In order to mitigate harmonics of the grid input current, passive filters are applied widely in the power electric systems. The LC resonance and the negative input impedance are important concerns in ...the reduced dc-link capacitance motor drive system. In this paper, an active damping control method is proposed to suppress the LC resonance by the direct damping current approach, which can formulate the pole distribution of the drive system. Different control laws have been analyzed, and the stability analysis is evaluated by the Routh-Hurwitz criterion. Meanwhile, the active damping control method is realized by the voltage command, which can overcome the limited bandwidth of the current controller. Since the generation of the direct damping current only depends on the dc-link voltage, the proposed active damping control method is robust. Compared with the virtual impedance methods, parameters can be accurately optimized by Bode diagrams after adopting the proposed active damping method. Simulation and experimental results are provided to verify the effectiveness of the proposed method.
High-frequency (HF) signal injection has been widely used in the sensorless control of interior permanent magnet synchronous motor (IPMSM) drives for zero- and low-speed operation. However, the ...audible noise pollution caused by induced HF current has restricted its application. To solve this problem, a low-frequency (LF) pulse voltage injection scheme is proposed in this paper. Different from the traditional LF injection methods, by separating the injection and the control periods, it is easy to extract the fundamental and the induced currents without digital filters, which makes the position estimation more realizable. Since the accuracy of position estimation decreases, an enhanced vector-tracking observer based on the harmonic analysis of the discrete position signal is proposed. Then, the stability of the proposed observer is analyzed. The negative effects of estimation errors on position estimation are investigated, and notch filters are adopted to achieve further harmonic reduction. Finally, this sensorless control method is verified by experiments on a 2.2-kW IPMSM drive platform.
Rotor position and speed estimation methods are consolidated to reduce the cost and volume of permanent magnet synchronous motor (PMSM) sensorless control drives while maintaining high performance. ...Advanced nonlinear algorithms require accurate design for precise estimation tracking throughout the entire PMSM operation range. This paper presents a broad review of the main high-speed estimation methods for sensorless PMSM drives. First, the stability constraints and design methodologies of the main estimation techniques presented in the literature are discussed. In the second part, it is investigated the new observer design trends, which are used under non-ideal conditions, such as robustness to distortions, the effects of parameter variation, sensorless parameter estimation, and low sampling-frequency-to-speed ratio operation. Future trends on the design of observers for high-speed sensorless PMSM drives are also discussed.
With the increasing environmental concerns, a paradigm shift towards electric and hybrid electric vehicles is expected. Switched Reluctance Motors (SRMs) have emerged as a viable competitor to other ...established electrical machines. SRMs are known for their simple construction, robustness, inherent fault tolerant structure and low production and maintenance costs. Moreover, the machine has gained interest due to the absence of permanent magnets or windings in the rotor structure, which significantly reduces production costs when compared to other electric motors. The SRM, however, present some known drawbacks, such as increased torque ripple and acoustic noise production, as well as a highly nonlinear behavior. Through the use of adequate control strategies, however, the main challenges of the machine can be overcome. Thus, this paper presents a state-of-the-art review of the advanced control of SRMs, encompassing current regulation strategies, torque control strategies and vibration suppression techniques. First, two categories of current controllers are reviewed: model-independent and model-based. Next, indirect and direct torque control methods are explored. Then, three approaches to vibration suppression are discussed, namely active cancellation, current profiling and direct instantaneous force control. Lastly, a summary of each topic is presented and suggestions of future research topics are listed.
Model-based position-sensorless control of interior permanent magnet synchronous motors (IPMSMs) is promising for high-speed operation, besides the fact that the estimation accuracy degrades by dc ...errors from integration, measurements, and parameter uncertainties. In this article, a new complex-coefficient adaptive disturbance (CCAD) observer based on the back electromotive force estimation is proposed. The proposed CCAD observer has a bandpass characteristic and possesses resonating peak response at the corner frequency which is adapted to the synchronous rotor frequency. This adaptive resonant frequency effectively improves the robustness to dc errors, without magnitude loss and phase delay. The proposed observer is also compact and has lower order as compared to the other bandpass observers, and that substantially benefits in the embedded implementation. To configure the proposed CCAD observer, a reverse observer design scheme is analyzed. The stability of the observer is guaranteed based on a speed adaptation law, and small-signal approximation is then applied to linearize the proposed observer for parameter design and dynamic analyses, which have not been well discussed in literature. The proposed method is verified by experiments for a 15 kW IPMSM drive.
In this article, a low-ripple continuous control set (CCS) model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed. The inherent high nonlinearity of the ...SRMs makes it difficult to solve the optimization problem in the CCS MPTC algorithm analytically. To address this issue, an equivalent linear SRM model is adopted, and the cost function is also properly modified. Then, with the torque boundary values provided by executing the voltage vectors of an improved switching table, the optimization problem in the CCS MPTC method becomes simple and analytically solvable. The Lagrange multiplier method is employed to solve this optimization problem analytically and generate the optimum torque reference values for the active phases. Based on the estimated torque variation rates, the duty cycles for each phase are calculated. Extensive simulation and experimental tests are carried out in a four-phase 8/6 SRM setup. These testing results reveal that the proposed CCS MPTC method shows much lower torque ripples and current ripples in a wide speed range with a low computational burden than the existing finite control set MPTC methods.
Pulsating high-frequency (HF) signal injection is a common saliency-based sensorless control method applied for synchronous reluctance motor (SynRM) drives. However, the accuracy of the rotor ...position estimation deteriorates due to severe cross-coupling effect and voltage fluctuations. To solve this problem, a measured reference frame HF voltage injection (MHFVI) method is proposed in this paper. A total of two discontinuous pulsating square-wave voltage signals are injected along with two measured axes, and position information is extracted with a cross-coupling factor (CCF) introduced, which can inherently account for the estimation error caused by the cross-coupling effect. The signal processing scheme of the proposed MHFVI method is further developed to be robust to voltage errors, meanwhile has less fluctuation in the position estimation error. The position estimation error is investigated and analyzed based on the finite element analysis results and the introduced CCF is calculated based on the SynRM current-flux characteristics models. Finally, the proposed method is verified by experiments on a 3-kW SynRM drive platform.
This paper proposes a new sensorless control scheme of interior permanent magnet synchronous motors (IPMSMs) using high-frequency (HF) orthogonal square-wave voltage injection into a stationary ...reference frame (SRF). This method is an improvement on the conventional HF rotating sinusoidal voltage injection into the SRF. First, discrete sequences of the HF currents are applied to establish the whole signal process. Then, a position estimation method without low-pass filters is proposed, and the phase shifts caused by high-pass filters are also reduced. Therefore, the proposed sensorless control method would not be adversely affected by digital filters, which can solve the common drawbacks of the current SRF-based injection methods. Furthermore, the digital delay in drive systems is considered, and its negative influence can be eliminated as well. The sensorless control method is verified by experiments on a 2.2-kW IPMSM drive platform.
In this article, a novel model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed based on the equivalent linear SRM model and the improved switching table. ...First, an improved switching table with only six switching states is developed based on the inductance characteristics. The adoption of this improved switching table not only reduces the computational burden by 25% but also improves the torque control performance and system efficiency at high-speed region. However, the look-up-table (LUT) based MPTC methods suffer from occupying numerous storage space. To ease this issue, the simple linear SRM model is utilized. The flux-linkage and torque equivalent transformations are introduced to address the difference between the linear and nonlinear SRM models. With these transformations, the MPTC realized on the linear SRM model is proposed. Compared to 1530 storage units consumption to store three two-dimensional (2-D) LUTs in the LUT-based MPTC methods, the proposed method only occupies 228 storage units. Experimental results on an 8/6 SRM setup verify that the proposed method effectively eliminates the commutation torque ripple with lower execution time, less storage space, and improves the torque control performance at a high-speed range compared with the conventional LUT-based method.
Model-based state-of-charge (SOC) and state-of-health (SOH) estimation for lithium-ion batteries has been widely applied in electrified vehicles, while the SOC and SOH estimators are highly coupled ...and nonlinear in conventional techniques. This leads to a bulky design of observer network and complicates the stability analyses. In this article, a new reduced-decoupling SOC and SOH coestimation algorithm based on convex optimization is proposed. This scheme estimates the battery SOC from the battery model and does not require the classic Coulomb-counting method. Therefore, it can decouple the capacity estimation from the SOC estimator and reduce the strong interaction existing in conventional coestimation methods. Besides, all state variables can be solved together by one estimator, which is straightforward and avoids the complicated observer network. Owing to the decoupling design, the stability of the proposed method becomes more intuitive and can be always guaranteed according to the convexity analysis without using other stabilizing approaches. In consequence, a weak-interaction and robust coestimation algorithm of SOC and SOH can be realized by the proposed technique. The experiments on a 5.4-Ah lithium polymer battery are implemented to validate the feasibility of the algorithm.
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