How do we identify the quality of switching DC power transformers?
Switching DC power transformer is a DC power transformer with switching tubes. When designing DC power supply circuits, in addition to the DC voltage conversion function of ordinary transformers, they also have insulation and power transfer functions, which are often used in switch DC power supplies and high-frequency DC power supply equipment.
The DC power transformer, switch DC transformer, and switch tube together form a self-excited (or other) intermittent oscillator, which modulates the input DC voltage into high-frequency pulse DC voltage. In the construction of flyback DC circuits, transformers convert electrical energy into magnetic field energy, store it when the switching tube is turned on, and release it when the switching tube is turned off. In the design of a forward DC power supply circuit, when the switching transistor is turned on, the input DC power supply voltage is directly supplied to the load, and energy is stored in the energy storage inductor.
When the switch tube is turned off, the energy storage inductor will continue to transmit current to the load. The input DC-DC power supply voltage is converted into various required low voltages.
The basic configuration of a DC switching transformer is the main material of the DC switching transformer, with magnetic materials, wire materials, and insulation materials being the core of the switching transformer.
Magnetic material: The magnetic material used in switch transformers is soft ferrite, which can be divided into two categories based on its composition and applicable frequency: MnZn and NiZn. The former has high magnetic permeability and high saturation magnetic induction intensity at low to medium levels, and has a loss effect in the low-frequency range. Magnetic cores come in various shapes, such as EI type, E type, EC type, and other wires. Enamel wire: commonly used for winding small electronic transformers. Enamel wire includes high-strength polyester enamel wire (QZ) and polyurethane enamel wire (QA).
According to the thickness of the coating, it can be divided into type 1 (thin coating type) and type 2 (thick coating type). The former insulation coating is a heat-resistant polyurethane coating that reaches 60kV/mm, while the latter insulation layer is a polyurethane coating with strong self-adhesive and self soldering properties (380 ° C). Pressure sensitive tape can be directly welded without peeling off the paint film, and insulating tape has high electrical strength.
The classification and parameters of switch DC power transformers are divided into single excitation switch DC power transformers and double excitation switch DC power transformers. The functional principles and structures of two switch DC transformers are different. The input DC power supply voltage of a DC transformer is a unipolar pulse, which is divided into forward and reverse DC power supply voltage outputs. On the other hand, the DC input voltage of a DC transformer with two excitation switches is a bipolar pulse, usually bipolar. Pulse DC power supply output voltage.
