Public Address Amplifier Power Buffering Under PoE Limits
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Solution Overview
Problem
Public address devices face challenges in maintaining sufficient loudspeaker output while controlling power consumption to avoid exceeding the upper-limit supply power from a power source device, especially when the power source capacity is insufficient, leading to issues with sound recognition and compliance with standards like PoE.
Innovation Solution
A public address device is configured with a voltage transforming unit, power amplifier, power detection unit, threshold holding unit, voltage control unit, and charge accumulation unit to control output voltage and supply power, ensuring input power does not exceed the upper-limit supply power, and includes features like current detection and amplitude limitation to secure necessary loudspeaker output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If power source voltage is dropped to suppress power consumption, then power consumption is reduced, but loudspeaker output drops making it difficult for listeners to recognize sound
Solution Approach 1:
The charge accumulation unit accumulates electrical charge in advance during periods when power consumption is low. This preliminary accumulation of energy enables the power amplifier to maintain high output power during critical sound output periods without exceeding the upper-limit supply power, thus resolving the contradiction between power consumption control and sound recognition quality.
2Power
If power source voltage is determined for square wave to prevent exceeding upper-limit supply power, then power consumption is controlled, but only 50% of upper-limit supply power can be used for sine wave signals
Solution Approach 1:
The system dynamically adjusts the power source voltage based on the actual power consumption requirements of the power amplifier. By using the charge accumulation unit to provide supplemental power, the voltage can be maintained at levels that optimize loudspeaker output for different signal types (sine wave, square wave) without being constrained by the conservative square-wave-based voltage determination, thus improving productivity while maintaining power control.
3Reliability
If power source supply is stopped and reset is performed to comply with PoE standards when power consumption exceeds upper-limit supply power, then compliance is maintained, but sufficient loudspeaker output cannot be secured
Solution Approach 1:
The charge accumulation unit accumulates electrical charge in advance during periods when power consumption is within the upper-limit supply power. This preliminary energy storage enables the system to maintain continuous operation and provide sufficient loudspeaker output during brief periods when power consumption temporarily exceeds the limit, avoiding the need to stop power supply and reset, thus maintaining both PoE compliance and output continuity.
4Power
If power source capacity of power source device is insufficient, then power supply is limited, but power consumption fluctuation still causes problems
Solution Approach 1:
The charge accumulation unit acts as an intermediary energy storage device between the power source device and the power amplifier. It buffers the fluctuations in power consumption by releasing stored charge during high-demand periods and absorbing excess charge during low-demand periods, thereby stabilizing the power supply to the power amplifier even when the power source device has insufficient capacity.
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 configuration allows for effective power control, ensuring listeners can recognize sound without exceeding the upper-limit supply power, even during continuous sound output, and maintains compliance with power standards like PoE, thereby securing sufficient loudspeaker output.
Implementation Method 1
a voltage transforming unit that performs voltage transformation of a direct-current power source input from a power source device
Implementation Method 2
a charge accumulation unit that is connected between the voltage transforming unit and the power amplifier, and supplies a power source to the power amplifier when the output voltage of the voltage transforming unit drops
Implementation Method 3
a power amplifier that amplifies a sound signal using the direct-current power source after the voltage transformation to generate a driving signal
Implementation Method 4
a loudspeaker that converts the loudspeaker driving signal into a sound wave
Data Source
AI summary
Provided is a public address device that facilitates recognizing a sound while performing power control so that input power does not exceed upper-limit supply power of a power source device. Included are a voltage transforming unit 204 that performs voltage transformation of a direct-current power source input from a power source device 10; a power amplifier 202 that amplifies a sound signal using the direct-current power source after the voltage transformation to generate a driving signal that drives an electroacoustic transducer; a power detection unit 205 that detects input power from the power source device 10; a threshold holding unit 207 that holds a power determination threshold Pth corresponding to upper-limit supply power of the power source device 10; a voltage control unit 206 that controls an output voltage of the voltage transforming unit 204 on the basis of the input power Pi and the power determination threshold Pth; and a charge accumulation unit 208 that is connected between the voltage transforming unit 204 and the power amplifier 202, and supplies a power source to the power amplifier 202 when the output voltage of the voltage transforming unit 204 drops.