Effective electromagnetic interference (EMI) filters are required by switching converters to comply with conducted emission regulations. However, these filters often pose significant challenges, being expensive, bulky, and heavy. Such an issue is further aggravated with the latest generation of wide band gap (WBG)-based power converters. Reduction of the filter size can be achieved through conducted EMI mitigation techniques that address emissions at the source, particularly at low frequencies. Spread-spectrum modulation (SSM) has gained increasing interest to mitigate EMI, as it does not require any hardware alterations. This article investigates the effectiveness of the SSM in case of WBG traction inverters, where the switching frequency remains in the tens of kilohertz. In addition, the use of an additional switching leg to reduce the EMI was also investigated. A comparative analysis of these two techniques and their effectiveness in the common mode (CM) conducted EMI suppression is carried out. Experimental results are provided demonstrating the feasible CM conducted EMI reduction. It was found that the EMI peak at 160 kHz decreased by 2 dB in the SSM case and by 25 dB in the additional leg case.

The structural complexity of real-world pipeline networks makes it difficult to derive physics-based models of acoustic propagation. This work deals with the design of a communication system based on the propagation of acoustic waves in water-filled pipes. A method based on the experimental characterization of the communication channel is proposed. This approach is applied to an urban water distribution pipeline, and a black-box model representing its frequency response is obtained. The derived two-port model is used for the simulation of a complete communication system, comprising transmitter and receiver models, with the aim of using the water pipe as a wireless communication channel. It is shown that the choice of modulation parameters is critical in order to deal with issues such as the frequency selectivity of the channel and multipath wave propagation. A communication system is presented and the experimental results of the communicated data are provided.

Frequency characterization of spatially-large structures has become increasingly required, mostly in the fields of Structural Health Monitoring and Communication Systems based on non conventional media. When the ports of the system under measurement are far apart, methods based on traditional wired instruments become unattractive for field applications, due to the increased complexity, cost and signal integrity related issues. Aiming towards removing the wired connection from the ports of the system under test and the elaboration unit, the main issue to be dealt with is the time-synchronization of measurements at the ports. This contribution proposes a solution to such an issue by presenting a Wireless Vector Network Analyzer, suitable for the characterization of distributed systems. For this purpose, a wireless synchronization scheme is proposed, which is based on the disciplining of the signal sampling clock from the 1-Pulse-Per-Second reference signal. The proposed synchronization method reduces clock jitter at different ports at 1.13 μs over a 300 s observation interval. The hardware and software implementation of the system are detailed and experimental results proving its operation are provided.

Electromagnetic interference (EMI) filters play a crucial role in automotive inverters but can occupy a significant portion of the overall system volume, particularly in wide-bandgap (WBG) semiconductor-based designs, due to their higher power density compared to Silicon-based ones. To address this issue, this article proposes the use of active capacitors as a replacement for passive ones, effectively reducing the required common-mode (CM) inductance. A detailed analysis of the active capacitor operation is presented, along with design equations to aid implementation. Based on this approach, a hybrid EMI filter (HEF) is proposed. Experimental prototypes have been developed and tested to validate the concept. The results demonstrate that the HEF achieves comparable filtering performance to conventional passive designs while reducing the volume of magnetic components by 50%.

$$\varDelta \varSigma $$Δ Σ analog-to-digital converters (ADCs) are largely used in sensor acquisition applications. In the last few years, standalone $$\varDelta \varSigma $$Δ Σ modulators have become increasingly available as off-the-shelf parts. To build a complete ADC, a standalone modulator has to be paired with some advanced elaboration unit, such as a field programmable gate array (FPGA) or a digital signal processor (DSP), which is needed for the implementation of the decimation filter. This work investigates the use of low-cost, general-purpose microcontrollers for the decimation of $$\varDelta \varSigma $$Δ Σ -modulated signals. The main challenge is given by the clock frequency of the modulator, which can be in the range of a few $$\hbox {MHz}$$MHz . The proposed technique deals with this limitation by employing two serial peripheral interface (SPI) modules in a time-interleaved configuration. This approach allows for continuous acquisition and elaboration of relatively high-speed, digital signals. The technique has been applied to a case study, and a data conversion system has been practically realized. The performance of the proposed filter is compared to that of a digital filter, present on board a commercial microcontroller, and the results of experimental tests are provided.

Communication systems based on in-pipe acoustic propagation have great potential to cover areas in which traditional infrastructure is unavailable. Characterization of the channel plays an important role in the design of any communication system. However, in case of spatially large channels, this aspect needs further investigations. In the present work, a method for the characterization of an acoustic channel is presented. This is based on the measurement of the complex transfer functions relating voltages and pressures at the channel ports. Such a technique was validated on a 75 m long segment of a urban water distribution pipeline. The measurements assessed the frequency selectivity of the acoustic channel and the wave propagation speed. From experimental results, the response of the acoustic channel had an overall low-pass behavior, but it showed several deep notches at low frequency.