分切合整控制之單相雙向換流器與太陽能最大功率追蹤器整合

INTEGRATION OF A D-Σ CONTROLLED SINGLE-PHASE BI-DIRECTIONAL INVERTER WITH PHOTOVOLTAIC MAXIMUM POWER POINT TRACKERS

孫堃涵(Kun-Han Sun)

指導教授 ： 張淵智 ； 吳財福

國立中正大學/工學院/電機工程學系/博士(2013年)

摘要

無資料

關鍵字

最大功率追蹤器 ； 單相雙向換流器 ； 分切合整控制

並列摘要

This dissertation presents integration of a division-summation (D-Σ) digital controlled single-phase bi-directional inverter with multiple maximum power point trackers (MPPTs) for dc-distribution applications. Since the PV-array voltage can vary from 100 to 600 V, the topology of the proposed MPPT combines buck and boost converters to accommodate wide PV voltage variation, and to operate at the dc-bus voltage around 380 V. The control algorithm for tracking maximum power points is based on a perturbation and observation method. To determine MPPT input current for maximum power calculation and increase the freedom of PV panel connection, the controller can online check the input configuration of the MPPTs, which can be separate or in parallel connection. Furthermore, the current from the PV arrays can be equally distributed between the MPPT modules based on a uniform current control scheme. A buck/boost mode transition algorithm is also presented to smooth out mode transition.
In dc-distribution applications, the bi-directional inverters can fulfill both grid connection and rectification with power factor correction. The proposed D-Σ control summarizes the inductor-current variations over one switching cycle to derive control laws directly. With the proposed control, the inverter can track its sinusoidal reference currents, and it is allowed to have wide inductance variation, reducing core size significantly. In the design and implementation, the inductances corresponding to various inductor currents are measured and tabulated into a single-chip microcontroller for tuning loop gain cycle by cycle, ensuring system stability.
For applying to dc distribution systems, the bi-directional inverter is required to control the power flow between dc bus and ac grid, and to regulate the dc bus to a certain range of voltages. A one line-cycle regulation approach is proposed, which is based on a linear power management scheme to balance power flow and accommodate load variation. The approach takes dc-bus capacitance into account and control dc-bus voltage to track a linear relationship between the dc-bus voltage and inverter inductor current. With this regulation mechanism, the inverter tunes the dc-bus voltage every line cycle, which can reduce the frequency of operation-mode change and current distortion. Simulation and experimental results from a 5 kW system have verified the feasibility of the proposed control approaches and the discussed features.

並列關鍵字

maximum power point tracker ； single-phase bi-directional inverter ； D-Σ control

參考文獻

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