Electric vehicle and method for controlling electric vehicle

Abstract

Provided is an electric vehicle comprising: a battery; a cooling water passage through which cooling water for exchanging heat with the battery flows; and an air flow passage through which air for exchanging heat with the battery flows. In the electric vehicle, the cooling water passage passes through one of an upper portion and a lower portion of the battery, and the air flow passage passes through the other of the upper portion and the lower portion of the battery.

Description

Electric vehicle and control method for electric vehicle

[0001] The present invention relates to an electric vehicle and a method for controlling an electric vehicle.

[0002] A temperature control system that uses coolant to control the temperature of a battery in an electric vehicle is known. However, this temperature control system cools only one side of the battery, which can easily cause temperature unevenness in the battery, resulting in a decrease in the battery's energy efficiency and charging performance, and possibly battery degradation.

[0003] In response to this, JP6418051B2 discloses a temperature control device for a vehicle battery that controls the battery temperature by blowing air into the battery. This temperature control device controls the battery temperature by blowing air that has been temperature-controlled by an air conditioner into the battery.

[0004] In the electric vehicle described in JP6418051B2, the temperature of the battery is regulated by blowing air, but because the heat capacity of air is small, uneven battery temperature is likely to occur, which may result in a decrease in the battery's energy efficiency and charging performance, and may cause battery deterioration.

[0005] The present invention has been made in consideration of the above-mentioned problems, and aims to provide an electric vehicle and a control method for an electric vehicle that reduce temperature unevenness in a battery and suppress a decrease in the energy efficiency and charging performance of the battery, as well as battery degradation.

[0006] According to one aspect of the present invention, there is provided an electric vehicle including a battery, a cooling water passage through which coolant flows to exchange heat with the battery, and an air flow passage through which air flows to exchange heat with the battery, wherein the cooling water passage passes through one of an upper portion and a lower portion of the battery, and the air flow passage passes through the other of the upper portion and the lower portion of the battery.

[0007] Fig. 1 is a schematic configuration diagram of an electric vehicle system according to one embodiment. Fig. 2 is a side view of the electric vehicle at a connection portion between the vehicle cabin and the battery pack and air conditioning unit. Fig. 3 is a block diagram showing the flow of air and coolant in battery temperature regulation control. Fig. 4 is a control block diagram of water-cooling control. Fig. 5 is a control block diagram of air-cooling control. Fig. 6 is a flowchart of water-cooling control. Fig. 7 is a flowchart of air-cooling control.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0009] 1 is a schematic diagram of an electric vehicle system 100 according to one embodiment. The electric vehicle system 100 is a temperature control system that controls the temperature of a battery mounted on an electric vehicle according to one embodiment of the present invention. The electric vehicle here may be, for example, a hybrid vehicle or an electric vehicle.

[0010] The electric vehicle system 100 includes a cooling water passage 1 through which coolant flows, an air conditioning circuit 2 through which air conditioning refrigerant (air) flows, an air flow passage 8 (see FIG. 2 ), and a controller 50. A battery pack (battery) 10, a heater 11, a chiller 21, an electric powertrain (ePT) unit 30, and a radiator 40 are arranged on the cooling water passage 1. An air conditioning unit 20, a chiller 21, and a condenser 22 are arranged on the air conditioning circuit 2. The air flow passage 8 is connected to the interior of a vehicle compartment 81 and passes above the battery pack (battery) 10 ( FIG. 2 ).

[0011] The cooling water passage 1 is a cooling water circuit through which cooling water flows to warm or cool the battery in the battery pack 10. The cooling water passage 1 includes first and second valves 61 and 62 that switch the circuit through which the cooling water flows, and first and second pumps 71 and 72 that circulate the cooling water. The cooling water passage 1, the heater 11, the chiller 21, the electric powertrain (ePT) unit 30, and the radiator 40 on the cooling water passage 1, the first and second valves 61 and 62, and the first and second pumps 71 and 72 constitute a battery water-cooling mechanism (hereinafter simply referred to as the water-cooling mechanism). The cooling water passage 1 near the inlet of the battery pack 10 is provided with a temperature sensor (not shown) that detects the temperature of the cooling water flowing through the cooling water passage 1. The detected temperature of the cooling water is transmitted to the controller 50.

[0012] The air conditioning circuit 2 is a pipe through which a refrigerant (air) for cooling or heating the vehicle interior 81 (see FIG. 2) circulates. The air conditioning circuit 2, the air conditioning unit 20, the chiller 21, and the condenser 22 on the air conditioning circuit 2 constitute an air conditioning device.

[0013] The battery pack 10 is, for example, a rechargeable lithium-ion battery, and includes multiple battery modules (not shown) each having multiple battery cells connected in series or in a combination of series and parallel. The multiple battery modules are connected in parallel or series to form a high-output, large-capacity battery. The battery formed by the multiple battery modules supplies power to an electric powertrain (ePT) unit 30 for driving a motor. Hereinafter, the battery pack 10 will also be referred to as the battery 10.

[0014] The battery 10 is provided on a cooling water passage 1, and the cooling water passage 1 passes under the battery 10. Here, the lower part of the battery 10 includes not only the lower part inside the battery 10 but also the lower surface of the battery 10, and the cooling water passage 1 may pass under the battery 10 or may pass under the lower surface of the battery 10. The battery 10 is warmed or cooled by the cooling water passage 1, through which heated or cooled coolant flows, passing under the battery 10.

[0015] An air intake port 12 connected to an air flow path 8 (see FIG. 2) described later and an exhaust port 13 connected to an exhaust passage 9 (see FIG. 2) described later are formed on the top surface of the battery 10. As described later, the air flow path 8 passes through the upper part of the battery 10.

[0016] The battery 10 is provided with a plurality of temperature sensors for detecting the temperature of the battery 10 and a pressure sensor for detecting the pressure of the battery 10 (neither of which is shown), which detect the temperatures of the upper and lower parts of the battery 10 and the pressure inside the battery 10. The detected temperature and pressure of the battery 10 are transmitted to the controller 50.

[0017] The heater 11 is disposed on the cooling water passage 1 downstream of the battery 10. The heater 11 heats the cooling water discharged from the battery 10. The heated cooling water circulates through the cooling water passage 1 and is supplied to the battery 10. The operation of the heater 11 is controlled by a controller 50, which activates the heater 11 when it is necessary to raise the temperature of the battery 10.

[0018] The air conditioning unit 20 is disposed on an air conditioning circuit 2 through which a refrigerant (air) circulates, and includes a compressor, an evaporator, an expansion valve, a blower, and other components (not shown). In the air conditioning unit 20, the refrigerant (air) flowing through the air conditioning circuit 2 is compressed by the compressor, and the compressed refrigerant is supplied to a condenser 22. The condenser 22 condenses and liquefies the compressed refrigerant and supplies it to the air conditioning unit 20. The refrigerant supplied from the condenser 22 is rapidly expanded by an expansion valve of the air conditioning unit 20 to become low-temperature, low-pressure refrigerant. The low-temperature, low-pressure refrigerant is supplied to the evaporator and chiller 21. The evaporator evaporates the refrigerant (air) flowing through the air conditioning circuit 2 and supplies the evaporated refrigerant to the compressor. The operation of the compressor, expansion valve, blower, and other components constituting the air conditioning unit 20 is controlled by a controller 50.

[0019] The chiller 21 is provided on the cooling water passage 1 connecting the upstream of the battery 10 and the downstream of the heater 11, and is also arranged on the air conditioning circuit 2. The chiller 21 exchanges heat between the refrigerant in the air conditioning circuit 2, which has been made low temperature and low pressure by an expansion valve, and the heat of the cooling water flowing through the cooling water passage 1, thereby adjusting the temperature of the cooling water.

[0020] The electric powertrain (ePT) unit 30 includes a DC-DC converter, an inverter, a traction motor, etc. The ePT unit 30 is arranged in parallel with the chiller 21 on the cooling water passage 1. Heat from the ePT unit 30 is discarded into the cooling water flowing through the cooling water passage 1.

[0021] The radiator 40 is a cooling mechanism that exchanges heat between the coolant flowing through the cooling water passage 1 and the atmosphere, and is disposed on the cooling water passage 1 in parallel with the chiller 21 and the ePT unit 30. A fan 41 for the radiator 40 is provided near the radiator 40, and operating the fan 41 can cool the coolant flowing through the cooling water passage 1. The radiator 40 is also disposed near a grille shutter 42 that introduces airflow into the vehicle, and when the grille shutter 42 is open, the airflow hits the radiator 40, thereby cooling the coolant in the cooling water passage 1. The operation of the fan 41 and the opening and closing of the grille shutter 42 are controlled by a controller 50.

[0022] The first and second valves 61, 62 switch the circuit through which the cooling water flows. The first valve 61 is a three-way valve provided in the cooling water passage 1 upstream of the chiller 21, and controls the flow rate of the cooling water passing through the chiller 21. The second valve 62 is a three-way valve provided in the cooling water passage 1 between the radiator 40 and the ePT unit 30, and controls the flow rate of the cooling water passing through the ePT unit 30. The opening degrees of the first and second valves 61, 62 are controlled by the controller 50.

[0023] The first and second pumps 71, 72 are water pumps that circulate the cooling water flowing through the cooling water passage 1. The first pump 71 is provided in the cooling water passage 1 between the heater 11 and the first valve 61, and controls the flow rate of the cooling water supplied to the first valve 61. The second pump 72 is provided in the cooling water passage 1 between the radiator 40 and the second valve 62, and controls the flow rate of the cooling water supplied to the second valve 62. The operations of the first and second pumps 71, 72 are controlled by the controller 50.

[0024] FIG. 2 is a diagram showing the connection portion between the vehicle compartment 81 and the battery 10 and the air conditioning unit 20, and is a side view of the electric vehicle on which the electric vehicle system 100 is mounted.

[0025] As shown in FIG. 2 , the air conditioning unit 20 is connected to the vehicle compartment 81 via a pipe 23. As described above, the air conditioning unit 20 includes a blower (not shown), which supplies air whose temperature has been adjusted in the air conditioning circuit 2 into the vehicle compartment 81 via the pipe 23. The operation of the air conditioning unit 20 (blower, compressor, expansion valve, etc.) is controlled by a controller 50. When the air conditioning device is off, the air conditioning unit 20 does not normally operate. The vehicle compartment 81 is equipped with a temperature sensor that detects the temperature of the air in the vehicle compartment 81, a humidity sensor that detects the humidity in the vehicle compartment 81, and a pressure sensor that detects the pressure (atmospheric pressure) in the vehicle compartment 81. The detected air temperature, air humidity, and pressure in the vehicle compartment 81 are transmitted to the controller 50.

[0026] The vehicle interior 81 and the battery 10 are connected by an air flow path 8. The air flow path 8 has a conductive path 82 that connects the vehicle interior 81 and the battery 10, and a temperature control passage 83 that passes through the upper part of the battery 10. The conductive path 82 connects the vehicle interior 81 to the temperature control passage 83 in the upper part of the battery 10 via an air intake port 12 on the upper surface of the battery 10. The temperature control passage 83 is connected to the conductive path 82, passes through the upper part of the battery 10, and is connected to the exhaust passage 9 via an exhaust port 13 on the upper surface of the battery 10. Note that the upper part of the battery 10 includes not only the upper part inside the battery 10 but also the upper surface of the battery 10, and the cooling water passage 1 may pass through either the upper part inside the battery 10 or the upper surface of the battery 10.

[0027] The conduction path 82 is a pipe that introduces air from within the vehicle compartment 81 into the battery 10, and is connected to the vehicle compartment 81 and a temperature control passage 83 that passes above the battery 10. When the air from within the vehicle compartment is introduced into the battery 10 via the conduction path 82, the introduced air flows through the temperature control passage 83 above the battery 10. The air flowing through the temperature control passage 83 exchanges heat with the battery 10, thereby cooling the battery 10.

[0028] A valve 821 is provided on the conduction path 82. The valve 821 adjusts the amount of air introduced from the vehicle compartment 81 into the battery 10. For example, when the temperature of the air in the vehicle compartment 81 is lower than the temperature of the battery 10, the valve 821 is opened to introduce the air in the vehicle compartment 81 into the battery 10, thereby cooling the battery 10. Furthermore, when the pressure of the battery 10 is higher than the pressure in the vehicle compartment 81, the valve 821 is closed to prevent unintended inflow of air from the battery 10 into the vehicle compartment 81.

[0029] Furthermore, a desiccant 822 is provided in the conductive path 82. This reduces the humidity of the air introduced from the vehicle interior 81 to the battery 10. That is, when air is flowing through the battery 10, if the air humidity is high, condensation may occur, which may cause a short circuit. However, the desiccant 822 in the conductive path 82 reduces the humidity of the air introduced into the battery 10, thereby preventing a short circuit due to condensation within the battery 10.

[0030] The temperature adjustment passage 83 is a dedicated air passage provided above the battery 10 and passes above the battery 10. The temperature adjustment passage 83 is connected to the conductive path 82 via the intake port 12 on the top surface of the battery 10, and is connected to the exhaust passage 9 via the exhaust port 13 on the top surface of the battery 10. As described above, air from the vehicle interior 81 flowing through the temperature adjustment passage 83 exchanges heat with the battery 10, thereby cooling the battery 10. In this way, the temperature of the battery 10 is adjusted by the air flow path 8 (conduction path 82, temperature adjustment passage 83). The air flow path 8 and a valve 821 that adjusts the amount of air introduced into the battery 10 constitute a battery air-cooling mechanism (hereinafter also simply referred to as an air-cooling mechanism).

[0031] The exhaust passage 9 is a pipe that exhausts the air from the vehicle interior 81 that has exchanged heat with the battery 10 to the outside of the vehicle.

[0032] As described above, the temperature of the battery 10 of the electric vehicle system 100 is regulated by the coolant in the cooling water passage 1 that passes below the battery 10 and the air in the air flow passage 8 that passes above the battery 10. The temperature and flow rate of the coolant in the cooling water passage 1 that passes below the battery 10 are adjusted by the heater 11, chiller 21, ePT unit 30, radiator 40, first and second valves 61, 62, and first and second pumps 71, 72. That is, the heater 11, chiller 21, ePT unit 30, radiator 40, first and second valves 61, 62, and first and second pumps 71, 72 constitute a coolant control device that can adjust the temperature and flow rate of the coolant passing through the battery 10. The flow rate of air in the air flow passage 8 that passes above the battery 10 is adjusted by the valve 821. That is, the valve 821 constitutes an intake air control device that can adjust the amount of air passing through the battery 10.

[0033] 1, the controller 50 is configured by a computer that includes a central processing unit (CPU), a read-only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface) and is programmed to be able to execute the processes described below. Note that the controller 50 can also be configured by multiple computer hardware that executes the processes in a distributed manner.

[0034] The controller 50 acquires the temperature and pressure of the battery 10, the temperature of the cooling water in the cooling water passage 1 passing through the battery 10, and the air temperature, air humidity, and pressure in the passenger compartment 81.

[0035] The controller 50 also controls the coolant control device and the intake air control device to perform battery temperature control, which adjusts the temperature of the battery 10. Specifically, the controller 50 controls the operation of the heater 11 and the radiator 40 (fan 41 and grille shutter 42), and also controls the operation of the first and second valves 61, 62 and the first and second pumps 71, 72 to switch the pattern of the coolant circuit through which the coolant flows in the cooling water passage 1 and the flow rate of the coolant. In this way, the controller 50 controls the temperature and flow rate of the coolant in the cooling water passage 1 passing through the battery 10, thereby controlling the temperature of the battery 10. The controller 50 also controls the operation of the valve 821, which is an intake air control device, to control the amount of air in the air flow path 8 (temperature adjustment passage 83) passing through the battery 10, thereby controlling the temperature of the battery 10.

[0036] As described above, the electric vehicle system 100 includes a water-cooling mechanism and an air-cooling mechanism for adjusting the temperature of the battery 10 .

[0037] However, in electric vehicles equipped with a temperature control system that uses coolant to control the temperature of the electric vehicle's battery, the coolant cools one side of the battery, which makes it easy for temperature unevenness to occur in the battery, which may result in a decrease in the battery's energy efficiency and charging performance, or in battery deterioration.

[0038] On the other hand, in electric vehicles equipped with a temperature control system that controls the temperature of the battery by blowing air onto the battery, the heat capacity of the air is small, so uneven battery temperatures are likely to occur, which may result in a decrease in the battery's energy efficiency and charging performance, or even battery deterioration.

[0039] In contrast, in the electric vehicle (electric vehicle system 100) of this embodiment, the cooling water passage 1, through which coolant that exchanges heat with the battery 10 flows, passes below the battery 10, and the air passage 8, through which air that exchanges heat with the battery 10 flows, passes above the battery 10. As a result, the temperature of the battery 10 is regulated by the coolant flowing through the cooling water passage 1 at the bottom of the battery 10, and the temperature of the battery 10 is regulated by the air flowing through the air passage 8 at the top of the battery 10. In other words, because the temperature of the battery 10 is regulated at the top and bottom of the battery 10, the temperature distribution between the top and bottom of the battery 10 is reduced. Therefore, it is possible to reduce temperature unevenness in the battery 10, and to suppress a decrease in the energy efficiency and charging performance of the battery 10, as well as deterioration of the battery 10.

[0040] The battery temperature control will be described in detail below.

[0041] FIG. 3 is a system configuration diagram of the electric vehicle system 100, and is a block diagram showing the flow of air and coolant in battery temperature regulation control.

[0042] As shown in Fig. 3, in electric vehicle system 100, outside air is taken in by air conditioning device B1, supplied into vehicle compartment 81, and then supplied from vehicle compartment 81 to battery 10 via air-cooling mechanism B2. The air supplied to battery 10 cools battery 10 and is then discharged to the outside. Meanwhile, coolant is supplied to battery 10 from water-cooling mechanism B3, cools battery 10, and returns to water-cooling mechanism B3. In other words, the coolant circulates between water-cooling mechanism B3 and battery 10. As shown in Fig. 3, electric vehicle system 100 also includes a detection device B4, a calculation device B5, and a storage device B6 that constitute a control mechanism for controlling the flow and temperature of air and coolant.

[0043] The air conditioner B1 is composed of an air conditioning unit 20, a chiller 21, a condenser 22, etc. on the air conditioning circuit 2. When the air conditioner B1 is set to on, outside air is taken into the air conditioner B1, and the air heated or cooled by the air conditioner B1 is supplied to the vehicle compartment 81. This cools or heats the vehicle compartment 81. Note that even when the air conditioner B1 is off, a certain amount of outside air is taken in.

[0044] The air-cooling mechanism B2 includes an air flow path 8 and a valve 821 that is an intake air control device that can adjust the amount of air passing through the battery 10. Air supplied from the air conditioner B1 into the vehicle interior 81 is supplied from the vehicle interior 81 to the air flow path 8 of the air-cooling mechanism B2. The air supplied to the air flow path 8 has its flow rate adjusted by the opening degree of the valve 821 of the air-cooling mechanism B2, and is introduced into the battery 10.

[0045] The air introduced into the battery 10 exchanges heat with the battery 10, thereby cooling the battery 10. The air that has exchanged heat with the battery 10 is then discharged outside the vehicle. In this way, the air inside the vehicle compartment, which is normally only discharged to the outside, can be effectively used to regulate the temperature of the battery 10, thereby making effective use of thermal energy and improving the driving range of the electric vehicle.

[0046] The water-cooling mechanism B3 includes a cooling water passage 1, and a cooling water control device including a heater 11, a chiller 21, an ePT unit 30, a radiator 40, first and second valves 61 and 62, and first and second pumps 71 and 72. The water-cooling mechanism B3 adjusts the temperature and flow rate of the cooling water flowing through the cooling water passage 1 and supplies the adjusted cooling water to the battery 10.

[0047] The coolant supplied to the battery 10 exchanges heat with the battery 10, thereby cooling the battery 10. The coolant that has exchanged heat with the battery 10 returns to the water-cooling mechanism B3, where the temperature and flow rate are adjusted.

[0048] The detection device B4 is a variety of sensors, and includes a temperature detection unit B51 and a pressure detection unit B52. The temperature detection unit B51 detects the temperature of the battery 10, the temperature of the cooling water in the cooling water passage 1 passing through the battery 10, the air temperature in the passenger compartment 81, etc., and transmits these to the controller 50 (computing device B5). The pressure detection unit B52 detects the pressure in the passenger compartment 80 and the pressure of the battery 10, and transmits these to the controller 50 (computing device B5).

[0049] The arithmetic device B5 and the storage device B6 are included in the controller 50. The arithmetic device B5 acquires various types of temperature information and pressure information detected by the detection device B4 and executes various processes. The storage device B6 stores programs and the like for executing each process, and the arithmetic device B5 executes various processes by appropriately referencing the programs stored in the storage device B6.

[0050] The arithmetic unit B5 controls the air conditioning unit B1 so that the temperature in the vehicle compartment 81 is maintained at a desired temperature based on the air temperature in the vehicle compartment 81, the set temperature of the air conditioning, etc. The arithmetic unit B5 also controls the water-cooling mechanism B3 so that the temperature of the battery 10 is maintained at an appropriate temperature based on the temperature of the battery 10, the temperature of the coolant in the cooling water passage 1 passing through the battery 10, etc. The arithmetic unit B5 also controls the air-cooling mechanism B2 (the opening degree of the valve 821) so that the temperature of the battery 10 is maintained at an appropriate temperature and temperature unevenness in the battery 10 is suppressed based on the temperature of the battery 10, the temperature of the air in the air passage 8 passing through the battery 10, the humidity in the air passage 8, the pressure in the vehicle compartment 81, the pressure in the battery 10, etc. Note that because air from the vehicle compartment 81 flows through the air passage 8, the air temperature and air humidity in the vehicle compartment 81 can be considered to be the temperature of the air in the air passage 8 passing through the battery 10 and the humidity in the air passage 8.

[0051] In this way, the controller 50 (arithmetic device B5) executes, as battery temperature regulation control, water-cooling control for cooling the battery 10 using coolant and air-cooling control for cooling the battery 10 using air.

[0052] FIG. 4 is a control block diagram of the water-cooling control, and FIG. 5 is a control block diagram of the air-cooling control.

[0053] As shown in FIG. 4 , in the water-cooling control, a comparator B101 compares the maximum temperature (hereinafter referred to as the maximum battery temperature) among the temperatures detected by the multiple temperature sensors in the battery 10 with a predetermined value (threshold value) X. Here, the threshold value X is set to a temperature at which the battery 10 needs to be cooled, for example, a temperature at which the energy efficiency of the battery 10 is optimized, and can be determined in advance through experiments, etc. If the maximum battery temperature is greater than the threshold value X, the water-cooling mechanism B3 is controlled to cool the battery 10 with the coolant flowing through the cooling water passage 1, thereby performing water-cooling of the battery 10. This improves the energy efficiency of the battery 10. On the other hand, if the maximum battery temperature is equal to or less than the threshold value X, the water-cooling mechanism B3 does not cool the battery 10 (water-cooling).

[0054] As described above, when the maximum battery temperature is greater than the threshold value X, water cooling of the battery 10 is performed.

[0055] On the other hand, as shown in Figure 5, the air cooling control includes a cooling judgment that determines whether or not cooling of the battery 10 is necessary and possible, a temperature unevenness suppression judgment that determines whether or not suppression of temperature unevenness of the battery 10 is necessary and possible, a dew point management control that prevents condensation in the battery 10, and a backflow prevention control that prevents backflow of air.

[0056] In the cooling determination, a comparator B102 compares the temperature of the upper portion of the battery 10 (hereinafter also referred to as the upper battery temperature) with a predetermined threshold Y. The threshold Y here is set to a temperature at which the battery 10 needs to be cooled, for example, a temperature at which the energy efficiency of the battery 10 is optimized, or a temperature slightly higher than that, and can be determined in advance through experiments, etc. In cases where the temperature of the battery 10 is not sufficiently cooled by water cooling control alone, the upper battery temperature becomes higher than the threshold Y. In this way, by performing cooling of the battery 10 using the air-cooling mechanism B2 when water cooling control alone is insufficient, the temperature of the battery 10 can be cooled to a desired temperature. That is, the comparator B102 compares the upper battery temperature with the threshold Y to determine whether the battery 10 needs to be cooled. The comparison result of the comparator B102 is input to a determination unit B104.

[0057] Next, comparator B103 compares the air temperature inside the vehicle compartment 81 (hereinafter also referred to as the vehicle compartment air temperature) with the temperature at the top of the battery. If the vehicle compartment air temperature is equal to or higher than the temperature at the top of the battery, the battery 10 cannot be cooled even if the air inside the vehicle compartment 81 is introduced into the battery 10. Therefore, comparator B103 compares the vehicle compartment air temperature with the temperature at the top of the battery to determine whether the battery 10 can be cooled by introducing the air from the vehicle compartment 81. The comparison result of comparator B103 is input to determination unit B104.

[0058] The determination unit B104 determines whether cooling of the battery 10 is both necessary and possible based on the comparison results of the comparators B102 and B103. Specifically, it determines whether the upper battery temperature is greater than a predetermined threshold Y and the vehicle interior temperature is lower than the upper battery temperature. If the upper battery temperature is greater than the predetermined threshold Y and the vehicle interior temperature is lower than the upper battery temperature, it can be determined that cooling of the battery 10 is both necessary and possible. The determination result of the determination unit B104 is input to the determination unit B111. Hereinafter, the condition in which the upper battery temperature is greater than the predetermined threshold Y and the vehicle interior temperature is lower than the upper battery temperature will be referred to as the "cooling requirement."

[0059] In the temperature unevenness suppression determination, first, a comparator B105 compares the temperature difference between the upper and lower temperatures of the battery 10 (hereinafter also referred to as the upper / lower battery temperature difference) with a predetermined threshold Z. The threshold Z here is set to a value that reduces the energy efficiency of the battery 10 or causes deterioration of the battery 10 due to the upper / lower battery temperature difference (temperature unevenness), and can be determined in advance through experiments, etc. If the upper / lower battery temperature difference is greater than the threshold Z, air-cooling control is executed to suppress the temperature unevenness of the battery 10, thereby improving the energy efficiency of the battery 10 and suppressing deterioration of the battery 10. That is, the comparator B105 compares the upper / lower battery temperature difference with the threshold Z to determine whether or not temperature unevenness suppression of the battery 10 is required. The comparison result of the comparator B105 is input to a determination unit B110.

[0060] Next, comparator B106 compares the upper temperature of battery 10 with the lower temperature of battery 10 (hereinafter also referred to as lower battery temperature). If the upper battery temperature is lower than the lower battery temperature, the upper part of battery 10 needs to be heated in order to suppress temperature unevenness in battery 10. On the other hand, if the upper battery temperature is higher than the lower battery temperature, the upper part of battery 10 needs to be cooled in order to suppress temperature unevenness in battery 10. Therefore, comparator B106 compares the upper battery temperature with the lower battery temperature to determine whether the upper part of battery 10 needs to be heated or cooled in order to suppress temperature unevenness in battery 10. The comparison result of comparator B106 is input to determination unit B109.

[0061] Comparators B107 and B108 compare the vehicle interior air temperature with the temperature at the top of the battery. Comparator B107 determines whether the vehicle interior air temperature is higher than the temperature at the top of the battery, and comparator B108 determines whether the vehicle interior air temperature is lower than the temperature at the top of the battery. The comparison results of comparators B107 and B108 are input to a determination unit B109.

[0062] The determination unit B109 determines which comparison result from comparator B107 or comparator B108 to adopt based on the comparison result from comparator B106. That is, if comparator B106 determines that the upper battery temperature is lower than the lower battery temperature, it adopts the comparison result from comparator B107, and if the upper battery temperature is higher than the lower battery temperature, it adopts the comparison result from comparator B108. The adopted comparison result from comparator B107 or comparator B108 is input to determination unit B110. Note that if the upper and lower battery temperatures are the same, either the comparison result from comparator B107 or comparator B108 may be adopted.

[0063] The determination unit B110 determines whether temperature unevenness suppression is necessary and possible based on the comparison results of the comparator B105 and the comparator B107 or B108 used in the determination unit B109. Specifically, when the temperature of the upper part of the battery 10 is lower than the temperature of the lower part of the battery and the comparison result of the comparator B107 is used, it is determined whether the temperature difference between the upper and lower parts of the battery is greater than the threshold Z and whether the passenger compartment air temperature is higher than the upper part of the battery. When the temperature difference between the upper and lower parts of the battery is equal to or less than the threshold Z, the need for temperature unevenness suppression is low. Furthermore, when the temperature of the upper part of the battery 10 is lower than the temperature of the lower part of the battery, the upper part of the battery 10 needs to be heated to suppress temperature unevenness. However, if the passenger compartment air temperature is not higher than the upper part of the battery, the upper part of the battery 10 cannot be heated even if air from the passenger compartment 81 is supplied to the upper part of the battery 10. Therefore, when the temperature difference between the upper and lower parts of the battery is greater than the threshold Z and the passenger compartment air temperature is higher than the upper part of the battery, it can be determined that temperature unevenness suppression is necessary and possible. On the other hand, if the upper battery temperature is higher than the lower battery temperature and the comparison result of comparator B108 is used, it is determined whether the temperature difference between the upper and lower battery sections is greater than threshold Z and whether the cabin air temperature is lower than the upper battery temperature. As described above, if the temperature difference between the upper and lower battery sections is equal to or less than threshold Z, there is little need for temperature unevenness suppression. Furthermore, if the upper battery temperature is higher than the lower battery temperature, the upper section of battery 10 needs to be cooled to suppress temperature unevenness. However, if the cabin air temperature is not lower than the upper battery temperature, supplying air from the cabin 81 to the upper section of battery 10 will not cool the upper section of battery 10. Therefore, if the temperature difference between the upper and lower battery sections is greater than threshold Z and the cabin air temperature is lower than the upper battery temperature, it can be determined that temperature unevenness suppression is both necessary and possible. Note that if the upper and lower battery temperatures are the same, the temperature difference between the upper and lower battery sections is equal to or less than threshold Z, and therefore it can be determined that temperature unevenness control is not necessary. The determination result of determination unit B110 is input to determination unit B111.Hereinafter, the "temperature unevenness suppression requirement" refers to the condition that the upper temperature of the battery 10 is lower than the lower temperature, the temperature difference between the upper and lower parts of the battery is greater than the threshold Z, and the air temperature inside the vehicle cabin is higher than the upper temperature of the battery, or the condition that the upper temperature of the battery 10 is higher than the lower temperature, the temperature difference between the upper and lower parts of the battery is greater than the threshold Z, and the air temperature inside the vehicle cabin is lower than the upper temperature of the battery.

[0064] The determination unit B111 determines whether air cooling (cooling of the battery 10 by the air-cooling mechanism B2) is necessary based on the results of the cooling determination and the temperature unevenness suppression determination. Specifically, it determines whether either the cooling requirement or the temperature unevenness suppression requirement is met. If either the cooling requirement or the temperature unevenness suppression requirement is met, it can be determined that it is necessary to supply air from inside the vehicle compartment 81 to the upper part of the battery 10 to cool (or warm) the battery 10. The determination result of the determination unit B111 is input to the determination unit 115.

[0065] In the dew point management control, a dew point estimation unit B112 estimates the dew point temperature in the air flow path 8. The dew point temperature is estimated based on the air temperature (vehicle interior air temperature) and air humidity (hereinafter referred to as vehicle interior air humidity) in the vehicle interior 81, for example, by referring to a map of the vehicle interior air temperature, the vehicle interior air humidity, and the dew point temperature. The estimated dew point temperature in the air flow path 8 is input to a comparator B113.

[0066] The comparator B113 compares the dew point temperature in the air flow path 8 estimated by the dew point temperature estimation unit B112 with the minimum temperature (hereinafter referred to as the minimum pack temperature) among the temperatures detected by multiple temperature sensors in the battery pack (battery) 10. If the minimum pack temperature is equal to or lower than the dew point temperature in the air flow path 8, condensation may occur in the battery 10, which may cause a short circuit or the like. That is, the comparator B113 compares the dew point temperature in the air flow path 8 with the minimum pack temperature to determine whether condensation will occur even if air from the passenger compartment 81 is supplied to the upper part of the battery 10. The comparison result of the comparator B113 is input to the determination unit B115.

[0067] In the backflow prevention control, a comparator B114 compares the pressure inside the vehicle compartment 81 (hereinafter referred to as vehicle compartment pressure) with the pressure inside the battery pack (battery) 10 (hereinafter referred to as pack pressure). If the vehicle compartment pressure is lower than the pack pressure, there is a risk of air flowing back from the battery pack 10 into the vehicle compartment 81. That is, the comparator B114 compares the pressure inside the vehicle compartment with the pressure inside the pack to determine whether air will flow back from the battery pack 10 into the vehicle compartment 81 even if the valve 821 in the air flow path 8 is opened. The comparison result of the comparator B114 is input to a determination unit B115.

[0068] The determination unit B115 ultimately determines whether or not to perform air cooling of the battery 10 based on the necessity of air cooling of the battery 10 (the determination result of the determination unit B111), the risk of condensation (the comparison result of the comparator B113), and the risk of air backflow (the comparison result of the comparator B114). Specifically, if either the cooling requirement or the temperature variation suppression requirement is met, the dew point temperature in the air flow path 8 is lower than the minimum temperature in the pack, and the passenger compartment pressure is equal to or higher than the pressure in the pack, air cooling of the battery 10 is performed ("1" is selected in FIG. 5). On the other hand, if neither the cooling requirement nor the temperature variation suppression requirement is met, the dew point temperature in the air flow path 8 is lower than the minimum temperature in the pack, or the passenger compartment pressure is equal to or higher than the pressure in the pack, air cooling of the battery 10 is not performed ("0" is selected in FIG. 5).

[0069] As described above, when either the cooling requirements or the temperature unevenness suppression requirements are met, and the dew point temperature in the air flow path 8 is lower than the minimum temperature inside the pack, and the pressure inside the vehicle cabin is equal to or higher than the pressure inside the pack, air cooling of the battery 10 is performed.

[0070] 6 and 7 are flowcharts of battery temperature adjustment control, with FIG. 6 being a flowchart of water-cooling control and FIG. 7 being a flowchart of air-cooling control. All of the following controls are repeatedly executed by the controller 50. The controller 50 also acquires detected values ​​from various sensors as needed. The controller 50 also estimates and acquires the dew-point temperature in the air flow path 8 as needed.

[0071] When the vehicle system is started, for example, by turning on the ignition switch, the controller 50 starts the battery temperature regulation control.

[0072] First, the flow of water cooling control will be described with reference to FIG.

[0073] In step S101, the controller 50 determines whether the maximum battery temperature is greater than the threshold value X. If the maximum battery temperature is greater than the threshold value X, the controller 50 executes the process of step S102. On the other hand, if the maximum battery temperature is equal to or less than the threshold value X, the controller 50 does not perform water cooling of the battery 10, ends the water cooling control, and executes the process of step S101 again.

[0074] If the maximum battery temperature is greater than the threshold value X in step S101, the controller 50 performs water cooling of the battery 10 in step S102. As a result, the battery 10 is cooled.

[0075] As described above, the controller 50 continues the water-cooling control while the maximum battery temperature is greater than the threshold value X.

[0076] Next, the flow of air cooling control will be described with reference to FIG.

[0077] Step S201 is a step for executing backflow prevention control. In step S201, the controller 50 determines whether the pressure inside the vehicle interior is equal to or higher than the pack pressure. If the pressure inside the vehicle interior is lower than the pack pressure, opening the valve 821 to air-cool the battery 10 may cause air in the air flow path 8 to flow back from the battery 10 into the vehicle interior 81. Therefore, if the pressure inside the vehicle interior is lower than the pack pressure, the controller 50 does not air-cool the battery 10, ends the air-cooling control, and executes the process from step S201 again. On the other hand, if the pressure inside the vehicle interior is equal to or higher than the pack pressure, the controller 50 executes the process of step S202.

[0078] Step S202 is a step for executing dew point management control. In step S202, the controller 50 determines whether the dew point temperature in the air flow path 8 is lower than the minimum temperature in the pack. If the minimum temperature in the pack is equal to or lower than the dew point temperature in the air flow path 8, condensation may occur in the battery 10, which may cause a short circuit or the like. Therefore, if the minimum temperature in the pack is equal to or lower than the dew point temperature in the air flow path 8, the controller 50 does not perform air cooling of the battery 10, terminates the air cooling control, and executes the processing from step S201 again. On the other hand, if the dew point temperature in the air flow path 8 is lower than the minimum temperature in the pack, the controller 50 executes the processing from step S203. As described above, the dew point temperature in the air flow path 8 is estimated based on the vehicle interior air temperature and interior air humidity by referring to a map of the vehicle interior air temperature, the vehicle interior air humidity, and the dew point temperature, but this is not limited to this.

[0079] Steps S203 to S207 are steps for executing a cooling determination and a temperature nonuniformity suppression determination.

[0080] In step S203, the controller 50 determines whether the temperature at the upper part of the battery is greater than a threshold Y. That is, it determines whether the temperature of the battery 10 needs to be regulated (cooled). If the temperature at the upper part of the battery is greater than the threshold Y, that is, if the battery 10 needs to be cooled, the controller 50 executes the process of step S206. On the other hand, if the temperature at the upper part of the battery is equal to or less than the threshold Y, the controller 50 executes the process of step S204.

[0081] If the temperature at the top of the battery is equal to or lower than threshold Y, the controller 50 determines in step S204 whether the temperature difference between the upper and lower parts of the battery is greater than threshold Z. That is, it determines whether it is necessary to suppress temperature unevenness in the battery 10. If the temperature difference between the upper and lower parts of the battery is equal to or lower than threshold Z in step S204, there is no need to cool the battery 10 or to suppress temperature unevenness in the battery 10, so the controller 50 does not perform air-cooling of the battery 10, ends the air-cooling control, and executes the processing from step S201 again. On the other hand, if the temperature difference between the upper and lower parts of the battery is greater than threshold Z, that is, if it is necessary to suppress temperature unevenness in the battery 10, the controller 50 executes the processing of step S205.

[0082] In step S205, the controller 50 determines whether the upper battery temperature is higher than the lower battery temperature. That is, it determines whether the upper part of the battery 10 needs to be heated or cooled in order to suppress temperature unevenness in the battery 10. In step S205, if the upper battery temperature is higher than the lower battery temperature, that is, if the upper part of the battery 10 needs to be cooled, the controller 50 executes the process of step S206. On the other hand, if the upper battery temperature is lower than the lower battery temperature, that is, if the upper part of the battery 10 needs to be heated, the controller 50 executes the process of step S207.

[0083] If the upper battery temperature is greater than the threshold Y in step S203, or if the upper battery temperature is higher than the lower battery temperature in step S205, the controller 50 determines in step S206 whether the upper battery temperature is higher than the vehicle interior air temperature. If the upper battery temperature is equal to or lower than the vehicle interior temperature, the battery 10 cannot be cooled from above even if air from the vehicle interior 81 is supplied to the upper part of the battery 10. Therefore, the controller 50 does not perform air-cooling of the battery 10, ends the air-cooling control, and executes the process from step S201 again.

[0084] On the other hand, if the upper battery temperature is higher than the lower battery temperature in step S206, the controller 50 executes the process of step S208. In step S208, the controller 50 opens the valve 821 to supply air from the vehicle interior 81 to the battery 10, thereby cooling the battery 10.

[0085] If the upper battery temperature is lower than the lower battery temperature in step S205, i.e., if it is necessary to heat the upper part of the battery 10 to suppress temperature unevenness, the controller 50 determines in step S207 whether the upper battery temperature is lower than the vehicle cabin air temperature. If the upper battery temperature is equal to or higher than the vehicle cabin air temperature, the battery 10 cannot be cooled from above even if air from the vehicle cabin 81 is supplied to the upper part of the battery 10. Therefore, in this case, the controller 50 does not supply air from the vehicle cabin 81 to the battery 10, ends the air-cooling control, and executes the process from step S201 again.

[0086] On the other hand, if the upper battery temperature is lower than the lower battery temperature in step S207, the controller 50 executes the process of step S208, i.e., opens the valve 821 to supply air from the vehicle interior 81 to the battery 10, thereby warming up the upper part of the battery 10.

[0087] The order of execution of step S201 (backflow prevention control), step S202 (dew point management control), and steps S203 to S207 (cooling determination and temperature nonuniformity suppression determination) may be interchanged.

[0088] According to the electric vehicle of the above embodiment, the following effects can be obtained.

[0089] The electric vehicle of this embodiment includes a cooling water passage 1 through which coolant flows to exchange heat with the battery 10, and an air passage 8 through which air flows to exchange heat with the battery 10. The cooling water passage 1 passes below the battery 10, and the air passage 8 passes above the battery 10. As a result, the temperature of the battery 10 is regulated by the coolant flowing through the cooling water passage 1 at the bottom of the battery 10, and the temperature of the battery 10 is regulated by the air flowing through the air passage 8 at the top of the battery 10. In other words, because the temperature of the battery 10 is regulated at the top and bottom of the battery 10, the temperature distribution between the top and bottom of the battery 10 is reduced. Therefore, temperature unevenness in the battery 10 can be reduced, and a decrease in the energy efficiency and charging performance of the battery 10, as well as deterioration of the battery 10, can be suppressed.

[0090] Furthermore, since the temperature of the battery 10 is regulated at the upper and lower parts of the battery 10, the battery 10 can be cooled (or warmed) efficiently.

[0091] In the electric vehicle of this embodiment, the air flow path 8 is connected to the interior of the vehicle compartment 81 of the electric vehicle, and the air flowing through the air flow path 8 is air from the interior of the vehicle compartment 81. That is, the air inside the vehicle compartment 81 is used to regulate the temperature of the battery 10. In this way, the air inside the vehicle compartment that is normally just discharged to the outside is effectively used to regulate the temperature of the battery 10, making it possible to effectively utilize thermal energy and improving the cruising range of the electric vehicle.

[0092] The electric vehicle of this embodiment is provided with an exhaust passage 9 that is connected to the air flow path 8 and that discharges air that has passed from inside the vehicle compartment 81 and passed through the battery 10 to the outside of the vehicle. This allows the air from inside the vehicle compartment 81 that has exchanged heat with the battery 10 to be returned to the vehicle compartment 81, preventing the temperature inside the vehicle compartment 81 from becoming unintended.

[0093] In the electric vehicle of this embodiment, the air flow path 8 has a desiccant 822 in the conduction path 82 between the vehicle interior 81 and the battery 10. This reduces the humidity of the air introduced from the vehicle interior 81 to the battery 10, preventing condensation and short circuits in the battery 10.

[0094] The electric vehicle of this embodiment includes a controller 50 that controls a coolant control device that can adjust the temperature and flow rate of coolant passing through a lower portion of the battery 10 and an intake air control device that can adjust the amount of air passing through an upper portion of the battery 10. When the maximum temperature inside the battery 10 is greater than a threshold X (a predetermined value), the controller 50 controls the coolant control device to perform heat exchange between the battery 10 and the coolant to cool the battery 10. When the temperature difference between the upper and lower portions of the battery 10 (the temperature difference between the upper and lower portions of the battery) is greater than a threshold Y (a predetermined value), the controller 50 controls the intake air control device to perform heat exchange between the battery 10 and the air to cool the battery 10. In this way, when the temperature difference between the upper and lower portions of the battery is greater than the threshold Y, heat exchange between the battery 10 and the air is performed from the upper portion of the battery 10, which is opposite the lower portion of the battery 10 through which the coolant passes. This can further reduce temperature unevenness in the battery 10.

[0095] The electric vehicle of this embodiment includes a valve 821 that controls the amount of air introduced from the vehicle interior 81 into the battery 10, and the valve 821 is provided on the conduction path 82 between the vehicle interior 81 and the battery 10 in the air flow path 8. Therefore, the temperature of the battery 10 can be appropriately controlled by opening the valve 821 only when it is necessary to perform heat exchange between the battery 10 and the air (air-cooling of the battery 10) from above the battery 10 and air cooling of the battery 10 is possible. Furthermore, when there is a risk of air flowing back from the battery 10 into the vehicle interior 81, the valve 821 can be closed to prevent unintended air backflow.

[0096] In the electric vehicle of this embodiment, the controller 50 controls the opening degree of the valve 821 based on the temperature of the air in the air flow path 8, the humidity in the air flow path 8, the temperature of the battery 10, and the pressure in the vehicle compartment 81 and the pressure in the battery 10. This allows the valve 821 to be opened only when air cooling of the battery 10 is necessary and possible, thereby enabling appropriate temperature control of the battery 10. Furthermore, when there is a risk of air flowing back from the battery 10 into the vehicle compartment 81, such as when the pressure in the vehicle compartment 81 is higher than the pressure in the battery 10, the valve 821 can be closed to prevent unintended air flow back.

[0097] In this embodiment, the cooling water passage 1 passes through the bottom of the battery 10, and the air passage 8 passes through the top of the battery 10, but this is not necessarily limited to this. For example, the cooling water passage 1 may pass through the top of the battery 10, and the air passage 8 may pass through the bottom of the battery 10.

[0098] In addition, in this embodiment, the air flow path 8 (temperature adjustment passage 83) above the battery 10 is a dedicated air path provided above the battery 10, but this is not necessarily limited to this. For example, a dedicated air path may not be provided above the battery 10, and air that exchanges heat with the battery 10 may be blown from above the battery 10. In this case, the air flow path 8 (temperature adjustment passage 83) above the battery 10 is formed by the flow of air.

[0099] Furthermore, although the present embodiment has been described as basically a situation in which the battery 10 is cooled, the configuration including the air flow path 8 passing through the upper part of the battery 10 and the cooling water path 1 passing through the lower part can also be used when warming up the battery 10. When used for warming up the battery 10, it is possible to suppress temperature unevenness in the battery 10 and improve the warm-up efficiency.

[0100] In addition, as in the present embodiment, it is preferable to use the air inside the vehicle compartment 81 as the air that exchanges heat with the battery 10 above the battery 10, but this is not necessarily limited to this. For example, a configuration may be adopted in which air that has been temperature-adjusted separately from the air inside the vehicle compartment 81 is used to exchange heat with the battery 10 above the battery 10.

[0101] Furthermore, as in this embodiment, it is preferable that the desiccant 822 is provided in the air flow path 8, but this is not necessarily limited to this, and the desiccant 822 does not necessarily have to be provided in the air flow path 8.

[0102] Although the embodiments of the present invention have been described above, the above embodiments merely illustrate some of the application examples of the present invention, and it is not intended that the technical scope of the present invention be limited to the specific configurations of the above embodiments.

Claims

1. An electric vehicle comprising: a battery; a cooling water passage through which coolant flows for heat exchange with the battery; and an air flow passage through which air flows for heat exchange with the battery, wherein the cooling water passage passes through one of the upper and lower parts of the battery, and the air flow passage passes through the other of the upper and lower parts of the battery.

2. An electric vehicle according to claim 1, wherein the air flow path is connected to an interior of the vehicle compartment, and the air flowing through the air flow path is air from the interior of the vehicle compartment.

3. An electric vehicle according to claim 2, further comprising an exhaust passage connected to the air flow path and for discharging air that has passed through the battery from the passenger compartment to the outside of the vehicle.

4. An electric vehicle according to claim 2, wherein the air flow path has a desiccant in a conductive path between the vehicle compartment and the battery.

5. An electric vehicle as defined in any one of claims 1 to 4, further comprising: a coolant control device capable of adjusting the temperature and flow rate of the coolant passing through the battery; an intake air control device capable of adjusting the amount of air passing through the battery; and a controller that controls the coolant control device and the intake air control device, wherein the controller controls the coolant control device to perform heat exchange between the battery and the coolant to cool the battery when the maximum temperature inside the battery is greater than a predetermined value, and controls the intake air control device to perform heat exchange between the battery and the air to cool the battery when the temperature difference between the upper part of the battery and the lower part of the battery is greater than a predetermined value.

6. An electric vehicle as claimed in claim 5, wherein the air flow path is connected to the interior of the vehicle cabin, and the air flowing through the air flow path is air from the interior of the vehicle cabin, and the intake air control device is a valve that controls the amount of air introduced from the interior of the vehicle cabin to the battery, and the valve is provided on a conductive path in the air flow path between the interior of the vehicle cabin and the battery.

7. An electric vehicle according to claim 6, wherein the controller controls the opening of the valve based on the temperature of the air in the air flow path, the humidity in the air flow path, the temperature of the battery, the pressure in the vehicle compartment, and the pressure in the battery.

8. A control method for an electric vehicle having a battery, a cooling water passage through which coolant that exchanges heat with the battery flows and passes through one of the upper and lower parts of the battery, and an air flow passage through which air that exchanges heat with the battery flows and passes through the other of the upper and lower parts of the battery, wherein the air flow passage is connected to a passenger compartment of the electric vehicle, and the air flowing through the air flow passage is air from the passenger compartment, and when a maximum temperature inside the battery is greater than a predetermined value, heat exchange is performed between the battery and the cooling water to cool the battery, and when a temperature difference between the temperature of the upper part of the battery and the temperature of the lower part of the battery is greater than a predetermined value, heat exchange is performed between the battery and the air to cool the battery.

9. A control method for an electric vehicle according to claim 8, comprising controlling the amount of air introduced from the vehicle interior into the battery based on the temperature of the air in the air flow path, the humidity in the air flow path, the temperature of the battery, and the pressure in the vehicle interior and the pressure in the battery.

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