What are the best methods to model and control electric motor torque for hybrid vehicles?

1 Torque generation

Electric motors generate torque by applying a current to the windings of a rotor, which interacts with a magnetic field from a stator. The amount of torque depends on the current, the number of windings, the geometry of the rotor and stator, and the speed of the motor. To model the torque generation, you need to know the parameters of the motor, such as its resistance, inductance, flux linkage, and back electromotive force. You can use mathematical models, such as the dq model or the Park transformation, to simplify the analysis of the motor dynamics.

2 Torque control

To control the torque output of the electric motors, you need to regulate the current supplied to them. This can be done by using power electronics, such as inverters, converters, and switches, to adjust the voltage and frequency of the current. You can use different control strategies, such as scalar control, vector control, or direct torque control, to achieve different objectives, such as speed regulation, torque optimization, or efficiency improvement. You also need to consider the limitations of the power electronics, such as the switching frequency, the harmonic distortion, and the thermal stress.

3 Torque distribution

Hybrid vehicles can have different configurations of electric motors and internal combustion engines, such as parallel, series, or power-split. Depending on the configuration, you need to decide how to distribute the torque among the different power sources, and how to coordinate them. You can use different criteria, such as fuel consumption, emissions, performance, or drivability, to optimize the torque distribution. You also need to consider the constraints of the power sources, such as the battery state of charge, the engine operating range, and the transmission ratio.

4 Torque vectoring

Torque vectoring is a technique that allows you to control the torque applied to each wheel of a vehicle independently. This can improve the handling, stability, and safety of the vehicle, especially in cornering, braking, or slippery conditions. You can use electric motors to perform torque vectoring, either by having one motor per wheel, or by using a differential or a clutch to split the torque from a single motor. You can use different algorithms, such as yaw rate control, slip control, or optimal control, to determine the optimal torque vectoring for each situation.

5 Torque feedback

Torque feedback is a way of providing information to the driver about the torque output of the electric motors and the internal combustion engine. This can enhance the driving experience, the comfort, and the awareness of the driver, especially in hybrid vehicles where the torque response may be different from conventional vehicles. You can use different methods to provide torque feedback, such as haptic devices, auditory signals, or visual displays. You also need to consider the human factors, such as the perception, preference, and adaptation of the driver.

6 Torque challenges

Torque modeling and control for hybrid vehicles presents several challenges to vehicle dynamics, such as the complexity and nonlinearity of motor dynamics and power electronics, the trade-off between different control objectives and constraints, the interaction between torque and other vehicle subsystems, and the uncertainty of driving conditions and driver behavior. Additionally, the reliability and robustness of torque sensors and actuators must be taken into account.

7 Here’s what else to consider

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