[Inverter Transformer] Working Principle of Inverter Transformer What are the winding methods of inverter transformer
Structural features of the inverter transformer
1. The coil is wound in a multi-pie style with F-class or C-class paint, arranged tightly and evenly, and does not contain insulation on the outside. layer, has excellent aesthetics and good heat dissipation performance.
2. The seams of the core are welded by sub-arc welding. After the coil and core are assembled into one, they undergo pre-baking → vacuum impregnation → thermal baking and curing. This process makes the coil and core of the transformer firmly Combined together, it not only greatly reduces the noise during operation, but also has an extremely high heat resistance level.
3. The exposed parts are all treated with anti-corrosion treatment, and the lead-out terminals are wire terminals or copper bar terminals.
The working principle of the inverter transformer
The control circuit controls the entire operating system. The inverter circuit completes the conversion of DC power into AC power, and the filter circuit is responsible for it. No need The wave signal is filtered out, and the rough process is like this. To put it in a little more detail, it is probably:
1. The proper circuit converts DC into AC;
2. The coil transformer boosts the voltage to turn some irregular AC into square wave AC.
3. The rectifier circuit converts alternating current into square wave alternating current into sine wave alternating current.
What are the winding methods for inverter transformers
First, each winding should use multiple strands of thin copper wires and wind them together instead of using a single thick copper wire. Copper wire, because high-frequency alternating current has a skin effect. The so-called skin effect simply means that high-frequency alternating current only flows along the surface of the conductor, but no current flows inside the conductor (In fact, the closer to the central axis of the conductor, the weaker the current. The closer to the surface of the wire, the stronger the current). Using multiple strands of thin copper wire and winding them together is actually to increase the surface area of the wire, thereby using the wire more efficiently.
For example, the primary 3T+3T, if you use a single enameled wire with a diameter of 2.50mm, the conductor The cross-sectional area is 4.9 square millimeters, and if an enameled wire with a diameter 0.41mm is used(Single root cross-sectional area0.132square millimeters)38The roots are wound together, and the total cross-sectional area also meets the requirements.However, the surface area of the wire in the second method is much larger(The surface area of the wire in the first method is: the cross-sectional circumference of the single-strand wire × the number of strands × the total length of the winding=2.5× 3.14×1×L=7.85L, the second method of wire The surface area is: Cross-sectional circumference of single-strand wire×number of strands×total winding length=0.41×3.14 span>×38×L=48.92L, the latter is the former 48.92L/7.85L=6.2 times ), the effective utilization rate of the wire is higher, the current is smoother, and because the thin wire is Soft and easier to wind, the secondary 75T high-voltage winding can be wound with 3~5 roots.
The second is to use layered and segmented winding method. The main purpose of this winding method is to reduce high-frequency leakage inductance and distributed capacitance.For example, in the above-mentioned winding method of the transformer, the primary is divided into two layers, and the secondary is divided into three layers and three sections. Specifically:
① Wind the first section of the secondary high-voltage winding and connect the lead wire (Head) span>, first use 5 wires and wind them around the secondary high-voltage winding 25T. Do not cut the wires. Then wrap a layer of insulating paper(The insulating paper should be thin, just wrap it in one layer, otherwise the entire wire package may not be able to accommodate the insulating paper due to the following multiple uses. ), prepare to wind half of the primary low voltage winding.
②Wrap half of the primary low-voltage winding. Reserved lead lines(Header), note that it is reserved, because it must be unified and connected before connecting the lead wires. The word “reserved” is used in the following primary Same reason. Use19roots and wind them in parallel3T, reserve the center tap, and then wind them in parallel3T, reserve the lead wire(tail), cut the wire. There is another trick in the specific operation, that is, due to the large number of strands, 19 It is not convenient to wind the strands together at one time, and the torque and tension are also large, so it can be done multiple times, as here It can be done three times, each time using 6 to 7 strands, so that it can be wound more smoothly. Pay attention to putting the head, middle and tail of the three windings together and in the same winding direction. Then wrap a layer of insulating paper and prepare to wind the second section of the secondary high-voltage winding.
③Wrap the second section of the secondary high-voltage winding. Turn over the uncut secondary high-voltage winding wire up(Be careful not to touch the primary winding wire in front, and use insulating paper to separate it if necessary), and then wrap 25T together. Note that the wrapping direction should be the same as the first section before, and the thread should not be cut. Wrap another layer of insulating paper and prepare to wind the other half of the primary low-voltage winding.
④Wrap the other half of the primary low-voltage winding. Follow the steps again ② Wind the primary low-voltage winding once in the same way. Note that the winding direction should be the same as the previous half. Cut the same wire, wrap it with a layer of insulating paper, and prepare to wind the third section of the secondary high-voltage winding.
⑤ Wind the third section of the secondary high-voltage winding. Follow the instructions in step ③ to finish winding the remaining secondary high-voltage winding 25T, still paying attention to the same winding direction as the previous two sections. Connect the lead wire (Tail) and cut the wire. At this point, all windings have been wound.
⑥ Combine the primary low-voltage winding. Connect the primary low-voltage winding wound twice before in parallel with the head, the center tap with the center tap, and the tail withThe tails are connected in parallel(In this way, the number of winding turns is still3T+3T, and the total parallel connection is38roots) and connect the lead wires to obtain the first, middle and tail terminals of the primary low-voltage winding. Finally, wrap a layer of insulating tape and the wire package is completed.
Precautions for using inverter transformers
1. The DC voltage must be consistent
Each inverter transformer has a DC connection The voltage value, such as 12V, 24V, etc., requires that the selected battery voltage must be consistent with the DC input voltage of the inverter transformer. For example, a 12V battery must be selected for the 12V inverter transformer.
2. The output power of the inverter transformer must be greater than the power used by the electrical appliance. Especially for electrical appliances with high power at startup, such as refrigerators and air conditioners, a larger margin must be left.
3. The positive and negative poles must be connected correctly. The DC voltage connected to the inverter transformer is marked with positive and negative poles. Red is the positive pole (+), black is the negative pole (-). The battery is also marked with positive and negative poles, red is the positive pole (+), black is the negative pole (-). When connecting, you must connect the positive pole (red to red) and the negative pole. Connect negative (black connects black). The diameter of the connecting wire must be thick enough, and the length of the connecting wire must be reduced as much as possible.
4. It should be placed in a ventilated and dry place, be careful of rain, and keep a distance of more than 20cm from surrounding objects. Keep away from flammable and explosive materials. Do not place or cover other items on the machine. The ambient temperature of use is not greater than 40℃.
5. Charging and inversion cannot be performed at the same time. That is, the charging plug cannot be inserted into the electrical circuit of the inverter output during inversion.
6. The interval between two power-ups should be no less than 5 seconds (cut off the input power).
7. Please wipe with a dry cloth or anti-static cloth to keep the machine clean.
8. Before connecting the input and output of the machine, please first ground the shell of the machine correctly.
9. To avoid accidents, users are strictly prohibited from opening the chassis for operation and use.
10. When you suspect that the machine is faulty, please do not continue to operate and use it. You should cut off the input and output in time, and have it inspected and repaired by qualified maintenance personnel or the company’s special maintenance unit.
11. When connecting the battery, please make sure there are no other metal objects on your hands to avoid battery short circuit and burns to the human body.
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