| Brushless DC motor(BLDCM)is widely used in electric vehicles,industrial control and aerospace due to its high power density,compact size and simple structure.In many applications,the battery is used as main power supply,but there are some shortcomings of battery,such as low power density,limited life-cycle and so on.For this reason,some scholars have proposed the method of applying supercapacitor/battery hybrid energy storage unit(HESU).In the drive system with BLDCM,the motor torque is the key index to measure the system performance.In this paper,a novel supercapacitor/battery hybrid energy storage unit(HESU)is designed,which includes supercapacitor,battery and MOSFET,without additional inductance.Three output modes of the hybrid energy storage unit are analyzed.The BLDCM and proposed HESU and are regarded as a whole system,and the effect of each switching vector is analyzed.Then,switching vector combinations that suitable for different operation states of BLDCM is designed.Furthermore,a control strategy of BLDCM is proposed.The main functions of this strategy include three aspects.In braking process,the strategy can use supercapacitor to store the energy regenerated from motor,thus improving the energy utilization.In acceleration process,the supercapacitor is used to assist the battery to power the motor,so as to avoid the influence of excessive output current on the battery life;In constant speed operation,the proposed HESU can achieve high voltage output through series batteries and supercapacitors during commutation period of BLDCM,thus suppressing the commutation torque ripple of BLDCM.Finally,the experimental platform is built and the proposed operation control strategy is verified experimentally.Through the analysis of the experimental results under the conditions of acceleration process,braking process and constant speed operation,the correctness of the theoretical analysis and the feasibility of the proposed strategy are verified. |
PDF Full Text Request