61 results about "Phase converter" patented technology

The present invention discloses a multi-phase converter circuit, which includes at least one two-phase converter circuit coupled between a first voltage and a second voltage, and employs switching control of at least one capacitor and at least one coupled inductor, with alternated charging phase and discharging phase, to achieve power conversion between the first voltage and the second voltage.

The invention discloses an on-load voltage regulation distribution transformer with series converter chains bearing partial power, which is characterized by comprising a group of three-phase series converter chains and a three-phase industrial frequency transformer, the three-phase series converter chain is used for three-phase voltage regulation and comprises three converter sub-chains and N4 three-phase converter sink chains, and N4 is equal to 0 or 1; the three-phase industrial frequency transformer is used for isolating and reducing voltage and providing an energy transfer port for maintaining energy conservation of the three-phase series converter chain, the three-phase industrial frequency transformer comprises 3N0 + 3N1 + 3N2 + 3N2 + 3N4 primary windings and three secondary windings, and N0 is greater than or equal to 0; the invention solves the problems of short service life of the contact and power supply interruption of the sensitive load, and realizes continuous voltage regulation with lower equipment cost.

The application discloses a control method of a power distribution line ice melting device, which adopts the power distribution line ice melting device to melt ice, and the ice melting device comprises a parallel side converter, a series side converter, an energy storage capacitor, a parallel side transformer and a series side transformer, the energy storage capacitor is connected between the parallel side converter and the series side converter, the parallel side converter is a three-phase converter, absorbs active power of a fundamental frequency from the power distribution network through the parallel side transformer, the series side converter is a single-phase converter, generates non-fundamental wave current, and injects the non-fundamental wave current into a first end of a line to be melted through a neutral point of the series side transformer to generate Joule heat in the line to be melted to melt ice without power-off operation. Compared with the traditional method, the application can effectively reduce the interference on the power grid, reduce the ice melting cost, and improve the stability and reliability of the system.

The application provides a multifunctional static synchronous compensator system, comprising: a plurality of three-phase converter valves, input ends of each three-phase converter valve being connected to a common DC bus; an energy storage valve, being connected in parallel with the three-phase converter valve, and the plurality of three-phase converter valves sharing the energy storage valve through the common DC bus; a switch breaker device, being arranged between the three-phase converter valve and the energy storage valve; and a control unit, being connected with the plurality of three-phase converter valves, the energy storage valve and the switch breaker device respectively. The application also provides a method for operating the multifunctional static synchronous compensator system. The multifunctional static synchronous compensator system provided by the application adopts back-to-back converter valves, shares energy storage elements through a common DC bus, and connects two AC buses to the two sides of the converter valve, so that the system can support the two AC power grids, greatly save the installation capacity of the energy storage elements in the energy storage valve, and provide power interconnection between the two AC power grids and play a role in tidal flow control.

The invention discloses an alternating current and direct current voltage coordination matching control method of a modular commutation type converter. The method comprises the following steps: generating three-phase sine reference signals corresponding to single-phase converters based on electrical data of an MCC alternating current side; on the basis of a delay commutation trigger mechanism, a commutation delay angle is introduced to modulate a three-phase sine reference signal, so that each cascade module chain is controlled to perform voltage synthesis, and a direct-current side output voltage of the modular commutation type converter is obtained; real-time current data of the MCC direct current side are collected, and when it is judged that the direct current side output voltage or the real-time current data meet the voltage reduction triggering preset condition, a commutation delay angle in a delay commutation triggering mechanism is dynamically adjusted according to the direct current side output voltage and the real-time current data; and a target delay angle is obtained to repeat the modulation process of the three-phase sine reference signal until the voltage reduction trigger preset condition is not satisfied any more, so that continuous and stable operation of the AC side voltage during the abnormal drop period of the DC side voltage is ensured.

The utility model belongs to the technical field of motor forward and reverse phase converters, particularly relates to a motor forward and reverse phase converter with a long service life, and aims to solve the problems that working procedures such as plug dismounting are needed when a motor rotates reversely to adjust phase lines for commutation, labor and time are wasted, the service life is shortened or potential safety hazards are generated in the prior art. Comprising a lower end sleeve and an upper top cover, internal wiring pieces are arranged in the lower end sleeve and the upper top cover, and each internal wiring piece comprises a bottom support, a sleeve, a top plate, a binding post and a spring. According to the utility model, when the upper top cover rotates, the internal contact points are connected with different contact points along with the rotation, the state change causes the change of the circuit connection mode so as to realize the interchange of phase lines, and as the phase change is realized through the rotation, the rewiring or the replacement of a socket is not needed, the conversion of the positive and negative rotation of the motor is realized; the purpose of rapidly adjusting forward and reverse rotation of the motor is achieved, the working efficiency is improved, and time is saved.

This application relates to the field of electromagnetic propulsion technology, specifically disclosing a double-sided long stator linear drive system, including multiple subsystems and a main controller. Each subsystem includes an equal number of linear motor stator segments, six-phase switches, position detection devices, a common AC bus for the subsystem, and a subsystem control bus. The linear motor stator segments are connected to the common AC bus of the subsystem through corresponding six-phase switches, and then connected to the system common AC bus formed by the subsystem bus interfaces, which is connected to a six-phase converter composed of three-phase converters distributed in each subsystem. Each position detection device is connected to the system control bus through the subsystem control bus, and then to the main controller. The main controller controls the switching of each linear motor stator segment according to the installation order of the subsystems and the running position of the linear motor mover measured by the position detection devices. The subsystems can be randomly ordered and assembled without affecting the system operation, exhibiting good mobility.

The invention provides a simulation method and device of a three-phase converter, computer equipment and a storage medium. According to the instantaneous value of the modulation wave and the instantaneous value of the carrier wave, the switching time of the semiconductor device in the three-phase converter from the on state to the off state and the switching time of the semiconductor device from the off state to the on state can be calculated. The switching function of each bridge arm in the three-phase current converter can be constructed according to the switching time of the semiconductor device from on to off and the switching time of the semiconductor device from off to on, and then the three-phase current converter is simulated through the switching functions. According to the method, the switch functions are given based on the two switching moments respectively, the problem of simulation errors caused by non-interpolation of the switch under fixed step length simulation can be solved, namely, the simulation errors can be reduced, and the simulation precision is improved.

The invention discloses a broadband oscillation s-domain modal analysis method for a traction power supply system. The method specifically comprises the following steps: acquiring a topological structure and element parameters of an electrified railway traction power supply system; a single-input single-output s-domain (complex frequency domain) impedance model is formed based on a small-disturbance dq impedance model of power electronic interface loads or power supplies such as locomotive and single-phase converter interface new energy; forming a system s domain node admittance matrix Y (s); in a to-be-analyzed frequency band, performing s-domain scanning on the Y (s) to obtain a system oscillation mode; calculating a damping ratio and an oscillation frequency of the oscillation mode, and a participation factor of each node to the oscillation mode; the method is suitable for broadband oscillation stability analysis of any complex topology traction power supply system containing a single-phase voltage source type converter interface power supply (new energy, energy storage and the like) and an external power system power supply. The system does not need to be divided into an active system and a passive system, and compared with a state space model, the dimensionality is low, and the engineering feasibility is good.

This invention discloses a multi-resource collaborative phase-by-phase fault self-healing method across voltage levels, belonging to the field of power grid fault self-healing. The invention includes: constructing a power supply and load information database covering the entire power grid based on the power grid's overall structure; wherein the power grid's overall structure includes faulty networks and fault-free networks across voltage levels, with the three phases of the faulty and fault-free networks connected via phase-by-phase converters; evaluating each outage node in the faulty network based on the power supply and load information database, determining the fault self-healing strategy for the current outage node; establishing an optimization model for the phase-by-phase converter switching matrix; solving the optimization model for the phase-by-phase converter switching matrix, and outputting the optimal switching matrix for the phase-by-phase converter. This invention achieves phase-by-phase power mutual assistance across voltage levels, while reducing energy waste caused by wind and solar curtailment, and improving the economic efficiency of power grid operation.

The invention discloses a compact converter transformer bus bar wiring and arrangement pattern, the wiring pattern comprises six converter transformers, the converter transformers comprise a first converter transformer and a second converter transformer, and the first converter transformer and the second converter transformer respectively comprise A-phase converter transformer equipment, B-phase converter transformer equipment and C-phase converter transformer equipment; according to the wiring type, the same side phases in the first converter transformer and the second converter transformer are adjacently arranged, and the same side phases are connected in parallel, so that the same side phases share a one-phase bus bar and are led to an alternating-current power distribution device. The bus bar arrangement pattern comprises the step of arranging bus bars which are not connected with side phases in parallel at the end part of the bus bar framework. Compared with the prior art, by adjusting Y / Y and Y / delta converter phase sequence arrangement and connecting a same side phase in parallel, one phase of bus bar can be reduced for each valve hall, and by adopting a compact bus bar arrangement scheme that the phase is arranged at the end part of the framework, the effects of reducing the occupied area of the bus bar framework and saving investment are effectively realized by combining two aspects.

A multi-phase converter system (10) comprises a plurality of power conversion circuits (50) each configured with an inductor and a switching circuit including a power semiconductor. The plurality of power conversion circuits (50) constitute a plurality of master power conversion circuits and a plurality of slave power conversion circuits. A plurality of unit power conversion circuits (40) are configured by allocating the plurality of slave power conversion circuits to one master power conversion circuit in the plurality of master power conversion circuits. The multi-phase converter system (10) comprises: a centralized control circuit (20) that generates a master drive pulse signal for driving and controlling the plurality of master power conversion circuits; and a drive extension circuit (30) that is provided to the plurality of unit power conversion circuits (40) and generates a slave drive pulse signal for driving and controlling the slave power conversion circuits on the basis of the master drive pulse signal. The output terminals of the plurality of power conversion circuits (50) are connected to each other to constitute a system output terminal (Pout). In the output impedances of the current paths from switching-current output terminals of the switching circuits to the system output terminal (Pout) in the plurality of power conversion circuits (50), the plurality of power conversion circuits (50) are disposed so as to reduce the variance of the output impedances of the power conversion circuits (50) constituting the unit power conversion circuits (40). The centralized control circuit (20) controls inductor currents of the plurality of master power conversion circuits so as to be uniform, and controls an inductor current of one master power conversion circuit and the corresponding slave power conversion circuits constituting the plurality of unit power conversion circuits (40) so as to be uniform through the disposition of the plurality of power conversion circuits (50) and the drive extension circuit (30), thereby controlling the inductor currents of all the power conversion circuits (50) so as to be uniform.

The present application belongs to the technical field of engineering machinery, and discloses a resonance-free hydraulic vibration hammer, which comprises a damping frame, a resonance-free vibration gear box, a cross beam and a pile clamping device. The cross beam is installed below the damping frame through the resonance-free vibration gear box. The pile clamping device comprises two pile clamping oil cylinders and two clamps, and the two clamps are installed below the cross beam through the two pile clamping oil cylinders. The resonance-free vibration gear box comprises a box body, a gear phase converter, an eccentric gear set, a transition gear, a first driving assembly and a second driving assembly. Through scientific structural design, the gear phase converter is arranged in the vibration gear box. When starting and stopping, the relative positions between the eccentric blocks of the two pairs of gears are adjusted through the gear phase converter, so that the vertical and horizontal exciting forces generated by the eccentric blocks of the gears are offset. The resonance-free hydraulic vibration hammer adjusts the eccentric torque during starting or stopping of the hydraulic vibration hammer, and eliminates the resonance phenomenon of the vibration hammer during starting or stopping.

This invention discloses a control method, control device, and switching power supply. The control method employs a variable frequency SVPWM modulation strategy, comprising the following steps: calculating the SVPWM modulation wave for controlling the on / off state of each phase bridge arm switch when the electrical parameters output by the N-phase converter reach the desired value through a dual closed-loop control of the voltage outer loop and current inner loop; calculating the frequency required for each phase bridge arm switch to achieve ZVS by predicting the magnitude of the current ripple of the second filter inductor in each phase, comparing the frequencies of each phase, and selecting the minimum frequency among the N phases as the frequency of the triangular carrier wave; using the calculated frequency to generate a shared triangular carrier wave; and comparing the SVPWM modulation wave of each phase bridge arm switch with the shared triangular carrier wave to obtain a PWM drive signal for controlling the on / off state of each phase bridge arm switch. This invention enables soft switching of each sector through variable frequency, eliminating the need for clamping each phase.

The invention discloses a three-phase three-wire system converter open-phase control method and a three-phase alternating current control system. A processor executes the following steps: receiving a power supply signal; judging whether the power supply signal is open-phase or not; if so, judging whether the power supply signal is open-phase at the previous moment; if no phase loss exists at the previous moment, switching from the second operation state to the first operation state, and outputting a first driving signal; if not, judging whether the power supply signal is open-phase at the previous moment or not; and if phase loss occurs at the previous moment, switching from the first operation state to the second operation state, and outputting a second driving signal. According to the open-phase judgment, the three-phase converter can be switched to the first operation state or the second operation state in time due to open-phase or no open-phase, the three-phase converter cannot be shut down, and the first operation state and the second operation state can share partial design, so that the switching of the operation states and the complexity of the system are greatly reduced, and therefore, the switching efficiency of the three-phase converter is improved. And the operation stability of the three-phase converter is greatly improved.

A matrix power converter includes an AC input port arranged to receive three phase power. The AC input port is connected to an input filter arranged to filter switching harmonics of the three phases of the received AC power. The input filter is connected to a 3-to-2 phase matrix converter arranged to convert the three phases of the received AC power to a two phases of AC power. The 3-to-2 phase converter is connected to a primary side of a load transformer arranged to receive the two phases of the AC power. A secondary side of the load transformer is connected to an AC-to-DC converter. The matrix power converter is characterized in that the 3-to-2 phase converter includes a nested directional switch including three power switch cell groups, one for each phase of the received AC input power.

The application concerns a multi-phase AC / DC converter comprising: a transformer device with a primary side and a secondary side; a bidirectional primary side circuit connected to the primary side of the transformer device; a bidirectional secondary side circuit connected to the secondary side of the transformer device; and a DC / DC converter circuit comprising at least one input stage, the transformer device, and an output stage; wherein the bidirectional primary side circuit comprises an AC / DC converter circuit and the at least one input stage of the DC / DC converter circuit; the bidirectional secondary side circuit comprises the output stage of the DC / DC converter circuit; and the primary side circuit is multi-rail with a number of rails corresponding to a number of phases of the multi-phase AC / DC converter, and each rail being connected between a phase and neutral or between a first phase and another phase of a multi-phase AC input source.

This invention provides a control method and apparatus for a six-switch single-phase converter. The method includes the following steps: using multiple power combinations calculated in the previous sampling period, predicting multiple power combinations for the current sampling period, wherein each power combination includes an active power and a corresponding reactive power; calculating the multiple converter output currents for the current sampling period; selecting the optimal solution for the power combinations and converter output currents of the current sampling period using a pre-established cost function, wherein the cost function is a linear combination of a power prediction cost function and a current prediction cost function; determining the switching state combination of the converter for the current sampling period using the optimal solution, and controlling the converter. This invention uses power and current predictions to determine the switching state combination, which not only reduces the computational load of the system but also improves the system's stability and accelerates its dynamic response capability.

The utility model provides an isolated single-phase converter, which relates to the field of power supplies, and comprises a first switch bridge arm formed by connecting a first switch tube and a second switch tube in series; the third switch tube and the fourth switch tube are connected in series to form a second switch bridge arm; the fifth switch tube and the sixth switch tube are connected in series to form a third switch bridge arm, and the first switch bridge arm, the second switch bridge arm, the third switch bridge arm and the first capacitor are connected in parallel; the first inductor is connected between the first end of the alternating current source and the common node of the first switch bridge arm, the second inductor is connected between the first end of the alternating current source and the common node of the second switch bridge arm, the first inductor and the second inductor form a coupling differential mode inductor, and the second end of the alternating current source is connected with the common node of the third switch bridge arm; the first end of the transformer module is connected with the common node of the first switch bridge arm and the common node of the second switch bridge arm, and the second end is connected with the direct current chopper circuit; wherein the isolated single-phase converter is controlled through a control loop of a voltage inner loop and a current outer loop.

The application provides a flexible fusion arc-extinguishing device with phase power series voltage division. The topological structure is a structure in which a phase power and a single-phase converter are connected in series through an isolation transformer, wherein the phase power is obtained through switching and voltage boosting of a secondary winding of a grounding transformer and voltage boosting of a voltage transformer, the single-phase converter is connected in series with the phase power through the isolation transformer, and a DC side power supply of the single-phase converter is provided through rectification of the secondary winding of the grounding transformer by a rectifier. The control algorithm of the flexible fusion arc-extinguishing device is that the phase power is controlled as a voltage source, and the single-phase converter is controlled as a current source. The technical scheme makes up for the deficiency of the voltage arc-extinguishing method that the fault current compensation effect is not obvious in low-resistance grounding fault, and has good engineering application value.

The invention discloses a converter single-loop control method, system and equipment based on an all-drive system model, and belongs to the field of power systems, and the method comprises the steps: carrying out the coordinate transformation of the three-phase voltage and current of a converter and the output voltage of the last moment, and obtaining the two-phase voltage and current, the component of the two-phase output voltage on the d axis is determined as a first output voltage; performing estimation value calculation on the two-phase voltage, the two-phase current and the first output voltage based on the observation parameters, and driving an estimation error to converge to a zero value within a preset time through an observer so as to obtain a disturbance estimation value and a state estimation value of the converter; the disturbance estimation value and the state estimation value are calculated based on the control parameters of the controller established by the all-drive system model to obtain the current voltage, and the control signal is determined according to the current voltage to perform single-loop control on the three-phase converter, so that the disturbance suppression capability of the converter can be improved, and the stable operation of the converter is realized.

The invention belongs to the technical field of electrical engineering, and particularly relates to a multi-level reactive compensation circuit, a control method and a control system, and the circuit comprises a three-phase converter part and a power grid connection part. In three phases of bridge arms of the three-phase converter part, each phase of bridge arm consists of an upper bridge arm and a lower bridge arm, and each group of bridge arms in the upper bridge arm and the lower bridge arm consists of N capacitor sub-modules which are connected in series; the capacitor sub-module comprises a capacitor bank and a half-bridge circuit or a full-bridge circuit connected with the capacitor bank in parallel; the power grid connecting part comprises a filter inductor Ls, an isolating switch QS1, a current transformer CT and a lightning arrester MOA; and the lightning arrester MOA is connected in parallel between the substation bus M and the ground. The four-quadrant reactive power interaction with the power grid is realized, the operation reliability and the service life of the reactive power compensation device are greatly improved, and the voltage stability and the safe operation level of the power grid are enhanced.

The utility model relates to the technical field of single-phase-to-three-phase power supply, and discloses a built-in single-phase and three-phase converter, which comprises a shell, insulators are fixedly mounted on two sides of the shell, a base is mounted at the bottom of the shell, stabilizing components are arranged at the bottom of the base close to the periphery, and a U-shaped block is mounted on the other side of the insulator on one side. A conductor B is arranged in an inner cavity of the U-shaped block, an adjusting assembly is arranged on the conductor B, and a plurality of conductors A are fixedly installed on one side of the insulator located on the other side. When the conductor B is adjusted, under the cooperation of the adjusting assembly, after the position of the driving disc is adjusted, the shifting block can be loosened, and the conductor B can be adjusted. Under the elastic action of a reset spring, an insertion rod fixed to a movable block can be inserted into an inner cavity of an adjacent blind hole, the adjusting position of the driving disc can be locked, the position of the driving disc is prevented from being changed, stable alternating current is provided, and the use safety of an electric appliance is improved.

A through-phase power supply system based on cascaded multilevel converters includes a power electronic converter and a transformer. This through-phase power supply system can simultaneously eliminate phase separation at the substation outlet and at the section substation, achieving full-line power supply and avoiding train speed losses. Furthermore, this system can improve the power quality of the power grid. Compared to existing through-phase power supply systems based on three-phase to single-phase converters, this system uses delta, V-shaped, and diamond-shaped cascaded multilevel converters, which allows for a reduction in converter capacity, thereby lowering costs and increasing its application value.

The invention discloses an inter-phase voltage sharing and current control method and device, computer equipment and a storage medium, and relates to the technical field of three-phase power. The method comprises the following steps: acquiring an initial positive sequence current reference quantity and an initial negative sequence current reference quantity; and carrying out amplitude limiting on the initial positive-sequence current reference quantity and the initial negative-sequence current reference quantity to obtain a final positive-sequence current reference quantity and a final negative-sequence current reference quantity. And obtaining an expected value of the zero-sequence voltage. And taking the final positive-sequence current reference quantity and the final negative-sequence current reference quantity as references, performing closed-loop control on the actual output current of the SVG, and obtaining an initial modulation voltage signal. And according to the initial modulation voltage signal, the expected value of the zero sequence voltage and the voltage compensation component of each power module in the three-phase current conversion chain output by the in-phase voltage sharing module, obtaining a final modulation signal of each power module in the three-phase current conversion chain. According to the invention, seamless switching between an inter-phase voltage-sharing mode based on negative-sequence current and an inter-phase voltage-sharing mode based on zero-sequence voltage compensation can be realized.

An aspect of the present disclosure features a control method for a two-phase converter module. The method comprises sampling a total output voltage of the two-phase converter, a first output current and voltage of a first converter, and a second output current and voltage of a second converter, of the two-phase converter. The method also comprises inputting a first error amount related to the total output to a first controller to obtain a first calculation result. The method also comprises inputting a second error amount related to a total current to a first controller to obtain a second calculation result. The method also comprises comparing values of the first calculation result and the second calculation result, and setting the smaller value as a switching period for the first converter and the second converter after transforming the smaller value to a period.

This invention discloses a frequency-domain modal method for determining the stability of vehicle-to-grid oscillations in new energy systems, applicable to converter impedance measurement. Specifically, it involves: acquiring the topology and component parameters of an electrified railway traction power supply system; performing frequency scanning on the single-input single-output frequency-domain impedance obtained through measurement or mathematical modeling in the frequency band to be analyzed, forming the system frequency-domain node admittance matrix at each frequency; performing eigenvalue decomposition to obtain the amplitude-frequency curve of the modal admittance or modal impedance; determining the oscillation frequency based on the extreme values ​​of the curve; determining the system stability based on the real and imaginary parts of the modal admittance or impedance at the oscillation frequency; and calculating the participation factor of each node in the unstable oscillation mode. This invention is applicable to low-frequency oscillation stability analysis of traction power supply systems with arbitrary topologies that do not contain three-phase converters. The SISO frequency-domain impedance of the single-phase voltage source converter interface power supply and locomotive load can be directly measured through impedance scanning without the need for dq-domain conversion.

The application discloses a single-stage isolated three-phase AC / DC conversion circuit, which sequentially comprises a three-phase AC input end, an input filter module, a high-frequency isolation module, a three-phase full-bridge conversion module, a secondary resonant rectification module and a DC output module; the three-phase AC input end filters out the noise of input through the input filter module; the current filtered by the input filter module flows into the high-frequency isolation module; the primary side of a transformer in the high-frequency isolation module is connected with the midpoint of three bridge arms in the three-phase full-bridge conversion module, the secondary side of the transformer is connected with the secondary resonant rectification module, and the secondary resonant rectification module is connected to the DC output module after rectifying the current. The application realizes wide-area adaptation and topology reconstruction of three-phase / single-phase environment, can not only be used as a standard three-phase converter for efficient operation, but also can be downwardly compatible and reconstructed into a single-phase equivalent circuit, and realizes flexible switching of resonant and linear working states.

The invention relates to the technical field of power grid control, and particularly discloses an enhanced grid-connected control method for a single-phase converter with a current limiting function, which comprises the following steps: a controller controls the single-phase converter in a closed-loop manner through a virtual power grid-filter, and sets a reference current to be 0; when the amplitude of the virtual current is lower than a set threshold value, the virtual current is set as the actual output current of the single-phase converter, and the reference current is set as the actual reference current generated by the controller; the single-phase converter works in an isolated island operation mode; the deviation between the output grid-connected point voltage and the power grid voltage is calculated in real time, and if the deviation continuously meets the threshold condition for a period of time, the working mode of the single-phase converter is switched from the island operation mode to the grid-connected mode. According to the invention, seamless switching between a grid-connected mode and an independent operation mode is realized, and starting synchronization and grid-connected synchronization are guaranteed.

This exemplary embodiment provides a pulse modulation method and apparatus for a three-phase converter. The method includes: within one carrier cycle, changing the arrangement of SVPWM and DPWM, and through the ratio of SVPWM and DPWM, ensuring that the output current simultaneously meets the requirements of the switching frequency and the carrier frequency. Specifically, this includes determining the main resonant frequency point of the system; at f r ~1.5f r Selecting a suitable carrier frequency f s The carrier frequency f s Satisfy frequency multiplication n·f s (n = 1, 2, 3...) staggered from the main resonant frequency points; according to the carrier frequency f s and the switching frequency f r The relationship between SVPWM and DPWM is determined, and the final pulse sequence is arranged according to this relationship. This disclosure achieves control by changing the harmonic distribution of the supporting capacitor current without changing the IGBT switching frequency, eliminating the need for a low-inductance busbar and avoiding the resulting increase in system cost; furthermore, the impact on system losses and waveform quality is minimal as the switching frequency remains unchanged.