For internal feedback motors, a control system is designed, in which a chopper circuit is developed for speed regulation based on the rectifier-inverter principle and corresponding formulas. The voltage control instructions in dq rotating reference frame are generated by changing the voltage in 3-phase static reference into 2-phase rotating reference with PARK transformation combined with the forward feedback decoupling control strategy. A unity power factor operation can be achieved by setting the current of the q axis(reactive current)to be 0. The SVPWM controller generates a driving signal according to the phase and amplitude of voltage and current stator as well as sampling control voltage. By controlling the IGBT on or off, the excess energy is delivered to the stator. The control system is simulated in MATLAB and the results show that with the decrease of duty ratio, the speed and active power reduce, and the reactive power remains zero, suggesting the internal feedback motor is subject to a higher power factor during speed regulating. Finally, the electric bill of a pumping station in Jiangsu Province is calculated when the internal feedback motors are used to drive the pumps for a year. It is shown that a ￥413 100 budget can be saved after the motors are used, causing significant economic benefits.
WANG Bingshu, ZHANG Xiaodong, GUO Xiaoyuan. Approximate mathematical modeling and simulation of cascade speed regulation of inner-feedback motor[J]. Journal of system simulation, 2010,22(2):537-541.(in Chinese)
LIU Zhiqi, HUANG Kui, ZHANG Xiaodong. The application analysis and technology features of cascade speed control system of inner feedback motor[J]. Instrumentation analysis monitoring, 2010(1):9-11.(in Chinese)
VALAN RAJKUMAR M, MANOHARAN P S. FPGA based multilevel cascaded inverters with SVPWM algorithm for photovoltaic system[J]. Solar energy, 2013,87:229-245.
SHEHADA A, BEIG A R. An improved CSI fed induction motor drive[J]. International journal of electrical power & energy systems, 2013,46:26-35.
CHARUMIT C, KINNARES V. Discontinuous SVPWM techniques of three-leg VSI-fed balanced two-phase loads for reduced switching losses and current ripple[J]. IEEE transactions on power electronics, 2015,30(4):2191-2204.
GABALLAH M M. Design and implementation of space vector PWM inverter based on a low cost microcontroller[J]. Arabian journal for science and engineering, 2013,38(11):3059-3070.
VASQUEZ J C, MASTROMAURO R A, GUERRERO J M, et al. Voltage support provided by a droop-controlled multifunctional inverter[J]. IEEE transactions on industrial electronics, 2009,56(11):4510-4519.
ZHAO Di, HARI V S S P K, NARAYANAN G, et al. Space-vector-based hybrid pulsewidth modulation techniques for reduced harmonic distortion and switching loss[J]. IEEE transactions on power electronics, 2010,25(3):760-774.
DAS S, NARAYANAN G, PANDEY M. Space-vector-based hybrid pulsewidth modulation techniques for a three-level inverter[J]. IEEE transactions on power electronics, 2014,29(9):4580-4591.
XIAO Xiangning, JIANG Xu, LIU Hao, et al. Study on the SVPWM algorithm of N-level inverter in the context of non-orthogonal coordinates[J]. Frontiers of electrical and electronic engineering in China, 2006,1(2):199-204.
BABAEI E, SABAHI M. Development of pulse width modulation technique for controlling inverters under balanced and unbalanced operations[J]. Arabian journal for science and engineering, 2014,39(4):2941-2951.
YAO Wei, CHEN Min, MATAS J, et al. Design and analysis of the droop control method for parallel inverters considering the impact of the complex impedance on the power sharing[J]. IEEE transactions on industrial electronics, 2011,58(2):576-588.