JP2004112997A - Control device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine and a motor generator using a high-voltage battery as a power source, and to overcharge and charge a high-voltage battery and a low-voltage battery for a vehicle-mounted electric load by the motor generator during deceleration operation. Prevent over-deceleration and efficiently recover the amount of regeneration.
SOLUTION: A target charging current is calculated according to a state of charge of a high-voltage battery by a target charging current calculating unit, and the target charging current is regulated by a first limiter unit having a constant limiter value. The electric load current detecting means 27 detects the electric load current to the electric load on the vehicle. The target generation current calculation means 28, 30 adds the target charging current and the electric load current to calculate a target generation current by the motor generator 2, and sets a limiter according to ON / OFF of an on-vehicle electric load (for example, an air conditioner). It is regulated by the second limiter 31 having a value.
[Selection diagram] FIG.

Description

The present invention includes an internal combustion engine and an electric motor that uses a high-voltage battery as a power source as a drive source for running the vehicle. During deceleration operation, the electric motor is used as a generator, and the high-voltage battery is mounted on the vehicle. The present invention relates to a control device for a hybrid vehicle that charges a low-voltage battery for an electric load.

In recent years, as shown in Patent Literature 1, development of a hybrid vehicle including an internal combustion engine (gasoline engine) and an electric motor using a high-voltage battery as a power source has been advanced as a driving source for the vehicle. .

In such a hybrid vehicle, during deceleration operation, 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.

Here, the control of the generated current by the electric motor calculates a target charging current to the high-voltage battery in accordance with a state of charge of the high-voltage battery, and detects an electric load current supplied to the on-vehicle electric load, By adding these, a target generated current by the electric motor is calculated, and the calculation is performed based on this.

JP-A-10-304511

However, if the generated current becomes too large during energy regeneration during deceleration operation, the high-voltage battery will be in an overcharged state, leading to faster battery deterioration or too large deceleration (deceleration G). There is a problem that the driver feels strange.

Therefore, it is conceivable to set a limiter for the control value of the generated current (target generated current). However, since the overcharge and the deceleration G differ depending on the conditions, in order to obtain the regenerative amount efficiently, set the limiter appropriately. There is a need to.

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 susceptible to deterioration due to overcharging. It is essential to take countermeasures for prevention.

In view of such circumstances, the present invention prevents battery deterioration due to overcharging by charging the battery as much as it can be charged, and also prevents the deceleration G from becoming too large, and reduces the amount of regeneration. The aim is to be able to take well.

For this reason, in the invention according to claim 1, a limiter is provided for a control value (target generated current) of the generated current by the electric motor during the deceleration operation, and the limiter value is set according to ON / OFF of the on-vehicle electric load. It is characterized by being variable.

The invention according to claim 2 is characterized in that the limiter value of the limiter means is variable according to the engine speed.

In the invention according to claim 3, target charging current calculating means for calculating a target charging current for the high-voltage battery in accordance with the state of charge of the high-voltage battery, and electric power for detecting an electric load current supplied to the vehicle-mounted electric load. Load current detection means, and target generation current calculation means for calculating a target generation current by the electric motor by adding the target charging current and the electric load current, and the limiter means for the target generation current. On the other hand, another limiter means is provided for the target charging current.

In the invention according to claim 4, the another limiter has a constant limiter value.

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

According to the first aspect of the present invention, the control value (target generated current) of the generated current by the electric motor at the time of deceleration operation is provided with limiter means, so that the battery can be charged as much as possible, thereby overcharging. By preventing battery deterioration due to charging and also preventing the deceleration G from becoming too large, the limiter value is made variable according to ON / OFF of the vehicle-mounted electric load, thereby enabling the vehicle-mounted electric load of an air conditioner or the like to be changed. When turned off, the amount of regeneration can be efficiently obtained.

According to the invention according to claim 2, the limiter value of the limiter means is made variable in accordance with the engine speed, so that the limiter value is set smaller on the low speed side and larger on the high speed side in accordance with the engine speed. Since the amount of torque that can be absorbed by the motor based on the current engine speed is used as the limiter value of the motor generated current, the amount of regeneration can be efficiently obtained.

According to the third aspect of the present invention, the target charging current to the high-voltage battery is calculated according to the state of charge of the high-voltage battery, the electric load current supplied to the vehicle-mounted electric load is detected, and these are added. When calculating the target generated current by the electric motor, the limiter is provided for the target generated current, and another limiter is provided for the target charging current, so that more appropriate setting is provided. Becomes possible.

According to the invention according to claim 4, the separate limiter means can be easily implemented by having a constant limiter value as a chargeable allowable value based on the characteristic values of overcharge and deceleration G.

According to the invention according to claim 5, the cost is reduced by using a lead-acid battery as the high-voltage battery.

Hereinafter, embodiments of the present invention will be described.
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 also serving as a generator, and a transmission 3 is connected to the motor generator 2. The drive shaft 4 drives the axle 6 on the drive wheel side via the differential 5.

Here, the motor generator 2 is used as a starting unit that performs cranking of the engine 1 when the engine is started or the vehicle starts, and in particular, an idle stop device that automatically stops the engine 1 under a predetermined idle stop condition. When equipped, it is used to automatically start the engine 1 under predetermined idle stop release conditions after idle stop, and if necessary, to reduce the torque of the engine 1 under predetermined operating conditions such as acceleration. It is used to smoothly accelerate the vehicle by adding the torque of No. 2. During the deceleration operation, the generator regenerates energy from the drive shaft 4 side to generate power and use it for charging a battery.

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 source having a rating of about 42 V and serving as a power source of the motor generator 2, specifically, a lead-acid battery (oxidation 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, in a state where 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 and is connected to the junction. The power is supplied via the box 13, and at the time of discharging, the discharged power is converted into three-phase AC 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 that 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 box 13. After passing through, 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 ON / OFF of the air conditioner, and the gear ratio. In addition, the actual charge amount (charge level) SOC of the high-voltage battery 11 (State of Charge). , The generated current IMG generated by the motor generator 2 and converted by the inverter 12, the detection of the charging current I42 to the high-voltage battery 11, and the like, and the operation of the motor generator 2 is controlled based on these. Has a function.

FIG. 3 is a control block diagram of the control of the generated current of the motor generator 2 by the control unit 16.

The target charge amount setting means 21 sets a target charge amount TSOC of the high-voltage battery 11. Here, the target charge amount TSOC is set to, for example, 90% as a percentage of the full charge state.

(4) The charge amount detection means 22 detects the actual charge amount SOC of the high-voltage battery 11. Specifically, the charge / discharge current of the high-voltage battery 11 detected by the current sensor is calculated by integrating the time, or the internal resistance is estimated from the change rate of the charge / discharge current, and is calculated based on the internal resistance. The charge amount SOC may be obtained as a ratio (%) to the fully charged state, or may be obtained as an absolute amount (A · Hr).

The target charge current calculation means 23 compares the target charge amount TSOC with the actual charge amount SOC, and multiplies the difference (TSOC-SOC) by a gain based on the proportional integral control to obtain a feedback control amount of the charge amount. Then, the target charge current to the high-voltage battery 11 is calculated.

In addition, in addition to performing feedback control to obtain the target charge amount of the high-voltage battery 11, feedback control may be performed to obtain the target voltage of the high-voltage battery 11. That is, while setting the target voltage (for example, 44 V) of the high-voltage battery 11, the actual voltage is detected, and the feedback control amount of the voltage is calculated based on the comparison result between the target voltage and the actual voltage. The conversion may be performed to calculate a target charging current to the high-voltage battery 11.

The first limiter unit 24 compares the target charging current calculated by the target charging current calculating unit 23 with a predetermined limiter value (a constant value, for example, 50 A), and when the target charging current is equal to or larger than the limiter value. The target charging current is regulated to a limiter value.

4. Specifically, as shown in the flowchart of FIG. 4, the limiter value LT1 is read, and it is determined whether or not the target charging current ≧ LT1, and if the target charging current ≧ LT1, the target charging current is changed to LT1. Here, the limiter value LT1 is a value determined as a chargeable allowable value from characteristic values of overcharge and deceleration G.

On the other hand, the generated current detection means 25 detects the actual generated current IMG of the motor generator 2 by the current sensor.

The charging current detecting means 26 detects the actual charging current I42 to the high-voltage battery 11 by the current sensor.

The electric load current detecting means (estimating means) 27 subtracts the charging current I42 to the high-voltage battery 11 from the generated current IMG of the motor generator 2, and outputs the electric load current (= IMG- I42) is calculated. That is, the charging current I42 to the high-voltage battery 11 is subtracted from the generation current IMG of the motor generator 2 to obtain a charging current I14 to the low-voltage battery 14 = IMG-I42. I14 is estimated as an electric load current (= I14).

The battery charge target generated current calculating means 28 calculates the target charging current calculated by the target charging current calculating means 23 and passed through the first limiter means 24 by the electric load current detecting means (estimating means) 27. The electric load current is added to calculate a target generated current of the motor generator 2 (= target charging current + electric load current).

The battery discharge target power generation current setting means 29 is for obtaining a small power generation current from the motor generator 2 at the time of battery discharge in order to prevent battery deterioration at the time of battery discharge. ).

The target power generation current determination means 30 determines the target power generation current at the time of battery charging calculated by the battery power target power generation current calculation means 28 as a target power generation current by the selection switch (SW) during battery charging. During discharging, the target power generation current during battery discharge (trace power generation current) set by the target power generation current calculation means 29 during battery discharge is determined as the target power generation current.

The second limiter 31 compares the target power generation current determined by the target power generation current determination means 30 with a limiter value determined in accordance with the operating conditions. If the target power generation current is equal to or greater than the limiter value, the target power generation current is determined. Limit to the limiter value.

Specifically, as shown in the flowchart of FIG. 5, a limiter value LT2 is calculated based on ON / OFF of an on-vehicle electric load (for example, an air conditioner), and it is determined whether or not target power generation current ≧ LT2. When current ≧ LT2, the target power generation current is changed to LT2.

Specifically, as shown in FIG. 6, the limiter value LT2 is set to be large when the air conditioner is OFF and small when the air conditioner is ON, as shown in FIG. . This is to increase the regeneration amount when the air conditioner is off. The setting may be made in accordance with ON / OFF of an on-vehicle electric load (for example, power steering, light, etc.) other than the air conditioner.

Alternatively, as shown in FIG. 7, the limiter value LT2 is set to be large when the air conditioner is turned off and small when the air conditioner is turned on in accordance with ON / OFF of the air conditioner, and is corrected in accordance with the engine speed Ne. It is small on the low rotation side and large on the high rotation side. This is because the amount of torque that can be absorbed by the motor generator 2 from the current engine speed Ne is used as the limit value of the motor generated current.

The target torque calculating means 32 converts the target generated current determined by the target generated current determining means 30 and passed through the second limiter 31 into a target torque with reference to the table in FIG.

The motor generator control means (current command means) 33 refers to the map shown in FIG. 3B based on the target torque and the engine speed Ne, and sends a signal to the motor generator 2 required to output the target torque. The current command value is determined, and the generated current of the motor generator 2 is controlled based on the determined current command value.

According to the above control, a lead-acid battery is used as the high-voltage battery 11 and the battery is charged by an amount that can be charged, thereby preventing battery deterioration due to overcharge and preventing the deceleration G from becoming too large. At the same time, the amount of regeneration can be efficiently obtained.

ハ イ ブ リ ッ ド System diagram of hybrid vehicle showing one embodiment of the present invention シ ス テ ム System diagram of power supply system in hybrid vehicle 制 御 Control block diagram of generated current control of motor generator フ ロ ー チ ャ ー ト Flowchart of the first limiter フ ロ ー チ ャ ー ト Flowchart of the second limiter 図 Diagram showing limiter value setting example (1) of second limiter means 図 Diagram showing a limiter value setting example (2) of the second limiter means

Explanation of reference numerals

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 amount setting means 22 Charge amount detecting means 23 Target charging current calculating means 24 First limiter Means 25 Generated current detecting means 26 Charging current detecting means 27 Electric load current detecting means (estimating means)
28 Battery Generated Target Generated Current Calculation Means 29 Battery Discharge Target Generated Current Setting Means 30 Target Generated Current Determination Means 31 Second Limiter Means 32 Target Torque Calculation Means 33 Motor Generator Control Means (Current Command Means)

Claims (5)

A drive source for driving the vehicle includes an internal combustion engine, and an electric motor using a high-voltage battery as a power source.During deceleration operation, the electric motor is used as a generator, and the high-voltage battery and a vehicle-mounted electric load are used. In a control device for a hybrid vehicle that charges a low-voltage battery,
A control device for a hybrid vehicle, wherein a limiter is provided for a control value of a current generated by the electric motor during a deceleration operation, and the limiter value is made variable according to ON / OFF of an on-vehicle electric load. The control device for a hybrid vehicle according to claim 1, wherein the limiter value of the limiter means is made variable in accordance with the engine speed. Target charge current calculation means for calculating a target charge current to the high-voltage battery according to the state of charge of the high-voltage battery, and an electric load current detection means for detecting an electric load current supplied to the vehicle-mounted electric load, A target generation current calculation unit that calculates a target generation current by the electric motor by adding the target charging current and the electric load current,
The control device for a hybrid vehicle according to claim 1, wherein the limiter is provided for the target generated current, and another limiter is provided for the target charging current. 4. The control device for a hybrid vehicle according to claim 3, wherein the another limiter has a constant limiter value. The control device for a hybrid vehicle according to any one of claims 1 to 4, wherein a lead-acid battery is used as the high-voltage battery.

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