High-frequency transformer winding in switching power supply
High frequency transformer winding in switching power supply
1: Using the dedicated transformer design software PIXlsDesigner and PITRANSFORMERDesigner, will take the required parameters, such as input voltage range, output voltage requirements, bias voltage magnitude, transformer estimated power, power factor, rated load, primary coil layer, secondary coil匝For the input of several parameters, the PI software will give a reasonable transformer parameter according to the parameters input by the user, and then the designer can wind the transformer according to the given parameters. The software will give the following parameters: primary coil, feedback coil The number of layers of the secondary coil, the number of turns, the size of the wire, the direction of winding, the size of the air gap, the number of layers of the tape between the coil and the coil, the type of the skeleton, the type of the magnetic core, the requirements for the immersion paint, and the like.
2: With these parameters, you can wind the transformer. Before winding the transformer, first assign a number to the foot of the skeleton. For example, we need to wind an input voltage of +24V, output 1 is +9V, and output 2 It is a +15V transformer, and the power output of the 2 output terminals is 1.5W. Then the winding method of this transformer is as follows:
The winding method of the primary coil: starting from the lead 2, using the enamelled wire with a wire diameter of 0.19 mm to wrap around the frame for 53 turns, it is estimated that there are two layers, and the winding should be as flat as possible. At the end of pin 1, after winding, wrap two layers with insulating tape.
Winding method of the bias coil: starting from the lead 5, use the enameled wire with a wire diameter of 0.13 mm to wrap around the frame 27 to the end of the pin 4. After winding, wrap two layers with insulating tape and wrap it with a layer of insulating tape. All but the pins have exposed coils.
9V end coil winding method: wrapped in 7-foot and 6-foot bottom with insulating tape, using enameled wire with a diameter of 0.35 mm, starting from 7 feet and ending with 20 to 6 feet, wrapped in two layers with insulating tape. Wrap the windings other than the 7-pin 6-pin with an insulating tape.
15V end coil winding method: wrapped in 10 feet and 9 feet with insulating tape, using enameled wire with a wire diameter of 0.19 mm, starting from 10 feet and ending with 34 turns to 9 feet, wrapped with two layers of insulating tape, and then loaded with two fast magnetic The core is placed with 0.3 mm thick paper (ie, air gap, about 4 layers of white paper thickness) between the two cores. After flattening, the core and the skeleton are wrapped with tape. (Insulation tape refers to 4KV insulation)
The EPC13 skeleton pin diagram is as follows:
3: Test transformer output and load capacity
Test method: Install the wound transformer on the test board that has been successfully tested, and test the output of the circuit and the load capacity. If the output end and the load capacity are normal, the transformer withstand voltage capability can be tested.
4: Test transformer withstand voltage capability.
The transformer withstand voltage test is divided into three groups, namely the primary end (1, 2 feet), the 9V end (6, 7 feet), and the 15V end (9, 10 feet). Add 3KV AC voltage to any two groups for 20 seconds (any clip of each end of the clip can also be fully clipped). If the voltage tester alarms, the transformer will be unqualified and will not pass the alarm.