Pulse Modulated Converter Feedback for Low Distortion Bandwidth
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Solution Overview
Problem
Existing pulse width modulated (PWM) amplifiers face issues with high distortion, restricted bandwidth, and load dependency due to non-linearities in triangular generators and self-oscillating modulators, which compromise stability and efficiency.
Innovation Solution
A pulse modulated converter system utilizing two feedback signals, one derived from the power stage and another from the output, with predetermined transfer functions to achieve high loop gain and low output impedance, allowing for linear modulation and reduced switching frequency variation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a self-oscillating modulator is used to eliminate triangular generator non-linearities, then bandwidth and loop gain are improved, but output impedance and distortion increase due to lack of demodulation filter control
Solution Approach 1:
The patent implements a feedback mechanism where the output of the demodulation filter is fed back to the modulator input. This feedback loop allows the system to control and correct the output impedance and distortion caused by the self-oscillating modulator, while maintaining the high bandwidth and loop gain benefits. The feedback signal provides error correction that compensates for the non-linearities introduced by the modulator.
2Speed
If a self-oscillating modulator with local loop feedback is used, then bandwidth increases, but distortion increases due to non-linearities of the output filter component
Solution Approach 1:
The patent uses feedback from the demodulation filter output to the modulator input to correct the distortion introduced by the output filter component. This feedback mechanism allows the system to maintain high bandwidth while compensating for the non-linearities and distortion caused by the filter, thereby reducing overall system distortion.
3Measurement precision
If ordinary non-oscillating global loop feedback is used, then sensitivity decreases, but load step and step response capabilities are reduced
Solution Approach 1:
The patent employs a self-oscillating modulator that dynamically adjusts its operation based on the feedback signal. This dynamic behavior allows the system to maintain high sensitivity for accurate signal detection while simultaneously providing fast load step and step response capabilities. The self-oscillation characteristic enables the system to respond quickly to changes without sacrificing sensitivity.
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 system achieves low distortion, high stability, and efficient utilization of power supply rail voltage with reduced component size and power consumption, operating at high modulation indexes with improved noise rejection and frequency response.
Implementation Method 1
means for providing a hysteresis when generating the pulse width modulated signal
Data Source
AI summary
A pulse modulated converter comprising an input stage (1) for generating a first control signal (2) based on an input signal (3) and a first feedback signal (4), and a comparator (5) for generating a pulse width modulated signal (6) based on said first control signal and a reference signal (7), means for providing a hysteresis when generating the pulse width modulated signal (6), a power stage (8) for generating an amplified pulse width modulated signal (9), an output filter (10) for filtering said amplified pulse width modulated signal (9), so as to create an analog output signal (11). In said pulse modulated converter, the first feedback signal (4) is formed as a combination of a second feedback signal (12) and a third feedback signal (13). The second feedback signal (12) is derived from the amplified pulse width modulated signal (9) using a first predetermined transfer function (14). The third feedback signal (13) is derived from the analog output signal (11) using a second predetermined transfer function (15). The second predetermined transfer function (15) comprises at least one zero.