Model of Direct Torque Control with Field Weakening

The Direct Torque Control with Field Weakening model is an advanced motor control algorithm particularly suitable for applications requiring wide speed range operation. This model combines the fast dynamic response characteristics of Direct Torque Control (DTC) with the high-speed extension capability of field weakening control, achieving optimized motor performance across the entire speed range.

The core of this model lies in simultaneously controlling two key variables: torque and flux. Conventional direct torque control is employed below base speed, while field weakening control mode automatically engages when speed exceeds the base speed. By dynamically adjusting the stator flux reference value in real-time, the motor can maintain output torque while overcoming voltage limitations, enabling high-speed operation.

This control model typically consists of three main modules: The flux observer calculates real-time motor flux position and magnitude using mathematical transformations and estimation algorithms; The hysteresis comparator generates switching signals for torque and flux through comparison with preset tolerance bands; The field weakening compensation module dynamically adjusts flux reference values in high-speed regions based on voltage and current measurements. The entire system utilizes Space Vector PWM modulation technology to achieve precise control of inverter switching states through optimized voltage vector selection and timing calculations.

The advantages of this control scheme include its independence from precise motor parameters, strong robustness against parameter variations, and maintenance of DTC's inherent fast torque response characteristics. In practical applications, this model is particularly suitable for electric vehicle drives, CNC machine tool spindles, and other scenarios requiring wide speed regulation ranges, where the control algorithm can be implemented using DSP or FPGA platforms with efficient interrupt service routines for real-time processing.