Converter Circuit Rectifier Switching Loss Reduction
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Solution Overview
Problem
Converter circuits experience switching losses and system impedance losses when no or almost no real power is output to an electrical load, which cannot be tolerated.
Innovation Solution
The method involves continuously monitoring the voltage across the capacitive energy storage circuit and the real and reactive power on the AC voltage-side of the inverter unit, and blocking the rectifier switch signal if the voltage is within a predefinable range and the real power is below a set value, thereby disconnecting the controllable power semiconductor switches in the rectifier unit to prevent switching actions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rectifier switch signal is continuously generated to maintain voltage on the capacitive energy storage circuit, then the voltage stability is improved, but switching losses and system impedance losses increase
Solution Approach 1:
The rectifier switch signal is generated periodically only when necessary (when voltage drops below the lower limit or real power exceeds the threshold), rather than continuously. This periodic switching maintains voltage stability within the predefined range while eliminating unnecessary switching losses during no-load or light-load conditions.
Solution Approach 2:
The control method dynamically changes the switching parameters of the rectifier based on the operating conditions. When the converter is supplying real power, normal switching is applied. When real power drops below a threshold, the switching is reduced or stopped, changing the operational parameters to minimize losses while maintaining voltage within acceptable limits.
2Adaptability or versatility
If the controllable power semiconductor switches remain connected to maintain reactive power supply, then the reactive power support is improved, but switching losses and system impedance losses increase
Solution Approach 1:
The control strategy segments the operational modes: when real power is below the threshold, the rectifier switching is disconnected to eliminate losses, while the inverter continues to independently provide reactive power support. This segmentation allows reactive power functionality to be maintained without the penalty of rectifier switching losses.
3Measurement precision
If the rectifier unit operates continuously to maintain DC voltage, then the voltage regulation is improved, but productivity decreases due to unnecessary switching actions
Solution Approach 1:
The capacitive energy storage circuit serves itself by maintaining voltage within the predefined range through its natural discharge characteristics when the rectifier is disconnected. The system uses the existing energy storage capacity to bridge periods when rectifier switching is minimized, eliminating unnecessary switching actions while maintaining adequate voltage regulation.
Data Source
AI summary
A method is disclosed for operating a converter circuit, in which controllable power semiconductor switches of the rectifier unit of a converter circuit are controlled by a rectifier switch signal and the controllable power semiconductor switches of the inverter unit of the converter circuit are controlled by an inverter switch signal. In order to reduce losses in the no-load state of the converter circuit, the rectifier switch signal is blocked in order to disconnect the controllable power semiconductor switches of the rectifier unit if defined conditions of the converter circuit are fulfilled.