35 results about "RLC circuit" patented technology

A spiking neural network is provided, wherein each neuron of the spiking neural network includes a RC or RLC circuit formed of passive elements. The RC or RLC circuit provides a corresponding spiking function. In some cases, a portion of each neuron of the spiking neural network is implemented in a digital processor and further includes a digital to analog converter between the portion implemented in the digital processor and the RC or RLC circuit. In some cases, the spiking neural network is implemented as a fully analog neural network.

The invention relates to a piezoelectric type negative stiffness collaborative vibration absorption supporting rod for a helicopter rotor dynamic load. The piezoelectric type negative stiffness collaborative vibration absorption supporting rod comprises an upper supporting rod body, a lower supporting rod body and a vibration absorption assembly which is arranged between the upper supporting rod body and the lower supporting rod body and used for vibration isolation. The vibration absorption assembly comprises an auxiliary circular ring used for bearing a static load, a lever spring and a disc spring used for providing negative stiffness and adjustable pre-compression are arranged in the auxiliary circular ring, and a mass block used for absorbing and dissipating vibration energy is arranged below the disc spring; the two sides of the lever spring make contact with the piezoelectric ceramic stack, the piezoelectric ceramic stack is connected with the multi-mode external circuit module, the multi-mode piezoelectric shunt damping effect is formed, and meanwhile a plurality of mode components of the system are controlled. When vibration is large, electric energy is stored, and when vibration is small, the mode is switched to a multi-mode RLC circuit dissipation mode, and mechanical vibration energy is converted into electric energy which is consumed through the circuit. Negative stiffness dynamic low-frequency broadband vibration absorption and piezoelectric shunt multi-mode suppression are coupled, and the effect of efficient vibration isolation is achieved.

The application discloses a transformer operation state self-diagnosis method and system, relates to the technical field of state diagnosis, and comprises the following steps: acquiring and analyzing relevant data in the working state according to test conditions; judging the primary side circuit element state according to the primary side data and an RLC circuit step response time constant formula; calculating the voltage stability according to the secondary side data; calculating the delay duration of the tap switch and the damage degree of the tap switch according to the primary side data; dividing and outputting the state grade; and predicting the first fault time point according to the delay duration and a preset delay duration. The application realizes predictive maintenance by predicting the first fault time point, avoids power failure accidents caused by sudden failures, comprehensively integrates various data of the primary side and the secondary side, combines specific analysis of a circuit model and key components, forms a multi-dimensional and systematic diagnosis system, and realizes comprehensive, intelligent and fine management of the transformer operation state.

The utility model discloses a power line conduction emission environment noise testing device. The device comprises a metal box, a passive load module and a fan heat dissipation module. The passive load module is arranged on the upper portion in the metal box, the fan heat dissipation module is arranged on the lower portion in the metal box, and the passive load module and the fan heat dissipation module are separated through a metal partition plate. The passive load module comprises a first connector, an air switch, a plurality of mechanical voltmeters and a plurality of RLC circuits. The fan heat dissipation module comprises a second connector, a switch, a filter and an electric fan. The load has resistance characteristics, capacitive reactance and inductive reactance effects, the impedance of the load can be adjusted, environmental noise under different load impedances can be detected, whether the environmental noise of a laboratory meets the standard test requirement or not can be effectively detected, the test mode is closer to the test mode of a tested product, the test result is more accurate, and the test efficiency is improved. And the interference of environmental noise on the test of the tested product can be eliminated.

A power converter system is provided. The power converter system includes an energy storage device electrically coupled to a direct current (DC) power source and configured to store electrical energy received from the DC power source, an inverter electrically coupled to the energy storage device, and a pulse width modulation (PWM) filter electrically coupled to the inverter and including a resistor inductor capacitor (RLC) circuit. The power converter system further includes a controller coupled in communication with the inverter and configured to, in an active mode, cause the inverter to convert a DC power signal received from the energy storage device to an alternating current (AC) power signal at an output node of the PWM filter, and in a fast discharge mode, pulse the inverter to cause the DC power signal to be dissipated by the RLC circuit of the PWM filter, substantially discharging the energy storage device.

The invention discloses a method for simulating a dynamic starting characteristic of a low-power Hall thruster, which comprises the following steps of: analyzing a transfer function form of each module, measuring input and output parameters of each module on a thruster entity, and obtaining a transfer function of each module through an MATLAB system identification tool box; rLC circuit structures corresponding to all the modules are designed respectively, transfer functions of the RLC circuit structures are made to be consistent with transfer functions obtained through system identification, parameters of all components of the RLC circuits are calculated, simulation is conducted through simulink, the parameters of the components are further adjusted and optimized, and simulation results are made to be basically consistent with dynamic starting characteristics and steady-state parameters of actually-measured parameters; and finally, the RLC circuits are connected according to the connection relation of all modules of the thruster. The simulated load device can be used for circuit simulation in the development stage of the PPCU and testing in the production stage and the system joint test stage, compared with a pure resistive load, the model can preposition the risk of poor dynamic matching between the PPCU and the thruster, performance optimization of the PPCU product is facilitated, and the iteration efficiency is improved.

This application relates to the field of conductivity measurement technology, specifically to a non-contact conductivity measurement device. It includes a measurement unit, a signal processing unit, a temperature compensation unit, a power supply unit, and a sample container. The measurement unit includes a solenoid, a resistor, and a capacitor connected in series to form an RLC circuit module. The signal processing unit includes an analog-to-digital converter (ADC) and a processor, with the processor connected to the measurement unit via the ADC. The temperature compensation unit is connected to the processor and used to monitor the ambient temperature. The power supply unit is connected to the measurement unit, the signal processing unit, and the temperature compensation unit. The sample container is arranged at intervals between the measurement unit and the sample container and is used to hold reference samples. This application enables non-contact conductivity measurement, avoiding the electrode corrosion and cleaning problems inherent in contact measurements.

The invention discloses a negative voltage signal generation circuit and FTTR equipment, and the circuit comprises a switching circuit, an RLC circuit, a capacitor circuit, and a rectification circuit. The switching circuit is used for receiving the switching control signal and is switched on or switched off according to the switching control signal; the RLC circuit and the switching circuit are connected in series between the power supply end and the grounding end, and the RLC circuit is used for storing energy according to a positive voltage power supply signal provided by the power supply end when the switching circuit is switched on; when the switching circuit is switched off, a first electric signal is output; the capacitance circuit is connected with the RLC circuit and the switching circuit and is used for storing energy according to the first electric signal when the switching circuit is disconnected; when the switching circuit is switched on, a second electric signal is output; the rectification circuit is connected with the capacitance circuit and the signal output end and used for generating a negative voltage signal according to the second electric signal. According to the technical scheme, through cooperative work of the switch circuit, the RLC circuit and the capacitor circuit, efficient transmission and conversion of energy are achieved by using a charge pump and a switch modulation principle.

The present application relates to a kind of piezoelectric negative stiffness collaborative vibration-absorbing strut for helicopter rotor dynamic load, including upper strut and lower strut, and the vibration-absorbing component for vibration isolation between upper strut and lower strut;The vibration-absorbing component includes auxiliary ring for bearing static load, lever spring and disc spring for realizing providing negative stiffness, adjustable precompression are equipped in the auxiliary ring, mass for absorbing and dissipating vibration energy is equipped below the disc spring; Lever spring side is contacted with piezoelectric ceramic stack, piezoelectric ceramic stack connects multiple mode external circuit module, forms multiple mode piezoelectric shunt damping effect, while controlling multiple mode component of system;When vibration is larger, store electric energy, when vibration is smaller, switch to multiple mode RLC circuit dissipating mode, convert mechanical vibration energy into electric energy and consume by circuit.The present application couples negative stiffness dynamic low-frequency broadband vibration-absorbing and piezoelectric shunt multiple mode suppression, realizes the effect of high-efficiency vibration isolation.

The invention discloses a rail train equivalent circuit modeling method and system, and relates to the technical field of modeling, and the method comprises the following steps: combining equivalent circuits of a carriage and a connector with equivalent circuits of a steel rail below the carriage and a steel rail below the connector to obtain an equivalent circuit of a rail train; respectively solving the values of each impedance under different frequencies in the equivalent circuit corresponding to the compartment, the connector and the steel rail below the compartment through the plurality of impedance frequency responses to obtain the frequency response of each impedance in the equivalent circuit of the rail train; and fitting the frequency response of each impedance in the equivalent circuit of the rail train through a vector matching method, and representing the fitting result by using an RLC (Radio Link Control) circuit to obtain the equivalent circuit model of the rail train. The impedance relation between the train and the steel rail under different frequencies can be reflected, and the current path and magnitude after large current is injected into the steel rail can be analyzed conveniently.

A Quantum Field Noise Source and Secure Information Transfer system for realizing a true random signal generator, without the need for a decipher key. Electrostatically-actuated microelectromechanical beams are disposed above and across a slotline to create parallel-plate cavities. The relationship between the beam-to-slotline distance (d1) and the beam-to-electrode distance (d2) is d1<d2 / 3. The beams have a mechanical resonance frequency, ωc and are driven by a sinusoidal voltage waveform of peak amplitude Vrf and frequency Ωrf, whose DC level is set to a voltage VCntrl and is applied to the beams through a parallel RLC circuit of resonance frequency Ω0. An input signal is applied to the slotline that propagates down the slotline and is influenced by the beams. The random vibrations modulate the signal across the slotline to create white noise that is decipherable by a copy apparatus with the same layout, frequencies, beam sizes, and materials.

This invention discloses a high-voltage, high-power pulse power supply, comprising a full-bridge DC / DC converter, a second-order RLC circuit, and a pulse modulation circuit. The full-bridge DC / DC converter includes a first step-up transformer with a turns ratio of n, switching transistors S1, S2, S3, and S4, diodes D1, D2, D3, and D4, an inductor L, and a capacitor C. The second-order RLC circuit includes a resonant resistor Rr, a resonant inductor Lr, a resonant capacitor Cr, a switching transistor, and a diode D5. The pulse modulation circuit includes a second step-up transformer with a turns ratio of N1:N2, a core reset circuit composed of winding Lw and diode D7, switching transistors Q1 and Q2, a diode D6, and a pulse load Rpulse. This invention achieves high efficiency, stability, high precision, and high dynamic response in the pulse power supply system without affecting other operating performance, offering flexible adjustment and strong practicality.

The present application provides a control parameter identification method for a new energy generator set based on finite oscillation data, comprising obtaining n sets of actual subsynchronous / supersynchronous oscillation measurement data, extracting key features of each oscillation mode; establishing an equivalent RLC circuit of a new energy generator set grid-connected system, calculating the impedance value of the new energy generator set at n oscillation frequencies; establishing a theoretical impedance model of the new energy generator set, and respectively dividing the n oscillation frequencies f os Substituting the impedance of the new energy generator set with the main circuit parameters into the equations, we obtain n impedance expressions for the new energy generator set containing the control parameters to be identified. We perform a participation analysis based on the dominant oscillation mode to determine the number m of control parameters to be identified. We then use the impedances calculated based on the equivalent RLC circuit and the theoretical impedance model to construct a set of n simultaneous equations. By comparing the number n of equations with the number m of control parameters to be identified, we solve for the control parameters to be identified. This application uses finite oscillation measurement data to accurately identify the control parameters of new energy generator sets, offering ease of operation and high practicality.

The present application relates to the technical field of three-dimensional integrated circuit protection in aerospace radiation environment, and particularly relates to a method and system for simulating and modeling a microsystem interconnection module based on a through silicon via under proton irradiation. The method comprises: constructing a three-dimensional finite element model containing a through silicon via, a redistribution layer and a micro-bump, adjusting material parameters to extract scattering parameters, and establishing a correlation model between material characteristics and scattering parameters; constructing an equivalent RLC circuit in an ADS environment and establishing a corresponding relationship between the equivalent RLC circuit and the scattering parameters; combining a proton irradiation experiment to obtain scattering parameters under different radiation fluences, and further establishing a correlation model between the radiation fluence and the RLC circuit parameters. The present application combines simulation and experimental methods to achieve precise modeling between the radiation dose, the circuit parameters and the scattering characteristics, and provides support for the electrical performance prediction and protection design of three-dimensional microsystems in complex radiation environments.

The invention discloses a method for generating circuit topology based on a transfer function, relates to the technical field of circuit design, and solves the technical problem that it is difficult to combine an artificial intelligence method in circuit design to improve the efficiency and reliability of analog circuit design. The method comprises the following steps: based on a graph theory, establishing a connected graph G under a given RLC circuit structure and element parameters; deriving the relationship between the transfer function and the impedance or admittance of the network nodes of the connected graph G based on the RLC circuit; searching and calculating a tree and a secondary tree required by the transfer function, and calculating to obtain a final expression of the transfer function; analyzing the order and the structure of the transfer function, and combining specification constraints and design specifications of circuit design to obtain a circuit design rule; and searching topology and parameters of the RLC circuit through genetic programming to obtain an optimal topological structure and an optimal element admittance value. According to the method, automatic search of genetic programming is guided by analyzing the hard constraint rule set, and the efficiency and reliability of circuit comprehensive design are remarkably improved.

The application relates to a non-contact conductivity measuring device which comprises an RLC circuit formed by series connection of resistance, capacitance and inductance, a signal generator, an oscilloscope and a calculation module; the inductance is formed by a solenoid and a conductor rod arranged in the center of the solenoid; the signal generator serves as an input voltage source of the RLC circuit; the oscilloscope is used for monitoring voltage signals at both ends of the capacitance and at both ends of the input voltage source; the calculation module is used for obtaining a resonance frequency of the RLC circuit according to a ratio of the voltage signals at both ends of the capacitance and at both ends of the input voltage source; and the calculation module is also used for calculating the conductivity of a conductor rod to be measured according to an outer radius of the conductor rod to be measured, an outer radius of the solenoid, a length of the solenoid, a tightly-wound turn number of the solenoid, a capacitance value of the capacitance and the resonance frequency. It can be understood that the technical scheme shown in the application can non-contact measure the conductivity of the conductor rod, and the test accuracy is high.

The invention discloses an AC / DC power transmission line broadband equivalent analysis modeling method and system, and belongs to the technical field of power system AC / DC power transmission, and the method comprises the steps: obtaining the self-impedance and mutual impedance frequency change parameters of each phase based on a phase domain frequency change model, and converting the self-impedance and mutual impedance into differential mode impedance and common mode impedance; vector fitting is carried out on the impedance data to construct an RL branch parameter solving equation, the cascade number is determined, and an RLC circuit equivalent model corresponding to differential mode impedance and common mode impedance is obtained; a topological form of a differential mode RLC equivalent circuit corresponding to differential mode impedance and a compensation current source is adopted to construct a power transmission line equivalent circuit considering mutual inductance. According to the long-distance AC / DC submarine cable RLC equivalent modeling method, an AC / DC cable port voltage and current relation considering mutual inductance characteristics is deduced based on phase-mode transformation, a cable mutual inductance equivalent circuit based on a differential / common mode RLC circuit and a compensation current source is constructed, and the long-distance AC / DC submarine cable RLC equivalent modeling method capable of accurately reflecting frequency change, time delay, distribution characteristics and mutual inductance effects is provided.

Medical diagnostic devices and related methods of use are described in which one or multiple coils in a sensor, each coil connected with an RLC circuit and frequency counter, are held against a patient's head at predetermined cranial locations. Frequencies of the RLC circuit are measured and compared against those taken from known, control heads, to determine whether there is a medical problem and what type of problem. In some instances, too high of frequencies can reveal pooled blood in the head, a sign of hemorrhagic stroke, while too low of frequencies imply lack of blood supply, a sign of ischemic stroke. A head-mountable frame can assist a first responder in securing and guiding the coils and, along with fiducials, allow for automatic comparison of frequencies with the correct control data.

The present application provides an aerosol substrate heating parameter analysis method, a related device, and a storage medium. The aerosol analysis method is applied to an aerosol-generating system. The aerosol-generating system comprises a power supply, a radio frequency source, and a radio frequency radiator. The radio frequency radiator is configured to serve as a container for accommodating an aerosol substrate and as a radiating element for generating a heating electric field. The method comprises: equivalently modeling the aerosol-generating system in an unloaded state as a first RLC circuit; when the aerosol-generating system is in a loaded state, equivalently modeling the aerosol substrate and the radio frequency radiator as a parallel capacitor, and, on the basis of the parallel capacitor, replacing a capacitor in the first RLC circuit to form a second RLC circuit for the aerosol-generating system in the loaded state; and, on the basis of the second RLC circuit, analyzing changes in target parameters of the aerosol substrate during a heating process.

Linear time-invariant (LTI) filters are a staple of modern signal processing. LTI filters perform many operations including signal estimation, bandpass / stopband selection, encoding / decoding, modulation / demodulation, etc. Most modem LTI filters operate in the digital domain due to the flexibility of programming digital processors. However, this means that the incoming signal must be digitized. This introduces the signals to the bottlenecks and latency of digital computing, where digital electronics cannot process the increasing high data-rate and high-bandwidth data in dense spectral environments in real-time. The programmable analog LTI (PA-LTI) architecture is a hardware accelerator that performs real-time LTI operations in the analog domain and is fully programmable, enabling unprecedented acceleration of front-end PHY layer communications processing. Conventional analog LTI processors, such as RLC circuits or amplifiers, can perform only one LTI function. A PA-LTI processor can be digitally programmed to implement any arbitrary finite impulse response (FIR) LTI operation in the analog domain.

This invention discloses a method and system for modeling the equivalent circuit of a rail train, relating to the field of modeling technology. The method includes the following steps: combining the equivalent circuits of the carriage and connector, as well as the equivalent circuits of the rails below the carriage and connector, to obtain the equivalent circuit of the rail train; solving for the values ​​of each impedance at different frequencies in the corresponding equivalent circuits of the carriage, connector, and rails below the carriage using multiple impedance frequency responses, to obtain the frequency response of each impedance in the equivalent circuit of the rail train; fitting the frequency response of each impedance in the equivalent circuit of the rail train using the vector matching method, and representing the fitting result using an RLC circuit to obtain the equivalent circuit model of the rail train. This invention constructs an equivalent circuit model of the train and rails using the impedance frequency responses of the train and rails, which can reflect the impedance relationship between the train and rails at different frequencies, facilitating the analysis of the current path and magnitude after a large current is injected into the rails.

The invention provides an energy consumption optimization method and system for a plastic crusher, and relates to the technical field of energy consumption optimization, and the method comprises the steps: obtaining the working condition data of a target rotating shaft; enabling the target rotating shaft to be equivalent to a series RLC circuit, and building a complex impedance tensor for describing the working state of the target rotating shaft in combination with the working condition data; in combination with the complex impedance tensor, calculating a dissipation functional for quantifying the energy loss degree of the plastic crusher; based on the Cauchy Riemann condition, verifying whether the complex impedance tensors corresponding to the first rotating shaft and the second rotating shaft meet the complex plane crossing analytic property or not, if yes, generating a rotation angular velocity adjusting quantity, and otherwise, determining a target complex impedance tensor; respectively generating target complex impedance tensors of the first rotating shaft and the second rotating shaft in combination with an impedance matching equation; taking minimization of the dissipation functional as a target, and based on the obtained tensor, generating rotation angular velocity adjusting variables of the first rotating shaft and the second rotating shaft through conformal mapping transformation; and the plastic crusher is adjusted according to the rotating angular speed adjusting quantity, and energy consumption optimization of the plastic crusher is achieved.

This invention relates to the field of optimal control methods and devices for RLC circuits, and particularly to a steady-state control method and device for RLC series circuits based on improved ADP, comprising the following steps: S1, modeling and characterizing the RLC series circuit control system, including constructing the system state equation, giving initial state conditions and control objectives, and designing performance index functions; S2, setting core parameters, including artificial neural network parameters and iterative control parameters; S3, constructing an initial admissible control law, obtaining an initial admissible control law before formally entering strategy iteration, including selecting an initial performance index function, selecting an initial point set, initializing a BP neural network, and screening the initial admissible control law; S4, strategy iteration; S5, outputting the optimal control law. This invention has the following beneficial effects: improving the algorithm's anti-interference ability, reducing computational overhead and state space dependence, and adapting to the needs of practical scenarios where the initial state of the RLC series circuit is only within a small range but cannot be accurately known.

The utility model discloses a kind of ore carrier full-bridge inverter arc welding power supply transformer, comprising: power supply system, electronic power system, given feedback system and electronic control system;Electronic power system includes full-bridge inverter circuit, output rectifier and RLC circuit;Full-bridge inverter circuit includes four switching modules, first magnetic core inductance, direct-current blocking capacitor and transformer;The output end of any two switching modules is connected with the one end of magnetic core inductance and the one end of primary side of intermediate-frequency transformer respectively;The input end of remaining two switching modules is connected with the one end of magnetic core inductance and the one end of primary side of transformer respectively;The other end of first magnetic core inductance is connected with the one end of direct-current blocking capacitor, the other end of direct-current blocking capacitor is connected with the other end of primary side of intermediate-frequency transformer;Intermediate-frequency transformer secondary side is connected with the input end of output rectifier;The utility model avoids the problem that transformer saturation, switching tube overload caused by using high-power power supply transformer in shipbuilding process.

The invention relates to a series compensation circuit real-time voltage calculation method for time domain protection, and belongs to the technical field of power system relay protection. The initial voltage of the series capacitor is calculated through the Ohm's law and an integral formula by using steady-state current data before a fault, and calculation errors caused by protection starting delay are avoided; in combination with the nonlinear characteristic of a metal oxide varistor (MOV), the capacitor voltage is subjected to amplitude limiting processing, that is, when the calculated voltage exceeds the MOV knee point voltage VmovKnee, the forced clamping is + / -VmovKnee, and the actual working state of the capacitor during the fault period is truly reflected; a six-sequence voltage differential equation is established based on an RLC circuit model, an arrival point voltage from a protection installation position to a fault point is directly calculated, a fault is judged through an increment voltage, and a protection action is triggered when the increment voltage exceeds a threshold value. According to the method, capacitor voltage calculation can be achieved within 10 ms after a fault occurs, the error is smaller than 5%, a reliable voltage reference is provided for time domain protection, and the safety and quickness of SC line protection are remarkably improved.

An in-cell touch display device is presented herein that features an increased accuracy of touch sensitivity and touch recognition. The in-cell touch display device includes a display panel including a transistor formation layer with a driving transistor, a light emitting element layer on the transistor formation layer that includes a light emitting element, and a plurality of touch electrodes in the transistor formation layer or the light emitting element that are driven during a display period and a touch period in a time-division manner, a touch driving circuit for supplying a touch driving voltage to a touch electrode, and a power modulation circuit including a first RLC circuit and a second RLC circuit each including a resistor, an inductor, and a capacitor connected to a corresponding one of a high potential power line that supplies the driving transistor and a low potential power line that supplies a cathode electrode.

The invention relates to a modeling analysis method for a low-frequency dynamic characteristic equivalent circuit of a flexible direct-current power transmission system, which comprises the following steps of: deducing a basic transfer function between active power and a d-axis alternating current component under the influence of factors such as outer loop alternating-current voltage control and a phase-locked loop, and expanding the basic transfer function into a multi-branch transfer function model; establishing a multi-branch equivalent circuit model connected to a weak network direct-current voltage control unit after model simplification and equivalence by combining a direct-current voltage control dynamic state; based on equivalent physical circuit parameters such as equivalent resistance and equivalent inductance of the corresponding equivalent RL circuit branch, the influence degrees of multiple control links and interaction thereof, power grid strength and the like are quantitatively evaluated; a whole-system direct current side equivalent RLC circuit model is obtained by combining the dynamic states of a direct current voltage control unit and a constant power control unit, so that the low-frequency dynamic characteristic mechanism of the flexible direct current power transmission system can be clearly and intuitively seen from the perspective of an equivalent circuit, and the impedance analysis of the system can be carried out by establishing a total parallel impedance expression.

The application discloses a method for generating a circuit topology based on a transfer function, and relates to the technical field of circuit design, and solves the technical problem that it is difficult to combine artificial intelligence methods to improve the efficiency and reliability of analog circuit design in circuit design. The method comprises the following steps: based on graph theory, a connected graph G is established under the structure and element parameters of a given RLC circuit; the relationship between the transfer function and the impedance or admittance of the network nodes of the connected graph G is derived based on the RLC circuit; a tree and a secondary tree required for searching and calculating the transfer function are searched and calculated to obtain the final expression of the transfer function; the order and structure of the transfer function are analyzed, and circuit design rules are obtained in combination with specification constraints and design specifications of the circuit design; and the topology and parameters of the RLC circuit are searched through genetic programming to obtain the optimal topology structure and the optimal element admittance value. The application significantly improves the efficiency and reliability of circuit synthesis design by analyzing a set of hard constraint rules to guide the automatic search of genetic programming.

Medical diagnostic devices and related methods of use are described in which one or multiple coils in a sensor, each coil connected with an RLC circuit and frequency counter, are held against a patient's head at predetermined cranial locations. Frequencies of the RLC circuit are measured and compared against those taken from known, control heads, to determine whether there is a medical problem and what type of problem. In some instances, too high of frequencies can reveal pooled blood in the head, a sign of hemorrhagic stroke, while too low of frequencies imply lack of blood supply, a sign of ischemic stroke. A head-mountable frame can assist a first responder in securing and guiding the coils and, along with fiducials, allow for automatic comparison of frequencies with the correct control data.

Systems, methods, and apparatuses include an alternating current (AC) contactor comprising a contactor coil, the AC contactor configured to selectively connect a power source to a motor, a controller power transformer (CPT) electrically connected to the contactor coil by a CPT switch, a resistor-inductor-capacitor (RLC) circuit electrically connected to the contactor coil by an RLC circuit switch, a voltage monitor electrically connected to the contactor coil to sense voltage across the contactor coil, and a switch controller to active the RLC circuit switch to selectively connect the RLC circuit to the contactor coil during a low-voltage event determined by the switch controller from voltage across the contactor coil sensed by the voltage monitor. The RLC circuit can discharge stored electrical energy to power the contactor. A second RLC circuit can be included in the apparatus and controllably discharged to extend the low-voltage ride-through.