# US 10,313,787 B2 · Electromechanical system with predictive back-EMF protection > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,313,787 B2 - Document ID: US10313787B2 - Status: Granted - Kind: B2 - Application number: 14/827,265 - Filed: 2015-08-14 - Published: 2016-02-25 - Granted: 2019-06-04 - Earliest claimed: 2014-08-14 - Assignees: Texas Instruments Incorporated - Applicants: Texas Instruments Incorporated - Inventors: Lars Risbo; Anker Bjørn-Josefsen; Kim N. Madsen - Web page: https://patentgrep.com/patent/US10313787B2 ## CPC - H04R 3/007: {Protection circuits for transducers} - H04R 3/00: Circuits for transducers (arrangements for producing a reverberation or echo sound G10K15/08; amplifiers H03F) - H04R 29/001: {for loudspeakers (H04R29/007 takes precedence)} - H04R 2203/00: Details of circuits for transducers, loudspeakers or microphones covered by H04R3/00 but not provided for in any of its subgroups - H04R: LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS (producing sounds with frequency not determined by supply frequency G10K) ## Abstract A predictive back-emf protection methodology for an electromechanical system, including a signal processor that processes a source signal to provide a modified source signal, a driver that converts the modified source signal to a drive signal, and an electromechanical transducer that generates, from the drive signal, a transducer response, and a back-emf signal coupled back to the driver output. A predictive back-emf generator (such as a routine in the signal processor) is characterized by a back-emf transfer function (linear parameterized model of the electromechanical transducer) for transforming an input signal into a transform back-emf representation of a back-emf signal predicted by the back-emf transfer function as a response of the electromechanical transducer to such input signal. The signal processor processes the source signal based on the transform back-emf representation to generate the modified source signal input to the driver. An example application is limiting peaking current in an audio system. ## Claims ### Claim 1 An electromechanical system that generates back-emf (electro-motive force), comprising a signal source to provide a source signal; a signal driver receiving an input signal based on a modified source signal, and generating a drive signal; an electromechanical transducer coupled to receive the drive signal, and to generate a transducer output response, and a back-emf signal response; the signal driver including: an signal processing module to receive the source signal, and to generate the modified source signal; an amplifier to receive the modified source signal, and to generate the drive signal, the amplifier having a pre-defined output peak current limit; the signal processing module including: a predictive back-emf generator; a peak current limit control loop including the predictive back-emf generator to generate the modified source signal based on: the source signal, and a feedback predictive back-emf signal, and a peak current reference corresponding to the pre-defined output peak current limit, and the predictive back-emf generator to generate the predictive back-emf signal based on a pre-defined back-emf transfer function as a representation of the back-emf response of the electromechanical transducer to the modified source signal. ### Claim 2 (depends on 1) The system of claim 1, wherein the signal processing module including the predictive back-emf generator comprises a routine executed by a digital signal processor. ### Claim 3 (depends on 1) The system of claim 1, wherein the signal source is an audio signal source; and the electromechanical transducer is an audio speaker, where the transducer response is audio signals generated by the audio speaker. ### Claim 4 (depends on 1) The system of claim 1, wherein the back-emf transfer function is based on a linearized parameterized model of the electromechanical transducer. ### Claim 5 (depends on 1) The system of claim 1, wherein the peak current limit control loop operates in a voltage domain, with the predictive back-emf signal and the pre-defined output peak current limit corresponding to currents expressed in the voltage domain. ### Claim 6 (depends on 1) The system of claim 1, wherein based on the modified source signal, the signal driver generates the drive signal so that the amplifier does not exceed the pre-defined output peak current limit. ### Claim 7 A signal driver circuit for use in a system with a signal source to generate a source signal, and an electromechanical transducer to generate, in response to a drive signal based on the source signal, a transducer output response, and a back-emf signal response, the circuit comprising: a signal processing module to receive the source signal, and to generate a modified source signal; an amplifier to receive the modified source signal, and to generate the drive signal, the amplifier having a pre-defined output peak current limit; the signal processing module including: a predictive back-emf generator; a peak current limit control loop including the predictive back-emf generator to generate the modified source signal based on: the source signal, and a feedback predictive back-emf signal, and a peak current reference corresponding to the pre-defined output peak current limit, and the predictive back-emf generator to generate the predictive back-emf signal based on a pre-defined back-emf transfer function as a representation of the back-emf response of the electromechanical transducer to the modified source signal. ### Claim 8 (depends on 7) The circuit of claim 7, wherein the signal processing module including the predictive back-emf generator comprises a routine executed by a digital signal processor. ### Claim 9 (depends on 7) The circuit of claim 7, wherein the signal source is an audio signal source; and the electromechanical transducer is an audio speaker, where the transducer response is audio signals generated by the audio speaker. ### Claim 10 (depends on 7) The system of claim 7, wherein the back-emf transfer function is based on a linearized parameterized model of the electromechanical transducer. ### Claim 11 (depends on 7) The circuit of claim 7, wherein the peak current limit control loop operates in a voltage domain, with the predictive back-emf signal and the pre-defined output peak current limit corresponding to currents expressed in the voltage domain. ### Claim 12 (depends on 7) The circuit of claim 7, wherein based on the modified source signal, the signal driver generates the drive signal so that the amplifier does not exceed the pre-defined output peak current limit. ### Claim 13 A signal processor for use in a system with a signal source to generate a source signal, a signal driver including an amplifier to generate a drive signal based on the source signal, and an electromechanical transducer to generate, in response to the drive signal, a transducer output response, and a back-emf signal response, the signal processor comprising: a predictive back-emf generator; a peak current limit control loop including the predictive back-emf generator to generate the modified source signal based on: the source signal, and a feedback predictive back-emf signal, and a peak current reference corresponding to a pre-defined output peak current limit of the amplifier; the predictive back-emf generator to generate the predictive back-emf signal based on a pre-defined back-emf transfer function as a representation of the back-emf response of the electromechanical transducer to a modified source signal for input to the signal driver. ### Claim 14 (depends on 13) The signal processor of claim 13, wherein the signal processor including the predictive back-emf generator comprises a routine executed by a digital signal processor. ### Claim 15 (depends on 13) The signal processor of claim 13, wherein the signal source is an audio signal source; and the electromechanical transducer is an audio speaker, where the transducer response is audio signals generated by the audio speaker. ### Claim 16 (depends on 13) The signal processor of claim 13, wherein the back-emf transfer function is based on a linearized parameterized model of the electromechanical transducer. ### Claim 17 (depends on 13) The signal processor of claim 13, wherein the peak current limit control loop operates in a voltage domain, with the predictive back-emf signal and the pre-defined output peak current limit corresponding to currents expressed in the voltage domain. ### Claim 18 (depends on 13) The signal processor of claim 13, wherein based on the modified source signal, the signal driver generates the drive signal so that the amplifier does not exceed the pre-defined output peak current limit.