RU2274556C2 - Regenerative brake with revolving magnetic field - Google Patents

Abstract

FIELD: transport engineering.

SUBSTANCE: proposed regenerative brake with revolving magnetic field can be used in automotive vehicles. Said brake accumulates kinematic energy at braking and uses it at accelerating the vehicle. To reduce number of parts and energy transmissions, brake is fitted in wheel and is made in form of combination squirrel-cage electric machine consisting of three main parts: fixed one-axle with fitted-on field windings; movable one, rigidly secured on wheel, with communicating windings, frequency multipliers and flywheel windings; and freely rotating one - i.e. flywheel (squirrel-cage rotor of induction machine). In process of braking, revolving magnetic field opposite to direction of wheel rotation is created on field windings. Said field, through communicating windings and flywheel windings, acts onto flywheel causing its spinning. At acceleration direction of exciting field is changed. Said field, through elements of movable part, causes braking of flywheel with transmission of energy to movable part, i.e. to vehicle wheel.

EFFECT: increased efficiency of vehicle by using energy of flywheel at acceleration.

4 dwg

Description

Technical field

The proposed regenerative brake with a rotating magnetic field (hereinafter the proposed brake) relates mainly to the automotive industry and can be used to create a braking system that converts the kinetic energy of the car into the kinetic energy of the flywheel during braking and then accelerates when converting the energy of the flywheel to the kinetic energy of the car. It can also be used on other modes of transport that have sources of electricity.

State of the art

Existing automobile brake systems convert kinetic energy into heat energy with its subsequent dissipation in the atmosphere, which leads to significant fuel losses (when the bus moves around the city cycle up to 50%) and parts wear out.

Recuperative braking systems are known, for example, the Girekt planetary regenerative brake / N.V. Gulia, Energy Storage, Moscow, Nauka, 1980, p. 138 /, which was adopted as a prototype. In it, the flywheel with the transmission is connected by a mechanical four-speed transmission. It was not widely used for reasons: design complexity; step change in gear ratio between the flywheel and the transmission, which does not ensure smooth operation; a significant part of the flywheel’s energy could not be used, because the number of revolutions of the flywheel should be greater than the number of revolutions of the transmission by the number of times equal to the gear ratio.

SUMMARY OF THE INVENTION

The proposed brake is a combined brushless asynchronous electric machine with a squirrel-cage rotor without rigid mechanical connections between the main parts, the energy transfer in which is carried out by electromagnetic flows. Its use does not exclude the presence of a conventional brake system on a car for the purpose of traffic safety.

To accumulate and store energy, as in the prototype, a flywheel was used for reasons: simplicity of design, the ability to instantly receive and give a large amount of energy, the ability to be made in the form of a short-circuited rotor of an asynchronous electric machine.

For transformations and energy transfers, a combined asynchronous electric machine with a squirrel-cage rotor was used for the reasons: simplicity of design / lack of collector /, reversibility, reversibility.

In order to reduce the number of rotating parts, the proposed brake is mounted on one axis, which makes it possible to place it directly in the car wheel. In addition to simplicity, this design allows you to distribute the converted energy by the number of wheels, which will reduce its density on the flywheel.

Enumeration of figures.

Figure 1. General scheme of a regenerative brake with a rotating magnetic field. It consists of three main honors: fixed / axis 6 with excitation windings 4 located on it, three-phase, connected by a star, with terminals A, B and C /; movable, fixed rigidly on the car wheel / intermediate windings 3, electronic frequency multipliers 1, flywheel windings 2 / and freely rotating / flywheel 5, made in the form of a short-circuited rotor of an asynchronous electric machine /.

Figure 2. Diagram of directions of rotation during braking: 7 - magnetic field of windings 4, 10-magnetic field of windings 2 / Fig. 1/, 8 - car wheels, 9 - flywheel 5.

Figure 3. Diagram of directions of rotation during acceleration: 7 - the magnetic field of the windings 4, 10 - the magnetic field of the windings 2 / Fig. 1/, 8 - the wheels of the car, 9 - the flywheel 5.

Figure 4. General view of the flywheel 5. 11 - core, 12 - winding.

The work of a regenerative brake with a rotating magnetic field according to the general scheme, figure 1. Excitation windings 4 are fixed on the stationary / relative to the car / axle 6. When the wheel rotates, intermediate windings 3, frequency multipliers 1 and flywheel windings 2 rotate relative to them. Pair: windings 3 and windings 4 are necessary to create torque / negative when braking, counterclockwise arrows, and positive during acceleration, clockwise in FIGS. 2 and 3 / and brushless transmission of electricity from the fixed part of the brake to the moving one. When a three-phase electric current is supplied to the field windings 4, a rotating magnetic field of direction 7 appears in them (Fig. 2, braking). It excites in the intermediate windings 3 a three-phase electric current of the same sequence of phases with a frequency n = n ₁ + n ₂ , where n ₁ is the frequency of rotation of the field of field windings 4, n ₂ is the frequency of rotation of the wheel in direction 8/2 /. Frequency electronic multipliers 1 act as a step-up reducer when transmitting electric current from the intermediate windings 3 to the flywheel windings 2. Pair: intermediate windings 3, flywheel windings 2 are presented as an unified three-phase system for illustrative purposes. The direction of rotation of the field 10 in the windings of the flywheel 2 is opposite to the direction of rotation of the field 7 in the windings 3 and 4 due to a change in the sequence of phases B and C. This is necessary so that the direction of rotation of the field 7 during braking is opposite to the direction of rotation of the wheel 8 / Fig. 2 /.

Figure 2. Braking. A three-phase electric current is supplied to the windings 4. A rotating magnetic field of direction 7 arises in them, which is inhibitory for the moving part of the brake mounted on the wheel. In the intermediate windings 3, a three-phase electric current is excited, which is transmitted through frequency multipliers 1 to the flywheel windings 2, on which the rotating magnetic field has an opposite direction and a high speed. Pair: flywheel windings 2, flywheel 5 operates as an squirrel-cage induction motor, where windings 2 are a stator, flywheel 5 is a rotor. The flywheel begins to rotate in direction 9. Thus, the negative torque of the windings 4 is converted to a positive flywheel 5.

Figure 3. Acceleration The flywheel rotates in direction 9. A three-phase electric current is supplied to the windings 4 to create a rotating magnetic field of direction 7. In this case, a rotating magnetic field of direction 10 opposite to the direction of rotation of the flywheel 9 appears in the windings of the flywheel 2. Eddy currents appear in the short-circuited winding of the flywheel, creating moment relative to windings 2, which acts through the windings 2 on the wheel and rotates it in direction 8. Couple: windings of flywheel 2, flywheel 5 works as an induction motor Opposition mode.

Figure 4. Flywheel, made in the form of a squirrel-cage rotor of an asynchronous electric machine. Since in the proposed brake it constantly works in transient modes, i.e. in inrush current modes, it should be performed taking into account this, in the form of a double squirrel cage, for example.

When braking on the frequency of rotation of the wheel n _{2 the} proposed brake works as an asynchronous generator with a power consumption of excitation up to 5% of the nominal. According to the frequency of rotation of the magnetic field of the field windings, n ₁ operates as an induction motor in the opposition mode with a power consumption of 100% nominal. To reduce the frequency n ₁ while maintaining the maximum speed of the flywheel, electronic frequency multipliers 1 are used, which act as a step-up gearbox.

Assuming that bus weighing 10 tons moves at a speed of 36 km / h, having a kinetic energy E = mυ ^2/2 = 10000 · 100/2 = 500000 = 500 kJ, begins to slow down, then the allowable flywheel energy density formed in in the form of a disk with an opening of 10 kJ · kg / N.V. Gulia, Energy Storage, Moscow, Nauka, 1980, p. 148 / mass of one flywheel when placed on all wheels should be equal to m = 500 kJ / 10 kJ · kg / 4 = 12.5 kg, which is quite acceptable for practical use.

Benefits:

- a significant reduction in the amount of thermal energy released into the atmosphere during braking, increasing the efficiency of the car as a whole,

- lack of wearing parts,

- facilitating the operation of the car engine during acceleration,

- fuller use of flywheel energy in comparison with the prototype.

Disadvantages:

- the presence on the vehicle of a source of alternating multiphase electric current,

- there is an opposition mode, which leads to additional energy costs for the promotion of the flywheel,

- the relative complexity of adjusting the torques.

Claims (1)

A regenerative brake with a rotating magnetic field, comprising an asynchronous machine located in the vehicle’s wheel and a recuperated energy storage device, characterized in that it is made of three main parts: fixed, made in the form of a common axis of rotation with a multiphase field winding fixed to it, movable rigidly connected to the vehicle wheel and carrying intermediate windings and frequency multipliers, playing the role of an electronic rotating gear to lower the frequency of the alternating excitation creeping electric current, and freely rotating, consisting of a flywheel made in the form of a short-circuited rotor of an asynchronous electric machine, which is switched on by supplying a multiphase alternating electric current to the excitation windings, creating a rotating magnetic field of direction corresponding to the braking or acceleration modes.

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