对于三相异步电动机,离散变频是一种新颖的能有效提高电机起动转矩的新型控制方法,但其存在电磁转矩脉动严重和电流有效有效值较大的缺点.为克服该缺点,首先从定子空间电压矢量分析基于周波控制的离散变频工作过程,明确定子电压矢量的重复触发是该离散变频产生电磁转矩脉动的原因.然后利用六边形空间电压矢量原理提出基于空间电压矢量的离散变频控制方法,将一个周期的电压矢量减小至6个,避免了电压矢量重复触发或反方向导通,以减少电磁转矩脉动.最后从定、转子电流和电磁转矩仿真对比两种离散变频起动过程,结果表明基于空间电压矢量的离散变频起动转矩更大、起动更加平稳,起动过程性能明显优于基于周波控制的离散变频.%For three-phase asynchronous motor,discrete frequency conversion is a novel control method which can ef fectively improve the starting torque of the motor.But it has serious electromagnetic torque ripple and large current effective value.To solve the problems,firstly,form the stator space voltage vector,the working process of discrete frequency conversion based on the cycle control was analyzed,the ripple reason was repeat trigger of stator space voltage vector.Secondly,utilizing the principle of hexagonal space voltage vector,the control method of discrete frequency conversion based on space voltage vector was proposed.The voltage vectors in a cycle are decreased to six,the repeat trigger or reverse conduction was avoided,the electromagnetic torque ripple was decreased.Lastly,through simulation and experiments,from the current and electromagnetic torque of stator and rotor,the start process of two discrete frequency conversions were contrasted.The results indicate that the start torque of discrete frequency conversion based on the space voltage vector is larger,the start process is more stable,the performance is better than discrete frequency conversion based on the cycle control.
展开▼
