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

2.1.2 DC Voltage Control Loop

In multiple applications, the load or source connected on the DC side of the rectifier stage is not always behaving as a voltage source, indeed the load can act as resistor or current sink or source. When no voltage source behavior is presented by the DC/DC stage, a dependency on the DC bus voltage with the requested power (P_Rec) can lead to no controlled voltage in the output. An uncontrolled DC bus voltage can cause the AC/DC to become unstable, triggering possible current and voltage protections or even damaging the converter itself. To address this, implement an additional control with a higher hierarchical level, with respect to the current loops, as Figure 2-3 shows. A voltage control loop which has the capability to control the active power drained or sourced from the grid by means of I_d* of the lower level control loop Idq was added. The additional PI controller generates a reference (I_d*), which allows matching the rectifier and the load powers (P_Rec and P_Load), by achieving V_DC* equal to V_DC since no power is flowing in the DC-link cap. The matching between the rectifier power and load power is achieved by means of the integrative part.

Figure 2-3 Voltage Plus Current Control Loops

As Figure 2-3 shows, a feedforward which can be achieved by means of a DC current measurement was implemented to decrease the response time of the loop. A generic factor, K, was implemented since this factor is dependent on the voltages, currents, and control technique implementation. This feature is not critical for the converter operation itself but can improve the performance significantly as demonstrated in Section 2.3.

The I_q* reference is independent from the voltage loop since the reference is not involved in the active power regulation, thus in the charging and discharging process of the DC-link cap. As previously mentioned, I_q* directly controls the reactive power of the system.