Digital Control Methodology for Low-Power Standby and Full-Condition Energy Efficiency Optimization of High-Voltage Power Supplies

Low-power standby and full-operating-range energy efficiency optimization are core performance indicators for high‑voltage power supplies under the dual-carbon goals, directly determining operational energy consumption, heat generation, long-term reliability and service life. Especially for emergency power supplies, medical power units, portable monitoring instruments that remain in standby most of the time, and industrial/new-energy power systems running continuously all year round, ultra-low standby power and full-condition efficiency are strictly required. Traditional high‑voltage power supplies only optimize efficiency at rated loads with extremely poor light-load performance and high standby consumption, failing to achieve overall energy-saving operation. Digital control, through intelligent topology management, mode switching and algorithm optimization, realizes optimal efficiency across all working conditions and ultra-low standby power, becoming the mainstream technical route for modern high‑voltage power supplies. Eight core challenges exist in this field.

First, ultra-low standby control. Emergency, portable and IoT high‑voltage power supplies require standby power ≤10 mW or even ≤1 mW. Conventional auxiliary power, control and sampling circuits keep consuming power during standby. Digital solutions must support partition power shutdown, low-clock management and intermittent wake-up to minimize quiescent loss. Second, full-range efficiency improvement. Load varies widely from no-load, 10% light load to full load. Traditional efficiency curves feature a single peak near rated power and drop sharply under light loads, while many applications operate mostly at low loads. Efficiency algorithms must maintain average efficiency ≥90% from 20% to 100% load and ≥85% even at 10% light load. Third, balancing efficiency and EMC. Faster switching reduces losses yet raises dv/dt and di/dt, worsening EMI. Adaptive digital tuning must guarantee EMC compliance while maximizing energy efficiency. Fourth, efficiency under wide input voltage. Grid fluctuations reach 60%–150% rated input; conventional designs degrade significantly off nominal voltage. Optimization must maintain high efficiency throughout the full input range. Fifth, full-condition soft-switching coverage. LLC and phase-shift full-bridge topologies lose soft-switching under light load or off-nominal input, causing sharp loss increases. Digital control must retain ZVS/ZCS even at 10% light load to eliminate hard-switch losses. Sixth, co-optimizing efficiency and reliability at high temperatures. Higher ambient temperature increases device loss and junction temperature, accelerating aging. Algorithms must dynamically adjust parameters based on temperature to balance efficiency and thermal safety. Seventh, smooth multi-mode transition. Seamless switching among PWM/PFM/burst modes or parallel module activation must avoid voltage fluctuation, oscillation and instability during transitions, with output deviation ≤±1%. Eighth, energy standard compliance. Products must meet GB 20943, IEC 62368, ENERGY STAR and other mandatory efficiency regulations for civil, medical and office equipment to achieve green energy-saving certification.

Addressing these challenges, the methodology establishes a universal framework: full-condition soft-switching digital control + intelligent multi-mode switching + ultra-low standby management + adaptive energy optimization. It achieves standby power ≤1 mW and average efficiency ≥90% from 20% to 100% load, breaking traditional bottlenecks of high standby consumption and poor light-load efficiency. The design follows eight core principles. First, ultra-low standby architecture adopts partition power supply, intermittent wake-up and low-frequency clock control. Circuits are divided into core standby, wake-up, main power and auxiliary sections. Main and auxiliary power are disabled during standby, retaining only low-power MCU circuits with standby current ≤1 μA and 32 kHz low-speed clock. Wake-up triggers include button, communication, timing and fault signals with response ≤100 μs. Periodic brief wake-up further reduces average standby consumption to ≤1 mW. Second, full-condition soft-switching optimizes resonant and phase-shift topologies. Mixed frequency-plus-phase-shift control ensures LLC maintains ZVS on primary and ZCS on secondary even at 10% light load. Adaptive dead-time and active clamping solve light-load soft-switch failure in phase-shift full-bridge circuits, greatly improving low-load efficiency. Third, disturbance-free multi-mode switching automatically selects PWM for heavy load, PFM for medium-light load and burst mode for ultra-light load. Smooth transition algorithms predict switching thresholds and adjust parameters dynamically, limiting voltage fluctuation ≤±1% without overshoot or ringing. Fourth, adaptive full-range energy optimization establishes real-time loss models using input voltage, load current, junction temperature and switching loss data. Optimization algorithms tune frequency, dead time and drive parameters to locate the lowest-loss operating point, achieving ≥90% average efficiency across 20%–100% load and stable performance under 60%–150% input voltage. Fifth, dynamic efficiency–EMC balancing adjusts switching speed, frequency dithering and drive strength based on real-time EMI monitoring. Heavy-load prioritizes efficiency with moderate dithering; light-load slows switching to suppress dv/dt/di/dt and optimize EMC while keeping losses low via PFM. Sixth, thermal synergy control monitors power device, transformer and ambient temperature. Junction-temperature closed-loop adjustment optimizes switching trajectories to reduce heat and maintain safe operating limits. Derated mode activates above 55 ℃ ambient temperature to extend service life. Seventh, cluster energy optimization for parallel systems dynamically determines the optimal number of active modules according to total load, avoiding long-term light-load operation. Rotational module runtime balances aging and improves overall system reliability and lifespan. Eighth, global energy standard compliance fully aligns with GB 20943, IEC 62368 and ENERGY STAR, adopting standardized efficiency templates for different industries. Environmentally friendly lead-free, halogen-free materials comply with RoHS and REACH to support low-carbon development under dual-carbon policies.