Thermal energy control system, thermal energy control method, and thermal energy control device

Abstract

According to a thermal energy control system, a thermal energy control method, and a thermal energy control device of the present invention, in one embodiment, a vehicle is provided with a plurality of heat sources and at least one heating request unit for generating a heating request in accordance with conditions, wherein a priority is set for each of the plurality of heat sources in response to a heating request generated at the heating request unit, and a heating heat source, among the plurality of heat sources, to be used to heat the heating request unit is selected on the basis of priority. Due to this configuration, it is possible to accelerate the rise in temperature at the heating request unit as much as possible while also keeping power consumption low.

Description

Thermal energy control system, thermal energy control method, and thermal energy control device

[0001] The present invention relates to a thermal energy control system, a thermal energy control method, and a thermal energy control device.

[0002] The thermal energy control system disclosed in Patent Document 1 includes a plurality of heat sources and a heat distributor that allocates the requested heat amount calculated from the heat demand generated throughout the vehicle to the plurality of heat sources based on the heat supply capacity, which is the maximum amount of heat that each of the plurality of heat sources can supply. Priorities are set for the heat demand generated throughout the vehicle, and if the total amount of heat supply capacity of the heat sources is small compared to the requested heat amount, the heat distributor discards the heat demand that is set with a relatively low priority.

[0003] Patent No. 7114920

[0004] However, in a thermal energy control system that prioritizes heat demands, among multiple heat demand units that generate heat demands depending on conditions, the temperature rise of a unit with a lower priority may be slower, which may result in the vehicle being unable to fully demonstrate its performance. Also, if the shortage of heat is uniformly compensated for by a heat source that intentionally generates heat, this may result in an increase in power consumption.

[0005] Therefore, an object of the present invention is to provide a thermal energy control system, a thermal energy control method, and a thermal energy control device that can reduce power consumption while accelerating the temperature rise of a unit requiring heating as quickly as possible.

[0006] In one aspect, the thermal energy control system, thermal energy control method, and thermal energy control device of the present invention set priorities for each of a plurality of heat sources in response to a heating request generated by a heating request unit, and select a heating heat source from the plurality of heat sources to be used to heat the heating request unit based on the priority.

[0007] According to the present invention, it is possible to reduce power consumption while accelerating the temperature rise of the heating-requesting unit as much as possible.

[0008] 1 is a block diagram showing one embodiment of the configuration of a thermal energy control system; FIG. 2 is a diagram showing one embodiment of a piping structure for heating; FIG. 3 is a diagram showing a piping structure for supplying heat to a gear portion of an electric axle via a heat medium; FIG. 4 is a diagram showing a piping structure for exchanging heat between gear oil of an electric axle and a heat medium; FIG. 5 is a flowchart showing a process for calculating thermal efficiency; FIG. 6 is a flowchart showing a process for selecting a heat source; FIG. 7 is a flowchart showing a process for determining the priority of heating targets; FIG. 8 is a flowchart showing a process for selecting a heat source according to a charging method.

[0009] Hereinafter, embodiments of a thermal energy control system, a thermal energy control method, and a thermal energy control device according to the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing one aspect of the configuration of a thermal energy control system. The thermal energy control system 100 shown in Fig. 1 is a system mounted on an electric vehicle 200 (in other words, an electric automobile).

[0010] The electric vehicle 200 has a lithium ion battery 201 (driving battery system) which is a driving battery, and an electric axle 202 (axle system). The electric axle 202 is a drive unit that packages a motor, an inverter, and a transaxle, which constitute the power train of the electric vehicle 200, and the driving motor that constitutes the electric axle 202 operates using the lithium ion battery 201 as a power source.

[0011] Here, in a low temperature state where the temperature of the lithium ion battery 201 is below a set temperature, by heating the lithium ion battery 201 and increasing the temperature, the capacity of the lithium ion battery 201 is restored and the driving distance of the electric vehicle 200 is improved. Also, in a low temperature state where the temperature of the gear oil of the electric axle 202 is below a set temperature, by heating the gear oil of the electric axle 202 and increasing the temperature, the power transmission efficiency is increased and the electricity consumption of the electric vehicle 200 is improved.

[0012] Therefore, the thermal energy control system 100 has a function of actively heating the lithium ion battery 201 and the electric axle 202 (gear oil) using a heat source provided in the electric vehicle 200 in a heating request state where the temperatures of the lithium ion battery 201 and the electric axle 202 (gear oil) are below a set temperature. In other words, the lithium ion battery 201 and the electric axle 202 correspond to heating request units that issue a heating request depending on the conditions, and the heating request is determined, for example, as a state where the temperature of the heating request unit is below a set temperature. In other words, the lithium ion battery 201 and the electric axle 202 are heating request units that issue a heating request depending on the temperature conditions.

[0013] Furthermore, thermal energy control system 100 has the function of setting priorities for each of multiple heat sources provided in electric vehicle 200 in response to heating requests from lithium ion battery 201 and electric axle 202, selecting a heating heat source to be used for heating lithium ion battery 201 and electric axle 202 from among the multiple heat sources based on the priorities, and supplying heat generated by the heat source selected as the heating heat source to the heat requesting unit. Lithium ion battery 201, electric axle 202, and the multiple heat sources are connected by pipes through which a heat medium such as water or oil flows, and heat is supplied from the heating heat source to lithium ion battery 201 and electric axle 202 via the heat medium flowing through the pipes.

[0014] Here, the pipes through which the heat medium flows are configured to be able to supply the heat medium individually to the lithium ion battery 201 and the electric axle 202, and the circulation path of the heat medium is switched depending on whether or not there is a heating request for the lithium ion battery 201 and the electric axle 202, and further depending on the heat source selected as the heating heat source. Selection of the heat source used to heat the lithium ion battery 201 and the electric axle 202 (including an instruction to generate heat at the heat source) and switching of the circulation path of the heat medium are executed by the thermal energy control device 300.

[0015] Here, the thermal energy control device 300 first selects the heat source with the highest priority as the heating heat source for heating the lithium ion battery 201 and the electric axle 202. Then, if the amount of heat supplied is insufficient for the required amount of heat (in other words, if the temperature does not rise to the set temperature), the thermal energy control device 300 adds and uses the heat source with the next highest priority, and performs a process of gradually increasing the heat source used for heating in order of priority until the required amount of heat is secured.

[0016] The multiple heat sources provided in the electric vehicle 200 include an OBC (on-board charger) 211, a traction motor 212, the lithium ion battery 201, an ECH (electric coolant heater) 213, an inverter 214, and a heat pump 215. The OBC 211 is a device used to charge the lithium ion battery 201, converts electric power from an external power source into a voltage required for the lithium ion battery 201, and generates heat (waste heat) during this voltage conversion.

[0017] The traction motor 212 constitutes the electric axle 202, and generates heat (waste heat) as a driving torque (load) is generated when the electric vehicle 200 is traveling. The lithium ion battery 201 is a self-heating battery that has the function of increasing the temperature inside the battery by self-heating. The ECH 213 is a device that heats the interior of the electric vehicle 200 by circulating water heated by an electric heater, and generates heat to heat the interior of the vehicle.

[0018] The inverter 214 is a component of the electric axle 202, is used to control the rotation speed of the traction motor 212, and generates heat (waste heat) due to internal resistance when a current flows through the inverter 214 to drive the traction motor 212. The heat pump 215 is a component of the air conditioning system that heats the interior of the electric vehicle 200 by utilizing heat from outside air and repeatedly compressing, liquefying, and evaporating a heat medium, and generates heat for heating the interior of the vehicle.

[0019] The thermal energy control device 300 is an electronic control device equipped with a microcomputer 310. The microcomputer 310 includes, as software, functional units: a required heat quantity determination unit 311, a heat source determination unit 312, and a heat quantity distribution unit 313. The required heat quantity determination unit 311 is a functional unit that calculates the required heat quantities for heating the lithium ion battery 201 and the electric axle 202.

[0020] The heat source determination unit 312 is a functional unit that selects a heating heat source to be used for heating the lithium ion battery 201 and the electric axle 202 from among a plurality of heat sources including the OBC 211. The heat quantity distribution unit 313 is a functional unit that controls the distribution of heat generated by the heat source selected by the heat source determination unit 312 to the lithium ion battery 201 and the electric axle 202.

[0021] The requested heat quantity determination unit 311 has a first requested heat quantity determination unit 311A ​​that calculates a target heat quantity (or target temperature) that serves as an index for the heating request for the lithium ion battery 201, and a second requested heat quantity determination unit 311B that calculates a target heat quantity (or target temperature) that serves as an index for the heating request for the electric axle 202. The heat source determination unit 312 acquires information on the target heat quantity (or target temperature) determined by the first requested heat quantity determination unit 311A ​​and information on the target heat quantity (or target temperature) determined by the second requested heat quantity determination unit 311B, and further acquires various signals that indicate the status of the electric vehicle 200.

[0022] The various signals indicating the status of the electric vehicle 200 include a detection signal of the vehicle speed V, which is the traveling speed of the electric vehicle 200, signals of temperature detection values ​​of the lithium ion battery 201 and the electric axle 202 (gear oil) by a temperature sensor, signals of the state of charge SOC of the lithium ion battery 201 and the auxiliary battery, and charging information of the lithium ion battery 201. The temperature signals of the lithium ion battery 201 and the electric axle 202 (gear oil) can be temperature signals correlated with the temperature of the lithium ion battery 201 or the temperature of the electric axle 202 (gear oil), and can also be estimated values ​​instead of detected values.

[0023] The heat source determination unit 312 has a first heat source determination unit 312A and a second heat source determination unit 312B. The first heat source determination unit 312A determines the heat source to be used for heating the lithium ion battery 201 based on the acquired various information. Specifically, the first heat source determination unit 312A sets a priority for each of the six heat sources, namely the OBC 211, the traction motor 212, the lithium ion battery 201, the ECH 213, the inverter 214, and the heat pump 215, and selects the heat source to be used for heating the lithium ion battery 201 from among the six heat sources based on the priority. In other words, the first heat source determination unit 312A selects the heat source to be used for heating the lithium ion battery 201 in accordance with the priority order set for the six heat sources.

[0024] Furthermore, the second heat source determination unit 312B determines the heat source to be used for heating the electric axle 202 (gear oil) based on the various acquired information. Specifically, the second heat source determination unit 312B sets a priority for each of the five heat sources, namely the OBC 211, the traction motor 212, the ECH 213, the inverter 214, and the heat pump 215, and selects the heat source to be used for heating the electric axle 202 (gear oil) from among the five heat sources based on the priority. In other words, the second heat source determination unit 312B selects the heat source to be used for heating the electric axle 202 (gear oil) in accordance with the priority order set for the five heat sources.

[0025] In the selection of a heating heat source based on priority in the first heat source determination unit 312A and the second heat source determination unit 312B, the heat source with the highest priority is first used as the heating heat source, and if the amount of heat supplied is insufficient (if the temperature does not rise to the set temperature), the heat source with the next highest priority is added, and this process is repeated sequentially until the requested amount of heat is secured. In other words, the first heat source determination unit 312A and the second heat source determination unit 312B gradually increase the heat source used for heating in accordance with the priority of the heat source, and secure the amount of heat requested by the heating requesting unit.

[0026] The heat source determination unit 312 can remove a heat source that has detected a failure from among the multiple heat sources used to heat the heating requesting unit, and select a heat source with the next highest priority after the removed heat source as the heating heat source. According to this configuration, by selecting a heat source that cannot actually supply heat as the heating heat source, it is possible to prevent delays in temperature rise of the heating requesting unit and power consumption due to the operation of a heat source that cannot supply heat.

[0027] Here, the priority of each heat source can be changed depending on the status of electric vehicle 200, such as whether it is running or not, whether it is being charged or not, whether the power is on or off, etc. For example, the status of electric vehicle 200 can be classified into a plurality of categories based on combinations of whether the power of electric vehicle 200 is on or off, whether lithium ion battery 201 is being charged or not, whether charging is performed using a DC charger or an AC charger, etc., and the priority of the heat source can be changed for each category (in other words, for each status of electric vehicle 200). This makes it possible to select the optimal heat source in terms of temperature rise performance and power saving for each status of electric vehicle 200.

[0028] Furthermore, as will be explained in detail later, when setting the priority of heat sources, heat sources that generate heat as a result of their operation (in other words, heat sources whose primary purpose is not to generate heat but which generate heat secondarily) can be prioritized, and heat sources that intentionally generate heat (in other words, heat sources that are operated with the intention of generating heat) can be prioritized. In other words, waste heat is used preferentially to meet the heating request of a heat-requesting unit, and when the amount of heat from waste heat alone is insufficient, heat sources that intentionally generate heat are used as additional heating sources. This makes it possible to ensure the amount of heat required by the heat-requesting unit while avoiding the use of heat sources that intentionally generate heat as much as possible, thereby reducing power consumption and accelerating the temperature rise of the heat-requesting unit as much as possible.

[0029] Of the above-mentioned heat sources, the OBC 211, the traction motor 212, the lithium-ion battery 201, and the inverter 214 are heat sources that generate heat (waste heat) during operation. On the other hand, of the above-mentioned heat sources, the ECH 213 and the heat pump 215 are heat sources that intentionally generate heat, in other words, heat sources that generate heat in response to a control command (operation command) that aims to generate heat.

[0030] As will be described later, the traction motor 212 and the inverter 214 can also be used as heat sources that intentionally generate heat. Furthermore, when a heat source generates more heat than is required for propulsion of the electric vehicle 200, the amount of heat generated in excess of that required for propulsion can be considered to be intentional heat generation. The priority of the heat source can be changed depending on the magnitude of loss in the heat transfer between the heating requesting unit and the heat source (in other words, thermal efficiency). In other words, a heat source with small heat loss and high thermal efficiency can be prioritized, and a heat source with relatively large heat loss and relatively low thermal efficiency can be prioritized.

[0031] By selecting a heat source according to the priority, it is possible to reduce power consumption while quickly raising the temperature of the lithium-ion battery 201 and the electric axle 202 (gear oil) to the required temperature. This makes it possible to stably and energy-savingly obtain the effect of improving the driving distance by raising the temperature of the lithium-ion battery 201 and the effect of improving the power consumption by raising the temperature of the electric axle 202 (gear oil).

[0032] 2 shows one embodiment of a piping structure for circulating LLC (long life coolant) as a heat medium through the lithium ion battery 201 and the electric axle 202 (travel motor 212). The heat medium piping 401 in Fig. 2 includes a first piping 401A to which a radiator 411 and a condenser 412 are connected, a second piping 401B to which the lithium ion battery 201, a first pump 402, and a chiller 403 are connected, and a third piping 401C to which a power control unit 404 (hereinafter referred to as PCU 404) including the travel motor 212, the OBC 211, and the inverter 214, and a second pump 405 are connected.

[0033] The circulation of the heat medium to the first pipe 401A, the second pipe 401B, and the third pipe 401C is switched by a switching valve 406 that is electronically controlled by the thermal energy control device 300 (microcomputer 310). The chiller 403 includes a compressor 403A that compresses the refrigerant gas. The gear oil of the transaxle of the electric axle 202 is also used to cool the traction motor 212.

[0034] For example, when a request to heat the electric axle 202 (transaxle gear oil) occurs during charging of the lithium ion battery 201, for which voltage conversion is performed by the OBC 211, the flow direction of the heat medium is switched by the switching valve 406 so that the heat medium circulates in the order of the traction motor 212, the OBC 211, and the PCU 404 in the third piping 401C, as shown by the thick arrow in Figure 2.

[0035] As a result, heat (waste heat) generated by the OBC 211 is supplied to the electric axle 202, and further, by controlling the supply of current to the traction motor 212 and the PCU 404 so that they generate heat themselves, the traction motor 212 and the PCU 404 are added as heating sources, and it is possible to ensure the amount of heat required to heat the electric axle 202. Note that if the amount of heat required to heat the electric axle 202 can be met by the heat generated by the OBC 211, the supply of current is not controlled to cause the traction motor 212 and the PCU 404 to generate heat themselves, and the electric axle 202 is heated only by the heat generated by the OBC 211.

[0036] The energization control that causes the traction motor 212 and the PCU 404 to generate heat by themselves is a control that sets the q-axis current of the traction motor 212 to zero and passes a d-axis current, thereby causing heat due to losses caused by energization to be generated in the inverter 214 and the traction motor 212. In other words, the inverter 214 and the traction motor 212 serve as heat sources that generate heat (waste heat) as they operate when the electric vehicle 200 is running using the traction motor 212, and can be used as heat sources that intentionally generate heat when the electric vehicle 200 is stopped. In the state shown in FIG. 2 , the electric axle 202 (gear oil) is heated by a combination of the OBC 211, which is a heat source that generates heat as it operates, and the traction motor 212 and the inverter 214, which are heat sources that intentionally generate heat.

[0037] In a system using LLC as the heat medium circulated through piping 401, either a method of transferring heat between the gear portion (transaxle) of electric axle 202 and the LLC, thereby indirectly raising the temperature of the gear oil by heating the gear portion, or a method of transferring heat using a heat exchanger between the LLC and the gear oil, thereby directly heating the gear oil, can be employed. Figure 3 shows a piping structure in which heat is supplied to the gear portion of electric axle 202 via LLC, and Figure 4 shows a piping structure in which heat is exchanged between the LLC and gear oil in heat exchanger 421.

[0038] The following describes in detail the process performed by the thermal energy control device 300 (microcomputer 310) to set the priority of the heat source in response to a request to heat the lithium ion battery 201 and the electric axle 202. First, the thermal energy control device 300 determines whether to heat the lithium ion battery 201 and the electric axle 202 based on, for example, a comparison between the temperatures of the lithium ion battery 201 and the electric axle 202 and a temperature threshold.

[0039] For example, the thermal energy control device 300 can determine a state in which the temperature of the lithium ion battery 201 is 20° C. or lower as a state in which heating of the lithium ion battery 201 is required, and can determine a state in which the temperature of the electric axle 202 (gear oil) is 60° C. or lower as a state in which heating of the electric axle 202 (gear oil) is required. Furthermore, in response to a heating request for the lithium ion battery 201 or the electric axle 202 (gear oil), the thermal energy control device 300 sets the priority of the heat source to be used for heating (in other words, the order of priority of the heat source) according to the status of the electric vehicle 200.

[0040] The status of the electric vehicle 200 related to the setting of the priority is first distinguished by whether the power supply of the electric vehicle 200 is on or off, and further distinguished by whether the lithium ion battery 201 is being charged or not even when the power supply is off. Furthermore, the charging status is distinguished by charging using a DC charger (rapid charging, high-output charging) and charging using an AC charger (normal charging, low-output charging).

[0041] Furthermore, as described above, the thermal energy control device 300 can prioritize heat sources that generate heat during operation and prioritize heat sources that intentionally generate heat, when setting the priority of the heat sources. Furthermore, the thermal energy control device 300 can take into consideration the loss (heat loss) that occurs during heat transfer between the heating requesting unit and the heat source, and can prioritize heat sources with relatively small heat loss and prioritize heat sources with relatively large heat loss.

[0042] In this way, by setting the priority taking heat loss into consideration, it is possible to efficiently heat the heating-requesting units, thereby suppressing power consumption in heat sources that intentionally generate heat and hastening the temperature rise of the heating-requesting units. Furthermore, the thermal energy control device 300 can prioritize heat sources that generate heat as a result of operation and prioritize heat sources that intentionally generate heat, and can prioritize heat sources with relatively small heat loss and prioritize heat sources with relatively large heat loss among multiple heat sources that generate heat as a result of operation or multiple heat sources that intentionally generate heat.

[0043] Furthermore, the thermal energy control device 300 (heat source determination unit 312) can limit the options for the heat source to be used as a heating heat source as the charging rate SOC of the heat source power supply battery (including the lithium ion battery 201) becomes lower. Specifically, when the charging rate SOC is lower than a predetermined value, that is, when there is little room for intentionally generating heat using the battery as a power source, the thermal energy control device 300 excludes, for example, heat sources that consume a relatively large amount of power relative to the amount of heat generated (in other words, the amount of heat that can be supplied to the heating requesting unit) from the options for the heating heat source. However, when the charging rate SOC is higher than a predetermined value, all heat sources can be selected as options. This can prevent the charging rate SOC from decreasing due to heating when the battery is at a low charging rate.

[0044] Furthermore, when the lithium ion battery 201 is being charged, the power from the external power supply can be used to generate heat in the heat source directly or via a power transformation process or the lithium ion battery 201. Furthermore, the power from the external power supply can be used for heating before charging begins, and surplus power during charging can also be used for heating.

[0045] Therefore, the thermal energy control device 300 (heat source determination unit 312) can set a priority to give priority to the use of a heat source that generates heat during operation when charging with a low-output AC charger, compared to when charging with a high-output DC charger, and can set a priority to give priority to the use of a heat source that intentionally generates heat when charging with a high-output DC charger, compared to when charging with a low-output AC charger. By giving priority to the use of a heat source that intentionally generates heat when charging with a DC charger, the temperature of the lithium-ion battery 201 can be raised to the required temperature in a short time, and stable high-output charging can be achieved.

[0046] By setting the priority as described above, it is possible to suppress power consumption while accelerating as much as possible the temperature rise of the lithium ion battery 201 and the electric axle 202. By raising the temperature of the lithium ion battery 201 to the required temperature (above 20°C), the capacity is restored and the lithium ion battery 201 can be used to the maximum extent, and by raising the temperature of the gear oil of the electric axle 202 to the required temperature (above 60°C), the power transmission efficiency is increased and electricity consumption is improved.

[0047] An example of setting a priority for each heat source is shown below. For example, in response to a request to heat the lithium ion battery 201 while the lithium ion battery 201 is being charged by an AC charger, the order of priority can be set from highest to lowest as follows: OBC 211, self-heating of the lithium ion battery 201, ECH 213, inverter 214, traction motor 212, and heat pump 215.

[0048] Furthermore, in response to a request to heat the lithium ion battery 201 in a situation other than charging using an AC charger (including a state of charging using a DC charger), the order of priority can be, from highest to lowest, self-heating of the lithium ion battery 201, the ECH 213, the inverter 214, the traction motor 212, and the heat pump 215. On the other hand, in response to a request to heat the electric axle 202 (gear oil) in a state in which the lithium ion battery 201 is being charged by an AC charger, the order of priority can be, from highest to lowest, OBC 211, the traction motor 212, the inverter 214, the ECH 213, and the heat pump 215.

[0049] Furthermore, when a request to heat the electric axle 202 (gear oil) is made while the lithium ion battery 201 is being charged by a DC charger, the order of priority can be, from highest to lowest, self-heating of the lithium ion battery 201, the traction motor 212, the inverter 214, the ECH 213, and the heat pump 215. Furthermore, when a request to heat the electric axle 202 (gear oil) is made while the power is on, the order of priority can be, from highest to lowest, the traction motor 212, the inverter 214, the heat pump 215, and the ECH 213.

[0050] The heat distribution unit 313 determines which of the lithium ion battery 201 and the electric axle 202 to prioritize in distributing heat in response to a heating request from the unit. Here, the heat distribution unit 313 determines the destination of the heat distribution priority for each state of the electric vehicle 200, which is classified by the temperature of the unit requesting heating, whether the power is on or off, whether charging is being performed, whether charging is performed using an AC charger or a DC charger, etc.

[0051] For example, when a request to heat the lithium ion battery 201 is made because the temperature of the lithium ion battery 201 is below 20° C. and the battery is being charged using an AC charger or a DC charger, the heat distribution unit 313 prioritizes heating the lithium ion battery 201 (in other words, it preferentially distributes heat generated by the heat source to the lithium ion battery 201), and if there is a surplus in the power supply, it also distributes heat to the heating of the electric axle 202. Furthermore, when the power is off and the battery is not being charged, the heat distribution unit 313 prioritizes heating the lithium ion battery 201 and distributes heat only to the lithium ion battery 201.

[0052] Next, the process of calculating the thermal efficiency used as a priority setting index, which is performed by the microcomputer 310, will be described with reference to the flowchart in Figure 5. In step S501, the microcomputer 310 determines whether a heating request has been issued in the heating requesting unit (lithium ion battery 201 or electric axle 202). If a heating request has not been issued in the heating requesting unit and it is not necessary to select a heat source to be used for heating the heating requesting unit, the microcomputer 310 ends the process without calculating the thermal efficiency of each heat source.

[0053] On the other hand, if a heating request has been generated in a heating requesting unit and a process for selecting a heat source to be used for heating the heating requesting unit is required, the microcomputer 310 proceeds to step S502. In step S502 (heat transfer estimated value calculation section), the microcomputer 310 calculates a heat transfer estimated value for each heat source.

[0054] The estimated heat transfer value is calculated as the estimated heat transfer value = heat generation amount x heat loss coefficient, and is the loss portion of the heat generation amount of each heat source. Here, the heat generation amount is the heat generation amount of a heat source that is currently generating heat or that will generate heat in response to a heat generation instruction (operation instruction). The heat loss coefficient is set for each heat source, taking into account the length of the piping connecting the heat-requesting unit and the heat source, the heat transfer coefficient, the outside temperature, the charging state, the charging output, etc.

[0055] Next, the microcomputer 310 proceeds to step S503 (thermal efficiency estimated value calculation section) and calculates an estimated thermal efficiency value (%) from the estimated heat transfer value obtained in step S502 and the heat generation amount of the heat source. Estimated thermal efficiency value = (heat generation amount - estimated heat transfer value) / heat generation amount × 100

[0056] In other words, the higher the estimated thermal efficiency, the more efficiently the heat generated by the heat source is provided to the heating-requesting unit, and conversely, the lower the estimated thermal efficiency, the greater the rate of heat loss, and the less heat generated by the heat source is provided to the heating-requesting unit. Therefore, the microcomputer 310 sets the priority of heat sources with high estimated thermal efficiency higher than the priority of heat sources with relatively low estimated thermal efficiency, and selects the heat source to be used to heat the heating-requesting unit in accordance with this priority, thereby enabling the heating-requesting unit to be heated efficiently.

[0057] 6 is a flowchart showing a process for selecting a heat source based on a thermal efficiency estimate, which is common to a heating request for the lithium ion battery 201 and a heating request for the electric axle 202. In step S511 (target heat amount calculation unit), the microcomputer 310 calculates a target heat amount (or a target temperature of the heating request unit), which is the amount of heat required to raise the temperature of the heating request unit (lithium ion battery 201 or electric axle 202) to the target temperature.

[0058] Next, in step S512, the microcomputer 310 executes heating control to supply the heat generated by the heat source with the highest estimated thermal efficiency to the heat-requesting unit. In other words, the microcomputer 310 sets the priority in descending order of the estimated thermal efficiency.

[0059] Here, if the heat source with the highest estimated thermal efficiency is the heat source that intentionally generates heat, microcomputer 310 outputs a heat generation instruction (operation instruction) to that heat source as heating control. Furthermore, since heating using a predetermined heat source is achieved by switching the heat medium circulation path using switching valve 406, heating control by microcomputer 310 includes control to switch the heat medium flow direction (in other words, the heat medium circulation path) by electronic control of switching valve 406.

[0060] The microcomputer 310 can prioritize heat sources that generate heat during operation and prioritize heat sources that intentionally generate heat, and can set priorities among multiple heat sources that generate heat during operation and / or multiple heat sources that intentionally generate heat based on the estimated thermal efficiency. The microcomputer 310 can also remove heat sources whose estimated thermal efficiency is equal to or less than a threshold (lower limit) from the priority order of heat sources used to heat heat-requesting units, and can prevent heat sources whose estimated thermal efficiency is equal to or less than the threshold (lower limit) from being used to heat heat-requesting units.

[0061] In step S513, the microcomputer 310 determines whether the amount of heat supplied from the heat source to the heat-requesting unit satisfies the target amount of heat (or whether the temperature of the heat-requesting unit has reached the target temperature). If the amount of heat supplied from the heat source to the heat-requesting unit satisfies the target amount of heat (or if the temperature of the heat-requesting unit has reached the target temperature), the microcomputer 310 ends this routine because there is no need to increase the heat source used to heat the heat-requesting unit.

[0062] On the other hand, if the amount of heat supplied from the heat source to the heat-requesting unit does not meet the target amount of heat (or if the temperature of the heat-requesting unit is lower than the target temperature), the microcomputer 310 proceeds to step S514. In step S514, the microcomputer 310 determines whether there is a heat source other than the heat source currently supplying heat to the heat-requesting unit that can supply heat to the heat-requesting unit, in other words, whether there is an additional heat source that can be used.

[0063] If the microcomputer 310 cannot add a heat source (in other words, increase the amount of heat supplied to the heat-requesting unit), it continues heating using the current heat source in step S515. On the other hand, if the microcomputer 310 can add a heat source, it executes heating control in step S516, adding heat generated by the heat source with the next highest estimated thermal efficiency, i.e., the heat source with the next highest priority, and supplies the added heat to the heat-requesting unit. Then, in the next step S517, if the amount of heat supplied from the heat source to the heat-requesting unit does not satisfy the target heat amount (or if the temperature of the heat-requesting unit is below the target temperature) and there is a heat source that can supply additional heat, the microcomputer 310 executes processing to gradually increase the number of heat sources used to heat the heat-requesting unit in descending order of estimated thermal efficiency (in other words, priority).

[0064] 7 is a flowchart showing the process of determining whether to prioritize heating of the lithium ion battery 201 or the electric axle 202. In step S521, the microcomputer 310 determines whether there is a request to heat the lithium ion battery 201. If there is no request to heat the lithium ion battery 201, the microcomputer 310 does not execute heating control of the lithium ion battery 201 or the electric axle 202 (gear oil) in step S522.

[0065] On the other hand, if there is a request to heat the lithium ion battery 201, the microcomputer 310 determines in step S523 whether there is a request to heat the electric axle 202 (gear oil). Here, if there is a request to heat the lithium ion battery 201 but there is no request to heat the electric axle 202 (gear oil), the microcomputer 310 performs heating control to heat only the lithium ion battery 201 in step S524.

[0066] On the other hand, if there is a request to heat the lithium ion battery 201 and also a request to heat the electric axle 202 (gear oil), the microcomputer 310 determines in step S525 whether the power supply to the electric vehicle 200 is on or off (in other words, whether the power switch is on or off). Then, when the power supply is on (the power switch is on), the microcomputer 310 determines in step S526 whether at least one of a first condition that the state of charge SOC is equal to or higher than a threshold value and a second condition that a charging connector of charging equipment for charging the lithium ion battery 201 is connected to the electric vehicle 200 is satisfied.

[0067] The threshold value of the SOC charging rate can be changed depending on the conditions of the outside temperature that affect the internal resistance, for example, when the outside temperature is low, the threshold value of the SOC charging rate can be changed to a higher value than when the outside temperature is high. Also, the connection determination of the charging connector is a process for determining the charging state when charging is performed via a wired connection, and in the charging state, heat is generated by a heat source using power supplied from an external power source.

[0068] However, charging of lithium ion battery 201 may be done by non-contact charging, and microcomputer 310 can detect, for example, a state in which an induced current flows through a power receiving coil of electric vehicle 200 as the charging state. Furthermore, heating using electric power from an external power source in the charging state includes cases in which electric power from the external power source is supplied to a heat source directly or via a power transformation process or lithium ion battery 201.

[0069] Here, if the first condition regarding the state of charge (SOC) and the second condition regarding the charging connector are not satisfied, i.e., if the state of charge (SOC) is below the threshold and the charging connector of the charging equipment is not connected to the electric vehicle 200 (if the vehicle is not in a charging state), the microcomputer 310 does not perform heating control of the lithium-ion battery 201 and the electric axle 202 (gear oil) in step S522. In other words, if the state of charge (SOC) is below the threshold, there is no room to use the power of the vehicle's onboard battery to heat the lithium-ion battery 201 and the electric axle 202 (gear oil). Furthermore, if the charging connector is not connected, the power supplied from the external power source cannot be used for heating. Therefore, the microcomputer 310 refrains from performing heating control for both the lithium-ion battery 201 and the electric axle 202 (gear oil).

[0070] On the other hand, if at least one of the first condition related to the state of charge SOC and the second condition related to the charging connector is satisfied, the microcomputer 310 determines that it is possible to secure the electric power used to heat the lithium ion battery 201 and the electric axle 202 (gear oil), and proceeds to step S527. In step S527, the microcomputer 310 performs heating control to heat the electric axle 202 (gear oil) and the lithium ion battery 201 in parallel in accordance with a setting that prioritizes heating of the electric axle 202 (gear oil) over heating of the lithium ion battery 201 (in other words, a setting that prioritizes heat distribution to the electric axle 202 over heat distribution to the lithium ion battery 201).

[0071] That is, in step S527 (heat distribution unit 313), microcomputer 310 prioritizes heating of one of the multiple heating request units. Note that in step S527, microcomputer 310 prioritizes heating of electric axle 202 (gear oil) over heating of lithium ion battery 201. However, if the charging connector of the charging equipment is connected to electric vehicle 200 and the processing of step S527 is performed, that is, if heating is performed using power supplied from an external power source, the priority order may change depending on the charging method, etc.

[0072] On the other hand, when electric vehicle 200 is in a power-off state (power switch is off), microcomputer 310 proceeds from step S525 to step S528. In step S528, microcomputer 310 determines whether or not the charging connector of the charging facility is connected to electric vehicle 200. If the charging connector is not connected to electric vehicle 200, microcomputer 310 proceeds to step S524 and performs heating control to heat only lithium ion battery 201.

[0073] On the other hand, if the charging connector is connected to electric vehicle 200 (in other words, if the vehicle is in a charging state), microcomputer 310 proceeds to step S529 and determines whether the amount of power supplied from the external power source for charging is equal to or greater than the set value and whether there is a surplus of power to be allocated to heating electric axle 202 (gear oil) and lithium ion battery 201. Here, if the amount of power supplied from the external power source is equal to or greater than the set value and there is a surplus of power, microcomputer 310 proceeds to step S530 and heats electric axle 202 (gear oil) and lithium ion battery 201 in parallel in accordance with a setting that prioritizes heating of lithium ion battery 201 over heating of electric axle 202 (gear oil).

[0074] That is, in step S530 (heat distribution unit 313), microcomputer 310 prioritizes heating of one of the multiple heating request units. Note that in step S530, microcomputer 310 prioritizes heating of lithium ion battery 201 over heating of electric axle 202 (gear oil), but the order of priority may vary depending on the charging method, etc.

[0075] 8 is a flowchart showing the heat source selection process based on the charging method of the lithium ion battery 201. In step S541, the microcomputer 310 determines whether a heating request has been issued by the heating requesting unit (lithium ion battery 201 or electric axle 202). If no heating request has been issued by the heating requesting unit, the microcomputer 310 proceeds to step S542 and does not perform heating control.

[0076] On the other hand, if there is a heating request from the heating requesting unit, microcomputer 310 proceeds to step S543 and determines whether or not a charging connector of charging equipment for charging lithium ion battery 201 is connected to electric vehicle 200. As described above, determining whether the charging connector is connected is a process for determining the charging state when charging is performed via a wired connection, and charging may also be performed by contactless charging.

[0077] If the charging connector is not connected to the electric vehicle 200 (in other words, if the lithium ion battery 201 is not being charged), the microcomputer 310 proceeds to step S544. Then, in step S544, the microcomputer 310 selects a heat source to use for heating in accordance with the heat source priority determined for each heating requesting unit (lithium ion battery 201, electric axle 202).

[0078] On the other hand, if the charging connector is connected to electric vehicle 200 (in other words, if charging of lithium ion battery 201 is being performed), microcomputer 310 proceeds to step S545. In step S545, microcomputer 310 determines the charging method for charging lithium ion battery 201.

[0079] Specifically, in step S545, microcomputer 310 determines whether lithium ion battery 201 is to be charged by a charging method in which the charging time is set to be equal to or less than a threshold, for example, rapid charging using a DC charger. In other words, in step S545, microcomputer 310 determines the specifications or supply output of the charging equipment used to charge lithium ion battery 201.

[0080] If the lithium ion battery 201 is charged by charging (for example, rapid charging using a DC charger) with a charging time set to a threshold value (for example, 30 minutes) or less, the microcomputer 310 proceeds to step S546. In step S546, the microcomputer 310 sets a priority order for the heat sources so that a heat source that intentionally generates heat is used preferentially among the multiple heat sources.

[0081] In charging where the charging time is set to be equal to or less than a threshold, high-power charging is possible by heating the lithium-ion battery 201. Therefore, by using a heat source that intentionally generates heat, such as the ECH 213, the heating-requesting unit can be heated to the required temperature in a short time, thereby realizing stable high-power charging.

[0082] On the other hand, if the charging time is not set to be equal to or less than the threshold, such as low-power charging using an AC charger (normal charging, home charging), the microcomputer 310 proceeds to step S547. In step S547, the microcomputer 310 sets a priority order for the heat sources so that a heat source that generates heat as it operates, in other words, a heat source that generates heat unintentionally, is used preferentially. Since low-power charging using an AC charger is expected to take a long time, the power consumption for heating can be reduced by preferentially using a heat source that generates heat (waste heat) as it operates, such as the OBC 211.

[0083] The technical ideas described in the above embodiments can be used in appropriate combinations as long as no contradictions arise. Furthermore, although the contents of the present invention have been specifically described with reference to preferred embodiments, it is obvious that a person skilled in the art can adopt various modified embodiments based on the basic technical ideas and teachings of the present invention.

[0084] For example, the heat sources are not limited to the OBC 211, the traction motor 212, the lithium ion battery 201, the ECH 213, the inverter 214, and the heat pump 215. For example, if the electric vehicle 200 is equipped with a combustion heater, the combustion heater can be used as a heat source (a heat source that intentionally generates heat). Furthermore, when the amount of heat supplied is insufficient for the amount of heat requested, the process is not limited to increasing the heat sources step by step one by one. For example, the amount of heat that can be supplied from each heat source to the heating requesting unit can be estimated, and the estimated amounts of heat can be added in descending order of priority, so that a plurality of heat sources whose total amount of heat is close to the requested amount of heat can be selected at one time as heating heat sources.

[0085] Furthermore, the heating request unit is not limited to the lithium ion battery 201 or the electric axle 202, and for example, an air conditioning unit or a heat storage unit can be used as the heating request unit, and the heat source used for heating can be selected according to priority. Furthermore, the vehicle is not limited to the electric vehicle 200, and may be a PHEV (plug-in hybrid vehicle) or the like.

[0086] Furthermore, when the units requiring heating are the lithium ion battery 201, the electric axle 202, the air conditioning unit, and the heat storage unit, the order of priority for heating can be, from highest to lowest, the lithium ion battery 201, the electric axle 202, the air conditioning unit, and the heat storage unit. Note that, when the electric vehicle 200 is traveling, the heating request for the electric axle 202 can be given priority over the lithium ion battery 201.

[0087] 100...thermal energy control system, 200...electric vehicle, 201...lithium ion battery (driving battery system), 202...electric axle (axle system), 211...OBC, 212...driving motor, 213...ECH, 214...inverter, 215...heat pump, 300...thermal energy control device, 310...microcomputer, 311...required heat quantity determination unit, 312...heat source determination unit, 313...heat quantity distribution unit

Claims

1. A thermal energy control system mounted on a vehicle, comprising: a plurality of heat sources; at least one heating request unit that generates a heating request according to conditions; and a heat source determination unit that determines which of the plurality of heat sources to use for heating the heating request unit, the heat source determination unit setting a priority for each of the plurality of heat sources in response to a heating request generated by the heating request unit, and selecting the heating heat source from the plurality of heat sources based on the priority.

2. A thermal energy control system as described in claim 1, wherein the heat source determination unit, in setting the priority, prioritizes those heat sources that generate heat in conjunction with operation among the plurality of heat sources and prioritizes those heat sources that intentionally generate heat among the plurality of heat sources.

3. A thermal energy control system as described in claim 1, wherein the heat demanding unit and the plurality of heat sources are connected by piping through which a heat medium flows, and at least a driving battery system of the vehicle and an axle system of the vehicle are connected to the piping as the heat demanding units, and the thermal energy control system is configured to be able to supply the heat medium to the driving battery system and the axle system individually.

4. A thermal energy control system according to claim 1, wherein the heat source determination unit changes the priority according to the condition of the vehicle.

5. A thermal energy control system according to claim 1, wherein the heat source determination unit changes the priority in accordance with a loss during heat transfer between the heating request unit and the heat source.

6. A thermal energy control system according to claim 1, wherein the heat source determination unit limits the options for the heat source to be used as the heating heat source as the charging rate of the battery installed in the vehicle becomes lower.

7. A thermal energy control system as described in claim 1, wherein, when the heat source determination unit detects a failure of the heat source, it removes the heat source for which the failure has been detected from the options for the heating heat source, and selects the heat source with the next highest priority after the heat source that has been removed from the options as the heating heat source.

8. A thermal energy control system as described in claim 1, wherein the heat source determination unit generates heat in at least one of the plurality of heat sources using power supplied by an external power source when a battery mounted on the vehicle is charged by the external power source.

9. A thermal energy control system as claimed in claim 1, further comprising a heat distribution unit that prioritizes heating of the battery when the battery mounted on the vehicle as the heating request unit is being charged by a DC charger, compared to when the battery is being charged by an AC charger.

10. A thermal energy control system according to claim 1, further comprising a heat quantity distribution unit that, when there are a plurality of heating requesting units, gives priority to heating one of the plurality of heating requesting units.

11. A thermal energy control method executed by a control device mounted on a vehicle, the vehicle having a plurality of heat sources and at least one heating request unit that generates a heating request depending on conditions, the thermal energy control method comprising: setting a priority for each of the plurality of heat sources in response to a heating request generated by the heating request unit; selecting a heating heat source from the plurality of heat sources to be used to heat the heating request unit based on the priority; and heating the heating request unit with heat generated by the heating heat source.

12. A thermal energy control device mounted on a vehicle, the vehicle having a plurality of heat sources and at least one heating request unit that generates a heating request according to conditions, the thermal energy control device being configured to: set a priority for each of the plurality of heat sources in response to a heating request generated by the heating request unit; select a heating heat source from the plurality of heat sources to be used to heat the heating request unit based on the priority; and heat the heating request unit with the heat generated by the heating heat source.

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