Bidirectional communication demodulation for wireless charging system
First Claim
1. In a wireless charging system comprising a power transmitter and a power receiver, wherein a primary coil in the power transmitter wirelessly transmits a power signal to a secondary coil in the power receiver, a method implemented by one of the power transmitter and the power receiver for recovering binary data modulated on the power signal using a bi-phase digital encoding scheme, the method comprising:
- (a) scaling an analog signal corresponding to voltage in a first coil of the wireless charging system using analog circuitry to generate a processed analog signal as a scaled-down waveform, wherein the first coil is one of the primary coil and the secondary coil;
(b) periodically sampling the processed analog signal at expected times of occurrences of voltage peaks in the scaled-down waveform using an analog-to-digital converter triggered by a pulse-width modulator to generate a sequence of digital samples;
(c) detecting transitions in the sequence of digital samples associated with the bi-phase digital encoding scheme by applying two or more different transition-detection filters to the sequence of digital samples; and
(d) decoding the detected transitions to recover the binary data.
5 Assignments
0 Petitions
Accused Products
Abstract
A system and method for demodulating a wireless power signal onto which binary data has been modulated involves processing the wireless power signal with analog circuitry to produce a modified power signal in accordance with the type of demodulation used, periodically capturing digital samples of the modified power signal to produce a series of digital samples, applying, with an MCU, at least two digital filtering algorithms to the digital samples to determine transitions associated with the modulation, and recovering, with the MCU, the binary data as a function of the determined transitions. The demodulator is applicable to bidirectional power transfer capable devices and includes algorithms that can be applied similarly to both ASK and FSK demodulations with little or no modification.
-
Citations
17 Claims
-
1. In a wireless charging system comprising a power transmitter and a power receiver, wherein a primary coil in the power transmitter wirelessly transmits a power signal to a secondary coil in the power receiver, a method implemented by one of the power transmitter and the power receiver for recovering binary data modulated on the power signal using a bi-phase digital encoding scheme, the method comprising:
-
(a) scaling an analog signal corresponding to voltage in a first coil of the wireless charging system using analog circuitry to generate a processed analog signal as a scaled-down waveform, wherein the first coil is one of the primary coil and the secondary coil; (b) periodically sampling the processed analog signal at expected times of occurrences of voltage peaks in the scaled-down waveform using an analog-to-digital converter triggered by a pulse-width modulator to generate a sequence of digital samples; (c) detecting transitions in the sequence of digital samples associated with the bi-phase digital encoding scheme by applying two or more different transition-detection filters to the sequence of digital samples; and (d) decoding the detected transitions to recover the binary data. - View Dependent Claims (2, 3, 4, 5, 6, 15, 16, 17)
-
-
7. In a wireless charging system comprising a power transmitter and a power receiver, wherein a primary coil in the power transmitter wirelessly transmits a power signal to a secondary coil in the power receiver, a method implemented by one of the power transmitter and the power receiver for recovering binary data modulated on the power signal using a bi-phase digital encoding scheme, the method comprising:
-
(a) processing an analog signal corresponding to voltage in a first coil of the wireless charging system using analog circuitry to generate a processed analog signal, wherein the first coil is one of the primary coil and the secondary coil; (b) sampling the processed analog signal to generate a sequence of digital samples; (c) detecting transitions in the sequence of digital samples associated with the bi-phase digital encoding scheme by applying two or more different transition-detection filters to the sequence of digital samples; and (d) decoding the detected transitions to recover the binary data, wherein the two or more different transition-detection filters comprise two or more of; a first transition-detection filter algorithm comprising detecting a transition only if amplitudes of the digital samples are determined to correspond to expected sample amplitudes; a second transition-detection filter algorithm comprising; (A1) calculating a first average of a first N of the digital samples, N>
1;(A2) calculating a second average of a subsequent N of the digital samples; (A3) calculating a first difference between the first and second averages; and (A4) detecting a first transition candidate when the magnitude of the difference exceeds a first specified threshold value; a third transition-detection filter algorithm comprising; (C1) detecting a valid low-to-high transition only if a most-recent bit 0 in the binary data was encoded at a high sample level; and (C2) detecting a valid high-to-low transition only if the most-recent bit 0 in the binary data was encoded at a low sample level; a fourth transition-detection filter algorithm comprising; (B1) calculating a first weighted average using a first set of the digital samples corresponding to a sliding window; (B2) calculating a second weighted average using a second set of the digital samples corresponding to the sliding window; (B3) calculating a second difference between the first and second weighted averages; and (B4) detecting a second transition candidate when the magnitude of the second difference exceeds a second specified threshold value; and a fifth transition-detection filter algorithm comprising detecting a transition only if timing of the transition is determined to correspond to an expected transition time. - View Dependent Claims (8, 9, 10, 11, 12)
-
-
13. In a wireless charging system comprising a power transmitter and a power receiver, wherein a primary coil in the power transmitter wirelessly transmits a power signal to a secondary coil in the power receiver, a method implemented by one of the power transmitter and the power receiver for recovering binary data modulated on the power signal using a bi-phase digital encoding scheme, the method comprising:
-
(a) processing an analog signal corresponding to voltage in a first coil of the wireless charging system using analog circuitry to generate a processed analog signal, wherein the first coil is one of the primary coil and the secondary coil; (b) sampling the processed analog signal to generate a sequence of digital samples; (c) detecting transitions in the sequence of digital samples associated with the bi-phase digital encoding scheme by applying two or more different transition-detection filters to the sequence of digital samples; and (d) decoding the detected transitions to recover the binary data, wherein step (b) comprises; periodically sampling the processed analog signal at a sequence of sampling times separated by a normal sampling interval corresponding to an integer multiple of a cycle of the processed analog signal; and the sampling times are based on results of a calibration process in which the processed analog signal is sampled at calibration sampling times separated by a calibration sampling interval that is different from the normal sampling interval to generate a sequence of calibration samples that approximates samples generated by sampling the processed analog signal multiple times over a single cycle of the processed analog signal. - View Dependent Claims (14)
-
Specification