TDK Corporation (TSE: 6762) is excited to launch the TDK SensEI edgeRX, which represents a significant leap forward in industrial maintenance, bringing cutting-edge innovation to the forefront of machine health monitoring.

edgeRX is an advanced machine health monitoring platform that leverages the power of AI on edge sensor devices. By integrating advanced AI algorithms, edge computing, and powerful sensor devices, edgeRX provides real-time machine health monitoring, predictive maintenance insights, and actionable alerts directly on machines. 

edgeRX is a comprehensive, out-of-the-box solution which eliminates the need for extensive setup or specialized integration, allowing reliability engineers, maintenance technicians, and plant managers to quickly deploy and benefit from advanced machine monitoring capabilities. By proactively identifying potential issues before they escalate. edgeRX maximizes uptime, reduces maintenance costs, and enhances overall operational efficiency, making it an indispensable tool in modern manufacturing environments.

Supported by TDK’s extensive history in sensors and components, TDK is well-positioned to build and enhance the edgeRX platform, ensuring best-in-class performance and reliability. With decades of innovation and expertise, TDK Corporation has been a global leader in electronic components, sensors, batteries, and materials technology. TDK's rich legacy of pioneering advancements in these fields provides a strong foundation for the development of cutting-edge solutions like edgeRX.

The integration of snubber capacitors or part of the DC-link capacitance into the power module for inverters is a trend that aims towards improving the overall inverter efficiency and performance on the one hand and lowering the system costs on the other. However, due to the harsh conditions inside the power module, only ceramic capacitors can be considered. CeraLink, a high-voltage ceramic capacitor from TDK, which is specially designed for power electronic applications, can offer significant advantages over standard multilayer ceramic capacitors (MLCCs), especially when it comes to fast-switching power module applications using silicon carbide (SiC) or gallium nitride (GaN).

The power inverter is a crucial component in electric vehicles (xEVs), converting the DC power from the car battery into AC power to drive the motor. High efficiency and reliability are essential to maximize the vehicle's range, performance, and lifetime. More and more xEVs operate at high voltages (typically around 800 to 900 V) to improve efficiency and reduce charging times. The inverter must be capable of handling these high voltages safely and reliably. By using advanced power semiconductors like silicon carbide (SiC) or gallium nitride (GaN) transistors, lower losses and higher efficiency can be achieved. Nevertheless, effective cooling solutions are necessary to manage the heat generated during operation due to losses. Innovative designs, such as double-sided cooling structures, help to optimize thermal performance and reduce the overall size and weight of the inverter, which is important for improving vehicle range and handling. Besides efficiency and performance, also solution cost is important since the development and manufacturing of high-performance power inverters is expensive. One of the main cost drivers in the power module is the SiC dies. Consequently, any possibility of operating these components more efficiently or reducing the number of required dies can bring significant cost savings.

Figure 1a: Schematic of a standard inverter topology with the HV supply (e.g. battery), the inverter module, and a conventional DC-link capacitor solution.

 

 

Figure 1b: Schematic of a standard inverter topology with the HV supply (e.g. battery), the inverter module, and a distributed DC-link capacitor solution where a part of the capacitance is moved close to the power module.
 

Figure 1c: Schematic of a standard inverter topology with the HV supply (e.g. battery), the inverter module, and an integrated snubber within the power module.
 

Depending on the inverter topology, modern power inverters for xEV typically require a DC-link capacitance of several hundred microfarads which is usually realized using e.g. metalized polypropylene film capacitors (Figure 1(a)). However, such film capacitors are bulky and the desired placement close to the switches is often not possible. Hence, there is a significant parasitic inductance between the DC-link capacitor and the SiC MOSFETs. In combination with steep switching slopes (high di/dt), this can lead to severe voltage overshoots, even with a well-designed busbar. These overshoots not only put the switches at risk but also increase the overall system EMC, potentially requiring larger and more expensive filters.

Hybrid systems, as shown in Figure 1(b) and (c), utilize the possibility to split the DC-Link capacitance by moving a smaller capacitance portion from the bulk DC-link as close as possible to (or even inside) the power module. This small capacitance portion is usually realized by compact low-inductive capacitors, e.g. ceramic capacitors. 

As these components are physically close to the switching elements, they can help to suppress voltage overshoots which otherwise potentially damage the switches. Commonly referred to as snubbers or decoupling capacitors, they store excessive energy from the parasitic inductance when the transistor is switched off. The same applies to the turn-on when the parasitic capacitances of the transistor must be instantly charged. If a ceramic capacitor is placed next to the switching device in parallel with the bulk DC-link capacitor, it can provide this current. Otherwise, this current must be drawn from the bulk DC-link capacitor with the higher parasitic inductance since it is further away from the switching transistor.

In such hybrid systems, the parasitic inductances (e.g. busbar and the DC-link) in combination with the snubber capacitance can lead to unwanted resonances which is usually referred to as the anti-resonance effect. This effect can lead to high reactive currents, far beyond the actual snubber current, leading to unexpected heating of the snubber capacitor and a drop in efficiency. This problem gets more severe if the anti-resonance frequency is close to the switching frequency or any relevant harmonics. With a not-optimized design, the anti-resonance frequency can be easily in the range of 200 to 400 kHz, which may already coincide with the harmonics of typical switching frequencies, leading to severe ringing. To mitigate this effect, the anti-resonance needs to be shifted towards higher frequencies. This can be achieved by minimizing the busbar inductance (e.g. by keeping the busbar as short as possible) and reducing the snubber capacitance to the lowest acceptable level. Furthermore, damping elements may be required, preferably with a frequency-dependency (e.g. by utilizing the skin effect). For more details, we refer to [1].

Figure 2: Influence of loop inductance on voltage overshoots at the semiconductor. The larger the inductance loop induced by the distance of the capacitor to the switches, the larger the voltage overshoots and vice versa. With a temperature rating of +150 °C, CeraLink can be placed very close to the semiconductors, therefore minimizing the inductance loop.

The next logical step is the integration of the snubber capacitor directly into the power module as shown in Figure 1(c). In this case, the snubbers can be placed as close to the switching elements as possible, which minimizes the overall loop inductance significantly, as indicated in Figure 2. Therefore, they work very efficiently to filter any voltage spikes and since the induced voltage overshoot is proportional to the parasitic inductance, less capacitance might be needed in the end.

But besides numerous advantages, the integration of capacitors into the power module imposes also several challenges. Only multilayer ceramic capacitors (MLCCs) can meet the requirements for energy density, current capability, temperature rating, and compactness. However, based on the employed ceramic material, different classes of MLCCs are available which all have their pros and cons. In the following, we consider three different materials, namely the well-known Class-I and Class-II dielectrics, but also an anti-ferroelectric dielectric which is used in TDK’s CeraLink and is specifically designed for tomorrow’s power electronic applications.

Pitfall DC bias effect, current capability, and temperature rating

The capacitance of Class-II MLCCs (e.g. X7R temperature class) decreases with the applied DC voltage—known as the DC-bias effect and shown in Figure 3 (a). The exemplary MLCC with Class-II dielectric (X7R), which has a voltage rating of 630 V and a nominal capacitance of 1 µF, provides only a fraction of this value at an operating voltage of 400 V, i.e. the capacitance drops by almost 80% of its nominal value due to the DC-bias effect. Furthermore, the capacitance also decreases with temperature as shown in Figure 3(b). Albeit this effect is usually less dominant compared to the DC-bias effect, particularly at elevated DC-bias voltages. Nevertheless, when both DC-bias and temperature effects are considered, the 1 µF turns into only approximately 0.2 µF at the operating point. This fact is crucial for many designs as the capacitance in the application then differs significantly from the expected value.

Figure 3: Capacitance characteristics as a function of (a) DC-bias voltage and (b) temperature for MLCCs with Class-I (C0G) and Class-II (X7R and X7T) dielectric in comparison with CeraLink.

Another drawback of MLCCs with Class-II dielectric is their limited current capability together with their tendency to show thermal runaway when several capacitors are combined in parallel, i.e. the hottest capacitor in the capacitor array tends to get even hotter such that the system becomes thermally and/or electrically unstable.

Finally, MLCCs with Class-II dielectric are usually limited to +125 °C max. device temperature, which might be on the edge for certain power module applications, since the SiC-MOSFET junction temperature can go up to +175 °C easily. When it then comes to lifetime, it makes a huge difference if the capacitor is operated already close to its upper-temperature specification (e.g. +125 °C) as compared to a capacitor that is rated for +150 °C but operated only at +125 °C. As a rule of thumb, the service life doubles with every 10 K temperature drop. Furthermore, challenging processing conditions during module assembly (e.g. high temperatures during reflow soldering) can be prohibitive for some standard capacitors.

On the other hand, the capacitance of MLCCs with Class-I dielectric (e.g. C0G temperature class) does not significantly depend on DC bias or temperature. Furthermore, they can handle high ambient temperatures as well as high operating currents easily. However, their capacitance density is typically low, requiring that several parts are required to achieve significant capacitance. This takes up a significant amount of PCB area and can lead to space issues, as well as increasing the overall loop inductance. Such a solution counteracts the original idea of having a low-inductive circuit.

Why CeraLink is different

Unlike MLCCs with Class-I or Class-II dielectric, CeraLink capacitors are based on lead lanthanum zirconium titanate (PLZT) ceramics offering an increase in capacitance with DC-bias voltage as shown in Figure 3(a). Furthermore, the capacitance increases with temperature up to a certain maximum and then decreases (refer to Figure 4). This effectively eliminates the risk of thermal runaway.

Figure 4: Capacitance characteristics of CeraLink over temperature and different DC-bias voltages. This characteristic prevents thermal runaway, which can occur in MLCCs with class II dielectrics.

Figure 5: ESR characteristics of CeraLink over frequency. This allows CeraLink to handle higher ripple currents at higher temperatures.

Figure 6: ESR characteristics of CeraLink over temperature and different DC-bias voltages. CeraLink works even more efficiently at high temperatures.

In addition, CeraLink performs very efficiently at elevated temperatures without the need for additional cooling. This is, firstly, achieved by the ESR decreasing with both frequency and temperature (see Figures 5 and 6), allowing it to deliver significantly higher currents in hot environment applications such as power modules. Secondly, CeraLink’s maximum temperature specification of +150 °C allows it to be placed very close to the semiconductors, helping to reduce the effects of parasitic inductance (see Figure 2). This can eliminate the need for additional thermal management, thereby lowering system costs, and reducing both the size and weight of the system. All these features render CeraLink very suitable for fast-switching power electronic applications using wide-bandgap technology.

System cost advantage

For easier comparison, we concentrate in this paragraph on common, standard MLCC case sizes like EIA 2220 with soft termination and AEC-Q200 (automotive) qualification. Furthermore, we consider only non-stacked MLCCs, respectively MLCCs without lead frames. Usually for automotive power module inverter applications a larger capacitance in the range of several hundred nanofarads to some microfarads is required. CeraLink can fulfill this request with the LP (Low Profile) and FA (Flex-Assembly) series.
 

To illustrate the total cost of ownership advantage of CeraLink over MLCCs with Class-II dielectric, consider a snubber application requiring some 50 nF at 800 V. A comparative analysis between CeraLink B58043E9563M052 (56 nF/900 V) and two to four MLCCs (both 1000 V) from various manufacturers demonstrates significant differences (Table 1). Due to the DC-bias effect, these MLCCs achieve only 12.6 nF, respectively 25.9 nF at an operating voltage of 800 V, necessitating three to four parallel units, whereas a single CeraLink 2220 component suffices.

Although the per-1000-unit price for CeraLink as offered by large online distributors is about twice as high as for most MLCCs, the snubber solution with CeraLink is more cost-effective for this application at this operating point. This cost advantage becomes even greater when PCB area and assembly costs are added. The bottom line is that CeraLink can save up to 60% of the cost based on the given example. Note also that the cost savings can be even higher if the benefits of having a less overall circuit inductance which allows for faster and harder switching are considered (e.g. cooling concept, less EMC, and cheaper filters).

Conclusion

Unlike conventional MLCCs with Class-II dielectric, the capacitance of CeraLink increases with DC-bias voltage and temperature up to their operating point. This characteristic makes them highly versatile for various power electronic applications. They excel at suppressing voltage peaks, and, thanks to their low equivalent series inductance (ESL), they are perfectly suited for working hand in hand with fast-switching wide-bandgap semiconductors. Their ability to handle high ripple currents due to low equivalent series resistance (ESR) at high frequencies and temperatures further highlights their adaptability. Additionally, their ability to operate at high temperatures allows them to be placed very close to high-power switches, effectively damping voltage spikes during rapid switching events (Table 2).
 

In addition to their functional benefits, CeraLink capacitors can enhance cost-effectiveness by minimizing or even eliminating the need for thermal management or filtering. This reduction in system costs also contributes to a decrease in the size and weight of the final product. CeraLink is available in different voltage and capacitance ranges which fit different customer requirements.

Next steps in module integration

The next evolutional step in terms of power module design would be the use of multilayer ceramic substrate materials such as aluminum nitride (AlN). This new substrate material from TDK enables many architectural benefits and boosts the power module to the next level.

The efficiency of power modules is typically highest when operating close to their limits, resulting in higher operating temperatures. Precise and accurate temperature control is essential to operate at these limits and to prevent the semiconductors in the power modules from overheating. To address the temperature accuracy challenge, TDK developed lead-free and RoHS-compatible SMD NTC thermistors that describe the corresponding R/T characteristic curves of existing non fully RoHS-compatible technologies available on the market, enabling a seamless substitution.

References

[1] Neudecker, M. and Chatterjee, P., Mitigating DC Link Anti-Resonance for WBG-Based Designs; Bodo’s Power Systems; 10/2024, pp. 42-46

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TDK Corporation (TSE:6762) unveils the EPCOS EP9 series (ordering code: B82804E), which is more compact than the existing E10EM series of surface-mount transformers designed specifically for IGBT and FET gate driver circuits. Engineered for high performance in demanding e-mobility and industrial applications with 500 V system voltage, these components offer exceptional insulation, minimal coupling capacitance, and high thermal resilience. With this new series, TDK is driving the green transformation towards a more electric and sustainable future.

The EP9 series is built on a MnZn ferrite core with SMD L-pin construction, delivering a height of just 11 mm and a footprint of 13 x 11 mm. These transformers operate across a wide temperature range of −40 °C to +150 °C, ensuring durability under harsh conditions. With a coupling capacitance of only 2 pF, complying with the AEC-Q200 Rev. E standard, and creepage and clearance of at least 5 mm, these surface-mount components are generally used in automotive applications and other demanding environments.

The transformers support topologies such as half-bridge and push-pull converters with typical operational frequency of 100 to 400 kHz and turns ratios optimized for specific applications. These components are available in tape-and-reel packaging, ensuring ease of assembly for high-volume production environments.

A sample kit is available under order number B82804X1, containing six transformers of each version.

TDK Corporation (TSE:6762) announces the X1 capacitors of the EPCOS B3291xH/J4 series for power line filtering of electromagnetic interferences (EMI) in demanding automotive and industrial applications with a rated AC voltage of up to 480 V. Applications that are exposed to harsh climatic conditions such as PV inverters and EV onboard chargers (OBCs) can benefit from the new X1 capacitors’ high resistance to high humidity environments. With the ability to continuously handle a DC voltage of 1000 V, this series is a dedicated solution for DC EMC of high-voltage EV platforms.

The X1 capacitors are THB-tested (temperature, humidity, bias) at +85 °C, 85% relative humidity for 1000 hours at 380 V (AC) and 1000 V (DC), and they can operate at temperatures up to +110 °C.

Featuring self-healing properties, the series covers capacitance values from 15 nF to 10.0 µF and boasts a compact design, with dimensions ranging from 18.0 x 10.5 x 5.0 mm to 57.5 x 57 x 45 mm, depending on the capacitance. Lead spacings vary between 15 mm and 52.5 mm, with the largest versions equipped with 4 pins for enhanced mechanical stability on the PCB. The series is certified according to ENEC, UL, and CSA standards.

TDK Corporation (TSE:6762) announces the launch of the EPCOS B3292xM3/N3 series of X2 EMI suppression capacitors. These new components are 20% smaller than previous models and meet Grade III Test B standards for temperature, humidity, and bias (THB). Their compact size and enhanced durability suit space-constrained, high-humidity environments, especially for "across-the-line" applications in automotive and industrial settings.

The capacitors offer lead spacings from 15 mm to 37.5 mm and dimensions ranging from 18.0 x 5.0 x 10.5 mm to 42.0 x 14.0 x 25.0 mm (L x W x H), with capacitance values from 0.1 µF to 4.7 µF. Designed for harsh environments and AEC-Q200 compliant, the B3292xM3/N3 series is commonly used in automotive on-board chargers (OBCs), as well as industrial systems such as uninterruptible power supplies (UPS) and hybrid inverters for energy storage systems (ESS).

To meet Grade III Test B standards, they are tested at +85 °C and 85% relative humidity and subjected to rated AC voltage stress for 1000 hours (with lead spacing of 22.5 mm or more) or 500 hours (with 15 mm lead spacing). The components are rated for an AC voltage of 305 V and can handle a maximum DC voltage of 630 V continuously. With an operating temperature range of -40 °C to +110 °C, and self-healing properties due to their metalized polypropylene (MKP) dielectric, the B3292xM3/N3 series offers long-term reliability.

With its compact size and advanced durability, the B3292xM3/N3 series offers a reliable, high-performance solution for EMI suppression, helping engineers save space and maintain reliability in demanding environments.

TDK Corporation (TSE:6762) announces the L862 (B57862L) NTC thermistors with bendable wires and the L871 (B57871L) lead spacing NTC thermistors that can be used in a wide range of automotive and industrial applications. Both series are Pb-free and can measure temperatures between -40 °C and +155 °C with a tolerance of ±1% and ±3% respectively. At room temperature, their maximum power dissipation is 60 mW. Both series are available with different rated resistances between 1 kΩ and 100 kΩ and different R/T characteristics (see tables below and on the next page). After 10,000 h at +70 °C, the deviation of the resistance at room temperature R₂₅ is less than 3%.

The sensor element of the L862 that is encapsulated with a black epoxy coating is just 2.6 x 6.5 mm (D x H) in size and has insulated leads of silver-plated nickel wire (AWG 30, Ø 0.25 mm). The total length of the sensor including the wires is 50 mm, with 6 mm stripped. While the dissipation factor δ_th of the sensor is 1.4 mW/K, its thermal cooling time constant τ_c is 14 s.

Also, the sensor element of the L871 is encapsulated with a black epoxy coating. It is just 2.8 x 6.0 mm (D x H) in size and has Cu-clad steel wires (Ø 0.4 mm) with a spacing of 2.5 mm. While the dissipation factor δ_th of the sensor is 3 mW/K, its thermal cooling time constant τ_c is 9 s.

TDK Corporation (TSE:6762) announces two new additions to its high-voltage contactor portfolio for harsh environments: the HVC43MC with integrated mirror contact and the HVC45 with enhanced short-circuit current handling capability. These new contactors for up to 1000 V (DC) enable reliable switching of lithium-ion batteries in traction applications, energy storage systems (ESS), and DC charging stations. These components underscore TDK’s dedication to enabling the transition to a greener, more electrified future.

With an integrated mirror contact according to IEC 60947-4-1, the HVC43MC enables safe detection of the main contact's position. This mechanically linked auxiliary contact provides reliable feedback about whether the main contact has opened or closed, enhancing system safety monitoring. The contactor can handle continuous currents up to 250 A and cut-off currents up to 450 A at 1000 V (DC) and 2000 A at 450 V (DC), respectively, all in a compact package measuring 74.5 x 78 x 40.5 mm.

With a short-circuit current handling capability of up to 12 kA for 5 ms, the HVC45 sets an industry benchmark, surpassing conventional solutions in its size class that typically achieve 8 to 10 kA. This enhanced capability addresses the requirements of modern high-energy-density batteries that can achieve higher short-circuit currents. The contactor can handle continuous currents up to 300 A and features a maximum cut-off rating of 900 A at 1000 V (DC) and 2200 A at 450 V (DC), respectively.

Both series incorporate TDK's proven gas-filled ceramic arc chamber technology and bidirectional switching capability, allowing current flow in both directions. The contactors are available with 12-V or 24-V coil voltages and are certified to CE, UKCA, and UL standards, supporting worldwide deployment.