Electric compressor control device, electric compressor, and electric compressor control method

Abstract

To provide an electric compressor control device, etc. capable of simplifying a configuration.SOLUTION: An electric compressor control device includes: a control section for an inverter controlling a motor driving a compressor; a physical quantity calculation section calculating physical quantity that changes in accordance with a workload of the compressor, on the basis of one or a plurality of predetermined detection values obtained from the inverter; a rotational frequency acquisition section acquiring rotational frequency of the motor; a storage section storing information indicating a first threshold value changing in accordance with the rotational frequency of the motor, the first threshold value defining whether or not the physical quantity is a normal value; and a refrigerant abnormality determination section determining whether or not a refrigerant system has an abnormality by comparing the calculated physical quantity with the first threshold value, in accordance with the acquired rotational frequency.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an electric compressor control device, an electric compressor, and an electric compressor control method. [Background technology]

[0002] Patent Document 1 discloses a device that detects instantaneous current and instantaneous voltage applied to a three-phase coil of a motor and estimates motor drive torque and the like from these detected values. The device described in Patent Document 1 estimates condensation pressure, evaporation pressure, suction heating, lubrication failure, liquid compression, and the like based on the motor drive torque estimated from the detected values ​​of the instantaneous current and instantaneous voltage, for example, and the detected values ​​of the temperature of an outdoor heat exchanger and the temperature of an indoor heat exchanger in a refrigerant system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-60457 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the device described in Patent Document 1 estimates the state of the refrigerant system using the detected temperature value in the refrigerant system as described above, which has the problem that the configuration for the estimation process can be complicated.

[0005] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide an electric compressor control device, an electric compressor, and an electric compressor control method that can simplify the configuration. [Means for solving the problem]

[0006] In order to solve the above problems, the electric compressor control device disclosed herein includes an inverter control unit that controls a motor that drives a compressor, a physical quantity calculation unit that calculates a physical quantity that changes according to the workload of the compressor based on one or more predetermined detection values ​​obtained from the inverter, a rotation speed acquisition unit that acquires the rotation speed of the motor, a memory unit that stores information representing a first threshold that changes according to the rotation speed of the motor and defines whether or not the physical quantity is a normal value, and a refrigerant abnormality determination unit that determines the presence or absence of an abnormality in a refrigerant system by comparing the calculated physical quantity with the first threshold according to the acquired rotation speed.

[0007] The electric compressor according to the present disclosure includes a compressor, a motor that drives the compressor, an inverter control unit that controls the motor, a physical quantity calculation unit that calculates a physical quantity that changes according to the workload of the compressor based on one or more predetermined detection values ​​obtained from the inverter, a rotation speed acquisition unit that acquires the rotation speed of the motor, a memory unit that stores information representing a first threshold that changes according to the rotation speed of the motor and defines whether the physical quantity is a normal value or not, and a refrigerant abnormality determination unit that determines the presence or absence of an abnormality in a refrigerant system by comparing the calculated physical quantity with the first threshold according to the acquired rotation speed.

[0008] The electric compressor control method disclosed herein is a control method for an inverter that controls a motor that drives a compressor, and includes the steps of: calculating a physical quantity that changes according to the workload of the compressor based on one or more predetermined detection values ​​obtained from the inverter; acquiring a rotation speed of the motor; and determining whether or not there is an abnormality in a refrigerant system by comparing the calculated physical quantity according to the acquired rotation speed with a first threshold value that changes according to the rotation speed of the motor and defines whether or not the physical quantity is a normal value. Effect of the Invention

[0009] According to the electric compressor control device, the electric compressor, and the electric compressor control method disclosed herein, the configuration can be simplified. [Brief description of the drawings]

[0010] [Figure 1] 1 is a block diagram showing a configuration example of an electric compressor according to an embodiment of the present disclosure. FIG. [Diagram 2] FIG. 2 is a system diagram showing a configuration example of a refrigerant system of the compressor 5 shown in FIG. [Diagram 3] 2 is a schematic diagram for explaining an example of operation of the electric compressor 1 shown in FIG. 1. [Figure 4] 2 is a schematic diagram for explaining an example of operation of the electric compressor 1 shown in FIG. 1. [Diagram 5] 2 is a flowchart showing an example of the operation of the control device 3 shown in FIG. [Figure 6] 6 is a flowchart showing an example (first embodiment) of the contents of the refrigerant load abnormality determination (S108) shown in FIG. 5. [Figure 7] 6 is a flowchart showing an example (second embodiment) of the contents of the refrigerant load abnormality determination (S108) shown in FIG. 5. [Figure 8] 8 is a schematic diagram for explaining an example of the operation of the control device 3 shown in FIG. 7. FIG. [Figure 9] 6 is a flowchart showing an example (third embodiment) of the contents of the refrigerant load abnormality determination (S108) shown in FIG. 5. [Figure 10] 8 is a schematic diagram for explaining an example of the operation of the control device 3 shown in FIG. 7. FIG. [Figure 11] FIG. 1 is a schematic block diagram illustrating a configuration of a computer according to at least one embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] First Embodiment Hereinafter, an electric compressor control device, an electric compressor, and an electric compressor control method according to an embodiment of the present disclosure will be described with reference to Figs. 1 to 6. Note that the same or corresponding configurations in each drawing are designated by the same reference numerals, and the description will be omitted as appropriate. In addition, in this specification and drawings, the electric compressor is also abbreviated to electric comp.

[0012] Fig. 1 is a block diagram showing a configuration example of an electric compressor according to an embodiment of the present disclosure. Fig. 2 is a system diagram showing a configuration example of a refrigerant system of a compressor 5 shown in Fig. 1. Figs. 3 and 4 are schematic diagrams for explaining an operation example of the electric compressor 1 shown in Fig. 1. Fig. 5 is a flowchart showing an operation example of the control device 3 shown in Fig. 1. Fig. 6 is a flowchart showing an example (first embodiment) of the contents of the refrigerant load abnormality determination (S108) shown in Fig. 5.

[0013] (Electric compressor configuration) As shown in Fig. 1, an electric compressor 1 according to this embodiment includes an inverter 2, a motor 4, and a compressor 5. The electric compressor 1 shown in Fig. 1 can be, for example, an electric compressor mounted on a vehicle, such as an electric compressor for a vehicle.

[0014] The compressor 5 compresses the refrigerant in a refrigerant system 10 as shown in FIG. 2, for example. The refrigerant system 10 shown in FIG. 2 includes a condenser 11, an expansion valve 12, an evaporator 13, the compressor 5, a refrigerant pipe 14 connecting the condenser 11 and the expansion valve 12, a refrigerant pipe 15 connecting the expansion valve 12 and the evaporator 13, a refrigerant pipe 16 connecting the evaporator 13 and the compressor 5, and a refrigerant pipe 17 connecting the compressor 5 and the condenser 11. The refrigerant system 10 constitutes a refrigerant system in, for example, a vehicle air conditioning system. In the refrigerant system 10, the refrigerant circulates through the compressor 5, the condenser 11, the expansion valve 12, the evaporator 13, and the compressor 5 in that order. One end of the refrigerant pipe 16 is connected to a refrigerant suction port of the compressor 5, and one end of the refrigerant pipe 17 is connected to a refrigerant discharge port of the compressor 5. The compressor 5 compresses the refrigerant supplied from the refrigerant pipe 16 and outputs the compressed refrigerant to the refrigerant pipe 17.

[0015] 1, compressor 5 is connected to motor 4 via drive shaft 6 and is rotationally driven by motor 4. Motor 4 is, for example, an AC motor such as a three-phase brushless DC (direct current) motor, and is driven by AC power supplied from inverter 2. Motor 4 may be a sensorless type, or may have a position sensor that detects the position of the rotor.

[0016] The inverter 2 includes a bridge circuit 20, a capacitor 21, a voltage sensor 22, a current sensor 23, and a control device 3. The bridge circuit 20 is a three-phase bridge circuit including six IGBTs (Insulated Gate Bipolar Transistors) and switching units 24-29 each including six freewheeling diodes connected between the collector and emitter of each IGBT. The switching units 24-29 are controlled to be turned on or off at a predetermined timing by the control device 3, and convert a DC voltage supplied from a parallel circuit of the high-voltage battery 7 and the capacitor 21 into a three-phase AC voltage and apply it to the three-phase coils of the motor 4. The voltage sensor 22 detects the DC voltage input to the bridge circuit 20 and outputs a signal indicating the detected voltage value (detected value) to the control device 3. The current sensor 23 detects the DC current input to the bridge circuit 20 and outputs a signal indicating the detected current value (detected value) to the control device 3. The inverter 2 also has other sensors (not shown) that detect the motor current (three-phase current) which is the output current of the inverter 2, the three-phase AC voltage which is the output voltage of the inverter 2, the power element temperature, and the like.

[0017] The control device 3 can be configured, for example, using a computer such as a microcomputer, and computer peripheral circuits such as gate drive circuits for the switching units 24-29, an amplifier circuit for an output signal of the current sensor 23, and a power supply circuit. The control device 3 includes a control unit 31, a physical quantity calculation unit 32, a rotation speed acquisition unit 33, a storage unit 34, and a refrigerant abnormality determination unit 35 as a functional configuration configured by a combination of hardware such as the computer and the peripheral circuits, and software such as a program executed by the computer.

[0018] The control unit 31 controls each part of the inverter 2 (such as the bridge circuit 20 and other functional configurations in the control device 3) that controls the motor 4 that drives the compressor 5. The control unit 31 controls each part of the inverter 2 in accordance with a request from a higher-level controller 8 such as a vehicle-side controller, to, for example, operate or stop the motor 4, or control the number of revolutions (rotation speed) during operation. Furthermore, when the power element temperature / input power / input current / motor current, etc. exceed their upper limits, or when the input voltage falls outside the operable range, the control unit 31 determines that it is difficult to continue operation and stops the motor 4.

[0019] The physical quantity calculation unit 32 calculates a physical quantity Wx that changes according to the workload of the compressor 5 based on one or more predetermined detection values ​​obtained from the inverter 2 while the electric compressor 1 is in operation (i.e., while the compressor 5 is being driven). In this embodiment, the physical quantity Wx that changes according to the workload of the compressor 5 is a value calculated or estimated from one or more detection values ​​such as an element temperature, an inverter board temperature, a current, and a voltage obtained from the inverter 2, and is an amount that changes according to the workload (load) of the compressor 5. The physical quantity Wx is, for example, the motor current itself, the suction pressure, the discharge pressure, and the load torque that can be estimated from the one or more detection values, the input power of the inverter 2 calculated from the input voltage (DC voltage) and the input current (DC current), and the output power of the inverter 2 calculated from the motor current and the output voltage (three-phase AC voltage). In this embodiment, the electric compressor 1 is in operation means a state in which the motor 4 is rotating the compressor 5, and the electric compressor 1 is stopped means a state in which the motor 4 and the compressor 5 are stopped. The physical quantity calculation unit 32 calculates the physical quantity Wx, for example, in step S108 shown in FIG. 5, which will be described later.

[0020] The rotation number acquiring unit 33 acquires the rotation number of the motor 4. For example, the rotation number acquiring unit 33 acquires an estimated value of the rotation number of the motor 4 from the control unit 31, or, if the motor 4 is equipped with a position sensor, acquires a calculated value of the rotation number of the motor 4 based on the detection result of the position sensor. The rotation number acquiring unit 33 acquires the rotation number of the motor 4, for example, in step S108 shown in Fig. 5 described later.

[0021] The storage unit 34 stores first threshold information 341 and second threshold information 342. As shown in Fig. 3, the first threshold information 341 is a threshold (first threshold TH1) that changes depending on the rotation speed of the motor 4, and is information representing the first threshold TH1 that defines whether the physical quantity Wx is a normal value or not. Note that Fig. 3 shows the relationship between the rotation speed, the first threshold TH1, and the second threshold TH2, with the rotation speed of the motor 4 on the horizontal axis and the physical quantity Wx that changes depending on the workload of the compressor 5 on the vertical axis. The first threshold information 341 can be, for example, a table showing the value of the first threshold TH1 corresponding to the rotation speed, or information representing a calculation formula for calculating the value of the first threshold TH1 based on the rotation speed.

[0022] The second threshold information 342 is a threshold (second threshold TH2) that changes according to the rotation speed of the motor 4, and is information representing the second threshold TH2 that defines whether the physical quantity Wx is slightly abnormal or severely abnormal when it is not normal. The second threshold information 342 can be, for example, a table showing the value of the second threshold TH2 corresponding to the rotation speed, or information representing a calculation formula for calculating the value of the second threshold TH2 based on the rotation speed. Note that normal is a region used in normal operation. Mild abnormality is a region not used in normal operation, but where there is no possibility of failure even if operation is continued. And severe abnormality is a region where there is a possibility of failure if operation is continued.

[0023] That is, the minor abnormality is, for example, a state in which it is estimated that the compressor 5 etc. will not break down even if it is not stopped, and it is possible to continue operation, but the efficiency of operation etc. is reduced, and it is an abnormality in which the state deviates from the range expected in a normal operating environment (normal range). In this case, in the minor abnormality, it is possible to continue operation, but it is estimated that, for example, some problem has occurred. In addition, the major abnormality means, for example, a state in which it is desirable to immediately stop the compressor 5 etc. In the major abnormality, it is more likely that some problem has occurred, and it is not desirable to continue operation. In addition, in FIG. 3, the width that increases according to the rotation speed of the first threshold TH1 and the second threshold TH2 shown by hatching is the width of the hysteresis of the threshold.

[0024] In the electric compressor 1 of this embodiment, when compressing the refrigerant, the compressor 5 generates heat due to mechanical loss, but the compressor 5 is prevented from becoming abnormally hot by cooling with the refrigerant. However, if an abnormality occurs in the refrigerant pipes 14 to 17 or the like and the flow of the refrigerant is obstructed, the compressor 5 is not cooled by the refrigerant and generates heat. However, if the electric compressor 1 does not have a sensor that detects that the flow of the refrigerant is obstructed, it cannot directly detect this abnormality. In such a case, if the electric compressor 1 continues to operate in accordance with a request from a higher-level controller 8 such as a vehicle-side controller, the compressor 5 or the like may eventually break down.

[0025] Therefore, as shown in FIG. 4, the electric compressor 1 of this embodiment uses the characteristic that the workload of the compressor 5 decreases when the flow of the refrigerant is obstructed to determine whether or not there is an abnormality in the refrigerant system 10 based on the physical quantity Wx that changes according to the workload of the compressor 5. If there is an abnormality, the electric compressor 1 stops the operation of the electric compressor 1. FIG. 4 shows the time on the horizontal axis and the characteristic value related to the operation of the compressor 5 on the vertical axis, and shows the time change of each characteristic value before and after the state of the refrigerant piping changes from normal to abnormal (state in which the flow is obstructed). The characteristic values ​​related to the operation of the compressor 5 shown in FIG. 4 are, from the top, the mechanical temperature (temperature of the mechanism of the compressor 5), the suction pressure, the discharge pressure, and the physical quantity Wx. In the example shown in FIG. 4, when the state changes from normal to abnormal, the mechanical temperature gradually increases and then becomes saturated at a certain temperature, and the suction pressure, the discharge pressure, and the physical quantity Wx suddenly decrease and then maintain low values.

[0026] The refrigerant abnormality determination unit 35 determines whether or not there is an abnormality in the refrigerant system 10 by comparing the physical quantity Wx calculated by the physical quantity calculation unit 32 with a first threshold value TH1 according to the rotation speed acquired by the rotation speed acquisition unit 33. The refrigerant abnormality determination unit 35 can also determine whether the refrigerant system 10 is normal, slightly abnormal, or severely abnormal by comparing the calculated physical quantity Wx with a first threshold value TH1 and a second threshold value TH2 according to the acquired rotation speed. The refrigerant abnormality determination unit 35 can also determine that operation can be continued when determining that there is a normal or mild abnormality, and can determine that operation cannot be continued when determining that there is a severe abnormality.

[0027] (Electric compressor operation) Next, an example of the operation of the electric compressor 1 shown in Fig. 1 will be described with reference to Fig. 5 and Fig. 6. The process shown in Fig. 5 is repeatedly executed at a constant cycle while the electric compressor 1 is activated. The process shown in Fig. 6 is executed in step S108 in Fig. 5.

[0028] When power is supplied to the electric compressor 1 and the control device 3 is started, the control device 3 starts the process shown in FIG. 5. In the process shown in FIG. 5, the control unit 31 first judges whether or not there is a suspicion of failure in the inverter 2, the motor 4, or the compressor 5 based on the detection signals of various sensors, the execution result of the internal diagnosis process, and the like (step S101). On the other hand, if the control unit 31 judges that there is a suspicion of failure (if "Yes" in step S101), the control device 3 stops operation (step S112) and ends the process shown in FIG. 5. On the other hand, if it is judged that there is no suspicion of failure (if "No" in step S101), the control unit 31 checks various detection values ​​such as current, voltage, power, and temperature (step S102). Next, the control unit 31 judges whether or not the various detection values ​​are within the operable range of the electric compressor 1 (step S103). If the electric compressor 1 is operable (if "Yes" in step S103), the control unit 31 judges whether or not there is an operation request from the upper controller 8 (step S104).

[0029] If there is an operation request ("Yes" in step S104), the control unit 31 determines whether or not the compressor is stopped due to a refrigerant load abnormality determination (step S105). "Stopped due to a refrigerant load abnormality determination" here means that the refrigerant load abnormality determination (step S108) has determined that the electric compressor 1 cannot continue to operate, and the electric compressor 1 has been stopped ("No" in step S110 -> electric compressor 1 has been stopped in step S111).

[0030] On the other hand, if the compressor is not stopped due to the refrigerant load abnormality determination ("No" in step S105), the control unit 31 determines whether the electric compressor 1 is in operation (step S106), and if the compressor is not in operation ("No" in step S106), the control unit 31 starts operation of the electric compressor 1 (step S107) and executes the refrigerant load abnormality determination (step S108). On the other hand, if the compressor is in operation ("Yes" in step S106), the control unit 31 executes the refrigerant load abnormality determination (step S108).

[0031] If the operation is stopped due to the refrigerant load abnormality determination ("Yes" in step S105), the control unit 31 determines whether the stop due to the refrigerant load abnormality determination has continued for a predetermined time (step S109). If the operation has continued for the predetermined time ("Yes" in step S109), the control unit 31 starts the operation of the electric compressor 1 (step S107) and executes the refrigerant load abnormality determination (step S108).

[0032] In the refrigerant load abnormality determination in step S108, the refrigerant abnormality determination unit 35 compares the physical quantity Wx, which changes according to the workload of the compressor 5 calculated by the physical quantity calculation unit 32 based on the rotation speed acquired by the rotation speed acquisition unit 33, with the first threshold value TH and the second threshold value TH2 described with reference to FIG. 3, and determines whether the electric compressor 1 can continue to operate. In this embodiment, the refrigerant abnormality determination unit 35 compares the physical quantity Wx with the first threshold value TH and the second threshold value TH2 while the electric compressor 1 is operating, and determines whether the electric compressor 1 can continue to operate. Therefore, when the electric compressor 1 is not operating (if "No" in step S106), the control unit 31 starts the operation of the electric compressor 1 (step S107) and then executes the refrigerant load abnormality determination (step S108).

[0033] In this embodiment, when the refrigerant abnormality determination unit 35 determines that operation cannot be continued in the refrigerant load abnormality determination in step S108 and the control unit 31 stops the electric compressor 1 ("No" in step S110 -> "stops the electric compressor 1" in step S111), the control device 3 executes the refrigerant load abnormality determination (step S108) again when the stopped state continues for a predetermined time ("Yes" in step S109). By these processes, when it is determined that operation cannot be continued in the refrigerant load abnormality determination in step S108, the control device 3 executes the refrigerant load abnormality determination in step S108 again after the predetermined time has continued, and can operate the electric compressor 1 when the flow of the refrigerant is restored or the previous determination was an erroneous determination. For example, a limit may be set on the number of times that the refrigerant load abnormality determination is performed again after the predetermined time has continued, or the predetermined time may be changed depending on the number of repetitions.

[0034] After the refrigerant abnormality determination unit 35 executes the refrigerant load abnormality determination in step S108, the control unit 31 determines whether or not the refrigerant abnormality determination unit 35 determines that operation can be continued (step S110). On the other hand, if it is determined that operation can be continued (if "Yes" in step S110), the control unit 31 executes the determination process of step S101 again, and on the other hand, if it is determined that operation cannot be continued (if "No" in step S110), the control unit 31 stops the electric compressor 1 (step S111) and executes the determination process of step S101 again.

[0035] Furthermore, if operation is not possible (if "No" in step S103), if there is no request for operation (if "No" in step S104), or if the stopped state has not continued for a predetermined time (if "No" in step S109), the control unit 31 stops the electric compressor 1 (step S111) and executes the judgment process of step S101 again.

[0036] In the refrigerant load abnormality determination in step S108, as shown in Fig. 6, the refrigerant abnormality determination unit 35 first determines whether or not the refrigerant load abnormality determination is possible (step S201). In step S201, the refrigerant abnormality determination unit 35 determines that the determination is not possible when, for example, the rotation speed of the motor 4 is not stable when the motor 4 is started (step S201: No), and determines that the operation can be continued provisionally in order to continue the operation until the rotation speed stabilizes (step S204), and ends the refrigerant load abnormality determination process shown in Fig. 6. On the other hand, when it is determined that the refrigerant load abnormality determination is possible (step S201: Yes), the refrigerant abnormality determination unit 35 compares the calculated physical quantity Wx with the first threshold value TH1 and the second threshold value TH2 according to the acquired rotation speed to determine the presence or absence of an abnormality in the refrigerant system (step S202).

[0037] Next, the refrigerant abnormality determination unit 35 determines whether or not the determination result of step S202 was a severe abnormality (step S203). On the other hand, if it is a severe abnormality (if "Yes" in step S203), the refrigerant abnormality determination unit 35 determines that operation cannot be continued (step S205) and ends the refrigerant load abnormality determination process shown in Fig. 6. On the other hand, if it is not a severe abnormality (if "No" in step S203), the refrigerant abnormality determination unit 35 determines that operation can be continued (step S204) and ends the refrigerant load abnormality determination process shown in Fig. 6.

[0038] (Action and effect) The electric compressor 1 or control device 3 according to this embodiment can determine the presence or absence of a refrigerant abnormality, such as obstruction of the flow of the refrigerant compressed by the compressor 5, by comparing the physical quantity Wx, which is a value calculated or estimated from one or more detected values ​​such as the current, voltage, element temperature, etc. obtained from the inverter 2 and changes according to the workload (load) of the compressor 5, with thresholds (first threshold TH1 and second threshold TH2) which change according to the rotation speed of the motor 4. These detected values ​​can be easily obtained, so the configuration of the electric compressor 1 can be easily simplified.

[0039] <Second embodiment> Hereinafter, an electric compressor according to a second embodiment of the present disclosure will be described with reference to FIG. 7 and FIG. 8. The configuration and operation of the electric compressor according to the second embodiment are the same as those of the electric compressor according to the first embodiment with respect to the parts described with reference to FIG. 1 to FIG. 5, and the content of the refrigerant load abnormality determination process according to the first embodiment described with reference to FIG. 6 is different from the content of the refrigerant load abnormality determination process according to the second embodiment shown in FIG. 7. FIG. 7 is a flowchart showing an example (second embodiment) of the content of the refrigerant load abnormality determination (S108) shown in FIG. 5. FIG. 8 is a schematic diagram for explaining an example of the operation of the control device 3 shown in FIG. 7, in which the horizontal axis is time and the vertical axis is a physical quantity Wx that changes according to the amount of work, and shows the time change of the physical quantity Wx when the rotation speed is constant.

[0040] (Electric compressor operation) The refrigerant load abnormality determination process (S108 in FIG. 5) of the second embodiment shown in FIG. 7 is obtained by adding new processes of steps S206 and S207 to the refrigerant load abnormality determination process (S108 in FIG. 5) of the first embodiment shown in FIG. 6.

[0041] Hereinafter, in the second embodiment, a process different from the first embodiment will be described. In the refrigerant load abnormality determination process shown in FIG. 7, when a severe abnormality is determined (when "Yes" in step S203), the refrigerant abnormality determination unit 35 calculates the time T1 during which the minor abnormality was maintained (step S206). Next, the refrigerant abnormality determination unit 35 determines whether the time T1 is greater than the reference value T1min of the maintenance time set as the shortest value (step S207). On the other hand, when the time T1 is greater than the reference value T1min (when "Yes" in step S207), the refrigerant abnormality determination unit 35 determines that operation can be continued (step S204), and ends the refrigerant load abnormality determination process shown in FIG. 7. On the other hand, when the time T1 is not greater than the reference value T1min (when "No" in step S207), the refrigerant abnormality determination unit 35 determines that operation cannot be continued (step S205), and ends the refrigerant load abnormality determination process shown in FIG. 7. In the second embodiment, when a severe abnormality is determined, it is determined that operation cannot be continued if the time T1 spent in the mild abnormality state is less than or equal to a reference value T1min, and it is determined that operation can be continued if the time T1 spent in the mild abnormality state is greater than the reference value T1min.

[0042] The time T1 during which the minor abnormality persists is the time from time t1s when the minor abnormality is first determined to be present to time t1e when the minor abnormality is last determined to be present before the major abnormality is determined, as shown in Fig. 8. If this time T1 is short, it can be determined that the change in the physical quantity Wx is rapid. Note that if the determination result in step S202 is a major abnormality from the beginning, the time T1 can be set to zero.

[0043] In the electric compressor 1 of the second embodiment, as in the electric compressor 1 of the first embodiment, a refrigerant load abnormality determination is performed while the electric compressor 1 is operating, and if it is determined that continued operation is impossible, the compressor is stopped. Also, in the electric compressor 1 of the second embodiment, as in the electric compressor 1 of the first embodiment, in the refrigerant load abnormality determination, the physical quantity Wx, which changes according to the workload, is determined to be normal, mildly abnormal, or severely abnormal, and if it is normal or mildly abnormal, it is determined that continued operation is possible because there is no risk of failure even if operation is continued.

[0044] On the other hand, in the electric compressor 1 of the second embodiment, unlike the electric compressor 1 of the first embodiment, if the physical quantity Wx that changes according to the current workload is determined to correspond to a severe abnormality and if the physical quantity Wx that changes according to the workload suddenly changes from normal to a severe abnormality, it is determined that operation cannot be continued due to a refrigerant abnormality.

[0045] In the electric compressor 1 of the second embodiment, the index of the rapidity of the change is determined based on the time T1 at which the physical quantity Wx, which changes according to the workload, is determined to have a value corresponding to a minor abnormality, and if that time is shorter than a reference value T1min, it is determined to be a rapid change.

[0046] (Action and effect) According to the second embodiment, if the flow of the refrigerant is obstructed, it is determined that continued operation is impossible, and damage to the mechanism due to abnormal heating can be prevented.

[0047] <Third embodiment> Hereinafter, an electric compressor according to a third embodiment of the present disclosure will be described with reference to Figs. 9 and 10. The configuration and operation of the electric compressor according to the third embodiment are the same as those of the electric compressor according to the first and second embodiments, as described with reference to Figs. 1 to 5, and the content of the refrigerant load abnormality determination process according to the first and second embodiments described with reference to Figs. 6 and 7 is different from the content of the refrigerant load abnormality determination process according to the third embodiment shown in Fig. 9. Fig. 9 is a flowchart showing an example of the content of the refrigerant load abnormality determination (S108) shown in Fig. 5 (third embodiment). Fig. 10 is a schematic diagram for explaining an example of the operation of the control device 3 shown in Fig. 9, in which the horizontal axis is time and the vertical axis is a physical quantity Wx that changes depending on the amount of work, and shows the time change of the physical quantity Wx when the rotation speed is constant.

[0048] (Electric compressor operation) The refrigerant load abnormality determination process (S108 in FIG. 5) of the third embodiment shown in FIG 9 is obtained by adding new processes of steps S208 and S209 to the refrigerant load abnormality determination process (S108 in FIG. 5) of the second embodiment shown in FIG 7. Below, the processes in the third embodiment that differ from the second embodiment will be described.

[0049] In the refrigerant load abnormality determination process shown in Fig. 9, when the time T1 is greater than the reference value T1min (when "Yes" in step S207), the refrigerant abnormality determination unit 35 calculates the time T2 during which the severe abnormality remains (step S208) and determines whether the time T2 is less than the reference value T2max of the longest residence time (step S209). On the other hand, when the time T2 is less than the reference value T2max of the longest residence time (when "Yes" in step S209), the refrigerant abnormality determination unit 35 determines that operation can be continued (step S204) and ends the refrigerant load abnormality determination process shown in Fig. 9. On the other hand, when the time T2 is equal to or greater than the reference value T2max of the longest residence time (when "No" in step S209), the refrigerant abnormality determination unit 35 determines that operation cannot be continued (step S205) and ends the refrigerant load abnormality determination process shown in Fig. 9.

[0050] The time T2 during which the severe abnormality persists is the time during which the severe abnormality persists after it has been determined to be severely abnormal, as shown in FIG. 10, for example.

[0051] In the second embodiment, it is determined that the operation cannot be continued only when the duration T1 of the minor abnormality is equal to or less than the reference value T1min. In this case, depending on the state in which the flow of the refrigerant is obstructed, the decrease in the physical quantity Wx that changes according to the workload may be slower than expected, and the duration T1 of the minor abnormality may not become equal to or less than the reference value T1min. In such a case, it is also impossible to continue the operation of the electric compressor 1 for a long time, so it is necessary to determine that the operation cannot be continued. Therefore, in the third embodiment, in addition to the second embodiment, even if the physical quantity Wx that changes according to the workload becomes a severe abnormal value and does not change suddenly, it is determined that the operation cannot be continued based on the time T2 at which the physical quantity Wx that changes according to the workload is determined to be a value corresponding to a severe abnormality, and if the time is longer than the reference value T2max, it is determined that the operation cannot be continued. Note that, when the reference value T2max is set in order to install the electric compressor 1 incorporating this protection control in an actual vehicle, it is preferable to change the reference value T2max according to the rotation speed, and set a shorter time at a high rotation speed than at a low rotation speed.

[0052] (Action and effect) According to the third embodiment, even if the change in the physical quantity Wx that changes according to the amount of work when the flow of the refrigerant is obstructed is gradual, it is possible to determine that it is impossible to continue operating the electric compressor.

[0053] <Modifications of each embodiment> In the first, second and third embodiments, the thresholds (first threshold TH1 and second threshold TH2) for determining whether the physical quantity Wx, which changes according to the workload, is normal, slightly abnormal or severely abnormal are changed according to the rotation speed. Also, for example, the range corresponding to normality is set to the region used in normal operation, but this region changes according to the ambient temperature of the electric compressor 1. Therefore, in order to more accurately determine whether the physical quantity Wx is normal, slightly abnormal or severely abnormal, these thresholds (first threshold TH1 and second threshold TH2) may be corrected according to the ambient temperature. The ambient temperature may be obtained, for example, by receiving it from the upper controller 8, adding a sensor to the electric compressor 1, or estimating it from a sensor in the electric compressor 1.

[0054] The electric compressor 1 can be used not only for cooling but also for heating heat pumps. However, the relationship between the rotation speed and pressure during operation is different between cooling and heating. Therefore, it is desirable to set up multiple criteria for determining whether the condition is normal, mildly abnormal, or severely abnormal, which are determined by the rotation speed and the physical quantity Wx that changes according to the amount of work shown in Figure 3, in advance so that they can be switched between cooling and heating.

[0055] In addition, during low-speed operation, even if a severe abnormality continues, it may not result in a breakdown. Therefore, a lower limit of the rotation speed for determining whether the refrigerant load is abnormal may be set.

[0056] According to the above modification, for example, it is possible to more accurately distinguish between normality, mild abnormality, and severe abnormality.

[0057] (Other embodiments) Although the embodiment of the present disclosure has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like within the scope of the present disclosure are also included. For example, the first threshold TH1 and the second threshold TH2 may have values ​​that change stepwise, for example.

[0058] Computer Configuration FIG. 11 is a schematic block diagram illustrating a computer configuration according to at least one embodiment. The computer 90 comprises a processor 91, a main memory 92, a storage 93, and an interface 94. The above-mentioned control device 3 is implemented in a computer 90. The operations of the above-mentioned processing units are stored in the form of a program in a storage 93. The processor 91 reads the program from the storage 93, loads it in a main memory 92, and executes the above-mentioned processing in accordance with the program. The processor 91 also secures storage areas in the main memory 92 corresponding to the above-mentioned storage units in accordance with the program.

[0059] The program may be for realizing a part of the functions to be performed by the computer 90. For example, the program may be for realizing the functions by combining with other programs already stored in the storage or by combining with other programs implemented in other devices. In other embodiments, the computer may include a custom LSI (Large Scale Integrated Circuit) such as a PLD (Programmable Logic Device) in addition to or instead of the above configuration. Examples of PLDs include PAL (Programmable Array Logic), GAL (Generic Array Logic), CPLD (Complex Programmable Logic Device), and FPGA (Field Programmable Gate Array). In this case, some or all of the functions realized by the processor may be realized by the integrated circuit.

[0060] Examples of the storage 93 include a hard disk drive (HDD), a solid state drive (SSD), a magnetic disk, a magneto-optical disk, a compact disc read only memory (CD-ROM), a digital versatile disc read only memory (DVD-ROM), and a semiconductor memory. The storage 93 may be an internal medium directly connected to the bus of the computer 90, or an external medium connected to the computer 90 via an interface 94 or a communication line. In addition, when the program is distributed to the computer 90 via a communication line, the computer 90 that receives the program may load the program into the main memory 92 and execute the above-mentioned process. In at least one embodiment, the storage 93 is a non-transitory tangible storage medium.

[0061] <Additional Notes> The control device 3 described in each embodiment can be understood, for example, as follows.

[0062] (1) An electric compressor control device (control device 3) according to a first aspect includes a control unit 31 of an inverter 2 that controls a motor 4 that drives a compressor 5, a physical quantity calculation unit 32 that calculates a physical quantity Wx that changes according to the workload of the compressor 5 based on one or more predetermined detection values ​​obtained from the inverter 2 (the detection value of the voltage sensor 22, the detection value of the current sensor 23, etc.), a rotation speed acquisition unit 33 that acquires the rotation speed of the motor 4, a memory unit 34 that stores information (first threshold information 341) representing a first threshold TH1 that changes according to the rotation speed of the motor 4 and defines whether the physical quantity Wx is a normal value or not, and a refrigerant abnormality determination unit 35 that determines the presence or absence of an abnormality in the refrigerant system 10 by comparing the calculated physical quantity Wx with the first threshold TH1 value according to the acquired rotation speed.

[0063] According to the electric compressor control device (control device 3) of the first aspect, the state of the refrigerant system 10 can be estimated without using a detected value of the temperature in the refrigerant system 10, so that the configuration can be easily simplified.

[0064] (2) An electric compressor control device (control device 3) according to a second aspect is the electric compressor control device (control device 3) of (1), wherein the memory unit 34 further stores information (second threshold information 342) representing a second threshold value TH2 that changes according to the rotation speed of the motor 4 and defines whether the physical quantity Wx is mildly abnormal or severely abnormal when it is not normal, and the refrigerant abnormality determination unit 35 determines whether the refrigerant system 10 is normal, mildly abnormal, or severely abnormal by comparing the calculated physical quantity Wx with the first threshold value TH1 and the second threshold value TH2 according to the acquired rotation speed.

[0065] According to the electric compressor control device (control device 3) of the second aspect, it is possible to distinguish between a minor abnormality and a major abnormality.

[0066] (3) The electric compressor control device (control device 3) according to a third aspect is the electric compressor control device (control device 3) of (2), in which the refrigerant abnormality determination unit 35 determines that operation can be continued (S204) if it determines that there is a normal or minor abnormality, and determines that operation cannot be continued (S205) if it determines that there is a major abnormality.

[0067] According to the electric compressor control device (control device 3) of the third aspect, it is possible to continue operation in the event of a minor abnormality.

[0068] (4) The electric compressor control device (control device 3) according to a fourth aspect is the electric compressor control device (control device 3) of (2), in which the refrigerant abnormality determination unit 35 determines that operation cannot be continued (S205) when it determines that a severe abnormality has occurred and the time T1 from when it determines that a minor abnormality has occurred to when it determines that a severe abnormality has occurred is shorter than a first time (T1min).

[0069] According to the electric compressor control device (control device 3) of the fourth aspect, it is possible to determine that continuation of operation is impossible (S205) when the change in the physical quantity Wx is rapid.

[0070] (5) The electric compressor control device (control device 3) according to the fifth aspect is the electric compressor control device (control device 3) of (4), wherein, when the refrigerant abnormality determination unit 35 determines that a severe abnormality has occurred, it determines that continued operation is impossible (S205) if the time T1 from when the minor abnormality has been determined to when the severe abnormality has been determined is shorter than the first time (T1min), and it determines that continued operation is impossible (S205) if the time T2 from when the severe abnormality has been determined to be occurred is longer than a second time (T2max).

[0071] According to the electric compressor control device (control device 3) of the fifth aspect, even if the change in the physical quantity Wx is not rapid, it can be determined that continued operation is impossible (S205) if the severe abnormality has continued for a long period of time.

[0072] (6) The sixth aspect of the electric compressor control device (control device 3) is the electric compressor control device (control device 3) of (5), wherein the second time (T2max) is determined to be short when the rotation speed of the motor 4 is high and to be long when the rotation speed of the motor 4 is low.

[0073] According to the electric compressor control device (control device 3) of the sixth aspect, the time until it is determined that the electric compressor 1 cannot continue to operate can be set according to the possibility of a malfunction occurring in the electric compressor 1.

[0074] (7) An electric compressor control device (control device 3) according to a seventh aspect is the electric compressor control device (control device 3) of (1) to (6), in which the physical quantity is an input power or an output power of the inverter 2.

[0075] (M1) The electric compressor control method according to aspect M1 is a control method for an inverter 2 that controls a motor 4 that drives a compressor 5, and includes a step (S108, etc.) of calculating a physical quantity Wx that changes according to the workload of the compressor 5 based on one or more predetermined detection values ​​obtained from the inverter 2, a step (S108, etc.) of acquiring the rotation speed of the motor 4, and a step (S202) of determining whether or not there is an abnormality in the refrigerant system by comparing the calculated physical quantity Wx with a first threshold value TH1 that changes according to the rotation speed of the motor 4 and defines whether or not the physical quantity Wx is a normal value, according to the acquired rotation speed.

[0076] (M2) In the electric compressor control method according to the aspect M2, the physical quantity is an input power or an output power of the inverter. [Explanation of symbols]

[0077] 1 Electric compressor 2 Inverter 3. Control device 4 Motor 5. Compressor 31 Control Unit 32 Physical quantity calculation section 33 Rotation speed acquisition unit 34 Storage section 35 Refrigerant abnormality determination unit

Claims

1. an inverter control unit that controls a motor that drives the compressor; a physical quantity calculation unit that calculates a physical quantity that changes according to a workload of the compressor based on one or more predetermined detection values ​​obtained from the inverter; A rotation speed acquisition unit that acquires the rotation speed of the motor; a storage unit configured to store information representing a first threshold value that changes depending on a rotation speed of the motor and that defines whether the physical quantity is a normal value; and a refrigerant abnormality determination unit that determines whether or not there is an abnormality in the refrigerant system by comparing the calculated physical amount with the first threshold value according to the acquired rotation speed; Equipped with the storage unit further stores information representing a second threshold value that changes depending on a rotation speed of the motor, the second threshold value defining whether a minor abnormality or a major abnormality occurs when the physical quantity is not normal; the refrigerant abnormality determination unit determines whether the refrigerant system is normal, has a mild abnormality, or has a severe abnormality by comparing the calculated physical quantity with the first threshold value and the second threshold value according to the acquired rotation speed; When the refrigerant abnormality determination unit determines that a severe abnormality has occurred, it determines that operation cannot be continued if a time period from when the refrigerant abnormality has been determined to be minor to when the refrigerant abnormality has been determined to be severe is shorter than a first time. Electric compressor control device.

2. The refrigerant abnormality determination unit determines that operation can be continued when it determines that the refrigerant abnormality is normal or a minor abnormality, and determines that operation cannot be continued when it determines that the refrigerant abnormality is a major abnormality. The electric compressor control device according to claim 1.

3. When the refrigerant abnormality determination unit determines that a severe abnormality has occurred, it determines that operation cannot be continued if the time from when the refrigerant abnormality has been determined to be minor to when the refrigerant abnormality has been determined to be severe is shorter than the first time, and it determines that operation cannot be continued if the time from when the refrigerant abnormality has been determined to be severe is longer than a second time. The electric compressor control device according to claim 1.

4. The second time is determined to be short when the rotation speed of the motor is high and to be long when the rotation speed of the motor is low. The electric compressor control device according to claim 3.

5. The physical quantity is an input power or an output power of the inverter. The electric compressor control device according to any one of claims 1 to 4.

6. A compressor and A motor that drives the compressor; A control unit of an inverter that controls the motor; a physical quantity calculation unit that calculates a physical quantity that changes according to a workload of the compressor based on one or more predetermined detection values ​​obtained from the inverter; A rotation speed acquisition unit that acquires the rotation speed of the motor; a storage unit configured to store information representing a first threshold value that changes depending on a rotation speed of the motor and that defines whether the physical quantity is a normal value; and a refrigerant abnormality determination unit that determines whether or not there is an abnormality in the refrigerant system by comparing the calculated physical amount with the first threshold value according to the acquired rotation speed; Equipped with the storage unit further stores information representing a second threshold value that changes depending on a rotation speed of the motor, the second threshold value defining whether a minor abnormality or a major abnormality occurs when the physical quantity is not normal; the refrigerant abnormality determination unit determines whether the refrigerant system is normal, has a mild abnormality, or has a severe abnormality by comparing the calculated physical quantity with the first threshold value and the second threshold value according to the acquired rotation speed; When the refrigerant abnormality determination unit determines that a severe abnormality has occurred, it determines that operation cannot be continued if a time period from when the refrigerant abnormality has been determined to be minor to when the refrigerant abnormality has been determined to be severe is shorter than a first time. Electric compressor.

7. The physical quantity is an input power or an output power of the inverter. The electric compressor according to claim 6.

8. A method for controlling an inverter that controls a motor that drives a compressor, comprising the steps of: calculating a physical quantity that changes according to a workload of the compressor based on one or more predetermined detection values ​​obtained from the inverter; acquiring a rotation speed of the motor; determining whether or not there is an abnormality in the refrigerant system by comparing the calculated physical quantity with a first threshold value that varies according to the rotation speed of the motor, the first threshold value defining whether or not the physical quantity is a normal value, according to the acquired rotation speed; Including, In the step of determining the presence or absence of an abnormality, the calculated physical quantity is compared with the first threshold value and a second threshold value that changes according to the rotation speed of the motor and defines whether the abnormality is mild or severe when the physical quantity is not normal, thereby determining whether the refrigerant system is normal, mildly abnormal, or severely abnormal, according to the acquired rotation speed; When it is determined that a serious abnormality has occurred, if the time from when it is determined that a minor abnormality has occurred to when it is determined that a serious abnormality has occurred is shorter than a first time, it is determined that it is impossible to continue operation. A method for controlling an electric compressor.

9. The physical quantity is an input power or an output power of the inverter. The method for controlling an electric compressor according to claim 8.

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