AC Freewheeling Circuit for Inductive Load Overvoltage Control
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Solution Overview
Problem
Existing power supply systems with inductive loads face overvoltage conditions when the power source is switched OFF, leading to potential damage and safety hazards due to the inability of current paths to instantly decay, and existing solutions like TVS diodes, resistors, and controlled switches suffer from impracticality, additional losses, or oscillations.
Innovation Solution
Implementing a freewheeling circuit with a switch controller that monitors load voltage and current thresholds to activate or deactivate a freewheeling path using a switch and electrical damping, preventing overvoltage by allowing current decay through a resistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a freewheeling diode is coupled across DC powered loads, then a decay path for current is provided, but it shorts the power source when used with AC power
Solution Approach 1:
The patent employs a synchronous switch that dynamically changes state based on the AC power cycle. The switch is closed during the active phase to provide current decay path and opened during the reverse phase to prevent power source shorting. This dynamic switching resolves the contradiction between providing continuous current decay path and preventing harmful shorting of the AC power source.
Solution Approach 2:
The control system monitors the state of the inductive load and the AC power cycle phase to determine when to activate or deactivate the freewheeling path. This feedback mechanism ensures the synchronous switch operates at the correct timing, providing current decay path only when safe and preventing power source shorting during reverse voltage phases.
2Reliability
If additional synchronous driven switching elements are used, then controlled freewheeling is achieved, but cost and system complexity increase
Solution Approach 1:
The synchronous switch serves multiple functions: it acts as the main power switching element, provides controlled freewheeling path, and prevents power source shorting. By making the switch multi-functional, the patent eliminates the need for separate dedicated freewheeling diodes or additional switching elements, thereby reducing system complexity while maintaining controlled freewheeling capability.
Solution Approach 2:
The patent merges the freewheeling function with the main power switching element. The synchronous switch is designed to handle both the primary power switching and the freewheeling operations, combining multiple functions into a single component. This integration reduces the total number of components and simplifies the overall system architecture.
3Stability of the object's composition
If a resistor with small resistance value is used, then good signal shaping is achieved, but unwanted high losses occur
Solution Approach 1:
Instead of using a fixed low-value resistor that causes continuous power losses, the patent employs a dynamic switching mechanism that activates the freewheeling path only when needed during the AC cycle. This dynamic approach provides effective current decay and signal shaping while minimizing energy losses by keeping the low-impedance path disconnected during non-operational phases.
Solution Approach 2:
The freewheeling path is activated periodically in synchronization with the AC power cycle rather than continuously. The synchronous switch closes during specific phases when current decay is needed and opens during other phases, providing periodic action that achieves signal shaping while reducing average power losses compared to continuous resistor-based solutions.
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 freewheeling circuit effectively prevents overvoltage conditions by ensuring load voltage remains within safe limits, reducing component damage and safety risks while minimizing losses and oscillations.
Implementation Method 1
allowing current decay through a resistor
Data Source
AI summary
This disclosure describes systems, methods, and apparatuses for preventing over-voltage conditions, the method comprising: monitoring, using a freewheeling circuit, a load voltage across a load, wherein the load is configured to receive power from a power supply; monitoring a freewheeling current in the freewheeling circuit; and controlling a state of the freewheeling circuit, based at least in part on one or more of comparing the load voltage to a voltage threshold, and comparing the freewheeling current to at least one current threshold.