265results about How to "Improve power density" patented technology

A resonant converter equipped with a phase shifting output circuit includes a resonant circuit to receive input power and regulate to become at least one resonant power, a switch unit to switch an ON period for the input power to pass through the resonant circuit and a power transformation circuit to regulate the resonant power and output a transformed power. The resonant converter further has a primary output circuit and at least one secondary output circuit. The primary output circuit regulates the transformed power to become a primary output power. A resonant control unit captures a feedback signal from the primary output circuit and generates a resonant control signal. A phase shifting control unit receives the resonant control signal and regulate to become a phase shifting driving signal. The secondary output circuit is controlled by the phase shifting driving signal and provides a secondary output power.

The invention relates to a direct-driving wave power-generating and energy-storing device and a control method. The direct-driving wave power-generating and energy-storing device is characterized by comprising a direct-driving wave generator, an AC/DC (Alternating Current or Direct Current) converter, a DC/AC (Direct Current or Alternating Current) converter, a plurality of loads, two DC/DC (Direct Current or Direct Current) converters, a mixed energy storing system and a controller, wherein the mixed energy storing system comprises an ultra-capacitor bank and a storage battery pack; the direct-driving wave generator is used for converting the kinetic energy of waves to a low frequency alternating current and sending to the AC/DC converter; the AC/DC converter is used for converting the low frequency alternating current to a direct current and connect and connected with the input end of the DC/AC converter through a direct current bus; the output end of the DC/AC converter is connected with the loads; the direct current bus is respectively connected with one ends of the two DC/DC converters, the other end of one of the two DC/DC converters is connected with the capacitor bank, and the other end of the other of the two DC/DC converters is connected with the storage battery pack; and the controller is used for controlling the ultra-capacitor bank and the storage battery pack to regulate power flow so as to keep the balance between the output power of the direct-driving wave generator and the power of the loads. The invention can be widely applied to the process of converting the kinetic energy of sea water fluctuation to the electric energy.

A microbial fuel cell is provided according to embodiments of the present invention including electricigenic microbes containing at least about 0.075 milligrams of protein per square centimeter of the anode surface area. In particular embodiments, the electricigenic microbes are disposed on the anode such that at least about 90% of the portion of the anode surface area has a layer of electricigenic microbes, the layer greater than about 1 micron in thickness. This thickness is indicative of the layer including at least a first stratum of electricigenic microbes in direct contact with the anode and a second stratum of electricigenic microbes in direct contact with the first stratum such that the second stratum is in indirect contact with the anode.

A DC-DC power converter (100) that provides increased power density, reduced size, and reduced costs of manufacture. The DC-DC power converter (100) includes first and second input terminals (101, 102), a plurality of output terminals (116, 117), and at least one electrical element (108/109) connected to at least one of the first and second input terminals (101, 102). In the event a first voltage is applied across the first and second input terminals (101, 102), the electrical element (108/109) provides a second voltage having a value between the first voltage value and a reference voltage value. The DC-DC power converter (100) further includes a transformer (110) having a primary winding (111) and a secondary winding (112), and a switch assembly (103-107) operatively connected to the first input terminal (101), the second input terminal (102), the electrical element (108/109), and the transformer primary winding (111). In the event the first voltage is applied across the first and second input terminals (101, 102), the switch assembly (103-107) switchably applies the first, second, and reference voltages across the transformer primary winding (111) to generate at least one third voltage across the transformer secondary winding (112). The DC-DC power converter (100) further includes a rectifier (113) connected between the transformer secondary winding (112) and the output terminals (116, 117).

A magnetic flux switch type axial magnetic field permanent magnet brushless machine relates to a double air gap permanent magnet machine composed of two stators (1) and a rotor (2), wherein the stators (1) and a rotor (2) are arranged axially; the rotor (2) is clamped between two stators (1); the air gap with certain thickness is arranged between the stator (1) and the rotor (2); each stator (1) is composed of 12 U-shaped stator cores (3), 12 sector permanent magnets (4) and 12 coil2 (5); the U-shaped stator cores (3) and the sector permanent magnets (4) are put alternately to constitute the disc; the U-shaped stator core (3) and the permanent magnet (4) are respectively corresponding on the two stators (1), but the magnetizing directions of the two corresponding permanent magnets are opposite. The simple structure advances the operation reliability and the dynamic performance of the motor, meanwhile the axial size is smaller, which is suitable for the place requiring the thin mount, such as the robot, the computer peripherals, the electric automobiles and the wind electric power generation and the like.

A rechargeable lithium ion battery with high power density comprises a positive electrode; a negative electrode; and a non-aqueous electrolytic solution, in which the positive electrode includes a active material layer containing a positive electrode active material with the particle diameter of 5 μm or less and having the thickness at a range of 20 to 80 μm. Another rechargeable lithium ion battery with high power density comprises a positive electrode; a negative electrode; and a non-aqueous electrolytic solution, in which the positive electrode has two active material layers, each of which contains a positive electrode active material with a different diameter and has the thickness at a range of 20 to 30 μm.

According to the defect that the magnetic member of the existing LLC resonant converter has a larger volume, the invention provides a magnetic integrated converter suitable for LLC resonant series topology, pertaining to the direct current converter. The converter designs the transformer and inductances in the original circuit of the converter into an integrated magnetic member, the converter not only can decrease the volume of the magnetic members, but also allows the leakage inductance to be easy to control, wherein the leakage inductance are centralized at primary side. The converter includes a direct-current power supply, an LLC resonant transformer, a primary circuit and a secondary rectification circuit, the converter uses the integrated magnetic member as a magnetic integrated converter, wherein, the integrated magnetic member includes a couple of relative setup EE iron cores, the iron cores are respectively winded with a primary winding and a secondary winding, part of the primary winding and entire secondary winding are winded at the middle pole, the other part of the primary winding are winded at the left side pole or right side pole; the input end of the primary winding is connected to the primary circuit, the output end of the secondary winding is connected to the secondary rectification circuit.

The invention discloses an integrative propulsion and power generation device driven by axis-free contra rotating wheel flanges. The device comprises a guide pipe, and the guide pipe is internally provided with two rotating wheel assemblies which are axially and sequentially arranged along the guide pipe; each rotating wheel assembly comprises a stator, a rotor and a propeller which are sequentially arranged in the guide pipe in a sleeved mode, the stators are fixedly connected with the guide pipe, the two ends of each rotor are arranged on the guide pipe through bearings, the propellers rotate along with the rotors, and the rotating directions of the propellers in the two rotating wheel assemblies are opposite to each other. The integrative device is compact in structure, high in formed power density and thrust-weight ratio, long in service life, low in vibration noise and especially suitable for application to unmanned underwater vehicles, propulsion and power generation are conducted synchronously, the energy utilization rate is increased, and the stability is improved.

The modular conical stator pole provides an improved conical stator assembly on electrical machines. The improved conical stator pole assembly comprises a plurality of stator poles, each pole comprising an assembly having a coil secured on a soft magnetic composites (SMC) stator pole tooth by inserting a winding support through the open core of the coil and attaching a back iron and a stator face to either end of the winding support. Each stator pole having a parallelogram shaped cross section for forming a conical shaped rotor space when the stator poles are assembled having the back irons bearing against each other to space the coils apart and form a conical shaped outside profile of the stator pole assembly. The conical stator having a small end and a big end. The tooth comprising a winding support integrally molded with either the back iron or the face.

The invention discloses a wind-electricity variable pitch UPS system based on super-capacitors and the control method thereof. The UPS system comprises a super-capacitor group(10), a charge and discharge circuit(20), a control circuit(30) and a contactor(50). The super-capacitor group(10) is connected with the charge and discharge circuit(20) which is in connection with a DC generatrix(40)through the contactor(50); the control circuit(30), connected with the charge and discharge circuit(20), controls the operation of the charge and discharge circuit(20), and the whole system is connected or not with the DC generatrix(40) through the control of the contactor(50). The UPS system makes use of the control circuit(30) to control energy to flow in two ways between the super-capacitor group(10) and the DC generatrix(40), thus realizing continuous power supply. The UPS system is based on a simple principle and is flexible in structure; meanwhile, the high efficient charge and discharge control strategy can improve energy utilization ratio of the super-capacitor group and reduce installation content and cost of the system, thus greatly improving the technical performance and economic performance of the system.

The utility model discloses a moving coil permanent magnet linear motor having high power density. The utility model comprises a coil assembly, a coil assembly frame, an inner magnetic yoke, a permanent magnet, an outer magnetic yoke and other components; the coil assembly comprises a forward winding and a reverse winding; the coil assembly is fixed on the coil assembly frame, and is capable of making reciprocating linear motion in an air gap; the coil assembly frame is connected with the driven moving elements; the direction and the size of the current is regulated through an electric control system, and then the needed motion mode is realized. The permanent magnet group is arranged at one side or both sides of the coil assembly; the permanent magnet group alternately adopts permanent magnets with different magnetic directions along motion direction and forms a Halbach array. The utility model has the advantages that, the power density of the motor is improved obviously, which is 50% more than the power density of conventional linear motors; meanwhile, the utility model has better control characteristic. The utility model can be used as an executive element and applied to the situations where the volume and the mass of the linear motor need to be small, and the thrust and the accuracy of the linear motor need to be large; for example, the utility model can be applied to the electro-hydraulic proportional control field, the robot field or other fields.

The invention discloses a novel multiphase doubly salient permanent magnet motor. The novel multiphase doubly salient permanent magnet machine comprises a stator iron core, armature windings, permanent magnets and a rotor iron core, wherein the stator iron core is composed of a plurality of split stator iron cores. Each split stator iron core is provided with a plurality of stator salient poles which are distributed at certain intervals. A stator groove is formed by every two adjacent stator salient poles. Wire turns of the armature windings are embedded into the stator grooves. Every two adjacent wire turn sections in each armature winding are across more than three stator salient poles. An interval is formed between every two adjacent split stator iron core yoke portions to form a yoke portion groove. The permanent magnets are fixed in the yoke portion grooves. Rotors are of salient poles structures and are free of the permanent magnets and coil windings.

The invention discloses a coupling inductor applicable to a multi-phase interleaved parallel converter. A structure of the coupling conductor is mainly formed by combining backcoupling transformers consisting of two phases of windings and an energy storage inductor; for an n-phase interleaved parallel converter, the quantity of the backcoupling transformers is n-1 or n or n(n-1)/2, and the connection relation of the backcoupling transformers is a central type or a head-tail closure type or a two-two combination type respectively; and the energy storage inductor is serially connected with at least one phase of the winding in the backcoupling transformers, the winding quantity of the energy storage inductor is between 1 and n, and various phases of the windings of the energy storage inductor are independent from each other or are subjected to forward coupling. The coupling inductor ensures that an energy storage function and a filtering function are borne by the energy storage inductor and the backcoupling transformers respectively by splitting the energy storage function and the filtering function, can effectively avoid the intrinsic contradiction between the energy storage function and the filtering function in a multi-magnetic circuit magnetic core, further reduce the loss and volume of magnetic components, improve the power density, the conversion efficiency and the output dynamic performance of the converter, and is suitable for the multi-phase interleaved parallel converters.

A coil mutual-induction coupled linear switch reluctance motor comprises a primary pole and a secondary pole. The primary pole consists of iron cores which are laminated by a distributed multi-phase armature winding and a silicon steel sheet. The secondary pole is laminated by silicon steel sheets without winding. The primary pole and the secondary pole have salient pole structures. Pole numbers of the primary pole and the secondary pole and the rotation switch reluctance motor can be made into the forms such as 4/6 pole and 8/12 pole. The structure form can be one-sided or two-sided, can be a moving coil type or a moving iron core type. A motor winding is a distributed winding. The three-phase windings are mutually inducted and coupled. Two-phase excitation always exists in any working time. The reluctance motor solves the problems of low winding utilization rate and low motor power density of present linear switch reluctance motors and can be used as a motor also as a generator.

The present invention is relative to a engine apparatus comprising a combustion engine, a low pressure compressor connected to a high pressure turbine. The apparatus also comprises a low pressure turbine and a high pressure compressor. The engine apparatus according to the invention comprises an electrical torque converter comprising at least an electric generator connected so as to be driven by said low pressure turbine and a first electric motor connected so as to drive said high pressure compressor. The torque converter also comprises electronic conversion means suitable to convert the electric energy produce by said electric generator and to power supply and control at least said first electric motor.

The invention provides a stator used for a motor, the motor and a ventilation cooling method of the motor. The stator used for the motor comprises concentrated windings and at least two wedge blocks arranged at the gaps between the adjacent concentrated windings. The at least two wedge blocks are distributed on the concentrated windings in a staggered mode to form a first ventilation path. According to the stator used for the motor, the motor and the ventilation cooling method of the motor, the concentrated windings can be cooled effectively, the concentrated windings are effectively constrained in the circumferential direction through the at least two wedge blocks, the service life of the motor is further prolonged, and the reliability of the motor is improved.

A power converter utilizes one or more nonlinear composite film capacitors constructed solely of polymer anti-ferroelectric (AFE) particle composites and configured as DC-link bus capacitors providing an energy buffer to reduce DC-link voltage ripple.

A converter coupled to a DC voltage input and connectable to a load, includes a signal responsive switch coupled between a first circuit point and a second circuit point. Current flow is directed by the switch, when in a closed state, to the second circuit point to bypass the load. A regulator circuit has an output coupled to a control input of the switch. The regulator circuit has a first input for receiving a sensed load parameter, a second input for receiving a sensed current level signal at the second circuit point when the switch is in its closed state, and a third input for receiving a sensed current level signal at the second circuit point, measured directly, when the switch is in an open state. A fixed minimum time is set for the switch to be in the open state. The third input inhibits re-closing of the switch, providing current limit protection for the switch.

The invention relates to a switched reluctance motor with a dual-rotor structure, and belongs to the technical field of switched reluctance motors. The switched reluctance motor with the dual-rotor structure comprises a left end cover, a right end cover, an enclosure, a stator core, an inner-layer winding, an outer-layer winding, an outer rotor core, an inner rotor core, a bearing A, a bearing B, a main shaft and a flange. A group consisting of the outer rotor core, outer-layer salient poles of a stator and windings of the outer-layer salient poles of the stator, and a group consisting of the inner rotor core, inner-layer salient poles of the rotor and windings of the inner-layer salient poles of the stator simultaneously work equivalent to an outer-rotor switched reluctance motor and an ordinary switched reluctance motor respectively, and the torque of two rotors is superposed to obtain output torque; and by the structure, the space of the motor is fully utilized, and compared with that of the conventional switched reluctance motor with the same rotating speed and the same volume, power density is greatly increased.

The invention provides a preparation method for a biomass base active carbon electrode material and relates to the field of preparation of electrode materials. The method includes steps of oxidizationof biomass material; mixed solution dipping of organic amine and an alkali compound; carbonization; mixing with an activator; activation, wherein the activation temperature is 500 to 1000 DEG C, thepreferred temperature is 500 to 800 DEG C and the optimal temperature is 500 to 650 DEG C; cleaning and drying through which active carbon material used for an electrode of a super capacitor is acquired; and electric performance testing. The product prepared in the invention is high in energy density and long in service life when being applied to the super capacitor.

The invention discloses a proton exchange membrane used for a direct methanol fuel cell and a preparation method thereof. The method comprises: first, polyether-ether-ketone is added into concentrated sulfuric acid for sulfonation reaction to obtain sulfonating polyether-ether-ketone; ball milling is carried out on the sulfonating polyether-ether-ketone, inorganic cross linker, silane coupling agent and organic solvent to obtain suspending liquid; the mass volume ratio between the sulfonating polyether-ether-ketone and the organic solvent is 1/5g/ml-1/15g/ml; the mass ratio between the silane coupling agent and the inorganic cross linker is 1:5-10; the mass ratio between the sulfonating polyether-ether-ketone and the inorganic cross linker is 5-20:1; finally, the mixture solution of the sulfonating polyether-ether-ketone, the inorganic cross linker and proton conductor are made into membrane which is then dried for demoulding, and the proton exchange membrane used for the direct methanol fuel cell can be obtained. The membrane features good methanol diffusion resistance, low cost, high proton conductivity and excellent water-resistant swelling capacity at the higher temperature. The preparation method is simpler as well as lower in raw material price and production cost.

The invention relates to a double-equal pole double-section stator/rotor reluctance generator, comprising two sections of stators and rotors of a salient pole structure or a non-salient-pole structure formed by laminating silicon-steel plates. A stator salient pole is provided with armature concentrated windings or layer windings; the windings are connected in series or in parallel according to the N-N polarity of the armature windings to form a phase, and the windings are connected in series or in parallel according to the S-S polarity of the armature windings to form the other phase; the rotors are equipped with rotating magnetic poles with the same pole number with the stators, and the adjacent pole windings of the rotors are connected in series or in parallel to form a plurality of N and S groups; the rotors can adopt excitation magnetic poles and permanent magnetic poles in different forms and permanent magnetic and electro-magnetic mixed poles, and a rotor excitation device is arranged on a motor shaft; each rotor can be divided into an inner rotor and an outer rotor; and the armature windings can be arranged on the stators or the rotors. In the invention, by adopting an equal-pole-number stator/rotor technology and series/parallel connection dynamic combination of the windings, output voltage can be regulated conveniently, the utilization ratio of the windings is improved, and power density and efficiency of the generator are enhanced.

The invention discloses a totally enclosed motor for achieving separate cooling of a stator and a rotor by a dual-channel fan. The dual-channel fan 9 with a unique design is adopted and matched with a motor structure, so that a combined cooling mode of enclosed ventilation cooling of the stator and open ventilation cooling of the rotor of a three-phase asynchronous motor is achieved. By the combined cooling mode, the stator insulating reliability and the rotor cooling capacity are ensured; and the motor efficiency is improved. The dual-channel fan 9 can play roles of two fans, so that the motor structure is compact. Fan blades of the dual-channel fan are divided into two groups 9c and 9f, and are in staggered distribution in the circumference. Air ducts 5a, 10a, 3a, 9a, 9c, 9b and 6a form independent rotor cooling air ducts; the air ducts 6b, 9d, 9f, 9e and 2a form independent stator cooling air ducts; a convex edge 5b and a toothed plate 11 form a labyrinth seal; a fan excircle 9g and the convex edges 6d and 6e are in small-gap fit; and a stator space is isolated from a rotor space.

The invention relates to a high-speed electric machine electromagnetism structure for an air compressor. The high-speed electric machine electromagnetism structure for the air compressor comprises a stator core, a stator winding which is arranged on the stator core, a rotor core and a permanent magnet which is clamped on the surface of the rotor core; a plurality of stator grooves are uniformly formed in the circumference of the stator core; the stator winding is arranged inside the stator grooves in a connecting mode of three-layer low harmonic wave concentric winding; a plurality of wedge-shaped grooves are uniformly distributed along the circumference of the surface of the rotor core; a wedge-shaped arm is arranged between the adjacent two wedge-shaped grooves; air magnetic separation holes which are used for improving the gap flux density amplitude are formed in the wedge-shaped arm; permanent magnets are clamped in the wedge-shaped grooves. Compared with the prior art, the high-speed electric machine electromagnetism structure for the air compressor has the advantages of being compact in integral structure, high in rotation speed, high in mechanical intensity, small in harmonic loss and the like.

The invention discloses a SiC JFET (junction type field effect transistor) device for integrating a schottky diode. A primitive cell structure of the SiC JFET device for integrating the schottky diode in an active region from bottom to top successively comprises a drain electrode, a SiC substrate, a buffer layer, an n-drifting layer, two p+ trap layers arranged in bilateral symmetry, an n channel layer, and two p+ regions arranged in bilateral symmetry on the two sides of the n channel layer; a p+ region, a n++ region, the p+ region, the n++ region and another p+ region are successively arranged from left to right in symmetry; a source electrode, a grid electrode, a schottky contact, another grid electrode and another source electrode are successively arranged from left to right in symmetry; the source electrode is arranged on the p+ region and the n++ region, adjacent to the left and right sides of the primitive cell structure, the grid electrode is arranged on the middle p+ region on the left and right sides of the primitive cell structure, the schottky contact is arranged on a partial middle n region of the primitive cell structure in the active region, and no schottky contact is arranged on other parts of the n region of the primitive cell structure. The SiC JFET device that integrates JFET and V JFET into one, and integrates a schottky diode is disclosed. In addition, a making method is provided.

The invention provides an offshore large direct-drive switch reluctance wind driven generator power converter and a system of the converter. The converter is composed of a switch reluctance wind turbine, a power converter body, a DC/DC converter body and a system controller. The switch reluctance wind turbine is connected with the power converter body. The power converter body is connected with the DC/DC converter body. Output of the DC/DC converter body is connected with output of a DC/DC converter body of the other switch reluctance wind driven generator power converter system in series or parallel and then outputs electric energy to the shore through a direct-current submarine cable. The system controller is connected with the power converter body and connected with the DC/DC converter body. The switch reluctance wind turbine is connected with the system controller. According to the system, two-phase windings of a four-phase switch reluctance generator can work at the same time, exciting voltage is adjustable, the function of outputting direct-current voltage and adjusting boost can be achieved, the power density and the controllable flexibility are improved, and the power converter is suitable for the field of offshore large wind power plants.

The invention relates to the technical field of crystal silicon photovoltaic cells, in particular to a processing method for processing rectangular photovoltaic cell silicon slices through columnar crystal silicon rods. The processing method comprises the steps of firstly, determining and processing of columnar faces of the silicon rods, secondly, silicon rod cutoff, thirdly, slicing, fourthly, treatment of irregular sides and corners, and fifthly, chamfering and slicing. According to the processing method, after the crystal orientation of the needed crystal silicon slices is determined, a longitudinal cutting technology is adopted for obtaining the crystal silicon slices of the needed size and crystal orientation. The processing method has the advantages that compared with a traditional transverse slicing method, the same rectangular silicon slices are processed, the effective utilization rate of the cylindrical crystal silicon rods can be increased, and under the condition of the same silicon rod utilization rate, the more regular rectangular silicon slices can be processed out; and the silicon slices processed through the method can adjust the voltage, current and power levels of a photovoltaic module in a standardized manner. The photovoltaic module formed by the rectangular silicon slices has higher power density and lower unit cost than the existing technology.

The invention provides a preparation method of a nitrogen-doped graphene electrode, which comprises the following steps: acquiring a graphene oxide suspension; mixing the graphene oxide suspension with a metal salt solution to obtain an electrolyte; putting at least one pair of electrode pieces connected with direct current into the electrolyte, switching on the direct current to carry out electrophoresis so as to obtain electrode pieces with graphene oxide deposited on the surface, and drying under vacuum conditions; reacting the graphene oxide deposited on the surface of the dried electrode pieces with ammonia gas to carry out nitrogen doping reaction, thereby obtaining a nitrogen-doped graphene electrode precursor; and in a hydrogen protective atmosphere, carrying out reduction reaction on the nitrogen-doped graphene electrode precursor and hydrogen to obtain the low-oxygen-content graphene-doped graphene electrode. The preparation method provided by the invention has the advantages of simple technique, high efficiency and low cost; and the nitrogen-doped graphene electrode prepared by the method has the advantages of low equivalent series resistance, high electric conductivity and low oxygen content in the nitrogen-doped graphene in the nitrogen-doped graphene electrode.

The invention discloses a nanometer carbon-lead super capacitor battery, which comprises electrodes, wherein the electrodes are made of a carbon nanomaterial and a foam lead composite material; the carbon nanomaterial and the foam lead composite material are prepared by adopting an electrolytic deposition method; and the electrolytic deposition method comprises the following steps: preparing an electrolytic deposition solution; adding a carbon nanomaterial into the electrolytic deposition solution prepared in the step (1); and performing electrolytic deposition to obtain the carbon nanomaterial and the foam lead composite material. According to the nanometer carbon-lead super capacitor battery disclosed by the invention, a lead-acid battery is combined with a super capacitor, so that high energy storage density and high power density are realized simultaneously; high charging and discharging performances are achieved, and the charging speed of the battery is the same as the discharging speed in an unsaturated charging running mode; a carbon material can be used for preventing the phenomenon of sulfation on the cathode, so that a past failure factor of the battery is improved, and the service life of the battery is prolonged; and the nanometer carbon-lead super capacitor battery has very high safety performance, and is an environment-friendly safe battery.

The invention provides a motor rotor, a permanent magnet motor and a compressor. The motor rotor comprises a rotor iron core of which the end surface is provided with multiple sets of accommodating slots along the circumferential direction of the rotor iron core; and multiple permanent magnets which are correspondingly embedded in multiple sets of accommodating slots, and the permanent magnets in all sets of accommodating slots form magnetic poles, wherein the number of the magnetic poles is greater than or equal to eight and less than or equal to twelve, the distance between the two ends of the magnetic poles is L, the peripheral diameter of the rotor iron core is D1, and 0.18xD1<=L<=0.28xD1. With application of the technical scheme, the higher power density can be realized by limiting the dimension relationship between the peripheral diameter of the rotor iron core and the distance of the two ends of the magnetic poles with cooperation of increasing of the number of the magnetic poles; besides, the dimension of the motor rotor can be reduced by limiting the number of the magnetic poles so as to realize miniaturization of the motor.