Power Supply Current Limiter Self-Test Circuit
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Solution Overview
Problem
Existing power supplies lack a method to easily and reliably test the functionality of current-limiting circuitry, and mechanical torque limiters are unreliable, heavy, and costly, with no straightforward way to verify their functionality in the field.
Innovation Solution
A power supply system with a current limiter, current sensor, and test circuit that allows for self-testing of current-limiting functionality by temporarily changing the current and using feedback signals to adjust the current output, and includes a torque sensor to measure and adjust torque output, enabling verification of operational integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical torque limiters are used to limit torque output, then torque limiting functionality is achieved, but the system becomes unreliable, heavy, and costly with difficult field verification
Solution Approach 1:
The patent replaces mechanical torque limiters with an electrical current-limiting circuit that controls motor current. The current limiter (21) with feedback from current sensor (28) electronically limits current to the motor (23), thereby limiting torque without mechanical components. This substitution eliminates the weight, complexity, and reliability issues of mechanical limiters while enabling easy field verification through the self-test circuit.
Solution Approach 2:
The patent implements a self-test circuit (24) that automatically verifies the current-limiting functionality without external equipment. The test circuit temporarily changes the current to test levels and uses feedback signals to verify the current limiter properly adjusts, allowing the system to self-verify its torque-limiting capability in the field without requiring external probes or equipment.
2Reliability
If external testing equipment is used to verify current-limiting functionality, then accurate testing is possible, but the testing process becomes complex and requires additional equipment
Solution Approach 1:
The patent implements a self-test circuit (24) that automatically verifies the current-limiting functionality without external equipment. The test circuit temporarily changes the current to test levels and uses feedback signals to verify the current limiter properly adjusts, allowing the system to self-verify its operation. This eliminates the need for external voltage and current probes, reducing testing complexity to zero additional equipment.
Solution Approach 2:
The test circuit (24) integrates multiple functions into a single onboard component: it generates test current levels, monitors feedback signals, verifies current limiter response, and confirms operational integrity. This multi-functional integration allows the same circuitry to both operate the motor and verify its own functionality, eliminating the need for separate external testing equipment.
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
Enables easy testing and verification of current-limiting functionality, providing a fault-tolerant and reliable power supply that limits torque effectively, reducing the need for external testing equipment and improving the reliability and cost-effectiveness over mechanical torque limiters.
Implementation Method 1
The current sensor (28) may include at least one resistor (40,41), and may also produce more than one feedback signal (30, 31)
Implementation Method 2
The current limiter may include a differential amplifier (45) which is configured to measure the difference between two feedback signals (30, 31)
Data Source
AI summary
A power supply (20) for providing a desired current to an electric load (23) broadly comprises: a current limiter (21) for providing a desired current; a current sensor (28) for determining the actual current supplied by the current limiter and providing a feedback signal (30, 31) to the current limiter for causing the current limiter to reduce the error between the desired and the actual currents; and a test circuit (24) for temporarily changing the actual current sensed by the current sensor to a level different from the desired current for causing the current limiter to adjust the magnitude of the current provided thereby; whereby the operation of the power supply may be tested. The invention also provides an improved method of operating such a power supply.