Power Converter Control Device for Current Mode Operation
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Solution Overview
Problem
Existing power converter circuits face challenges in reducing electric power consumption and improving power factor, particularly in DC/DC and AC/DC converters, due to the need for resistances and secondary windings to measure reactor currents, leading to increased power loss and circuit complexity, as well as frequent errors from constant reactor current slopes.
Innovation Solution
A control device for power converter circuits that calculates the peak value of the reactor current based on output and input voltages, predicting turn-on and turn-off timings without the need for resistances or secondary windings, using differential equations to control the converter operation in current critical mode and improve power factor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If resistance rL or secondary winding TL is used to measure reactor current, then current measurement is achieved, but electric power loss increases and circuit complexity increases
Solution Approach 1:
The patent uses reactor voltage vL as an intermediary measurement quantity instead of directly measuring reactor current iL. By measuring voltage across the reactor and using the relationship iL = ∫(vL/L)dt, the system achieves current measurement without inserting resistance or secondary windings, thereby eliminating the associated power losses and circuit complexity
Solution Approach 2:
The patent replaces physical measurement components (resistance rL or secondary winding TL) with an electrical measurement approach using voltage sensing and mathematical calculation. This substitution eliminates the need for physical current-sensing elements that cause power loss, using instead a voltage-based measurement system processed through control circuit calculations
2Measurement precision
If resistance rL or secondary winding TL is used to measure reactor current, then current measurement is achieved, but device complexity increases
Solution Approach 1:
The patent uses reactor voltage vL as an intermediary measurement quantity instead of directly measuring reactor current iL. By measuring voltage across the reactor and using the relationship iL = ∫(vL/L)dt, the system achieves current measurement without inserting resistance or secondary windings, thereby eliminating the associated power losses and circuit complexity
Solution Approach 2:
The patent extracts the measurement function from physical current-sensing components and relocates it to the control circuit through voltage measurement and mathematical processing. This separates the measurement function from the power circuit, eliminating the need for physical current-sensing elements and simplifying the overall circuit structure
3Ease of operation
If constant reactor current slope is used for control, then control simplicity is maintained, but measurement errors occur frequently
Solution Approach 1:
The patent transitions from assuming a constant reactor current slope to dynamically calculating the actual slope based on real-time reactor voltage measurements. The control circuit computes diL/dt = vL/L at each moment, allowing the system to adapt to changing operating conditions while maintaining control simplicity through automated calculation
Solution Approach 2:
The patent implements feedback by continuously measuring reactor voltage vL and using this information to update the reactor current calculation in real-time. The control circuit uses the measured voltage to compute the actual current slope and adjust timing accordingly, creating a closed-loop system that improves reliability while maintaining ease of operation
Data Source
AI summary
In DC/DC converter circuit, the peak value of the reactor current is found based on output voltage and an input voltage, thereby, the operation with the predetermined electric current mode is thereby enabled. The AC/DC converter circuit is run with a predetermined current mode, the power factor improvement is accomplished. The first control part 211 inputs a detected value of output voltage Eo, and a turn-off timing predicted value of switch Tr of the DC/DC converter 1 is calculated. The first control part 211 sends the calculation result to the switch drive signal generate part 213. The second control part 212 inputs the detected value of the output voltage and the input voltage, and it receives the turn-off timing predicted value from the first control part 211. Even more particularly, the second control part 212 calculates the peak value of the reactor current of the DC/DC converter 1 based on the turn-off timing predicted value, and it calculates the time that the reactor current decreases to a predetermined preset value from the peak value as a turn-on timing predicted value.