Inverter Circuit Overcurrent Protection via Flip-Flop Signal Inversion
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Solution Overview
Problem
Existing inverter circuits for X-ray radiation devices fail to provide timely and efficient protection against overcurrents, which can damage semiconductor switching elements, and require complex circuits with additional components to manage overcurrent protection effectively.
Innovation Solution
An inverter circuit design that includes semiconductor switching elements, a transformer, an electric current detector, a pulse generator circuit, a flip-flop circuit, an electric current bypass switch, and a gate signal generator circuit to quickly interrupt and protect the switching elements from overcurrents, allowing for automatic return to normal operation once the overcurrent is eliminated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an operational amplifier is provided between the electric current detection circuit and the flip-flop circuit, then the overcurrent detection function is implemented, but the start of protection of the IGBT is delayed after the detection of an overcurrent
Solution Approach 1:
The patent removes the operational amplifier from the signal path between the overcurrent detection circuit and the flip-flop circuit. By extracting this component, the signal transmission path is shortened and simplified, eliminating the delay caused by the operational amplifier's processing time while maintaining the overcurrent protection function through direct coupling of the detection circuit to the flip-flop circuit.
Solution Approach 2:
The patent implements a direct connection path that allows the overcurrent detection signal to skip the operational amplifier stage and reach the flip-flop circuit immediately. This rushing through of the detection signal ensures that protection action begins without the time delay that would otherwise be introduced by the operational amplifier's signal processing.
2Ease of operation
If a photocoupler is mounted on the subsequent stage of an AND element, then the gate signal generation is implemented, but there is need for a circuit that reliably provides an electric current enough to drive the photocoupler, resulting in an increase in the number of components and a complicated circuit
Solution Approach 1:
The patent employs a pulse generator circuit that serves multiple functions: it generates the periodic pulse signals needed for gate drive, provides sufficient current to drive the photocoupler directly, and integrates these functions into a single circuit block. This multi-functional approach eliminates the need for separate current provision circuits and reduces overall circuit complexity while maintaining ease of gate signal generation.
Solution Approach 2:
The patent merges the pulse generation function and the current provision function into a single integrated pulse generator circuit. By combining these functions, the circuit that reliably provides electric current to drive the photocoupler is integrated with the pulse generation logic, reducing the number of discrete components and simplifying the overall circuit architecture.
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 enables rapid protection of semiconductor switching elements from overcurrents, maintaining inverter operation during micro discharges and allowing for automatic recovery, reducing the need for complex circuitry and additional components.
Implementation Method 1
The transformer 107 boosts a voltage from the voltage type bridge inverter 102, and outputs the voltage to the bridge rectifier circuit 114
Implementation Method 2
The bridge rectifier circuit 114 full-wave-rectifies and smooths the alternating voltage from the secondary wire of the transformer 107
Data Source
AI summary
An inverter circuit of an embodiment includes a plurality of semiconductor switching elements constituting a bridge circuit; a transformer connected to the output end of the bridge circuit; an electric current detector that detects whether an electric current carried through at least one of the switching elements exceeds a predetermined value; a pulse generator circuit that transmits a periodic pulse signal; a flip-flop circuit connected to the detector and the pulse generator circuit; a field effect transistor (FET) turned on or off by a signal from the flip-flop circuit; and a gate signal generator circuit connected to the FET and the bridge circuit. The flip-flop circuit inverts an output signal by a detection signal of the detector and interrupts the output of the bridge circuit. The gate signal generator circuit switches the switching element at the diagonal position of the bridge circuit based on a signal from the FET.