JP4760318B2 - Electric motor control device - Google Patents

Description

  The present invention relates to a motor control device, and more particularly to a control device that performs drive control of a motor supplied with power from a power source via a power converter.

  Conventionally, a power converter such as an inverter is used to convert electric power from a power source and supply it to an electric motor. The power converter generally performs power conversion by the switching operation of the switching element. However, since the switching element generates heat with the switching operation, it is necessary to suppress overheating of the switching element. For example, in Patent Document 1 below, when the switching element temperature of the power converter is in a high temperature state and the time change rate of the element temperature is large, the motor torque command is set small accordingly. By reducing the motor torque by this setting, the amount of heat generated by the switching element is reduced and overheating of the switching element is suppressed.

  In addition, the control apparatus of the electric motor by the following patent documents 2 and 3 is disclosed.

JP-A-10-210790 JP 2003-274509 A JP 2005-20891 A

  In order to more effectively use the torque of the electric motor while suppressing overheating of the power converter, it is desirable that the electric motor can output a large torque for a longer time within a range where the power converter does not overheat. In Patent Document 1, the torque of the motor is adjusted according to the switching element temperature so that the switching element does not overheat, but the allowable time for driving the motor in a state where the motor torque reaches the set upper limit value is adjusted. Nothing is shown about adjusting the time reduction rate when reducing the motor torque from the set upper limit value.

  An object of the present invention is to provide an electric motor control device that can output a large torque for a longer time while suppressing overheating of a power converter.

  The motor control device according to the present invention employs the following means in order to achieve the above-described object.

The motor control device according to the present invention is a control used in an electric motor drive device having an electric motor to which electric power from a power source is supplied via a power converter, and a cooler that cools the power converter with a refrigerant. A refrigerant temperature detection unit that detects the temperature of the refrigerant, a drive control unit that drives and controls the electric motor so that the torque of the electric motor does not exceed a set upper limit value, and the torque of the electric motor is approximately equal to the upper limit value. A permissible time setting unit that sets a permissible time for driving the electric motor in a state in which the motors match, and the drive control unit includes a motor when the state in which the torque of the motor substantially matches the upper limit value exceeds the permissible time. drives and controls the motor to reduce the torque of the permissible time setting unit alters the allowable time according to the temperature of the refrigerant detected by the refrigerant temperature detecting unit, the drive control unit, a torque of the motor before If the condition in which substantially coincides with the upper limit value exceeds the allowable time, and summarized in that a time reduction rate is varied in accordance with the temperature of the refrigerant detected by the refrigerant temperature detecting portion when reducing the torque of the electric motor To do.

According to the present invention, by changing the allowable time for driving the motor in a state where the torque of the motor substantially matches the set upper limit value according to the temperature of the refrigerant that cools the power converter, the power converter As long as the motor does not overheat, the motor can output the upper limit torque for a longer time. Therefore, the electric motor can output a large torque for a long time while suppressing overheating of the power converter. Further, according to the present invention, the drive control unit determines the time decrease rate when the motor torque is decreased when the state where the torque of the motor substantially matches the upper limit exceeds the allowable time, the refrigerant temperature By changing the temperature according to the temperature of the refrigerant detected by the detection unit, it is possible to minimize the decrease in the torque of the motor within a range where the power converter does not overheat.

  In one aspect of the present invention, it is preferable that the permissible time setting unit increases the permissible time with respect to a decrease in the refrigerant temperature detected by the refrigerant temperature detection unit.

In one aspect of the present invention, the drive motion control unit, if the state in which the torque of the motor is substantially equal to said upper limit value exceeds the allowable time, the time rate of decrease when decreasing the torque of the electric motor, the refrigerant temperature It is preferable to reduce the temperature of the refrigerant detected by the detection unit.

  The motor control device according to the present invention is used in an electric motor drive device having an electric motor to which electric power from a power source is supplied via a power converter, and a cooler that cools the power converter with a refrigerant. A refrigerant temperature detection unit that detects the temperature of the refrigerant, and a drive control unit that drives and controls the electric motor so that the torque of the electric motor does not exceed a set upper limit value. When the state in which the torque of the motor substantially matches the upper limit value exceeds the set time, the motor is driven and controlled so as to decrease the torque of the motor, and the time reduction rate of the torque of the motor is detected by the refrigerant temperature detection unit. The gist is to change the temperature according to the detected temperature of the refrigerant.

  According to the present invention, when the state in which the torque of the motor substantially matches the set upper limit value exceeds the set time, the time reduction rate when the motor torque is reduced is set to the refrigerant that cools the power converter. By changing according to the temperature of the motor, the reduction in the torque of the motor can be minimized as long as the power converter does not overheat. Therefore, the electric motor can output a large torque for a long time while suppressing overheating of the power converter.

  In one aspect of the present invention, the drive control unit is a refrigerant in which the time decrease rate of the motor torque is detected by the refrigerant temperature detection unit when a state in which the motor torque substantially matches the upper limit value exceeds a set time. It is preferable to decrease the temperature with respect to the decrease in temperature.

  In one aspect of the present invention, it is preferable to include a torque upper limit setting unit that changes the upper limit value according to the temperature of the refrigerant detected by the refrigerant temperature detection unit.

  In one embodiment of the present invention, the power converter is preferably an inverter.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention (hereinafter referred to as embodiments) will be described with reference to the drawings.

  FIG. 1 is a diagram showing a schematic configuration of a drive system for a hybrid vehicle including an electric motor control device according to an embodiment of the present invention. The control device according to the present embodiment is used in an electric motor drive device having a motor (electric motor) 10, an inverter 12, and a cooler 18 described below, and performs drive control of the motor 10.

  An output shaft of the engine (internal combustion engine) 50 is connected to a power distribution mechanism 52. The power distribution mechanism 52 is connected to the input shaft of the speed reducer 14 and the rotor of the generator (generator) 54 in addition to the output shaft of the engine 50. Here, the power distribution mechanism 52 can be constituted by, for example, a planetary gear mechanism having a ring gear, a carrier, and a sun gear. The output shaft of the speed reducer 14 is connected to the drive wheels 19. The power distribution mechanism 52 distributes the power from the engine 50 to the drive wheels 19 and the generator 54. The power distributed from the power distribution mechanism 52 to the generator 54 is converted into power generated by the generator 54. The electric power generated by the generator 54 can be supplied to the motor 10 via the inverter 12. Further, the electric power generated by the generator 54 can be recovered to the battery 16 via the inverter 12.

  The electric power from the battery 16 provided as a DC power source is supplied to the windings of the motor 10 after being converted by the inverter 12 provided as a power converter (DC to AC). The motor 10 converts the electric power supplied to the windings via the inverter 12 into the power of the rotor. The rotor of the motor 10 is connected to the input shaft of the speed reducer 14, and the power of the motor 10 is transmitted to the drive wheels 19 after being decelerated by the speed reducer 14. As described above, in the drive system according to the present embodiment, the power transmitted from the engine 50 to the drive wheels 19 via the power distribution mechanism 52 and the speed reducer 14 and the power from the motor 10 to the drive wheels 19 via the speed reducer 14. The drive wheel 19 can be driven to rotate (drive the vehicle) by using the transmitted power.

  In the inverter 12, power conversion is performed in which the DC power from the battery 16 is converted into AC and supplied to the motor 10 by the switching operation of the switching element. At that time, the inverter 12, particularly the switching element, generates heat. In the present embodiment, in order to suppress overheating of the inverter 12, a cooler 18 that cools the inverter 12 (particularly the switching element) with a coolant (refrigerant) is provided. And the temperature sensor 20 which detects the temperature T of the cooling fluid of the cooler 18 is also provided. The temperature T of the coolant detected by the temperature sensor 20 is input to the electronic control unit 30.

  The electronic control unit 30 controls the operation state of the motor 10 and the generator 54 by controlling the switching operation of the switching element of the inverter 12 based on, for example, the accelerator opening and the vehicle speed (both detected by a sensor not shown). . As shown in FIG. 2, the electronic control unit 30 includes a torque upper limit setting unit 32, a drive control unit 34, an allowable time setting unit 36, and a characteristic storage unit 38 which will be described below.

  The torque upper limit setting unit 32 sets the upper limit value τmax of the torque of the motor 10. Here, the upper limit value τmax of the torque of the motor 10 to be set is changed according to the coolant temperature T detected by the temperature sensor 20. For example, as shown in FIG. 3, a torque upper limit characteristic map representing the relationship between the coolant temperature T and the torque upper limit value τmax is stored in the characteristic storage unit 38, and the torque upper limit setting unit 32 stores the characteristic storage. The torque upper limit value τmax corresponding to the coolant temperature T detected by the temperature sensor 20 is set in the torque upper limit characteristic map read from the unit 38. In the torque upper limit characteristic map shown in FIG. 3, the torque upper limit value τmax increases as the coolant temperature T decreases. Therefore, the torque upper limit setting unit 32 sets the torque upper limit value τmax of the motor 10 to be set. Is increased with respect to a decrease in the temperature T of the coolant detected by the temperature sensor 20.

  The drive control unit 34 sets the target torque τ0 of the motor 10 based on, for example, the accelerator opening and the vehicle speed, and controls the switching operation of the inverter 12 so that the torque τ of the motor 10 matches the target torque τ0. 10 is driven and controlled. Here, by limiting the target torque τ0 of the motor 10 so as not to exceed the upper limit value τmax set by the torque upper limit setting unit 32, the torque τ of the motor 10 does not exceed the upper limit value τmax (upper limit The drive control of the motor 10 is performed (so as to be limited to the value τmax or less).

  The allowable time setting unit 36 sets an allowable time t1 at which the target torque τ0 of the motor 10 continues to be the upper limit value τmax set by the torque upper value setting unit 32 (or substantially becomes the upper limit value τmax). That is, the permissible time setting unit 36 sets the permissible time t1 for driving the motor 10 in a state where the torque τ of the motor 10 continuously matches (or substantially matches) the upper limit value τmax. Here, the allowable time t1 to be set is changed according to the temperature T of the coolant detected by the temperature sensor 20. For example, as shown in FIG. 4, an allowable time characteristic map representing the relationship between the coolant temperature T and the allowable time t1 is stored in the characteristic storage unit 38, and the allowable time setting unit 36 reads out from the characteristic storage unit 38. In the allowable time characteristic map, an allowable time t1 corresponding to the coolant temperature T detected by the temperature sensor 20 is set. In the allowable time characteristic map shown in FIG. 4, since the allowable time t1 increases as the coolant temperature T decreases, the allowable time setting unit 36 detects the allowable time t1 to be set by the temperature sensor 20. Increase with respect to decrease in temperature T of the coolant.

  Then, when the target torque τ0 of the motor 10 continues to become the upper limit value τmax (or almost reaches the upper limit value τmax), the drive control unit 34 exceeds the allowable time t1 set by the allowable time setting unit 36. Further, the target torque τ0 of the motor 10 to be set is decreased from the upper limit value τmax to the set value τ1. That is, when the torque τ of the motor 10 continues to coincide with (or substantially coincides with) the upper limit value τmax, the drive control unit 34 increases the torque τ of the motor 10 from the upper limit value τmax. The motor 10 is driven and controlled so as to decrease to the set value τ1. Here, the time decrease rate δτ / δt when the torque τ (target torque τ 0) of the motor 10 is decreased from the upper limit value τmax to the set value τ 1 changes according to the coolant temperature T detected by the temperature sensor 20. Let For example, as shown in FIG. 5, a torque reduction rate characteristic map representing the relationship between the coolant temperature T and the torque reduction rate δτ / δt is stored in the characteristic storage unit 38, and the drive control unit 34 In the torque reduction rate characteristic map read from the storage unit 38, a torque reduction rate δτ / δt corresponding to the coolant temperature T detected by the temperature sensor 20 is set. In the allowable time characteristic map shown in FIG. 5, since the time reduction rate δτ / δt of the torque decreases as the coolant temperature T decreases, the drive control unit 34 determines the torque τ (target torque τ0) of the motor 10. The time decrease rate δτ / δt when decreasing the upper limit value τmax from the upper limit value τmax to the set value τ1 is decreased with respect to the decrease in the coolant temperature T detected by the temperature sensor 20. Here, the direction in which the time during which the torque τ of the motor 10 decreases to the set value τ1 becomes shorter is the direction in which the time decrease rate δτ / δt increases.

  For example, when the vehicle is going uphill, the traveling load of the vehicle (the driving load of the motor 10) increases, so that the torque generated by the motor 10, that is, the current flowing through the motor 10 increases, so that the switching element of the inverter 12 generates heat. It becomes easy to do. In order to suppress overheating of the switching element, it is required to suppress the torque generated by the motor 10 (current flowing through the motor 10). However, on the other hand, in order to ensure the climbing performance of the vehicle, the motor 10 is also required to output a large torque.

  In the present embodiment, as shown in FIG. 6, when the torque τ of the motor 10 increases and reaches the upper limit value τmax (time t <b> 2 in FIG. 6) when the vehicle is climbing, the torque τ of the motor 10 is the upper limit. Limited to the value τmax. The upper limit value τmax here changes in accordance with the temperature T of the coolant, and increases as the temperature T of the coolant decreases. As shown in FIG. 6, when it is determined that the state where the torque τ of the motor 10 reaches the upper limit value τmax exceeds the allowable time t1 (time t3 in FIG. 6), the torque τ of the motor 10 is changed to the upper limit value τmax. To the set value τ1. The allowable time t1 here changes according to the temperature T of the coolant, and increases as the temperature T of the coolant decreases. Therefore, when the temperature T of the coolant is low, the motor 10 can output the torque τ having the upper limit value τmax for a long time without causing the inverter 12 to overheat. On the other hand, when the temperature T of the coolant is high, the time during which the motor 10 outputs the torque τ having the upper limit value τmax is shortened, so that overheating of the inverter 12 is suppressed. As the coolant temperature T used for setting the allowable time t1, for example, the coolant temperature T detected by the temperature sensor 20 at time t2 in FIG. 6 can be used.

  As described above, in this embodiment, the allowable time t1 for driving the motor 10 in a state where the torque τ of the motor 10 reaches the upper limit value τmax is changed in accordance with the coolant temperature T, so that the inverter 12 is not overheated. Thus, the motor 10 can output the torque τ having the upper limit value τmax for a long time. Therefore, the motor 10 can output a large torque for a longer time while suppressing overheating of the inverter 12.

  In this embodiment, when the state where the torque τ of the motor 10 reaches the upper limit value τmax exceeds the allowable time t1, the time reduction rate when the torque τ of the motor 10 is decreased from the upper limit value τmax to the set value τ1. δτ / δt changes according to the coolant temperature T, and decreases as the coolant temperature T decreases. Therefore, when the temperature T of the coolant is low, the decrease in the torque τ of the motor 10 can be suppressed to a necessary minimum within a range where the inverter 12 does not overheat, and the motor 10 can output a large torque for a long time. On the other hand, when the temperature T of the coolant is high, the temperature τ of the motor 10 (the temperature of the inverter 12) can be quickly reduced by quickly reducing the torque τ of the motor 10, and the overheating of the inverter 12 can be reduced. Can be deterred. Therefore, according to the present embodiment, the motor 10 can output a large torque for a longer time while suppressing overheating of the inverter 12. As the coolant temperature T used for setting the time decrease rate δτ / δt, for example, the coolant temperature T detected by the temperature sensor 20 at time t3 in FIG. 6 can be used.

  Thus, in this embodiment, the torque τ of the motor 10 can be used more effectively while suppressing overheating of the inverter 12. As a result, the climbing performance of the vehicle can be ensured while preventing overheating of the inverter 12 when the vehicle is climbing.

  Further, in the present embodiment, overheating of the inverter 12 can also be suppressed by changing the upper limit value τmax of the torque of the motor 10 according to the temperature T of the coolant.

  In the above description, the present invention is applied to a hybrid vehicle equipped with the engine 50 and the motor 10 as a power generation source. However, the present invention can also be applied to an electric vehicle equipped with the motor 10 as a power generation source. it can. Furthermore, the present invention can be applied to drive systems other than vehicles.

  As mentioned above, although the form for implementing this invention was demonstrated, this invention is not limited to such embodiment at all, and it can implement with a various form in the range which does not deviate from the summary of this invention. Of course.

It is a figure which shows schematic structure of the drive system of the hybrid vehicle containing the control apparatus of the electric motor which concerns on embodiment of this invention. It is a block diagram which shows schematic structure of the control apparatus of the electric motor which concerns on embodiment of this invention. It is a figure which shows an example of the torque upper limit characteristic map showing the relationship between the temperature T of a cooling fluid, and the upper limit value (tau) max of a torque. It is a figure which shows an example of the allowable time characteristic map showing the relationship between the temperature T of a cooling fluid, and allowable time t1. It is a figure which shows an example of the torque reduction rate characteristic map showing the relationship between the temperature T of a cooling fluid, and the time reduction rate (delta) (tau) / delta t of a torque. It is a figure explaining operation | movement of the control apparatus of the electric motor which concerns on embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Motor (electric motor), 12 Inverter, 14 Reducer, 16 Battery, 18 Cooler, 19 Drive wheel, 20 Temperature sensor, 30 Electronic control unit, 32 Torque upper limit value setting part, 34 Drive control part, 36 Allowable time setting part , 38 characteristic storage unit, 50 engine (internal combustion engine), 52 power distribution mechanism, 54 generator (generator).

Claims (7)

A control device used in an electric motor drive device having an electric motor supplied with electric power from a power source via a power converter and a cooler that cools the power converter with a refrigerant,
A refrigerant temperature detector for detecting the temperature of the refrigerant;
A drive control unit that drives and controls the electric motor so that the torque of the electric motor does not exceed the set upper limit value;
An allowable time setting unit for setting an allowable time for driving the electric motor in a state where the torque of the electric motor substantially matches the upper limit value;
With
The drive control unit drives and controls the motor so as to decrease the torque of the motor when the state in which the torque of the motor substantially matches the upper limit exceeds the allowable time.
The allowable time setting unit changes the allowable time according to the temperature of the refrigerant detected by the refrigerant temperature detection unit ,
When the state in which the torque of the motor substantially matches the upper limit value exceeds the allowable time, the drive control unit determines the rate of time reduction when the motor torque is decreased by the refrigerant temperature detected by the refrigerant temperature detection unit. A control device for an electric motor, which is changed according to temperature . The motor control device according to claim 1,
The permissible time setting unit increases the permissible time with respect to a decrease in the refrigerant temperature detected by the refrigerant temperature detection unit. A control device for an electric motor according to claim 1 or 2,
When the state in which the torque of the motor substantially matches the upper limit value exceeds the allowable time, the drive control unit determines the rate of time reduction when the motor torque is decreased by the refrigerant temperature detected by the refrigerant temperature detection unit. A control device for an electric motor, wherein the control device reduces the temperature in response to a decrease in temperature. A control device used in an electric motor drive device having an electric motor supplied with electric power from a power source via a power converter and a cooler that cools the power converter with a refrigerant ,
A refrigerant temperature detector for detecting the temperature of the refrigerant;
A drive control unit that drives and controls the electric motor so that the torque of the electric motor does not exceed the set upper limit value;
With
The drive control unit controls the drive of the motor so as to decrease the torque of the motor when the state where the torque of the motor substantially matches the upper limit value exceeds the set time, and reduces the time reduction rate of the motor torque. A control device for an electric motor that changes the temperature according to the temperature of the refrigerant detected by the medium temperature detection unit. The motor control device according to claim 4 ,
Drive control unit, when the state in which the torque of the motor is substantially equal to said upper limit value exceeds a set time, a time reduction rate of the torque of the electric motive to decrease the temperature of the refrigerant detected by the refrigerant temperature detecting unit The motor control device is characterized in that it is reduced . The electric motor control device according to any one of claims 1 to 5 ,
An electric motor control device comprising: a torque upper value setting unit that changes the upper limit value in accordance with a refrigerant temperature detected by a refrigerant temperature detection unit . A control device for an electric motor according to any one of claims 1 to 6,
The electric power converter is an inverter .

Images