Converter-fed Linear Motor Pole Pitch Matching
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Solution Overview
Problem
Short stroke linear motors used in machine tools for eccentric turning face limitations in achieving high dynamics due to the constraint of minimizing the mass of the secondary part, leading to suboptimal motor force and machining speed, especially in applications requiring precise and small stroke movements.
Innovation Solution
The design of a short stroke linear motor with a single-strand or two-strand winding in the primary part, where the first and second pole pitches are essentially equal, allowing for improved drive dynamics by optimizing the phase difference between the primary and secondary parts, enabling higher motor force production within the same installation space and mass, and utilizing a three-phase converter or DC regulator for efficient power supply.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the mass of the secondary part is minimized by optimizing geometry and stiffness, then the motor dynamics are improved, but the design becomes technically elaborate with complex machining and expensive materials
Solution Approach 1:
The patent changes the fundamental parameter of pole pitch equality between primary and secondary parts, and modifies the winding configuration to single-strand or two-strand. This parameter change allows achieving high motor force (up to 173% of nominal force) without requiring complex secondary part designs, thus improving motor dynamics while avoiding elaborate design and expensive materials
2Duration of action of moving object
If a three-phase synchronous linear motor is used with multiple strands, then the motor operates continuously, but the force utilization is suboptimal as not all strands are in optimum pole position simultaneously
Solution Approach 1:
The patent extracts the unnecessary complexity of multi-strand windings and reduces the system to a single-strand or two-strand configuration. By taking out the redundant strands that cannot simultaneously be in optimal position, the patent achieves both continuous operation through proper commutation and optimal force utilization from the simplified winding structure
Solution Approach 2:
The patent changes the winding parameter from multi-strand to single-strand or two-strand configuration, and equalizes the pole pitches. This parameter change enables the motor to achieve up to 173% of nominal force while maintaining continuous operation capability through converter-fed control
3Speed
If the secondary part mass is minimized, then the motor dynamics improve, but the motor force is reduced
Solution Approach 1:
The patent applies parameter changes by equalizing the pole pitches of primary and secondary parts and adopting single-strand or two-strand windings. These parameter changes enable the motor to generate up to 173% of nominal force while maintaining minimal secondary part mass, thus simultaneously achieving high motor dynamics and high motor force
Solution Approach 2:
The patent employs converter-fed control with adjustable commutation position, enabling dynamic optimization of the motor operation. This dynamic control strategy allows the motor to maintain optimal performance across different operating conditions while keeping the secondary part mass minimal
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
This configuration enhances motor dynamics and machining speed by achieving up to 173% of the nominal force with reduced power loss and eliminates zero-force positions, allowing for reliable operation over a larger range of travel without additional manufacturing costs or complexity.
Implementation Method 1
The primary part (12) has a single-strand winding or a two-strand winding
Implementation Method 2
a first pole pitch and a secondary part (11) having a second pole pitch, the first pole pitch and the second pole pitch being essentially equal
Data Source
AI summary
The invention relates to a short stroke linear motor. In order to improve the dynamics of such a short stroke linear motor, the primary part (12) of the motor is provided with a single-strand winding. The primary part (12) and the secondary part (1) have essentially the same pole pitch (tZ=tM). In this way, a very high motor torque is produced in a limited range of displacement. In order to be able to reach a plurality of working positions without an inactive intermediate position, a short stroke linear motor having a double-strand winding is additionally provided, both strands being operated at a phase difference of <90°. The pole pitch of the primary part and the secondary part are again essentially the same.