SUMMARYA direct methanol fuel cell (DMFC) is highly anticipated as a new, high-density energy source for mobile usage; however, its poor power density presents a problem. As a result, the size of portable electronic equipment using DMFCs is far larger than that of equipment using another type of battery. In addition, steady power supply control is difficult, because the output power of the DMFC is affected by the environment. First, this paper presents a pulse charge control system that is a new control system applied to a mobile device, which uses the DMFC and an electric double layer capacitor (EDLC), then describes the new passive heat control and presents experimental results.

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A new maximum-power-point limiting (MPPL) control method for a direct methanol fuel cell (DMFC) was proposed. In regard to achieving MPPL, it was affirmed by experiment that it is possible to control the DMFC by simply ensuring that its voltage does not fall below a certain level regardless of its state. An MPPL control system that accomplishes the DMFC voltage limitation required for MPPL control by using a 'soft-start function' fitted in a ready-made DC/DC converter was developed. It was confirmed by experimental tests that the circuit board of the developed MPPL control system can perform DMFC voltage limitation control. 

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