JP4595372B2 - Compressor, compressor drive control device, and compressor drive control method - Google Patents

Description

  The present invention relates to a compressor used in an air conditioner or the like, a compressor drive control device, and a compressor drive control method.

  A general air conditioner performs heat transfer by circulating a refrigerant through a heat exchanger in a compressor. In many cases, a hermetic compressor is used as the compressor. FIG. 3 shows a cross-sectional view of a conventional scroll-type hermetic compressor used in a small domestic air conditioner. The compressor container 1 is made of metal and has a scroll-type compression inside. A mechanism 2 and a motor 3 for driving the compression mechanism 2 are arranged, and a voltage application terminal (terminal) 4 for supplying electric power to the motor 3 is provided on the compressor head. 5 is a suction pipe, and 6 is a discharge pipe.

  The compression method includes a rotary method in addition to the scroll method, but the configuration in which the compression mechanism 2 and the motor 3 are arranged is the same. The general configuration of the current home air conditioner is to perform capacity control by changing the speed of the compressor with an inverter.

In recent years, air conditioners are required to have high operating efficiency from the viewpoint of protecting the global environment. To that end, it is necessary to optimally design the cylinder volume of the compressor. For example, in the case of a separate type small air conditioner for home use, in the case of the super energy saving type, the cylinder volume of the compressor is about 11 cc in the 2.2 to 4.0 kW class, and in the 5.6 to 6.3 kW class. About 13cc. The cylinder volume is determined so that the compression efficiency of the compressor is maximized in accordance with the refrigeration cycle at the rated capacity with long operating hours throughout the year (for both cooling and heating refrigeration cycles). Designed with the most favorable compromise).

  On the other hand, the motor 3 that drives the compression mechanism 2 is also highly efficient. As the motor 3, an IPM (embedded magnet motor) is used as a high-efficiency DC brushless motor using a rare earth magnet, and the speed of the motor 3 is varied by an inverter power source to adjust the air conditioning capacity.

  FIG. 4 is a configuration diagram of a DC brushless motor (IPM). In the motor 3, copper windings 12 are wound around the stator 11 for each of the U, V, and W phases, and a field is created by causing current to flow therethrough. The rotor 13 is composed of an iron core 14 and a permanent magnet 15 embedded therein, and a magnet torque and a reluctance torque are generated by the field to receive a rotational force. The winding 12 is connected to a voltage application terminal 16 (= voltage application terminal 4 in FIG. 3) provided at the head of the compressor, and a voltage from the inverter power source is applied between the terminals to supply a current to the winding 12. Shed. FIG. 5 is a U-phase winding diagram, and only the U-phase winding portion in FIG. 4 is described. Arrows indicate the flow of current when a voltage is applied between the UV phases.

  In the case of a DC motor, if the diameter of the stator winding 12 is the same, increasing the number of turns will improve the efficiency. Therefore, if the number of turns of the stator winding 12 is increased as much as possible, the rated capacity It is preferable to make the specification that maximizes the motor efficiency.

  However, since the cylinder volume of the compressor is determined by the compression efficiency as described above, when a large capacity is required for the air conditioner, that is, when the difference between the set temperature and room temperature is large (particularly at startup). The air conditioning capacity must be increased by increasing the compressor speed. In general, the maximum speed required for heating is higher than the maximum speed required for cooling, and depending on the model, the compressor speed is nearly twice the compressor speed at the rated capacity of heating. Is needed. Therefore, it is necessary to design the motor of the compressor so that the maximum heating speed can be secured. In DC motors, if the winding wire diameter is the same, increasing the number of stator turns will improve efficiency, but since the high-speed torque is reduced and the maximum speed is reduced, the maximum number of turns can be secured for heating. Must be designed with the number of turns.

  This means that the motor design must be at the expense of efficiency at rated capacity to ensure maximum speed.

  As one countermeasure against this problem (that is, a measure for securing a high-speed torque while increasing the number of windings of the stator winding as much as possible), field-weakening control is often used in DC motor inverter control. The field weakening control is a control in which the positional relationship between the stator winding and the rotor is advanced and energized in phase. This can increase the torque in the high speed range, but the improvement rate of the maximum speed is still about 10 to 20 Hz.

  Taking an air conditioner of the 2.8 kW class as an example, the speed at the rated capacity is about 60 Hz, and considering only the efficiency at this operating point, it is efficient to wind up the winding to about 250 turns. Is the highest. However, even if the maximum speed is weakened and field control is used with this number of turns, the torque limit is reached at about 80 to 90 Hz, and the required 120 Hz cannot be driven. At the expense of motor efficiency at the rated capacity, the number of turns was about 150 turns that could be driven at a maximum speed of 120 Hz (FIG. 5). As described above, in the conventional compressor, there is a problem that the number of turns that maximizes the motor efficiency at the rated capacity cannot be achieved because the maximum speed is ensured.

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object of the present invention is to provide a compressor that achieves both maximum speed and high efficiency at rated capacity.

In order to solve the above-described conventional problems, a compressor according to the present invention is a compressor driven by a DC brushless motor including a stator and a rotor, and a stator winding wound around the stator, and a power source for the stator winding. A voltage application terminal for supplying the voltage, and connecting the voltage application terminal with a different number of turns of the stator winding of each phase, and applying the voltage according to the driving condition of the compressor By switching the terminal and changing the number of turns of the stator winding to be energized, when operating the compressor so as to ensure high-speed torque, the location where the number of turns of the stator winding is small Switch to apply the voltage to the voltage application terminal connected to, and when operating at the rated capacity, apply the voltage to the voltage application terminal connected to the place with many windings For example, when operating the compressor at the highest speed, if the voltage is applied to the voltage application terminal connected to the part where the number of turns of the stator winding is small, the highest speed drive is achieved. When driving at rated capacity, if the voltage is applied to the voltage application terminal connected to a place with a large number of windings, the motor is driven at a high motor efficiency point. be able to.

The compressor drive control device according to the present invention is a compressor drive control device that controls a DC brushless motor that includes a stator and a rotor and drives the compressor. The stator winding wound around the stator, and the stator winding A voltage application terminal for supplying power to the power source, connecting the voltage application terminal with a different number of turns of the stator winding of each phase, and applying the voltage according to the driving condition of the compressor By switching the voltage application terminal, the number of turns of the stator winding to be energized is changed. For example, when the compressor is operated at the highest speed, it is connected to a place where the number of turns of the stator winding is small. If voltage is applied to the voltage application terminal, the motor torque necessary for maximum speed driving is secured sufficiently, and when operating at the rated capacity, there are many winding points. If to apply a voltage to the voltage application terminal connected, it is possible to perform driving at a high motor efficiency point.

Furthermore, the compressor drive control method of the present invention is a compressor drive control method for controlling a DC brushless motor that comprises a stator and a rotor and drives the compressor. The stator winding wound around the stator, and the stator A voltage application terminal for supplying power to the winding, and connecting the voltage application terminal with a different number of turns of the stator winding of each phase, and applying a voltage according to the driving condition of the compressor The voltage application terminal is switched to control the number of turns of the stator winding to be energized. For example, when the compressor is operated at the highest speed, the number of turns of the stator winding is small. If voltage is applied to the voltage application terminal connected to, the motor torque necessary for maximum speed drive is sufficiently secured, and when operating at rated capacity, the number of turns If to apply a voltage to the voltage application terminal connected to the high position, it can be performed driving at high motor efficiency point.

  According to the compressor, compressor drive control device, and compressor drive control method of the present invention, it is possible to achieve both the highest speed of the compressor and the high efficiency at the rated capacity.

A first invention is a compressor driven by a DC brushless motor comprising a stator and a rotor, comprising a stator winding wound around the stator, and a voltage application terminal for supplying power to the stator winding, The stator windings to be energized are connected by connecting the voltage application terminals with portions of different numbers of windings of the stator windings of the phase, and switching the voltage application terminals to apply voltage according to the driving conditions of the compressor. When the compressor is operated so as to ensure a high speed torque, a voltage is applied to the voltage application terminal connected to a portion where the number of turns of the stator winding is small. When switching to, and operating at the rated capacity, it is configured to switch so as to apply a voltage to the voltage application terminal connected to a place with a large number of turns, For example, when operating the compressor at the highest speed, if the voltage is applied to the voltage application terminal connected to the part where the number of turns of the stator winding is small, the motor torque necessary for the highest speed drive is sufficiently secured. In addition, when operating at the rated capacity, driving at a high motor efficiency point can be performed by applying a voltage to a voltage application terminal connected to a place with a large number of windings.

  In particular, the second aspect of the invention is the stator winding of each phase of the first aspect of the present invention, in which the wire diameter is changed from the middle. If the thickness is increased, loss due to the resistance of the winding is reduced, and higher efficiency can be obtained with a higher rated capacity.

According to a third aspect of the present invention, there is provided a compressor drive control device for controlling a DC brushless motor including a stator and a rotor for driving a compressor, and a stator winding wound around the stator and a voltage for supplying power to the stator winding The voltage application terminal is connected, and the voltage application terminal is connected to the voltage application terminal according to the driving conditions of the compressor. In addition, the number of turns of the stator winding to be energized is changed, and when the compressor is operated so as to ensure a high speed torque, the stator winding is connected to a place where the number of turns of the stator winding is small. When switching to applying voltage to the voltage application terminal and operating at the rated capacity, switch to apply voltage to the voltage application terminal connected to the place with many windings. For example, when the compressor is operated at the highest speed, it is necessary for the highest speed drive if the voltage is applied to the voltage application terminal connected to the part where the number of turns of the stator winding is small. When driving at rated capacity, it is possible to drive at a high motor efficiency point by applying a voltage to the voltage application terminal connected to a place with a large number of windings. it can.

  In the fourth aspect of the invention, in particular, in the stator winding of each phase of the third aspect of the invention, the wire diameter is changed from the middle. If the thickness is increased, the loss due to the resistance of the winding is reduced, and higher efficiency at the rated capacity can be obtained.

According to a fifth aspect of the present invention, there is provided a compressor drive control method for controlling a DC brushless motor including a stator and a rotor and driving a compressor, and a stator winding wound around the stator, and power is supplied to the stator winding. A voltage application terminal, and connects the voltage application terminal with a portion having a different number of turns of the stator winding of each phase, and switches the voltage application terminal to apply the voltage according to the driving condition of the compressor In order to control the number of turns of the stator winding to be energized, when operating the compressor so as to ensure a high speed torque, it is connected to a place where the number of turns of the stator winding is small. When switching to apply voltage to the voltage application terminal and operating at rated capacity, apply voltage to the voltage application terminal connected to a place with a large number of turns. For example, when operating the compressor at the highest speed, if the voltage is applied to the voltage application terminal connected to the part where the number of turns of the stator winding is small, the motor required for the highest speed drive When the torque is sufficiently secured and the motor is operated at the rated capacity, driving at a high motor efficiency point can be performed by applying a voltage to a voltage application terminal connected to a portion having a large number of windings.

  In the sixth aspect of the invention, in particular, in the stator winding of each phase of the fifth aspect of the invention, the wire diameter is changed from the middle. If the thickness is increased, the loss due to the resistance of the winding is reduced, and higher efficiency at the rated capacity can be obtained.

  In the seventh aspect of the invention, in particular, when the compressor of the fifth or sixth aspect is operated at a high speed, a voltage is applied to the voltage application terminal connected to the winding having the smallest number of stator windings of each phase. Therefore, it is possible to perform the most efficient operation according to the time of various driving conditions while securing the maximum speed.

  In the eighth aspect of the invention, in particular, when the compressor according to any one of the fifth to seventh aspects is started, a voltage is applied to the voltage application terminal connected to the winding having the largest number of windings of the stator windings of each phase. Then, after predetermined driving, the voltage is switched to a voltage application terminal in accordance with the purpose, and the starting torque can be maximized to perform stable and reliable compressor starting.

In the ninth aspect of the invention, in particular, when the voltage application terminal of any one of the fifth to eighth aspects is switched, the drive of the compressor is temporarily stopped, the switching is restarted, and the voltage is applied. The characteristics of the DC brushless motor are suddenly changed by switching the winding to be performed (due to motor step-out, etc.), and the compressor can be prevented from abnormally stopping.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a U-phase winding diagram of a DC brushless motor that drives a compressor according to a first embodiment of the present invention. In addition, about the same part as a prior art example, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  In FIG. 1, the stator 11 and the rotor 13 are the same as those of the conventional example (FIG. 5). In the conventional example, the stator winding 12 wound around the stator 11 is for a 2.8 kW class copper wire having a wire diameter of φ0.85 and is wound for 150 turns. In the present embodiment, the stator winding 12 has a wire diameter of φ0.70. The winding 17 is divided into a winding 17 wound for 100 turns and a winding 18 wound for 150 turns with a wire diameter of φ0.90. Both windings are overlapped in the same stator slot or wound in series.

The voltage application terminal 16 for each phase is provided with two terminals: a voltage application terminal B16b connected to the end of the winding, and a voltage application terminal A16a to which the coupling point of the winding 17 and the winding 18 is connected. The arrows in the figure indicate the current flow when a voltage is applied between the UV phases. Although only the U phase is shown in FIG. 1, the other V and W phases have the same configuration and form a DC brushless motor 3.

  When the compressor is operated at a rated capacity and with high efficiency, a voltage is applied to the voltage application terminal B16b. At this time, as indicated by the black arrow in the figure, the current flows through the winding 18 wound by 150 turns, and then flows through the winding 17 wound by 100 turns, passing through the neutral point to the V-phase winding. Flowing.

Since the winding 17 and the winding 18 are wound in the same stator slot, the magnetic flux generated in both windings is superimposed, and the DC brushless motor 3 has a characteristic equivalent to 250 turns by adding both windings. Therefore, it is possible to obtain a compressor having the highest operating efficiency at the rated capacity. Of course, as described above, the voltage application terminal B16b can be used for driving at the maximum speed, and the torque at the high speed is insufficient and cannot be driven even if the voltage application terminal B16b is used.

Therefore, when it is desired to secure a high-speed torque even if the motor efficiency is reduced, a voltage is applied to the voltage application terminal A16a. Then, since the end of the winding is insulated in an open state, no current flows through the winding 18 as indicated by the white arrow in the figure, and a current flows only through the winding 17. In this case, since the winding 17 is wound only 100 turns, it is 10 for a DC brushless motor.
Since the characteristic can be equivalent to 0 turns, that is, a high speed torque can be secured, the compressor can be operated at the required maximum speed.

In the conventional example (FIG. 5), the wire diameter of the winding is φ0.85, but in this embodiment, φ0.90 and φ0.70 are combined. Considering the efficiency of the DC brushless motor 3, the larger the wire diameter of the motor winding is, the less copper loss is reduced and the efficiency is improved. However, in order to wind many windings with a thick wire diameter, the winding occupies that much. Since the volume increases, the stator 11 must be enlarged, leading to an increase in size and cost of the compressor.

Therefore, in this embodiment, the wire diameter of the winding 18 necessary for obtaining high efficiency during operation at the rated capacity is increased from φ0.85 to φ0.90, and even torque is obtained even if efficiency is reduced. The winding 17 used at the time of high-speed operation that can be used is φ0.70, which is the minimum wire diameter. By doing so, it is possible to selectively use motor characteristics more suitable for the purpose while suppressing an increase in the size of the DC brushless motor 3.

Furthermore, in this embodiment, two motor characteristics are obtained by dividing the winding into two, but it is also possible to obtain three or more motor characteristics by dividing the winding into three or more. Needless to say, it may be used in detail according to the operating conditions of the compressor. In that case, when starting up the compressor, it is preferable to use a voltage application terminal with the largest number of windings as the DC brushless motor 3 because high torque is required at a low speed. It is preferable to switch to a voltage application terminal according to the purpose after driving.

On the other hand, even when dividing into three or more, since it is necessary to increase the torque at high speed when driving at the highest speed, if the voltage application terminal 16 that uses the smallest number of windings as the DC brushless motor 3 is used, good.

FIG. 2 is a wiring diagram of a drive control device that drives and controls the compressor in the present embodiment. The DC brushless motor 19 of the compressor is provided with a voltage application terminal A16a and a voltage application terminal B16b for each phase at the voltage application terminal 16 arranged at the head of the compressor. Connected to. Although the electrical relay is used for the change-over switch of the voltage application terminal change-over device 20, of course, a semiconductor switch may be used.

By the way, when the voltage application terminal A16a and the voltage application terminal B16b are switched, the motor characteristics change instantaneously, and the motor current and the motor induced voltage change. The DC brushless motor that drives the hermetic compressor cannot use a position sensor for detecting the magnetic pole position. Therefore, the sensorless drive for estimating the magnetic pole position by the motor current detecting means and the motor induced voltage is performed. It is.

  Therefore, when switching the voltage application terminals A, B16a, 16b, it is necessary to simultaneously switch the control coefficient of the magnetic pole position estimation. However, when switching with the motor driving continued, sensorless driving becomes unstable at the moment of switching. In the worst case, it is possible to step out and stop abnormally. In order to prevent this, when switching the voltage application terminals A, B16a and 16b, the risk of abnormal stop can be eliminated by temporarily stopping the compressor and restarting it after switching.

  The compressor of the present invention can achieve both maximum speed and high efficiency at the rated capacity, and can operate the compressor with the optimum motor characteristics according to the operating conditions. It can be widely used for improving the efficiency and energy saving of air conditioners for vehicles and air conditioners for vehicles.

Winding diagram of DC brushless motor mounted on compressor in embodiment 1 of the present invention (only U phase is shown) Wiring diagram of the compressor drive control device that drives and controls the compressor Sectional view of a conventional scroll type hermetic compressor Configuration diagram of DC brushless motor mounted on the compressor U-phase winding diagram of the DC brushless motor

3 DC brushless motor 11 Stator 12 Stator winding 13 Rotor 16 Voltage application terminal 16a Voltage application terminal A
16b Voltage application terminal B
17, 18 Winding 19 DC brushless motor of compressor 20 Voltage application terminal switching device 21 Inverter power supply

Claims (9)

In the compressor driven by a DC brushless motor including a stator and a rotor, the compressor includes a stator winding wound around the stator and a voltage application terminal for supplying power to the stator winding, and the stator winding of each phase Are connected to the voltage application terminal, and the voltage application terminal to which the voltage is applied is switched according to the driving condition of the compressor, thereby changing the number of turns of the stator winding to be energized. When the compressor is operated so as to ensure high-speed torque, it is switched to apply a voltage to the voltage application terminal connected to a portion where the number of turns of the stator winding is small. When operating with the capacity, the compressor is configured to switch so that a voltage is applied to the voltage application terminal connected to a place with a large number of windings. The compressor according to claim 1, wherein the diameter of the stator winding of each phase is changed from the middle. In a compressor drive control device that controls a DC brushless motor that includes a stator and a rotor and drives a compressor, the stator winding wound around the stator, and a voltage application terminal that supplies power to the stator winding, The stator that is energized by connecting the voltage application terminal with a portion having a different number of turns of the stator winding of each phase, and switching the voltage application terminal to apply a voltage according to the driving condition of the compressor When the compressor is operated so as to ensure a high speed torque, a voltage is applied to the voltage application terminal connected to a portion where the number of turns of the stator winding is small. Switching to apply, when operating at the rated capacity, switching to apply a voltage to the voltage application terminal connected to the place with a large number of windings Compressor drive control device, characterized in that the. 4. The compressor drive control device according to claim 3, wherein the diameter of the stator winding of each phase is changed in the middle. In a compressor drive control method for controlling a DC brushless motor comprising a stator and a rotor and driving a compressor, the stator winding wound around the stator, and a voltage application terminal for supplying power to the stator winding, The stator that is energized by connecting the voltage application terminal with a portion having a different number of turns of the stator winding of each phase, and switching the voltage application terminal to apply a voltage according to the driving condition of the compressor When the compressor is operated so as to ensure a high speed torque, a voltage is applied to the voltage application terminal connected to a portion where the number of turns of the stator winding is small. When operating at the rated capacity, switch to apply voltage to the voltage application terminal connected to the place with many windings. Drive control method of a compressor according to claim. 6. The compressor drive control method according to claim 5, wherein the diameter of the stator winding of each phase is changed in the middle. 7. When the compressor is operated at the highest speed, switching is performed so that a voltage is applied to a voltage application terminal connected to a winding with the smallest number of stator windings of each phase. The compressor drive control method as described. When starting up the compressor, it starts by applying voltage to the voltage application terminal connected to the winding with the largest number of stator windings of each phase, and after a predetermined drive, switches to the voltage application terminal according to the purpose The drive control method for a compressor according to any one of claims 5 to 7. The compressor drive control method according to any one of claims 5 to 8, wherein when the voltage application terminal is switched, the drive of the compressor is temporarily stopped and then restarted after the switch.

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