JP2010269714A - Torque controller of electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque controller capable of setting appropriate torque according to the revolution speed of an electronic motor within the range of power which can be output by a capacitor. <P>SOLUTION: A torque controller of an electric motor includes: a revolution speed acquisition part for acquiring the revolution speed of an electric motor; a revolution speed correction part for correcting the revolution speed acquired by the revolution speed acquisition part; a request torque calculation part for calculating the request torque of the electric motor required for enabling the revolution speed of the electric motor to reach target revolution speed based on the revolution speed corrected by the revolution speed correction part according to the start state of an internal combustion engine; and a torque restriction value calculation part for calculating the torque restriction value of the electric motor based on the revolution speed corrected by the revolution speed correction part according to the start state of the internal combustion engine. The revolution speed correction part corrects the revolution speed acquired by the revolution speed acquisition part according to a time delay since the revolution speed is acquired by the revolution speed acquisition part until the torque restriction value is calculated by the request torque value calculation part, and when the request torque exceeds the torque restriction value, the electric motor is driven based on the torque restriction value. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a torque control device for an electric motor.

  Conventionally, in a hybrid vehicle, when the internal combustion engine is started, the output shaft of the internal combustion engine is cranked by an electric motor driven by a capacitor to increase the rotational speed. It is known that the cranking torque for cranking the output shaft is obtained from, for example, the maximum power that can be output by the battery, the energy loss during cranking, and the rotational speed of the output shaft of the internal combustion engine. (For example, refer to Patent Document 1).

JP-A-2005-180230

  According to Patent Document 1, it is possible to calculate the cranking torque according to the rotational speed. However, the part that controls the electric motor and the part that controls the internal combustion engine may be separated from each other. In this case, for example, communication is performed between the part for acquiring the rotation speed and the part for calculating the cranking torque, and there is a possibility that a time delay due to the communication occurs. If this time delay causes an error between the acquired number of revolutions and the number of revolutions at the time of calculating the cranking torque, there is a possibility of instructing the cranking torque exceeding the allowable power of the battery. is there.

  In order to avoid such a situation, conventionally, control for preparing an instruction for an excessive cranking torque due to an error in the rotational speed has been performed by estimating the capacity of the storage battery to be lower than the actual capacity. However, by estimating the capacity of the storage battery to be lower than the actual capacity, for example, the temperature at which the electric motor can be started by the storage battery is set higher than the actual capacity, so that it becomes impossible to start at a low temperature. . Therefore, it is desired to control the torque of the electric motor by the cranking torque calculated based on the rotation speed without error and to make maximum use of the capacity of the battery.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an electric motor capable of setting an appropriate torque in accordance with the number of rotations of the electric motor within the range of electric power that can be output from the battery. A torque control device is provided.

  In order to achieve the above object, the invention according to claim 1 is configured to rotate a crankshaft (for example, a crankshaft 109 in an embodiment described later) with electric power supplied from the capacitor (for example, a capacitor 101 in an embodiment described later). In a torque control device for an electric motor (for example, an electric motor 105 in an embodiment to be described later) capable of starting an internal combustion engine (for example, an internal combustion engine 107 in an embodiment to be described later), a rotational speed acquisition unit that acquires the rotational speed of the motor. (For example, a MOT rotation speed acquisition unit 121 in an embodiment described later) and a rotation speed correction unit that corrects the rotation speed acquired by the rotation speed acquisition unit (for example, a MOT rotation speed correction unit 131 in an embodiment described later). In the start state of the internal combustion engine, the rotational speed of the electric motor is set to a target based on the rotational speed corrected by the rotational speed correction unit. A required torque calculation unit (for example, a required torque calculation unit 133 in an embodiment described later) for calculating the required torque of the electric motor required to reach the rotation number, and in the starting state of the internal combustion engine, the rotation speed correction unit A torque limit value calculation unit (for example, a torque limit value calculation unit 135 in an embodiment described later) that calculates a torque limit value of the electric motor based on the corrected rotation number, and the rotation number correction unit includes the When the rotational speed acquired by the rotational speed acquisition unit is corrected according to the time delay from the acquisition by the rotational speed acquisition unit to the calculation by the required torque calculation unit, and the required torque exceeds the torque limit value The motor is driven based on the torque limit value.

  According to a second aspect of the present invention, in the torque control apparatus for an electric motor according to the first aspect, a starting state determination unit that determines whether or not the internal combustion engine is in a starting state (for example, a starting state determination in an embodiment described later). 139) and a rotation angle acquisition unit that acquires the rotation angle of the crankshaft (for example, a crank rotation angle acquisition unit 141 in an embodiment described later), and it is determined that the internal combustion engine is in a starting state The torque limit value calculation unit calculates a torque limit value based on the rotation speed corrected by the rotation speed correction unit, and when it is determined that the internal combustion engine is not in a start state, the torque limit value calculation unit The torque limit value is calculated based on the rotation angle acquired by the rotation angle acquisition unit.

  According to a third aspect of the present invention, in the torque control apparatus for an electric motor according to the first aspect, a start state determination unit that determines whether or not the internal combustion engine is in a start state, and the internal combustion engine is in a start state When it is determined, the torque limit value calculation unit calculates a torque limit value based on the rotation speed corrected by the rotation speed correction unit, and when it is determined that the internal combustion engine is not in a start state, the torque limit value The calculation unit calculates a torque limit value based on the rotation speed acquired by the rotation speed acquisition unit.

  According to a fourth aspect of the present invention, there is provided a torque control device for an electric motor capable of starting an internal combustion engine by rotating a crankshaft by electric power supplied from a capacitor, and a rotation speed acquisition unit that acquires the rotation speed of the electric motor; A rotation speed correction section that corrects the rotation speed acquired by the number acquisition section; a torque limit value calculation section that calculates a torque limit value of the electric motor based on the rotation speed acquired by the rotation speed acquisition section; and the internal combustion engine A request torque calculation unit that calculates a required torque of the motor required for the rotation speed of the electric motor to reach a target rotation speed based on the rotation speed corrected by the rotation speed correction unit in an engine start state; The rotational speed correction unit corrects the rotational speed acquired by the rotational speed acquisition unit according to a time delay from acquisition of the rotational speed to calculation of the required torque, and the request When the torque exceeds the torque limit value, and drives the motor based on the torque limit value.

  According to a fifth aspect of the present invention, in the torque control apparatus for an electric motor according to any one of the first to fourth aspects, the time delay is caused by communication between the rotation speed acquisition unit and the required torque calculation unit. It is characterized by.

  According to a sixth aspect of the present invention, in the motor torque control apparatus according to any one of the first to fourth aspects, the time delay is obtained by processing timings of acquisition by the rotational speed acquisition unit and calculation by the required torque calculation unit. It is caused by a difference.

  According to the first aspect of the present invention, in the starting state of the internal combustion engine, the required torque and the torque limit value are calculated based on the rotation speed corrected by the rotation speed correction unit, so that the torque can be set appropriately. . Further, when the required torque exceeds the torque limit value, the electric motor is driven based on the torque limit value, so that the control can be performed within the output power range of the battery.

  According to the second and third aspects of the present invention, it is possible to appropriately set the torque according to the rotation speed of the electric motor in the starting state of the internal combustion engine in which the increase of the rotation speed of the electric motor during the predetermined time is particularly large.

  According to the fourth aspect of the present invention, the required torque is calculated based on the rotation speed corrected by the rotation speed correction unit, so that the torque can be set appropriately. Further, when the required torque exceeds the torque limit value, the electric motor is driven based on the torque limit value, so that the control can be performed within the output power range of the battery.

  According to the invention of claim 5, even when the rotation speed acquisition unit and the required torque calculation unit are provided in separate ECUs, and communication is performed between the rotation speed acquisition unit and the required torque calculation unit. The torque can be set appropriately.

  According to the sixth aspect of the present invention, torque can be set appropriately even when the processing timing of the rotation speed acquisition unit and the processing timing of the required torque calculation unit are different.

It is a block diagram which shows the torque control apparatus of the electric motor concerning 1st Embodiment. It is a flowchart which shows operation | movement of the torque control apparatus of the electric motor concerning 1st Embodiment. It is a flowchart which shows the operation | movement of the rotation speed correction | amendment by a rotation speed correction | amendment part. It is a graph which shows the rotation speed correct | amended by 1st Embodiment, and the request torque calculated based on this compared with the conventional case which does not correct | amend. It is a graph which shows the power consumption of the electrical storage device by the torque set by 1st Embodiment compared with the conventional case which does not correct | amend rotation speed. It is a block diagram which shows the torque control apparatus of the electric motor concerning a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.

(First embodiment)
An electric motor torque control apparatus according to a first embodiment of the present invention will be described below with reference to FIGS. The vehicle of the present embodiment is a HEV (Hybrid Electrical Vehicle), and the vehicle travels by the driving force of an electric motor and / or an internal combustion engine.

  FIG. 1 is a block diagram illustrating an example of the configuration of a torque control device for an electric motor according to the present embodiment. In FIG. 1, a vehicle 1 includes a battery (BATT) 101, an electric motor (MOT) 105, an internal combustion engine (ENG) 107, a motor ECU (MOT ECU) 117, and an engine ECU (ENG ECU) 119. Part or the whole of the vehicle 1 functions as a torque control device for the electric motor.

  The storage battery 101 has a plurality of storage cells connected in series, and supplies a high voltage of, for example, 100 to 200V. Output power from the battery 101 is supplied to the electric motor 105 to drive the electric motor 105.

  The electric motor 105 is a generator motor, for example, and rotates the crankshaft 109 with the output power of the battery 101 to start the internal combustion engine 107. Further, the electric motor 20 is driven based on the torque command value from the MOT rotation control unit 123 of the motor ECU 117, so that the vehicle 1 performs electric running. A signal indicating the rotation speed of the electric motor 105 detected by the MOT rotation speed sensor 111 is sent to the MOT rotation speed acquisition unit 121 of the motor ECU 117.

  The internal combustion engine 107 operates as a prime mover, and is started by the electric motor 105 according to the start switch 116. The internal combustion engine 107 generates power (torque) for running the vehicle by burning the fuel injected and supplied from the injector in response to the fuel injection command and the ignition command from the ENG rotation control unit 141. A rotating shaft (not shown) of the electric motor 105 and the crankshaft 109 of the internal combustion engine 107 are directly connected. Torque generated in the internal combustion engine 107 is transmitted to a drive shaft of a drive wheel (not shown) via a crankshaft 109. The rotation angle of the crankshaft 109 is detected for each predetermined angle by the crank rotation angle sensor 113. A signal indicating the crank rotation angle detected by the crank rotation angle sensor 113 is sent to the crank rotation angle acquisition unit 141 of the engine ECU 119.

  The motor ECU 117 controls the electric motor 105 and includes a MOT rotation speed acquisition unit 121 and a MOT rotation control unit 123. The MOT rotation speed acquisition unit 121 acquires the rotation speed of the electric motor 105 from the rotation speed sensor signal sent from the MOT rotation speed sensor 111 and sends it to the MOT rotation speed correction section 131 of the engine ECU 119. MOT rotation control unit 123 controls electric motor 105 based on the final torque value sent from final torque value setting unit 137 of engine ECU 119.

  The engine ECU 119 controls the internal combustion engine 107, and includes a MOT rotation speed correction unit 131, a required torque calculation unit 133, a torque limit value calculation unit 135, a final torque value setting unit 137, and a starting state determination unit 139. And a crank rotation angle acquisition unit 141 and an ENG rotation control unit 143.

  The MOT rotation speed correction unit 131 corrects the rotation speed acquired by the MOT rotation speed acquisition unit 121 based on the previous final torque value and the time delay. The required torque calculation unit 133 calculates the required torque based on the rotation speed corrected by the MOT rotation speed correction unit 131 and the accelerator signal 115. The torque limit value calculation unit 135 calculates a torque limit value based on the rotation number corrected by the MOT rotation number correction unit 131 and the crank rotation angle acquired by the crank rotation angle acquisition unit 141. The final torque value setting unit 137 sets a final torque value for controlling the electric motor 105. The starting state determination unit 139 determines whether or not the internal combustion engine 107 is in a starting state based on the start switch 116 and the crank rotation angle. The ENG rotation control unit 143 controls the opening / closing control of the throttle valve and the fuel injection control and the rotation speed of the crankshaft 109 in each cylinder.

  Hereinafter, the operation of the torque control apparatus for an electric motor according to the present embodiment will be described in detail. FIG. 2 is a flowchart showing the operation of the motor torque control apparatus according to the present embodiment. As shown in FIG. 2, first, the starting state determination unit 139 determines whether or not the internal combustion engine is in a starting state (step S1). Here, the start state of the internal combustion engine is a state from when the start switch (ignition switch) 116 is turned on until the rotation speed of the crankshaft increases to the target rotation speed. Therefore, the starting state determination unit 139 determines whether the internal combustion engine 107 is in a starting state based on the state of the start switch 116 and the crank rotation angle acquired by the crank rotation angle acquisition unit 141.

  When it is determined that the internal combustion engine 107 is in the starting state, the MOT rotation speed acquisition unit 121 acquires the rotation speed of the electric motor 105 from the rotation speed sensor signal of the MOT rotation speed sensor 111 (step S2). In the present embodiment, since the rotation shaft (not shown) of the electric motor 105 and the crankshaft 109 of the internal combustion engine 107 are directly connected, the rotation speed of the electric motor 105 is equal to the rotation speed of the crankshaft 109 of the internal combustion engine 107. The rotation speed of the electric motor 105 acquired by the MOT rotation speed acquisition unit 121 is sent to the MOT rotation speed correction unit 131.

  In the present embodiment, the MOT rotation speed acquisition unit 121 is provided in the motor ECU 117, whereas the required torque calculation unit 133 and the torque limit value calculation unit 135 are provided in the engine ECU 119. For this reason, the rotation speed of the electric motor 105 acquired by the MOT rotation speed acquisition unit 121 is sent to the engine ECU 119 by communication. Depending on the communication status and processing timing, there will be a time lag from the acquisition of the rotational speed to the calculation of the required torque and torque limit value, and the acquired rotational speed and the rotational speed at the time of calculation will be An error occurs in the meantime. In particular, in the starting state of the internal combustion engine in which the rotational speed reaches 0 to the target rotational speed, the degree of increase in the rotational speed is large, so that an error caused by a time delay is large. In order to avoid the occurrence of such an error, in the present embodiment, the MOT rotation number correction unit 131 corrects the rotation number acquired by the MOT rotation number acquisition unit 121 (step S3).

  FIG. 3 is a flowchart for explaining the operation for correcting the rotational speed. First, the MOT rotation number correction unit 131 acquires the MOT rotation number Ndet from the MOT rotation number acquisition unit 121 (step S21). Next, the MOT rotation speed correction unit 131 divides the previous value of the final torque, which is the torque that is currently driving the electric motor 105, by the inertia and multiplies the time delay due to communication, thereby increasing the time delayed by communication. The rotation speed Nadj is calculated (step S22). Here, the inertia is the ease of rotation due to the inertia of the rotor of the electric motor 105, and is a value that is determined by design depending on the material and shape of the rotor of the electric motor 105. Finally, the MOT rotation speed correction unit 131 calculates the corrected rotation speed N by adding Nadj to the MOT rotation speed Ndet (step S23).

  Returning to FIG. 2, the required torque calculation unit 133 calculates the required torque required to make the rotation speed of the crankshaft 109 reach the target rotation speed based on the corrected rotation speed N (step S <b> 4). The torque limit value calculation unit 135 calculates a torque limit value based on the maximum output power of the battery 101 and the corrected rotation speed N (step S5).

  FIG. 4 is a graph showing the rotation speed corrected according to the present embodiment and the required torque calculated based on the rotation speed compared with the conventional case where no correction is performed. In the figure, Ndet indicates the rotational speed acquired by the MOT rotational speed acquisition unit 121 corresponding to the passage of time since the internal combustion engine 107 was started, and N is the rotational speed corrected by the MOT rotational speed correction unit 131. Indicates. Tdet indicates the required torque calculated based on Ndet, and T indicates the required torque calculated based on N. It can be seen from FIG. 4 that the required torque Tdet without correction is calculated to be larger than the required torque T with correction.

  If it is determined in step S1 that the internal combustion engine 107 is not in the starting state, the rotational speed of the crankshaft 109 has already increased to the target rotational speed. In such a case, the required torque is calculated in order to drive the vehicle according to the depression amount of the accelerator pedal. Therefore, the required torque calculation unit 133 calculates the required torque based on the accelerator signal 115 indicating the depression amount of the accelerator pedal (step S6).

  The torque limit value calculation unit 135 calculates a torque limit value based on the crank rotation angle acquired by the crank rotation angle acquisition unit 141 (step S7). Since the crank angle sensor 113 detects the rotation angle of the crankshaft 109 for each predetermined rotation angle, the rotation speed of the crankshaft 109 is small, and the degree of increase in the rotation speed within a predetermined time is high. In this case, an error may occur depending on the detection timing. However, after the rotation speed of the crankshaft 109 has increased to the target rotation speed, the crank angle sensor 113 can perform stable detection. In addition, the crank rotation angle acquisition unit 141 is provided in the engine ECU 119, and a time delay due to communication does not occur. Therefore, when it is determined that the internal combustion engine 107 is not in the starting state, the torque limit value is based on the crank rotation angle. Is calculated.

  After the request torque and the torque limit value are calculated by the request torque calculation unit 133 and the torque limit value calculation unit 135, the final torque value setting unit 137 determines whether or not the request torque ≦ the torque limit value (step S8). ). If the required torque ≦ the torque limit value, the required torque is set as the final torque value (step S9). On the other hand, if the required torque is greater than the torque limit value, the torque limit value is set as the final torque value (step S10). The final torque value setting unit 137 sends the set final torque value to the MOT rotation control unit 123 of the motor ECU 117 (step S11). The MOT rotation control unit 123 controls the electric motor 105 based on the final torque value. Since the final torque value is used at the next rotation speed correction, it is also sent to the MOT rotation speed correction unit 131.

  FIG. 5 is a graph showing the power consumption P of the battery by the torque set according to the present embodiment compared with the power consumption Pdet in the conventional case where no correction is performed. Pdet is power consumption when the electric motor is driven by the torque calculated based on the rotational speed in which an error occurs due to time delay, and exceeds the allowable output power of the battery 101. On the other hand, in the present embodiment, the required torque and the torque limit value are calculated based on the corrected rotational speed, and when the required torque exceeds the torque limit value, the electric motor 105 is driven by the torque limit value. It is within the allowable output power range of the battery 101.

  As described above, according to the torque control apparatus for an electric motor according to the present embodiment, correction is performed by the MOT rotation speed correction unit 131 in the start-up state of the internal combustion engine 107 in which the increase in the rotation speed of the electric motor 105 is particularly large during a predetermined time. Since the required torque and the torque limit value are calculated based on the rotation speed thus set, the torque can be set appropriately. Further, the MOT rotation speed acquisition unit 121, the required torque calculation unit 133, and the torque limit value calculation unit 135 are provided in different ECUs, respectively, and the MOT rotation speed acquisition unit 121, the required torque calculation unit 133, and the torque limit value calculation unit 135 are provided. Even when communication is performed between the requested torque and the torque limit value, the required torque and the torque limit value can be calculated appropriately. Further, when the required torque exceeds the torque limit value, the electric motor 105 is driven by the torque limit value, so that the control can be performed within the range of the output power of the battery 101.

  In the present embodiment, when it is determined that the internal combustion engine 107 is not in the starting state, the torque limit value is calculated based on the crank rotation angle acquired by the crank rotation angle acquisition unit 141. The torque limit value may be calculated based on the rotation speed acquired by the rotation speed acquisition unit 121. After the rotation speed of the crankshaft 109 rises to the target rotation speed and the internal combustion engine is not in the starting state, the rotation speed of the electric motor 105 does not vary so much, and the error due to time delay decreases. Therefore, when it is determined that the internal combustion engine 107 is not in the starting state, the torque limit value calculation unit 135 can appropriately calculate the torque limit value based on the rotation speed acquired by the MOT rotation speed acquisition unit 121. .

  In the present embodiment, the correction of the rotation speed by the MOT rotation speed correction unit 131 is performed only when the internal combustion engine 107 is in the start state, but it depends on whether or not the internal combustion engine 107 is in the start state. Instead, the torque limit value may be calculated based on the always corrected rotational speed.

(Modification)
FIG. 6 is a block diagram of an electric motor torque control device according to a modification of the present embodiment. The present modification is different from the first embodiment in the configuration of the torque limit value calculation unit 135 and the final torque value setting unit 137. The same or equivalent parts as those in the first embodiment are denoted by the same or corresponding reference numerals, and the description will be simplified or omitted.

  In the present modification, the torque limit value calculation unit 135 is provided in the motor ECU 117, so that no time delay is caused by communication with the MOT rotation speed acquisition unit 121 that is also provided in the motor ECU 117. Therefore, in the present modification, the torque limit value calculation unit 135 always sets the torque limit value based on the rotation speed acquired by the MOT rotation speed acquisition unit 121 regardless of whether the internal combustion engine 107 is in the starting state. calculate.

  In addition, this invention is not limited to embodiment mentioned above, A deformation | transformation, improvement, etc. are possible suitably. For example, the present invention is a case where the control of the electric motor 105 and the control of the internal combustion engine 107 are performed in one ECU, and the processing timing such as the acquisition cycle of the MOT rotation speed acquisition unit 121 and the required torque calculation unit 133 or The present invention can also be applied to a case where an error occurs in the rotational speed due to a time delay caused by the processing timing of the torque limit value calculation unit 135 being different.

101 Battery (BATT)
105 Electric motor (MOT)
107 Multi-cylinder internal combustion engine (ENG)
109 Crankshaft 117 Engine ECU (ENG ECU)
119 Motor ECU (MOT ECU)
121 MOT rotation speed acquisition section 131 MOT rotation speed correction section 133 Required torque calculation section 135 Torque limit value calculation section 139 Start state determination section 141 Crank rotation angle acquisition section

Claims (6)

In the torque control device for an electric motor that can start an internal combustion engine by rotating a crankshaft by electric power supplied from a capacitor,
A rotational speed acquisition unit for acquiring the rotational speed of the electric motor;
A rotational speed correction unit that corrects the rotational speed acquired by the rotational speed acquisition unit;
A required torque calculating unit that calculates a required torque of the electric motor required for the rotational speed of the electric motor to reach a target rotational speed based on the rotational speed corrected by the rotational speed correcting unit in a starting state of the internal combustion engine; ,
A torque limit value calculation unit that calculates a torque limit value of the electric motor based on the rotation speed corrected by the rotation speed correction unit in a start state of the internal combustion engine;
The rotation speed correction unit corrects the rotation speed acquired by the rotation speed acquisition unit according to a time delay from acquisition by the rotation speed acquisition unit to calculation by the required torque calculation unit,
When the required torque exceeds the torque limit value, the motor is driven based on the torque limit value. A starting state determination unit for determining whether or not the internal combustion engine is in a starting state;
A rotation angle acquisition unit that acquires a rotation angle of the crankshaft,
When it is determined that the internal combustion engine is in a starting state, the torque limit value calculation unit calculates a torque limit value based on the rotation speed corrected by the rotation speed correction unit,
The torque limit value calculation unit calculates a torque limit value based on the rotation angle acquired by the rotation angle acquisition unit when it is determined that the internal combustion engine is not in a starting state. Motor torque control device. A starting state determination unit for determining whether or not the internal combustion engine is in a starting state;
When it is determined that the internal combustion engine is in a starting state, the torque limit value calculation unit calculates a torque limit value based on the rotation speed corrected by the rotation speed correction unit,
The torque limit value calculation unit calculates a torque limit value based on the rotation speed acquired by the rotation speed acquisition unit when it is determined that the internal combustion engine is not in a starting state. Motor torque control device. In the torque control device for an electric motor that can start an internal combustion engine by rotating a crankshaft by electric power supplied from a capacitor,
A rotational speed acquisition unit for acquiring the rotational speed of the electric motor;
A rotational speed correction unit that corrects the rotational speed acquired by the rotational speed acquisition unit;
A torque limit value calculation unit that calculates a torque limit value of the electric motor based on the rotation number acquired by the rotation number acquisition unit;
A required torque calculating unit that calculates a required torque of the electric motor required for the rotational speed of the electric motor to reach a target rotational speed based on the rotational speed corrected by the rotational speed correcting unit in a start state of the internal combustion engine; With
The rotational speed correction unit corrects the rotational speed acquired by the rotational speed acquisition unit according to a time delay from acquisition by the rotational speed acquisition unit to calculation of the required torque,
When the required torque exceeds the torque limit value, the motor is driven based on the torque limit value.   5. The torque control apparatus for an electric motor according to claim 1, wherein the time delay is caused by communication between the rotation speed acquisition unit and the required torque calculation unit.   5. The torque control apparatus for an electric motor according to claim 1, wherein the time delay is caused by a difference in processing timing between acquisition by the rotation speed acquisition unit and calculation by the required torque calculation unit.

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