SU1245455A1 - Apparatus for pulsed control of current of electric motors of electric vehicles - Google Patents

Description

The invention relates to transport, in particular, to devices for pulsed control of the current of electric motors of an electric rolling stock.

The purpose of the invention is to increase the reliability of the device.

FIG. 1 is a circuit diagram of a device for pulse control; in fig. 2 - time diagrams of voltages at the inputs and output of the modulator and currents at the outputs of the pulse shaper; in fig. 3 - timed10

(Kriya "FIG, 2). To the non-inverting input of the differential amplifier 9, a voltage Uj- (curve &) is applied, which is the algebraic sum of feedback voltage of the feedback signal (curve B) taken from current sensor 7, voltage D, and which is the threshold of sensitivity comparator 8 with respect to the voltage at the inverting input of the differential amplifier 9. The voltage value L U is given by the parameters of resistors 10 and 11. Since resistors 10 and 11 connect the output

Agram of currents on the control electro-15 differential amplifier 9 with its

dah thyristors pulse controller.

The device contains a thyristor controller made on two thyristors 2 and 3 and a switching capacitor 4 and connected in series with the traction motor 5 in the circuit of the power source 6. The motor circuit 5 of the motor 5 includes a current sensor 7 which is connected to one of the inputs of the comparator 8, made on the differential amplifier 9 and resistors 10 and 11. The other input of the comparator is connected to the current setting device 12. The comparator 8 in this device performs the functions of a pulse-width modulator. The output of the comparator 8 is connected to the inputs of the transducer 13 pulses, executed on two blocking generators, consisting of transistors 4 and 15, transformers 16 and 17, resistors 18 and 19, and capacitors 20 and 21.

The timing diagram (Fig. 2) shows: the voltage curve on the inverting input of amplifier 9, the voltage curve S on the resistor 10, the voltage curve 6 on the non-inverting input of amplifier 9, the voltage curve on the output of amplifier 9, the bottom of the output currents shaper 13 pulses.

The time diagram (Fig. 3) shows the curve r of the voltage at the output of the amplifier 9 and the curves f and e for the currents at the outputs of the pulse shaper 13.

The device works as follows.

Let from the current setting device 12 to the inverting input of the differential amplifier 9 receive the control voltage U

(Kriya "FIG, 2). To the non-inverting input of the differential amplifier 9, a voltage Uj- (curve &) is applied, which is the algebraic sum of feedback voltage of the feedback signal (curve B) taken from current sensor 7, voltage D, and which is the threshold of sensitivity comparator 8 with respect to the voltage at the inverting input of the differential amplifier 9. The voltage value L U is given by the parameters of resistors 10 and 11. Since resistors 10 and 11 connect the output

0

five

non-inverting input, differential amplifier 9 operates in trigger mode and voltage U | (curve) at the output of the comparator, and hence the voltage di, when the circuit is working moo--. They can have only two values fixed by amplitude and opposite in sign. Depending on the sign of the voltage U, only one of the blocking generators can operate. So, for example, if the voltage U is negative, then a negative bias is applied to the base of transistor 15 through a resistor 19, so this blocking generator generates pulses that open up the power thyristor 2. But the negative voltage is blocking for the blocking generator transistor

14, therefore, in this case, it is in standby mode. When the voltage comparator U | appears at the output of the comparator 8, for the same reasons, the blocking generator on the transistor goes into standby mode

15, and the blocking generator on the transistor 14 opens the switching thyristor 3 with its pulses. Moreover, when switching the switch, the corresponding blocking generator turns on

not immediately, but after some time T (fig.Z). This period of time is caused by a tem} that before the moment of switching the comparator B, the non-generating blocking generator is in the waiting mode and at the moment of switching on the plates of its capacitor, the effect of the blocking voltage U | Therefore, after changing the sign of the voltage U 5 on the code of the comparator 8, the capacitor is first discharged in the circuit before the tie of the blocking generator was working, and then, when the action

0

0

the blocking voltage is stopped, the blocking generator turns on and begins to generate periodic pulses. The presence of such pauses prevents the simultaneous supply of control pulses to thyristors 2 and 3. The minimum pause between the pulses of both blocking oscillators during switching is possible if at some time t simultaneously with the start of the pulse generation of the blocking oscillator, the comparator will switch 8, and a time delay begins before the start of another blocking generator. From the diagrams (Fig. 3) it can be seen that, with equal parameters of the pulses of both g-generators, the minimum pause is

 T - 2 t

where t

- the period of the generated oscillations; , tj is the pulse duration. In order for the proposed device to work reliably, this pause must always be longer than the time for the full charge of the commuting .. 4.

Thus, if at the initial moment of time t the voltage U coming from the current setting device 12 has a negative sign and exceeds the voltage in absolute value, then the output of the comparator 8 is set to a voltage and a positive sign. In doing so, it generates pulses of the blocking generator on the transistor 14 and the switching thyristor 3 is in the open state 1245455 h

then nii. The current supplied from the motor circuit 5 through the switching thyristor 3 charges the switching capacitor 4. At the time point C

the positive voltage U exceeds the voltage U, by the value of uU and the negative voltage U is set at the output of the differential amplifier 9. From this point in time, the blocking generator on the transistor 14 goes into standby mode, the supply of control pulses to the thyristor 3 stops and the pulsing generator on the transistor 15 starts to generate pulses. As a result, the power thyristor 2 opens and an increasing current causing an increase in the voltage on the sensor

7 current. At time t

condition U,

 Uy + 2 li, and the next moment U and + 2 li. This means a change in the sign; the voltage at the input of the differential amplifier 9, as a result of which the voltage Uf at the output of the comparator 8 changes the sign to a positive one. Turning on, the blocking generator on the transistor I4 switches on the co-fl iyt thyristor 3 and the controller 1 disconnects the motor circuit 5 from the power supply 6. The current in the engine 5 begins to decrease, causing a decrease in voltage and. With and - and -2-at time tj, the comparator 8 is switched again. Thus, a closed-loop relaxation system is obtained, in which the average value of the feedback voltage U c, a. therefore, the current of the motor 5 is adjusted in accordance with the value of the voltage and the control signal.

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Packs imp (. {LsVF & g

Editor A. Sabo

Compiled by N..Lyskov

Tehred N. Bonkalo Proofreader EYuirohman

Order 3949/10 Circulation 647 Subscription VNIKPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab ,, d.4 / 5

Production and printing company, Uzhgorod, Projecto st., 4

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Claims (1)

DEVICE FOR PULSE CONTROL OF THE CURRENT OF ELECTRIC MOTOR MOTOR MOTORS, containing a thyristor regulator and a current sensor connected to the inputs of the comparator, the output of which is connected to the inputs of pulse shapers made on transistors, capacitors, resistors and collector transformers, transistors in series with power supplies, characterized in that, in order to increase reliability, the emitters of transistors are combined and connected to the same th poles of the power supply and to one of the plates of the capacitor, which other electrode through the other windings of the transformers are connected to the bases of the respective transistors through resistors and a comparator output, the collectors of the transistors are connected to respective different poles of _a power supply can be used, and outputs the formation 1S rovateley are the third windings of transformers. Fig i 1 1245