Capacitors for high temperature DC link applications in automotive traction drives: Current technology and limitations

Achieving Flat-on Primary Crystals by Nanoconfined Crystallization in High-Temperature Polycarbonate/Poly(vinylidene fluoride) Multilayer Films and Its Effect on Dielectric Insulation

“…4−6 However, its insulation property and lifetime decrease dramatically when the temperature is above 85 °C due to enhanced electronic conduction at high temperatures. 3,7,8 This deficiency requires an extra watercooling system at 60−70 °C for BOPP film capacitors to be used in the power electronic unit having an ambient temperature of ca. 140 °C.…”

“…Electricity is a clean, renewable source of energy that has already been used to replace the fossil fuel energy for transportation. One important component in the power electronics of electric vehicles and high-speed trains is the polymer film capacitor. − The state-of-the-art film capacitors on the market utilize biaxially oriented polypropylene (BOPP) films, primarily owing to its ultralow dielectric loss (dissipation factor, tan δ ∼ 0.0003), high breakdown strength (730 MV/m), and long lifetime (>20 000 h). − However, its insulation property and lifetime decrease dramatically when the temperature is above 85 °C due to enhanced electronic conduction at high temperatures. ,, This deficiency requires an extra water-cooling system at 60–70 °C for BOPP film capacitors to be used in the power electronic unit having an ambient temperature of ca. 140 °C .…”

Active Source Current Filtering to Minimize the DC-Link Capacitor in Switched Reluctance Drives

“…To achieve steady state operation in the next PWM step, i L (t end ) = i * L is applied, resulting in the same duty cycle d CCM as in (5). Due to the control of the average dc-link voltage, the current reference changes only at the first PWM step of the dclink voltage averaging period.…”

“…The ripple increases even further if electric resonant frequencies of the system are excited by the frequency components of the SRM voltage waveforms. A large dc-link capacitor increases the size, weight and price of the SRM inverter compared to inverters for conventional rotating field drives that are based on induction or synchronous machines [5]. Recent publications recommend phase switching techniques to minimize the size of the dc-link capacitor [1], [2], [6]- [8].…”

A highly integrated drive inverter using DirectFETs and ceramic dc-link capacitors for open-end winding machines in electric vehicles

“…In state-of-the-art converters, film capacitors are widely used [7]. The use of ceramic dc-link capacitors is investigated because of their higher capacity density, low ESR and good capabilities for cooling.…”