The landscape of electric motors is witnessing a significant transformation with the emergence of switched reluctance motor (SRMs). As a professional manufacturer of motor cores in China, we delve into the potential of SRMs, particularly in the context of electric vehicles (EVs). SRMs are gaining attention due to their unique construction, low manufacturing costs, and promising performance metrics. In this blog, we explore the different types of SRMs, their advantages, design challenges, and their viability in shaping the future of electric mobility.
Types of Reluctance Motors
There are two types of reluctance motors, switched reluctance motors (SRM) and synchronous reluctance motors (SynRM). Switched reluctance motors use concentrated windings, while synchronous reluctance motors use distributed windings.
Synchronous reluctance motors have less torque ripple than switched reluctance motors and therefore operate more quietly. Additionally, synchronous reluctance motors are more efficient than switched reluctance motors. This is because switched reluctance motors require higher phase currents, while synchronous reluctance motors have lower flux density.
Synchronous Reluctance Motor
The stator structure of the synchronous reluctance motor is almost the same as that of the induction motor. The rotor consists of a circular laminated iron core with a stamped magnetic flux barrier layer. The rotor is not suitable for high speeds because for high speeds additional magnetic strips must be inserted into the flux barrier to ensure speed stiffness.
However, these grids have a negative impact on the efficiency of the motor. The torque ripple of a synchronous reluctance motor is much smaller than that of a switched reluctance motor. The efficiency is also much higher than that of switched reluctance motors.
Switched Reluctance Motor
Switched reluctance motor (SRM) is also called SR motor. The stator and rotor of switched reluctance motor are composed of salient poles. The stator has a concentrated winding, which means each tooth carries one winding.
The coil is directly wound on the stator teeth, or it can be wound on the skeleton and then inserted into the stator teeth to obtain a higher coil filling factor. The salient pole rotor does not have magnets and windings.
The number of stator poles and rotor poles must be different. Typically, the number of poles in the stator is greater than the number of poles in the rotor. A typical combination is 6/4, i.e. 6 stator poles and 4 rotor poles. Since the rotor consists of only one lamination, switched reluctance motors are particularly suitable for very high speeds.
The switched reluctance motors are relatively simple to produce because the windings can be pre-wound and simply pushed onto the teeth of the stator. Switched reluctance motors have higher torque ripple, which makes the motor noisier than, for example, a synchronous reluctance motor.
Switched reluctance motors, also known as variable reluctance motors, are gaining traction in industrial applications such as EV and wind energy systems due to their simple and robust construction.
Compared with other types of motors such as induction motors, permanent magnet synchronous motors, and brushless DC motors, switched reluctance motors have higher efficiency, better reliability, higher fault tolerance, higher constant power speed ratio (CPSR), and high temperature resistance.
Advantages of Switched Reluctance Motors
Switched reluctance motors present several advantages over traditional motor types:
Simple and Robust Structure
SRMs boast a sturdy design without the need for magnets or brushes, enhancing reliability and durability.
Higher Efficiency and Reliability
With improved thermal performance and reduced material costs, SRMs offer enhanced efficiency and reliability in various applications.
Lightweight and Low Complexity
The absence of permanent magnets simplifies the construction of SRMs, resulting in lighter-weight solutions with lower complexity.
Design Challenges
Motor design entails overcoming various challenges related to electromagnetic, thermal, and structural analyses.
Finite Element Analysis (FEA) tools facilitate the evaluation of static and dynamic performance characteristics, aiding in the optimization of motor geometries and winding configurations.
Challenges include minimizing torque control, estimating losses, and ensuring adequate cooling during operation.
Conclusion
In conclusion, switched reluctance motors represent a compelling alternative for meeting the growing electrification demands in the automotive industry, particularly in EVs, without relying on permanent magnets.
While both SRMs and SynRMs offer distinct advantages, the choice of motor topology remains contingent on the specific constraints and performance requirements of electric vehicles.
Through continuous advancements in design and control technologies, SRMs are poised to play a pivotal role in shaping the future of electric mobility, offering efficiency, reliability, and cost-effectiveness.
Lamnow – Switched Reluctance Motor Laminations Manufacturer
Lamnow is a leading manufacturer of motor lamination stacks based in China, specializing in producing a wide range of motor lamination cores for various applications.
Our product includes laminations for switched reluctance motors, brushless DC motors, DC motors, linear motors, direct drive motors, induction motors, permanent magnet synchronous motors, and universal motors. These motor laminations find extensive use across industries such as automotive, transportation, industrial automation, household appliances, textile machinery, and renewable energy systems.
At Lamnow, we are committed to delivering high-quality motor laminations that meet the stringent performance and efficiency requirements of our customers.
FAQS
How does a Switched Reluctance Motor differ from other motor types?
Unlike traditional motor types such as induction motors or permanent magnet motors, SRMs do not rely on permanent magnets or field windings for excitation. Instead, they utilize the variation in magnetic reluctance to produce torque.
Is the switched reluctance motor AC motor or DC motor?
The switched reluctance motor (SRM) is typically categorized as an AC motor. Although it operates using direct current (DC) power for its control electronics, the motor itself functions on the principles of alternating current (AC). SRMs rely on the sequential energization and de-energization of stator windings to generate motion, making them inherently an AC motor type.
What are the main applications of Switched Reluctance Motors?
SRMs find applications in various industries, including automotive, industrial automation, aerospace, renewable energy, and household appliances. They are particularly well-suited for applications requiring high torque density and reliability.
