106 results about "Current source inverter" patented technology

A multi-motor drive in which the resonance existing between one or more output filter capacitors of a current source inverter and an a.c. induction motor is reduced. The inverter features a switching pattern generator which controls the power switches of the inverter based on a reference current. A control loop, connected to the switching pattern generator, measures the load current or voltage and generates a nominal reference current based on an error therein; determines a damping current based on the voltage at the terminal; and determines the reference current supplied to the switching pattern generator by subtracting the damping current from the nominal reference current. The invention essentially simulates the use of a physical damping resistor connected in parallel with each output filter capacitor, but without the corresponding energy loss. This form of active damping control is also applied to a resonance mode existing between the input filter capacitors of a PWM-based rectifier and the system inductance of a power source.

Power conversion apparatus and methods are presented for providing electrical power to a grid or other load in which a synchronous machine is driven by a wind turbine or other prime mover to provide generator power to a switching type current source converter (CSC), with a current source rectifier (CSR) of the CSC being switched to provide d-axis control of the synchronous machine current based on grid power factor feedback, and with a current source inverter (CSI) of the CSC being switched to provide leading firing angle control and selective employment of dumping resists to dissipate excess generator energy in a fault mode when a grid voltage drops below a predetermined level.

The drive for an a.c. induction motor features a rectifier for converting alternating current into direct current and a current source inverter for converting direct current into alternating current supplied to a motor. A d.c. link choke interconnects the rectifier and the inverter. The inverter includes a first control loop which provides a desired or command d.c. link choke current to a second control loop responsible for the rectifier. For the purposes of the second control loop the actual d.c. link choke current and an input voltage of the inverter are detected. The difference or error between the desired and actual d.c. choke currents are minimized by a compensator. The output of the compensator is added to the detected inverter input voltage, and the sum is fed to a switching pattern generator which controls the switches in the rectifier. In this manner the feedback of the inverter input voltage is decoupled from the compensator responsible for the d.c. link choke current. This makes the parameters of the second control loop substantially independent of the load, thereby enhancing the ease with which the control loop may be tuned and hence the stability of the drive.

Power from the dc outputs of wind-generated power collection nodes is converted to ac power of suitable quality for injection into an electric power grid. Conversion is accomplished by current regulation of the dc outputs of the wind-generated power collection nodes to the input of each one of multiple inverters in a system, with each inverter outputting multiple phase currents that are out of phase with the multiple phase currents outputted from all other inverters in the system. The multiple phase currents from all of the inverters in a system are connected to the secondary windings of a phase transformation network that produces a three phase current output having a step-shaped waveform for injection into the electric power grid. Alternatively the dc input to each one of the multiple inverters may be a combination of the dc outputs of wind-generated power collection nodes and the dc outputs of solar photovoltaic power collection nodes.

A renewable energy, utility size electric power system is provided with a high voltage, renewable energy harvesting network connected by a direct current link to a centralized grid synchronized multiphase regulated current source inverter system. The harvesting network includes distributed renewable energy power optimizers and transmitters that control delivery of renewable energy to the grid synchronized multiphase regulated current source inverter system. A visual immersion monitoring and control system can be provided for a three-dimensional, visually-oriented, virtual reality display, command and control environment.

Current source converter drives and common mode voltage reduction techniques are presented in which a space vector modulation zero vector for current source inverter (or rectifier) control is selected according to the switching state of the current source rectifier (or inverter) and according to the AC input power and the AC output power to control the output common mode voltage.

In controlling switching elements of a current source inverter, a switching loss in the switching element is prevented according to a normal switching operation for a commutation operation, without requiring any particular control.

In the commutation operation of the current source inverter, a timing for driving the switching elements is controlled in such a manner that an overlap period is generated, during when both a switching element at the commutation source and a switching element at the commutation target are set to be the ON state, a resonant circuit is controlled based on the control of the switching elements having this overlap period, and resonant current of the resonant circuit reduces the switching loss upon commutation operation of the switching elements. By controlling the generation of the resonant current of the resonant circuit by using the control of the switching elements having the overlap period, the resonant current generated by this control renders current and voltage of the switching element at the commutation source to zero when commutation is performed, thereby reducing the switching loss in the commutation operation.

Electric power from typically unstable multiple dc sources is converted to ac electric power of suitable quality for injection into an electric power grid. Conversion is accomplished by current regulation of the output from the dc sources to the input of each one of multiple inverters in a system, with each inverter outputting multiple phase currents that are out of phase with the multiple phase currents outputted from all other inverters in the system. The multiple phase currents from all of the inverters in a system are connected to the secondary windings of a phase transformation network that produces a three phase current output having a step-shaped waveform for injection into the electric power grid.

The present invention provides a system, apparatus and method for driving a permanent magnet (PM) machine supplied by a Current Source Inverter (CSI). A DC-DC voltage to current converter (chopper) with an inductor value inversely related to the operating frequency of the DC chopper for a given DC Link current ripple, acts as a current source for the CSI. The DC source for the DC-DC voltage to current converter can be from a DC power source or supply, or an AC power source or supply electrically connected to a rectifier/Pulse Width Modulated (PWM) rectifier.

A renewable energy, utility-size electric power system is provided with a high voltage, renewable energy harvesting network connected by a direct current link to a centralized grid synchronized multiphase regulated current source inverter system. The harvesting network includes distributed renewable energy power optimizers and transmitters that control delivery of renewable energy to the grid synchronized multiphase regulated current source inverter system by step-up voltage boost of the DC voltage from the renewable energy sources in combination with a DC-to-DC conversion where the stepped-up voltage of the renewable sources is utilized as a positive high voltage DC output across the input of an inverter used in a DC-to-DC converter to establish an equal magnitude negative high voltage DC output across a rectified output of the inverter. A visual immersion monitoring and control system can be provided for a three-dimensional, visually-oriented, virtual reality display, and command and control environment.

The present invention is directed to an auxiliary circuit for reducing low order current harmonics in a three-phase drive system driving a single-phase load, the three-phase drive system including a three-phase source voltage connected to a rectifier system connected to a DC link choke inductor connected to a three-phase current source inverter system.

The invention discloses a multiple-resonance inhibition method for connecting multiple inverters into a weak grid in parallel. The method comprises the steps that capacitor voltage feedback quantities are introduced into current control ring forward channels of all the inverters and closed-loop links where the feedback quantities are located are set to be trap filter characteristics through control of active trap filters of capacitor voltage feedback of LCL filter circuits on the basis of the principle that in a parallel system of the multiple same-type current source inverters containing LCL filters, resonance peaks occur at the resonant frequencies of a transfer function of the parallel system, and therefore on the basis of active correction of the trap filters, the negative resonance peaks are achieved at the multiple resonant frequencies, and signals at the resonance points are shielded from the interiors of the inverters.

A renewable energy, utility-size electric power system is provided with a high voltage, renewable energy harvesting network connected by a direct current link to a centralized grid synchronized multiphase regulated current source inverter system. The harvesting network includes distributed renewable energy power optimizers and transmitters that control delivery of renewable energy to the grid synchronized multiphase regulated current source inverter system. A visual immersion monitoring and control system can be provided for a three dimensional, visually oriented, virtual reality display, and command and control environment.

The provided current source inverter includes a buck converter having an input capacitor and an output inductor, receiving a DC input voltage, and generating an output inductor current, a DC/AC converter having an output capacitor, receiving the output inductor current and generating an AC output voltage, a load coupled to the DC/AC converter, and an energy clamp circuit coupled to the buck and the DC/AC converters. The energy clamp circuit includes a first diode and a second diode, provides a discharging route while the load is disconnected with the output capacitor such that the electrical power stored at the output inductor could be discharged to the output capacitor and the input capacitor and avoids an inrush current.

The dual-way tri-level soft switch DC/DC for superconductance energy-storage comprises a voltage unit composed by two tri-level semi-bridges with midpoint clamping diode, a transformer unit, and a current unit with structure decided by the last unit, total-bridge/semi-bridge current source inverter for common transformer/transformer with middle tap. Wherein, paralleling capacitors on every switch tubes of the semi-bridge, or paralleling not; connecting midpoints of semi-bridge and clamping diode to midpoint of connecting line of two voltage-dividing capacitors. This invention can overcome the unbalance problem of midpoint voltage.

The invention relates to a low-voltage ride through circuit of a double-feed type wind power generator, which utilizes a superconducting magnet as an energy storing core. A superconducting magnet is charged and discharged, active power provided by a double-feed type wind power generator is adjusted in a normal state, and the active power provided by the wind power generator is smoothed, thereby improving the electric energy quality of wind power generation, reducing influence to a power grid and compensating the fluctuation of the active power output by a wind power generating system. When the voltage of the power grid is abnormal, a compensating voltage is connected in series between the power grid and a stator of the double-feed type wind power generator through a transformer and a current source inverter circuit, therefore, the voltage of the stator end of the double-feed type wind power generator maintains a normal state, the wind power generating system can be still run online when the wind power generating system generates voltage temporary reduction, and thereby the low-voltage ride through requirement of a power system on the wind power generator is met.

The invention provides a modulation method and device for a current-source inverter. The method comprises the following steps: acquiring a three-phase symmetric reference signal, and carrying out Clark transformation on the three-phase symmetric reference signal, thus obtaining a first sine signal and a second sine signal; carrying out vectorial combination on the first sine signal and the second sine signal, thus obtaining a vectorial combination signal; judging a sector where the vectorial combination signal is located, and if the vectorial combination signal is located in a first sector, calculating bridge arm on-off state time of the first sector; distributing carrier periodic time according to a sequence, and obtaining multiple state change time according to the bridge arm on-off state time of the first sector; carrying out carrier modulation on the multiple state change time, and carrying out on-off vector configuration, thus generating a triggering pulse signal. According to the modulation method for the current-source inverter, an optimal waveform is output according to the distribution of the time sequence, and the number of on-off times and the on-off loss under a voltage reduction mode are the minimum.