CPC H02J 50/40 (2016.02) [H02J 50/10 (2016.02); H02J 50/90 (2016.02); H02J 2310/22 (2020.01)] | 20 Claims |
1. A method comprising:
applying a plurality of detection signals to a plurality of receivers;
receiving a plurality of echo signals resulted from the plurality of receivers;
comparing the plurality of echo signals with a predetermined echo signal distribution pattern;
determining the number of the plurality of receivers through comparing a distance between a first group of echo signals and a second group of echo signals with a predetermined threshold value if the plurality of echo signals comprises two groups of echo signals, and comparing the number of echo signals with a threshold number of echo signals in one group if the plurality of echo signals comprises one group of echo signals; and
charging the plurality of receivers sequentially using a movable transmitter.
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