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| Question on DC motor current measurement |
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| XaviPacheco:
I have a previous thread about this, but I dropped the topic for a while. I'm using this current sensor TLI4970-D050T4 located at the emitter leg of a power IGBT, which is being switched at 5 kHz. It's a low side switching configuration, i.e, motor at the collector leg. The sensor has the default parameters according to the datasheet. I'm thinking of triggering an external GPIO interrupt every rising edge of the PWM signal, and sample the current at this point. Do you think it's a good idea? |
| MasterT:
Probably not a good idea. Fastest response time is 57 usec, period of the 5 kHz PWM is 200 usec, though at the best sensor could capture 30% PWM and up. What is more problematic, current is not a linear function, and slow sigma-delta adc is no-go with exponentially rising current. So, I'd say - no. |
| XaviPacheco:
The thing is that I'm trying to sample the current only when the transistor is ON. Do you suggest a better way? |
| MasterT:
Better is SAR adc. Sensor is shunt or hall, someting like acs712. What is uCPU, does it have an adc? |
| XaviPacheco:
--- Quote from: MasterT on October 31, 2018, 02:01:29 am ---Better is SAR adc. Sensor is shunt or hall, someting like acs712. What is uCPU, does it have an adc? --- End quote --- I can't change the sensor for now. |
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