With the rapid development of rehabilitation medicine and assistive robotics, high-end rehabilitation assessment robots have become crucial equipment for enhancing rehabilitation efficiency and precision. Their actuation system, power management, and safety control circuits demand power semiconductor devices that offer high efficiency, high reliability, and precise control. The selection of Power MOSFETs and IGBTs is pivotal in determining the system's dynamic response, power density, operational safety, and service life. Addressing the stringent requirements of rehabilitation robots for torque control accuracy, operational smoothness, safety redundancy, and electromagnetic compatibility (EMC), this article reconstructs the device selection logic based on application scenario adaptation, providing an optimized, ready-to-implement solution.
I. Core Selection Principles and Scenario Adaptation Logic
Core Selection Principles
High Voltage & Current Ruggedness: For mains-powered systems or high-power motor drives, devices must withstand high bus voltages (e.g., 300V+ DC link) and surge currents, with sufficient voltage/current derating.
Optimized Switching & Conduction Performance: Prioritize low on-state resistance (Rds(on)) and favorable switching characteristics (low Qg, Qgd) to minimize losses in high-frequency PWM motor drives and ensure smooth motion control.
Robust Package & Thermal Capability: Select packages like TO-247, TO-263 for high-power paths to ensure effective heat dissipation under continuous or peak loads, critical for maintaining performance and reliability.
Safety & Functional Isolation: Implement devices enabling safe torque disable, independent module power control, and fault isolation to meet the highest safety standards (e.g., IEC 60601-1) for medical-adjacent applications.
Scenario Adaptation Logic
Based on the core subsystems within a rehabilitation assessment robot, power device applications are divided into three primary scenarios: High-Power Joint Actuator Drive (Core Motion), System Safety & Power Distribution (Safety-Critical), and Precision Sensor/Control Module Supply (Low-Noise), with device parameters matched accordingly.
II. MOSFET Selection Solutions by Scenario
Scenario 1: High-Power Joint Actuator Drive (500W-1500W) – Core Motion Device
Recommended Model: VBP165R38SFD (Single-N MOSFET, 650V, 38A, TO-247)
Key Parameter Advantages: Utilizes advanced SJ_Multi-EPI (Super Junction) technology, achieving an exceptionally low Rds(on) of 67mΩ at 10V Vgs. The 650V rating is ideal for 3-phase 220V AC input systems after rectification. A continuous current rating of 38A supports high-torque joint actuators.
Scenario Adaptation Value: The TO-247 package offers excellent thermal impedance, facilitating heatsink attachment for managing high power dissipation. Ultra-low conduction loss minimizes heat generation in the inverter bridge. Superior switching performance enables high-frequency sine-wave PWM control, resulting in smooth, quiet, and highly dynamic motor operation essential for precise patient motion assessment and assistance.
Applicable Scenarios: Main inverter bridge for brushless DC (BLDC) or Permanent Magnet Synchronous Motor (PMSM) drives in robotic joints (e.g., elbow, knee actuators).
Scenario 2: System Safety & Power Distribution – Safety-Critical Device
Recommended Model: VBMB2309 (Single-P MOSFET, -30V, -65A, TO-220F)
Key Parameter Advantages: Features an ultra-low Rds(on) of 9mΩ at 10V Vgs, minimizing voltage drop in power paths. High continuous current rating of -65A. A moderate gate threshold (Vth = -2.5V) ensures robust turn-on/off.
Scenario Adaptation Value: The P-MOSFET is ideal for high-side load switching. It can be used for centralized enable/disable control of actuator groups or critical subsystems (e.g., entire limb module). Its very low Rds(on) ensures minimal power loss even under high current. This allows for implementing safe torque off (STO) functionality or emergency power isolation, a critical safety feature. The TO-220F (fully isolated) package simplifies heatsinking and improves isolation safety.
Applicable Scenarios: Main power rail switching, safety enable/disable circuits for actuator clusters, or as a pass element in active braking circuits.
Scenario 3: Precision Sensor & Control Module Supply – Low-Noise Device
Recommended Model: VBR9N6010N (Single-N MOSFET, 60V, 2A, TO-92)
Key Parameter Advantages: Low voltage rating (60V) suitable for 12V, 24V, or 48V auxiliary buses. Very low gate charge (Qg) characteristic of Trench technology ensures clean switching. Can be driven directly by 3.3V/5V MCU GPIO (Vth=1.3V). Rds(on) of 110mΩ (10V) is excellent for its package.
Scenario Adaptation Value: The small TO-92 package saves board space for dense control PCBs. Its low-noise switching performance is crucial for not interfering with sensitive analog sensors (force, EMG, position). Enables precise power sequencing and management for sensor arrays, data acquisition modules, and communication interfaces (EtherCAT, etc.), supporting high-fidelity data collection and system intelligence.
Applicable Scenarios: Low-side switching for sensor power rails, load switches in DC-DC converter circuits, or control of small auxiliary fans/pumps.
III. System-Level Design Implementation Points
Drive Circuit Design
VBP165R38SFD: Must be paired with a dedicated gate driver IC (e.g., with 2A+ source/sink capability) featuring desaturation detection and fault reporting. Use Kelvin connection for gate drive if possible. Optimize PCB layout to minimize high-current loop inductance.
VBMB2309: Requires a level-shift or charge-pump circuit for high-side driving. A simple bootstrap circuit with a dedicated high-side driver channel is typical. Ensure fast turn-off for safety response.
VBR9N6010N: Can be driven directly from MCU GPIO. A small series gate resistor (e.g., 10-100Ω) is recommended to damp ringing and limit current.
Thermal Management Design
Hierarchical Strategy: VBP165R38SFD requires a dedicated heatsink possibly coupled to the robot's structural frame. VBMB2309 may need a small heatsink or thermally conductive pad to the chassis depending on load duty cycle. VBR9N6010N typically relies on PCB copper pour.
Derating & Margins: Operate devices at ≤70-80% of their rated current in continuous mode. Ensure junction temperature (Tj) remains below 110°C with a 15-20°C margin at maximum ambient temperature (e.g., 40°C).
EMC and Reliability Assurance
EMI Suppression: Use RC snubbers or ferrite beads near the VBP165R38SFD drain terminals. Ensure proper shielding of motor cables. Place decoupling capacitors close to the VBR9N6010N drain for sensor power cleanliness.
Protection Measures: Implement comprehensive overcurrent (OC), overtemperature (OT), and short-circuit (SC) protection at the inverter stage for VBP165R38SFD. Use TVS diodes on all gate drivers and sensitive supply rails. Incorporate redundant feedback (e.g., dual current sensors) in safety-critical drives.
IV. Core Value of the Solution and Optimization Suggestions
The power device selection solution for high-end rehabilitation assessment robots, based on scenario adaptation, achieves comprehensive coverage from high-power motion generation to intelligent safety management and low-noise signal integrity. Its core value is reflected in three key aspects:
High-Fidelity Motion & Energy Efficiency: The use of low-loss SJ-MOSFETs (VBP165R38SFD) in the main drive ensures high efficiency (>97% inverter efficiency possible), reducing thermal stress and enabling more compact joint designs. This directly translates to longer operational periods, smoother torque delivery for precise patient interaction, and lower system cooling requirements.
Enhanced Functional Safety & System Robustness: The strategic use of a high-current P-MOSFET (VBMB2309) for power distribution enables architecturally simple yet highly effective safety function blocks. This facilitates compliance with safety standards by providing reliable means for emergency stop and fault isolation. Combined with the robust packages selected, the system achieves high mean time between failures (MTBF), which is paramount for medical environments.
Optimal Balance of Performance, Integration & Cost: The solution leverages a mix of advanced SJ technology for core performance and mature, cost-effective trench/planar devices for supporting functions. This tiered approach optimizes the total system cost without compromising critical performance or safety. The selected packages are industry-standard, ensuring good supply chain availability and ease of manufacturing.
In the design of power drive and management systems for high-end rehabilitation assessment robots, the selection of switching devices is a cornerstone for achieving precision, safety, and reliability. This scenario-based selection solution, by accurately matching device characteristics to specific load and control requirements—complemented with rigorous system-level design—provides a comprehensive and actionable technical roadmap. As rehabilitation robots evolve towards greater autonomy, adaptability, and human-robot collaboration, future device selection will increasingly focus on integrated power modules (IPMs) with built-in drivers and protection, and the exploration of wide-bandgap semiconductors (SiC, GaN) for even higher efficiency and power density. This will lay a solid hardware foundation for the next generation of intelligent, responsive, and trustworthy rehabilitation robotics, ultimately contributing to more effective and accessible patient care.

Detailed Topology Diagrams