298results about How to "Avoid Overvoltage Problems" patented technology

To avoid burning out a capacitor in a synchronous rectification type DC-to-DC converter due to overvoltages, the synchronous rectification type DC-to-DC converter includes a storage unit storing therein power derived from a power supply, switching elements connecting and disconnecting respective signal paths from power and ground, and a control unit controlling the connecting/disconnecting operations of the switching elements to maintain a voltage output from the storage unit at a predetermined value. The DC/DC converter also includes an overvoltage detecting unit monitoring a voltage derived from the power supply to thereby output an alarm signal when the voltage derived from the power supply exceeds a preselected voltage value, a shortcircuiting unit influencing the connecting conditions of the switching elements when the alarm signal from the overvoltage detecting unit is input therein, whereby the voltage derived from the power supply is shortcircuited, and an interrupting unit interrupting one of the signal paths by the power shortcircuited by the shortcircuiting unit.

The invention relates to an electric locomotive non-power-off neutral section passing-electric energy quality comprehensive compensation device and method, which belongs to the technical field of railway transport equipment and electric electronics. The device comprises a controllable transfer switch, a single-phase step down transformer, a single-phase step down transformer with a middle tap, a two-phase back-to-back converter sharing a DC-side capacitor, a circuit breaker switch, four position sensors and three electric quantity sensors. In the method, when the electric locomotive passes the neutral section, the controllable transfer switch is turned off, and the device works in a non-power-off neutral section passing mode to perform control on amplitude and phase of the neutral section voltage and enable the electric locomotive to pass the neutral section with load in a non-power-off manner. Without locomotive passing, the controllable transfer switch is closed, and the device works in an electric energy quality comprehensive compensation mode and has functions of active power transfer as well as inactive power and harmonic compensation. Through the device, the problems relating to electric energy quality of a traction substation and neutral section can be comprehensively solved based on the traditional traction power supply mode.

There is provided by this invention an apparatus and method of supplying to ignite a plasma wherein in the event of an arc a shunt switch is used to divert the power away from the plasma that is incorporated into an over-voltage protection circuit that controls the shunt switch to act as a boost switch when the arc is extinguished such that the stored inductor energy is used to boost the ignition voltage for reigniting the plasma if it is extinguished. When the arc is extinguished, the inductor current is diminished, and the plasma is ignited, then the switch S1 is turned OFF and the inductor energy goes to the plasma and the power supply operates in its normal operating mode.

An AC light emitting device is disclosed. The AC light emitting device includes at least four substrates. Serial arrays each of which has a plurality of light emitting cells connected in series are positioned on the substrates, respectively. Meanwhile, first connector means electrically connect the serial arrays formed on respective different substrates. At least two array groups each of which has at least two of the serial arrays connected in series by the first connector means are formed. The at least two array groups are connected in reverse parallel to operate. Accordingly, there is provided an AC light emitting device capable of being driven under an AC power source.

A method of controlling an output of an ultrasonic speaker that reproduces audible-frequency-band signal sounds by modulating carrier waves with audible-frequency-band signal waves output from a signal source and driving an ultrasonic transducer with the modulated waves includes: dividing the audible-frequency-band signal waves into a plurality of frequency bands; separately adjusting amplitudes of the signal waves and amplitudes of the modulated waves in the respective frequency bands; and driving a plurality of ultrasonic transducers provided corresponding to the respective frequency bands with the modulated waves generated corresponding to the respective frequency bands. Band-corresponding volume setting data, which is used to set volume of the ultrasonic transducers corresponding to the respective frequency bands by means of a plurality of band-corresponding volume setting units provided corresponding to the respective frequency bands, and overall volume setting data, which is used to set volume in common with respect to the plurality of ultrasonic transducers by means of an overall volume setting unit, are provided. Gains of modulated wave amplitude adjustment units that adjust the amplitudes of the modulated waves in the respective frequency bands are determined corresponding to the respective frequency bands on the basis of a combination of the band-corresponding volume setting data and the overall volume setting data.

Method for varying the power consumption of capacitive loads, in particular compact fluorescent lamps which are operated using a phase-gating dimmer by a converter (step-up converter). According to the invention, in the case of a nonconducting dimmer (i.e. no system power supply to the load), the switch (T1) in the converter (step-up converter) is closed. In the case of a conducting dimmer (i.e. when a system voltage is applied to the load), the step-up converter operation takes place until a predetermined maximum voltage is reached across the smoothing capacitor of the load.

The related over-voltage protector for high-power motor comprises: three ZnO arresters with cathode paralleled together and connected to ground terminal and anode connected to three-phase terminal, three groups of R-C devices with two ends connected to ground terminal and arrester another end respectively. This invention can reduce damage rate of high-power motor and transformer to 2%.

In the present invention, a current vector control unit, which separately controls a d-axis current and a q-axis current that are obtained from a current of an electric motor by means of orthogonal transformation according to a target command value, is provided, and a drive unit drives the electric motor. Furthermore, a phase angle command generation unit generates a phase angle command ([beta]*) on the basis of the difference ([increment]v*) between the absolute value (|v*|) of a voltage command from the current vector control unit to the drive unit and a predetermined reference value (Vlmt). A d-axis current command generation unit generates a d-axis current command (id*) on the basis of the sine value of the phase angle command ([beta]*). A q-axis current limiter sets a limit value for a q-axis current command (iq*) on the basis of the cosine value of the phase angle command ([beta]*). Due to this configuration, voltage saturation is eliminated, and the electric motor is highly stably driven while producing a high output even when a target command value in access of the possible output limit of the electric motor is input when the voltage is nearly saturated.

The invention relates to a charging device for a portable apparatus, which is applied to charging up a battery module of the portable apparatus. The charging device comprises a sensing circuit, a control unit and a linear charging circuit. The sensing circuit detects a sensing signal generated when a power converter is inserted into the portable apparatus and transmits the sensing signal to the control unit; the control unit generates a control signal according to the sensing signal and the electric quantity of the battery module. The charging device of the invention is characterized in that the linear charging circuit receives an output power supply of the sensing circuit and charges up the battery module according to the control signal.

A control apparatus for an electric vehicle includes a road surface condition detection portion, a slip determination portion, a torque reduction device, and a voltage control device. The electric vehicle includes a motor that generates drive power for the electric vehicle, and a drive device that drives the motor. The road surface condition detection portion detects the condition of a road surface on which the electric vehicle is driven. The slip determination portion determines whether the electric vehicle is slipping. The torque reduction device reduces the torque of the motor when the slip determination portion determines that the electric vehicle is slipping. The voltage control device controls a voltage input to the drive device to reduce the voltage when the road surface condition detection portion determines that the road surface has a friction coefficient lower than a predetermined value.

The present invention relates to a power factor correction circuit and a driving method thereof.

The power factor correction circuit receives an input voltage and maintains an output voltage at a constant level by controlling switching operation of a power switch connected to an inductor that supplies the output voltage. In this case, the power factor correction circuit controls switching operation of the power switch by differentiating a control structure for an output voltage respectively according to a stabilization period during which the output voltage is constantly maintained and a start-up period during which the output voltage is increased before being stabilized. In addition, the power factor correction circuit controls the switching operation of the power switch according to the control structure of the start-up period during a predetermined correction delay period from a time that the stabilization period starts.

Alternating current circuit breaker with a first galvanic separation switch (SW2) and a bypass switch (SW1) in a live line, and a second galvanic separation switch (SW3) in a neutral line, and a semiconductor switch element connected parallel to the bypass switch (SW1). The semiconductor switch element comprises a combination of a rectifier bridge (D1-D4) and an isolated gate bipolar transistor (IGBT). A processing unit is connected to a current measurement unit arranged in the live line, and is arranged to control the bypass switch (SW1), first and second galvanic separation switches (SW2, SW3) and the conducting state of the isolated gate bipolar transistor (IGBT) in case of detection of a short circuit condition.

The invention discloses a mixed type three-pole direct current power transmission system and a control method thereof. The system comprises a rectifying converter station and an inverting converter station, wherein the rectifying converter station and the inverting converter station respectively comprise an alternating current bus and a three-pole converting system, each alternating current bus is connected with a corresponding alternating current power grid, each three-pole converting system is hung on each alternating current bus through a converting transformer, and a converting unit H3 of each three-pole converting system adopts an MMC (modular multilevel converter). The system and the method have the advantages that the decoupling control capability of the active and inactive parts is realized, the power can be transmitted to an inactive network, the number of inactive compensation equipment is greatly reduced, the balance of the direct current among the three poles is maintained by introducing the MCC (modified current control), the current of a grounding pole is inhibited, the service life of the grounding pole is effectively prolonged, the on-site balance of the inactive power is realized by introducing the AVC (alternating voltage control), and the voltage of the connected AC (alternating current) system is maintained to solve the overvoltage or undervoltage problem.

The invention provides a power conversion device outputting the power generated by power source to the AC system and capable of improving the operation continuity of the AC system when the voltage decreasing. The power conversion device has an electric power converter (11) with one end connected to the AC system (2), the other end connected to the power source (3) for controlling the power generation of the generator; an electric power converter (10) for controlling the power outputted to the AC system; and a control portion (200) for controlling the electric power converter (10). An amplitude calculator (2001) calculates the voltage from the AC system, and executing current conversion to the voltage amplitude; an amplitude limiter (2005) limits the upper limit of power generated by the power source (3). A maximum power operation controller (20040 outputs the DC current and panel voltage and searches the current instruction value Idcref for executing maximum power operation. The current instruction value Idcref is limited between 0 to the upper limit, obtaining the different with IdcrefN DC current; the voltage instruction value Vchop is obtained by a current controller (2007) for outputting to the electric power converter (11).

The invention discloses a starting method for a flexible direct current transmission system. The flexible direct current transmission system comprises a two-end or multi-end voltage source transverter connected by aid of a direct-current circuit, a direct current side of the voltage source transverter is connected with an isolation knife switch, and an alternating current side is connected with a wire-inlet switch through a group of charging resistors and a bypass switch which are in parallel connection. The starting method comprises the following steps that the transverter is in electrode connection, the transverter is charged, a fixed direct current voltage control transverter reduces voltage and unlocks, direct current voltage is established; a non-direct-current voltage control transverter unlocks; and after unlocking is finished, direct current voltage instructions of the fixed direct current voltage control transverter enable voltage to be increased to a rated value according to set increasing and decreasing rate. The method can void overvoltage caused by controller overshooting in the unlocking process of the fixed direct current voltage control transverter, effectigvley supresses alternating current over-current generated during unlocking of the fixed direct current voltage control transverter, and effectively suppresses alternating and direct current overcurrent generated during the unlocking process of the non-fixed direct current voltage control transverter.

The invention discloses an open-circuit protection circuit, which comprises two branch load circuits of a constant-current driving circuit, a voltage stabilizing unit, an open-circuit detection unit and a short circuit unit. Two connection ends of the voltage stabilizing unit are connected with the two ends, with the same polarity, of the two branch load circuits; the other ends, with the same polarity, of the two branch load circuits have equal potential; the two ends, with the same polarity, of the two branch load circuits are also connected with two input ends of the open-circuit detectionunit respectively; and the output end of the open-circuit detection unit is connected with a control end of the short circuit unit. The open-circuit protection circuit has the advantages of low realization cost and wider application range.

A vehicle-mounted power generator set including: an AC generator driven by an engine of a vehicle; an electric power conversion portion that converts an output of the AC generator into an AC output having commercial frequency; a controller having electric power conversion portion control means for controlling the conversion portion to generate an AC output having commercial frequency when a control mode is a power generation mode, and engine control means for controlling the engine to rotate at a rotational speed suitable for supplying electric power from the conversion portion to a load when the control mode is the power generation mode and controlling the engine to be suitable for driving the vehicle when the control mode is the vehicle driving mode; and a control switch inserted between each output terminal of the AC generator and each input terminal of the electric power conversion portion, and controlled to be in an ON state when the control mode is the power generation mode and in an OFF state when the control mode is the vehicle driving mode.

The invention relates to a DC power grid line fault protection method. The method comprises steps: travelling wave signals at each measurement point are monitored in real time, if a protected set threshold is reached, a corresponding DC circuit breaker is tripped, all circuit breakers are finally tripped to realize separation of three DC subsystems, and the control mode of each subsystem converter station is switched. According to the travelling waves acquired at the measurement point, whether the fault is subsystem internal fault or subsystem external fault is judged by each subsystem through a fault positioning logic. If the subsystem external fault is judged according to the fault positioning logic, the line of the fault is determined according to the fault positioning logic, or otherwise, the subsystem internal fault is judged. According to an instruction of a dispatching system, the control mode of each converter station and a power control instruction are changed. The technical scheme of the invention can effectively shorten time needed for fault positioning, and power transfer brought by large-range DC power grid locking and influences on the stability of an AC and DC system can be reduced as much as possible. The phenomenon that the disclosed method is not applicable along with complexity of the DC power grid structure does not happen.

The invention relates to field of intelligent control, and specifically relates to a building intelligent lighting system comprising intelligent lamps, a wireless remote controller, a wireless gateway, a monitor, a server, and terminal devices. The wireless gateway is used to build a wireless lighting network and store electricity information of the intelligent lamps in the server. The server makes analysis of signals output by light sensors and on-off states of lamps in the intelligent lamps and other electricity information of the intelligent lamps to obtain an optimized electricity utilization scheme, and transmits a control command to the intelligent lamps through the monitor and the wireless gateway. Users can control the state of the intelligent lamps both through the wireless remote controller and the terminal devices, and can query the working state of the intelligent lamps by accessing a WEB page of the server through the terminal devices. Through intelligent control, the brightness, color, on-off and other information of the intelligent lamps can be adjusted, a green and energy-saving effect is achieved, and the ornamental value is improved. Moreover, the wireless network adopts a mixed structure, and is highly reliable.

The invention discloses an active clamping circuit driven by an IGBT. The active clamping circuit comprises a first transient voltage restraint diode, a second transient voltage restraint diode, a diode and a current-limiting resistor, the first transient voltage restraint diode, the second transient voltage restraint diode, the diode and the current-limiting resistor are sequentially connected between a collector and a grid of the IGBT, and a capacitor and a discharging resistor are connected to the second transient voltage restraint diode in parallel. Protection on a dynamic active clamp and a fixed active clamp of the IGBT is achieved. The active clamping circuit is simple in structure and high in universality, parameter setting of active clamping voltage can be carried out according to various application occasions, and the active clamping circuit can be applied to design of IGBT driving circuits under various working conditions.