/*********** Vorlage für Eigenbau-Seiten im ElektronIQ-Wiki. ***********/ /* Nicht gebrauchte Abschnitte bitte löschen, oder auskommentieren. */ /************************************************************-<(kmk)>***/ ====== CurrentStabilisation ====== /* Ein Titelbild: */ /* {{:eigenbau:currentlimit:BILDNAME.jpg?300|}} */ ==== Funktion ==== One device, multiple tasks: * Power Supply for LEM ULTRASTAB via D-Sub * Read current & transduce to Voltage with high precision option * Set current via analog input * switch current on/off via MOSFET control * PID feedback to (high current) power supply including sample and hold option * PID feedback to MOSFET to control / switch current with output offset * interlock (ULTRASTAB status, external) /* Was das Ding tun soll */ /* Ausführlichere Beschreibung: {{:eigenbau:currentlimit:currentlimit.lyx|}} */ ==== Optionen und Alternativen ==== * There is a footprint for [[http://www.vishaypg.com/docs/63240/VCS-VFP-CSNG.pdf|ultra high precision current sensing resistor]]. * instead of ULTRASTAB D-Sub, a BNC can be connected to current input * via population you can select whether to measure current or voltage (no shunt resistor). Then it should be usable as dual PID. * PSU output limit (0-10V) can easily be disabled /* Wie man das Gerät sonst noch missbrauchen kann */ ==== Performance ==== FIXME /* Wie schnell, weit, hoch das Ding auf den Bäumen ist */ ==== Date ==== Begin of Project: Oktober 2016 /* Die Zeit zu der das Projekt begonnen wurde */ ==== Status ==== * schematic and pcb layout done on KiCad * version v1a ordered at Basista on 2016-11-01, 3 pc for prototyping /* reine Idee / Prototyp / fertig zur Massenproduktion ... */ Aufwand für Nachbau: FIXME ==== Entwickler ==== Christian Meiners, meiners@iqo.uni-hannover.de /* Auf wessen Mist das Ding gewachsen ist. Default: Der User, der die Dokuwikiseite anlegt.*/ Main Ideas based on prototypes an schematics from Klaus Zipfel. ==== Anwender ==== VLBAI Magnesium /* Wer das Ding bisher benutzt */ ==== Schaltungsprinzip ==== current from LEM ultrastab is transduced to voltage using a shunt and a diffamp. A error signal is generated by adding a iverted set signal. This error signal is fed into two PIDs. PID A has A Sample and hold option which works as follows: the PID output is fed into the S&H circuit, once activated the S&H outputs a constant voltage which was previously the PID output signal. At the same time the difference between this constant voltage and the actual PID output voltage is fed as a new error signal to the PID input. * The S&H feature can be enabled / disabled via TTL. If disabled the output returns to zero on disable. * PID B returns to zero on disable using the same mechanism but without the S&H feature. * all digital inputs are optocoupled * all analog inputs are differential * the MOSFET out can drive high capacity * the PSU output is limited to 0-10V ==== Schematic ==== * All files can be found on http://bibo/git/CurrentStabilisation.git * {{ :eigenbau:current_stabilisation.pdf |Schaltplan}} in PDF-Format * Die Source des Schaltplans ist auf der [[eigenbau:src:sourcen|Download-Seite des Wiki]] abgelegt. ==== Layout ==== * PCB size: 160 x 100 mm /* Höhe mal Breite in mm */ * Supply: > +/-15V * Inputs: * Ultrastab (D-Sub) or Current/Voltage (BNC) * control voltage to set the current, * TTL enable * TTL enable S&H * TTL interlock * Outputs: * current monitor * error monitor * PSU control * MOSFET control * Displays: none * PCB population plan: {{:eigenbau:currentstabilisation:current_stabilisation-brd.pdf|front}}{{:eigenbau:currentstabilisation:current_stabilisation-brd_back.pdf|back}} * Die Bestückungsliste: * Die {{:eigenbau:current_stabilisation_v1a.zip |gezippten Gerberdaten}} für die Bestellung der Platine * Die Source des Layouts im pcb-Format liegt auf der [[..:start|Download-Seite des Wiki]]. FIXME /* Das Layout als gerenderter Export vom EDA-Programm [{{?400|Layout (Oberseite)}}] */ ==== Housing ==== In progress, Hammond for 160*100 mm, Height? FIXME /* Welche Kiste mit kurzer Begründung, warum gerade diese */ /* * Die Source der Konstruktionszeichnung liegt auf der [[:eigenbau:src:sourcen#currentlimit|Download-Seite des Wiki]]. * Die {{:eigenbau:currentlimit:currentlimit_box.pdf|Konstruktionszeichnung des Gehäuses}} im PDF-Format. */ ==== Test ==== Up to now only PID A is populated (exept D) after Hacking the logic at the S&H IC, it works as expected. after switching in hold mode, the current seems to be a bit lower than the initial setpoint. this might be caused by the big hold capacitor. Maybe after 0.5 sec. it is not entirely loaded. The hold time seems to be huge, after 30s there is almost no change visible, seems to be a fraction of a Millivolt. So it might be an option to change the Cap to a smaller one, leading to a smaller hold time, but a more precise hold value. The idea of having the current on for a longer time before switching to hold mode didn't really help, so it doesn't seem to be an problem related to the loading curve of the hold cap. after a hold time of ~4 minutes, the current monitor voltage dropped from ~39.6 mV to 39 mV. FIXME /* Welche Signale sollten wo zu sehen sein? */ ==== Usage ==== === Input Signals === ^ Input ^ Type ^ Description ^ | ULTRASTAB (D-SUB) | analog current (differential) | current input from current transducer,\\ can be modified to differential voltage input. | | Current set | analog voltage (differential) | current setpoint | | enable | digital voltage (optocoupled) | high: PIDs enabled, outputs active\\ low: disabled, MOSFET out turned to zero. | | S&H | digital voltage (optocoupled) | high: S&H active, PID A holds voltage on disable\\ low: S&H diasbled, PID A returns to zero on disable | | interlock | digital voltage (optocoupled) | high: device operational, \\ low: all outputs off, PIDs return to zero | === Jumper Settings === ^ Jumper # ^ Feature ^ options ^ | 1 | Current monitor output reference | pin 1 (right): normal gnd\\ pin 3 (left): clean gnd | | 2 | MOSFET output selection | pin 1 (right): PID B (without S&H)\\ pin 3 (left): PID A (with S&H) | | 3 | Enable Input usage | pin 1 (left): connect enable in\\ pin 3 (right): connect to gnd, permanent enable | | 4 | ULTRASTAB interlock usage | pin 1 (top): ULTRASTAB interlock used\\ pin 3 (bottom): ULTRASTAB interlock ignored | | 5 | External Interlock usage | pin 1 ( left): ext. interlock used\\ pin 3 (right): ext. interlock ignored | | 6 | Sample and Hold usage | pin 1 (bottom): S&H input connected\\ pin 3 (top): S&H permanently enabled\\ No Jumper: S&H permanently disabled | FIXME /* Was beim Einsatz zu beachten ist. Eventuell mit Anweisung zur Inbetriebnahme. */ ==== Bilder ==== /* Photos vom Gerät. Wenn möglich und sinnvoll Nahaufnahmen von der Platine. Die Bilder sollten in einem Unterordner "bilder" zum Projekt untergebracht sein. Beipiel für den Aufruf einer Bildergalerie: */ {{gallery>:eigenbau:currentstabilisation:pictures?lightbox&showname&4 }} ==== Kalkulation ==== FIXME /* Der Aufwand pro Gerät (Materialpreis, externe Fertigung, etc) */ ^ was ^ wieviel ^ E-Preis ^ Preis ^ Anmerkung | | Leiterplatte | 1x | ??.?? € | ~~=round(cell(1,row())*cell(2,row());2)~~ € | 1/n von XXX EUR | | Gehäuse | 1x | ??.?? € | ~~=round(cell(1,row())*cell(2,row());2)~~ € | | | * | ?x | ??.?? € | ~~=round(cell(1,row())*cell(2,row());2)~~ € | ... | | R,C | ??x | 0.02 € | ~~=round(cell(1,row())*cell(2,row());2)~~ € | Bauform 0805 | | Bestückung | ??.00 € ||| bei SRM | | [[:eigenbau:Verschnitt]] | ?.?? € ||| | ^ Summe ||^ ~~=round(sum(range(3,1,3,row()-1));2)~~ € | | ==== Meckerliste ==== Was für die nächste Version zu tun ist: (:no:: verworfen, :Ok:: in Arbeit, :ok:: im Schaltplan, aber noch nicht im Layout, :OK:: erledigt) * :OK: Logic at S&H is wrong. On prototypes (v1a) it can be hacked (pins 10 & 11 have to be interchanged). * :OK: add values for Zener diodes * :OK: add diodes across voltage regulators to protect them * :OK: 5V regulator is TS78L05ACY pinout (out - gnd - in) * :OK: change Mosfet ouput stage to twice noninverting. negative offset added on the nagative input of frist OpAmp, such that the MOSFET pulldown works * :OK: add footprints for IC shields for instr. Amps and sum * :OK: larger cutout for XLR Power input * increase through hole sizes (hard to unsolder) * :OK: supply capacitors laying on rear side * :OK: interlock status leds * :OK: add second ref footprint parallel in current set path for more gain flexibility