Sep.2023 30
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What is the working principle and function of photovoltaic inverters?_SOLARCARRY
What is the working principle and function of photovoltaic inverters?

Working principle of photovoltaic inverter:

       An inverter is a power adjustment device composed of semiconductor devices, mainly used to convert DC power into AC power. It is generally composed of a boost circuit and an inverter bridge circuit. The boost circuit boosts the DC voltage of the solar cell to the DC voltage required for inverter output control, while the inverter bridge circuit equivalently converts the boosted DC voltage into the commonly used frequency AC voltage. The inverter is mainly composed of switching elements such as transistors. By regularly repeating the ON-OFF process of the switching elements, the DC input is transformed into an AC output. Of course, the inverter output waveform generated solely by the on and off circuits is not practical. Generally, high-frequency pulse width modulation (SPWM) is needed to narrow the voltage width near the two ends of the sine wave, and the voltage width at the center of the sine wave is widened, And always operate the switching element in one direction at a certain frequency within half a cycle, forming a pulse train (quasi sine wave). Then let the pulse wave pass through a simple filter to form a sine wave

The role of photovoltaic inverters:

1. Maximum power tracking function

The current and voltage of solar panels vary with the intensity of solar radiation and the temperature of the solar cell components themselves, so the output power also varies. To ensure maximum output power, it is necessary to obtain the maximum output power of the solar panel as much as possible. The MPPT tracking function of the inverter is designed for this characteristic.

2. Anti standalone operation function

The inverter cluster is generally equipped with anti islanding devices. When the grid voltage is 0, the inverter will stop working. The main reason for doing so is for the safety of the power grid. 3. From
After sunrise in the morning, the solar radiation intensity gradually increases and the output of the solar cell also increases. When the output power required for inverter operation is reached, the inverter will automatically start running. After entering operation, the inverter constantly monitors the output of the solar cell module. As long as the output power of the solar cell module is greater than the output power required for the inverter to work, the inverter will continue to operate; Until sunset, the inverter can operate even on rainy days. When the output of the solar cell module decreases and the inverter output approaches 0, the inverter forms a standby state.

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