RU68815U1 - STARTING DEVICE FOR ASYNCHRONOUS MOTOR WITH PHASE ROTOR - Google Patents

Abstract

The utility model relates to electrical engineering and can be used in AC electric drives based on an asynchronous electric motor with a phase rotor, induction resistors in each phase of the rotor and thyristors connected into a triangle, mainly for crane lifting and moving mechanisms that require lower speeds and natural mechanical speeds motor characteristics. The task is to create a multifunctional device in which it is possible to perform the functions of an electric motor starting device with access to a natural mechanical characteristic or controlling the speed of an electric motor. The problem is achieved in that in an electric drive with an asynchronous electric motor with a phase rotor, induction resistors in each phase of the rotor, thyristors connected in a triangle, and a control circuit that includes transformers connected to the voltage on the rotor rings, feedback forming unit, power supply , voltage setting block, block for resolving the output to the natural characteristic, integrator of the formation of the rate of output to the natural characteristic, by the number of phases of the rotor, blocks for selecting positive fields waves, sawtooth voltage generating units, adders and thyristor control units, a switch has been introduced, which, when the jumper is connected, connects to the voltage setting unit and by its connection changes the connections in the control circuit so that the device performs the function of outputting the motor to the natural mechanical characteristic when the jumper is disconnected the switch is disconnected, and the blocks in the control circuit are connected to perform the speed control function. 6 ill.

Description

The utility model relates to electrical engineering and can be used in AC electric drives based on an asynchronous electric motor with a phase rotor, mainly for crane hoisting and moving mechanisms, requiring lower speeds for choosing rope slack, landing speeds and for an exact stop, as well as working at the maximum possible speeds.

Known devices that provide speed control or access to the natural mechanical characteristic of the electric motor, providing the highest possible engine speed. The devices use inductive resistors (impedances), which are also called chokes, and electric drives with their use - induction chokes.

Known ballasts (article "Electrical systems and complexes." Interuniversity collection of scientific papers. Issue 12. Magnitogorsk 2006. Borisov AM, Drachev GI, Lyakh N.E., Nesterov AS, Shishkov A. N.) contains induction resistors in each phase of the rotor, thyristors, closing the outputs of the induction resistors connected to the rotor rings in a triangle, transformers, the primary windings of which are also connected to the rotor rings, feedback forming unit, positive half-wave voltage isolation blocks on the mouth rings pa blocks forming a sawtooth voltage, and adders summing blocks and control thyristors, the voltage control setting unit speed.

The device adopted as a prototype (patent for utility model RU 55229 u1, IPC Н025 5/00, IPC Н02Р 7/00, published July 27, 2006 bull. No. 21) contains induction resistors in each phase of the rotor, thyristors,

closing in a triangle the rotor rings at the end of starting the electric motor, a feedback voltage generation unit, the input of which is connected to the voltage on the rotor rings directly or through transformers, a work permit unit, sawtooth voltage shapers for each phase separately, nodes for extracting positive half-waves of voltage between the rotor rings, a power supply connected to the stator circuits of the electric motor or an independent source, an integration unit, a control pulse generation unit at the dash side, voltage setting unit.

An analysis of the descriptions of the presented devices shows that they have a large number of blocks and nodes with the same functional purpose and complex configuration.

Structurally, thyristors can be allocated to the power unit, and the entire control part can be located on the control panel (PU).

The claimed solution is based on the technical task of creating a universal device, which, using the same type of blocks and nodes, through simple switching can be used as a motor starting device with access to a natural mechanical characteristic or as a motor speed control device.

The specified technical problem is solved by the fact that the ballast of an induction motor with a phase rotor containing induction resistors in each phase of the rotor, thyristors connected in a triangle, transformers, the primary winding of each of which are connected to the rotor rings, and the secondary ones are connected to the input of the feedback forming unit and to the blocks for extracting positive half-waves of voltage, the output of each of which is connected to the second inputs of each block of the formation of a sawtooth voltage, the outputs are forming a sawtooth voltage connected to the first inputs of the control unit thyristors, the outputs of which are connected directly to the control electrodes of the thyristors of the respective phases are connected in delta

and connected directly to the rotor rings of the induction motor, the output of the feedback forming unit is connected to the first input of the resolution unit, to the first input of the sawtooth voltage generating unit of each phase, the power source, the input of which is connected to the stator circuits of the electric motor, and the output to the voltage setting unit, generating fixed voltages to the third input of the work permit unit, the output of which is connected to the third inputs of each sawtooth voltage generating unit and the first input integration unit, the first input of which is connected to the resolution unit and to the third inputs of the sawtooth voltage generating unit, the output of the integration unit is connected to the second inputs of each thyristor control unit, the second output of the voltage setting unit is connected to the fourth inputs of the sawtooth voltage forming unit, the third output of the voltage setting unit connected to the second input of the integration unit, the first output of the command unit is connected to the third inputs of each thyristor control unit, the second output One unit of the control unit is connected to the second input of the permission unit, according to the proposal, the ballast is equipped with a switch, the input of which through the jumper is connected to the voltage setting unit, and the output element of which is contactors, and adders, in which in each phase the first inputs are connected through the switch contact to the output feedback forming unit, and the second inputs to each sawtooth voltage generating unit, the adder outputs are connected to the first inputs of each dash control unit history.

In addition, the device may contain, in the above-described scheme, positive half-wave extraction blocks and sawtooth voltage generation blocks, adders, a resolution block, an integration unit and a switch together with contactors form a pulse extraction block, which is made in the form of a programmable controller with preservation of the functions of all these blocks.

The essence of the utility model is illustrated by the following figures.

Figure 1 - is a functional diagram of a ballasts that performs the functions of two devices, one of which provides speed control of the electric motor, and the other - the output of the electric motor to a natural mechanical characteristic.

Figure 2 is a functional diagram of the connection of the device for starting the electric motor with access to the natural mechanical characteristic.

Figure 3 - functional diagram of the connection device for controlling the speed of the electric motor.

Figure 4 is a graph of mechanical characteristics, while characteristic 1 is a natural mechanical characteristic, 2 is a characteristic with induction starting resistors in the rotor circuit, 3 shows a transition from a characteristic with induction resistors to a natural characteristic.

Figure 5 is a graph of mechanical characteristics, while characteristic 1 corresponds to a circuit with induction resistors short-circuited to a star, characteristic 2 corresponds to a reduced speed in the motor mode, characteristic 3 corresponds to a reduced speed in the anti-inclusion braking mode.

6 is a functional diagram of a ballast device implemented on a programmable PC controller.

The starting control device (Fig. 1) includes an asynchronous electric motor (M1) 1 with a phase rotor, a block of induction resistors (IR) 2, a block of power thyristors for the motor to reach its natural characteristic (BS VEH) 3, a block of power thyristors for regulating the speed of the electric motor (BS PC) 4, control panel output to the natural characteristic (PU VEX) 5, control panel speed control (PU PC) 6.

Power thyristor blocks 3 and 4 have the same circuit design, but can differ by thyristors, since when working on a natural characteristic, the rotor currents are less than when controlling speed.

The control panels 5 and 6 are exactly the same, but when jumper 7 is turned on, switching occurs in the panel diagram, which ensures the panel operates in the output mode for a natural characteristic, with the jumper disconnected - in the speed control mode. Therefore, figure 1 shows and further describes the composition of only the control panel 5.

On the control panel 5 are transformers 8, each with two secondary windings. The primary windings of the transformers are connected to the rings of the rotor of the electric motor. The first secondary windings of the transformers are connected to the outputs of the feedback block (BFOS) 9, and the second secondary windings of the transformers are connected to the inputs of the blocks for isolating the positive half-wave voltage of the transformers (BVPN) 10. The output of block 9 is connected to the first input of the block allowing operation of the output to the natural characteristic (BR) ) 11, to the first inputs of the blocks of sawtooth voltage formers (BPSF) 12 and through the opening contact 13.3 of the switch (K) 13 - to the inputs of the adders (∑) 14 of each phase separately. The outputs of the adders 14 are connected to the first inputs of the thyristor control units (BUT) 15, which supply unlocking pulses to the thyristor control electrodes of the power unit 3. The outputs of the positive half-wave extraction units 10 are connected to the second inputs of the units 12. The power supply (IP) 16 of the control panel is connected to stator circuits of the electric motor 1 or to an independent source. The output of the power source is connected to a voltage setting unit (BZN) 17 having 4 outputs. The voltage of the first output is connected to the input of the resolution block 11. In the resolution block, the voltage under consideration is compared with the voltage of the output of block 9 and, if the voltage from block 9 is less than the voltage from block 17 and there is an acceleration command to the maximum speed V _max coming from the command device (KA) 18 then a signal appears at the output of resolution block 11

permissions. This enable signal comes to the integration unit (BI) 18 and through the contact 13.2 of the switch (K) 13 to the third input of the units 12. The integration unit 19, having received the enable signal, integrates the voltage from the third output of the voltage setting unit 17 and through the contact 13.4 of the switch 13 the output of the integration unit is fed to the second inputs of the control units of the thyristors 15. The second output of the voltage setting unit 17 through terminal 13.1 of the switch 13 is connected to the fourth inputs of the sawtooth voltage generating units 12. The fourth output of the task unit is voltage 17 through a jumper 7 is connected to the input of the switch 13. The voltage setting the speed of the electric motor U _ss from the command device 18 through the contact 13.5 of the switch 13 is supplied to the third inputs of the thyristor control units 15. The above-described functional diagram is implemented on a programmable controller (PC), the functional diagram of which shown in Fig.6.

Figure 1 shows the use of the device in two functionalities, the control is carried out from one command device 18. The control device for controlling the rotor chain gives two signals: the command to reach the natural characteristic V _max at the extreme positions of the handle of the control device and the voltage of the motor speed reference U _ss , varying from the position of the handle of the command device from 0 to a maximum value of U _ssm . The value of U _scm takes place at extreme positions of the command device. At U _{scm, the} thyristors of the power unit for speed regulation 4 are open and the lower ends of the induction resistors are connected to the star. In this case, the signal V _max takes place and the output to the natural characteristic is provided by the panel 5 and the power unit 3.

The device is used only to achieve a natural characteristic (figure 2) or only to control the speed (figure 3). The diagrams shown in FIG. 2 and FIG. 3 are distinguished by the inclusion of power units, the presence of a jumper on the control panel and the connection of a command device

to the control panel. In figure 2 and figure 3 saved reference designations of the components adopted in figure 1.

Figure 4 shows that the apparatus without departing from the natural static torque characteristic at a steady M _CT mode the motor operates at a speed ω _std. When the device is turned on, it enters into operation at a transition speed ω _per specified by the voltage from the second output of the voltage setting unit to the fourth inputs of the sawtooth voltage generating units, and according to characteristic 3, the transition to the natural mechanical characteristic 1 is ensured, and in steady state it will work with the speed ω _ste .

Figure 5 shows the mechanical characteristics of the electric drive when the device plays the role of a speed controller, i.e. jumper "Output to the natural characteristic - Speed controller" is disabled. Characteristic 1 corresponds to the case of fully open thyristors (Fig. 3), i.e. with a closed thyristor star, which takes place only at U _ssm . Characteristic 2 corresponds to the operation of the electric drive at a reduced speed in the motor mode, and characteristic 3 corresponds to the operation of the engine in the anti-inclusion braking mode.

The principles of the formation of control pulses to the thyristors when the proposed device performs the output function of the natural mechanical characteristic and the speed control functions remain the same as with the known devices. A feature of the proposed device is that most of the blocks taken as a basis coincide with the prototype and an additional switching device is introduced, which is turned on / off by the jumper “Output to the natural characteristic - Speed controller”, when the jumper is on, the blocks are connected to perform the functions of reaching the natural characteristic, and when disabled - to perform speed control functions.

The proposed utility model provides:

- two completely different functions, which expands the scope of the device;

- in the warehouse for equipment redundancy it will be required to contain fewer devices, due to their greater functionality;

- maintenance staff will need to study one device instead of two.

- leads to a reduction in the range of equipment necessary for the implementation of electric drives based on induction motors and induction resistors and to a reduction in the number of redundant equipment for repair work.

The proposed universal ballast is successfully tested in the laboratory on an asynchronous electric motor with a power of 3.5 kW.

The utility model is intended for use in AC electric drives based on an asynchronous electric motor with a phase rotor and induction resistors in each phase of the rotor of crane lifting and moving mechanisms, drilling rigs and other industrial mechanisms.

Claims (2)

1. The starting control device of the asynchronous motor with a phase rotor, containing induction resistors in each phase of the rotor, thyristors connected in a triangle, transformers, the primary winding of each of which is connected to the rotor rings, and the secondary ones are connected to the input of the feedback forming unit and to the positive isolation blocks half-waves of voltage, the output of each of which is connected to the second inputs of each block sawtooth voltage formation, the outputs of the block sawtooth voltage generation under are connected to the first inputs of the thyristor control unit, the outputs of which are connected directly to the control electrodes of the thyristors of the corresponding phases connected in a triangle and connected directly to the rotor rings of the asynchronous electric motor, the output of the feedback forming unit is connected to the first input of the resolution unit, to the first input of the sawtooth voltage generating unit each phase, the power source, the input of which is connected to the stator circuits of the electric motor, and the output to the voltage setting unit, form fixing fixed voltages to the third input of the work permit unit, the output of which is connected to the third inputs of each sawtooth formation unit and the first input of the integration unit, the first input of which is connected to the permit unit and to the third inputs of the sawtooth formation unit, the output of the integration unit is connected to the second inputs each thyristor control unit, the second output of the voltage setting unit is connected to the fourth inputs of the sawtooth voltage generation unit, the third output is the voltage setting is connected to the second input of the integration unit, the first output of the control unit is connected to the third inputs of each thyristor control unit, the second output of the control unit is connected to the second input of the resolution unit, characterized in that the ballast is equipped with a switch, the input of which is connected to the task unit through a jumper voltage, and the output element of which is the contacts, and adders, in which in each phase the first inputs are connected through the switch contact to the output feedback forming unit, and the second inputs to each sawtooth voltage generating unit, the adder outputs are connected to the first inputs of each thyristor control unit. 2. The device according to claim 1, characterized in that the positive half-wave extraction blocks and the sawtooth voltage generation blocks, adders, a resolution block, an integration unit and a switch together with contactors form a pulse extraction block, which is made in the form of a programmable controller with preservation of the functions of all of the above blocks.