Strong Electromagnetic Pulse (EMP) refers to an instantaneous electromagnetic radiation characterized by an ultra-short rise time, extremely high peak field strength and an ultra-wide frequency spectrum. It mainly includes Nuclear Electromagnetic Pulse (NEMP), Lightning Electromagnetic Pulse (LEMP), High-Power Microwave (HPM), Electrostatic Discharge (ESD), and switching overvoltage pulses from power systems. Its peak electric field can reach tens of thousands of volts per meter with a rise time down to nanoseconds, covering frequencies from kHz to tens of GHz. Coupling into electronic equipment via radiation and conduction, EMP induces extreme transient overvoltage and overcurrent, causing component breakdown, burnout, circuit runaway, functional failure and permanent damage. As core power units in power electronic systems, industrial facilities, defense equipment, communication systems, rail transit and energy infrastructure, high‑voltage power supplies directly connect to power grids, long cables and high‑power loads, making them primary coupling entry points and vulnerable targets for EMP. Their anti‑EMP capability and hardening level determine the survivability, operational stability and functional safety of the entire electronic system under severe electromagnetic environments. EMP imposes extreme technical challenges far beyond conventional EMC requirements: 1. Full‑spectrum comprehensive protection. EMP types differ drastically: NEMP features 1–10 ns rise time, hundreds of nanosecond pulse width and peak field strength up to 50 kV/m; LEMP has 0.1–1 μs rise time, tens of microsecond width and peak current up to hundreds of kA; HPM covers 1–100 GHz with peak field strength up to hundreds of kV/m. Traditional EMI filters only cover low frequencies and fail against full‑spectrum EMP. Power supplies must provide integrated protection across kHz to tens of GHz against NEMP, LEMP and HPM simultaneously. 2. Balance between nanosecond response and high surge capacity. EMP rise times reach nanoseconds, requiring protection devices with response ≤1 ns to suppress transient overvoltage instantly. Meanwhile, peak surge currents can reach tens to hundreds of kA, demanding massive current handling and energy absorption. Conventional components cannot combine ultra‑fast response with ultra‑high surge capability. 3. Reliable protection under high‑voltage high‑power operation. High‑voltage supplies operate at hundreds to thousands of volts. Protection circuits must remain stable without false triggering or aging under rated high voltage, while clamping overvoltage instantly and absorbing pulse energy without breakdown during EMP impact. Precise clamping voltage, low residual voltage and long service life are mandatory. 4. Suppression of multi‑path coupling. EMP penetrates via radiation, power conduction, signal conduction and grounding coupling, disturbing control, driver and sampling circuits and causing logic chaos, signal distortion and accidental triggering. Full blocking of all coupling paths is required to protect sensitive internal circuits. 5. Compatibility between protection circuits and power system architecture. Additional protection changes system impedance, potentially causing resonance, waveform distortion and efficiency loss, especially in high‑frequency high‑voltage converters. Parasitic parameters must be precisely matched with topology, impedance and operating frequency to maintain normal performance while ensuring effective EMP shielding. 6. Long‑term stability and high reliability. Deployed in critical infrastructure, protection circuits must maintain consistent performance throughout the full lifecycle without degradation after repeated pulse shocks, operating stably from −40 ℃ to +85 ℃. 7. Graded protection with redundancy. Single‑stage protection cannot absorb massive EMP energy and risks total failure if components degrade. Multi‑stage redundant architectures are required for progressive energy absorption and overvoltage clamping with backup safety. This methodology establishes a complete technical framework covering full‑spectrum graded protection, coupling path blocking, circuit‑level anti‑interference hardening, system shielding and grounding optimization, matching design verification and lifecycle reliability validation. It provides standardized guidelines for EMP hardening of high‑voltage power supplies against NEMP, LEMP and HPM. Adopting a four‑level comprehensive hardening system: port graded redundant protection + full‑link coupling suppression + circuit‑level anti‑interference reinforcement + system shielding and grounding optimization, supported by impedance matching, the framework overcomes traditional limitations in full‑spectrum coverage, nanosecond response, high surge tolerance and high‑voltage compatibility. Eight core design principles are defined: 1. Port graded redundant protection architecture. Independent four‑stage protection is implemented for power input, power output, signal and communication ports: primary high‑surge protection → decoupling fine filtering → secondary ultra‑fast clamping → terminal precision limiting. • Primary stage uses high‑energy GDTs, graphite gaps and MOVs to absorb major surge energy, clamping tens of kV down to several kA with parallel redundancy and current sharing. • Decoupling and multi‑stage π filtering delay pulse edges for secondary response and suppress high‑frequency HPM using high‑performance feedthrough capacitors. • Secondary ultra‑fast protection adopts ≤1 ns TVS, TSS and SIDACtor components to further clamp residual voltage, with series voltage sharing for high‑voltage compatibility. • Terminal precision limiting protects sensitive circuits with fast small‑signal clamping and RC/RLC spike absorption. • Special high‑voltage port protection uses series high‑voltage GDTs, MOV arrays and arc suppression circuits to prevent ignition and breakdown under high operating voltage. 2. Full‑link coupling path blocking. • Radiation shielding adopts fully sealed conductive enclosures with double copper‑steel layers for HPM, shielding effectiveness ≥80 dB from 10 kHz to 40 GHz. Seams use conductive gaskets; vents employ cutoff waveguide honeycomb structures; cable penetrations use filtered connectors and feedthrough capacitors. • Conduction suppression adds secondary filtering inside power, driver and sampling loops with snubbers and isolated drives to prevent internal cross‑coupling. • Grounding optimization separates power, analog, digital, shielding and protection grounds with single‑point star grounding. Independent low‑impedance surge discharge paths prevent ground potential rise. • Cable and PCB layout separates high‑power and low‑signal wiring by ≥30 cm; shielded cables achieve full 360° termination; multi‑layer PCBs integrate complete ground planes to minimize loop area and field coupling. 3. Circuit‑level anti‑interference hardening. • Power circuits adopt SiC MOSFETs/IGBTs with high dv/dt immunity plus RCD snubbers and low‑impedance laminated busbars. • Control circuits use industrial MCU/DSP/FPGA with multi‑stage power decoupling, hardened clock/reset circuits and triple modular redundancy (TMR) with voting logic against single‑event upset. Multi‑level watchdog systems enable automatic recovery. • Driver circuits implement magnetic or optical isolation with independent isolated power supplies to suppress pulse‑induced oscillation and false triggering. • Sampling circuits use differential amplification, shielded twisted pairs, low‑inductance precision resistors, oversampling and digital filtering to eliminate common‑mode interference. • Protection functions use fast hardware comparators with<1 μs response, independent from software, supplemented by software multi‑threshold anti‑false triggering logic. 4. System‑level electromagnetic shielding optimization. • Integrated welded metal housings ensure continuous conductivity; removable panels use beryllium copper springs or conductive rubber. • Internal sub‑shielding divides power, control and sampling zones; sensitive circuits apply double magnetic/electric shielding. • All apertures including ventilation, observation and operation ports adopt waveguide shielding and filtered feedthroughs. • All external cables use fully terminated shielded wiring; high‑voltage power cables apply double armor shielding. 5. Compatibility and impedance matching. Protection components and filter parameters are simulated and tuned to avoid resonance, waveform distortion and efficiency impact, especially optimizing parasitic effects on resonant soft‑switch topologies. Clamping levels strictly match rated operating voltage without static leakage or extra loss. High‑voltage sections adopt series voltage sharing and compact layout to suppress partial discharge and corona. 6. Wide‑temperature adaptability and long‑term reliability. All protection devices are rated −40 ℃ to +85 ℃ with ≥3× surge derating margins. Long‑life GDTs, high‑energy MOVs and military‑grade TVSs ensure stable performance after repeated shocks. Redundant parallel/series arrangements allow continued protection even if individual components degrade. PCB conformal coating and potting resist humidity, salt fog and corrosion. 7. Full‑digital fault tolerance and anti‑interference control. Critical logic and storage implement TMR and ECC error correction. Multi‑layer watchdog and hierarchical fault recovery handle transient interference with data filtering and automatic reset for severe anomalies. Real‑time full‑parameter monitoring detects EMP‑induced abnormalities and logs events for traceability. 8. Hierarchical verification system. Component‑level pulse surge, temperature and speed tests validate device performance. Circuit‑level simulation and surge/ESD/EFT/HPM irradiation tests optimize filtering and clamping. System‑level full NEMP, LEMP and HPM chamber certification verifies survivability without compromising normal power supply indicators. This methodology fundamentally solves traditional weaknesses including insufficient full‑spectrum coverage, slow response, limited surge capability and poor high‑voltage compatibility. The graded protection architecture achieves complete EMP shielding across kHz to tens of GHz; multi‑path coupling blocking eliminates interference penetration; circuit hardening and fault tolerance guarantee stable operation during severe pulses; and integrated shielding/grounding builds a robust electromagnetic security barrier. Widely applicable to industrial control, defense equipment, energy facilities, rail transit and communication systems, it delivers core technical support for reliable operation of high‑voltage power supplies in extreme strong electromagnetic pulse environments.