Improving the Efficiency by Controlling the Switching Frequency for Secondary‐Side Converter of an Inductive Power Transfer System

Abstract

SUMMARY The switching frequency affects the efficiency of a secondary‐side converter that is configured with a diode bridge rectifier connected to a DC‐DC converter in an inductive power transfer (IPT) system. The efficiency characteristics for the switching frequency of a secondary‐side converter were analyzed theoretically in order to establish a highly efficient control scheme the controls the switching frequency of the converter. A control scheme is proposed in which the switching frequency of the secondary‐side converter is controlled according to the efficiency characteristics. The validity of the proposed control scheme was clarified through experiments. The results showed that the proposed control scheme improved the efficiency of the IPT system by 3.4 points compared to the conventional control scheme.

A Consideration on Maximum Efficiency of Resonant Circuit of Inductive Power Transfer System with Soft-Switching Operation

“…In Figure 6, I charge becomes larger, i.e., the output power becomes larger, on the range where α 1 and α 2 are set to smaller values. As shown in Figure 6, the loci of the maximum efficiency points are in accordance with (17) when E 2 /E 1 does not deviate from one, which is the requirement for high efficiency based on (12). This is because the influence of (11) becomes more dominant than the influence of (12) on the efficiency.…”

“…In condition (17), the power factor of the resonant circuit becomes the highest because the difference of the phases between the voltages and the currents becomes the smallest. Therefore, the efficiency of the resonant circuit becomes higher.…”

“…Thus, the influence of (12) can be ignored when E 2 /E 1 does not deviate far from (12). On the other hand, when E 2 /E 1 deviates further from (12), the locus of the maximum efficiency points deviate from the line expressed by (17). Therefore, a novel equation considering the influence of (12) is necessary when the influence of (12) can not be ignored.…”

“…Previously, the maximum-efficiency-tracking method for the resonant circuit [2,[7][8][9][12][13][14][15], the design method for the resonant circuit [2,11,16], the switching frequency control method for the secondary-side converter [14,17], and the soft-switching technique [9,15,[18][19][20] were proposed as the efficiency improvement method for IPT systems. In general IPT systems, much electromagnetic noise and power loss occur because the converters of IPT systems are driven in high switching frequency by tens of kHz.…”

Development of dynamic wireless power transfer system for vehicle logistics robot

“…Static WPT schemes were proposed, and in part realized, for indoor AGV applications. [5][6][7] DWPT was studied for automobiles, [8][9][10] and contact-type power supply was proposed as well. 11 As regards contact-type chargers, there are concerns about failures caused by wear in charger terminals during static charging of conventional AGVs; thus, a wireless scheme is adopted in this study.…”