Effect of Hybrid Modulation on Performance of Wireless Battery Charger Operating in CC/CV Mode

Suppression of Radiated Emissions from Inductive-Resonant Wireless Power Transfer Systems by Using Spread-Spectrum Technique

“…The coefficient can be defined as a difference between the maximum emission levels (in frequency domain, expressed, e.g., in dBμV or dBμA/m) of a WPT system with and without spread spectrum. As it is shown in [16] or [22] for conducted emissions, the spectrum spreading effect and the peak emissions level reduction associated with it depend on periodic SFM parameters, such as Δfpeak, fm and modulation waveform.…”

“…As a traditional way for conducted EMI reduction-input EMI filtering-adds noticeable cost, size and weight to the inductive-resonant WPT system, a spread-spectrum technique based on modulation of WPT system inverter switching frequency has been applied to inductive-resonant WPT systems [16][17][18][19][20][21][22]. A typical approach for the reduction of radiated emissions is shielding, but shields are expensive and they increase the size and cost of the WPT systems.…”

“…There are many papers related to the reduction of conducted emissions using a spread-spectrum approach in WPT systems [16][17][18][19]21,22], but there is only one paper [20] about the suppression of radiated emissions using the approach in WPT systems. As shown in [20], fundamental components of the radiated emissions of the inductive-resonant WPT system can be reduced by up to 8.3 dB when the spread-spectrum technique based on the random modulation of inverter-switching frequency is used.…”

Thorough Study of Multi-Switching-Frequency-Based Spread-Spectrum Technique for Suppression of Conducted Emissions from Wireless Battery Chargers

“…In order to reduce size and cost of the passive filters or even eliminate them, an interesting and useful approach called the spread spectrum was adapted from communication engineering and applied to conventional switch-mode power converters last decade [10]. Recently, the approach was also applied to inductive-resonant wireless battery chargers for reducing conducted and radiated emissions [11][12][13][14][15][16]. Spreading the spectrum of the conducted emissions of the wireless chargers can be achieved by different approaches, such as switching frequency modulation [5,13,16], simultaneous switching frequency and duty cycle modulation (also known as the hybrid modulation) [11], multi-switching frequency technique [12] or even multi-frequency-multi-duty-cycle approach [15].…”

“…Recently, the approach was also applied to inductive-resonant wireless battery chargers for reducing conducted and radiated emissions [11][12][13][14][15][16]. Spreading the spectrum of the conducted emissions of the wireless chargers can be achieved by different approaches, such as switching frequency modulation [5,13,16], simultaneous switching frequency and duty cycle modulation (also known as the hybrid modulation) [11], multi-switching frequency technique [12] or even multi-frequency-multi-duty-cycle approach [15]. In contrast with the passive or active filters, the spread spectrum approach does not increase the size, weight or cost of inductive-resonant WPT systems because it can be implemented by using, for instance, a microcontroller with a suitable code.…”