JP4060687B2 - Pumping device using solar cell and operation control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is driven by a brushless motor having a rotor with a solar cell as a power source and a permanent magnet disposed thereon and a stator having multi-phase (for example, three-phase) windings, and the pump is controlled at a variable speed by a frequency converter such as an inverter. The present invention relates to a pumping device using an operable solar cell and an operation control method thereof .
[0002]
[Prior art]
Converting the DC output power of solar cells into AC power using an inverter and supplying it to the pump device, etc. enables water supply and irrigation even in remote areas such as mountainous areas where stable power supply is not easy. Very useful. In such an area, it may be possible to pump water from a well or the like using an engine-driven pump or the like, but it is inconvenient because it requires fuel supply. That is, in such a system using an engine-driven pump or the like, there may be a situation where water supply is stopped when fuel supply is interrupted. On the other hand, when a solar cell is used as an energy source, fuel supply is not required, and water can be pumped as long as there is sunlight, which is extremely convenient.
[0003]
This type of pumping device includes a solar cell that converts sunlight into electrical energy, an inverter that converts DC power supplied from the solar cell into AC power suitable for pump operation, and supply of AC power from the inverter. The motor is configured to receive and start the motor and a pump driven by the motor. In general, a motor and pump in which a pumping motor and a pump are integrated are installed at the bottom of a deep well or the like, and pumping is performed by starting the motor. The pumped water is accumulated in a tank on the ground. Thus, in the pumping device using a solar cell, it operates by the electric power generated according to the amount of solar radiation, but since the pumped water is once accumulated in the tank, it can be used as needed. .
[0004]
As a pump used in the pumping device, a submersible pump is generally used, and a three-phase induction motor is generally used as a motor for driving the pump, and three-phase AC power is supplied by an inverter. The amount of power that can be supplied by the solar cell varies depending on the amount of solar radiation. For this reason, maximum power tracking control is performed to control the frequency supplied to the motor so that the output power of the solar cell becomes the maximum power. The following items are desired for a pumping device using such a solar cell.
[0005]
(1) In order to efficiently use solar energy, it is necessary to maximize the efficiency of the entire system.
[0006]
(2) Since the pump is disposed inside the well or the like, it is desired that the pump itself is robust and has a small size and light weight, and that there is no failure.
[0007]
(3) It must be easy to handle so that those who operate the pump can easily operate it.
[0008]
Conventionally, in order to increase the efficiency of a motor pump, it has been considered to use a highly efficient brushless motor for the motor. The brushless motor switches and controls the current supplied to the inverter winding according to the rotation angle of the rotating shaft. That is, the brushless motor rotates the rotating shaft by supplying current to the motor windings sequentially in accordance with the detected rotation angle of the rotating shaft. In general, the rotation angle of a rotating shaft is detected using a magnet fixed to a part of the rotating shaft and a position sensor such as a Hall element that detects the position of the magnet. For this reason, a position sensor for detecting the rotation angle of the rotation shaft, a sensor circuit associated therewith, a sensor wiring for transmitting the rotation angle of the rotation shaft to the inverter, and the like are required.
[0009]
However, since the motor pump is arranged at the bottom of the well as described above, the method using the position sensor such as the Hall element as described above increases the wiring, so it is not suitable for the submersible motor pump installed inside the well. Met. In addition, as the number of parts such as sensor elements and sensor amplifiers increases, the possibility of failure increases accordingly, and maintenance becomes necessary. In order to prevent such sensor wiring from being exposed to the outside, there is a method in which the sensor wiring is installed in the motor casing including the inverter. However, when the inverter is installed in the motor casing as described above, the space of the motor itself is increased, the structure of the motor pump itself is complicated, and the maintenance burden is also increased.
[0010]
In order to avoid the inconveniences as described above, in recent years, a sensorless motor that does not have a sensor for detecting the magnetic position of the rotor is used as a motor that drives a pump. Instead of using a sensor that detects the magnetic position, this sensorless motor detects the induced voltage generated during rotation of the rotor from the windings of the non-energized phase and estimates the rotor rotation angle based on that signal. Switch and control the winding that supplies the current. However, this type of sensorless brushless motor requires a non-energized phase for detecting an induced voltage, and therefore cannot be driven by a 180-degree sine wave energizing method that is generally used in general-purpose inverters. Conducting rectangular wave energization at a degree. Furthermore, since a complicated circuit for processing a signal for determining the phase to be energized is required, there is a problem that an expensive driving inverter is required for each motor.
[0011]
[Patent Document 1]
Japanese Patent Laid-Open No. 2002-21736
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described points, and uses a highly efficient brushless motor as a pump driving motor. It is an object of the present invention to provide a pumping device using a battery and an operation control method thereof.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problems, a first aspect of the present invention provides a brushless motor including a rotor having a permanent magnet and a stator having a magnetic field having saliency and a stator having multiphase windings, and a brushless motor. The pump driven by the motor and the frequency of the driving power supplied to the brushless motor according to the amount of power generated by the solar cell, and the maximum shaft power of the pump at each operating frequency of the brushless motor is the brushless motor at the operating frequency Is provided with a frequency converter that controls the voltage of the driving power based on the V / F characteristic that is within the output that causes step-out.
[0014]
As described above, by configuring the magnetic field of the permanent magnet disposed in the rotor of the brushless motor to have saliency, reluctance torque can be obtained as described in detail later, and the torque generated in the brushless motor is the magnet. The magnet torque and reluctance torque by excitation are combined (see FIG. 7), and the torque angle at the maximum value of the combined torque is 90 degrees or more. As a result, the brushless motor can be driven in the vicinity of the 90 ° torque angle with the best power factor even with a general-purpose inverter of 180 ° sine wave energization method that does not have the rotor magnetic pole position detection means. In addition, the frequency converter determines the voltage for each operating frequency that the frequency converter supplies to the brushless motor so that the required maximum output of the pump at each operating frequency is within the output that causes the brushless motor to step out. It is possible to avoid it.
[0015]
The invention described in claim 2 is the pumping device using the solar battery according to claim 1, wherein the voltage supplied to the brushless motor by the frequency converter is the voltage supplied from the solar battery to the frequency converter. Regardless of the operation frequency, the operation frequency is constant.
[0016]
In general, in a frequency converter such as an inverter, as will be described in detail later, even when the output frequency is constant, when the input voltage changes, the output voltage also changes. Therefore, when a solar cell is used as a power source, the power supply voltage constantly fluctuates, so that the V / F characteristic fluctuates following the voltage change, and the optimum V / F characteristic that can avoid step-out cannot be maintained. . Here, the voltage supplied to the brushless motor by the frequency converter is constant for each operating frequency regardless of the voltage supplied from the solar battery to the frequency converter, so that stable operation is possible even with the solar battery as the power source. Become.
[0017]
The invention according to claim 3 is the pumping device using the solar cell according to claim 1 or 2, wherein the multi-phase winding of the stator of the brushless motor is a three-phase winding, and the V / F characteristic is The maximum shaft power of the pump at the frequency is determined to be within 1.5 times the motor output at which the power factor of the brushless motor at the operating frequency is maximum.
[0018]
When a three-phase brushless motor is driven by a general general-purpose inverter, as will be described in detail later, the ratio of torque τmax at which step-out occurs to torque τ ₉₀ at which the power factor becomes maximum is τmax / τ ₉₀ = 1.5 is experimentally confirmed (see FIG. 7). Further, since the combined torque of the brushless motor is increased or decreased in accordance with the voltage applied to the windings (see FIG. 8), the operating frequency throughout as required maximum torque τpmax pump at a certain frequency is within 1.5 times the tau ₉₀ If the motor applied voltage for each operating frequency is determined, step-out can be reliably avoided.
[0019]
According to a fourth aspect of the present invention, there is provided a brushless motor including a rotor having a permanent magnet and a magnetic field having a saliency, a stator having a multiphase winding, and a pump driven by the brushless motor. An operation control method for a pumping device comprising a frequency converter for converting the output power of a solar cell and supplying drive power to the brushless motor, wherein the maximum shaft power of the pump at each operating frequency of the brushless motor A V / F characteristic is determined in advance so that the brushless motor at an operating frequency is within an output that causes a step-out, and a driving power voltage supplied from a frequency converter is determined according to the V / F characteristic. To do.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of the entire water supply apparatus according to the present invention. As shown in FIG. 1, the water supply apparatus according to the present invention includes a solar cell 1 that converts sunlight into electric energy, an inverter 2, a motor pump 3 installed at the bottom of a well 6, and a water storage tank 5. Yes. The DC power generated by the solar cell 1 is converted into AC power suitable for its operation by the inverter 2 and supplied to the motor pump 3.
[0021]
The motor pump 3 is a submersible motor pump in which a pump and a canned motor are integrated. By operating the motor pump 3, the water in the well 6 is pumped and stored in the storage tank 5 through the discharge pipe 4. . The water in the water storage tank 5 is supplied to a required area through the pipe 8 by opening the valve 7.
[0022]
The motor part of the motor pump 3 is a brushless motor that is arranged with a permanent magnet in the rotor and is rotated by a rotating magnetic field generated from the stator, and its main part configuration is shown in FIG. The brushless motor includes a stator 12 and a rotor 11 disposed at the center of the stator 12.
[0023]
The stator 12 includes windings 12u ₁ , 12u ₂ , 12v ₁ , 12v ₂ , 12w by salient pole concentrated winding on the magnetic pole portions U ₁ , U ₂ , V ₁ , V ₂ , W ₁ , W ₂ of the 6-slot stator core 14. _1, constitutes a 12w ₂ wound. Then, as shown in FIG. 3, the U-phase winding by connecting the windings 12u ₂ wound on the winding 12u ₁ and pole U ₂ wound on the magnetic pole U ₁ in series, wound on the magnetic pole V ₁ The winding 12v ₁ and the winding 12v ₂ wound around the magnetic pole V ₂ are connected in series to form a V-phase winding, and the winding 12w ₁ wound around the magnetic pole W ₁ and the winding wound around the magnetic pole W ₂ and a W-phase winding by connecting the line 12w ₂ in series. The U-phase winding, V-phase winding, and W-phase winding are connected to the star connection.
[0024]
Permanent magnets 11 a, 11 b, 11 c, and 11 d are provided on the outer periphery of the rotor 11. Here, an isotropic bonded magnet ring (a magnet in which magnetic particles are hardened with resin and formed in a ring shape) is used, and sinusoidal magnetization is applied to the four poles as shown in FIG.
[0025]
As described above, when a brushless motor is used for the motor portion of the motor pump and the magnetic fields of the permanent magnets 11a, 11b, 11c, and 11d arranged on the rotor 11 have saliency, reluctance torque is obtained. As shown in FIG. 7, the torque generated in the motor is the combined torque C of the magnet torque A and the reluctance torque B by magnet excitation, and the maximum value of the combined torque C, that is, the torque angle at the maximum combined torque τmax is 90 degrees or more. It becomes. As a result, the brushless motor can be driven at a torque angle of about 90 degrees with the best power factor even with a general-purpose inverter of 180 degree sine wave energization type that does not have the magnetic pole position detection means of the rotor 11. .
[0026]
The inverter 2 converts the DC power generated by the solar cell 1 into AC power by pulse width modulation under the control of the control device 10, and supplies the AC power to the motor pump 3 through the cable 9. At this time, the inverter 2 changes the frequency supplied to the motor pump 3 according to the amount of power generated by the solar cell 1 that gradually changes according to the amount of solar radiation, and the maximum shaft power of the pump at each frequency is the brushless motor at that frequency. The supplied voltage is controlled in accordance with a predetermined output frequency-output voltage characteristic (V / F characteristic) such that the power factor of the motor is within 1.5 times the maximum motor output.
[0027]
When the brushless motor is driven by a general general-purpose inverter, the ratio of the torque τ _{90 at} the torque angle at which the torque that causes the step-out, that is, the maximum combined torque τmax and the torque angle at which the power factor is 90 degrees is τmax / τ ₉₀ = 1. It has been confirmed by experiments that it is about .5. Further, since the combined torque C increases or decreases as shown in FIG. 8 in accordance with the voltage V1, V2 applied to the windings, as required maximum resultant torque τmax pump at a certain frequency is within 1.5 times the torque tau _90, If the applied voltage Vi for each operating frequency, that is, the voltage that the inverter 2 supplies to the brushless motor of the motor pump 3 is determined in the entire operating frequency, the step-out can be reliably avoided.
[0028]
In the case of a pump, especially a submersible motor pump in which the motor and the pump are integrated, it is difficult to actually measure the required torque of the pump, so it is easier to determine the aforementioned applied voltage based on the motor output instead of actually measuring the torque. It is. That is, since the output of the motor is the product of torque and rotational speed, if the applied voltage is determined so that the maximum shaft power of the pump is within 1.5 times the motor output at which the power factor of the brushless motor is maximum, It is possible to reliably avoid step-out as described above.
[0029]
FIG. 5 is a diagram showing V / F characteristics in the present embodiment. As shown in the figure, this V / F characteristic increases the output voltage at a constant increase rate with respect to the frequency increase in the frequency range of 0 to 100 (Hz), and increases more when the frequency exceeds 100 (Hz). The output voltage increases at a rate. FIG. 6 is a diagram showing the relationship between the frequency output and the motor power factor when the brushless motor is actually operated with the V / F characteristics. As shown in the figure, the frequency was changed to 100 Hz, 134 Hz, 167 Hz, and 200 Hz, and the power factor in the pump shaft power range at each frequency was measured. As a result, it is understood that the pump maximum shaft power at each frequency ≦ 1.5 Ppfmax (Ppfmax: motor output at which the power factor is maximized).
[0030]
In addition, since the function (V / F adjustment function) which changes the voltage supplied to a motor for every driving frequency is a function which a general purpose inverter has, and is a function equipped as standard, a brushless motor Without using a dedicated inverter, it is possible to operate a brushless motor without using a general-purpose inexpensive inexpensive inverter.
[0031]
In a frequency converter such as an inverter that performs frequency conversion by normal pulse width modulation, the V / F characteristic is controlled as follows.
duty ratio = f (F), Vout = Vin / 2 ^1/2 duty ratio where
Duty ratio: Duty ratio in pulse width modulation F: Output frequency (Hz) of inverter 2
Vout: output voltage (V _AC ) of the inverter 2 at the output frequency F
Vin: Input voltage of inverter 2 (V _DC )
[0032]
According to the above control, even when the output frequency F is constant, when the input voltage Vin changes, the output voltage Vout of the inverter 2 also changes. Therefore, when the solar cell 1 is used as a power source, the power supply voltage constantly fluctuates, so that the output voltage Vout also follows the voltage change, the V / F characteristic fluctuates, and an optimum V / F characteristic that can avoid step-out is obtained. It cannot be maintained. Therefore, here (invention according to claim 2), the voltage for each operating frequency supplied to the brushless motor is constant for each operating frequency regardless of the voltage supplied from the solar cell 1 to the inverter 2. The F characteristic is controlled as follows. duty ratio = f (F), Vout = Vb × duty ratio, Vb: specified voltage (VAC) at rated frequency
As a result, even when a solar cell whose output voltage is constantly changing is used as the power source, the optimum V / F characteristics can be maintained, so that the brushless motor can be stably operated without fear of stepping out. It becomes.
[0033]
In the above example, a brushless motor having a three-phase winding in the stator has been described as an example. However, the motor is not limited to a three-phase winding, and may have three or more phases. In short, the voltage for each operating frequency that the frequency converter supplies to the brushless motor is set so that the maximum shaft power of the pump at each operating frequency is within the output that causes the step-out of the brushless motor at that operating frequency throughout the operating frequency. You just have to decide.
[0034]
【The invention's effect】
As described above, according to the invention described in each claim, the following excellent effects can be obtained.
[0035]
According to the first aspect of the present invention, the frequency of the driving power supplied to the brushless motor according to the amount of power generated by the solar cell is configured such that the magnetic field of the permanent magnet disposed on the rotor of the brushless motor has saliency. Frequency conversion for controlling the voltage of the driving power based on the V / F characteristic in which the maximum shaft power of the pump at each operating frequency of the brushless motor is within the output at which the brushless motor at the operating frequency is out of step. since with the vessel, it is possible to stably operate the brushless motor using an inexpensive inverter having no magnetic pole position detection of the rotor to the frequency converter.
[0036]
According to the invention described in claim 2, since the voltage of the driving power supplied to the brushless motor by the frequency converter is constant for each operating frequency regardless of the voltage supplied from the solar cell to the frequency converter, Even when a solar cell whose output voltage is changing is used as a power source, the optimum V / F characteristic can be maintained, so that the brushless motor can be stably operated without fear of step-out.
[0037]
According to the third aspect of the present invention, the maximum shaft power of the pump at each operating frequency of the brushless motor of the three-phase winding is within 1.5 times the motor output at which the power factor of the brushless motor at the operating frequency is maximum. Since the frequency converter determines the voltage for each operating frequency that the frequency converter supplies to the brushless motor, it is possible to stably operate the brushless motor using an inexpensive inverter that does not detect the magnetic pole position of the rotor in the frequency converter. it can.
[0038]
According to the invention described in claim 4, as in the invention described in claim 1, the brushless motor can be stably operated by using an inexpensive inverter having no rotor magnetic pole position detection in the frequency converter.
[0039]
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an entire water supply apparatus according to the present invention.
FIG. 2 is a diagram showing a main part configuration of a brushless motor for driving a pump of a water supply apparatus according to the present invention.
FIG. 3 is a view showing a connection state of windings of a brushless motor for driving a pump of a water supply apparatus according to the present invention.
FIG. 4 is a diagram illustrating a rotor magnetization state of a brushless motor for driving a pump of a water supply apparatus according to the present invention.
FIG. 5 is a diagram showing a V / F characteristic of a brushless motor for driving a pump of a water supply apparatus according to the present invention.
FIG. 6 is a diagram illustrating a relationship between an output for each frequency and a power factor of a brushless motor for driving a pump of a water supply apparatus according to the present invention.
FIG. 7 is a diagram showing a characteristic state of a brushless motor for driving a pump of a water supply apparatus according to the present invention.
FIG. 8 is a diagram illustrating a characteristic state when the applied voltage of the brushless motor for driving the pump of the water supply device according to the present invention is changed.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Solar cell 2 Inverter 3 Motor pump 4 Discharge pipe 5 Water storage tank 6 Well 7 Valve 8 Piping 9 Cable 10 Control apparatus 11 Rotor 12 Stator 14 Stator core

Claims (4)

A brushless motor comprising a rotor having a permanent magnet and a stator configured so that the magnetic field has saliency and a multiphase winding;
A pump driven by the brushless motor ;
With changing the frequency of the supplied drive power to the brushless motor in accordance with the power generation amount of solar cells, the brushless motor maximum shaft power of the pump at each operating frequency of the brushless motor is in said operation frequency is the step-out A pumping device using a solar cell, comprising a frequency converter that controls the voltage of the driving power based on a V / F characteristic that is within the generated output. In the pumping apparatus using the solar cell according to claim 1,
A solar cell characterized in that the voltage of the driving power supplied to the brushless motor by the frequency converter is constant for each operating frequency regardless of the voltage supplied from the solar cell to the frequency converter. Pumping equipment. In the pumping device using the solar cell according to claim 1 or 2,
The multiphase winding of the stator of the brushless motor is a three-phase winding, and the V / F characteristic indicates that the maximum shaft power of the pump at each operating frequency is the maximum power factor of the brushless motor at the operating frequency. A pumping device using a solar cell, characterized in that it is determined to be within 1.5 times the motor output. The permanent magnets are arranged, power brushless motor the magnetic field is equipped with a stator having a configured rotor and polyphase winding to have saliency, a pump driven by the brushless motor, the output power of the solar cells An operation control method for a pumping device comprising a frequency converter for converting and supplying driving power to the brushless motor,
The V / F characteristic is determined in advance so that the maximum shaft power of the pump at each operation frequency of the brushless motor is within the output at which the brushless motor at the operation frequency generates step-out, and is supplied from the frequency converter. An operation control method for a pumping device, wherein the voltage of the driving power is determined according to the V / F characteristic.

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