Файл: wirelesspowerspecificationpart1.pdf

3.3.2.1.2Shielding

Power Transmitter design B2 employs Shielding that is identical to the Shielding of Power Transmitter design B1. See Section 3.3.1.1.2.

3.3.2.1.3Interface Surface

The distance from the Primary Coil array to the Interface Surface of the Base Station is mm, across the top face of the Primary Coil array. See also Figure 3-37 in Section 3.3.1.1.3. In addition, the Interface Surface extends at least 5 mm beyond the outer edges of the Primary Coil array.

3.3.2.2Electrical details

The outline of the electrical diagram of Power Transmitter design B2 follows the outline of the electrical diagram of Power Transmitter design B1. See also Figure 3-38 in Section 3.3.1.2.

Power Transmitter design B2 uses a half-bridge inverter to drive the Primary Coil array. In addition, Power Transmitter design B2 uses a multiplexer to select the position of the Active Area. The multiplexer shall configure the Primary Coil array in such a way that one, two, or three sets of two Primary Coils are connected—in parallel—to the driving circuit. The connected Primary Coils together constitute a Primary Cell. As an additional constraint, the multiplexer shall select the Primary Coils such that each selected Primary Coil has an overlap with every other selected Primary Coil; see Figure 3-40(c) for an example.

Power Transmitter design B2 uses the input voltage to the half-bridge inverter to control the amount of power that is transferred. For this purpose, the input voltage range is 0…20 V, where a lower input voltage results in the transfer of a lower amount of power. In order to achieve a sufficiently accurate adjustment of the power that is transferred, a type B2 Power Transmitter shall be able to control the input voltage with a resolution of 35 mV or better.

When a type B2 Power Transmitter first applies a Power Signal (Digital Ping; see Section 5.2.1), it shall use an initial input voltage of 12 V.

Control of the power transfer shall proceed using the PID algorithm, which is defined in Section 5.2.3.1. The controlled variable ( ) introduced in the definition of that algorithm represents the input voltage to the half-bridge inverter. In order to guarantee sufficiently accurate power control, a type B2 Transmitter shall determine the amplitude of the current into the Primary Cell (i.e. the sum of the currents through each of its three constituent Primary Coils) with a resolution of 5 mA or better. In addition to the PID algorithm, a type B2 Power Transmitter shall limit the current into the Primary Cell to at most 3.5 A RMS in the case that the Primary Cell consists of two or three Primary Coils, or at most 1.75 A RMS in the case that the Primary Cell consists of one Primary Coil. For that purpose, the Power Transmitter may limit the input voltage to the half-bridge inverter to value that is lower than 20 V. Finally, Table 3-28 in Section 3.3.1.2 provides the values of several parameters, which are used in the PID algorithm.

3.3.2.3Scalability

Power Transmitter Design B2 offers the same scalability options as Power Transmitter design B1. See Section 3.3.1.3.

3.3.3Power Transmitter design B3

Power Transmitter design B3 enables Free Positioning, and has a design similar to Power Transmitter design B1. See Section 3.3.1 for an overview.

3.3.3.1Mechanical details

Power Transmitter design B3 includes a Primary Coil array as defined in Section 3.3.1.1.1, Shielding as defined in Section 3.3.1.1.2, and an Interface Surface as defined in Section 3.3.1.1.3.

3.3.3.1.1Primary Coil array

The Primary Coil array consists of a hybrid PCB/wire wound coil structure. As shown Figure 3-41(a), the central part of this structure is a 4-layer PCB. The inner two layers of this PCB each contain an identical grid of coils, where coresponding coils are connected in parallel to form a single two-layer Primary Coil. The outer two layers of the PCB serve as a mounting area for the wire wound Primary Coils (layers (a) and

(b). In addition, layer 4 of the PCB contains the leads to both the internal and the wire wound Primary Coils; and layer 1 can be used for any purpose, but shall not influence the inductance values of the Primary Coils.

The wire-wound Primary Coils consist of litz wire having 24 strands of no. 40 AWG (0.08 mm diameter), or equivalent. Each wire wound Primary Coil has a circular shape as shown in Figure 3-41 (b).

Each Primary Coil inside the PCB consists of a trace that runs through 18 hexagonal turns as shown in Figure 3-41 (c), and are identical to the Primary Coils of Power Transmitter design B2 defined in Section 3.3.2.1.1.

Figure 3-41(d) provides a top view of the Primary Coil array, showing that the individual Primary Coils are packed in a hexagonal grid. The solid hexagons show the closely packed structure of the grid of Primary Coils on layer (a) of the Primary Coil array. The dashed hexagon illustrates that the identical grids of Primary Coils on layers (2) and (3) are offset over a distance to the right, such that the centers of the Primary Coils in layers (2) and (3) coincide with the corners of Primary Coils in layer (a). Likewise, the dash-dotted hexagon illustrates that the grid of Primary Coils on layer (b) is offset over a distance to the left, such that the centers of the Primary Coils in layer (b) coincide with the corners of Primary Coils in layer (a). As a result, the centers, respectively corners, of the Primary Coils on layer (2) and (3), and the corners, respectively centers, of the Primary Coils on layer (b) coincide as well. All Primary Coils are stacked with the same polarity. See Section 3.3.3.2 for the meaning of the shaded hexagons.

Table 3-30 lists the relevant parameters of the Primary Coil array.

3.3.3.1.2Shielding

As shown in Figure 3-42, Transmitter design B3 employs Shielding to protect the Base Station from the magnetic field that is generated in the Primary Coil array. The Shielding extends to at least 2 mm beyond the outer edges of the Primary Coil array, and is placed at a distance of at most mm below the Primary Coil array.

The Shielding consists of soft magnetic material that has a thickness of at least 0.5 mm. This version 1.1.1 of the System Description Wireless Power Transfer, Volume I, Part 1, limits the composition of the Shielding to a choice from the following list of materials:

Material 78 — Fair Rite Corporation.

3C94 — Ferroxcube.

N87 — Epcos AG.

PC44 — TDK Corp.

Figure 3-42: Primary Coil array assembly of Power Transmitter design B3

3.3.3.1.3Interface Surface

As shown in Figure 3-42, the distance from the Primary Coil array to the Interface Surface of the Base Station is mm, across the top face of the Primary Coil array. In addition, the Interface Surface extends at least 5 mm beyond the outer edges of the Primary Coil array.

3.3.3.2Electrical details

As shown in Figure 3-43, Power Transmitter design B3 uses a full-bridge inverter to drive the Primary Coil array. In addition, Power Transmitter design B3 uses a multiplexer to select the position of the Active Area. The multiplexer shall configure the Primary Coil array in such a way that one, two, or three Primary Coils are connected—in parallel—to the driving circuit. The connected Primary Coils together constitute a Primary Cell. As an additional constraint, the multiplexer shall select the Primary Coils such that each selected Primary Coil has an overlap with every other selected Primary Coil; see Figure 3-41(d) for an example.

Full-bridge

Inverter

each individual Primary Coil in layer (b). The capacitances and inductance in the impedance matching