364results about "Inductance measurements" patented technology

A wearable therapeutic device to facilitate care of a subject is provided. The wearable therapeutic device can include a garment having a sensing electrode. The garment includes at least one of an inductive element and a capacitive element, and a controller identifies an inductance of the inductive element or a capacitance of the capacitive element, and determines a confidence level of information received from the sensing electrode based on the inductance or the capacitance. The wearable therapeutic device also includes an alarm module coupled with the controller and configured to provide a notification to a subject based on the confidence level.

An inductance parameter identification method of a synchronous motor and an implementation system thereof are provided. The method comprises: applying a three-phase balance high frequency voltage or current signal to the synchronous motor; sampling a feedback high frequency current or voltage of the synchronous motor; extracting positive sequence and negative sequence component amplitude of the feedback high frequency current or voltage which has the same frequency of the injecting voltage or current; and calculating to get d-axis inductance Ld and q-axis inductance Lq of the synchronous motor. Identification of the d-axis inductance and q-axis inductance of the synchronous motor can be implemented more accurately on a general inverter on the basis of non-increase of hardware cost. The method and system have the following advantages of implementing easily, not high demand for the motor feedback current sampling accuracy, and controlling easily for the frequency and amplitude of the high frequency voltage signal injected into the motor, and identifying to get the d-axis inductance and q-axis inductance of the motor directly no matter the motor shaft is in a free state, or in a hold tight stage, which do not affect accuracy of identification.

Apparatuses and methods for measuring stress or strain in a conductive material without physical contact with the material are provided. The device comprises an inductor circuit configured to induce an alternating current into the material along a first path; and a detector configured to detect a signal representative of the stress in the material along the first path when current is induced in the material.

A method of estimating inductance of a permanent magnet synchronous motor (PMSM) includes injecting a signal having a frequency differing from an operating frequency of the PMSM into the PMSM during sensorless operation, sensing magnitudes of current responses to the injected signal, and estimating an inductance value at which the magnitude of the sensed current response is minimal to be an actual inductance value of the PMSM, thereby estimating inductance used in the PMSM regardless of position estimation error of the PMSM and thus more accurately and reliably estimating inductance of the PMSM.

A compact instrument package consisting of a rotating sensor and supporting signal-processing electronics is capable of measuring two-dimensional electric-field vectors, ranging from DC to an arbitrary upper AC frequency not limited by the rotation rate, with highly improved accuracy and sensitivity when compared with previous art. In addition, contrary to previous art, the sensor can measure the electric field gradient at its location. This is achieved by the use of a combination of quadrature modulation and phase-sensitive quadrature demodulation digital signal processing in a generic rotating electric-field sensor. Ground isolated versions of the instrument can be used singly or in arrays when precise measurements of the electric fields are necessary. Either grounded or isolated versions of the instrument can operate continuously without the need for internal batteries, making it extremely attractive for a wide-range of industrial and space applications. Operational modes have been developed to distinguish the effects of ion currents and charged particles impacting the sensor from the local ambient electric field. Moreover, particular versions of the instrument can be operated in corrosive environments and conducting fluids.

A touch sensor having a touch sensitive film, a signal filter, electrical circuitry and a processing unit. The film is capable of capacitive or inductive coupling to an external object when a touch is made by the object. The signal filter is formed by the resistance of the film and the capacitive or inductive coupling to the external object, and the filter has properties affected by location of the touch and / or capacitance or inductance of the touch. The electrical circuitry is coupled to the touch sensitive film and configured to supply excitation, amplitude and wave form into the signal filter and to receive response signals from the signal filter. The processing unit is configured to detect the presence or proximity of a touch, the location of said touch, the capacitance and / or inductance of said touch by processing response signals and thereby measuring changes in the properties of the signal filter.

A system and circuit for achieving bidirectional hysteretic current mode control of a converter. The system comprises a summer that provides a constant hysteresis and has added switching noise immunity, a comparator, a lossless inductor current sense means and a converter. A circuit using the inductors internal resistance for sensing the current through an inductor in a lossless manner is described. The circuit preserves both DC and dynamic current information while incorporating the RC time constant, difference amplifier and signal amplification, all using only one amplifier. This circuit provides excellent common mode and differential noise immunity, while still having a high bandwidth and small group delay of the current signal. A method to accomplish stability of a current mode controlled converter when closing the loop to control the output voltage with very high accuracy and gain is described.

The present invention includes a detection coil (4) in a self-oscillation circuit (10) in a position detection device. The oscillation frequency of the self-oscillation circuit (10), which is configured from the coil (4) and a capacitor, is set to a high frequency band (for example, around 1 MHz or higher). A target section (3) of which the relative position with respect to the coil (4) changes in accordance with the displacement of a detection subject comprises a magnetically responsive member configured in a manner so as to change the inductance of the coil (4) in accordance with the relative position. A rectifier circuit (21) extracts the amplitude level of the oscillation output signal of the self-oscillation circuit (10) and outputs the result as position data of the detection subject. As an example, a plurality of self-oscillation circuits (10a, 10b) are provided. As a separate example, a single self-oscillation circuit (10) forms a plurality of series circuits by, for every pair of a plurality of coil pairs, connecting in series the two coils (4a, 4b) configuring the coil pair, and includes the result of connecting the series circuits in parallel as an inductor element for self-oscillation.

A device for detecting a user's intention to lock or unlock a motor vehicle door, integrated into a handle (10) and consisting of a casing (B′) includes a first part (52), elastically deformable along a predetermined axis (Y-Y′), with an area (50) of contact with the handle, a printed circuit (80), a voltage source (Vcc), and a contact detection element (100) including:a non-magnetic metal target (40) which moves along the predetermined axis,a coil (20), and a capacitance (C1), forming an oscillating circuit,elements (M1) for adjusting the frequency of the circuit,a prestressed compressible element (30), located between the target and the coil,elements (51) for transmitting a movement of the first part to the target,elements (M2) for measuring an inductance (L) of the coil,elements (M3) for comparison between the measured inductance and a predetermined threshold value of inductance (Ls),and control elements (60′).

A method and an arrangement of determining inductances of a synchronous reluctance machine are provided. The method includes supplying a voltage pulse in the quadrature-axis or direct-axis direction of rotor, sampling currents generated by the supplied voltage pulse, and calculating values of flux at the sampling instants from the value of the supplied voltage pulse, the sampled current values and a value of the stator resistance. The method also includes calculating synchronous inductance of the machine by dividing the calculated flux values by the corresponding sampled currents, and / or calculating transient inductance of the machine as a derivative of the flux with respect to current, and storing the calculated values as a function of current.

A power transmission apparatus oscillates alternating current power at a first frequency (f1) which is lower than a resonant frequency (fr) of the second resonator and at a second frequency (f2) which is higher than the resonant frequency (fr). The power transmission apparatus measures an inductance value Lin (f1) and an inductance value Lin (f2). The inductance value Lin (f1) is measured when the oscillation circuit oscillates alternating current power at the first frequency (f1), and the inductance value Lin (f2) is measured when the oscillation circuit oscillates alternating current power at the second frequency (f2). The power transmission apparatus calculates a coupling coefficient k by using an expression represented by k 2 = 1-Lin(f2) / Lin(f1), to detect relative position of the second resonator to the first resonator on the basis of the coupling coefficient k.

Apparatuses and methods for measuring stress or strain in a conductive material without physical contact with the material are provided. The device comprises an inductor circuit configured to induce an alternating current into the material along a first path; and a detector configured to detect a signal representative of the stress in the material along the first path when current is induced in the material.

An integrated circuit for compensating for parasitic capacitance in a capacitive measuring apparatus wherein a capacitance measurement is done by repeatedly transferring charge from a capacitor to be measured to a reference capacitor.

The invention discloses a test method and device for nonlinear parameters of a motor, and the method comprises the following steps of exciting vibration of the motor by using an excitation signal, performing synchronous information acquisition on the motor in a vibrating state to obtain a voltage measured value and a current measured value, acquiring a linear parameter initial value and a nonlinear parameter initial value of the motor, calculating a linear parameter target value of the motor according to the voltage measured value, the current measured value and the linear parameter initial value, and calculating a nonlinear parameter target value of the motor by adaptive filtering according to the voltage measured value, the current measured value, the linear parameter target value and the nonlinear parameter initial value. By measuring the nonlinear parameters of the motor, accurate control of the motor vibration is realized by using a nonlinear model to improve the control accuracyof the motor, thereby improving motor performance.

A system and technique for measuring the mutual inductance in a switched reluctance machine (SRM). In a first example embodiment of the technique, a voltage pulse is applied to primary coil when the machine is stationery. By measuring current in the primary coil and measuring induced voltages in adjacent open circuited coils mutual inductance may be determined. In another example embodiment, a voltage pulse is applied to the primary coil when the machine is stationery. The secondary coil is allowed to freewheel current through the phase. By measuring time taken by the primary phase to reach a preset value, the mutual inductance for the known position of a rotor can be determined.

An improved sensor apparatus for developing a signal related to an inductive sensor in a resonant circuit are disclosed. This improvement is realized by adding a known capacitance to the resonant circuit and comparing the resulting natural resonance frequency to the frequency without the known capacitance. In this way a measure of the resonant capacitance is developed to correct the sensor signal for the effect of any changes in that capacitance. One disclosed embodiment adds an electronically variable capacitance which is adjusted to yield a constant capacitance that produces a sensor signal insensitive to variations in the resonant circuit capacitance. The resonant capacitance measurement may also provide an indication of another sensor state, such as temperature or pressure, which may be used to further correct for temperature or pressure sensitivities in the sensor signal. The invention is extended by juxtaposing the inductance for capacitance in the sensor resonant circuit.

A method of estimating stator resistance of an induction motor is provided. The method includes applying voltage pulses through two phase paths of the motor for a plurality of electrical cycles to inject current in the motor, wherein the voltage pulses are applied until rotor flux of the motor is substantially stabilized and measuring stator voltage and stator current in response to the applied voltage pulses for each of the plurality of electrical cycles. The method also includes calculating the stator resistance based upon the measured stator voltages and the stator currents.

A key switch assembly is provided wherein a spacer is used to isolate the key switch sensing circuit from the front panel of the device. A button assembly is provided to translate a deflection of the front panel of the device to a target coupled to a sensor of the sensing circuit.

The invention provides a rapid multifunctional electronic component temperature characteristic measuring device and instrument, and a testing cavity. Temperature characteristic curves of parameters such as capacitance, inductance, resistance, dielectric coefficients, dielectric loss, voltage-current curves and spontaneous polarization of a plurality of electronic components and material samples can be measured. The rapid multifunctional electronic component temperature characteristic measuring device and instrument and the testing cavity is small in size, light in weight, high in speed, high in automatic degree, multi-functional, high in precision and low in cost. The device, instrument and the testing cavity can be applied by an enterprise to rapidly detect temperature characteristics of electronic components, can also be used by scientific research laboratories to research temperature characteristics of specific parameters of the devices and the material samples, and can further be used in the aspect such as experiment demonstration and class teaching.

A system and method are provided to enable the indication positions of respective indicators (e.g., fingers) to be detected (multiple-point detection) and also to enable detection of the users of the indicators (user detection). Signal generators for generating different signals for respective users are provided, and the signals from the signal generators are supplied to a sensor section through indicators. In a multi-touch and multi-user detecting device 1, a transmitting section 200 supplies determined signals to respective transmitting conductors 11Y. Respective receiving conductors 12X receive the signals from the transmitting conductors 11Y and also the signals from the signal generators of the users. Based on these signals, a user-and-position identifying circuit 33A and a position detecting circuit 34A in a receiving section 300A function to detect indication positions indicated by the respective indicators as well as the users using the indicators.

An integrated circuit for compensating for parasitic capacitance in a capacitive measuring apparatus wherein a capacitance measurement is done by repeatedly transferring charge from a capacitor to be measured to a reference capacitor.

An electric vehicle battery arrangement includes a current sensor. The current sensor has a core and a magnetic field detector. An N-turn coil is wrapped around the core. A controller is configured to adjust an output of the detector indicative of current according to a comparison between a magnetic field caused by a given current in the coil as detected by the detector and a magnetic field expected to be caused by the given current in the coil.

In one embodiment, a sensor arrangement for the contactless sensing of angles of rotation on a rotating part includes a disk-shaped target, a coil arrangement, and an evaluation and control unit. The disc-shaped target is coupled to the rotating part and includes at least two metal surfaces that influence the inductances in the flat detection coils due to eddy current effects as a function of the degree of overlap. The disc-shaped target can generate at least one piece of information for ascertaining the instantaneous angle of rotation of the rotating part, in connection with the coil arrangement. The coil arrangement has has three flat detection coils uniformly distributed on the circumference of a circle. The evaluation and control unit can generate essentially sinusoidal evaluation signals which represent the changes in inductance of the detection coils and can evaluate them for calculating the angle of rotation.

Provided are a land settlement measuring apparatus and a land settlement measuring system. The land settlement measuring apparatus includes a magnetic field detection unit, a microprocessor, and a containing unit. The magnetic field detection unit includes a plurality of magnetic field detection sensors that are separated from each other in a predetermined interval. The microprocessor calculates a differential settlement amount based on a magnetic field detection signal transmitted from the magnetic field detection unit, in the case where a change in the magnetic field is detected by the sensor. The containing unit contains the magnetic field detection unit and the microprocessor. The land settlement measuring system includes a magnetic field generation unit, a land settlement measuring apparatus, and a data logger. The magnetic field generation unit is disposed at a predetermined position of a ground to be adjacent to a hole which is perforated down to an unmovable layer. The land settlement measuring apparatus passes through the hole so that the one end thereof is fixed to the unmovable layer, the land settlement measuring apparatus measuring a differential settlement amount according to a change in the position of the magnetic field generation unit. The data logger stores a result of the measurement transmitted from the land settlement measuring apparatus. According to the configuration, it is possible to collectively measure a differential settlement amount of a surface of a settling layer and a differential settlement amount of the settling layer in one system and to obtain a more accurate value of the measurement.

A method for detecting the presence of a receiver in an inductively coupled power transfer system having a transmitter and receiver. The method includes switching on a transmitter converter at a first frequency, measuring the inrush current and determining whether there is a receiver present. In another method, the inrush current is measured for a range of transmitter frequencies, and the variation in current is used to determine where there is a receiver present. In another method, the inrush current is measured when there is a change in voltage in the transmitter, and the variation in current is used to determine where there is a receiver present. In another method, the current supplied to the transmitter converter is measured over two transmitter frequencies, and the variation in current is used to determine where there is a receiver present. In another method, the current supplied to the transmitter converter is measured over two transmitter voltages, and the variation in current is used to determine where there is a receiver present.

The invention discloses a method for measuring the inductance in the deep saturation state of a transformer. The method is used for solving the technical problem that in the prior art, no method is provided for simulating the running state of a transformer in a deep saturation state. According to the invention, the excitation surge current and the secondary side voltage of the transformer when thetransformer is in no-load and switched-on state are measured. Through the numerical integration and the calculation, the excitation curve of the transformer can be obtained. Meanwhile, the range of the excitation surge current is large, and the obtained excitation curve contains excitation characteristics in the deep saturation state. Therefore, the inductance of the transformer in the deep saturation state can be obtained by performing linear fitting on the obtained excitation curve. The operation state of the transformer in the deep saturation state can be studied by the engineering operation and maintenance personnel.