| 摘要 |
Two apparatuses are disclosed for controlling the speed of an AC synchronous motor-pump utilizing a series of stepped voltage pulses at the driving frequency. The first apparatus is an isolated variable frequency drive comprising step-down transformer 100 , full wave rectifier and filter 101 , micro-controller 108 , driving-voltage array generator 102 , gate driver 107 , inverter bridge 103 and step-up transformer 104 . The second apparatus is a non-isolated high voltage variable frequency drive comprising full wave rectifier and filter 201 , low voltage, dual output power supply 205 , micro-controller 208 , driving-voltage array generator 202 , gate driver 207 and inverter bridge 203 . Methods are given to determine voltage array values and pulse times to generate a stepped voltage approximation of a sine wave driving waveform.
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