SMPS Controller Jitter Compensation for EMI Reduction
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Solution Overview
Problem
Existing SMPS technologies face challenges in effectively managing electromagnetic interference (EMI) and audio noise due to fixed switching frequencies, with current jittering methods being inadequate for variable operating points and output power control.
Innovation Solution
A controller for SMPS that uses a frequency jitter unit and a further jitter unit to multiply input signals, ensuring that the jitter applied to the frequency and other variables vary in proportion, allowing for relative compensation and maintaining constant output power across different operating points, thereby reducing EMI and audio noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency jittering is applied to reduce EMI peaks and audio noise, then EMI interference and audible noise are reduced, but output power varies due to frequency changes
Solution Approach 1:
The patent applies preliminary anti-action by introducing a compensation signal that anticipates and counteracts the power variation caused by frequency jittering. The compensation signal is generated based on the jittering signal and added to the control signal, creating a preemptive correction that prevents output power deviation before it occurs.
Solution Approach 2:
The patent implements feedback by using the jittering signal itself as the basis for generating the compensation signal. The compensation mechanism continuously monitors the frequency jittering and adjusts the control signal in real-time to maintain constant output power, creating a closed-loop control system.
2Object-affected harmful factors
If frequency jittering is applied to smear out EMI peaks, then electromagnetic interference is reduced, but control complexity increases due to bandwidth limitations
Solution Approach 1:
The patent uses an intermediary approach by introducing a compensation signal as a mediator between the jittering signal and the control signal. This compensation signal acts as an intermediate element that translates the jittering information into appropriate control adjustments, simplifying the overall control architecture.
3Object-affected harmful factors
If frequency jittering is applied to spread audible noise, then perceived noise level is reduced, but output power control becomes difficult at variable operating points
Solution Approach 1:
The patent achieves universality by designing a compensation mechanism that works across multiple operating conditions and frequencies. The compensation signal generation method is adaptable to different jittering frequencies and amplitudes, making the solution universally applicable to various operating points and power levels.
Data Source
AI summary
A controller for an SMPS is disclosed. The controller applies a frequency jitter to the SMPS to reduce Electromagnetic Interference (EMI) and/or audible noise. A second input variable is multiplied by a correlated jitter signal, in order to compensate the output power for the frequency jitter. A corresponding method is also disclosed. Since the jitter compensation occurs within the controller, the method is particularly suitable for controllers operating under different control modes for different output powers (or other output criteria). The multiplicative compensation is applicable across a wide range of converter types.