摘要 :
Control strategy of a single-phase grid-connected inverter with LCL filter has been a mature research topic. But the most widely-used control method is stationary frame PI (SFPI) current control, which is unable to achieve a unit ...
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Control strategy of a single-phase grid-connected inverter with LCL filter has been a mature research topic. But the most widely-used control method is stationary frame PI (SFPI) current control, which is unable to achieve a unit power factor (PF) and zero steady-state error (SSE) output current. In order to overcome this problem, the synchronous rotating frame PI (SRFPI) control which is widely used in three-phase inverter is applied to the single-phase inverter. This paper first sets up a mathematical model of a SFPI controlled inverter and finds out the relationship between the controller parameters and the inverter output PF and SSE. Then the paper figures out that the output PF and SSE of inverters controlled by SFPI have a maximum value. As comparison, the model of inverter controlled by SEFPI is set up, and a simplified transfer function of the double-inputs double-outputs system of the controller term is obtained to tune the control parameters. Then, the expression of the output PF is derived and proved to be 1 independently of the controller parameters. Finally, simulation and experiment is used to verify the analysis.
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In modeling single-phase full-bridge inverter, instantaneous model with a switching function is generally used to model the power conversion system consisting of switching power poles. However, the equivalent circuit model using a...
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In modeling single-phase full-bridge inverter, instantaneous model with a switching function is generally used to model the power conversion system consisting of switching power poles. However, the equivalent circuit model using a switching function is useful in emulating the response which is close to real power model but it has drawback of steady state response in designing the controller due to limited bandwidth of the control system. Thus, in design the control system of power converter, d-q based model in synchronous rotating frame has been used to model the power conversion system. Nevertheless, the d-q model of power conversion system cannot emulate and reflect the switching characteristics caused by modulation in conventional. Therefore, this paper proposes the macromodel of single-phase full-bridge inverter considering the unipolar switching in synchronous rotating frame. The proposed macromodel of this paper enables d-q inverter model to present the influence of PWM, improving the accuracy of inverter system. This study has been demonstrated by mathematical model and PSIM simulation.
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Tins paper deals with the stability analysis of symmetrical induction motor. The symmetrical induction machine may become unstable over a range of frequencies even though the machine operates from a balanced, sinusoidal, zero impe...
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Tins paper deals with the stability analysis of symmetrical induction motor. The symmetrical induction machine may become unstable over a range of frequencies even though the machine operates from a balanced, sinusoidal, zero impedance source. Small displacement equations valid for small excursions about an operating point are established from the machine equations expressed in synchronously rotating reference frame. Because the resulting equations are linear, any of the conventional techniques may be applied to establish system stability. This paper presents the use of conventional techniques for symmetrical induction machine in synchronously rotating reference frame. The regions of unstability may vary with parameter variation. The machine parameters are affected by variation of temperature and saturation level of the machine. The need for increased accuracy demands a computing model that takes the variation in the parameter during the starting point. This study shows the stability analysis with the parameter variation and effect of parameter variation on stability.
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A synchronous reference frame (SRF) based demodulation strategy for the rotating HF signal injection scheme estimating the rotor position of the interior permanent magnet synchronous motor (IPMSM) is proposed in this paper, allowi...
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A synchronous reference frame (SRF) based demodulation strategy for the rotating HF signal injection scheme estimating the rotor position of the interior permanent magnet synchronous motor (IPMSM) is proposed in this paper, allowing the delays introduced both by the digital controller and by the filters being compensated no matter at a standstill or in rotation. The rotating HF voltages, as standard practices, are injected still in the stationary reference frame, while the carrier currents are extracted in the estimated rotor position oriented reference frame, in which the positive and negative sequence components of the currents pulsates in the same frequency, independent of the rotor speed. As a result, the delaying effects would produce the same phase deviations to both sequence components, providing an ideal conditions to compensate the overall phase error in the negative-sequence component using the positive-sequence, otherwise, the compensation would be degraded as the rotor speed increases. Consequently, the accuracy of the estimated rotor position is enhanced comparing to the conventional demodulation strategies. The effectiveness of the scheme is confirmed through experiments.
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摘要 :
In order to improve the efficiency of three-phase LCL grid-connected inverter, a flexible harmonic current control strategy is proposed in this paper by introducing the functionality of harmonic compensation into the inverter. The...
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In order to improve the efficiency of three-phase LCL grid-connected inverter, a flexible harmonic current control strategy is proposed in this paper by introducing the functionality of harmonic compensation into the inverter. The proposed control strategy consists of two loops: the outer grid current loop and the inner capacitive current loop. Moreover, the outer current loop consists of two parallel control branches: the fundamental current control branch and the harmonic current control branch, adopting different control methods in sychronous rotating frame to achieve decoupling control for fundamental and harmonic component of the inverter's output current, respectively. In addition, the harmonic current control branch can operate in two modes: the harmonic suppression mode and the harmonic compensation mode. The grid-connected inverter can flexibly switch the modes from one to another according to its own capacity and control objectives. Therefore, the proposed strategy can realize effective compensation for local harmonic current and weaken the negative impact of background harmonic voltage on output current without harmonic detection. This paper deduces the stationary frame equivalent universal expression of the controller in synchronous rotating frame and analyzes the control performance of the proposed strategy by using frequency-domain method. The simulation and experimental results verify the feasibility and effectiveness of the strategy.
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摘要 :
In order to improve the efficiency of three-phase LCL grid-connected inverter, a flexible harmonic current control strategy is proposed in this paper by introducing the functionality of harmonic compensation into the inverter. The...
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In order to improve the efficiency of three-phase LCL grid-connected inverter, a flexible harmonic current control strategy is proposed in this paper by introducing the functionality of harmonic compensation into the inverter. The proposed control strategy consists of two loops: the outer grid current loop and the inner capacitive current loop. Moreover, the outer current loop consists of two parallel control branches: the fundamental current control branch and the harmonic current control branch, adopting different control methods in sychronous rotating frame to achieve decoupling control for fundamental and harmonic component of the inverter's output current, respectively. In addition, the harmonic current control branch can operate in two modes: the harmonic suppression mode and the harmonic compensation mode. The grid-connected inverter can flexibly switch the modes from one to another according to its own capacity and control objectives. Therefore, the proposed strategy can realize effective compensation for local harmonic current and weaken the negative impact of background harmonic voltage on output current without harmonic detection. This paper deduces the stationary frame equivalent universal expression of the controller in synchronous rotating frame and analyzes the control performance of the proposed strategy by using frequency-domain method. The simulation and experimental results verify the feasibility and effectiveness of the strategy.
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摘要 :
In order to improve the efficiency of three-phase LCL grid-connected inverter, a flexible harmonic current control strategy is proposed in this paper by introducing the functionality of harmonic compensation into the inverter. The...
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In order to improve the efficiency of three-phase LCL grid-connected inverter, a flexible harmonic current control strategy is proposed in this paper by introducing the functionality of harmonic compensation into the inverter. The proposed control strategy consists of two loops: the outer grid current loop and the inner capacitive current loop. Moreover, the outer current loop consists of two parallel control branches: the fundamental current control branch and the harmonic current control branch, adopting different control methods in sychronous rotating frame to achieve decoupling control for fundamental and harmonic component of the inverter's output current, respectively. In addition, the harmonic current control branch can operate in two modes: the harmonic suppression mode and the harmonic compensation mode. The grid-connected inverter can flexibly switch the modes from one to another according to its own capacity and control objectives. Therefore, the proposed strategy can realize effective compensation for local harmonic current and weaken the negative impact of background harmonic voltage on output current without harmonic detection. This paper deduces the stationary frame equivalent universal expression of the controller in synchronous rotating frame and analyzes the control performance of the proposed strategy by using frequency-domain method. The simulation and experimental results verify the feasibility and effectiveness of the strategy.
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摘要 :
Synchronization control is of great importance for grid-connected power converters, therefore precise phase angle information of the grid voltage is essential. SRF-PLL aims to track the fundamental frequency positive sequence with...
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Synchronization control is of great importance for grid-connected power converters, therefore precise phase angle information of the grid voltage is essential. SRF-PLL aims to track the fundamental frequency positive sequence with zero steady state error. The moving average filter (MAF) is used to eliminate the disturbances of phase error, which is set in-loop of PLL in dq rotate frame. Due to additional time constant induced by MAF, the transient response of the MAF-SRF-PLL is slow. In this paper, a digital effective lead comb compensator cascaded with MAF is proposed to improve the dynamic response. The simulation by using Matlab/Simulink is made to verify the validity and effectiveness. Experiments results are also presented and the comparison with conventional MAF-SRF-PLL verified that the dynamic performance can be significantly improved.
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摘要 :
Synchronization control is of great importance for grid-connected power converters, therefore precise phase angle information of the grid voltage is essential. SRF-PLL aims to track the fundamental frequency positive sequence with...
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Synchronization control is of great importance for grid-connected power converters, therefore precise phase angle information of the grid voltage is essential. SRF-PLL aims to track the fundamental frequency positive sequence with zero steady state error. The moving average filter (MAF) is used to eliminate the disturbances of phase error, which is set in-loop of PLL in dq rotate frame. Due to additional time constant induced by MAF, the transient response of the MAF-SRF-PLL is slow. In this paper, a digital effective lead comb compensator cascaded with MAF is proposed to improve the dynamic response. The simulation by using Matlab/Simulink is made to verify the validity and effectiveness. Experiments results are also presented and the comparison with conventional MAF-SRF-PLL verified that the dynamic performance can be significantly improved.
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摘要 :
It is vital to track voltage phase to synchronization control for grid connected power converters. As three-phase grid voltages distorted seriously, the PD output of SRF-PLL contains disturbances oscillating at integer multiples o...
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It is vital to track voltage phase to synchronization control for grid connected power converters. As three-phase grid voltages distorted seriously, the PD output of SRF-PLL contains disturbances oscillating at integer multiples of fundamental, which introduced steady error of fundamental frequency positive sequence detected angle. To solve this problem, two types of filters set in-loop SRF-PLL, MAF and CDSC, have been well addressed in this paper. These two filters have equivalent effect, if certain conditions hold. Mathematical derivation verifies that the frequency responses of the filters are same. Besides, Loop Filter parameter tune process is similar with each other. The simulation has been carried out by Matlab/Simulink, and test results show that transient processes with these different filters are identical under all kinds of harmonics.
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