Control method for heat pump system, control device for heat pump system, and heat pump circuit

Abstract

To provide a control method for a heat pump system, a control device for a heat pump system, and a heat pump circuit that can more quickly heat a heating object such as a battery in comparison to a conventional technique when performing d-axis electric conduction in the heat pump system that uses an electric powertrain as a heat source.SOLUTION: A control method for a heat pump system generates heat by an electric powertrain through d-axis electric conduction that increases the d-axis current of a rotary electric machine 21 when heating a target object 10, acquires the rotary electric machine temperature T2 being the temperature of the rotary electric machine 21, acquires the refrigerant temperature T1 being the temperature of the refrigerant circulating in a cooling circuit 11, separates the rotary electric machine 21 from the cooling circuit 11 when the rotary electric machine temperature T2 is lower than the refrigerant temperature T1, and increases the refrigerant temperature T1 by using the heat generated in an inverter 22 out of the rotary electric machine 21 and the inverter 22 through the d-axis electric conduction.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a control method for a heat pump system, a control device for a heat pump system, and a heat pump circuit. [Background technology]

[0002] Patent Document 1 relates to vehicle heating using a heat pump circuit that uses the outside air of the vehicle as the main heat source, and discloses that when the outside air is below -10°C, the heat source is cooling water for cooling a storage battery, which is heated by an electric hot water heater, and this heated cooling water is used as the heat source for the heat pump circuit. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7053906 Summary of the Invention [Problem to be solved by the invention]

[0004] In an electric vehicle, a battery, a heater core, etc. may be heated by a heat pump system that uses the electric powertrain as a heat source. In addition, in an electric vehicle, in order to quickly reach a target temperature for the battery, etc., more heat may be actively generated in the electric powertrain by energization control (so-called d-axis energization) that increases the d-axis current of a rotating electric machine included in the electric powertrain.

[0005] However, since the heat capacity of the rotating electric machine in the electric powertrain is considerably large, when the temperature of the rotating electric machine is low, the heat generated in the electric powertrain is likely to be absorbed by the rotating electric machine, and therefore, even if the d-axis current is applied, it may still take a long time to heat the heating target such as the battery.

[0006] The present invention aims to provide a control method for a heat pump system, a control device for a heat pump system, and a heat pump circuit that can heat an object to be heated, such as a battery, more quickly than conventional methods when d-axis current is applied in a heat pump system that uses an electric powertrain as a heat source. [Means for solving the problem]

[0007] One aspect of the present invention is a control method for a heat pump system including an electric powertrain including a rotating electric machine and an inverter driving the rotating electric machine, a cooling circuit for cooling the electric powertrain, and a heat transport circuit thermally connected to the cooling circuit and transporting heat generated in the electric powertrain to a target to be heated using a compressor, the control method for the heat pump system being configured to generate heat in the electric powertrain by d-axis current supply that increases a d-axis current of the rotating electric machine when heating the target to be heated. In the control method for the heat pump system, a rotating electric machine temperature, which is the temperature of the rotating electric machine, is obtained, a refrigerant temperature, which is the temperature of the refrigerant circulating in the cooling circuit, is obtained, and when the rotating electric machine temperature is lower than the refrigerant temperature, the rotating electric machine is separated from the cooling circuit. Then, the d-axis current supply is used to increase the refrigerant temperature using heat generated in the inverter of the rotating electric machine and the inverter. Effect of the Invention

[0008] According to the present invention, it is possible to provide a control method for a heat pump system, a control device for a heat pump system, and a heat pump circuit that can heat an object to be heated, such as a battery, more quickly than conventional methods when d-axis current is applied in a heat pump system that uses an electric powertrain as a heat source. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a heat pump system. [Diagram 2] FIG. 2 is a block diagram showing the cooling circuit in the first mode. [Diagram 3]FIG. 3 is a block diagram showing the cooling circuit in the second mode. [Figure 4] FIG. 4 is a block diagram showing the cooling circuit in the third mode. [Diagram 5] FIG. 5 is a block diagram showing the cooling circuit in the fourth mode. [Figure 6] FIG. 6 is a flow chart showing the start-up of the heat pump system in a very low temperature environment. [Figure 7] FIG. 7 is a graph showing the time required to start up the heat pump system when the rotating electrical machine temperature is lower than the refrigerant temperature in an extremely low temperature environment. [Figure 8] FIG. 8 is a flowchart showing a process from start-up of the heat pump system until the temperature of the object to be heated reaches the target temperature of the object to be heated. [Figure 9] FIG. 9 is a flowchart showing mode switching of the heat pump system while the vehicle is traveling. [Figure 10] FIG. 10 is a graph showing changes in refrigerant temperature in the third and fourth modes. [Figure 11] FIG. 11 is a flowchart of the first modified example. [Figure 12] FIG. 12 is a flowchart of the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] [Embodiment] 1 is a block diagram showing a schematic configuration of a heat pump system 100. The heat pump system 100 is provided in an electric vehicle (not shown) and heats a predetermined heating target 10, for example, by heat generated in an electric powertrain (ePT). In this embodiment, the electric powertrain is the heat source (heat sink) in the heat pump system 100. The heating target 10 of the heat pump system 100 is a battery that supplies power to the electric powertrain, a heater core that is a heat source for heating, and / or other parts that require temperature adjustment. In this embodiment, the heating target 10 is a battery.

[0012] As shown in FIG. 1, the heat pump system 100 includes a heat pump circuit 101, which is a circuit that transports heat generated in an electric power train to a target to be heated 10 by refrigerant circulation and heat exchange, and a controller 102 that controls the operation of the heat pump circuit 101.

[0013] The heat pump circuit 101 includes a cooling circuit 11 and a heat transport circuit 12. The heat transport circuit 12 is composed of a first heat transport circuit 13 and a second heat transport circuit 14, for example.

[0014] The cooling circuit 11 is a circuit that cools the electric powertrain by circulating water or other liquid (hereinafter simply referred to as refrigerant) through parts of the electric powertrain that generate heat. The cooling circuit 11 can use water or any other refrigerant. In this embodiment, the refrigerant circulating through the cooling circuit 11 is water (cooling water).

[0015] In this embodiment, for simplicity, the electric power train is assumed to be composed of a rotating electric machine 21 and an inverter 22. Both the rotating electric machine 21 and the inverter 22 are heat generating parts of the electric power train. The rotating electric machine 21 and the inverter 22 each function as a heat source in the heat pump system 100. Hereinafter, when there is no need to particularly distinguish between the rotating electric machine 21, the inverter 22, and the entirety of these as heat sources of the heat pump system 100, these will be collectively referred to as the electric power train.

[0016] The rotating electric machine 21 is an electric motor that drives an electric vehicle, or a generator that generates power required for charging a battery and driving an electric vehicle. In this embodiment, the rotating electric machine 21 is an electric motor that drives an electric vehicle. The inverter 22 converts DC power output by a battery into AC power and inputs the AC power to the rotating electric machine 21, thereby driving the rotating electric machine 21. When the rotating electric machine 21 is a generator, or when the rotating electric machine 21 functions as a generator, the inverter 22 functions as a converter that converts AC power output by the rotating electric machine 21 into DC power and supplies the DC power to the battery.

[0017] The cooling circuit 11 includes a rotating electrical machine 21 and an inverter 22, which are objects to be cooled, as well as a chiller 23, an external heat exchanger 24, and a first pump 25 in a flow path of the refrigerant.

[0018] The chiller 23 cools the refrigerant, whose temperature has increased by flowing through the electric powertrain, by the working fluid (refrigerant gas) circulating through the first heat transport circuit 13. That is, the chiller 23 is a heat exchanger that exchanges heat between the refrigerant in the cooling circuit 11 and the working fluid in the first heat transport circuit 13. In other words, in the cooling circuit 11, heat recovered by the refrigerant from the electric powertrain is transferred (conducted) to the working fluid in the first heat transport circuit 13 via the chiller 23. Therefore, in the heat pump system 100, the cooling circuit 11 is a component for recovering heat from a heat source, and can also be called a heat source circuit, a heat absorption circuit, or the like.

[0019] The external heat exchanger 24 is a heat exchanger that exchanges heat between the refrigerant in the cooling circuit 11 and outside air, etc. The external heat exchanger 24 cools the refrigerant, whose temperature has increased by circulating through the cooling circuit 11, by outside air, etc. Specifically, the external heat exchanger 24 is, for example, a radiator of an electric vehicle.

[0020] The first pump 25 circulates the refrigerant in the cooling circuit 11. In this embodiment, the inverter 22 and the rotating electric machine 21 are arranged in series in this order along the flow direction of the refrigerant, and the first pump 25 is arranged upstream of the inverter 22. Therefore, the first pump 25 circulates the refrigerant in the following order: the inverter 22, the rotating electric machine 21, the chiller 23, and the external heat exchanger 24. Note that the cooling circuit 11 may be configured such that the rotating electric machine 21 and the inverter 22 are arranged in parallel with respect to the flow of the refrigerant.

[0021] In addition to the above, the cooling circuit 11 includes a bypass 26 and a valve 27, and a bypass 28 and a valve 29.

[0022] The bypass 26 and the valve 27 are components for isolating the external heat exchanger 24 from the cooling circuit 11 as necessary. The bypass 26 is a flow path that connects a refrigerant inlet and outlet of the external heat exchanger 24 and circulates the refrigerant by bypassing the external heat exchanger 24. The valve 27 is provided, for example, at the upstream end of the bypass 26, and switches the destination of the refrigerant that has circulated through the chiller 23 to either the external heat exchanger 24 or the bypass 26. In other words, the valve 27 separates the external heat exchanger 24 from the cooling circuit 11 by causing the refrigerant to flow through the bypass 26. The switching of the refrigerant flow path by the valve 27 is appropriately controlled by the controller 102.

[0023] The bypass 28 and the valve 29 are components for isolating the rotating electric machine 21 from the cooling circuit 11 as necessary. The bypass 28 is a flow path that connects a refrigerant inlet and outlet for the rotating electric machine 21 and circulates the refrigerant by bypassing the rotating electric machine 21. The valve 29 is provided, for example, at the upstream end of the bypass 28, and switches the destination of the refrigerant that has circulated through the inverter 22 to either the rotating electric machine 21 or the bypass 28. In other words, the valve 29 separates the rotating electric machine 21 from the cooling circuit 11 by causing the refrigerant to flow through the bypass 28. The switching of the refrigerant flow path by the valve 29 is appropriately controlled by the controller 102.

[0024] The heat pump system 100 has four operating modes according to the switching of the flow paths by the valves 27 and 29. Each of these modes will be described in detail later.

[0025] Furthermore, the valves 27 and 29 can not only simply switch the flow path of the refrigerant, but also adjust the flow rate of the refrigerant. For example, the valve 29 can selectively switch the flow path of the refrigerant to either the rotating electric machine 21 or the bypass 28, and can also reduce the flow rate of the refrigerant flowing through the bypass 28 as necessary. Such adjustment of the flow rate of the refrigerant is controlled by the controller 102.

[0026] In this embodiment, the cooling circuit 11 further includes a temperature sensor 30 and a temperature sensor 31 .

[0027] The temperature sensor 30 measures the temperature of the refrigerant flowing through the cooling circuit 11 (hereinafter referred to as refrigerant temperature T1). In particular, the temperature sensor 30 measures the temperature of the refrigerant warmed by flowing through the electric powertrain. Therefore, in this embodiment, the temperature sensor 30 measures the refrigerant temperature T1 upstream of the chiller 23 after the outlet of the rotating electric machine 21 and the bypass 28 join together. The controller 102 can acquire the refrigerant temperature T1 as needed.

[0028] The temperature sensor 31 measures the temperature of the rotating electric machine 21 (hereinafter referred to as the rotating electric machine temperature T2). The rotating electric machine temperature T2 represents the temperature of a part or the entire rotating electric machine 21. The controller 102 can acquire the rotating electric machine temperature T2 as needed.

[0029] The heat transport circuit 12 is thermally connected to the cooling circuit 11, and transports heat recovered from a heat source in the cooling circuit 11 to the target 10 to be heated. In this embodiment, as described above, the heat transport circuit 12 is composed of a first heat transport circuit 13 and a second heat transport circuit 14.

[0030] The first heat transport circuit 13 is a circuit that transfers heat in a specific direction by repeatedly evaporating and liquefying a working fluid (so-called refrigerant gas). Specifically, the first heat transport circuit 13 is composed of a chiller 23, a compressor 33, a water-cooled condenser (WCDS), a receiver 35, and an expansion valve 36, and circulates the working fluid in this order. In this way, the first heat transport circuit 13 transfers heat from the chiller 23 to the water-cooled condenser 34.

[0031] The working fluid circulating in the first heat transport circuit 13 exchanges heat with the refrigerant in the cooling circuit 11 in the chiller 23. That is, the working fluid in the first heat transport circuit 13 is warmed by heat generated in the electric powertrain and vaporized (evaporates) in the chiller 23. Therefore, in the first heat transport circuit 13, the chiller 23 is an evaporator or vaporizer of the working fluid.

[0032] The compressor 33 compresses the working fluid that flows in via the chiller 23, and sends the working fluid, which has thus become high temperature and high pressure, to the water-cooled condenser 34.

[0033] The compressor 33 is premised on compressing the working fluid in a gaseous state. Therefore, if a working fluid in a liquid state (substantially incompressible) flows into the compressor 33 and so-called liquid compression occurs, problems such as damage to the compressor 33 may occur. Therefore, an accumulator (liquid separator) may be provided at the inlet of the working fluid to the compressor 33.

[0034] However, in order to reduce the pressure loss of the working fluid and increase the heat transport efficiency, the accumulator is often omitted in the heat pump system mounted on the electric vehicle. For this reason, the compressor 33 (first heat transport circuit 13) of the heat pump system 100 of this embodiment also does not have an accumulator. On the other hand, regardless of the accumulator, in order to reliably vaporize the working fluid flowing into the compressor 33 and prevent liquid compression from occurring, the heat pump system 100 manages the state of the working fluid flowing into the compressor 33.

[0035] In particular, the heat pump system 100 of this embodiment uses the refrigerant temperature T1 of the cooling circuit 11 to manage the state of the working fluid to be flowed into the compressor 33. Specifically, in the heat pump system 100, a threshold value (hereinafter, referred to as a first temperature TH1) is set for the refrigerant temperature T1 of the cooling circuit 11, and the compressor 33 can be started only when the refrigerant temperature T1 is equal to or higher than the first temperature TH1. This first temperature TH1 determines whether or not the compressor 33 can be started locally, but in reality, it determines whether or not the entire heat pump system 100 can be started (whether or not the heat pump can be started). The first temperature TH1 is determined in advance by an experiment, a simulation, or the like. The first temperature TH1 is, for example, about 0°C.

[0036] The water-cooled condenser 34 exchanges heat between the high-temperature, high-pressure working fluid flowing in from the compressor 33 and the heat medium (water) flowing through the second heat transport circuit 14. As a result, the working fluid loses heat to the heat medium in the second heat transport circuit 14 and becomes low-temperature, high-pressure. As a result, all or part of the working fluid is condensed (liquefied). Meanwhile, the temperature of the heat medium flowing through the second heat transport circuit 14 increases due to the heat exchange in the water-cooled condenser 34. As described above, the heat of the working fluid is recovered from the heat generated in the electric powertrain, so the heat generated in the electric powertrain moves to the second heat transport circuit 14 via the water-cooled condenser 34. Therefore, in the first heat transport circuit 13, the water-cooled condenser 34 is a heat exchanger and a condenser of the working fluid.

[0037] In this embodiment, as described above, the first heat transport circuit 13 uses the water-cooled condenser 34 to transfer the heat generated in the electric powertrain to the target to be heated 10, but the present invention is not limited to this, and the first heat transport circuit 13 can transfer the heat generated in the electric powertrain to the target to be heated 10 using a heat exchanger other than the water-cooled condenser 34. For example, the first heat transport circuit 13 can be provided with a so-called inner condenser (air-cooled condenser) instead of the water-cooled condenser 34.

[0038] In this case, the air-cooled condenser itself is used as a heater core, so that the heat pump system 100 can heat the vehicle interior. However, since the water-cooled condenser 34 usually has higher heat exchange efficiency than the air-cooled condenser, when the condenser of the first heat transport circuit 13 is the water-cooled condenser 34, the transport efficiency of the heat generated in the electric powertrain is improved. On the other hand, since the compressor 33 does not have an accumulator, when the condenser of the first heat transport circuit 13 is the water-cooled condenser 34, liquid compression is likely to occur.

[0039] The receiver 35 temporarily stores the working fluid that has become low temperature and high pressure by condensation in the water-cooled condenser 34. At this time, the receiver 35 separates the working fluid in a gas state from the working fluid in a liquid state. Then, the receiver 35 sends the working fluid in a liquid state to the expansion valve 36. The receiver 35 is also called a receiver tank or a liquid tank.

[0040] The expansion valve 36 expands the working fluid and sends the low-temperature, low-pressure working fluid to the chiller 23. The expansion valve 36 is, for example, a thermostatic expansion valve (TXV) or an electronic expansion valve (EXV).

[0041] The second heat transport circuit 14 is composed of a water-cooled condenser 34, the object to be heated 10, and a second pump 37. The second pump 37 circulates water, which is a heat medium (refrigerant), between the water-cooled condenser 34 and the object to be heated 10. As a result, the object to be heated 10 is heated by heat generated in the electric powertrain.

[0042] In addition, in the present embodiment, the second heat transport circuit 14 includes a temperature sensor 38. The temperature sensor 38 measures the temperature of the object to be heated 10 (hereinafter referred to as the temperature of the object to be heated T3). The controller 102 can appropriately acquire the temperature of the object to be heated T3.

[0043] The controller 102 is a control device that comprehensively controls the heat pump system 100. Specifically, the controller 102 controls the operation of the heat pump circuit 101 configured as described above. The controller 102 is composed of, for example, one or more computers and is programmed to operate the heat pump system 100 in various modes described later. The controller 102 may be integrally configured with the controller (control device) that controls the heat pump system 100.

[0044] In the present embodiment, the controller 102 particularly performs control related to d-axis energization, setting of the target refrigerant temperature T1 * and switching of the flow path of the cooling circuit 11 (mode switching of the heat pump system 100).

[0045] <d-axis energization> When it is necessary to warm the object to be heated 10, the controller 102 can actively generate heat in the electric power train by so-called d-axis energization. D-axis energization is an energization control that selectively increases the d-axis current among the d-axis current and q-axis current of the rotating electrical machine 21. D-axis energization increases the power consumption of the electric power train without changing the rotation state and output torque of the rotating electrical machine 21, and as a result, increases the heat generated in the electric power train. "Increasing" the d-axis current means increasing the d-axis current already flowing through the rotating electrical machine 21 or flowing a d-axis current that is not flowing. When d-axis energization is performed, heat due to, for example, copper loss and iron loss increases in the rotating electrical machine 21, and heat due to, for example, conduction loss of the switching element increases in the inverter 22.

[0046] In this embodiment, a scene will be described in particular in which heat generated in an electric power train by d-axis current is transported by the heat pump system 100 to heat the heating target 10. A typical example is a scene in which it is necessary to warm up the battery or heat the vehicle interior when using an electric vehicle that has been parked in a low-temperature environment. Another typical example is a scene in which it is necessary to use the heat pump system 100 to increase the temperature of the battery before the electric vehicle arrives at a charging spot in order to improve (optimize) the charging efficiency of rapid charging.

[0047] In addition, when the d-axis current is applied, the controller 102 controls the carrier frequency f c For example, when performing d-axis current supply while the rotating electric machine 21 is stopped, the controller 102 may drive the inverter 22 at a carrier frequency f2 that is higher than the carrier frequency f1 used to drive the rotating electric machine 21.

[0048] <Target refrigerant temperature T1 * Settings > The controller 102 sets a target (hereinafter, referred to as target coolant temperature T1 * In particular, when heat is generated in the electric power train by energizing the d-axis and the heating target 10 is heated by the heat, the refrigerant temperature T1 is set to the target refrigerant temperature T1 in the shortest possible time. * The amount of current to be increased by the d-axis current supply and the flow path of the cooling circuit 11 are adjusted so as to reach the above.

[0049] For example, when the target 10 needs to be heated by the heat pump system 100, the refrigerant temperature T1 is lower than the temperature at which the compressor 33 can be started without causing liquid compression (i.e., the first temperature TH1). * is set to the first temperature TH1.

[0050] In addition, when the heat pump system 100 can transport the heat required for the heating target 10 at any time, such as when the electric vehicle is running, the target refrigerant temperature T1 is set to T10 ... * is set to a predetermined temperature range determined by experiments, simulations, or the like. The controller 102 controls (limits) the operation of the electric power train and each part of the heat pump system 100 so that the refrigerant temperature T1 falls within this temperature range. In this embodiment, for simplicity, the target refrigerant temperature T1 is set to * is set to a specific temperature (hereinafter referred to as second temperature TH2) higher than the first temperature TH1.

[0051] However, when it becomes necessary to warm the battery in preparation for rapid charging, etc., or when high-output heating is required, the target refrigerant temperature T1 * is set to a temperature (hereinafter referred to as third temperature TH3) that exceeds the above temperature range (second temperature TH2). This third temperature TH3 is set as appropriate according to the state of the electric vehicle (such as the temperature and remaining charge of the battery) and the demands made on the electric vehicle (demand for heating output and demand for increased output). In other words, the third temperature TH3 is a variable value that is set or changed (adjusted) as appropriate according to the specific circumstances relating to the running of the electric vehicle, etc. Therefore, the third temperature TH3 may change with the passage of time and the associated changes in the specific circumstances.

[0052] In this embodiment, for example, the controller 102 appropriately sets a target temperature for the heating target temperature T3 (hereinafter, the target heating target temperature T3 * Then, the controller 102 determines whether the heating target temperature T3 is equal to or lower than the target heating target temperature T3 * The third temperature TH3 is set to reach

[0053] For example, when a battery with a low remaining capacity needs to be charged, the battery temperature for efficient charging (fast charging) is set to a target heating target temperature T3 *Therefore, the controller 102 determines whether the battery reaches the target heating temperature T3 by the time the battery arrives at the charging spot, depending on the temperature of the battery and the distance to the charging spot. * The third temperature TH3 is set or changed so that the third temperature TH3 reaches a temperature suitable for charging.

[0054] In addition, when a passenger of the electric vehicle requests heating, the heater core temperature to meet the heating request is set to the target heating target temperature T3 * Therefore, the controller 102 controls the heater core to reach the target heating temperature T3 as quickly as possible. * The third temperature TH3 is set or changed so that:

[0055] <Switching of flow path of cooling circuit 11> The controller 102 switches the flow paths of the cooling circuit 11 based on the refrigerant temperature T1 and the rotating electric machine temperature T2. In this way, the controller 102 switches the operation state, i.e., the mode, of the heat pump system 100. There are four operation modes of the heat pump system 100, namely, a first mode M1, a second mode M2, a third mode M3, and a fourth mode M4, depending on the state of the flow paths of the cooling circuit 11.

[0056] Fig. 2 is a block diagram showing the cooling circuit 11 in the first mode M1. As shown in Fig. 2, the first mode M1 is a mode in which the refrigerant is circulated through the rotating electric machine 21, and the external heat exchanger 24 is separated from the cooling circuit 11 and the refrigerant is circulated through the bypass 26. That is, the first mode M1 is a mode in which the external heat exchanger 24 is separated from the cooling circuit 11 and the refrigerant is circulated through the rotating electric machine 21 and the inverter 22. Therefore, in the first mode M1, when d-axis current is applied, both the heat generated in the rotating electric machine 21 and the heat generated in the inverter 22 are transported to the target 10 to be heated.

[0057] The first mode M1 is selected when the electric powertrain is in a low-temperature state where cooling is not required, and heat is generated in the electric powertrain by d-axis current application, and the generated heat is used to heat the heating target 10. In this embodiment, the first mode M1 is selected when the electric powertrain is in a low-temperature state and the rotating electric machine temperature T2 is equal to or higher than the coolant temperature T1 after the start of d-axis current application.

[0058] Fig. 3 is a block diagram showing the cooling circuit 11 in the second mode M2. As shown in Fig. 3, the second mode M2 ​​is a mode in which the rotating electric machine 21 is separated from the cooling circuit 11 and the refrigerant is circulated through the bypass 28, and the external heat exchanger 24 is separated from the cooling circuit 11 and the refrigerant is circulated through the bypass 26. That is, the second mode M2 ​​is a mode in which the external heat exchanger 24 and the rotating electric machine 21 are separated from the cooling circuit and the refrigerant is circulated through the inverter 22. Therefore, in the second mode M2, when d-axis current is applied, the heat generated in the rotating electric machine 21 remains in the rotating electric machine 21, and only the heat generated in the inverter 22 is transported to the target 10 to be heated.

[0059] The second mode M2 ​​is selected when the electric powertrain is in a low-temperature state (extremely low-temperature state) such that the compressor 33 cannot be started, and heat is generated in the electric powertrain by d-axis current application, and the target 10 to be heated is heated by the heat. In this embodiment, the second mode M2 ​​is selected when the electric powertrain is in an extremely low-temperature state and the rotating electric machine temperature T2 is lower than the refrigerant temperature T1 after the start of d-axis current application.

[0060] In addition, when the second mode M2 ​​is selected, the controller 102 may disconnect the rotating electric machine 21 and the external heat exchanger 24 from the cooling circuit 11, and then reduce the opening of the valve 29 (or the valve 27) to reduce the flow rate of the refrigerant flowing through the cooling circuit 11.

[0061] FIG. 4 is a block diagram showing the cooling circuit 11 in the third mode M3. As shown in FIG. 4, the third mode M3 is a mode in which the refrigerant is circulated through the rotating electric machine 21 and the external heat exchanger 24. That is, the third mode M3 is a mode in which the refrigerant is circulated through the inverter 22, the rotating electric machine 21, and the external heat exchanger 24 without isolating either the external heat exchanger 24 or the rotating electric machine 21 from the cooling circuit 11. Therefore, in the third mode M3, when d-axis current is applied, both the heat generated in the rotating electric machine 21 and the heat generated in the inverter 22 are transported to the heating target 10. However, a part of the heat generated in the rotating electric machine 21 and the heat generated in the inverter 22 flows out to the outside air via the external heat exchanger 24.

[0062] The third mode M3 is selected when the electric powertrain has heat and needs to be cooled, such as when the electric vehicle is running. When the third mode M3 is selected, the heat pump system 100 can, in principle, heat the heating target 10 at any time. However, when the heating target temperature T3 is equal to or lower than the target heating target temperature T3 * It may take some time until the mode M3 becomes the same as the mode M1. In this embodiment, when the electric vehicle is traveling, the third mode M3 is selected in principle. When heat transport by d-axis current is required while the electric vehicle is traveling, the third mode M3 is selected (continued) if the rotating electric machine temperature T2 is equal to or higher than the coolant temperature T1.

[0063] 5 is a block diagram showing the cooling circuit 11 in the fourth mode M4. As shown in FIG. 5, the fourth mode M4 is a mode in which the rotating electric machine 21 is separated from the cooling circuit 11, the refrigerant is circulated through the bypass 28, and the refrigerant is circulated through the external heat exchanger 24. That is, the fourth mode M4 is a mode in which the rotating electric machine 21 is separated from the cooling circuit 11, and the refrigerant is circulated through the inverter 22 and the external heat exchanger 24. Therefore, in the fourth mode M4, when d-axis current is applied, the heat generated in the rotating electric machine 21 remains in the rotating electric machine 21, and only the heat generated in the inverter 22 is transported to the target 10 to be heated. However, a part of the heat generated in the inverter 22 flows out to the outside air via the external heat exchanger 24.

[0064] In the fourth mode M4, when the electric powertrain is hot and needs to be cooled, such as when the electric vehicle is running, the target heating target temperature T3 * In this embodiment, when heat transport by d-axis current supply is required while the electric vehicle is traveling, if the rotating electric machine temperature T2 is lower than the coolant temperature T1, the fourth mode M4 is selected.

[0065] However, the fourth mode M4 is not selected when there is a risk that the rotating electric machine temperature T2 will exceed the heat-resistant limit temperature of the rotating electric machine 21. In this embodiment, the controller 102 sets a heat-resistant threshold value TH OH is set in advance, and when the fourth mode M4 is to be selected, the rotating electrical machine temperature T2 is set to the heat resistance threshold value TH OH Then, the controller 102 compares the rotating electrical machine temperature T2 with the heat resistance threshold TH OH If the rotating electrical machine temperature T2 is less than the heat resistance threshold TH OH If it is equal to or greater than this, the third mode M3 is continued. OH is determined in advance by experiment, simulation, or the like so that the rotating electrical machine temperature T2 does not immediately exceed the heat-resistant limit temperature even when, for example, the accelerator is suddenly fully opened and a high torque is required.

[0066] In addition, when the fourth mode M4 is selected, the controller 102 may disconnect the rotating electric machine 21 from the cooling circuit 11 and reduce the opening of the valve 29 (or the valve 27) to reduce the flow rate of the refrigerant flowing through the cooling circuit 11.

[0067] The operation of the heat pump system 100 configured as described above will be described below. As an example, a scene will be described in which the heat pump system 100 is started from an extremely low temperature state, and then the battery is heated in preparation for rapid charging while the electric vehicle is running.

[0068] FIG. 6 is a flowchart for starting the heat pump system 100 in an extremely low temperature environment. Here, a case will be described where the battery is rapidly charged when the refrigerant temperature T1 is lower than the first temperature TH1, such as when the electric vehicle has been parked in an extremely low temperature environment for a long time. If such a battery that has been placed in an extremely low temperature environment is rapidly charged, there is a risk that electrodeposition will occur at the negative electrode of the battery, causing a short circuit with the positive electrode. Therefore, when rapidly charging the battery in an extremely low temperature environment, it is necessary to start the heat pump system 100 and warm up the battery.

[0069] On the other hand, in an extremely low temperature environment, the electric power train and the refrigerant in the cooling circuit 11, which are the heat sources of the heat pump system 100, are also cold, so that liquid compression may occur in the compressor 33 when the heat pump system 100 is started. For this reason, when the heat pump system 100 is to be used in an extremely low temperature environment, it is first necessary to sufficiently warm the refrigerant in the cooling circuit 11 by energizing the d-axis, and then start the compressor 33 (heat pump system 100). Therefore, it usually takes a long time for the heat pump system 100 to start transporting heat in an extremely low temperature environment and for the battery, which is the heating target 10, to start warming up. Therefore, in the heat pump system 100 of this embodiment, the heat pump system 100 is started quickly as follows.

[0070] Specifically, as shown in FIG. 6, when starting the heat pump system 100 in an extremely low temperature environment, the controller 102 sets the target refrigerant temperature T1 in step S10. * is set to the first temperature TH1. Then, the controller 102 starts the d-axis current supply in step S11, and starts the first pump 25 in step S12.

[0071] Furthermore, in step S13, the controller 102 acquires the rotating electrical machine temperature T2 and the coolant temperature T1, and compares them.

[0072] In step S13, when the rotating electrical machine temperature T2 is equal to or higher than the refrigerant temperature T1 (T2≧T1), the process proceeds to step S14, and the controller 102 sets the heat pump system 100 to the first mode M1 by switching the flow path. That is, the controller 102 switches the flow path of the cooling circuit 11 so that the refrigerant circulates through both the inverter 22 and the rotating electrical machine 21.

[0073] On the other hand, in step S13, when the rotating electrical machine temperature T2 is lower than the refrigerant temperature T1 (T2<T1), the process proceeds to step S15, and the controller 102 sets the heat pump system 100 (cooling circuit 11) to the second mode M2. That is, the controller 102 disconnects the rotating electrical machine 21 from the cooling circuit 11 and switches the flow path of the cooling circuit 11 so that the refrigerant circulates through the inverter 22.

[0074] Thereby, when the rotating electrical machine temperature T2 is equal to or higher than the refrigerant temperature T1 and the first mode M1 is selected, the refrigerant in the cooling circuit 11 is heated by the heat generated in the inverter 22 and the rotating electrical machine 21 by d-axis energization. Also, when the rotating electrical machine temperature T2 is lower than the refrigerant temperature T1 and the second mode M2 is selected, the refrigerant is heated by the heat generated in the inverter 22 by d-axis energization.

[0075] Thereafter, when the controller 102 confirms in step S16 that the refrigerant temperature T1 has become equal to or higher than the first temperature TH1, the controller 102 starts the compressor 33 in step S17 and starts the second pump 37 in step S18. Thereby, the heat pump system 100 starts, and the battery, which is the object to be heated 10, is heated by the heat generated by d-axis energization. When the refrigerant temperature T1 is lower than the first temperature TH1 in step S16, the process returns to step S13, and the controller 102 appropriately switches between the first mode M1 and the second mode M2 according to the magnitude relationship between the rotating electrical machine temperature T2 and the refrigerant temperature T1.

[0076] FIG. 7 is a graph showing the time required for starting the heat pump system 100 when the rotating electrical machine temperature T2 is lower than the refrigerant temperature T1 in an extremely low temperature environment. When the rotating electrical machine temperature T2 is lower than the refrigerant temperature T1, as shown in FIG. 7, the time t2 until the refrigerant temperature T1 reaches the first temperature TH1 (target refrigerant temperature T1 * ) in the second mode M2 is shorter than the time t1 until the refrigerant temperature T1 reaches the first temperature TH1 in the first mode M1 (t2 < t1). That is, when the rotating electrical machine temperature T2 is lower than the refrigerant temperature T1 in an extremely low temperature environment, it is possible to start the heat pump system 100 (compressor 33) more quickly by selecting the second mode M2 rather than setting it to the first mode M1.

[0077] When the rotating electrical machine 21 having a large heat capacity and being difficult to warm up is connected to the cooling circuit 11, the heat generated in the electric power train by d-axis energization is taken away by the rotating electrical machine 21 until the rotating electrical machine temperature T2 becomes equal to or higher than the refrigerant temperature T1. On the other hand, if the refrigerant is circulated only through the inverter 22 having a small heat capacity (volume) and being easy to warm up among the electric power train, the heat generated in the inverter 22 by d-axis energization contributes to the rise in the refrigerant temperature T1 substantially immediately after the start of d-axis energization. Therefore, the heat pump system 100 of the present embodiment can start the compressor 33 quickly by setting it to the second mode M2 when the rotating electrical machine temperature T2 is lower than the refrigerant temperature T1.

[0078] Further, in the present embodiment, when the rotating electrical machine temperature T2 becomes equal to or higher than the refrigerant temperature T1 and the heat generated by d-axis energization is not taken away by the rotating electrical machine 21, the rotating electrical machine 21 is reconnected to the cooling circuit 11, and the refrigerant is also circulated through the rotating electrical machine 21. Thereby, the heat generated by the rotating electrical machine 21 due to d-axis energization also contributes to the rise in the refrigerant temperature. Therefore, the heat pump system 100 of the present embodiment can particularly quickly raise the refrigerant temperature T1 and can particularly shorten the time until the compressor 33 becomes startable.

[0079] FIG. 8 shows the state in which the target temperature T3 of the heat pump system 100 (compressor 33) is reached after the heat pump system 100 (compressor 33) is started. * 8, when the heat pump system 100 is started and heat transport to the battery is started, the controller 102 sets the target refrigerant temperature T1 in step S20. * to a third temperature TH3, and the d-axis current supply is continued. Here, the third temperature TH3 is the coolant temperature T1 for raising the battery to a temperature at which rapid charging can be performed without causing electrodeposition by the d-axis current supply. In addition, in step S21, the controller 102 continues to compare the rotating electric machine temperature T2 with the coolant temperature T1.

[0080] If it is determined in step S21 that the rotating electric machine temperature T2 is equal to or higher than the coolant temperature T1, the process proceeds to step S22, where the controller 102 determines whether or not a mode change is required.

[0081] When the current mode is the second mode M2 ​​in step S22, the process proceeds to step S23, where the controller 102 changes the mode of the heat pump system 100 to the first mode M1. On the other hand, when the current mode is the first mode M1 in step S22, the controller 102 skips step S23 and continues the first mode M1. That is, even after the start of the heat pump system 100, when the rotating machine temperature T2 is equal to or higher than the refrigerant temperature T1, the controller 102 sets the mode of the heat pump system 100 to the first mode M1.

[0082] On the other hand, when it is determined in step S21 that the rotating electric machine temperature T2 is lower than the coolant temperature T1, the process proceeds to step S24, where the controller 102 determines whether or not a mode change is required.

[0083] Specifically, when the current mode is the first mode M1 in step S24, the process proceeds to step S25, where the controller 102 changes the mode of the heat pump system 100 to the second mode M2. On the other hand, when the current mode is the second mode M2 ​​in step S24, the controller 102 skips step S25 and continues the second mode M2. That is, even after the start of the heat pump system 100, when the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the controller 102 changes the mode of the heat pump system 100 to the second mode M2 ​​and separates the rotating electric machine 21 from the cooling circuit 11.

[0084] Then, in step S26, the controller 102 sets the heating target temperature T3 to the target heating target temperature T3 * That is, the controller 102 compares the current battery temperature with the battery temperature at which fast charging can be performed without causing electrodeposition.

[0085] In step S26, the heating target temperature T3 is set to the target heating target temperature T3 * If the temperature T3 is lower than the target temperature T3 in step S26, the process returns to step S21, and the controller 102 appropriately repeats the comparison between the rotating electrical machine temperature T2 and the coolant temperature T1 and the determination of the mode switching. * When the temperature reaches the above temperature, the process proceeds to step S27, and the controller 102 ends the d-axis current supply. At this time, if heat transport by the heat pump system 100 is not required other than to warm up the battery, the controller 102 can stop the compressor 33 and the second pump 37.

[0086] In this way, even after the compressor 33 is started, the controller 102 switches the mode of the heat pump system 100 between the first mode M1 and the second mode M2 ​​depending on the magnitude relationship between the rotating electric machine temperature T2 and the refrigerant temperature T1. Therefore, in the heat pump system 100, the battery temperature can be raised to the target temperature (target heating target temperature T3) more quickly than when the first mode M1 is continued to heat the battery. *) This increases the amount of quick charging at extremely low temperatures. In addition, the output performance of the battery in an extremely low temperature environment is improved. In addition, the thermal efficiency (energy efficiency) of the heat pump system 100 is improved.

[0087] In addition, in FIG. 6 and FIG. 8, the rotating electrical machine temperature T2 is usually set to the heat resistance threshold value TH OH Since the rotating electrical machine temperature T2 and the heat resistance threshold TH OH Although the comparison is omitted, even if the rotating electrical machine temperature T2 is lower than the coolant temperature T1, the rotating electrical machine temperature T2 is higher than the heat resistance threshold TH OH In this case, it is preferable to connect the rotating electrical machine 21 to the cooling circuit 11 .

[0088] Fig. 9 is a flowchart showing mode switching of the heat pump system 100 while the vehicle is traveling. As shown in Fig. 9, when the electric powertrain has heat, such as when the electric vehicle is traveling, the controller 102 switches the mode of the heat pump system 100 to the third mode M3 as a general rule in step S30. At this time, the controller 102 controls the electric powertrain and the like so that the refrigerant temperature T1 is maintained at the second temperature TH2.

[0089] Thereafter, when the remaining capacity of the battery becomes low and charging (quick charging) becomes necessary, the controller 102 sets the target refrigerant temperature T1 in step S31 to warm the battery in preparation for quick charging. * to the third temperature TH3. In step S32, the controller 102 starts d-axis current application and heat transport by the heat pump system 100. In step S33, the controller 102 compares the rotating electrical machine temperature T2 with the refrigerant temperature T1.

[0090] When the rotating electric machine temperature T2 is equal to or higher than the refrigerant temperature T1 in step S33, the process proceeds to step S34, where the controller 102 maintains the heat pump system 100 in the third mode M3. As a result, the battery is warmed by both the heat generated by the rotating electric machine 21 and the heat generated by the inverter 22 due to the d-axis current supply.

[0091] On the other hand, if it is determined in step S33 that the rotating electrical machine temperature T2 is lower than the coolant temperature T1, the process proceeds to step S35. In step S35, the controller 102 sets the heat resistance threshold TH OH Then, the rotating electrical machine temperature T2 is compared with the heat resistance threshold TH OH If the temperature is lower than the predetermined temperature, the process proceeds to step S36, and the controller 102 switches the mode of the heat pump system 100 to the fourth mode M4. That is, the controller 102 disconnects the rotating electric machine 21 from the cooling circuit 11.

[0092] In step S35, the rotating electrical machine temperature T2 is equal to or lower than the heat resistance threshold TH OH If this is the case, the process proceeds to step S34, and the third mode M3 is maintained. This maintains the circulation of the coolant to the rotating electric machine 21, and the cooling of the rotating electric machine 21 is continued.

[0093] Thereafter, in step S37, the controller 102 compares, for example, the refrigerant temperature T1 with the third temperature TH3. If the refrigerant temperature T1 is lower than the third temperature TH3 in step S37, the process returns to step S33, and the controller 102 continues to determine whether to switch the mode of the heat pump system 100 based on the rotating electric machine temperature T2 and the refrigerant temperature T1. On the other hand, if the refrigerant temperature T1 becomes equal to or higher than the third temperature TH3 in step S37, the process proceeds to step S38 in order to maintain that temperature. Then, in step S38, the controller 102 changes or maintains the mode of the heat pump system 100 to the third mode, and ends the d-axis current supply in step S39. As a result, the battery temperature reaches a temperature suitable for rapid charging (target heating target temperature T3) by the time the electric vehicle arrives at the charging spot. *) to reach

[0094] Thus, in the heat pump system 100 of this embodiment, even when the electric vehicle is running and the electric powertrain has heat, heat can be generated in the electric powertrain by the d-axis current supply, and the heat can be used to heat the heating target 10, such as a battery. Even when the battery, etc. is heated by the d-axis current supply while the electric vehicle is running, the heat pump system 100 switches the mode of the heat pump system 100 according to the magnitude relationship between the rotating electric machine temperature T2 and the refrigerant temperature T1, and appropriately separates the rotating electric machine 21 from the cooling circuit 11.

[0095] 10 is a graph showing changes in refrigerant temperature T1 in the third mode M3 and the fourth mode M4. Here, the time when the battery level becomes low and charging becomes necessary is defined as "t3", and the time when the electric vehicle arrives at the charging spot is defined as "t4".

[0096] As shown in Fig. 10, while the electric vehicle is running, the coolant temperature T1 is maintained at the second temperature TH2. Then, at time t3, it is determined that the battery needs to be charged, and the target coolant temperature T1 * When the third mode M3 is maintained when the battery is set to the third temperature TH3, depending on the remaining charge of the battery and the distance to the charging spot, the coolant temperature T1 may not rise to the third temperature TH3 by the time of arrival at the charging spot t4. In other words, if the normal third mode M3 is maintained, the battery temperature may not reach a temperature suitable for rapid charging (target heating target temperature T3 * ) may not be able to reach the coolant temperature T1. This is because when the rotating electrical machine temperature T2 is lower than the coolant temperature T1, the heat generated by the d-axis current flow is used to increase the temperature of the rotating electrical machine.

[0097] On the other hand, when the mode is switched to the fourth mode M4 and the rotating electric machine 21 is separated from the cooling circuit 11 within a range in which the rotating electric machine 21 does not exceed its heat resistance limit, the heat generated in the inverter 22 by the d-axis current supply is transported to the battery without being taken by the rotating electric machine 21. For this reason, as described above, even when the electric vehicle is traveling, by appropriately switching from the third mode M3 to the fourth mode M4 according to the magnitude relationship between the rotating electric machine temperature T2 and the refrigerant temperature T1, the refrigerant temperature T1 can be quickly raised to the third temperature TH3 before arriving at the charging spot, and the battery can be brought to a temperature suitable for rapid charging.

[0098] Furthermore, in this embodiment, when the rotating electric machine temperature T2 becomes equal to or higher than the refrigerant temperature T1 and the heat generated by the d-axis current supply is not absorbed by the rotating electric machine 21, the rotating electric machine 21 is reconnected to the cooling circuit 11, and the refrigerant is circulated to the rotating electric machine 21 as well. As a result, the heat generated by the rotating electric machine 21 by the d-axis current supply also contributes to increasing the temperatures of the refrigerant and the battery. Therefore, the heat pump system 100 of this embodiment can particularly quickly increase the refrigerant temperature T1 to the third temperature TH3, and make the battery at a temperature suitable for rapid charging.

[0099] This increases the amount of quick charging of the battery, and also improves the thermal efficiency (energy efficiency) of the heat pump system 100.

[0100] Here, an example has been described in which the mode of the heat pump system 100 is switched between the third mode M3 and the fourth mode M4 while the electric vehicle is traveling, but the present invention is not limited to this. As long as the rotating electric machine 21 and the inverter 22 do not exceed their respective heat resistance temperatures, the mode may be switched from the third mode M3 to the second mode M2, and further the external heat exchanger 24 may be temporarily disconnected from the cooling circuit 11. Similarly, the mode may be temporarily switched to the second mode M2 ​​while the fourth mode M4 is selected.

[0101] [Variations] Below, a modification of the above embodiment will be described.

[0102] 11 is a flowchart of the first modification. In the first modification, when the heat pump system 100 is started in an extremely low temperature environment, the carrier frequency f c In this case, for example, step S50 is inserted between steps S10 and S11 in the above embodiment (see FIG. 6) as shown in FIG 11. The other steps are the same as those in the above embodiment.

[0103] In step S50, the controller 102 controls the carrier frequency f c to a carrier frequency f2 that is higher than the carrier frequency f1 used to drive the rotating electric machine 21. That is, the controller 102 sets the carrier frequency of the inverter 22 used when performing d-axis current supply to a higher frequency than the carrier frequency of the inverter 22 used to drive the rotating electric machine 21. As a result, the controller 102 increases switching loss, and causes the inverter 22 to generate more heat by the d-axis current supply.

[0104] In this way, the carrier frequency f of the inverter 22 c When the frequency is changed to a high frequency and the heat generated in the inverter 22 by the d-axis current is increased, the refrigerant temperature T1 increases more quickly. As a result, the heat pump system 100 (compressor 33) can be started up more quickly than in the above embodiment.

[0105] In this case, when the heat pump system 100 is started in a very low temperature environment with the rotation of the rotating electric machine 21 stopped, the carrier frequency f c In the above example, the carrier frequency f of the inverter 22 is changed to a frequency higher than the normal frequency, but the present invention is not limited to this. For example, the carrier frequency f of the inverter 22 is changed to a frequency higher than the normal frequency only when the mode of the heat pump system 100 is switched to the second mode M2. c may be changed to a higher frequency than normal.

[0106] In addition, when the heat pump system 100 is started in a very low temperature environment with the rotating electric machine 21 stopped, the carrier frequency f c However, the present invention is not limited to this. For example, the carrier frequency f c In the case where the carrier frequency f is changed, when it becomes necessary to transport the heat generated by the d-axis current supply by the heat pump system 100 to the heating target 10 even during driving, c It is preferable to change the carrier frequency f to a higher frequency than usual. Also, only when switching from the third mode M3 to the fourth mode M4 (or the second mode M2), the carrier frequency f c may be changed to a higher frequency than normal.

[0107] Fig. 12 is a flowchart of the second modified example. The second modified example is an example in which the flow rate of the refrigerant in the cooling circuit 11 is adjusted when the heat pump system 100 is started in an extremely low temperature environment. In this case, for example, as shown in Fig. 12, when the mode of the heat pump system 100 is switched to the second mode M2, the controller 102 continues to execute step S60. The other steps are the same as those of the above embodiment.

[0108] In step S60, the controller 102 separates the rotating electric machine 21 from the cooling circuit 11, and then reduces the opening of the valve 29 (or the valve 27) to reduce the flow rate of the refrigerant flowing through the cooling circuit 11. That is, the controller 102 reduces the flow rate of the refrigerant when the d-axis current is applied compared to the flow rate of the refrigerant when the rotating electric machine 21 is driven. This lengthens the time that the refrigerant contacts the inverter 22. As a result, more heat generated in the inverter 22 by the d-axis current is likely to be transferred to the refrigerant in the portion that contacts the inverter 22. As a result, the refrigerant that has become partially hot flows into the chiller 23, and the rise in the refrigerant temperature T1 measured upstream of the chiller 23 becomes faster. Therefore, the heat pump system 100 (compressor 33) can be started up more quickly than in the above embodiment.

[0109] Although the flow rate of the refrigerant circulating through the cooling circuit 11 is reduced only when the mode of the heat pump system 100 is changed to the second mode M2, this is not limiting. For example, when starting the heat pump system 100 in an extremely low temperature environment, the flow rate of the refrigerant circulating through the cooling circuit 11 may be reduced in advance regardless of whether the first mode M1 or the second mode M2 ​​is selected.

[0110] In addition, although the flow rate of the refrigerant flowing through the cooling circuit 11 is reduced when the heat pump system 100 is started in an extremely low temperature environment, the present invention is not limited to this. For example, even during traveling, when it becomes necessary to transport heat generated by the d-axis current supply by the heat pump system 100 to the target 10 to be heated, the flow rate of the refrigerant flowing through the cooling circuit 11 may be reduced in the same manner as described above within a range in which cooling of the rotating electric machine 21 and the inverter 22 is not hindered.

[0111] The above first and second modified examples can be implemented simultaneously.

[0112] In the above embodiment and each modification, the actions and the like occurring in the case where the object to be heated 10 is a battery have been described, but similar actions and the like can be obtained when the object to be heated 10 is a heater core. Specifically, when the above embodiment and each modification accelerate the start of the heat pump system 100 and the temperature rise of the heater core, the heating performance (fast heating performance) at extremely low temperatures and the like is improved. In addition, the thermal efficiency (energy efficiency) of heating is improved.

[0113] As described above, the control method of the heat pump system according to the above embodiment and each modification is a control method of a heat pump system in which, in a heat pump system 100 including an electric power train including a rotating electric machine 21 and an inverter 22 that drives the rotating electric machine 21, a cooling circuit 11 that cools the electric power train, and a heat transport circuit 12 that is thermally connected to the cooling circuit 11 and transports heat generated in the electric power train to a target 10 to be heated using a compressor 33, heat is generated in the electric power train by d-axis current supply that increases the d-axis current of the rotating electric machine 21 when heating the target 10 to be heated. In this control method of a heat pump system, a rotating electric machine temperature T2 that is the temperature of the rotating electric machine 21 is obtained, a refrigerant temperature T1 that is the temperature of the refrigerant circulating in the cooling circuit 11 is obtained, and when the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the rotating electric machine 21 is separated from the cooling circuit 11, and the refrigerant temperature T1 is increased by d-axis current supply using heat generated in the inverter 22 out of the rotating electric machine 21 and the inverter 22.

[0114] In this way, when the heat generated in the electric power train by the d-axis current is transported by the heat pump system 100 to heat the target 10, if the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the rotating electric machine 21 is disconnected from the cooling circuit 11, so that the heat generated in the inverter 22 by the d-axis current is not taken by the rotating electric machine 21. As a result, the target 10 to be heated, such as a battery, can be heated more quickly than before. For example, in an extremely low temperature environment, the start-up of the heat pump system 100 can be accelerated. The same applies when the electric vehicle is running.

[0115] In the control method for the heat pump system according to the above embodiment and each of the modified examples, a first temperature TH1 is set for the refrigerant temperature T1 to determine whether or not the compressor 33 can be started. When the refrigerant temperature T1 is lower than the first temperature TH1 and the rotating motor temperature T2 is lower than the refrigerant temperature T1, the rotating motor 21 is disconnected from the cooling circuit 11. When the refrigerant temperature T1 becomes equal to or higher than the first temperature TH1 using heat generated in the inverter 22 by the d-axis current flow, the compressor 33 is started.

[0116] In this way, in an extremely low temperature environment where the refrigerant temperature T1 is lower than the first temperature TH1, when the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the rotating electric machine 21 is separated from the cooling circuit 11, thereby particularly speeding up the start of the heat pump system 100. As a result, the object to be heated, such as a battery, can be heated more quickly than before.

[0117] In the control method of the heat pump system according to the above embodiment and each modification, the current refrigerant temperature T1 is equal to or higher than the temperature (TH1) at which the compressor can be started, and the target refrigerant temperature T1 (=TH2) is set to a value higher than the current refrigerant temperature T1. * When (=TH3) is set, the rotating electric machine temperature T2 and the coolant temperature T1 are compared, and if the rotating electric machine temperature T2 is lower than the coolant temperature T1, the rotating electric machine 21 is separated from the cooling circuit 11, and the coolant temperature T1 is increased to the target coolant temperature T1 using heat generated in the inverter 22 by the d-axis current supply. * (=TH3).

[0118] In this way, even during driving or the like when the current refrigerant temperature T1 is equal to or higher than the temperature (TH1) at which the compressor can be started, the target refrigerant temperature T1 (=TH2) higher than the current refrigerant temperature T1 is set. * When (=TH3) is set, it becomes necessary to heat the heating target 10 by applying current to the d-axis. Therefore, as described above, by disconnecting the rotating electric machine 21 from the cooling circuit 11 when the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the heating target 10, such as a battery, can be heated more quickly than before.

[0119] In the control method for the heat pump system according to the above embodiment and each modified example, when the rotating machine temperature T2 becomes equal to or higher than the refrigerant temperature T1, the rotating machine 21 that was disconnected from the cooling circuit 11 is reconnected to the cooling circuit 11.

[0120] In this way, when the rotating electric machine temperature T2 becomes equal to or higher than the refrigerant temperature T1, if the rotating electric machine 21 that was disconnected from the cooling circuit 11 is reconnected to the cooling circuit 11, the heat generated by the rotating electric machine 21 due to the d-axis current also contributes to increasing the temperature of the refrigerant and the object to be heated 10. As a result, the object to be heated 10, such as a battery, can be heated more quickly than ever before.

[0121] In the control method of the heat pump system according to the above embodiment and each modification, the heat resistance threshold TH OH Even if the rotating electrical machine temperature T2 is lower than the coolant temperature T1, the rotating electrical machine temperature T2 is set to the heat resistance threshold TH OH If the above is the case, the rotating electrical machine 21 is connected to the cooling circuit 11 .

[0122] This makes it possible to appropriately determine the timing to disconnect the rotating electric machine 21 from the cooling circuit 11 and temporarily stop cooling of the rotating electric machine 21. As a result, the rotating electric machine 21 can be disconnected from the cooling circuit 11 at an appropriate timing for starting up the heat pump system 100 and for increasing the temperature of the object to be heated 10, without overheating the rotating electric machine 21.

[0123] In the control method of the heat pump system according to the above embodiment and each of the modified examples (particularly the first modified example), the carrier frequency of the inverter 22 used when performing d-axis current supply is set to a higher frequency than the carrier frequency of the inverter 22 used when driving the rotating motor 21.

[0124] In this way, when the carrier frequency of the inverter 22 used when performing the d-axis current supply is set to a high frequency, the switching loss increases, and the d-axis current supply generates more heat in the inverter 22. As a result, the rise in the refrigerant temperature T1 and the rise in the temperature of the object to be heated 10 become particularly rapid.

[0125] In the control method for the heat pump system according to the above embodiment and each of the modified examples (particularly the second modified example), the flow rate of the refrigerant is reduced when d-axis current is applied, compared to the flow rate of the refrigerant when the rotating electric machine 21 is driven.

[0126] In this way, by reducing the flow rate of the refrigerant when d-axis current is applied, more heat generated in the inverter 22 by the d-axis current is transferred to the refrigerant in the portion in contact with the inverter 22. As a result, the refrigerant that has become partially hot flows into the chiller 23. As a result, the rise in the refrigerant temperature T1 and the rise in the temperature of the object to be heated 10 become particularly rapid.

[0127] The control device of the heat pump system in the above embodiments and each modified example is a control device (controller 102) of a heat pump system in a heat pump system 100 including an electric powertrain including a rotating electric machine 21 and an inverter 22 that drives the rotating electric machine 21, a cooling circuit 11 that cools the electric powertrain, and a heat transport circuit 12 that is thermally connected to the cooling circuit 11 and transports heat generated in the electric powertrain to a target to be heated 10 using a compressor 33, which generates heat in the electric powertrain by supplying d-axis current that increases the d-axis current of the rotating electric machine 21 when heating the target to be heated 10. A control device (controller 102) of this heat pump system acquires a rotating machine temperature T2, which is the temperature of the rotating machine 21, and acquires a refrigerant temperature T1, which is the temperature of the refrigerant circulating through the cooling circuit 11.When the rotating machine temperature T2 is lower than the refrigerant temperature T1, the rotating machine 21 is disconnected from the cooling circuit 11, and by applying current to the d-axis, the refrigerant temperature T1 is raised by using heat generated in the inverter 22, which is one of the rotating machine 21 and the inverter 22.

[0128] In this way, when the heat generated in the electric power train by the d-axis current is transported by the heat pump system 100 to heat the target 10, if the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the heat generated in the inverter 22 by the d-axis current is not taken by the rotating electric machine 21 by isolating the rotating electric machine 21 from the cooling circuit 11. As a result, the target 10 to be heated, such as a battery, can be heated more quickly than ever before.

[0129] The heat pump circuit according to the above embodiment and each of the modified examples is a heat pump circuit 101 including an electric power train including a rotating electric machine 21 and an inverter 22 that drives the rotating electric machine 21, a cooling circuit 11 that cools the electric power train, and a heat transport circuit 12 that is thermally connected to the cooling circuit 11 and transports heat generated in the electric power train to a target 10 to be heated using a compressor 33. The heat pump circuit 101 includes a bypass 28 that is a flow path that connects an inlet of the refrigerant circulating in the cooling circuit 11 to the rotating electric machine 21 and an outlet of the refrigerant from the rotating electric machine 21, and a valve 29 that separates the rotating electric machine 21 from the cooling circuit 11 by flowing the refrigerant through the bypass 28 when a rotating electric machine temperature T2 that is the temperature of the rotating electric machine 21 is lower than a refrigerant temperature T1 that is the temperature of the refrigerant circulating in the cooling circuit 11.

[0130] In this way, when the heat pump circuit 101 has a configuration for isolating the rotating electric machine 21 from the cooling circuit 11 when the rotating electric machine temperature T2 is lower than the refrigerant temperature T1, the heat generated in the inverter 22 by the d-axis current flow is not taken away by the rotating electric machine 21. As a result, the target to be heated, such as a battery, can be heated more quickly than ever before.

[0131] Although the embodiments of the present invention have been described above, the configurations described in the above embodiments and the respective modified examples merely represent some of the application examples of the present invention and are not intended to limit the technical scope of the present invention. [Explanation of symbols]

[0132] 10: heating target, 11: cooling circuit, 12: heat transport circuit, 13: first heat transport circuit, 14: second heat transport circuit, 21: rotating electric machine, 22: inverter, 23: chiller, 24: external heat exchanger, 25: first pump, 26: bypass, 27: valve, 28: bypass, 29: valve, 30: temperature sensor, 31: temperature sensor, 33: compressor, 34: water-cooled condenser, 35: receiver, 36: expansion valve, 37: second pump, 38: temperature sensor, 100: heat pump system, 101: heat pump circuit, 102: controller

Claims

1. A heat pump system including an electric powertrain including a rotating electric machine and an inverter that drives the rotating electric machine, a cooling circuit that cools the electric powertrain, and a heat transport circuit that is thermally connected to the cooling circuit and transports heat generated in the electric powertrain to an object to be heated by using a compressor, the heat pump system control method comprising the steps of: generating heat in the electric powertrain by d-axis current supply that increases a d-axis current of the rotating electric machine when heating the object to be heated, the method comprising the steps of: A rotating electric machine temperature, which is a temperature of the rotating electric machine, is acquired; A refrigerant temperature, which is a temperature of the refrigerant circulating in the cooling circuit, is acquired; when the temperature of the rotating electric machine is lower than the temperature of the refrigerant, the rotating electric machine is separated from the cooling circuit; the d-axis current is applied to the rotating electric machine and the inverter, and the heat generated in the inverter is used to increase the temperature of the refrigerant. A method for controlling a heat pump system.

2. A control method for a heat pump system according to claim 1, A first temperature is set for the refrigerant temperature to determine whether or not the compressor can be started; when the coolant temperature is lower than the first temperature and the rotating electric machine temperature is lower than the coolant temperature, the rotating electric machine is separated from the cooling circuit; When the refrigerant temperature becomes equal to or higher than the first temperature by using heat generated in the inverter by the d-axis current supply, the compressor is started. A method for controlling a heat pump system.

3. A control method for a heat pump system according to claim 1, comparing the rotating electrical machine temperature with the coolant temperature when the current coolant temperature is equal to or higher than the temperature at which the compressor can be started and a target coolant temperature higher than the current coolant temperature is set; when the temperature of the rotating electric machine is lower than the temperature of the refrigerant, the rotating electric machine is separated from the cooling circuit; the refrigerant temperature is brought closer to the target refrigerant temperature by using heat generated in the inverter by the d-axis current supply; A method for controlling a heat pump system.

4. A control method for a heat pump system according to any one of claims 1 to 3, when the temperature of the rotating electric machine becomes equal to or higher than the refrigerant temperature, the rotating electric machine that has been disconnected from the cooling circuit is reconnected to the cooling circuit. A method for controlling a heat pump system.

5. A control method for a heat pump system according to any one of claims 1 to 3, setting a heat resistance threshold value for the rotating electrical machine temperature; even if the temperature of the rotating electric machine is lower than the coolant temperature, when the temperature of the rotating electric machine is equal to or higher than the heat resistance threshold value, the rotating electric machine is connected to the cooling circuit. A method for controlling a heat pump system.

6. A control method for a heat pump system according to any one of claims 1 to 3, a carrier frequency of the inverter used when energizing the d-axis is set to a higher frequency than a carrier frequency of the inverter used when driving the rotating electric machine; A method for controlling a heat pump system.

7. A control method for a heat pump system according to any one of claims 1 to 3, a flow rate of the coolant when the d-axis current is applied is reduced compared to a flow rate of the coolant when the rotating electric machine is driven. A method for controlling a heat pump system.

8. A heat pump system including an electric powertrain including a rotating electric machine and an inverter that drives the rotating electric machine, a cooling circuit that cools the electric powertrain, and a heat transport circuit that is thermally connected to the cooling circuit and transports heat generated in the electric powertrain to an object to be heated by using a compressor, the heat pump system control device generating heat in the electric powertrain by d-axis current supply that increases a d-axis current of the rotating electric machine when heating the object to be heated, comprising: A rotating electric machine temperature, which is a temperature of the rotating electric machine, is acquired; A refrigerant temperature, which is a temperature of the refrigerant circulating in the cooling circuit, is acquired; when the temperature of the rotating electric machine is lower than the temperature of the refrigerant, the rotating electric machine is separated from the cooling circuit; the d-axis current is applied to the rotating electric machine and the inverter, and the heat generated in the inverter is used to increase the temperature of the refrigerant. Heat pump system control device.

9. A heat pump circuit including: an electric power train including a rotating electric machine and an inverter that drives the rotating electric machine; a cooling circuit that cools the electric power train; and a heat transport circuit that is thermally connected to the cooling circuit and transports heat generated in the electric power train to a target to be heated by using a compressor, a bypass that is a flow path connecting an inlet of the coolant circulating through the cooling circuit to the rotating electric machine and an outlet of the coolant from the rotating electric machine; a valve that separates the rotating electric machine from the cooling circuit by causing the coolant to flow through the bypass when a rotating electric machine temperature that is a temperature of the rotating electric machine is lower than a coolant temperature that is a temperature of the coolant; A heat pump circuit comprising:

Images