A custom inductor for a pulsed load must be designed around both the individual pulse and the repeating thermal cycle. Peak current sets magnetic stress, while pulse width, rise time, repetition rate, RMS current, core loss, copper loss, and cooling determine temperature and long-term reliability.
Applications include pulsed lasers, radar supplies, solenoid drivers, medical equipment, capacitor chargers, test systems, and energy-storage converters. Two loads with the same peak current can require very different inductors when their pulse duration and repetition rates differ.
Describe the actual waveform
Provide current before the pulse, peak amplitude, rise and fall time, pulse width, repetition rate, burst length, rest interval, and fault case. A rectangular approximation helps early calculations, but measured data reveals overshoot, ringing, and control transitions that can set the true peak.
Check incremental inductance near the peak
Low-signal inductance does not show how the component behaves near saturation. Define a minimum incremental inductance or acceptable inductance drop at the maximum credible current and temperature. A gradual roll-off may be acceptable; a sharp collapse can accelerate current and overload the switch before protection responds.
Separate pulse energy from average heating
A short pulse can store high magnetic energy without causing an immediate large temperature rise. Repetition turns copper and core loss into accumulated heat. Thermal validation should reproduce the burst timing, initial temperature, cooling interval, enclosure, and airflow. Testing one pulse from a cold start is not enough.
Evaluate conductor and core losses
Fast edges and ripple add skin and proximity losses. Gap fringing can heat conductors near a discrete air gap. Core loss depends on flux excursion, waveform, material, and temperature. Litz wire, foil, rectangular wire, and round wire each have useful regions; conductor selection should follow the pulse spectrum and winding geometry.
Mechanical forces and terminals
High peak current produces mechanical force in the winding and terminals. Repeated pulses can loosen conductors, fatigue leads, or create audible noise. Winding restraint, impregnation, core clamping, terminal support, and mounting should be validated together.
Prototype verification checklist
- Initial and incremental inductance across the current range
- Peak current, pulse shape, overshoot, and fault waveform
- Winding resistance and conductor temperature
- Core and gap-region temperature during repeated bursts
- Recovery during the specified rest interval
- Acoustic noise, movement, terminal stress, and insulation
BaoHui Tech can evaluate custom inductor designs from measured waveforms, inductance-versus-current targets, insulation requirements, cooling, size, and production tests.
Frequently asked questions
Is a peak-current rating enough?
No. It needs an inductance-drop criterion, pulse duration, initial temperature, repetition rate, and cooling condition.
Why can an inductor pass one pulse but fail during a burst?
Heat accumulates, permeability changes with temperature, and each pulse may start with less magnetic and thermal margin.
What should production test?
Inductance, winding resistance, dielectric strength, turns or polarity where relevant, dimensions, and workmanship are typical. Pulse behavior may be sampled or qualified by design.