12V DC motor high speed dithering with Compac Daq Solid State Relay module

[RC007]

I am working with small DC motors that operate at 12V, Current draw between 10 and 500 mA.  I was wondering if anyone has ever tried high speed dithering (polarity switching) using a Compac Daq Chassis with a Solid State Relay module?  If so, what type of performance can I expect (switching speed)?  Thanks!

[Matthew_W]

 Hi RC007,

 Are you referring to PWM using the cDAQ 9485?

 The manual can be found here. The switching speed (90% duty cycle) of this device is 1Hz.

 Have a great afternoon,

 MatthewW
 Applications Engineer
 National Instruments
 

[RC007]

Thanks, but that's not exactly what I'm looking for. 

Operation of the 12V DC motor for this test is as follows:

 1 Dither cycle =

 50 ms ON CW

100 ms OFF

 50 ms ON CCW

100 ms OFF

 

At this speed of switching you will only "Dither" the motor, but will not really see any significant travel.  I am thinking high speed solid state relay module with a long life (3 million dither cycles).  Any thoughts from your side?  Thanks!

[Matthew_W]

 Hi RC007,

 Thank you for the description of motor dithering, I had not heard of that before.

 The NI-9485 has a closing time of 9mS, opening time of 0.5mS when used within the specifications listed as: -40 to 70 degrees Celsius.
 If you have a lower current requirement or operate at a fixed temperature then the open/closing time will change as well.

The MTBF of this device is 2,172,740 hours as stated on page 14 of the manual.

Here is more information, there is a chart where you spec the current and ambient temperature then read off the switching speed.

Please post back if you have more questions regarding this application.

Best regards,

MatthewW
Applications Engineer
National Instruments

Message Edited by Matthew W on 08-01-2007 03:28 PM

Message Edited by Matthew W on 08-01-2007 03:33 PM

[AnalogKid2DigitalMan]

Have you devised a method yet on how to change the polarity of the voltage going to the motor?