A Three-Phase Motor System with 1 kW Rating and Six-Step Inverter Control

This document presents a three-phase motor system rated at 1 kW, operating with a DC voltage of 500 V and a speed of 3000 rpm. The motor is driven by a six-step voltage inverter, which is implemented as a MOSFET bridge component from the SimPowerSystems™ library. A speed regulator controls the DC bus voltage to maintain stable operation. The inverter gate signals are generated by decoding the motor's Hall effect sensor signals, ensuring proper commutation timing. The three-phase output of the inverter is applied to the stator windings of the Permanent Magnet Synchronous Motor (PMSM) block. The mechanical load torque is initially set to 0 and reaches its rated value of 11 N·m at t = 0.1 seconds. The system employs a dual-loop control architecture. The inner loop synchronizes the inverter gate signals with the back-EMF of the motor, typically implemented using position feedback from sensors or sensorless algorithms for field orientation. The outer loop regulates the motor speed by dynamically adjusting the DC bus voltage based on the error between the reference speed and the actual measured speed. This control strategy ensures stable motor operation under varying load conditions, such as the step change in torque at t = 0.1 seconds. Further details on the control loops: The inner loop maintains synchronization between the rotor magnetic field and the stator field by controlling the commutation timing, which can be implemented in code using phase-locked loop (PLL) techniques or direct Hall signal decoding. The outer loop monitors motor speed through an encoder or estimated algorithm and modulates the DC bus voltage via PWM control or DC-DC converter commands to minimize speed error. Considerations for inverter efficiency and power factor are critical for system performance; optimization may involve switching frequency adjustments, dead-time compensation, and power factor correction algorithms to enhance overall motor drive efficiency.