Arrangement and method for testing an inverter and/or a converter
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Solution Overview
Problem
Conventional power electronics for testing inverters and converters require complex and expensive hardware structures to achieve high bandwidth and current control accuracy, leading to high switching losses and low power density, especially when emulating high currents and dynamic reactions in systems like wind power plants and electric vehicles.
Innovation Solution
A system comprising a first emulation device with current-optimized load modules and a second emulation device with dynamics-optimized load modules, connected in parallel, controlled by a control device to filter output voltages for accurate emulation of motor current fundamental waves and ripples, using DC link capacitors to reduce complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional fast-switching current-controlled multilevel converters are used as load modules to achieve high bandwidth and current control accuracy, then the reproduction of motor current ripples is improved, but the switching losses increase and the current per volume decreases
Solution Approach 1:
The system is divided into multiple load modules (first and second load modules) that can be independently controlled. Each module handles specific frequency ranges, allowing the system to achieve high current control accuracy across different bands while managing switching losses through selective operation of each segment.
Solution Approach 2:
Different load modules are optimized for different local frequency ranges. The first load module handles lower frequency components while the second load module handles higher frequency ripple components, allowing each module to operate in its optimal performance region with appropriate switching frequencies.
2Speed
If the switching frequency of load modules is increased to achieve high bandwidth for current ripple reproduction, then the dynamics response is improved, but the switching losses increase and cooling effort increases
Solution Approach 1:
The system uses periodic pulse width modulation at different frequencies for different load modules. The first load module operates at a lower switching frequency for fundamental current components, while the second load module operates at a higher switching frequency for ripple components, achieving high bandwidth without excessive switching losses in all modules simultaneously.
3Quantity of substance
If multiple load modules are connected in parallel to increase the total current capability, then the current capacity is improved, but the device complexity increases
Solution Approach 1:
Each load module is designed to perform multiple functions: the first load module handles both fundamental current and some ripple components, while the second load module complements it for high-frequency ripple handling. This multi-functional design allows parallel connection to increase current capacity while keeping each module relatively simple and standardized.
4Speed
If load modules are optimized for maximum dynamics with high switching frequency, then the reproduction of motor current ripples is improved, but the realizable current per volume decreases
Solution Approach 1:
The system segments the current spectrum into different frequency bands handled by different load modules. The first load module handles lower frequency components with higher current capacity, while the second load module handles high-frequency ripple components with smaller current magnitude, achieving both high dynamics response and high current per volume in the overall system.
Data Source
AI summary
A system for testing an inverter and/or a converter includes: a first emulation device configured to emulate a power generator; a second emulation device configured to emulate a power consumer; and a control device. The first emulation device comprises at least one first current-optimized load module. The second emulation device comprises at least one parallel circuit composed of a second dynamics-optimized load module and a second current-optimized load module. The first current-optimized load module and the second current-optimized load module each comprise an at least two-stage inverter. The second dynamics-optimized load module comprises an at least three-stage inverter. The control device is configured to: control the second current-optimized load module based on a low-pass-filtered output voltage of the inverter and/or the converter; and control the second dynamics-optimized load module based on a high-pass-filtered output voltage of the inverter and/or the converter.