Battery warming method and battery warming device

Abstract

An aspect of the present invention is a battery heating method for heating a battery in an electric vehicle when the temperature of the battery, which supplies power to an electric powertrain, is lower than a prescribed temperature determined in advance, or when it is estimated that the temperature of the battery will become lower than the prescribed temperature. This battery heating method has, as heating modes for heating the battery, a first mode for heating the battery by using heat generated by the battery itself, and a second mode for heating the battery by using heat generated by the electric powertrain. The first mode and the second mode are switched until the temperature of the battery reaches the prescribed temperature.

Description

[Technical Field]

[0001] This invention relates to a battery warming method and a battery warming device. Regarding. [Background technology]

[0002] JP5849917B discloses a battery temperature rise control device that raises the temperature of an on-board battery by repeatedly and alternately performing discharge control, which supplies d-axis current to the motor, and charge control, which returns the energy stored in the motor windings to the battery. [Overview of the project]

[0003] Battery performance deteriorates in low-temperature environments. Therefore, in electric vehicles powered by battery electricity, it is desirable to maintain battery performance by warming up the battery when its temperature drops, or when its temperature is expected to drop.

[0004] While it is common to use heaters such as PTC (Positive Temperature Coefficient) heaters to warm up batteries, adding a heater solely for the purpose of warming up the battery presents problems such as increased costs. For this reason, in recent years, methods have been proposed to warm up batteries without adding a heater, such as generating heat in the battery itself by repeatedly discharging and charging, or transporting heat generated by an electric motor to warm up the battery.

[0005] However, in a warm-up method that generates heat by repeatedly charging and discharging the battery, the current that can flow during charging and discharging is limited to a small value in order to suppress electrodeposition during charging. In other words, this warm-up method generates little heat and takes a long time to warm up the battery.

[0006] On the other hand, in warm-up methods that use heat generated by the electric motor, a considerable amount of heat is dissipated during the transport process. Also, when the electric motor is cold, it needs to be warmed up before the battery. In other words, warm-up methods that use heat generated by the electric motor can be energy inefficient.

[0007] The present invention aims to provide a battery warming method and a battery warming device for electric vehicles that can warm up the battery in an energy-efficient manner and in a short amount of time.

[0008] One aspect of the present invention is a battery warming method for an electric vehicle, which warms up a battery when the temperature of the battery supplying power to the electric powertrain is below a predetermined temperature, or when the battery temperature is expected to fall below a predetermined temperature. This battery warming method has two warming modes: a first mode in which the battery is warmed by the heat generated by the battery itself, and a second mode in which the battery is warmed by the heat generated by the electric powertrain. After warming up the engine, The system switches between Mode 1 and Mode 2 until the battery temperature reaches a predetermined temperature. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a block diagram showing the schematic configuration of an electric vehicle. [Figure 2] Figure 2 is a schematic graph showing the changes in d-axis voltage, d-axis current, and battery current in the first mode. [Figure 3] Figure 3 is a schematic graph showing the changes in d-axis voltage, d-axis current, and battery current in the second mode. [Figure 4] Figure 4 is a block diagram showing the configuration of the warm-up control unit. [Figure 5] Figure 5 is a schematic graph showing the changes in heat quantity and efficiency for each mode after the start of warm-up. [Figure 6]Figure 6 is a graph showing the switching patterns of the warm-up mode when warm-up speed priority is set. [Figure 7] Figure 7 is a graph showing the switching patterns of the warm-up mode in the efficiency-prioritizing setting. [Figure 8] Figure 8 is a flowchart showing the switching of warm-up modes. [Figure 9] Figure 9 is a flowchart related to the flow path control of the heat exchange medium. [Figure 10] Figure 10 is a flowchart relating to flow path control in a modified example. [Figure 11] Figure 11 is a flowchart relating to flow path control in a modified example. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings.

[0011] Figure 1 is a block diagram showing the schematic configuration of the electric vehicle 100. As shown in Figure 1, the electric vehicle 100 is a vehicle such as an electric vehicle or hybrid vehicle that generates driving force using electricity supplied by a battery 10, and in addition to the battery 10, it includes an electric powertrain 11, a heat exchange system 12, a temperature control unit 13, and a controller 14, etc.

[0012] The battery 10 is a secondary battery, such as a lithium-ion battery, and is capable of discharge and recharge. When the electric vehicle 100 is running, the battery 10 supplies DC power to the electric powertrain 11. When the electric vehicle 100 is decelerating, the battery 10 is charged by power generated by the electric powertrain 11 through so-called regenerative control. Furthermore, if the electric powertrain 11 includes a power generation system, the battery 10 is charged by the power generated by that power generation system.

[0013] In this embodiment, in order to maintain performance, the temperature of the battery 10 (hereinafter referred to as battery temperature θ1) is kept within a predetermined temperature range (for example, θ) at least during use.min , bat ,

[0016] , max , min , , min , , min , min , , max ,

[0015] , min , , min ≦θ1≦θ max ) so that the battery 10 is warmed up or cooled down. The lower limit θ of the battery temperature θ1 min and the upper limit θ max are determined in advance by experiments, simulations, etc.

[0014] For example, when the electric vehicle 100 starts from a long - time stop state in a cold region where the environmental temperature is lower than the lower limit θ min , the battery temperature θ1, which is at a low temperature level similar to the environmental temperature, is warmed up so that it is not less than the lower limit θ min . Also, for example, when the electric vehicle 100 continues to park in a state where it can start in a cold region, etc., when the battery temperature θ1 becomes lower than the lower limit θ min , or when it is expected that the battery temperature θ1 will become lower than the lower limit θ min , the battery 10 is warmed up. That is, in the electric vehicle 100, when the battery temperature θ1 is lower than the predetermined temperature, which is the lower limit θ min , or when it is expected that the battery temperature θ1 will become lower than the lower limit θ min , the battery 10 is warmed up. The goal of the warm - up control of the battery 10 is to make the battery temperature θ1 reach the lower limit θ min or a higher temperature. That is, the lower limit θ min or a higher temperature is the predetermined temperature (target temperature) for the warm - up control. In this embodiment, the lower limit θ min is the target temperature.

[0015] Also, when the battery 10 is rapidly charged, etc., when the battery temperature θ1 becomes higher than the upper limit θ max , or when it is expected that the battery temperature θ1 will become higher than the upper limit θ max , the battery 10 is cooled down.

[0016] In addition, the current input and output by the battery 10 (hereinafter, the battery current I batThe current and voltage are measured by the current sensor 21 and the voltage sensor 22, respectively, and can be acquired at any time. The State of Charge (SOC), which represents the charge level of the battery 10, can be calculated at any time based on the voltage of the battery 10 (open circuit voltage, etc.). In addition, the battery temperature θ1 is measured by the temperature sensor 23 and can be acquired at any time.

[0017] The electric powertrain 11 (ePT) is an entire set of devices for generating driving force for the electric vehicle 100, and includes at least one rotating electric machine 25 and an inverter 26 for driving the rotating electric machine 25. The electric powertrain 11 may include a power generation system (not shown) for generating electricity to charge the battery 10. The power generation system is configured, for example, using an internal combustion engine and a generator.

[0018] The rotating electric machine 25 is either an electric motor or a generator. More specifically, the rotating electric machine 25 is an electric motor that generates driving force for the electric vehicle 100, or a generator included in a power generation system. The rotating electric machine 25 includes windings 27 in its stator, rotor, or stator and rotor. In this embodiment, the rotating electric machine 25 is a three-phase AC synchronous motor that generates driving force for the electric vehicle 100, and at least the stator has windings 27 for generating a rotating magnetic field. In this embodiment, the windings 27 of the rotating electric machine 25 are also used in the control of warming up the battery 10 (hereinafter referred to as battery 10 warm-up control).

[0019] The inverter 26 is connected to the battery 10. The inverter 26 drives the rotating electric machine 25 using the DC power output by the battery 10. In this embodiment, the inverter 26 converts the DC power from the battery 10 into three-phase AC power by switching on and off a plurality of built-in switching elements and supplies it to the rotating electric machine 25, thereby generating torque in the rotating electric machine 25. This torque generates driving force for the electric vehicle 100. The inverter 26 also charges the battery 10 by inputting the power generated by the rotating electric machine 25 into the battery 10. In this embodiment, the inverter 26 converts the AC power generated by the rotating electric machine 25 into DC power by switching on and off the switching elements and inputs it to the battery 10. In addition, in this embodiment, the inverter 26 is also used for warming up the battery 10.

[0020] In addition, the electric vehicle 100 includes a temperature sensor 28 for measuring the temperature of the electric powertrain 11 (hereinafter referred to as ePT temperature θ2), and a sensor 29 for measuring the carrier frequency or switching frequency of the inverter 26 (hereinafter referred to as carrier frequency f2). Therefore, the ePT temperature θ2 and carrier frequency f2 can be acquired at any time as appropriate.

[0021] The heat exchange system 12 exchanges heat with the battery 10 and the electric powertrain 11, warming up or cooling the battery 10 and the electric powertrain 11 individually or simultaneously. In principle, the heat exchange system 12 is a cooling system that cools the electric powertrain 11 and the battery 10 when their temperature rises while the electric vehicle 100 is running or otherwise operating. In the warm-up control of the battery 10 in this embodiment, the heat exchange system 12 functions as a heat transport system that warms the battery 10 by transporting (transferring) the heat generated in the electric powertrain 11 to the battery 10. The medium used by the heat exchange system 12 for heat exchange with the battery 10 and the electric powertrain 11 (hereinafter referred to as the heat exchange medium) is, for example, water or other liquids or gases. Specifically, the heat exchange system 12 includes a first heat exchange section 31, a second heat exchange section 32, and a heat exchange medium cooling section 33.

[0022] The first heat exchange unit 31 is the part of the heat exchange system 12 that is thermally connected to the battery 10 and exchanges heat with the battery 10.

[0023] The first heat exchange unit 31 is connected to the heat exchange medium cooling unit 33 by a first flow path 34 that circulates the heat exchange medium between the heat exchange unit 31 and the heat exchange medium cooling unit 33. A valve (not shown) is provided in the first flow path 34. By opening this valve, the first heat exchange unit 31 is thermally connected to the heat exchange medium cooling unit 33, and by closing this valve, the connection between the first heat exchange unit 31 and the heat exchange medium cooling unit 33 is released.

[0024] Furthermore, the first heat exchange section 31 is connected to the second heat exchange section 32 by a second flow path 35 that circulates a heat exchange medium between the two sections. A valve (not shown) is provided in the second flow path 35. By opening this valve, the first heat exchange section 31 is thermally connected to the second heat exchange section 32, and by closing this valve, the connection between the first heat exchange section 31 and the second heat exchange section 32 is released.

[0025] The second heat exchange section 32 is the part of the heat exchange system 12 that is thermally connected to the electric powertrain 11 and exchanges heat with the electric powertrain 11.

[0026] As described above, the second heat exchange section 32 is connected to the first heat exchange section 31 by a second flow path 35, and is also connected to the heat exchange medium cooling section 33 by a third flow path 36 that circulates the heat exchange medium between the heat exchange section 32 and the heat exchange medium cooling section 33. A valve (not shown) is provided in the third flow path 36. By opening this valve, the second heat exchange section 32 is thermally connected to the heat exchange medium cooling section 33, and by closing this valve, the connection between the second heat exchange section 32 and the heat exchange medium cooling section 33 is released.

[0027] The heat exchange medium cooling unit 33 is a part of the heat exchange system 12 that cools the heat exchange medium, which carries the heat generated in the battery 10 and the electric powertrain 11, with outside air (or airflow when the electric vehicle 100 is running). The heat exchange medium cooling unit 33 is, for example, the radiator of the electric vehicle 100. The heat exchange medium cooling unit 33 is connected to the first heat exchange unit 31, the second heat exchange unit 32, or both, as needed, and cools the battery 10 and the electric powertrain 11 by cooling the heat exchange medium circulating between them. Therefore, when warming up the battery 10, the connection between the heat exchange medium cooling unit 33 and at least the first heat exchange unit 31 is disconnected. In this embodiment, for simplicity, when warming up the battery 10, the connection between the heat exchange medium cooling unit 33 and the first heat exchange unit 31, and the connection between the heat exchange medium cooling unit 33 and the second heat exchange unit 32 are both disconnected.

[0028] In addition, the heat exchange system 12 includes one or more pumps, compressors, or blowers (hereinafter referred to as "pumps") (not shown) for circulating the heat exchange medium to each part. Note that connection to each part of the heat exchange system 12 means opening the valves in the flow paths connecting them, operating the pumps to circulate the heat exchange medium, and thereby transporting heat between the parts.

[0029] The temperature control unit 13 opens and closes valves in the heat exchange system 12 according to instructions from the controller 14. The temperature control unit 13 also starts or stops the pumps in the heat exchange system 12 according to instructions from the controller 14. As a result, the temperature control unit 13 changes the state of the heat exchange system 12, warming up or cooling the battery 10 and the electric powertrain 11 individually or simultaneously.

[0030] The controller 14 is one or more computers that comprehensively control the operation of the electric vehicle 100, the operation of each component of the electric vehicle 100, and the operation of the electric vehicle 100 as a whole. Specifically, the controller 14 is programmed to control the electric powertrain 11 and control the driving of the electric vehicle 100. The controller 14 is also programmed to perform warm-up control of the battery 10 by controlling the electric powertrain 11. Therefore, the controller 14 constitutes a battery warm-up control device in the electric vehicle 100. In warm-up control of the battery 10, the controller 14 may also control the heat exchange system 12 via the temperature control unit 13.

[0031] Specifically, the controller 14 functions as, for example, a state detection unit 41, a rotating electric machine control unit 42, and a warm-up control unit 43.

[0032] The state detection unit 41 detects the operating state of the electric vehicle 100, or the operating state of each component of the electric vehicle 100. For example, the state detection unit 41 appropriately detects the battery temperature θ1 by acquiring the output signal of the temperature sensor 23. The state detection unit 41 also appropriately detects the ePT temperature θ2 by acquiring the output signal of the temperature sensor 28. Similarly, the state detection unit 41 appropriately detects the carrier frequency f2 of the inverter 26, the current and voltage input and output of the battery 10, the accelerator opening (accelerator operation amount) of the electric vehicle 100, the vehicle speed, and the rotational speed of the rotating electric machine 25. In addition to acquiring the above parameters using various sensors, the state detection unit 41 may also detect other parameters used by the rotating electric machine control unit 42 and the warm-up control unit 43 by calculating them using the acquired parameters. In this embodiment, the state detection unit 41 estimates the state of charge (SOC) of the battery 10 based on the output voltage of the battery 10. The parameters detected by the state detection unit 41 are used in various controls performed by the rotating electric machine control unit 42 and the warm-up control unit 43.

[0033] The rotating electric machine control unit 42 controls the drive of the rotating electric machine 25. For example, the rotating electric machine control unit 42 calculates target values ​​(command values) such as the rotational speed that the rotating electric machine 25 should reach or maintain, or the torque that the rotating electric machine 25 should generate, in response to a request from the electric vehicle 100. These target values ​​are calculated, for example, based on the rotational speed of the rotating electric machine 25 and the accelerator opening of the electric vehicle 100. The rotating electric machine control unit 42 also adjusts the voltage, current, etc., supplied to the rotating electric machine 25 by operating the inverter 26 based on these calculated target values. As a result, the rotating electric machine 25 maintains a rotational speed corresponding to the target value set in response to a request from the electric vehicle 100, or generates a torque corresponding to the target value set in response to a request from the electric vehicle 100.

[0034] Furthermore, in this embodiment, when performing warm-up control of the battery 10, the rotating electric machine control unit 42 may control the inverter 26 and the rotating electric machine 25 according to the instructions of the warm-up control unit 43. For example, the rotating electric machine control unit 42 supplies power to the inverter 26 and the rotating electric machine 25, or causes power to be input from the rotating electric machine 25 to the battery 10 via the inverter 26, in response to a request from the warm-up control unit 43. As a result, the rotating electric machine control unit 42 generates heat in the rotating electric machine 25 and the inverter 26, warming the electric powertrain 11. In this way, the heat generated in the electric powertrain 11, such as the rotating electric machine 25 and the inverter 26 (hereinafter referred to as "heat generated in the electric powertrain 11"), is transported to the battery 10 and used to warm up the battery 10.

[0035] The warm-up control unit 43 performs warm-up control of the battery 10. The warm-up control of the battery 10 performed by the warm-up control unit 43 has two modes (warm-up modes) which differ in the specific method of warming up the battery 10, as follows:

[0036] The first warm-up mode (hereinafter simply referred to as the first mode) is a warm-up mode in which the battery 10 is warmed up by the heat generated by the battery 10 itself. That is, in the first mode, the warm-up control unit 43 warms up the battery 10 by generating heat in the battery 10 itself. At this time, the amount of power stored in the battery 10 that is consumed is essentially only the amount that is converted into thermal energy in the battery 10, etc.

[0037] In this embodiment, in the first mode, the warm-up control unit 43 stores energy in the elements of the electric powertrain 11 by discharging the battery 10, and then charges the battery with the energy stored in those elements. The warm-up control unit 43 then repeats this discharge and charging process to increase the battery current I bat This causes the internal resistance R of the battery 10 to be generated. bat This causes the battery 10 itself to generate heat.

[0038] In this embodiment, the element that stores energy in the electric powertrain 11 is the winding 27 of the rotating electric machine 25. That is, the warm-up control unit 43 energizes the winding 27 with the battery 10, thereby storing energy in the winding 27 in proportion to its inductance. After that, the warm-up control unit 43 stops supplying power to the winding 27 and charges the battery 10 with the energy stored in the winding 27.

[0039] Furthermore, if the electric powertrain 11 includes inductors, capacitors, etc., that can be used for the above purposes in addition to the windings 27, the warm-up control unit 43 can store the energy discharged from the battery 10 in these elements instead of the windings 27 in the first mode. Also, if the electric powertrain 11 has multiple elements that can be used for the above purposes, the warm-up control unit 43 can store the energy discharged from the battery 10 in these multiple elements.

[0040] Furthermore, in the first mode, the current supplied by the warm-up control unit 43 to the rotating electric machine 25 is the so-called d-axis current I dThis is the d-axis current I of the current flowing through the rotating electric machine 25. d This is the current component that generates the magnetic field, and the q-axis current I q (Not shown) is the current component for generating torque. Therefore, the warm-up control unit 43 applies a voltage to the d-axis of the rotating electric machine 25 and selectively supplies the d-axis current I to the rotating electric machine 25. d By flowing or increasing the current, energy can be stored in the winding 27 without changing the rotational state of the rotating electric machine 25.

[0041] Figure 2 shows the (A)d-axis voltage V in the first mode. d , (B) d-axis current I d , and (C) Battery current I bat This graph schematically shows the trend of [the voltage]. d-axis: voltage V d This represents the d-axis component of the voltage input and output by the rotating electric machine 25. Figure 2 shows an example where the rotating electric machine 25 is stopped rotating.

[0042] In the first mode, the d-axis voltage V in a predetermined direction (positive direction) d A voltage is periodically applied. That is, as shown in Figure 2(A), the rotating electric machine 25 has a d-axis voltage V d This is applied periodically. In this way, as the battery 10 repeatedly discharges and charges, the winding 27 repeatedly stores and releases energy, so as shown in Figure 2(B), the d-axis current I of the rotating electric machine 25 d This also changes periodically. As a result, as shown in Figure 2(C), the battery 10 repeatedly discharges and charges. Here, the positive battery current I bat This represents the discharge of battery 10, and the negative battery current I bat This indicates that battery 10 is being charged.

[0043] Furthermore, the d-axis current I flowing through the rotating electric machine 25 in the second mode... d When it is necessary to distinguish it from the above, the d-axis current I flowing through the rotating electric machine 25 in the first mode d The d-axis current I in the first mode d1 That's what they say.

[0044] Furthermore, in the first mode, the discharge and charge frequency (hereinafter referred to as the discharge / charge frequency f1) is relatively large, and its period (discharge / charge period 1 / f1) is short. In other words, compared to the case where the rotating electric machine 25 is driven to generate torque, the d-axis current I in the first mode is d1 This is a so-called high-frequency current. The charging / discharging frequency f1 is, for example, the d-axis current I used to drive the rotating electric machine 25 to generate torque. d This frequency band is as high as the superimposed high-frequency noise current (so-called ripple current). Therefore, warming up the battery 10 in the first mode is sometimes referred to as ripple warming.

[0045] The second warm-up mode (hereinafter simply referred to as the second mode) is a warm-up mode in which the battery 10 is warmed up by the heat generated by the electric powertrain 11. That is, in the second mode, the warm-up control unit 43 warms up the battery 10 by intentionally generating heat in the electric powertrain 11 and transporting the resulting heat to the battery 10. The warm-up control unit 43 generates the heat in the electric powertrain 11 through conduction losses in the rotating electric machine 25 and inverter 26, and switching losses in the inverter 26. Therefore, the power supplied by the battery 10 to the electric powertrain 11 is converted into thermal energy in the electric powertrain 11 and consumed.

[0046] In the second mode, the warm-up control unit 43 can generate heat in the electric powertrain 11 by, for example, heating the rotating electric machine 25 and inverter 26 included in the electric powertrain 11. For example, the warm-up control unit 43 can supply a d-axis current I to the rotating electric machine 25. d To flow, or the d-axis current I d By increasing the frequency, the rotating electric machine 25 is heated, thereby generating all or part of the necessary heat. In addition, the warm-up control unit 43 can increase the carrier frequency f2 used in the inverter 26 to, for example, a predetermined frequency set in advance for driving the rotating electric machine 25, thereby generating heat in the inverter 26, thereby generating all or part of the heat that should be generated in the electric powertrain 11.

[0047] In this embodiment, the warm-up control unit 43, in the second mode, supplies the rotating electric machine 25 with a d-axis current I d By flowing current and increasing the carrier frequency f2 of the inverter 26, the rotating electric machine 25 and the inverter 26 are heated, thereby generating heat in the electric powertrain 11. However, the warm-up control unit 43 can generate some or all of the heat that should be generated in the electric powertrain 11 by heating components other than the rotating electric machine 25 and the inverter 26.

[0048] Figure 3 shows the d-axis voltage V in the second mode. d , d-axis current I d , and battery current I bat This graph schematically shows the progression. Figure 3 is an example of the state when the rotating electric machine 25 has stopped rotating.

[0049] As shown in Figure 3(A), in the second mode, the rotating electric machine 25 has an approximately constant d-axis voltage V d Therefore, as shown in Figure 3(B), the d-axis current I flowing through the rotating electric machine 25 in the second mode is applied. d It is also generally constant. Furthermore, as shown in Figure 3(C), the battery current I bat This is also generally constant. Therefore, in the second mode, the battery 10 continues to consume the power that is converted into heat by the rotating electric machine 25, etc.

[0050] Note that the d-axis current I in the first mode d1 When it is necessary to distinguish it from the second mode, the d-axis current I flowing through the rotating electric machine 25 is used. d The d-axis current I in the second mode d2 The warm-up of battery 10 in the second mode is effectively performed by the d-axis current I d Because it converts heat into thermal energy, it is sometimes referred to as a d-axis warm-up.

[0051] The warm-up control unit 43 (see Figure 1) warms up the battery 10 faster or more energy-efficiently than if one of the warm-up modes were continuously executed, by appropriately switching between warm-up modes during the warm-up control of the battery 10. For example, when the battery temperature θ1 is at the lower limit θ min When performing warm-up control of the battery 10 from a state below the lower limit θ, the warm-up control unit 43 sets the battery temperature θ1 to the lower limit θ. min The warm-up mode is switched at least once before reaching the target temperature. In this embodiment, the warm-up control unit 43 starts warming up the battery 10 in the first mode, then switches the warm-up mode to the second mode, and sets the battery temperature θ1 to a lower limit θ min Reach the above temperature.

[0052] In addition, the warm-up control unit 43 can control the heat exchange system 12 by the temperature control unit 13 in order to warm up the battery 10. When warming up the battery 10 in at least the second mode, the warm-up control unit 43 opens the valve of the second passage 35, connects the first heat exchange unit 31 and the second heat exchange unit 32, and circulates the heat exchange medium between the first heat exchange unit 31 and the second heat exchange unit 32. As a result, the warm-up control unit 43 transports the heat generated by the electric powertrain 11 to the battery 10. Furthermore, when controlling the warm-up of the battery 10, the warm-up control unit 43 closes the valves of the first passage 34 and the third passage 36, and disconnects the connection between the first heat exchange unit 31 and the second heat exchange unit 32 and the heat exchange medium cooling unit 33. This is to prevent heat generated by the battery 10 and the electric powertrain 11 from being lost.

[0053] Figure 4 is a block diagram showing the configuration of the warm-up control unit 43. As shown in Figure 4, the warm-up control unit 43 includes (1) a first mode calculation unit 51, (2) a second mode calculation unit 52, and (3) a mode switching determination unit 53.

[0054] (1) First mode calculation unit 51 The first mode calculation unit 51 calculates the command values, etc., when warming up the battery 10 in the first mode. Specifically, the first mode calculation unit 51 calculates the first current command value I based on the state of charge (SOC) and battery temperature θ1 of the battery 10. d1 * , discharge / charge frequency command value f1 * The heat generation Q1 and the first mode efficiency E1 are calculated. The first current command value I d1 * This is the d-axis current I of the first mode. d1 This is the command value for the charging / discharging frequency command value f1. * This is the command value for the charge / discharge frequency f1 in the first mode. The heat generation Q1 is an estimated value of the amount of heat generated by the battery 10 itself when warming up the battery 10 in the first mode that contributes to the temperature rise of the battery 10 without being dissipated. The first mode efficiency E1 is the energy efficiency when warming up the battery 10 in the first mode.

[0055] Specifically, the first mode calculation unit 51 includes a first current calculation unit 61, an internal resistance calculation unit 62, and a heat generation calculation unit 63.

[0056] The first current calculation unit 61 calculates the first current command value I based on the State of Charge (SOC) and battery temperature θ1 of the battery 10. d1 * and the charge / discharge frequency command value f1 * The first current calculation unit 61 calculates the following: For example, the SOC and battery temperature θ1, and the first current command value I d1 * and the command value f1 for the charging / discharging frequency * By referring to a multidimensional map (hereinafter referred to as the first map) that associates the detected SOC and battery temperature θ1, the first current command value I is obtained. d1 * and the charge / discharge frequency command value f1 * The calculation is performed. The first map (not shown) is determined by adaptation, for example, based on experiments or simulations. The first map is stored in advance in the first current calculation unit 61 or other storage device (not shown).

[0057] Specifically, the first map contains the d-axis current I of the first mode within a range where the deposition of lithium ions, etc. (so-called electrodeposition) due to the charging and discharging of the battery 10 does not occur. d1 To maximize the first current command value I d1 * and the command value f1 for the charging / discharging frequency * A combination is set.

[0058] As a general trend, the higher the battery temperature θ1, the higher the d-axis current I in the first mode. d1 It can become larger. On the other hand, the higher the SOC, the greater the d-axis current I in the first mode. d1 It needs to be made smaller. Therefore, the first map is such that the higher the battery temperature θ1 and the lower the SOC, the first current command value I d1 * This increases the first current command value I. On the other hand, in the first map, the lower the battery temperature θ1 and the higher the SOC, the greater the first current command value I d1 * Make it smaller.

[0059] According to the first map, the first current command value I d1 * and the command value f1 for the charging / discharging frequency * Determine the d-axis current I accordingly. d1 By supplying the current to the rotating electric machine 25 at the charging / discharging frequency f1, electrodeposition is suppressed while maintaining the internal resistance R of the battery 10. bat The heat generated by Q1 is maximized.

[0060] The internal resistance calculation unit 62 calculates the internal resistance R of the battery 10 based on the state of clock (SOC) and battery temperature θ1 of the battery 10. bat The internal resistance calculation unit 62 calculates the following: For example, the SOC and battery temperature θ1, and the internal resistance R of the battery 10. bat By referring to a multidimensional map (hereinafter referred to as the second map) that associates these values, the internal resistance R corresponding to the detected SOC and battery temperature θ1 can be determined. batPerform the calculation. The second map (not shown) is determined by adaptation, for example, based on experiments or simulations. The second map is stored in advance in the internal resistance calculation unit 62 or other storage devices not shown.

[0061] As a general tendency, the higher the battery temperature θ1, the lower the internal resistance R bat becomes, and the lower the SOC, the higher the internal resistance R bat becomes. Note that the lower the battery temperature θ1, the more prominent this tendency becomes. Therefore, the second map outputs a larger internal resistance R bat when the battery temperature θ1 is low and the SOC is low.

[0062] The heat generation amount calculation unit 63 calculates the heat generation amount Q1 and the first mode efficiency E1 based on the first current command value I d1 * calculated by the first current calculation unit 61 and the internal resistance R bat calculated by the internal resistance calculation unit 62. The heat generation amount calculation unit 63 refers to a multi-dimensional map (hereinafter referred to as the third map) that associates the first current command value I d1 * and the internal resistance R bat with the heat generation amount Q1 and the first mode efficiency E1, and calculates the heat generation amount Q1 and the first mode efficiency E1 corresponding to the first current command value I d1 * and the internal resistance R bat The third map (not shown) is determined by adaptation, for example, based on experiments or simulations. The third map is stored in advance in the heat generation amount calculation unit 63 or other storage devices not shown.

[0063] As a general tendency, the larger the first current command value I d1 * is, the larger the heat generation amount Q1 becomes, and the larger the internal resistance R bat is, the larger the heat generation amount Q1 becomes. Therefore, the third map has a large first current command value I d1 * and a large internal resistance R batThe larger the value, the greater the heat output Q1. Note that the first mode efficiency E1 is determined by the first current command value I d1 * and internal resistance R bat Regardless, it remains generally constant.

[0064] (2) Second mode calculation unit 52 The second mode calculation unit 52 calculates the command values, etc., when warming up the battery 10 in second mode. Specifically, the second mode calculation unit 52 calculates the second current command value I based on the SOC and ePT temperature θ2 of the battery 10. d2 * , carrier frequency command value f2 * The transport heat quantity Q2 and the second mode efficiency E2 are calculated. The second current command value I d2 * This is the d-axis current I of the second mode. d2 This is the command value for the carrier frequency command value f2. * This is the command value for the carrier frequency f2 of the inverter 26. The transported heat quantity Q2 is the amount of heat that can be transported from the electric powertrain 11 to the battery 10 by the second mode, that is, the estimated amount of heat that the battery 10 can receive (heat received) from the heat generated in the electric powertrain 11. Therefore, the transported heat quantity Q2 is the heat generated in the electric powertrain 11 that contributes to the temperature rise of the battery 10. The second mode efficiency E2 is the energy efficiency when warming up the battery 10 in the second mode.

[0065] Specifically, the second mode calculation unit 52 comprises a second current calculation unit 64 and a transport heat quantity calculation unit 65.

[0066] The second current calculation unit 64 calculates the second current command value I based on the ePT temperature θ2. d2 * and carrier frequency command value f2 * The following is calculated. In this embodiment, the second current command value I d2 * This is maximized, for example, to the extent that the heat resistance and other durability of the rotating electric machine 25 and the inverter 26 (especially the switching elements) allow. Also, the carrier frequency command value f2* This is maximized, for example, to the extent permitted by the heat resistance and other durability of the inverter 26.

[0067] In other words, the second current calculation unit 64, in principle, sets the maximum possible second current command value I d2 * and carrier frequency command value f2 * It outputs the following. And, for example, when the ePT temperature θ2 is high and there is a risk that the rotating electric machine 25 or inverter 26 will exceed its heat resistance limit, the second current calculation unit 64 outputs the second current command value I according to the ePT temperature θ2. d2 * and carrier frequency command value f2 * This limits the current. Therefore, for example, when the electric vehicle 100 is in a low-temperature environment and the electric powertrain 11 is cold, the second current calculation unit 64 sets the maximum possible second current command value I d2 * and carrier frequency command value f2 * This outputs a signal. As a result, the heat generated in the electric powertrain 11 is maximized in the second mode.

[0068] The heat transport calculation unit 65 calculates the heat transport quantity Q2 and the second mode efficiency E2 based on the battery temperature θ1 and the ePT temperature θ2. The heat transport calculation unit 65 calculates the heat transport quantity Q2 and the second mode efficiency E2 corresponding to the battery temperature θ1 and the ePT temperature θ2 by referring to a multidimensional map (hereinafter referred to as the fourth map) that associates the battery temperature θ1 and the ePT temperature θ2 with the heat transport quantity Q2 and the second mode efficiency E2. The fourth map (not shown) is determined by adaptation, for example, based on experiments or simulations. The fourth map is stored in advance in the heat transport calculation unit 65 or other storage device (not shown).

[0069] As a general trend, the higher the ePT temperature θ2, the greater the amount of heat transported Q2. Also, the higher the battery temperature θ1, the greater the amount of heat transported Q2. Therefore, the fourth map outputs a larger amount of heat transported Q2 when both the ePT temperature θ2 and the battery temperature θ1 are high. Furthermore, the larger the difference Δθ (not shown) between the battery temperature θ1 and the ePT temperature θ2, the higher the second mode efficiency E2. Therefore, the fourth map outputs a larger second mode efficiency E2 when the difference Δθ between the battery temperature θ1 and the ePT temperature θ2 is high. In reality, there is a delay (thermal time constant τ) in heat transport from the electric powertrain 11 to the battery 10. Q This results in the following: The fourth map is designed to take into account not only the amount of heat that is dissipated during heat transport, but also these delays.

[0070] (3) Mode switching determination unit 53 The mode switching determination unit 53 determines whether and when it is necessary to switch to a warm-up mode. Then, according to the determination result, the mode switching determination unit 53 sends a signal that represents the warm-up mode setting (hereinafter referred to as warm-up mode setting S). mode ), frequency command value f * , and current command value I d * Outputs.

[0071] Warm-up mode setting S mode This indicates the selection of either the first or second mode, i.e., whether or not a warm-up mode switch is necessary and when.

[0072] The frequency command value f output by the mode switching determination unit 53 * The charge / discharge frequency command value f1 * or carrier frequency command value f2 * Specifically, when the selected warm-up mode is the first mode, the frequency command value f * is the frequency command value f * The charge / discharge frequency command value is f1 * And, if the selected warm-up mode is the second mode, the frequency command value f * This is the carrier frequency command value f2 * That is the case.

[0073] The current command value I output by the mode switching determination unit 53 d * This is the first current command value I d1 * Or the second current command value I d2 * Specifically, if the selected warm-up mode is the first mode, the current command value I d * This is the first current command value I d1 * And, if the selected warm-up mode is the second mode, the current command value I d * This is the second current command value I d2 * That is the case.

[0074] The mode switching determination unit 53 determines the warm-up mode setting S. mode , frequency command value f * , and current command value I d * This is input to the rotating electric machine control unit 42. The rotating electric machine control unit 42 then drives the rotating electric machine 25 and the inverter 26 according to the selected warm-up mode. The mode switching determination unit 53 also determines the warm-up mode setting S mode This is input to the temperature control unit 13. As a result, the temperature control unit 13 controls the pumps of the heat exchange system 12 and the valves in each of the flow paths 34, 35, and 36 according to the selected warm-up mode, thereby changing the circulation of the heat exchange medium according to the selected warm-up mode.

[0075] The mode switching determination unit 53 can determine the switching of the warm-up mode based on the heat generation amount Q1 and the heat transport amount Q2. In this case, the heat generation amount Q1 and the heat transport amount Q2 are compared, and the warm-up mode with the larger heat output is selected. That is, when the heat generation amount Q1 is greater than the heat transport amount Q2, the first mode is selected, and when the heat transport amount Q2 is greater than the heat generation amount Q1, the second mode is selected.

[0076] The mode switching determination unit 53 can determine the switching of the warm-up mode based on the first mode efficiency E1 and the second mode efficiency E2. In this case, the first mode efficiency E1 and the second mode efficiency E2 are compared, and the warm-up mode with the higher efficiency is selected. That is, when the first mode efficiency E1 is greater than the second mode efficiency E2, the first mode is selected, and when the second mode efficiency E2 is greater than the first mode efficiency E1, the second mode is selected.

[0077] The mode switching determination unit 53 can, for example, change the method for determining the switching of the warm-up mode according to the settings. In this embodiment, the settings for the mode switching determination unit 53 include, for example, a warm-up speed priority setting and an efficiency priority setting. The warm-up speed priority setting is a setting that determines the switching of the warm-up mode based on the heat generation amount Q1 and the heat transport amount Q2. The efficiency priority setting is a setting that determines the switching of the warm-up mode based on the first mode efficiency E1 and the second mode efficiency E2.

[0078] In this embodiment, the mode switching determination unit 53 selects the first mode when starting to warm up the battery 10, and then switches the selected warm-up mode to the second mode according to the determination conditions described above.

[0079] The following describes the operation of the warm-up control of the battery 10 in the electric vehicle 100 configured as described above.

[0080] Figure 5 is a schematic graph showing the changes in heat quantity and efficiency for each mode after the start of warm-up. Figure 5(A) shows the total heat quantity ΣH1 and the heat generated Q1 in the first mode. The total heat quantity ΣH1 is the total amount of heat generated in the first mode, and the heat generated Q1 is, as mentioned above, the heat from this total heat quantity ΣH1 that contributes to the temperature rise of the battery 10. Figure 5(B) shows the efficiency E1 of the first mode. Figure 5(C) shows the total heat quantity ΣH2 and the heat transported Q2 in the second mode. The total heat quantity ΣH2 is the total amount of heat generated in the second mode, and the heat transported Q2 is, as mentioned above, the heat from this total heat quantity ΣH2 that contributes to the temperature rise of the battery 10. Figure 5(D) shows the efficiency E2 of the second mode.

[0081] As shown in Figure 5(A), in the first mode, the total heat ΣH1 is relatively small, but the heat generation Q1 is relatively large relative to the total heat ΣH1 and remains roughly constant. Therefore, as shown in Figure 5(B), the first mode efficiency E1 is maintained at a relatively high level. Consequently, the first mode can warm up the battery 10 quickly and efficiently, but because the total heat ΣH1 and the corresponding heat generation Q1 are small, it takes time to warm up the battery 10.

[0082] On the other hand, as shown in Figure 5(C), in the second mode, the total heat amount ΣH2 is relatively large. Therefore, in the second mode, the total heat amount ΣH2 and the corresponding heat transport amount Q2 are large, so the battery 10 can be warmed up quickly and efficiently after a certain amount of time has passed since the start of warm-up. However, for a while after the warm-up control of the battery 10 is started, the heat transport amount Q2 is small. This is because when the electric powertrain 11 is cold, heat is taken up by the temperature rise of the electric powertrain 11 itself and cannot contribute to the temperature rise of the battery 10. Therefore, in the second mode, the battery 10 does not warm up easily and the energy efficiency is poor from the start of warm-up until the electric powertrain 11 warms up.

[0083] Therefore, in this embodiment, the warm-up mode is switched as follows, from the viewpoint of warm-up speed or energy efficiency.

[0084] Figure 6 is a graph showing the switching patterns of the warm-up mode in the warm-up speed priority setting. Figure 6(A) shows the change in heat quantity when the warm-up mode is switched with warm-up speed priority. In Figure 6(A), the heat generation amount Q1 and the transported heat amount Q2 are shown by dashed lines, and the amount of heat actually received by the battery 10 and contributed to warming up (hereinafter referred to as the heat received amount Q) is shown by a solid line. Figure 6(B) shows the change in energy efficiency when the warm-up mode is switched with warm-up speed priority. In Figure 6(B), the first mode efficiency E1 and the second mode efficiency E2 are shown by dashed lines, and the actual energy efficiency E in the warm-up speed priority setting is shown by a solid line.

[0085] As shown in Figure 6(A), in the warm-up speed priority setting, the warm-up mode is switched based on the amount of heat (heat generation Q1 and heat transport Q2). That is, after warm-up starts in the first mode, the warm-up mode switches to the second mode at time t1 when the heat transport Q2 in the second mode becomes equal to or greater than the heat generation Q1 in the first mode.

[0086] More specifically, when the warming of the battery 10 begins in the first mode, the battery 10 is warmed up by generating heat Q1 by the battery 10 itself. Also, in the first mode, the battery current I bat To generate the necessary energy, the electric powertrain 11 is energized, and heat is also generated in the electric powertrain 11. For simplicity, we assume that in the first mode, the heat generated in the electric powertrain 11 is approximately the same as the heat generated in the electric powertrain 11 in the second mode. Therefore, the amount of heat transported Q2 increases over time from the start of warming up the battery 10, similar to when warming up is started in the second mode, and at time t1, the amount of heat transported Q2 reaches the amount of heat generated Q1. Therefore, at time t1, the warming mode switches from the first mode to the second mode. As a result, after time t1, the amount of heat received by the battery 10 Q is higher than when the first mode is continued. Consequently, the battery temperature θ1 reaches the target temperature (lower limit θ) faster than when the first mode is continued. min )

[0087] On the other hand, as shown in Figure 6(B), the energy efficiency E may temporarily decrease after time t1 due to the switching of the warm-up mode. Therefore, the warm-up speed priority setting prioritizes raising the battery temperature θ1 quickly rather than maintaining a high energy efficiency E for warm-up control and suppressing power consumption of the battery 10 by using the heat generation amount Q1 and the heat transported amount Q2 (i.e., heat received amount Q) as criteria for switching the warm-up mode.

[0088] However, even with the warm-up speed priority setting, the energy efficiency E ultimately improves even further than the first-mode efficiency E1. Therefore, the overall energy efficiency (e.g., the integral of energy efficiency E) until the battery temperature θ1 reaches the target temperature is higher than when the battery temperature θ1 is brought to the target temperature by continuously using either the first or second mode. In other words, the warm-up speed priority setting described above allows the battery temperature θ1 to reach the target temperature particularly quickly, while also improving the energy efficiency of the warm-up process.

[0089] Figure 7 is a graph showing the switching patterns of the warm-up mode in the efficiency-prioritizing setting. Figure 7(A) shows the change in heat quantity when the warm-up mode is switched prioritizing energy efficiency. In Figure 7(A), as with Figure 6(A), the heat generation amount Q1 and the transported heat amount Q2 are shown as dashed lines, and the heat received by the battery 10 Q is shown as a solid line. Figure 7(B) shows the change in energy efficiency when the warm-up mode is switched prioritizing energy efficiency. In Figure 7(B), as with Figure 6(B), the first mode efficiency E1 and the second mode efficiency E2 are shown as dashed lines, and the actual energy efficiency E in the warm-up speed-prioritizing setting is shown as a solid line.

[0090] As shown in Figure 7(B), in the efficiency-priority setting, the warm-up mode is switched based on the warm-up energy efficiency (first mode efficiency E1 and second mode efficiency E2). That is, after warming up in the first mode, the warm-up mode is switched to the second mode at time t2 when the second mode efficiency E2, which is the energy efficiency of the second mode, becomes equal to or greater than the first mode efficiency E1, which is the energy efficiency of the first mode. Therefore, in the efficiency-priority setting, the warm-up energy efficiency E is maintained at or above the first mode efficiency E1, and the energy efficiency E is further improved by switching the warm-up mode.

[0091] On the other hand, in the efficiency-priority setting, the switch to the warm-up mode is delayed compared to the warm-up speed-priority setting. Specifically, as shown in Figure 7(A), in the warm-up speed-priority setting, the switch to the second mode occurs at time t1, while in the efficiency-priority setting, the warm-up mode switches at time t2, which is later.

[0092] Therefore, the efficiency-prioritizing setting prioritizes maintaining a high energy efficiency E for warm-up control over rapidly raising the battery temperature θ1, by using the first mode efficiency E1 and second mode efficiency E2 (i.e., energy efficiency E) as the criteria for switching warm-up modes.

[0093] However, even in the efficiency-prioritizing setting, the heat received Q is generally maintained at or above the heat generated Q1. As a result, the battery temperature θ1 reaches the target temperature faster than when the battery temperature θ1 is raised to the target temperature by continuously using either the first or second mode. In other words, the above efficiency-prioritizing setting not only significantly improves the energy efficiency E of the warm-up process, but also allows the battery temperature θ1 to reach the target temperature more quickly.

[0094] Figure 8 is a flowchart relating to the switching of warm-up modes. As shown in Figure 8, in this embodiment, in step S10, the warm-up of the battery 10 is started in the first mode. In step S11, the state detection unit 41 acquires the state of charge (SOC), battery temperature θ1, and ePT temperature θ2 of the battery 10. In step S12, the warm-up control unit 43 calculates the heat generation amount Q1, first mode efficiency E1, transported heat amount Q2, and second mode efficiency E2 based on the SOC, battery temperature θ1, and ePT temperature θ2 of the battery 10.

[0095] Subsequently, the warm-up control unit 43 determines whether to switch the warm-up mode according to the setting and switches the warm-up mode to the second mode. Specifically, if the setting related to the warm-up mode switching determination in step S13 is the warm-up speed priority setting, the process proceeds to step S14, where the warm-up control unit 43 compares the heat output Q1 with the heat output Q2. In step S14, if the heat output Q2 is greater than or equal to the heat output Q1, the process proceeds further to step S16, where the warm-up control unit 43 switches the warm-up mode to the second mode. Note that in step S14, as long as the heat output Q2 is less than the heat output Q1, the warm-up mode is maintained in the first mode.

[0096] On the other hand, if the setting for determining the switching of the warm-up mode in step S13 is set to the efficiency priority setting, the process proceeds to step S15, where the warm-up control unit 43 compares the first mode efficiency E1 with the second mode efficiency E2. In step S15, if the second mode efficiency E2 is greater than or equal to the first mode efficiency E1, the process proceeds further to step S16, where the warm-up control unit 43 switches the warm-up mode to the second mode. Note that in step S15, as long as the second mode efficiency E2 is less than the first mode efficiency E1, the warm-up mode is maintained in the first mode.

[0097] As described above, when the battery temperature θ1 reaches a predetermined target temperature (lower limit θ) min By switching the warm-up mode before reaching the specified time, the battery 10 can be warmed up faster and more energy-efficiently than if the battery 10 were warmed up in either the first or second warm-up mode.

[0098] In the above embodiment, the method for determining the switching of the warm-up mode is changed by setting either the warm-up speed priority setting or the efficiency speed priority setting, but it is not limited to this. The electric vehicle 100 may implement only one of the warm-up mode switching methods, either the warm-up speed priority setting or the efficiency priority setting. In this case, the warm-up control unit 43 only needs to calculate whichever of the following is used: the amount of heat generated Q1 and the amount of heat transported Q2, or the first mode efficiency E1 and the second mode efficiency E2.

[0099] In the above embodiment, the warm-up of the battery 10 is started in the first mode, but it is not limited to this. Depending on the specific balance of heat generation Q1, heat transported Q2, first mode efficiency E1, and second mode efficiency E2 in the actual electric vehicle 100, and the balance of battery temperature θ1 and ePT temperature θ2 at the time the warm-up is started, the warm-up of the battery 10 may be started in the second mode. In this case as well, it is preferable to switch the warm-up mode based on the heat generation Q1 and heat transported Q2 (i.e., heat received Q), or based on the first mode efficiency E1 and second mode efficiency E2 (i.e., energy efficiency E), similar to the above embodiment. This improves the warm-up speed and the energy efficiency of the warm-up.

[0100] However, in most cases, it is preferable to start warming up the battery 10 in the first mode, as in the embodiment described above, and then switch the warm-up mode to the second mode. The reason for this is that a typical scenario in which the battery 10 should be warmed up is when attempting to start the electric vehicle 100 from a state in which both the battery 10 and the electric powertrain 11 are cold, and the balance between the amount of heat generated Q1, the amount of heat transported Q2, the first mode efficiency E1, and the second mode efficiency E2 is often as shown in Figures 5 to 7.

[0101] In the above embodiment, for simplicity, the warm-up mode is switched once, but in practical situations, the warm-up mode may be switched two or more times. In this case as well, the criteria for switching the warm-up mode can be the heat generation amount Q1 and the heat transported amount Q2 (i.e., heat received amount Q), or the first mode efficiency E1 and the second mode efficiency E2 (i.e., energy efficiency E), as in the above embodiment.

[0102] In addition, in the warm-up control of the battery 10 in the above embodiment, it is preferable that the flow path of the heat exchange medium in the heat exchange system 12 is controlled as follows.

[0103] Figure 9 is a flowchart relating to the flow path control of the heat exchange medium. As shown in Figure 9, when warming up the battery 10, in step S20, the connection between the first heat exchange section 31 and the second heat exchange section 32 and the heat exchange medium cooling section 33 is released. Also, in step S21, the connection between the first heat exchange section 31 and the second heat exchange section 32 is also released. As a result, both the first heat exchange section 31 and the second heat exchange section 32 become isolated. Therefore, the heat generated in the battery 10 (total heat amount ΣH1) is less likely to be absorbed by the first heat exchange section 31. As a result, the amount of heat generated Q1 increases, and the first mode efficiency E1 increases. In addition, the heat generated in the electric powertrain 11 (total heat amount ΣH2) is less likely to be absorbed by the second heat exchange section 32. As a result, the electric powertrain 11 warms up faster.

[0104] Subsequently, in step S22, the warm-up of the battery 10 is started in the first mode. In step S23, as in the embodiment described above, a determination is made to switch the warm-up mode based on the heat generation amount Q1 and the heat transport amount Q2, or based on the first mode efficiency E1 and the second mode efficiency E2. If the conditions for switching to the second mode are met in step S23, the process proceeds to step S24, where the first heat exchange unit 31 and the second heat exchange unit 32 are connected. This makes it easier for the heat generated in the electric powertrain 11 to be transported to the battery 10 via the first heat exchange unit 31 and the second heat exchange unit 32. In other words, the heat transport amount Q2 and the second mode efficiency E2 become larger than when the first heat exchange unit 31 and the second heat exchange unit 32 are not connected.

[0105] In this example, the determination of whether to switch to warm-up mode uses the amount of heat generated Q1 and the first mode efficiency E1 when the first heat exchange unit 31 and the second heat exchange unit 32 are not connected, and the amount of heat transported Q2 and the second mode efficiency E2 when the first heat exchange unit 31 and the second heat exchange unit 32 are connected.

[0106] As described above, when warming up the battery 10 in at least the second mode, connecting the first heat exchange unit 31 and the second heat exchange unit 32, and transporting the heat generated in the electric powertrain 11 to the battery 10 using a heat exchange medium that flows commonly between the first heat exchange unit 31 and the second heat exchange unit 32, increases the transported heat amount Q2 and the second mode efficiency E2. For this reason, in the second mode, the battery 10 is warmed up particularly quickly and efficiently.

[0107] Furthermore, as described above, in the first mode, the connection between the first heat exchange unit 31 and the second heat exchange unit 32 is disconnected, and when switching from the warm-up mode to the second mode, the first heat exchange unit 31 and the second heat exchange unit 32 are connected, allowing the battery 10 to warm up quickly and energy-efficiently. This is because in the first mode, the heat generated in the battery 10 is less likely to dissipate, while in the second mode, the amount of heat transported Q2 increases.

[0108] Figure 10 is a flowchart relating to flow path control in a modified example. As shown in Figure 10, in step S30, the connection between the first heat exchange unit 31 and the second heat exchange unit 32 and the heat exchange medium cooling unit 33 is released. On the other hand, in step S31, the first heat exchange unit 31 and the second heat exchange unit 32 are connected. In other words, in this example, regardless of whether the warm-up mode is the first mode or the second mode, heat is transported between the battery 10 and the electric powertrain 11 via the first heat exchange unit 31 and the second heat exchange unit 32 from the start of warm-up.

[0109] Subsequently, in step S32, the warm-up of the battery 10 is started in the first mode. In step S33, a determination is made to switch the warm-up mode based on the heat generation amount Q1 and the heat transport amount Q2, or based on the first mode efficiency E1 and the second mode efficiency E2. If the conditions for switching to the second mode are met in step S33, the process proceeds to step S34, and the warm-up mode is switched to the second mode.

[0110] As described above, when the first heat exchange unit 31 and the second heat exchange unit 32 are connected when the battery 10 is warmed up, heat is transported between the battery 10 and the electric powertrain 11 via the first heat exchange unit 31 and the second heat exchange unit 32 from the start of warming up. As a result, some of the heat that would otherwise be dissipated from the battery 10 in the first mode warms the electric powertrain 11, thus accelerating the timing of switching to the second mode. Consequently, the battery temperature θ1 reaches the target temperature particularly quickly, and the energy efficiency until the battery temperature θ1 reaches the target temperature is particularly improved.

[0111] Furthermore, in the first mode, due to conduction losses, some of the heat generated in the electric powertrain 11 is transported to the battery 10, contributing to the temperature rise of the battery 10. Therefore, in the first mode, the battery 10 is warmed up particularly quickly and efficiently. In other words, the warm-up speed and energy efficiency in the first mode are improved.

[0112] Figure 11 is a flowchart relating to flow path control of a modified example. As shown in Figure 11, in step S40, the connection between the first heat exchange unit 31 and the second heat exchange unit 32 and the heat exchange medium cooling unit 33 is released. Also, in step S41, the connection between the first heat exchange unit 31 and the second heat exchange unit 32 is released. Then, in step S42, the warming of the battery 10 is started in first mode.

[0113] Subsequently, in step S43, the first heat exchange unit 31 and the second heat exchange unit 32 are connected. That is, in this example, after the warm-up of the battery 10 is started in the first mode, and before the warm-up mode is switched to the second mode, the first heat exchange unit 31 and the second heat exchange unit 32 are connected, and heat transport between the battery 10 and the electric powertrain 11 is started during the first mode.

[0114] Then, in step S44, a decision is made to switch the warm-up mode based on the heat output Q1 and the heat transported Q2, or based on the first mode efficiency E1 and the second mode efficiency E2. If the conditions for switching to the second mode are met in step S44, the process proceeds to step S45, and the warm-up mode is switched to the second mode.

[0115] As described above, by connecting the first heat exchange unit 31 and the second heat exchange unit 32 after starting the warm-up of the battery 10 in the first mode, and before switching the warm-up mode from the first mode to the second mode, the advantages of the flow path control in Figure 9 and the modified flow path control in Figure 10 can be obtained. In other words, the battery 10 is warmed up quickly and energy-efficiently.

[0116] As described above, the battery warming method according to this embodiment ensures that the temperature (θ1) of the battery 10 that supplies power to the electric powertrain 11 in the electric vehicle 100 reaches a predetermined temperature (θ min When the temperature (θ1) of the battery 10 is lower than a predetermined temperature (θ min This is a battery warming method for warming up the battery 10 when it is expected that the temperature (θ1) will be lower than a predetermined temperature (θ). This battery warming method includes, as warming modes for warming up the battery 10, a first mode in which the battery 10 is warmed up by the heat (Q1) generated by the battery 10 itself, and a second mode in which the battery is warmed up by the heat (Q2) generated by the electric powertrain 11. min Before reaching that point, the system switches between the first mode and the second mode.

[0117] Thus, when the battery temperature θ1 reaches a predetermined target temperature (lower limit θ) min By switching the warm-up mode before reaching the specified time, the battery 10 can be warmed up faster and more energy-efficiently than if the battery 10 were warmed up in either the first or second warm-up mode.

[0118] In the battery warming method according to the above embodiment, the warming of the battery 10 is started in the first mode, and the temperature of the battery 10 (θ1) reaches a predetermined temperature (θ min Before reaching ), the warm-up mode is switched from mode 1 to mode 2.

[0119] A typical scenario in which the battery 10 should be warmed up is when attempting to start the electric vehicle 100 from a state where both the battery 10 and the electric powertrain 11 are cold. Furthermore, the balance between the amount of heat generated Q1, the amount of heat transported Q2, the first mode efficiency E1, and the second mode efficiency E2 is often as shown in Figures 5 to 7. Therefore, as described above, by starting the warm-up of the battery 10 in the first mode and then switching the warm-up mode to the second mode, the battery 10 can be warmed up quickly and energy-efficiently.

[0120] In the battery warm-up method according to the above embodiment, the amount of heat generated by the battery 10, Q1, is calculated in the first mode, and the amount of heat transported, Q2, which is the amount of heat transported from the electric powertrain 11 to the battery 10, is calculated in the second mode. When the amount of heat transported, Q2, becomes equal to or greater than the amount of heat generated, the warm-up mode is switched from the first mode to the second mode.

[0121] In this way, by using the heat generation amount Q1 and the heat transported amount Q2 (i.e., the heat received amount Q) as the criteria for switching to the warm-up mode, the battery temperature θ1 can reach the target temperature particularly quickly, and the energy efficiency of the warm-up process is also improved.

[0122] In the battery warm-up method according to the above embodiment, the first mode efficiency E1, which is the energy efficiency when the battery 10 itself is heated in the first mode, is calculated, and the second mode efficiency E2, which is the energy efficiency when the electric powertrain 11 is heated and heat is transported from the electric powertrain 11 to the battery 10, is calculated in the second mode. When the second mode efficiency E2 is equal to or greater than the first mode efficiency E1, the warm-up mode is switched from the first mode to the second mode.

[0123] In this way, by using the first mode efficiency E1 and the second mode efficiency E2 (i.e., energy efficiency E) as the criteria for switching to the warm-up mode, the energy efficiency E of the warm-up can be particularly improved, and the battery temperature θ1 can reach the target temperature more quickly.

[0124] In the battery warming method according to the above embodiment, when warming up the battery 10 in at least the second mode, a first heat exchange unit 31 that exchanges heat with the battery 10 and a second heat exchange unit 32 that exchanges heat with the electric powertrain 11 are connected, and heat generated in the electric powertrain 11 is transported to the battery 10 by a medium (heat exchange medium) that flows in common between the first heat exchange unit 31 and the second heat exchange unit 32.

[0125] Thus, when the battery 10 is warmed up in at least the second mode, the heat generated in the electric powertrain 11 is transported to the battery 10, allowing the battery 10 to warm up particularly quickly and efficiently in the second mode. Furthermore, throughout the entire warm-up process, including switching between the first and second modes, the battery 10 is warmed up quickly and energy-efficiently.

[0126] In the battery warming method according to the above embodiment, the first heat exchange unit 31 and the second heat exchange unit 32 can be connected when warming up the battery 10 is started.

[0127] In this case, the battery temperature θ1 reaches the target temperature particularly quickly, and the energy efficiency until the battery temperature θ1 reaches the target temperature is particularly improved. In addition, the warm-up speed and energy efficiency of the first mode are improved.

[0128] In the battery warming method according to the above embodiment, after starting the warming of the battery 10 in the first mode, the first heat exchange unit 31 and the second heat exchange unit 32 can be connected before switching the warming mode from the first mode to the second mode.

[0129] In this case, the warm-up speed and energy efficiency are improved in both the first and second modes. Therefore, throughout the entire warm-up process, including switching between the first and second modes, the battery 10 is warmed up quickly and energy-efficiently.

[0130] In the battery warming method according to the above embodiment, the first mode involves storing energy in the elements (windings 27) included in the electric powertrain 11 by discharging the battery 10, charging the battery 10 with the energy stored in those elements (windings 27), and repeating the discharging and charging process, thereby reducing the internal resistance R of the battery 10. bat This causes the battery 10 itself to generate heat.

[0131] In this way, by utilizing the elements included in the electric powertrain 11, the battery 10 can be warmed up quickly and efficiently without the need to provide any new elements for the first mode.

[0132] In the battery warming method according to the above embodiment, the second mode involves supplying a d-axis current I to the rotating electric machine 25 included in the electric powertrain 11. d2 By flowing this fluid, heat is generated in the electric powertrain 11.

[0133] In this way, by utilizing the rotating electric motor 25, the battery 10 can be warmed up quickly and efficiently without the need to install any new elements for the second mode.

[0134] In the battery warming method according to the above embodiment, the second mode generates heat in the inverter 26 by increasing the carrier frequency f2 used in the inverter 26 that drives the rotating electric machine 25 to a predetermined frequency set in advance for driving the rotating electric machine 25.

[0135] In this way, by changing the carrier frequency f2 of the inverter 26, the battery 10 is warmed up quickly and efficiently in the second mode.

[0136] The battery warming device according to the above embodiment ensures that the temperature (θ1) of the battery 10 that supplies power to the electric powertrain 11 in the electric vehicle 100 reaches a predetermined temperature (θ min When the temperature (θ1) of the battery 10 is lower than a predetermined temperature (θ min This is a battery warming device (controller 14) that warms up the battery 10 when it is expected that the temperature will fall below a predetermined temperature (θ). This control device (controller 14) has two warming modes for warming up the battery 10: a first mode in which the battery 10 is warmed up by the heat generated by the battery 10 itself, and a second mode in which the battery 10 is warmed up by the heat generated by the electric powertrain 11. min Before reaching ), it switches between the first mode and the second mode.

[0137] Thus, when the battery temperature θ1 reaches a predetermined target temperature (lower limit θ) min By switching the warm-up mode before reaching the specified time, the battery 10 can be warmed up faster and more energy-efficiently than if the battery 10 were warmed up in either the first or second warm-up mode.

[0138] Although embodiments of the present invention have been described above, the configurations described in the above embodiments and each of the modifications represent only a part of the application examples of the present invention and are not intended to limit the technical scope of the present invention.

Claims

1. A battery warming method for an electric vehicle, in which the temperature of the battery that supplies power to the electric powertrain is lower than a predetermined temperature, or when the temperature of the battery is expected to fall below the predetermined temperature, The warm-up mode for warming up the battery includes a first mode in which the battery is warmed up by the heat generated by the battery itself, and a second mode in which the battery is warmed up by the heat generated by the electric powertrain. After warming up begins, the system switches between the first mode and the second mode until the battery temperature reaches the predetermined temperature. Battery warm-up method.

2. A battery warming method according to claim 1, In the first mode, start warming up the battery. The warm-up mode is switched from the first mode to the second mode before the battery temperature reaches the predetermined temperature. Battery warm-up method.

3. A battery warming method according to claim 2, The amount of heat generated by the battery in the first mode is calculated, In the second mode described above, the amount of heat transported, which is the amount of heat transported from the electric powertrain to the battery, is calculated. When the amount of heat transported becomes equal to or greater than the amount of heat generated, the warm-up mode is switched from the first mode to the second mode. Battery warm-up method.

4. A battery warming method according to claim 2, The first mode efficiency, which is the energy efficiency when the battery itself generates heat in the first mode, is calculated. In the second mode, the electric powertrain is heated, and the second mode efficiency, which is the energy efficiency when heat is transported from the electric powertrain to the battery, is calculated. When the efficiency of the second mode becomes equal to or greater than the efficiency of the first mode, the warm-up mode is switched from the first mode to the second mode. Battery warm-up method.

5. A battery warming method according to any one of claims 1 to 4, At least when warming up the battery in the second mode, a first heat exchange unit that exchanges heat with the battery and a second heat exchange unit that exchanges heat with the electric powertrain are connected. The heat generated in the electric powertrain is transported to the battery by a medium that flows in common between the first heat exchange section and the second heat exchange section. Battery warm-up method.

6. A battery warming method according to claim 5, When starting the warm-up of the battery, the first heat exchange unit and the second heat exchange unit are connected. Battery warm-up method.

7. A battery warming method according to claim 5, After starting the warm-up of the battery in the first mode, and before switching the warm-up mode from the first mode to the second mode, the first heat exchange unit and the second heat exchange unit are connected. Battery warm-up method.

8. A battery warming method according to claim 1, The first mode involves storing energy in elements of the electric powertrain by discharging the battery, charging the battery with the energy stored in the elements, and repeating the discharging and charging process, thereby generating heat in the battery itself due to its internal resistance. Battery warm-up method.

9. A battery warming method according to claim 1, The second mode generates heat in the electric powertrain by passing a d-axis current through the rotating electric machine included in the electric powertrain. Battery warm-up method.

10. A battery warming method according to claim 9, The second mode generates heat in the inverter by increasing the carrier frequency used in the inverter that drives the rotating electric machine to a predetermined frequency set in advance for driving the rotating electric machine. Battery warm-up method.

11. A battery warming device for an electric vehicle, which warms up the battery when the temperature of the battery supplying power to the electric powertrain is lower than a predetermined temperature, or when the temperature of the battery is expected to fall below the predetermined temperature, The aforementioned battery warming device is The warm-up mode for warming up the battery includes a first mode in which the battery is warmed up by the heat generated by the battery itself, and a second mode in which the battery is warmed up by the heat generated by the electric powertrain. After warming up begins, the system switches between the first mode and the second mode until the battery temperature reaches the predetermined temperature. Battery warm-up device.

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