Power Supply Input Drop Detection Across AC and DC
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Solution Overview
Problem
Conventional power-supply devices using switching power supply circuits with power factor improvement struggle to detect input voltage drops consistently between alternating-current (AC) and direct-current (DC) inputs, leading to different operating points and inefficient loss management.
Innovation Solution
A power-supply device is designed with a bridge rectification circuit, a voltage-dividing circuit, an attenuation circuit, and a voltage drop detection circuit. This configuration ensures that the same detection voltage is used for both AC and DC input voltage drops by attenuating the midpoint voltage to a predetermined ratio for both input types.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a power outage detection circuit is installed to detect input voltage drops, then the switching power supply circuit can be stopped to reduce losses, but the detection voltage differs between AC and DC inputs leading to inconsistent operation
Solution Approach 1:
The attenuation circuit is designed to process both AC and DC input voltages through the same detection path, creating a universal detection mechanism. The circuit uses identical attenuation ratios for both input types, ensuring that the detection voltage remains consistent regardless of whether the input is AC or DC, thereby resolving the inconsistency in detection operation
Solution Approach 2:
The invention changes the detection parameter from peak voltage (for AC) to a standardized attenuated voltage that accounts for both AC and DC inputs. By adjusting the attenuation ratio to match the relationship between peak and effective values, the detection circuit operates consistently for both input types at the same effective voltage level
2Ease of operation
If the switching power supply circuit operates with power factor improvement, then the input current waveform matches the input voltage, but input voltage drops cause increased input current and higher switching transistor losses
Solution Approach 1:
The detection circuit provides feedback about the input voltage level to the control circuit, which then adjusts the switching power supply circuit operation accordingly. When a voltage drop is detected, the control circuit stops or reduces switching operations, preventing the increase in input current and subsequent rise in switching transistor losses that would otherwise occur during power factor improvement 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
The solution allows for consistent detection of input voltage drops across AC and DC inputs, reducing switching transistor losses and improving the overall efficiency of the power-supply device.
Implementation Method 1
a bridge rectification circuit, in which an alternating-current input terminal is connected to the input terminals and in which a direct-current output terminal is connected to an input terminal of a load circuit
Implementation Method 2
a voltage-dividing circuit that is connected to the input terminals and that outputs a midpoint voltage of the input voltage
Implementation Method 3
an attenuation circuit that outputs a direct-current output voltage obtained by attenuating, to a predetermined ratio, a waveform of the midpoint voltage when the direct-current input voltage is applied, and that outputs an alternating-current output voltage obtained by attenuating, to a waveform having a peak voltage substantially equal to the direct-current output voltage, the midpoint voltage when the alternating-current input voltage is applied
Data Source
AI summary
A power-supply device includes a pair of input terminals, a bridge rectification circuit, a voltage-dividing circuit, an attenuation circuit, and a voltage drop detection circuit. The input terminals are applied with a direct-current input voltage and with an alternating-current input voltage which has the effective value substantially equal to the direct-current input voltage. In the bridge rectification circuit, the alternating-current input terminal is connected to the input terminals and in which the direct-current output terminal is connected to the input terminal of a load circuit. The voltage-dividing circuit is connected to the input terminals and outputs the midpoint voltage of the input voltage. The attenuation circuit outputs a direct-current output voltage obtained by attenuating, to a predetermined ratio, the waveform of the midpoint voltage of the voltage-dividing circuit when the direct-current input voltage is applied to the input terminal, and outputs an alternating-current output voltage obtained by attenuating, to a waveform having the peak voltage substantially equal to the direct-current output voltage, the midpoint voltage of the voltage-dividing circuit when the alternating-current input voltage is applied to the input terminal. The voltage drop detection circuit detects a drop in either the direct-current output voltage or the alternating-voltage output voltage, and accordingly detects a drop in the voltage that is input to the input terminal.