Industrial battery chargers are critical for powering applications ranging from power tools and medical devices to heavy machinery and electric vehicles (EVs). These chargers must operate in harsh environments, support diverse power sources (120–480 Vac), and prioritize compact size, lightweight design, and efficient cooling. The Power Factor Correction (PFC) stage is pivotal in achieving these goals, ensuring efficient power utilization from the AC mains while minimizing harmonic distortion. onsemi, a leader in power management solutions, is driving innovation in this space with its advanced Silicon Carbide (SiC) and Gallium Nitride (GaN) technologies. This blog post explores the topologies and components of PFC stage design for industrial battery chargers, highlighting onsemi’s transformative contributions and their impact on the industry.

The Role of PFC in Industrial Battery Chargers

The PFC stage is the front-end of an industrial battery charger’s architecture, converting AC input from the grid into a stable DC output while maintaining high efficiency and low harmonic distortion. By aligning input voltage and current waveforms, PFC maximizes power transfer, reduces energy waste, and ensures compliance with standards like IEC 61000-3-2 for harmonic content. This is crucial for industrial applications handling high power levels (600W to 6.6kW) and supporting battery chemistries like lithium-ion (12V–120V), which dominate use cases such as material handling equipment and EVs.

Why PFC Matters

1. Efficiency: A high power factor (close to 1) minimizes energy costs and heat generation.
2. Regulatory Compliance: PFC reduces Total Harmonic Distortion (THD), meeting global standards.
3. System Reliability: Efficient power conversion enhances charger longevity.
4. Compact Design: Advanced PFC designs enable smaller, lighter chargers for portable and space-constrained applications.

onsemi’s expertise in PFC solutions, from controllers to wide-bandgap (WBG) semiconductors, is enabling manufacturers to meet these demands with cutting-edge performance.

Key PFC Topologies for Industrial Chargers

The choice of PFC topology impacts charger performance, cost, and efficiency. Below, we explore two primary topologies—Boost PFC and Totem Pole PFC—emphasizing onsemi’s tailored components and controllers that enhance their effectiveness.

1. Boost PFC Topology

The Boost PFC topology is valued for its simplicity and reliability, consisting of:

1. EMI Filter: Suppresses electromagnetic interference.
2. Bridge Rectifier: Converts AC to pulsating DC.
3. Boost Inductor and FET: Steps up voltage to a stable DC level.
4. Boost Diode: Ensures unidirectional current flow.

onsemi’s Contributions:

1. Controllers: onsemi’s NCP1654 and NCP1655 controllers optimize power factor and minimize THD, offering robust performance for single-phase applications. For high-power chargers (>2kW), the FAN9672/FAN9673 supports interleaved Boost PFC, reducing ripple current and boosting efficiency.
2. Diodes: onsemi’s 650V EliteSiC diodes deliver low forward voltage drop, enhancing efficiency.
3. Switches: For high-power (2kW–6.6kW) applications, onsemi’s SiC MOSFETs, such as the NTH4L032N065M3S, provide low switching losses and high thermal tolerance. For lower power (600W–1kW), onsemi’s Silicon Superjunction MOSFETs or IGBTs operate effectively at 20kHz–60kHz.

Advantages:

1. Simple design with fewer components, reducing cost.
2. Reliable for a wide range of power levels.
3. Enhanced by onsemi’s ecosystem of controllers and WBG components.

Challenges:

1. Efficiency is limited by rectifier losses.
2. Component stress increases at higher power levels.

Impact: onsemi’s Boost PFC solutions balance cost and performance, making them ideal for cost-sensitive applications while leveraging SiC for improved efficiency.

2. Totem Pole PFC Topology

The Totem Pole PFC topology eliminates the bridge rectifier, offering superior efficiency for high-power applications. Its components include:

1. EMI Filter: Reduces noise.
2. Boost Inductor: Regulates current.
3. High and Low-Frequency Half-Bridges: Enable bidirectional power flow.
4. Gate Drivers and PFC Controller: Manage switching.

onsemi’s Contributions:

1. Controllers: The NCP1681 totem pole PFC controller supports high-frequency operation and integrates GaN drivers for compact designs. It’s optimized for Totem Pole PFC, delivering efficiencies up to 99%.
2. High-Frequency Leg: onsemi’s SiC MOSFETs (e.g., NTH4L032N065M3S for 3kW, NTH4L015N065SC1 for 6.6kW) or GaN devices excel in 600W–1.2kW applications due to low reverse recovery time. Integrated GaN drivers enhance performance in lower-power ranges.
3. Low-Frequency Leg: onsemi’s Silicon Superjunction MOSFETs or low VCE(SAT) IGBTs support 20–40kHz operation.
4. High-Power Configurations: onsemi’s SiC Cascode JFETs (e.g., UJ4SC075009K4S) enable interleaved Totem Pole PFC for 4.0kW–6.6kW, maximizing efficiency.

Advantages:

1. Achieves 98–99% efficiency by eliminating rectifier losses.
2. Supports bidirectional operation (e.g., vehicle-to-grid, V2G) for EV chargers.
3. Reduces common-mode current and input ripple for compact designs.

Challenges:

1. Requires complex control schemes and advanced MCUs.
2. Higher initial cost due to WBG components.

Impact: onsemi’s Totem Pole PFC solutions, powered by SiC and GaN, are ideal for high-efficiency, high-power chargers, particularly in EVs and industrial systems, setting new industry standards.

onsemi’s Leadership in SiC and GaN for PFC Design

onsemi is at the forefront of the WBG revolution, providing SiC and GaN solutions that transform PFC stage design:

1. SiC MOSFETs: onsemi’s EliteSiC MOSFETs (e.g., NTH4L032N065M3S, NTH4L015N065SC1) excel in high-power (1.5kW–6.6kW) applications, offering low switching losses, high thermal conductivity, and robustness in harsh environments. These are critical for Totem Pole PFC in EV chargers.
2. GaN Devices: For lower-power (600W–1.2kW) and high-frequency applications, onsemi’s GaN solutions with integrated drivers (e.g., in the NCP1681 controller) enable ultra-fast switching and compact designs, ideal for portable chargers.
3. Efficiency Gains: onsemi’s WBG devices achieve efficiencies of 98–99%, compared to 95–97% for Silicon-based designs, reducing energy costs and cooling needs.
4. Reliability: SiC and GaN’s high-temperature and voltage tolerance enhance charger longevity in industrial settings.
5. Innovation Ecosystem: onsemi’s comprehensive portfolio, including controllers like NCP1654 and FAN9673, and design tools, streamlines PFC implementation, reducing development time.

Challenges:

1. Cost: SiC and GaN are pricier than Silicon, though onsemi’s economies of scale are driving cost reductions.
2. Design Complexity: High-frequency WBG designs require precise EMI management and advanced MCUs, which onsemi addresses with integrated solutions.

Industry Impact: onsemi’s SiC and GaN innovations are accelerating the shift to efficient, compact chargers, positioning the company as a leader in EV, industrial, and renewable energy markets.

Broader Impacts on the Industrial Charger Market

Advancements in PFC design, powered by onsemi’s technologies, are reshaping the $3 billion industrial battery charger market, projected to grow at a CAGR of 8% through 2030:

1. Electric Vehicles: onsemi’s Totem Pole PFC solutions enable V2G capabilities, allowing EVs to stabilize grids and generate revenue for owners.
2. Sustainability: High-efficiency PFC reduces energy waste, aligning with regulations like the EU’s Ecodesign Directive.
3. Compact Solutions: onsemi’s SiC and GaN devices enable smaller, lighter chargers, critical for portable tools and space-constrained environments.
4. Cost Savings: Higher efficiency lowers operational costs, while compact designs reduce manufacturing expenses.
5. Market Leadership: onsemi’s WBG portfolio gives it a competitive edge, driving adoption in high-growth sectors like EVs and renewable energy.

Challenges and Future Directions

Despite the promise of onsemi’s PFC solutions, challenges remain:

1. Cost Barriers: SiC and GaN’s higher costs limit adoption in budget-conscious markets, though onsemi’s scaling efforts are narrowing the gap.
2. Supply Chain Constraints: Semiconductor shortages could impact SiC and GaN availability, requiring robust foundry partnerships.
3. Design Expertise: Complex topologies like Totem Pole PFC demand skilled engineers, which onsemi mitigates with comprehensive design resources.

Future directions include:

1. Hybrid Topologies: Combining Boost and Totem Pole PFC with converters like SEPIC or LLC for broader efficiency.
2. AI Integration: AI-driven control algorithms could optimize PFC performance dynamically.
3. Cost Reduction: onsemi’s ongoing investments in SiC and GaN production will lower costs, broadening adoption.
4. Sustainability Focus: PFC advancements will support renewable energy integration, such as solar-powered chargers.

Conclusion

The PFC stage is the cornerstone of industrial battery chargers, enabling efficient, reliable, and compact power solutions for a rapidly growing market. onsemi’s leadership in Boost and Totem Pole PFC topologies, powered by its EliteSiC MOSFETs, GaN devices, and advanced controllers like NCP1681, is driving a new era of charger design. These innovations deliver efficiencies up to 99%, supporting applications from EVs to heavy machinery while aligning with global sustainability goals. As challenges like cost and complexity are addressed, onsemi’s solutions will continue to shape the future of industrial charging, powering a connected, electrified world. Engineers and manufacturers should leverage onsemi’s design tools and expertise to build the next generation of high-performance chargers.