Motor Modeling and Simulation

Motor modeling and simulation help engineers perform tasks ranging from analyzing system-level performance of a motor to developing a detailed electric motor control system. Depending on the task, different physical effects need to be represented by the motor simulation model. System engineers analyze motors within a larger system and need more abstract motor models that simulate fast and provide information such as torque and power. Motor control engineers need motor models that capture the effects of changes in voltage and current.

Simulink^® and Simscape Electrical support multiple fidelity levels of motor modeling and simulation to accommodate various applications, such as motor sizing and electric vehicle traction motor control design. Various levels of motor model fidelity ensure that engineers can choose the right level of detail required for their specific application.

Modeling for System Design

System design motor modeling and simulation aims to capture the motor's performance under different working conditions and predict the motor's energy consumption in its operating range. In this scenario, engineers use simplified dynamics of the system behavior that includes:

• No pulse-width modulation (PWM) or power electronic switching
• Energy-based, steady-state equivalent, and efficiency map modeling

For this simplified motor modeling approach, you can use the Motor & Drive (System Level) block, which represents a generic motor through a range of torques and speeds. This provides a torque-speed envelope that captures the motor's overall behavior while making the system easier to model and simulate, resulting in faster simulations while still providing accurate predictions on losses.

Modeling for Motor Drive Design

Control system design plays an essential role in managing the speed, torque, and energy consumption of electric motors for industrial motor drive applications. To prioritize control design and enable faster simulation while maintaining accuracy, engineers develop optimized and reliable motor control systems using motor models that incorporate:

• Ideal switching
• Lumped parameter modeling
• Linear torque-current relationship

For easing lumped-parameter motor modeling, Simscape Electrical provides pre-parameterized motor blocks that contain manufacturers’ motor data. If manufacturers’ data is not available, Motor Control Blockset™ enables you to run instrumented tests to estimate motor parameter values.

Modeling for Traction Motor Applications

Accurate, high-fidelity motor models let you replicate nonlinear behaviors for electric vehicle applications when traction motor energy losses reduce vehicle range. Unlike using a linear lumped-parameter motor model, engineers can incorporate motor simulation results from finite element method (FEM), which includes nonlinear mapping between rotor position, flux linkage, current, and torque. The highest-fidelity motor simulation can be achieved using additional FEM data, including spatial harmonics, to facilitate the development of torque ripple mitigation algorithms and optimize motor control efficiency. For accurate representation of traction motor control system, engineers use:

• Non-ideal switching – physics-based modeling of power semiconductors.
• Saturation – nonlinear dependence on current and/or rotor angle.
• Spatial harmonics – including torque ripple caused by cogging and harmonics in the flux linkage.

The use of high-fidelity motor modeling helps control engineers investigate extreme operating conditions using simulation with Simulink. To achieve high-fidelity motor modeling and co-simulation of motor models for validation, engineers can import FEA data from third-party tools such as ANSYS Maxwell, Motor-CAD, and JMAG-RT into Simscape Electrical FEM parameterized motor block.

To learn more about motor modeling and simulation with MATLAB and Simulink, see Simscape Electrical and Motor Control Blockset.