Multi-Phase Power Converter Current Balance with Constant On-Time Control
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Solution Overview
Problem
Multi-phase power converters with constant on-time control face challenges in achieving current balance due to mismatched impedances between channels, leading to imbalanced currents despite balanced voltages.
Innovation Solution
A current balance mechanism is implemented in multi-phase power converters with constant on-time control, where each channel's current is compared to a target value to generate an error signal, and the on-time of the control signal is modulated based on this error to balance currents across channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If constant on-time control is used in multi-phase power converters, then switching frequency varies and response speed improves, but current balance between channels deteriorates due to mismatched impedances
Solution Approach 1:
The patent implements a feedback mechanism where the actual channel currents are sensed and compared against target current values. The current errors are fed back to the on-time generator, which dynamically adjusts the on-time of each channel to compensate for impedance mismatches. This closed-loop feedback ensures current balance is maintained even when operating in constant on-time mode with varying switching frequencies.
Solution Approach 2:
The patent dynamically changes the on-time parameter for each channel based on detected current imbalances. By adjusting the on-time duration according to current error signals, the system compensates for impedance variations between channels. This parameter adjustment allows the system to maintain current balance while operating with variable switching frequencies characteristic of constant on-time control.
2Reliability
If current balance mechanism is added to multi-phase power converter, then current balance improves, but device complexity increases
Solution Approach 1:
The patent integrates the current balance function into the existing control architecture by making the on-time generator perform dual functions: determining on-time based on constant on-time control requirements and simultaneously generating current balance compensation signals. This multi-functionality approach allows current balance to be achieved without adding completely separate control circuits, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent merges the current sensing, error detection, and on-time adjustment functions into a unified control mechanism. The current error signal generation and on-time determination are combined in the on-time generator circuit, which processes both the constant on-time control signals and the current balance feedback signals together. This merging reduces the number of separate components and simplifies the overall control circuit architecture.
Data Source
AI summary
A multi-phase power converter with constant on-time control includes a plurality of channels to convert an input voltage into an output voltage, and each of the channels is driven by a control signal. When all channel currents of the channels are balanced, each of the control signals remains a constant on-time. When the channel currents are imbalanced, the on-times of the control signals are modulated according to the difference between each channel current and a target value for current balance between the channels.