Abstract: A power conversion apparatus includes a comparison circuit which compares a determination element related to a loss in the power converter with a switching reference value and outputs a determination instruction when a difference has occurred between them, a determination circuit which outputs a two-level operation switching instruction when the determination element is greater than or equal to the switching reference value, and a switching circuit which, when having received a two-level operation switching instruction, turns off the alternating-current switch and turns on the valve devices in the arm sequentially, thereby bringing the power converter into a two-level operation state.

Abstract: A protection circuit includes a first switch, a second switch and a third switch. The first switch, the second switch and the third switch are configured to generate lock signals indicative of an electrical voltage transition on the respective phases of a multi-phase power signal. A control circuit is configured to prevent the first switch from changing state if the second switch or third switch is changing state.

Abstract: Disclosed are various embodiments of resonant power management of a mobile device. In one embodiment, a mobile device including a power management unit (PMU) including a resonant inverter, a plurality of AC/DC converters, and an AC bus configured to route the AC power from the resonant inverter to the plurality of AC/DC converters. The resonant inverter converts DC power from a power source to AC power that is converted to DC power by the AC/DC converters and supplied to loads of the mobile device. In another embodiment, a method for power management of a mobile device includes monitoring, by a PMU of the mobile device, an operating mode of the mobile device and adjusting an output frequency of a resonant inverter of an AC power distribution network of the PMU in response to a change in the operating mode of the mobile device.

Abstract: An electrode pattern is arranged near an output pattern, a leakage current leaked from the output pattern is detected by a leakage-current detection circuit via the electrode pattern, and a light emitting diode is driven based on a detection result of the leakage-current detection circuit, thereby notifying an operation state of an inverter.

Abstract: An exemplary embodiment of a flyback power converter includes a transformer for power transfer, a high-side transistor, a low-side transistor, two diodes, a control circuit, and a high-side drive circuit. The high-side transistor and the low-side transistor are coupled to switch the transformer. The two diodes are coupled to said transformer to circulate energy of leakage inductance of the transformer to an input power rail of the power converter. The control circuit generates a switching signal coupled to control the high-side transistor and the low-side transistor. The high-side drive circuit is coupled to receive the switching signal for driving the high-side transistor. The transformer has an auxiliary winding generating a floating power to provide power supply for said high-side drive circuit.

Abstract: Switching converter systems are provided to control output voltage across a load by means of a converter forward path and a converter feedback path. The forward path preferably includes a transistor, an inductive element, a diode and a capacitor arranged to switchably exchange energy with the capacitor to thereby generate the output voltage. The feedback path preferably extends from the capacitor and is configured to digitally control a duty cycle of the transistor in response to the output voltage.

Abstract: An inverter control circuit (6) controls the operation of a plurality of switching elements in a three-phase inverter circuit (2) by a PWM signal. A phase voltage output from the three-phase inverter circuit (2) is outputted through a low-pass filter (3). A waveform of the phase voltage output from the low-pass filter (3) assumes the following waveforms through the control of the PWM signal. The waveform becomes zero in a first one-third period of a cycle; forms a sine wave corresponding to a phase from 0 to 2?/3 in a second one-third period; and forms a sine wave corresponding to a phase from ?/3 to ? in a remaining one-third period of the cycle. Such PWM signal cyclically includes a period where a pulse is not generated. Therefore, the switching action of the switching element is periodically stopped.

Abstract: This invention relates to SMPS controllers employing primary side sensing. We describe a system for identifying a knee point in a sensing waveform, at which the output voltage of the SMPS may be sampled accurately on the primary side. The system identifies the knee point, broadly speaking, by tracking a portion of a power transformer voltage waveform, and samples the voltage waveform at the knee point to determine the SMPS output voltage. In preferred embodiments this technique is implemented using a circuit akin to a decaying peak detector, providing a timing signal indicating detection of the knee point. Sample/hold and error amplifier circuits may be employed to achieve output voltage regulation.

Abstract: In a method for optimizing a space vector pulse width modulation, a voltage is connected to a load, by combining discrete switching states of a plurality of switches to control the load, the load being switched to zero potential by two of the switching states. In the case the maximum degree of control is increased, during a pulse width modulation period, at least one of the switching states, that switches to zero potential, is omitted.

Abstract: A power conversion system for providing power to an electrical grid is described. The system includes a power converter coupled to a direct current (DC) power source. The system also includes a contactor coupled to the power converter and the electrical grid and configured to selectively electrically couple the power converter to the electrical grid. The system also includes a system controller communicatively coupled to the power converter and the contactor and configured to close the contactor to electrically couple the power converter to the electrical grid and to activate the power converter when a DC voltage provided has remained higher than a voltage level for a length of time. The system controller is also configured to deactivate the power converter, while the contactor is maintained in the closed position, when an alternating current (AC) power output has remained lower than a power level for a length of time.

Abstract: A method and apparatus of reducing peak current variation with changing input line voltage in a switch mode power supply is disclosed. An example method includes sensing a current through a switching device of the switch mode power supply. A variable current limit threshold is generated, which increases from a first level to a second level during an on time of the switching device. The current is compared to the variable current limit threshold. A feedback signal representative of an output voltage of the switch mode power supply is sensed. The switching device is controlled in response to the feedback signal and said comparing the current to the variable current limit threshold.

Abstract: A power source apparatus includes a first converter having a reactor L1, a switching element Q1, and a rectifier D1; a second converter connected in parallel with the first converter and having a reactor L2, a switching element Q2, and a rectifier D2; a capacitor C1 connected to output ends of the first and second converters; a current detector R1 detecting a resultant current of currents of the first and second converters; a controller 13 driving the switching element Q1 and the switching element Q2; and a selector. In a case where the resultant current indicates a first reference value, if one of first and second drive signals of the controller is active, the active drive signal is deactivated, and if both the first and second drive signals are active, one of the first and second drive signals that is active longer than the other is deactivated.

Abstract: The multi-level DC/AC converter, comprising: an input (5,7) connectable to a direct voltage source (3), with a first connection (5) and a second connection (7) between which can be applied an input voltage (Vi); a half-bridge with a first controlled switch (21) and a second controlled switch (25) between which is positioned an output (U) of the converter; a first connecting branch (15) between the first controlled switch (21) and the first connection (5) and a second connecting branch (17) between the second controlled switch (25) and the second connection (7); a third controlled switch (59) associated to the first controlled switch (21), connectable in series to the first controlled switch to generate an output voltage exceeding a first limit value (Vi/2); a fourth controlled switch (61) associated to the second controlled switch (25), connectable in series to said second controlled switch to generate an output voltage below a second limit value (?Vi/2).

Abstract: A pulse width modulation signal controlling apparatus including a signal pin, a core circuit, a setting judging circuit, a signal adjusting and selecting circuit, and a timer circuit is disclosed. The signal pin is connected to a setting device for receiving an external input signal. The setting judging circuit receives and compares a setting signal with a reference value to generate a setting judgment result. The signal adjusting and selecting circuit couples the signal pin to the setting judging circuit and adjusts the external input signal into the setting signal according to the setting device in a first state, and couples the signal pin to the core circuit in a second state. The timer circuit controls the state of the signal adjusting and selecting circuit, wherein the timer circuit sets the signal adjusting and selecting circuit in the first state during a predetermined time period.

Abstract: The invention deals with the control of a resonant LLC converter by setting up criteria for state parameters of the resonant converter, so that the converter may be operated in a near capacitive mode. The current flowing in the resonant tank and optionally the voltage at the a predetermined point in the resonant tank are monitored, and wherein a switch (a high side switch or a low side switch) is turned off when a first criterion is fulfilled together with a second criterion or optionally a third criterion, the first criterion ensuring a minimum time has lapsed after the switch is turned on, the second criterion being that the absolute value of the current is reaching a predetermined current level, the third criterion being that the voltage at the predetermined point reaches a predetermined voltage level.

Abstract: Disclosed are a maximum power point tracker, a power conversion controller, a power conversion device having an insulating structure, and a method for tracking maximum power point. The power conversion device includes: a DC/AC converter including a primary DC chopper unit having a primary switch, a transformer, and an AC/AC conversion unit including a secondary switch; a current detector detecting current from an input stage of the DC/AC converter and providing a detected current value; a voltage detector detecting a system voltage from an output stage of the DC/AC converter; and a power conversion controller generating a primary PWM signal to be provided to the primary DC chopper unit and secondary first and second PWM signals, having the mutually opposing phases, to be provided to the AC/AC conversion unit by using the detected current value and the system voltage.

Abstract: A switch-mode power supply (SMPS) is provided. When the switch power of the SMPS turns on, the inductor current of the SMPS may flow through an inductor current sensing circuit which then provides a sensing voltage. An apparatus for compensating the inductor current peak receives a reference voltage and the sensing voltage as inputs and outputs a compensation voltage. The compensation voltage is combined with the reference voltage and/or the sensing voltage and is provided to a first comparator. The result keep 7t as 7s is provided to the logic control circuit coupled to the gate of the power switch after being driven by a driver circuit. The actual inductor current peak is kept identical with the reference current, which effectively controls the inductor current peak, thereby protecting the SMPS.

Abstract: A switch bias system is provided that includes a bipolar junction transistor (BJT) switch comprising a base, emitter, and collector; a current sense circuit coupled to the emitter, the current sense circuit configured to sense current flow through the emitter of the BJT switch; and a proportional bias circuit configured to generate a bias current to the base of the BJT switch, the bias current set to a fixed proportion of the sensed current flow through the emitter of the BJT switch.

Abstract: A switching power controller circuit comprises a first terminal pin for a high potential of a power supply for the controller circuit, a second terminal pin for providing output of switch drive signals and for receiving feedback signals, and a third terminal pin for receiving external current signals and for a low potential of the power supply. The switching power controller further comprises a clock generator, a pulse width modulation (PWM) generator, a reference generator, a power switch driver, a feedback signal sampler, a PWM comparator and a floating sampler.

Abstract: Memory power estimation by means of calibrated weights and activity counters are generally presented. In this regard, in one embodiment, a memory power is introduced to read a value from a memory activity counter, to determine a memory power estimation based at least in part on the value and a calibration, and to store the memory power estimation to a register. Other embodiments are also described and claimed.

Abstract: A power supply having an input and an output, includes a power converter coupled between the input and output of the power supply including at least one switch that is controlled by comparing a sensed voltage, the sensed voltage corresponding to a current flowing through the switch, to a reference voltage. A controller, in response to a change detected in a switching frequency of the switch, reduces audible noise generated by the power supply by at least one of: adjusting the reference voltage; adjusting the current sense voltage; or adjusting a resistance used to generate the sensed voltage.

Abstract: A power converter including a detection apparatus and method for detecting an islanding condition based on measurements of one or more currents and voltages within the power converter provided to a current regulator to generate a signal that is provided in a positive feedback loop and is indicative of an islanding condition.

Abstract: System, power modules, and methods for supplying an output voltage to an electric grid are provided. One example power module includes a switching device configured to supply an output from a power generator to an electric grid, a feedback unit configured to provide a feedback signal indicative of a deviation of a parameter associated with the electric grid, and a controller coupled to the feedback unit and the switching device. The controller is configured to adjust a reactive current of the output in response to at least one grid fault event to ride through the at least one grid fault event, to modify the deviation provided from the feedback unit, to control the switching device based on the modified deviation, and to detect an islanding condition based on the parameter associated with the electric grid.

Abstract: An example controller for a power converter includes a switching control coupled to switch a power switch of the power converter to control a transfer of energy from an input of the power converter to an output of the power converter. A sensor is coupled to sample a single terminal of the controller during a portion of an off time of the power switch to output a signal representative of an output voltage of the power converter. The sensor is further coupled to sample the single terminal during a portion of an on time of the power switch to output a signal representative of a line input voltage of the power converter. The switching control is responsive to the sensor.

Abstract: A resonant inverter includes inductive elements (L1, L2) that allow the number of magnetic components in the inverter to be reduced. The elements (L1, L2) may be designed with a leakage inductance to eliminate the need for a large DC inductor. They may also perform the function of a current splitting transformer. The inverter switches may also be driven directly from the inverter circuit without a separate controller being required.

Abstract: We describe a modular adjustable power factor renewable energy inverter system. The system comprises a plurality of inverter modules having a switched capacitor across its ac power output, a power measurement system coupled to a communication interface, and a power factor controller to control switching of the capacitor. A system controller receives power data from each inverter module, sums the net level of ac power from each inverter, determines a number of said capacitors to switch based on the sum, and sends control data to an appropriate number of the inverter modules to switch the determined number of capacitors into/out of said parallel connection across their respective ac power outputs.

Abstract: An inverter device includes: an inverter circuit which includes an upper-arm-use first switching element (328U to 328W) and a lower-arm-use second switching element (330U to 330W); a control circuit (319) which outputs a first signal which is an ON/OFF command for the first switching element and a second signal which is an ON/OFF command for the second switching element respectively; a first drive circuit (610U to 610W) which performs ON/OFF driving of the first semiconductor switching element based on the ON/OFF command which is the first signal; a second drive circuit (611U to 611W) which performs ON/OFF driving of the second semiconductor switching element based on the ON/OFF command which is the second signal; and a signal switching part (616U to 616W) which directly inputs the first and second signals outputted from the control circuit to the corresponding first and second drive circuits respectively when at least one of the first and second signals is an OFF command, and interrupts inputting of the firs

Abstract: A sleep circuit for use in a resonant inverter is disclosed. The sleep circuit activates a “sleep mode” (non-continuous operation) when the inverter output has no connected load, or a connected load is non-operative (e.g., fails). The “sleep mode” utilizes hysteresis control via the under voltage lockout protection feature of a control IC of the inverter. A primary DC source permanently connects to the Vcc pin of the control IC for startup (on) and burst (non-continuous) operation modes. An auxiliary DC source connects to the Vcc pin via a switch for continuous operation mode. A load current sensor controls the switch. When a sensed output current is above a threshold level, the switch connects the auxiliary DC source, and the control IC (and the inverter) operates continuously. When the sensed output current falls below the threshold, the auxiliary DC source is not provided and the inverter operates in “sleep mode”.

Abstract: Novel system and methodology are provided for controlling a DC/DC forward converter having a transformer with primary and secondary windings, a reset switch, and a first switch coupled to the primary winding of the transformer. The control system involves a PWM control circuit responsive to an output signal of the converter for producing a PWM signal to control switching of the reset switch, and the first switch. A period of the PWM signal includes an on-time interval for enabling transfer of power via the transformer when the first switch is on, and a reset time interval for enabling reset of the transformer when the reset switch is on. A maximum value of the on-time interval is pre-set to provide sufficient time for the reset. The reset switch is turned off when the PWM signal goes from a first level to a second level. A first delay period is set between time when the reset switch turns off and time when the first switch turns on.

Abstract: A phase-controlled power supply is disclosed. The power supply includes a power conditioner with an input configured to connect to an external source of electrical power, the power conditioner being configured to provide conditioned power on its output. The power supply also includes a transformer having a primary winding and a secondary winding, and a switching module coupled between the output of the power conditioner and to the primary winding of the transformer. The switching module has two modes of operation and a control signal input configured to accept a first control signal. The switching module includes a switching element configured to connect the power conditioner output to the primary winding of the transformer. The switching module operates in the first mode when the first control signal is in a first state, switching the first switching element at a first frequency and first duty cycle.

Abstract: An isolated alternating current (AC)-direct current (DC) converter is disclosed. The isolated AC-DC converter comprises a slave control circuit including a slave driver module configured to receive a command and to control coupling of the slave control circuit to a primary-side inductor of a transformer based on the command, a master control circuit coupled to a secondary-side inductor of the transformer, the master control circuit including a master control module configured to sense a feedback voltage across a load and to generate the command based on the feedback voltage and a reference voltage, and a coupler configured to communicate the command from the master control module to the slave driver module and to provide isolation between the master control module and the slave driver module.

Abstract: A power converter with low power consumption during a standby operating condition. An example power controller includes a main converter coupled to a dc input of the power converter to control a transfer of energy from the dc input of the power converter to a main output of the power converter. A standby converter is also included and is coupled to the dc input of the power converter to control a transfer of energy from the dc input of the power converter to a standby output of the power converter during a standby operating condition of the power converter. A standby circuit is also included and is coupled to the dc input of the power converter and coupled to the main converter. The standby circuit decouples the main converter from the dc input of the power converter during the standby operating condition of the power converter.

Abstract: The present invention relates to an adapter power supply, which includes a switching unit for switching a DC voltage; a transformer which has a primary winding connected to the switching unit, a secondary winding electromagnetically coupled to the primary winding, and an auxiliary winding electromagnetically coupled to the primary winding; a rectifier for rectifying a voltage outputted from the transformer; and a controller for controlling the switching unit to operate according to the PWM scheme in a normal operation mode, and to operate according to a quasi-resonant scheme in a standby mode, by detecting information of a load connected to the rectifier.

Abstract: A switching power conversion circuit receives an input voltage and generates an output voltage to a system circuit. The switching power conversion circuit includes a power circuit, a feedback circuit, a control circuit, and an initiation circuit. The power circuit includes a first switch circuit. The feedback circuit generates a feedback signal according to a power-status signal and the output voltage. The first switching circuit is conducted or shut off according to the feedback signal under control of the control circuit, so that the input voltage is converted into the output voltage and the first auxiliary voltage by the power circuit. If the power-status signal is in an off status, a ratio of the feedback signal to the output voltage is equal to a first feedback ratio and the magnitude of the first auxiliary voltage is lower than a normal operating voltage value, so that the control circuit is disabled.

Abstract: A method of operating an inverter for converting direct voltage into alternating voltage. The inverter has direct-voltage terminals and alternating-voltage terminals and a plurality of power switching elements that are clocked at high-frequency connected between the d.c. and a.c. terminals. The high-frequency clocking of the power switching elements of the inverter is switched off around a zero transition of the alternating current or the alternating voltage for a period which depends on the direct voltage present at the direct-voltage terminals of the inverter and/or the output power of the inverter. No current is generated during time intervals with a poor efficiency.

Abstract: A first rectifier diode is electrically connected between a first input terminal where an alternating current (AC) power is received and a first output terminal where a direct current (DC) power is output. A second rectifier diode is electrically connected between the first input terminal and a second output terminal. The first and second rectifier diodes rectify first and second portions of the AC power into the DC power, respectively. When switching of a plurality of power factor correction (PFC) switches is enabled, the plurality of PFC switches increases a voltage of the DC power to greater than a peak voltage of the AC power. An inductor is electrically connected between a second input terminal and two of the plurality of PFC switches. When the switching is disabled, first and second bypass diodes provide a current path past the plurality of PFC switches and the inductor.

Abstract: In one embodiment, each of a plurality of sites may produce surplus power. All or a fraction of the surplus power may be supplied to the power grid according to an agreement between the user of a site and an electric utility. A computer of the utility is in communication with a computer at each of a plurality of sites having a local power source. Terms of power provision that include an amount of power to be provided during a specified time of day is communicated between a site and the utility.

Abstract: A plurality of power supply circuits Z1? are provided according to a load capacity. The power supply circuits Z1? have sides connected in parallel on the side of a direct current input Vi and have sides connected in series on the sides of alternating current outputs Ao. A rectifying circuit DC1 is connected via a resonance circuit Z2 across a combined output of the serially connected sides of the power supply circuits Z1? on the sides of the alternating current outputs Ao. Switching frequencies are simultaneously controlled by a single control signal outputted from a control circuit S1 based on a direct current output voltage detected from the rectifying circuit DC1 through a detection resistor R5.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: A ground power unit having a power supply unit capable of accepting a wide range of AC input voltages and producing one or more DC power signals for powering components of the GPU is disclosed. In one embodiment, the power supply unit includes a rectifier that converts an AC input power to a DC link power. The power supply unit includes a gate driving circuit that has a power MOSFET transistor which, under the control of a PWM controller, produces a switched DC signal. The DC link power and the output of the gate drive circuitry are provided to a transformer, which modulates the signals and produces a first DC output power signal that is load independent and a second DC output power signal that is load dependent.

Abstract: An output voltage sensor for use in a power converter controller includes a first pulse sampler circuit coupled to receive a feedback signal representative of an output of a power converter. The first pulse sampler circuit is coupled to capture a first peak voltage representative of a second peak of a ringing voltage of the feedback signal at a first time in the feedback signal. A second pulse sampler circuit is coupled to receive the feedback signal representative of the output of the power converter. The second pulse sampler circuit is coupled to capture a second peak voltage representative of the second peak of the ringing voltage of the feedback signal at a second time in the feedback signal. The output voltage sensor is coupled to output a change signal to a drive circuit of the power converter controller in response to the first and second peak voltages.

Abstract: Ripple of an input voltage is used to modulate a switching operation frequency of a switch mode power supply. A sensing voltage corresponding to the input voltage is received, a current ripple that is proportional to a difference between a peak value of the sensing voltage and the sensing voltage is generated, and a modulation control signal that is variable by the current ripple is generated. A switching frequency is modulated using an oscillator signal that is variable by the modulation control signal, and reduces the output voltage ripple.

Abstract: A semiconductor device providing a control circuit for controlling a switching power supply apparatus includes: an intermittent-oscillation control circuit which outputs an enable signal providing instructions to execute and suspend switching alternately; a turn-on control circuit which changes between an execution state and a suspension state of the switching according to the enable signal, and outputs, only in the execution state, a turn-on signal which turns on the switching element with a switching period; and an intermittent-oscillation frequency control circuit which causes the turn-on control circuit to delay the changing between the execution state and the suspension state so that an intermittence period including periods during which the turn-on control circuit is in the execution state and the turn-on control circuit is in the suspension state falls outside of a specific time range. Intermittent oscillation is thus operated out of a specific frequency band within an audible frequency range.

Abstract: System and method for regulating an output voltage of a power conversion system. The system includes an error amplifier coupled to a capacitor. The error amplifier is configured to receive a reference voltage, a first voltage, and an adjustment current and to generate a compensation voltage with the capacitor. The first voltage is associated with a feedback voltage. Additionally, the system includes a current generator configured to receive the compensation voltage and generate the adjustment current and a first current, and a signal generator configured to receive the first current and a second current. The signal generator is further configured to receive a sensing voltage and to generate a modulation signal. Moreover, the system includes the gate driver directly or indirectly coupled to the signal generator and configured to generate a drive signal based on at least information associated with the modulation signal.

Abstract: An example power supply includes an energy transfer element, a switch and a controller. The controller includes a logic circuit and a constant current control circuit. The logic circuit generates a drive signal to control the switch in response to a control signal. The constant current control circuit generates the control signal in response to a received input current sense signal, input voltage sense signal, and output voltage sense signal. An integrator included in the constant current control circuit integrates the input current sense signal to generate an integrated signal representative of a charge taken from the input voltage source. The constant current control circuit is adapted to generate the control signal to provide a constant current at the output of the power supply such that the integrated signal is proportional to a ratio of the output voltage sense signal to the input voltage sense signal.

Abstract: An adaptive inductive ballast is provided with the capability to communicate with a remote device powered by the ballast. To improve the operation of the ballast, the ballast changes its operating characteristics based upon information received from the remote device. Further, the ballast may provide a path for the remote device to communicate with device other than the adaptive inductive ballast.

Abstract: A control section controls a current-source converter simultaneously with or prior to conduction of a power supply switch to connect a clamp capacitor and capacitors between a first input line on which a resistor is provided and any one of second and third input lines in parallel with each other. Accordingly, current is transmitted to the clamp capacitor via the resistor when the power supply switch is brought into conduction, which prevents inrush current from flowing to the clamp capacitor. In addition, for example, the capacitors are not charged prior to the clamp capacitor, whereby it is possible to prevent the inrush current from flowing from the capacitors to the clamp capacitor when they are connected in parallel with each other.

Abstract: An example controller includes a delayed ramp generator, an integrator, an arithmetic operator, and a drive signal generator. The integrator integrates an input current sense signal representative of an input current of the power supply to generate an input charge signal. The input current has a pulsating waveform with a period that is a switching period of a switch of the power supply. The arithmetic operator circuit generates an input charge control signal responsive to the input charge signal and a ratio of a rectified input voltage to a dc output voltage of the power supply. The drive signal generator produces a drive signal responsive to the input charge control signal and a delayed ramp signal generated by the drive signal generator to control the switch.

Abstract: A resonant power conversion apparatus includes a transformer T1 having a primary winding n1, a secondary winding n2, a tertiary winding n3, and a reset winding nR, a series circuit of switches S1 and S2, a capacitor Cr1 and diode D1 to the switch S1, a capacitor Cr2 and diode D2 to the switch S2, a series circuit of the winding n1 and a diode Dn1, a series circuit of the winding nR and a diode DR, a reactor Lr connected between a connection point of the switches S1 and S2 and a connection point of the windings n2 and n3, a switch S10 connected between the DC power source and the winding n2, a switch S20 connected between the DC power source and the winding n3, and a controller 10 configured to perform a zero-voltage switching operation of the switches S1 and S2.

Abstract: A switching mode power supply includes a switching transistor, coupled to a primary coil at a primary side of a transformer for converting an input DC voltage, supplying power to a secondary and a tertiary coil at a secondary side of the transformer according to an operation of the switching transistor; a switching controller receiving a feedback voltage corresponding to a first voltage generated in the secondary coil and receiving a detection signal corresponding to a current of the switching transistor to generate a switching control signal for controlling the turn on/off of the switching transistor; and a feedback signal generator receiving the first voltage and the switching control signal to set a sampling period, and storing the first voltage, sampled with a last pulse of the first pulse string within the sampling period as a feedback voltage. The output voltage is thereby accurately detected without opto-couplers or shunt regulators.