Adaptive MOV Surge Suppressor Circuit for Semiconductor Overvoltage Protection
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Solution Overview
Problem
Existing overvoltage protection techniques for semiconductor devices, such as those using metal oxide varistors (MOVs), often result in a mismatch between maximum clamping voltage and continuous operating voltage, leading to inadequate protection and reduced power utilization of semiconductor devices.
Innovation Solution
An adaptive voltage surge suppressor circuit that includes a string of series-connected voltage clamp devices, with a bypass circuit and control circuit to selectively bypass a subset of these devices, allowing for dynamic adjustment of clamping voltage based on the voltage applied to the semiconductor device, ensuring protection within the device's maximum instantaneous and continuous operating ratings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an MOV with high clamping voltage is used to protect semiconductor devices, then the device can operate at higher continuous voltage, but the clamping voltage may exceed the device's instantaneous voltage rating and provide inadequate protection
Solution Approach 1:
The voltage clamp protection is divided into multiple discrete MOV elements connected in series, allowing independent control of each segment through associated switches. This segmentation enables selective activation of protection levels based on voltage conditions, resolving the contradiction between continuous operating voltage capability and instantaneous protection.
Solution Approach 2:
The protection circuit transitions from a static MOV configuration to a dynamic system where switches can selectively bypass individual MOV segments based on real-time voltage conditions. This dynamic adjustment allows the circuit to adapt between different protection modes, providing both continuous operating capability and instantaneous overvoltage protection.
2Reliability
If an MOV with low continuous operating voltage rating is used, then the device can be protected within its continuous voltage rating, but the clamping voltage must be set lower reducing protection effectiveness for high voltage transients
Solution Approach 1:
The circuit dynamically reconfigures the MOV string configuration by selectively bypassing segments based on operating conditions. During normal operation, all MOV segments are active to maintain continuous voltage compliance. During transient events, switches bypass segments to provide lower clamping voltage for enhanced protection effectiveness.
Solution Approach 2:
The circuit changes its electrical parameters (clamping voltage, continuous operating voltage) by reconfiguring the MOV string through switches. This allows the same protection circuit to operate at different parameter sets depending on whether it's protecting against continuous voltage or transient spikes.
3Device complexity
If a single MOV is used for voltage clamping, then the circuit is simple, but it cannot dynamically adjust clamping voltage to match device ratings under varying operating conditions
Solution Approach 1:
The single MOV is segmented into multiple series-connected elements, each with its own bypass switch. This segmentation increases adaptability while keeping each individual segment simple, allowing selective activation based on voltage conditions without requiring complete circuit redesign.
Solution Approach 2:
Each MOV segment serves multiple functions: it provides continuous voltage clamping during normal operation and can be selectively bypassed during transient events. The associated switches provide dual functionality by either being open (allowing MOV operation) or closed (bypassing the MOV segment).
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 provides enhanced overvoltage protection for semiconductor devices, allowing them to operate at full power utilization while preventing damage from voltage transients, by dynamically adjusting the clamping voltage to match the device's ratings, thereby improving protection and efficiency.
Implementation Method 1
metal oxide varistors (MOVs), which generally are fast transient voltage suppression power devices, but typically exhibit a non-linear clamping voltage versus clamping current behavior
Data Source
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AI summary
An apparatus includes a string of series-connected voltage clamp devices (e.g., metal-oxide varistors (MOVs)) coupled to at least one electronic device (e.g., a transistor or other semiconductor device). The apparatus further includes a bypass circuit configured to selectively bypass a subset of the string of series-connected voltage clamp devices to control a level at which a voltage applied to the at least one electronic device is clamped. A control circuit may be configured to cause the bypass circuit to bypass the subset of the string of series-connected voltage clamp devices responsive to a voltage applied to the at least one electronic device. For example, the control circuit may be configured to cause the bypass circuit to bypass the subset of the string of series-connected voltage clamp devices responsive to a magnitude of the voltage applied to the at least one electronic device exceeding a threshold.