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To reduce the cost and size of the power converters, techniques of reconstructing three-phase current through a single current sensor have been employed in permanent-magnet synchronous motors. In existing studies, the reconstruction precision is largely affected by current reconstruction dead zones in the space vector pulsewidth modulation (PWM) plane, which requires additional algorithms to compensateeither by modifying PWM modulation strategy or by phase-shifting of PWM signal. In this article, a phase current reconstruction method for three-phase inverter with the modification of a twelve sector space vector pulsewidth modulation (TS-SVPWM) is proposed. By arranging a single current sensor on a circuit branch between two power switches, the proposed method can reconstruct the three-phase current of the voltage source inverter and avoid the dead zones located at the sector boundary region. This method can be realized not only with a single Hall-effect current sensor but also with a single shunt resistor, which can expand its application. The proposed method can be a fault-tolerance solution when there are phase current sensor faults. Beside, the three-phase current can be reconstructed when there are open-circuit faults in the power switches. Compared with previous methods, the proposed TS-SVPWM can reduce the phase current harmonics. The effectiveness of the proposed method is validated by experiments. [ABSTRACT FROM AUTHOR]

In single current sensor (SCS) methods, different phase currents should be acquired sequentially under the duration time of specific voltage vectors within each switching period. The sampling asynchronization caused due to sampling delay will inevitably result in the increase of phase current reconstruction error and deteriorate the control performance. According to the fundamental expression formula of three-phase currents in permanent magnet synchronous motor drives, the sampling-delay error (SDE) occurring in the traditional SCS techniques is analyzed in this article. It is demonstrated that the error oscillates at the stator electrical frequency, with the amplitude affected by both the switching frequency and motor speed. Correspondingly, a novel compensation method based on a δ–γ reference frame is presented. There is a simple proportional relationship between δ- and γ-axis error component after filtering the ac component by a notch filter. As a result, the SDE can be easily eliminated without extra complex compensation algorithms introduced. The prominent feature of the proposed method is that it is developed without necessity of motor parameters when compared with previous compensation techniques, making it a more robust solution. Several experimental results are provided to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Current sensing techniques with reduced number of sensors attract a high interest from industry, for the possibility of cost reduction and sampling mismatch reduction. This article puts forward a new single current sensor (SCS) method for a permanent magnet synchronous motor three-phase current reconstruction, with a novel hybrid pulsewidth modulation (PWM) technique introduced. This method is implemented by changing the position of SCS from dc bus to a current branch, and a modified space vector PWM technique is employed to realize the phase current reconstruction. Compared with traditional SCS control methods, the proposed method can relieve the measurement dead-zones at sector boundary region without introducing extra compensation algorithms. Besides, this method can be realized not only with a single hall-effect current sensor but also a single shunt resistor, which further expands the applications and increases the system reliability as well. This method is also available in other motor control with a two-level three-phase PWM voltage source inverter topology. The accuracy and feasibility of the proposed method is validated by the simulation and experimental results. [ABSTRACT FROM AUTHOR]