Design and Research of Brushless DC Motor for Water Pump

　　Design and Research of Brushless DC Motor for Water Pump
　　With the increasement of conflict of energy supplying, extending saving-energy technology of water pump system has important economic and social benefit. The development of permanent magnet electrical machinery with high efficiency and high power factor supply new ways for water pump saving energy. There are rich rare earth resources in our country, which have many advantages to develop variable frequency speed control system. Based on analysis the energy saving principle of water pump, permanent magnet brushless DC motor(BLDCM) is Cast Alnico Magnet employed into water pump system in this paper. Several parts are included:1、 A driver for BLDCM with 7.5kW is designed based on TMS320F240, the main circuit of driver and detail control circuit are given. System software and corresponding architectures are designed. In the control loop of speed and current, fuzzy PI switch control with conbination of traditional PI and fuzzy control is used in speed loop. Dynamic response of system is improved through simulation and experiment.2、 Electromagnetic design of BLDCM for pump is analyzed and design procedure is improved considering the influence of inductance on motor.3、 Basis on the analysis of system frame and running characteristic of BLDCM, optimization method for system efficiency is presented. Different PWM modulate modes are proposed to reduce the loss of http://www.chinamagnets.biz/Alnico/Cast-Alnico-Magnet.php driver and corresponding effects on motor are also analyzed. The influence of different commuting angles on motor efficiency is concluded and the optimal commuting angles is found.4、 The no-load electromotive force and load experiments of prototype are performed to validate design scheme and performance. Corresponding experiments of permanent magnet synchronous motor, induction motor and variable frequency induction motor are compared with BLDCM to testify validity of applying BLDCM into water pump saving energy.