PMAC SINE WAVE

[jgil]

Posted on January 29, 2009 at 08:41

PMAC SINE WAVE

[jgil]

Posted on May 17, 2011 at 10:15

Hello.

I´m using a control of PMAC SINE WAVE with closed loop control and three hall sensors. I am using the kit of development AK-ST7FMC of softec microsystem and the application and the library an1947. We have a problem with the waveform of the current at two phases of the motor. Having this form o sine wave, but with an irregularity in a segment of the wave. Coinciding with two flanks of detection of the hall sensors. This We have try to set the optimum Phase Angle , but the problem is kept.Only it moves across the sine wave. Can you say me something of this problem? Thank you :o

[jgil]

Posted on May 17, 2011 at 10:15

Hello.

Thank you for the response. Finally the problem was a mechanic of positioning of the sensors inside the estator of the motor. Thank you :)

[gianluigi]

Posted on May 17, 2011 at 10:15

Using three hall sensors the phase synchronization will be performed each edge of each sensor so 6 times for each electrical period.

The assumption is that the three hall sensors are equally spaced. 120° or 60°. So the syncronization point have been set to these values: #if (HALL_SENSOR_NUM == 3) const u16 PhaseVal[]={0,10923,21845,32768,43691,54613}; Consider one electrical cycle equal to 65536 so each edge will occur each 10923 (65536/6) But if the sensor is not equally spaced the phase sinchronization can be correct for one sensor and fails for the other two. The phase angle will act by the same ammount for all of the six point so if you have the sensor not equally spaced you can not correct it using a single phase angle. You can try to change the Phase Val array for instance the elements [1][2][4][5]. You can keep [0] and [3] with the standard values and change the other in paris [1] with [4] and [2] with [5] Other possibility can be using three different Phase angle. PS. Are you sure that the sequence of the Hall sensor signal is the one expected (See AN1947) Best regards Gigi