A space station is a long‑term orbiting national space laboratory hosting extensive scientific payloads for space life sciences, material sciences, microgravity physics and astronomical observation. Numerous precision instruments—such as particle detectors, surface analyzers, plasma experimental devices and high‑resolution imaging systems—require high‑voltage bias power supplies to deliver stable DC high voltage for particle acceleration, signal detection and electric field control. Power supply reliability and fault handling directly determine experimental continuity, data validity and station bus safety. Space station applications impose unique requirements: 1.Extreme power continuity: Long‑duration experiments demand uninterrupted operation with MTBF ≥ 1×10⁵ hours and redundant backup to avoid irreversible data loss from single failures. 2.Autonomous on‑orbit fault management: Most payloads are inaccessible to astronauts; power units must detect, isolate and switch redundancy autonomously within 1 ms without contaminating the station bus. 3.Multi‑channel wide‑range output: Voltage requirements span hundreds to tens of kilovolts; independent configurable channels are essential for diverse instruments. 4.Platform compatibility and safety: Strict adherence to station power standards, EMC regulations, thermal control and arc suppression is mandatory to prevent high‑voltage hazards. 5.Long‑term space environmental durability: External units must withstand high vacuum, thermal cycling, atomic oxygen and radiation with ≥10‑year operational life. This full‑process methodology covers redundant architecture, fault detection & isolation, autonomous switching, multi‑channel adaptation and station compatibility, providing standardized design principles for domestic space station scientific payloads. Adopting an N+X modular redundant framework with distributed control and hierarchical fault containment eliminates single‑point failure risks and wide‑ranging fault propagation typical of conventional power systems. The N+X architecture divides the system into N active modules and X hot/cold standby modules with fully interchangeable standardized designs. Active modules supply power under normal conditions; backup modules engage instantly upon failure while faulty units are electrically isolated. Five core principles apply: 1.Fine‑grained modularization enables independent single‑channel high‑voltage output with dedicated control, drive, conversion and protection; full electrical isolation prevents cross‑module interference. 2.Flexible redundancy configuration supports N+1 cold standby for general payloads and dual hot standby for critical long‑term monitoring, achieving zero interruption with full load transfer during faults. 3.Unified mechanical, electrical and communication interfaces ensure on‑orbit interchangeability and simplified astronaut replacement while reducing development costs. 4.Triple isolation on input, output and control sides with independent fuses, disconnectors and high‑voltage relays guarantees complete galvanic isolation of faulty modules. 5.Distributed local module controllers perform real‑time monitoring and protection; a dual hot‑backup system master controller coordinates redundancy switching, telemetry and commands to eliminate system‑level single failures. Hierarchical fault detection and isolation ensure rapid autonomous response: A three‑level mechanism—device‑level, module‑level and system‑level—achieves full fault coverage. Device‑level monitoring identifies component degradation in power switches, rectifiers, transformers and capacitors for early warning. Module‑level detection captures overvoltage, overcurrent, short circuits, overtemperature and waveform anomalies with dual hardware/software verification. System‑level monitoring oversees bus health, payload interfaces and station communication while classifying fault severity for graded response. Precise diagnostic algorithms localize faulty circuits and components with timestamped logs transmitted to ground for analysis and targeted astronaut maintenance. Fast isolation acts within 1 μs for severe faults via hardware shutdown, high‑voltage relay disconnection and fuse protection to safeguard the station bus; minor anomalies trigger adaptive parameter tuning without module disconnection. Seamless redundant switching guarantees uninterrupted power: Hot‑standby modules share load digitally with<0.5% voltage fluctuation and zero supply interruption during instant full‑load transfer. Cold‑standby units activate within 1 ms with <2% voltage drop, meeting general experimental requirements. Intelligent load balancing equalizes operational time across modules to extend overall service life; manual ground remote control supports flexible scheduling during experiments. Multi‑channel flexibility and station compatibility accommodate diverse payloads: Standard modules provide 100 V–30 kV continuously adjustable output at 10 W–500 W per channel, expandable to dozens of fully isolated independent outputs; parallel configuration boosts power for high‑demand instruments. Full compliance with the station’s 100 V bus (80 V–120 V operating range), EMI filtering, surge suppression and 1553B/CAN communication ensures seamless integration with onboard data systems. Optimized thermal design interfaces directly with station cold plates for stable component temperatures; double insulation, low leakage current (<10 μA) and fast arc detection/shutdown within 10 μA enhance fire safety. Low‑outgassing flame‑retardant materials, atomic oxygen coatings and radiation shielding ensure long‑term durability for external payloads. Comprehensive health monitoring and lifetime management secure decades of stable operation: Full‑parameter telemetry collects voltage, current, ripple, temperature, operational hours and switching cycles for real‑time ground oversight; non‑volatile memory archives up to 10 years of historical data for lifecycle traceability. Embedded health assessment algorithms evaluate module conditions, issue degradation warnings and predict remaining service life using reliability models to support maintenance planning and prevent unexpected experiment interruptions. In summary, this integrated framework resolves traditional limitations of single‑point failure, wide fault impact and poor maintainability. The N+X modular design delivers ultra‑high continuity; hierarchical fault mechanisms enable fully autonomous on‑orbit safety; standardized interchangeable modules support astronaut servicing and multi‑instrument compatibility. Fully compliant with space station regulations and extreme space environments, it provides essential domestic technical support for stable scientific payload operation and long‑term space research.