33results about How to "Realize four-quadrant operation" patented technology

The invention relates to a novel monopole inverting circuit capable of boosting voltage, and topology is shown in an attached figure. Besides a three-phase switch bridge (B) of the conventional voltage type inverter, the circuit is additionally provided with a tightly coupled inductor consisting of inductors (L1, L2), a capacitor (C), an interdiction diode (D) and a switch tube (T) for an energy feedback passage (can be removed if no energy is needed to feedback). The voltage boosting control mode of the circuit to an inverter direct current bus uses the state of the through zero vector of the upper and lower switch tubes emitted by the three-phase inverter bridge during zero vector to adjust the action time so as to realize the controllable promotion of direct current bus voltage of the input side of the inverter. The inductors (L1 and L2) are tightly coupled, when the inductors are in a state of through zero vector, the inverter is directly communicated, and a DC voltage source (Vs)charges a couple inductor (L1); and when the inductors are in a state of non-through zero vector, the inductors release energy to supply power to the direct current bus of the inverter (B); the voltage of the direct current bus of the inverter is obtained by lapping the voltage of the inductor (L2) and the voltage of the capacitor (C) so as to enable the voltage of the direct current bus of the inverter to be improved, so that the inverter voltage is boosted. The novel monopole inverting circuit capable of boosting voltage only uses a first stage transform circuit, smartly applies through zero vector which is not allowed by the traditional inverter so as to improve the DC busbar voltage of the inverter, realizes the adjustment to the busbar voltage, suits to the variational occasions which need to boost and invert or larger input voltage, and overcomes the shortage of the traditional voltage type inverter, cares nothing for the through caused by the electromagnetic interference and does not need to be inserted into a dead zone.

The invention discloses a high-power brushless doubly-fed machine three-level bidirectional variable-frequency speed regulation system. The system is characterized in that the system consists of a brushless doubly-fed motor and a three-level dual-PWM alternating-current speed regulation system; and the three-level dual-PWM alternating current speed regulation system includes a brushless doubly-fed motor three-level PWM rectification unit and a brushless doubly-fed motor three-level inverter unit. According to the high-power brushless doubly-fed machine three-level bidirectional variable-frequency speed control system of the invention, in the main circuit structure of the three-level dual-PWM alternating current speed regulation system, as for each phase of bridge arm, four power devices are connected in series, and therefore, each power device bears lower voltage compared with a two-level main circuit structure; an rectification end adopts a three-level PWM rectifier, so that directional energy flow can be realized, and the recovery rate of energy can be improved, and the energy loss of the motor alternating-current speed regulation system can be decreased. The high-power brushless doubly-fed machine three-level bidirectional variable-frequency speed regulation system is suitable for high-voltage high-power motor driving application.

The invention relates to alternating-current to direct-current conversion of electric energy, discloses a four-quadrant multilevel current-source converter with a main circuit based on a thyristor and belongs to improvement to the fact that reactive power compensation is needed to be performed additionally caused by the fact that phase current is restricted and phase voltage is delayed due to a phase shift range of a trigger angle ranging from 0 to 180 when two groups of three-phase bridge-paralleled twelve-pulse thyristor circuits are utilized in high-power places. The converter is characterized in that a paralleling reactor in the topology is replaced by a multilevel injection circuit to enable each group of the three-phase bridges to output stepped multilevel pulse direct current and provide zero-current phase-commutation conditions for the thyristor. The multilevel injection circuit consists of multiple units with the same structure, each unit consists of two components with inverse resistant characteristics and a reactor, and cathodes or anodes of the components are connected with a terminal of the reactor to enable each group to structurally be a three-port unit. Consequently, the multilevel injection circuit and the main circuit are coordinated for controlling to provide the zero-current phase-commutation conditions for a main bridge thyristor, so that controlled turn-off of the thyristor is realized, and the whole circuit can possess four-quadrant operating capability.

The invention discloses a three-phase high-voltage cascade type AC (Alternating Current) -DC (Direct Current) -AC bidirectional converter and a control method thereof. The basic cascade unit consists of two back-to-back single-phase bridge type inverters, wherein one single-phase bridge type inverter is used for carrying out PWM (Pulse-Width-Modulation) rectification and voltage stabilization to absorb energy, and the other single-phase bridge type inverter is used for carrying PWM inversion to release energy so as to realize transferring of active energy; and the input stages and the output stages of N cascade units are respectively connected in series, and input cascade multilevel PWM rectification and output cascade multilevel PWM inversion are realized by adopting a multilevel PWM technology. For the structure, high-voltage AC-AC conversion can be directly realized, and two-way flowing of energy can be realized, so that the structure can be widely applied in high-voltage frequency conversion. Compared with the traditional high-voltage frequency converter, the high-voltage cascade type AC-DC-AC bidirectional converter has the advantages that a phase-shifting transformer is not needed, so that high-voltage conversion can be directly carried out; and a PWM (Pulse-Width-Modulation) rectifying technology is adopted, so that rectification with high-power factor is realized and the power quality of a power distribution network is improved.

The invention provides an alternating-current excitation synchronous machine control device and method, and belongs to the field of electromechanical control engineering. According to the method, alternating-current excitation is conducted on a wound-type motor rotor winding through a variable-frequency controller, excitation efficiency is improved by controlling the excitation current of the motor through a rotor, the capacity of the system is decreased to be twenty percent or lower that of the motor, the capacity of the variable-frequency controller is greatly decreased, and device cost is greatly reduced. Active power of the motor running is provided by a stator winding through a power grid, the power factor on the stator side can be controlled to be 1, the speed regulation system is made more reasonable and more efficient through excitation control, and four-quadrant operation is achieved.

The invention discloses a dynamic braking control system of a direct current motor, which comprises direct current motor, a direct current constant voltage source, a torque and rotating speed sensor, a PLC (programmable logic controller) processor, a chopper control board, an IGBT (insulated gate bipolar transistor) power component and a braking control resistance module, wherein a voltage output of the direct current constant voltage source is connected with a voltage input of the direct current motor via the braking control resistance module; the direct current motor is connected with the torque and rotating speed sensor; an output of the torque and rotating speed sensor is connected with an input of the PLC processor; an output of the PLC processor is connected with an input of the chopper control board; an output of the chopper control board is connected with an input of the IGBT power component; and the IGBT power component is in parallel connection with the braking control resistance module. According to the system, the braking control resistance module is cut off by the PLC processor under different conditions, so that rotating speed and torque outputs of the direct current motor change to achieve dynamic braking.