What is a high-frequency transformer?

High frequency transformer is a power supply transformer with operating frequency exceeding medium frequency (10kHz), mainly used for high frequency switching power supply, but also for high frequency inverter power transformer and high frequency inverter power supply. According to the working frequency, it can be divided into several levels: 10kHz-50kHz, 50kHz-100kHz, 100kHz~500kHz, 500kHz~1MHz, and above 10MHz.

How to reduce the leakage inductance?

1. Reduce the number of turns of the primary winding; 2. Increase the width of the winding (for example, select the EE type core to increase the skeleton width b); 3. Increasing the height and width ratio of the winding is to reduce the thickness of the winding and increase the height of the winding; 4. Increase the degree of coupling between the windings. 5. Reduce the number of turns of the winding, and choose magnetic materials with high saturation magnetic induction strength and low loss; 6. Reduce the insulation thickness between the windings as much as possible. 7. Step-down transformer, secondary winding sandwiched in the middle of the primary winding; booster transformer, primary winding sandwiched in the middle of the secondary winding. 8. Double winding or multi-line main winding 9. interlayer winding method is obvious to improve the sense of leakage 10. Reduce the air gap (if it cannot be reduced, you can use larger magnetic core), which is more obvious to improve the leakage sense 11. The secondary corresponds to the middle of the primary, at least do not deviate, to improve the sense of leakage is also more obvious 12. Reduce the primary and secondry turn ratio, have some impact on improving the leakage 13. If the secondary winding layer is not full, it can be evenly wrapped over a layer, which has a little impact on improving the leakage

How to deal with the motor and circuit breaker of the front end in the system?

When there is a strong interference from the motor and circuit breaker at the front end of the module, the interference equivalent model is the rapid transient pulse group interference in EMC, which will cause crash to customer system processor. It is recommended that EMC filter to be added at the front end of the module.

Why does the product work on empty or light load with howling phenomenon?

In order to improve the efficiency and standby power consumption under low power conditions, AC-DC products work in the cycle jump mode under light load conditions. At this time, the product is in the frequency conversion mode (the normal working cycle is 65KHZ or 100KHZ), the output voltage changes greatly, and the ripple is relatively high, but the output voltage is stable.It is normal to have a large ripple at a light load (less than 10%). To avoid this situation, it is recommended that the customer use the load of not less than 10%.

Why is the input voltage indicated on the specification ranging from 90 to 305 V A C and the 100-277 V A C shown on the LED power supply product label?

In the safety regulation approval process, the review agency will use stricter test methods to test the product. When testing the input voltage, they set a tolerance ± 10% of the input voltage on the product label. So it is also normal to work at the voltage described in the specification. As for the voltage marked on the label, one purpose is to meet the requirements of the safety regulation, on the other hand is to enable the customer to properly access the appropriate working voltage.

What is the difference between isolated and non-isolated drives?

Non-isolation refers to the direct electrical connection between the output terminals and the input terminals.The lack of transformer isolation in non-isolated circuit means that the LED is more vulnerable to surges from AC power sources due to load switching transients or primary side interference. Isolated drivers: 1. Flyback converter topology 2. more expensive 3. High efficiency 88%. Non-isolated drives: 1. Buck or step-down-boost topology 2. More efficient 3. Insulation leads to less heat dissipation.