JP2001211507A - Control apparatus of hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a regenerative energy efficiency of a hybrid vehicle at deceleration. SOLUTION: The control apparatus differentiates a target state of charge TSOC at a constant-speed driving from that of decelerating driving, and sets a target state of charge for the steady-speed driving lower (TSOCL) and that of the reduced-speed driving higher (TSOCH) (21). The apparatus calculates a target charge current for a high voltage battery after detecting a state of charge of the high voltage battery and compare the actual state of charge SOC with the target state of charge TSOC. It further calculates a target generating current for a generating motor 2 (27) after detecting an electric load current supplied from a low voltage battery to the load of vehicle (26) and integrates the electric load current with the target charge current. It then controls an amount of electric generation of the generating motor 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention provides an internal combustion engine and an electric motor powered by a high-voltage battery as driving sources for driving a vehicle. The present invention relates to a control device for a hybrid vehicle that uses an electric motor as a generator to charge the high-voltage battery and a low-voltage battery for a vehicle-mounted electric load.

[0002]

2. Description of the Related Art In recent years, as disclosed in Japanese Patent Application Laid-Open No. H11-22501, an internal combustion engine (gasoline engine) and an electric motor using a high-voltage battery as a power source are used as driving sources for running a vehicle. The development of hybrid vehicles equipped with them is underway.

[0003] In such a hybrid vehicle, the electric motor is used as a generator to charge a high-voltage battery and a low-voltage battery for an on-vehicle electric load under predetermined operating conditions including deceleration operation. .

[0004] Here, the amount of power generated by the electric motor (generated current) is detected by detecting the charge level of a high-voltage battery and controlled to be at a full charge level.

[0005]

However, even if an attempt is made to regenerate energy during deceleration operation, if the high-voltage battery is already at the full charge level, no power will be accepted, so that energy regeneration cannot be performed effectively. Not only that, the high-voltage battery is overcharged, so that the deterioration of the battery is accelerated or the deceleration (deceleration G) becomes too large, giving the driver an uncomfortable feeling.

When an inexpensive lead-acid battery is used as a high-voltage battery instead of an expensive lithium-ion battery, nickel-metal hydride battery, or the like, the lead-acid battery is particularly liable to be deteriorated by overcharging. It is essential to take measures to prevent charging.

SUMMARY OF THE INVENTION In view of such circumstances, it is an object of the present invention to improve energy regeneration efficiency during deceleration operation and to reliably prevent overcharging.

[0008]

According to the present invention, an internal combustion engine and a driving source for driving a vehicle are provided.
An electric motor having a high-voltage battery as a power source, and under predetermined operating conditions including a time of deceleration operation, using the electric motor as a generator, the high-voltage battery and a low-voltage battery for a vehicle-mounted electric load. In the control device for a hybrid vehicle, the power generation amount feedback control means for detecting the charge level of the high-voltage battery and performing feedback control of the power generation amount of the electric motor so as to reach the target charge level is further provided. A target charge level switching means for making the target charge level different between the operation and the deceleration operation is provided.

[0009] The invention according to claim 2 is characterized in that the target charge level during steady operation is set lower than the target charge level during deceleration operation. The invention according to claim 3 is characterized in that the target charge level during the deceleration operation is set to be equivalent to the full charge level.

[0010] In the invention according to claim 4, the power generation amount feedback control means includes a charge level detection means for detecting a charge level of the high voltage battery, and an actual charge level which is compared with a target charge level. Target charging current calculating means for calculating a target charging current to the battery; electric load current detecting means for detecting an electric load current supplied to the vehicle-mounted electric load from the low-voltage battery; the target charging current and the electric load A target power generation current calculation means for calculating a target power generation current by the electric motor by adding a current; and a power generation amount control means for performing power generation control of the electric motor so as to obtain the target power generation current. It is characterized by being performed.

The invention according to claim 5 is characterized in that a lead-acid battery is used as the high-voltage battery.

[0012]

According to the first aspect of the present invention, when the charge level of the high-voltage battery is detected and the amount of electric power generated by the electric motor is feedback-controlled so as to reach the target charge level, deceleration during steady-state operation is reduced. By making the target charge level different from that during driving, particularly as in the invention according to claim 2,
By setting the target charge level during steady-state operation to be lower than the target charge level during deceleration operation, control is performed so that the battery does not become fully charged during steady-state operation, and the empty capacity for energy regeneration during deceleration operation is secured. Energy regeneration during deceleration operation can be made more effective.

Further, by setting the target charge level during deceleration operation to be equivalent to the full charge level as in the invention according to claim 3, sufficient energy regeneration can be performed during deceleration operation.

According to the present invention, the charge level of the high-voltage battery is detected and the target charge current to the high-voltage battery is calculated so as to reach the target charge level.
The electric load current supplied from the low-voltage battery to the on-vehicle electric load is detected, and the target charging current and the electric load current are added to calculate a target generation current by the electric motor. By controlling the power generation of the motor, that is, by controlling the power generation in consideration of the electric load current supplied from the low-voltage battery to the on-vehicle electric load, the charging efficiency is improved and the capacity of the battery is fully utilized. Can be used for

According to the fifth aspect of the invention, the use of a lead-acid battery as the high-voltage battery makes it possible to significantly reduce the cost.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a system diagram of a hybrid vehicle showing one embodiment of the present invention.

An output side of an internal combustion engine (hereinafter referred to as an engine) 1 is directly connected to an electric motor (hereinafter referred to as a motor generator) 2 which also serves as a generator, and a transmission 3 is connected to the motor generator 2. Drive shaft 4 on the output side
Thus, the axle 6 on the driving wheel side is driven via the differential 5.

Here, the motor generator 2 is
Used as a starting means for cranking the engine 1 when the engine is started or when the vehicle starts, especially when an idle stop device for automatically stopping the engine 1 under predetermined idle stop conditions is provided, It is used when the engine 1 is automatically started under a predetermined idle stop release condition. On the other hand, if necessary, the torque of the motor 2 is added to the torque of the engine 1 under a predetermined operating condition such as acceleration. Used to smoothly accelerate the vehicle. Then, under predetermined operating conditions including at the time of deceleration operation, the motor generator 2 is used as a generator and used for charging a battery, and particularly at the time of deceleration operation, energy from the drive shaft 4 side is regenerated.
Power generation for battery charging is performed.

FIG. 2 is a system diagram of a power supply system in the hybrid vehicle. The high-voltage battery 11 is a chargeable / dischargeable battery power supply having a rating of about 42 V and serving as a power source of the motor generator 2. Specifically, a lead-acid battery (lead-acid battery) whose composition changes during charge / discharge A lead-acid battery using a lead grid containing lead as an electrode and dilute sulfuric acid as an electrolyte is used.

Here, when the high-voltage battery 11 is charged, that is, when the generated power is obtained from the motor generator 2, the three-phase AC power generated by the motor generator 2 is converted into DC power by the inverter 12. The electric power is supplied via the junction box 13, and at the time of discharging, the discharged electric power is converted into three-phase AC electric power via the junction box 13 and the inverter 12 and supplied to the motor generator 2.

The low-voltage battery 14 is a lead-acid battery having a rating of about 14 V which is generally used as a power source for an on-vehicle electric load including an engine auxiliary load, and its electric energy is supplied from the motor generator 2 to the inverter 12 and the junction. After passing through the box 13, it is stored via the DC / DC converter 15.

The control unit 16 receives various operating conditions of the vehicle including the engine speed Ne, the vehicle speed VSP, and the idle switch signal. The control unit 16 generates the current from the motor generator 2 via the current sensor and the voltage sensor. The converted generated current IMG, the charging current (or discharging current) IH to the high-voltage battery 11 and the terminal voltage VH thereof are detected. And based on these,
It has a function of controlling the operation of the motor generator 2, and particularly has a charge level SOC (State of State) of the high-voltage battery 11.
Charge), and has a function as power generation amount feedback control means for performing feedback control of the power generation amount (generation current) of the motor generator 2 so as to reach the target charge level TSOC. Note that detection of the charge level SOC is performed by estimation based on the IH and VH.

FIG. 3 is a control block diagram of the control of the power generation amount (generation current) of the motor generator 2 by the control unit 16, and the whole corresponds to a power generation amount feedback control means.

The target charge level switching means 21 sets the target charge level TSOC of the high-voltage battery 11, and has a margin for deceleration operation (during energy regeneration) during steady operation by a changeover switch (SW). , The target charge level TSOC is set to a lower predetermined value TSOCL,
During deceleration operation, the target charge level TSOC is set to a higher predetermined value TSOCH for sufficient energy regeneration.

Here, the target charge level TSOC is a ratio of the target charge amount to a full charge amount (a predetermined initial capacity or a full charge amount learned in a full charge state), and is a TS in a normal operation.
OCL is set to, for example, 80%, and TSOCH during deceleration operation is set to, for example, 95%.

More specifically, as shown in the flowchart of FIG. 4, at S1, the engine speed Ne, the vehicle speed VSP, and the idle switch signal are used to determine the deceleration operation (Ne ≧ predetermined value, VSP ≧ predetermined value, idle Switch ON) is determined. As a result, when the vehicle is not in the deceleration operation, that is, in the case of the steady operation, the process proceeds to S2, and the target charge level TSOC is lowered to a predetermined value TSOCL (for example, 80).
%). Further, in the case of the deceleration operation, the process proceeds to S3, in which the target charge level TSOC is increased to a predetermined value TSOC.
H (for example, 95%).

Although TSOCH during deceleration operation is set to be equivalent to the full charge level, considering the detection error (estimation error) of the actual charge level SOC, if the detection error is ± α (%), 100 -Set to α (%). Therefore, if the detection error is ± 5%, it is set to 95%. This is to prevent overcharging due to a detection error.

The charge level detecting means 22 detects (estimates) the actual charge level SOC of the high-voltage battery 11.
Specifically, first, at the time of startup (at the time of large discharge), the discharge characteristic VH = VH0−IH · R0 (VH is a battery terminal voltage,
VH0 is the open end voltage (electromotive force), IH is the discharge current, R0
Is the internal resistance), VH and I at a plurality of actually detected points
From H, VH0 and R0 are obtained, and the charge amount = f (VH0) is estimated. Thereafter, the charge / discharge current IH of the high-voltage battery 11 detected by the current sensor is integrated over time to update the charge amount (charge amount = charge amount + IH ・ Δt; Δt is a time interval of the integration). Then, the charge amount obtained in this manner is divided by a full charge amount (a predetermined initial capacity or a full charge amount learned in a full charge state) to obtain a charge level SOC (%).
Is calculated.

Here, the charge level SOC and the target charge level TSOC are detected and set as the ratio (%) to the fully charged state, but are detected and set as the charge amount which is the absolute amount (A · Hr). It may be.

The target charge current calculating means 23 compares the target charge level TSOC with the actual charge level SOC, and multiplies the difference (TSOC-SOC) by a gain K based on the proportional integral control to calculate the charge amount. The feedback control amount is calculated, and this is converted into a current to obtain a high-voltage battery 11.
Calculate the target charging current to

On the other hand, the generated current detecting means 24 detects the actual generated current IM of the motor generator 2 by the current sensor.
G is detected. The charging current detecting means 25 detects an actual charging current IH to the high-voltage battery 11 by a current sensor.

The electric load current detecting means 26 detects the high voltage battery 11 from the current IMG generated by the motor generator 2.
Is subtracted from the charging current IH to calculate the electric load current (= IMG-IH) supplied to the vehicle-mounted electric loads such as the air conditioner, the power steering, the light, and the wiper. That is, the charge current IH to the high-voltage battery 11 is subtracted from the current IMG generated by the motor generator 2 to obtain a charge current IL to the low-voltage battery 14 = IMG-IH. IL is expressed by the electric load current (=
IL).

Battery charge target power generation current calculation means 27
Is calculated by adding the electric load current calculated by the electric load current detecting means 26 to the target charging current calculated by the target charging current calculating means 23, and calculating the target generated current of the motor generator 2 (= target charging current + Electric load current) is calculated.

Target power generation current setting means 28 during battery discharge
Is for obtaining a small amount of generated current from the motor generator 2 during battery discharge in order to prevent battery deterioration during battery discharge, and sets the target generated current to about 1 to 2 A (constant).

The target power generation current determination means 29 determines the target power generation current at the time of battery charging, calculated by the battery power target power generation current calculation means 27, as a target power generation current by the selection switch (SW) during battery charging. And
During battery discharge, the target power generation current during battery discharge (trace power generation current) set by the target power generation current at battery discharge calculation means 28 is determined as the target power generation current.

The target torque calculating means 30 converts the target generated current determined by the target generated current determining means 29 into a target torque with reference to the table shown in FIG. The motor generator drive current control means 31 refers to the map shown in FIG. 3B based on the target torque and the engine speed Ne to determine the current engine speed Ne.
Motor generator 2 required to produce target torque
Is determined and output, and thereby the generated current of the motor generator 2 is controlled. Here, the target torque calculation means 30 and the motor generator drive current control means 31 correspond to the power generation amount control means.

With the above-described control, a lead-acid battery is used as the high-voltage battery 11, and the battery is charged so as to leave a margin during deceleration operation (at the time of energy regeneration) during steady-state operation. Energy regeneration becomes possible, and the regeneration efficiency can be greatly improved.
Further, it is possible to prevent the battery from being deteriorated due to overcharging and also prevent the deceleration G from becoming too large.

[Brief description of the drawings]

FIG. 1 is a system diagram of a hybrid vehicle showing an embodiment of the present invention.

FIG. 2 is a system diagram of a power supply system in the hybrid vehicle according to the first embodiment;

FIG. 3 is a control block diagram of power generation control of a motor generator.

FIG. 4 is a flowchart for switching a target charge level.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Engine 2 Motor generator 3 Transmission 11 High voltage battery 12 Inverter 13 Junction box 14 Low voltage battery 15 DC-DC converter 16 Control unit 21 Target charging level switching means 22 Charge level detecting means 23 Target charging current calculating means 24 Generated current detection Means 25 Charge current detecting means 26 Electric load current detecting means 27 Target generating current calculating means at battery charging 28 Target generating current setting means at battery discharging 29 Target generating current determining means 30 Target torque calculating means (power generation amount controlling means) 31 Motor generator Drive current control means (power generation amount control means)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G093 AA07 BA00 CB01 CB07 EB09 FA04 5H115 PA11 PG04 PI15 PI16 PI29 PI30 PO17 PU01 PU08 PU25 PV02 PV09 QE10 QI04 QN09 RB08 SE04 SE06 TI01 TI05 TI06 TO12 TR19 TU16

Claims (5)

[Claims] An internal combustion engine as a driving source for driving a vehicle,
An electric motor having a high-voltage battery as a power source, and under predetermined operating conditions including a time of deceleration operation, using the electric motor as a generator, the high-voltage battery and a low-voltage battery for a vehicle-mounted electric load. A control device for a hybrid vehicle that charges the electric motor, wherein a power generation amount feedback control unit that detects a charge level of the high-voltage battery and performs feedback control of a power generation amount of the electric motor so as to reach a target charge level; A control device for a hybrid vehicle, comprising target charge level switching means for making a target charge level different between during operation and during deceleration operation. 2. The hybrid vehicle control device according to claim 1, wherein a target charge level during steady operation is set lower than a target charge level during deceleration operation. 3. The hybrid vehicle control device according to claim 2, wherein the target charge level at the time of deceleration operation is set to correspond to a full charge level. 4. The power generation amount feedback control means includes: a charge level detection means for detecting a charge level of the high-voltage battery; and a target charge current to the high-voltage battery by comparing an actual charge level with a target charge level. A target charging current calculating unit that calculates an electric load current supplied to the vehicle-mounted electric load from the low-voltage battery, and adding the target charging current and the electric load current. A target power generation current calculation means for calculating a target power generation current by the electric motor, and a power generation amount control means for controlling the power generation amount of the electric motor to obtain the target power generation current, Claim 1 to
The control device for a hybrid vehicle according to claim 3. 5. The control device for a hybrid vehicle according to claim 1, wherein a lead-acid battery is used as the high-voltage battery.