Stator Device with DC-DC Converters for Linear Motor Overvoltage Control
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Solution Overview
Problem
In linear motor systems, sudden increases in intermediate circuit voltage due to energy feedback during braking can lead to overvoltage, causing the motor to be switched off for safety, resulting in downtime and potential damage, especially in dynamic applications with multiple carriages and high loads, where external choppers can become overloaded.
Innovation Solution
The integration of drive coils with separate DC-DC converters forms a bridge circuit, allowing for independent regulation of energy dissipation from the intermediate circuit into the drive coils, thereby controlling and reducing overvoltage, without the need for external choppers or special braking resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external chopper devices are used to dissipate excess energy during braking, then overvoltage protection is provided, but the chopper devices can become overloaded in dynamic applications with high loads
Solution Approach 1:
The patent divides the energy dissipation function across multiple drive coils instead of using a single external chopper device. Each drive coil can independently absorb regenerative energy during braking, segmenting the power handling capacity across several parallel paths and preventing overload of any single device.
Solution Approach 2:
The drive coils serve dual functions: they perform their primary motor drive function during normal operation and simultaneously function as energy absorption elements during braking. This eliminates the need for separate dedicated chopper devices and utilizes existing components for multiple purposes.
2Device complexity
If drive coils are used to dissipate energy during braking, then system complexity is reduced by eliminating external choppers, but independent regulation of energy dissipation is required
Solution Approach 1:
The control system continuously monitors the voltage on the DC link and the state of each drive coil, using this feedback information to dynamically determine which coils should absorb energy and at what rate. This closed-loop control enables independent regulation of energy dissipation despite the simplified hardware architecture.
Solution Approach 2:
The system dynamically adjusts the function of each drive coil based on real-time operating conditions. During braking, the control system can selectively activate specific coils for energy absorption while keeping others available for motor function, allowing flexible and independent control of energy dissipation patterns.
3Reliability
If multiple drive coils are used for energy dissipation, then reliability is improved through redundancy, but coordination control becomes more complex
Solution Approach 1:
The control system activates only the necessary number of drive coils for energy dissipation based on the current energy level on the DC link, rather than using all available coils simultaneously. This partial action approach maintains reliability through available redundancy while simplifying control coordination by limiting the number of actively controlled elements at any given time.
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 solution efficiently dissipates excess energy, preventing overvoltage and avoiding motor shutdowns, thus ensuring continuous operation and protecting electrical components, while avoiding the need for system upgrades or retrofits.
Implementation Method 1
dissipating electrical energy, which corresponds to an overvoltage in the intermediate circuit, into the drive coils
Data Source
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AI summary
The invention relates to a stator device (201) for a linear motor (201; 407), comprising: - several drive coils (241, 245), - each of which is electrically connected to an intermediate circuit (203) by means of its own DC-DC converter (261, 263), - so that electrical energy can be fed from the intermediate circuit (203) into the respective drive coil (241, 245) or electrical energy can be fed from the respective drive coil (241, 245) into the intermediate circuit (203) by means of the respective DC-DC converter (261, 263), - a voltage measuring device (211) for measuring an electrical intermediate circuit voltage, - a control device (249) for controlling the DC-DC converters (261, 263), - wherein the control device (249) is configured to control at least one of the DC-DC converters (261, 263) in such a manner to control the transfer of electrical energy from the intermediate circuit (203) into the controlled DC-DC converter (261,263) corresponding drive coil (241, 245) is supplied when the measured DC link voltage is greater than or greater than or equal to a predetermined DC link voltage threshold. The invention further relates to a linear drive system (401), a method for operating a stator device (201) and a computer program.