DC/DC Converter Startup Control for Voltage Spike-Limited Reverse Charging
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Solution Overview
Problem
In switching power supplies, particularly in DC/DC converters, voltage spikes pose a risk to power switches, and existing methods fail to monitor and control them effectively, leading to potential damage and limited charging efficiency, especially during startup processes in electric vehicles.
Innovation Solution
A startup control method and system for DC/DC converters that includes determining a duty cycle or frequency of a driving signal based on voltage spike reference and measurement values, using a compensator and driving signal generator to control power switches, and a voltage spike measurement circuit with a capacitive divider unit to accurately measure and manage voltage spikes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low current of the low-voltage side is set to ensure the voltage spike of the rectifier power switch does not exceed the limit, then the voltage stress on the power switch is reduced, but the charging power is limited and the charging time is long
Solution Approach 1:
The patent applies dynamic control by adjusting the duty cycle of the driving signal based on real-time voltage spike measurements. The control system dynamically modifies the operating parameters during startup to optimize both voltage stress and charging power, transitioning from static low-current limitation to adaptive current control that responds to actual voltage conditions.
Solution Approach 2:
The patent implements feedback control through voltage spike measurement circuits that continuously monitor the voltage stress on power switches during startup. The measured voltage spike values are fed back to the control system, which then adjusts the driving signal parameters accordingly, creating a closed-loop control mechanism that balances voltage protection with charging efficiency.
2Device complexity
If the clamping capacitor is not pre-charged or pre-charge control accuracy is poor, then the circuit is simpler, but the power switch has large current surge and the rectifier power switch has large voltage spike
Solution Approach 1:
The patent enables the clamping capacitor to self-charge through the transformer's leakage inductance during the startup process. The control system monitors the voltage spike and automatically adjusts the driving signal to facilitate the capacitor's charging, eliminating the need for separate pre-charge circuits while ensuring accurate voltage control through feedback mechanisms.
3Device complexity
If switching power supply does not monitor the voltage spike of the power switch in real time, then the device complexity is reduced, but the power switch may be damaged when voltage spike exceeds the maximum allowable working voltage
Solution Approach 1:
The patent replaces complex mechanical monitoring systems with electronic measurement circuits that use capacitive dividers and voltage detection circuits to monitor voltage spikes. This electronic approach provides real-time voltage monitoring with minimal added complexity, enabling continuous protection of power switches through electrical signal processing rather than mechanical intervention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution improves startup efficiency, reduces startup time, and ensures voltage stress on power switches does not exceed limits, enhancing charging power and accuracy in pre-charging clamping capacitors.
Implementation Method 1
a capacitive divider unit configured with at least two capacitors in series, the capacitive divider unit dividing a voltage spike signal according to a capacitance ratio of the at least two capacitors, and outputting a divider signal to a digital signal processor to calculate a voltage spike measurement value of the power switch
Data Source
AI summary
A startup control method for a DC/DC converter is used for starting the DC/DC converter with energy transferred from a low-voltage side to a high-voltage side, and includes: determining a duty cycle or a frequency of a driving signal based on at least a voltage spike reference value and a voltage spike measurement value of a power switch at the low-voltage side; and outputting the driving signal to the power switch, thereby controlling the on and off of the power switch. The startup control method for a DC/DC converter of the disclosure can improve a reverse charging power of the converter to the maximum extent and reduce the time needed for charging a bus capacitor during a reverse startup process while ensuring voltage stress on the power switch not to exceed a limit.