TIDUBE5A January   2022  – October 2022

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
    1. 1.1 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 TMS320F2800137
      2. 2.3.2 TMS320F280025C
      3. 2.3.3 TMS320F280039C
      4. 2.3.4 UCC28740
      5. 2.3.5 UCC27517
      6. 2.3.6 TLV9062
      7. 2.3.7 TLV76733
    4. 2.4 System Design Theory
      1. 2.4.1 Interleaved PFC
        1. 2.4.1.1 Full Bridge Diode Rectifier Rating
        2. 2.4.1.2 Inductor Ratings
        3. 2.4.1.3 AC Voltage Sensing
        4. 2.4.1.4 DC Link Voltage Sensing
        5. 2.4.1.5 Bus Current Sensing
        6. 2.4.1.6 DC Link Capacitor Rating
        7. 2.4.1.7 MOSFET Ratings
        8. 2.4.1.8 Diode Ratings
      2. 2.4.2 Three-Phase PMSM Drive
        1. 2.4.2.1 Field Oriented Control of PM Synchronous Motor
        2. 2.4.2.2 Sensorless Control of PM Synchronous Motor
          1. 2.4.2.2.1 Enhanced Sliding Mode Observer with Phase Locked Loop
            1. 2.4.2.2.1.1 Mathematical Model and FOC Structure of an IPMSM
            2. 2.4.2.2.1.2 Design of ESMO for the IPMSM
            3. 2.4.2.2.1.3 Rotor Position and Speed Estimation with PLL
        3. 2.4.2.3 Field Weakening (FW) and Maximum Torque Per Ampere (MTPA) Control
        4. 2.4.2.4 Compressor Drive with Automatic Vibration Compensation
        5. 2.4.2.5 Fan Drive with Flying Start
        6. 2.4.2.6 Hardware Prerequisites for Motor Drive
          1. 2.4.2.6.1 Motor Current Feedback
            1. 2.4.2.6.1.1 Current Sensing with Three-Shunt
            2. 2.4.2.6.1.2 Current Sensing with Single-Shunt
          2. 2.4.2.6.2 Motor Voltage Feedback
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Getting Started Hardware
      1. 3.1.1 Hardware Board Overview
      2. 3.1.2 Test Conditions
      3. 3.1.3 Test Equipment Required for Board Validation
      4. 3.1.4 Test Setup
    2. 3.2 Getting Started Firmware
      1. 3.2.1 Download and Install Software Required for Board Test
      2. 3.2.2 Opening Project Inside CCS
      3. 3.2.3 Project Structure
    3. 3.3 Test Procedure
      1. 3.3.1 Build Level 1: CPU and Board Setup
        1. 3.3.1.1 Start CCS and Open Project
        2. 3.3.1.2 Build and Load Project
        3. 3.3.1.3 Setup Debug Environment Windows
        4. 3.3.1.4 Run the Code
      2. 3.3.2 Build Level 2: Open Loop Check with ADC Feedback
        1. 3.3.2.1 Start CCS and Open Project
        2. 3.3.2.2 Build and Load Project
        3. 3.3.2.3 Setup Debug Environment Windows
        4. 3.3.2.4 Run the Code
      3. 3.3.3 Build Level 3: Closed Current Loop Check
        1. 3.3.3.1 Start CCS and Open Project
        2. 3.3.3.2 Build and Load Project
        3. 3.3.3.3 Setup Debug Environment Windows
        4. 3.3.3.4 Run the Code
      4. 3.3.4 Build Level 4: Full PFC and Motor Drive Control
        1. 3.3.4.1  Start CCS and Open Project
        2. 3.3.4.2  Build and Load Project
        3. 3.3.4.3  Setup Debug Environment Windows
        4. 3.3.4.4  Run the Code
        5. 3.3.4.5  Run the System
        6. 3.3.4.6  Tuning Motor Drive FOC Parameters
        7. 3.3.4.7  Tuning PFC Parameters
        8. 3.3.4.8  Tuning Field Weakening and MTPA Control Parameters
        9. 3.3.4.9  Tuning Flying Start Control Parameters
        10. 3.3.4.10 Tuning Vibration Compensation Parameters
        11. 3.3.4.11 Tuning Current Sensing Parameters
    4. 3.4 Test Results
      1. 3.4.1 Performance Data and Curves
      2. 3.4.2 Functional Waveforms
      3. 3.4.3 Transient Waveforms
      4. 3.4.4 MCU CPU Load, Memory and Peripherals Usage
        1. 3.4.4.1 CPU Load for Full Implementation
        2. 3.4.4.2 Memory Usage
        3. 3.4.4.3 Peripherals Usage
    5. 3.5 Migrate Firmware to a New Hardware Board
      1. 3.5.1 Configure the PWM, CMPSS, and ADC Modules
      2. 3.5.2 Setup Hardware Board Parameters
      3. 3.5.3 Configure Faults Protection Parameters
      4. 3.5.4 Setup Motor Electrical Parameters
      5. 3.5.5 Setup PFC Control Parameters
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 Bill of Materials
      3. 4.1.3 Altium Project
      4. 4.1.4 Gerber Files
      5. 4.1.5 PCB Layout Guidelines
    2. 4.2 Software Files
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  10. 5Terminology
  11. 6Revision History
2.4.2.6.2 Motor Voltage Feedback

Voltage feedback is needed in the FAST estimator to allow the best performance at the widest speed range, the phase voltages are measured directly from the motor phases instead of a software estimate. The eSMO relies on software estimation values to represent the voltage phases without using the motor phase voltage sensing circuit. This software value (USER_ADC_FULL_SCALE_VOLTAGE_V) depends on the circuit that senses the voltage feedback from the motor phases. Figure 2-35 shows how the motor voltage is filtered and scaled for the ADC input range using a voltage feedback circuit based on resistor dividers. The similar circuit is used to measure all three of both compressor and fan motors, and dc bus.

The maximum phase voltage feedback measurable by the microcontroller in this reference design can be calculated as given in Equation 92, considering the maximum voltage for the ADC input is 3.3 V.

Equation 92. VFS=VADC_FS×Gv=3.3V×122.46=404.13V

Where Gv is attenuation factor can be calculated from

Equation 93. GV=R59+R60+R61+R62R62=332K+332K+332K+8.2K8.2K=122.46

With that voltage feedback circuit, the following setting is done in user_mtr1.h:

//! \brief Defines the maximum voltage at the AD converter
#define USER_M1_ADC_FULL_SCALE_VOLTAGE_V         (404.13f)

The voltage filter pole is needed by the FAST estimator to allow an accurate detection of the voltage feedback. The filter should be low enough to filter out the PWM signals, and at the same time allow a high-speed voltage feedback signal to pass through the filter. As a general guideline, a cutoff frequency of a few hundred Hz is enough to filter out a PWM frequency of 5 to 20 kHz. The hardware filter should only be changed when ultra-high-speed motors are run, which generate phase-voltage frequencies in the order of a few kHz.

The filter pole setting can be calculated as the following Equation 94 in this reference design:

Equation 94. ffilter_pole=12×π×RParallel×C=405.15 Hzwhere, C=47nF RParallel = 332K+332K+332K×8.2K332K+332K+332K+8.2K=8.133kΩ 

The following code example shows how this is defined in user_mtr1.h:

//! \brief Defines the analog voltage filter pole location, Hz
#define USER_M1_VOLTAGE_FILTER_POLE_Hz           (405.15f)
Figure 2-35 Motor Voltage Sensing Circuit