Patents by Inventor Kim-Ly Kha
Kim-Ly Kha has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 11750097Abstract: A switch-mode AC-DC power converter includes a pair of input terminals, a pair of output terminals, and four switches coupled in a bridgeless totem-pole circuit arrangement between the pair of input terminals and the pair of output terminals. A control circuit is coupled to the four switches and configured to, during a cycle of an AC voltage input, turn on the first switch, turn off the second switch, and apply pulse-width modulation (PWM) control signals to the third and fourth switches. The control circuit is also configured to, during a zero crossing of the AC voltage input, supply a PWM control signal to the fourth switch to reduce a rate of voltage change across the second switch at the zero crossing to reduce common mode noise of the power converter.Type: GrantFiled: November 4, 2021Date of Patent: September 5, 2023Assignee: Astec International LimitedInventors: Zhihua Gu, Siu Chik Wong, Kim Ly Kha
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Publication number: 20230155486Abstract: A multi-phase interleaved PFC converter includes at least six switches coupled in a multi-phase interleaved circuit arrangement, and a control circuit. The control circuit is configured to turn on and turn off a first one of the switches according to a PWM signal to operate the first switch as an active switch having an off-time as a function of a duty cycle of the PWM signal, while turning on and turning off a second one of the switches as a synchronous switch. The control circuit is also configured to receive signal(s) indicative of currents in each phase of the interleaved circuit arrangement, set an on-time of the second switch equal to the off-time of the first switch when the signal(s) indicate continuous mode operation, and set the on-time of the second switch to a duration less than the off-time of the first switch when the signal(s) indicate discontinuous mode operation.Type: ApplicationFiled: January 17, 2023Publication date: May 18, 2023Inventors: Zhihua GU, Siu Chik WONG, Kim Ly KHA
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Patent number: 11557961Abstract: A multi-phase interleaved PFC converter includes at least six switches coupled in a multi-phase interleaved circuit arrangement, and a control circuit. The control circuit is configured to turn on and turn off a first one of the switches according to a PWM signal to operate the first switch as an active switch having an off-time as a function of a duty cycle of the PWM signal, while turning on and turning off a second one of the switches as a synchronous switch. The control circuit is also configured to receive signal(s) indicative of currents in each phase of the interleaved circuit arrangement, set an on-time of the second switch equal to the off-time of the first switch when the signal(s) indicate continuous mode operation, and set the on-time of the second switch to a duration less than the off-time of the first switch when the signal(s) indicate discontinuous mode operation.Type: GrantFiled: January 20, 2020Date of Patent: January 17, 2023Assignee: Astec International LimitedInventors: Zhihua Gu, Siu Chik Wong, Kim Ly Kha
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Publication number: 20220060112Abstract: A switch-mode AC-DC power converter includes a pair of input terminals, a pair of output terminals, and four switches coupled in a bridgeless totem-pole circuit arrangement between the pair of input terminals and the pair of output terminals. A control circuit is coupled to the four switches and configured to, during a cycle of an AC voltage input, turn on the first switch, turn off the second switch, and apply pulse-width modulation (PWM) control signals to the third and fourth switches. The control circuit is also configured to, during a zero crossing of the AC voltage input, supply a PWM control signal to the fourth switch to reduce a rate of voltage change across the second switch at the zero crossing to reduce common mode noise of the power converter.Type: ApplicationFiled: November 4, 2021Publication date: February 24, 2022Inventors: Zhihua Gu, Siu Chik Wong, Kim Ly Kha
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Patent number: 11183932Abstract: A switch-mode AC-DC power converter includes a pair of input terminals, a pair of output terminals, and four switches coupled in a bridgeless totem-pole circuit arrangement between the pair of input terminals and the pair of output terminals. A control circuit is coupled to the four switches and configured to, during a cycle of an AC voltage input, turn on the first switch, turn off the second switch, and apply pulse-width modulation (PWM) control signals to the third and fourth switches. The control circuit is also configured to, during a zero crossing of the AC voltage input, supply a PWM control signal to the fourth switch to reduce a rate of voltage change across the second switch at the zero crossing to reduce common mode noise of the power converter.Type: GrantFiled: January 8, 2020Date of Patent: November 23, 2021Assignee: Astec International LimitedInventors: Zhihua Gu, Siu Chik Wong, Kim Ly Kha
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Publication number: 20210226528Abstract: A multi-phase interleaved PFC converter includes at least six switches coupled in a multi-phase interleaved circuit arrangement, and a control circuit. The control circuit is configured to turn on and turn off a first one of the switches according to a PWM signal to operate the first switch as an active switch having an off-time as a function of a duty cycle of the PWM signal, while turning on and turning off a second one of the switches as a synchronous switch. The control circuit is also configured to receive signal(s) indicative of currents in each phase of the interleaved circuit arrangement, set an on-time of the second switch equal to the off-time of the first switch when the signal(s) indicate continuous mode operation, and set the on-time of the second switch to a duration less than the off-time of the first switch when the signal(s) indicate discontinuous mode operation.Type: ApplicationFiled: January 20, 2020Publication date: July 22, 2021Inventors: Zhihua GU, Siu Chik WONG, Kim Ly KHA
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Publication number: 20210211049Abstract: A switch-mode AC-DC power converter includes a pair of input terminals, a pair of output terminals, and four switches coupled in a bridgeless totem-pole circuit arrangement between the pair of input terminals and the pair of output terminals. A control circuit is coupled to the four switches and configured to, during a cycle of an AC voltage input, turn on the first switch, turn off the second switch, and apply pulse-width modulation (PWM) control signals to the third and fourth switches. The control circuit is also configured to, during a zero crossing of the AC voltage input, supply a PWM control signal to the fourth switch to reduce a rate of voltage change across the second switch at the zero crossing to reduce common mode noise of the power converter.Type: ApplicationFiled: January 8, 2020Publication date: July 8, 2021Inventors: Zhihua GU, Siu Chik WONG, Kim Ly KHA
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Patent number: 10122207Abstract: According to some aspects of the present disclosure, automatic transfer switch circuits and control methods are disclosed. Example automatic transfer switch circuits include a first voltage input having a line terminal and a neutral terminal, a second voltage input having a line terminal and a neutral terminal, a voltage output having a line output terminal and a neutral output terminal, a first relay coupled to the line terminal of the first voltage input and the line terminal of the second voltage input, a second relay coupled to the neutral terminal of the first voltage input and the neutral terminal of the second voltage input, a third relay coupled between the line output terminal and at least one of the first relay and second relay, a fourth relay coupled between the neutral output terminal and at least one of the first relay and the second relay, and a controller.Type: GrantFiled: August 30, 2016Date of Patent: November 6, 2018Assignee: Astec International LimitedInventors: Kim Ly Kha, Lei Shi
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Patent number: 9979307Abstract: Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.Type: GrantFiled: January 10, 2014Date of Patent: May 22, 2018Assignee: ASTEC INTERNATIONAL LIMITEDInventor: Kim Ly Kha
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Publication number: 20180062426Abstract: According to some aspects of the present disclosure, automatic transfer switch circuits and control methods are disclosed. Example automatic transfer switch circuits include a first voltage input having a line terminal and a neutral terminal, a second voltage input having a line terminal and a neutral terminal, a voltage output having a line output terminal and a neutral output terminal, a first relay coupled to the line terminal of the first voltage input and the line terminal of the second voltage input, a second relay coupled to the neutral terminal of the first voltage input and the neutral terminal of the second voltage input, a third relay coupled between the line output terminal and at least one of the first relay and second relay, a fourth relay coupled between the neutral output terminal and at least one of the first relay and the second relay, and a controller.Type: ApplicationFiled: August 30, 2016Publication date: March 1, 2018Inventors: Kim Ly KHA, Lei SHI
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Patent number: 9866133Abstract: Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.Type: GrantFiled: January 10, 2014Date of Patent: January 9, 2018Assignee: ASTEC INTERNATIONAL LIMITEDInventor: Kim Ly Kha
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Patent number: 9866134Abstract: Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.Type: GrantFiled: January 10, 2014Date of Patent: January 9, 2018Assignee: ASTEC INTERNATIONAL LIMITEDInventor: Kim Ly Kha
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Publication number: 20150200598Abstract: Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.Type: ApplicationFiled: January 10, 2014Publication date: July 16, 2015Applicant: Astec International LimitedInventor: Kim Ly Kha
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Publication number: 20150200597Abstract: Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.Type: ApplicationFiled: January 10, 2014Publication date: July 16, 2015Applicant: Astec International LimitedInventor: Kim Ly Kha
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Publication number: 20150200596Abstract: Methods of regulating an output voltage of a switched mode power supply having a variable input voltage and a power switch include adjusting a reference voltage to adjust a duty cycle of a control signal for the power switch. The reference voltage may be adjusted as a function of the duty cycle, in response to the duty cycle of the control signal being outside a defined range and/or in the response to a temperature within the switched mode power supply being above a threshold temperature. Other methods include selecting a reference voltage from a plurality of reference voltages based on a determined input voltage and generating a control signal for the power switch as a function of the selected reference voltage to adjust the duty cycle of the control signal. Switched mode power supplies and control circuits for implementing the methods are also disclosed.Type: ApplicationFiled: January 10, 2014Publication date: July 16, 2015Applicant: Astec International LimitedInventor: Kim Ly Kha
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Patent number: 5892652Abstract: This invention concerns a sensitive key device with capacitive effect working through an electrically insulating plate, the key being supported by a printed circuit board. According to the invention, the bottom of a single part having a spring blade made of an electrically conducting material is fixed to the printed circuit board. The top (11) of this part forms a detection surface designed to be placed in contact with the transparent plate. The center of the part makes the part flexible such that the detection surface is in elastic contact with the plate, regardless of parallelism defects between this plate and the printed circuit board.Type: GrantFiled: December 19, 1996Date of Patent: April 6, 1999Assignee: Compagnie Europeenne pour l'Equipement Menager-CepemInventors: Jean-Michel Bony, Fabrice Frappereau, Kim Ly Kha, Jean-Pierre Nugeyre
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Patent number: 5448469Abstract: A switch mode power supply includes a transformer and a switching transistor for turning the primary of the transformer on and off. The secondary of the transformer is connected to a comparator which compares the output voltage to a reference voltage and provides a reverse current to the switching transistor to control the duty cycle of the switching transistor in accordance with the comparison.Type: GrantFiled: March 9, 1994Date of Patent: September 5, 1995Assignee: Deutsche Thomson-Brandt GmbHInventors: Gerard Rilly, Jose Rodriquez-Duran, Kim-Ly Kha