1241results about How to "Small ripple" patented technology

The invention discloses a two-bed duplex tube medical diagnosis X-ray high frequency high voltage generator, which comprises a power supply and a central control unit, and also comprises a high frequency inverter circuit, a pulse-width modulation drive circuit and a high voltage commutation circuit. The generator converts the industrial power supply into two way high frequency high voltage, and then obtains positive end DC high voltage and negative end DC high voltage after the rectification and the filter to supply an X-ray pipet for working. Because the frequency is high and the high voltage ripple after the rectification and the filter is minimum, causing the X-ray pipet of a radiographic table and the X-ray pipet of an electric perspective table to work in turn under the condition of arranging only one set of high voltage supply. The equipment investment is saved, and the work of using the X-ray diagnosis for the medical staff is convenient. Being served as the high voltage supply, the invention is also suitable for the safety detection fields such as the industrial fault detection, the civil aviation, the station, the custom, etc., and supplies the stable high quality high voltage for the equipment.

The invention discloses a grid-connected photovoltaic inverter and relates to equipment which employs irreversible DC power input conversion as AC power output for a semiconductor device with a control electrode and is used for being used together with a power supply system of a power supply. The equipment consists of a photovoltaic array module, four identical switching tubes, two identical diodes, four identical capacitors, an inductor and a power grid; and the topology ensures not to generate DC component or common mode current for the power grid. Meanwhile, the inverter has low output current ripple and higher efficiency, and overcomes the defects that the conventional full-bridge inverters and other types of transformerless photovoltaic inverters generate DC component in the power grid and generate common mode current or / and higher current ripple. Compared with a half-bridge inverter, the grid-connected photovoltaic inverter reduces the differential mode voltage and current ripple by half.

The invention relates to a high power factor DCM Boost PFC converter comprising a main power circuit and a control circuit. The main power circuit comprises an input voltage source vin, an EMI filter, a diode rectification circuit RB, a Boost inductor Lb, a switch tube Qb, a diode Db, an output capacitor Co and a load RLd. The high power factor DCM Boost PFC converter is characterized in that the control circuit adopts an output signal which adopts duty ratio as changing rule to drive the switch tube Qb. Adopting the varying duty ratio control, the high power factor DCM Boost PFC converter can improve the PF value to about 1 in the AC input voltage range of 90-265 V, increase the inductance capacity, obviously decrease the inductive current ripple, obviously reduce the effective value of the inductive current and correspondingly reduce the effective value of the current of the switch tube, has high input power factor and small output voltage ripple and contains less input current harmonic waves. The conduction loss of the high power factor DCM Boost PFC converter is reduced, and the efficiency is improved.

The invention discloses a multi-port isolating bidirectional DC-DC (direct current to direct current) converter which is used for a mixed energy storing system. The converter comprises a phase-shifting transformer and a primary side circuit and a secondary side circuit which are respectively connected with a primary side and a secondary side of the phase-shifting transformer; the secondary side circuit comprises a two-path Buck / Boost converting circuit, wherein the two-path Buck / Boost converting circuit comprises two input / output ends and two bridge arm midpoints and the two bridge arm midpoints are respectively connected with two ends of the secondary side of the phase-shifting transformer; and the primary side circuit comprises at least one two-path Buck / Boost converting circuit, wherein the two-path Buck / Boost converting circuit comprises two input / output ends and two bridge arm midpoints and the two bridge arm midpoints are respectively connected with two ends of the primary side of the phase-shifting transformer. The invention further discloses a voltage matching and controlling method of the multi-port isolating bidirectional DC-DC converter and the mixed energy storing system comprising the converter. Compared with the prior art, the multi-port isolating both-way DC-DC converter can realize complete matching of voltage at two ends of a transformer and can prolong the service lives of a storage battery and a super capacitor.

The invention relates to a constant time control method, a control circuit and a switching regulator using the same. The constant time control method includes: detecting output voltage of the switching regulator to obtain voltage feedback signals for representing the output voltage; detecting flow inductance current to obtain triangular wave signals for representing the inductance current; overlaying the triangular wave signals and the voltage feedback signals to generate a first control signal; calculating errors between the voltage feedback signals and first standard voltage, and compensating the errors to obtain a compensating signal; enabling the compensating signal to keep roughly constant; comparing the first control signal with the compensating signal to generate a second control signal; and controlling opening and closing of a power switching element in the switching regulator according to the second control signal and a constant time control signal so as to keep roughly constant of electric signals output by the switching regulator.

The invention discloses a high voltage gain bidirectional DC-DC (direct current-direct current) converter based on switching capacitors and coupling inductors. The high voltage gain bidirectional DC-DC converter based on the switching capacitors and the coupling inductors is formed by combining Boost convertors, the coupling inductors and the switching capacitors in interleaved mode. An electric circuit of the high voltage gain bidirectional DC-DC converter based on the switching capacitors and the coupling inductors comprises n / 2 coupling inductors T1[L1, L2], T2[L3, L4]... T(n / 2)[L(n-1), Ln], 2n high frequency power switches S1, S2... Sn and Q1, Q2... Qn, N-1 high frequency switching capacitors C1, C2... C(n-1) and two input and output filter capacitors CL and CH. The high voltage gain bidirectional DC-DC converter based on the switching capacitors and the coupling inductors can effectively reduce current stress of a low voltage side power device and voltage stress of a high voltage side power device, further reduces the ripple of an input current and decrease the inductor size by using the coupling inductors, improves efficiency of an exchanger, and achieves bidirectional DC-DC conversion high in efficiency and high in voltage gain. According to high voltage gain bidirectional DC-DC converter based on the switching capacitors and the coupling inductors, an interleaved technology, a magnetic integration technology and a switching capacitor technology are combined, and therefore novel topology of the high voltage gain bidirectional DC-DC converter based on the switching capacitors and the coupling inductors not only has characteristics of being low in ripple of the input current and easy to design in EMT mode of an interleaved converter, but also achieves the purposes that a transformation ratio of input voltage and output voltage is large and switch voltage stress is low.

A single-inductance double-output switch power supply based on ripple control comprises a power level module, a filter and voltage sampling module, a secondary voltage sampling module, a secondary ripple control module, a primary voltage sampling module, a primary control module and a driving module, wherein the output of the power level module is connected with the filter and voltage sampling module, the output of the filter and voltage sampling module is connected with each of the secondary voltage sampling module and the primary voltage sampling module, the output of the secondary voltage sampling module is connected with the secondary ripple control module, the output of the primary voltage sampling module is connected with the primary control module, the outputs of the secondary ripple control module and the primary control module are connected with the driving module, and the output of the driving module is connected with the power level module and the secondary ripple control module and also outputs a slope compensation power source Islope signal to the secondary voltage sampling module.

The invention discloses an input parallel and output parallel combination converter under the control of a common phase-shifting angle. A main circuit comprises more than two phase-shifting circuits under the control of the common phase-shifting angle; each phase-shifting circuit consists of a transformer with leakage inductance and two bridge circuits which are connected through the transformer;and the input ends of all the phase-shifting circuits are connected in parallel and the output ends of all the phase-shifting circuits are connected in parallel. Under the control of the common phase-shifting angle, input current of all the phase-shifting circuits is equal and output current of all the phase-shifting circuits is equal, natural current sharing is realized, current sharing control loops are not needed to be added, each phase-shifting circuit unit is not needed to be subjected to current sampling, control is greatly simplified, power density and stability of the combination converter are improved, and cost is reduced.

The invention relates to a closed-loop control charge pump circuit, which comprises a basic charge pump circuit and a control loop. The control loop comprises the following circuits which are connected in turn: a sampling circuit, a comparer, an oscillation control circuit, and an oscillator, wherein the sampling circuit is connected with a voltage output end (Vout) of a basic charge pump, and isused for sampling the voltage value of the Vout and generating a sampling voltage value V1 corresponding to the voltage value of the Vout according to a predefined function mapping relation f; the comparer is used for comparing the voltage value V1 with a preset reference voltage Vref and outputting the comparison result V2; the oscillation control circuit receives the comparison result V2 and generates a control signal Ctr1 according to the V2 value; and the oscillation frequency of the oscillator is controlled by the control signal Ctr1 to change continuously, and the oscillator outputs theoscillation frequency as the working frequency of the basic charge pump. Thus, the frequency of the oscillator of the charge pump circuit can be adjusted continuously and dynamically, and the whole charge pump circuit has good power following characteristics and reduces the energy consumption.

The invention provides a clock adjustment circuit and an adjustment method for a clock circuit. The clock adjustment circuit comprises a clock buffer amplifier, a phase discriminator and a duty cycle adjustment circuit, wherein the clock buffer amplifier is used for receiving an external differential clock signal, shaping the differential clock signal into a single-end square wave clock signal and outputting the single-end square wave clock signal; the phase discriminator is used for receiving the single-end square wave clock signal from the clock buffer amplifier and a feedback signal from the duty cycle adjustment circuit, comparing the phase of the single-end square wave clock signal with the phase of the feedback signal to acquire a phase difference, and outputting the phase difference; and the duty cycle adjustment circuit is used for adjusting the duty cycle of the feedback signal by using the phase difference to acquire an adjusted feedback signal. The differential signal is shaped into the single-end square wave clock signal, the single-end square wave clock signal is compared with the feedback signal to acquire the phase difference, and the duty cycle is adjusted according to the phase difference, so that the complexity of duty cycle adjustment and hardware implementation can be effectively reduced, phase errors and the ripple waves of control voltage can be reduced, and adjustment accuracy is improved.

A control circuit and method for a ripple regulator system generate a ripple signal in-phase and synchronous with an inductor current of the ripple regulator system, and extract a ripple information proportional to the amplitude of the ripple signal. The ripple signal is used for triggering control in PWM signal generation to make the ripple regulator system have small ripples and better loop stability simultaneously. The ripple information is used to improve the output offset of the ripple regulator system that is caused by the ripple signal.

A charge pump circuit with bipolar output comprises a first switch capable of selectively connecting a first input terminal of a transfer capacitor to a voltage source, a second switch capable of selectively connecting a first input terminal of a first storage capacitor to said first input terminal of said transfer capacitor; a third switch capable of selectively connecting a second input terminal of said transfer capacitor to said voltage source; a fourth switch selectively connecting said second input terminal of said transfer capacitor to a ground terminal; and a fifth switch selectively connecting said second input terminal of said transfer capacitor to a second input terminal of a second storage capacitor. The charge pump circuit is collocated with clock signals to be selectively driven by a four-phase signal so as to produce bipolar voltages with magnitudes higher than the input voltage with minimum number of switches and capacitors and also accomplish the highest efficiency.

The invention provides a PFC (power factor correction) control method with high input power factor and a control circuit thereof. The method comprises the steps of controlling a switching tube to be switched on and switched off according to the principle of leading impulse area to be equivalent, and leading input inductive current and sinusoidal half-wave current to have the equivalent impulse area in each switching period, thereby realizing the high power factor (PF); furthermore, the higher the switching frequency, the closer to 1 the PF value is. In the control circuit, a circuit topological structure of a Boost converter and a control circuit for realizing a variable duty ratio sequence jointly constitute a PFC stage of a commonly used LED (light-emitting diode) driving power supply, the front stage of the PFC stage is connected with the output end of a non-controllable rectifier bridge of a single-phase diode via an input filter capacitor, the back stage of the PFC stage is connected with a DC / DC (direct current / direct current) stage of the commonly used LED driving power supply via an output filter inductor and an output filter capacitor. By adopting the PFC control method, not only the very high input power factor can be realized, but also output voltage ripple can be reduced; furthermore, the control circuit is simple and easy to realize an analog circuit, thereby being conductive to large-scale integration.

Provided is a power supply device, which is capable of coping with semiconductor light source loads to be set in various ways, and has high efficiency, in which a current to be supplied to each of the loads has a small ripple. The power supply device supplies power to a semiconductor light source load and lights the semiconductor light source load, and includes: a DC-DC converter; and a controller. The DC-DC converter includes an inductance element and a switching element, and performs voltage conversion by storing energy in the inductance element from an input power source when the switching element is on, and discharging the energy, the energy being stored in the inductance element, to a load side when the switching element is off. The controller controls ON / OFF operations of the switching element so that an output current of the DC-DC converter can be the same as a target value. In the power supply device, means for regulating timing of turning on the switching element so that a current flowing through the inductance element can flow in a continuous mode operation is provided at least in the controller.

A cascaded H bridge multilevel converter and a control method thereof are provided. The converter includes two passive DC buses and a conversion circuit of which the three phases are of the same structure. The conversion circuit includes n cascaded inverter modules of the same structure. Each inverter module includes a photovoltaic sub module and an H bridge unit. Each photovoltaic sub module is a three-port interleaved parallel Boost LLC DC converter. Of the two input ports on the primary side of each photovoltaic sub module, one input port is connected with the output end of a solar photovoltaic power generation module, and the other input port is connected across the two DC buses. The output port of each photovoltaic sub module is connected with the input port of the corresponding H bridge unit. In each phase of conversion circuit, the output ports of the n H bridge units are cascaded to form an output port of the phase of conversion circuit. Photovoltaic module maximum power point tracking and LLC DC converter output voltage control are realized by controlling the duty ratio and switching frequency of a switching tube. Therefore, the problem that the intra-phase and inter-phase output power of the cascaded H bridge converters in a large-scale photovoltaic grid-connected power generation system is imbalanced is solved.

The invention discloses a boost type converter for realizing high-gain voltage multiplication by coupling inductors, comprising two switching tubes, two clamping diodes, a freewheel diode, an output diode, a clamping capacitor, a voltage-multiplying capacitor, an output capacitor and two coupling inductors respectively provided with two windings. The two coupling inductors are utilized to improve the gain of the converter and reduce the voltage stress of the switching tubes and the diodes in the converter, and the leakage inductance of the coupling inductors is utilized to realize the zero current turn-on of the switching tubes and the soft turn-off of the diodes. A clamping circuit consisting of the clamping diodes and the clamping capacitor absorbs a switching tube turn-off voltage spike caused by the leakage inductance and realizes the lossless transfer of energy. A voltage-multiplying circuit is utilized to further improve the gain of the converter and reduce the voltage stress of the switching tubes and the output diode, and staggered parallel connection is utilized to control and reduce ripple waves of input current.

The invention discloses a direct current switch power supply controlling circuit, which comprises a pulse-width modulating comparator, a controlling unit and a logic driving unit which are connected in turn, wherein output square-wave signals of the pulse-width modulating comparator are input in a first input end of the controlling unit, maximum duty cycle square-wave signal is input in a second input end, the output end is connected with the input end of the logic driving unit, when the duty cycle of output square-wave of the pulse-width modulating comparator which is input is lager than the maximum duty cycle, the controlling outputs the square-wave with 100% duty cycle. The direct current switch power supply controlling circuit realizes smooth conversion from the maximum duty cycle to 100% duty cycle through improving the controlling unit circuit of a power supply controlling circuit, which increases respond speed of the circuit, reduces ripple of output voltage in the process of conversation of the circuit from the maximum duty cycle mode to 100% duty cycle mode, the design of the circuit is simple, and the cost of circuit reconstruction is saved.

It is an object to provide a surface-treated electro-deposited copper foil which has a low profile at a level equal to or excellent than that of low-profile surface-treated electro-deposited copper foils that have conventionally been supplied to the market and in which waviness affecting the straight line performance of wiring is small, and a method for manufacturing the same. In order to achieve this object, in the surface-treated electro-deposited copper foil, the maximum waviness height (Wmax) of the bonding surface to be bonded with an insulation layer-constituting material to be 0.05 μm to 0.7 μm, the maximum peak to valley height (PV) to be 0.05 to 1.5 μm, and the surface roughness (Rzjis) to be 0.1 μm to 1.0 μm. The electro-deposited copper foil used for the manufacturing of this surface-treated electro-deposited copper foil is manufactured by using a sulfuric acid base copper electrolytic solution obtained by adding 3-mercapto-1-propanesulfonic acid or bis(3-sulfopropyl)disulfide, a quaternary ammonium salt polymer having a cyclic structure, and chlorine, and using a cathode having small surface roughness, under electrolysis conditions of carrying out continuous first-step electrolysis to n-th-step electrolysis at two or more different levels of electric current density.

The invention provides a single-stage type isolated AC-DC converter based on an interleaved bridgeless PFC circuit and LLC resonance. The single-stage type isolated AC-DC converter comprises a front-stage interleaved bridgeless PFC circuit for converting an AC input voltage to a DC voltage, a primary side of a back-stage full-bridge LLC resonance circuit is of a full-bridge circuit structure, theoriginal side can realize switching tube zero-voltage soft turning-on, and a secondary side can realize diode zero current-current soft turning-off. The converter reduces the number of switching tubes, thereby improving the efficiency of the whole converter. The AC / DC part of the converter is an interleaved bridgeless PFC circuit, and two paths of input inductive currents are interleaved, so thatinput current ripples are greatly reduced; the converter can enable input current change to well follow input voltage to change, and realizes a power factor correction function; by controlling outputvoltage, the converter realizes stable DC voltage output; and at the same time, the converter has a high-frequency transformer, and can achieve electric isolation.

The invention discloses an isolated bidirectional DC-DC (direct current) converter realized by a coupling inductor, which comprises four power switch tubes with reverse parallel diodes and parallel capacitors, two auxiliary switch tubes with reverse parallel diodes, two clamping capacitors, a switch capacitor and two two-winding coupling inductors. The invention reduces the ripples of the low-voltage side current through the low-voltage side parallel structure, realizes the zero voltage shutoff of the power switch tubes through the parallel capacitors on the power switch tubes, realizes the zero voltage conduction of the power switch tubes through the leakage inductance of the coupling inductors, realizes lossless transfer of the leakage inductance energy through the auxiliary switch tubes and an active clamping circuit consisting of the reverse parallel diodes of the auxiliary switch tubes and the clamping capacitors, and increases / decreases the voltage of the converter through the serial structure of the high-voltage side windings of the two coupling inductors. The circuit has simple structure, all power switches work in a soft switch state, no energy consumption element is arranged in the circuit, and the converter efficiency is improved; and moreover, during the current conversion, the switch device does not experience voltage overshoot.

The invention provides a three-level half-bridge single-stage inverter and a control method thereof, belonging to the inverter field. One passage of voltage output circuit of the inverter consists of a power (V in ), two capacitors (C11 and C12), six power switch tubes (S1-S4, S9 and S10), two clamping diodes (D1 and D2), a transformer (T1), a filter inductor (L f1 ) and a filter capacitor (C f1 ), and another passage of voltage output circuit of the inverter consists of a power (V in ), two capacitors (C21 and C22), six power switch tubes (S5-S8, S11 and S12), two clamping diodes (D3 and D4), a transformer (T2), a filter inductor (L f2 ) and a filter capacitor (C f2 ). The inverter is formed by the differential combination of two three-level half-bridge DC converters with bidirectional power currents; the switch tube has low voltage stress and is suitable for high-voltage input sites; the load adaptability is strong and the dynamical performance is excellent. The three-level half-bridge single-stage inverter has two control methods as follows: a no-bias voltage semi-period working mode with two passages of inverters work in a half period respectively and a bias voltage full-period working mode with two passages of inverters work at the same time.

A power factor correction converter and a power factor correction conversion device, includes two groups of bidirectional switches, an autotransformer, a boost inductor, a bus filter capacitor, two front bridge arms; and a rear bridge arm; the front end of each group of bidirectional switches are connected to a coil of the autotransformer in one-to-one correspondence, and a rear end of each group of bidirectional switches is connected to one end of an AC input power grid; a central tap of the autotransformer is connected to an output end of the boost inductor, and an input end of the boost inductor is connected to the other end of the AC input power grid; a front end of each group of bidirectional switches is connected to a front bridge arm, and a rear end is connected to the rear bridge arm.

The invention discloses a CPT (contact-less power transfer) system based on a static capacitor array and a control method thereof, and belongs to the field of CPT system. In the CPT system, the static capacitor array is additionally arranged on a pick-up end circuit; a resonant inductor Ls on the pick-up end circuit is connected with the static capacitor array in parallel; two ends of load RL areconnected with an input terminal of an AD (analog-to-digital) sampling module through a voltage division circuit; an output terminal of the AD sampling module is connected with an input terminal of acontroller; and an output terminal of the controller is connected with the static capacitor array so as to control the static capacitor array to output different equivalent capacitance values. In thecontrol method of the CPT system, a segmented control method based on a soft-switching technology is provided for adjusting the equivalent capacitance values output by the static capacitor array in alogical operation manner, thereby realizing control of output voltage of the CPT system. The CPT system and the control method thereof have the advantages that the adjustment range of the output voltage of the CPT system is extended, the loss of a dynamic switch is reduced and the overall stability of the system is improved.

The invention discloses a staggered parallel flyback LED driving power supply and a PFM (pulse width modulation) control circuit thereof. A main circuit of the driving power supply is formed by staggering and parallel connection of two flyback converters, and comprises an alternating-current input end, an EMI (electromagnetic interference) filter, a bridge rectifier, the two parallel flyback converters, an output rectifier and an LED load. By the aid of the staggered parallel main circuit structure, current stress of switching tubes is reduced, input and output current ripple is reduced, the EMI filter design is simplified, power level of the driving power supply is increased, and the like. A PFM control method is adopted in the control circuit of the driving power supply; compared with a common PWM control method, the PFM control method has the advantages that by the aid of the PFM control circuit, the driving power supply can change in switching tube turning-on time and switching frequency simultaneously when the load changes, working loss during light load of the driving power supply is reduced, and power supply efficiency is improved. The driving power supply is suitable for applications of an LED driving power supply with an automatic dimming function.

The invention discloses a control method of a two-way direct current conversion device. The control method of the two-way direct current conversion device is suitable for high voltage and high power conversion sites, and can support frequent changing-over of power flow direction. Switching loss and circuit complexity can be balanced. At first an upper switch tube breakover time T 1 and a lower switch tube breakover time T 2 in a control cycle T s are calculated according to required pulse width modulation (PWM) control signal duty ratio D, and the ratio of T 1 to TS is D. In the process of practical control, one main circuit in the two-way direct current conversion device can be used as a reference subcircuit. The control on the reference subcircuit is that the upper switch tube and the lower switch tube in the reference subcircuit are controlled to be communicated in a complementary mode in each control circuit T s, and every time the upper switch tube and the lower switch tube are changed over, the dead time delta is added to carry out transition. Therefore the real breakover time of the upper switch tube is that T 1 subtracts the delta, and the real breakover time of the lower switch tube is that the T 2 subtracts the delta. The control on an un-referenced subcircuit is that control signals of all un-referenced subcircuits are the same, and differ by 180 degrees from the control signals of the reference circuit.

The invention relates to a standard Z source three-level T-shaped inverter and an SVPWM method thereof. A topology has boost features identical to boost features of a standard Z source network three-level NPC inverter, however, few switching elements are utilized, and efficiency is high. Compared with a three-level T-shaped inverter, functions of boost and voltage reduction of the topology can be achieved, direct connection of an upper bridge arm and a lower bridge arm is allowed, reliability is improved remarkably, dead time is eliminated, and waveform distortion is prevented. Compared with a Z source three-level diode clamped inverter, current at an input end is continuous, ripple waves are small, and the input end does not need to be connected with a large-capacitance array set in parallel. Compared with a standard Z source two-level inverter, output voltage has neutral point electric potentials, therefore, high frequency harmonic waves are small, a required filter is small, a switching frequency can be reduced, and switching loss is less. The SVPWM method is adopted to control the inverter, so that switching frequencies are decreased, switching loss is reduced, and harmonic contents of the output voltage are reduced.

The invention provides a boost charge pump circuit. The boost charge pump circuit omits a voltage regulator, utilizes feedback control to adjust an output voltage peak and guarantees that the output voltage is adaptable to step motor drivers of different applications; a boost charge pump continuously and repeatedly charge and discharge to maintain the stability of the output voltage, guarantees that the difference value of an output voltage value and a reference voltage are stable, enables output voltage ripples to be small and meets the requirements of the step motor drivers; a potential clamp module is utilized, the charging potential of a pump capacitor is limited, a circuit starting efficiency is improved, and accordingly power dissipation is reduced.

The invention relates to a direct current stabilized current power supply which realizes low ripple by IGBT series-parallel connection, and the invention belongs to the field of automatic control technology and power electronic technology and relates to a power change circuit based on a large capacity IGBT apparatus. The power change circuit comprises an incoming filter circuit, a phase shifting circuit, an input end rectification filter circuit, an energy storage circuit, a front reduction voltage chopper circuit, a front passive filter circuit, a back reduction voltage chopper circuit, a back passive filter circuit, an output end passive filter circuit, a voltage sensor circuit, a current sensor circuit and a control circuit used for controlling a whole circuit to work. Water cooling or forced air cooling can be applied to the direct current stabilized current power supply, and the direct current stabilized current power supply has the advantages that the power supply has high stability of current in a long term, low voltage (current) ripple, fast response, high regulation precision, small size, high efficiency and small noise of a device.