Two inversely ganged variable capacitors having a common movable element varying the capacities such that when one capacitor is at maximum capacitance, the other is at minimum capacitance, have, after initially charging, a substantially constant contained or trapped charge distributed between the two capacitors. As the capacities of the capacitors are varied, a potential difference is developed between the fixed plate of one capacitor and the fixed plate of the other. When these two potential points are connected to a load, charge is transferred from one capacitor to the other as a current flow through the load. The total charge is not diminished, the energy supplied the load being the energy expanded on moving the movable charged plates. As the movable plates are moved in a cyclic manner an alternating current is provided to the load.

A parametric electric machine consists of a series resonant circuit, which has a capacitance (C) which is adapted to be mechanically varied, an inductance (L) and a resistance (R). The no-load values of the capacitance (C.sub.o), inductance (L.sub.o) and resistance (R.sub.o) fulfill the threshold condition ##EQU1## and at least one of the parameters L, R and C of the resonant circuit is a function of the current flowing in the resonant circuit.

The invention concerns a recharging device (4), comprising and consisting of photovoltaic sensors (5), alveolar lens particles (11), light energy amplifier (6), electronic management unit (7), magnetic counter-weight (17), steel balls (18), spring mechanism (22) with its manual butterfly winder (23), alternator (25) and battery (2), consisting in a single extra flat system, comprising several forms of recharging and in all conditions and all positions, inserted and fixed, matching the shape of the mobile (cellular) portable telephone (1), or on the protective case (21), or on a battery (2) or any other communication means comprising a transmitter-receiver, providing them with autonomy, causing them to operate by delivering voltage and electric current (13) so as to recharge them, maintain them and enabling them to operate, using daylight (10), artificial lighting (8), vibrations (20), movements (19) and the spring manual winder.

A method of controlling a battery car in which a motor is driven by a battery and the battery is charged with regeneration power generated by deceleration torque comprises the steps of charging a large-capacitance capacitor connected in parallel with the battery and the motor while restricting a current flowing from the battery to the large-capacitance capacitor, when the voltage of the large-capacitance capacitor is lower than a first voltage, charging the battery to a preset voltage while restricting a current flowing from the large-capacitance capacitor to the battery, when a charging voltage of the large-capacitance capacitor is increased above a predetermined voltage by the regeneration power, and driving the motor with only the charge stored in the large-capacitance capacitor, when the voltage of the large-capacitance capacitor is at least a second voltage.

In embodiments of the present invention, an energy extractor includes a capacitor which experiences capacitance and voltage changes in response to movement of a capacitor plate or of a dielectric material. In one embodiment, a third plate is positioned between first and second plates to create two capacitors of varying capacitances. In another embodiment, one capacitor plate is attached by flexible arms which permit movement across another capacitor plate. The above capacitors can be used singularly or with one or more other capacitors and are rectified either individually or in a cascaded arrangement for supplying power to a rechargeable energy source. The above capacitors can be fabricated on a substrate along with supporting electronics such as diodes.