SPEED CONTROL DEVICE FOR A PERMANENT MAGNETIC SYNCHRONOUS MOTOR CAPABLE OF CONTROLLING SPEED USING A NEUTRAL POINT CLAMPED 3-LEVEL INVERTER

摘要

PURPOSE: A speed control device for a permanent magnetic synchronous motor is provided to reduce voltage stress and a high frequency component in a switching element of an inverter by applying an NPC(neutral point clamped) 3-level inverter to the permanent magnet synchronous motor. CONSTITUTION: A speed control unit(101) controls speed of entire speed section in a permanent magnet synchronous motor. Current control units(103a,103-b) control currents which are outputted from the speed control unit. An inverter(107) drives the permanent magnet synchronous motor using the currents which are controlled in the current control units. The inverter consists of an NPC 3-level inverter. The speed control unit controls the speed of the permanent magnet synchronous motor using a maximum torque control per ampere technique and a weak field control technique according to driving characteristics of the entire speed section.