RU2088432C1 - Device to control armature and field currents of traction motor - Google Patents

Abstract

FIELD: electric transport; electric rolling stocks with automatically controlled separate excitation of DC traction motors. SUBSTANCE: increased reliability, accuracy and quality of control are provided owing to introduction of lag filter, comparator unit and asymmetrical matching amplifier into proposed device and change of place of connection of scaling amplifier. Negative equivalent feedback is used in device although field current feedback is positive. Thanks to it required relationship between armature and field currents is maintained by regulating difference in currents and not only armature current as a function field current or field current as a function of armature current, as in known design versions. EFFECT: improved reliability and accuracy. 1 dwg

Description

 The invention relates to electric transport, namely to an electric rolling stock with automatically controlled independent excitation of DC traction motors and can be used to automatically regulate regenerative-rheostatic braking power in the field of limiting it to commutation of traction electric motors.

 A device for regulating the currents of the armature and excitation of the traction motor (ed. St. USSR N 192240, class B 60 L 15/20, 1967), containing the node selection of the maximum signal connected by inputs to the outputs of the first and second comparison units and the output through the amplifier to the input of the controlled excitation winding power supply, while the first comparison unit is connected by inputs to the master and the armature current sensor and the second comparison unit is connected by one input to the excitation current sensor and the other input through a static functional converter azovatel the sensor armature current.

 This device is designed to automatically control the traction force in the area of limitation according to the conditions for switching traction electric motors by adjusting the excitation current as a function of the armature current. However, in the case of using this device for automatic control of regenerative-rheostatic braking power, also in the field of limiting it by switching, it cannot guarantee the necessary reliability, acceptable accuracy, and sufficiently high quality of regulation. This is because in the regenerative-rheostatic braking mode, the derivatives of the armature and excitation currents have the same polarity. Therefore, the circuit for generating a signal for setting the excitation current in the device in question will be essentially positive feedback on the armature current.

 Closest to the proposed in its technical essence is a device for regulating the currents of the armature and excitation of the traction motor (Volokhov AB Control system of traction electric drive of a direct current electric locomotive with a static converter for powering the excitation windings of traction machines. Scientific works of MPEI, 1985, N 63, p. 96 - 102, Fig. 1), containing a series-connected adder, an armature current regulator and a controlled excitation coil power supply, an armature current sensor, the output of which is connected to the first input m of the adder, and a node for isolating the minimum signal, which is connected by the first input to the output of the armature current setter, the second input through a scaling amplifier to the output of the excitation current sensor, and the output to the second input of the adder.

 This device is intended for automatic regulation of regenerative-rheostatic braking force in the field of limiting it by switching traction electric motors by adjusting the armature current as a function of the excitation current. However, this device can guarantee the necessary reliability, acceptable accuracy and a sufficiently high quality of regulation, since the circuit for converting the signal of the field current sensor to the signal for limiting the set value of the armature current is also a positive feedback, however, in terms of the field current.

 The purpose of the invention is to increase the reliability, accuracy and quality of regulation.

 The goal is achieved by the fact that the device for regulating the armature currents and the excitation of the traction motor, containing a series-connected adder, an armature current regulator and a controlled excitation coil power supply, an armature current sensor whose output is connected to the first input of the adder, an armature current adjuster, a scaling amplifier and a sensor the excitation current, is equipped with an inertial filter, an asymmetric matching amplifier and a comparison unit, while the first and second inputs of the comparison unit, respectively, through inertia This filter and the scaling amplifier are connected to the outputs of the excitation current sensor and the armature current setter, respectively, and the output through the unbalanced matching amplifier is connected to the second input of the adder, the third input of which is connected to the output of the armature current setter.

 An inertial filter is included in the device to ensure the phase equality of the signals supplied to the first and second inputs of the adder.

 The comparison unit is introduced into the device for isolating a signal proportional to the deviation of the armature currents and excitation from their desired ratio. This desired ratio between the currents is amplified by the gain of the scaling amplifier.

 An asymmetrical matching amplifier is designed, firstly, to isolate and amplify the input signal of only one negative polarity. Secondly, to match the gain of the circuit forming the correction signal supplied to the second input of the adder, with the transmission coefficient of the circuit of the original signal for setting the armature current supplied to the third input of the adder.

 The introduction of the listed additional blocks into the device made it possible to use the output signal of the excitation current sensor as a reference signal for generating the correction signal of the initial signal for setting the armature current, while in known devices the output signal of the excitation current sensor is used as an additional positive feedback signal. Due to this, in the proposed device, an increase in reliability, accuracy and quality of regulation is achieved.

 The drawing shows a functional block diagram of a device for regulating the currents of the armature and excitation of the traction motor.

 A device for regulating the armature currents and the excitation of the traction motor contains a series-connected adder 1, an armature current regulator 2 and a controlled power supply 3 of the excitation winding of the traction motor 4, an armature current sensor 5, the output of which is connected to the first input of the adder 1, an armature current adjuster 6, scaling an amplifier 7, an excitation current sensor 8, an inertial filter 9, an asymmetric matching amplifier 10 and a comparison unit 11, the first and second inputs of the comparison unit 11, respectively, through inertia th filter 9 and scaling amplifier 7 are connected respectively to the outputs of the current sensor 8 and the excitation of the armature current set point 6 and output through an unbalanced matching amplifier 10 is connected to the second input of the adder 1, the third input of which is connected to the output 6 of the armature current set point.

 A device for regulating the currents of the armature and excitation of the traction motor works as follows.

 If the initial state of the device corresponds to the stabilization mode of the armature current at a value set using the armature current adjuster 6, then the output signals of the unbalanced matching amplifier 10 and adder 1 are equal to zero.

 With an increase in the signal for setting the armature current, a positive mismatch signal appears at the output of the adder 1, since the output signal of the armature current setter 6 supplied to the third input of the adder 1 becomes larger than the signal arriving at its first inverting input from the output of the armature current sensor 5. From the output of the adder 1, the error signal is fed to the input of the armature current controller 2, which is astatic and forms a control action. The output signal of the armature current controller 2 is supplied to the input of a controlled power supply 3, which changes the supply voltage of the field winding of the traction motor 4 in such a way that the armature current and, accordingly, the output signal of the armature current sensor 5 will monitor the change in the output signal of the armature current generator 6.

 But as soon as the output signal of the armature current generator 6 coming through the scaling amplifier 7 to the second input of the comparison unit 11 becomes larger in absolute value than the signal arriving at its first input through the inertial filter 9 from the output of the excitation current sensor 8, then at the output of the block 11 comparison shows a negative error signal. This mismatch signal through an asymmetric matching amplifier 10, in which it is amplified, is fed to the second input of the adder 1 and compensates for the positive mismatch signal between the signals arriving at its first and third inputs from the outputs of the sensor 5 and the armature current setter 6, respectively. As a result, the output signal of the adder 1 becomes equal to zero and the growth of the armature current stops.

 When the signal for setting the armature current is reduced so that the output signal of the comparison unit 11 becomes positive, the unbalanced matching amplifier 10 cuts off this signal and the device proceeds to stabilize the armature current at the value set using the armature current adjuster 6.

 Note that the description of the proposed technical solution is focused on the hardware implementation of the device. But its essence will not change if the device is implemented programmatically on a microprocessor base.

 In addition, the essence of the proposed technical solution will not change even when the device contains an internal circuit for regulating the excitation current with a slave current regulator for the armature current regulator. Or when the comparison unit is connected with the second input directly to the output of the armature current setter, and the first input through a series-connected scaling amplifier and inertial filter to the output of the excitation current sensor.

 Thus, the introduction of an inertial filter, a comparison unit and an asymmetric matching amplifier into the device increases the reliability, accuracy and quality of regulation.

Claims (1)

 A device for regulating the armature currents and the excitation of the traction electric motor, comprising a series-connected adder, an armature current regulator and a controlled excitation coil power supply, an armature current sensor, the output of which is connected to the first input of the adder, an armature current adjuster, a scaling amplifier and an excitation current sensor, characterized in that it is equipped with an inertial filter, an asymmetric matching amplifier and a comparison unit, while the first and second inputs of the comparison unit, respectively, through inertia This filter and the scaling amplifier are connected to the outputs of the excitation current sensor and the armature current setter, respectively, and the output through the unbalanced matching amplifier is connected to the second input of the adder, the third input of which is connected to the output of the armature current setter.