Resonant Control Strategy Research Articles

Research on resonance control strategy based on electro-hydraulic servo excitation

Research on resonance control strategy based on electro-hydraulic servo excitation

Single-phase photovoltaic off-grid inverter based on quasi-PR control

Given the rapid growth of renewable energy generation, photovoltaic inverters have gained widespread adoption in power generation systems. To achieve improved precision in control and enhanced quality in the output waveform of the inverters, this article presents a single-phase photovoltaic inverter designed for both grid-connected and off-grid systems. It utilizes a quasi-proportional-resonant control technique. Initially, the mathematical representation of the grid-connected and off-grid inverter is established. Following this, the quasi-proportional resonant control strategy is introduced, with the corresponding implementation method of the controller derived from its equivalent block diagram. Furthermore, the control block diagrams of the grid-connected and off-grid inverters undergo a detailed analysis, and the system’s transfer function is obtained from the control block diagram. The incorporation of grid voltage feedforward control is introduced for examining the system’s tracking performance. Ultimately, the proposed control approach is validated for its effectiveness and practicality through Simulink simulation.

Novel Auxiliary Resonant Pole Inverter and its Optimal Control Strategy

Conventional inverters operate in hard‐switching mode, and as the switching frequency increases, the switching losses increase dramatically. Increasing the switching frequency helps reduce the size and cost of the inverter, but too high a switching frequency generates greater switching losses, which affects the inverter's transmission efficiency. In response to the problem that conventional hard‐switching inverters cannot be higher in frequency and have high switching losses and low transmission efficiency, an optimized auxiliary resonant commutated inverter and control strategy are proposed to make the inverter work in soft‐switching mode, which helps reduce the switching losses. The auxiliary converters in the bridge arm topology of each phase of the three‐phase inverter are divided into two groups, and the operating auxiliary converters are selected according to the direction of the load current. When the load current direction is positive, the upper bridge arm auxiliary device works and the lower bridge arm auxiliary device turns off, similarly when the load current direction is negative, the lower bridge arm auxiliary device works and the upper bridge arm auxiliary device turns off, this can ensure that only one group of devices works every half cycle, making the control strategy simple and reducing auxiliary circuit losses. Simulation and experimental verification of the effectiveness of the proposed scheme. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

Non-Isolated Current-Fed Series Resonant Converter with Hybrid Control Algorithms for DC Microgrid

Module-level power electronics can optimize the power generation of photovoltaic panels, which requires a simple topology structure, high power conversion efficiency, and wide voltage gain, corresponding to irradiance variations. This paper proposes a non-isolated current-fed L-C series resonant converter and its control algorithms. The proposed converter can obtain a buck–boost voltage gain with the hybrid control algorithm utilizing the switching frequency modulation and asymmetric pulse width modulation. The proper power stage design can guarantee the soft-switching capability for the entire operating range. Also, the control strategy is designed to obtain a small rms current. The operational principle of proposed converter is analyzed in order to design the resonant tank and control strategy. The performance of designed converter can be verified with the experimental results with a 500 W prototype converter.

Voltage Regulating Strategy of a New LCC/S+L Inductive Power Transfer System

In the voltage control of the inductive power transfer (IPT) system, a cascaded DC-DC converter is normally adopted which reduces the power density. However, the wireless communication between the transmitter and the receiver may lead to a delay of control as well as communication instability. This paper proposes a new LCC/S+L resonance topology for the IPT system, which can realize single-stage voltage regulation on the receiving side with both buck and boost capability. Based on the fundamental wave analysis method, this paper analyzes the working principle of LCC/S+L resonant topology. Then the control strategy of the phase shift angle between bridges and within bridges is obtained by the voltage of both ends of the series inductor and the load voltage vector. It is verified by simulation that the proposed new resonance topology and control strategy can achieve output voltage regulation of 300-500 V with a constant 375 V input DC voltage.

Comprehensive wave-to-wire model and control strategy design for wave energy conversion system

Considering the practical application of wave energy generation, a comprehensive wave-to-wire (W2W) model is proposed in this paper. A novel wave energy conversion (WEC) system with a center of gravity adjustment mechanism is proposed. The proposed W2W model involves the coupling modeling between the absorber and the center of gravity adjustment mechanism as well as the coupling modeling between the absorber and the power take-off (PTO) system. Based on the coupling relationship between the absorber and the center of gravity adjustment mechanism, a resonance control strategy is proposed. In addition, based on the coupling relationship between the absorber and the PTO system, an impedance-matching control strategy is proposed. Combined with the above two control strategies, the two conditions of optimal power capture can be met at the same time, so the WEC system can realize the maximum power point tracking (MPPT). In addition, in order to ensure the safe operation of the WEC system under extreme wave conditions, a power constraint control strategy is proposed to constrain the absorbed power. Finally, the feasibility of the W2W model and the accuracy of the proposed control strategies are verified under the regular and irregular waves.

Disturbance observer‐based quasi‐proportional resonant composite control strategy for high‐frequency LCLC inverters

SummaryA quasi‐proportional resonant (QPR) composite control strategy based on disturbance observer (DOB) is proposed to improve the power quality and dynamic performance of the high‐frequency AC distribution system source side. The load DOB normalizes the controlled object while suppressing the load disturbance and improving the system's robustness and dynamic performance of the system. The QPR control strategy is proposed based on the internal mode principle, which improves the tracking capability of the system for the operating frequency band signal, reduces the system output steady‐state error, and suppresses the inverter output voltage harmonics. To adapt to the high bandwidth requirement of the controller for high‐frequency AC inverters, the proposed control strategy based on analogy devices implementation circuit is designed, and the corresponding controller parameters design method is given. Compared with the traditional control strategy, the proposed control strategy can reduce the inverter output voltage harmonics, effectively suppress the load disturbance, and improve the dynamic performance and steady‐state performance of the system. Finally, the experimental platform verifies the feasibility and effectiveness of the proposed control strategy and the designed circuit.

Research on Harmonic Mitigation Strategy of Static VAR Generator Based on Frequency Adaptation

Offshore wind farms are integrated into the power grid via AC submarine cables, which may cause severe harmonic problems and reduce the power quality of the grid. To address the problem of excessive harmonics in offshore wind power plants (WPPs), this paper proposes a method applying the static var generator (SVG) with frequency adaptive harmonic mitigation function to the offshore WPPs. Firstly, the SVG model and the mechanism of harmonic mitigation are investigated. Secondly, the proportional and resonant control strategy is proposed according to the internal model theorem and applied to the voltage control loop of SVG. The harmonic suppression performance of SVG is studied through the Bode diagram. Thirdly, to adapt to the uncertainty of harmonic frequencies, the recursive least-squares method is introduced to realize the real-time tracking of harmonic frequencies. And the harmonic compensation bandwidth of the SVG is broadened by adjusting the parameters of the controller. Finally, the offshore WPPs in Jiangsu are built based on the Matlab/Simulink platform to verify the effectiveness of the mitigation strategy. Compared with the LC filter, the improved method can effectively mitigate (inter-) harmonics and has strong robustness and adaptability.

Study on the high-frequency resonant control strategy of VSC-HVDC connected into system

It is analyzed that the 1.8 kHz high frequency resonant generated by E side connected to the AC grid in the Yu to E VSCHVDC south channel project. The impedance model of converter is established by converter mathematical analysis. The AC line impedance model is established by frequency scanning method and then mathematical fitting. The Nyquist stability criterion is applied to determine whether the E side meets the conditions for generating high-frequency resonant. The converter impedance with a second-order low-pass filter or a nonlinear filter attached to the feedforward voltage link are analyzed and calculation by MATLAB. At the intersection point of the converter and the AC line impedance amplitude frequency characteristics, if the phase difference at the intersection point does not exceed 180°, the VSC-HVDC system is stability. The high frequency resonance suppression strategy and the inner loop current dynamic control strategy proposed are analyzed in depth. The electromagnetic transient model of Yu to E VSC-HVDC south channel was established with PSCAD software and verified by time-domain simulation. The simulation results show that the dynamic characteristics such as power step response and AC line fault passing through meet the requirements of the technical specification, and guarantee the system stability operation.

Nonlinear dynamics and static bifurcations control of the 12-pole magnetic bearings system utilizing the integral resonant control strategy

In this study, the Integral Resonant Controller (IRC) is presented along with the Proportional-Derivative (PD) controller as a novel control technique to control the dynamical behaviors of the 12-pole rotor active magnetic bearing system. According to the proposed control strategy, the system model has been derived as a two-degree-of-freedom nonlinear dynamical system coupled with two first-order filters. The obtained mathematical model has been analyzed utilizing the asymptotic analysis. The nonlinear algebraic system that governs the steady-state vibration amplitudes and corresponding phase angles of the considered system has been extracted. The influence of the IRC control parameters on the rotor dynamics has been explored by plotting the different bifurcation diagrams. The analytical investigations demonstrated that the vibration suppression efficiency of the combined controller (i.e., PD and IRC) is proportional to the product of control and feedback gains of the IRC as well as the derivative gain of the PD-controller. In addition, it is found that the controller efficiency is inversely proportional to both the square of the internal loop feedback gain of the IRC and the position gain of the PD-controller. Accordingly, an objective function has been derived to design the best control gains of the proposed controller strategy. The analytical and numerical simulations confirmed that the suggested control method can suppress the system vibration and eliminate the catastrophic bifurcation behaviors if the control gains are selected according to the proposed objective function. Finally, the effect of failing one of the coupled integral resonant controllers on the rotor dynamics has been explored as a precautionary procedure. It is found that the failure of one of the coupled integral resonant controllers may breakdown the bifurcation symmetry of the rotor system, but the system does not lose its stability.

Comparative Study of Discrete PI and PR Controller Implemented in SRG for Wind Energy Application: Theory and Experimentation

The Switched Reluctance Generator (SRG) has been widely studied for Wind Energy Conversion Systems (WECS). However, a major drawback of the SRG system adopting the conventional control is the slow response of the DC link voltage controller. In this paper, a Proportional Resonant (PR) control strategy is proposed to control the output voltage of the SRG system to improve the fast response. The SRG model has a high non-linearity, which makes the design of controllers a difficult task. For this reason, the important practical engineering aspect of this work is the role played by the SRG model linearization in testing the sensitivity of the PR controller performance to specific parameter changes. The characteristics of steady-state behaviors of the SRG-based WECS under different control approaches are simulated and compared. The controller is implemented on a digital signal processor (TMS320F28379D). The experimental results are carried out using a 250 W 8/6 SRG prototype to assess the performance of the proposed control compared with the traditional Proportional Integral (PI) control strategy. The experimental results show that the PR control enhances the steady-state performance of the SR power generation system in WECS. Compared to PI control, the rise and settling times are reduced by 45% and 43%, respectively, without an overshoot.

Quantum computation protocol for dressed spins in a global field

Spin qubits are contenders for scalable quantum computation because of their long coherence times demonstrated in a variety of materials, but individual control by frequency-selective addressing using pulsed spin resonance creates severe technical challenges for scaling up to many qubits. This individual resonance control strategy requires each spin to have a distinguishable frequency, imposing a maximum number of spins that can be individually driven before qubit crosstalk becomes unavoidable. Here we describe a complete strategy for controlling a large array of spins in quantum dots dressed by an on-resonance global field, namely, a field that is constantly driving the spin qubits, to dynamically decouple from the effects of background magnetic field fluctuations. This approach---previously implemented for the control of single electron spins bound to electrons in impurities---is here harmonized with all other operations necessary for universal quantum computing with spins in quantum dots. We define the logical states as the dressed qubit states and discuss initialization and readout utilizing Pauli spin blockade, as well as single- and two-qubit control in the new basis. Finally, we critically analyze the limitations imposed by qubit variability and potential strategies to improve performance.

Power Quality Improvement through a UPQC and a Resonant Observer-Based MIMO Control Strategy

Performance degradation is, in general, regarded as a power quality problem. One solution to recover grid performance is through the application of a unified power quality conditioner (UPQC). Although these devices are multi-input/multi-output (MIMO) systems, the most common control strategies consist of two decoupled controllers, which neglect the coupling effects and add uncertainty to the system. For this reason, this paper proposes a multivariable resonant observer-based control strategy of a UPQC system. This method includes all significant coupling effects between this system and the grid. This strategy results in a stability-based compensator, which differs from recently proposed strategies that are based on signal calculation and cannot assure closed-loop stability. In addition, this paper introduces a simplified controller tuning strategy based on optimal conventional methods without losing closed-loop performance. It implies that the controller can be easily tuned, despite the complexity of the MIMO dynamic model. The UPQC with the resonant observer is verified on an experimental setup for a single-phase system, obtaining three relevant results for power quality improvement: (1) harmonics compensation tested with a total harmonic distortion limit of 5%; (2) sags and swells mitigation; and (3) power factor correction, achieving a unitary value on the grid side.

Grid-connected inverter based on proportional resonant control strategy

Grid-connected inverter based on proportional resonant control strategy

Torque Ripple Suppression of PMSM Based on Robust Two Degrees-of-Freedom Resonant Controller

This paper concentrates on a robust resonant control strategy of a permanent magnet synchronous motor (PMSM) for electric drivers with model uncertainties and external disturbances to improve the control performance of the current loop. Firstly, to reduce the torque ripple of PMSM, the resonant controller with fractional order (FO) calculus is introduced. Then, a robust two degrees-of-freedom (Robust-TDOF) control strategy was designed based on the modified resonant controller. Finally, by combining the two control methods, this study proposes an enhanced Robust-TDOF regulation method, named as the robust two degrees-of-freedom resonant controller (Robust-TDOFR), to guarantee the robustness of model uncertainty and to further improve the performance with minimized periodic torque ripples. Meanwhile, a tuning method was constructed followed by stability and robust stability analysis. Furthermore, the proposed Robust-TDOFR control method was applied in the current loop of a PMSM to suppress the periodic current harmonics caused by non-ideal factors of inverter and current measurement errors. Finally, simulations and experiments were performed to validate our control strategy. The simulation and experimental results showed that the THDs (total harmonic distortion) of phase current decreased to a level of 0.69% and 5.79% in the two testing environments.

Torque Ripple Suppression of PMSM Using Fractional-Order Vector Resonant and Robust Internal Model Control

Periodic torque ripples caused by current harmonics seriously affect the control accuracy of the Permanent magnet synchronous motors (PMSMs). A conventional approach to reducing current harmonics is the use of a proportional-integral resonant controller in the current loop. Nonetheless, harmonics can still cause steady-state errors. Furthermore, the PI-based control structure is sensitive to parameter mismatches and uncertain disturbances, which will decrease the tracking performance of the current loop. To overcome the drawbacks of the traditional control method, a hybrid robust resonant control strategy was developed in this study. First, a vector resonant controller was enhanced by introducing fractional-order calculus (denoted as the fractional-order vector resonant (FOVR) controller in this article) so that it can suppress harmonic components more effectively. Then, a robust internal mode controller (Robust-IMC) was designed to improve the robustness and dynamic response and further reduce the current harmonics. Finally, by combining the FOVR controller and Robust-IMC, a control method-FOVR-Robust-IMC was designed as the robust control law to ensure satisfactory robustness and harmonics suppression performance. Meanwhile, the stability and robust stability of the developed control strategy were also analyzed. The results demonstrated that the proposed FOVR-Robust-IMC effectively reduced the harmonic components and improved the robustness to parameter mismatch.

Performance analysis of shunt active filter for harmonic compensation under various non-linear loads

Abstract This paper shows the motivation towards the development of a dq-Proportional Resonant (PR) control strategy in shunt active power filter design for eliminations of distortions in source currents for different loading conditions. The switching signals for the inverter of shunt active power filter (APF) have been generated by the hysteresis current control scheme. The controller performance has been verified by using different types of loads such as non-linear balanced, unbalanced and variable etc., with the system in MATLAB/Simulink environment. An experimental prototype has also been developed in the laboratory and results are analyzed to validate the efficacy of the proposed controller.

Research on Parallel Control Technology of Three-phase Inverter Based on Multiple Proportional Resonance Controller

The parallel operation of multiple inverters can increase the fault tolerance of the system and prevent the occurrence of major accidents. At the same time, it also has strong flexibility, which can reduce the volume and weight of the system and increase the capacity of the system, which is very attractive in the application of uninterruptible power supply. In the inverter parallel system, the circulation will be generated between the inverters due to the existence of the path. Circulation can cause current distortion, reduce system performance, and even damage equipment in severe cases. In order to effectively suppress the generation of circulation, this paper proposes a multiple proportional resonance control strategy for the parallel three-phase inverter system, that is, the voltage outer loop is controlled by PI+PR, and the current inner loop is controlled by PR. Two three-phase inverter parallel systems are built in MATLAB/Simulink simulation environment to compare and analyze the control effect of uncontrolled, traditional PI control and multiple PR control. The simulation results show that the proposed control method has a good suppression effect on the circulation generated in the inverter parallel system, even under the condition of unbalanced load.

Separate-Structure UDE-Based Current Resonant Control Strategy on $LCL$-Type Grid-Tied Inverters With Weighted Average Current Method for Improved Injected Current Quality and Robustness

Due to its effective high-frequency suppression ability, the LCL filter has been widely used between inverters and the grid. However, its resonance causes system instability. The weighted-average current (WAC) strategy has been extensively studied to suppress resonance. By selecting a proper weight factor of the inductor and injected current, the order of the LCL can be reduced to first without resonance in the control loop, which can significantly simplify the controller design. Nevertheless, disturbances and uncertainties in the system will affect the control performance of the inverter. In this article, for a WAC-form LCL grid-tied inverter, a separate-structure uncertainty and disturbance estimator (SUDE) inner-loop control strategy with a zero-phase, low-pass, time-delay FIR filter is designed in the discrete domain to eliminate the influence of disturbances and parameter uncertainties on the system, and a proportional resonant controller is adopted as an outer-loop controller. By using the proposed FIR filter, the performance in the rejection of high-frequency harmonics is improved. Moreover, the stability of the proposed two-degree-of-freedom compound controller is analyzed in detail, and the superiority and effectiveness of its robustness to grid impedance and harmonic rejection are shown. Finally, the proposed strategies are validated on a 2-kW experimental platform.

Dual-Stage Control Structure for Multilevel Voltage Source Inverters

This work proposes an alternative for total harmonic distortion (THD) attenuation in power inverters by combining two different circuit stages. The Macro stage comprises of a Neutral-Point-Clamped (NPC) multilevel inverter operating in high voltage and low switching frequency. The Micro stage is a two-level three-phase inverter, which is faster and more accurate due to its higher frequency and limited voltage. In this dual-stage approach, the opposite characteristics of the converters lead the Micro stage to correct the distortions of the Macro. It is possible to work with small values of filtering components, lower than the ones needed in a one-stage approach. This way, the presented proposal aims to reduce the physical size of the converter and its costs. The NPC inverter works in open loop with its switching signals generated by optimized pulse patterns (OPP). For correct THD filtering, a resonant control strategy with a Notch filter is designed in the frequency domain, as well as a feedforward structure designed in time domain. Simulation results show that the proposed system keeps voltage THD in acceptable levels for IEEE Standards.