TIDUF17 November   2022 TMS320F2800152-Q1 , TMS320F2800153-Q1 , TMS320F2800154-Q1 , TMS320F2800155 , TMS320F2800155-Q1 , TMS320F2800156-Q1 , TMS320F2800157 , TMS320F2800157-Q1

 

  1.   Description
  2.   Resources
  3.   Features
  4.   Applications
  5.   5
  6. 1System Description
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
    3. 2.3 Highlighted Products
      1. 2.3.1 TMS320F280039C
      2. 2.3.2 UCC21530-Q1
      3. 2.3.3 OPA607-Q1
      4. 2.3.4 LM25184-Q1
      5. 2.3.5 TCAN1044A-Q1
    4. 2.4 System Design Theory
      1. 2.4.1 Three-Phase PMSM Drive
      2. 2.4.2 Field Oriented Control of PM Synchronous Motor
      3. 2.4.3 Field Weakening (FW) and Maximum Torque Per Ampere (MTPA) Control
      4. 2.4.4 Compressor Drive with Automatic Vibration Compensation
      5. 2.4.5 Hardware Prerequisites for Motor Drive
        1. 2.4.5.1 Motor Current Feedback
          1. 2.4.5.1.1 Current Sensing with Three-Shunt
          2. 2.4.5.1.2 Current Sensing with Single-Shunt
        2. 2.4.5.2 Motor Voltage Feedback
  8. 3Hardware, Software, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      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 Test Setup
      1. 3.2.1 Hardware Setup
      2. 3.2.2 Software Setup
        1. 3.2.2.1 Code Composer Studio Project
        2. 3.2.2.2 Software Structure
    3. 3.3 Test Procedure
      1. 3.3.1 Level 1 Incremental Build
        1. 3.3.1.1 Project Setup
        2. 3.3.1.2 Running the Application
      2. 3.3.2 Level 2 Incremental Build
        1. 3.3.2.1 Project Setup
        2. 3.3.2.2 Running the Application
      3. 3.3.3 Level 3 Incremental Build
        1. 3.3.3.1 Project Setup
        2. 3.3.3.2 Running the Application
      4. 3.3.4 Level 4 Incremental Build
        1. 3.3.4.1 Project Setup
        2. 3.3.4.2 Running the Application
        3. 3.3.4.3 Tuning Field Weakening and MTPA Control
        4. 3.3.4.4 Tuning Vibration Compensation
        5. 3.3.4.5 CAN FD Command Interface
    4. 3.4 Test Results
      1. 3.4.1 MCU CPU Load, Memory, and Peripheral Usage
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 BOM
    2. 4.2 Tools and Software
    3. 4.3 Documentation Support
    4. 4.4 Support Resources
    5. 4.5 Trademarks

2.4.5.2 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. This software value (USER_ADC_FULL_SCALE_VOLTAGE_V) depends on the circuit that senses the voltage feedback from the motor phases. Figure 2-20 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 both compressor motor and DC bus.

The maximum phase voltage feedback measurable by the microcontroller in this reference design can be calculated as given in Equation 32, considering the maximum voltage for the ADC input is 3.3 V.

Equation 32. V F S = V A D C _ F S × G v = 3 . 3 V × 293 . 955 = 970 . 05 V

Where Gv is attenuation factor can be calculated from

Equation 33. G V = R 26 + R 27 + R 28 + R 30 R 30 = 499 K + 499 K + 499 K + 5 . 11 K 5 . 11 K = 293 . 955

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         (970.05f)

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 34 in this reference design:

Equation 34. f f i l t e r _ p o l e = 1 2 × π × R P a r a l l e l × C = 664 . 94   H z w h e r e ,   C = 47 n F   R P a r a l l e l   =   499 K + 499 K + 499 K × 5 . 11 K 499 K + 499 K + 499 K + 5 . 11 K = 5 . 0926 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           (664.94f)
Figure 2-20 Motor Voltage Sensing Circuit