HW/SW Codesign ProjectPWM Control IC

曾任輝林柏丞

Outline

• Buck Converter

• PWM IC

• A/C Converter

• PID regulator

• DPWM

• Simulation

• Summary

Buck Converter

PWM Control IC Block

IC Function

• A/D-----A complete analog controller could be simpler than a high-speed high-resolution A/D.

• PID regulator------ Available microcontroller/DSP systems are still too complex and costly.

• DPWM-----High-speed/ High-resolution digital pulse width modulators are needed.

Proper Resolution for A/D

-4

-3

-2

-1

0

1

23

4

Vref

Vo (max)

Vq

Vo

e

V Vq o

Static voltageregulation

PID regulator

• Control law for PID regulator : d[n]=d[n-1]+ae[n]+be[n-1]+ce[n-2]

DPWM resolution

DPWM

Behavior description for a buck switching converter by MATLAB/SIMULINK

Simulation Result

0 2 4 6 8

x 10-4

-0.5

0

0.5

1

1.5

2

2.5

Time(s)

cu

rre

nt(

A)

IL

0 2 4 6 8

x 10-4

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

1.8

Time (s)

vo

lta

ge

(V)

Vout

•Change of the output voltage (top) for the change of output current from 0.3A to 1A

•output voltage is regulated at 1.5v for a 3.3v input voltage

Summary

• Through loop analysis for the entire system, tune the parameters of the PID regulator to meet the loop bandwidth or adequate phase margin.

• Under a specification of the regulator, select the proper resolution of ADC and DPWM to avoid “limit cycling”.

• Supply regulator are widely used in communication, computer, consumer products.