SU657561A1 - Power-diode dc drive - Google Patents

Description

The iteration of the known DC valve drives is made according to a scheme with slave current control 1 1 In this drive, the closed-loop speed control system contains a rotation frequency regulator and a current controller consisting of proportional-differential and integral regulators, and a compensation unit non-linearity of the discontinuous current mode, connected by the input to the current sensor, and the output to the current controller. Compensation for the nonlinearity of the discontinuous current mode in the electric drive is achieved due to the pulse-width switching of the structure and parameters of the current regulator. The disadvantage of the considered devices is that for fixing the flow of current through the valves it is necessary to use a current sensor with a high degree of sensitivity. This reduces the immunity of the control system and, consequently, the operational reliability of the electric drive. The closest technical solution to this invention is a DC electric drive 2 | containing a control unit, a reversible valve converter, an executive DC motor and a nonlinearity compensation module for a discontinuous current mode, connected to a summing element at the input of the pulse control link. Compensation of the non-linearity of the discontinuous current mode is realized by inputting a gate valve to the input, functionally dependent on the difference between the voltage at the input of the pulsed-phase control link of the gate converter and a voltage proportional to the motor's EMF. The aim of the invention is to increase the reliability and stability of the characteristics of an electric drive with a non-linearity compensating unit for a discontinuous current mode. This goal is achieved due to the fact that the compensation block contains a series-connected fixation link of the beginning of a dead-current pause consisting of a transformer, a resistor, a condensate and a rectifier, a threshold element with two inputs, a voltage time-varying link and a non-linear element, the primary winding the transformer of the fixation link of the beginning of the current-free pause through the resistor and the capacitor of this link under the Key to the motor core, the second input of the threshold element through the differentiating chain is connected to the second Exit-level pulse-phase control, and the beginning and end of the transformer secondary winding connected to a rectifier and through the keys to the common point of the control circuit. FIG. 1 shows a functional diagram of the proposed electric drive; in fig. 2 - curves of currents of voltage at the input of the pulsed-phase control link, explaining the principle of linearization of the characteristics of the electric drive; in fig. 3 - curves of current of rear and voltage Ug on the motor cortex in the mode of intermittent current; in fig. 4 shows voltage curves at the output of the compensation unit links in the proposed electric drive. The drive consists of a control unit; neither 1, the valve converter 2, the DC motor 3, block 4 to compensate for the nonlinearity of the characteristics of the electric drive in the bristled current mode. The control unit 1 contains a control element 5, the output of which is connected to the reverser 6 and logic circuit 7. The input of logic circuit 7 is connected to the current sensor 8 and one output to the reverser 6. The output of the reverser 6 is connected to one of the inputs of the summing element 9 and the output of summing element 9 is connected to the input of the pulse-phase control link 1O. The output of the link 10 through the switch 11, to which the second output of the logic circuit 7 is also connected, is connected to the control transitions of the valves of the converter 2. The non-linearity compensation block 4 of the discontinuous current mode contains a transformer 12, the primary winding of which through a resistor 13 and a capacitor 14 is connected to the motor core 3. The secondary winding of the transformer 12 through the transmitter 15 is connected to one of the inputs of the threshold element 16. The second input of the threshold element 16 through the differentiating link 17 is connected to the second output dy link pulse-1O faaovogo control of the control unit 1. The output of the threshold element 16 is connected to the input of the timebase unit voltage 18, the output of which through the nonlinear element 19 is connected to the input of the summing element block 9

heading .1 .. The secondary winding transfo) m.: 1 torra 1.2 Cheroz k.yuchn 20, 2.1 are connected to the common point of the circuit. The input circuits of the keypads 20, 21 are connected to the output of the logic circuit

7 control unit 1.

The drive is concerned as follows.

The control voltage from the link 5 through the reverser 6 is fed to the input of the summing element 9. The output voltage of the summing element 9 is fed to the input of the pulse control pulse 10. The pulse 1 from the link 10 through the switch 11 is fed to the control transitions of the thyristors one from the groups of the reversing converter 2 that feed the corona circuit of the direct current motor 3.

The output voltage of the control element 5 is also fed to the logic logic 7, the second input of which is supplied from the current sensor 8, the voltage at the output of the current sensor 8 does not depend on the direction of the current in the engine 3,

8, depending on the state of the logic circuit 7, the elements in the link 6 are switched in such a way that the voltage sign at the output of the link 6 changes only during the switching of the valve groups in the reversing converter 2. The switching of the groups in the valve converter 2 occurs depending on the sign of the voltage at the output of the control element 5 and the state of the valves of the switch-off group. When the sign of the output voltage of the control element 5 changes, the sign of the voltage at the output of the link 6 and at the input of the pulsed-phase control link 10 changes. Due to the change of the sign of the input voltage of the link 10, the angle of opening of the valves of the converter 2 becomes close to the maximum, and the current in the operating valve group is stopped. This changes the state of the logic circuit 7, which controls the switch 11, which distributes the control pulses from the link of the pulse-phase control 10 over the valve groups of the converter 2. The output circuits of the link

10 are disconnected from the control transitions of the de-energized valve group and connected to the control transitions of the group entering the operation. At the same time, the polarity of the voltage 1II at the output of the link 6 occurs, and after switching the valve groups of the converter 2, the voltage sign at the output of the reverser 6 does not depend on the sign of the voltage on the high voltage. the control element 5 and the direction of current in the engine bark 3. The voltage and g core of the engine 3 is fed to the input of the compensation unit 4.

The principle of compensating for the nonlinearity of characteristics in the proposed electric inode is that a nonlinear negative voltage is applied to the input of the pulse-4-loop control link.

feedback in terms of current-free pause in the power part of the valve converter. The introduction of a negative feedback signal in terms of the current-free pause is equivalent to the introduction of a positive feedback signal in terms of the current pulse duration, which follows from

relations

W,

,

(eleven

where S is the duration of the dead pause, in glad;

L. - current pulse duration, in glad;

m is the number of phases of the valve converter.

Approximate increment value

the voltage at the input of the pulsed-phase control link, necessary to compensate for the non-linearity of the characteristics of the valve actuator in the intermittent current mode of the motor core, is determined by the pz ratio

3

(f) f. (2)

40 where k - coefficient of proportionality, having the dimension in rad;

C is the coefficient depending on the parameters of the electric drive and the number of phases of the valve converter.

45This ratio based on (1) can be written as

(),., f (),

NW)

Where

P-G1-1 G1. . olfn,

(irj-k;) -iSs4-l-k we note that in real electric drives, U 0, k nf (.J)

-D

Claims (2)

also positive. Thus, compensation of nonlinear characteristics can be accomplished by introducing a DC voltage and phase voltage pulse-phase control link into the summing element at the input. At the same time, for intermittent-current currents that are close to the boundary-continuous one, this dependence is almost linear (at a small 6), while non-linearity is most pronounced at low currents in to the motor's re. In the proposed drive, the voltage change U voltage at the output of the compensation block 4 is determined by the ratio. K / u) tH {(s1), i where O is the circular frequency of the supply T. is the current time. In the absence of a current in the motor crust 3, the amplitude of the voltage 1G has a maximum value equal to and -k .4.il. Since in this case the base voltage must be equal to zero, on the basis of expression (3) the input voltage of summing element 9 must be applied to the bias voltage Iff, to compensate for Id. In a real electric drive, the voltage Jf to the input of summing element 9 the compensation is omitted in the pulsed phase control link 10. The instantaneous voltage U g at the output of the compensation block 4 at the time of the occurrence of the next control pulse of the converter transformer 2, so at the end of the current pause H, is determined from the expression (4) nr1 or1 amp; . 84.f (&), Napritsi G is fed to the input of summing element 9. At the same time, the total voltage U y determined by the dependence takes place at the input of the link of the pulse-phase control 10) FIG. Figure 2 shows the diagram of the Dy tJy voltages, the input of the 1O link at two values of the rear axle of the motor 3 for the voltage Uy, and the output of the elomolt yiipaiviHioirioro. With sTOMtJp Jp, FIG. 2, nfUieceuo is the linear reference voltage Ug, on the link of the pulse-phase control 10. The voltages Uy in FIG. 2, to simplify graphical constructions, are conventionally shown linear. As can be seen from ||) u. 2, the start of the voltage sweep Uy "at the end of the current pulse 3 lags behind the start of the voltage sweep at the end of the current pulse Rear. This leads to a decrease in the opening angle of the valves of the converter 2 by magnitude C and an increase in the voltage on the engine bark 3. Thus, a signal for compensating the nonlinearity of the drive characteristics in the discontinuous current region is inputted to the input of the phase-switching control link 10. The input circuit of the compensation unit 4 consists of the primary windings of the transformer 12, the resistor 13 and the capacitor 14 connected in series. In this case, the constant component Uq of the primary winding of the transformer 12 does not flow and the voltage of the primary winding of the transformer 12 corresponds to the ripple voltage on the core motor 3. These voltage pulsations are determined by a sinusoidal form of a 7keni mains supplying the converter valve 2 to the current of the motor core 3. Current curves of the motor 3, the voltage on the core vigatel UQ .napr and voltage U at the secondary winding of the transformer 12 in discontinuous current motor armature, shown in FIG. 3 a, b, c. FIG. 3 b also shows the emf level of the engine unit U, the voltage phase U is determined by the working group of the transducer valves 2, t. e. the direction of the rear current in the engine bark 3 and not, eh etc when this group operates both in rectifying and inverter modes. When the group operates in the inverter mode, only the voltage sign on the capacitor 14 changes. When the current direction changes in the engine bark 3, i.e., when switching the converter valve groups 2 ,. fa for voltage U, varies by 18 °. The parameters of the resistor 13 to the capacitor 14 are selected in such a way that an almost jump-like change in the polarity of the voltage jU is ensured at the time of the end of the current pulse c) 0 Pvigatol 3. tin FIG. 4 circuits per curve when one of the valve prototype-povatol 2 groups are operating. We assume that when one of the tpynn valves of the converter 2 is operating, the voltage UT shown in FIG. 4, is derived from the n-point (in Fig. 1, denoted by a dot) of the secondary winding of the transformer 12, the key 2O is open, the key 21, and a negative voltage 1Г-П (Fig. 4) c duration liit, corresponding to the negative voltage of pulsation Uj. i.e., the falling part of the current 3, the pulsanin U does not pass the positive voltage through the expander, because the secondary to the winding of the transformer 12 through the diode of the rectifier 15 is shunted by the open key 20, when the other group of converter 2 valves operates the voltage phase is changed to 180 ° C; in this case, the key 21 is open, the key 2O is locked. At the same time, the input voltage of the threshold element 16 is supplied with a negative voltage Uj (Fig. 4), corresponding to a positive voltage of pulsacin U, i.e. also a falling portion of the current LD. The negative voltage of the pulsation does not pass through the rectifier, since the secondary winding of the transformer 12 is shunted by the public key 21 of the rectifier 15 diode. The keys 20 and 21 are controlled by the logic circuit 7 of the control unit 1. Thus, the input of the threshold element 16, voltage Uj is applied, the papry of which does not depend on the phase voltage Lf, i.e. the current voltage in the engine bark 3, and the end of the voltage pulse at the input of the threshold element 16 is determined by the end of the current pulse Ld. The second input of the threshold element 16 through the differentiator link 17 is pulsed from the pulsed-phase control link 1O. As a result, the output voltage U (Fig. 4) of the threshold element 16 consists of two pulses: a narrow pulse corresponding to the beginning of the formation of the control signal in the 1O link, and a pulse determined by the voltage and j. The output voltage U of the threshold element 16 is fed to the input of the time sweep link 18. The time of the time sweep of the load 18 can be performed, HanfUfMop, in line with the linear variation of the first cyclic output voltage Up {fig, 4) The voltage Up becomes equal to zero when a pulse is applied from link 16. In the absence of current in the engine bark 3, the voltage does not flow to the input of the threshold element 16, and a voltage of a sawtooth shape with a constant amplitude takes place at the output of the time sweep link 18. If there is a current Ld in the interval of discreteness of the valve converter 2 at the output of the link 18, two voltage sweeps take place. The beginning of the first sweep is determined by the moment the pulse ends from the link 17, and the start of the second sweep coincides with the moment of the end of the current pulse 3. The output voltage of the time base of voltage 18 through the nonlinear element 19 is supplied in the form of negative feedback voltage to the input of the summing element 9 of the control unit 1. The instantaneous value of the voltage at the output of the nonlinear voltage 19 at the time (| is a magnitude depending on the current pause size.With an increase in the duration of the current pulse 3t, the instantaneous value of the negative feedback voltage on the dead time in NiOMeHT formulated and the control pulse of the valve feuber is reduced, which is equivalent to the introduction of positive feedback on the current pulse duration of the core. In the continuous current region E, there is no current pause, the end of one current pulse coincides with the instant of the next current pulse H, and the point where the voltage curve cuts off At the line of the reference voltage I, i.e., at the moment of opening the next valve of the converter 2, the voltage U. at the output of the link 19 is equal to zero. In this case, at the moment of intersection of the line Uy with the line UQ at the input of the link-pulse-phase control 10, the sum of the voltages Uy VU takes place. Thus, in the continuous current mode Gn, the nonlinear compensation block reaches the discontinuous current mode 4 does not affect the operation of the drive. In the discontinuous current mode J, the proposed electric drive has more stable gyu characteristics than the prototype. This is due to the fact that the output voltage U of compensation unit 4 is determined directly by the value of the dead time in the power circuit of valve converter 2, or by the duration of current pulses J, and does not depend on other parameters of the electric drive, for example, on the values of the initial impulse phase in the link 10. The impact on the characteristics of the electric drive of the compensation unit 4 in the continuous current 3 mode is excluded by the very principle of compensating for the nonlinearity of the discontinuous current mode. in the proposed drive. Since, in contrast to the prototype, compensation for non-linearity of electric drive characteristics in the discontinuous current mode is carried out without entering into the compensation unit information about the rotational frequency or the EMF of the engine, such an electric drive can be used both in the closed-loop frequency control system of the engine and in open-loop frequency of rotation electrically, yes, as well as in single-zone and in two-zone electric drives. These differences lead to an increase in the reliability and stability of the characteristics of the proposed electric drive in comparison with the prototype. Claims An DC gate motor comprising a control unit consisting of a control element whose output through a reverser and summing element is connected to the input of a pulsed-phase control link, and a logic circuit with a valve state sensor, one of whose outputs is connected to a reverser, and one of its inputs is connected to the output of a control element, a valve converter, whose input is connected via a switch to one of the outputs of the pulsed-phase control link, one of the converters The gateway is connected to the executive motor, and the second output is connected to the logic circuit through the valve state sensor, and the non-linearity compensation mode of the discontinuous current mode with two keys, the output of which is connected to the sum of the lean element, and the key inputs connected to the logic circuit characterized by that, in order to increase the reliability and stability of the characteristics of the electric drive, the compensation unit contains a series-connected fixation link for the start of the dead-time pause, consisting of a transformer, a resistor, condensation an ator and rectifier, a threshold element with two inputs, a time voltage sweep link, and a nonlinear element, the primary winding of the transformer of the fixation link at the beginning of the current-free pause through a resistor and capacitor of this link is connected to the motor core, the second input of the threshold element is connected via a differentiating chain to the second The input of the link is a phase-shift control, and the beginning and end of the secondary winding of the transformer are connected to the rectifier and, via keys, to a common point of the control circuit. Sources of information taken into account in the examination of l.Techibthe MitteiEun en LSU-l eefunken, 1971, t. 61, 7, p. 371-374. 2. Dynamics of DC valve electric drive, ed. A. D, Pozdeeva, M., Energie, 1975, p. 85, but u / t fus.l cat (Jn r lof. M tfLfU) t Rig.Z VH T N xhTxjv Up Fy