Torque Sensor

Overview

Torque sensors play a critical role in electric vehicles by bridging mechanical forces with digital control. While speed and voltage sensors measure motion and electrical states, torque sensors capture the instantaneous load or twist being applied in the drivetrain, steering column, or motor shaft. This data is essential for fine-tuning propulsion, improving regenerative braking, and ensuring responsive handling.

In EVs, torque sensors enhance efficiency and safety by enabling adaptive torque management. They are integrated into systems such as electric power steering (EPS), drive motor control, and torque vectoring differentials. With EVs delivering high torque at low rpm, monitoring and regulating this force becomes central to maintaining traction, protecting components, and optimizing performance.

How Does It Work?

Torque sensors measure rotational force through mechanical strain or magnetic effects and convert it into an electrical signal for control units:

1. Strain Gauge Sensors: Bonded to a rotating shaft, strain gauges detect minute deformations as torque is applied. Changes in resistance are translated into torque values.

2. Magnetostrictive Sensors: Torque-induced stress alters the magnetic properties of the shaft. This change is detected by magnetic coils or sensors.

3. Optical and Inductive Sensors: Use light beams or electromagnetic fields to measure angular displacement caused by torque.

In EVs, these signals are processed by the Vehicle Control Unit (VCU) or Electric Power Steering Control Unit, ensuring motor torque aligns with driver input, load conditions, and road dynamics. The result is smoother acceleration, precise steering feedback, and intelligent torque distribution.

Features of Torque Sensor

• High Accuracy & Sensitivity: Detects small torque variations critical for fine control in steering and propulsion systems.

• Real-Time Response: Enables millisecond-level adjustments for stability, traction, and motor efficiency.

• Non-Contact Operation (in advanced designs): Reduces wear and increases durability in high-torque EV applications.

• Compact & Lightweight: Designed to integrate seamlessly into EV drivetrains and steering systems without adding significant mass.

• Robust Durability: Built to withstand vibration, high torque loads, and wide temperature ranges.

• Digital Communication: Outputs processed torque values via CAN, LIN, or other automotive-grade communication protocols.

• Functional Safety: Incorporates redundancy and plausibility checks to comply with ISO 26262 standards.

Applications in EV

Torque sensors are embedded across multiple EV subsystems:

• Motor Control: Feedback from torque sensors allows the inverter to adjust phase currents, ensuring smooth torque delivery and efficient use of battery energy.

• Electric Power Steering (EPS): Measures driver-applied torque on the steering wheel, enabling assisted steering while preserving natural road feel.

• Torque Vectoring: Distributes torque between wheels in performance EVs, improving cornering stability and handling dynamics.

• Regenerative Braking: Sensors help balance regen torque with friction braking for smooth deceleration and energy recovery.

• Drivetrain Protection: Monitors excessive torque spikes, preventing damage to shafts, gears, or couplings under high loads.

• Commercial EV Fleets: Used in predictive maintenance by tracking torque patterns that may indicate drivetrain wear or misalignment.

For example, premium EVs like Audi e-tron and Porsche Taycan utilize torque sensors in their torque vectoring systems to achieve both performance and stability.

Conclusion

The torque sensor is a precision enabler of EV drivability. By continuously measuring rotational force and feeding real-time data into control systems, it ensures optimized energy usage, smoother acceleration, accurate steering, and safer operation. In the EV ecosystem, torque sensors are indispensable for achieving the perfect balance between performance, efficiency, and safety.