RU2075821C1 - Contactless dc motor - Google Patents

Abstract

FIELD: DC drives, in the first place, in low-speed and torque devices (for instance, in power dumping of flat-cars used as a torque motor). SUBSTANCE: motor has a two-phase winding, whose sections are connected in a bridge circuit, four rotor position pickups shifted in space relative to each other through 90 electrical degrees, and an electronic switching circuit built around four transistors. The outputs of the diametrically arranged rotor position pickups are connected to the bases of the like transistors. EFFECT: improved design. 2 dwg

Description

The present invention relates to the field of electrical engineering, in particular, to non-contact DC motors and can be used in DC drives, primarily in low-speed drives, as well as in torque devices (for example, in the power unloading of gyroplatforms as a torque sensor motor torque), where a minimum unevenness of torque is required when the rotor is rotated 360 ^o .

Known non-contact DC motor containing a two-phase winding, the sections of which are connected to each other by a bridge circuit, rotor position sensors of the motor and a two-bridge electronic switching circuit, each bridge which is made of four power transistors forming complementary pairs controlled by position sensors of the rotor of the motor through intermediate transistors moreover, the diagonals of the bridge circuit of the two-phase motor winding [I] are connected to the diagonals of these bridges
A disadvantage of the known non-contact DC motor is the complexity of the electronic switching circuit and the low reliability in operation due to the presence of a large number of electronic components, and also because the failure of at least one of the transistors of the switching circuit leads to a failure of the motor as a whole. In addition, this engine has a significant torque unevenness, the value of which can reach ± 15%
Another non-contact DC motor is known, which is an improved modification of the above, where power transistors of the electronic switching circuit are controlled directly from the position sensors of the rotor of the motor [2]
This motor is the closest in technical essence to the claimed one and contains a two-phase winding, the sections of which are connected by a bridge circuit, and the tops of the bridge winding circuit are connected to the power buses via the keys of a two-bridge electronic switching circuit made on eight power transistors, controlled by four rotor position sensors engine.

 However, this scheme is quite complex and does not provide sufficient reliability in operation and, in addition, like the analogue described above, has a significant non-uniformity of torque.

 The aim of the present invention is to eliminate these drawbacks, i.e., simplifying the circuit, increasing reliability and reducing the unevenness of torque.

 The solution to the constant problem is achieved by the fact that in a non-contact DC motor containing a two-phase winding, the sections of which are connected by a bridge circuit, and the vertices of the bridge winding circuit are connected to the power buses through the keys of an electronic switching circuit controlled from four position sensors of the rotor of the motor, an electronic switching circuit made in the form of two power pnp transistors and two power npn transistors connected by emitters to the corresponding power bus, collectors of the same transistors sub One to the appropriate diagonal bridge circuit the motor winding, the sections of which forming opposite arms of the bridge are connected to adjacent sections homonymous pin and base of like transistors are connected to the outputs diametrically opposite the motor rotor position sensors.

 The invention is illustrated by drawings, where in Fig. I shows a schematic electrical diagram of the inventive engine, in Fig.2 the location of the position sensors of the rotor of the engine, and Fig.3 diagram of the engine.

 The contactless DC motor (Fig. I) contains four chains of series-connected sensors I (2, 3, 4) of the position of the motor rotor and resistor 5 (6, 7, 8), connected between the power buses, and an electronic switching circuit made on two power pnp transistors 9, 10 and two power npn transistors 11, 12, the emitters of which are connected respectively to the positive and negative power buses. The rotor position sensors are displaced in space relative to each other in increments of 90 degrees. moreover, the sensors I and 3 are located diametrically to the sensors 2 and 4, respectively. The findings of the sensors I and 2 are connected respectively to the pnp bases of transistors 9 and 10, and the outputs of the sensors 3 and 4 to the npn bases of transistors 11 and 12. The two-phase motor winding is made in the form of identical sections 13, 14, 15 and 16, interconnected along the bridge the scheme, and the sections forming the opposite shoulders of the bridge are connected to adjacent sections with the same conclusions. The collectors of transistors 9 and 10 are included in one diagonal of the bridge circuit of the winding, and the collectors of transistors 11 and 12 in the other.

 In this case, it is preferable to use photosensors as sensors for the position of the motor rotor: a pair of photodiode-LEDs, as well as magnetoelectric high-frequency sensors.

 When the motor rotor turns, the power transistors of the switching circuit are sequentially opened. In section A (Fig. 3), the sensors I and 4 open transistors 9 and 12, and the current flows from point "a" to point "g" directly (full current) and through points "b", "c" and "g" one third of the total current. The resulting magnetic flux is shown by arrow M. After the rotor rotates by 45 el. hail. (section B) transistor 11 is additionally opened, and as a result, currents flow through windings 13 and 16, there is no current in windings 15 and 14. The vector M of the field rotates 45 degrees. counterclock-wise. After another 45 elgrad. in section B, the transistor 12 is locked, the transistors 9, 11 remain open, the currents flow through the winding 13 (full current) and through the windings 16,15,14 (one third of the total current). And after 45 elgrad. (section D) additionally opens the transistor 10. Next is a similar process.

 Thus, when the rotor rotates 360 degrees. the field vector occupies eight fixed positions, every 45 elgrad. which provides the specified small non-uniformity of the moment.

 The inventive non-contact DC motor is much simpler in its circuit solution compared to the analogue and prototype described above and has increased reliability both due to the fact that the motor windings are connected between complementary pairs of transistors (this eliminates the possibility of a short circuit of the power supply), and due to reduce the number of electronic components.

Information sources:
1. Japan Accepted Application N 49-11481, cl. 56 A 42
2. US Patent N 4847540, H 02 K 29/12, 1989

Claims (1)

 A non-contact DC motor containing a two-phase winding, the sections of which are connected by a bridge circuit, and the tops of the bridge winding circuit are connected to the power buses through the keys of the electronic switching circuit, controlled from four position sensors of the rotor of the motor, characterized in that the electronic switching circuit is made in the form of two power pnp transistors and two power npn transistors connected by emitters to the corresponding power bus, collectors of the same transistors are connected to the corresponding the diagonal of the bridge circuit of the motor winding, the sections of which, forming the opposite shoulders of the bridge, are connected to adjacent sections by the terminals of the same name, and the bases of the same name transistors are connected to the outputs of the diametrically located rotor position sensors of the motor.

Images