EPC EPC9129 Manuale di avvio rapido - Pagina 2

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QUICK START GUIDE

DESCRIPTION

The EPC9129 wireless power demonstration system is a high efficiency,

AirFuel

Alliance compatible, Zero Voltage Switching (ZVS), voltage

mode class-D wireless power transfer demonstration kit capable of

delivering up to 33 W into a transmit coil while operating at 6.78 MHz

(Lowest ISM band). The purpose of this demonstration system is to

simplify the evaluation process of wireless power technology using

eGaN® FETs.

The EPC9129 wireless power system is comprised of the four boards

(shown in figure 1), namely:

1) A Source Board (Transmitter or Power Amplifier) EPC9512

2) A Class 4 AirFuel compliant Source Coil (Transmit Coil)

3) A Category 3 AirFuel Alliance compliant Receive Device EPC9513

4) A Category 5 AirFuel Alliance compliant Receive Device EPC9514

The amplifier board (EPC9512) features the enhancement-mode,

100 V rated EPC8010 eGaN FET as the main power stage in a dual half

bridge configuration; the 100 V rated EPC2038 eGaN FET used as the

synchronous bootstrap FET, and the 200 V rated EPC2019 eGaN FET

used in the SEPIC pre-regulator. The amplifier can be set to operate in

either differential mode or single-ended mode and includes the gate

driver(s), oscillator, and feedback controller for the pre-regulator that

ensures operation for wireless power control based on the AirFuel

standard. This allows for compliance testing to the AirFuel class 4

standard over a load range as high as ±35j Ω.

The EPC9512 can operate in either single-ended or

differential mode by changing a jumper setting. This allows

for high efficiency operation with load impedance ranges

suitable for single ended operation.

The circuits used to adjust the timing for the ZVS class-D

amplifiers have been separated to further ensure highest

possible efficiency setting. Each half bridge also includes

separate ZVS tank circuits.

The amplifier is equipped with a pre-regulator controller

that adjusts the voltage supplied to the ZVS class-D

amplifier based on the limits of 3 parameters: coil current,

DC power delivered to the ZVS class-D amplifier, and

maximum operating voltage of the ZVS class-D amplifier.

The coil current has the lowest priority followed by the

power delivered and amplifier supply voltage having

the highest priority. Changes in the device load power

demand, physical placement of the device on the source

coil and other factors, such as metal objects in proximity

to the source coil, contribute to variations in coil current,

DC power, and amplifier voltage requirements. Under any

of these conditions, the controller will ensure the correct

operating conditions for the ZVS class-D amplifier based

on the AirFuel standard. The pre-regulator can be bypassed

to allow testing with custom control hardware. The board

2 |

further allows easy access to critical measurement nodes for accurate

power measurement instrumentation hookup. A simplified diagram of

the amplifier board is given in figure 2.

The source and device coils are AirFuel compliant and have been pre-

tuned to operate at 6.78 MHz with the EPC9512 amplifier. The source

coil is AirFuel class 4 compliant and the device coils are AirFuel category 3

and category 5 compliant.

The EPC9513 (Category 3) device board includes a high frequency

Schottky diode based full-bridge rectifier, DC smoothing capacitor

and 5 V regulator. The regulator is based on a SEPIC converter that

features a 200 V EPC2019 eGaN FET. The power circuit is attached to

the backside of the coil which is provided with a ferrite shield that

prevents the circuit from shunting the coil's magnetic field.

The EPC9514 (Category 5) device board includes a high frequency

Schottky diode based full-bridge rectifier, DC smoothing capacitor

and 19 V regulator. The regulator is based on a SEPIC converter that

features a 100 V EPC2016C eGaN FET. The power circuit is attached

to the side of the coil.

For more information on the EPC8010, EPC2038, EPC2019, or

EPC2016C please refer to the datasheet available from EPC at

www.epc-co.com. The datasheet should be read in conjunction

with this quick start guide.

EPC9513

Category 3

Device Board

63 mm

EPC9512

Ampli er Board

60 mm

| EPC – EFFICIENT POWER CONVERSION CORPORATION |

Demonstration System EPC9129

EPC9514

Category 5

Device Board

152 mm

228 mm

Figure 1: EPC9129 demonstration system.