Capacitive Power Supply Standby Loss Reduction via Segmented Paths
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Solution Overview
Problem
Capacitive power supply systems are inefficient in standby mode due to excessive power dissipation by components like zener diodes, surge resistors, and bleed resistors, which is not optimized for varying power consumption levels in household appliances.
Innovation Solution
A power supply system incorporating a DC-DC converter and a rectifying circuit with capacitive coupling, where the DC-DC converter takes over power delivery in operational mode and the rectifying circuit handles standby power, minimizing capacitance and reducing power dissipation by using a voltage limiter to manage output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a capacitive power supply with zener diode, surge resistor and bleed resistor is used to provide power in both standby and operational modes, then the power supply can deliver maximum power in operational mode, but excessive power is dissipated by these components in standby mode resulting in low efficiency
Solution Approach 1:
The power supply system is divided into two separate power delivery paths: a first power supply path including a rectifying circuit for standby mode operation, and a second power supply path including a DC-DC converter for operational mode operation. This segmentation allows each path to be optimized for its specific mode, preventing the excessive power dissipation that occurs when a single capacitive power supply must handle both modes.
Solution Approach 2:
The system dynamically switches between the first power supply path (rectifying circuit) during standby mode and the second power supply path (DC-DC converter) during operational mode. This dynamic reconfiguration allows the system to adapt its power delivery mechanism to the current operational state, minimizing energy losses in each mode.
2Loss of energy
If the capacitance of the capacitor is reduced to minimize power losses, then power dissipation decreases, but the maximum deliverable power also decreases because maximum power has a linear relation with capacitance
Solution Approach 1:
By segmenting the power supply into two paths, the system can use a smaller capacitor optimized for standby mode power requirements, while the DC-DC converter in the second path provides the additional power needed for operational mode without requiring a larger capacitor that would increase standby losses.
3Device complexity
If a single capacitive power supply is used for both standby and operational modes, then device complexity is reduced, but the efficiency in standby mode becomes too low due to unnecessary power dissipation
Solution Approach 1:
The power supply is segmented into two distinct paths with different levels of complexity: a simple rectifying circuit for standby mode and a DC-DC converter for operational mode. This segmentation increases device complexity slightly but dramatically improves efficiency by preventing unnecessary power dissipation in standby mode.
Solution Approach 2:
Different quality levels are applied to different parts of the system: the standby mode uses a simpler rectifying circuit with lower power handling capability, while the operational mode uses a more capable DC-DC converter. This local differentiation optimizes efficiency for each operational state.
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 enhances efficiency by reducing power dissipation in standby mode and allows for optimized power delivery in both operational and standby modes, minimizing losses and component costs.
Implementation Method 1
A capacitive power supply has a capacitor which provides a capacitive coupling to an AC mains voltage and acts as a charge-pump
Implementation Method 2
A rectifying circuit is used to obtain a DC voltage
Data Source
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AI summary
A power supply system (200) is provided which comprises a first input (206), an output (218), a DC-DC converter (204), a rectifying circuit (212) and a voltage limiter (214). An AC voltage is received by the first input. Power is supplied to a load (216) via the output. The DC-DC converter comprises a second input (203) which is capacitively coupled to the first input, and the DC-DC converter provides power to the output. The rectifying circuit is capacitively coupled to the first input and is arranged between the first input and the output. The rectifying circuit provides a rectified output voltage to the output. The voltage limiter is coupled to the output and limits the rectified voltage to a predefined voltage.