Power Converter EMI Reduction via PWM Phase Hopping
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Solution Overview
Problem
Conventional power converters using switching regulators generate electromagnetic interference (EMI) due to harmonic tones, which existing frequency hopping techniques attempt to mitigate but at the cost of increased switching loss and complexity, requiring multiple ramp generation circuits.
Innovation Solution
Implementing a pulse width modulation (PWM) phase hopping technique that varies the phase of the PWM signal to control the switching device, reducing EMI without the need for frequency hopping and associated inefficiencies, using a single circuit to generate multiple phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency hopping techniques are used to reduce electromagnetic interference, then EMI is reduced, but switching loss increases and device complexity increases
Solution Approach 1:
The patent applies dynamics by making the PWM signal phase variable rather than fixed. The phase hopping mechanism dynamically changes the phase angle of the PWM signal according to a predetermined pattern, transforming the static switching timing into a dynamic, time-varying process. This dynamic phase adjustment spreads the electromagnetic interference energy across different time instances and frequency components, reducing peak EMI levels without requiring frequency changes that would increase switching loss.
Solution Approach 2:
The patent changes the phase parameter of the PWM signal to achieve EMI reduction. By varying the phase angle of the PWM waveform according to a hopping sequence, the timing of switching events is modified without changing the fundamental switching frequency. This parameter change (phase modulation) redistributes the spectral energy of the switching harmonics, reducing electromagnetic interference while maintaining efficient operation at the original frequency.
2Object-affected harmful factors
If frequency hopping techniques are used to reduce electromagnetic interference, then EMI is reduced, but device complexity increases
Solution Approach 1:
The patent applies dynamics by making the PWM signal phase variable rather than fixed. The phase hopping mechanism dynamically changes the phase angle of the PWM signal according to a predetermined pattern, transforming the static switching timing into a dynamic, time-varying process. This dynamic phase adjustment spreads the electromagnetic interference energy across different time instances and frequency components, reducing peak EMI levels without requiring frequency changes that would increase switching loss.
Solution Approach 2:
The patent changes the phase parameter of the PWM signal to achieve EMI reduction. By varying the phase angle of the PWM waveform according to a hopping sequence, the timing of switching events is modified without changing the fundamental switching frequency. This parameter change (phase modulation) redistributes the spectral energy of the switching harmonics, reducing electromagnetic interference while maintaining efficient operation at the original frequency.
3Object-affected harmful factors
If multiple ramp generation circuits are used for frequency hopping, then EMI reduction is achieved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies universality by using a single ramp generation circuit to serve multiple phase hopping functions. Instead of requiring separate ramp circuits for each frequency in a frequency hopping scheme, this invention uses one universal ramp generator that works in conjunction with phase modulation to achieve EMI reduction across all operating conditions. The single circuit generates the necessary timing signals for phase-hopped PWM operation, eliminating the need for multiple specialized circuits.
Solution Approach 2:
The patent applies universality by using a single ramp generation circuit to serve multiple phase hopping functions. Instead of requiring separate ramp circuits for each frequency in a frequency hopping scheme, this invention uses one universal ramp generator that works in conjunction with phase modulation to achieve EMI reduction across all operating conditions. The single circuit generates the necessary timing signals for phase-hopped PWM operation, eliminating the need for multiple specialized circuits.
Data Source
AI summary
Methods and apparatus for reducing electromagnetic interference in a power converter using phase hopping in conjunction with pulse width modulation are disclosed. An example power converter includes an input voltage to, when a control switching device receives a first voltage, increase an output voltage; and when the control switching device receives a second voltage, decrease the output voltage. The example power converter further includes a phase hopping generator to generate a phase varying signal corresponding to two or more phases, the phase varying signal corresponding to a reference voltage; and output the phase varying signal to control the control switching device.