Modular Brake Actuator Circuit for DC-Link Harmonic Suppression
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Solution Overview
Problem
Existing modular braking units face challenges in achieving stable energy balance and preventing voltage fluctuations, particularly in medium- and high-voltage applications, which can lead to harmonic loading of the DC link.
Innovation Solution
A modular braking unit design featuring a first and second submodule group with a braking resistor in series, and a parallel series circuit with a capacitor and additional resistor, where alternating voltage components are antiphased to prevent alternating currents, allowing independent control of direct and alternating power components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a modular braking unit with submodule groups is used to enable targeted energy dissipation, then the adaptability for medium- and high-voltage applications is improved, but voltage fluctuations and harmonic loading of the DC link occur due to alternating currents in the submodule groups
Solution Approach 1:
The patent extracts the alternating current component from the submodule groups by introducing a parallel circuit with capacitor and braking resistor. This separate path allows the AC component to be diverted and dissipated independently, preventing it from causing voltage fluctuations and harmonic loading on the DC link while maintaining the modular structure's adaptability.
Solution Approach 2:
The patent introduces a parallel circuit comprising a capacitor and braking resistor as an intermediary element. This intermediate circuit acts as a mediator that receives the alternating current component from the submodule groups, filters it through the capacitor, and dissipates it safely through the braking resistor, thereby protecting the DC link from harmonic loading.
2Power
If alternating voltage components are generated by submodule groups for energy dissipation, then power conversion capability is improved, but alternating currents are formed that cause harmonic loading
Solution Approach 1:
The patent converts the harmful alternating current into a beneficial controlled dissipation path. By providing a dedicated parallel circuit with capacitor and braking resistor, the AC component that would otherwise cause harmonic loading is instead channeled into a controlled path where it is safely dissipated as heat in the braking resistor, transforming a harmful effect into a manageable and even useful energy dissipation mechanism.
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 design ensures stable operation by maintaining energy balance, preventing alternating currents, and allowing independent control of power conversion, thus stabilizing the modular braking unit and reducing harmonic interference.
Implementation Method 1
A capacitor is advantageously used to suppress the direct current
Implementation Method 2
the resistance of a brake actuator assembly is often also referred to as a braking resistor, as it is suitable for converting electrical energy generated by an electrical machine during braking into heat
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
The invention relates to a modular braking actuator (1) with submodules (2). To improve the modular braking actuator (1), it is proposed that a first submodule group (21), a second submodule group (22), and a braking resistor (3) are arranged in a first series circuit (14) between two terminals (13) of the modular braking actuator (1), wherein the braking resistor (3) is electrically arranged between the first submodule group (21) and the second submodule group (22), wherein the first submodule group (21) and the second submodule group (22) each have at least one submodule (2), a further braking resistor (31), and a capacitor (7), wherein a second series circuit (15) comprising the further braking resistor (31) and the capacitor (7) is arranged electrically parallel to at least one submodule (2) of the at least one submodule (2).The invention further relates to a modular drive unit (10) comprising a modular multilevel power converter (11) and such a modular braking unit (1), wherein the multilevel power converter (11) is connected to the modular braking unit (1) on the DC voltage side. The invention further relates to an operating method for such a modular braking unit (1) or for such a modular drive unit (10), wherein a first AC voltage component (uBR,AC,1) is generated by the submodules (2) of the first submodule group (21) and a second AC voltage component (uBR,AC,2) is generated by the submodules (2) of the second submodule group (22), wherein the first AC voltage component (uBR,AC,1) and the second AC voltage component (uBR,AC,2) are in phase opposition to one another.