JP2020104646A - Power generation control device - Google Patents

Abstract

To provide a power generation control device which is improved so as to effectively bring out performance of a battery having temperature dependency of charging and discharging power.SOLUTION: A low temperature battery temperature rising control processing can repeat charging and discharging of a battery 12 alternately within a range between a preset battery dischargeable power quantity (that is, Wout) and a preset battery chargeable power quantity (that is, Win) when a temperature of a battery 12 is lower than a first standard temperature α. Thereby, a temperature of the battery 12 can be raised quickly. When the temperature of the battery 12 is higher than a second standard temperature β according to high temperature battery temperature suppression control processing, an engine 10 is set as a preset quasi-stationary operation. The quasi-stationary operation is such an operation as to moderate a transient operation of the engine 10 and, thereby, to moderate charging/discharging of the battery 12. According to the high temperature battery temperature suppression control processing, it can be suppressed that battery temperature becomes excessively higher.SELECTED DRAWING: Figure 9

Description

The present invention relates to a power generation control device.

Conventionally, a hybrid system having a battery protection operation is known as described in, for example, Japanese Patent Application Laid-Open No. 10-14296. The technology according to the above publication is a series-type hybrid system, which is divided into cases of normal power generation and battery protection, and control is performed according to each case.

During normal power generation, if it is necessary to make the power generation amount of the power generator follow the motor output, the power generation amount is controlled based on the engine rotation speed by setting the power generator to constant torque control. At the time of battery protection, charging/discharging of the battery is prohibited, while the engine is controlled to a constant speed, so that the power generation amount of the generator is set according to the required output of the motor.

JP, 10-14296, A

However, in the above-mentioned conventional technique, the battery charge is only prohibited if the battery temperature is detected and protection is required. Also, the rate of rise and fall of the battery temperature will be the consequence of that point. Further, the above publication does not refer to the case where the battery is at a low temperature. As described above, the conventional technique still leaves room for improvement from the viewpoint of effectively drawing out the performance of the battery having the temperature dependence of the charge/discharge power.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an improved power generation control device capable of effectively drawing out the performance of a battery having temperature dependence of charge/discharge power. To do.

The power generation control device according to the present invention,
A power generation control device for controlling a hybrid system including an engine, a generator, and a battery,
When the temperature of the battery is lower than a predetermined first reference temperature, charging and discharging of the battery are alternately performed within a range of a preset battery discharge power amount and a preset battery charge power amount. Low temperature control means to repeat
When the temperature of the battery is higher than the second reference temperature which is higher than the first reference temperature and the temperature of the battery is higher than the first reference temperature, the engine is set to a predetermined predetermined operation, and the predetermined operation suppresses the charge/discharge fluctuation amount of the battery. High temperature control means that is an operation of adjusting the amount of power generation of the engine so that
Equipped with.

According to the present invention, the battery temperature can be raised early at low temperatures, and the rise in battery temperature at high temperatures can be suppressed. As a result, the chargeable/dischargeable range can be secured by keeping the battery temperature within the proper range, and the battery performance can be effectively brought out.

1 is a diagram showing a configuration of a hybrid vehicle equipped with a power generation control device according to an embodiment. It is a graph which shows the relationship between a battery output possible range and battery temperature. 5 is a graph for explaining an operation performed by the power generation control device according to the embodiment. 6 is a time chart for explaining an operation performed by the power generation control device according to the embodiment. It is a figure for demonstrating the problem which arises with the relationship between a battery input/output electric energy and a battery temperature. 6 is a time chart for explaining an operation performed by the power generation control device according to the embodiment. 5 is a graph for explaining an operation performed by the power generation control device according to the embodiment. 3 is a flowchart of a routine executed by the power generation control device according to the embodiment. 3 is a flowchart of a routine executed by the power generation control device according to the embodiment. 3 is a graph for explaining an engine operating point in the power generation control device according to the embodiment. 3 is a graph for explaining an engine operating point in the power generation control device according to the embodiment. 5 is a graph for explaining an operation performed by the power generation control device according to the embodiment.

FIG. 1 is a diagram showing a configuration of a hybrid vehicle equipped with a power generation control device according to an embodiment. FIG. 1 is an explanatory diagram schematically showing the system configuration of a SHEV (series hybrid electric vehicle). As shown in FIG. 1, the SHEV includes an engine 10 for driving a generator 11, a generator 11 driven by the engine 10 to generate electric power, a battery 12 for storing and supplying electric energy, and a vehicle A motor 13 for driving that is used for energy regeneration during driving and deceleration, a drive system 14 such as a transmission that transmits the rotation of the motor 13 to the driving wheels 15, a speed reducer, an engine 10, a generator 11, a motor 13, etc. And a control unit 16 for controlling the.

The control unit 16 executes various controls based on input values such as various sensor values. The input value input to the control unit 16 includes a vehicle speed read from a vehicle speed sensor (not shown) that detects the vehicle speed, a battery voltage read from a voltage sensor (not shown) added to the battery 12, and a battery 12 The temperature of the battery 12 read from an additional temperature sensor (not shown), the crank angle signal from the engine 10, the generator torque from the generator 11, the accelerator opening from the accelerator (not shown), and the transmission. From the shift position signal and the like. Various controls performed by the control unit 16 include input/output of the motor 13, charge/discharge of the battery 12, output of the generator 11, start/stop of the engine 10 for driving the generator 11, and rotation by a throttle valve. Control of speed etc. is included.

FIG. 2 is a graph showing the relationship between the battery input/output possible range and the temperature of the battery 12. The vertical axis of FIG. 2 is for indicating the battery input/output possible range, and the output, that is, the amount of electric discharge for the plus side in the upper part of FIG. The amount of charging power is indicated on each side. The horizontal axis of FIG. 2 is the temperature of the battery 12, the left side of FIG. 2 is the extremely low temperature, and the higher the right side of FIG. 2, the higher the temperature.

FIG. 2 shows a solid line graph showing the battery dischargeable power amount Wout according to the temperature of the battery 12 and a solid line graph showing the battery chargeable power amount Win according to the temperature of the battery 12. The range sandwiched between these two graphs is the range of power that can be input/output by the battery. That is, an appropriate power input/output range to/from the battery is determined within a range between Wout and Win at a specific battery temperature.

As is clear from FIG. 2, in the extremely low temperature region and the high temperature region, Wout and Win converge to zero power value. As a result, there is a problem that the battery input/output power range is extremely narrow between the extremely low temperature region and the high temperature region. In the hybrid system, when the battery 12 is at a low temperature or a high temperature, the battery chargeable power amount Win or the battery dischargeable power amount Wout is limited, which may cause difficulty in sufficient power generation.

In the series hybrid system vehicle, the flow of electricity between the engine 10, the traveling motor 13 and the battery 12 can be more freely set and changed. This is because the output of the engine 10 does not directly relate to the drive wheels, and thus the drivability is not affected. In particular, the control itself for raising or lowering the battery temperature can also be controlled by power generation and charging/discharging by the engine 10. As a result, there is an advantage that effective power generation control can be easily realized.

When the temperature of the battery 12 is high, the energy generated by the engine 10 is used for the driving motor 13 and is not used for charging and discharging the battery. Thereby, the deterioration of the battery 12 can be suppressed.

Until the above control is activated, the temperature of the battery 12 may continue to rise depending on the operating conditions, and the temperature of the battery 12 may reach the protection temperature. One of the causes of the problem is that the temperature of the battery 12 is detected and then the protection function (that is, the charge/discharge inhibition function) is activated. Since the operation of prohibiting battery charging/discharging is performed after it is detected that the temperature of the battery 12 is high enough to require protection, there is a problem that a delay occurs when the battery 12 is at a high temperature. Further, the rate of rise and fall of the temperature of the battery 12 depends on the time point, which also causes a delay.

There is also a problem that the energy of the battery 12 cannot be used efficiently. As shown in FIG. 2, the width between the battery chargeable power amount Win and the battery dischargeable power amount Wout becomes narrow between the extremely low temperature and the high temperature. This limits the amount of battery power input/output at extremely low and high battery temperatures, making it difficult to achieve power performance and responsiveness that would have been possible at room temperature at extremely low and high temperatures. There is also the problem that Since the battery input/output range is narrow at extremely low temperatures and high temperatures, the vehicle required power must be realized by the power of the engine 10, and there is also a problem that the engine 10 cannot be operated at a fixed point.

Therefore, in the embodiment, the above problem is dealt with by the two approaches shown in FIG. FIG. 3 is a graph for explaining the operation performed by the power generation control device according to the embodiment. As indicated by two arrows in FIG. 3, if the battery 12 is extremely low, the temperature of the battery 12 is raised quickly, and if the battery 12 is high, the temperature is prevented from further increasing. Particularly, it is preferable that the temperature of the battery 12 does not reach the high protection temperature TH. As a result, the battery 12 can be used effectively and efficiently while preventing deterioration of the battery 12.

FIG. 4 is a time chart for explaining the operation performed by the power generation control device according to the embodiment. FIG. 4 is a diagram for explaining a temperature rise control process of the low-temperature battery 12 for quickly raising the temperature of the battery 12.

Battery charging/discharging can be realized by alternating generation of engine torque and motoring. At this time, by making the engine speed and the throttle opening constant, it is possible to avoid a great deterioration of the air-fuel ratio controllability.

In FIG. 4, the temperature of the battery 12 rises as time passes, so that the interval between the battery chargeable power amount Win and the battery dischargeable power amount Wout is expanded. According to the low temperature processing control according to the embodiment, as shown by the solid line, the interval between the battery chargeable power amount Win and the battery dischargeable power amount Wout can be expanded at an early stage. As shown by the rectangular wave in FIG. 4, in the engine 10, FC (fuel cut) and injection and ignition are alternately repeated at a predetermined cycle to perform periodic battery charge/discharge.

The graph shown by the dotted line in FIG. 4 is a comparative example, and is Win and Wout when the low temperature processing control according to the embodiment is not executed. In the case of this comparative example, it takes time until the battery input/output range is expanded and the battery 12 can be effectively used.

FIG. 5 is a diagram for explaining a problem caused by the relationship between the battery input/output electric energy and the battery temperature. In FIG. 5, z is the battery input/output electric energy. x is a drive request, that is, the output of the drive motor. y is the engine power generation amount. There is a relationship of z=x+y.

If the change in the battery input/output power is large, the battery temperature will rise. As the battery temperature rises, the interval between Wout and Win becomes narrower as described with reference to FIG. As pointed out by the circular frame Q in FIG. 5, the battery input/output electric energy may partially exceed Wout.

The battery temperature has become too high at the time point indicated by the white star P1 in FIG. 5, and from this time point, the system operation state of “drive request=engine request” is entered and the battery input/output is zero. In such a system operating state of "drive request=engine output", the transient operation of the engine is increased, the air-fuel ratio controllability is deteriorated, and emission and fuel consumption are deteriorated. As a result, the advantages of the series hybrid system are lost.

FIG. 6 is a time chart for explaining the operation performed by the power generation control device according to the embodiment. FIG. 6 is a diagram for explaining a high temperature battery temperature suppression control process for suppressing an increase in the temperature of the battery 12. Also in FIG. 6, a graph of x, y, z is shown similarly to FIG. 5, and the relationship of z=x+y is established.

In the embodiment, the engine is changed from the steady operation to the “quasi-steady operation” before the battery temperature reaches the protection temperature by the battery temperature increase estimation. The start point of the quasi-steady operation is represented by a black star P2 in FIG. The quasi-steady operation is an operation in which the output change of the engine is minimum, the battery input/output (charging/discharging) is mitigated, and the rise in the battery temperature is mitigated.

Compare FIG. 5 and FIG. In FIG. 5, the graph z showing the battery input/output power amount (battery charge/discharge power amount) has a large fluctuation range, while the engine power generation amount y is fixed up to the white star P1. Contrary to this, in the quasi-steady operation started from the black star P2 in FIG. 6, the fluctuation range of the graph z showing the battery input/output power amount (battery charge/discharge power amount) is suppressed to be small, and On the other hand, the engine power generation amount y is changed.

Quasi-steady operation does not mean “drive request=engine request”, but “transient-relieved operation”. As a result, the guarantee of power performance, prevention of battery deterioration, and suppression of emission deterioration can be achieved at the same time. Since the air-fuel ratio controllability does not deteriorate significantly, it is possible to suppress adverse effects on emissions and fuel efficiency. Therefore, there is an advantage that the advantages of the series hybrid system are not impaired.

Next, specific control performed by the control unit 16 in the embodiment will be described. FIG. 7 is a graph for explaining the operation performed by the power generation control device according to the embodiment. 8 and 9 are flowcharts of a routine executed by the power generation control device according to the embodiment. The routines of FIGS. 8 and 9 are executed by the control unit 16.

In the routine of FIG. 8, first, the temperature of the battery 12 is estimated (step S100). By the routine of FIG. 8, it is determined whether the temperature of the battery 12 corresponds to the extremely low temperature, the normal temperature, or the high temperature shown in FIG. 7. The extremely low temperature, the room temperature, and the high temperature are defined by a first reference temperature α and a second reference temperature β that are set in advance. First, it is determined whether the temperature of the battery 12 is equal to or lower than a predetermined first reference temperature α (step S101).

If the temperature of the battery 12 is equal to or lower than the first reference temperature α, it is determined that the temperature of the battery 12 is extremely low, and 1 is set in the Battemp_md flag (step S102). If the temperature of the battery 12 exceeds the first reference temperature α, then it is determined whether or not the temperature of the battery 12 is equal to or lower than the predetermined second reference temperature β (step S103). β is a value set higher than α and is a reference temperature for high temperature determination.

If the temperature of the battery 12 is equal to or lower than the second reference temperature β, it is determined that the temperature of the battery 12 is the normal temperature, and 0 is set to the Battemp_md flag and the Battemp_h flag (step S104). If the temperature of the battery 12 exceeds the second reference temperature β, the Battemp_h flag is set to 1 (step S105). After execution of any of steps S102, S104, and S105, the routine of FIG. 8 ends.

In the routine of FIG. 9, first, it is determined whether or not the Battemp_md flag is set to 1 in order to determine whether or not the battery 12 has an extremely low temperature (step S200). If the Battemp_md flag is 1, the temperature rise control of the battery 12 is performed as described in FIG. 4 (step S201).

If the Battemp_md flag is not 1, then it is determined whether or not the Battemp_h flag is set to 1 in order to determine whether the battery 12 is at room temperature (step S202).

(Steady operation)
If the Battemp_hd flag is not 1, "steady operation" for performing normal series hybrid control is performed (step S203). In step S203, the steady engine request PE schematically shown in FIG. 10 is calculated. FIG. 10 is a graph for explaining operating points of the engine 10 in the power generation control device according to the embodiment. This is the basic control of a series hybrid system. According to various conditions such as SOC, fixed point operating conditions such as star A and star B in FIG. 10 are calculated, and the steady operation of the engine 10 is performed under the fixed point operating conditions.

(Quasi steady operation)
If the Battemp_hd flag is 1, the “quasi-steady operation” is performed as described with reference to FIGS. 5 and 6 (step S204). In step S204, the quasi-steady engine request PE schematically shown in FIG. 11 is calculated. FIG. 11 is a graph for explaining operating points of the engine 10 in the power generation control device according to the embodiment. At the time of high temperature determination, the engine request PE is calculated by the temperature coefficient θ.

FIG. 12 is a graph for explaining the operation performed by the power generation control device according to the embodiment. In relation to the quasi-steady operation, FIG. 12 shows an example of the relationship between the temperature coefficient θ and the estimated temperature value. Θ is determined within the range of 0 to 1.0, and the higher the estimated temperature value is, the higher the temperature coefficient θ is calculated. The quasi-steady PE request is the driving force request (vehicle required power) multiplied by the temperature coefficient θ.

In the quasi-steady operation, as shown in FIG. 11, the engine rotation speed is determined within a range that does not deviate from the fuel consumption line (fuel consumption contour line) as indicated by the operating point of the star C and the arrows on both sides thereof. After execution of any of steps S201, S230, and S204, the routine of FIG. 9 ends.

As described above, in the low temperature battery temperature increase control process according to the embodiment, when the temperature of the battery 12 is lower than the first reference temperature α, the preset battery dischargeable electric energy (that is, Wout) is set. The charging and discharging of the battery 12 can be alternately repeated within the range of the battery chargeable electric energy (that is, Win) set in advance. Thereby, the temperature of the battery 12 can be raised quickly.

Further, according to the embodiment, when the temperature of the battery 12 is higher than the second reference temperature β by the high temperature battery temperature suppression control process, the engine 10 is set to the quasi-steady operation in advance. The quasi-steady operation is an operation in which the charge/discharge of the battery 12 is eased by mitigating the transient operation of the engine 10. The battery temperature suppression control process at high temperature can suppress the battery temperature from becoming excessively high.

10 engine 11 generator 12 battery 13 motor 14 drive system 15 drive wheels 16 control unit Win battery chargeable power amount Wout battery dischargeable power amount α first reference temperature β second reference temperature TH protection temperature

Claims (1)

A power generation control device for controlling a hybrid system including an engine, a generator, and a battery,
When the temperature of the battery is lower than a predetermined first reference temperature, charging and discharging of the battery are alternately performed within a range of a preset battery discharge power amount and a preset battery charge power amount. Low temperature control means to repeat
When the temperature of the battery is higher than the second reference temperature which is higher than the first reference temperature and the temperature of the battery is higher than the first reference temperature, the engine is set to a predetermined predetermined operation, and the predetermined operation suppresses the charge/discharge fluctuation amount of the battery. High temperature control means that is an operation of adjusting the amount of power generation of the engine so that
A power generation control device.

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