Surge Protection Device Mitigating Switch Bounce
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Solution Overview
Problem
Conventional surge protection devices face issues with switch bounce during operation, which can jeopardize back-end circuits, and they often fail to provide adequate protection for their own components, such as metal oxide varistors, leading to potential explosions and damage.
Innovation Solution
A surge protection device incorporating a pulse controlled switch, a pulse generation circuit, and an abnormal voltage detection circuit, which uses pulses to control the switch's state, ensuring reliable disconnection from the power line loop during abnormal voltages and efficient reconnection once safe, thereby preventing switch bounce and protecting both the device and the back-end circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal fuse is connected in series with the MOV to protect against excessive heat, then the MOV is protected from thermal damage, but the thermal fuse melts and disconnects the power line loop before the MOV can be protected, causing the surge protection device to fail
Solution Approach 1:
The patent replaces the thermal fuse's thermal-mechanical protection mechanism with an electronic control system comprising a voltage detection circuit, pulse generation circuit, and pulse-controlled switch. The voltage detection circuit detects abnormal voltages and generates control pulses to open the switch, providing faster electronic response compared to the thermal fuse's slow thermal response. This substitution enables timely protection of the MOV before thermal damage occurs.
2Object-affected harmful factors
If a switching element is used to disconnect the power line loop during abnormal voltage, then back-end circuit is protected from surge, but switch bounce occurs at the operating point which jeopardizes the back-end circuit
Solution Approach 1:
The patent employs periodic pulse signals from the pulse generation circuit to control the switching element. The pulse-controlled switch responds to periodic pulses that maintain it in a stable open state during abnormal voltage conditions, preventing switch bounce. The periodic nature of the pulse signal ensures reliable switching operation without the instability associated with conventional switching elements.
3Reliability
If an over-voltage protection circuit with hysteresis is added to prevent switch bounce, then long-time abnormal voltage is protected, but the circuit cannot handle excessive voltage fluctuations or transient surges that occur from time to time
Solution Approach 1:
The patent implements a dynamic protection mechanism where the pulse generation circuit generates control pulses based on real-time voltage detection. Unlike fixed hysteresis circuits, this dynamic system can adapt its response to different voltage conditions including transient surges and fluctuations. The pulse-controlled switch dynamically adjusts its state based on the detected voltage conditions, providing both stability for long-time abnormal voltage and responsiveness to transient events.
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 effectively mitigates switch bounce, ensures the surge protection device can be restored after voltage recovery, and is energy-efficient by maintaining controlled states with pulses, providing comprehensive protection and reducing the risk of damage to both the device and connected equipment.
Implementation Method 1
The pulse generation circuit has an input terminal and an output terminal. The input terminal is adapted to connect to the power line loop and is located in a front end of the pulse controlled switch. The output terminal is connected to the at least one control terminal of the pulse controlled switch.
Implementation Method 2
The abnormal voltage detection circuit has at least one detection input terminal and an output terminal. The at least one detection input terminal is adapted to connect to the power line loop and is located in a back-end of the pulse controlled switch.
Implementation Method 3
The pulse controlled switch is adapted to connect in series to a power line loop and has at least one control terminal. When continuously detecting abnormal voltage in the power line loop, the abnormal voltage detection circuit sends a pulse to the pulse controlled switch to open the pulse controlled switch and disconnect to the power line loop
Data Source
AI summary
A surge protection device has a pulse controlled switch, a pulse generation circuit and an abnormal voltage detection circuit. The surge control switch is connected in series to a power line loop and has at least one control terminal respectively connected to output terminals of the pulse generation circuit and the abnormal voltage detection circuit. An output terminal of the abnormal voltage detection circuit is connected to the power line loop and is located in the back end of the pulse controlled switch. The pulse generation circuit serves to send a pulse to the pulse controlled switch to close the pulse controlled switch and connect to the power line loop. When continuously detecting abnormal voltage in the power line loop, the abnormal voltage detection circuit opens the pulse controlled switch and disconnects from the power line loop so as to protect back-end equipment or circuit.