SU957286A1 - Device for forced controlling of dc electromagnet - Google Patents

Description

one

The invention relates to automation and can be used for the effective control of DC electromagnets with reduced energy consumption, in particular, to aeronautical and space technology.

Devices of a shaped direct current electromagnet control are known, comprising a circuit of a series-connected electronic key, a feedback element, an unstabilized constant voltage source, and an electromagnet shunted by a circuit of its magnetic energy, as well as a forming circuit connected to the exciter of the field current and cyclic mode driver 1.

In such a device, the duration of the stage of forcing an electromagnet is constant, i.e. it does not depend on its parameters, which leads to excessive energy consumption in the electromagnet in the forcing stage.

Closest to the proposed technical essence and achievable result, a device for the formed control of a direct current electromagnet, containing an unstabilized source of direct voltage, an electronic key, a feedback element, an exciter current generator, a cyclic mode driver, a pulse accumulating link and an electronic switch , wherein the input of the pulse storage link is connected to the connection point of the power electronic key and the electromagnet, and the output is connected to the control electronic switch input, switching electrodes

, Q of which is connected to the set point of excitation current 2.

The disadvantage of this device is the instability of the forcing stage due to the change in the number of operating cycles of the power electronic key in this stage with the instability of the parameters of the pulsed storage link and the electronic switch. In this case, one cycle may be insufficient in time for the operation of the electromagnet (for example, in the case of significant losses of its magnetomotive force in a transient mode from capacitive and eddy currents), and a large number of cycles leads to impaired optimization (increase) in energy consumption in the electromagnet. In addition, the device is relatively complicated and requires adjustment. The purpose of the invention is to reduce energy consumption and simplify the device. This goal is achieved by the fact that a device containing leads for connecting an electromagnet winding, one of which is connected to one of the terminals for connecting an unstabilized constant voltage source, and the other to one of the power electrodes of the electronic key, the other power electrode of which is connected with one of the terminals of the feedback element, the other terminal of which is connected to another terminal for connecting an unstabilized constant voltage source, the control electrode of a power electromagnet The key is connected to the output of the cyclic mode generator, one of the inputs of which is connected to the connection point of another power electrode of the power electronic key and one output of the feedback element, the other input of the driver is connected to the output of the field current setting device, the control input of which is connected to the electronic switch, A counting element is introduced, the counting input of which is connected to the output of the cyclic mode generator, the reset input is connected to the device input, and the output is connected to the control input this switch The drawing shows the proposed device. The device contains an excitation winding of electromagnet 1, power electronic switch 2, feedback element 3, diode 4, resistors 5-8, electronic switch 9, comparator 10, capacitor 11, resistors 12 and 13, counting element 14, electronic switch 15, unstabilized constant voltage source E, reference voltage source Ерп, input source UgxConnectedly connected unstabilized constant voltage source E, excitation winding of electromagnet 1, power electronic switch 2, for example a bipolar tr nzistor, feedback elements (resistor 3 and earth) to form a chain drive of an electromagnet. The series-connected diodes 4 and resistor 5 form a circuit for the discharge of the magnetic energy of the electromagnet. The reference voltage source E, the resistors 6-8 (included in the tunable voltage divider), form the field current master, the output of which is taken from the resistor 7. The electronic switch 9, for example, a MOS transistor, is connected to the field current master circuit and serves switch its settings levels. Comparator 10, for example an operational amplifier. the capacitor 11 and the resistor 12 form a cyclic mode driver, the input of which is connected according to the voltage comparison circuit on resistors 3 and 7, and the output is connected through the resistor 13 to the base of transistor 2. The counting element 14 is connected to the output of the cyclic mode generator (for example, the comparator 10), the reset input — with the device input (Ugx input source), and the output — with the control input of the electronic switch 9. The electronic switch 15, for example, a MOS transistor, is connected to the control input roystva and switching electrodes - with drive current setpoint circuit. As a scaling element 14, Johnson's binary counter can be used, then the counter output performs the function of a counting input, its R input is a reset input, which prohibits the inverse V input of the counter. Can be connected to its output. The comparator 10 may have an additional gate (prohibiting) input. In this case, the electronic key 15 may be connected to the gate input of the comparator 10, and the common point of the key 9 and resistor 6 is connected to the reference voltage source BOL. The device works as follows. In the initial state, when a positive signal is applied, the transistor 15 is closed, the counter 14 is zero, the transistor 9 is open, the voltage on the resistor 7 and the output signal of the comparator 10 are zero, the capacitor 11 is discharged, the transistor 2 is closed, the excitation current in the electromagnet 1 and the voltage on the resistor 3 are equal to the steering wheel. When the UBX signal is removed, the device establishes a cyclical process of pulse stabilization of the specified value of the excitation current of the electromagnet as follows. The transistor 15 is opened, and a positive reference voltage (corresponding to a given level of the attractive current of the electromagnet) appears abruptly on the resistor 7. A positive voltage appears at the output of the comparator 10, the capacitor 11 recharges in time to the positive voltage of the comparator 10 through resistors 12 and 7, the transistor 2 opens, and an exponentially increasing current flows in the electromagnet winding. At the moment when the excitation current reaches a predetermined level (the attraction current) and exceeds it by a small amount, the voltage across resistor 3 also exceeds the voltage across resistor 7, the output voltage of the comparator 10 abruptly drops to zero. The capacitor 11 starts to discharge through the resistors 7 ti 12. The exponentially falling capacitor current And creates a negative voltage on the resistor 7, holding the switch 10 in the zeroed state for a constant delay time to- Transistor 2 is locked for time to, the excitation current of electromagnet 1 drops exponentially in time, flow through resistor 5 and diode 4 due to self-induced emf, the voltage across resistor 3 is zero.

After a time to when the first cycle of operation of the device ends, the output of the comparator 10 again produces a positive voltage, and the cycle of operation of the device repeats. This is how the cyclic process of the device operation is established, when the duration of the closed state of transistor 2 is constant and equal to tp, and the duration of the open state tu is automatically controlled, providing a pulse stabilization of a given value of the excitation current of the electromagnet (the duration of each cycle, starting from the second, is significantly less the duration of the first cycle, since the excitation current in the electromagnet in the first cycle increases from zero, and in the subsequent from a nonzero value, somewhat less than the specified ur ext).

Starting from the first cycle, the voltage pulses from the output of the comparator 10 arrive at the C input of the counter 14. After a predetermined number of cycles (for example, at the beginning of the fourth cycle), the output of the counter 14 generates a pulse that enters the V input of the counter and stops it condition. In this case, the transistor 9 is locked, the field current setpoint jumps to a lower level (corresponding to a given level of holding current of the electromagnet). The step of forcing an electromagnet ends, and the device begins to provide a pulse stabilization of a new lower value of the excitation current of the electromagnet (holding current).

When giving a signal Ugx. The device switches to the home state.

Thus, by introducing a recalculating element in the device, a fixed number of cycles of operation in the forcing stage is achieved, thereby increasing the stability of its operation and reducing energy consumption.

Using a counting element instead of a pulse accumulator link simplifies the proposed device.

Claims (2)

1. US Patent No. 3549955, cl. H 01 H 47/32, 1970. 2. USSR author's certificate for application number 2790970/07, cl. H 01 H 47/32, 1979.