Electric Power Converter Neutral Current Control
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Solution Overview
Problem
State-of-the-art electric power converters with through neutral connections require high capacitance values for filtering, leading to increased costs and inefficiencies due to unbalanced neutral currents, which are not effectively controlled by existing control devices, resulting in power losses and reduced electrical efficiency.
Innovation Solution
A control device for electric power converters that includes a common neutral conductor connected between the DC voltage lines and an additional common stage with electronic power components, allowing for independent control of neutral currents and enabling over-modulation to reduce capacitor size and switching losses, using a processing unit to generate modulation signals based on a reference voltage and common control components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high capacitance values are used for filtering DC voltage in converters with through neutral connections, then voltage stability is improved, but device cost and size increase
Solution Approach 1:
The patent divides the single neutral current control function into two independent control paths: one for inverter neutral currents and one for rectifier neutral currents. This segmentation allows each converter stage to be controlled independently, enabling reduced capacitor sizing while maintaining voltage stability through coordinated control of both stages.
Solution Approach 2:
The patent implements dynamic control of neutral currents through adjustable modulation signals that can adapt to varying load conditions. The control device dynamically adjusts the neutral current components from both rectifier and inverter based on real-time operating conditions, replacing the static high-capacitance filtering approach with an active dynamic compensation method.
2Device complexity
If neutral currents are not controlled in converters with through neutral connections, then device complexity is reduced, but power losses increase due to unbalanced neutral currents
Solution Approach 1:
The control device performs multiple functions simultaneously: it controls the semiconductor stages for power conversion, generates specific modulation signals for neutral current control, and coordinates both rectifier and inverter operations. This multi-functionality integrates neutral current control into the existing control architecture without requiring completely separate control systems.
Solution Approach 2:
The patent changes the modulation parameters of the semiconductor stages to achieve neutral current control. By adjusting the modulation signals applied to the semiconductor devices, the control device can independently regulate neutral current components from both rectifier and inverter, thereby reducing power losses through parameter optimization rather than additional hardware.
3Loss of energy
If a common neutral conductor is used between input and output, then electrical efficiency is improved through better current balancing, but control complexity increases
Solution Approach 1:
The control device uses feedback from the common neutral conductor to adjust the modulation signals for both rectifier and inverter. By monitoring the neutral current and using this information to dynamically adjust control parameters, the system achieves automatic current balancing that improves electrical efficiency while keeping the control architecture manageable through self-regulation.
Data Source
AI summary
An electric power converter with a control device that comprises a processing unit receives control signals and sends modulated signals to inverter stages of the electric power converter. The control device also controls a common stage of the electronic power converter, which is connected between power lines and a common neutral connection. The signals to the common stage are outputted based on inputs from a modulation signal and a reference voltage signal.