Power Supply Voltage Detection for Energy Saving
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Solution Overview
Problem
Existing power supply apparatuses face challenges in precisely controlling the operation of control circuits in response to input AC voltage fluctuations, leading to increased power consumption and potential damage from excessive current due to inefficient voltage detection methods.
Innovation Solution
A power supply apparatus that includes a rectifying/smoothing circuit, a first converter, and a second converter, with a control circuit that uses separate voltage generation circuits to detect the operation start and stop thresholds, allowing precise control of the control circuit's operation and reducing power consumption by monitoring the median voltage of switching elements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage-dividing circuit is used to detect voltage at both ends of a switching element, then voltage detection is enabled, but power consumption increases even in energy-saving mode
Solution Approach 1:
The patent extracts the voltage detection function from the main power supply circuit by using the auxiliary winding of the transformer to generate a separate detection voltage. This allows the voltage detection circuit to operate independently with minimal power consumption, especially in energy-saving modes where the main converter is inactive.
Solution Approach 2:
The auxiliary winding of the transformer serves multiple functions: it provides isolation between primary and secondary sides, generates detection voltage for the control circuit, and enables voltage monitoring without requiring additional power-consuming detection circuits.
2Reliability
If the control IC is designed to stop operating when input AC voltage falls to operation stop voltage or lower, then element damage from excessive current is prevented, but the control IC may fail to start when operation start voltage becomes too high
Solution Approach 1:
The patent changes the reference parameter for voltage detection from a fixed voltage level to a voltage proportional to the auxiliary winding output. This allows the operation start and stop voltages to dynamically adapt to the actual input AC voltage conditions, ensuring reliable operation across varying input voltages.
Solution Approach 2:
The control circuit continuously monitors the voltage from the auxiliary winding and adjusts its operation based on feedback. This enables accurate detection of input voltage conditions and appropriate control of the switching elements to prevent overcurrent while maintaining reliable startup.
3Measurement precision
If the operation start voltage and operation stop voltage are set proportionally to input AC voltage, then voltage detection accuracy is improved, but voltage variations under different circumstances cause inconsistent control IC operation
Solution Approach 1:
The patent makes the detection voltage dynamic by deriving it from the auxiliary winding output, which automatically adjusts with input voltage variations. This dynamic approach maintains consistent detection accuracy across different input voltage conditions without requiring manual recalibration.
Solution Approach 2:
The patent uses an asymmetric voltage detection approach where the detection voltage is derived from the auxiliary winding rather than using a symmetric voltage-dividing circuit. This asymmetry allows the detection system to adapt to varying input conditions while maintaining stable and consistent operation.
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 enables precise start and stop control of the control circuit in response to input AC voltage changes, protecting elements from overcurrent and through-current, while reducing power consumption and maintaining conversion efficiency.
Implementation Method 1
A rectifying/smoothing circuit rectifies and smoothes an AC voltage that has been input, and outputs a rectified and smoothed voltage
Implementation Method 2
A rectifying/smoothing circuit rectifies and smoothes an AC voltage that has been input, and outputs a rectified and smoothed voltage
Implementation Method 3
A first converter converts the voltage output from the rectifying/smoothing circuit with a first transformer, and outputs a converted voltage
Implementation Method 4
A second converter converts the voltage output from the rectifying/smoothing circuit with a second transformer, and outputs a converted voltage
Data Source
AI summary
A power supply apparatus determines that an input AC voltage has reached a voltage at which a power supply control IC can start operating, based on the voltage at an auxiliary winding of a transformer included in a first converter. Note that since the first converter operates so as to maintain a constant voltage at the auxiliary winding, whether the input AC voltage has fallen to an operation lower limit voltage or lower cannot be detected by only monitoring the voltage at the auxiliary winding. The power supply apparatus monitors a second voltage that is proportional to the input AC voltage is generated from the voltage being applied to the primary side of a second converter. Accordingly, the power supply control IC starts and stops operating in accordance with the input AC voltage.