196results about How to "Improve homeostasis" patented technology

A gate drive circuit includes a turn-on side circuit for turning on a gate of a power switching device, the turn-on side circuit including a first turn-on side power supply circuit and a second turn-on side power supply circuit, the first turn-on side power supply circuit including: a first turn-on voltage source for supplying a first turn-on voltage; first turn-on wiring; and a first turn-on switch connected in the first turn-on wiring and controlled by a gate drive signal; and the second turn-on side power supply circuit including: a second turn-on voltage source for supplying a second turn-on voltage applied to the gate of the power switching device to set the power switching device in a steady (on) state; second turn-on wiring; a second turn-on switch connected in the second turn-on wiring; and a turn-on side delay circuit for delaying the gate drive signal and passing it to the second turn-on switch.

The invention discloses an automatic regulating apparatus for controller parameters of a servo driver of a motor and a method thereof. The apparatus comprises an inertia identifier, a parameter initial regulator, a parameter checker, a parameter optimizer, a parameter saving and displaying device, a speed controller, a position controller, a torque controller, a PWM (Pulse-Width Modulation) generator and a coded disc. In the invention, the servo driver of an alternating current permanent magnet motor automatically configures the parameters of the position controller and the speed controller according to different rotary inertias of mechanic load, checks and further optimizes the automatically configured parameters through the parameter checker and the parameter optimizer so that the position response and the speed response of the servo driver are relatively optimal. The servo driver of the alternating current permanent magnet synchronous motor automatically regulates the control parameters according to work occasions and achieves ideal control effect. The whole process is manual participation free and completed fully by the servo motor of the alternating current permanent magnet synchronous motor.

The invention discloses an asymmetric direct power control method of grid-connected three-phase Voltage Source Converter (VSC). Instantaneous active and reactive powers of VSC inputted from electricity grid are calculated by collecting three-phase network voltage and input current signals of the VSC, and the error signal between the instantaneous active and reactive powers and given active and reactive powers is adjusted by using a proportional resonance adjuster; the output signal of the adjuster obtains the VSC output reference voltage signal of synchronous rotary coordinate system after feedback compensation decoupling, and a switch signal controlling VSC operation condition is produced after spatial vector pulse-with modulation. The method in the invention can eliminate double frequency wave motion of direct-current busbar voltage and instantaneous reactive power due to asymmetric electricity grid voltage without decomposition of positive-negative sequence component, thereby avoiding incoming decomposition delay and error, and thus being capable of improving dynamic response and stable operation ability of VSC in the condition of asymmetric electricity grid failure.

The invention provides an Enterococcus faecium ANSE228 of which the collection number is CGMCC No.4082. The invention also provides application of the Enterococcus faecium ANSE228 to inhibition of salmonella pullorum and / or Escherichia coli and / or Staphylococcus aureus. The Enterococcus faecium ANSE228 is obtained by processes of repeated separation, purification, rejuvenation and the like, and has high biological activity, obvious probiotic property, high adversity resistance and the like. The invention also provides a microecological agent which contains the Enterococcus faecium ANSE228. When the microecological agent is added into drinking water and / or feeds for breeding animals, the Enterococcus faecium ANSE228 can be quickly activated and reproduced and a dominant beneficial flora can be formed after the Enterococcus faecium ANSE228 is fed into intestinal canals of the animals, and the Enterococcus faecium ANSE228 has the effects of reducing a harmful flora in the intestinal canals, adjusting microecological balance of the intestinal canals, substituting for medicaments such as antibiotic and the like, and improving weight increment of the animals and the utilization rate of the feeds.

The invention discloses a robust fault tolerance method of a sensor fault of a flow control system of an aircraft electric fuel pump. A rotating speed instruction adjustment part and a rotating speedcontrol part are arranged. The rotating speed instruction adjustment part provides a proper electric fuel pump rotating speed instruction suitable for an all flow range for the control system based onan engine fuel demand instruction, a fuel flow non-linear steady-state model and an output fuel flow of an electric fuel pump. The rotating speed control part is mainly used for minimizing an error between an actual rotating speed and a rotating speed instruction; and under the circumstance that the uncertainty and the sensor failure are considered, on the basis of an adaptive combined nonlineardynamic model of the electric fuel pump, a sliding mode fault estimator and a sliding mode rotating speed controller are designed comprehensively based on a sliding mode theory, so that the rotating speed response of the electric fuel pump is done quickly and the expected rotating speed is reached accurately; and thus on-demand oil supply for the aero-engine by the electric fuel pump is realized safely, reliably, quickly, and precisely.

The invention discloses a sine wave inverter parallel system with variable current ratio, which is characterized by comprising a monitoring management unit and one or a plurality of inverter power supply modules in redundancy parallel operation; the monitoring management unit is connected with all the inverter power supply modules through a communication signal wire; the inverter power supply modules are mutually connected by the communication signal wires, synchronous signal wires and average current signal wires; and each inverter power supply module is simultaneously connected with a DC (Direct Current) input end and an AC (Alternating Current) output end. The proportion of the load current shared by each module of the parallel system provided by the invention can be set as required so as to meet the requirements on uniform load current sharing (current equalization) by parallel inverter power supply modules with same capacity or load current sharing by the inverter power supply modules with different capacities in the parallel system according to different proportions, so that the parallel function of the inverter power supply modules with different capacities is realized.

The invention discloses a bidirectional direct-current converter feedback linearized back-stepping sliding-mode control mode. The bidirectional direct-current converter feedback linearized back-stepping sliding-mode control method comprises steps of using a filtering capacitance voltage and inductive current as control variables to establish a mathematic model of a bidirectional direct-current converter, performing feedback linearization on an original state variable to form a new linearized state equation, tracking an error with a new state variable as an input of a controller, combining a back-stepping method with a sliding-mode variable structure and designing a feedback control rule of a converter system, wherein the feedback control rule of the inverter system is performed on pulse width modulation and controls the bidirectional direct-current converter. The bidirectional direct-current converter feedback linearized back-stepping sliding-mode control mode combines the feedback linearization with the back-stepping sliding mode control to apply to the bidirectional direct-current converter, solves a non-minimum phase characteristic and a variable structure characteristic of the converter, greatly reduces fluctuation of bus voltage, expands a stable area of a system and has a good engineering application prospect.

The invention relates to a control method for a photovoltaic grid-connected inverter on the basis of back-stepping sliding-mode control. The control method is technically characterized in that direct current voltage Udc of a photovoltaic side bus is collected, a mathematical model of a photovoltaic grid-connected single-phase voltage full-bridge inverter is set up, a tracking error of a control variable uac is set, a back-stepping sliding-mode control model of the photovoltaic grid-connected single-phase voltage full-bridge inverter is set up, and the single-phase photovoltaic grid-connected inverter is controlled according to the mathematical model and the back-stepping sliding-mode control model of the photovoltaic grid-connected single-phase voltage full-bridge inverter. The control method is reasonable in design, a back-stepping method and a sliding-mode control method are combined, the stable state and the dynamic property are good, and the control method is suitable for linear and non-linear loads and adapts to engineering application reality, provides a new thought for the inverter control system design and has the good engineering application prospect.

An exhaust aftertreatment device for an internal combustion engine is disclosed which contains multiple, parallel channels of a porous material, such as cordierite or silicon carbide, in which about some of the channels are plugged at an upstream end and other channels remain unplugged. In one embodiment, the substrate has an SCR coating and the engine has a urea supply system. Other embodiments include using TWC and LNT formulations. Several washcoat configurations and other specific geometries and dimensions to encourage crossflow, diffusion, and adsorption are disclosed herein.

The invention provides newly-separated Lactobacillus plantarum HEW-A490. The Lactobacillus plantarum HEW-A490 has the advantages that the Lactobacillus plantarum HEW-A490 is evident in probiotic performance and stress resistance, the probiotics prepared by the Lactobacillus plantarum HEW-A490 can fast activate and proliferate after entering the intestines of animals and can form a beneficial dominant bacterial community to maintain intestinal track balance, animal feed utilization efficiency can be increased, cost can be saved, the steady state of the digestive tract internal environments in the animals is improved, nutrition absorption is promoted, animal growth is promoted, economic benefits are increased, the Lactobacillus plantarum HEW-A490 is promising in application prospect, and the like.

The invention provides an excitation control device of a brushless doubly-fed motor independent power generation system and belongs to a power generation control device for a brushless doubly-fed motor. According to the technical scheme of the invention, the defects in the prior art that, an existing scalar control method is poor in dynamic performance and a conventional bisynchronous rotating reference frame is complicated in vector control, high in cost and low in efficiency can be overcome. According to the technical scheme of the invention, the device comprises a PW voltage magnitude controller, a PW voltage frequency controller, a CW current vector controller, an LC filter, a rotating speed calculator, a CW current frequency feed-forward amount calculator, a PW voltage phase-locked loop and a PW current converter. The CW current vector controller of a brushless doubly-fed motor is adopted as an inner ring, while the PW voltage magnitude controller and the PW voltage frequency controller of the brushless doubly-fed motor are adopted as an outer ring. In this way, the PW voltage magnitude and the PW voltage frequency are independently controlled. Meanwhile, a cross feed-forward compensation mechanism is adopted in the CW current vector controller, so that the device is faster in response rate and better in stability precision. The constant-frequency and constant-voltage generating function of the brushless doubly-fed motor independent power generation system in the speed-varying and load-varying condition is realized.

The invention discloses enterococcus faecalis HEW-A131 which is high in thermal resistance, wide in acid-alkali resistance range, high in stress resistance and relatively high in probiotic property. The strain is preserved in the China General Microbiological Culture Collection Center on June 17th, 2014, the preservation serial number is CGMCC NO.9353, and the classification name is enterococcus faecalis. The enterococcus faecalis HEW-A131 has excellent microorganism characteristics, remarkable probiotic property and stress resistance and super high fermentation property, not only is the utilization efficiency of feed of animals increased, but also the cost is reduced, moreover the stability of the environment inside the alimentary canals of animals is greatly improved, the adsorption and utilization of nutrition are promoted, the animal growth is promoted, the production performance, immunity and breeding property of the animals are remarkably improved, the production cost is lowered, and the economic benefits are increased.

The invention relates to a real-time monitoring method for short-circuit current of a near zone of a transformer, and the real-time monitoring method is characterized in that three non-inductive resistors connected in series onto three current transformators at the secondary side of the transformer are used for sending acquired analog signals to an analog / digital (A / D) sampling unit through an isolation amplifier, a low-pass filter, an absolute converting unit and a range self-adaption unit; the A / D sampling unit is used for continuously acquiring the analog signals; a first processor is used for computing read current sampled data, screening to obtain a wavelike current effective value and the fault instantaneous value of break-variable of current and caching fault data at the fault occurrence moment to a dual ported memory; a second processor is used for receiving the fault data of the dual ported memory and communicates with an upper computer through a network interface to draw an oscillogram, and simultaneously, the second processor is used for performing statistics on the received fault data and storing to a large-capacity memory. According to the real-time monitoring method for the short-circuit current of the near zone of the transformer, acquisition, recording and analysis are performed on the short-circuit impact current at the secondary side of the transformer, and an accurate basis can be provided for the running state analysis and the maintenance of the transformer.

The invention discloses a permanent-magnet synchronous-motor open-winding fault-tolerant direct torque control method based on improved SVPWM. The method comprises the following steps of when an inverter switch tube has an open circuit fault, cutting off connection between a motor port and the fault inverter switch tube, connecting the motor port to a power supply midpoint, and using the remainingswitch tube to carry out fault-tolerant reconstruction on a system topology; through a PI controller, outputting a given torque; using a ''current method'' to estimate a stator flux linkage; and through the difference value of the given torque and an estimated torque, acquiring the variable quantity d delta of a load angle, using a maximum torque current ratio control method to give a reference stator flux linkage, and based on that, calculating a given reference voltage vector. Through the remaining switch tube, improved spatial voltage vector pulse width modulation reconstruction is performed. A double-inverter PWM control signal with a fixed switch frequency is output to an inverter. Under the open circuit fault of the switch tube, the safe and stable operation of a system under the fault is guaranteed, and the system has a good stable state and dynamic performance.

The invention discloses a chicken feed probiotic agent containing enterococcus faecalis and a preparation method of the chicken feed probiotic agent. The chicken feed probiotic agent is prepared by virtue of the steps of evenly mixing enterococcus faecalis HEW-A131 active bacterial sludge, bacillus subtilis active bacterial sludge, saccharomyces cerevisiae active bacterial sludge and a stabilization protective agent together in the mass ratio of (0.1-0.8): (1-2.5): (0.1-0.5): 1, and then pelletizing, drying, coating and the like; the probiotic agent is capable of improving the utilization efficiency of an animal feed and saving the cost, and also capable of greatly improving the steady state of the internal environment of the digestive tract in an animal body, promoting the absorption and utilization of nutrition and promoting the growth of the animal; as a result, the productivity, the immune performance and the reproductive performance of the animal are obviously improved, the production cost is reduced and the economic benefit is increased.

The invention belongs to the technical field of droop control of DC converters, relates to a droop control method of a DC converter with a function of secondary adjustment of adaptive impedance, and aims to solve the problems that distributed generating unit cable impedance difference causes poor droop current homogenization effect to the DC distributed power supply system and the DC micro grid based on droop control and the parallel DC converters is low in steady state and dynamic current homogenization precision. The method has the advantages that the steady state and dynamic current homogenization precision of the parallel DC converters in the distributed DC power supply system and the DC micro grid based on droop control is improved; parameters, such as voltage, current and droop coefficient, of the parallel converters are transmitted in real time through low-speed communication, the droop coefficient is adjusted in self-controllers of the parallel converters, and finally external characteristic impedances of the parallel converters are equalized; droop curves are subjected to shifting adjustment, and bus voltage drop caused by droop control is improved.

This invention relates to a 2-way DC convertor by phase shift of voltage regulation at one end and current stabilizing at the other plus PWM control and a control method, in which the 2-way DC converter includes a primary circuit, a switch control and a close-ring control, the primary circuit is composed of inductor L1, a switch tube S1 and serial branch 1, inductor L2, switch tube S2 and serial branch2, two auxiliary switch tubes Sa1 and Sa2, a clamp capacitor Cc and a composite branch 3, switch tubes S3 and S4 and serial branch 4, bleeder capacitor Ca and Cb, a serial branch 5 and an isolation transformer, the switch control circuit is composed of a phase shift control chip, a monostable trigger8 and a PWM control chip 9, the close ring control part is made up of a phase shift angle close ring control loop and a duty ratio close ring control loop, characterizing that: 1, suppressing the voltage peak of the tube, 2, reducing the circumfluence loss of the converter to guarantee the soft switch in the total load sphere, 3, the uncoupling control of the phase shift angle and the duty ratio realizes 2-way free flow of energies.

The invention discloses an active noise reduction headphone based on an active noise control algorithm, a noise reduction method and a storage medium. The method comprises the following steps: acquiring headphone outside noise by a reference microphone, and transmitting the acquired outside noise to all active noise control systems; processing the outside noise acquired by the reference microphoneby the active noise control systems by virtue of a variable order algorithm of combining a variable iteration parameter and a qualified function, and outputting cancellation noise to a silencing speaker; and outputting the received cancellation noise by the silencing speaker and canceling the actual noise. According to the novel active noise reduction headphone based on the active noise control algorithm provided by the invention, with the adoption of a robust design, the noise signal is subjected to cyclic iterative processing by the system, the most suitable noise reduction system parameters can be selected, and the change of a noise signal is rapidly and accurately tracked, so that the noise reduction effect is greatly improved.

The invention belongs to a motor drive controller, and particularly discloses a tri-redundancy brushless DC servo drive controller which comprises three servo control driver circuits, wherein the servo control driver circuits are connected in parallel, are respectively communicated with a brushless DC motor, and communicate with one another; each servo control driver circuit comprises a servo control module, a motor driver module, a current detection module and a potentiometer; the output end of each servo control module is communicated with the input end of the corresponding motor driver module; the output end of each motor driver module is communicated with a three-phase winding output end of the brushless DC motor; the input end of each current detection module is communicated with a detection signal output end of the brushless DC motor; the output end of each current detection module is communicated with the input end of the corresponding servo control module; the input end of each potentiometer is communicated with a position signal output end of the brushless DC motor; the output end of each potentiometer is communicated with the digital signal input end of the corresponding servo control module. Through the adoption of the tri-redundancy brushless DC servo drive controller, high integration and redundancy design of electromechanical servo control can be realized.

The invention discloses a maximal power point tracking (MPPT) control method for a single-phase single-stage photovoltaic inverter. The method comprises the steps of: sampling output current and output voltage of a photovoltaic cell, calculating output power of the photovoltaic cell; respectively filtering direct current components of the output voltage and the output power through high-pass filtering to obtain alternating current components of the output voltage and the output power; regarding the alternating current component of the output voltage as disturbance quantity of optimizing control of an extreme value, multiplying the disturbance quantity by the alternating current component of the output power, and then obtaining estimated work voltage of the maximal power output point by low-pass filtering and integration, superposing the disturbance quantity on the estimated work voltage, and repeatedly carrying out the steps to ensure that the photovoltaic cell works near the maximal power output point all the time. According to the maximal power point tracking control method for the single-phase single-stage photovoltaic inverter disclosed by the invention, the inherent quality of the system is sufficiently utilized without additionally injecting a disturbance signal, and the effect of the external disturbance signal on the system is eliminated. In addition, the maximal power point tracking control method for the single-phase single-stage photovoltaic inverter can ensure less calculation of the MPPT control method, thereby facilitating implementation.

The invention discloses a least square method-based extended Kalman filter rotating speed estimation method of an asynchronous motor. The method is specifically implemented according to the following steps of (1) solving a fading factor by use of a least square method, obtaining an optimized fading factor determining algorithm, adaptively adjusting an estimation error in real time and quickly tracking a state change; (2) introducing the fading factor into a state prediction covariance matrix of a traditional extended Kalman filter, building a strong tracking extended kalman filter, adjusting a gain matrix online in real time and compelling output residual sequences to be kept mutually orthogonal; and (3) building the least square method-based strong tracking extended kalman filter digitization system under an alpha-beta shaft system of an induction motor and carrying out rotating speed estimation. By the rotating speed estimation method disclosed by the invention, the adaptability of a system model on an actual system and an external environment change is improved; the steady accuracy and the gross error resistance of the system are improved and the system is faster in convergence in a disturbance.

The invention discloses a Buck-Boost converter variable damping passive control method based on a port controlled dissipation Hamiltonian model. The method comprises the following steps of 1, according to the system state averaging model and the state variables of a Buck-Boost converter, converting the system state averaging model of the Buck-Boost converter into a port controlled dissipation Hamiltonian model form, and verifying the passivity of the port controlled dissipation Hamiltonian model form; 2, according to the port controlled dissipation Hamiltonian model of the Buck-Boost converterand an interconnection and damping distribution passive control method, giving an expected interconnection and damping matrix and carrying out passive controller design; 3, designing a second-order differential tracker according to the influence of the damping coefficient change of the given damping matrix on the system performance, and realizing the real-time change of the injection damping; 4,designing a variable-damping passive controller according to the passive controller and the second-order differential tracker, and controlling the output voltage of the Buck-Boost converter. Accordingto the invention, by means of the control method, the output voltage of the Buck-Boost converter can be quickly converged to the expected output voltage. The steady-state error of the output voltageis reduced, and the overall performance of the system is improved.

The invention discloses a network access current control method for a single-phase less container load (LCL) filtering grid-connected inverter and belongs to the field of network access current control of a grid-connected inverter. The method comprises the following steps of: feeding back six voltage and current variables which are easily measured in a single-phase LCL filter to obtain 18 feedbacks through proportion, integration and differential, and selecting a proper feedback combination to configure a characteristic equation of an LCL filter grid-connected inverter system transfer function from a third order to a fourth order so as to guarantee that four poles of the configured characteristic equation can be freely configured; further configuring a fourth-order characteristic equationin a form that two poles serve as conjugate poles at fundamental frequency and two poles serve as conjugate poles at resonant frequency; and finally, comparing to acquire various feedback coefficients in the selected feedback combination. By the method, the high gain of a system open loop transfer function on a forward path is achieved, a resonance peak at a natural resonant frequency is effectively suppressed, and the system has good steady state and dynamic responses.

The invention discloses a magnetic isolation drive circuit comprising an isolation drive transformer, a first capacitor C1, a second capacitor C2, a discharge MOS pipe and a discharge MOS pipe drive circuit, wherein the isolation drive transformer is used for transmitting an isolation drive signal; the first capacitor C1 is connected with the input side of the isolation drive transformer in series; the second capacitor C2 is connected with the output side of the isolation drive transformer in series; the discharge MOS pipe is connected with the output end of the magnetic isolation drive circuit in parallel; the discharge MOS pipe drive circuit is connected to a grid electrode of the discharge MOS pipe; and a series loop is formed by an output side winding of the isolation drive transformer, the second capacitor C2 and the discharge MOS pipe. The magnetic isolation drive circuit has simple structure and low cost and can effectively increase the stability of a power supply which works in a stable state and a transient state.

The invention discloses a model prediction current control method of a permanent magnet synchronous motor. The method comprises the following steps: obtaining a d-axis current disturbance item and a q-axis current disturbance item; obtaining three-phase current, three-phase line voltage and rotating speed signals of a permanent magnet synchronous motor, and obtaining a d-axis current observation value, a q-axis current observation value, a d-axis current disturbance item observation value and a q-axis current disturbance item observation value by utilizing a linear expansion state observer; obtaining a d-axis output value and a q-axis output value of a disturbance controller, obtaining an inductance prediction value by using an inductance extraction algorithm, and obtaining a d-axis current prediction value and a q-axis prediction current value in combination with an incremental prediction model; and adjusting the switching signal of the permanent magnet synchronous motor by using theinductance prediction value, the d-axis current prediction value and the q-axis prediction current value so as to realize the closed-loop control of the permanent magnet synchronous motor, so that therobustness of a permanent magnet synchronous motor model prediction current control algorithm is improved.

The invention discloses a three-phase synchronization method based on a wireless mode, and the method comprises the steps that three phases of a power system receive the time tick signals and store the respective sampling point position information and system time information at the same time; the three phases respectively calculate the sampling point position difference values and the system timedifference values; any one phase transmits its sampling point position difference value and system time difference value to the remaining two phases; the remaining two phases carry out the sampling point position synchronization and system time synchronization according to the received sampling point position difference value. The method improves the steady and transient precision of the zero-sequence current and zero-sequence voltage after three-phase overlapping. The method greatly increases the time tick period of a gathering unit, facilitates the reduction of the operation power consumption of the system, and improves the time tick redundancy of the gathering unit and the stability of the system. The method provides a reliable guarantee for the fault recording through improving the three-phase synchronization precision and the stability of the system.

The invention provides newly separated enterococcus faecium (enterococcus faecium) HEW-A588. The enterococcus faecium HEW-A588 has obvious probiotic and stress resistance. When the micro-ecologic preparation prepared from the enterococcus faecium enters intestinal tracts of animals, the micro-ecologic preparation is rapidly activated and proliferated, the micro-ecologic preparation can have the efficacies of forming beneficial advantage microbial populations, maintaining the balance of the intestinal tracts, improving the food utilization efficiency of the animals, reducing the cost, improving the steady state of the internal environment of the digestive tracts in the animal bodies, promoting the absorption and the utilization of nutrition, promoting the growth of the animals, improving economic benefits and the like, and the micro-ecologic preparation has favorable application prospects.

The invention discloses an unbalanced power adaptive optimization allocation method for a multi-end linear system. The method employs a dual-layer control structure comprising a primary sag control layer and a power rebalance optimization layer. The power rebalance optimization layer aims at the unbalance power caused by the frequent fluctuation of a load or new energy, and an equivalent cost expression of a system additional power generation cost caused by the power rebalance is deduced based on a multi-end flexible DC polar coordinate equivalent model comprising a voltage source converter station, a radial multi-end flexible DC common DC reference voltage is introduced, and a novel active power-DC voltage sag curve is designed. The proposed method irons out the defects that the conventional optimization control strongly depends on the high-speed communication and a centralized processing layer. The method can enable the white balance power to be adaptively and economically allocatedunder the normal condition, enables the additional power generation cost of a system to be remarkably reduced, still can maintain the DC voltage stability and power balance under the fault condition,and is remarkable in control effect.

The invention relates to a repulsion-type electromagnetic displacement actuator, adopting a principle of opposite magnets repulsing mutually to make a repulsion-type electromagnetic actuator, making the same pole tips of the magnetic filed generated by fixed helix tube in the actuator after electrified and the magnetic filed of an armature are opposite so as to generate a repulsion force to push the armature to move, balancing compression return spring or other balance return devices, thus primely solving the problem of nonlinear resultant force displacement property, and strengthening its control accuracy and stability. The material of the moving armature is a soft-magnetic material, both realizing excellent property of proportional electromagnet and avoiding the problems of process complexity, reliability reduction and effective travel reduction of the proportional electromagnet, etc. And it remedies the disadvantage of unstability and control difficulty caused by a system composed of ordinary electromagnet and spring.