JP5493384B2 - Motor heat generation prevention control device - Google Patents

Description

  The present invention relates to an apparatus for preventing heat generation caused by a motor being driven around.

  When the motor rotates, a counter electromotive force is generated. Therefore, when the motor is rotated, energy is consumed due to the generation of the counter electromotive force, and the motor generates heat. In order to reduce such energy loss, for example, the control device described in Patent Document 1 controls the field current and the energization direction of the electric motor when the accompanying rotation of the electric motor is detected. Thus, the torque of the electric motor is controlled to a value in the opposite direction to the accompanying rotation to generate a brake torque, thereby preventing the accompanying rotation of the electric motor.

  Further, since the back electromotive force in the motor is generated by the relative rotation of the rotor and the stator, in the invention described in Patent Document 2, when the motor is rotated, the stator is also rotated. As a result, the electromotive force is avoided by preventing the stator and the rotor from rotating relative to each other during the rotation. Furthermore, in the invention described in Patent Document 3, in order to prevent the motor from being rotated at high speed and generating heat and becoming high temperature, the motor, the drive wheel, It is comprised so that the power transmission between may be interrupted | blocked.

  In addition, the heat generated by the motor is also actively used conventionally. For example, in Patent Document 4, when the temperature of the wet clutch is low, the heat is generated by energizing the rotor magnetic field coil to generate heat. Describes a device configured to increase the temperature of the clutch.

JP 2006-14451 A JP-A-2005-124253 JP 2007-55439 A JP 2006-325342 A

  Since the apparatus described in Patent Document 1 is configured to stop the rotation of the electric motor by causing the electric motor to generate a torque that counteracts the accompanying torque, the rotation of the rotor shaft of the motor and the rotation connected thereto. A large torque acts on the shaft, and there is a possibility that the apparatus becomes large in size or maintains its durability in order to maintain its strength. In addition, depending on the configuration of the device, inevitably accompanying rotation occurs, and if the accompanying rotation is stopped, the entire device is configured to stop, the configuration described in Patent Document 1 is adopted. Can not do it.

  Further, the device described in Patent Document 2 is configured to rotate the stator and needs to include a fixing means such as a brake that selectively prevents the rotation. Therefore, in addition to the fixing means such as a brake, a device for controlling the fixing means must be provided. Therefore, the configuration of the entire apparatus may be increased in size and control may be complicated. Such a situation is the same for the device described in Patent Document 3, and a mechanism such as a clutch for releasing the connection between the electric motor and the driving wheel at the highest speed stage and a device for controlling the mechanism must be provided. As a result, the configuration of the entire apparatus may be increased in size and control may be complicated.

  The present invention has been made paying attention to the above technical problem, and an object of the present invention is to provide a control device capable of avoiding or suppressing the heat generation of the motor due to the accompanying rotation.

In order to achieve the above object, the present invention provides a heat generation prevention control device for a motor that changes its magnetic field by being forcedly rotated by an external force and generates heat by the change of the magnetic field. When the motor rotation speed during rotation accompanying the rotation of the motor is greater than a predetermined threshold, the magnetic field generated in the motor due to the rotation, or in the direction to cancel the heat generated by the change in the magnetic field as magnetic field is generated, the current of the motor controlled by the inverter, reducing motor losses, and is characterized in that it comprises a motor low loss control means for increasing the inverter loss .

  When the motor is forcibly rotated by an external force, the magnetic field acting on the coil may change due to the relative movement between the rotor and the stator, even if the coil is not energized. According to the present invention, when the motor rotates along with the rotation of the other rotating member, the magnetic field acting on the coil does not change even if the rotor and the stator rotate relative to each other, and the heat is generated. The current is controlled so as not to occur. Therefore, according to the present invention, it is possible to prevent or suppress an increase in the temperature of the motor due to the accompanying rotation.

It is a flowchart for demonstrating the example of control performed with the control apparatus which concerns on this invention. FIG. 2 is a diagram showing motor loss, inverter loss, and total loss when the control shown in FIG. 1 is executed. It is a flowchart for demonstrating the other example of control performed with the control apparatus which concerns on this invention. It is a flowchart for demonstrating the further example of control performed with the control apparatus which concerns on this invention. It is a diagram which shows the loss at the time of accompanying when the motor low loss control which concerns on this invention is not performed.

The present invention is a control device for a motor that can be accompanied. Here, the drag motion is that other rotary member motor is connected is communicated to the child rotating motor is rotated, an example of this type of motor, in JP 2008-184111 It is the described in-wheel motor. Briefly describing the configuration, the in-wheel motor is a motor that is disposed inside or in the vicinity of the wheel in the vehicle and directly drives the wheel, and its casing is supported by the lower arm constituting the suspension mechanism. In the casing, a motor and a speed reducer are connected. The wheel is rotatably supported at the front end portion of the casing via a bearing, and the output shaft of the speed reducer is coupled to the wheel (more specifically, the hub). And the motor is a permanent magnet type synchronous motor, a coil is arranged along the inner peripheral surface of the casing, and it is a stator, and a rotor is rotatably arranged on the inner peripheral side, A permanent magnet is attached to the outer periphery of the rotor.

  Therefore, when a vehicle equipped with this type of in-wheel motor is coasting, or when the vehicle is traveling by driving another drive wheel by an engine, the motor rotates as the wheel rotates. In that case, if the coil is not energized, the magnetic field acting on the coil changes due to the relative rotation between the rotor having the permanent magnet and the stator, and heat is generated by the electromotive force and the copper loss and iron loss in the coil. Will occur. An example of this is shown in FIG. 5, and the loss in the motor (motor loss) increases as the accompanying rotational speed increases. In contrast, the loss in the inverter that controls the motor current (INV loss) is substantially constant regardless of rotation. As a result, the total loss is the sum of the motor loss and the INV loss, as indicated by the broken line in FIG.

  On the other hand, the control device according to the present invention is configured to reduce motor loss and suppress heat generation. The control is a control for canceling the change in the magnetic field due to the rotation of the rotor (permanent magnet) by energizing the coil (stator) even if it is accompanied. FIG. 1 shows an example of the control. First, it is determined whether or not the rotational speed of the motor being rotated is greater than a predetermined threshold value (step S1). As described above, the motor loss increases with an increase in the accompanying rotational speed, and the heat generation amount increases accordingly. Therefore, the threshold value is preferably set to a value equal to or higher than the rotational speed at which the heat generation amount is a problem. .

  If a positive determination is made in step S1 because the motor rotation speed is greater than the threshold value, it is determined whether or not the temperature of the in-wheel motor unit including the motor is higher than the temperature-related threshold value. (Step S2). This is because when the temperature of the unit is low, it is not necessary to perform control for cooling, and when the temperature is lower than the appropriate temperature, it is preferable to raise the temperature by heat generated by the accompanying.

  If the determination in step S2 is affirmative because the temperature of the in-wheel motor unit is higher than the threshold value, motor low loss control is executed (step S3). This motor low loss control is a control for reducing the loss due to heat generated by the change of the magnetic field due to the relative rotation between the stator and the rotor. Specifically, the motor low loss control is based on the relative rotation between the stator and the rotor. This is current control for controlling the current of the stator coil so as to cancel the change in the magnetic field caused or the heat generated therewith.

  On the other hand, when a negative determination is made in step S1 because the motor rotation speed due to rotation is equal to or less than the threshold value, normal control is executed (step S4). Here, the normal control is control in which current is not supplied to the coil so as to cancel the change in the magnetic field during the rotation described above. On the other hand, if a negative determination is made in step S2 because the temperature of the unit is equal to or lower than the threshold value, the process proceeds to step S4 and normal control is executed. Therefore, since the current is not passed through the coil at the time of the follow-up in either case where the negative determination is made in step S1 or the negative determination in step S2, energy consumption is not caused. This is advantageous in improving fuel efficiency in vehicles.

  As described above, in the control device according to the present invention, when the motor rotates, the change in the magnetic field is canceled out by energization of the coil, so that the copper loss and iron loss in the motor can be reduced. Thus, the temperature rise of the motor can be suppressed by preventing or suppressing the heat generation. In this case, a loss may occur in the inverter that controls the motor current, and the temperature may increase. This is shown in a diagram in FIG. 2. When the rotational speed of the motor to be rotated exceeds the above-described threshold value and the unit temperature at that time exceeds the threshold value, the above-described motor low loss control is started. Is done. The number of rotations is indicated as “control start threshold” in FIG. Therefore, an increase in motor loss is suppressed on the higher rotation speed side than this rotation speed. On the other hand, the inverter loss increases as the rotational speed increases. As a result, the total loss is somewhat increased compared to the normal control without motor low loss control. However, since motor loss is reduced, motor temperature rise and overheating can be prevented. Further, in the control device according to the present invention that performs the above-described control, the motor low loss control in which the total loss is larger than that in the case of the normal control is performed when the rotational speed of the motor to be driven exceeds a threshold value and Since it is limited to the case where the temperature of the motor unit exceeds the threshold, even if energy is consumed to suppress the temperature rise of the motor, the energy consumption is limited, so that energy loss for cooling the motor is possible. It can be reduced as much as possible. Even if the inverter loss increases and the amount of heat generated in the inverter may increase, the inverter is normally cooled, so that the temperature does not increase particularly. As a result, the in-wheel motor unit relates to the in-wheel motor unit. The cooling system can be reduced in size.

  In the in-wheel motor described in Japanese Patent Application Laid-Open No. 2008-184111 described above, the motor unit and the brake are disposed close to each other, so that the heat of the brake may affect the temperature of the motor. Therefore, when the control device according to the present invention is applied to the in-wheel motor described in Japanese Patent Application Laid-Open No. 2008-184111, it is preferable to perform control in consideration of the state of brake operation. An example of the control is shown in FIG. 3. First, it is determined whether or not the brake is ON (step S11). This can be determined by a signal from a brake switch normally provided in the vehicle. If the determination in step S11 is affirmative because the brake is on, motor low loss control is executed (step S12). That is, when the motor rotates with the brake operated, the coil (stator) is energized so as to cancel the change in the magnetic field accompanying the rotation. In other words, in a state where heat is generated in the brake and the effect may affect the motor, the motor loss and the amount of heat generated by the follow-up are controlled so that the motor temperature rise and overheating are prevented. Or it is suppressed.

  On the other hand, if a negative determination is made in step S11 because the brake is not ON, it is determined whether or not a predetermined time has elapsed since the brake was turned OFF (step S13). The predetermined time is a time that is experimentally determined as a time required for the brake temperature to decrease to a level that does not affect the motor, or a time that is determined by simulation. The time may be a fixed value or may be a variable value that is set to be shorter as the vehicle speed increases. If the elapsed time from the brake OFF does not exceed the predetermined time, and a negative determination is made in step S13, the process proceeds to step S12 described above, and motor low loss control is executed. This is to prevent or suppress the temperature rise of the motor.

  In addition, if the elapsed time from the brake OFF exceeds a predetermined time and it is determined affirmative in step S13, it is considered that the thermal influence from the brake is not so problematic that the normal control is performed. Is executed (step S14). Therefore, when the control shown in FIG. 3 is executed, it is possible to prevent or suppress the temperature rise or overheating of the in-wheel motor that is easily affected by the heat of the brake.

  The left and right independent motors in a vehicle may be used in combination with an internal combustion engine such as a gasoline engine. In that case, in a so-called lateral type vehicle in which the engine is arranged in the width direction of the vehicle, the engine and motor drive system And will approach. In such a case, it is considered that the heat of the engine is likely to affect the motor drive system. Therefore, when the apparatus according to the present invention is applied to the cooling control of the motor in a vehicle of the type in which the engine is placed horizontally, It is preferable to be configured to perform. FIG. 4 shows an example of the control. First, it is determined whether or not the engine is operating at a high load (step S21). This determination is based on whether the engine heat is being applied to the motor located near the engine, such as whether the engine temperature is high, whether the temperature is high, or whether the engine is generating a large amount of heat. This is for determining whether or not there is an influence, or whether or not the heat influence is large, and can be determined based on the accelerator opening, the throttle opening, the intake air amount, and the like.

If a positive determination is made in step S21 because the engine is operating at a high load, the heat influence on the motor is large, and this was determined affirmatively in step S11 shown in FIG. If it the same as the status of, and thus this case, the motor low loss control is executed (step S22). This motor low-loss control is the same control as in each of the specific examples described above. For this reason, if the motor temperature is likely to increase due to the influence of the engine heat, the coil current is controlled so as to suppress the change in the magnetic field when the motor rotates or the accompanying heat generation. Temperature rise is prevented or suppressed.

On the other hand, the engine if a negative determination is made in step S21 by not high load OPERATION is whether or not the engine oil temperature is above a predetermined threshold is determined (step S23). This is for determining whether or not the engine temperature is already high. Therefore, if the engine oil temperature is higher than the threshold value and the determination in step S23 is affirmative, it is determined that the engine heat has an effect on the motor and increases the motor temperature. The process proceeds to step S22 described above, and motor low loss control is executed.

  On the contrary, if the engine oil temperature is below the threshold value and a negative determination is made in step S23, it is determined whether or not the radiator fan is OFF (step S24). That is, it is determined whether or not the engine is being actively cooled. Therefore, when a positive determination is made in step S24, the forced cooling of the engine coolant is not performed. When the radiator fan is driven, cooling air is applied not only to the radiator but also to an engine that is raised in the vicinity of the radiator and a motor that is disposed at a position close to the engine. Therefore, if the radiator fan is OFF, the cooling air is not positively applied to the engine, the motor, or the motor drive system. In such a case, the engine temperature is likely to rise. Proceeding to S22, motor low loss control is executed. On the other hand, when the radiator fan is ON and forced air cooling of the engine coolant is being executed, normal control is executed (step S25). This is because there is little thermal influence from the engine to the motor.

  Therefore, when the control shown in FIG. 4 is executed, it is possible to prevent or suppress an increase in temperature when the motor is rotated. Since it is executed only when it is estimated or expected to affect the motor, even if energy is consumed for the motor low loss control, the consumption amount can be reduced as much as possible.

Claims (1)

In the heat generation prevention control device for a motor that changes the magnetic field by being forced to rotate by an external force and generates heat by the change of the magnetic field,
Changes in the magnetic field generated in the motor due to the rotation, or changes in the magnetic field when the motor rotation speed during the rotation in which the motor rotates as the other rotation member rotates is greater than a predetermined threshold value as the magnetic field is generated in the direction to cancel the heat generation due to the current of the motor controlled by the inverter, reducing motor losses, and, it has a motor low loss control means for increasing the inverter loss A heat generation prevention control device for a motor.

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