275 results about "Pwm inverter" patented technology

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

An aerosol delivery device is provided that includes a substrate configured to carry an aerosol precursor composition, and a resonant transformer including a transmitter coupling device and a resonant receiver coupling device that is positioned in proximity to the substrate. The aerosol delivery device also includes a pulse width modulation (PWM) inverter configured to drive the resonant transformer. The PWM inverter includes a bridge circuit coupled to the transmitter coupling device, and a PWM controller embodied as an integrated circuit and configured to output a PWM signal to the bridge circuit configured to drive the transmitter coupling device to generate an oscillating magnetic field and induce an alternating voltage in the resonant receiver coupling device when exposed to the oscillating magnetic field. The alternating voltage causes the resonant receiver coupling device to generate heat and thereby vaporize components of the aerosol precursor composition.

A method and apparatus for use with a power conversion configuration including a pulse width modulated (PWM) converter, a PWM inverter and master and slave carrier signal generators wherein the master and slave carrier signal generators receive master and slave PWM frequency signals and generate master and slave carrier signals as a function thereof, PWM signals for controlling the converter and the inverter derived by comparing converter and inverter modulating waveforms to converter and inverter carrier signals, respectively, the method comprising the steps of identifying a phase difference between the master and slave carrier signals, using the phase difference to modify subsequent slave carrier signals to substantially conform the slave carrier signal frequency and phase to the master carrier signal frequency and phase and using the master carrier signal and the modified slave carrier signal to generate control signals for the converter and the inverter.

The invention provides a network voltage disturbance generating device, which comprises a three-phase bridge type PWM (Pulse Width Modulation) rectifier and a three-H-bridge three-phase four-wire-system PWM inverter, wherein the alternating current side of the rectifier is connected with an electric network through an L type filter; the direct current side of the rectifier is connected in series with the direct current side of the three-H-bridge three-phase four-wire-system PWM inverter; an LC filter is connected to the alternating current side of the three-H-bridge three-phase four-wire-system PWM inverter; the output end of the LC filter is connected with an isolation transformer; and the secondary side of the isolation transformer is connected with a load. The invention further provides a control method suitable for the device. Due to the adoption of the device provided by the invention, the simulation of a network voltage amplitude, frequency disturbance and an electric network harmonic phenomenon can be realized, bilateral flow of energy can be realized, and active energy transmitted by tested solar-powered grid-connected equipment is fed back to the electric network; and the control method is easy and convenient to implement, and a target reference value can be accurately tracked; and moreover, quick response and small steady-state errors are realized, so that electric network disturbance can be simulated accurately.

A system and method for detecting ground faults in an AC motor drive is disclosed. A fault detection and protection system for an AC motor drive includes current sensors to measure first and second phase output currents, a voltage sensor to measure a DC link voltage, and a desaturation control circuit to determine a voltage and associated current across PWM inverter switches for a third phase of the output. A controller compares the first and second phase currents, the measured DC link voltage, and the voltage across the PWM inverter switches on the third phase, to a plurality of thresholds. The controller detects a ground fault on one of the first, second, and third phases of the three phase output to the AC motor based on the comparisons of the first and the second phase currents, the DC link voltage, and the voltage across the switches to the thresholds.

The invention provides an electric bicycle magnetic coupling resonance type wireless charger which comprises a main circuit part and a control circuit part. The main circuit part comprises a full bridge rectifier and filter circuit, a half bridge inverter circuit, a transmitting end series resonance circuit, a receiving end series resonance circuit, a high frequency transformer T1 and a high frequency rectifier and filter circuit. The control circuit part comprises a receiving end voltage and current detection circuit, a receiving end charging data transmitting circuit, a transmitting end wireless data receiving circuit, a transmitting end current detection circuit, a phase-locked loop frequency tracking circuit, a PWM inverter control circuit and an inverter drive circuit. According to the invention, wireless charging is used to replace wired charging; electric bicycle magnetic coupling resonance type wireless charging is realized; sparks, which are produced in insertion and extraction processes, of a power supply plug are eliminated, and the troubles of influenced plug service life and poor contact are eliminated; the operation of charging is convenient; electrical energy transmission is carried out through resonance coupling; the electrical energy transmission frequency is reduced; and the influence of electromagnetic radiation on an environment is greatly reduced.

A motor driver has a plurality of output circuits each having an upper side switch and a lower side switch connected in series for supplying a current to a motor. The motor driver includes a current detection resistor connected in series with the plurality of output circuits in common for detecting a current supplied to the plurality of output circuits, a position detection circuit for outputting a position signal corresponding to a position of a rotor of the motor, a current command generation circuit for generating a target current command signal based on the position signal and a predetermined phase angle in which a phase angle of the target current command signal is determined by the predetermined phase angle, and a space vector modulation based logic control circuit for commanding a plurality of output circuits that are set in a plurality of switches states for control of an electric motor.

An apparatus and method for converting DC voltage across positive and negative DC buses to three phase AC voltages on first, second and third AC output lines, the method comprising the steps of providing first and second three phase inverters that include a first subset of inverter switches and a second subset of inverter switches, respectively, linking a first choke in series with the first three phase inverter between the positive and negative DC buses and the AC output lines, linking a second choke in series with the second three phase inverter between the positive and negative DC buses and the AC output lines and synchronously controlling the first and second inverter switch subsets so that switching of first and second inverter switch subsets is substantially synchronized among the three phases.

A three-level inverter dead time compensation control method is used for compensating the decrease of system performance caused by dead time. According to the topological structure of a three-phase three-level PWM (pulse width modulation) inverter, the method first sets corresponding dead time and determines the on-off delays of power elements in the inverter; the method then considers the tube voltage drops of the power transistors of the inverter and the tube voltage drops of clamping diodes of the inverter and calculates the common voltage expression of the output neutral point of the inverter; afterwards, according to the sector with three-phase current value and a reference voltage vector, the method determines the relational coefficient between voltage error caused by the tube voltage drops of the power transistors, the tube voltage drops of the clamping diodes and the on-off delays of the power transistors and current, and thereby the total dead time compensation time of each phase of the three-level PWM inverter is worked out. The method takes the dead time, the on-off delays of the power elements and the tube voltage drops into full consideration, solves the problem of voltage and current distortion caused by the dead time effect in the three-level inverter, and enhances system performance.

The energy feedback type AC/DC electronic load simulator consists of two stages of PWM inverters with common DC bus as key parts. The input PWM inverter stage is connected through input filter inductor to the tested power source to constitute the load characteristic simulating part of electronic load; the output PWM inverter stage is connected through the isolating transformer and output filter inductor to the power network to constitute the energy feedback part of electronic load; and the load characteristic simulating part and the energy feedback part are independently controlled. The load characteristic simulating has single instantaneous current value control mode controlling the input load current amplitude and waveform, and the energy feedback has current and voltage double closed-loop control mode including phase lock loop to control the current waveform in the output network side and the bus voltage in the DC side. The present invention has small loss and high network side power factor.

A system is provided for controlling two alternating current (AC) machines via a five-phase PWM inverter module. The system comprises a first control loop, a second control loop, and a current command adjustment module. The current command adjustment module operates in conjunction with the first control loop and the second control loop to continuously adjust current command signals that control the first AC machine and the second AC machine such that they share the input voltage available to them without compromising the target mechanical output power of either machine. This way, even when the phase voltage available to either one of the machines decreases, that machine outputs its target mechanical output power.

The invention provides an unbalance compensation control method of a cascaded power electronic transformer, comprising a control component and a transformer, wherein the transformer is composed of aninput rectifier stage, an isolation stage and an output inverter stage. The input stage is a three-phase star-connected cascaded H-bridge rectifier, the isolation stage is a plurality of independent dual-active-bridge converters, and the output stage is a single-phase PWM inverter. The control method of the present invention includes an input rectifier stage stratification control unit, a voltageclosed loop control unit of an isolation stage and a constant voltage and current sharing control unit of an output inverter stage. The input rectifier stage stratification control unit, is further divided into an upper control unit and a lower control unit, wherein the upper control unit is composed of a coordinate transformation, a positive sequence decoupling control and a negative sequence current suppression, and the lower control unit is an in-phase voltage sharing control. The control method provided by the invention can simultaneously solve the negative sequence current compensation problem of the PET when the voltage at the network side and the three-phase load are unbalanced, thereby promoting the application of the power electronic transformer in the engineering practice.

A switching type power source device used for magnetic field generation coils for an MRI device in which a switching power sources (9˜11) are constituted by a first and a second multi level PWM inverter (12,13) having a same number of potential levels connected in parallel each other with respect to magnetic field generating coils (6˜8) for the MRI device working as a load as well as a switching control circuit (19) for drive controlling the first and the second multi level PWM inverter (12,13) is constituted to drive control the first and the second multi level PWM inverter (12,13) in a manner to shift the switching phases thereof each other, thereby, ripple components in currents output from the first and the second multi level PWM inverter (12,13) are canceled out each other and a current with a further reduced ripple components as a whole can be supplied to the load (6˜8).

The invention discloses a positive-negative sequence voltage feedforward method of three-phase PWM (pulse width modulation) converter which relates to a positive-negative sequence voltage feedforward method and is capable of lowering the influence of lagging and negative sequence voltage of three-phase PWM control on running of a converter caused by. The method comprises the steps of: carrying out phase-sequence separation on an acquired power grid voltage after carrying out Clarke conversion on the acquired power grid voltage so as to obtain a positive sequence voltage component and a negative sequence voltage component; carrying out phase-sequence separation on an acquired current after carrying out Park conversion on the acquired current so as to obtain a positive sequence current component and a negative sequence current component; calculating a positive sequence current loop set value and a negative sequence current loop set value by adopting a PWM control algorithm; carrying outforward-feeding decoupling control on the positive sequence current component and the negative sequence current component to obtain control set voltage of a PWM converter; calculating and respectively carrying out phase angle compensation on a positive sequence synchronous coordinate system and a negative sequence synchronous coordinate system according to angles needed to be compensated in feedforward of positive sequence power grid voltage and negative sequence power grid voltage; synthesizing the control set voltage of the PWM converter and the compensated phase angles after respectively carrying out Park inverse conversion on the control set voltage of the PWM converter and the compensated phase angles to obtain the final control set voltage of the PWM converter. The positive-negativesequence voltage feedforward method of the three-phase PWM converter is suitable for the control process of the three-phase PWM converter.

It is an object of the invention to provide a control device for a synchronous motor which can detect the position of a magnetic pole from a zero speed without requiring a signal generator.

The invention provides a control device for a synchronous motor which drives the synchronous motor through a voltage-operated PWM inverter and controls a torque and a speed of the motor, including means (6-3) for causing a PWM carrier signal to have an arbitrary phase difference between two phases such as UW, VW or WU in three phases of U, V and W, means (11) for extracting a high frequency voltage and a high frequency current which are thus generated from a detecting voltage or a command voltage and a detecting current, and means (12) for estimating a position of a magnetic flux or a position of a magnetic pole by using the high frequency voltage and the high frequency current which are extracted.

An active filter for reducing the common mode current in a pulse width modulated drive circuit driving a load, said drive circuit comprising an a-c source, a rectifier connected to said a-c source and producing a rectified output voltage connected to a positive d-c bus and a negative d-c bus, a PWM inverter having input terminals coupled to said positive d-c bus and negative d-c bus and having a controlled a-c output, a load driven by said a-c output of said PWM inverter, a ground wire extending from said load, and a current sensor for measuring the common mode current in said drive circuit in said ground wire, said current sensor producing an output current related to said common mode current, said active filter comprising a first and second MOSFET transistor, each having first and second main electrodes and a control electrode, and an amplifier driving a respective one of the transistors; said first electrode of said first and second transistor coupled to a common node, said second electrodes of said first and second transistors being coupled to said positive d-c bus and said negative d-c respectively; each of said amplifiers having an input coupled to said output of said current sensor and each having an output connected to a respective one of said control electrodes; and a d-c isolating capacitor connecting said common node of said first electrode of said first and second transistors to said ground wire.

A DC high voltage power source is constituted by an AC-DC converting means (4, 6) that converts a voltage of a commercial AC power source (3) to a DC voltage and steps up the converted DC voltage, a DC-AC converting means (7) that converts the DC voltage stepped up by the previous means to an AC voltage, two insulating transformer (8, 9) that steps up the AC voltage converted by the previous converting means while insulating each others and a series connection of DC voltages obtained after converting the output voltages from the transformers to DCs and smoothing the same. The DC voltage of the DC high voltage power source is used as the power source to current amplifiers (19, 20, 21) constituted by a multi level PWM inverter circuit (18) of 3 levels and the currents flowing through X axis, Y axis and Z axis gradient magnetic field coil (15, 16, 17) in an MRI apparatus connected to these current amplifiers as loads are controlled by a switching control device (18q) so as to meet with current command values (22c1, 22c2, 22c3) from a sequencer 22 in the MRI apparatus. As a result, plural DC high voltage power sources necessary for the multi level PWM inverter is constituted by a comparatively simple circuit, in addition, while suppressing loss in the power sources, a small sized and highly accurate high voltage and large current power source device and a magnetic resonance imaging apparatus using the same are provided.

The invention relates to a support vector machine inverse system composite controller based on a bearingless synchronous reluctance motor. Two expandable current hysteresis loop PWM (Pulse-Width Modulation) inverters and a bearingless synchronous reluctance motor to be controlled are used as a whole to form a composite object to be controlled; a support vector machine inverse system controller is constructed according to a mathematical model of the object to be controlled and is connected in series before the composite object to be controlled of the bearingless synchronous reluctance motor so as to realize the decoupling control between the electromagnetic torque and the radial levitation force of the motor as well as the radial levitation force in two vertical directions; on the basis, a rotating speed closed loop linear controller and two rotor position closed loop linear controllers are respectively designed for the rotating speed of the motor and the rotor positions to form a linear closed loop controller; an finally the linear closed loop controller, the support vector machine inverse system controller and two expandable current hysteresis loop PWM inverters commonly form the support vector machine inverse system composite controller for dynamically decoupling control on the bearingless synchronous reluctance motor. The control speed, the control precision and the dynamic and static performances of the system can pass parameters for adjusting the linear closed loop controller.

An optimized pseudo-random period pattern can reduce audible noise in a system that includes an inverter circuit configured to provide power to an electric machine. A system can include a PWM optimization module (POM) comprising the PPP. A carrier period for a carrier signal used to provide PWM inverter drive signals can be selected in accordance with the PPP. The PPP can be expressed as an array of 200-400 elements, each element a period belonging to a finite set of 2 or more predetermined periods. A period can be selected by index from the array, and the index incremented to progress through the PPP, which can be repeated upon its completion. The PPP can be optimized to reduce audible noise while mitigating inverter losses. Modeling techniques can determine the number of array elements, the number of possible periods, and the period values that optimize the PPP.

A dead-time compensation method is applied to a PWM inverter, which is provided to drive an induction motor using a constant V/f control. The method first calculates a root-mean-square current of the output instantaneous current of the inverter. Afterward, a lookup table of the root-mean-square current is used to obtain a dead-time compensation base voltage and a dead-time compensation per-unit voltage. Finally, the dead-time compensation base voltage is multiplied by the dead-time compensation per-unit voltage to produce a dead-time compensation voltage of the PWM inverter. Accordingly, the method reduces complexity of converting the current to the voltage to reach a faster real-time response. Furthermore, a more accurate dead-time compensation voltage is obtained without increasing hardware costs and the efficiency of operating the induction motor is improved at low speed and light load condition.