172 results about "Voltage polarity" patented technology

A method and apparatus for the electrochemical polishing of metallic workpieces are proposed, wherein an electrolyte medium containing solid granular particles and a liquid electrolyte is placed in a container and conductively connected to a first electrode, wherein the metallic workpiece is conductively connected to a second electrode and immersed in the electrolyte medium in the container, wherein the electrodes are subjected to an electrical voltage such that the first electrode in contact with the electrolyte medium has a negative voltage and the second electrode in contact with the workpiece has a positive voltage, and wherein the workpiece is moved relative to the majority of solid granular particles of the electrolyte medium in order to polish it electrochemically.The invention provides that the polarity of the electrical voltage applied to the electrodes is temporarily reversed at least once, in particular periodically, during the electrochemical polishing of the workpiece, so that the first electrode in contact with the electrolyte medium temporarily has a positive voltage and the second electrode in contact with the workpiece temporarily has a negative voltage.

A busbar for a computing rack is disclosed. The busbar comprises a pair of electrically conductive rails each having a first end and a second end. The pair of rails are configured to provide opposite voltage polarities to devices mounted in the computing rack. The open channels are enclosed within each of the rails and extend from the first end to the second end in each respective rail. An expansion valve is coupled to the open channels at the first end and is configured to expand air passed from a compressed-air source into the at least one open channel while the pair of rails are attached to an electrical power source. An input end cap is attached to the first end of at least one of the rails. The input end cap provides a manifold for routing air from the expansion value into the at least one open channel.

The invention relates to the technical field of flexible direct-current power transmission, and discloses a direct-current power stabilizing device of an MMC bridge arm cascade dual-port switching type energy storage module. Two ends of an upper bridge arm and a lower bridge arm of the MMC are respectively connected with a dual-port switching type energy storage module in series, and the MMC is connected with a positive electrode and a negative electrode of a direct current bus through the dual-port switching type energy storage modules. The dual-port switching type energy storage module comprises a bipolar DC / DC converter, the bipolar DC / DC converter is provided with two output ports, the voltage polarity (positive voltage or negative voltage) of the output ports can be switched according to the surplus or vacancy condition of the direct current side power, rapid charging and discharging control of the energy storage module is achieved, and therefore the direct current side power fluctuation is effectively stabilized, and the stability of the voltages at the two ends of the MMC is maintained. According to the invention, the stability is improved and the power is stabilized while the work of the MMC is not influenced, and the switching loss and the cost are effectively reduced.

The invention relates to the technical field of flexible direct current power transmission, in particular to a reconfigurable bipolar switchable energy storage system and a control method thereof, and the system comprises an energy storage unit which comprises a battery; the input end of the energy conversion unit is connected to the energy storage unit, and the energy conversion unit is used for converting the stored energy into bidirectional direct-current electric energy; the input end of the polarity switching unit is connected to the output end of the energy conversion unit, and the polarity switching unit is used for switching the voltage polarity of the output port; and the control unit is used for respectively sending driving signals to the energy conversion unit and the polarity switching unit. According to the invention, the problem that the switching between the positive voltage output and the negative voltage output is completed according to the surplus or vacancy condition of the direct current side power in the large-scale renewable energy access power grid is effectively solved, and the rapid charging and discharging control of the energy storage system is realized, so that the direct current side power fluctuation is effectively stabilized, and the stability of the voltages at the two ends of the MMC is rapidly maintained.

The invention provides a DC-DC forward boost-buck power conversion circuit based on cascaded Cuk topologies, and relates to the technical field of power electronic conversion, the circuit is mainly formed by cascading two Cuk topologies sharing one inductor, and the circuit also comprises a power supply end, a load end and a same-frequency driving signal generator. The same-frequency driving signal generator controls the two power switch tubes in the Cuk topology through a same-frequency signal, and the output voltage is adjusted by adjusting the duty ratio. The circuit not only keeps the advantage of continuous input and output current of a traditional Cuk circuit, but also converts the polarity of the output voltage from the reverse direction to the forward direction, and meanwhile, the voltage gain is remarkably improved, so that forward voltage conversion can be efficiently and smoothly realized. The circuit structure has the characteristics of high gain, forward output, continuous current, simple control and the like, and is suitable for occasions requiring high-efficiency and high-quality electric energy conversion, such as new energy power generation and energy storage, electric automobiles, precision industry and the like.

The invention discloses a fault detection method for a flexible DC power transmission system and a related device, and the method employs a voltage gradient algorithm to detect whether the flexible DC power transmission system breaks down, and carries out the fault type discrimination based on the ground model voltage polarity through a sampled voltage signal when the system breaks down. And determining a high-frequency impedance difference value ratio of a rectification side and an inversion side in the flexible DC power transmission system based on the voltage signal and the sampled current signal, carrying out fault direction discrimination based on the high-frequency impedance difference value ratio, and finally determining a fault detection result according to a fault type and a fault direction. Therefore, the fault pole selection is realized based on the ground model voltage polarity, and the internal and external faults are accurately distinguished through the high-frequency impedance difference ratio, so that the reliability of fault detection of the flexible direct-current power transmission system is improved.

The invention discloses an electrical quantity polarity and phase sequence adaptive correction method and system, and belongs to the technical field of power system relay protection, and the method comprises local voltage and current polarity correction, local voltage and current phase sequence correction, two-side voltage polarity consistency correction, two-side voltage phase sequence consistency correction, and local voltage-current phase sequence correction. The polarity of current on two sides is corrected, and the polarity and phase sequence of voltage and current on two sides of the local and the section are automatically adjusted through a multi-stage dynamic detection and correction process, so that the problem of maloperation or refusal operation of pilot protection and directional protection caused by primary and secondary wiring abnormity in the medium-voltage power distribution network is solved; accuracy and consistency of input data of pilot protection and direction protection algorithms are ensured, and reliability and adaptability of a protection device are remarkably improved.

The invention relates to a differential voltage time-digital converter for preventing large based on Double-tailed, and the differential voltage time-digital converter comprises a Double-tailed dynamic latch comparator which carries out the linear amplification of an input differential voltage, and outputs a differential voltage; a voltage time domain converter (VTC) which converts the output differential voltage into a time difference signal and outputs a first delay voltage and a second delay voltage; the input end of the polarity judging device is connected with the VTC, and the polarity judging device is used for outputting a polar code as the highest bit of a thermometer code; the input end of the edge selector ELS is connected with the VTC, and the edge selector ELS is used for generating an EARLY signal and a LATE signal according to the first delay voltage and the second delay voltage; and the input end of the delay chain type time-to-digital domain converter TDC is connected with the edge selector ELS, and the delay chain type time-to-digital domain converter TDC is used for quantizing the time difference between the EARLY signal and the LATE signal and generating a thermometer code. According to the invention, the idea of high-speed latch is introduced to obtain stable differential input voltage with smooth waveform, so that the VTC module can carry out time domain transformation on the differential input voltage, and the resolution of the TDC is improved.

The invention relates to the technical field of off-grid and grid connection, and provides a closed-loop control strategy and circuit based on threshold criterion and dual-mode switching. Different control modes are triggered according to the change of the voltage difference by monitoring the voltage difference delta V of the positive and negative bus capacitors in real time. When the capacitor voltage difference delta V is lower than a preset threshold value, the system enters a standby mode, and additional adjustment is not needed; and when the voltage difference delta V is greater than or equal to a threshold value, dynamic compensation is triggered and next-step control is entered. The system judges through voltage polarity, and if a positive bus overvoltage working condition is detected, a BUCK step-down mode is started; and if the working condition is the negative bus overvoltage working condition, starting a BOOST mode. In order to ensure independence and stability of a voltage regulation process, an independent decoupling circuit is adopted to isolate an energy transfer process from a main inverter path in a BUCK or BOOST mode. Based on the real-time feedback closed-loop control of the capacitor voltage difference delta V, the switch duty ratio is dynamically adjusted, the dynamic response capability and stability of the system are effectively improved, the overvoltage risk is reduced, and the electric energy regulation and control efficiency is optimized.

The application discloses a multi-voltage liquid crystal gate driving system, which comprises a power module, a pixel voltage modulation module, a common voltage modulation module and a voltage output module. The power module is used for outputting a power voltage. The pixel voltage modulation module is used for modulating a pixel voltage required by multi-voltage liquid crystal gate driving. The common voltage modulation module is used for modulating a common voltage required by multi-voltage liquid crystal gate driving. The voltage output module is electrically connected to the common voltage modulation module to output a voltage to be modulated to the common voltage modulation module. The voltage switching module is electrically connected to the power module and the voltage output module respectively, so that the voltage switching module can output a plurality of switching voltages coupled with the power voltage to the voltage output module. The application has the beneficial effect of providing a multi-voltage liquid crystal gate driving system based on switching different resistances and voltage polarity reversal to output a plurality of common voltages and pixel voltages to modulate a plurality of gray scale voltages.

The invention relates to the field of power electronic converters and control, in particular to an SOP power module dead-zone effect suppression method, which comprises the following steps: acquiring the current transmission power of an SOP power module; based on the transmission power, generating a first bus voltage instruction used for controlling an AC-DC side direct current bus voltage and a second bus voltage instruction used for controlling a DC-AC side direct current bus voltage, adjusting the corresponding direct current bus voltage so as to inhibit polarity reversal of a DAB converter bridge port voltage, and according to the transmission power of the SOP power module, adjusting the polarity of the DAB converter bridge port voltage. A first bus voltage instruction and a second bus voltage instruction are generated, the first bus voltage instruction and the second bus voltage instruction are made to be unequal during light load, a bus voltage difference value is formed, and it is ensured that the direct-current bus voltages on the two sides meet the condition for restraining DAB bridge port voltage polarity reversal in the dead-zone time period by means of compensation for frequency doubling fluctuation components in the direct-current bus voltages. Current zero step is eliminated, soft switching is recovered, voltage stability under light load is improved, extra hardware or complex control is not needed, and engineering realization is simple and convenient.

To provide a semiconductor memory device with superior characteristics. [Solution] The semiconductor memory device of the embodiment includes a memory cell including a semiconductor layer, a gate electrode layer containing a ferroelectric material, and first and second wiring connected to the semiconductor layer, and a control circuit. The control circuit is capable of performing a first write operation, which involves applying a first voltage of first polarity to the memory cell, and a second write operation, which involves applying a second voltage to the memory cell that has an absolute value smaller than the first voltage of first polarity. The control circuit is capable of performing a first operation on the memory cell before the second write operation on the memory cell. The first operation involves applying a voltage to the memory cell that has an absolute value larger than the second voltage of first polarity, and applying a voltage with the opposite polarity to the first voltage that has an absolute value larger than the second voltage.

A display driving circuit and a display driving method are provided. The display driving circuit includes a controller, a common voltage supply circuit, and a border voltage supply circuit. The controller generates a plurality of border voltage control signals and a plurality of common voltage control signals. The common voltage supply circuit outputs a common voltage to the display panel according to the plurality of common voltage control signals. The border voltage supply circuit outputs a border voltage to the display panel according to the plurality of border voltage control signals. When a voltage polarity of the common voltage is reversed, the common voltage supply circuit performs charge sharing by a common ground voltage.

The application discloses a motor control method, device, equipment and storage medium, the method comprises: obtaining the first phase of the voltage instruction at the current sampling point; determining the second phase of the voltage instruction at the next sampling point; determining that the first voltage polarity and the second voltage polarity are different based on the first phase and the second phase, and determining the zero point phase; determining the duty cycle of the inverter switch signal based on the first phase, the second phase and the zero point phase; and controlling the opening and closing of the inverter switch based on the duty cycle of the switch signal. In this way, by predicting the second phase of the voltage instruction at the next sampling point according to the first phase of the voltage instruction at the current sampling point, determining the zero point phase, and then determining the duty cycle of the inverter switch signal, when the switch is controlled based on the duty cycle, the switch state can be changed in time when the voltage instruction passes through the zero point position, the low-frequency harmonic of the alternating current motor phase current is reduced, and the motor loss is reduced.

Current sensor arrangement for measuring an effective primary current (i P ) in a primary conductor (1); the current sensor arrangement comprises the following: a magnetic core (10) for magnetically coupling the primary conductor (1) to a secondary conductor (2); a controlled voltage source (Q) connected to the secondary conductor (2) and designed to apply a voltage (±Us) with adjustable polarity to the secondary conductor (2) so that a secondary current (i S ) flows through the secondary conductor (2); a measuring and control unit (20) coupled to the secondary conductor (2) and designed to generate a measuring signal (u SH ), continuously detecting the reaching of magnetic saturation in the magnetic core (10) and, upon detection of magnetic saturation of the magnetic core (10), reversing the voltage (±Us) in order to remagnetize the magnetic core (10), wherein the measuring and control unit (20) is further designed to evaluate a spectrum of the measuring signal and, depending thereon, to determine a frequency of a current flowing through the primary conductor.

Methods, systems, and devices for switch and hold biasing for memory cell imprint recovery are described. A memory device may be configured to perform an imprint recovery procedure that includes applying one or more recovery pulses to memory cells, where each recovery pulse is associated with a voltage polarity and includes a first portion with a first voltage magnitude and a second portion with a second voltage magnitude that is lower than the first voltage magnitude. In some examples, the first voltage magnitude may correspond to a voltage that imposes a saturation polarization on a memory cell (e.g., on a ferroelectric capacitor, a polarization corresponding to the associated voltage polarity) and the second voltage magnitude may correspond to a voltage magnitude that is high enough to maintain the saturation polarization (e.g., to prevent a reduction of polarization) of the memory cell.

The present application relates to an electric-motor control system for a movable furniture unit. The electric-motor control system comprises an electric motor, a power source, a manually controlled switch and a pinch protection execution switch, wherein the pinch protection execution switch may be switched between a first execution position and a second execution position; at the first execution position, the electric motor is connected to the manually controlled switch by means of the pinch protection execution switch, and the polarity of a voltage that the power source applies to the electric motor is changed by means of switching the manually controlled switch; and at the second execution position, the electric motor is connected to the power source by means of the pinch protection execution switch, and the electric motor rotates and drives the furniture unit to extend so as to realize pinch protection. The present invention further relates to a pinch protection apparatus and a pinch protection system for a movable furniture unit, and the movable furniture unit.

In order to provide a charged particle beam device capable of returning to a usable state in a short time after completion of flushing processing for continuously and stably using an electron beam having a high luminance and a low energy dispersion and capable of shortening the downtime of the device, the charged particle beam device is configured as follows.　The charged particle beam device comprises: an electron source that emits electrons; an extraction electrode that faces the electron source and generates an electric field for causing the electron source to emit electrons; a first voltage power supply that applies a first voltage to the electron source in order to emit electrons from the electron source; a second voltage power supply that applies a second voltage to the extraction electrode; and a cooling device that cools the electron source. The charged particle beam device further comprises: a third voltage power supply that, in order to remove gas molecules adsorbed onto the electron source in the process of a specimen inspection, applies a third voltage having a polarity opposite to that of the first voltage to the electron source and thereby can set an electric field generated between the electron source and the extraction electrode such that the electron source is positive and the extraction electrode is negative; and a control unit for performing control so as to stop applying the first voltage from the first voltage power supply when applying the third voltage from the third voltage power supply to the electron source.

The invention discloses a high-voltage cable buffer layer damping defect discharge state evaluation method and system, and belongs to the technical field of high-voltage cable partial discharge detection. According to the high-voltage cable buffer layer damping defect discharge state evaluation method provided by the invention, test parameters are preset through an adjustable square wave voltage generator, and in an output end voltage adjustment stage, the output end voltage intensity is gradually increased at a first preset step length; when the voltage of the output end reaches a first preset peak value and partial discharge is still not triggered, the rising edge slope of the polarity overturning stage is adjusted, the rising edge slope of the polarity overturning stage is increased through a second preset step length, and the rising edge slope of the square wave voltage polarity conversion stage is enhanced to excite the potential partial discharge defect; not only can the requirements on the on-site power supply capacity and the volume of a test device be reduced, but also the high-voltage cable cannot be damaged, and meanwhile, the damping defect discharge of the buffer layer composite material can be effectively excited.

The invention provides a display panel and a display device, the display panel comprises a substrate, data signal lines, touch control wires and touch control electrodes, the data signal lines are arranged on one side of the substrate, the data signal lines extend in the first direction, and the multiple data signal lines comprise first signal lines and second signal lines. The touch wires are arranged on one side of the substrate and extend in the first direction. The touch control electrodes are arranged on the side, away from the substrate, of the touch control wire, the multiple touch control electrodes are arranged at intervals in the first direction, and the touch control wire is electrically connected to the touch control electrodes. Wherein the orthographic projection, on the substrate, of the touch wire electrically connected with the single touch electrode is overlapped relative to the orthographic projection, on the substrate, of the first signal line and the orthographic projection, on the substrate, of the second signal line or is adjacently arranged in the second direction, and the voltage polarities, relative to the touch electrodes, of the first signal line and the second signal line are opposite; the first direction and the second direction intersect and are parallel to the plane where the substrate is located.

The invention discloses an electronic product surface static electricity detection circuit and method. The static electricity detection circuit comprises a static electricity collection module, a signal conditioning module, a polarity judgment module and an indication module. The electrostatic collection module is used for collecting electrostatic signals on the surface of the electronic product and outputting the electrostatic signals to the signal conditioning module; the signal conditioning module is used for performing impedance matching, amplification and filtering processing on the electrostatic signal to obtain a conditioned detection signal; the polarity judgment module is used for judging positive and negative attributes of static electricity according to the voltage polarity of the conditioned detection signal; the indication module is used for indicating the polarity and the intensity grade of the static electricity according to the output result of the polarity judgment module; through the modular circuit design, rapid and portable detection of static electricity on the surface of an electronic product is achieved, the positive polarity and the negative polarity of the static electricity can be effectively distinguished, and the problems that in the prior art, detection equipment is heavy and single in function, and the polarity cannot be recognized are solved.

The invention relates to the technical field of converter modulation, in particular to a three-level converter modulation method of an ANPC-2 type hybrid power module, which comprises the following steps: S1, four-quadrant operation control of a converter: defining four working states according to the combination of output voltage polarity and output current direction, distributing a steady-state switching sequence of the power tube for each state; s2, starting and stopping control of the converter: switching on / off a power tube step by step according to a preset time sequence based on the target working state; and S3, commutation control of the converter: when four-quadrant operation needs to switch the voltage polarity, when the modulation method is used, all working states of the ANPC-2 type three-level topological converter in the modulation method are analyzed, power frequency outer tubes VT1 and VT4 and power frequency clamping tubes VT5 and VT6 are all turned off in a zero-voltage or zero-current state and do not bear extra stress voltage, so that the power frequency outer tubes VT1 and VT4 and the power frequency clamping tubes VT5 and VT6 are turned off in a zero-voltage or zero-current state and do not bear extra stress voltage, and therefore, the power frequency outer tubes VT1 and VT4 and the power frequency clamping tubes VT5 and VT6 are turned off in a zero-voltage or zero-current state. And the power frequency tube can select a silicon-based IGBT with relatively low withstand voltage, so that the cost is reduced, and the marketization application of the hybrid power module is realized.

Methods and apparatus are disclosed for providing welding power. An example welding-type power supply includes a transformer having a first secondary winding and a second secondary winding, a switching element configured to control current flow from the first secondary winding and the second secondary winding to an output, and a control circuit configured to control the switching element to selectively output a positive output voltage and a negative output voltage without a separate rectifier stage by selecting a first subset of the switching elements to perform rectification based on an output voltage polarity.

The utility model provides a voltage polarity switching device and a transistor testing system, and relates to the technical field of semiconductor testing. According to the invention, the voltage input ends of the plurality of polarity switching units are externally connected with a single-polarity power supply of the programmable power supply, and the voltage reference ends of the plurality of polarity switching units are grounded at the same time, and then the main control unit is electrically connected with the plurality of polarity switching units. The plurality of polarity switching units are controlled to carry out power supply positive and negative voltage polarity switching on an external unipolar power supply, so that the plurality of polarity switching units are ensured to provide test voltages with adjustable voltage polarity to the transistor to be tested through the voltage output ends. Therefore, the automatic positive and negative voltage polarity switching function of the multi-path unipolar power supply in the programmable power supply is realized at low cost, the manual participation degree in the transistor testing process is reduced, the required direct current voltage polarity can be quickly and accurately adjusted based on the programmable power supply, and the transistor testing efficiency is effectively improved.

A dispensing apparatus includes a stage on which a substrate is seated, a dispensing head positioned above the stage, including a head electrode to which a first voltage is applied to electrically charge a resin, and configured to discharge the charged resin through a nozzle onto the substrate in the form of dots, and a resin control electrode positioned between the dispensing head and the stage, where a second voltage having a same polarity as the first voltage is applied to the resin control electrode to control a position of the resin dot discharged from the nozzle.

The application provides an alternating voltage electric spray thruster working state recognition method, device and equipment, relates to the electric spray thruster technical field, and comprises the following steps: in the case where the voltage polarity of an alternating voltage electric spray thruster reverses, collecting a corresponding emission current sequence of the alternating voltage electric spray thruster; extracting a target characteristic quantity corresponding to the emission current sequence, the target characteristic quantity being used for describing the characteristics in the process in which the emission current sequence recovers from a disturbance state to a stable state after the voltage polarity reversal event occurs; and identifying the working state of the alternating voltage electric spray thruster according to the target characteristic quantity. The application can only use the emission current data of the thruster, extract a limited number of simple features from the current waveform under the alternating voltage condition, and realize online identification of states such as 'normal working / serious over spray / high and low flow / launching attenuation'.

An alternating current / direct current (AC / DC) power converter including a bridgeless power factor correction (PFC) circuit and a controller is provided. The bridgeless PFC circuit includes input-side wirings, output-side wirings, an input-side capacitor, a reactor, and a pair of switching elements disposed between the input-side wirings and the output-side wirings, and on which a switching operation is performed by the controller. The controller includes a peak current control unit which executes a peak current mode control by using a first slope compensation circuit corresponding to a positive polarity of AC input voltage, and a second slope compensation circuit corresponding to a negative polarity of the AC input voltage. The second slope compensation circuit has an inverting circuit which inverts the polarity of the AC input voltage, and is structured using a same slope compensation circuit as the first slope compensation circuit.

To provide a power conversion system with voltage step change and voltage polarity conversion functions.SOLUTION: A power conversion system includes a three-phase AC-DC conversion circuit that receives a three-phase power source and converts the three-phase power source into a DC power source, a plurality of DC-DC conversion circuits that receive a DC power source and convert the DC power source to generate a DC voltage, a first voltage, and a second voltage, respectively, a voltage step change circuit that receives the DC voltage, the first voltage, and the second voltage and adds the first voltage to the DC voltage or subtracts the second voltage from the DC voltage to supply a step-change DC voltage, and a voltage polarity conversion circuit that receives the step-change DC voltage and converts the polarity of the step-change DC voltage to supply a DC output voltage.SELECTED DRAWING: Figure 1

The application discloses a kind of high-voltage cable buffer layer damp defect discharge state evaluation method and system, belong to high-voltage cable partial discharge detection technical field.The high-voltage cable buffer layer damp defect discharge state evaluation method provided by the application, test parameters are preset by adjustable square wave voltage generator, in output voltage regulation stage, gradually increase output voltage intensity with first preset step size;When output voltage reaches first preset peak value and still does not trigger partial discharge, change to the rising edge slope of polarity reversal stage, improve the rising edge slope of polarity reversal stage by second preset step size, enhance the rising edge slope of square wave voltage polarity conversion stage to stimulate latent partial discharge defect;Not only can reduce the volume requirement of on-site power supply capacity and test device, and will not cause damage to high-voltage cable, while effectively stimulating buffer layer composite material damp defect discharge.

To achieve stable temperature control of a piezoelectric vibrator in a sensing device that detects a substance to be detected, under relatively low temperature conditions. [Solution] The sensing device of the present invention comprises a piezoelectric vibrator, an oscillation circuit for causing the piezoelectric vibrator to oscillate, a Peltier element for changing the temperature of the piezoelectric vibrator, a case for housing the piezoelectric vibrator, the oscillation circuit, and the Peltier element, a temperature sensor provided attached to the case for detecting the ambient temperature, and a selection unit for selecting one of the following: a first state in which the polarity of the voltage applied to the Peltier element can be changed so that heating and cooling of the piezoelectric vibrator are possible, and a second state in which the polarity of the voltage applied to the Peltier element is fixed so that only heating of the piezoelectric vibrator is possible.