Valve motor: principle of operation and circuit

In order to solve tasks to control modern precision systems, the valve motor is increasingly used. This is characterized by a great advantage of such devices, as well as by the active formation of the computing capabilities of microelectronics. As you know, they can provide a high density of long-term torque and energy efficiency compared to other types of engines.

Diagram of a valve motor

The engine consists of the following parts:

1. The back of the case.
2. Stator.
3. Bearing.
4. Magnetic disk (rotor).
5. Bearing.
6. Stator with winding.
7. Front of the body.

The valve motor has a relationship between the multiphase winding of the stator and the rotor. They have permanent magnets and an integrated position sensor. Switching of the device is realized with the help of a valve converter, as a result of which it received such a name.

The layout of the valve motor consists of a back cover and a sensor printed circuit board , a bearing bush, a shaft and the bearing itself, rotor magnets, an insulating ring, a winding, a spring bolt, an intermediate sleeve, a Hall sensor, insulation, housing and wires.

In the case of connecting the windings with a "star" the device has large constant moments, so this assembly is used to control the axes. In the case of fastening the windings with a "triangle" they can be used to work at high speeds. Most often, the number of pairs of poles is calculated by the number of rotor magnets that help determine the ratio of electrical and mechanical revolutions.

The stator can be manufactured with a non-iron or iron core. Using such designs with the first option, it is possible to ensure that the rotor magnets are not attracted, but at the same instant, the engine efficiency is reduced by 20% due to the decrease in the value of the constant torque.

It can be seen from the circuit that in the stator the current is formed in the windings, and in the rotor it is created by means of high-energy permanent magnets.
Legend:
- VT1-VT7 - transistor communicators;
- A, B, C - phases of windings;
- M - motor torque;
- DR - rotor position sensor;
- U - motor supply voltage regulator;
- S (south), N (north) - the direction of the magnet;
- UZ - frequency converter;
- BR - speed sensor;
- VD - zener diode;
- L - coil of inductance.

The motor circuit shows that one of the main advantages of a rotor in which permanent magnets are installed is a reduction in its diameter and, as a consequence, a reduction in the moment of inertia. Such devices can be built into the device itself or located on its surface. The reduction of this indicator very often leads to small values of the balance of the moment of inertia of the engine itself and the load applied to its shaft, which complicates the operation of the drive. For this reason, manufacturers can offer a standard and an increased 2-4 times the moment of inertia.

Work principles

To date, it becomes very popular valve motor, the principle of operation of which is based on the fact that the device controller starts switching the stator windings. Due to this, the vector of the magnetic field remains always shifted by an angle approaching 900 (-900) relative to the rotor. The controller is designed to control the current that moves through the windings of the motor, including the magnitude of the magnetic field of the stator. Therefore, it is possible to adjust the torque that acts on the device. The angle indicator between the vectors can determine the direction of rotation that acts on it.

It should be taken into account that we are talking about electrical degrees (they are much smaller than geometric ones). For an example, let's give a calculation of a valve motor with a rotor, which in itself has 3 pairs of poles. Then its optimal angle is 900/3 = 300. These pairs provide 6 phases of the commutation windings, then it turns out that the stator vector can move by jumps to 600. From this it is clear that the real angle between the vectors will necessarily vary from 600 to 1200, starting with the rotation of the rotor.

A valve motor, the principle of operation of which is based on the revolution of the switching phases, because of which the excitation flux is maintained by a relatively constant movement of the armature, after their interaction, a rotating torque begins to form. He aspires to rotate the rotor in such a way that all the streams of excitation and anchors coincide. But during its turn, the sensor starts to switch windings, and the flow moves to the next step. At this point, the resultant vector will move, but remain completely immobile relative to the rotor flux, which ultimately creates the torque of the shaft.

Benefits

Using the valve motor in operation, it is possible to note its advantages:

- the possibility of applying a wide range for modifying the rotational speed;

- high dynamics and speed;

- maximum positioning accuracy;

- low maintenance costs;

- The device can be attributed to explosion-proof objects;

- has the ability to carry large overloads at the moment of rotation;

- high efficiency, which is more than 90%;

- there are sliding electronic contacts, which significantly increase the working life and service life;

- With prolonged operation there is no overheating of the motor.

disadvantages

Despite the huge number of advantages, the valve motor also has disadvantages in operation:
- quite complicated control of the electric motor;
- a relatively high price of the device due to the use in its design of the rotor, which has expensive permanent magnets.

Valve inductor motor

The valve-inductor motor is a device in which switching magnetic resistance is provided. In it, the conversion of energy occurs due to a change in the inductance of the windings, which are located on the pronounced stator teeth when the gear magnetic rotor moves. The power supply device receives from the electrical converter, alternately switching the windings of the motor in rigor to move the rotor.

The valve-inductor motor is a complex complex system in which components that are diverse in their physical nature work together. For the successful design of such devices, in-depth knowledge in the field of designing machines and mechanics, as well as electronics, electromechanics and microprocessor technology is required.

The modern device acts as an electric motor, acting in conjunction with an electronic converter, which is manufactured using integrated technology using a microprocessor. It allows to implement high-quality engine management with the best energy conversion rates.

Motor properties

Such devices have high dynamics, high overload capacity and precise positioning. Due to the fact that they do not have moving parts, their use is possible in an explosive and aggressive environment. Such motors are also called brushless, their main advantage, in comparison with the collector ones, is the speed, which depends on the supply voltage of the load torque. Also one more important property is the absence of abradable and rubbing elements that switch contacts, due to which the resource of using the device grows.

DC Duct Motors

All DC motors can be called brushless. They operate from a network with a direct current. The brush assembly is provided for electrically combining the rotor and stator circuits. This detail is the most vulnerable and difficult enough to maintain and repair.

The DC ventilator operates on the same principle as all synchronous devices of this type. It is a closed system, including a power semiconductor converter, a rotor position sensor and a coordinator.

Alternating current gate valves

Such devices receive their power from AC networks . The speed of rotation of the rotor and the motion of the first harmonic of the magnetic force of the stator completely coincide. This engine subtype can be used at high power. This group includes step and reactive valve devices. A distinctive feature of stepper devices is the discrete angular displacement of the rotor during its operation. The supply of windings is formed by means of semiconductor components. The control of the fan motor is carried out with a successive displacement of the rotor, which creates a switching of its power from one winding to the other. This device can be divided into single-, three- and multi-phase, the first of which can contain a starting winding or a phase-shifting circuit, and can also be started manually.

Principle of synchronous motor operation

The gate synchronous motor operates on the basis of the interaction of the magnetic fields of the rotor and the stator. Schematically, the magnetic field during rotation can be represented by the pluses of these same magnets, which move with the velocity of the stator magnetic field. The rotor field can also be depicted as a permanent magnet that makes rotations synchronously with the stator field. In the absence of an external torque, which is applied to the shaft of the apparatus, the axes completely coincide. The acting forces of attraction pass along the entire axis of the poles and can compensate each other. The angle between them is equated to zero.

In the event that the braking torque is applied to the machine shaft, the rotor moves to the side with a delay. Due to this, the forces of attraction are divided into components that are directed along the axis of plus indicators and perpendicular to the axis of the poles. If an external torque is applied that creates acceleration, that is, it starts acting in the direction of rotation of the shaft, the picture of the interaction of the fields will completely reverse. The direction of the angular displacement begins to transform to the opposite, and in this connection the direction of the tangential forces and the effect of the electromagnetic moment change. In this situation, the engine becomes braking, and the device works as a generator that converts the mechanical energy supplied to the shaft into electrical energy. Then it is redirected to the network feeding the stator.

When there is no external, apparent pole moment, it will begin to assume a position at which the pole axis of the stator magnetic field will coincide with the longitudinal axis. This placement will correspond to the minimum flow resistance in the stator.

If the brake torque is applied to the shaft of the machine, the rotor will deflect, while the stator magnetic field will be deformed, since the flow tends to close at the lowest resistance. To determine it, we need force lines, the direction of which in each of the points will correspond to the motion of the action of the force, so a change in the field will lead to the appearance of a tangential interaction.

Having considered all these processes in synchronous engines, it is possible to reveal the demonstrative principle of reversibility of various machines, that is the possibility of any electrical apparatus to change the direction of the converted energy to the opposite.

Brushless motor with permanent magnets

A permanent magnet valve motor is used to solve serious defense and industrial tasks, since such a device has a large supply of power and efficiency.

These devices are most often used in industries where relatively low power consumption and small dimensions are needed. They can have a wide variety of dimensions, without technological limitations. At the same time, large devices are not completely new, they are most often produced by companies that are trying to overcome the economic difficulties that limit the range of these devices. They have their advantages, among which one can note the high efficiency due to losses in the rotor and a greater power density. To control brushless motors, a frequency-controlled drive is required.

An analysis of costs and results shows that devices with permanent magnets are much preferable, as compared to other, alternative technologies. Most often they are used for industries with a fairly heavy work schedule of marine engines, in the military and defense industries and other units, the number of which is continuously increasing.

Jet engine

The valve-jet engine operates using two-phase windings, which are mounted around diametrically opposite poles of the stator. The power supply moves to the rotor in accordance with the poles. Thus, his opposition is completely reduced to a minimum.

The valve motor, created by its own hands, provides a high-speed drive with optimized magnetism for working with the reverse. The information about the location of the rotor is used to control the phases of the voltage supply, since this is optimal for achieving a continuous and smooth torque and high efficiency.

The signals that the jet engine emits are superimposed on the angular unsaturated phase of the inductance. The minimum pole resistance fully corresponds to the maximum inductance of the device.

A positive moment can be obtained only at angles, when the indicators are positive. At low speeds, the phase current must necessarily be limited in order to protect the electronics from high volt-seconds.
The mechanism of transformation can be illustrated by a line of reactive energy. The power sphere is characterized by a food that is transformed into mechanical energy. In the case of its sudden disconnection, excess or residual force returns to the stator. Minimum indicators of the influence of the magnetic field on the performance of the device are its main difference from similar devices.