Abstract: A power converter controller is disclosed. An example controller includes a control circuit coupled to receive a feedback signal representative of an output of the power converter. The control circuit coupled to control a switching of a power switch of the power converter in response to the feedback signal to control a transfer of energy from an input of the power converter to the output of the power converter. An internal programming interface circuit is coupled to the control circuit. A coupling switcher is coupled to the internal programming interface circuit. An external programming terminal is selectively coupled to the internal programming interface circuit through the coupling switcher. An external programming circuit coupled to the external programming terminal is coupled to the internal programming interface circuit through the coupling switcher during a startup programming condition and during a fault condition of the power converter.

Abstract: An inverter includes a multilevel bridge circuit. A control circuit is operatively coupled to the multilevel bridge circuit and configured to detect an overcurrent for an output of the inverter, to generate a measure of a duration of the overcurrent and to selectively put an output of the bridge circuit in a first impedance state or a second impedance state based on the measure. The first and second impedance states may provide respective first and second impedances between the bridge circuit output and a neutral.

Abstract: A power conversion device includes: an inverter that converts a DC current supplied from a DC power source to an AC current by engaging a plurality of switching elements, which constitute an upper arm, and a plurality of switching elements, which constitute a lower arm, in switching operation; a control unit that includes a signal generation unit that generates a switching signal carrying a command for execution of the switching operation in correspondence to each of the plurality of switching elements constituting the upper arm and the plurality of switching elements constituting the lower arm, and outputs the switching signal thus generated as a control signal; and a drive unit that individually drives each of the switching elements based upon the corresponding control signals.

Abstract: According to one embodiment, an electronic device includes a positive electrode, a negative electrode, a first terminal, a second terminal, a first plurality of switching elements and anti-parallel diodes coupled between the positive electrode and the first terminal and the second terminal, a second plurality of switching elements and anti-parallel diodes coupled between the negative electrode and the first terminal and the second terminal and a PiN diode coupled between the positive electrode and the negative electrode with reverse polarity.

Abstract: To make it possible to avoid an unstable state with a simple configuration even one of the phases of the motor fails. A motor drive system in accordance with the present invention includes a motor to which a plurality of phase coils of five phases or more are connected in a star connection, an inverter connected to one end of each of the phase coils, the inverter being configured to convert a DC power into an AC power and supply the AC power to each phase of the motor, a power relay disposed at another end of each of the phase coils, the power relay being configured so as to be able to cut off a supply power to at least one phase coil among the plurality of phase coils of the motor by using a plurality of contact points interposed between the star-connected coils, and a control unit that generates a control signal for the inverter and thereby controls driving of the motor.

Abstract: System and method for protecting a power converter. The system includes a duty-cycle detection component configured to receive a modulation signal, determine a first duty cycle corresponding to a first period of the modulation signal, compare the first duty cycle with a threshold duty cycle, and generate a duty-cycle comparison signal. Additionally, the system includes a threshold generator configured to receive the duty-cycle comparison signal and generate a threshold signal corresponding to a second period of the modulation signal, the second period being after the first period, and a comparator configured to receive the threshold signal and a first signal and to generate a first comparison signal. The first signal is associated with an input current for a power converter. Moreover, the system includes a pulse-width-modulation component configured to receive the first comparison signal and generate the modulation signal for adjusting the input current for the power converter.

Abstract: An electronic device for DC-DC conversion of an input voltage into an output voltage is provided. The electronic device includes a current mode control loop for controlling a sensed current of the DC-DC conversion by comparing a voltage level indicating a magnitude of the sensed current with a reference voltage level indicating the maximum admissible magnitude of the sensed current. The reference voltage level is dynamically adjusted in response to a change of an input voltage level.

Abstract: Some of the embodiments of the present disclosure provide an apparatus comprising a voltage sensor circuit configured to generate a voltage feedback signal indicative of an output voltage of the apparatus, a current sensor circuit configured to generate a current feedback signal indicative of a load current of the apparatus, a converter configured to receive the current feedback signal, and generate a fault signal that is indicative of a fault condition associated with the load current, and an optocoupler configured to receive the voltage feedback signal and the fault signal, and generate a feedback signal that is indicative of the output voltage and indicative of the fault condition. Other embodiments are also described and claimed.

Abstract: A power conversion device includes an inverter for converting DC power to AC power to supply the AC power to a load, a converter for converting AC power from an AC power supply to DC power to supply the DC power to the inverter, a DC voltage converter for converting a voltage value of power stored in a storage battery to supply DC power from the storage battery to the inverter when power supply by the AC power supply is abnormal, and a filter which includes a reactor and a capacitor and removes harmonics generated by the inverter. The inverter includes a three-level circuit constituted of an arm and an AC switch.

Abstract: An open loop half-bridge power converter is provided for effective zero volt switching during all operating conditions, the converter including: an oscillating inverter circuit having a pair of switches coupled to a load circuit; an inverter drive circuit effective to provide driver signals to the inverter circuit; and a control circuit for providing control signals to the drive circuit. The control circuit is configured to increase a switching frequency of the switching devices in response to a predetermined condition such as startup or short circuit conditions. The inverter as a result continues to operate at a full duty cycle in response to the increased switching frequency, and zero volt switching is ensured throughout the duration of the predetermined condition.

Abstract: Voltage source converter based on a chain-link cell topology including one or more phases, each of the phases having one or more series-connected chain-link cell modules connected to each other. The output voltage of the voltage source converter is controlled by control signals applied to the series-connected chain-link cell modules. In case of failure of a chain-link cell module, that module is controlled, by the control signals, such that zero output voltage is provided at its output voltage AC terminal.

Abstract: A three-phase inverter circuit includes an inverter incorporating a plurality of controllable power switches, and an electronic control device adapted to control the power switches. The control device in the event of a measured voltage drop on one phase is adapted to supply a reactive current on the phase with voltage drop and to supply and/or draw an active current on at least one phase without voltage drop.

Abstract: A switching power supply includes a rectifier circuit, a converter, a detecting unit, a control unit, a switching unit, and a protection unit. The rectifier circuit is used for rectifying an input voltage into a first direct current voltage. The converter is configured for generating a first current according to the first direct current voltage. The detecting unit is used for generating a detected voltage according to the first current. The control unit is configured for generating a control signal. The switching unit is used for enabling the converter, and conducting the first current to the detecting unit when receiving the control signal. The protection unit is configured for shunting the first current with the detecting unit when the first current becomes a large current surge. The control unit stops generating the control signal when determining that the detected voltage is equal to or higher than a predetermined value.

Abstract: The present invention is to provide a series resonant converter with an overload delay and short-circuit protection mechanism, which includes a voltage sensing circuit for sensing a voltage ripple level on a primary side of a transformer thereof, that corresponds to a load on a secondary side of the transformer, and generating and sending a DC detection level to an overload delay circuit and a short-circuit protection circuit thereof accordingly. The overload delay circuit and the short-circuit protection circuit are able control the converter through a resonant controller chip to output different currents according to magnitude of the load on the secondary side and maintain stable operation for a predetermined delay time even if the secondary side is overloaded, however, once the secondary side is short-circuited, the converter is turned off instantly. Thus, the converter is effectively prevented from damage which may otherwise result from sustained overload or short circuit.

Abstract: A switch control circuit for controlling a bridge circuit comprising: an upper and a lower transistor, connected to a positive and a negative voltage, respectively, and comprising a flywheel diode connected in parallel with each transistor. An LC-circuit filters the voltage from the junction of the transistors. A drive circuit controls each transistor in order to switch off the corresponding switch element when a reference current has been obtained in the inductor and for switching on the corresponding switch element when the current in the inductor is essentially zero. A first timer circuit is arranged for preventing the on-switch of the switch element until a minimum time period has passed.

Abstract: A protected power conversion device (1) includes a full-bridge MERS (100), a control circuit (200), and an ammeter (300), and is connected between a DC current source (2) and an inductive load (3). The ammeter (300) measures a current value supplied to the inductive load (3). The control circuit (200) changes the states of four reverse-conductive semiconductor switches (SW1) to (SW4) configuring the full-bridge MERS (100) to convert power output by the DC current source (2) into AC power, and supplies the AC power to the inductive load (3). When, for example, the inductive load (3) is short-circuited and malfunctions, a large current flows therethrough, and the current value detected by the ammeter (300) becomes equal to or greater than a predetermined value, the control circuit (200) turns OFF all reverse-conductive semiconductor switches (SW1) to (SW4) to cut OFF the large current.

Abstract: A system and method for digital management and control of power conversion from battery cells. The system utilizes a power management and conversion module that uses a CPU to maintain a high power conversion efficiency over a wide range of loads and to manage charge and discharge operation of the battery cells. The power management and conversion module includes the CPU, a current sense unit, a charge/discharge unit, a DC-to-DC conversion unit, a battery protection unit, a fuel gauge and an internal DC regulation unit. Through intelligent power conversion and charge/discharge operations, a given battery type is given the ability to emulate other battery types by conversion of the output voltage of the battery and adaptation of the charging scheme to suit the battery.

Abstract: A power supply controller is disclosed. An example power supply controller includes an input voltage sense input coupled to sense an input voltage sense signal representative of an input voltage of a power supply. An output voltage sense input is coupled to sense an output voltage sense signal representative of an output voltage of the power supply. A current limit circuit is coupled to generate a current limit signal. The current limit signal is varied relative to a first ratio representative of a ratio of a product of the input voltage and a scaled output voltage of the power supply, to a sum of the input voltage and the scaled output voltage of the power supply. A drive signal generator is coupled to generate a drive signal in response to the current limit signal to drive the power switch of the power supply to limit an output power of the power supply in response to the input voltage.

Abstract: An electric power transmission system includes at each end of a high voltage direct current transmission line including three conductors, a converter station for conversion of an alternating voltage into a direct voltage for transmitting direct current between the stations in all three conductors. Each station has a voltage source converter and an extra phase leg connected between the two pole conductors of the direct voltage side of the converter. A third of the conductors is connected to a midpoint between current valves of the extra phase leg. An arrangement is adapted to control the current valves of the extra phase leg to switch for connecting the third conductor either to the first pole conductor or the second pole conductor for utilizing the third conductor for conducting current between the stations.

Abstract: The voltage of a detection resistor connected to the drain of a low-side switching device is normally a negative voltage, but a positive voltage appears when a countercurrent occurs in an abnormal state. A current comparator monitors the voltage of the detection resistor, transmits high output to an AND circuit whole the voltage of the detection resistor is a negative voltage to maintain the output voltage of the current comparator in a low state when an output signal of a driver can be transmitted to the low-side switching device, and allows the output voltage of the current comparator in a low state when the voltage of the detection resistor becomes a positive voltage, thereby forcibly turning off the low-side switching device.

Abstract: A DC motor is provided. The DC motor prevents rush or overload of current in the DC motor during and/or after power input irregularities to the DC motor. A control circuit of the DC motor is configured to control current provided to the DC motor. When power irregularities in the power input to the DC motor are detected by the control circuit, the control circuit stops generating PWM (Pulse Width Modulated) signals and stops the current provided to the DC motor. After the stoppage of PWM signals, the control circuit can perform a soft-start of the PWM signals when the power irregularities are no longer detected. The soft starting of the PWM signals generates gradual increase in current to the DC motor, thus, preventing sudden rush of current that cause malfunction of the DC motor.

Abstract: An embodiment of the invention provides a surge current protection circuit. The surge current protection circuit comprises a peak current detector and a current sensing device. When the peak current detector detects when a surge current has occurred, by monitoring a change in duty cycle on a node of a HS (high side) switch, a LS (low side) switch is activated. The current sensing device senses the current drawn through the LS switch. When the current sensing device senses a current that exceeds a current limit, the HS switch is turned off for a period of time such that the surge current is reduced.

Abstract: A battery pack includes at least one secondary battery, a fuse, and a control section. The fuse is configured to cut off charge or discharge current of the secondary battery upon detection of an abnormality of the secondary battery. The control section is configured to detect the abnormality of the secondary battery, and to perform a fusion-cutting process of fusion-cutting the fuse in accordance with the result of the detection. Upon detection of the abnormality, the control section measures a first potential being the potential of a subsequent stage of the fuse and a second potential being the potential of the secondary battery. If it is found from the result of the measurement that the first potential and the second potential are equal, the control section determines that the fuse has not been fusion-cut by the fusion-cutting process, and stops the fusion-cutting process.

Abstract: The present invention discloses an overvoltage protection (OVP) circuit for use in a charger circuit system, comprising: a power transistor electrically connected between a voltage supply and a battery; an OVP circuit which turns off the transistor when a voltage supply exceeds a threshold value; and a multiplexing circuit electrically connected between an output of the OVP circuit and the gate of the transistor. The present invention also discloses a charger circuit with an OVP function, comprising: a single power transistor electrically connected between a voltage supply and a battery; an OVP control circuit which turns off the power transistor when a voltage supply exceeds a threshold value; and a charger control circuit which controls the gate of the power transistor to determine a charge current to the battery when the voltage supply does not reach the threshold value.

Abstract: When a battery pack, comprising an overcurrent protection section for stopping, when a current greater than a first threshold value passes, a current supply, is connected to a power supply terminal of an information processing apparatus, the information processing apparatus draws a current greater than the first threshold value. Thereafter, an output current and output voltage of the battery pack are detected, thereby measuring a time period from when a current drawing section draws the current greater than the first threshold value to when the battery pack stops the current supply. When the measured time period is within a first predetermined time range, the battery pack is permitted to supply an electric power. On the other hand, when the measured time period is not in the first predetermined time range, the battery pack is prohibited from supplying the electric power.

Abstract: Voltage source converter based on a chain-link cell topology including one or more phases, each of the phases having one or more series-connected chain-link cell modules connected to each other. The output voltage of the voltage source converter is controlled by control signals applied to the series-connected chain-link cell modules. In case of failure of a chain-link cell module, that module is controlled, by the control signals, such that zero output voltage is provided at its output voltage AC terminal.

Abstract: Methods and apparatus are provided for operation of a voltage source inverter. A method of operating a voltage source inverter having an output with multiple voltage phases having a DC voltage level, the method comprising sensing a low output frequency condition; determining a DC voltage offset responsive to the low output frequency condition; and applying the DC voltage offset when operating the voltage source inverter resulting in a change to the DC voltage level of the multiple voltage phases.

Abstract: An inverter controller comprising an AC motor as a load. A rectifying circuit converts AC power from an AC power source into DC power. A smoothing capacitor smoothens a DC voltage from the rectifying circuit. An inverter circuit converts DC power supplied via the smoothing capacitor into a desired frequency. A current detection circuit detects a output current of the inverter circuit. A voltage detection circuit detects a terminal voltage (Vpn) of the smoothing capacitor. A voltage command calculation circuit calculates a voltage command to the AC motor. A speed command calculation circuit calculates a speed command to be used when it is determined that the AC power source is in a power failure state or when the terminal voltage (Vpn) reaches a certain value.

Abstract: An electric circuit for supplying power to a DC application is disclosed. The electric circuit comprises a DC power source (1) connectable to an alternator charging circuit (2), an FET (T7), and a capacitor (8) connected across the gate terminal and the source terminal of the FET (T7). The drain terminal of the FET (T7) is connected to a negative terminal of the DC source (1). The FET (T7) protects the circuit against accidental connection of the alternator charging circuit (2) to the DC power source (1) with reversed polarity, by opening a switch (6) of the FET (T7) when this occurs. The capacitor (8) protects the FET (T7) from being pushed into avalanche in case a load-dump transient occurs. This is because the capacitor (8) in this case will charge and discharge, thereby introducing a time delay before the switch (6) is opened. Protection against load-dump transients is thereby obtained by means of a small component with low energy dissipation.

Abstract: In a rotary electric system, a switch member includes at least one of a first switch and a second switch. The first switch is connected between a neutral point of multiphase stator windings and a high-side electrode of a direct current power source. The second switch is connected between the neutral point and a low-side electrode of the direct current power source. A controller works to turn the switch member off and on thereby switching control of the multiphase inverter between full-wave driving mode and half-wave driving mode. The full-wave driving mode allows the controller to drive all of the high-side and low-side switching elements per phase of the multiphase stator windings. The half-wave driving mode allows the controller to drive any one of the high-side switching element and the low-side switching element per phase of the multiphase stator windings.

Abstract: If any short-circuit failure occurs in an inverter, then a motor generator is used to execute a safety driving. If the rotational speed of a motor generator calculated from a detection value of a position sensor exceeds a predetermined reference rotational speed during the safety driving, an MGECU turns on all of the switching elements connected in parallel to a switching element in which a short-circuit failure occurs with respect to a power supply line. If the rotational speed is equal to or less than the reference rotational speed, the MGECU turns on only the switching elements connected in series to the switching element in which the short-circuit failure occurs. In this way, any excessive currents can be prevented from occurring in the inverter without restricting the safety driving.

Abstract: An overcurrent detection circuit (50 in FIG. 1) in a DC-DC converter is connected to a switching control circuit (1), and detects an inductor current flowing through an inductor (L) during the ON control of a switching element (Mn), so as to decide whether the inductor current has decreased down to a prescribed value. The switching control circuit (1) alters the switching timing of a control signal to extend the OFF state of a switching element (Mp) until the decrease of the inductor current to a predetermined magnitude is decided by the overcurrent detection circuit (50). Even when a delay is involved in an overcurrent detection operation, the DC-DC converter is still capable of overcurrent limitation.

Abstract: Embodiments of systems and methods for powering a load are provided. In one embodiment, a method may include providing a power converter comprising electrical circuitry comprising at least a first leg and a second leg, supplying an input power signal to the power converter, supplying at least a first gating control signal to the first leg, supplying at least a second gating control signal to the second leg, and outputting at least one output power signal to the load responsive at least in part to the first and the second gating control signals supplied. According to this example embodiment, the first gating signal and the second gating signal may each comprise a waveform comprising a notch, and the second gating control signal may be phase shifted relative to the first gating control signal.

Abstract: A controller is provided for DC-DC converters of the type associated with a half-bridge driving stage of at least one inductive load, with a pair of power MOS transistors in Highside and Lowside configuration being driven by a corresponding converter. The controller includes an input for connection to a terminal of the inductive load. The controller also includes a read block for reading an inductive load phase current at the terminal, an over current comparator having a first input coupled to an output of the read block, and a bypass compensation network including an error amplifier block having a first input coupled to the terminal through a voltage divider, and a second input coupled to a reference potential. The compensation network has an output that is coupled to a second input of the over current comparator, and an output of the over current comparator is supplied to the DC-DC converter.

Abstract: Systems and methods for improved Variable Speed Drives are provided. One embodiment relates to apparatus for common mode and differential mode filtering for motor or compressor bearing protection when operating with Variable Speed Drives, including conducted EMI/RFI input power mains mitigation. Another embodiment relates to a method to extend the synchronous operation of an Active Converter to the AC mains voltage during complete line dropout. Another embodiment relates to an Active Converter-based Variable Speed Drive system with Improved Full Speed Efficiency. Another embodiment relates to a liquid- or refrigerant-cooled inductor. The liquid- or refrigerant-cooled inductor may be used in any application where liquid or refrigerant cooling is available and a reduction in size and weight of a magnetic component is desired.

Abstract: The invention relates to an alternating voltage generator (10) comprising a direct voltage source (20) that supplies a power bus, a bus capacitor (11) connected to the power bus, an inverter module (30) supplied by the power bus and equipped with several normally-on JFET power transistors (31a, 31b) in order to deliver an alternating voltage. The generator (10) comprises a current limiting normally-on JFET transistor (12) which is located on the power bus in series between the bus capacitor (11) and the inverter module (30), the limiting current of the limiting transistor (12) being less than the limiting current of each of the power transistors (31a, 31b).

Abstract: A transformer 6 and a photocoupler 5 are provided to ensure insulation between a primary side circuit section 10 connected to an alternating current power supply 2, and a secondary side circuit section 20 for applying a voltage to a lamp 4. A detection circuit section 22E, provided in the secondary side circuit section 20, detects an output voltage and an output current of the lamp 4 to detect a deviation from a predetermined power. A signal corresponding to the deviation, which has been detected by the detection circuit section 22E, is transmitted to the primary side circuit section 10 via the photocoupler 5 provided between the primary side circuit section 10 and the secondary side circuit section 20. A switching control section 13, provided in the primary side circuit section 10, carries out switching control for constant power lighting based on the signal transmitted from the photocoupler 5.

Abstract: A voltage sag generator device for use in an electrical generator machine such as a wind turbine, connected to an electrical network including one to three parallel transformers connected on one side to the wind turbine via a coupling switch and circuit breakers, and earthed on the other side via circuit breakers and a control switch. The device includes mechanisms for causing short-circuits when the coupling switch and the control switch are actuated in such a way that a voltage sag having the required duration and type is generated, and mechanisms for protecting the transformers during voltage sag generation.

Abstract: A light source is protected by selectively coupling a shunt path in parallel with the light source, such that current is diverted away from the light source and through the shunt path. A detection circuit detects the current flowing in the shunt path when the shunt path is connected in parallel with the light source. A comparator determines whether the current flowing in the shunt path exceeds a predetermined threshold and, if so, prevents or limits the flow of current when the shunt path is disconnected from being in parallel with the light source. In this way, a current detector is provided for monitoring the flow of current in a shunt path, the current detector being configured to disable or limit the flow of current through a light source when a predetermined threshold is reached.

Abstract: In a DC-DC converter of this invention, a voltage detection circuit is connected in parallel with an output switching device, and the voltage detection circuit is put into operation a predetermined time after the output switching device is turned on. In addition, a detection switching device, which constitutes the voltage detection circuit, is designed to have a higher ON resistance than an ON resistance of the output switching device.

Abstract: A programmable parameter or feature is provided for a power converter through a multi-function connection on the converter controller. The parameter or feature selection is active for programming during a startup mode, and the connection is used for other control purposes during a steady state run mode. A reference signal is read on the multifunction connection during startup mode and a selection of a parameter value or feature is made based on a value of the reference signal. The reference signal is compared to preset, internal reference values to select a desired parameter value or feature. An internal preset value is chosen based on the selection and the programming circuitry is disconnected from the connection to permit alternate functionality for the connection. The programmable circuit permits selection from a variety of parameter values or features based on an external signal, without dedicating an external pin on the controller.

Abstract: Provided is a flux regulation method for use in a power converter, wherein the method is carried out by a flux bias controller. The flux bias controller includes a current detector which is configured to detect the primary current of the transformer of the power converter in a predetermined switching cycle, a DC bias processor which is configured to obtain the duty ratio control signal according to the sampled primary current outputted from the current detector for a switching cycle later than the predetermined switching cycle, and a PWM controller which is configured to generate driving signals to control the on/off operations of the switching circuit of the power converter according to the duty ratio control signal, thereby suppressing the DC bias of the transformer by regulating the duty ratio of the switch 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 improved inductance-voltage clamping full-bridge soft-switch circuit including a full-bridge converter, a transformer, an output rectifying unit, an inductor, a clamping resistor, a capacitor, a first clamping diode, and a second clamping diode. The inductor includes a first winding used as an auxiliary inductor and a second winding used for clamping. A capacitor is connected in parallel with the clamping resistor connected in series.

Abstract: In a power switching circuit, a second commutation member has a second commutation path electrically connected in parallel to a first commutation path and a second diode provided in the second commutation path and electrically connected antiparallel to a semiconductor switching element. While the semiconductor switching element is off, the second commutation path allows a second current based on the inductive load to flow therethrough in a forward direction of the second diode within a commutation period. The second diode has a second reverse recovery time shorter than a first reverse recovery time of the first diode. A second inductance of the second commutation path is higher than a first inductance of the first commutation path.

Abstract: The present invention provides an inverter with a simple configuration capable of preventing occurrence of excessive rush current. A current detection circuit detects an AC output current flowing out from an output filter circuit. When the absolute value of the AC output current becomes equal to or larger than a threshold, a reset control unit and a drive pulse generation circuit control a DC/AC inverter so as to re-start operation after the AC output voltage becomes 0V. For example, even in the case where a capacitive load is connected during operation of the inverter or in the case where the load includes a standby circuit, excessive rush current is prevented.

Abstract: A method of operating a converter circuit is disclosed, wherein the converter circuit has a converter unit with a multiplicity of controllable power semiconductor switches and the converter unit is connected at the AC voltage end to an electrical AC voltage network. According to the method, the controllable power semiconductor switches are controlled by means of a control signal.

Abstract: Techniques are disclosed to detect a fault in the feedback circuit of a switching power supply while the power supply operates in a mode where the output is below its regulated value. The power supply delivers maximum power at a given switching frequency without a feedback signal while the output is below its regulated value. A fault protection circuit substantially reduces the average output power if there is no feedback signal for the duration of a fault time. When there is no feedback signal, the power supply increases the maximum output power by increasing the switching frequency before the end of the fault time to increase the output to a regulated value. The presence of a feedback signal when the output reaches a regulated value restores the original switching frequency and returns the output to its unregulated value. The absence of a feedback signal at the end of the fault time engages the fault protection circuit to substantially reduce the output power.

Abstract: Each of three-phase arm of an inverter has first and second switching elements connected in series together at a connection point to the corresponding phase coil of the three-phase motor. Control device turns on the first switching element of the i-th (i is a natural number smaller than four) for a predetermined time period, and determines that the second switching element of the i-th arm has a short fault, when an overcurrent exceeding a predetermined threshold is detected within the predetermined time period. The predetermined time period is shorter than a time period from a time point of turning on the first switching element of the i-th arm to a time point of attaining the predetermined threshold by a current flowing through a path extending from a power supply line through the second switching element of the remaining arm other than the i-th arm to a ground line.

Abstract: A device corrects the power factor in forced switching power supplies and includes a converter and a control device to obtain a regulated voltage on an output terminal. The control device comprises an error amplifier having an inverting terminal (Vout) and a non-inverting terminal receiving a reference voltage. The device includes first and second resistances coupled in series with a conduction element positioned between the first resistance and the inverting terminal of the error amplifier and a fault detector suitable for detecting the electrical connection of the conduction element with the output terminal and suitable for detecting an output signal of the second resistance. The fault detector is suitable for supplying a malfunction signal upon detecting an electric disconnection of the conduction element from the output terminal or when the output signal of the second resistance tends to zero.