# US 8,541,966 B2 · PWM control circuit and PWM control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,541,966 B2 - Document ID: US8541966B2 - Status: Granted - Kind: B2 - Application number: 13/648,621 - Filed: 2012-10-10 - Published: 2013-02-07 - Granted: 2013-09-24 - Earliest claimed: 2007-11-02 - Assignees: Seiko Epson Corporation - Applicants: Seiko Epson Corporation - Inventors: Kesatoshi Takeuchi - Web page: https://patentgrep.com/patent/US8541966B2 ## CPC - H02P 6/16: Circuit arrangements for detecting position - H02P 6/28: Arrangements for controlling current (H02P6/10 takes precedence) - H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS ## Abstract The PWM control circuit includes a polarity determination unit, a full wave rectification unit, an adjustment unit that generates an adjusted waveform signal by adjusting waveform of the full wave rectification signal, and a carrier signal generating unit that generates a fixed frequency carrier signal. The PWM control circuit further includes a comparator that generates an original PWM signal by comparing the adjusted waveform signal and the carrier signal, and a PWM waveform shaping unit that generates a first PWM signal for the positive polarity section and a second PWM signal for the negative polarity section, by shaping the original PWM signal according to the polarity signal. ## Claims ### Claim 1 A PWM control circuit that generates PWM signals based on an analog sensor output from a sensor provided in a device to be controlled, comprising: a polarity determination unit that generates a polarity signal based on positive polarity sections and negative polarity sections of the analog sensor output; a full wave rectification unit that generates a full wave rectification signal by doing full rectification of the analog sensor output; an adjustment unit that generates an adjusted waveform signal based on waveform of the full wave rectification signal; and a PWM waveform shaping unit that generates a first PWM signal for the positive polarity section and a second PWM signal for the negative polarity section, based on the polarity signal and the adjusted waveform signal, wherein the adjusted waveform signal includes a part of the full wave rectification signal and excludes the other part of the full wave rectification signal. ### Claim 2 (depends on 1) The PWM control circuit in accordance with claim 1, wherein when a position at which the polarity of the analog sensor output is reversed is defined as a (n−1)π phase point where n is an integer of at least one, said part of the full wave rectification signal includes a (2n−1)π/2 phase point of the full wave rectification signal. ### Claim 3 (depends on 1) The PWM control circuit in accordance with claim 1, wherein the PWM waveform shaping unit includes: a carrier signal generating unit that generates a fixed frequency carrier signal; and a comparator that generates an original PWM signal by comparing the adjusted waveform signal and the carrier signal. ### Claim 4 (depends on 1) The PWM control circuit in accordance with claim 1, wherein when a position at which the polarity of the analog sensor output is reversed is defined as a (n−1)π phase point where n is an integer of at least one, the valid signal interval setting unit outputs the full wave rectification signal in a symmetrical output section whose center is at a (2n−1)π/2 phase point, and does not output the full wave rectification signal in a symmetrical non-output section whose center is at the (n−1)π phase point. ### Claim 5 (depends on 1) The PWM control circuit in accordance with claim 1, wherein the adjustment unit includes: an offset/gain adjustment unit that adjusts offset and gain of the full wave rectification signal. ### Claim 6 A method of generating PWM signals based on an analog sensor output from a sensor provided in a device to be controlled, comprising: (a) generating a polarity signal based on positive polarity sections and negative polarity sections of the analog sensor output; (b) generating a full wave rectification signal by doing full rectification of the analog sensor output; (c) generating an adjusted waveform signal based on waveform of the full wave rectification signal; and (d) generating a first PWM signal for the positive polarity section and a second PWM signal for the negative polarity section, based on the polarity signal and the adjusted waveform signal, wherein the adjusted waveform signal includes a part of the full wave rectification signal and excludes the other part of the full wave rectification signal. ### Claim 7 (depends on 6) The method according to claim 6, wherein the step (d) includes: generating a fixed frequency carrier signal; and generating an original PWM signal by comparing the adjusted waveform signal and the carrier signal. ### Claim 8 (depends on 6) The method in accordance with claim 6, wherein when a position at which the polarity of the analog sensor output is reversed is defined as a (n−1)π phase point where n is an integer of at least one, said part of the full wave rectification signal includes a (2n−1)π/2 phase point of the full wave rectification signal. ### Claim 9 (depends on 7) The method in accordance with claim 7, wherein when a position at which the polarity of the analog sensor output is reversed is defined as a (n−1)π phase point where n is an integer of at least one, said part of the full wave rectification signal includes a (2n−1)π/2 phase point of the full wave rectification signal. ### Claim 10 A PWM control circuit that generates PWM signals based on an analog sensor output from a sensor provided in a device to be controlled, comprising: a polarity determination unit that generates a polarity signal based on positive polarity sections and negative polarity sections of the analog sensor output; a full wave rectification unit that generates a full wave rectification signal by doing full rectification of the analog sensor output; an adjustment unit that generates an adjusted waveform signal based on waveform of the full wave rectification signal; and a PWM waveform shaping unit that generates a first PWM signal for the positive polarity section and a second PWM signal for the negative polarity section, based on the polarity signal and the adjusted waveform signal, wherein the adjusted waveform signal includes only a part of the full wave rectification signal. ### Claim 11 (depends on 10) The PWM control circuit in accordance with claim 10, wherein when a position at which the polarity of the analog sensor output is reversed is defined as a (n−1)π phase point where n is an integer of at least one, said part of the full wave rectification signal includes a (2n−1)π/2 phase point of the full wave rectification signal. ### Claim 12 (depends on 10) The PWM control circuit in accordance with claim 10, wherein the PWM waveform shaping unit includes: a carrier signal generating unit that generates a fixed frequency carrier signal; and a comparator that generates an original PWM signal by comparing the adjusted waveform signal and the carrier signal. ### Claim 13 (depends on 10) The PWM control circuit in accordance with claim 10, wherein when a position at which the polarity of the analog sensor output is reversed is defined as a (n−1)π phase point where n is an integer of at least one, the valid signal interval setting unit outputs the full wave rectification signal in a symmetrical output section whose center is at a (2n−1)π/2 phase point, and does not output the full wave rectification signal in a symmetrical non-output section whose center is at the (n−1)π phase point. ### Claim 14 (depends on 10) The PWM control circuit in accordance with claim 10, wherein the adjustment unit includes: an offset/gain adjustment unit that adjusts offset and gain of the full wave rectification signal.