With the rapid development of urban air mobility and emergency response demands, high-end firefighting eVTOLs (Electric Vertical Take-Off and Landing aircraft) have become critical assets for rapid urban firefighting and rescue. Their powertrain and auxiliary system drive, serving as the "core propulsion and power backbone," must deliver robust, efficient, and fault-tolerant power conversion for critical loads such as lift/cruise motors, firefighting pumps, lighting systems, and avionics. The selection of power semiconductors (MOSFETs/IGBTs) directly determines the system's power density, operational efficiency, electromagnetic compatibility (EMC), and mission reliability. Addressing the stringent requirements of firefighting eVTOLs for high power, safety, redundancy, and environmental resilience, this article centers on scenario-based adaptation to reconstruct the selection logic, providing an optimized solution ready for direct implementation.
I. Core Selection Principles and Scenario Adaptation Logic
Core Selection Principles
High Voltage and Current Ruggedness: For high-voltage bus systems (typically 400V-800V), devices must have sufficient voltage margins (≥30-50% above bus) and current ratings to handle startup surges, regenerative braking, and fault conditions.
Ultra-Low Loss for Extended Range: Prioritize devices with low conduction losses (low Rds(on) or VCEsat) and optimized switching characteristics to maximize efficiency, reduce thermal stress, and extend flight time/range.
Robust Package and Thermal Performance: Select packages like TO247, TO220F, TO252 that offer excellent thermal conductivity and mechanical strength to withstand vibration, high ambient temperatures, and enable effective heat sinking.
Military-Grade Reliability and Redundancy: Designed for mission-critical operation, devices must exhibit high thermal stability, avalanche ruggedness, and support system-level redundancy and fault isolation.
Scenario Adaptation Logic
Based on the core operational profiles of a firefighting eVTOL, semiconductor applications are divided into three primary scenarios: Main Propulsion Motor Drive (Power Core), High-Current Power Distribution & Switching (Energy Management), and Auxiliary & Firefighting System Control (Mission-Critical). Device parameters and characteristics are matched accordingly.
II. Semiconductor Selection Solutions by Scenario
Scenario 1: Main Propulsion Motor Drive (50kW-200kW per motor) – Power Core Device
Recommended Model: VBP165R25SE (Single-N MOSFET, 650V, 25A, TO247)
Key Parameter Advantages: Utilizes SJ_Deep-Trench technology, offering a balance of high voltage blocking (650V) and low on-resistance (115mΩ @10V). Avalanche rated and capable of continuous 25A current, suitable for high-voltage motor inverter bridges.
Scenario Adaptation Value: The robust TO247 package ensures low thermal resistance and high power cycling capability, essential for the demanding thermal environment near motors. Low conduction loss minimizes heat generation in the inverter, contributing to higher overall powertrain efficiency. Its high voltage rating provides safety margin for 400V-600V bus systems common in eVTOLs.
Applicable Scenarios: High-voltage three-phase inverter bridge for lift and cruise BLDC/PMSM motors, supporting precise vector control and regenerative braking.
Scenario 2: High-Current Power Distribution & Switching – Energy Management Device
Recommended Model: VBMB2611 (Single-P MOSFET, -60V, -60A, TO220F)
Key Parameter Advantages: Features ultra-low Rds(on) of 12mΩ @10V, enabling minimal conduction loss at high currents up to -60A. The -60V rating is suitable for auxiliary 48V/60V power networks.
Scenario Adaptation Value: The TO220F (fully isolated) package simplifies heatsink mounting and provides electrical isolation. Its exceptionally low on-resistance makes it ideal for main battery disconnect switches, pre-charge circuits, and high-current DC bus distribution. This minimizes voltage drop and power loss in critical power paths, enhancing overall system efficiency and thermal management.
Applicable Scenarios: Main battery contactor replacement, solid-state circuit breakers, high-current load switching for auxiliary generators or pump motors.
Scenario 3: Auxiliary & Firefighting System Control – Mission-Critical Device
Recommended Model: VBE1695 (Single-N MOSFET, 60V, 18A, TO252)
Key Parameter Advantages: Offers a good balance of voltage rating (60V) and current capability (18A) with Rds(on) of 73mΩ @10V. Gate threshold voltage of 1.7V allows compatibility with 3.3V/5V logic.
Scenario Adaptation Value: The compact TO252 (DPAK) package provides good power handling in a small footprint, suitable for distributed control modules. Its robust current rating supports direct drive of significant auxiliary loads like servo actuators for firefighting nozzles, high-intensity searchlights, or cooling fans. Ensures reliable switching for mission-critical functions that must operate flawlessly during firefighting operations.
Applicable Scenarios: Solenoid/valve control for firefighting systems, LED lighting array drivers, auxiliary pump or fan motor drives, and avionics power switching.
III. System-Level Design Implementation Points
Drive Circuit Design
VBP165R25SE: Requires a dedicated high-side/low-side gate driver IC with sufficient peak current capability (e.g., 2A-4A). Careful attention to minimizing gate loop inductance is critical for clean switching.
VBMB2611: As a high-side P-MOSFET, requires a level-shifted gate drive. Can be driven by a simple NPN transistor or a dedicated high-side driver. Incorporate a gate pull-down resistor for definite turn-off.
VBE1695: Can be driven directly by microcontroller GPIOs for lower frequency switching. For higher frequencies or inductive loads, use a gate driver buffer. Always include series gate resistors to damp ringing.
Thermal Management Design
Hierarchical Thermal Strategy: VBP165R25SE must be mounted on a large heatsink, potentially liquid-cooled in high-power designs. VBMB2611 requires a substantial heatsink connected via the TO220F tab. VBE1695 can often be cooled via a PCB copper pour area or a small clip-on heatsink.
Derating for Altitude and Temperature: Design for junction temperature below 125°C at maximum ambient (e.g., 70°C+). Apply significant derating (e.g., 50-60% of rated current) for continuous operation at high altitudes where cooling is less efficient.
EMC and Reliability Assurance
EMI Suppression: Use RC snubbers across drain-source of VBP165R25SE in the inverter bridge. Implement proper filtering at the input of VBMB2611 switching nodes. For inductive loads driven by VBE1695, use flyback diodes or TVS protection.
Protection Measures: Implement desaturation detection for VBP165R25SE. Use current sense resistors and fast-acting fuses in series with VBMB2611. For all gates, incorporate TVS diodes for ESD/surge protection and ensure robust ground referencing to avoid latch-up.
IV. Core Value of the Solution and Optimization Suggestions
The power semiconductor selection solution for high-end urban firefighting eVTOLs proposed in this article, based on scenario adaptation logic, achieves comprehensive coverage from core propulsion to power distribution and mission-specific auxiliary control. Its core value is mainly reflected in the following three aspects:
Maximized Power Density and Efficiency: By selecting optimized devices for each high-power segment—from the 650V motor drive to the ultra-low Rds(on) power switch—system-level losses are minimized. This translates to higher efficiency powertrains, reduced thermal management burden, and extended operational range or loiter time, which is critical for firefighting missions.
Enhanced Mission Reliability and Safety: The use of rugged, high-voltage devices for propulsion ensures tolerance to voltage spikes. The isolated package of VBMB2611 enhances safety in high-current distribution. The robust control capability of VBE1695 guarantees reliable operation of firefighting equipment under vibration and thermal stress. This layered approach builds inherent redundancy and fault tolerance into the power system.
Optimal Balance of Performance and Aerospace-Grade Robustness: The selected devices offer proven reliability, necessary electrical margins, and packages suited for harsh environments. Compared to unproven or exotic technologies, this solution provides a cost-effective, supply-chain-stable path to meeting the demanding requirements of aviation and emergency response applications without compromising on performance.
In the design of power systems for high-end urban firefighting eVTOLs, semiconductor selection is a cornerstone for achieving the trifecta of high power, unwavering reliability, and mission adaptability. The scenario-based selection solution proposed here, by aligning device characteristics with specific operational demands and integrating robust system-level design practices, delivers a comprehensive, actionable technical framework. As eVTOLs evolve towards higher voltages, greater intelligence, and more complex mission profiles, future exploration should focus on the integration of SiC MOSFETs for even higher efficiency and the development of smart power modules with embedded health monitoring, paving the way for the next generation of life-saving aerial firefighting platforms.

Detailed System Topology Diagrams