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Calculate SimonK BLDC timing parameters

Recent releases of SimonK tgy.asm allow specification of motor timing as a combination of a fixed number of electrical degrees and a fixed time in µs.

This calculator calculates combination of MOTOR_ADVANCE and TIMING_OFFSET to give a linear advance characteristic that passes through two specified points.

One strategy might be to choose an optimal advance for maximum power at reasonable current, and advance for least current at hover or cruise RPM.

After changing motor timing, test the loaded motor thoroughly, including rapid acceleration and deceleration, looking for any tendency to lose sync. Sync recovery process can consume high current, so as always, initial tests on a current limited power supply are advised.

Inputs:      
  Poles    
Max power: RPM Equivalent advance (°)
Hover: RPM
Equivalent advance (°)
     
Results:    
MOTOR_ADVANCE (°)    
TIMING_OFFSET (µs)    

The calculator does not do a lot of error checking, if you enter nonsense, it will produce nonsense. If you get negative MOTOR_ADVANCE value, the result you want is not supported by the firmware.

Example

For D2830/11 with 8045SF on BS20 on an earlier release of SimonK, I specified:

 
Fig 1:
http://static.rcgroups.net/forums/attachments/4/7/7/7/3/4/a6045323-172-Clip%20065.png

Fig 1 shows the composite timing arrangement as either a time equivalent or degrees equivalent. The specific settings are equivalent to 20° at full power, and about 15° at hover speed. (The graph is specific to the motor configuration... the number of poles.). This gives good max power, and about 10% reduction in current at hover... so close to 10% better battery endurance.

Links

Changes

Version Date Description
1.01 15/08/2013 Initial.
1.02    
1.03    
1.04    
1.05    

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