BLDCvPPT课件

1、Agenda Basics of a BLDC Motor Topology BLDC Motor with Hall Sensors BLDC Motor with Hardware BEMF-Detection BLDC Motor Sensor less Control Switching Pattern for Driving a BLDC How to use the CAPCOM6E for a BLDC Introduction CAPCOM6E for BLDC purpose CAPCOM6E & ADC第1页/共55页Electrical Motor TypesEl

2、ectricMotor typesACAsynchronousSynchronousInductionStepperSynchronousPMSMSwitched Rel.DC第2页/共55页BLDCBasics 第3页/共55页Basics of a BLDC Motor DC Motor with 3 Brushes VWUUVW+-q 3-Phase Brush-less DC MotorAccording to the theory of DC machine, the motor rotational speed can be written as follows:N = ( Ud

3、- I R ) / (Ke )While,“N” stands for the motor rotational speed“Ud” stands for the DC voltage applied to the motor windings“R” is the pure resistance of the winding while “I” stands for the winding current “Ke” is the magnet coefficient while “ ” stands for the motor magnetic flux From the above form

4、ula, there are two methods to change the speed of DC motor: One is to change the DC voltage of the motor windings (Ud), the other one is to change the magnetic flux of the motor (). As the BLDC motor has permanent magnet rotor, only the first method can be used in practical application. The principa

5、l of generating variable DC voltage is to use PWM for chopping: change the duty cycle of the PWM voltage, proportionally change the DC voltage. NS第4页/共55页How an Inverter Turns a BLDC (1)第5页/共55页How an Inverter Turns a BLDC (2)第6页/共55页How an Inverter Turns a BLDC (3)第7页/共55页How an Inverter Turns a BL

6、DC (4)第8页/共55页How an Inverter Turns a BLDC (5)第9页/共55页How an Inverter Turns a BLDC (6)第10页/共55页BLDC with Hall Sensors Switching Patternq Typical Switching Pattern for a BLDC Hall Sequence depends on motor construction Output pattern levels depends on inverter topology第11页/共55页BLDC withHall Sensors第1

7、2页/共55页BLDC with Hall Sensors - Topologyq Typical Circuit Block Diagram Hall Sensors detect the position Over current protection and control via ADC第13页/共55页Block Diagram CAPCOM6E for BLDC Usage第14页/共55页Hardware NoiseSuppressionch0 gets capturedvalue for act. speedch1 comparefor phase delaych2 compa

8、refor timeoutCC6xact. speedCC60phase delayCC61timeoutCC62COUT6y110001CCPOS2CCPOS0111000CCPOS1001111CaptureEventResets T12Usage of CAPCOM6E to Control a BLDC (1)q BEMF-Detection/Hall SignalsHW-noise filter on CCPOSx inputs (BEMF-signals)第15页/共55页Hardware NoiseSuppressionch0 gets capturedvalue for act

9、. speedch1 comparefor phase delaych2 comparefor timeoutCC6xact. speedCC60phase delayCC61timeoutCC62COUT6y110001CCPOS2CCPOS0111000CCPOS1001111CaptureEventResets T12Usage of CAPCOM6E to Control a BLDC (2)q BEMF-Detection/Hall SignalsHW-noise filter on CCPOSx inputs (BEMF-signals)automatic reset of T12

10、 with interruptactual speed by capture ch0第16页/共55页Hardware NoiseSuppressionch0 gets capturedvalue for act. speedch1 comparefor phase delaych2 comparefor timeoutCC6xact. speedCC60phase delayCC61timeoutCC62COUT6y110001CCPOS2CCPOS0111000CCPOS1001111CaptureEventResets T12Usage of CAPCOM6E to Control a

11、BLDC (3)q BEMF-Detection/Hall SignalsHW-noise filter on CCPOSx inputs (BEMF-signals)automatic reset of T12 with interruptactual speed by capture ch0phase delay function on ch1第17页/共55页Hardware NoiseSuppressionch0 gets capturedvalue for act. speedch1 comparefor phase delaych2 comparefor timeoutCC6xac

12、t. speedCC60phase delayCC61timeoutCC62COUT6y110001CCPOS2CCPOS0111000CCPOS1001111CaptureEventResets T12Usage of CAPCOM6E to Control a BLDC (4)q BEMF-Detection/Hall SignalsHW-noise filter on CCPOSx inputs (BEMF-signals)automatic reset of T12 with interruptactual speed by capture ch0phase delay functio

13、n on ch1time out function on ch2第18页/共55页Usage of CAPCOM6E Hall Sensor Mode (1)CCPOSx Inputsfor Hallsensor Interface q MCMOUTSH / MCMOUTSL SW programmable state machine第19页/共55页Usage of CAPCOM6E Hall Sensor Mode (2)CCPOSx Inputsedge detection triggers Dead Time Counter q MCMOUTSH / MCMOUTSL compare

14、CCPOSx level with programmed value 第20页/共55页Usage of CAPCOM6E Hall Sensor Mode (2)q CCPOSx Inputsq MCMOUTSH / MCMOUTSL switch to next state on valid edge by hardware 第21页/共55页Usage of CAPCOM6E Hall Sensor Mode (3)q CCPOSx Inputs wait on edgeq MCMOUTSH / MCMOUTSL prepare next state by software 第22页/共

15、55页Usage of CAPCOM6E Modulation Control (some Choices)第23页/共55页Usage of CAPCOM6E Generate the PWM Pattern for BLDC第24页/共55页Usage of CAPCOM6E Generate the PWM Pattern for BLDC第25页/共55页Usage of CAPCOM6E Generate the PWM Pattern for BLDC第26页/共55页Usage of CAPCOM6E Generate the PWM Pattern for BLDC第27页/共

16、55页Usage of CAPCOM6E Generate the PWM Pattern for BLDC第28页/共55页Usage of CAPCOM6E Generate the PWM Pattern for BLDC第29页/共55页Usage of CAPCOM6E Modulation and Synchronization第30页/共55页Usage of CAPCOM6E Modulation and Synchronization第31页/共55页Usage of CAPCOM6E Modulation and Synchronization第32页/共55页Usage

17、of CAPCOM6E Modulation and Synchronization第33页/共55页Usage of CAPCOM6E to Control a BLDC (5)第34页/共55页Usage of CAPCOM6E to Control a BLDC (6)第35页/共55页Usage of CAPCOM6E to Control a BLDC (7)第36页/共55页Usage of CAPCOM6E to Control a BLDC (8)第37页/共55页BLDCSensor less第38页/共55页BLDC in Theory Back Electro Magne

18、tic Force Theory UP = (R x i) + (L x di/dt) + eP whereUP stands for phase voltageR stands for winding resistancei stands for actual phase currentL stands for phase inductancedi/dtstands for changment of phase current over timeePstands for electromagnetic voltage caused by magnet whilei = 0 and di/dt

19、 = 0:UP = eP by measuring UPa position detectionis possible第39页/共55页BLDC in Reality (1) BEMF vs. Currentq Real BEMF Voltage and Current: shape depends on magnets, motor speed, voltage第40页/共55页BLDC in Reality (2a) BEMF vs. Currentq Zoom In: BEMF is only visible at active switching PhaseCurrentBEMFVol

20、tage第41页/共55页BLDC in Reality (2b) BEMF vs. Currentq Current Commutation in a Coil Freewheeling diode conductsPhaseCurrentBEMFVoltage第42页/共55页BLDC in Reality (3) All Important SignalsPhaseCurrentBEMFVoltage第43页/共55页BLDC Sensor less with Hardware BEMF-Detectionq Typical Circuit Block Diagram Comparato

21、rs and RC-Filter detect the BEMF zero crossing for position detection第44页/共55页BLDC Sensor less Using ADCq Typical Circuit Block DiagramUse simple resistor divider and ADC for position detection第45页/共55页CAPCOM6E & ADCq Synchronize ADC on T13 T13 period match can trigger the ADC equidistant sampli

22、ng of analog signals exact timing guaranteed by hardware no timing jitter due to software delays第46页/共55页CAPCOM6E & ADCq Synchronize T13 on T12 T13 performs delay for stable measurement T13 period match triggers ADCq Useful for Current Measurement E.g. induction machine第47页/共55页CAPCOM6E & AD

23、Cq T13PM triggers ADC Delay between T13PM and high voltage switching event due to driving circuitq Useful for Voltage or Current Measurement E.g. BEMF detection Sample shortly before power device is switched off (BEMF is noise free)第48页/共55页CAPCOM6E & ADCq T13PM triggers ADC Delay between T13PM

24、and high voltage switching event due to driving circuitq Useful for Voltage or Current Measurement E.g. Current in DC link path Sample shortly before power device is switched off (current is noise free)第49页/共55页BLDC Sensor less Using ADCq T13 used forModulationADC triggerq T12 used for Phase delay q

25、 Software (for 60 sector) With every T13PMthe BEMF voltage is sampled and compared to a BEMF-wave tableWhen crossing a limit the software generates a CHE-event (1)Speed reference is captured and phase delay for T12ch1 is calculatedAt T12ch1 the pattern for the next sector is switched (2)第50页/共55页BLD

26、C Sensor less with Current Controlq T13 used forModulationADC triggerq T12 used for Phase delay q Software (for 60 sector) With every T13PM the ADC alternatively samplesBEMF voltagePhase currentThe current set value can be controlled by adjusting the PWM duty cycle第51页/共55页BLDC Sensor less Scope Sho

27、tsPort pin toggles when BEMF is below limitBEMFVoltagePhaseCurrent第52页/共55页q Application: Line powered Industrial Drives Power: 750 W Current: max. 5 A AC Input Voltage: 110 to 264 VACq Features: 8-bit MCU: C868 with on-chip 8 kB SRAM, with 8-bit ADC and powerful PWM module CoolSet: TDA61831G instea

28、d of a transformer for 12V supply 6 rugged IGBT DuoPacks EEPROM: 8 kB to store program + stand alone boot option Optically Isolated Serial Interface to PC for SW development + boot from PC option Protection: shut down protection for over current and over temperature Extension for alternative MCU like XC164 or TC1775 SW environment: Keil Compiler + Debugger or Mini Debugger (free software) Board c