Dynamic Inrush Current Limiter Control for Power Supply Efficiency
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Solution Overview
Problem
Existing inrush current prevention circuits in AC/DC power supplies consume excessive power during low output modes, such as sleep mode, due to the continuous operation of switches like relays, which increases power loss and heat generation, and are inefficient in quickly transitioning from low power to high power modes in image forming apparatuses.
Innovation Solution
A power supply apparatus with a controller that dynamically enables or disables an inrush current limiter based on output power levels, using a current detection circuit to determine when to turn the relay on or off, thereby reducing power loss by minimizing the time the inrush current prevention resistor is engaged during low output conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inrush current prevention circuit (resistor and switch) is continuously operated to prevent inrush current, then component protection is improved, but power consumption increases during low output modes
Solution Approach 1:
The patent applies dynamics by making the switch state changeable based on operating conditions. The switch is dynamically controlled to be in the closed state during high output modes (to short-circuit the inrush current prevention resistor and reduce power loss) and in the open state during low output modes (to maintain inrush current protection). This dynamic switching resolves the contradiction between continuous protection and power consumption.
2Loss of energy
If the switch is kept closed to reduce power loss, then power efficiency is improved, but inrush current protection is weakened
Solution Approach 1:
The patent uses dynamic control of the switch based on the output mode. During low output modes, the switch remains open to maintain inrush current protection while accepting some power loss. During high output modes, the switch closes to eliminate power loss through the inrush current prevention resistor. This dynamic adaptation resolves the contradiction between power efficiency and protection reliability.
3Reliability
If the inrush current prevention resistor is always engaged, then component safety is improved, but heat generation increases
Solution Approach 1:
The patent dynamically controls the switch to bypass the inrush current prevention resistor during high output modes when heat generation would be excessive. During low output modes, the resistor remains in the circuit to provide protection. This conditional switching resolves the contradiction between continuous safety and heat management.
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 reduces power consumption and heat generation by optimizing the operation of the inrush current prevention circuit, allowing for faster transitions between power modes and enhancing the responsiveness of image forming apparatuses by controlling the inrush current prevention circuit based on output power levels.
Implementation Method 1
a diode bridge is used to rectify an AC voltage supplied from a commercial power supply
Implementation Method 2
a smoothing capacitor is used to smooth the rectified voltage
Implementation Method 3
The inrush current prevention resistor 103 is configured to suppress the inrush current
Data Source
AI summary
Provided is a power supply apparatus, which is capable of saving power at the time of low output power even in a configuration using an inrush current prevention resistor and a switch as an inrush current prevention circuit in order to increase power of a low power supply. An AC/DC power supply includes a rectifier configured to rectify an input AC voltage, a smoothing capacitor configured to smooth the rectified voltage, a resistor configured to limit an inrush current input to the smoothing capacitor, a relay configured to control whether to input a current to the resistor, and a current detection circuit. The AC/DC power supply further includes a converter connected at the subsequent stage of the smoothing capacitor and configured to adjust the voltage smoothed by the smoothing capacitor to a predetermined voltage.