Today, many electrical systems are demanding higher operating voltages and temperatures, along with higher capacitance values – particularly in the fast-growing area of power electronics for electric vehicles (EVs). Therefore, electrical design engineers are looking to use multilayer ceramic capacitors (MLCCs) in these applications due to their inherent low inductance and wide operating temperature range.

In electric vehicle (EV) applications, filter capacitors are a special type of component commonly used as input and output capacitors. Also known as noise suppression or electromagnetic interference (EMI) filters, these particular capacitors act to remove noise and other unwanted signals on the line. On the high voltage alternating current (AC) side of a system, the capacitors often provide EMI filtering, whereas on the direct current (DC) side of a subsystem, they serve to smooth ripple components of the AC and filter out noise.

In recent years, multilayer ceramic capacitors (MLCCs) have emerged as an excellent capacitor option for the high-power electrical systems needed in electric vehicle (EVs) due to their small physical size, low inductance, and ability to operate at higher temperatures. However, EV engineers are facing two big challenges with using MLCCs including DC bias that can cause capacitance loses of 80 to 90 percent of their quoted value and self-heating issues from AC ripple that can lead to inefficiencies in circuits as well as increased cooling demands. 

Many power electronics today are being designed for use in high-temperature, high-voltage environments, such as inside electric vehicles (EVs). However, size, weight, and power (SWaP) are also key factors driving electronic product development. These conflicting design criteria are an issue for many electrical engineers because space is not available to simply add a cooling system, as this will add weight and increase the product’s overall footprint. Therefore, many of these electronic components are susceptible to “running hot” at the high temperatures and high voltages used in these tiny spaces.

Achieving high capacitance means going big. But how do you do that while still maximizing board space? At Knowles Precision Devices, we’ve developed a new method for building customizable large capacitor assemblies that capitalize on the vertical space above the circuit board. While stacked capacitor assemblies have been around for many years, these parts do not have very good bump and vibration withstand due to the thin leads used in their construction. These new assemblies from Knowles Precision Devices offer a ruggedized construction capable of withstanding high levels of shock and vibration. This offers a unique combination of capability, durability, high capacitance, and very high voltage in a smaller area, making these capacitors ideal for automotive, military, and aerospace applications.

At Knowles Precision Devices, we purposely avoid commodity components. What we thrive on is doing the hard things. We handle the specialty components that go in systems that cannot fail and that operate at extremely high voltages, temperatures, or frequencies. Do you have a complex technical challenge with hard-to-meet performance, size, or other requirements? Bring it to us. It’s what we do.

To meet consumer demand for longer driving ranges and faster charging, electric vehicle (EV) manufacturers are redesigning vehicles to move from 400V to 800V battery systems. As a result of using higher operating voltages, EV designers and original equipment manufacturers (OEMs) need components, such as multi-layer ceramic capacitors (MLCCs), that can withstand voltages well beyond those expected under normal operating conditions. For example, a drivetrain running off an 800V battery system may be subjected to a withstand test of up to 4kV DC for 60 seconds, which is a standard safety test in high voltage systems.

Today, the design and development of many applications, such as power electronics in electric vehicles (EVs), is driven largely by concerns about size and weight. This means the film capacitors traditionally used by electronics engineers aren’t always the best option. Instead, multi-layer ceramic capacitors (MLCCs) are emerging as an excellent alternative to film capacitors. Let’s review some of the considerations to keep in mind when you are deciding if making the switch is the right choice for your application.  

When an engineer designs a circuit, he or she needs to ensure that each component will “do what it says on the box.” In multi-layer ceramic capacitor (MLCC) design, one area that often concerns engineers is the fact that capacitance can fluctuate with voltage, which is known as “DC bias” or “voltage coefficient.”

As countries around the world tighten emissions standards, the demand for fully electric vehicles (EVs) is increasing. However, for EVs to see mainstream adoption, manufacturers must address the primary consumer concerns: longer driving ranges and faster charging. To address these concerns, EV manufacturers are beginning to redesign their vehicles to switch from the 400V battery systems widely used today to 800V battery systems, which can offer twice the voltage and 2.7 times the power density compared to a 400V system.