TIDUF60 December   2023

 

  1.   1
  2.   Description
  3.   Resources
  4.   Features
  5.   Applications
  6.   6
  7. 1System Description
    1. 1.1 Terminology
    2. 1.2 Key System Specifications
  8. 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 MSPM0G1507
      3. 2.3.3 TMP6131
      4. 2.3.4 UCC28881
      5. 2.3.5 TPS54202
      6. 2.3.6 TLV9062
      7. 2.3.7 TLV74033
    4. 2.4 System Design Theory
      1. 2.4.1 Hardware Design
        1. 2.4.1.1 Modular Design
        2. 2.4.1.2 High-Voltage Buck Auxiliary Power Supply
        3. 2.4.1.3 DC Link Voltage Sensing
        4. 2.4.1.4 Motor Phase Voltage Sensing
        5. 2.4.1.5 Motor Phase Current Sensing
        6. 2.4.1.6 External Overcurrent Protection
        7. 2.4.1.7 Internal Overcurrent Protection for TMS320F2800F137
      2. 2.4.2 Three-Phase PMSM Drive
        1. 2.4.2.1 Field-Oriented Control of PM Synchronous Motor
          1. 2.4.2.1.1 Space Vector Definition and Projection
            1. 2.4.2.1.1.1 ( a ,   b ) ⇒ ( α , β ) Clarke Transformation
            2. 2.4.2.1.1.2 α , β ⇒ ( d ,   q ) Park Transformation
          2. 2.4.2.1.2 Basic Scheme of FOC for AC Motor
          3. 2.4.2.1.3 Rotor Flux Position
        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 Hardware Prerequisites for Motor Drive
          1. 2.4.2.4.1 Motor Current Feedback
            1. 2.4.2.4.1.1 Three-Shunt Current Sensing
            2. 2.4.2.4.1.2 Single-Shunt Current Sensing
          2. 2.4.2.4.2 Motor Voltage Feedback
  9. 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
    2. 3.2 Getting Started GUI
      1. 3.2.1 Test Setup
      2. 3.2.2 Overview of GUI Software
      3. 3.2.3 Setup Serial Port
      4. 3.2.4 Motor Identification
      5. 3.2.5 Spin Motor
      6. 3.2.6 Motor Fault Status
      7. 3.2.7 Tune Control Parameters
      8. 3.2.8 Virtual Oscilloscope
    3. 3.3 Getting Started C2000 Firmware
      1. 3.3.1 Download and Install Software Required for Board Test
      2. 3.3.2 Opening Project Inside CCS
      3. 3.3.3 Project Structure
      4. 3.3.4 Test Procedure
        1. 3.3.4.1 Build Level 1: CPU and Board Setup
          1. 3.3.4.1.1 Start CCS and Open Project
          2. 3.3.4.1.2 Build and Load Project
          3. 3.3.4.1.3 Setup Debug Environment Windows
          4. 3.3.4.1.4 Run the Code
        2. 3.3.4.2 Build Level 2: Open-Loop Check With ADC Feedback
          1. 3.3.4.2.1 Start CCS and Open Project
          2. 3.3.4.2.2 Build and Load Project
          3. 3.3.4.2.3 Setup Debug Environment Windows
          4. 3.3.4.2.4 Run the Code
        3. 3.3.4.3 Build Level 3: Closed Current Loop Check
          1. 3.3.4.3.1 Start CCS and Open Project
          2. 3.3.4.3.2 Build and Load Project
          3. 3.3.4.3.3 Setup Debug Environment Windows
          4. 3.3.4.3.4 Run the Code
        4. 3.3.4.4 Build Level 4: Full Motor Drive Control
          1. 3.3.4.4.1 Start CCS and Open Project
          2. 3.3.4.4.2 Build and Load Project
          3. 3.3.4.4.3 Setup Debug Environment Windows
          4. 3.3.4.4.4 Run the Code
          5. 3.3.4.4.5 Tuning Motor Drive FOC Parameters
          6. 3.3.4.4.6 Tuning Field Weakening and MTPA Control Parameters
          7. 3.3.4.4.7 Tuning Current Sensing Parameters
    4. 3.4 Test Results
      1. 3.4.1 Load and Thermal Test
      2. 3.4.2 Overcurrent Protection by External Comparator
      3. 3.4.3 Overcurrent Protection by Internal CMPSS
    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
    6. 3.6 Getting Started MSPM0 Firmware
  10. 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 PCB Layout Recommendations
      4. 4.1.4 Altium Project
      5. 4.1.5 Gerber Files
    2. 4.2 Software Files
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks
  11. 5About the Author
2.4.2.4.2 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 2-36 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 55, considering the maximum voltage for the ADC input is 3.3 V.

Equation 55. V F S = V A D C _ F S × G v = 3 . 3 V × 122 . 46 = 404 . 13 V

where

  • Gv is attenuation factor, Gv is calculated with Equation 56
Equation 56. G V = R 62 + R 67 + R 70 + R 74 R 74 = 332 kΩ + 332 kΩ + 332 kΩ + 8 . 2 kΩ 8 . 2 kΩ = 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         (404.1292683f)

The voltage filter pole is needed by the FAST estimator to allow an accurate detection of the voltage feedback. Make the filter 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. Change the hardware filter only when ultra-high-speed motors are run, which generate phase-voltage frequencies in the order of a few kHz.

In this reference design the filter pole setting can be calculated with Equation 57:

Equation 57. f f i l t e r _ p o l e = 1 2 × π × R P a r a l l e l × C = 405 . 15 H z w h e r e ,   C = 47 n F   R P a r a l l e l   =   332 kΩ + 332 kΩ + 332 kΩ × 8 . 2 kΩ 332 kΩ + 332 kΩ + 332 kΩ + 8 . 2 kΩ = 8 . 133 k Ω  

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           (416.3602877f)
GUID-20231030-SS0I-JR8X-5PHL-KCLHP6MRL8MK-low.svg Figure 2-36 Motor Voltage Sensing Circuit