SMPS Link Voltage Control for Standby Power Loss Reduction
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Solution Overview
Problem
Switch mode power supplies (SMPS) face limitations in reducing power loss during standby operation mode due to the proportional relationship between switching power loss and switching frequency, which restricts efficiency improvements by controlling switching frequency alone.
Innovation Solution
A power supply apparatus and method that control the on-time of a control switch based on the peak value of the AC line voltage, using a line voltage detector, on-time generator, and pulse generator to adjust the pulse signal for the control switch, thereby reducing the voltage magnitude across the switching transistor in standby mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If burst mode switching is used to reduce power consumption in standby operation mode, then power loss is reduced, but switching frequency control alone has a limit in reducing power loss further
Solution Approach 1:
The patent changes the voltage parameter in the switching transistor from a constant value to a dynamically adjustable value. By controlling the link voltage to be lower during standby operation and higher during normal operation, the patent reduces switching power loss (proportional to voltage squared) while maintaining adaptability across different operation modes. This parameter change enables continued efficiency improvement beyond what frequency control alone can achieve.
2Loss of energy
If switching frequency is controlled to reduce power loss, then power loss is reduced, but further reduction is limited due to the proportional relationship between switching power loss and switching frequency
Solution Approach 1:
The patent transitions from controlling only the frequency parameter to controlling both frequency and voltage parameters. By dynamically adjusting the link voltage magnitude based on operation mode (lower in standby, higher in normal operation), the patent overcomes the diminishing returns of frequency-only control and achieves more effective power loss reduction.
3Loss of energy
If the on-time of control switch is reduced to lower link voltage magnitude, then switching power loss is reduced, but control precision must be maintained
Solution Approach 1:
The patent employs feedback control through a control switch that adjusts the link voltage based on detected AC line voltage conditions. The system monitors the operating state and dynamically adjusts the on-time of the control switch to maintain optimal voltage levels, ensuring both power loss reduction and precise control. This closed-loop approach maintains control precision while achieving the desired voltage magnitude adjustment.
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 effectively reduces power loss in the switching transistor during standby operation, enhancing the efficiency of the power supply with minimal additional cost and power loss in normal operation mode.
Implementation Method 1
a rectifier for rectifying an AC line voltage to generate the link voltage
Implementation Method 2
a converter for converting the link voltage to a DC voltage
Implementation Method 3
a line voltage detector for detecting the AC line voltage
Implementation Method 4
an on-time generator for generating a control signal for controlling the control switch through a pulse signal when the converter operates at a standby operation mode, the pulse signal having an on-time determined based on a peak value of a detected AC line voltage
Data Source
AI summary
A power supply includes a rectifier for rectifying an AC line voltage to generate a link voltage, a link capacitor for charging the link voltage, a control switch for controlling charge of the link capacitor, a converter for converting the link voltage to a DC voltage, and a switch controller. When the converter operates in a standby operation mode, the switch controller controls on-off of the control switch through a pulse signal having an on-time determined based on a peak value of a detected AC line voltage.