Texas Instruments bqTESLA bq500414Q, Руководство пользователя, Страница: 14 / 29

Test Setup
www.ti.com
6.2.2.2 Apply Receivers
Place the bq51013BEVM-764 EVM on the top of the transmitting coil. Align the centers of the receiving
and transmitting coils across each other. In the next few seconds, observe that the status LED, D6,
flashes green, indicating that communication between the transmitter and the receiver is established and
that power transfer has started.
• The status LED, D8, flashes a green light during power transfer.
• Typical output voltage is 5 V, and the output current range is 0 mA to 1 A.
6.2.2.3 Efficiency
To measure system efficiency, measure the output voltage, output current, input voltage, and input current
and calculate efficiency as the ratio of the output power to the input power. Connect voltage meters at the
input and output of TX and RX (see
Figure 4 ). Average the input current; the comm pulses modulate the
input current, distorting the reading. See Figure 5 for efficiency. Figure 5 shows efficiency with standard
EVM.
This shows the efficiency from transmitter input to receiver output. The input power SEPIC converter is
included in this circuit and loss is higher due to power loss in two converters. For this test, an input voltage
of 13.6 V was used.
Figure 5. Efficiency versus Power, bq500414QEVM-629 Transmitter and HPA764 Receiver
6.2.2.4 Efficiency
Efficiency is affected by changes in the power section. Higher R
DSON
MOSFET increases loss. This is a
design decision and a trade off between cost and performance.
Parts selected for the EVM design are optimized for efficiency.
Note that changing the efficiency of the unit and reducing loss (or increasing loss) changes the FOD and
the PMOD performance and may require re-calibration. This would require the FOD_CAL resistor (R52) to
change along with FOD_Threshold resistor (R3) and PMOD resistor (R22). The FOD and PMOD
calibration procedure must be repeated.
6.2.2.5 Input Power DC / DC Converter
To support the input voltage range for an automotive application, an optional wide input voltage converter
is installed on the board. The TPS40210 is configured as a Single-Ended Primary-Induction Converter
(SEPIC) providing a 12-V output from an input voltage that can be above and below 12V.
6.2.2.6 EMI Shield
The EVM is designed to support an EMI Shield above the coils to reduce emissions. The shield, PWR633,
is a comb-type filter that is effective between 100 kHz and 2 MHz.
14 bq500414Q bqTESLA Wireless Power TX EVM SLVUA40A – March 2014 – Revised January 2015
Submit Documentation Feedback
Copyright © 2014–2015, Texas Instruments Incorporated