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Hot!MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957)

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ASabir
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2015/03/02 11:40:01 (permalink)
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MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957)

Hi Fellows,
 
I recently purchased the MCLV-2 development board along with the AC300022 BLDC motor. However, I was expecting to achieve the trapezoidal 'two-phase-on-at-a-time' control scheme on this setup. However, upon looking at the datasheet of the motor, I realized that its back-emf is sinusoidal. I am greatly worried, since I absolutely need to implement trapezoidal control for my research.
Is it possible to run the sensored control on this setup as described in the application note AN957? Any first hand experience or advice on this topic will be greatly appreciated.
 
Regards,
Sabir
 
P.S. The motor datasheet available here:

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    WB
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/02 14:14:58 (permalink)
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    Hi Sabir,
     
    You will find that most motors labeled as BLDC have a sinusoidal BEMF. The AC300032 motor works very well with the trapezoidal drive, as do all 3-phase motors with sinusoidal BEMF.
     
    WB
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    ASabir
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/02 16:08:04 (permalink)
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    Thanks for your input, WB!
     
    The documentation of MCLV-2 guides you through running the 'Sensorless Control of PMSM' (as in application note AN1299) on the AC300020 motor. This motor pretty much the same as AC300022 except it has low resolution Hall effect sensors. 
    So if I were to run, say, the 'Sensorless BLDC control' as in AN957, using AC300020 motor, all I need to do is just run the source code of the application note AN957 on MCLV-2 with AC300020, and it will run the motor under trapezoidal control?
     
    Having this assurance will really solve my problem!!!
    #3
    WB
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/02 16:48:17 (permalink)
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    AN957 discusses sensored BLDC control. Both the AC300020 and AC300022 motors have the necessary Hall sensors to operate as sensored motors. Either motor will operate with trapezoidal drive. You will need to connect the three motor phases, the three Hall outputs, and Hall supply lines to the MCLV-2 board. The Hall sensor connections must coincide with the way the three motor phases are connected. The right combination is code dependent. It may take some trial and error to get the connections right. When it's right you will see a trapezoidal shaped waveform at each of the motor phases when the motor is running. When it's not right the motor will either not run at all with very high current or run erratically with higher than expected current.
     
    WB
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    ASabir
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/03 01:50:56 (permalink)
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    Thanks for this much needed clarification!
     
    Now, in case the Halls are not connected in the correct sequence, can that high current damage the motor by any chance?
    Any precautionary advice to ensure the equipment safety?
     
    Regards,
    #5
    WB
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/03 08:38:24 (permalink)
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    I assume you will be using PWM drive to control the motor speed. If you keep the PWM duty cycle below 20% until things are sorted out you should be OK. You could also use a current limited power supply. That said, the motors you mention are pretty robust so I wouldn't worry too much about damaging them.
     
    WB
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    ASabir
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/04 00:48:01 (permalink)
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    Thanks again WB! grin: grin

    Acutally I am pretty new to the hardware implementation. I've done lots of MATLAB/Simulink. But just getting into C programming. As a starting point, I plan to get a source code from Microchip website, and then reverse engineer it to see how the commutation sequence works on these motors. I reckon that you have worked with these motors or similar applications.
     
     
    If you know of any source code with an application note that works on these motors,  can you point me in that direction?
     
    Regards,
    #7
    cbarn24050
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2015/03/04 09:29:16 (permalink)
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    Hi, the code on the note should work fine for your motor. It also explains how the commutation works, so no need to reverse engineer it. It is a rather crude implementation you should expect similar performance as you would get with a battery and a dc motor such as you would find in a toy train. TI have a lot of app notes on motor control you might read some them.
    #8
    btremaine
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    Re: MCLV-2 with AC300022 for Sensored BLDC Control (as in AN957) 2019/11/19 07:30:34 (permalink)
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    I realize this is a very old thread but your comment that AN957 is a crude implementation caught my eye. If you needed to run a sensorless BLDC in an application requiring low jitter @1800rpm what technique would you suggest? I've been looking at AN1305 and AN1160.
     
    Thanks,
     
    #9
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