回转式空气预热器变频-工频同步切换控制器

VF-FF synchronous switchover controller for revolving air preheater

大容量回转式空气预热器在变频-工频切换瞬间,常因电源相位不一致引发过电流冲击而导致切换失败。为有效解决这一问题,开发了基于锁相环技术的变频-工频同步切换控制装置。将变频器作为压控振荡器(VCO);采用高性能的C8051F单片机作为主控制器,通过其内部集成的高速AD、DA转换器采集变频、工频电压信号,利用软件锁相技术,经数字运算进行鉴相和锁相控制,实现变频与工频之间的相位锁定。实际运行证明,该同步切换装置锁相快速、准确,稳态相位误差小于±7,°切换电流小于1.5倍电机额定值,实现了空气预热器变频-工频的无扰切换。

At the switchover moment of high-power revolving air preheater from VF（Variable Frequency） to FF（Fundamental Frequency）,the large impact current caused by their inconsistent phases may result in switchover failure. A VF- FF synchronous switchover device based on the PLL （Phase- Locked Loop） technology has been designed for it. The device takes the inverter as VCO （Voltage-Controlled Oscillator） , the high performance single-chip C8051F integrated with high-speed AD and DA converters as the main controller. It samples voltage signals of VF and FF sources and realizes phase-locked control by software phase-detecting and phase-locking operations. Experiment results show that the device can lock phase quickly and accurately,its steady phase error is within ±7° and switching current is below 1.5 times of motor rated current. The device realizes bumpless switchover for air preheater from VF to FF supply source.