Demonstration kits show versatility of AirFuel-resonant power transfer

4th October 2017
Caroline Hayes


Efficient Power Conversion (EPC) has released two demonstration kits, the EPC9127 and EPC9128, that show GaN FETs and ICs can be used in resonant wireless power transfer systems.

Characteristics of eGaN FETs and ICs, such as low output capacitance, low input capacitance, low parasitic inductances, and their small size are used in the demonstration kits to show that they can be used for increasing efficiency in highly resonant, AirFuel Alliance-compatible wireless power transfer systems, says the company.

The EPC9127 wireless power system consists of a source board (transmitter or power amplifier) the EPC9510, a 10W Class 2 AirFuel Alliance-compliant source coil (transmit coil) and a category 3 AirFuel Alliance-compliant receiving device, the EPC9513.

There are four boards in the EPC9128 kit. There is a source board (transmitter or power amplifier) the EPC9509, a Class 3 AirFuel Alliance-compliant source coil (transmit coil), a Category 3 AirFuel Alliance-compliant receiving device, the EPC9513 and a Category 4 AirFuel Alliance-compliant receiving device, the EPC9515.

The two demonstration kits join the company's EPC9120, 33W class 4 and the EPC9121 multi-mode kit capable of operating to either an AirFuel Class 2 standard with a category 3 device or a Qi (A6)/PMA standard with a compatible receiving device to provide a range of wireless power demonstration kits.

The popularity of resonant wireless power transfer is increasing rapidly, explains the company, with end applications evolving quickly from mobile phone battery charging, to powering large surface areas where handheld tablets, laptops, and computers (and, soon TV sets, lamps, and other electrically powered appliances) simultaneously, anywhere on the surface. With the introduction of these demonstration kits, the company says it covers the full range of the AirFuel resonant technology standard.

The kits can simplify the evaluation process of using eGaN FETs and ICs for efficient wireless power transfer. The kits, operating at 6.78MHz (the lowest ISM band) use the high frequency switching capability of EPC gallium nitride (GaN) transistors to facilitate wireless power systems. Efficiency is about 87 per cent from input to the amplifier to the output of the receiver (end-to-end). Future improvements in architecture and GaN IC technology could see this reach 95 per cent, says the company.

The source (amplifier) boards included in these kits are efficient zero voltage switching (ZVS), Class-D amplifiers configured in an optional half-bridge topology (for single-ended configuration) or default full-bridge topology (for differential configuration). They include the gate driver(s), oscillator, and feedback controller for the pre-regulator. This allows for compliance testing operating to the AirFuel standard over a wide load range, says the company. The amplifier boards are available separately as EPC9509 and EPC9510 for evaluation in existing customer systems.

The receiving device boards include the Category 3 EPC9513 (5.0V, 5.0W) and Category 4 EPC9515 (5.0V, 10W) receiving device boards. They are available separately for customers which have their own source boards or for those who want to design wireless power systems powering multiple devices simultaneously.

According to the company, the range of efficient receivers enables developers to design wireless power systems that can be used to power anything from lamps to laptops to tablets, while remaining compatible with cell phone charging.

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