信号延迟对SPWM变频器性能的影响

On Compensating for Time Delay Effects of SPWM Inverter

分析了ＳＰＷＭ信号开关延迟对变频器性能的影响，给出输出基波电压及谐波电压计算表达式，并讨论了电压调制系数及电机功率因数角对输出基波电压的影响；给出了转矩及转速脉动计算公式。实验结果表明，通过对ＳＰＷＭ信号开关延迟进行补偿，变频器输出基波电压提高，电流波形极大地改善，转矩及转速脉动减小。

SPWM(Sinusoidal Pulse -Width Modulation) inverter is increasingly widely used in P.R.China's machinery industry. To improve its performance for better economic efficiency,one thing that needs to be done is to compensate for time delay effects.What I mean by compensating for time-delay effects is that the parts of output voltages corresponding to low -order harmonics are almost completely suppressed.This compensation is accomplished through our specially designed circuit as shown in Fig. 5.Eq.(4)is used for computing output voltages of fundamental component(n =1)and significant low-order harmonics(n= 3,5,7).Our compensation can make B3,B5,and B7 in eq.(4)almost zero.A1(the total output voltage of fundamental component)in eq.(4) depends on voltage modulation ratio p and motor power angle Fig.3a shows the variations of A1 with μ for = 0°, 30°, 60°and 90°.Fig.5 shows that wave form after compensation (Fig. 5b) is also somewhat improved over that without compensation (Fig. 5a).