How good is a Power Ring capacitor?
The Power Ring design results in lower losses, lower inductance and a higher ripple current rating than traditional film capacitor technology. The ring shape provides extremely low internal losses (ESR) and dramatically lowers the inductive properties (ESL). SBE’s Power Ring capacitors show ESR values as low as 0.15 mOhm for a 1000µF – 600V DC Link.
The graph of temperature versus ripple current (above) illustrates the huge improvement in thermal performance delivered by the Power Ring design versus a conventional array of film capacitors. This performance improvement translates to a more efficient use of microfarads where high ripple current is an issue. Design can be optimised for current-handling rather than having to “bulk up” on capacitance only for current handling survival and lifetime requirements – a strategy which has the side-effects of increased cost and size.
How do they do it?
The ultra-low ESR is achieved by shortening the current path between the electrodes. SBE’s patent-pending segmented end spray approach divides the metal end spray into “floating” segments (see diagram). Unlike conventional capacitors, the loss between film and end spray metalisation is so low that current in the end spray can be the dominant loss contributor. The capacitor element ESR can be as low as 50μΩ and the ESR of the end spray/braid can be less than 10μΩ.
Power ring v snubber capacitor
A Power Ring DC link capacitor with integrated bus bar offers a loop inductance that can eliminate the need for a snubber circuit. Snubber capacitors get very hot since they are connected to the IGBT pins (often the hottest point other than under the die itself) and are almost never directly cooled due to the difficulty of connecting cooling plates. Their small size and poor cooling mean snubber capacitors are usually the weak link in the reliability chain for an inverter.
As usable operating voltage increases there can be a tendency to add a snubber to get every bit of safe operating voltage out of a system. The integrated Power Ring capacitor is a more effective method of reducing overshoot, and therefore increasing safe operating voltage, without compromising reliability or system lifetime.
A cooler DC link capacitor means a longer lifetime. A lower ESL means reduced overshoot and undershoot which reduces stress. Removing the requirement for a snubber capacitor means lower costs, a smaller design and a longer lifetime.
Power Ring capacitors
GT series – snubber capacitors
KPST series snubber capacitors
Capacitors from PPM Power
Compact solution for high power pulsed applications
ESP resistors from EBG provide a highly compact solution for high power, pulsed, low frequency applications such as:
- Inrush current limiting
- Capacitor pre-charge and discharge
- Motor control units
- Power supplies,
- Battery charging systems
- Inverter drives.
Right now, these resistors are popular in electric vehicle subsystems as pre-charge resistors and in-rush current limiting devices for industrial power control systems.
Large energy pulses
The special resistive element provides a highly reliable, non-inductive current path capable of handling large energy pulses up to 3300 joules over one second.
The EBG ESP resistor has a very small footprint when compared with thick film, ceramic and wire wound resistors with equivalent peak power ratings, an essential feature for applications where where space is very limited such as electric vehicles or military systems.
Resistor technology comparison table
||Peak Power Rating
Superb build quality
The resistor has superb build quality with large end caps and M4 threads for multiple mounting options. Two diameter sizes are available: 14mm and 20mm. Both sizes are 62mm in length with resistance values between 10 ohms and 1K ohms. Tolerances are +/-5% or +/-10%. If you require tighter specifications please contact a member of the PPM Power technical sales team on 01793 784389.
The PH-A280 series of high voltage input DC-DC converters from TDK-Lambda are now available with 300W output. The DC-DC power modules have a range of 200 to 425Vdc, and are suitable for use in applications using a 380V DC bus such as data centres, telecommunications and renewable energy. The four new models are rated at 12V / 25A, 24V / 12.5A, 28V / 10.8A and 48V / 6.3A. These extend the 50 to 150W PH-A280 product range which already includes outputs of 3.3V, 5V, 12V, 24V, 28V and 48V.
Greater Adjustment Range
The 300W models have a greater adjustment range of -60% to +20% to accommodate non-standard voltages and can provide full load with -40°C to +100°C baseplate temperatures. The range offers efficiencies of up to 92%,
The units follow the industry-standard half-brick package (61.0 x 12.7 x 57.9mm).
The converters can also be conduction cooled making them suitable for use in sealed outdoor enclosures or liquid cooled applications.
Five year warranty
All PH-A280 modules include:
- Five-year warranty,
- Remote on-off
- Over-current and over-voltage protection.
The series is fully isolated with an input to output isolation of 3,000Vac.
Certified to IEC/EN 60950-1, UL/CSA 60950-1 with CE marking for the Low Voltage and RoHS2 Directives.
High Voltage DC-DC power supplies
Overview of power supplies available from PPM
Nanocrystalline is a soft magnetic material composed of 82% iron which has been dubbed the future of magnetic materials in power electronics. Higher permeability means lower loss transformers, which can translate to large reductions in size and weight.
Lower losses, smaller size and reduced weight
The losses of a Nanocrystalline core can be up to two-thirds less than an equivalent Nickel Supermalloy core and up to 80% less than for toroid geometries. Less power is dissipated by the transformer (or inductor) and means the size of cooling components can be reduced.
Ease of switch over from other materials
Nanocrystalline can be formed into any shape and therefore offers a drop-in replacement for existing cores manufactured from other materials, such as Supermalloy or ferrite.
Nanocrystalline v Supermalloy
Nanocrystalline material is more suitable than Supermalloy in applications such as high frequency/broadband transformers, broadband current sensors, high frequency filter chokes and pulse transformers because nanocrystalline offers:
- High permeability over a broad frequency range
- High saturation flux density
- Low losses
Soft magnetic cores from PPM Power
PPM Power can supply tape-wound soft magnetic cores manufactured by MK Magnetics from a range of materials, including grain-oriented silicon steels, 50% and 80% nickel alloys, amorphous material, cobalt alloys and nanocrystalline. Cores up to 1.8m x 1.8m / 1800Kg and strip widths up to 0.6m are possible.
Potential magnetic core weight reduction (2000 Gauss, 20kHz)
Comparison of magnetic materials
|Grain Oriented Silicon Steel
|Standard Crystalline Permalloy
|Advanced Silicon Steel
|High Performance Ferrite
|Advanced Crystalline Permalloy
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