SU1480113A1 - Switch - Google Patents

Abstract

The invention relates to automation and can be used in switching equipment for controlling the voltage of a direct current applied to an active-inductive load, such as an electric motor. The aim of the invention is to increase reliability by eliminating through currents through power switches. The goal is achieved by the introduction of trigger 12 and the element OR-NOT 11. The control keys 8 and 9 together with the trigger 12 and the element OR-HE 11 exclude the simultaneous activation of power switches 1 and 2 when signals from sensors 5 and 7 of the current and modulator 10 are applied. 2 il.

Description

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sixteen

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1

Ichobre (sleep refers to automation and can be used in switching equipment to control the DC voltage applied to an active-inductive load, such as an electric motor.

The purpose of the invention is to increase reliability by eliminating through currents through power switches.

FIG. 1 is a block diagram of a switch; figure 2 - timing charts of his work.

The switch contains the first and second power switches 1 and 2, the active-inductive load 3, the first reverse diode 4, the first current sensor 5, the second reverse diode 6, the second current sensor 7, the first and second control keys 8 and 9, and the module torus 10 duration, the element WI-NOT 11 and trigger 12.

The first and second power switches 1 and 2 are interconnected in series and connected by output terminals to the corresponding buses 13 and 14 of the bipolar power source. To the point of connection of the power switches 1 and 2, an active-inductive load 3 is connected by the first terminal, for example, the engine measles. Parallel to the first power switch 1, a chain consisting of a series-connected reverse diode 4 and current sensor 5 is turned on, and parallel to the second power switch 2 is a similar chain from the reverse diode 6 and current sensor 7. The outputs of the current sensors 5 and 7 are connected to the corresponding inputs of the OR-NOT 11 element, and its outputs are connected to the C input of the trigger 12. The antiphase outputs of the trigger 12 are connected to the corresponding control inputs of the control switches 8 and 9, the First output of the modulator 10 of duration connected via the first control switch 8 to the control input of the first power switch 1. The second output of the modulator 10 of duration is connected to the D input of the trigger 12 and through the second control switch 9 to the control input of the second power switch 2. The control pulses produce The modulators 10, the durations of the first and second outputs, are in antiphase. The input of the modulator 10 of duration is connected to the control bus 15. The second output of the loading handle 3 is connected to the midpoint 16 of the power supply sandbox.

In FIG. 2, there are: 17 — a signal at the first output of the modulator 10; 18 - signal at the output of the element OR NOT 11; 19 - signal at the inverse output of the trigger 12; 20 is a signal at the output of the control key 8; 21 is the signal at the output of the control key 9; 22 is a signal at the output of current sensor 5; 23 - output signal yes 7 current; 24 is the signal at the output of the power switch 1; 25 - signal at the output of the power switch 2.

The switch works as follows.

When a control signal is applied from the control bus 15 to the input of the modulator 10 of duration, a pulse of a duration proportional to the control signal appears at its outputs. Control pulses generated at the outputs of the modulator 10 of duration are in antiphase and provide alternate switching of power switches 1 and 2.

Consider the mode of operation of the switch, providing the movement of the core, for example, clockwise. When the first power switch 1 opens, it draws current from the power supply. When closing the power switch 1 is the closure of the load current through the diode 6.

Let the initial state of the output levels of the trigger 12 provide the open state of the first control key 8 and the closed state of the second control key 9, and the output signals from the modulator 10 also provide the open state of the first power key 1 and the closed state of the second power switch 2. Load 3 is connected to a positive polarity power source. Reverse diodes 4 and 6 are closed. The output signal from the sensors 5 and 7 is missing. A control pulse passes to the control input of the first power switch 1, and there is no signal at the control input of the second power switch 2. This state lasts until the modulator 10 of duration switches and at its first output the polarity of the control pulse is reversed. The process of closing the first power switch 1 begins. Under the action of an emf of self-induction of load 3, a diode 6 is opened, and through the sensor

7 current is flowing current. The second power switch 2 remains closed during this time interval,

When switching to the reverse rotation mode of the motor core, the distribution of currents in the circuit changes. The reverse rotation mode starts from the moment when, during the period of closing the first power switch 1, the load current flowing through diode 6 drops to zero, and the output signal of the current sensor 7 changes the state of one of the inputs of the OR-HE element 11, provides a clock pulse to the C input of the trigger 12. As a result, the signal supplied from one of the outputs of the modulator 10 of duration to the D input of the trigger 12 causes the output state to change to the opposite, which leads to the opening of the second control key 9 and for Opening the first control key 8. The control pulse, which at this time period comes from the output of the modulator 10 of duration, hits the control input of the second power key 2 and opens it. Through the open power switch 2, a current flows that causes the motor core to reverse rotation (load 3). During subsequent switching, the second power switch 2 closes and the first power switch 1 should open. But when the second power switch 2 is closed, under the action of the self-induced EMF of the load 3, the reverse diode 4 is opened, and a current flows through the current sensor 5. After current of current sensor 5 drops to zero, its output signal, changing the level state of one of the inputs of the element OR NOT 11, provides a clock pulse to the C input of the trigger 12, resulting in a signal from the output of the modulator 10 of duration to the trigger input 12 leads to a change in the state of its outputs to the opposite, which ensures the opening of the second control key 9 and the closing of the first control key 8. The control pulse, which during this period of time comes from the output of the modulator 10 duration, t to the control terminal of the first MOSFET 1 and opens it. Through the open power switch current flows corresponding to the desired mode of operation of the engine.

Thus, the control switches 8 and 9 together with the trigger 12 and the element OR-HE 11 provide, when exposed to signals from the current sensors 5 and 7 and the modulator 10, the activation of the power switches 1 and 2 only in cases when it is required in depending on the mode of operation. The use of a bipolar power source allows the direction of movement of the engine core to be changed, if necessary. The switch eliminates the simultaneous presence of power switches 1 and 2 in the open state as a result of signals from current sensors 5 and 7 through the element ORIN and trigger 12 to the control inputs of keys 8 and 9. This leads to the elimination of through currents through the power switches and improve the reliability of the device.

Claims (1)

Invention Formula A switch containing a duration modulator, the input of which is connected to the control bus, the first and second outputs of the duration modulator are connected to the inputs of the first and second control keys, respectively, whose outputs are connected to the control inputs of the first and second power switches, respectively, of which are connected to plus and minus power buses, the outputs of the power switches are connected to the first load output, the first and second power switches are shunted connected in series, respectively The first and second reverse diode and current sensor, distinguished by the fact that, in order to increase reliability by eliminating through currents through power switches, a trigger and an OR-NOT element are introduced, the first and second inputs of which are connected respectively to the outputs of the first and second current sensors, the output of the element OR is NOT connected to the C input of the trigger, the D input of which is connected to the second output of the modulator of duration, the inverse output of the trigger connected to the control input of the first control key, and the direct output to the control entrance second On the control key, the second load terminal is connected to the midpoint of the power source. 2.