Re: Power Supply for 4-axis CNC stepper driver

--- In CAD_CAM_EDM_DRO@yahoogroups.com, "Weedy" <weedy@e...> wrote:

> Hi, I need some help in constructing my Power Supply (my input

voltage is

> 220 VAC, 60 Hz) for my stepper drivers. Here are the details:
>
> Stepper Motors specifications (3 or 4 pcs., if optional 4th axis

will be

> installed):
> 2.4 VDC rated voltage,
> 6 A/phase rated current,
> 0.4 ohm resistance/phase,
> 3.4 mH inductance/phase,
> 4.2 N.m holding torque,
> 4 wires (bipolar)
>
> Stepper Drivers specifications (3 or 4 pcs., if optional 4th axis

will be

> installed):
> Output current - 7.8A max, 2.8A min,
> Supply voltage - 90 VDC max, 18 VDC min
> Microstepping - 2,4,8,16,32,64,128
>
> Since I want to construct my own power supply (PS), can someone

check the

> following calculations:
> 1) I want to go 25 times of motor rated voltage (2.4VDC), so the PS

output

> voltage (Vo) = 60 VDC
> 2) Transformer secondary voltage (Vt) = Vo/1.414 = 60/1.414 = 43 VAC
> 3) Going for 4-axis, current = 4 motors x 6A/phase x 2phase/motor =

48 Amp

> 4) Normal current draw being 66.67% of total current, so Current

(It) =

> 66.67% x 48 = 32 Amp
> 5) Transformer VA = VAC x It = 43 x 32 = 1376 VA
> 6) So, Transformer should be: Primary - 220 VAC, 1376 VA (Watts),
> Secondary - 43 VAC
> 7) Capacitor = (80,000*It)/Vo = 80,000 * 32 / 60 = 32,000 uF and

voltage

> 120% of Vo
> 8) So, Capacitor should be at least 32,000 uF, 72V or higher
> 9) Bridge rectifier at least 32 A, 72V
>
> If the above are correct, what are the commercially available

specifications

> for:
> 1) Transformer
> 2) Capacitor
> 3) Rectifier
>
> TIA!
>
> Weedy

Hi Weedy,

Have you considered using two or more power supplies? If you do,
you can easily build the power supply by buying two PMDX-135 power
supply boards, two toroid transformers from PartsExpress.com (Avel
Y236903, 40 + 40 800VA or Avel Y236907, 45 + 45 800VA might be a good
match).

The PMDX-135 has the proper caps, bridge rectifier, and bleeder
resistors, which means you won't have to search forever to find some
large caps.


-Mike