三次谐波注入原理

通用变频器及异步电机控制Copyright©2005DongLei.Allrightsreserved.2005,11,北京2005,11,11BeijingEmail:[e-mail]内容™异步电机VVVF控制原理™通用变频器应用™异步电机VVVF控制的DSP实现方法2005,11,11BeijingEmail:[e-mail]内容™异步电机VVVF控制原理™通用变频器应用™异步电机VVVF控制的DSP实现方法2005,11,11BeijingEmail:[e-mail]异步电机定子绕组鼠笼转子2005,11,11BeijingEmail:[e-mail]异步电机中的旋转磁场2005,11,11BeijingEmail:[e-mail]异步电机输出转矩与转速关系起动转矩输出转矩电机转速与同步速的百分比2005,11,11BeijingEmail:[e-mail]异步电机的四象限运行2005,11,11BeijingEmail:[e-mail]变压变频调速的基本原理三相异步电机定子每相电动势有效值为：mNgkNfEΦ=11144.4为了使磁通保持恒定需要：常值=1fEg2005,11,11BeijingEmail:[e-mail]恒压频比的控制特性1U1fNf1NU1无补偿带定子电压补偿常值=1fEg常值=11fU2005,11,11BeijingEmail:[e-mail]基频以上的弱磁控制1U1fNf1NU1mΦmΦ恒转矩控制弱磁控制（恒功率控制）2005,11,11BeijingEmail:[e-mail]恒压恒频时的异步电机机械特性smnn0sTe010TeTemaxTemax2005,11,11BeijingEmail:[e-mail]0n03n02n01nN1ω11ω12ω13ω131211N1ωωωω补偿定子压降后的特性恒压频比控制时变频调速的机械特性2005,11,11BeijingEmail:[e-mail]恒Eg/ω1控制时变频调速的机械特性eTOnN0n03n02n01nN1ω11ω12ω13ω131211N1ωωωωTemax2005,11,11BeijingEmail:[e-mail]几种电压－频率协调控制方式的特性比较0s10Te恒Er/ω1控制恒Eg/ω1控制恒Us/ω1控制abc2005,11,11BeijingEmail:[e-mail]基频以上变频调速的机械特性eTOnN0nc0nb0na0nN1ωa1ωb1ωc1ωb1ωa1ωN1ω恒功率调速2005,11,11BeijingEmail:[e-mail]内容™异步电机VVVF控制原理™通用变频器应用™异步电机VVVF控制的DSP实现方法2005,11,11BeijingEmail:[e-mail]风机变频调速节能基本原理QH风量01QA1H风门开度最大管阻特性曲线风门开度最大管阻特性曲线恒风速下风压－风量曲线恒风速下风压－风量曲线QH风量01Q2QAB1H2HQH风量01Q2QAB1H2H风量大小需要改变时风量大小需要改变时风门开度减小风门开度减小2005,11,11BeijingEmail:[e-mail]风量01QA1HQH风量01Q2QAB1H2H压风此时电机功率此时电机功率风量改变后电机功率风量改变后电机功率风机变频调速节能基本原理2005,11,11BeijingEmail:[e-mail]风量01Q2QABC1H2H3H1n2nQH风量01Q2QABC1H2H3H1n2n通过改变电机转速可以得到同样的风压通过改变电机转速可以得到同样的风压风机变频调速节能基本原理2005,11,11BeijingEmail:[e-mail]风量01Q2QABC1H2H3H1n2n压风通过改变电机转速使得电机功率明显降低通过改变电机转速使得电机功率明显降低风机变频调速节能基本原理2005,11,11BeijingEmail:[e-mail]除尘风机变频改造方案PID调节器变频器IMJC除尘风机电炉烟尘发光管光敏元件给定信号闭环控制方案闭环控制方案2005,11,11BeijingEmail:[e-mail]内容™异步电机VVVF控制原理™通用变频器应用™异步电机VVVF控制的DSP实现方法2005,11,11BeijingEmail:[e-mail]riveBottomGateDriveTopHalf-hbridge(oneofthree)DEADTIMEDEADTIMEVDCCom.2005,11,11BeijingEmail:[e-mail]三相逆变器VBusPWM1PWM4PWM2PWM3PWM5PWM6Three-phasePWMwaveformsandharmonicspectrum.2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMz正弦PWM，简称为SPWM，这种PWM的脉冲宽度按正弦规律变化，因此可以有效地抑制低次谐波，使电机工作在近似正弦的交变电压下，转矩脉动小，大大扩展了交流电机的调速范围z数字化PWM方法发展迅速，典型的有自然采样和规则采样PWM两种方法2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWM分类z谐波消去法z等面积法z采样法采样法z自然采样法z规则采样法对称规则采样法不对称规则采样法2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMz自然采样法rUabtUcωsintTpt1t2tofftofft'ontont'sTsTbTtbTtaTtaTtsoffsonsonsoff−=+=+=−=2222''2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMbTtbTtaTtaTtsoffsonsonsoff−=+=+=−=2222'')sin1(2)sin1(2)sin1(2)sin1(22'2'11tMTttMTttMTttMTtsoffsonsonsoffωωωω−=+=+=−=rU/UMc=调制比2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMrUabtUcωsintTpt1t2tofftofft'ontont'sTsT)]sin(sin21[221'ttMTttttononpωω++=+=2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMz对称规则采样法rUaatUcωsintTpt1tofftontont2/sT2/sTofft2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMz对称规则采样法rUaatUcωsintTpt1tofftontont2/sT2/sTofftaTtaTtsonsoff+=−=44)sin1(4)sin1(411tMTttMTtsonsoffωω+=−=2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMz采样点只与载波比N有关z采样点与调制比M无关z适合于计算机控制)sin1(2)sin1(211tMTtMTtstpωω+=+=2005,11,11BeijingEmail:[e-mail]正弦脉宽调制技术SPWMz仅可以作为通用VVVF控制方式z不适合于高性能控制方法z电压利用率低0.866Vdc2005,11,11BeijingEmail:[e-mail]-upTable100%PWMlimit0%PWMlimit3次谐波注入V1sinωot()+V3sin3ωot()V1sinωot+2π3⎛⎝⎜⎞⎠⎟+V3sin3ωot+2π()ABCV1sinωot+4π3⎛⎝⎜⎞⎠⎟+V3sin3ωot+4π()25502566sin932562sin32…=⎟⎠⎞⎜⎝⎛⎟⎠⎞⎜⎝⎛iiiππ2005,11,11BeijingEmail:[e-mail],AmplitudeMωmUdcpwma,b,cDSP56F80xsinelook-uptablepointercalculationMCPWMMCPWM3-phsinewavegenerationwith3rdharmonic2005,11,11BeijingEmail:[e-mail]三次谐波注入的机理02468101214-2.0-1.5-1.0-0.50.00.51.01.52.0VωUaUbUc02468101214-2.0-1.5-1.0-0.50.00.51.01.52.0Vω02468101214-2.0-1.5-1.0-0.50.00.51.01.52.0Vω02468101214-2.0-1.5-1.0-0.50.00.51.01.52.0Vω2005,11,11BeijingEmail:[e-mail]1T2T3T4T5T6TRABC三次谐波电压为零2005,11,11BeijingEmail:[e-mail]totoptransistorPWMtobottomtransistorActualloadvoltage(fori+)Actualloadvoltage(fori-)Duringdead-time,loadinductancedefinesvoltagetokeepinductivecurrentflowingthroughdiodes.i+i-V+V-V+V-感性负载引起的死区电压畸变2005,11,11BeijingEmail:[e-mail]tiononMotorVoltageandCurrentWaveformsCurrentwithCorrectionDisabled1/2horse3phasemotorPWMFrequency=7.3KHzDeadTime=3uSOutputω=1.7Hz.2ampspeak-to-peak12voltspeak-to-peakCurrentzerocrossingVoltagewithCorrectionDisabled2005,11,11BeijingEmail:[e-mail]PWMBottomPWMActualloadvoltageExample1.(i+condition)Example2.(i-condition)V+V-死区补偿2005,11,11BeijingEmail:[e-mail]1WaveformRegister2WaveformDesiredSinewaveCorrectionObtainedbyAlternatingBetweenPWMRegistersVoltageWaveform2005,11,11BeijingEmail:[e-mail]补偿结果CurrentwithCorrectionEnabled2ampspeak-to-peak12voltspeak-to-peakV