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

2.2.1 Isolated AC/DC Power Supply Design

The isolated AC/DC power stage is multiple outputs winding flyback stage based on the UCC28742 device. The UCC28742 controller provides constant-voltage (CV) using an optical coupler to improve transient response to large-load steps. Constant-current (CC) regulation is accomplished through primary-side regulation (PSR) techniques. This device processes information from the optocoupled feedback and an auxiliary flyback winding for precise high-performance control of the output voltage and current. Figure 2-2 shows the system block diagram for the power supply design and the design parameters are shown in Table 2-1.

These are the main components of the power supply:

  • A three-phase input flyback with synchronous rectification supplies three voltages: 12 V (power) and ± 14 V (low power)
  • Two buck converters (based on TPS563210), one dual-LDO (TPS7A3901) and a second LDO (TPS7A2018) take the power from the flyback and supply further 5 V, 3.3 V, 1.8 V, and ± 12 V
  • Two supercapacitors, 2.5 μF each are connected in series and are charged by means of a 120-mA constant current linear regulator, setting the charging voltage to 7.8 V
  • A boost converter with TPS55330 supplies all voltages as soon as mains power is missing
  • A further 12-V input port, protected against overcurrent and reverse polarity, is managed by the eFuse TPS259470, useful during debug. This way the whole system can be supplied without the need of single or three-phase high-voltage input
  • An inverting buck-boost generates ±14 V for the dual-LDO during energy storage discharge, taking power from the regulated 5-V rail
Figure 2-2 Isolated AC/DC Power Supply Block Diagram
Table 2-1 Design Parameters
PARAMETER NOTES AND CONDITIONS MIN NOM MAX UNIT
INPUT CHARACTERISTICS
Input voltage,VIN 85 115, 230 460 VRMS
Maximum input current VIN = VIN(min), IOUT = IOUT(max) 0.8 ARMS
Line frequency 47 60, 50 63 Hz
Desired capacitor bulk voltage, VBULK(desired) 85 V
No load input power consumption VIN(min) ≤ VIN≤ VIN(max), IOUT = 0 A 500 mW
OUTPUT CHARACTERISTICS
Output voltage, VOUT1 VIN(min) ≤ VIN≤ VIN(max) 11.4 12 12.6 V
Output current, IOUT1 2.2 A
Output voltage, VOUT2 VIN(min) ≤ VIN≤ VIN(max) 10.5 12 12.1 V
Output current, IOUT2 0.1 A
Output voltage, VOUT3 VIN(min) ≤ VIN≤ VIN(max) –10.5 –12 –12.1 V
Output current, IOUT3 0.1 A
Total output power, POUT 28.8 W
Output voltage regulation Line regulation: VIN(min) ≤ VIN ≤ VIN(max),
IOUT1 ≤ IOUT1(max)		 0.1%
Load regulation: 0 A ≤ IOUT1 ≤ IOUT1(max) 0.2%
Output voltage ripple VIN(min) ≤ VIN≤ VIN(max),
0 A ≤ IOUT1≤ IOUT1(max)		 100 mVpp
Total output overcurrent, IOCC VIN(min) ≤ VIN≤ VIN(max) 2.4 A
Minimum output voltage, CC mode VIN(min) ≤ VIN≤ VIN(max), IOUT = IOCC 5 V
Brown-out protection IOUT = IOUT(max) 49.9 55.9 61.8 VRMS
Transient response overshoot IOUT = IOUT(max) to 0-A load transient 0.2 V
Transient response time IOUT = IOUT(max) to 0-A load transient 5 ms
SYSTEMS CHARACTERISTICS
Switching frequency, fSW 1.2 40 kHz
Average efficiency 25%, 50%, 75%, 100% load average at nominal input voltages 84.8 85.5 86.2 %
Operating temperature 25 °C