异步电机分级离散变频软启动器研究

Research on hierarchical discrete frequency soft starter of asynchronous motor

为了维持电动机起动电流较小的同时增大其起动转矩,在原有的离散变频原理基础上,对调压主电路、保护电路等方面进行了进一步研究,提出了一种改进的异步电机分级离散变频软启动方式。主调压电路采用全控型晶闸管GTO来代替传统的可控硅晶闸管,在电路保护方面,用理想型开关组取代传统的三相断路器,通过搭建MATLAB仿真模型和实物验证,并将仿真结果与实验结果做对比。分级离散变频软起动不仅能减小起动电流,还能有效地提高起动转矩,由二分频向工频过渡时,电流波动较小,过渡平滑,且相同时间内电动机转速也相对较高,在0~0.5s内起动转矩明显增大,最大可达900 N·m,为普通晶闸管离散变频软起动的2~3倍。通过计算并控制某一分频的最优相位角和作用时间,使之平稳过渡到下一分频,即可达到理想的软起动目的。

In order to maintain the small starting current and increase its starting torque,on the basis of the original discrete frequency principle,the main circuit and the protection circuit of the voltageregulating system were further studied. An improved asynchronous motor discrete frequency conversion soft start mode was proposed. In the proposed mode,the traditional thyristor is replaced by GTO in the main circuit,and in the protection circuit,the traditional three-phase circuit breaker is replaced by the ideal switch group. By building MATLAB simulation model and through physical verification,the simulation results were compared with the experimental ones. This improved soft startmode can not only reduce the starting current,but also increase the starting torque. When transiting from two-divided frequency to the power frequency,the current fluctuation is relatively small,and the transition is smooth; meanwhile,the motor speed is relatively high. The starting torque increases obviously during 0 ～ 0. 5 s,and the maximum can reach 900 N·M,which is 2 ～ 3 times the traditional one. By calculating and controlling the optimal phase angle and action time of a divided frequency,it can smoothly transit to the next divided frequency to achieve the ideal soft start.