Inductive Load Switching Circuit With Low-Heat Voltage Clamping
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Solution Overview
Problem
Existing semiconductor devices with active clamping circuits face challenges in improving clamp resistance while maintaining durability for high voltage applications, as lower clamp voltages lead to increased risk of element destruction due to high heat generation during energy handling.
Innovation Solution
A semiconductor device design that includes a switching element, a drive circuit, an extracting circuit, and a voltage control circuit, where the voltage control circuit clamps the voltage drop at the connection point between the switching element and the inductive load to a predetermined voltage, reducing clamp resistance and enhancing durability by using a voltage-controlled MOS transistor to manage voltage drops effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an active clamping circuit is used to clamp voltage during switching transitions, then voltage control is improved, but heat generation increases and element destruction risk increases
Solution Approach 1:
The patent extracts the essential clamping function from a complex active clamping circuit and implements it through a simple voltage-controlled MOS transistor that activates only during the critical switching transition period. This selective extraction of the clamping function reduces continuous heat generation while maintaining voltage control when needed.
Solution Approach 2:
The patent uses a dynamic approach by making the clamping transistor conductivity variable through voltage control. The transistor transitions between off-state, partial conduction, and full conduction based on the switching timing, allowing adaptive heat management while maintaining voltage control during critical periods.
2Loss of energy
If clamp voltage is reduced to improve clamp resistance, then energy handling efficiency improves, but element destruction risk increases due to insufficient voltage protection
Solution Approach 1:
The patent applies periodic action by activating the clamping function only during the specific time period when the switching element transitions from on to off state. The voltage-controlled transistor is turned on temporarily during this critical interval and then turned off, providing protection only when needed while allowing normal operation otherwise, thus improving energy efficiency without sacrificing reliability.
3Reliability
If an active clamping circuit is implemented, then voltage clamping capability is improved, but device complexity increases
Solution Approach 1:
The patent extracts only the essential clamping function from a complex active clamping circuit and implements it through a simple voltage-controlled MOS transistor with basic control logic. This selective extraction eliminates unnecessary circuit components while retaining the core voltage clamping capability during switching transitions.
Solution Approach 2:
The patent changes the control parameter from complex multi-signal control in active clamping circuits to simple voltage-level control of a MOS transistor. By controlling the transistor's conductivity through voltage adjustments rather than complex circuit arrangements, the patent achieves voltage clamping with significantly reduced device complexity.
Data Source
AI summary
A semiconductor device for operating an inductive load, including: a switching element having a control terminal, a low potential terminal and a high potential terminal; a drive circuit configured to apply a control voltage to the control terminal of the switching element to switching-drive the switching element, and operate the inductive load connected to the switching element; an extracting circuit configured to extract control terminal charges from the control terminal of the switching element when the switching element makes a transition from an on state to an off state; and a voltage control circuit connected to a connection point between the low potential terminal of the switching element and the inductive load, the voltage control circuit being configured to clamp a drop in a voltage at the connection point to a predetermined voltage while the extracting circuit is extracting the control terminal charges.