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

3.4 Summary of Sensing Points E, F, and G and Product Suggestions

Table 3-1 summarizes the positives and negatives of current sensing points at E, F, and G. Fault protection needs to be handled with smart gate drivers, the current sensors cannot detect fast enough. A significant power loss improvement can be achieved by using the new ZCD shown in Figure 3-8.

Table 3-1 Positives and Negatives of Current Sensing Point at E, F, and G
EFG
Accurate current output regulation(+)(+)(–)
Overcurrent fault protection(–)(–)(+)
Power supply easy(+)(–)(1)(–)
ZCDN/AN/A(+)
(1) Point F needs a floating supply above VOUT+
Table 3-2 Products for Current Sensing at Points E, F, and G
I-Sensing Point Comments, Challenge Iso-Supply Voltage Minimum Bandwidth Maximum Latency CMTI Minimum Accuracy Products (ISO-)AMP | ISO-ADC
E Current in negative branch and fault detection

From lower Gate

Driver

 > 10 kHz – Low < 1% AMC1302 AMC1306M05

| AMC23Cxx| AMC22Cxx
F Current in positive branch and fault detection

Floating above

OUT+ needed

 > 10 kHz – Low < 1% AMC3302AMC3306M05

| AMC23Cxx| AMC22Cxx
G For ZCD

From upper Gate

Driver

 > 1 MHz < 200 ns High –

OPA354|

TLV3501|

ISOW7841| ISOW7741