337 results about "Ac circuit" patented technology

The invention discloses a two-stage multi-mode bidirectional inverter circuit, which comprises a direct-current power supply DC, an alternating-current power supply AC, a DC / DC circuit, a direct-current voltage-dividing capacitor Cb1, a direct-current voltage-dividing capacitor Cb2, a DC / AC circuit and a controller, and is characterized in that a negative electrode of a second port of the DC / DC circuit is connected with a negative electrode of the direct-current voltage-dividing capacitor Cb1 and a negative electrode of a direct-current port of the DC / AC circuit; a middle point of a second port of the DC / DC circuit is connected with a negative electrode of a direct-current voltage-dividing capacitor Cb1 and a positive electrode of a direct-current voltage-dividing capacitor Cb2, and is connected to an alternating-current neutral line N; the AC port of the DC / AC circuit is connected with an AC live wire L1 and an AC live wire L2. The controller stably outputs voltage or current by controlling the DC / DC circuit and the DC / AC circuit, and bidirectional electric energy conversion is achieved. According to the invention, direct-current capacitance and additional circuits do not need to be increased, the size of the device is reduced, the system cost is reduced, the conversion efficiency is improved, and the device can be widely applied to new energy power generation and energy storage and other industrial and civil bidirectional power conversion systems so as to meet the global power supply and consumption requirements.

The invention relates to the technical field of intelligent electrical switches, and particularly discloses an intelligent reclosing air switch arc suppression method and device based on zero-crossing control, and the method comprises the following steps: detecting a voltage zero-crossing point and a current zero-crossing point of an AC loop, and marking an instruction issuing alignment point; the instruction issuing alignment points comprise a switching-on instruction voltage zero-crossing alignment point and a switching-off instruction current alignment point; and calculating a time window, issuing a switch-on and switch-off instruction at a corresponding window point so as to complete the switch-on operation at the voltage zero-crossing prediction point or complete the switch-off operation at the current zero-crossing prediction point, and achieving the purpose of arc suppression by approaching no current under the condition that the switch-on and switch-off completion time point is overlapped with the actual zero-crossing point. According to the intelligent reclosing air switch, the time of switching on and switching off is accurately controlled, generation of electric arcs is effectively reduced, the service life of the intelligent reclosing air switch is prolonged, and the intelligent reclosing air switch has remarkable technical advantages and market application prospects.

The invention discloses an energy storage type SOP black-start method, system and device based on improved VSG network construction control and a medium, and relates to the field of power grid black-start, and the method comprises the steps: an energy storage type converter MMC carries out the active and reactive control based on an improved VSG network construction control strategy; a non-fault side MMC is controlled to firstly close an isolation circuit breaker and slowly charge a direct-current capacitor, and when the voltage reaches a set threshold value, a current-limiting resistor is quitted; the fault side MMC is started by the same step as the non-fault side MMC; after synchronization is completed, AC circuit breakers between the non-fault side MMC and the feeder load and between the fault side MMC and the feeder load are closed respectively; based on the collected power grid power data, MMC output parameters are adjusted to meet the power grid connection condition, the control mode is switched according to the grid connection state, and the black start process is ended. And by arranging the black start resistor for current-limiting charging and sub-module voltage balance control, the phenomena of overcurrent and voltage unbalance in the black start process are avoided.

The invention relates to the technical field of energy storage, and discloses a synchronous test platform for multiple energy storage converters and a control method of the synchronous test platform. The test platform comprises a wire inlet switch, a pre-charging loop, a transformer, an auxiliary power supply switch, an alternating-current circuit breaker, a direct-current circuit breaker and a unit controller, a power grid is connected to the high-voltage side of the transformer through the wire inlet switch and the pre-charging loop in sequence, and one side of the alternating-current circuit breaker is connected with a winding on the low-voltage side of the transformer. The direct current side of the first group of energy storage converters is connected with the direct current side of the second group of energy storage converters through the direct current circuit breaker, and the first group of energy storage converters is connected with the auxiliary power supply. According to the test platform, the pre-charging loop is bypassed after the first group of PCS is pre-charged, then the first group of PCS unlocks the direct current voltage control mode, and the second group of PCS starts in sequence control, so that the synchronous charging and discharging test of 2N PCSs is realized, and the charging and discharging test efficiency of the energy storage converter is greatly improved.

The invention discloses a hybrid multi-level battery energy storage system of a three-port converter. The hybrid multi-level battery energy storage system comprises a direct current port, an alternating current port, a battery port, a choke inductor, a power frequency module, a filtering module, a controller and a plurality of switch modules, the switch modules are divided into two groups, and the two groups of switch modules and a plurality of switch modules in the switch modules form cascade connection and are correspondingly connected with the direct current ports; the choke inductor is arranged between the two groups of switch modules and is correspondingly connected with the filtering module; the power frequency module is connected with the DC port and the filtering module. The power frequency module comprises a commutation circuit formed by two power switch tubes; the controller is electrically connected with the power frequency module and each switch module. When the hybrid energy storage device is connected to photovoltaic and wind power new energy direct current ports, a new energy DC / AC circuit does not need to be additionally arranged, the size of the energy storage device is reduced, and the cost of the hybrid energy storage system is reduced.

The present invention provides a hybrid direct current transmission system and a control method thereof, which belongs to the field of power electronics. The system includes: the rectifier side circuit adopts a heterogeneous series topology structure, the high-voltage valve group adopts LCC to withstand high voltage levels, and the low-voltage valve group adopts MMC to establish and maintain the voltage stability of the grid connection point; the inverter side circuit adopts a distributed connection, wherein the high-voltage valve group adopts LCC, the low-voltage valve group adopts three parallel MMCs, and multiple inverters are distributedly connected to different AC circuits. The rectifier side is composed of LCC and MMC in series, and the inverter side is composed of three parallel MMCs and LCC in series that are distributedly connected to different AC circuits. In this way, the system can provide voltage support for the energy base, has AC and DC fault ride-through function, prevents phase change failure, and improves system stability. In addition, the distributed access method can also achieve flexible power distribution.

The utility model provides an electric energy meter calibrating device comprising a calibrating box body, the calibrating box body comprises a first plate and a second plate which are arranged at intervals along a first direction, and at least one of the first plate and the second plate is provided with at least one first air port; the second air opening is formed in the plate body for connecting the first plate and the second plate; the supporting partition plate is arranged in the verification box body in the first direction, and the space in the verification box body is divided into a first cavity and a second cavity by the supporting partition plate; the plurality of direct-current circuit boards are connected with the supporting partition plate, the direct-current circuit boards are arranged in the first cavity, and at least one direct-current circuit board is provided with a first heating piece; the at least one first fan is arranged on the supporting partition plate, and the first fan and the first heating piece are oppositely arranged; and the plurality of alternating-current circuit boards are connected with the supporting partition plate and are arranged in the second cavity. According to the technical scheme, the direct current circuit board and the alternating current circuit board are arranged in a layered mode, the heat dissipation capacity of the device is remarkably improved, and the temperature of the whole system is kept stable.

The invention discloses an inverter system and a control method and device of the inverter system, and belongs to the field of inverter systems. The inverter system comprises a DC-to-AC circuit, wherein a phase relay is arranged on a phase line connected with the DC-to-AC circuit; the first capacitor and the second capacitor are connected in series between the positive bus and the negative bus of the inverter system; the first switch module comprises a first end and a second end, and the first end is connected to the inverter side ground through a current-limiting resistor in the inverter night repair circuit; the second end is connected with a neutral point between the first capacitor and the second capacitor; the first switch module is set to be switched to a first working mode before grid connection of the inverter system, so that the first end and the second end are conducted, and common-mode rejection is carried out on the inverter system. According to the inverter system, the night repair circuit and the current-limiting resistor thereof can be reused to realize common-mode rejection of the inverter system, so that the common-mode rejection cost is saved, and the safety of common-mode rejection of the inverter system is improved.

The utility model belongs to the technical field of new energy vehicle charging, and discloses an alternating current and direct current integrated charging socket which comprises a square plate, an alternating current socket assembly and a direct current socket assembly are arranged on the square plate, the alternating current socket assembly comprises an AC insulator, an AC tail cover is arranged on the rear side of the AC insulator, and an AC circuit board is arranged in the AC tail cover. The AC circuit board is provided with five AC power contacts, two pin contacts and four chip resistors, the DC socket assembly comprises a DC insulator, the rear side of the DC insulator is provided with a pressing plate, the DC insulator is internally provided with a DC circuit board, the DC circuit board is provided with two DC power contacts and six pin contacts, the DC power contacts are provided with temperature sensors, and the temperature sensors are provided with temperature sensors. And the six pin contacts and the two temperature sensors on the DC circuit board are communicated to the ten-core low-voltage plug-in. The signal pin of the charging gun is in direct contact with the circuit board, signals are collected by the circuit board and then are connected with an automobile control system through a signal line, signal transmission can be carried out without redundant parts and wire harnesses, the structure is simple, and assembly is easy.

The present invention provides a method and system for detecting the switching state of the closing resistor of an AC filter group circuit breaker, which belongs to the technical field of high-voltage AC circuit breakers. The method comprises: loading the closing current recording data of the filter group circuit breaker switching process; performing wavelet decomposition on the closing current recording data of the circuit breaker, obtaining the singular points in the closing current recording data of each layer of the circuit breaker as the starting points of each transient process during the closing resistor switching process of the circuit breaker; performing TLS-ESPRIT decomposition on the recording data of each transient process to obtain the amplitude and attenuation factor of the DC mode, and establishing a corresponding relationship between the amplitude, attenuation factor and the actual resistance value of the closing resistor; fitting two amplitude-resistance curves and two attenuation factor-resistance curves according to the corresponding relationship, as well as the curve function and inverse function of each curve; substituting the amplitude and attenuation factor into the inverse function of the corresponding DC component to calculate the resistance value, and further calculating the number of flashover resistors based on the average resistance value, so as to understand whether a flashover fault occurs.

The invention relates to an AC / DC bidirectional energy efficiency analysis method and analysis system applied to a photovoltaic transformer area. The AC / DC bidirectional energy efficiency analysis method comprises the following steps: synchronously acquiring parameter information in an AC circuit and parameter information in a DC circuit; calculating the active power P1 in the AC circuit and the effective power P2 in the DC circuit according to the parameter information; calculating an electric energy input / output value E1 of the alternating current circuit in the period; and calculating an electric energy input / output value E2 of the direct-current circuit in the period. According to the invention, the bidirectional flow condition of alternating current and direct current electric energy is accurately and efficiently metered, and the metering and analysis result provides powerful support for efficient utilization and lean management of electric energy. By calculating the electric energy ratio, the efficiency and the performance of the system can be directly reflected, the economical efficiency and the reliability of the alternating current and direct current hybrid power distribution network planning scheme can be accurately evaluated, a basis is provided for optimizing system design and operation, and then safe operation of the alternating current and direct current hybrid power distribution network is better guaranteed.

To provide an alternating electric path short-circuit determination device and a method for determining a short-circuit in an alternating electric path which allow identification of the short-circuit in the electric path.SOLUTION: The alternating electric path short-circuit determination device includes: a current source circuit for generating a current with a current value according to the amplitude value of a three-phase alternating signal of a test frequency on a phase-by-phase basis and flowing the generated current in each phase of a test target electric path in a voltage-free state before a determination test is started; and a determination unit for detecting a voltage generated in the test target electric path, while the generated current is being flown from the current source circuit to the test target electric path and determining the magnitude of the voltage with respect to a predetermined threshold value.SELECTED DRAWING: Figure 6

This invention relates to the field of energy storage technology and discloses a synchronous testing platform for multiple energy storage converters and its control method. The testing platform of this invention includes: an incoming line switch, a pre-charge circuit, a transformer, an auxiliary power supply switch, an AC circuit breaker, a DC circuit breaker, and a unit controller. The power grid is connected to the high-voltage side of the transformer sequentially through the incoming line switch and the pre-charge circuit. One side of the AC circuit breaker is connected to the windings on the low-voltage side of the transformer, and the other side is connected to the AC side of the energy storage converter. The DC side of the first group of energy storage converters is connected to the DC side of the second group of energy storage converters through DC circuit breakers. The first group of energy storage converters is connected to the auxiliary power supply. In this invention, after the first group of PCS (Power Storage Converters) is pre-charged, the pre-charge circuit is bypassed. Then, the first group of PCS is unlocked and controlled in DC voltage mode, and the second group of PCS is started sequentially, thereby achieving synchronous charging and discharging testing of 2N PCS, greatly improving the charging and discharging testing efficiency of the energy storage converter.

The invention belongs to the technical field of power electronics, and provides a doubly-fed converter with a slow shutdown function, a wind power generation system and a shutdown method. A direct-current side energy storage circuit is arranged between a grid-side alternating-current circuit and a machine-side alternating-current circuit; when the power grid load is lost, controlling the grid side alternating current circuit to enter a grid construction voltage source mode, and controlling the machine side alternating current circuit to enter a grid following current source mode; the inertia and the maximum safety speed of the rotor are used as boundaries, the maximum energy capable of being absorbed by the rotor is given, and while the slip power of the rotor is increased, the whole machine power is distributed to a machine side converter; and the direct current side energy storage circuit is controlled to dynamically distribute the residual capacity and store or consume the energy, so that slow shutdown can be realized after the fan system loses the load, the torque and power impact caused by sudden load loss due to a fault and sudden off-grid of the fan system is reduced, a transmission chain system is protected, and the fan load is reduced.

Disclosed in the present invention is a high-voltage high-frequency SiC Mosfet novel power transformer, comprising a superordinate computer, a controller, an inverter circuit, and a signal detection circuit. The superordinate computer is connected to the controller; the inverter circuit uses a three-phase T-type inverter topology circuit to convert high-voltage power in a three-phase circuit into three-phase controllable AC power; the inverter circuit comprises a primary rectifier circuit, a primary DC-AC circuit, a three-phase winding transformer, a secondary rectifier circuit, and a secondary DC-AC circuit; a plurality of SiC Mosfets are used in the primary rectifier circuit, the primary DC-AC circuit, the secondary rectifier circuit, and the secondary DC-AC circuit; the signal detection circuit obtains detection data; and a DSP is provided in the controller, the DSP is provided with an algorithm module, the algorithm module performs an operation on the basis of the detection data to generate a specific instruction, and the controller adjusts the inverter circuit on the basis of operating parameters or the specific instruction. In the present invention, a plurality of SiC Mosfets are used, and the structure of the inverter circuit is optimized, thereby improving the working efficiency; and a detection and control feedback mechanism is additionally provided, so that effective regulation within the transformer can be realized, thereby improving the performance.

The invention discloses a voltage circuit breaker AC open circuit control method and device, and relates to the technical field of open circuit control, and the method comprises the following steps: obtaining a target waveform sequence of a target AC circuit, and obtaining a fundamental component and a higher harmonic component through frequency domain decomposition, so as to extract current waveform features; constructing a zero-crossing prediction model based on current waveform characteristics, dynamically correcting the prediction model in combination with higher harmonic components and load asymmetry characteristics, and generating a preliminary breaking moment candidate interval; determining a final on-off moment by combining the instantaneous power direction reversal point and an arc maintenance energy threshold value; and triggering the circuit breaker to act at the final breaking moment, and dynamically adjusting the contact separation speed based on the residual arc energy until the arc energy is attenuated to a safety value. According to the method, the zero-crossing prediction model is constructed by extracting the current waveform characteristics, the contact separation strategy is dynamically corrected, and the problems of arc extension and equipment damage of a traditional circuit breaker under the condition of harmonic distortion or sudden disturbance are solved.

A thermal impedance monitoring process for a power module of a power converter for converting a DC current to an AC current, or converting an AC circuit to a DC current, where a semiconductor dissipates asymmetric losses between two half cycles of an AC frequency f of the AC current, said power module comprising at least a semiconductor die, a semiconductor die is attached to a stack of materials of layers for heat dissipation and / or electrical connection thereof, the process comprising: sampling and measuring a signal related to a junction temperature Tj of the semiconductor die at a frequency higher than twice the AC frequency of the AC current, calculating a duration [Delta] t = tTjmax-tTjmin between a moment tTjmax at which the junction temperature of the semiconductor die is at a maximum value and a moment tTjmin at which the junction temperature is at a minimum value in one cycle of the AC current, and storing the duration [Delta] t in a memory, repeating the step of sampling and measuring said signal and the step of calculating said duration at different times tx = t0 to tm during the operating life of the power module to provide a series of durations [Delta] t0 to [Delta] tm, and comparing the values of said durations [Delta] t0 to [Delta] tm for monitoring the evolution of said duration [Delta] t, and determining the evolution of the degradation of the thermal impedance of the power module.

The present invention provides a single-stage high-frequency isolated DC / AC inverter, comprising a primary-side bridge inverter circuit, a high-frequency transformer, a series resonant cavity and a secondary-side AC circuit which are connected in sequence. The inverter is modulated by a control circuit, and an inverter modulation method is set in the control circuit and comprises the steps of: determining an inner phase shift angle between primary-side bridge arms, an outer phase shift angle between each primary-side bridge arm and a secondary-side bridge arm, and switching frequencies of a primary-side switching transistor and a secondary-side switching transistor on the basis of a fundamental harmonic approximation algorithm, so as to modulate control variables of the inverter, wherein the control variables include a power transmission characteristic and a soft switching characteristic; and calculating precise current values at switching instants of the primary-side switching transistor to compensate the control variables on the basis of the precise current values.

The invention relates to the technical field of vehicle charging sockets, in particular to a charging socket signal switching mode. According to the charging socket signal switching mode, a socket shell is included, an inner cavity of the socket shell is divided into a DC cavity and an AC cavity, a DC circuit board and an AC circuit board are connected with SMD thermistors respectively so as to measure the temperature of DC and AC power terminals, the DC circuit board and the AC circuit board are connected with multi-PIN connectors respectively, and multi-PIN contact pins are integrated in the socket shell. The two ends of the multi-PIN pin extend into the DC cavity and the AC cavity respectively and are connected with the multi-PIN connector of the DC circuit board and the multi-PIN connector of the AC circuit board in an inserted mode, so that a DC power terminal temperature signal is transmitted to the AC circuit board through the multi-PIN connector of the DC circuit board, the multi-PIN pin and the multi-PIN connector of the AC circuit board in sequence and led out through the low-voltage connector of the AC circuit board. Through a signal switching mode of integrating the PINs in the socket shell, the split type design of the AC cavity and the DC cavity can be realized, so that the assembling performance and the sealing reliability of the product are improved.

A high-power-density modular energy storage converter is provided. The converter includes a cabinet divided into a first region, a second region and a third region. The cabinet includes a foundation slab, a front structure, a middle structure and a rear structure. The front structure is arranged in the first region. The middle structure is arranged in the second region. The rear structure is arranged in the third region. The front structure includes a power device and a first air-water heat exchanger. The middle structure includes an electric reactor device, a DC magnetic ring device, an AC magnetic ring device and an AC filter capacitor. The rear structure includes a DC contactor, an AC circuit breaker, an AC pluggable connector, a DC fast fuse device and a DC pluggable connector.

The utility model provides an energy storage converter and an energy storage container. The energy storage converter comprises a housing; the fusing protection assembly is arranged in the shell, and the fusing protection assembly comprises a direct current fuse and an alternating current fuse; the high-voltage control assembly is arranged in the shell, and the high-voltage control assembly comprises an isolating switch and an alternating-current circuit breaker; the conversion control module is arranged in the shell and is configured to convert direct current loaded on the direct current side of the conversion control module and alternating current loaded on the alternating current side of the conversion control module; wherein the isolating switch is connected in series with the direct current fuse, and is electrically connected to the direct current side of the conversion control module; the AC circuit breaker is connected in series with the AC fuse, and is electrically connected to the AC side of the conversion control module.

The invention discloses a power supply electromagnetic compatibility filter which comprises a three-phase alternating current input end, a first-stage differential mode capacitor circuit, a first-stage differential mode inductor circuit, a common mode capacitor circuit, a second-stage differential mode capacitor circuit, a second-stage differential mode inductor circuit and a three-phase alternating current output end which are in communication connection in sequence. Wherein the first-stage differential mode capacitor circuit, the first-stage differential mode inductor circuit, the second-stage differential mode capacitor circuit and the second-stage differential mode inductor circuit form a differential mode signal suppression circuit, and the differential mode signal suppression circuit is used for suppressing differential mode interference signals in a three-phase alternating current circuit; the first-stage differential mode inductance circuit, the common mode capacitance circuit and the second-stage differential mode inductance circuit form a common mode signal suppression circuit, and the common mode signal suppression circuit is used for suppressing common mode interference signals in the three-phase alternating current circuit, so that the problems of substandard electromagnetic compatibility, relatively high cost and huge size in the existing filtering technology are solved.

The utility model relates to a dual high-voltage clamping protection rectification filter circuit for an electric energy meter. The dual high-voltage clamping protection rectification filter circuit comprises three LC filter circuits and clamping high-voltage AC circuits electrically connected with the corresponding LC filter circuits. The clamping high-voltage alternating-current circuit is electrically connected with a rectifier diode; the rectifier diode comprises a forward rectification unit and a reverse rectification unit which are connected in parallel. A filtering common mode unit is electrically connected between the output ends of the three forward rectification units and the output ends of the three reverse rectification units; the filtering common-mode unit comprises an X safety capacitor CN1 and a common-mode inductor LN5 which are electrically connected; and one output end of the filtering common-mode unit is grounded, and the other output end of the filtering common-mode unit is connected with the drain electrode of the MOS tube device QN1 and the RC filtering current-limiting circuit in a branching manner. The device is reasonable in design, compact in structure and convenient to use.

The present invention discloses a multi-height programmable wireless power transmission composite suspension system, comprising: a transmitting end, the transmitting end comprising an excitation source and a transmitting coil connected in series in sequence; a suspension body, the suspension body comprising a receiving coil and an AC phase angle control unit connected in series in sequence; and a system controller connected to the excitation source and the AC control unit respectively, the system controller is used to control the excitation source to adjust the first AC current of the transmitting coil, and to control the AC phase angle control unit to adjust the second AC circuit of the receiving coil. The magnetic suspension is realized by using the force generated by the magnetic field of the transmitting coil and the receiving coil, and wireless power transmission and magnetic suspension height control are realized at the same time.

This application provides a motor drive system, a power system, and an electric vehicle, and relates to the field of power electronic technologies. The drive system is configured to drive a motor that uses a power battery pack as a power supply. The power battery pack includes at least two battery modules that are independent of each other, the drive system includes at least two direct current-alternating current DC-AC circuits, and the battery modules one-to-one correspond to the DC-AC circuits. Each battery module is correspondingly connected to an input end of one DC-AC circuit, and an output end of each DC-AC circuit is connected to a corresponding winding of the motor. The DC-AC circuit is configured to convert a direct current provided by the corresponding battery module into an alternating current to drive the corresponding winding of the motor.

An electric propulsion system for an aircraft, comprising: - an electrical power source (1) including a synchronous generator (11) driven by a heat engine (12), - a first synchronous electric motor (3) connected to an output of the synchronous generator by an alternating current electrical circuit (2), - a rotating propulsion unit (7), characterized in that it comprises: - a direct current electrical circuit (4) comprising, from an input connected to the alternating current electrical circuit: a first alternating / direct current converter (41), a direct current electrical link (42) and a second direct / alternating converter (43), - a second electric motor (5) connected to an output of the direct / alternating converter, - a differential gear train (6) including a first input shaft (61) connected to the first synchronous electric motor,a second input shaft (62) connected to the second electric motor and an output shaft (63) connected to the rotating propulsion unit. Figure for the abbreviation: Figure 1,

The utility model provides an electric power system relay protection tripping matrix rapid detection device comprising a box body, and a control circuit is integrated in the box body; the control circuit comprises a first alternating current air switch, the other end of the first alternating current air switch is connected with one end of a second alternating current air switch, and the other end of the second alternating current air switch is connected with a relay control loop; the relay control loop comprises a knob switch and a static intermediate relay; the knob switch is connected in series with a coil contact in the static intermediate relay; a signal indication loop is connected between the first alternating current air switch and the second alternating current air switch; the signal indication loop comprises a plurality of signal lamps which are connected in series with a normally open contact in the static intermediate relay; two sides of each group of normally open contacts in the static intermediate relay are connected in parallel with a group of plug protection loops. The device can directly judge whether the tripping contact is switched on or not by observing the state of the signal lamp, so that the state of the tripping outlet contact is judged, the test time is greatly saved, and the labor intensity of verification personnel is reduced.

A DC:DC converter includes: a DC:AC converter circuit having DC and AC sides; an AC:DC converter circuit having DC and sides; an AC link connecting the AC side of the DC:AC circuit and the AC side of the AC:DC converter circuit, the AC link including a transformer having a first winding connected to the AC side of the DC:AC converter circuit and a second winding connected to the AC side of the AC:DC converter; a capacitor; and a switch arrangement having a first state and a second state, wherein: in the first state, the capacitor is connected in series between the AC side of the DC:AC converter circuit and the first winding of the transformer; and in the second state, there is a current path between the AC side of the DC:AC converter circuit and the first winding of the transformer that does not include the capacitor.

The present invention provides a low-cost power electronic AC arc-free circuit breaker system, including: three identical and independent current branches, which are connected in series with the three-phase power line to conduct the three-phase load current; an auxiliary branch shared by the three phases, which is connected in parallel with the three current branches in a time-sharing manner through two mechanical switching switches, and is used to assist in conducting the current during the opening, closing and reclosing processes; including a detection module, a control module and a drive module, which are respectively used to detect the three-phase voltage and current information, control the action timing of the three identical and independent current branches and the auxiliary branch shared by the three phases, and drive the auxiliary branch power semiconductor components and the mechanical switching switches to be turned on and off. The present invention also provides a control method for a low-cost power electronic AC arc-free circuit breaker system. The present invention avoids configuring an auxiliary branch for each of the three phases by sharing an auxiliary branch for the three phases, thereby greatly reducing the cost of the power electronic solid-state AC circuit breaker.