HEMS with resonant-type wireless power transmission

In recent days the demand for saving energy consumption is increasing day by day. HEMS is expected as one of the useful technology to satisfy that demand. Though it is understood useful and used on some situations, it has not prevailed well into the public. The reason is considered to be high initial cost of the equipment, low mobility of the system and regrettable unconcern for saving energy. In order to change the situation, we propose to introduce sensor network system into HEMS. We are studying energy harvesting technology for the non-maintenance sensor network system. Energy harvesting involves many kind of sources based on heat, light, vibration and so on. Such kind of sources need suitable environment to generate enough electrical energy. But in the home, there are quite a few places difficult to find suitable energy source. We consider, however, the wireless power transmission can give energy to the sensor network nodes at any condition and at any time. Thus, we have studied the resonant-type wireless power transmission method to assist the energy harvesting sensor network nodes. In this paper, we will clarify the power transmitting efficiency according to the coil dimension and transmitting length, and we propose the way to realize practical HEMS system.