Parallel Switching Unit Synchronization in Injection Moulding Drives
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Solution Overview
Problem
Injection molding machines face challenges in achieving precise control of output currents from switching units connected in parallel, leading to the need for large and expensive chokes to compensate for current differences, which limits scalability and increases costs.
Innovation Solution
The solution involves connecting outputs of switching units via lines that pass through smoothing inductance elements, with a correction controller synchronizing switching times to align output currents, potentially eliminating the need for large chokes by using smaller inductance elements and adjusting control signals to synchronize switching edges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large chokes with high inductance are used to compensate for current differences in parallel-connected switching units, then current stability is improved, but device size and cost increase
Solution Approach 1:
The patent applies preliminary action by synchronizing the switching times of switches in parallel-connected switching units before current differences can cause instability. The control system adjusts switching patterns to ensure simultaneous switching edges, preventing current pulses from occurring at different times. This proactive synchronization eliminates the need for large chokes to compensate for timing differences, achieving current stability without increasing device size.
2Device complexity
If switching times of parallel-connected switching units are not synchronized, then current differences occur requiring large chokes, but synchronizing switching times requires complex control
Solution Approach 1:
The patent implements feedback by continuously monitoring the switching states and current outputs of parallel-connected switching units. The control system measures actual switching times and compares them against synchronized timing targets, then adjusts control signals to correct any deviations. This closed-loop feedback mechanism ensures precise current synchronization while using straightforward control logic that does not significantly increase system complexity.
3Power
If switching units are connected in parallel to distribute energy flows, then power handling capability increases, but current control precision decreases
Solution Approach 1:
The patent applies merging by combining multiple switching units in parallel while implementing a unified control strategy that treats them as a single synchronized system. The control system generates coordinated switching patterns for all parallel units, ensuring they operate in unison with synchronized edges. This merging approach allows the system to handle high power through parallel connection while maintaining current control precision through unified synchronization 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
This approach reduces the size and cost of chokes required, enhances precision in current control, and allows for more scalable and universally applicable switching units, improving the efficiency and adaptability of injection molding machines.
Implementation Method 1
at least one correction controller configured to synchronize switching times, in particular the switching edges, of switches assigned to corresponding outputs, so that they switch simultaneously
Implementation Method 2
corresponding outputs of the switching units are connected via lines which pass through smoothing inductance elements
Data Source
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AI summary
The invention relates to an injection moulding machine (1) comprising: an electric machine (2); multiple switching units (8) electrically connected in parallel, wherein each switching unit (8) has at least one electrical output (9) and at least one electrical switch associated with the output (9), which can be switched according to a switching pattern, wherein corresponding outputs (9) of the switching units (8) are electrically connected in parallel with a common output (10); at least one primary open-loop and/or closed-loop controller (14) which is designed to control the switching units (8) with control signals in order to operate the electric machine (2); a measuring device (15) for measuring output currents (lu1- Iw3) at the outputs (9); and at least one correction controller (24) which is designed to adjust a corresponding control signal (13) in the event of a deviation between a measured output current (lu1- Iw3) at an output (9) and a target value (S), such that switching times - specified by the switching pattern - of the at least one switch, which is associated with the relevant output (9), are temporally shifted forwards or backwards, wherein the at least one correction controller (24) is designed to synchronise switching times, in particular the switching edges, of switches (30) associated with corresponding outputs (9), such that they switch simultaneously.