JP2007015485A - Hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent uncomfortable feeling of a driver by suppressing the fluctuation of driving force in a vehicle due to excessive power even when the excessive power is generated. <P>SOLUTION: When a gear is shifted to a low gear ratio in a transmission 13, a controller 1 allows a first motor generator 11 to be operated for power generation so as to reduce the rotation speed of an engine 10 and allows a second motor generator 12 to be operated for power running with the use of the generated power. In this case, the controller 1 determines the generation of the excessive power by comparing the generated power of the first motor generator 11 with the requested power of the second motor generator 12. When it is determined that the excessive power is to be generated, efficiency is reduced in at least one of the first and second motor generators 11, 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hybrid vehicle of a vehicle, and more particularly to control at the time of shifting.

  In order to improve the output of a motor generator (hereinafter referred to as “MG”) in a hybrid vehicle, a technique of increasing the system voltage is effective. However, in general, the system voltage is determined by the voltage of the battery that supplies power to the MG, and the output of the MG usually depends on the voltage of the battery, and the improvement in output is limited.

On the other hand, in Japanese Patent Laid-Open No. 10-191503, by adjusting the relationship between the generated power and the consumed power by operating one MG with power generation while the battery is disconnected from the system and powering the other MG. A technique for increasing the system voltage and improving the output of the motor is disclosed.
JP-A-10-191503

  However, in the above prior art, when excessive power is generated, it cannot be stored in the battery and is supplied to the other MG as it is. For this reason, the output of the other MG increases more than necessary, and the driving force of the vehicle increases beyond the required driving force, which may make the driver feel uncomfortable.

  The present invention solves such a technical problem of the prior art, and suppresses fluctuations in the driving force of the vehicle due to excess power even when excessive power is generated, so that the driver does not feel uncomfortable. The purpose is to do.

  When shifting the transmission to a smaller gear ratio, the first motor generator is caused to generate electricity, thereby reducing the rotational speed of the engine, and the second motor generator is caused to perform a power running operation using the generated power. At this time, generation of excess power is determined by comparing the generated power of the first motor generator and the required power of the second motor generator, and if it is determined that excess power is generated, the first and second The efficiency of at least one of the motor generators is reduced.

  If excess power is generated during gear shifting, the efficiency of the first or second motor generator is reduced, and the excess power is absorbed by the heat generated by the first or second motor generator. Since excess electric power is not reflected in the driving force, it is possible to avoid generating a driving force that exceeds the required driving force and causing the driver to feel uncomfortable.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a system configuration diagram of a hybrid vehicle according to the present invention. The engine 10 is a prime mover such as an internal combustion engine and generates driving force. Motor generators (hereinafter referred to as “MG”) 11 and 12 are electric motors such as a three-phase AC rotating electric machine, and can generate power and run. Inverters 21 and 22 as control devices are connected to the MGs 11 and 12, respectively, and the inverters 21 and 22 are connected by a DC line 25 (power supply line).

  The transmission 13 is a stepped transmission having a plurality of shift stages, and includes a planetary gear mechanism, a clutch, a brake, a hydraulic circuit, and the like. The rotational speed and driving force of the engine 10 and the MG 11 are changed to the rotational speed and driving force according to the traveling state by changing the gear position of the transmission 13 and transmitted to the drive shaft 14 and the drive wheels 15. . In the drive shaft 14, the driving force of the MG 12 is applied by the MG 12 connected midway.

A battery 23 is connected to the middle of the DC line 25 via a switch 24, and the battery 23 supplies power to and receives charges from the MGs 11 and 12. If the switch 24 is opened, the connection between the DC line 25 and the battery output terminal 26 is cut off, and the battery 23 can be disconnected from the system. The voltage (system voltage) V _DC of the DC line 25 when the battery 23 is disconnected is determined from the relationship between the power generated by the MG 11 and the power consumed by the MG 12. That is, in this system, if the battery 23 is disconnected from the system, the system voltage _VDC can be arbitrarily controlled by the power generation control of the MG 11 and the driving force control of the MG 12.

  As described above, since the transmission 13 is a stepped transmission, it is necessary to reduce the rotational speed of the engine 10 at the time of upshift when the gear position is changed to the high speed side (low gear ratio side). Means for reducing the rotational speed of the engine 10 include utilization of the negative torque of the engine 10 itself and control of the clutch engaging force of the transmission 13. In this system, the engine 10 is operated by causing the MG 11 to generate electricity. Reduce the rotation speed.

  Since the target rotational speed of the engine 10 after the upshift is uniquely determined from the gear ratio (transmission ratio) of the transmission ratio 13, the rotational speed of the MG 11 is controlled so that the rotational speed of the engine 10 becomes the target rotational speed at the time of shifting. To do. Unlike an engine or a clutch, an electric motor has high speed control accuracy. Therefore, the rotation speed of the MG 11 can easily lead the rotation speed of the engine 10 to a target value.

  At this time, if the battery 23 is connected to the system, the torque of the MG 11 is limited by the voltage of the battery 23. In general, an electric motor, in particular, a synchronous machine using a permanent magnet, can increase the output as the inverter terminal voltage is higher. However, in a system connected to a battery, it is difficult to increase the system voltage beyond the battery voltage.

Therefore, in the present system, when the voltage V _DC of the DC line 25 exceeds the voltage V _{Batt of the} battery 23 at the time of shifting, the switch 24 is opened and the battery 23 is disconnected from the DC line 25. When the battery 23 is disconnected, the inverter 21 and the inverter 22 become only capacitors, so if the power generated by the MG 11 becomes larger than the power consumed by the MG 12, the charge at the capacitor end increases and the voltage of the DC line 25 increases. . As a result, the generated power of MG 11 can be increased without being restricted by the voltage V _Batt of battery 23, and the rotational speed of engine 10 can be quickly brought close to the target value.

  By the way, when priority is given to shortening the shift time, the generated power of the MG 11 exceeds the required power of the MG 12 obtained from the required driving force and the target gear ratio, and surplus power (hereinafter referred to as “excess power”) may be generated. is there. If the battery 23 is disconnected when this excess power is generated, the battery 23 cannot absorb the excess power, and the excess power is supplied to the MG 12 as it is. As a result, the driving force of the MG 12 increases and the driving force of the vehicle becomes larger than the required driving force, which may give the driver a sense of discomfort.

  Therefore, in this system, as described below, the efficiency of the MG 12 is reduced in a situation where excess power is generated, and the excess power is consumed by the heat generated by the MG 12.

  As a method of reducing the efficiency of MG12, there is a method of generating heat by applying harmonics, but controllability and responsiveness are poor. For this reason, in this system, paying attention to the relationship between the current phase and the efficiency, the efficiency of the MG 12 is lowered by changing the current phase. Here, the current phase is a phase of the d-axis current and the q-axis current in the vector control in the dq coordinate system in which the d-axis is arranged in the magnet direction and the q-axis is arranged in the direction advanced by π / 2 from the d-axis. In general embedded magnet motors, there is a current phase that maximizes the sum of both magnet torque and reluctance torque due to the mechanical arrangement of the magnets, and there is also a current phase that provides maximum torque and maximum efficiency. However, the efficiency of the MG 12 can be reduced by increasing the phase beyond the current phase that provides the maximum torque and maximum efficiency.

  In order to achieve the desired efficiency, the controller 1 stores an efficiency table that defines the relationship between the current phase and the efficiency as shown in FIG. 2 for each of MG11 and MG12. By referring to these tables, In addition to the current phase that achieves the maximum torque and maximum efficiency, the current phase that achieves the desired low efficiency can be obtained.

  FIG. 3 is a control block diagram of a portion related to excess power calculation of the controller 1. The excess power calculation unit 50 calculates excess power from the driver's required driving force, the target gear ratio of the transmission 13, and the like.

At the time of shifting, the rotation speed of the MG 11 is controlled so that the rotation speed of the engine 10 and the MG 11 becomes the rotation speed after the shifting, and the target torque tT MG11 of the _MG 11 at that time is expressed by the following equation (1):
_{tT MG11 = K × (tN ENG10} -rN ENG10) ··· (1)
It is represented by K is a proportional gain, tN _ENG10 is a target rotational speed that is the rotational speed of the engine 10 after shifting, and rN _ENG10 is an actual rotational speed of the engine 10.

Generated power tP _MG11 of MG11 in this case, the above target MG11 torque tT _MG11 and than the actual rotational speed rN _MG11 = rN _ENG10, the following equation (2):
_{tP MG11 = tT MG11 × rN MG11} × η MG11 ··· (2)
It is represented by _ηMG11 is the power generation efficiency of _{MG11 and} is obtained with reference to an efficiency map as shown in FIG. In addition, a current sensor and a voltage sensor may be attached to the DC line 25, and the efficiency may be estimated from the current and voltage of the DC line 25.

  During the rotation speed control of the MG 11, when the voltage for realizing the target torque of the MG 11 becomes equal to or higher than the battery 23, the switch 24 is opened to disconnect the battery 23. This command is transmitted to the switch 24 control unit 63.

Next, the required power of MG 12 is calculated from the required driving force and the target gear ratio of transmission 13, and based on this, target torque tT MG12 of _{MG 12} is calculated. The required driving force is obtained by referring to a required driving force map prepared in advance based on the accelerator operation amount and the vehicle speed. The required driving force may be set by linear interpolation or the like so that the driving force before and after the shift becomes smooth.

Specifically, the target torque t _{TMG12 of the} MG 12 is expressed by the following equation (3):
_{tT MG12 = (tF Driver / K} 11 -tT clutch13 × R n) ··· (3)
Calculate by tF _Driver is required driving force, K ₁₁ is MG12 drive shaft equivalent to become such a correction _coefficient, tT clutch13 the target engagement torque of the clutch to be used during a shift in the transmission 13, R _n is converted MG12 drive shaft of the target gear ratio Value.

Then, the required power tP _MG12 of the _MG 12 at this time is expressed by the following equation (4):
_{tP MG12 = tT MG12 × rN MG12} × 1 / η MG12 ··· (4)
Calculate by rN _{MG 12} is the actual rotation speed of the MG 12, eta _{MG 12} is the efficiency of MG 12.

Therefore, the generated power tP _{MG11 of} the MG ₁₁ and the required power tP _MG12 of the _{MG 12} are obtained from the expressions (2) and (4), and the relationship of the following expression (5):
tP _MG11 > tP _MG12 (5)
When is established, excess power that is surplus power is generated.

Thus, the controller 1, when the expression (5) is satisfied, tP _{MG 11} = As a tP _MG12, from excessive power calculation unit 50, to change the efficiency of MG11,12 MG 11 control unit 61 and MG12 controller A command (excess power correction command) is issued to 62.

  Note that even if the efficiency of either MG 11 or 12 is reduced, it is possible to suppress excess power from being converted into heat and reflected in the driving force. In this system, the rotational speed control of the engine 10 by the MG 11 is controlled. In order to give priority, first, the efficiency of the MG 12 is lowered, and when the temperature of the MG 12 reaches the upper limit value, the efficiency of the MG 12 is returned to the original value, and the efficiency of the MG 11 is lowered.

  FIG. 4 is a control block diagram of the MG 12 control unit 62.

  The MG 12 control unit 62 includes a normal current phase command unit 92, an excess power generation current command unit 93, and a switching unit 94 that changes the current phase of the MG 12 when an excess power correction command is issued from the excess power calculation unit 50. It consists of. The normal current phase command unit 92 calculates the current phase of the MG 12 at the normal time (for example, the current phase that achieves the maximum torque and the maximum efficiency) based on the actual rotational speed of the MG 12 and the target torque, and the current phase command unit when excessive power is generated. 93 calculates the current phase necessary to realize the target MG12 efficiency based on the target MG12 efficiency (MG12 efficiency command).

  4 shows the MG12 control unit 62, the MG11 control unit 61 has the same configuration.

  5 and 6 are flowcharts showing the contents of the shift control performed by the controller 1. This flow is executed when an upshift command for the transmission 13 is generated.

  According to this, first, in step S101, the required driving force of the driver is estimated by referring to a required driving force map prepared in advance based on the accelerator operation amount and the vehicle speed.

  In step S102, the transmission stage of the transmission 13 is changed to the high speed side (low transmission ratio side), the rotational speed of the MG 11 is controlled, and the rotational speeds of the engine 10 and MG 11 are controlled to the rotational speed after the shift.

In step S103, the generated power tP MG11 of _MG11 is estimated by the above equation (1).

  In step S104, it is determined whether the input / output current of the battery 23 has become about zero. When the voltage of the DC line 25 rises due to the generated power of the MG 11 and approaches the voltage of the battery 23, the input / output current of the battery 23 approaches zero. If the input / output current of the battery 23 is about zero, the process proceeds to step S105, the switch 24 is opened, and the battery 23 is disconnected from the system.

In step S106, the target torque tTMG12 of _MG12 is calculated by the above equation (3).

In step S107, the required power tP _MG12 of the _{MG 12} is calculated by the above equation (4).

In step S108, the generated power tP _MG11 of MG11 and the required power tP _MG12 of _MG12 are compared to determine the occurrence of excess power. When the generated power tP _MG11 of the MG ₁₁ is smaller than the required power tP _{MG1 of the} MG 12 and no excessive power is generated, the process proceeds to step S109, and normal power distribution control for supplying the generated power of the MG 11 to the MG 12 as it is is performed. When excessive power is generated, the process proceeds to step S111 in FIG. 6 in order to suppress the influence of the excessive power on the driving force.

In step S111 in FIG. 6, the target efficiency of the MG 12 is calculated. The target efficiency of the MG ₁₂ is calculated so that the required power of the _{MG 12} is increased by decreasing the efficiency of the _MG 12, and the generated power tP _MG11 of the MG ₁₁ and the required power tP MG12 of the _{MG 12} are equal.

  In step S112, the target phase efficiency of the MG 12 is given as the MG 12 efficiency command to the current phase command unit 93 when the excess power is generated, and the current phase of the MG 12 that realizes the target efficiency with reference to the efficiency table shown in FIG. Current phase).

  In step S113, the switching unit 94 is switched to the excess power generation current phase command unit 93 side, and the current phase of the MG 12 is changed from the normal current phase to the excess power generation current phase calculated in step S112. Thereby, the efficiency of MG12 falls, the emitted-heat amount in MG12 increases, and excess electric power is absorbed.

  In step S114, it is determined whether the temperature of the MG 12 has reached the upper limit value. This is because if the current phase is changed, the amount of heat generated by the MG 12 increases, and if the temperature of the magnet motor rises too much, problems such as demagnetization occur. Therefore, an upper limit value for the control temperature is provided. This is for stopping the change of the current phase.

  When the temperature of MG12 has reached the upper limit value, the process proceeds to step S115, and the current phase of MG11 is changed. By changing the current phase of the MG 11 so as to reduce the efficiency of the MG 11, excess power can be absorbed by the heat generated by the MG 11, and fluctuations in driving force due to the excess power can be subsequently suppressed. If the current phase of MG11 is changed, it will transfer to step S117 and will return the current phase of MG12 to the original.

  In step S116, the presence or absence of excess power is confirmed. When excess power exists, it returns to step S111 and recalculates the target efficiency of MG12. If there is no excess power, the process proceeds to step S117, the current phase of the MG 12 is returned to the normal phase, and the process is terminated.

  With the above control, the generation of excess power can be effectively suppressed. When the current phase of MG11 is changed in step S115, the temperature and excess current of MG11 are determined after the above control is completed. If the temperature of MG11 reaches the upper limit value of MG11 or the excess current disappears, MG11 The current phase is restored.

  In addition, since the efficiency of the MG 12 is reduced by heating after the end of the shift control, when an assist request is made after the end of the shift control, the MG 11 having a relatively mild temperature condition is preferentially used.

  FIG. 7 shows the operation at the time of shifting of the hybrid vehicle according to the present invention. The state in which the shift stage of the transmission 13 is upshifted from the first speed to the second speed is shown.

  When the shift control is started, first, the speed control of the MG 11 is started, and the rotation speeds of the engine 10 and the MG 11 are controlled to the rotation speeds after the shift. At the same time, driving force assist by the MG 12 is started (time t1).

  Thereafter, when the voltage of the DC line 25 becomes equal to or higher than the voltage of the battery 23 and the output of the MG 11 exceeds the battery charge / discharge output limit, the switch 24 is opened to disconnect the battery 23 from the system (time t2).

  When the power generated by the MG 11 rises, the condition of the above equation (5) is satisfied, and excessive power is generated, an efficiency change command for the MG 12 is issued (time t3). Due to the efficiency change of the MG 12, even if an excess current is supplied to the MG 12, the efficiency is reduced, so the excess power is converted into heat and consumed. There is no sense of incongruity.

  As mentioned above, although embodiment of this invention was described, it is as follows when the effect by this invention is put together.

  When the transmission 13 is shifted to the small gear ratio side, the rotational speed of the engine 10 is decreased by causing the MG 11 to perform a power generation operation, and the MG 12 is caused to perform a power running operation by the generated power. At this time, generation of excess power is determined by comparing the generated power of MG 11 and the required power of MG 12, and if it is determined that excess power is generated, at least one of MGs 11 and 12 (the above embodiment) Then, the efficiency of MG12) is reduced. As a result, even if excess power is generated at the time of shifting, the efficiency of MG11 or MG12 is reduced, so that excess power is absorbed by heat generation. As a result, excess power is not reflected in the driving force, so that it can be avoided that a driving force exceeding the required driving force is generated and the driver feels uncomfortable.

  Moreover, in reducing the efficiency of the MGs 11 and 12, by reducing the efficiency by changing the current phase of at least one of the MGs 11 and 12, the excess power can be suppressed with high response. Can do. At this time, if the efficiency of MG12 among MG11 and MG12 is reduced first, unlike the case of reducing the efficiency of MG11, there is no influence on the rotational speed control by MG11, and good shift quality is realized. be able to.

  Further, when a driving force assist request is issued after the end of the shift control, the load of the MG heated by the efficiency reduction control can be reduced by reducing the power distribution ratio of the MGs 11 and 12 that is reducing the efficiency. It is possible to meet the demands of the driver while reducing.

  Also, when shifting the transmission 13 to the smaller gear ratio, if the voltage of the DC line 25 exceeds the voltage of the battery 23 due to the power generated by the MG 11, the switch 24 is opened to disconnect the battery 23 from the system. As a result, the system voltage is not limited by the battery voltage, and high power can be supplied between the motors.

  The above configuration is merely an example of a configuration to which the present invention can be applied, and the present invention can also be applied to hybrid vehicles having other configurations. For example, the battery 23 is not an essential configuration, and the above-described control can be applied to a hybrid vehicle in which the battery is not connected to the DC line 25 connecting the inverters 21 and 22 as shown in FIG. it can.

  Further, in the above embodiment, the excess power generated at the time of shifting is absorbed by the efficiency reduction of MG12, and the efficiency of MG11 is reduced when the temperature of MG12 reaches the upper limit. However, the efficiency of MG11 is reduced first. Alternatively, when the excess power is large, when it is necessary to quickly suppress the excess power, the efficiency of MG11 and MG12 may be decreased at the same time.

  Further, as a method for reducing the efficiency of the MGs 11 and 12, it is preferable to change the current phase in terms of controllability and responsiveness, but other methods may be used, for example, controllability and responsiveness. Although it is inferior, efficiency may be lowered by applying harmonics to cause MGs 11 and 12 to generate heat.

1 is a system configuration diagram of a hybrid vehicle according to the present invention. It is an efficiency table of a motor generator and shows the relationship between current phase and efficiency. It is a control block diagram of the part regarding excess power calculation of a controller It is a control block diagram of an MG12 control unit. It is the flowchart which showed the content of the shift control which a controller performs. It is the flowchart which showed the content of the shift control which a controller similarly performs. 3 is a time chart showing an operation at the time of shifting of the hybrid vehicle according to the present invention. 3 shows another configuration of a hybrid vehicle to which the present invention is applicable.

Explanation of symbols

10 Engine 11 Motor generator (first motor generator)
12 Motor generator (second motor generator)
13 Transmission 14 Drive shaft 15 Drive wheel 23 Battery 24 Switch

Claims (5)

Engine,
A first motor generator connected to the engine;
A transmission for shifting the rotational speeds of the engine and the first motor generator and transmitting them to the drive shaft;
A second motor generator connected to the drive shaft;
A power supply line for electrically connecting the first and second motor generators;
And when the transmission is shifted to a small gear ratio side, the first motor generator is caused to perform a power generation operation to reduce the rotational speed of the engine, and the generated power is supplied to the first motor generator via the power supply line. In the hybrid vehicle that supplies the second motor generator to the power running operation of the second motor generator,
Means for determining the occurrence of excessive power by comparing the generated power of the first motor generator and the required power of the second motor generator when shifting the transmission to a small gear ratio;
Efficiency reduction means for reducing the efficiency of at least one of the first and second motor generators when it is determined that the excess power is generated;
A hybrid vehicle characterized by comprising:   2. The hybrid vehicle according to claim 1, wherein the efficiency reduction unit reduces the efficiency of the first or second motor generator by changing a current phase.   3. The hybrid vehicle according to claim 1, wherein the efficiency reducing unit reduces the efficiency of the second motor generator before the first motor generator. 4.   4. The hybrid vehicle according to claim 1, wherein, when a driving force assist request is issued after the end of a shift, the power distribution ratio to the motor generator that has been reduced in efficiency during the shift is decreased. . A battery connected via a switch in the middle of the power supply line;
Means for opening the switch when the voltage of the power supply line exceeds the voltage of the battery by the power generated by the first motor generator;
The hybrid vehicle according to any one of claims 1 to 4, further comprising:

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