116results about How to "Increased freedom of control" patented technology

The invention provides a six-phase flux switching type permanent magnet motor which comprises stators, rotors and a rotating shaft, wherein each stator adopts a permanent magnet double salient structure, that is, the permanent magnet, the stator core and the armature winding are arranged on each stator, the stator core is assembled by an U-magnetic core and each permanent magnet embedded in the magnetic core, and the permanent magnets are of tangential alternate magnetization; the armature winding is of six-phase armature winding arranged on the stator, the six-phase armature winding adopts centralization coils, and the rotors are made of permeability magnetic material; the magnetizing directions of the permanent magnets are of the tangential of the stator circle, and the magnetizing directions of two adjacent permanent magnets are opposite to each other; the number of the armature coil and the stator groove is even number times of the phase number; and each phase 2n coils winding, and n coils are distributed at the two ends of the diameter of the stator circle respectively. And two three-phrase winding can conduct independent power supplying and generating.

The invention relates to a method for intelligently switching mobile phone scene modes, which comprises the following steps that when the scene mode of a mobile phone is in a silent mode, and times of new happened events are over the set times within set unit time, a mobile phone incoming call reminding mode is intelligently switched into a promoting tone reminding setting mode preset by a user, and corresponding response is carried out according to the promoting tone setting preset by the user; and when the user receives a new event, a system automatically recovers all new event promoting modes into a silent tone reminding mode which is initially preset by the user. In the embodiment of invention, even in an emergent condition, the mobile phone has an intelligent switching function, the condition that the user misses the important incoming calls can be reduced, the requirements of the mobile phone users can be better met, and the practicability of the mobile phone can be improved.

The invention relates to an application method for a subscriber identity module (SIM) card of a double-card single-dialing mobile phone. The application method comprises the following steps of: configuring the application of double cards when a guide of double-card arrangement appears during first application of the mobile phone or detection of a new SIM card so as to meet individual demands of a user; defaulting the SIM card used by a communication event when a new communication event is performed by the user; highlighting a signal bar of the SIN card in a status bar; and simultaneously appearing the options of the two SIM cards in menu for the user to select. By implementation of the invention, the functions demanded by the application of the two cards can be realized so as to conveniently meet the user requirement.

The invention discloses a double-active bridge DC / DC converter full range soft switch control method based on frequency regulation. The double-active bridge DC / DC converter full range soft switch control method adds switch frequency regulation on the basis of conventional dual-phase-shift control, expands a soft switch working scope of a converter, enables the converter to realize zero voltage switching in a full load scope, reduces switch loss of the converter and improves efficiency of the dual-active bridge. The double-active bridge DC / DC converter full range soft switch control method based on the frequency regulation does not need to change the structure of a regular dual-active bridge, does not need to add a sensor, and saves cost. Besides, the double-active bridge DC / DC converter full range soft switch control method also increases freedom of control of the dual-active bridge circuit, makes control more flexible and can be applied to the high frequency isolation switch power supply.

The invention provides a power distribution optimized scheduling method of a motor train neighborhood sub-system, and the method comprises the following steps that (1) a single compartment of a motor train unit serves as a local sub-system, and local sub-system models of the motor train unit are respectively built according to different stress on the head compartment, a tail compartment and compartments between the head and the tail of the motor train unit; (2) a motor train neighborhood sub-system model is built according to the local sub-system model of the motor train unit; (3) constraint conditions during the operation process of the motor train unit are established according to the resultant force on each compartment; (4) an optimized and controlled target function is determined according to the mutual acting force among the compartments in the motor train neighborhood sub-system model, a prediction time domain and a control time domain; and (5) the target function is solved under the constraint conditions to obtain the optimized scheduling of power distribution during the operation process of the motor train unit. According to the power distribution optimized scheduling method of the motor train neighborhood sub-system, the power distribution prediction control of the high-speed motor train unit can be realized, so that the control freedom of each compartment is higher, the response is quicker, and the power distribution efficiency is improved.

The invention relates to a digital hydraulic control valve, and belongs to the technical field of hydraulic driving and controlling. The digital hydraulic control valve comprises five groups of flow control units which are same in structure. Each flow control unit is composed of connecting of eight sets of electro-magnetic switch valves with throttling openings in parallel. The drift diameters of the electro-magnetic switch valves are totally same. The throttling areas of the throttling openings are coded by adopting the Fibonacci sequence. By controlling the combining state of electro-magnets of the electro-magnetic switch valves, the control over the output flow (the size and the direction) and the pressure can be achieved. The resolution ratio and the maximum flow of the valves can be confirmed according to the actual needs. The digital hydraulic control valve is formed by the regular electro-magnetic switch valves and the throttling openings, the structure is simple, the cost is low, the advantages of the switch valves are continued, the reliability is high, the anti-pollution capacity is strong, the all-digital control is achieved, multiple control modes and working modes are achieved, the control freedom degree is high, the flexibility is high, the fault diagnosis is easy to carry out, and the great fault-tolerant capability is achieved.

The invention relates to a method for intelligently reminding the birthday of a mobile phone contact, comprising the following steps: adding an intelligent birthday reminding module in a mobile phone system, wherein the intelligent birthday reminding module is associated with a telephone book module, a calendar function module and an alarm clock module. When the user finishes setting an intelligent birthday reminding function, the mobile phone reminds the user if the mobile phone contact birthday comes or is to come, so that the mobile phone user omits abundant repetitive work to save a large amount of time, and the method is more convenient and humanized.

The invention relates to an automatic speed changer electric hydraulic cooling lubrication system. An oil inlet of an oil absorbing filter of the system is connected with an oil storage tank, and an oil outlet of the oil absorbing filter is connected with an oil suction port of an electric hydraulic pump. An oil outlet of the electric hydraulic pump is connected with an electric hydraulic pump outlet filter and an oil port in one end of an loading valve in parallel, the other end of the electric hydraulic pump outlet filter is connected with the inlet end of a cooler, and the outlet end of thecooler is connected with a plurality of clutch proportion flow control valves and the inlet end of a shaft tooth flow adjusting device in parallel; an oil port in the other end of the unloading valveis connected with the oil storage tank, and a one-way valve is connected to the outlet of the electric hydraulic pump and the outlet end of the cooler in parallel; the other ends of the clutch proportion flow control valves are connected with clutches; and the other end of the shaft tooth flow adjusting device is led to a shaft tooth cooling lubricating oil spraying pipe. The automatic speed changer electric hydraulic cooling lubrication system does not contain pressure and flow sensors, the control process can be finished without obtaining real-time system pressure and flow signals, and theoccupied space and cost of the system can be saved.

The invention discloses an LCC resonant converter PWM phase shift mixed control and efficiency optimization method. The method comprises the following steps: carrying out sampling on output voltage of a converter, obtaining voltage difference between an output voltage sample value and a reference value and serving the voltage difference as the input of a voltage regulator, and obtaining an output value c; carrying out sampling on resonance current of the converter, and carrying out optimization algorithm to obtain two coefficients k1 and k2; carrying out calculation and correction on the output instruction value c of the voltage regulator through the coefficients k1 and k2 to obtain two instruction values, that is, phase shifting angle theta and duty ratio d, of the PWM phase shift mixed control method; and inputting the phase shifting angle and the duty ratio instruction values to a PWM phase shift mixed modulator to obtain driving signals of four switching tubes at a primary side of the resonant converter. The method improves control freedom degree of the converter; and under the condition of maintaining specific output power invariant and ensuring ZVS realization, the resonance current is allowed to be minimum by adjusting the coefficients and changing combination of control variables, and efficiency of the converter is improved.

The invention discloses a switching reluctance motor driving topology based on a three-level inverter. The new topological structure is formed by combining windings of a switching reluctance motor with the three-level inverter, and sharing a bridge arm of the three-level inverter by two phase windings of the switching reluctance motor while three phase windings are connected in an end to end manner. Considering that torque ripples are mainly generated in a phase commutation region, the traditional typology has large ripples since the operating modes are few. The typology provided by the invention has 9 different modes in single-phase operation, has 27 combined modes in a two-phase overlapping region, has different operating states, can select the optimal state according to needs in correspondence to different phase voltages, changes torque waveforms, greatly improves control freedom degree, reduces torque ripple, and increases torque. The switching reluctance motor driving mechanism is advantageous in providing a five level circuit, so that each phase winding has good applicability and flexibility in the aspects of high speed, low speed, excitation and demagnetization, effectively reduces switching frequency, reduces switching loss, increases output torque of the switching reluctance motor, and smoothes the torque ripples.

The invention discloses a twin-stage type matrix converter with direct-current excitation regulation and voltage frequency transformation, comprising a three-phase bridge type structure formed by two-way power switches, a buffer circuit, a five-bridge-arm structure formed by one-way power switch tubes and two equivalent direct current buses, wherein the three-phase bridge type structure, the buffer circuit and the five-bridge-arm structure are connected between the two equivalent direct current buses in parallel. The invention has the advantages of small volume, light weight, compact structure, little harmonic content and high efficiency.

The invention discloses an expansion control set-based forecast flux linkage control method of a permanent-magnet synchronous motor. The expansion control set-based forecast flux linkage control method comprises the steps of performing mathematical modeling on the permanent-magnet synchronous motor; acquiring a virtual voltage vector of a terminal point arranged on a boundary of a space voltage vector hexagonal plane with regard to a stator voltage vector in a mathematical model, wherein the virtual voltage vector and a basic voltage vector form an expansion control set; acquiring an expansioncontrol set-based forecast flux linkage control model, employing a stator flux linkage vector as a control variable, and building a cost function according to influence of different control sets on stator flux linkage track within a sampling period, wherein an average value of the stator flux linkage reference track and actual track error which are calculated within the sampling period by an integral method is quantized by the cost function; determining optimal sector by cost function optimal dissolving, seeking optimal expansion voltage vector in the optimal sector, and performing amplitudeoptimization on the optimal expansion voltage vector.

The invention provides a digital hydraulic actuator system for composite speed adjusting of a closed pump valve and a control method of the digital hydraulic actuator system. The system comprises a servo motor, a two-way quantitative hydraulic pump, high-speed switching valves, an energy accumulator, a hydraulic cylinder, pressure protection valves, a pressure sensor, a displacement sensor, a speed encoder, a motion controller and other elements. During work, the servo motor drives the two-way quantitative hydraulic pump to work, hydraulic cylinder reversing and system volume speed adjusting can be achieved, the high-speed switching valves can adjust and control the flow in the system, composite speed adjusting of the pump valve is achieved, the pressure protection valves are used for setting the safety pressure of the system and the maximum working pressure of the hydraulic cylinder, the energy accumulator achieves oil suction and drainage by storing and releasing oil, the characteristic that the flow of an asymmetric cylinder is not balanced is overcome, the high-speed switching valves on an oil inflow way in the system can be used as load holding valves in a switched-off state,the hydraulic cylinder can be positioned, and the motion controller can control actions of all the elements after processing signals. The digital hydraulic actuator system for composite speed adjusting of the closed pump valve and the control method of the digital hydraulic actuator system have the beneficial effects of being flexible in control, high in precision, rapid in response, remarkable inenergy-saving effect, high in safety and the like.

The invention provides a digital electro-hydrostatic actuator system. The system comprises a servo motor and a hydraulic pump, wherein the servo motor is connected with the hydraulic pump; a high-speed switch valve bank which is connected with the hydraulic pump; the hydraulic cylinder which is connected with the high-speed switch valve bank, wherein a piston rod of the hydraulic cylinder is connected with a load; a signal processor which is used for receiving signals and parameters of the sensor; and a system state control unit which is connected with the signal processor and is used for controlling the actions of the servo motor and the high-speed switch valve bank according to the feedback signal or parameter information so as to form differential control and load independent control. The system is higher in control freedom degree, higher in control precision, energy-saving and reliable in action.

The invention relates to an intelligent switching method for new event reminding modes of a wireless charging state of a mobile phone. The method comprises the following steps of: S1, generating new events, wherein the new events comprise incoming calls, incoming information, alarm clock arrival time and the like; S2, detecting whether the mobile phone is wirelessly charged through a system; and S3, if so, marking the zone bit of a special register as '1', and making response according to the reminding mode preset by a user, otherwise, marking the zone bit of the special register as '0', and making response according to the reminding mode initially set by the user. By implementing the method disclosed by the invention, the trouble and obsession brought to the mobile phone user by wireless charging accidental interruption of the mobile phone when the new events of the mobile phone happen can be reduced.

The invention discloses a combined type digital valve with a loading port independently controlled and a method thereof. The combined type digital valve comprises a valve block, a plurality of switch valves, a loading port pressure sensor A and a loading port pressure sensor B; a threaded hole is formed in each of the four surfaces of the valve block, the threaded hole P and the threaded hole T are arranged oppositely, and the threaded hole A and the threaded hole B are arranged oppositely. According to the valve, by combining and applying the high-speed switch valves, when one cartridge valve is broken down, users just need to replace the cartridge valve broken down, there is no need to replace the whole combination unit of the digital valve, and therefore the maintenance cost and the replacement cost can be lowered, and the production cost can be greatly lowered; the loading port is independently controlled, and therefore the system control freedom degree is improved, and further improvements of the control performance and the energy conservation performance of engineering machinery become possible. By combining and applying the high-speed switch valves, when one or more cartridge valves are broken down, the other cartridge valves can still work normally, and therefore the influence to controlled objects is lowered to the minimum level.

The invention discloses a full-duty-cycle current-sharing control method based on an interleaved parallel Boost converter, thereby solving a non-current sharing problem of the capacitor series interleaved Boost converter in a full duty cycle range. According to the control method, charging time and discharge time of an intermediate storage capacitor are adjusted based on a capacitance charge balance principle and thus the inductor current is changed accordingly, so that two-phase inductor current sharing is realized. According to the method, no additional current sensor needs to be added and no additional control free amount needs to be added; and only the duty ratio of one certain phase of current needs to be changed based on the original circuit; current sharing of the converter in the full duty cycle range is realized without sampling feedback; and the double voltage characteristic of the conventional Boost converter is kept, so that the circuit control is simplified and the circuitstability and application range is extended. The method is a high-performance and low-cost solution.

The invention discloses a dominant dynamic elimination control system and control method for voltage-controlled inverters, which belong to the technical field of control of distributed power supply grid-connected inverters. The method includes the following steps: a time-domain state space model of a three-phase inverter in an alpha-beta coordinate system is established with complex variables; a compact and concise state feedback control structure based on complex variables is designed, and state feedback and feed-forward control of the system are separated to enable the closed-loop pole and the closed-loop zero of the system to be configured independently; the closed-loop pole position of the system is optimized by state feedback control in order to optimize the motion mode of state variables; and the closed-loop zero is used to offset the dominant closed-loop pole, so as to eliminate the slow dynamic process of the system. Because complex variables are introduced, the closed-loop zero of the system can be configured arbitrarily in the whole complex plane, the closed-loop zero can coincide with the dominant closed-loop pole, the dominant slow dynamic process introduced by a controller can be eliminated, and the dynamic response speed of the system can be improved.

The invention discloses an isolated double-full-bridge ANPC three-level DC / DC converter which comprises two full-bridge ANPCs, a transformer and an inductor. Each full-bridge ANPC is composed of two voltage dividing capacitors and two half-bridge ANPCs. The voltage dividing capacitors are connected to Vdc in series, the voltage of each voltage dividing capacitor is Vdc / 2, and the half-bridge ANPCsconnect the midpoint of bridge arms of series-connected switching tubes to the series midpoint of the two DC voltage dividing capacitors, so that the voltage stress borne by the switching tube in each half-bridge ANPC is Vdc / 2. Each half-bridge ANPC can output three levels, namely, Vdc / 2, 0 and -Vdc / 2. The output level of each full-bridge ANPC is determined by the difference value of the output levels of the two half-bridge ANPCs, and five levels of Vdc, Vdc / 2, 0, -Vdc / 2 and -Vdc can be output. The two full-bridge ANPC active bridges can output five levels to enable the voltage at the two ends of the inductor to have nine levels. According to the invention, the AC voltage series is increased, and a higher degree of control freedom is obtained.

The invention provides a vehicle full fly-by-wire manipulation system, and belongs to the technical field of ground vehicle control systems. The vehicle full fly-by-wire manipulation system comprisesa man-machine interactive manipulation interface, a man-machine interactive manipulation interface feedback port, an upper computer, sensors and an actuating mechanism. The man-machine interactive manipulation interface comprises an electronic mode rod, an electronic accelerator and brake pedal assembly, an electronic steering wheel and a graphic display. The vehicle full fly-by-wire manipulationsystem has the advantages that the electronic mode rod is used for selecting driving modes, mechanical signals of the electronic steering wheel and pedals are converted into electric signals by the man-machine interactive manipulation interface, the driving modes are selected, accordingly, the electric signals can be parsed in the upper computer according to set laws to obtain corresponding targetcontrol variables, the control variables can be transmitted to the actuating mechanism and can be converted into mechanical output, and corresponding manipulation experience can be sequentially fed to a driver via the man-machine interactive manipulation interface feedback port and interfaces of the man-machine interactive manipulation interface feedback port; mechanical transmission equipment between a common vehicle manipulation interface and an existing actuating mechanism is replaced by electric signal processing, accordingly, the manipulation flexibility and safety can be improved, the integral vehicle weight can be reduced, and the complexity can be lowered.

The present invention discloses an optical path control system and an optical module. The system comprises a focusing lens and an optical path acting assembly; the focusing lens is used for converging light beams passing through the focusing lens; the optical path acting assembly is used for controlling the transmission direction of the light beams; and when a plurality of incident light beams pass through the optical path acting assembly and the focusing lens sequentially, the optical path acting assembly converges the plurality of incident light beams, and the focusing lens converges each incident light beam into a light spot. According to the optical path control system and the optical module of the present invention, the intervals of the light beams can be adjusted through the functions of the optical path acting assembly and the focusing lens, and therefore, the structure of the optical path control system is simple, the number of optical path devices is reduced, the size of the whole optical path control system is greatly reduced, and thereby, the size of the whole optical module can be reduced; the relative positions of the focusing lens and the optical path acting assembly can be fixed easily, and therefore, the relative accuracy of focusing positions is improved; and the optical path acting assembly can be designed independently to realize independent control on the light beams, and the transmission direction and focusing point of each light beam can be independently controlled, and therefore, the degree of adjustment freedom is high.

The invention discloses a gas exhaust valve drive system with stroke capable of being compensated and regulated. The gas exhaust valve drive system comprises a low-voltage servo drive oil supply device, a stroke compensating and regulating module, a high-voltage common rail unit, a control implementation unit, a gas exhaust valve and a drive device thereof, wherein the stroke of a valve rod of the gas exhaust valve is adjustable; oil supply pressure of the low-voltage servo drive oil supply device can be flexibly regulated according to needs by virtue of a pressure compensating valve; the stroke compensating and regulating module is used for flexibly regulating the valve rod stoke and keeping the valve rod stroke at a required position according to a valve rod displacement or air cylinder pressure feedback signal; meanwhile, valve rod closing buffer time is flexibly regulated by virtue of a variable throttle at an outlet of a proportional flow valve, so that impact force when the valve rod is dropped is reduced; and opening and closing of the valve rod are controlled by the high-voltage common rail unit and the control implementation unit. According to the gas exhaust valve drive system, flexible adjustment of valve rod stroke, opening, buffering and closing time is realized, impact force when the valve rod is dropped is effectively reduced, control freedom of a diesel engine gas exhaust system is improved, gas exhaust consistency of each cylinder is improved, and the service life of the system is prolonged, and therefore, the gas exhaust valve drive system is suitable for internal combustion engines with different cylinder diameters, different performances and different exhaust needs.

The invention discloses an electro-hydraulic hybrid drive vehicle power system comprising an electronic control unit, motors, a battery pack, a first hydraulic energy accumulator, a variable hydraulicmotor, a clutch, a plurality of sets of wheels and a drive axle. The battery pack is connected with the two motors, the output ends of the two motors are connected with two wheel in one set respectively, the first hydraulic energy accumulator is connected with an oil transportation inlet of the variable hydraulic motor, and the first hydraulic energy accumulator is used for storing recycled braking energy and auxiliary driving and braking; the variable hydraulic motor is connected with the drive axle through the clutch to drive the two wheels in another set, the electronic control unit is respectively connected with the motor, the first hydraulic energy accumulator, the variable hydraulic motor and the clutch, the electronic control unit controls the running working condition of the motorand the displacement of the variable hydraulic motor, the on-off of the first hydraulic energy accumulator and the engagement or separation of the clutch, and the battery pack supplies power to the motor and the electronic control unit. The electro-hydraulic hybrid drive vehicle power system has the advantages of infinitely variable speed and four-wheel driving, energy saving and enhancement of endurance.

The invention belongs to the field of high-altitude aircraft air pressure simulation device research, and specifically relates to a dynamic negative pressure servo control system based on high-speed switch valves. The system includes a controlled containing cavity, an independent air inflation unit, an air exhaust unit and a controller, an air inflation high-speed switch valve is arranged on the air inflation unit, and more than three air exhaust high-speed switch valves are arranged on the air exhaust unit. The invention also discloses a dynamic negative pressure servo control method based onhigh-speed switch valves. Through independent control of the air inflation unit and the air exhaust unit, configuration of one high-speed switch valve on the air inflation unit and configuration of more than three high-speed switch valves on the air exhaust unit, the problems of high price and large volume of an existing proportional valve / servo valve can be correspondingly effectively solved, serious asymmetry of air exhaust and air inflation which occurs in a negative pressure situation is avoided, dynamic negative pressure servo control can be realized sensitively and accurately, and the dynamic negative pressure servo control system and method based on high-speed switch valves have the advantages of simple structure, low cost and the like, and thus are particularly suitable for spacecraft air pressure simulation equipment.

The invention discloses a decoupling control method and device for input-series and output-parallel DAB converters. The inputs of N identical DAB converters are connected in series and the outputs areconnected in parallel, and a first phase shifting ratio Di and a second phase shifting ratio De are obtained through input voltage sharing control and output voltage control respectively; the controlsequence between switch tube drive impulse sequences is obtained through phase shifting control according to the first phase shifting ratio Di and the second phase shifting ratio De; and switch control signals with a control sequence are input to the control ends of switching devices Q1-Q4 on a primary side H1 of a transformer of each DAB converter and to the control ends of switching devices Q5-Q8 on a secondary side H2 of the transformer of each DAB converter, in order to complete the control process. According to the decoupling control method for input-series and output-parallel DAB converters provided by the invention, the input voltage sharing and the output voltage are kept constant by using the two phase shifting control degrees of freedom of double phase shifting control of DAB converters. Compared with the traditional single phase shifting control, by increasing the number of control degrees of freedom, complete decoupling between the output voltage control and the input voltage sharing control is realized.

The invention discloses a bidirectional DC / DC converter based on an isolated full-bridge ANPC and an H bridge. The converter comprises a full-bridge ANPC and an inductor which are connected with one side of a transformer, wherein an H bridge circuit is connected with the other side of the transformer, the full-bridge ANPC can output five levels at most, the H-bridge circuit can output three levelsat most, a full-bridge ANPC active bridge is composed of two voltage-dividing capacitors and two half-bridge ANPC three-level circuits, the two voltage-dividing capacitors are connected in series with a bus voltage Vdc, a voltage of each voltage-dividing capacitor is Vdc / 2, the half-bridge ANPC connects a midpoint of a bridge arm of a series switch tube to a series midpoint of the two voltage-dividing capacitors, so the voltage stress borne by the switch tube of each half-bridge ANPC is Vdc / 2; each half-bridge ANPC active bridge can output three levels of Vdc / 2, 0 and-Vdc / 2, the output levelof the full-bridge ANPC is determined by a difference value of the output levels of the two half-bridge ANPCs, and five levels of Vdc, Vdc / 2, 0,-Vdc / 2 and-Vdc can be outputted. The converter can be adapted to application occasions with high voltage conversion ratios.

The invention discloses a light load operation method of an LLC resonant converter. The method is characterized in that through utilizing closed-loop control Burst duty cycle under a light load, a degree of control freedom is added, and control precision of an output voltage is higher; through utilizing the closed-loop control Burst duty cycle, the voltage regulation process is smoother, and system robustness is stronger; the Burst frequency can be changed by a digital processor, compared with a traditional method, the Burst frequency can be increased, when output filter parameters are the same, output voltage ripples can be reduced, and the output power quality can be improved; compared with a traditional frequency hysteresis loop and a voltage hysteresis loop, fast detection and controlare not needed, requirements for a sampling rate and the control speed of the digital processor are not high, and easy realization and low cost are achieved.

The invention discloses a hybrid multi-level inverter and a control method thereof, and a high-speed rail permanent magnet traction system. The inverter comprises at least one single-phase bridge armand a direct-current input circuit for providing a direct-current voltage for the at least one single-phase bridge arm. Each single-phase bridge arm comprises a high-voltage low-frequency unit and a low-voltage high-frequency unit which are cascaded; each high-voltage low-frequency unit comprises a two-level upper bridge arm and a two-level lower bridge arm which are coupled in series; the power switching devices in the two-level upper bridge arm and the two-level lower bridge arm are operated in a fundamental frequency mode; each low-voltage high-frequency unit comprises an intermediate connection unit and at least one T-shaped three-level unit which are sequentially cascaded, the intermediate connection unit is composed of two complementary power switching devices, and the last T-shapedthree-level unit of each low-voltage high-frequency unit is connected with an independent output; the intermediate connection unit is in cascade connection with the midpoints of the two-level upper bridge arm and the two-level lower bridge arm; and the power switching devices of the intermediate connection units and the T-shaped three-level units are operated in a high-frequency switching mode.