Reliable and Flexible Switching System

[EMJunkie]

@All

The TheOldScientist has done some videos on the schematics I have posted. See Below:

-->The Modular Quadratron Board from Tantratron, Part 1 <--
-->The Modular Quadratron Board from Tantratron, Part 2 <--
-->The Modular Quadratron Board from Tantratron, Part 3. The Half Bridge Topology revisited<--
-->The Modular Quadratron Board from Tantratron, Part 4. The Demux Controller board<--

Again, this is the circuit I have based my design on.

All the Best

  Chris

[Farmhand]

Anyone want to list some pro's and cons for Half bridge and Full Bridge switching solutions for inductive loads ?

Pro's and cons for transformer gate drives and Hi-Lo IC gate drivers ? eg. IRS2110 http://pdf1.alldatasheet.com/datasheet-pdf/view/145601/IRF/IRS2110.html

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[MarkE]

Anyone want to list some pro's and cons for Half bridge and Full Bridge switching solutions for inductive loads ?

Pro's and cons for transformer gate drives and Hi-Lo IC gate drivers ? eg. IRS2110 http://pdf1.alldatasheet.com/datasheet-pdf/view/145601/IRF/IRS2110.html

..

A single transistor and flyback diode give you a backwards sawtooth current waveform:  The current rises quickly (assuming that the drive voltage is much greater than Irated/Rwinding) when the transistor is on and decays slowly recirculating through the inductor and the flyback diode.  The minimum current is set by the input voltage, the coil inductance, the switch minimum on time, and the switching period.

A half-bridge can manage zero average current in the inductor.  You need to make sure that the top and bottom transistors do not conduct at the same time or else you will have shoot through currents that can be very large and destructive.  Half-bridges are common in switching power supplies, and used in sets of three for three phase power supplies and motors.

A full-bridge can manage current in either direction in the inductor.  It is more flexible in that regard than a half-bridge.  It has the same issues as a half bridge, and current must flow through two switches increasing conduction losses.  Full bridges are the preferred form for DC motor and hybrid stepper motor drives.  The ST Micro L298 dual H bridge has been around for almost 30 years.  There are now much more advanced devices for steppers.

Transformer gate drives cannot support DC operation and fast turn-on and turn-off.  There are configurations of transformer drive that support DC using rectifiers and filters on the gate side of the transformer, but they have slow turn-off. 

ICs support DC operation for low side drivers.  Many high side driver ICs drive N channel MOSFETs using charge pumps.  These require that the low side switch turn on periodically in order to recharge the charge pump.  That can be gotten around by various means if needed using extra circuitry.

Use what works for the application and that you can easily obtain.

[Farmhand]

Thanks Mark, I might use the Data sheets and draw up a driver and Half Bridge switch circuit. I already have some IRS2110 driver chips but they are not very high current parts, maybe they can work with moderate frequencies driving IRF460's or FGA25N120-ANTD (IGBT).

If I post a schematic and test the circuit and switching wave forms maybe some folks can suggest improvements. I remember last time i set up an IRS2110 chip and switches I had some trouble with the high side drive initially.

Ta

[Farmhand]

Looking at this page http://www.powerguru.org/the-half-bridge-circuit-revealed/ and the circuit in the data sheet pdf below I made these drawings, I must confess using some kinds of IC's confuses me and this is one of them.

Can anyone see any problems with the circuit for the IRS2110 ? I know some gate resistors may be needed, if I could get operation up to about 25 or 30 kHz I would be happy. Even if I could get good operation up to a few hundred Hz I would be satisfied to begin with.

The circuit with the two batteries just signifies a split EMF. The other one with the capacitor in series with the load coil is kinda like the one from the web page above, he uses a different driver chip.