Multi-Mode Audio Power Amplifier With Feedback Current Sharing
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Solution Overview
Problem
Conventional audio power amplifiers lack versatility and efficiency in handling various connection topologies, load impedances, and power levels, requiring multiple amplifier products for different audio system configurations.
Innovation Solution
The design incorporates multiple amplification units with feedback loops and control electronics to operate in various configurations, including separate loads, parallel, and bridge-tied-load modes, using a four-quadrant power supply with a synchronous output rectifier, allowing for comprehensive configurability and high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional audio power amplifiers are designed for specific connection topologies and load impedances, then they can provide optimized performance for those specific configurations, but multiple amplifier products are required to handle different audio system configurations
Solution Approach 1:
The amplifier is designed with multiple amplification units (first and second units) that can be configured to operate in different modes: separate loads, parallel driving a common load, or bridge-tied-load configuration. This multi-functionality allows a single amplifier design to replace multiple specialized amplifier products, directly addressing the versatility versus complexity contradiction by enabling one device to perform multiple functions through configurable connection topologies and operational modes
2Loss of energy
If amplifiers operate in parallel driving a common load, then current sharing can reduce conduction loss, but complex control electronics are required to manage current distribution
Solution Approach 1:
The amplifier incorporates feedback loops that monitor and regulate current distribution among parallel amplification units. This feedback mechanism enables automatic current sharing to minimize conduction losses while the control electronics manage the complexity of coordinating multiple units, resolving the contradiction by using feedback to achieve energy efficiency despite the added control complexity
Data Source
AI summary
An audio power amplifier includes a first and a second amplification unit, each including a switching voltage amplifier, an output filter, a current compensator, an inner current feedback loop feeding a measurement of current measured at the output inductor back to a summing input of the current compensator, a voltage compensator coupled to the summing input of the current compensator, and an outer voltage feedback loop. A controlled signal path provides the output of the voltage compensator of the first amplification unit to the current compensator of the second amplification unit. The first and second amplification units are operable with separate loads, in parallel driving a common load, or across a bridge-tied-load. A second pair of amplification units may be added and operated together with the first pair to drive a single speaker with a parallel pair of amplifiers on each side of a bridge-tied-load.