In-Vehicle Inverter Noise Reduction Circuit Design
Solution Overview
Problem
In-vehicle inverter devices face challenges in suppressing noise leakage across a wide frequency band due to parasitic capacitance and inductance, which can lead to increased noise amplitude and resonance issues, affecting the versatility and performance of inverter circuits.
Innovation Solution
The in-vehicle inverter device incorporates a noise reduction circuit with a common mode choke coil, input-side and output-side capacitors and resistors, and two filter circuits to effectively reduce common mode and normal mode noise, thereby controlling leakage noise in a wide frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the frequency band of noise suppression is widened to improve versatility, then the device can be applied to various types of vehicles, but noise amplitude near resonance frequency increases due to unintended resonance circuits formed by parasitic capacitance
Solution Approach 1:
The patent introduces a damping resistor as an intermediary element connected in parallel with the parasitic capacitance. This resistor acts as a mediator that dissipates the resonant energy through resistive damping, preventing the amplification of noise at resonance frequencies while allowing the noise suppression frequency band to remain wide for versatility across different vehicle types.
2Object-generated harmful factors
If a common mode choke coil is used to reduce common mode and normal mode noise, then noise reduction is achieved, but unintended resonance circuits are formed due to parasitic capacitance and inductance
Solution Approach 1:
The patent converts the harmful effect of parasitic capacitance and inductance forming unintended resonance circuits into a beneficial configuration by intentionally designing a damping circuit. The damping resistor is specifically placed to exploit the resonant phenomenon, converting the potentially harmful resonance into a controlled energy dissipation mechanism that stabilizes the overall system response.
3Power
If switching elements perform switching actions to convert DC power to AC power, then power conversion is achieved, but noise is generated that can leak out and affect other in-vehicle devices
Solution Approach 1:
The patent extracts the noise component from the power conversion system by introducing a dedicated noise reduction circuit. The common mode choke coil and damping resistor are specifically designed to extract and dissipate the noise generated by switching element operations, separating the noise pathway from the power conversion pathway to prevent noise leakage to other in-vehicle devices.
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 configuration reduces leakage noise across a wide frequency range, including resonance frequencies, enhancing the device's ability to suppress noise and prevent malfunctions, ensuring reliable AC power conversion and reducing adverse effects on connected in-vehicle devices.
Implementation Method 1
a common mode choke coil configured to reduce common mode noise and normal mode noise contained in the DC power
Implementation Method 2
The first filter circuit and the second filter circuit are configured to reduce leakage noise generated in the inverter circuit
Data Source
AI summary
An in-vehicle inverter device includes a noise reduction circuit, which has a common mode choke coil configured to reduce common mode noise and normal mode noise contained in DC power, and an inverter circuit, which receives the DC power in which the noise has been reduced. The noise reduction circuit includes: an input-side capacitor and an input-side resistor provided on the input side of the choke coil; an output-side capacitor and an output-side resistor provided on the output side of the choke coil; a first filter circuit that includes the choke coil, the input-side capacitor, and the input-side resistor; and a second filter circuit that includes the choke coil, the output-side capacitor, and the output-side resistor. The first and the second filter circuits reduce leakage noise generated in the inverter circuit.