Half-Bridge Control for Long Stator Linear Motor Coil Polarity
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Solution Overview
Problem
The high cost and circuit complexity of controlling long-stator linear motor (LLM) coils due to the requirement of multiple switches in full bridge configurations, which is necessary for changing the polarity of the coil voltage.
Innovation Solution
A method using half-bridges with two switches per LLM coil, where the midpoint of each half-bridge is connected to a control point, allowing for polarity change by controlling the switches to apply different potentials, reducing the number of switches needed and simplifying the circuitry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If full bridge configurations are used to control LLM coils, then the ability to change coil voltage polarity is ensured, but the number of switches increases and circuit complexity increases
Solution Approach 1:
The full bridge configuration is segmented into two separate half-bridge circuits. Each half-bridge contains only two switches instead of four, reducing the switch count per coil from 4 to 2. The two half-bridges work in coordination to achieve the same polarity reversal function as a complete full bridge, thereby simplifying the circuit while maintaining full functionality.
2Adaptability or versatility
If full bridge configurations are used to control LLM coils, then the ability to change coil voltage polarity is ensured, but costs increase due to larger number of switches
Solution Approach 1:
The full bridge configuration is segmented into two separate half-bridge circuits. Each half-bridge contains only two switches instead of four, reducing the switch count per coil from 4 to 2. The two half-bridges work in coordination to achieve the same polarity reversal function as a complete full bridge, thereby simplifying the circuit while maintaining full functionality.
3Device complexity
If half-bridges with control point regulation are used, then the number of switches is reduced, but a larger operating voltage difference is required
Solution Approach 1:
A control point with potential regulation is introduced as an intermediary element between the two half-bridges. This control point actively regulates its potential to enable proper voltage application across the coil. The regulation mechanism compensates for the higher voltage difference requirement by dynamically adjusting the control point potential to maintain correct coil voltage polarity and magnitude.
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 approach reduces the number of switches by half, lowering costs and complexity while maintaining the ability to change coil voltage polarity, with the potential advantage of requiring a greater operating voltage difference.
Implementation Method 1
a control unit is provided which is designed to regulate an actual potential of the control point to a predetermined potential
Implementation Method 2
These LLM coils are driven individually or in groups, and during operation of the long-stator linear motor, it is often desirable or necessary to reverse the polarity, i.e., the current direction of the LLM coils. Driving the LLM coils generates a moving magnetic field, which interacts with excitation magnets (usually permanent magnets) on a transport unit of the LLM to move the transport unit along the stator
Data Source
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AI summary
In order to specify a method and a device for controlling the n LLM coils (L1,...ln) of an LLM stator, which allows the polarity of the coil voltage (UL1,...,ULn) of the n LLM coils (L1,...,Ln) to be changed with less effort and in a circuit-technically simple way, it is proposed to apply a first operating potential (Ub1) to n first input terminals (A1,...,An) of n half-bridges (HB1,...,HBn), and a second operating potential (Ub2) to n second input terminals (B1,...Bn) of the n half-bridges. For each half-bridge (HB1,...,HBn), a first switch (S11,...S1n) is connected between a midpoint (C1,...,Cn) of the respective half-bridge (HB1,...,HBn) and the first input terminal (A1,..., An), and a second switch (S21,...,S2n) is connected between the midpoint (C1,...,Cn) of the respective half-bridge (HB1,...,HBn) and the second input terminal (B1,...,Bn). The midpoint (C1,...,Cn) of the n half-bridges is connected to n first terminals (L11,...,L1n) of the n LLM coils (L1,...,Ln) are connected, the second connections (L11,...,L1n) of the n LLM coils (L1,...,Ln) are connected in a control point (C) which is controlled to a predetermined potential (Ux).