| 摘要 |
Motor drive apparatus brings the actual speed (n) of an induction motor (4) into coincidence with a command speed (nc) by varying the frequency and effective value of a three-phase AC voltage (VWU, VUV, VVW) applied to the induction motor (4). The apparatus includes an inverter (3) for generating three-phase AC voltage (VWU, VUV, VVW); a speed deviation signal generator (7), an amplitude controller (8) for controlling the amplitude of the speed deviation signal, an adder (9) for adding together a voltage signal which conforms to the actual speed and the speed deviation signal which has been controlled, a rectangular waveform signal generator (13, 14, 21) and a pulse width modulator (22, 23a, 23b, 23c. NOT1 to NOT3 and 24 to 29). The rectangular waveform signal generator is adapted to produce a three-phase rectangular signal (AS min , BS min , CS min ) whose frequency is proportional to the output voltage value of the adder (9). The rectangular signal of each voltage phase is modulated in pulse width on the basis of the speed deviation, the inverter (3) being controlled by each resulting pulse-width modulated rectangular signal to thereby vary the effective value of the three-phase AC voltage. …<??>The apparatus can prevent torque irregularity and excitation noise in a driven motor with smooth rotation in a low speed region, even under fluctuating load. |
