Abstract: In this paper, the speed regulation problem in fundamental subspace and the harmonic current suppression problem in harmonic subspace of the dual-three phase permanent magnet synchronous machine (PMSM) system subject to multi-source lumped disturbances are studied, respectively. Firstly, a non-cascade control structure is adopted in the fundamental subspace. The generalized proportional integral observer (GPIO) is designed to estimate the multi-source fast-varying disturbances in speed loop of the fundamental subspace. Secondly, the barrier function is introduced on the basis of the traditional proportional differential feedback controller to overcome the overcurrent protection problem of q-axis current. Then, the current constrained composite controller based on GPIO is obtained by combining the disturbance estimation. Thirdly, two GPIOs are designed to accurately estimate the multi-source fast-varying disturbances in the current loop of harmonic subspace. A composite controller is formed by combining with the proportional feedback controller to suppress the harmonic currents in two current loops. Finally, the rigorous stability analysis is demonstrated and the effectiveness of the proposed method is verified by contrast experimental results.