95results about How to "Good pressure equalization effect" patented technology

The invention provides a voltage balancing circuit used for a series super capacitors bank, and the voltage balancing circuit consists of a control logic device and an electrolytic capacitor. The control logic includes a divider circuit, a pulse generating circuit and a switch array. The voltage balancing circuit is connected with a super capacitor to be balanced. When the voltage difference of two adjacent supper capacitors exceeds the set range, the voltage balancing circuit transfers the electric charge from a high-voltage supper capacitor to a low-voltage supper capacitor, until the voltage difference of the high-voltage supper capacitor to the low-voltage supper capacitor enters into the set range. At that moment, the voltage balancing circuit stops working under the control of an internal empowering circuit and enters into a standby mode, and reduces the energy dissipation. The voltage balancing circuit has simple structure and low cost, can be installed easily, can effectively solve the problem that the voltage of a plurality of series super capacitors is not even.

The invention relates to a pressure-sore-preventing cushion capable of automatically regulating the pressure. The pressure-sore-preventing cushion comprises an airbag array composed of a plurality of airbags, a plurality of air channels, a base, a plurality of air guide pipes and an automatic pressure adjusting device, wherein the airbag array is divided into four airbag regions; all the airbags in each airbag region are communicated with one another; the airbags of any two adjacent airbag regions are not communicated; the plurality of air channels are located below the airbag array; each air channel is connected with at least one of the airbag regions and is communicated with the airbag region; the airbag array composed of the plurality of airbags and the plurality of air channels are arranged on the base; the plurality of air guide pipes are arranged in the base; one end of each air guide pipe is communicated with the corresponding air channel and the other end of each air guide pipe extends out of the cushion and is provided with a connector; each air guide pipe is provided with a respective valve; fluid of the automatic pressure adjusting device is communicated with all connectors of the plurality of air channels and is electrically connected with each valve on each air guide pipe so that the pressure adjusting device can inflate or deflate each air guide pipe.

In control circuit of half bridge convertor, after bias voltage at middle point of capacitance is leaded in circuit of bias voltage at middle point of capacitance composed of proportional integral controller, current generated is fed forward to current comparator. With being leaded in voltage comparator, the reference voltage and feedback voltage are connected to voltage regulator to generate given current, and then connected to the current comparator. The current feedback signal, current feedforward and given signals through the current comparator are connected to hysteresis comparator (or carrier comparator). The hysteresis comparator through the drive circuit controls the main circuit of convertor. The said bias voltage feedforward control and inductive current in half bridge convertor create part of DC component, which balances amperesecond value so as to remove DC bias in voltage at middle point of capacitance.

The invention discloses a three-phase symmetric topology for self-balance of capacitor voltage of an MMC (Modular Multilevel Converter) module. A half-bridge type MMC topology comprises inner-phase module capacitor self-circuits and inter-phase subsidiary loops. An inter-phase self-voltage-sharing circuit consists of 6(N-1) clamping diodes; and in switching of modules, unbalanced voltage of capacitors of the modules automatically flows from an i module to an (i-1) module, wherein the value of i is 2-(N-1). Each of the inter-phase subsidiary loops consists of six subsidiary capacitors, six subsidiary IGBTs (Insulated Gate Bipolar Translator) and nine subsidiary diodes, and a first module of a per-phase upper bridge arm and a last module of a per-phase lower bridge arm form two triangles by the inter-phase subsidiary loops, thereby realizing free flow of inter-phase energy. According to the topology disclosed by the invention, the self-balance of the inner-phase and inter-phase energy is realized; all the modules adopt identical sub-modules, thereby keeping consistency of the modules; and the inter-phase subsidiary loops at the two ends form the triangles, thereby keeping the symmetry of the three-phase topology.

The invention provides an automatic control pressure-equalizing fire preventing and extinguishing system in a large area. Master control equipment is used for transmitting signals of air pressures at two ends of an air leakage channel in a pressure-equalizing area and a signal of pressure difference of two sides of an air window to an upper industrial control computer and transmitting a command for adjusting the current frequency and a command for adjusting the air window according to a control command for pressure-equalizing adjustment transmitted by the upper industrial control computer; the upper industrial control computer is used for determining whether to transmit a control command for pressure-equalizing adjustment to the master control equipment or not according to the signals of the air pressures at the two ends of the air leakage channel and the signal of the pressure difference of the two sides of the air window; a first frequency converter is used for adjusting the rotating speed of a fan and the outlet air pressure according to the command for adjusting the current frequency; a second frequency converter is used for controlling a stepper motor to regulate the opening area of the air window according to the command for adjusting the air window. According to the automatic control pressure-equalizing fire preventing and extinguishing system provided by the invention, the revolution number of the fan and the air passing port area of the air window can be automatically controlled and adjusted, so that the pressure-equalizing area is always kept in a pressure balancing state, and the problem that the pressure-equalizing area is not equalized in pressure due to poorer precision and timelinesses is solved.

The invention relates to a pressure sore prevention seat cushion. The pressure sore prevention seat cushion comprises an airbag layer, an airway layer, a base layer and a plurality of air conduits; the airbag layer is provided with a plurality of airbags; the airbag layer is divided into at least four airbag regions; all the airbags in each airbag region are communicated mutually, however, the airbags in any two adjacent airbag regions are not communicated; the airway layer is positioned below the airbag layer, and a plurality of airways are formed in the airway layer, wherein each airway is connected and communicated with at least one airbag region; the airway layer and the airbag layer are arranged on the base layer; one end of each air conduit is communicated with the corresponding airway and the other end of the air conduit extends out of the seat cushion and is provided with a joint; each air conduit is provided with a respective valve. The pressure sore prevention seat cushion disclosed by the invention can enable the hip of a human body to be intermittently pressed so as to effectively prevent pressure sores.

The invention provides an optimized merging and sorting based modular multilevel converter capacitor voltage equalizing method, which is characterized in that a merging and sorting algorithm is optimized through analyzing a capacitor voltage law of nearest level modulation in an ideal condition by using a modular multilevel converter modulation technology, the time complexity of optimized merging and sorting is further reduced, the execution time of actual sorting is reduced to the minimum, the sorting efficiency is very high, and sorting is not restricted by the number of sub-modules. In addition, a non-ideal condition correction optimized merging and sorting algorithm is provided by combining a direct insertion sorting method, the sorting accuracy can be ensured by correcting the optimized algorithm, the voltage equalizing effect is good, and the extra time overhead is small.

The invention provides a doubly-fed frequency converter and a modulation method thereof, the doubly-fed frequency converter comprises a three-phase bridge arm and a control unit, and each phase bridgearm comprises a first switch module, a second switch module, a third switch module, a fourth switch module, a fifth switch module and a sixth switch module. The control unit controls the on and off of the first switch module, the second switch module, the third switch module, the fourth switch module, the fifth switch module and the sixth switch module, thereby enabling each phase of bridge arm to enter a positive half-wave period state, a positive dead zone state, a positive zero state, an all-zero state, a negative zero state, a negative dead zone state and a negative half-wave period state.

The invention discloses a cable insulation comprehensive diagnosis and test system, which comprises a high-voltage generating unit, a high-voltage switch, a high-voltage electric reactor, a capacitivevoltage divider, a PC control unit and a partial discharge coupling capacitor, wherein the PC control unit is connected with the high-voltage generating unit, the high-voltage switch and the partialdischarge coupling capacitor separately, an output end of the high-voltage generating unit is connected with input ends of the high-voltage switch and the high-voltage electric reactor, an output endof the high-voltage electric reactor is connected with an input end of the capacitive voltage divider and a tested cable separately, and an output end of the capacitive voltage divider is connected with an input end of the partial discharge coupling capacitor; and the upper ends of the high-voltage electric reactor and the capacitive voltage divider are each provided with a voltage equalizing mechanism. The cable insulation comprehensive diagnosis and test system has the advantages of convenient installation and capability of improving voltage equalization effect.

The invention discloses a twelve-phase three-level H-bridge direct-current side cascade propulsion frequency converter which is formed by cascading the direct-current sides of two six-phase three-level H-bridge propulsion frequency converters, wherein the cascade upper-end propulsion frequency converter is provided with a non-return diode at a direct-current input positive electrode, the cascade lower end propulsion frequency converter is provided with a non-return diode at a direct current input negative electrode; the three-level H-bridge direct-current side cascade topology suitable for direct-current 10kV is developed based on a mature three-level H-bridge topology, and compared with other five-level or modular multi-level topologies, the three-level H-bridge direct-current side cascade topology does not involve an absorption loop or a complex large commutation loop, and is provided with a simple main circuit. The invention further discloses a capacitor voltage balance control method; neutral-point potential adjustment based on zero-sequence voltage injection is adopted; three-level upper and lower H bridges are adjusted through loads; and themethod is easy to implement and does not affect an original control strategy.

The invention discloses a half-V-shaped suspension string for preventing windage yaw. The half-V-shaped suspension string sequentially comprises an overhanging yoke plate, a yoke plate, a pillar insulator string and an I-type insulator, an iron tower cross arm arranged from bottom to top. The suspension yoke plate is connected with a yoke plate. The yoke plate is respectively connected with the post insulator string and the I-shaped insulator string, an acute included angle is formed between the lower end of the post insulator string and the lower end of the I-shaped insulator string, the postinsulator string and the I-shaped insulator string are both connected with an iron tower cross arm, and the I-shaped insulator string is vertically connected with the iron tower cross arm. The structure can ensure that the air gap between the wire and the iron tower does not exceed the limit under severe weather conditions such as sand storm, thereby being suitable for the side phase of the powertransmission line straight line iron tower in a gale area, preventing the overhead power transmission line from windage yaw flashover, avoiding large-area power failure accidents, and improving the power supply reliability of a power grid.

The invention discloses a high voltage wall bushing which comprises an electricity conducting rod, an inner insulation layer surrounding the middle part of the electricity conducting rod, a connecting flange arranged on the inner insulation layer and an increase climbing outer insulation layer sleeved on the inner insulation layer and positioned at both sides of the connecting flange, and the connecting flange is glued and fixed on the outer wall of the inner insulation layer by an adhesive. In the invention, the processing and manufacturing are both convenient, resources are saved, and the cost is low.