PWM Control Unit Noise Reduction via Phase Angle Adjustment
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Solution Overview
Problem
Existing PWM control systems for inverters in motor vehicles fail to effectively reduce noise when PWM frequency changes, often leading to noise amplification due to deviations in phase opposition of forces in electrical machines.
Innovation Solution
A control unit with a noise reduction device that adjusts the phase angle of the opposing signal based on a predefined PWM frequency and speed, using lookup tables to determine phase deviations and offsets, ensuring phase opposition and efficient noise suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fixed PWM frequency is used for noise reduction, then noise reduction is effective at that frequency, but noise reduction performance deteriorates when PWM frequency changes
Solution Approach 1:
The patent implements dynamic adaptation of the opposing signal parameters (phase angle and frequency) based on the actual PWM frequency. The control unit continuously monitors the PWM frequency and adjusts the opposing signal characteristics in real-time, transforming the static noise reduction approach into a dynamic one that maintains effectiveness across varying operating conditions.
Solution Approach 2:
The patent changes the parameters of the opposing signal (phase angle and frequency) according to the PWM frequency variations. By dynamically adjusting these parameters, the system maintains the opposing signal's ability to counteract electromagnetic forces and reduce noise across different PWM frequencies, resolving the contradiction between fixed-frequency effectiveness and frequency adaptability.
2Loss of energy
If PWM frequency is optimized for minimal losses, then energy efficiency is improved, but noise reduction performance deteriorates
Solution Approach 1:
The patent dynamically adjusts the opposing signal parameters (phase angle and frequency) based on the PWM frequency that is already optimized for minimal losses. This allows the noise reduction system to adapt to the operating point without requiring a compromise in PWM frequency selection, enabling simultaneous optimization of both energy efficiency and noise reduction.
Solution Approach 2:
The control unit monitors the actual PWM frequency and uses this information to adjust the opposing signal parameters accordingly. This feedback mechanism ensures that the noise reduction system remains effective regardless of the PWM frequency selected for optimal energy efficiency, allowing both objectives to be achieved simultaneously.
Data Source
AI summary
A control unit generates pulse width modulation (PWM) pulses for an inverter. The control unit has a noise reducer configured to generate an opposing signal for active noise reduction. The noise reducer is configured to set a phase angle of the opposing signal based upon a predefined PWM frequency.