Modular Power Converter Linear Submodule Harmonic Control
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Solution Overview
Problem
Existing modular power converters face challenges in minimizing interference currents while maintaining efficiency, as even with multilevel topologies, small step heights require a large number of stages to meet EMC limits, and linear amplifiers suffer from high power dissipation and low efficiency.
Innovation Solution
The method involves operating at least one submodule in series in linear mode within the converter valves, allowing for precise voltage control with low losses, and dynamically reallocating linear operation among submodules based on criteria like temperature and power loss to distribute heating evenly and extend service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a multilevel topology with many submodules is used to reduce interference currents, then interference currents are reduced proportionally to the number of steps, but the device complexity and cost increase significantly
Solution Approach 1:
The patent applies partial action by using only one submodule in linear mode instead of requiring all submodules to be in linear mode. This selective approach achieves the necessary interference current reduction while avoiding the complexity of having all submodules operate in linear mode, thus resolving the contradiction between interference current reduction and device complexity.
Solution Approach 2:
The patent changes the operational parameter of submodules by switching between switched mode and linear mode. By dynamically changing the operating state of at least one submodule to linear mode during specific time intervals, the system achieves reduced interference currents without permanently increasing device complexity.
2Object-generated harmful factors
If linear amplifiers with MOSFETs are used to provide precise sinusoidal voltage, then interference currents are minimal, but power dissipation is very high and efficiency is below 30%
Solution Approach 1:
The patent uses linear mode operation only partially - specifically, only one submodule operates in linear mode while others operate in switched mode. This partial application of linear mode achieves sufficient interference current reduction without the excessive power dissipation that would occur if all submodules operated in linear mode, thus resolving the contradiction between minimal interference currents and high power dissipation.
Solution Approach 2:
The patent applies different operational qualities to different submodules: one submodule operates in linear mode to provide precise voltage control and minimize interference, while other submodules operate in switched mode to maintain high efficiency. This local differentiation resolves the contradiction by optimizing each submodule's function according to its role in the overall system.
3Manufacturing precision
If submodules operate in linear mode for precise voltage control, then sinusoidal output is achieved, but heating increases and service life decreases
Solution Approach 1:
The patent limits linear mode operation to only one submodule at a time, thereby achieving the necessary voltage control precision while minimizing the total heating generated. By not requiring all submodules to operate in linear mode simultaneously, the system achieves precision without excessive temperature increase, resolving the contradiction between voltage control precision and submodule heating.
Solution Approach 2:
The patent dynamically switches which submodule operates in linear mode based on temperature conditions. When a submodule's temperature exceeds a threshold, the system switches to another submodule, allowing the heated submodule to cool down. This dynamic adaptation resolves the contradiction by maintaining voltage control precision while managing temperature to preserve service life.
4Ease of operation
If the same submodule continuously operates in linear mode, then voltage control is simplified, but that submodule experiences excessive heating and reduced service life
Solution Approach 1:
The patent implements dynamic switching between submodules based on temperature thresholds. When a submodule's temperature exceeds the threshold during linear mode operation, the control unit switches to another submodule, allowing the heated one to cool down. This dynamic approach maintains operational simplicity while distributing thermal stress, thus resolving the contradiction between control simplicity and submodule service life.
Solution Approach 2:
The patent uses temperature feedback to control submodule operation. The control unit monitors the temperature of submodules and dynamically adjusts which submodule operates in linear mode based on real-time temperature conditions. This feedback mechanism resolves the contradiction by maintaining ease of operation through automated control while preventing excessive heating and extending service life.
Data Source
Figure 1
AI summary
The invention relates to a method for operating a modular power converter (1) with a plurality of submodules (20, 30), wherein the modular power converter (1) generates an alternating voltage at at least one AC-side terminal (12) by switching operations of power semiconductors of the submodules (20, 30), wherein at least one submodule (30) arranged between the AC-side terminal (12) and a positive terminal of an intermediate circuit (15), and at least one submodule (30) arranged between the AC-side terminal and a negative terminal of an intermediate circuit (15), are operated in linear mode. The invention further relates to a modular power converter (1) with a plurality of submodules (20, 30) for carrying out the method according to the invention.