JP3395670B2 - Hybrid vehicle - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hybrid vehicle, and more particularly to a hybrid vehicle which can be controlled in an ideal state even when a lithium ion battery is deteriorated.

[0002]

2. Description of the Related Art Generally, a parallel type hybrid vehicle is equipped with an engine and a motor for generating a driving torque and transmitting the driving torque to a driving shaft. It is a vehicle with high efficiency. In such a hybrid vehicle, a lithium ion battery having a high energy density is used as a battery.

Further, when the hybrid vehicle decelerates, the motor is controlled to a regenerative state so that the battery is charged with the regenerated electric power according to the rotation transmitted from the drive shaft to the motor.

More specifically, in a control device used in a hybrid vehicle, the state of charge SOC (State of C) of the battery is
The amount of power generation, the amount of drive, and the amount of regeneration were controlled according to the harge).

For example, as shown in FIG. 7, when the maximum charging power of the vehicle is 16 (kW) and the maximum discharge output is 25 (kW), the input / output power can be changed with respect to the discharging performance and charging performance of a new battery. The state of charge SOC that can be used is within the range of 16-25 (kW), the usable range is 18-82%
It was. Therefore, the predetermined target SOC representing the usable state of charge state of the lithium ion battery when it is new is set to 5
It was set to the 0% position and used for control.

[0006]

However, when the lithium ion battery deteriorates due to aging, the discharge capacity decreases and the internal resistance tends to increase.

As a result, as shown in FIG. 7, the SOC usable range of the input / output power is 16 to 25 (kW) with respect to the discharge performance and charge performance of the deteriorated battery. It can be seen that the value is up to 65%, which is extremely narrow.

Therefore, the target SOC set when the product is new
When the prescribed control is performed using the battery after deterioration, there was a problem that the lithium-ion battery could not be controlled in an ideal state because it could not exhibit sufficient charge / discharge performance like a new product. .

The present invention has been made in view of the above,
It is therefore an object of the present invention to provide a hybrid vehicle that can maximize fuel efficiency even when the battery deteriorates.

[0010]

The invention according to claim 1 is
In order to solve the above problems, an engine that generates a running torque, a battery, a motor that receives a power supply from the battery to generate a running torque, a charge state detection unit that detects a charge state of the battery, and a detected battery Target charging state
In a parallel type hybrid vehicle having a control means for distributing a power source for generating a running torque in comparison with a value , a deterioration state determination means for determining a deterioration state of a battery, and the target charging based on the deterioration state of the battery Correction means for correcting the state value, the deterioration state determination means,
Based on the current and voltage of the battery, the maximum output
Maximum output power calculating means for calculating a large output power, and
Maximum output power delivered and when fully charged when new
Maximum output power by comparing with the reference value of maximum output power of
Output reduction rate calculation that calculates the output reduction rate that represents the deterioration state of
And the deterioration state of the current capacity according to the output reduction rate.
A capacity reduction rate calculation means for calculating the capacity reduction rate
However, the correction means is responsive to the calculated capacity decrease rate.
First correction value calculation for calculating the first correction value of the target state of charge value by
Output means, the calculated maximum output power, output reduction
The maximum output power based on the rate and capacity reduction rate
The maximum output possible charge state value that represents the charge state that can
Maximum output possible charge state value calculating means for calculating the maximum
The predetermined value is the value obtained by subtracting the first modified value from the output charge state value
If it is smaller than the
The value obtained by subtracting the predetermined value of
The value obtained by subtracting the first correction value from the available charging state value is the predetermined value
If it is larger than the above, the first correction value is set to the target state of charge value.
And a second correction value calculating means .

In order to solve the above-mentioned problems, the present invention provides an engine, a power generation mechanism driven by the engine, a battery charged by the power generation mechanism, and a running torque when supplied with electric power from the battery. A serial hybrid vehicle having a motor that is generated, a charge state detection unit that detects the charge state of the battery, and a control unit that compares the detected charge state of the battery with a target charge state value and controls the operation of the power generation mechanism. In the above, the deterioration state determination means for determining the deterioration state of the battery, and the target charging state based on the deterioration state of the battery
And a correction means for correcting the status value, the deterioration state determination hand
The stage outputs the battery based on the current and voltage of the battery.
Maximum output power calculator to calculate the maximum possible output power
Tier, calculated maximum output power, and fully charged when new
Output is compared with the reference value of maximum output power
Output low that calculates the output decrease rate that indicates the deterioration state of force power
The ratio calculation means and the current capacity
Capacity reduction rate calculating means for calculating the capacity reduction rate representing the activated state
And the correcting means reduces the calculated capacity decrease.
First calculating a first correction value of the target state of charge value according to the rate
Correction value calculation means, the calculated maximum output power, output
The maximum output power is subtracted based on the power reduction rate and capacity reduction rate.
Maximum outputable charge status indicating the charge status that can be output
Maximum output possible charge state value calculating means for calculating the state value,
The value obtained by subtracting the first correction value from the maximum output possible charge state value is
If it is smaller than the specified value, the maximum output possible state of charge value
The value obtained by subtracting this predetermined value from
The value obtained by subtracting the first modified value from the maximum outputable charge state value is
When it is larger than the fixed value, the first correction value is set to the target charge.
And a second correction value calculating means for setting the state value .

[0012]

[0013]

[0014]

According to the invention described in claim 1, the power for correcting the target state of charge based on the deterioration state of the battery and comparing the state of charge of the battery with the target state of charge value to generate the running torque. Since the power is distributed, maximum fuel efficiency can be obtained even when the battery deteriorates. Furthermore, from the maximum output possible charge state value to the target charge state
If the value obtained by subtracting the value is smaller than the specified value, maximum output
The value obtained by subtracting this predetermined value from the available charge status value is the target charge status.
By correcting it as a state value, the deterioration state of the battery is further increased.
The target charge status value can be corrected even if
Wear.

According to the second aspect of the invention, the target state of charge value is corrected based on the deterioration state of the battery, and the state of charge of the battery is compared with the target state of charge value to control the operation of the power generation mechanism. Therefore, even if the battery deteriorates, the maximum fuel efficiency can be obtained. Furthermore
, Subtract the target charge state value from the maximum output possible charge state value
If the value is less than the specified value, maximum output possible charging
The target charge state value is the value obtained by subtracting this predetermined value from the state value.
By correcting the
The target state-of-charge value can be corrected even if

[0016]

[0017]

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a system configuration of a parallel type hybrid vehicle 1 according to an embodiment of the present invention.

The hybrid vehicle 1 has an engine 3 and a motor A5 for generating a driving torque and transmitting it to a driving shaft.
The vehicle is provided with the following, and the control of the engine 3 and the motor A5 is switched according to the traveling state to improve the efficiency of fuel efficiency.

The engine 3 is an internal combustion engine that generates a driving torque, and the driving torque is controlled by a torque command from the HVCU 23 described later.

The motor A5 is a three-phase AC motor that generates a driving torque and transmits it to the drive shaft, and the driving torque is controlled by a three-phase AC from an inverter A9 described later.

The motor B7 is a three-phase AC motor that starts the engine 3 and generates electric power according to the rotation of the engine to supply electric power to the battery. The motor B7 controls the drive torque by the three-phase AC from the inverter B11 described later. To be done.
The motor B7 generates electric power by rotating the engine 3, while the motor A5 generates electric power by regeneration during deceleration.

The inverter A9 has a plurality of switching elements inside, and controls the switching elements to be turned on / off according to a PWM signal from an HVCU 23 described later, thereby converting the DC power from the battery 13 into AC power. . The inverter B11 has a plurality of switching elements inside, and performs on / off control of these switching elements according to a PWM signal from the HVCU 23 described later, thereby converting DC power into AC power. The inverters A9 and B11 are connected to the motor A connected to each.
5, B7 converts AC power into DC power at the time of regeneration and charges the battery 13.

The battery 13 is equipped with a lithium ion battery as a secondary battery having a high output density. The voltage sensor 15 detects the DC voltage V across the battery 13. The current sensor 17 includes a battery 13 and an inverter A.
The direct current I flowing between B9 and B9 is detected. The temperature sensor 19 is added to the battery 13,
The temperature T of is detected.

BCU (battery control unit)
Reference numeral 21 will be described later based on the DC current I of the battery 13 detected by the current sensor 17, the temperature T of the battery 13 detected by the temperature sensor 19, and the DC voltage V across the battery 13 detected by the voltage sensor 15. HVCU23 by calculating target SOC, regeneration and output limit value, current SOC, etc.
Is set every predetermined time.

The HVCU 23 (hybrid vehicle control unit) is a target SOC from the BCU 21,
Regeneration / output limit value, current SOC, accelerator pedal 3
PW indicating the drive assist amount by the motor A5 based on the accelerator opening from 1 and the vehicle speed value from the vehicle speed sensor 33.
An M signal (or a PWM signal that controls the regenerative power generation amount during deceleration) is generated and output to the inverter A9, and a target torque value that represents the drive torque to be output to the engine 3 is also generated and output to the engine 3. The amount of power generated by the motor B7 is controlled. The HVCU 23 detects the state of charge of the battery, suppresses the power consumption of the battery when the state of charge of the battery falls below a target value, and runs with the driving force of the engine, and when the state of charge of the battery rises above the target value, consumes the power of the battery It is controlled to remove the restriction.

The HVCU 23 and BCU 21 each have a CPU, a ROM, a RAM, a timer, etc., and are controlled according to a control program stored in each ROM. Further, the engine 3 is equipped with an engine control unit (not shown), and
It is assumed that air-fuel ratio control is being performed on the engine based on the target torque value received from U23.

Next, the operation of the HVCU 23 and BCU 21 will be described with reference to the flow charts shown in FIGS.
The control program represented by this flowchart is a ROM provided inside the HVCU 23 and BCU 21.
Is stored in each controller, and each controller executes a process every predetermined time.

First, in the HVCU 23, step S
In 10, internal R for HVCU23 and BCU21
Start processing including initialization of AM and the like is performed. According to this start-up process, internal RAM of HVCU23 and BCU21
Will be initialized and each controller will be activated thereafter.

Then, in step S20, the accelerator pedal opening 31 is input to the HVCU 23, and the current vehicle speed value is input from the vehicle speed sensor 33.
Then, in step S30, the driving force torque required to drive the vehicle is calculated based on the input accelerator opening and vehicle speed value, vehicle specifications such as vehicle weight and gear ratio.

Then, in step S40, the BCU 21
Input the battery regeneration and output limit value described later from.

Then, in step S50, the BCU 21
Then, the current SOC and the target SOC, which will be described later, are input, and the power generation requirement to be required for the motors A5 and B7 is calculated. The power generation demand can be expressed as a function of the value obtained by subtracting the target SOC from the current SOC.

Then, in step S60, the amount of electric power generated by the motor B is determined with respect to the calculated power generation demand.

Then, in step S70, the amount of drive (regeneration) electric power by the motor A is determined. The drive of the motor A is determined by, for example, the distribution ratio between the vehicle speed and the engine that is predetermined by the accelerator opening degree, and the battery 13 is further limited in output. When decelerating, the battery 1
Maximum regeneration shall be performed within the regeneration limit of 3.

Then, in step S80, the engine output amount is determined according to the calculated power generation demand.

If the ignition key is kept on, the process returns to step S20 to repeat the above process.

Next, the processing by the BCU 21 will be described.

When activated from the HVCU 23, the BCU 21 first initializes the internal RAM. In addition, B
Internal RAM with backup function added to CU21
It is assumed that the current integrated value I at the time of stopping the previous vehicle operation, the current SOC, and the like are stored even during the initialization process.

Then, in step S110, the current value i and the voltage value v are input to the BCU 21 from the current sensor 17 and the voltage sensor 15, respectively.

Then, in step S120, a battery regeneration limit value and an output limit value representing the limit value of the power that can be input to and output from the battery 13 during regeneration and output are calculated.

Then, in step S130, the current S
Calculate OC. That is, the current capacity Iref capable of discharging the fully charged battery 13 when it is new, the current integrated value I, the offset value I0 of the integrated current value (backed up initial value), the current value detected by the current sensor 17 Based on i, the current SOC is

[Equation 1]   Current SOC = I / Iref               = {(Σi + I0) / Iref} × 100 [%] (1) Becomes

Then, in step S140, the target SO
In order to calculate C, a subroutine after step S210 shown in FIG. 3 is called and executed.

Turning to FIG. 3, in step S210, the current value i and the voltage value v input from the current sensor 17 and the voltage sensor 15 respectively, and the open circuit voltage E of the battery calculated based on the current value i and the voltage value v. , Based on the internal resistance r of the battery, the output power P of the battery is

[Number 2] P = iv = i (E- v) / r = - a - {i (v-E / 2) 2 / r} + E 2 / 4r (2) (v 2 -Ev) / r = .

The theoretical maximum output power Pmax, which represents the maximum output power that can be obtained from the battery alone, is v = E / 2.

## EQU3 ## Pmax = E ² / 4r (3), which is uniquely determined.

However, it is general to calculate the maximum output power Pmax by using the minimum guaranteed voltage Vmin that the motor can normally output. That is, the minimum guaranteed voltage Vmi
Substituting n into equation (2) above, the maximum output power Pmax
Shall be calculated.

Then, in step S220, the reference value Pref representing the maximum output power also has a map for the SOC, and the reference value Pref corresponding to the SOC,
The output reduction rate dp is calculated by comparing the maximum output power Pmax.

[0048]

## EQU00004 ## dp = Pmax / Pref.ltoreq.1 (4) Then, in step S230, the capacity reduction rate dc representing the deterioration state of the current capacity is calculated from the output reduction rate dp. That is, as shown in FIG. 4, assuming that the new capacity = 1 and the capacity ratio at the time of deterioration is the capacity decrease rate dc,

Dc = f (dp) (5) In step S230, if a plurality of correlation maps that can be referred to in accordance with the temperature state are provided, the temperature t detected by the temperature sensor 19 can be used. By selecting the correlation map, the temperature-corrected capacity decrease rate dc can be obtained.

Then, in step S240, the target SOC is corrected and corrected based on the capacity decrease rate dc. That is,
If the median value of the usable range of the SOC that the battery 13 has when it is new is set as the initial target SOC, for example, 50%, the target SOC is

[Equation 6]   Target SOC = 100− (100−initial target SOC) × dc             = 50 × dc (6) Becomes

Then, in step S250, the maximum output power is calculated based on the maximum output power Pmax, the output reduction rate dp, and the capacity reduction rate dc with reference to the reference map for the output power-SOC at the time of new article shown in FIG. The maximum outputable SOC that represents the SOC that can be withdrawn is calculated.

First, the value obtained by dividing the maximum output power Pmax obtained in step S210 by the output reduction rate dp is P1.
Fixed as

## EQU7 ## P1 = Pmax / dp (7) is calculated. Here, referring to the reference map shown in FIG.
The SOC corresponding to 1 is obtained, and S that takes into account the output decrease
OC1 is obtained.

Further, the SOC1 is corrected by multiplying it by dc to obtain the maximum outputable SOC in the current deterioration state,

[Equation 8]   Maximum output possible SOC = SOC1 × dc (8) Is obtained.

Incidentally, in step S250, as shown in FIG.
The maximum outputtable SOC in the current deterioration state corresponding to the maximum output power Pmax was obtained using the reference map shown in FIG.
When each point (SOC, input / output available power P) is corrected using Equations 7 and 8, the charge / discharge characteristics after deterioration can be obtained as shown in FIG.

Here, in step S260, in order to determine whether or not the deterioration state of the battery 13 is equal to or higher than a predetermined state, the difference value obtained by subtracting the target SOC from the maximum outputtable SOC is larger than the predetermined value k. Determine whether or not.
The predetermined value k is set to 15%, for example. When this difference value is larger than the predetermined value k, the process proceeds to step S270. On the other hand, this difference value is a predetermined value k
If it is not larger than, the process proceeds to step S280.

Then, in step S270, since the deterioration state of the battery 13 has not progressed so much from the time of new product, the target SOC obtained in step S240.
Is output to the HVCU 23 as it is.

On the other hand, in step S280, the battery 1
Since the deterioration state of 3 is in progress, the target SOC is based on the maximum outputtable SOC and the predetermined value k.

## EQU9 ## Target SOC = maximum output possible SOC-k (9) is corrected, and this target SOC is output to HVCU 23. After that, the process returns to step S110 and the process is repeated.

Therefore, by executing steps S270 and S280, the range from the maximum outputable SOC to the target SOC is set so that at least 15% or more can be secured.

As shown in FIG. 6, the deteriorated battery 13
With respect to the discharge performance and the charging performance regarding the SOC, the usable range of the SOC in which the input / output power is within the range of 16 to 25 (kW) is 44 to 74%, which is higher than that of the conventional SOC.
The usable range of can be expanded about three times.

As a result, when the parallel hybrid vehicle 1 is stopped by a signal or the like, the accelerator pedal 3
Even when 1 is depressed, it is not necessary to drive the engine 3 to start the vehicle, and it is possible to obtain the output power sufficient to start the vehicle only with the drive torque of the motor 5. As a result, maximum fuel efficiency can be obtained even when the battery deteriorates.

In this embodiment, the case of applying to the parallel type hybrid vehicle has been described.
The present invention is not limited to such a case, and can be similarly applied to a serial type hybrid vehicle. A serial hybrid vehicle detects the state of charge of the battery, and when the state of charge of the battery drops below the target value, the power consumption of the battery is suppressed to generate electricity to charge the battery, and the state of charge of the battery rises above the target value. Then, control is performed so that charging by power generation is stopped and the restriction on the power consumption of the battery is released. In this case, the target value is modified based on the state of deterioration of the battery, and the state of charge of the battery is compared with this target value to control the operation of the power generation mechanism. Fuel efficiency performance can be brought out.

[Brief description of drawings]

FIG. 1 is a diagram showing a system configuration of a hybrid vehicle 1 to which a hybrid vehicle according to an embodiment of the present invention can be applied.

FIG. 2 is a flowchart for explaining the operation of HVCU23 and BCU21.

FIG. 3 is a flowchart for explaining the operation of BCU 21.

FIG. 4 is a correlation map showing a correlation between an output reduction rate and a capacity reduction rate.

FIG. 5 is a reference map used to calculate a maximum outputable SOC.

FIG. 6 is a graph showing charge / discharge characteristics at the time of new article and after deterioration.

FIG. 7 is a graph showing conventional charge / discharge characteristics at the time of new article and after deterioration.

[Explanation of symbols]

1 hybrid vehicle 3 engine 5 Motor A 7 Motor B 9 Inverter A 11 Inverter B 13 battery 15 Voltage sensor 17 Current sensor 19 Temperature sensor 21 BCU 23 HVCU 31 accelerator pedal 33 vehicle speed sensor

Front page continuation (51) Int.Cl. ⁷ Identification code FI B60L 11/12 B60L 11/12 F02D 29/02 F02D 29/02 D 29/06 29/06 H G01R 31/36 G01R 31/36 A (58 ) Fields surveyed (Int.Cl. ⁷ , DB name) B60L 11/14 B60K 6/04 B60L 3/00 B60L 11/12 F02D 29/02 F02D 29/06 G01R 31/36

Claims (2)

(57) [Claims] 1. An engine that generates a running torque, a battery, a motor that receives a power supply from the battery to generate a running torque, a charge state detection unit that detects a charge state of the battery, and a detected battery charge. In a parallel type hybrid vehicle having a control means that distributes a power source that generates a running torque by comparing the state with a target charge state value , a deterioration state determination means for determining the deterioration state of the battery, and a deterioration state of the battery A correction unit that corrects the target state of charge value based on the battery, and the deterioration state determination unit can output the battery based on the current and voltage of the battery.
Maximum output power calculating means for calculating the maximum output power, the calculated maximum output power, and the fact that the battery is fully charged when new
The maximum output power is compared with the reference value of the maximum output power.
Output reduction rate calculation that calculates the output reduction rate that indicates the deterioration state of
Output means and capacity indicating the deterioration state of current capacity according to this output reduction rate
A capacity decrease rate calculating means for calculating a decrease rate, wherein the correcting means determines a target charging state value of the first charge state value according to the calculated capacity decrease rate.
First correction value calculating means for calculating one correction value, and the calculated maximum output power, output reduction rate, and capacity reduction
Maximum output power can be derived based on rate
Maximum output that indicates the state of charge Maximum output to calculate the state of charge value
Outputtable charge state value calculating means, and a value obtained by subtracting the first correction value from the maximum outputtable charge state value
Is less than the specified value, the maximum output possible state of charge
The value obtained by subtracting this predetermined value from the value is used as the target state of charge value,
The value obtained by subtracting the first correction value from the maximum output possible charge state value is
If it is larger than the predetermined value, the first correction value is set to the target value.
And a second correction value calculating means for calculating a power state value . 2. An engine, a power generation mechanism driven by the engine, a battery charged by the power generation mechanism, and a motor that receives running power from the battery to generate running torque.
In a serial hybrid vehicle having a charge state detection means for detecting the charge state of the battery and a control means for controlling the operation of the power generation mechanism by comparing the detected charge state of the battery with a target charge state value , deterioration of the battery A deterioration state determining means for determining the state, and a correcting means for correcting the target state of charge value based on the deterioration state of the battery, the deterioration state determining means , based on the current and voltage of the battery, Can be output
Maximum output power calculating means for calculating the maximum output power, the calculated maximum output power, and the fact that the battery is fully charged when new
The maximum output power is compared with the reference value of the maximum output power.
Output reduction rate calculation that calculates the output reduction rate that indicates the deterioration state of
Output means and capacity indicating the deterioration state of current capacity according to this output reduction rate
A capacity decrease rate calculating means for calculating a decrease rate, wherein the correcting means determines a first target state of charge value according to the calculated capacity decrease rate.
First correction value calculating means for calculating one correction value, and the calculated maximum output power, output reduction rate, and capacity reduction
Maximum output power can be derived based on rate
Maximum output that indicates the state of charge Maximum output to calculate the state of charge value
Outputtable charge state value calculating means, and a value obtained by subtracting the first correction value from the maximum outputtable charge state value
Is less than the specified value, the maximum output possible state of charge
The value obtained by subtracting this predetermined value from the value is used as the target state of charge value,
The value obtained by subtracting the first correction value from the maximum output possible charge state value is
If it is larger than the predetermined value, the first correction value is set to the target value.
A hybrid vehicle , comprising: a second correction value calculating means for calculating a power state value .