Capacitive Divider Circuit for Power Switch Voltage Spike Measurement
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Solution Overview
Problem
Existing DC/DC converters face challenges in efficiently managing voltage spikes during startup, particularly when transferring energy from a low-voltage side to a high-voltage side, which can lead to power switch damage and prolonged charging times due to limited current and inaccurate pre-charge control in active clamping circuits.
Innovation Solution
A startup control method and system that includes a voltage spike measurement circuit using a capacitive divider unit connected to a digital signal processor, allowing for real-time measurement and control of voltage spikes, enabling precise adjustment of driving signals to prevent overvoltage and optimize charging efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a large current is used to charge bus capacitors quickly, then charging time is reduced, but voltage spike of rectifier power switches exceeds the limit
Solution Approach 1:
The patent applies preliminary action by pre-charging the clamping capacitor before the rectifier power switches are activated. The control method includes: detecting whether the clamping capacitor voltage meets a preset condition; only when the condition is met, enabling the rectifier power switches. This preliminary pre-charge action prevents voltage spikes during startup by ensuring the clamping capacitor is ready to absorb transient energy before high current charging begins.
Solution Approach 2:
The patent implements feedback control by continuously monitoring the clamping capacitor voltage and using this information to control the switching of rectifier power switches. The control method detects the clamping capacitor voltage in real-time and adjusts the switching state accordingly - only enabling rectifier switches when the voltage meets preset conditions, thereby creating a closed-loop control system that prevents overvoltage while allowing efficient charging.
2Device complexity
If the clamping capacitor is not pre-charged or pre-charge control accuracy is poor, then device complexity is reduced, but power switches experience large current surge and voltage spike
Solution Approach 1:
The patent uses feedback control to accurately monitor the clamping capacitor voltage and compare it with a reference voltage. The control circuit only enables rectifier power switches when the detected voltage meets preset conditions, ensuring precise pre-charge control without adding excessive complexity. This feedback mechanism guarantees reliable power switch operation by preventing activation during unsafe voltage conditions.
Solution Approach 2:
The patent changes the voltage parameter of the clamping capacitor as a control variable. By setting a reference voltage and comparing the actual clamping capacitor voltage against this reference, the system dynamically adjusts the switching state of rectifier power switches. This parameter-based control approach provides accurate pre-charge management while maintaining relatively simple circuit implementation.
3Reliability
If low current is set on the low-voltage side to limit voltage spike, then power switch safety is ensured, but charging power is limited and startup time is prolonged
Solution Approach 1:
The patent applies preliminary action by pre-charging the clamping capacitor before enabling high-power charging through rectifier power switches. This preliminary preparation allows the system to subsequently handle large charging currents safely, as the pre-charged clamping capacitor is ready to absorb voltage spikes. Thus, the system can operate at high power without compromising power switch safety.
Solution Approach 2:
The patent uses feedback control to enable high-power charging while maintaining power switch safety. By continuously monitoring clamping capacitor voltage and only enabling rectifier switches when voltage conditions are met, the system allows maximum charging power to flow through the rectifier switches without risking overvoltage damage. This feedback mechanism decouples the traditional trade-off, enabling both high productivity and reliability simultaneously.
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
The solution significantly improves startup efficiency, reduces charging time, and ensures that voltage stress on power switches remains within safe limits, enhancing the overall performance and reliability of DC/DC converters.
Implementation Method 1
a capacitive divider unit comprising at least two capacitors connected in series, the capacitive divider unit receiving the rectified signal, dividing the rectified signal according to a capacitance ratio of the at least two capacitors
Implementation Method 2
a rectifier unit for receiving a voltage signal of a power switch, and outputting a rectified signal
Data Source
AI summary
A voltage spike measurement circuit for a power switch includes a rectifier unit, a capacitive divider unit and a discharge unit, the rectifier unit configured to receive a voltage signal at both ends of a power switch and output a rectified signal; the capacitive divider unit includes at least two capacitors connected in series and configured to receive the rectified signal, divide the rectified signal based on a capacitance ratio of the at least two capacitors, and output a divider signal to a digital signal processor to calculate a voltage spike measurement value of the power switch; and the discharge unit connected in parallel to the capacitive divider unit.