Commercial air purification and electrostatic dust removal equipment are the core equipment for indoor air treatment in office buildings, hospitals, hotels, shopping malls, rail transit, industrial factories and other commercial scenarios. A high-voltage electric field is formed between the discharge electrode and the collecting electrode through a high-voltage power supply, charging pollutants such as dust, particulate matter, aerosols, bacteria and viruses in the air. These pollutants are adsorbed onto the collecting electrode under the action of electric field force. Meanwhile, the molecular structures of bacteria and viruses can be destroyed to realize sterilization and disinfection. With the core advantages of low wind resistance, high dust removal efficiency, reusability, no consumable loss, and integrated sterilization & disinfection, it has become the mainstream technical route in the commercial air treatment field. The high-voltage power supply is the core power component of commercial electrostatic dust removal and air purification equipment. It provides stable high-voltage DC output for the electrostatic dust removal electric field, undertaking the core functions of electrostatic field construction, particle charging and dust removal efficiency regulation. Its conversion efficiency, output stability, ozone suppression capability, long-term operation reliability, environmental adaptability and intelligent regulation capability directly determine the dust removal efficiency, sterilization & disinfection effect, ozone emission, energy consumption, service life of air purification equipment, as well as indoor air quality and personnel health safety. Commercial air purification and electrostatic dust removal scenarios put forward differentiated technical requirements and core challenges for high-voltage power supplies, which are completely different from household purification power supplies and industrial dust removal power supplies. First, the requirement for extreme high efficiency and low energy consumption. Commercial air purification equipment usually operates continuously for 24 hours without interruption, with an annual operating time exceeding 8,000 hours. The energy consumption of the equipment directly determines the operating cost of commercial scenarios. Meanwhile, the state has strict energy efficiency standards for commercial electrical appliances, requiring the peak conversion efficiency of the power supply ≥92%, the average efficiency ≥88% in the full load range of 10%~100%, and standby power ≤1W, so as to minimize the energy consumption of the equipment and meet the national Class 1 energy efficiency standard. Traditional power-frequency high-voltage power supplies feature low efficiency and high energy consumption, which cannot adapt to the low energy consumption demand of long-term continuous operation of commercial equipment at all. Second, the strict requirement for low ozone generation and control. During electrostatic dust removal, corona discharge at the high-voltage discharge electrode ionizes oxygen in the air to generate ozone. Ozone is a strongly oxidizing gas; excessive ozone will irritate the human respiratory tract, causing sore throat, chest tightness and cough, inducing bronchitis and emphysema, and also causing oxidative corrosion to indoor furniture and decoration materials. The national standard GB/T 18801 for air purifiers clearly stipulates that the ozone emission of air purifiers ≤0.05mg/m³. In commercial scenarios with dense crowds and continuous equipment operation, the control requirement for ozone emission is more stringent. It is required to suppress ozone generation to the maximum extent on the premise of ensuring dust removal efficiency, and keep the ozone emission of the equipment far below the national standard limit. Third, the requirement for wide-range adjustable and high-stability output. In commercial scenarios, indoor air quality, personnel flow and dust concentration change greatly, and different pollution conditions require different high voltage for dust removal electric fields. It is required that the output voltage of the power supply can be continuously adjusted within the range of 4kV~15kV, with multiple output modes of constant voltage, constant current and constant power. It can automatically adjust output parameters according to changes in dust concentration and electric field load to maintain the stability of the electrostatic field, ensuring the optimal dust removal efficiency under different pollution conditions. Meanwhile, the output voltage stability is better than ±1%, to avoid the decline of dust removal efficiency and the increase of ozone generation caused by voltage fluctuation. Fourth, the requirement for long-term continuous operation with high reliability and long service life. Commercial air purification equipment needs to operate continuously 24 hours a day for 365 days. Most of them are installed in unattended computer rooms, office buildings and shopping malls, with long maintenance cycles and high maintenance costs. It is required that the mean time between failures (MTBF) of the power supply ≥5×10⁴h, and the design life ≥10 years. Meanwhile, it is equipped with complete fault self-diagnosis and self-recovery functions, which can cope with various abnormal working conditions such as electric field short circuit, arcing, overload and dust accumulation, and prevent equipment shutdown caused by single-point failure. Fifth, the requirement for strong environmental adaptability and load adaptability. The application scenarios of commercial air purification equipment are complex and diverse, facing wide temperature range changes of -10℃~+55℃, wide humidity range of 10%~95% RH, as well as harsh working conditions such as high dust, heavy oil fume and corrosive gas. In addition, the load of the dust removal electric field will fluctuate greatly with the change of dust accumulation thickness, humidity and dust properties, and even faults such as short circuit, arcing and sparking may occur. The power supply is required to have strong environmental adaptability to work stably under various harsh working conditions, as well as strong load adaptability to cope with wide-range changes of electric field load and abnormal faults. Sixth, the requirement for low electromagnetic interference and electromagnetic compatibility. Commercial air purification equipment is mostly installed in crowded places such as office buildings, hospitals and hotels, surrounded by a large number of sensitive electronic equipment such as computers, printers, medical equipment, communication equipment and security equipment. The power supply is required to meet the standards GB/T 17626 and GB 4343.1, with extremely low conducted and radiated electromagnetic interference, so as not to interfere with surrounding sensitive electronic equipment. Meanwhile, it has strong anti-electromagnetic interference capability to work stably in the complex electromagnetic environment of commercial scenarios. Seventh, the requirement for intelligent control and networking functions. Commercial air purification equipment usually needs to be connected to building automation systems and IoT platforms to realize centralized monitoring and intelligent management. The power supply is required to be equipped with complete communication interfaces and intelligent control functions, realizing remote adjustment of output parameters, real-time monitoring of operating status, fault early warning and reporting, automatic cleaning reminder for dust removal, and multi-machine linkage control, so as to adapt to the intelligent management needs of commercial scenarios. Eighth, the requirement for fire retardance and safety protection. As electrical products used in public places, commercial equipment has strict safety requirements. The power supply is required to be equipped with complete protection functions against overvoltage, overcurrent, short circuit, over temperature, electric arc and sparking. All materials adopt V-0 grade or above flame retardant materials, with double insulation and electric shock protection, complying with GB 4706.1 General Safety Requirements for Household and Similar Electrical Appliances and relevant safety standards for commercial electrical appliances, to prevent safety accidents such as fire and electric shock. Based on the core working condition requirements and technical challenges of high-voltage power supplies for commercial air purification and electrostatic dust removal equipment, this methodology forms a full-process general technical framework covering high-efficiency topology design, full-link ozone suppression, high-stability output control, long-term reliability design and intelligent management. It can adapt to the high-voltage power supply demands of various commercial electrostatic dust removal, air purification and oil fume purification equipment, and provide standardized design criteria for the localization and performance improvement of core components of domestic commercial air treatment equipment. Aiming at the core design challenges of high efficiency, low ozone, high reliability, long service life and intelligence in commercial purification scenarios, this methodology adopts the general design framework of "Active Power Factor Correction + Half-bridge LLC Resonant Soft Switch Topology + Full-digital Constant Voltage & Constant Current Control Architecture", combined with a full-link ozone suppression system and intelligent management system. It completely breaks through the technical bottlenecks of traditional power-frequency power supplies such as low efficiency, large ozone generation, poor reliability and high energy consumption. The core selection logic of the half-bridge LLC resonant topology is that it can realize Zero Voltage Switching (ZVS) of the primary power switches and Zero Current Switching (ZCS) of the secondary rectifier diodes in a wide input voltage range and wide load range, with extremely low switching loss, high efficiency and low electromagnetic interference, which is very suitable for the low energy consumption demand of long-term continuous operation of commercial equipment. Combined with the active power factor correction unit, the power factor can be increased to more than 0.99, reducing harmonic loss and meeting national energy efficiency standard requirements. Through the full-digital control architecture, multiple output modes of constant voltage, constant current and constant power can be flexibly switched, and the corona discharge intensity can be precisely controlled to suppress ozone generation to the maximum extent. The design shall follow eight core principles: 1. High-efficiency and low-loss topology design Aiming at the low energy consumption demand of long-term continuous operation of commercial equipment, optimize the topology and core parameters to realize high-efficiency operation under all working conditions, following three core criteria: ① Optimization design of Active Power Factor Correction (APFC) unit: Adopt Critical Conduction Mode Boost APFC topology, adapting to the wide input voltage range of 85VAC~265VAC, compatible with grid voltages in different regions worldwide. Realize unit power factor operation in the full load range with power factor ≥0.99 and Total Harmonic Distortion (THD) ≤10%, meeting GB 17625.1 harmonic standard. Optimize APFC parameters to realize soft switching, reduce switching loss, with conversion efficiency ≥97%. ② Optimization design of half-bridge LLC resonant topology: Combine fundamental wave analysis and time-domain simulation to optimize parameters of resonant cavity including magnetizing inductance, resonant inductance and resonant capacitance. Set normalized gain range 0.8~1.3 and quality factor Q=0.5~0.8, ensuring operation in the inductive region in the full input voltage range of 85VAC~265VAC and full load range of 10%~100%, realizing ZVS of primary switches and ZCS of secondary rectifiers to completely eliminate hard switching loss. The peak conversion efficiency of the whole machine ≥92%, and the average efficiency ≥88% in the load range of 20%~100%, minimizing energy consumption and meeting national Class 1 energy efficiency standard. ③ Optimization design of high-voltage rectification and filtering unit: Adopt full-wave rectification topology, select fast recovery diodes or SiC Schottky diodes with low forward voltage drop and low reverse leakage current to reduce conduction loss and reverse loss in the rectification link. Design multi-stage π-type filtering network at the output end, adopt low-ESR and low-loss polypropylene film capacitors to reduce filtering loss and realize low-ripple output, with peak-to-peak output voltage ripple lower than 0.5%, avoiding abnormal discharge and increased ozone generation caused by voltage ripple. 2. Full-link ozone suppression system design This is the core index of commercial purification power supply. Based on the ozone generation mechanism in electrostatic dust removal, build a full-link ozone suppression system from four dimensions: electric field control, topology optimization, parameter matching and discharge mode optimization, ensuring the ozone emission of the equipment is far below the national standard limit, following four core criteria: ① Precise discharge mode control: Ozone generation is directly related to corona discharge intensity, discharge type and electric field strength. Adopt full-digital closed-loop control to accurately control the working voltage of the electrostatic field within the optimal range between ignition voltage and breakdown voltage, avoiding excessive discharge, spark discharge and arc discharge to reduce ozone generation at the source. Optimize the current density of the electric field, control the corona current density of the discharge electrode below 0.1mA/m, and minimize corona discharge intensity and ozone generation on the premise of ensuring particle charging efficiency. ② Ozone suppression by high-frequency topology: Adopt high-frequency LLC resonant topology with switching frequency increased to 50kHz~100kHz. Compared with traditional 50Hz power-frequency power supplies, high-frequency high-voltage output can achieve the same particle charging efficiency at a lower average voltage. Meanwhile, the high-frequency electric field can inhibit the ionization of oxygen, greatly reducing ozone generation by more than 60% compared with power-frequency power supplies. ③ Suppression of output ripple and spike: High-voltage ripple and spike pulses will cause instantaneous overvoltage in the electric field, triggering abnormal discharge and greatly increasing ozone generation. Adopt multi-stage π-type filtering network and RC spike absorption circuit to suppress peak-to-peak output voltage ripple below 0.5%. Optimize the layout of the high-voltage circuit, shorten the high-voltage wiring length, reduce parasitic parameters, and suppress voltage spikes and oscillations to avoid increased ozone caused by abnormal discharge. ④ Load-adaptive ozone optimization control: Built-in dust concentration, humidity and temperature sensors to real-time monitor environmental parameters and electric field load status. Automatically adjust output voltage and current according to dust concentration, air humidity and electric field dust accumulation, maintaining optimal dust removal efficiency under various working conditions while keeping ozone generation at the lowest level. For example, automatically reduce output voltage in high humidity environment to avoid arc discharge and sharp ozone increase caused by high humidity; automatically reduce output power in low dust concentration environment to reduce ozone generation and energy consumption while ensuring purification effect. 3. Wide-range adjustable multi-mode output control design Aiming at complex and variable pollution conditions in commercial scenarios, adopt full-digital DSP control architecture to realize flexible switching and wide-range precise adjustment of constant voltage, constant current and constant power modes, following three core criteria: ① Full-digital dual closed-loop control architecture: Adopt dual closed-loop control of current inner loop and voltage outer loop, collect output voltage and current signals in real time through high-speed ADC, and realize full-digital PID control via DSP. The output voltage can be continuously and linearly adjusted within 4kV~15kV with adjustment accuracy better than ±0.5% and output voltage stability better than ±1%. Flexible setting of constant current and constant power thresholds realizes automatic switching of multiple modes to adapt to different working conditions. ② Load-adaptive dynamic adjustment algorithm: Real-time monitor electric field load impedance, spark discharge and arcing, establish an electric field load model. Automatically adjust control parameters and output characteristics when load fluctuates caused by dust accumulation, humidity change and dust property change, maintaining electrostatic field stability to ensure no decline in dust removal efficiency and avoid spark discharge and sharp ozone increase. ③ Intelligent spark and arcing processing algorithm: Built-in high-speed spark detection circuit can detect spark discharge, arcing and short-circuit signals of the electric field within 1μs. Adopt intelligent arc extinguishing algorithm to quickly reduce output voltage to extinguish sparks, then restore to normal working voltage quickly. The whole process is completed within 100μs, which not only prevents equipment damage and sharp ozone increase caused by continuous arcing, but also ensures the continuity of dust removal efficiency. Compared with traditional power supplies that shut down and restart when sparks occur, the dust removal efficiency can be increased by more than 30%, and ozone generation caused by spark discharge is greatly reduced. 4. Long-term continuous operation high reliability and long service life design Aiming at the demand of 24/7 continuous operation for commercial equipment all year round, build a four-level reliability design system of "component-level derating - circuit-level redundancy - system-level fault tolerance - full life cycle health management", following four core criteria: ① Extreme derating design: Implement extreme derating for all components. Voltage stress of power devices ≤50% of rated value, current stress ≤40% of rated value, temperature stress ≤60% of rated value; voltage stress of capacitors ≤50% of rated value; power stress of resistors ≤50% of rated value; working magnetic flux density of magnetic cores ≤30% of saturation magnetic flux density. Greatly reduce component working stress to avoid failure caused by over-stress and extend service life, ensuring design life of more than 10 years. ② Full-link redundancy design: Adopt dual redundancy design for control power supply, drive circuit, sampling circuit and protection circuit, realizing seamless switching in case of single-circuit failure to prevent equipment shutdown caused by single-point failure. Adopt parallel redundancy design for APFC and LLC resonant units to realize N+1 modular configuration. Single module can be automatically isolated in case of failure, and the remaining modules can work normally with derating to realize non-stop on-site maintenance, adapting to unattended continuous operation in commercial scenarios. ③ Full-dimensional protection design: Build a three-level non-bypassable protection system of "hardware fast protection - software closed-loop protection - system-level fault tolerance protection". Core protections such as overvoltage, overcurrent, short circuit, spark and over temperature are realized by high-speed hardware circuits with response time<1μs and the highest priority, which cannot be bypassed by software. Software protection realizes full-dimensional protection such as input over/under voltage, under voltage lockout, fan fault and ground fault. Design graded fault disposal mechanism: automatically recover from transient faults, operate with derating and send early warnings for persistent faults to avoid equipment shutdown, and shut down safely and report fault information for serious faults to ensure long-term continuous operation of equipment. ④ Full life cycle health management and fault early warning design: Built-in DSP-based health management system collects full-dimensional parameters such as input/output voltage & current, component operating temperature, fan speed, cumulative operating hours, spark times and fault events in real time. Evaluate the health status and remaining service life of the power supply through reliability models and machine learning algorithms, send early warnings for potential faults such as component performance attenuation, capacitor aging, fan failure and electric field dust accumulation, remind maintenance personnel of timely cleaning and maintenance, realize predictive maintenance, greatly reduce maintenance costs, reduce unplanned shutdowns, and ensure long-term stable operation of equipment. 5. Commercial complex environmental adaptability design Aiming at diverse application environments in commercial scenarios, build a full-dimensional environmental protection system, following four core criteria: ① Wide temperature adaptability design: Adopt industrial-grade wide-temperature components of -40℃~+85℃ for all parts, ensuring normal start-up and stable operation of the power supply within -10℃~+55℃, with output voltage fluctuation ≤±1% in the full temperature range. Design intelligent temperature control heat dissipation system to automatically adjust fan speed according to component temperature, reducing fan power consumption and noise while ensuring heat dissipation effect, and extending fan service life. Design over temperature protection: automatically operate with derating when internal temperature exceeds 85℃, and shut down safely when exceeding 100℃ to prevent component overheating damage. ② Three-proof protection design: Adopt fully sealed metal shell with protection grade above IP54. Internal PCB is coated with three-proof paint; all connectors adopt waterproof and dustproof industrial connectors. For application scenarios with high dust, heavy oil fume and corrosive gas such as oil fume purification and industrial factories, adopt IP65 protection grade and potting treatment for internal modules to isolate components from corrosion and pollution caused by dust, oil fume and corrosive gas, ensuring long-term stable operation in harsh environments. ③ Wide input voltage adaptation design: Optimize APFC and LLC topology parameters to ensure normal operation with input voltage of 85VAC~265VAC, compatible with global grid voltages. Equipped with grid voltage sag/swell and short-term power failure ride-through function, maintaining normal output within 200ms of short-term grid interruption to prevent equipment shutdown caused by grid fluctuation. ④ Vibration and impact resistance design: Adopt integrated metal shell; PCB is rigidly connected to the shell through multiple metal support columns; all heavy components are fixed by potting; connectors adopt anti-loosening design to withstand vibration and impact during transportation and installation of commercial equipment, ensuring stable structural and electrical performance. 6. Low electromagnetic interference and electromagnetic compatibility design Aiming at EMC requirements of commercial scenarios, build a full-link EMC design system of "source suppression - conducted filtering - radiation shielding - grounding optimization", following four core criteria: ① Source interference suppression: Realize full-condition soft switching through LLC soft switching topology, greatly reducing dv/dt and di/dt during switching to reduce electromagnetic interference at the source. Optimize power circuit layout, adopt laminated busbar design to shorten power circuit length, reduce circuit area and lower parasitic inductance and radiation interference. ② Conducted interference suppression: Design two-stage EMI filter circuit at the input end, including common mode filtering, differential mode filtering and spike suppression circuit. Adopt high-permeability nanocrystalline magnetic cores for common mode inductors to improve high-frequency filtering effect. Design high-voltage filtering and spike suppression circuit at the output end, and add RC/RCD buffer circuits at both ends of power devices and rectifiers to suppress switching spikes, ensuring conducted emission meets GB 4343.1 and GB 17625.1 standards. ③ Radiation interference suppression: Adopt fully sealed cold-rolled steel shielding shell with shielding efficiency ≥60%. Conductive gaskets are used at shell joints for continuous electrical connection to prevent electromagnetic leakage. Honeycomb waveguide structures are adopted for ventilation holes; power cables and signal cables adopt shielded cables with 360° double-ended grounding. Internal power unit and control unit are arranged in independent shielding cavities to avoid interference coupling from power circuit to control circuit, ensuring radiated emission complies with relevant standards. ④ Grounding and anti-interference optimization: Adopt star single-point grounding design; strictly separate power ground, analog ground, digital ground, shielding ground and chassis ground, converging at a single grounding point to avoid interference caused by grounding loops. Equipped with complete anti-interference protection circuits; anti-interference performance such as ESD, EFT, surge and RF induced conducted interference reaches Level 4 of GB/T 17625.1, enabling stable operation in complex commercial electromagnetic environments. 7. Intelligent control and networking function design Aiming at intelligent management demands of commercial scenarios, build a complete intelligent control and communication architecture, following three core criteria: ① Multi-sensor integrated intelligent regulation: Built-in dust concentration, temperature & humidity, VOC and electric field current sensors to real-time monitor indoor air quality and electric field operating status. Automatically adjust output power and operating mode according to indoor pollution level: full-power operation with high pollution, energy-saving operation with low pollution, minimizing energy consumption and ozone generation while ensuring purification effect. ② Rich communication interfaces and networking functions: Integrate RS485, CAN, Ethernet, WiFi, Bluetooth and other communication interfaces, supporting standard protocols such as Modbus and BACnet. Seamlessly connect to building automation systems and IoT platforms to realize remote monitoring, remote parameter configuration, fault reporting and remote firmware upgrade, as well as linkage control of multiple devices, adapting to centralized and intelligent management needs of commercial scenarios. ③ Humanized human-computer interaction design: Equipped with OLED display and keys to real-time display output voltage, current, operating hours, fault status and indoor air quality. Local setting of operating parameters and modes via keys; clear status indicators and fault alarm functions facilitate on-site equipment checking and fault troubleshooting. 8. Safety protection and compliance design Aiming at safety requirements of public commercial places, build a full-dimensional safety protection system and meet relevant national standards and industry specifications, following two core criteria: ① Full-dimensional safety protection design: Strictly comply with GB 4706.1 and GB 4706.45. Adopt double insulation and electric shock protection; insulation withstand voltage between input and high-voltage output ≥4000VAC. High-voltage output adopts fully sealed insulation design with no exposed high-voltage parts to prevent electric shock. All materials adopt V-0 grade or above flame retardant materials to eliminate open fire. Equipped with complete protection functions against overvoltage, overcurrent, short circuit, over temperature, electric arc, sparking and ground fault; all core protections adopt dual redundancy of hardware and software to quickly cut off output in case of any fault and protect equipment and personnel safety. ② Full compliance design: Strictly comply with GB/T 18801 air purifier standard, GB 4343.1 EMC standard, GB 17625.1 harmonic standard, GB 4706.1 safety standard and other national standards. Support rapid adaptation to international certifications such as EU CE, US UL and ENERGY STAR, meeting domestic and global market access requirements. Based on the core working condition requirements and technical challenges of high-voltage power supplies for commercial air purification and electrostatic dust removal equipment, this methodology forms a full-process general technical framework covering high-efficiency topology design, full-link ozone suppression, multi-mode intelligent control, long-term reliability design and intelligent management. It completely solves the core pain points of traditional power-frequency power supplies such as low efficiency, large ozone generation, poor reliability and high energy consumption. Adopt LLC soft switching topology to achieve overall conversion efficiency above 92%, meeting national Class 1 energy efficiency standards. Adopt full-link ozone suppression system to control ozone emission within 50% of the national standard limit. Adopt four-level reliability design system to realize MTBF above 5×10⁴h and design life above 10 years. Adopt full-digital intelligent control to realize multi-mode output and load adaptive adjustment, ensuring optimal dust removal efficiency under various working conditions. This methodology can be widely applied to high-voltage power supply demands of various electrostatic dust removal and purification equipment such as commercial air purifiers, fresh air systems, central air conditioning electrostatic dust removal modules, oil fume purification equipment and industrial waste gas treatment equipment, providing core technical support for the localization substitution and high-performance breakthrough of core components of domestic commercial air treatment equipment.