This paper deals with the design of the power management circuit for the vibration generator developed in the frame of
the European WISE project and its testing in the connection with the generator and the dynamic load simulating the real
load. This generator is used as an autonomous energy source for wireless sensor applications. It can be used for example
in the aeronautic, automotive and many other applications. The generator output power analysis was based on the
vibration spectrum measured on the helicopter engine, provided by the consortium EADS, EUROCOPTER,
DASSAULT AVIATION - 6.RP -WIreless SEnsing (WISE) project. This spectrum shows very unstable vibration levels.
It was done the statistical analysis of these vibration levels and it was shown that there is a need of the power
management circuit, which can provide a stable output voltage for the supplied circuit and if there is a need it can store
an immediately unusable generated energy. The generator can't be used as the only energy source for the sensor circuit,
because there are not any vibrations when for example a motor is stopped. In these periods and in the time of low
vibration levels the circuit must be supplied from battery.
The power management circuit described in this paper fulfills these requirements. It has two power inputs - the battery
and the generator. It can switch between them at certain defined generator output levels by the threshold detector. Also
when there is too much of the generated power, it can store the extra energy in the storage for the later usage. The
storage device is the advanced capacitor. The advanced capacitor is a device containing three capacitors. These
capacitors are connected (and charged) sequentially so the increasing capacity is provided.
The developed power management was tested in the connection with the real vibration generator raised by stable
vibration levels and the dynamic load simulating the real sensor in the main operation stages - sampling and data
transmitting. It was shown that the generator with output power of 8mW@0,3GRMS with generator weight of 140g
together with the described power management circuit can save about 50% of battery energy with the mentioned
vibration spectrum. The generator used for the testing was improved, so it is more sensitive and also the sensor power
requirements were decreased, so now it can be saved up to 100% battery energy during the generator operation. Also the
power management circuit is still refined.