Abstract: A circuit arrangement for limiting excessive voltages by a forward delay time of a first diode is described. The first diode is alternately switched in a non-conducting direction and a conducting direction by switching a circuit element. The first diode is series-connected to a first capacitor and a pre-charging circuit is provided for the first capacitor, the pre-charging circuit charging the first capacitor while the first diode is switched in the non-conducting direction. The pre-charging circuit charges the first capacitor more strongly than an excessive voltage of the first diode with regard to the amount.

Abstract: A semiconductor device of the present invention includes a switching transistor, and a recovery diode and a snubber device which are mounted on a single conductive substrate (frame) on which the switching transistor is also mounted. The snubber device includes a SiC-MOSFET connected between an output terminal C and a reference terminal E of the switching transistor, a Zener diode formed between a gate terminal G and a drain terminal D of the SiC-MOSFET, and a resistor formed between the gate terminal G and a source terminal S of the SiC-MOSFET. The reference terminal E of the switching transistor, the source terminal S of the SiC-MOSFET, and an anode terminal of the recovery diode are commonly connected.

Abstract: In one embodiment, a power converter system comprises an input terminal operable to connect to a DC power source and an output terminal at which an output voltage can be provided. An active clamped forward converter is operable to provide forward power flow from the DC power source to the output terminal. A flyback converter is operable to provide backward power flow from the output terminal to the DC power source. The active clamped forward converter and the flyback converter cooperate to generate a rectified sinusoidal waveform at the output terminal.

Abstract: The present invention discloses a forward-flyback converter with active-clamp circuit. The secondary side of the proposed converter is of center-tapped configuration to integrate a forward circuit and a flyback circuit. The flyback sub-circuit operating continuous conduction mode is employed to directly transfer the reset energy of the transformer to the output load. The forward sub-circuit operating discontinuous conduction mode can correspondingly adjust the duty ratio with the output load change. Under the heavy load condition, the mechanism of active-clamp flyback sub-circuit can provide sufficient resonant current to facilitate the parasitic capacitance of the switches to be discharged to zero. Under the light load condition, the time interval in which the resonant current turns from negative into positive is prolonged to ensure zero voltage switching function. Meanwhile, the flyback sub-circuit wherein the rectifier diode is reverse biased is inactive in order to further reduce the power losses.

Abstract: A clamping circuit is included in a phased motor control circuit, particularly on an electrical connection connected to at least one electrostatic discharge cell and/or the driver control electronics of the phased motor control circuit. The clamping circuit triggers when a voltage that exceeds a clamping turn-on threshold occurs on the electrical connector, sourcing or sinking the discharge current so as to protect the electrostatic discharge cells and/or driver control electronics from destruction by said discharge current.

Abstract: Self-powered supplies with on-board diagnostics are presented for powering a power converter switch driver with power obtained from an associated snubber circuit, including a first converter stage with a full bridge rectifier with a crowbar circuit creating a first DC bus and a second stage with an isolated DC to DC converter, and on-board diagnostics to indicate snubber failures and abnormal conditions of the self-powered supply.

Abstract: A switching power supply includes: a first switch provided between one end of a DC power supply and one end of a load; a second switch provided between a node of the first switch located on a load side and another end of the DC power supply; a capacitor provided between the second switch and the another end of the DC power supply; a third switch provided between a node of the first switch located on a DC power supply side and a node between the second switch and the capacitor; and a delay circuit that is provided between the third switch and the node between the second switch and the capacitor and delays a current for charging the capacitor, wherein the second switch is turned on in a period during which the first switch is kept on.

Abstract: A flyback converter having an active snubber includes a transformer to receive input power. The transformer has a primary winding at a first side. The active snubber is coupled in parallel with two ends of the primary winding and has a first circumferential circuit coupling in parallel with the primary winding, a second circumferential circuit and a zero voltage switch unit. The second circumferential circuit is controlled by the zero voltage switch unit and incorporated with the first circumferential circuit to form double damping paths to reduce current and prevent resonance that might otherwise occur to a single circumferential circuit and the secondary side of the transformer.

Abstract: A matrix converter may be provided with AC switches that comprise bi-directional sets of semiconductor switches that are gated with a common gating link. A low loss diode-bridge based snubber may facilitate introduction of time delay between sequential operations of the bi-directional set of semiconductor switches. The matrix converter may be operated in a three-phase mode with only one gating signals for each AC switch, in contrast to prior-art matrix converters which may require use multiple gating signals for each AC switch.

Abstract: A protection scheme to protect pulse width modulated drives is described. The scheme is implantable in both hardware and software and combinations thereof. The semiconductor devices of the drive are protected from transient signals such as power line spikes and loss of line. The present scheme uses an adaptive technique to determine the normal or steady state distortion (transients and harmonics) value in an unfiltered power signal. The present distortion value is compared to the normal distortion. If the present distortion exceeds the steady state value by a given amount, then the drive is placed in freewheel mode to protect the semiconductor devices in the drive.

Abstract: The present invention provides a switching power supply device including a switching element, a control circuit controlling the switching element, a transformer having an auxiliary winding, a potential clamp circuit connected to one of outputs of the transformer, a delay capacitor connected to an output of the potential clamp circuit, a potential detection circuit detecting a potential at the delay capacitor, and an overload protection actuation circuit realizing overload protection. During an overload, the delay capacitor is charged only by ringing of the auxiliary winding, generated immediately after the switching element is turned off, through the potential clamp circuit. Then, the potential detection circuit supplies an actuation signal to a latch stop circuit by detecting that the potential at the delay capacitor rises. The latch stop circuit latches and stops the switching operation of the switching element to realize the overload protection when the actuation signal is fed into the latch stop circuit.

Abstract: A protection scheme to protect pulse width modulated drives is described. The scheme is implantable in both hardware and software and combinations thereof. The semiconductor devices of the drive are protected from transient signals such as power line spikes and loss of line. The present scheme uses an adaptive technique to determine the normal or steady state distortion (transients and harmonics) value in an unfiltered power signal. The present distortion value is compared to the normal distortion. If the present distortion exceeds the steady state value by a given amount, then the drive is placed in freewheel mode to protect the semiconductor devices in the drive.

Abstract: An AC/DC power supply with over-voltage protection includes a voltage converting circuit and a digital latch control circuit. The voltage converting circuit has a first-side winding, a second-side winding, and an auxiliary winding for providing a supply voltage according to the AC input voltage. The digital latch control circuit is coupled to the voltage converting circuit and utilized for latching a voltage level of the supply voltage at a first predetermined level according to an over-voltage protection (OVP) trigger signal, where the voltage converting circuit is disabled when the voltage level is latched at the first predetermined level.

Abstract: A circuit arrangement for limiting excessive voltages by a forward delay time of a first diode is described. The first diode is alternately switched in a non-conducting direction and a conducting direction by switching a circuit element. The first diode is series-connected to a first capacitor and a pre-charging circuit is provided for the first capacitor, the pre-charging circuit charging the first capacitor while the first diode is switched in the non-conducting direction. The pre-charging circuit charges the first capacitor more strongly than an excessive voltage of the first diode with regard to the amount.

Abstract: An amplifier is driven by DC voltage from a switchmode power supply, whereby the switchmode power supply includes on the primary side a primary winding and bias supply winding. The bias supply winding supplies a reflected voltage from a secondary winding to a bias supply capacitor. The bias supply capacitor drives the control circuit and provides a sensing to the control circuit. The power supply further includes an active clamp circuit for controlling the voltage stress on a main switch. In another embodiment, boost inductors and a balancing transformer are added on the primary side of the transformer to prevent overvoltage conditions at light loads.

Abstract: The present invention provides an inverter circuit for a vehicle, which includes: a switching unit that includes a plurality of switching elements and switches a direct current into an alternating current; and a variable clamping unit that clamps an overshoot in case the overshoot is generated, and stops the operation of the switching unit in case a system voltage is greater than a clamping breakdown voltage. The circuit enables a voltage (DC input voltage) greater than a breakdown voltage of clamping unit to be used as a system voltage.

Abstract: A switching power supply controller has a nominal loop gain and transient loop gain that is only activated in response to an abrupt load change in one direction. The transient loop gain may be implemented with a series-connected diode and resistor combination arranged in a feedback configuration with an error amplifier. A large load change in one direction may swing the output of the error amplifier and forward bias the diode to create a non-linear gain change.

Abstract: A cycle modulation circuit for limiting voltage peak value of a power supply employed an active clamp. The power supply receives an input power which is modulated through a power driving unit to become a driving power transformed through a transformer to be output. The cycle modulation circuit includes a comparison unit and a linear voltage generation unit. The comparison unit receives the input power to generate a level signal which is used as a base value to compare level with an oscillation signal generated by the linear voltage generation unit, thereby to modulate and output a pulse width limit signal with a composite cycle consisting of a high level and a low level. The pulse width limit signal is input to the power driving unit to limit the peak value of the driving power modulated by the power driving unit.

Abstract: A flyback converter with a leakage-inductance energy recycling circuit includes a transformer and a leakage-inductance energy recycling circuit. The leakage-inductance energy recycling circuit includes a clamping circuit, an energy storage circuit, and a switch connected between the clamping circuit and the energy storage circuit. A power transistor is electrically connected to a primary winding of the transformer. The clamping circuit clamps the voltage of the power transistor at a predetermined voltage. The energy storage circuit stores the leakage-inductance energy of the primary winding. When the switch is turned off, the clamping circuit receives and stores the leakage-inductance energy of the primary winding, so as to clamp the voltage of the power transistor to a predetermined voltage; when the switch is turned on, the energy stored in the clamping circuit is stored in the energy storage circuit through the switch.

Abstract: The present switch mode power converter having multiple inductor windings equipped with snubber circuits uses a small value inductor that has at least one properly oriented secondary winding, and ultra fast diodes interconnect the primary and the secondary windings of this inductor for providing protection against momentary short circuits, reductions of dv/dt, and switching losses.

Abstract: Self-powered supplies are presented for powering a power converter switch driver with power obtained from an associated snubber circuit, in which a supply circuit and a snubber circuit are connected in a series path across the switch terminals with the supply circuit receiving electrical power from the snubber and providing power to the switch driver.

Abstract: An inverter device includes an inverter circuit, an inverter driving unit, and a clamp diode. The inverter circuit includes an upper arm unit and a lower arm unit connected in series. The upper arm unit and the lower arm unit include switching elements that drive a load. The inverter driving unit includes a high-withstand-voltage IC that drives the switching elements of the upper arm unit and the lower arm unit. The high-withstand-voltage IC has a first terminal for supplying a reference voltage to the lower arm unit and a second terminal for supplying a high-voltage to the upper arm unit. The clamp diode clamps a potential difference between the first terminal and the second terminal.

Abstract: An improved snubber is electrically switched to close a current path to a capacitor (C) in a series connected RC circuit at the onset of an abrupt voltage change otherwise producing ringing in a resonant circuit to which the snubber circuit is connected. The current path to the capacitor (C) is then interrupted before the capacitor (C) discharges and thereafter at each such voltage change in the resonant circuit the capacitor (C) is no longer charged from its totally discharged state but nevertheless damps the ringing by virtue of current flow to the nearly completely charged capacitor (C). By preventing complete charging and discharging of the capacitor (C) in the RC circuit every cycle, power dissipation in the resistance of the snubber circuit is greatly reduced.

Abstract: A snubber circuit and corresponding power converter topology for controlling the voltage across the resonant capacitor at turn on of a control switch so as to suppress a spike at the switch caused by the large current pulse and parasitic inductance of the power converter. The suppression of the spike reduces conduction losses and increases efficiency. According to one embodiment, the snubber circuit in a boost converter topology includes a second winding tapped from the main boost inductor and connected in series with a first diode and a second diode. A resonant capacitor and the second diode are connected in a series combination which is in parallel with the main boost diode. The second winding is connected in series with the first diode and the second diode between the output terminals of the converter. Alternatively, the snubber circuit is used in flyback, buck, and forward converter topologies.

Abstract: For use in a power converter having parallel power trains, a circuit for, and method of, reducing voltage spikes due to magnetizing current imbalances in the power trains and a power converter incorporating the circuit or the method. In one embodiment, the circuit includes: (1) a conductive bypass path coupling nodes between transformer secondary windings and inductors in each of the power trains and configured to provide an alternative path to redirect magnetizing current imbalances from the inductors and (2) a capacitor located in the conductive bypass path.

Abstract: A DC-DC converter reduces a surge voltage developed across a switching element (30) in making the voltage conversion with the use of a transformer (20) inherently having considerable leakage. A snubber circuit is included to absorb the surge energy and transferring it to a load, or output end of the converter, reducing the surge voltage across the switching element (30). A snubber capacitor (51) is provided to absorb the surge energy developed by the transformer (20) when the switching element (30) is off. Thus absorbed energy is collected in a storage capacitor (53) through a reactor (54) while the switching element (30) is on and off, and is then transferred from the storage capacitor (53) to the load, i.e., the output side of the converter, leaving only a minimum voltage being applied across the switching element (30).

Abstract: A low acoustic noise solution for snubber circuits is utilized for relieving spike noise under a low-load mode of a snubber circuit, and for avoiding electromagnetic interference under a high-load mode of said snubber circuit. A power transform device utilizing the low acoustic solution includes a power source node, a switch node, a ground node, a transformer, a third switching unit, a first spike noise snubber circuit, a first switch unit, a second spike noise snubber circuit, and a second switch unit. When the power transform device is under the low-load mode, the first spike noise snubber circuit is used to absorb power discharged from the transformer so that spike noise is relived. When the power transform device is under the high-load mode, both the first and the second spike noise snubber circuits are used to absorb power so that electromagnetic interference is relieved.

Abstract: A protection scheme to protect pulse width modulated drives is described. The scheme is implantable in both hardware and software and combinations thereof. The semiconductor devices of the drive are protected from transient signals such as power line spikes and loss of line. The present scheme uses an adaptive technique to determine the normal or steady state distortion (transients and harmonics) value in an unfiltered power signal. The present distortion value is compared to the normal distortion. If the present distortion exceeds the steady state value by a given amount, then the drive is placed in freewheel mode to protect the semiconductor devices in the drive.

Abstract: A switching power source apparatus can reduce the size of a transformer and realize the zero-voltage switching of a switch. The apparatus is compact, highly efficient, and low in noise. The apparatus has a series circuit connected to each end of a DC power source (Vdc1) and including a primary winding (5a) of a transformer (T) and a main switch (Q1), a rectifying-smoothing circuit to rectify and smooth a voltage that is output from a secondary winding (5b) when the main switch (Q1) is turned on, a series circuit connected to each end of the primary winding (5a) and including an auxiliary switch (Q2) and a clamp capacitor (C1), a series circuit connected to each end of the primary winding (5a) and including an auxiliary reactor (Lx), a diode (Dx1), and a snubber capacitor (Cx), a series circuit connected to each end of the auxiliary switch (Q2) and including a diode (Dx2) and the snubber capacitor (Cx), and a control circuit (10) to alternately turn on/off the main switch (Q1) and auxiliary switch (Q2).

Abstract: A new type of the passive non-dissipative snubber with a single saturable reactor improves the performance of the boost converter used as a front-end active Power Factor Correction (PFC) in two critical areas: excess voltage stresses caused by high voltage spikes on input high voltage switching transistor of the boost converter is eliminated and EMI noise is much reduced. The high voltage spike energy instead of being dissipated as in a dissipative snubber circuits is recovered resulting in increased conversion efficiency. High voltage spike elimination also allows use of lower voltage rated devices with lower ON resistance, hence further increasing the efficiency of the PFC boost converter.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A solid state switching circuit utilizes a transformer in series with the circuit's switching device by which energy initially stored in the primary of the transformer is recovered in resonant circuitry connected to the secondary of the transformer for transfer of the energy to the load when the switching device is not conducting.

Abstract: A DC/DC power supply with two transformers (10, 20), which for example are connected in parallel on the primary and in series on the secondary side, comprises two passive, non-dissipative snubber circuits (1.1, 1.2). Each snubber circuit comprises a series circuit formed by a capacitor (3.1, 3.2) and a diode (4.4, 4.7), which is connected to the output capacitor (13) of the power supply. The transformers are interleaved with a push-pull configuration. On the secondary side, the power supply has an output choke (12, 22) and two output rectifiers (11, 21) are connected to the secondary winding (14, 24) of each transformer. Each snubber circuit further comprises two additional diodes (4.5, 4.6, 4.8, 4.9), one electrode of these diodes being connected to the joint electrode of the snubber capacitor (3.1, 3.2) and the first snubber diode (4.4, 4.7) and the other electrodes being connected respectively to an end of the secondary winding (14, 24) of a transformer.

Abstract: A switching power source apparatus can reduce the size of a transformer and realize the zero-voltage switching of a switch. The apparatus is compact, highly efficient, and low in noise.

Abstract: FA ballast (20) for powering a gas discharge lamp (70) comprises an inverter (200) and an arc protection circuit (600). Arc protection circuit (600) monitors an electrical signal within the ballast. In response to occurrence of a disturbance in the signal, such as what occurs during output arcing, arc protection circuit (600) disables the inverter (200) for a timed shutdown period. Arc protection circuit (600) provides a timed starting period for igniting the lamp, during which time any disturbance in the electrical signal is essentially ignored and inverter (200) is allowed to continue to operate. Arc protection circuit (600) also provides a restart function for periodically attempting to ignite and operate the lamp. Arc protection circuit (600) is preferably realized using a timer integrated circuit (U1) with associated discrete circuitry, and may be adapted for use with ballasts having self-oscillating or driven type inverters.

Abstract: A SEPIC type voltage converter (101) comprises a transformer (40) having a primary winding (41) and a storage capacitor (33) connected in series, and a controllable switch (51) coupled in parallel with said series combination. The transformer has a first secondary winding (421) and a first rectifying diode (431) connected in series, and a first capacitor (441) coupled in parallel with said series combination, one terminal of said first capacitor (441) being coupled to an output terminal (451). The voltage converter also comprises feedback means (50; 53, 52) coupled to said output terminal (451) and controlling said controllable switch (51). The transformer further has a second secondary winding (62) and a second rectifying diode (63) connected in series, wherein this series combination is also coupled to said output terminal (451) in order to limit the voltage across the storage capacitor.

Abstract: The invention relates to a unitary magnetic coupler including a first inductor (Lp) consisting of a first winding of phase ? and having a number N of turns between the two ends of the first winding and, magnetically coupled to the first inductor (Lp), a second inductor (Ls) consisting of a second winding of the same phase ? and having the same number N of turns between the two ends of the second winding, where the ends of the first and second windings of the unitary magnetic coupler are interconnected using links consisting of capacitors (C1, C2) of equal value.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: An unregulated DC-to-DC power converter suitable for intermediate bus voltage converter applications includes synchronous rectifiers that are driven efficiently to provide faster transition time and reduced loss. The DC-to-DC power converter comprises a transformer having a primary winding and at least first and second secondary windings. An input circuit is coupled to the primary winding and is adapted to apply an alternating polarity square wave voltage to the primary winding. An output circuit comprising an output filter is coupled to a tap of the first secondary winding. The output filter provides a DC output voltage. A first synchronous rectifier is coupled to a first end of the first secondary winding and a second synchronous rectifier is coupled to a second end of the first secondary winding. The second secondary winding has a first end coupled to a control terminal of the first synchronous rectifier and a second end coupled to a control terminal of the second synchronous rectifier.

Abstract: Method and apparatus for controlling a DC-DC converter change the switching frequency of the switching devices and the on-off ratio of the switching devices. The on-off ratio can be changed in response to the output voltage and the switching frequency can be changed in response to the input voltage supplied by the DC power supply. Alternatively, the switching frequency can be changed while the on-off ratio is fixed at a certain value, and the on-off ratio can be changed while the switching frequency is fixed at a predetermined value after the switching frequency has reached the predetermined value, thereby preventing the switching frequency from exceeding the predetermined value.

Abstract: The invention relates to a VSC-converter for converting direct voltage into auxiliary voltage and vice versa, which comprises a series connection of at least two current valves (5, 6) arranged between two poles (7, 8), a positive and a negative, of a direct voltage side of the converter, each current valve comprising several series connected circuits (12), each of which circuits comprising a semiconductor component (13) of turn-off type and a rectifying component (14) connected in anti-parallel therewith, an alternating voltage phase line (16) being connected to a midpoint (15), denominated phase output, of the series connection of current valves (5, 6) between two of said current valves while dividing the series connection into two equal parts.

Abstract: The present invention is directed to an auxiliary active clamp circuit and a method of clamping a voltage of a rectifier switch associated with a power converter. The power converter includes a main active clamp circuit associated with a main power switch coupled to a primary winding of a transformer and a rectifier switch coupled to a secondary winding of the transformer. The main power switch conducts during a main conduction period of the power converter and the rectifier switch conducts during an auxiliary conduction period of the power converter. In one embodiment, the auxiliary active clamp circuit includes an auxiliary clamp capacitor, coupled across the rectifier switch, that stores a clamping voltage substantially equal to an off-state voltage of the rectifier switch.

Abstract: A primary-side flyback power converter supplies a constant voltage and a constant current output. To generate a well-regulated output voltage under varying load conditions, the power converter includes a PWM controller. The PWM controller generates a PWM signal to control a switching transistor in response to a flyback voltage detected from the first primary winding of the power supply transformer. To reduce power consumption, the flyback energy of the first primary winding is used as a DC power source for the PWM controller. The flyback voltage is sampled following a delay time to reduce interference from the inductance leakage of the transformer. To generate a more accurate DC output voltage, a bias current is pulled from the detection input to form a voltage drop across a detection resistor for compensating for the voltage drop of the output rectifying diode.

Abstract: The present invention provides a primary-side flyback power converter that supplies a constant voltage output and a constant current output. To generate a well-regulated output voltage under varying load conditions, a PWM controller is included in the power converter in order to generate a PWM signal controlling a switching transistor in response to a flyback voltage sampled from a first primary winding of the power supply transformer. Several improvements are included in this present invention to overcome the disadvantages of prior-art flyback power converters. Firstly, the flyback energy of the first primary winding is used as a DC power source for the PWM controller in order to reduce power consumption. A double sample amplifier samples the flyback voltage just before the transformer current drops to zero. Moreover, an offset current is pulled from a detection input of the double sample amplifier in order to generate a more accurate DC output voltage.

Abstract: The invention relates to a converter provided with a resonant circuit (16), which converter comprises a device (31) for measuring the derivative (dI/dt) of the current through the current valves 82, 3) and a detection device (32) co-operating with said measuring device (31) for detecting a short-circuit in the converter, the detection device (32) being adapted to detect a short-circuit current when the current derivative (dI/dt) measured by the measuring device (31) is equal to or exceeds a stipulated current derivative limit value (dI/dtlim) during a length of time exceeding a stipulated time limit value (tlim). The invention also relates to a method for controlling such a converter.

Abstract: Dissipative clamping apparatuses and methods for electrical circuits. In one aspect of the invention, In one aspect of the invention, a method includes switching a power supply input on an energy transfer element, regulating a power supply output by switching the power supply input on the energy transfer element, clamping a voltage on the energy transfer element to a clamp voltage and varying the clamp voltage in response to the power supply input. In another aspect, an electrical circuit includes a dissipative clamp circuit coupled to an input of the electrical circuit. An inductive element is coupled between the dissipative clamp circuit and an output of the electrical circuit. A switch is coupled in series with the inductive element.

Abstract: A power supply circuit for a video display device including a power transformer for inducing a voltage with respect to an input voltage by using an interaction occurring between a primary coil and a secondary coil; a switching circuit unit for controlling the voltage to be induced at the secondary coil of the power transformer by switching on/off a current flowing along the primary coil of the power transformer; first and second TVS diodes serially connected to each other; first and second resistors parallel connected to the respective first and second TVS diodes; a capacitor parallel connected to both ends of the first and second TVS diodes connected to each other and being charged with the transient voltage in the reverse direction that is supplied through the primary coil of the power transformer; and a diode for forming a passage of current in one direction when the capacitor is charged.

Abstract: A method and apparatus for providing welding-type power supply is disclosed. It includes an inverter power circuit, a bus inductor, a snubber circuit a snubber capacitor voltage feedback circuit, and a control circuit. The inverter circuit includes a bus, switches, and an output. The bus inductor is connected to the inverter and the bus. The snubber circuit is connected to the switches. Also, the snubber circuit includes a snubber inductor, a snubber capacitor, a recovery switch connected to the snubber inductor and the snubber capacitor. At least one freewheeling circuit includes the snubber inductor and at least one freewheeling switch. The snubber capacitor voltage feedback circuit is connected to the snubber capacitor and provides a snubber capacitor voltage feedback output to the control circuit. The control circuit includes a comparison circuit that compares the snubber capacitor voltage feedback and a threshold. The output of the comparison controls the recovery switch.

Abstract: Voltage regulation, transient response and efficiency of a voltage regulator module (VRM) is improved where short duty cycles are necessitated by large differentials of input and output voltage by including at least one clamping of a tap of an inductance in series with an output of each of a plurality of parallel branches or phases which are switched in a complementary fashion or providing coupling between inductors of respective phases. Such coupling between inductors is achieved in a small module with an integrated magnetic structure. Reduced component counts are achieved while deriving built-in input and output filters. Principals of the invention can be extended to isolation applications and push-pull forward converts, in particular. A lossless clamping circuit is also provided allowing spike currents to be suppressed while returning power to the output of the VRM.

Abstract: The present invention provides a primary-side flyback power converter that supplies a constant voltage output and a constant current output. To generate a well-regulated output voltage under varying load conditions, a PWM controller is included in the power converter in order to generate a PWM signal controlling a switching transistor in response to a flyback voltage sampled from a first primary winding of the power supply transformer. Several improvements are included in this present invention to overcome the disadvantages of prior-art flyback power converters. Firstly, the flyback energy of the first primary winding is used as a DC power source for the PWM controller in order to reduce power consumption. A double sample amplifier samples the flyback voltage just before the transformer current drops to zero. Moreover, an offset current is pulled from a detection input of the double sample amplifier in order to generate a more accurate DC output voltage.