Description:FIELD OF INVENTION
The invention relates to energy-efficient electric drives, specifically the design and implementation of switched reluctance motors for improving performance and reducing power consumption in industrial exhaust fans.
BACKGROUND OF INVENTION
Switched Reluctance Motors (SRMs) have emerged as a promising solution for improving energy efficiency in industrial applications due to their simple construction, ruggedness, and high torque-to-inertia ratio. Traditional induction motors used in industrial exhaust fans often suffer from efficiency losses under variable load conditions. In contrast, SRMs operate effectively over a wide speed range with minimal energy loss, making them ideal for ventilation systems where speed regulation is crucial. The absence of permanent magnets and rotor windings also makes SRMs more cost-effective and reliable in harsh industrial environments. With the growing demand for sustainable energy solutions and reduced operational costs, industries are increasingly adopting energy-efficient motors. This invention focuses on the design and implementation of an SRM specifically tailored for industrial exhaust fans, aiming to enhance airflow control while minimizing energy consumption. The integration of intelligent control algorithms further contributes to dynamic performance optimization and energy savings in real-time operation.
The patent application number 202341043522 discloses a method and structural arrangement to manufacture a switched reluctance motor for propelling a vehicle. A method and structural design to manufacture a switched reluctance motor that efficiently propels vehicles by optimizing torque, minimizing losses, and enhancing overall energy efficiency.
The patent application number 202231074542 discloses a system employing mixed-signal platform for parameter and position estimation of a switched reluctance motor. The system uses a mixed-signal platform combining analog and digital circuits to accurately estimate rotor position and key parameters in a switched reluctance motor (srm).
The patent application number 202111058042 discloses a mechanical position/speed sensorless multiport switched reluctance motor drive for a solar irrigation pump. A sensorless multiport srm drive uses solar energy to power irrigation pumps efficiently, eliminating mechanical sensors for position/speed, reducing cost and improving reliability.
SUMMARY
The invention focuses on the design and implementation of a switched reluctance motor (SRM) aimed at optimizing energy efficiency in industrial exhaust fans. Traditional induction motors used in exhaust systems are often inefficient under variable load conditions. This project introduces a cost-effective and energy-efficient alternative using an SRM, known for its simple construction, robustness, and high efficiency. The design includes the development of a suitable motor controller and drive circuit to manage the switching sequence of the stator poles for optimal torque generation. By integrating advanced control algorithms, the system achieves precise speed regulation, lower energy consumption, and improved thermal performance. The SRM's ability to operate efficiently across a wide range of speeds makes it ideal for industrial ventilation systems where demand fluctuates. The successful implementation demonstrates substantial energy savings, reduced maintenance, and a lower carbon footprint, making it a viable solution for sustainable industrial operations.
DETAILED DESCRIPTION OF INVENTION
With the rapid advancement of electric vehicle technology, Switched Reluctance Motors (SRMs) have gained significant traction due to their outstanding performance characteristics. However, one of the key challenges limiting their broader application in electric vehicles is the issue of excessive torque pulsation. Addressing this issue is critical for ensuring smoother operation and broader adoption of SRMs in electric drive systems.
Impact of Structural Parameters on Torque Pulsation
The motor’s structural parameters play a vital role in influencing torque ripple. Carefully optimized structural parameters can significantly reduce torque fluctuations, improving overall motor performance and efficiency.
Magnetic Design Considerations
A well-balanced selection of air-gap magnetic flux density is essential—not only for minimizing noise but also for maintaining a stable and efficient operation of the drive motor. Proper magnetic design contributes to enhanced motor performance and acoustic behavior.
Objective of the Work
This paper focuses on mitigating torque pulsation in SRMs through structural parameter optimization. The goal is to improve motor performance by refining critical design elements that influence torque characteristics.
Basic Design Specifications of the SRM
The key design requirements for the SRM used in this electric drive system are summarized below:
Parameter Value
Rated Power 7.5 kW
Rated Voltage 280 V
Rated Speed 1500 r/min
Efficiency 88%
Speed Range 200 – 2000 r/min

Design of Structural Parameters
Design Principles for Structural Parameters
In the structural design of Switched Reluctance Motors (SRMs), key dimensions such as core length, rotor outer diameter, and stator outer diameter significantly influence both motor performance and manufacturability. A critical factor in the design process is the slenderness ratio (λ), which is defined as:

Where:
• l is the core length
• Dr is the rotor outer diameter
If the slenderness ratio is too large, the motor becomes long and slender. This configuration reduces the length of armature winding ends relative to the total winding, which helps in saving copper. It also reduces interference from the core with the end magnetic field, improving the accuracy of magnetization curve predictions from 2D models. Additionally, such designs have lower rotational inertia, making them favorable for faster starting and speed control.
Conversely, a small slenderness ratio results in a thicker, shorter motor with opposite characteristics. Based on practical experience with medium and large AC motors, the slenderness ratio is typically set between 0.5 and 3.0.
In early electromagnetic design stages, the motor's current waveform at the rated operating point is often assumed to be a square wave. The equivalent square wave current is then used to calculate key motor dimensions. The main sizing equation is:

Where:
• ki is the peak winding current coefficient (typically 0.48–0.51)
• km is the square wave current coefficient (typically 0.62–0.81)
• lδ is the effective armature length (generally taken as lδ=1.05ll_\delta = 1.05llδ=1.05l)
• Pem is the electromagnetic power, calculated as:

The ratio between the stator outer diameter and the rotor outer diameter depends on the number of poles and performance requirements, typically ranging between:
Ds : Dr=0.4 to 0.7 (4)
In addition, the stator and rotor pole arc angles must satisfy certain conditions for proper operation. This is usually analyzed using pole arc coefficients (β):

Where:
• βr, βs are the rotor and stator pole arc coefficients
• Nr, Ns are the number of rotor and stator poles
• q is the number of phases
The shaft diameter must ensure mechanical integrity and is typically chosen within:
Di : Dr = 0.4 to 0.5 (6)
Finally, after establishing preliminary structural dimensions, the number of series turns per phase can be estimated using:

Where:
• Nc is the number of coil turns per phase
• U is the voltage
• n is the speed
• B is the magnetic flux density
• θ is the electrical angle
SRM Parameter Determination
The performance of a Switched Reluctance Motor (SRM) is highly dependent on the accurate selection and optimization of its design parameters. Since torque output and efficiency are sensitive to both structural and control parameters, this section outlines a step-by-step method to determine these parameters using simulation tools like MATLAB, RMxprt, and Maxwell 2D.
Parameter Design Workflow
To ensure systematic development of the motor, a parameter design flowchart is created as shown in Figure 1. This flowchart guides the entire process from setting initial specifications to validating the optimized design.

Figure 1. SRM Parameter Design Flowchart
The flowchart includes:
• Input of design specifications (rated power, voltage, speed)
• Preliminary calculations using MATLAB
• Setting up the motor model in RMxprt
• Performance evaluation and efficiency check
• Parametric simulation in Maxwell 2D for torque ripple optimization
MATLAB-Based Parameter Calculation
Using the initial design requirements (refer to Table 1), a MATLAB program is developed to perform the preliminary sizing calculations of the SRM. The program calculates critical parameters such as air gap area, magnetic loading, and dimensions of the stator and rotor.

Figure 2. MATLAB Parameter Calculation Process
After executing the program in the MATLAB command window, key motor parameters are output and stored in the workspace. These serve as inputs for further structural modeling.
2D Modeling in RMxprt
The parameter values obtained from MATLAB are used to build a 2D motor model in the RMxprt module. Key components such as the stator outer diameter, rotor size, coil configuration, and winding layout are defined here.

Figure 3. 2D Model of SRM in RMxprt
Upon simulation in RMxprt, the motor shows an efficiency of 90%, satisfying the design requirement. The model is then exported to the Maxwell 2D simulation tool for advanced analysis.
Parametric Analysis in Maxwell 2D
Once the 2D SRM model is imported into Maxwell 2D, the focus shifts to optimizing torque pulsation, which is a critical issue in SRM performance. Studies show that torque ripple is highly influenced by:
• Rotor outer diameter
• Stator pole arc coefficient
• Rotor pole arc coefficient
These parameters are set as variables for parametric analysis. The default pole arc coefficient is set to 4, and a step size of 1 is used. Multiple simulation runs are conducted to compare torque profiles for each set of parameter values.

Figure 4. 2D Model Setup in Maxwell for Parametric Simulation

Figure 5. Torque vs. Pole Arc Coefficient Comparison Graph
From the simulations, the optimal stator and rotor pole arc coefficients are selected based on minimum torque pulsation while maintaining the desired average torque output.
Final Structural Parameters of SRM
The final structural dimensions of the designed SRM, based on simulation results and optimization, are summarized in Table 2 below:
Table 2. Optimized Structural Parameters of the Designed SRM
Parameter Value Explanation
Stator Outer Diameter (Ds) [mm] 210 Determines the overall motor frame size and magnetic field distribution
Stator Yoke Height (hsy) [mm] 13.8 Ensures magnetic saturation is avoided in the stator core
Stator Pole Arc Coefficient 0.419 Optimized to reduce torque ripple and improve energy efficiency
Rotor Outer Diameter (Dr) [mm] 113 Affects rotor inertia and magnetic interaction with stator
Rotor Yoke Height (hry) [mm] 15.8 Ensures structural strength and magnetic performance of the rotor core
Rotor Pole Arc Coefficient 0.454 Tuned for optimal torque production and reduced pulsation
Shaft Diameter (Di) [mm] 50 Chosen to meet mechanical strength requirements under operating loads
This parameter determination process, supported by MATLAB and electromagnetic simulation tools (RMxprt and Maxwell 2D), enables:
• Accurate initial sizing based on mathematical modeling
• Efficient structure development with real-time simulation
• Optimization of pole arc coefficients to minimize torque ripple
• Achievement of 90% motor efficiency, aligning with performance goals
Simulation Results Analysis
To evaluate the performance improvement after structural optimization, two key metrics are analyzed:
• Average Torque
• Torque Pulsation Coefficient
The average torque is calculated using the following formula:

To quantify torque fluctuation, the torque pulsation coefficient (KT) is defined as:

As shown in Table 3, after optimizing the SRM structure (specifically the stator and rotor pole arc coefficients), the average torque slightly decreases from 19.02 Nm to 18.12 Nm — maintaining over 95% of the original value. However, the torque pulsation coefficient is significantly reduced, reaching 87.11% of its pre-optimization value, indicating improved smoothness and efficiency.
Table 3. Comparison of Average Torque and Torque Pulsation Before and After SRM Optimization
Condition Average Torque (Nm) Torque Pulsation Coefficient
Pre-optimization 19.02 1.63
Post-optimization 18.12 1.42
Conclusion
In this work, a switched reluctance motor (SRM) was designed to meet specific performance targets using a structured approach. Initial parameter estimation was performed through a MATLAB-based program based on the core design principles. These parameters were then used to construct a detailed model in RMxprt, where simulation showed that the SRM achieved an efficiency of 90%, aligning well with the design goals.
Subsequently, the model was imported into Maxwell 2D for advanced simulation and optimization of the stator and rotor pole arc coefficients. The refined model demonstrated improved torque smoothness by significantly reducing the torque pulsation coefficient, with minimal impact on average torque. The results confirm that the optimization process effectively enhances the performance and reliability of the SRM, making it suitable for energy-efficient applications like electric vehicle drive systems.

DETAILED DESCRIPTION OF DIAGRAM
Figure 1. SRM Parameter Design Flowchart
Figure 2. MATLAB Parameter Calculation Process
Figure 3. 2D Model of SRM in RMxprt
Figure 4. 2D Model Setup in Maxwell for Parametric Simulation
Figure 5. Torque vs. Pole Arc Coefficient Comparison Graph , Claims:1. Design and Implementation of a Switched Reluctance Motor for Optimizing Energy Efficiency in Industrial Exhaust Fans claims that the developed Switched Reluctance Motor (SRM) achieves a high energy efficiency of up to 90%, meeting the operational demands of industrial exhaust fans.
2. The SRM was designed using a parameter calculation program in MATLAB based on core motor design principles.
3. Structural parameters were accurately modeled and simulated using RMxprt and Maxwell 2D to validate motor performance.
4. Optimization of the stator and rotor pole arc coefficients led to enhanced torque performance with reduced pulsation.
5. The average torque post-optimization reached 18.12 N·m, maintaining over 95% of the pre-optimization value of 19.02 N·m.
6. The torque pulsation coefficient was significantly reduced from 1.63 to 1.42, representing a 12.89% improvement.
7. The optimization resulted in smoother torque characteristics, improving operational stability and reducing mechanical stress.
8. The motor's compact design and efficient torque delivery make it suitable for energy-critical industrial applications.
9. The SRM demonstrates reliable thermal and magnetic performance under simulated operating conditions.
10. The implementation shows potential for reducing power consumption and enhancing the sustainability of industrial ventilation systems.