504results about How to "Prevent overcurrent" patented technology

A square wave voltage having an amplitude equal to an output voltage of a converter is applied to an AC motor by a square wave control block. Torque control of the AC motor is performed basically by changing the voltage phase of the square wave voltage according to the torque deviation. When the motor revolution is suddenly changed, a instruction value correction unit sets a voltage instruction value of the output voltage of the converter according to a change ratio of the motor revolutions. This improves control of the motor current by changing the voltage applied to the motor in accordance with the sudden change of the motor revolutions without waiting for torque feedback control having a low control response.

A protector that protects a rectifier, and a wireless power receiver including the protector are provided. In one embodiment, a protector for an electronic device may include: a switch configured to control current flow to a rectifier of the electronic device; and a switch controller configured to: compare, with a predetermined threshold value, a voltage difference between an output voltage of the rectifier and a voltage of the electronic device; and transmit a control signal to the switch (i) to discontinue current flow to the rectifier when the voltage difference is greater than the predetermined threshold value, and (ii) to enable current flow to rectifier when the voltage difference is less than or equal to the predetermined threshold value.

A secondary battery includes an electrode assembly having a first electrode, a second electrode, and a separator located between the first electrode and the second electrode; a first collector plate electrically coupled to the first electrode, wherein the first collector plate has a first fuse hole and includes at least one first reinforcement protrusion having a first reinforcement groove and being spaced from the first fuse hole; a second collector plate electrically coupled to the second electrode; a case housing the electrode assembly, the first collector plate and the second collector plate, the case having an upper opening; and a cap assembly sealing the upper opening of the case.

A battery system includes a battery unit in which battery arms are connected in parallel, and a charge/discharge control device that controls charge/discharge of the battery unit. Each of the battery arms includes: a battery composed of one or more battery cells connected in series; a switch connected in series to the battery; and a battery monitoring device that, in a case of having detected abnormality of the battery, opens the switch to thereby isolate the battery arm including the abnormal battery, and sends a switch opening signal indicating that the switch has been opened to the charge/discharge control device. The charge/discharge control device performs a control to reduce a charge/discharge current or charge/discharge power of the battery unit when the switch opening signal is sent from the battery monitoring device of the battery unit to the charge/discharge control device.

An electrostatic chuck using the Johnson-Rahbek force, comprising: a dielectric material layer including a ceramics layer and a resin layer formed on the ceramics layer; and an electrode for generating an electrostatic adsorption power.

The invention discloses an active power filter device based on a coupled inductance, which is composed of a signal acquisition module, a main control module, a drive module, a power conversion module and an LCL filter module based on a coupled inductance. The steps of extracting command current are as follows: first, extract sinωt and cosωt which are synchronized with grid A-phase voltage ua through digital phase-locked loop; secondly, transform the three-phase grid current into dqo coordinates to obtain current id, iq in dqo coordinate system , io; the third is to perform digital low-pass filtering on id and iq to extract their DC components; the fourth is to inversely transform io, sinωt and cosωt to dqo coordinates; the fifth is to perform subtraction to obtain the three-phase grid current The fundamental reactive and harmonic currents in . After hysteresis comparison control, PWM gating signals and trigger pulses are generated to control the orderly on-off of each IGBT in the power conversion module to generate PWM voltage, which is filtered by the filter module and then injected into the grid for compensation.

The invention discloses a power battery pack detecting, evaluating and equalizing charge system and an applying method thereof. The power battery pack detecting, evaluating and equalizing charge system is characterized by comprising a battery pack detection part and an intelligent control part, wherein the battery pack detection part comprises a connector I and a plurality of voltage detection lines; the intelligent control part comprises a connector II, a plurality of voltage detecting and equalizing modules (1), a central controller, a current inducer (3), a control display panel (4), a load (5) and a charger (6); and the system is used for measuring voltage and temperature information of a power battery pack and measuring charge and discharge currents of the battery pack. The inventioncan be used for carrying out detecting, evaluating and equalizing charge on the power battery pack, helps a user know the current state of the power battery pack, improves the property of the power battery pack, and prolongs the service life.

The invention discloses an inverter protection circuit. The circuit is used for protecting a voltage source inverter in an inverter with direct current fault ride-through capability, wherein the inverter is composed of a diode valve group or a current source type valve group unit and a voltage source type valve group unit, and the diode valve group or the current source type valve group unit and the voltage source type valve group unit are connected in series. A bypass thyristor valve group is connected in parallel with both ends of the inverter with direct current fault ride-through capability. The anode and the cathode of the bypass thyristor valve group are connected with the positive pole and the negative pole of the inverter with direct current fault ride-through capability respectively. The invention further discloses an inverter protection method. When the voltage source inverter detects that an alternating current or direct current system is failed and the voltage or current ofthe voltage source inverter exceeds a threshold value, the bypass thyristor valve group is input, and fault information is transmitted to a rectifier station. The rectifier station reduces the directcurrent voltage and reduces the direct current to zero. The bypass thyristor valve group is turned off due to current zero-crossing. The voltage source inverter protection circuit effectively solvesovervoltage and overcurrent problems caused by direct current charging of the voltage source inverter, and ensures the reliable operation of the voltage source inverter.

A power supply unit, a distributed power supply system and an electric vehicle loaded therewith, capable of charge/discharge operation are disclosed. A first cell group is connected in parallel to a second cell group in which the electrolytic solution can be electrolyzed or the generated gas can be recombined. A plurality of the parallel circuit pairs are connected in series, and the series circuit is connected with a charger/discharger to constitute the power supply unit. The charger/discharger charges the power supply unit up to a voltage at which the electrolytic solution of the second cell group is electrolyzed or the generated gas is recombined.

The invention discloses a low voltage ride-through control method of a doubly fed induction aero-generator, which is used when a power network has short circuit faults. The control method is characterized in that a rotor exciting voltage positive-sequence control current and a rotor exciting voltage negative-sequence control signal are respectively formed through limiting a rotor slip frequency current and a rotor (2-s) rated frequency current when the power network has faults, and a generator is utilized for realizing the attenuation of stator flux transient DC components and reducing the rotor side influences of the stator flux transient components, positive-sequence components and negative-sequence components. The control method has the advantages that no hardware protecting device is required to be added; under the condition that the power network has symmetrical and asymmetrical faults, the overcurrent occurrence of the rotor can be effectively restrained, and the safe operations of the generator and a rotor exciting converter are protected; in the process that the power network has the faults, the transient generator impact to the power network and a mechanical system can be effectively reduced; the normal operation of the generator can be fast recovered after the faults are removed, and the timely support to the power network can be realized.

A power switching circuit according to an exemplary embodiment of the present invention includes an output transistor connected between a power supply terminal VCC and an output terminal OUT, an output controller which controls a conducting state of the output transistor according to an input signal, a sense transistor having a gate commonly connected with the output transistor, which detects an output current flowing into the output transistor, an output current detection terminal in which a detection voltage is generated according to the output current detected by the sense transistor and a short circuit detector which detects a short circuit condition of the output current detection terminal according to the detection voltage and stops the output transistor or limits the output current.

The invention relates to the field of electric vehicle connectors, and in particular relates to a novel electric vehicle connector plug with a convertible contact pin. The electric vehicle connector plug comprises a power supply plug and a changeover plug, wherein the power supply plug is provided with a power supply contact pin, the power supply contact pin is connected with a power supply cable; the changeover plug is detachably connected with the power supply plug, and the changeover plug is provided with a jack connected with the power supply contact pin, and a connecting contact pin electrically connected with the jack, and the connecting contact pin is used for inserting in the plug. The electric vehicle connector plug further comprises a current detector electrically connected with the changeover plug, a temperature detector electrically connected with the changeover plug, wherein the the current detector is a current detection resistor and can be used for detecting the current system of the access current; and the temperature detector is a thermosensitive resistor and can be used for detecting the temperature of the changeover plug. The electric vehicle connector plug has the beneficial effects that the changeover plug is added to detachably connect with the power supply plug, a user can select the appropriate changeover plug according to the local power utilization system, thereby improving the applicability of the charging connector.

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 discloses an intelligent electric phase separation device of an alternating current electrified railway. The intelligent electric phase separation device is composed of a first switch, an impedor connected with the first switch in parallel, a second switch, an impedor connected with the second switch in parallel, a sensor for detecting the current and voltage of the first switch, a sensor for detecting the current and voltage of the second switch and the like, wherein the first switch is connected with a first electric supply arm and a phase separation area, and the second switch is connected with a second electric supply arm and the phase separation area. According to the device, the train pantograph position can be automatically recognized through the voltage information at the two ends of the first and second switches and the current information flowing through the first and second switches, and the first and second switches are automatically turned on or off according to the recognized pantograph position, so that the phase separation area obtains or cuts off electric energy of the electric supply arms. The circuit structures of the switches and the impedors connected with the switches parallel can be replaced with the circuit structures of linked switches at the two ends of a step-down transformer and a low-voltage winding thereof. According to the device, no train position detection mechanism needs to be installed on a track, the structure is simple, and use and maintenance are convenient.

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.

The invention belongs to the field of controlling a power conversion device of a wind driven generator, relating to a rotor current control method of a double-fed wind driven generator under power grid faults. The method comprises the following steps: obtaining the stator voltage and the rotor current under a two-phase static coordinates by utilizing the detected three-phase stator voltage and the three-phase rotor current through a 3/2 conversion module; calculating the stator magnetic flux linkage and the position angle; calculating the slip frequency angle and the slip frequency angular velocity; summating the stator magnetic flux linkage position angle and the rotor position angle, and then carrying out differentiation to obtain the sum of the magnetic flux linkage angular velocity and the rotor angular velocity; calculating the rotor current set values under the two-phase static coordinates of a rotor; respectively subtracting the rotor current set values under the two-phase static coordinates of the rotor with the rotor current under the two-phase static coordinates and obtaining the reference value of the rotor voltage under the two-phase static coordinates through the calculation by utilizing a performance requirement (PR) controller; and generating the switching signal of a control power device. The rotor current control method has the advantages that the rotor current oscillation of a double-fed induction generator (DFIG) resulted from power grid faults can be effectively inhibited, the grid in-service operation of the double-fed wind driven generator, and the operation performance of the DFIG under the power grid faults is enhanced.

The invention discloses a control strategy of a multi-circuit MMC (modular multilevel converter)-HVDC (high voltage direct-current ) fed extremely-weak grid. The control strategy includes that 1), a synchronous generator simulation control method is adopted to all the MMCs, an active-frequency loop is used for simulating the swinging process of a synchronous generator, an idle-voltage loop is used for simulating an excitation system of the synchronous generator, and failure current is limited and MMC response speed is increased by adopting an inner current loop; 2), a dynamic power distribution control method is adopted to power distribution among the MMCs, a preset power reference value is not used any longer, and the power reference value is dynamically adjusted according to specific proportion according to changes of system load. By the arrangement, the MMC-HVDC fed extremely-weak grid is enabled to run stably, power distribution can be rapidly and effectively performed, frequency deviation caused by power fluctuation to the system is removed, the MMCs can have inertia effect as the synchronous generator, and high reference meaning and use value in engineering are achieved.

The invention discloses a non-flux observation doubly-fed induction generator low voltage ride-through control method and a system, which can be applied to excitation control on a rotor-side converter of the doubly-fed induction generator in the case of deep power grid fault. The specific implementation method comprises steps: once deep fault is detected to happen to the power grid, rotor current of the doubly-fed induction generator is instantly controlled to directly track stator current at a certain ratio, and a certain compensation term related to stator voltage is injected to a rotor current instruction for providing dynamic reactive support. The invention also provides a control system structure diagram for realizing the above principle. Compared with de-excitation control, flux tracking and other low voltage ride-through excitation control methods, no flux observation step is needed for generating a transient control instruction, the structure is simple, multiple control objectives such as electromagnetic torque ripple suppression or dynamic reactive power compensation can be realized, and the low voltage ride-through ability of the doubly-fed induction generator is greatly enhanced.

A source drive circuit which drives a source line group (source lines) of a liquid crystal display, includes a source driver group (source drivers) which outputs drive signals, an analog switch group which connects the outputs of the source driver group to the source line group and disconnects the same from the source line group, an analog switch group which shortcuts the source line group to a common power supply and disconnects the same from the common power supply, and a switch control circuit which controls switch operations of both the analog switch groups. The switch control circuit turns ON the analog switch group after it has detected that all analog switches of the analog switch group have been turned OFF, and turns ON the analog switch group B after it has detected that all analog switches of the analog switch group have been turned OFF.

An intermediate metal film is formed between a Schottky electrode and a pad electrode. A Schottky barrier height between the intermediate metal film and a silicon carbide epitaxial film is equivalent to or higher than a Schottky barrier height between the Schottky electrode and the silicon carbide epitaxial film. By this configuration, an excess current and a leak current through a pin-hole can be suppressed even in the case in which a Schottky barrier height between the pad electrode and the silicon carbide epitaxial film is less than the Schottky barrier height between the Schottky electrode and the silicon carbide epitaxial film.

The invention discloses a low-voltage crossing method of two-stage type photovoltaic grid connected system of variable power tracking path, which belongs to the field of new energy electric power system and micro power grid technology. Under the prerequisite that the original configuration of a two-stage three phase photovoltaic grid connected system is not changed and no auxiliary device is added, the power tracking path can be adjusted through the feed-forward control of the falling amplitude of voltage, the voltage at the photovoltaic cell end can be changed in a real-time manner, and the output of the photovoltaic cell power can be rapidly and effectively controlled, and the balance of power at two sides of an inverter can be realized. Through the cooperative control with a grid connected inverter, it can be guaranteed that under the prerequisite that the grid connected output of current of the inverter is not out of limit, active power and reactive power can be provided for the power grid as more as possible, the recovery of power grid voltage can be supported to the most extent, and the zero-voltage crossing of the photovoltaic grid connected system can be realized. Comparedwith the conventional control method, the invention is advantageous in that no additional device is required; safe and stable running of the system can be realized; the cost of the photovoltaic powergeneration system can be reduced, and practicality is better.