35results about How to "Solve the problem of current sharing" patented technology

The invention discloses a parallel structure and a control method for a photovoltaic power generation grid-connected inverter and belongs to the technical field of renewable energy sources. A topological circuit structure of the photovoltaic power generation grid-connected inverter is divided into a parallel structure of single-phase voltage type pulse-width modulation (PWM) inverters and a parallel structure of three-phase voltage type PWM inverters; and in the control method, an outer ring regulator of a control circuit of the parallel voltage type PWM inverters is independent based on a power grid voltage-oriented vector control technology in a control mode of voltage outer ring and current inner ring so as to form a common unified outer ring regulator; control strategies of various inverters are simplified into single closed loop current control so as to achieve the consistency of energy flow directions of the parallel voltage type PWM inverters and avoid ring current; and the parallel current sharing of the voltage type PWM inverters is realized. Therefore, multiple modules of the voltage type PWM inverters are connected in parallel to realize high-power modularized large-scale application.

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.

The invention relates to a voltage conversion device in the electronic power system in order to simplify the loop structure, save switch devices and solve the issues of bidirectional flow of the power as well as the equal flows in the low voltage stages. The device includes 1-4 phases. Each phase is independent with the identifical structure composed of the high voltage stage, the isolation stage and the low voltage stage. The high voltage stage includes 2-30 identical power conversion modules in serial. The isolation stage includes the part of the modulation / demodulation in high frequncies etc. The low voltage stage includes the power conversion module. Comparing with the foreign scheme, the number of the devices is reduced one-third, and the cost also is reduced.

The invention discloses a large-capacity battery converter and control method thereof. The converter of the invention comprises several branch single stage type DC / AC converter modules parallel to one another. Each battery cluster (Battery Cluster BC) converges energy to an AC bus via each branch single stage type DC / AC converter module to be transformed in voltage in order to connect to an AC grid or to operate independently with load. The invention solves the circular current and uniform current problems brought by serial and parallel connection of the battery cluster, and adopts the technology of module combination and alternate balance to effectively improve the system efficiency under low power and power quality at the AC and DC sides and to realize balanced use of the battery cluster. Each battery branch can conduct intelligent charge and discharge management and the control function and the protection function are configured independently to ensure the largest availability of the system. The invention has simple structure, small volume, small energy loss, easy modularization, high reliability, small output harmonic wave, good system expansibility and low requirement to insulating ability of the converter and can operate with reduced capacity when the unit is in failure. The control method of the large-capacity battery converter of the invention is convenient and simple in operation and easy in realization.

The invention discloses a parallel flow air conditioner, comprising a compressor, a compressor muffler, a four-way valve, an indoor unit, a capillary tube assembly, a top tube of an upper fluid collection tube, an upper fluid collection tube, a flat heat exchange tube and a lower fluid collection tube, wherein a first end of the lower fluid collection tube is provided with a gas-liquid separator, the gas-liquid separator is connected with a check valve, the check valve and the first end of the upper fluid collection tube are connected with the same connector of the four-way valve in parallel. The invention also discloses a processing method of the parallel flow air conditioner. In the invention, the parallel flow technology is adopted, cooling and heating can be realized, and the problems that the flow distribution is uneven, the heat exchange efficiency is low, the volume is large and the cost is high can be solved.

The invention provides a dynamic and static current-sharing and multi-chip paralleled power module. The dynamic and static current-sharing and multi-chip paralleled power module comprises ceramic copper-clad plates and multiple power chips; various power chips are arranged on the ceramic copper-clad plates having the same structures in one-to-one correspondence; and the ceramic copper-clad plates are arranged in the circumferential direction in an axially symmetrical manner. According to the dynamic and static current-sharing and multi-chip paralleled power module disclosed by the invention, the symmetry of electrical parameters is realized through circular physical symmetrical structure; due to the optimized layout design, various branch parasitic parameters of the multi-chip paralleled power module are minimized; furthermore, distribution of various branch parasitic parameters is basically same; the non-uniform current distribution problem of the multi-chip paralleled module is solved easily; the multi-chip module design method disclosed by the invention can be used for realizing dynamic current-sharing and static current-sharing of the power module better; the capacity utilization rate of the power module is increased; and furthermore, the dynamic and static current-sharing and multi-chip paralleled power module is adaptive to a fast switching process and a high-frequency power electronic converter by reducing the side effects of a parasitic inductance.

The invention discloses a parallel structure of a voltage source type PWM (Pulse Width Modulation) rectifier and a control method of the rectifier, belonging to the technical field of power electrical application. A topology circuit structure of the voltage source type PWM (Pulse Width Modulation) rectifier includes a parallel structure of a single-phase voltage source type PWM (Pulse Width Modulation) rectifier and a parallel structure of a three-phase voltage source type PWM (Pulse Width Modulation) rectifier. The control method is a vector control technology based on power system voltage orientation, which comprises the following steps of: by use of voltage outer ring and current inner ring control way, separating out an outer ring voltage regulator of a control circuit of the parallelvoltage source type PWM (Pulse Width Modulation) rectifier to form a common uniform voltage regulator, outputting a unique outer ring control voltage, simplifying a control policy into single closed ring current control to solve consistency problem of energy flow direction of the parallel voltage source type PWM(Pulse Width Modulation) rectifier so as to avoid generation of ring current and to provide technical supports for high power, modularization and large-scale application of the multi-module parallel connection of the voltage source type PWM (Pulse Width Modulation)rectifier.

The invention belongs to the field of drive of fracturing pump sets in shale gas extraction, and particularly relates to a multiphase fracturing machine set electric drive control system. The system comprises a ring main unit, a phase-shifting transformer, a frequency converter and a nine-phase motor, wherein high voltage electricity is introduced into the ring main unit from a power grid and converted into at least two nominal-voltage secondary three-phase commutating windings and an auxiliary secondary winding through the phase-shifting transformer, the commutating windings supply power to the frequency converter, and by outputting three sets of three-phase alternating current inversely, the frequency converter drives the nine-phase motor to drive a fracturing plunger pump to work; the auxiliary secondary winding is in charge of supplying power to a control cabinet, an MCC cabinet, a transformer fan and a cooling refrigerator system, and the MCC cabinet is in charge of supplying power to an external lubricating oil circulating pump and a lubricating oil heat-dissipation cooling fan; after state information detection is conducted, the ring main unit, the transformer fan and the nine-phase motor are used for logical judgment of the control cabinet. Compared with conventional diesel / natural gas engines, the multiphase fracturing machine set electric drive control system has theadvantage that the discharging amounts of nitrogen oxides and oxycarbides are almost zero, so that the multiphase fracturing machine set electric drive control system is environmentally friendly; moreover, the energy consumption cost is reduced, and the running cost is low.

The invention discloses a high voltage motor parallel wave chopping and double inversion speed regulation energy-saving controller, which is applied to the stepless speed regulation of a wound rotor type motor loaded on blowers and pumps, and the like in the industries of electric power, cement and metallurgy, and the like. The controller comprises a parallel wave chopper and a double inverter, wherein, the parallel wave chopper comprises flat wave reactors L1 and L2, isolated gate bipolar transistors S1 and S2, fast recovery diodes D1 and D2, and capacitors C1 and C2; the double inverter comprises two independent inverters Q1 and Q2 and a double inversion three winding transformer T, the inverter Q1 comprises six thyristors Q11 to Q16 and a reactor L3, the inverter Q2 comprises six thyristors Q21 to Q26 and a reactor L4, the double inversion three winding transformer T is provided with three sets of windings, wherein, one set of the winding is arranged at the high voltage side and connected into Y-shape by three phases, two sets of the windings are arranged at the low voltage side, wherein, one set of the winding Tq1 is connected into the Y-shape by three phases, and the other set of the winding Tq2 is connected into triangular shape by three phases. The controller can guarantee that the current of the isolated gate bipolar transistors of the parallel loop of each path are basically consistent.

The present invention relates to a parallel structure of three-phase multi-level PWM converters which are suitable for distributed power supplies, and systems for grid-connected power generation with renewable energies, charging and discharging and energy storage therefor and the like. Then present invention includes more than two three-phase multi-level PWM converters and control circuit units thereof, a digital signal processor and a three-phase alternating current power supply circuit; and further includes a common unified voltage regulator, the unified voltage regulator consisting of a voltage sampling circuit, a voltage sensor, a third adder and an external loop voltage PI regulator, the voltage sampling circuit being connected in parallel to a load RL. The advantages of the present invention are as follows: the energy flow direction consistency problem of each three-phase multi-level PWM converter when operating in parallel is solved, the generation of a loop current is avoided, and at the same time the problem of equal current when each three-phase multi-level PWM converter operates in parallel is solved. The present invention is suitable for scenarios in which high power and scaled power electronics conversion is applied.

The invention relates to a parallel connection structure for single-phase multi-level PWM (Pulse-Width Modulation) convertors, which is suitable for a distributed power supply, a renewable energy source generating combined grid, charging / discharging and energy storing systems and the like. The parallel connection structure comprises more than two single-phase multi-level PWM convertors and control circuit units thereof, a digital signal processor, a single-phase alternated power circuit and a shared uniform voltage regulator, wherein the shared uniform voltage regulator is composed of a voltage sampling circuit, a voltage sensor, a third summing unit and an outer ring voltage PI (Proportional Integral) regulator. The voltage sampling circuit is in parallel connection with an RL (Resistance Load). The parallel connection structure for single-phase multi-level PWM convertors has the advantages that the problem of the energy flow direction consistency of the single-phase multi-level PWM convertors in a parallel running process is solved, the circulation current is avoided, the equalized flow problem of the single-phase multi-level PWM convertors in the parallel running process is solved, and the parallel connection structure for the single-phase multi-level PWM convertors is suitable for an application situation of a high-power large-scale power electronic convertor.

The invention provides a multi-phase interleaved Boost convertor. An output end of a generator is rectified through a rectifying circuit and is connected with input ends of Boost circuits and auxiliary power supply respectively, wherein the auxiliary power supply supplies working voltage to a sequence circuit and a control circuit; a signal output end of the sequence circuit is connected with a signal input end of the control circuit; the signal output end of the control circuit is connected with signal input ends of the Boost circuits; and the Boost circuits output voltage for use by load. By the scheme of carrying out voltage stabilization and current balancing on a plurality of Boost circuits by the plurality of interleaved Boost circuits and a voltage-stabilizing loop, the problems of high-power output and current balancing are solved; the current balancing effect is relatively good; a special current balancing circuit does not need to be designed; the input voltage range is wide; and relatively high power factor and efficiency can be obtained.

The invention discloses a gas flow equalizing device of a spraying tower. The device is characterized in that the gas flow equalizing device of the spraying tower comprises flow equalizing plates, wherein the flow equalizing plates are vertically and trapezoidally arranged at the bottom of the spraying tower at unequal intervals; the flow equalizing plates are trapezoidally arranged in direction vertical to a gas incoming direction at unequal intervals; meanwhile, the flow equalizing plates are vertically arranged in a Y direction; the flow equalizing plates are arc-shaped plates, straight plates or the combination of the arc-shaped plates and the straight plates for use. The flow equalizing device is capable of effectively solving the flow equalizing problem of the gas in X and Z directions under the condition that a great difference is formed between the gas inlet diameter and the tower body diameter; meanwhile, the problems of dust deposition, water deposition and scale formation of the flow equalizing device can be effectively solved. Meanwhile, the device is simple, durable and low in cost.

The invention relates to a parallel IGBT module copper bus bar installation structure. The copper bars comprises a short-connected copper bar and a switched copper bar, wherein the switched copper bar is fixedly arranged on the short-connected copper bar; at least one IGBT module is arranged on the short-connected copper bar; and a slotted hole is formed on a short-connected copper bar and between the installation positions of the switched copper bar and the IGBT module on the short-connected copper bar. The parallel IGBT module copper bar installation structure can well solve the problem of uniform flow of each IGBT module and is compact and simple.

The invention relates to a high-current and high-power power converter, which comprises at least two parallel three-phase converters, a rectifying circuit and a filtering circuit, wherein an input endof each of the three-phase converters is connected with a power supply circuit, and an output end is connected to the filtering circuit by means of the rectifying circuit; each three-phase convertercomprises a switching network, a capacitor-inductor combination module and a transformer combination module which are sequentially connected in series; each transformer combination module comprises three phases of transformer combinations, each phase of transformer combination comprises at least two transformers, primary windings of the two transformers are connected in series or in parallel, andthe secondary windings are connected in series; and the primary windings and the secondary windings of each phase of transformer combination are respectively connected with one another to form a starconnection or a delta connection. By implementing he high-current and high-power power converter, special current sharing control is not required, the control is simple and reliable, switching tubes do not need to be used in parallel directly, the current sharing problem of parallel connection of the switching tubes is solved, the severe power imbalance caused by the difference of device parameters is solved, and the high-current and high-power requirements are satisfied.

The invention discloses a constant-power wide-range digital programmable power supply and a control method thereof. A two-stage EMI common-mode filtering unit carries out two-stage EMI common-mode filtering on an input alternating current; a first digital signal processing control unit collects a direct voltage output by a full-bridge rectification unit and feedback current information, controls aBoost conversion unit to carry out Boost rectification conversion on the direct current voltage output by the full-bridge rectification unit, and detects the output voltage after Boost rectificationconversion at the same time. The first digital signal processing control unit compares the Boost output voltage with a set rectified output target voltage, and takes a compared difference value as aninput error instruction of an output voltage closed loop, performs voltage closed-loop PID control calculation on the input error instruction to achieve output target voltage control of the Boost conversion unit. Therefore, the quality requirement of the programmable power supply in actual use is met.

The invention discloses a multi-input parallel and multi-output parallel power converter. The power converter comprises a switch network, an inductor-capacitor combination module, a transformer module, a rectifier module and a filter module, the switch network, the inductor-capacitor combination module, the transformer module, the rectifier module and the filter module are connected in order; theswitch network comprises multiple parallel identical switching circuits; the transformer module comprises a plurality of transformer sets, the transformer sets comprises a plurality of same transformers in which the primary windings are connected in series, and the transformer sets are in one-to-one correspondence connection with the switch circuit; the rectifier module comprises a plurality of rectifying circuits, and the output of the rectifying circuits are connected in parallel; the secondary windings are connected in series of the corresponding transformers in the transformer sets, and the secondary windings are connected in series and then are connected with the corresponding rectifying circuits in the rectifier module for rectification.

The present invention includes a crystallizer mounted on the dummy head on the dummy seat, the upper portion of crystallizer is equipped with flow distribution plate which can possess hot top action. It is characterized by that the bottom portion of the described flow distribution plate is equipped with more than two fow-distributing holes correspondent to every crystallizer. The adoption of said invented equipment can produce aluminium alloy flat ingot, can solve the flow equalization problem in the course of casting process, the cast aluminium ingot does not produce crack, so that the same-level hot top casting process can be adopted in the production of aluminium alloy flat ingot.

The invention relates to a voltage conversion device in the electronic power system in order to simplify the loop structure, save switch devices and solve the issues of bidirectional flow of the power as well as the equal flows in the low voltage stages. The device includes 1-4 phases. Each phase is independent with the identifical structure composed of the high voltage stage, the isolation stage and the low voltage stage. The high voltage stage includes 2-30 identical power conversion modules in serial. The isolation stage includes the part of the modulation / demodulation in high frequncies etc. The low voltage stage includes the power conversion module. Comparing with the foreign scheme, the number of the devices is reduced one-third, and the cost also is reduced.

The invention discloses a locomotive rectifier, which comprises a cabinet body, the cabinet body includes three sub-cabinets, each sub-cabinet is provided with two diodes in series and three radiators, and the diodes and radiators are arranged alternately; each sub-cabinet The outer wall of the cabinet is provided with a terminal and a fast fuse, one end of the fast fuse is connected to the terminal, and the other end of the fast fuse is connected between two diodes; the upper part of the cabinet is also provided with two output terminals, The two diodes in each sub-cabinet correspond to and connect to the two output ends respectively. The rectifier cabinet body of the present invention is formed by connecting and fixing three sub-cabinets with the same structure and size. The rectifier cabinet body of the present invention is changed from an integral type to a split type. It is difficult and time-consuming for personnel to assemble, install and maintain, and it also facilitates transportation and reduces production costs in many aspects; the present invention improves work efficiency while realizing electrical functions.

The invention provides a spray tower with a gas flow equalizing device. The spray tower with the gas flow equalizing device comprises a spray tower, a gas inlet is formed in the lower part of the spray tower; a gas outlet is formed in the top of the spray tower; the spray tower further comprises a circular flow guide cylinder and a conical flow guide cylinder located above the circular flow guidecylinder. An annular flow equalizing area is formed between the circular flow guide cylinder and the tower wall of the spray tower, the gas inlet is formed in the tower wall of the spray tower corresponding to the annular flow equalizing area, the conical guide cylinder is located above the circular guide cylinder, the diameter of the upper end of the conical guide cylinder is larger than that ofthe lower end of the conical guide cylinder, and a gap is formed between the lower end of the conical guide cylinder and the circular guide cylinder. According to the spray tower, gas enters the towerbody of the spray tower, and can only enter the spray area from the gap under the flow equalization effect of the circular guide cylinder. The circular guide cylinder and the conical guide cylinder have buffering and flow equalizing effects so that the gas is more uniform in the spray area of the tower body, the influence of incoming flow change on flow equalization is small, and the flow equalization problem of the gas in the horizontal direction is effectively solved.

The invention relates to a secondary inversion parallel main circuit. The circuit comprises a main transformer T1, and the main transformer T1 comprises a first secondary side winding and a second secondary side winding. The first secondary side winding is connected with a first secondary inverter circuit; the second secondary side winding is connected with a second secondary inverter circuit; a center tap of the first secondary winding and a center tap of the second secondary winding penetrate through the magnetic ring L2 in a staggered manner, then are connected with each other and serve asan output negative end of the secondary inversion parallel main circuit; the output end of the first secondary inverter circuit is connected with the output end of the second secondary inverter circuit and serves as the output alternating current end of the secondary inverter parallel main circuit. According to the invention, a current-sharing inductance wiring method that the main transformers T1with the same iron core and two groups of identical secondary sides and the two center taps of the two groups of identical secondary sides penetrate through the magnetic ring in a staggered manner and magnetic circuits are mutually counteracted is adopted, so the current and voltage waveforms of the upper and lower groups of secondary sides are completely consistent.

The invention relates to a UPS current-equalizing control system comprising an upper current-equalizing control device and lower current-equalizing control devices. The upper current-equalizing control device is used for generating a sampling signal for controlling the sampling of various UPS modules and a switching tube driving signal for controlling the current equalization of the UPS modules. The lower current-equalizing control devices are used for sampling the sampling current of the UPS modules on the basis of the sampling signal, and enabling the current in the UPS modules to be equalized on the basis of the switching tube driving signal. The upper current-equalizing control device generates the switching tube driving signal on the basis of the sampling current. The UPS current-equalizing control system, by means of a double-layer current-equalizing control system formed by the upper current-equalizing control device and the lower current-equalizing control devices arranged in the various UPS modules, is capable of monitoring the sampling current of each UPS module in real time so as to solve a current-equalizing problem of multiple UPS modules in full-load and non-full load states, especially in a light-load or over-load state.

The invention relates to a current-limiting high-voltage direct current breaker, and belongs to the technical field of high-voltage and extra-high-voltage direct current power transmission.The current-limiting high-voltage direct current breaker is composed of a certain number of branches and disconnecting switches; each branch is composed of a current-limiting inductor, a capacitor, a switching tube and a diode to have the effects of shunting and reducing loss.The current-limiting high-voltage direct current breaker is connected in a high-voltage direct current line in series, in normal operation, the inductors in all the branches are made to operate in parallel by means of control of a power electronic device, when the line or equipment breaks down, the current-limiting high-voltage direct current breaker does protective actions, the inductors connected in parallel are connected in series by means of control of the power electronic device, the disconnecting switches are turned on after the inductors are connected in series, then thyristors are controlled to conduct disconnection operation, and therefore the direct current equipment and the line are disconnected quickly.

The invention discloses an elastic sub-module and a modular crimping type semiconductor module. The elastic sub-module comprises a conducting strip, an insulating elastic piece and a conducting plate, the conducting strip is a bent conducting strip which is bent to be provided with a plurality of grooves, the conducting strip is clamped at the upper end of the insulating elastic piece through the grooves, and the lower end of the insulating elastic piece is connected with the conducting plate; the modular crimping type semiconductor module comprises a module collector plate, a chip sub-module, a module emitting polar plate and an elastic sub-module; the chip sub-module comprises a chip, a collector conductor and an emitter conductor; and the module collector electrode plate, the collector electrode conductor, the chip, the emitter electrode conductor, the elastic sub-module and the module emitter electrode plate are sequentially connected from top to bottom. The module has the advantages that the thermal resistance can be further reduced and the power density and the current level of the module can be improved through a chip modularization form; and the modularization of the chip subunits can also reduce the material cost and reduce the processing procedures.

The invention discloses a high voltage motor parallel wave chopping and double inversion speed regulation energy-saving controller, which is applied to the stepless speed regulation of a wound rotor type motor loaded on blowers and pumps, and the like in the industries of electric power, cement and metallurgy, and the like. The controller comprises a parallel wave chopper and a double inverter, wherein, the parallel wave chopper comprises flat wave reactors L1 and L2, isolated gate bipolar transistors S1 and S2, fast recovery diodes D1 and D2, and capacitors C1 and C2; the double inverter comprises two independent inverters Q1 and Q2 and a double inversion three winding transformer T, the inverter Q1 comprises six thyristors Q11 to Q16 and a reactor L3, the inverter Q2 comprises six thyristors Q21 to Q26 and a reactor L4, the double inversion three winding transformer T is provided with three sets of windings, wherein, one set of the winding is arranged at the high voltage side and connected into Y-shape by three phases, two sets of the windings are arranged at the low voltage side, wherein, one set of the winding Tq1 is connected into the Y-shape by three phases, and the other setof the winding Tq2 is connected into triangular shape by three phases. The controller can guarantee that the current of the isolated gate bipolar transistors of the parallel loop of each path are basically consistent.

The invention discloses a constant power wide-range digital program-controlled power supply and a control method. A two-stage EMI common-mode filter unit performs two-stage EMI common-mode filter on the input alternating current; The DC voltage and the feedback current information control the Boost conversion unit to perform Boost rectification conversion on the DC voltage output by the full-bridge rectification unit, and simultaneously detect the output voltage after Boost rectification conversion; the first digital signal processing control unit controls the Boost output voltage and setting The rectified output target voltage is compared, and the compared difference is used as the input error command of the output voltage closed-loop; the voltage closed-loop PID control calculation is performed on the input error command, and the output target voltage control of the Boost conversion unit is realized. In order to meet the quality and quality requirements of the program-controlled power supply in actual use.

The invention belongs to the technical field of integrated circuits, and particularly relates to a charge pump parallel current sharing circuit based on duty ratio control. According to the invention, the equivalent impedance of the charge pump is changed mainly by adjusting the duty ratio, and then the current sharing of the output current during the parallel operation of the charge pump is realized, specifically, the parallel current sharing is realized by enabling the charge pump power tube to work according to the output duty ratio through the duty ratio adjusting module connected with the charge pump. The scheme can be popularized to a charge pump framework with any conversion ratio. According to the scheme, the duty ratio is changed, and the frequency is not changed. Therefore, from the perspective of EMI, the energy spectrum is concentrated on the switching frequency and the harmonic frequency, and almost no energy exists in the range below the switching frequency, so that the design of system EMI is facilitated. The invention provides an analog implementation mode and a digital implementation mode.