SBAA541 December   2022 AMC3302


  1.   Abstract
  2.   Trademarks
  3. 1Introduction
    1. 1.1 DC Charging Station for Electric Vehicles
    2. 1.2 Current-Sensing Technology Selection and Equivalent Model
      1. 1.2.1 Sensing of the Current With Shunt-Based Solution
      2. 1.2.2 Equivalent Model of the Sensing Technology
  4. 2Current Sensing in AC/DC Converters
    1. 2.1 Basic Hardware and Control Description of AC/DC
      1. 2.1.1 AC Current Control Loops
      2. 2.1.2 DC Voltage Control Loop
    2. 2.2 Point A and B – AC/DC AC Phase-Current Sensing
      1. 2.2.1 Impact of Bandwidth
        1. Steady State Analysis: Fundamental and Zero Crossing Currents
        2. Transient Analysis: Step Power and Voltage Sag Response
      2. 2.2.2 Impact of Latency
        1. Fault Analysis: Grid Short-Circuit
      3. 2.2.3 Impact of Gain Error
        1. Power Disturbance in AC/DC Caused by Gain Error
        2. AC/DC Response to Power Disturbance Caused by Gain Error
      4. 2.2.4 Impact of Offset
    3. 2.3 Point C and D – AC/DC DC Link Current Sensing
      1. 2.3.1 Impact of Bandwidth on Feedforward Performance
      2. 2.3.2 Impact of Latency on Power Switch Protection
      3. 2.3.3 Impact of Gain Error on Power Measurement
        1. Transient Analysis: Feedforward in Point D
      4. 2.3.4 Impact of Offset
    4. 2.4 Summary of Positives and Negatives at Point A, B, C1/2 and D1/2 and Product Suggestions
  5. 3Current Sensing in DC/DC Converters
    1. 3.1 Basic Operation Principle of Isolated DC/DC Converter With Phase-Shift Control
    2. 3.2 Point E, F - DC/DC Current Sensing
      1. 3.2.1 Impact of Bandwidth
      2. 3.2.2 Impact of Gain Error
      3. 3.2.3 Impact of Offset Error
    3. 3.3 Point G - DC/DC Tank Current Sensing
    4. 3.4 Summary of Sensing Points E, F, and G and Product Suggestions
  6. 4Conclusion
  7. 5References


The shift from combustion engines to electric vehicles (EVs) seems inevitable as governments around the world commit to environmental sustainability goals and the automotive industry plans to invest more to accelerate vehicle electrification. The capacity of DC fast-charging stations has increased significantly in recent years. Where the standard was once 150 kW, capacities are now 350 kW and beyond — and the improvements continue. To get to 350 kW and above, a common technology is to stack modules with 20 kW to 40 kW in parallel and perform load balancing of those modules in parallel in a higher level control loop. The current and voltage-sensing technology plays an essential role in the power module control loop of DC fast-charging stations. This application report looks into design considerations for current sensing in EV charging applications, especially with a focus on the gain error, offset, bandwidth, and latency concerning system performance.