Principle of sine wave inverter

Sine wave inverters are widely used in various types: microcomputer systems, communication systems, household, aviation, emergency, communications, industrial equipment, satellite communication equipment, military vehicles, medical ambulances, police cars, ships, solar and wind power generation needs The place of emergency backup power supply can constitute EpS emergency power supply system.

Before introducing the working principle of the sine wave inverter, let's first introduce the working principle of the inverter.

The inverter is a DCtoAC transformer, and it is actually a voltage inversion process with the converter. The converter converts the AC voltage of the grid into a stable 12V DC output, while the inverter converts the 12V DC voltage output by the Adapter into high-frequency high-voltage AC; both parts also use a more used pulse width Modulation (pWM) technology. Its core part is a pWM integrated controller, Adapter uses UC3842, and inverter uses TL5001 chip. The operating voltage range of TL5001 is 3.6～40V, and there is an error amplifier, a regulator, oscillator, pWM generator with dead zone control, low voltage protection circuit and short circuit protection circuit inside.
The difference between a sine wave inverter and an ordinary inverter is that the output waveform is a complete sine wave with low distortion, so it has no interference to radios and communication equipment, low noise, complete protection functions, and high efficiency of the whole machine. The reason why the sine wave inverter can output a complete sine wave is because it uses SpWM technology, which is more advanced than pWM technology.

The principle of SpWM is based on the equivalent principle of pulse acting on a time function device: if a pulse acts on a time function device, the product of the peak value and the acting time is equal, and these pulses can be approximated as equivalent.

SpWM is based on comparing a triangular wave with a fixed frequency and a fixed peak value (such as a switching frequency of 10k) with a reference sine wave (fundamental wave) of variable frequency and voltage transformation, thereby pulsing the DC voltage (pulse with varying duty cycle) to approximate the action of the reference sine wave On the device. Adjust the amplitude and frequency of the reference sine wave to generate a DC voltage pulse width modulation wave with different amplitude and frequency equivalent to the reference sine wave.

Advantages of sine wave inverter

Its advantages are that the output waveform is good, the distortion is very low, and its output waveform is basically the same as the AC waveform of the mains grid. In fact, the AC power provided by a good sine wave inverter is higher than the quality of the grid. The sine wave inverter has little interference to radios, communication equipment and precision equipment, low noise, strong load adaptability, can meet all AC load applications, and the overall efficiency is high;

The output of the sine wave inverter is the same or better sine wave AC power as the grid we use daily, and there is no electromagnetic pollution in the grid. Simply put, it has a wide range of applications, strong load capacity, and excellent stability. It can provide the same AC power as normal households. In the case of meeting power, it can drive almost any kind of electrical appliances.


Disadvantages of sine wave inverter

Because of the high manufacturing costs and technical requirements of sine wave inverters, the most pure sine wave inverters are expensive in the market, which has a certain gap with mass consumption and has not been popularized.