VARIABLE-SPEED ELECTRIC DRIVE Russian patent published in 1996 - IPC

FIELD: electrical engineering; mechanisms operating in comprehensive range of speed control at high efficiency. SUBSTANCE: each phase winding of induction motor 1 has insulated coils whose number depends on number of supply phases connected to respective outputs of power amplifiers 13, 14; power leads of frequency changers 15, 16, 17 are connected in delta. Adder 30 newly introduced in phase-shifting assembly 23 has its first input connected to output of sweep generator 23 and second input, to reference input 37 of power amplifier, and its output is connected to input of comparator 27. Phase-current pulse frequency is offset towards higher-frequency region by implementing multiphase modulation and improved power characteristics due to reduced motor loss caused by nonsinusoidal waveform of phase currents. EFFECT: extended control range, reduced loss due to improved waveform of phase currents. 5 dwg