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Digital Control HID Ballast Reference Design

Digital Control HID Ballast Reference Design. Agenda. Introduction to HID lamp and ballast Automotive headlight HID ballast design Software integration Summary. What is a HID lamp . Abbreviation for H igh I ntensity D ischarge The arc tube is filled with metal salts and halide gas

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Digital Control HID Ballast Reference Design

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  1. Digital Control HID Ballast Reference Design

  2. Agenda • Introduction to HID lamp and ballast • Automotive headlight HID ballast design • Software integration • Summary

  3. What is a HID lamp • Abbreviation for High Intensity Discharge • The arc tube is filled with metal salts and halide gas • Once excited with high voltage pulses an arc is initiated between the electrodes • The plasma arc produces visible light • There are 4 types of HID lamps, but only the Xenon HID Lamp is discussed in this design Electrode Arc Tube Electrode Bulb

  4. Why a HID Lamp • Compared to fluorescent and incandescent lamps, HID lamps present these benefits: • High system efficacy • Long life – up to 20k hrs • High lumen output and no maintenance • Good color rendition over life • Widely used in commercial, industrial, public, residential, and automotive applications

  5. HID Lamp Characteristics • Negative impedance • Lamp cannot be directly connected to power line • Current and power must be regulated

  6. HID Lamp Characteristics (Cont.) • HID lamps require a complex external drive for proper operation • Current control • Power control • Ignition • Timing control

  7. Why HID Ballast • Each HID lamp must be operated by a ballast • The ballast is specifically designed to: • Produce striking voltage to “break over” the halide gas • Provide and regulate proper voltage, current and power to sustain the arc discharge and stabilize light output • Fast start-up • To meet international regulatory standards • The ballast improves the lamp’s performance and life.

  8. Igniter Typical Automotive Headlight Ballast Block Diagram 20~400VDC Lamp Anti-Reverse Full Bridge DC/DC Battery Aux Power Comparator Driver PWM IC PWM I V MCU ADC ADC Filter PWM

  9. Agenda • Introduction to HID lamp and ballast • Automotive headlight HID ballast design • Software integration • Summary

  10. Specifications • Input voltage: 9V~16V • Steady output power: 35W ±1W • Max input power: 115W • Max output power: 85W • Time of steady light output: < 150 seconds • Efficiency: > 85% • Protection: UV, OV, OC • Dimensions: 9 mm * 60 mm * 80 mm

  11. Igniter DSC-based Automotive Headlight Ballast Block Diagram 20~400VDC Lamp Anti-Reverse DC/AC DC/DC Battery Aux Power Driver PWM IC I I/O V DSC ADC/Comparator ADC/Comparator PWM

  12. Brief Schematic DC/DC Inverter T1 Q1 Q3 Anti-Reverse Q2 Q4 Igniter 12V Opamp Driver Driver Vfd Ifd Vin AN2 PWM1H AN0/CMP1 AN1/CMP2 Aux Power 3.3V dsPIC33FJ06GS202 I/O

  13. DC/DC Stage T1 Vout Vin 12V Driver PWM

  14. DC/DC Working Profile

  15. Inverter Stage

  16. HID lamp HID lamp + - - Vbus Vbus + + D2 G1 D2 G1 + T1 - D1 D1 R R + - When Vbus < 0, Vc3 = Vbus When Vbus > 0, Vc4 = Vbus +VC3 Igniter Charge Process T1

  17. dsPIC® Digital Signal Controller

  18. Control Mode Transition Warm-Up: Current control loop Turn-On ~ Takeover stage: voltage control loop Run-Up ~ Steady Status stage: Power control loop

  19. Voltage Control Implementation

  20. Power Control Implementation

  21. Ballast Board Layout

  22. Ballast Board Layout dsPIC33FJ06GS202

  23. Ballast Board Layout dsPIC33FJ06GS202 DC/DC

  24. Ballast Board Layout dsPIC33FJ06GS202 Inverter DC/DC

  25. Ballast Board Layout Igniter dsPIC33FJ06GS202 Inverter DC/DC

  26. Lamp Start-up Voltage Voltage scale: 100V/div Current scale: 1A/div Zoom in Current Voltage Current Time scale: 2s/div (upper figure) Time scale: 10ms/div (bottom figure)

  27. Agenda • Introduction to HID lamp and ballast • Automotive headlight HID ballast design • Software integration • Summary

  28. Software Structure • Initialize PWM • Initialize Comparator • Initialize ADC • Initialize I/O Ports • Setup Timers • Configure Interrupts • Initialize Control Loop Variables Start Initialization Enable Peripherals • Enable PWM • Enable Comparator • Enable ADC

  29. Start Initialization Enable Peripherals • Check Battery voltage level • 9V > Vin < 16V Check battery voltage Software Structure

  30. Start Initialization • Voltage and Current Measurement • Detect lamp status • Execute corresponding Control Loops • Update PWM Duty Cycle Enable Peripherals Check battery voltage ADC Interrupt Software Structure

  31. Start Initialization Enable Peripherals Check battery voltage • Detect ignition failure • Generate Full Bridge PWM • Provide timer to Warm up ADCInterrupt 1 Timer2 Software Structure

  32. Agenda • Introduction to HID lamp and ballast • Automotive headlight HID ballast design • Software integration • Summary

  33. Summary • This design is a full digital control HID ballast implementation • The dsPIC device provides all of the necessary items to implement a high-performance HID ballast • High MIPs DSP+MCU core • On-chip Intelligence Power Peripherals • Fast and smooth transition between different modes • Precise timing control • System diagnose and fault • The dsPIC device simplifies the design and control of a HID Ballast • The dsPIC device represents a simple circuitry, cost, and space efficient approach

  34. Resources • Link to HID Ballast Reference Design: www.microchip.com/smps and select HID Ballast • Available for Free Download: • Application note • Complete Source code • PCB Design files • For resources and information for Switch Mode Power Supply applications, visit Microchip’s SMPS Design Center at: www.microchip.com/smps

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