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Compact Fluorescent Lamps (CFLs)

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). Convert UV light to visible light Two-stage conversion

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Compact Fluorescent Lamps (CFLs)

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  1. 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 Electronics

  2. 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 Fluorescent vs. Incandescent ECE 442 Power Electronics

  3. 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 Fluorescent vs. Incandescent (cont.) ECE 442 Power Electronics

  4. Components and Assembly ECE 442 Power Electronics

  5. CFL Operation ECE 442 Power Electronics

  6. 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 Electronics

  7. 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 Electronics

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

  9. 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 Electronics

  10. 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 Electronics

  11. ECE 442 Power Electronics

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

  13. IRS2530D Dimming Control Method ECE 442 Power Electronics

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

  15. 3-Way Incandescent Lamp Dimming Filament #1 4-Position Switch Filament #2 Common 0 – OFF, 1 – Filament #1 –LOW, 2 – Filament #2 – MED, 3 – Filaments in Parallel -- HIGH ECE 442 Power Electronics

  16. 3-Way Dimming for CFL ECE 442 Power Electronics

  17. 3-Way Socket ECE 442 Power Electronics

  18. EMI Filter ECE 442 Power Electronics

  19. Rectifier and Voltage Doubler ECE 442 Power Electronics

  20. Control Circuit and Half-Bridge Inverter ECE 442 Power Electronics

  21. Resonant Tank ECE 442 Power Electronics

  22. Lamp-Current Sensing and Feedback ECE 442 Power Electronics

  23. Three-Way Interface Circuit ECE 442 Power Electronics

  24. Lamp Voltage and Current (Maximum) ECE 442 Power Electronics

  25. Lamp Voltage and Current (Medium) ECE 442 Power Electronics

  26. Lamp Voltage and Current (Minimum) ECE 442 Power Electronics

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

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