With the advancement of urban air mobility (UAM) concepts, high-end modular eVTOL systems, comprising a mothership and detachable aircraft, have emerged as a transformative solution. The powertrain and electrical power distribution system, serving as the "heart and arteries" of the entire vehicle, provide efficient and reliable power conversion and control for critical loads such as propulsion motors, high-voltage battery management, and avionics. The selection of power semiconductors (MOSFETs/IGBTs) directly determines system efficiency, power-to-weight ratio, thermal management, and mission-critical reliability. Addressing the stringent requirements of eVTOL for safety, endurance, high power density, and operational robustness, this article develops a practical and optimized selection strategy based on scenario-specific adaptation.
I. Core Selection Principles and Scenario Adaptation Logic
(A) Core Selection Principles: Three-Dimensional Collaborative Adaptation
Semiconductor selection requires coordinated adaptation across three key dimensions—Voltage/Power Rating, Loss & Power Density, and Extreme Reliability—ensuring precise matching with the harsh operational envelope of aviation:
Sufficient Voltage/Power Margin with High Ruggedness: For high-voltage DC buses (e.g., 800V in the mothership, 400V in the aircraft), select devices with voltage ratings exceeding the maximum bus voltage by 50-100% to withstand regenerative spikes and transients. High current capability and avalanche ruggedness are mandatory.
Ultra-Low Loss for Maximum Power Density: Prioritize devices with minimal Rds(on)/Vce(sat) (conduction loss) and optimized switching figures of merit (Qg, Coss, Eon/Eoff). This is paramount for extending flight endurance, reducing thermal load, and minimizing cooling system weight and volume.
Extreme Reliability and Functional Safety: Devices must operate reliably across a wide temperature range (-55°C to 175°C+), exhibit high thermal stability, and support implementation of redundancy and isolation per aviation safety standards (e.g., DO-254/178).
(B) Scenario Adaptation Logic: Categorization by Vehicle System Function
Divide applications into three core, safety-critical scenarios: First, Mothership High-Voltage Power Distribution & Conversion, requiring high-voltage blocking and efficient power handling. Second, Aircraft Propulsion Motor Inverter, demanding ultra-low loss, high current, and fast switching for high-power motor drives. Third, Critical Avionics & Safety Load Management, requiring compact, isolated switching for reliable control of essential systems.
II. Detailed Semiconductor Selection Scheme by Scenario
(A) Scenario 1: Mothership High-Voltage Power Distribution & Conversion – Power Hub Device
The mothership's power system manages grid charging, battery stacking, and DC-DC conversion for aircraft charging, dealing with voltages up to 800V+.
Recommended Model: VBP17R20SE (N-MOS, 700V, 20A, TO247)
Parameter Advantages: Super-Junction Deep-Trench technology provides a high 700V drain-source voltage, ideal for 400-800V bus applications. An Rds(on) of 165mΩ at 10V balances efficiency and cost. The TO247 package facilitates robust thermal interface mounting.
Adaptation Value: Enables efficient high-voltage switching in PFC stages, isolated DC-DC converters, and solid-state power distribution units (SSPDs). Its high voltage rating ensures reliable operation during network transients, forming a stable power backbone.
Selection Notes: Verify worst-case voltage spikes and derate current appropriately (~50% at high ambient temperature). Must be driven by isolated gate drivers (e.g., with ≥2.5A peak current). Implement comprehensive snubber circuits and overvoltage protection.
(B) Scenario 2: Aircraft Propulsion Motor Inverter – Powertrain Core Device
The aircraft's multi-motor propulsion system requires inverters with the lowest possible conduction and switching losses to maximize thrust-to-power ratio and range.
Recommended Model: VBGP1201N (N-MOS, 200V, 120A, TO247)
Parameter Advantages: SGT technology achieves an exceptionally low Rds(on) of 8.5mΩ at 10V. Continuous current of 120A (with high peak capability) suits high-power multi-phase motor drives. The 200V rating is optimal for 48V or higher voltage aircraft bus architectures.
Adaptation Value: Dramatically reduces inverter conduction losses. For a 100kW motor phase, conduction loss per device is minimized, pushing inverter efficiency above 99%. Supports high switching frequencies (20-50kHz) for optimal motor control and reduced acoustic noise.
Selection Notes: Requires matched high-current gate drivers (e.g., >5A peak). PCB design must minimize power loop inductance using multilayer busbars. Intensive cooling (liquid or forced air) is essential. Implement desaturation detection and short-circuit protection.
(C) Scenario 3: Critical Avionics & Safety Load Management – Safety-Critical Device
This involves switching for essential low-to-medium power loads: flight control computers, sensors, communication gear, and safety isolation relays, where reliability and space savings are critical.
Recommended Model: VBA4311 (Dual P+P MOS, -30V, -12A per channel, SOP8)
Parameter Advantages: The SOP8 package integrates two P-MOSFETs, saving over 60% PCB area compared to discrete solutions—crucial for compact avionics bays. Low Rds(on) of 11mΩ at 10V minimizes voltage drop. The dual independent channels enable redundant or isolated control paths.
Adaptation Value: Enables intelligent, fault-tolerant power distribution to vital loads. Allows for quick isolation of faulty subsystems. The compact form factor supports high-density avionics integration without compromising reliability.
Selection Notes: Ensure gate drive is properly leveled (using NPN buffers or dedicated drivers). Incorporate individual current sensing and fusing per channel. Utilize the dual channels for redundancy (e.g., OR-ing configurations) where required by safety analyses.
III. System-Level Design Implementation Points
(A) Drive Circuit Design: Matching Device Characteristics
VBP17R20SE: Must use reinforced isolated gate drivers (e.g., Silicon Labs Si8239) with sufficient negative bias for noise immunity. Include Miller clamp circuits to prevent parasitic turn-on.
VBGP1201N: Pair with low-impedance, high-speed motor gate driver ICs (e.g., TI UCC5350) capable of high peak currents. Optimize gate drive resistance to balance switching loss and overshoot.
VBA4311: Can be driven directly by microcontroller GPIOs via small-signal transistors for level shifting. Include 10-100Ω gate resistors and RC filters to suppress noise in the electrically noisy aviation environment.
(B) Thermal Management Design: Mission-Critical Heat Dissipation
VBGP1201N & VBP17R20SE: These are the primary heat sources. Mount on dedicated liquid-cooled cold plates or heatsinks with forced air from propulsion ducting. Use thermal interface materials with high conductivity and reliability. Extensive thermal vias and thick copper (≥4oz) on PCB are mandatory.
VBA4311: For moderate loads, a well-designed PCB copper pour (≥150mm² per channel) is sufficient. In high ambient temperature zones, consider connecting the SOP8 tab to a ground plane with thermal vias.
System-Level: Thermal design must account for varying flight profiles (takeoff, cruise, hover) and environmental conditions. Implement predictive thermal monitoring and derating in software.
(C) EMC and Reliability Assurance for Aviation
EMC Suppression:
VBGP1201N: Use low-inductance DC-link capacitors. Implement RC snubbers across each switch and common-mode chokes on motor output lines.
VBP17R20SE: Employ SiC or fast-recovery diodes in associated circuits. Use ferrite beads on gate drive supply lines.
System: Enforce strict zoning between high-power, high-speed, and sensitive analog/digital sections. Use shielded cables for critical connections.
Reliability & Protection:
Derating: Apply stringent derating rules (e.g., voltage ≤70%, current ≤50-60% at max junction temperature).
Fault Protection: Implement hardware-based overcurrent (desat protection for IGBTs/MOSFETs), overtemperature, and overvoltage protection on all power stages. Cross-channel monitoring for dual-switch configurations like VBA4311.
Transient Protection: Utilize TVS diodes at all external interfaces and power inputs. Protect gate pins with series resistors and bidirectional TVS.
IV. Scheme Core Value and Optimization Suggestions
(A) Core Value
Enhanced Safety & Redundancy: The selected devices enable architectures with inherent redundancy (dual channels) and robust protection, directly supporting compliance with aviation functional safety goals.
Maximized Endurance & Performance: Ultra-low loss devices in the propulsion chain translate directly into extended flight time or increased payload capacity.
Optimized Weight & Volume: The combination of high-efficiency devices (reducing heatsink mass) and highly integrated packages (like SOP8 dual MOSFETs) contributes significantly to a superior power-to-weight ratio.
(B) Optimization Suggestions
For Higher Voltage/Performance: In next-generation 1000V+ systems, consider transitioning to SiC MOSFETs (e.g., 1200V rated) for the mothership's primary converters to further reduce loss and size.
For Higher Integration: For propulsion inverters, evaluate power modules (IPMs) that integrate multiple VBGP1201N-type dies with drivers and protection for reduced parasitic inductance and improved reliability.
For Extreme Environments: Specify extended temperature and high-reliability screening grades (e.g., space-grade or automotive AEC-Q101 Grade 0) for all components in safety-critical paths.
Intelligent Power Management: Pair the VBA4311 in load management with smart high-side switch ICs featuring integrated diagnostics (current, temperature, status feedback) for enhanced health monitoring.
Conclusion
The strategic selection of power semiconductors is fundamental to achieving the safety, endurance, performance, and reliability required by modular eVTOL systems. This scenario-based scheme, from high-voltage power distribution to precision load management, provides comprehensive technical guidance for aerospace-grade electrical system design. Future development will focus on the adoption of Wide Bandgap (WBG) devices and highly integrated Intelligent Power Modules (IPMs), paving the way for the next generation of efficient, compact, and certifiable urban air vehicles.

Detailed Scenario Topology Diagrams