Switched Mode Power Supply Current Integration Control
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Solution Overview
Problem
Switching power converters face excessive power dissipation due to inherent switch-off delays and comparator circuit delays, which are not adequately compensated for in existing solutions, leading to over-shooting of input current and inefficient operation across both discontinuous and continuous current modes.
Innovation Solution
A switching power converter design that integrates the current sense signal and compares it with a threshold signal that is a function of the input voltage, using a control circuit with a threshold generator, integrator, and comparator to periodically switch on and off the semiconductor switch based on the integrated current sense signal, thereby reducing power dissipation across varying input voltage ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a conventional current control method with fixed threshold is used, then the circuit complexity is low, but excessive power dissipation occurs due to switch-off delays and current over-shooting
Solution Approach 1:
The control circuit performs preliminary integration of the current sense signal before comparison with the threshold. This preliminary action (integration) allows the system to anticipate the current over-shoot that would occur during switch-off delay, enabling the switch to be turned off before the current actually reaches the threshold level, thus preventing excessive power dissipation.
Solution Approach 2:
The patent applies dynamic threshold adjustment based on operating conditions. The control circuit adapts its behavior by integrating the current signal over time, effectively creating a dynamic threshold that accounts for the inherent delays in the system. This dynamic approach allows optimal switching control across different operating modes (DCM and CCM) without requiring separate fixed thresholds for each mode.
2Adaptability or versatility
If separate control methods are designed for DCM and CCM, then the control can be optimized for each mode, but the device complexity increases and adaptability across modes is reduced
Solution Approach 1:
The patent implements a universal control approach where the integrator and fixed threshold comparison circuit can operate across both DCM and CCM modes. The integration process naturally adapts to the different current waveforms in each mode, providing mode-independent control that eliminates the need for separate control circuits for DCM and CCM, thus maintaining adaptability while reducing complexity.
Solution Approach 2:
The control method changes the parameter being compared from direct current magnitude to integrated current over time. This parameter transformation allows the same control circuit to effectively handle both discontinuous and continuous current modes, as the integration process inherently accounts for the different current profiles in each mode without requiring mode-specific adjustment.
3Loss of energy
If the switch-off threshold is set to compensate for delays, then power dissipation is reduced in one mode, but the control precision deteriorates in other modes
Solution Approach 1:
The patent replaces the mechanical approach of adjusting fixed threshold voltages with an electronic integration process. Instead of manually setting different threshold levels to compensate for delays, the system uses an integrator circuit that automatically processes the current signal over time, providing precise control without sacrificing measurement accuracy. The integration mathematically accounts for delay effects while maintaining faithful representation of the actual current behavior.
Data Source
AI summary
A switching power converter includes an inductor coupled to a terminal operably supplied with an input voltage. A semiconductor switch is coupled to the inductor and configured to enable and disable an input current passing through the inductor in accordance with a drive signal. A current sense circuit is coupled to the inductor or the semiconductor switch and is configured to generate a current sense signal representing the input current passing through the inductor or the semiconductor switch. A control circuit receives the current sense signal and is configured to: close the semiconductor switch regularly in accordance with a clock frequency, to integrate the current sense signal thus providing an integrated current sense signal to compare the integrated current sense signal with a threshold that is a function of the input voltage.