Electric Power Converter Ripple Attenuation via Variable Phase PWM
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Solution Overview
Problem
Existing electric power converter apparatuses using switching elements fail to reduce the amplitude of high-frequency ripple current frequency components, leading to substantial electrical noise that interferes with radio reception.
Innovation Solution
The apparatus employs multiple electric power converter circuits with control circuitry that generates PWM signals of identical frequency but differing phases to minimize the amplitude of specific ripple current frequency components, utilizing a data map to determine optimal phase differences based on duty ratios and frequency analysis to reduce noise effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple electric power converter circuits are used with phase-dispersed PWM signals, then the amplitude of ripple current is reduced, but the amplitude of ripple current frequency components (harmonics) remains high
Solution Approach 1:
The patent changes the phase difference parameter between PWM signals from fixed even dispersal (e.g., 120 degrees for three circuits) to variable phase differences that are specifically optimized to minimize ripple current frequency components. The control circuit adjusts the phase difference based on the switching frequency and duty ratio to achieve minimal amplitude of frequency components within a predetermined frequency range.
Solution Approach 2:
The patent implements a control circuit that monitors the switching frequency and duty ratio of the PWM signals, and dynamically adjusts the phase difference between PWM signals fed to different electric power converter circuits. This feedback mechanism ensures that the phase difference is continuously optimized to minimize ripple current frequency components under varying operating conditions.
2Device complexity
If the phase difference between PWM signals is fixed for even dispersal, then the control system is simple, but the amplitude of specific frequency components cannot be minimized
Solution Approach 1:
The patent transitions from a static phase difference configuration to a dynamic one where the phase difference is continuously adjusted based on operating conditions. The control circuit calculates and updates the phase difference in real-time according to the switching frequency and duty ratio, enabling the system to adaptively minimize ripple current frequency components while maintaining manageable complexity through algorithmic control.
3Power
If PWM duty ratio varies, then the output power is adjustable, but the optimal phase difference for minimizing frequency components changes
Solution Approach 1:
The patent implements dynamic adjustment of phase difference in response to changes in PWM duty ratio. When the duty ratio changes to adjust output power, the control circuit simultaneously updates the phase difference between PWM signals to the optimal value that minimizes ripple current frequency components for the new operating point, ensuring noise suppression is maintained across the full power range.
Solution Approach 2:
The control circuit continuously monitors the duty ratio of PWM signals and uses this feedback to adjust the phase difference accordingly. This ensures that as the output power is varied through duty ratio changes, the phase difference is automatically optimized to minimize frequency components, maintaining low electrical noise across all power levels.
Data Source
AI summary
An electric power converter apparatus incorporates a plurality of electric power converter circuits having respective output terminals connected in common, with output power being produced from the common output terminals. Each converter circuit uses an identical switching frequency, in executing power conversion based on PWM control of switching by a plurality of switching elements. The switching operations of the respective converter circuits mutually differ in phase, by an amount determined in accordance with the currently applied PWM duty ratio. The phase difference value is predetermined for minimizing the amplitude of specific harmonic frequency components of a ripple current component in the output current from the apparatus.