Quasi-proportional Resonant Controller Research Articles

Research on current harmonic suppression of permanent magnet synchronous motor using smith predictive controller

Abstract Due to the dead time added to the operation of the motor inverter, the generated current harmonics are introduced into the synchronous motor, increasing the harmonic content of the motor. The higher harmonic content is the 5th, 7th, 11th, and 13th current harmonics, which can cause motor torque ripple [1]. To suppress the current harmonics that cause torque ripple, a control method of using a PI controller and a quasi-proportional resonant controller in parallel is considered to suppress current harmonics. However, the introduction of a proportional resonant controller can cause greater overshoots in the current response, and external environmental influences can also generate current disturbances. Therefore, a method based on Smith prediction-PID and quasi-proportional resonance controller cascade control structure is proposed to suppress current harmonics and current overshoot in response to this problem. Finally, the effectiveness of this method was verified through simulation experiments, thereby improving the stability of synchronous motor operation.

Research on VIENNA rectifier QPR control and soft start

The principle and operation of the VIENNA rectifier is examined and the VIENNA mathematical model is developed. To address the issue that the three-phase VIENNA rectifier’s double PI controller finds it challenging to attain both rapidity and accuracy, a double closed-loop control approach consisting of inner loop quasi-proportional resonant control (QPR) and outer loop PI control is created. Aiming at the problems of inrush current on the grid side and DC bus voltage overshoot caused by the VIENNA rectifier in the startup process, the paper makes a theoretical analysis and designs a soft startup strategy. Then, the simulation model of the three-phase VIENNA rectifier control system was built in Simulink, which verified the correctness of the QPR control strategy and soft start scheme. Finally, an 8-kW prototype is set up, and the experimental results further confirm the effectiveness of the slope setting of the current.

Application of optimized photovoltaic grid-connected control system based on modular multilevel converters

Photovoltaic power generation is a promising method for generating electricity with a wide range of applications and development potential. It primarily utilizes solar energy and offers sustainable development, green environmental benefits, and abundant solar energy resources. However, there are many external factors that can affect the output characteristics of Photovoltaic cells and the effectiveness of the grid-connected control system. This study describes the introduction of Modular Multilevel Converter (MMC) technology into photovoltaic power generation systems to improve power generation efficiency. It proposes optimizing and improving the technology by adjusting the temperature and magnitude of lighting and combining traditional algorithms to propose a composite control algorithm. The photovoltaic power generation system employs the modular multi-level converter technology to enhance power generation efficiency alongside optimization and improvement. The temperature and size of light are regulated alongside the traditional algorithm to introduce the composite control algorithm. The improved composite algorithm surpasses the traditional one after experimental comparison of the results. The testing of a model photovoltaic power grid-connected system shows that the combination of modular multi-level converter technology and a photovoltaic grid-connected system, incorporating composite proportional integral control and quasi-proportional resonant control algorithms, yields improved results and feasibility. With rationality and effective control. The simulation results show that at 0.5 s, the light intensity suddenly increases from 750 to 1000 W/m2, and the direct-current voltage suddenly increases for a short time, but then decreases rapidly and finally returns to a stable level close to the rated voltage. From this, it can be seen that when the light intensity continues to change, the voltage value on the direct-current bus side of this MMC grid-tied photovoltaic system can still be maintained close to the rated value, ensuring the operational stability of the entire system. Sensibly and effectively controlled. The implementation of MMC technology in photovoltaic power generation systems enhances power generation efficiency, whilst simultaneously supporting the advancement of photovoltaic power generation and contributing towards environmental protection in the long term.

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.

Super-Twisting Extended State Observer-Based Quasi-Proportional-Resonant Controller for Permanent Magnet Synchronous Motor Drive System

For the purpose of realizing permanent magnet synchronous motor (PMSM) systems with strong robustness and smooth speed, the quasi-proportional-resonant (QPR) controller is combined with super-twisting extended state observer (STESO) in this paper. Although traditional active disturbance rejection control scheme generally selects a sufficiently large bandwidth of linear extended state observer (LESO) to enhance the time-varying disturbance rejection capacity, the bandwidth of LESO is limited by system stiffness. To solve this tough issue, the STESO using generalized super-twisting technique is developed to optimize the stability and anti-disturbance capacity of motor drive system. In addition, the QPR controller is combined with the proposed STESO to suppress the motor speed fluctuation. Experimental results show that the proposed STESO-based QPR control algorithm has satisfactory characteristics.

A Deadbeat Predictive Current Harmonics Suppression Method for IPMSM Based on Quasi Proportional Resonant Control

A Deadbeat Predictive Current Harmonics Suppression Method for IPMSM Based on Quasi Proportional Resonant Control

Adaptability enhancement of fractional‐order LLCL‐type grid‐connected inverter to weak grid based on grid voltage weighted feedforward scheme

SummaryGrid‐connected inverter with a novel fractional‐order LLCL filter has the advantage of high grid current tracking accuracy and low total harmonic distortion without passive or active dampers, and the grid voltage full feedforward scheme is an effective method to improve the quality of grid current. However, due to the digital control delay, the suppression of the grid current harmonics is weakened, and the inverter output impedance has an additional negative phase shift, which deteriorates the stability of grid‐connected systems under weak grid. In this paper, a weighted grid voltage fractional‐order feedforward control scheme is proposed based on a quasi‐proportional resonant (QPR) controller, which introduces two weighting factors in the full feedforward path of the grid voltage and compensates the phase lag of the output impedance by designing appropriate weighting factors. Then, an improved scheme combining the QPR controller with a phase compensator is presented. As a result, the suppression ability of grid current harmonics and the adaptability to grid impedance variations are enhanced. Simulation and experimental results verify the effectiveness of the proposed grid voltage fractional‐order weighted feedforward scheme.

A Universal Interpretation of Three Types of Resonator-Based Controllers

It is well credited that generalized active disturbance rejection controller (GADRC), proportional resonant controller (PRC) and quasi proportional resonant controller (QPRC) are proficient in suppressing fast varying sinusoidal disturbances or tracking fast varying sinusoidal signals respectively. Establishing the equivalence analysis criterion is beneficial to evaluate or compare the performance of GADRC, PRC and QPRC. Thus, we establish the equivalence analysis criterion by exploring the equivalence among GADRC, PRC and QPRC in the context of the three-phase voltage system. To be more specific, the GADRC, PRC and QPRC can be interpreted as a class of proportional integral integral-integral (PII) controllers with a filter by mathematical reasoning. The equivalence analysis can provide parameter tuning of the three controllers. The differences and similarities among them can be described by ν gap metric and Bode diagrams by MATLAB/Simulink.

The Effects and Mechanisms of Periodic-Carrier-Frequency PWM on Vibrations of Multiphase Permanent Magnet Synchronous Motors

High-frequency vibration and noise induced by pulse width modulation (PWM) deteriorate the acoustic performance of permanent magnet synchronous motor (PMSM) drives. Periodic-carrier-frequency PWM (PCFPWM) is an effective method that can disperse the high-frequency harmonics to a wider frequency band, thereby suppressing the peak harmonic. This paper presents a detailed study on how exactly PCFPWM affects both the low-frequency and high-frequency vibrations of PMSMs. It is revealed that PCFPWM actually deteriorates low-frequency vibrations of the motor, due to unwanted side effect of additional AC components in d- and q-axis currents and thus increased torque pulsations. But this can be remedied by quasi-proportional resonant control of corresponding current harmonics. For high-frequency vibrations, the paper thoroughly studies the effects of PCFPWM on current harmonics and the zero-order electromagnetic (EM) force acting on motor stator teeth. Compared with the experimental vibration results, it is found that high-frequency zero-order EM force is the direct and major cause of EM vibrations induced by PCFPWM. This paper provides the theoretical basis for future optimization of PCFPWM based on the zero-order EM force as a direct vibration metric.

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.

MMC circulating current suppression strategy based on improved quasi-PR control

The internal circulation of modularized multilevel converter will affect waveform quality and increase system loss. In this paper, the basic principle and topological structure of MMC as well as the causes of the internal circulation are briefly analyzed. A method of harmonic component extraction based on the second-order generalized integrator and the suppression strategy of MMC circulation based on feedforward compensation quasi-proportional resonant control are proposed. The feasibility of this strategy is verified in MATLAB/Simulink, and the simulation results show that the circulation and capacitor voltage fluctuation are controlled within a reasonable range.

Adaptive quasi-proportional resonant control with parameter estimation for PMSM sensorless control

Conventional sliding mode control (SMO) utilizes a sign function and a low-pass filter (LPF) to achieve sensorless control of a permanent magnet synchronous motor (PMSM). However, the introduction of the sign function generates a large number of high harmonics, resulting in a significant system output chattering, whereas the addition of the LPF generates control delays and phase shifts. These degrade the PMSM speed and the position estimation accuracy and reduce the system control performance. To improve the performance of the PMSM, adaptive quasi-proportional resonant sensorless control with parameter estimation (AQPR_PE) is proposed. In this control model, an adaptive quasi-proportional resonance controller is used reduce the system output error and to weaken the chattering phenomenon. Meanwhile, the system PMSM parameters are estimated online and fed back to the control model to improve the system parameter robustness and the control accuracy. The Bode diagram, Popov theory, and root trajectory are used to analyze the stability of AQPR, parameter estimation, and AQPR_PE, respectively. Finally, the effectiveness of the proposed method is demonstrated by experimental validation.

Grid-Connected Control Strategy of VSG under Complex Grid Voltage Conditions

Under complex grid conditions, the grid voltage usually has an imbalance, low order harmonics, and a small of DC bias. When the grid voltage contains low order harmonics and a small amount of DC bias component, the inverter's output current cannot meet the grid connection requirements, and there is a three-phase current imbalance in the control strategy of common VSG under unbalanced voltage. A theoretical analysis of non-ideal power grids is carried out, and a VSG control strategy under complex operating conditions is proposed. Firstly, the third-order generalized integrator (TOGI) is used to eliminate the influence of the DC component of grid voltage. An improved delay signal cancellation (DSC) method is proposed to control the balance current and power fluctuation under unbalanced voltage based on the method of common VSG positive and negative sequence separation, It also eliminates the harmonic of command current. Then, the improved quasi proportional resonant controller (QPR) cascaded PI is used to suppress the harmonic current further so that the harmonic content of grid-connected current can meet the grid-connected requirements and achieve the three-phase current balance. Finally, the proposed strategy is verified by simulation under the control objectives of the current balance, active power, and reactive power constant.

An Improved Quasi-Resonant Controller for Grid-Connected Inverter with LCL Filter

Aiming at the problem of insufficient response speed of traditional quasi-resonant controllers in the application of grid-connected inverters with LCL filter, a novel hybrid controller which combines a quasi-proportional resonant controller and an integrator is proposed in this paper. Base on this controller, the stability, the parameter design and the digital time delay compensation of the system are analyzed and designed in detail. Finally, its effectiveness is experimentally verified at Matlab/Simulink. By comparing with the traditional control method, it leads to a conclusion that the novel hybrid controller can maintain the control accuracy while allowing the system have good dynamic performance.

Analysis and verification of harmonic interaction between DDWTs based on αβ stationary coordinate system

This study presents an analysis method of harmonic interaction characteristics between direct-drive wind turbines (DDWTs) based on αβ coordinates and the relative gain array (RGA). First, considering the digital delay of inverters, the capacitive current feedback active damping is applied to suppress the resonance of LCL filter, and the output current of DDWT is regulated by quasi-proportional resonant controller in the αβ coordinates and then combined with the topology of the direct-drive wind farm (DDWF), the transfer function matrix of the DDWF is established. Second, based on the RGA principle, the relationship between parameters and harmonic interaction characteristics is quantitatively analysed. The results show that with the proportional coefficient increasing, the degree of negative interaction between DDWTs is strengthened, which increases the harmonic content in the negative interaction frequency band. However, the increase of resonance coefficient and number of DDWTs will weaken the degree of negative interaction. In addition, with the increase of capacitive current feedback coefficient and grid inductance, the interaction frequency gradually decreases. Finally, the DDWF model is built both on Matlab/Simulink and StarSim + PXI hardware-in-the-loop platform to verify the analytical results. The harmonic interaction characteristics can be used to guide the parameter design of DDWTs, so as to optimise power quality of the wind farm.

Application of Repetitive Control in Electric Spring

With the increasing of the grid-connected capacity of renewable energy such as wind energy and solar energy, its instability, intermittence and uncontrollability have a serious impact on the stable operation of power system, such as voltage fluctuation, frequency flicker, etc. Therefore, Electric Spring (ES) system has become a current research hotspot. Aiming at the deficiencies of the resonance control strategy, a control method that combines quasi-proportional resonance (QPR) control and repetitive control is proposed. The quasi proportional resonance control is used to realize the tracking without static error, and the internal model principle of repetitive control is used to suppress the periodic disturbance of the grid voltage, so as to improve the power quality of the grid. Compared with the traditional quasi proportional resonant control, the introduction of repetitive control can effectively improve the steady-state accuracy, reduce the system harmonic and enhance the ability of anti-harmonic interference. The modeling of ES and the design method of repetitive controller parameters are discussed in detail. The simulation model is built using MATLAB / Simulink, and the ES experimental platform is built with dSPACE as the control core, the results verify the feasibility and effectiveness of the proposed control strategy.

Quasi-Proportional-Resonant Controller Based Adaptive Position Observer for Sensorless Control of PMSM Drives Under Low Carrier Ratio

The position and speed estimation performance of the sliding mode observer (SMO) for permanent magnet synchronous motor (PMSM) drives under low carrier ratio degrades, due to the inherent chattering and enlarged control delay. To improve estimation performance, this paper proposes a quasi-proportional-resonant (QPR) based adaptive observer to obtain back electromotive force with adaptive harmonics cancellation. In this observer, the QPR controller is employed to eliminate errors between the observed currents and the actual ones in the αβ reference frame, replacing sign function and low pass filter (LPF) of the SMO to cancel the chattering, and harmonics immune performance can also be achieved thanks to frequency selection characteristic of the QPR controller. Besides cancelling the chattering, the proposed observer can also eliminate phase shift produced by the LPF, since the QPR controller is a zero phase-shift amplifier at the resonant frequency. Comparative experiments are carried out in a 3-kW PMSM drive, and the results validate the effectiveness of the proposed adaptive position observer.

Quasi proportional‐resonant control for the grid current of hybrid distribution transformer

Hybrid distribution transformer (HDT) has powerful control ability, which is significant for the intelligentisation of the distribution network. A kind of HDT is presented here, the grid current control system of which is emphatic researched. Based on the mathematical model of ideal HDTs, a grid current control system is designed with quasi proportional-resonant controller (QPR). Using the characteristics that infinite gain and large bandwidth at the resonant frequency of QPR controller, the grid current system achieve the effects of unit power factor and sinusoidal symmetrical waveform. Tracking control with no static error of grid current was achieved in MATLAB. Compared with the traditional PI control, QPR controller can modulate AC signals in the static coordinate system, rather than rotary coordinate system. So the QPR controller has advantages of lower steady-state error, stronger anti-interference ability, and simpler calculation. Simulation results show that it has good dynamic and steady performance.

High performance control strategy for single‐phase three‐level neutral‐point‐clamped traction four‐quadrant converters

Operational data from Chinese railways indicate a number of challenges for traction four-quadrant converter (4QC) control including low-order voltage and current harmonics and reference tracking. A control strategy for a single-phase three-level neutral-point-clamped 4QC employed in the electric multiple unit traction system is proposed in this study. The strategy is based on a multiple frequency tuned quasi-proportional resonant controller in the ac-side current loop and a multiple frequency tuned notch filter in the dc-link voltage loop. Under the typical supply voltage distortion present in the network, the proposed control strategy improves the current tracking performance and reduces the line current harmonics, when compared with conventional control strategies. Experimental results, both under purely sinusoidal and distorted supply voltages, validate the effectiveness of the proposed control strategy.

An Active Power Sharing Method among Distributed Energy Sources in an Islanded Series Micro-Grid

Active power-sharing among distributed energy sources (DESs) is not only an important way to realize optimal operation of micro-grids, but also the key to maintaining stability for islanded operation. Due to the unique configuration of series micro-grids (SMGs), the power-sharing method adopted in an ordinary AC, DC, and hybrid AC/DC system cannot be directly applied into SMGs. Power-sharing in one SMG with multiple DESs involves two aspects. On the one hand, capacitor voltage stability based on an energy storage system (ESS) in the DC link must be complemented. Actually, this is a problem of power allocation between the generating unit and the ESS in the DES; an extensively researched, similar problem has been grid-off distributed power generation, for which there are good solutions. On the other hand, power-sharing among DESs should be considered to optimize the operation of a series micro-grid. In this paper, a novel method combining master control with auxiliary control is proposed. Master action of a quasi-proportional resonant controller is responsible for stability of the islanded SMG; auxiliary action based on state of charge (SOC) realizes coordinated allocation of load power among the source. At the same time, it is important to ensure that the auxiliary control does not influence the master action.