Power Conversion Control Using Duty Ratio and Output Voltage
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Solution Overview
Problem
Existing methods for distinguishing between continuous and discontinuous current modes in power conversion circuits rely on reactor current detection, which can lead to erroneous distinctions due to sensor errors, especially when the discontinuous current mode is characterized by small reactor current values.
Innovation Solution
A control device for a power conversion circuit that determines the operation mode without using reactor current detection values by analyzing changes in duty ratio and output voltage detection values, specifically through a duty ratio increase/decrease distinguishment unit and an output voltage detection value increase/decrease distinguishment unit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If reactor current detection is used to distinguish between continuous and discontinuous current modes, then the current mode can be identified, but sensor errors cause erroneous distinguishment especially when reactor current values are small
Solution Approach 1:
The patent introduces output voltage detection values as an intermediary parameter to indirectly determine current mode. Instead of directly measuring reactor current with a sensor, the system uses the relationship between output voltage changes and duty ratio changes to infer whether the circuit is in continuous or discontinuous current mode, thereby avoiding sensor errors
Solution Approach 2:
The patent replaces the physical current sensor measurement system with an electrical calculation system. By substituting the mechanical/electrical sensing of reactor current with computational analysis of output voltage and duty ratio relationships, the system eliminates sensor-related errors while maintaining mode distinction capability
2Measurement precision
If the discontinuous current mode is detected using small reactor current values, then the mode can be identified, but sensor errors significantly impact detection accuracy
Solution Approach 1:
The patent uses output voltage detection values as an intermediary to detect discontinuous current mode. By monitoring whether output voltage detection values increase when duty ratio increases, the system can identify discontinuous mode without directly measuring small reactor current values, thereby eliminating sensor error impact
Solution Approach 2:
The patent changes the detection parameter from reactor current to output voltage. This parameter substitution allows the system to detect discontinuous current mode through voltage characteristics rather than current magnitude, avoiding the harmful effect of sensor errors on small current measurements
Data Source
AI summary
A feedback control unit includes a controller which calculates a duty ratio for switching elements on the basis of a command value and a detection value of electrical information. A continuous/discontinuous current mode distinguishment unit includes a duty ratio increase/decrease distinguishment unit which performs distinguishment between increase and decrease in the duty ratio, and an output voltage detection value increase/decrease distinguishment unit which performs distinguishment between increase and decrease in a detection value of a voltage of second terminals. If the duty ratio has decreased and the detection value of the voltage has increased, or if the duty ratio has increased and the detection value of the voltage has decreased, the continuous/discontinuous current mode distinguishment unit determines that an operation mode is a discontinuous current mode, and feeds back a result of the determination to the feedback control unit.