Analysis, Design and Experimental Assessment of a High Power Density Ceramic DC-Link Capacitor for a 800 V 550 kVA Electric Vehicle Drive Inverter

The drive inverter is a crucial component of an electric vehicle (EV) powertrain, being responsible for the DC/AC power conversion between the battery and the electric motor. The increasing demand for lower weight and higher conversion efficiency is opening new challenges, encouraging the adoption of new technologies (e.g., wide bandgap semiconductor devices). In particular, the DC-link capacitor typically represents the bulkiest inverter component, posing a strict limitation to the achievable converter power density and thus being subject to great pressure for improvement. In this context, novel ceramic capacitor technologies (e.g., PLZT) promise superior performance with respect to well established film-based solutions, featuring both higher specific capacitance and higher RMS current capability. Therefore, this paper focuses on the analysis, sizing, design, and experimental assessment of a PLZT-based ceramic DC-link capacitor for next-generation EV drive inverters, including a comparative assessment with a state-of-the-art film-based solution. In particular, in view of the non-linear behavior of the PLZT capacitance value with respect to the DC-bias voltage and the amplitude of the excitation, a novel correlation between the effective large-signal capacitance and the peak-to-peak voltage ripple is derived experimentally, providing useful information for the DC-link capacitor sizing (i.e., not available from the capacitor manufacturer). For verification purposes, a full-scale DC-link capacitor prototype for a SiC MOSFET 800V, 550 kVA, 20 kHz drive inverter is realized, demonstrating superior power density (i.e., ≈ two thirds smaller and ≈ one third lighter than a corresponding film-based solution). Finally, the inverter prototype is also exploited to validate experimentally the proposed DC-link peak-to-peak voltage ripple estimation procedure, based on the newly obtained large-signal capacitance characterization

Analysis and Design of a High Power Density Full-Ceramic 900 V DC-Link Capacitor for a 550 kVA Electric Vehicle Drive Inverter

The drive inverter is a crucial component of an electric vehicle (EV) powertrain, being responsible for the DC/AC power conversion between the battery and the electric motor. The increasing demand for lower weight and higher conversion efficiency is opening new challenges, encouraging the adoption of new technologies (e.g., wide bandgap semiconductor devices). In particular, the DC-link capacitor typically represents the bulkiest inverter component and poses a strict limitation to the achievable converter power density, therefore it is subject to strong pressure for improvement. In this context, novel ceramic capacitor technologies promise superior performance with respect to well established film-based solutions, featuring both higher specific capacitance and higher RMS current capability. Therefore, this paper focuses on the analysis, sizing and design of a full-ceramic 900 V DC-link capacitor for next-generation EV drive inverters, including a comparative assessment with a state-of-the-art film-based solution. For verification purposes, a DC-link prototype for a SiC MOSFET 550 kVA 25 kHz drive inverter is realized, demonstrating superior power density (i.e., ≈ 6.6 times smaller and ≈ 3.6 times lighter than a corresponding film-based solution). Furthermore, electrical and thermal measurements are performed on a ceramic capacitor sample, successfully supporting the DC-link sizing and design

Three-Dimensional in Vivo Anatomical Study of Female Iliac Vein Variations

Objective To investigate female iliac vein variations by using the computed tomography angiography (CTA) three-dimensional (3 D) reconstruction technique. Methods We retrospectively studied 1623 patients undergoing abdominal and pelvic CTA scanning for gynecological diseases from December 2009 to December 2018. Accurate digital 3 D models of the iliac vein were constructed using Mimics 19.0 software and used to study the morphology and variations. Variations in the common iliac vein (CIV), external iliac vein (EIV) and internal iliac vein (IIV) were classified as type I, abnormal number of veins; type II, abnormal communicating branches; or type III, other variations. Results The overall variation rates of the iliac vein and CIV were 51.57% (837/1623) and 20.33% (330/1623), respectively. The main type of CIV variation was type II. The main type I CIV variation was the absence of the CIV (98.15%), which mostly occurred on the right side (64.81%, 35/54). Type II CIV variation was the most common, with abnormal communicating branches between the left CIV and right IIV (81.78%, 211/258). The overall variation rates of the EIV and IIV were 36.66% (595/1623) and 49.60% (805/1623), respectively, mainly on the right side. The main type of variation was type I. Among them, the division of the IIV into two branches plus convergence with the ipsilateral EIV was the most common (22.98%, 373/1623). Conclusion In this study, approximately half of the patients had iliac vein variations. The preoperative identification of iliac vein variation may reduce vascular injury in pelvic surgery

A novel biodegradable polymer-coated sirolimus-eluting stent: 1-year results of the HELIOS registry

Abstract. Background:. The HELIOS stent is a sirolimus-eluting stent with a biodegradable polymer and titanium oxide film as the tie-layer. The study aimed to evaluate the safety and efficacy of HELIOS stent in a real-world setting. Methods:. The HELIOS registry is a prospective, multicenter, cohort study conducted at 38 centers across China between November 2018 and December 2019. A total of 3060 consecutive patients were enrolled after application of minimal inclusion and exclusion criteria. The primary endpoint was target lesion failure (TLF), defined as a composite of cardiac death, non-fatal target vessel myocardial infarction (MI), and clinically indicated target lesion revascularization (TLR) at 1-year follow-up. Kaplan–Meier methods were used to estimate the cumulative incidence of clinical events and construct survival curves. Results:. A total of 2998 (98.0%) patients completed the 1-year follow-up. The 1-year incidence of TLF was 3.10% (94/2998, 95% closed interval: 2.54–3.78%). The rates of cardiac death, non-fatal target vessel MI and clinically indicated TLR were 2.33% (70/2998), 0.20% (6/2998), and 0.70% (21/2998), respectively. The rate of stent thrombosis was 0.33% (10/2998). Age ≥60 years, diabetes mellitus, family history of coronary artery disease, acute myocardial infarction at admission, and device success were independent predictors of TLF at 1 year. Conclusion:. The 1-year incidence rates of TLF and stent thrombosis were 3.10% and 0.33%, respectively, in patients treated with HELIOS stents. Our results provide clinical evidence for interventional cardiologists and policymakers to evaluate HELIOS stent. Clinical trial registration:. ClinicalTrials.gov, NCT0391643

Drug-coated balloon angioplasty with rescue stenting versus intended stenting for the treatment of patients with de novo coronary artery lesions (REC-CAGEFREE I): an open-label, randomised, non-inferiority trial

Background The long-term impact of drug-coated balloon (DCB) angioplasty for the treatment of patients with de novo coronary artery lesions remains uncertain. We aimed to assess the non-inferiority of DCB angioplasty with rescue stenting to intended drug-eluting stent (DES) deployment for patients with de novo, non-complex coronary artery lesions. Methods REC-CAGEFREE I was an open-label, randomised, non-inferiority trial conducted at 43 sites in China. After successful lesion pre-dilatation, patients aged 18 years or older with de novo, non-complex coronary artery disease (irrespective of target vessel diameter) and an indication for percutaneous coronary intervention were randomly assigned (1:1), via a web-based centralised system with block randomisation (block size of two, four, or six) and stratified by site, to paclitaxel-coated balloon angioplasty with the option of rescue stenting due to an unsatisfactory result (DCB group) or intended deployment of second-generation thin-strut sirolimus-eluting stents (DES group). The primary outcome was the device-oriented composite endpoint (DoCE; including cardiovascular death, target vessel myocardial infarction, and clinically and physiologically indicated target lesion revascularisation) assessed at 24 months in the intention-to-treat (ITT) population (ie, all participants randomly assigned to treatment). Non-inferiority was established if the upper limit of the one-sided 95% CI for the absolute risk difference was smaller than 2·68%. Safety was assessed in the ITT population. This study is registered with ClinicalTrials.gov , NCT04561739 . It is closed to accrual and extended follow-up is ongoing. Findings Between Feb 5, 2021, and May 1, 2022, 2272 patients were randomly assigned to the DCB group (1133 [50%]) or the DES group (1139 [50%]). Median age at the time of randomisation was 62 years (IQR 54–69), 1574 (69·3%) of 2272 were male, 698 (30·7%) were female, and all patients were of Chinese ethnicity. 106 (9·4%) of 1133 patients in the DCB group received rescue DES after unsatisfactory DCB angioplasty. As of data cutoff (May 1, 2024), median follow-up was 734 days (IQR 731–739). At 24 months, the DoCE occurred in 72 (6·4%) of 1133 patients in the DCB group and 38 (3·4%) of 1139 in the DES group, with a risk difference of 3·04% in the cumulative event rate (upper boundary of the one-sided 95% CI 4·52; pnon-inferiority=0·65; two-sided 95% CI 1·27–4·81; p=0·0008); the criterion for non-inferiority was not met. During intervention, no acute vessel closures occurred in the DCB group and one (0·1%) of 1139 patients in the DES group had acute vessel closure. Periprocedural myocardial infarction occurred in ten (0·9%) of 1133 patients in the DCB group and nine (0·8%) in the DES group. Interpretation In patients with de novo, non-complex coronary artery disease, irrespective of vessel diameter, a strategy of DCB angioplasty with rescue stenting did not achieve non-inferiority compared with the intended DES implantation in terms of the DoCE at 2 years, which indicates that DES should remain the preferred treatment for this patient population