TIDUF23A May   2023  – May 2025

 

  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  UCC5880-Q1
      2. 2.3.2  F29H859TU-Q1
      3. 2.3.3  UCC14240-Q1
      4. 2.3.4  UCC33421-Q1
      5. 2.3.5  AMC0386-Q1
      6. 2.3.6  AMC0381D-Q1
      7. 2.3.7  TCAN1043-Q1
      8. 2.3.8  ISO1042-Q1
      9. 2.3.9  ALM2403-Q1
      10. 2.3.10 LM5158-Q1
      11. 2.3.11 LM74202-Q1
    4. 2.4 System Design Theory
      1. 2.4.1 Microcontrollers
        1. 2.4.1.1 Microcontroller – C2000™
      2. 2.4.2 Isolated Bias Supply
      3. 2.4.3 Power Tree
        1. 2.4.3.1 Introduction
        2. 2.4.3.2 Power Tree Block Diagram
        3. 2.4.3.3 12V Distribution and Control
        4. 2.4.3.4 Gate Drive Supply
        5. 2.4.3.5 5V Supply Domain
        6. 2.4.3.6 Current and Position Sensing Power
  9. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
      1. 3.1.1 Hardware Board Overview
        1. 3.1.1.1 Control Board
        2. 3.1.1.2 MCU SOM Evaluation Board – C2000™
        3. 3.1.1.3 Gate Driver and Bias Supply Board
        4. 3.1.1.4 DC Bus Voltage Sense
        5. 3.1.1.5 SiC Power Module
          1. 3.1.1.5.1 XM3 SiC Power Module
          2. 3.1.1.5.2 Module Power Terminals
          3. 3.1.1.5.3 Module Signal Terminals
          4. 3.1.1.5.4 Integrated NTC Temperature Sensor
        6. 3.1.1.6 Laminated Busing and DC Bus Capacitors
          1. 3.1.1.6.1 Discharge PCB
    2. 3.2 Test Results
      1. 3.2.1 Isolated Bias Supply
      2. 3.2.2 Isolated Gate Driver
      3. 3.2.3 Inverter System
  10. 4General Texas Instruments High Voltage Evaluation (TI HV EVM) User Safety Guidelines
  11. 5Design and Documentation Support
    1. 5.1 Design Files
      1. 5.1.1 Schematics
      2. 5.1.2 BOM
      3. 5.1.3 PCB Layout Recommendations
        1. 5.1.3.1 Layout Prints
      4. 5.1.4 Altium Project
      5. 5.1.5 Gerber Files
      6. 5.1.6 Assembly Drawings
    2. 5.2 Tools and Software
    3. 5.3 Documentation Support
    4. 5.4 Support Resources
    5. 5.5 Trademarks
  12. 6Revision History
3.1.1.5.4 Integrated NTC Temperature Sensor

The NTC temperature sensor built into the power module is sensed and fed back to the controller through an isolated digital signal. This signal is a 50% duty cycle square wave with varying frequency. The temperature sensor is positioned as close as possible to the power devices while remaining electrically isolated from them and therefore provides an approximate baseplate temperature. The temperature reported by the NTC differs largely from the junction temperature of the SiC MOSFETs and must not be used as an accurate junction temperature measurement. There are two ways to measure the NTC feedback signal for the three XM3 modules with the controller. The first method is using the enhanced capture (eCAP) peripheral to digitally measure the frequency of the signal coming directly from the differential receivers. Figure 3-8 and Table 3-3 give the relationship of the NTC signal frequency to the NTC temperature. For the second method, the frequency signal is filtered and converted into an analog signal which can be measured by ADC on the controller. The analog voltage measures 0.38V when the frequency is 4.6kHz and 2.5V when the frequency is 30.1kHz.

TIDM-02014 NTC Temperature vs Signal Frequency Figure 3-8 NTC Temperature vs Signal Frequency
Table 3-3 NTC Temperature, Resistance, and Frequency Correlation
NTC TEMPERATURE (°C) NTC RESISTANCE (Ω) FREQUENCY OUTPUT (kHz)
0 13491 4.6
25 4700 10.3
50 1928 17.1
75 898 22.8
100 464 26.4
125 260 28.3
150 156 29.5
175 99 30.1
TIDM-02014 CAB450M12XM3 Virtual-Junction Temperature (TVJ) vs NTC Resistance With 25°C Coolant. Figure 3-9 CAB450M12XM3 Virtual-Junction Temperature (TVJ) vs NTC Resistance With 25°C Coolant.

Figure 3-9 shows the mapping between the NTC resistance (RNTC in Ohms) of the CAB450M12XM3 module and the virtual junction temperature (TVJ). Use Equation 4 to calculate the virtual junction temperature.

Equation 4. T V J =   - 87.12 × ln ⁡ R N T C +   786.14

One additional temperature sensor is installed on the controller PCB to provide a measurement of the ambient temperature inside the reference design case. This temperature sensor consists of a 10kΩ NTC surface mount thermistor and a 10kΩ fixed resistor forming a voltage divider. As the temperature increases so does the voltage at the midpoint of the voltage divider. This voltage is low-pass filtered to remove any high-frequency noise from the slowly changing temperature. The conversion between this voltage signal, VT, and the temperature of the thermistor (in Kelvin) is calculated with Equation 5.

Equation 5. T = ( ln ⁡ 3.3 / V T - 1 3900 +   1 298.15 ) - 1