JP4085682B2 - Vehicle power management method, vehicle power management device, and vehicle power management program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vehicle power management method and a vehicle power management device, and more particularly, in a vehicle having a motor generator that drives an auxiliary machine when the vehicle is stopped and drives the vehicle for a predetermined period when the vehicle starts. The present invention relates to a vehicle power supply management method and a vehicle power supply apparatus used.
[0002]
[Prior art]
From the viewpoint of global warming prevention and resource saving, hybrid vehicles (hereinafter referred to as HV) are attracting attention. The HV vehicle includes a power source for a vehicle such as a secondary battery mounted on the vehicle, and travels by driving a motor using this as a power source.
[0003]
While the vehicle is stopped, the HV vehicle drives auxiliary equipment (such as an air conditioner) by operating a motor / generator functioning as a drive device using the secondary battery. Therefore, the engine is stopped while the vehicle is stopped. At the time of starting, the motor / generator drives the vehicle using the secondary battery. At this time, the engine is also restarted. Thereby, the HV vehicle can improve the fuel consumption rate.
[0004]
Therefore, in the HV vehicle, the output voltage from the secondary battery needs to be maintained at a predetermined value or more when the vehicle is stopped and at the time of starting. If the voltage output from the secondary battery is insufficient when the vehicle is stopped and at the time of starting, there is a problem that the auxiliary machinery does not function sufficiently while the vehicle is stopped, or sufficient acceleration cannot be obtained at the time of starting. .
[0005]
Secondary batteries usually deteriorate with age. That is, since the internal resistance of the secondary battery is increased by repeatedly charging and discharging, the output voltage of the secondary battery used when the vehicle is stopped or at the time of starting is decreased.
[0006]
Therefore, it is necessary to keep track of the deterioration status of the secondary battery at all times, particularly in HV vehicles.
[0007]
As a method for determining the deterioration status of the secondary battery, there is a method for obtaining the internal resistance of the secondary battery. In the method of determining the deterioration state based on the internal resistance of the secondary battery, the degree of deterioration is determined based on the obtained internal resistance value.
[0008]
As described above, when the internal resistance is obtained as a method of determining the deterioration state of the secondary battery, it is necessary to easily obtain a more accurate internal resistance in order to grasp the deterioration state more accurately. As methods for determining the deterioration status of the secondary battery by obtaining the internal resistance, there are JP-A-8-336202, JP-A-2001-20881, and JP-A-2001-228226.
[0009]
[Problems to be solved by the invention]
However, in the method for determining a battery state (battery deterioration state) disclosed in JP-A-8-336202, the discharge current and voltage of the secondary battery are measured under discharge under the same conditions. Therefore, there is a possibility that the measurement value includes an error.
[0010]
Further, in Japanese Patent Laid-Open No. 2001-208813, in order to calculate an accurate internal resistance, an open circuit voltage (hereinafter referred to as OCV) which is a no-load voltage, a discharge current and a voltage at the time of load are calculated. A method for calculating the internal resistance using the method is disclosed. However, in an HV vehicle, there are few opportunities to measure OCV, which is a voltage at no load. As a result, it is difficult to frequently determine the deterioration status of the secondary battery.
[0011]
Similarly, in Japanese Patent Laid-Open No. 2001-228226, the internal resistance is calculated from the OCV measured when there is no load and in an equilibrium state, and the discharge current and voltage measured thereafter. However, with this method, the OCV cannot be measured unless an unloaded equilibrium state is established. Therefore, as in Japanese Patent Laid-Open No. 2001-20881, there are few opportunities to measure OCV, and it is difficult to always determine the deterioration state of the secondary battery.
[0012]
An object of the present invention is to provide a vehicle power management method and a vehicle power management device that can accurately and easily determine a deterioration state of a secondary battery.
[0013]
[Means for Solving the Problems]
A vehicle power management method according to the present invention is a vehicle power management method used in a vehicle having a motor generator that drives an auxiliary machine when the vehicle is stopped and drives the vehicle for a predetermined period when the vehicle starts. Measuring the first voltage and the first discharge current of the vehicle power source at a first predetermined time while the vehicle is stopped, and at a second predetermined time after the lapse of a predetermined period from the start of the vehicle. Measuring a second voltage and a second discharge current of the power supply; calculating an internal resistance of the vehicle power supply from the first and second voltages and the first and second discharge currents; And determining a deterioration state of the power source for the vehicle based on the calculated internal resistance.
[0014]
Since the vehicle repeatedly stops and starts, the vehicle power management method according to the present invention can easily measure the first and second discharge currents and the first and second voltages. As a result, the deterioration state of the secondary battery can always be grasped. In addition, since the internal resistance is calculated by measuring different discharge currents and voltages at the time of stopping and at the time of starting, an accurate internal resistance can be calculated.
[0015]
Preferably, the step of calculating the internal resistance further includes a step of correcting the capacity of the internal resistance calculated from the first and second voltages and the first and second discharge currents; and Correcting the temperature.
[0016]
Thereby, in the vehicle power management method according to the present invention, the internal resistance can be calculated more accurately.
[0017]
A vehicle power management device according to the present invention is a vehicle power management device used in a vehicle having a motor generator that drives an auxiliary machine when the vehicle is stopped and drives the vehicle for a predetermined period when the vehicle starts. It includes measurement means, calculation means, and determination means. The measuring means measures the voltage and discharge current of the vehicle power supply, and more specifically, at a first predetermined time when the vehicle is stopped and a second predetermined time after a predetermined period has elapsed since the vehicle started. Measure the voltage and discharge current of the vehicle power supply. The calculating means calculates the internal resistance of the vehicle power supply based on the voltage and discharge current measured by the measuring means. The determination means determines a deterioration state of the vehicle power supply based on the calculated internal resistance.
[0018]
Since the vehicle repeatedly stops and starts, the vehicle power management method according to the present invention can easily measure the first and second discharge currents and the first and second voltages. As a result, the deterioration state of the secondary battery can always be grasped. In addition, since the internal resistance is calculated by measuring different discharge currents and voltages at the time of stopping and at the time of starting, an accurate internal resistance can be calculated.
[0019]
Preferably, the calculating means further calculates the internal resistance after correcting the temperature and correcting the capacity of the internal resistance calculated based on the voltage and the discharge current measured by the measuring means.
[0020]
Thereby, in the vehicle power management method according to the present invention, the internal resistance can be calculated more accurately.
[0021]
The vehicle power supply management program according to the present invention is a vehicle power supply that is executed by a computer used in a vehicle having a motor generator that drives an auxiliary machine when the vehicle is stopped and drives the vehicle for a predetermined period when the vehicle starts. A management program for measuring a first voltage and a first discharge current of a vehicle power supply at a first predetermined time when the vehicle is stopped; and a second after a predetermined period has elapsed since the vehicle started. At a predetermined time, from the step of measuring the second voltage and the second discharge current of the vehicle power supply, the first and second voltages, and the first and second discharge currents, the inside of the vehicle power supply A step of calculating a resistance, and a step of determining a deterioration state of the power source for the vehicle based on the calculated internal resistance.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.
[0023]
FIG. 1 is a block diagram showing the configuration of a vehicle power management device according to an embodiment of the present invention.
[0024]
The vehicle power management device 10 includes an inverter 1, a motor / generator 2, an ECU (Electrical Control Unit) 3, an ammeter 4, a vehicle power supply 5, a voltage sensor 6, and a temperature sensor 7.
[0025]
The motor / generator 2 is a three-phase AC induction motor or a synchronous motor. The driving force of the motor / generator 2 is transmitted to the wheels when starting. Further, the motor / generator 2 is used as a generator during normal running or deceleration. The voltage generated by the power generation action of the motor / generator is supplied to the vehicle power source 5 via the inverter 1. The motor / generator 2 is grounded to the vehicle body 8.
[0026]
When the motor / generator 2 functions as a motor, the inverter 1 converts a DC voltage output from the vehicle power supply 5 into an AC voltage. When the motor / generator 2 functions as a generator, the AC voltage generated by the motor / generator 2 is converted into a DC voltage, and the vehicle power supply 5 is charged.
[0027]
The vehicle power source 5 is a secondary battery capable of charging and discharging, such as a lead storage battery, a nickel cadmium battery, a nickel / hydrogen battery, and a lithium secondary battery. The vehicle power supply 5 is grounded to the vehicle body 8.
[0028]
The ammeter 4 measures the discharge current of the vehicle power supply 5 in accordance with a command from the ECU 3 and transmits the result to the ECU 3.
[0029]
The voltage sensor 6 measures the voltage of the vehicle power supply 5 in accordance with a command from the ECU 3 and transmits the result to the ECU 3.
[0030]
The temperature sensor 7 measures the temperature of the vehicle power supply 5 in accordance with a command from the ECU 3 and transmits the result to the ECU 3.
[0031]
The ECU 3 is a microcomputer including a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), an input / output device (none of which is shown). The ECU 3 stores a vehicle power management program in advance.
[0032]
The ECU 3 includes a measuring unit 31, a calculating unit 32, and a determining unit 33, and is grounded to the vehicle body 8. The measuring unit 31 instructs the ammeter 4, the voltage sensor 6, and the temperature sensor 7 to measure the discharge current, voltage, and temperature, respectively, at a predetermined time, and acquires the measurement results. In addition, the calculation unit 32 calculates the internal resistance of the vehicle power supply 5 using the discharge current and voltage acquired by the measurement unit 31. Further, the calculation unit 32 performs temperature correction and capacity correction on the calculated internal resistance. The determination unit 33 determines the deterioration status of the vehicle power supply 5 based on the internal resistance determined by the calculation unit 32.
[0033]
The operation of the vehicle power management device 10 having the above configuration will be described.
FIG. 2 is a flowchart showing the operation of the vehicle power management device 10 shown in FIG. FIG. 3 is a graph showing the voltage and discharge current of the vehicle power supply when the HV vehicle is stopped (during auxiliary driving), at startup, and at engine rotation. The term "stopped" refers to a state in which the HV vehicle is stopped by a red signal or the like. At this time, the engine is stopped and an auxiliary device such as an air conditioner is driven by the motor / generator 2. It is a period. In addition, the time of starting is a period in which the motor / generator 2 drives the vehicle and the engine is rotated again at the stage of driving the stopped vehicle. The time when the engine is rotating is a period during which the vehicle is driven only by driving by the engine. At this time, the vehicle power source 5 is charged to a predetermined amount by the power generation function of the motor / generator 2.
[0034]
Referring to FIGS. 2 and 3, at time t1 when the vehicle is stopped, that is, when an auxiliary device such as an air conditioner is being driven, measurement unit 31 in ECU 3 measures the discharge current of vehicle power supply 5 by ammeter 4. To receive the measurement result I1. In addition, the measurement unit 31 instructs the voltage sensor 6 to measure the voltage of the vehicle power supply, and receives the measurement result V1. Similarly, the measurement unit 31 instructs the temperature sensor 7 to measure the temperature of the vehicle power supply 5 and receives the measurement result T1 (step S1).
[0035]
When the HV vehicle starts at time t2, the motor / generator 2 drives the vehicle. At this time, since the motor / generator 2 is in an accelerated state for a predetermined period from time t2, the discharge current and voltage are not stable. However, immediately before time t3 when the engine has rotated a predetermined number of times from time t2, the motor / generator 2 shifts from the acceleration state to the steady state. As a result, at time t3, the discharge current and voltage of the vehicle power supply are stabilized. Time t3 is determined by the engine speed.
[0036]
At the time t3 when the discharge current and voltage of the vehicle power supply 5 are stabilized at the start, the measuring unit 31 in the ECU 3 instructs the ammeter 4 and the voltage sensor 6 to measure the discharge current and voltage again. As a result, the measurement unit 31 acquires the discharge current I2 and the voltage V2 of the vehicle power source 5 by the ammeter 4 and the voltage sensor 6 (step S2).
[0037]
Subsequently, the calculation unit 32 in the ECU 3 calculates the internal resistance R of the vehicle power source using the measured discharge currents I1 and I2 and the voltages V1 and V2 (step 3). The internal resistance R1 is calculated by the following formula.
[0038]
R1 = (V1-V2) / (I1-I2)
With the above calculation method, the calculation unit 32 can calculate the internal resistance regardless of the OCV. Further, since the discharge current and voltage at the time of stopping and starting of the vehicle are obtained, the internal resistance can be calculated frequently and easily.
[0039]
Furthermore, the calculation unit 32 performs capacity correction and temperature correction for the internal resistance R1 obtained in step S3 (step S4). The capacity means a state of charge (hereinafter referred to as SOC).
[0040]
FIG. 4 is a diagram showing the relationship between the internal resistance, SOC, and temperature of the vehicle power supply.
In the graph of FIG. 4, the vertical axis indicates internal resistance, and the horizontal axis indicates temperature. C0 is the relationship between the temperature and the internal resistance at SOC = S0 of the vehicle power supply at the time of shipment. C1 is the relationship between the temperature and the internal resistance at SOC = S1 of the vehicle power supply in use. Similarly, C2 is a relational expression between the temperature and the internal resistance at the SOC = S0 of the vehicle power source in use. The calculating unit 32 stores an empirically obtained relational expression f (S, T) between the internal resistance, the SOC, and the temperature.
[0041]
Here, a method of correcting the internal resistance R1 by the calculation unit 32 will be described.
First, it is assumed that the temperature, SOC, and internal resistance of the vehicle power source 5 acquired in step S1 are T1, S1, and R1, respectively.
[0042]
Here, when the internal resistance R1 at SOC = S1 is converted into the internal resistance at the time of the reference SOC = S0, R2 is obtained from the relational expression f (S, T) of the internal resistance, SOC, and temperature obtained empirically. .
[0043]
Further, R2 is converted into an internal resistance R0 at the reference temperature T0. The internal resistance R0 can be obtained by the following expression, where f (S, T) is a relational expression between the internal resistance, the SOC, and the temperature obtained empirically as described above.
[0044]
R0 = R1 × f (S1, T1)
By the above method, the correction resistor R0 corrected to the resistance at the predetermined SOC and the predetermined temperature can be calculated from the resistor R1.
[0045]
Subsequently, the determination unit 33 determines the deterioration state of the vehicle power supply 5 (step S5). The determination is made by the following method.
[0046]
When determining the deterioration status of the vehicle power supply 5 by the correction resistor R0, the determination unit 33 determines whether or not the correction resistor R0 exceeds the predetermined reference resistance Rx shown in FIG. When the correction resistor R0 is smaller than the reference resistor Rx, the determination unit 33 determines that the vehicle power source 5 can be used. When the correction resistor R0 is larger than the reference resistor Rx, the determination unit 33 determines that the vehicle power source 5 has deteriorated. A plurality of determination criteria can also be set. When a plurality of determination criteria are set, optimal control of the vehicle power supply according to the deterioration level can be performed.
[0047]
On the other hand, the determination can be made by other methods.
Let R be the internal resistance when the temperature T of the vehicle power supply is in use (SOC = S0). Further, the internal resistance at the temperature T of the vehicle power supply at the time of shipment (SOC = S0) is Rs. Here, the determination value G is defined as follows.
[0048]
G = R / Rs
The determination unit 33 can also determine whether or not the determination value G exceeds a predetermined reference value.
[0049]
Referring to FIG. 4, the internal resistance at the time of use of SOC = S0 and temperature of vehicle power supply 5 = T1 is from C2 to internal resistance R2. Further, the internal resistance at the time of shipment of SOC = S0 and the temperature of the vehicle power supply = T1 is C0 to R3. Therefore, the determination value G is obtained by the following formula.
[0050]
G = R2 / R3
The determination unit 33 determines whether or not the determination value G exceeds a predetermined reference value.
When the determination value G is smaller than the reference value, the determination unit 33 determines that the vehicle power source 5 is usable. When the determination value G is larger than the reference value, the determination unit 33 determines that the vehicle power source 5 has deteriorated.
[0051]
The embodiments disclosed herein are illustrative in all respects and should not be construed as being restrictive. The scope of the present invention is defined by the scope of the claims, not the embodiment described above, and is intended to include meanings equivalent to the scope of the claims and all modifications within the scope.
[0052]
【The invention's effect】
Since the vehicle repeatedly stops and starts, the first and second discharge currents and the first and second voltages can be easily measured by the vehicle power management method and the vehicle power management device according to the present invention. As a result, the deterioration state of the secondary battery can be grasped easily and frequently. Furthermore, since the discharge current and voltage which are different at the time of stopping and at the time of starting are measured and the internal resistance is calculated, it is not necessary to measure the OCV, and an accurate internal resistance can be calculated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a vehicle power management device according to an embodiment of the present invention.
FIG. 2 is a flowchart showing the operation of the vehicle power management device 10 shown in FIG.
FIG. 3 is a graph showing a voltage and a discharge current of a vehicle power source when the HV vehicle is stopped (when an auxiliary machine is being driven), during start-up, and when the engine is rotating.
FIG. 4 is a diagram showing a relationship among internal resistance, SOC, and temperature of a vehicle power source.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inverter, 2 Motor generator, 3 ECU, 4 Ammeter, 5 Power supply for vehicles, 6 Voltage sensor, 7 Temperature sensor, 8 Vehicle body, 10 Power management device for vehicles, 31 Measurement part, 32 Calculation part, 33 Determination part.

Claims (5)

A vehicle power management method used in a vehicle having a motor generator that drives an auxiliary machine when the vehicle is stopped and drives the vehicle for a predetermined period when the vehicle starts,
Measuring a first voltage and a first discharge current of the power source for the vehicle at a first predetermined time when the vehicle is stopped;
Measuring a second voltage and a second discharge current of the vehicle power supply at a second predetermined time after a predetermined period has elapsed since the vehicle started;
Calculating an internal resistance of the vehicle power source from the first and second voltages and the first and second discharge currents;
Determining a deterioration state of the vehicle power source based on the calculated internal resistance. The step of calculating the internal resistance further includes
Capacity correcting the internal resistance calculated from the first and second voltages and the first and second discharge currents;
The vehicle power management method according to claim 1, further comprising a step of performing temperature correction on the capacity-corrected internal resistance. A vehicle power management device used in a vehicle having a motor generator that drives an auxiliary machine when the vehicle is stopped and drives the vehicle for a predetermined period when the vehicle starts,
Measuring means for measuring the voltage and discharge current of the vehicle power supply;
Calculating means for calculating an internal resistance of the vehicle power supply based on the voltage and discharge current measured by the measuring means;
Determination means for determining a deterioration state of the vehicle power supply based on the calculated internal resistance,
The measuring means measures a voltage and a discharge current of the vehicle power source at a first predetermined time when the vehicle is stopped and a second predetermined time after a predetermined period has elapsed since the start of the vehicle. Power management device. The calculating means further includes
The vehicle power management device according to claim 3, wherein the internal resistance calculated based on the voltage and the discharge current measured by the measuring unit is subjected to capacity correction, and the temperature-corrected internal resistance is calculated. A vehicle power management program for causing a computer to execute the steps according to claim 1 or 2.

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