For the needs of the fast switch in three-phase emergency power supply which is from the utility power output to the inverter output, phase lock is the key technology of fast switching. The principle of space vector pulse width modulation(SVPWM) and asynchronous frequency modulation is expounded. SVPWM method with the characters of digital simple realization, high DC utilization, and the asynchronous frequency modulation algorithm is also simple and has high efficiency. According to the principle,the inverter output control algorithm and digital phase lock algorithm for three-phase inverter emergency power is designed ,and the specific software realization process is given. The hardware platform is established which is constituted with step-down zero detection circuit, TMS320LF2407A control circuit, isolation drive circuit and three-phase bridge inverter circuits. The reliability and the effectiveness of this approach,and the waveform's three-phase steadily output of space vector pulse width are clearly demonstrate through the emulation and actual test result.%针对三相逆变应急电源从市电输出到逆变输出的快速切换要求,快速切换实现的关键是锁相.这里阐述了空间矢量脉宽调制(SVPWM)、异步变频调制的原理,SVPWM方法具有数字化实现简单、直流利用率高等特点,异步变频调制具有算法简单、效率高的特点.根据原理设计了适合三相逆变应急电源的SVPWM逆变输出的控制算法和数字锁相算法,并给出了具体的软件实现流程.建立了由降压过零检测电路、TMS320LF2407A控制电路、隔离驱动电路和三相全桥逆变电路构成的硬件平台.实验结果表明:设计的软件算法可以实现可靠、有效、高精度的锁相,空间矢量脉宽波形的三相输出稳定.
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