SU1833956A1 - Method for control of electric motor having valve transducer and apparatus for its realization - Google Patents

Description

The invention relates to electrical engineering and can be used to work out step-by-step program-setting actions when controlling the rotation speed of electric motors of various production mechanisms.

The purpose of the invention is to increase the main indicators of the quality of mining share their difference e (t), at the same time compare the measured value of the rotational speed with a given discrete program-setting action, form a discrete error value E (t) in terms of rotational speed, and control pulses are applied at a time determined by the established dependence. A device for implementing the method comprises a thyristor switch unit 1, an electric motor 2. Voltage and current sensors 3, 4, current-voltage converters 5, normalizing devices 6, summing amplifiers ?, functional converters 8, inverting amplifiers 9, linear switches 10, triggers 11, differentiating circuits 12, pulse shapers 13, made in the form of single-vibrators, software-setting unit 14, speed sensor 15, timing circuit 16, adder 17, controlled quantizer 18, clock speed controller 19, per stve which can be applied mains voltage, a frequency multiplier 20 and the relay member with adjustable hysteresis loop 21. 2 ri flu, 3 ill.

program-setting influences, namely, speed and accuracy by passive tuning (adaptation) of each control channel.

In FIG. 1 presents an example implementation of a device that implements the proposed method: in FIG. 2, 3 are timing diagrams explaining the operation of the claimed technical solution.

1833956 A1

A device for controlling an electric motor with a valve converter contains a block of thyristor switches 1, an electric motor 2, voltage and current sensors 3, 4, current-voltage converters 5, normalizing devices 6, summing amplifiers 7, functional converters 8, inverting amplifiers .9, linear keys 10, triggers 11, differentiating circuits 12, pulse shapers 13, made in the form of single-vibrators, software 14, speed sensor 15, timing circuit 16, adder 17, controlled quantizer l 18, the adjuster 15 clock frequency 19, which can be used as a mains voltage, a frequency multiplier 20 and a relay element with an adjustable hysteresis loop 21.

The device operates in the following manner: At the initial time, the moment of feeding, for example, a step-wise programming effect (ELV), the corresponding error signal E (t) will be generated at the output of the adder 17 (Fig. 2, a), providing the relay element 21 at the output signal generation: 'Upai (Fig. 2.6), which can be described by the following dependences, ire1 ~ sign E (t), with | E (t) | A1 for all t> 0: Ups (1-1), for E (t) G (-a1, a1) for all t> 0;

where + 1, for Ε (ΐ)> 0;

sign E (t) =

0, for E (t) = 0;

−1, for Ε (ΐ) <0;

using a current-voltage converter 5. The obtained values of voltages and currents through normalizing devices 6 to 20 go to the corresponding inputs of the summing amplifier 7, the output of which is a difference signal (see, Fig. 3, a).

2 * a1 is the value of the hysteresis zone, 25 Ia1 I = (l <2 / k1) U1 and -a1 = - (k2 / k1) U2, and moreover, k1 and k2 are the amplification factors of the corresponding amplifiers.

In addition, at the initial moment of applying the ELV, a reset signal will be generated at the output of the timing circuit 30, which will be fed to the corresponding input of the controlled quantizer 18 — its third input. This process is implemented by short-circuiting the keys of the quantizer, 35

MOS transistors.

which bypass the elements of its analog memory. In turn, the actuation of the relay element 21 will lead to the formation of trigger signals in each phase of the control channels along a chain of serially connected trigger 11, a differentiating circuit 12 and a pulse shaper 13. In this case, a short pulse at the output of a single-shot 13 (see Fig. 2, c) to switching the motor windings to a source of mains voltage. Hereinafter, to simplify the explanations, we will consider the process of generating control actions using the example of generating a control signal in one phase, 50 This process is valid for each phase separately.

The measured values of the phase currents la (Id, lc) are converted into voltage with

Eph (r) = (U _u (t) - υι (ΐ) Κφ (χ).

where Κφ (ΐ) is the gain of the adder 7, Uu (t) and Ui (t) are the normalized values of the measured values of (instantaneous) voltage and current, respectively. Each of which is obtained at the output of the corresponding normalizing device, implemented, for example, using a push-pull switching circuit

In addition, in the scheme of the normalizing unit, the transmission coefficient decreases starting from the smallest input signals, and not from a given nominal value, 40 as is the case in controlled limiters. This allows you to normalize the measured values of current and voltage in each phase based on the use of compressive displays of their amplitude values, namely, for harmonic:

Uu (t) = Au (t) ’sin ω t and Ui (t) = Ai (t) * sin (co t + Ф); providing Au (t) = Al (t) = A (t) for all t> 0, and this allows us to obtain a harmonic signal of the following form at the output of summing amplifier 7: e (t) = 2Αβίη (Φ / 2) x xcos (ct > t - Φ / 2), i.e. we obtain the normalized differences of the input values of currents and voltages of the corresponding phases (see Fig. 2.6).

The signal of the normalized difference e (t) is fed to the input of the functional converter 8, the operation of this block can be 5 described by the following relations

where h

m (t) = K / E (t) dt + n, i - 1 ΐι - ΐ (ι-1) is a multiple of the frequency of the mains voltage, while the multiplicity of this duration is set <1 / (Kp fc), the coefficient of multiplicity K _p can be chosen, for example, on the basis of using the counting theorem of continuous signals in a discrete representation> 2.

The process of forming the output sig. The functional converter is illustrated in FIG. 3, c. Moreover, on βθ of FIG. 3, d shows the moments of formation of pulse signals at the output of the pulse shaper 13. and in FIG. ZA, the corresponding open state region of the thyristors of switch 1 is shaded. 35

As can be seen from the above relations for the case dE (t) / dt = 0, by storing the previous state of the output value of the relay element Ep ₃ (i-1), for all E (t) Е (-а1, а1), where 12a1 k £ _T 49 is the value of the required (given) accuracy of the ELV testing, eliminating the possibility of losing information about the error signal, which explains the effect of increasing the accuracy of the ELV testing in the mode of processing small changes of E (t) without the need to calculate the derivative of the error signal. In this case, the conductivity angle of thyristors in each phase will be functionally related to the current values of the main indicators of the quality of working out program-setting actions.

The degree of functional connections can be separately set for each control channel both before switching on the control device 55 and directly during processing, for example, of each step of the program-setting actions. The above-described capabilities in many practically important cases of software control of electric drives, from the point of view of simplifying the tuning process and optimizing control modes (transient smoothness during start-up by reducing the intensity of electromagnetic processes), distinguish this method and device from known technical solutions.

Claims (2)

Claim 1. A method of controlling an electric motor with a valve converter, in which the frequency of rotation of the electric motor, phase currents and voltages are measured and control pulses are supplied to the corresponding keys of the converter in a certain sequence for connecting the electric motor to a power source, characterized in that, in order to improve the quality of regulation, they transform measured phase currents into voltages, normalize the measured voltages and voltages obtained as a result of the specified phase current conversion, s they instantiate their instantaneous values with each other and determine their difference e (t), at the same time compare the measured value of the motor speed with a given discrete program-setting action, form a discrete error value Ε (ΐ) in terms of speed, and control pulses are given at a time determined by the following relationship: + 1. for I e (r) I> m (t); Ф = <I \ i-1), for I e (t) I E I m (t) - n, m (t) I; Oh, for I e (t) I> m (t) - n; ti. where m (t) = K JE (t) d (t) + n is the proportional tti - 1 but-integral component of the error in rotation frequency, K and η are constant coefficients, (t - τι — 1) is the time interval that is a multiple of the frequency mains voltage changes. 2. A device for controlling an electric motor with a valve converter, comprising in each control channel a pulse shaper, phase current and voltage sensors, a clock frequency setter and a program-setting unit, the output of which is connected to one of the inputs of the adder, the second input of which is connected to the output of the speed sensor characterized in that, in order to improve the quality of regulation, a relay element with an adjustable hysteresis loop, a frequency multiplier, a controlled quantizer, a timing circuit, and in each the first control channel is a trigger, a summing amplifier, an inverting amplifier, a current-voltage converter '', two push-pull switching circuits for controlled keys made in the form of a series-connected input amplifier, controlled field-effect transistors and an output amplifier, the output of which is connected through a feedback amplifier and a rectifier with a gate of controlled field-effect transistors, and a three-position relay element, a linear key and a differentiating circuit, the output of which is connected to input pulse shaper house, the second input of the differentiating circuit is connected to the trigger output, one input of which is connected to the control input of the linear key and the output of the relay element with an adjustable hysteresis loop, and the second input is connected to the output of the clock frequency adjuster, the information input of the three-position relay element is connected to the output of the summing amplifier, the first input of which is connected to the output of the voltage sensor through the first push-pull circuit of the controlled keys, and the second input through the second two-circuit circuit To turn on the controlled keys and the current-voltage converter with the output of the current sensor, the output of the controlled quantizer is connected through an inverting amplifier to the first control input of the three-position relay element of each control channel, the second control inputs of which are combined and connected to the output of the controlled quantizer, the information input of which is combined with the input relay element with an adjustable hysteresis loop and connected to the output of the adder, input Reset controlled quantizer connected through remyazadayuschuyu circuit with the output of the driver unit and software, and control inputs connected to outputs of the frequency multiplier, whose input is connected to the output setpoint clock. .P ♦ αί m (t) -Qi to ' -------- - 1 ---- ‘4“ 'Zli - j - _t - II II _I'm from 1.1./:.1.- your FIG. Z FIG. 3 H ..... .p ..