Sinewave dimmer control method - US Patent 7019469 Description. Inventors Assignee Electronic Theatre Controls, Inc. Application No. 10971682 filed on 10/21/2004 US Classes: 315/307, Automatic regulation315/287, Periodic-type current and/or voltage regulator in the supply circuit315/209RPERIODIC SWITCH IN THE SUPPLY CIRCUIT Examiners Primary: Vu, David Attorney, Agent or Firm International Class Description The present invention relates to a method for controlling a sinewave dimmer in order to achieve reliable operation and efficient power transfer through an inductive dimmer output filter.
A lamp may be provided with power by a dimmer so that the lamp can be operated at variable, selected light intensity levels. With a phase angle dimmer, the abrupt low frequency switching during the half cycles of the power supply and resultant abrupt amplitude changes in the current supplied to a luminaire can cause problems of electrical noise and mechanical filament noise, requiring extensive filtering.
Asynchronous sinewave dimmers are well known. U.S. Listen to the cloud. Jon found some examples of light dimmers constructed using FETs and IGBTs. He was intrigued by these dimmers because they apparently had no filter inductor like triac based dimmers. That inductor can be quite large for higher amperage and make small/compact layout difficult. Also, these dimmers could be triggered at any point in the AC cycle which means they can be switched at points where the EMI can be minimized.
Triac based dimmers work by 'squelching' the current through the load at the zero crossing point and then turning on the current later in the half-cycle. To avoid these problems (noise, space), designers have turned to IGBTs and FETs. Of course, FETs and IGBTs are unidirectional. The full wave rectifier does present a problem, however. Here is a schematic for what Jon and I call an 'outside power supply IGBT dimmer'. We are using the IRG4BC20S IGBT in this example.
Below is a picture of the simulation output. Here is the new schematic. Schematics. TheSilence of the Lamps: The New Wave in Dimming. It's had a good run, but its days are numbered. The reign of conventional SCR dimmers will soon be coming to an end, and the hottest candidate for the throne is the sine wave dimmer. SCR dimming has been around since the early 1960s and came into full force a decade later as the technology became better understood and the components, more affordable.
Over the years, the trusty SCR dimmer has become smarter, more compact, slightly more efficient, and conversant in digital languages. Some are even clever enough to talk back to you, but the truth is, the basic operating principle has remained the same for 40 years. Properly designed SCR dimmers can provide beautifully smooth intensity control, and they are also very robust and relatively inexpensive. The resonating effects of the filament may also reduce lamp life, as the filament is stressed each half cycle when operated at a dimmed level.
Certain types of filament geometry and reflector design can also amplify lamp sing. Thread: IGBT Dimming ?? Www.etdimming.com/clientuploads/downloads/87-0539.pdf. Thread: Sine-wave Light Dimmer. Sine Wave Dimming. For a class on lighting technology, Casey wrote a report on exactly how the technology of sine wave dimming works. In the process of writing this report, Casey realized that there was little to no resources that would explain how this technology works in relatively laymen's terms (note: a laymen in this case would be a lighting designer rather then an electrical engineer. There is definitely some knowledge of electricity and theatrical dimming that is taken for granted), so after presenting the report he decided to post this report online... here. So, enjoy. Please remember who wrote it, and cite your sources appropriately. Click Here to View the Accompanying PowerPoint Presentation (Note: This must be viewed with IE) Autotransformers used resistive dimming to reduced voltage by lowering the amplitude of the Alternating Current (AC) sine wave.
Board. Sine Wave Dimming is a type of electrical dimming known to the engineering world as Pulse-Width Modulated (PWM) Dimming. How does it work?