JP2012175769A - Electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a step up-down converter from resonating while driving an electric vehicle with demand driving force.SOLUTION: When voltage step-up abnormality occurs, a target transmission stage is set based on a vehicle speed and a voltage step-up abnormality time transmission relation in which an Lo gear is set in a range where the vehicle speed is equal to or more than value 0 and less than a vehicle speed A, a Hi gear is set in a range where the vehicle speed is equal to or more the vehicle speed A and less than a vehicle speed B, the Lo gear is set in a range where the vehicle speed is equal to or more the vehicle speed B and less than a vehicle speed C, and the Hi gear is set when the vehicle speed is the vehicle speed or more. An inverter for driving a motor is controlled by a selected control mode and a transmission is controlled so that a transmission stage becomes a target transmission stage. This can prevent the number of revolutions of the motor from entering a resonance band while the electric vehicle travels at demand torque for traveling, and can prevent the step up-down converter from resonating.

Description

  The present invention relates to an electric vehicle, and more particularly, an electric motor that outputs power, and a transmission that can transmit power with a change in gear ratio between a rotating shaft of the electric motor and a drive shaft connected to the axle, and An inverter for driving an electric motor, a chargeable / dischargeable battery, and a reactor element that has a reactor element that can boost the power from the battery and supply it to the inverter, and can lower and lower the power from the inverter and supply it to the battery A pressure ratio, a vehicle speed sensor for detecting the vehicle speed, a gear ratio setting means for setting a gear ratio of the transmission based on a predetermined gear shift relationship determined in advance as a relationship between the vehicle speed and the gear ratio, and the detected vehicle speed; A transmission while selecting one control mode from a plurality of control modes including a rectangular wave control mode for controlling an inverter using a rectangular wave voltage and controlling the inverter in the selected mode And control means for controlling the transmission and the inverter and buck-boost converter to travel by driving force demand required to travel while the set gear ratio transmission ratio relates to an electric vehicle equipped with.

  Conventionally, as a motor control device, when the calculated motor speed corresponds to a known motor resonance speed band, the motor control speed is corrected to be lower than the motor resonance speed band, and the motor speed is corrected. A device that controls a motor so as to achieve a control speed has been proposed (see, for example, Patent Document 1). In this apparatus, such control can suppress the motor speed from entering the motor resonance speed band.

JP-A-7-18497

  By the way, the electric power which boosts the electric power from a battery with the buck-boost converter which has an inductor element, supplies the boosted electric power to the inverter which drives an electric motor, changes the motive power from an electric motor with a transmission, and outputs it to an axle, and runs. In an automobile, control is performed in a rectangular wave control mode in which an inverter is controlled using a rectangular wave voltage capable of outputting a relatively large torque from an electric motor so as to travel with a required driving force required for traveling. In such a rectangular wave control mode, it is known that LC resonance is likely to occur when the rotation speed of the motor is within a resonance rotation speed range where LC resonance occurs in the buck-boost converter. In order to suppress such resonance, it is conceivable to control the inverter in the PWM control mode in which the inverter is controlled using the PWM signal without using the rectangular wave control mode, but if the PWM control mode is used, a large torque is output from the motor. Inability to drive with the required driving force.

  The main object of the electric vehicle of the present invention is to suppress the resonance of the buck-boost converter while traveling with the required driving force required for traveling.

  The electric vehicle of the present invention employs the following means in order to achieve the main object described above.

The electric vehicle of the present invention is
A motor that outputs power, a transmission that can transmit power with a change in gear ratio between a rotating shaft of the motor and a drive shaft connected to the axle, an inverter for driving the motor, A chargeable / dischargeable battery, a step-up / down converter that has a reactor element and can boost the power from the battery and supply the battery to the inverter, and can step down the power from the inverter and supply the battery to the battery; A vehicle speed sensor for detecting the transmission, a gear ratio setting means for setting a gear ratio of the transmission based on a predetermined gear shift relationship that is predetermined as a relationship between the vehicle speed and the gear ratio, and the detected vehicle speed, and a rectangular wave voltage While selecting one control mode from a plurality of control modes including a rectangular wave control mode for controlling the inverter using the control, the inverter is controlled in the selected mode. Control means for controlling the transmission, the inverter, and the step-up / step-down converter so as to travel with a required driving force required for traveling in a state where the transmission gear ratio is set to the set gear ratio. In electric vehicles,
The predetermined speed change relationship is a relationship determined in advance as a relationship between a vehicle speed and a gear ratio in which the rotation speed of the electric motor is outside a predetermined resonance rotation speed range as a rotation speed range in which resonance occurs in the buck-boost converter. It is summarized as follows.

  In the electric vehicle according to the present invention, the transmission ratio setting means for setting the transmission ratio of the transmission based on the predetermined transmission relationship predetermined as the relationship between the vehicle speed and the transmission ratio and the detected vehicle speed, and the rectangular wave voltage While selecting one control mode from a plurality of control modes including a rectangular wave control mode for controlling the inverter using the inverter and controlling the inverter in the selected mode, the transmission gear ratio is set to the set gear ratio. The transmission, the inverter, and the step-up / step-down converter are controlled so as to travel with the required driving force required for traveling. The predetermined speed change relationship is a predetermined relationship as a relationship between the vehicle speed and the gear ratio that is outside the range of the resonance speed that is predetermined as the range of the speed at which the rotation speed of the electric motor causes resonance in the buck-boost converter. By making it a thing, it can suppress that a resonance arises in a buck-boost converter, running | running | working with a required drive force.

  In such an electric vehicle of the present invention, the speed ratio setting means is configured so that the step-up / down converter has a vehicle speed and a speed ratio that are different from the predetermined speed relationship when there is no boost abnormality that is an abnormality that cannot boost the power from the battery. A transmission ratio of the transmission is set based on a predetermined normal speed transmission relationship and the detected vehicle speed as a relationship, and based on the predetermined transmission relationship and the detected vehicle speed when the pressure increase abnormality occurs. It is also possible to use a means for setting the transmission ratio of the transmission. When a boosting abnormality occurs, it is possible to suppress the occurrence of resonance in the buck-boost converter while traveling more appropriately with the required driving force.

  Further, in the electric vehicle of the present invention, the transmission is a deceleration when the transmission of power between the drive shaft and the rotation shaft of the electric motor is transmitted to the drive shaft by reducing the rotation speed of the rotation shaft of the electric motor. The transmission is performed by a two-stage shift between a first reduction ratio and a second reduction ratio that is smaller than the first reduction ratio. The predetermined transmission relationship is such that the vehicle speed is greater than or equal to value 0 and greater than value 0. Is the first reduction ratio, when the rotational speed of the electric motor is less than the first vehicle speed, which is the vehicle speed at the lower limit of the resonance rotational speed range, the transmission ratio is set as the first reduction ratio. Is a vehicle speed that is equal to or higher than the first vehicle speed and higher than the first vehicle speed so that the rotation speed of the electric motor becomes the upper limit rotation speed of the resonance rotation speed range when the transmission is set to the first reduction ratio. When the vehicle speed is less than the vehicle speed, the gear ratio is When the vehicle speed is higher than the second vehicle speed and higher than the second vehicle speed and the transmission is set to the second reduction ratio, the rotation speed of the motor is the upper limit rotation speed of the resonance rotation speed range. The transmission ratio is the first reduction ratio when the vehicle speed is less than the third vehicle speed, and the transmission ratio is the second reduction ratio when the vehicle speed is the third vehicle speed or higher. It can also be. In this way, in an electric vehicle equipped with a transmission that performs transmission of power between the drive shaft and the rotating shaft of the electric motor by two-stage shift of the first reduction gear ratio and the second reduction gear ratio, more appropriately by the required driving force. It is possible to suppress the occurrence of resonance in the buck-boost converter while traveling.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 as one Example of this invention. 2 is a configuration diagram showing an outline of the configuration of a step-up / down converter 40. FIG. It is explanatory drawing which shows an example of the speed-change abnormality shift relationship. It is explanatory drawing which shows the relationship between the vehicle speed V, the gear stage, and the rotation speed of the motor MG. It is explanatory drawing which shows the relationship between the rotation speed of the motor MG, and the largest torque which can be output from the motor MG.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 as an embodiment of the present invention. As shown in the drawing, the electric vehicle 20 of the embodiment includes, for example, a motor MG configured as a synchronous generator motor, a drive shaft 26 connected to drive wheels 22a and 22b via a differential gear 24, and a rotation shaft of the motor MG. A transmission 28 that can transmit power with a change in gear ratio, an inverter 30 for driving the motor MG, a battery 32 configured as, for example, a lithium ion secondary battery, and a voltage from the battery 32 And a step-up / down converter 40 capable of stepping up DC power from the battery 32 and supplying the same to the inverter 30 and stepping down DC power acting on the inverter 30 and supplying it to the battery 32. The smoothing capacitor 35 for smoothing the voltage supplied from the step-up / down converter 40 to the inverter 30 and the transmission 28 are controlled. The shift electronic control unit for transmission (hereinafter referred to as the ECU for transmission) 50, the shift signal SR from the shift range sensor 62 for detecting the ignition signal from the ignition switch 60 and the shift lever range, and the depression amount of the accelerator pedal The accelerator opening position Acc from the accelerator pedal position sensor 64 to be detected, the brake position BP from the brake pedal position sensor 66 to detect the depression amount of the brake pedal, the vehicle speed V from the vehicle speed sensor 68, and the rotational position of the rotor of the motor MG. An electronic control unit 55 for inputting a signal from a rotation position detection sensor (not shown) to be detected, a phase current applied to the motor MG detected by a current sensor (not shown), and controlling the inverter 30 and the step-up / down converter 40, Is provided.

  As shown in FIG. 2, the buck-boost converter 40 is connected to switching elements T1 and T2, diodes D1 and D2 connected in parallel to the switching elements T1 and T2, and an intermediate point between the switching elements T1 and T2. And the reactor L and the switching elements T1 and T2 are turned on / off to increase the voltage of the DC power supplied from the battery 32 and supply it to the inverter 30 or to decrease the DC voltage applied to the inverter 30. It is configured as follows.

  The transmission 28 connects and releases the connection between the rotation shaft of the motor MG and the drive shaft 26 and transmits the connection between the two shafts to the drive shaft 26 by reducing the rotational speed of the rotation shaft of the motor MG to two stages. The rotation of the rotation shaft of the motor MG is decelerated at a relatively large first reduction ratio and transmitted to the drive shaft 26 (hereinafter, this state is referred to as a state where the gear stage is Lo gear). The rotation of the rotation shaft is decelerated at a second reduction ratio smaller than the first reduction ratio and is transmitted to the drive shaft 26 (hereinafter, this state is referred to as a state where the gear stage is Hi gear).

  In the electric vehicle 20 of the embodiment configured as described above, the vehicle basically travels by normal drive control described below, which is executed by the electronic control unit 55. In the electronic control unit 55, first, a required torque Tr * to be output to the drive shaft 26 is set according to the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68, and stored in advance. The shift speed corresponding to the vehicle speed V and the required torque Tr * is set as the target shift speed CS * using the shift map that is the relationship between the vehicle speed V, the required torque Tr *, and the shift speed, and the set target shift speed CS * is transmitted to the transmission ECU 50. The transmission ECU 50 that has received the target shift speed CS * controls the transmission 28 so that the shift speed becomes the target shift speed CS *. By such control, the shift stage of the transmission 28 can be set to the target shift stage CS *.

  Further, a value obtained by dividing the set required torque Tr * by the reduction ratio of the target gear stage CS * is set as a torque command Tm * to be output from the motor MG, and the motor MG is driven by the set torque command Tm *. The switching element of the inverter 30 and the switching elements T1 and T2 of the step-up / down converter 40 are subjected to switching control.

  In the switching control of the step-up / down converter 40, the target voltage to be applied to the inverter 30 is set based on the torque command Tm * and the rotational speed of the motor MG so that the required torque Tr * and the rotational speed of the motor MG increase. Then, the switching elements T1 and T2 of the buck-boost converter 40 are on / off controlled so that the voltage supplied from the buck-boost converter 40 to the inverter 30 becomes the target voltage. By such control, it is possible to travel with the required torque Tr * in a state where the speed stage of the transmission 28 is set to the target speed stage CS *.

  In the switching control of the inverter 30, the inverter 30 is switching-controlled by selecting one control mode from a plurality of control modes based on the torque command Tm * of the motor MG and the rotational speed of the motor MG. The control mode of the inverter 30 is a sinusoidal output voltage command with an amplitude equal to or smaller than the amplitude of the triangular wave in the pulse width modulation (PWM) control by the triangular wave comparison in order from a region where the motor rotation speed and torque are low, according to a map (not shown). A sine wave control mode in which the inverter is switched with a PWM signal as a pseudo three-phase AC voltage that is generated and converted, and an overmodulation that generates and converts a sinusoidal output voltage command value with an amplitude that exceeds the amplitude of the triangular wave An overmodulation control mode in which the inverter is switched by a PWM signal as a voltage and a rectangular wave control mode in which the inverter is switched by a rectangular wave voltage having a voltage phase corresponding to the torque command are selected in advance. As the characteristics of the motor MG and the inverter 30, the output response and controllability of the motor MG are improved in the order of the rectangular wave control mode, the overmodulation control mode, and the sine wave control mode, and the outputtable torque is reduced. Since it is known that loss such as switching loss of the motor increases, in the low rotation speed and low torque region, controlling the inverter 30 in the sine wave control mode improves the output responsiveness and controllability of the motor MG. In the high rotation speed and high torque range, the inverter 30 is controlled using the rectangular wave control mode, so that a larger torque can be output and losses such as switching loss of the inverter 30 can be reduced. .

  Next, in the electric vehicle 20 configured as described above, an operation when a step-up / step-down converter 40 has an abnormality in which the voltage from the battery 32 cannot be increased will be described. When the boosting abnormality occurs, the electronic control unit 55 controls the switching elements T1 and T2 of the buck-boost converter 40 so that the buck-boost converter 40 is supplied to the inverter 30 without boosting the power from the battery 32, The inverter 30 is controlled by selecting one of the rectangular wave control mode, the overmodulation control mode, and the sine wave control mode.

  Further, for the transmission 28, a speed increase abnormality shift relationship that is a relationship between the vehicle speed V when the pressure increase abnormality occurs and the gear stage is stored in advance, and when the vehicle speed V is given, the pressure increase abnormality shift relationship is determined. A corresponding shift speed is derived, a target shift speed CS * is set, and transmitted to the transmission ECU 50. The transmission ECU 50 that has received the target shift speed CS * controls the transmission 28 so that the shift speed of the transmission 28 becomes the target shift speed CS *. FIG. 3 is an explanatory diagram showing an example of the speed change abnormality shift relationship, and FIG. 4 is an explanatory diagram showing the relationship between the vehicle speed V, the gear position, and the rotation speed of the motor MG. In FIG. 4, the solid line shows the relationship between the vehicle speed V and the rotation speed of the motor MG when using the speed change abnormality shift relationship, and the alternate long and short dash line shows the shift stage to the Lo gear over the entire range of the vehicle speed. The relationship between the vehicle speed V and the number of rotations of the motor MG in each of the cases where the speed is changed to Hi gear is shown. In relation to the gear change at the time of abnormal pressure increase, the gear position is set to Lo gear in the range where the vehicle speed V is greater than or equal to 0 and less than the value 0, and in the range where the vehicle speed V is greater than or equal to the vehicle speed A and less than the vehicle speed B. Is set to Hi gear, the gear position is set to Lo gear in the range where the vehicle speed V is higher than the vehicle speed B and lower than the vehicle speed C, and the gear position is set to Hi gear when the vehicle speed V is higher than the vehicle speed C. Here, as shown in FIG. 4, the vehicle speed A is the lower limit of the resonance band that is the rotation speed range of the motor MG that causes LC resonance in the buck-boost converter 40 when the transmission 28 is set to Lo gear. It was assumed that the vehicle speed was the rotational speed Rmin. Further, the vehicle speed B is a vehicle speed at which the rotational speed Rmax is the upper limit of the resonance band when the transmission 28 is set to the Lo gear. Furthermore, the vehicle speed C is assumed to be a vehicle speed at which the rotational speed Rmax is the upper limit of the resonance band when the transmission 28 is set to Hi gear. By defining the speed change abnormality shift relationship in this way, the rotation speed of the motor MG is suppressed from becoming the rotation speed within the resonance band.

  FIG. 5 is an explanatory diagram showing the relationship between the rotational speed of the motor MG and the maximum torque that can be output from the motor MG. When the required torque Tr * is relatively large when the pressure increase abnormality occurs, the inverter 30 can be driven at the required torque Tr * by selecting and controlling the rectangular wave control mode. If the rotation speed of the motor MG reaches the rotation speed within the resonance band while the inverter 30 is controlled in the rectangular wave control mode, the LC resonance is generated in the buck-boost converter 40 in a region where the torque output from the motor MG is relatively large. May occur, and the buck-boost converter 40 may not be protected. In the embodiment, by setting the gear position based on the speed change abnormality shift relationship and the vehicle speed V, it is possible to suppress the rotation speed of the motor MG from reaching the rotation speed within the resonance band. Thus, the buck-boost converter 40 can be protected by suppressing the LC resonance. By such control, it is possible to travel with the required torque Tr * and to suppress the resonance of the buck-boost converter 40.

  According to the electric vehicle 20 of the embodiment described above, when a pressure increase abnormality occurs, the gear position is set to the Lo gear in a range where the vehicle speed V is greater than 0 and less than the vehicle speed A, and the vehicle speed V is set to the vehicle speed A. When the vehicle speed A is higher than the vehicle speed B and less than the vehicle speed B, the gear position is set to Hi gear. When the vehicle speed V is higher than the vehicle speed B and lower than the vehicle speed C, the gear position is set to Lo gear and the vehicle speed V is set to the vehicle speed C. In the above, the target shift speed CS * is set based on the relationship between the speed change at the time of abnormal pressure increase in which the shift speed is set to the Hi gear and the vehicle speed V, and one of a plurality of control modes including the rectangular wave control mode is selected. By controlling the inverter 30 in the selected control mode and controlling the transmission 28 so that the shift speed of the transmission 28 becomes the target shift speed CS *, it is possible to travel with the required torque Tr * and to resonate the buck-boost converter 40. It can be suppressed.

  In the electric vehicle 20 according to the embodiment, the step-up abnormality shift relationship is determined as illustrated in FIG. 3. However, when the upshift from the Lo gear to the Hi gear is performed, the step-up abnormality shift relationship illustrated in FIG. 3 is used. When the target shift speed CS * is set and the transmission 28 is downshifted from the Hi gear to the Lo gear, the vehicle speeds in which the vehicle speeds A to C are lowered in place of the vehicle speeds A to C in the speed change abnormality shift relationship of FIG. The target shift speed CS * may be set using D to F. In this way, hunting between upshifts and downshifts can be suppressed.

  In the electric vehicle 20 of the embodiment, the target shift stage CS * is set using the speed change abnormality shift relationship when a pressure increase abnormality occurs. However, when the pressure increase abnormality shift relationship does not occur. May also be used.

  In the electric vehicle 20 according to the embodiment, the transmission 28 can be shifted by two stages, but the transmission 28 can be shifted by three stages or more, or it is a continuously variable transmission that can change gear ratio smoothly and continuously. There may be.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor MG corresponds to “electric motor”, the inverter 30 corresponds to “inverter”, the transmission 28 corresponds to “transmission”, the battery 32 corresponds to “battery”, and the step-up / down converter 40 Corresponds to the “step-up / down converter”, and the electronic control unit 55 that sets the gear ratio using the shift map or sets the gear stage using the step-up abnormality shift relationship of FIG. 3 corresponds to the “speed ratio setting means”. The electronic control unit 55 that controls the inverter 30 in the selected control mode and controls the transmission 28 so that the gear position of the transmission 28 becomes the target gear stage CS * and the transmission ECU 50 become “control means”. Equivalent to.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of electric vehicles.

  20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 28 transmission, 30 inverter, 32 battery, 33, 35 smoothing capacitor, 40 step-up / down converter, 50 ECU for transmission, 55 electronic control unit, 60 ignition switch, 62 shift range sensor, 64 accelerator pedal position sensor, 66 brake pedal position sensor, 68 vehicle speed sensor, D1, D2 diode, L reactor, MG motor, T1, T2 switching element.

Claims (3)

An electric motor that outputs power; a transmission that can transmit power with a change in gear ratio between a rotating shaft of the electric motor and a drive shaft connected to an axle; and an inverter for driving the electric motor; A chargeable / dischargeable battery, a step-up / down converter that has a reactor element and can boost the power from the battery and supply the battery to the inverter, and can step down the power from the inverter and supply the battery to the battery; A vehicle speed sensor for detecting the transmission, a gear ratio setting means for setting a gear ratio of the transmission based on a predetermined gear shift relationship that is predetermined as a relationship between the vehicle speed and the gear ratio, and the detected vehicle speed, and a rectangular wave voltage While selecting one control mode from a plurality of control modes including a rectangular wave control mode for controlling the inverter using the control, the inverter is controlled in the selected mode. Control means for controlling the transmission, the inverter, and the step-up / step-down converter so as to travel with a required driving force required for traveling in a state where the transmission gear ratio is set to the set gear ratio. In electric vehicles,
The predetermined speed change relationship is a relationship determined in advance as a relationship between a vehicle speed and a gear ratio in which the rotation speed of the electric motor is outside a predetermined resonance rotation speed range as a rotation speed range in which resonance occurs in the buck-boost converter. There is an electric car. The electric vehicle according to claim 1,
The speed change ratio setting means is a normal time predetermined as a relationship between a vehicle speed and a speed change ratio different from the predetermined speed change relationship when the step-up / step-down converter does not have a pressure increase abnormality that is an abnormality that cannot increase the power from the battery. A transmission ratio of the transmission is set based on the transmission relationship and the detected vehicle speed. When the pressure increase abnormality occurs, the transmission ratio of the transmission is set based on the predetermined transmission relationship and the detected vehicle speed. Is a means of setting,
Electric car. An electric vehicle according to claim 1 or 2,
The transmission includes a first reduction ratio as the reduction ratio when the transmission of power between the drive shaft and the rotation shaft of the motor is transmitted to the drive shaft by reducing the number of rotations of the rotation shaft of the motor. A two-speed shift with a second reduction ratio smaller than the first reduction ratio,
The predetermined shift relationship is a vehicle speed at which the vehicle speed is greater than or equal to value 0 and higher than value 0, and when the transmission is set to the first reduction ratio, the rotation speed of the electric motor becomes the lower limit rotation speed of the resonance rotation speed range. When the speed ratio is less than a first vehicle speed, the speed ratio is the first speed reduction ratio. When the vehicle speed is equal to or higher than the first vehicle speed and higher than the first vehicle speed, the transmission is set to the first speed reduction ratio. Is less than the second vehicle speed, which is the vehicle speed at which the upper limit of the resonance speed range is reached, the transmission gear ratio is the second reduction ratio, the vehicle speed is greater than or equal to the second vehicle speed, and the first When the transmission is higher than two vehicle speeds and the transmission is set to the second reduction gear ratio, the speed ratio is set to the first gear ratio when the rotation speed of the electric motor is less than the third vehicle speed, which is the vehicle speed that is the upper limit rotation speed of the resonance rotation speed range. The reduction ratio is 1, and the vehicle speed is the third speed. When it is fast or the relationship to the second reduction ratio the transmission ratio,
Electric car.

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