687 results about "Signal injection" patented technology

A solar panel system includes a plurality of the panels connected together in one or more panel strings. An embodiment includes a signal generator module connected to the photovoltaic panel strings injecting a multiple radio frequency signal onto each of the strings and a detector module analyzing a frequency response echo from the panel strings. The signal generator may include a string coupling module communicating with a controller. The detector module analyzes the echo to obtain an analog fingerprint for each panel string and determine whether the fingerprint for each panel string is within an acceptable range. The detector module initiates an alarm when one of the fingerprints is outside the acceptable range. During night time, when no current is being produced by the photovoltaic cells, a DC or AC source may be connected to the panel strings to inject a signal onto the strings for the same purpose.

A two-optical signal generator is provided for generating two optical signals, where a difference between optical frequencies or optical wavelength of the two optical signals can be adjusted. A first optical modulator modulates a single-mode optical signal generated by a first light source according to an inputted signal, and outputs a modulated optical signal including predetermined specific two optical signals having a predetermined optical frequency difference, while a second light source generates a multi-mode optical signal including predetermined two further optical signals having substantially the same wavelengths as those of the predetermined specific two optical signals of the modulated optical signal, respectively. Then an optical injection device optically injects the modulated optical signal into the second light source, and the predetermined specific two optical signals of the modulated optical signal are injection-locked into the predetermined two further optical signals of the multi-mode optical signal, so that the second light source generates an injection-locked predetermined specific two optical signals.

The invention provides a method for detecting the initial position of a magnetic pole of a rotor of a built-in permanent magnetic synchronous motor, belongs to the field of motor control, and solves the problems of over-complicated processing, easy occurrence of polarity misjudging, poor practicality and the like existing in the conventional method based on high-frequency signal injection for detecting the initial position of the rotor. The method comprises the following steps: constantly maintaining the stationary state of the rotor; injecting a rotating high-frequency voltage signal into a stator winding; detecting three-phase stator current and converting the three-phase stator current into two-phase static coordinates; acquiring an error signal capable of reflecting position information of the magnetic pole of the rotor through signal processing; adjusting the error signal by using a PI tracker so as to acquire an initial judging value of the position of the magnetic pole of the rotor; and injecting two impulse voltage vectors in opposite directions into the stator winding, comparing values of direct axis current components by detecting the three phase current and converting the rotating coordinates so as to determine the polarity of the magnetic pole, and finally acquiring the initial position angle of the magnetic pole of the rotor of the built-in permanent magnetic synchronous motor.

The invention discloses an insulation detection method based on low frequency impulse signal injection. Low frequency impulse signal injection is adopted to detect an insulating performance of a whole vehicle, and a capacitor is adopted to separate a high-voltage current from a detection circuit and separate a direct-current system of the whole vehicle from a low frequency impulse signal, so that an alternating current interference signal brought for an electrical system through high frequency signal injection is reduced, and the defects of reducing the insulating performance of the whole vehicle, incapability in locating an insulation fault point, complex structure, inaccuracy in detection when a positive pole and a negative pole are leaked simultaneously, which are caused by other detection methods, are avoided.

The present invention relates to the technical field of electrical engineering and discloses a PRBS disturbance injection-based power grid impedance online identification device. The device is mainly composed of a grid-connected inverter, a current loop controller, a sampling device and an impedance identification unit. The device is characterized in that the grid-connected inverter is connected with the current loop controller. When the grid-connected state is stable, the grid-connected inverter injects the PRBS disturbance into the power grid. During the injection process of a PRBS signal, a built-in output voltage THD is fed back to the controller, so that the THD value of the output voltage of the inverter is ensured to be smaller than 5%. The sampling device is connected with the PCC part of the power grid and is used for sampling and recording the voltage and the current at the PCC part of the power grid. The impedance identification unit is used for subjecting the sampled data of the sampling device to DFT analysis, and taking the average value of the amplitude and the average value of the phase of each harmonic component of the voltage and the current during the current sampling period. The method of the invention is high in precision, high in speed, strong in real-time property, wide in frequency range, lower in measuring cost and difficulty, and better in stability.

The invention relates to a motor control system and method without a position sensor. According to the invention, internal signals of a motor can be detected without needing the position sensor. In the motor control system without the position sensor, a high-frequency voltage signal injection unit injects a high-frequency voltage signal to a d axis in a synchronically rotating d-q coordinate system; the voltage signal is obtained by a Park inverse transformation unit; a voltage vector on a static coordinate system generates a power device pulse width signal through a space vector pulse width modulation algorithm; a three-phase current signal and a high-frequency injection signal are generated according to the power device pulse width signal; the three-phase current signal is filtered by using a band-pass filter to reserve the high-frequency injection signal; the high-frequency injection signal is subjected to Clarke transformation and Park transformation in turn to obtain current; the current is subjected to signal processing through a rotor position observer unit to obtain position and speed of a rotor. According to the invention, internal structure of a motor system is simplified, cost for the motor control system is greatly reduced, and stability of the motor is improved.

The invention relates to a system and method for determining direct current system fault branch circuits needing to be in in-series connection with alternating currents. The system comprises an on-line monitoring device, wherein the input of the on-line monitoring device is connected with the positive electrode and the negative electrode of a direct current bus and the ground; a plurality of fault locating devices are arranged in various direct current branch circuits respectively, and the on-line monitoring device is connected with each fault locating device through a communication bus. The method comprises the steps that 1) positive electrode voltage to ground U+, negative electrode voltage to ground U- and in-series connected alternating voltage Uac of the direct current bus are detected, and when the Uac is greater than a set value Uaca, the situation that a direct current system has alternating current in-series connection faults is determined; 2) when the U- is less than or equal to delta U, the situation that the alternating currents are connected to the direct current system in series through the positive electrode is determined; when the U+ is less than or equal to the delta U, the situation that the alternating currents are connected to the direct current system in series through the positive electrode is determined; 3) leak currents of all the branch circuits of the direct current system are detected and ordered, the branch circuit having the maximal leak current value is the branch circuit needing to be in in-series connection with the alternating currents. According to the system and method, an alternating current sensor does not need to be additionally arranged, and system cost is saved. Meanwhile, according to the scheme, signal injection does not exist, and therefore increase of ripples of the direct current system will not be caused, the problems that a relay mistakenly moves and a breaker mistakenly trips are solved, and reliability is higher.

A smart sensor network for power grid health monitoring includes a plurality of spaced sensors that are magnetically coupled to the power transmission line to be monitored. The sensors include a signal injection unit and a signal sensing unit. As such, one of the sensors acts to inject, via its signal injection unit, a high frequency signal through the magnetic coupling into the power transmission line, while sensors on either side of the signal injecting sensor act to block the injected signal, which is then detected by the signal sensing unit of the injecting sensor, and is used to measure the impedance of the power transmission line segment being analyzed. Based on the difference between a pre-measured impedance of the power transmission line being monitored and the actual impedance value of the power transmission line being measured by the sensor, the health of the power line can be obtained.

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.

Arrangement to determine at least one electrical feature of an electrical device includes a signal injection unit configured to inject first and second test signals into electric, a signal conversion unit configured to measure electrical qualities in the electrical circuits resulting from the test signals, and a processing device including at least two input channels configured to receive the measured electrical quantities and to determine the electrical feature based on the measured electrical quantities, a mixing unit configured to add the measurements of the first electrical quantity from the test signals and based thereon generate a first mixed signal, to add the measurements of the second electrical quantity from the test signals and based thereon generate a second mixed signal, and to supply the first and second mixed signals to first and second input channels.

A PFC circuit modulating a power line using pulse width modulation (PWM) to drive a power MOSFET and series inductor across the power line. Since many modern electronic systems include a power factor correction circuit (PFC) that already includes a series inductor and power MOSFET, a PLC is incorporated into a controller to inject a PLC transmit signal into a control loop for the PFC circuit. This can be done using either an analog PFC controller, such as the UCC28517, the UCC2819A, or a digital PFC controller such as based on a TMS32OC24xx DSP.

The invention belongs to the technical field of storage battery management and provides a storage battery online monitoring system and a monitoring method thereof, wherein the system comprises at least one storage battery monitoring terminal and a storage battery monitoring center, the storage battery monitoring terminals are arranged at corresponding monitoring points, connected with storage battery poles and used for collecting ripple voltage of storage batteries; and the storage battery monitoring center comprises a ripple signal injection module which is used for injecting ripple current to the storage batteries synchronously, and meanwhile, the storage battery monitoring center collects the ripple current on a return circuit of a storage battery group and calculates and displays the internal resistance of corresponding storage batteries according to the ripple voltage and the ripple current. According to the storage battery online monitoring system and the monitoring method thereof, as the storage battery monitoring terminals used for the ripple voltage collection of the storage batteries are distributed at various monitoring points, and the collection of the ripple current is completed independently by the storage battery monitoring center, the situation that the collection of ripple voltage and ripple current is carried out by the same monitoring module is avoided, the waste of resources is reduced, and the cost is reduced on the premise of ensuring the accuracy.

A permanent-magnet synchronous motor sensorless control method adopting square-wave injection belongs to the field of motor control. The invention aims to solve the problem that the permanent-magnet synchronous motor is applicable to low-speed sensorless control technologies and the traditional sine signal injection method demands high injection frequency and is of poor dynamic performance. First, a square-wave voltage signal is injected to a control shafting; then, the signal is processed based on excited current response under an observation shafting which lags behind the control shafting by 45 degrees to obtain a position deviation signal; and finally, the observed value of the rotor position is obtained through a Luenberger observer. The method of the invention is applicable to permanent-magnet synchronous motor sensorless control.

The invention discloses a method and a device for locating a single-phase grounding fault of a low-current grounding system. When the low-current grounding system has the single-phase grounding fault, a signal with pilot frequency different from grid frequency is injected between a fault phase and the ground, the voltage and current of the pilot frequency signal are detected at a signal injection end, an imaginary part of complex impedance of a fault loop under the frequency, namely a reactance value is calculated, and the distance between a signal injection point and a fault point can be obtained by multiplying the reactance value by a proportional constant. The signal is only needed to be injected at one end of a power grid, and the fault distance is directly measured and calculated, so that the method is simple and practicable, has high measuring accuracy, and has great significance for shortening fault removal time and improving the power supply quality of the power grid.

The invention discloses an on-line rotational inertia identification device for an alternate current permanent magnet servo system and an identification method, belongs to the technical field of servo motor control, and solves the problem that the conventional identification of rotational inertia of all motors is identification of rotational inertia of load mechanical systems in an off state so as not to adjust system control parameters according to current conditions of a system in real time. The device consists of a position controller, a speed controller, a torque controller, a motor and load unit, a photoelectric encoder, a differential unit, a sinusoidal signal generator and a rotational inertia identification unit; and the method comprises the following steps of: injecting a harmonic command with a lower amplitude value to a given position of a position loop motor during production run of a motor system; and extracting a motor position angle and torque control signal of a corresponding frequency component to realize on-line identification of the rotational inertia. The device and the method are suitable for on-line rotational inertia identification of the alternate current permanent magnet servo system.