Multi-Phase PWM Controller for Balanced Current Limiting
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Solution Overview
Problem
Conventional current limit methods in multi-phase power conversion circuits struggle with current balance, leading to uneven output currents and potential failure of the current balancing mechanism due to phase-specific blocking, while phase shielding methods cause output instability upon reactivation.
Innovation Solution
A controller method that generates PWM signals based on current sensing and comparison with a default value, temporarily delaying trigger signals when the load current exceeds the threshold, using ramp and compensation signals to maintain balanced phase currents without altering the number of active phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If PWM skip mode is used to limit total output current, then current limit effect is achieved, but current balance between phases deteriorates
Solution Approach 1:
The patent segments the current limiting function by introducing separate current sensing circuits for each phase (first to fourth phases) and individual current limit control signals (first to fourth current limit control signals). This allows independent monitoring and control of each phase's current while maintaining overall current balance, resolving the contradiction between total current limiting and phase current balance.
2Power
If phase shielding is used to limit total output current, then current limit effect is achieved, but output stability deteriorates upon reactivation
Solution Approach 1:
The patent applies preliminary action by continuously monitoring phase currents through sensing circuits before current limit conditions occur. The current limit control signals are generated in advance based on predetermined thresholds, allowing smooth transition into and out of current limiting states without sudden reactivation instability, thus maintaining output stability while achieving current limiting.
Data Source
AI summary
A controller of a power conversion circuit generates PWM signals to control output stage circuits to provide an output voltage and a load current to an output terminal. The controller includes a sensing circuit, a comparison circuit, a PWM generation circuit and a control loop. The sensing circuit generates a current sensing signal related to load current. The comparison circuit compares the current sensing signal and a default value representing a current threshold to generate a comparison result. The control loop, coupled to the output terminal, the PWM generation circuit and the comparison circuit, generates a trigger signal according to a reference voltage and the output voltage to control the PWM generation circuit to generate PWM signals. When the comparison result indicates that the load current exceeds current threshold, the control loop temporarily stops providing trigger signal to PWM generation circuit to delay the generation of PWM signals.