TIDUCL0 January   2017

 

  1. 1 Description
  2. 2 Resources
  3. 3 Features
  4. 4 Applications
  5. 5 Design Images
  6. 6 System Overview
    1. 6.1 System Description
    2. 6.2 Key System Specifications
    3. 6.3 Block Diagram
    4. 6.4 Highlighted Products
      1. 6.4.1 CSD88584Q5DC
      2. 6.4.2 DRV8323
      3. 6.4.3 MSP430F5132
      4. 6.4.4 TPS54061
      5. 6.4.5 LMT87
  7. 7 System Design Theory
    1. 7.1 Power Stage Design—Battery Power Input to the Board
    2. 7.2 Power Stage Design—Three-Phase Inverter
      1. 7.2.1 Design Considerations in Paralleling MOSFETs
        1. 7.2.1.1 Conduction Phase
        2. 7.2.1.2 Switching Phase
      2. 7.2.2 Selecting the Sense Resistor
    3. 7.3 Power Stage Design—DRV8323 Gate Driver
      1. 7.3.1 Gate Drive Features of DRV8323
      2. 7.3.2 Current Shunt Amplifier in DRV8323
      3. 7.3.3 Protection Features in DRV8323
    4. 7.4 Power Stage Design—18-V to 3.3-V DC-DC Converter
    5. 7.5 Power Stage Design —Microcontroller MSP430
    6. 7.6 Power Stage Design—Hall Sensor Interface
    7. 7.7 Temperature Sensing
    8. 7.8 Power Stage Design—External Interface Options and Indications
      1. 7.8.1 Speed Control of Motor
      2. 7.8.2 Direction of Rotation—Digital Input
      3. 7.8.3 LED Indications
      4. 7.8.4 Signal Interface Connector for External Monitoring and Control
  8. 8 Getting Started Hardware and Software
    1. 8.1 Hardware
      1. 8.1.1 Connector Configuration of TIDA-00774
      2. 8.1.2 Programming of MSP430
      3. 8.1.3 Procedure for Board Bring-up and Testing
    2. 8.2 Software
      1. 8.2.1 System Features
      2. 8.2.2 Customizing the Reference Code
        1. 8.2.2.1 PWM_PERIOD
        2. 8.2.2.2 MAX_DUTYCYCLE
        3. 8.2.2.3 MIN_DUTYCYCLE
        4. 8.2.2.4 ACCEL_RATE
        5. 8.2.2.5 Block_Rotor_Duration
      3. 8.2.3 Configuring the DRV8323 Registers (drv8323.c)
      4. 8.2.4 Initializing SPI Communication Between DRV8323 and MSP430 (drv8323.h)
      5. 8.2.5 Running Project in Code Composer Studio (CCS)
  9. 9 Testing and Results
    1. 9.1 Test Setup
    2. 9.2 Test Data
      1. 9.2.1 Functional Tests
        1. 9.2.1.1 3.3-V Power Supply Generated by Step-Down Converter
        2. 9.2.1.2 Gate Drive Voltage Generated by Gate Driver
        3. 9.2.1.3 Dead Time From DRV8323
        4. 9.2.1.4 MOSFET Switching Waveforms
        5. 9.2.1.5 VGS Skew of Parallel FETs During Switching
      2. 9.2.2 Load Test
        1. 9.2.2.1 Load Test Without Heat Sink
        2. 9.2.2.2 Load Test With Heat Sink
        3. 9.2.2.3 Load Test With Heat Sink and Airflow
      3. 9.2.3 Inverter Efficiency Test
      4. 9.2.4 Thermal Rise at Different Power Levels
      5. 9.2.5 Inverter Current Sensing by VDS Monitoring
      6. 9.2.6 Overcurrent and Short-Circuit Protection Test
        1. 9.2.6.1 Cycle-by-Cycle Stall Current Protection by DRV8323 VDS Sensing
        2. 9.2.6.2 Stall Current Latch Protection by DRV8323 VDS Sensing
      7. 9.2.7 Testing for Peak Current Capability
  10. 10Design Files
    1. 10.1 Schematics
    2. 10.2 Bill of Materials
    3. 10.3 PCB Layout Recommendations
      1. 10.3.1 Layout Prints
    4. 10.4 Altium Project
    5. 10.5 Gerber Files
    6. 10.6 Assembly Drawings
  11. 11Software Files
  12. 12Related Documentation
    1. 12.1 Trademarks
  13. 13Terminology
  14. 14About the Author

8.2.1 System Features

The TIDA-00774 firmware offers the following features and user controllable parameters:

  • Trapezoidal control of BLDC motor using digital position Hall sensor feedback
  • Overcurrent cycle by cycle protection and latch protection using the VDS sensing feature of DRV8323S

The TIDA-00774 firmware system components are tabulated in Table 3.

Table 3. TIDA-00774 Firmware System Components

SYSTEM COMPONENT DESCRIPTION
Development and emulation Code Composer Studio™ v5.5
Target controller MSP430F5132
PWM frequency 20-kHz PWM (default), programmable for higher and lower frequencies
PWM mode Asymmetrical
Interrupts Port 2 Interrupt for hall sensor change
CPU Timer D – Implements 20-kHz ISR execution rate
ADC interrupt
PWM generation—Timer configuration High-side PWM- TIMER TD0.1, Clock-25 MHz, OUTMOD[2:0]= 2,PWM frequency set for 20 kHz
Low-side PWM- TIMER TD0.2, Clock-25 MHz, OUTMOD[2:0]= 6,PWM frequency set for 20 kHz
Position feedback—Hall sensor signals P2.2 → HA
P2.1 → HB
P2.3 → HC
Comparator configuration for overcurrent protection CB2/P1.2 →CSA output (–ve input of comparator)
Internal VREF (+ve input of comparator)
CBOUT/P3.3 → Comparator output
PM_TEC1FLT1 → PWM shut off input
ADC channel assignment A0 → DC bus voltage sensing
A1 → Low-side DC bus current sensing/PHASE A low-side MOSFET VDS sensing
A3 → PCB or FET temperature feedback
A4 → PHASE B low-side MOSFET VDS sensing amplifier output
A5 → PHASE C low-side MOSFET VDS sensing amplifier output
A7 → Speed reference from the external potentiometer
DRV8323—SPI programming pins connection PJ.0 → SDO
PJ.1 → SDI
PJ.2 → SCLK
PJ.3 → SCS
DRV8323—Digital inputs and outputs PJ.5 → EN_GATE
PJ.4 → FAULT
P2.4 → CAL
MCU digital inputs and output P1.6 → Direction of motor rotation
P3.2 → LED3