Switched Capacitor Converter Precharge Control for Current Spike Prevention
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Solution Overview
Problem
Existing switched capacitor converters (SCCs) face issues with uncontrollable voltages due to failures like short circuits, leading to large instantaneous currents that can damage circuit components.
Innovation Solution
A control circuit and method for SCCs that includes a switching signal generation circuit and an adjustment circuit to adjust the terminal voltages of the flying capacitor to match the output voltage before operation, using pull-down signals with controlled current values to prevent damage from large currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the switching transistors are directly turned on to connect the input voltage, then the SCC can perform voltage conversion, but large instantaneous current may flow through the switching transistors or flying capacitor that affects the working reliability
Solution Approach 1:
The patent applies preliminary action by detecting the terminal voltages of the flying capacitor before switching transistors are turned on, and pre-adjusting these voltages to match the output voltage through an adjustment circuit. This preliminary voltage matching prevents large instantaneous currents when the switching transistors are subsequently activated, thus maintaining both productivity and reliability.
Solution Approach 2:
The patent implements feedback by continuously detecting the terminal voltages of the flying capacitor and comparing them with the output voltage. Based on this feedback information, the control circuit adjusts the switching signals to pre-condition the flying capacitor voltages, ensuring they match the output voltage before main switching operations begin, thereby preventing harmful current spikes.
2Device complexity
If the SCC operates without voltage adjustment, then the circuit structure remains simple, but the terminal voltages of the flying capacitor may not match the output voltage causing component damage
Solution Approach 1:
The patent introduces an adjustment circuit as an intermediary between the flying capacitor and the main power conversion path. This intermediary circuit gently adjusts the flying capacitor terminal voltages to match the output voltage before main operations begin, preventing direct harmful connections while maintaining overall circuit simplicity through modular design.
Solution Approach 2:
The adjustment circuit performs preliminary voltage conditioning of the flying capacitor terminals before the main switching transistors are activated. By pre-matching the voltages, the system eliminates the risk of component damage without requiring complex real-time protection circuits, thus balancing simplicity and safety.
Data Source
AI summary
A control circuit and control method for a switched capacitor converter (SCC) are provided. An adjustment circuit makes adjustment with a small pull-down current, such that two terminal voltages of a flying capacitor are consistent with an output voltage. Before the SCC works formally for voltage conversion, the two terminal voltages of the flying capacitor are the same as the output voltage.