sine-wave inverter
The inverter converts DC power (battery, storage bottle) into AC power (usually 220V, 50Hz sine wave). It consists of an inverter bridge, control logic and filter circuit.
Inverters can be classified according to their output waveform into square wave inverters, modified sine wave inverters, and pure sine wave inverters.
The advantage of a sine wave inverter is that it has a good output waveform with very low distortion, and its output waveform is almost identical to the AC waveform of the utility grid. In fact, a high-quality sine wave inverter provides AC power that is superior to the grid's quality. Additionally, sine wave inverters have minimal interference with radios, communication devices, and precision equipment, produce low noise, have strong load adaptability, can meet the application needs of all AC loads, and have relatively high overall efficiency.
Its disadvantages include more complex circuitry compared to modified sine wave inverters, higher requirements for control chips and maintenance technology, and a relatively high price.
Development Trend
With the rapid advancement of power electronics technology and the increasing demands of various industries for improved inverter control performance, sine wave inverters have also seen swift development. Currently, the main development directions for inverters are:
Increasing the operating frequency of power switching devices not only reduces the overall system size but also effectively suppresses audio noise and enhances the inverter’s output voltage dynamic response capabilities. Power switching devices operating at high frequencies correspond to high-frequency isolation transformers, and the application of high-frequency isolation transformers further reduces the system size.
The root mean square (RMS) value is the primary parameter of the inverter's output voltage. A high-performance inverter maintains a stable RMS value of the output voltage while delivering high waveform quality and strong adaptability to nonlinear loads. Since inverter loads may often change suddenly, a high-performance inverter requires a high transient response capability for the output voltage. Another important parameter for AC output voltage is frequency; a good inverter demands not only a stable RMS value but also a stable frequency. Inverters with these characteristics can truly be considered high-performance inverters.
Current inverter technology can produce high-power products, but if a high-power inverter system fails, it can lead to system paralysis. In a system composed of low-power inverters using parallel technology, the normal operation of each unit does not affect the others, significantly enhancing the system's reliability.
Miniaturization results from high-frequency operation because the main approach to making inverters smaller is to increase the switching frequency and use high-frequency transformers. Another method is to improve control methods and optimize the spectrum of the SPWM wave to reduce the size of the filters.
Many inverter systems use specific circuit topologies to convert DC into high-frequency AC pulses, which are then rectified to obtain the required DC voltage. The current spikes at the output can decrease the input power factor, but improving the input side power factor can effectively mitigate harmonic pollution from the inverter to the power grid.
The digitalization of inverters isn't simply about using digital devices like FPGAs and microcontrollers in inverters; rather, it's the entire system relying on the computing power and discrete control methods of digital devices. As hardware develops and processor speeds increase, inverters are advancing towards intelligentization and digitalization.
Application Fields of Sine Wave Inverters
In a broad sense, new energy refers to solar power, which includes wind energy, water potential energy, chemical energy, etc. Emerging energy sources such as solar and wind power are set to become primary energy sources. These new energies are typically harnessed using photovoltaic cells made from semiconductor materials, and are converted into various forms of electrical energy needed by people through specific scientific and technological methods, with inverter technology being one of the key technologies.
Effective management of harmonic pollution not only improves the operational quality of electrical equipment and conserves energy but also relates to the safety of national electricity usage. By rectifying the grid power and then using modern inversion technology to convert it back to grid standards, harmonic pollution can be purified, protecting electrical equipment and ensuring user safety. The inverter is an important component in small wind power generation systems, responsible for converting DC into AC to supply power to the load.
Inverters are also widely used in various other fields, such as variable speed control of AC motors, regenerative energy feedback from motor braking, uninterruptible power supply (UPS) systems, induction heating, arc welding power supplies, and frequency conversion power supplies.