Abstract: A rotor production method includes: a first step of arranging a plurality of sintered bodies side by side with an insulating lubricant applied to an interface of at least one of the sintered bodies adjacent to each other, and then housing the sintered bodies in a cavity of a molding die such that the sintered bodies are arranged side by side in the cavity, the sintered bodies being precursors of a plurality of split magnets constituting one rare-earth magnet; a second step of turning the sintered bodies into the split magnets by performing hot working to impart magnetic anisotropy to the sintered bodies arranged in the cavity, and producing an integrated magnet in which the split magnets are integrated together with the lubricant interposed therebetween; and a third step of producing a rotor of a motor by inserting the integrated magnet into a magnet slot of the rotor.

Abstract: A method for manufacturing a rotary electric machine rotor includes forming core block elements; inserting magnets in corresponding one of the magnet holes; forming magnet core blocks by injecting a molten resin into each of the magnet holes from above the magnet, solidifying the molten resin, and thereby forming a resin portion so as to integrate each of the core block elements and the magnets. End surfaces of the magnets are exposed on a first end surface; and the molten resin is injected at a second end surface. The method also includes forming a rotor by stacking and integrating plural magnet core blocks, the plural magnet core blocks being stacked such that first end surfaces of two magnet core blocks that are disposed at both ends in an axial direction constitute end surfaces at both ends of the rotor in the axial direction.

Abstract: Apparatuses and method for manufacturing coil members (230, 250) for insertion in slots of a core of an electric dynamo machine, wherein the coil members (230, 250) are formed by bending portions of an electric conductor (10). Portions of conductor of a predetermined length are fed through an aperture (80), where at least one engagement member (51) can move to engage and bend the conductor (10) so as to form the configuration of the coil member (230, 250).

Abstract: A coil block manufacturing method of winding a wire around a coil core in which a core portion is provided between a first attachment portion and a second attachment portion, includes: a first step of fixing one end of the wire; a second step of, in a state of holding the first attachment portion of the coil core by a first chuck to expose the whole core portion, winding the wire around an end of the core portion; and a third step of, in a state of holding the second attachment portion of the coil core by a second chuck to expose the whole core portion, winding the wire around the whole core portion, to form a coil portion.

Abstract: A vibration motor is provided in the present disclosure. The vibration motor includes a stationary part, a vibration part and an elastic connector. The stationary part includes a housing providing an accommodating space. The vibration part is suspended within the accommodating space by the elastic connector. The stationary part includes a coil, and the vibration part includes a first magnet set and a second magnet set. The first magnet set and the second magnet set are respectively disposed at two opposite sides of the coil for generating a closed magnetic loop. The first magnet set comprises a first left magnet and a first right magnet spaced apart from each other, and the second magnet set comprises a second left magnet and a second right magnet spaced apart from each other.

Abstract: A vibration motor is provided in the present disclosure. The vibration motor includes a housing providing an accommodating space, a magnet assembly accommodated within the accommodating space, and a coil assembly for driving the magnet assembly. The magnet assembly includes a first magnet module and a second magnet opposite to each other, the coil assembly includes a coil and a coil support for supporting the coil. The coil support includes a support body and a plurality of supporting legs. The supporting legs extend from the support body and are fixed to the housing. The coil is supported by the support body between the first magnet module and the second magnet module.

Abstract: A vibration motor is provided in the present disclosure. The vibration motor includes a stationary part, a vibration part and an elastic connector. The stationary part includes a housing providing an accommodating space. The vibration part is suspended within the accommodating space by the elastic connector. The stationary part comprises a coil, and the vibration part comprises a first magnet set and a second magnet set; the first magnet set and the second magnet set are respectively disposed at two opposite sides of the coil to generate a closed magnetic loop. The first magnet set includes a first left magnet, a first middle magnet and a first right magnet, the second magnet set includes a second left magnet, a second middle magnet and a second right magnet which are opposite to the first left magnet, the first middle magnet and the first right magnet respectively.

Abstract: A vibrating motor is provided in the present disclosure. The vibrating motor includes a housing providing a receiving cavity, a PCB fixed on the housing, a coil received in the receiving cavity and a magnetic assembly opposite to and keeping a distance from the coil. The coil includes a lead wire; the housing includes a base with a plurality of sidewalls. One of the sidewalls adjacent to the coil provides a supporting platform protruding from the receiving cavity. The PCB is positioned on the supporting platform. The lead wire extends to the supporting platform, and electrically connected to the PCB.

Abstract: A vibration motor is provided in the present disclosure. The vibration motor includes a housing providing an accommodating space, and a first vibration system and a second vibration system elastically suspended within the accommodating space. The first vibration system includes at least one permanent magnet, and the second vibration system includes at least one magnetic force generation part opposite to the permanent magnet. A magnetic field generated by the magnetic force generation part interacts with the permanent magnet to drive the first vibration system and the second vibration system to vibrate in the housing.

Abstract: A vibrating motor is provided in the present disclosure. The vibrating motor includes a shell, a vibrating module, a magnet module, a coil module and an elastic assembly. The shell provides a receiving cavity for receiving the vibrating module. The vibrating module includes a first vibrating member and a second vibrating member, and the magnet module receives in the vibrating module. The coil module is disposed under the magnet module; the elastic assembly includes a pair of a first elastic parts and a second elastic part. The first elastic parts suspend the vibrating module in the shell; and the second elastic part connects the first vibrating member with the second vibrating member. The magnet module is received in at least one of the first vibrating member and the second vibrating member.

Abstract: Disclosed herein are apparatus and methods for linear actuators that can deliver strokes and forces at different values. The linear actuators include both multi-coil and single-coil actuator designs. The linear actuators include a controller that is removably or permanently coupled to a piston assembly having any number of coils. An encoder may also be removably or permanently coupled to the piston assembly. The piston assembly, controller and encoder move as one unit during actuation of the linear actuator.

Abstract: An apparatus comprises multiple electrically conductive loops, an elongated tubular ferromagnetic shield, and an elongated tubular superconductive inner shield. The superconductive inner shield is positioned within the ferromagnetic shield. Each conductive loop includes (i) a thrust segment extending from a first end of the superconductive inner shield outside the ferromagnetic shield to a second end of the superconductive inner shield and (ii) a return segment passing through an interior passage of the superconductive inner shield from the second end of the superconductive inner shield to the first end of the superconductive inner shield. The conductive loops can be spatially arranged relative to a uniform external magnetic field so that interaction between the external magnetic field and electrical current flowing in the conductive loops results in asymmetric magnetic flux density around, and non-zero net force exerted on, the conductive loops.

Abstract: A power conversion device in which a plurality of converter cells are connected in series with one another. The converter cells each include two or more semiconductor devices, an energy storage element and a bypass element including a constituent element for setting the bypass element to be close-circuited by detecting abnormality of a converter cell, and including a constituent element for controlling, among the semiconductor devices, a semiconductor device connected in parallel with the bypass element to set in a turn-on state, at the same time when the bypass element is set close-circuited or in advance of its close circuit.

Abstract: The proposed Power Management Integrated Circuit(PMIC) features the option to synchronize the charge-pump of a PMIC with the system clock, and then to swap and self-oscillate and skip pulses, when the digital controls of the PMIC send a first order to the charge-pump. The clock control circuitry of the PMIC also features the option for the charge-pump to then swap and use the system clock again, when the digital controls of the PMIC send a second order to the charge-pump. The designed transition of the clock from clock sync-mode to self-oscillate, and from self-oscillate back to clock sync-mode, does not present any phase discontinuity.

Abstract: Certain embodiments of the present invention include an apparatus comprising a charge pump, configured to provide an output voltage at an output node of the charge pump, and a charge pump regulator circuit coupled to the charge pump. One such charge pump regulator circuit is configured to control the charge pump to increase the output voltage during a first period of time. Such a charge pump regulator circuit can also cause a node of a circuit coupled to the output node of the charge pump to reach a target voltage level during a second time period.

Abstract: A switching mode DC/DC power converter for delivering a direct current to a pulse radar unit. A first switching element connects and disconnects the power converter from a power source in each cycle of the power converter. An inductor charges and discharges in each cycle. A capacitor maintains a DC output voltage as the inductor charges and discharges in each cycle. A second switching element transfers energy from the inductor to the capacitor when the first switch disconnects the switching mode power converter from the power source. A control loop regulates the voltage with a time constant, to a predetermined value by controlling the first switching element. An on time for the first switching element in each cycle is chosen to allow the current through the inductor to fall to zero in each cycle. The cycle is shorter than RF pulse duration and time constant of the control loop is longer than the RF pulses.

Abstract: Disclosed is a voltage regulator circuit configured to selectively operate the voltage regulator circuit in a first mode of operation and a second mode of operation. The voltage regulator can change operation of the voltage regulator circuit between the first mode of operation to the second mode of operation in response to a change in a sensed load condition of the voltage regulator circuit. The voltage regulator can change operation from the second mode of operation to the first mode of operation in response to the sensed load condition changing from the second load condition to the first load condition, but only when the sensed load condition has not changed in a given direction between the first load condition and the second load condition for at least a predetermined period of time T.

Abstract: A boost regulator that selectively operates in an asynchronous mode, a synchronous mode, or an adaptive mode. In the adaptive mode, the boost mode regulator controls a high side switch according to an adaptive dead time. Adaptive mode allows the boost regulator to operate more efficiently than in asynchronous mode.

Abstract: A circuit and method for providing an improved current monitoring circuit for a switching regulator. A circuit providing switching regulation with an improved current monitor, comprising a pulse width modulation (PWM) controller configured to provide P- and N-drive signals, an output stage connected to said PWM controller and configured to provide switching, comprising a high-side and low-side transistor, driven by said P- and N-drive signals, respectively, a sense circuit configured to provide output current sensing from the output stage during a sampling period when the N-drive signal is active, and a sampling timing generator configured to provide a an n-sampling signal, nsample, to the sense circuit, wherein a start of the n-sampling signal is delayed by a first delay after the sampling period and the n-sampling signal is ended prior to an end of the sampling period by a second delay.

Abstract: Embodiments described herein relate to a circuit including a DC-to-DC converter and a switching device to selectively isolate an input voltage from an input node of the DC-to-DC converter. The circuit also includes a controller coupled to the input node and to the switching device. The controller is configured to apply a test voltage to the input node, to enable the switching device to be switched from a non-conductive state to a conductive state if a voltage on the input node is above a threshold while the test current is applied to the input node, and to restrict the switching device from being switched from the non-conductive state to the conductive state if the voltage on the input node is below the threshold while the test current is applied to the input node.

Abstract: According to one embodiment, a power supply circuit is adapted to turn on a switching transistor connected between an input terminal and an output node and supply current via an inductor to a capacitor connected to the output node, so as to obtain an output voltage from an output terminal connected to the capacitor. A detection signal according to current flowing in the inductor or a detection signal according to a comparison result between the output voltage and a reference voltage are detected at a predetermined time, and an ON-time of the transistor is controlled in accordance with the detection signal.

Abstract: A power supply device, including: a switching structure for controlling a continuous current in an inductive load on the basis of at least one control signal of a power switch; and anomaly detection elements, generating at least one item of information about the detection of an anomaly of the open circuit type in the wiring from the load to the switching structure. The anomaly detection elements include: elements for measuring the current flowing in the inductive load; elements for comparing the measured current continuously with a threshold value; and elements for counting a time interval during which the measured current remains continuously below the threshold value, delivering the anomaly detection information if the counted time interval>a reference time interval, which is k times greater than a period of the control signal, where k>1, and if the duty cycle of the control signal>a threshold value.

Abstract: The low input voltage boost converter with peak inductor current control and offset compensated zero detection provide a boost converter scheme to harvest energy from sources with small output voltages. Some embodiments described herein includes a thermoelectric boost converter that combines an IPEAK control scheme with offset compensation and duty cycled comparators to enable energy harvesting from TEG inputs as low as 5 mV to 10 mV, and the peak inductor current is independent to first order of the input voltage and output voltage. A control circuit can be configured to sample the input voltage (VIN) and then generate a pulse with a duration inversely proportional to VIN so as to control the boost converter switches such that a substantially constant peak inductor current is generated.

Abstract: A DC-DC converter includes n number of first series circuits each including an inductor and a switching element and a second series circuit in which n number of rectifier elements are connected in series with a same rectification direction. When n=2, one end of the second series circuit is connected to a node between an inductor and a switching element in the first series circuit and the other end of the second series circuit is connected to one end of a smoothing capacitor and one end of a load. A node between an inductor and a switching element is connected to a node between the rectifier elements via a capacitor. The odd-numbered switching element and the even-numbered switching element in the order of connection to the second series circuit are complementarily driven.

Abstract: In one implementation, a voltage converter includes a driver providing a gate drive for a power switch and a sense circuit coupled across the power switch. The gate drive provides power to the sense circuit, and the sense circuit provides a sense output to the driver corresponding to a current through the power switch. In one implementation, the sense circuit includes a high voltage (HV) sense transistor coupled between a first sense input and a sense output, a delay circuit configured to be coupled to the gate drive to provide power to the HV sense transistor when the gate drive is high, and a pull-down transistor configured to couple the sense output to a second sense input when the gate drive is low.

Abstract: A buck-boost power amplifier receiving a supply voltage and providing an output having a voltage swing higher than the supply voltage is provided. The buck-boost power amplifier comprises a buck power stage, a boost power stage, an inductor, and a non-linear pulse width modulator. The buck power stage and the boost power stage are independently controlled by the non-linear pulse width modulator. The non-linear pulse width modulator switches the buck-boost power amplifier between a buck mode wherein the output provides a voltage lower than the supply voltage and a boost mode wherein the output provides a voltage higher than the supply voltage.

Abstract: Resonant power converters that replace the conventional impedance matching stage with series or parallel connections between resonant inverters and resonant rectifiers are provided. Two or more resonant rectifiers can be connected in series or in parallel to the resonant inverter to provide impedance matching. Similarly, two or more resonant inverters can be connected in series or in parallel to the resonant rectifier to provide impedance matching. Electrical isolation of DC voltage between input and output is provided using only capacitors.

Abstract: A flyback controller featuring bidirectional power control and parallelly-connected power modules is based on flyback DC-DC converters for allowing bidirectional energy flow and transformation. The flyback controller includes two bidirectional DC-DC converters that are connected in parallel. The bidirectional DC-DC converters are electrically connected with a digital-signal processor. The digital-signal processor controls the bidirectional DC-DC converters and current thereof, so that the current flows evenly across the bidirectional DC-DC converters. Thereby, the flyback controller has advantages about simplified components and increased power output, and is suitable for testing secondary batteries.

Abstract: An example relates to a method for operating a converter comprising a primary side of a transformer and a secondary side of the transformer, wherein a switching element is used for conveying energy from the primary side to the secondary side, the method comprising (i) determining a voltage drop across the primary side of the transformer; (ii) determining at least one additional voltage drop across at least one component of the converter's primary side; and (iii) determining an input voltage at the converter via the voltage drops.

Abstract: An example relates to a method for operating a converter comprising (i) determining whether a valley for switching the converter in a quasi-resonant mode is available within a predetermined time range; (ii) selecting the valley if it is available within the predetermined time range; and (iii) changing the mode for operating the converter if the valley is not available within the predetermined time range.

Abstract: A power conversion apparatus including a flyback power conversion circuit, a control chip and a detection auxiliary circuit is provided. The flyback power conversion circuit converts an input voltage into a direct current (DC) output voltage. The control chip generates a pulse width modulation (PWM) signal for controlling operations of the flyback power conversion circuit. The detection auxiliary circuit assists the control chip in obtaining a first detection voltage via a multi-function detection pin of the control chip within an enabling period of the PWM signal, so as to execute an over current detection according to the first detection voltage. Besides, the detection auxiliary circuit assists the control chip in obtaining a second detection voltage via the multi-function detection pin within a disabling period of the PWM signal, so as to execute a valley voltage detection according to the second detection voltage.

Abstract: A power supply apparatus includes: converters configured to switch an input power to convert the input power into a total direct current (DC) power; and a controller configured to control DC power-to-total DC power ratios of the converters based on at least one of whether or not the converters are operated or operation temperatures of the converters.

Abstract: A switching power converter is provided that switches between low-bandwidth PI control and a high-speed control of an output voltage responsive to comparing the output voltage to an upper output voltage limit and to a lower output voltage limit. The switching power converter adapts the upper and lower voltage limits responsive to a load demand.

Abstract: A switching power supply includes a main switching element that is connected to a primary coil of a transformer and switches a main current ON/OFF, and a secondary switching element connected in parallel to the main switching element and that has a lower power capacity than the main switching element. The switching power supply also includes a control circuit that controls these switching elements. The control circuit includes: a main driver circuit that generates, in accordance with a control signal generated according to an output voltage from a secondary coil of the transformer, a main drive signal for switching the main switching element ON/OFF; a secondary driver circuit that generates a secondary drive signal for switching the secondary switching element ON/OFF according to the control signal; and an enable control circuit that deactivates the main driver circuit when a power consumption of a load is less than a threshold value.

Abstract: An integrated circuit (IC) for controlling the discharge of a capacitor coupled across first and second input terminals of a power converter circuit, wherein the first and second terminals for receiving an ac line voltage. The IC includes a switching element coupled across the first and second input terminals and a detector circuit. The detector circuit including first and second comparators that produce first and second output signals responsive to a zero-crossing event of the ac line voltage. The first and second output signals being used to generate a reset signal coupled to a timer circuit responsive to the zero-crossing event. When the reset signal is not received within a delay time period, the timer circuit outputs a discharge signal that turns the switching element on, thereby discharging the capacitor.

Abstract: In accordance with an embodiment, a converter includes a power factor controller that varies the switching frequency of a switching transistor in accordance with a signal representative of power at the input of the converter.

Abstract: The present disclosure provides A DC/DC power supply system that includes a primary side and a secondary side to generate an output DC voltage from an input DC voltage. The power supply also includes adaptive clamping circuitry configured to generate an adjustable clamping voltage and/or current to limit a Vds breakdown voltage for a plurality of switches of the secondary side.

Abstract: A DC-DC converter includes a transformer, a switching circuit provided on the primary side of the transformer, and a rectifier circuit provided on the secondary side of the transformer. The rectifier circuit includes a first rectifier part that is serially connected body of a first transistor and a second transistor having a first electrode connected to a second electrode of the first transistor. The first and second transistors each include a parasitic diode connected forward between the second and first electrode, and the withstanding voltage between the first and second electrodes of the first transistor is higher than the withstanding voltage between the first and second electrodes of the second transistor.

Abstract: A method is shown to create soft transition in selected topologies by preserving the leakage inductance energy during the dead time and using several techniques to supplement the energy require to discharge the parasitic capacitance of the primary switchers and obtain zero voltage switching. One technique consists in a current pulse injection across the synchronous rectifiers during the dead time and prior the turn off of the synchronous rectifiers. A second technique consist in tailoring the magnetizing current through frequency modulation to increase the energy in the leakage inductance and use that energy to discharge the parasitic capacitance of the primary switchers and at lighter load to have a magnetizing current which exceeds the current through the output inductor at the end of the dead time. The third technique is interleaving two converters and sharing a couple inductance in a way to lower the current through each output inductor under the level of the magnetizing current at its lowest amplitude.

Abstract: In a switching power supply circuit (1A) of the invention, a low-voltage node capacitor (5) is connected between a primary-side low-voltage stable potential node (LN1) and a secondary-side low-voltage stable potential node (LN2), and a high-voltage node capacitor (4) is connected between a primary-side high-voltage stable potential node (HN1) and an anode of a rectifier element (31). Thereby, it is possible to provide the switching power supply circuit which achieves, with a simple configuration, both of noise reduction and potential stabilization of stable potential nodes.

Abstract: An uninterruptible power supply system includes a plurality of uninterruptible power supply devices, and each uninterruptible power supply device includes a conversion circuit, an inversion circuit, a DC positive bus, a DC negative bus, and a capacitor. The uninterruptible power supply system includes a first fuse connected between DC positive buses of two uninterruptible power supply devices, and a second fuse connected between DC negative buses of the two uninterruptible power supply devices. DC voltages between the plurality of DC positive buses and between the plurality of DC negative buses can be made uniform and a cross current can be suppressed. Even when one uninterruptible power supply device fails and an overcurrent flows between the two DC positive buses and between the two DC negative buses, the failure range can be narrowly limited by the first and second fuses.

Abstract: An uninterruptible power supply system includes a plurality of uninterruptible power supply devices, and each uninterruptible power supply device includes a conversion circuit, an inversion circuit, a DC positive bus, a DC negative bus, and a capacitor. The uninterruptible power supply system includes a first wiring connected between DC positive buses of two uninterruptible power supply devices, and a second wiring connected between DC negative buses of the two uninterruptible power supply devices. The operation of all uninterruptible power supply devices is stopped in response to an absolute value of a current flowing through a bundle of the first and second wirings exceeding an upper limit value.

Abstract: To reduce the number of mounted components in the power conversion device and drive device. Each high-side transistor and low-side transistor has an EGE-type structure of (emitter-gate-emitter type). A high-side driver includes a first pull-up transistor configured to apply a first positive voltage to a gate based on an emitter of the high-side transistor, and a first pull-down transistor configured to couple the gate to the emitter. A low-side driver includes a second pull-up transistor configured to apply a second positive voltage to the gate based on an emitter of the low-side transistor, and a second pull-down transistor configured to couple the gate to the emitter.

Abstract: A five-level converting device includes a first switch module, a second switch module and a third switch modules each connects to a neutral point, a positive terminal and a negative terminal of a bus capacitor module. A first switch module includes a plurality of bidirectional switching circuits cascaded to each other, and each bidirectional switching circuit includes two first switching units reversely connected in series. Second switch module includes a plurality of second switching units connected in series. Third switch module includes a plurality of third switching units connected in series. A first flying capacitor unit is connected across the first switching module and a second switch module, and a second flying capacitor unit is connected across the first switching module and a third switching module. The first flying capacitor unit and the second flying capacitor unit are connected to different connection points between the first switch units respectively.

Abstract: A power rectifier rectifies alternating electric current by using a controller in the power rectifier to control a first delay corresponding to a first delay circuit in the power rectifier to turn on a high side switch in the power rectifier, wherein the high side switch provides a path for power from an input voltage line of the power rectifier to an output voltage line of the power rectifier. The controller controls a second delay corresponding to a second delay circuit in the power rectifier to maintain the high side switch in an on state so as to change a switching state of the high side switch based on detection, by a current inversion detector, of a current inversion associated with the input and output voltage lines of the power rectifier.

Abstract: A five-level converting device includes an AC terminal, a bus capacitor module having a positive terminal, a negative terminal and a neutral terminal, a first switch module and a second switch module. The first switch module includes a bidirectional switching circuit, and the bidirectional switching circuit includes two first switching units reversely connected in series. The second switch module includes two second switching units, two third switching units, two fourth switching units, and two fifth switching units. The two second switching units are cascaded and connected to the two fourth switching units in parallel. The third, the fourth and the fifth switching units are cascaded and are connected to the bus capacitor module in parallel. Two different connection points of the first switch module are connected to the third switching units and fifth switching units through two flying capacitor modules respectively.

Abstract: An electric power conversion device includes: a switching element; a collector side wiring connected to a collector side of the switching element; an emitter side wiring connected to an emitter side of the switching element; a detection circuitry configured to detect an induction voltage generated in the collector side wiring or the emitter side wiring when a current flows through the collector side wiring or the emitter side wiring; and a comparison circuitry configured to compare the induction voltage detected by the detection circuitry and a predetermined threshold voltage determined in advance to each other.

Abstract: A direct current (DC)-alternating current (AC) power convertor is disclosed. The DC-AC power converting circuit may include an inverter configured to convert the DC power into first output power, a piezoelectric transforming unit including piezoelectric transformers connected in parallel to an output terminal of the inverter, and each piezoelectric transformer of the piezoelectric transformers configured to transform the first output power to second output power, and an output configured to add the second output power output from the each of the piezoelectric transformer and to output AC power, wherein each piezoelectric transformer has a resonance frequency.

Abstract: We describe a nanopositioning device comprising: a mount and a moving stage held within said mount, preferably by sets of flexures on opposite sides of the stage such that the stage is displaceable in a longitudinal direction within said mount. A piezoelectric actuator is mechanically coupled to said stage to controllably displace the stage in a longitudinal direction. In embodiments the flexures comprise metal leaves having a plane extending between the stage and the mount perpendicular to said longitudinal direction. The device includes various additional features to improve resolution, frequency response and the like.

Abstract: A drum-type wide-frequency piezoelectric power generation apparatus may include a protective layer pasted on piezoelectric layer through epoxy resin glue or other conductive adhesives. The piezoelectric layer is pasted on the base layer through epoxy resin or other conductive adhesives. One side of piezoelectric vibrators are fixed on the end cap “a” through the clamp and are away from a first permanent magnet. The end cap “a” provided an octagonal boss “a”. There are bosses “b”, “c”, “d” on the surface of boss “a”. The four piezoelectric vibrators are fixed on four symmetry planes of bosses “a”, “b”, “c”, “d”. The four planes of end cap “a” are fixed on piezoelectric vibrator corresponding to four straight slots respectively, which are used to fix the clamp. The auxiliary magnet is closer to the center of end cap “b” than second permanent magnet. Each of second permanent magnets has a corresponding auxiliary magnet. The first second permanent magnets are mutually exclusive.