电压空间矢量控制稀土永磁同步电动机变频调速研究

On Controlling REPMSM Speed with Voltage Space Vector

提出一种多边形磁链轨迹作图法；导出周期开关状态表；用变频定宽调制法进行电压、频率同步平滑调节；由８０３１单片机实现电压空间矢量顺序控制；最后推出ＰＷＭ线电压谐波计算公式及相应数据．

Numerous studies are now available in China on PWM speed adjustment through varying frequency, whose adjustment, in turn, is baSed on the method of voltage space vector.But, all of them still suffer from five main shortcomings (most of them rather serious ): (1)insuffieient symmetry of both nux track and line voltage phase ; (2) direct obtaining ofswitch state table not possible; (3) poor dynamic characteristics; (4) high frequency requirements on REPMSM not satisfied 4 (5) cost of modulator too high. We now present agraphical method that can eliminate much of the above main shortcomings.Our graphical method is easily derivable from the analytical method of Japanese scholars[1,2]. We construct relatively easily Figs. 1 and 2. In Fig. 2 (a) and (b), the flux tracksare both very nearly circular in shape (referring to the envelope curves of the tooth- shapedbroken lines ). When tracks are very nearly circular, main shortcomings (1) and (2) aremuch reduced.We reduce main shortcoming (3) by employing a recently developed technique. Thistechnique can reduce significantly the amplitudes of harmonics (Table 2).Finally we employ well known MCS51 device, which, together with reduction in shortcomings (3) through (5), can bring down the cost by as much as about 75% under P. R. C.conditions. With the aid of harmonic analySis, we find that harmonic content is controlled tobe about less than 7% , and is not influenced by change of duty ratio'