Inverter (Inverter, reverse transformer) is a DC to AC (DC to AC) transformer. It can convert direct current (DC) output into alternating current (AC) 220V sine wave 50Hz or other types of alternating current, which can be used for various types of electrical equipment to meet the needs of users in mobile power supply places or areas without power to the maximum extent. Widely used in communications, industrial equipment, satellite communication equipment, military vehicles, medical ambulances, police cars, ships, solar and wind power generation fields.
Inverter use

1, inverter is a key component of the commercial power grid or local power grid: with the development of economic society, the human society's demand for energy is growing, the shortage of oil resources and its price is rising, and the use of traditional energy is facing many problems such as environmental pollution, so that people turn to the development of clean energy solar energy and wind energy. The inverter is a key component of the entire solar and wind energy system, converting the variable DC output obtained from the solar and wind energy into a clean sinusoidal 50Hz or 60Hz current to meet the 220 volt AC power we are indispensable in our daily environment. Ideal for supplying power to commercial or local power grids.
2, meet “ Move ” The needs of The Times: With the change of people's lifestyle, the high pace of life, high and fast demand for life is expanding day by day. So now 3C products, more digital products are developing in this direction. So we are in a “ Move ” In the era of mobile office, mobile communication, mobile leisure and entertainment in life. In the mobile state, people not only need the low-voltage direct current supplied by the battery or battery, but also need the 220 volt alternating current that is indispensable in our daily environment, and the inverter can meet our needs.
Inverter working principle
The working principle of the inverter is actually a process of converting low-voltage DC to high-voltage AC. Its DC voltage is divided into two ways, one to supply power to the front IC to generate a KHZ level control signal, all the way to the front power tube.
Below are 3 steps in the process of converting from low DC to high AC and the resulting current voltage
for each step Step 1: The power tube is constantly switched on and off by the control signal so that the high-frequency transformer can generate low-voltage high-frequency alternating current.
Step 2: Output high frequency AC through high frequency transformer and then output a high frequency several hundred V DC to the rear power tube through quick recovery diode full bridge rectification.
Step 3: The rear IC generates a control signal of about 50HZ to control the power tube working output of 220V 50Hz AC.
The following are several important inverters:
Sine wave inverter: The output is the same as the daily use of the grid sine wave AC, to provide high-quality AC, can drive any kind of load, but the technical requirements and costs are high.
Square wave inverter: The output is poor quality square wave AC. It can cause severe instability to the load and inverter itself. The production of simple multivibrators, whose technology belongs to the level of the 1950s will gradually withdraw from the market.
Repair sine wave inverter: belongs to the square wave category, there is a time interval between the output waveform from the positive maximum to the negative maximum, the waveform is composed of broken lines, the continuity is not good, but it can meet most of our electricity needs. With high efficiency, low noise and moderate price, it has become the mainstream product in the market.
  Active inverter: An inverter that allows the current in a current circuit to be connected to the grid on the AC side rather than directly connected to the load Passive inverter: The inverter that makes the current in the current circuit not connected to the power grid on the AC side, but directly connected to the load (that is, inverts the direct current to a certain frequency or an adjustable frequency of alternating current supply load).
Inverter key parameters Introduction
Whether it is consumer use or developer design, the following important parameters of the inverter need to be familiar with
1, inverter efficiency:
Inverter efficiency is an important parameter to measure the performance of the inverter, and the inverter efficiency value is used to express the size of its own loss power. It is usually expressed as %. The inverter efficiency is directly related to the system efficiency. If the inverter efficiency is too low, the system efficiency will be seriously reduced.
In the solar photovoltaic power generation system, the conversion efficiency of the solar cell array is generally not more than 18%, and the cost of solar photovoltaic panels is high. If you want to improve the conversion efficiency of 2% to 3% is very difficult, but it is entirely possible to improve the inverter efficiency of 3% to 5%.
The efficiency of the inverter is an important standard for the performance of the inverter, which has an important impact on the photovoltaic power generation system to improve the power generation and reduce the cost of power generation.
2, rated (continuous) output capacity
The rated output capacity is most used to express the ability of the inverter to supply power to the load. The higher the rated output, the stronger the load capacity of the inverter. The output capacity rating is only a reference for purely resistive loads. If the load carried by the inverter is not pure electrical load, the load capacity of the inverter will be less than the given rated output capacity value.
3, output voltage stability
Output voltage stability refers to the stability of the output voltage of the inverter. The inverter generally gives the input DC voltage in the allowed fluctuation range of the inverter output voltage deviation (usually called the voltage adjustment rate) High-performance inverters generally also give the voltage deviation of the inverter output voltage when the load changes from 0% to 100% (usually called the load adjustment rate). The nominal voltage usually refers to the open output voltage, that is, the voltage value without any load and no current output. The terminal voltage of the battery fluctuates greatly during charging and discharging, and the voltage fluctuation of the lead-acid battery can reach about 30% of the normal voltage. Therefore, the inverter must have a good output voltage stability to ensure that the system works in a larger DC input range.
4, reliability
The reliability of inverter is one of the main reasons for the reliability of vibration system. Its reliability requires that the inverter has a good protection function. It includes over current protection and short circuit protection in inverter. Due to load failure, human error and external interference, the power supply system current is too large or short circuit is very likely to occur. To improve reliability, the inverter must be required to have related protection functions.
5, starting performance
Starting performance refers to the ability of the inverter to start with load and the performance of dynamic work. The inverter should be able to ensure its normal start-up under the rated load. Generally, the inverter has better startup performance when the resistive load is working. However, if it is inductive load, such as motors, refrigerators, air conditioners or high-power pumps, the power may be several times more than the rated power when starting. Usually when the inductive load is started, the inverter will withstand a large surge power. Therefore, the startup performance of the inverter requires that the internal components of the inverter can withstand multiple full load starts without causing damage to the power components when the inductive or other load starts.
6, harmonic distortion
When the output voltage waveform of the inverter is sine wave or modified wave, in addition to the fundamental wave, it also contains harmonic components, and the proportion of harmonic components in the total output voltage waveform is usually called harmonic distortion degree. High order harmonic current will generate eddy currents in the electrical load, resulting in serious heating of components, and serious damage to electrical equipment. General inverter will indicate its harmonic distortion degree. The harmonic distortion of square wave inverters is about 40%, which is generally only suitable for pure resistive loads. The harmonic distortion of the modified wave inverter is less than 20%, which is suitable for most loads. The harmonic distortion of sine wave inverter is small, which can be applied to all AC power loads.
Inverter future development direction
The increasingly electrified society now requires more and more inverters in various products, and the demand is also increasing. So at the same time as the rapid development of the inverter, what is its development trend?
1, high-frequency: the improvement of the inverter switching frequency can effectively reduce the volume and weight of the device, while also eliminating the audio noise of the transformer and inductor. The volume and mass of the device are also reduced while the dynamic response of the output voltage is improved.
2, high performance: it requires good voltage regulation performance, no-load and load output voltage RMS should be stable, and the quality of the waveform is also required to be high. The instantaneous response to the output voltage when the load is suddenly added or suddenly reduced is better.
3, parallel and modular: Now the inverter has been developing towards high power and reliability, so in order to improve the reliability of the system, it is necessary to achieve modularity.
4, miniaturization: Miniaturization here refers to the miniaturization of transformers.
5, high input power factorization
6, digital
7, intelligent: No matter what product development to the intelligent state, compared with the traditional model that is definitely a higher level.
Ideal design for inverters
The ideal inverter from DC to AC power is always a certain value without pulsation, DC power waveform and current waveform should not produce pulsation, and in the actual inverter circuit because the number of inverter pulsation is limited, so the inverter power p is pulsating. When the pulsating waveform of the inverter power p is reflected by the DC current, it is called the voltage inverter. Voltage inverter characteristics are :
1, the DC side has a large DC filter capacitance;
2, when the power changes due to the load, the waveform of the AC output voltage is unchanged, that is, the AC output voltage waveform is independent of the load. The waveform of the AC output voltage is formed into square waves by the voltage clamp on the DC capacitor through the action of the inverter switch.
3, there is a feedback diode in parallel with the inverter switch in the inverter, so the AC voltage has nothing to do with the load.
4, the phase of the output current changes with the load power factor, and the commutation is carried out between the same bridge arm switch.
5, the output voltage can be controlled by controlling the amplitude and waveform of the output voltage.