基于电流谐波最小的永磁同步电机无差拍预测电流控制

Deadbeat predictive current control of permanent magnetsynchronous motor with current harmonics minimization

基于空间矢量调制(SVM)的无差拍预测电流控制(DBPCC)具有原理简单、动态响应快、开关频率固定等优点,在永磁电机高性能控制中得到了广泛应用。但是传统的无差拍预测电流控制采用单一的7段式矢量序列,在高速重载等高调制比工况下电流谐波相对较大。已有研究表明,高调制比时采用母线钳位空间矢量调制能获得更小的电流谐波,但优化矢量序列的选择比较复杂且仅在开环运行下进行验证。在解析推导基于4种电压矢量序列的空间矢量调制的电流谐波基础上,提出了一种变序列SVM无差拍预测电流控制策略。该策略根据调制比在线选择使电流谐波最小的优化电压矢量序列,不仅计算量小,而且有效降低了电流谐波。仿真和实验结果表明,相比基于单一矢量序列的传统无差拍预测电流控制,所提出的方法在全调制比下都可以获得最小的电流谐波和THD。在调制比大于0.92时,电流THD可减小30%以上。

Deadbeat predictive current control(DBPCC)based on space vector modulation(SVM)has been widely used in the high-performance control of permanent magnet synchronous motor drives,due to its simple principle,fast dynamic response and fixed switching frequency.However,the conventional DBPCC adopts a single 7-segment vector sequence,which results in relatively large current harmonics at high modulation indices such as high speed and heavy load.The prior studies have proved that the current harmonics of bus-clamping space vector pulse width modulation are smaller at high modulation indexes,but the choice of optimal vector sequence is complex and it is only verified under the conditions of open-loop operation.After deriving the analytical expressions for the current harmonics of four voltage vector sequences,this paper proposes a variable-sequence-SVM DBPCC.According to the modulation index,this method online selected the optimal voltage vector sequence with minimal current harmonics,which is simple and effectively reduces the current harmonics.Simulation and experimental results confirm that, compared to conventional DBPCC based on the fixed vector sequence, the current harmonicsand total harmonic distortion (THD) of the proposed method are minimized at full modulation indices.The current THD can be reduced by more than 30% when the modulation index is above 0. 92.