1.3.6 Control Overview
Perfect Harmony? is a simple “synchronous” control. Basic operation is summarized as follows:
? Control sends message to each power cell control via dedicated fiber links
? Cell executes request by firing one switch pair:
- Plus DC voltage
- Minus DC voltage
- Zero voltage
? Cell control confirms switch pair fired
? Control confirms firing from:
- Output voltage divider
- Output Hall Effect current transducer
? No two cells ever switch at the same time
? Cell switching rate is low compared to effective switching frequency of VFD:
- Typically 600 Hz carrier frequency per pole, results in 1200 Hz switching frequency per cell
? VFD effective switching frequency is simply the cell switching frequency times the number of cells per
phase
? Switching rate is constant over the entire output frequency range
? Default control is an open flux vector control:
- V/Hz and closed loop (encoder) control modes also available

矢量 应该没压力，默认开环矢量， 也可以V/F 和 闭环编码器