RU2331131C1 - Group electromechanical switch - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: invention relates to group electromechanical switch with angular displacement of control element and is designed to switch over startup-and-break resistors stages in principle circuits of electric drive. Switch is provided with contacts actuated in radial direction by directed cams and elements mounted on common shaft such as contacts actuator in the form of multi-type set of profiled cam rings, device of angular shaft position arranged as contact-free sensor of absolute angular position with electrical outputs connected with electric motor control unit inputs. Motor shaft is linked with switch shaft via coupling and gearing. Anchor windings and induction windings are connected with control unit outputs being in the form of electronic programmable unit of angular shaft displacement connected to motor anchor and induction windings via electronic switchboard unit ensuring programmable cyclic startup, shutdown, electrical braking and reversing of electric motor in angular shaft position function.

EFFECT: improvement of accuracy, increment, stability and fast action of switchover control, improvement of reliability and extension of operational life while reducing switch weight, dimensions and manpower effort during manufacture process.

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Description

The invention relates to the field of traction electric drive, and more particularly to group electromechanical switches designed to switch the stages of brake resistors in the main circuits of the electric drive and acting as an actuating element of the automatic starting and braking of traction motors. The invention can be used in public transport, for example, in subway cars.

Known is a group electromechanical switch with angular movement of the control element, the contacts of which are driven by radially directed cams, comprising a device for actuating power contacts mounted on a common shaft in the form of a set of different type profiled cam washers and a device for determining the angular position of the shaft, the electrical outputs of which are connected to the inputs of the motor control device, the shaft of which is connected to the switch shaft through the clutch and gearbox, and the armature and excitation windings are connected to the outputs of the control device ("Guidelines for the operation of subway cars of models 81-717.5 and 81-714.5". M: Transport, 1993. S. 49-52).

In the aforementioned known switch, a contactor device EU1 is used as a device for determining the angular position of the shaft, the control contacts of which are also driven by radially directed profiled cams located on an additional part of the switch shaft. At the same time, the accuracy, discreteness and stability of determining the angular position of the switch shaft depend on the manufacturing accuracy and the degree of wear of the ES1 profiled cams, and the presence of a bulky, laborious in the manufacture of EU1 contactor device significantly increases the mass and dimensions of the switch, which worsens the dynamics (speed) and reduces the reliability switch.

A device for controlling an electric motor in said switch is made in the form of a set of relay-contactor elements switched by commands of contact devices EU1 in accordance with its scan (switching diagram). In this case, the sweep (switching diagram) of EC1 is uniquely determined by the selected profile of its cams and does not allow changing the parameters of the program cycle of the switch. In addition, the large number of contact elements in the motor control device further reduces the reliability of the switch.

A device for controlling an electric motor in a known switch connects the supply voltage to the armature and field windings directly, without intermediate switches (converters), which leads to sudden starts and braking of the electric motor, which are manifested in the form of shock loads on the mechanical elements of the switch, reducing the life of the switch.

In connection with the foregoing, the objective of the present invention is to solve these problems of the prior art.

To solve this problem, a group electromechanical switch with angular displacement of a control element is proposed, the contacts of which are driven by radially directed cams, containing a device for actuating contacts mounted on a common shaft in the form of a set of different type profiled cam washers and a device for determining the angular position of the shaft, electric the conclusions of which are connected to the inputs of the motor control device, the shaft of which is connected to the switch shaft A la through the clutch and gearbox, and the armature and field windings are connected to the outputs of the control device, characterized in that the device for determining the angular position of the shaft is made in the form of a non-contact absolute angle encoder, and the control device is in the form of an electronic programmable block for determining the ranges of angular displacement of the shaft connected to the windings of the armature and excitation of the electric motor through the block of electronic switches, providing software cyclic inclusion, shutdown, electric some braking and reversing the motor shaft in the angular position of function.

The technical result achieved by the set of essential features of the proposed technical solution consists in increasing the accuracy, discreteness, stability and speed of controlling the switching of stages of brake resistors in the main circuits of the electric drive, reducing the mass of rotating parts and eliminating contact elements by introducing a contactless absolute instead of a contactor device EU1 encoder of the angular position of the shaft, the possibility of flexible software changes in the parameters of the cycle the switch in relation to the type and operation modes of a particular vehicle and to increase the reliability and service life of the switch while reducing the weight, dimensions and complexity of its manufacture by introducing an electronic programmable unit for determining ranges of angular displacement of the shaft instead of the relay-contactor control device and connecting it to the windings anchors and excitations of the electric motor through an additionally introduced block of electronic switches.

The composition and principle of operation of the well-known group electromechanical switch is illustrated by the structural diagram shown in figure 1.

The composition and principle of operation of the proposed group electromechanical switch is illustrated by the structural diagram shown in figure 2.

The well-known group electromechanical switch (Fig. 1) contains a device 2 mounted on a common shaft 1 for actuating the power contacts 3 in the form of a set of heterogeneous profiled cam washers 4 and a contactor 5 for determining the angular position of the shaft, the control contacts of which 6 are radially actuated directional profiled cams 7 located on an additional part of the switch shaft 1. The outputs of the device 5 are connected to the inputs of the relay-contactor device 8 for controlling the electric motor 9, the shaft 10 of which is connected to the shaft 1 of the switch through the clutch 11 and the gearbox 12, and the armature windings 13 and excitation 14 are connected to the outputs of the control device 8.

Power contacts 3 of the electromechanical switch provide switching stages of brake resistors in the main circuits 15 of the vehicle’s electric drive.

The proposed group electromechanical switch (figure 2) contains a device 2 mounted on a common shaft 1 for actuating the power contacts 3 in the form of a set of heterogeneous profiled cam washers 4 and a device 5 for determining the angular position of the shaft, made in the form of a contactless absolute angle position sensor.

The outputs of the device 5 are connected to the inputs of the device 8 for controlling the electric motor 9, while the device 8 is made in the form of an electronic programmable unit for determining the ranges of angular movement of the shaft 1.

The outputs of the device 8 are connected to the inputs of the block of electronic switches 16, the outputs of which are connected to the armature winding 13 and the field winding 14 of the motor 9, the shaft 10 of which is connected to the shaft 1 of the switch through the clutch 11 and the gearbox 12.

Power contacts 3 group electromechanical switch provide switching stages of brake resistors in the main circuits 15 of the vehicle’s electric drive.

The proposed group electromechanical switch operates as follows.

The absolute sensor 5, the input value of which is the angular position of the shaft 1 of the switch, generates at the output amplified voltages of high and low levels corresponding to the units and zeros of the digital code. The output signals of the sensor 5 in the form of a parallel or serial code corresponding to the angle of rotation of the shaft 1 are fed to the input of an electronic programmable block 8, which, in accordance with the program included in it, decodes the input signals of the angular position of the shaft 1 into the range of group switch positions that differ the control algorithm of the motor 9, leading to the rotation of the shaft 1 of the switch. So, for example, if the total number of positions per one revolution of the switch shaft is n with an angular distance between the positions of 360 ° / n, then in block 8 are identified: position 1, position n / 3, range of positions 1 ... n / 2, range positions n / 2 ... n. In addition, after the shaft 1 of the group switch arrives at position n, in block 8, the nth position is stored and this information is stored in RAM until the shaft 1 of the switch returns to its original first position.

Along with the signals from the sensor 5, the input signals of block 8 receive the “Coast”, “Run 1”, “Run 2”, “Run 3”, “Brake 1”, “Brake 2”, “Brake 3” signals from the corresponding controller positions the driver and signals proportional to the actual values of the currents in the circuits of the traction motors, from current sensors in the main circuits of the electric drive.

Analyzing a set of input mode signals from the driver’s controller, signals from current sensors and signals from the sensor 5 of the angular position of the shaft 1, an electronic programmable unit 8 at each moment of time generates the output control signals of the electric motor 9, which are input to the block 16 of electronic switches.

The block 16 of electronic switches is made in the form of a single-phase bridge transistor inverter, the diagonal of the bridge of which includes a winding 13 of the armature of the electric motor 9, and additional transistor and diode connected respectively in series and antiparallel to the excitation winding 14 of the electric motor 9. Moreover, depending on the combination of input signals , block 16 includes a transistor in the field winding circuit 14 and two of the four transistors of the bridge inverter, providing either rotation of the electric motor in one of two possible directions, or its rapid electrical braking.

In the initial state of the traction electric drive (“Coast” signal at the input of block 8), the groups of traction motors are connected in series, and the group electromechanical switch is in the first position, while its power contacts provide the structure of the main circuits 15 of the electric drive with the maximum resistance value of the starting resistors. When the driver’s controller is placed in the first running position (“Run 1” signal at the input of block 8), the current in the main circuit is limited by the maximum resistance of the starting resistors, the electric motor 9 does not rotate, the electromechanical switch remains in the first position. This limited current mode is used to smoothly pull off or maneuver the vehicle at low speed.

When the driver’s controller is placed in the second running position (“Run 2” signal at the input of block 8), block 8 compares the set current setpoint with the actual value of the currents in the traction motor circuits and, if the actual current value falls below the setpoint, generates such a combination of control output signals transistors of the block 16 of electronic switches, which provides rotation of the electric motor in the forward direction corresponding to the rotation of the group switch from the first to the n-th position. At the same time, at each next position, the switch, with its power contacts 3, outputs one next degree of starting resistors from the main circuit 15 of the electric drive, maintaining the average current value of the traction motors at the level of the specified current setting during acceleration of the vehicle. After the output of the next stage of the starting resistors, the current in the circuit of the traction motors increases and becomes higher than the set point, therefore, block 8 generates such a combination of the output control signals of the transistors of the block 16 of electronic switches that provides a short circuit of the winding 13 of the armature of the motor 9 and its rapid electrical braking. At the next decrease in current in the main circuit below the setpoint, the process of rotation of the group switch in positions from 1 to the n-th position continues.

After the shaft 1 of the group switch arrives at position n, the starting resistances are completely output, while block 8 remembers the nth position in the main memory, issues a command to switch the groups of traction motors from the serial connection to the parallel one with the input starting resistors, and generates such a combination of transistor control signals block 16 of electronic switches, which provides rotation of the electric motor 9 in the opposite direction, corresponding to the rotation of the group switch from the n-th to the first p ozition. At the same time, similar to the previous one, the group switch produces alternately (to mitigate the traction shocks when moving from position to position) the output from the parallel circuits of the traction motors of the stages of the starting resistors while maintaining the current settings of the traction motors using the same power contact elements as with the serial connecting traction motors. This can significantly reduce the number of positions of the group switch while maintaining the required number of stages of the starting resistors.

If the driver’s controller is installed in the second running position, then after shaft 1 of the group switch arrives at the n / 3 position in the opposite direction of rotation, block 8 issues a command to return the group switch to the first position, and shaft 1 of the group switch is chronometrically (that is, locked on each position) on the shortest path returns to its original state. At this, the rheostatic start mode is completed, and further acceleration of the vehicle can occur only by automatically characterizing the full field without maintaining the specified armature current setting of the traction motors.

When the driver’s controller is placed in the third running position (“Stroke 3” signal at the input of block 8) after the rheostatic start is completed when the traction motors are connected in parallel to n / 3 positions of the group switch, block 8 issues a command to turn on the drive current regulators of the traction motors, which as the vehicle speed increases, they provide a smooth change in the attenuation coefficient of the field, maintaining the set value of the armature current of the traction motors corresponding to the current setting in position Turn 3 ". At the same time, the traction electric drive implements the ultimate traction automatic characteristic that provides the maximum dynamic performance of the vehicle at start-up.

Manual control of the rheostatic start-up when the traction motors are connected in series can be carried out by alternately installing the driver's controller from the position “Stroke 1” to the position “Stroke 2” and vice versa. In this case, after the driver’s controller is installed from the “Stroke 2” position to the “Stroke 1” position, the group switch shaft 1 is stopped and fixed at the last previous rheostat position, and when the driver’s controller is set back to the “Stroke 2” position, the shaft of the group switch 1 continues to subsequent rheostat positions. Such control can be used, for example, when the vehicle leaves the depot or shunting.

When the driver’s controller is in the brake position (signals “Brake 1”, “Brake 2” or “Brake 3” at the input of block 8), the operation of the group electromechanical switch occurs similarly to that described above for running modes. The difference lies in the fact that at all brake positions of the driver’s controller, in the high speed range, excitation controllers operate that support the corresponding armature current setting by gradually increasing the excitation current of the traction motors as the vehicle speed decreases. In the range of medium and low speeds after completion of the operation of the excitation controllers, an input “Switch operation permission” is received at the input of block 8, while block 8 generates such a combination of control output signals from block 16 that ensures that the motor 9 rotates in the forward direction corresponding to the rotation of the group switch from first to the nth position. In this case, at each next position, the switch, with its power contacts 3, outputs one next stage of brake resistors from the main circuit 15 of the electric drive, maintaining the average value of the current of the traction motors at the setpoint value corresponding to the given brake position of the driver’s controller during electric braking of the vehicle.

Similarly to the running mode, the positions “Brake 1” and “Brake 2” can be used for manual (bypass) control of rheostatic braking, and in the position “Brake 3” the traction electric drive implements the ultimate braking automatic characteristic that ensures maximum dynamic performance of the vehicle with electric braking.

After the shaft 1 of the group switch arrives at the n-th position, the electric braking efficiency begins to decrease, therefore, in the n-th position of the switch, block 8 gives a command to turn on the replacement pneumatic braking, which ensures efficient braking of the vehicle until it stops.

When the driver’s controller is set from any running or braking position to the neutral (zero) position (Run-out signal at the input of block 8), block 8 determines the actual angular position of the group switch shaft 1 and generates such a combination of transistor output signals of the electronic switch block 16 that provides the return shaft 1 of the group switch to its original first position on the shortest path. So, for example, if at the moment the “Coast” signal arrives at the input of block 8, the group switch is between the first and n / 2 positions, then block 8 forms a combination of control output signals corresponding to the rotation of the electric motor in the opposite direction, and the group switch from n / 2 to the first position. If at the moment the “Coast” signal arrives at the input of block 8, the group switch is between the n / 2 and n-th position, then block 8 generates a combination of control output signals corresponding to the forward rotation of the electric motor, and the group switch from n / 2 to the nth position.

This algorithm allows you to reduce the time interval when changing vehicle operating modes (switching from running to brake mode and vice versa).

The above-described control algorithm for a group electromechanical switch is typical, but not the only possible one. By changing the program recorded in the electronic programmable unit 8, it is possible to flexibly change the parameters of the group switch operation cycle, for example, change the boundaries of the controlled position ranges, provide, if necessary, fix the switch at each rheostat position, and create pulse-width control of the transistors of the electronic switch block. This expands the possibilities of using the proposed group electromechanical switch for other applications.

Claims (1)

A group electromechanical switch with angular movement of the control element, the contacts of which are driven by radially directed cams, containing a device for actuating contacts mounted on a common shaft in the form of a set of different type profiled cam washers and a device for determining the angular position of the shaft, the electrical outputs of which are connected to the inputs motor control devices, the shaft of which is connected to the switch shaft through the clutch and gearbox, and the armature windings and the excitation of which is connected to the outputs of the control device, characterized in that the device for determining the angular position of the shaft is made in the form of a contactless sensor of absolute angular position, and the control device is in the form of an electronic programmable block for determining the ranges of angular movement of the shaft connected to the armature windings and the excitation of the motor through block of electronic switches, providing software cyclic inclusion, shutdown, electric braking and reversing lektrodvigatelya in the angular position of the shaft functions.

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