Power Supply Circuit Burst Mode for Controller Voltage Stability
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Solution Overview
Problem
Modern AC/DC power supplies, such as those following USB-PD specifications, face challenges in maintaining a stable power supply to the primary side controller during low or no load conditions, leading to system shutdown due to voltage drops below a threshold, especially during negative voltage transitions, which conventional solutions like bleeder elements or increased capacitor capacity are costly and inefficient.
Innovation Solution
Implementing a controlled burst mode operation that allows for low-energy bursts to maintain the primary side supply voltage without significantly impacting the output voltage, using a combination of energy storage and transfer phases in the auxiliary winding, and employing threshold-based control to manage bursts independently of output voltage ramps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional solutions like bleeder elements or increased capacitor capacity are used, then the primary side supply voltage stability is improved, but the cost and efficiency deteriorate
Solution Approach 1:
The patent changes the operational parameters of the power supply circuit by implementing controlled burst mode operation. Instead of using passive components like bleeder elements or larger capacitors, the system dynamically adjusts the switching behavior to maintain voltage stability during transitions, thereby avoiding additional hardware costs while improving reliability
Solution Approach 2:
The patent employs periodic burst mode operation where the power supply circuit switches between active and standby states in controlled bursts. This periodic action allows the circuit to maintain adequate voltage levels during transitions without requiring continuous power consumption or additional energy-storing components, thus reducing cost while maintaining stability
2Reliability
If conventional solutions like bleeder elements or increased capacitor capacity are used, then the primary side supply voltage stability is improved, but the efficiency deteriorates
Solution Approach 1:
The patent modifies the operational parameters by implementing controlled burst mode that adjusts switching frequency and duration based on load conditions. This dynamic parameter adjustment maintains voltage stability during transitions without the continuous energy dissipation associated with bleeder elements or the excessive capacitance charging/discharging cycles
Solution Approach 2:
The controlled burst mode operates periodically, activating the switching circuit only when necessary to maintain voltage levels. This periodic operation significantly reduces energy loss compared to continuous operation required by conventional solutions, as the circuit remains in a low-power state during non-critical periods
3Ease of manufacture
If burst mode operation is implemented, then the cost and efficiency are improved, but the risk of system shutdown due to voltage drops increases
Solution Approach 1:
The patent incorporates feedback control mechanisms that monitor the primary side supply voltage and adjust the burst mode operation accordingly. When voltage levels approach critical thresholds, the controller modifies burst frequency and duration to prevent shutdown, ensuring system reliability while maintaining cost-effectiveness
Solution Approach 2:
The controlled burst mode implementation includes preliminary action by anticipating voltage drops during transitions and proactively initiating burst operation before critical voltage levels are reached. This predictive approach prevents system shutdown while avoiding the need for expensive protective components
4Loss of time
If controlled burst mode operation is used, then the transition times are reduced, but the complexity of control increases
Solution Approach 1:
The patent implements dynamic control where the burst mode parameters (frequency, duration, amplitude) are adjusted in real-time based on operating conditions. This dynamic adaptation enables fast transition times by optimizing switching behavior for each specific scenario, while the control complexity is managed through standardized control algorithms
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 maintains the primary side circuitry active with minimal impact on output voltage, reduces transition times, and avoids system shutdown, while being computationally simple and cost-effective by limiting energy bursts to charge only the primary side supply voltage.
Implementation Method 1
Power can be supplied to a primary side controller (an integrated circuit or IC, for instance) by an auxiliary winding on the primary side of a transformer in the controller. When the system is switching, a small part of the converter power flows through the auxiliary winding and provides a supply for the IC.
Data Source
AI summary
An embodiment provides a circuit including a transformer having a primary winding coupled to an input port configured to receive an input voltage and a secondary winding configured to provide an output voltage at an output port, controller circuitry configured to switch on and off a current through the primary winding so that energy is transferred to the secondary winding while switching and supply circuitry connected to the controller circuitry, wherein the supply circuitry is coupled to an auxiliary winding of the transformer and configured to provide a supply voltage for the controller circuitry. The controller circuitry is further configured to: transition to a burst mode to switch on and off the current through the primary winding in first bursts, wherein the first bursts are separated by intervals during which switching on and off the current through the primary winding of the transformer by the first bursts is discontinued and provide second bursts during the intervals in order to keep the supply voltage of the controller circuitry between a lower bound value and an upper bound value while the output voltage ramps down to a requested valley value or provide second bursts during the intervals after reaching a timeout limit in order to provide the supply voltage to the controller circuitry while the output voltage ramps down to a requested valley value.