Converter System Energy Feedback Control
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Solution Overview
Problem
Existing converter systems face challenges in preventing dangerously high intermediate-circuit voltage rises during energy feedback into alternating-voltage supply systems, leading to interference currents and unstable operation.
Innovation Solution
A converter system with a block-type energy feedback mechanism, incorporating a regenerative power rectifier, a DC/DC transformer, and a control unit that regulates current through a setpoint-value characteristic, ensuring smooth energy feedback by controlling voltage at zero crossings and phase voltage intersections, reducing oscillations and allowing for stable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If regenerative feedback is implemented to feed energy back into the AC-voltage supply system, then energy efficiency is improved, but intermediate-circuit voltage rises dangerously high
Solution Approach 1:
A DC/DC transformer is introduced as an intermediary component between the intermediate circuit and the regenerative power inverter. This transformer enables controlled energy feedback by transforming the DC voltage and regulating the current fed back into the AC supply system, thereby preventing dangerous voltage rises in the intermediate circuit while maintaining energy efficiency.
Solution Approach 2:
The control unit dynamically adjusts the setpoint-value characteristic for current feedback based on the instantaneous voltage level in the intermediate circuit. By changing the feedback current parameter in response to voltage conditions, the system prevents dangerous voltage rises while maximizing energy recovery. The setpoint characteristic is specifically designed to pass through zero at line voltage zero crossings to eliminate interference currents.
2Loss of energy
If energy feedback is increased to improve regenerative capability, then energy recovery is improved, but interference currents and oscillation tendency increase
Solution Approach 1:
The control unit continuously monitors the intermediate-circuit voltage and line voltage zero crossings, then adjusts the feedback current setpoint in real-time. This feedback mechanism ensures that energy recovery is optimized while interference currents are eliminated by forcing the setpoint characteristic to pass through zero at each line voltage zero crossing, creating a stable and system-compatible energy feedback process.
3Stability of the object's composition
If smooth setpoint-value characteristic is used to reduce oscillations, then system stability is improved, but control complexity increases
Solution Approach 1:
The control unit generates a periodic setpoint-value characteristic that synchronizes with the AC supply system frequency. The characteristic is designed to pass through zero at each line voltage zero crossing and follows a smooth sinusoidal-like pattern between crossings. This periodic control approach provides system stability by matching the grid frequency while avoiding the need for complex real-time calculations, as the setpoint waveform can be pre-calculated and synchronized.
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
The solution enables predefined and smoothly ramped energy feedback, reducing interference currents and achieving stable operating behavior, allowing for system-compatible energy feedback without the need for sinusoidal feedback, thus enhancing operational stability and compatibility.
Implementation Method 1
a DC/DC transformer (102) including a control unit (108)
Data Source
AI summary
A converter system and a method for operating a converter system having block-type energy feedback, in particular, includes: a power inverter that feeds energy back to an AC-voltage supply system, i.e. in particular a first power inverter; a DC/DC transformer having a control unit; and an electric motor, which is able to be fed by a second power inverter. The DC-voltage-side terminal of the second power inverter is connected to a first terminal of the DC/DC transformer 102, and a current-acquisition device for acquiring the current conveyed by the DC/DC transformer to the terminal of the regenerative power inverter on the DC-voltage side is connected to a control unit, e.g., such that the current values acquired by the current-acquisition device are supplied to the control unit. The control unit supplies to the DC/DC transformer control signals such that the voltage supplied by the DC/DC transformer to the regenerative power inverter, the acquired current is able to be controlled, in particular controls, to a setpoint-value characteristic.