With the rapid development of unmanned aerial systems for critical infrastructure monitoring, Electric Vertical Take-Off and Landing (eVTOL) aircraft for oil and gas pipeline inspection demand extremely high reliability, efficiency, and robustness from their powertrain and avionics systems. The power MOSFETs, serving as the core switches for the propulsion motor drives, high-voltage DC-DC conversion, and distributed load management, directly determine the system's performance, flight endurance, and operational safety in harsh environments. Addressing the stringent requirements for high voltage, high power density, thermal resilience, and electromagnetic compatibility (EMC) in aerospace applications, this article reconstructs the MOSFET selection logic based on mission-critical scenarios, providing an optimized, ready-to-implement solution.
I. Core Selection Principles and Scenario Adaptation Logic
Core Selection Principles
1. High Voltage & Safety Margin: For high-voltage propulsion bus (typically 540V-800V DC), MOSFET voltage rating must withstand transients and ringing with a safety margin ≥20-30%. For lower-voltage avionics buses (28V/48V), a ≥50% margin is essential.
2. Loss Minimization for Endurance: Prioritize low Rds(on) and optimized gate charge (Qg) to minimize conduction and switching losses, directly extending flight time.
3. Package for Power Density & Cooling: Select packages (TO247, TO220, TO252, SOP8) based on power level and thermal management strategy (heatsink, forced air), balancing current capability with space constraints.
4. Ultra-High Reliability & Ruggedness: Devices must operate flawlessly under wide temperature ranges, vibration, and potential contamination. Focus on avalanche energy rating, SOA, and stable Vth over temperature.
Scenario Adaptation Logic
Based on the eVTOL's power architecture, MOSFET applications are divided into three primary scenarios: Main Propulsion Inverter (High-Power Core), Auxiliary Power Unit (APU) & DC-DC Conversion (Medium-Power Support), and Distributed Critical Load Switching (Low-Voltage Management). Device parameters are matched to the specific voltage, current, and control needs of each scenario.
II. MOSFET Selection Solutions by Scenario
Scenario 1: Main Propulsion Inverter (20-50kW per motor) – High-Power Core Device
Recommended Model: VBP18R20S (Single N-MOS, 800V, 20A, TO247)
Key Parameter Advantages: High voltage rating of 800V is ideal for 540V-700V propulsion bus applications. Utilizing SJ_Multi-EPI technology, it offers a competitive Rds(on) of 220mΩ at 10V Vgs, balancing conduction loss and cost for this voltage class. The 20A continuous current rating supports phase currents in multi-kW motor drives.
Scenario Adaptation Value: The robust TO247 package facilitates excellent thermal coupling to external heatsinks, critical for managing high inverter losses. Its high voltage rating provides necessary margin against bus spikes, enhancing system reliability for continuous high-power flight operations.
Applicable Scenarios: High-voltage multi-phase inverter bridge for brushless DC (BLDC) or Permanent Magnet Synchronous Motor (PMSM) propulsion drives.
Scenario 2: Auxiliary Power Unit (APU) & High-Voltage DC-DC Conversion (1-3kW) – Medium-Power Support Device
Recommended Model: VBE165R08SE (Single N-MOS, 650V, 8A, TO252)
Key Parameter Advantages: 650V rating is suitable for off-the-shelf 400V-500V APU generator rectification or step-down DC-DC converters. SJ_Deep-Trench technology provides a good efficiency balance with 460mΩ Rds(on). The 8A rating fits medium-power conversion stages.
Scenario Adaptation Value: The compact TO252 (D-PAK) package offers a good trade-off between power handling and board space, suitable for densely packed auxiliary power modules. Its voltage and current ratings are well-matched for secondary power conversion and control within the inspection payload and avionics power supply.
Applicable Scenarios: Primary-side switches in isolated DC-DC converters, synchronous rectification in APU output stages, and power switching for medium-power auxiliary systems.
Scenario 3: Distributed Critical Load Switching (Avionics, Sensors, Actuators) – Low-Voltage Management Device
Recommended Model: VBA3615 (Dual N-MOS, 60V, 10A per Ch, SOP8)
Key Parameter Advantages: Dual N-channel configuration in a compact SOP8 package enables high-density board design. Very low Rds(on) of 12mΩ (at 10V) minimizes voltage drop and loss. 60V rating is perfect for 28V avionics bus with ample margin. Low Vth of 1.7V allows direct drive from 3.3V/5V flight controller GPIO.
Scenario Adaptation Value: The dual independent MOSFETs allow intelligent and isolated control of two critical loads (e.g., a sensor suite and a communication module). Ultra-low conduction loss is crucial for always-on subsystems to conserve energy. The small footprint supports distributed power management near loads.
Applicable Scenarios: Individual enable/disable control for inspection payloads (laser scanners, gas sensors), avionics module power sequencing, and actuator (e.g., gimbal) drive circuit switching.
III. System-Level Design Implementation Points
Drive Circuit Design
VBP18R20S: Must be paired with high-current, isolated gate driver ICs. Careful PCB layout to minimize high-voltage loop inductance is critical. Use gate resistors to control switching speed and damp oscillations.
VBE165R08SE: Can be driven by standard gate driver ICs. Ensure sufficient drive current for fast switching in DC-DC topologies.
VBA3615: Can be driven directly by MCU pins for low-frequency switching. For higher frequencies, use a small driver buffer. Include gate-source resistors for stability.
Thermal Management Design
Hierarchical Strategy: VBP18R20S requires dedicated heatsinks with forced air or liquid cooling. VBE165R08SE benefits from PCB copper pours and possibly a small heatsink. VBA3615 typically dissipates heat through its package and PCB copper.
Derating Practice: Operate at ≤70-80% of rated current in continuous mode. Design thermal interface to keep junction temperature at least 15-20°C below maximum rating at highest ambient temperature (e.g., 70°C+).
EMC and Reliability Assurance
EMI Suppression: Use snubber circuits across drain-source of high-voltage MOSFETs (VBP18R20S, VBE165R08SE). Ensure low-inductance power bus layout. Employ ferrite beads on gate drive paths if needed.
Protection Measures: Implement comprehensive overcurrent and overtemperature protection at the system level. Use TVS diodes on all gate pins and at the input of avionics buses for surge/ESD protection. Ensure fault isolation between critical subsystems controlled by devices like VBA3615.
IV. Core Value of the Solution and Optimization Suggestions
The power MOSFET selection solution for pipeline inspection eVTOLs, based on scenario adaptation, provides complete coverage from megawatt-level propulsion to watt-level sensor control. Its core value is threefold:
1. Maximized Flight Endurance through Chain Efficiency: By selecting optimized devices for each power chain segment—from the high-voltage propulsion inverter (VBP18R20S) to the auxiliary converter (VBE165R08SE) and down to the load switch (VBA3615)—losses are minimized at every stage. This holistic approach reduces total energy waste, directly translating into longer flight times or the ability to carry heavier inspection payloads, a critical competitive advantage.
2. Enhanced Mission Reliability and Safety: The use of high-voltage-rated, rugged devices (SJ technology) in the powertrain ensures resilience against electrical stress. The independent dual-channel control offered by devices like VBA3615 allows for robust fault containment and graceful degradation of non-propulsion systems, ensuring the eVTOL can safely abort or complete its mission even if a non-critical payload fails.
3. Optimal Balance of Performance, Density, and Cost: This solution leverages mature, high-reliability package technologies (TO247, TO252, SOP8) and proven silicon processes (SJ, Trench). It avoids the premature adoption of exotic, expensive wide-bandgap devices where they are not yet cost-justified, instead delivering superior performance and reliability within a practical budget, accelerating time-to-market for inspection eVTOL platforms.
In the design of power systems for oil and gas pipeline inspection eVTOLs, strategic MOSFET selection is paramount for achieving the trifecta of endurance, reliability, and safety. This scenario-based solution, by precisely matching device characteristics to specific load requirements and coupling it with rigorous system-level design practices, provides a clear and actionable technical roadmap. As eVTOLs evolve towards higher voltages, greater intelligence, and more autonomous operations, future exploration should focus on the integration of silicon carbide (SiC) MOSFETs for the main inverter to push efficiency boundaries further, and the adoption of intelligent power modules that integrate sensing and protection, laying a robust hardware foundation for the next generation of ultra-reliable, long-endurance industrial inspection drones.

Detailed Topology Diagrams