MOREDAY Lab: How does an inverter convert DC to AC?

MOREDAY laboratory, help you understand photovoltaic. Today, MOREDAY will work with you to understand the “magic process” of converting direct current into alternating current, and analyze what is the main reason that affects the conversion efficiency of inverters?


What are direct current and alternating current?

The job of the inverter is to convert the direct current generated by the photovoltaic array into alternating current. First, we need to understand what is DC and AC?


·Direct current (DC): The direction of the current and voltage of the direct current is the same, and the direction of the current is always the same. The dry batteries and lead-acid batteries that we commonly use in our daily life use direct current.

·Alternating Current (AC): The direction and magnitude of the alternating current will change periodically over time. The household 220V power supply used in life is AC.

From the difference between direct current and alternating current, we can find that direct current has great limitations in daily applications, for example, AC loads of household appliances cannot be powered by DC power, and long-distance transportation will lose most of the power, etc. Therefore, for photovoltaic power generation to be widely used in our daily life, an inverter that can convert the direct current generated by it into alternating current is indispensable.

How is direct current converted to alternating current?

When the PV array transmits DC power to the inverter, the DC power quickly transfers energy back and forth through the inverter’s internal devices. In the process, the inverter forces the direct current to continuously change direction, producing a square wave alternating current.

However, the square wave AC waveform is not smooth, and the voltage has been changing suddenly, which will seriously affect the life of the appliance.

Therefore, the inverter speeds up the transmission speed and modulates multiple pulses in each sine cycle with a natural or regular width through sinusoidal pulse width modulation (SPWM), so that these pulses are modulated in turn to be equivalent to a sine The pulse sequence of the wave forms a sinusoidal current output, so that the square waveform AC can be successfully converted into a sinusoidal AC, and the purpose of converting DC to AC is achieved.


The conversion efficiency of different inverters varies

It is worth mentioning that although inverters can convert direct current to alternating current, the conversion efficiency varies.

In most cases, factors such as the power loss of the internal components of the inverter will affect the conversion efficiency of the inverter, resulting in changes in the power generation revenue of the photovoltaic power station.

Taking a 500kW inverter as an example, under the same power, if a high-quality inverter has 1% higher conversion efficiency than ordinary inverters, based on the calculation of 4 hours of work per day, the high-quality inverter can emit nearly 20 degrees more per day. Electricity, then nearly 7,300 kWh of electricity can be generated in one year, and 73,000 kWh of electricity can be generated in ten years, which greatly improves the user’s power generation income.

How to choose high conversion rate products among many inverters to maximize the production capacity of photovoltaic power plants?

Taking the MOREDAY inverter as an example, in terms of conversion efficiency, the Hemai micro-inverter system adopts a fully parallel circuit design, which can convert the DC power of each component into AC power and then merge it into the power grid to minimize losses during the inversion process. energy of.


On the other hand, MOREDAY module-level MPPT technology will track the maximum power point of each PV module separately. This means that if a certain photovoltaic module is inefficient, it will not affect other photovoltaic modules. For example, in the entire photovoltaic system, a module is blocked by 50% of the sunlight, and the maximum power point tracking control of other components is at this time. The devices will continue to maintain their maximum capacity efficiency.


In terms of product quality, MOREDAY has strict control over the production process and device quality. It adopts a mature topology scheme in the power supply industry, with reliable structure, sufficient design margin, and a warranty of up to 15 years. The internal glue is filled to enhance the thermal conductivity of the power device to the casing and reduce the internal thermal stress. At the same time, the inverter has been certified by authoritative third-party professional organizations at home and abroad (CQC, TÜV, CSA, etc.), and its performance and quality are trusted by many countries and have a high market recognition.

Do you understand the working principle and conversion efficiency of the inverter? Before choosing an inverter, we need to understand its performance and solutions in advance, so as to better choose an efficient, safe and intelligent inverter to make the photovoltaic power station more efficient. I hope that through the introduction of this article, you will have a further understanding of the inverter.


Post time: Jun-23-2022

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