| 摘要 |
PURPOSE:To maintaining the maximum torque of an induction motor approximately constantly in full frequency range by controlling the basic wave component of the output waveform of an inverter in accordance with a pattern signal and forming a relation in which the ratio of air gap inducing voltage to frequency becomes always constant. CONSTITUTION:A 3-phase induction motor is driven through the DC power source 2 of a 3-phase full-wave rectifier and a 3-phase bridge type switching circuit 4. The output of a speed setting unit 7 is converted via a frequency converter 8, which produces a signal S2 proportional to the desired output frequency, a pattern capable of obtaining basic wave component becoming always constant in the ratio of the air gap inducing voltage and the frequency is formed in a pattern generator 9 which has a memory and an address selector, and transistors Tr1, Tr2 are controlled by the synthesis of the output signal and the signal S2. Accordingly, it can control with constant E/f and can readily maintain the maximum torque constantly in full frequency range. |
