JP2020195254A - Motor control device for vehicle - Google Patents

Abstract

To more surely prevent the excessive rotation of a motor while minimizing a decrease in a maximum speed even in an electric vehicle having a large change amount of a vehicle total weight.SOLUTION: A motor control device for a vehicle for controlling a motor 2 configured to be regeneratively controllable includes: a rotation number information acquisition part 41 for acquiring rotation number information of the motor 2; an inverter 10 for limiting the rotation number N of the motor 2 such that the rotation number N of the motor 2 becomes a rotation number upper limit NU or below in the case that the rotation number N of the motor 2 becomes a prescribed threshold Nth or above; a vehicle weight information acquisition part 42 for acquiring the vehicle total weight WGVW of a vehicle 1; and a threshold correction part 43 for performing downward correction of the prescribed threshold Nth for starting the rotation number limit of the motor 2 in the case that the vehicle total weight WGVW becomes a prescribed weight value Wth or above, and performing upward correction of the prescribed threshold Nth for starting the rotation number limit of the motor 2 in the case that the vehicle total weight WGVW becomes less than the prescribed weight value Wth.SELECTED DRAWING: Figure 1

Description

The present invention relates to a vehicle motor control device.

Conventionally, focusing on the viewpoint of reducing the environmental load, the development of an electric vehicle that uses a motor as a driving power source instead of an engine has been progressing. In an electric vehicle, a driving battery is mounted to drive the motor, and power is supplied from the battery to the motor to obtain the power required to drive the vehicle. For example, Patent Document 1 discloses an electric truck that travels by supplying electric power from a mounted battery to a drive motor.

Since such an electric truck has a larger gross vehicle weight (GVW) than a passenger car due to the loaded state, a relatively large regenerative torque is applied when traveling on a downhill road while operating the regenerative brake. I need.

Japanese Unexamined Patent Publication No. 2016-113063

By the way, in the above-mentioned motor, since the upper limit value of the regenerative torque decreases as the rotation speed increases, over-rotation prevention control such as torque cut and application of regenerative torque is performed so as not to exceed the predetermined rotation speed. Need to be done. However, when the load capacity of an electric truck is relatively large, the motor rotation cannot be sufficiently decelerated because the gross vehicle weight increases even if the same over-rotation prevention control as when the vehicle is empty is implemented. As a result, the motor may be damaged. In addition, assuming that the electric truck has a relatively large load capacity, if over-rotation prevention control is performed at a lower speed, the maximum speed of the vehicle will exceed the necessary speed even when the actual load capacity is relatively small. It invites the risk of reducing it.

The present invention has been made in view of such a situation, and an object of the present invention is to minimize a decrease in maximum speed even in an electric vehicle having a large change in gross vehicle weight. An object of the present invention is to provide a vehicle motor control device capable of more reliably preventing over-rotation of a motor.

The vehicle motor control device according to the present invention is a vehicle motor control device for controlling a motor having a predetermined upper limit of the number of rotations and capable of regenerative control by being connected to the drive wheels of the vehicle. When the rotation speed information acquisition unit that acquires the rotation speed information of the motor and the rotation speed of the motor acquired by the rotation speed information acquisition unit become equal to or more than a predetermined threshold value while the vehicle is running. A motor rotation speed limiting unit that limits the rotation speed of the motor so that the rotation speed of the motor is equal to or less than the upper limit value of the rotation speed, a vehicle weight information acquisition unit that acquires the total vehicle weight of the vehicle, and the vehicle weight. When the total weight of the vehicle acquired by the information acquisition unit becomes equal to or greater than a predetermined weight value, the motor rotation speed limiting unit downwardly corrects the predetermined threshold value for starting the rotation speed limitation of the motor, and the total vehicle weight is reduced. A vehicle motor control device including a threshold correction unit that upwardly corrects the predetermined threshold value at which the motor rotation speed limiting unit starts limiting the rotation speed of the motor when the weight value becomes less than a predetermined weight value.

The vehicle motor control device adjusts a predetermined threshold value at which the motor rotation speed limiting unit starts the motor rotation speed limitation based on the gross vehicle weight acquired by the vehicle weight information acquisition unit. As a result, when the gross vehicle weight is relatively heavy, the vehicle motor control device can start limiting the motor rotation speed at a stage where the rotation speed of the motor is low and the regenerative torque is relatively high. Further, when the gross vehicle weight is relatively light, the vehicle motor control device can suspend the start of the motor rotation speed limitation until the stage where the regenerative torque of the motor is relatively low and the rotation speed is high. Therefore, the vehicle motor control device according to the present invention more reliably prevents over-rotation of the motor while minimizing the decrease in the maximum speed even in an electric vehicle having a large change in the gross vehicle weight. be able to.

It is a system block diagram of the vehicle which includes the motor control device for a vehicle which concerns on this invention. It is a graph which conceptually shows the regenerative torque characteristic which concerns on this invention. It is a flowchart which shows the control procedure of the motor control device for a vehicle which concerns on this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the contents described below, and can be arbitrarily modified and implemented without changing the gist thereof. In addition, the drawings used for explaining the embodiments are all schematically showing the constituent members, and are partially emphasized, enlarged, reduced, or omitted in order to deepen the understanding of the constituent members. It may not accurately represent the scale or shape.

FIG. 1 is a system configuration diagram of a vehicle 1 including a vehicle motor control device according to the present invention. The vehicle 1 is a truck (that is, an electric truck) of an electric vehicle including a motor 2 as a traveling drive source. The vehicle 1 is not limited to the truck type, and may be a general passenger vehicle, bus, or other vehicle type as long as it includes a motor as a traveling drive source.

Further, the vehicle 1 according to the present embodiment includes a motor 2, a propeller shaft 3, a differential device 4, a drive shaft 5, a drive wheel 6, an inverter 10, a PDU 11, a battery 12, accessories 13, an accelerator pedal 20, and a brake pedal. It includes 21, an accelerator sensor 22, a brake switch 23, an acceleration sensor 30, and a VCU 40. In addition to the above configuration, the vehicle 1 is appropriately provided with components provided in the conventional electric truck.

The motor 2 is an electric motor that can also operate as a generator, such as a permanent magnet type synchronous motor. A differential device 4 is connected to the output shaft of the motor 2 via a propeller shaft 3, and left and right drive wheels 6 are connected to the differential device 4 via a drive shaft 5. Further, the motor 2 is connected to the battery 12 and the accessories 13 via the inverter 10 and the PDU 11.

Then, the DC power output from the battery 12 via the PDU 11 is converted into AC power by the inverter 10 and supplied to the motor 2, and the driving force generated by the motor 2 is transmitted to the drive wheels 6 to drive the vehicle 1. Run (power running control). Further, for example, when the vehicle 1 is decelerating or traveling on a downhill road, the motor 2 functions as a generator by reverse driving from the drive wheel 6 side (regeneration control). In this case, the negative driving force generated by the motor 2 is transmitted to the driving wheel 6 side as braking force, and the AC power generated by the motor 2 is converted into DC power by the inverter 10 to convert the PDU 11 to DC power. The battery 12 is charged via.

Here, the inverter 10 functions as a "motor rotation speed limiting unit" that limits the rotation speed N of the motor 2 so that the motor 2 is not damaged by over-rotation when the vehicle 1 travels on a downhill road, for example. More specifically, the inverter 10, to fit below the rotational speed upper limit value N _U breakage risk of the motor 2 occurs, the limit of the rotational speed N at the stage where the rotational speed N of the motor 2 is equal to or larger than a predetermined threshold value Nth Start. Details of the over-rotation prevention control of the motor 2 will be described later. Further, in the present embodiment, the "vehicle motor control device" is configured by the inverter 10 and the VCU 40.

The PDU 11 is a power distribution unit connected to various electric devices mounted on the vehicle 1, and distributes high-voltage power supplied from the battery 12 to the motor 2 and auxiliary machinery 13. The PDU 11 may be connected to a low-voltage battery (neither shown) via a DC-DC converter, which is suitable for a device driven by a low voltage such as VCU40, which will be described later. Power can be supplied.

The battery 12 is a secondary battery that mainly supplies electric power as an energy source for driving the vehicle 1, and is, for example, a lithium ion battery. Further, the auxiliary machinery 13 is an electric device such as an air conditioner or a power steering device, and operates by supplying high-voltage power via the PDU 11.

The accelerator pedal 20 and the brake pedal 21 are provided in the driver's seat of the vehicle 1 and are operation mechanisms for the driver to perform acceleration operation and deceleration operation, respectively. When the driver of the vehicle 1 depresses the accelerator pedal 20, the accelerator sensor 22 detects the amount of operation of the accelerator pedal 20 and transmits the accelerator opening degree Ac to the VCU 40 described later. Further, when the driver of the vehicle 1 depresses the brake pedal 21, the brake switch 23 detects the operation amount of the brake pedal 21 and transmits the operation amount to the VCU 40.

The acceleration sensor 30 detects the acceleration of the vehicle 1 at any time during the period when the ignition of the vehicle 1 is ON and transmits it to the VCU 40.

The VCU 40 includes an input / output device, a storage device (ROM, RAM, etc.) used for storing control programs, control maps, etc., a central processing unit (CPU), a timer counter, and the like (none of which are shown). It is a vehicle control unit for comprehensively controlling the entire vehicle 1 by monitoring and controlling the state of various components mounted on the vehicle 1.

More specifically, the VCU 40 calculates the required torque based on the information such as the accelerator opening degree Ac transmitted from the accelerator sensor 22, and controls the torque T and the rotation speed N of the motor 2 to control the driver. The vehicle 1 is accelerated at an acceleration corresponding to the stepping operation on the accelerator pedal 20 of the above. Further, the VCU 40 regeneratively controls the motor 2 based on the amount of brake operation or the like, and also controls a brake mechanism (not shown) as necessary, and negative acceleration according to the driver's stepping operation on the brake pedal 21. Decelerates vehicle 1. Further, the VCU 40 manages the charging / discharging of the battery 12 by the power running control and the regenerative control by performing the power control via the PDU 11.

In particular, the VCU 40 according to the present embodiment includes a rotation speed information acquisition unit 41, a vehicle weight information acquisition unit 42, and a threshold value correction unit 43 as a mechanism for performing regenerative control for the motor 2.

The rotation speed information acquisition unit 41 acquires rotation speed information of the motor 2 while the vehicle 1 is traveling via a rotation speed sensor (not shown) provided in the motor 2. When the rotation speed N of the motor 2 acquired by the rotation speed information acquisition unit 41 becomes the predetermined threshold value Nth or more, the motor rotation speed limitation described later is started.

The vehicle weight information acquisition unit 42 estimates the weight of the vehicle 1 that changes depending on the loading state of cargo handling in the vehicle 1, the number of passengers, and the like, based on the acceleration sensor 30, the torque T and the rotation speed N of the motor 2. More specifically, the vehicle weight information acquisition unit 42 calculates the force acting on the vehicle 1 by using the above-mentioned information of the motor 2 and the gradient data of the road on which the vehicle 1 travels, and the acceleration sensor 30. By using the acceleration information obtained in the above, the gross vehicle weight _WGVW of the vehicle 1 is calculated through the equation of motion for the vehicle 1. Here, the "gross vehicle weight" in the present application means a variable value that changes depending on the state of the total weight including the vehicle body weight of the vehicle 1, the load, the passengers, and the like.

The threshold correction unit 43 starts limiting the rotation speed N when the rotation speed N of the motor 2 becomes equal to or higher than a predetermined threshold value Nth. In the over-rotation prevention control of the inverter 10, the gross vehicle weight W is as described in detail later. Adjust the timing to start the rotation speed limit based on the size of _GVW .

FIG. 2 is a graph conceptually showing the regenerative torque characteristics according to the present invention. In FIG. 2, it is a maximum regenerative torque curve when the horizontal axis is the rotation speed N of the motor 2 and the vertical axis is the regenerative torque T of the motor 2. That is, the maximum regenerative torque curve of FIG. 2 represents a change in the maximum regenerative torque value that can be set according to the rotation speed of the motor 2, and shows how the upper limit value of the regenerative torque decreases as the rotation speed increases. There is.

Here, the converted value to the amount of energy of the regenerative torque value recovered by the regenerative control in the case where the vehicle 1 is descending traveling slope and T _L, the rotational speed upper limit value N _U a rotational speed N of the motor 2 at that time And. At this time, when the rotational speed N of the motor 2 is equal to or greater than the rotational speed upper limit value N _U, the motor 2, it is impossible to decelerate the vehicle 1 by the regenerative brake. Therefore, inverter 10, so that the rotational speed N of the motor 2 does not reach the rotational speed upper limit value N _U, the rotational speed N starts to overspeed prevention control at step becomes equal to or greater than a predetermined threshold value Nth.

Set More specifically, the predetermined threshold value Nth, the vehicle weight information acquisition unit of the vehicle 1 42 acquires gross vehicle weight W _GVW, depending on whether or not heavier than a predetermined weight value Wth is arbitrarily set in advance Will be done. In the present embodiment, the predetermined threshold value Nth, the second rotation corresponding to the case relative first rotating speed N ₁ gross vehicle weight W _GVW corresponding to the case is light _or relatively gross vehicle weight W _GVW heavy It is set to any number N _2.

That is, when the gross vehicle weight _WGVW of the vehicle 1 is relatively light, even if the over-rotation prevention control is started when the rotation speed N of the motor 2 reaches the first rotation speed N ₁ , it corresponds to this. it is possible to suppress an increase in rotational speed N of the motor 2 in the first regenerative torque value T _1, can be controlled so as not reach the rotational speed upper limit value N _U. Further, when the gross vehicle weight _WGVW of the vehicle 1 is relatively heavy, this is dealt with by starting the over-rotation prevention control when the rotation speed N of the motor 2 reaches the second rotation speed N ₂ . it is possible to suppress an increase in rotational speed N of the motor 2 in the second regenerative torque value T _2, can be controlled so as not reach the rotational speed upper limit value N _U.

The over-rotation prevention control in the inverter 10 is not limited to the above-mentioned method of applying regenerative torque, and various control methods such as torque cut and three-phase short-circuit control can be applied.

Subsequently, a procedure in which the VCU 40 and the inverter 10 perform over-rotation prevention control of the motor 2 will be described. FIG. 3 is a flowchart showing a control procedure of the vehicle motor control device according to the present invention. The VCU 40 starts the control procedure according to the flowchart of FIG. 3 when the ignition of the vehicle 1 (not shown) is switched from OFF to ON and activated.

When the VCU 40 is activated, the threshold value correction unit 43 sets a predetermined threshold value Nth for starting the rotation speed control of the motor 2 to the second rotation speed N ₂ and sets it as an initial value (step S1). That reduction, in the running at the stage of gross vehicle weight W _GVW of the vehicle 1 has not been acquired, on the assumption that a gross vehicle weight W _GVW is not less than a predetermined weight value Wth, the relatively large regenerative torque during deceleration the predetermined threshold value Nth is set to a second rotational speed N ₂ starts running so that it can be.

Further, the vehicle weight information acquisition unit 42 starts estimating the gross vehicle weight _WGVW of the vehicle 1 by the above method (step S2). However, in order to secure the estimation accuracy for the gross vehicle weight W _GVW is gross vehicle weight W _GVW of the vehicle 1 while accumulating the information obtained from it is necessary to calculate the in the running state until the complete weight estimate Will take some time. That is, in the weight estimation, the gross vehicle weight _WGVW is basically continuously calculated by using the acceleration accompanying the running of the vehicle 1, but the first estimated value is calculated after the weight estimation is started. It takes, for example, a running time of about 1 to 2 minutes.

Therefore, VCU 40 determines whether the vehicle gross weight _{W GVW} of the vehicle 1 is acquired in step S2 (step S3). Further, the vehicle weight information acquisition unit 42 continues the weight estimation in step S2 until the gross vehicle weight _WGVW is acquired (No in step S3).

When it is determined that the gross vehicle weight W _GVW has been acquired (Yes in step S3), the threshold value correction unit 43 determines whether or not the estimated gross vehicle weight W _GVW is less than the above-mentioned predetermined weight value Wth. (Step S4).

The threshold value correction unit 43, gross vehicle weight _{W GVW} maintains a predetermined threshold value Nth to the second rotational speed _{N 2} when the predetermined weight value Wth or more (step S5), and a gross vehicle weight _{W GVW} predetermined weight sets a predetermined threshold value Nth to first rotational speed _{N 1} in the case is less than the value Wth (step S6). That is, the threshold value correction unit 43 selects a predetermined threshold value Nth to be set at the time of deceleration according to the gross vehicle weight _WGVW of the vehicle 1.

Here, as described above, the vehicle weight information acquisition unit 42 continues to calculate the gross vehicle weight _WGVW using the acceleration associated with the running of the vehicle 1, and therefore the gross vehicle weight is a newly calculated estimated value. The _WGVW is continuously updated (step S7).

Further, the VCU 40 determines whether or not the ignition of the vehicle 1 has been switched to OFF (step S8), and ends the control procedure of the vehicle motor control device when the ignition is turned OFF (Yes in step S8). ).

On the other hand, during the period when the ignition of the vehicle 1 is ON (No in step S8), the routine from step S4 to step S8 is continued. That is, the threshold value correction unit 43 adjusts the predetermined threshold value Nth related to the rotation speed of the motor 2 according to the gross vehicle weight _WGVW continuously updated by the vehicle weight information acquisition unit 42.

More specifically, the vehicle controller for a motor, when the gross vehicle weight W _GVW is equal to or larger than a predetermined weight value Wth is under the control of the threshold value correcting unit 43, the inverter 10 starts the rotational speed limiting motor 2 the predetermined threshold value Nth for the first rotational speed _{N 1} to the second rotational speed _{N 2} down correction. The vehicle motor control device, if the gross vehicle weight W _GVW is less than the predetermined weight value Wth is under the control of the threshold value correcting unit 43, the inverter 10 starts the rotational speed limiting motor 2 a predetermined The threshold value Nth is upwardly corrected from the second rotation speed N ₂ to the first rotation speed N ₁ .

As described above, in the vehicle motor control device according to the present invention, the rotation speed of the motor 2 in which the inverter 10 starts limiting the motor rotation speed based on the gross vehicle weight _WGVW acquired by the vehicle weight information acquisition unit 42. The predetermined threshold Nth for N is adjusted. As a result, when the gross vehicle weight _WGVW is relatively heavy, the vehicle motor control device can start the motor rotation speed limitation at a stage where the rotation speed N of the motor 2 is low and the regenerative torque is relatively high. Further, when the gross vehicle weight _WGVW is relatively light, the vehicle motor control device can suspend the start of the motor rotation speed limitation until the stage where the regenerative torque of the motor 2 is relatively low and the rotation speed N is high. .. Therefore, the vehicle motor control device according to the present invention more reliably over-rotates the motor while minimizing the decrease in the maximum speed even in an electric vehicle having a large change in the gross vehicle weight _WGVW. Can be prevented.

Although the description of the embodiment is completed above, the present invention is not limited to the above-described embodiment. For example, in the above embodiment, an embodiment in which either the first rotation speed N ₁ or the second rotation speed N ₂ is selected according to one predetermined weight value Wth is illustrated, but for example, three or more by two or more threshold values. You may select from the rotation speed N.

More specifically, for example, if you set the first predetermined weight value Wth1 and second predetermined weight value Wth2 against gross vehicle weight _{W GVW,} first rotational speed _{N 1} is selected in the range of W GVW <Wth1 , in the range of Wth1 ≦ _W GVW <Wth2 selected second rotational speed _{N 2 is} in the range of _{W GVW} ≧ Wth2 may be the third rotational speed _{N 3} is selected.

1 Vehicle 2 Motor 10 Inverter 30 Accelerometer 40 VCU
41 rpm information acquiring unit 42 vehicle weight information acquisition unit 43 threshold value correcting unit W _GVW gross vehicle weight N _U rpm limit Nth predetermined threshold Wth predetermined weight value

Claims (1)

A vehicle motor control device for controlling a motor that has a predetermined upper limit of the number of revolutions and is configured to be regeneratively controllable by being connected to the drive wheels of the vehicle.
When the rotation speed information acquisition unit that acquires the rotation speed information of the motor and the rotation speed of the motor acquired by the rotation speed information acquisition unit become equal to or more than a predetermined threshold value while the vehicle is running, the motor A motor rotation speed limiting unit that limits the rotation speed of the motor so that the rotation speed is equal to or less than the upper limit of the rotation speed.
A vehicle weight information acquisition unit that acquires the gross vehicle weight of the vehicle,
When the gross vehicle weight acquired by the vehicle weight information acquisition unit becomes equal to or greater than a predetermined weight value, the motor rotation speed limiting unit downwardly corrects the predetermined threshold value at which the motor rotation speed limiting starts, and the vehicle A vehicle motor control device including a threshold correction unit that upwardly corrects the predetermined threshold value at which the motor rotation speed limiting unit starts limiting the rotation speed of the motor when the total weight becomes less than a predetermined weight value.

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