SU519728A1 - Device for modeling an electrical circuit with triac - Google Patents

Description

one

The device relates to the field of computing and converting electrical engineering, is used in the study of electrical processes in valve converters.

A device for simulating an electrical circuit comprising anti-parallel thyristors or a triac (symmetrical thyristor) is known.

Such a device includes a control pulse shaping unit, a control block and an adder with a first control key in the feedback circuit, the inputs of which are connected respectively to an input voltage source, an output of a load voltage shaping unit and an output of an inverter connected to the output an adder via an integrator, in the feedback circuits of which through the second and third controlled keys, respectively, turn on anti-parallel diodes controlling the sign of the input voltage. The inverter output is connected to the comparator input and the first input of the load voltage shaping unit, the second input of which is connected to the output of the adder.

The drawbacks of the device are comparatively low reproducibility of the characteristic of the triac and the absence in the model of a signal proportional to the derivative of the simulated current, which is necessary for the formation of a load voltage. In the proposed device, in order to improve accuracy, the control unit contains the elements "AND," OR, "NOT and triggers, the first inputs of which are connected to the outputs of the corresponding elements" AND, the first inputs of the elements to the outputs of the comparator, and the second inputs of the triggers - to the same outputs through the elements "NOT. The outputs of the forming unit of control pulses are connected to the second inputs of the AND elements, the control inputs of the second and third controlled keys, and the first inputs of the first and second OR elements, the second inputs of which

connected to the outputs of the triggers, and their outputs through the third element "OR - to the control input of the first control key. N. on the drawing shows the scheme of the proposed device.

The device contains an adder 1, an integrator 2, an inverter 3, controllable switches 4, 5, 6, diodes 7 and 8, a comparator 9, a load voltage shaping unit 10, elements "And 11, 12, elements" NOT 13 and 14, triggers 15 and 16,

the elements OR 17, 18, 19 and the control pulse shaping unit 20. Elements 11-19 are part of the control unit 21. The device works as follows. In the feedback of the integrator 2, the controllable keys 5, 6 are installed, in series with which the diodes 7 and 8 are connected in different directions. These circuits provide control of the anode voltage of the triac. The key 5 (6) closes in the corresponding half-period of the input voltage when a pulse arrives from the control pulse shaping unit 20. If at this moment there is a corresponding polarity at the input of integrator 2 (positive for key 6, negative for key 5), then the integration process begins and the current through the triac is simulated at the chosen scale. The device remains in operation until the simulated current drops to zero. In this case, the signal from one of the outputs of the comparator 9 disappears and the key 4 closes, stopping the operation of the device. If by the time the control pulse arrives from block 20 at the input of integrator 2 there is an inappropriate polarity, then the integrator is shunted by diode 7 (or 8), and the closed triac mode is maintained. The load voltage is modeled by the load voltage shaping unit 10, the structure of which is determined by the type of load.

The sign of the simulated current is controlled by a comparator 9 with two outputs (a three-point trigger). The presence of a signal at one of the comparator outputs indicates a certain polarity of the simulated current. The signals from the comparator outputs are fed to one input of the And 11 and 12 elements, and to the other inputs of these elements, control signals are generated by the control pulse shaping unit 20 at a certain point in time. At the same time, the signal from the output of the comparator 9 is fed to the element "NOT 13 or 14. The outputs of the elements" And 11 or 12 and "NOT 13 or 14 are connected to the input of the trigger 15 or 16. Signals from the outputs of the trigger 15, 16 are passed to the elements" OR 17 and 18, to the second inputs of which the control pulse signals are received again. The output signal from the element OR 19 controls the key 4 in the feedback circuit of adder 1.

The above connection of logic elements ensures reliable control of the key 4, and consequently, the operation of the entire device at arbitrarily small deadband of the comparator 9, since the signals from its output cannot open the key 4 when there is no control signal.

The control unit 21 of the device operates as follows.

With the appearance of a control pulse, it passes through the elements OR 17, 19 and opens the key 4. At this moment, the current is zero and there is no signal at the output of the apartment 9. With the corresponding polarity, a valve current is formed at the input of the integrator 2, the comparator 9 outputs a signal that goes to one input of the element "AND 11. To the second input of this element at the same time

an unfinished control impulse is applied. The signal from the output of the element "And 11 triggers the trigger 15, and the signal from its output through the elements" OR 17 and 19

maintains key 4 in an open-state after termination of the control pulse. In the case of a decrease in the current elemeite "And 11 to zero at the output of komnaratora 9, the signal disappears, and the second input of the trigger 15 through the element" NOT i3 receives a pulse, which translates the trigger 15 into the opposite state and removes the signal from its output. Key 4 closes, terminating the integration process. If a decrease in the current element "And 11 he

replacing) 1T is your sign, this will cause a signal to appear at the second output of comparator 9. However, this will not lead to a false trigger of key 4 due to the operation of elements 12, 16, 18, 19 of the control unit, since at this moment

there is no control pulse and the trigger 16 does not fire.

The use of the proposed structure of the device for simulating the operation of a snmpstore allows the creation of more efficient models of reversible valve converters, increasing their reliability and accuracy of modeling.

Claims (1)

Invention Formula A device for simulating an electric circuit with a triac, containing a control pulse shaping unit, a control unit and an adder with a first control unit the key in the feedback circuit, the inputs of which are connected respectively to the input voltage source, the output of the load voltage shaping unit and the output of the inverter, whose input is connected to the output an adder via an integrator, in the feedback circuits of which through the second and third controlled keys, respectively, turn on anti-parallel diodes controlling the sign of the input voltage; the inverter output is connected to the input of the comparator and the first input of the load voltage shaping unit, the second input of which is connected to the output of the adder, characterized in that, in order to increase the accuracy, therein the control block contains elements "AND," OR, "NOT and triggers, the first inputs of which are connected to the outputs of the corresponding elements" AND, the first inputs of which are connected to the outputs of the comparator, the second inputs of the triggers are connected to the same outputs through the elements "NOT, the outputs of the shaping control unit the pulses are connected to the second inputs of the AND elements, the control inputs of the second and third controlled keys and the first inputs of the first and second OR elements, the second inputs of which are connected to the trigger outputs, and their outputs through the third OR element dinene with the control input of the first control key.