A switching device used in the industrial field, the working principle and classification of high-frequency inverters

What is a high-frequency inverter? What is its working principle and classification basis? High-frequency inverter is a switching device used in the industrial field. What is the working principle of a high-frequency inverter? This equipment uses Controlled by program logic. High frequency inverter can be used in the telecommunications industry and is a switching device in computer rooms. This kind of power supply can be used in the solar energy industry and power generation industry. It is a switching power supply device that uses data line output and is very safe. This article mainly introduces the working principle of high-frequency inverter and the difference between high-frequency inverter and low-frequency inverter. Follow the editor to learn more.

How does a high frequency inverter work?

A high-frequency inverter is a DC to AC transformer. It is actually a voltage inversion process with a converter. The working principle of the high-frequency inverter is that the converter converts the AC voltage of the power 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 power; both parts are equally The widely used pulse width modulation (PWM) technology is adopted. Its core part is a PWM integrated controller, the Adapter uses UC3842, and the inverter uses TL5001 chip. The operating voltage range of TL5001 is 3.6~40V. It is equipped with an error amplifier, a regulator, an oscillator, a PWM generator with dead zone control, a low-voltage protection circuit and a short-circuit protection circuit.

1. Input connection part: The input part has 3 signals, 12V DC input VIN, working enable voltage ENB and Panel current control signal DIM. VIN is provided by the Adapter, and the ENB voltage is provided by the MCU on the motherboard. Its value is 0 or 3V. When ENB=0, the inverter does not work, and when ENB=3V, the inverter is in normal working condition and the DIM voltage is Provided by the mainboard, its variation range is between 0~5V. Different DIM values ​​are fed back to the feedback terminal of the PWM controller. The current provided by the inverter to the load will also be different. The smaller the DIM value, the smaller the current output by the inverter. The bigger.

2. Voltage starting circuit: When ENB is at high level, it outputs high voltage to light up the Panel's backlight tube.

3. PWM controller: It has the following functional components: internal reference voltage, error amplifier, oscillator and PWM, overvoltage protection, undervoltage protection, short circuit protection, and output transistor.

4. DC conversion: A voltage conversion circuit is composed of a MOS switching tube and an energy storage inductor. The input pulse is amplified by a push-pull amplifier and drives the MOS tube to perform switching actions, so that the DC voltage charges and discharges the inductor, so that the other end of the inductor can Get AC voltage.

5. LC oscillation and output circuit: ensure the 1600V voltage required to start the lamp, and reduce the voltage to 800V after the lamp is started.

6. Output voltage feedback: When the load is working, the sampling voltage is fed back to stabilize the inverter voltage output.

Classification of high frequency inverters

1. Square wave inverter

The AC voltage waveform output by the square wave inverter is a square wave. The inverter circuits used by this type of inverter are not exactly the same, but the common feature is that the circuit is relatively simple and the number of power switch tubes used is small. The design power is generally between one hundred watts and one kilowatt. The advantages of square wave inverter are: simple circuit, cheap price and easy maintenance. The disadvantage is that the square wave voltage contains a large number of high-order harmonics, which will produce additional losses in load appliances with iron core inductors or transformers, causing interference to radios and some communication equipment. In addition, this type of inverter has shortcomings such as insufficient voltage regulation range, incomplete protection function, and relatively high noise.

2. Step wave inverter

The AC voltage waveform output by this type of inverter is a step wave. There are many different lines for the inverter to realize step wave output, and the number of steps in the output waveform varies greatly. The advantage of the step wave inverter is that the output waveform is significantly improved compared to the square wave, and the high-order harmonic content is reduced. When the steps reach more than 17, the output waveform can achieve a quasi-sinusoidal wave. When using transformerless output, the overall efficiency is very high. The disadvantage is that the ladder wave superposition circuit uses a lot of power switch tubes, and some of the circuit forms require multiple sets of DC power inputs. This brings trouble to the grouping and wiring of solar cell arrays and the balanced charging of batteries. In addition, the staircase wave voltage still has some high-frequency interference to radios and some communication equipment.

High frequency inverter features

1. Wide input voltage range, high voltage stabilization accuracy, and strong environmental adaptability;

2. Adopt special microprocessor control and digital technology, leading the world;

3. Pure sine wave output, excellent electrical performance indicators;

4. LED+LCD display, human-machine interface is friendly, intuitive and convenient, and can display the inverter working status, load status, environmental status and parameters at any time;

5. Choose bypass priority or inverter priority at will;

6. Input and output are electrically isolated and can withstand the impact of computer load startup surge;

7. High-efficiency inverter, low no-load loss;

8. Advanced manufacturing technology and elegant and beautiful products;

9. It has input over-voltage, under-voltage and reverse connection protection; output over-load and short-circuit protection; mains bypass high and low voltage protection and a series of protections;

10. In the absence of DC, it can be started by AC;

11. Fully automated maintenance, suitable for unattended stations.

The difference between high frequency inverter and low frequency inverter

1. According to the spectrum division table formulated by the Institute of Electrical and Electronics Engineers (IEEE), the low frequency frequency is 30~300kHz, the medium frequency frequency is 300~3000kHz, the high frequency frequency is 3~30MHz, and the frequency range of 30~300MHz is very high frequency. , 300~1000MHz is ultra-high frequency. Compared with low-frequency signals, high-frequency signals change very quickly and have sudden changes; low-frequency signals change slowly and have smooth waveforms.

2. Power supply and signal are different. The voltage provided by the power board generally has a frequency of 0 (DC power supply) or 50Hz (AC power supply). The signal can be said to be high frequency or low frequency (or other frequencies). It is difficult to say whether the power board is used for power supply, because it is only used for power supply and the frequency is very low. If it must be said, it is only low frequency.

3. The main advantages of high-frequency inverters are light weight, small size, low standby power, and relatively high efficiency (relatively saving some power). The disadvantage is that the impact resistance is not as good as the power frequency inverter (that is, the low frequency you mentioned), and it may not be able to carry electrical appliances such as food mixers and hand drills. The disadvantages of low frequency are that it is heavier and larger, the price may be slightly more expensive, and its own loss will be slightly greater (it consumes a bit of electricity). The advantage is that it is relatively sturdy and has better ability to carry impact electrical appliances. The above is the analysis of high-frequency inverter appliances. I hope it can help you.