RU2565598C1 - Control system of group of electric drives with parallel control channels - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: control system of a group of electric drives with parallel control channels includes a multizone scanning converter consisting of adders, an integrator, relay elements, a setup signal source, smoothing filters, for example of the first order, additional relay elements, voltage controls for smooth start of asynchronous electric motors, water pumps, a discharge water main line, nOR logic element, and "frequency - logic signal" converters. The control system includes n≥3 of an unequal number of "frequency - logic signal" converters and nOR logic element. Inputs of "frequency - logic signal" converters are connected to the output of the corresponding relay element of the group of n≥3 relay elements, and outputs of "frequency - logic signal" converters are connected to the corresponding inputs of nOR logic element, the output of which is connected to the input of emergency trip of voltage controls.

EFFECT: improving operating reliability of a control system of a group of electric drives.

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Description

The invention relates to the field of electric drive and can be used in the automation of technological processes for controlling a group of asynchronous electric motors running in parallel.

A known control system with automatic redundancy (Tsytovich L.I.A. 1294152 USSR, G05B 9/03, H05K 10/100. Redundant automatic drive control system. No. 3920771/24, announced 02.08.85, publ. 07.02.87 , bull. No. 5), containing integrating deploying converters, diagnostic blocks, feedback sensors, key switch, actuator. The disadvantage of this device is its lack of reliability due to the lack of diagnostic tools for key switches.

Known electric drive (AS 913824 USSR, G05B 11/01. Tracking electric drive / Tsytovich LI (USSR) .- No. 3007071/24, announced 19.11.80, publ. 15.03.82, bull. No. 10), characterized by increased noise immunity, which includes an electric motor, a pulse-width converter based on an integrator and a relay element. The disadvantage of this device is the low reliability due to the lack of redundant channels for converting control actions and automatic diagnostics.

Known multi-zone integrating deploying converter (AS 1283801 USSR, G06G 7/12. Deploying converter / Tsytovich LI (USSR). - No. 3945653/24, stated 05.22.85, publ. 15.01.87, bull. No. 2), containing adders, a group of parallel operating integrators, an odd number of relay elements.

The device is characterized by high reliability in operation and belongs to the class of systems with self-diagnosis of active components of the circuit and automatic commissioning of workable elements.

A disadvantage of the known technical solution is the inability to automatically enter the operation of electric motors, or other actuators, controlled by the output signals of relay elements. As a result, having its own high reliability, the known device is not able to provide automatic backup of the external power units controlled by it.

Closest to the proposed device is a control system according to patent RU No. 2312452 "Control system for a group of electric drives of water pumps", publ. 12/10/2007, bull. Number 34. The control system contains a sequentially connected reference signal source, a multi-zone deployment converter, consisting of a first adder, an integrator, the output of which is connected to a group of n-th number of relay elements, n≥3 is an odd number, the outputs of which are connected to the corresponding inputs of the second adder, the output of which is connected to the second input of the first adder, and n≥3 is an odd number of groups, each of which consists of a series-connected voltage regulator of an induction motor I and a water pump, the outputs of which are connected to a common water line, moreover, in each of the indicated groups of n≥3 - an odd number a smoothing filter and an additional relay element are introduced in series, the input of each smoothing filter connected to the output of the corresponding relay element, and the output each of the additional relay elements is connected to the input of the corresponding voltage regulator.

The disadvantage of the prototype device is that in case of failure of the power source of the information part of the system, in particular the multi-zone controller, all actuators can turn on, which will lead to an increase in pressure in the output line and its rupture.

Thus, the prototype device has a low reliability when working as part of a control system, for example, water supply.

The basis of the invention is the technical task of improving the reliability of the control system of a group of electric drives of water pumps.

The proposed control system for a group of electric drives with parallel control channels contains a sequentially connected reference signal source, a multi-zone deployment transducer, consisting of a first adder, an integrator, the output of which is connected to a group of n-th number of relay elements, and n≥3 is an odd number, the outputs of which connected to the corresponding inputs of the second adder, the output of which is connected to the second input of the first adder, and n≥3 is an odd number of groups, each of which consists of of a smoothly connected smoothing filter, an additional relay element, an asynchronous electric motor voltage regulator with an emergency shutdown input and a water pump, the output of which is connected to a common water main, and DIFFERENT from the known that n≥3 is entered into it - an odd number of frequency-logical converters signal "and the logic element" nOR ", and the inputs of the frequency-logic signal converters are connected to the output of the corresponding relay group of n≥3 relay elements, and the outputs of the converter s "frequency - the logical signal" connected to respective inputs of NAND gate "nOr", the output of which is connected to the input of the emergency shutdown of the voltage regulator.

The stated technical problem is achieved due to the fact that n≥3 is entered into the control system - an odd number of frequency-logic signal converters and an "OR" logic element, and the inputs of frequency-logic signal converters are connected to the output of the corresponding group n≥≥ 3 relay elements, and the outputs of the frequency-to-logic-signal converters are connected to the corresponding inputs of the “OR” logic element, the output of which is connected to the emergency shutdown input of voltage regulators. In this case, in the event of a power failure of the multi-zone controller, including the first and second adders, an integrator and a group of the nth odd number (n≥3) of relay elements, an emergency disconnection from the network of voltage regulators and a forced shutdown of the asynchronous actuators are forced. This eliminates the possibility of occurrence of multiple faults at the facility.

The invention is illustrated by the following drawings:

FIG. 1 is a structural diagram of the proposed device;

FIG. 2 - structure and diagrams of the signals of the frequency-logical signal converters;

FIG. 3 - characteristics of relay elements;

FIG. 4 - timing diagrams of the signals of the proposed device.

The device (Fig. 1) includes adders 1, 2, an integrator 3, relay elements 4-1 ... 4-n, smoothing filters 5-1 ... 5-n, additional relay elements 6-1 ... 6-n, voltage regulators (PH) 7-1 ... 7-n, executive asynchronous motors 8-1 ... 8-n, water pumps 9-1 ... 9-n, water outlet 10, frequency-logical-signal converters (CLS) 11-1 ... 11-n, logical element "nOR" 12.

HLS 11-1 ... 11-n contain (Fig. 2a) a frequency divider 13, a proportionally differentiating link 14 and a demodulator 15.

RN 7-1 ... 7-n are made according to the standard structure (see, for example, Tsytovich LI, Gafiyatullin R.Kh., Maurer V.G., Rakhmatulin PM Integrating deploying system of pulse-phase control of thyristor converters for electric drives with Limited-power power supplies.Electrotechnical systems and complexes. Interuniversity collection of scientific works, MGMA, Magnitogorsk, 1996, pp. 29-38; Gafiyatullin R.Kh., Tsytovich L.I., Maurer V.G., Rakhmatulin PM Complex thyristor converters for soft start of asynchronous electric motors // Scientific and technical seminar p “75 years of the national school of electric drives”, abstract of reports, St. Petersburg, 1997, p. 50.) and contain an emergency shutdown input, when a logical “0” signal is applied, the LV is disconnected from the network.

Elements of the proposed device have the following characteristics.

Adders 1, 2 implement a linear non-inverting characteristic “input-output” and a single transfer coefficient for each of the inputs.

Integrator 3 is implemented according to a typical circuit on an operational amplifier with a capacitor in the feedback circuit. When the jump of the input signal, for example, positive polarity, the output signal of the integrator 3 changes linearly with a sign opposite to the sign of the input effect.

Relay elements (RE) 4-1 ... 4-n have a zero-symmetric non-inverting hysteresis loop (Fig. 3, a) with switching thresholds ± b _i . The output signal of the relay elements 4-1 ... 4-n varies discretely within ± A / n, where n≥3 is an odd number.

Additional relay elements 6-1 ... 6-n are made with the characteristic shown in FIG. 3b, and have threshold levels of operation C ₁ > C ₂ . The output signal of the relay elements 6-1 ... 6-n varies discretely from "0" to "+ A".

The launch of the pH 7-1 ... 7-n (Fig. 1) is performed by the signal "+ A" (logical "1"). The start condition is also the presence of the signal “1” at the output of the logic element 12 of the “OR” function, which is fed to the emergency shutdown inputs of the PH 7-1 ... 7-n. On the start-up interval, the stator current of electric motors 8-1 ... 8-n is limited at a predetermined level due to the feedback loop for the stator current and the integral current regulator PH 7-1 ... 7-n. The pH 7-1 ... 7-n is switched to the closed state and the actuators 8-1 ... 8-n and 9-1 ... 9-n are braked by a logic signal “0” at the input of the LV emergency shutdown.

The frequency divider 13 (Fig. 2A) is switched, for example, on the leading edge of the pulses from the output of the corresponding relay elements 4-1 ... 4-n. The proportional-differentiating link 14 passes to the output only the variable component of the output pulses of the frequency divider 14, which has a division coefficient equal to 2.0. The demodulator 15 carries out the rectification of the variable signal from the output of the proportionally differentiating link 14.

In FIG. 1-4 introduced the following notation:

X _VX - input signal of the control system;

Y _And (t) is the output signal of the integrator 3;

Y _P1 (t), Y _P2 (t), Y _P3 (t) - output signals of relay elements 4-1, 4-2, 4-3, respectively;

± b ₁ , ± b ₂ , ± b ₃ - switching thresholds of relay elements 4-1, 4-2, 4-3, respectively;

± A / 3 - the amplitude of the output pulses of the relay links 4-1, 4-2, 4-3 and the adder 2;

± A is the maximum amplitude of the output signal of the integrator 3 and adder 2;

Y _Фl (t), Y _Ф2 (t), Y _Ф3 (t) - output signals of smoothing filters 5-1, 5-2, 5-3, respectively;

Y ₀₁ , Y ₀₂ , Y ₀₃ - output signals of additional relay elements 6-1, 6-2, 6-3, respectively;

Y _OUT (t) - the output signal of the adder 2;

Y ₀ - the average value of the pulses at the output of the adder 2;

Υ _H is the maximum output signal of the integrator 3;

Y _PM (t) is the output signal of the frequency divider (counting trigger) 13;

Y _D (t) is the output signal of the proportionally differentiating link 14;

Y _In (t) is the output signal of the demodulator (rectifier) 15;

T _0i is the period of the output pulses of the relay elements 4-1, 4-2, 4-3 and the adder 2;

T _And - the time constant of the integrator 3;

T_one, T₂ - time constants of the proportionally differentiating link 14.

The principle of operation of the device is as follows.

Links 1, 2, 4-1 ... 4-3 (Fig. 1) in the aggregate form a multi-zone integrating deploying controller (MP) with pulse-frequency pulse-width modulation. In the general case, the number of relay elements must satisfy the condition n≥3 - an odd number, and to get the required number of "k" modulation zones, n = 2k-1 is necessary. In the future, we restrict ourselves to the number of relay elements n = 3.

Consider the operation of the system without elements 11-1 ... 11-3, assuming that the enable signal “1” is applied to the emergency shutdown input of the PH 7-1 ... 7-3, for example, from the control system’s own power source.

Two of the executive channels, for example 5-1, 6-1, 7-1, 8-1, 9-1 and 5-2, 6-2, 7-2, 8-2, 9-2, are reserve, and the third - 5-3, 6-3, 7-3, 8-3, 9-3 - to the workers. It should be noted here that the division of electric drives into working and standby is conditional, since with the appropriate choice of system parameters, as will be shown below, any of the executive channels can be either a working or standby drive.

Relay elements 4-1 ... 4-3 have a non-inverting hysteresis loop symmetrical with respect to the zero level and switching thresholds satisfying the condition | ± b ₁ | <| ± b ₂ | <| ± b ₃ | (Fig. 4b). The output signal of all relay elements varies discretely within ± A / n (in this case ± A / 3). Hereinafter, we believe that the change in the level of the input signal coincides with the beginning of the next cycle of the developing transform (sign change of the derivative of the output signal of the integrator 3).

When you turn on the MP and the zero input signal X _BX RE 4-1 ... 4-3 are set arbitrarily, for example, in the state + A / 3 (Fig. 4c-d). Under the influence of the scanning signal _and Y (t) outputted from the integrator 3 (Fig. 4b) are sequentially switched to position -A / 3 blocks 4-1, 4-2 (Fig. 4c, d, time points t _01, t ₀₂₎ , after which the direction of the sweeping transformation changes, and the signal Y _AND (t) grows in the positive direction. Starting from the moment of fulfillment of the condition Y _И (t) = b ₁ , MP enters the stable self-oscillation mode when the amplitude of the scanning signal Y _И (t) is limited by the ambiguity zone of the relay element 4-1, which has the minimum switching thresholds, and the relay elements 4 -2 and 4-3 are in static and opposite in sign output signals Y _P2 (t), Y _P3 (t) states (Fig. 4d, d). The output coordinate Y _OUT (t) MP is formed due to the switching of RE 4-1 (Fig. 4c) in the first modulation zone, limited by ± A / 3 (Fig. 4e). In the absence of X _BX (Fig. 4a, t <t ₀ ), the average value Y _{0 of the} pulses Y _OUT (t) is zero.

) влечет за собой изменение частоты и скважности импульсов Y_ВЫХ(t), так как в интервале t₁ (фиг. 4в) развертка Y_И(t) (фиг. 4б) изменяется под действием разности сигналов, подаваемых на сумматор 1 (фиг. 4а, е), а в интервале t₂ - dY_И(t)/dt зависит от суммы этих воздействий. В результате Υ₀=X_ВХ (фиг. 4е).The presence of the input coordinate X _BX <(A / 3) (Fig. 4A,

) entails a change in the frequency and duty cycle of the pulses Y _OUT (t), since in the interval t ₁ (Fig. 4c) the scan Y _AND (t) (Fig. 4b) changes under the influence of the difference of the signals supplied to the adder 1 (Fig. 4a, e), and in the interval t ₂ - dY _AND (t) / dt depends on the sum of these effects. As a result, Υ ₀ = X _BX (Fig. 4e).

сигнал X_ВХ увеличился дискретно до величины (A/3)<X_ВХ<A (фиг. 4а). Это нарушает условия существования режима автоколебаний в первой модуляционной зоне, и MP переходит на этап переориентации состояний РЭ 4-2, 4-3, который заканчивается в момент времени t₀₃, когда РЭ 4-3 переключается в идентичное положение -A/3 (фиг. 4д). Координата Y_ВЫХ(t) достигает уровня -A (фиг. 4е), и MP переходит во вторую модуляционную зону, где в интервалах t₁, t₂ (фиг. 4в) скорость формирования сигнала развертки Y_И(t) (фиг. 4б) также определяется разностью или суммой сигналов, воздействующих на сумматор 1. При этом сигнал Y₀ включает постоянную составляющую -A/3 и среднее значение импульсного потока Y_ВЫХ(t) второй модуляционной зоны (фиг. 4е). Переход MP из одной модуляционной зоны в другую для малых приращений координаты X_ВХ сопровождается переходом системы через характерные точки с нулевым значением частоты несущих колебаний (режим частотно-нулевого сопряжения модуляционных зон).Assume that at time

the signal X _BX increased discretely to a value of (A / 3) <X _BX <A (Fig. 4a). This violates the conditions for the existence of a self-oscillation regime in the first modulation zone, and MP proceeds to the stage of reorientation of the states of RE 4-2, 4-3, which ends at time t ₀₃ , when RE 4-3 switches to the identical position -A / 3 (Fig. . 4d). Coordinate Y _OUTPUT (t) reaches level -A (Fig. 4e), and MP goes into the second modulation zone, where in the intervals t ₁ , t ₂ (Fig. 4c) the speed of generation of the Y _and t scan signal (t) (Fig. 4b) ) is also determined by the difference or sum of the signals acting on the adder 1. In this case, the signal Y ₀ includes the constant component -A / 3 and the average value of the pulse flow Y _OUT (t) of the second modulation zone (Fig. 4e). The transition of MP from one modulation zone to another for small increments of the X _BX coordinate is accompanied by a transition of the system through characteristic points with a zero value of the frequency of the carrier oscillations (frequency-zero conjugation of the modulation zones).

The modulation and amplitude characteristics of MP for any i-th modulation zone are determined by the relations

- нормированное значение порога переключения b₁;

- нормированная величина входного сигнала MP, причем

; n - количество релейных элементов, причем n≥3 - нечетное число; Z_i=1, 2, 3… - порядковый номер модуляционной зоны; γ=t₁/(t₁+t₂) - скважность выходных импульсов MP; ±A - максимальная амплитуда выходного сигнала MP; T_И - постоянная времени интегратора 3.Where

- the normalized value of the switching threshold b ₁ ;

is the normalized value of the input signal MP, and

; n is the number of relay elements, and n≥3 is an odd number; Z _i = 1, 2, 3 ... - serial number of the modulation zone; γ = t ₁ / (t ₁ + t ₂ ) is the duty cycle of the output pulses MP; ± A - maximum amplitude of the output signal MP; T _And - the time constant of the integrator 3.

The launch of the pH 7-1 ... 7-3 is made by a signal of positive polarity (logical "1") from the output of the corresponding of the additional relay elements 6-1 ... 6-3 (Fig. 1). In relation to the situation considered, channel 5-3, 6-3, 7-3, 8-3, 9-3 is in working condition, since “1” is formed at the output of RE 6-3 (Fig. 4e, time interval t ≤t ₀₃ ), and channels 5-1, 6-1, 7-1, 8-1, 9-1 and 5-2, 6-2, 7-2, 8-2, 9-2 are turned off by voltage " 0 "from the outputs of the filters 5-1, 5-2, which is ensured by the negative sign of the average value of the pulse signal Y _P1 (t) (Fig. 4c) and the" negative "static state of the relay element 4-2 (Fig. 4d).

The situation with the input source can be changed. For example, if MP will work in the first modulation zone, and the voltage X _VX will be selected in sign negative and smaller in magnitude than -A / 3, then the relay element 4-1, being in the auto-oscillation mode, will generate pulses with an average value at the output positive sign. The signal from the output of the filter 5-1 will satisfy the condition Y ₀₁ > C ₂ , which will lead to the inclusion of the channel 5-1, 6-1, 7-1, 8-1, 9-1. In this case, only the cascade 5-2, 6-2, 7-2, 8-2, 9-2 will be in the off position.

Under the condition | -A / 3 | <| -X _BX | <| -A | there will be a situation in which all electric drives will be turned on, since (Y ₀₂ = Y ₀₃ = + A / 3)> C ₂ , and the average value of the output signal of the relay element 4-1 is also positive. As a result, the voltage Y ₀₁ > C _{2 is} generated at the output of the filter 5-1. In this case, additional relay elements 6-1 ... 6-3 will go to the logical "1" position, thereby launching the pH 7-1 ... 7-3.

Thus, in the General case, the number of enabled Executive control channels is determined by the sign and level of the input signal MP.

Consider the operation of the system taking into account the CLS 11-1 ... 11-3 (Fig. 1).

Each of the blocks 11-1 ... 11-3 is designed to diagnose the status of the corresponding relay elements 4-1 ... 4-3 MP. The principle of operation of blocks 11-1 ... 11-3 is identical, therefore, we consider the operation of the HLS 11-1.

The frequency divider 13 (Fig. 2a) is switched, for example, along the leading edge of the signal from the output of the relay element 4-1 (Fig. 2b, c) and generates an alternating pulse signal with an average value of zero (Fig. 2c). The proportional-differentiating link 14 transmits this variable signal with minimal distortion (Fig. 2 g) to the input of the demodulator 15, where it is converted to a constant voltage of logical "1" (Fig. 2e). Thus, the LSF pulse frequency at the output of the relay elements 4-1 ... 4-3 in the logical signal "1" (there is a frequency), or "0" (there is no frequency).

In the presence of a self-oscillating process in MP, i.e. when it is operational, at the output of one of the blocks 11-1 ... 11-3 there is always a signal "1", which is transmitted through the logic element "nOR" 12 to the emergency shutdown inputs of the pH 7-1 ... 7-3 (Fig. 1) and allows their inclusion. But with a certain type of malfunction in MP, the system should not turn on. One such malfunction is the failure of the MP power supply.

MP power is supplied from the source ± U _pit , but if this source is faulty, a situation is possible when + U _{pit is} present, and the voltage is -U _pit = 0. Then the self-oscillations in MP cease, since the relay elements 4-1 ... 4-3 are set to + A / n, which leads to the start of all control channels (5-1, 6-1, 7-1, 8-1, 9 -1), (5-2, 6-2, 7-2, 8-2, 9-2), (5-3, 6-3, 7-3, 8-3, 9-3). As a result, the pressure in the line 10 can increase sharply, which leads to its rupture.

This situation is eliminated using blocks 11-1 ... 11-3 and 12. In the absence of a self-oscillating mode in MP, blocks 11-1 ... 11-3 go to a static zero state even if they are powered from the same source as MP. Logic element 12 also switches to “0”. A signal of this level prohibits the supply of output signals of relay elements 6-1 ... 6-3 to the control input of the pH. Then the pH 7-1 ... 7-3 and actuators 8-1 ... 8-3 and 9-1 ... 9-3 are turned off, thereby preventing an accident on the line 10. If the situation + U _pit = 0, and the voltage -U _pit corresponds to the set value, the system also turns off. Firstly, the “OR” element 12 is de-energized, since the logic is powered by the source + U _pit , and secondly, in any situation, the loss of the self-oscillating mode in MP causes the appearance of the signal “0” at the output of blocks 11-1 ... 11-3 (Fig. 1).

Thus, the introduction of block 12 into the control system circuit increases its reliability in case of failures of the power supply MP.

Claims (1)

A control system for a group of electric drives with parallel control channels, containing a sequentially connected reference signal source, a multi-zone deployment transducer consisting of a first adder, an integrator, the output of which is connected to a group of n-th number of relay elements, n≥3 being an odd number, the outputs of which connected to the corresponding inputs of the second adder, the output of which is connected to the second input of the first adder, and n≥3 is an odd number of groups, each of which consists of a sequence but connected by a smoothing filter, an additional relay element, an asynchronous electric motor voltage regulator with an emergency shutdown input and a water pump, the output of which is connected to a common water main, characterized in that n≥3 is introduced into it - an odd number of frequency-logical-signal converters and logical element "nOR", and the inputs of the frequency-to-logic signal converters are connected to the output of the corresponding relay group of n≥3 relay elements, and the outputs of the frequency-to-logic converters “connected” to the corresponding inputs of the “OR” logic element, the output of which is connected to the emergency shutdown input of voltage regulators.

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