# Digital Active EMI Filter for Smart Electronic Power Converters

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## Abstract

**:**

## 1. Introduction

- An algorithm that integrates an online adaptive optimization;
- A hardware solution to implement the DAEF in a single board, reporting the selected components for signal acquisition and injection;
- Discussions on perspectives for advanced features that can be supported by DAEFs embedded in smart electronic power converters.

## 2. General Structure and Operating Principle of a DAEF

#### 2.1. Fundamental Blocks

#### 2.2. Operating Principle

## 3. DAEF Control Algorithm

## 4. DAEF Implementation

## 5. Experimental Results

#### 5.1. Experimental Testbench

#### 5.2. Experimental Measurements

## 6. Conclusions

## Author Contributions

## Funding

## Data Availability Statement

## Conflicts of Interest

## Abbreviations

FFT | Fast Fourier transform |

PE | Protective earth |

CM | Common mode |

DM | Differential mode |

ADC | Analog-to-digital converter |

DAC | Digital-to-analog converter |

EMC | Electromagnetic compatibility |

EMI | Electromagnetic interference |

AEF | Active EMI filter |

EUT | Equipment under test |

DAEF | Digital active EMI filter |

WBD | Wide-bandgap device |

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**Figure 1.**Architecture of a DAEF connected at the interface between a noise source, typically referred to as EUT, and the mains.

**Figure 2.**Flowchart of the proposed adaptive control algorithm for the DAEF, comprising the preliminary characterization of the transfer function between voltage injection and sensing [i.e., $H\left(f\right)$].

**Figure 3.**Details of DAEF connected to the considered test setup: (

**a**) main blocks of test setup organization; (

**b**) principle diagram of the DAEF circuit.

**Figure 5.**Comparison between the measured noise with disabled DAEF (blue trace) and after DAEF activation (green trace).

**Figure 7.**Voltage waveforms of the measured EUT noise: (

**a**) EUT noise with DAEF disabled; (

**b**) residual noise after DAEF activation.

Filter Type | Max Attenuation | Features |
---|---|---|

AEF [15] | $-30\phantom{\rule{0.166667em}{0ex}}\mathrm{dB}@150\phantom{\rule{0.166667em}{0ex}}\mathrm{k}\mathrm{Hz}$ | CM/DM reduction |

Hybrid [16] | $-26\phantom{\rule{0.166667em}{0ex}}\mathrm{dB}@4.7\phantom{\rule{0.166667em}{0ex}}\mathrm{M}\mathrm{Hz}$ | Broadband suppression |

DAEF [8] | $-65\phantom{\rule{0.166667em}{0ex}}\mathrm{dB}@400\phantom{\rule{0.166667em}{0ex}}\mathrm{k}\mathrm{Hz}$ | Flexibility, strong reduction |

**Table 2.**Main components of the DAEF circuit (see Figure 3).

Component | Function |
---|---|

ADS4146 | Fast ADC used to sample the noise; 160 MS/s with 14-bit resolution. |

AD9707 | Fast DAC with dual-current output; 175 MS/s with 14-bit resolution. |

LTC6228 | Operational amplifier used to amplify the common mode. |

AD8138 | Single-ended-to-differential driver. |

OPA2675 | High-current-operation amplifier used to drive the injection circuit. |

**Table 3.**Values of the components shown in Figure 3.

Symbol | Value | Symbol | Value | Symbol | Value |
---|---|---|---|---|---|

${R}_{S1}$ | $1.2\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\mathrm{k}\Omega $ | ${R}_{2}$ | $1\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\mathrm{k}\Omega $ | ${R}_{3}$ | $510\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ |

${C}_{s}$ | $5.1\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{F}$ | ${R}_{a}$ | $510\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ | ${R}_{4}$ | $510\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ |

${R}_{s2}$ | $510\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ | ${R}_{b1}$ | $510\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ | ${R}_{j}$ | $150\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ |

${R}_{1}$ | $510\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\Omega $ | ${R}_{b2}$ | $1\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\mathrm{k}\Omega $ | ${C}_{j}$ | $6.8\phantom{\rule{3.33333pt}{0ex}}\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{F}$ |

Freq. (MHz) | ${\mathbf{\Delta}}_{\mathit{noise}}\left({\mathbf{dB}}_{\mathbf{\mu}\mathbf{V}}\right)$ | Freq. (MHz) | ${\mathbf{\Delta}}_{\mathit{noise}}\left({\mathbf{dB}}_{\mathbf{\mu}\mathbf{V}}\right)$ | Freq. (MHz) | ${\mathbf{\Delta}}_{\mathit{noise}}\left({\mathbf{dB}}_{\mathbf{\mu}\mathbf{V}}\right)$ |
---|---|---|---|---|---|

1.171901 | 16 | 1.178127 | 19 | 1.289168 | 19 |

1.296017 | 20 | 1.527364 | 18 | 1.535478 | 13 |

1.644966 | 16 | 4.113723 | 12 | 4.360601 | 14 |

4.721303 | 13 | 4.822430 | 15 | 5.057958 | 18 |

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## Share and Cite

**MDPI and ACS Style**

Darisi, M.; Caldognetto, T.; Biadene, D.; Stellini, M.
Digital Active EMI Filter for Smart Electronic Power Converters. *Electronics* **2024**, *13*, 3889.
https://doi.org/10.3390/electronics13193889

**AMA Style**

Darisi M, Caldognetto T, Biadene D, Stellini M.
Digital Active EMI Filter for Smart Electronic Power Converters. *Electronics*. 2024; 13(19):3889.
https://doi.org/10.3390/electronics13193889

**Chicago/Turabian Style**

Darisi, Michele, Tommaso Caldognetto, Davide Biadene, and Marco Stellini.
2024. "Digital Active EMI Filter for Smart Electronic Power Converters" *Electronics* 13, no. 19: 3889.
https://doi.org/10.3390/electronics13193889