In the use of permanent magnet brushless motor running wave power system, power grid for the isolated network and load for civilian power。 According the model control (IMC) as the core, within this paper puts forward the fundamental wave and harmonic disturbance instantaneous value feedback controller combined control method of repetitive controller,The methods to analyze and improve the three-phase inverter under the condition of unbalanced load produced by the asymmetric three-phase output voltage to achieve the objective of the output waveform symmetry. Finally, paper used the Matlab simulation verify the scheme for unbalanced load has a strong inhibitory effect..