Part Number: MCF8329EVM
Other Parts Discussed in Thread: MCF8329A
Tool/software:
We have an MCF8329EVM connected to a BLDC motor with no load. The motor is 24V, 7.29A rated current. We have filled in Sections 1 & 2 in the Motor Studio GUI (version 1.34) but every time we run the Smart Tune function, it results in the message "Configuration Failed". Nothing we do changes this outcome. The motor is a Maxon 625858.
One thing we found is the set-up instructions for the EVM tell you to set the speed potentiometer to the full clockwise position (in the text) but the picture shows an arrow turning the potentiometer anti-clockwise. If we set the pot to the full anti-clockwise position we can then get the motor to spin, where as it won’t spin in the full clockwise position. However, the Smart Tune still fails.
The settings we have made are as follows:
Section 1, “Basic Information”
- “No Load” selected – we don’t have any load connected to the motor
- Rated Voltage set to 24V – this is correct for this motor (in our product we will use a 48V motor, but we don’t have one of those yet)
- Rated Current = 7.29A from item 6 in the motor datasheet
- Rated Speed = 700Hz calculated from the motor datasheet using max speed = 6000rpm (item 23) & the number of pole pairs = 7 (item 29) . 7 pole pairs = 14 poles.
Using your formula Speed in Hz = N x P/120 = 6000 x 14/120 = 700Hz - Control Mode is set to “Speed Mode”
Section 2, “System Parameters”
- MCF8329x Shunt Resistance = 1mW from MCF8329A documentation
- Motor Phase Resistance = 0.288W from item 10 in the Motor datasheet
- Motor Phase Inductance = 0.279mH from item 11 in the Motor datasheet
- Back EMF Constant = 47mV/Hz calculated as follows from the Motor datasheet values
Speed constant = 182rpm/V (item 13) from Motor datasheet
Back EMF Constant = (1000/Sped Constant) x (120/P) = (1000/182) x (120/14) = 47mV/Hz
We have tried changing various parameters (eg 7 Pole pairs instead of 14 poles), but nothing seems to work. Any ideas?
