SU901956A1 - Device for measuring losses in magnetic core - Google Patents

Description

(54) FIT FOR MEASURING LOSSES IN MAGNETIC

I

The invention relates to an electric and {magnetic measurement and may be used to measure the magnetic characteristics of the cores of magnetic elements.

A device is known for testing the magnetic characteristics of the cores, consisting of two V-shaped cores with a gap, in which a coil with magnetic flux compensation is located and a sample is placed that absorbs a part of the magnetic flux and induces a coil in the coil. with the compensation of the magnetic flux, when the core under study is inserted, the losses in the core t are calculated.

The drawbacks of the device are the low accuracy of measurements and limitations on the shape of the core under study, which is explained by the use of a flute-compensated cutter having a measurement error.

The closest to the proposed technical essence and the achieved effect is the device representing the COMPETITOR

the battle bridge, the two arms of which are formed by a half-bridge with a common anode, and the other two plugs are formed by a resistive shunt switched on According to a differential circuit with an artificial middle point. In the shoulders of the diode half-bridge to the cathodes of the bottom} of the southeastern electromotive force sources are included in series and counter. Investigated core with magnetizing winding (included in the diagonal of the bridge between the common anode and the artificial medium point of the differential uijTrra. A voltmeter is connected parallel to the resistive shunt parallel to any shoulder containing a diode and EMF source, a pulsed current source is included. The winding magnetized current through the odo resistor resistance shunt, and the reverse current flows through the second resistance. Thus, the voltmeter registers the differential voltage 1 shunt loss gfoportsionalnoe m at peremagiichivashsh core 2.

Claims (2)

The disadvantage of this device is the low measurement measurement due to the presence in the circuit of two sources of electromotive force and two shunt resistances, as well as a pulsed current source. The purpose of the invention is to improve the measurement accuracy. This goal is achieved in that a device for measuring losses in a magnetic core containing a magnetizing winding, a diode half bridge with a common anode, and a series-connected DC current source and a voltmeter with a resistive shunt are inserted, forming a diode with a common cathode. the first diode capacitor of the bridge rectifier, and four controllable diodes of the bridge rectifier, controlled by a diode, with the input of the latter, connected to the DC generator and voltmeter, and the output to the magnetized winding . FIG. 1 shows the electrical scheme of the proposed device; in fig. 2 - time diagrams of currents, ususustriruyuschy his work. The device contains a winding 1 of magnetizing vanes with a core 2 connected to the output of a bridge terminal on diodes 3-6 whose stroke is connected to a voltmeter 7 with a resistive shunt 8 and a generator 9 of a constant current, and parallel to the diodes 3-6 the corresponding controlled keys are turned on 10-13. The device works as follows. The controllable keys 10-13 are turned on and off in pairs and alternately, for example, the keys 10 and 13 are switched on first, the time t ", then after the time Tt, counted from the moment the control keys 10 and 13 are turned on, the control keys And 12 also turn on at time t (Fig. 26). The time t of the enabled state of the controllable keys can be set to values within 0. t T, i.e. within the first halfpertode of the magnetizing current in the coil, “it thus provides the required change in the shape of the magnetizing current. When the controlled keys 10 and 13 are turned on, the magnetizing current from the generator 9 flows through the control key 10 (Fig. 2a), the magnetizing winding 1, the control key 13 (Fig. 2a), the resistive shunt 8 (Fig. 26), the resistive current The shunt 8 ig is equal in this case to the magnetizing current 1c of the winding 1 of magnetization and to the current of the controlled keys 10 and 13. After a time t about 0, the controlled keys 10 and 13 are turned on. Under the action of self-induced EMF, the reverse current flows through the magnetizing winding 1 (Fig. 2d), diode 5 (Fig. 2c), generator 9 (Fig. 2a), resistive shunt 8 4 (Fig. 2e) diode 4 (Fig. 2c) . The current of the resistive shunt 8 ig is equal to the reverse current of the diodes 4 and 5 and the current of the magnetizing winding 1 i, and in the time interval T-tj, the current c has the opposite direction. In the second half-cycle, the processes are repeated with the only difference that the current (Fig. 2e) of the magnetizing winding I changes direction and a magnetic bias occurs between core 2 (Fig. 2d). Thus, a current flowing through the resistive shunt 8 is equal to the difference between the magnetizing and reverse currents of the magnetizing winding 1, which makes it possible to exclude the measurement error of balancing the resistors of the differential resistive shunt during measurement, and eliminates the error from the source asymmetry. The use of a resistive shunt 8 in the form of one resistance and one generator 9 is possible due to the introduction of diodes 5 and 6 of control switches 10-13, which carry out pulsed magnetization from generator 9, which eliminates the need to use a complex special pulsed current source. According to the voltage U measured by the resistor, U, the difference current 1 is determined, therefore, the power loss JPy, in the core 2 under study, is equal to the product of the generator voltage 9 U and the difference current 1: РИ-EI and 1 - / Ns, where Rtu - resistance of the resistive shunt 8, therefore ft EU If it is necessary to measure losses in a core with a constant component of the magnetic flux, only one pair of controllable switches is switched, for example, 10 and 13. The intervals t, and the T-to control states are off keys can be1 varied up to the case t o -T. The selection of the control mode is provided by the requirements for the remagnetizing cycle of the core under study. Transistors or fully controlled thyristors can be used as controllable keys. Claims An apparatus for measuring losses in a magnet core, comprising a magnetizing winding, a diode half bridge with a common anode, and a series-connected direct current generator and a voltmeter with a resistive shunt, characterized in that, in order to improve the accuracy of the measured, a diode half-cavity with a common cathode forming a bridge rectifier with the first diode half bridge, four controllable keys shunting the diodes of the bridge, and the input of the latter connected to a DC generator and a voltmeter, and the output is to the magnetization winding. Sources of information taken into account in the examination 1.US Patent N 3940688, cl. G 01 R 33/12 ,, publ. 1976. 2. USSR author's certificate N404031, cl. G 01 R 33/12, 1978. / J / f