离散随机SVPWM中概率密度函数的表征与选择

Characterization and selection of probability density function in discrete random SVPWM technology

针对连续随机空间矢量脉宽调制(space vector pulse width modulation, SVPWM)技术在永磁同步电机驱动系统中对高度集中的PWM谐波能量分散效果不理想问题,提出一种基于Beta分布的离散混合双随机SVPWM技术。首先,基于调制理论分析传统SVPWM技术的开关函数与电压PWM谐波之间的内在联系,并根据开关函数中调制参数的组合形式不同对随机SVPWM技术进行分类。然后,从预定义的离散序列中随机选择开关频率因子和脉冲位置因子以实现开关函数中开关频率和脉冲位置的离散随机化,同时基于Beta分布和均匀分布对离散随机序列进行优化,以改善离散随机SVPWM技术的PWM谐波抑制效果,使得频域中的谐波能量分散到更多频率分量处。通过实验平台测试,结果显示基于Beta分布的离散双随机调制技术相较于传统随机脉宽调制技术谐波峰值降低了53%,表明引入Beta分布的离散混合双随机SVPWM技术具有更优的谐波散射效果,同时还具有与传统SVPWM技术相当的驱动效率。

Aiming at the problem that the continuous random spatial pulse width modulation(SVPWM)technology is not ideal for the highly concentrated PWM harmonic energy dispersion effect in the drive system of permanent magnet synchronous motor,a discrete hybrid dual random(DHRC)SVPWM technology based on Beta distribution is proposed.Firstly,based on modulation theory,the intrinsic relationship between the switching function and the voltage PWM harmonics of the traditional SVPWM technology is analyzed,and the random SVPWM technology is classified according to the combination of modulation parameters in the switching function.Then,the switching frequency factor and pulse position factor are randomly selected from the predefined discrete sequence to realize the discrete randomization of the switching frequency and pulse position in the switching function,and the discrete random sequence is optimized based on the Beta distribution and uniform distribution to improve the PWM harmonic suppression effect of the discrete random SVPWM technology so that the harmonic energy in the frequency domain is dispersed to more frequency components.Through experimental platform testing,the results show that the discrete dual random modulation technology based on Beta distribution reduces the harmonic peak by 53%compared with the traditional random pulse width modulation technology,indicating that the DHRC-SVPWM technology introduced with Beta distribution has better harmonic scattering effect and has the driving efficiency comparable to the traditional SVPWM technology.