Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With discharge of cells or batteries
Patent
1983-06-24
1986-11-11
Hickey, R. J.
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With discharge of cells or batteries
322 2A, 330 45, 330 7, H02N 108
Patent
active
046225102
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a parametric electric machine comprising at least one capacitor having a capacity which is variable as a function of time and connected in series with an inductor, which comprises at least one induction coil, and a resistor.
STATE OF THE ART
It has already been proposed to convert mechanical energy to electrical energy by a periodic change of the electric parameters of a resonant circuit. In one such "parametric generator", a series resonant circuit comprises a capacitor and an induction coil and the capacitance is periodically varied. As the capactiance of the capacitor is reduced, its charge is condensed into a smaller space, to obtain a smaller capacitance. Work must be performed for this purpose. In that case the energy source is the mechanism which decreases the capacitance. For an increase of the capacitance it is not necessary to supply energy to the system because the charges having like signs repel each other and automatically occupy a larger space on the increased capacitance. For this reason, a periodic decrease and increase of the capacitance involves only a flow of energy from the drive mechanism into the resonant circuit (conversion of mechanical energy to electromagnetic energy).
A parametric generator can be expected to afford some advantages over conventional generators, the operation of which is based on induction and which either comprise permanent magnets (such as a bicycle dynamo) or generate the required magnetic field by exciting coils having windings which generate heat by the Joule effect. The resulting losses are so high that a direct water cooling is necessary in generators above a certain power. Considerable losses due to a generation of heat may arise also in the rotor windings. On the other hand, the parametric generator is free from losses which are due to a generation of heat and the generator can be used for a direct generation of relatively high voltages (in the kilovolt range). Additional advantages are the simple structure and the light weight of a parametric generator.
But the previous attempts to build a parametric generator have failed. It has not been possible to generate a periodic alternating current which is not dependent on the changing loads presented by the consumers but there have been exponentially increasing currents, which caused the induction coils to burn out, or the alternating current oscillation was quickly damped. It was also not possible to generate sinusoidal alternating current oscillations with a parametric generator. The reason for this fact becomes apparent upon a consideration of the differential equation for the parametric resonant circuit having a capacitance which varies as a function of time: ##EQU2## wherein L.sub.o is the inductance, which is assumed to be constant (at first instance) and C.sub.o is the mean total capacitance defined by C.sub.o =(C.sub.max +C.sub.min)/2, wherein C.sub.max is the highest and C.sub.min the lowest capacitance. The capacitance change is expressed as .DELTA.C=(C.sub.max -C.sub.min)/2. R.sub.o is the resistance of the inductor and is constant (in the first instance) and Q(t) is the charge on the capacitor.
The differential equation (I) is a damped Mathieu's differential equation, which generally has unstable solutions. This means that the voltage, charge and current exhibit an exponential approach to infinity or zero. A stable periodic oscillation is obtained only at certain values of the parameters R.sub.o, L.sub.o, C.sub.o and .DELTA.C but that oscillation varies as a Mathieu function rather than as a sine function of time. And there is hardly a power supply system which will accept voltages varying as a Mathieu function of time.
To eliminate that disadvantage, it has been proposed in German Patent Specification No. 633,259 to apply a sinusoidal alternating current voltage to a parametric resonant circuit having a variable capacitance or inductance and to force that circuit to increase that separate excitation by parametric effects ("power amplifier").
SUMMARY OF THE INVENTION
REFERENCES:
patent: 2540327 (1951-02-01), Felici
patent: 3094653 (1963-06-01), Le May et al.
patent: 4054826 (1977-10-01), Wahlstrom
patent: 4096393 (1978-06-01), Sher
Light Metals, London, (GB) Nov. 1946, "Aluminium and Magnesium in the Electrical Industries" pp. 611-613.
Hickey R. J.
Kelman Kurt
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