1905 results about "Overcurrent" patented technology

The invention discloses a primary and secondary fusion pole-mounted intelligent circuit breaker. The primary and secondary fusion pole-mounted intelligent circuit breaker comprises a fault detection module, a protection action module, a reclosing module and an information reporting module, the fault detection module collects multi-dimensional electrical quantity through a current transformer and a voltage transformer, and judges a fault and identifies the type in combination with a dynamic normal range and a duration threshold. The protection action module calculates the fault distance based on the correction impedance, judges whether to act or not by combining the current flow direction and the protection range, and selects a protection level according to the fault severity; the reclosing module dynamically sets an observation time window, distinguishes instantaneous or permanent faults through a retest verification mechanism, and adaptively adjusts a reclosing strategy; and the information reporting module uploads fault related information. According to the method, the problems of high misjudgment rate, poor protection selectivity, rigid reclosing logic and the like of a traditional circuit breaker are solved, and the accuracy, quickness and self-healing capability of power distribution network fault processing are remarkably improved.

The invention discloses an insulation detection method for an electric automobile, belongs to the technical field of high-voltage safety monitoring of the electric automobile, and solves the problem that the insulation detection precision is reduced due to electromagnetic interference, impedance fluctuation and capacitive effect coupling in a dynamic load switching process. According to the scheme, a test sequence of discrete frequency points is applied to a high-voltage system; measuring a response current value through a current sensor and calculating a ground distributed capacitance value; connecting a test voltage source between positive and negative electrodes of the high-voltage system through a coupling circuit; applying a first pulse signal during no-load, dynamically setting the width according to the capacitance value, measuring a first response current value, and calculating an initial insulation resistance value; a second pulse signal with the same parameter is applied in the load state window, a second response current value is measured, and differential filtering is carried out in combination with the initial value to eliminate load noise; and comparing the filtered insulation resistance value with a threshold value, and outputting a fault signal when the insulation resistance value is lower than the threshold value. The method is used for monitoring the insulation state of the high-voltage system in real time and accurately early warning faults.

The invention relates to the technical field of wiring terminals, in particular to an intelligent testing method and system for the contact resistance of a wiring terminal, and the method comprises the following steps: adjusting the resistance testing frequency according to the environment temperature to adapt to different conditions, combining current and voltage data, analyzing the historical change trend of the resistance, predicting the potential change range, and obtaining the contact resistance of the wiring terminal through the current and voltage data. Evaluating the mutual influence with the resistor, judging the abnormal reason of the resistor, adjusting a test scheme according to fault diagnosis, predicting potential faults, and making a test plan. According to the invention, through environment induction and data analysis, the resistance test frequency is adjusted in real time to adapt to environment change, so that the resistance measurement in the test process is more sensitive and accurate, the response speed and data quality of the test process are improved, historical and current resistance data are automatically analyzed, potential faults can be effectively predicted and identified, and the test efficiency is improved. Problems caused by operation errors are reduced, and a prospective fault prediction function enables the adjustment of the test period to be more scientific.

The embodiment of the invention discloses a midpoint potential control method based on a diode clamping type three-level grid-connected inverter and a related device. The method comprises the following steps: generating an initial three-phase modulation wave through a current loop closed-loop control method according to a collected three-phase current value and a three-phase voltage value of a power grid side of the diode-clamped three-level grid-connected inverter; according to an initial modulation waveform generated by the initial three-phase modulation wave, a three-phase current value and an acquired voltage value of a voltage dividing capacitor at the direct current side of the diode clamping type three-level grid-connected inverter, calculating a zero-sequence component required by neutral-point potential balance; superposing a zero-sequence component required by neutral-point potential balance with the initial modulation waveform to obtain a final modulation wave; and generating a driving signal matched with each phase of bridge arm in the diode clamping type three-level grid-connected inverter according to the final modulation wave. By adopting the invention, the neutral-point voltage can be balanced, the distortion of the output waveform at the alternating current side is reduced, the voltage stress of the device is reduced, and the service life of the power device is prolonged.

The invention discloses a driving control method of a DAB converter and related equipment, and relates to the technical field of power electronic converter control, and the method comprises the steps: calculating a voltage transformation ratio based on an input voltage and an output voltage through a current stress adjustment module, and calculating an output power based on the output voltage and an output current, substituting the voltage transformation ratio and the output power into a current stress adaptive minimization algorithm to solve an internal phase shift angle; meanwhile, through a PI controller, an external shift phase angle is adjusted based on a difference value between the instruction voltage and the output voltage; outputting the inner phase shift angle and the outer phase shift angle to a PWM modulation generator to generate a switching tube driving signal; the DAB converter is controlled by the driving signal to realize rated voltage output and current stress minimization, so that the efficiency and reliability of the converter are improved.

The invention discloses a CPLD-driven IGBT short-circuit current dynamic monitoring method and system, and relates to the technical field of power electronics, and the method comprises the specific steps of S100 real-time data acquisition, S200 dynamic threshold calculation, S300 short-circuit state judgment, S400 rapid protection execution, and S500 fault data recording and uploading. Accurate and prospective judgment of the short circuit state of the IGBT is achieved, two stress parameters including the direct-current bus voltage and the junction temperature serve as independent variables, when the bus voltage rises, the voltage stress borne by the IGBT in the turn-off period is increased, meanwhile, the current peak at the short circuit moment is more remarkable, early warning is conducted in advance by dynamically lowering the threshold value, and therefore the short circuit state of the IGBT is accurately judged. According to the mechanism, the monitoring system does not simply respond to the occurred overcurrent, but can pre-judge the safety boundary of the device under the current working condition, so that intervention is implemented before the current really reaches a dangerous peak value, and a protection blind area under a severe working condition is effectively avoided.

The invention provides a fault ride-through control method and a fault ride-through control system for a grid-forming converter, which are characterized in that the current of the grid-forming converter under an asymmetric fault is controlled by adopting a negative-sequence current reference generation strategy aiming at an inner ring of a controller, and negative-sequence reactive current is injected into a power grid; adopting a partial sequence current amplitude limiting strategy to control the maximum phase current amplitude of the injected asymmetric current not to exceed an amplitude limiting value; controlling the boundary of an active reference value by adopting an active reference value amplitude limiting strategy for an active synchronization ring; a synchronous damping link is adopted to enhance damping in power angle swing; for a reactive voltage loop, a reactive voltage variable coefficient control strategy is adopted to control the output of the maximum reactive current; and an internal potential locking strategy is adopted to suppress overvoltage. According to the invention, negative-sequence reactive power is provided, and overcurrent of each phase is avoided; the power angle characteristic is improved, and the transient stability is improved; stable transient voltage support is provided in a current output capability range; and after the fault is recovered, the voltage of the converter grid-connected point is smoothly recovered.

A low voltage ride through control method for a grid-forming inverter based on dynamic internal potential adjustment comprises the following steps: detecting a voltage per unit value of a grid-connected point in real time, and comparing the voltage per unit value with a threshold value to judge a voltage drop event and trigger low voltage ride through control; dynamically calculating active and reactive power reference values through a reactive compensation equation and an active current limiting equation according to the voltage amplitude and the power reference value before falling during the ride-through period; inputting the active reference value into a virtual rotor motion equation to generate a reference phase, and outputting a phase reference signal in combination with a dual-mode phase compensation controller; superposing the reactive reference value with the reference voltage through a reactive voltage regulating ring to generate a voltage amplitude reference signal; synthesizing an internal potential according to the phase and the amplitude reference signal, and obtaining an inductive current reference value through virtual impedance control and current amplitude limiting; and finally, a driving signal is generated through the current inner loop controller and the modulation module. According to the invention, overcurrent can be effectively inhibited, rapid reactive power support is provided, and synchronous stability and smooth transition in a fault period and a recovery process are ensured.

The invention relates to a BUCK-BOOST converter control circuit, a control method and a safety air bag chip, the peak value of inductive current is detected through a current sampling compensation module, stable control of output voltage is achieved, the dynamic response speed is high, the loop stability is good, and meanwhile the circuit structure is simple. According to the BUCK-BOOST converter, stable switching of the working modes of the BUCK-BOOST converter is achieved through the mode control module, and it is ensured that the BUCK-BOOST converter can still work normally under the high voltage level. And the slope compensation unit is introduced into the circuit, so that subharmonic oscillation can be effectively prevented when the duty ratio of the PWM signal is greater than 50%, and the stability of the system is ensured.

The invention relates to the technical field of power system monitoring, and provides a power grid data fault diagnosis method and device based on an intelligent power monitoring instrument, and the method comprises the steps: collecting the operation data of a power grid through the intelligent power monitoring instrument, and generating a fault feature vector containing the multi-dimensional feature parameters of voltage, current and power factor; matching and comparing the feature vector with a preset fault criterion; determining a specific fault type based on a comparison result of the characteristic parameters and a threshold value, including identifying voltage abnormity through a voltage deviation rate, identifying harmonic exceeding through a current harmonic total distortion rate, and identifying a three-phase imbalance fault through a three-phase imbalance degree; for judgment of the three-phase unbalance degree, mean square error statistic calculation is adopted, and a safety coefficient is introduced for threshold comparison; and the fault influence priority is evaluated by quantifying the degree of deviation of each characteristic parameter from the threshold. The fault diagnosis efficiency and reliability can be improved, and intelligent decision support is provided for safe operation of a power grid.

The invention provides a current measuring circuit which comprises a micro-control unit and at least two measuring range circuits, and each measuring range circuit comprises a resistor, an MOS tube and an operational amplifier. The resistor of the previous measuring range circuit is connected in series with the resistor of the next measuring range circuit, the resistor of the first measuring range circuit is connected with power supply equipment, and the resistor of the last measuring range circuit is connected with a load to be measured; the micro-control unit is used for traversing the output voltage of the operational amplifier of each range circuit in sequence; if it is determined that target voltages on the two sides of a resistor of the measuring range circuit are smaller than a preset threshold value based on the output voltage, target current of a to-be-measured load is determined based on the output voltage and the resistance value of the resistor; and if the target voltage is not less than the preset threshold value, continuing to traverse the output voltage of the operational amplifier of the next range circuit. According to the technical scheme of the invention, the current measurement circuit meets the measurement requirements of a plurality of current ranges, the current ranges can be automatically switched, and the current output is not interrupted.

The invention relates to the technical field of power distribution network fault early warning systems and methods, in particular to an intelligent power distribution network fault early warning system and method based on the Internet of Things, and the system comprises a sensing unit, a data processing unit, a data analysis unit, a fault early warning unit, a monitoring management unit, and a personnel inspection subsystem unit. The sensing unit is used for installing a current sensor, a voltage sensor, a temperature sensor and a humidity sensor at key node positions of a transformer, a switch cabinet and a line of the power distribution network, the current sensor is used for monitoring the current in the line in real time, the voltage sensor is used for monitoring the voltage value, and the temperature sensor is used for monitoring the operating temperature of equipment; faults are analyzed and judged from multiple angles, misjudgment and missed judgment are reduced, whether fault hidden dangers exist or not is judged more accurately, the operation state of equipment is evaluated in real time through monitoring of the Internet of Things, the frequency of manual inspection is appropriately reduced, the labor cost is saved, and the resource utilization efficiency is improved.

The invention provides a device for inhibiting drain-source overvoltage and overcurrent through active gate drive of a silicon carbide MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), aiming at solving the problem of voltage or current overshoot caused by circuit parasitic parameters in a high-speed switching process of the SiC MOSFET and simultaneously considering the switching speed and energy loss balance. According to the device, drain-source voltage vdc and direct-current bus voltage of the SiC MOSFET are collected to serve as feedback signals, and gate driving voltage and equivalent gate resistance are dynamically adjusted; in a key stage (a Miller plateau switching-on period and a voltage rising period switching-off period) of a switch transient state, a gate resistance network is switched through a logic control circuit, and suppression of drain current overshoot and drain-source voltage overshoot is realized. Simulation verification shows that the device can reduce voltage overshoot by 20%-30% and current overshoot by 25%-60%, only a single voltage feedback channel is needed, the cost is obviously lower than that of a traditional multi-signal acquisition active gate driving scheme, and the device is suitable for a high-efficiency SiC MOSFET power converter.

The invention discloses a power adapter parameter dynamic optimization method for prolonging the service life of equipment, and relates to the technical field of adapter performance optimization, and the method comprises the steps: monitoring and recording the output voltage, current and power factor parameter changes of a power adapter in real time under static and dynamic load conditions by using a test instrument; identifying the trend and reason of abnormal parameter change; performing thermal design optimization and temperature management on the power adapter; performing over-power and over-current limitation on the pulses one by one; introducing a power factor correction circuit; optimizing the switching frequency and the design of an output filter; a load line adjusting circuit is introduced, and space is reserved for dynamic ripples when output current jumps; and evaluating whether the optimization effect reaches an expected target or not. By introducing the power factor correction circuit and the load line adjustment circuit, the power factor of the power adapter is improved, the harmonic pollution is reduced, the stability of the output voltage of the power adapter is improved, and the performance of the power adapter under the dynamic load condition is improved.

The invention belongs to the field of overvoltage protection, and relates to an overvoltage stabilizing and protecting device which comprises a data acquisition operation module, a control logic module, a display module, an overvoltage protecting assembly and a high-voltage vacuum circuit breaker or an electric isolation handcart structure. The real-time monitoring and protection of the working state of the overvoltage protection assembly are realized; through the arrangement of the high-voltage circuit breaker or the electric isolation handcart, when the overvoltage protection assembly is detected to be abnormal, the connection between the overvoltage protection assembly and the high-voltage bus can be rapidly cut off, so that the system safety is ensured; the device integrates a transient fault recording function and can capture wave map data before and after a power frequency overvoltage fault of the system; the overvoltage protection assembly in the device adopts a geometric center air cooling heat dissipation mode, the fan is quick in starting response, the operating temperature of the overvoltage protection assembly is greatly reduced, the operating time of the overvoltage protection assembly can be effectively prolonged, and the device adopts an integrated modular structural design, so that the operation safety, the maintenance and the management are greatly facilitated.

The invention discloses an optimized fault-tolerant control method suitable for a cascaded solid-state transformer. On the basis of the basic control link of the cascade converter, the bus voltage of each normally operating cascade module in the switching process and the bus voltage of the redundant module are detected, and according to the current modulation signal of each cascade module, the new modulation signal of each cascade module is dynamically calculated and obtained; the fluctuation of voltage and current in each stage of the switching process can be reduced. According to the invention, the problem that the current impact is too large when the whole system is switched due to the fault of one cascade module in the cascade converter is solved. According to the method, no additional circuit needs to be added, smooth switching of the cascade converter can be achieved when the fault occurs, the whole system can continue to work stably, and collapse of the whole system caused by over-current protection is prevented.

To provide a biological vector potential generating apparatus that is capable of suppressing the resistance and inductance of a solenoid coil and conducting a large current.SOLUTION: A biological vector potential generating apparatus 1 includes a vector potential coil 10 which is formed by winding a solenoid coil formed by winding conductors 22a to 22d connected in series with core wires 21a to 21d along substrates 30a to 30d with an insulation property. The apparatus further includes an oscillator 36 and amplifiers 31 to 34 that are connected to the oscillator 36 and connected to respective vector potential coils 10a to 10d. The vector potential coils 10a to 10d are stacked such that the central axes of the substrates 30a to 30d are aligned. By supplying current to the vector potential coils 10a to 10d connected to the amplifiers 31 to 34, a vector potential is generated within the internal space.SELECTED DRAWING: Figure 1

The invention provides a high-precision current limiting circuit of an LDO (Low Dropout Regulator) with an NMOS (N-channel Metal Oxide Semiconductor) tube as a power tube, which is applied to the technical field of current limiting circuits and comprises a voltage loop and a current loop, and the voltage loop is used for monitoring and stabilizing the output voltage VOUT of a power tube NM1; and the current loop is used for acquiring a sampling current according to the load current of the power tube NM1, comparing the sampling current with a reference current IREF, and when the sampling current is higher than the reference current IREF, driving and controlling the output voltage VOUT of the power tube NM1 to be reduced so as to limit the load current of the power tube NM1 to continue to rise. When the LDO works normally, the output voltage VOUT of the power tube NM1 is stabilized through the voltage loop, and when the load current is too high, the output voltage VOUT of the power tube NM1 is driven and controlled to be reduced through the current loop, so that the load current of the power tube NM1 is prevented from continuing to rise, and the stability and the safety of the LDO are improved.

The invention provides a new energy grid-connected converter fault ride-through method and system under an asymmetric fault, and the method comprises the steps: calculating the positive sequence voltage amplitude of a power grid and the voltage unbalance degree of the power grid according to the positive and negative sequence parameters of the power grid; judging whether the power grid is in a normal state or a fault state; when the power grid is in the asymmetric fault state, current amplitude limiting is carried out by adopting a calculation formula of a positive and negative sequence current instruction in the asymmetric fault state based on the related parameters of the power grid fault, and the amplitude limiting value of the positive and negative sequence current instruction of the new energy grid-connected converter in the asymmetric fault state is calculated; feedback control is carried out according to the amplitude limiting values of the positive and negative sequence current instructions, and fault ride-through is completed; according to the method, the current is subjected to amplitude limiting in the calculation formula of the positive and negative sequence current instructions, so that the positive and negative sequence active and reactive current control target can be met to the greatest extent on the premise of ensuring that overcurrent of the converter does not occur, and the power grid supporting capacity during the fault period is improved.

The invention belongs to the technical field of electrical equipment fault monitoring, and discloses a fault monitoring system for electromechanical installation engineering, which comprises a high-impedance fault identification module, extracts nonlinear harmonic features through current signals, constructs a frequency domain-time domain joint feature set in combination with space-time magnetic distortion in an electromechanical installation process, and performs fault identification on the nonlinear harmonic features through the high-impedance fault identification module. Non-linear characteristic response identification of the high-impedance fault is carried out, and a high-impedance fault characterization result is output; the transient fault capturing module is used for positioning a risk time window according to a high-impedance fault characterization result, and identifying the starting and ending boundaries of an electrical disturbance behavior in combination with a double-threshold mutation mechanism; synchronously extracting corresponding operation condition parameters, constructing a short-time process behavior model taking electrical disturbance as a source, and outputting a transient disturbance sequence; and the sensitivity of fault identification, the accuracy of positioning and the real-time performance of diagnosis are integrally improved.

The invention discloses a high-voltage cable outer metal sheath grounding defect on-line monitoring method and monitoring system, which can work under the condition that a cable is not powered off, realizes on-line monitoring, and realizes on-line monitoring through the cooperation of a current sensor, a voltage sensor, a single-chip microcomputer and an upper computer. And the equipment can quickly detect when a fault occurs and is convenient for maintenance workers to timely eliminate obstacles, so that the risk of major electric power accidents is reduced. The algorithm is similar to an improved neural network algorithm and is used for diagnosing the defects of the outer metal sheath of the cable, the weight is obtained through training learning, and finally the defects of the outer metal sheath of the high-voltage cable are determined. The protection content covers each component of the technical scheme, and comprises a monitoring method, a device structure, a sensor technology, a data processing algorithm, a neural network learning algorithm and the like.

The invention relates to the technical field of motor starting control, and discloses a large-current starting method suitable for a direct current motor, and the method comprises the steps: continuously monitoring the temperature data in the starting process of a driving motor through a temperature detection module, and collecting the current data in the starting process through an OCP detection module; collected temperature data and OCP monitoring characteristics are input into the restart logic module in a delayed mode, the restart logic module judges whether restart is conducted or not according to a preset algorithm and generates a first restart instruction or a second restart instruction, and the bridge drive circuit controls the motor to be started and restarted according to the received instruction till the motor is started successfully. By monitoring temperature and current data in real time, damage caused by overheating or overcurrent of the motor can be effectively prevented, the restart period is dynamically adjusted, the success rate of starting of the driving motor is increased, starting failure caused by overcurrent protection or overheating protection is avoided, and the service life of the motor is prolonged. The problem that in the prior art, when a large-capacity direct-current motor is started, current interruption is prone to occurring is solved.

The invention discloses an active damping control system for improving the output impedance of a current source type inverter, which comprises a current loop control loop, an active damping branch and an improved phase-locked loop, and is characterized in that the difference value of reference current and feedback network access current passes through a current controller to form the current loop control loop; the voltage of the grid-side inductor is fed back to the output of the current loop through the virtual resistor link to form a damping branch, and the voltage of the common coupling point enters the traditional phase-locked loop link through the low-pass filter and forms an improved phase-locked loop through phase compensation. The optimal feedback coefficient of the damping branch is designed according to the optimal damping ratio, the low-pass filter parameters are designed according to the phase at the maximum resonant frequency, the reasonable proportional gain link is designed according to the improvement of the output impedance amplitude, the resonance of the current source type inverter can be effectively inhibited, the output impedance of the inverter is increased, and the output impedance of the inverter is improved. And the quality of the network access current of the current source type inverter and the stability margin of the current source type inverter in a weak power grid are improved, and the stability of the system is improved.

The invention discloses a feedback field weakening control method and system for a surface-mounted permanent magnet synchronous motor, and the method comprises the steps: collecting a rotation speed feedback value of a motor, and controlling the operation of the motor through employing a maximum torque current ratio if the rotation speed feedback value is smaller than a rated rotation speed; calculating a first flux-weakening rotating speed according to the real-time load rate and the bus voltage fluctuation, and if a rotating speed feedback value of the motor is greater than the first flux-weakening rotating speed, entering a first flux-weakening mode: calculating a difference value between an output voltage amplitude and the bus voltage, generating a d-axis current compensation value, and performing load compensation and rotating speed compensation on the d-axis current compensation value to obtain a d-axis current given value; the maximum value of the q-axis current is calculated, given voltage values of the d-axis and the q-axis are generated, and the motor is driven to operate; and calculating a second flux-weakening rotating speed according to the q-axis current maximum value and the voltage margin, and if the rotating speed feedback value of the motor is greater than the second flux-weakening rotating speed, entering a second flux-weakening mode: further limiting the q-axis current maximum value through a current limit circle and a voltage limit circle on the basis of the first flux-weakening mode.

The invention relates to the technical field of fault detection, in particular to a high-voltage connector loosening fault detection method and device and an automobile, and the method comprises the following steps: forming a surface acoustic wave resonator array based on an interdigital transducer array, an acoustic wave resonator and a flexible waveguide; butting a signal source radio frequency cable with the pin interdigital electrode chip, triggering data acquisition, performing Fourier transform on original data, and judging the loosening risk of the connector according to each parameter threshold value; carrying out three-dimensional modeling on the connector plugging interface, carrying out modal analysis on the model, and obtaining surface acoustic wave frequencies, group velocities and phase distribution under different pre-tightening forces so as to identify a contact force abnormal region; based on a multi-stage early warning mechanism, rapid locking is achieved through electrorheological fluid, and displacement is finely adjusted through a magnetostrictive rod. According to the invention, the loosening hidden danger can be quickly and accurately locked, a tight protection system is constructed by multi-stage early warning and mechanical self-locking, and the loosening risk of the high-voltage connector can be greatly reduced from early warning to active intervention.

The invention relates to the technical field of flexible direct-current power transmission, and discloses a converter control method and device for an offshore wind power flexible direct-current power transmission system, and the method comprises the steps: monitoring the real-time output voltage of a converter, and obtaining the power data and no-load voltage data of the converter when the real-time output voltage is not equal to a preset voltage value; based on the power data and the no-load voltage data, an output voltage reference value is obtained through reactive voltage control; constructing a virtual resistor based on virtual impedance control, and obtaining an output current reference value according to the output voltage reference value and the virtual resistor; obtaining a differential mode voltage according to the output current reference value through current inner loop control; and the real-time output current of the converter is adjusted based on the differential mode voltage, so that the real-time output voltage is adjusted to a preset voltage value according to the change along with the real-time output current. According to the invention, the accuracy of frequency information transmission in the DC power transmission system can be effectively improved.

To provide a power conversion device having an overcurrent protection circuit unit that rapidly detects an overcurrent and protects a semiconductor switching element.SOLUTION: In a power conversion device, an overcurrent protection circuit unit (41) includes a detection signal adjusting means (60) that outputs an adjusted detection signal (I-sens-aj) having a gain adjusted according to a detection signal (I_sens) of a current sensor (21) that detects a phase current and a comparator (61) that compares the adjusted detection signal with an overcurrent threshold (I_thres) to determine an overcurrent and provide an overcurrent stop signal (51) to a drive circuit unit (40).SELECTED DRAWING: Figure 4

The invention discloses a high-voltage switch circuit breaker vacuum bubble arc extinguish chamber vacuum degree on-line monitoring method and device. The method comprises the steps of measuring a main loop current value of a high-voltage switch circuit breaker at the moment of opening and closing through a current transformer; performing spectrum analysis on the main loop current at the moment of opening and closing through fast Fourier transform to obtain an opening and closing arc spectrum value; according to the current on-off current value, calculating the residual electrical life of the contact; and calculating the vacuum degree of the arc extinguish chamber of the vacuum bubble of the high-voltage switch circuit breaker according to the current value of the main loop at the moment of opening and closing, the frequency spectrum value of the opening and closing arc at the moment of opening and closing and the current service life of the contact. And the vacuum degree condition of the high-voltage switch circuit breaker is comprehensively judged by combining the measured current value of the loop when the high-voltage switch circuit breaker is switched on and switched off, the residual electric life of the contact and the arc-extinguishing discharge frequency spectrum at the switching-on and switching-off moment, so that the problem that misjudgment exists when the vacuum degree is judged only by depending on the arc-extinguishing discharge frequency spectrum is solved, and the practical value is higher.

A semiconductor device includes an output element, a temperature detection circuit, a current limiting circuit, and an overcurrent detection circuit. The output element is a power semiconductor element that drives a load, and is turned on by applying a predetermined turn-on voltage to a gate of the output element in a normal state. The temperature detection circuit detects the temperature of the output element as a detected temperature, during the operation of the output element. The overcurrent detection circuit detects an overcurrent state of the output element. When the overcurrent state is detected and the detected temperature exceeds a set temperature, the current limiting circuit sets a gate voltage of the output element to a set voltage lower than the predetermined turn-on voltage. In addition, the current limiting circuit increases the set voltage in stages as the temperature decreases.

According to the pure hardware PID current control system and method based on the direct current brushless motor provided by the invention, the negative voltage interference generated by electromagnetic induction is directly filtered in the bus current signal acquisition stage through the cooperation of the current sampling module and the bus negative voltage elimination module; the problem of signal distortion caused by negative voltage in a traditional sampling circuit is eliminated, and the current effective value detection precision is improved; the PID control module constructed based on pure hardware calculates a difference value between a target voltage and an actual voltage in real time through an analog circuit, and generates a proportional, integral and differential composite compensation signal, so that a PWM modulation circuit can adjust duty ratio output in real time according to the compensation signal, and it is ensured that a bus current of a motor driver is rapidly converged to a target value; the whole scheme does not need to depend on a microcontroller and a complex software algorithm, closed-loop current control is achieved through discrete devices, and the system cost is reduced.