367 results about "Chopper" patented technology

The invention discloses a fault ride-through test method for an offshore wind power flexible direct output system, and the method comprises the steps: building a fault equivalent circuit of the offshore wind power flexible direct output system, analyzing the operation characteristics of an AC power grid side under a low-voltage fault, and determining the incidence relation between the DC side excess energy and the power grid voltage drop; establishing a model representing each component in the fault equivalent circuit, wherein the components at least comprise a machine-side converter, a grid-side converter, a direct-current capacitor and an unloading resistor; when a low-voltage fault of an alternating-current power grid side is detected, executing the following cooperative control based on the model: synchronously starting unloading resistance control and reactive power support control, wherein an unloading resistor dissipates excess energy of a direct-current side through a direct-current chopper; the grid-side converter injects a capacitive reactive current which is deeply matched with the voltage drop of the power grid so as to improve the voltage of a grid-connected point; and if the direct-current voltage continuously exceeds the preset threshold value, starting power prompt drop control, and reducing the output power of the unit according to a gradient until the system recovers to be stable.

The present application provides a converter and a chopper transistor blocking control method therefor. According to the chopper transistor blocking control method, when switching transistors in a converter need to be blocked, switching transistors in a primary side circuit connected to a transformer of the converter are blocked, and switching transistors in a secondary side circuit are blocked when the current on a branch where a secondary side winding in the transformer is located is zero, or batch blocking of the switching transistors in the secondary side circuit is completed after the current on the branch where the secondary side winding is located recirculates to zero, thereby avoiding overvoltage damage to the switching transistors caused by the current on the branch where the secondary side winding is located recirculating by means of the junction capacitance of the switching transistors in the secondary side circuit.

A system for evaluating a sample, the system includes (i) a chopper that includes (i.1) a disc that is made of a transparent material that bears an inner opaque pattern and outer opaque pattern, the outer opaque pattern surrounds the inner opaque pattern, and (i.2) a rotating unit that is configured to rotate the disc during a modulation period, (ii) first optics, (iii) second optics, (iv) a control unit that is configured to detect a second modulated beam from the second optics, and control the rotating unit based on at least one parameter of the second modulated beam.

The invention discloses a low-output-ripple ultralow-offset-voltage operational amplifier and a working method thereof. The low-output-ripple ultralow-offset-voltage operational amplifier comprises a first chopper circuit, a first-stage operational amplifier additionally provided with an offset voltage adjusting circuit, a second chopper circuit, a notch filter, a second-stage operational amplifier and a third-stage operational amplifier which are sequentially connected. The offset voltage adjusting circuit trims the input offset voltage of the first-stage operational amplifier to hundreds of microvolts and then outputs the offset voltage to the second chopper circuit; the first chopper circuit and the second chopper circuit are used for modulating the offset voltage of the first-stage operational amplifier to a chopping frequency, and then the ripple voltage at the chopping frequency is filtered by the notch filter; the first-stage operational amplifier is designed to be a high-gain amplifier so as to restrain input offset voltage errors caused by the second-stage operational amplifier and the third-stage operational amplifier. According to the invention, low output ripple voltage and ultralow input offset voltage can be realized only by using the wave trap with a small area.

First and second bases are arranged to face each other. An inverter is mounted on either of the first and second bases. A converter is mounted on the first base. A chopper is mounted on the second base. At least some of fins thermally connected to the converter via the first base are thermally connected to the chopper via the second base.

The invention relates to the technical field of robot intelligent actuators, and discloses a magneto-rheological end effector accurate grasping system based on force feedback, which comprises a multi-curved-surface bionic fingertip formed by a magneto-rheological elastomer, and a three-dimensional distributed excitation coil array is embedded in the fingertip. The coil array is excited by a high-frequency chopping constant-current driving module to generate a space gradient magnetic field, and the magnetic field changes the shear modulus of the elastomer within millisecond-level time, so that the fingertip surface hardness jumps in real time along with a control instruction; and the force feedback closed-loop control unit comprises an ultrathin film strain sensing net attached to the inner curved surface of the fingertip. Through time-sharing switching of a negative pressure micropore adsorption layer and a magneto-rheological rigidity keeping mode, traditional adsorption and rigid clamping are changed into a pre-fixing and rigidity gradual change two-section type process, instantaneous force impact during adsorption release is eliminated, meanwhile, thin film wrinkling caused by continuous negative pressure is avoided, and it is ensured that an ultrathin and high-added-value workpiece is kept flat and traceless in the whole transfer process.

The invention discloses a hydrogen production power supply system and a control method thereof. The system comprises a transformer, a main power branch, an auxiliary power branch, at least one group of energy storage branches and a bus bar, a primary winding of the transformer is coupled to an alternating current power grid, and a secondary winding is coupled to the input end of the main power branch; the output end of the main power branch is coupled to the off-grid hydrogen production equipment; the auxiliary power branch is coupled between the secondary winding and the bus bar; the energy storage branches are coupled to the bus bar; the main power branch comprises at least one group of uncontrolled rectifying circuits and at least one group of chopper circuits, the uncontrolled rectifying circuits are used for converting alternating current output by the transformer into direct current, the cost is low, and the chopper circuits are used for adjusting the voltage of the direct current into the voltage required by a load of the chopper branch; the auxiliary power branch is used for outputting power to the bus bar and performing power interaction with an alternating current power grid to improve the response capability to the alternating current power grid; and the energy storage branch is used for pre-storing and releasing electric energy through the bus bar, so that the system stability is improved.

The invention provides a zero-voltage ride-through control method for a self-synchronizing voltage source doubly-fed wind turbine generator, which comprises the following steps that: when the self-synchronizing voltage source doubly-fed wind turbine generator is in a transient state, a grid-side converter adopts vector control, and a rotor-side converter adopts additional virtual impedance and annular current limiting; the transient overcurrent of the grid-side converter and the rotor-side converter can be effectively suppressed, so that the continuous operation capability of the wind turbine generator in the zero-voltage ride-through period can be maintained; meanwhile, by improving the transient capacity and the transient reactive current amplitude of the converter, the transient voltage supporting capacity of the wind turbine generator during the zero voltage ride-through period can be effectively provided; when the self-synchronizing voltage source doubly-fed wind turbine generator set is in a transient state, overvoltage of direct-current bus voltage is limited by a Chopper circuit, active-priority current amplitude limiting control is adopted by a grid-side converter, parameters of a current inner ring PI controller of a rotor-side converter are optimized, energy balance of a direct-current side can be achieved in the zero-voltage ride-through period, and stability of the direct-current bus voltage is maintained.

A voltage detection circuit includes an AD converter, an input chopper circuit, an output chopper circuit, a digital low-pass filter, and a current chopper circuit. The chopper circuit switch a connection state of each input terminal of the AD converter, first and second input wirings at a first frequency. The output chopper circuit alternately execute inverting and non-inverting operations for an output value of the AD converter. The digital low-pass filter removes a high-frequency component from the output value of the output chopper circuit and operates at an output frequency. The current chopper circuit switches the connection state of a first current source, the first input wiring, a second current source and the second input wiring at a second frequency.

The invention discloses a transient reactive characteristic modeling method for a flexible excitation system under a power grid voltage fault, and the structure and a control block diagram of the system meet the following requirements: a synchronous generator is connected with a three-phase voltage source type converter, the three-phase voltage source type converter is connected with a chopping converter, the chopping converter outputs excitation voltage according to a system control signal, and the excitation voltage is converted into the excitation voltage. Therefore, excitation current is provided for the synchronous machine. The modeling process comprises the following steps: analyzing a synchronous machine equivalent diagram and an AVR control block diagram in the flexible excitation system so as to establish a corresponding mathematical model; then voltage and current parameters of a synchronous machine end of the system in a steady state before a fault are calculated; the transient current caused by the stator voltage change and the excitation voltage change is further solved respectively; and finally, the transient reactive power of the synchronous machine side of the flexible excitation system is obtained. The method provides a theoretical basis for realizing dynamic strong excitation control of the flexible excitation system and improving the stability of the system under a transient condition.

Provided is a potentiostat-based electrochemical sensor detection device. The device comprises: a digital-to-analog converter (DAC) configured to receive a digital signal from a waveform generator and digital logic and output an analog signal corresponding to a reference voltage; a control amplifier (CA) configured to receive the analog signal corresponding to the reference voltage and apply the reference voltage to a reference electrode (RE); a gain-boosting current mirror configured to copy a sensor current of an electrochemical sensor and output a copied sensor current; a transimpedance amplifier configured to convert the copied sensor current into a voltage signal; a low-pass filter configured to block a high-frequency band signal component of the voltage signal; and an analog-to-digital converter (ADC) configured to perform digital signal processing on a signal having passed through the low-pass filter, wherein at least one of the gain-boosting current mirror and the transimpedance amplifier employs a dynamic element matching (DEM) technique using a plurality of choppers and a plurality of DEM clock signals.

The invention discloses a superconductive phase modifier excitation power unit with adjustable top value voltage and a control method thereof, and the power unit comprises the following modules which are connected in sequence: the input end of a PWM rectifier module is connected with an excitation power supply, and AC / DC conversion is carried out on the input voltage of the excitation power supply; the DC bus support capacitor module realizes output DC voltage support of the PWM rectifier module; the DC chopper module realizes DC / DC chopping output of the DC bus voltage according to the excitation requirement of the generator; the voltage smoothing module is used for smoothing and filtering the chopping pulse voltage output by the direct current chopper module; and the output end of the voltage commutation module is connected with the superconducting rotor and is used for realizing rectification of rotor excitation current and conversion of an inversion loop. According to the technical scheme, the excitation voltage and the excitation current can be adjusted stably in the steady state, the effect of the high excitation multiple can be exerted in the transient state and the dynamic state to improve the quick response capacity of the system, and meanwhile the excitation inversion capacity is achieved to achieve quick reduction of the excitation current.

The invention relates to a dynamic ripple elimination circuit for a linear Hall signal amplifier, and belongs to the technical field of circuits. The dynamic ripple elimination circuit for the linear Hall signal amplifier comprises a ripple extraction network, a fully differential integrator, a chopper and a disappearance tone buffer which are connected in sequence, and the ripple extraction network extracts ripple signals in output signals of the amplifier; and through integration, chopping and buffering, a compensation signal for eliminating ripples is generated and injected into a main loop of the amplifier, and the ripples in an output signal of the linear Hall signal amplifier are eliminated. Therefore, a low-pass filter does not need to be adopted at the rear stage, adverse effects on the bandwidth are avoided, and the circuit is simple in structure and quite wide in application range.

The invention discloses a ping-pong self-stabilization zero-loop ripple suppression precision operational amplifier, which comprises a high-frequency path and a low-frequency path, and is characterized in that the high-frequency path comprises a third transconductance amplifier Gm3 and a fourth transconductance amplifier Gm4; the low-frequency path comprises a first transconductance amplifier Gm1-Gm3, a second transconductance amplifier Gm1-Gm3, a first chopper Cop1-Cop2, a second chopper Cop1-Cop2 and a ping-pong self-stabilization zero ripple suppression loop, and the ping-pong self-stabilization zero ripple suppression loop is used for suppressing offset voltage and output ripple generated by the low-frequency path. The invention designs a ping-pong self-stabilizing zero ripple suppression feedback (AZCFB) loop, the self offset voltage of the ripple suppression loop is eliminated by adopting an automatic zeroing technology, and the residual offset is filtered by a chopper and a filter. In addition, a high-pass filter is used for eliminating the influence of AZCFB loop sampling node direct-current potential deviation on output ripples, and the purpose of restraining the output ripples is achieved.

The disclosure is directed to a brake chopper, a control board, a bus voltage control method, a device and a medium. The brake chopper may include a resistor module, electrically connected to a DC bus to form an energy release circuit of the DC bus; a control module, for determining the difference between a voltage value of the DC bus and a preset first threshold, and generating a first switch control signal on the basis of the difference; and a switch module, for controlling the ON time of the energy release circuit on the basis of the first switch control signal. There may be a progressively increasing relationship between the ON time and the difference. The ON time of the energy release circuit may be precisely controlled based on the difference between 10 the DC bus voltage value and the first threshold, increasing the energy utilization rate of the DC bus.

A gyro sensor circuit includes a gyro sensor generating a radio frequency (RF) sensing signal according to an angular movement of the gyro sensor, and an RF sensing path comprising a first chopper comprising a chopping switch, and configured to chop a tone signal at a chopping frequency to generate a chopped tone signal, an adder configured to insert the chopped tone signal to the RF sensing signal to produce a combined RF sensing and tone signal, and a first demodulator configured to mix the combined RF sensing and tone signal with a local oscillator (LO) signal to output a demodulated signal. The tone signal may be the LO signal. The gyro sensor circuit further comprises a sense base band path comprising a first analog-to-digital converter configured to sample the demodulated signal to output a digitized signal, and a first digital signal processor to extract various signals to be analyzed.

A locomotive has DC or AC traction motors, powered by a hydrogen fuel cell, and optionally other sources such as regenerative braking. The traction motors of the locomotive may be connected to a set of independent DC choppers or AC inverters, linked via a common DC bus, configured to regulate power from the one or more power sources. A manager module, among other functions, may receive inputs and signals to coordinate delivery of electricity from the sources to the motor. A method for retrofitting a legacy locomotive may include removing a generator and a control apparatus configured for diesel fuel, and installing a kit of apparatus configured to be powered by a hydrogen fuel cell. A railway system for use by locomotives powered by hydrogen has one or more hydrogen-generation stations deployed near a track of the railway system.

A bidirectional chopper selectively performs a charging operation and a discharging operation, the charging operation being an operation in which a part of DC power generated by a converter is stored in a power storage device, the discharging operation being an operation in which DC power of the power storage device is supplied to an inverter. A control circuit controls the bidirectional chopper to perform the discharging operation when a power failure of a power system occurs. The control circuit controls the bidirectional chopper based on a system frequency detected by a frequency detector when the power system is normal. The control circuit controls the bidirectional chopper to perform the charging operation in response to an increase in the system frequency, and to perform the discharging operation in response to a decrease in the system frequency.

A DFIG wind power facility configured to be operated during grid faults is provided. The wind power facility includes a Doubly-Fed Induction Generator, a control system, an electric converter, a short-circuit controlled switch to selectively short-circuit the stator and a Stator Neutral Brake Chopper coupled to the stator. The DFIG includes a rotor and a stator, the stator including at least one three-phase winding. The electric converter includes a Machine Side Converter, a Grid Side Converter and a DC link connected therebetween. The SNBC includes a three-phase rectifier including three inputs, an impedance and an active high-frequency switch configured to vary the average value of the impedance by adjusting its duty cycle; each of the three inputs of the rectifier is connected to a phase of the at least one three-phase winding of the stator. Methods for operating a DFIG wind power facility during grid faults are also provided.

The invention provides a driving circuit of a chopping switch circuit and electronic equipment, the driving circuit of the chopping switch circuit comprises a floating power supply generation circuit and a level shift circuit which are electrically connected with the chopping switch circuit, and the driving circuit provides port voltage bias for the chopping switch circuit through the floating power supply generation circuit. The floating power supply and the floating ground change along with the common-mode change of an input signal, so that the conduction impedance change and the threshold voltage change caused by the common-mode level change can be reduced; meanwhile, a power supply and a reference ground are provided for the level shift circuit, so that the level shift circuit can convert an originally constant high-amplitude clock signal into a clock signal changing along with the input common-mode level, and the amplitude of the clock signal can be kept at a constant and low value; therefore, low noise injection and clock feed-through can be realized under the condition that the conduction impedance and the threshold voltage are relatively stable, so that the precision and the stability of the circuit are improved, and the signal quality is improved.

The invention provides a dual-mode parallel competition-dominated self-synchronizing voltage source wind turbine generator set and a control method thereof, and the wind turbine generator set comprises a wind power generation device which is composed of a wind turbine and a generator and is used for converting wind energy into electric energy; the alternating current / direct current conversion module consists of a power electronic converter and a chopper circuit and is used for realizing conversion between alternating current electric energy and direct current electric energy and realizing unloading when transient direct current voltage exceeds the limit; the self-synchronizing voltage source generation control module is composed of a dual-mode parallel competitive dominant control module, a modulation voltage control module and a synchronous phase angle control module and is used for autonomously establishing voltage, autonomously synchronizing a power grid and supporting transient frequency and voltage of the power grid; according to the direct current bus voltage and the power grid voltage, the self-synchronizing voltage source characteristics of the unit under multiple operation working conditions such as wind speed disturbance and power grid faults are maintained through state keeping and competitive leading of the two voltage source control modes. The invention is suitable for doubly-fed and full-power wind turbine generators, and comprises control, equipment and a system.

According to one embodiment, a chopper stabilized amplifier includes an input unit, a first chopper, a first amplifier, and a switch circuit. The input unit receives a differential input signal at a first input terminal and a second input terminal. The first chopper modulates the differential input signal based on a first control signal and an inverse signal of the first control signal. The first amplifier amplifies the signals with the modulated differential output from the first chopper. The switch circuit is provided between the input unit and the first chopper, and receives a second control signal and reduces input currents which flow in the first chopper when the first chopper performs a modulating operation, by using an operation with the second control signal.

A hardware (e.g., a process and / or circuitry) and / or software-based controller for septic system grinder or chopper units monitors load to the unit. As the unit encounters debris, electrical and mechanical load on the unit increases. In some cases, a signal to stop the unit from grinding / chopping (including but not limited to a signal based a waste-water level) is received while the unit is under the increased load. The controller may override the stop signal and continue sending power to the unit to clear the unit from debris causing increased load. The override may cease when it is determined that the debris has been cleared, such as when it is determined that the increased mechanical and / or electrical load on the unit has decreased or returned to a target load, allowing the unit to stop. The unit may include self-configuration functionality, determining thresholds for signaling override, target load, etc.