WO2022227008A1

WO2022227008A1 - Dc/dc converter-less wireless charging device

Info

Publication number: WO2022227008A1
Application number: PCT/CN2021/091507
Authority: WO
Inventors: Stephane SCHULER
Original assignee: Shanghai Square Plus Information Technology Consulting Ltd.
Priority date: 2021-04-30
Filing date: 2021-04-30
Publication date: 2022-11-03

Abstract

A charging controller (100) for a wireless charging transmitter is provided. The charging controller (100) comprises a voltage inverter (130) with output terminals electrically connectable to an inductive wireless charging antenna (150) and configurable to operate the voltage inverter (130) at a nominal switching frequency, fop. The nominal switching frequency has an associated period, Top, wherein the period, Top, comprises a first half period, Tpos, and a second half period, Tneg. The charging controller (100) is configured to supply to the output terminals in the first half period, Tpos, an output signal comprising a sequence, Spos, of pulses at a toggling frequency, fsw, the pulses alternating between a positive amplitude, Vpos, and an off-state, and in the second half period, Tneg, an output signal comprising a sequence, Sneg, of pulses at a toggling frequency, fsw, the pulses alternating between an off-state and a negative amplitude, Vneg. The arrangement enables the power level of the charging transmitter to be varied by changing the shape of the sequence of pulses, thus removing the need for a variable DC-DC converter (120).

Description

DC/DC CONVERTER-LESS WIRELESS CHARGING DEVICE

FIELD OF INVENTION

The field of the invention is wireless charging devices.

BACKGROUND OF INVENTION

Wireless charging applications for smartphones are increasingly popular, mostly for the convenience they offer. In an automotive context, wireless charging transmitters enhance safety by providing a repository for the driver’s phone, reducing driver distraction (most countries around the world are prohibiting smartphone usage while driving) and avoiding the need for charger cords that may present a danger of becoming entangled with the vehicle controls.

Several wireless charging methods have been proposed. However, only the Wireless Power Consortium (WPC) with the Qi standard has been widely accepted and embedded by the smartphone makers, making it the de-facto wireless charging standard. The Qi standard was originally engineered for consumer electronics applications, allowing smartphone makers to develop their private charging ecosystem.

However, wireless charger transmitters are significantly more complex than standard USB chargers, primarily leading to significantly higher cost of material and consequently higher sales prices. These costs are today considered the main hurdle to the wireless charging market proliferation.

In the automotive market, the wireless charging pad application has been often left in the car dealers option list for the time wireless charging was limited to high end smartphones. With the function becoming more standard in smartphones, the safety and comfort benefits of wireless solutions started to offset the cost issue, leading the vehicle manufacturer to first mount the application.

In order to mitigate high costs and increase attractiveness of this type of device, many automobile makers have considered the wireless charger repository as a hub for close range interactions between the smartphone and the vehicle. Examples are Near Field Communication (NFC) or a Long Term Evolution (LTE) coupler.

However, in spite of these developments, no significant cost improvements have been achieved with respect to the wireless charging transmitter function itself.

SUMMARY OF INVENTION

According to a first aspect, there is provided a charging controller for a wireless charging transmitter. The charging controller comprises a voltage inverter with output terminals electrically connectable to an inductive wireless charging antenna and configurable to operate the voltage inverter at a nominal switching frequency, f _op. The nominal switching frequency has an associated period, T _op, wherein the period, T _op, comprises a first half period, T _pos, and a second half period, T _neg. The charging controller is configured to supply to the output terminals in the first half period, T _pos, an output signal comprising a sequence, S _pos, of pulses at a toggling frequency, f _sw, the pulses alternating between a positive amplitude, V _pos, and an off-state, and in the second half period, T _neg, an output signal comprising a sequence, S _neg, of pulses at a toggling frequency, f _sw, the pulses alternating between an off-state and a negative amplitude, V _neg.

The toggling frequency, f _sw, is amultiple, N, of the voltage inverter nominal switching frequency, f _op, and, N, is a positive number greater than 1. The voltage levels, V _pos, and V _neg, are of opposite polarity. The charging controller is configured to select, from a plurality of pre-defined sets, an initial set of toggling sequences, S _pos, and, S _neg, that provide a power level corresponding to an initial power level.

In an embodiment, the charging controller is configured to provide a voltage inverter output signal alternating the sequences, S _pos, and, S _neq, characterized by the amplitude of the fundamental frequency, f _op, carried power.

In an embodiment, the charging controller is further configured to receive a requested power value from an in-charge device, receive a received power value from an in-charge device and, in response to a difference between the requested power value and the received power value, select new toggling sequences, S _pos, and, S _neq, from the plurality of pre-defined sets. The new toggling sequence provides a power level closer to the requested power level than the initial set.

In an embodiment, the charging controller is configured to select the toggling sequences, S _pos, and, S _neq, using a lookup table.

In an embodiment, the lookup table associates a plurality of voltage inverter output signal power levels to corresponding sequences, S _pos, and, S _neq, delivering that power level.

In an embodiment, the charging controller is configured to set, N, to be greater than or equal to 24, and optionally greater than or equal to 32, and optionally greater than or equal to 160.

In an embodiment, the charging controller is configured to provide the toggling sequences such that, S _pos, and, S _neq, are identical or reversed.

In an embodiment, the voltage inverter is an H-bridge topology voltage inverter.

In an embodiment, the charging controller further comprises an amplitude modulation (AM) demodulator circuit configured to demodulate a load modulated signal sent by an in-charge device and to extract data from the modulated signal.

In an embodiment, the charging controller further comprises a voltage inverter driver to control the voltage inverter output signal and generate, S _pos, and, S _neq, alternating toggling sequences at the toggling frequency, f _sw.

In an embodiment, the voltage inverter driver further comprises a clocking system configurable to programmably frequency modulate the toggling frequency, f _sw, in polarity and depth.

In an embodiment, the charging controller further comprises a microcontroller to control a wireless charging operation by controlling the voltage inverter based on the received data from the in-charge device through the demodulator circuit.

According to a second aspect, there is provided a charging controller for a wireless charging transmitter comprising a voltage inverter, wherein the voltage inverter comprises a first low side switch controllable by a first signal and a first high side switch controllable by a second signal, a second low side switch controllable by a third signal, a second high side switch controllable by a fourth signal and output terminals electrically connectable to an inductive wireless charging antenna. The controller is configurable to operate at a nominal frequency, f _op, the nominal frequency having an associated period, comprising a first half period and a second half period. The charging controller comprises a voltage inverter driver, wherein the voltage inverter driver is configured to provide, in the first half period, the second signal and the third signal at a level associated with an off-state of the respective switches, and the first signal comprising a first toggling sequence, S ₁, and the fourth signal comprising a fourth toggling sequence, S ₄,. In the second half period, the voltage inverter driver is configured to provide the first signal and the fourth signal at a level associated with an off-state of the respective switches, and the second signal comprising a second toggling sequence, S ₂, and the third signal comprising a third toggling sequence, S ₃. The charging controller is configured to select, from a plurality of pre-defined sets, an initial set of toggling sequences, S ₁, S ₂, S ₃, and, S ₄, that provide a power level corresponding to an initial power level.

In an embodiment, each toggling sequence comprises toggled on-states and off-states at levels associated respectively with an on-state and an off-state of the respective switches. The first toggling sequence has a first toggling frequency, f _sw1 wherein the first toggling frequency is a multiple by a first multiple, N ₁, of the wireless charger nominal frequency, f _op, the second toggling sequence has a second toggling frequency, f _sw2 wherein the second toggling frequency is a multiple by a second multiple, N ₂, of the wireless charger nominal frequency, f _op, the third toggling sequence has a third toggling frequency, f _sw3, wherein the third toggling frequency is a multiple by a third multiple, N ₃, of the wireless charger nominal frequency, f _op, and the fourth toggling sequence has a fourth toggling frequency, f _sw4, wherein the fourth toggling frequency is a multiple by a fourth multiple, N ₄, of the wireless charger nominal frequency, f _op. N ₁ , and, N ₄, are positive numbers, and at least, N ₁, or, N ₄, is greater than 1 and N ₁, and, N ₄, are positive numbers, and at least, N ₁ , or, N ₄, is greater than 1.

In an embodiment, the voltage inverter driver further comprises a clocking system configurable to programmably frequency modulate the toggling frequency, f _sw1, f _sw2, f _sw3, and, f _sw4, of the switch control signals S ₁, S ₂, S ₃, and, S ₄, in polarity and depth.

In an embodiment, the charging controller is further configured to a requested power value from a charging device, receive a received power value from a charging device; and in response to a difference between the requested power value and the received power value, select a new toggling sequence from the plurality of pre-defined sets, the new toggling sequence providing a power level closer to the requested power level than the initial set.

In an embodiment, the charging controller is configured to select the toggling sequences, S ₁, S ₂, S ₃, and, S ₄, using a look-up table.

In an embodiment, the charging controller is configured to set, N ₁, N ₂, N ₃, N ₄, such that either, N ₂, and, N ₄, are equal to 1 and, N ₁, is equal to, N ₃, or, N ₁, and, N ₃, are equal to 1 and, N ₂, is equal to, N ₄.

In an embodiment, the charging controller is configured to set, N ₁, N ₂, N ₃, N ₄, to an integer, N, corresponding to a required resolution.

In an embodiment, the charging controller further comprises a look-up table defining, for each of a plurality of required power levels for energizing the inductive wireless antenna, reconstruction information for reconstructing a respective first sequence, S ₁, a respective second sequence, S ₂, a respective third sequence, S ₃ and a respective fourth sequence, S ₄. Each of the respective sequences comprises a sequence of on and off states according to respective predefined frequencies according to the required power level. The reconstruction information comprises a sequence, S, corresponding to a half period for at least one switch, wherein the half period is a period in which the switch is at a level associated with an on-state of the switch for at least part of the half period. The voltage inverter driver is configured to receive a required power level, access the look-up table to retrieve the reconstruction information required for reconstructing a first sequence, S ₁, second sequence, S ₂, third sequence, S ₃, and fourth sequence, S ₄, associated with the required power level, reconstruct, from the reconstruction information, each of respective first reconstructed sequence, S ₁, second reconstructed sequence, S ₂, third reconstructed sequence, S ₃, and fourth reconstructed sequence, S ₄, associated with the required power level, and supply to the voltage inverter a first signal comprising the reconstructed first sequence, S ₁, to the first switch, a second signal comprising the reconstructed second sequence, S ₂, to the second switch, a third signal comprising the reconstructed third sequence, S ₃, to the third switch and a fourth signal comprising the reconstructed fourth sequence, S ₄, to the fourth switch.

In an embodiment, the charging controller is configured to provide the toggling sequences such that, S ₁, and, S ₃, are identical or reversed, and such that, S ₂, and, S ₄, are identical or reversed.

In an embodiment, the charging controller further comprises a microcontroller for controlling a wireless charging operation.

According to a third aspect, there is provided a wireless charging transmitter further comprising a controller according to the first aspect or the second aspect, and further comprising: an inductive wireless charging antenna electrically connected to the output terminals of the voltage inverter; and a DC power source to supply the controller.

In an embodiment, the wireless charger further comprises a DC-DC converter, configured to receive power from the DC power source at a first voltage and provide power to the voltage inverter at a second voltage, the second voltage being higher than the first voltage.

In an embodiment, the wireless charging transmitter further comprises a low-pass or band-rejection filter installed between the voltage inverter and the inductive wireless charging antenna and a Power Line filter installed downstream the DC power source.

According to a fourth aspect, there is provided a method of operating a charging controller according to the first aspect. The method comprises selecting, from a plurality of pre-defined sets, an initial set of toggling sequences, S _pos, and, S _neg, that provide a power level corresponding to an initial power level, providing in the first half period, T _pos, an output signal comprising the sequence, S _pos, of pulses at a toggling frequency, f _sw, the pulses alternating between a positive amplitude, V _pos, and an off-state, and providing in the second half period, T _neg, an output signal comprising the sequence, S _neg, of pulses at a toggling frequency, f _sw, the pulses alternating between an off-state and a negative amplitude, V _neg. The toggling frequency, f _sw, is a multiple, N, of the voltage inverter nominal switching frequency, f _op, and, N, is a positive number greater than 1, and wherein the voltage levels, V _pos, and V _neg, are of opposite polarity.

According to a fifth aspect, there is provided a method of operating a charging controller according to the second aspect. The method comprises selecting, from a plurality of pre-defined sets, an initial set of toggling sequences, S ₁ , S ₂, S ₃, and, S ₄, that provide a power level corresponding to an initial power level, providing in the first half period the second signal and the third signal at a level associated with an off-state of the respective switches, and the first signal comprising the first toggling sequence, S ₁, andthe fourth signal comprising the fourth toggling sequence, S ₄, and providing in the second half period the first signal and the fourth signal at a level associated with an off-state of the respective switches, and the second signal comprising a second toggling sequence, S ₂, and the third signal comprising a third toggling sequence, S ₃.

BRIEF DESCRIPTION OF DRAWINGS AND GRAPHS

Embodiments will now be described with reference to the drawings, in which:

Fig. 1A and 1B are functional diagrams of current state of the art solutions that have been certified by the Wireless Power Consortium and that can be easily found on the market. Fig 1B, compared to Fig. 1A shows the implementation of an additional high order low-pass filter aimed at preventing the AM-Band jamming caused by the charging antenna power feed signal and a power line filter to prevent interferences through line conduction;

Fig. 1C is a flowchart illustrating a method of regulating the wireless transmission power in the state of the art configurations of Fig. 1A and 1B;

Fig. 2A to 2F are graphs illustrating six examples of analogue time signal shapes with decreasing carrying energies;

Fig. 3A and 3B are functional diagrams illustrating a wireless charging device and controller according to embodiments;

Fig. 4A to 4F are graphs illustrating respective Pulse Width Modulation signals of resolution N equals to 24 carrying the same amount of energy corresponding to Fig. 2A through Fig. 2F according to embodiments;

Fig. 5A and 5B are graphs illustrating examples of sequential signal organizations according to embodiments;

Fig. 5C is a table illustrating a lookup table with 512 energy steps exemplifying a possible control table by using a 24 bits pulse width modulation according to embodiments;

Fig. 6A and 6B are schematic diagrams illustrating electronic circuits that generate the signal of Fig. 5C embedded in the circuits of Fig. 3A and Fig. 3B respectively;

Fig. 6C and 6D are part schematic and part graphical diagrams illustrating two configuration options to control the H-Bridge switches according to embodiments;

Fig. 6E is a flowchart illustrating a method regulating the wireless transmission power with the hardware configurations of Fig. 3A and 3B and the lookup table of Fig. 5C; and

Fig. 6F is a flowchart illustrating the regulation of power in a system according to embodiments.

DETAILED DESCRIPTION

Embodiments of the present disclosure are described below in details with reference to the accompanying figures. Like elements in the various figures may be denoted by like reference numerals for consistency. Further, in the following detailed description, numerous specific details are set forth in order to provide a more thorough understanding of the claimed subject matter. However, it will be apparent to one having ordinary skill of the art that the invention is not limited to these embodiments, rather, the invention is defined by the claims. In other instances, well-known features have not been described in detail to avoid unnecessarily complicating the description.

Those skilled in the art would appreciate how the term motor vehicle hereafter may be understood to be a truck, a car, a sport utility vehicle or a suburban utility vehicle (SUV) , or any known automobile in the art. As used herein, the term "coupled" or "coupled to, "openable to" or "operatively connected to, " or "connected" or "connected to" may indicate establishing either a direct or indirect connection and is not limited to either unless expressly referenced as such. Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale und certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification.

In general, the invention relates to a wireless charging transmitter working according to the Qi standard released by the Wireless Power Consortium. The person skilled in the art would appreciate the invention may be adapted to other systems not compliant with the standard. In the Qi standard, the in-charge device is the master, which supervises the charging process of the battery to be charged. All safety aspects of the process are managed by the in-charge device. The wireless charging transmitter is the slave of the system, executing requests from the in-charge device. The stages of the process are as follows:

- Requests from the in-charge device are transmitted to the charger using a low frequency AM load modulation superposed to the power signal sent by the wireless charging transmitter.

- The original system of the Qi standard relied upon a unidirectional communication between the in-charge device and the wireless charging transmitter. This system left an option to adjust the transmitted power using a Pulse Width Modulation (PWM) power signal to adjust the transmitting power.

- With the evolution of the system to transmit a higher power level (up to 15W) , instead of the initial 5W for which it was originally designed, the new extended power systems require a bi-directional communication between the wireless charging transmitter and the wireless charging device. While the downlink communication remains the AM load modulation of the original specification, a new uplink communication path has been defined to enhance the safety of the charging process and satisfy fixed power signal frequency requirements expected by the charging device manufacturers. This uplink communication is defined as a configurable Frequency Modulation (FM) . This has the consequence of no longer allowing the usage of a Pulse Width Modulation (PWM) as adjustment factor of the transmitted power.

- As a consequence, the transmitted power now has to be set by adjusting the power signal amplitude, the only obvious method left to control the power of a signal without interfering with the communication. This has led to the implementation of controlled output voltage DC-DC converters, creating an uncompensated cost in implementing the wireless charging transmitter.

USB chargers are significantly cheaper to build than wireless chargers. Additionally, they also feature better performances in terms of charging durations, which is the end user main performance indicator besides the acquisition costs. In this context, a more complex wireless charging transmitter with additional costs without additional benefits was understandably not welcomed. It is nowadays considered a main brake to the system expansion.

In an automotive context, wireless charging transmitters remain in high demand due to the benefits they offer, in particular the enhanced safety provided by limiting driver distractions and avoiding potential entanglement of charging cables with the vehicle controls. The pressure on cost in the industry remains, however, high.

While remaining compatible with the Qi standard, the present invention proposes to remove the need for a DC-DC converter and related cost, by using the voltage inverter to control the power. Instead of adjusting the power by voltage, the power can be set by changing the shape of the inverted signal.

The embodiments described herein relate to the definition and generation of a power feed signal for a wireless charging antenna with the purposes of minimizing the cost of the function by removing the need for a controlled output voltage DC-DC converter while using the other existing functional blocks without increasing their cost.

In embodiments, construction is segmented in two parts:

- The first part consists in a new definition of the voltage inverter output power feed signal that allows adjusting the power of the radiated signal.

- The second part consists of electronic circuitry configured to generate the power feed signal defined in the first part. Since many alternatives and variants would be apparent to the skilled person, both in terms of circuitry and/or integration, embodiments are described which focus on a single versatile solution allowing all possible configurations of the newly defined voltage inverter output power feed signal.

Fig. 1A and 1B are functional diagrams which describe current state of the art solutions that are certified by the Wireless Power Consortium within its Qi standard. For simplification purposes, some functions (mostly monitoring) have been omitted in the description and figures. In embodiments, these functions may be implemented in the way they are in the state of the art solutions. However, for some topologies, the absence of filters may present some opportunities for safety improvement.

Fig. 1A and 1B only show a single charging antenna for simplification purposes. However, many systems use three or more charging antennas that are selected through a multiplexer. The multiplexer has been omitted for simplicity.

The DC power source 190 is not considered part of the wireless charging system since it is dependent on the environment (for example 12V for most automotive applications) .

Fig. 1A is a functional diagram illustrating the basic components needed to build a wireless charging function. From a high level perspective, a wireless charger transmitter can been made of two main functional blocks, namely:

- A charging controller 100 which manages all aspects of the wireless power transfer, implementing the Wireless Consortium Qi standard.

- A wireless charging antenna 150 which comprises at least one radiating coil 151 coupled serially to a capacitance (not illustrated) . The serial inductance 151 and coupled capacitance implement a low-pass filter, for which the cut-off frequency f _c is typically set just below 100kHz.

The charging controller 100 block is further broken down into four sub-blocks:

- A voltage inverter driver 110 itself embedding a microcontroller 115 which executes a firmware code implementing the Wireless Consortium Qi standard and interfaces to and from the other sub-blocks of the charging controller 100 and the wireless charging antenna 150.

- A voltage inverter 130, which converts the power supply DC output voltage 125 into an AC square signal 135 which is used to feed the wireless charging antenna 150. Usually, the voltage inverter 130 is an H-bridge topology inverter made of four switches, typically power MOSFETs that are controlled by the voltage inverter driver 110. A nominal operating frequency f _op is defined in accordance with the Qi standard. This operating frequency f _op is typically in the range of 100 to 140kHz. According to the Qi standard, from version 1.3 onwards, the voltage inverter 130 is further controlled to superimpose a Frequency Shift Keying (FSK) modulation used for digital communication towards the in-charge device 180.

- A DC-DC converter 120 which converts a DC input voltage 195 from the DC power source 190 into the DC output voltage 125 needed to provide the requested power by the in-charge device (a smartphone for example) . The DC output voltage 125 is controlled by the voltage inverter driver 110. The control method of the DC output voltage 125 can be either directly through a Pulse width modulation signal (PWM) or any digital communication 105 between the voltage inverter driver and the DC-DC converter 120. The DC-DC converter 120 can be a Buck or Buck-Boost topology, depending on requirements.

- An Amplitude Modulation (AM) demodulator 160 which demodulates the signal received from the in-charge device 180 through load modulation according to the Qi standard and feeds it back to the microcontroller 115, thus closing the charging regulation loop. This demodulation is typically implemented by a simple low-pass envelope detector that is read by the microcontroller 115 through an input capture port 165.

Fig. 1B is a functional diagram illustrating a variation of the functional diagram which does not jam the AM-Band radio. All of the blocks and sub-blocks of Fig. 1A are included, each operating in the same manner as described above. The following additional blocks are provided:

- A high order low-pass filter 140 is inserted between the voltage inverter 130 and the wireless charging antenna 150. Its primary purpose is to attenuate the interference potential of the voltage inverter 130 output AC signal 135 harmonics above the operating frequency f _op.

- A power line filter 145 is provided upstream of the DC-DC converter 120. Its purpose is to reduce the transmission of interference from the voltage inverter 130 along the wireless charger transmitter power supply lines. This filter usually comprises a power choke combined with one or more inductors to create a low-pass filter. The power line filter 145 may not be needed for consumer market wireless charger transmitters. In automotive applications, however, it is mandatory to prevent interference from radiating through the vehicle wire harness.

Fig. 1C is a flowchart illustrating the power regulation process of the wireless charging transmitter executed by the microcontroller 115. Only the steps relevant to the regulation loop are described. For clarity, the essential functions performed by hardware have corresponding references to those of Fig. 1A and 1B. The method comprises:

- Obtaining, as per the Qi Standard, the requested power P _request and the received power P _received from the in charge target device by extracting relevant data from the demodulated signal received from the in-charge device at step 112.

- Computing at step 113, a DC-DC output voltage V ₁₂₅ using standard electrical circuit calculations. This step may be as simple as:

(for Fig. 1A configuration) Equation 1

- Computing at step 119, the pulse width modulation signal or the command required to adjust the output voltage V ₁₂₅ of the DC-DC converter 120.

- Radiating by the wireless charger transmitter the power P ₁₅₀ through the wireless charging antenna, at 150.

- Measuring by the in-charge device the received Power P _received and broadcasting it back to the transmitter through load modulation.

- Demodulating the received message by the AM demodulator at 160 and returning to step 112, thus closing the regulation loop.

- Responding to the transmitter by accordingly either increasing, decreasing or keeping the same power transmission settings by adjusting the output voltage V ₁₂₅ of the DC-DC converter 120.

Nowadays, many wireless charging transmitters makers select the frequency f _op at 127.7kHz, a frequency that offers additional benefits that are well known by persons skilled in the art. For simplification purposes, this frequency f _op has been used as a baseline for all graphs of this disclosure. The invention, however, is not limited to this particular frequency f _op.

In order to understand the inventive concept, an analysis is now provided of the frequency signatures of signals that may be used for driving a voltage inverter. The person skilled in the art would appreciate that this is for understanding of the invention and that there are a number of ways of determining required signals, including through empirical measurement.

In order to avoid complex calculations that are irrelevant to convey the invention concept, the following analysis is based on the simplifying assumption that the wireless charger transmitter functional blocks are “ideal” . This provides a useful approximation to reality:

- The voltage inverter 130 switches are assumed without losses.

- The wireless charging antenna 150 is assumed to behave like an ideal filter, fully filtering the harmonics of the f _op antenna power feed signal 135.

- If implemented, the high order low-pass filter 140 is assumed to behave like an ideal filter, fully filtering the harmonics of the f _op voltage inverter 130 output signal 135.

Obviously, an actual implementation will require computation assuming the actual wireless charging antenna 150 characteristics and the actual high order low-pass filter 140 features.

Fig. 2A is a graph illustrating the temporal response of the voltage inverter AC signal output 135 as used by the state of the art solutions illustrated in Fig. 1A and 1 B, and described above. The voltage inverter 130 is controlled so as to generate a square signal 230. For comparison purposes, a pure sinusoidal signal 220 with the same amplitude has been illustrated as well.

The Fourier series for the square signal of normalized amplitude 1 Volt is:

As explained above, the perfect filters are applied for simplification purposes. The fundamental f _op amplitude of the sine signal after filtering is 4/π Volt and is proportional to the energy transferred by the wireless charger transmitter to the wireless charging device.

The Fourier series for the trapezoid signal of normalized amplitude 1 Volt is:

The fundamental f _op amplitude of the sine signal after filtering is (4/π) (sin α/α) Volt and is proportional to the energy transferred by the wireless charger transmitter to the wireless charging device. (sin α/α) is a coefficient smaller than 1. The greater the angle α, the smaller the energy transferred by the wireless charger transmitter to the wireless charging device. Fig. 2B and 2C are graphs illustrating respectively two examples of trapezoid signals for α equal to 29.25deg (signal 240) and α equal to 56.25deg (signal 250) respectively.

When α reaches π/2, the trapezoid signal becomes triangular. At α equal π/2, the triangular signal 260 has an amplitude of 1 Volt as represented in Fig. 2D.

The Fourier series for the triangular signal of normalized amplitude 1 Volt is:

The fundamental f _op amplitude of the sine signal after filtering is (8/π ²) Volt and is proportional to the energy transferred by the wireless charger transmitter to the wireless charging device. For α greater than π/2, the triangular signal amplitude decreases as represented in Fig. 2E and 2F for amplitude 0.8 (signal 270) and 0.25 (signal 280) respectively and the fundamental amplitude f _op amplitude of the sine signal after filtering becomes (8A/π ²) Volt where A is the amplitude of the triangular signal.

In the Wireless Power Consortium Qi standard, the power delivered to the in-charge device by the wireless charging transmitter is determined by the amplitude of the antenna power feed signal 135, as illustrated in Fig. 1A or 145 in Fig. 1 B. With frequency modulation used for communication towards the in-charge device, the practical adjustment of the transmitted power is implemented by setting the amplitude of the antenna

power feed signal

135 or 145. This function is realized by the DC-DC converter 120 which provides a regulated DC voltage output 125 to the voltage inverter 130. As a result, the voltage inverter 130 output signal 135 is an AC square signal which amplitude is two (2) times the regulated DC voltage output 125.

To realize a cost saving, the present disclosure removes the need for the output voltage controlled DC-DC converter 120 and allocates the power adjustment function to the voltage inverter 130. Using this principle, the transmitted power would no longer be controlled by controlling the amplitude of the voltage inverter 130 output signal 135. Instead the

antenna power signal

135 or 145 would be adjusted by altering the shape of the signal generated by the voltage inverter 130.

Fig. 3A and 3B are functional diagrams illustrating the evolution of the circuit flow chart according to an embodiment. Compared with previous embodiments, the output voltage controlled DC-DC converter 120 has been removed and replaced by a connection 320 connecting the DC input voltage 195 and the voltage inverter input voltage 125:

- The DC-DC converter deletion removes the need for the voltage inverter driver 110 control signal 105. However in many systems the connection may be kept as an input for DC power source voltage 195 level monitoring purposes.

- In most applications, the DC input voltage 125 can no longer be considered a fixed and known value by design. The connection 320 is consequently fed back to the microcontroller 115 for monitoring purposes since it enters the computation of the voltage inverter output signal 135.

In Fig. 3A and 3B, the microcontroller 115 controls the energy transmitted to the wireless charging device by altering the shape of the voltage inverter output signal 135 used to feed the wireless antenna 150 either directly as in Fig. 3A or through the low-pass filter 140 like in Fig. 3B.

In embodiments, there is further provided a fixed DC-DC converter, disposed between the DC power source 190 and the voltage inverter 130. This enables the provision of a higher voltage to the voltage inverter 130 than is provided by the DC power source 190 to reach higher transmission powers. Unlike in the state of the art solution, this is a fixed converter, providing a fixed ratio of input to output voltage. In an embodiment, the output voltage may be boosted to 15 V. In an embodiment, this may be 18V. The person skilled in the art will appreciate that other output levels may be provided and be within the scope of the invention.

Generating any of the

signals

220, 230, 240, 250, 260, 270, 280 represented in Fig. 2A to 2F out of a DC power source can be realized in many ways. However, for power signals, it is not an easy task. While most of the known techniques work well for low power signals, only a few are suited to generate energy carrying signals without causing extensive losses. The signal conversion or amplification usually generates undesirable thermal losses.

The temperature elevation of the wireless charger transmitter has to be dissipated to minimize thermal conduction by contact to the in-charge device. For safe operation, Lithium-ion batteries must not be charged at temperatures over 40degC. When the battery temperature reaches the maximum allowed level, most wireless charging receivers are programmed to lower the energy transfer to regulate the battery temperature, resulting in extended charging times.

In an embodiment, the shape of the voltage inverter output signal 135 is determined by a toggling sequence of pulses provided by the microcontroller 115 to the voltage inverter.

In order to limit loses in filters 140, power line filter 145 and antenna 150, an embodiment provides a voltage inverter AC output signal 135 which has a power equivalent to the square, the trapezoid signals or a triangle signals, by using a Pulse Width Modulation signal of a frequency f _sw higher than the wireless charger transmitter operating frequency f _op, as shown in Fig. 4A to 4F. The definition of the Pulse Width Modulation signals 430, 440, 450, 460, 470 and 480, match the power of the analog signals 230, 240, 250, 260, 270 and 280. Several pulses and phase durations may produce identical or very similar power at the fundamental frequency f _op. In Fig. 4A to 4F, Pulse Width modulation signal definitions are illustrated as possible examples of signal definitions. However, the person skilled in the art would appreciate that several configurations can be selected. Choosing between signal definition with the same power result is to be done by the designer according to other criteria like, for example, the harmonic signature or the extent of minimum duration pulses as to minimize switching losses. The person skilled in the art would appreciate that these durations can be changed and such changes are within the scope of the invention.

The six

analogue signals

230, 240, 250, 260, 270 and 280 are all part of the trapezoid signal family. They are chosen to illustrate simply the mathematical and physical relationship in the analogue domain between the signal shape and its carried power. When searching for an equivalent Pulse Width Modulation (PWM) signal, there is no need for that signal to mimic the shape of the analogue signal if the frequency signature of that signal is unimportant. It is however of significance that trapezoid signals have electromagnetic signatures that may be convenient for some industries. Any of the trapezoidal signals may be used in embodiments.

Typically, in embodiments, the switching frequency f _sw is chosen as to be an N multiple of the operating frequency f _op. The higher the N factor, the greater the number of possible pulse width modulation combinations and the finer the power steps resolution of the signal of frequency f _op. While there is almost no limit to the size of N, practically, however, the factor N becomes relatively quickly limited by the high power switches and pre-driver technology maximum operation frequency, combined with the inherent losses to switch a signal at such a high frequency f _sw. For the example of N is equal to 160 for an operation frequency f _op at 127.772kHz, the maximum voltage inverter 130 switching frequency f _sw is equal to 20.44352MHz. Switching a power signal at a high frequency f _sw presents challenges on its own that will be addressed below.

In embodiments in which N greater or equal to 16, the resolution needed for 5W wireless charger transmitter can be achieved without the need for an output voltage controlled DC-DC converter 120. For N equal to 24 bits the power resolution is sufficient to control 15W wireless charging transmitter. For N greater than 32, higher power control accuracies are possible than with the output voltage controlled DC-DC converter 120 used in the state of the art solution of Fig. 1A and 1 B. For N is equal or greater than 160, it is possible to accommodate signals that are minimizing electromagnetic interferences and have enough power resolution. The invention, however, is not limited to any specific value of N.

The organization of the Pulse Width modulation can be implemented in several ways. Many of these ways result in creating a DC component in the frequency signature of the signal, thus making them unsuitable. The DC component may be fully filtered by either the wireless charging antenna 150 or the low-pass filter 140 when the latter is present. This leaves two sequence organizations suitable. These are represented in Fig. 5A and 5B. In Fig. 5A and 5B, the sequences have been simplified for visual description clarity. The simplified solutions would be unsuitable to solutions involving electromagnetic interference mitigation.

In an embodiment, the toggling sequences S _pos, and, S _neq, are identical.

Fig. 5A is a graph representing a signal that is positive /negative symmetrical and that generates only the odd frequency harmonics. This signal is generated by driving the voltage inverter 130 with the same signal definition during the positive half period [0, π] and the negative half period [π, 2π] .

In an embodiment, the toggling sequences S _pos, and, S _neq, are reversed, i.e. they are the reverse of each other.

Fig. 5B is a graph representing a signal that is π symmetrical, according to an embodiment. This signal frequency signature will display both even and odd harmonics. Fig. 5B type of signal can be generated by reverse sequencing the signal definition driving the voltage inverter 130 in the [0, π] timeframe to drive the voltage inverter during the second half period [π, 2π] . The signal of Fig. 5B can be of interest since it allows further spreading of the energy along the even harmonics.

In embodiments, toggling sequences are provided by a voltage inverter driver for a voltage inverter. In an embodiment, these toggling sequences are used in the half period in which the respective switches are turned on. In embodiments, the toggling sequences are selected so as to set a power level, by variation of frequency, pulse widths and/or amplitude. In embodiments, the toggling sequences may be selected from a lookup table.

Assuming the signal sequence is of size N, the number of signal sequence combinations is 2 ^N. However, non-symmetrical combinations generate a DC component that makes them unsuitable to the purpose, leaving the number of sequence combinations usable at twice 2 ^N/2 or 2 ^(N/2) +1 less some redundancies generated by combinations where the positive /negative symmetry and the π symmetry are identical. Even for relatively small sequence length N, the number of usable combinations becomes large enough to populate a lookup table with sufficient power steps to control the transmission power of the wireless charger.

Fig. 5C is a table illustrating a lookup table of 512 steps for N equal to 24 bits according to an embodiment. It is realized by listing all 4096 possible sequences excluding the π symmetrical configurations for simplification purposes. For all sequence combinations, a corresponding frequency signature is calculated using the same Fast Fourier Transform tool (Cooley Tukey algorithm) . The normalized amplitude of the fundamental frequency f _sw is then isolated. Assuming the simplifications regarding the voltage inverter 130 loss and the filters, the power of the power transmitter by the wireless charger transmitter is fully proportional to the amplitude of the fundamental frequency f _sw. Power duplicates are then removed leaving a sufficient number of combinations to build a lookup table of 512 nearly linear steps of normalized amplitude associated with their corresponding signal sequence definition. The lookup table is organized either by increasing or decreasing values of the normalized amplitude of the fundamental frequency f _sw. Technically, the transmitted power depends on a certain number of parameters that are not all known by the transmitter, such as misalignment or distance to the receiver resulting in the computed normalized power being irrelevant for the purpose. The correct sequence, increasing or decreasing power, and the resolution steps are the key parameters to care when populating the lookup table. Unlike the state of the art solution using a controlled output voltage DC-DC converter 120, the lookup table is not perfectly linear. However, by increasing N and the number of steps in the lookup table, it is possible to drive the voltage inverter output power with finer resolution than with state of the art solutions, if required.

In Fig. 5C, according to an embodiment, only 12 bits are needed to characterise the signal sequence. These 12 bits correspond to the voltage inverter 130 sequence output during one half period of f _op. The other half period can be determined by the microcontroller 115 by symmetry. Should π symmetrical sequences be used in addition to positive /negative symmetry, an additional bit of characterization is needed bringing it to 13 bits for N equal to 24.

In order to minimize the controller memory size, in embodiments, it is preferable to keep the lookup table as small as possible by leaving the sequence definitions in its shortest possible form. This form may not be directly usable by the various hardware embodiments capable of generating the requested sequence.

Despite being microcontroller friendly, the construction of a pseudo sine or pseudo trapezoid signal using a Pulse Width Modulation presents, in this case, four challenges that are related to the high switching frequency f _sw:

- Inexpensive microcontrollers are clocked at a frequency only a couple of times higher than the frequency f _sw preventing direct control of the Pulse Width Modulation.

- The four signals controlling the voltage inverter 130 power switches 131 to 134 need to be perfectly synchronized to ensure that no short is created between the DC power source 190 and the ground GND.

- According to the Wireless Power Consortium Qi standard version 1.3, a Frequency Shift Keying FSK modulation is to be used to communicate with the in-charge device. This modulation can only be implemented by modulating the frequency f _sw, making it even harder to do with a microcontroller directly controlled Pulse Width Modulation signal.

- Though theoretically achievable, MOSFET technology can be used only with great difficulty above 5MHz due to the switching losses involved. In most cases, the use of Gallium Nitride technology is recommended.

In an embodiment, a charging controller 100 is provided which comprises a voltage inverter driver 110 and a voltage inverter 130. The voltage inverter 130 has output terminals electrically connectable to an inductive wireless charging antenna 150. In Fig. 6a and 6b, the charging controller 100 comprises the voltage inverter driver 110 and the voltage inverter 130. The charging controller is configurable to operate the voltage inverter at a nominal switching frequency f _op. In operation, the nominal switching frequency has an associated period T _op, wherein the period T _op, comprises a first half period T _pos, and a second half period T _neg. The charging controller is configured to supply to the output terminals, in the first half period T _pos: an output signal comprising a sequence S _pos, of pulses at a toggling frequency, f _sw, the pulses alternating between a positive amplitude, V _pos, and an off-state, and in the second half period T _neg an output signal comprising a sequence S _neg, of pulses at a toggling frequency f _sw, the pulses alternating between an off-state (i.e. high impedance state corresponding to an open circuit) and a negative amplitude V _neg, and wherein the toggling frequency f _sw, is a N multiple of the voltage inverter nominal switching frequency f _op, and N is a positive number greater than 1, and wherein the voltage levels V _pos, and V _neg, are of opposite polarity.

A solution to these problems is proposed in the embodiments of Fig. 6A and 6B. Fig. 6A and 6B are schematic diagrams according to embodiments. Modification of the state of the art diagrams shown in Fig. 1A and 1B are illustrated. According to the embodiment of Fig. 6A and 6B, there is provided an H-bridge type voltage inverter driver that is suited to any definition of the voltage inverter 130 output signal 135 using a single frequency f _sw. The sequences S ₁, S ₂, S ₃ and S ₄ allow full control of the wireless charger power signal over the period of f _op using the same resolution N. By adding restrictions on the way the voltage inverter 130 is driven, many topologies of circuits may be suitable to achieve the desired voltage inverter signal output 135. This includes topologies using independent register banks of different sizes N ₁, N ₂, N ₃ and N ₄ operating at different frequencies f _sw1, f _sw2, f _sw3 and f _sw4.

In embodiments, the toggling sequences toggle a voltage level between a level associated with an off state of the respective switch, and a level which is at or greater than a level that turns on the switch.

The voltage inverter driver 110 that controls the voltage inverter 130 to output the Pulse Width Modulation (PWM) signal is described below:

- Two of a pair of n bits shift register sub banks 610-612 and 611-613, each pair being dedicated to the control of 2 switch drivers 620-622 and 621-623.

- The serial output of the n bits shift register 610 is connected in daisy chain to the serial input of the n bits shift register 612 to build a N bits shift register where N is equal to 2 times n corresponding to the resolution of the desired Pulse Width Modulation signal. The output of the n bits shift register 612 is connected to the input of the n bits shift register 610 to form a N bits rotary shift register. Additionally, the serial output of the n bits register bank 610 is used to control the high side switch driver 620 and the serial output of the n bits register bank 612 is used to control the high side switch driver 622.

- In the same way, the serial output of the n bits shift register 611 is connected in daisy chain to the serial input of the n bits shift register 613 to build a N bits shift register where N is equal to 2 times n corresponding to the resolution of the desired Pulse Width Modulation signal. The output of the n bits shift register 613 is connected to the input of the n bits shift register 611 to form a N bits rotary shift register. Additionally, the serial output of the n bits register bank 611 is used to control the low side switch driver 621 and the serial output of the n bits register bank 613 is used to control the low side switch driver 623.

- The microcontroller 115 initializes the n bits shift registers 610 to 613 with sequences of bits S ₂, S ₁, S ₄ and S ₃ respectively, prior to any charging activity. In the example of Fig. 6A, parallel programming was chosen as the simplest possible way using commercially available logic gates. This programming step, to be done at initialisation, will store the desired Pulse Width Modulation signal definition in the N bits register banks.

- The microcontroller 115 also controls the shifting frequency of N bits registers through a clocking system 640 which baseline frequency is the switch frequency f _sw. It is necessary to implement the frequency shift key modulation needed for communication towards the in charge target device 180.

- Each switch driver 620 to 623 is in turn controlling the switch state of the voltage inverter 130 switches 131 to 134.

Fig. 6C and 6D are part schematic and part graphical diagrams illustrating possible N bits shift register bank configurations for generating the expected voltage inverter 130 Pulse Width Modulation (PWM) output signal using the positive /negative symmetry organization described in Fig. 5A. There are several possible sequence combinations S ₁, S ₂, S ₃ and S ₄ for a single N bits signal definition. For an embodiment in which N is equal to 24 and n equal to 12, the simplest option is illustrated in Fig. 6C:

- In the following description, a bit set to 1 turns on the switch and a bit set to 0 turns the switch off.

- The n bits shift

register pair

611 and 613 control the low side switches of the voltage inverter 130. The n bits shift register 611 is initialised by the microcontroller 115 with the hexadecimal 5FAh and the n bits shift register 613 with the hexadecimal value 000h.

- The n bits shift

register pair

610 and 612 control the high side switches of the voltage inverter 130. The n bits shift register 610 is initialised by the microcontroller 115 with the hexadecimal value 000h and the n bits shift register 612 with the hexadecimal value FFFh.

- When the N register shift banks are enabled, the voltage inverter switches are driven as shown in Fig. 6C and generate the voltage inverter output signal 135 (V ₁₃₅) .

In this embodiment, the high side switches 132 and 134 operate the same way as in the state of the art solution. They can consequently use the same switches i.e. MOSFETs, and the same high side MOSFETs drivers. The low side switches, however, are switched at much higher frequencies to generate the requested Pulse Width Modulation signal. These high frequencies are likely, depending on the discretisation factor N, to force the use of switches that can operate at higher frequencies with lower losses and less distorted signal outputs, such as Gallium Nitride FET (GaNFETs) .

A more complex but preferable embodiment is illustrated in Fig. 6D. This solution is technically better for its ability to split the switching losses between the high side and low side switches, reducing the thermal losses caused by switching. It may, for lower values of N, allow the use of MOSFETs for both high side and low side switches:

- The state of the voltage inverter 130 halves is defined by both switch states: should any of the high side or low side switch be off-state, the bridge will be turned off. To be on state, both switches have to be turned on.

- The n bits shift

register pair

611 and 613 controls the low side switches of the voltage inverter 130. The n bits shift register 611 is initialised by the microcontroller 115 with the hexadecimal value 7FEh and the n bits shift register 613 with the hexadecimal value 000h.

- The n bits shift

register pair

610 and 612 controls the high side switches of the H-bridge inverter 130. The n bits shift register 610 is initialised by the microcontroller 115 with the hexadecimal value 000h and the n bits shift register 612 with the hexadecimal value DFBh.

- When the N register shift banks are enabled, the voltage inverter switches are driven as shown in Fig. 6D and generate the voltage inverter output signal 135 (V ₁₃₅) .

The above hexadecimal value of 5FAh is given as a static example of signal reconstruction to illustrate the operation of the configurations illustrated in Fig. 6A and 6B using the voltage inverter control method of Fig. 6C and 6D, according to an embodiment. The same sequence reconstruction method can be used for any value stored in the lookup table of Fig. 5C and in a larger scope, any hexadecimal value with the same number of bits N.

The person skilled in the art will appreciate that the hexadecimal values are provided as an example only and the invention is not limited to these specific values.

Fig. 6E is a flowchart illustrating a power regulation process of the wireless charging transmitter executed by the microcontroller 115 which may be used with any embodiment. Only the steps relevant to the regulation loop are described. For clarity, the essential functions performed by hardware have been left with their corresponding reference of Fig. 3A and Fig. 3B. The method comprises:

- Capturing the DC supply voltage V _DC at step 691.

- Computing, at step 693, a normalized amplitude V _norm using standard electrical circuit calculations. This step may be as simple as:

(for Fig. 3A configuration) Equation 5

- Accessing, at step 694, the lookup table of Fig. 5C (step 695) for the voltage inverter 130 signal output sequence S ₁₃₅ corresponding to the requested power.

- Calculating the switch signal sequences S ₁, S ₂, S ₃ and S ₄ needed to generate S ₁₃₅ at step 696.

- Controlling the voltage inverter 130 using S ₁, S ₂, S ₃ and S ₄ at step 697.

- Radiating by the wireless charger transmitter the power P ₁₅₀ through the wireless charging antenna 150.

- Demodulating the received message by the AM demodulator 160 and returning to step 112, thus closing the regulation loop.

- Responding to the transmitter by accordingly either increasing, decreasing or keeping the same power transmission settings by adjusting the signal output sequence S ₁₃₅.

The step 616, relative to the computation of the signal sequences S ₁, S ₂, S ₃ and S ₄, is optional provided all four sequences S ₁, S ₂, S ₃ and S ₄ are stored as such in the lookup table of Fig. 5C. As already noted in the description of the lookup table, proceeding that way requires significantly more memory resources for the lookup table of Fig. 5C especially for large N configurations of signal. The sequences S ₁, S ₂, S ₃ and S ₄ can be indeed reconstructed easily when knowing the hardware used to generate the signal and the format of the data stored in the lookup table of Fig. 5C.

In an embodiment, the sequence update in step 112 is synchronized with the operation frequency f _op period to avoid a phase shift that may interfere with the frequency modulation communication towards the in-charge device.

To illustrate the embodiment, an example is provided which uses the hardware of Fig. 6A, the control method of the Fig. 6C and the lookup table Fig. 5C. The control method of Fig. 6C implies that the high side switches are operated at f _op. There is consequently no need to address the lookup table to compute the switch driving sequences S ₂ and S ₄ which will alternate the 24 bits complementary sequences FFF000h and 000FFFh respectively.

The lookup table of Fig. 5C stores the output signal S ₁₃₅ in a 12 bit word that represents the output sequence of the voltage inverter during a half period of f _op. When considering only the half bridge, the sequence S ₁₃₅ of 12 bits are used for driving the low side switches during the first and second half-periods by the low side switches. During the other half period, the opposite switch is turned off. Consequently, S1 is driven by sequence 000h appended by the sequence S ₁₃₅ and S ₂ by the complementary sequence S ₁₃₅ appended by the sequence 000h.

Fig. 6F is a flow chart illustrating the process of setting and adjusting the toggling sequences provided by a controller according to an embodiment. The processes may be used with any other embodiment. At 693a, the process comprises selecting, from a plurality of pre-defined sets, an initial set of toggling sequences S ₁, S ₂, S ₃ and S ₄, that provide a power level corresponding to an initial power level. In an embodiment, the initial power level corresponds to the power that is requested by the in-charge device at the start of the charging process. In an embodiment, the toggling sequence may be determined by estimation based on the Fourier series analysis described above. In an embodiment, the estimation may be refined by allowance for non-ideal components. In an embodiment, the toggling sequences may be obtained from a lookup table. In an embodiment, the lookup table may be populated using Fourier analysis as previously described. In an embodiment, the lookup table may be populated by empirical measurement of the power output of toggling sequences.

At 112a, a requested power value is received from an in-charge device and at 112b, a received power is received from the in-charge device. These two values provide information to the controller as to the power level desired by the in-charge device and the actual power being received. This enables the controller to make adjustments where necessary to the toggling sequence and hence change the output power. At 693b, in response to a difference between the requested power and the received power, the controller selects a new toggling sequence providing a power level closer to the requested power level than the initial power value determined by the initial toggling sequence set. In an embodiment, the adjustment is incremental, with the requested power level, or a level close to it, being reached over several iterations.

In an embodiment, there is provided a controller configured to implement the method of Fig. 6F, the controller being connectable to a voltage inverter and the voltage inverter being in turn, connectable to an antenna.

Claims

A charging controller for a wireless charging transmitter, the charging controller comprising a voltage inverter with output terminals electrically connectable to an inductive wireless charging antenna and configurable to operate the voltage inverter at a nominal switching frequency, f _op, the nominal switching frequency having an associated period, T _op, wherein the period, T _op, comprises a first half period, T _pos, and a second half period, T _neg, wherein the charging controller is configured to supply to the output terminals:

in the first half period, T _pos:

an output signal comprising a sequence, S _pos, of pulses at a toggling frequency, f _sw, the pulses alternating between a positive amplitude, V _pos, and an off-state, and

in the second half period, T _neg:

an output signal comprising a sequence, S _neg, of pulses at a toggling frequency, f _sw, the pulses alternating between an off-state and a negative amplitude, V _neg, and

wherein the toggling frequency, f _sw, is amultiple, N, of the voltage inverter nominal

switching frequency, f _op, and, N, is a positive number greater than 1, and wherein the voltage levels, V _pos, and V _neg, are of opposite polarity, and

wherein the charging controller is configured to select, from a plurality of pre-defined sets, an initial set of toggling sequences, S _pos, and, S _neg, that provide a power level corresponding to an initial power level.
A charging controller according to claim 1, configured to provide a voltage inverter output signal alternating the sequences, S _pos, and, S _neq, characterized by the amplitude of the fundamental frequency, f _op, carried power.
A charging controller according to claim 1 or claim 2, further configured to:

receive a requested power value from an in-charge device;

receive a received power value from an in-charge device; and

in response to a difference between the requested power value and the received power value, select new toggling sequences, S _pos, and, S _neq, from the plurality of pre-defined sets, the new toggling sequence providing a power level closer to the requested power level than the initial set.
A charging controller according to any preceding claim, configured to select the toggling sequences, S _pos, and, S _neq, using a lookup table.
A lookup table according to claim 4, associating a plurality of voltage inverter output signal power levels to corresponding sequences, S _pos, and, S _neq, delivering that power level.
A charging controller according to any preceding claim configured to set, N, to be greater than or equal to 24, and optionally greater than or equal to 32, and optionally greater than or equal to 160.
A charging controller according to any preceding claim, configured to provide the toggling sequences such that, S _pos, and, S _neq, are identical or reversed.
A charging controller according to any preceding claim, wherein the voltage inverter is an H-bridge topology voltage inverter.
A charging controller according to claim 1, further comprising an amplitude modulation (AM) demodulator circuit configured to demodulate a load modulated signal sent by an in-charge device and to extract data from the modulated signal.
A charging controller according to claim 1, further comprising a voltage inverter driver to control the voltage inverter output signal and generate, S _pos, and, S _neq, alternating toggling sequences at the toggling frequency, f _sw.
A charging controller according to any preceding claim, wherein the voltage inverter driver further comprises a clocking system configurable to programmably frequency modulate the toggling frequency, f _sw, in polarity and depth.
A charging controller according to any preceding claim, further comprising a microcontroller to control a wireless charging operation by controlling the voltage inverter based on the received data from the in-charge device through the demodulator circuit.
A charging controller for a wireless charging transmitter, the wireless charging transmitter comprising a voltage inverter, wherein the voltage inverter comprises: a first low side switch controllable by a first signal and a first high side switch controllable by a second signal, a second low side switch controllable by a third signal, a second high side switch controllable by a fourth signal and output terminals electrically connectable to an inductive wireless charging antenna and is configurable to operate at a nominal frequency, f _op, the nominal frequency having an associated period, comprising a first half period and a second half period, wherein the charging controller comprises:

a voltage inverter driver,

wherein the voltage inverter driver is configured to

provide:

in the first half period:

the second signal and the third signal at a level associated with an off-state of the respective switches, and

the first signal comprising a first toggling sequence, S ₁, and

the fourth signal comprising a fourth toggling sequence, S ₄, and

in the second half period:

the first signal and the fourth signal at a level associated with an off-state of the respective switches, and

the second signal comprising a second toggling sequence, S ₂, and

the third signal comprising a third toggling sequence, S ₃, and

wherein the charging controller is configured to select, from a plurality of pre-defined sets, an initial set of toggling sequences, S ₁ , S ₂, S ₃, and, S ₄, that provide a power level corresponding to an initial power level.
A charging controller according to claim 13, wherein each toggling sequence comprises toggled on-states and off-states at levels associated respectively with an on-state and an off-state of the respective switches, the first toggling sequence having a first toggling frequency, f _sw1, wherein the first toggling frequency is a multiple by a first multiple, N ₁, of the wireless charger nominal frequency, f _op, the second toggling sequence having a second toggling frequency, f _sw2 wherein the second toggling frequency is a multiple by a second multiple, N ₂, of the wireless charger nominal frequency, f _op, the third toggling sequence having a third toggling frequency, f _sw3, wherein the third toggling frequency is a multiple by a third multiple, N ₃, of the wireless charger nominal frequency, f _op, the fourth toggling sequence having a fourth toggling frequency, f _sw4, wherein the fourth toggling frequency is a multiple by a fourth multiple, N ₄, of the wireless charger nominal frequency, f _op, and

N ₁ , and, N ₄, are positive numbers, and

at least, N ₁, or, N ₄, is greater than 1

and

N ₁, and, N ₄, are positive numbers, and

at least, N ₁ , or, N ₄, is greater than 1.
A charging controller according to claim 13 or claim 14, wherein the voltage inverter driver, further comprises a clocking system configurable to programmably frequency modulate the toggling frequency, f _sw1, f _sw2, f _sw3, and, f _sw4, of the switch control signals S ₁, S ₂, S ₃, and, S ₄, in polarity and depth.
A charging controller according to any of claims 13 to 15, further configured to:

receive a requested power value from a charging device;

receive a received power value from a charging device; and

in response to a difference between the requested power value and the received power value, select a new toggling sequence from the plurality of pre-defined sets, the new toggling sequence providing a power level closer to the requested power level than the initial set.
A charging controller according to any of claims 13 to 16, configured to set, N ₁, N ₂, N ₃, N ₄, such that either, N ₂, and, N ₄, are equal to 1 and, N ₁, is equal to, N ₃, or, N ₁, and, N ₃, are equal to 1 and, N ₂, is equal to, N ₄.
A charging controller according to any of claims 13 to 17, configured to set, N ₁, N ₂, N ₃, N ₄, to an integer, N, corresponding to a required resolution.
A charging controller according to any of claims 13 to 18, configured to select the toggling sequences, S ₁, S ₂, S ₃, and, S ₄, using a look-up table.
A charging controller according to claim 19, wherein the look-up table defines, for each of a plurality of required power levels for energizing the inductive wireless antenna, reconstruction information for reconstructing a respective first toggling sequence, S ₁, a respective second toggling sequence, S ₂, a respective third toggling sequence, S ₃ and a respective fourth toggling sequence, S ₄, wherein each of the respective toggling sequences comprise a sequence of on and off states according to respective predefined frequencies according to the required power level, and wherein the reconstruction information comprises a toggling sequence, S, corresponding to a half period for at least one switch, wherein the half period is a period in which the switch is at a level associated with an on-state of the switch for at least part of the half period, and wherein the voltage inverter driver is configured to:

receive a required power level;

access the look-up table to retrieve the reconstruction information required for reconstructing a first toggling sequence, S ₁, second toggling sequence, S ₂, third toggling sequence, S ₃, and fourth toggling sequence, S ₄, associated with the required power level;

reconstruct, from the reconstruction information, each of respective first reconstructed toggling sequence, S ₁, second reconstructed toggling sequence, S ₂, third reconstructed toggling sequence, S ₃, and fourth reconstructed toggling sequence, S ₄, associated with the required power level; and

supply to the voltage inverter:

a first signal comprising the reconstructed first toggling sequence, S ₁, to the first switch;

a second signal comprising the reconstructed second toggling sequence, S ₂, to the second switch;

a third signal comprising the reconstructed third toggling sequence, S ₃, to the third switch; and

a fourth signal comprising the reconstructed fourth toggling sequence, S ₄, to the fourth switch.
A charging controller according to any of claims 13 to 20, configured to set, N, to be greater than or equal to 24, and optionally greater than or equal to 32, and optionally greater than or equal to 160.
A charging controller according to any of claims 13 to 21, configured to provide the toggling sequences such that, S ₁, and, S ₃, are identical or reversed, and such that, S ₂, and, S ₄, are identical or reversed.
A charging controller according to any of claims 13 to 22, further comprising a microcontroller for controlling a wireless charging operation.
A wireless charging transmitter comprising a controller according to any preceding claim, further comprising:

an inductive wireless charging antenna electrically connected to the output terminals of the voltage inverter; and

a DC power source to supply the controller.
A wireless charger according to claim 13, further comprising a DC-DC converter, configured to receive power from the DC power source at a first voltage and provide power to the voltage inverter at a second voltage, the second voltage being higher than the first voltage.
A wireless charging transmitter according to claim 13 or claim 14, further comprising:

a low-pass or band-rejection filter installed between the voltage inverter and

the inductive wireless charging antenna; and

a Power Line filter installed downstream the DC power source.
A method of operating a charging controller according to any of claims 1 to 12, wherein the method comprises:

selecting, from a plurality of pre-defined sets, an initial set of toggling sequences, S _pos, and, S _neg, that provide a power level corresponding to an initial power level;

providing in the first half period, T _pos:

an output signal comprising the sequence, S _pos, of pulses at a toggling frequency, f _sw, the pulses alternating between a positive amplitude, V _pos, and

an off-state, and

providing in the second half period, T _neg:

an output signal comprising the sequence, S _neg, of pulses at a toggling frequency, f _sw, the pulses alternating between an off-state and a negative amplitude, V _neg,

wherein the toggling frequency, f _sw, is a multiple, N, of the voltage inverter nominal switching frequency, f _op, and, N, is a positive number greater than 1, and wherein the voltage levels, V _pos, and V _neg, are of opposite polarity.
A method of operating a charging controller according to any of claims 13 to 23, the method comprising:

selecting, from a plurality of pre-defined sets, an initial set of toggling sequences, S ₁ , S ₂, S ₃, and, S ₄, that provide a power level corresponding to an initial power level.

providing in the first half period:

the second signal and the third signal at a level associated with an off-state of the respective switches, and

the first signal comprising the first toggling sequence, S ₁, and

the fourth signal comprising the fourth toggling sequence, S ₄, and

providing in the second half period:

the first signal and the fourth signal at a level associated with an off-state of the respective switches, and

the second signal comprising a second toggling sequence, S ₂, and

the third signal comprising a third toggling sequence, S ₃.