Файл: wirelesspowerspecificationpart1.pdf

To execute this algorithm, the Power Transmitter shall execute the steps listed below, in the order of appearance. In the definitions of these steps, the index labels the sequence of Control Error Packets, which the Power Transmitter receives.

Upon receipt of the Control Error Packet, the Power Transmitter shall calculate the new

Primary Cell current ( )as

( ) ( ) ( )

where ( ) represents the actual Primary Cell current—reached in response to the previous Control Error Packet—and ( ) represents the Control Error Value contained in the Control

Error Packet. Note that ( ) represents the Primary Cell current at the start of the power transfer phase.

If the Control Error Value ( ) is non-zero, the Power Transmitter shall adjust its Primary Cell

oThe Power Transmitter shall calculate the difference between the new Primary Cell and the actual Primary Cell current as the error

loop. Note that ( ) represents the actual Primary Cell current at the start of the loop.

oThe Transmitter shall calculate the proportional, integral, and derivative terms (in any order):

oThe Power Transmitter shall calculate the sum of the proportional, integral, and derivative terms:

controlled variable at the start of the power transfer phase. The controlled variable is either the Operating Frequency, the duty cycle of the inverter, or the voltage input to the inverter. If the calculated ( ) exceeds the specified range (see the definition of the individual Power Transmitter designs in Section 3), the Power Transmitter shall replace the calculated ( ) with the appropriate limiting value.

The Power Transmitter shall determine the Primary Cell current ( ) exactly at

after the end of the Control Error Packet.

See the definition of the individual Power Transmitter designs in Section 3 for the values of , , , ,

and .

5.3Power Receiver perspective

Section 5.3.1 defines the initial response of the Power Receiver to the application of a Power Signal. As part of this initial response, the Power Receiver wakes up its Communications and Control Unit—if that is not already up and running. Section 5.3.2 defines the response of a Power Receiver to a Digital Ping. This response ensures the Power Transmitter that it is dealing with a Power Receiver (rather than some unknown object). Section 5.3.3 defines the response of a Power Receiver to an extended Digital Ping. This response enables the Power Transmitter to identify the Power Receiver and establish a Power Transfer Contract. Finally, Section 5.3.4 defines the protocol that the Power Receiver shall execute in order to control the power transfer from the Power Transmitter.

Many provisions in this Section 5.3 refer to the start and/or the end of a Packet, or the start of a Packet’s preamble. For the purpose of those provisions, the start of a Packet is defined as the instant the Power Receiver transmits the first edge of the start bit of the Packet’s header byte; the end of a Packet is defined as the instant the Power Receiver transmits the second edge of the stop bit of the Packet’s checksum byte; and the start of a Packet’s preamble is defined as the instant the Power Receiver transmits the first edge of the first preamble bit.

In addition to the timing constraints given in Sections 5.3.1, 5.3.2, 5.3.3, and 5.3.4, the Power Receiver shall

from the instant that the Primary Cell current amplitude crosses 50% of the stable level. Note that this version 1.1.1 of the System Description Wireless Power Transfer, Volume I, Part 1, does not define how the Power Receiver should detect that the Power Transmitter removes the Power Signal.

Table 5-5: Power Receiver reset timing

Moreover, notwithstanding the timing constraints given in Sections 5.3.1, 5.3.2, 5.3.3, and 5.3.4, the Power Receiver may stop transmitting Packets to the Power Transmitter at any time. (Informative) This behavior causes the Power Transmitter to remove the Power Signal, possibly under the assumption that a user has removed the Power Receiver from the Interface Surface. The recommended behavior to cause the Power Transmitter to remove the Power Signal (when a user has not removed the Power Receiver from the Interface Surface) is to transmit an End Power Transfer Packet as defined in Sections 5.3.2 and 5.3.4.

5.3.1Selection phase

As soon as the Power Transmitter applies a Power Signal, the Power Receiver shall enter the selection phase.7 Note that this version 1.1.1 of the System Description Wireless Power Transfer, Volume I, Part 1, does not define how the Power Receiver should detect that the Power Transmitter applies a Power Signal. If the Power Receiver considers the rectified voltage to be sufficiently high, the Power Receiver shall proceed to the ping phase, such that the first Packet (see Section 5.3.2) starts at . Here, the time starts from the instant that the Primary Cell current amplitude crosses 50% of the stable level. See Figure 5-7 and Table 5-6.

If the Power Receiver does not proceed to the ping phase, the Power Receiver shall not transmit any Packet.

7If the Power Receiver is not in the selection phase already. Note that if the Power Receiver needs time to start up its Communications and Control Unit, the Power Receiver shall consider itself to be in the selection phase during that start-up time. In general, the Power Receiver may consider itself to be in the selection phase whenever it is neither in the ping phase, nor in the identification & configuration phase, nor in the power transfer phase.

Figure 5-7: Power Receiver timing in the selection phase

Table 5-6: Power Receiver timing in the selection phase

5.3.2Ping phase

If the Power Receiver responds to te Digital Ping, the Power Receiver shall transmit either a Signal Strength Packet, or an End Power Transfer Packet as its first Packet. The Power Receiver shall transmit this first Packet immediately upon entering the ping phase.

First Packet

Figure 5-8: Power Receiver timing in the ping phase

After the Power Receiver has transmitted a Signal Strength Packet, the Power Receiver shall proceed to the identification & configuration phase. After the Power Receiver has transmitted an End Power Transfer Packet, shall remain in the ping phase. In that case, the Power Receiver should transmit additional End Power Transfer Packets.8

5.3.3Identification & configuration phase

In the identification & configuration phase, the Power Receiver shall transmit the following sequence of Packets:

If the Power Receiver enters the identification & configuration phase from the ping phase, an Identification Packet.

If the Ext bit of the preceding Identification Packet is set to ONE, an Extended Identification Packet.

Up to 7 optional configuration Packets from the following set (the order in which the Power Receiver transmits these Packets, if any, is not relevant):

oAny Proprietary Packet (as listed in Table 6-3).

A Configuration Packet.

The Power Receiver shall transmit the above sequence of Packets subject to the following timing constraints:

The Power Receiver shall not start the preamble of the next Packet in the sequence within the

8The Power Transmitter can miss the first End Power Transfer Packet, e.g. due to a communications error, and continue to apply the Power Signal.

It is recommended that the Power Receiver determines its actual Control Point at after the end of a Control Error Packet.

The first Received Power Packet shall start within the time window after the start of the Configuration Packet. A next Received Power Packet shall start within the time window

after the start of the preceding Received Power Packet.

The Power Receiver shall determine the average power received through its Interface Surface in a

See Figure 5-10 and Table 5-8.

In addition to the above timing constraints, if the Power Receiver has transmitted an End Power Transfer Packet, which contains an End Power Transfer Code of 0x07, the Power Receiver shall revert to the identification & configuration phase. Moreover, if the Power Receiver has transmitted an End Power Transfer Packet, which contains any other End Power Transfer Code, the Power Receiver shall remain in the power transfer phase, until the Power Transmitter removes the Power Signal. Furthermore, the Power Receiver should transmit additional End Power Transfer Packets if the Power Transmitter does not remove the Power Signal.9

tinterval

Next Control Error

Control Error

tdelay

treceived

(b)

Next Received Power

Received Power

Figure 5-10: Power Receiver timing in the power transfer phase

Table 5-8: Power Receiver timing in the power transfer phase

9(Informative) The Power Transmitter can miss the first and possibly subsequent End Power Transfer Packets, e.g. due to communications errors, and continue to apply the Power Signal. However, eventually the Power Transmitter should remove the Power Signal due to a time-out as defined in Section 5.2.3.