535 results about "Over current protection" patented technology

The invention discloses a high-voltage power amplifier with an over-temperature and over-current protection circuit, and relates to the technical field of integrated circuits. The high-voltage operational amplifier comprises a high-voltage operational amplifier core unit and a self-adaptive protection circuit unit, the high-voltage operational amplifier core unit comprises a rail-to-rail input stage, a gain amplification stage and an AB type push-pull output stage which are sequentially cascaded, and the AB type push-pull output stage comprises a PMOS upper power tube and an NMOS lower power tube; the self-adaptive protection circuit unit comprises a PMOS (P-channel Metal Oxide Semiconductor) current-limiting protection circuit, an NMOS (N-channel Metal Oxide Semiconductor) current-limiting protection circuit and an over-temperature protection circuit; the PMOS current-limiting protection circuit is used for generating a high-voltage domain over-current control signal when the power tube on the PMOS is over-current; the NMOS current-limiting protection circuit is used for generating a low-voltage domain overcurrent control signal when the NMOS lower power tube is in overcurrent; the over-temperature protection circuit is used for generating high-voltage domain over-temperature turn-off signals and low-voltage domain over-temperature turn-off signals when the amplifier is over-temperature; and finally, carrying out logic synthesis on the corresponding over-current control signal and the over-temperature turn-off signal to generate a gate clamping signal.

The invention discloses a frequency converter multi-stage cooperative rapid overcurrent protection circuit, and the overcurrent protection circuit cooperates with an IGBT inverter circuit, an IGBT drive circuit, a current sampling circuit and a master control MCU of a frequency converter to construct a three-stage cooperative protection system composed of hardware-stage extreme rapid protection, hardware-stage rapid protection and software-stage intelligent protection. And independent action and information interaction between the stages can be realized through circuit design. Compared with the prior art, protection blind areas are eliminated, nanosecond-microsecond level extreme protection is achieved, a multiple and high-reliability redundancy protection system is constructed, intelligent grading processing of faults is achieved, and the diagnosability of the system is enhanced.

The invention provides a probe power supply over-current protection circuit and an over-current protection method thereof, relates to the technical field of power electronics, and solves the problems that periodic instantaneous over-current and continuous fault over-current are difficult to accurately distinguish and a control signal and a protection system lack a linkage mechanism in the prior art. In the circuit, a current detection unit generates a single over-current trigger signal when detecting a single over-current event; the central control unit sends a blocking signal after receiving the single overcurrent trigger signal, and sends a reset signal after preset time delay; meanwhile, cumulative counting is carried out on single overcurrent trigger signals, and whether an overcurrent fault occurs or not is judged according to a preset threshold number of times; the output control unit is used for controlling the closing and resetting of a probe power supply under the action of different signals; and the state feedback unit feeds back state information to the main control system when an overcurrent fault occurs. According to the invention, accurate response to the ELM overcurrent of the Tokamak device and reliable blocking of persistent faults are realized.

The invention discloses an intelligent opening and closing method and system for a reclosing circuit breaker based on an electromagnet, and relates to the field of intelligent control, and the method comprises the steps: monitoring a line current in real time, comparing the line current with a preset threshold value, and carrying out the opening after the overcurrent abnormality is detected. Entering a first time delay stage after opening, comprehensively evaluating the states of the circuit breaker and the circuit, and constructing a dynamic weight index system to calculate an evaluation score; if the score exceeds a threshold value, closing is carried out after time delay is finished, otherwise, an alarm is triggered. And entering a second delay stage after switching on, continuously monitoring the electric parameters and establishing an anomaly judgment mechanism, forming a closed-loop protection process of monitoring, switching off, evaluating, switching on and re-monitoring, and realizing intelligent linkage of overcurrent protection and state self-adaption. The method has the advantages that through real-time line electric parameter monitoring, multi-dimensional state evaluation and an intelligent decision-making mechanism, precise opening and closing of the circuit breaker are achieved, the power supply reliability is improved, the power failure time is shortened, and the misoperation risk is reduced.

A short-circuit protection circuit of a half-bridge driving chip relates to the field of short-circuit protection and integrated circuit design, and comprises a pre-driving module for generating a high-side signal and a low-side signal; the half-bridge module is driven, a high-side MOS receives a high-side signal, and a low-side MOS receives a low-side signal; the gate source hardware clamping module is used for carrying out voltage clamping on the high-side MOS when over-current of the over-ground short circuit of the high-side MOS is detected; the phase voltage short-circuit protection module is used for controlling the overcurrent time when the high-side MOS short circuit is over-current, and sending a fault signal to the logic module when detecting that the high / low-side MOS short circuit is over-current; the bus over-current protection module is used for sending a fault signal to the logic module when bus over-current is detected; and the logic module judges whether the short-circuit protection circuit enters a protection state according to the fault signal. According to the invention, the response speed and the protection mechanism are intelligently switched in real time in different overcurrent fault scenes through the three-stage protection circuit, and the circuit has the characteristics of high sensitivity, fast response speed and strong anti-interference capability.

The invention provides an arc suppression coil grounding system zero-sequence overcurrent protection method based on zero-sequence voltage verification. The protection reliability is improved through multi-criterion fusion. The method specifically comprises the following steps: S1, arc suppression coil system fault starting criterion: monitoring a zero sequence voltage in real time, and triggering a protection algorithm when the amplitude of the zero sequence voltage exceeds a preset threshold value; s2, fault time calculation: calculating the duration time of a grounding fault based on the duration characteristic of the zero-sequence voltage; s3, fault position discrimination: in combination with the amplitude characteristics of the zero-sequence current, distinguishing an internal fault from an external fault; and S4, intelligent comprehensive decision making: fusing the transient and steady state characteristic quantities of the zero-sequence voltage and the zero-sequence current, and generating a protection action signal. According to the invention, by dynamically checking the correlation characteristics of the zero-sequence voltage and current, the problems of insufficient sensitivity and high maloperation rate of the traditional zero-sequence overcurrent protection in the arc suppression coil grounding system are effectively solved.

The utility model relates to a kind of compressor inverter overcurrent protection circuit and air conditioner, belong to air conditioning technical field, including rectifier unit, sampling resistance, main control chip, overcurrent protection control switch, fault state self-locking maintenance switch, operational amplifier and voltage comparator.Sampling resistance gathers DC bus voltage signal, after amplification by operational amplifier, it is transmitted to the analog-digital conversion pin and voltage comparator of main control chip.Signal is compared with preset threshold by voltage comparator, low level is output when over threshold, makes overcurrent protection control switch open, rectifier unit is disabled;While fault state self-locking maintenance switch is turned on, and fault pin is locked as low level, realizes overcurrent protection and self-locking.The circuit cooperates by hardware and software, quickly responds overcurrent fault and prevents false restart, improves the security and reliability of air conditioning system.

The invention discloses an overcurrent protection circuit and an overcurrent protection method. In the overcurrent protection circuit, a temperature acquisition unit acquires the environment temperature of an environment where a switch element is located, and sends the environment temperature to a calculation unit; the current acquisition unit acquires an actual current value flowing through the switch element and sends the actual current value to the calculation unit; after receiving the environment temperature and the actual current value, the calculation unit compensates the actual current value by using the environment temperature to obtain a compensation current value, and generates an overcurrent protection signal when the compensation current value is greater than an overcurrent protection threshold value; and the driving unit is connected with the calculation unit, and the driver drives the switching element to be switched off based on the overcurrent protection signal after receiving the overcurrent protection signal sent by the calculation unit. According to the invention, the technical problems that the collected current is inaccurate and fault false alarm or missing alarm is easily caused due to the fact that the conduction impedance of the high-side driving switch is greatly influenced by the temperature in the prior art are solved.

The invention belongs to the technical field of power electronics, and particularly relates to a parallel drive circuit of a silicon carbide power device and a motor drive system.The parallel drive circuit comprises a drive power source, a drive chip, a power switch unit and a plurality of drive shunt units, the current sharing resistor is connected with the auxiliary source electrode of the silicon carbide power device and the common power source electrode node. The problem of current imbalance when a plurality of silicon carbide power devices are used in parallel can be solved, the driving consistency and the system reliability are improved, meanwhile, an overcurrent protection function is provided, and the device is suitable for large-power application scenes such as new energy automobile electric control.

The invention belongs to the technical field of power equipment state monitoring and fault diagnosis, and particularly relates to a dry-type air-core reactor turn-to-turn short circuit early warning method, which comprises the following steps of: establishing a circuit model and a voltage equation set of a dry-type air-core reactor in a normal operation state and a turn-to-turn short circuit fault state; acquiring a voltage signal and a current signal of the dry-type air-core reactor in a running process in real time; calculating one or more key electrical parameters of the dry-type air-core reactor based on the voltage signal and the current signal; comparing and analyzing the calculated key electrical parameters with corresponding preset thresholds or reference parameters in a normal state; and when the variable quantity or the absolute value of at least one key electrical parameter exceeds a corresponding preset range, triggering turn-to-turn short circuit early warning. According to the invention, the early and accurate early warning of the turn-to-turn short circuit fault of the dry-type air-core reactor is realized, and the technical bottleneck of slow action of traditional overcurrent protection is fundamentally broken through.

The invention provides a power-limited resonant converter and converter equipment, and relates to the technical field of electronic circuits. The power-limited resonant converter comprises a primary side circuit, a secondary side circuit, a transformer module and a resonant module, the resonant module comprises at least one resonant capacitor, two ends of each resonant capacitor are reversely connected in parallel with a clamping unit, the clamping units are used for being disconnected when the current of the resonant converter is lower than a preset current, and the resonant converter works in a resonant state. When the current of the resonant converter is not lower than the preset current, the resonant capacitor is conducted and bypassed, and the resonant converter works in a non-resonant state. According to the invention, the voltage of the resonant cavity is limited to the preset value through the clamping units which are reversely connected in parallel, so that the current of the resonant cavity is reduced, the current of a switching tube can be fundamentally prevented from rapidly rising, the primary side current is always in a safe range, a conventional overcurrent protection scheme that primary side driving is blocked by overcurrent of a middle circuit does not need to be adopted, and the reliability of the circuit is improved.

The invention discloses a silicon carbide intelligent power module with voltage and current dual-detection over-current protection, and relates to the technical field of semiconductors. In order to solve the problem that when an existing silicon-based intelligent power module (IPM) is matched with a silicon carbide metal-oxide-semiconductor field effect transistor, due to the fact that the over-current protection response speed is low, interference and false triggering are likely to happen, a dual over-current protection mechanism combining desaturation voltage detection and sub-current detection is adopted. And by mixing and integrating the silicon substrate and the silicon carbide power device, the performance requirements of different application scenes are considered. Three driving control chips, six IGBT chips, six fast recovery diode chips, one SiC MOSFET chip, two silicon carbide Schottky barrier diode chips and one patch sampling resistor are integrated in the module, and all the elements are packaged in the same insulation heat dissipation substrate and lead frame combined structure, so that high integration level, high reliability and fast overcurrent protection are realized; the method can be widely applied to the fields of household appliances, industrial control, new energy and the like.

The invention provides a high-side driving circuit device and method for overcurrent protection and a vehicle, and belongs to the technical field of vehicles. The device comprises a power supply module, an overcurrent protection module, a high-side driving module and a regulation and control module. A regulation and control module is connected with the input end of a high-side driving module, a regulation and control signal is output, on-off of the high-side driving module is controlled according to the regulation and control signal, a driving function is achieved, the high-side driving module is connected with a power module through an overcurrent protection module, the overcurrent protection module detects driving current of a driving power supply, and according to the driving current, on-off of the high-side driving module is controlled. On-off of the driving power supply is controlled, so that on-off of output of the driving power supply to the power supply load is controlled; the over-current protection circuit is constructed by using discrete devices instead of a special high-side driving chip, can trigger the turn-off protection in an over-current scene while realizing the basic function of high-side driving, does not need software monitoring and control, and is high in response speed, high in reliability and low in cost.

The utility model provides a solar charging pile circuit and device, and relates to the field of charging piles. The circuit comprises an input overcurrent protection unit, a countercurrent overcurrent protection unit, a voltage reduction unit, a first power supply generation unit, an input power detection unit, a relay control unit and a charging management unit which are connected in series, and further comprises a second power supply generation unit which is connected with the first power supply generation unit in parallel. According to the circuit, signals are cut off through the input over-current protection unit and the reverse current over-current protection unit when power supply signals are in forward or reverse over-current; the voltage reduction unit is used for reducing the voltage of the power signal; the first and second power generation units are respectively stabilized to different voltages; the input power detection unit is used for monitoring the output power of the solar panel in real time; the relay control unit is used for receiving the trigger signal to cut off the charging loop; the charging management unit is used for adjusting charging current / voltage. According to the scheme, the performance level of the solar charging pile can be maintained and even improved while the circuit structure is simplified and the cost is reduced.

The invention provides an inductor current-limiting protection circuit and method, a DC-DC converter and a chip, and relates to the technical field of DC-DC converters. The inductor current-limiting protection circuit comprises a slope timing circuit which starts timing when a high-side switching tube turn-off signal is detected after the DC-DC converter triggers inductor overcurrent protection, and determines a slope timing voltage based on a target voltage and a preset slope coefficient during the timing period; a reference voltage generating circuit generating a reference voltage according to a power supply voltage and an output voltage of the DC-DC converter; when the slope timing voltage is greater than or equal to the reference voltage, the first comparator determines that the timing time of the slope timing circuit reaches the low-side target conduction time and indicates the low-side switching tube driving control module to control the low-side switching tube of the DC-DC converter to be switched off; the low-side target conduction time is the conduction time of the low-side switching tube in a steady state before the DC-DC converter triggers inductor overcurrent protection. The LS conduction duration can be controlled after the DC-DC converter triggers overcurrent protection, and the method is simple and easy to implement.

A power input interface protection circuit and a power supply relate to the technical field of power supplies. The circuit comprises a protection module, an anti-reverse connection module and a filtering module. The protection module is used for being connected with an input power supply and protecting working voltage and working current output by the input power supply; the reverse connection prevention module is connected to the overcurrent protection module and is used for disconnecting the connection with the input power supply when the input power supply is reversely connected with the protection module; and the filtering module is connected to the anti-reverse-connection module and is used for filtering the working voltage and the working current output by the input power supply and outputting the working voltage and the working current so as to supply power to a load connected with the filtering module.

The application relates to a circuit for improving the safety of a secondary lithium battery, which comprises a lithium battery body, characterized in that: an auxiliary circuit and an overcurrent protection wire harness are further included; the auxiliary circuit is connected in parallel between the positive and negative output ends of the lithium battery body, the auxiliary circuit comprises a temperature monitoring element and an alarm module connected in series; the temperature monitoring element is used for turning on the auxiliary circuit to make the alarm module electrify and operate when the cell temperature of the lithium battery body rises to an alarm temperature; the alarm module is used for issuing an alarm to remind the staff that the lithium battery body is over-temperature or controlling the charging loop of the lithium battery body to be disconnected; the overcurrent protection wire harness is connected in series on the power loop of the lithium battery group, and the overcurrent protection wire harness is used for cutting off the loop when external short circuit occurs. The scheme solves the problem that the cycle life of the secondary lithium battery group is wasted by the control panel detecting the cell state.

An overcurrent protection circuit that limits a current to be monitored based on a current limit signal includes: a first transistor and a second transistor configured to form an amplifier input stage that receives input of a detection signal according to the current to be monitored; a third transistor configured to generate a current output signal according to a difference between the detection signal and a reference signal, and configured to form an amplifier output stage that inputs the current output signal as a negative feedback to the amplifier input stage; and a current mirror circuit configured to generate the current limit signal by replicating a signal based on the current output signal.

The utility model discloses a power distribution terminal battery management box capable of quickly replacing batteries. The power distribution terminal battery management box comprises an outer box, an inner box, a protection module and a driving module, the outer box comprises a cover plate, a first connecting hole, a second connecting hole, a sliding rail and a pulley; the inner box comprises an inner box handle and a battery mounting box; the protection module comprises an overcurrent protection module, an overheating protection module and a switch; the driving module comprises a driving handle, a connecting rod, a pressing plate and positive and negative electrode contact points; the positive and negative contact points are electrically connected with a wiring terminal, and the wiring terminal passes through the protection module and then leads out a pair of positive and negative power lines to the outside of the outer box; the device adopts a modular wiring structure, can be matched with a power distribution terminal battery for use, improves the working efficiency of on-site battery replacement, reduces short circuit hidden dangers caused by complex battery wiring and the like, and effectively guarantees personal and power grid safety.

A motor overcurrent protection circuit relates to the field of pan-tilt control, and when a pan-tilt motor is overloaded or stalled, the current flowing through a resistor I in the circuit is increased, the voltage drop on the resistor I is increased accordingly, the voltage at the positive input end of a voltage comparator is greater than the voltage at the negative input end of the voltage comparator, the voltage comparator outputs a high level, and a triode is conducted to conduct a PMOS tube. The alarm unit sends out alarm information to remind workers of timely processing. And if the field staff does not arrive, the voltage output by the output end of the voltage comparator triggers the control electrode of the thyristor, the thyristor is conducted, the power supply circuit of the pan-tilt motor is cut off, and the pan-tilt motor stops rotating. The internal circuit of the pan-tilt motor is effectively prevented from being burnt, and the service life of the pan-tilt is prolonged.

The invention discloses a self-locking circuit for a low-voltage power supply and distribution system, which integrates the functions of starting, self-locking keeping, overcurrent protection, state indication and resetting, is completely composed of analog and digital hardware electronic components, does not need to be controlled by any software program, and is simple in structure and convenient to use. The method is suitable for industrial automation, safety equipment power supply and other scenes with high reliability requirements.

This application provides a power element protection circuit, including: a current change rate detection module, a boost module, and a drive module. The drive module has a protection terminal and a drive terminal. The current change rate detection module is configured to send a first trigger signal to the boost module when it detects that the rate of change of current flowing through the power element is greater than or equal to a preset threshold for a continuous preset duration. The boost module is configured to increase the voltage at the protection terminal of the drive module to a preset voltage when it receives the first trigger signal. The drive module is configured to output a shutdown signal to the control terminal of the power element through the drive terminal to shut down the power element when the voltage at the protection terminal increases to the preset voltage. Applying the technical solution of this application can solve the problem in related technologies where detecting the voltage of the power element to determine whether a short circuit has occurred leads to the overcurrent protection function of the drive module being easily falsely triggered.

The invention discloses a sampling overcurrent protection system and method. The system comprises a sampling module, a BMS, a switching element, a PPTC assembly and a voltage dividing module. A battery cell in the battery module is connected with the sampling module through the switch piece, the PPTC assembly and the voltage division module, the sampling module is in communication connection with the BMS, and the sampling module is configured to collect a first voltage signal of the battery cell and send the first voltage signal to the BMS; the first end of the voltage dividing module is connected with the sampling module, the second end of the voltage dividing module is also connected with the sampling module, the sampling module is configured to collect a second voltage signal of the voltage dividing module and send the second voltage signal to the BMS, the switch piece is in communication connection with the BMS, and the BMS is configured to cut off connection between the battery cell and the sampling module through the switch piece according to the second voltage signal. When the electrical core is short-circuited, the resistance value of the PPTC assembly is increased instantly, so that the current is limited, overcurrent protection is realized, the electrical core is not short-circuited any more, the resistance value of the PPTC assembly returns to normal, and the sampling loop works normally.

The present disclosure provides a voltage conversion circuit and a voltage conversion chip. A problem that an overcurrent protection signal is falsely triggered can be solved by connecting a first diode in series between an output terminal and an input terminal of a voltage conversion module. The present disclosure provides the voltage conversion chip. A negative voltage capability of an output pin of the voltage conversion chip is increased by setting a comparator and a constant voltage source.

The invention discloses a master control system with a fault recovery function, a control method and equipment, mainly relates to the technical field of fault recovery, and is used for solving the problems that in the existing scheme, a master control automatic restart mode cannot thoroughly power off the master control system and peripheral equipment, the cost of a mode of adding a 4G switch module is high, and self-recovery of the master control system cannot be realized. Comprising an anti-reverse and over-current protection assembly connected to a direct current power supply, an LDO voltage reduction assembly connected with the anti-reverse and over-current protection assembly, a power switch, an MCU system assembly connected with the LDO voltage reduction assembly, a drive circuit connected with the MCU system assembly and the power switch, and a host system connected with the MCU system assembly and the power switch. And the host system is connected with peripheral equipment.

The invention discloses a resonant circuit overcurrent protection system and method in the technical field of resonant circuit overcurrent protection, a resonant circuit is connected with a current sampling circuit and a driving circuit, and the system comprises an overcurrent protection module used for detecting an overcurrent event of the resonant circuit. The control module is used for carrying out PWM (Pulse-Width Modulation) wave sealing in a dead zone after the resonance circuit is over-current; the over-current protection module comprises an over-current detection circuit, an over-current signal holding and resetting circuit and a primary over-current protection circuit. According to the invention, the overcurrent detection circuit is adopted to detect an overcurrent event, based on an overcurrent signal, the reset circuit cooperates with the first-stage overcurrent protection circuit, precise control of PWM wave sealing is carried out in a dead zone, after the overcurrent event is detected, the overcurrent signal is locked, and the turn-off operation is carried out after waiting for the dead zone moment, so that a switching tube is always turned off near a current minimum value, and thus the power consumption is reduced. The turn-off voltage stress is obviously reduced, a switching tube with lower withstand voltage is allowed to be selected, and the cost is reduced.

The invention belongs to the technical field of aircraft control, and particularly discloses an airborne power supply control system and method, and the method comprises the steps: a protection circuit achieves the power supply overcurrent protection, surge current suppression protection and surge voltage protection of an input aircraft power supply, and transmits the power supply overcurrent protection, surge current suppression protection and surge voltage protection to a filter circuit; the filter circuit carries out electromagnetic interference filtering on the input airplane power supply and sends the electromagnetic interference to the power supply interruption detection circuit, the power supply control circuit and the energy storage circuit respectively; when the power supply of the aircraft is cut off instantaneously, the energy storage circuit continues to supply power to the flight control equipment to enable the flight control equipment to work normally. The power supply interruption detection circuit detects the working state of an aircraft power supply in real time, and sends power supply interruption information to the flight control equipment when detecting that the aircraft power supply has power supply transient interruption; and after receiving the power supply interruption information, the flight control equipment controls the power supply control circuit to cut off the power supply of the aircraft power supply to other equipment, and controls the aircraft power supply to supply power to other equipment again after a preset time is delayed.

The invention relates to the field of valves, in particular to an intelligent valve of a 4-20 mA acquisition transmitter powered by a power source and a control method. The intelligent valve comprises a valve body, an execution mechanism, a power supply module, two paths of 4-20mA signal acquisition modules, a temperature sensor module, a control module and a data transmission module. The power supply module provides stable power for the system; the two signal acquisition modules are independently connected with an external transmitter respectively, and each signal acquisition module comprises an overvoltage and overcurrent protection unit, a current-voltage conversion unit and an impedance conversion unit; the temperature sensor module collects the pipeline temperature in real time; the control module coordinates work of all the modules, processes collected signals, communicates with a control center through the data transmission module, and accurately controls an executing mechanism to adjust the opening degree of the valve according to data or instructions. According to the invention, through the highly integrated signal acquisition and processing unit, synchronous accurate acquisition of multi-path key parameters of a heat supply pipe network and intelligent valve regulation and control are realized, and the technical problem of difficult accurate regulation and control of unfavorable points of a heat supply system is effectively solved.

The invention relates to the technical field of electrical control and circuit protection, and discloses an anti-overcurrent building controller which comprises a protection mechanism, a sealing mechanism is arranged on the front face of the protection mechanism, a control mechanism is arranged at the bottom of the protection mechanism, and the outer side of the control mechanism is fixedly connected with the interior of the protection mechanism. And the outer side of the sealing mechanism is inserted into the protection mechanism. According to the building controller with the anti-overcurrent design, the reliability and redundancy of overcurrent protection are improved, when a certain resettable fuse breaks down, other resettable fuses can still work normally, accurate protection of a circuit is achieved, damage to the service life of the circuit is reduced, early warning information is sent to a monitoring center and wireless communication equipment through the controller, and the safety of the monitoring center and the wireless communication equipment is improved. And the safety of the equipment is remotely processed, so that a worker can conveniently manage a plurality of building controllers in a centralized manner, know the operation state of the equipment in real time and perform unified scheduling and management, and maintenance personnel do not need to run around to check the situation.

A frequency-independent phasor calculation method suitable for pumped storage unit protection, the electrical quantity of the pumped storage unit is sampled to form electrical quantity sampling values; the response signal corresponding to the time domain signal of the electrical quantity sampling values is obtained by using Hilbert transform, the data window length in the Hilbert transform is determined by using the lower limit of the frequency range to be protected during the starting of the pumped storage unit, and the amplitude and phase of the electrical quantity are determined by using the time domain signal and the response signal; the over-current protection phasor and the negative sequence protection phasor are calculated by using the electrical quantity. The method provided by the application only needs to select a fixed data window according to the lower limit of the frequency, greatly improves the response speed, has higher calculation accuracy without frequency measurement, and has stronger noise and higher harmonic resistance.