With the acceleration of industrial automation, industrial robots have become core equipment in flexible manufacturing lines. The servo drive, power supply, and auxiliary control systems, serving as the "muscles and nerves" of the robot, provide precise power conversion and motion control for key loads such as joint servo motors, brakes, and system controllers. The selection of power semiconductor devices (MOSFETs, IGBTs, SiC MOSFETs) directly determines system dynamic response, power density, thermal performance, and long-term reliability. Addressing the stringent requirements of robots for high torque, precision, robustness, and compactness, this article focuses on scenario-based adaptation to develop a practical and optimized device selection strategy.
I. Core Selection Principles and Scenario Adaptation Logic
(A) Core Selection Principles: Four-Dimensional Collaborative Adaptation
Device selection requires coordinated adaptation across four dimensions—voltage, loss, package, and reliability—ensuring precise matching with harsh industrial operating conditions:
Sufficient Voltage Margin: For mains-powered rectified buses (e.g., ~300V DC) or higher voltage servo systems (e.g., 600V DC), reserve a rated voltage withstand margin of ≥30-50% to handle voltage spikes and regenerative energy. For example, prioritize devices with ≥650V for a 400V DC bus.
Prioritize Low Loss & High Frequency: For motor drives, prioritize low conduction loss (Rds(on)/VCEsat) and low switching loss (Qg, Coss, trr) to improve efficiency, reduce heatsink size, and enable higher PWM frequencies for precise current control.
Package Matching: Choose high-power packages like TO-247, TO-263, or TOLL for main power stages, ensuring low thermal resistance. Choose compact packages like SOT223 or TO-252 for auxiliary controls, balancing power density and manufacturability.
Reliability Redundancy: Meet 24/7 operation with high peak loads. Focus on high junction temperature capability (e.g., 175°C), strong short-circuit withstand, and ruggedness against transients, adapting to demanding factory environments.
(B) Scenario Adaptation Logic: Categorization by Load Type
Divide loads into three core scenarios: First, Joint Servo Motor Drive (power & motion core), requiring high-current, high-efficiency, and fast-switching capability. Second, Auxiliary & Brake Control (safety & function), requiring robust switching for inductive loads like brakes and solenoids. Third, High-Voltage DC-DC / PFC Stage (power conversion), requiring high-voltage blocking and efficient switching at potentially high frequencies. This enables precise parameter-to-need matching.
II. Detailed Device Selection Scheme by Scenario
(A) Scenario 1: Joint Servo Motor Drive (1kW-5kW per axis) – Power & Motion Core
Servo drives require handling high continuous and peak currents (2-3x) with high switching frequency (10-50kHz) for precise torque control.
Recommended Model: VBGQA1803 (N-MOS, 80V, 140A, DFN8(5x6))
Parameter Advantages: SGT technology achieves an ultra-low Rds(on) of 2.65mΩ at 10V. Continuous current of 140A (peak >280A) easily handles high torque demands of joint motors. DFN8(5x6) package offers excellent thermal performance and very low parasitic inductance, crucial for high-frequency switching and minimizing voltage overshoot.
Adaptation Value: Drastically reduces conduction loss. For a 48V/2kW motor drive phase (approx. 42A avg), device conduction loss is minimal (<0.47W per FET in a bridge), enabling drive efficiency >98%. Supports high PWM frequencies for superior current ripple control, enhancing motion smoothness and positioning accuracy.
Selection Notes: Verify motor voltage, peak phase current, and required switching speed. Ensure PCB has sufficient copper area (≥300mm² per FET) and thermal vias for heat dissipation. Must be paired with a high-performance gate driver (≥2A sink/source) like ISO5852S or UCC5350 for optimal switching.
(B) Scenario 2: Brake & Auxiliary Solenoid Control (50W-500W) – Safety-Critical Switching
Electromagnetic brakes and solenoids are inductive loads requiring robust switching, often with high inrush current, and must be failsafe.
Recommended Model: VBE5415 (Common Drain N+P MOSFET, ±40V, ±50A, TO252-4L)
Parameter Advantages: Integrated symmetrical N and P-channel MOSFETs in a compact 4-lead package simplify H-bridge or high-side/low-side configurations for bidirectional control. Low and matched Rds(on) (14mΩ @4.5V) minimizes voltage drop and power loss. ±50A current rating provides ample margin for inrush currents.
Adaptation Value: Enables compact, efficient brake driver circuits. The common-drain configuration is ideal for building a monolithic half-bridge for quick brake engagement/release with minimal external components. Facilitates safe torque off (STO) functionality by providing a controlled discharge path for the brake coil.
Selection Notes: Calculate the steady-state and inrush current of the brake coil. A freewheeling diode (or use of the body diode with sufficient rating) is mandatory. Gate drivers should include charge pump or bootstrap for the high-side N-channel if used in a full bridge.
(C) Scenario 3: High-Voltage Bus DC-DC / PFC Stage (>3kW System Input) – Efficient Power Conversion
The input stage converting AC mains to a stable high-voltage DC bus requires high-voltage devices with good efficiency at elevated switching frequencies.
Recommended Model: VBQT165C30K (SiC MOSFET, 650V, 35A, TOLL-HV)
Parameter Advantages: Silicon Carbide (SiC) technology offers superior switching performance: very low Rds(on) (55mΩ @18V), negligible reverse recovery charge (Qrr), and high-temperature operation capability. 650V rating is ideal for 400V DC bus applications with margin. TOLL package provides low thermal resistance and low parasitic inductance.
Adaptation Value: Enables PFC or isolated DC-DC stages to operate at frequencies ≥100kHz, dramatically reducing the size of magnetics (inductors, transformers) and filters. Significantly reduces switching losses compared to Si Super-Junction MOSFETs or IGBTs, boosting full-load efficiency by 1-2% and reducing heatsink requirements. Enhances power density of the robot's cabinet-integrated power supply.
Selection Notes: Requires a dedicated high-speed gate driver (e.g., UCC5350, 1EDI20I12AF) capable of delivering strong gate currents with negative turn-off voltage for optimal SiC performance. Careful layout to minimize high-frequency loop inductance is critical.
III. System-Level Design Implementation Points
(A) Drive Circuit Design: Matching Device Characteristics
VBGQA1803: Pair with isolated gate driver ICs with high current capability (≥2A). Use low-inductance gate drive loops. Consider adding a small gate resistor (2-5Ω) to fine-tune switching speed and damp ringing.
VBE5415: For the N-channel side, a standard gate driver is sufficient. For the P-channel or high-side N-channel, ensure proper level shifting (bootstrap or isolated supply). Include TVS diodes on gate pins for ESD/ surge protection.
VBQT165C30K: Critical: Use a gate driver with negative turn-off voltage (e.g., -3 to -5V) to prevent parasitic turn-on due to high dv/dt. Implement active Miller clamp functionality if possible. Use Kelvin source connection for accurate gate control.
(B) Thermal Management Design: Tiered Heat Dissipation
VBGQA1803: Requires significant cooling. Use a dedicated heatsink or cold plate attached to the exposed pad. Ensure PCB copper pour is extensive and connected via multiple thermal vias.
VBE5415: Moderate heat dissipation needed. A well-designed PCB copper area (≥100mm²) under the tab may suffice for intermittent brake operation. For continuous duty, a small heatsink is recommended.
VBQT165C30K: Despite lower loss, high-frequency operation concentrates heat. Use a heatsink. The TOLL package's bottom cooling is highly effective; ensure good thermal interface material (TIM) contact to the heatsink.
Overall: Implement temperature monitoring (NTC or via driver IC fault) on all key power stages. Design for worst-case ambient temperature inside the robot control cabinet.
(C) EMC and Reliability Assurance
EMC Suppression:
VBGQA1803 / VBQT165C30K: Use low-inductance DC-link capacitors (film type) very close to the device terminals. Consider an RC snubber across drain-source to damp high-frequency ringing. Use shielded cables for motor connections with ferrite cores at both ends.
VBE5415: Use a snubber circuit (R+C) across the brake coil terminals to suppress voltage spikes during switching.
Reliability Protection:
Overcurrent Protection: Implement desaturation detection for IGBTs/MOSFETs using driver ICs with built-in DESAT protection (e.g., for VBGQA1803 in a bridge). Use shunt resistors or current sensors in each motor phase.
Overvoltage Protection: Use varistors and TVS diodes on the main AC input and DC bus. For regenerative braking, ensure the braking resistor and chopper circuit (using a device like VBP165R70SFD) are correctly sized.
Isolation & Grounding: Maintain proper creepage/clearance distances for high-voltage stages. Use a star-point grounding strategy to separate noisy power grounds from sensitive signal grounds.
IV. Scheme Core Value and Optimization Suggestions
(A) Core Value
High Performance & Efficiency: SiC in the input stage and SGT MOSFETs in the drive stage maximize system efficiency (>96% typical), reducing energy costs and thermal stress, enabling smaller enclosures.
Enhanced Motion Control: Low-loss, fast-switching devices enable higher servo bandwidth and smoother motion, improving robot speed and precision.
Robustness and Safety: Rugged devices and proper protection circuits ensure reliable operation in industrial environments. Integrated devices (VBE5415) simplify safety-critical brake control.
Optimized Power Density: Advanced packages (DFN, TOLL) and high-frequency operation allow for more compact drive and power supply designs.
(B) Optimization Suggestions
Power Scaling: For larger robots (>5kW axis), parallel VBGQA1803 devices or use higher current modules. For the main inverter, consider VBP165I60 (600V IGBT) for very high power, lower frequency (<10kHz) drives where its lower cost and high current (60A) are advantageous.
Higher Voltage Systems: For 600V+ DC bus systems, consider VBP165R70SFD (650V, 70A SJ MOSFET) as a high-performance Si alternative to SiC in the PFC stage.
Low-Power Auxiliaries: For sensor power, cooling fans, or low-power solenoids, VBJ1101M (100V, 5A, SOT223) offers a compact, cost-effective solution.
Specialized Brake Drivers: For very high current brake coils, use discrete high-current MOSFETs like VBMB1401 (40V, 200A) in a configured H-bridge, though it requires more board space.
Conclusion
Power semiconductor selection is central to achieving high performance, reliability, and compactness in industrial robot drive and power systems. This scenario-based scheme provides comprehensive technical guidance for R&D through precise load matching and system-level design. Future exploration can focus on wider adoption of SiC and GaN devices and the integration of sensing and protection into Intelligent Power Modules (IPMs), pushing the boundaries of robot power density and intelligence.

Detailed Topology Diagrams