Back EMF File [JSON]

The shape of the back EMF waveform for a PMSM BLDC or 6-Phase PMSM BLDC machine can be customized using a JSON file. In the configuration page for the machine, set Back EMF Profile to User Defined and point to the Back EMF JSON file in the Back EMF File Path field. Click Preview to display a graph of the waveform.

The file must contain the following information:

Parameter (JSON key)	Data Type	Description	Example

Parameter (JSON key)	Data Type	Description	Example
backEmfValues	double[1024]	One-dimensional array of gain values representing a single 360-degree period of the back EMF waveform. The array must contain exactly 1024 values ranging between -1 and 1.	`"backEmfValues": [ -0.0, -0.005, -0.01, […] 0.01, 0.005 ],`

Examples

Three example Back EMF files are attached as a reference:

backEmfSinusoidal.json implements a sinusoidal waveform similar to the default back EMF shape of the PMSM Constant Ld/Lq and PMSM Variable Ld/Lq machine models.
backEmfTrapezoidal.json implements a trapezoidal waveform similar to the default back EMF shape of the BLDC machine model with a Back EMF Flat Area of 120°.
backEmfModifiedSine.json implements a customized sinusoidal waveform.

Note that the default sinusoidal and trapezoidal profiles are scaled by a factor of to convert line-to-line RMS values into line-to-neutral peak values.

backEmfSinusoidal.json

backEmfTrapezoidal.json