Research On Key Technology Of Feedback Energy Regenerated By BLDCM In Braking State

The Brushless Direct Current Motor not only has low power consumption,long service life,but also has the characteristics of small size and high reliability,and is widely used in various fields.When the motor is in the braking power generation state,the regenerative energy is transmitted to the DC-side filter capacitors of the DC-bus,generating a pump-up voltage which threatens the normal operation of the system.The traditional way is add a resistor on the DC side,which not only reduces the reliability of the device,but also wastes a lot of power.The generation of feedback energy regenerated by BLDCM in braking state solves this problem by reasonably recovering pump power.A energy feedback control system of Brushless Direct Current Motor is designed based on the structure of three-phase voltage type PWM rectifier in this paper.Firstly,the four-quadrant operation mode of PWM rectifier is analyzed.When the PWM rectifier is operated in the active inverter state,the energy feedback from the DC side to the AC source is realized.The voltage and current double closed-loop control strategy and SVPWM modulation mode are determined.Then aiming at the problem of current feedback harmonics of energy feedback device,an LCL filter is designed.The constraints of parameter selection are analyzed from the aspects of resonance frequency,total inductance,damping resistance and harmonic suppression ability.A set of effective test parameters is designed.Then the rationality of the system control strategy is verified by Simulink simulation platform.Based on this,a simulated low-voltage power grid was designed.Power stage and control circuit of the energy feedback device are selected and designed.With TI's TMS320F2812 as the core,the hardware and software part of the energy feedback device was completed.Finally,the experimental application of the energy feedback device was carried out on the experimental platform.By observing the experimental waveform of the energy feedback device,it is shown that the brushless DC motor energy feedback device designed in this paper can feed the braking energy of the motor back to the grid,which verifies the feasibility of the device design.