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2 Power Transmitter Designs

This Section contains the definition of the new Power Transmitter design A13. The provisions in this Section will be integrated into [Part 1] in a next release of this System Description Wireless Power Transfer.

2.1Power Transmitter design A13

Figure 2-1 illustrates the functional block diagram of Power Transmitter design A13, which consists of two major functional units, namely a Power Conversion Unit and a Communications and Control Unit.

Figure 2-1: Functional block diagram of Power Transmitter design A13

The Power Conversion Unit on the right-hand side of Figure 2-1 comprises the analog parts of the design. The inverter converts the DC input to an AC waveform that drives a resonant circuit, which consists of the selected Primary Coil plus a series capacitor. The selected Primary Coil is one from a linear array of partially overlapping Primary Coils, as appropriate for the position of the Power Receiver relative to the Primary Coils. Selection of the Primary Coil proceeds by the Power Transmitter attempting to establish communication with a Power Receiver using any of the Primary Coils. Note that the array may consist of a single Primary Coil only, in which case the selection is trivial. Finally, the current sense monitors the Primary Coil current.

The Communications and Control Unit on the left-hand side of Figure 2-1 comprises the digital logic part of the design. This unit receives and decodes messages from the Power Receiver, configures the Coil Selection block to connect the appropriate Primary Coil, executes the relevant power control algorithms and protocols, and drives the frequency of the AC waveform to control the power transfer. The Communications and Control Unit also interfaces with other subsystems of the Base Station, e.g. for user interface purposes.

2.1.1.1Mechanical details

Power Transmitter design A13 includes one or more Primary Coils as defined in Section 2.1.1.1.1, Shielding as defined in Section 0, an Interface Surface as defined in Section 2.1.1.1.3.

Figure 2-4: Primary Coil assembly of Power Transmitter design A13

2.1.1.1.3Interface Surface

As shown in Figure 2-4, the distance from the Primary Coil to the Interface Surface of the Base Station is mm, across the top face of the Primary Coil. In the case of a single Primary Coil, the distance from the Primary Coil to the Interface Surface of the Base Station is mm, across the top face of

the Primary Coil. In addition, the Interface Surface of the Base Station extends at least 5 mm beyond the outer dimensions of the Primary Coils.

2.1.1.1.4Inter coil separation

If the Base Station contains multiple type A13 Power Transmitters, the Primary Coils of any pair of those Power Transmitters shall have a center-to-center distance of at least mm.

2.1.1.2Electrical details

As shown in Figure 2-5, Power Transmitter design A13 uses a full-bridge inverter to drive an individual Primary Coil and a series capacitance. Within the Operating Frequency range specified below, the

Power Transmitter design A13 uses the input voltage of the inverter to control the amount of power that is transferred. For this purpose, the input voltage has a range of 1…12 V, with a resolution of 10 mV or better. The Operating Frequency is kHz, with a duty cycle of 50%.

When a type A13 Power Transmitter first applies a Power Signal (Digital Ping; see [Part 1] Section 5.2.1), it shall use an initial voltage of V for a bottom Primary Coil, and V for a top Primary Coil, and a recommended Operating Frequency of 110 kHz.

Control of the power transfer shall proceed using the PID algorithm, which is defined in [Part 1], Section 5.2.3.1. The controlled variable ( ) introduced in the definition of that algorithm represents the input voltage to the inverter. In order to guarantee sufficiently accurate power control, a type A13 Power Transmitter shall determine the amplitude of the Primary Cell current—which is equal to the Primary Coil current—with a resolution of 7 mA or better. Finally, Table 2-2, Error! Reference source not found., and Error! Reference source not found. provide the values of several parameters, which are used in the PID algorithm.