Auxiliary power supplies are often small compared with the main power stage, but their transformer design has a direct effect on system reliability. They power controllers, drivers, relays, sensors, communication circuits, fans, and protection logic. If the auxiliary transformer fails or runs unstable, the entire equipment can stop working.
BaoHui Tech manufactures high frequency transformers, power transformers, inductors, filters, and custom magnetic components for industrial equipment, inverters, UPS systems, chargers, and power supplies. Auxiliary transformer design should be based on the real load profile and safety requirements, not only nominal output voltage.
Define all auxiliary loads
Auxiliary supplies may feed multiple circuits with different current behavior. A controller may draw steady current, while a relay or fan may create short peaks. Gate drivers, communication modules, displays, and protection circuits may have their own startup requirements. The transformer specification should include rated load, peak load, standby load, and duty cycle.
Startup and low-load behavior
Some auxiliary supplies must start reliably across a wide input voltage range and remain stable at very light load. Transformer magnetizing inductance, leakage inductance, turns ratio, and auxiliary winding behavior can influence startup and regulation. These details should be checked in the actual circuit.
Isolation and safety spacing
Auxiliary transformers may cross isolation boundaries between mains, high-voltage DC bus, control circuits, and user-accessible interfaces. Creepage, clearance, hipot voltage, insulation class, and winding separation should match the system requirement. Adding insulation after sample approval can change leakage and size.
Thermal rise in control cabinets
Industrial equipment often runs in warm cabinets with limited airflow. A small auxiliary transformer can still overheat if it is close to power modules or operates continuously. Temperature rise testing should reflect the final enclosure and load pattern.
EMI and noise coupling
Auxiliary supplies can inject switching noise into sensitive control electronics. Transformer capacitance, shielding, winding order, and grounding strategy may affect the noise path. Common mode filters and layout should be coordinated with the transformer design.
FAQ
What is an auxiliary power supply transformer?
It is a transformer used to power control, driver, sensing, communication, and protection circuits inside a larger power system.
Can BaoHui Tech make custom auxiliary transformers?
Yes. BaoHui Tech supports custom auxiliary power supply transformer manufacturing based on voltage, load, isolation, size, thermal, and production requirements.
A good auxiliary transformer is specified from the complete control-power requirement. That includes startup, load variation, insulation, thermal behavior, and repeatable production testing.