15 results about "Ac components" patented technology

The application discloses a motor control method, a controller, a motor, a refrigerator, a medium and a program product. A direct-current bus voltage and a cross-axis current of a motor are acquired, and a direct-axis voltage and a cross-axis voltage are acquired. An initial direct-axis current is generated through field weakening control according to the direct-axis voltage, the cross-axis voltage and the direct-current bus voltage. A target frequency disturbance component caused by direct-current bus voltage fluctuation and a direct-current component used for field weakening control are separated from the initial direct-axis current. A phase of the target frequency disturbance component is calculated and optimized to obtain a target alternating current component, with minimization of a harmonic component of the target frequency in the cross-axis current as an optimization target. A direct-axis reference current is synthesized according to the target alternating current component and the direct-current component, and the motor is controlled according to the direct-axis reference current. In the working condition of the direct-current bus voltage fluctuation, energy backflow can be effectively inhibited, current harmonics can be reduced, torque pulsation can be reduced, and the running stability of the motor can be improved.

This invention discloses an active damping control structure and method for a DC transformer and a DC distribution network, belonging to the field of DC transformer control technology. In the control structure: a summation module sums the input voltages of M sub-modules to obtain voltage v. bus The filter module filters out voltage v bus The AC component in the equation yields the DC voltage v. DC The averaging module calculates the voltage v respectively. bus and DC voltage v DC Divide by M to obtain the reference value v avg and reference value v DCref The input voltage equalization controller realizes the input voltage v of each submodule j. in_j Compared with reference value v avg Zero steady-state error regulation, output power p ivs_j The input voltage regulator controller implements the input voltage v of each submodule j. in_j Compared with reference value v DCref Zero steady-state error regulation, output power p ivr_j The output voltage regulator achieves the output voltage V. o Compared with reference value V oref Zero steady-state error regulation, output power regulation p ove The actual power calculator calculates the actual power of each submodule j using the instruction p. pu_j The control structure and method of this invention ensure stable operation of the transformer.

This invention discloses an active simulation system and method for harsh ground planes in DC testing, belonging to the field of electromagnetic environment simulation technology in electrical testing. The system employs a dual DC source architecture with a grounding switch. Two DC sources are connected to the DC power supply circuit of the device under test (DUT), and the grounding switch enables controllable switching between the dual DC sources and the ground plane. By configuring the DC output of the two DC sources and superimposing controllable ripple, while ensuring zero AC component of the voltage between the positive and negative terminals of the DUT and stable power supply, the voltage between the ground plane and the negative terminal of the DUT forms independently adjustable DC and AC components. It also provides two implementation architectures that can flexibly adapt to different testing scenarios. This invention achieves full-parameter active controllable simulation of harsh DC ground planes, accurately reproducing the actual operating conditions of DC tests such as power batteries, motor test benches, and high-power charging and discharging, significantly improving test quality and the verification accuracy of the safety and reliability of the DUT.

The present application discloses a failure detection circuit and a failure detection device, which includes a switching circuit, a bias control circuit, and a fault detection circuit. The switching circuit has a first terminal, a second terminal, and a control terminal, and connects or disconnects the first and second terminals according to a control terminal voltage. The bias control circuit is coupled to the switching circuit and changes the control terminal voltage according to a fault signal. The fault detection circuit is coupled to the bias control circuit, detects an AC component in the control terminal voltage, and generates a fault signal according to the AC component. The fault detection circuit receives a detection signal, compares the detection signal, and generates a detection result signal. When the detection result signal is a fixed level signal or non-ripple signal, the fault detection circuit generates a fault signal.

This invention discloses a DC suppression circuit structure, a DC suppression method, and a terahertz heterodyne detection system. The DC suppression circuit structure includes a first nonlinear detection module, a second nonlinear detection module, a phase adjustment module, and a signal synthesis module. The phase adjustment module adjusts the phase of the mixing signal generated by the second nonlinear detection module. The signal synthesis module superimposes the phase-adjusted mixing signal with the mixing signal generated by the first nonlinear detection module. During the synthesis process, the self-mixing DC component is at least partially canceled out, and the intermediate frequency AC component is at least partially superimposed. This invention weakens or cancels the self-mixing DC component during the synthesis process, while allowing the intermediate frequency AC component to be superimposed and output, thereby effectively suppressing the self-mixing DC component in the output signal and improving the stability of the intermediate frequency signal.

The present application relates to the technical field of permanent magnet synchronous motor control, and particularly relates to an adaptive method for actively feeding forward and compensating cogging torque of super-multipole permanent magnet synchronous motor, which is as follows: a cogging torque feedforward compensation model is established, and the amplitude-phase nonlinear parameters are converted into linear weight coefficient form through triangular orthogonal decomposition; secondly, the AC component of the q-axis voltage output by the current PI regulator is extracted as a compensation residual error signal, the weight coefficient is updated on-line and iteratively using the normalized least mean square algorithm, and adaptive tracking of the cogging torque change caused by temperature drift and mechanical wear is realized; finally, combined with a dual-redundant position feedback system, a double-channel independent weight coefficient maintenance, cross-checking and seamless fault switching mechanism is established. The present application can reduce torque ripple under low-speed working conditions, improve the low-speed stability and control accuracy of super-multipole permanent magnet synchronous motor, and meet the functional safety requirements of aviation-grade electric drive systems.

This invention discloses a method for calculating noise through direct coupling between a worm gear structure and its acoustic field, belonging to the field of noise prediction technology for mechanical transmission systems. The method includes: decomposing the time-domain torque into DC and AC components; establishing a structure-acoustic field coupled finite element model with a matching layer (PML); solving for steady-state prestress using the DC component; treating the AC component as a disturbance under prestress, and directly solving the coupled dynamic equations through harmonic response to obtain the full-field sound pressure response in one step; finally, extracting the sound pressure level distribution to achieve noise prediction. This invention overcomes the shortcomings of the traditional "two-step method" (cumbersome process, neglecting the acoustic radiation of the worm gear itself) by linearizing the prestress and using a one-step direct coupling solution, achieving fast and high-fidelity noise prediction under steady-state conditions, significantly improving computational efficiency and accuracy.

This application provides a method and apparatus for controlling the AC and DC current components of a converter arm current. First, the DC and AC components of the arm current are calculated based on the effective value of the arm current and the effective value of the load branch current. Then, the corrected phase angle difference of the arm voltage and the corrected modulation ratio of the converter are calculated based on the DC and AC components of the arm current. Finally, the converter is controlled based on the corrected phase angle difference of the arm voltage and the corrected modulation ratio of the converter. This application eliminates the need for complex coordinate transformations and multi-loop decoupling, significantly reducing crosstalk between AC and DC components. Furthermore, this application uses the effective value of the arm current and the effective value of the load branch current to calculate the DC and AC components of the arm current, eliminating multiple filtering and closed-loop delay, thus significantly improving transient response speed.

This invention belongs to the field of photovoltaic grid-connected technology and discloses a method for calculating the ESR of photovoltaic inverter capacitors based on EMD. The method includes: performing Empirical Mode Decomposition (EMD) on the sampled DC signals of the photovoltaic array output current, boost converter inductor current, and grid-connected inverter inductor current to select n high-content IMF AC components; selecting the IMF AC component with the least correlation to the IMF AC component of the photovoltaic array output current from the n high-content IMF AC components of the boost converter inductor current as the input capacitor feature IMF1; selecting the IMF AC component with the least correlation to the IMF AC component of the boost converter inductor current from the n high-content IMF AC components of the grid-connected inverter inductor current as the DC bus capacitor feature IMF2; and calculating the capacitor ESR based on the input capacitor feature IMF1 and the DC bus capacitor feature IMF2. This method does not require interrupting the normal operation of the photovoltaic inverter and has advantages such as low cost, unified monitoring, and strong anti-interference.

The present disclosure provides a monitoring method for monitoring a DC bus capacitor, including steps of: in a preset cycle, sampling an input voltage, an input current and an output voltage to obtain an input power; filtering the input power and the output voltage to obtain an AC component of the input power and an AC component of the output voltage; calculating a capacitance according to the DC component of the output voltage, the AC component of the input power and the AC component of the output voltage; obtaining a total weight coefficient corresponding to the capacitance; and outputting a monitoring capacitance of the DC bus capacitor according to the plurality of the capacitance calculated and obtained in a plurality of the preset cycles and the plurality of the total weight coefficients corresponding to the plurality of capacitance.

The present application provides a DC bus capacitor monitoring method and device. The DC bus capacitor monitoring method comprises the following steps: sampling input voltage, input current and output voltage in a preset period, and obtaining input power; filtering the input power and the output voltage to obtain AC component of the input power and AC component of the output voltage; calculating the capacitance value according to the DC component of the output voltage, the AC component of the input power and the AC component of the output voltage; obtaining the total weight coefficient corresponding to the capacitance value according to at least one of the AC component of the input power, the AC component of the output voltage and the working temperature of the DC bus capacitor; and outputting the capacitance monitoring value of the DC bus capacitor according to the capacitance values obtained in multiple preset periods and the total weight coefficients corresponding to the capacitance values.

This application provides a test circuit and energy storage system. The test circuit includes a controller and a clamping circuit. The clamping circuit is electrically connected to the busbar inside the high-voltage cascaded energy storage unit to be tested. The controller is electrically connected to the busbar. The high-voltage cascaded energy storage unit includes an energy storage unit and a converter unit. When the clamping circuit is located inside the casing of the energy storage unit or converter unit to be tested and is electrically connected to the casing, the controller is used to acquire the test voltage between the casing and the busbar, and the voltage of the AC signal transmitted by the single-phase high-voltage line electrically connected to the high-voltage cascaded energy storage unit. Based on the AC component of the test voltage and the voltage of the AC signal, the insulation state between the casing and the energy storage unit or converter unit is determined, and the insulation level change state is determined accordingly. This helps staff to perceive insulation risks in advance and reduce the risk of accidents.

The application belongs to the technical field of power electronic transformers, and discloses a PET capacitor voltage ripple suppression system and method based on a three-port active bridge. The method uses a three-port active bridge TAB as an isolation stage of an MMDTC-PET, and uses the characteristics that the power AC component amplitudes of the upper and lower bridge arms of an HBSM are equal and the phases are opposite. Under the same phase shift modulation, the two active bridges of the three-port active bridge TAB and the upper and lower bridge arms of the HBSM modular DC chain form a switching capacitor circuit, so that the capacitor ripple current of the two active bridges of the three-port active bridge TAB automatically flows to the next stage. The power AC components are offset at the secondary side of the three-port active bridge TAB. The application does not need to increase the capacitance to suppress the ripple voltage, reduces the cost, and improves the power density.

This invention relates to the field of current calibration technology, specifically to a calibration method and apparatus for an online monitoring device for AC / DC grounding current of a transformer. The method includes: acquiring the grounding current of the grounding circuit in the transformer and performing spectrum analysis; indexing a preset sensor error calibration table to obtain the corresponding amplitude correction coefficient and phase compensation value; generating a canceling current opposite to the AC component of the grounding current and injecting the canceling current into the grounding circuit; monitoring the residual current in the grounding circuit in real time, iteratively correcting the canceling current using a closed-loop feedback method until the AC component in the residual current is less than a preset current threshold, and the fluctuation of the DC component in the residual current meets a preset fluctuation condition, thus determining that the comprehensive calibration permitting condition is met; injecting a standard calibration current into the grounding circuit, recording and analyzing the detection values ​​of the grounding circuit by the online monitoring device to obtain the calibration result of the AC / DC grounding current, thereby improving the calibration accuracy of the online monitoring device for AC / DC grounding current.

This invention belongs to the field of photovoltaic grid-connected technology and discloses a method and system for online estimation of the center temperature of the DC bus capacitor in a photovoltaic inverter. It includes: sampling the instantaneous voltage value v of the DC bus capacitor. cf (t) and the instantaneous value of the grid-connected current i0(t), take the absolute value of i0(t) to get i1(t), and then perform a 90° phase shift to get i2(t); S2. Based on the AC component i1(t) 1ac (t) and v cf (t) Calculate the equivalent series resistance R0 of the DC bus capacitor; S3. Based on the AC component i2(t) 2ac (t) Calculate the real-time capacitance value C0 of the DC bus capacitor; S4. Compare C0 with the capacitance reference value C ref S5. Compare and estimate the degree of degradation of the DC bus capacitor; S6. Correct R0 according to the degree of degradation to obtain the equivalent series resistance correction value R1; S7. Based on the functional equation f of the DC bus capacitor temperature-ESR curve. C (R) and R1 estimate the center temperature of the DC bus capacitor. This method does not require the introduction of new measurement points or interruption of the normal operation of the photovoltaic inverter, and has the advantages of low cost, real-time monitoring, and autonomous monitoring.