Jiwon Yoo

This article analyzes the effect of angle estimation error on the sensorless torque control of the permanent-magnet synchronous motor (PMSM). The actual torque of PMSM may differ from the torque reference due to the angle error in sensorless control. Furthermore, this torque discrepancy can cause instability to the control system, especially in the flux weakening region. The instability is highly dependent on the gain setting of the controller and observer in the control loop. To mitigate the ad

This article proposes an online maximum torque-per-Ampere (MTPA) control of an interior permanent-magnet synchronous motor (IPMSM) based on the square-wave voltage signal injection. Because the proposed method does not rely on a position sensor, it is applicable to sensorless IPMSMs. The proposed algorithm consists of a dynamic inductance estimator, frequency-adaptive flux observer, and an MTPA tracking controller. The proposed inductance estimation utilizes the pulsating square-wave voltage inj

In this article, the torque ripple of an induction motor due to dc injection for the stator resistance estimation is analyzed. In the analysis, the fundamental component of rotor flux is used for rotor flux orientation to avoid the perturbation issue in synchronous reference speed. On the synchronous reference frame, flux and torque fluctuation due to injected dc and arbitrary second harmonic current is calculated. Furthermore, the current reference that nullifies the fundamental frequency torqu

This article analyzes the effect of discretization in the frequency-adaptive flux observer (FAO). Although FAO has structural simplicity and ease of implementation, the discrete-time FAO has phase and gain errors in fundamental flux estimation. As a result, the estimated flux might be erroneous, especially in the high-speed region. For accurate flux estimation, this article analyzes how the voltage synthesis in the pulsewidth-modulation affects the stator flux. Through the analysis, the backward

The overmodulation scheme plays an essential role in the dynamic performance of the current regulation under voltage limitation. This article analyses how the nonlinearity of the voltage hexagon affects dynamic overmodulation. Most dynamic overmodulation schemes had considered the voltage hexagon as the limit of the output voltage to maximize the voltage utilization. However, these schemes do not show uniform dynamic performance according to the rotor position on the voltage hexagon. To overcome

This article introduces an experimental parameter identification method for induction motor (IM) drives, aiming to accurately identify the motor parameters while considering magnetic saturation throughout the entire operating point. To address the rank-deficiency problem in experimental parameter identification for IMs, this article proposes a solution by constructing a stator inductance lookup table (LUT) with the assistance of finite element analysis. By conducting experimental tests, the leak

In this paper, a method to compensate parameter variation of IPMSM for accurate torque control in sensorless control mode is proposed. First, a full-order observer for flux estimation of IPMSM is described, and how the inductance error affects the error of back-EMF estimation is analyzed. Next, the condition in which the real torque and the calculated torque based on current-model are the same is derived. And, an inductance compensator for achieving the condition is designed. The compensator can

Due to the high dv/dt of the voltage source inverter (VSI), the signal quality of the Hall-effect sensors for current feedback would deteriorate. Especially in signal injection sensorless drives, which utilize the differentiation of output current, the current sensing noise induced by high dv/dt of VSI would not be negligible. This paper proposes a shielding strategy for the dv/dt noise reduction in the current sensor of VSI. Firstly, it is shown that the conventional shielding cable connected t

This paper proposes an experimental parameter identification method for induction motor drives. To find the motor parameters at each operating point, the rank-deficiency problem is circumvented by the finite element analysis (FEA). The stator inductance look-up-table (LUT) is constructed assisted by FEA, and the leakage inductance and the rotor resistance are calculated based on the experimental tests. The proposed parameter identification can be used for a wide range field-oriented control in t

The overmodulation scheme plays an essential role in the dynamic performance of the current control under the voltage limitation. This paper analyses how the non-linearity of the voltage hexagon affects the dynamic overmodulation. Most dynamic overmodulation schemes had considered the voltage hexagon as the limit of the output voltage to maximize the voltage utilization. However, these schemes do not show the uniform dynamic performance according to the rotor position on the voltage hexagon. To

This paper analyzes the stability of sensorless permanent-magnet synchronous motor (PMSM) drives, which adopts the proportional-integral (PI) controller-type position estimator. Due to the limited bandwidth of the angle estimation, the sensorless position estimator can cause a transient angle error, leading to a torque discrepancy between the reference and the actual value. This phenomenon can be more severe in the flux weakening region. If this torque error is not damped sufficiently through th

This paper analyzes the effect of gain scheduling in the full-order flux observer for sensorless PMSM drives. The analysis shows that the conventional gain scheduling with fixed pole locations is vulnerable to the magnetic spatial harmonics of PMSM, especially at low speeds. To reduce the spatial harmonic disturbance on the angle estimation, a complex-vector style gains scheduling is proposed in this paper. The proposed gain scheduling inherently provides the speed-adaptive pole allocation, and

Capturing multi-scale context within feature maps is crucial for semantic segmentation. With the success of the Vision Transformer (ViT), recent models have been designed with transformer decoders to capture it. However, these models face limitations in utilizing diverse contextual information due to the inherent nature of the attention mechanism and structural constraints. Typically, multi-head attention which leads to similar receptive fields for each token feature is achieved at the expense o

This article proposes a position-sensorless maximum torque-per-ampere (MTPA) tracking control method for the low-speed region. Unlike the conventional MTPA tracking algorithms which count on the stator flux observation, the proposed algorithm performs the MTPA operation solely through the high frequency voltage injection. To achieve sensorless MTPA operation, the MTPA criterion is interpreted through dynamic inductance terms, which are estimated online through tilted high-frequency voltage vecto

This paper analyzes the effect of angle estimation error on the sensorless torque control of the permanent-magnet synchronous motor (PMSM). The actual torque of PMSM may differ from the torque reference due to the angle estimation error in sensorless control. Furthermore, this torque discrepancy can cause instability in the control system, especially in the flux weakening region. In order to mitigate the adverse effect of the angle estimation error, the new torque feedforward method considering