Abstract: A flyback converter includes a primary side circuit to receive an input voltage signal, a secondary side circuit to generate an output voltage signal using the input voltage signal, a synchronous rectifier switch, and a synchronous rectifier controller. The synchronous rectifier controller receives an attenuated drain-source voltage signal of the synchronous rectifier switch and the output voltage signal. The synchronous rectifier controller includes a threshold voltage generator to generate a first voltage signal using the output voltage signal, a first comparator to compare the attenuated drain-source voltage signal to the first voltage signal and, in response, generate a first comparison signal, and a second comparator to compare the attenuated drain-source voltage signal to a second voltage signal and, in response, generate a second comparison signal.

Abstract: A switching power supply apparatus includes a PFM control circuit that outputs a clock signal Set such that a switching frequency of a switching element varies in accordance with a load state. The clock signal Set determines a turn-on timing of the switching element. A reference value of a current flowing through the switching element determines a turn-off timing of the switching element. A modulation signal is applied to the turn-off timing of the switching element to modulate one of a peak value of a drain current flowing through the switching element and an on-time of the switching element. Input control is performed separately on the clock signal Set and the modulation signal. Accordingly, even when the clock signal Set and the modulation signal contribute to each other to offset each other, modulation effects are not cancelled.

Abstract: A switching power supply circuit includes an intermittent oscillation control circuit, which performs intermittent oscillation control that repeats a cycle including an oscillation time period and a stop time period according to a feedback signal so that output voltage or current becomes constant, compares an intermittent oscillation period that is a sum of the oscillation time period and the stop time period with a preset target period, sets the oscillation time period of current cycle to a length obtained by extending the oscillation time period of previous cycle by first predetermined time when the intermittent oscillation period is shorter than the target period, and sets the oscillation time period of current cycle to a length obtained by subtracting second predetermined time from the oscillation time period of previous cycle when the intermittent oscillation period is longer than the target period, in each cycle of intermittent oscillation control.

Abstract: A method for controlling a DC-to-DC converter includes detecting an output current and an output voltage of the DC-to-DC converter, controlling the DC-to-DC converter to switch from a voltage loop control mode to a current loop control mode based on a comparison result of the output current with a first current threshold and a comparison result of the output voltage with a first voltage threshold, and reducing a duty ratio of a switch in the DC-to-DC converter by a first predetermined amount based on the output current. A section to which the output current belongs is determined from a plurality of candidate current sections, and a predetermined amount corresponding to the section to which the output current belongs is determined as the first predetermined amount by which the duty ratio of the switch is reduced. Reliability of the DC-to-DC converter may be improved.

Abstract: A direct charging method is provided that alerts a mobile device when a switching power converter is operating in a constant-current mode to alert the mobile device of an output current without the use of a secondary-side current sense resistor.

Abstract: The present invention provides a power switch control circuit and an open detection method thereof. The power switch control circuit is for generating an operation signal at an operation signal output pin according to an input signal, wherein the operation signal is for operating a power switch. The power switch control circuit includes: a current injection circuit, which is connected to the operation signal output pin, and provides a predetermined current to the operation signal output pin according to an enable signal; and an open detection circuit, which is coupled to the current injection circuit, and determines whether a connection between the operation signal output pin and the power switch is open according to a level of the operation signal output pin at a detection time point or according to a level variation of the operation signal output pin during a detection time period, whereby an open detection signal is generated.

Abstract: An improved power converter produces power through a power switch in response to an activation signal that has an on-time and a switching frequency. An on-time signal has a constant on-time and controls the on-time of the activation signal. An error signal indicates that the switching frequency is not equal to a reference frequency. A step up signal and a step down signal are based on the error signal. A count signal is increased in response to the step up signal and decreased in response to the step down signal. An on-time pulse has a duration that is related to a value of the count signal. The on-time pulse controls the constant on-time of the on-time signal and maintains the switching frequency at about the reference frequency.

Abstract: An LED luminaire comprises a rechargeable battery, LED array(s), at least two drivers, a battery charging circuit, and a detection and control circuit. The LED luminaire may be used to replace a fluorescent or a conventional LED lamp connected to AC mains. The at least two drivers comprise a power switching driver and a constant current driver. The power switching driver is configured to power the LED array(s) and the battery charging circuit whereas the constant current driver is configured to convert a battery terminal voltage from the rechargeable battery to a DC voltage to light up the LED array(s) when a line voltage from the AC mains is unavailable. The detection and control circuit is configured to disable the constant current driver when the line voltage from the AC mains is available or to enable the constant current driver when the line voltage from the AC mains is unavailable.

Abstract: Disclosed are DC-to-AC converter control methods, ground assemblies and wireless power transfer methods using the same. A method for controlling a DC-to-AC converter of a ground assembly used for wireless power transfer, which includes first, second, third, and fourth switches arranged in a form of a bridge circuit between a power source and a primary coil, may comprise detecting a current flowing through the primary coil at a rising edge of an output voltage signal of the DC-to-AC converter; determining whether a strength of the current is at a negative level which falls within a predetermined reference range; and in response to a determination that the current is not at the negative level, changing switching frequencies of the DC-to-AC converter.

Abstract: A regenerative current detection circuit includes a first power MOS transistor that is configured as a current mirror to a second power MOS transistor connected to drive a motor winding, a first feedback amplifier that compares a first regenerative current that flows in the first power MOS transistor with a second regenerative current that flows in the second power MOS transistor and outputs a comparison result, the first regenerative current being obtained by multiplying the second regenerative current by a current mirror ratio, and a current detection circuit that outputs a detection current based on the comparison result.

Abstract: An integrated circuit may detect a pin voltage at a selector pin. The integrated circuit may compare the pin voltage to a threshold voltage. The integrated circuit may selectively perform primary side voltage regulation or secondary side voltage regulation, to regulate a voltage supplied to an electrical load coupled to the integrated circuit, based on comparing the pin voltage and the threshold voltage.

Abstract: A light-emitting diode (LED) smart control circuit and the related LED lighting device are provided. The LED smart control circuit includes a microprocessor, a bridge rectifier, a transformer circuit, a power grid detection unit, a voltage detection unit, a battery charging controller, a first sampling circuit, a second sampling circuit, a constant current controller, and an external rechargeable battery. The LED smart control circuit is configured for controlling LED light source components to emit light. An LED lighting device includes the LED light source components, a smart control circuit board, a rechargeable battery, a shell, and a lamp head. The smart control circuit board is integrated with the disclosed LED smart control circuit.

Abstract: A controller includes a first power circuit, a second power circuit, and a charging control circuit. The first power circuit is coupled to a bypass terminal and a first terminal to be coupled to receive charge from a secondary winding. The first power circuit transfers charge from the first terminal to the bypass terminal. The second power circuit is coupled to the bypass terminal and a second terminal to be coupled to a receive charge from an output of a power converter. The second power circuit transfers charge from the second terminal to the bypass terminal. The charging control circuit controls which of the first and second power circuits transfers charge to the bypass terminal.

Abstract: Magnetically isolated feedback circuits and regulated power supplies are disclosed. In some embodiments, a magnetically isolated feedback circuit includes an isolated gate drive circuit and a forward converter circuit. The isolated gate drive circuit is operable to receive a plurality of pulses, wherein the isolated gate drive circuit produces a plurality of isolated bi-polar pulses from the plurality of pulses. The forward converter circuit is electrically coupled to the isolated gate drive circuit and is operable to be electrically coupled to a load. The plurality of isolated bi-polar pulses causes the forward converter circuit to sample a voltage at the load as a sampled voltage. The forward converter circuit is operable to provide the sampled voltage to a feedback input of a pulse width modulator.

Abstract: In one embodiment, a controller for a power supply may be configured to operate as a quasi-resonant controller while operating in a discontinuous current mode and to operate as one of a pulse width or pulse frequency modulation controller while operating in a continuous current mode. The controller may have an embodiment that varies a frequency of the switching drive signal around a center frequency while operating in the continuous current mode, and varies a value of a current sense signal but not vary the frequency of the switching drive signal around a center frequency while operating in the discontinuous current mode.

Abstract: A power and data communication system includes an inboard computer, an outboard computer, and first and second wires. The first and second wires connect a first isolation transformer of the inboard computer to a second isolation transformer of the outboard computer. The inboard computer drives a driven voltage through the first isolation transformer. The outboard computer is configured to receive the driven voltage through the second isolation transformer to power the outboard computer. The outboard computer incudes a load that is selectively connected across the second isolation transformer to transmit data to the inboard computer. The inboard computer receives the data through the first isolation transformer.

Abstract: A constant voltage and current synchronic output power supply and a television are disclosed. The constant voltage and current synchronic output power supply comprises a transformer for supplying power to LED loads, a conversion circuit for converting an inputted AC power supply to a DC square wave power supply that is provided to the transformer, a PWM control circuit for driving the transformer, a constant voltage control circuit and a constant current control circuit, the transformer comprises a constant voltage output winding and a constant current output winding, wherein the constant voltage control circuit is configured for sampling voltages outputted by the constant voltage output winding then transferring the sampled voltages into the corresponding signals that are feedbacked to the PWM control circuit, to perform constant voltage control on the output voltage of the transformer.

Abstract: System and method for regulating a power conversion system. A system controller for regulating a power conversion system includes a first controller terminal and a second controller terminal. The system controller is configured to receive at least an input signal at the first controller terminal, and generate a gate drive signal at the second controller terminal based on at least information associated with the input signal to turn on or off a transistor in order to affect a current associated with a secondary winding of the power conversion system. The system controller is further configured to, if the input signal is larger than a first threshold, generate the gate drive signal at a first logic level to turn off the transistor.

Abstract: An isolated switching mode power supply and a control method of the isolated switching mode power supply are provided. The isolated switching mode power supply includes a primary side circuit and a secondary side circuit. The primary side circuit includes a controller. The secondary side circuit is coupled to the primary side circuit and includes a winding, a switch, and an SR controller. The winding is coupled to the primary side circuit. The switch is coupled to the winding. The SR controller is coupled to the winding and the switch. The SR controller turns off the switch to trigger the winding to feed back a first message to the primary side circuit. The controller enables the primary side circuit to transfer energy to the secondary side circuit if the controller detects the first message.

Abstract: A control device includes a searching unit increasing or decreasing, at a predetermined step width, an operation voltage or an operation current of a power supply connected to a power converter to search a maximum power point of the power supply, a consecution time determining unit determining whether or not the searching unit has consecutively increased or decreased the operation voltage of the power supply or the operation current thereof, and a step width increasing unit increasing the step width upon determination by the consecution time determining unit that the increase or the decrease has been consecutively executed by a predetermined number of times.

Abstract: System and method for regulating a power conversion system. A system controller for regulating a power conversion system includes a first controller terminal and a second controller terminal. The system controller is configured to receive at least an input signal at the first controller terminal, and generate a gate drive signal at the second controller terminal based on at least information associated with the input signal to turn on or off a transistor in order to affect a current associated with a secondary winding of the power conversion system. The system controller is further configured to, if the input signal is larger than a first threshold, generate the gate drive signal at a first logic level to turn off the transistor.

Abstract: A converter and a driving method thereof are disclosed. The converter includes a transformer, a main switch, a clamp switch, and a switching controller. Here, the switching controller controls a turn-on time of the main switch and a turn-off time of the clamp switch corresponding to an output load.

Abstract: Several defibrillators, defibrillator architectures, defibrillator components and methods of operating defibrillators are described. In one aspect, a defibrillator (as for example an automated external defibrillator) that can be powered by a mobile communication device such as a smart cellular phone or a tablet computer is described. Utilizing a phone (or other mobile communication device) as the power supply for an external defibrillator allows the external defibrillator to be smaller and, in some circumstance, removes the need for a battery that stores sufficient energy for shock delivery—which would need to be checked and/or replaced on a regular basis. Additionally, when desired, certain control functionality, computation, data processing, and user instructions can be handled/presented by the mobile communications device thereby further simplifying the defibrillator design and improving the user experience.

Abstract: A method for modulating a voltage through a primary side regulating circuit and a secondary side regulating circuit, the method includes: providing a first controller in the primary side regulating circuit; providing a second controller in the secondary side regulating circuit; exchanging messages between the first controller and the second controller thereby alternately dominating a modulation of an output voltage between the primary side regulating circuit and the secondary side regulating circuit in accordance with the messages.

Abstract: In some examples, a method includes measuring, by a secondary controller, an output voltage and determining, by the secondary controller, a duration for a ringing time based on the output voltage. In some examples, the method further includes delivering, by the secondary controller, a non-enabling control signal to a secondary switch during the ringing time and measuring, by a primary controller, a duration of the ringing time. In some examples, the method also includes determining, by the primary controller, a duration for a charging time based on the duration of the ringing time and delivering, by the primary controller, an enabling control signal to a primary switch during the charging time.

Abstract: In one embodiment, a voltage peak detection circuit can include: (i) a voltage coupling circuit configured to inductively couple an input inductor voltage of a switching power supply, and to generate a first voltage that represents a DC input voltage of the switching power supply; (ii) a voltage conversion circuit configured to receive the first voltage, and to generate a second voltage that is proportional to the first voltage; and (iii) a holding circuit configured to hold a peak of the second voltage to generate a peak voltage signal that represents peak information of the DC input voltage.

Abstract: The feedback IC is provided at the secondary side of the DC/DC converter and is coupled to the photo coupler. The error amplifier amplifies an error between a voltage detection signal according to an output voltage of the DC/DC converter and a target voltage, and draws a current according to the error from the input side of the feedback photo coupler via the photo coupler connection terminal. The abnormal detection circuit asserts an abnormal detection signal when an abnormal condition in a secondary side of the DC/DC converter is detected. The protection circuit is coupled to the photo coupler connection terminal, and acts on the feedback photo coupler via the photo coupler connection terminal so that a feedback operation by the error amplifier is invalid and an on-period of the switching transistor is shorten.

Abstract: A control circuit for driving a power switch in a switching power supply can include: a start-up transistor having a drain coupled to a drain of the power switch, and a source coupled to a drain voltage detecting circuit; a gate voltage detecting circuit configured to detect a gate voltage of the power switch, to compare the gate voltage against a first threshold voltage, and to change an on drive current and an off drive current in response thereto; and the drain voltage detecting circuit being configured to detect a drain voltage of the power switch, to compare the drain voltage against a second threshold voltage, and to change the on drive current and the off drive current in response thereto.

Abstract: An AC-to-DC power converter with a BJT as a power switch can set a base current of the BJT by a current setting resistor which is in the outside of a control integrated circuit. Since an output current and a recovery current of the BJT are injected into a sensing resistor, the AC-to-DC power converter can correctly detect an inductor current thereof from the sensing resistor.

Abstract: A power conversion device and a method for correcting decision threshold level thereof are disclosure. The method for correcting awaking-voltage of a power conversion device is provided. The method includes: fixing an output current of the power conversion module; monitoring a real decision threshold level of the power conversion module when the power conversion module departs from a burst mode; adjusting a preset decision threshold level based on the comparison between the real decision threshold level and the preset decision threshold level to make the preset voltage be equal to the real decision threshold level.

Abstract: A power converter controller includes a drive circuit that generates a drive signal to switch a power switch to control a transfer of energy to an output of the power converter in response to a current sense signal, a feedback signal, and a current limit signal. A current limit generator generates the current limit signal in response to a load coupled to the output. An audible noise detection circuit generates a frequency skip signal in response to the drive signal to indicate when an intended frequency of the drive signal is within an audible noise frequency window. A state of the current limit signal fixed when the intended frequency of the drive signal is within the audible noise frequency window. A first latch generates a hold signal to control the current limit generator to hold the current limit signal in response to the frequency skip signal and the feedback signal.

Abstract: A controller for use in a power converter includes a drive circuit coupled to generate a drive signal to control switching of a power switch of the power converter in response to a feedback signal to control a transfer of energy from an input to an output of the power converter. An audible noise window circuit is coupled to generate a frequency skip signal in response to the feedback signal. The frequency skip signal is activated in response to a frequency of a feedback request signal responsive to the feedback signal being within an audible noise window. An audible noise reduction circuit is coupled to output a reduction signal in response to the frequency skip signal. The drive circuit is coupled to generate the drive signal in response to the reduction signal from the audible noise reduction circuit.

Abstract: Systems and methods are provided for power conversion system regulation. A system controller includes: a first signal processing component configured to receive a first signal associated with an auxiliary winding of a power conversion system and generate a second signal based at least in part on the first signal, the power conversion system further including a primary winding and a secondary winding; and a drive component configured to receive the second signal and output a drive signal to open or close a switch to affect a current flowing through the primary winding. The first signal processing component is further configured to: detect a plurality of valleys of the first signal, the plurality of valleys corresponding to a same demagnetization process of the power conversion system; select a valley from the plurality of valleys; and change the second signal at the selected valley.

Abstract: A converter control system includes an analog-to-digital converter, a filter and a control module. The analog-to-digital converter digitalizes a different-time and a real-time feedback voltage. The filter bases on the different-time feedback voltage to sample a historical average feedback voltage. The control module receives the real-time feedback voltage, bases on the historical average feedback voltage to detect a load status of the converter, and bases on the real-time feedback voltage and the historical average feedback voltage to derive a voltage difference. The control module applies a control duty cycle to control the load switch. While the control module detects that the load status switches to a heavy-load status and the voltage difference reaches the threshold voltage, the control duty cycle is increased. While the control module detects that the load status switches to the light-load status and the voltage difference reaches the threshold voltage, the control duty cycle is decreased.

Abstract: A mode selection circuit generates a mode voltage according to a clamping current flowing when a voltage of a multi-pin is clamped to a predetermined clamping voltage, and selects one of a plurality of mode signals according to the mode voltage. The mode voltage is controlled according to a passive element connected to the multi-pin.

Abstract: A power circuit is described that includes a transformer arranged to store energy. The power circuit further includes a parallel switch device arranged in parallel to a secondary side winding of the transformer, an output port coupled to a device and the secondary side winding of the transformer, and a control unit. The control unit is configured to receive, from the device, information indicative of a required voltage associated with the device, and control, based on the information, the parallel switch device to generate, based on an amount of energy stored at the transformer, the required voltage as an output voltage at the output port.

Abstract: A bidirectional voltage differentiator circuit comprises start-up circuitry, sensing circuitry, and output circuitry coupled to logic circuitry. The start-up circuitry acts to start-up the sensing circuitry when the circuit is powered on, and accelerates the response of the sensing circuitry thereafter. The sensing circuitry senses variation in an input voltage applied to an input node. Responsive to the voltage variation sensed by the sensing circuitry, the output circuitry produces a state change at a first or second output node. The logic circuitry receives the states of the output nodes and produces a logic output signal to indicate the occurrence of the variation sensed in the input voltage. The voltage sensing circuit is operable to sense variation of the input voltage regardless of whether the voltage is rising or falling and without regard to the DC value of the input voltage.

Abstract: The present invention pertains to an inductor current detection circuit in a switching mode power supply, and a light-emitting diode (LED) driver thereof. In one embodiment, an inductor current detection circuit configured in a switching mode power supply under discontinuous conduction mode, can include: (i) a voltage detection circuit configured to generate a sampling voltage based on a drain-source voltage of a power switch in the switching mode power supply; (ii) a voltage holding circuit configured to receive the sampling voltage, and to generate a holding voltage through a sampling and holding operation; and (iii) a comparison circuit configured to compare the sampling voltage against the holding voltage, and to generate a zero-crossing signal when the sampling voltage is less than the holding voltage, where the zero-crossing signal is configured to represent an inductor current ending time of the switching mode power supply.

Abstract: An image forming apparatus includes: a plurality of image forming units forming an image in the corresponding color by electrophotographic system; a high-voltage power supply circuit capable of generating a bias voltage; and a control unit that controls a first printing mode and a second printing mode, wherein in the second printing mode, the control unit performs such control that the photosensitive bodies provided on the image forming units not used in the second printing mode continuously rotate at a speed lower than a speed in the first printing mode, and/or such control that a bias voltage whose absolute value is less than an absolute value of a bias voltage in the first printing mode is supplied from the high-voltage power supply circuit to the processing components of the same type provided on the image forming units not used in the second printing mode.

Abstract: A power source delivers power from a main power source using switching by a normally on transistor. A driver switches on and off the normally on transistor under a control signal by a controller during regular operation. A housekeeping power supply delivers auxiliary power to the driver. The driver switches off the normally on transistor during irregular operation. Irregular operation occurs at least when the control signal is absent or no auxiliary power is available or during transients such a power up or down. Bridge block pairs thereof can be arranged to form a half bridge power switch, an H bridge switch, a three phase bridge switch, a multi-phase switch, a buck converter, a buck-boost converter, or a boost converter.

Abstract: The present invention provides a flyback power converter with a programmable output and a control circuit and a control method thereof. The flyback power converter converts an input voltage to a programmable output voltage according to a setting signal, wherein the programmable output voltage switches between different levels. The flyback power converter includes: a transformer circuit, a power switch circuit, a current sense circuit, an opto-coupler circuit, and a control circuit. The control circuit adaptively adjusts an operation signal according to a level of the programmable output voltage, to maintain a same or relatively higher operation frequency of the operation signal when the programmable output voltage switches to a relatively lower level, so as to maintain a phase margin while supplying the same output current.

Abstract: LED systems and circuits for generating a driver output for powering one or more LED devices are provided. A dimmable driver circuit can include a controller configured to reduce output ripple current to reduce flicker over the dimming range of the LED system. The dimmable driver circuit can receive a dimming control signal (e.g. a 0V to 10V dimming control signal) over an isolated dimming interface to reduce leakage current at the dimming interface. In addition, a dual-switch flyback converter circuit can be employed to increase efficiency of the driver circuit as well as to reduce electromagnetic interference (EMI) with the LED devices, such as EMI resulting from differential mode noise.

Abstract: System and method for regulating an output voltage of a power conversion system. The system includes a sampling component located on a chip, which for example, receives an input voltage through a terminal. The sampling component, for example, samples the input voltage and generates a sampled voltage. Additionally, the system includes an error amplifier which for example, processes information associated with the sampled voltage and a threshold voltage and generates a first output signal, and a first signal generator which for example, generates a second output signal and one or more third output signals. Moreover, the system includes a comparator which for example, receives the first output signal and the second output signal and generates a comparison signal, and a gate driver directly or indirectly coupled to the comparator. The gate driver, for example, generates a drive signal based on at least information associated with the comparison signal.

Abstract: A circuit for electromagnetic interference (EMI) reduction contains a signal input, a signal output, a pulse count controlling unit, a stand-by power reduction unit, a pulse series delay unit, and a temperature sensing unit. An alternating current (AC) input is provided to the signal input and the modified signal is drawn out from the signal output. The pulse count controlling unit and the pulse series delay unit modify the pulses of the pulse-width modulation process such that the overall efficiency of the circuit is increased. In particular, the pulse count controlling unit increases the number of pulses per cycle such that additional power is transferred onto the output load. On the other hand, the pulse series delay unit shifts the start time of a series of pulses such that the overall emission is reduced. The stand-by power reduction unit disconnects power when a circuit overload occurs.

Abstract: The drive current of the switch in a switching power converter is adjusted dynamically according to line or load conditions within a switching cycle and/or over a plurality of switching cycles. The magnitude of the switch drive current can be dynamically adjusted within a switching cycle and/or over a plurality of switching cycles, in addition to the pulse widths or pulse frequencies of the switch drive current.

Abstract: In one embodiment, a voltage peak detection circuit can include: (i) a voltage coupling circuit configured to inductively couple an input inductor voltage of a switching power supply, and to generate a first voltage that represents a DC input voltage of the switching power supply; (ii) a voltage conversion circuit configured to receive the first voltage, and to generate a second voltage that is proportional to the first voltage; and (iii) a holding circuit configured to hold a peak of the second voltage to generate a peak voltage signal that represents peak information of the DC input voltage.

Abstract: The present invention discloses a LED driver including a power stage, an inductor, an error amplifier, a set comparator, a first timer, a logical AND circuit, a reset comparator, a second timer a logical OR circuit, a RS flip flop and a driving circuit. The LED driver provides sufficient latching current for the TRIAC dimmer with no large RC circuit, so as to optimize the dimming and reduce system size.

Abstract: Flyback converters are disclosed herein. An embodiment of a flyback converter includes a transformer having a primary side and a secondary side. A switch is connected to the primary side of the transformer, wherein the switch controls the current in the primary side of the transformer. A resistance is connected between the switch and a common node. The converter also includes a comparator having a first input and a second, the first input being connected between the switch and the resistor. Driver logic controls the state of the switch, wherein the output of the comparator is coupled to the driver logic. A voltage source is connected to the second input of the comparator. An error amplifier compares the voltage at the second input of the comparator to an adjustment voltage, the output of the error amplifier is coupled to the driver logic.

Abstract: An output power adjusting method is applied on an inverter. The inverter includes a capacitor to store direct current (DC) electricity provided by a photovoltaic (PV) module. At least the DC electricity provided by the PV module is converted into alternating current (AC) electricity. Determine whether a power value of the AC electricity exceeds a power threshold. When the AC electricity exceeds the power threshold, the inverter works in a continuous mode. When the AC electricity does not exceed the power threshold, the inverter works in a discontinuous mode where the PV module charges the capacitor. In the discontinuous mode, determine whether a voltage on the capacitor exceeds a reference voltage, and when the voltage on the capacitor exceeds the reference voltage, the DC electricity provided by the PV module and DC electricity in pulses provided by the capacitor are converted to the AC electricity.

Abstract: A switching power supply system includes a transformer having a primary winding, a secondary winding and a tertiary winding, a switching device inputted to the primary winding carrying out switching operation on the basis of a first control signal or a second control signal, an output voltage producing section rectifying and smoothing a voltage generated in the secondary winding to produce an output voltage, an output voltage detecting section producing an output voltage detection signal based on a voltage generated in the tertiary winding, a checking pulse generator generating pulses of the first control signal, and a switching controlling section producing the second control signal on the basis of the output voltage detection signal. The switching power supply system is capable of carrying out stable control of the output voltage on the secondary winding side of the transformer with a low power loss.