Cycloconverter Inductance Circulating Current Control
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Solution Overview
Problem
Cycloconverters face issues with unwanted circulating currents and complex control algorithms due to the lack of continuous current adjustment and high energy storage requirements, leading to inefficiencies and increased costs.
Innovation Solution
Incorporating inductances into the switching cells of cycloconverters to allow for continuous current flow and active current setting, with control signals formed from reference voltages and intermediate current setpoints to regulate circulating currents and optimize energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If no inductances are used in the switching cells, then the device complexity is reduced, but continuous current adjustment is not possible leading to high circulating currents
Solution Approach 1:
Inductances are introduced as intermediary elements in the switching cells to enable continuous current adjustment. These inductances act as mediators between the switching operations and the current flow, allowing for smooth current transitions and active current setting without requiring complex control algorithms or large energy storage capacitors.
Solution Approach 2:
The invention changes the electrical parameters of the switching cells by adding inductances, which fundamentally alters the current characteristics from discontinuous to continuous. This parameter change enables active current adjustment and reduces circulating currents without increasing overall device complexity significantly.
2Power
If large capacitances are used in switching cells to enable large energy transmission, then the energy transmission capability is improved, but the space requirement and cost increase enormously
Solution Approach 1:
Inductances serve as intermediary energy storage elements that replace the need for large capacitances. By using inductive energy storage combined with continuous current control, the system can transmit large amounts of electrical energy without requiring enormous capacitor banks, thus reducing space requirements and costs.
Solution Approach 2:
The invention substitutes capacitive energy storage with inductive energy storage and control mechanisms. This substitution allows for dynamic energy management through active current control rather than relying on passive large-capacitance energy storage, significantly reducing the physical space and cost requirements.
3Ease of operation
If full currents are switched on and off at output phase connections, then the control algorithm complexity increases, but the switching operation is simplified
Solution Approach 1:
The inductances enable continuous current flow through the switching cells, eliminating the need for abrupt current switching on and off. This continuity allows for smoother transitions and reduces the complexity of control algorithms required to manage the switching operations at output phase connections.
Solution Approach 2:
The invention introduces dynamic current control capabilities through the inductances, allowing the current to be continuously adjusted rather than simply switched on and off. This dynamic control reduces the complexity of switching operations while maintaining precise current management.
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 approach reduces unwanted circulating currents, enables continuous current flow, and allows for efficient energy exchange between branches, resulting in reduced component losses and lower space and cost requirements for cycloconverters.
Implementation Method 1
At least one inductance (6) is switched on in each serial connection, in each case a switching cell (2) with an inductance (6) forming a phase component (1)
Implementation Method 2
Each switching cell (2) has controllable bidirectional power semiconductor switches with a controlled unidirectional current-carrying direction and a capacitive energy store
Data Source
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AI summary
The invention relates to a method for operating an inverter circuit wherein the inverter circuit has n input phase connections (U1, V1, W1) and p output phase connections (U2, V2, W2), wherein n = 2 and p = 2, (n p) comprises two-pole switching cells (2) for switching at least one positive and at least one negative voltage between the poles, wherein each output phase connection (U2, V2, W2) is serially connected to each input phase connection (U1, V1, W1) via one switching cell (2) each, and each switching cell (2) has actuatable, bi-directional power semiconductor switches having a controlled, uni-directional current conducting direction and a capacitive energy store, wherein the semiconductor power switch of the switching cells (2) are actuated by means of an actuation signal (S1). In order to reduce undesired circulating currents and to compensate the mean voltage deviation of the capacitive energy store of all switching cells (2) to zero, according to the invention at least one inductor (6) is interpolated in each serial connection, wherein one switching cell (2) having an inductor (6) forms a phase component (1) and the actuation signal (S1) is formed for each phase component (1) from a reference signal (Vref, U1) relative to the voltage (U1) via the phase component (1) and from a voltage signal (VL) via the inductor (6) and the voltage signal (VL) is formed via the inductor (6) from a current intermediate target value (?iU1) of the current (iU1) by means of the phase component (1). The invention further relates to devices for carrying out said method.