In long-cable-fed permanent magnet synchronous motor drive systems, LC filter is employed between the voltage source inverter and the cable to mitigate reflected overvoltage. However, the resonance induced by the LC filter worsens the dynamic response, making the system prone to instability when increasing the control gain. To overcome this bottleneck, a cascaded model-assisted active disturbance rejection control strategy with fast and robust dynamic performance is proposed in this paper. The model-assisted extended state observer processes known system resonance information as the derivative of total disturbance, substantially decreasing its dependency of high bandwidth and thus reducing the settling time. Additionally, a precise transfer function of control system is derived, and the control parameters are meticulously designed based on the frequency-domain metrics to ensure robustness. Experimental validation on a long-cable-fed PMSM drive system confirms significant improvements in motor current control’s dynamic performance, achieving a reduction in settling time by over 72% and improving robustness compared to existing methods.

The sensorless control method based on back electromotive force (BEMF) observers has garnered significant attention in the field of medium- to high-speed permanent magnet synchronous motor (PMSM) drives. However, traditional BEMF observers, due to their low-pass characteristics, struggle to handle DC errors caused by factors such as measurement inaccuracies and inverter nonlinearity, leading to degraded sensorless control performance. Moreover, some advanced methods are constrained by specific design frameworks, resulting in complex observer structures that are not conducive to practical implementation. Therefore, in this paper, a simple and flexible inverse design method for the observer based on a generalized BEMF observer model is first proposed. Subsequently, the method is employed with the gradient descent algorithm to develop a frequency-adaptive observer (FAO), which can completely eliminate DC errors. The proposed observer exhibits zero phase lag and amplitude attenuation at the fundamental frequency of the PMSM, with the fundamental frequency information provided by the frequency-adaptive rule. Compared to other observers, the proposed observer has a simpler structure and is easier to implement. Furthermore, a small-signal model of the FAO is established through linearization to facilitate parameter tuning, and its stability is analyzed based on Lyapunov theory. Finally, comparative experiments are conducted on a 1.5 kW PMSM platform, where the proposed FAO is compared with other observers, validating its effectiveness and feasibility.

Active disturbance rejection control is implemented in a LC-filtered surface-mounted permanent magnet synchronous motor (SPMSM) drive system to enhance current control dynamics. However, the combined effects of computation one-beat delay and the pulse-width modulation zero-order hold (ZOH) effect significantly degrade system stability and dynamic performance. To address these limitations, an improved predictive extended state observer (ESO) with an accurate ZOH discretization method is proposed to ensure fast and robust dynamic performance. The predictive ESO predicts one beat to compensate for the delay effect, while the ZOH discretization yields a more precise discrete dynamic model of the system. These combined improvements substantially enhance the system’s phase and gain margins, leading to superior dynamic performance. Furthermore, a discrete-domain transfer function of the control system is analytically derived, with the control parameters systematically designed using frequency-domain analysis to guarantee robust performance. Experimental validation on a LC-filtered SPMSM drive system demonstrates remarkable enhancement in current control dynamics while maintaining sufficient robustness.

Tracking errors arise when proportional–integral (PI)-based current control with traditional pole-zero cancellation is applied to permanent magnet synchronous motors (PMSMs) with low inertia, which has remained underexplored. Therefore, an in-depth analysis is conducted in this article and reveals the incomplete effectiveness of feedforward and active damping used in traditional pole-zero cancellation control for back electromotive force (BEMF) compensation in low-inertia PMSMs. To resolve these issues, a second-order model for PMSMs is developed to reveal the essential influence of inertia on current. Based on this model, a speed-independent current control (SICC) strategy is proposed in the discrete-time domain. Adopting the novel inertia-robust pole-zero cancellation, the SICC method combines error controller and BEMF compensation, which is capable of handling conjugate poles of the PMSM model and achieves the double-integrator performance, whereas traditional pole-zero cancellation in PI-based methods cannot. In addition, direct discrete design is proposed to obtain better dynamic performance for low-switching frequencies compared with continuous design, to accommodate different scenarios of PMSMs with low inertia. Finally, experimental comparisons on a 750 W PMSM platform validate the effectiveness of the proposed SICC approach.