Bootstrap Supply for Switched Mode Power Converter Efficiency
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Solution Overview
Problem
Existing switched mode power converters face efficiency losses due to the need for a high-voltage supply to generate a control voltage, which increases cost and complexity, and often requires additional high-voltage transistors, making them costly and difficult to integrate.
Innovation Solution
A power converter controller that uses timing logic to selectively control switching elements, enabling energy storage during a bootstrap charging phase and isolating the load circuit to minimize power wastage, employing inductive and capacitive storage elements to efficiently generate a control voltage source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a dissipative series element is used to generate control voltage from high voltage supply, then control voltage is obtained, but power efficiency deteriorates due to significant power wastage
Solution Approach 1:
The patent changes the operating parameters by using a switching transistor to periodically connect and disconnect the high voltage supply, transforming the continuous dissipative operation into periodic pulsed operation. This allows the control capacitor to be charged efficiently during ON periods and maintains voltage during OFF periods, dramatically reducing average power loss while still providing stable control voltage.
Solution Approach 2:
The patent implements periodic switching action where the switching transistor operates in pulsed mode rather than continuous conduction. The transistor switches ON to charge the control capacitor from the high voltage supply, then switches OFF to allow the capacitor to discharge and maintain voltage. This periodic action reduces the duty cycle and average current draw, minimizing power wastage while ensuring reliable control voltage generation.
2Loss of energy
If an auxiliary switch mode power supply is used to generate control voltage, then power efficiency is improved, but device complexity increases due to additional windings and magnetic elements
Solution Approach 1:
The patent makes the existing switching transistor serve multiple functions: it controls the main power conversion operation and simultaneously generates the control voltage for the controller. The same transistor's switching action charges the control capacitor, eliminating the need for separate auxiliary power supply components. This multi-functionality approach maintains high efficiency while avoiding additional complexity.
Solution Approach 2:
The patent merges the control voltage generation function with the main power switching function. Instead of having separate auxiliary windings and magnetic elements for control power, the control capacitor is charged through the existing switching transistor and its associated circuitry. This consolidation combines multiple functions into existing components, reducing overall device complexity while maintaining efficiency.
3Loss of energy
If a high-voltage switching element is added to generate control voltage, then power efficiency is maintained, but manufacturing cost and integration difficulty increase
Solution Approach 1:
The patent enables the power converter system to generate its own control voltage using its existing components without requiring additional external parts or complex integration. The switching transistor and control capacitor form a self-sufficient bootstrap circuit that automatically charges and maintains control voltage using the system's own high voltage supply and switching action, eliminating the need for separately manufactured high-voltage control components.
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 approach enhances efficiency by reducing power wastage and cost, allowing for the use of lower voltage fabrication processes while maintaining responsive power conversion capabilities.
Implementation Method 1
The inductive storage element is coupled to a second power supply terminal to store energy in the inductive storage element during a load charging cycle of the power converter
Implementation Method 2
The capacitive storage element is coupled to the inductive storage element to transfer energy from the inductive storage element to the capacitive storage element during a bootstrap charging cycle of the power converter
Data Source
AI summary
A power converter controller is operable to control power provided to a load circuit coupled between a first voltage supply terminal and a first switching element by controlling the first switching element and to control power provided to an energy storage element coupled to the first switching element. The energy storage element is operable to provide a power supply. A first control terminal couples to a control input of the first switching element. A first load terminal couples to the first switching element and the charge storing element. A second switching element couples between the first load terminal and a second voltage supply terminal. Timing logic is operable to selectively provide a control signal at the first control terminal to control the first switching element and to selectively control the second switching element to supply power to the load circuit during a load powering phase by enabling the first and second switching elements, charge the energy storage element during a bootstrap charging phase by enabling the first switching element and disabling the second switching element, and allowing the load circuit to operate in isolation during a passive phase by disabling at least the first switching element.