JP4831038B2 - Motor torque control device - Google Patents

Description

  The present invention relates to a motor torque control device that controls output torque of a motor, and more particularly, to a motor torque control device that protects a battery for supplying power to a motor.

In an electric vehicle, in order to protect a battery that supplies electric power to a motor, a technique has been developed that suppresses the output torque of the motor in order to suppress the temperature increase when the temperature of the battery rises above a predetermined value.
Specifically, a temperature sensor is attached to each cell of the battery, and when any of the temperature sensors rises above a predetermined value, the target torque of the motor is multiplied by a gain to suppress the target torque and output Torque is suppressed.

Patent Document 1 discloses a temperature detection unit that detects the temperature of a battery, an abnormality determination unit that determines whether or not a temperature detection value output from the temperature detection unit is greater than a predetermined determination value, and an abnormality determination unit. Discloses a battery temperature rise protection device comprising temperature rise suppression means for stopping the discharge of the battery or reducing the amount of discharge when it is determined that the detected temperature value is greater than the determination value. However, the battery temperature rise protection device of Patent Document 1 is applied to a bicycle with auxiliary power. If this technology is applied to an electric vehicle and the discharge of the battery is stopped suddenly, there is a risk of adversely affecting running. Is not preferable. Moreover, even if it reduces the amount of discharge, according to description of patent document 1, how to reduce is unknown.
Japanese Patent Laid-Open No. 8-171942

By the way, in the above prior art, it is practical to use a relatively inexpensive temperature sensor having a resolution of about 1 ° C. However, if torque is suppressed according to the temperature detected by such a low-resolution temperature sensor, There is a problem that a change in gain with respect to a temperature change of 1 ° C. has a step shape, and a change in torque becomes a step shape, and drivability deteriorates. That is, as shown in FIG. 5, with respect to the upper limit temperature T _U of the battery which is set in advance, (temperature starts torque restriction) torque restriction start temperature T _S and the upper limit temperature T 10 ° C. lower temperature than _U (T _S = T _U −10 ° C.) In the suppression region D ₅ between the upper limit temperature T _U and the torque suppression start temperature T _S , as the battery temperature rises from 100 (%) to 0 (%) If the gain G is set so as to gradually decrease, the gain G changes discontinuously by 10% every 1 ° C. of the resolution of the temperature sensor, and therefore torque suppression is stepped.

Further, there is a demand to set the torque suppression start temperature T _S as high as possible in order to keep driving the motor with as high output as possible. Thus, it is conceivable to set the torque suppression start temperature T _S to a temperature (T _S = T _U −5 ° C.) lower than the upper limit temperature T _U by, for example, 5 ° C. However, when the torque suppression start temperature T _S is set so high, as shown in FIG. 6, the suppression region D ₆ is reduced, and the amount of change in the gain G per 1 ° C. is increased to 20%. That is, when the battery temperature rises by 1 ° C., sudden torque suppression is applied. Therefore, there is a problem that it is difficult to set a high torque restriction start temperature T _S.

Here, if the resolution of the temperature sensor is made finer, such a problem can be avoided, but the battery of an electric vehicle usually has several tens of cells, and of course, when detecting the temperature of each cell, Even when temperature detection is performed for each module in which several cells are combined, a plurality of high-resolution temperature sensors are required, resulting in an increase in cost.
The present invention has been devised in view of such a problem, and a motor torque control device capable of ensuring good drivability while protecting the battery with an inexpensive configuration against the temperature rise of the battery. The purpose is to provide.

In order to achieve the above object, a motor torque control device according to the present invention is a motor torque control device for an electric vehicle that travels by driving electric power from a battery and driving the motor with a predetermined resolution. A temperature detection means for detecting the temperature of the battery and a control means for controlling the output torque of the motor are provided. The control means is detected by the target torque setting section for setting the target torque of the motor and the temperature detection means. A basic gain setting unit that sets a basic gain that suppresses the output torque of the motor in accordance with the temperature of the battery that has been set, and a basic gain setting unit that is set based on a time variation characteristic of the battery temperature that is stored in advance. The target torque set by the target torque setting unit is corrected using the gain correction unit that corrects the basic gain and the correction gain corrected by the gain correction unit. And a instruction unit for outputting a final indicated torque, the temperature of the battery detected by the temperature detecting means is detected to have a predetermined number of times the vibration within a predetermined time period, the target torque with the correction gain It is characterized that you run a correction.

Motor torque control apparatus of the present invention, said the basic gain setting unit, the maximum temperature of the battery which is set in advance, the upper limit temperature target torque suppression start temperature and is stored, which is set to a low temperature side by a predetermined temperature than the When the battery temperature detected by the temperature detection means reaches the target torque suppression start temperature, the gain correction unit passes the time with the basic gain set by the basic gain setting unit as an initial value. Accordingly, it is preferable to gradually decrease the basic gain.

Motor torque control apparatus of the present invention, the time change characteristic of the temperature of the pre-stored battery is preferably a characteristic of the maximum discharge of the battery.
Motor torque control apparatus of the present invention, the time change characteristic of the temperature of the pre-stored battery, it is preferable that the temperature change rate is greater than the temperature rise characteristics of the actual battery.

According to the motor torque control device of the present invention, the basic gain set according to the temperature of the battery detected by the temperature detecting means (hereinafter referred to as the detected temperature) is corrected based on the time variation characteristics of the battery temperature, Since the target torque is corrected using the corrected correction gain, the gain can be continuously changed with respect to the battery temperature change and the time change even if an inexpensive temperature detecting means with low resolution is used. Thus, it is possible to prevent the output torque of the motor from changing stepwise as the battery temperature rises. In addition, it is possible to configure this apparatus only by adding logic in the control means without providing expensive high-resolution temperature detection means or new parts, and this does not cause an increase in cost. Therefore, Ru can to ensure excellent drivability while protecting the battery with an inexpensive configuration for the temperature rise of the battery.
Further, when it is detected that the detected temperature of the battery oscillates a predetermined number of times within a predetermined time, the target torque is corrected using the correction gain, so that it is possible to prevent control fluctuation.

In particular, if the basic gain set by the basic gain setting unit is set as an initial value and the basic gain is gradually decreased with time, the basic gain is corrected so as to better reflect the actual temperature rise of the battery. it is Ru can.
In addition, if the time variation characteristic of the battery temperature is the characteristic at the time of maximum discharge of the battery, the output torque of the motor can be reduced by following the speed of the temperature rise at the time of maximum discharge of the battery quickly. can, Ru can be converted to a temperature of the battery to quickly drop direction.

In addition, if the temperature change rate of the battery temperature is set to be greater than the actual battery temperature rise characteristic, the battery temperature will react quickly to the actual battery temperature rise to ensure the battery temperature Ru can be converted to quickly drop direction.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 are schematic diagrams showing a motor torque control device according to an embodiment of the present invention. FIG. 1 is a block diagram of the motor torque control device, and FIG. 2 is a map of basic gains for torque suppression. FIG. 3 and FIG. 3 are diagrams for correcting the basic gain of FIG.

<Configuration>
As shown in FIG. 1, an electric vehicle includes a traveling motor 1 that rotationally drives driving wheels, a battery (battery pack) 2 that supplies electric power to the motor 1, and a motor 1 and a battery 2. And a plurality of temperature sensors 4 which are attached to each cell (battery) 2a of the battery 2 and detect the temperature of each cell 2a, and a control means 10 which controls the output torque of the motor 1. ing.

The motor 1 functions not only as a motor but also as a generator, and performs regenerative braking when the accelerator is off or the brake is on to recover energy. The battery 2 is integrated with a plurality of cells 2a collected in a battery case 2b.
The inverter 3 is controlled by the control means 10, and power is supplied from the battery 2 to the motor 1 via the inverter 3 in the power running mode, and the rotational force of the drive wheels is converted into power by the motor 1 and converted in the regeneration mode. The electric power is sent to the battery 2 via the inverter 3 so that the battery 2 is charged.

For the temperature sensor 4, a relatively inexpensive one having a relatively low resolution of, for example, 1 ° C. is used. The temperature sensor 4 outputs the temperature (detected temperature) T _det detected based on the temperature (actual temperature) T _real of the cell 2 a to the control means 10. Specifically, for example, when the actual temperature T _{real of the} cell 2 a is 54.3 ° C., the temperature sensor 4 is discarded because the resolution is indistinguishable and outputs 54 ° C. as the detected temperature T _det to the control means 10. It is like that.

The control means 10 is connected to a temperature sensor 4, an accelerator pedal opening sensor (not shown) and a vehicle speed sensor (not shown) on the input side, and connected to the inverter 3 on the output side. A basic target torque setting unit 11, a gain setting unit 12, and an instruction unit 13 are provided.
The basic target torque setting unit 11 sets the basic target torque Trq _O1 of the motor 1 according to the accelerator opening detected by the accelerator pedal opening sensor and the vehicle speed detected by the vehicle speed sensor, and outputs the basic target torque Trq _O1 to the instruction unit 13. It has become.

Gain setting unit 12, the basic gain and basic gain setting unit 12a for setting a G _1, the basic gain G _1, which is set by the basic gain setting unit 12a corrects, the corrected gain (hereinafter, simply referred to as correction gain) G _And a gain correction unit 12 b that outputs ₂ to the instruction unit 13.
Basic gain setting unit 12a stores a map of the base gain G ₁ for suppressing the output torque. This map will be described in detail. As shown in FIG. 2, in the map, the basic gain G ₁ has a maximum value set to 100 (%) and a minimum value set to 0 (%), and the upper limit temperature of the cell 2a. in suppression region D ₁ of the between T _U and the upper limit temperature T _U by the low temperature side to start the set torque restriction temperature T _S (5 ° C. in this embodiment) given temperature than the detected temperature T _det rises Accordingly, it is set to gradually decrease from 100 to 0 at a predetermined rate. Since the resolution of the temperature sensor 4 is 1 ° C., in the suppression region D ₁ , the basic gain G ₁ is stepped (discontinuously) stepped every 1 ° C. as the detected temperature T _det increases. ) It has come to decrease. Further, the basic gain G ₁ can be expressed by the following equation.

Basic gain G ₁ = 100 × (T _U −T _det ) / (T _U −T _S )
Further, the upper limit temperature T _U and the torque suppression start temperature T _S are set in advance, and the torque suppression start temperature T _S is particularly higher than the above-described conventional technique (close to the upper limit temperature T _U) . Set to value). The reason why the torque suppression start temperature T _S is set as high as possible is to meet the desire to drive the motor 1 without reducing the output as much as possible.

Specifically, the upper limit temperature T _U = 60 ° C. and the torque suppression start temperature T _S = 55 ° C. are set here, and the basic gain G ₁ is a ratio of 20% / 1 ° C. in the suppression region D ₁ . In the following description, it is assumed that the setting is gradually decreased. That is, when the detection temperature T _det ≦ 55 ° C., the basic gain G ₁ is held at the maximum value 100, when the detection temperature T _det = 56 ° C., the basic gain G ₁ = 80, and when the detection temperature T _det = 57 ° C., the basic gain. G ₁ = 60, the detected temperature T _det = 58 ° C. base gain G ₁ = 40 when the detected temperature T _det = 59 ° C. base gain G ₁ = 20 when the detected temperature T _det = 60 ° C. base gain G ₁ when = 0 is set. However, the numerical values of the upper limit temperature T _U and the torque suppression start temperature T _S are examples, and are not limited thereto.

The basic gain setting unit 12a selects or calculates the basic gain G ₁ according to the detected temperature T _det detected by the temperature sensor 4 based on the map of the basic gain G ₁ stored in this way, and a gain correction unit. 12b is output.
The gain correction unit 12b, the time rate of change of temperature of the cell 2a is stored (time variation characteristic) k in advance, when the detected temperature T _det is in the suppression area D _1, the gain correction unit 12b, basic gain setting The basic gain G ₁ input from the unit 12 a is corrected according to the above-described temperature change rate k and elapsed time t, and the corrected correction gain G ₂ is output to the instruction unit 13. Further, when the detected temperature T _det is not in the suppression region D ₁ , the gain correction unit 12b does not correct the basic gain G ₁ and uses the value selected and set by the basic gain setting unit 12a as the correction gain G _2. The data is output to the instruction unit 13.

The correction of the basic gain G ₁ when the detected temperature T _det is in the suppression region D ₁ will be described in detail.
The gain correction unit 12b has a timer 12c that counts time, and the timer 12c starts counting when the detected temperature T _det reaches the suppression region D ₁ and when it rises and changes in the suppression region D ₁ . . Then, the gain correction unit 12b, as shown in FIG. 3, based on the time rate of change k of the counted time t and temperature by the timer 12c, basic gain G ₁ is linearly (continuous as time t elapses manner) as reduced, so as to correct the base gain G _1. That is, with the basic gain G ₁ corresponding to the detected temperature T _det as an initial value, the correction gain G ₂ is set by gradually decreasing the basic gain G ₁ over time. This is estimated by actual cell 2a temperature resolution over the accuracy of the time t, it can be regarded to be corrected basic gain G ₁ based on the estimated temperature.

Here, the time change rate k of the temperature is set in advance based on the time change rate k ₀ at the actual maximum discharge obtained in advance by experiments or the like, and is based on the actual time change rate k ₀ . Is also set to a large value. In other words, the time taken for the temperature of the cell 2a to rise by 1 ° C. is set to be shorter than the rise time during actual maximum discharge.
Specifically, when the temperature change rate k ₀ at the actual maximum discharge is calculated as 1 ° C./160 seconds, the time change rate k of the temperature is set to 1 ° C./140 seconds. The value of the time change rate k ₀ at the time of actual maximum discharge depends on the type of the cell 2a and the like, and the value of the time change rate k of the set temperature is an example, It is not limited to.

The count of the timer 12c is started when the detected temperature T _det oscillates a predetermined number of times within a predetermined time and then rises to prevent control flutter. For example, the timer 12c does not start counting only when the detection temperature T _det changes once from 54 ° C. to 55 ° C., and the detection temperature T _det is 54 ° C. → 55 ° C. → 54 ° C. → 55 ° C. → 54 ° C. → 55 ° C. → When it rises after oscillating a predetermined number of times, such as 55 ° C., the timer 12c starts counting, and the basic gain G ₁ changes by 20% / 140 seconds, that is, changes by 1% / 7 seconds. It will decline at a rate. When the count at the point of time t is 70 seconds, the basic gain G ₁ = 100, which is selected from the map shown in FIG. 2, as indicated by one-dot chain lines in FIG. 3, the correction according to the count time t gain G ₂ = The value is corrected to 90. When the count time t exceeds 140 seconds, the correction gain G ₂ is maintained at 80 until the detected temperature T _det rises to 56 ° C. When the detected temperature T _det rises to 56 ° C., the timer 12c starts counting again. When the count time t is 35 seconds, the basic gain G ₁ = 80 selected from the map shown in FIG. As indicated by the alternate long and short dash line, the correction gain G ₂ is corrected to 75 according to the count time t. Similarly, the basic gain G ₁ corresponding to the detected temperature T _det is corrected to the correction gain G ₂ according to the change rate of 1% / 7 seconds and the count time t.

As shown in FIG. 1, the instructing unit 13 multiplies the basic target torque Trq _O1 input from the basic target torque setting unit 11 and the correction gain G ₂ input from the gain correction unit 12 to obtain the final target torque Trq. calculating the _O2, the output torque of the motor 1 is adapted to send an instruction to the inverter 3 becomes the final target torque Trq _O2.
The motor torque control device according to the present invention includes the temperature sensor 4 and the control means 10.

<Action and effect>
Since the motor torque control device according to the embodiment of the present invention is configured as described above, the following operations and effects are obtained.
When the detected temperature T _det of the cell 2a rises above the torque suppression start temperature T _S , the gain G ₂ for suppressing the target torque of the motor 1 is the time change rate of the actual temperature T _real in addition to the detected temperature T _det Since it is also set according to k, the suppression of the output torque of the battery 2 can be smoothly changed with respect to temperature change and time change.

That is, if the resolution of the temperature sensor 4 is low, the detected temperature T _det of the cell 2a changes in steps as shown in FIG. 4, and the gain G is set only in accordance with the detected temperature T _det as in the prior art. The gain G changes stepwise (for example, every 20%). However, according to the present invention, the gain G ₂ is set every 1% in consideration of the temperature change rate k, so that the gain G ₂ can be smoothly changed even when the temperature sensor 4 having a low resolution is used. it can.

Further, since the time change rate k larger than the time change rate k ₀ at the time of maximum discharge is used, the correction gain G has a time allowance before the detected temperature T _det changes to the next rising temperature. ₂ can be made to correspond to the value of the next rising temperature, and the temperature of the cell 3a can be changed quickly and surely by following the temperature rise of the cell 2a quickly.
Therefore, since the target torque can be suppressed with a smooth change, even when the temperature sensor 4 with low resolution is used, there is no sudden change in the output torque, and the temperature of the battery 2 is prevented while preventing the drivability from deteriorating. Can be suppressed. That is, it is possible to configure the motor torque control device only by adding logic in the control means 10 without providing an expensive temperature sensor with high resolution or adding new parts, resulting in an increase in cost. In addition, good drivability can be secured while protecting the battery 2 against the temperature rise of the battery 2.

<Others>
As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the meaning of this invention.
For example, in the above embodiment, a value set larger than the time change rate k ₀ of the temperature at the time of maximum discharge is used as the time change rate k of the temperature of the cell 2a, but is equal to the time change rate at the time of maximum discharge. A value may be used. Moreover, in the said embodiment, although the resolution of the temperature sensor 4 was 1 degreeC, of course, another resolution may be sufficient. Moreover, in the said embodiment, although the temperature sensor 4 was attached for every cell 2a, you may attach for every module which put together several cells 2a.

It is a typical block diagram which shows the motor torque control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the map of the basic gain memorize | stored in the basic gain setting part of the motor torque control apparatus which concerns on one Embodiment of this invention. It is a figure which shows the map of the correction gain of the motor torque control apparatus which concerns on one Embodiment of this invention, Comprising: It is a figure for demonstrating correcting the basic gain of FIG. 2 according to time. It is a figure which compares and shows the gain correct | amended by the motor torque control apparatus which concerns on one Embodiment of this invention, and the gain correct | amended by the motor torque control apparatus which concerns on a prior art. It is a figure which shows the gain map for torque suppression in the motor torque control apparatus which concerns on the prior art of this invention. It is the figure which changed the torque suppression start temperature of the gain map of FIG.

Explanation of symbols

1 Motor 2 Battery (battery pack)
2a cell (battery)
2b Battery case 3 Inverter 4 Temperature sensor (temperature detection means)
10 control unit 11 basic target torque setting unit 12 gain setting unit 12a basic gain setting unit 12b gain correction unit 12c timer 13 instructing unit D _1, D _5, D ₆ suppressing region G ₁ base gain G ₂ correction gain T _det detected temperature T _real actual temperature Trq _O1 basic target torque Trq _O2 final target torque

Claims (4)

A motor torque control device for an electric vehicle that supplies electric power to a motor from a battery and drives the motor to travel,
Temperature detecting means for detecting the temperature of the battery with a predetermined resolution;
Control means for controlling the output torque of the motor,
The control means includes
A target torque setting unit for setting the target torque of the motor;
A basic gain setting unit that sets a basic gain that suppresses the output torque of the motor according to the temperature of the battery detected by the temperature detection means;
A gain correction unit that corrects the basic gain set by the basic gain setting unit based on the time variation characteristics of the temperature of the battery stored in advance;
An instruction unit that corrects the target torque set by the target torque setting unit using the correction gain corrected by the gain correction unit and outputs it as a final instruction torque ;
When the temperature of the battery detected by the temperature detecting means is detected to have a predetermined number of times the vibration within a predetermined time, it characterized that you perform the correction of the target torque with the correction gain, the motor Torque control device. The basic gain setting unit stores a preset upper limit temperature of the battery and a target torque suppression start temperature set to a lower temperature side by a predetermined temperature than the upper limit temperature,
In the gain correction unit, when the temperature of the battery detected by the temperature detection unit reaches the target torque suppression start temperature, the basic gain set by the basic gain setting unit is used as an initial value as the time elapses. The motor torque control device according to claim 1, wherein the basic gain is gradually decreased. The motor torque control device according to claim 1 or 2, wherein the time-varying characteristic of the battery temperature stored in advance is a characteristic at the time of maximum discharge of the battery. 3. The motor torque control device according to claim 1, wherein the time change characteristic of the battery temperature stored in advance is set to have a temperature change rate larger than an actual battery temperature increase characteristic. 4. .

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