Inverter T-Filter Reactor Windings for Phase Angle Control
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Solution Overview
Problem
Existing inverter topologies face challenges in accurately controlling the phase angle between output current and voltage to meet newer grid connection standards, leading to increased complexity, cost, and efficiency losses, especially when providing reactive power.
Innovation Solution
Incorporating additional windings on the mains-side series reactors of the T-filter to generate signal voltages proportional to the phase conductors' currents, allowing for precise determination and adjustment of the phase angle, thereby enabling accurate specification of reactive power components with reduced circuit complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional current sensors are inserted into the phase conductors to accurately measure current for phase angle control, then measurement precision is improved, but device complexity and manufacturing cost increase significantly
Solution Approach 1:
The series reactors serve dual functions: their primary function as filtering components and their secondary function as current sensing elements through additional windings. This multi-functionality eliminates the need for separate current sensors, reducing device complexity while maintaining measurement precision for phase angle control
Solution Approach 2:
The patent combines the current sensing function with the existing series reactors by adding windings to them. This merging of functions integrates the measurement capability into the filtering structure, avoiding additional components and reducing overall system complexity
2Measurement precision
If additional current sensors are inserted into the phase conductors to accurately measure current for phase angle control, then measurement precision is improved, but manufacturing cost increases significantly
Solution Approach 1:
The series reactors serve dual functions: their primary function as filtering components and their secondary function as current sensing elements through additional windings. This multi-functionality eliminates the need for separate current sensors, reducing device complexity while maintaining measurement precision for phase angle control
Solution Approach 2:
The patent combines the current sensing function with the existing series reactors by adding windings to them. This merging of functions integrates the measurement capability into the filtering structure, avoiding additional components and reducing overall system complexity
3Adaptability or versatility
If the inverter topology is modified to enable reactive power capability, then adaptability is improved, but device complexity and efficiency losses increase
Solution Approach 1:
The patent implements feedback control by measuring the actual phase angle between voltage and current using the series reactor windings and adjusting the inverter bridge switching accordingly. This feedback mechanism enables precise reactive power control without requiring complex topology modifications, maintaining adaptability while controlling device complexity
Solution Approach 2:
The patent achieves reactive power capability by controlling the phase angle parameter between voltage and current. By adjusting this parameter through simple bridge switching control based on measured phase angle, the inverter can provide reactive power without modifying its fundamental topology, thus improving adaptability while minimizing complexity increases
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 solution allows for high-accuracy control of reactive power with lower costs and complexity, as the additional windings require fewer turns and can be implemented more economically compared to using additional current sensors.
Implementation Method 1
the mains-side series reactors of the T-filter each have an additional winding from which a signal voltage for influencing the inverter bridge can be taken. The series reactors on the mains side form a transformer with the additional windings in each phase conductor, from which a signal voltage can be taken that is proportional to the current on the associated phase conductor.
Data Source
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AI summary
Inverter with an inverter bridge that generates a single- or multi-phase AC voltage, which can be connected to an AC power grid via one or more phase conductors and a neutral conductor, and with a T-filter downstream of the inverter bridge, consisting for each phase conductor of two series-connected chokes, at the connection point of which one terminal of a capacitor is connected, the second terminal of which is connected to the neutral conductor, wherein the grid-side series chokes of the T-filter each have an additional winding, from which a signal voltage for influencing the inverter bridge can be tapped.