Simulation Design of Dual Closed-Loop DC Speed Regulation System

The dual closed-loop DC speed regulation system is a widely adopted motor control solution in industrial automation, featuring a dual feedback mechanism comprising current and speed loops for precise speed adjustment. This article utilizes Matlab simulation tools to dissect the design workflow and key implementation strategies of this system.

Structurally, the dual-loop design typically consists of an inner loop (current loop) and an outer loop (speed loop). The current loop, serving as the inner loop, primarily regulates the motor's armature current to ensure rapid response to load variations. The speed loop, as the outer loop, stabilizes motor speed by adjusting the reference input to the current loop. Both loops employ PID controllers for closed-loop regulation, requiring parameter tuning that balances dynamic response and disturbance rejection capabilities.

During simulation implementation, the first step involves constructing mathematical models for the motor, power converter, and load in Matlab/Simulink. The motor model must account for armature resistance, inductance, and back EMF characteristics, while the PWM converter can be simplified using an ideal switch model. Subsequently, closed-loop control modules for both current and speed loops are built. By debugging PID parameters (e.g., proportional gain, integral time) and observing the system's step response curves, overshoot and settling time can be optimized through iterative simulation runs.

Typical test scenarios include sudden load disturbances and step changes in reference speed. Comparing simulation results between single-loop and dual-loop configurations visually demonstrates the advantages of dual-loop design in disturbance rejection and tracking performance. Finally, Matlab's frequency domain analysis tools (such as Bode plots) can further validate the system's stability margins.

This simulation approach is not only suitable for educational demonstrations but also serves as a preliminary research method for parameter tuning in practical speed regulation systems. By adjusting model parameters (such as moment of inertia and inductance values), system performance under different operating conditions can be rapidly evaluated through parameter sweeps and batch simulation techniques.