RU106464U1 - HIGH VOLTAGE VENT MODULE - Google Patents

Abstract

The utility model relates to electrical engineering, in particular, to the areas of automated electric drive and converter technology. The high-voltage valve module contains n series-connected thyristors or triacs shunted by protective RC circuits, a control and protection unit, as well as thyristor control devices containing a diode rectifier and threshold and optocoupler elements in parallel, while the optocoupler element is connected via an output circuit to the input of the unit control and protection, and the inputs of the diode rectifier are connected in series with protective RC circuits of a pair of series-connected thyristors or triacs, the outputs are with a threshold element m and one of the outputs - with a common point of a pair of series-connected thyristors or triacs. The utility model allows to simplify the design of the valve module and increase the reliability of its operation.

Description

The utility model relates to electrical engineering, in particular, to the areas of automated electric drive and converter technology.

Known high-voltage valve modules, widely used in soft starters of powerful AC electric motors of medium voltage 6 (10) kV [1]. These modules contain n (for example, 4 or 6) series-connected thyristors or triacs (counter-connected pairs of thyristors), each of which is shunted by a protective RC circuit, and N thyristor health monitoring devices. Thyristor health monitoring devices consist of series-connected voltage divider, diode bridge, threshold and optocoupler elements. The output of the optocoupler element is connected to the input of the control and protection unit. If one or more thyristors of the valve module fails, the voltage at the successively connected operational thyristors rises. Thyristor operability monitoring devices detect an increase in voltage at the thyristors and transmit an alarm signal to the control and protection unit via optocouplers.

The disadvantage of this device is the low sensitivity of the algorithm for detecting a faulty thyristor implemented in it - the more thyristors are connected in series, the less the voltage increases for healthy ones when one fails. Accordingly, thyristor control devices may not detect a malfunction with a typical tolerance of Δ = ± 5% for the deviation of the parameters of the elements.

The closest in technical essence to the claimed device and taken as a prototype is a high-voltage gate module [2], containing n series-connected thyristors or triacs shunted by protective RC circuits, a control and protection unit, as well as N thyristor control units containing a threshold and an optocoupler elements connected in parallel and connected to the circuit between the thyristor and the RC circuit, while the output of the optocoupler element is connected to the input of the control and protection unit.

This device implements an algorithm for detecting a faulty thyristor by the amount of current in the protective RC circuit. Accordingly, when the thyristor fails, the RC circuit is shorted and there is no controlled current i _RC , and the thyristor control device clearly detects the thyristor emergency state (i _RC = 0) with a typical tolerance for deviation of the parameters of the elements of the high-voltage valve module.

However, the thyristor malfunction detection algorithm implemented in the device contains a significant number of control devices in which the optocoupler element is implemented using fiber-optic alarm transmission to the control and protection unit. In medium voltage devices of 6 (10) kV, according to the rules of the PUE, this communication channel must withstand a test voltage of 36 (42) kV. Accordingly, the design of the device, as a whole, should be designed to meet the specified requirements for protective distances along the surface of the optical fiber connection. As a result, the design of the high-voltage valve module is complicated and the reliability of its operation is reduced. The failure rate increases in proportion to the number of elements in the device.

The technical result is to simplify the design and increase the reliability of the claimed device.

The technical result is achieved in that in a high-voltage valve module containing n series-connected thyristors or triacs, shunted by protective RC circuits, a control and protection unit, as well as thyristor control devices containing threshold and optocoupler elements connected in parallel, the latter being connected via a circuit an output to the input of the control and protection unit, a diode rectifier is introduced into the thyristor control device, the inputs of which are connected in series with the protective RC circuits of the pair in series thyristors or triacs, outputs - with a threshold element, and one of the outputs - with a common point of a pair of series-connected thyristors or triacs.

A distinctive feature of the utility model is that a simplification and increase in the reliability of the high-voltage gate module is achieved due to the fact that a diode rectifier is inserted into the thyristor control device, the inputs of which are connected in series with protective RC circuits of a pair of connected thyristors or triacs, and the outputs have a threshold element , and one of the outputs - with a common point of a pair of series-connected thyristors or triacs. This allows you to identify the malfunctioning state of a pair of thyristors using a single control device.

Thus, in a high-voltage valve module, the required number of thyristor control devices is halved, which simplifies its design and reduces the failure rate.

Figure 1 shows a diagram of the inventive high-voltage valve module, which adopted the following notation:

1, 2 ... (n-1), n - series-connected thyristors or triacs (counterclosed pairs of thyristors);

3, 4- protective RC circuits;

5 - control and protection unit;

6 - thyristor control devices;

7 - threshold element, for example, a zener diode;

8 is an optical element containing a semiconductor emitter, an optical fiber transmission channel and an optical detector, for example, a phototransistor;

9 - diode rectifier (single-phase bridge).

Figure 2 shows a diagram of a soft starter for a high-voltage AC motor [3], made on the basis of three high-voltage valve modules according to the scheme of a three-phase thyristor (triac) regulator of alternating voltage (current), where the following notation:

VVM1 ... VVM3 - high-voltage valve modules;

M1 - AC electric motor;

~ U _P - voltage of the three-phase supply network.

Figure 3 presents the timing diagrams of signals (voltages, currents) on the main elements of the device:

U1 (2) - voltage on thyristors 1 and 2;

i3 (4) - currents in protective RC circuits 3 and 4;

I _CP is the sensitivity threshold of the optocoupler element;

i8 is the current in the circuit of the emitter of the optocoupler element;

T is the time period of the supply voltage;

8 - state of the output circuit of the optocoupler element (phototransistor).

The proposed high-voltage valve module contains n series-connected thyristors (triacs) 1, 2 ... n-1, n, shunted by protective RC circuits 3, 4, a control and protection unit 5 and thyristor control devices 6, consisting of a parallel threshold 7 and an optocoupler 8 elements and a diode rectifier 9. An optocoupler 8 is connected to the input of the control and protection unit 5 through the output circuit, the inputs of the diode rectifier 9 are connected in series with protective RC circuits 3, 4 pairs of series-connected thyristors (triacs) 1, 2, output a rectifier diode 9 are connected to the threshold element 7, and one of the outputs of rectifier diode 9 is connected to the junction of serially connected pairs of thyristors (Triac) 1, 2.

The operation of the inventive high-voltage valve module (VVM) in the test mode of operability of series-connected thyristors or triacs (counter-coupled pairs of thyristors) will be considered using the example of a soft starter (soft starter) of a high-voltage alternating current motor M1 (see Fig. 2). The soft starter is a three-phase thyristor AC voltage regulator made on three modules VVM1 ... VVM3. Testing of VVM is carried out when connecting the soft starter to the mains. The voltage applied to the VVM is evenly distributed on serviceable series-connected thyristors (triacs) 1, 2 ... (n-1), n at the level due to the protective RC circuits 3, 4 (see figure 1). The current of the protective RC circuits 3, 4 (i ₃ = i ₄ ) flows through the diode rectifier 9, the input circuit of the optocoupler element 8 and is defined as:

i ₃ = i ₄ ≈U ₃ · ω · C = U ₄ · ω · C,

where, U ₃ , U ₄ are the voltages on the RC circuits 3, 4;

ω is the frequency of the supply network;

C is the value of the capacitor in the RC circuit.

In the output circuit of the optocoupler element, an optical receiver, such as a phototransistor, is opened. Accordingly, the input “I” is fed to the input I of the control and protection unit 5 from the output of the optocoupler 8. With a positive current polarity of the RC circuits 3, 4 and operational thyristors (triacs) 1, 2, the current flows through the diode “a” of the rectifier 9, the emitter of the optocoupler element 8 and the diode “b” of the rectifier 9. With a negative polarity of the current of the RC circuits through the diode “d”, the emitter 8 and the diode “c” of the diode rectifier 9. The emitter 8 transmits a signal “Open” of the thyristors in good condition through the fiber ( triacs) 1, 2 to the input I of the control unit and protections 5.

Thus, at each time period T of the mains voltage, the thyristor control unit 6, consisting of a diode rectifier 9, a threshold 7 and an optocoupler 8 elements, alternately transmits two “Open” signals to the input I of the control and protection unit 5, informing about the working condition of the two series-connected thyristors (triacs) 1, 2 (see figure 3, a).

In the event of a malfunction of one of the thyristors, for example, thyristor 1, the latter shunts the RC circuit 3 (i ₃ = 0). With a positive current polarity of the RC circuit 4, the current flows through the faulty thyristor 1, the diode "B" of the rectifier 9 and the RC circuit 4, and with a negative polarity through the faulty thyristor 1, the emitter 8, the diode "C" and the RC-pin 4. Accordingly , the emitter 8 transmits to the input I of the control and protection unit 5 the signal “Open” only with a negative polarity of the current (voltage) of the supply network.

Thus, when the thyristor 1 is faulty, the signal “Open” is not transmitted to the input I of the control and protection unit 5 with positive polarity of the current (voltage) and the signal “Open” is transmitted when the polarity is negative, informing about the operational state of thyristor 2 (see. 3b). Similarly, the procedure for detecting a faulty thyristor 2 occurs, with the only difference being that the faulty state of thyristor 2 is fixed by the absence of the “Open” signal with negative polarity, and the health of thyristor 1 - by the presence of the “Open” signal with positive polarity.

In the event of a malfunction of two thyristors 1 and 2, the RC circuits 3, 4 are bridged by faulty thyristors, and the thyristor control unit 6 does not transmit the signal “Open” to input I of the control and protection unit 5 (see Fig. 3, c).

Thus, in the inventive device, reliable monitoring of the state of each pair of series-connected thyristors (triacs) is implemented using an originally executed one thyristor control unit that transmits information to the control unit:

- about the serviceability of series-connected thyristors in the form of two “Open” signals for a period of time T of the supply voltage;

- about the malfunction of one of the thyristors in the form of a single signal "Open" for a period of time T;

- about the malfunction of two series-connected thyristors in the form of the absence of “Open” signals.

If necessary, the thyristor number is determined (even or odd) by the polarity of the supply voltage.

As a result, the number of thyristor control units for testing series-connected VVM thyristors and the number of control unit inputs is reduced by half, which, in general, simplifies the device and increases its reliability. At the same time, the positive properties of the prototype are retained - increased sensitivity when testing the thyristor serviceability and the ability to check the phasing of the control pulses of the thyristors.

Sources of fame

[1] RF patent for utility model No. 31886 "High-voltage valve module" dated 03.03.2003.

[2] Patent for utility model No. 101584 "High-voltage valve module" dated 08.27.2010

[3] Ivanov A.G. et al. Algorithms for switching and modeling devices for soft start of electric motors - “Electrical Engineering” 2006, No. 10, p. 61.

Claims (1)

A high-voltage valve module containing n series-connected thyristors or triacs shunted by protective RC circuits, a control and protection unit, as well as thyristor control devices containing threshold and optronic elements connected in parallel, the latter connected via an output circuit to the input of the control and protection unit characterized in that a diode rectifier is inserted into the thyristor control device, the inputs of which are connected in series with protective RC circuits of a pair of serially connected thyristors or triacs, outputs - with the threshold element, and one of the outputs - to the common point of serially connected pairs of thyristors or triacs.