I need opinions regarding MotionKing motors and 203v

[PEU]

Im building my second router and I'm still undecided on what motor to select, narrowed down the selection to 2 units from Motionking, both are Nema34 and 8 wires:


Electrical Specifications (UNI-POLAR):

34HS9801
Rated Current: 4.0
Phase Resistance: 0.98 ohm
Phase Inductance: 4.1 mH
Holding Torque: 490 N.cm Min

and

34HS9802
Rated Current: 5.0
Phase Resistance: 0.65 ohm
Phase Inductance: 2.4 mH
Holding Torque: 490 N.cm Min

Complete spec sheet for both motors

Per Mariss empirical formula of v(max)=32 x sqrt(inductance) the voltage of both motors are within 203V capabilities, so the question is more about the inductance.

Which one of these two motors would be more suitable for a 203V? my idea is to use them half coil as I will use a 4:1 reduction, but I'm open to suggestions on this matter too.

Thanks a lot in advance.


Pablo

[PEU]

anyone please?

[PEU]

am I transparent?

[Mariss Freimanis]

Nope, you're not invisible. I needed to put on my "see invisible people" glasses. I can see you just fine now.:-)

Motor #1 inductance is 4.1 mH. Motor #2 inductance is 2.4 mH. Both motors have the same holding torque which means both will have the same performance when driven with what they need. So, what do they need?:

Motor #1 has a maximum power supply voltage of V = 32*SQRT(4.1) or 65VDC
Motor #2 has a maximum power supply voltage of V = 32*SQRT(2.4) or 49VDC

Both motors will be identical in performance when driven with their respective maximum power supply voltages. Both voltages are within the specifications of the G203V drive. So how do you choose which one to use?

Model the G203V as a 0.25 Ohm resistor for thermal considerations. This will determine how big of a heatsink you will need.

Motor #1 is rated at 4A. I^2 * R is 4^2 * 0.25 or 4W of drive dissipation.
Motor #2 is rated at 5A. I^2 * R is 5^2 * 0.25 or 6.25W of drive dissipation.

Motor #2 will make the G203V drive dissipate 1.56 times more heat than Motor#1. At this point it seems Motor #2 is better; less drive heat, same performance.

But wait, there are other considerations. 49VDC is awfully close to 48VDC and there are very many inexpensive off-the-shelf 48VDC available. 48VDC is a standard voltage.

65VDC is not a standard voltage. You will pay extra and you will have a difficult time finding an economical 65VDC power supply. Meanwhile the 5A motor run from a 48VDC supply will generate 2.25W more (6.25W - 4W) heat in the G203V. This is a small difference. The G203V heatsink for the 5A will be only a little bit bigger than the one for the 4A motor.

If this was my problem? I would pick the 5A motor only because I could use a standard 48VDC power supply instead of a custom one. I would deal with the increased G203V heat by improving my heatsink. It would be cheaper solution than finding a 65VDC power supply.

Pick the 5A per phase motor.

Mariss

[PEU]

Thanks a lot Mariss!
Great explanation about what to consider when selecting a motor.

[guerd87]

Great info! I am too just about to choose my motors for a Mechmate Build. I was considering either the Motionking motors above (9801) or the Keling KL34H280-45-8A motors.

I might look into getting the 9802's

John

[Khalid]

Great info Mariss..Thanks..I ordered my G203V 04 drives a couple of days ago..any feedback?