Considerations for series connection of IGBT and MOSFET switches
28 May 2008
Power Electronics / Power Management
Information from Ixys
Figure 1 shows the typical RC snubber networks for voltage sharing for switches (S) connected in series in a capacitive discharge circuit. A static voltage sharing resistor RS is required so that the switch with the lowest leakage current is not forced into avalanche and a dynamic voltage sharing capacitor CS is needed so that the slowest switch is not forced into avalanche voltage breakdown during turn-on. A compromise must be reached between the number of switches in series, values for RS and CS and cost of the total switch.
The values of the resistors RS and capacitors CS can be computed from the following:
1. Static voltage sharing resistor RS:
RS ≤ (nVS(MAX) – VDC)(n – 1)-1 IS-1
where: n = number of devices in series
VS(MAX) = maximum allowable voltage across a switch (normally 80% of the maximum switch voltage rating)
IS = maximum leakage current of a switch.
Power dissipation in resistor RS:
2. Dynamic voltage sharing capacitor CS: Assuming no reverse current flow through the switches, then the major factor to consider in sizing capacitor CS is the voltage buildup on the last switch to turn-on. It is desirable to prevent the MOSFET from avalanching in order to limit its turn-on losses. The worst case scenario is that the switch sustaining the highest voltage is also the slowest to turn on.
Then:
where: ΔV = Avalanche voltage - VS(MAX)
DtD(ON) = difference in turn-on times
Solving for CS:
Further reading:
Surface mount power amplifier for high-power applications
RF Design
Power Electronics / Power Management
The GNA-63-5W+, from Mini-Circuits, is a GaN MMIC Power Amplifier (PA) designed for demanding RF applications requiring high efficiency, excellent linearity, and a compact footprint.
Read more...
1200 V QSiC modules
Power Electronics / Power Management
SemiQ Inc has launched the QSiC Dual3, a family of 1200 V half-bridge MOSFET modules for motor drives in data centre cooling systems, grid converters in energy storage systems, and industrial drivers.
Read more...
MCOTS transient filter for military applications
RFiber Solutions
Power Electronics / Power Management
SynQor has announced the new MCOTS-F-28-T-HE transient half-brick filter, the latest addition to its MCOTS product family.
Read more...
Expanded range of high-thermal-performance QSiC modules
Power Electronics / Power Management
SemiQ’s half-bridge series for data centre power converters and industrial motor drives features low RDSON SiC MOSFETs and parallel SBD diodes for best-in-class power density and conversion efficiency.
Read more...
Transporting lithium batteries and IoT devices
Power Electronics / Power Management
With billions of rechargeable and non-rechargeable lithium cells and batteries powering most of the world’s consumer and industrial electronic devices, shipping them to customers through vast global logistics chains is often an overlooked topic.
Read more...
Setting a new benchmark for high-power DC load testing
Conical Technologies
Test & Measurement Power Electronics / Power Management
The new ITECH IT8900G/L high-speed, high-power DC electronic load offers a powerful combination of speed, scalability, precision and high-power density.
Read more...
Quality batteries are critical for IIoT
Uniross Batteries
Power Electronics / Power Management
Batteries intended for use in industrial operations must indeed offer complete reliability under extreme environmental conditions, resistance to vibration and harsh environments.
Read more...
12 kW hybrid inverter
Power Electronics / Power Management
Sungrow recently unveiled its next-generation residential energy storage solution, expanding its power range from 5 kW to 12 kW with the introduction of the new MG12RL hybrid inverter.
Read more...
40 W and 75 W railway DC/DC converter
Brabek
Power Electronics / Power Management
RECOM has announced two new cost-efficient DC/DC converters for the rail market with an ultra-wide 11:1 input range to cover all nominal input voltages from 24 to 110 V DC.
Read more...
Power modules for solid-state transformers
RS South Africa
Power Electronics / Power Management
Microchip’s new 3,3 kV silicon carbide modules deliver the required thermal performance and efficiency for SSTs to increase power available for token generation.
Read more...
printer friendly version