Active Control Based on an Estimator for the Bus-Pumping Cancellation in the Half-Bridge Class-D Audio Power Amplifiers
In this paper is presented a new technique to avoid the distortion generated due to mid point voltage variations on DC-Bus of Class-D Half Bridge audio amplifiers. An usual distortion source on Class-D amplifier is the Bus-Pumping effect. Bus-Pumping causes characteristic distortion and introduces attenuation on output gain. Due to this effect the amplifier efficiency decreases. By including distortion factors on the Half-Bridge amplifier model a new Hybrid Active Control (HAC) is implemented. The HAC minimizes distortion due to mid point DC-Bus voltage variations. Simulation and experimental results confirm the theoretical approach of parameter influence on Bus-Pumping, and the effectiveness of HAC implemented control. Results show a clear reduction of generated distortion, which allows incremented audio amplifier efficiency.
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