Gaolin Wang

DSP-Based Control of Sensorless IPMSM Drives for Wide-Speed-Range Operation

A position sensorless control strategy of an interior permanent magnet synchronous motor (IPMSM) drive based on a digital signal processor (DSP) is proposed. To achieve sensorless wide-speed-range operation, a hybrid position estimation strategy combining the high frequency (HF) signal injection method with the electromotive force (EMF)-based method is presented. At low-speed range, an HF voltage signal is injected, and a rotor position observer is designed to improve the robustness to the load disturbance. At middle- and high-speed ranges, a sliding-mode observer based on the extended EMF of IPMSM is designed for sensorless operation. Moreover, during the switch-over area, the two position estimation methods are both enabled for the sensorless control. A software phase-locked loop and a dead-time compensation strategy are adopted to improve the position estimation accuracy. The experimental results demonstrate the feasibility of the control strategy with a sensorless IPMSM drive based on a DSP.

Analysis of the Phase-Shifted Carrier Modulation for Modular Multilevel Converters

The modular multilevel converter (MMC) is an emerging topology for high-power applications and is considered as the development trend of the high-voltage power converters. In this paper, general implementation of the phase-shifted carrier (PSC) modulation with a capacitor voltage balancing method for MMC is first introduced. Then, the mathematical analysis of PSC modulation for MMC is performed to identify the PWM harmonic characteristics of the output voltage and the circulating current. Moreover, influence of the carrier displacement angle between the upper and lower arms on these harmonics is also studied. Using this analysis, the optimum displacement angles are specified for the output voltage harmonics minimization and the circulating current harmonics cancellation, respectively. The harmonic features of the line-to-line voltage and the dc-link current are also investigated. Moreover, an extension of the PSC modulation for MMC with full-bridge submodules is also proposed which can increase the equivalent switching frequency of the output voltage and circulating current by two times compared with the conventional MMC. Finally, the findings are verified experimentally on a prototype of MMC.

Adaptive Compensation Method of Position Estimation Harmonic Error for EMF-Based Observer in Sensorless IPMSM Drives

To improve the performance of sensorless interior permanent magnet synchronous motor (IPMSM) drives, a quadrature phase-locked loop (PLL) with an adaptive notch filter (ANF) is proposed for the model-based sliding-mode observer (SMO). The position estimation error with the sixth harmonic distortion caused by the inverter nonlinearity and the flux spatial harmonics is analyzed. The ANF based on adaptive noise canceling principle combined with the quadrature PLL is proposed to diminish the estimation harmonic error. This method can adaptively compensate the harmonics in the estimated electromotive force to eliminate the corresponding position estimation error. The estimated harmonic coefficients from the ANF can be continuously self-tuned using the least-mean-squares algorithm according to the estimated position information. The effectiveness of the proposed method is verified with the experimental results at a 2.2-kW IPMSM sensorless drive.

Maximum Efficiency Per Ampere Control of Permanent-Magnet Synchronous Machines

High-efficiency electric drive systems claim not only optimally designed electric machines but also efficiency-oriented control strategies. Taking machines and drives into synergetic consideration, this paper proposes a novel vector control algorithm named maximum efficiency per ampere (MEPA) control, aiming to maximize the efficiency of permanent-magnet synchronous machines (PMSMs) during operation. Different from conventional id = 0 or maximum torque per ampere control, MEPA fully considers the cross effect and iron loss from which the full-order loss model of PMSMs is built. Due to the proposed concise and accurate analytical approach to iron loss calculation, the optimal current phasor angle for MEPA can be quickly found, and the estimation of efficiency is consistent with measurement. Comparison among different control algorithms is drawn from both analytical and experimental results, from which the effectiveness of MEPA is verified.

Quadrature PLL-Based High-Order Sliding-Mode Observer for IPMSM Sensorless Control With Online MTPA Control Strategy

To improve performance of the field-oriented controlled position sensorless interior permanent magnet synchronous motors (IPMSM) drive, a model-based high-order sliding-mode observer with a software quadrature phase-locked loop (PLL) is proposed. A simplified method of designing the feedback gain matrix of the sliding-mode observer is introduced for easy application. The PLL coefficients are analyzed by considering the expected position estimation error and the operating condition. Compared with the conventional arc-tangent calculation method, the proposed quadrature PLL estimation method can be immune to the influence of the noise and distortion. To achieve the robust high-efficiency operation of the sensorless IPMSM, an enhanced online maximum torque per ampere (MTPA) control strategy without motor parameters dependent is adopted for the vector control drive. The optimal MTPA operation is achieved by searching the optimal current angle online to make the current amplitude be the minimum. The effectiveness of the proposed method is verified with a 2.2-kW IPMSM sensorless drive.

A Novel Control Method for Transformerless H-Bridge Cascaded STATCOM With Star Configuration

This paper presents a transformerless static synchronous compensator (STATCOM) system based on multilevel H-bridge converter with star configuration. This proposed control methods devote themselves not only to the current loop control but also to the dc capacitor voltage control. With regards to the current loop control, a nonlinear controller based on the passivity-based control (PBC) theory is used in this cascaded structure STATCOM for the first time. As to the dc capacitor voltage control, overall voltage control is realized by adopting a proportional resonant controller. Clustered balancing control is obtained by using an active disturbances rejection controller. Individual balancing control is achieved by shifting the modulation wave vertically which can be easily implemented in a field-programmable gate array. Two actual H-bridge cascaded STATCOMs rated at 10 kV 2 MVA are constructed and a series of verification tests are executed. The experimental results prove that H-bridge cascaded STATCOM with the proposed control methods has excellent dynamic performance and strong robustness. The dc capacitor voltage can be maintained at the given value effectively.

Position Estimation Error Reduction Using Recursive-Least-Square Adaptive Filter for Model-Based Sensorless Interior Permanent-Magnet Synchronous Motor Drives

To improve the performance of sensorless interior permanent-magnet synchronous motor (IPMSM) drives, an adaptive filter (AF) using recursive-least-square (RLS) algorithm is proposed for the electromotive force (EMF) model-based sliding-mode observer with a quadrature phase-locked loop (PLL) tracking estimator. The inverter nonlinearities and flux spatial harmonics, which cause the position estimation error with the sixth harmonic, are analyzed. An AF based on the adaptive noise-cancelling principle in cascade with a quadrature PLL is adopted to remove the harmonic estimation error. According to the harmonic characteristics of the estimation error from the quadrature PLL, the AF coefficients can be continuously updated by the RLS algorithm. The application of the RLS algorithm guarantees the fast convergence rate of the AF. Through the AF using the RLS algorithm, the harmonics of the estimated EMF can be effectively compensated. Therefore, the selected position estimation harmonic error can be eliminated. The effectiveness of the proposed method is verified with the experimental results at a 2.2-kW sensorless IPMSM drive.

Fault Diagnosis and Tolerant Control of Single IGBT Open-Circuit Failure in Modular Multilevel Converters

The modular multilevel converter (MMC) is distinguished by its modularity that is the use of standardized submodules (SMs). To enhance reliability and avoid unscheduled maintenance, it is desired that an MMC can remain operational without having to shut down despite some of its SMs are failed. Particularly, in this paper, complete fault diagnosis and tolerant control solution, including the fault detection, fault tolerance, fault localization, and fault reconfiguration, have been proposed to ride through the insulated gate bipolar transistor open-circuit failures. The fault detection method detects the fault by means of state observers and the knowledge of fault behaviors of MMC, without using any additional sensors. Then, the MMC is controlled in a newly proposed tolerant mode until the specific faulty SM is located by the fault localization method; thus, no overcurrent problems will happen during this time interval. After that, the located faulty SM will be bypassed while the remaining SMs are reconfigured to provide continuous operation. Throughout the fault periods, it allows the MMC to operate smoothly without obvious waveform distortion and power interruption. Finally, experimental results using a single-phase scaled-down MMC prototype with six SMs per arm show the validity and feasibility of the proposed methods.

ADALINE-Network-Based PLL for Position Sensorless Interior Permanent Magnet Synchronous Motor Drives

To diminish the harmonic ripple in the rotor position estimation error for sensorless interior permanent magnet synchronous motor (IPMSM) drives, an adaptive linear neural (ADALINE)-network-based filter with a quadrature phase-locked loop (PLL) position observer is proposed. A fundamental model-based sliding-mode observer is used to obtain back electromotive force information. The harmonic content in the position estimation error caused by inverter nonlinearities and flux spatial harmonics is analyzed. According to the harmonic characteristics of the estimated rotor position, the ADALINE-network-based filter is adopted to track and compensate the selective harmonic ripple in the rotor position estimation error through continuously updating the filter weights online. Whereby, the position estimation accuracy can be improved and the position sensorless control performance can be promoted. The proposed method was verified for a 2.2-kW position sensorless IPMSM drive. Experimental results confirm the effectiveness of the method in suppressing the harmonic ripple in the rotor position estimation error.

Self-Commissioning of Permanent Magnet Synchronous Machine Drives at Standstill Considering Inverter Nonlinearities

Offline parameter identification of permanent magnet synchronous machines (PMSMs) is essential for proper tuning of the controller and position observer for general-purpose drives with sensorless control. This paper proposes a self-commissioning method of electrical machine parameters at standstill only using a voltage source inverter fed drive. The influence of inverter nonlinearities including the effect of parasitic capacitance, which may cause estimation error, is analyzed. And an error model of inductance identification considering different rotor positions is established. Along with high-frequency sinusoidal signal, a supplementary direct current signal is injected into the estimated direct-axis to attenuate the inductance identification error. In addition, a compensation strategy based on the error model is adopted to enhance the accuracy of inductance identification. For stator resistance identification, the linear regression method is adopted to overcome the influence of inverter nonlinearities by injecting the linearly increasing current signal. The proposed method is promising and robust to extract the resistance information from the gradient coefficient of the voltage variation. The effectiveness of the proposed self-commissioning scheme is validated on a 22-kW PMSM drive.