UPS Power Supply BOM: Full-Link Component Selection from AC Input to DC Output
UPS (Uninterruptible Power Supply) serves as fundamental infrastructure for industrial facilities and data centers. It receives alternating current from the utility grid as input and delivers power to loads at its output, passing through multiple intermediate stages including rectification, inversion and energy storage—each stage relies on dedicated electronic components to function.
Today we will break down a typical UPS BOM to analyze what components are required at every node from AC input to DC output, as well as the matching solutions offered by Heketech.
Basic Architecture of UPS Power Supplies
Mainstream UPS systems fall into two categories: online double-conversion UPS and line-interactive UPS. Their core difference lies in whether the inverter operates continuously. This discussion focuses primarily on online double-conversion UPS, as it consumes more components and imposes stricter component selection standards.
Basic topology: AC Input → Rectifier Bridge → DC Bus → Inverter → AC Output, with additional modules for battery charge/discharge management and bypass switching integrated in the circuit.
Component selection for every stage must take the following factors into account: voltage withstand margin, power margin, efficiency and reliability. As UPS units function as critical fail-safe equipment, component selection cannot be compromised.
AC Input Terminal: Rectification and Surge Protection
Rectifier Bridge: The First Step of AC-DC Conversion
After AC power enters the system, it first flows through a rectifier bridge to convert alternating current into pulsating direct current. Two key parameters govern rectifier bridge selection: rated current and reverse voltage withstand.
Given the high power rating of UPS systems, rectifier bridges typically start at a rated current of 10A, with a minimum voltage withstand rating of 600V to accommodate grid voltage fluctuations and surges.
Recommended Heketech Part Number: GBP04 (Rectifier Bridge)
GBP04 is a rectifier bridge with a 1000V voltage withstand rating. Its average forward current IF(AV) of 4A meets the requirements for low-power UPS systems, while GBP06 or GBP08 are recommended for high-power UPS models. Adequate voltage margin eliminates operational risks caused by grid voltage fluctuations.
Surge Protection: Prevent Equipment Damage from Lightning Strikes
UPS units are usually installed inside power distribution cabinets and must withstand grid surges and lightning impulse currents. TVS diodes or varistors are required at the AC input for surge protection.
DC Output Stage: Synchronous Rectifier MOSFETs
Synchronous Rectification: Core Technology for Higher Efficiency
Synchronous rectification topologies are widely adopted at the UPS output stage. Replacing conventional diodes with MOSFETs for rectification improves power efficiency by 2 to 3 percentage points.
Key criteria for selecting synchronous rectifier MOSFETs include low RDS(on), low gate charge (Qg) and moderate voltage withstand rating. Although UPS output voltages are commonly 220V or 380V, the MOSFETs mainly bear the secondary voltage of transformers, so devices rated at 600V are generally sufficient.
Recommended Heketech part number: HKTD80N06
Wait a minute, are 60V MOSFETs suitable for UPS applications? The answer is yes. The secondary-side rectification voltage of UPS equipment is relatively low, so 60V-rated MOSFETs are more than adequate. With an 80A current rating and an RDS(on) of 3.5mΩ, they guarantee high efficiency for synchronous rectification.
Battery Management: Charge Protection and Discharge MOSFETs
Battery Charging Management
Lead-acid batteries or lithium battery packs deployed in UPS systems require dedicated charging management circuits to avoid battery damage from overcharging. This circuit segment typically adopts specialized charging management ICs paired with power components.
Battery Discharge MOSFETs
MOSFETs are used to switch on and off the battery discharge loop. Key selection criteria are as follows:
- Withstand voltage: Minimum 1.5 times the nominal battery voltage to reserve sufficient safety margin
- Current capacity: Support peak discharge current, usually 2 to 3 times the rated battery capacity
- RDS(on): Low on-resistance to minimize power loss during discharge
60V MOSFETs are chosen for 48V battery systems, 100V MOSFETs for 96V systems, and so on. The HKTD80N06 features an 80A current handling capability, which fully meets the discharge requirements of 48V/20Ah batteries.
Full-Link TVS Protection: Both ESD and Surge Protection Are Indispensable
SMAJ24A: Universal protection for input and output ports
The SMAJ24A features a 24V standoff voltage that covers the protection requirements of 48V battery systems, and its 400W peak power rating can withstand most surge conditions. It is applicable to input ports, output ports and communication interfaces, serving as a versatile protection component for UPS equipment.
Summary of Full-Link UPS BOM
Combining all the above components forms the typical BOM of a UPS power supply:
Advantages of One-Stop Sourcing
UPS power supplies require a wide variety of components with diverse specifications. Separate procurement leads to cumbersome account reconciliation and difficult lead time coordination. The benefits of one-stop sourcing directly from the manufacturer are as follows:
- Controllable lead times: Heketech operates manufacturing facilities across three locations with an annual capacity of 50 billion components, ensuring consistent stock availability for standard part numbers.
- Optimized parameter matching: Compatibility between different components has been internally verified, reducing design risks.
- Professional technical support: In-house engineers provide holistic solution recommendations instead of merely supplying discrete components.
- Reliable traceability: In the event of quality defects, customers can liaise directly with the manufacturer without lengthy disputes with distributors.
Component Selection Recommendations
Solutions tailored to specific application scenarios are listed below:
- Low-power UPS (1–3 kVA): Adopt GBP04 for AC rectification, HKTD80N06 for secondary-side synchronous rectification and battery management circuits, and SMAJ24A for port surge protection. This three-part set fulfills all core circuit requirements.
- Medium-power UPS (10–20 kVA): Larger power derating margins are required. Select GBP08 or GBP10 rectifier bridges; multiple MOSFETs may need to be paralleled for synchronous rectification, and the manufacturer can offer reference designs for parallel connection schemes.
- High-power UPS (30 kVA and above): It is recommended to coordinate with Heketech’s engineering team for customized component selection based on your specific circuit topology.
UPS systems are mission-critical equipment, so extreme caution must be exercised during component selection. Components of identical ratings may exhibit batch-to-batch variations. Full performance validation is mandatory prior to mass production.