High Frequency AC to DC Conversion for Wireless Power Transfer

Key Problem and Market Opportunity

Wireless power transfer (WPT) based on the magnetic resonance and near-field coupling of two loop resonators was reported by Nicola Tesla a century ago. At present, there is a lack of research examining the problems arising from the receiver which also has big impact on the performance of the entire system.
In most of the applications, the AC power output from the receiver is first converted to a DC voltage by a combination of diode and capacitor. However, as capacitor is charged to a value close to the peak of the AC input voltage, the input current is near the peak of the AC input voltage and does not flow continuously. These diode rectifiers draw highly distorted current from the AC source and result in a poor power factor (PF). The energy efficiency and power transfer capability of a poor PF system are relatively low. Additionally, the distorted current has rich harmonic content which may create extra electromagnetic interference (EMI) in neighboring electronic equipment.

Key Advantages of the Technology

The present invention provides a solution for high frequency AC to DC conversion with power factor correction. The distinctive features of this new invention are summarized as follow:
- With the use of a resonance technique, the AC line current is shaped to be sinusoidal and the AC power factor of the converter is near unity.
- The output voltage gain of the converter can be controlled above or below the AC line voltage.
- All the semiconductor devices are operated at a constant frequency which is equal to the frequency of the AC source.
- The control scheme can be realized by simple analog and digital circuits which is favorable for integrated circuit (IC) fabrication.

Potential Product and Services

This invention can be applied in a wide range of WPT system from short range to mid range applications.

Development status and IP Strength

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