About the distinctive characteristics of DC-DC switch-mode converters under discontinuous conduction mode

Operation of DC-DC switch-mode converters under discontinuous conduction mode has been analyzed by energy balancing method. The approach calculates the energy balance between the input and output power during each operating period. The results of analysis show that DC-DC converters give several distinctive input and output characteristics, under discontinuous conduction mode. For examples, a boost DC-DC converter acts as a CRL (current regulated load), which absorbs designated current from the original DC source. The current is given by a CRL-function, which is the function of system parameters. Depending on these distinctive characteristics, a simple maximum power point tracking control system for solar cell has been proposed, as the example. The system has been designed according to the CRL-function. No feedback control is necessary, and the system is easy to design and operates stable. Another example of free-running boost converter for composing power factor correcting rectifier has also bee described. These examples show the usefulness of the CRL-function. Although their control procedures arc simple, their operations show excellent performance, depending on the simulation results