34results about How to "Phase detection error is small" patented technology

The invention discloses a phase-locked loop applicable to power grid voltage unbalance and distortion states, and belongs to the related technical fields of power grid voltage phase signal detection and power grid load harmonic current extraction. The phase-locked loop provided by the invention aims to solve the problem as follows: the conventional synchronous rotating reference frame based three-phase digital phase-locked loop cannot accurately detect the phase value of the three-phase voltage fundamental wave positive-sequence component under power grid voltage unbalance and distortion states; consequently, the precision of a related harmonic current extraction algorithm is lowered, and the compensation effect of a harmonic compensation apparatus is weakened. The phase-locked loop provided by the invention improves the conventional three-phase digital phase-locked loop, and a repetition controller is introduced; the repetition controller is connected with a proportional integral controller in parallel to form a new controller, so that the excellent steady-state performance of the repetition controller is combined with the excellent dynamic performance of the proportional integral controller; and therefore, the phase-locked loop has the advantages of high dynamic response, high detection precision and the like. The phase-locked loop is mainly applied to voltage phase detection under power grid voltage unbalance and distortion states.

The invention discloses a fiber sensor based on Michelson interference and belongs to the technical field of the fiber sensor. A main structure of the fiber sensor comprises a pump source (1), a firstoptical coupler (2), an optical wavelength division multiplexer (3) and the like. According to the fiber sensor, a sinusoidal signal is taken as a modulation signal and high frequency interference isnot generated. The fiber sensor is characterized by relatively reliable working, high sensing precision and wide application range.

The invention relates to a temperature sensing system for mine safety monitoring and belongs to the technical field of optical fiber sensors. Its main structure includes a pumping source (1), a first optical coupler (2), an optical wavelength division multiplexer (3) and the like. The invention uses a sinusoidal signal as a modulation signal, does not generate high-frequency interference, and has the characteristics of more reliable operation and high sensing precision.

The invention provides a micro stress sensor based on phase comparison, and belongs to the technical field of optical fiber sensors. The main structure of the micro stress sensor comprises a pumping source (1), an optical wavelength division multiplexer (2), an erbium doped optical fiber (3), and the like. The micro stress sensor provided by the invention uses a sinusoidal signal as a modulation signal, thereby generating no high frequency interference, and having the characteristics of more reliable work, high sensing precision, wide application range, etc.

The invention discloses a multipurpose fiber sensor and belongs to the technical field of a fiber sensor. A main structure of the multipurpose fiber sensor comprises a pump source (1), an optical wavelength division multiplexer (2), an erbium-doped fiber (3) and the like. According to the multipurpose optical fiber sensor, a sinusoidal signal is taken as a modulation signal and high frequency interference is not generated. The multipurpose fiber sensor is characterized by relatively reliable working, high sensing precision and wide application range.

The invention discloses an optical fiber sensor based on sine wave modulation, and belongs to the technical field of optical fiber sensors. The main structure is a pump source (1), an optical wavelength division multiplexer (3), an erbium doped fiber (3) and the like. According to the optical fiber sensor based on sine wave modulation, a sinusoidal signal is used as a modulation signal, high-frequency interference is not generated, and the invention has the characteristics of being more reliable in operation, high in sensing precision, wide in application range and the like.

The invention provides a micro-stress sensor for bridge monitoring, and belongs to the technical field of optical fiber sensors. The sensor is mainly provided with a pumping source (1), an optical wavelength division multiplexer (2), and an erbium-doped optical fiber (3). The sine signal is used as a modulation signal, high-frequency interference cannot be generated, and the sensor has the advantages of being more reliable in work, and high in sensing precision.

The invention relates to a multi-point temperature sensing system composed of Bragg gratings, which belongs to the technical field of optical fiber sensors. Its main structures include a pump source (1), an optical wavelength division multiplexer (2), an erbium-doped optical fiber (3) and the like. The invention uses a sinusoidal signal as a modulation signal, does not generate high-frequency interference, and has the characteristics of more reliable operation, high sensing precision, wide application range and the like.