Asynchronous Machine Control for Intermediate Circuit Current Optimization
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Solution Overview
Problem
Asynchronous machines with multiple stator windings face challenges in minimizing the load on intermediate circuit capacitors, leading to increased component sizes and inefficiencies in power management.
Innovation Solution
A method and device that control the partial converters of asynchronous machines with multiple stator windings by determining a second degree of modulation based on the intermediate circuit voltage, optimizing the effective value of the intermediate circuit current to minimize load on capacitors, using a table or characteristic map to ensure reliable operation and low capacitor current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional control methods are used for asynchronous machines with multiple stator windings, then the machine can operate reliably, but the intermediate circuit capacitor experiences high load leading to increased component sizes
Solution Approach 1:
The patent applies dynamic control by continuously adjusting the modulation degrees of multiple partial converters based on real-time operating conditions. The control device dynamically determines first and second modulation degrees for first and second partial converters respectively, optimizing the intermediate circuit current in real-time to reduce capacitor load while maintaining reliable machine operation.
Solution Approach 2:
The patent changes key control parameters (modulation degrees) to optimize system performance. By determining modulation degrees as functions of operating parameters and optimizing the effective value of intermediate circuit current, the system reduces capacitor stress without compromising reliability, thereby allowing smaller capacitor sizes.
2Productivity
If multiple partial converters are used to control multiple stator windings, then the machine performance is improved, but the intermediate circuit current increases leading to higher capacitor load
Solution Approach 1:
The control device dynamically coordinates multiple partial converters by determining specific modulation degrees for each converter based on operating conditions. This dynamic coordination allows the system to maintain high productivity through multiple stator windings while optimizing the intermediate circuit current waveform to reduce its effective value and capacitor load.
Solution Approach 2:
The patent optimizes control parameters (modulation degrees) of multiple partial converters to reduce energy losses. By adjusting the first and second modulation degrees as functions of operating parameters, the system maintains improved machine performance while minimizing the effective value of intermediate circuit current, thereby reducing capacitor load and energy losses.
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 results in a significantly reduced effective value of the intermediate circuit current, allowing for the use of smaller capacitors and ensuring efficient operation of the asynchronous machine with minimal load on the intermediate circuit capacitor.
Implementation Method 1
a common intermediate circuit, which has an intermediate circuit capacitor
Implementation Method 2
The first stator winding is fed via a first partial converter and the second stator winding is fed via a second partial converter
Data Source
Figure 1~3
Figure 2
Figure 4A~4B
AI summary
The method involves controlling partial converters for determining a modulation factor based on another modulation factor. The former modulation factor is determined such that the former modulation factor is optimized, during controlling of an asynchronous machine with respect to a low root mean square value of current in an intermediate circuit. The current is supplied from the intermediate circuit to the partial converters. An actual value of an operational parameter is equalized to a reference value of the operational parameter, under consideration of auxiliary condition. An independent claim is also included for a device for operating an asynchronous machine.