The overall control block diagram of the three-phase L-filter grid-connected inverter is shown in Figure 1. Among them, eabc and iabc represent the three-phase grid voltage and grid current, Udc is the DC bus voltage, and Ldbc is the grid-side inductance., iαβ is the component of the three-phase grid side current in the two-phase static αβ coordinate system, id*, iq* are […]
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The previous article analyzed the analysis and improvement of leakage current analysis model, leakage current suppression methods and various topologies based on single-phase non-isolated photovoltaic grid-connected inverters, but the summarized leakage current model and suppression approach can also be analogized to a three-phase grid-connected inverter. Topology using inhibitory pathway A 1. Add an isolation transformer Like […]
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From the previous analysis, it is known that the suppression approach A is to increase the common-mode loop impedance and reduce the high-frequency leakage current in the case of high-frequency changes in the common-mode voltage. The suppression pathways B and C eliminate the high-frequency voltage of the common-mode loop to eliminate the leakage current. Compared […]
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1. Half-bridge inverter topology In Figure 1, if the bridge arm 1 is a capacitor branch and the bridge arm 2 is a power tube, it constitutes a single-phase half-bridge inverter circuit. The driving logic is shown in Figure 3, that is, the upper and lower tubes of the bridge arm 2 are turned on […]
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1. Adopt bipolar SPWM full-bridge inverter Commonly used SPWM strategies for single-phase full-bridge grid-connected inverters include unipolar SPWM, unipolar frequency doubling SPWM and bipolar SPWM. Since the unipolar SPWM strategy has many combinations, the table shows that the upper and lower tubes of the bridge arm 1 in Figure 1 are high-frequency tubes, and the […]
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1. Heric change topology 1 Figure 1 shows a non-isolated topology based on the Heric structure. This topology moves a freewheeling switch in the Heric topology to a group of bridge arms. Using the unipolar SPWM strategy shown in Figure 2, in the power transmission stage, current flows through S3-S2 (positive direction) and S1-S5-S4 (negative direction); In […]
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1. H5 change topology 1 Figure 1 is a circuit structure of a six-switch non-isolated inverter, using the unipolar SPWM strategy shown in Figure 2. This topology adds a switch tube based on the H5 topology. In the power transmission phase, current flows through S5-S1-S4 (positive direction) and S6-S2 (negative direction); in the freewheeling phase, the current flows […]
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1. H5 topology Figure 1 is SMA SoLdr’s patented topology-H5 topology [8], this topology has a switch S5 in series in the main loop of the full bridge circuit. The H5 topology uses unipolar SPWM modulation, and its driving logic diagram is shown in Figure 2. In the power transmission phase, current flows through S5-S1-S4 (positive direction) and […]
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At present, a large number of photovoltaic power generation systems are used in homes and other roofs, and the power is usually 1~50kW. When the photovoltaic grid-connected system does not contain a transformer, the distributed capacitance of the solar panel to the ground provides a low-impedance loop for the common-mode current (Figure 1), where iCM and […]
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Overview The photovoltaic power generation system is usually composed of a battery panel array and a power conversion part (inverter). Placing a low-frequency isolation transformer between the inverter and the grid can achieve electrical isolation between the grid and the photovoltaic array, ensure personal safety, and achieve voltage matching and suppression of the DC component […]
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