Source-Controlled MOS Transistor for Vcc Generation and Free-Wheeling Detection
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Solution Overview
Problem
Driver circuits for Solid State Lighting (SSL) devices require external components to generate supply voltage, increasing costs and complexity.
Innovation Solution
A driver circuit configuration that uses a primary power converter with a source-controlled power switch and multi-stage power converters to generate supply voltage Vcc, incorporating a control circuit for switching state control and free-wheeling detection, reducing the need for external components by utilizing parasitic capacitances and additional charging capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external components are used to generate supply voltage Vcc, then the supply voltage can be generated reliably, but the component count and cost increase
Solution Approach 1:
The power converter circuit generates its own supply voltage Vcc using its internal power switch and inductor, eliminating the need for external voltage generation components. The circuit serves itself by utilizing its existing components for dual purposes: power conversion and voltage generation
Solution Approach 2:
The power switch serves multiple functions: it acts as the main switching element for power conversion, a current source for voltage generation, and enables free-wheeling detection through its parasitic capacitance. This multi-functionality reduces the need for separate dedicated components
2Device complexity
If a source-controlled power switch is used for voltage generation and free-wheeling detection, then component count is reduced, but the detection of voltage changes becomes more challenging
Solution Approach 1:
An additional charging capacitor is introduced as an intermediary element to enhance the voltage change signal. This capacitor works together with the parasitic capacitance of the power switch to create a more detectable voltage oscillation at the control port, making free-wheeling detection easier despite the reduced component count
Solution Approach 2:
The patent utilizes changes in voltage parameters at the control port of the power switch to detect free-wheeling. By monitoring voltage oscillations and changes greater than a predetermined threshold, the system detects free-wheeling conditions without requiring additional detection 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
The solution allows for cost-efficient generation of supply voltage Vcc within the driver circuit, enhancing reliability and reducing component count while enabling effective free-wheeling detection and voltage regulation.
Implementation Method 1
The drain to source capacitance of the power switch may be used to enable a measurement of free-wheeling of the inductor at a reduced voltage level
Implementation Method 2
The generation of the supply voltage may be enhanced using an additional charging capacitor
Data Source
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Figure 2b
AI summary
The present document relates to power converters. In particular, the present document relates to free-wheeling detection and/or to the provisioning of the supply voltage of a driver circuit using a switched-mode power converter. A control circuit configured to control a switching state of a power switch (106) is described. A first port (121) of the power switch (106) is coupled to an inductor (103). The control circuit is configured to be coupled to a control port (120, 620) of the power switch (106); wherein the control port (120, 620) of the power switch (106) is different from the first port (121) of the power switch (106). The control circuit comprises a control unit (107, 601, 602) configured to generate a control signal for controlling the switching state of the power switch (106); wherein the control signal is to be provided to the control port (120, 620) of the power switch (106). Furthermore, the control circuit comprises free-wheeling sensing means (603) configured to detect an oscillation of a voltage at a measurement port (120, 620) of the power switch (106); wherein the measurement port (120, 620) of the power switch (106) is different from the first port (121) of the power switch (106); and wherein the oscillation of the voltage at the measurement port (120, 620) is indicative of free-wheeling of the inductor (103).