Gate Resistance Control for Common Mode Voltage Reduction
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Solution Overview
Problem
Common mode voltage generated by capacitive coupling in electric drive motors of green vehicles causes electromagnetic noise, affecting radio reception and inducing electrical corrosion, leading to poor driving force transmission and controller interference.
Innovation Solution
An apparatus and method that detect common mode voltage between a drive shaft and motor frame, using a gate resistance unit and controller to adjust resistance based on detected voltage and reference values, with a contact unit and filter to measure high-frequency components, and switching elements to manage resistance levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-voltage and high-frequency switching is performed for power conversion, then power conversion efficiency is improved, but common mode noise and electromagnetic wave noise are generated
Solution Approach 1:
A common mode voltage detecting unit is introduced as an intermediary to monitor the common mode voltage between the drive shaft and frame. Based on the detected voltage level, a gate resistance adjusting unit dynamically adjusts the gate resistance value to suppress common mode noise while maintaining power conversion efficiency. This intermediary detection and adjustment mechanism resolves the contradiction by providing real-time control.
Solution Approach 2:
The gate resistance value is made dynamic rather than fixed. The gate resistance adjusting unit changes the resistance value based on the detected common mode voltage level, allowing the system to adaptively suppress noise during high-frequency switching operations while maintaining efficiency. This dynamic adjustment resolves the contradiction between productivity and noise generation.
2Reliability
If parasitic capacitance is present between stator and rotor, between rotor and drive shaft, and between motor body and bearing, then capacitive coupling occurs, but common mode voltage is generated causing electromagnetic noise and bearing corrosion
Solution Approach 1:
A feedback mechanism is implemented where the common mode voltage detecting unit continuously monitors the voltage between drive shaft and frame. The detected voltage level feeds back to the gate resistance adjusting unit, which dynamically adjusts the resistance to suppress common mode voltage. This feedback loop prevents electrical corrosion while maintaining reliable electrical connections.
Solution Approach 2:
The harmful common mode voltage is extracted and suppressed by dynamically adjusting the gate resistance. By taking out the problematic voltage component through resistance adjustment, the system protects bearings from electrical corrosion while maintaining the necessary parasitic capacitance for reliable electrical connections.
3Object-generated harmful factors
If common mode voltage is reduced by adjusting gate resistance, then electromagnetic noise is minimized, but additional control complexity is introduced
Solution Approach 1:
The controller is designed to perform multiple functions: it detects common mode voltage, determines appropriate resistance values, and adjusts gate resistance all in one integrated unit. This multi-functionality reduces control system complexity while effectively minimizing electromagnetic noise through coordinated control actions.
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
Effectively reduces common mode voltage, minimizing electromagnetic noise and bearing abrasion, thereby improving driving performance and reducing interference with vehicle controllers.
Implementation Method 1
the capacitive coupling, attributed to the parasitic capacitance of high-voltage parts, generates common mode voltages
Implementation Method 2
a gate resistance unit of a power module connected to the drive motor; and a controller configured to adjust a magnitude of resistance of the gate resistance unit
Data Source
AI summary
An apparatus and a method for that reduce a common mode voltage are provided. The apparatus includes a detecting unit that is configured to detect a common mode voltage between a drive shaft and a frame of a drive motor. In addition, a gate resistance unit of a power module is connected to the drive motor. A controller is configured to adjust a magnitude of resistance of the gate resistance unit, based on a magnitude of the detected common-mode voltage and a magnitude of a predetermined reference voltage.