ee type transformer noise

EE13 transformers (used by customers on charger boards) are now being supplied in batches and there is a problem of noise inside the transformer during the aging process of 20~30%. What aspects should be adjusted and improved?

Answer 1: Is it true that 20~30% of transformers make noise during the aging process? If there is an abnormal response, it should be high-frequency noise. 1. Soak the existing transformer in Fanli water again to improve the inter-turn insulation of the coil, reduce the inter-turn distributed capacitance of the coil, and reduce leakage inductance. 2. Use a slotted skeleton, because after the coil is slotted, its inter-turn distributed capacitance will be significantly reduced. In this way, the self-resonant frequency of the transformer will be greatly increased, which will help suppress the generation of high-frequency noise.

Answer 2: There are 4 possibilities: 1. The inside of the transformer ages due to temperature rise during the aging process, the insulation characteristics decrease, and spike discharge occurs, which is manifested as noise. 2. The air gap of the transformer core is large and the fixation is not firm. During operation, it buzzes and vibrates slightly during the electromagnetic conversion process, which is manifested as noise. 3. When designing the entire circuit board, the components are not properly matched, causing overvoltage or overcurrent of the chip. Overheating protection causes constant restarts, which manifests as noise. 4. The transformer output shows overclocking on the oscilloscope, and noise also occurs during operation.

Answer three: Describe the conditions under which the problem occurs: Nowadays, there is a problem of noise inside the transformer during the aging process of 20~30% in batch supply. Prerequisite for action: For products that have already been put into batches, it is unacceptable for customers to redesign and modify parameters and specifications. Action: 1. Get the bad sample back, simulate the customer's aging conditions, re-measure the product parameters, check whether the product performance has changed, and determine whether it is a core problem. 2. Check the stability of the insulating oil under aging conditions. If the product is defective, the test parameters are OK. a. Re-immerse the defective product in oil (you can also make the oil thicker), and then ask the customer to confirm. b. Fix the defective magnetic core with BOBBIN glue, and then ask the customer to confirm.