JP7116697B2 - generator - Google Patents

Description

TECHNICAL FIELD The present invention relates to a power generator that generates power using the energy of wind or water.

There are conventional technologies related to power generators that control the excitation current based on the number of revolutions (see Patent Documents 1 and 2, for example). Patent Literature 1 detects the rotation of a propeller of a wind power generator, and if it is equal to or less than a predetermined rotation threshold, turns off the excitation to reduce the rotation load caused by the excitation so as not to stop the rotation. In Patent Document 2, in a charging device for a vehicle, the constant voltage power generation control at high rotation is performed by reducing the excitation current at high rotation.

As described above, in the conventional electromagnet generator, depending on the rotating body that supplies rotational force to the electromagnet generator, the power source of the rotating body does not have enough energy to rotate at a predetermined set number of revolutions or more. Sometimes. For example, when a small propeller for wind power generation is connected to an electromagnet generator, if the wind speed is strong, the rotation speed of the electromagnet generator can reach the set rotation speed at which power can be generated or higher.

However, when the wind speed is low, the rotation speed of the electromagnet generator cannot reach the set rotation speed, and the generated power cannot exceed the excitation power. It didn't work.

Therefore, there is a control technique for controlling the excitation current according to the number of rotations of the excitation coil in order to solve such a problem. In this control technique, by detecting the number of rotations of the excitation coil and supplying an excitation current appropriate to that number of rotations, it is possible to obtain an appropriate extraction output as a generator at that number of rotations.

Japanese Patent No. 4134582 JP-A-61-112536

However, the propeller's efficiency of converting wind speed into rotational energy varies depending on the ratio between the wind speed passing through the propeller and the peripheral speed of the propeller, which corresponds to the speed of the tip of the propeller. The ratio between the wind speed and the peripheral speed of the propeller is hereinafter referred to as the peripheral speed ratio.

Even if the wind speed is the same, the torque and power that can be generated by the propeller change depending on the rotation speed (=peripheral speed ratio). In other words, at each wind speed there is an optimum propeller speed for that wind speed.

Here, since the generated power is the square of the voltage, the higher the number of revolutions, the larger the amount of power generated by the square. Therefore, it can be seen that the amount of power generated is small and the efficiency is low, especially at low rotation speeds.

As for the wind power generator as a whole, an output obtained by multiplying the mechanical output of the propeller by the efficiency of the generator is obtained. Therefore, it is possible to generate power efficiently by setting the propeller rotation speed to the optimum for the wind speed and rotating at the highest possible speed.

Normally, small wind power generators perform electromagnetic brake control during strong winds. For this reason, it is common to make the torque generated by the generator larger than the torque generated by the propeller at any given rotation speed.

In that case, if the above-mentioned control technology is adopted and excitation control is performed to obtain the optimum extraction output of the generator, the rotation speed will be the locus where the torque generated by the propeller and the torque generated by the generator are equal. will be traced.

As a result, since the generated torque of the generator is large, the rotation speed becomes lower than the optimum rotation speed determined by the peripheral speed ratio of the propeller, and wind speed cannot be efficiently converted into rotational energy. Furthermore, since the number of revolutions is low, the efficiency of the generator is also poor, and the output of the generator at that time is a low output value.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and aims to obtain a power generator capable of converting wind or water energy into electric power more efficiently than conventional power generators. aim.

The power generator according to the present invention includes a propeller section that converts wind or water energy into rotational energy, an exciting coil section that generates a magnetic field by applying an electric current and rotates by being coupled to the propeller section, and an exciting coil section that is adjacent to the propeller section. an electromagnet generator having a generating coil unit that generates power according to changes in the magnetic field of the exciting coil unit; a rectifying unit that converts AC power generated from the generating coil unit into DC power; a power storage unit to be charged; an excitation unit that uses the power storage unit as a power supply to supply excitation power to the excitation coil unit; a rotation detection unit that detects the rotation speed of the propeller unit from the rotation speed of the excitation coil unit; Based on the obtained propeller rotation speed, the excitation coil section is controlled so that the electromagnetic generator generates a torque equivalent to the propeller torque that can be generated in a preset range with good propeller efficiency. a control unit that controls the excitation power to the first propeller characteristic corresponding to the relationship between the rotation speed of the propeller unit and the mechanical output at each wind speed, as preprocessing for controlling the excitation power, and A second propeller characteristic corresponding to the relationship between the number of revolutions of the propeller section and the torque at each wind speed is acquired in advance, and in the first propeller characteristic, the number of revolutions of the propeller section at which the mechanical output reaches the maximum point for each wind speed is determined as follows: In the second propeller characteristic, the torque corresponding to the rotation speed of the propeller at which the mechanical output reaches the maximum point is obtained for each wind speed. By obtaining in advance the excitation current that can generate torque corresponding to the rotation speed by actual measurement or simulation, the excitation current suitable for the rotation speed of the propeller section can be specified, and when controlling only the excitation section, preprocessing Rotation of the propeller obtained from the rotation detection unit using the relationship between the rotation speed of the propeller at which the mechanical output reaches the maximum point and the excitation current for generating the torque corresponding to the rotation speed specified by The excitation current corresponding to the number is specified, and the excitation power to the excitation coil section is controlled so as to flow the specified excitation current .

ADVANTAGE OF THE INVENTION According to this invention, compared with the conventional power generator, the power generator which can convert the energy of a wind or water into electric power efficiently can be obtained.

1 is a block diagram showing the configuration of a power generator according to Embodiment 1 of the present invention; FIG. FIG. 4 is a characteristic diagram showing the relationship between propeller rotation speed and mechanical output for each wind speed, and an example of operating points at each wind speed in the first embodiment of the present invention. FIG. 4 is a characteristic diagram showing the relationship between propeller rotation speed and torque for each wind speed and examples of operating points at each wind speed in Embodiment 1 of the present invention. FIG. 4 is an explanatory diagram showing an example of output characteristics and efficiency characteristics with respect to the number of revolutions of the generator in Embodiment 1 of the present invention; FIG. 10 is a diagram plotting the optimum excitation current specified in consideration of over-rotation prevention with respect to the propeller rotation speed in the second embodiment of the present invention. FIG. 10 is a characteristic diagram showing an example of operating points at each wind speed when the relationship between the propeller rotation speed and the mechanical output and the over-rotation prevention excitation control are executed for each wind speed in Embodiment 2 of the present invention. . FIG. 9 is a characteristic diagram showing the relationship between propeller rotation speed and torque for each wind speed, and an example of operating points at each wind speed when over-rotation prevention excitation control is executed in Embodiment 2 of the present invention. FIG. 4 is a block diagram showing the configuration of a power generation device according to Embodiment 4 of the present invention; FIG. 10 is a block diagram showing the configuration of a power generator according to Embodiment 5 of the present invention; FIG. 11 is a configuration diagram of a PWM voltage control circuit applied to a power generator according to Embodiment 6 of the present invention; FIG. 11 is a configuration diagram of a DC voltage variable control circuit applied to a power generator according to Embodiment 7 of the present invention;

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the power generator of the present invention will be described below with reference to the drawings.

Embodiment 1.
First, the configuration of the power generator according to Embodiment 1 will be described. FIG. 1 is a block diagram showing the configuration of a power generator according to Embodiment 1 of the present invention. The power generation section 1 has a power generation coil section 1a and an excitation coil section 1b. The generating coil portion 1a and the exciting coil portion 1b are arranged close to each other. The generating coil portion 1a and the exciting coil portion 1b are, for example, coaxially provided in a nested state.

The exciting coil portion 1b is coupled to a rotating portion 2 composed of a propeller for wind power generation, and rotates together with the rotating portion 2. As shown in FIG. The rotating part 2 corresponds to a propeller part. Further, the excitation coil portion 1b generates a magnetic field by being supplied with excitation power from the excitation portion 5. As shown in FIG.

On the other hand, the generating coil portion 1a is fixed. The generating coil portion 1a generates an alternating voltage due to the magnetic flux change due to the rotation of the magnetic field generated by the exciting coil portion 1b. Here, an electromagnet generator is composed of a power generation section 1 having a power generation coil section 1a and an excitation coil section 1b, and a rotating section 2 corresponding to a propeller section.

The rectifying unit 3 rectifies the AC voltage generated by the power generation coil unit 1 a to convert it into a DC voltage, and charges the power storage unit 4 . That is, the rectifying section 3 converts the AC power generated from the generating coil section 1a into DC power. The excitation unit 5 supplies excitation power to the excitation coil unit 1b using the power storage unit 4 as a power source, thereby exciting the excitation coil unit 1b.

The rotation detection unit 6 detects the number of rotations of the excitation coil unit 1b. The control unit 10 controls the excitation power from the excitation unit 5 according to the number of revolutions from the rotation detection unit 6 . The control unit 10 is composed of, for example, a processor and memory, or a computer composed of digital circuits.

A control unit 10 that controls excitation power determines an appropriate excitation power corresponding to the propeller rotation speed according to the rotation speed input from the rotation detection unit 6 and controls the excitation unit 5 .

Next, the excitation control performed in the power generator according to the first embodiment having the configuration shown in FIG. will be described in detail. In the following description, the control technique for controlling the excitation current based on the number of revolutions of the excitation coil is referred to as conventional excitation control.

FIG. 2 is a characteristic diagram showing the relationship between the propeller rotation speed and the mechanical output for each wind speed, and an example of operating points at each wind speed in Embodiment 1 of the present invention. FIG. 3 is a characteristic diagram showing the relationship between propeller rotation speed and torque for each wind speed, and an example of operating points at each wind speed in Embodiment 1 of the present invention.

The characteristic examples of FIGS. 2 and 3 are for the same propeller. Further, in FIGS. 2 and 3, the trajectory of the operating point when the conventional excitation control is adopted is plotted with ▪ marks, and the trajectory of the operating point when the excitation control according to the first embodiment is adopted. is plotted with ●.

From these FIGS. 2 and 3, it can be seen that even if the wind speed is the same, the torque and output that can be generated by the propeller change depending on the rotation speed (=peripheral speed ratio). In other words, at each wind speed, there is an "optimal propeller rotation number for each wind speed" corresponding to the mountain portion of the graph.

On the other hand, the following formula (1) expresses the principle of power generation.
Generated voltage E=BLV (1)
E: Generated voltage [V]
B: Magnetic flux density [Wb/m2]
L: wire length [m]
V: Velocity [m/s]

In the above equation (1), B×V corresponds to the amount of change in magnetic flux, and L corresponds to the number of turns of the coil. From the above equation (1), the generator is a system that generates a voltage according to the magnetic force change due to the number of revolutions and the number of turns of the coil. Here, since the generated power is the square of the voltage, the higher the number of revolutions, the larger the amount of power generated by the square.

FIG. 4 is an explanatory diagram showing an example of output characteristics and efficiency characteristics with respect to the number of revolutions of the generator in Embodiment 1 of the present invention. As can be seen from FIG. 4, the power generator generates a small amount of power and has poor efficiency, especially at low rotation speeds.

As for the wind power generator as a whole, the output obtained by multiplying the mechanical output of the propeller shown in FIG. 2 by the efficiency of the power generator shown in FIG. 4 is obtained. Therefore, it is possible to generate power efficiently by setting the propeller rotation speed to the optimum for the wind speed and rotating at the highest possible speed.

Normally, small wind power generators perform electromagnetic brake control during strong winds. For this reason, it is common to make the torque generated by the generator larger than the torque generated by the propeller at any given rotation speed.

In that case, if the conventional excitation control is performed to obtain the optimum extraction output of the generator, the rotation speed becomes equal between the torque generated by the propeller and the torque generated by the generator, as indicated by the ▪ mark in FIG. follow the trajectory.

As a result, since the generated torque of the generator is large, the rotation speed becomes lower than the optimum rotation speed determined by the peripheral speed ratio of the propeller, and wind speed cannot be efficiently converted into rotational energy. Furthermore, since the number of revolutions was low, the efficiency of the generator was also poor, and the output of the generator at that time followed the locus indicated by the ▪ mark in FIG. 2, resulting in a low output value.

Therefore, the excitation control according to the first embodiment is devised as follows in order to be able to convert the wind power into electric power more efficiently than the conventional excitation control.

Consider the case where the excitation current vs. torque characteristic corresponding to each rotation speed of the generator connected to the propeller is acquired in advance. In this case, in the power generator according to the first embodiment, the optimum rotation speed at which the rotation speed output at the peripheral speed ratio of the propeller is maximized with respect to the wind speed, that is, the mechanical output is the maximum value in FIG. The exciting current is controlled so that the generator generates a torque equivalent to the propeller torque generated at the rotation speed of . It should be noted that the "rotational speed at which the mechanical output reaches its maximum value" is an example of a preset range in which the propeller efficiency is good, and the "maximum value" does not necessarily have to be adopted.

With such control, the required torque at each revolution of the generator is balanced with the torque that produces the maximum mechanical output of the propeller for each wind speed. As a result, the generator to which the propeller is connected can always be stabilized at the optimum speed for each wind speed.

That is, as indicated by the trajectories of ● marks in FIGS. 2 and 3, the maximum output can be generated for any wind speed of the propeller. As a result, it is possible to control the power generator so that it is on the high-speed rotation side with good efficiency, thereby enabling optimum power generation.

Also, by performing such control, it is possible to always obtain the highest propeller efficiency. Therefore, the power generator according to the first embodiment generates power with the minimum required torque even at low rotation speed, and can maintain the optimum rotation speed without waste according to the wind speed.

Specifically, as preprocessing for realizing such excitation control, necessary data is acquired in advance by the following procedure. First, as shown in FIGS. 2 and 3, propeller characteristics corresponding to the relationship between rotation speed and mechanical output at each wind speed and the relationship between rotation speed and torque at each wind speed are obtained.

Next, as shown in FIG. 2, the point of maximum mechanical output at each wind speed is plotted as ●. Further, the rotational speed values corresponding to the ● marks in FIG. 2 are plotted as ● marks on the data for each wind speed in FIG. 3 . From the results of such plotting, the torque at the rotational speed of the maximum mechanical output point for each wind speed plotted in FIG. 2 can be obtained.

Next, the excitation current that allows the generator to generate the necessary torque for the propeller at the rotation speed indicated by the ● mark in FIG. 3 is obtained by actual measurement or simulation. As a result, it is possible to specify the optimum excitation current for the propeller rotation speed.

The control unit 10 issues a command to the excitation unit 5 to apply an excitation current that is optimum for the propeller rotation speed specified based on the rotation speed obtained from the rotation detection unit 6 . By executing such excitation control, the control unit 10 can converge the rotation speed to the maximum propeller mechanical output at the current wind speed. Furthermore, since the control unit 10 can set the power generator output to the high-rotation side with good efficiency, the maximum output of the wind power generator can be obtained.

Since the conventional power generator employs a control technique that obtains the maximum output of the generator, the rotation speed is stabilized to follow the trajectory indicated by the ▪ mark in FIGS. 2 and 3 . For example, when the wind speed is 11 m/s, the torque converges to around 0.95 Nm from FIG. 3 and stabilizes at 450 rpm, and the output that can be generated at that time is 50 W from FIG.

On the other hand, in the power generator according to the first embodiment, excitation control is performed to obtain the maximum output of the propeller, and the rotation speed is stabilized to follow the trajectory indicated by ● in FIGS. 2 and 3 . For example, when the wind speed is 11 m/s, as shown in FIG. 3, the torque is stabilized at 1300 rpm near 2.1 Nm, and the output that can be generated at that time is 280W.

From this, it can be seen that the power generator according to Embodiment 1 can efficiently convert wind power into electric power over a wider rotation speed range than the conventional power generator.

Embodiment 2.
As in the first embodiment, when the optimum excitation control is performed for the propeller characteristics, the rotation speed increases as the wind speed increases. As a result, there is a risk that the propeller will be destroyed, especially when the number of revolutions exceeds the rotational resistance of the propeller. Therefore, in the second embodiment, a technique for preventing such propeller breakage will be described.

The control unit 10 according to the second embodiment applies torque greater than the propeller torque when the propeller output is the best when the rotational speed of the propeller is equal to or higher than the upper limit rotational speed, which is a predetermined propeller rotational speed. The excitation unit 5 is controlled so that the power generation unit 1 generates.

Specifically, the control section 10 controls the excitation section 5 so as to increase the excitation current to the excitation coil section 1b. As a result, the power generator according to the second embodiment can prevent the propeller from over-rotating, and can generate power at the maximum propeller speed or less even in strong winds.

For example, a case where the upper limit rotation speed is 1100 rpm will be described. FIG. 5 is a diagram plotting the optimum excitation current determined in consideration of over-rotation prevention with respect to the propeller rotation speed in the second embodiment of the present invention. FIG. 5 shows overspeed prevention excitation control 1 and overspeed prevention excitation control 2 as examples of excitation control for preventing overspeed.

When the overspeed prevention excitation control 1 is executed, the control unit 10 controls the excitation current to be rapidly increased to the maximum excitation current when the propeller rotation speed reaches or exceeds the upper limit rotation speed of 1100 rpm. . As a result, power generation can be continued while preventing the propeller rotation speed from increasing to 1100 rpm or more.

In addition, the control unit 10, instead of the over-rotation prevention excitation control 1, when there is a possibility that impact stress, etc., will occur on the rotation system because a sudden increase in the excitation current causes a sudden change in torque. Excessive rotation prevention excitation control 2 can be executed at this time.

When executing the overspeed prevention excitation control 2, the control unit 10 executes excitation control in which the excitation current is proportionally or curvedly increased gradually according to the rotation speed up to a certain rotation speed greater than 1100 rpm. do. FIG. 5 illustrates a case where the control unit 10 performs excitation control that gradually increases the excitation current between 1100 rpm and 1300 rpm proportionally or curvilinearly according to the rotation speed.

As a result, sudden fluctuations in torque can be suppressed, impact stress on the rotating system can be suppressed, and power generation can be continued while suppressing excessive rotation. It can easily maintain high rotation as a machine.

FIG. 6 shows the relationship between the propeller rotation speed and the mechanical output for each wind speed, and an example of operating points at each wind speed when over-rotation prevention excitation control is executed in Embodiment 2 of the present invention. It is a characteristic diagram. FIG. 7 shows the relationship between propeller rotation speed and torque for each wind speed, and an example of operating points at each wind speed when over-rotation prevention excitation control is executed in the second embodiment of the present invention. 1 is a characteristic diagram.

In FIG. 6 and FIG. 7, the excitation control executed in the range of rotation speed below 1100 rpm is plotted as ● mark, and the overspeed prevention excitation control 1 executed in the rotation speed range of 1100 rpm or more is plotted as * mark. , and the overspeed prevention excitation control 2, which is executed in the region where the rotation speed is 1100 rpm or more, is plotted as ▴ marks.

As shown in FIGS. 6 and 7, when the number of revolutions is less than 1100 rpm, the excitation control shown in the first embodiment is performed. On the other hand, when the number of revolutions reaches 1100 rpm or more, overspeed prevention excitation control 1 or overspeed prevention excitation control 2 is performed.

By adopting this type of over-rotation prevention excitation control, it is possible to continue power generation while maintaining the mechanical rotation speed of the propeller from low to high wind speeds up to the limit of the mechanical rotation speed of the propeller. can.

In addition, at the time of excessive rotation, measures such as an electromagnetic brake are usually taken to lower the rotation speed. In this case, since the excessive rotation region is reached at low wind speeds, the condition of using the brake frequently occurs even with wind speeds in the practical range, and there is a possibility that a situation in which it is difficult to generate power will occur.

On the other hand, in the second embodiment, by performing overspeed prevention excitation control at the upper limit speed or more, it is possible to prevent overspeed and to generate power at high wind speeds. As a result, it is possible to reduce the timing at which the electromagnetic brake is applied when the engine is over-rotating, and to increase the amount of power generated as a whole.

Embodiment 3.
In conventional excitation control, optimum excitation control is performed for the generator. That is, in the conventional excitation control, even when the actual output of the propeller is insufficient to generate power, the optimum excitation control is performed for the generator. As a result, the generator generates a torque larger than the torque generated by the propeller, which reduces the rotation speed and, in the worst case, stops the rotation.

Once the propeller stops, the torque that can be generated when it is not rotating is smaller than the torque that can be obtained when it is rotating, and when it resumes rotating, it requires a rotation starting torque larger than that for normal rotation. Therefore, a high wind speed is required to restart the rotation. Therefore, in the third embodiment, a technique for solving such problems will be described.

In the power generator according to the third embodiment, as shown in FIG. 6 above, the number of revolutions of the propeller is lower than the predetermined lower limit number of revolutions (lower limit number of revolutions=400 rpm in FIG. 6). At this time, the control section 10 performs excitation control such that the excitation coil section 1b is not excited. As a result, it is possible to eliminate the cogging torque generated by executing the excitation at 400 rpm or less, and realize the control to suppress the useless reduction in rotation speed.

Note that the lower limit rotation speed is set to be equal to or higher than the minimum rotation speed at which power generation is possible, which is individually determined by each generator. As a result, without stopping the rotation, when the wind speed rises next time, it is possible to immediately generate rotation following the wind speed, making it possible to earn a large amount of power generation.

Embodiment 4.
The magnetic field created by the current is determined by multiplying the current value by the number of coil turns. Therefore, when controlling the excitation power, the excitation current is generally changed. Also, the exciting coil is made of a conductor such as copper, and the DC resistance value of the coil has the property of changing with temperature due to the temperature characteristics of the conductor. A resistance value having temperature characteristics is represented by the following equation (2).
Rt=R20(1+α20(t−20))[Ω] (2)
Rt: Resistance value at temperature t°C [Ω]
R20: Resistance value of copper wire at temperature of 20°C [Ω]
α20: Temperature coefficient of copper wire resistance [1/°C]

As in Embodiments 1 to 3, when excitation control is performed according to the number of rotations, the coil resistance changes depending on the temperature of the excitation coil as shown in the above equation (2), and the target excitation current can be applied. Sometimes you can't.

Therefore, in the third embodiment, as a method for solving this problem, a case where a temperature detection unit for measuring the temperature of the excitation coil is added and excitation is performed in consideration of the change in the resistance value due to temperature will be described.

FIG. 8 is a block diagram showing the configuration of a power generator according to Embodiment 4 of the present invention. The block diagram shown in FIG. 8 further includes a temperature detection unit 7 in addition to the block diagram of FIG. 1 in the first embodiment.

The temperature detector 7 detects the temperature of the exciting coil portion 1b. The control unit 10 performs excitation control in consideration of the temperature of the excitation coil unit 1b detected by the temperature detection unit 7. FIG. As a result, the control unit 10 performs temperature compensation in consideration of the temperature change of the excitation coil unit 1b based on the temperature detection result by the temperature detection unit 7, and performs excitation control so that a target excitation current corresponding to the rotation speed is supplied. can be executed.

Specifically, the control unit 10 can set the target excitation current as in the following equation (3).
Im=V/Rt (3)
Im: target current [A]
V: excitation voltage [V]
Rt: Resistance value at temperature t°C [Ω]

Embodiment 5.
In the fourth embodiment, a case has been described in which a target excitation current is supplied by performing excitation according to changes in resistance due to temperature. In contrast, in the fifth embodiment, a case will be described in which the actual excitation current is measured and fed back, and control is performed to match the excitation current according to the rotational speed.

FIG. 9 is a block diagram showing the configuration of a power generator according to Embodiment 5 of the present invention. In the block diagram shown in FIG. 9, an excitation current monitor section 8 is added to the block diagram of FIG. 1 in the first embodiment.

The excitation current monitor section 8 is connected between the excitation section 5 and the excitation coil section 1b. The exciting current monitor unit 8 monitors the exciting current value when the exciting voltage is applied to the exciting coil unit 1b by the exciting unit 5 as a feedback value. As a result, the control section 10 can control the excitation section 5 in accordance with the actual excitation power obtained from the detection result of the excitation current monitor section 8 .

By performing such current feedback, more detailed excitation control can be performed. Normally, there is a method of matching the target current Im by PI control, but it is possible to match the target current Im by simply applying the excitation voltage obtained by the following formula (4).
Va=Vr+Rr×(Im−Ir) (4)
Va: Excitation voltage after correction [V]
Vr: previous excitation voltage [V]
Rr: previous excitation coil resistance [Ω]
(The value of the above formula (2) or the calculated value as Rr=Vr/Ir)
Ir: Excitation current [A] measured by excitation current monitor unit 8 when Vr excitation voltage is applied
Im: target excitation current [A]

Embodiment 6.
In the sixth embodiment, a case of applying pulse width modulation (PWM) voltage control as a specific method of variably controlling the excitation voltage will be described. A general PWM method performs PWM control of the following formula (5) when the power supply voltage is V in order to apply the target excitation voltage Vm.
Duty=Vm/V (5)
Duty: ON duty of PWM control
Vm: Target excitation voltage [V]
V: Power supply voltage for excitation [V]

FIG. 10 is a configuration diagram of a PWM voltage control circuit applied to a power generator according to Embodiment 6 of the present invention. A PWM voltage control circuit corresponds to a pulse width modulation voltage control circuit. The excitation unit 5 according to the sixth embodiment is configured as a PWM voltage control circuit that converts the voltage of the power storage unit 4 into a desired voltage and supplies the voltage to the excitation coil unit 1b. When PWM control is employed as a method for controlling excitation power, a circuit configuration such as that shown in FIG.

Embodiment 7.
In the seventh embodiment, as a specific method of variably controlling the excitation voltage, a case of applying DC voltage variable control will be described. FIG. 11 is a configuration diagram of a DC voltage variable control circuit applied to a power generator according to Embodiment 7 of the present invention. The excitation unit 5 according to the seventh embodiment is configured as a DC voltage variable control circuit that converts the voltage of the power storage unit 4 into a desired voltage and supplies the voltage to the excitation coil unit 1b.

The control unit 10 controls the DC voltage control circuit shown in FIG. 11, adjusts the DC voltage using the power storage unit 4 as a power source, and controls the excitation power. As a result, fluctuations in cogging torque can be reduced, and controllability that facilitates rotation can be obtained.

In the above description, the case of converting wind energy into rotational energy was mainly described, but the present invention is not limited to wind energy. The present invention is equally applicable to converting water energy into rotational energy instead of wind energy.

1 power generation unit 1a power generation coil unit 1b excitation coil unit 2 rotation unit (propeller unit) 3 rectification unit 4 electricity storage unit 5 excitation unit 6 rotation detection unit 7 temperature detection unit 8 excitation current monitor unit 10 control unit, 11 flywheel diode, 12 switching element.

Claims (7)

a propeller section that converts wind or water energy into rotational energy;
an exciting coil unit that generates a magnetic field by applying a current and rotates by being coupled to the propeller unit; and a generating coil unit that is arranged in proximity to the exciting coil unit and generates power according to changes in the magnetic field of the exciting coil unit; an electromagnet generator having
a rectification unit that converts AC power generated from the power generation coil unit into DC power;
a power storage unit charged with the DC power of the rectifying unit;
an excitation unit that supplies excitation power to the excitation coil unit using the electricity storage unit as a power supply;
a rotation detection unit that detects the rotation speed of the propeller unit from the rotation speed of the exciting coil unit;
Based on the number of revolutions of the propeller unit obtained from the rotation detection unit, only the excitation unit is operated so that the electromagnetic generator generates a torque equivalent to the propeller torque that can be generated in a preset region where the propeller efficiency is good. A control unit that controls the excitation power to the excitation coil unit by controlling
The control unit
As a pretreatment for controlling the excitation power,
A first propeller characteristic corresponding to the relationship between the rotation speed of the propeller unit and mechanical output at each wind speed, and a second propeller characteristic corresponding to the relationship between the rotation speed and torque of the propeller unit at each wind speed are obtained in advance. death,
In the first propeller characteristic, the number of rotations of the propeller portion at which the mechanical output reaches the maximum point for each wind speed is obtained as the number of rotations in the region of good propeller efficiency;
In the second propeller characteristic, obtain a torque corresponding to the rotation speed of the propeller portion at which the mechanical output reaches the maximum point for each wind speed,
The excitation current suitable for the rotation speed of the propeller portion is specified in advance by obtaining in advance by actual measurement or simulation the excitation current that can generate the torque corresponding to the rotation speed of the propeller portion at which the mechanical output reaches the maximum point. ,
When controlling only the excitation section , the number of rotations of the propeller section at which the mechanical output reaches the maximum point specified by the preprocessing and the excitation current for generating the torque corresponding to the rotation number. Using the correspondence relationship, an exciting current corresponding to the number of rotations of the propeller unit obtained from the rotation detection unit is specified, and exciting power to the exciting coil unit is controlled so as to flow the specified exciting current. . When the number of revolutions of the propeller section obtained from the rotation detection section reaches or exceeds a predetermined upper limit number of revolutions, the control section generates a rotation speed of the propeller section in a region where the propeller efficiency is good. The power generator according to claim 1, wherein the exciting power to the exciting coil unit is controlled by controlling the exciting unit so that the electromagnetic generator generates a torque larger than the propeller torque that can be generated. 3. The control unit does not excite the excitation coil unit when the number of revolutions of the propeller unit obtained from the rotation detection unit is equal to or less than a predetermined lower limit number of revolutions. The power generator according to . further comprising a temperature detection unit that detects the temperature of the excitation coil unit,
The power generator according to any one of claims 1 to 3, wherein the control section controls the excitation section according to the excitation power obtained by performing temperature compensation according to the temperature detection result of the temperature detection section. further comprising an exciting current monitor unit for monitoring an exciting current when an exciting voltage is applied to the exciting coil unit,
The control unit controls the excitation unit according to the actual excitation power obtained from the detection result of the excitation current monitor unit.
The power generator according to any one of claims 1 to 4. The excitation unit has a pulse width modulation voltage control circuit by PWM control as a method for controlling the excitation power,
The power generator according to any one of claims 1 to 5. The excitation unit has a DC voltage control circuit as a method for controlling the excitation power,
The power generator according to any one of claims 1 to 5.

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