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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]

For the purpose of reducing cost and volume, techniques of reconstructing three-phase currents through a single current sensor have been reported for permanent magnet synchronous motor vector control system. In existing studies, the reconstruction precision is largely affected by the dead zones in space vector PWM plane, which requires additional efforts to compensate the dead zones either by modifying pulse width modulation (PWM) modulation strategy or by phase-shifting of PWM signal. In this paper, a novel zero voltage vector sampling method (ZVVSM) is proposed, which can move the current reconstruction dead zones in low modulation region and sector boundary regions toward the outline of the space vector hexagon without modifying PWM signal. By arranging the single current sensor at a novel position, the proposed method is able to sample current in two zero voltage vectors (ZVV). ZVVSM avoids the complicated algorithms as well as the increase of the switching times, so that it is beneficial to the PMSM drive performance. The proposed method is validated by both simulation and experiments. [ABSTRACT FROM AUTHOR]