115 results about "Circuit equation" patented technology

Disclosed is an apparatus for measuring an insulation resistance that may calculate each of a cathode terminal-side insulation resistance value and an anode terminal-side insulation resistance value of a battery. The apparatus for measuring an insulation resistance according to the present disclosure forms different first and second circuits by selectively connecting an insulation resistance measurement unit to a cathode terminal or an anode terminal of the battery, and calculates a cathode terminal-side insulation resistance value and an anode terminal-side insulation resistance value from first and second insulation detection voltages applied to the insulation resistance measurement unit and simultaneous circuit equations derived from the first and the second circuits. Accordingly, quantitative insulation resistance values of the cathode terminal and the anode terminal of the battery may be each obtained.

The invention discloses a grid-connected inverter insulation resistance detecting method. The method aims at solving the problem of multi-way input photovoltaic grid-connected inverter insulation resistance detection, unbalanced bridges are established in a main circuit, a series of circuit equations are generated by detecting changes of the input voltage, an equation set formed by all the equation is solved in the end, and insulation against ground resistance input by each circuit are obtained. The invention further discloses a detecting device for implementing the photovoltaic grid-connected inverter insulation resistance detecting method. Compared with the prior art, the detecting device can carry out accurate measurement on the insulation against ground resistance of each input end of a multi-way input photovoltaic grid-connected inverter, and therefore defects of insulation resistance can be found before hand on the premise that grid-connection exists, and the safety and reliability of grid-connected operation of the photovoltaic grid-connected inverter can be improved; meanwhile, the circuit for implementing the method is simple in structure, easy to achieve, and low in cost.

An angle calculation portion of a motor control apparatus determines an angle θ of a rotor, and an angular velocity calculation portion determines an angular velocity ωe of the rotor. A command current calculation portion determines command currents id* and iq* on dq axes, based on a steering torque T and a vehicle speed S. An open-loop control portion determines command voltages vd and vq on the dq axes based on the command currents id* and iq* and the angular velocity ωe, according to circuit equations of a motor. A dq-axis / three-phase conversion portion converts the command voltages vd and vq to command voltages of three phases. A three-phase voltage correction portion corrects the command voltage so that an actual time average value of a voltage applied to each phase is equal to a time average value of a voltage that is to be applied to the phase if the voltage is not decreased, in order to compensate for a decrease in the applied voltage. By performing the correction, it is possible to eliminate or suppress a decrease in control accuracy due to a wiring resistance and the like.

Provided is a circuit simulation model that can suitably represent capacitor characteristics, thereby realizing accurate circuit design and circuit analysis. A SPICE model is constituted of a capacitor unit in which a capacitor is replaced with a linear voltage dependent current source, a low-pass filter unit that has a function of extracting a DC bias voltage, a calculation circuit unit that is configured by combining an adder, a multiplier, and the like to perform a calculation of a circuit equation derived from an equivalent circuit for a capacitor such as an idealized C circuit model, an RC circuit model, or the like, and a linear voltage dependent voltage source that applies a total voltage applied across the capacitor to the calculation circuit.

The invention provides a three-phase three-column transformer modeling method based on an EIC principle. The method comprises the steps of establishing a corresponding circuit model and a differential magnetic circuit model based on the core topological structure of a three-phase three-column transformer and the parameters of the transformer, deriving a differential inductance matrix, establishing a three-phase three-column transformer bank circuit model, solving a transformer differential circuit equation set according to a numerical algorithm, gaining target variables and establishing an accurate and practical transformer time-domain simulation model. A three-phase three-column transformer model provided according to the method can be used for accurately calculating a low-frequency transient state of the transformer, conducting electric energy quality problem researches, reliably evaluating the direct-current magnetic biasing resistance of the transformer, providing a basis for determining effective and reasonable control measures and providing a basis for power system planning design and equipment type selection.

The invention discloses a method for controlling single-phase inverters by the aid of adaptive current models in a predictive manner, and relates to inversion control on current transformers. The method includes steps of 1), repeatedly acquiring currents of alternating-current sides of the inverters and acquiring measured current values by means of mean filtering; 2), constructing an augmented state space equation by the aid of the measured current values obtained at the step 1) and unknown deviation in circuits, designing Luenberger observers and observing unknown deviation values in the circuits; 3), compensating circuit equations with the unknown deviation values obtained at the step 2), controlling the single-phase inverters by the aid of the models in the predictive manner and accurately tracking currents. The measured current values obtained at the step 1) and the unknown deviation are used as state variables. The Luenberger observers are characterized in that unknown deviation values of the models are equivalent to a slowly varying variable, accordingly, dimensions of the Luenberger observers can be reduced, and the Luenberger observers are convenient to implement. The method has the advantages that accurate current tracking can be realized, current harmonic distortion is small, current robustness is high, transient time is short, and current stability can be fast restored from disturbance.

The invention relates to a DC system insulation monitoring method based on a fixed-frequency switching resistor principle. The method is characterized by comprising steps of low frequency switching resistor branch establishment, DC leakage current measurement carried out through utilizing an AC sensor, calculation based on a circuit equation, and error analysis on current voltage waveform formed through switching, specifically, a switching resistor is utilized to convert a current passing through a transformer into DC rectangular waves; the AC sensor is utilized to realize accurate detection on a branch ten-microamp-grade ground leakage current; a ground resistor and a distribution capacitor are measured through detection and calculation in real time; accurate DC system ground fault monitoring and fault branch positioning are realized, and influence of the distribution capacitor on measurement precision of the ground resistor can be directly avoided. The method has advantages of scientific and reasonable performance, easy realization, strong applicability, high monitoring accuracy and good effects.

The invention provides a design method for a two-way equivalent arc hyperbolic derivative controller of a high-pressure magnetic control type paralleling reactor. The invention provides and utilizes a magnetic circuit two-way equivalent algorithm, describes saturable magnetic circuit characters via arc hyperbolic functions, and calculates an exciting current required by a control system in the manner of analytic solutions from a complex coupled non-linear magnetic circuit and a differentiating circuit equation set. The algorithm is direct and the calculation is precise. The invention has the advantages of strong novelty, rapid tracking, reliable control, and the like. The engineered application of a control module is realized by programming in an electric system complete digital real-time emulation device. The invention provides a necessary emulation tool to a super / extra high-pressure magnetic control type paralleling reactor and the real-time magnetic transient state simulation of the control system thereof and also provides a new way to design a control system for an electric system nonlinear element.

The invention discloses a rotor position detection method of a brushless direct current motor without a sensor. The rotor position detection method of the brushless direct current motor without the sensor comprises a detection method of a rotor start position and a detection method of a rotor position after the motor rotates. According to the detection method of the rotor start position, current relative positions of a coil magnetic field and a permanent magnetic field can be judged according to a law of variation of motor coil magnetic flux along with the permanent magnetic field, specially, symmetric voltage Uvu and Uuv, Uvw and Uwv, and Uuw and Uwu with equal pulse width and the same voltage value are connected with three phase circuits v, u and w of the motor in pairs, the voltage can not enable a rotor of the motor to deflect, the voltage or current of brushless direct current motor coil three phases is sampled, and current relative positions of coil of the rotor and the permanent magnetic field when the motor is started can be estimated according to a voltage circuit equation. According to the rotor position detection method of the brushless direct current motor without the sensor, the position of the rotor can be detected without the requirement for motor rotation, and therefore a current blind starting mode of the brushless direct current motor without a Hall sensor is replaced.

The present invention discloses an electric railway AT (Auto Transformer) traction network AT section fault location method. The voltage phases and the current phases of two ends of a traction networkAT section are measured at the same time, the voltage phases comprise a contact line T head end voltage phase as shown in the description and a head end current phase as shown in the description, a tail end voltage phase as shown in the description and a tail end current phase as shown in the description, and a tail end voltage phase as shown in the description and a tail end current phase as shown in the description, a circuit equation is listed, and a fault position x or D<->x is solved. The method can eliminate the influences of factors such as the structure and the operation mode of the traction network, is suitable for non-metal short-circuit fault condition with large transition resistance, is high in fault location precision, and can be widely suitable for fault location of the electric railway AT traction power supply system.

The invention discloses a fault calibration algorithm for a direct supply traction network of an electrified railway, and relates to the technical field of electrified railway traction power supply. The algorithm comprises the steps: measuring a voltage phasor and a current phasor of two ends of each segment of the direct supply traction network synchronously; listing circuit equations through a head-end voltage phasor, a head-end current phasor, a tail-end voltage phasor and a tail-end current phasor of an uplink contact line T1 and a head-end voltage phasor, a head-end current phasor, a tail-end voltage phasor and a tail-end current phasor of a downlink contact line T2, wherein the above phasors are shown in the description; and solving a fault position x or D-x. The algorithm can eliminate the impact from the structure and operation mode of a traction network, and is suitable for a non-metal short circuit fault condition of a bigger transition resistor, and is high in fault locatingprecision. The algorithm is widely suitable for the fault locating of the direct supply traction power supply system of the electrified railway.

A method of simulating a circuit parameter such as voltage or current for a dominantly linear circuit by constructing a circuit equation matrix whose elements correspond to nodes of the circuit, decoupling linear and nonlinear contributions to the circuit parameter based on a partition of an inverse matrix of the circuit equation matrix, computing linear and nonlinear components using the decoupled contributions, and combining the nonlinear and linear components to yield a state of the circuit parameter for a given time step. The computation of the nonlinear component includes Newton-Raphson iterations to linearize nonlinear devices of the circuit, wherein the Newton-Raphson technique is applied to the right-hand side of the circuit state matrix equation. The computations are iteratively repeated for successive time steps which are advantageously separated by a constant time interval to avoid further recalculation of the state matrix.

The invention discloses an MMC frequency coupling impedance modeling method under model prediction AC voltage control. An MMC under AC voltage control is predicted by using a model to serve as a modeling object; through circuit equation frequency domain small signal modeling and model prediction AC voltage control loop frequency domain small signal modeling, an MMC small signal impedance model isobtained through derivation, and the model is composed of MMC positive sequence impedance, MMC negative sequence impedance and positive sequence impedance and negative sequence impedance frequency coupling terms caused by MMC internal complex harmonic dynamic characteristics. The accuracy of the small signal impedance model established by the method is verified by simulation, and the method and the basis can be provided for MMC small signal impedance modeling and stability analysis based on an MMC system.

The invention provides a current predication control method based on a single-phase Vienna rectifier. The method comprises the following steps: firstly, deducing a circuit equation of the single-phase Vienna rectifier according to Kirchoff's laws and a single-phase Vienna rectifier topological structure; carrying out discrete treatment on the obtained circuit equation to obtain a single-phase Vienna rectifier discrete state equation; calculating a TS(K+2) moment current reference value by utilizing a two-ordered Lagrange's interpolation method and estimating a power grid voltage sampling value by utilizing a linear extrapolation forecasting method; predicating reference current and a periodic average error to obtain next-beat output current; finally, predicating three components to obtain next-beat predicated reference voltage UaN. By adopting the control method provided by the invention, errors caused by delaying control can be eliminated as much as possible, and influences, caused by the delaying control, on current control are improved, so that third-order harmonic and total harmonic distortion problems of power grid current are effectively solved.

The invention relates to a short-circuit current attenuation calculating method with consideration of a dynamic load for a power system. Dynamic and static loads are distributed appropriately according to reactive power requirements of the dynamic load, the electric potential attenuation of a generator and an electromotor is calculated through non-mutation principle of a flux linkage (electric potential) of the generator and the electromotor, the instant flux linkage (electric potential) before the short circuit of the generator and the electromotor serves as an initial value of the flux linkage attenuation calculation, and the short-circuit current attenuation with consideration of dynamic feature of the load is solved according to the attenuation of the flux linkage (electric potential) through writing circuit equation ( linear algebraic equations). The method can be used in research on short-circuit current attenuation features with consideration of the dynamic load, and the calculating result with consideration of the dynamic load is more accorded with the actual short-circuit current condition than the calculating result without consideration of the dynamic load.

The invention discloses a multi-scroll chaotic signal generating device and method based on a Jerk circuit form. The device comprises a circuit channel I, a circuit channel F and a circuit channel G, wherein the circuit channel I comprises a first integrating circuit, a second integrating circuit at the preceding stage of the first integrating circuit and a third integrating circuit at the preceding stage of the second integrating circuit; the circuit channel F comprises a function generator and a fourth gain circuit at the preceding stage of the function generator; and the circuit channel G comprises a first gain circuit, a second gain circuit, a third gain circuit, a fifth gain circuit, a first adder and a second adder, the second adder is arranged at the preceding stage of the first gain circuit and the first adder, and the first adder is arranged at the preceding stage of the second gain circuit, third gain circuit and fifth gain circuit. According to the method and device, a multi-scroll chaotic signal source with the Jerk circuit form is realized via only one sine function circuit module, the circuit structure is simple, and the circuit equation is a Jerk equation which is easy to analyze theoretically and realize.

A sliding mode proportion resonance control method based on a three-phase Vienna rectifier is disclosed. The method is characterized by according to a Kirchhoff law and the topological structure of the three-phase Vienna rectifier, deducing a three-phase rectifier circuit equation; collecting the voltages Uc1 and Uc2 of the upper and lower capacitors of a direct current side, alternating current side currents ia, ib and ic and voltages Ua, Ub and Uc, adding the collected voltages Uc1 and Uc2 of the upper and lower capacitors of the direct current side and acquiring a total voltage Udc, using the difference value of the Udc and a direct current side voltage reference value Udcref to acquire a current reference value idref through a sliding mode controller, introducing into a formula: iqref=0, through 2s / 2r conversion, acquiring i alpha and i beta, carrying out 3s / 2r conversion on the alternating current side currents so as to acquire actual current values i alpharef and i betaref, then,subtracting the i alpharef and the i alpha, and the i betaref and the i beta, through proportion resonance control, acquiring usalpha and usbeta, and through the voltages Ua, Ub and Uc, acquiring theangle theta of a phase-locked loop; and introducing the usalpha, usbeta, a direct current side voltage udc, the alternating current side currents ia, ib and ic, and a middle point voltage signal intoa controller, and finally acquiring a Vienna rectifier switch on-off signal. In the invention, the robustness and the dynamic performance of the Vienna rectifier are increased, the reaction speed ofthe Vienna rectifier is increased too, a direct current side voltage fluctuation is reduced, simultaneously a good anti-load-disturbance capability is possessed.

The invention relates to a method for determining a general model of a three-phase magnetic leakage admittance matrix of a power transformer. The method comprises the following steps: (1) determining a transformer three-sequence model based on parameterization of a transformer connection mode; (2) determining a transformer three-sequence circuit equation and three-sequence node admittance matrix with the parameters of the transformer connection mode; (3) determining the transformer three-phase magnetic leakage admittance matrix with the parameters of the transformer connection mode; (4) determining the general model of the transformer three-phase magnetic leakage admittance matrix with a phase-shifting angle and the parameters of the transformer connection mode; (5) verifying the general model of the transformer three-phase magnetic leakage admittance matrix. For one given actual transformer, a parameter value corresponding to a connection mode of a winding and the phase-shifting angle of the transformer are substituted into the general model, the corresponding three-phase magnetic leakage admittance matrix can be obtained, and therefore, one-by-one derivation for various transformers is avoided. The method has general universality and brings convenience for program implementation and engineering application.

The invention belongs to the field of active power filters, and provides an improved space vector single period control method used for simplifying an integral control system. In order to achieve the purpose, the method comprises the following steps: an active power filter main circuit equation based on a single period control idea is simplified; a three-phase power supply voltage zone regionalization condition judgment table is used for judge that a voltage vector of a three-phase AC is located in a zone I, II or III; on-off state da, db or dc of bridge arms on a corresponding phase can be obtained via a judgment result, and an active power filter single period control equation in the zone I, II and III is obtained; Vm is regulated and controlled through that deviation delta vd of the voltage on the active power filter DC side is regulated by proportional integral (PI), and voltage Vd of the DC side is required to be kept during the regulation process, thus a required active power under the current load condition is obtained. The invention is mainly applied in active power wave filtering.

The invention discloses an uplink and downlink overhead contact line equipment parallel state identification method of a direct feeding traction network, wherein the method belongs to the field of electric railway power supplying technology. Through synchronously measuring a head-end voltage vector and a head-end current vector and a tail-end voltage vector of each segmented contact line of the traction network, a circuit equation is written and a current acquisition position x is solved. When the voltage above two ends of the segment of the direct feeding traction network is in a normal rangeabove 19kV, the formula is used for calculating the current acquisition position x. Through comparing each formula calculating result, a head-end or tail-end parallel condition of each segment of thedirect feeding traction network is determined in an online manner, and the head-end or tail-end parallel conditions comprises four conditions of 1, head-end and tail-end parallel connection; 2, head-end parallel connection and tail-end no parallel connection; 3, head-end no parallel connection and tail-end parallel connection; and 4, head-end and tail-end no parallel connection. The method has advantages of performing identification and early-warning on the operation condition of the direct feeding overhead contact line equipment, realizing real-time monitoring and feedback to the condition change of the traction network, and improving automation level and intelligence level in operation and management of the traction network. Furthermore the method has advantages of high versatility andeasy application.

The invention relates to a method for determining the receiving coil position of an omnidirectional wireless electric energy transmission system. The method comprises the following steps that: utilizing a Kirchnoff voltage law to construct a coupling circuit equation of the transmitting coil and the receiving coil of the omnidirectional wireless electric energy transmission system; according to the coupling circuit equation, determining the equation of load power and total input power of the omnidirectional wireless electric energy transmission system, wherein the equations are superposition magnetic field vector angle equations about the transmitting coil; changing the superposition magnetic field vector angles, measuring total input power corresponding to any two different superpositionmagnetic field vector angles through a measurement tool to obtain the equation of two pieces of total input power; and according to the equation of the two pieces of total input power, solving the superposition magnetic field vector angle when the total input power is a maximum value. Since energy transfer efficiency is simultaneously maximum when the total input power is maximum, when the energytransfer efficiency is maximum, the superposition magnetic field vector angle and the angle of a position where the receiving coil is positioned are the same, and the position of the receiving coil isdetermined.

The invention discloses an electric train and high-resistance fault position discrimination algorithm for a direct-supply traction network, and relates to the technical field of electrified railway traction power supply. The algorithm comprises the steps: measuring a head-end voltage phasor, a head-end current phasor, a tail-end voltage phasor and a tail-end current phasor of a segmented contact line of the direct-supply traction network synchronously, limiting a circuit equation, and solving the position of an electric train and a high-resistance fault position x; dividing current extractionin a normal range where the voltage across two ends of a load line is located into two types: electric train (traction load) and high-resistance fault; determining a current extraction position x as the position of the electric train if the voltage across two ends of the load line is within the normal range and the current extraction position x, calculated through a formula, is in monotone increasing or decreasing, uploading the current extraction position x to an integrated automation substation and an electronic speed controller of a power substation; determining the current extraction position x as the high-resistance fault if the current extraction position x does not change with time and the period when the current extraction position x does not change with time exceed a parking timeperiod, uploading the position to the integrated automation substation of the power substation, giving an alarm, or sending a releasing command.

An angle calculation portion of a motor control apparatus determines an angle θ of a rotor, and an angular velocity calculation portion determines an angular velocity ωe of the rotor. A command current calculation portion determines command currents id* and iq* on dq axes, based on a steering torque T and a vehicle speed S. An open-loop control portion determines command voltages vd and vq on the dq axes based on the command currents id* and iq* and the angular velocity ωe, according to circuit equations of a motor. A dq-axis / three-phase conversion portion converts the command voltages vd and vq to command voltages of three phases. A three-phase voltage correction portion corrects the command voltage so that an actual time average value of a voltage applied to each phase is equal to a time average value of a voltage that is to be applied to the phase if the voltage is not decreased, in order to compensate for a decrease in the applied voltage. By performing the correction, it is possible to eliminate or suppress a decrease in control accuracy due to a wiring resistance and the like.

The invention discloses a new method for estimating and solving the harmonic emission level based on harmonic source independence. The method comprises the following steps: step (A), sampling voltageand current values of a common coupling point in a certain period of time, and establishing a measurement data matrix by using the sampled measurement data; step (B), calculating a covariance matrix of the measurement data matrix in the step (A), simultaneously establishing another expression of the covariance matrix according to a known circuit equation, and establishing an impedance calculationequation according to the corresponding relationship between the two covariance matrix expressions; and step (C), simplifying another expression of the covariance matrix in the step (B) based on the independent characteristics of harmonic sources at both sides of a PCC point, and solving harmonic impedance by an equation set established by corresponding equality of the two covariance matrix expressions.

The invention relates to a sliding mode proportional-resonant control method based on a three-phase Vienna rectifier. The method comprises the steps that a three-phase rectifier circuit equation is derived according to a Kirchhoff's law and a topological structure of the three-phase Vienna rectifier; the voltages Uc1 and Uc2 of an upper capacitor and a lower capacitor on the direct current side, the currents ia, ib and ic on the alternating current side and the voltage Ua, Ub and Uc are collected corresponding, the collected voltages Uc1 and Uc2 of the upper capacitor and the lower capacitor on the direct current side are summed to obtain the total voltage Udc, the difference value of the Udc and the voltage reference value Udcref on the direct-current side is subjected to treatment through a sliding mode controller so as to obtain a current reference value idref, the current reference value idref is substituted into iqref = 0, then 2s / 2r conversion is carried out so as to obtain i alpha and i beta, the alternating-current side currents are subjected to 3s / 2r conversion so as to obtain the current actual values ialpharef and ibetaref, then the difference between the ialpharef and the ialpha and the difference between the ibetaref and the ibeta are obtained, then proportional resonance control is carried out so as to obtain usalpha and usbeta, and the angle theta of a phase-locked loop is obtained through the voltage Ua, Ub and Uc; and the usalpha, the usbeta and the voltage udc on the direct-current side, the current ia, ib and ic on the alternating-current side and a mid-point voltage signal are led into the controller together, and finally a switch-on-off signal of the Vienna rectifier is obtained. According to the method, the robustness and the dynamic performance ofthe Vienna rectifier are improved, the reaction speed of the Vienna rectifier is increased, the voltage fluctuation on the direct-current side is reduced, and meanwhile, better anti-load-disturbanceresistance is achieved.

Provided are a method and apparatus for analyzing a circuit model by reducing, and a computer program product for analyzing the circuit model. The circuit model at least includes independent current source models, resistance models, and capacitance models. Also, the circuit model forms a resistance capacitance (RC) network with independent current sources. The method includes selecting a node to be removed using resistance information and comparing conductance of a capacitor for a given time step and the total conductance of the node. Further, the method includes removing the selected nodes and generating RC elements and independent current sources using adjacent nodes, which maintain the accuracy of node voltages of a circuit reduced in an accuracy order used for entrywise perturbation of the corresponding circuit equation. Moreover, an efficient method of handling the independent current sources while reducing the circuit is provided.

The invention discloses a pulse laser ranging system transistor type receiving circuit error correcting method. The pulse laser ranging system transistor type receiving circuit error correcting methodcomprises the following steps that (10) a circuit modeling is received, wherein a circuit equation set is listed according to a circuit structure and a transistor classic model; (20) a circuit equation set is solved, wherein a numerical value approximation solution of the circuit equation set is solved by means of discretization and numerical analysis; (30) the circuit equation set is simplified,wherein the circuit equation set is reserved according to the numerical value approximation solution of the circuit equation set; (40) a linear differential equation set is solved, the linear differential equation set is solved to obtain an approximate relation between the walking error and the input current; (50) an error relation is determined, wherein a double-threshold moment is substituted into the approximate relation to obtain the relation between the walking error and the double-threshold moment; and (60) time error is corrected, wherein the specific numerical value of the double-threshold moment is substituted into the relation to obtain an error value, and the error value is subtracted from the time interval to obtain an accurate time interval. The error correcting method is small in error and high in system measuring precision.