Power Supply Stage Overvoltage Protection Segmentation
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Solution Overview
Problem
Existing battery charger power supply stages face challenges in providing effective overvoltage protection with high reaction speed and affordability, particularly in single-phase electronic systems connected to three-phase power supplies, where loss of neutral can lead to dangerous voltage fluctuations.
Innovation Solution
The power supply stage incorporates an electronic switch within the power factor correction circuit to quickly protect capacitors from overvoltages and an additional electromechanical switch or ignition current limiter to safeguard other components, ensuring rapid response and efficient protection without the need for manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If an electronic switch is used for overvoltage protection, then the reaction speed is improved, but the component dissipation and cost increase
Solution Approach 1:
The protection system is segmented into two distinct switches: an electronic switch (MOSFET or IGBT) for rapid response to overvoltage events, and an electromechanical switch for sustained circuit interruption. This segmentation allows each component to be optimized for its specific function, reducing the burden on the electronic switch and thereby reducing its dissipation.
Solution Approach 2:
The electronic switch performs only the critical initial action of rapid response to overvoltage, while the electromechanical switch handles the sustained protection function. This partial action approach allows the electronic switch to operate briefly at high speed without excessive dissipation, as the electromechanical switch takes over for longer-term protection.
2Reliability
If a switch with high reaction speed is used, then the protection effectiveness is improved, but the device complexity increases
Solution Approach 1:
The protection function is segmented between two specialized switches rather than using a single complex switch. The electronic switch (MOSFET or IGBT) provides rapid response capability, while the electromechanical switch provides reliable sustained interruption. This segmentation achieves high protection effectiveness without requiring a single overly complex device.
Solution Approach 2:
The control circuit acts as an intermediary that coordinates the operation of the two switches. It detects overvoltage conditions and triggers both the electronic switch for immediate response and the electromechanical switch for sustained protection, simplifying the overall control logic while achieving reliable protection.
3Reliability
If an overcurrent breaker is used for line interruption, then the protection reliability is improved, but the ease of operation worsens due to manual intervention requirement
Solution Approach 1:
The system employs a resettable thermal magnetic switch instead of a fuse, enabling automatic reset functionality. After an overvoltage event is cleared, the thermal magnetic switch can be reset without manual intervention or component replacement, allowing the system to restore operation automatically or with minimal user action.
Solution Approach 2:
The thermal magnetic switch can be reset and reused after tripping, unlike a fuse that must be replaced. This recovering capability eliminates the need for manual intervention to replace protection components, improving ease of operation while maintaining protection reliability.
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 configuration provides effective overvoltage protection for battery chargers, particularly in electric vehicles, with rapid response times and minimal component dissipation, maintaining system integrity while keeping costs affordable.
Implementation Method 1
a switch SW, the type of an electronic switch, connected in series to a smoothing capacitor C of the power factor correction circuit PFC
Implementation Method 2
an additional switch SW2, of the type of an electromechanical switch, arranged in series and upstream of the input filter F
Data Source
Figure 1~3
Figure 4
Figure 5
AI summary
The power supply stage (A) of an electric appliance, in particular battery chargers for charging batteries of electric vehicles or the like, comprises a power factor correction circuit (PFC), and overvoltage protection means equipped with: - a switch (SW1) connected in series with a smoothing capacitor (C) of the power factor correction circuit (PFC); - a control circuit (VD 1 ) of the input voltage of the power supply stage (A) operatively connected to the switch (SW1).