AC-DC Converter DC Link Voltage Suppression Control
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Solution Overview
Problem
Existing power conversion apparatuses face challenges in rapidly responding to AC power source voltage variations due to the need to detect peak AC voltage, which can lead to communication delays and reliability issues when used in systems with separate AC-DC and DC-DC converters.
Innovation Solution
A power conversion apparatus that includes an AC-DC conversion circuit, a DC-DC conversion circuit, a smoothing capacitor, and a control unit that detects the DC link voltage to suppress output power if it falls below a predetermined value, allowing for rapid response to voltage variations without direct measurement of AC voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the command value of output current is determined based on input voltage detection, then malfunctioning is prevented, but response time increases due to the need to detect peak AC voltage
Solution Approach 1:
The patent introduces a DC link voltage detector as an intermediary element that measures the DC link voltage, which already reflects the AC input voltage variations after rectification. This mediator provides immediate voltage information without requiring peak detection of the AC waveform, thus maintaining reliability while reducing response time to half-period delays
Solution Approach 2:
The DC link voltage continuously reflects the AC input voltage status in advance through the rectification process. By monitoring this pre-processed voltage signal, the system can determine when to suppress output current before AC voltage drops occur, eliminating the need to wait for peak detection and reducing the half-period response delay
2Adaptability or versatility
If communication devices are added between AC-DC converter and DC-DC converter, then system functionality is enhanced, but responsiveness degrades due to communication delay
Solution Approach 1:
The patent merges the control functions by having the DC-DC converter directly monitor the DC link voltage (which reflects AC input status) and autonomously suppress its output current when voltage drops are detected. This eliminates the need for communication between separate converter units, removing communication delays while maintaining coordinated control functionality
Solution Approach 2:
The DC-DC converter performs self-service by autonomously detecting DC link voltage drops and independently suppressing its own output current without requiring external commands from the AC-DC converter. This self-contained control mechanism eliminates communication overhead and improves responsiveness
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 configuration enables faster response to AC power source voltage changes, enhances system responsiveness, and prevents excessive DC link voltage drops, improving the robustness and efficiency of power conversion.
Implementation Method 1
a smoothing capacitor parallel connected to the output end of the AC-DC conversion circuit
Data Source
AI summary
A power conversion apparatus for converting AC power supplied from an AC power source to DC power includes an AC-DC conversion circuit connected with the AC power source at an input end thereof for converting the AC power to DC power, a DC-DC conversion circuit connected with an output end of the AC-DC conversion circuit at an input end thereof for converting DC voltage level of the DC power generated by the AC-DC conversion circuit, a smoothing capacitor parallel connected to the output end of the AC-DC conversion circuit and the input end of the DC-DC conversion circuit, a DC link voltage detector for detecting a voltage of the smoothing capacitor as a DC link voltage, and a control unit for controlling operation of the DC-DC conversion circuit. The control unit suppresses an output power of the DC-DC conversion circuit, if the DC link voltage is smaller than a predetermined value.