Power Converter Startup Circuitry Eliminating Bleeder Resistor Loss
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Solution Overview
Problem
Existing power converter designs suffer from inefficiency due to continuous power loss caused by high value bleeder resistors during standby or normal operation, and increased bill of materials (BOM) part count due to the use of multiple discrete resistors.
Innovation Solution
The implementation of a startup circuitry that uses an existing voltage divider circuit to charge a bias capacitor without an external bias source or high value bleeder resistor, diverting current flow to provide energy to the power converter's controller during startup, thereby eliminating the need for continuous current flow through bleeder resistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high value bleeder resistor is used to charge the bias capacitor during startup, then the controller can begin operation, but continuous power loss occurs during standby or normal operation
Solution Approach 1:
The circuit performs preliminary charging of the bias capacitor through the divider circuit during startup before normal operation begins. The switch then disconnects the divider circuit from charging the capacitor, eliminating continuous power loss while maintaining the ability to provide initial bias power.
Solution Approach 2:
The switch dynamically changes the circuit configuration based on operational state - during startup it allows current flow through the divider circuit to charge the bias capacitor, and during normal operation it disconnects the divider circuit to eliminate continuous power consumption.
2Reliability
If multiple discrete resistors are used to implement the bleeder resistor for safety regulations, then safety requirements are met, but the bill of materials part count increases
Solution Approach 1:
The divider circuit resistors are combined with the existing feedback or AC sense resistor networks. This merging allows the same resistors to serve dual purposes - providing the necessary high impedance for safety compliance while also charging the bias capacitor during startup, thereby reducing the total part count.
Solution Approach 2:
The divider circuit resistors perform multiple functions: they provide the high impedance path required for safety compliance, charge the bias capacitor during startup, and maintain their original feedback or sensing functions. This multi-functionality eliminates the need for separate discrete resistors.
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 efficiency by reducing power consumption during standby operation and lowers the BOM part count, while providing additional protection against overvoltage and maintaining the same operating voltage range without penalties.
Implementation Method 1
a bias capacitor operable to be charged for providing energy to a controller
Implementation Method 2
A switch, coupled to the divider circuit, is operable to be turned on and off to divert current flow in the divider circuit for charging the bias capacitor
Data Source
AI summary
In one embodiment, circuitry is provided for startup of a power converter. The circuitry includes a bias capacitor operable to be charged for providing energy to a controller of the power converter. A divider circuit is coupled to a voltage source. Current flows through the divider circuit. A switch, coupled to the divider circuit, is operable to be turned on and off to divert current flow in the divider circuit for charging the bias capacitor. This provides energy to the controller of the power converter at startup without employing an external bias source or high value bleeder resistor.