In an Uninterruptible Power Supply (UPS) system, efficient power conversion and precise battery management are the two core pillars ensuring continuous power supply. Among them, the power board undertakes the "power conversion" responsibility for bidirectional AC/DC and DC/AC energy transformation, while the charging board is responsible for the "precise regulation" of battery charging and discharging. Their collaborative operation forms the technical foundation for the stable operation of UPS. This article will deeply analyze the value of these two core components from the perspectives of technical characteristics, functional logic, and practical applications.

1. Power Board: The "Power Core" of UPS, Supporting Efficient Power Conversion

The power board is the core carrier for UPS to realize power form conversion, and its performance directly determines the output quality, response speed, and operating efficiency of UPS. In UPS systems of different specifications, the power board usually exists as an independent module or integrated unit. Especially in modular UPS systems, the main power module is crucial for achieving rapid maintenance and redundant expansion.

(1) Essential Positioning and Integrated Architecture

The core value of the power board lies in integrating three functional units—"rectification, inversion, and drive protection"—to form an integrated power conversion system. Taking the Aipuwaton M Series Modular UPS as an example, its main power module highly integrates the rectifier, inverter, and battery charger/discharger into an independently pluggable unit. This design not only reduces the complexity of system wiring but also supports module replacement within 5 minutes, significantly reducing maintenance downtime. Such an integrated architecture not only improves space utilization but also ensures compatibility between different modules through standardized design.

(2) Core Composition and Technical Characteristics

The performance of the power board relies on the collaborative optimization of key components and circuit design, and the technical characteristics of each component directly affect the overall performance of UPS:

• Rectifier Unit: As the entry point for AC/DC conversion, the rectifier unit adopts a high-frequency Power Factor Correction (PFC) circuit and Silicon Carbide (SiC) diodes. It can increase the input power factor to ≥0.99 and control current harmonics within 3%, effectively reducing pollution to the power grid. Compared with traditional silicon-based components, the high-frequency characteristics and low-loss advantages of SiC diodes provide support for the high-frequency design of the power board, meeting the energy efficiency requirements of modern UPS.

• Inverter Unit: Acting as the "core engine" for DC/AC conversion, it uses Insulated Gate Bipolar Transistors (IGBTs) or SiC Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs) as switching devices, combined with a Sinusoidal Pulse Width Modulation (SPWM) chip to achieve precise waveform control. In online UPS, the inverter unit operates continuously, capable of controlling the Total Harmonic Distortion (THD) of output below 2% with a switching time of ≤5ms, ensuring that precision loads such as servers and medical equipment receive stable and clean AC power. Taking the SiC MOSFET (e.g., model BMF240R12E2G3) as an example, its loss is reduced by more than 30% compared with traditional IGBTs, which not only improves conversion efficiency but also reduces heat dissipation pressure.

• Drive Protection Circuit: It adopts a dual Digital Signal Processor (DSP) controller and isolated drive chips to build a "dual protection" mechanism. The dual DSP design eliminates the risk of single-point failure and ensures the real-time performance and reliability of control commands; the isolated drive chips realize electrical isolation between power devices and control circuits, preventing damage to the core circuit caused by abnormal conditions such as overcurrent and overvoltage, and ensuring the stable operation of the power board under complex working conditions.

• Heat Dissipation Structure: Aiming at the high heat generation of the rectifier and inverter units, the power board adopts an "inverted PCB + directional heat sink" design, which separates sensitive control circuits from high-heat-generating components in layers and enhances heat dissipation through directional air ducts. This design allows the power board to adapt to a wide temperature range of -40℃ to 85℃, meeting the 24/7 continuous operation requirements of industrial scenarios. The application of SiC components further reduces heat loss, making fanless design possible for small UPS.

(3) Technical Evolution and Scenario Adaptation

With the diversification of load demands, power board technology continues to iterate to adapt to different scenarios:

• Component Upgrades Drive Topology Simplification: The popularization of SiC MOSFETs has simplified the topology of three-phase four-wire UPS from the traditional three-level to two-level, reducing the number of components by 50%. This not only lowers costs but also improves system reliability, making it suitable for high-power scenarios such as data centers.

• Topology Innovation for Unbalanced Loads: The power board of modular UPS adopts a "three-phase four-leg" structure, which independently regulates zero-sequence current through the fourth leg. Even under 100% unbalanced load conditions, it can control the output THD within 3%, perfectly adapting to the complex load demands of server clusters in AI computing data centers.

• Redundancy Design for High Availability: It supports N+X redundancy configuration. For example, when operating at 100% load, 20% redundant capacity is still reserved. If a power module fails, the redundant module can seamlessly take over, achieving a system availability of 99.999%, which meets the high requirements for continuous power supply in scenarios such as finance and medical care.

2. Charging Board: The "Battery Manager" of UPS, Enabling Precise Charging and Discharging Management

The charging board is the core hub connecting the mains power and the battery. It is responsible for charging the battery to store energy when the mains power is normal and cooperating with the battery to supply power to the load when the mains power is interrupted. Its management precision directly affects battery life and the emergency backup time of UPS. According to the power specifications and application scenarios of UPS, charging boards are mainly divided into two types: independent and integrated.

(1) Two Technical Types and Application Scenarios

• Independent Charging Board: A mainstream solution for industrial-grade UPS, characterized by high current and high compatibility. For example, the Aipuwaton 50A/2U high-capacity charging module adopts a standardized slot design, which is compatible with power modules and supports rapid replacement and capacity expansion. Its 50A high charging current can quickly restore battery capacity, while supporting the adaptation of different types of battery packs (e.g., lead-acid and lithium-ion batteries). It also allows software adjustment of charging parameters to meet the needs of high-power UPS (10-600kVA), and is widely used in scenarios such as data centers and industrial control systems. In addition, the independent charging board supports "old battery reuse" transformation, which can adapt to existing old battery packs and reduce the user's upgrade costs.

• Integrated Charging Board: A compact design solution for small UPS, with the core advantages of "small size and multi-function". For example, the 18650 lithium-ion battery UPS control board integrates the charging circuit and inverter control circuit into a micro-module of 33×17×4mm, with a volume only 1/5 of that of a traditional independent charging board. It supports simultaneous 5V/1A charging and discharging, which can not only charge the battery but also supply power to portable electronic devices such as mobile phones and routers, making it suitable for scenarios such as homes and small offices.

(2) Core Functions and Control Logic

The core of the charging board is to achieve the goal of "fast charging and extended lifespan" while ensuring battery safety through refined control strategies. Among them, "three-stage charging management" is the mainstream control logic:

1. Constant Current Stage: When the battery power is low, the charging board performs fast charging with a high current (e.g., 50A for independent modules) to quickly restore battery capacity and shorten charging time. During this stage, current closed-loop control is adopted to ensure stable charging current and avoid battery damage caused by current fluctuations.

2. Constant Voltage Stage: When the battery power reaches approximately 80%, the charging board switches to constant voltage mode, maintaining the rated battery voltage (13.5V per cell for lead-acid batteries, 3.65V per cell for lithium-ion batteries) for charging. This stage prevents overcharging of the battery, avoids electrolyte decomposition or lithium dendrite growth, and protects the internal structure of the battery.

3. Float Charging Stage: After the battery is fully charged, the charging board automatically switches to trickle float charging mode, using a small current to compensate for the battery's self-discharge loss and maintain the battery in a fully charged state. At the same time, the charging board integrates temperature compensation technology, dynamically adjusting the float voltage according to the battery temperature (e.g., the float voltage decreases by 3-5mV for every 1℃ increase in temperature), which can extend the battery life by more than 30%.

In addition, the charging board also has "intelligent linkage" capabilities: it communicates in real-time with the battery's Battery Management System (BMS) to monitor parameters such as battery cell voltage, temperature, and State of Charge (SOC). Once unbalanced cell voltage or abnormal temperature is detected, it immediately adjusts the charging current or triggers a thermal runaway warning; for lead-acid batteries, it adapts to battery packs of different capacities (e.g., 12V/7Ah, 12V/100Ah) through current adaptive adjustment, avoiding battery damage caused by mismatched charging parameters.

(3) Key Protection and Performance Indicators

To ensure the safety of the battery and system, the charging board builds a multi-layer protection system combining "hardware + software":

• Hardware-Level Protection: It integrates an input reverse connection prevention circuit to avoid short circuits caused by reverse connection of the battery's positive and negative terminals; it is equipped with a Transient Voltage Suppressor (TVS) diode to absorb input surge voltages (e.g., peak voltages caused by 220V mains fluctuations) and protect the charging chip; some high-end modules also use self-recovering fuses, which automatically blow in case of overcurrent and resume conduction after the fault is eliminated, without the need for manual replacement.

• Software-Level Protection: It sets an overcharge protection threshold (e.g., cutting off the charging circuit when the voltage of a single lithium-ion battery cell ≥4.2V) and an over-temperature protection threshold (forcing charging to stop when the ambient temperature ≥85℃). It also has an over-discharge protection function, which issues a warning when the battery power is below 10% to avoid battery damage caused by deep discharge.

In terms of performance indicators, there are significant differences between different types of charging boards: the charging efficiency of industrial-grade independent modules is ≥96%, with a wide adaptation range for battery pack voltages (e.g., 24V, 48V, 192V); the charging efficiency of small integrated boards is ≥80%, which, although lower in power, has the advantages of compact size and low cost, meeting the lightweight needs of portable devices.

3. Synergy Logic Between Power Board and Charging Board: Building the "Dual Core" for Stable UPS Operation

The power board and charging board do not work independently but are linked through the control circuit to form efficient synergy under different working conditions, ensuring the continuity and reliability of UPS power supply. The specific synergy logic can be divided into three scenarios:

(1) Normal Mains Power: Parallel "Power Supply + Energy Storage"

When the mains voltage and frequency are within the normal range, the rectifier unit of the power board converts 220V AC into stable DC power. A part of the DC power is transmitted to the charging board through the DC bus, and the charging board charges the battery according to the "three-stage" strategy; the other part is transmitted to the inverter unit of the power board, which converts it into 220V sinusoidal AC power. After waveform optimization by the filter module, the AC power is supplied to the load. At this time, the charging board monitors the battery status in real-time and dynamically adjusts the charging current to ensure fast battery energy storage while avoiding overcharging; the power board optimizes the input power quality through the PFC circuit to reduce interference to the power grid, realizing the simultaneous operation of "load power supply" and "battery energy storage".

(2) Mains Power Interruption: "Seamless Switching" for Power Supply

When the mains power is suddenly interrupted (e.g., power grid failure, power outage), the control circuit of the power board detects the mains abnormality within 10ms and immediately sends a command to the charging board to stop charging. The charging board quickly disconnects from the mains; at the same time, the battery discharges to the inverter unit of the power board through the DC bus, and the inverter unit maintains stable operation to convert the battery's DC power into AC power for the load. During this process, the dual DSP controller of the power board precisely controls the switching sequence, and the filter module ensures that the output voltage fluctuation is ≤±1%, realizing "zero-perception" switching and avoiding load restart caused by power outage or voltage fluctuation.

(3) Emergency Fault Condition: "Protection + Backup" Dual Guarantee

When a system fault occurs (e.g., IGBT short circuit in the power board, overcurrent in the charging board), the two components collaboratively trigger the protection mechanism: if the power board detects IGBT overcurrent or short circuit, it immediately activates the bypass switch to directly introduce mains power to the load, avoiding load power outage; at the same time, it sends a fault signal to the charging board, and the charging board cuts off the battery circuit through the BMS to prevent the battery from discharging to the faulty module and avoid secondary damage. If the charging board detects battery over-temperature or overcharging, in addition to cutting off the charging circuit itself, it also feeds back the status to the power board. The power board can adjust the output power according to the battery level to prioritize power supply for critical loads, achieving the dual goals of "fault isolation" and "load protection".

4. Application Value: "Technical Support" for Adapting to Diversified Scenarios

The technical characteristics of the power board and charging board directly determine the adaptability of UPS in different scenarios:

• Data Center Scenario: The power board of modular UPS supports N+X redundancy, and the charging board is compatible with large-capacity lithium-ion battery packs. Their collaboration can achieve 99.999% availability, meeting the 24/7 continuous operation needs of server clusters; the power board with a three-phase four-leg topology can also cope with the unbalanced load of servers, ensuring stable data processing.

• Industrial Scenario: The independent charging board is compatible with high-capacity lead-acid batteries and supports operation in a wide temperature range; the SiC components of the power board reduce losses, enabling long-term operation in high-temperature and high-dust industrial workshops, providing stable power supply for production line equipment.

• Portable Scenario: The miniaturized design of the integrated charging board and power board reduces the size of UPS to "palm-sized" (e.g., 18650 lithium-ion battery UPS), which can be carried around to provide temporary power supply for outdoor live broadcast equipment and emergency communication terminals, meeting the needs of mobile office and emergency rescue.

5. Conclusion

As the "dual core" of UPS, the power board and charging board respectively undertake the key responsibilities of "power conversion" and "battery management": through component upgrades and topology innovation, the power board realizes efficient and stable power conversion, adapting to different power needs from portable devices to data centers; through refined charging and discharging control and multi-layer protection, the charging board extends battery life and ensures emergency backup capability. Their collaborative operation builds a stable operation system for UPS under different working conditions (normal mains power, power interruption, fault), providing solid technical support for continuous power supply in various industries.

With the further popularization of SiC components and AI control algorithms, the power board and charging board will develop towards "higher efficiency, greater intelligence, and miniaturization" in the future. For example, the conversion efficiency of the power board is expected to exceed 98%, and the charging board can realize dynamic charging strategies through AI learning of battery attenuation rules. This will further improve the comprehensive performance of UPS and contribute to the high-quality development of fields such as new energy and the digital economy.