INFLUENCE OF THE MODULATION METHOD ON THE CONDUCTION AND SWITCHING LOSSES OF A PWM CONVERTER SYSTEM
INFLUENCE OF THE MODULATION METHOD ON THE CONDUCTION AND SWITCHING LOSSES OF A PWM CONVERTER SYSTEM
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DOI：
10.1109/28.108456
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发表时间：
1991-11-01
影响因子：
4.4
通讯作者：
ZACH, FC
中科院分区：
文献类型：
--
作者：
KOLAR, JW;ERTL, H;ZACH, FC
三相脉宽调制（PWM）转换器系统的调制方法的优化通常不会导致纯正弦相位调制函数。与电动阀的输出电流和正向特性相关，这些相位调制函数直接限定了电力电子器件的传导损耗。本文探讨了高脉冲频率PWM变换器系统桥臂的导通损耗对相位调制函数形状的依赖性。这是针对针对最小谐波电流均方根值进行优化的调制方法而完成的。将结果与简单正弦调制获得的结果进行比较。除导通损耗外，还计算了电动阀的开关损耗。这里，仅对于输出电压通过仅两个有源桥臂和第三个非开关桥臂的周期性变化形成的调制方法，才获得与经典正弦调制的偏差。如计算所示。这些调制方法允许有效开关频率的显著增加。这种效果取决于变换器输出相电压的基波和变换器输出相电流之间的相位角;对于这种比较，假设与简单正弦调制的开关损耗相等。本文讨论了PWM变换器系统脉冲频率的最佳调制问题。必须观察的一个附带条件是，开关功率损耗必须对应于在恒定脉冲频率下操作时发生的功率损耗。计算的最佳调制导致在上调制区域中的谐波功率损耗的减少。此外，由于频率调制，与具有恒定脉冲频率的操作相比，频谱扩展到更宽的频带;在那里，频谱集中到脉冲频率的倍数附近的谐波。 例如，这种效应会影响由转换器供电的电机的噪声产生。
The optimization of the modulation method of a three-phase pulse-width modulation (PWM) converter system generally does not lead to purely sinusoidal phase modulation functions. In connection with the output currents and the forward characteristics of the electric valves, these phase modulation functions directly define the conduction losses of the power electronic devices. This paper explores the dependency of the conduction losses of a bridge leg of a PWM converter system with a high pulse rate on the shape of the phase modulation functions. This is done for modulation methods that are optimized with respect to minimum harmonic current rms values. The results are compared with the results gained for simple sinusoidal modulation. Besides conduction losses, the switching losses of the electric valves are calculated. Deviations from the classical sinusoidal modulation here are obtained only for modulation methods for which the output voltage is formed by a cyclic change via only two active bridge legs and a third, unswitching bridge leg. As the calculations show. these modulation methods allow a significant increase of the effective switching frequency, This effect is dependent on the phase angle between the fundamental of the converter output phase voltage and the converter output phase current; for this comparison, equal switching losses as for the simple sinusoidal modulation are assumed. The optimal modulation of the pulse frequency of a PWM converter system is treated. A side condition that has to be observed is that the switching power loss has to correspond to the power loss occurring for operation with constant pulse frequency. The optimal modulation as calculated leads to a reduction of the harmonic power loss in the upper modulation region. Furthermore, due to the frequency modulation, the spectrum is spread out to a wider frequency band as compared with the operation with constant pulse frequency; there, the spectrum is concentrated to harmonics in the vicinity of multiples of the pulse frequency. This effect can influence the noise generation of a motor supplied by a converter, for example.