Solar power generation, as a new type of power generation technology, is widely developed and applied by countries around the world. Solar power generation mainly uses solar modules to convert solar energy into electricity, but at this time, the conversion only generates direct current, which is not stable enough to be directly utilized. Therefore, an inverter is needed to convert direct current into current electricity, which is more stable and convenient for transmission and utilization.
1. Introduction to inverters
An inverter is a type of current converter, also known as an inverter power supply, which can convert direct current of or into alternating current, and can be directly used by electrical appliances. Convenient for the use of AC power in some areas without electricity. In fields such as solar and wind energy, inverters are even more indispensable
1.1 Composition and structure
1.1.1 Input interface part
The input interface generally has three indicator signals: working control voltage, DC input voltage, and current control indicator signal.
1.1.2 Voltage starting circuit
When the working control voltage is high, outputting high voltage will cause the backlight tube of the panel to automatically light up.
1.1.3 PWM controller
It consists of internal reference voltage, error amplifier, overvoltage protection, undervoltage protection, short circuit protection, oscillator, PWM, and output transistor.
1.1.4 DC conversion
The core of the inverter, which is the voltage conversion circuit, is mainly composed of MOS switches and energy storage inductors.
1.1.5 LC oscillation and output circuit.
Mainly responsible for boosting and reducing pressure. Before starting the lamp, increase the voltage to 1500v, and after starting, decrease it to 800v.
1.1.6 Output voltage feedback
It plays a good role in stabilizing the output voltage of the circuit.
1.2 Working principle
The inverter converts the input DC voltage into an AC voltage that can be directly used through the above inverter circuit and other structures for current conversion. In general, the current and voltage of the input are low, and a step-up transformer and step-up circuit are needed to increase the voltage to the standard voltage.
1.3 Main functions
The biggest and most significant function of the inverter is current conversion, which can convert direct current into alternating current, providing the possibility for the effective utilization of new energy generation. The solar inverter also has some other functions, such as active operation and shutdown function, maximum power tracking control function, anti independent operation function, active voltage adjustment function, and so on.
2. Application of inverters in solar power generation
2.1 Differences between solar inverters and ordinary inverters
Solar inverters are upgraded inverters specifically developed for solar power generation technology. They can not only convert direct current into usable alternating current, but also perform their unique functions as solar power inverters, such as automatic operation or standby with the rise and fall of the sun. This is also considering that many power stations cannot arrange a large amount of manpower to operate these generators, The humanized design made.
The biggest difference between solar inverters and ordinary inverters is that they have maximum power tracking technology and low voltage ride through function to protect the safe operation of the power grid. Solar inverters can track the maximum input power at different time periods and weather conditions, and use their own voltage control to output electrical energy at the maximum input power, maximizing the efficiency of solar energy utilization.
Compared with ordinary inverters, solar inverters also have the function of automatic control operation and standby. When the solar energy reaches a certain value, the solar inverter will automatically start up and run. However, when the solar energy decreases to a certain value, in order to effectively utilize the solar energy, the current value that causes the solar inverter to stop running will automatically standby and stop running nearby.
2.2 Industry Development of Solar Inverters
With the global development of solar energy, the competition in the solar inverter industry is also intensifying. In order to better adapt to industry changes and development, there have been many mergers and acquisitions of solar inverter enterprises in China. Increase technology investment in products and keep up with the pace of technological development. Due to the close correlation between industry technology level and the development of power electronic devices, circuit topology, dedicated processor chip technology, magnetic material technology, and control theory technology, it seems that the development of solar inverters is actually the common development of the entire industry system.
3. Optimize the structure and performance of solar inverters
3.1 Upgrade design of solar inverters
With the market demand, there are more and more designs for solar inverters.
The single-phase product of the series solar inverter mainly combines the boost circuit with the single-phase transformer free topology structure:
The series solar inverter three-phase product mainly combines a boost circuit with a three-phase three-level transformer free topology.
Power station solar inverters are mainly based on three-phase bridge circuit topology and can be divided into two types: transformer free and transformer equipped.
3.2 Structure and Function Optimization of Solar Inverters
The most important thing to improve in solar power generation systems is conversion efficiency, as high-efficiency inverters can output more electricity within their effective lifespan.
In order to solve the problem of solar power generation efficiency being affected by the fact that the sun is not shining 24 hours a day, the solar power supply system needs to be optimized to include batteries and complex electronic devices required for efficient charging of batteries. When the battery is integrated into the system, additional DC/DC conversion circuits are required for battery charging, as well as battery management and monitoring.
Many solar powered systems are also connected to the power grid, requiring phase synchronization and power factor correction. There are also many usage environments that require complex control. For example, inverters must have a built-in fault warning mechanism to prevent incidents such as power outages in the public power grid.
In order to improve the performance of the entire system, the designer has set up and equipped a micro inverter for each solar module in the system. The advantage of a micro inverter topology is that even if one of the inverters fails, energy conversion can still occur. Other advantages of using micro inverters include the ability to adjust the conversion parameters of each solar panel with high resolution. Each solar panel equipped with a micro inverter can achieve different maximum power tracking based on its own solar environment. This optimizes the entire photovoltaic power generation system and improves the utilization rate of solar energy and the efficiency of solar power generation.
4. Conclusion
Solar inverters are at the core of solar power generation technology and are essential key structures for converting solar energy into AC power. With the development of solar power generation, the market demand for photovoltaic inverters is also increasing. In order to seek long-term development mechanisms, solar inverter companies are continuously increasing investment in product research and development, paying more attention to customer needs and market research. Domestic enterprises are also paying more attention to controlling production costs. With the development and progress of technology, solar inverters will develop towards miniaturization, efficiency, and intelligence, and their popularity and adaptability will also be greatly improved.