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Freescale Semiconductor M68HC08 Light Ballast Control, Power Factor Correction, Control Board

Models: M68HC08

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CONTROL BOARD

Application Description

MAINS

FILTER

ZERO CROSSING

CONTROL BOARD

UREQ

USER INTERFACE

RECTIFIER

VOLTAGE

BUS-

DC

-

DC-BUS

PFC

DRIVER

POWER

SUPPLY

	PWM
ACTUAL CURRENT
FILTER
PWM	+ -
GENERATION

HALF BRIDGE

DRIVER

PWM

HIGH

RESOLUTION

PWM

RESONANT

CIRCUIT

DIFFERENTIAL

VOLTAGE

CURRENT	CURRENT
1	2

FLUORESCENT LAMPS

MONITOR MODE

LUMINANCE LEVEL

e	sineGain
	PI
	REGULATOR
	ireq	e
BRIGHTNESS	ireq	-

LINEARIZATION

MC68HC908LB8

fHRP

PI

REGULATOR

iact

TUBE

TUBE

CURRENT

PROCESSING e

Figure 3-1. Dimmable Light Ballast — System Concept

3.3.1 Light Ballast Control

The HRP provides two complementary PWM outputs for controlling a half-bridge in a light ballast application. It uses a dithering control method to provide a high step resolution (3.9 ns) from an 8 MHz input clock when driving inductive loads.

The High Resolution PWM Module (HRP) uses a dithering technique to increase the resolution of the output signal.The output switches between two frequencies or duty cycles at a programmable rate. By varying the percentage of time spent on each frequency/duty cycle, the output will appear to be at a value between the two dithering frequencies/duty cycles when driving an inductive load.

The advantage is easy implementation of a control method for half-bridge inverter using few external devices. The main advantage is simple performance using few instructions to perform the dithering control algorithm.

3.3.2 Power Factor Correction

The power factor correction circuitry provides the “sinusoidal” input current by controlling the PFC switch. In the control loop, the actual DC-bus voltage is compared with the desired one. The control error is processed by the PI (proportional-integral) controller, which generates the amplitude of the input “sinusoidal” current. The PWM generator generates the desired sinusoidal current profile using a PWM technique. The digital output signal is filtered by a passive filter and the resulting analog waveform is compared with the actual input current by an on-chip comparator. The comparator output controls directly

Dimmable Light Ballast with Power Factor Correction, Rev. 1

Freescale Semiconductor

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Freescale Semiconductor M68HC08 manual Light Ballast Control, Power Factor Correction, Control Board, MC68HC908LB8

Contents

DRM067 Rev. 1 12/2005 Designer Reference ManualM68HC08 Microcontrollers Page Designer Reference Manual Freescale Semiconductor Draft 2 for ReviewChapter Hardware Design Contents Chapter IntroductionChapter Control Theory Chapter Reference DesignAppendix B. References Chapter Demo SetupAppendix A. Schematics and Part List Chapter Software Design1.1 Introduction 1.2 Benefits of this SolutionChapter Introduction 1.3 The MC68HC908LB8 Microcontroller 7-bitkeyboard interrupt Freescale Semiconductor Introduction2.1.2 Fluorescent Lamp Operation Chapter Control Theory2.1 Introduction 2.1.1 Fluorescent Lamp Control TheoryGas filling mixture Freescale Semiconductor 2.1.3 Controlling the Fluorescent LampFreescale Semiconductor 2.2.1 Introduction 2.2PFC Control TheoryFreescale Semiconductor Freescale Semiconductor Zero MCU PWM PWM1 FAULT PINControl Theory DC Bus VoltageFigure 2-8.Generated Input Current Waveform 2.2.4 Concept SummaryFreescale Semiconductor Control Theory3.1 Application Outline 3.2 Dimmable Light Ballast CharacteristicsChapter Reference Design Table 3-1.Light Ballast Characteristics 3.3 Application DescriptionMC68HC908LB8 3.3.2 Power Factor Correction3.3.1 Light Ballast Control CONTROL BOARD3.3.3 Protection Features 3.4 Software Specification3.5 Hardware Specification 4.2 System Modules Chapter Hardware Design4.1 Hardware Implementation Hardware Design 4.2.1 Input and PFCFigure 4-3.Dimmable Light Ballast - Input and PFC Freescale Semiconductor 4.2.2 InverterHALF BRIDGE Figure 4-4.Dimmable Light Ballast - InverterSystem Modules Freescale Semiconductor4.2.3 Microcontroller TOP BOT Comp Comp Out Zero Detect SignalSystem Modules Pin numberPin number SignalTable 4-2.J2 Interface Header Hardware DesignTable 4-3.Supplied Voltages 4.2.4 Power SupplyFigure 4-6.Dimmable Light Ballast - Power Supply Freescale Semiconductor Hardware Design5.2 Control Algorithm Description Chapter Software Design5.1 Introduction 5.2.1.1 DC-busVoltage Control 5.2.1 Power Factor Correction Control5.2.1.2 Phase Shift Synchronization 5.2.1.4 Generation of Output PFC Control SIgnal5.2.2.2 Luminance Level Control Tube Run Mode 5.2.2 Light Ballast Control5.2.2.1 Tube Start Mode rounditmax ⋅ ADmax ⁄ imax q = itADmin - A ⋅ ek ⋅ ADminireq = A ⋅ ek ⋅ ireqAD + q rounditmin ⋅ ADmax ⁄ imax5.3 Software Implementation 5.3.1 Initialization Setup5.3.1.1 PWM Setup Hz Hz 5.3.1.2 HRP SetupPWM Frequency = BusFrequency5.3.2 Main Program Loop Freescale Semiconductor 5.3.3 Synchronization Interrupt Routine5.3.4 Sine Wave Generation Interrupt Routine Read new PWM value from table * sineGain Set 1ms flag and reset 1ms counterSoftware Design interrupt void pwmISRvoid5.3.4.1 Fault Detection and Processing Stop HRP 5.4 Detailed Software DescriptionFigure 5-6.Flow Chart - timovISR and faultISR Software DesignDetailed Software Description Figure 5-7.Flow Chart - Main Flow, PartFreescale Semiconductor Figure 5-8.Flow Chart - Main Flow, PartSoftware Design Freescale Semiconductor Figure 5-9.Flow Chart - Main Flow, PartDetailed Software Description Freescale Semiconductor Figure 5-10.Flow Chart - Main Flow, PartSoftware Design 5.5.1 Microcontroller Peripheral Usage 5.5.1.1 High Resolution PWM HRP5.5.1.4 Timer Interface Module TIM 5.5 Microcontroller UsageI/O pin 5.6 Definitions of Constants and Variables5.5.3 I/O Usage Software Design5.6.1 System Setup Definitions defines the minimum HRP frequency in kHz 5.6.2 System Constants and Variables Page 6.2.1 Required Software Tools Chapter Demo Setup6.1 Hardware Setup 6.2 Software Setup\Sources\pi controller.c, PI regulators file 6.2.3 Executing the Application6.2.4 Project Files \prm\P&E FCS linker.prm, linker program fileA.1 Schematics Appendix A. Schematics and Part ListPFC Gate 2.7mHPFC Current Sense CompZero Detect PFC Current SenseComp PFC GateCOM LO Figure A-3.InverterDCB TOP BOT O1 O2 O3 O4 O5 O6 O7 O8Tube Voltage difference TOP BOT Comp - Comp Out Zero DetectSerial Data Serial Data DCB Divider Tube Current Tube CurrentTube Voltage difference GNDSerial Data5 Serial Data DCB Divider Tube Current Tube CurrentFigure A-6.Power supply DESCRIPTION A.2 Parts ListDESIGNATORS QUANTITYMANUFACTURER DESIGNATORSQUANTITY DESCRIPTIONFreescale Semiconductor Appendix B. References Freescale Semiconductor Page USA/Europe or Locations Not Listed How to Reach UsHome Page E-mail