditioning is introduced in detail, which contains the constitution of hardware, driver and inverter circuit, detection circuit, and serial communication circuit. A control system experimental platform based on TMS320F2812 is designed for experimental use. The validities of the anticipatory method are strongly supported by the experimental results.