Power Conversion Circuit Compensation for Leakage Current
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Solution Overview
Problem
Conventional power conversion circuits face challenges in reliably canceling leakage currents due to switching device delays and noise sensitivity, leading to increased costs and potential malfunctions from direct gate connections.
Innovation Solution
A power conversion circuit with a separate compensation circuit and compensation generator that adjusts charge/discharge timing and voltage slopes to cancel conducted emissions, using a controller with integrated current sources and a delay time setter to generate appropriate cancellation voltages, allowing for flexible compensation of leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a compensation capacitor is connected directly to the gate of the switching device to cancel leakage current, then the leakage current cancellation effect is improved, but the switching device becomes sensitive to noise and may malfunction
Solution Approach 1:
The patent introduces an intermediary circuit between the compensation capacitor and the gate of the switching device. This intermediary circuit includes a series connection of a capacitor and a resistor, which acts as a buffer to isolate the gate from direct connection to the compensation capacitor. The intermediary circuit allows the compensation current to flow while preventing high-frequency noise and voltage spikes from directly affecting the gate, thus resolving the contradiction between achieving effective leakage current cancellation and avoiding noise-induced malfunctions.
2Productivity
If the switching device is switched ON and OFF to perform power conversion, then the power conversion function is achieved, but conducted emissions and leakage currents are generated
Solution Approach 1:
The patent converts the harmful conducted emissions into a beneficial compensation mechanism. By detecting the voltage across the switching device and generating a compensation voltage that mirrors the emitted noise, the system transforms the harmful high-frequency switching noise into a useful cancellation signal. The compensation capacitor discharges in synchronization with the switching device, creating a compensation current that flows through the parasitic capacitance in the opposite direction to the leakage current, thereby canceling the conducted emissions while maintaining power conversion functionality.
3Object-affected harmful factors
If a separate compensation circuit is introduced to cancel leakage current, then the conducted emissions are suppressed, but the circuit complexity increases
Solution Approach 1:
The patent merges the compensation circuit with the existing power conversion circuit by utilizing shared components and integrated control. The compensation capacitor is connected in parallel with the switching device, and the compensation voltage is generated from the same voltage source that drives the power conversion. The control logic for the compensation circuit is integrated with the switching control, allowing both power conversion and noise cancellation to be managed by a unified control mechanism. This merging approach minimizes the additional complexity while achieving effective conducted emissions suppression.
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
This solution enables reliable suppression of conducted emissions and leakage currents, reducing noise impact while avoiding potential malfunctions and simplifying circuit design by allowing for flexible adjustment of compensation currents.
Implementation Method 1
a compensation generator connected to the compensation circuit, the compensation generator charging and discharging the compensation capacitance on the basis of the drive signal so as to generate a cancellation voltage across the compensation capacitor
Data Source
AI summary
In a power conversion circuit in which a grounded capacitor is connected to a main circuit that converts power through operation of a semiconductor switching device, a control IC that supplies a drive signal to the semiconductor switching device generates a cancellation voltage for canceling out a conducted emission that develops across terminals of the grounded capacitor as a result of the operation of the semiconductor switching device by using the drive signal (gate signal) to control a charge/discharge current of a compensation capacitor in a compensation circuit that is externally connected to the main circuit.