Power Conversion Apparatus Cable Loss Compensation
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Solution Overview
Problem
Current power conversion apparatuses face limitations in cable loss compensation, particularly during overload operations in continuous conduction mode (CCM), as existing methods either rely on fixed turn-off periods or additional power consumption through current detection circuits, which are not effective in both discontinuous and continuous conduction modes.
Innovation Solution
A power conversion apparatus incorporating a cable loss compensation circuit that utilizes a synchronous rectification control signal to generate a compensation current, allowing effective voltage compensation in both DCM and CCM without additional power consumption by directly detecting output current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a current detection circuit is used to detect output current for cable loss compensation, then cable loss compensation accuracy is improved, but power consumption increases
Solution Approach 1:
The synchronous rectification control signal already contains information about the output current magnitude. The cable loss compensation circuit uses this existing signal directly without requiring separate current detection, making the system self-sufficient and eliminating additional power consumption for current sensing
Solution Approach 2:
The synchronous rectification control signal serves dual purposes: controlling the synchronous rectification transistor and providing information for cable loss compensation. This multi-functionality eliminates the need for dedicated current detection circuitry
2Device complexity
If cable loss compensation is implemented using turn-off period detection, then implementation simplicity is improved, but applicability is limited to discontinuous conduction mode only
Solution Approach 1:
The synchronous rectification control signal maintains its relationship with output current magnitude across both discontinuous and continuous conduction modes. The compensation circuit designed based on this signal can therefore operate universally in both modes without requiring different implementation approaches
Solution Approach 2:
The circuit responds to changes in the synchronous rectification control signal characteristics that occur with different conduction modes and load conditions. By designing the compensation circuit to respond to these parameter variations, it achieves adaptability across operating modes
3Power
If output current is increased to meet higher power demand, then power delivery capability is improved, but voltage drop on output line increases causing cable loss
Solution Approach 1:
The cable loss compensation circuit continuously monitors the synchronous rectification control signal, which reflects the actual output current magnitude. Based on this feedback, the circuit dynamically adjusts the compensation amount to counteract the voltage drop caused by cable resistance, ensuring stable output voltage even at high power delivery
Solution Approach 2:
The compensation circuit proactively counteracts the expected voltage drop by adding a compensating voltage based on the detected output current level. This preliminary anti-action prevents the output voltage from falling below specifications before the problem occurs
Data Source
AI summary
A power conversion apparatus includes a power conversion circuit, a synchronous rectification transistor, a synchronous rectification control circuit, a feedback circuit, and a cable loss compensation circuit. The power conversion circuit converts an input voltage into an output voltage and provides it to a load. The synchronous rectification transistor is coupled in series to a current path on a secondary side of the power conversion circuit and switched according to a synchronous rectification control signal. The synchronous rectification control circuit generates the synchronous rectification control signal for controlling the switching of the synchronous rectification transistor. The feedback circuit generates an output indication current associated with the output voltage. The cable loss compensation circuit draws a compensation current from the feedback circuit according to the synchronous rectification control signal, so as to compensate for the output voltage based on a sum of the compensation current and the output indication current.