RU2510565C1 - Low-speed current generator - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: low-speed current generator has, mounted on a shaft, a rotor with a multipolar system of permanent magnets, a stator in form of a magnetic conductor and stator windings, leads of which are connected to corresponding rectifier units, a high-frequency pulse master generator and as many power correctors as there are rectifier units, each connected to the output of the corresponding rectifier unit and control inputs of which are connected to the output of the high-frequency pulse master generator, wherein the stator is single-sectional, and the number of poles of the rotor differs by one from the number of stator windings, the stator being cogless.

EFFECT: high stability of operation of the generator.

3 cl, 4 dwg

Description

The invention relates to the field of electrical engineering and can be used to create magnetoelectric current generators for wind power plants and micro hydroelectric power stations, which use the energy of low-speed carriers, for example, wind, river flows and stable underwater currents.

A known current generator comprising a housing with bearings holding the shaft, disk magnetic circuits and axially magnetized main permanent magnets with alternating polarity, stator winding coils, rotor position sensors, control unit, additional rows of permanent magnets placed between the main magnets, and the permanent magnets are installed in clips, interconnected with the formation of the housing and toroidal gaps, in the space of which are placed electrical units, moreover, alternating magnetic The fraction of magnets is directed towards each other, and the conclusions of the rotor position sensors are connected to the contacts of the dielectric ring and through the holes of this ring and the hollow shaft are connected to the control inputs of the control unit, and the phase sections of the coils are also connected to the contacts of the dielectric ring, and in series of electrical blocks are connected in series either in parallel or in series-in parallel and through the holes of the dielectric rings and the hollow shaft are connected to the load, and by other terminals to the power switches of the unit ia [RU 2147155 C1, H02K 29/06, 04/04/1998].

The disadvantages of this device include the presence of rotating coils and sliding current collectors, which leads to a deterioration in the energy characteristics of the generator and a decrease in reliability.

Also known is a magnetic electric current generator comprising a housing, a stator including a magnetic system, magnetic cores, coils, and a rotor, while the magnetic systems of the stator and rotor are made in the form of magnetic blocks, each of which consists of a series of magnets placed at intervals, size which are not less than the size of the magnet in the direction of motion of the rotor, and the magnetization of each magnet is oriented at an angle selected in the range from +90 to -90 ° relative to the direction of motion of the rotor, with alternating successive poles of the magnet arrangement of the magnet and the coil are placed on the magnetic cores, the stator magnet pole NO [RU 2147153 C1, H02R 21/04, 21/14 H02K, H02K 21/24, 08.07.1998].

This technical solution has two magnetic systems with permanent magnets (on the rotor and on the stator), and in the interval between them there are ferromagnetic magnetic cores, moreover, each coil is wound on its core, which leads to an uneven distribution of magnetic flux, i.e. to reduce power, efficiency and manufacturability.

In addition, a low-speed electric machine is known, comprising a ring-shaped row of stator windings on iron cores made of sheets or pressed iron powder, and a corresponding ring-shaped row of permanent rotor magnets, in particular, a synchronous machine with a constant magnetization of rotor magnets to generate sinusoidal voltage, and the windings are made concentrated , the cores with windings alternate with the iron cores without windings so that on every second iron core there is a winding, the number of gaps between the cores differs from the number of poles, while the number of gaps between the cores s and the number of poles p follows the expressions | sp | = 2 · m and s = 12 · n · m, where n and m are natural numbers, and the machine is designed to generate a three-phase voltage with a series connection of adjacent coils to obtain ^• m such groups per phase that can be connected in series or in parallel [RU 2234788, C2, H02K 21/24, H02K 21/12, 05.25.2000].

The disadvantage of this electric machine is that the gaps between the individual stator cores reduce the efficiency, power and manufacturability of its manufacture.

In addition to the above, a device is known that contains an annular row of stator windings and a corresponding annular row of permanent rotor magnets, moreover, the stator is made in the form of a toroidal magnetic circuit, and the rotor consists of two parts, the first of which is a shaft with welded disks, and the second - disks with magnets when the width of the disks is equal to the length of the magnets attached to the disks of the first part, while the gap between the stator and the rotor magnets is in the range of 0.1 ÷ 2.0 mm [RU 71189, U1, H02K 21/24, H02K 23/04 02/27/2008].

The disadvantage of this technical solution is the relatively large moment of stragging, which reduces the stability of its operation under unstable external exposure to low-speed energy carriers. In addition, this technical solution has a relatively high material consumption, since, in particular, the stator is made in the form of a toroidal magnetic circuit.

The closest in technical essence and functionality to the claimed one is a low-speed current generator containing a shaft, a stator made in the form of a magnetic circuit and stator windings, the terminals of which are connected to a rectifier unit, as well as a rotor mechanically connected to the device shaft and having a set of permanent magnets Moreover, the magnetic circuit is made in the form of prismatic rods radially oriented from the shaft axis, drawn from strips of electrical steel, and the permanent magnets of the rotor are fixed by consistently around the ends of the prismatic rods at intervals and with an alternating sequence of poles from magnet to magnet, moreover, the stator windings are wound on the ends of the prismatic rods remote from the shaft axis, the number of prismatic rods is one less than the number of permanent magnets, and prismatic rods, in a particular case , made the elongation factor of 3-20 [RU 98646, U1, H02K 23/04, 10.20.2010].

The disadvantage of the closest technical solution is the relatively low stability under conditions of fluctuations in the magnitude of the external impact, including possible attenuation.

The required technical result is to create a device in which, due to the introduced technical improvements, the stability of the generator is increased.

The required technical result is achieved by the fact that, in a device containing a rotor mounted on a shaft with a multi-pole system of permanent magnets, as well as a stator made in the form of a magnetic circuit and stator windings, the terminals of which are connected to their respective rectifier units, a master generator of high-frequency pulses and correctors are introduced power according to the number of rectifier blocks, each of which is connected to the output of the corresponding rectifier block and whose control inputs are connected to the output of the master oscillator ora high frequency pulses, wherein, the stator is a one-and number of rotor poles is different for one of the number of stator windings configured toothless.

In addition, the required technical result is achieved in that, the number of poles of the rotor is 18, and the number of stator windings is one less.

In addition, the required technical result is achieved by the fact that the outputs of the power corrector through the corresponding inverters are connected to the combined input of the current consumer of the low-speed generator.

The drawing shows:

figure 1 is a functional diagram of a low-speed current generator;

figure 2 is a schematic diagram of a rectifying unit with a power corrector connected at its output, having a control input for supplying a control signal from a master generator of high-frequency pulses, and an output winding of a transformer, which is connected through a diode to a current consumer, for example, a battery;

figure 3 - gear (figure 3, a) and toothless (figure 3, b) of the stator structure.

The low-speed current generator (Fig. 1) contains a rotor mounted on the shaft 1 with a multi-pole system of permanent magnets 2, as well as a stator made in the form of a magnetic circuit 3 and stator windings 4, the terminals of which are connected to their respective rectifier blocks, at the outputs of each of which are included their corresponding power corrector, control inputs (“Control” input in figure 2) which are connected to the output of the master generator of high-frequency pulses (not shown in the drawing), moreover, the stator is made single-section, and the number the rotor poles differs by one from the number of stator windings made by toothless. In addition, the outputs of the power corrector included in the outputs of the rectifiers (Fig. 2) are connected to separate inverter blocks for each secondary winding of the output transformer T1 of the power corrector and their currents are added to the total current already in the load, for example, of storage batteries (batteries).

Low-speed current generator operates as follows.

When the shaft 1 is rotated, which is connected to the blades of a wind generator or micro hydroelectric power station, the rotor mounted on the shaft 1, made in the form of a multi-pole system of permanent magnets 2, also rotates, which leads to the appearance of alternating electric current in the stator windings 4, which is rectified in rectifier blocks, made with power correctors at the outputs, which are controlled by signals from a master generator of high-frequency pulses, and is supplied to the consumer.

Typically, such generators have a three-section three-phase stator, but within one pole angle the power moment still fluctuates and these oscillations prematurely destroy the wind wheel. In the proposed device, the rotor has, for example, 18 poles of permanent magnets, and the stator is made lead-free and contains one less coil.

In addition, the often used magnetic circuit design on the stator, as a rule, has an annular short circuit between the poles and a tooth is made at each pole of the magnetic system, piercing the stator winding and with a minimum clearance suitable for the rotor magnet. When the rotor rotates, large irregularities in the moment arise on these teeth, which remain even in the three-phase stator. In the proposed design of the generator, the magnetic circuit on the stator is toothless, which makes it possible to ensure a breakaway moment close to zero.

The problem of power take-off under varying external influences is solved by applying a 17-phase power corrector (one each connected at the outputs of the corresponding 17 rectifier units), i.e. through digital control of power corrector, and not by the traditional creation of, for example, aerodynamic brakes on a wind wheel or the use of hydrovariators that have a high cost.

Each of the stator windings 4, when the rated current flows through it, makes a contribution on the shaft 1 to the power moment in the form of two humps of maximum torque for each electric period, between which the moment becomes almost zero. Therefore, for other designs with the same number of poles on the stator and on the rotor, when all the coils of one (out of three) sections are connected into a single current circuit, the power moment of each section is highly modulated. This phenomenon is especially dangerous for low-speed generators, because attempts to “smooth out” the torque response in three phases leave strong moment pulsations at frequencies comparable to resonant mechanical frequencies, for example, a wind wheel.

In the proposed design, each of the independent stator windings 4 also gives two humps of torque on the shaft 1. But the smoothing of the torque characteristic within one pole step is carried out in 17 phases, as a result of which the final torque characteristic of the low-speed current generator as a whole is almost constant in angle.

In addition, the manufacture of a three-section stator leads to an increase in the cost of the generator as a whole compared to the use of the proposed single-section stator.

The outputs of the power corrector included in the outputs of the rectifiers VD1 ... VD4 (Fig.2) are connected to separate blocks of inverters for each secondary winding of the output transformer T1 of the power corrector and their currents are added to the total current already in the load, for example, of storage batteries (batteries). This allows you to reduce the power of each unit and use less powerful electronic parts.

The bridge rectifier is made in the usual way on four diodes VD1 ... VD4. The capacitor C1 is not smoothing - it must store a charge sufficient for only one cycle of the inverter and serves only to protect the rectifier diodes. The voltage shape on the capacitor C1 is shown in the diagram (figure 2). If you need better rectifier protection, instead of C1 capacitor, you can use a U-shaped low-pass filter with a cutoff frequency higher than the maximum frequency of the sinusoidal voltage in the generator windings, but much lower than the inverter switching frequency.

A significant problem is that the rectified voltage varies in the range of 20 ... 200 V, i.e. can be either higher or lower than the battery voltage. Therefore, it is advisable to use a corrector with a transformer. The power corrector contains a key transistor VT1 and a transformer T1. The transistor opens with short pulses with a repetition rate of 30 ... 100 kHz, coming to the “Control” input from the master generator of high-frequency pulses. During the pulse, energy is accumulated in the primary winding of transformer T1, moreover, the current in the winding increases linearly, but does not reach the saturation current of the transformer ferrite magnetic core even at the maximum voltage at the rectifier output. Under these conditions, the uniform load of the output of the low-speed current generator is ensured for a fixed duration and repetition rate of the opening pulses, so all 17 power correctors can be fed through the base (gate) circuits of the key transistors from one common control source.

After the end of the control pulse, the transistor VT1 closes, and a positive pulse is generated on its collector (drain), which must be dumped into the load. The voltage of the discharge of energy into the load is selected obviously higher than the maximum rectified voltage. If this were the battery voltage, then the diode for dumping energy into the load could be connected directly to the collector (drain) of the key transistor. But, since it is significant, for example, 5 times smaller, therefore, you can use the secondary winding with a transformation ratio, for example, 5: 1.

When the voltage pulse on the primary winding reaches, for example, 240 V, and on the secondary - 48 V, the energy stored in the transformer’s magnetic core is discharged through the VD5 diode to the battery at its rated voltage of 48 V. Since the energy is reset automatically, its output self-regulates voltage, all 17 power corrector outputs can be connected in parallel, and, nevertheless, all of them will give a current to the battery, more or less, depending on the current phase of the alternating voltage on each winding 4 of the stator.

Another quality problem of low-speed current generators is the breaking moment, which should be as low as possible so that, for example, the wind wheel does not slow down in light winds. The moment of breaking is caused by residual potential holes on the shaft at zero generator current.

In the known designs of such low-speed current generators, the tooth structure of the stator magnetic circuit is used. The proposed technical solution uses a toothless design. We give evidence of the effectiveness of using such a construction.

To do this, we carry out a theoretical justification for the operation of the magnetic circuit.

In electrodynamics, the formula is known:

$$B={\mu }_0*\mu *H\left(\mathrm{one}\right)$$

where µ0 = 4 * π * 10 ^-7 is the magnetic permeability of the vacuum (constant);

µ ~ 7000-14000 dimensionless material science characteristic - magnetic permeability of electrical steel.

In accordance with formula (1), the magnetic induction B at the end of the tooth of Fig. 3a sets the magnitude of the magnetic force of interaction with the permanent magnet - i.e. the magnitude of the power moment on the shaft. The magnetic field strength H is uniquely related to the number of ampere turns N * I of the stator windings and is determined by the formula:

$${\displaystyle \oint \overrightarrow{H}*d\overrightarrow{l}=N*I\left(2\right)}$$

Thus, it can be argued that the stator magnetic circuit works the more efficiently, the greater the magnetic permeability of the circuit µ.

It should be noted that formula (1) was obtained under the assumption that the one-dimensional magnetic field is uniform.

составляет не 7000-14000, а лишь:In real short magnetic circuits with gaps and with curved lines of force that are characteristic of the analogues considered above, the action of open Faraday demagnetizing poles is the determining factor, as a result of which the real ratio $$\mu =\frac{B}{{\mu }_0*H}$$

is not 7000-14000, but only:

$$\frac{B}{{\mu }_0*H}={\mu }_{\mathrm{uh}ff}=3.6-3.8\left(3\right)$$

where µ _eff is the integral characteristic of non-uniform fields - the effective magnetic permeability of the magnetic circuit.

и заменяется на участок с сильным полем $$\overrightarrow{H}$$

, что повышает, тем самым, потребный вес меди N*I. Однако следует учесть, что в магнитной цепи всегда должен оставаться участок сильных полей $$\overrightarrow{H}$$

,Thus, the analogues of the proposed low-speed current generator with a tooth structure of the stator magnetic circuit have an efficiency of magnetic circuits in terms of saving the weight of copper, and so is not high. In the proposed technical solution, when the teeth are removed, we really somewhat deteriorate the power qualities of the magnetic system. In particular, integral (2) excludes a whole section of the magnetic circuit with weak fields $$\overrightarrow{H}$$

and replaced with a strong field $$\overrightarrow{H}$$

, which increases, thereby, the required weight of copper N * I. However, it should be noted that in the magnetic circuit there must always remain a section of strong fields $$\overrightarrow{H}$$

,

corresponding to the thickness of the permanent magnets, so in relative terms, the deterioration (3) is not so big:

$$\frac{B}{{\mu }_0*H}={\mu }_{\mathrm{uh}ff}=2.6-\mathrm{2,8}\left(\mathrm{four}\right)$$

Therefore, the toothless implementation and stator windings does not create potential holes and provides a moment of breaking close to zero.

Thus, thanks to the introduced improvements, the required technical result is achieved, which consists in increasing the stability of the generator without affecting its technical and economic indicators.

Claims (3)

1. A low-speed current generator comprising a rotor mounted on a shaft with a multi-pole system of permanent magnets, as well as a stator made in the form of a magnetic circuit and stator windings, the terminals of which are connected to their respective rectifier units, characterized in that a master generator of high-frequency pulses and power correctors are introduced by the number of rectifier blocks, each of which is connected to the output of the corresponding rectifier block and the control inputs of which are connected to the output of the master oscillator frequency pulses, the stator being made single-section, and the number of rotor poles differs by one from the number of stator windings made by toothless. 2. The low-speed current generator according to claim 1, characterized in that the number of rotor poles is 18, and the number of stator windings is one less. 3. The low-speed current generator according to claim 1, characterized in that the outputs of the power corrector through the corresponding inverters are connected to the combined input of the current consumer of the low-speed generator.

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