Power Converter Voltage Shifter Eliminates Feedback Error Amplification
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Solution Overview
Problem
Existing power converter control solutions amplify errors in comparators and voltage references, affecting the regulation of output voltage due to voltage-division gain, leading to inaccuracies in voltage regulation and frequency compensation.
Innovation Solution
A control device for a power converter that includes a voltage shifter module to shift the output voltage into a low-voltage range and an amplification module to generate a control signal based on the difference between the shifted feedback voltage and a reference voltage, with a buffer module to maintain control voltage accuracy, eliminating attenuation and noise amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a voltage divider is used to generate feedback voltage from high-voltage output, then the feedback voltage is brought to low-voltage range for processing, but errors and noise are amplified by the voltage-division gain, degrading voltage regulation accuracy
Solution Approach 1:
Instead of dividing the high-voltage output to create feedback voltage (which amplifies errors), the patent inverts the approach by multiplying the low-voltage feedback signal by the inverse of the division ratio. This is achieved through an error amplifier that scales the feedback error signal, effectively canceling out the attenuation introduced by the voltage divider and eliminating error amplification.
Solution Approach 2:
The patent changes the parameter of feedback signal scaling by introducing a programmable gain amplifier or error amplifier with adjustable gain. This allows the feedback signal to be scaled appropriately to match the reference voltage level, enabling accurate voltage regulation without the error amplification problem inherent in fixed voltage divider configurations.
2Reliability
If hysteresis control is implemented to regulate output voltage between thresholds, then voltage regulation is achieved, but errors in comparator and voltage references are amplified, affecting regulation accuracy
Solution Approach 1:
The patent introduces an error amplifier as an intermediary between the voltage divider and the hysteresis comparator. This intermediary amplifies the feedback voltage to match the reference voltage level before comparison, ensuring that the comparator operates with accurate, properly-scaled voltages. This eliminates the error amplification problem while maintaining the stability benefits of hysteresis control.
3Stability of the object's composition
If a complex compensation network is used for frequency compensation in closed-loop control, then stability is improved, but device complexity increases
Solution Approach 1:
The patent extracts the frequency compensation function from a separate complex compensation network and integrates it directly into the error amplifier stage. By combining the amplification and compensation functions in a single integrated circuit block, the patent achieves the required stability without the complexity of external compensation components and networks.
Data Source
AI summary
A control device for a switching power converter having an inductor element, a switch coupled to the inductor element, a storage element coupled to an output on which an output voltage is provided, and a diode element coupled to the storage element. The control device generates a command signal to control the switch and determine storage of energy in the inductor element in a first interval, and transfer of energy onto the storage element through the diode element in a second interval. A voltage shifter module generates a feedback voltage shifted relative to the output voltage. An amplification module has a first input receiving the feedback voltage, a second input receiving the reference voltage, and an output that supplies, as a function of the difference between the feedback and reference voltages, a control signal. A control unit receives the control signal and generates the command signal to control the switch.