In the context of advancing eVTOL (Electric Vertical Take-Off and Landing) development and certification, robust and mobile ground support equipment (GSE) is critical for low-altitude navigation and flight testing. Mobile charging units, portable test bench power supplies, and ground power units (GPUs) act as the "energy lifeline" for test campaigns, requiring high power density for mobility, exceptional efficiency to minimize thermal footprint, and unwavering reliability in field environments. The selection of power MOSFETs is fundamental to achieving these goals. This article targets the demanding application of eVTOL test GSE—characterized by needs for wide input voltage range, high output power, dynamic load response, and operation in varying outdoor conditions—and provides an in-depth device selection analysis and optimized recommendation.
Detailed MOSFET Selection Analysis
1. VBP17R15S (N-MOS, 700V, 15A, TO-247, SJ_Multi-EPI)
Role: Primary switch in the front-end PFC or isolated DC-DC stage of a mobile charging unit.
Technical Deep Dive:
Voltage Robustness & Efficiency: The 700V rating provides a robust safety margin for universal input applications (85-265VAC) or three-phase 400VAC inputs after rectification (~565VDC). Utilizing Super Junction Multi-EPI technology, it offers an excellent balance between low on-resistance (350mΩ) and high voltage capability, directly reducing conduction losses in the critical first power conversion stage. This is essential for maximizing the runtime of generator-powered or battery-buffered mobile test units.
Power Scalability for Test Profiles: With a 15A continuous current rating, it is well-suited for medium-power GSE modules (15-30kW). The TO-247 package facilitates parallel operation and effective thermal interface with heatsinks, allowing power scaling to meet the demanding charge cycles and variable load profiles of eVTOL testing.
2. VBP16R87SFD (N-MOS, 600V, 87A, TO-247, SJ_Multi-EPI)
Role: Main switch in the high-power, non-isolated DC-DC stage or direct output stage for simulating and supplying high-current loads to eVTOL test benches.
Extended Application Analysis:
Ultra-Low Loss Power Delivery Core: Its exceptionally low Rds(on) of 26mΩ (at 10V Vgs) combined with a high 87A current rating makes it ideal for handling the high-current paths in test equipment. This minimizes conduction losses when delivering power to a test article's bus or when functioning as a synchronous rectifier in a high-power LLC converter, directly boosting system efficiency and reducing cooling demands.
Dynamic Response for Test Scenarios: The low gate charge inherent to its SJ technology enables higher frequency switching, allowing for faster control loop response. This is crucial for test equipment that must simulate dynamic flight profiles or respond quickly to eVTOL system transients during ground tests, ensuring stable and accurate power delivery.
Thermal Management in Compact GSE: Despite its high current capability, the efficient SJ design helps contain power dissipation. When mounted on a forced-air or liquid-cooled heatsink, it supports the high power density required for trailer-mounted or containerized test stations.
3. VBL2603 (P-MOS, -60V, -130A, TO-263, Trench)
Role: High-current load switch or bus selector for battery pack emulation, high-power auxiliary load control, or output disconnect in the GPU.
Precision Power & Safety Management:
Ultra-High Current Switching in Minimal Space: With an ultra-low Rds(on) of 3mΩ and a massive -130A continuous current rating, this P-channel MOSFET in a TO-263 package is a cornerstone for managing very high current paths (e.g., 48V or 60V battery bus side) with minimal voltage drop and loss. It eliminates the need for a gate driver in high-side switch configurations, simplifying control.
Intelligent Power Routing for Test Flexibility: It can be used to intelligently connect or disconnect large backup battery packs, heavy-duty cooling systems, or dummy loads in a test setup. Its low on-resistance ensures that the switch itself does not become a bottleneck or a significant heat source during high-current operations.
Ruggedness for Field Deployment: The trench technology and robust package offer good reliability against thermal cycling and vibration, which is paramount for GSE that is frequently transported and deployed at temporary test sites.
System-Level Design and Application Recommendations
Drive Circuit Design Key Points:
High-Voltage Switches (VBP17R15S / VBP16R87SFD): Require dedicated gate drivers with adequate current capability. Active Miller clamping is recommended to prevent spurious turn-on in bridge topologies. Attention to high-side isolation is necessary for certain topologies.
High-Current P-MOS Switch (VBL2603): Can often be driven directly by an MCU via a simple level-shifter or bipolar transistor stage due to its P-channel nature. Ensure the gate control circuit can handle the larger gate capacitance for fast switching if needed.
Thermal Management and EMC Design:
Tiered Cooling Strategy: The TO-247 devices (VBP17R15S, VBP16R87SFD) require dedicated heatsinks, potentially forced-air cooled. The VBL2603 must be mounted on a substantial thermal pad connected to a cold plate or large PCB copper plane to manage its high-current heat dissipation.
Noise Suppression: Employ snubber networks across the high-voltage switches to dampen voltage ringing. Use low-ESR capacitors very close to the drain and source of the VBL2603 to decouple high-current pulses. Maintain a compact, low-inductance power loop layout for all high-current paths.
Reliability Enhancement Measures:
Adequate Derating: Operate the 700V/600V MOSFETs at ≤80% of their rated voltage in steady state. Monitor the case temperature of the VBL2603 closely, ensuring it has margin from its maximum rating during sustained high-current operation.
Protection Circuits: Implement desaturation detection for the high-voltage switches. For the VBL2603 branch, use a high-precision current shunt and comparator for fast overcurrent trip. Integrate TVS diodes on gate pins and at the input/output ports for surge immunity.
Environmental Sealing & Conformal Coating: Given the outdoor test environment, the entire power assembly should be designed with appropriate ingress protection (IP rating) and PCB conformal coating to withstand humidity, dust, and temperature swings.
Conclusion
For the design of high-performance, mobile power systems supporting low-altitude eVTOL navigation tests, the strategic selection of power MOSFETs is key to achieving reliability, efficiency, and operational flexibility. The three-tier MOSFET scheme recommended here embodies the design principles of high efficiency, high power density, and field ruggedness.
Core value is reflected in:
End-to-End Test Power Efficiency: From efficient AC-DC front-end conversion (VBP17R15S), through high-fidelity, low-loss power delivery and conditioning (VBP16R87SFD), to the robust and intelligent routing of high currents to the test article (VBL2603), this solution creates a complete, efficient power path from the grid/generator to the eVTOL systems under test.
Test Flexibility & Operational Safety: The use of a high-current P-MOS (VBL2603) allows for safe and simple control of major power branches, enabling flexible configuration of test setups (e.g., battery emulation, load banking) and providing a hardware basis for rapid fault isolation.
Mobile Deployment Robustness: The chosen devices, with their blend of SJ efficiency, low on-resistance, and robust packages, coupled with a system-level focus on thermal management and protection, ensure that the GSE can withstand the rigors of transportation and operation in non-laboratory field conditions.
Future Trends:
As eVTOL power systems evolve towards higher voltages (>800V) and test requirements become more stringent, power device selection for GSE will trend towards:
Adoption of SiC MOSFETs in the primary conversion stages for even higher efficiency and frequency, reducing the size and weight of magnetics and filters in mobile units.
Use of digitally monitored power stages or intelligent switches with integrated sensing for enhanced data logging and predictive health monitoring of the test equipment itself.
Exploration of GaN devices in auxiliary power modules or specific high-frequency circuits to push the power density of mobile support units to new extremes.
This recommended scheme provides a robust power device foundation for eVTOL ground support equipment, enabling reliable and efficient power delivery crucial for successful low-altitude navigation and certification testing. Engineers can adapt and scale this approach based on specific power levels, mobility requirements, and the advanced testing needs of next-generation aerial vehicles.

Detailed Topology Diagrams