Broad-pole BLDC Motor Torque Ripple Reduction
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Solution Overview
Problem
Conventional square-wave permanent magnet motors suffer from large switching torque fluctuations and high manufacturing costs, while sine-wave motors have complex control systems and reduced force parameters, limiting their applications. Additionally, square-wave brushless DC motors have seen little research due to their inefficiencies, especially at high speeds.
Innovation Solution
A broad-pole type square-wave three-phase brushless permanent magnet direct current motor with 2P=4 poles, featuring a rotor core with alternating permanent magnets and a stator core with six teeth, including three large and three small teeth, where windings are concentrated and arranged in a specific pattern to minimize torque fluctuations and reduce manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If square-wave permanent magnet motor is used, then control simplicity is improved, but switching torque fluctuation increases
Solution Approach 1:
The patent changes the pole pair number parameter to 2P=4 (broad-pole configuration) and uses concentrated windings instead of distributed windings. This parameter change transforms the torque waveform characteristics, reducing switching torque fluctuation while maintaining square-wave control simplicity. The specific configuration of 4 poles with concentrated windings creates a more favorable magnetic field distribution that diminishes torque ripple.
2Stability of the object's composition
If sine-wave permanent magnet motor is used, then moment fluctuation is reduced, but control system complexity increases
Solution Approach 1:
The patent adopts a pole pair number of 2P=4 and concentrated winding configuration, which fundamentally changes the motor's electromagnetic characteristics. This parameter selection enables the motor to achieve low moment fluctuation similar to sine-wave motors while being compatible with simple square-wave control, thus avoiding the complexity of sine-wave control systems.
3Stability of the object's composition
If sine-wave permanent magnet motor is used, then moment fluctuation is reduced, but manufacturing cost increases
Solution Approach 1:
The patent specifies a pole pair number of 2P=4 and uses concentrated windings, which simplifies the manufacturing process. The concentrated winding structure requires fewer manufacturing steps and lower cost compared to distributed windings, while the specific pole configuration achieves moment stability comparable to sine-wave motors.
4Ease of operation
If square-wave brushless DC motor is used, then control simplicity is maintained, but iron loss increases at high speed
Solution Approach 1:
The patent uses a pole pair number of 2P=4 and concentrated windings, which creates a more favorable magnetic field distribution. This configuration reduces harmonic content and improves magnetic field smoothness, thereby reducing iron losses at high speeds while maintaining the simplicity of square-wave control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The motor achieves a 33% greater force output than sine-wave permanent magnetic servo motors with reduced copper consumption and stable moment fluctuations, while maintaining a simplified structure and low manufacturing costs, comparable to sine-wave motors in performance.
Implementation Method 1
a rotor core provided with a plurality of pairs of permanent magnets thereon, and a stator slot provided with three phases of windings therein
Implementation Method 2
the motor comprising a rotor core provided with a plurality of pairs of permanent magnets thereon, and a stator slot provided with three phases of windings therein
Data Source
AI summary
A broad-pole type square-wave three-phase brushless permanent magnet direct current motor and an assembling method thereof are disclosed. The number of magnetic poles on a rotor core is: 2P=4. The number of slots in a stator core is: Z=6. Six teeth on the stator are composed of three large teeth and three small teeth. The sum of mechanical angels of one large tooth and one small tooth is 120 degree. Electrical angles corresponding to the mechanical angles are: P* 120=240° . Three-phase concentrated windings are wound on three large teeth separately, and only one winding is arranged at each phase. The advantages of the motor are low positioning torque, simple structure, effective production cost, convenient to wind the windings, and low copper loss, etc.