JP2021035180A - Wind power generator - Google Patents

Abstract

To improve the utilization factor of a wind power generator.SOLUTION: A dynamo 20 includes: a field winding 28 which is provided on a rotor mechanically connected to the revolving shaft of blades 5; an armature winding 27 provided on a stator; and a rectifier 29 connected between the armature winding 27 and an output terminal 22. An output current control circuit 40 is connected between an output terminal 22 and a power storage element 30. The output current control circuit 40 is configured to control the step-up ratio of a second DC voltage Vout of an output node Nout, electrically connected to the power storage element 30, to a first DC voltage Vb of an input node Nin electrically connected to the output terminal 22. The power storage element 30 is charged by the generated power of the dynamo 20 converted into the second DC voltage Vout.SELECTED DRAWING: Figure 1

Description

The present invention relates to a wind power generator.

Conventionally, a rotor connected to a blade shaft, a field winding provided on the rotor, an armature winding provided on the stator, and a rectifier that full-wave rectifies the output power of the armature winding have been used. The generator provided is used in the wind power generator. Many wind turbines with such a configuration are small-scale, and the generated power is generally stored in a storage battery connected to the output of the rectifier.

In such a wind power generator, the exciting current (field current) flowing through the field winding is controlled in order to adjust the output voltage. According to Japanese Patent Application Laid-Open No. 2003-284393 (Patent Document 1), the supply of the field current is started when the rotation speed of the blade shaft becomes equal to or higher than the first value, while the field current is started at the rotation speed lower than that. Controls that do not supply current are described. By this control, it is possible to provide a wind power generation device capable of reducing the load on the stopped blade and easily starting the rotation.

Japanese Unexamined Patent Publication No. 2003-284393

In the type of wind power generator described in Patent Document 1, a storage battery is connected to the output of the rectifier. Therefore, the generator can be in the power generation state only when the generator is operating in a state where a voltage exceeding the voltage of the storage battery can be generated at the output of the rectifier. For this reason, there is concern that power generation opportunities will be limited.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to operate a generator in a power generation state without generating a voltage exceeding the voltage of a storage battery at the output of a rectifier. By doing so, it is possible to improve the equipment utilization rate of the wind power generator.

In one aspect of the present invention, the wind power generator comprises a generator, a power storage element, an output voltage control circuit, an exciting current control circuit, and a controller that controls the operation of the output voltage control circuit and the exciting current control circuit. Be prepared. The generator is connected between the field winding provided on the rotor mechanically connected to the rotating shaft of the propeller, the armature winding provided on the stator, the armature winding and the output terminal. Has a rectifier. The power storage element is charged by the DC power output by the generator to the output terminal. The output voltage control circuit is connected between the output terminal and the power storage element. The output voltage control circuit controls the boost ratio of the second DC voltage of the output node electrically connected to the power storage element to the first DC voltage of the input node electrically connected to the output terminal. It is composed. The exciting current control circuit is electrically connected to the power storage element and the field winding to control the exciting current supplied to the field winding. The controller includes a rotation speed detection unit, an output voltage control unit, and an exciting current control unit. The rotation speed detection unit detects the rotation speed of the rotation shaft. The output voltage control unit determines the output voltage command value of the generator according to the rotation speed detected by the rotation speed detection unit, and at the same time, the output voltage control circuit of the output voltage control circuit so that the first DC voltage matches the output voltage command value. Control the boost ratio. The exciting current control unit determines the exciting current command value according to the rotation speed detected by the rotation speed detecting unit, and controls the operation of the exciting current control circuit so that the exciting current matches the exciting current command value.

According to the present invention, even when the DC voltage output from the rectifier to the output terminal is lower than the DC voltage of the power storage element, the power storage element can be charged with the DC power from the generator by boosting the output voltage control circuit. .. As a result, the capacity factor of the wind power generator can be improved by expanding the operating range in which the generator can generate power.

It is the schematic which shows the structure of the wind power generation apparatus which concerns on Embodiment 1 of this invention. It is a circuit diagram which shows the structure of the electric circuit part of the wind power generation apparatus shown in FIG. This is an example of a characteristic diagram of the number of revolutions of the wind turbine and the torque. It is a characteristic diagram of the rotation speed-machine output of the wind turbine having the characteristics shown in FIG. It is an electric equivalent circuit diagram of the stator of the generator shown in FIG. It is a block diagram explaining the control configuration example by the generator control part shown in FIG. It is a block diagram explaining the structural example of the output voltage control part shown in FIG. It is a conceptual diagram which shows an example of the relationship between the rotation speed of a generator and the command value of an output voltage. It is a block diagram explaining the structural example of the exciting current control part shown in FIG. It is a block diagram explaining the structural example of the torque calculation part used in the wind power generation apparatus which concerns on Embodiment 2. FIG. It is a conceptual diagram which shows an example of the characteristic of mutual inductance with respect to an exciting current and an output current. It is a circuit diagram which shows the structure of the electric circuit part of the wind power generation apparatus which concerns on Embodiment 3 of this invention. FIG. 5 is a functional block diagram illustrating a configuration example of a generator control unit in the wind power generation device according to the third embodiment. It is a circuit diagram explaining the structural example of the mode determination part shown in FIG. FIG. 3 is a block diagram illustrating a configuration example of the output voltage control unit shown in FIG. It is a block diagram explaining the structural example of the exciting current control part shown in FIG. It is a block diagram explaining the structural example of the armature current calculation part shown in FIG. It is a block diagram explaining the structural example of the torque calculation part shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings will be designated by the same reference numerals, and the explanations will not be repeated in principle.

Embodiment 1.
FIG. 1 is a schematic view showing a configuration of a wind power generation device according to a first embodiment of the present invention.

With reference to FIG. 1, the wind power generation device 10 according to the first embodiment includes a generator 20, a power storage element 30, an output voltage control circuit 40, an exciting current control circuit 50, and a generator control unit 60. Be prepared.

The generator 20 is provided on terminals 21 to 25, a three-phase armature winding 27 provided on a stator (not shown), and a rotor mechanically connected to a propeller 5 (not shown). The field winding 28 and the rectifier 29 are included. The propeller 5 is arranged so as to rotate in response to the wind.

The generator 20 can be configured by, for example, an alternator for an automobile. The terminal 21 corresponds to a P terminal that outputs an AC voltage having a frequency corresponding to the rotation speed of the rotor. The terminal 23 corresponds to the E terminal for grounding, and the terminal 22 corresponds to the B terminal to which the DC voltage obtained by the power generation of the generator 20 is output. The terminals 24 and 25 are connected to one end and the other end of the field winding 28. The terminal 22 (B terminal) corresponds to an embodiment of the “output terminal” of the generator.

The rectifier 29 is composed of a diode bridge that performs three-phase full-wave rectification. One end of the three-phase armature winding 27 is connected to the AC side (three-phase) of the diode bridge, respectively. The other ends of the three-phase armature winding 27 are connected to each other at a neutral point. One end of one phase of the three-phase armature winding 27 is further connected to the terminal 21 (P terminal).

The DC side of the diode bridge constituting the rectifier 29 is connected to the terminal 22 and the terminal 23. In the generator 20, the three-phase AC voltage generated in the armature winding 27 due to the rotation of the propeller 5 is rectified by the rectifier 29, and DC power (that is, DC voltage and DC current) is output from the terminal 22. ..

The input side of the output voltage control circuit 40 is connected to the terminal 22. The output side of the output voltage control circuit 40 is electrically connected to the power storage element 30. The power storage element 30 can be composed of, for example, a secondary battery such as a lead storage battery, a capacitor, or the like.

The input side of the exciting current control circuit 50 is electrically connected to the power storage element 30, and the output side is connected to the terminals 24 and 25 of the generator 20. The exciting current control circuit 50 uses the output voltage of the power storage element 30 to generate an exciting current If supplied to the field winding 28.

The generator control unit 60 operates by supplying electric power from the power storage element 30 to control each element of the wind power generation device 10. In FIG. 1, the generator control unit 60 generates control signals for the output voltage control circuit 40 and the exciting current control circuit 50 as part of the control function.

The generator control unit 60 can be configured to include a CPU (Central Processing Unit), a memory, an input / output interface, and an internal power supply circuit (not shown). The internal power supply circuit uses the electric power from the power storage element 30 to generate a control power source. Various data such as a control program, data obtained by calculation, a detected value, and a command value can be stored in the memory. The CPU can read the program and data required for the desired calculation from the memory and execute the control calculation described later. The generator control unit 60 corresponds to an embodiment of the “controller”.

The power storage element 30 is also used as a power source for an external load (not shown), for example, lighting and a sensor. That is, the power storage element 30 is charged by the electric power generated by the generator 20 via the output voltage control circuit 40, the control power source of the wind power generation device 10 itself, the power source of the exciting current If flowing through the field winding 28, and It also functions as a power source for the above external load. Therefore, in reality, the power storage element 30 is charged by the power generated by subtracting the power consumption as the power source from the power generated by the generator 20. Although not shown, the power storage element 30 is provided with a voltage, current, and temperature detector, a protection circuit, and a power supply circuit for the load.

FIG. 2 is a circuit diagram showing a configuration of an electric circuit portion of the wind power generation device 10 shown in FIG. FIG. 2 mainly shows a configuration example of the output voltage control circuit 40 and the exciting current control circuit 50.

With reference to FIG. 2, the output voltage control circuit 40 can be configured by a step-up DC / DC converter generally called a chopper. For example, the output voltage control circuit 40 includes smoothing capacitors 41 and 42, a diode 43, a switching element 44, and a reactor 45. The switching element 44 can be composed of a self-extinguishing semiconductor element typified by a MOSFET (Metal-Oxide-semiconductor Field-Effect Transistor), which can be turned on and off according to a control signal. The switching element 44 is turned on and off according to the gate signal SGb from the generator control unit 60.

The smoothing capacitor 41 is connected between the input node Nin, which is electrically connected to the terminal 22, and the node Ng. The node Ng has the same potential as the terminal 23 of the generator 20 (for example, the ground potential). The smoothing capacitor 42 is connected between the output node Nout, which is electrically connected to the power storage element 30, and the node Ng. The input node Nin and the output node Nout correspond to the "input node" and the "output node" of the output voltage control circuit 40, respectively.

The switching element 44 is connected between the node Nm1 and the node Ng. The switching element 44 is turned on and off according to the gate signal SGb from the generator control unit 60. The diode 43 is connected between the node Nm1 and the output node Nout. The anode of the diode 43 is connected to the node Nm1 and the cathode is connected to the output node Nout. That is, the diode 43 passes the current from the node Nm1 to the output node Nout, while blocking the current from the output node Nout to the node Nm1. The reactor 45 is connected between the input node Nin and the node Nm1.

In the output voltage control circuit 40, the DC voltage Vb of the input node Nin is defined as the input voltage, the DC current Ib input to the input node Nin is defined as the input current, and the DC voltage Vout of the output node Nout is defined as the output voltage. Although not shown, detectors for DC current Ib, DC voltage Vb, and output voltage Vout are arranged. The values detected by these detectors are input to the generator control unit 60.

In the configuration example of FIG. 2, since the terminal 22 is directly connected to the input node Nin, the DC voltage Vb and the DC current Ib correspond to the output voltage and the output current of the generator 20, respectively. The output current of the generator 20 corresponds to the armature current flowing through the armature winding 27 of the generator 20. Therefore, it is possible to detect the output voltage and the output current of the generator 20 by detecting the DC voltage Vb and the DC current Ib in the output voltage control circuit 40. Therefore, in the following, the DC voltage Vb and the DC current Ib are also treated as the output voltage and the output current of the generator 20. That is, the product of the DC voltage Vb and the DC current Ib corresponds to the generated power output from the generator 20.

In the output voltage control circuit 40 (step-up DC / DC converter), when the switching element 44 is on, energy is stored in the reactor 45 by the current flowing from the input node Nin to the reactor 45. When the switching element 44 is turned off, the energy stored in the reactor 45 is released to the output node Out via the diode 43. As a result, a voltage higher than that of the input node Nin can be generated in the output node Nout (Vout ≧ Vb).

In the boost chopper, when the duty ratio Db defined by the ratio of the on-time of the switching element 44 in the unit time is used, Db = between the DC voltage (input voltage) Vb and the DC voltage (output voltage) Vout. It is known that a 1- (Vb / Vout) relationship is established. Therefore, the voltage ratio represented by the equation (1) can be controlled by on / off control of the switching element 44.

1-Db = (Vb / Vout) ... (1)
In the formula (1), since 0 <(1-Db) ≦ 1, the output voltage control circuit 40 can operate within the range of (Vb / Vout) ≦ 1, that is, Vout ≧ Vb. Therefore, it is understood that the boost ratio (Vout / Vb) of the output voltage Vout to the input voltage Vb can be controlled by changing (1-Db) corresponding to the off time ratio of the switching element 44.

The exciting current control circuit 50 can be configured by a step-down DC / DC converter (step-down chopper) that uses the field winding 28 of the generator 20 as a reactor. For example, the exciting current control circuit 50 includes a smoothing capacitor 46, a diode 47, and a switching element 48. Like the switching element 44, the switching element 48 is composed of a self-extinguishing semiconductor element.

The smoothing capacitor 46 is connected between the node Nf connected to the terminal 24 and the node Ng. The smoothing capacitor 46 is charged by the output voltage of the power storage element 30. The switching element 48 is connected between the node Nm2 and the node Ng connected to the terminal 25. The switching element 44 is turned on and off according to the gate signal SGf from the generator control unit 60. The diode 47 is connected between the node Nm2 and the node Nf. The anode of the diode 47 is electrically connected to the node Nm2 and the cathode is connected to the node Nf. That is, the diode 47 passes the current from the node Nm2 (terminal 25) to the node Nf, while blocking the current from the node Nf to the node Nm2.

The field winding 28 is electrically connected between the terminals 24 and 25 inside the generator 20. The exciting current control circuit 50 operates as a step-down chopper in which the DC voltage of the smoothing capacitor 46 is used as the input voltage and the voltage generated in the field winding 28 by the exciting current If is used as the output voltage. Since the smoothing capacitor 46 is charged by the power storage element 30, the voltage of the smoothing capacitor 46 is equivalent to the voltage of the smoothing capacitor 42 (output voltage Vout). Although not shown, a detector for the exciting current If is arranged, and the detected value of the exciting current If is also input to the generator control unit 60.

During the ON period of the switching element 48, the input voltage of the smoothing capacitor 46 is used, and the node Nf passes through the terminal 24, the field winding 28, the terminal 25 (node Nm2), and the switching element 48. The exciting current If is supplied by the path leading to Ng with energy storage in the field winding 28.

On the other hand, during the off period of the switching element 48, the input voltage of the smoothing capacitor 46 is not supplied, and the return of the node Nf, the terminal 24, the field winding 28, the terminal 25 (node Nm2), the diode 47, and the node Nf. Due to the path, the exciting current If continues to flow due to the energy stored in the field winding 28.

Therefore, when the duty ratio Df defined by the ratio of the on-time of the switching element 48 in a unit time is used, the voltage (Vout) of the smoothing capacitor 46, the DC voltage Vf generated in the field winding 28, and the duty ratio The relationship of Vf = Vout · Df is established between Df. When the electric resistance value Rf of the field winding 28 is used, Vf = Rf · If, so the exciting current If is expressed by the equation (2).

If = (Vout / Rf) · Df ... (2)
That is, the exciting current control circuit 50 can control the exciting current If by the duty ratio Df of the switching element 48.

A diode 51 may be further connected between the power storage element 30 (node Nb) and the generator control unit 60. The diode 51 has an anode connected to the node Nb and a cathode connected to the generator control unit 60. As a result, the current from the generator control unit 60 to the power storage element 30 is cut off.

Similarly, a diode 52 may be further connected between the exciting current control circuit 50 (node Nf) and the power storage element 30 (node Nb). The diode 52 has an anode connected to the node Nb and a cathode connected to the node Nf. As a result, the current from the exciting current control circuit 50 to the power storage element 30 is cut off.

Further, a diode 53 may be further connected between the output voltage control circuit 40 (output node Nout) and the power storage element 30 (node Nb). The diode 53 has an anode connected to the output node Nout and a cathode connected to the node Nb. As a result, the current from the power storage element 30 to the output voltage control circuit 40 is cut off.

By arranging the diodes 51 to 53, it is possible to fix the current direction between the power storage element 30, the output voltage control circuit 40, the exciting current control circuit 50, and the generator control unit 60. The arrangement of the diodes 51 to 53 can be omitted. It is also possible to further connect a diode between the terminal 22 of the generator 20 and the output voltage control circuit 40 in the direction of cutting off the current from the output voltage control circuit 40 to the terminal 22.

Next, the characteristics of the wind power generator will be described with reference to FIGS. 3 and 4.

FIG. 3 is an example of a characteristic diagram of the rotation speed-torque of the wind turbine.

The horizontal axis of FIG. 3 shows the rotation speed N [r / min] of the wind turbine, and the vertical axis shows the torque T [Nm] generated in the wind turbine. In the wind power generator 10 of FIG. 1, the rotation speed and torque of the propeller 5 correspond to the horizontal axis and the vertical axis of FIG. 3, respectively.

Under a constant wind speed, the generated torque of a wind turbine is determined when the number of revolutions is determined. In FIG. 3, a curve showing the relationship between the number of revolutions and the torque is drawn for each wind speed.

From FIG. 3, when the wind speed is constant, the torque T also increases as the rotation speed N of the wind turbine increases, but when the rotation speed N further increases beyond the maximum point (maximum torque point), the torque T becomes. It decreases as the number of revolutions N increases.

The torque generated by the wind turbine (maximum torque) at the maximum torque point at each wind speed increases as the wind speed increases, and the rotation speed N at which the maximum torque is generated also increases as the wind speed increases.

When the wind turbine has a characteristic that torque To is generated when the rotation speed is No in the reference wind speed Vo, the rotation speed N and torque T of the wind turbine at an arbitrary wind speed V are expressed by the following equations (3) and (3). It can be expressed in 4) respectively.

N = No. (V / Vo) ... (3)
T = To ・ (V / Vo) ^ 2… (4)
From equation (3), it can be seen that the number of revolutions N is proportional to the wind speed, and from equation (4), the torque T is proportional to the square of the wind speed. By deriving the relationship between the rotation speed N and the torque T from the equations (3) and (2), the equation (5) can be obtained. From the equation (5), the torque T is the square of the rotation speed N. It can be confirmed that they are proportional.

T = To ・ (N / No) ^ 2… (5)
FIG. 4 is a characteristic diagram of the rotation speed-mechanical output of the wind turbine having the rotation speed-torque characteristic shown in FIG. The horizontal axis of FIG. 4 shows the same rotation speed N [r / min] as in FIG. 3, and the vertical axis shows the machine output P [W]. The machine output P is represented by the product of the machine angular velocity ω and the torque T. Since the angular velocity ω with respect to the rotation speed N is represented by ω = (N / 60) · 2.π, the machine output P [W] can be expressed by the following equation (6).

P = (N / 60), 2, π, T ... (6)
Further, the relationship between the mechanical output Po at the reference wind speed Vo and the mechanical output P at an arbitrary wind speed V can be expressed by the following equation (7). From equation (7), it can be confirmed from equation (5) that the mechanical output P is proportional to the cube of the wind speed.

P = Po ・ (V / Vo) ^ 3… (7)
By deriving the relationship between the rotation speed N and the machine output P from the equations (3) and (7), the equation (8) can be obtained. From equation (8), it can be confirmed that the machine output is proportional to the cube of the rotation speed N.

P = Po ・ (N / No) ^ 3… (8)
Also in FIG. 4, when the wind speed is constant, the mechanical output P increases as the rotation speed N of the wind turbine increases, but when the rotation speed N further increases beyond the maximum point (maximum output point), the mechanical output increases. P decreases as the number of revolutions N increases.

The mechanical output (maximum output) of the wind turbine at the maximum output point at each wind speed increases as the wind speed increases, and the rotation speed N at which the maximum output is generated also increases as the wind speed increases. In FIG. 4, the maximum output line 210 corresponding to the set of the maximum output points at each wind speed is further shown. The maximum output line 210 is a set of rotation speeds at which the mechanical output is maximized at each wind speed.

The maximum output line 210 corresponds to a functional expression when the rotation speed No and the machine output Po corresponding to the operating point at which the machine output P is maximized are substituted for the equation (8). By substituting the rotation speed No. and the torque To at this time into the equation (7), the maximum output line 210 can be drawn also on FIG.

Therefore, if the rotation speed-torque characteristics of the wind turbine can be grasped as shown in FIG. 3, the generator 20 should be operated at the operating point (combination of rotation speed N and generated torque T) on the maximum output line 210. Therefore, even if the wind speed cannot be known, the machine output P can be taken out to the maximum according to the wind speed.

Next, a method of controlling the operation of the generator 20 so that the generator 20 generates a desired torque will be described.

In general, a winding field synchronous motor can control the output by adjusting the reactive current component flowing through the armature winding. In the present embodiment, as shown in FIG. 1, the generator 20 has an armature winding 27 and a field winding 28, and includes a synchronous generator with a field winding. However, a rectifier 29 is connected to the output terminal. Therefore, in the generator 20, the fundamental wave component of the reactive current does not flow in the armature winding. Therefore, the generator 20 of FIG. 1 in which the rectifier 29 is connected to the output side of the synchronous generator can be regarded as a separately excited DC generator.

Generally, in a separately excited DC generator, the armature current Ia, the exciting current If of the field winding, and the mutual inductance Laf between the armature and the field winding (hereinafter, also simply referred to as "mutual inductance Laf"). The internally induced voltage Ea is expressed by the equation (9) and the generated torque Te is expressed by the equation (10) with respect to the mechanical angular velocity ω.

Ea = Laf ・ If ・ ω… (9)
Te = Laf ・ If ・ Ia… (10)
Therefore, the mutual inductance Laf can be calculated from the equation (10) by measuring the exciting current If, the armature current Ia, and the generated torque Te by the characteristic test of the generator 20. In the first embodiment, as understood from the circuit configuration of FIG. 2, the armature current Ia of the generator 20 corresponds to the direct current Ib input from the terminal 22 to the output voltage control circuit 40. Therefore, when the generator 20 is in operation, the generated torque can be calculated according to the equation (10) by using the mutual inductance Laf calculated in advance in the characteristic test and the detected values of the exciting current If and the input current Ib.

FIG. 5 shows an electrically equivalent circuit of a stator of a generator 20 equipped with an armature winding 27 and a rectifier 29.

With reference to FIG. 5, the stator equivalent circuit is described in the form of a three-phase AC circuit converted into a DC circuit. Therefore, in FIG. 5, the inductance La of the armature winding 27 and the armature winding resistance Ra are also converted to direct current. Further, Vd in FIG. 5 indicates a forward voltage drop caused by the diode of the rectifier 29, and the voltage of the terminal 22 is equivalent to the DC voltage Vb of the output voltage control circuit 40 described with reference to FIG.

In this equivalent circuit, the following equation (11) holds for the internally induced voltage Ea.

Ea = La · dIb / dt + Ra · Ib + 2 · Vd + Vb ... (11)
Due to the action of the diode in the rectifier 29, in the equation (11), Ib> 0 when Ea-2 · Vd-Vb> 0, while Ib> 0 when Ea-2 · Vd-Vb ≦ 0. , Ib = 0. Further, the direct current Ib changes according to the voltage difference between Ea and Vb. By using the equations (9) to (11), the DC voltage Vb and the exciting current If are controlled according to the mechanical angular velocity ω so that the DC current Ib and the generated torque Te become desired values. The machine 20 can be operated.

Here, in the equations (9) to (11), the generator 20 is treated as a DC generator, but in reality, the generator 20 is a synchronous generator having a pole logarithm of p. Therefore, the ripple voltage generated when the three-phase AC is full-wave rectified to DC is included in the actual output voltage from the generator 20 (that is, the DC voltage Vb). The frequency fe of the ripple voltage can be expressed by the following equation (12).

fe = ω / (2 ・ π) ・ p = N / 60 ・ p… (12)
In the present embodiment, the DC voltage Vb and the exciting current control circuit 50 are used so that the generator 20 is operated with the desired DC current Ib (corresponding to the armature current Ia) and the generated torque Te. The exciting current If is controlled. The method for controlling the DC voltage Vb and the exciting current If, and the method for determining the desired values of the DC current Ib and the generated torque Te are not limited, but for example, the following control can be applied. it can. In this embodiment, the propeller 5 and the rotors of the generator 20 are directly connected to each other, and the description will proceed assuming that the rotation speeds of both are the same value.

Assuming that the desired value of the torque generated by the wind turbine Te (for example, the value for setting the operating point on the maximum output line 210 in FIG. 3) is Te = T1 at the rotation speed N1, the generator 20 is rotated at the rotation speed N1. And when operating at the operating point of the torque T1, the larger the generated powers Vb and Ib and the smaller the loss due to the exciting current If, the larger the amount of charge to the power storage element 30. Therefore, since there is a correlation between the DC voltage Vb, the DC current Ib, and the exciting current If, it cannot be easily determined, but in general, the DC voltage Vb is larger and the exciting current If and the DC current are larger. Operation under conditions where Ib is smaller is advantageous in terms of efficiency.

As shown by the equation (5), it is desirable that the wind turbine is operated with a torque proportional to the square of the rotation speed. Therefore, in the region where the rotation speed N is small, the exciting current If and the output current Ib are reduced to reduce the generated torque Te. Further, as can be understood from the equation (9), the internally induced voltage Ea is proportional to the mechanical angular velocity ω (that is, the rotation speed N). In the region where the rotation speed N is small, the internally induced voltage Ea is lowered because the exciting current If is reduced as described above. In order to obtain the generated power under this condition, it is necessary to control the DC voltage Vb low by the output voltage control circuit 40.

Therefore, in the present embodiment, the output voltage from the generator 20 (that is, the DC voltage Vb on the input side of the output voltage control circuit 40) is controlled to the above-mentioned appropriate value for obtaining the generated power. The output voltage control circuit 40 operates. Further, under this state, the exciting current control circuit 50 is set so that the generated torque Te of the generator 20 (actually, the calculated value Te of the generated torque Te) becomes the above-mentioned desired value T1 (Teh = T1). Controls the exciting current If.

FIG. 6 is a block diagram illustrating an example of a control configuration by the generator control unit 60. The function of each block described in the block diagram including FIG. 6 is realized by, for example, software processing by the CPU included in the generator control unit 60 executing a program stored in advance. Can be done. Alternatively, at least a part of each function can be realized by hardware such as an electronic circuit.

With reference to FIG. 6, the generator control unit 60 includes a rotation speed detection value generation unit 62, an output voltage control unit 64, and an exciting current control unit 66.

The AC voltage Vp output from the terminal 21 (P terminal) is input to the rotation speed detection value generation unit 62. The electric angular frequency of the rotor of the generator 20 can be obtained from the AC voltage Vp, and the rotation speed N of the propeller 5 and the generator 20 can be calculated from the electric angular frequency and the number of pole pairs p of the generator 20. Hereinafter, the rotation speed detection value generated by the rotation speed detection value generation unit 62 is also referred to as a rotation speed N. As described above, in the present embodiment, the rotation speed N indicates the rotation speed of both the generator 20 and the propeller 5 (wind turbine).

The output voltage control unit 64 generates a gate signal SGb of the switching element 44 of the output voltage control circuit 40 based on the detected values of the rotation speed N of the propeller 5 and the DC voltage Vb.

FIG. 7 is a block diagram illustrating a configuration example of the output voltage control unit 64.

With reference to FIG. 7, the output voltage control unit 64 includes an output voltage command value generation unit 71, a subtractor 72, a voltage controller 73, a comparator 74, and a NOT gate 75.

The output voltage command value generation unit 71 generates an output voltage command value Vbref, which is a command value of the DC voltage Vb corresponding to the output voltage of the generator 20, based on the rotation speed N detected by the rotation speed detection value generation unit 62. To do.

FIG. 8 is a conceptual diagram showing an example of the relationship between the rotation speed N and the output voltage command value Vbref.

With reference to FIG. 8, basically, the output voltage command value Vbref is set to increase as the rotation speed N increases. However, in the region where the rotation speed N is small, the output voltage command value Vbref is preferably a constant value so that the DC voltage Vb does not become too small. Further, the output voltage command value Vbref is set with the output voltage Vout (detection value) of the output voltage control circuit 40 at that time as an upper limit value.

The output voltage command value generation unit 71 takes the rotation speed N detected by the rotation speed detection value generation unit 62 as an input according to the relationship between the rotation speed N and the output voltage command value Vbref shown in FIG. 8, and outputs the output voltage. It can be configured by an arithmetic expression or a look-up table that outputs the command value Vbref.

As can be understood from the equation (10), what is directly related to the generated torque Te is the direct current Ib corresponding to the armature current of the generator 20. Therefore, when the operating point (N, Te) of the generator 20 is determined, the output voltage command value generation unit 71 issues an output voltage command to a value such that the generator 20 can output a desirable DC current Ib at the operating point. It is also possible to determine the value Vbref. That is, the output voltage command value Vbref is not limited to being determined according to the equation (11), and can be determined by measuring the output characteristics according to the operating point in advance. Alternatively, the output voltage command value Vbref can be determined according to an arithmetic expression other than the equation (11).

With reference to FIG. 7 again, the subtractor 72 subtracts the DC voltage Vb (detection value) from the output voltage command value Vbref to calculate the voltage deviation ΔVb. The voltage deviation ΔVb is input to the voltage controller 73.

The voltage controller 73 is composed of, for example, a proportional integration controller, and calculates the duty ratio of the switching element 44 in the output voltage control circuit 40 so that the DC voltage Vb matches the output voltage command value Vbref. The initial value of the integration term in the proportional integration control can be, for example, Vb / Vout. Here, "the DC voltage Vb matches the output voltage command value Vbref" is not limited to the case where the two exactly match, and also includes the case where the DC voltage Vb approaches (follows) the output voltage command value Vbref. It shall be. Hereinafter, the same shall apply to the description of “matching” regarding control in the present specification.

The voltage controller 73 outputs a control amount (1-Db) indicating the duty ratio of the switching element 44 of the output voltage control circuit 40 during the off period within the range of 0 <(1-Db) ≦ 1.0. As shown in the equation (1), since the output voltage control circuit 40 has a relationship of 1-Db = Vb / Vout, the DC voltage Vb is output by increasing or decreasing the voltage ratio (Vb / Vout). The control amount (1-Db) can be set so as to match the voltage command value Vbref.

The comparator 74 compares the control amount (1-Db) from the voltage controller 73 with the carrier wave CW. The carrier wave CW is composed of, for example, a triangular wave that periodically repeats rising and falling within the range of 0 ≦ CW ≦ 1.0. The frequency of the carrier (triangular wave) CW corresponds to the switching frequency of the switching element 44.

When (1-Db) is larger than the carrier wave CW, the comparator 74 outputs a logical high level (hereinafter, also simply referred to as “H level”), and conversely, (1-Db) is the carrier wave. When it is smaller than CW, a logical low level (hereinafter, also simply referred to as “L level”) is output. As a result, the comparator 74 outputs a pulse signal indicating the control amount (1-Db) and the comparison result of the carrier wave CW.

The NOT gate 75 outputs an inverted signal of the pulse signal from the comparator 74 as a gate signal SGb. The gate signal SGb is transmitted to the switching element 44. During the H level period of the gate signal SGb, the switching element 44 is controlled to the on state, and during the L level period of the gate signal SGb, the switching element 44 is controlled to the off state.

It is also possible to input the duty ratio Db obtained from the control amount (1-Db) to the comparator 74. In this case, the output (pulse signal) of the comparator 74 can be used as it is as the gate signal SGb without arranging the NOT gate 75.

With reference to FIG. 6 again, the exciting current control unit 66 generates the gate signal SGf of the switching element 48 of the exciting current control circuit 50 based on the detected values of the rotation speed N, the exciting current If, and the direct current Ib. ..

FIG. 9 is a block diagram illustrating a configuration example of the exciting current control unit 66.

With reference to FIG. 9, the exciting current control unit 66 includes a torque command value generation unit 81, a torque calculation unit 82, subtractors 83, 85, a torque controller 84, a current controller 86, and a comparator 87.

The torque command value generation unit 81 generates the torque command value Teref of the generator 20 based on the rotation speed N detected by the rotation speed detection value generation unit 62. For example, the torque command value Teref is obtained from the rotation speed N so as to select the operating point on the maximum output line 210 shown in FIG. That is, the torque command value generation unit 81 inputs the rotation speed N and outputs the torque command value Teref according to the rotation speed-torque characteristic corresponding to the maximum output line 210 in FIG. It can be configured by a table.

It is also possible to set the torque command value Teref in the low rotation speed region to be smaller than the value on the maximum output line 210 in order to prevent stall at low wind speeds. Similarly, in order to prevent over-rotation at high wind speeds, it is possible to set the torque command value Teref in the high rotation speed region to be larger than the value on the maximum output line 210.

The detection value of the excitation current If output from the excitation current control circuit 50 and the detection value of the DC current Ib (corresponding to the output current of the generator 20) of the output voltage control circuit 40 are input to the torque calculation unit 82. .. The torque calculation unit 82 outputs the torque calculation value Theh according to the product of the mutual inductance Laf calculated in advance in the characteristic test and the detected values of the exciting current If and the input current Ib using the above equation (10).

The subtractor 83 calculates the torque deviation ΔTe by subtracting the torque calculation value Teh from the torque command value Teref. The torque deviation ΔTe is input to the torque controller 84.

The torque controller 84 is composed of, for example, a proportional integration controller, and the torque deviation ΔTe becomes zero, that is, the exciting current command value Ifref for controlling the torque calculation value Teh to match the torque command value Teref. Is output.

The subtractor 85 subtracts the exciting current If (detected value) from the exciting current command value Ifref to calculate the current deviation ΔIf. The current deviation ΔIf is input to the current controller 86.

The current controller 86 is composed of, for example, a proportional integration controller, and calculates the duty ratio of the switching element 48 in the exciting current control circuit 50 for the exciting current If to match the exciting current command value Ifref.

The current controller 86 outputs the duty ratio Df of the switching element 48 of the exciting current control circuit 50 during the on period within the range of 0 ≦ Df ≦ 1.0. As shown in the equation (2), since the exciting current control circuit 50 has a relationship of Df = If / (Vout / Rf), the duty ratio Df is increased for ΔIf> 0, while ΔIf. The duty ratio Df can be adjusted so as to decrease the duty ratio Df with respect to <0.

The comparator 87 compares the duty ratio Df from the current controller 86 with the carrier wave CW similar to that of the comparator 74, and outputs a gate signal SGf. The gate signal SGf is transmitted to the switching element 48. Therefore, the switching element 48 is controlled to be in the on state during the period when Df is larger than the carrier wave CW, while the switching element 48 is turned off during the period when Df is smaller than the carrier wave CW. Be controlled. The frequency of the carrier wave CW can be independently determined between the output voltage control circuit 40 and the exciting current control circuit 50.

In the example of FIG. 9, the exciting current command value Ifref was set by the torque controller 84, but directly according to the rotation speed N detected by the rotation speed detection value generation unit 62 without considering the torque control. , Excitation current command value Ifref may be set. This is because when the output voltage command value Vbref for the rotation speed N is determined based on the characteristics of the wind turbine (propeller 5) and the generator 20, the torque command value Teref is generated for a certain rotation speed N. This is because it is possible to uniquely determine the exciting current command value Ifref to be generated.

Further, in FIG. 6, an example of calculating the rotation speed detection value from the AC voltage Vp has been described, but it is also possible to arrange a sensor that directly detects the mechanical angle or the rotation speed of the rotor of the generator 20. .. In this case, the rotation speed detection value generation unit 62 can output the rotation speed detection value by using the output signal of the sensor. Also, regarding the DC voltage Vb, DC current Ib, and exciting current If, the sensors are arranged so as to detect the voltage or current at the point indicated by the arrow in FIG. 2, and the same detection value can be obtained. It is also possible to place the sensor in the place of. Alternatively, instead of directly detecting these voltages or currents, it is also possible to obtain them by calculation using other detected values and calculated values. Further, the output of each sensor (detector) can be input to a low-pass filter to remove harmonic components and noise, and then used for control.

As described above, in the wind power generator according to the first embodiment, the generator 20 having the field winding 28 and the rectifier 29 has an output voltage control circuit 40 and an exciting current controlled by the generator control unit 60. The control circuit 50 operates while controlling the DC voltage Vb and the exciting current Iff according to the output voltage command value Vbref and the exciting current command value Ifref.

In the wind power generator according to the first embodiment, by arranging the output voltage control circuit 40, the output voltage (DC voltage Vb) from the generator 20 can be boosted to charge the power storage element 30. As a result, the generator 20 can be operated in the power generation state even in a region where the rotation speed of the propeller 5 is low and the output voltage of the generator 20 is lower than the voltage of the power storage element 30. As a result, the capacity factor of the wind power generation device can be improved.

Further, regarding the exciting current command value Ifref, the torque determined according to the rotation speed N so that the generator 20 operates at the operating point set according to the rotation speed-torque characteristic of the wind turbine (propeller 5). It can be set so that torque control according to the command value Teref is realized. Similarly, the output voltage command value Vbref can be set so that the charging power to the power storage element 30 becomes large when the generator 20 outputs the torque according to the torque command value Teref corresponding to the rotation speed N. it can. Therefore, the wind power generator according to the first embodiment is particularly advantageous for operating the generator 20 at low rotation speed and low torque.

Further, in the wind power generation device according to the first embodiment, power is generated by setting an output voltage command value Vbref and a torque command value Teref (or an exciting current command value Ifref) corresponding to the rotation speed N of the generator 20. The torque generated by the machine 20 can be controlled. As a result, even if the wind speed is not detected, the generator 20 is operated at an operating point (for example, an operating point on the maximum output line 210 of FIGS. 3 and 4) in which the mechanical output of the wind turbine increases according to the actual wind speed. It is possible to generate electricity with high efficiency.

In addition, since the magnetic flux generated by the field winding 28 can be adjusted by changing the exciting current If, the torque command value proportional to the product of the exciting current If and the direct current Ib (corresponding to the output current of the generator 20). When setting the Teref, the degree of freedom in combining the exciting current If and the DC current Ib is increased. As a result, the combination of the exciting current If and the DC current Ib can be controlled so that the loss is reduced.

Further, since the exciting current If and the direct current Ib (output current of the generator 20) can be changed in a wide range, power can be generated even if the characteristics of the generator 20 are not designed exclusively for the connected wind turbine. It is possible to secure a wide area. For example, when a device such as an alternator for an automobile, which is normally used at a high speed, is applied to the generator 20 to configure a wind power generator according to the first embodiment, the generator 20 is operated at a low speed. In addition, it is possible to generate electricity with high efficiency.

Further, the generator 20 is regarded as a DC generator, and the armature obtained from the armature current Ia (corresponding to the DC current Ib), the exciting current If, and the generated torque Te obtained in advance in the characteristic test of the generator 20. By using the mutual inductance Laf between the field windings and the field windings, the torque calculation value Teh can be obtained from the detected values of the exciting current If and the DC current Ib. That is, torque control is possible without providing a torque detector.

As described above, the wind power generator according to the first embodiment can efficiently generate power in a wide wind speed range and charge the power storage element 30 according to the characteristics of the wind turbine and the generator 20.

Embodiment 2.
In the first embodiment, torque control is executed with the mutual inductance Laf between the armature and the field winding as a constant value. On the other hand, when an automobile alternator or the like is used as the generator 20, if power is generated in a wide rotation speed region including a low rotation speed region, there is a concern that the mutual inductance Laf will change significantly with respect to a change in the operating point. To.

Therefore, in the second embodiment, a modification of the torque calculation unit in the first embodiment will be described.

FIG. 10 is a block diagram illustrating a configuration example of the torque calculation unit 82 used in the wind power generation device according to the second embodiment. In the wind power generation device according to the second embodiment, the torque calculation unit 82 in the exciting current control unit 66 of FIG. 9 is configured according to FIG.

With reference to FIG. 10, the torque calculation unit 82 according to the second embodiment includes a mutual inductance calculation unit 88 and multipliers 89 and 90.

The mutual inductance calculation unit 88 generates the mutual inductance calculation value Lafh based on the detected values of the exciting current If and the DC current Ib.

FIG. 11 is a conceptual diagram showing an example of the characteristics of the mutual inductance Laf with respect to the exciting current If and the direct current Ib (corresponding to the armature current Ia). The characteristics of the mutual inductance Laf shown in FIG. 11 can also be obtained by a characteristic test of the generator 20.

In the characteristic example shown in FIG. 11, when the exciting current If is constant, the mutual inductance Laf decreases as the direct current Ib increases. Further, in the region where the direct current Ib is small and in the region where the direct current Ib is large, the slope (dLaf / dIb) in which the mutual inductance Laf changes with respect to the change in the direct current Ib is large, and in the intermediate region, the slope is small.

Further, when the exciting current If is different, the change characteristic of the mutual inductance Laf with respect to the direct current Ib changes significantly. In particular, it is understood that as the exciting current If increases, the slope (dLaf / dIb) of the mutual inductance Laf in the region where the direct current Ib is small increases.

The mutual inductance calculation unit 88 inputs the detected values of the direct current Ib and the exciting current If according to the characteristics of the mutual inductance Laf shown in FIG. 11, and outputs the mutual inductance calculation value Lafh. It can be configured by a lookup table.

Again, referring to FIG. 10, the multiplier 89 outputs a multiplication value of the mutual inductance calculation value Lafh by the mutual inductance calculation unit 88 and the exciting current If (detection value). The multiplication value corresponds to the magnetic flux generated by the field winding 28.

Further, the multiplier 90 outputs the multiplication value of the multiplication value (Lafh · If) output by the multiplier 89 and the direct current Ib corresponding to the armature current Ia as the torque calculation value Teh. Therefore, also in the second embodiment, the torque calculation value Tea is calculated according to the same equation (10) as in the first embodiment using the mutual inductance calculated value Lafh.

Since the configuration of the parts other than the torque calculation unit 82 of the wind power generation device according to the second embodiment is the same as that of the first embodiment, detailed description will not be repeated. Therefore, regarding the control of the exciting current If (exciting current control unit 66), the control calculation after the torque calculation value Teh is input to the subtractor 83 of FIG. 9 is the same as that of the first embodiment. Further, the control of the DC voltage Vb (output voltage control unit 64) is the same as that of the first embodiment.

As described above, in the wind power generator according to the second embodiment, the torque is not constant even when the mutual inductance Laf between the armature and the field winding is not a constant value but changes according to the exciting current If and the output current Ib. It is possible to secure the calculation accuracy.

As a result, in addition to the effects described in the first embodiment, even when the generator 20 has a characteristic that magnetic saturation cannot be ignored, torque control can be executed without providing a torque detector. The effect is produced. In particular, even when using a generator such as an alternator for automobiles whose torque does not increase in proportion to the armature current under constant excitation, it is possible to execute torque control without installing a torque detector. Become.

Embodiment 3.
FIG. 12 is a circuit diagram showing a configuration of an electric circuit portion of the wind power generation device 10 according to the third embodiment.

With reference to FIG. 12, in the configuration according to the third embodiment, a point where the switch 54 is arranged instead of the diode 53 and the diodes 56 to 58 are added as compared with the first embodiment (FIG. 2). The point of arrangement is different. Since the configuration of the other parts of FIG. 12 is the same as that of the first embodiment, detailed description of these common parts will not be repeated.

The diode 56 is connected between the terminal 22 of the generator 20 and the output voltage control circuit 40. The anode of the diode 56 is connected to the terminal 22, and the cathode is connected to the input node Nin of the output voltage control circuit 40. As a result, it is possible to reliably prevent the output current Ib of the generator 20 from being in the negative direction, that is, the current from flowing from the output voltage control circuit 40 to the terminal 22 (generator 20).

By arranging the diode 56, the input voltage of the output voltage control circuit (boost chopper) 40 is, strictly speaking, a value obtained by subtracting the voltage drop amount at the diode 56 from the voltage of the terminal 22. Therefore, in the third embodiment, the input voltage of the output voltage control circuit (boost chopper) 40 is expressed as the DC voltage Vb as in the first embodiment, while the voltage of the terminal 22 (that is, the output of the generator 20). Voltage) is also referred to as Vb *.

The diode 58 is connected between the terminal 22 of the generator 20 and the node Nf corresponding to the input node of the exciting current control circuit 50. Since the diode 58 has an anode connected to the terminal 22 and a cathode connected to the node Nf, the diode 58 is connected in the forward direction from the terminal 22 of the generator 20 to the exciting current control circuit 50. The diode 58 corresponds to one embodiment of the "second diode". Further, as in the first embodiment, the diode 52 connected between the power storage element 30 (node Nb) and the node Nf with the direction from the power storage element 30 to the exciting current control circuit 50 as the forward direction is "first. Corresponds to one embodiment of "diode".

The diode 57 and the switch 55 are connected in series between the terminal 22 of the generator 20 and the node Nb connected to the power storage element 30 in order to form a bypass path of the output voltage control circuit 40. The switch 54 is connected to the path between the output node Nout and the node Nb of the output voltage control circuit 40. The diode 57 is connected with the direction from the terminal 22 to the node Nb as the forward direction.

In the example of FIG. 12, the switches 54 and 55 are composed of MOSFETs like the switching elements 44 and 48, but if the on and off can be controlled, the switch 54 is made by another semiconductor element, a relay, or the like. And 55 can also be configured. The switches 54 and 55 are turned on and off by a control signal from the generator control unit 60. The switch 54 corresponds to an embodiment of the "first switch", and the switch 55 corresponds to an embodiment of the "second switch".

In the configuration of the third embodiment, although not shown, the DC voltage VBAT of the node Nb and the detector of the input current IBAT to the node Nb are further arranged. The values detected by these detectors are input to the generator control unit 60. The detector of the input current IBAT is arranged between the switches 54 and 55 and the node Nb so as not to detect the current flowing out from the node Nb via the diode 51 or 52.

As described in the first embodiment, by arranging the output voltage control circuit 40, even when the rotation speed of the generator 20 is low and the induced voltage is low, the output voltage of the generator 20 is boosted to increase the power storage element 30. It becomes possible to charge. On the other hand, when the rotation speed of the generator 20 increases and the induced voltage becomes sufficiently high, the increase in the output voltage of the generator 20 eliminates the need for boosting in the output voltage control circuit 40. In this case, the output voltage control unit 64 (FIG. 7) controls the duty ratio Db = 0, and the switching element 44 is fixed in the off state. However, even when boosting is not required, the output current Ib of the generator 20 flows through the reactor 45 and the diode 43 to charge the power storage element 30, so that there is a concern that power loss may occur in the reactor 45 and the diode 43. To.

Therefore, in the configuration of the third embodiment, the switch 54 is turned off when boosting is not required, that is, when the output voltage (Vb *) of the generator 20 is higher than the DC voltage (VBAT) of the node Nb. At the same time, the switch 55 is turned on. As a result, the power storage element 30 can be charged by the output current of the generator 20 by bypassing the output voltage control circuit 40. As a result, the power loss can be reduced as compared with the case of passing through the reactor 45 and the diode 43.

On the other hand, when boosting is required, that is, when the output voltage (Vb *) of the generator 20 is lower than the DC voltage VBAT (node Nb), the switch 54 is turned on to obtain the first embodiment. Similarly, the power storage element 30 can be charged by the output voltage Vout boosted by the output voltage control circuit 40.

Further, due to the arrangement of the diode 58, when the voltage of the terminal 22 (output voltage of the generator 20) is higher than the voltage of the node Nf, the direct feeding path from the terminal 22 to the exciting current control circuit 50 is a diode. Formed by 58.

The voltage of the node Nf is equal to or less than the voltage of the node Nb, that is, the DC voltage VBAT of the power storage element 30. Therefore, when the output voltage (Vb *) of the generator 20 is higher than the DC voltage VBAT, the diode 58 is turned on, and the exciting current is supplied directly from the terminal 22 without passing through the power storage element 30. If can be generated.

On the other hand, when the voltage of the node Nf, which is equivalent to the DC voltage VBAT of the power storage element 30, is higher than the output voltage of the generator 20 (DC voltage of the terminal 22), the diode 58 is turned off. In this case, as in the first embodiment, the exciting current If is generated by the power supply from the power storage element 30 via the diode 52.

FIG. 13 is a block diagram illustrating a configuration example of a generator control unit in the wind power generation device according to the third embodiment.

With reference to FIG. 13, in the wind power generation device according to the third embodiment, the generator control unit 60 has the same rotation speed detection value generation unit 62 as in FIG. 6 (the first embodiment) and the third embodiment. It has a mode determination unit 67, an output voltage control unit 68, and an exciting current control unit 69.

The mode determination unit 67 generates mode signals MDH and MDL based on the rotation speed N detected by the rotation speed detection value generation unit 62.

FIG. 14 shows a configuration example of the mode determination unit 67.

With reference to FIG. 14, the mode determination unit 67 includes a hysteresis comparator 91 and a NOT gate 92. The rotation speed N detected by the rotation speed detection value generation unit 62 is input to the positive side of the hysteresis comparator 91. On the other hand, the threshold value Nth for mode determination is input to the negative side of the hysteresis comparator 91.

The threshold value Nth is a determination value as to whether or not boosting by the output voltage control circuit 40 is necessary, that is, whether or not the power storage element 30 can be directly charged by the output voltage of the generator 20. The threshold value Nth can be set to a predetermined fixed value, but it is preferable to set the threshold value Nth variably in conjunction with the DC voltage VBAT of the power storage element 30. Specifically, it is preferable that the threshold value Nth is set high when the DC voltage VBAT rises, and the threshold value Nth is also set low when the DC voltage VBAT decreases.

The output signal of the hysteresis comparator 91 is basically H level when N> Nth, while it is L level when N <Nth. As is known, when the output signal of the hysteresis comparator 91 changes from the H level to the L level, the rotation speed N is compared with a value lower than the threshold value Nth. Similarly, when the output signal of the hysteresis comparator 91 changes from the L level to the H level, the rotation speed N is compared with a value higher than the threshold value Nth.

The NOT gate 92 inverts the output signal of the hysteresis comparator 91 and outputs a mode signal MDL. On the other hand, the output signal of the hysteresis comparator 91 is output from the mode determination unit 67 as a mode signal MDH. Therefore, in the region where the rotation speed N is higher than the threshold value Nth, the mode signal MDH is set to the H level, while the mode signal MDL is set to the L level. On the contrary, in the region where the rotation speed N is lower than the threshold value Nth, the mode signal MDL is set to the H level, while the mode signal MDH is set to the L level.

The mode signal MDL is used as an on / off control signal for the switch 54, and the mode signal MDH is used as an on / off control signal for the switch 55. That is, in the region of N> Nth, the switch 55 is turned on while the switch 54 is turned off. On the contrary, in the region of N <Nth, the switch 54 is turned on while the switch 55 is turned off.

When switching the on / off of the switches 54 and 55, it is preferable to provide an overlap of the on periods of both in order to prevent disconnection due to both of the switches 54 and 55 being turned off.

With reference to FIG. 13 again, the output voltage control unit 68 includes the rotation speed N detected by the rotation speed detection value generation unit 62, the detection value of the input voltage (DC voltage Vb) of the output voltage control circuit, and the mode signal. Based on the MDH, the gate signal SGb of the switching element 44 (output voltage control circuit 40) is generated.

FIG. 15 is a block diagram illustrating a configuration example of the output voltage control unit 68.

With reference to FIG. 15, the output voltage control unit 68 further includes an AND gate 76 in addition to the configuration of the output voltage control unit 64 shown in FIG. Further, instead of the voltage controller 73 in FIG. 7, a voltage controller 77 into which the mode signal MDL is further input is arranged. As described above, the mode signal MDL is set to H level at low rotation (N <Nth) when boosting is required, while it is set to L level at high rotation (N <Nth) where boosting is not required. To.

The voltage controller 77 has, in addition to the function of the voltage controller 73 of FIG. 7, a stop function and a reset function of the integral calculation linked to the mode signal MDL. Specifically, during the H level period of the mode signal MDL (that is, when boosting is required), the voltage controller 77 operates in the same manner as the voltage controller 73 of FIG.

On the other hand, the voltage controller 77 resets the value of the integration term to 1 when the mode signal MDL changes from the H level to the L level. Since the voltage controller 77 outputs a control amount (1-Db) like the voltage controller 73, the above reset value corresponds to the duty ratio Db = 0. Further, the voltage controller 77 stops the integration operation during the L level period of the mode signal MDL, and restarts the integration operation with the reset value as the initial value when the mode signal MDL changes from the L level to the H level.

The AND gate 76 outputs the AND (logical product) calculation result of the output signal of the NOT gate 75 and the mode signal MDL as the gate signal SGb of the switching element 44. Therefore, the gate signal SGb is set in the same manner as in the first embodiment during the H level period of the mode signal MDL, that is, at the time of low rotation (N <Nth) where boosting is required.

On the other hand, during the L level period of the mode signal MDL, that is, at high rotation (N> Nth) where boosting is not required, the gate signal SGb is fixed at the L level. As a result, the switching element 44 of the output voltage control circuit 40 is fixed in the off state.

From the above, at the time of low rotation where boosting is required, the power storage element 30 is charged by the DC voltage Vout in which the output voltage control circuit 40 boosts the output voltage of the generator 20 as in the first embodiment. On the other hand, at high speeds where boosting is not required, the switch 54 and the switching element 44 are turned off, and the switch 55 is turned on to form a bypass path for the output voltage control circuit 40, thereby suppressing power loss. , The power storage element 30 can be directly charged by the output voltage of the generator 20.

With reference to FIG. 13 again, the exciting current control unit 69 detects the rotation speed N detected by the rotation speed detection value generation unit 62, the exciting current If, the direct current Ib, and the input current IBAT to the node Nb. The gate signal SGf of the switching element 48 of the exciting current control circuit 50 is generated by receiving the value and the mode signals MDL and MDH.

FIG. 16 shows a block diagram showing a configuration example of the exciting current control unit 69.

With reference to FIG. 16, the exciting current control unit 69 is different from the exciting current control unit 66 shown in FIG. 9 in that it further includes an armature current calculation unit 93.

In the circuit configuration of the third embodiment (FIG. 12), a current path is generated by the diodes 57 and 58. Therefore, as in the configuration of the first embodiment (FIG. 2), the direct current of the input node Nin of the output voltage control circuit 40 The current Ib cannot be regarded as the armature current Ia in the equation (10). Therefore, in order to execute the torque calculation according to the equation (10), in the third embodiment, the armature current Ia is obtained by the estimation calculation by the armature current calculation unit 93.

The armature current calculation unit 93 is calculated by the DC current Ib, the exciting current If, the detection value of the input current IBAT to the node Nb, the mode signals MDL, MDH, and the current controller 86 of the output voltage control circuit 40. In response to the duty ratio Df (switching element 48), the armature current calculated value Iah is output.

In the circuit configuration of the third embodiment (FIG. 12), when the voltage (Vb *) of the terminal 22 of the generator 20 is lower than the DC voltage VBAT and the diodes 57 and 58 do not turn on, the circuit configuration is the same as that of the first embodiment. Similarly, the armature current Ia of the generator 20 is output from the terminal 22, and the entire amount becomes the DC current Ib at the input node Nin of the output voltage control circuit 40. Therefore, during the period when the mode signal MDL is set to the H level, the armature current calculated value Iah = Ib (detection value) can be set.

On the other hand, when the voltage (Vb *) of the terminal 22 becomes higher than the DC voltage VBAT, a current path is formed by the diodes 57 and 58. Therefore, during the period when the mode signal MDH is set to the H level, the armature current Ia output from the terminal 22 bypasses the output voltage control circuit 40 and passes through the diode 57 and the diode 58. It is indicated by the sum of the current input to the exciting current control circuit 50.

The current passing through the diode 57 when the switch 55 is turned on can be detected as the input current IBAT to the node Nb. On the other hand, since the output current of the exciting current control circuit 50 corresponding to the step-down chopper is the exciting current If, the input current Iin of the exciting current control circuit 50 corresponds to the product of the duty ratio Df of the switching element 48 and the exciting current If. To do.

Therefore, in the H level period of the mode signal MDH, the armature current calculated value Iah can be obtained according to the following equation (13). That is, the input current Iin to the exciting current control circuit 50 at the node Nf corresponds to the "first input current", while the input current IBAT corresponds to the "second input current".

Iah = If · Df + IBAT… (13)
FIG. 17 is a block diagram showing a configuration example of the armature current calculation unit 93.

With reference to FIG. 17, the armature current calculation unit 93 includes multipliers 94, 96, 98 and adders 95, 97. Further, in FIG. 17, each of the mode signals MDL and MDH is set to "0" in the L level period and "1" in the H level period.

The multiplier 94 outputs a multiplier value Iao of the mode signal MDL and the input current Ib (detection value). The multiplier 96 outputs a multiplication value of the exciting current If (detection value) and the duty ratio Df. The adder 97 outputs an added value of the input current IBAT (detected value) and the output value of the multiplier 96. The multiplier 98 outputs the multiplication value Iag of the output value of the adder 97 and the mode signal MDH.

In the H level period of the mode signal MDL (that is, the L level period of the mode signal MDH), Iao = Ib, while Iag = 0. On the other hand, in the H level period of the mode signal MDH (that is, the L level period of the mode signal MDL), Iao = 0, while Iag = IBAT + If · Df.

The adder 95 outputs the sum of the output value Iao of the multiplier 94 and the output value Iag of the multiplier 98 as the armature current calculated value Iah. Therefore, during the period when the diodes 57 and 58 are turned on (that is, the H level period of the mode signal MDH), the armature current calculated value Iah can be generated according to the above equation (13). Further, in the period when the diodes 57 and 58 are turned off (H level period of the mode signal MDL), the DC current Ib in the output voltage control circuit 40 is regarded as the armature current Ia as in the first embodiment. , The armature current calculated value Iah can be generated (Iah = Ib).

With reference to FIG. 16 again, the armature current calculation value Iah by the armature current calculation unit 93 is input to the torque calculation unit 82 together with the exciting current If (detection value).

FIG. 18 shows a configuration example of the torque calculation unit 82 of FIG.

With reference to FIG. 18, the torque calculation unit 82 has a mutual inductance calculation unit 88 and multipliers 89 and 90 similar to those in FIG. In the third embodiment, the detection value of the exciting current If and the armature current calculation value Iah by the armature current calculation unit 93 are input to the mutual inductance calculation unit 88.

The mutual inductance calculation unit 88 reads the value on the horizontal axis of the characteristic diagram of FIG. 11 from the input current Ib in the first embodiment to the armature current calculation value Iah, and reciprocally between the armature and the field winding. Generate the calculated inductance value Lafh. Further, the multipliers 89 and 90 can calculate the torque calculation value Teh as Teh = Lafh · If · Iah.

Alternatively, when the mutual inductance Laf between the armature and the field winding can be set to a constant value, in the configuration of FIG. 9 (Embodiment 1), the torque calculation unit 82 is replaced with the input current Ib. By inputting the armature current calculated value Iah, it is possible to calculate the torque calculated value Teh in the equation (10) with Ia = Iah.

In the control configuration of FIG. 16, the control contents other than the torque calculation are the same as those in the first embodiment. Therefore, also in the third embodiment, the switching element 48 of the exciting current control circuit 50 is controlled in the same manner as in the first embodiment.

As described above, in the wind power generation device according to the third embodiment, the bypass path of the output voltage control circuit (boost chopper) 40 can be formed by turning on the switch 55. Therefore, since the generator 20 can be operated in a state where the wind speed is sufficiently high and the rotation speed is high, the output voltage control circuit 40 is bypassed when the power storage element 30 can be charged without boosting the output voltage of the generator 20. By reducing the power loss, the amount of charge to the power storage element 30 can be increased.

Further, due to the arrangement of the diodes 58 and 52, when the output voltage of the generator 20 is higher than the output voltage of the power storage element 30, the output voltage of the generator 20 is directly supplied to the exciting current control circuit 50 to excite the current. By generating If, the power consumption required for excitation can be reduced.

Further, also in the third embodiment, by providing the armature current calculation unit 93 (FIG. 16), the armature current can be calculated without newly providing a detector for the output current from the generator 20. .. This makes it possible to control the torque generated by the generator 20 without providing a torque detector.

Further, the exciting current control circuit 50 is controlled by using the common exciting current control unit 69 (FIG. 16) both at the time of boosting by the output voltage control circuit 40 and at the time of bypassing the output voltage control circuit 40. Can be done.

In the present embodiment, an example in which the rotation speeds of the propeller 5 and the generator 20 are the same value has been described, but the rotation speed of the propeller 5 (wind turbine) and the generator 20 ( Similar output voltage control and exciting current control can be applied to the wind turbine generator even when there is a known ratio (K) with the rotation speed of the rotor). Specifically, the rotation speed of the propeller 5 (wind turbine) is calculated by multiplying the rotation speed detection value of the generator 20 generated by the rotation speed detection value generation unit 62 (FIGS. 6 and 13) by K. Is possible. Further, the torque command value Teref (FIGS. 9 and 16) of the generator 20 can be calculated by multiplying the desired torque value of the propeller 5 (wind turbine) by (1 / K).

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

5 propeller, 10 wind generator, 20 generator, 21-25 terminals (generator), 27 armature winding, 28 field winding, 29 rectifier, 30 current storage element, 40 output voltage control circuit, 41, 42, 46 Smoothing capacitor, 43,47,51-53,56-58 diode, 44,48 switching element, 45 reactor, 50 excitation current control circuit, 54,55 switch, 60 generator control unit, 62 rotation speed detection value generator , 64,68 Output voltage control unit, 66,69 Excitation current control unit, 67 mode determination unit, 71 Output voltage command value generator, 72,83,85 subtractor, 73,77 voltage controller, 74,87 comparer , 81 Torque command value generator, 82 Torque calculation unit, 84 Torque controller, 86 Current controller, 88 Mutual inductance calculation unit, 89, 90, 94, 96, 98 Multiplier, 91 Hysteresis comparator, 93 Armature current calculation Unit, 95,97 adder, 210 maximum output line, CW carrier, Db, Df duty ratio, Iah armature current calculated value, Ib output current, Ib DC current, If excitation current, Ifref excitation current command value, Laf mutual inductance , Lafh mutual inductance calculated value, MDH, MDL mode signal, Nth threshold, Nin input node (output voltage control circuit), Nf input node (excitation current control circuit), Now output node (output voltage control circuit), Ra armature winding Line resistance, Rf electric resistance value, SGb, SGf gate signal, Tea torque calculation value, Teref torque command value, VBAT DC voltage, Vb input voltage (output voltage control circuit), Vbref output voltage command value, Vout output voltage (output voltage) Control circuit), Vp AC voltage (terminal 21).

Claims (8)

A field winding provided on the rotor mechanically connected to the rotating shaft of the propeller, an armature winding provided on the stator, and connected between the armature winding and the output terminal. A generator with a rectifier and
A power storage element charged by the DC power output by the generator to the output terminal, and
A second output node electrically connected to the power storage element with respect to a first DC voltage of the input node connected between the output terminal and the power storage element and electrically connected to the output terminal. An output voltage control circuit that controls the boost ratio of DC voltage,
An exciting current control circuit that is electrically connected to the power storage element and the field winding and controls the exciting current supplied to the field winding.
A controller for controlling the operation of the output voltage control circuit and the exciting current control circuit is provided.
The controller
A rotation speed detection unit that detects the rotation speed of the rotation shaft, and
The output voltage command value of the generator is determined according to the rotation speed detected by the rotation speed detection unit, and the output voltage control circuit of the output voltage control circuit so that the first DC voltage matches the output voltage command value. The output voltage control unit that controls the boost ratio and
The exciting current control unit determines the exciting current command value according to the rotation speed detected by the rotation speed detecting unit, and controls the operation of the exciting current control circuit so that the exciting current matches the exciting current command value. And including wind power generators. A first switch provided in the path between the output node and the power storage element of the output voltage control circuit, and
A second switch provided in the bypass path of the output voltage control circuit formed between the output terminal and the power storage element is further provided.
The controller
It further has a mode determination unit for turning the first and second switches on and off in a complementary manner.
The mode determination unit turns off the first switch and turns on the second switch in the operating state of the generator capable of charging the power storage element without boosting the first DC voltage. The wind power generator according to claim 1. The exciting current control unit determines a torque command value according to the rotation speed detected by the rotation speed detecting unit, and also detects an output current from the output terminal of the generator and a detected value of the exciting current. The wind power generator according to claim 1 or 2, wherein the exciting current command value is determined so that the torque calculation value calculated using the above-mentioned torque command value matches the torque command value. The exciting current control unit has a predetermined change characteristic of the armature current of the generator and the mutual inductance with respect to the exciting current, a detected value of the output current regarded as the armature current, and the exciting current. The wind power generator according to claim 3, wherein the torque calculation value is calculated by using the calculated value of the mutual inductance calculated from the detected value. A first diode connected between the power storage element and the input side of the exciting current control circuit with the direction from the power storage element to the exciting current control circuit as the forward direction.
1 or claim 1, further comprising a second diode connected between the output terminal and the input side of the exciting current control circuit with the direction from the output terminal to the exciting current control circuit as the forward direction. The wind power generator according to 2. The exciting current control circuit is configured to control the current ratio between the first input current to the exciting current control circuit and the exciting current supplied to the field winding.
The exciting current control unit
A product of the detected value of the second input current to the power storage element, the detected value of the exciting current, and the current ratio during the period in which the power storage element can be charged without boosting the first DC voltage. Has an armature current calculation unit that calculates an output current calculated value from the output terminal of the generator by adding and
The exciting current control unit determines a torque command value according to the rotation speed detected by the rotation speed detection unit, and the calculated output current value and the calculated torque value calculated using the exciting current are the torque. The wind power generator according to claim 5, wherein the exciting current command value is determined so as to match the command value. The exciting current control unit detects the armature current of the generator and the change characteristic of the mutual inductance with respect to the exciting current, the calculated output current value regarded as the armature current, and the exciting current. The wind power generator according to claim 6, wherein the torque calculation value is calculated by using the calculated value of the mutual inductance calculated from the value. 3. The exciting current control unit determines the torque command value according to the rotation speed detected by the rotation speed detection unit based on the characteristic relationship between the rotation speed and the torque of the propeller obtained in advance. 4. The wind power generator according to any one of 4, 6, and 7.

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