Research On The Sensorless Control Strategy For Small Pump Motor

It is of great significance for our country to realize energy saving and emission reduction,economic and social sustainable development by studying the energy saving ways and measures of water pump,improving the operation efficiency and reducing the energy consumption of the system.It is an inevitable trend for the development of small pumps to select permanent magnet brushless motors as the driving system.In this paper,a small pump motor is taken as the object,and the sensorless control strategy of permanent magnet brushless motor is studied by means of the terminal voltage detection and sliding mode variable structure control.First of all,combined with the sensorless control principle of the back-EMF detection method,the simulation module of algorithm is established on Matlab/Simulink based on the mathematical model of the burshless dc motor;then a simulation model consisted of the speed and current dual-closed-loop is established based on a sliding mode observer according to the mathematical model of the permanent magnet synchronous motor.The simulation results showes that the two simulation models have strong anti disturbance ability and restrain the chattering effectively.The feasibility of the sensorless control strategy is demonstrated by the simulation results as well.Secondly,the hardware and software structure of the control system,the function principle and its implementation are studied based on the dsPIC33FJ32MC204 chip.The structure of control system is greatly simplified due to the use of intelligent power module in the hardware design.A digital filter is used to estimate the back EMF and zero crossing,which greatly improves the detection rate of BEMF-crossing-zero signals.The traditional sign function is replaced as a saturation function,used to weaken the chattering of the sliding mode control.Finally,according to the design scheme,the experimental platform of sensorless control for the small pump is built,and the rationality and correctness of the design scheme are verified by the experiments.The motor is started through the three-stage starting method.The experimental results showes that the stable operation of small pump without position sensor is achieved through the two sensorless control strategies,and the commutation time can be accurately detected by the back-EMF detect method,and the sliding mode observer have high estimation accuracy of rotor angle.The starting performance of the motor is greatly improved by the changed starting mode of current PI loop.The dual closed-loop system of sine wave control without position sensor have stronger robustness and better anti disturbance effect on the load.