JP6197762B2 - Electric compressor - Google Patents

Description

  The present invention relates to an electric compressor.

  Conventionally, a housing into which a refrigerant is sucked, a compression unit that is accommodated in the housing and compresses the refrigerant, an electric motor that is accommodated in the housing and drives the compression unit, and a drive circuit that drives the electric motor, An electric compressor provided is known (see, for example, Patent Document 1). Patent Document 1 describes that a drive circuit is attached to the outer surface of the housing, and the drive circuit is cooled by heat exchange between the refrigerant and the drive circuit via the housing. Has been. Furthermore, for example, Patent Document 2 describes that an electric compressor is used for a heat pump that performs heating.

JP 2003-324900 A JP 2011-11686 A

  Here, excessive heat generation may occur in the electric motor depending on, for example, the current value and the rotation speed of the electric motor. In addition, when the electric compressor is operated under conditions where the ambient temperature around the electric compressor or the intake refrigerant temperature that is the refrigerant sucked into the housing is low, the temperature of the drive circuit may become excessively low. is there. In this case, for example, the temperature of the drive circuit may become lower than the lower limit value of the operation guarantee range of the drive circuit, and an abnormality may occur in the drive circuit.

  In particular, when the drive circuit is operating to drive the drive motor, heat related to power loss is generated in the drive circuit. However, when the operation of the drive circuit stops, heat related to power loss does not occur in the drive circuit. For this reason, when the operation of the drive circuit stops, the drive circuit may be cooled by the refrigerant sucked just before the stop, and the temperature of the drive circuit may become excessively low.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide an electric compressor that can suppress the temperature of a drive circuit from becoming excessively low.

  An electric compressor that achieves the above object includes a housing into which a refrigerant is sucked, a compression part that is accommodated in the housing and compresses and discharges the refrigerant, and is accommodated in the housing and drives the compression part. An electric motor, a drive circuit that is thermally coupled to the housing and drives the electric motor, a temperature measuring unit that measures the temperature of the drive circuit, and the drive circuit to control the electric motor A control unit, wherein the control unit has a current value of the electric motor equal to or greater than a predetermined threshold current value during rotation of the electric motor, and a rotation number of the electric motor is predetermined. A temperature stop control unit for stopping the electric motor when the temperature is equal to or lower than the threshold rotation number, and a temperature of the drive circuit measured by the temperature measurement unit during the rotation of the electric motor. And a low temperature control unit that reduces the rotational speed of the electric motor when the temperature falls below a predetermined threshold temperature, and when the rotational speed of the electric motor is reduced by the low temperature control unit, The high temperature stop control unit does not stop the electric motor.

  According to such a configuration, since the control unit includes the high-temperature stop control unit, excessive heat generation of the electric motor can be suppressed. Further, when the temperature of the drive circuit becomes equal to or lower than the threshold temperature, the rotation speed of the electric motor decreases. Thereby, since the refrigerant | coolant flow rate suck | inhaled in a housing is reduced, cooling of the drive circuit by a refrigerant | coolant is reduced. Therefore, it can suppress that the temperature of a drive circuit becomes low too much. In addition, since the temperature of the drive circuit during rotation of the electric motor can be kept high to some extent, even when the heat generation of the drive circuit is stopped due to the stop of the electric motor, the temperature of the drive circuit is It can suppress becoming low too much.

  In particular, when the rotational speed of the electric motor is reduced by the low temperature control unit, the electric motor is not stopped by the high temperature stop control unit. Thereby, the rotation speed of an electric motor can be made below into a threshold rotation speed. Therefore, the refrigerant flow rate may be reduced as compared with the case where the electric motor is stopped by the high temperature stop control unit. Further, under a relatively low temperature condition where the temperature of the drive circuit is equal to or lower than the threshold temperature, excessive heat generation is unlikely to occur in the electric motor, and thus the high temperature stop control unit does not stop the electric motor. Is unlikely to occur. Therefore, it can suppress suitably that the temperature of a drive circuit becomes low too much.

  In the electric compressor, the control unit may not stop the electric motor by the high-temperature stop control unit when the temperature of the drive circuit is equal to or lower than a prohibition temperature that is higher than the threshold temperature. According to such a configuration, the electric motor is not stopped by the high temperature stop control unit at a stage before the decrease in the rotation speed by the low temperature control unit is started. As a result, it is possible to avoid the inconvenience that the electric motor is stopped by the high temperature stop controller due to the rotation speed being reduced by the low temperature controller.

  With respect to the electric compressor, the controller has a temperature equal to or higher than a release temperature at which the temperature of the drive circuit is higher than the threshold temperature in a situation where the rotation speed of the electric motor is reduced by the low temperature controller. At this time, the decrease in the rotational speed of the electric motor by the low temperature control unit may be canceled. According to such a configuration, when the temperature of the drive circuit reaches the release temperature in a situation where the rotation speed of the electric motor is reduced by the low temperature control unit, the decrease in the rotation speed of the electric motor by the low temperature control unit is released. Thereby, since it becomes possible to raise the rotation speed of an electric motor, a refrigerant | coolant flow volume can be enlarged.

  In the electric compressor, the control unit has a temperature equal to or lower than a low temperature stop temperature that is lower than the threshold temperature in a state where the low temperature control unit reduces the rotation speed of the electric motor. It is preferable that a low-temperature stop control unit that stops the electric motor after gradually reducing the rotational speed of the electric motor is provided. Depending on the intake refrigerant temperature or the like, the temperature of the drive circuit may be lower than the threshold temperature even when the rotational speed is decreased by the low temperature control unit. On the other hand, according to the present configuration, when the electric motor has a temperature lower than the threshold temperature that is lower than the threshold temperature in a situation where the rotation speed is being reduced by the low temperature control unit, Decelerate gradually before stopping. In this case, during the deceleration of the electric motor, the refrigerant flow rate is reduced, while the operation of the drive circuit is continued, so the temperature of the drive circuit tends to increase. Thereby, the electric motor can be stopped in a state where the temperature of the drive circuit is higher than the low temperature stop temperature. Therefore, it can suppress that the temperature of a drive circuit becomes low too much due to the temperature fall of the drive circuit accompanying the stop of an electric motor.

  In particular, the electric motor is not stopped by the high temperature stop control unit while the rotation speed of the electric motor is being reduced by the low temperature stop control unit. Thereby, even if the current value of the electric motor is equal to or greater than the threshold current value, the rotation speed of the electric motor can be reduced to a threshold rotation speed or less. Therefore, since the electric motor can be stopped after further increasing the temperature of the drive circuit, it is possible to suppress the temperature of the drive circuit from being excessively lowered.

  For the electric compressor, the drive circuit has a switching element that operates normally when the temperature is equal to or higher than a predetermined operating lower limit temperature, and the electric motor is turned on when the switching element is periodically turned ON / OFF. Preferably, the threshold temperature is set higher than the operation lower limit temperature. According to such a configuration, since the rotation speed is reduced by the low temperature control unit before the temperature of the drive circuit reaches the operation lower limit temperature, it is possible to suppress the temperature of the drive circuit from approaching the operation lower limit temperature. Thereby, it can suppress that a switching element becomes lower than operating minimum temperature.

  According to this invention, it can suppress that the temperature of a drive circuit becomes low too much.

The schematic diagram which shows the outline | summary of a heat pump. The circuit diagram of an inverter. The graph for demonstrating an operation area | region etc. FIG. The flowchart which shows an electric motor control process. (A) is a graph which shows the time change of the temperature in a 1st case, (b) is a graph which shows the time change of the rotation speed in a 1st case, (c) is a high temperature stop in a 1st case The time chart which shows the ON / OFF aspect of control. (A) is a graph which shows the time change of the temperature in a 2nd case, (b) is a graph which shows the time change of the rotation speed in a 2nd case, (c) is a high temperature stop in a 2nd case The time chart which shows the ON / OFF aspect of control.

  Hereinafter, an embodiment of the electric compressor will be described. The electric compressor of this embodiment is used for a heat pump, for example. Moreover, the heat pump of this embodiment is mounted, for example in the vehicle, and is used as a car air conditioner.

  As shown in FIG. 1, the heat pump 100 includes an electric compressor 10 and an external refrigerant circuit 101 that supplies refrigerant to the electric compressor 10. The external refrigerant circuit 101 has, for example, a heat exchanger and an expansion valve. The heat pump 100 heats and cools the interior of the vehicle by compressing the refrigerant by the electric compressor 10 and performing heat exchange and expansion of the refrigerant by the external refrigerant circuit 101.

  The heat pump 100 includes an air conditioning ECU 102 that controls the entire heat pump 100. The air conditioning ECU 102 is configured to be able to grasp the in-vehicle temperature, the set temperature of the car air conditioner, and the like, and based on these parameters, various commands such as an ON / OFF command and a command for instructing the rotational speed to the electric compressor 10 are provided. Send a command.

  The electric compressor 10 includes a housing 11 in which a suction port 11 a into which a refrigerant is sucked from an external refrigerant circuit 101 is formed, and a compression unit 12 and an electric motor 13 housed in the housing 11.

  The housing 11 has a substantially cylindrical shape as a whole, and is formed of a material having heat conductivity (for example, a metal such as aluminum). The housing 11 has a discharge port 11b through which a refrigerant is discharged.

  The compression unit 12 compresses the refrigerant sucked into the housing 11 from the suction port 11a and discharges the compressed refrigerant from the discharge port 11b. In addition, the specific structure of the compression part 12 is arbitrary, such as a scroll type, a piston type, and a vane type.

  The electric motor 13 drives the compression unit 12. The electric motor 13 includes, for example, a columnar rotation shaft 21 that is rotatably supported with respect to the housing 11, a cylindrical rotor 22 that is fixed to the rotation shaft 21, and a stator 23 that is fixed to the housing 11. And have. The axial direction of the rotating shaft 21 and the axial direction of the cylindrical housing 11 coincide with each other. The stator 23 includes a cylindrical stator core 24 and a coil 25 wound around teeth formed on the stator core 24. The rotor 22 and the stator 23 face each other in the radial direction of the rotating shaft 21.

  As shown in FIG. 1, the electric compressor 10 includes an inverter unit 30 having an inverter 31 as a drive circuit for driving the electric motor 13 and a case 32 in which the inverter 31 is accommodated. The coil 25 of the electric motor 13 and the inverter 31 are connected by a connector or the like (not shown).

  The case 32 is formed of a material having heat conductivity (for example, a metal such as aluminum), and includes a plate-like base member 41 and a bottomed cylindrical cover member 42 assembled to the base member 41. Have. The base member 41 is in contact with the housing 11, specifically, with respect to the wall portion 11 c opposite to the discharge port 11 b of both wall portions in the axial direction of the housing 11. ) To the housing 11. Thereby, the case 32 in which the inverter 31 is accommodated is attached to the housing 11. That is, in the electric compressor 10 of the present embodiment, the inverter 31 is integrated.

  The inverter 31 includes, for example, a circuit board 51 fixed to the base member 41 and a power module 52 electrically connected to the circuit board 51. Various electronic components and wiring patterns are mounted on the circuit board 51, for example, a temperature sensor 53 for measuring the ambient temperature in the case 32 is mounted. A connector 54 is provided on the outer surface of the cover member 42 in the case 32, and the circuit board 51 and the connector 54 are electrically connected. Power is supplied to the inverter 31 from a DC power source as an external power source via the connector 54, and the air conditioning ECU 102 and the inverter 31 are electrically connected.

  Here, the inverter 31 is disposed at a position where it is thermally coupled to the housing 11. Specifically, the power module 52 of the inverter 31 is in contact with the base member 41. As already described, the base member 41 is in contact with the wall portion 11 c of the housing 11. For this reason, the inverter 31 (specifically, the power module 52) and the housing 11 are thermally coupled via the base member 41.

  As shown in FIG. 2, the coil 25 of the electric motor 13 has a three-phase structure including, for example, a u-phase coil 25u, a v-phase coil 25v, and a w-phase coil 25w. Each coil 25u-25w is Y-connected, for example.

  The power module 52 includes u-phase power switching elements Qu1 and Qu2 corresponding to the u-phase coil 25u, v-phase power switching elements Qv1 and Qv2 corresponding to the v-phase coil 25v, and w-phase power switching corresponding to the w-phase coil 25w. Elements Qw1 and Qw2 are provided.

  Each power switching element Qu1, Qu2, Qv1, Qv2, Qw1, Qw2 (hereinafter simply referred to as each power switching element Qu1-Qw2) is configured by, for example, an IGBT. Each power switching element Qu1-Qw2 operates normally when the temperature of each power switching element Qu1-Qw2 is equal to or higher than a predetermined operation lower limit temperature Tmin and equal to or lower than a predetermined operation upper limit temperature. That is, the operation lower limit temperature Tmin is the lower limit value of the operation guarantee range of each of the power switching elements Qu1 to Qw2, in other words, the lower limit value of the operation guarantee range of the power module 52 (inverter 31). That is, the power module 52 (inverter 31) operates normally when the temperature is not lower than the operating lower limit temperature Tmin and not higher than the operating upper limit temperature.

  The u-phase power switching elements Qu1 and Qu2 are connected to each other in series via a connection line, and the connection line is connected to the u-phase coil 25u. And direct-current power from DC power supply E is input into the serial connection body of each u phase power switching element Qu1, Qu2. The other power switching elements Qv1, Qv2, Qw1, and Qw2 are connected in the same manner as the u-phase power switching elements Qu1 and Qu2, except that the corresponding coils are different. . The inverter 31 has a smoothing capacitor C1 connected in parallel to the DC power source E.

  The power module 52 includes a control unit 55 that controls the inverter 31 (specifically, switching operations of the power switching elements Qu1 to Qw2). The control unit 55 drives, that is, rotates the electric motor 13 by periodically turning on / off each of the power switching elements Qu1 to Qw2.

  Here, the control unit 55 can control the rotational speed r of the electric motor 13 by variably controlling the ON / OFF duty ratio of each of the power switching elements Qu1 to Qw2.

  The control unit 55 is electrically connected to the air conditioning ECU 102, and when receiving a command value for the rotational speed r from the air conditioning ECU 102, except for a special situation such as when it is necessary to perform control at a low temperature. Then, the electric motor 13 is rotated at the rotation speed r corresponding to the command value.

  As shown in FIG. 2, the inverter 31 includes a current value measurement unit 61 that measures a current value I flowing through the electric motor 13 and transmits the measurement result to the control unit 55. The electric compressor 10 includes a rotation speed detector 62 that detects the rotation speed r of the electric motor 13 and transmits the detection result to the control unit 55. Thereby, the control part 55 can grasp | ascertain the electric current value I and the rotation speed r. The current value measuring unit 61 is mounted on, for example, the circuit board 51 (see FIG. 1).

The temperature sensor 53 transmits the measurement result to the control unit 55. The control unit 55 grasps the inverter temperature T that is the temperature of the inverter 31 based on the measurement result of the temperature sensor 53.
Here, the inverter temperature T is, for example, the temperature of the power module 52. In this case, the control unit 55 stores data related to the correlation between the measured temperature of the temperature sensor 53 and the temperature of the power module 52 in advance, and corresponds to the measurement result of the temperature sensor 53 by referring to the data. The temperature of the power module 52 is derived, and the temperature is set as the inverter temperature T. That is, the temperature sensor 53 is used to measure the inverter temperature T.

  The inverter temperature T is not limited to the above, and may be any temperature as long as the temperature is related to the inverter 31. For example, the measured value measured by the temperature sensor 53, that is, the ambient temperature in the case 32 may be used.

  Here, the temperature of the electric motor 13 depends on the rotational speed r and the current value I. Specifically, the temperature of the electric motor 13 increases as the current value I increases. Moreover, since the refrigerant | coolant flow rate suck | inhaled in the housing 11 becomes small, so that the rotation speed r becomes low, the temperature of the electric motor 13 becomes high.

  On the other hand, the control part 55 of this embodiment performs the high temperature stop control which stops the electric motor 13, when the relationship between the electric current value I and the rotation speed r is the relationship from which the electric motor 13 becomes high temperature. It has a function. Specifically, as shown in FIG. 3, the control unit 55 continues operation (rotation) when the intersection of the rotation speed r and the current value I is included in the operation region A1 under a predetermined condition. When the intersection of the rotation speed r and the current value I is included in the region A2 where the temperature of the electric motor 13 is higher than the operation region A1, the electric motor 13 is stopped.

  In the present embodiment, the boundary line between the operation region A1 and the region A2 is a region where at least the current value I is greater than or equal to a predetermined threshold current value Ith, and the rotation number r is equal to or less than a predetermined threshold rotation number rth. It is. The threshold rotational speed rth is a parameter that varies depending on the current value I, for example. Specifically, the threshold rotation speed rth is set to a minimum value when the current value I is the threshold current value Ith, and is set to increase as the current value I increases.

  Here, when the heat pump 100 operates under a low temperature condition (for example, an ambient temperature such as room temperature is −30 ° C. or lower and a suction refrigerant temperature is −45 ° C. or lower), the housing 11 and the base member 41 are excessively moved by the refrigerant. As a result, the inverter temperature T may be excessively lowered. For example, when the intake refrigerant temperature is lower than the operation lower limit temperature Tmin, the inverter temperature T may be lower than the operation lower limit temperature Tmin during the rotation of the electric motor 13. Then, an abnormality may occur in the power module 52.

  In particular, the inverter temperature T may become excessively low based on the rotation of the electric motor 13 being stopped. More specifically, since the power switching elements Qu1 to Qw2 are periodically turned ON / OFF while the electric motor 13 is rotating, heat related to the switching loss is generated in the power switching elements Qu1 to Qw2. . On the other hand, when the rotation of the electric motor 13 is stopped, the periodic ON / OFF of the power switching elements Qu1 to Qw2 is stopped, so that heat related to the switching loss is not generated in the power switching elements Qu1 to Qw2. For this reason, when the electric motor 13 in rotation stops, each power switching element Qu1-Qw2 may be excessively cooled by the refrigerant | coolant suck | inhaled just before the stop. Therefore, for example, when the intake refrigerant temperature is lower than the operation lower limit temperature Tmin, the inverter temperature T may be lower than the operation lower limit temperature Tmin due to the stop of the electric motor 13.

  On the other hand, the control part 55 of this embodiment performs the electric motor control process which performs both the high temperature stop control mentioned above and the control for maintaining the inverter temperature T more than the operation | movement minimum temperature Tmin. The electric motor control process will be described in detail with reference to FIG. The electric motor control process is periodically performed while the electric motor 13 is rotating. In the following description, it is assumed that the heat pump 100 is in a heating operation.

First, as shown in FIG. 4, the control unit 55 grasps the current inverter temperature T based on the measurement result of the temperature sensor 53 in step S <b> 101.
In subsequent step S102, the control unit 55 determines whether or not the inverter temperature T grasped in step S101 is higher than a predetermined prohibition temperature T1. The prohibition temperature T1 is a temperature for determining whether to prohibit the high-temperature stop control, and is, for example, 0 degrees.

  When the current inverter temperature T is higher than the prohibition temperature T1, the control unit 55 performs high-temperature stop control in steps S103 to S107. Note that the function of the control unit 55 executing the processing of Steps S103 to S107 corresponds to the “high temperature stop control unit”.

  Specifically, the control unit 55 first grasps the current value I based on the measurement result of the current value measurement unit 61 in step S103, and calculates the rotation speed r based on the detection result of the rotation number detector 62. To grasp.

  In subsequent step S104, the control unit 55 determines whether or not the current value I obtained in step S103 is equal to or greater than the threshold current value Ith. When the current value I is less than the threshold current value Ith, the control unit 55 ends the electric motor control process as it is. On the other hand, when the current value I is greater than or equal to the threshold current value Ith, the control unit 55 proceeds to step S105. A threshold rotation speed rth corresponding to the grasped current value I is derived. Specifically, the control unit 55 has data in which the current value I and the threshold rotation speed rth are associated in advance, and the threshold rotation corresponding to the current value I grasped this time by referring to the data. The number rth is derived.

  Thereafter, in step S106, the control unit 55 determines whether or not the rotation speed r obtained in step S103 is equal to or less than the threshold rotation speed rth derived in step S105. When the rotational speed r is equal to or less than the threshold rotational speed rth, the control unit 55 proceeds to step S107, stops the electric motor 13 and ends the electric motor control process, while the rotational speed r is the threshold rotational speed. If it is higher than rth, the electric motor control process is terminated without stopping the electric motor 13.

  On the other hand, when the inverter temperature T is equal to or lower than the prohibition temperature T1, the control unit 55 makes a negative determination in step S102 and proceeds to step S108 without executing the high temperature stop control in steps S103 to S107. That is, the control unit 55 performs the high temperature stop control when the inverter temperature T is higher than the prohibition temperature T1, and prohibits the high temperature stop control when the inverter temperature T is equal to or lower than the prohibition temperature T1.

  In step S108 to step S112, the control unit 55 determines whether or not to perform low temperature control for limiting the rotation speed r of the electric motor 13 based on the inverter temperature T, or whether or not to cancel low temperature control. Make a decision.

  Specifically, first, in step S108, the control unit 55 determines whether or not the low temperature control is being performed. The low temperature control is a state in which the electric motor 13 is rotating at a rotation speed r lower than a normal rotation speed r0 that is a rotation speed r that is normally set. The normal rotational speed r0 is a rotational speed r corresponding to a command value instructed from the air conditioning ECU 102 to the control unit 55, for example. The normal rotational speed r0 is set based on, for example, the in-vehicle temperature or the set temperature of the car air conditioner. The rotation of the electric motor 13 at the normal rotation speed r0 is assumed to be a normal operation.

  If the low temperature control is not being performed, the control unit 55 proceeds to step S109 and determines whether or not the inverter temperature T is equal to or lower than a predetermined threshold temperature T2. The threshold temperature T2 is a temperature lower than the forbidden temperature T1 and higher than the operation lower limit temperature Tmin.

  When the inverter temperature T is higher than the threshold temperature T2, the control unit 55 ends the electric motor control process as it is. On the other hand, when the inverter temperature T is equal to or lower than the threshold temperature T2, the control unit 55 proceeds to step S110 and rotates. Low temperature control is started to decrease r and maintain the rotation of the electric motor 13 in this state, and the process proceeds to step S113.

  Here, the control unit 55 is configured to be able to reduce the rotational speed r to a threshold rotational speed rth or less in the low temperature control. The amount of reduction (deceleration amount) of the rotational speed r in the low temperature control is arbitrary, but for example, the control unit 55 is a value that is included in the region A2 depending on the current value I, specifically, the minimum threshold rotational speed rth. A value between the value and the maximum value is set as a target value, and is lowered to the target value. When the current value I is greater than or equal to the threshold current value Ith, the control unit 55 may lower the rotation speed r below the minimum value of the threshold rotation speed rth. Note that the function of the control unit 55 executing the processing of step S109 and step S110 corresponds to a “low temperature control unit”.

  If the low temperature control is already being performed, the control unit 55 makes a positive determination in step S108 and proceeds to step S111. In step S111, the control unit 55 determines whether or not the inverter temperature T is equal to or higher than a predetermined release temperature T3. The release temperature T3 is set higher than the threshold temperature T2. In the present embodiment, the release temperature T3 is set lower than the prohibition temperature T1.

  When the inverter temperature T is equal to or higher than the release temperature T3, the control unit 55 proceeds to step S112 and releases the low temperature control. Specifically, the control unit 55 increases the rotational speed r to the normal rotational speed r0. Thereafter, the control unit 55 ends the electric motor control process.

On the other hand, when the inverter temperature T is lower than the release temperature T3, the control unit 55 makes a negative determination in step S111 and proceeds to step S113. In this case, the low temperature control is continued.
After executing the process of step S110, or when negative determination is made in step S111, the control unit 55 executes the processes of step S113 to step S115. Note that the function of the control unit 55 executing the processes of steps S113 to S115 corresponds to a “low temperature stop control unit”.

  Specifically, in step S113, the controller 55 determines whether or not the inverter temperature T is equal to or lower than a predetermined low temperature stop temperature T4. In the present embodiment, the low temperature stop temperature T4 is set higher than the operation lower limit temperature Tmin and lower than the threshold temperature T2.

  When the inverter temperature T is higher than the low temperature stop temperature T4, the control unit 55 ends the electric motor control process as it is. On the other hand, when the inverter temperature T is equal to or lower than the low temperature stop temperature T4, the control unit 55 proceeds to step S114. Deceleration at the rotation speed r is started. Specifically, the control unit 55 gradually decelerates (for example, by −140 rpm / s) from the current rotational speed r. If the current value I is equal to or greater than the threshold current value Ith, the control unit 55 decelerates the rotation speed r until the rotation speed r becomes equal to or less than the threshold rotation speed rth. Then, the control unit 55 proceeds to step S115 after the rotation speed r is sufficiently decelerated, stops the electric motor 13, and ends the electric motor control process.

  Incidentally, when performing the stop control, the control unit 55 transmits a notification to that effect to the air conditioning ECU 102. When the air conditioning ECU 102 receives the notification, the control unit 55 sends a predetermined notification unit (for example, an indicator lamp). It may be used to give a notification (alarm) to that effect.

  Next, the effect | action of this embodiment is demonstrated using FIG.5 and FIG.6. 5 and 6 are examples of time changes of the inverter temperature T and the rotation speed r under the condition where the current value I is equal to or greater than the threshold current value Ith and the suction refrigerant temperature is lower than the operation lower limit temperature Tmin. In addition, an ON / OFF mode of the high temperature stop control is shown. 5C and 6C, the state where the high temperature stop control is prohibited is set to OFF, and the state where the high temperature stop control is not prohibited is set to ON.

  First, the first case will be described with reference to FIG. As shown in FIGS. 5A and 5C, when the inverter temperature T becomes the prohibition temperature T1 at the timing t1, the high temperature stop control is prohibited (ON → OFF). Thus, even if the current value I is equal to or greater than the threshold current value Ith and the rotation speed r is equal to or less than the threshold rotation speed rth, the electric motor 13 does not stop.

  After that, as shown in FIGS. 5A and 5B, when the inverter temperature T decreases and reaches the threshold temperature T2 at the timing t2, the low temperature control is started. Specifically, it is assumed that the rotational speed r is decreased and becomes lower than the threshold rotational speed rth. In this case, since the high temperature stop control is prohibited, the rotation of the electric motor 13 is continued without stopping.

  Here, the flow rate of the refrigerant sucked into the housing 11 decreases as the rotational speed r decreases. Then, the cooling of the housing 11 is reduced. For this reason, cooling of the power module 52 thermally coupled to the housing 11 is reduced. In the first case, it is assumed that the inverter temperature T has risen as shown in FIG.

  Thereafter, as shown in FIGS. 5A and 5B, when the inverter temperature T reaches the release temperature T3 during the low temperature control at the timing t3, the low temperature control is released. Thereby, since rotation speed r rises, a refrigerant | coolant flow volume rises and the temperature adjustment capability (heating capability) of the heat pump 100 improves. On the other hand, since the power flow rate of the refrigerant increases and the power module 52 is easily cooled, the inverter temperature T decreases. Thereafter, when the inverter temperature T becomes the threshold temperature T2 again at the timing of t4, the low temperature control is started.

  From the above, the electric compressor 10 continues operation in a state where the inverter temperature T is within a predetermined range (specifically, a range slightly wider than the range from the threshold temperature T2 to the release temperature T3).

  Incidentally, the prohibition temperature T1 is higher than both the threshold temperature T2 and the release temperature T3. For this reason, high temperature stop control is prohibited at least during low temperature control. Further, since the threshold temperature T2 is set higher than the operation lower limit temperature Tmin and the low temperature stop temperature T4, the electric motor 13 is gradually decelerated in a situation where the inverter temperature T is within the predetermined range. Even when the operation stops, the inverter temperature T is unlikely to be lower than the operation lower limit temperature Tmin.

  Next, the second case will be described with reference to FIG. As shown in FIGS. 6A and 6C, the high temperature stop control is prohibited when the inverter temperature T decreases and reaches the prohibition temperature T1 at the timing of t11. Then, as shown in FIGS. 6A and 6B, at the timing of t12, the inverter temperature T becomes the threshold temperature T2, and the low temperature control is started.

  Here, depending on the intake refrigerant temperature, the limited rotation speed r, and the like, the inverter temperature T may decrease without increasing even when the low temperature control is started. In the second case, as shown in FIG. 6A, it is assumed that the inverter temperature T is lowered even when the low temperature control is started. Even in this case, the temperature decrease rate is smaller in the low temperature control than the normal operation by the amount that the refrigerant flow rate is reduced. For this reason, the time until the inverter temperature T reaches the low temperature stop temperature T4 is longer.

  Thereafter, as shown in FIG. 6A, when the inverter temperature T reaches the low temperature stop temperature T4, the electric motor 13 starts decelerating. Then, the refrigerant flow rate is further reduced. On the other hand, the switching operation of each power switching element Qu1-Qw2 is continued. For this reason, the inverter temperature T rises. And the electric motor 13 stops at the timing of t14.

  Here, if the electric motor 13 stops at the timing of t13, the inverter temperature T may be lower than the operation lower limit temperature Tmin, as shown by a two-dot chain line in FIG. On the other hand, in this embodiment, the inverter temperature T is higher at the timing t14 than the timing t13. Therefore, even if the electric motor 13 is stopped, the inverter temperature T is set to the lower operation limit. It tends to be higher than the temperature Tmin.

According to the embodiment described above in detail, the following effects are obtained.
(1) The electric compressor 10 including the housing 11 in which the compression unit 12 and the electric motor 13 are accommodated and the refrigerant is sucked, and the inverter 31 disposed at a position where the refrigerant 11 is thermally coupled to the housing 11 includes: A temperature sensor 53 used for measuring the inverter temperature T and a control unit 55 for controlling the electric motor 13 by controlling the inverter 31 are provided. The controller 55 performs high-temperature stop control for stopping the electric motor 13 when the current value I of the electric motor 13 is equal to or greater than the threshold current value Ith and the rotation speed r of the electric motor 13 is equal to or less than the threshold rotation speed rth. It has a function. Thereby, excessive heat generation of the electric motor 13 can be suppressed.

  In such a configuration, the control unit 55 limits the rotational speed r when the inverter temperature T becomes equal to or lower than a predetermined threshold temperature T2 while the electric motor 13 is rotating. Specifically, the control unit 55 performs low-temperature control in which the rotational speed r is reduced and the electric motor 13 is rotated at the reduced rotational speed r. The control unit 55 prohibits the high temperature stop control during the low temperature control. That is, the control unit 55 does not stop the electric motor 13 by the high temperature stop control when the rotation speed r of the electric motor 13 is decreased by the low temperature control.

  According to such a configuration, since the high temperature stop control is prohibited during the low temperature control, even if the rotational speed r is reduced to the threshold rotational speed rth or less in a situation where the current value I is equal to or higher than the threshold current value Ith. The electric motor 13 does not stop. Therefore, compared with the situation where the high-temperature stop control is not prohibited, the rotational speed r in the low-temperature control can be lowered, and thus the refrigerant flow rate can be more suitably reduced. Therefore, it is possible to reduce the decrease in the inverter temperature T or increase the inverter temperature T. Moreover, excessive heat generation is unlikely to occur in the electric motor 13 under a relatively low temperature condition where the inverter temperature T is equal to or lower than the threshold temperature T2. For this reason, inconvenience due to the prohibition of the high temperature stop control is unlikely to occur. Therefore, it can suppress suitably that the inverter temperature T becomes low too much.

  In particular, when the electric motor 13 stops, no heat is generated in the inverter 31. Then, for example, the inverter temperature T can be lower than the operation lower limit temperature Tmin. On the other hand, in this embodiment, the inverter temperature T may be maintained at a somewhat high temperature (for example, near the threshold temperature T2) by the low temperature control. Thereby, even if it is a case where the electric motor 13 stops, the situation where the inverter temperature T becomes lower than the operation | movement minimum temperature Tmin can be suppressed, for example. Therefore, it is possible to suitably cope with a decrease in the inverter temperature T accompanying the stop of the electric motor 13.

  (2) The electric motor 13 is configured to stop based on the inverter temperature T being equal to or lower than the low temperature stop temperature T4. As a result, the electric motor 13 can be stopped before the inverter temperature T becomes excessively low. On the other hand, when the electric motor 13 stops, for example, the comfort in the vehicle interior decreases.

  In contrast, in the present embodiment, as described above, the low temperature control is started based on the fact that the inverter temperature T becomes equal to or lower than the threshold temperature T2 set higher than the low temperature stop temperature T4. As a result, it is possible to avoid the inverter temperature T from becoming the low temperature stop temperature T4, or to increase the time until the inverter temperature T reaches the low temperature stop temperature T4. Thus, for example, comfort can be improved.

  (3) The control unit 55 prohibits the high temperature stop control when the inverter temperature T is equal to or lower than the prohibition temperature T1 higher than the threshold temperature T2. In other words, the control unit 55 does not stop the electric motor 13 by the high temperature stop control when the inverter temperature T becomes equal to or lower than the prohibition temperature T1. Specifically, when the inverter temperature T is equal to or lower than the prohibition temperature T1, the control unit 55 does not execute the processes of Step S103 to Step S107. As a result, the high temperature stop control can be prohibited at a stage before the inverter temperature T reaches the threshold temperature T2, and therefore the inconvenience that the high temperature stop control is performed due to the low temperature control being performed can be avoided.

  (4) When the inverter temperature T becomes equal to or higher than the release temperature T3 that is higher than the threshold temperature T2 in the situation where the rotational speed r of the electric motor 13 is reduced by the low temperature control, Processing for releasing the control (step S111 and step S112) is executed. Thereby, since it becomes possible to raise the rotation speed r of the electric motor 13 to normal rotation speed r0, a refrigerant | coolant flow rate can be enlarged. Therefore, the temperature adjustment capability of the heat pump 100 can be improved.

  (5) In particular, the release temperature T3 is set lower than the prohibition temperature T1 that triggers the high-temperature stop control. Thereby, the inverter temperature T becomes higher than the prohibition temperature T1 during the low temperature control, and the high temperature stop control is canceled during the low temperature control. Therefore, an unintended stop of the electric motor 13 due to the high temperature stop control being performed during the low temperature control can be avoided.

  (6) The controller 55 gradually decelerates the rotational speed r of the electric motor 13 when the inverter temperature T becomes equal to or lower than the low temperature stop temperature T4 that is lower than the threshold temperature T2 during the low temperature control. Low temperature stop control for stopping the electric motor 13 is performed. In this case, while the electric motor 13 is decelerating, the refrigerant flow rate is reduced, while the operation of the inverter 31 is continued, so the inverter temperature T becomes high. Thereby, since the electric motor 13 can be stopped after the inverter temperature T becomes higher than the low temperature stop temperature T4, it is possible to suppress the inverter temperature T from becoming lower than the operation lower limit temperature Tmin. Therefore, even when the low temperature control is performed, it is possible to cope with the case where the inverter temperature T is lowered.

  Here, for example, the low temperature stop temperature T4 may be set sufficiently higher than the operation lower limit temperature Tmin in advance so that the inverter temperature T does not become lower than the operation lower limit temperature Tmin when the electric motor 13 is stopped. However, if the low-temperature stop temperature T4 is set higher, the electric motor 13 is more likely to stop by that amount, so that inconveniences such as reduced comfort in the vehicle may occur. On the other hand, in the present embodiment, as described above, since the rotational speed r is gradually decelerated before the electric motor 13 is stopped, the inverter temperature T becomes lower than the operation lower limit temperature Tmin. The low temperature stop temperature T4 can be set low while suppressing the above. Thereby, the inconvenience can be reduced.

  In particular, the control unit 55 prohibits the high temperature stop control while the rotation speed r of the electric motor 13 is being reduced by the low temperature stop control. As a result, even if the current value I of the electric motor 13 is equal to or greater than the threshold current value Ith, the rotational speed r of the electric motor 13 can be reduced to the threshold rotational speed rth or less. Therefore, since the electric motor 13 can be stopped after the inverter temperature T is further increased, the inverter temperature T can be more suitably suppressed from becoming lower than the operation lower limit temperature Tmin.

  (7) The inverter 31 includes power switching elements Qu1 to Qw2 that operate normally when the temperature is equal to or higher than a predetermined operating lower limit temperature Tmin, and the power switching elements Qu1 to Qw2 are periodically turned on / off. By doing so, the electric motor 13 is driven. The threshold temperature T2 is set higher than the operation lower limit temperature Tmin. As a result, the inverter temperature T becomes the threshold temperature T2 before the inverter temperature T reaches the operation lower limit temperature Tmin, and the low temperature control is performed. Therefore, it can suppress that the temperature of each power switching element Qu1-Qw2 becomes lower than the operation | movement minimum temperature Tmin.

  (8) The electric compressor 10 includes a base member 41 as a heat transfer member that is thermally coupled to both the housing 11 and the inverter 31 (specifically, the power module 52). Thereby, since heat exchange is performed between the refrigerant and the inverter 31 via the housing 11 and the base member 41, the temperature of the inverter 31 using the refrigerant can be adjusted.

  In particular, the base member 41 constitutes a case 32 in which the inverter 31 is accommodated, and is used to attach the case 32 to the housing 11. In other words, since the temperature of the inverter 31 can be adjusted using the base member 41 used to attach the inverter 31 to the housing 11, the base member 41 can be multifunctional.

In addition, you may change the said embodiment as follows.
The power module 52 of the inverter 31 and the base member 41 may not be in contact with each other and may be arranged apart from each other. Even in this case, since the ambient temperature in the case 32 is adjusted by the refrigerant, the temperature of the power module 52 is adjusted accordingly.

  The base member 41 may be omitted and the cover member 42 may be fixed to the wall portion 11c of the housing 11. In this case, the inverter 31 is accommodated in a space defined by the cover member 42 and the wall portion 11 c of the housing 11. Even in such a configuration, the inverter 31 and the housing 11 are thermally coupled. In short, the inverter 31 may be disposed at a position where it is thermally coupled to the housing 11. In this case, the inverter 31 may be separated from or in contact with the base member 41 or the wall portion 11 c of the housing 11.

The threshold rotation speed rth may be a fixed value that does not vary regardless of the current value I.
O The setting mode of the amount of decrease in the rotational speed r related to low temperature control is arbitrary. For example, if the current value I is equal to or greater than the threshold current value Ith, the control unit 55 derives a threshold rotation speed rth corresponding to the current current value I, and sets the threshold rotation speed rth in advance. You may reduce to a small value by the prescribed amount. In this case, the amount of decrease differs according to the current rotational speed r.

  Further, for example, the control unit 55 may be configured to decrease the current rotation speed r by a predetermined fixed amount regardless of the current rotation speed r and the current value I. In this case, depending on the current rotational speed r and current value I and the amount of decrease, the rotational speed r can be equal to or less than the threshold rotational speed rth. That is, the control unit 55 may change the amount of decrease in accordance with the current rotational speed r, current value I, or the like, or may fix it. In any case, the rotation speed r can be equal to or less than the threshold rotation speed rth.

  The control unit 55 may be configured to perform feedback control of the rotational speed r based on a change in the inverter temperature T so that the rotational speed r is decreased until the inverter temperature T increases. Thereby, it can suppress that inverter temperature T becomes lower than threshold temperature T2 as much as possible.

The prohibited temperature T1 is not limited to 0 degrees and is arbitrary as long as the temperature is higher than the threshold temperature T2 and the high-temperature stop control is appropriately performed.
The control unit 55 may be configured to prohibit the high temperature stop control only during the low temperature control. In short, the control unit 55 may prohibit the high temperature stop control at least during the low temperature control. In other words, the prohibition period during which the high temperature stop control is prohibited may include a period during which the low temperature control is performed.

  The low temperature control release condition is not limited to the inverter temperature T being equal to or higher than the release temperature T3. For example, the fact that a predetermined time has elapsed from the start timing of the low temperature control may be set as the release condition of the low temperature control.

  The control unit 55 may immediately stop the electric motor 13 without gradually reducing the rotational speed r based on the inverter temperature T being equal to or lower than the low temperature stop temperature T4. In this case, the low temperature stop temperature T4 may be set sufficiently higher than the operation lower limit temperature Tmin so that the inverter temperature T when the electric motor 13 is stopped does not become lower than the operation lower limit temperature Tmin.

○ Steps S113 to S115 may be omitted.
The specific configuration of each of the power switching elements Qu1 to Qw2 is not limited to the IGBT, and is arbitrary, and may be a power MOSFET, for example.

  The temperature sensor 53 may measure the temperature of the base member 41. In this case, the control unit 55 may estimate the temperature of the power module 52 from the temperature of the base member 41, and use the estimated temperature as the inverter temperature T.

(Circle) heat pump 100 is not restricted to a vehicle, You may mount in another apparatus. The electric compressor 10 may be used for applications other than the heat pump 100.
The attachment position of the inverter unit 30 with respect to the housing 11 is arbitrary, and may be, for example, the outer surface of a portion of the housing 11 that faces the outer peripheral surface of the stator 23.

  The position of the control unit 55 is not limited to the power module 52 and may be arbitrary, for example, may be mounted on the circuit board 51. Moreover, the attachment position of the temperature sensor 53 is arbitrary, for example, may be in the power module 52.

  ○ When the inverter temperature T is lower than a specified temperature (for example, −20 degrees) set higher than the low temperature stop temperature T4, the control unit 55 receives a stop command for the electric motor 13 from the air conditioning ECU 102. The electric motor 13 may be stopped after the rotational speed r of the electric motor 13 is gradually reduced. In short, the controller 55 gradually reduces the rotational speed r of the electric motor 13 when a predetermined stop condition is satisfied in a situation where the inverter temperature T is lower than a predetermined specified temperature. The electric motor 13 may be stopped. The stop condition is arbitrary when the inverter temperature T becomes the low temperature stop temperature T4 or when a stop command is issued. Further, the specified temperature may be higher than the threshold temperature T2.

Next, a preferable example that can be grasped from the embodiment and another example will be described below.
(A) A heat transfer member that is used to attach the drive circuit to the housing and is thermally coupled to both the housing and the drive circuit. 5. The electric compressor according to claim 5.

  (B) a housing into which refrigerant is sucked, a compression unit that is accommodated in the housing and compresses and discharges the refrigerant, an electric motor that is accommodated in the housing and drives the compression unit, and the housing A drive circuit that is thermally coupled to drive the electric motor; a temperature measurement unit that is used to measure the temperature of the drive circuit; and a control unit that controls the electric motor by controlling the drive circuit; The controller is configured such that, during the rotation of the electric motor, the current value of the electric motor is equal to or greater than a predetermined threshold current value, and the rotational speed of the electric motor is Is set to a predetermined threshold rotational speed or less, a high-temperature stop control unit that stops the electric motor, and a temperature of the drive circuit during the rotation of the electric motor is predetermined. A low-temperature stop control unit that stops the electric motor after gradually decelerating the rotation speed of the electric motor based on being below the temperature stop temperature, and at least the low-temperature stop control unit of the electric motor The electric compressor characterized by prohibiting the stop of the electric motor by the high-temperature stop control unit during deceleration of the rotational speed.

  When attention is paid to the above configuration, the low temperature control is not an essential configuration. That is, the processing of step S108 to step S112 related to the start and release of the low temperature control may be omitted.

  DESCRIPTION OF SYMBOLS 10 ... Electric compressor, 11 ... Housing, 12 ... Compression part, 13 ... Electric motor, 31 ... Inverter (drive circuit), 41 ... Base member (heat transfer member), 52 ... Power module, 55 ... Control part, 100 ... Heat pump, I ... current value of electric motor, Ith ... threshold current value, r ... electric motor rotation speed, rth ... threshold rotation speed, T ... inverter temperature, T1 ... forbidden temperature, T2 ... threshold temperature, T3 ... release temperature, T4 ... low temperature stop temperature, Tmin ... lower limit temperature of operation.

Claims (5)

A housing into which refrigerant is sucked;
A compressing unit housed in the housing and compressing and discharging the refrigerant;
An electric motor housed in the housing and driving the compression section;
A drive circuit that is thermally coupled to the housing and drives the electric motor;
A temperature measuring unit for measuring the temperature of the drive circuit;
A control unit for controlling the electric motor by controlling the drive circuit;
An electric compressor comprising:
The controller is
During rotation of the electric motor, when the current value of the electric motor is equal to or greater than a predetermined threshold current value and the rotation speed of the electric motor is equal to or less than a predetermined threshold rotation speed, the electric motor A high temperature stop control unit for stopping the motor;
A low temperature control unit that reduces the rotational speed of the electric motor when the temperature of the drive circuit measured by the temperature measurement unit during rotation of the electric motor becomes equal to or lower than a predetermined threshold temperature;
And the electric motor is not stopped by the high temperature stop control unit when the rotational speed of the electric motor is reduced by the low temperature control unit.   2. The electric compressor according to claim 1, wherein the control unit does not stop the electric motor by the high temperature stop control unit when a temperature of the drive circuit becomes equal to or lower than a prohibition temperature that is higher than the threshold temperature.   When the temperature of the drive circuit is equal to or higher than a release temperature that is higher than the threshold temperature in a situation where the rotation speed of the electric motor is reduced by the low temperature control unit, the low temperature control unit The electric compressor according to claim 1, wherein the reduction in the rotational speed of the electric motor due to the is canceled.   When the temperature of the drive circuit is lower than the low temperature stop temperature, which is lower than the threshold temperature, in the situation where the rotation speed of the electric motor is reduced by the low temperature control unit, the control unit The electric compressor as described in any one of Claims 1-3 provided with the low temperature stop control part which stops the said electric motor, after gradually decelerating the rotation speed of. The drive circuit has a switching element that operates normally when the temperature is equal to or higher than a predetermined operation lower limit temperature, and drives the electric motor when the switching element is periodically turned ON / OFF.
The electric compressor according to any one of claims 1 to 4, wherein the threshold temperature is set to be higher than the operation lower limit temperature.