A generalized fault-tolerant control (FTC) strategy for the field-oriented control (FOC) and direct torque control (DTC) of five-phase fault-tolerant permanent magnet (FPFTPM) motors under various open-circuit faults is presented in this article. Most previous studies regarding FTC target a specific primary control algorithm and involve different reduced-order transformation matrices and additional current controllers, which increase the complexity of the entire drive system. In this study, a solution to the aforementioned problems is devised by developing optimal fault-tolerant voltages, which are derived from fault-tolerant mechanism analysis and steady-healthy design. Because the coordinate transformation need not be changed and additional voltage compensation is not required, a minimal control drive system reconfiguration under various open-circuit faults can be achieved to avoid accommodating the change of the primary control algorithm. The proposed control strategy not only improves the torque performance and dynamic response under healthy and fault conditions, but also adapts to both FOC and DTC. Experimental results for a 2 kW FPFTPM motor prototype are provided to evaluate the proposed strategy.

High reliability and fault-tolerant operation capability are the application requirements of electric vehicles(EVs). In case of the drive system suffering from inter-turn short-circuit (ITSC) fault, it is necessary to avoid the aggravation of the fault and ensure the normal output performance, this paper proposed a torque ripple minimization control strategy for ITSC fault based on the open-winding (OW) five phase fault tolerant fractional slot concentrated winding interior permanent magnet (FTFSCW-IPM) motor drive system with common DC bus. Once the ITSC fault is detected, the fault phase is active open-circuit (OC) (null the current of the normal part in the fault phase) and connected to a voltage sensor. In this way, the torque ripple minimization control strategy can deal with the OC fault and ITSC fault. For the OC fault, the equal amplitude phase current modulation strategy is adopted based on the carrier-based pulse width modulation (CPWM). For the ITSC fault, this paper proposed a feedforward compensation approach to eliminate the influence of the short-circuit loop current. The novelty of the proposed method is that the compensation can be real-time estimated using the zero-sequence voltage (ZSV) and zero-sequence current (ZSC), even the ITSC level changes. Simulation and experimental results demonstrate the effectiveness and feasibility of the proposed method.

This paper proposed an on-line inter-turn short-circuit (ITSC) fault diagnosis approach by observing the DC component in the torque deviation for the open-end winding (OW) five-phase brushless fault-tolerant hybrid-excitation interior permanent magnet motor (BFTHE-IPM). To eliminate the impact of ITSC fault on torque and guarantee a disturbance-free operation' the strategy of torque ripple minimization is proposed-in which the virtual direct-quadrature axis current feedforward compensator is adopted. Moreover, the compensation is obtained by measuring the zero-sequence current without calculating short-circuit turns ratio and short-circuit current. Therefore, computational quantity and complexity of the algorithm are greatly reduced. Simulation and experimental results verify the effectiveness of the proposed method.

In this paper, a new zero-sequence current suppression control strategy for five-phase open-winding fault-tolerant fractional-slot concentrated-winding interior-permanent-magnet (FTFSCW-IPM) motor drive system with common DC bus is proposed. By unequal distribution of the zero voltage vector, the proposed method can well suppress the zero-sequence current caused by dead-time effect that the conventional eliminating method cannot be achieved. First, the dead-time effect to the zero-sequence current is discussed. Then the zero-axis controller is deigned to obtain the reference common-mode voltage. Last, according to the principle of the unequal zero voltage vector distribution, the switching sequence of the two inverters can be calculated, and the maximum modulation index is also first deduced in detail. The proposed method is proved by the simulation and experimental results.

The difficulty of open-switch fault detection in an open-winding inverter is that the fault at the diagonally opposite position within the H-bridge power cell has the same fault characteristics. To solve this problem, this paper proposes an open-switch fault detection method based on open-winding (OW) five-phase fault-tolerant permanent-magnet (FPFTPM) motor drives. The detection method includes three steps: first, the drives open-switch fault is detected by monitoring the component of the third harmonic residual in the stationary reference frame; second, the least squares iterative method based on the forgetting factor is used to identify the relationship between the residual components, which determines the faulty phase and the faulty phase current type; third, an online current injection test method is proposed to accurately identify the open-switch within the H-bridge power cell. Based on the above steps, the open-switch fault at the diagonally opposite position within the H-bridge power cell could be accurately identified. The novelty of the proposed method lies in the possibility that the open-switch fault detection of any switches within the one H-bridge power cell could be accurately achieved by an online current injection test and does not require hardware changes. The experimental results demonstrate the effectiveness of the proposed detection method.

This paper presents a composite control strategy for five-phase fault-tolerant fractional-slot concentrated winding interior permanent magnet (FTFSCW-IPM) motor drives, aiming to alleviate the long-standing trade-off between fast dynamic response, chattering suppression, and disturbance rejection in sliding mode control. A variable exponential fast terminal reaching law with a continuous switching function is developed to explicitly shape the reaching dynamics, enabling rapid convergence when the system state is far from the sliding surface while ensuring smooth behavior near the surface. To further enhance robustness against load torque disturbances, a Luenberger torque disturbance observer (LTDO) with a slightly enhanced correction structure is incorporated as a feedforward compensation channel, thereby decoupling disturbance rejection from the sliding-mode switching gain design. In addition, a systematic comparative study involving four representative control schemes is conducted to clearly distinguish the individual and combined effects of the fast terminal sliding mode structure and the disturbance observer. Both simulation and experimental results demonstrate that the proposed strategy achieves excellent speed tracking performance and improved disturbance rejection under sudden load torque variations.