JP4686242B2 - Control method and control apparatus for electric compressor - Google Patents

Description

  The present invention relates to a control method and a control device for an electric compressor, and particularly to a compressor used for refrigerant compression in a vehicle air conditioner, and is suitable for controlling an electric compressor driven by being supplied with power from a battery. The present invention relates to a control method and a control device.

  Electric compressor driven by a motor, especially an electric compressor used in a vehicle air conditioner (in addition to an electric compressor driven only by a dedicated motor, a hybrid compression having a drive mechanism by a dedicated motor and a drive mechanism by another drive source In order to protect the motor appropriately, it is necessary to prevent the temperature of the motor winding from becoming too high. If the temperature of the motor winding rises above the allowable temperature, the winding will cause insulation failure, which may cause a ground fault or overcurrent, which may result in electric shock or damage to other equipment.

Conventionally, when temperature protection of a motor winding is performed, a temperature sensor is attached to or near the motor winding to directly measure the temperature to protect the motor. For example, Patent Documents 1 and 2 disclose a structure in which a temperature sensor that directly detects the coil temperature of the stator is incorporated.
JP-A-7-180687 Japanese Patent Application Laid-Open No. 8-21958

  However, when the temperature sensor is attached inside the compressor as described above, there arises a problem that the structure becomes complicated and the cost is greatly increased. It is therefore desirable to protect the temperature of the motor winding without attaching a temperature sensor.

  Therefore, an object of the present invention is to obtain the temperature of the motor winding of the electric compressor in a software manner without attaching a temperature sensor based on various information, and to achieve a simple and inexpensive structure as a whole. A control method and a control apparatus are provided.

In order to solve the above-described problems, the electric compressor control method according to the present invention includes an electric compressor discharge pressure Pd , a motor rotational speed NEc , a motor drive device input current Iin, a temperature correction value Ta, and a previously determined proportionality. From the constant a ,
Tc = [(a × Pd × Iin) / NEc] + Ta
Is used to calculate the motor winding temperature Tc by calculation.

  In the present invention, the electric compressor is not only an electric compressor driven only by a built-in dedicated motor, but also a driving mechanism by a dedicated motor and a driving mechanism by another driving source (for example, an engine for vehicle travel). It is a concept including a hybrid compressor having The “motor drive device” refers to an inverter or the like having a switching element group that converts a current of a DC power source such as a battery into a current for driving a three-phase motor, as will be described later. "" Refers to the input current to the motor drive.

  In the electric compressor control method according to the present invention, it is preferable to add a temperature correction value (temperature correction coefficient) that increases or decreases depending on the operating state of the electric compressor to the motor winding temperature obtained by the above calculation. The temperature correction value (temperature correction coefficient) is set, for example, so as to increase with time when the motor rotates and to decrease with time when the motor stops.

  Further, the motor winding temperature can be obtained by adding a filter process to the calculation result. A signal easy to handle for actual control can be obtained by filtering.

  In the method for controlling the electric compressor according to the present invention, when the calculated motor winding temperature exceeds a predetermined value, it is determined that the motor is overheated and the operation of the electric compressor is stopped. it can. In this way, the motor winding is no longer overheated, and the motor winding and thus the motor is properly protected.

  In addition, after the operation of the electric compressor is stopped, the operation of the electric compressor can be controlled to resume when the calculated motor winding temperature becomes a predetermined value or less. In this way, the motor is not stopped unnecessarily for a long time, and the electric compressor can be restarted at an early stage so as to exhibit its original function.

The control device for the electric compressor according to the present invention is expressed by the following equation from the discharge pressure Pd of the electric compressor, the motor rotational speed NEc , the motor drive device input current Iin, the temperature correction value Ta, and the proportional constant a determined in advance.
Tc = [(a × Pd × Iin) / NEc] + Ta
It has the calculating means which calculates motor winding temperature Tc using .

  In this electric compressor control device, the calculation means may comprise means for adding a temperature correction value (temperature correction coefficient) that increases or decreases depending on the operating state of the electric compressor to the motor winding temperature obtained by the calculation. preferable. The temperature correction value (temperature correction coefficient) is as described above.

  Moreover, it is preferable that the said calculating means consists of a means which adds a filter process to a calculation result and calculates | requires motor winding temperature.

  Moreover, it is preferable to provide a control means for determining that the motor is overheated and stopping the operation of the electric compressor when the motor winding temperature calculated by the calculation means exceeds a predetermined value.

  Further, the control means preferably restarts the operation of the electric compressor after the operation of the electric compressor is stopped and the calculated motor winding temperature becomes a predetermined value or less.

  According to the control method and control device for the electric compressor according to the present invention, it is not necessary to provide a temperature sensor, and the motor winding temperature is calculated from the discharge pressure of the electric compressor, the motor rotation speed, and the motor drive device input current. Desired. Since it is not necessary to incorporate a temperature sensor, the structure of the compressor is simplified and the cost of the entire apparatus can be reduced.

  By the above calculation, a sufficiently practical motor winding temperature can be obtained. In particular, by applying appropriate corrections and processing to the calculation result, motor protection control can be performed more reliably.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
First, an example of an electric compressor to which the control method and the control device according to the present invention are applied will be described. FIG. 1 shows a hybrid compressor to be applied, and FIG. 2 shows an example of an electric compressor of a system that includes a dedicated motor and is driven only by the dedicated motor.

  In FIG. 1, the hybrid compressor A includes a first compression mechanism 1 and a second compression mechanism 2. The first compression mechanism 1 includes a fixed scroll 10 having an end plate 10a and a spiral body 10b, and a movable scroll that has an end plate 11a and a spiral body 11b and meshes with the fixed scroll 10 to form a plurality of working spaces 12. 11, a drive shaft 13 that engages with the movable scroll 11 to make the movable scroll 11 pivot, a clutch armature 14a fixed to the drive shaft, a pulley 14b connected to an engine such as a vehicle via a belt, An electromagnetic clutch 14 having an electromagnet 14c for detaching and attaching a clutch armature 14a and a pulley 14b, a ball coupling 15 for preventing the movable scroll 11 from rotating, and a suction port 16 formed in the casing are provided. A discharge hole 10a 'is formed in the end plate 10a of the fixed scroll. Here, the engine such as a vehicle is a concept including an internal combustion engine and a traveling electric motor.

  The second compression mechanism 2 includes a fixed scroll 20 having an end plate 20a and a spiral body 20b, and a movable scroll having an end plate 21a and a spiral body 21b and meshing with the fixed scroll 20 to form a plurality of working spaces 22. 21, a drive shaft 23 that engages with the movable scroll 21 to turn the movable scroll, a ball coupling 24 that prevents the movable scroll 21 from rotating, and a suction port 25 formed in the casing. A discharge hole 20a 'is formed in the end plate 20a of the fixed scroll.

  The hybrid compressor A includes an electric motor 26 that drives the drive shaft 23 of the second compression mechanism 2. The electric motor 26 includes a rotor 26 a and a stator 26 b that are fixed to the drive shaft 23.

  The fixed scroll 10 of the first compression mechanism 1 and the fixed scroll 20 of the second compression mechanism 2 are disposed back to back and are integrally formed. A discharge passage 30 is formed in the integrated end plates 10a and 20a. A discharge port 31 is formed at the downstream end of the discharge passage 30. A discharge hole 10 a ′ formed in the end plate 10 a of the first compression mechanism 1 and a discharge hole 20 a ′ formed in the end plate 20 a of the second compression mechanism 2 are connected to the discharge passage 30 via the check valve 32. Connected to the upstream end.

  In this way, when the hybrid compressor A in which the first compression mechanism 1 and the second compression mechanism 2 are integrally assembled is driven by the engine, the electromagnetic clutch 14 is turned on, and the engine such as a vehicle rotates. This is transmitted to the drive shaft 13 of the first compression mechanism 1 via the clutch armature 14a, and the movable scroll 11 is driven to turn by the drive shaft 13. The refrigerant gas flowing in from the suction port 16 is taken in the working space 12, the working space 12 moves toward the center of the fixed scroll 10 while reducing the volume, and the refrigerant gas in the working space 12 is compressed. The compressed refrigerant gas is discharged to the discharge passage 30 through the discharge hole 10a ′ formed in the end plate 10a of the fixed scroll 10 and the check valve 32, and to the high pressure side of the external refrigerant circuit through the discharge port 31. leak. Electric power is not supplied to the electric motor 26 that drives the second compression mechanism 2, and the electric motor 26 does not rotate. Accordingly, the second compression mechanism 2 does not operate. Since the discharge hole 20 a ′ of the second compression mechanism 2 is closed by the check valve 32, the refrigerant gas discharged from the first compression mechanism 1 does not flow back to the second compression mechanism 2.

  When the hybrid compressor A is driven by a motor, the electric motor 26 is turned on to rotate, and the rotation of the electric motor 26 is transmitted to the drive shaft 23 of the second compression mechanism 2, and the movable scroll 21 is moved by the drive shaft 23. It is swiveled. The refrigerant gas flowing in from the suction port 25 is taken in the working space 22, the working space 22 moves toward the center of the fixed scroll 20 while reducing the volume, and the refrigerant gas in the working space 22 is compressed. The compressed refrigerant gas is discharged to the discharge passage 30 through the discharge hole 20a ′ formed in the end plate 20a of the fixed scroll 20 and the check valve 32, and to the high pressure side of the external refrigerant circuit through the discharge port 31. leak. Electric power is not supplied to the electromagnetic clutch 14 of the first compression mechanism 1, and the rotation of an engine such as a vehicle is not transmitted to the first compression mechanism 1. Accordingly, the first compression mechanism 1 does not operate. Since the discharge hole 10 a ′ of the first compression mechanism 1 is closed by the check valve 32, the refrigerant gas discharged from the second compression mechanism 2 does not flow back to the first compression mechanism 1.

  In the hybrid compressor A, both the first compression mechanism 1 and the second compression mechanism 2 may be driven.

  FIG. 2 shows an example of an electric compressor of a system in which a dedicated motor is incorporated and driven by only the dedicated motor, to which the present invention is applied. In FIG. 2, the electric compressor B has only a compression mechanism 44 including a movable scroll 42 that is rotationally driven by a built-in electric motor 41 and a fixed scroll 43 that meshes with the movable scroll 42.

  The motors 26 and 41 in the hybrid compressor A or the electric compressor B as described above are controlled by a motor driving device 51 as shown in FIG. 3, for example. In this motor drive device 51, a current supplied from a DC power source 52 such as a battery mounted on a vehicle via a capacitor 53 is converted into a pair of series-connected semiconductor switching elements 54 (U and X, V and Y, W And Z) are taken out as currents for the U-phase, V-phase and W-phase of the three-phase motor and supplied to the motors 26 and 41. This motor supply current is controlled by an inverter control circuit 57 based on a command from the main control circuit 56. An input current to the motor driving device 51 can be detected by a current sensor 58.

  The hybrid compressor A or the electric compressor B as described above is incorporated, for example, in a refrigeration circuit (refrigerant circuit) of a vehicle air conditioner as shown in FIG. In FIG. 4, the refrigerant discharged from the compressor A or B is condensed by the condenser 61, the discharge pressure of the electric compressor is detected by the discharge pressure sensor 62, and expanded by the expansion valve 63, and then the evaporator. 64, is supplied to the air conditioner, and sucked into the compressor A or B again.

  In the system including the hybrid compressor A or the electric compressor B as described above, the winding temperature of the motors 26 and 41 is calculated as follows, and based on the calculation result, the electric compressor A or B is It is controlled as follows.

FIG. 5 is a flowchart illustrating an example of control. When the motor winding temperature calculation process starts, data on compressor discharge pressure (Pd), electric compressor rotation speed (motor rotation speed / NEc), and motor drive device input current (Iin) are acquired. The winding temperature (Tc) is calculated. Further, it is determined whether or not the motor is stopped, and a temperature correction coefficient (Ta) as shown below is incremented or decremented depending on whether the motor is stopped or not, respectively, and the correction coefficient (Ta) Add This temperature correction coefficient (Ta) is set so as to increase with time when the motor rotates and to decrease when the motor stops. The motor winding temperature (Tc) is calculated by the following equation.
Tc = [(a × Pd × Iin) / NEc] + Ta
Here, a is a proportionality constant obtained in advance by experiments or the like.

  The temperature correction coefficient (Ta) is increased / decreased as shown in FIG. 6, for example, according to conditions at the time of motor rotation and motor stop. That is, even if the compressor discharge pressure (Pd), the electric compressor rotation speed (motor rotation speed / NEc), and the motor drive device input current (Iin) are constant, the estimated motor winding temperature ( (Calculated temperature) is increased, and when the motor is stopped, the estimated temperature is decreased by this temperature correction term so as to be closer to the actual temperature.

  Further, in the control flow shown in FIG. 5, a filtering process is added to the calculation result as described above. By this filtering process, for example, as shown in FIG. 7, the value obtained by the above calculation is in a signal form that can be easily compared with a certain threshold value. Then, as shown in FIG. 5, when the motor winding temperature (T) after the filter processing exceeds the winding temperature protection threshold T1 (predetermined predetermined value), it is determined that the motor is overheated, and the motor The operation of stopping the operation is performed, and the operation of the electric compressor is stopped.

  As described above, in the present invention, it is possible to appropriately estimate the temperature of the motor winding by arithmetic processing with an inexpensive configuration without providing a temperature sensor, and by adding a temperature correction coefficient, It becomes possible to estimate more appropriately, and furthermore, by adding filtering, it becomes possible to determine the current temperature more appropriately, and to protect the motor of the electric compressor appropriately and reliably. it can.

  The control method and control device for an electric compressor according to the present invention can be applied to any system capable of detecting the discharge pressure of a refrigerant or the like, and in particular, the electric compressor used for refrigerant compression of a vehicle air conditioner. It is suitable for the control.

It is a longitudinal cross-sectional view which shows an example of the hybrid compressor used as the application object of the control method and control apparatus which concern on this invention. It is a longitudinal cross-sectional view which shows an example of the electric compressor used as the application object of the control method and control apparatus which concern on this invention. It is a circuit block diagram which shows an example of the motor drive device in this invention. It is a schematic block diagram of the freezing circuit which shows an example of arrangement | positioning of the electric compressor in this invention. It is a flowchart which shows an example of the control which concerns on this invention. It is a time chart which shows an example of increase / decrease in the motor winding temperature correction coefficient in this invention. It is explanatory drawing which shows an example of the filter process in this invention.

Explanation of symbols

A Hybrid Compressor B Electric Compressor 1 First Compression Mechanism 2 Second Compression Mechanism 10 Fixed Scroll 11 Movable Scroll 12 Working Space 13 Drive Shaft 14 Electromagnetic Clutch 15 Ball Coupling 16 Suction Port 20 Fixed Scroll 21 Movable Scroll 22 Working Space 23 Drive shaft 24 Ball coupling 25 Suction port 26 Electric motor 30 Discharge passage 31 Discharge port 32 Check valve 41 Electric motor 42 Movable scroll 43 Fixed scroll 44 Compression mechanism 51 Motor drive device 52 DC power supply 53 Capacitor 54 Semiconductor switching element 55 Inverter 56 Main control circuit 57 Inverter control circuit 58 Current sensor 61 Condenser 62 Discharge pressure sensor 63 Expansion valve 64 Evaporator

Claims (10)

From the discharge pressure Pd of the electric compressor, the motor rotational speed NEc , the motor drive device input current Iin, the temperature correction value Ta, and the proportional constant a previously obtained ,
Tc = [(a × Pd × Iin) / NEc] + Ta
And calculating the motor winding temperature Tc by calculation. The method for controlling an electric compressor according to claim 1, wherein the temperature correction value Ta is set to increase / decrease depending on the operating state of the electric compressor , increase with time when the motor rotates, and decrease when the motor stops . Ru added filtering on a result of the calculation, the control method of an electric compressor according to claim 1 or 2. The method for controlling an electric compressor according to any one of claims 1 to 3, wherein when the motor winding temperature Tc by calculation exceeds a predetermined value, it is determined that the motor is overheated and the operation of the electric compressor is stopped. The method of controlling an electric compressor according to claim 4, wherein after the operation of the electric compressor is stopped, the operation of the electric compressor is resumed when the calculated motor winding temperature Tc becomes a predetermined value or less. From the discharge pressure Pd of the electric compressor, the motor rotational speed NEc , the motor drive device input current Iin, the temperature correction value Ta, and the proportional constant a previously obtained ,
Tc = [(a × Pd × Iin) / NEc] + Ta
A control device for an electric compressor, characterized by having a calculation means for calculating a motor winding temperature Tc using The control device for an electric compressor according to claim 6, wherein the temperature correction value Ta is set so as to increase / decrease depending on an operating state of the electric compressor , increase with time when the motor rotates, and decrease when the motor stops . It said calculating means, calculation results comprises means for Ru adding filtering, the control device for an electric compressor according to claim 6 or 7. 9. The apparatus according to claim 6, further comprising a control unit that determines that the motor is overheated and stops the operation of the electric compressor when the motor winding temperature Tc calculated by the calculation unit exceeds a predetermined value. The control apparatus of the electric compressor of description. 10. The electric compressor according to claim 9, wherein after the operation of the electric compressor is stopped, the control unit resumes the operation of the electric compressor when the calculated motor winding temperature Tc becomes a predetermined value or less. Control device.

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