Think stack motors are rarely encountered. However, they do exist. BionX, an erstwhile Canadian Company, launched one of the known thin-stack motors in the field of electric bicycles. The large diameter motor with a 12mm stack height had some unusual characteristics. I will discuss that design in a separate post.
Some of the concerns below are about thin stack motors.
Increased Magnetizing Current
A larger air gap increases the reluctance of the magnetic circuit.
This requires a higher magnetizing current to maintain the same flux density, leading to higher copper losses and reduced efficiency.
Reduced Flux Density & Torque Production
The air gap is where the magnetic field transfers between the rotor and stator. A larger gap weakens this field, reducing torque production per ampere.
This forces designers to compensate by increasing current, which raises I²R losses and decreases efficiency.
Increased Leakage Flux
More flux escapes into unintended paths, leading to poor power factor and additional losses.
This can also result in weaker electromagnetic coupling between the stator and the rotor.
Eddy Current Losses in Thin Laminations
Thin stack designs rely on laminations to minimize eddy current losses, but a large air gap increases the fringing effect (flux spreading), which can induce additional losses in the edges of the laminations.
This can cause localized heating and performance degradation over time.
Structural & Mechanical Stability
A large air gap can make the motor mechanically unstable, leading to vibrations and noise.
It also demands tighter machining tolerances to maintain uniformity, increasing manufacturing complexity.
Torque Harmonics
Because of the non-linearities due to saturations in the laminations, the backEMF is no longer sinusoidal, introducing severe harmonics during torque production.
Balancing Stack Height vs. Air Gap
To optimize motor performance while maintaining thin stacks, designers must strike a balance between stack height and air gap:
Increase Stack Height to Compensate for Air Gap Losses
A taller stator stack provides more magnetic material, reducing the reluctance of the core and improving flux linkage.
This helps recover lost torque due to an increased air gap.
Optimize Air Gap Size
A smaller air gap is preferable for efficiency, but practical manufacturing constraints (mechanical tolerances, rotor movement, cooling needs) must be considered.
Using advanced high-permeability materials (e.g., silicon steel laminations) can help minimize the impact of air gap reluctance.
Use High Energy Permanent Magnets (for PM Motors)
In permanent magnet (PM) motors, stronger magnets (e.g., NdFeB) help counteract the effect of a larger air gap by maintaining sufficient flux levels.
Improve Slot and Tooth Geometry
Adjusting stator slot dimensions and tooth shape can help concentrate the flux density, making the motor more efficient even with a moderate air gap.
Consider Air Gap Shape Optimization (or Flux Focus techniques)
A graded or tapered air gap or flux focus technique (instead of uniform spacing) can help direct flux more efficiently, reducing unwanted leakage.
Conclusion
A large air gap in a motor with thin stacks leads to higher losses, lower torque, and efficiency issues. The optimal design requires balancing stack height and air gap size by:
Increasing stack height to compensate for reluctance,
Using high-energy magnetic materials,
Optimizing slot, tooth, and air gap geometries,
Keeping air gap tolerances tight while allowing for mechanical stability.
By carefully designing these factors, motor efficiency can be maximized without excessive material or energy loss.
Due to their efficiency and reliability, Brushless Permanent Magnet (PM) Motors are widely used in high-performance applications. This paper explores analytical methods for modeling and designing such motors. It discusses key aspects like air gap modeling, slot modeling, core loss analysis, and permanent magnet circuit modeling. These analytical techniques help optimize motor performance and improve design efficiency. The study also addresses critical design implications such as air gap corrections, slot width considerations, and the impact of permanent magnets on motor operation.
1. Introduction
Brushless PM motors offer power density, efficiency, and control precision advantages. However, their design complexity requires robust analytical techniques. This paper provides a detailed study of fundamental analytical methods for designing and optimizing these motors. The key focus areas include air gap modeling, slot modeling, and the magnetic circuit representation of PM materials.
1.1 Importance of Analytical Methods in PM Motor Design
Analytical modeling provides insight into the motor’s electromagnetic behavior, reducing reliance on extensive finite element simulations. This enables quick design iteration, leading to more efficient and cost-effective development.
2. Analytical Methods for Brushless PM Motors
2.1 Magnetic Circuit Concepts
The design of brushless PM motors relies on understanding the fundamental properties of magnetic circuits. The governing principles include:
Magnetic flux paths
Permeance variations
Magnetic reluctance calculations
2.2 Air Gap Modeling
Permeance of an Air Gap measures the ease with which a magnetic flux can pass through an air gap in a magnetic circuit. It is the reciprocal of reluctance and is given by:
P=μ0A/g … Equation 1
where:
P = Permeance (measured in Henries, H)
μ0 = Permeability of free space (4π×10−7 H/m)
A = Cross-sectional area of the air gap (m²)
g = Length of the air gap (m)
Since air has a much lower permeability than ferromagnetic materials, the air gap introduces a significant reluctance in the magnetic circuit, which affects the overall magnetic performance of devices like transformers, inductors, and electric motors.
The air gap is critical in defining the motor’s magnetic field distribution. The air gap permeance is determined using the same equation as above:
Pg=μ0A/g … Equation 2
Where Pg is the air gap permeance, μ0 is the permeability of free space, A is the cross-sectional area, and g is the air gap length.
Here are the permeance values for different air gap lengths, assuming a cross-sectional area of 100 mm² (0.0001 m²):
1 mm air gap → 1.26×10−7H
2 mm air gap → 6.28×10−8 H
3 mm air gap → 4.19×10−8 H
As expected, the permeance decreases as the air gap increases, reducing the ease of magnetic flux flow.
What happens in a transformer with an air gap?
Figure 1 – This is an illustration of a transformer core with an air gap highlighting the magnetic flux paths. The laminated iron core is shown in green, with a small air gap in the middle, depicted as a thin separation between the core sections.
In Fig. 1, our primary focus is on the leakage flux around the air gap. If we define a leakage radius of x at the end of the air gap, the permeance for a differential segment dx can be calculated. The effective length of the flux path becomes g + πx, while the additional effective area to consider is L·dx. Pf represents the additional contribution to the total permeance due to the leakage flux.
Let us consider an example:
L = 12 mm g = 2mm A = 50 mm2 Pg = 3.14*10-05 H
If we account for x in the leakage flux, we can use the above equation to determine Pf, representing the additional permeance the leakage flux contributed. The graph at the top (burgundy) shows the percentage contribution, and the graph at the bottom (sky blue) shows the actual value of the contribution. 50% contribution value is achieved at x= 15mm
Effects of Higher Permeance Due to Leakage Flux on Transformer Performance
When higher permeance is caused by leakage flux, it introduces several adverse effects on transformer performance:
Reduced Magnetic Coupling
Leakage flux does not effectively link both primary and secondary windings, leading to weaker electromagnetic coupling.
This results in reduced energy transfer efficiency and increased losses.
Increased Leakage Inductance
Higher leakage permeance leads to increased leakage inductance, which opposes rapid changes in current.
This can cause voltage spikes and transients, affecting the performance of power electronics circuits.
Poor Voltage Regulation
With increased leakage inductance, the output voltage drops significantly under load conditions.
This makes the transformerless effective in applications requiring stable voltage output.
Higher Core Losses & Heating
More leakage flux results in additional eddy current and hysteresis losses, leading to excessive heating.
Increased temperature can reduce the lifespan of the transformer and degrade insulation materials.
Reduced Power Transfer Efficiency
Since leakage flux does not contribute to power transfer, some magnetic energy is wasted.
This decreases the overall efficiency of the transformer.
Potential Electromagnetic Interference (EMI)
Stray magnetic fields from leakage flux can interfere with nearby electronic components.
This is especially problematic in high-frequency transformers used in power electronics.
Key takeaways:
As we move further from the air gap, the contribution of differential permeances decreases.
The exact values chosen are not that critical.
As x increases beyond 10g, the total air gap permeance changes little.
Higher permeance due to leakage flux negatively impacts transformer performance by increasing losses, reducing voltage regulation, and decreasing efficiency.
To mitigate these effects, we need to control and optimize the leakage flux using better winding arrangements, magnetic shielding, or air gaps.
DISCUSSION: Discuss the implications of large air gaps concerning the motor design with thin stacks. How do you balance stack Height vs. air Gap? See the answer here.
Every great innovation starts with an idea—but how do you determine whether that idea can be transformed into an actual, functional product? This is where a feasibility study comes into play. A feasibility study is a structured approach to evaluating whether an idea is viable, focusing on technical know-how, proof of concept, and feasibility demonstration.
1. What is a Feasibility Study?
A feasibility study answers the question: Can this idea be turned into a product? It is the first step in the innovation process, analyzing whether a concept can move from theory to reality.
For example, imagine you have an idea for a car that can achieve 500 miles per gallon. While the concept sounds exciting, the key question is: Is it possible? A feasibility study provides a structured method to evaluate such ambitious ideas.
The study primarily focuses on three critical aspects:
Existing Knowledge and Technology
Demonstration of Concept
Building a Crude Prototype
2. Evaluating Existing Knowledge and Technology
The first step in a feasibility study is assessing whether the existing technology supports your idea. This involves:
Researching journal papers, patents, and technical literature to see if similar concepts have been explored.
Identify previous attempts and understand their successes or limitations.
Determining whether advancements in materials, engineering, or physics make today’s idea feasible.
This theoretical exercise helps establish whether the idea has a scientific or technological basis. If similar work exists, it provides confidence that the idea might be achievable.
3. Demonstrating the Concept
Once research indicates an idea might be possible, the next step is to move beyond theory and prove it through demonstration. This is different from creating a full-fledged product—at this stage, the goal is to show that the technology can work.
A demonstration involves:
Developing a crude prototype—a simplified product version that proves the core technology functions.
Testing whether the concept can produce expected results under controlled conditions.
Focusing on technical feasibility rather than manufacturability or cost-effectiveness.
For instance, in the case of the 500-mpg car, this phase might involve building a small-scale engine prototype that demonstrates the potential for extreme fuel efficiency.
4. Building a Crude Prototype
A crude prototype is an early-stage experimental model designed to verify the feasibility of an idea. It is different from a fully functional prototype because:
It does not need to be cost-effective.
It does not need to be production-ready.
It only needs to prove that the idea works.
This stage is critical because it bridges the gap between theory and reality. If a crude prototype successfully demonstrates the core functionality, the next step would be refining it into a more sophisticated prototype for further testing.
In a Nut Shell
A feasibility study is the foundation of product innovation. It helps innovators determine whether their idea can transition from a concept to a real-world application by:
Assessing existing technology and research.
Demonstrating a working concept through tests.
Building a crude prototype to validate the core technology.
By following these steps, innovators can minimize risk, validate ideas early, and ensure resources are invested in projects with real potential. Whether developing cutting-edge electric vehicles, medical devices, or breakthrough engineering solutions, feasibility studies remain an essential first step in technological advancement.
QUESTION: How would you use the 80/20 principle during your feasibility study? Tell me your answer at Rakesh. Dhawan at Power Electronics Group dot com. or write a comment below.
Also, check out NASA’s nine levels of Technology Readiness, which are very useful for recording a concept’s progress. This is a good framework but not entirely applicable to commercializing a technology that must include first articles, pre-production, and production release activities. Also, in the commercial world, TRL1, 2, and 3 can be combined into a single stage, whereas NASA has to follow a three-stage approach because of the much greater risk and uncertainty of its pursuits of the missions.
NASA’s Technology Readiness Levels (TRLs) provide a systematic framework to assess the maturity of a technology, guiding its progression from conceptualization to operational deployment. This nine-level scale assists in evaluating the development stage of a technology, ensuring it meets the necessary criteria before integration into missions or systems. Below is an overview of each TRL:
TRL 1: Basic Principles Observed and Reported
Description: Initial scientific research begins, focusing on the fundamental principles of the technology.
Example: Observing and reporting basic properties of materials or phenomena.
Description: Practical applications of the basic principles are identified, though they remain speculative without experimental proof.
Example: Formulating potential uses for a newly observed material property.
TRL 3: Analytical and Experimental Critical Function and/or Characteristic Proof-of-Concept
Description: Active research and development commence, including analytical studies and laboratory experiments to validate the feasibility of the technology concept.
Example: Conducting experiments to demonstrate that a new material can function as a semiconductor.
TRL 4: Component and/or Breadboard Validation in Laboratory Environment
Description: Basic technological components are integrated to assess their compatibility and functionality in a controlled environment.
Example: Testing a prototype sensor in a laboratory setting to ensure it operates as intended.
TRL 5: Component and/or Breadboard Validation in Relevant Environment
Description: The technology is tested in an environment that simulates real-world conditions, providing more rigorous validation.
Example: Evaluating the performance of a satellite component in a thermal vacuum chamber that mimics space conditions.
TRL 6: System/Subsystem Model or Prototype Demonstration in a Relevant Environment
Description: A high-fidelity prototype is developed and demonstrated in an environment resembling the operational setting.
Example: Testing a robotic lander in a simulated Martian terrain to assess its performance.
TRL 7: System Prototype Demonstration in an Operational Environment
Description: The prototype is tested in the actual operational environment for which it is intended.
Example: Deploying a prototype Earth-observing instrument on an aircraft to collect atmospheric data.
TRL 8: Actual System Completed and “Flight Qualified” Through Test and Demonstration
Description: The technology has been proven to work in its final form and under expected conditions.
Example: A satellite instrument that has completed all ground testing and is certified for launch.
TRL 9: Actual System “Flight Proven” Through Successful Mission Operations
Description: The technology has been successfully integrated into a mission and has demonstrated reliable performance in an operational setting.
Example: A spacecraft component that has operated successfully during a space mission.
Understanding and utilizing TRLs enables NASA and its partners to manage technological development effectively, ensuring that innovations are sufficiently mature before being incorporated into critical missions.
QUESTION: How should NASA use the 80/20 principle during the nine stages of Technology Readiness Levels? Tell me your answer at Rakesh. Dhawan at Power Electronics Group dot com or write a comment below.
Optimizing five-phase Permanent Magnet Synchronous Motor (PMSM) stator laminationsis essential for achieving high efficiency, low weight, and superior performance. The five-phase configuration provides lower torque ripple, better fault tolerance, and smoother operation than traditional three-phase motors. Key design considerations include minimizing magnetic saturation, reducing flux leakage, and balancing lamination and copper weight. This article outlines the essential rules for optimizing laminations in five-phase PMSM stators to enhance motor efficiency and reliability.
1. Minimize Lamination Weight While Maintaining Magnetic Performance
Reducing the weight of the stator laminations improves the power-to-weight ratio while maintaining magnetic performance.
A. Core Geometry Optimization
Increase Yoke Thickness: Prevents local saturation while keeping iron losses low.
Optimize Tooth Width: Ensures proper flux distribution and prevents over-saturation in the core.
Slot/Tooth Ratio Adjustment: Balancing slot openings and stator teeth improves flux flow efficiency.
B. Material Selection for Low Core Losses
Use high-grade electrical steel (e.g., M350-50A, NO20, or Hiperco 50) for improved magnetic efficiency.
Thinner laminations (≤0.5mm) reduce eddy current losses, improving motor efficiency.
Consider higher permeability materials to handle higher flux densities without saturation.
2. Reduce Copper Weight Without Compromising Performance
Optimizing copper winding design in five-phase PMSMs reduces weight and losses while maintaining efficiency.
A. Improve Slot Utilization
Use trapezoidal or semi-closed slots for higher slot fill factor and reduced excess copper usage.
Opt for Litz wire or rectangular conductors to minimize skin effect losses.
Reduce end winding length to lower resistance and heat dissipation.
B. Optimize Winding Parameters
Adjust turns per phase and wire gauge to balance ampere-turns, efficiency, and weight.
Ensure shorter end windings to minimize copper losses.
3. Magnetic Saturation Considerations in Stator Design
Magnetic saturation occurs when the stator core reaches its flux density limit, leading to excessive core losses and heating.
A. Understanding Magnetic Saturation
Five-phase PMSMs distribute flux more evenly, but excessive saturation still causes losses and efficiency drops.
Most electrical steels (e.g., M350-50A) saturate around 1.8–2.0T.
Excessive flux density increases iron losses, torque ripple, and heat generation.
B. Strategies to Prevent Magnetic Saturation
Increase Yoke Thickness to distribute flux more evenly.
Use High-Permeability Materials to handle higher flux densities.
Adjust Winding MMF to prevent over-excitation and excessive core flux.
Improve Magnetic Circuit Balance by using flux guides or auxiliary slots.
4. Flux Leakage Issues for Smaller Stack Lengths
Flux leakage occurs when magnetic flux does not fully link the stator teeth and rotor magnets, reducing motor efficiency. This issue is more severe in shorter stack lengths due to higher end effects and flux path disruptions.
A. Consequences of Flux Leakage
Reduced Torque Output: Less flux links with the rotor, leading to lower power.
Higher Core Losses: Uncontrolled leakage flux increases eddy current and hysteresis losses.
Lower Power Factor: Leakage reactance negatively impacts efficiency.
Uneven Magnetic Fields: Causes torque ripple and cogging issues.
B. Strategies to Minimize Flux Leakage
Increase Stator Stack Length (if weight permits).
Optimize Air Gap and Magnetic Path for better flux linkage.
Improve Winding Distribution using fractional-slot or concentrated windings.
Modify Rotor Design (e.g., skewed rotors or optimized magnet positioning) to guide flux effectively.
5. Balancing Saturation, Flux Leakage, and Weight
Increasing yoke thickness reduces saturation but adds weight.
Extending stack length improves flux linkage but increases weight and cost.
Optimizing slot and winding geometry enhances efficiency without adding unnecessary material.
Conclusion
By following these rules for five-phase PMSM stator optimization, engineers can enhance motor efficiency, reduce weight, and improve overall performance. The five-phase configuration already provides lower torque ripple and better efficiency. Still, carefully managing magnetic saturation, flux leakage, and material selection is key to designing high-performance motors with superior power-to-weight ratios.
A five-phase permanent magnet (PM) motor is an advanced electric motor configuration that offers superior performance to traditional three-phase motors. These motors are used in applications requiring higher torque density, smoother operation, and greater fault tolerance. Below is a patent for a typical five phase motor with 25-slots and 22-magnets.
1. Advantages of a Five-Phase PM Motor
Higher Torque Density
Five-phase motors reduce torque ripple, providing a smoother power output.
More frequent torque production cycles reduce pulsation.
Improved Fault Tolerance
If one phase fails, the motor can still operate with reduced performance.
This is critical in high-reliability applications like aerospace and defense.
Lower cost due to mass production and availability
Higher cost due to specialized components and design complexity
Application Areas
Industrial drives, electric vehicles, renewable energy
High-reliability applications like aerospace, military, and robotics
Motor Size and Winding Density
Standard size with conventional windings
Requires optimized slot-pole combinations for winding efficiency
Noise and Vibration
More noticeable noise and vibration due to lower phase count
Quieter operation due to smoother torque profile
Key Takeaways
Three-phase motors are cheaper, simpler, and widely available, making them the standard for most industrial applications.
Five-phase motors excel in efficiency, torque smoothness, and fault tolerance, making them ideal for critical applications.
Five-phase motors’ higher cost and inverter complexitylimit their widespread adoption, but they are superior for high-performance applications like aerospace, robotics, and electric mobility.
The principles behind the operation of electric motors are a tremendous gift of nature. Uncovering those principles and focusing on their precise and accurate applications makes for an elegant and beautifully designed electric motor. I love the electric motor design, and today, I wanted to share this beautiful plot of the flux density distribution of a new IPM motor.
IPM Motor with Flux Density Contours
There’s something almost magical about how flux density distributes inside an electric motor, especially when they’re as elegantly engineered as Interior Permanent Magnet (IPM) motors.
If you’ve ever wondered why your electric car zips around so quietly or how industrial machines deliver such reliable power, IPM motors often play a key role. Here’s a quick rundown of why these motors are unique and what you’re seeing in that eye-catching color plot of flux density contours.
What Is an IPM Motor?
“IPM” stands for “Interior Permanent Magnet.” Unlike other motor types where the magnets might be placed on the outer surface of the rotor, IPM motors embed the permanent magnets inside the rotor. This gives them a few advantages:
Enhanced Efficiency: By placing magnets within the rotor, the motor can harness magnetic and something called reluctance torque, helping it deliver higher efficiency under various speeds and loads.
Robust Construction: Tucking magnets inside offers better mechanical protection (applicable at high rotation speeds or in demanding environments).
Improved Performance at High Speeds: IPM motors often excel at delivering torque effectively at higher RPMs—one of the reasons they’re a big deal in electric vehicle applications.
Understanding the Flux Density Contours
The colorful image is a snapshot of the “flux density” distribution. Flux density (measured in Teslas) tells us how concentrated the magnetic field is at each point in the motor. Here’s the gist of the color-coded zones:
Blue Regions: Typically show lower flux density. These areas might be where the field passes through less magnetic material or experiences more air gaps.
Green to Yellow Zones: Indicate higher flux density, meaning the magnetic field is stronger there. These zones often show how the magnetic field routes through the rotor and stator teeth.
Bright or High-Intensity Colors: If you see reds or bright yellows, those areas have powerful magnetic fields—often around the magnets or stator teeth tips.
Why It Matters
It is crucial for engineers to see how the magnetic field flows because it helps optimize the motor’s design. By tweaking magnet placement, rotor geometry, or even the materials used, designers can:
Maximize Torque Output: Ensuring the magnetic circuit is efficient.
Minimize Losses: Reduce heat and ensure you get more power for every watt of electricity going into the motor.
Improve Reliability: Avoiding “hot spots” or regions of mechanical stress that could lead to premature failure.
A Future of Quiet, Efficient Power
IPM motors aren’t just for cars; they pop up in everything from drones to washing machines. Their blend of efficiency, power density, and durability makes them a popular choice in modern motor-driven systems. As battery and power electronics technologies advance, IPM motors will likely become even more integral to everyday life—giving us smoother, quieter, and more energy-efficient ways to move and make things.
The 80/20 principle, also known as the Pareto Principle, suggests that roughly 80% of the effects come from 20% of the causes. When it comes to hardware design, applying the 80/20 principle can help optimize efficiency and focus resources on the most critical aspects. Here are some ways to utilize the 80/20 principle in hardware design:
Identify Critical Features: Determine the key functionalities and features for the hardware design’s success. Focus on the 20% of features that will deliver 80% of the value to the end-users. This allows you to allocate resources effectively and prioritize the essential elements.
Design for Common Use Cases: Analyze the most common use cases and requirements for the hardware. By identifying the 20% of scenarios that cover 80% of user needs, you can streamline the design process and optimize performance for those primary use cases. This approach helps avoid overengineering and unnecessary complexity.
Prioritize Design Constraints: Identify the critical design constraints and factors that significantly impact the hardware’s overall performance, cost, and reliability. Allocate resources and effort to optimizing these key areas, ensuring they meet the required specifications while considering the trade-offs for less critical aspects.
Focus on Robustness and Reliability: Identify the 20% of components, subsystems, or functionalities that are most likely to fail or cause issues. By focusing on improving their robustness, reliability, and quality, you can enhance the overall performance and longevity of the hardware. This targeted approach allows for effective resource allocation and risk mitigation.
Iterative Design and Feedback: Adopt an iterative design process and collect feedback from users, stakeholders, and experts. This enables you to identify the most critical areas for improvement and refine the hardware design iteratively. You can improve substantially by addressing the 20% of user satisfaction issues.
Continuous Improvement: Continuously assess and evaluate the hardware design to identify areas of inefficiency, waste, or redundancy. By applying the 80/20 principle to ongoing improvement efforts, you can focus on the most impactful changes resulting in the most significant overall benefit.
Remember that the 80/20 principle is a guideline and may not always be exact. The specific percentages may vary depending on the project and context. The goal is to identify the vital few factors or aspects that significantly influence the hardware design’s success and allocate resources accordingly.
At PEG, we practice an integrative approach involving Simulation in the complete product development cycle. It is important to understand the role of simulation in every phase of the product development cycle. Below is a summary of how simulation can be used in each stage:
1. Concept Phase:
During this phase, use simulation tools to verify circuit operation. One must start small using ideal component models and build the system in stages. Each stage work should be saved. It is important to understand the theory and state of the art behind the circuit you are about to simulate. Without proper theoretical foundation, you will not be able to obtain useful information from simulation.
Also, for majority of the engineers, a process methodology or steps to design must include simulation. Simulation is most effective when the circuit behavior is not well understood and we can construct several what-if scenarios or use simulation to build a repertoire of questions to be answered about the design problem at hand. Simulation effectiveness improves with experience and time. An engineering department must be dedicated to it. As with any other skill, to yield simulation as a potent competitive weapon, one must spend significant time and resources to hone it. A frivolous relationship or experimental tinkering with simulation tools will not yield any fruitful results.
2. Design Phase:
During design phase, as you begin to transform your work into schematics, one must pay careful attention to component selection and component models can be incorporated (especially in Spice based tools) one at a time.
Do not be too ambitious to incorporate a host of models at one time. Also realize that incorporating each component model is never required. One must be quite prudent in incorporating essential component models. Just remember Pareto’s principle – 20% or less determine 80% or more of the outcome. This must always be kept in mind
3. Prototype Phase:
During this phase as prototypes are built, one must pay careful attention to collecting data during incoming inspection (mechanical variables) and testing (electrical variables). Here, we always recommend to use the suppliers who would also build production units. It is important to do so to understand supplier capabilities and process variations.
4. First Article Phase:
During this phase as First Articles are built, one must pay careful attention to collecting data during incoming inspection (mechanical variables) and testing (electrical variables). During this phase, we use statistics to understand variable distributions and correlation between various parameters. These correlations may change from the prototype stage.
It is important to start forming new hypothesis can tremendously expedite the whole product development cycle. During this phase, at PEG, we strongly recommend using statistics to understand variable distributions and correlation between various variables. It is important to start forming hypothesis on what could be troublesome variables which are going to effect the performance. Those variations must be incorporated into Simulations to re-characterize the system and understand overall performance variations.
5. Pre-Production/Production Phase:
During this phase as Pre- Production or Production units are built, one again must pay careful attention to collecting data during incoming inspection (mechanical variables), in-process inspection (mechanical and electrical variables) and final testing (electrical variables). During this phase, we use statistics to understand variable distributions and correlation between various parameters.
These correlations may change from the earlier phases. It is important to start forming fresh hypothesis on what could be troublesome variables which are going to effect the system performance. Those variations must be incorporated into Simulations to re- characterize the system and understand overall performance variations. This is the process of continuous improvement and PEG’s integrated approach, if followed rigorously, yields not only superior products but also strong infrastructure capabilities.
There is always an “Edison approach” to design. With this approach, you will need to spend countless hours and follow rigorous and scientific method of design of experiments as well as truthful collection of data. “Edison approach” is simply too expensive and unaffordable in today’s world. Nevertheless, with enough money and time, such approach is always possible.
LTSpice and PSpice are great tools for Power Electronic circuits barring their annoying and most irritating convergence problems. These convergence problems are a great waste of time and a source of frustration. However, there has been a steady rise in the tools and techniques in the Spice arena, especially for the Power Electronics and Motor Control areas. Spice and other available tools expertise can be wielded effectively in launching new products through short product development cycles. By no means, we are claiming that Spice expertise in Power Electronics alone is sufficient to cut the time from concept to production. However, it is an important tool to have in the bag.
For Power Electronics Circuits, PEG recommends the following approach to using Spice during the Concept Phase only:
Before you build your own circuit model, search to see if similar circuits are available in the public domain. A great engineer always builds her/his work on what is already available. Do not reinvent the wheel.
Always start with the most ideal circuit model of components. Simplicity is the key. Sub-circuits are great in ensuring that small parts of circuits can be made to work first. It is always prudent to use simple, well-tested models.
Now, transient analysis using ideal components will get you only so far. Small Signal modeling is an important step in being able to overcome convergence problems as well as understand the circuit behavior fully. This technique requires state space averaging and is most vital in simulating Power Electronic circuits. PEG specializes in small signal modeling of the Power Electronic circuits and if you run into hot waters using this technique, we are happy to help.
Control loop compensation is not a simple matter for most of the Power Electronic circuits. However, the compensator can be easily designed using the small signal modeling techniques.
Once the above steps are followed and we have a working simulation, we can begin to run various what-if scenarios to understand the circuit behavior in time domain as well as frequency domain.
