Single-Inductor Dual-Control Loop Converter Freewheeling Current Shunt
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Solution Overview
Problem
Single-loop synchronous regulated switching converters experience reduced overall power efficiency due to energy losses during switching cycles, particularly pronounced at lighter load currents, which affects their performance in portable applications.
Innovation Solution
A single-inductor dual-control loop power converter is introduced, featuring an energy storage loop and a first switching power regulating loop, along with a second power-efficiency maximizing loop that shunts electrical current to minimize losses, using a PWM control loop and a real-time control loop to adjust the conductance of a power shunt transistor based on sensed freewheeling current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If synchronous driving of power output transistor and power shunt transistor is implemented, then power conversion capability is improved, but energy loss increases due to dead time and switching losses
Solution Approach 1:
The patent implements dynamic control of the power shunt transistor conductance based on real-time sensing of freewheeling current. The conductance is adjusted continuously to match the actual current conditions, allowing the system to optimize between power conversion capability and energy loss dynamically rather than using fixed synchronous driving
Solution Approach 2:
The patent changes the operating parameters by adjusting the power shunt transistor conductance based on sensed freewheeling current levels. At lighter load currents, the conductance is increased to reduce energy loss, while at heavier loads it is optimized for power conversion capability, thus resolving the contradiction through parameter adaptation
2Reliability
If dead time is provided to prevent shoot-through, then transistor safety is improved, but energy loss increases due to current flowing through parasitic diode
Solution Approach 1:
The patent extracts and separately controls the power shunt transistor function from the synchronous driving scheme. By independently controlling the power shunt transistor based on freewheeling current sensing, the system eliminates the need for dead time while maintaining transistor safety, as the power shunt transistor is only activated when freewheeling current is present
Solution Approach 2:
The patent implements feedback control by sensing the freewheeling current and using this information to dynamically adjust the power shunt transistor conductance. This feedback mechanism ensures transistor safety without requiring fixed dead time, as the control is continuously adapted to actual operating conditions
3Loss of energy
If power shunt transistor conductance is increased to reduce energy loss, then power efficiency is improved, but system complexity increases due to additional control loop
Solution Approach 1:
The patent makes the power shunt transistor serve multiple functions: it acts as a synchronous rectifier during normal operation and as an active loss-reduction element when freewheeling current is present. This multi-functionality allows the same component to address both power conversion and energy loss reduction without adding separate circuitry
Solution Approach 2:
The patent implements self-service control where the power shunt transistor's conductance is automatically adjusted based on sensed freewheeling current conditions. The system serves itself by using the current sensing information to directly control the transistor conductance, eliminating the need for complex external control circuits
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 configuration significantly enhances overall power efficiency across various load levels, eliminating the need for dead time and reducing energy losses, thereby improving performance compared to traditional single-loop converters.
Implementation Method 1
As the power inductor 6 stores electrical energy with its coil current
Implementation Method 2
the passive power diode 8 free-wheels the inductor current whenever the power output transistor 9 is turned off
Implementation Method 3
a second power-efficiency maximizing loop in parallel connection with the power diode for shunting a portion of its electrical current thus associated power loss
Data Source
AI summary
A high efficiency single-inductor dual-control loop power converter (SIDL) is proposed for converting unregulated DC input into regulated DC output to a power load. The SIDL includes:an energy storage loop having: a power inductor, a power capacitor and a power diode.A PWM switching power regulating loop for converting the unregulated DC input into the regulated DC output.a power-efficiency maximizing loop in parallel connection with the power diode.The power-efficiency maximizing loop includes: a power shunt transistor in parallel connection with the power diode and a real-time control loop adjusting, in response to a freewheeling current through the power diode, conductance of the power shunt transistor in a manner that a higher freewheeling current results in a higher conductance of the power shunt transistor.