Device for testing reliabilities of photovoltaic grid-connected inverters

Abstract

The invention relates to a device for testing the reliabilities of photovoltaic grid-connected inverters, which comprises a three-phase mains supply input module, a single-phase rectifiers, b photovoltaic grid-connected inverters to be tested, c single-phase rectifiers, d photovoltaic grid-connected inverters to be tested, e single-phase rectifiers and f photovoltaic grid-connected inverters to be tested. A, b, c, d, e and f are natural numbers which are not equal to zero. According to the invention, a three-phase four-wire system AC (Alternate Current) power supply is adopted to supply power; a DC (Direct Current) voltage is isolated by a working frequency isolation transformer; a simple full-wave rectification technology is used; the phase difference of each phase of voltage of the three-phase power supply is utilized to effectively inhibit DC input end ripple currents of the photovoltaic grid-connected inverters; and meanwhile, the circuit is simple, the cost is low, the efficiency is high and the reliability is high.

Description

technical field [0001] The invention relates to a reliability test of a photovoltaic grid-connected inverter, and in particular is applicable to a reliability test device for multiple photovoltaic grid-connected inverters. Background technique [0002] When the solar grid-connected inverter is in normal use, the input DC terminal is powered by solar panels. However, since solar panels are greatly affected by the weather, the energy is difficult to control, so a programmable DC power supply is generally used as the power supply for solar grid-connected inverters when developing inverters or experiments. Although the programmable DC power supply has comprehensive functions, it has high cost, low reliability, complex control and large loss. Especially in the batch reliability test of inverters, since each inverter needs to perform maximum power tracking (MPPT), multiple programmable DC sources are required for power supply, which requires a lot of effort in terms of energy con...

AI Technical Summary

Problems solved by technology

Since the bus voltage is at the low point of the valley, the boost control will be strengthened, and the boost duty ratio D will be increased to stabilize the bus voltage. When the boost switch tube is turned on, according to the calculation formula U of the boost inductor current L =L*ΔI L / Δt, where U L =U DC , Δt=D*T (T is the high-frequency switching period of the boost switch tube), U L Increase, Δt increases, it will lead to ΔI at the same time L greatly increase

ΔI L After the increase, the inductance will decrease, that is, L will become smaller, which in turn will continue to cause ΔI L greatly increase

Therefore, the input ripple current of the solar grid-connected inverter is very large, and it is easy to damage the inverter

For non-isolated grid-connected inverters, the general DC source will also increase the leakage current to the ground, which poses a safety hazard

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