JPH10341502A - Generator controlling device for hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control a generator driven by an engine without causing it to delay starting its operation even when the temperature of a battery changes or when the battery is deteriorated. SOLUTION: After the charging and discharging currents and terminal voltage of a battery are detected (Step 101), its maximum dischargeable current and maximum tolerable current in that state are calculated (Step 102) from its detected charging and discharging currents and terminal voltage. Then, the maximum dischargeable current is compared with the maximum tolerable one (Step 103). When it is determined that both values have become equal, a generator starts to generate power in Step 105.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a generator control device for a hybrid electric vehicle having a motor and an engine as driving sources for a vehicle, and more particularly to a generator for charging a chargeable / dischargeable battery which is a power source for a motor. Related to a control device.

[0002]

2. Description of the Related Art As a generator for charging a chargeable / dischargeable battery mounted on a hybrid electric vehicle, that is, a control device for an engine-driven generator, for example, those disclosed in JP-A-6-178405 and JP-A-6-178405 are disclosed. There is one disclosed in Japanese Patent No. -178406. The former control device limits the output of the motor to the power generated by the engine-driven generator when the remaining discharge capacity (SOC) of the battery drops to a predetermined value during operation of the engine-driven generator, and sets the other predetermined value. When it has decreased to such a level, control such as increasing the power generated by the engine-driven generator is performed. In other words, the operation of the engine-driven generator is started in accordance with the state of charge of the battery.

The latter control device calculates an average value of power consumption by driving means such as a motor and an inverter after the start of driving, and sets a relatively high power generation start point when the obtained average value is relatively large. In addition, the output power of the engine-driven generator is controlled in accordance with the obtained average value. In short, the control is performed by changing the SOC for starting the operation of the generator in accordance with the power consumption.

[0004] These conventional control devices control the generator based on the state of charge of the battery as described above, and have the effect of preventing deep discharge of the battery and prolonging the service life. If the battery changes or the battery deteriorates, the operation start point of the generator is shifted, and there is a problem that the battery is overdischarged or the output of the driving means is limited.

[0005]

A first problem to be solved by the present invention is that even if the battery temperature changes or the battery deteriorates, the operation start point of the engine-driven generator does not shift and the generator does not shift. Is to perform the control.
A second problem to be solved by the present invention is to control a generator so as to obtain an optimum power generation output in addition to the first problem.

[0006]

In order to solve the first problem, a charge / discharge current and a terminal voltage of a battery detected by sampling and, for example, a predetermined maximum voltage and a minimum voltage of the battery are determined. The maximum acceptable current and the maximum dischargeable current are calculated respectively, and control is performed so that the generator is started when the maximum acceptable current becomes the same as the maximum dischargeable current. As a result, charging is started before overdischarge occurs.
At that time, in order to further solve the second problem, by calculating a target generated power based on the calculated maximum receivable current, and controlling the generator to be the calculated target generated power, The required power can be supplied to the motor in a wide range.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to examples. FIG. 1 shows a configuration of a hybrid electric vehicle according to a first embodiment of the present invention. The hybrid electric vehicle includes a motor (MTR) 10 and an engine (ENG) 1 as drive sources. The motor 10 is, for example, a three-phase AC motor. DC power from the chargeable / dischargeable battery 5 is converted into three-phase AC power by an inverter (INV) 9 and supplied to a three-phase AC motor 10. Engine 1
Is a driving source of the vehicle and also a driving source of the generator 2. That is, the output shaft of the engine 1 is connected directly or indirectly to the generator 2, and when the engine 1 rotates, generated power is output from the generator 2. Therefore, the engine 1 and the generator 2 constitute an engine-driven generator. The generator 2 is, for example, a three-phase AC generator. The output of generator 2,
That is, the three-phase AC power is converted into DC power by the rectifier 3 and supplied to the chargeable / dischargeable battery 5.

The vehicle controller 11 is a controller for controlling the inverter 9 and the like. Vehicle controller 1
1 inputs a signal indicating a battery state from the battery controller 8 together with a vehicle signal indicating an accelerator operation, a brake operation, and the like of a driver, and an inverter 9 based on these signals.
Control the operation of. The inverter 9 is composed of a predetermined number of switching elements, and the output torque of the motor 10 can be controlled by controlling the switching elements. By performing such control, the vehicle controller 11 causes the motor 10 to generate an output torque corresponding to the accelerator operation or the brake operation of the driver.

The battery controller 8 inputs the charging / discharging current of the battery 5 and the inter-terminal voltage detected by the current detector (I detection) 6 and the voltage detector (V detection) 7, respectively. Is calculated, and the power generation of the engine-driven generator is started via the power generation controller 4 when a predetermined condition is satisfied. Since the battery 5 is charged while the engine-driven generator is operating, the running distance can be extended by operating the engine-driven generator when the battery 5 has been discharged to some extent. .

When the engine-driven generator is operating, the power generation controller 4 monitors the rotation speed of the engine 1 and the output voltage and current of the generator 2 while keeping the output power of the generator 2 constant. It controls so that it becomes. This control
For example, control of the throttle opening of the engine 1 or the generator 2
By controlling the field current.

FIG. 2 is a flowchart showing the control operation of this embodiment. The operation shown in FIG. 2 is mainly executed by the battery controller 8. When an ignition switch (not shown) is first turned on, the battery controller 8 detects a charging / discharging current I and a terminal voltage V of the battery 5 at predetermined time intervals, that is, at every sampling time at step 101.

Next, at step 102, the maximum dischargeable current and the maximum acceptable current are calculated based on the detected charge / discharge current I and terminal voltage V. A method for calculating these currents will be described with reference to FIG. The values of the plurality of charge / discharge currents I and the terminal voltage V detected within a certain period of time are plotted on the vertical axis as the voltage axis,
When plotted on a graph with the horizontal axis representing the current axis, the distribution is in an oblique ellipse rising upward. When this is approximated to a linear expression, an oblique line rising leftward is obtained. In this case, the discharge current is given as positive, and the charging current or receiving current is given as negative. Then, assuming that the internal resistance of the battery in the state where the above sampling is performed is R, and K is a constant given from the characteristics of the battery, the relationship between the terminal voltage V of the battery and the charging / discharging current I is expressed by Expression (1). become. V = -IR + K (1)

In FIG. 3, the upper broken line parallel to the current axis indicates the full charge voltage of the battery, ie, the maximum voltage Vmx, and the lower broken line indicates the lower discharge voltage, ie, the minimum voltage Vmn of the battery.
Therefore, the point on the current axis corresponding to the point at which the hatched line representing Expression (1) reaches the line indicating the maximum voltage Vmx is the maximum acceptable current Ic, and the hatched line representing Expression (1) represents the minimum voltage Vmn. The point on the current axis corresponding to the point at which the line is reached is the maximum dischargeable current Id. Therefore, the maximum acceptable current Ic is represented by equation (2), and the maximum dischargeable current Id is represented by equation (3). Ic = (K−Vmx) / R (2) Id = (K−Vmn) / R (3)

Incidentally, the internal resistance R of the battery is simply calculated because it is the slope of the oblique line rising leftward in FIG. Once the value of the resistor R is determined, the value of the constant K can be easily calculated by applying the voltage and current values at a certain sampling time to the equation (1). Therefore, the battery controller 8 calculates the maximum acceptable current Ic and the maximum dischargeable current Id by applying the values of the internal resistance R and the constant K to Expressions (2) and (3).

In step 103, the maximum dischargeable current calculated in step 102 is compared with the maximum acceptable current. Since the maximum acceptable current is calculated with a negative value of Ic in equation (2), the absolute value of Ic and Id are compared. As a result of the comparison, the maximum acceptable current, ie, I
If the absolute value of c is equal to or greater than the maximum dischargeable current Id, the process proceeds to step 105; otherwise, the process returns to the first step 101.

In step 105, the battery controller 8
Sends a power generation start command signal to the power generation controller 4. Then, the power generation controller 4 starts the engine 1 to control the throttle and adjusts the field current of the generator 2 so that the engine-driven generator outputs a predetermined power generation output W. Therefore, the hybrid electric vehicle runs while generating the power output W by driving the generator 2 with the engine 1 and charging the battery 5.

In this embodiment, the current detector (I detection) 6
And a voltage detector (V detection) constitute a means for detecting the charge / discharge current and terminal voltage of the battery in the present invention, and step 10
Steps 103 and 103 comprise means for calculating the maximum dischargeable current and maximum acceptable current of the battery in that state from the detected charge / discharge current and terminal voltage of the battery.
And 105 constitute means for starting power generation of the generator when the values of the maximum dischargeable current and the maximum acceptable current become equal, respectively.

As described above, in this embodiment, when the maximum dischargeable current becomes equal to the maximum acceptable current, power generation is started and the battery is charged. Therefore, it is possible to set an optimum power generation start point of the generator.

Next, a second embodiment of the present invention will be described with reference to the flowchart of the control operation of FIG. The operation shown in FIG. 4 is a control operation of the first embodiment of the present invention.
Steps 101 to 103 in the flowchart of FIG. However, unlike the case of FIG. 2, if the maximum acceptable current is equal to or greater than the maximum dischargeable current in step 103, the process proceeds to step 104. In this step 104, the battery controller 8 determines the target output W of the engine generator from the known relationship between the maximum chargeable / dischargeable current (maximum acceptable current = maximum dischargeable current) and the generator output as shown in FIG. calculate.

That is, as shown in FIG. 5, the charge / discharge current of the battery in the situation where the maximum acceptable current is the same as the maximum dischargeable current, ie, the maximum chargeable / dischargeable current is 0 (A) to 30.
When the maximum chargeable / dischargeable current is small in the combination of the battery 5 and the generator 2 that changes in the range up to 0 (A), the target generator output is set to the maximum output of 30 (KW), and 300
In the range close to (A), the corresponding generator output, that is, the target generated power W is calculated according to a linear expression that is a relational expression representing a thick oblique line. After the target generated power W is calculated based on FIG. 5, the process proceeds to the power generation step 105. This allows
The hybrid electric vehicle drives the generator 2 by the engine 1 to generate a power output W, and runs while charging the battery 5. Other configurations are the same as the previous embodiment. In this embodiment, steps 104 and 105 constitute a means for controlling the power generation output of the present invention by the maximum chargeable / dischargeable current when the maximum dischargeable current and the maximum acceptable current become equal.

In this embodiment, in addition to the same effects as those of the first embodiment, by increasing the generator output when the chargeable / dischargeable power is small, the power required for the motor in a wide range of the SOC of the battery can be obtained. Can be supplied.

[0022]

As described above, according to the present invention, the maximum dischargeable current and the maximum acceptable current are calculated based on the charge / discharge current and the terminal voltage of the battery, and when the values are equal, the generator starts to generate power. In this case, the optimum power generation start point is set, so that overdischarge of the battery can be prevented. Further, remarkable decrease in the remaining discharge capacity SOC of the battery regardless of the battery temperature or the deterioration state of the battery is suppressed. As a result, the mileage can be extended by charging the battery.
The operation can be performed stably irrespective of the driver and the driving environment, and the so-called deep discharge of the battery is prevented, so that the life of the battery is prolonged. In addition, since the control of the generator does not depend on the temperature or the deterioration state of the battery, it is not necessary to measure the temperature or the deterioration state of the battery.

Further, by controlling the power generation output based on the current value, for example, increasing the target power generation when the maximum chargeable / dischargeable current is small, the motor can be driven in a wide range of the remaining discharge capacity of the battery. The required power can be supplied.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control operation according to the first embodiment.

FIG. 3 is a diagram illustrating a relationship between a charge / discharge current of a battery and a terminal voltage, and a method of calculating a maximum acceptable current and a maximum dischargeable current.

FIG. 4 is a flowchart illustrating a control operation according to a second embodiment.

FIG. 5 is a diagram showing a relationship between a maximum chargeable / dischargeable current and a generator output in the second embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 Generator 3 Rectifier 4 Power generation controller 5 Rechargeable battery 6 Current detector 7 Voltage detector 8 Battery controller 9 Inverter 10 Motor 11 Vehicle controller

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI H02J 7/00 H02J 7/00 P

Claims (2)

[Claims] 1. A chargeable / dischargeable battery, driving means for receiving a supply of power from the battery to generate a driving force for a vehicle, and a generator for starting operation according to a command and charging the battery with the output power. Means for detecting the charge / discharge current and terminal voltage of the battery, the maximum dischargeable current and the maximum acceptance of the battery in that state from the detected charge / discharge current and terminal voltage of the battery. A generator control device for a hybrid electric vehicle, comprising: means for calculating a possible current; and means for starting power generation of the generator when the maximum dischargeable current and the maximum acceptable current become equal. 2. The hybrid electric machine according to claim 1, further comprising means for controlling the power generation output of the generator by the maximum receiving current value when the maximum dischargeable current and the maximum acceptable current value become equal. Automotive generator control.