Patent ID: 12218531

DETAILED DESCRIPTION OF THE INVENTION

In the following, an embodiment of a charge control device1according to the present invention will be described. The charge control device1controls charging of the battery3installed in a vehicle2such as an electric car or a plug-in hybrid vehicle.

As shown inFIG.1, a battery system4includes a battery3, a connection port6, a battery charger7, and an operation terminal8, in addition to the charge control device1. The battery3includes multiple cells such as lithium ion battery cells. The multiple cells are connected in series or in parallel with each other. The battery3supplies electric power to an electric motor11, which is a drive source of the vehicle2, and to various auxiliary devices12. Also, the battery3is charged by receiving regenerative electric power from the electric motor11and electric power from an external power supply16.

The battery3is provided with a cooling device13. The cooling device13has a coolant circulation flow path through which a coolant (for example, water) is circulated, a cooler (such as a radiator) that cools the coolant, and a coolant pump that circulates the coolant. The circulation flow path is arranged such that the coolant flowing therethrough can exchange heat with the battery3. The battery3is cooled by exchanging heat with the coolant.

The auxiliary devices12are driven by the electric power supplied from the battery3. The auxiliary devices12include, for example, an air conditioner, a pump that circulates the coolant of the electric motor11, a pump that circulates the coolant of the cooling device13, a heater for heating the battery3, etc.

The connection port6is provided in the vehicle2and can be connected with the external power supply16via a charging cable15. The external power supply16is an AC power supply. The battery charger7is a so-called onboard charger installed in the vehicle2. The battery charger7is an electric circuit that converts the electric power supplied from the AC power supply to electric power suitable for charging of the battery3and supplies the converted electric power to the battery3. The battery charger7includes an AC/DC converter, a DC/DC converter, a controller, and so on. The battery charger7is connected to the connection port6and the battery3.

The charge control device1includes a battery temperature acquisition unit21, a battery voltage acquisition unit22, a battery electric current acquisition unit23, an external power supply voltage acquisition unit24, an external power supply electric current acquisition unit25, a conversion efficiency acquisition unit26, a power consumption acquisition unit27, a coolant temperature acquisition unit28, an outside temperature acquisition unit29, an SOC acquisition unit31, a battery capacity acquisition unit32, and a charge time estimation unit33. The charge control device1is preferably configured by an electronic control unit (ECU) and multiple sensors connected to the ECU, where the ECU typically includes a CPU, a non-volatile memory (ROM), a volatile memory (RAM), and so on.

The battery temperature acquisition unit21is a sensor provided in the battery3to acquire the temperature of the battery3. The battery voltage acquisition unit22is a sensor provided in the battery3to acquire the voltage of the battery3. The battery voltage acquisition unit22acquires the voltage of each of the multiple cells included in the battery3(the voltage of each cell will be referred to as a cell voltage) and a total voltage of the battery3, which is the voltage of the whole unit configured by the multiple cells (hereinafter, the total voltage will be referred to as a battery voltage). The battery electric current acquisition unit23is a sensor provided in the battery3to acquire the electric current of the battery3. The battery temperature acquisition unit21, the battery voltage acquisition unit22, and the battery electric current acquisition unit23constitute a battery information acquisition unit. The battery temperature, the battery voltage, and the battery electric current may be referred to as battery information.

The external power supply voltage acquisition unit24is provided in the battery charger7to acquire the voltage of the external power supply16. The external power supply electric current acquisition unit25is provided in the battery charger7to acquire the electric current of the external power supply16. Preferably, the external power supply electric current acquisition unit25acquires the maximum electric current of the external power supply16. The conversion efficiency acquisition unit26acquires the conversion efficiency of the battery charger7. The conversion efficiency is a ratio of the electric power supplied from the battery charger7to the battery3to the electric power input from the external power supply16to the battery charger7. For example, the conversion efficiency acquisition unit26may set a predetermined value as the conversion efficiency or may set the conversion efficiency by referring to a map based on at least one of the voltage and electric current of the external power supply16. The external power supply electric current acquisition unit25, the external power supply voltage acquisition unit24, and the conversion efficiency acquisition unit26constitute an external power supply information acquisition unit. The external power supply electric current, the external power supply voltage, and the conversion efficiency may be referred to as external power supply information.

The power consumption acquisition unit27acquires an amount of electric power supplied from the battery3to the auxiliary devices12as a power consumption amount. Preferably, the power consumption acquisition unit27includes an electric current sensor that detects an electric current flowing in an electric cable connecting between the battery3and each auxiliary device12as a consumption electric current.

The coolant temperature acquisition unit28is a temperature sensor provided in the coolant circulation flow path of the cooling device13to detect the temperature of the coolant flowing in the coolant circulation passage. The outside temperature acquisition unit29is a temperature sensor that is provided on the vehicle2to acquire the outside temperature.

The SOC acquisition unit31acquires a state of charge (SOC) (charge rate [%]). The SOC acquisition unit31may acquire the SOC by using any known method. For example, the SOC acquisition unit31uses a map defining a relationship between the voltage and the SOC of the battery3to acquire the SOC based on the voltage of the battery3. Preferably, the map is updated depending on a deterioration degree of the battery3. The deterioration degree of the battery3may be preferably acquired based on the internal resistance of the battery3, for example. In another method, the SOC acquisition unit31may acquire the SOC by integrating the electric current of the battery3.

The battery capacity acquisition unit32acquires a battery capacity, namely, a full charge capacity of the battery3. The battery capacity acquisition unit32may acquire the battery capacity by using any known method. For example, the battery capacity acquisition unit32may acquire the battery capacity by multiplying the initial value of the battery capacity set beforehand by the deterioration degree.

The charge time estimation unit33estimates a charge time of the battery3(a time duration required for charging the battery3). The charge time may be converted to a charge completion time (a time point at which the charge will be completed) based on the current time. The charge time estimation unit33acquires the charge time by executing a later-described charge time estimation process.

The charge control device1is connected with the operation terminal8in a communicable manner. The operation terminal8has an interface that allows input and output. The interface preferably is a touch panel display, for example. The operation terminal8may be installed in the vehicle2and be connected with the charge control device1via a cable. Also, the operation terminal8may be a mobile terminal such as a smartphone which wirelessly communicates with the charge control device1. Also, the operation terminal8may wirelessly communicate with the charge control device1via a server41.

The operation terminal8acquires a charge completion SOC (charge completion value) according to an input operation of the user. Also, the operation terminal8outputs a charge start command to the charge control device1according to an input operation of the user. When the battery charger7is connected to the external power supply16via a cable and the charge start command is received from the operation terminal8, the charge control device1starts charging of the battery3.

The charge control device1outputs information on the charge time or the charge completion time that was estimated to the operation terminal8, and the operation terminal8displays the charge time or the charge completion time on the interface.

The charge time estimation unit33executes the charge time estimation process according to the flowchart shown inFIG.2. The charge time estimation unit33executes the charge time estimation process at the start of charging. Also, the charge time estimation unit33may execute the charge time estimation process at a predetermined time interval during charging of the battery3to update the charge time.

The charge time estimation unit33first sets 0 to time point t to initialize the time parameter (S1).

Next, the charge time estimation unit33acquire various information when time point t=0 (S2). The charge time estimation unit33acquires values when time point t=0 (namely, initial values) of the battery temperature, the coolant temperature, the outside temperature, the SOC, the maximum electric current of the external power supply16, the battery capacity of the battery3, the conversion efficiency, and the charge completion SOC. As described above, the battery temperature is acquired by the battery temperature acquisition unit21. The coolant temperature is acquired by the coolant temperature acquisition unit28. The outside temperature is acquired by the outside temperature acquisition unit29. The SOC is acquired by the SOC acquisition unit31. The maximum electric current of the external power supply16is acquired by the external power supply electric current acquisition unit25. The battery capacity of the battery3is acquired by the battery capacity acquisition unit32. The conversion efficiency is acquired by the conversion efficiency acquisition unit26. The charge completion SOC is acquired by the operation terminal8.

Next, the charge time estimation unit33adds +1 to time point t to advance time point t (S3). The increase of time point t by 1 corresponds to elapsing of a predetermined sampling time. The sampling time may be preferably set to 1 [s], for example. In the following description, a value at time point t will be referred to as a current value and a value at time point t−1, which is prior to time point t by one sampling time, will be referred to as a previous value.

Next, the charge time estimation unit33estimates the battery temperature at time point t, namely, the current value of the battery temperature (S4). The charge time estimation unit33estimates the battery temperature at time point t according to a battery temperature estimation process shown inFIG.3. For example, the charge time estimation unit33estimates the battery temperature at time point t based on a battery temperature prediction model set beforehand. In the present embodiment, the battery temperature at each time point may be estimated by inputting the initial value of the battery temperature, the initial value of the coolant temperature, and the initial value of the outside temperature into the battery temperature prediction model.

As shown inFIG.2, the charge time estimation unit33subsequently estimates the battery voltage at time point t, namely, the current value of the battery voltage (S5). As shown inFIG.4, the charge time estimation unit33estimates the battery voltage as a part of a battery electric current estimation process for estimating the battery electric current at time point t. The charge time estimation unit33calculates input electric power, which is the electric power input to the battery3, by multiplying the previous value of the battery electric current by the previous value of the battery voltage, and estimates the current value of the battery voltage by inputting the calculated input electric power and the current value of the battery temperature into a battery plant model created beforehand. In the creation of the battery plant model, the battery capacity, an SOC-OCV curve identified beforehand, the battery's internal resistance, etc. may be used in addition to the current value of the electric power of the battery and the previous value of the voltage of the battery.

As shown inFIG.2, the charge time estimation unit33then acquires a rate-determining charge electric current at time point t, namely, the current value of the rate-determining charge electric current (S6). As shown inFIG.4, the charge time estimation unit33estimates the rate-determining charge electric current as a part of the battery electric current estimation process. The charge time estimation unit33acquires electric power of the external power supply16as a product of the initial value of the maximum electric current of the external power supply16, the initial value of the voltage of the external power supply16, and the initial value of the conversion efficiency. Then, the charge time estimation unit33acquires the rate-determining charge electric current by dividing the electric power of the external power supply16by the current value of the battery voltage.

As shown inFIG.2, the charge time estimation unit33then acquires the value of the consumption electric current of the all auxiliary devices12at time point t (S7).

Next, the charge time estimation unit33acquires a supply electric current at time point t, namely, the current value of the supply electric current (S8). The supply electric current is the electric current supplied from the external power supply16to the battery3. As shown inFIG.4, the charge time estimation unit33estimates the supply electric current as a part of the battery electric current estimation process. The charge time estimation unit33refers to an electric current map set beforehand based on a predetermined maximum value of the cell voltage and the current value of the battery temperature to acquire a current value of an electric current limit value. The electric current map defines a relationship between the maximum value of the cell voltage, the battery temperature, and the electric current limit value. The electric current limit value is an electric current value set to protect the battery3when charged. Protection of the battery3includes suppressing deterioration due to a rise of the temperature of the battery or the like, electrodeposition in the battery, or any other deterioration factors. The charge time estimation unit33compares the current value of the rate-determining charge electric current, the initial value of the maximum electric current of the external power supply16, and the current value of the limit electric current, and sets the minimum of them as the current value of the supply electric current.

As shown inFIG.2, the charge time estimation unit33then acquires the battery electric current at time point t, namely, the current value of the battery electric current (S9). As shown inFIG.4, the charge time estimation unit33acquires the battery electric current as a part of the battery electric current estimation process. The charge time estimation unit33acquires the current value of the battery electric current by subtracting the consumption electric current value from the current value of the supply electric current.

As shown inFIG.2, the charge time estimation unit33then acquires the SOC at time point t, namely, the current value of the SOC (S10). As shown inFIG.5, the charge time estimation unit33acquires the current value of the SOC as a part of a charging stop determination process. The charge time estimation unit33multiplies the current value of the battery electric current by the sampling time, thereby to acquire an amount of electric charge supplied to the battery3in the sampling time. The amount of electric charge supplied to the battery3in the sampling time corresponds to an integrated value obtained by integrating the current value of the battery electric current with the sampling time. Then, the charge time estimation unit33divides the amount of electric charge supplied to the battery3in the sampling time by the battery capacity to acquire the current value of an amount of change of the SOC in the sampling time. Then, the charge time estimation unit33adds the current value of the amount of change of the SOC in the sampling time to an accumulated SOC change amount, which is the total of the amount of change of the SOC in each sampling time up to the previous calculation, thereby to acquire the amount of change of the SOC from the start of charge to time point t, namely, the current value of the accumulated SOC change amount. Then, the charge time estimation unit33adds the amount of change of the SOC from the start of charge to time point t (the accumulated SOC change amount) to the initial value of the SOC to acquire the current value of the SOC. In another embodiment, the charge time estimation unit33may acquire the current value of the SOC by adding the current value of the amount of change of the SOC in the sampling time to the previous value of the SOC.

As shown inFIG.2, the charge time estimation unit33then determines whether a charging stop condition is satisfied (S11). As shown inFIG.5, the charge time estimation unit33determines that the charging stop condition is met when the current value of the SOC is greater than or equal to the charge completion SOC.

When the current value of the SOC is less than the charge completion SOC and hence the charging stop condition is not satisfied (determination result of S11is No), the charge time estimation unit33repeats the process from step S3to step S11. When the charging stop condition is satisfied (determination result of S11is Yes), the charge time estimation unit33converts time point t to time based on the sampling time, thereby to acquire the charge time (S12).

According to the charge control device1and the charge control method of the above-described embodiment, since the charge time is estimated by taking into account the battery temperature and the electric power consumption, the charge time can be estimated accurately. Because the charge control device1acquires the state of charge at each time point by taking into account the battery temperature at each time point, the charge time can be estimated accurately. Also, for example even if the amount of electric power (electric current) supplied from the external power supply changes during charging, the charge time can be estimated accurately by taking into account such a change. Note that in another embodiment, it is possible to acquire an elapsed time from the start of charge or the cell voltage or electric current of the battery as a charging completion condition alternative to the charge completion SOC, and to perform determination on the charging completion based thereon.

Concrete embodiments of the present invention have been described in the foregoing, but the present invention is not limited to the above embodiments and may be modified or altered in various ways.