202 results about "Dual coil" patented technology

The invention relates to the technical field of geophysical exploration equipment, and particularly discloses a double-top umbrella type multi-angle adjustable transient electromagnetic transmitting coil array detection device which comprises a main supporting system, a framework supporting system, a coil system, a multi-angle adjusting mechanism and a rapid storage system. The device has the beneficial effects that accurate adjustment in a continuous angle range is realized, and the adaptability of the device to different exploration environments is improved; a double-coil system design is adopted, so that two typical working modes are realized; in structural design, a double-top umbrella type folding structure is combined with a light-weight material, so that the weight of equipment is reduced. According to the device, conversion of multiple detection modes is achieved, traditional multiple fixed angle devices are replaced, the equipment investment cost is reduced, and the equipment operation efficiency is improved.

The invention relates to a thin motor, a camera and an electronic device, the thin motor comprises a shell, a focusing module and an anti-shake module, and the focusing module comprises a focusing carrier and a focusing power unit. The anti-shake carrier is movably connected with the focusing carrier through the balls, the anti-shake power unit drives the anti-shake carrier to move relative to the focusing carrier, the anti-shake power unit comprises an X-axis power unit and two Y-axis power units, and each Y-axis power unit comprises a Hall integrated circuit. The anti-shake module innovatively adopts single-layer ball connection, so that the height of the motor is reduced, the assembly procedures and the number of components are reduced, the cost is reduced, and the competitiveness is improved. In order to avoid X-axis and Y-axis crosstalk, the Y-axis power unit adopts a double-coil, double-magnet and double-IC design, a Hall integrated circuit is used for measuring the relative distance, the rotation angle is calculated according to the relative distance, current compensation is adjusted, crosstalk is effectively solved, stability and high efficiency of anti-shake are guaranteed, and a clear picture is provided.

The invention discloses a wafer resistivity and surface metal film thickness detection method based on double coils, and the method comprises the steps: integrating a low-frequency inductance coil and a high-frequency inductance coil on a probe, detecting the wafer resistivity and the wafer surface metal film thickness in real time through the low-frequency inductance coil, and detecting an LOD value in real time through the high-frequency inductance coil. Correcting the measured resistivity of the wafer and the thickness of the metal film on the surface of the wafer according to the LOD value, namely, correcting the thickness of the metal film on the surface of the wafer according to the relationship between the resistivity of the wafer and the thickness of the metal film on the surface under different LOD values and the output voltage value of the low-frequency coil, and the resistivity value of the wafer to be detected and the thickness value of the metal film on the surface of the wafer corresponding to the LOD value detected by the current high-frequency coil in real time are obtained.

The invention relates to a gas stove control device with a fault detection function and a gas stove. The gas stove control device comprises a double-coil electromagnetic valve, a driving circuit, a detection circuit, a controller and an alarm. A main coil of the double-coil electromagnetic valve is connected with a thermocouple, a secondary coil of the double-coil electromagnetic valve is connected with the driving circuit, and the driving circuit is used for outputting driving current to the secondary coil; the detection circuit is connected with two ends of the secondary coil and is used for detecting voltages at two ends of the secondary coil; the controller is connected with the drive circuit, the detection circuit and the alarm and used for controlling on-off of the drive circuit and controlling the alarm to give an alarm according to the voltage, fed back by the detection circuit, of the two ends of the secondary coil. According to the invention, various faults such as open circuit, short circuit and turn-to-turn short circuit of the secondary coil are accurately identified based on the voltages at the two ends of the secondary coil, the alarm gives an alarm to remind a user in time when the fault of the secondary coil is detected, the sensitivity and accuracy of fault detection of the secondary coil are high, and the safety performance is high.

The invention relates to the technical field of power fault detection, and mainly relates to a residual voltage detection circuit and a line protection device.The residual voltage detection circuit comprises a sampling circuit and a signal holding circuit, the signal holding circuit adopts double coils and comprises a first coil and a second coil, and a loop where the first coil is located is provided with a first controllable switch tube in series; the first controllable switch tube is connected when the sampling circuit collects residual voltage, a second controllable switch tube is arranged in a loop where the second coil is located in series, the control end of the second controllable switch tube is used for being connected with a feeder terminal, and the signal holding circuit further comprises a residual voltage output branch used for being connected with the feeder terminal. The residual voltage output branch is provided with a first contact of the double coils in series. A sampling circuit is used for obtaining a residual voltage signal generated at the moment of closing of a faulty power grid line, and a signal holding circuit formed by double coils is used for transmitting a sampling signal to a feeder terminal, so that the feeder terminal can still receive the residual voltage signal when the feeder terminal loses power after power supply is recovered.

The invention relates to the technical field of office supplies, in particular to a puncher with a binding function, the puncher comprises a puncher body and a binding mechanism arranged on the front side of the puncher body, the binding mechanism comprises a lifting support, a magnetic backup plate arranged on the front side of the lifting support and a pressing block arranged on the front side of the magnetic backup plate, and the initial height of the pressing block can be adjusted; the pressing block is parallel to the top face of a base of the puncher body, and a double-coil binding opening is formed between the pressing block and the puncher body. The lifting support can be vertically installed on a fixing support of the puncher body in a sliding mode, the pressing arm of the puncher body is connected with the lifting support through the transmission assembly, when the pressing arm is pressed downwards, the lifting support drives the pressing block to descend, pressure is applied to the double coils in the binding opening so that the double coils can be folded, and binding is completed. When the pressing arm resets upwards, the lifting support drives the pressing block to reset upwards.

The invention relates to the technical field of electric power, in particular to a vacuum circuit breaker and a phase selection closing control method, and the vacuum circuit breaker comprises a hybrid electromagnetic mechanism and a vacuum arc-extinguishing chamber; the hybrid electromagnetic mechanism comprises a permanent magnet closing assembly and an electromagnetic repulsion opening assembly, the permanent magnet closing assembly comprises double coils and a T-shaped movable iron core which are arranged in parallel, and a discharge loop is formed to drive a movable contact of the vacuum arc-extinguishing chamber to complete a closing action and maintain a closing state; the electromagnetic repulsion opening assembly comprises a static coil panel and a moving coil panel which are coaxially and oppositely arranged to form a reverse current repulsion loop so as to drive a moving contact of the vacuum arc-extinguishing chamber to complete an opening action and maintain an opening state, and the moving coil panel is connected with a T-shaped moving iron core of the permanent magnet closing assembly through an insulating guide rod; the vacuum arc-extinguishing chamber comprises a driving connecting rod, a moving contact and a static contact, one end of the driving connecting rod is connected with the moving contact, and the other end of the driving connecting rod is connected with the insulating guide rod. Therefore, the opening and closing speed of the vacuum circuit breaker is improved.

The utility model discloses a double-coil contactor, and the contactor comprises a power module which is used for accessing an external power supply voltage to generate a DC voltage, so as to enable a coil loop to be electrically conducted, and carrying out the voltage reduction of the DC voltage, and obtaining a power supply voltage; the external power supply is an AC power supply or a DC power supply; the sampling comparison module is used for sampling the direct-current voltage and generating a working voltage according to the power supply voltage when the sampling voltage is greater than a preset voltage threshold value; the driving module is used for controlling the pull-in coil loop to be electrically conducted based on the direct current voltage in response to the power supply voltage and the working voltage, and controlling the pull-in coil loop to be electrically disconnected in response to the trigger signal; the time delay module is used for generating a trigger signal when the duration of electrical conduction of the pull-in coil loop reaches a preset duration. According to the double-coil contactor, the AC voltage of the AC power supply can be converted into the DC voltage for control through the power supply module, and the application range of the double-coil contactor is greatly expanded.

The high-pressure-resistant sensor comprises a shell, the shell comprises a body and a cover, a cavity is formed in the body, an opening is formed in one end in the length direction of the body, and the cover is detachably arranged at the opening to seal the shell; the sensing unit is contained in the cavity and comprises a double-coil vibration head module and a signal enhancement module, the double-coil vibration head module comprises a supporting framework, a magnetic tank and a coil assembly, the coil assembly is arranged on the supporting framework and comprises an inner coil and an outer coil which are coaxially arranged, and the diameter of the outer coil is larger than that of the inner coil; the axial directions of the inner coil and the outer coil are consistent with the length direction of the body; the signal enhancement module is coaxially arranged on the periphery of the double-coil vibration head module. According to the invention, the signal penetration capability is stronger, and a thicker metal shell can be penetrated; in addition, the magnetic tank and the coil assembly are wrapped by a strip-shaped amorphous nanocrystalline material with high magnetic permeability, so that the penetrating power of signals is effectively enhanced.

The invention discloses an oil abrasive particle detection device based on pseudo-random signal excitation and an inversion method, a pseudo-random excitation module outputs pseudo-random alternating current excitation formed by combining a plurality of waveforms, and the pseudo-random waveforms are not less than three frequency waveforms; the sensing module is a three-coil balance type, double-coil mutual inductance type or single-coil self-inductance type inductance sensing unit, coils in the sensing module construct a detection area with an alternating magnetic field under the excitation of alternating current, and the alternating magnetic field has pseudo-random characteristics; the signal acquisition and fitting module detects an induced voltage signal of the coil, and signal pulses generated by the metal abrasive particles under different excitation waveforms are obtained through fitting according to pseudo-random alternating current excitation characteristics; and the abrasive particle feature inversion module performs inversion according to the abrasive particle pulse signals generated by fitting under each excitation, and calculates the equivalent radius, the conductivity and the magnetic conductivity corresponding to the abrasive particles, so as to determine the material and the size of the abrasive particles. According to the invention, the material, size and concentration information of the abrasive particles can be accurately obtained.

The invention discloses a chip inductor double-coil implanting machine which comprises a jig disc conveying line, two coil feeding units and an implanting manipulator, each coil feeding unit comprises a feeding vibration disc, a bearing seat, a rotating disc type feeding disc, a longitudinal ejection push rod, a translation receiving disc and a horizontal push rod, and the bearing seat is mounted at an outlet of a straight vibration part of the feeding vibration disc; a first chip groove is formed in the circumference of the feeding disc, m second chip grooves are formed in the upper end face of the side, facing the discharging port station, of the translation receiving disc, and the longitudinal jacking push rod is used for jacking coil products in the receiving groove into the first chip groove of the feeding port station. The horizontal push rod is used for pushing coil products in the first chip groove in the discharging port station into the second chip groove, and the implanting mechanical arm is used for transferring the coil products in the two translation material receiving discs into the jig chip groove in batches. According to the invention, the efficiency of implanting the chip inductance coil into the jig plate can be improved.

The invention relates to a stress loading device and method for amorphous alloy magnetic property measurement, and belongs to the technical field of amorphous alloy magnetic property measurement, and the device comprises the steps: to-be-measured amorphous alloy is placed in a magnet exciting coil, passes through an iron yoke, and is connected with a loading end of an electromagnet loading part; the electromagnet loading part is used for carrying out stress loading on the to-be-tested amorphous alloy from two ends of the to-be-tested amorphous alloy; and the double-H coil is placed in the excitation coil, and the magnetic characteristics of the amorphous alloy are measured by accurately measuring the magnetic flux density and the magnetic field intensity after the pressure is stable. The anti-fracture clamp is made of a polyether-ether-ketone material, is mounted in an inner cavity of the excitation coil and is used for clamping and fixing the amorphous alloy to be detected from the upper side and the lower side of the amorphous alloy to be detected; and the double-H coil is placed in a groove formed in the upper surface of the anti-fracture clamp. The mechanical stress scene borne by the amorphous alloy in actual complex working conditions can be simulated, and an effective solution is practically provided for amorphous alloy magnetic characteristic measurement environments needing to consider mechanical stress factors.

The invention relates to a high-speed switch valve driving electromagnet based on double-coil excitation and a control method thereof.The electromagnet comprises an outer protection assembly, a plug iron, coils, an armature and a movable iron core, the plug iron, the armature and the movable iron core are sequentially arranged on the outer protection assembly from top to bottom, and a set of coils are arranged on the outer side of the plug iron and the outer side of the movable iron core in a surrounding mode; the two groups of coils are respectively used for exciting the armature and the movable iron core, and the lower end of the movable iron core is used for being connected with a high-speed switch valve. Compared with the prior art, the movable iron core and the static iron core can be excited simultaneously, and the response speed of the electromagnet is greatly increased; suction force can be provided when currents of the two coils are in the same direction, release force is provided when the currents are in the reverse direction, and the reset speed of a valve element of the high-speed switch valve is remarkably increased; according to the invention, the actuation frequency of the valve is 1 / 2 of the voltage switching frequency under the condition of no deviation of voltage excitation, so that the upper limit of the working frequency of the high-speed switching valve is greatly improved, and higher-performance control is realized.

The invention relates to the technical field of wind power equipment, in particular to a double-coil electric pulse deicing device for blades of a wind driven generator. The wind driven generator blade comprises a blade body, a cavity is formed in the blade body, the deicing device comprises a deicing controller, a pulse power source and multiple sets of pulse deicing units connected with the pulse power source in parallel, and any set of pulse deicing unit comprises a first pulse coil and a second pulse coil. The first pulse coil and the second pulse coil are fixed in the blade body or on the cavity wall of the cavity, the first pulse coil and the second pulse coil are arranged oppositely, opposite surface gaps exist between the first pulse coil and the second pulse coil, and the multiple sets of pulse deicing units are distributed on the wind driven generator blade at intervals. According to the electric pulse deicing device, an existing electric pulse deicing technology is improved, the structure of the electric pulse deicing device for the wind driven generator blade is simplified, the practicability and safety are improved, meanwhile, the installation cost is reduced, and the purpose of efficient deicing can be achieved while energy is saved.

The application relates to an adaptive double-coil time sequence driving intelligent high-voltage direct-current relay system, which comprises an intelligent power control unit, a double-coil driving unit, a main contact unit, an electric parameter sampling unit, a temperature sampling unit, an arc extinguishing assembly, a communication unit and a soft measurement calculation unit. The double-coil driving unit comprises a starting coil and a maintaining coil; the starting coil realizes rapid attraction of the contact; and the maintaining coil maintains the steady state of the contact. The electric parameter sampling unit collects the main loop current, the contact voltage drop, the coil current and the bus voltage; and the temperature sampling unit collects the coil temperature and the environmental temperature. The soft measurement calculation unit obtains the equivalent temperature of the contact and the vibration intensity. The intelligent power control unit dynamically adjusts the coil power-on duration, the driving voltage and the current, realizes coil time sequence switching, completes contact health assessment, fault prediction and grading protection. The communication unit transmits state, parameter and fault information through a CAN / LIN bus; the arc extinguishing assembly realizes arc extinguishing during disconnection; and the system can reduce power consumption, realize deterioration early warning and effectively avoid device burning.

The invention discloses an array coil excitation coupling eddy current detection probe, system and method and a related device, and relates to the technical field of nondestructive testing. The probe comprises a double-coil excitation module and a sensing module; the double-coil excitation module comprises two semicircular Helmholtz coils; the two semicircular Helmholtz coils are symmetrically arranged, are parallel and coaxial, and are electrified with alternating-current excitation current with the same direction, the same frequency and the same phase; the distance between the two semicircular Helmholtz coils is adjustable; and the sensing module is arranged in the central area of the two semicircular Helmholtz coils and is used for detecting the magnetic field change caused by the eddy current field at the defect. According to the invention, the detection precision of pipeline corrosion, cracks and composite defects can be improved.

Electrical circuitry adapted to drive a dual-coil loudspeaker having a primary voice coil and a second voice coil connected in parallel with the primary voice coil, the second voice coil being in series with an LC resonant circuit of impedance Zmf, further comprising an inductance compensation filter of impedance Zif in parallel with the LC resonant circuit.

The utility model relates to a thin motor, a camera and an electronic device, the thin motor comprises a housing, a focusing module and an anti-shake module, and the focusing module comprises a focusing carrier and a focusing power unit. The anti-shake carrier is movably connected with the focusing carrier through the balls, the anti-shake power unit drives the anti-shake carrier to move relative to the focusing carrier, the anti-shake power unit comprises an X-axis power unit and two Y-axis power units, and each Y-axis power unit comprises a Hall integrated circuit. The anti-shake module innovatively adopts single-layer ball connection, so that the height of the motor is reduced, the assembly procedures and the number of components are reduced, the cost is reduced, and the competitiveness is improved. In order to avoid X-axis and Y-axis crosstalk, the Y-axis power unit adopts a double-coil, double-magnet and double-IC design, a Hall integrated circuit is used for measuring the relative distance, the rotation angle is calculated according to the relative distance, current compensation is adjusted, crosstalk is effectively solved, stability and high efficiency of anti-shake are guaranteed, and a clear picture is provided.

The utility model relates to a contactor auxiliary leading-out sheet and coil skeleton installation structure, comprising a double-coil skeleton which comprises a winding column, and an upper installation plate and a lower installation plate which are respectively formed on the upper side and the lower side of the winding column, one side of the lower installation plate is longitudinally provided with two positioning holes, and a circuit board is provided with connection holes corresponding to the positioning holes; the two auxiliary lead-out sheets are used for connecting the auxiliary lead-out pins and the circuit board, and each auxiliary lead-out sheet comprises an auxiliary lead-out punching sheet and a plastic strip; an assembling groove is formed in the plastic strip, a part of the auxiliary leading-out punching sheet is installed in the assembling groove in a matched mode, and the other part of the auxiliary leading-out punching sheet downwards extends out of the assembling groove and sequentially penetrates through the positioning hole and the connecting hole to be connected in an inserted mode. According to the scheme, the auxiliary leading-out sheet is formed by wrapping the auxiliary leading-out punching sheet and the plastic strip, the structural strength is greatly improved, the auxiliary leading-out sheet is not prone to breakage, meanwhile, the coil framework plays a role in supporting the auxiliary leading-out punching sheet, the positioning hole in the coil framework can be matched with the auxiliary leading-out punching sheet, and the auxiliary leading-out sheet can be prevented from shaking.

The application discloses a double coil for binding, and aims to solve the problem that the existing double coil needs to be opened and closed when disassembling and assembling the pages, and deformation occurs in the opening and closing process, and metal fatigue is caused after a large number of times, so that the double coil cannot be restored to the original state, that is, the double coil cannot be completely closed, and then the normal use is affected.The technical scheme points are as follows: including a double coil body, the double coil body includes a first connecting block, a second connecting block, a plurality of first arc strips fixedly connected to the first connecting block and a plurality of second arc strips fixedly connected to the second connecting block.The application can complete the disassembly and assembly of the pages without moving the first arc strips and the second arc strips, and then the problem that the first arc strips and the second arc strips cannot be closed can be avoided, and the first arc strips and the second arc strips also do not need to be limited by the material type, and the service life of the double coil can be further improved.

The invention provides a wireless electric energy coupling control method based on vehicle pile cooperation, and relates to the technical field of vehicle wireless charging, an electric vehicle wireless power transmission WPT system is of an LCC-S type compensation topological structure, and a DC-DC booster circuit is additionally arranged in front of an output load of the receiving end of the WPT system; the WPT system comprises a first receiver and a second receiver, the first receiver is of a double-pole double-coil structure, the second receiver is of a single-pole double-coil structure, the first receiver and the second receiver are decoupled, and two coils of the first receiver and two coils of the second receiver are arranged diagonally. According to the scheme, an LCC-S type compensation topological structure is improved, a DC-DC booster circuit is additionally arranged in front of an output load of a receiving end, and double-loop control parameters are optimized through a PSO algorithm, so that the charging power of the electric vehicle is stabilized; and the first receiver (double-pole double-coil) and the second receiver (single-pole double-coil) adopt a decoupling structure, and the coils are arranged diagonally, so that the energy transmission efficiency is effectively improved.

The application provides a method for measuring Leeb hardness and Shore hardness based on double-coil electromagnetic induction, which comprises the following steps: placing a to-be-measured object and a magnetized impact body on two sides of two closed coils respectively; the magnetized impact body impacts the surface of the to-be-measured object after passing through the two closed coils at a certain speed; the time interval and the speed of the magnetized impact body when passing through the two closed coils are recorded; and the Leeb hardness or the Shore hardness of the to-be-measured object is calculated. The method for measuring Leeb hardness and Shore hardness based on double-coil electromagnetic induction greatly reduces the error of detection data, and the calculated Leeb hardness and Shore hardness have high accuracy.

The invention discloses a double-coil bone conduction loudspeaker with a hollow design. The double-coil bone conduction loudspeaker comprises a shell (10), a first elastic sheet (5), a second elastic sheet (6), a first iron washer (8), a second iron washer (9), a magnet (7), a first coil (1), a second coil (2), an adapter plate (12), an upper shell (3) and a lower shell (4), the upper shell (3) and the lower shell (4) are arranged on the upper face and the lower face of the outer shell (10) and jointly define an inner containing space. The first coil (1) is fixedly arranged on an internal extension part of the upper shell (3), and the second coil (2) is fixedly arranged on an internal extension part of the lower shell (4). According to the invention, a fully-wrapped double-coil hollow design is adopted, the acoustic sensitivity and the high-frequency anti-howling capability are remarkably improved, and meanwhile, the compatibility of compact structure, efficient vibration conduction and automatic assembly is realized.

A kind of high-density coil-based vibration transducer, the upper part of the transduction structure support is provided with A vibration pickup beam, the lower part of the transduction structure support is fixed B vibration pickup beam, A vibration pickup beam and B vibration pickup beam are provided with permanent magnet, the top cover center of transduction structure support is provided with upper laminated flexible coil, the bottom end center of the shell base below B vibration pickup beam is provided with lower laminated flexible coil;The positive and negative poles of upper laminated flexible coil and lower laminated flexible coil are connected to the electrode sheet of line lead-out terminal in cascaded manner, lead-out terminal is fixed at the center reserved hole of shell top cover, shell top cover and shell base are adapted to form vibration transducer shell together;The present application adopts double-beam plus double-coil output, reduces the transverse vibration of device;Improve device sensitivity, change the previous magnet through-type structure of magnetoelectric transduction structure using winding coil, adopt the upper and lower integrated mode of magnet and coil, effectively reduce the overall size of device.

The invention discloses a water-cooling multi-piece double-coil magneto-rheological brake which comprises a shell assembly, the shell assembly comprises a first shell and a second shell which are symmetrically arranged, annular grooves which are oppositely arranged are formed in the two shells, excitation coils and magnetism isolating rings are installed in the annular grooves from inside to outside, an annular flow channel is formed in each magnetism isolating ring, and the annular flow channels are communicated with the first shell and the second shell; a liquid inlet hole and a liquid outlet hole are formed in the shell, and the annular flow channel of the magnetism isolating ring is matched with the liquid inlet hole and the liquid outlet hole of the shell to form a cooling circulation channel; the multiple brake pads are coaxially arranged between the first shell and the second shell, the brake pads are spaced through shaft sleeves, the brake pads and the first shell as well as the brake pads and the second shell are spaced through shaft sleeves, and gaps are filled with magnetorheological fluid; the rotating shaft penetrates through the center of the shell assembly and the center of the brake pad, and the rotating shaft and the brake pad are coaxially arranged and fixedly connected. Through the design of the double coils, rapid establishment and dissipation of a magnetic field can be achieved, and therefore the braking force can be adjusted more flexibly.

Refrigeration cycle intercooler with dual coil evaporator is a component in a refrigeration cycle that is installed in a vehicle with an internal combustion engine or motor. The refrigeration cycle operates by continuously cycling a refrigerant through a closed loop where refrigerant passes through an inner coil evaporator and an outer coil evaporator where the refrigerant changes from liquid to gas, thereby providing a cooling effect. During operation, fresh air or outside air continuously passes by the inner coil evaporator and the outer coil evaporator and then continues into the internal combustion engine or motor air intake. The inner coil evaporator and the outer coil evaporator function to cool and dry the intake air for the internal combustion engine or motor. The inner coil evaporator and an outer coil evaporator are specially designed to provide substantially more cooling and drying than any other intercooler design.

A double coil guitar pickup assembly includes a first and a second bobbin, wherein each bobbin includes a center section with a hollow interior, a coil wrapped around the center section, a top flange with a diameter greater than a diameter of the center section, and a bottom flange, wherein the top flange has a lateral-facing protrusion and adjacent depression, wherein the first and second bobbins are coupled such that the protrusion of the first bobbin fits securely within the depression of the second bobbin, and such that the protrusion of the second bobbin fits securely within the depression of the first bobbin, and, a cover configured to fit securely over the first and second bobbins, including a pair of fastening orifices configured for fastening the cover to a guitar.

A safe and reliable double-coil contactor control circuit comprises a power supply input end; the starting loop is provided with a starting coil; the holding loop is arranged in parallel with the starting loop and is provided with a holding coil; the auxiliary switch is arranged at the front end of the starting loop, is disconnected when the contactor is attracted, and cuts off the starting loop; and the control assembly is connected in the starting loop in series, the control end of the control assembly is connected with the rear end of the holding loop, and on-off of the starting loop is controlled according to a state signal of the holding loop. Coil dual power supply switching power supply is adopted, a starting coil adopts high-voltage excitation during starting, and low-voltage power supply is adopted in the maintaining process. A signal is provided to the control assembly at the tail end of the holding circuit to control the starting coil, when any element of a holding loop breaks down, excitation high voltage cannot work, fatal faults of a conventional energy-saving circuit are avoided, the problem of unreliable holding caused by catastrophic hazards brought to an electric appliance can be effectively avoided, and primary energy saving is achieved while reliable holding is guaranteed.