With the rise of urban air mobility (UAM), short-haul electric vertical take-off and landing (eVTOL) air taxis represent the future of intracity transportation. The performance, safety, and range of these 2-seater aircraft are fundamentally determined by their electrical propulsion and power management systems. High-efficiency motor inverters, battery management units (BMUs), and distributed auxiliary power networks act as the aircraft's "power heart and nervous system," responsible for delivering precise, high-thrust propulsion and ensuring intelligent energy allocation. The selection of power MOSFETs critically impacts system power-to-weight ratio, conversion efficiency, thermal management, and operational reliability. This article, targeting the demanding application scenario of eVTOL air taxis—characterized by extreme requirements for weight savings, dynamic response, safety redundancy, and harsh operational environments—conducts an in-depth analysis of MOSFET selection for key power nodes, providing a complete and optimized device recommendation scheme.
Detailed MOSFET Selection Analysis
1. VBP165C70-4L (N-MOS, 650V, 70A, TO-247-4L, SiC Technology)
Role: Primary switch in the main propulsion inverter or high-voltage bidirectional DC-DC converter (linking battery pack to motor drive bus).
Technical Deep Dive:
Voltage Stress & Efficiency Core: For eVTOLs utilizing high-voltage battery packs (typically 400V-800V DC), the 650V-rated SiC MOSFET provides a robust safety margin against voltage spikes during high-frequency PWM switching in the inverter. Its Silicon Carbide (SiC) technology offers inherently lower switching losses and reverse recovery charge compared to silicon, enabling ultra-high switching frequencies (tens to hundreds of kHz). This directly reduces the size and weight of output filter components and motor chokes, which is paramount for achieving the high power-to-weight ratio essential for flight.
Power Density & Thermal Performance: With an exceptionally low Rds(on) of 30mΩ and a high continuous current rating of 70A, this device minimizes conduction losses in high-power phases. The TO-247-4L (Kelvin source) package improves switching performance by reducing source inductance, allowing for faster switching and reduced voltage overshoot. This contributes to higher inverter efficiency, directly extending aircraft range and reducing thermal management burden—a critical factor in compact, passively or liquid-cooled aviation enclosures.
System Scalability: Its high current handling allows for scalable power design in multi-phase inverter topologies. The SiC nature ensures stable operation at elevated junction temperatures, supporting the demanding thermal cycles of repeated take-off, cruise, and landing profiles.
2. VBGL2403 (P-MOS, -40V, -150A, TO-263, SGT Technology)
Role: Main switch for low-voltage, ultra-high-current battery protection, discharge control, or as a synchronous rectifier in low-voltage, high-power DC-DC stages (e.g., step-down converters for avionics).
Extended Application Analysis:
Ultra-Low Loss Battery Interface: Managing the high discharge currents from the main battery pack to the inverter or other loads requires switches with minimal voltage drop. The VBGL2403, with its -40V rating, is ideal for 24V or 48V auxiliary bus applications, providing ample margin. Its Super Junction Trench (SGT) technology achieves an ultra-low Rds(on) of 2.8mΩ at 10V drive, coupled with a massive -150A continuous current capability. This minimizes conduction losses at the critical battery interface, preserving precious energy for thrust.
Power Density & Thermal Challenge: The TO-263 (D2PAK) package offers an excellent surface area-to-volume ratio for heat dissipation, suitable for direct mounting onto compact, liquid-cooled cold plates or heatsinks integrated into the aircraft's structure. Its high current density supports the trend towards centralized battery protection units without sacrificing efficiency, crucial for maximizing payload capacity.
Dynamic Response: Low gate charge enables fast switching, necessary for implementing advanced protection features like electronic fusing with microsecond-level response, safeguarding the battery and downstream systems during fault conditions.
3. VBA1210 (N-MOS, 20V, 13A, SOP8, Trench Technology)
Role: Intelligent power distribution switch for critical avionics, flight control systems, sensors, and auxiliary loads (e.g., communication modules, lighting, servo actuators).
Precision Power & Safety Management:
High-Density Intelligent Control: This N-channel MOSFET in a compact SOP8 package is perfectly suited for the 12V or lower avionics power rails common in eVTOLs. Its low Rds(on) of 8mΩ at 10V ensures negligible voltage drop even when powering multiple sensitive loads. It enables modular, point-of-load power switching, allowing the flight computer to intelligently enable/disable subsystems based on flight phase, fault conditions, or power-saving modes, thereby enhancing overall system reliability and energy efficiency.
Low-Power Drive & Integration: With a standard logic-level threshold (Vth: 0.5-1.5V), it can be driven directly by microcontrollers or power management ICs without need for level shifters, simplifying control circuitry and saving board space—a premium in airborne electronics. The small footprint allows for dense placement near loads, reducing trace resistance and improving local decoupling.
Environmental Robustness: Trench technology and the SOP8 package provide good mechanical stability against vibration, a critical factor in the dynamic flight environment of an air taxi. Its performance over a wide temperature range ensures reliable operation from ground level to altitude.
System-Level Design and Application Recommendations
Drive Circuit Design Key Points:
High-Side/SiC Switch Drive (VBP165C70-4L): Requires a dedicated, high-speed gate driver capable of delivering high peak currents for fast switching. Careful attention must be paid to the PCB layout to minimize common source inductance (using the 4th pin) and power loop inductance. Active gate driving techniques (like adaptive gate voltage) can be employed to optimize switching losses and EMI.
High-Current P-MOS Drive (VBGL2403): Requires a driver with sufficient current capability to handle the large gate capacitance for fast turn-on/off. For high-side configuration (in battery protection circuits), a bootstrap or isolated gate driver solution is necessary. Parallel gate resistors may be used to fine-tune switching speed and damp oscillations.
Avionics Switch Drive (VBA1210): Simple direct MCU drive is feasible. Incorporating series gate resistors and local TVS diodes is recommended to suppress EMI-induced glitches and provide ESD protection in the electrically noisy aircraft environment.
Thermal Management and EMC Design:
Tiered Thermal Design: The VBP165C70-4L must be mounted on a high-performance, low-thermal-resistance heatsink, likely liquid-cooled. The VBGL2403 requires intimate thermal coupling to a cold plate via thermal interface material. The VBA1210 can dissipate heat effectively through a generous PCB copper pour connected to its drain pad.
EMI Suppression: Utilize snubber networks (RC or RCD) across the drain-source of the SiC MOSFET to damp high-frequency ringing. Place low-inductance, high-frequency decoupling capacitors very close to the drain and source terminals of the VBGL2403. Implement strict partitioning between high-power motor drive loops and sensitive avionics signal planes, using shielding and ferrite beads where necessary.
Reliability Enhancement Measures:
Adequate Derating: Operate the VBP165C70-4L at no more than 70-80% of its rated voltage under worst-case line/load transients. Continuously monitor the junction temperature of the VBGL2403, especially during peak thrust demands (take-off). Ensure the VBA1210 operates well within its SOA for its specific load profile.
Multiple Protections: Implement redundant current sensing and hardware-based overcurrent protection for branches controlled by the VBA1210, with fast shutdown signals to the flight controller. For the main inverter (using VBP165C70-4L), integrate desaturation detection and short-circuit protection at the driver level.
Enhanced Protection: Apply TVS diodes at the gate and drain of all MOSFETs for surge suppression. Maintain aviation-grade creepage and clearance distances on the PCB, conformally coated for protection against condensation and contaminants.
Conclusion
In the design of high-power-density, high-reliability electrical systems for urban short-haul eVTOL air taxis, strategic power MOSFET selection is key to achieving safe, efficient, and long-endurance flight. The three-tier MOSFET scheme recommended in this article embodies the design philosophy of minimizing weight, maximizing efficiency, and enabling intelligent power management.
Core value is reflected in:
Propulsion Efficiency & Weight Reduction: From the high-frequency, low-loss switching in the main propulsion inverter (VBP165C70-4L), to the ultra-efficient, low-voltage drop battery interface (VBGL2403), and down to the precise, low-quiescent power management of avionics (VBA1210), a full-chain optimized power delivery path from battery to thrust is established, directly contributing to extended range and payload capacity.
Intelligent Operation & Safety: The use of distributed, digitally controllable switches like the VBA1210 provides the hardware basis for advanced health monitoring, power sequencing, and fault isolation of non-propulsion systems, enhancing overall aircraft safety and maintainability.
Harsh Environment Adaptability: The selected devices, through a combination of advanced semiconductor technology (SiC, SGT) and robust packaging, coupled with rigorous thermal and protection design, ensure reliable operation under the extreme conditions of vibration, temperature swings, and altitude changes inherent to aviation.
Future-Oriented Scalability: The modular approach and device characteristics allow for straightforward scaling of power stages (e.g., parallelizing SiC MOSFETs for higher power ratings) to adapt to future eVTOL models with increased passenger capacity or performance requirements.
Future Trends:
As eVTOL technology evolves towards higher voltages (>800V), more integrated propulsion units (e.g., motor-in-wheel), and advanced vehicle health management systems, power device selection will trend towards:
Widespread adoption of higher voltage (1200V+) SiC MOSFETs in main inverters for even greater efficiency and power density.
Intelligent power switches with integrated current, voltage, and temperature sensing, communicating via digital interfaces (e.g., PMBus) for predictive maintenance.
Increased use of GaN HEMTs in auxiliary power modules (APUs) and high-frequency DC-DC converters to achieve MHz-range switching and further reduce magnetic component size and weight.
This recommended scheme provides a foundational power device solution for 2-seater eVTOL air taxis, spanning from the high-voltage battery and motor drive to the low-voltage avionics network. Engineers can refine and adjust it based on specific propulsion architecture (e.g., distributed vs. centralized), cooling strategies (liquid/air/phase-change), and safety certification requirements (e.g., DO-254/DO-160) to build the robust, high-performance electrical systems that will underpin the safe commercialization of urban air mobility.

Detailed Topology Diagrams