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1.发明专利
公开(公告)号：JP2000125561A
公开(公告)日：2000-04-28
申请号：JP28636299
申请日：1999-10-07
Applicant: ST MICROELECTRONICS SRL
Inventor： LIONETTO ANTONIO , OCCHIPINTI LUIGI , SPAMPINATO SERGIO TOMMASO , CAPONETTO RICCARDO
Abstract: PROBLEM TO BE SOLVED: To prevent a burst mode function and, at the same time, to reduce overshooting by modulating the turning-off period of a power switch by using a combinatory function of operating parameters until a limit output voltage condition is reached when mode transition is made from a self-exciting oscillation mode to a fixed oscillator frequency mode. SOLUTION: A primary control loop controls the output voltage Vout of a flyback converter by controlling the voltage Vcs of the self-feeding power of a control circuit by means of an error amplifier Error Amp and a secondary control loop directly controls the output voltage Vout by optically coupling the amplifier Error Amp and control circuit to a Vcomp pin. Then the turning- off period of a power switch is continued until the energy stored in a transformer during the turning-on period of the power switch is completely transferred to an output circuit by operating a bistable circuit LATCH in accordance with the voltage Vcomp compensation capacitor Ccomp through a comparator Ccomp.
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公开(公告)号：DE69810625T2
公开(公告)日：2003-11-27
申请号：DE69810625
申请日：1998-10-07
Applicant: ST MICROELECTRONICS SRL
Inventor： LIONETTO ANTONIO , OCCHIPINTI LUIGI , SPAMPINATO SERGIO TOMMASO , CAPONETTO RICCARDO
Abstract: A method of controlling a flyback DC-DC converter, self-oscillating at steady state conditions, employing a transformer for storing and transferring energy to a load and having an auxiliary winding whose voltage, induced by the current flowing in the secondary winding of the transformer, is monitored to regulate the amount of energy being transferred by way of a primary control loop disabling and enabling the turning on of a power switch driving the primary winding of the transformer and to detect its the zero-crossing and consequently turn on the power switch for a new conduction and energy storage phase, the duration (TON) of which is established by a secondary control loop of the output voltage producing the turning off of the power switch for a new off phase (TOFF), and comprising a fixed frequency oscillator of a frequency lower than the self-oscillating frequency of the converter for start-up charge transient of an output filter capacitor, wherein the power transferred from the primary circuit to the secondary circuit of the flyback transformer is controlled by introducing a delay on the turn-on instant of the power switch in respect to a turn-on command generated, during a self-oscillating functioning phase upon sensing a zero crossing event and during a fixed frequency functioning phase, upon a rising front of the signal generated by said oscillator, in function of input variables of the enabling-disabling primary control loop and of the secondary control loop, regardless of the mode of control.
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公开(公告)号：DE69810625D1
公开(公告)日：2003-02-13
申请号：DE69810625
申请日：1998-10-07
Applicant: ST MICROELECTRONICS SRL
Inventor： LIONETTO ANTONIO , OCCHIPINTI LUIGI , SPAMPINATO SERGIO TOMMASO , CAPONETTO RICCARDO
Abstract: A method of controlling a flyback DC-DC converter, self-oscillating at steady state conditions, employing a transformer for storing and transferring energy to a load and having an auxiliary winding whose voltage, induced by the current flowing in the secondary winding of the transformer, is monitored to regulate the amount of energy being transferred by way of a primary control loop disabling and enabling the turning on of a power switch driving the primary winding of the transformer and to detect its the zero-crossing and consequently turn on the power switch for a new conduction and energy storage phase, the duration (TON) of which is established by a secondary control loop of the output voltage producing the turning off of the power switch for a new off phase (TOFF), and comprising a fixed frequency oscillator of a frequency lower than the self-oscillating frequency of the converter for start-up charge transient of an output filter capacitor, wherein the power transferred from the primary circuit to the secondary circuit of the flyback transformer is controlled by introducing a delay on the turn-on instant of the power switch in respect to a turn-on command generated, during a self-oscillating functioning phase upon sensing a zero crossing event and during a fixed frequency functioning phase, upon a rising front of the signal generated by said oscillator, in function of input variables of the enabling-disabling primary control loop and of the secondary control loop, regardless of the mode of control.
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