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Motorola M68HC08 manual Back-EMF at Start Up

Models: M68HC08

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Freescale Semiconductor, Inc.

Freescale Semiconductor, Inc.

BLDC Motor Control

Figure 3-19demonstrates the back-EMF during the start up. The amplitude of the back-EMF varies according to the rotor speed. During the starting (back-EMF acquisition) state the commutation is done in advance. In the running state the commutation is done at the right moments.

PHASE BACK-EMFS

PHASE C

PHASE A

PHASE B

BACK-EMF ZERO CROSSINGS

IDEAL COMMUTATION PATTERN WHEN POSITION IS KNOWN

BTOP

CTOP

ATOP

BTOP

CTOP

CBOT

ABOT

BBOT

CBOT

ABOT

REAL COMMUTATION PATTERN WHEN POSITION IS ESTIMATED

BTOP

CTOP

ATOP

BTOP

CTOP

ABOT

BBOT

CBOT

ABOT

CBOT

FIRST

SECOND

THIRD

FOURTH

.................

ALIGN

STARTING (BACK-EMF ACQUISITION)

RUNNING

Figure 3-19. Back-EMF at Start Up

Figure 3-20illustrates the sequence of the commutations during the starting (back-EMF acquisition) state. The commutation times T2[1] and T2[2] are calculated without any influence of back-EMF feedback. The commutation time calculations are explained in the following section.

Designer Reference Manual		DRM028 — Rev 0

48	BLDC Motor Control	MOTOROLA
	For More Information On This Product,
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Motorola M68HC08 manual Back-EMF at Start Up

Contents

M68HC08 Freescale Semiconductor, IncFor More Information On This Product Sensorless Bldc Motor Control Using MC68HC908MR32 Designer Reference Manual RevRevision history List of Sections List of Sections Table of Contents Table of Contents List of Figures TitleList of Figures List of Tables List of Tables Contents Benefits of the SolutionIntroduction Application FunctionalityIntroduction System Description System ConceptSystem Description System Specification Software Specification Software written in C language specifications are listedSoftware parameter tuning to a customer motor Software SpecificationsHardware and Drive Specifications High-Voltage Hardware Set SpecificationHigh Voltage Hardware Set Specifications Motor -Brake SetLow-Voltage Evaluation Hardware Set Specification Low Voltage Evaluation Hardware Set SpecificationsLow-Voltage Hardware Set Specification Low Voltage Hardware Set Specifications Bldc Motor Control Brushless DC Motor Control TheoryBldc Motor Targeted by This Application Semiconductor, Inc Bldc Motor Control Brushless DC Motor Control Theory Bldc Motor Back EMF and Magnetic Flux 2 3-Phase Bldc Power Stage Why Sensorless Control?Power Stage Motor Topology Stator Winding Equations Indirect Back EMF SensingSame expressions can also be found for phase a and B Phase Voltage Waveform Effect of Mutual InductanceMutual Inductance Effect Effect of Mutual Phase Capacitance Detail of Mutual Inductance EffectMutual Capacitance Model 10. Distributed Back-EMF by Unbalanced Capacity Coupling 11. Balanced Capacity Coupling Back-EMF Sensing Circuit Inc Used Control Technique Sensorless Commutation ControlAlignment Starting Back-EMF Acquisition Running 14. Commutation Control Stages Alignment15. Alignment RunningFreescale Semiconductor, Inc Running Commutation Time Calculation Commutation time calculation is shown in FigureService of received back-EMF zero crossing 17. Bldc Commutation Time with Zero Crossing SensingWhere Starting Back-EMF Acquisition Freescale Semiconductor, Inc 18. Vectors of Magnetic Fields 19. Back-EMF at Start Up Starting Commutation Time Calculation Running Commutation Time Calculation, but the followingComputation coefficients are different Application Control Speed ControlPC Master Software Communication with PC Master Software Specifications PC Master Software Communication CommandsPC Master Software API Variables Name Type Representing Description RangeMotorStatusDef, FailureDef BIT6 ReservedBIT2 Reserved PerSpeedMAXRange and zero crossing period PerZCrosFltT2 SpeedRangeMaxRPM*PerSpeedMAXRange/PerZCrosFltT2Freescale Semiconductor, Inc System Configuration and Documentation Hardware DesignMC68HC908MR32 Control Board For High-Voltage Hardware Set cofigurationFor Low-Voltage Evaluation Motor Hardware Set configuration EVM Motor Board Phase Low Voltage EVM Bldc MotorLow-Voltage Hardware Set configuration Components will describe the individual boardsHigh-Voltage Hardware Set Configuration High-Voltage Hardware System ConfigurationDescribed in MC68HC908MR32 Control Board User’s Manual Motorola document order numberSee References Low-Voltage Evaluation Motor Hardware Set Configuration Low-Voltage Evaluation Motor Hardware System ConfigurationLow-Voltage Hardware Set Configuration System configuration for low-voltage hardware set is shownLow-Voltage Hardware System Configuration All HW Sets Components References1 MC68HC908MR32 Control Board 4shows a block diagram of the board’s circuitry Electrical characteristics in -1apply to operation at 25CElectrical Characteristics of Control Board 1 3-Phase AC/BLDC High Voltage Power StageHigh-Voltage Hardware Set Components Phase AC High Voltage Power Stage Electrical Characteristics of Power Stage Optoisolation BoardElectrical Characteristics of the Optoisolation Board Electrical Characteristics3 3-phase Bldc High Voltage Motor with Motor Brake Low-Voltage Evaluation Motor Hardware Set ComponentsEVM Motor Board Electrical Characteristics of the EVM Motor Board Electrical Characteristics of the EVM Motor Board2 3-phase Low Voltage EVM Bldc Motor Characteristics of the Bldc motor1 3-Ph AC/BLDC Low Voltage Power Stage Low-Voltage Hardware Set ComponentsBlock Diagram 2 3-phase Bldc Low Voltage Motor with Motor Brake SectionData Flow Main Software Flowchart State Diagram Software DesignIntroduction Data FlowSoftware Variables and Defined Constants Important system variables are listed in TableSoftware Variables Start/Stop Switch Reading and Start/Stop Decision Sys3DefProcess Measurement Main Data Flow Part1 Process Fault Control Fault Stop Process Back, EMF Zero Crossing SensingFreescale Semiconductor, Inc Main Data Flow Part 2 Alignment, Starting Process Desired Speed Setting Closed Loop Control SystemProcesses Commutation and Zero Crossing Preset and Set Bldc Speed Control and CalculationProcess Alignment Control Main Software Flowchart Bldc Commutation and Zero Crossing SelectionMain Software Flowchart Freescale Semiconductor, Inc Main Software Flowchart Main Software Loop Freescale Semiconductor, Inc Freescale Semiconductor, Inc State Diagram Software Flowchart InterruptsApplication State Transitions State diagram for this software is shown in Figure Initialize MCUInitialize Application Stand-ByFreescale Semiconductor, Inc Stand-by State Align State Starting Commutation Time Calculation Freescale Semiconductor, Inc 10. Back-EMF Acquisition Service of Commutation SetCommutation Time Calculation Service of Received Back-EMF Zero Crossing Running StateExplained in 5.5.5 Back-EMF Acquisition State Over Current 11. Running State 12. Stop State Fault State Stop StateImplementation Notes See FigureSoftware Files Software files and structure are described in sectionPreset Bldc Commutation and Bemf Zero Crossing Selection Bldc Commutation and Zero Crossing SelectionSet Bldc Commutation and Bemf Zero Crossing Selection Bldc Speed Control and Calculation Desired Speed CalculationPWM Duty Cycle PWMValMax = DUTYPWMMAX*MCPWMMODULUSTimers TimerFunction TIMACh3Int Designer Reference Manual DRM028 Rev 108 Software Design User Guide Application Suitability GuideMinimal Application Speed Motor’s nominal speedMaximal Application Speed Voltage Closed LoopMotor Suitability Mutual Inductance Designer Reference Manual DRM028 Rev 112 User Guide Application Hardware and Software Configuration Hardware ConfigurationHardware setups are shown in -1, -2, High-Voltage Hardware Set Configuration Low-Voltage Evaluation Motor Hardware Set ConfigurationLow-Voltage Hardware Set Configuration Controller Board Settings EVM Board Settings EVM board settings are the same for all hardware platformsSoftware Setup Application HC08 Software Files \bldczerocros08MR32\sources\bldc08.c, main program Application PC Master Software Control Files Software Execution BuildExecute from Evaluation Board When the software is built, the S-record file Execute from Pre-programmed MCUBldczerocros08mr32MMDS.sx is generated Application ControlManual Operating Mode PC Master Software Remote Operating ModePC Master Software Control Window For More Information On This Product Tuning for Customer Motor User Guide Tuning for Customer Motor Follow-up for Software Customizing to Customer Motor Follow-up for Advanced Software Customizing To have PC master software installed on your PC computer Start the PC master software parameters tuning application11. PC Master Software Parameters Tuning Control Window Software Parameters Setting Follow-up Labels in the File const.h Software Customizing to Power Stage Parameters File Selection\bldczerocros08MR32\sources\constcustlv.h, definitions for Example of Software Customizing to HardwareVoltage Setting Hardware Customizing Current Setting Hardware CustomizingRange 0,infinity Example of Software Customizing to Hardware Modified maximal measurable voltage is 55 V, so setSoftware Customizing to Motor Voltage and Current Settings Maximal and Minimal Voltage Limits SettingDetailed description starts here Range 0,VOLTRANGEMAXMaximal and Minimal Current Limits Setting Range 0,CURRENTRANGEMAXAAlignment Current and Current Regulator Setting Current during alignment state before motor starts ΑRange 0,8 Parameters Tuning with PC Master Software Project File Set constcustx.hFrom Evaluation Board 12. PC Master Software Current Parameters Tuning Window Designer Reference Manual DRM028 Rev 142 User Guide MUSTCHANGEEXPERnn in file constcustx.h Commutation Parameters Commutation time period to discharge coil current ∝sStart-up Constants and Maximal Commutation Period Start-up Period Maximal commutation period limit ∝sRange -128,127 Alignment Current and Current Regulator Setting 6.5.4.3 Constcustx.hConstcustx.h Set #define Percmtstartus in constcustx.h Ensure Percmtstartus =PERCMTMAXUS /2#define Speedpiregigain Constcustx.h file13. PC Master Software Start Parameters Tuning Window Software Customizing to Motor Speed Control Setting Number of commutations per motor revolutionRange 0,255 Maximal speed range rpm Minimal speed of the drive rpmRange 0,SPEEDRANGEMAXRPM Speedminrpm = 0.07 to 0.5SPEEDMAXRPM User Guide 153 Execute from Evaluation Board Set PC master software control mode and start motor see Remote Operating ModeStart motor see Application Control and PC Master Software PWM Frequency and Current Sampling Period Setting For the PWM frequency setting, follow the labelPWM frequency setting is provided by PWM FrequencyPWM Frequency Setting PWM period = Periodpwmus = SETPERPWM*2 EQCurrent Sampling Period Conclusion Software Parameters Setting and Tuning CANCHANGEPERCURSAMPn in const.h filePERCST1US = Periodpwmus * Setpercs ∝s Current Sampling InstantUser Guide 159 Designer Reference Manual DRM028 Rev 160 User Guide Appendix A. References Motor using MC68HC705MC4 document order number AN1627, MotorolaAppendix B. Glossary SG40NGlossary Serial communications interface module SCI a module that Designer Reference Manual DRM028 Rev 166 Glossary Freescale Semiconductor, Inc HOW to Reach US USA/EUROPE/LOCATIONS not Listed