Single-Phase Grid-Connected Motor Drive System With DC-Link Shunt Compensator and Small DC-Link Capacitor
TL;DR: In this paper, a dc-link shunt compensator (DSC) was proposed to improve the performance of a single-phase diode rectifier with small DC-link capacitors.
Abstract: The single-phase diode rectifier system with small dc-link capacitor shows wide diode conduction time and it improves the grid current harmonics. By shaping the output power, the system meets the grid current harmonics regulation without any power factor corrector or grid filter inductor. However, the system has torque ripple and suffers efficiency degradation due to the insufficient dc-link voltage. To solve this problem, this paper proposes the dc-link shunt compensator (DSC) for small dc-link capacitor systems. DSC is located on dc-node in parallel and operates as voltage source, improving the system performances. This circuit helps the grid current-shaping control during grid-connection time, and reduces the flux-weakening current by supplying the energy to the motor during grid-disconnection time. This paper presents a power control method and the design guideline of DSC. The feasibility of DSC is verified by simulation and experimental results.
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TL;DR: In this paper, an inverter power control strategy based on dc-link voltage regulation for the electrolytic capacitor-less interior permanent magnet synchronous motor drive system was proposed, which achieved high input power factor and low grid current harmonics.
Abstract: DC-link electrolytic capacitor critically affects the lifetime of the motor drive system. This paper proposes an inverter power control strategy based on dc-link voltage regulation for the electrolytic capacitor-less interior permanent magnet synchronous motor drive system. The dc-link electrolytic capacitor is replaced by a small film capacitor and the power factor correction circuit is also eliminated. Hence, the inverter power should be regulated effectively to achieve high input power factor and low grid current harmonics. The inverter power control loop based on proportional resonant (PR) controller is established to regulate the inverter power into sinusoidal wave. The PR controller can be designed to achieve a high gain at the desired frequency and the parameters are easy to design due to the simple structure. In addition, a power compensation method based on the dc-link voltage regulation is used to diminish the error of inverter power control, which does not depend on the precise calculation and is easy to realize. The effectiveness of the proposed method is demonstrated by the experimental results on an air conditioner. The input power factor can reach 0.992 and the harmonics of grid current are considerably lower than the requirement of EN61000-3-2 standard.
68 citations
Cites methods from "Single-Phase Grid-Connected Motor D..."
...A dc-link shunt compensator (DSC) for the small dc-link capacitor system was applied in [25]....
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TL;DR: In this paper, a power decoupling approach using a four-switch three port DC/DC/AC converter in a DC microgrid is described, where the power flow control technique is used so that the converter is decoupled to obtain low frequency ripple power.
Abstract: Power maintenance in a real time microgrid plays an important role in today's scenario. This paper describes a power decoupling approach using a four-switch three port DC/DC/AC converter in a DC microgrid. The system is designed with three topologies connected with a DC source, a capacitor and an AC port. The power flow control technique is used so that the converter is decoupled to obtain low frequency ripple power. The system is compact and cost effective. The system is designed with two inductors current control. Results show that the described topology is feasible and analyzed the designed power control technique.
45 citations
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TL;DR: In this article, an active damping method based on the virtual damping resistor is applied to suppress the LC resonance and improve the drive system stability in a reduced dc-link capacitance motor drive system.
Abstract: The LC resonance between the line inductor and the dc-link film capacitor is an important concern in the reduced dc-link capacitance interior permanent magnet synchronous motor drive system. In this paper, an active damping method based on the virtual damping resistor is applied to suppress the LC resonance and improve the drive system stability. The performance of the damping resistor is analyzed in a systematic level, and possible configurations have been analyzed to obtain the optimal solution, which is proved to be the inductor current feedback (ICF) damping method. In order to realize the equivalent damping effect, the dc-link voltage feedback is applied to emulate the ICF-based active damping method by a step-by-step approach. Meanwhile, the grid voltage distortion will stimulate additional harmonics of the grid current in the reduced dc-link capacitance motor drives. Hence a feedforward compensation method is applied to suppress the grid current distortion arising from the distorted grid voltage, which has not been investigated in the previous related researches. Harmonics of the grid current are reduced and requirements of EN61000-3-2 can be satisfied by applying the proposed method. Experiments on a compressor drive platform equipped with the reduced dc-link capacitance are performed to verify the effectiveness of the proposed method.
26 citations
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TL;DR: A novel overmodulation strategy named as the optimized voltage boundary-based overmodulated strategy is proposed to reduce the distortion of the stator voltage and current and demonstrates its effectiveness on a PMSM drive platform.
Abstract: Permanent magnet synchronous motor (PMSM) drives equipped with slim film capacitors have many advantages, including longer lifetime, smaller volume, and lower cost. However, improving the dc-link voltage utilization rate by the typical overmodulation strategy will cause the distortion of the stator voltage and current due to the dc-link voltage fluctuation. In this article, the influence of the dual-mode overmodulation strategy used in the small dc-link capacitor PMSM drive, including the stator voltage distortion and uncontrollable time for entering the six-step operation, is analyzed. A novel overmodulation strategy named as the optimized voltage boundary-based overmodulation strategy is proposed to reduce the distortion of the stator voltage and current. By switching between the actual dc-link voltage and the fixed dc-link voltage used for space vector pulse width modulation (SVPWM), the performance can be improved in the overmodulation region if the value of the dc-link voltage for SVPWM is selected appropriately. Experimental results on a PMSM drive platform are provided to verify the effectiveness of the proposed strategy.
25 citations
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TL;DR: The impedance model of the drive system is established considering the dc-link voltage fluctuation, which is applied to evaluate theDrive system stability and the grid current harmonics issue could also be analyzed by the grid input impedance model.
Abstract: The instability issue is an important concern in the reduced dc-link capacitance motor drive system, which is caused by the interaction of the LC resonance and the negative impedance of the constant power load (CPL). Harmonics of the grid current also need to be concerned to meet the requirement of the application standards. In this paper, the impedance model of the drive system is established considering the dc-link voltage fluctuation, which is applied to evaluate the drive system stability. The grid current harmonics issue could also be analyzed by the grid input impedance model. A novel grid current feedback based stabilization control method is proposed to stabilize the drive system, which could formulate the Nyquist plot of the drive system. Besides, the grid current harmonics could also be suppressed effectively by adopting the proposed stabilization control method. Experimental results are performed to verify the effectiveness of the proposed method.
13 citations
References
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18 Jun 2006TL;DR: In this article, a phase-locked-loop (PLL) method for single-phase systems was proposed to detect the phase angle, amplitude and frequency of the utility voltage.
Abstract: Phase, amplitude and frequency of the utility voltage are critical information for the operation of the grid-connected inverter systems. In such applications, an accurate and fast detection of the phase angle, amplotude and frequency of the utility voltage is essential to assure the correct generation of the reference signals and to cope with the new upcoming standards. This paper presents a new phase-locked-loop (PLL) method for single-phase systems. The novelty consists in generating the orthogonal voltage system using a structure based on second order generalized integrator (SOGI). The proposed structure has the following advantages: — it has a simple implementation; — the generated orthogonal system is filtered without delay by the same structure due to its resonance at the fundamental frequency, — the proposed structure is not affected by the frequency changes. The solutions for the discrete implementation of the new proposed structure are also presented. Experimental results validate the effectiveness of the proposed method.
1,023 citations
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TL;DR: In this article, a ripple power port is proposed to manage energy storage and decouple capacitor ripple from power ripple, allowing the designer to make a choice of capacitor voltage independent of other system voltages.
Abstract: Converters with a dc port and a single-phase ac port must store energy to buffer the inherent double-frequency power flow at the ac port. The minimum energy storage required to isolate the power ripple from the dc port is presented, and leads to the minimum capacitance required for converters that use capacitive energy storage. This paper presents a ripple power port to manage energy storage and decouple capacitor ripple from power ripple. A ripple power port allows the designer to make a choice of capacitor voltage independent of other system voltages. A combination of an ac link converter and a ripple power port leads to a dramatic increase in reliability: it is shown that converters with nominal ratings up to 200 W can be designed with expected mean-time-between-failure ratings on the order of 1.4 × 106 h-sufficient for hundred-year operation in long-life applications such as photovoltaic converters and LED lamps. This large increase in life is achieved with minimal extra cost.
464 citations
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TL;DR: In this paper, a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications is presented, compared and scrutinized in scope of the size of decoupled capacitor, efficiency, and control complexity.
Abstract: The reliability of the microinverter is a very important feature that will determine the reliability of the ac-module photovoltaic (PV) system. Recently, many topologies and techniques have been proposed to improve its reliability. This paper presents a thorough study for different power decoupling techniques in single-phase microinverters for grid-tie PV applications. These power decoupling techniques are categorized into three groups in terms of the decoupling capacitor locations: 1) PV-side decoupling; 2) dc-link decoupling; and 3) ac-side decoupling. Various techniques and topologies are presented, compared, and scrutinized in scope of the size of decoupling capacitor, efficiency, and control complexity. Also, a systematic performance comparison is presented for potential power decoupling topologies and techniques.
458 citations
"Single-Phase Grid-Connected Motor D..." refers background in this paper
...Proposed topologies in [10]–[18] are usually utilized along...
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TL;DR: In this paper, the minimum ripple energy storage requirement is derived independently of a specific topology, and the feasibility of the active capacitor's reduction schemes is verified based on the minimum energy requirement, which can effectively reduce the energy storage capacitance.
Abstract: It is well known that single-phase pulse width modulation rectifiers have second-order harmonic currents and corresponding ripple voltages on the dc bus. The low-frequency harmonic current is normally filtered using a bulk capacitor in the bus, which results in low power density. However, pursuing high power density in converter design is a very important goal in the aerospace applications. This paper studies methods for reducing the energy storage capacitor for single-phase rectifiers. The minimum ripple energy storage requirement is derived independently of a specific topology. Based on the minimum ripple energy requirement, the feasibility of the active capacitor's reduction schemes is verified. Then, we propose a bidirectional buck-boost converter as the ripple energy storage circuit, which can effectively reduce the energy storage capacitance. The analysis and design are validated by simulation and experimental results.
450 citations
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TL;DR: Through a detailed mathematical analysis, it is shown that these two PLL structures are equivalent to each other, from the control point of view, and a linearized model is developed which is valid for both PLLs.
Abstract: Recently, several advanced phase-locked loop (PLL) techniques have been proposed for single-phase applications Among these, the Park-PLL and the second-order-generalized-integrator-based PLL are very attractive, owing to their simple digital implementation, low computational burden, and desired performance under frequency-varying and harmonically distorted grid conditions Despite the wide acceptance and use of these two advanced PLLs, no comprehensive design guidelines to fine-tune their parameters have been reported yet Through a detailed mathematical analysis, it is shown that these two PLL structures are equivalent to each other, from the control point of view Then, a linearized model is developed which is valid for both PLLs The derived model significantly simplifies the stability analysis and the parameter design To fine-tune the PLL parameters, a systematic design approach is suggested afterward, which guarantees a fast dynamic response, a high disturbance rejection ability, and a robust performance Finally, the simulation and experimental results are presented to support the theoretical analysis
312 citations