SU1411964A2 - Method of switching an inductance load - Google Patents

Abstract

The invention relates to power switching technology and can be used in inverters of DC and AC drives. The purpose of the invention is to increase the reliability of switching while reducing the pulse power during an overload. The device implementing the method contains an intermediate switching circuit 4 having an AC key 5 and a choke 6, a power source 7, current sensors 8.1 and 8.2, key management units 9.1 and 9.2 (K) 1.1, K2, consisting of elements 10.1 and 10.2 match. The device allows, after a control signal is applied to the input of the AC key 5, to generate a test current pulse delayed by time, limited in duration and dependent on the value of inversely proportional to the voltage on the fully controlled key (K) 1. Received current test pulse served on the next inclusive K 1.1

Description

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The invention relates to power I switching technology, can be used in inverters of DC and AC drives, built on power transistors operating in the mode of pulse-width modulation, and is an improvement of the invention according to the author. St. No. 1176448.

The purpose of the invention is to improve the reliability of switching while reducing the pulse power during an overload.

FIG. 1 shows a block diagram of a device implementing the proposed method; in fig. 2 - timing diagrams for the operation of the device.

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decreased to a value less than the voltage of the setpoint (4-6 V), the element 10.1 coincidence, the inputs of which receive information about the magnitude of the voltage on the key 1. 1 and the input control pulse, generates a signal to turn on the key 1.1.

The key 1 .1 remains at the same time turned on until the end of the input control pulse or until when the voltage on it exceeds the voltage of the setpoint. In idle mode for the on-switch key 1.1, which occurs when the previously loaded key is turned off 1.2, the potential changes in the code of the device. This is due to the load current, and element 10.1

The switching device contains a half-20 coincidence that can generate a controllable keys 1.1 and 1.2 by activating the key 1.1 before forming current (Fig. 1), shunting the test pulse controlled by reverse locking diodes with the 2.1 shaper 11.1 . It does not lead

and 2.2 and capacitors 3.1 and 3.2, for any disruption of the operation of the intermediate switching circuit 4, components. Load current in this case

torus consists of an alternating current key 5 and droplets 6, an additional power supply 7, current sensors 8.1 and 8.2, key control units 9.1 and 9.2 1.1 and 1.2, which receive input control pulses, as well as information1} and the voltage value key from the output bus device.

Control blocks 9.1 and 9.2 contain elements 10.1 and 10.2 coincidence, the inputs of which receive control signals and signals about the magnitude of the voltage on keys 1.1 and 1.2, and the converters 11.1 and 11.2 of current test pulse signals, whose inputs receive a control signal and voltage information on key 5, power bus 12 and 13, output bus 14.

The essence of the proposed method is that after the control signal arrives at the input of the AC key 5 and the input of the control unit, for example, 9.1 key 1.1, a time delay is formed in the driver 11.1 which is limited in duration by several microseconds and is inversely proportional from the voltage on the switched-on key 1.1, the signal of the test current pulse, which is fed to the control input of the key 1.1.

If under the action of the switching circuit 4 and the test signal through the switch-on key 1.1 on it

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flows through the closing 1st diode 2.1, shunt key 1.1,

A device that implements the proposed method works in the following way. .

Let the operating current load flows through the closing diode 2.2,

At time t (Fig. 2a), a control signal arrives at the input of block 9.1, arriving simultaneously at the inputs of the driver 11.1, the match element 10.1, the key 1.1 and the key switch 5 of the alternating current (Fig. 26). If thyristors are used as the AC key 5, the turn-on signal may be short (indicated by the dotted line). With the arrival of the control signal and the activation of the AC key 5, the current in the inductor 6 (Fig. 2g) starts to increase and the current through the closing diode 2.2 (Fig. 2e) decreases. At the moment, the load current in diode 2.2 is completely compensated by the increasing current of droplets 6. From the time t, the current in diode 2.2 changes direction to the opposite (charge dissipation takes place in the diode) and increases until the moment t 2 - until the charge dissipates in the base of diode 2.2 (Fig. 2d). From this point on, the potential change on the output bus 14 (Fig. 2g) begins and the current in the dross 3 continues to increase,

le 6 due to recharging and shunt capacitors 3.1 and 3.2. The maximum amount of current in choke 6 comes at the time tg when the voltage on the output bus 14 becomes equal to half-sum; the voltages on the tires 12 and 13, and on the choke 6 equal to zero.

After a time delay tp-t, a test control pulse is applied (Fig. 2c), the voltage on key 1.1 (Fig. 2d) decreases, becomes less than the set voltage, and the output of the coincidence element 10.1 (Fig. 2h) is generated a constant control pulse, and the key is turned on completely. At time t .., the throttle current 6 decreases to zero. On the current key diagram 1.1 (Fig. 2i), in npo the time interval, the current decrease is noticeable, due to the change in the current of the throttles during this time interval. This is followed by the termination of the control pulse (t), the resorption of charge in key 1.1 (), the decrease in current through key 1.1 () and the increase in potential on key 1.1 to the value of the supply voltage (),

The starting moment differs from the operating mode in that at the initial moment the voltage on the output bus 14 is equal to the half-sum of the supply voltages on the tires 12 and 13, and the voltage on the throttle 6 and on the key 5 is zero. at start-up time at zero load current, switching circuit 4 does not work.

The potential change on the bus 14 occurs due to test pulses, during which the voltage on the switch decreases to the set voltage, and the switch 1.1 is turned on completely.

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This ensures clear switching in any mode of operation.

In overload mode, the voltage on key 1.1 increases and the latter turns off, because the setpoint voltage in the device has a small value (4-6 V), which simultaneously reduces the switching losses, because the voltage decreases to the setpoint voltage most operating modes occur before the arrival of the test pulse.

Claims (1)

Invention Formula The method of switching inductive loads on aut. St. No. 1176448, characterized in that, in order to increase the switching reliability while simultaneously reducing the pulse power during an overload, after the control signal is applied to the AC switch of the intermediate switching circuit, the duration is limited in time and inversely proportional to the voltage on a fully controllable key, a test current pulse, supply a test current pulse to the next, inclusive fully controllable key, open the key for the full duration control signal if the voltage on the fully controllable key decreased to the setpoint voltage before the test pulse was applied, and close this key until the control signal ends, if the voltage on the fully controllable key the current pulse did not decrease to the value of the setpoint voltage due to overload.