Efficient Power Conversion Corp (EPC) of El Segundo, CA, USA, which makes enhancement-mode gallium nitride on silicon (eGaN) power field-effect transistors (FETs) for power management applications, has announced the availability of a complete demonstration wireless power transfer kit. The 40V (EPC9111) or 100V (EPC9112) wireless kits have three components: source (or amplifier) board; Class 3 A4WP-compliant source (or transmit) coil; and Category 3 A4WP-compliant device (or receiving) board including coil.
The system is capable of delivering up to 35W into a DC load while operating at 6.78MHz (the lowest ISM band). The demonstration kit is intended to simplify the evaluation process of using eGaN FETs for highly efficient wireless power transfer. The EPC9111 and EPC9112 utilize the high-frequency switching capability of EPC’s GaN transistors to facilitate wireless power systems with greater than 75% efficiency.
Value of eGaN FETs in wireless power transfer systems
The requirements of wireless energy transfer systems include high efficiency, low profile, robustness to changing operating conditions and, in some cases, light weight. These requirements translate into designs that need to be efficient and able to operate at high switching speeds without a bulky heat-sink, says EPC. The design must also be able to operate over a wide range of coupling and load variations. The fast switching capability of eGaN FETs is suitable for highly resonant power transfer applications, says the firm.
The popularity of highly resonant wireless power transfer is growing rapidly, particularly for applications targeting portable device charging. The end applications are varied and evolving quickly, from mobile device charging to life-extending medical implementations and safety-critical hazardous environments, says EPC.
Source (amplifier) board
The source board is a highly efficient, A4WP-compliant, zero voltage switching (ZVS) Class-D amplifier featuring either the 40V EPC2014 (EPC9111) or 100V EPC2007 (EPC9112) eGaN FET.
The source board is configured in an optional half-bridge topology (for single-ended configuration) or default full-bridge topology (for differential configuration), and includes the gate driver(s) and oscillator that ensure operation of the system at 6.78MHz.
The amplifier boards are available separately as EPC9506 and EPC9507 for evaluation in existing customer systems.
Source (transmit) coil
The source coil, as well as the device coil, are Rezence (A4WP)-compliant and have been pre-tuned to operate at 6.78MHz. The source coil is class 3 and the device coil is category 3 compliant.
Device (receiving) board including coil
The device board includes a high-frequency Schottky diode based full-bridge rectifier and output filter to deliver a filtered unregulated DC voltage. The device board comes equipped with two LEDs, one to indicate that the power is being received and a second LED that indicates that the output voltage has reached the maximum and is above 37V. The device board can also be configured as a half-bridge rectifier that allows for double output voltage operation.
The EPC9111 and EPC9112 wireless power transfer demonstration systems are priced at $895 each and are available from Digi-Key.
