Which power supply for my stepper motor

Hi guys,

I work on a project where I have to use a peristaltic pump to add nutrients to a reactor.

My pump: B150 ODM Peristaltic Pump - Lead Fluid Technology Co., LTD

I read some article about the control of a stepper but I wanted to be sure about the power supply and the motor driver use.

  1. Normally, when you choose your stepper, you need to determine the torque available. In my case, because I buy the motor directly with the pump head, I suppose that the torque produced by the motor enables me to drive the pump. Is it good?

  2. To drive the stepper, I need a shield. Because the phase current is 2A, I’m looking for a shield of 3A to be sûre to have enough amp. I choose a TB6500 (https://www.makerguides.com/tb6560-stepper-motor-driver-arduino-tutorial/) to control the motor.

  3. And now here is my problem, I don’t understand which supply voltage I need. Now, I use a 230/24 adapter (https://fr.farnell.com/traco-power/txl-060-0534ti/alimentation-metal-60w-24v-1-2a/dp/1284185). 24 VDC is enough for this motor?

  4. I prefer to precise. I need a pump working h24 7j7. For the moment I choose a stepper but I know that I brushless is better for this concept but it’s difficult to found a peristaltic with a brushless in this low flow range.

Thanks for your time,

Kind regards

The supply voltage is less relevant. What is relevant is the coil current. You will set the coil current limit on the stepper driver. 24V power will allow higher speed than 12V.

Thanks for your answer,

So for you the setup is good ?

A

The power supply says 24V 1.2A. Not enough current capability for a 2A per phase stepper. I would get a supply capable of at least 3A. More for the cheap Chinese parts, they can over rate their stuff.

Apart from the price and the power consumed, is there a disadvantage to using a supply with a high current phase?
For example, If I found a 24V/10 A.

More current is fine. The driver will limit the current to each phase (coil) if the coil current limit in the driver is set properly. Having more current capability is actually a good thing.

The power consumed by a 3A or a 10A power supply will be nearly the same if supplying the same current all other things being equal.

Not operating a device near its limits will extend the life of the unit so more current capability is a good thing.

How about the role of TB500 plays the control of voltage and current

Hi,

Thanks for your answer groundfungus. That all I wanted to Know.

I have an other question for you and I tkink you Can have the answer.

In Arduino méga (controled by a raspberry) , I have to control maybe 3 to 4 Pump and around 10 solénoid valve (and many sensors but I think that I will use an other mega only for the sensors).

To size my supply voltage, I think that I have to sum the max consumed current of each Pump/valves and to add some amps to be secure.

It’s correct ?

Vishkas :
Sorry I don’t understand your meaning. The TB500 enables us to size the current/voltage whereas the TB6500 works only with the current ??

Sorry I’m a beginner and french :joy: my english is not really good

You will need more than one voltage. 5V for the processors (Mega), 24V for the steppers, what ever the voltages are for the solenoid valves and sensors. Then you will need to know the current that each voltage supply must be capable of supplying by adding up the currents.

You will need drivers for the solenoids, like transistors, Arduino pins will not drive solenoids.

Consider IO expanders to get more IO pins instead of another Mega. Adding another Mega can be rather complex. IO expanders like I2C expanders (MCP23008, MCP23017) or shift registers (HC74HC595) can give you lots of digital GPIO pins.

Oh thanks, I didn’t know the shift registers system. I will check this more in detail.

My system will be composed of 1 to 3 pump 24VDC, maybe 10 electrical valves in 12VCD or 24VDC (more 24 than 12) and I don’t know the exact number but maybe 30 sensors (flow meter/temperature sensor/differential pressure/lux…) Most of all in 5VDC I hope.

So I had already thought of using two external power supplies, one for the mega and the sensors, and one for the motors/valves.

For the pumps, TB6500.
For the valves, I imagined using a shield motor, the same type of shield with which you control DC motor. For example, in a moment I wanted to use the adafruit motor shield V2 (Overview | Adafruit Motor Shield V2 | Adafruit Learning System) because it is easy to use and you can stack one shield to another (I love this feature) but it’s just 4.5VDC to 13.5VDC, not 24VDC.
An option is to use only 12 VDC valves but I wanted to have only one circuit in 5V and one in 24, not 5/12/24.

(And the raspberry is for the data processing and the wifi/mqtt connection).

In any case, thanks for your answer! It helps me a lot

Untrue. The pump motor is 2 ohm, 2A, so uses 8W, and a 24V 1.2A supply can provide nearly 30W, so its perfectly adequate for one or even two pumps.

The current through the motor windings is not the same as from the supply with a stepper driver.

Hi Mark, can you develop this sentence? Or have you any source?

A.

A current driver works similary to a buck switching regulator. Here, too, the current at the output is higher than at the input.
The difference is, that it doesn’t regulate the voltage at the output but the current. And it uses the coil of the stepper as the inductance, while the buck regulator needs his own inductance.
However, it should be noted that usually both coils are energized. The necessary power is therefore twice as high (16W instead of 8W in this case).

Thanks MicroBahner and Markt,

Now I know how to calculate the P with only the number of phases and the phase current.

As I said here I will add some parts :

My system will be composed of 1 to 3 pump 24VDC, maybe 10 electrical valves in 12VCD or 24VDC (more 24 than 12) and I don’t know the exact number but maybe 30 sensors (flow meter/temperature sensor/differential pressure/lux…) Most of all in 5VDC I hope.

So I have bought a large power supply in 24V with big amps (the link is at the bottom). I will buy an other supply only for the 5V.

(https://fr.rs-online.com/web/p/alimentations-a-decoupage/1618270/?relevancy-data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searchHistory={"enabled"%3Atrue})

But keep in mind that this is only a rough estimate. The efficiency of the driver, and the mechanical work that the stepper must do, must also be considered. But 30 W is still almost 2x the estimate and should therefore be sufficient ( for one stepper ). It is also important to have a sufficiently large buffer capacitor at the supply terminals of the current driver.

Where is the buffer capacitor ? In the supply or in the motor driver ? I don’t understand this part.

Untrue, trust me I know about steppers. A 2A stepper takes 2A through a coil when only one coil is energized, 1.4A each when both coils are energized equally, and in general the
two coil currents Ia and Ib will be such that Ia^2 + Ib^2 = 2^2. Thus the total power is 8W
if the coils are 2 ohms. The currents are in quadrature.

You might want to read a few datasheets for stepper drivers, for instance section 8.3.2 of
the DRV8825 datasheet: https://www.ti.com/lit/ds/symlink/drv8825.pdf?ts=1620028189216&ref_url=https%253A%252F%252Fwww.google.com%252F

Note the big table shows all the currents as a percentage of the full scale current preset by the Vref pin.

Yes, sorry, my fault. I mixed up with voltage controlled steppers in full step mode. I know theses stepper datasheets .

This bulk capacitance is needed as close as possible to the powerpins of the driver ( this is also written in the datasheet :wink: ). It is a central component of the driver, and the full coil current does indeed flow between the bulk capacitor and the driver.

This bulk capacitance is needed as close as possible to the powerpins of the driver ( this is also written in the datasheet :wink: ). It is a central component of the driver, and the full coil current does indeed flow between the bulk capacitor and the driver.

How I can estimate the capa ? Is there a formula ?

In type of driver, usually poeple recommended to me the polulu driver but is there pololu which can enables me 2A in continuous ? And again, is there a equation to size the driver ? For example I bought this morning a peristaltic pump with a stepper motor which has a phase current of 0.86 A only but the datasheet says to use a 2Amp driver.

X2 is a very large safety no ? 2A do not enable me to use Polulu. I bought a DRV8825 because I want to “test” with a 1.5 Amp driver but without the DRV8825, there isn’t any Pololu for hight current. The only driver taht I know which works in average of 2amps is the TB6560. Do you know any models between the two ?

Hi,
Did you purchase the

B150 ODM-A
OR
B150 ODM-B (with controller PCB)

Thanks… Tom… :grinning: :+1: :australia: