JAJU858 December   2022

 

  1.   概要
  2.   リソース
  3.   特長
  4.   アプリケーション
  5.   5
  6. 1System Description
    1.     7
    2. 1.1 EV Charging Station Challenges
      1. 1.1.1 SAE J1772 or Equivalent Standard Compliant EV Charging Stations
      2. 1.1.2 AC and DC Leakage, Residual Current Detection (RCD)
      3. 1.1.3 Efficient Relay and Contactor Drive
      4. 1.1.4 Contact Weld Detection
    3. 1.2 Key System Specifications
  7. 2System Overview
    1. 2.1 Block Diagram
    2. 2.2 Design Considerations
      1. 2.2.1 Isolated AC/DC Power Supply Design
        1. 2.2.1.1  Input Bulk Capacitance and Minimum Bulk Voltage
        2. 2.2.1.2  Transformer Turns-Ratio, Primary Inductance, and Primary Peak Current
        3. 2.2.1.3  Transformer Parameter Calculations: Primary and Secondary RMS Currents
        4. 2.2.1.4  Main Switching Power MOSFET Selection
        5. 2.2.1.5  Rectifying Diode Selection
        6. 2.2.1.6  Output Capacitor Selection
        7. 2.2.1.7  Capacitance on VDD Pin
        8. 2.2.1.8  Open-loop Voltage Regulation Versus Pin Resistor Divider, Line Compensation Resistor
        9. 2.2.1.9  Feedback Elements
        10. 2.2.1.10 Backup Power Supply
        11. 2.2.1.11 Supercapacitor Selection
        12. 2.2.1.12 Supercapacitor Charger Design
      2. 2.2.2 Control Pilot Signal Interface
        1. 2.2.2.1 J1772 Duty Cycle
          1. 2.2.2.1.1 Control Pilot Signal States
          2. 2.2.2.1.2 Control Pilot Signal Circuit
      3. 2.2.3 Relay Drive and Weld Detect
      4. 2.2.4 Residual Current Detection
        1. 2.2.4.1 Auto-Oscillation Circuit
          1.        37
        2. 2.2.4.2 DRV8220 H-Bridge
        3. 2.2.4.3 Saturation Detection Circuit
        4. 2.2.4.4 H-Bridge Controlled by DFF
        5. 2.2.4.5 Filter Stage
        6. 2.2.4.6 Differential to Single-Ended Converter
        7. 2.2.4.7 Low-Pass Filter
        8. 2.2.4.8 Full-Wave Rectifier
        9. 2.2.4.9 MCU Selection
    3. 2.3 Highlighted Products
      1. 2.3.1  UCC28742
      2. 2.3.2  TLV1805
      3. 2.3.3  DRV8220
      4. 2.3.4  ISO1212
      5. 2.3.5  ADC122S051
      6. 2.3.6  TPS7A39
      7. 2.3.7  TPS7A20
      8. 2.3.8  ATL431
      9. 2.3.9  TL431
      10. 2.3.10 TPS563210A
      11. 2.3.11 TPS55330
      12. 2.3.12 TPS259470
      13. 2.3.13 TL7705A
  8. 3Hardware, Testing Requirements, and Test Results
    1. 3.1 Hardware Requirements
    2. 3.2 Test Requirements
      1. 3.2.1 Power Supply Test Setup
      2. 3.2.2 Weld Detect Test Setup
    3. 3.3 Test Results
      1. 3.3.1 Isolated AC/DC Power Supply Based on UCC28742
        1. 3.3.1.1 Efficiency and Output Voltage Cross Regulation
        2. 3.3.1.2 Efficiency and Output Voltage Regulation of TPS563210
        3. 3.3.1.3 Output Voltage Ripple Waveforms
        4. 3.3.1.4 Start, Shutdown, Backup Power, and Transient Response Waveforms
        5. 3.3.1.5 Thermal Performance
      2. 3.3.2 TLV1805-Based Control Pilot Interface
        1. 3.3.2.1 TLV1805 Output Rise and Fall Time
        2. 3.3.2.2 Control Pilot Signal Voltage Accuracy in Different States
      3. 3.3.3 DRV8220-Based Relay and Plug Lock Drive
      4. 3.3.4 ISO1212-Based Isolated Line Voltage Sensing
  9. 4Design and Documentation Support
    1. 4.1 Design Files
      1. 4.1.1 Schematics
      2. 4.1.2 Bill of Materials
    2. 4.2 Documentation Support
    3. 4.3 サポート・リソース
    4. 4.4 Trademarks
  10. 5About the Author
2.2.2.1.1 Control Pilot Signal States

The EVSE connection and negotiation occurs through various states of the PWM signal and load resistances of the vehicle. Table 2-3 highlights these states.

Table 2-3 Pilot Signal State Parameters
STATE PILOT HIGH VOLTAGE PILOT LOW VOLTAGE FREQUENCY RESISTANCE DESCRIPTION
State A 12 V N/A DC N/A Not connected
State B 9 V –12 V 1 kHz 2.74 kΩ EV connected, ready to charge
State C 6 V –12 V 1 kHz 882 Ω EV charging
State D 3 V –12 V 1 kHz 246 Ω EV charging, ventilation required
State E 0 V 0 V N/A — Error
State F N/A –12 V N/A — Unknown error

States A, B, and C are the core functionality and define the normal operation. An EVSE typically performs several self-tests upon initially powering on and then enters State A. When ready, the normal connection process follows several steps:

  1. The EVSE puts 12 V on the pilot wire. This transmission signals the vehicle when the plug is connected.
  2. When the plug is connected, the vehicle places a 2.74-kΩ load on the pilot line, which drops the voltage to 9 V.
  3. The EVSE moves to State B, where the EVSE enables the PWM, which signals the vehicle how much current the vehicle can draw. The EVSE also closes the relays, providing power to the vehicle.
  4. The vehicle starts to draw power and switches to the 822-Ω load, which drops the voltage to 6 V, signaling the EVSE that charging has started.
  5. Most vehicles continue to pull low amounts of power in state C, even when fully charged, so the charging process is ended by unplugging the cable, which returns the voltage to 12 V. The EVSE measures this process and closes the relays and returns to State A.

Additional error handling such as missing diodes in the vehicle or an improper connection can be detected and handled by the EVSE by cutting the power, as well.