SU1317545A2 - Device for overheating protection of traction electric motors - Google Patents

Abstract

The invention relates to the field of electrical engineering and is intended for thermal protection of traction motors. The aim of the invention is to increase the reliability of operation of electric motors by preventing overheating of the insulation of the field winding. The excitation current signal from the output of the excitation current sensor 11 through the max-selector 9 is fed to quadrant 6. The output signal of the corrector comparator. 10 in this case defines etnn "raB Yu

Description

131

with the current signal of the excitation from the sensor 11 and switches to the state opposite to the thrust mode. The signal applied to the input of the adder 7. from the output of the comparator 10 changes the output of the adder 7 by an amount proportional to the difference in resistance of the core excitation winding for a certain temperature level. The corresponding inputs of multiplier 5 receive signals proportional to the square of the excitation current from quad 6 and the resistance of the heated excitation winding from the output of adder 7. Od1

The invention relates to electrical engineering, in particular, to devices for protecting the traction electric motors from overheating.

 The purpose of the invention is to improve the reliability of electric motors by overheating the insulation of the excitation winding.,

The drawing shows a block diagram of the proposed device.

The device contains IT threshold element 1, integrator 2, controlled attenuator 3, adder A, multiplication unit 5 (multiplier) 5 quad 6, cst mat 7, ambient temperature sensor 8, max selector 9, the input of which is connected to the first input house the comparator 10 and with the output of the sensor 11 of the excitation current of the traction electric motors, and the second input is connected via the maxiselector 12c with the sensors 13 of the main current of the electric motors. The second input of the comparator 10 is connected to the output of the max-selector 12, the output of the comparator 10 is connected to the corresponding input of the integrator 2 and to the inputs of the adders 4 and 7, and the second input of the adder 4 receives a signal from the cooling air flow sensor.

The device works as follows.

In the .t g mode, the excitation windings of the traction motor of a diesel locomotive are connected in series with the main winding. The current flowing through ob545

The Novremeino signal from the comparator 10 changes the output signal of the adder 4 by a constant value equal to the difference between the heat transfer from the excitation winding and the root winding, as a result of which the signals arriving at the integrator input are coherent with a constant time equal to the constant time of the winding motor excitation. When the signal about the overheating of the winding of an excitation setpoint exceeds a predetermined setpoint, threshold element 1 is triggered, which leads to an increase in the degree of cooling of the traction motors. 1 il.

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The coil is 5f, equal to the main current of the corresponding motor for the full field mode or it is a certain part of the main current in a weakened gyul when the excitation winding is shunted by the field weakening resistors. In this case, the proposed device determines the overheating of the core winding of the electric motor 51 J through which flows the greatest of the currents of parallel traction electric motors for which, with a detector 12, a maximal signal is transmitted from one of the sensors 13 of the main current (sensors ornogo current ustakazlivayuts in each traction motor circuit). Sensor 11 of the excitation current generates a signal only in the rheostatic deceleration mode, when all the windings of the excitation are interconnected and connected to a source of controlled voltage,. Therefore, the signal from the output of the excitation current sensor 1 1.: Arriving at the corresponding inputs of the max-selector 9 and the correction comparator Kc is zero. The nhrd kva., Drarator 6 enters the srggnal through maxiselector 9 from the output of maxiselector 12. At the output of the quadrant b, the signal is proportional to the square of the maximum of the main motor traction motors, I level of the output of the correction comparator 10

complies with the algorithm for calculating overheating of the root winding of the busiest motor and is fed to the corresponding inputs of the integrator 2, adders 7 and 4,

The multiplication unit 5 multiplies the signals of the quad 6 and the adder 7, its input signal is proportional to the copper loss of the core winding. Accounting for the ambient temperature is carried out using the adder 7, for which its inputs receive signals, one of which is proportional to overheating (from the output of the excitation current intensity. This signal goes to the corresponding inputs of the max selector 9 and the correction comparator 10. When the current B winds

grader 2), the other temperature is about f5 a signal proportional to the magnitude of the medium detected by the resistance thermometer sensor 8, which is located in the ventilation duct. The third input of the adder 7 receives a signal from the output of the comparator 10 and excitation excitation does not exceed the magnitude of the adder 7 so that the current is most loaded with its output that its output signal is proportional to the resistance of the core winding of the heated electric motor

 25

motor, through the selector 9 to the input of the quad 6 receives a signal corresponding to the highest crust current. The output signal of the corrective comparator 10 corresponds to the level at which the computing device calculates the magnitude of the overheating of the main winding of the traction motor according to the indicated thrust mode algorithm.

 R + R x s

about

where is r,

R

xs

Rn

6i g

resistance of the core winding in a heated state; resistance of the core of the coil at ambient temperature, resistance of the core winding at the ambient temperature, OS, temperature coefficient of copper resistance / overheating of the core winding compared to the ambient temperature. 40 The feedback signal of the integrator 2 is fed to its input via an attenuator 3, controlled by the voltage from the output of the adder 4, the value of which is related to the flow rate of the cooling air or the driver's controller position. The output voltage of the comparator JO applied to the other input of the adder 4 determines the output

electric motor, through Max-driver 9 to the input of the quad 6, the input signal corresponding to the highest core current. The output signal of the rectifier comparator 10 corresponds to the level at which the calculating device calculates the overheating profile of the core of the electric motor according to the thrust mode algorithm.

In the mode, when the excitation current exceeds the magnitude of the largest coupling current, the device operates as follows.

The excitation current signal from the output of the excitation current sensor 11 is cut by the max selector 9 to the square 6, the output of which is proportional to the square of the magnitude of the excitation current. The output signal of the correction comparator 10 in this case is determined by the signal for the excitation from the sensor 11 and the transition to the state opposite to the thrust mode. Such a change in the output of the compressor 10 converts the device for determining the overheating of the main winding of the traction motor to the alg last voltage, proportional to the 50 rhythm of calculating the superheating of the winding

specific heat emission Thus, from the output of the attenuator 3 to the input of the integrator 2, a signal is reversed according to the sign of losses in copper, proportional to the heat transfer of the core. The corresponding input of the integrator 2 is connected to the output of the corrective KONmapaTopa 10, which determines the integration of the input signals of the integrator.

torus with a time constant equal to the time constant of the main winding of a traction motor. Thus, in the traction mode, the device with the proposed structure calculates and controls the level of overheating of the core winding of the most loaded traction electric motor.

In the rheostatic braking mode, series-connected field windings are powered by an adjustable converter. An excitation current sensor 11 is located in the excitation winding circuit. At the output of the excitation current. This signal is fed to the corresponding inputs of the Max-selector 9 and the correction comparator 10. When the current B windings

a signal proportional to the magnitude of the excitation does not exceed the largest current of the most loaded

a signal proportional to the magnitude of the excitation does not exceed the largest current of the most loaded

motor, through the selector 9 to the input of the quad 6 receives a signal corresponding to the highest crust current. The output signal of the corrective comparator 10 corresponds to the level at which the computing device calculates the magnitude of the overheating of the main winding of the traction motor according to the indicated thrust mode algorithm.

In the mode when the excitation current exceeds the magnitude of the highest crust current, the device operates as follows.

The excitation current signal from the output of the excitation current sensor 11 through the max-selector 9 enters the quadrant 6, the output signal of which is proportional to the square of the magnitude of the excitation current. The output signal of the correction comparator 10 in this case is determined by the excitation current signal from the sensor 11 and switches to the state opposite to the thrust mode. Such a change in the output of the comparator 10 converts the device for determining the overheating of the main winding of the traction motor to the al-excitation of the traction motor. The signal given by aII to the input of the adder 7 from the output of the correction comparator 10 changes the output of the adder 7 by an amount proportional to the difference in resistance of the main field winding for a certain temperature level. Thus, at the output of the adder 7, we obtain a signal proportional to the resistance of the heated field winding.

R ... R,

Where

 G06

R

GOB

R

g

(uR

r i- & r.

resistance of the excitation winding in the heated state j

resistance of the core winding in a heated state;

the difference between the resistance value of the core winding and the winding of the exciter.

Signals proportional to the square of the excitation current of the electric motors from quadrant 6 and the resistance of the heated excitation winding, output from the adder 7, are output to the corresponding inputs of multiplier 5. The output signal of multiplier 5 is proportional to the loss in copper of the excitation winding.

At the same time, the output signal from the output of the corrective comparator changes the output signal of the adder 4 by a constant value, r.v., to the difference in heat transfer between the excitation winding and the crust winding at the same cooling air flow rate. Thus, from the output of the adder 4 to the corresponding input of the attenuator 3, a value is applied that is proportional to the specific heat transfer of the winding of the traction motor, and the electric motor - LV.

CD

about

where in

her

AT

but

specific heat transfer from the 4th day to the winding; specific heat emission of the crust winding; feB - the difference between the value

specific heat transfer of the excitation winding and the core winding for a certain consumption of cooling air;

In addition, the output signal acts on the input of the integrator 2 in such a way that the signals proportional to the copper losses of the motor excitation winding and the heat transfer of the excitation winding received at the input of the integrator 2 are integrated with a time constant equal to the time of the excitation winding electric motor. Changing the time constant of the integrator in a real electronic simulator for the

The tax integrator is connected by connecting an additional integrating capacitor, and for an integrator performed on digital elements, it is performed by changing the frequency of the output pulses of the master oscillator.

As a result of the changes made in the calculation algorithm, the signal formed at the output of integrator 2 is proportional to the magnitude of the superheat of the motor winding, which in this mode is the limiting element in relation to the superheat. When the excitation winding overheating signal exceeds the setpoint, threshold element 1 (trigger) is triggered, which leads to an increase in the degree of cooling of the traction motors.

The proposed device makes it possible to increase the reliability of protection of the traction electric motors from overheating, preventing overheating of the insulation of the excitation windings in excess of the allowable under heavy operating conditions.

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Claims (1)

Invention Formula Device to protect the traction motors from overheating by author. St. No. 824360, characterized in that, in order to increase the reliability of electric motors by preventing overheating of the excitation winding insulation, a second max selector, an excitation current sensor of the traction electric motors, a correcting comparator and a second adder, one input of which is designed, are additionally introduced into it for connection to the cooling air flow sensor, the second inlet is connected to the comparator outlet, to the third inlet of the first cus attor and to the second inlet of the integrator, and the outlet is connected to the control input of yuatora, maksiselektora first output connected to the first input of the comparator and a first input of the second maksiselektora, a second input coupled to an output of the current sensor vozbutkdeni the traction motor and the second input of the comparator, a second output connected to the input maksiselektora squarer. ,