12v electronic transformer circuit diagram (electronic transformer principle and function)

2019-05-08 14:34:51 JUKE CHINA ODM OEM Transformer factory Read

12v electronic transformer circuit diagram (electronic transformer principle and function)

First, an introduction to Electrical Transformers

Electronic Electric Transformer (PET), also known as Electronic Power Transformer (EPT), Solid State Transformer (SST) and Flexible Transformer (FT), is a new type of transformer that realizes energy transfer and power conversion through power electronics technology. . By analyzing and summarizing the existing power electronic transformer topology, the power electronic transformer can be defined as follows: the so-called power electronic transformer is a combination of power electronic conversion technology and high-frequency power conversion technology based on electromagnetic induction principle. A stationary power device that implements the conversion of one electrical characteristic electrical energy into another electrical characteristic electrical energy. The power characteristics of electric energy mentioned here mainly refer to the magnitude, frequency, phase, phase number, phase sequence and waveform of voltage (or current).
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Second, Electrical Transformers classification

A is classified by working frequency:

Power frequency transformer: working frequency is 50Hz or 60Hz

IF transformer: operating frequency is 400Hz or 1KHz

Audio transformer: operating frequency is 20Hz or 20KHz

Super audio transformer: above 20KHz, no more than 100KHz

High-frequency transformer: The operating frequency is usually above KHz to over 100 KHz.

B is classified by purpose:

Power transformer: A transformer used to supply the power required by electronic equipment

Audio Transformer: Transformer for audio amplifier circuits and audio equipment

Pulse transformer: a transformer that operates in a pulse circuit. Its waveform is generally a unipolar rectangular pulse wave.

Special transformer: Transformer with special function, such as parametric transformer, voltage regulator transformer, super isolation transformer, transmission line transformer, leakage transformer

Switching power supply transformer: transformer used in switching power supply circuit

Communication transformer: used for transformers in the communication network that are isolated and filtered
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Third, the characteristics of electronic transformers

1 small in size and light in weight;

2 It can be cooled by air, no insulation oil is needed for isolation, pollution is reduced, maintenance is convenient, and safety is good;

3 enables the secondary side of the transformer to output a constant amplitude voltage;

4 can improve the power quality, can obtain the input current and output voltage of the sinusoidal waveform and can realize the unit power factor, and the voltage and current on both sides of the transformer can be controlled, so the power factor can be adjusted arbitrarily;

5 With the function of the circuit breaker, the high-power power electronic device can turn off the faulty large current instantaneously (in the subtle time), eliminating the relay protection device.
electronic transformer.jpg

Fourth, the principle of electronic transformer

Power electronic transformer is a power transmission and distribution device that combines power electronic converters (rectifiers, inverters) and high-frequency transformers to realize the basic functions of electric power conversion, energy transmission and system isolation of traditional power transformers. Since power devices currently applied to power systems are lower in terms of capacity and withstand voltage than transmission systems, it is expected that power electronic transformers should be implemented in the power distribution field in the future.

The power electronic converter (rectifier, inverter) of the power electronic transformer should consist of two parts: the main circuit and the control circuit. For the transformer of the power distribution system, in order to be consistent with the conventional power transformer, the power electronic converter connected to the power supply side and the corresponding winding of the corresponding high frequency transformer are defined as the primary side; the power electronic converter connected to the load side And the corresponding winding of the corresponding high frequency transformer is defined as the secondary side. The two are connected by a high frequency transformer.

The working principle is: on the primary side, the high frequency of the power frequency busbar becomes a high frequency alternating square wave through the action of the power electronic converter, that is, the frequency of the voltage is increased on the primary side to achieve the effect of frequency up. Since the volume of the transformer is related to the saturation magnetic flux density of the core material and the maximum allowable temperature rise of the winding, the transformer having a large saturation magnetic flux density is also large. The saturation flux density of the core material is inversely proportional to the operating frequency of the transformer. Therefore, the up-regulation of the primary-side power electronic converter can improve the utilization of the core material, thereby reducing the volume of the transformer and saving the transformer. space. This is also a major advantage of power electronic transformers compared to conventional power transformers.
electronic transformers.jpg

Five, the role of electronic transformers

In the electronic circuit, it plays the role of boosting, stepping down, isolation, rectification, frequency conversion, phase reversal, impedance matching, inverter, energy storage and filtering.
Six, 12v electronic transformer circuit diagram

The working principle of the electronic transformer is similar to that of the switching power supply. The VD1~VD4 converts the commercial power into DC, and then converts the DC into a high-frequency current of several tens of kilohertz, and then uses a ferrite transformer to step down the high-frequency and high-voltage pulses. as the picture shows). In the figure, R2, C1, and VD5 are startup trigger circuits. C2, C3, L1, L2, L3, VT1, and VT2 constitute a high frequency oscillation portion.
electronic transformer.jpgVD1~VD4 are 1N4007 rectifier diodes, and VD5 is a 32V trigger diode. L1, L2, and L3 are wound around a magnetic ring of H7 × 4 × 2 cubic meters, respectively, and the phases are as shown in the figure. L4 and L5 are wound around a magnetic ring of H31×18×7 cubic meters, and VT1 and VT2 are made of high-power silicon tubes with a withstand voltage of BVceo≥350V. There are no special requirements for other components.

When the electronic transformer is working normally, the working voltage at point A is about 215V, the point B is about 108V, the point C is about 10V, and the point D is 25V. If it does not oscillate, check if the phase of VT1, VT2 and L1, L2, L3 is normal. Changing the number of turns of L5 changes the output high frequency voltage.

Component serial number parameters: R1/1Ω/1WR2/200K, C1=0.01/100V, C2C3/0.47/250V, C4C5/1000P/1KV. VT1VT2/C3039L1L2/6T, L3/1T