Does anyone have experience in the custom design of hybrid stepper motors?  Is there some software that can be used to generate their design?

Hi
their is some commercial sw such as SPEED that gives first designs that could plugged into some FE tools. limitations of such tools : it uses a library of parametrizable geometries (it is good for quick designs). however if you have more specific geometries go directly for FE ...

I do not believe that SPEED has a module for hybrid stepper design. Or at least I haven't seen any SPEED publications on this type of motor. I haven't seen any basic programs that can design a hybrid stepper beyond a rudimentary estimation of geometry. The flux leakage and 3D properties would make numerical estimation of performance very difficult. My colleagues that have worked on hybrid steppers have wound up going back to older design handbooks and then testing the designs with 3D FEA.

>David Farina : could you please give a good ref for a design handbook ?
* FEA will be very heavy for pre-designs.

>Douglas : depending on the selected geometry/Materials (symmetries/iso or anisotropies ... ) 3D FE calculation could be reduced.

I have looked at the Speed software but it seems to be written for brushless DC and brushed DC motor design using closed form solutions. It does not have modules and does not seem to be written for steppers motors. I will try contacting Bert Leenhouts however from what I have seen of his work he seems to focus on stepper motor controllers, not motor design. I will contact him anyway and see what he has to say. I have looked into JMAG and see that they have used their software for Hybrids and that I think is one possible solution however I was looking for some way to analyze the hybrid motors as a first order solution. It seems to me to be overkill to start with FEA. Ideally there should be something like Speed written for Hybrids, no?

You should think about the design but also manufacturing. We do a lot of design work but it usually involves some plan to move the design into production.

As for a design text, I will have to get that information from one of my colleagues.

As for a first order simulation: most designers that I have worked with rely on previously correlated measurement data that gives them an approximation for leakage and saturation. They can then apply this information to a new design.

Without the correction factors, you can make a performance approximation, but you would still need to test the model with 3D FEA to factor in all the non-linearities. So I haven't seen a program that can account for these factors without relying on FEA. At the same time, I am not a stepper expert, so there may be software packages out there that can provide a reasonable estimation of an initial design.

Mechanical constraints are also critical since air gaps are small. For me, it is similar to working with SR motors. Theoretical operation is governed by very nice equations, but actual performance is driven by non-linearities and mechanical constraints.

I have analyzed several hybrid stepper motors in the past. In all cases I had to use 3D FEA, in my case I use the MagNet software from Infolytica. Infolytica does offer a finite element based software for motor design called MotorSolve but it is currently limited to 2D motor like the SPEED software. As far as I know there are no design packages like MotorSolve or SPEED for 3D motor design.

So it seems like there is no way to do a first order closed form analysis (even if it is only within 10% or 15% accuracy) of these types of motors, is that correct? I have known some motor analysts that have had their own closed form models for hybrid motors.

With respect to FEA has anyone compared JMAG to MagNet?

I have also worked with designers that have their own models, but these were based on their past experience working with hybrid steppers. (And they were typically pretty secretive on the details of how they worked.) Plus the model's accuracy was limited to new models fairly similar to what they had previously worked with.

With respect to the FEA comparison, there isn't a simple answer to that. I am working with JMAG, so I am biased toward that package. Comparing Infolytica to JMAG you will most likely find similar results for basic metrics such as torque, emf and solver time. The differences come in when you want to move beyond the basic analyses or when you want to integrate the EM FEA package with the rest of your analysis tools. Each package has its own strengths, so it is a matter of finding one whose strengths match your needs.

Lin Engineering specializes in custom windings for hybrid stepper motors. Check out Designer's Corner - lots of information on how to maximize torque at speed with custom windings. They don't publish how to build it, but you can see what can be done.