Variable Reference Voltage for DC/DC Converter Inductor Current Control
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Solution Overview
Problem
Existing DC/DC converters face poor voltage regulation accuracy due to peak-to-average errors in inductor current mode, which are influenced by inductance values, leading to inconsistent output voltages across different loads.
Innovation Solution
An average inductor current mode voltage control method using a variable reference voltage generation unit, where the reference voltage is adjusted based on the valley inductor current, independent of inductance, allowing dynamic control of the constant off-time DC/DC converter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If peak current mode control is used, then the control is simple, but the voltage regulation accuracy deteriorates due to peak-to-average error
Solution Approach 1:
The patent changes the control parameter from peak current to average inductor current. By using average current mode control with a variable reference voltage that tracks the valley current, the system eliminates peak-to-average error while maintaining control simplicity. The reference voltage dynamically adjusts to compensate for inductance variations, improving voltage regulation accuracy without significantly increasing control complexity.
2Volume of moving object
If smaller inductance is used, then the converter size is reduced, but the peak-to-average error increases leading to poor regulation accuracy
Solution Approach 1:
The patent introduces dynamic adjustment of the reference voltage based on valley current detection. The variable reference voltage dynamically tracks the valley inductor current, allowing the control system to adapt to different inductance values. This dynamic compensation mechanism enables the use of smaller inductors while maintaining accurate voltage regulation, as the system automatically adjusts to compensate for the increased peak-to-average error inherent in smaller inductors.
3Adaptability or versatility
If inductance value is varied for different loads, then the converter can be optimized for different conditions, but the regulation accuracy deteriorates due to peak-to-average error variation
Solution Approach 1:
The patent implements feedback control using valley current detection. The valley inductor current is detected and used to generate a variable reference voltage that feeds back to the control circuit. This feedback mechanism allows the system to maintain accurate voltage regulation across different load conditions and inductance values, as the reference voltage automatically adjusts to compensate for changes in the current waveform characteristics.
Data Source
AI summary
A variable reference voltage generation unit used in DC/DC converter includes a sample-hold valley inductor current unit electrically connected to a reference voltage generation unit. The sample-hold valley inductor current unit receives the valley inductor current and converts it into the valley voltage. The reference voltage generation unit receives and converts a current signal two times of a designated current into a voltage signal two times of a designated voltage. The voltage signal two times of reference voltage is then subtracted by the valley voltage to produce the new reference voltage to compare with an inductor voltage for controlling the switching of a switching transistor of the DC/DC convertor.