Abstract:
A method of controlling power delivered to one or more loads in an inductive power transfer (IPT) system includes varying a frequency of a current in a primary conductive path (109), detecting the frequency in a pick-up inductively coupled with the primary conductive path (109), and controlling the power supplied to a load (207) associated with the pickup dependent on the detected frequency of the current in the primary conductive path (109). The frequency of the current is determined by is determined by either or both the load on a power supply (104) of the IPT system or the load on an electricity supply network supplying the power supply (104).
Abstract:
A magnetic flux pad for receiving or generating magnetic flux. The pad includes two pole areas (11, 12) associated with a magnetically permeable core 14. Coils 17 define the pole areas. The pad allows useable flux to be generated at a significant height above a surface of the pad.
Abstract:
An Inductive Power Transfer System pickup provides a controlled AC power supply by controlled variation of the phase angle between the pickup coil induced voltage (jwMI) and the tuning capacitor C voltage. The phase angle can be varied by maintaining the tuning capacitor C voltage substantially constant for a selected time period. Switches S1 and S2 may be used to clamp the tuning capacitor C voltage at substantially zero volts during the selected time period. Switch S1 can be operated to prevent a rise in positive voltage across the tuning capacitor, and switch S2 can be used to prevent the voltage across the tuning capacitor from going negative.
Abstract:
A system and method for providing a compact azimuth beamwidth in a wide band antenna. The system comprises a first radiating element disposed above a ground plane and one or more parasitic elements disposed proximate to and/or around the first radiating element. Each of the parasitic elements has a slot formed therein that is configured to control beamwidth across a specific frequency range. In one embodiment, the parasitic elements and the slots can be configured to control beamwidth across different frequency ranges. And in another embodiment, another parasitic element is disposed within the slots to control beamwidth across another frequency range.
Abstract:
A method is provided for controlling a resonant circuit (1) of an ICPT system. The resonant circuit has a controlled variable reactance (2), and a predetermined perturbation is introduced in the magnitude of variable reactance. The change in a property of the resonant circuit in response to the perturbation is sensed, and the variable reactance is varied to alter the resonant frequency of the circuit in response to the sensed change.
Abstract:
An arrangement for supplying a load with electrical energy from a power source comprises a textile, woven floor covering (101) with longitudinally running warp threads and transversely running weft threads, three or more current conductors (106) that are spaced apart and substantially parallel to one another being woven in either as warp threads or as weft threads, the current conductors replacing part of a filling warp, a binding warp or the weft threads during the weaving operation. The arrangement also comprises a feed for the connection of the current conductors (106) to the power source and a coupling device (130) for picking up electrical energy from the current conductors (106) in the floor covering (101) and transporting it further to the load when the coupling device (130) is brought into a power pick-up area of the floor covering (101). The coupling device (130) is formed in particular in such a way that electrical energy can be inductively picked up from the current conductors (106) running in the floor covering. The supply arrangement allows a high degree of flexibility and can be integrated well in rooms.
Abstract:
Power taken inductively from the alternating current in a track is received by a resonant circuit which is at least partially decoupled by a switching circuit asynchronously with the frequency of the power supply. The switch on and off time is controlled to regulate the output power, either the voltage or the current output being a function of the switch off time divided by the switch on time.
Abstract:
Secondary resonant pickup coils (102) used in loosely coupled inductive power transfer systems, with resonating capacitors (902) have high Q and could support large circulating currents which may destroy components. A current limit or “safety valve” uses an inductor designed to enter saturation at predetermined resonating currents somewhat above normal working levels. Saturation is immediate and passive. The constant-current characteristic of a loosely coupled, controlled pickup means that if the saturable section is shared by coupling flux and by leakage flux, then on saturation the current source is terminated in the saturated inductor, and little detuning from resonance occurs. Alternatively an external saturable inductor (1101, 1102) may be introduced within the resonant circuit (102 and 902), to detune the circuit away from the system frequency. Alternatively DC current may be passed through a winding to increase saturation of a saturable part of a core. As a result, a fail-safe pickup offering a voltage-limited constant-current output is provided.
Abstract:
An inductively powered lamp unit 806 is fixed onto a substrate and over a position where a primary inductive loop 803 is spread apart (as at 807). At such sites, a horizontal (or at least parallel to the surface of the substrate) component of alternating magnetic flux is available. The conductors of the loop 802-803 can be inserted in a slit 804 cut into the substrate. The spreading apart of the conductors may be ensured with a spreader 808. A power supply 801 may be a resonant supply operating at 40 kHz. The lamp unit 806 does use a resonant pickup coil which can be shorted so as to minimize coupling, and provide supply regulation. The lamp unit can be controlled by signals transmitted over the primary loop. Applications include roadway markers and fire escape egress indicators, and underwater lighting.
Abstract:
An inductive power transfer system (IPT) pick-up comprises: a pick-up coil capable of generating a voltage by magnetic induction from a primary conductive pathway, and a tuning capacitor associated with the pick-up coil to provide a first pick-up resonant circuit; a first output associated with a first control means to substantially control the voltage or current provided by the first output; a further resonant circuit connected in series or parallel with the first pick-up resonant circuit; and a second output associated with a second control means to control the voltage or current provided by the second output and a method of providing an additional independently controllable output from an IPT pick-up having a resonant pick-up circuit is also disclosed.