DC/DC Converters in Hydrogen Energy Systems: Key to Efficient Operation

DC/DC converters in hydrogen energy systems are critical components for efficient operation. Key points are as follows:

1.Core Function

Voltage Stabilization and Regulation: The output voltage of hydrogen fuel cells fluctuates with operating conditions. The DC/DC converter converts this voltage into a stable DC voltage to meet the needs of charging the power battery and supplying power to the high-voltage bus.

Power Matching: Addressing the soft output characteristics of fuel cells, the DC/DC converter adjusts the stack output voltage to the operating voltage range of high-voltage components such as the drive motor and air compressor through boost or buck functions.

Energy Management: Tracking the fuel cell's maximum power point (MPP) optimizes energy utilization while monitoring battery voltage and current to prevent overcharging or over-discharging.

Key Technologies for Efficient Operation

2.Topology Selection

Non-isolated: Such as a three-phase interleaved parallel boost circuit, this converter offers advantages such as high conversion efficiency, fast dynamic response, and compact size, making it the mainstream solution for automotive applications.

Isolated: This converter offers enhanced safety but is bulky and costly, making it suitable for applications with stringent electrical isolation requirements. Power Device Selection:

Silicon Carbide (SiC) Devices: Compared to traditional silicon-based IGBTs, SiC MOSFETs offer high switching frequencies (up to hundreds of kHz), low on-resistance, and high-temperature resistance, significantly reducing switching losses and boosting system efficiency to over 97%. Peak efficiency can reach 99% under certain operating conditions.

3.Control Strategy Optimization

A centralized system based on the hydrogen power system's energy management controller (ECU) implements functions such as input current limiting and output voltage tracking of bus voltage variations.

Digital control technology enables real-time monitoring of current and voltage to ensure peak performance under varying operating conditions.

4.Design Challenges and Solutions

Hydrogen Embrittlement Protection: Hydrogen-embrittlement-resistant inductors (such as an iron-based amorphous alloy core with titanium nitride coating) and vacuum epoxy resin potting are used to reduce the risk of core fracture caused by hydrogen atom penetration.

Low-Temperature Startup: An integrated NTC sensor and AI dynamic compensation algorithm, combined with low-temperature rise operation technology, ensure voltage fluctuations are controlled within ±0.8% at -40°C. Thermal Management: Matching high glass transition temperature (Tg) substrates, optimizing power module layout, and employing a liquid cooling system ensure stable device operation at high temperatures.

5.Industry Application Examples

Rail Transit: CRRC Electric's 300kW SiC-based DC/DC converter utilizes a three-phase interleaved parallel topology, achieving a peak efficiency of 97.8%, meeting high power and power density requirements.

Passenger Vehicles: The Hyundai Nexo's 80kW DC/DC module achieves a measured efficiency of 98.5% and supports a -40°C cold start.

Heavy Trucks: BrightLoop's 250kW SiC DC/DC module can be paralleled to achieve megawatt-level output and is compatible with 1200V/1500V high-voltage platforms.

In summary, DC/DC converters, through topology innovation, device upgrades, and intelligent control, address voltage instability and power matching challenges in hydrogen energy systems, making them one of the core technologies driving the commercialization of hydrogen energy technology.