RU2662233C1 - Induction electrical machine - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the field of electrical engineering and can be used in synchronous reactive electric motors and generators used in transmissions of self-propelled machines for various purposes. Induction electric machine contains an uncoated rotor, the gear magnetic circuit of which is fixed to the shaft with bearings, and a stator with phase windings made in the form of lumped coils placed on the teeth of the stator magnetic core in its slots. Phase windings are connected to a converter realized on the basis of symmetrical bridge or half-bridge transistor modules, and are connected in a triangle, a polygon or a star through thyristors connected in series to these windings, or pairwise combined through these thyristors. Electric machine can be made without an excitation winding and without permanent magnets in the stator, as well as with the excitation winding and/or with permanent magnets in the stator. Thyristors can be three-lead or two-lead, conductive current in one or two directions. They are located, in particular, inside the enclosure of the electrical machine near the front parts of the coils of its phase windings.

EFFECT: technical result is increased efficiency and reduced torque ripple of an inductor electric machine.

4 cl, 6 dwg

Description

The invention relates to the field of electrical engineering, in particular to synchronous jet electric motors and generators used in electromechanical transmissions of automobiles, road-building machines, tractors, agricultural machines, all-terrain vehicles and other tracked and wheeled self-propelled vehicles.

Known N-phase valve-induction motor containing a gearless non-winding rotor and a stator with an explicit pole core and an N-phase winding, which is made in the form of gear coils and connected to an electronic converter, consisting of N phase winding switches, each of which is implemented according to the asymmetric circuit transistor bridge (US 615079, Н02Р 1/46, 11.21.2000; RU 2089991, H02K 19/10, 09/10/1997; Kuznetsov V.A., Kuzmichev V.A. Induction-induction motors. - M.: Publishing House MPEI, 2003).

The use of switches implemented in an asymmetric bridge circuit in the converter increases the total power and price of these converters by about two times compared with symmetric bridge converters (inverters), which are widely used to control asynchronous and valve motors. The implementation of asymmetric bridge circuits also necessitates the use of two types of transistor modules (modules in which transistor collectors are connected to the diode anodes, and modules in which transistor emitters are connected to the diode cathodes), which increases the range of components needed to implement the converters and worsens their maintainability.

Another drawback of these valve-induction motors, in comparison with asynchronous and valve motors having three winding leads, is the large number of conclusions (6 conclusions for a three-phase valve-induction motor, 8 conclusions for a four-phase, etc.).

Closest to the present invention is an induction electric machine comprising a non-winding explicit pole rotor and an explicit pole stator with lumped coils located on its teeth and forming phase windings that are connected in a triangle through diodes connected to these windings in series with each other. Phase windings are connected to an electronic power converter based on symmetrical half-bridge or bridge transistor modules (US 5703457, Н02Р 7/00, 12/30/1997; RU 2279173, H02K 19/36, Н02Р 6/16, 06/27/2006; RU 2352048, H02K 19/06, H02K 19/10, 04/10/2009; RU 2605957, B60L 11/02, B60W 10/08, B60K 17/12, H02P 8/00, 01/10/2017).

The disadvantage of this technical solution is the presence in the electric machine of a stray closed loop, which is formed by series-connected diodes and phase windings. The currents flowing along this circuit lead to an increase in losses in the phase windings (in copper) and in the magnetic circuits of the rotor and stator and, accordingly, to a decrease in the efficiency of the electric machine.

When the electric machine is operating in electric motor mode, the currents of the parasitic circuit create a braking torque, and when operating in generator mode, they generate torque, which leads to an additional deterioration in the efficiency, as well as to an increase in the pulsation of the torque of the electric machine.

The problem solved by the invention is to increase the efficiency of the induction electric machine while reducing the ripple of its torque.

In an induction electric machine containing a windingless rotor, a gear magnetic circuit of which is mounted on a shaft with bearings, and a stator with phase windings, which are made in the form of lumped coils placed on the teeth of the stator magnetic circuit in its grooves, and connected to a converter based on symmetrical bridges or half-bridge transistor modules, the specified technical result is achieved due to the fact that the phase windings through thyristors connected in series in these windings are connected to a triangle, or a polygon, or a star, or in pairs are combined through oppositely connected thyristors.

Implementation of the distinguishing feature of the invention is the use of thyristors connected in series in phase windings, which allows to prevent stray currents along the closed circuits of these windings, which are formed when they are connected to each other in order to enable the electric machine to work together with a bridge converter. This leads to a decrease in losses in the phase windings (in copper) and in the magnetic circuits of the rotor and stator, and also prevents the occurrence of spurious braking and torque during operation of the electric machine, respectively, in the mode of an electric motor or generator. Therefore, the implementation of this distinguishing feature of the invention leads to increased efficiency and reduced ripple torque of the induction electric machine.

In FIG. 1 shows a simplified diagram of a three-phase induction electric machine with a bridge converter made on bipolar transistors or transistor modules. In FIG. 2 and FIG. 3 shows possible embodiments of a six-phase electric machine operating in conjunction with a three-phase bridge converter, in which the phase windings are connected in a star and delta circuit. In FIG. 4 is a variant of a four-phase electric machine working in conjunction with two bridge converters. In FIG. 5 and FIG. 6 shows time diagrams of currents in the windings of a three-phase electric machine (Fig. 1), explaining the principle of its operation.

In this case, by an induction electric machine is meant a synchronous electric machine (electric motor and / or generator), in which the armature and field windings are located on the stator (can be combined), and the windingless rotor has a number of teeth-protrusions located around the circumference.

Such electric machines that do not have a field winding and permanent magnets in the stator are referred to in the Russian literature as valve-inductor, valve-reactive, valve induction jet engines and generators (WFD, VID, VIRD, VRG, TIG), and in English literature as electric motors or alternating magnetic resistance generators: Switched Reluctance Motor (SRM) or Switched Reluctance Generator (SRG).

The inductor electric machine can also be made with permanent magnets in the stator without a field winding - "Flux Switching Motor" (FSPM), with a field winding and permanent magnets in the stator (with hybrid excitation) - "Hybrid excitation flux switching motor" (HEFSM), Hybryd Excitation Flux Switching Synchronous Machine (HEFSSM), etc.

It contains a rotor 1 and a stator with phase windings 2 (Fig. 1-4, phases A, B, C, D, E and F), made in the form of concentrated coils placed on the teeth of the stator magnetic circuit in its grooves. Coils related to one phase can be connected to each other in series and / or in parallel.

The stator may comprise a separate field winding (s) and / or permanent magnets. These magnets can be located, in particular, in the middle part of each tooth of the stator magnetic circuit.

The rotor 1 is made without winding and contains a position sensor 3 thereof, made in particular in the form of a magnetic or optical encoder. A toothed magnetic circuit of the rotor is mounted on its shaft 4 with bearings installed in the bearing shields.

Magnetic cores (cores) of the stator and rotor 1 are drawn from insulated sheets of electrical steel.

Phase windings 2 are connected to a power electronic converter 5, made on the basis of symmetrical bridge or half-bridge transistor modules.

Transistor modules can be implemented on bipolar transistors (BT), on insulated gate bipolar transistors (IGBTs), referred to in English terminology - "Insulated Gate Bipolar Transistor" (IGBT), or on insulated gate field effect transistors, which can be used to indicate which the terms MOS (metal-oxide-semiconductor) or MIS (metal-dielectric-semiconductor), and in English terminology - MOS, MOSFET or MOSFET (from the abbreviation: “Metal-Oxide-Semiconductor” (metal-oxide-semiconductor) and “ Field-Effect-Transistors "(tra ican, controlled by an electric field) and their transcription.

In FIG. 1 as an example, a three-phase bridge converter made on bipolar transistors with antiparallel diodes is shown. It can be implemented in the form of one three-phase bridge transistor module or three transistor modules, implemented according to the scheme of a symmetrical half-bridge.

By a transistor module in this invention is meant any device implemented in a half-bridge, single-phase bridge or multiphase bridge circuit and made both in the form of a structurally complete module in a separate case, and on the basis of separate (discrete) transistors and diodes, for example, in TO-type cases -220, TO-247, TO-3P, etc.

Phase windings 2 through successively connected thyristors 6 are connected into a triangle (Fig. 1, Fig. 2), a polygon, a star (Fig. 3) or are paired through these thyristors (Fig. 4).

In this case, a thyristor means a semiconductor device with three or more pn junctions, considered as an electronic switch (key) having two stable states. A thyristor can have three electrical outputs - an anode, a cathode and a control electrode. It is also possible to use double-output thyristors - dynistors, in which the transition to the state of high conductivity occurs at times when the voltage between its anode and cathode exceeds the opening voltage.

In the proposed device, it is possible to use thyristors that conduct current both in one direction (for example, trinistors), and in two directions - triacs (symmetric triode thyristors or triacs (from the English. TRIAC - "Triode for alternating current")), symmetric dinistors and etc.

It is preferable to use three-output thyristors that conduct current in one direction, as well as their placement inside the body of the electric machine near the frontal parts of the coils, outside the electric machine on its body or on the shield, which leads to a reduction in the total length of electrical connections and, consequently, to increase Efficiency, power and torque of an electric machine.

Converter 5 operates under the control of controller 7, implemented on the basis of a microcontroller of general use or a digital signal processor, specially designed to control electric machines.

The controller 7 contains galvanically isolated drivers of the transistors that make up the transistor modules of the converter 5 and thyristors 6. These drivers generally contain amplifiers of gate currents (bases) of transistors, galvanically isolated power supplies of the secondary driver circuits, as well as analog and logic elements designed for the protection of transistors and thyristors from overheating and overloads of current and voltage, providing the necessary on / off speeds of transistors (transistor muzzle), diagnosis of their condition, etc. Thyristor drivers can be implemented based on trinistor or triac optocouplers.

The controller 7 also includes interface devices for receiving signals from the rotor position sensor 3, current sensors 8 in the phase windings 2, voltage sensors on these windings, temperature sensors of the phase windings, etc., as well as for exchanging information between the controller and external devices. This exchange is implemented using analog or digital signals on separate wires or on a digital multiplex communication line, for example, via the CAN bus (Controller Area Network). It is also possible to use wired interfaces like LIN (Local Interconnection Network), RS-485 (EIA / TIA standard), etc., as well as wireless interfaces like ZigBee (IEEE 802.15.4 standard), Wi-Fi (IEEE 802.11 standard) , Bluetooth (IEEE 802.15.1 standard), etc.

The converter 5, considered as a separate device or in conjunction with the controller 7, can be called a power electronic converter, inverter, power switch, electronic transistor switch, control unit of an electric machine, power controller, etc.

The electric power supply of the converter 5, controller 7 and the induction electric machine as a whole when it is operating in the electric motor mode is carried out via DC busbars + U, -U. On the same buses, energy is transferred to the load when the electric machine is in generator mode.

To smooth the ripple of the supply voltage of the electric motor and the output voltage of the generator, a capacitor 9, a group of parallel-connected capacitors or a battery are used.

When the induction electric machine is in electric motor mode, an electronic converter (power switch, inverter, etc.) 5 operating under the control of the controller 7 synchronously connects the phase windings 2 in turn with the position of the shaft 4 of the rotor 1, determined by the rotor 3 position sensor to a constant voltage source (to power buses) + U, -U. For this, the simultaneous inclusion of one upper and one lower transistors related to different half-bridges of the converter. At the same time, the controller 7 generates control pulses of the thyristor 6, which should be in a conducting state during operation of this phase. In the case of using two-output thyristors (dynistors), the voltage of their transition to the conducting state (switching voltage) is selected less than the output voltage of the converter 5 (i.e., less than the difference between the minimum voltage on the power buses + U, -U and the voltage drop across the transistors transducer), which leads to an automatic transition of the dynistors to a conducting state after turning on the transistors of the converter.

The current flowing through the windings of phase A, B, C, D, E or F creates a magnetic flux in the stator and rotor magnetic circuits. As a result of the mutual attraction of the teeth of the stator and the rotor, a torque occurs, which drives the shaft 4 of the induction electric machine.

After turning the shaft 4 of the rotor 1 by an angle corresponding to the number of phases and the number of pairs of poles of the electric machine, the controller 7 disconnects the transistors of the converter, supplying voltage to the working phase. The current in it begins to decline. Next, the controller 7 generates the switching signals of the transistors and the thyristor of the next phase. A current begins to flow through it. In this time interval, the current in the previous phase decreases to zero, which leads to the turn off of the thyristor 6 of this phase. Further, the processes are repeated, resulting in a continuous rotation of the shaft 4 of the rotor 1.

In addition to the described symmetrical switching of the phase windings 2, depending on the number of phases, the number of teeth of the rotor and stator, as well as the requirements for the pulsations of the torque of the electric machine, pairwise symmetric and asymmetric switching of its phase windings are also possible.

During the operation of each phase, pulsed (pulse-width, pulse-frequency, pulse-time, on-off, etc.) current regulation in its winding is carried out. The current measurement necessary for this regulation is carried out using current sensors 8.

After two transistors are switched off simultaneously in the converter 5, through which the voltage of the power buses is supplied to the winding of the working phase, the current of this winding begins to flow through the antiparallel diodes of the transistor modules. In this case, the polarity of the voltage on the phase winding changes to the opposite, and its value at the initial time is equal to the voltage on the power buses. This leads to a rapid decrease in current in the phase winding.

If only one transistor is turned off in the converter 5, then the current in the phase winding is closed through the second transistor and the antiparallel diode remaining turned on. In this case, the voltage across the phase winding is close to zero, which leads to a slow decrease in this current.

Accordingly, by regulating the on and off times of transistors in the converter 5, the current in the phase windings and, accordingly, the torque of the electric machine is regulated. In this case, when two transistors are turned on, a switching pulse of the corresponding thyristor 6 is simultaneously formed. This thyristor remains in the on state during the regulation of the current value in the phase winding.

The external control signal of the electric machine, which is received, in particular, via the CAN bus, can set, for example, the magnitude of the torque or rotational speed of the rotor.

In the first case, the controller 7 sets the amount of current in the phase windings 2, corresponding to a given value of torque. In the second case, the controller 7 determines the rotational speed of the rotor shaft using the rotor position sensor 3, compares the current value of this speed with a given one and performs pulse control of the current in the phase windings depending on their mismatch.

At the same time, the controller 7 provides protection for the converter 5 and phase windings 2 from emergency conditions - from overheating, over current, etc. At the same time, part of the protection functions can be implemented in hardware directly in the drivers of transistors and thyristors, and part of the functions can be implemented jointly by drivers and a microcontroller (software), on the basis of which controller 7 is implemented.

When the electric machine is operating in the generator mode with a rotating rotor 1, transistors of the transducer 5 transfer the generator excitation pulses to the phase windings by connecting + U, -U power bus voltage to these windings. The moments of connection of each phase winding and the duration of the time intervals during which this connection is made are determined by the controller 7 depending on the position and speed of rotation of the rotor, the magnitude (resistance) of the electrical load and the required value of the output voltage of the generator, which is set, in particular, by CAN bus. After the end of each excitation pulse, each phase goes into the generator mode and the current alternately from each phase winding 2 through the antiparallel diodes of the transistor modules, which perform the functions of a power rectifier, enters the busbars + U, -U and then to the load.

In FIG. 5 and FIG. 6 shows time diagrams of currents in the windings of a three-phase induction motor (Fig. 1). In FIG. 5 - in the case of installing diodes in series in the phase windings, in FIG. 6 - thyristors.

From these time diagrams it follows that replacing the diodes with thyristors eliminates the stray currents that occur in the phase windings before switching on the next phase. This leads to a decrease in losses in the windings and in the magnetic circuits of the stator and rotor by approximately 0.7 ... 3%. The exclusion of parasitic currents also allows you to exclude the corresponding braking moment of the electric machine when it is operating in electric motor mode and torque when working in generator mode. Thanks to this, an increase in efficiency and a decrease in the ripple of the torque of the electric machine are achieved.

For specialists in this field of technology it is clear that in addition to the described options for an induction electric machine, other options for its implementation are also possible based on the features set forth in the claims.

Claims (4)

1. An inductor electric machine containing a windingless rotor, a gear magnetic circuit of which is mounted on a shaft with bearings, and a stator with phase windings made in the form of concentrated coils placed on the teeth of the stator magnetic circuit in its grooves, the phase windings being connected to a converter made on the basis of symmetric bridge or half-bridge transistor modules, and through thyristors connected in series in these windings, connected to a triangle, or polygon, or star, or in pairs nen through these thyristors. 2. The induction electric machine according to claim 1, characterized in that it is made without a separate field winding and without permanent magnets in the stator, or without a separate field winding with permanent magnets in the stator, or with a separate field winding with permanent magnets in the stator, or with a separate field winding without permanent magnets in the stator. 3. The inductor electric machine according to claim 1, characterized in that the thyristors are made of three-pin or two-pin, conducting current in one or two directions. 4. The inductor electric machine according to claim 1, characterized in that the thyristors are located inside the body of the electric machine near the frontal parts of the coils, or on the outer surface of the housing, or on a bearing shield.

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