Electrical system using high frequency AC and having inductively connected loads, and related power supplies and luminaires
Electrical systems are provided which include a power distribution system for distributing high frequency AC power having a twisted pair conductor and power tapping element, for instance to an LED or OLED load. The electrical systems include an LED or OLED luminaire having a heat sink and a light diffusing optical element and power supplies for powering LEDs or OLEDs such as those used in the luminaire.
1. A power distribution system for distributing high frequency AC power from a current limited power source, the system comprising:
a twisted pair of elongate conductors configured to be connected to the power source, the ends of the conductors furthest from the power source being connected to one another, wherein the conductors between adjacent turns of the twisted pair are moveable apart from one another to define an aperture there between,
a power tapping element which is configured to be inserted at least partly through the aperture so that high frequency electrical power can be coupled inductively from the conductors to the power tapping element,
a further conductor wound at least partly around the power tapping element so that the high frequency electrical power can be coupled inductively from the power tapping element to the further conductor,
a synchronous rectification circuit connected to the further conductor to convert high frequency AC power in the further conductor to a DC power to power a load, and
a rectifier in the synchronous rectification circuit to controllably short circuit the further conductor to stop or vary power being transmitted to the load by controlling a switch using a signal other than the high frequency electrical power coupled inductively from the power tapping element to the further conductor.
2. The power distribution system according to claim 1 , wherein the power tapping element is a splittable ferrite member.
3. The power distribution system according to claim 1 , wherein the power tapping element comprises two spaced apart ferrite members.
4. The power distribution system according to claim 3 , wherein one ferrite member is configured to be inserted at least partly through the aperture in the twisted pair and the other ferrite member is configured to be inserted at least partly through a second aperture in the twisted pair.
5. The power distribution system according to claim 1 , wherein the load is an LED.
6. The power distribution system according to claim 1 , wherein switching of the rectifier to controllably short circuit the rectification circuit is powered by power from the twisted pair.
7. The power distribution system according to claim 1 , wherein the system incorporates a pulse density modulation arrangement to modulate power output from the system.
8. The power distribution system according to claim 1 , wherein the system incorporates a plurality of power tapping elements which are each configured to attach to the twisted pair to tap power from the twisted pair.
9. The power distribution system according to claim 1 , wherein the system further comprises a current limited high frequency AC power source which is connected to the twisted pair.
10. The power distribution system according to claim 9 , wherein the power source is configured to convert mains power to high frequency AC power.