30results about How to "No need to change the topology" patented technology

The invention discloses a five-phase inverter random SVPWM modulation method, and belongs to the technical field of multi-phase inverter drive control. In every sampling cycle, the sampling cycle is kept constant, a PWM pulse is delayed randomly, to achieve random change of a switch cycle, at the same time, two vector action time obtained through an NFV-SVPWM algorithm are randomly allocated, and double-random of switch frequency and zero vector action time is achieved. According to the five-phase random SVPWM modulation method, on the condition of not influencing low frequency-band harmonic performance, the amplitude of higher harmonic is drastically lowered, harmonic originally concentrated on the switch frequency and around the integral multiple switch frequency is dispersed into a wider frequency spectrum range, thus a more consecutive and even frequency spectrum is obtained, electromagnetic interference and high frequency noise are effectively inhibited, and the electromagnetic compatibility of the system is improved.

The invention discloses a cascaded converter-based multifunctional high-speed switch device which structurally comprises a main switch module, an auxiliary switch K1, an auxiliary switch K2 and an auxiliary switch K3; the main switch module is connected with a power source by the auxiliary switch K1 and is connected with a load by the auxiliary switch K3, and the main switch module is connected with the auxiliary switch K1 and the auxiliary switch K3 with each other in series and is connected with the auxiliary switch K2 in parallel with each other; and the main switch module comprises a cascaded H bridge converter and a wave filtering link, an output end of the cascaded H bridge converter is connected with the wave filtering link, and the cascaded H bridge converter comprises n H bridge converter cascaded units which are connected with one another in series. The cascaded converter-based multifunctional high-speed switch device is flexibly applicable to various connection modes between the power source and the load, has various functions of superspeed switching, voltage compensating, fault current limiting and the like, and is applicable to the middle and high voltage occasion due to a cascaded structure.

The invention discloses a PWM (Pulse Width Modulation) method for suppressing commutation torque ripples of a brushless DC motor, which relates to a DC power supply, a brushless DC motor, a three-phase inverter bridge and a controller, and is characterized in that corresponding PWM measures are adopted to suppress commutation torque ripples through determining a rotating speed range and a commutation stage of the brushless DC motor, and the commutation time of the brushless DC motor is shortened at the same time; and the commutation time has greatly improvements on methods of position-sensorless control and back electromotive force zero-crossing point detection of the brushless DC motor, so that the smooth running performance of the brushless DC motor can be improved at the same time. Commutation torque ripples of the brushless DC motor in the whole speed range are effectively suppressed through selecting an optimal PWM mode in the commutation stage on the basis of PWM modes, the commutation time is shortened at the same time, the control is simple, the implementation is easy, and the smooth running performance of the brushless DC motor is improved. The method provided by the invention does not need to change a topological structure and can be used by slightly changing a software part, and the cost of a hardware system is not increased.

The invention discloses a method for suppressing the commutation torque ripples of a brushless DC motor. The invention relates to the technical field of control technology of brushless DC motors. The method includes the following steps: after entering a break off, conducting upper bridge commutation based on the formula: (as shown in the description) to resolve cycle count of advanced commutation; conducting lower bridge commutation based on the formula (as shown in the description) to resolve cycles of advanced commutation; the PWM cycle count n1 during the ongoing period of the previous Hall signal; the PWM cycle count n2 during the ongoing period of the current Hall signal; when n1-n2 is greater than n upper or n lower, conducting no commutation, and when n1-n2 is not greater than n upper or n lower, conducting commutation: an upper bridge-non-commutation phase duty cycle staying at 1, changing an on-phase duty cycle from 0 to a duty cycle d of an off-phase duty cycle prior to the commutation, the off-phase duty cycle being changed to doff; a lower bridge-non-commutation phase duty cycle staying at d, changing the on-phase duty cycle from 0 to the duty cycle 1 of the off-phase prior to the commutation, the off-phase duty cycle being changed to doff. According to the invention, the method can be applied to a wide range of rotation speeds and load changes and has high electric output power.

The invention discloses a DNP (Distributed Network Protocol) communication access control method based on a neural network. A feature sequence is established by extracting destination addresses, source addresses, directions, primary state flag bits and application layer function codes in a DNP3.0 protocol; the feature sequence is learned by using the neural network, thus obtaining a detection model for access control; a captured data packet is preprocessed, thus obtaining a to-be-detected sequence; and after the to-be-detected sequence is detected by the detection model, whether the data packet is allowed to pass or not is judged, thus finishing DNP3.0 communication access control.

The invention discloses an IEC 60870-5-104 communication access control method. The method comprises the following steps: extracting the first bit of a control field first octet, the second bit of the control field first octet, and the first bit of the control field third octet which are in an IEC 60870-5-104 protocol, a type identifier and a transmission reason as features, learning a specific combination of above features by use of a neural network, thereby obtaining a standard matching rule for access control; and then preprocessing a captured data packet to obtain a to-be-detected sequence, matching the obtained sequence with the standard matching rule to judge whether the data packet is allowed to pass, thereby finishing the IEC 60870-5-104 communication access control.

The invention relates to a data transmission method and system based on intelligent substation clock synchronization. The method includes the following steps: analyzing a message type corresponding toa data stream according to a transmission mode of the data stream; and assigning an output priority to the data stream according to the message type, and mapping the data stream to an output queue ofa corresponding switch for transmission. According to the data transmission method and system based on intelligent substation clock synchronization provided by the invention, through the steps of analyzing the message type corresponding to the data stream according to the transmission mode of the data stream, assigning the output priority to the data stream according to the message type, and mapping the data stream to the output queue of the corresponding switch for transmission, PDEelay_Rep and PDEelay_Resp messages can be preferentially forwarded even if the messages are in a network congestion state, the bidirectional path delay is basically the same, and the final time synchronization accuracy can be greatly improved.

The invention discloses a variable air gap disc-shaped linear induction traction motor high-speed mutual feedback table for track traffic. The device comprises a disc-shaped secondary device, a linear induction motor primary device, a rotary induction motor, a No.1 converter, a No.2 converter, an umbrella-shaped coupler, a primary base, a secondary support table, a rotary coder, a torque meter and a fly wheel. The linear induction motor primary device is fixed on the primary base; the disc-shaped secondary device is rigidly linked with a shaft penetrating through the disc-shaped secondary device; the secondary support table is linked with the shaft by a bearing; the rotary coder is linked with a shaft penetrating through the rotary coder by a bearing; the umbrella-shaped coupler, the fly wheel, the torque meter and the rotary induction motor are serially connected together by a connection shaft in sequence. The No.2 converter is connected with the rotary induction motor; the No.2 converter is connected with the linear induction motor primary device. The variable air gap disc-shaped linear induction traction motor high-speed mutual feedback table for the track traffic has the characteristics of air gap adjusting function, energy saving, comprehensive test on electromagnetic force and work condition, capability of test on high-speed work condition, small size, less space occupation, suitability for indoor use and the like.

The invention provides a flow mirroring system and method realized by hardware and based on an EtherCAT network, and aims to realize undisturbed replication of network flow. According to the method, link layer data in a standard Ethernet model is shunted, and then different processing flows are respectively executed on the two paths of the link layer data, so that the abnormal flow in the networkis monitored while the normal communication requirement of an industrial control system is met. The method is achieved through hardware, the mirroring efficiency is high, processing resources of network communication equipment are not occupied, and the situation that normal communication of the industrial control network is affected by flow mirroring can be effectively avoided; an EtherCAT networkflow undisturbed interception device can be used as a slave station to be directly accessed to a standard EtherCAT network without changing the topological structure of the standard EtherCAT network;compared with a port mirroring mode based on a switch, the number of used ports is reduced, the bandwidth of mirroring ports is not limited, a flow undisturbed interception device does not need to carry out complex configuration operation, and the complexity of flow replication is simplified.