JP2016112932A - Power source protection device for hybrid vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power source protection device of a hybrid vehicle capable of preventing over-charging of a battery, to avoid a state in which a battery assembly must be replaced.SOLUTION: When SOC of a battery reaches an over-charge prevention threshold value S3 which is higher than an upper limit value S1 in a normal usable range but lower than a charge tolerable limit value S2, a driving force on a positive side is generated by a motor for discharging of the battery, and a driving force on a negative side is generated by an engine to absorb the driving force on the positive side generated by the motor.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a power supply control device for a hybrid vehicle, and more particularly to a technique for preventing overcharging of a battery.

  2. Description of the Related Art In recent years, from the viewpoint of environmental protection, a hybrid electric vehicle (hereinafter referred to as a hybrid vehicle) that uses an engine and a traveling motor (electric motor) as a vehicle drive source is known as an environment-friendly vehicle. In such a hybrid vehicle, the battery can be charged by performing a regenerative operation in which the motor is used as a generator during traveling downhill (see Patent Document 1).

JP 2012-131292 A

  However, for example, if there is a problem that the setting of the zero torque of the motor is offset to the charging side, charging is performed even though the required torque for the motor is zero. The same applies to the case where there is a problem with the control unit that controls the motor, and the required torque for the motor is always on the charging side. Or, there may be a case where the required torque to the motor becomes the charging side due to a communication abnormality such as CAN connected to the control unit or sensor, and the battery is continuously charged. Further, a problem may occur in the inverter between the battery and the motor, and the required torque for the motor may always be on the charging side.

  When the battery is overcharged due to such a malfunction of the hybrid system, the battery control unit forcibly opens the contactor incorporated in the electric circuit of the battery in order to prevent ignition of the battery. However, when the contactor is opened, the battery can no longer be used and the battery assembly must be replaced.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a hybrid vehicle capable of preventing overcharging of a battery and avoiding a situation where a battery assembly must be replaced. It is to provide a power protection device.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

  A power source protection device for a hybrid vehicle according to this application example includes an engine that is a drive source of the vehicle, an electric motor that is the drive source of the vehicle and can generate power, supply of electric power for driving the electric motor, and the electric motor A battery capable of storing the generated electric power, a charge amount detection means for detecting the charge amount of the battery, and a charge amount of the battery detected by the charge amount detection means is set in a preset normal usable range. When the limit threshold value higher than the upper limit value is reached, the safety means for cutting off the electric circuit of the battery and the charge amount of the battery detected by the charge amount detection means are higher than the upper limit value of the normal usable range. When a predetermined threshold value that is higher and lower than the limit threshold value is reached, a positive driving force is generated by the motor to discharge the battery, and the engine Ri and cause negative side of the driving force and a power protection control means for absorbing the positive side of the driving force by the motor.

  According to the present invention using the above means, it is possible to prevent the battery from being overcharged and avoid the situation where the battery assembly has to be replaced.

1 is a schematic configuration diagram of a power supply protection device for a hybrid vehicle according to an embodiment of the present invention. It is a time chart showing an example of change of various parameters at the time of performing power supply protection control.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a power source protection device for a hybrid vehicle according to an embodiment of the present invention, which will be described with reference to FIG.

  The hybrid vehicle 1 is configured as a so-called parallel hybrid truck, and is simply referred to as a vehicle in the following description.

  A vehicle 1 is equipped with a diesel engine (hereinafter referred to as an engine) 2 as a driving power source and a motor 3 that can also operate as a generator such as a permanent magnet synchronous motor. A clutch 4 is connected to the output shaft of the engine 2, and an input side of the transmission 5 is connected to the clutch 4 via a rotating shaft of the motor 3. A differential device 7 is connected to the output side of the transmission 5 via a propeller shaft 6, and left and right drive wheels 9 are connected to the differential device 7 via a drive shaft 8.

  The transmission 5 is based on a general manual transmission and automates the engagement / disengagement operation of the clutch 4 and the switching operation of the shift stage. In this embodiment, the transmission 5 has six forward speeds and one reverse speed. ing. Of course, the configuration of the transmission 5 is not limited to this, and can be arbitrarily changed. For example, the transmission 5 may be embodied as a manual transmission, or a so-called dual clutch automatic transmission having two power transmission systems. It may be embodied as a machine.

  A battery 11 is connected to the motor 3 via an inverter 10. The DC power stored in the battery 11 is converted into AC power by the inverter 10 and supplied to the motor 3, and the driving force generated by the motor 3 is transmitted to the driving wheels 9 after being shifted by the transmission 5. Run (this is called power running). For example, when the vehicle 1 decelerates or travels on a downhill road, the motor 3 operates as a generator by reverse driving from the drive wheel 9 side. The negative driving force generated by the motor 3 is transmitted to the driving wheel 9 side as a braking force, and the AC power generated by the motor 3 is converted into DC power by the inverter 10 and charged to the battery 11 (this is This is called regenerative operation).

  In addition, the motor 3 can be rotated by the driving force generated by the engine 2 to generate power, and the battery 11 can be actively charged (this is called engine power generation). Conversely, the battery 3 can be forcibly discharged by causing the motor 3 to generate a positive driving force while absorbing the excess positive driving force with the negative driving force of the engine 2. It is possible (this is called forced discharge). The negative driving force of the engine 2 is generated by an auxiliary brake such as a retarder or a compression release brake, in addition to an engine brake caused by the friction of the engine 2, for example.

  The driving force generated by the motor 3 is transmitted to the driving wheel 9 regardless of the state of connection / disconnection of the clutch 4, and the driving force generated by the engine 2 is driven only when the clutch 4 is connected. 9 side. Therefore, when the clutch 4 is disengaged, the positive or negative driving force generated by the motor 3 as described above is transmitted to the driving wheel 9 side, and the vehicle 1 travels. When the clutch 4 is connected, the driving force of the engine 2 and the motor 3 is transmitted to the driving wheel 9 side, or only the driving force of the engine 2 is transmitted to the driving wheel side by setting the driving force of the motor 3 to zero. Or the vehicle 1 travels.

  The vehicle 1 is equipped with a vehicle ECU 20 that is a control circuit for integrated control of the entire vehicle. Although not shown, the vehicle ECU 20 is connected to an actuator for connecting / disconnecting the clutch 4, an actuator for shifting the transmission 5, and the like, and an engine ECU 21 for engine control, a motor ECU 22 for motor control, and a battery 11 is connected. In addition, although not shown, various sensors such as an accelerator sensor that detects an accelerator operation amount are connected to the vehicle ECU 20.

  And vehicle ECU20 acquires information from various ECUs and various sensors. For example, the vehicle ECU 20 acquires information such as the engine speed from the engine ECU 21, the motor speed from the motor ECU 22, and SOC (State Of Charge) of the battery 11 from the battery ECU 23.

  The vehicle ECU 20 calculates a required torque required for the vehicle 1 to travel based on the accelerator operation amount by the driver, and the vehicle 1 based on the required torque and the SOC (State Of Charge) of the battery 11. Select the driving mode. In the present embodiment, there are an engine travel mode, a motor travel mode, a hybrid travel mode, an engine power generation mode, and a forced discharge travel mode as travel modes.

  The engine travel mode is a travel mode in which, for example, when the SOC value of the battery 11 is at the lower limit and the motor 3 cannot be used, the motor travel mode travels using only the driving force of the engine 2. This is a travel mode in which the travel is performed. The hybrid travel mode is a travel mode in which travel is performed using both the driving force of the engine 2 and the motor 3. The engine power generation travel mode is a travel mode in which power is generated by rotating the motor 3 using the driving force of the engine 2 while traveling using the driving force of the engine 2. The forced discharge traveling mode is a traveling mode in which the battery 11 is forcibly discharged by generating a negative driving force in the engine 2 while traveling using the driving force of the motor 3. The vehicle ECU 20 selects one of these travel modes, and controls the engine 2 via the engine ECU 21 and the motor 3 via the motor ECU 22 according to the selected travel mode.

  Specifically, the vehicle ECU 20 converts the required torque into a torque command value that the engine 2 and the motor 3 should output based on the selected travel mode. For example, in the hybrid travel mode, the required torque is distributed to the engine 2 side and the motor 3 side, and torque command values for the engine 2 and the motor 3 are calculated based on the gear position at that time. In the engine travel mode, the required torque is converted into a torque command value for the engine 2 based on the gear position, and in the motor travel mode, the required torque is converted into a torque command value for the motor 3 based on the gear speed. Further, in the engine power generation travel mode, a value obtained by combining the required torque and the torque required for power generation by the motor 3 is calculated as a torque command value for the engine 2. In the forced discharge travel mode, the positive driving force is calculated as a torque command for the motor 3, and the negative driving force is calculated as a torque command value for the engine 2 to absorb the surplus positive driving force. At this time, the surplus positive driving force of the motor 3 is set within a range that can be absorbed by the engine 2 as a negative driving force.

  Then, the vehicle ECU 20 disconnects the clutch 4 in the motor travel mode to execute the selected travel mode, and connects the clutch 4 in the engine travel mode, the hybrid travel mode, the engine power generation travel mode, and the forced discharge travel mode. Thus, torque command values are appropriately output to the engine ECU 21 and the motor ECU 22. Further, during traveling of the vehicle 1, the vehicle ECU 20 calculates a target shift stage from a shift map (not shown) based on the accelerator operation amount, the vehicle speed, and the like, and the actuator 4 connects and disconnects the clutch 4 to achieve this target shift stage. A gear change operation is executed.

  On the other hand, the engine ECU 21 executes injection amount control and injection timing control so as to achieve a torque command value based on the travel mode selected by the vehicle ECU 20. For example, in the engine travel mode, the hybrid travel mode, and the engine power generation travel mode, a driving force is generated in the engine 2 with respect to the positive torque command value, and an engine brake or the like is generated with respect to the negative torque command value. In the case of the motor travel mode, the engine 2 is stopped or held by stopping the fuel injection or is set in an idle operation state.

  Further, the motor ECU 22 drives and controls the motor 3 via the inverter 10 so as to achieve a torque command value based on the travel mode selected in the vehicle ECU 20. For example, in the motor travel mode, the hybrid travel mode, and the forced discharge travel mode, the motor 3 is subjected to power running control with respect to the positive torque command value to generate the positive drive force. On the other hand, in the motor travel mode and the hybrid travel mode, the motor 3 is regeneratively controlled to generate a negative drive force with respect to the negative torque command value. In the case of the engine running mode, the driving force of the motor 3 is controlled to zero. Further, in the case of the engine power generation travel mode, power is generated by receiving the driving force of the engine 2.

  Further, the battery ECU 23 detects the temperature of the battery 11, the voltage of the battery 11, the current flowing between the inverter 10 and the battery 11, etc., calculates the SOC of the battery 11 from these detection results, and detects this SOC. It outputs to vehicle ECU20 with a result (charge amount detection means).

  For the battery 11, a normally usable SOC range (hereinafter referred to as a normal usable range) is predetermined. Further, since there is a risk of ignition or the like when overcharged, the battery 11 includes a safety device 12 (safety means) that prevents the contactor built in the electric circuit of the battery 11 from being disconnected (opened) to be charged / discharged. ) Is attached. The battery ECU 23 monitors the SOC of the battery 11, and when the charge allowable limit value S <b> 2 (limit threshold value) set to a value higher than the upper limit value S <b> 1 of the normal usable range is exceeded, the safety device 12 causes the battery 11. Shut off the electrical circuit.

  The vehicle ECU 20 performs power source protection control for preventing overcharging before the SOC of the battery 11 exceeds the allowable charging limit value. Specifically, the vehicle ECU 20 sets an overcharge prevention threshold value S3 that is higher than the upper limit value S1 of the normal usable range and lower than the allowable charge limit value S2, and when the SOC reaches the overcharge prevention threshold value S3. By switching to the forced discharge travel mode, the SOC of the battery 11 is consumed. The vehicle ECU 20 is connected with a warning lamp 13 used for power supply protection control. For example, the vehicle ECU 20 switches to the forced discharge travel mode, and at the same time turns on the warning lamp 13 to notify the driver of the abnormality and prompts the vehicle 1 to perform maintenance and inspection.

  Here, referring to FIG. 2, FIG. 2 shows a time chart showing an example of the transition of various parameters when the power protection control is executed, and the operation and effect of the present embodiment will be described below based on FIG. Will be described.

  At the time of starting the time chart of FIG. 2, for example, the vehicle 1 is on a downhill road and the torque command value (hereinafter referred to as “motor torque”) to the motor 3 is on the negative side, that is, regenerative operation is performed. For this reason, the SOC of the battery 11 gradually increases. At this time, the clutch 4 is in a disconnected state, and a torque command value (hereinafter referred to as engine torque) to the engine 2 is zero.

  At time t1 in FIG. 2, the SOC of the battery 11 exceeds the upper limit value S1 of the normal usable range, and the battery is not charged any more, so the vehicle ECU 20 switches the operation mode from the motor travel mode to the engine travel mode. Therefore, from time t1, the vehicle ECU 20 sets the motor torque to 0 and causes engine braking with respect to the negative required torque.

  Still, when the SOC increases due to a malfunction or the like on the hybrid system and the SOC reaches the overcharge prevention threshold S3 at time t2, the vehicle ECU 20 switches the operation mode to the forced discharge travel mode. Specifically, the vehicle ECU 20 generates a positive driving force as motor torque, while the engine 2 generates a negative driving force that absorbs the motor torque. That is, the engine load is increased by using the engine brake and the retarder, and the motor torque is increased accordingly. In addition, the vehicle ECU 20 lights the warning lamp 13 in the forced discharge travel mode to urge the driver to perform inspection or maintenance.

  Thus, when the motor 3 generates the positive driving force, the battery 11 is discharged and the SOC is consumed.

  When the SOC decreases to the upper limit value S1 of the normal usable range as at time t3 in FIG. 2, the vehicle ECU 20 returns the operation mode to the engine travel mode. Specifically, in the case of the downhill, the vehicle ECU 20 sets the motor torque to 0 and satisfies the negative required torque by engine braking. Although not shown here, if the vehicle is traveling on a flat road or an uphill, the motor torque is set larger than 0, the battery is discharged in the hybrid travel mode or the motor travel mode as usual, and the SOC is consumed. Good.

  Further, when the SOC rises again and reaches the overcharge prevention threshold value S3 as at time t4 in FIG. 2, the vehicle ECU 20 switches to the forced discharge travel mode again.

  As described above, when the SOC of the battery 11 reaches the overcharge prevention threshold S <b> 3, the vehicle ECU 20 switches to the forced discharge travel mode and uses the motor 3 to discharge the battery 11. Therefore, even when the zero torque of the motor 3 is offset to the charging side, or when the instruction to the motor 3 is always on the charging side due to the required torque for the motor 3, the torque command value from the motor ECU to the motor, communication abnormality, etc. By performing the forced discharge in response to the SOC reaching the overcharge prevention threshold S3, the actual SOC does not rise to the charge allowable limit value S2. That is, the use of the safety device 12 can be avoided.

  As described above, according to the power supply protection device for a hybrid vehicle in the present embodiment, it is possible to prevent the battery 11 from being overcharged and to avoid a situation where the battery assembly must be replaced by using the safety device 12.

  Although the description of the embodiment of the power supply protection device for a hybrid vehicle according to the present invention has been completed above, the embodiment is not limited to the above embodiment.

  In the above embodiment, when the forced discharge travel mode is executed, the warning lamp 13 is turned on to notify the driver of the abnormality, but means for warning the driver is not limited to this, for example, A warning may be given by displaying characters or by voice.

1 Vehicle 2 Engine 3 Motor (electric motor)
4 Clutch 5 Transmission 10 Inverter 11 Battery 12 Safety device (safety means)
13 Warning light 20 Vehicle ECU (power protection control means)
21 Engine ECU
22 Motor ECU
23 battery ECU (charge amount detection means)

Claims (1)

An engine that is a driving source of the vehicle;
An electric motor that is a drive source of the vehicle and can generate power;
A battery capable of supplying electric power for driving the electric motor and storing electric power generated by the electric motor;
Charge amount detecting means for detecting the charge amount of the battery;
Safety means for cutting off the electric circuit of the battery when the charge amount of the battery detected by the charge amount detection means reaches a limit threshold value higher than a preset upper limit value of the normal usable range;
When the charge amount of the battery detected by the charge amount detection means reaches a predetermined threshold value that is higher than the upper limit value of the normal usable range and lower than the limit threshold value, a positive driving force is generated by the electric motor. A power source protection control means for discharging the battery and generating a negative driving force by the engine to absorb a positive driving force by the electric motor;
A power protection device for a hybrid vehicle comprising:

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