Power Converter Surge Voltage Suppression via Choke Coil Current Control
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Solution Overview
Problem
Conventional power converter control systems face challenges in suppressing surge voltage, particularly when the load varies and current in the second circuit decreases, leading to excessive reverse current and surge voltage issues.
Innovation Solution
A control apparatus that monitors the current through the choke coil and keeps the first-side switching element in an on state for a predetermined time before turning off the second-side switching elements, ensuring the current value exceeds a command value to manage surge voltage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the first-side switching element is kept in an on state during a predetermined time period before turning off the second-side switching element, then surge voltage is suppressed, but when the load varies and current decreases, excessive reverse current flows causing surge voltage
Solution Approach 1:
The control apparatus dynamically adjusts the timing control based on real-time current detection. When the current through the choke coil exceeds a predetermined threshold, the first-side switching element is kept in an on state before turning off the second-side switching element. This dynamic adjustment based on current conditions resolves the contradiction by applying the timing control only when necessary, preventing excessive reverse current while still suppressing surge voltage when needed.
Solution Approach 2:
The control apparatus uses current detection to obtain real-time current values through the choke coil and feeds this information back to the control unit. This feedback mechanism enables the system to determine whether to apply the timing control based on actual current conditions, thereby preventing excessive reverse current flow while maintaining surge voltage suppression effectiveness.
2Object-affected harmful factors
If current detection and conditional timing control are implemented, then surge voltage suppression is improved, but control complexity increases
Solution Approach 1:
The control apparatus implements preliminary timing control by keeping the first-side switching element in an on state during a predetermined time period before turning off the second-side switching element. This preliminary action prepares the circuit in advance to prevent surge voltage, and when combined with current-based conditional control, achieves effective surge suppression without excessive complexity.
Data Source
AI summary
A control apparatus is provided which controls a power converter including a first circuit including first-side switching elements, and a second circuit including second-side switching elements and a choke coil. The control apparatus includes a current obtainment unit which obtains a value of current flowing through the choke coil, and a control unit which, when power is supplied from the second circuit to the first circuit, keeps a first-side switching element ON during a predetermined time period, before turning off at least one second-side switching element in an on state, the first-side switching element generating a reverse current in the second-side switching element to be turned off. The control unit performs control of keeping the first-side switching element ON during the predetermined time period and control of turning off the second-side switching element, on condition that the obtained value of the current is more than a predetermined command value.