Frequency Control

mikeyh · 2018-05-29 05:51:26

Hi All,

How do I use the Monarco Hat to frequency control an inverter drive for a motor?

- I require a fixed a duty cycle of 30 to 70%
- maximum voltage of 15Vdc
- minimum on state voltage of 4Vdc
- maximum off state voltage of 0.7Vdc

The inverter drive uses a control frequency of 0 - 150Hz (0 - 4500 rpm)

I have used duty cycle on the Monarco before, fixed at 1Hz. How do I do variable frequency?

Thanks

Mike

jaroslav_sobota · 2018-05-29 09:24:52

Hi Mike,
thanks for your question. You should be able to connect the Monarco HAT DOUT directly to the inverter drive. The internal pull-up to 5V will do the job. As for controlling frequency, see the example project 0121-05 on using Monarco HAT PWM outputs. You can find it in our GitHub repository of example projects.

Please let me know if the example covers the topic well and if it works for you.

Kind regards,
Jaroslav

mikeyh · 2018-05-29 10:14:59

Hi Jaroslav,

Thanks for the reply.

So correct me if I'm wrong! (MNR__PWM1_Frequency) sets the required, 0 - 150Hz and (MNR__PWM1A) will set the fixed duty cycle for the same output channel?

I assume if using a PID controller the output scale just needs to match the required frequency?

Thanks

Mike

jaroslav_sobota · 2018-05-29 11:27:40

Yes exactly. Just keep in mind that the PWM1_Frequency is common for DOUT1, DOUT2 and DOUT3. Therefore you can only control 2 such drives using a single Monarco HAT.

Also keep in mind that the lower limit for frequency is 1 Hz. To turn off the output completely, you'll need to set duty cycle to 0.

If necessary, use the GAIN, LIN or CNDR blocks to scale the PID controller output (e.g. 0-100%) to frequency (0-150Hz).

Jaroslav

mikeyh · 2018-06-07 20:32:53

Thanks Jaroslav, works like a charm.

jaroslav_sobota · 2018-06-08 11:38:38

Hi Mike,
glad I could help. To be honest, I discovered several issues when preparing the PWM example. These are now fixed and the new version v2.007 of the Monarco HAT firmware has been released. See https://github.com/monarco/monarco-hat-firmware-bin

I highly recommend upgrading your Monarco HAT to this version.

Kind regards,
Jaroslav

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#1 2018-05-29 05:51:26