Leakage Current Reduction via Voltage Detection and Amplification
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Solution Overview
Problem
Conventional high-frequency leakage current reducing apparatuses face issues with phase inversion and resonance due to delay times and impedance, leading to ineffective noise current reduction, and lack consideration for AC power supply systems, resulting in complex configurations and insufficient noise reduction.
Innovation Solution
A leakage current reducing apparatus with a voltage detection means, input-side filter, and voltage amplifier unit is provided between electric apparatuses, using a main winding and a winding for leakage current detection to generate a reduced leakage current, with a simple configuration that stabilizes operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If a high-frequency amplifier is used to amplify the detected high-frequency leakage current, then the leakage current can be amplified, but phase inversion occurs due to delay times causing the injected current to be in the same phase as the leakage current instead of opposite phase
Solution Approach 1:
The patent inverts the conventional approach by detecting voltage instead of current, and applying voltage instead of current. This voltage-based approach eliminates the phase inversion problem that plagues current-based amplification systems, as the voltage detection and application path does not suffer from the same delay-time-induced phase shifts.
Solution Approach 2:
The patent replaces the mechanical/electrical current amplification system with a voltage-based system. By using voltage detection means and voltage application means instead of current detection coils and current amplifiers, the system avoids resonance issues and phase inversion problems inherent in inductive current-based systems.
2Power
If a high-frequency amplifier is used, then leakage current can be amplified, but resonance occurs due to impedances and inductances causing unnecessary power supply and amplified leakage current
Solution Approach 1:
The patent replaces the resonant-prone current amplification system with a voltage amplification system. The voltage amplifier unit amplifies the detected voltage signal without encountering the resonance issues that arise from the interaction between amplifier output impedance and the inductive reactance of coils and line inductance in current-based systems.
3Reliability
If a control circuit is added to cancel component variations and temperature influences, then noise reduction effectiveness can be improved, but the number of components increases and circuit configuration becomes complicated
Solution Approach 1:
The patent employs a voltage detection means that inherently provides stable detection不受 component variations and temperature influences. The system self-regulates by detecting voltage directly at the point of interest, eliminating the need for additional control circuits to compensate for environmental variations.
4Measurement precision
If conventional current-based leakage current reduction is used, then leakage current can be detected, but the configuration becomes complex and stable operation is difficult to achieve
Solution Approach 1:
The patent substitutes current-based detection with voltage-based detection. The voltage detection means directly measures the voltage associated with leakage current without requiring current coils, amplifiers, and matching circuits, thereby simplifying the overall configuration while maintaining detection precision.
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 apparatus effectively reduces leakage current with a stable operation by detecting and amplifying voltage to cancel out high-frequency leakage currents, reducing noise and simplifying the circuit configuration, while considering AC power supply systems.
Implementation Method 1
The main winding is provided, via the connection line, between the first electric apparatus and the second electric apparatus, so that a leakage current flowing in the connection line is detected, as a detected voltage, by the winding for leakage current detection
Implementation Method 2
The voltage amplifier unit amplifies a voltage outputted from the input-side filter, and outputs the amplified voltage as an output voltage
Implementation Method 3
The voltage application means generates, on the connection line, an application voltage for reducing the leakage current, based on the output voltage
Data Source
AI summary
First windings of a first common mode transformer and second windings of a second common mode transformer are connected in series via connection lines. The windings are connected to an AC power supply via connection lines. The first windings are connected to a three-phase motor via connection lines, a converter, and an inverter. High-frequency leakage currents flowing in the connection lines are detected as a common mode voltage by a winding for common mode voltage detection. An output voltage is inputted via a filter to a voltage amplifier unit that amplifies the output voltage, and the amplified voltage is applied to a winding via a capacitor in substantially a same direction as a direction of the common mode voltage. As a result, leakage currents are reduced by induced voltages on the windings.