JP6790693B2 - In-vehicle battery charging system - Google Patents

Description

The present invention relates to a charging system for an in-vehicle battery, and more particularly to a charging system including a heater for raising the temperature of the battery.

Vehicles that use a rotating electric machine as a drive source, such as electric vehicles and hybrid vehicles, are equipped with a battery module that is a DC power source. A plurality of battery cells (cells) are stacked and connected to the battery module.

Among electric vehicles, hybrid vehicles, and the like, vehicles capable of external charging such as plug-in charging and non-contact charging may carry out the external charging process in two stages. For example, first, a first charging mode (CP1) in which charging is performed with a relatively large amount of power is executed. Next, a second charging mode (CP2) for charging with relatively low power is executed. The second charging mode is also called push-in charging, and charging is performed while suppressing the temperature rise and overvoltage associated with the decrease in charging efficiency by reducing the charging power at the time of high SOC in which the charging efficiency is relatively decreased.

Further, it is known that the charge / discharge characteristics of a battery module affect its temperature (battery temperature). For example, the lower the temperature, the lower the charge / discharge efficiency of the battery module. In order to obtain sufficient charging efficiency and discharging efficiency, the battery module is heated (heated) by using a heater during external charging.

For example, in Patent Document 1, the temperature rise is executed at the time of external charging in order to obtain a desired charging efficiency. That is, at the time of external charging, the external power is distributed to the charging power (charging power) and the temperature raising power (heating power). In this distribution, in the first charging mode, the change in the charging time (charging efficiency) when the ratio of the rising power to the external power (maximum power) is changed is obtained in advance, and the charging time is the shortest, in other words. And the ratio of the heating power that maximizes the charging efficiency is sought. In the second charging mode, the charging power is set to a fixed value, and the remaining power (maximum power-charging power) is assigned to the heating power.

Further, in Patent Document 2, the temperature is raised at the time of external charging in order to obtain a desired discharge efficiency. That is, the temperature of the battery module is raised during external charging in order to raise the discharge efficiency of the battery module at the completion of external charging to a level that enables EV traveling. Specifically, the temperature rise time is obtained from the measured value of the battery temperature and the target temperature with the temperature rise power as a fixed value. Further, the temperature rise start time is set retroactively by the temperature rise time from the set time of the charge completion time timer.

JP-A-2015-159633 Japanese Unexamined Patent Publication No. 2016-51590

By the way, when the first charging mode and the second charging mode are carried out in the external charging process, the heating power is determined based on the charging efficiency in the first charging mode. Since the temperature is raised based on the charging efficiency, the battery module may not be heated until the desired discharge characteristics are obtained at the end of the first charging mode. Therefore, it is conceivable to raise the temperature of the battery module to the target temperature based on the discharge characteristics in the second charging mode, but when the second charging mode is for a short period of time, the temperature rise is not in time and the temperature of the second charging mode At the end, the temperature of the battery module may not reach the target temperature based on the discharge characteristics. Therefore, an object of the present invention is to provide an in-vehicle battery charging system capable of raising the temperature of a battery module to a target temperature based on discharge characteristics by the time the external charging is completed.

The present invention relates to an in-vehicle battery charging system capable of external charging in which a battery mounted on a vehicle is charged from an external power source outside the vehicle. The charging system includes a heater that raises the temperature of the battery, and a control unit that manages the charging of the battery and controls the heater. The control unit has a first charging mode in which the battery is charged with a relatively large power during the external charging, and a second charging mode in which the battery is charged with a relatively small power after the first charging mode. And execute. Further, the control unit includes a first power distribution unit, a second power distribution unit, and an adjustment unit. In the first charging mode, the first power distribution unit obtains the external power supplied from the external power source from the charging efficiency according to the temperature of the battery, and supplies the first heating power to the heater. It is allocated to the first charging power to the battery. In the second charging mode, the second power distribution unit determines the second charging mode from the maximum heating power obtained by subtracting the predetermined second charging power from the external power and the execution period of the second charging mode. The maximum amount of temperature rise in. The adjusting unit has a minimum battery estimated temperature at the time of completion of the first charging mode based on the first heating power, which is obtained by subtracting the maximum heating amount from the discharge target temperature obtained from the discharge efficiency according to the battery temperature. When the temperature is lower than the reference temperature, the additional heating power corresponding to the temperature difference between the minimum reference temperature and the estimated battery temperature is added to the first heating power, and the addition is added to the first heating power after the addition. The first charging power is reduced so that the sum of the first charging power is equal to or less than the external power.

According to the present invention, the battery module can be heated to a target temperature based on the discharge characteristics by the time the external charging is completed.

It is a figure which illustrates the structure of the charge system of the vehicle-mounted battery which concerns on this embodiment, and the vehicle equipped with this. It is a figure which illustrates the functional block of a control part. It is a figure which illustrates the external charge flow with a temperature rise. It is a figure which illustrates the charge efficiency map of the 1st charge mode (CP1). It is a figure which illustrates the power distribution of the external charge. It is a figure which shows another example (the discharge target temperature not reached example) of the power distribution of external charge. It is a figure explaining the shift operation of the charge efficiency map. It is a figure which shows another example (CP1 adjustment example) of power distribution of external charge. It is a figure which shows another example of the external charge flow with a temperature rise. It is a figure which illustrates the power distribution of the external charge (the discharge target temperature not reached example) when another example of the external charge flow with a temperature rise is executed.

FIG. 1 illustrates the configuration of an in-vehicle battery charging system according to the present embodiment and a vehicle equipped with the system. In addition, in order to simplify the illustration, in FIG. 1, the configuration which is not related to the charging system according to the present embodiment is omitted as appropriate. The arrow line in FIG. 1 represents a signal line.

The main battery 10 is composed of a secondary battery such as a nickel hydrogen or lithium ion battery. For example, the main battery 10 is composed of a stack (laminated body) in which a plurality of battery cells (cells) of about 1 to 5 V are laminated.

The DC power output from the main battery 10 is boosted by the buck-boost DC / DC converter 12. The boosted DC power is orthogonally converted by the inverter 14. The converted AC power is supplied to at least one of the rotary electric machines MG1 and MG2. Since the power transmission path in which power is transmitted from the rotary electric machines MG1 and MG2 to the wheels 18 via the power distribution mechanism 16 is known, the description thereof will be omitted here.

Further, a branch electric circuit is provided which is branched from the electric circuit connecting the main battery 10 and the buck-boost DC / DC converter 12 and is connected to the step-down DC / DC converter 20. The high-voltage power of the main battery 10 is stepped down by the step-down DC / DC converter 20 and supplied to the sub-battery 22, the control unit 24, the battery heater 26, and other accessories.

Further, in the plug-in hybrid vehicle illustrated in FIG. 1, the main battery 10 can be charged (external charging or plug-in charging) from the AC power source 30 (external power source) outside the vehicle. External charging is controlled by the charging system according to this embodiment. The AC power supply 30 is, for example, a household single-phase 100V AC power supply or a single-phase 200V AC power supply.

For external charging, the connector 32 (plug) of the AC power supply 30 is connected to the connector 34 (inlet) provided in the vehicle. When external charging is started, that is, when the charging relay CHR is switched from the off state to the on state by the control unit 24, the AC power supplied from the AC power supply 30 is AC / DC converted and boosted by the charger 38, and after conversion and boosting. DC power is supplied to the main battery 10. Of the DC power after orthogonal conversion and boosting by the charger 38, the maximum DC power that can be obtained by the AC power supply 30 and the charger 38 may be treated as external power Ps below. The external power Ps can be obtained from, for example, the output voltage value and the output current value sent from the charger 38 to the control unit 24.

The external charging process according to the present embodiment is executed in two stages of a first charging mode (CP1) and a second charging mode (CP2) executed thereafter. In the first charging mode, charging is performed with a relatively large amount of power with the aim of shortening the charging time. Next, in the second charging mode, when the charging efficiency is relatively low at high SOC, charging is performed with relatively low power in order to suppress the temperature rise and overvoltage accompanying the decrease in the charging efficiency. The second charging mode is also called push charging.

Further, as will be described later, when the main battery 10 needs to be heated (heated) during external charging, the battery heater 26 is used. That is, when the system main relay SMR and the heater relay 28 are switched from the off state to the on state by the control unit 24, a part of the external power supplied from the AC power supply 30 is stepped down by the step-down DC / DC converter 20 and the battery heater. It is supplied to 26.

For example, when driving a vehicle after external charging, a so-called EV driving mode in which the vehicle is driven only by the power of the main battery 10, that is, the power of the rotary electric machines MG1 and MG2 (without using the power of the internal combustion engine 46) is possible. The discharge target temperature Td is set based on the discharge efficiency of the main battery 10. The discharge efficiency changes according to the battery temperature Tb. The discharge target temperature Td may be included in, for example, the temperature zone of the main battery 10 where the discharge power limit Wout is the loosest, and is set to, for example, 25 ° C. The battery heater 26 is appropriately used so that the temperature Tb (battery temperature) of the main battery 10 reaches the discharge target temperature Td when the external charging is completed.

Further, in addition to the discharge target temperature Td, the charge target temperature Tc is set for the main battery 10. The charging target temperature Tc is determined based on the charging efficiency of the in-battery 10. The charging efficiency changes according to the battery temperature Tb as well as the discharging efficiency. The charging target temperature Tc may be included in, for example, the temperature zone of the main battery 10 where the charging power limit Win is the loosest. For example, the charging target temperature Tc is set to 5 ° C. As described above, the charging target temperature Tc is generally set to a value lower than the discharging target temperature Td (Tc <Td). During the external charging, the battery heater 26 is appropriately used so that the main battery 10 has a charging target temperature Tc or higher.

The charging system according to the present embodiment includes a control unit 24 and a battery heater 26. The control unit 24 manages the charge / discharge of the main battery 10 and controls the battery heater 26. The control unit 24 is composed of, for example, a computer, and includes a CPU 42 and a storage unit 44, which are arithmetic circuits. The storage unit 44 includes a volatile memory such as SRAM and a non-volatile memory such as ROM and a hard disk. The storage unit 44 stores various parameters related to the external charge flow with temperature rise, such as a program for executing the external charge flow with temperature rise, which will be described later, and a target SOC.

By executing the external charging program with temperature rise stored in the storage unit 44, the functional unit shown in FIG. 2 is generated in the control unit 24. This functional unit is generated by allocating resources such as the CPU 42 and the storage unit 44, respectively, and is illustrated as virtually independent functional blocks. As this functional block, the control unit 24 includes an SOC calculation unit 50, a CP1 power distribution calculation unit 52 (first power distribution unit), a CP1 charge efficiency map database 54, and a CP2 power distribution calculation unit 56 (second power distribution unit). It includes a CP2 charging condition database 58, a power distribution adjusting unit 60 (adjusting unit), and a charging power control unit 62.

The SOC calculation unit 50 calculates the SOC of the main battery 10 by monitoring the current supplied to the main battery 10 via the current sensor 37 and monitoring the voltage change of the main battery 10 via the voltage sensor 39. To do.

A plurality of charge efficiency maps are stored in the CP1 charge efficiency map database 54. FIG. 4 illustrates a charging efficiency map. When the main battery 10 is in a low temperature state, the charging efficiency is lowered. Therefore, it is conceivable to allocate a part of the external power supplied from the AC power source 30 to the battery heater 26 to charge the main battery 10 while raising the temperature.

At this time, if the ratio of the electric power (heating power) allocated to the battery heater 26 becomes excessively large, the allocation to the charging electric power is reduced, and it takes time to charge the battery. On the other hand, if the power allocated to the battery heater 26 (heating power) is excessively reduced, the temperature of the main battery 10 is not raised, so that the charging efficiency is lowered and charging takes time. Therefore, in order to obtain the best balance between the charging power and the heating power, the charging efficiency map as shown in FIG. 4 is used. The charging efficiency map can be obtained in advance by actual measurement, simulation, or the like.

In the graph of FIG. 4, the horizontal axis represents the ratio of the rising power to the external power (maximum power), and the vertical axis represents the charging time. A plurality of types of such graphs may be stored in the CP1 charge efficiency map database 54 for each battery temperature Tb and SOC. Further, when the battery temperature Tb is equal to or higher than the charging target temperature Tc described later, a map in which the first heating power Pw_cp1 is set to 0 and all external power is allocated to the charging power may be stored in the CP1 charging efficiency map database 54. ..

In the first charging mode (CP1), the CP1 power distribution calculation unit 52 uses the external power Ps as the first charging power Pc_cp1 supplied to the main battery 10 and the first heating power Pw_cp1 supplied to the battery heater 26. Allocate to. The CP1 charge efficiency map database 54 is used for allocation. Further, the execution time t_cp1 of the first charging mode is calculated based on the allocated first charging power Pc_cp1 and the first target SOC. Details of the CP1 power distribution calculation unit 52 will be described later.

The charging conditions of the second charging mode (CP2) are stored in the CP2 charging condition database 58. Specifically, the first target SOC that serves as a reference for switching between the first charging mode and the second charging mode and the second target SOC that serves as a completion reference for the second charging mode, that is, indicating a fully charged state, are stored. Further, the second charging power Pc_cp2 in the second charging mode is stored as a fixed value.

In the second charging mode (CP2), the CP2 power distribution calculation unit 56 uses the external power Ps as the second charging power Pc_cp2 supplied to the main battery 10 and the second heating power Pw_cp2 supplied to the battery heater 26. Allocate to. As described above, since the second charging power Pc_cp2 is a fixed value, a percentage of the power obtained by subtracting the second charging power Pc_cp2 from the external power Ps is allocated to the second heating power Pw_cp2. As will be described later, the CP2 power distribution calculation unit 56 obtains the second temperature rising power Pw_cp2 based on the estimated value of the battery temperature Tb (t1) at the completion of the first charging mode (CP1) and the discharge target temperature Td. ..

The power distribution adjusting unit 60 includes a first charging power Pc_cp1 and a first heating power Pw_cp1 calculated by the CP1 power distribution calculation unit 52, and a second charging power Pc_cp2 and a second ascending power calculated by the CP2 power distribution calculation unit 56. The thermal power Pw_cp2 is adjusted respectively. By making this adjustment as described later, the battery temperature Tb (t2) can be raised to the discharge target temperature Td at t2 when the second charging mode (CP2) is completed.

The charging power control unit 62 includes a first charging power Pc_cp1, a first heating power Pw_cp1, a first charging time t_cp1, a second charging power Pc_cp2, and a second heating power Pw_cp2 adjusted by the power distribution adjusting unit 60. , And the charging power of the main battery 10 and the power supplied to the battery heater 26 (heating power) are controlled based on the second charging time t_cp2. For example, by controlling the duty ratio of the step-down DC / DC converter 20 and the charger 38, the above power control is performed.

FIG. 3 illustrates an external charging flowchart with temperature rise according to the present embodiment. After the vehicle start switch (not shown) is turned off by the vehicle user and the system main relay SMR (see FIG. 1) switches from the connected state to the disconnected state, the connector 32 (plug) of the AC power supply 30 is the vehicle connector. Connected to 34 (inlet) (plug-in). At this time, a connection command (connector connection command) is transmitted from the connector 34 to the power distribution adjustment unit 60 of the control unit 24, and the flow of FIG. 3 is activated.

The power distribution adjustment unit 60 acquires the temperature Tb (t0) (battery temperature) of the main battery 10 at the time t0 when the connection command is received from the battery temperature sensor 48. Further, it is determined whether or not the battery temperature Tb (t0) is less than the discharge target temperature Td (S10).

When the battery temperature Tb (t0) is equal to or higher than the discharge target temperature Td in step S10, the charging target temperature Tb (<Td) is also exceeded as described above, so that the temperature of the main battery 10 is raised during external charging. There is no need. Therefore, when the battery temperature Tb (t0) is equal to or higher than the discharge target temperature Td in step S10, this flow ends, and for example, the entire amount of the external power Ps is allocated to the charging power.

When Tb (t0) <Td in step S10, the power distribution adjusting unit 60 tells the CP1 power distribution calculation unit 52 that the first charging power Pc_cp1 and the first heating power in CP1 (first charging mode). A calculation instruction for calculating Pw_cp1 is transmitted (S12).

The CP1 power distribution calculation unit 52 acquires the battery temperature Tb (t0) at the time t0 when the connection command is received from the battery temperature sensor 48. Alternatively, the battery temperature Tb (t0) is acquired from the power distribution adjustment unit 60.

Further, the CP1 power distribution calculation unit 52 acquires the SOC (t0) of the main battery 10 at the connection command reception time t0 from the SOC calculation unit 50.

The CP1 power distribution calculation unit 52 acquires a charge efficiency map corresponding to the battery temperatures Tb (t0) and SOC (t0) from the CP1 charge efficiency map database 54. From the charging efficiency map shown in FIG. 4, the ratio Rcp1 of the heating power / external power that minimizes the charging time (vertical axis) is obtained.

Further, the CP1 power distribution calculation unit 52 obtains the rising power Pw_cp1 by multiplying the obtained ratio Rcp1 of the rising power / external power by the external power Ps. Further, the charging power Pc_cp1 is obtained by subtracting the heating power Pw_cp1 from the external power Ps. Further, the first charging time t_cp1 is obtained from the charging efficiency map. The heating power Pw_cp1, the charging power Pc_cp1, and the first charging time t_cp1 are transmitted to the power distribution adjusting unit 60.

Next, the power distribution adjusting unit 60 transmits a calculation instruction for calculating the second charging time t_cp2 in the CP2 (second charging mode) to the CP2 power distribution calculation unit 56 (S14).

The CP2 power distribution calculation unit 56 refers to the CP2 charging condition database 58 and serves as a completion reference for the first target SOC and the second charging mode, which are criteria for switching between the first charging mode and the second charging mode, that is, fully charged. The second target SOC indicating the state and the second charging power Pc_cp2 in the second charging mode are called. The second charging time t_cp2 is obtained from the SOC difference (ΔSOC) between the first target SOC and the second target SOC and the second charging power Pc_cp2. The second charging power Pc_cp2 and the second charging time t_cp2 are transmitted to the power distribution adjusting unit 60 together with the external power Ps.

Further, the CP2 power distribution calculation unit 56 obtains the maximum heating power Pw_cp2max obtained by subtracting the second charging power Pc_cp2 from the external power Ps. In addition, the CP2 power distribution calculation unit 56 obtains the maximum temperature rise amount ΔTmax in the second charging time from the maximum temperature rising power Pw_cp2max and the second charging time t_cp2 (S16).

First, the amount of heat [J] can be obtained by multiplying the maximum heating power Pw_cp2max by the second charging time t_cp2. By dividing this amount of heat [J] by the mass of the main battery 10 and the specific heat, the maximum amount of temperature rise ΔTmax can be obtained. The mass and specific heat of the main battery 10 are obtained in advance and stored in the storage unit 44 of the control unit 24. The maximum temperature rise amount ΔTmax is transmitted to the power distribution adjustment unit 60.

The power distribution adjusting unit 60 subtracts the maximum temperature rise amount ΔTmax from the discharge target temperature Td stored in the storage unit 44, and sets the obtained value as Tb (t1 *) (S18). This is the reference value (minimum reference temperature) of the battery temperature Tb at t1 when the first charging mode is completed.

Further, the power distribution adjusting unit 60 estimates the battery temperature Tb (t1) at the time when the first charging mode (CP1) is completed from the temperature rising power Pw_cp1 and the first charging time t_cp1 acquired from the CP1 power distribution calculation unit 52. (S20). For example, the amount of heat [J] can be obtained by multiplying the heating power Pw_cp1 by the first charging time t_cp1. By dividing this amount of heat [J] by the mass of the main battery 10 and the specific heat, the first amount of temperature rise ΔTcp1 can be obtained. Further, by adding the first temperature rising amount ΔTcp1 to the battery temperature Tb (t0) at the start time of the first charging mode t0, the estimated battery temperature Tb (t1) at the time t1 when the first charging mode (CP1) is completed can be obtained.

The power distribution adjustment unit 60 determines whether or not the estimated battery temperature Tb (t1) at t1 at the completion of the first charging mode is less than the minimum reference temperature Tb (t1 *) at the same point (Tb (t1 *)> Tb (t1)). (S22). That is, the battery estimated temperature Tb (t1) at the time of completion of the first charging mode t1 based on the first heating power Pw_cp1 is the minimum obtained by subtracting the maximum temperature rise amount ΔTmax from the discharge target temperature Td obtained from the discharge efficiency of the main battery 10. It is determined whether or not the temperature is less than the reference temperature Tb (t1 *).

As shown in FIG. 5, when the estimated battery temperature Tb (t1) (= Tc) is equal to or higher than the minimum reference temperature Tb (t1 *), the main battery is at least the maximum temperature rise amount ΔTmax in the second charging mode (CP2). If the temperature of 10 is raised, the battery temperature Tb reaches the discharge target temperature Td at t2 when the second charging mode is completed. Therefore, the power distribution adjusting unit 60 sets the first heating power Pw_cp1, the first charging power Pc_cp1, and the first charging time t_cp1 obtained in step S12 as definite values for the CP1 power distribution calculation unit 52. It is transmitted to the charging power control unit 62 (S24).

Next, the power distribution adjustment unit 60 transmits the discharge target temperature Td and the battery estimated temperature Tb (t1) at the time when the first charge mode is completed t1 to the CP2 power distribution calculation unit 56. Further, the power distribution adjusting unit 60 transmits a calculation instruction to obtain the second temperature rising power Pw_cp2 based on the discharge target temperature Td and the battery estimated temperature Tb (t1) to the CP2 power distribution calculation unit 56.

With reference to FIG. 5, the CP2 power distribution calculation unit 56 obtains the temperature difference ΔTdb obtained by subtracting the estimated battery temperature Tb (t1) (= Tc) from the discharge target temperature Td. The amount of heat [J] is obtained by multiplying this by the mass of the main battery 10 and the specific heat. The heating power Pw_cp2 [W] can be obtained by dividing the amount of heat [J] by the second charging time t_cp2 (S26). The second heating power Pw_cp2, the second charging power Pc_cp2, and the second charging time t_cp2 are sent to the charging power control unit 62.

As described above, in the charging power control unit 62, the determined first heating power Pw_cp1, the first charging power Pc_cp1, the first charging time t_cp1, the second heating power Pw_cp2, the second charging power Pc_cp2, and , This flow ends when the second charging time t_cp2 is sent. The charging power control unit 62 controls and manages the external charging process by performing PWM control of the charger 38 and the step-down DC / DC converter 20 based on these parameters.

Returning to step S22, the estimated battery temperature Tb (t1) (= Tc) at t1 when the first charging mode is completed is less than the minimum reference temperature Tb (t1 *) at the same point (Tb (t1 *)> Tb (t1). )) In that case, as shown in FIG. 6, there is an insufficient temperature rise.

This means that even if the main battery 10 is heated at the maximum temperature rise amount ΔTmax in the second charge mode (CP2), the battery temperature Tb is lower than the discharge target temperature Td at t2 when the second charge mode is completed. Become. Therefore, the power distribution adjustment unit 60 transmits a calculation instruction to the CP1 power distribution calculation unit 52 to recalculate the first heating power Pw_cp1, the first charging power Pc_cp1, and the first charging time t_cp1 (S28). ..

In this recalculation process, basically, the additional heating power corresponding to the temperature difference between the minimum reference temperature Tb (t1 *) and the estimated battery temperature Tb (t1) is added to the first heating power Pw_cp1. First, the CP1 power distribution calculation unit 52 acquires the CP1 charge efficiency map used in step S12, that is, the charge efficiency map corresponding to the battery temperatures Tb (t0) and SOC (t0) from the CP1 charge efficiency map database 54. ..

Further, as shown in FIG. 7, the CP1 power distribution calculation unit 52 increases the value of the ratio Rcp1 of the temperature rising power / external power by a predetermined amount (shifts to an increment on the horizontal axis). For example, the ratio Rcp1 of the heating power / external power is shifted to the plus side in 1% increments. With the above shift, the ratio of rising power / external power Rcp1'and the first charging time t_cp1' can be obtained.

The CP1 power distribution calculation unit 52 obtains the temperature-increasing power Pw_cp1'by multiplying the changed ratio Rcp1'of the temperature-increasing power / external power by the external power Ps. Further, as shown in FIG. 8, the charging power Pc_cp1'is obtained by subtracting the raising power Pw_cp1'from the external power Ps.

From Rcp1 <Rcp1', the heating power becomes Pw_cp1 <Pw_cp1'. Further, the charging power for competing the temperature rising power and the external power Ps is Pc_cp1> Pc_cp1'. That is, the charging power can be reduced by the increase in the heating power. The first charging time t_cp1', the heating power Pw_cp1', and the charging power Pc_cp1' are sent to the power distribution adjusting unit 60.

The power distribution adjustment unit 60 obtains the estimated battery temperature Tb (t1') at the time when the first charging mode is completed t1 from the rising power Pw_cp1'and the first charging time t_cp1' (S30). For example, the amount of heat [J] can be obtained by multiplying the heating power Pw_cp1'and the first charging time t_cp1'. By dividing this amount of heat [J] by the mass of the main battery 10 and the specific heat, the first amount of temperature rise ΔTcp1'is obtained. Further, when the first heating amount ΔTcp1'is added to the battery temperature Tb (t0) at the start time of the first charging mode t0, the estimated battery temperature Tb (t1') at the time t1'completion of the first charging mode (CP1) is obtained. Be done.

The power distribution adjustment unit 60 determines whether or not the estimated battery temperature Tb (t1') is less than the minimum reference temperature Tb (t1 *) (Tb (t1 *)> Tb (t1')) (S32). If Tb (t1 *)> Tb (t1'), the process returns to step S28, and the CP1 power distribution calculation unit 52 is again calculated for the first charging time t_cp1', the heating power Pw_cp1', and the charging power Pc_cp1'. To instruct.

In step S32, when the estimated battery temperature Tb (t1') is equal to or higher than the minimum reference temperature Tb (t1 *), the power distribution adjustment unit 60 obtains the CP1 power distribution calculation unit 52 in step S28. , The first heating power Pw_cp1', the first charging power Pc_cp1', and the first charging time t_cp1' are set as definite values and transmitted to the charging power control unit 62 (S34).

Next, the power distribution adjustment unit 60 transmits the discharge target temperature Td and the battery estimated temperature Tb (t1') at the time when the first charge mode is completed t1'to the CP2 power distribution calculation unit 56. Further, the power distribution adjustment unit 60 transmits to the CP2 power distribution calculation unit 56 a calculation instruction to obtain the second temperature rising power Pw_cp2'based on the temperature difference ΔTdb of the discharge target temperature Td and the battery estimated temperature Tb (t1'). To do.

With reference to FIG. 5, the temperature difference ΔTdb obtained by subtracting the estimated battery temperature Tb (t1) (= Tc) from the discharge target temperature Td is obtained. The amount of heat [J] is obtained by multiplying this by the mass of the main battery 10 and the specific heat. The heating power Pw_cp2'[W] can be obtained by dividing the amount of heat [J] by the second charging time t_cp2 (S36). The second heating power Pw_cp2', the second charging power Pc_cp2, and the second charging time t_cp2 are sent to the charging power control unit 62.

The charging power control unit 62 determines the first heating power Pw_cp1', the first charging power Pc_cp1', the first charging time t_cp1', the second heating power Pw_cp2', the second charging power Pc_cp2, and , PWM control of the charger 38 and the step-down DC / DC converter 20 is performed based on the second charging time t_cp2.

<Second Embodiment>
In the flow shown in FIG. 3, the estimated battery temperature Tb (t1) and the minimum reference temperature Tb (t1 *) at the time when the first charging flow (CP1) is completed are compared. Comparisons may be made.

FIG. 9 illustrates an external charging flow with temperature rise according to the second embodiment. Since the contents of the steps with the same step reference numerals as those in FIG. 3 are the same, the description thereof will be omitted as appropriate.

In this flow, instead of step S22 for determining whether the estimated battery temperature Tb (t1) is less than the minimum reference temperature Tb (t1 *), the battery estimated temperature Tb (t1) at the time when the first charging flow is completed and the maximum is T1. It is determined whether or not the sum of the temperature rise amounts ΔTmax is less than the discharge target temperature Td (S40). Similarly, instead of step S32 for determining whether the estimated battery temperature Tb (t1') is less than the minimum reference temperature Tb (t1 *), the estimated battery temperature Tb (t1') at the first charge flow completion time t1' ) And the maximum temperature rise amount ΔTmax, it is determined whether or not the sum is less than the discharge target temperature Td (S42). FIG. 10 shows an example in which Tb (t1) + ΔTmax <Td in step S40.

By providing such a criterion, the total battery temperature Tb (t2) (= Tb (t1) + ΔTmax) raised through the first charging flow and the second charging flow reaches the discharge target temperature Td. Whether or not it is clarified, and the excess or deficiency of the temperature rise can be intuitively determined.

10 Main battery, 24 Control unit, 26 Battery heater, 30 AC power supply (external power supply), 48 Battery temperature sensor, 52 CP1 power distribution calculation unit (1st power distribution unit), 54 CP1 charge efficiency map database, 56 CP2 power distribution Calculation unit (second power distribution unit), 58 CP2 charging condition database, 60 power distribution adjustment unit (adjustment unit), 62 charging power control unit.

Claims (1)

It is an in-vehicle battery charging system that can be charged externally by charging the battery mounted on the vehicle from an external power source outside the vehicle.
A heater that raises the temperature of the battery and
A control unit that manages the charge of the battery and controls the heater,
With
The control unit
At the time of the external charging, a first charging mode for charging the battery with a relatively large power and a second charging mode for charging the battery with a relatively small power after the first charging mode are executed.
In the first charging mode, the external power supplied from the external power source is combined with the first heating power supplied to the heater so that the charging time is the shortest based on the charging efficiency according to the temperature of the battery. , A first power distribution unit that allocates power to the first charging power to the battery,
In the second charging mode, the maximum heating amount in the second charging mode is obtained from the maximum heating power obtained by subtracting a predetermined second charging power from the external power and the execution period of the second charging mode. 2nd power distribution department and
When the estimated battery temperature at the time of completion of the first charging mode based on the first heating power is less than the minimum reference temperature obtained by subtracting the maximum heating amount from the discharge target temperature obtained from the discharge efficiency according to the temperature of the battery. In some cases, the additional heating power corresponding to the temperature difference between the minimum reference temperature and the estimated battery temperature is applied so that the battery temperature at the time of completion of the second charging mode can be raised to the discharge target temperature. An adjusting unit that adds to the first heating power and reduces the first charging power so that the sum of the added first heating power and the first charging power is equal to or less than the maximum power of the external power. ,
Equipped with a,
An in- vehicle battery charging system in which the discharge target temperature is a temperature higher than the charging target temperature obtained from the charging efficiency .