# US 10,374,519 B2 · LLC resonant converter and method for suppressing ripples in output voltage thereof > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,374,519 B2 - Document ID: US10374519B2 - Status: Granted - Kind: B2 - Application number: 15/185,718 - Filed: 2016-06-17 - Published: 2016-12-22 - Granted: 2019-08-06 - Earliest claimed: 2015-06-17 - Assignees: Astec International Limited - Applicants: Astec International Limited - Inventors: Shi Jie Deng; Qing Feng Liu; Guang Quan Li; Zhao Fu Zhou; Zhao Tu Fan - Web page: https://patentgrep.com/patent/US10374519B2 ## CPC - H02M 3/3376: {with automatic control of output voltage or current} - H02M 1/0022: {the disturbance parameters being input voltage fluctuations} - H02M 1/0058: {by employing soft switching techniques, i.e. commutation of transistors when applied voltage is zero or when current flow is zero (using an auxiliary actively switched resonant commutation circuit connected to an intermediate DC voltage or between two push-pull branches of an inverter bridge H02M7/4811; in resonant inverters H02M7/4815; in inverters operating from a resonant DC source H02M7/4826)} - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - Y02P 80/10: Efficient use of energy, e.g. using compressed air or pressurized fluid as energy carrier - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The present disclosure discloses an LLC resonant converter and a method for suppressing ripples in output voltage of the LLC resonant converter. The LLC resonant converter comprises: a half-bridge or full-bridge chopper having a driving circuit, an inductance-capacitance series resonant network coupled to the chopper, an isolation transformer coupled to the resonant network, and a rectification and filtering circuit coupled to the isolation transformer; a feedforward controller coupled to generate a feedforward signal based on an input voltage; and a controlled oscillator coupled to receive the feedforward signal from the feedforward controller and to control an operating frequency of the chopper via the driving circuit based on the feedforward signal. Thus, a feedforward correction is provided for the LLC resonant converter, so that ripples in a DC output voltage of the LLC resonant converter are reduced. ## Claims ### Claim 1 An LLC resonant converter, comprising: a half-bridge or full-bridge chopper having a driving circuit; an inductance-capacitance series resonant network coupled to the chopper; an isolation transformer coupled to the resonant network; a rectification and filtering circuit coupled to the isolation transformer; a linear proportional feedforward controller comprising at least one of a low-pass filter and a band-pass filter coupled to generate a feedforward signal based on an input voltage; and a controlled oscillator coupled to receive the feedforward signal from the feedforward controller and to control an operating frequency of the chopper via the driving circuit based on the feedforward signal. ### Claim 2 (depends on 1) The LLC resonant converter according to claim 1, further comprising: a feedback controller coupled to generate a feedback signal based on an output error voltage of the LLC resonant converter; wherein the controlled oscillator is coupled to receive the feedback signal and the feedforward signal to control the operating frequency of the chopper via the driving circuit. ### Claim 3 (depends on 2) The LLC resonant converter according to claim 2, wherein the feedforward signal and the feedback signal are summed at an input side of the controlled oscillator. ### Claim 4 (depends on 2) The LLC resonant converter according to claim 2, wherein the feedforward controller, the feedback controller and/or the controlled oscillator are implemented by an analog circuit, or by a discrete circuit that is based on an equivalent or approximate transformation. ### Claim 5 (depends on 1) The LLC resonant converter according to claim 1, wherein the feedforward controller comprises the low-pass filter. ### Claim 6 (depends on 5) The LLC resonant converter according to claim 5, wherein a transfer function of the low-pass filter satisfies the following equation: G ⁢ ⁢ 7 ⁢ ( s ) = Ke · ω ⁢ ⁢ n s + ω ⁢ ⁢ n where Ke represents a filter coefficient of the low-pass filter, ωn represents an ripple angular frequency, and s represents an argument of Laplace transformation. ### Claim 7 (depends on 1) The LLC resonant converter according to claim 1, wherein the feedforward controller comprises the band-pass filter. ### Claim 8 (depends on 7) The LLC resonant converter according to claim 7, wherein a transfer function of the band-pass filter satisfies the following equation: G ⁢ ⁢ 7 ⁢ ( s ) = Ke · 2 · ξ · ω ⁢ ⁢ n · s s 2 + 2 · ξ · ω ⁢ ⁢ n · s + ω ⁢ ⁢ n 2 where Ke represents a filter coefficient of the band-pass filter, ωn represents a natural oscillation angular frequency, s represents an argument of Laplace transformation, and ξ represents a damping coefficient. ### Claim 9 A method for suppressing ripples in an output voltage of an LLC resonant converter, the LLC resonant converter comprising a half-bridge or full-bridge chopper having a driving circuit, an inductance-capacitance series resonant network coupled to the chopper, an isolation transformer coupled to the resonant network, and a rectification and filtering circuit coupled to the isolation transformer, the method comprising: generating, by a linear proportional feedforward controller comprising at least one of a low-pass filter and a band-pass filter, a feedforward signal based on an input voltage; and controlling, by a controlled oscillator, an operating frequency of the chopper based on the feedforward signal. ### Claim 10 (depends on 9) The method according to claim 9, wherein the filter has a band-pass filtering characteristic. ### Claim 11 (depends on 10) The method according to claim 10, wherein the filter is implemented by an analog circuit, or by a discrete circuit that is based on an equivalent or approximate transformation. ### Claim 12 A method for suppressing ripples in an output voltage of an LLC resonant converter, the LLC resonant converter comprising a half-bridge or full-bridge chopper having a driving circuit, an inductance-capacitance series resonant network coupled to the chopper, an isolation transformer coupled to the resonant network, and a rectification and filtering circuit coupled to the isolation transformer, the method comprising: generating, by a linear proportional feedforward controller comprising at least one of a low-pass filter and a band-pass filter, a feedforward signal based on an input voltage; generating a feedback signal based on an output error voltage of the LLC resonant converter; generating a control signal by summing the feedback signal and the feedforward signal; and controlling, by a controlled oscillator, an operating frequency of the chopper based on the control signal. ### Claim 13 (depends on 12) The method according to claim 12, wherein the filter has a low-pass filtering characteristic. ### Claim 14 (depends on 13) The method according to claim 13, wherein the filter is implemented by an analog circuit, or by a discrete circuit that is based on an equivalent or approximate transformation.