Linear Motor Stator Overvoltage Protection via Drive Coil Energy Diversion
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Solution Overview
Problem
In linear motor systems, abrupt braking leads to energy feedback into the intermediate circuit, causing an overvoltage that can overload external chopper devices, resulting in deactivation of the motor for safety reasons and potential downtime.
Innovation Solution
A stator device with multiple drive coils connected to their own DC voltage converters allows for controlled diversion of excess energy from the intermediate circuit into the drive coils, regulating the direct current to manage overvoltage, thereby preventing motor deactivation and maintaining system efficiency without the need for additional braking resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an external chopper device is used to dissipate excess energy during braking, then the intermediate circuit voltage can be controlled, but the chopper device may become overloaded, leading to motor deactivation and downtime
Solution Approach 1:
The patent merges the chopper function with the existing DC voltage converters that are already connected to each drive coil. Instead of using a separate external chopper device, the patent utilizes the existing converter infrastructure to divert excess energy from the intermediate circuit into the drive coils, thereby eliminating the need for additional external chopper hardware while maintaining overvoltage protection capability
Solution Approach 2:
The system uses its own existing components (DC voltage converters and drive coils) to handle the braking energy dissipation. The converters that are already present for motor control are repurposed to also function as chopper devices, allowing the system to serve itself rather than requiring external assistance for overload protection
2Object-affected harmful factors
If braking resistors are connected to dissipate energy, then overvoltage can be prevented, but additional components and system complexity are required
Solution Approach 1:
Instead of dissipating braking energy as waste heat through resistors, the patent converts the harmful excess energy into useful work by storing it in the drive coils' magnetic fields. The energy that would normally be lost is now reused to maintain motor operation, transforming a harmful overvoltage condition into a beneficial energy recovery opportunity
Solution Approach 2:
The DC voltage converters are designed to perform multiple functions: normal motor control during operation and energy diversion during braking. This multi-functionality eliminates the need for separate braking resistor connections, as the same converters handle both propulsion and energy dissipation tasks
3Reliability
If the external chopper resistor is not loaded during overload, then the chopper device is protected, but overvoltage is detected and the linear motor is deactivated
Solution Approach 1:
The patent segments the energy diversion capability across multiple independent DC voltage converters, each connected to its own drive coil. Instead of relying on a single external chopper resistor, the system distributes the braking energy absorption across several converter-coil pairs, providing redundant pathways for energy dissipation and preventing single-point failure that would cause motor deactivation
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 effectively counters overvoltage in the intermediate circuit, preventing motor deactivation and reducing downtime by allowing controlled energy diversion into drive coils, thus protecting electrical components and maintaining efficient operation of the linear motor system.
Implementation Method 1
by the respective DC voltage converter, electrical energy may be fed from the intermediate circuit into the respective drive coil, or electrical energy may be fed from the respective drive coil into the intermediate circuit
Implementation Method 2
multiple drive coils, which are respectively electrically conductively connected to an intermediate circuit by their own DC voltage converter
Data Source
AI summary
A linear motor comprises a stator, the stator comprising multiple drive coils and an intermediate circuit electrically conductively connected to each drive coil, the intermediate circuit being configured to exchange energy with each drive coil. The drive coils are arranged along the running rail, where at least one slide comprising a magnet acting as a rotor of the linear motor is movably arranged on the running rail. A controller is configured to independently control each drive coil, so that electrical energy is fed from the intermediate circuit into the drive coils, if a measured intermediate circuit voltage is greater or equal to a predetermined intermediate circuit voltage threshold value, where those drive coils are excluded from the feed-in of the electrical energy which are instantaneously being used for driving or braking the at least one slide and/or have a thermal load which exceeds a predetermined thermal load threshold value.