Trans-Inductor Voltage Regulator Current Sensing for Transient PWM Control
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Solution Overview
Problem
Multiphase trans-inductor voltage regulators face challenges in accurately sensing and responding to transient conditions in output currents due to limitations in current sensing methods, leading to potential inaccuracies in pulse width modulation control.
Innovation Solution
A control circuit with an average current sense circuit and a correction circuit is implemented, using an average sensing capacitor and a correction capacitor to sense and correct the average current flowing through switching circuits, injecting information from the compensation inductor to improve the accuracy of pulse width modulation signals based on output voltage and transient conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate sensed current is used for each phase, then the measurement precision of individual phase currents is improved, but the device complexity increases due to requiring multiple sensing circuits
Solution Approach 1:
The patent combines multiple phase current sensing into a single average current sensing circuit that measures the total current through the compensation inductor. This merging approach reduces the number of sensing circuits from multiple individual phase sensors to one shared sensor, thereby reducing device complexity while still providing sufficient control information for the multiphase TLVR system
Solution Approach 2:
The single current sensing circuit serves multiple phases simultaneously by measuring the aggregate current. This universal sensing approach allows one sensing circuit to perform the function of multiple separate sensing circuits, reducing overall system complexity while maintaining adequate measurement capability for controlling all phases
2Device complexity
If an average sensed current is used for all phases, then the device complexity is reduced, but the measurement precision during transient conditions deteriorates
Solution Approach 1:
The compensation inductor serves as an intermediary element that captures the aggregate current information from all phases. By sensing the current through this compensation inductor, the system obtains an averaged current measurement that represents the total load demand, providing a simplified yet effective means of current sensing for multiphase control
Solution Approach 2:
The system implements current-mode control with feedback from the sensed average current. The controller uses this feedback signal to adjust the duty cycles of individual phases, ensuring that the aggregate output matches the desired current level. This feedback mechanism compensates for the averaging effect and maintains precise control despite using a single sensing circuit
3Productivity
If constant ON-time current-mode control is used, then the productivity is improved through faster transient response, but the measurement precision of output voltage deteriorates due to reduced sensing time
Solution Approach 1:
The system performs preliminary current sensing during the ON-time period before the voltage measurement phase. By capturing current information during the switching ON period, the system obtains sufficient control data without requiring extended measurement times, thus maintaining fast transient response while ensuring adequate measurement precision
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enhances the accuracy of current sensing and control during transient conditions, ensuring precise regulation of output voltage and current in multiphase power supplies, maintaining stability and responsiveness.
Implementation Method 1
The average current sense circuit comprises an average sensing capacitor with a first end coupled to the first current sense terminal and a second end coupled to the second current sense terminal
Implementation Method 2
The correction circuit is configured the be coupled to the compensation inductor. The correction circuit comprises a correction capacitor with a first end coupled to a first end of the compensation inductor and a second end coupled to the second current sense terminal
Implementation Method 3
Based on an output voltage of the multiphase power supply and a signal between the first current sense terminal and the second current sense terminal, the controller is configured to provide a plurality of pulse width modulation signals respectively at the plurality of switching control terminals to control a plurality of switching circuits
Data Source
AI summary
A multiphase power supply has an input terminal, an output terminal, a plurality of transformers, a plurality of switching circuits, and a control circuit. Secondary windings of the plurality of transformers are coupled in series with a compensation inductor. The plurality of switching circuits are coupled in parallel between the input terminal and the output terminal. Each of the plurality of switching circuits is coupled to the output terminal via a primary winding of a corresponding transformer. The control circuit senses an average current flowing through the plurality of switching circuits and a current flowing through the compensation inductor respectively, and corrects a sensing result of the average current based on the current flowing through the compensation inductor. The control circuit further provides a plurality of pulse width modulation signals based on the output voltage and the corrected sensing result to control the plurality of switching circuits.