CONTROL OF VOLTAGE TYPE INVERTER IN ELEVATOR

摘要

PURPOSE:To suppress vibration within an allowable range of noise level at the time of low speed operation in a voltage type inverter for elevator performing high speed switching. CONSTITUTION:A CPU 21 in a voltage type inverter unit outputs a switching frequency command for controlling the switching frequency as a function of the speed such that the switching frequency is low in low speed region while high in high speed region. The switching frequency command is subjected to A/D conversion and employed in the control of oscillation frequency of a triangular wave oscillation circuit. Since the frequency of the triangular wave oscillation circuit decreases in low speed region, switching frequency outputted from a comparator 26 decreased in low speed region. Consequently, disturbance of output waveform of inverter due to a dead time provided from a drive circuit 3 is suppressed resulting in a sinusoidal output.