Switching Frequencies for Industrial/Automotive Solid State Relays

Community General Discussions
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I have been working on a large outdoor robot driven by “Power Wheels” children’s car motors for a while now (http://boomsandbots.blogspot.ca/search/label/Project%20Killzone is the section of my blog devoted to it) and I decided to build my own high power motor controller rather than buy one. As you can imagine, it has been a journey filled with smoking electronics, learning, and rebuilding. Anyway, I have relays set up to control the direction of the motors, and that part works quite well, but the problems I have had is with the speed control section. I have tried plain MOSFETs a couple times and ended in failure each time, so I turned to looking for high power solid state relays. Some googleing around lead me to these two relays which seem the most promising:

http://www.amazon.com/Single-Phase-Solid-3-32VDC-5-110VDC/dp/B009AQN9CQ/ref=sr_1_3?ie=UTF8&qid=1403295790&sr=8-3&keywords=Solid+state+5-60v+relay

My question is if anyone here has used these style of solid state relays, and if they can handle the fast switching frequencies required for PWM speed control, or if there is some speed limitation that would make these totally unusable for such an application. Not just those particular models, but that style of either automotive or industrial type SSR.

Sorry if that is a stupid question, and thanks in advance for any help.

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Thanks :slight_smile:
Bdk6, you are a man of few words, and very helpful, thank you. I appreciate the links :slight_smile:

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See, this is why I ask :slight_smile:
Thank you for clairifying much more Bdk6, and thanks for the other comments Oddbot and 6677, I very much appreciate all the advice given.

Bdk6, I am aware that the diodes in the schematic that I linked do nothing to protect anything from the motor, so far the relays have stood up just fine to the back EMF coming from the motors, tho I will do a lot more reading on this subject.

Thank you for the explination about all this, both you and 6677 have made this much clearer, I very much appreciate your explinations, you learn something new every day.

Oddbot, thank you for the tips about coding, I shall keep that in mind in the future, as well as the explination about the reverse diode built in, I knew about these, but was unaware that they are often rated lower than the FET itself.

I appreciate all the advice very much, thank you for taking your time to explain :slight_smile: LMR is a wonderful community.