Abstract: Provided are a hydraulic control valve, a hydraulic control system, and a transmission. The hydraulic control valve includes a valve body, a slidable valve cartridge, and a pressing mechanism. A valve hole, a first oil supply port, a second oil supply port, and an oil discharge port are formed at the valve body, and each of the first oil supply port, the second oil supply port, and the oil discharge port is in communication with the valve hole. Both the slidable valve cartridge and the pressing mechanism are accommodated within the valve hole. The slidable valve cartridge has a small end close to an end of the valve hole and a large end abutting against the pressing mechanism. The pressing mechanism is disposed at another end of the valve hole.

Abstract: A method of modulating a cascaded three-phase VFD, including: obtaining space voltage vectors according to states and output levels of switches of power units in each stage, and dividing the vectors into large vectors, medium vectors, small vectors and zero vectors according to their lengths; arranging the vectors into a vector space, and dividing the vector space into sectors, wherein each sector corresponds to a group of the large vector, the medium vector, the small vector and the zero vector; determining a sector in which a reference voltage vector is located, wherein the reference voltage vector is composed by the group of vectors; calculating action time of the vectors in the group; allocating an action order to the vectors; and generating a three-phase modulated wave signal based on the action orders and the action time.

Abstract: A dead zone compensation circuit includes: a coordinate transformation module configured to perform a coordinate transformation on three-phase output currents of the three-phase frequency converter based on a given angle, for transforming the three-phase output currents from a three-phase static coordinate to a two-phase rotary coordinate to obtain a reactive current component of the three-phase output currents; a filter module configured to obtain a reactive current fluctuation amount; an error calculation module configured to calculate an error between the reactive current fluctuation amount and a zero value; a regulation and control module configured to regulate and control the reactive current fluctuation amount based on the error, for obtaining a voltage regulation variation; and a summing module configured to add the voltage regulation variation to a reference voltage, for obtaining a regulated voltage, the regulated voltage being used to generate a driving signal for the three-phase frequency converter

Abstract: A dead zone compensation circuit includes: a coordinate transformation module configured to perform a coordinate transformation on three-phase output currents of the three-phase frequency converter based on a given angle, for transforming the three-phase output currents from a three-phase static coordinate to a two-phase rotary coordinate to obtain a reactive current component of the three-phase output currents; a filter module configured to obtain a reactive current fluctuation amount; an error calculation module configured to calculate an error between the reactive current fluctuation amount and a zero value; a regulation and control module configured to regulate and control the reactive current fluctuation amount based on the error, for obtaining a voltage regulation variation; and a summing module configured to add the voltage regulation variation to a reference voltage, for obtaining a regulated voltage, the regulated voltage being used to generate a driving signal for the three-phase frequency converter

Abstract: A method of modulating a cascaded three-phase VFD, including: obtaining space voltage vectors according to states and output levels of switches of power units in each stage, and dividing the vectors into large vectors, medium vectors, small vectors and zero vectors according to their lengths; arranging the vectors into a vector space, and dividing the vector space into sectors, wherein each sector corresponds to a group of the large vector, the medium vector, the small vector and the zero vector; determining a sector in which a reference voltage vector is located, wherein the reference voltage vector is composed by the group of vectors; calculating action time of the vectors in the group; allocating an action order to the vectors; and generating a three-phase modulated wave signal based on the action orders and the action time.

Abstract: The present invention discloses a cascade type power conversion device and a communication system for the same. Each phase of the cascade type power conversion device comprises a plurality of power modules connected in series and a communication system. The communication system comprises a plurality of low voltage communication units and a plurality of optical fibers. The plurality of low voltage communication units are connected in series and disposed in the plurality of power modules, respectively. And the plurality of optical fibers are connected between the low voltage communication units and a master control system of the cascade type power conversion device.