Motor drive device and control method thereof

Abstract

A motor drive device and its control method are provided to improve the torque control accuracy of an induction motor driven by indirect vector control. The motor drive device includes: an induction motor having a stator and a rotor, the rotor rotating by a rotating magnetic field generated in the stator; and a controller for: determining the resistance of the rotor based on the error between the command torque and the output torque of the induction motor and the temperature of the induction motor; and controlling the output of the induction motor based on the determined rotor resistance.

Description

Technical Field

[0001] This disclosure relates to a motor drive device and its control method, in order to improve the torque control accuracy of an induction motor driven by indirect vector control. Background Technology

[0002] An induction motor generates rotational force through the electromagnetic force of the induced current generated in the rotor by the rotating magnetic field of the stator. It can control the magnetic flux component current and the torque component current through a synchronous coordinate system rotating at the speed of the magnetic flux vector, thereby controlling the torque instantaneously.

[0003] This instantaneous torque control technology for induction motors can be called vector control. Based on the method of obtaining the flux angle, vector control can be divided into direct vector control and indirect vector control. Direct vector control obtains the flux angle directly by estimating the flux itself, while indirect vector control obtains the flux angle indirectly by obtaining the sliding angular velocity.

[0004] Unlike direct vector control, indirect vector control indirectly estimates the flux angle by using the sliding angular velocity, thereby controlling the motor torque. Therefore, accurately determining the sliding angular velocity is an important factor in improving torque control accuracy.

[0005] Here, the slip velocity is generated because the rotor in the induction motor always rotates slower than the synchronous speed of the rotating magnetic field, and can be obtained based on the ratio of rotor resistance to rotor inductance and the current reference on the synchronous reference frame.

[0006] The above description of the background technology is intended only to enhance the understanding of the background of this disclosure and should not be construed as an admission that it corresponds to prior art known to those skilled in the art. Summary of the Invention

[0007] Various aspects of this disclosure aim to provide a motor drive device and control method thereof, which can improve the torque control accuracy of an induction motor by estimating the value of a rotor resistance that changes in real time and performing indirect vector control.

[0008] An electric motor drive device according to various aspects of this disclosure includes: an induction motor having a stator and a rotor, the rotor rotating by a rotating magnetic field generated in the stator; and a controller for: determining the resistance of the rotor based on an error between a commanded torque and an output torque of the induction motor and the temperature of the induction motor; and controlling the output of the induction motor based on the determined resistance of the rotor.

[0009] For example, the controller can perform torque error control based on the temperature of the induction motor so that the output torque tracks the command torque, and can determine the rotor resistance based on the result of the torque error control.

[0010] For example, the controller can repeatedly perform torque error control until the error between the commanded torque and the output torque becomes less than or equal to a predetermined reference error, and the rotor resistance can be re-determined.

[0011] For example, the controller can perform torque error control based on a pre-determined control gain corresponding to the temperature and commanded torque of the induction motor.

[0012] For example, control gain can include proportional gain and integral gain for the error between commanded torque and output torque.

[0013] For example, the controller can perform torque error control by referring to a table that stores control gains corresponding to the temperature and commanded torque of the induction motor.

[0014] For example, the controller can correct the torque error control result by anti-windup against the error between the commanded torque and the output torque, and can determine the rotor resistance based on the corrected torque error control result.

[0015] For example, the temperature of an induction motor can be the temperature of the stator coils.

[0016] For example, the controller can determine the sliding angular velocity of the induction motor based on the rotor's resistance, and can control the output of the induction motor based on the determined sliding angular velocity.

[0017] For example, it may also include an inverter for driving an induction motor, wherein the controller can convert the stator current to a synchronous coordinate system based on the slip angular velocity, and the inverter can be controlled by pulse width modulation (PWM) control based on the converted current, thereby controlling the output of the induction motor.

[0018] To achieve the above-mentioned task, a method for controlling a motor drive device according to an exemplary embodiment of the present disclosure includes: a controller determining the resistance of a rotor based on the error between a command torque and an output torque of an induction motor and the temperature of the induction motor, the induction motor comprising a stator and a rotor, the rotor rotating by a rotating magnetic field generated in the stator; and the controller controlling the output of the induction motor based on the determined resistance of the rotor.

[0019] For example, determining the rotor resistance may include: the controller performing torque error control based on the temperature of the induction motor to make the output torque track the command torque; and determining the rotor resistance based on the result of the torque error control.

[0020] For example, determining the rotor resistance may include: the controller repeatedly performing torque error control until the error between the commanded torque and the output torque becomes less than or equal to a predetermined reference error, in order to redetermine the rotor resistance.

[0021] For example, determining the rotor resistance may include: the controller performing torque error control based on a pre-determined control gain corresponding to the temperature and commanded torque of the induction motor.

[0022] For example, control gain can include proportional gain and integral gain for the error between commanded torque and output torque.

[0023] For example, determining the rotor resistance may include: the controller performing torque error control by referring to a table that stores control gains corresponding to the temperature and commanded torque of the induction motor.

[0024] For example, determining the rotor resistance may include: the controller correcting the result of torque error control by anti-saturation against the error between the commanded torque and the output torque; and determining the rotor resistance based on the corrected result of torque error control.

[0025] For example, the temperature of an induction motor can be the temperature of the stator coils.

[0026] For example, controlling the output of an induction motor may include: the controller determining the sliding angular velocity of the induction motor based on the rotor's resistance; and controlling the output of the induction motor based on the determined sliding angular velocity.

[0027] For example, controlling the output of an induction motor may include: the controller converting the stator current to the synchronous coordinate system based on the sliding angular velocity; and controlling the inverter used to drive the induction motor by pulse width modulation control based on the converted current, thereby controlling the output of the induction motor.

[0028] According to the various exemplary embodiments of this disclosure described above, by determining the sliding angular velocity by the value of the rotor resistance changing in real time, the estimation accuracy of the flux angle can be improved during indirect vector control, and correspondingly, the accuracy of torque control can be improved.

[0029] Furthermore, with the improvement of torque control accuracy, the command torque tracking performance can be improved without the need for a separate torque correction process.

[0030] Furthermore, various exemplary embodiments of this disclosure can be implemented by adding logic to an existing controller, achieving the above effects without increasing the size and cost of a separate hardware configuration.

[0031] The effects obtained by this disclosure are not limited to those described above. Other effects not mentioned can be clearly understood by those skilled in the art from the following description. Attached Figure Description

[0032] Figure 1 This is a view showing the structure of a motor drive device according to an exemplary embodiment of the present disclosure.

[0033] Figure 2 This is a view illustrating an exemplary implementation of a motor drive device according to an exemplary embodiment of the present disclosure.

[0034] Figure 3 This is a view illustrating a method for determining rotor resistance according to an exemplary embodiment of the present disclosure.

[0035] Figure 4 This is a flowchart illustrating a method for controlling a motor drive device according to an exemplary embodiment of the present disclosure. Detailed Implementation

[0036] The specific structural or functional descriptions of exemplary embodiments of this disclosure are merely shown for the purpose of explaining exemplary embodiments of this disclosure, and exemplary embodiments of this disclosure may be implemented in various forms and should not be construed as limited to the exemplary embodiments described in this specification or application.

[0037] Various modifications and forms can be made to the exemplary embodiments of this disclosure, and therefore specific exemplary embodiments are illustrated in the accompanying drawings and will be described in detail in this specification. However, this is not intended to limit the exemplary embodiments according to the concepts of this disclosure to any particular form of disclosure, but should be understood to include all modifications, equivalents, or alternatives falling within the spirit and technical scope of this disclosure.

[0038] Unless otherwise defined, all terms used herein, including technical or scientific terms, shall have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Terms (e.g., those defined in common dictionaries) shall be understood to have a meaning consistent with the relevant technical context and shall not be construed as having an idealized or overly formalized meaning unless expressly defined herein.

[0039] The exemplary embodiments disclosed in this specification will be described in detail below with reference to the accompanying drawings, but the same or similar components will be referred to by the same reference numerals, and repeated descriptions thereof will be omitted.

[0040] In the following description of exemplary embodiments, the term "predetermined" means that the value of a parameter is predetermined when used in a process or algorithm. According to exemplary embodiments, the value of the parameter may be set at the beginning of the process or algorithm, or it may be set during the execution of the process or algorithm.

[0041] The component suffixes “module” and “unit” used in the following description are specified or used interchangeably for convenience in writing the specification only, and are not intended to give them different meanings or functions.

[0042] In describing the exemplary embodiments disclosed in this specification, detailed descriptions of related known technologies will be omitted when it is determined that such detailed descriptions may obscure the spirit of the exemplary embodiments disclosed in this specification. Furthermore, the accompanying drawings are intended only to facilitate an easy understanding of the exemplary embodiments disclosed in this specification, and the technical concepts disclosed herein are not limited to the drawings and should be understood to include all modifications, equivalents, and substitutions within the scope of the concepts and techniques of this disclosure.

[0043] Terms that include ordinal numbers (such as first and second) can be used to describe various components, but components are not limited by these terms. These terms are only used to distinguish one component from another.

[0044] When a component is said to be "connected" or "linked" to another component, it should be understood that it can be directly connected or linked to another component, but other components may exist in between. Conversely, when a component is said to be "directly connected" or "directly linked" to another component, it should be understood that no other components exist in between.

[0045] Unless the context clearly indicates otherwise, singular expressions may include plural expressions.

[0046] In this specification, terms such as “comprising” or “having” may be intended to specify the presence of features, numbers, steps, operations, components, parts or combinations thereof described in the specification, and should be understood to not exclude the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

[0047] Furthermore, the units or control units included in names such as motor control unit (MCU) and hybrid power control unit (HCU) may simply be terms widely used to name controllers that control specific functions of a vehicle, and may not represent general-purpose functional units.

[0048] The controller may include communication devices for communicating with other controllers or sensors to control the functions it is responsible for; memory for storing operating system or logic commands and input / output information; and one or more processors for performing necessary operations such as judgment, calculation, and decision-making to control the functions it is responsible for.

[0049] The motor drive device and control method of the present disclosure according to exemplary embodiments can determine the rotor resistance based on the temperature of the induction motor, and can perform indirect vector control by the slip angular velocity derived therefrom, thereby improving the accuracy of torque control.

[0050] In the following description, before describing the method of controlling a motor drive device according to exemplary embodiments of the present disclosure, reference will first be made to... Figure 1 Describe the configuration of the motor drive unit.

[0051] Figure 1 This is a simplified block diagram illustrating the configuration of a motor drive device according to an exemplary embodiment of the present disclosure.

[0052] Reference Figure 1 The motor drive device according to an exemplary embodiment of the present disclosure may include an induction motor 100, a controller 200, and an inverter 300. The motor drive device may include a... Figure 1 This can be achieved using more or fewer components as shown.

[0053] The induction motor 100 may have a stator and a rotor, the rotor rotating by a rotating magnetic field generated in the stator. The stator may include coils for generating the rotating magnetic field, and the rotor may rotate by the electromagnetic force of the induced current generated by the rotating magnetic field.

[0054] The controller 200 can control the output of the induction motor 100. Specifically, the controller 200 can determine the rotor resistance based on the error between the command torque and the output torque of the induction motor 100 and the temperature of the induction motor 100. Furthermore, the controller 200 can determine the sliding angular velocity of the induction motor 100 based on the determined rotor resistance, and can control the output of the motor 100 based on the determined sliding angular velocity.

[0055] Inverter 300 can drive induction motor 100, for example, by switching operations of switching elements (e.g., insulated gate bipolar transistors (IGBTs) and metal-oxide-semiconductor field-effect transistors (MOSFETs)). This switching operation can be controlled by controller 200, and controller 200 can control inverter 300 based on commanded torque, thereby controlling the output of induction motor 100.

[0056] The following will refer to Figure 2 and Figure 3 The specific details of the motor drive device according to exemplary embodiments of the present disclosure will be described in more detail.

[0057] Figure 2 This is a simplified block diagram illustrating an exemplary implementation of a motor drive device according to an exemplary embodiment of the present disclosure. Figure 3 This is a flowchart illustrating a method for determining rotor resistance according to an exemplary embodiment of the present disclosure.

[0058] First, refer to Figure 2The induction motor 100 according to the exemplary embodiments of this disclosure can be implemented as a three-phase AC motor, and the inverter 300 can be implemented as a pulse width modulation (PWM) inverter. Furthermore, the controller 200 may include a flux controller 201, a current command graph 202, a current controller 203, a first converter 204, a torque error controller 205, a first gain table 206, a second gain table 207, a sliding angular velocity determination unit 208, a rotational angular velocity determination unit 209, a flux angle determination unit 210, and a second converter 211.

[0059] The flux controller 201 can receive the DC voltage (V) input to the inverter 300. dc ) and the synchronous velocity (ω) of the rotating magnetic field e It can take λ as input and output the inverse magnetic flux (λ). -1 The current command diagram 202 can receive the output reverse magnetic flux (λ). -1 ) and command torque (T) e * It can take ) as input and output the corresponding d-axis current command (i ds * ) and q-axis current command (i qs * For example, according to an exemplary embodiment, the command torque (T) e * The input can be directly entered into controller 200, or it can be obtained from the connected upstream controller.

[0060] The current controller 203 can adjust the current according to the d-axis current command (i) of the synchronous coordinate system. ds * ) and q-axis current command (i qs * ), outputs the d-axis voltage command (voltage reference) of the synchronous coordinate system (V ds * ) and q-axis voltage command (V qs * The output d-axis voltage command (V) ds * ) and q-axis voltage command (V qs * It can be converted into a three-phase voltage command (V) by the first converter 204. an * V bn * V cn * Then you can input it into the inverter 300.

[0061] Inverter 300 can operate according to three-phase voltage commands (Van * V bn * V cn * The output voltage causes the three-phase current (i) to... as i bs i cs The induced current flows into the stator of the induction motor 100 to generate a rotating magnetic field. For example, the rotor of the induction motor 100 can rotate by the electromagnetic force caused by the induced current in the rotating magnetic field, thereby generating torque (T). e ).

[0062] Furthermore, the controller 200 according to an exemplary embodiment of this disclosure may include a torque error controller 205 for performing torque error control, and the torque error controller 205 may be based on the commanded torque (T) of the induction motor 100. e * ) and output torque (T) e The rotor resistance (R) of the induction motor 100 is determined by the error between the two values ​​and the temperature (x) of the induction motor 100. r ).

[0063] More specifically, the torque error controller 205 can perform torque error control, so that the output torque (T) of the induction motor 100 is controlled. e The command torque (T) can be tracked based on the temperature (x) of the induction motor 100. e * ), and the rotor resistance (R) can be determined based on the results of torque error control. r ).

[0064] Therefore, the torque error controller 205 can adjust the commanded torque (T) e * ), output torque (T) e The temperature (x) of the induction motor 100 and the rotor resistance (R) can be used as input values. r ) as the output value.

[0065] Here, the command torque (T) e * The torque can be directly input to the torque error controller 205, or it can be sent from the upstream controller; the output torque (T) e The torque can be the measured torque output by the induction motor 100, and can be measured by a sensor inside or outside the induction motor 100, and input to the torque error controller 205.

[0066] Furthermore, the temperature (x) of the induction motor 100 can refer to, for example, the temperature of the stator coil of the induction motor 100, and can be measured by a temperature sensor connected to the stator coil to be sent to the torque error controller 205. However, the temperature (x) of the induction motor 100 is not necessarily limited to the temperature of the stator coil, and can also include the temperature at any location inside or outside the induction motor 100, the rotor temperature, etc., and can be obtained not only by measuring and obtaining through a temperature sensor, but also through various temperature determination / estimation methods.

[0067] The torque error controller 205 can perform torque error control through feedback control to ensure that the output torque (T) is controlled correctly. e Based on input value, track command torque (T) e * And torque error control can be repeatedly performed until the commanded torque (T) is reached. e * ) and output torque (T) e The error between the rotor and the reference error becomes less than or equal to the predetermined reference error (e.g., "0"). The rotor resistance (R) r The torque error can be determined in real time based on the results of each torque error control, and can be re-determined and updated in real time during repeated torque error control.

[0068] Furthermore, torque error control can be performed, for example, by proportional-integral (PI) control, in which the control gain can be determined using the temperature (x) of the induction motor 100.

[0069] More specifically, the control gain for torque error control can be predetermined based on the temperature (x) and commanded torque (T) of the induction motor. e * The corresponding values ​​can be obtained, for example, from Tables 206 and 207, which store the temperature (x) and command torque (T) of the induction motor. e * Each of the corresponding control gains in )

[0070] In addition, such control gains may include commanded torque (T) e * ) and output torque (T) e ) proportional gain (K P ) and integral gain (K i ), and proportional gain (K P ) and integral gain (K i (This can be obtained through the corresponding gain tables 206 and 207.)

[0071] Furthermore, the rotor resistance (R) can be determined based on the results of torque error control. rFor this purpose, the torque of the induction motor 100 and the rotor resistance (R) can be utilized. r The relationship between (e.g., voltage-torque characteristic curve).

[0072] The following will refer to Figure 3 The operation performed by the torque error controller 205 is described in more detail.

[0073] Reference Figure 3 The diagram shows a control block diagram of the torque error controller 205 and illustrates the torque error control process performed by the torque error controller 205.

[0074] First, the torque error controller 205 can obtain the commanded torque (T) e * Subtract the output torque (T) from the total output torque. e (S310), and the commanded torque (T) can be determined. e * ) and output torque (T) e The error between ).

[0075] Subsequently, the torque error controller 205 can adjust the proportional gain (K) p ) is applied to the determined command torque (T) e * ) and output torque (T) e The value obtained by the error between (K) and the integral gain (K) i ) Applied to command torque (T) e * ) and output torque (T) e The error between the two values ​​is summed by integrating the values ​​obtained to perform proportional-integral control (S320).

[0076] For example, the output value as a result of proportional-integral control can be limited by a limit value used to prevent the accumulation of error integral values ​​(S330). For example, the torque error controller 205 can limit the anti-saturation gain (K) by... a The value obtained by subtracting the limit value from the output value, which is the result of proportional-integral control (S340), is then obtained by subtracting the limit value from the command torque (T). e * ) and output torque (T) e The error between the two values ​​is subtracted to perform integral control (S350), thereby preventing error divergence during integration.

[0077] In this way, the rotor resistance (Rr) determined based on the temperature of the induction motor 100 can be used to perform indirect vector control by reflecting the change of rotor resistance (Rr) with temperature.

[0078] On the other hand, return to reference Figure 2 When the rotor resistance (R) is determined in the torque error controller 205 r When the slip angular velocity determination unit 208 is in use, it can be based on the rotor resistance (R) determined in the torque error controller 205. r ), the d-axis current command (i) of the synchronous coordinate system generated in current command diagram 202 ds * ), q-axis current command (i qs * ), and rotor inductance (L r To determine the sliding angular velocity (ω) sl For example, for rotor inductance (L) r ), can be determined in advance through methods such as vehicle testing.

[0079] More specifically, the sliding angular velocity determining unit 208 can determine the sliding angular velocity using the following formula.

[0080]

[0081] Here, the sliding angular velocity (ω) sl The rotor resistance (R) can be determined based on the temperature of the induction motor 100 reflected in the torque error controller 205. r Therefore, the sliding angular velocity can be determined relatively accurately by reflecting the current rotor resistance (Rr).

[0082] Furthermore, the rotational angular velocity determination unit 209 can determine the rotational angular velocity (ω) of the rotor of the induction motor 100 based on the sensed value. r For example, the rotational angular velocity (ω) of the rotor can be determined by the rotor's position obtained via a position sensor (e.g., a resolver). r ).

[0083] The sliding angular velocity (ω) determined in the sliding angular velocity determination unit 208 can be used to determine the sliding angular velocity. sl ) and the rotational angular velocity (ω) determined in the rotational angular velocity determination unit 209 r The ω values ​​are added together to obtain the synchronous angular velocity of the rotating magnetic field. e Furthermore, the flux angle determination unit 210 can determine the synchronous angular velocity (ω) by... e Integrating the magnetic flux angle (θ) determines the magnetic flux angle. e ).

[0084] The magnetic flux angle (θ) determined in this way e ) can be used in the second converter 211 to convert the three-phase stator current (i) of the induction motor 100 as i bs ics ) converted to the d-axis current (i) in the synchronous coordinate system ds ) and q-axis current (i qs For example, the second converter 211 can receive the three-phase stator current (i) via a current sensor connected to the stator. as i bs i cs () as input.

[0085] Then, the current controller 203 can receive the converted d-axis current (i ds ) and q-axis current (i qs Feedback of ) and can perform current control, so that the d-axis current (i ds ) and q-axis current (i qs It can track d-axis current commands (i ds * ) and q-axis current command (i qs * ).

[0086] More specifically, the current controller 203 can control the converted d-axis current (i ds ) and q-axis current (i qs Feedback from ) to generate d-axis voltage commands (V) ds * ) and q-axis voltage command (V qs * ), so that the d-axis current (i ds ) and q-axis current (i qs Tracking d-axis current command (i ds * ) and q-axis current command (i qs * The generated d-axis voltage command (V) ds * ) and q-axis voltage command (V qs * It can be converted into a three-phase voltage command (V) by the first converter 204. an * V bn * V cn * Furthermore, the inverter 300 can be based on three-phase voltage commands (V... an * V bn * V cn * The AC voltage is output to the stator of the induction motor 100 through pulse width modulation control to drive the induction motor 100.

[0087] In an exemplary embodiment of this disclosure, the rotor resistance (R) can be reflected. r The change in sliding angular velocity (ω) with temperature variation is used to determine the sliding angular velocity. sl Accordingly, the magnetic flux angle (θ) can be obtained. e This controls the output of the induction motor 100, eliminating the need for a separate device to obtain the flux angle (θ). e A relatively accurate magnetic flux angle (θ) can be obtained using magnetic sensors, etc. e Specifically, compared to using a fixed value as the rotor resistance (R) r Compared to the case where the value of ) is reflected by the rotor resistance (R) r As the temperature of the induction motor 100 changes, a more accurate flux angle (θ) can be obtained. e And based on this, the output of the induction motor 100 can be controlled, thereby improving the accuracy of torque control.

[0088] The following will refer to Figure 4 A method for controlling a motor drive device according to an exemplary embodiment of the present disclosure is described.

[0089] Figure 4 This is a flowchart illustrating a method for controlling a motor drive device according to an exemplary embodiment of the present disclosure.

[0090] Reference Figure 4 First, a torque reference (S410) can be applied to cause the induction motor 100 to output a command torque. This torque reference can be determined by the required torque and can be applied directly to the controller 200 or sent from a higher-level controller connected to the controller 200.

[0091] After applying the torque command, the controller 200 can determine whether the induction motor 100 is being driven in an indirect vector control mode, that is, whether the flux angle is being indirectly determined by the sliding angular velocity, thereby controlling the output of the induction motor 100, instead of directly detecting the flux angle of the rotating magnetic field through a magnetic sensor or the like (S420). When the induction motor 100 is not being driven in an indirect vector control mode ("No" in S420), since there is no need to determine the sliding angular velocity, subsequent control can be omitted.

[0092] On the other hand, when the induction motor 100 is driven in an indirect vector control mode ("Yes" in S420), the controller 200 can obtain the temperature of the induction motor 100 required to determine the sliding angular velocity (S430). In this case, the temperature of the induction motor 100 is the temperature of the stator coil and is obtained by a temperature sensor connected to the stator coil.

[0093] Then, the controller 200 can determine the control gain for torque error control based on the obtained temperature and commanded torque of the induction motor 100 (S440). For example, the controller 200 can determine the control gain corresponding to the current commanded torque and temperature of the induction motor 100 by referring to a table storing control gains corresponding to the commanded torque and the temperature of the induction motor 100, respectively, wherein the control gain includes proportional gain and integral gain.

[0094] Once the control gain is determined, the controller 200 can perform torque error control based on the commanded torque, output torque, and control gain of the induction motor 100 to make the output torque track the commanded torque (S450), and can determine the value of the rotor resistance based on the result of the torque error control (S460).

[0095] Once the rotor resistance is determined, the controller 200 can determine the slip angular velocity based on the rotor resistance (S470), and when the error between the commanded torque and the output torque exceeds a predetermined reference error (e.g., "0") ("No" in S480), torque error control can be repeated to redetermine the value of the rotor resistance. Subsequently, when the error between the commanded torque and the output torque becomes less than or equal to the predetermined reference error (e.g., "0") according to torque error control ("Yes" in S480), torque error control can be terminated, and the value of the rotor resistance based on the current torque error control result can be maintained.

[0096] According to various exemplary embodiments of the present disclosure described above, by determining the sliding angular velocity by the value of the rotor resistance changing in real time, the estimation accuracy of the flux angle can be improved during indirect vector control, and correspondingly, the accuracy of torque control can be improved.

[0097] Furthermore, with the improvement of torque control accuracy, the command torque tracking performance can be improved without the need for a separate torque correction process.

[0098] Furthermore, various exemplary embodiments of this disclosure can be implemented by adding logic to an existing controller, thus achieving the above effects without increasing the size and cost of a separate hardware configuration.

[0099] Although specific exemplary embodiments of this disclosure have been shown and described above, it will be apparent to those skilled in the art that various improvements and modifications can be made to this disclosure without departing from the technical spirit of this disclosure (as described in the following claims).

Claims

1. A motor drive device, the device comprising: An induction motor includes a stator and a rotor, the rotor rotating by a rotating magnetic field generated in the stator; and The controller is configured as follows: The resistance of the rotor is determined based on the error between the command torque and the output torque of the induction motor and the temperature of the induction motor. as well as The output of the induction motor is controlled based on the determined resistance of the rotor.

2. The apparatus according to claim 1, wherein, The controller is configured to: Torque error control is performed based on the temperature of the induction motor to ensure that the output torque tracks the commanded torque; and The resistance of the rotor is determined based on the results of torque error control.

3. The apparatus according to claim 2, wherein, The controller is configured to: The torque error control is repeatedly performed, and the resistance of the rotor is determined, until the error between the commanded torque and the output torque becomes less than or equal to a predetermined reference error.

4. The apparatus according to claim 2, wherein, The controller is configured to: Torque error control is performed based on a pre-determined control gain corresponding to the temperature of the induction motor and the commanded torque.

5. The apparatus according to claim 4, wherein, The control gain includes a proportional gain and an integral gain for the error between the commanded torque and the output torque.

6. The apparatus according to claim 4, wherein, The controller is configured to: Torque error control is performed by applying a control gain that stores control gain values ​​corresponding to the temperature of the induction motor and the commanded torque.

7. The apparatus according to claim 2, wherein, The controller is configured to: The torque error control is corrected by anti-saturation measures against the error between the commanded torque and the output torque; and The resistance of the rotor is determined based on the results of the corrected torque error control.

8. The apparatus according to claim 1, wherein, The temperature of the induction motor is the temperature of the stator coil.

9. The apparatus according to claim 1, wherein, The controller is configured to: Based on the resistance of the rotor, the sliding angular velocity of the induction motor is determined; and The output of the induction motor is controlled based on the determined sliding angular velocity.

10. The apparatus according to claim 9, further comprising: An inverter is configured to drive the induction motor. The controller is configured as follows: Based on the sliding angular velocity, the stator current is converted to the synchronous coordinate system; and The inverter is controlled by pulse width modulation (PWM) control based on the converted current, thereby controlling the output of the induction motor.

11. A method for controlling a motor drive device, the method comprising the following steps: The resistance of the rotor is determined based on the error between the command torque and the output torque of the induction motor and the temperature of the induction motor. The induction motor includes a stator and the rotor, and the rotor rotates by a rotating magnetic field generated in the stator. as well as The output of the induction motor is controlled based on the determined resistance of the rotor.

12. The method according to claim 11, wherein, The steps for determining the resistance of the rotor include: Torque error control is performed based on the temperature of the induction motor to ensure that the output torque tracks the commanded torque; and The resistance of the rotor is determined based on the results of torque error control.

13. The method according to claim 12, wherein, The steps for determining the resistance of the rotor include: The torque error control is repeatedly performed, and the resistance of the rotor is determined, until the error between the commanded torque and the output torque becomes less than or equal to a predetermined reference error.

14. The method according to claim 12, wherein, The steps for determining the rotor resistance include: Torque error control is performed based on a pre-determined control gain corresponding to the temperature of the induction motor and the commanded torque.

15. The method according to claim 14, wherein, The control gain includes a proportional gain and an integral gain for the error between the commanded torque and the output torque.

16. The method of claim 14, wherein, The steps for determining the resistance of the rotor include: Torque error control is performed by applying control gains stored in a table that corresponds to the control gains of the induction motor and the commanded torque, respectively.

17. The method according to claim 12, wherein, The steps for determining the resistance of the rotor include: The torque error control is corrected by anti-saturation measures targeting the error between the commanded torque and the output torque; and The resistance of the rotor is determined based on the results of the corrected torque error control.

18. The method according to claim 11, wherein, The temperature of the induction motor is the temperature of the stator coil.

19. The method according to claim 11, wherein, The steps for controlling the output of the induction motor include: Based on the resistance of the rotor, the sliding angular velocity of the induction motor is determined; and The output of the induction motor is controlled based on the determined sliding angular velocity.

20. The method according to claim 19, wherein, The steps for controlling the output of the induction motor include: Based on the sliding angular velocity, the stator current is converted to the synchronous coordinate system; and The output of the induction motor is controlled by controlling the inverter used to drive the induction motor through pulse width modulation control based on the converted current.

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