RU1791903C - Nonreversible d c electric machine with rectifier-mechanical commutator - Google Patents

Abstract

Use: to improve switching in electric machines. SUMMARY OF THE INVENTION: the machine contains a mechanical collector with conductive and insulating plates, two different-brushed groups of brushes in contact with them, a control circuit, in each group of brushes one of the contacts is offset along the track of the working surface of the collector relative to the second contact, and the control device is used as a switching device a removable semiconductor element, such as a transistor or a lockable thyristor. 3 ill.

Description

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The invention relates to electric machines, in particular to DC electric machines with additional devices for improving switching.

A known electric machine with a fan-mechanical commutator (VMC), comprising a mechanical collector and brush groups in contact with it, connected to a power source via controlled semiconductor elements. In the machine, switching is carried out without additional poles using capacitive electric energy storage devices.

A disadvantage of such a machine is its complexity.

Also known is an electric direct current machine with a VMC, comprising a mechanical collector with conductive and insulating plates in contact with

They are two different-polarity groups of brushes connected to the mains supply via switching devices and consisting of two contacts each, diodes and the control circuit shunting the main circuit.

According to the technical nature and the achieved result closest to the invention adopted for the prototype, there is a machine in which the set of switching elements used provides the functions of a commutator and a voltage regulator on the motor cortex in any direction of rotation. At the same time, there is a large group of non-reversible electric drives in which the same functions can be performed using fewer switching elements.

An object of the invention is to simplify an electric machine operating in a non-reversible mode.

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This goal is achieved by the fact that in each unipolar group of brushes the incoming contact is displaced along the working surface of the collector relative to the running one by a distance equal to half of the collector division, a fully controllable semiconductor incoming contact element is connected between the incoming contact of one of the brush groups and the mains terminal groups of brushes of opposite | yulnos are connected with the corresponding terminal of the power supply directly, between the run-down contacts of different-polished groups of brushes and the corresponding and terminals Mains included tiri- Store.

Unlike the prototype and other known devices, the proposed device contains only one fully controllable semiconductor element instead of two, providing the functions of a pulse voltage regulator and a current switch in sections of the core winding. The thyristors connected between the runaway contacts and the heterogeneous busbars of the power supply function as starters, which provide a short-term connection of the power supply to the core winding if one of the running contacts is on the insulating plate before starting the motor. In accordance with the indicated functional purpose, the starting thyristors have significantly lower installed power than the switching devices of the prototype.

In FIG. 1 (as an example) is a circuit diagram of a machine with an IUD (bipolar machine, wave winding, contains 9 enlarged sections. Excitation winding is not shown); in FIG. 2 is a block diagram of one embodiment of an engine control circuit with a VMC; in FIG. Figure 3 shows diagrams of the control signals that are supplied to the switching devices and current diagrams in these devices.

The machine contains a winding 1 located on the cortex, connected to a mechanical collector 2 with conductive 3-11 and insulating 12-20 plates, heteropolistic groups of brushes in contact with them, consisting of contacts 21-24 connected to the mains through switching devices 25 -27, core shunts, diodes 28, 29 and control circuits 30. The control circuit includes; a position sensor 31, pulse shapers 32, 33, an adder 34, a delay unit 35, a gate pulse amplifier 36, a gate pulse amplifier 37 and a trigger pulse block 38, which enables thyristors 26 and 27 to be switched on in the machine starting conditions. The position sensor (DP) of a discrete type, as in a valve motor, generates two sequences of pulses B1, B2 having a relative displacement of 180 electrical degrees. The number of pulses per revolution of the engine shaft in each sequence is equal to the number of collector conductive plates.

During operation of the machine, the sliding contacts move from left to right along the working surface of the collector (Fig. 1). In the position of the sliding contacts shown in FIG. 1, FIG. 3 and corresponding to the time ti, the core current flows from the sliding contact 21, through the plate 3, the core winding, the plate 8, contact 24,

0 through the reverse diode 28. Thyristors 25-27 are disabled. At time ti, a control pulse is generated in the channel B1 of the position sensor, which, passing through blocks 32,34,36, is converted into a trigger pulse Uo, which enables the locking thyristor 25 to turn on. After opening this thyristor, the voltage of the power supply is applied to the section of the coil winding associated with the plates

0 3, 4, in which the switching process begins. Assuming that the sliding contact 23, located on the insulating plate 12 at the time ti, starts to contact the conductive plate 4, the valve current

5 25 J25 flows along the contour; plus power source — 25-23-4-section -3-21-28-minus power source. After the passage of time Tk, the current of the diode 28 28 decreases to zero, the current of the valve 25 becomes equal to the current core (zs). AT

In section 0, connected to plates 3, 4, the current reversal process ends, and the core current flows along the circuit: plus source-25-23-4-winding-8-24-minus source.

5 At time point 2, when the sliding contacts move across the collector by half the width of the conductive plate or after the lag time Γ provided by block 35 expires, a negative polarity signal Us appears at the output of the blocking pulse amplifier 37 (in Fig. 3 it has a positive polarity), which turns off the thyristor 25 (i25 0). In this case, the core current due to

5, the winding self-induction EMF continues to flow in the same direction through the shunt diode 29 between the sliding contacts 22, 23 (i29).

At time 1c, when the sliding contact 24 in the de-energized state, being on the insulating plate 17, starts to contact the plate 9, a control pulse is generated in the channel B2 of the position sensor, which, through the blocks 33, 34, 36, is generated by the Do signal turns on thyristor 25. This starts the switching process in the section connected to the plates 8, 9 and the core current flows along the circuit: plus source-25-29-22-8-section -9-24-minus power source . Over time t, the current of the shunt diode 29 decreases to zero i29 0), the current of the valve 25 reaches the value of the current core 025), in the section connected to the plates 8, 9, the current reversal process ends, and the core current flows so : plus source-25-23-4-winding-9-24-minus source.

At time t.4, when the sliding contact 23 moves to half of the insulating plate 13, or after the delay time tn y T has elapsed, the signal from the switch 25 025 0) appears at the output of the pulse amplifier 37. Or this, the core current due to the EMF of the self-induction of the winding continues to flow in the same direction through the diode 28 between the contacts 21, 24 and the plates 4, 9 028).

At the time ts, when the sliding contact 23, being on the insulating plate 13, comes into contact with the conductive plate 5, the valve 25 is turned on and the switching process starts, similar to the time ti. Next, the processes are repeated.

To adjust the speed of the machine using the delay unit 35, by adjusting the delay time, it is possible to vary

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pulse cycle duty cycle:

Ui / T, (1) and, consequently, the average stress on the cortex of the engine, i.e.

and 0 for Un. (2) A specific difference of the proposed device from the prototype is that it is applicable only in non-reversible electric drives.

Claims (1)

SUMMARY OF THE INVENTION A non-reversible direct-current DC electrical machine with a free-flow valve-mechanical switch, comprising a mechanical collector with conductive and insulating plates, two different-polarity brush groups in contact with it, consisting of two contacts, a control circuit, diodes, which are connected to the main circuit, connected between the incoming and outgoing contacts of different-polarity groups of brushes, a fully controllable semiconductor element connecting the mains terminal to the incoming contact of one h brush groups, characterized in that, for the sake of simplicity, it contains thyristors connected between the runaway contacts of the bipolar groups of brushes and the corresponding terminals of the mains, an incident contact of the brush group of a polarity opposite to the polarity of the group connected to the fully controllable element is connected to the corresponding terminal of the power supply, and in each unipolar group of brushes the incoming contact is displaced along the working surface of the collector relative to the running one by a distance equal to half the collector division. r U B & & J P / g