4 results about "Square wave" patented technology

The invention discloses a measurement circuit and method for an insulation monitoring instrument fault circuit. The measurement method comprises the steps that firstly, a low-frequency square-wave pulse signal with the positive electrode and the negative electrode symmetrical is generated inside an insulation monitoring instrument; secondly, a measurement loop is formed through high negative voltage, a full ground plane and an insulation resistor Rf-dc; thirdly, a sample voltage is generated on a sampling resistor Rm through current in the measurement loop; fourthly, the sample voltage is sent to a built-in microprocessor for acquisition, and the numerical value of the insulation resistor Rf-dc can be obtained by conducting calculation according to the redundant binary algorithm. The measurement circuit and method for the insulation monitoring instrument fault circuit have the advantages the measurement precision is high, reliability is high, safety is high, and the circuit and method are suitable for different environments.

The invention particularly relates to a method for switching a vector mode and a scalar mode in high-power motor control, which solves problems that over-current occurs easily in existing high-power motor control, the service life is reduced, and that the reliability of the whole system is poor. The method is characterized comprising the steps that a, when a motor speeds up, the modulation degree is increased to a limitation threshold value M1, and the control mode transits from the vector mode to the scalar mode; b, when the motor speeds down, the modulation mode gets into 3-frequency-division modulation from a square wave mode, then the control mode transits from scalar control to vector control; c, the modulation mode is switched firstly, the modulation degree reduces to acquire the modulation degree M3 as soon as getting into 3-frequency-division, wherein the modulation degree M3=Mmax-Mdelta-Mhyster; and d, after the modulation mode gets into 3-frequency-division, lux linkage gradually decreases to a normal threshold value Phim2, the control mode is switched from scalar control to vector control. The method provided by the invention prolongs the service life of the motor, and shortens the test period at the same time.

The invention discloses an electrochemical sensor electrode for rapidly and simultaneously detecting lead ions and cadmium ions as well as a preparation method and application of the electrochemical sensor electrode, and belongs to the technical field of electrochemical sensors. According to the invention, a bovine serum albumin-aminated graphene oxide-glutaraldehyde cross-linking material is synthesized in situ on the surface of a screen-printed carbon electrode, and a flower-like bismuth tungstate material is loaded on the surface of the electrode by a dispensing method, so that an electrode sensitive interface of the sensor is constructed; and simultaneous square wave anodic stripping voltammetry detection of trace lead and cadmium ions is realized. Compared with the prior art, the method has the advantages of high sensitivity, accurate result, simplicity in operation, easiness in carrying, recyclability and the like, and the heavy metals lead and cadmium in the water body can be rapidly and quantitatively analyzed and detected at the same time without pretreatment.