Optimal Inductor Current in Boost DC/DC Converters Operating in Burst Mode Under Light-Load Conditions

Abstract

Abstract-This letter analyses how the efficiency of boost DC/DC converters operating in burst mode under light-load conditions can be improved by an appropriate selection of the inductor current that transfers energy from the input to the output. A theoretical analysis evaluates the main power losses (fixed, conduction and switching losses) involved in such converters and how do they depend on the inductor current. This analysis shows that there is an optimal value of this current that causes minimum losses and, hence, maximum efficiency. These theoretical predictions are then compared with experimental data resulting from a commercial boost DC/DC converter (TPS61252) whose average inductor current is adjustable. Experimental results show that the use of the optimal inductor current, which was around 340 mA for an output voltage of 5 V, provides an efficiency increase of 7%.

Optimal Inductor Current in Boost DC/DC Converters Regulating the Input Voltage Applied to Low-Power Photovoltaic Modules

“…A second example is the burst mode (BM) where the transistors are cyclically switched on and off at a fixed frequency (the same as in PWM) during an active period, but they are permanently in off-state during an inactive period, which becomes longer as the load current decreases [10]. During the active period, it is advisable to transfer the energy from the battery to the electronics at an optimal value of inductor current that can offer an efficiency increase of 10% [11].…”

“…The power processing circuits in [15,16,17] employed a commercial dc/dc converter (LT1303 [18], MAX1675 [19], and MAX1795 [20]) that adjusted the inductor current around 1 A, 0.5 A, and 0.25 A during the active period, respectively. However, the value of that current was not selected in terms of efficiency A maximization, as proposed in [11] for the regulation of the output voltage. This paper focuses on dc/dc converters operating in BM and regulating their input voltage.…”

“…On the other hand, at the output, we assume rechargeable batteries that are charged through the dc/dc converter. Following the method suggested in [11], which was applied to dc/dc converters regulating their output voltage, this paper aims to improve the power efficiency of the converter by selecting an optimal value of the inductor current employed to transfer the energy from the transducer to the batteries. Such a case requires a novel study of the dc/dc converter because the independent input/output variables are not the same as in [11].…”

“…Following the method suggested in [11], which was applied to dc/dc converters regulating their output voltage, this paper aims to improve the power efficiency of the converter by selecting an optimal value of the inductor current employed to transfer the energy from the transducer to the batteries. Such a case requires a novel study of the dc/dc converter because the independent input/output variables are not the same as in [11]. Whereas in [11] these variables were the output power (voltage and current) demanded by the load and the input voltage provided by the battery, here these are the input power (voltage and current) generated by the energy transducer and the output voltage provided by the battery.…”

“…Such a case requires a novel study of the dc/dc converter because the independent input/output variables are not the same as in [11]. Whereas in [11] these variables were the output power (voltage and current) demanded by the load and the input voltage provided by the battery, here these are the input power (voltage and current) generated by the energy transducer and the output voltage provided by the battery. Furthermore, in comparison with [11], this paper also contributes with the following.…”