Series or Parallel connection

[lensman57]

Hi again,
I need advice as to which way to connect up the motors please.
The motors are 1.89 NM 8 wire units and can be connected as either Bipolar series or parallel.
In series the current requirement is 2.1A per phase with an inductance of 6.4 mH and resistance of 2 Ohms, if connected in parallel it will draw 4.2 Amps but with an inductance of 1.6 mH and resistance of 0.5 Ohms. I have limited the current of the TB6560 driver board to 75% of its nominal max of 3 Amps for safety ie: 2.125 Amps.
Could I just connect the motors in parallel even though there is not enough current flowing through the board or just opt for a series connection and let driver deal with the high inductance.
I know it is easier to drive the motors if connected in parallel due to very low inductance but could the lack of current reduce the performance unacceptably or drive the board in to melt down ?
Any help is welcome.
Best regards,
A.G

 

[Tin Falcon]

if you wire the motors to draw 4 amps and the board is rated for three you will likely fry the board.
Tin

 

[RonGinger]

if you wire the motors to draw 4 amps and the board is rated for three you will likely fry the board.
Tin

Not really. The controller has a set value, and it will not exceed that setting- its a chopper and it turns on and off while measuring the current. When it reaches the set current it shuts off.

No damage to the motor, but it will not perform as well as it could. With lower current it will have lower holding torque. Operating at a lower voltage will cause the top speed to be lower.

 

[Tin Falcon]

ok so I stand corrected.
Tin

 

[Noitoen]

I think it´s the other way round. If you connect the motor parallel, for the lower voltage, you get higher speeds because the voltage/frequency curve of a motor is linear. The holding torque at lower speeds will be smaller.

 

[Troutsqueezer]

Two 2 Ohm resistances in parallel results in 1 Ohm resistance, not .5

I'd have to agree with Ron, lower voltage/Imax = lower speed/torque.