DC link capacitors are commonly used in power converters as an intermediary buffer between an input source to an output load that have different instantaneous power, voltages, and frequencies. In electric vehicle (EV) applications, DC link capacitors help offset the effects of inductance in inverters, motor controllers, and battery systems. They also serve as filters that protect EV subsystems from voltage spikes, surges, and electromagnetic interference (EMI).

Ongoing innovation in solar power electronics and rising interest in photovoltaic (PV) installations underscores the importance of robust and efficient electronic components. Capacitors play a key role in power conversion systems as they function to smooth and regulate power flow, protect against voltage surges and filter unwanted signals. 

Today, with the continued drive for more technical features in conventional cars and the increasing electrification of the drive train, the challenges facing electronics designers are ever increasing. Alongside a drive to lower costs and smaller form factors, MLCC’s are being used in ever harsher applications and in ever increasing numbers. This is driving board population density upwards and with it concerns for reliability and particularly the likelihood of mechanical cracking. Thus electronic designers are now demanding flexibility that exceeds the current Automotive Electronic Council bend test specification (AEC-Q200 Rev D June 1, 2010).

The electrical power systems in most modern technologies, like electric vehicles (EVs), are complex. In EVs specifically, power systems are responsible for performing many tasks such as converting AC to DC and DC to AC as well as managing changing power levels in DC/DC conversion. When performing these tasks, manipulating AC voltages and removing noise from DC voltage requires passive components such as capacitors, to perform many “jobs” inside the power system. But no single capacitor type can perform all these jobs since each one has different requirements for voltage, size, temperature, and reliability. Therefore, a variety of capacitor technologies, such as ceramic, film, and aluminum, are required to meet all these needs.

We recently released new supercapacitor modules that provide a significant jump in voltage rating over typical radial-mount supercapacitors, up to 9.0 WVDC.

To help PCBs and other physically connected components survive vibration, board bending, thermal mismatching, and stress during thermal cycling, Knowles Precision Devices has launched a range of leaded standoff components, Metal Frame J-Lead Terminal MLCCs, that are qualified to AEC-Q200. AEC-Q200 is the global standard for stress resistance in passive electronic components in automotive applications. 

Given that snubber capacitors address the negative impacts of switching, it’s no surprise that they’re most commonly found in switching power supplies. These systems face major challenges from switching, including: 

• Switching transients 
• Parasitic elements 
• High-frequency noise 

Capacitors serve many crucial functions in power electronic circuits. Their ability to store electric charge makes them essential components for regulating and smoothing power flow. 

Many of these capacitors are standard fare, but a few play highly specialized, functional roles. To meet application-specific demands, these capacitors must be selected carefully based on function, size, and interoperability. 

As a fundamental component of circuit design, equivalent series resistance (ESR) is the measurement of all the non-ideal electrical resistances in series with a capacitor. When current flows through a multilayer ceramic capacitor (MLCC) due to application of alternating voltage, heat is generated in the MLCC due to the losses, specifically ESR. As a result, this self-heating can cause various performance and reliability issues in the circuits of today’s more complex and smaller electronic systems.

The power electronic systems in an electric vehicle (EV) feature a wide variety of capacitors. From DC-link capacitors to safety capacitors and snubber capacitors, these components play a critical role in stabilizing and safeguarding the electronics from factors like voltage spikes and electromagnetic interference (EMI). Here, we’ll focus on the capacitors used in the EV traction inverter.