Structural Resemblance Between Droop Controllers and Phase-Locked Loops

It is well known that droop control is fundamental to the operation of power systems and now the parallel operation of inverters while phase-locked loops (PLL) are widely adopted in modern electrical engineering. In this paper, it is shown at first that droop control and PLLs structurally resemble each other. This bridges the gap between the two communities working on droop control and PLLs. As a result, droop controllers and PLLs can be improved and further developed via adopting the advancements in the other field. This finding is then applied to operate the conventional droop controller for inverters with inductive output impedance to achieve the function of PLLs, without having a dedicated synchronization unit. Extensive experimental results are provided to validate the theoretical analysis

Robust stability analysis of a dc/dc buck converter under multiple parametric uncertainties

Stability studies are a crucial part of the design of power electronic systems, especially for safety critical ap¬plications. Standard methods can guarantee stability under nominal conditions but do not take into account the multiple uncertainties that are inherent in the physical system or in the system model. These uncertainties, if unaccounted for, may lead to highly optimistic or even erroneous stability margins. The structured singular value-based method justifiably takes into account all possible uncertainties in the system. However, the application of the method to power electronic systems with multiple uncertainties is not widely discussed in the literature. This work presents practical approaches to applying the method in the robust stability analysis of such uncertain systems. Further, it reveals the significant impact of various types of parametric uncertainties on the reliability of stability assessments of power electronic systems. This is achieved by examining the robust stability margin of the dc/dc buck converter system, when it is subject to variations in system load, line resistance, operating temperature and uncertainties in the system model. The predictions are supported by time domain simulation and experimental results

Sizing of power electronics EMC filters using design by optimization methodology

This paper proposes a synthesis of EMC filter design method for power electronics converters. It starts with the description of the legacy approach, using the usual Common Mode / Differential Mode decomposition, and underlines the need of symmetry and the associated limits. Then an illustration of a design by optimization process is provided in the case of a simple switching cell. Finally, a full system composed of a PFC rectifier is provided, using EMC filters on both AC and DC sides. This example requires a design by optimization, since the two filters exhibit strong interactions

The More-Electric Aircraft and Beyond

Aviation is a significant contributor to greenhouse gas (GHG) emissions in the transportation sector. As the adoption of electric cars increases and GHG emissions due to other modes of transport decrease, the impact of air travel on environmental pollution has become even more significant. To reduce pollution and maintenance, and ensure cheaper and more convenient flights, industry and academia have directed their efforts toward aircraft electrification. Considering various types of aircraft, several frameworks have been proposed: more-electric aircraft (MEA), hybrid electric aircraft (HEA), and all-electric aircraft (AEA). In the MEA framework, propulsion is generated by a conventional jet engine; however, all secondary systems (hydraulic, pneumatic, and actuation) are electrified. By further increasing electrification, electric motors can provide propulsion with the electric power supplied by the conventional engine (i.e., HEA) or from electrical energy storage (i.e., AEA). Power electronics and electrical machines play a key role in this scenario in which electric power must be efficiently generated, distributed, and consumed to satisfy extremely high requirements of aviation safety. This article provides an overview of recent advancements in aircraft electrification, and trends and future developments referenced to the global aviation roadmap

10-kV SiC MOSFET Power Module With Reduced Common-Mode Noise and Electric Field

The advancement of silicon carbide (SiC) power devices with voltage ratings exceeding 10 kV is expected to revolutionize medium- and high-voltage systems. However, present power module packages are limiting the performance of these unique switches. The objective of this research is to push the boundaries of high-density, high-speed, 10-kV power module packaging. The proposed package addresses the well-known electromagnetic and thermal challenges, as well as the prominent electrostatic and electromagnetic interference (EMI) issues associated with high-speed, 10-kV devices. The high-speed switching and high voltage rating of these devices causes significant EMI and high electric fields. Existing power module packages are unable to address these challenges, resulting in detrimental EMI and partial discharge that limit the converter operation. This article presents the design and testing of a 10-kV SiC mosfet power module that switches at a record 250 V/ns without compromising the signal and ground integrity due to an integrated screen reduces the common-mode current by ten times. This screen connection simultaneously increases the partial discharge inception voltage by more than 50%. With the integrated cooling system, the power module prototype achieves a power density of 4 W/mm 3

Optimal control of three-phase embedded power grids

This paper presents an automated and scalable approach for the tuning of power converters control systems in embedded power grids. These are composed by different power converter interconnected to each other and are increasingly adopted in a range of applications among which micro-grids and more electric aircrafts. The interaction between the grid components may lead to instability, especially in presence of small passive filters. A structured state feedback optimal control approach is proposed to jointly design all power converters controllers in a coordinated way to maximize the performance of the grid and avoid instability due to converters interactio

Taking into account interactions between converters in the design of aircraft power networks

This paper presents some key interactions among converters, which need to be taken into account when designing a modern embedded electrical grid, including a large amount of Power Electronics based loads. A design by Optimization method is first used to define the converter parameters. During this step, it is mandatory to account for the interaction between the input and output EMI filters. The second step consists in designing the control strategy; the paper will show that the results are largely improved if all converters are considered simultaneously. Finally, the stability study of the embedded network has to be investigated. All these interactions are studied in the example of a three phases AC network, composed of a Voltage Source Inverter and an Active Front End

A wire-bond-less 10 KV SiC MOSFET power module with reduced common-mode noise and electric field

While wide-bandgap devices offer many benefits, they also bring new challenges for designers. In particular, the new 10 kV silicon carbide (SiC) MOSFETs can switch higher voltages faster and with lower losses than silicon devices while also being smaller in size. These features can result in premature dielectric breakdown, higher voltage overshoots, high-frequency current and voltage oscillations, and greater electromagnetic interference. In order to mitigate these side effects and thus fully utilize the benefits of these unique devices, advanced module packaging is needed. This work proposes a power module package with a small footprint (68 mm × 83 mm), low gate- and power-loop inductances (4 nH), increased partial discharge inception voltage (53 %), and reduced common-mode current (90 %)