Dynamic Over-Current Protection for Power Converters
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Solution Overview
Problem
Current over-current protection systems in power converters are limited by a fixed reference current, preventing the power converter from operating at maximum voltage limits, as increasing voltage range results in protection halting the power stage due to voltage peaks that can damage switching devices.
Innovation Solution
A dynamic over-current protection system that adjusts the reference current based on real-time DC voltage and leakage inductance, using a comparator and control device to measure output current and voltage, and a test generator to calculate and apply adaptive pairs of voltage-current values, allowing the power stage to operate closer to maximum voltage without damaging the switching devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed reference current is used for over-current protection, then the switching devices are protected from damage, but the power converter cannot operate at maximum voltage limits
Solution Approach 1:
The patent applies dynamics by transforming the fixed reference current into a dynamic reference current that varies with the DC voltage level. The control device continuously adjusts the reference current based on the measured DC voltage, enabling the protection system to adapt to different operating conditions. This allows the power converter to operate at maximum voltage limits while maintaining protection, as the reference current automatically scales with the voltage to prevent over-current damage to switching devices.
Solution Approach 2:
The patent changes the parameter of reference current from a fixed value to a variable value that depends on the DC voltage. By establishing a relationship between DC voltage and reference current (where reference current increases with DC voltage), the system enables expanded voltage operating range while maintaining protection. The control device modifies the reference current parameter dynamically based on real-time voltage measurements, resolving the contradiction between protection reliability and voltage adaptability.
2Power
If the reference current is increased to allow higher power operation, then the power output increases, but the switching devices may be damaged by voltage peaks during halts
Solution Approach 1:
The patent implements feedback by having the control device continuously measure the DC voltage and use this information to adjust the reference current. The measured DC voltage feeds back to the control device, which then determines the appropriate reference current level. This feedback mechanism ensures that the reference current is always appropriate for the current operating voltage, allowing high power operation when voltage is high while preventing over-current damage when voltage is lower, thus resolving the contradiction between power output and switching device integrity.
Solution Approach 2:
The patent applies preliminary action by pre-establishing the relationship between DC voltage and reference current before operation. The control device is configured to determine the reference current based on the measured DC voltage before any over-current condition occurs. This preliminary setup of the reference current based on voltage level ensures that protection is already in place at the appropriate level before high power operation begins, preventing switching device damage while enabling high power output.
Data Source
AI summary
The invention discloses a system and a method for dynamic over-current protection for power converters. The system can be connected to the output of a power stage and comprises: a comparator that measures an output current (IOUT) of the power stage; a control device that measures a voltage (VDC) of the power stage; a test generator that comprises pairs of voltage-current values (VDC-IREF) that relate voltage values with current values of the power stage, where the test generator receives the measured voltage value from the control device and sends the corresponding current value from the pairs of voltage-current values to the comparator, which halts the power stage if the output current of the power stage is higher than or equal to the value of the current associated with the measured voltage.