Power Supply Clamp Circuit for Inductive Load Surge Protection
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Solution Overview
Problem
Existing power supply devices face challenges in effectively clamping negative voltage surges from counter electromotive forces in inductive loads without requiring high clamp voltages, which can lead to semiconductor element breakdown and increased costs due to stringent component specifications.
Innovation Solution
A power supply device with a clamp circuit that uses a switch semiconductor element, operation voltage setting diodes, and control semiconductor elements to clamp negative voltage surges with reference to ground potential, reducing the clamp voltage to approximately 5V and increasing clamp resistance, thereby preventing semiconductor element malfunction and cost inefficiencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a clamp circuit is designed to clamp negative voltage surges with reference to power supply voltage Vcc, then the output semiconductor element Q1 can be protected from breakdown, but the clamp voltage must be set very high (almost as high as the highest rated voltage of Q1), which increases device complexity and cost
Solution Approach 1:
The patent introduces a ground voltage line as an intermediary reference potential between the power supply voltage Vcc and the semiconductor element gate. By referencing the clamp circuit to ground voltage instead of Vcc, the circuit achieves effective protection while using a lower, more manageable clamp voltage level, thus reducing complexity without sacrificing reliability
Solution Approach 2:
The patent changes the reference voltage parameter from power supply voltage Vcc to ground voltage (0V). This parameter change allows the clamp circuit to operate at a lower voltage level (approximately 5V or less) while still providing adequate protection, thereby reducing the stringency of component specifications and overall device complexity
2Reliability
If the clamp voltage is set high to protect the output semiconductor element Q1, then breakdown can be prevented, but the clamp resistance decreases, reducing the ability to handle energy from voltage surges
Solution Approach 1:
The patent changes the reference voltage parameter from high power supply voltage Vcc to low ground voltage (0V). This parameter change enables the clamp circuit to maintain high clamp resistance while providing adequate protection, because the clamp voltage is now measured from ground level rather than from the high Vcc level, allowing the circuit to handle more energy from voltage surges
3Reliability
If high clamp voltage is used to protect the output semiconductor element, then breakdown protection is achieved, but component specifications become more stringent, increasing manufacturing cost
Solution Approach 1:
The patent changes the reference voltage parameter from power supply voltage Vcc to ground voltage (0V), which fundamentally alters the absolute voltage levels required for protection. This parameter change relaxes component specification requirements because standard components with lower voltage ratings can be used, making the device easier and less costly to manufacture while maintaining adequate protection levels
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 clamps negative voltage surges at a low voltage, reducing the risk of semiconductor element breakdown and minimizing the variation in clamp voltage, while increasing the clamp resistance to handle more energy, thus enhancing the protection and efficiency of the power supply device.
Implementation Method 1
an operation voltage setting diode which determines an ON-operation voltage of the switch semiconductor element with reference to an operation reference voltage of the output semiconductor element
Data Source
AI summary
A power supply device includes an output semiconductor element and a clamp circuit. The output semiconductor element is provided between a power supply line and an output terminal. The output semiconductor element is driven and switched so as to supply electric power to an inductive load connected to the output terminal. The clamp circuit clamps a voltage applied between the power supply line and the output terminal due to a counter electromotive force generated in the inductive load when the output semiconductor element turns OFF, with reference to an operation reference voltage of the output semiconductor element. Thus, it is possible to provide a power supply device including a clamp circuit which can effectively clamp a negative voltage surge derived from a counter electromotive force generated in an inductive load, at a low clamp voltage.