25.9 : 相位超前控制的时域和频域解释

Consider adjusting the brightness on a television screen. When the contrast is enhanced, a phase-lead controller is at work.

Mathematically, if the first parameter is smaller than the second, it signifies phase-lead control.

Phase-lead control design involves careful placement of pole and zero values to maintain steady-state error and enhance system stability.

Shifting the zero nearer to the origin enhances system response speed and settling time but may amplify maximum overshoot. Positioning the pole further reduces overshoot, yet if it is too distant, it may slow response and increase settling time.

When appropriately used, phase-lead control can enhance system damping and improve response speed and settling times without affecting the steady-state error.

The interpretation through the frequency domain commences by constructing a Bode plot of the uncompensated process.

Estimating the maximum phase value enables the calculation of 'a'. With this set, the design is near completion, only requiring the determination of 'T.'

Corner frequencies are strategically placed to aid the phase margin. Once specifications are met, the controller's transfer function is established.