Power Converter Current Sensing With Capacitor Voltage Hold
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Solution Overview
Problem
Power converters face challenges in accurately sensing current and voltage due to lengthy settling times of sensing circuitry, especially when operating at high switching frequencies, leading to potential malfunctions and inaccurate control.
Innovation Solution
Implementing a control scheme that alternately enables and disables the feedback control loop of the sensing circuit, using switches to maintain the voltage across a capacitor during non-sensing periods, thereby reducing the settling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the feedback control loop is continuously enabled in the sensing circuit, then the sensing circuit can continuously monitor voltage and current, but the settling time becomes excessively long, leading to inaccurate sensing at high switching frequencies
Solution Approach 1:
The patent applies periodic action by enabling the feedback control loop only during specific sensing periods rather than continuously. The controller periodically activates the feedback loop to sense voltage and current, then disables it during non-sensing periods. This periodic operation allows the capacitor to be charged during sensing intervals and maintained during non-sensing intervals, achieving accurate measurements at high switching frequencies without excessive settling time.
Solution Approach 2:
The patent implements preliminary action by pre-charging the capacitor to the desired voltage level before the sensing period begins. The controller proactively activates the feedback control loop in advance to charge the capacitor, ensuring the capacitor is ready with the correct voltage before measurement is needed. This preliminary charging action eliminates delays and reduces settling time during actual sensing operations.
2Productivity
If the switching frequency is increased to improve power converter performance, then productivity increases, but the settling time of the sensing circuit becomes too long relative to the switching period, causing malfunction
Solution Approach 1:
The patent resolves this contradiction by implementing periodic sensing that synchronizes with the high switching frequency. The feedback control loop is activated in periodic bursts during specific phases of the switching cycle, allowing the capacitor to charge and discharge in sync with the high-frequency switching. This periodic operation enables reliable sensing even at high switching frequencies where continuous sensing would be impossible due to insufficient settling time.
Solution Approach 2:
The patent applies dynamics by making the feedback control loop dynamic rather than static. The controller dynamically switches the feedback loop on and off based on the switching phase, adapting the sensing operation to the high-frequency switching regime. This dynamic operation allows the system to maintain reliability at high productivity levels by adjusting the sensing timing to match the switching frequency.
3Use of energy by moving object
If the feedback control loop is disabled during non-sensing periods to reduce power consumption, then energy efficiency improves, but the voltage across the capacitor cannot be maintained, increasing settling time for the next sensing period
Solution Approach 1:
The patent applies partial action by maintaining the feedback control loop in a standby state during non-sensing periods rather than fully disabling it. The controller keeps the loop partially active with reduced power consumption, sufficient to maintain the capacitor voltage without requiring full operational power. This partial maintenance approach balances energy efficiency with the need to minimize settling time for the next sensing period.
Solution Approach 2:
The patent implements beforehand cushioning by proactively maintaining the capacitor voltage during non-sensing periods through low-power standby operation of the feedback control loop. This cushioning action ensures the capacitor is pre-prepared with the correct voltage level before the next sensing period begins, reducing the settling time required when sensing resumes while consuming minimal energy during the intermediate period.
Data Source
AI summary
An integrated circuit (IC) for controlling a power converter. The IC includes a controller that, in a first sensing period, enables a sensing circuit of the power converter and electrically connects an output node of an op amp of the sensing circuit and a first node of a capacitor of the sensing circuit, creating a first voltage across the capacitor; in a period between the first sensing period and a second sensing period, disables the sensing circuit and disconnects the output node of the op amp and the first node of the capacitor to maintain the first voltage across the capacitor; and in the second sensing period, enables the sensing circuit and connects the output node of the op amp and the first node of the capacitor, the maintained first voltage across the capacitor reducing a settling time for the enabled sensing circuit.