ABSTRACT
Voltage-Mode Controller . . . . . . . . . . . . . . . . . . . . . 189 8.3 PWM-Based SM Voltage Controller for Boost Converters . . . . . . 191
8.3.1 Mathematical Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 8.3.2 Implementation of Controller . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192
8.3.2.1 Control Signal Computation . . . . . . . . . . . . . . . . . 192 8.3.2.2 Bandwidth of Ramp Voltage Generator . . . . . 192 8.3.2.3 Duty-Ratio Protection . . . . . . . . . . . . . . . . . . . . . . . 192
8.3.3 Experimental Prototype . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 8.3.4 Experimental Results and Discussions . . . . . . . . . . . . . . . . . . 194
8.3.4.1 Measured Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 8.3.4.2 Ensuring Duty-Ratio Protection . . . . . . . . . . . . . 194 8.3.4.3 Testing of Variable Ramp Signal Generation 195 8.3.4.4 Control Signals at Different Input Voltage . . . 196 8.3.4.5 Regulation Performance . . . . . . . . . . . . . . . . . . . . . . 198
of Switching Power
Performance with Peak Current-Mode Controller . . . . . . . . . . . . . . . . . . . . . 199
8.3.4.7 Operation in Discontinuous Conduction Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 202
In the previous two chapters, a general approach for designing the pulse-width modulation (PWM)-based SM voltage controllers for buck, boost, and buckboost converters has been expounded. In this chapter, we continue to discuss the design and implementation of the PWM-based SM voltage controllers, with emphasis on practical circuit design methods. It must be stressed that the design of these controllers at the circuit level involves a different set of engineering considerations. It is not an easy task especially if one aims to achieve a high level of accuracy using the simplest possible hardware for the circuit design. In addition to the circuit design, a practical approach to the design and selection of the sliding coefficients of the controller is introduced. This approach, which is based on Ackermann’s formula [1], permits the control design to be carried out systematically.
