Permanent Magnet Synchronous Motors (PMSMs) are highly favored for their excellent efficiency and power density, which is largely attributed to the permanent magnets used on their rotors.
The use of permanent magnets eliminates the need for exciting current, thus significantly reducing electrical losses.
However, achieving the highest efficiency in PMSM design is no easy task.
This complex process requires precise control of various types of energy losses to minimize them.
Key Influencing Factors in the Design of High – Efficiency Permanent Magnet Motors
Designing high – efficiency permanent magnet motors requires comprehensive consideration of several interrelated factors, all with the core aim of reducing electrical, magnetic, and mechanical losses.
Permanent Magnet Characteristics and Placement
The fundamental advantage of permanent magnet motors in terms of efficiency stems from their permanent magnets.
1.Magnet Material Characteristics
The choice of permanent magnet materials is of great significance. Materials such as neodymium – iron – boron (NdFeB) or samarium – cobalt (SmCo) significantly affect the magnetic field strength and demagnetization resistance.
Magnets with high energy density can generate a stronger magnetic field, which can output higher torque at a given current, directly improving the motor efficiency.
When choosing, purchasers must select reliable suppliers who can not only provide high – quality and certified magnet materials but also recommend the most suitable magnet types and solutions based on specific application requirements.
2.Magnet Size and Volume
Optimizing the size and volume of the magnets is of utmost importance.
Generally, larger magnets tend to provide a more powerful magnetic field.
However, this not only increases costs but also, if the magnets are not properly segmented or laminated, leads to higher eddy – current losses inside the magnets.
Therefore, in the design process, it is necessary to find a delicate balance among pursuing a strong magnetic field, controlling costs, and reducing eddy – current losses to optimize the overall performance and efficiency of the permanent magnet motor.
Magnet Placement (Rotor Topology)
1.Surface – Mouentd Permanent Magnet Synchronous Motor (SPMSM)
In this type of motor, the magnets are mounted on the rotor surface, resulting in a relatively simple design.
Nevertheless, in high – speed applications, centrifugal force can limit its performance, and the reluctance torque it can provide is relatively small.
This is because when the magnets are placed on the rotor surface, the effect of centrifugal force is significant during high – speed rotation, which may affect the stability of the magnets and the performance of the motor.
2.Interior Permanent Magnet Synchronous Motor (IPMSM)
In this type of motor, the magnets are embedded inside the rotor.
This design offers better mechanical stability during high – speed operation.
Thanks to the saliency effect (i.e., the difference in inductance between the d – axis and q – axis), it can generate additional reluctance torque.
Especially in the field – weakening region, this reluctance torque can significantly increase the overall torque and efficiency.
For example, in some scenarios where the motor needs to operate at high speeds and requires high torque, this characteristic of the IPMSM gives it a distinct advantage.
Magnet Segmentation
Dividing the permanent magnets into smaller pieces helps to reduce the eddy – current losses inside the magnets.
When the motor is running at high speed, the magnetic field changes rapidly, and this method of magnet segmentation becomes particularly crucial at this time.
Because smaller magnet blocks can limit the formation range of eddy currents, reducing the energy losses caused by eddy currents, thus improving the efficiency of the motor during high – speed operation and ensuring that the motor can maintain good performance under complex working conditions.
For customers with in – depth technical and customization requirements, some professional manufacturers can provide more refined magnet segmentation and assembly techniques.
Stator and Rotor Core Design
Magnetic circuit components play a key role in minimizing core losses.
Electrical Steel (Laminations)
1.High – Quality Silicon Steel
Using thin, low – loss high – grade silicon steel laminations is extremely important for reducing hysteresis losses (energy lost during the magnetization and demagnetization of the core) and eddy – current losses (circular currents induced in the core material).
The thinner the laminations and the higher the silicon content, the higher the motor efficiency.
2.Lamination Factor
A higher lamination factor can ensure a tight core, minimize the air gap, and thus improve the quality of the magnetic circuit.
Stator Slot Geometry
1.Slot Shape and Dimensions
The design of the stator slots, including factors such as slot opening width, slot depth, and tooth width, affects the magnetic field distribution, cogging torque, and torque ripple.
An optimized slot design can minimize these adverse effects, achieve smoother operation, increase the effective torque, and thus improve the motor efficiency.
2.Slot Fill Factor
Maximizing the slot fill factor (i.e., the proportion of the slot area occupied by the wire) allows for more copper wires to be installed, which can directly reduce copper losses
Rotor Structure and Magnetic Barriers
For Interior Permanent Magnet Synchronous Motors (IPMSM), the magnetic barriers (non – magnetic regions in the rotor) designed around the magnets play a crucial role in maximizing the reluctance torque and shaping the magnetic field to minimize harmonic losses.
This usually requires in – depth technology and customization, relying on experienced engineers for fine – tuned magnetic circuit optimization and simulation.
Winding Design
Electrical windings are the main factor contributing to copper losses.
Winding Types
In the winding design of permanent magnet motors, there are two options for winding types: distributed windings and concentrated windings.
Distributed windings can make the magnetic field distribution uniform and have low harmonics; concentrated windings are simple to manufacture and have short end – windings.
Distributed windings can enhance the stability and reliability of motor operation with their uniform magnetic field distribution and low harmonics.
Concentrated windings can reduce production difficulty and costs due to their simple manufacturing process, and the short end – windings help to reduce copper losses and improve motor efficiency.
These characteristics of winding types bring significant value.
If manufacturers focus on the stability and reliability of motor operation, distributed windings can reduce motor failures caused by uneven magnetic fields and harmonics, lower after – sales maintenance costs, and enhance product reputation.
If they pursue efficient production and low costs, the simple manufacturing process of concentrated windings can speed up production and reduce manufacturing costs.
At the same time, reducing copper losses can improve motor efficiency, helping users save energy consumption costs, whether in industrial production or daily use, and actually creating more economic value for users.
Wire Cross – sectional Area
In the winding design of permanent magnet motors, copper wires with a larger cross – sectional area are used as conductors.
This feature can directly reduce the winding resistance and significantly decrease the copper losses generated by the current passing through the winding resistance, making the current transmission smoother and reducing the useless energy losses on the resistance.
The low copper losses resulting from using wires with a larger cross – sectional area mean a reduction in motor energy consumption.
Over the long – term operation, it can save you a large amount of electricity bills.
Moreover, smooth current transmission can effectively reduce motor heating, extend the service life of various motor components, and reduce the maintenance and replacement costs of the motor, providing you with more stable and economical power support for your production or life.
Number of Turns and Phases
The number of turns and phases of a permanent magnet motor are two key parameters that can have an important impact on the motor’s back – electromotive force, current level, and overall voltage/current characteristics, and they need to be matched with the drive electronics.
By reasonably setting the number of turns and phases and precisely matching them with the drive electronics, the motor’s back – electromotive force, current level can be effectively adjusted, and the voltage/current characteristics can be optimized, ensuring that the motor can achieve efficient conversion between electrical energy and mechanical energy under any working conditions.
Proper settings of the number of turns and phases can enable the motor to maintain the best operating efficiency under different working conditions.
This not only reduces energy consumption and saves you electricity costs but also reduces motor wear and the failure rate, extends the motor’s service life, and reduces equipment maintenance and replacement costs, comprehensively enhancing your user experience and economic benefits.
Winding Connection (Star/Delta)
Motor windings have two connection methods, namely star and delta.
These two connection methods will affect the current and voltage levels during motor operation.
Selecting the appropriate connection method according to different working scenarios can specifically regulate the current and voltage levels, thereby effectively reducing the energy losses during motor operation, optimizing the motor performance, and significantly improving the efficiency and stability of motor operation.
Correctly choosing the winding connection method can enable the motor to perform at its best in a specific working scenario.
Reducing energy losses means reducing electricity costs, which can save you a considerable amount of money over the long – term.
At the same time, optimized performance and higher operating stability can reduce the frequency of motor failures, extend the motor’s service life, and reduce maintenance and replacement costs, providing you with reliable and economical power support for your production, operation, or daily life.
Thermal Management
Heat, as a direct product of energy losses, is highly likely to have a negative impact on the efficiency and service life
Efficient Cooling Systems
The ability to effectively dissipate the heat generated by copper losses, core losses, and mechanical losses plays a decisive role in the performance of permanent magnet motors. There are various ways to achieve efficient heat dissipation.
For example, a carefully optimized fan design can enhance air flow to take away heat through reasonable blade shapes and speed control.
Or an internal cooling channel can be constructed to allow the cooling medium to circulate inside the motor, efficiently absorb and transfer heat.
For high – power applications, liquid cooling is an even more effective heat – dissipation method.
Maintaining a lower operating temperature can not only improve the conductivity of the windings, reducing energy losses caused by resistance, but also prevent the permanent magnets from demagnetizing due to high temperatures, ensuring the stable and efficient operation of the motor.
For customers pursuing specific performance and application scenarios (such as high – power density, continuous operation, or harsh environments), the efficiency and reliability of the motor cooling system are key evaluation indicators.
High – temperature Insulation Materials
Selecting insulation materials with a higher thermal rating allows permanent magnet motors to operate safely and stably in a relatively high – temperature environment without performance degradation, thus effectively maintaining the motor’s operating efficiency and service life.
This material is like a “protective shield” for the motor. Even at high temperatures, it can reliably isolate the current, ensure the normal operation of various internal components of the motor, and avoid failures such as short – circuits caused by insulation failure, providing a solid guarantee for the long – term stable operation of the motor under complex working conditions.
Motor Control Strategies (Drive Integration)
The efficiency of a permanent magnet motor system depends not only on the motor itself but also on its control method.
Field – Oriented Control (FOC)
Adopting the advanced control strategy of Field – Oriented Control (FOC), it can precisely control the motor’s magnetic field and the current components that generate torque.
It can minimize motor losses and ensure that the motor operates efficiently within a wide range of speed and torque intervals, enabling the motor to fully exert its performance advantages under different working conditions and achieve efficient and stable operation.
The FOC control strategy brings many benefits. Efficient operation means reduced energy consumption.
Over the long – term, it can save you a large amount of electricity bills and reduce operating costs.
And the stable and efficient operation of the motor under different working conditions can effectively reduce production stoppages or equipment failures caused by unstable motor performance, improve production efficiency, extend equipment service life, and comprehensively ensure the smooth progress of your production and operation, creating more value for you.
Maximum Torque per Ampere (MTPA) Control
This strategy focuses on optimizing the motor current angle.
Given a certain stator current, this strategy can enable the motor to output the highest torque.
Especially when the motor is operating at a low speed, it can maximize the efficiency, achieving the generation of a large torque with a small current and effectively reducing unnecessary energy consumption.
In low – speed application scenarios, such as the starting of electric vehicles or the low – speed operation of industrial equipment, the motor can generate a sufficiently large torque with less electricity consumption thanks to this strategy, reducing energy consumption costs.
Moreover, reducing energy consumption helps to extend the equipment’s battery life or continuous working hours, reducing work interruptions caused by frequent charging or energy replenishment, greatly improving the equipment’s use efficiency and convenience, and providing you with more efficient and stable power support for your production and life.
Field – Weakening Control
Permanent magnet motors are equipped with field – weakening control functions.
When the motor needs to operate at a high speed exceeding the base speed, this function can precisely reduce the effective magnetic flux, expanding the motor’s speed operating range.
During the high – speed operation stage, it minimizes the motor’s energy losses, effectively adjusts the magnetic field, and ensures that the motor remains efficient and stable even at high – speed operation, avoiding a significant increase in losses caused by improper magnetic fields.
During high – speed operation, precise field – weakening control greatly reduces unnecessary energy waste and reduces energy consumption costs.
Over the long – term, it can save a large amount of expenses. At the same time, it ensures the stable and efficient operation of the motor at high speeds, reduces the risk of equipment failure, extends the motor’s service life, and improves production efficiency.
Whether it is industrial production equipment or high – speed transportation vehicles, it can bring you a reliable and efficient power experience.
From the perspective of cost and return on investment, investing in an advanced control system that perfectly matches the high – efficiency motor, although it may increase the initial investment, can bring significant long – term energy – efficiency improvements and accelerate the return on investment.
Creating a high – efficiency permanent magnet motor demands meticulous consideration of multiple factors.
Magnetic materials, structural design, thermal management, winding design, and control systems all play pivotal roles.
Companies like JiaYu understand these intricacies well.
R&D team delves deep into each factor, constantly innovating to optimize motor design.
By leveraging advanced magnetic materials and cutting – edge structural designs, they enhance magnetic flux utilization.
Their focus on thermal management ensures stable motor operation under various conditions.