Introducing the LTK-RCB-5U60A Resonant Capacitor Bank
High-frequency resonant power systems place very different demands on capacitors compared with conventional filtering or energy-storage applications. In a resonant tank, the resonant capacitor bank may be exposed to significant circulating RMS current, making current capability, low impedance, current sharing and interconnection design just as important as the nominal capacitance itself.
With these requirements in mind, we developed the LTK-RCB-5U60A, a compact and modular resonant capacitor bank intended for high-frequency power conversion applications.
The LTK-RCB-5U60A provides a nominal capacitance of 5.0 µF ±5% and is rated for 60 Arms at 100 kHz. The bank is built around five parallel high-ripple-current polypropylene film capacitors, each with a specified ripple-current capability of 14 Arms at 100 kHz.
High-Current Design for a Resonant Capacitor Bank
A resonant capacitor bank is more than a collection of capacitors connected in parallel.
When significant AC current circulates through the tank, the geometry of the current path becomes an important part of the electrical design. For this reason, the LTK-RCB-5U60A uses a high-current, low-impedance PCB architecture, with wide copper current paths and a distributed capacitor arrangement intended to reduce parasitic resistance and inductance while improving current sharing between the individual capacitors.
Instead of concentrating the bank current through a single connection point, each side of the board provides three parallel terminal contacts. Each contact point is limited to 20 Arms, allowing the full 60 Arms bank current to be distributed across the three contacts on both TANK-A and TANK-B terminals. M4 terminal screws are used for the power connections.
This arrangement was selected specifically for applications where high circulating resonant current and low conduction losses are important design considerations.
5.0 µF from Five Parallel Film Capacitors
The capacitor bank consists of five 1.0 µF polypropylene film capacitors connected in parallel, resulting in a total nominal bank capacitance of 5.0 µF ±5%.
The selected capacitors have a voltage class of 1000 VDC / 250 VAC for frequencies up to 1 kHz, while the capacitor bank itself is characterized for a rated bank current of 60 Arms at 100 kHz.
Modular by Design
One of the main design objectives of the LTK-RCB-5U60A was to avoid limiting the capacitor bank to a single fixed system configuration.
The PCB therefore incorporates four mounting points that allow multiple boards to be mechanically stacked. The boards can also be electrically paralleled where a system requires increased total capacitance and current capability.
This makes the same basic capacitor-bank architecture suitable for both single-board resonant tanks and larger multi-board assemblies.
Additional boards can be incorporated into the mechanical and electrical architecture as required by the resonant system, without changing the basic capacitor-bank platform.
Built for High-Frequency Power Applications
The LTK-RCB-5U60A is intended for applications including:
· Induction heating and melting systems
· Series and parallel resonant converters
· High-frequency inverter and transformer-driven resonant tanks
· Laboratory and industrial high-frequency power systems
Its combination of high RMS current capability, low-impedance PCB construction and modular mechanical architecture makes it particularly suited to systems in which the capacitor bank forms an integral part of the high-frequency power path.
LTK-RCB-5U60A — 5.0 µF, 60 Arms at 100 kHz.
