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Power-line Step-dimmable Lighting System Disclosure Number: IPCOM000189351D
Publication Date: 2009-Nov-06
Document File: 8 page(s) / 403K

Publishing Venue

The Prior Art Database



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Power Line Step-Dimmable Lighting System

The cost of the electricity energy production varies at different times of the day. And the cost reaches

its maximum during the peak load demand periods. As a major contributor to the load demand, lighting

loads need to be managed intelligently, by stepping down to lower light levels, during these peak load

hours. Again, during the off-business hours, there is a need to save energy by lowering the light level of

the system. Therefore, a multi-level lighting system, similar to bi-level step dimming is highly essential.

This will not only reduce the cost incurred by the customer, but also would significantly reduce the load

demand for the generating systems.

A major disadvantage of the conventional step-dim ballast is the presence of additional wire as

compared to the non-dimming standard ballasts. For light level reduction to actuate energy savings, the

whole system of ballasts needs to be re-wired. This makes it really difficult in retro-fitting, i.e. replacing

the standard ballasts with step-dimmable ballasts. FIG 1 shows the block diagram of the conventional

step-dimming system.

Secondly, the conventional step-dimming uses two separate switches S1 (to turn ON/OFF power), and

S2 (enable/disable step-dimming).

S1 S2

FIG 1: Block Diagram of the conventional three-wire step-dimming interface






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The proposed novel design of the power-line step-dimming system solves these issues, by eliminating

the need additional wires, and provides a cheap solution for huge cost savings by light level reduction.

The power-line step-dimming system consists of a power-line step-dimmer switch, and a driver interface

for decoding the dimming signal from the power line. FIG 2 shows the block diagram of the proposed

step-dimming system.

The power-line step-dimmer switch consists of a three- position switch, and the step-dim signal injector.

The three-position switch can enable step-dimming signal injector to lower the light level, bypass the

signal injector to achieve full light output, or turn OFF the power.







Step-dim Signal Injection


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FIG 2: Block diagram of the power-line step-dimming system

The step-dimmer switch when enabled, injects a signal of fixed time interval near the zero crossing of

the line current. FIG 3 shows the possible different type of signals injected at the zero crossing of the

line current. The signal injection at the zero crossing does not impact the THD of the line current.

The output of this step-dimmer can be used to power a number of step-dimmable electronic drivers; the

maximum possible number of the electronic driver depends on the total power drawn by the drivers.

The electronic driver interface circ...