98results about How to "Increase the equivalent switching frequency" patented technology

The invention discloses a control method of an H-bridge cascaded active power filter. The control method is designed aiming at solving the problem of low accuracy because of asymmetrical voltage in the existing method. The control method comprises the steps that: nonlinear load current is detected to obtain an expected compensating current value; the reference current value of the active power filter is obtained; the active power filter outputs current to track reference current; and the trigger signal of a cascaded H-bridge power device is obtained through carrier phase-shift pulse width modulation to drive a main circuit power device. The method for detecting the nonlinear load current is an improved synchronous reference coordinate system detection method based on fundamental-wave positive sequence voltage phase locking. The invention additionally discloses the three-phase star-connected H-bridge cascaded active power filter, wherein the capacitance and the voltage of a filter unit are controlled through a voltage controller, and the on and off of a power switch is controlled through a pulse width modulation strategy to adjust an equivalent resistance value. Under the situations that power voltage is asymmetrical and is distorted, the compensating current required by a load can be accurately detected.

The invention discloses a high-power bidirectional multi-way direct-current simulation power supply. The high-power bidirectional multi-way direct-current simulation power supply is characterized by consisting of at least two mutually insulated simulation direct-current power supply units, wherein each simulation direct-current power supply unit comprises an AC / DC converter and a DC / DC converter which are connected in series; an input end of each AC / DC converter is connected with a secondary side winding of an input transformer; an input end of each DC / DC converter is connected with a capacitor in parallel, and a positive electrode of an output end of each DC / DC converter is connected with a diode in series; two ends of each diode are respectively connected with a switch in parallel. The high-power bidirectional multi-way direct-current simulation power supply is universal in function, only needs to adopt different control strategies, can widen the functions without replacing hardware, and solves the problems of high testing cost of existing DC equipment, small capacity, difficulty in expansion, single voltage level and functions and the like.

The invention discloses a traction power supply direct hanging type high voltage comprehensive compensation device, which belongs to the field of electric energy quality control. The traction power supply direct hanging type high voltage comprehensive compensation device comprise 2 K-level cascade arms, 2k energy storage capacitors, and K isolated type both-way DC converts (2). A rectification side voltage converter (3) is connected with an inversion side voltage converter (4) through a high frequency isolating transformer (5). K DC leading-out terminals of the rectification side voltage converter (3) are connected in parallel with power units corresponding to left K-level cascade arms (1-1) through the energy storage capacitors; The K DC leading-out terminals of the inversion side voltage converter (4) are connected in parallel with power units corresponding to right K-level cascade arms (1-2) through the energy storage capacitors; and the level number K is a positive integer from 1 to 100. The traction power supply direct hanging type high voltage comprehensive compensation device can directly access a traction network without an input-output line frequency transformer through an AC reactor, and can realize the comprehensive compensation including negative sequence, idle work, and harmonic wave.

The invention discloses a three-phase power grid disturbance generating device and a control method thereof. The device comprises a three-phase multi-winding transformer, a power module array and an output filter which are connected sequentially, wherein the power module array comprises three groups of power modules corresponding to three-phase output; each power module comprises a three-phase PWM (pulse-width modulation) rectifier, a DC (direct-current) bus link and a single-phase H-bridge inverter which are connected sequentially; input of the three-phase PWM rectifiers is connected with secondary-side three-phase windings corresponding to the three-phase multi-winding transformer; each DC bus link comprises a DC capacitor group; output ends of the single-phase H-bridge inverters are cascaded to form device basic output; each group of power modules comprise at least one low-frequency disturbance generating power module for outputting fundamental waves or outputting the fundamental waves and harmonic waves as well as at least one high-frequency disturbance generating power module for outputting the harmonic waves. The device is controlled with the method. According to the method, the switching frequency of the at least one high-frequency disturbance generating power module is controlled to be not smaller than that of the at least one low-frequency disturbance generating power module. The device is small in size, low in cost and capable of meeting mobile, vehicle-mounted and on-site detection requirements.

The invention provides an AC / DC resonant converter. A power conversion circuit is composed of basic switch units and a resonant tank, a controller adaptively controls the power conversion circuit according to different AC input voltages or different DC output voltages and switches the power conversion circuit into one or more basic switch units which are connected in series and in parallel and stacked to work and work in a high-frequency full-voltage control mode when alternating current input low voltage or direct current output high voltage exists, otherwise, work in a low-frequency partial-voltage control mode when alternating current inputs high voltage or direct current outputs low voltage, the two two-level control modes share the same set of resonant devices to simplify the design of a resonant tank, the controller is internally provided with a multiplier function unit, and the AC input current tracks the frequency and phase of the input voltage in real time so as to realize a power factor correction function. The AC / DC resonant converter directly converts the AC input instantaneous voltage into the DC output voltage, so that a conventional PFC converter and a DC bus capacitor thereof can be saved, the conversion efficiency is improved, and the component cost is reduced.

The invention discloses a modulation method of an inverter and a use thereof. The modulation method of the inverter is applied to inverter topology in a parallel structure, and comprises two parallel three-phase half-bridges, and each three-phase half-bridge comprises a three-phase bridge arm. The method comprises the steps of: modulating by an SVPWM (Space Vector Pulse Width Modulation) method and respectively controlling a switch of each three-phase bridge arm; distributing different duty cycles and sequences of operation; and finally outputting each PWM (Pulse-Width Modulation) control period of two three-phase half-bridges alternately so as to reduce the output current ripple. The method further comprises the steps of: calculating to obtain a target vector and determining a sector according to a rotation angle of the target vector on a coordinate system; further determining the action times T1 and T2 of adjacent natural vectors and zero vector action time T0; and finally determining the duty cycle and sequence of operation of the switch in each phase bridge arm. With the adoption of the system, the modulation method of the inverter and the use thereof have the advantages that a current-sharing reactor can be omitted, and the cost is lowered; and the equivalent switching frequency is increased, the current ripple is reduced, and the size of a rear end LCL filter is reduced.

The invention discloses a digital and analog mixed simulation system suitable for a direct-current power grid. The system comprises a digital side interface and a physical side interface, wherein the digital side interface is used for receiving a first signal from an A / D so that a digital simulation subsystem carries out digital simulation according to the first signal; the digital side interface outputs a second signal to a D / A; the D / A converts the second signal into a corresponding third signal and outputs the third signal to a control system; the control system receives the third signal and a fourth signal from a measuring unit, and carries out operation of tracking control according to the third signal and the fourth signal to generate a fifth signal; and the physical side interface is used for outputting direct-current power quantity according to the fifth signal so that a physical simulation subsystem carries out physical analog simulation according to the direct-current power quantity. According to an embodiment of the invention, the digital and analog mixed simulation system is suitable for digital and analog mixed real-time simulation of a direct-current power system.

The invention discloses a Buck-Boost type bidirectional DC / DC converter with coupled inductors. The Buck-Boost type bidirectional DC / DC converter is characterized in that Buck-Boost type bidirectional DC / DC converter is composed of N paths of bidirectional Buck-Boost circuits through parallel connection, N is greater than or equal to 2 and N is a natural number. Magnetic coupled inductors are adopted to act as the inductors of all the bidirectional Buck-Boost circuits. The coupled inductors are adopted, and the inductors have multiple advantages of high differential mode current sharing inductance, great current sharing effect, small size of the device, low noise and high efficiency under the condition of the same parallel common mode inductance so that equivalent switching frequency can be enhanced, work noise and the size of the inductors can be reduced and conversion efficiency can be enhanced. Both voltage boosting and voltage reduction can be performed in the single direction of the DC / DC converter so that range of application is quite wide.

The invention discloses a current limiting type dynamic voltage restorer and an uninterrupted power supply method thereof; the restorer comprises a current transformer, an A-phase cascade transformer, a B-phase cascade transformer, and a C-phase cascade transformer; the primary side input ends of the A,B and C phase transformers are respectively connected with A phase, B phase and C phase of a power supply, and primary side output ends are respectively connected with a load; A phase, B phase and C phase of an output end of the current transformer are respectively connected in series with secondary sides of the A,B and C phase transformers. The current limiting type dynamic voltage restorer is connected between a power grid and the load in a cascade manner, thus realizing dynamic compensation for the power grid voltage, and limiting power grid short circuit fault current. The uninterrupted power supply method comprises an IGBT bypass work mode, a thyristor follow current work mode and a machinery switch bypass work mode, thus enhancing power grid safety and reliability, realizing load power supply continuity, and ensuring normal operation of the power grid and the load.

The invention discloses a full power wind power grid integration system and a control method, and belongs to the field of a wind power generation technology and a matrix converter. The system and the method are used for realizing the electric energy grid integration of a high-power wind power generator. The system comprises a machine side filter, a 3*6 matrix converter, a network side filter, a three-winding transformer and a control part, wherein the input end of the 3*6 matrix converter is connected with a fan through the machine side filter; the output end of the 3*6 matrix converter is respectively connected with a winding 1 and a winding 2 of the three-winding transformer through the network side filter; a winding 3 of the three-winding transformer is connected with a power grid; the control part comprises a machine side control module, a network side control module and a PWM (pulse width modulation) module, and is used for realizing the maximum power tracking control and the fixed active power and reactive power grid integration control. The current converter provided by the invention uses the 3*6 matrix converter, and has the sine input current and output voltage; a direct current capacitor is not needed; the transmission volume is improved; the practical switching frequency is reduced; the harmonic wave content is reduced; the quality of electric energy of integrated into the power grid is improved.

The invention provides a five-level dual-buck parallel active power filter (APF) and a dual-frequency half-wave control method thereof, belonging to the technical field of power harmonic suppression. The five-level dual-buck parallel APF comprises two same modules, wherein each module comprises a single power tube, a diode series bridge arm, a dual-power tube series bridge arm, an AC side parallel double inductor and a DC side capacitor. In the dual-frequency half-wave control method, current high-frequency half-wave control is adopted for the single power tube and the diode series bridge arm, and voltage low-frequency half-wave control is adopted for the dual-power tube series bridge arm. By using the five-level dual-buck parallel APF and the dual-frequency half-wave control method thereof, the system reliability can be improved, the tracking accuracy of compensating current is higher, and compensating effects are more ideal.

The invention relates to a chained battery energy storage system integrated with an active power filter. The chained battery energy storage system comprises a three-phase main convertor, a three-phase auxiliary convertor, three connection electric reactors and three breakers. In terms of each phase of the battery energy storage system, one ends of alternating current sides of the main convertor are in cascade connection with one ends of alternating current sides of the auxiliary convertor. The other ends of the alternating current sides of the main convertor are connected with one ends of the connection electric reactors respectively. The main convertor is used for achieving active power or reactive power regulation of a power grid dispatching order fundamental wave; the other ends of the alternating current sides of the three-phase auxiliary convertor are connected to form a neutral point of the battery energy storage system. The auxiliary convertor plays a role of active power filtering. The other ends of the connection electric reactors are connected with one ends of the breakers. The other ends of the breakers are connected into a three-phase power grid. According to the chained battery energy storage system integrated with the active power filter, the energy storage technology is combined with the active power filtering technology, the more flexible and diverse electric energy quality adjusting functions are achieved, the system efficiency is high and the cycle life of a battery is long.

The frequency converter (FC) includes rectification unit (RU), DC unit, two pieces of inversion unit with three electrical levels (IUTEL), and two pieces of LC filtering unit with three phases (FUTP). Positive and negative bus bars of RU are connected to positive and negative ends of DC unit respectively. Two pieces of inversion unit are connected to each other in parallel. Positive bus, negative bus, and neutral point of IUTEL are connected to a group of positive bus, a group of negative bus, and a neutral point of DC unit respectively. The output ends of IUTEL are connected to the input ends of two pieces of LC FUTP respectively. The output ends of two pieces of LC FUTP are connected to two groups of three phase winding taps in electromotor respectively. Based on phase shift of carrier wave, the invention makes frequency of equivalent switch of FC rise one time so as to reduce harmonic content of input voltage of electromotor, and raises efficiency of FC effectively.

The invention discloses a none-serial transformer type dynamic voltage restorer compound control method which is a single-phase sine pulse width modulation (SPWM) compound control method based on proportional integration VPI and modified proportional resonance (MPR) double-closed-loop controller parallel running. A single-phase SPWM technology is used in a multi-level inverter of a none-serial transformer type DVR device, and the inverter can obtain high equivalent switch frequency and low switch loss. An inverter control system uses a double-closed-loop control structure of a current inner loop and a voltage outer loop, and the fact that load voltage is maintained at the rated value is guaranteed. The open-loop gain controlled at resonance frequency of the MPR used by the voltage loop is infinite, and complex coordinate transformation, decoupling control and feedforward compensation control in conventional PR control and multiple PI control strategies are avoided.

A high-power power quality comprehensive compensation device comprises a main circuit (1), a main control algorithm implementation circuit (2) and a detection and protection circuit (3). The device transmits an analog signal which is output after passing through an analog signal conditioning circuit to the main control algorithm implementation circuit (2) through the analog signal conditioning circuit in the detection and protection circuit (3). After analog-digital conversion, the control algorithm of the high-power power quality comprehensive compensator is achieved through a DSP chip. A power device IGBT in the main circuit (1) is controlled to emit compensation current in the reverse direction of harmonic current or reactive current in detected load current. Meanwhile, energy compensation can also be performed on unbalanced current of an unbalanced load, and the composite compensation function of the device is achieved.

The present invention is a kind of electrified railway power quality conditioner, comprises single-phase multi-winding transformer, single-phase single-winding transformer, converter (I, II) and electric capacity; One end of the converter I is connected in series, the other end of the converter I is connected in parallel with the capacitor and then connected back to back with the converter II, and the converters II are connected in a chain structure and then connected in series with the single-phase single-winding primary winding. The present invention adopts a single-phase transformer and a chain structure, which can reduce switching loss, improve device operation efficiency and reliability, reduce the number of device links, reduce the complexity of device structure, improve control accuracy, and reduce the pulse output to the control system Synchronization requirements. The invention solves the problems of negative sequence, reactive power and harmonic exceeding standard in the traction station of the electric railway, and has the advantages of small occupied area of ​​the device, small loss, simple control, low cost and high reliability.

The invention discloses an AAC-based multi-module voltage source type inverter. The AAC-based multi-module voltage source type inverter comprises an LC filter and a full-bridge structure which consists of at least four AAC bridge arms, wherein an H bridge fundamental frequency bridge arm leading-out terminal in an AAC upper bridge arm is connected with a power supply positive electrode output end; an H bridge fundamental frequency bridge arm leading-out terminal in an AAC lower bridge arm is connected with a power supply negative electrode output end; each AAC bridge arm comprises an H bridge unit, a bridge arm electric reactor and a bridge arm conduction switch; each H bridge unit comprises a fundamental frequency bridge arm and a high frequency bridge arm which are connected in parallel; the fundamental frequency bridge arm comprises two series-wound fully-controlled switches with anti-parallel diodes; an emitting electrode of one fully-controlled switch is connected to a collector electrode of the other fully-controlled switch; and the H bridge unit is connected with a voltage-stabilizing capacitor in parallel. The inverter provided by the invention is small in size, and can realize conversion from a low-voltage direct current to a high-voltage alternating current; the system frequency is increased by adopting carrier phase-shifting control; each power switching device suffers from relatively low direct current side voltage; and in addition, the AAC-based multi-module voltage source type inverter is easy to enlarge capacity.

The invention discloses a method for controlling an energy storage type converter topology with fault ride-through capability, wherein the converter topology comprises three phase units, each phase unit comprises an upper bridge arm, a lower bridge arm, an upper bridge arm inductor and a lower bridge arm inductor, and each one of the upper bridge arms and the lower bridge arms of the three phase units is composed of a half-bridge sub-module and a quasi full-bridge energy storage sub-module, which are connected in series in a hybrid manner. The method comprises the following steps: determining modulating waves of each half-bridge sub-module and each quasi full-bridge energy storage sub-module in the bridge arm of each phase according to a to-be-output instruction voltage waveform of each phase, performing comparison according to carriers and modulating waves of each sub-module in the bridge arm of each phase to generate a control signal, and separately controlling the turn-on or turn-off of each sub-module in the bridge arm of each phase. The energy storage type converter topology with the fault ride-through capability can increase the inertia of a new energy system, the charging and discharging current of a battery used for energy storage is smooth, and the voltage level is relatively low, therefore the efficient operation and the safety of the battery are ensured. Meanwhile, the energy storage type converter topology has DC side fault ride-through capability and can still store energy in the case of DC side faults.

The invention discloses a carrier phase-shifting controller based on a multi-winding transformer. The carrier phase-shifting controller comprises a carrier phase-shifting modulator (2), wherein carrier Uci amplitudes of N power modules (6) are the same, and phases are respectively 0, Ts / M, Ts*2 / M, ..., Ts*(M-1) / M, wherein Ts is a carrier period, a phase-shifting coefficient M is any integer smaller than and equal to N. Modulating waves Uri of the N power modules (6) use carrier Uci to perform SPWM (sinusoidal pulse width modulation), so that PWM (pulse-width modulation) pulses are generated. In order to solve non-current sharing, caused by carrier phase shifting, of power modules (6), a current-sharing controller (3) is introduced. The carrier phase-shifting controller improves equivalent switching frequency of the system by M times (M being a module number of carrier phase shifting), effectively lowers switching frequency, reduces system switching loss and improves device efficiency. Meanwhile, the simple current-sharing controller (3) is adopted to restrain non-current sharing of the power modules.

The invention relates to a DC transformer for the access of new energy to a DC power grid, and an implementation method for the DC transformer. The DC transformer employs an isolation-type DC / DC converter mode, and is characterized in that the DC transformer comprises a low-voltage side full-bridge converter and a high-voltage side modular multi-level converter; the low-voltage side single-phase full-bridge converter and the high-voltage side single-phase modular multi-level converter are connected through a high-frequency transformer. The DC transformer provided by the invention can achieve the interconnection of a new energy DC power generation station with the low voltage level and a DC power grid with the high voltage level. The low-voltage side single-phase full-bridge converter is used for connecting the new energy DC power generation station with the low voltage level. The high-voltage side single-phase modular multi-level converter is used for connecting the DC power grid with the high voltage level.

The invention relates to a modular subway regenerative braking super-capacitor energy storage device comprising a direct-current touch net, super-capacitor group modules and DC 750-V bidirectional DC / DC modules. The super-capacitor energy storage device is characterized in that one group of super-capacitor group modules and one group of DC 750-V bidirectional DC / DC modules are connected to form one group of regenerative braking modules. Two groups of regenerative braking modules including a first regenerative braking module and a second regenerative braking module are connected in series to the two ends of the direct-current touch net; the first regenerative braking module is connected in parallel with at least one group of regenerative braking modules; and the second regenerative braking module is connected in parallel with at least one group of regenerative braking modules. Because of the plurality of super-capacitor groups connected with each bidirectional DC / DC module independently, the direct series-parallel-connection number of the single super capacitor body is reduced; and on the basis of series connection of the direct-current-side two groups of modules of the DC 750-V bidirectional DC / DC modules, DC 1500-V application is realized and different current requirements are met by direct-current-side parallel connection of multiple groups of DC 750-V bidirectional DC / DC modules. Moreover, the modular subway regenerative braking super-capacitor energy storage device has advantages of high reliability, complete modular design, high efficiency, small size, and flexible meeting of different power needs.

The invention discloses a single-phase inverter. The positive terminal of a direct current power supply is connected with the first end of a first switching tube; the second end of the first switching tube is connected with the negative terminal of the direct current power supply through a second switching tube, a third switching tube and a fourth switching tube which are sequentially connected in series; the second end of the first switching tube is connected with the negative terminal of the direct current power supply through a fifth switching tube, a sixth switching tube and a seventh switching tube which are sequentially connected in series; a first clamping diode is connected between the common terminal of the third switching tube and the fourth switching tube and the common terminal of the fifth switching tube and the sixth switching tube; a second clamping diode is connected between the common terminal of the sixth switching tube and the seventh switching tube and the common terminal of the second switching tube and the third switching tube; an alternating current load is connected between the common terminal of the second switching tube and the third switching tube and the common terminal of the fifth switching tube and the sixth switching tube; and the second switching tube is reversely connected in parallel with a second diode, and the fifth switching tube is reversely connected with a fifth diode. The single-phase inverter provided by the embodiment of the invention can be used for improving the quality of output electric energy of the inverter.

The invention discloses a single-phase inverter, which comprises seven switching tubes. The positive end of a direct current power supply is connected with the negative end of the direct current power supply through a first switching tube, a second switching tube, a seventh switching tube and a fourth switching tube, which are sequentially connected in series. The positive end of the direct current power supply is connected with the negative end of the direct current power supply through a fifth switching tube, a sixth switching tube, a third switching tube and the fourth switching tube, which are sequentially connected in series. A first clamping diode is connected between the second end of the sixth switching tube and the second end of the first switching tube. A second clamping diode is connected between the second end of the second switching tube and the second end of the fifth switching tube. The second end of the second switching tube and the second end of the sixth switching tube are the alternating current ends of the single-phase inverter. The third switching tube is reversely connected in parallel with a third diode. The seventh switching tube is reversely connected in parallel with a seventh diode. According to the single-phase inverter in the embodiment of the invention, the quality of electric energy output by the inverter can be improved.

The invention discloses a three-phase double-T five-level current transformer and a control method therefor. Each bridge arm of the current transformer is formed by the combination and evolution of two three-level T-shaped current transformer bridge arms and two electrolytic capacitors in series connection. Therefore, the current transformer is small in conduction loss, and is high in efficiency. Compared with a conventional five-level current transformer, the current transformer employs fewer power switching devices, and can generate nine different switching states. Therefore, the current transformer can employ the redundant switching states, and outputs the expected level voltage and controls the balance of the voltage of a flying capacitor at the same time. The current transformer employs a control method based on the multicarrier in-phase laminating SPWM modulation technology, and is enabled to have better quality of output electric energy and higher efficiency. When a fault happens to a power switching tube, the current transformer can carry out fault-tolerant operation through employing the redundant switching states. Therefore, the current transformer is very suitable for an occasion with higher requirements for the reliability and efficiency.

The invention discloses a direct grid connected type photovoltaic power station circuit topological structure and belongs to the power and electronic technical field. The direct grid connected type photovoltaic power station circuit topological structure includes photovoltaic components, DC-AC unit modules and a control system; each DC-AC unit module comprises a first H-bridge converter, a second H-bridge converter, a third H-bridge converter and an isolation transformer, wherein the AC side of the first H-bridge converter is connected with one side of the isolation transformer, the other side of the isolation transformer is connected with the AC side of the second H-bridge converter, the DC side of the second H-bridge converter is connected with the DC side of the third H-bridge converter, and the first H-bridge converter and the second H-bridge converter are adopted as a whole and carry out simultaneous phase shifting control to realize soft switching actions of all switches. According to the direct grid connected type photovoltaic power station circuit topological structure of the invention, modular design is adopted. The direct grid connected type photovoltaic power station circuit topological structure has the advantages of easiness in expansion, cascade connection and high frequency.

The invention discloses a high-voltage and high-speed power generator voltage-dropping rectifying PFC system based on an SWISS rectifier. The high-voltage and high-speed power generator voltage-dropping rectifying PFC system based on the SWISS rectifier comprises a high-voltage and high-speed power generator, an input filter, an SWISS rectifier and two controllers. The invention further disclosesa control method of the system. The SWISS rectifier is introduced to the engine side. Double-closed-loop controlling is performed on the rotating speed of the high-voltage and high-speed engine and the input power factor of the rectifier. Furthermore, double-closed-loop controlling is performed on the DC bus voltage and DC-side current of the rectifier. The rectifier can realize a voltage-reducingPFC function. The high-voltage and high-speed power generator voltage-dropping rectifying PFC system can settle a problem of severe stator current distortion of the high-voltage and high-speed powergenerator; and a PFC circuit is combined with a BUCK circuit, thereby improving system stability and efficiency.

The invention relates to a cascade current converter, which is characterized by comprising at least two current converter bridge arms. Each current converter bridge arm comprises a first bridge arm unit and a second bridge arm unit which are connected in series; the series connection point of the first bridge unit and the second bridge unit in each current converter bridge arm is connected with an alternating current outgoing line; the other two ends of the first bridge arm unit and the second bridge arm unit are respectively connected with the anode and the cathode of a direct current bus; the first bridge arm unit comprises n B-shaped bridges (Mj1) connected in series, and the second bridge arm unit comprises n B-shaped bridges (Mj2) connected in series, wherein ji=1...n, j2=n+1...2n, n is a cascade number and n is not less than 1. The invention is mainly used for high and mid-voltage-grade power grids and loads.

Embodiments of the invention provide a single-phase inverter. The single-phase inverter is characterized in that: a positive terminal of a direct current power supply is connected with a negative terminal of the direct current power supply through a first, a second, a seventh and an eighth switch tubes, wherein the first, the second, the seventh and the eighth switch tubes are connected in series successively; the positive terminal of the direct current power supply is connected with the negative terminal of the direct current power supply through a fifth, a sixth, a third and a fourth switch tubes, wherein the fifth, the sixth, the third and the fourth switch tubes are connected in series successively; a second terminal of the first switch tube forms a short circuit with the second terminal of the fifth switch tube; the second terminal of the third switch tube forms the short circuit with the second terminal of the seventh switch tube; the second terminal of the second switch tube and the second terminal of the sixth switch tube are an alternating-current output terminal of the single-phase inverter; the second switch tube is parallelly connected with a second diode in a reverse direction; the third switch tube is parallelly connected with a third diode in the reverse direction; the sixth switch tube is parallelly connected with a sixth diode in the reverse direction; the seventh switch tube is parallelly connected with a seventh diode in the reverse direction. By using the single-phase inverter in the embodiments of the invention, an output power quality of the inverter can be increased.

The invention relates to the technical field of power electronics, and discloses a switch type power amplification device and a method for simulating current transformation control. The switch type power amplification device comprises a simulation-side current transformation circuit, a direct-current bus circuit and a power-side current transformation circuit which are sequentially connected with one another. The simulation-side current transformation circuit comprises an input filter, parallel filter inductors and three-phase two-level parallel arms which are sequentially connected with one another; the input filter is of an LC structure, capacitors are arranged on a side where the parallel filter inductors are arranged, 3n arms are connected with one another on direct-current sides in parallel to form each three-phase two-level parallel arm, each phase of each three-phase two-level parallel arm is provided with the n corresponding arms, and the n is larger than or equal to 2; filter inductors are serially connected with a middle point of each arm, and LCL type filters can be jointly equivalently formed by the filter inductors and the input filter after the filter inductors are subjected to phase separation and are connected with one another in parallel; switches in the three-phase two-level parallel arms are power electronic full-control type devices. The switch type power amplification device and the method have the advantages that the control bandwidth of the switch type power amplification device can be increased, the dynamic response time can be shortened, the adaptability to measured motor control driving devices with different technical characteristics can be improved, and the switch type power amplification device and the method are high in practicality.

The invention relates to a gradient power amplifier, which comprises a PWM sequence generator and an H-bridge circuit pair. The H-bridge circuit pair comprises a first group of H bridges and a secondgroup of H bridges with the same structure; the first group of H bridges comprises a first half bridge and a second half bridge which have the same structure; one end of each half bridge after parallel connection is used for accessing bus voltage and the other end is grounded; the first half bridge of the first group of H bridges comprises an even number of switching tubes which are sequentially connected in series; the control end of the switching tube is connected with a PWM sequence generator; the structure of the second group of H bridges is the same as that of the first group of H bridges; the circuit midpoint of each half bridge is respectively connected with two ends of a load; and the PWM sequence accessed by the second group of H bridges is obtained by phase shifting according tothe PWM sequence accessed by the first group of H bridges. According to the gradient power amplifier, the multi-frequency multiplication technology of the switching tube frequency can be equivalentlyrealized, the power of the gradient power amplifier and the equivalent switching frequency of the switching tube are improved, the ripple current is reduced, and the use reliability of the gradient power amplifier is improved.