ECE 442 Power Electronics1 Compact Fluorescent Lamps (CFLs) Advantages over incandescent lamps –Energy savings –Longer lifetime Disadvantages over incandescent lamps –Higher initial cost –Not as easy to have 3-way control (dimming)

ECE 442 Power Electronics2 Fluorescent vs. Incandescent Convert UV light to visible light Two-stage conversion –Electrons collide with mercury atoms, causing photons of uv light to be released –UV light converts to visible as it passes through the phosphor coating inside the glass tube Convert heat to light –Burn a filament (wire) at very high temperature

ECE 442 Power Electronics3 Fluorescent vs. Incandescent (cont.) More efficient –25% of energy consumed generates light –Lower lamp temperature –Longer life Less efficient –5% of energy consumed generates light –High filament temperature (350°F) –2,000 hour lifetime

ECE 442 Power Electronics4 Components and Assembly

ECE 442 Power Electronics5 CFL Operation

ECE 442 Power Electronics6 Electronic Ballast Block Diagram Blocks circuit- generated noise AC-to-DC Conversion DC-to-AC Conversion Ignite and Run the Lamp Feedback circuit to control lamp current

ECE 442 Power Electronics7 Lamp Requirements Current to pre-heat the filaments –Low-Frequency AC to DC Conversion (input) High Voltage for Ignition High-Frequency AC current during running –High-Frequency DC to AC conversion (output)

ECE 442 Power Electronics8 AC-toDC Conversion Generate High-Frequency 50% duty-cycle AC Square Wave Resonant tank circuit filters square wave to a sinusoid and drives lamp

ECE 442 Power Electronics9 At turn-on During pre-ignition, the resonant tank is a series LC circuit with a high Q factor Control IC sweeps the half-bridge frequency from maximum down towards the resonant frequency of the LC circuit Lamp filaments are pre-heated as the frequency decreases and the lamp voltage and load current increase

ECE 442 Power Electronics10 Lower the frequency until the lamp ignites Filaments are pre-heating To dim the lamp, increase the frequency of the half-bridge The gain of the resonant tank decreases and the lamp current increases The feedback circuit adjusts the half-bridge operating frequency

ECE 442 Power Electronics11

ECE 442 Power Electronics12 IRS2530D Dimming Control IC Supply Voltage Power and signal ground Dimming reference and AC lamp current feedback input VCO input High-side gate driver supply Half-bridge high-side gate driver output High voltage supply return and half-bridge sensing input Half-bridge low-side gate driver output

ECE 442 Power Electronics13 IRS2530D Dimming Control Method

ECE 442 Power Electronics14 Combine AC Lamp Current measurement with a DC reference voltage at a single node

ECE 442 Power Electronics15 3-Way Incandescent Lamp Dimming Filament #1 Filament #2 Common 4-Position Switch 0 – OFF, 1 – Filament #1 –LOW, 2 – Filament #2 – MED, 3 – Filaments in Parallel -- HIGH

ECE 442 Power Electronics16 3-Way Dimming for CFL

ECE 442 Power Electronics17 3-Way Socket

ECE 442 Power Electronics18 EMI Filter

ECE 442 Power Electronics19 Rectifier and Voltage Doubler

ECE 442 Power Electronics20 Control Circuit and Half-Bridge Inverter

ECE 442 Power Electronics21 Resonant Tank

ECE 442 Power Electronics22 Lamp-Current Sensing and Feedback

ECE 442 Power Electronics23 Three-Way Interface Circuit

ECE 442 Power Electronics24 Lamp Voltage and Current (Maximum)

ECE 442 Power Electronics25 Lamp Voltage and Current (Medium)

ECE 442 Power Electronics26 Lamp Voltage and Current (Minimum)

ECE 442 Power Electronics27 Maximum: 43kHz, 240mA Medium: 62kHz, 94mA Minimum: 67kHz, 31mA