In this post I will talk about Stacked PCB Axial Flux Motors. Stacked PCB (Printed Circuit Board) axial flux motors represent a cutting-edge approach to electric motor design. By replacing traditional copper windings with flat PCB traces, they achieve ultra-thin, lightweight, and highly efficient motors. This technology is gaining popularity in precision robotics, drones, and compact electric vehicles. How Stacked PCB Axial Flux Motors Work: PCB as the Stator: Instead of traditional copper coils wound around an iron core, the stator is made up of multiple layers of PCB, with copper traces forming the motor windings. Flat, planar coils replace bulky wire windings. No iron core, eliminating core losses and cogging torque. Compact and easy to manufacture, as the PCB layers can be precisely fabricated. Permanent Magnet Rotor: The rotor consists of high-strength neodymium magnets arranged in a Halbach array or a standard axial flux configuration. Magnets can be placed on both sides of the stator (Dual Rotor, Single Stator configuration) for higher efficiency. Lightweight materials like plastic, carbon fiber or aluminum can be used to reduce mass. Advantages of Stacked PCB Axial Flux Motors. Ultra-Thin & Lightweight: PCB-based stators are much thinner than traditional copper windings, allowing for extremely compact designs. The lack of an iron core reduces weight dramatically. High Efficiency & Power Density: Lower copper losses due to optimized PCB trace geometry. No iron losses (hysteresis & eddy currents) since there’s no iron core. Higher frequency operation with less heat generation, leading to better performance. Scalability & Automated Manufacturing: PCBs can be precisely manufactured using standard fabrication processes. Multi-layer PCB designs allow for stacking, increasing power output while keeping a thin profile. Easier mass production compared to hand-wound coils. Smooth Operation (No Cogging Torque): Traditional motors with an iron core experience cogging torque, where the rotor "snaps" to preferred positions due to magnetic attraction. PCB axial flux motors have no iron core, so they run silky smooth, which is critical for precision applications like drones, gimbals, and medical robots. Challenges of Stacked PCB Axial Flux Motors. Lower Current-Carrying Capacity: PCB traces have higher resistance than thick copper windings, so current capacity is limited. The solution is to use multiple stacked PCB layers or integrate thicker copper plating for improved performance. Requires Strong Magnets: Since PCB traces are thinner than traditional wire windings, they generate a weaker magnetic field. The solution is to use high-performance neodymium magnets and optimize coil layout. Heat Dissipation: PCB traces have limited thermal conductivity, so heat management can be an issue. The solution is to use thermal vias, heatsinks, or forced air cooling. Stacking PCBs for More Power. To increase performance, multiple PCB layers can be stacked together. >Single-Layer PCB Motor: Very thin and lightweight, but limited power output. Good for micro-robots, precision actuators, and small drones. >Dual-Layer PCB Motor: Two PCB layers increase copper area, improving current capacity. Ideal for higher torque applications like robotic arms. >Multi-Layer PCB Motor (3+ layers stacked): More layers = higher power density without increasing the motor’s footprint. Used in compact high-performance motors for electric bikes, vehicles, and robotics.

Hello, Axial. Welcome! This is a thread that's been long-overdue here on /robowaifu/ . Thanks and looking forward to some great innovations for home-spun actuation motors! Cheers, and have fun! :^) >=== -minor edit

Let's go back to the ending of the first post where we found that DRSS Coreless Axial Flux Motors are ideal for DIY Motors. Design Considerations and Formulas for a Dual Rotor, Single Stator (DRSS) Coreless Axial Flux Motor >A Dual-Rotor Single-Stator (DRSS) Coreless Axial Flux Motor offers high efficiency, low weight, and reduced cogging torque due to the absence of an iron core. These characteristics make it ideal for applications requiring smooth operation, high torque-to-weight ratios, and compact designs. Rotor Design Considerations >Dual-Rotor Configuration: Two rotating discs sandwich a stator, which allows for better magnetic flux utilization and a more balanced force distribution. >Magnet Placement: Typically, Halbach arrays or evenly spaced neodymium magnets (NdFeB) improve flux concentration and reduce leakage. >Magnet Shape: Arc-segmented or trapezoidal magnets improve flux distribution. >Magnetic Strength and Type: There are different grades and formulations of magnets. Neodymium values range from N28 up to N55 with a theoretical maximum at N64. >Air Gap: Must be kept minimal to maximize efficiency while maintaining manufacturability and mechanical stability. Stator Design >Coreless Winding: Since there's no iron core, the windings are self-supporting and encapsulated with epoxy or composite materials. >Litz Wire: Used to mitigate eddy current losses, especially at high frequencies. >Back Iron Plate: A thin back iron plate behind the magnets can improve magnetic circuit efficiency while reducing unwanted stray fields. Electromagnetic Considerations >Magnetic Flux Density (B-field): Needs to be optimized for high torque while avoiding saturation in surrounding materials. >Winding Topology: Can be toroidal (wires wrapping around) or pancake-style (flat windings), impacting performance and cooling. >Eddy Current Losses: Reduced due to coreless design, but conductor heating still needs to be managed. Mechanical Considerations >Structural Rigidity: Since there’s no iron core, the stator must be mechanically reinforced to prevent deformation under electromagnetic forces. >Cooling: Coreless designs rely on forced air, liquid cooling, or heat sinks since there's no core to conduct heat away. >Rotor Balancing: Essential to prevent vibrations at high speeds. Efficiency Considerations >Minimized Joule Losses: The dominant losses are resistive (I^2*R losses) in the windings. >Hysteresis & Cogging Torque: Since there's no iron, these are practically eliminated. >Optimal Speed Range: Coreless axial flux motors tend to be optimized for specific RPM ranges, with efficiency dropping at extremely high or low speeds. Key Mathematical Formulas >Magnetic Flux Density (B-field) >Torque Calculation (Lorentz force law or based on the flux linkage) >Power Output >Back EMF >Electrical Frequency >Eddy Current Losses See picture for formulas. I'm not sure how to post mathematical formulas on here. (I had to delete the post because i chopped one of the formulas off) >>36275 Soon, I hope to post some cool stuff like an Axial Flux Motor Calculator and Model Generator in OpenSCAD. They both need some work before posting. But I'll continue to work on them as much as I can. I have the broad strokes already down and working just a bit of refinement is needed. My goal is anyone can enter some design constraints and have a python program search for motor configurations, output graphs and parameters that the OpenSCAD model generator can use to generate real 3d printable models. I included a sneak peek into the analyzer and models. (Yes that OpenSCAD file was generated from the Motor Configuration Analysis!) I'm sure many of you can spot the issues. All in due time!

>>36277 >My goal is anyone can enter some design constraints and have a python program search for motor configurations, output graphs and parameters that the OpenSCAD model generator can use to generate real 3d printable models. That sounds remarkable, Anon. Godspeed! <---> BTW, these are excellent effort-posts so far, Axial. Really pro-tier. Thanks! Cheers, Anon. :^)

In this post I will focus on motor windings (Delta, Star, and Star-Delta.) and 3 Phase. In a coreless axial flux motor, the winding configuration significantly affects the motor's performance, including efficiency, torque, power output, and control complexity. The three primary winding configurations are Delta (Δ), Star (Y), and Star-Delta (Y-Δ). Each winding configuration offers different electrical and performance characteristics. The Delta (Δ) connection is best for high-power applications, the Star (Y) connection is efficient for lower power with a neutral reference, and the Star-Delta (Y-Δ) transition allows smooth startup with minimal inrush current before switching to full power. For all three configurations below, A1 and A2 are the ends of the A wire. B1 and B2 are the ends of the B wire. C1 and C2 are the ends of the C wire. >Delta In a Delta (Δ) winding, the three-phase windings form a closed loop, with each phase connected end-to-end in a triangle. This provides a lower voltage per phase but allows for higher current handling. Each coil shares its terminals with two other coils, forming a closed loop. Delta connection forms a closed-loop triangle, where each phase winding is connected end-to-end without a neutral. Each phase shares current between two windings, reducing the effective winding resistance. Higher efficiency at higher speeds, suitable for high RPM applications. No neutral point, meaning only three-wire operation. >Delta Connection Mapping (A2 -> B1), (B2 -> C1), (C2 -> A1), The PCB connections are taken from A1, B1, and C1. >(Connect the end of phase A (A2) to the start of phase B) >(Connect the end of phase B (B2) to the start of phase C) >(Connect the end of phase C (C2) to the start of phase A) >Star In a Star (Y) winding, one end of all three windings is connected to a common neutral point. This configuration provides a higher phase voltage and is typically used for lower current applications. The neutral point is where all three windings converge. The Star (Y) configuration has one common neutral point where the ends of all windings meet. This allows for higher phase voltage but limits the maximum phase current. >Star Connection Mapping (A2 -> Neutral), (B2 -> Neutral), (C2 -> Neutral), The PCB connections are taken from A1, B1, and C1. Neutral is connected together on the PCB as Ground or on the Driver as Neutral. >(Connect the end of phase A (A2) to Neutral >(Connect the end of phase B (B2) to Neutral >(Connect the end of phase C (C2) to Neutral In a Star-Delta (Y-Δ) winding it's a hybrid configuration where the motor starts in Star (Y) mode for high torque during startup and then transitions to Delta (Δ) mode for high-speed operation. This configuration switches from Star to Delta using an external relay or electronic switch. After a short duration or when reaching a certain RPM, the system switches from Star to Delta mode. If your robowaifu motor needs torque at low speeds, use Star (Y). If your motor will operate mostly at high speed, use Delta (Δ). If you need both torque and high speed, implement a Star-Delta switch (Y-Δ). A Star-Delta will require more thought, consideration, and electronics. Now I will focus on 3-Phase power. A 3-phase system consists of three alternating currents (AC) that are phase-shifted by 120 degrees from each other. This ensures continuous power delivery, smoother torque output, and efficient motor operation compared to single-phase systems. Three windings (A, B, C) each receive their own AC phase. Each phase alternates between positive and negative voltages, ensuring smooth torque production without dead spots. The sum of the three phases at any point in time is zero, ensuring constant power delivery. Delta (Δ) Winding in 3-Phase: Each phase shares current with two windings at any time. No neutral is needed. The voltage applied across any winding is line-to-line voltage. Creates a looped path for the current, ensuring continuous power. Current Path Example in Δ: >When A is at peak voltage: Current flows from A to B and A to C. The return current is shared through B and C. >When B is at peak voltage: Current flows from B to A and B to C. The return current is shared through A and C. >When C is at peak voltage: Current flows from C to A and C to B. The return current is shared through A and B. Thus, each winding always has some current, producing smooth rotation. Star (Y) Winding in 3-Phase: The three phases meet at a neutral point. Each winding gets line-to-neutral voltage (lower than Delta). The neutral can be grounded or floating. Current Path Example in Y: >When A is at peak voltage: Current flows from A to Neutral. The return current comes from Neutral through B and C. >When B is at peak voltage: Current flows from B to Neutral. The return current comes from Neutral through A and C. >When C is at peak voltage: Current flows from C to Neutral. The return current comes from Neutral through A and B. This configuration is commonly used for high torque at startup, but requires a neutral return path. Star-Delta (Y-Δ) Transition in 3-Phase: The motor starts in Star (Y) mode for high torque. After reaching speed, it switches to Delta (Δ) for higher efficiency. The switching occurs via a relay or electronic circuit. How Star-Delta Switching Works: >Startup (Star Mode): Current flows through a full winding per phase. Higher line-to-neutral voltage. Lower starting current (prevents excessive inrush current). >After Switching to Delta Mode: Current flows through two windings per phase. Higher current capacity. Higher running efficiency. This transition prevents high current draw at startup, while allowing full performance at high speeds.

Magnets are at the heart of any electric motor, and their arrangement can significantly impact performance, efficiency, and power density. One of the most effective ways to enhance motor efficiency is by optimizing magnetic flux using Halbach Arrays. This post will explore magnet types, their properties, and how Halbach arrays can be leveraged to maximize performance in Coreless Axial Flux Motors. Electric motors rely on permanent magnets to generate a magnetic field that interacts with windings, producing motion. The choice of magnet type and configuration influences the motor’s torque, efficiency, and power output. Magnetic flux is a measure of the total magnetic field passing through a given surface. In an axial flux motor, the goal is to maximize flux density while minimizing losses. There are four main types of magnets used in motors, (NdFeB, SmCo, Ferrite, Alnico). >Neodymium Iron Boron (NdFeB): The strongest permanent magnet available. High energy density, making it ideal for high-performance applications. Grades range from N35 to N55, with N55 having the highest magnetic strength. Susceptible to high temperatures; requires coating to prevent corrosion. >Samarium Cobalt (SmCo): Second-strongest permanent magnet. More temperature resistant than neodymium (up to 350°C). More expensive but better suited for harsh environments. Less prone to corrosion compared to NdFeB. >Ferrite (Ceramic) Magnets: Weak compared to NdFeB and SmCo. Cheap and widely available. Suitable for low-cost applications where high strength isn’t required. >Alnico (Aluminum-Nickel-Cobalt): High-temperature stability. Not as strong as NdFeB but used in applications needing high thermal endurance. Key Magnetic Properties: >Remanence (Br) - The residual magnetic strength when the external field is removed. >Coercivity (Hc) - Resistance to demagnetization. >Maximum Energy Product (BH_max) - Indicates how much magnetic energy a magnet can store. >Curie Temperature - The temperature at which the magnet loses its magnetic properties. For coreless axial flux motors, Neodymium (NdFeB) magnets are ideal due to high remanence, strong coercivity, and compact size. Magnetic Flux Paths In an axial flux motor: >Flux travels axially (parallel to the axis of rotation). >It should be concentrated between the rotor and stator for maximum torque generation. >Poor magnet arrangements lead to flux leakage, reducing efficiency. Flux Leakage and Cogging Torque: >Flux leakage occurs when the magnetic field escapes outside the useful path, reducing efficiency. >Cogging torque is caused by magnetic attraction between rotor magnets and stator windings, leading to unwanted jerking in rotation. Both issues described above can be mitigated using Halbach arrays. What is a Halbach Array? A Halbach array is a special arrangement of magnets that enhances magnetic flux on one side while cancelling it on the other. This effect concentrates the magnetic field where it is needed (toward the stator windings), increasing efficiency. How do Halbach Arrays work? In a traditional magnetic setup, flux is evenly distributed on both sides of a magnet. In contrast, a Halbach array manipulates magnet orientation to push all the flux to one side. >Standard Arrangement: Magnetic flux is symmetric, meaning half the energy is wasted. >Halbach Arrangement: Magnetic flux is focused on one side, eliminating the need for a back iron return path. Magnet Orientation in a Traditional Halbach Array: This pattern creates a strong magnetic field on one side while reducing it on the opposite side. You can use cube magnets if you go down this route as their polarities can be easily changed by rotating or flipping the cube. >1st Magnet UP (North-South), 2nd Magnet RIGHT (Sideways), 3rd Magnet DOWN (South-North), 4th Magnet LEFT (Sideways), so on and so forth. Magnet Orientation in a DIY scenario: Traditional Halbach Arrays require specialty magnets with their polarities differing from off the self magnets. Alternating North and South is the go-to method for DIY motors. Less efficient than a true Halbach array but much easier to build. >1st Magnet UP (North-South), 2nd Magnet DOWN (South-North), 3rd Magnet UP (North-South), 4th Magnet DOWN (South-North), so on and so forth. Types of Halbach Arrays >Linear Halbach Array: Used in linear motors and maglev systems. Magnets are arranged in a straight line. >Cylindrical Halbach Array: Used in radial flux motors. Forms a ring of magnets, focusing the field inward or outward. >Disc-Shaped Halbach Array (Axial Flux): Perfect for axial flux motors. Arranges magnets in a circular pattern, maximizing axial flux concentration.

>>36277 >>36277 >Axial Flux Motor Calculator and Model Generator in OpenSCAD That would be fantastic. A wish...could it analyze any shaped motor???

Maybe we should consider a more unconventional design thats more similar to how muscles work

>>36403 By "any shaped", what might you mean? But yeah my goal is you enter as few parameters as possible, like overall motor diameter, motor thickness, required torque, available supply voltage, target RPM and the program would find the best voltage, coil turns, pole/coil configuration, and magnet setup to achieve the desired coreless axial flux motor performance. Then the generator would take all those variables and use them to generate a 3d model. The source for the calculator/finder and generator would all be open for anyone and anyone could extend/modify it to do what you wanted. I could also be bullied to add other/extra features if enough people wanted me to. My current motor calculator/finder/generator actually takes too much time at the moment finding motors, because it takes into account pretty much everything as physically and electrical possible and uses some assumed 3d dimensions of various parts like the 3d printed coil core. Which makes it difficult to find a motor in specific dimensions with specific parameters applied. It also requires too many user entered parameters, at 24 needed. It's highly "by the book" and far too advanced for general use. You really need to know too much about motors for it to be useful because if you knew what you needed to use it, you could just design a motor from scratch any how. Right now I'm rewriting it from scratch to do a multi-stage loop-able calculation where it would >First: Calculate the broad strokes of a motor based on limited desired parameters. >Second: Calculate various possible 3D dimensions >Third: Calculate Nail down possible modifications/compromises based on 3D space requirements of parts and parameters. >Fourth: Analyze everything to verify it would work if generated and made irl, if not loop back modifying certain parameters and try again. >Fifth: Finally, generate 3D models. It's using brute force with heuristics to search atm, in the future gradient descent would be a possibility to refine configurations instead. I'm not applying any constraints upfront to prune the search space (discarding physically infeasible configurations early), i'm just letting the loop-back analysis handle it after broad calculations. I'm just generating everything dynamically based on the given and computed parameters but also planning on including template files for different motor styles, could even include user templates, but this will have to come far later after it's working. It's a command line one-shot input and generate approach, but tweaking and re-run calculations dynamically via an HTML5 webpage is desirable as the graphs are already being generated and displayed in HTML5. The HTML5 UI would need a tiered update system with rough estimates updating instantly, while full calculations run in the background when parameters settle and employing optimization strategies like caching previously computed configurations. >>36430 >Maybe we should consider a more unconventional design thats more similar to how muscles work I've been tinkering with magnetic linear actuators that don't use motors but work kind of like a maglev train. I'll post in the other thread about this soon.

>>36431 >I'll post in the other thread about this soon. >>36432