318 results about "Pwm converter" patented technology

A family of soft-switched, full-bridge pulse-width-modulated (FB PWM) converters provides zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this family achieve ZVS with the minimum duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing two magnetic components whose volt-second products change in the opposite directions with a change in phase shift between the two bridge legs. One magnetic component always operates as a transformer, where the other magnetic component can either be a coupled inductor, or uncoupled (single-winding) inductor. The transformer is used to provide isolated output(s), whereas the inductor is used to store the energy for ZVS.

The invention discloses a storage battery reduction charge-discharge converter circuit, belonging to the technical field of storage battery reduction. The structure is characterized in that an alternating-current power supply, a three-phase-voltage-type PWM (pulse width modulation) converter, a direct-current bus, a dual-direction DC/DC (direct-current/direct-current) converter module and a storage battery module are connected in series. The storage battery reduction charge-discharge converter circuit provided by the invention has the beneficial effects that the three-phase-voltage-type PWM converter has high power coefficient and low harmonic pollution, dual-direction DC/DC converter module improves the conversion efficiency, dynamic property and power density of a storage battery reduction charge-discharge device, and the volume and weight of a reduction charge-discharge device are reduced; and at the same time, the utilization efficiency of energy is improved, thus the safety, reliability and economy of the system are improved effectively.

A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

A soft-switched, full-bridge pulse-width-modulated (FB PWM) converter and its variations provide zero-voltage-switching (ZVS) conditions for the turn-on of the bridge switches over a wide range of input voltage and output load. The FB PWM converters of this invention achieve ZVS with a substantially reduced duty cycle loss and circulating current, which optimizes the conversion efficiency. The ZVS of the primary switches is achieved by employing an auxiliary circuit comprising an inductor and transformer to store energy for ZVS turn-on of the bridge switches.

A power stabilizing device in a system includes as a portion of a power converter section, a second PWM converter provided between a second primary AC bus and a second DC bus in an electric system and configured to perform mutual conversion between DC power and AC power. A power stabilizing control section in the power stabilizing device controls charging and discharging of a secondary battery based on a voltage and a frequency in the second primary AC bus, thereby stabilizing the electric system.

The invention relates to a controller of full-power alternative-direct converter used in wind generation, wherein the alternative-direct converter is formed by network converter and the convert of generator; the used generator is a permanent-magnetic generator; the rotor is in permanent-magnetic structure, without external magnetic activate power supply; two convert loops both uses the PWM converters operating in four quadrants, based on full-control element, which can improve the dynamic response, reduce cost and impact, realize bidirectional transmission of electricity, and realize generating via power factor sine wave current parallel network; and the invention uses improved direct torque technique to control the converter, to confirm the sine wave change of input current at the stator, with quick response, low vibration, torque dynamic control and wide speed adjust range.

This invention discloses a dual-feed AC-DC-AC converter control structure for wind power generation, and the rotor exciting magnetic converter using the fuzzy PI adaptive control strategy of current inner loop. When the generator no-load networking, the current inner loop uses the conventional PI regulator, and after networking, as to three modes, sub-synchronization, synchronization, super-synchronous, it uses fuzzy adaptive PI control. The network-side converter uses SPWM control strategy which fixed switching frequency and combining electric network electromotive front-feed. In the invention, both converting processes use four-quadrant operation PWM converters based on full-controlled devices, so it can not only improve the system dynamic response, reduce wastage and impact, achieve the two-way electric transmission, but also it can achieve wind power generation network side unit power factor sinusoidal current networking power generation operating.

The invention discloses an electric energy regulation device and method for electrified railways. The electric energy regulation device is in bridging connection between two power supply arms of a traction transformer. The electric energy regulation device comprises isolation transformers, single-phase back-to-back PWM converters, an energy conversion circuit, an energy storage element and a control unit. The control unit carries out calculation according to voltages, currents and directions of the power supply arms alpha and beta and completes control over the PWM converters and the energy conversion circuit. Consequently, energy conversion between the power supply arms alpha and beta and the energy conversion between the energy storage element and the power supply arm alpha or the power supply arm beta can be achieved. The electric energy regulation device is capable of fully recycling and utilizing braking feedback electric energy of a locomotive through transfer, storage and release of the electric energy, improves the energy utilization rate of a tractive power supply system, reduces the installation billing capacity of a traction transformer, can deal with the negative sequence, idle work and harmonic waves of a traction substation, avoids traction force losses and speed losses, caused by electric phase separation, of a train and can also have the effects of peak load shaving and voltage stabilization and can be used as an emergency power supply.

The invention belongs to the field of wind generator power conversion device control, and relates to a constant-frequency direct power control method for a PWM converter under the condition of power grid voltage imbalance. The method comprises the following steps of: determining a sampling frequency; acquiring a three-phase power grid voltage, a three-phase power grid current and a direct-current side voltage, and calculating resultant vectors E and I of the power grid voltage and the power grid current in a three-phase static coordinate system respectively; calculating positive and negative sequence components of the power grid voltage and the power grid current; calculating an instantaneous power and an instantaneous power error; calculating a converter reference voltage, and performing inverse transformation on the converter reference voltage; performing amplitude limit on the converter reference voltage to obtain the resultant vector of the converter reference voltage after the amplitude limit; and modulating the resultant vector of the converter reference voltage after a space vector modulation algorithm is adopted for amplitude limit, and outputting the converter voltage. The method can inhibit the active power fluctuation of the system more effectively and greatly reduce the harmonic wave of the alternating-current side current; and the output converter voltage switch frequency is constant, so the output filter parameter design is simpler.

The invention discloses a synchronous rectification circuit which comprises a converter and an intermittent mode controller, wherein the converter comprises a first synchronous rectification switch; and the intermittent mode controller comprises a logical flow module which is used for eliminating a first driving signal of a switch cycle of the first synchronous rectification switch. The synchronous rectification circuit and the control method thereof can be applied to a resonance converter circuit and a PWM converter circuit.

The invention discloses an AC-DC hybrid micro grid bidirectional power converter virtual synchronization motor control method, and relates to the AC-DC hybrid micro grid virtual synchronization motorcontrol field; the bidirectional power converter is a three-phase voltage source type PWM converter formed by IGBT switch tubes; the AC side is connected to a AC bus via a LC filter and a line impedance Z ac; the DC side is connected to a DC bus via a DC capacitor Cdc and an line impedance Zdc; the energy bidirectional transmission can be realized respectively via a frequency control unit, a virtual excitation control unit and a bidirectional power transmission control unit; the AC frequency and DC voltage can be directly controlled so as to keep AC-DC subnet load balancing; throughput characteristics of various types of power supplies and loads of the AC-DC subnet can be fully utilized so as to provide inertia for the AC frequency and DC voltage, thus enabling the bidirectional power converter to present sagging characteristics under a stable state, and building a bidirectional power converter closed loop system small signal model so as to provide a key parameter design method.

A control circuit and method are provided to generate a modulation signal to operate a power stage in a DC/DC PWM converter such that the DC/DC PWM converter is controlled to operate with high switching frequency in light load stead state, once load transient happens, it still operates with high switching frequency for good transient response, and in heavy load stead state, it is controlled to operate with low switching frequency for good efficiency.

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.

The present invention provides a variable speed constant frequency doubly-fed wind power generation system, characterized in that the system includes a stator grid connected device, a motor, a controlling plate, a dual pwm converter, a code disc; the stator of the motor is connected with the power network by the stator grid connected device; the rotor of the motor is connected with the power network by the dual pwm converter; the controlling plate is connected with the power network, the motor, the dual pwm converter and the stator grid connected device; the controlling plate is also connected with the rotor via the code disc. The system eliminates some influence caused by some parameter error of the generating system according to designing a voltage amplitude compensator and a rotor position angle compensator in the controlling plate.

An apparatus utilizing additive interleaved switchmode (PWM) power conversion stages, having minimal or no output filter, to achieve high bandwidth or even ideally instantaneous power conversion. The additive process may involve voltage stacking of isolated PWM converters, which are interleaved in time, or may involve a single input power supply and inductively combining output currents of PWM power converters interleaved in time, with either additive circuit having minimal or no output filtering. This circuit may overcome limitations for the frequency of feedback control loops once thought to be physical limitations, such as, fundamental switching frequency, output filter delay and the Nyquist criteria.

The invention discloses an energy-regeneration type converter power test system and method. The system comprises a power grid, an isolation transformer, a first smoothing reactor, a second smoothing reactor and a tested converter. The tested converter comprises a first PWM converter, a second PWM converter and a direct current bus capacitor, wherein the first PWM converter and the second PWM converter transmit active power under the buffer effect of a direct current bus capacitor. The first PWM converter imitates load characteristics of the system. The second PWM converter achieves system energy regeneration, unit power factor inversion is achieved by controlling the output currents of the second PWM converter and the voltages of the power grid to be identical in frequency and phase, and the active power balance between the input and the output of the tested converter is achieved by controlling the direct current voltages between the first PWM converter and the second PWM converter to be constant. The energy-regeneration type converter power test system and method can effectively ensure test quality, improve test efficiency, improve the equipment utilization rate, save equipment cost, save energy, reduce emission, simplify operation entry barriers and eradicate potential safety hazards.

The invention discloses a novel multifunctional fault current limiting system based on an optical storage technology and a control method thereof. The novel multifunctional fault current limiting system mainly comprises a photovoltaic power generation part, a storage battery energy storage part, a PWM converter and a fault current limiting part. The photovoltaic power generation part, the storage battery energy storage part and the PWM converter share a DC bus, and energy is exchanged among the photovoltaic power generation part, the storage battery energy storage part and the PWM converter. When the voltage quality problems of falling, rising and three-phase imbalance happen to the voltage of a power grid, compensating voltages are provided for the power grid through the PWM converter. Meanwhile, when short circuit faults of different types happen to the power grid, the system intrudes inductance into the system for current limiting by controlling the fault current limiting part. The novel multifunctional current fault current limiting system based on the optical storage technology and the control method thereof can achieve the purposes of stabilizing the load power supply voltage, improving the power supply quality and limiting short circuit currents through solar energy resources.

The invention discloses an operation control method of a DFIG grid side and a rotor side PWM converter. The operation control method is used to aim at engineering demands of grid-connected wind power generation system simulation analysis. A double-fed induction wind power generator grid side PWM converter mathematical model is established, and a grid side converter control method based on d-axis power grid voltage orientation is designed, and current tracking control and inverter direct current busbar voltage equalization control are realized. A rotor side converter mathematical model is established, and a DFIG rotor current control method of stator magnetic flux linkage orientation is designed. A 2MW double-fed asynchronous power generator simulation analysis model in a PLECS software platform is established and a sub-synchronous state, a super-synchronous state, and a transition process from the sub-synchronous state to the super-synchronous state are analyzed in a detailed way, and according to a result, the designed mathematical model and the control method are feasible.

The invention discloses a non-isolation type three-phase three-level V2G charge-discharge topological structure. The non-isolation type three-phase three-level V2G charge-discharge topological structure comprises a main circuit module and a control circuit module, wherein the main circuit module comprises three parts in cascading manner, including a DC/DC part, an H bridge balance circuit and a DC/AC part; a vehicle-mounted power battery is connected to a direct current positive bus and a direct current negative bus through a bidirectional half-bridge converter; the H bridge balance circuit and two voltage-division capacitors C1 and C2 are arranged between the direct current positive bus and the direct current negative bus, and the direct current positive bus and the direct current negative bus are connected with the output end of the bidirectional half-bridge converter in parallel; the direct current buses are connected with a diode clamping type three-level PWM converter; a three-phase alternating current power supply live wire is connected to connecting places of upper and lower bridge arms of each phase of the bridge arms through a three-phase LC filter; the direct current buses are positioned in the H bridge balance circuit; according to the H bridge balance circuit, an IGBT switch tube Tb1 is in anti-parallel connection with a rapid recovery diode, or the switch tube Tb1 with an in-vivo parasitic diode is connected with a one-way conducive free-wheeling diode Db1 in series to form one side bridge arm, and a balance inductor Lb1 is connected in the middle thereof; the other end of the balance inductor is connected to a direct current side middle point; the bridge arms on the two sides are connected with a shared negative electrode and a shared positive electrode; and namely, the upper ends of the bridge arms are both connected to the direct current positive bus while the lower ends of the bridge arms are both connected to the direct current negative bus.

The invention discloses a mechanical coupling type magnetic suspension wind turbine generator yaw system which is applied to a large and medium wind turbine generator. The mechanical coupling type magnetic suspension wind turbine generator yaw system comprises a planet gear, a conical gear, an electromagnetic clutch, vertical suspension windings, horizontal suspension windings and yaw motors. Wind turbine generator yaw mechanical torque and yaw motor torque are coupled through planet gear torque to drive a wind turbine generator cabin to be yawed. The wind turbine generator yaw mechanical torque is taken from electric generator front side wind turbine generator torque through the electromagnetic clutch and the conical gear with the fixed transformation ratio. The yaw motor torque is controlled by a bidirectional PWM converter during cabin suspension, cabin suspension is jointly controlled by the horizontal suspension windings and the vertical suspension windings, the cabin gravity is balanced through the horizontal suspension windings, the vertical suspension windings restrain off-centering, the yaw motors can work in the two modes including the electric mode and the regenerative braking mode through changes of the wind turbine generator yaw torque, and bidirectional energy flowing is completed through the PWM converter. According to the mechanical coupling type magnetic suspension wind turbine generator yaw system, the yaw power energy conversion link is omitted, the yaw power consumption is greatly reduced, and the wind energy use rate is improved.

The invention relates to a flywheel energy storage system and a control method thereof. The flywheel energy storage system comprises two three-phase voltage type PWM converters, an LCL filter and a direct current support capacitor; the two three-phase voltage type PWM converters are connected with each other through the direct current support capacitor connected with a direct current bus in parallel, wherein one three-phase voltage type PWM converter is connected with a power grid side through the output LCL filter while the other three-phase voltage type PWM converter is connected with a permanent magnet synchronous motor for powering the armature winding of the stator of the permanent magnet synchronous motor. The control method is achieved based on the control of a complex vector PI current regulator, and comprises a control strategy on the three-phase voltage type PWM converter at the power grid side, and a control strategy on the three-phase voltage type PWM converter at the motor side; according to the control method, dependence of the system on circuit parameters is eliminated, robustness of the system is increased, the pole-zero of the complex vector PI current regulator can be completely counteracted without being influenced by change of inductance parameters and the like, and thereby control performance is more outstanding.

A system and method for controlling a digital pulse-width modulated power converter achieves a fast large-signal transient response while maintaining a slow response near the steady-state operating point in order to assure stability and to reduce the system's susceptibility to noise. Digital output error samples are processed through a gain scheduling block that applies a non-linear gain function to produce a weak loop response when the system is near its steady-state equilibrium point and a strong loop response when large transients are encountered. The resulting system maintains a fast transient response to large error signals while reducing noise and loop jittering and assuring loop stability.