3320 (1)
DESCRIPTION
33322220000TRANSCRIPT
Compact fluorescent lamps
Presented by
K.K.CHAITHANYA
(13761A0227)
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
2
3
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
4
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
5
Components and Assembly
6
CFL Operation
7
Electronic Ballast Block DiagramBlocks circuit-generated noise
AC-to-DC Conversion
DC-to-AC Conversion
Ignite and Run the Lamp
Feedback circuit to control lamp current
8
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)
9
AC-toDC Conversion
Generate High-Frequency 50% duty-cycle AC Square Wave
Resonant tank circuit filters square wave to a sinusoid and drives lamp
10
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
11
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
12
13
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
14
IRS2530D Dimming Control Method
15
Combine AC Lamp Current measurement with a
DC reference voltage at a single node
16
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
17
3-Way Dimming for CFL
18
3-Way Socket
19
EMI Filter
20
Rectifier and Voltage Doubler
21
Control Circuit and Half-Bridge Inverter
22
Resonant Tank
23
Lamp-Current Sensing and Feedback
24
Three-Way Interface Circuit
25
Lamp Voltage and Current (Maximum)
26
Lamp Voltage and Current (Medium)
27
Lamp Voltage and Current (Minimum)
28
Maximum: 43kHz, 240mA Medium: 62kHz, 94mA
Minimum: 67kHz, 31mA
THANK YOU
29