Torque Improvement in a Seven-Phase Machine by Injecting the Higher Current Harmonics

In this study, the torque increase due to current harmonics injectection into a seven-phase machine was investigated analytically and using finite element analysis software (FEA). It is possible to increase torque by injecting current harmonics in a multi-phase machine. Torque in a seven-phase machine can be increased by injecting the third and fifth current harmonics. In this study, firstly, the torque increase with current harmonics in a seven-phase machine was investigated analytically. Then, in order to prove these theoretical findings, a permanent magnet seven-phase machine design was made in an FEA software. Three different simulation experiments were conducted using this design. In the first simulation, the machine was driven only with the fundamental component of the current. In the second simulation, the third harmonic was injected additional to the fundamental component of the current. In the last simulation experiment, the fifth harmonic was injected in addition to the fundamental component and the third harmonic. As a result of these three simulations, it was observed that the torque of the machine increased significantly without ripple for each injected harmonic.