Preface: Forging the "Power Heart" of Aerial Industrial Logistics – The Systems Engineering Behind Aerial Vehicle Power Device Selection
In the emerging frontier of AI-automated, low-altitude material transport within mining operations, the eVTOL (Electric Vertical Take-Off and Landing) aircraft is not merely a flying platform but a highly integrated, intelligent energy system. Its core performance—payload capacity, mission endurance, operational safety, and dispatch reliability—is fundamentally anchored in the efficiency, power density, and robustness of its electrical powertrain. This article adopts a mission-profile-driven, systems-engineering approach to deconstruct the critical challenges within an eVTOL's power chain: how to select the optimal power semiconductor combination for the high-power propulsion inverter, the high-reliability avionics DC-DC converter, and the fault-tolerant auxiliary load management system, under the extreme constraints of unparalleled reliability, severe weight/volume limits, and demanding thermal environments.
Based on comprehensive analysis of peak/continuous power demands, fault containment strategies, and thermal management in confined airborne spaces, this article selects three pivotal devices to construct a hierarchical, mission-optimized power solution.
I. In-Depth Analysis of the Selected Device Combination and Application Roles
1. The Muscle of Ascent: VBM1104S (100V, 180A, TO-220) – Main Propulsion Inverter Phase-Leg Switch
Core Positioning & Topology Deep Dive: This device is the workhorse of the multi-phase motor drive inverter for lift and cruise propulsors. Its exceptionally low `Rds(on)` of 3.6mΩ @10V is critical for minimizing conduction loss, which is the dominant loss component in high-torque, low-speed maneuvers like hover and heavy lift. The 100V rating is optimally suited for high-current segments of advanced high-voltage battery arrays (e.g., 400V or 800V systems using multi-level topologies).
Key Technical Parameter Analysis:
Ultra-Low Conduction Loss: The minuscule Rds(on) directly translates to maximum efficiency during high-current draw, extending battery life and reducing thermal load. This is paramount for climb performance and payload maximization.
High Current Capability: The 180A continuous rating ensures robust handling of peak phase currents during aggressive climb-outs or gust recoveries, with substantial margin.
Technology & Drive: The Trench technology offers a favorable balance of low on-resistance and gate charge. Careful gate driver design is essential to leverage its fast switching capability, minimizing switching losses at high PWM frequencies required for smooth FOC (Field-Oriented Control) of BLDC/PMSM motors.
2. The Avionics Power Sanctum: VBPB17R20S (700V, 20A, TO-3P) – Isolated High-Voltage to Low-Voltage DC-DC Primary Side Switch
Core Positioning & System Benefit: This Super Junction MOSFET is engineered for the primary side of an isolated DC-DC converter (e.g., LLC Resonant or Phase-Shifted Full-Bridge) that steps down the high-voltage traction bus (e.g., 600V+) to a stable 28V or 48V avionics bus. The 700V drain-source voltage provides critical margin against voltage spikes from transformer leakage inductance.
Key Technical Parameter Analysis:
Voltage Ruggedness: The 700V rating is essential for reliable operation directly off the high-voltage bus, accommodating transients and ensuring long-term reliability in the harsh EMI environment of an eVTOL.
Efficiency in Soft-Switching Topologies: The SJ_Multi-EPI technology, combined with the TO-3P package's superior thermal performance, makes it ideal for soft-switching topologies. These topologies minimize switching losses, enabling high-frequency operation, which reduces the size and weight of the isolation transformer and output filter—a critical advantage for aerospace applications.
System Reliability: A stable, clean avionics bus is non-negotiable for flight control computers, sensors, and communications. This device forms the foundation of that ultra-reliable power supply.
3. The Intelligent Load Steward: VBFB2309 (-30V, -70A, TO-251) – High-Current Auxiliary Load Distribution & Ideal Diode Controller
Core Positioning & System Integration Advantage: This P-Channel MOSFET is the key to intelligent and robust management of high-current auxiliary systems like electromechanical actuators for flight controls, winches, payload interfaces, or heating systems.
Key Technical Parameter Analysis:
High-Current, Low-Loss Switching: With an `Rds(on)` as low as 8mΩ @10V and a -70A current rating, it introduces negligible voltage drop in high-power auxiliary paths, preserving efficiency.
P-Channel for Simplified High-Side Control: Its logic-level compatible gate (fully enhanced at -4.5V or -10V) allows direct control from microcontrollers or PMUs without charge pumps, simplifying driver circuits and enhancing reliability for critical load shed functions.
Application Versatility: It can be configured as a smart load switch with inrush current control and fast fault disconnect, or as part of an "ideal diode" circuit for OR-ing redundant power supplies or implementing redundant battery bus architectures, a common requirement for aircraft safety.
II. System Integration Design and Expanded Key Considerations
1. Topology, Drive, and Control Loop
Propulsion Inverter & Motor Control: The VBM1104S switches must be driven by high-performance, isolated gate drivers synchronized precisely with the motor controller's FOC algorithm. Low-inductance power loops and careful attention to `dV/dt` and `di/dt` are critical to minimize EMI and voltage overshoot.
Avionics DC-DC & Redundancy: The VBPB17R20S within the DC-DC converter requires a controller capable of implementing advanced soft-switching protocols. The entire converter module should ideally be duplicated (N+1 redundancy) for the avionics bus, with the outputs OR'd using circuits employing devices like the VBFB2309.
Digital Load Management: Each VBFB2309 should be under the command of a dedicated Power Management Unit (PMU) or the Vehicle Management Computer (VMC), enabling programmable soft-start, sequential power-up, real-time current monitoring, and millisecond-level fault isolation.
2. Hierarchical Thermal Management Strategy
Primary Heat Source (Liquid Cooling Plate): The VBM1104S devices in the propulsion inverter will be the largest heat source. They must be mounted on a direct-cooled liquid cold plate integrated into the aircraft's liquid cooling loop.
Secondary Heat Source (Forced Air Cooling): The VBPB17R20S and its DC-DC converter module require dedicated forced air cooling via a blower, given its placement likely away from the central liquid cooling system but within an avionics bay.
Tertiary Heat Source (Conduction to Chassis): The VBFB2309, used in distributed load centers, should be mounted on PCB areas with thick copper pours and thermal vias, conducting heat to the local airframe structure or a secondary heatsink.
3. Engineering Details for Reliability Reinforcement
Electrical Stress Protection:
Propulsion Inverter: Utilize RC snubbers across each VBM1104S or bus capacitors to manage ringing from motor cable inductance.
DC-DC Converter: Careful snubber design (RCD or resonant) is needed for the VBPB17R20S to clamp voltages from transformer leakage inductance.
Auxiliary Loads: Freewheeling diodes or TVS must be provided for inductive loads (actuators, solenoids) switched by the VBFB2309.
Enhanced Gate Protection: All gate drives must be fortified with series resistors, low-ESR decoupling capacitors, and bidirectional TVS or Zener diodes (e.g., ±15V to ±20V) for gate-source clamping. Redundant pull-down resistors ensure fail-off states.
Aerospace-Grade Derating Practice:
Voltage Derating: Apply at least 60-70% derating on voltage ratings. For VBPB17R20S, the maximum applied DC bus plus spike should be ≤ 450V-500V.
Current & Thermal Derating: All current ratings must be based on worst-case junction temperature `Tj_max` (e.g., 110°C for high reliability). Use transient thermal impedance curves to size devices for short-duration overloads like actuator stall. Significant derating from datasheet `Id` is mandatory.
III. Quantifiable Perspective on Scheme Advantages and Competitor Comparison
Quantifiable Power Density & Efficiency Gain: Using VBM1104S in the propulsion inverter versus standard 100V MOSFETs can reduce conduction losses by over 40% at peak current, directly increasing hover time or allowing for a smaller, lighter battery pack for the same mission.
Quantifiable System Reliability & Safety Improvement: Implementing intelligent load management with VBFB2309 enables rapid isolation of faulted subsystems (e.g., a jammed actuator), preventing single-point failures from cascading. This directly contributes to a higher DAL (Design Assurance Level) for the electrical system.
Lifecycle & Maintenance Optimization: The selected robust components, combined with rigorous protection and derating, lead to a significantly higher MTBF (Mean Time Between Failures) for the power electronics, reducing unscheduled maintenance in remote mining operations and maximizing vehicle availability.
IV. Summary and Forward Look
This scheme delivers a cohesive, optimized power chain for mining eVTOLs, addressing the triumvirate of demands: propulsive power, avionics sanctity, and auxiliary intelligence.
Propulsion Level – Focus on "Power Density & Efficiency": Deploy the lowest possible `Rds(on)` technology to maximize thrust-to-electrical-power ratio.
Power Conversion Level – Focus on "Ultimate Reliability & Isolation": Select high-voltage-rated, thermally robust devices for the mission-critical avionics power supply.
Power Management Level – Focus on "Fault Tolerance & Control": Utilize high-current P-MOSFETs for intelligent, software-defined load management to enhance overall system resilience.
Future Evolution Directions:
Gallium Nitride (GaN) HEMTs for Propulsion: For next-generation eVTOLs, transitioning the propulsion inverter to 100V-150V GaN devices can push switching frequencies into the MHz range, dramatically shrinking motor filter size and weight, and enabling even higher efficiency.
Fully Integrated Smart Power Switches: The auxiliary load management can evolve towards CIPOS (Intelligent Power SOI) or similar modules that integrate the MOSFET, driver, protection, and diagnostic feedback into a single package, further saving space and improving noise immunity.
Wide-Bandgap in DC-DC: The high-voltage DC-DC stage can benefit from SiC MOSFETs for even higher frequency operation and efficiency, further reducing the size and weight of the power conversion system.
Engineers can refine this framework based on specific eVTOL parameters: propulsion motor voltage/peak power, avionics bus architecture (28V/270V), redundancy requirements, and the detailed thermal management budget.

Detailed Topology Diagrams