37results about How to "Eliminates DC bias" patented technology

The invention provides an impedance identification method of a power grid of a grid-connected inverter based on high-frequency signal injection. The method comprises the following steps: firstly, respectively measuring the voltage and bridge arm side current of the grid-connected inverter by using a voltage sensor and a current sensor, and converting the voltage and the bridge arm side current through a proportional integral controller to obtain a modulated voltage signal; then, injecting a three-phase high-frequency voltage signal into the modulated voltage signal to update the voltage of thegrid-connected inverter, measuring the power grid side current of the grid-connected inverter by using the current sensor, and respectively substituting the updated voltage and the power grid side current into a voltage extraction module and a current extraction module; and finally, extracting a high-frequency voltage signal and a high-frequency current signal of a grid of the grid-connected inverter by using an improved complex number filter so as to solve an impedance value of the power grid in real time. According to the impedance identification method provided by the invention, the three-phase high-frequency voltage signal is directly superimposed on the modulated voltage signal, thereby ensuring the effective injection of the high-frequency signal and being able to improve the signal-to-noise ratio of the power grid, so that the impedance identification accuracy of the power grid is improved.

The invention discloses a photodiode circuit based on background noise elimination and a laser ranging system. The photodiode circuit based on background noise elimination, provided by the invention, comprises a photodiode transconductance amplifier module, an operational amplification integrator module and a filtration module, wherein the filtration module is connected to the output end of the photodiode transconductance amplifier module and the input end of the operational amplification integrator module; and the output end of the operational amplification integrator module is connected to the input end of the photodiode transconductance amplifier module. According to the photodiode circuit disclosed by the invention, only an operational amplifier, a capacitor and a resistor can be used by the operational amplification integrator module, only a capacitor and a resistor can be used for a filter circuit, a digital element is not used in the whole circuit, extra noise is avoided, the signal to noise ratio of the circuit can be greatly improved, and the ranging range is widened. Meanwhile, because only the operational amplifier, the resistor and the capacitor are used, the cost is greatly reduced compared with the prior art, and the overall circuit area is greatly reduced, so that miniaturization of the product is facilitated.

The invention provides a rapid power commutation control method for a dual-active full-bridge DC / DC converter, and the method comprises the steps: S1, defining that power is transmitted from a primary side to a secondary side of the dual-active full-bridge DC / DC converter as positive transmission, and otherwise, the power is transmitted as negative transmission; s2, according to an initial power value and a target power value set by a user, judging how to change the direction of the transmission power, and according to known parameters, respectively calculating the required phase shift difference duty ratio sum between the primary side square wave voltage and the secondary side square wave voltage of the high-frequency transformer; and S3, calculating the negative pulse width duty ratio of the adjusted primary side square wave voltage of the high-frequency transformer and the positive pulse width duty ratio of the adjusted secondary side square wave voltage of the high-frequency transformer in the transient process so as to finish conversion from an initial power value to a target power value, eliminate direct current bias and realize soft switching. The equivalent resistance is considered during modeling and analysis, so that the risk that components are damaged can be further reduced, and the stability of the converter is improved.

The invention relates to a fixed on-time controller for a switch power supply and with an inductance and current slope compensation function. The switch power supply comprises an MOSFE switching tube and a filter inductor, the fixed on-time controller comprises an RS trigger, a time delayer and a comparator, the time delayer is connected with the RS trigger, the output end of the RS trigger is connected with the MOSFE switching tube, the input end of the RS trigger is connected with the output end of the comparator, one input end of the comparator is connected with the output end of the switch power supply, the other input end of the comparator is connected with a direct-current bias correction circuit, the direct-current bias correction circuit comprises a subtracter, an inductance and current feedback bypass and reference voltage, one end of the substrater is connected with the comparator, and the other end of the substrater is connected with the inductance and current feedback bypass and the reference voltage. Compared with the prior art, the fixed on-time controller has the advantages of precisely controlling output voltage and the like.

The invention discloses a DC bias suppression method for a bidirectional full-bridge DC / DC converter, which belongs to the field of circuit control of a bidirectional full-bridge DC / DC converter. The suppression method includes: calculating the required phase shift angle after power change , in the first cycle after the required power change, quantitatively change the phase shift angle and duty cycle of the secondary side, and start to work with a steady-state phase shift angle in the second cycle after the required power change . The invention controls the voltage of the AC side of the secondary side in one cycle so that the current flowing through the transformer can quickly recover to the steady current after the power change, and eliminates the DC bias in the recovery process, thereby suppressing the bias magnetism. The application of bridge DC / DC converter circuit in the occasion of power change is of great significance.

The invention discloses an intermediate-frequency and radio-frequency universal target simulator for a pulse pressure radar. The target simulator comprises a power supply module, a reference source generating module, a control display module, an intermediate frequency analog signal generating module, an amplitude regulating module and a hybrid frequency filtering module; the amplitude regulating module is divided into amplitude regulating modules A and B; the hybrid frequency filtering module is divided into hybrid frequency filtering modules A and B; the power supply module is connected withother modules; the reference source generating module is respectively connected with the control display module and the intermediate frequency analog signal generating module; the control display module is respectively connected with the intermediate frequency analog signal generating module, the amplitude regulating module A and the amplitude regulating module B; the intermediate frequency analog signal generating module is respectively connected with the amplitude regulating module A and the amplitude regulating module B; the amplitude regulating module A is connected with the hybrid frequency filtering module A; and the amplitude regulating module B is connected with the hybrid frequency filtering module B. The target simulator provided by the invention has the advantages of simplifiedcircuit, pure frequency spectrum, integrity of the intermediate frequency and the radio frequency, abundant functions, real data and strong pertinence.

The invention provides an impedance identification method of a power grid of a grid-connected inverter based on high-frequency signal injection. The method comprises the following steps: firstly, respectively measuring the voltage and bridge arm side current of the grid-connected inverter by using a voltage sensor and a current sensor, and converting the voltage and the bridge arm side current through a proportional integral controller to obtain a modulated voltage signal; then, injecting a three-phase high-frequency voltage signal into the modulated voltage signal to update the voltage of thegrid-connected inverter, measuring the power grid side current of the grid-connected inverter by using the current sensor, and respectively substituting the updated voltage and the power grid side current into a voltage extraction module and a current extraction module; and finally, extracting a high-frequency voltage signal and a high-frequency current signal of a grid of the grid-connected inverter by using an improved complex number filter so as to solve an impedance value of the power grid in real time. According to the impedance identification method provided by the invention, the three-phase high-frequency voltage signal is directly superimposed on the modulated voltage signal, thereby ensuring the effective injection of the high-frequency signal and being able to improve the signal-to-noise ratio of the power grid, so that the impedance identification accuracy of the power grid is improved.

The invention discloses a method, a device and a storage medium for suppressing a DC bias of a DAB converter, and relates to the control field of a bidirectional active bridge DC-DC converter. The method for suppressing a DC bias of a DAB converter includes: obtaining a DAB The first external phase angle between the two full bridges in the previous stable state of the transient process; wherein, the two full bridges output the first square wave and the second square wave respectively, and the first square wave and the second square wave The phase difference value between the square waves is the first external shift phase angle; when entering the DAB transient process, change the pulse width of the first square wave and the second square wave respectively; according to the first square wave after changing the pulse width Square wave and second square wave, get the phase shift angle. The main purpose of the technical solution proposed by the present invention is to directly change the direction and / or magnitude of power transmission by changing the pulse width of the two square waves during the transient process after the previous steady state, thereby eliminating the traditional DC bias generated by transient process under single phase shift.

The present invention provides a novel general-purpose four-phase-shift modulation method for improving the dynamic performance of dual active bridges. All carrier signals remain synchronized. The general-purpose four-phase-shift modulation method adjusts the corresponding parameters by changing the parameters of the comparison registers in each carrier. phase shift angle. The control method proposed by the present invention is based on the traditional phase-shift control method, and only needs to measure the input and output voltages without adding auxiliary circuits. Compared with other control methods, the method proposed by the present invention completes the dynamic response instantaneously, does not need a transition process, and does not need to detect the inductance current, and the whole control process has nothing to do with the inductance value. The method proposed in the present invention reduces the cost and computational complexity, realizes fast dynamic response of the circuit and eliminates the DC bias of the inductor current during the response process, and at the same time, the method proposed in the present invention can be applied to hard switching, soft switching, unidirectional power transmission, All application scenarios such as two-way power transmission are also applicable to all control methods such as single phase-shift modulation and triple phase-shift modulation.

The invention relates to an alternating current-direct current-alternating current power supply system with transformer power supply for a locomotive or a motor car, in particular to a transformer direct current bias suppression method for the alternating current-direct current-alternating current power supply system of the locomotive. The problems existing in an existing alternating current-direct current-alternating current power supply system of the locomotive in overcoming the transformer direct current bias are solved. When transformer direct current bias suppression method for the alternating current-direct current-alternating current power supply system of the locomotive works through four quadrants, positive accumulation processing and negative accumulation processing of a plurality of power grid cycles are carried out on the input voltage of the four quadrants in the positive and negative half cycle of the power grid voltage. According to the actual working conditions, after the positive and negative half cycle phase intervals of the fundamental wave of the input voltage are accurately calculated, positive accumulation processing and negative accumulation processing of thepower grid cycles are carried out on the input voltage of the four quadrants. Whether direct current bias occurs or not is judged through four quadrant input voltage and current, when the direct current bias occurs, PI regulation is carried out on the accumulated value of the positive and negative half cycle of the current to change the output result of a current loop so as to adjust the PWM pulse width and realize the compensation and suppression of the direct current bias.

The invention relates to a switching power source fixed on-time controller with external compensation. A switching power source comprises an MOSFET switching tube. The fixed on-time controller comprises an RS trigger, a time delayer and a comparator. The time delayer is connected with the RS trigger, the output end of the RS trigger is connected with the MOSFET switching tube, the input end of the RS trigger is connected with the output end of the comparator, one input end of the comparator is connected with the output end of the switching power source, and the other input end of the comparator is connected with a direct current bias correcting circuit. The direct current bias correcting circuit comprises a subtracter, a digital processor and a reference voltage. One end of the subtracter is connected with the comparator, and the other end of the subtracter is connected with the digital processor and the reference voltage. The digital processor and the reference voltage are respectively grounded, and the digital processor outputs the voltage compensation amount to the subtracter. Compared with the prior art, the witching power source fixed on-time controller has the advantages of effectively eliminating direct current bias and being simple in structure.

The invention discloses a locomotive traction power supply system as well as a control method and system of a four-quadrant current transformer. The control method comprises the following steps: obtaining a first sampling current and a sampling voltage at the input end of the four-quadrant current transformer; obtaining a direct-current bias voltage corresponding to an average current value of the first sampling current; overlapping the negative value of the direct-current bias voltage to the sampling voltage so as to obtain a first modulation voltage; controlling the control end of the four-quadrant current transformer according to a first modulation control signal generated by the first modulation voltage. According to the control method, the direct-current bias in a circuit of the four-quadrant current transformer can be removed, the direct-current magnetic bias phenomenon of a traction voltage transformer is avoided, and stable running of the traction voltage transformer and a locomotive traction power supply network is favorably protected.