SU974308A1 - Device for measuring external magnetic field strength and direction - Google Patents

Description

The invention relates to measurement technology and to the elements of auto; metallization of production processes and is intended, in particular, to measure the inhomogeneity of the magnetic field and to determine the presence of a magnetic field direction from local sources, for example, from permanent magnets mounted on mechanisms.

The known devices of similar purpose containing cores of magnetically soft material and windings wound on them have low sensitivity, especially when supplied with a voltage of industrial frequency of 50 Hz, are not protected from the effects of external uniform fields (Earth's magnetic field, etc.) and do not determine the direction of magnetic fields.

The present invention is free from the above disadvantages due to the implementation of the power supply unit of the device.

In the form of a Z-shaped diode circuit, one end of which is connected to one output of the excitation winding and through a capacitor, the junction point of two diodes of the Z-shaped circuit and the thyristor to another of its output, and the other end is connected to a thyristor control electrode through a resistor a resistor with a working winding terminal and simultaneously through an output thyristor with a different point of connection of two diodes of the Z-shaped circuit, and the control electrode of the output thyristor is connected to another output of the working winding.

FIG. 1 is a schematic diagram of the device; in fig. 2 is a schematic representation of transients during capacitor discharge, explaining the principle of determining the direction of a controlled magnetic field.

Claims (2)

The device consists of a flux-gate with two open cores 1. The excitation windings are wound at the end of each core. The cores 1 with the windings 2 are fastened to each other and the working windings 3 are wound on top of the ends and connected to the thyristor control circuit A, Winding 2 is connected to thyristor 5 and capacitor 6. When opening thyristor 5, capacitor 6 is discharged to windings 2. On the circuit: diode 7 - capacitor 6 - diode 8 in one half-period the capacitor 6 is charged, and on the circuit; resistor 9 thyristor 5 - diode 10 in the other half period is given an opening signal to thyristor i. The sensor operates as follows. When an alternating voltage supply IJn with a frequency of 50 Hz is applied, capacitor 6 is discharged each time into windings 2, which create magnetic flux Φ (Fig. 2), characterized by covered front and gently falling back fronts. In each loop 3, these fluxes generate EMF E and E, and the leading edges excite short pulses of large amplitude, and the back edges excite pulses of long duration but small amplitude that can be neglected, i.e. The signal is received. Polar. In the absence of an external magnetic field, these pulses are mutually compensated at the output of each of the windings 3, the voltage is absent. When the cores 1 are magnetized by an external magnetic field, their magnetic permeability changes. As a result, a difference in the EMF E – E appears in the windings 3, and its sign is determined by the direction of the external magnetic field. If the external field is homogeneous, then the cores are uniformly magnetised along their length and the differences 3flC induced in windings 3 are the same, and since windings 3 are turned on, the output signal to the thyristor 4 is zero. If the external field is non-uniform along the sensor, for example from magnet 11, the right and left ends of the cores are differently magnetically and the thyristor control circuit receives a signal proportional to the magnitude of the external magnetic field heterogeneity and, if the incoming signal is matched to the thyristor input, the latter opens and applies the operating voltage to the load 12. With reverse polarity, the thyristor k remains closed. The output signal supplied to the input of the thyristor is positive or negative (depending on the direction of the external magnetic field), a magnitude of ten volts in amplitude, but of short duration. Therefore, the main purpose of the thyristor k is an extension of the output signal and an indication of the direction of the external magnetic field. Apparatus of the Invention A device for measuring the magnitude and direction of external magnetic fields, comprising a ferrosonde with two open cores, the ends of which are wound by two respectively-connected excitation windings and working-connected working windings, a power supply unit and a recording device, characterized in that In order to improve measurement accuracy, the power supply unit of the device is made in the form of a Z-shaped circuit of diodes, one end of which is connected to one output of the field winding and through the condenser the ator, the connection point of the two Z-shaped diodes and the thyristor with its other output, and the other end through a resistor connected to the control electrode of the thyristor and through the load resistor with the output winding and simultaneously through the output thyristor with a different connection point of the two diodes Z -like circuit, and the control electrode of the output thyristor is connected to another output of the working winding.