Power Source Apparatus with PFC Control for Busy Sound Suppression
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Solution Overview
Problem
Existing power source apparatuses generate a 'busy sound' due to over-current control during activation and instantaneous stop phases, which is not effectively addressed by increasing the number of terminals and external components, and these measures do not prevent the sound during power source activation or stop phases.
Innovation Solution
A power source apparatus with a control circuit that manages the ON-time of a switching element in a PFC converter, using a choke coil, diode, and output capacitor, to limit current flow and prevent the 'busy sound' by controlling the switching element's operation based on output voltage and activation state, without increasing the number of terminals or components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a soft-start terminal or current-limiting resistor with relay circuit is added to prevent busy sound during activation, then the busy sound is suppressed, but the number of terminals and external components increases
Solution Approach 1:
The control circuit automatically detects the output voltage level and adjusts the switching element's ON-time accordingly. During activation when output voltage is low, the ON-time is limited to prevent large current and busy sound. This self-regulating mechanism eliminates the need for external current-limiting components or soft-start terminals while effectively suppressing busy sound.
Solution Approach 2:
The invention dynamically changes the ON-time parameter of the switching element based on the output voltage detection. By adjusting this control parameter according to the activation state and output voltage level, the system prevents busy sound during activation and instantaneous stop without requiring additional physical components.
2Object-affected harmful factors
If conventional measures are taken to prevent busy sound during activation, then the busy sound is suppressed during activation, but the busy sound is not prevented during instantaneous stop phase
Solution Approach 1:
The control circuit performs multiple functions: it detects output voltage, determines activation state, adjusts ON-time dynamically, and suppresses busy sound across all phases including activation, normal operation, and instantaneous stop recovery. This universal control mechanism replaces multiple phase-specific protection circuits.
Solution Approach 2:
The control circuit continuously monitors the output voltage and uses this feedback to adjust the switching element's ON-time in real-time. This feedback mechanism enables the system to adapt to different operating phases (activation, normal operation, instantaneous stop) and maintain busy sound suppression throughout all transitions.
3Power
If the switching element operates with shorter ON-time during over-current protection, then the current is limited, but the switching frequency increases causing busy sound
Solution Approach 1:
The control circuit performs preliminary detection of the output voltage level before controlling the switching element. During activation when output voltage is below the predetermined level, the control circuit preemptively limits the ON-time to prevent large current flow and subsequent busy sound, rather than reacting after over-current occurs.
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 effectively prevents the generation of 'busy sound' during both activation and instantaneous stop phases, reducing the need for additional components and enhancing power source quality.
Implementation Method 1
a rectifying circuit for rectifying an alternating current voltage supplied from an alternating current power source
Implementation Method 2
a first converter including a switching element for converting the alternating current voltage into a first direct current voltage
Implementation Method 3
a second converter for converting the first direct current voltage obtained in the first converter into a second direct current voltage
Data Source
AI summary
A power source apparatus includes: a first alternating current line; a second alternating current line; an electric power inputting portion including a rectifying circuit for rectifying an alternating current voltage supplied from an alternating current power source, the electric power inputting portion serving to output the rectified voltage to each of the first and second alternating current lines; a first converter including a switching element for converting the alternating current voltage into a first direct current voltage; a second converter for converting the first direct current voltage obtained in the first converter into a second direct current voltage; and a control circuit for carrying out control for driving at least the switching element of the first converter so as to be turned ON or OFF.