Hello to all readers.
More than 7 years ago I did occupy myself intensely with stepper motors and with Trinamic modules. Using their stepRocker module and their IDE I was able to do many experiments to understand the implication that the Trinamic IDE made available to me controlling a stepper motor. I did use this combination of a stepper motor and the stepRocker module as part of my efforts to implement a winch to control the sail of my sailboat model. From the stuff that I learned then I am confronted with poor knowledge of stepper motors and with one of the consequences being to choose the wrong stepper motors. When myself trying to be polite addressing topics in this context I met aggressivity and comments that attacked me on a personal level. I hope this will be different here. And I want to explain why stepper motors today seem to be wrongly chosen and operated resulting in unnecessary step errors.
Let me go step by step:
The torque a stepper motor can deliver is dependant on the power with which it is fed. I know that this is only one parameter. I will come to others later.
To use numbers I want to use the standard power equation:
P[W] = I[A] * U[V]
Let's assume a printer is fed with the voltage and the current it is specified with. I call the nominal values.
P[W] = I[A] * U[V] = 1A * 12V = 12W
The critical factor in this example is the nominal value for the current, as this is related to the ability of the coils in the motor to how much current can flow through them.
Let us choose a different stepper motor with the same intake of power and in consequence the same torque:
P[W] = 4A * 3V = 12W
This is the better motor as its coils can be fed with 4A of current and achieve the same torque but with only 1/4 of the voltage means 3V!
Let us address the means by which Trinamic controllers control the feeding of a stepper motor. PW, Pulse with modulation. I am sure many of you know this. It is for those not familiar:
This graphic shows a PWM with 3 different settings for its duty cycle. Trinamic ICs control the current that flows through the coils of a stepper motor by changing the length of its duty cycle. So if you operate a stepper motor with its nominal values a duty cycle of 100% means the current flows continuously through the coils. But what does the Trinamic IC when you operate the second stepper motor, not with 3V, but with 12V? It sets the duty cycle to 25%. What is the result of this? The current that flows through the coils is still 4A:
P[W] = 4A * 12V = 48W
Thanks to the Trinamic IC, it limits the current to the 4A, its nominal value by using PWM at 25%. Now that second stepper motor has 4x the torque.
So whenever I choose a stepper motor for one of my naval modeling boats I choose the one that has the smallest nominal value for voltage as this way I have the maximum torque available. In my model sailboat, I feed my stepper motors used as winches for the control of the sails have a 3.6V nominal value fed by 12 LiFePO4 batteries. This battery pack when fully loaded delivers close to 40 V and when empty and they have to be recharged it is 24 V. So all SilentStepSticks based on Trinamic ICs offer this functionality.
So why it seems Creality i.e. uses nema17 in my Ender 5 Plus and specifies them to be 12V?
When I study YouTube Videos, i.e. the Kersley Fabrications channel I learn that one of the reasons to limit the printing speed is due to loss of steps. When I learn that the linear mode to accelerate and reduce speed is to be preferred over the S-Shape mode. If the NEMA 17 stepper motors used in my Ender 5 Plus are specified for 12V then the Trinamic IC is already using its PWM when the motor is fed with 24V. Of course, also the ability of the controller on the control card has to have the performance to do its computations. The higher the performance of the controller, the higher speed the printer can print while keeping the ability to do its control job.
It is topics related to this that made me choose the BIGTREETECH-SKR-PRO-V1.2 controller board. It has an ARM Cortex M4 controller that is already or powerful in its computation abilities and the higher operating frequency, 168MHz adds to it. The other reason I choose this board is that it supports SilentstepStick5160 and 5160hv. The TMC5160hv makes it possible for the SilentStepStick5160hv to feed the stepper motor with up to 50VDC, in the datasheet even 60VDC are mentioned. I have purchased a Meanwell 600W 48 VDC power supply and 6 SilentStepSticks5160hv from Watterott, the German company that partners with Trinamic, also a German company.
You might understand now why I was so surprised, not to be aggressive as Germans often are, that even the support of BIGTREETECH seems to be ignorant about this. I have already sent 3 emails to their support to ask if when applying 48VDC to their "Motor Power" connection these are isolated from other parts of the circuitry of my board. Still, just the response that the board can only be fed using either 12VDC or 24 VDC. Sure, and I am aware of this, the circuitry in this board can only be fed with one of these 2 possible voltage values.
Does anyone of you know if the Motor Power connectors are only passed to the VM of the sockets for the SilentStepSticks?
