SBAA541 December   2022 AMC1202 , AMC1302 , AMC1306M05 , AMC22C11 , AMC22C12 , AMC23C10 , AMC23C11 , AMC23C12 , AMC23C14 , AMC23C15 , AMC3302 , AMC3306M05

 

  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. 2.2.1.1 Steady State Analysis: Fundamental and Zero Crossing Currents
        2. 2.2.1.2 Transient Analysis: Step Power and Voltage Sag Response
      2. 2.2.2 Impact of Latency
        1. 2.2.2.1 Fault Analysis: Grid Short-Circuit
      3. 2.2.3 Impact of Gain Error
        1. 2.2.3.1 Power Disturbance in AC/DC Caused by Gain Error
        2. 2.2.3.2 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. 2.3.3.1 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

2.2 Point A and B – AC/DC AC Phase-Current Sensing

This section describes design considerations of current sensors placed in the point of common coupling (point A) or switching node (point B). Investigation results of the control loop performances mentioned in Section 2.1 when sensing parameters are changed are provided.

Offset, bandwidth, gain error, and latency of the current sensors are discussed at a system level with the aim to determine the minimum requirements. Not all scenarios are covered for both points A and B since many cases turned out to be a repetition, only the worst cases are described to determine minimum requirements. The following list shows all the details about the analysis of each current-sensor specification:

  • Sensor Bandwidth: Analysis was conducted on both points A and B. In point A because the phase error needs to be negligible for the reactive power control. In point B because the AC currents need to be controlled as fast as possible.
  • Highest Latency: Analysis was conducted only in the switching node because point B is the closest point to the power switches which require protection. Furthermore, between point A and B there is an EMI filter which can create a mismatch between the current present from the switching node with respect to the PCC.
  • Gain Error: The impact of gain error is the same in both PCC and switching node. The analysis was conducted in the switching node because in point B higher current control loop bandwidth can be achieved, leading to a higher THD of the current when accuracy error is present. Subsequently, when the higher bandwidth is present in the system, the voltage loop injects noise in the grid currents.
  • Offset Error: The impact of offset error is the same in both PCC and switching node. The analysis was conducted in the switching node because the switching node is the place where higher current control loop bandwidth can be achieved, leading to a higher THD of the current when an offset is present.