Motor drive device and method for determining the temperature of a power module

Abstract

A motor drive device comprises: a drive unit implemented as at least one power module and including an upper switch, a lower switch, and a changeover switch configured to switch a motor drive mode; and a controller configured to determine a power loss of each of the upper switch, the lower switch, and the changeover switch to obtain a total power loss of the at least one power module, and to determine a temperature of the at least one power module based on the total power loss.

Description

BACKGROUND OF THE PRESENT DISCLOSURE Field of the present disclosure

[0001] The present disclosure relates to a method for determining the temperature of a power module in a motor drive device. Description of the state of the art

[0002] Generally, the one-sided ends of the windings with the respective phases contained in an electric vehicle motor are connected to an inverter and the other ends are connected together, forming a Y connection.

[0003] When the motor is driven, a switching element in the inverter is switched on or off by pulse width modulation to apply a mains voltage to the Y-connected windings of the motor, thus generating alternating current that creates torque.

[0004] Since the fuel efficiency (or electricity cost) of environmentally friendly vehicles, such as electric vehicles that use the torque generated by the motor as power, depends on the efficiency of power conversion between the inverter and the motor, it is important to maximize the power conversion efficiency of the inverter and the efficiency of the motor to improve fuel efficiency.

[0005] The efficiency of an inverter-motor system is mainly determined by the voltage utilization rate of the inverter, and the fuel efficiency of the vehicle can be improved if the vehicle's operating point, which is determined by the relationship between the speed and torque of the motor, is formed in a section with a high voltage utilization rate.

[0006] However, as the number of windings of the motor is increased to increase the motor's maximum torque, a high-voltage utilization section may be farther away from a low-torque region, which is the vehicle's main operating point, resulting in poor fuel efficiency. Furthermore, the main operating point may be designed to be in the high-voltage utilization section from a fuel efficiency perspective, limiting the motor's maximum torque and reducing the vehicle's acceleration performance.

[0007] In the field of the present disclosure, there is a need for a motor drive technology that can cover both low and high power intervals with a single motor while simultaneously improving system efficiency. Therefore, a technology has recently been introduced that uses two inverters and switches to drive a single motor in two different modes.

[0008] The information contained in this background of the present disclosure is provided merely to facilitate understanding of the general background of the present disclosure and should not be construed as an acknowledgment or any form of indication that this information constitutes prior art already known to a person skilled in the art. BRIEF OVERVIEW

[0009] Various aspects of the present disclosure relate to determining the temperature of a power module considering an engine operating mode and the operating state of an engine.

[0010] The technical topics pursued in an exemplary embodiment of the present disclosure are not limited to the above-mentioned technical topics, and other technical topics not mentioned can be clearly understood by those skilled in the art to which the present disclosure relates through the following descriptions.

[0011] To address the above technical aspect, a motor drive device according to an exemplary embodiment of the present disclosure may include: a drive unit implemented as at least one power module having at least one switch, and including an upper switch and a lower switch configured to drive a motor based on a motor drive mode, and a changeover switch configured to switch the motor drive mode; and a controller configured to determine a power loss of each of the upper switch, the lower switch, and the changeover switch based on the motor drive mode and an operating state of the motor to obtain a total power loss of the at least one power module, and to determine a temperature of the at least one power module based on the total power loss.

[0012] Furthermore, as a means for addressing the above technical aspect, a method for determining a temperature of at least one power module including at least one switch in a drive unit implemented as the at least one power module and including an upper switch and a lower switch configured to drive a motor based on a motor drive mode, and a changeover switch configured to switch the motor drive mode, may comprise: determining a power loss of each of the upper switch, the lower switch, and the changeover switch based on the motor drive mode and an operating state of the motor to obtain a total power loss of the at least one power module; and determining a temperature of the at least one power module based on the total power loss.

[0013] According to an exemplary embodiment of the present disclosure, the accuracy of estimating the temperature of the at least one power module can be improved by determining the temperature of the at least one power module taking into account the motor drive mode and the operating state of the motor without a separate temperature sensor, and switching elements in the at least one power module can be protected by controlling a current in the at least one power module based on the determined temperature.

[0014] The advantageous effects that can be achieved by the present disclosure are not limited to the above-mentioned effects, and other effects not mentioned can be clearly understood by those skilled in the art to which the present disclosure relates from the following descriptions.

[0015] The methods and apparatus of the present disclosure have additional features and advantages that will be apparent from, or more particularly set forth in, the accompanying drawing figures included herein and the following detailed description, which together serve to explain certain principles of the present disclosure. BRIEF DESCRIPTION OF THE DRAWING FIGURES Fig. 1 is a circuit diagram according to an example of a motor drive device according to an exemplary embodiment of the present disclosure. Fig. 2 illustrates switching of a motor drive mode according to an exemplary embodiment of the present disclosure. Fig. 3 shows the configuration of a power module according to an exemplary embodiment of the present disclosure. Fig. 4 is a flowchart illustrating a method for determining the temperature of a power module by a controller according to an exemplary embodiment of the present disclosure. Fig. 5 illustrates a process in which a controller is configured to determine the power losses of an upper switch and a lower switch of a power module in a CEW mode, according to an exemplary embodiment of the present disclosure. Fig. 6 is a diagram corresponding to an IV curve of a switching element in a power module according to an exemplary embodiment of the present disclosure. Fig. 7 illustrates a process in which a controller is configured to determine the power losses of an upper switch and a lower switch of a power module in an OEW mode, in accordance with an exemplary embodiment of the present disclosure. Fig. 8 illustrates a method in which a controller measures the thermal resistance of a power module according to an exemplary embodiment of the present disclosure. Fig. 9 illustrates a process in which a controller corrects a thermal resistance measurement of a power module based on a coolant flow rate of the power module, according to an exemplary embodiment of the present disclosure. Fig. 10 shows a method in which a controller corrects temperature variations of a power module according to an exemplary embodiment of the present disclosure.

[0016] The accompanying drawing figures are not necessarily to scale and represent a somewhat simplified representation of various features illustrating the basic principles of the present disclosure. The specific design features of the present disclosure as contained herein, including, for example, specific dimensions, orientations, positions, and shapes, will be determined in part by the particular intended application and environment of use.

[0017] In the drawing figures, reference numerals refer to the same or equivalent parts of the present disclosure in the different figures of the drawing. DETAILED DESCRIPTION

[0018] Reference will now be made in detail to various embodiments of the present disclosure(s), examples of which are illustrated in the accompanying drawing figures and described below. Although the present disclosure(s) are described in connection with exemplary embodiments of the present disclosure, this description is not intended to limit the present disclosure(s) to these exemplary embodiments of the present disclosure. On the contrary, the present disclosure(s) are intended to cover not only the exemplary embodiments of the present disclosure, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the present disclosure as defined by the appended claims.

[0019] Various exemplary embodiments will be described in detail below with reference to the accompanying drawing figures. The same or similar elements are designated by the same and similar reference numerals regardless of the figure numbers, so that duplicate descriptions can be omitted. The terms "module" and "unit" used for the elements in the following description are used only to simplify the description and do not have different meanings or roles in themselves. Furthermore, in describing the exemplary embodiments presented herein, a detailed description of known relevant technologies is omitted if it is determined that the description might obscure the subject matter of the present disclosure.Furthermore, it should be noted that the attached drawing figures are only for facilitating the understanding of the exemplary embodiments shown herein, and that the technical idea of ​​the present disclosure is not limited to the attached drawing figures and includes all modifications, equivalents, or alternatives that fall within the spirit and scope of the present disclosure.

[0020] Terms that include an atomic number, such as "a first" and "a second," can be used to describe different elements, but the elements are not limited to these terms. The above terms are used simply to distinguish one element from others.

[0021] When an element is described as "connected" or "coupled" to other elements, not only can the element be directly connected or coupled to the other elements, but another element can also be interposed. On the other hand, when an element is described as "directly connected" or "directly coupled" to another element, it is assumed that no other element is interposed.

[0022] A singular expression may include a plural expression unless the two expressions are clearly distinct in a particular context.

[0023] As used herein, the terms "comprise," "include," or "have" are intended to indicate the presence of the recited features, numbers, steps, operations, elements, components, or combinations thereof and are to be construed not to preclude the possible presence or addition of one or more other features, numbers, steps, operations, elements, components, or combinations thereof.

[0024] A unit or control unit included in terms such as engine control unit (MCU) is merely a widely used term for a controller (control unit) configured to control a specific function of a vehicle, but does not imply a general functional unit. For example, to control a function for which a control unit is responsible, each control unit may include a communication device configured to communicate with a sensor or other control unit, a memory configured to store an operating system, a logical command, or input / output information, and at least one processor configured to perform determinations, calculations, decisions, or the like necessary to control the responsible function.

[0025] Fig. 1 is a circuit diagram according to an example of a motor drive device according to an exemplary embodiment of the present disclosure.

[0026] Referring to Fig. 1, a motor drive device according to various exemplary embodiments of the present disclosure may include a first inverter 10, a second inverter 20, a motor 30 having a plurality of windings C1, C2, and C3 corresponding to multiple phases, a mode switching unit 40, a battery 50, a DC capacitor (or a DC link capacitor) 60, and a controller 70.

[0027] The first inverter 10 may include a plurality of first switching elements S11, S12, S13, S14, S15, and S16 connected to the one-side ends of the plurality of windings C1, C2, and C3, and the second inverter 20 may include a plurality of second switching elements S21, S22, S23, S24, S25, and S26 connected to the other-side ends of the plurality of windings C1, C2, and C3. The mode switching unit 40 may include a plurality of changeover switches S31, S32, and S33 connected between the other ends of the plurality of windings C1, C2, and C3 and a neutral end for the plurality of windings C1, C2, and C3. The control unit 70 may be configured to control the ON / OFF state of the first switching elements S11, S12, S13, S14, S15, and S16, the second switching elements S21, S22, S23, S24, S25, and S26, and the changeover switches S31, S32, and S33 based on a motor request output (i.e., a torque command to the motor), the intermediate circuit voltages of the inverters 10 and 20 (i.e.,i.e. a battery voltage), a motor phase current and a motor angle.

[0028] The first inverter 10 may include a plurality of branches 11, 12, 13 to which a DC voltage is applied, which is generated in a DC capacitor 60 connected between both ends of the battery 50. The branches 11, 12, and 13 may each be electrically connected to a plurality of phases of the motor 30. The first branch 11 may include two switching elements S11 and S12 connected in series between both ends of the DC capacitor 60, and a connection node of the two switching elements S11 and S12 may be connected to one end of the winding C1 of a phase in the motor 30, so that AC power is input and output according to one of the plurality of phases.Similarly, the second branch 12 may include two switching elements S13 and S14 connected in series between both ends of the DC capacitor 60, and a connection node for the two switching elements S13 and S14 may be connected to one end of the winding C2 of one phase in the motor 30, so that AC power corresponding to one of the multiple phases is input and output. Furthermore, the third branch 13 may include two switching elements S15 and S16 connected in series between both ends of the DC capacitor 60, and a connection node for the two switching elements S15 and S16 may be connected to one end of the windings C3 of one phase in the motor 30, so that AC power corresponding to one of the multiple phases is input and output.

[0029] The second inverter 20 may include a plurality of branches 21, 22, and 23 to which a DC voltage generated in the DC capacitor 60 connected between both ends of the battery 50 is applied. The branches 21, 22, and 23 may each be electrically connected to a plurality of phases of the motor 30. The first branch 21 may include two switching elements S21 and S22 connected in series between the two ends of the DC capacitor 60, and a connection node for the two switching elements S21 and S22 may be connected to the other end of the winding C1 of one phase of the motor 30 so that the AC power corresponding to one of the plurality of phases is input and output.Similarly, the second branch 22 may include two switching elements S23 and S24 connected in series between the two ends of the DC capacitor 60, and a connection node for the two switching elements S23 and S24 may be connected to the other end of the winding C2 of one phase in the motor 30 such that AC power corresponding to one of the multiple phases is input and output. Furthermore, the third branch 23 may include two switching elements S25 and S26 connected in series between the two ends of the DC capacitor 60, and a connection node for the two switching elements S25 and S26 may be connected to the other end of the winding C3 of one phase in the motor 30 such that AC power corresponding to one of the multiple phases is input and output.

[0030] The one-sided ends of the plurality of switches S31, S32, and S33 can be connected to the other ends of the plurality of windings C1, C2, and C3 in the motor 30, while the other ends of the plurality of switches S31, S32, and S33 can be connected to the neutral end of the motor 30. Various switching means known in the art, such as MOSFETs, IGBTs, thyristors, relays, and the like, can be used for the plurality of switches S31, S32, and S33.

[0031] Although in Fig. 1, the motor drive device may further include a so-called Y-capacitor (Y-cap) that connects two series-connected capacitors between a positive (+) DC link and a negative (-) DC link and grounds a connection node between the capacitors.

[0032] The controller 70 may be configured to control the drive of the motor 30 by switching the switching elements S11, S12, S13, S14, S15 and S16 and S21, S22, S23, S24, S25 and S26 included in the first inverter 10 and the second inverter 20 by pulse width modulation based on the output power required by the motor 30.

[0033] Furthermore, the controller 70 can control the ON / OFF state of the third switching elements S31, S32, and S33 included in the mode switching unit 40 based on the motor drive modes. The motor drive modes can include a first drive mode and a second drive mode. The first drive mode can be referred to as a "closed-end winding (CEW) mode," and the second drive mode can be referred to as an "open-end winding (OEW) mode."

[0034] The controller 70 may be configured to control the changeover switches S31, S32, and S33 to be in an ON state when the CEW mode is executed, and may be configured to control the drive of the motor 30 by the first inverter 10 of the two inverters 10 and 20. The changeover switches S31, S32, and S33 in the ON state may electrically connect the other ends of the plurality of windings C1, C2, and C3 to the neutral end for the plurality of windings C1, C2, and C3, respectively.

[0035] In contrast, the control unit 70 may be configured to control the changeover switches S31, S32, and S33 to be in an OFF state when the OEW mode is executed, and may be configured to control the drive of the motor 30 by the two inverters 10 and 20. The changeover switches S31, S32, and S33 may, in the OFF state, electrically disconnect the other ends of the plurality of windings C1, C2, and C3 from the neutral end of the plurality of windings C1, C2, and C3.

[0036] Fig. 2 illustrates switching of a motor drive mode according to an exemplary embodiment of the present disclosure.

[0037] Fig. 2 shows an engine operating point map illustrating a power limit curve L1 in a CEW mode, a power limit curve L2 in an OEW mode, and a mode switching reference line L3 using an efficiency map.

[0038] Output limit curves L1 and L2 may represent limits for the motor's output torque at each motor speed (e.g., RPM) in the respective motor drive modes. Power limit curve L2 may include a power limit that is greater than or equal to power limit curve L1 in at least some speed ranges. Power limit curves L1 and L2 may be configured to consider the service life, heat generation capability, and current controllability of the motor and inverter.

[0039] The reference line L3 for mode switching, based on the efficiency map, can correspond to the boundary between a high-efficiency region in CEW mode and a high-efficiency region in OEW mode. The efficiency map can include information on which of the two modes, CEW and OEW, is more efficient for each combination of motor torque and inverse magnetic flux, and can be in the form of a table, depending on the implementation. The efficiency map can, for example, be derived from the result of measuring motor loss through tests as a function of motor speed and torque in each motor drive mode for each inverter DC link voltage. In the present case, the motor inverse magnetic flux can be inversely proportional to the inverter DC link voltage (i.e., the battery voltage) and proportional to the motor speed.

[0040] According to an exemplary embodiment of the present disclosure, the mode change reference line L3 may have the same shape as L3' depending on the specification of the motor drive device. Fig. However, the mode switching reference lines L3 and L3' shown in Figure 2 are exemplary, and the present disclosure is not necessarily limited thereto.

[0041] To switch the motor drive mode according to the mode switching reference line L3, the controller 70 may switch the CEW mode and the OEW mode in both directions according to the value of a torque command to the motor and the value of the inverse magnetic flux with reference to the efficiency map. In this case, the value of the inverse magnetic flux may be determined based on the torque command to the motor, the DC link voltage of the inverter, and the required speed of the motor. According to an exemplary embodiment of the present disclosure, the controller 70 may correct the mode switching reference line by taking into account an output limit or hysteresis in the motor drive mode, in which case the motor drive mode may be switched according to the value of the torque command to the motor and the value of the inverse magnetic flux based on the calibrated mode switching threshold.

[0042] On the other hand, each switching element in the inverter can heat up to such a high temperature due to conduction and switching losses that occur during switching that it can be modularized into a power module with a separate cooling structure. If the power module has a temperature higher than a specified temperature, the internal switching elements of the power module may burn out, so it is necessary to estimate the temperature of the power module and control the power module's current based on the estimated temperature.

[0043] On the other hand, a drive unit according to an exemplary embodiment of the present disclosure may be implemented as at least one power module with at least one switch, and may include an upper switch and a lower switch configured to drive the motor based on the motor drive mode, as well as a changeover switch configured to change the motor drive mode. For example, the drive unit may be implemented as a single power module with the upper switch, the lower switch, and the changeover switch. Alternatively, the drive unit may be implemented in a manner in which the upper switch, the lower switch, and the changeover switch are distributed across a plurality of different power modules. The configuration of the power module for implementing the drive unit is described with reference to Fig. 3 described.

[0044] Fig. 3 shows the configuration of a power module according to an exemplary embodiment of the present disclosure.

[0045] As in Fig. 3, the power module according to an exemplary embodiment of the present disclosure may include an upper switch S21 and a lower switch S22 included in the second inverter 20, and a changeover switch S31 included in the mode switching unit 40. The power module in the Fig. The form shown in Figure 3 has three switching elements and can therefore be referred to as a 3-in-1 power module. In this case, an upper switch S23, a lower switch S24, and a changeover switch S32 can form another 3-in-1 power module, and an upper switch S25, a lower switch S26, and a changeover switch S33 can form another 3-in-1 power module. Furthermore, an upper switch and a lower switch included in the first inverter 10 can also form a separate power module.

[0046] An output terminal O, a switching terminal C, a negative terminal N, and a positive terminal P may be arranged on one side of the power module, and the control pins PIN_B, PIN_C, and PIN_T may be arranged on the other side opposite one side of the power module. The power module can receive signals for controlling the on-state of the upper switch S21, the changeover switch S31, and the lower switch S22 via the control pin PIN_B, the control pin PIN_C, and the control pin PIN_T, respectively. In this case, the upper switch S21 may be arranged between the positive terminal P, which is connected to a positive electrode of the battery, and the output terminal O, which is connected to one end of a winding included in the motor.The lower switch S22 can be arranged between the negative terminal N, which is connected to the negative electrode of the battery, and the output terminal O, which is connected to one end of the winding contained in the motor. The changeover switch S31 can be arranged between the output terminal O, which is connected to one end of the winding contained in the motor, and the switching terminal C, which is connected to the neutral end of the motor.

[0047] In contrast to the representation in Fig. 3, the power module can also be designed as a 5-in-1 power module with an upper switch S11 and a lower switch S12 in the first inverter 10, the upper switch S21 and the lower switch S22 in the second inverter 20 and the changeover switch S31 in the mode switching unit 40.

[0048] For the upper switch S21 and the lower switch S22 of the second inverter 20, which control the motor based on the motor drive mode, and the changeover switch S31, which switches the motor drive mode, the power loss must be determined differently depending on the motor drive mode and the operating state of the motor.

[0049] The present disclosure proposes a method for determining the temperature of a power module including a switching element of a second inverter and a transfer switch based on a motor operating mode and an operating state of a motor. For simplicity, the present disclosure will be described below assuming that the power module is a 3-in-1 power module. However, the present disclosure can be applied to various types of power modules, such as 5-in-1 power modules.

[0050] Fig. 4 is a flowchart illustrating a method for determining the temperature of a power module by a controller according to an exemplary embodiment of the present disclosure.

[0051] Referring to Fig. 4, the controller 70 may obtain a total power dissipation of the power module based on the motor drive mode and the operating state of the motor, and determine a temperature of the power module based on the total power dissipation of the power module, the thermal resistance measurement, and the coolant temperature of the power module.

[0052] The temperature of the power module can be determined as shown in Equation 1 below. Power module temperature = power module temperature change × RC filter value + power module coolant temperature.

[0053] The RC filter value can be determined from experimental data obtained by applying a specific root-mean-square current to the drive unit and measuring the resulting temperature. The temperature variation of the power module can be equal to the product of the total power dissipation of the power module, the measured thermal resistance of the power module, and the correction constant for the coolant flow rate (LPM), as shown in Equation 2 below. Power module temperature fluctuation = total power loss of the power module × thermal resistance measurement of the power module × correction constant of the coolant flow rate (LPM)

[0054] First, the controller 70 may be configured to determine a motor drive mode and an operating state of the motor (S101).

[0055] The controller 70 can be configured to determine whether the motor drive mode is a CEW mode or an OEW mode. The CEW mode may correspond to a mode in which the upper switch and the lower switch included in the second inverter are turned off, and the changeover switch included in the mode switching unit is turned on to form a neutral point of the motor. In contrast, the OEW mode may correspond to a mode in which the upper switch and the lower switch in the second inverter are switched complementarily to drive the motor, and the changeover switch in the mode switching unit is turned off.

[0056] Furthermore, the controller 70 may be configured to determine whether the operating state of the motor is a starting state or a restricted state based on the rotational speed (e.g., RPM) of the motor 30. The controller may determine the rotational speed of the motor via a resolver or encoder, etc. The controller 70 may be configured to determine that the operating state of the motor is a restricted state when the rotational speed (RPM) is 0, and may be configured to determine that the operating state of the motor is a starting state when the rotational speed (RPM) is not 0. The starting state may be defined as a state in which the motor is rotating while the motor torque is being generated, and the restricted state may be defined as a state in which the motor is not rotating while the motor torque is being generated.The restricted state of the engine may, for example, correspond to the state in which the vehicle is stopped on an incline using the accelerator pedal without applying the brakes.

[0057] Thereafter, the controller 70 may be configured to determine the power loss of the upper switch, the lower switch, and the changeover switch included in the power module based on the motor drive mode and the operating state of the motor to obtain the total power loss of the power module (S102).

[0058] When CEW mode is executed, the upper and lower switches in the second inverter are turned off, but the transfer switch is turned on, resulting in line losses due to the motor's phase current. Accordingly, the controller 70 may be configured to determine a transfer switch power loss when CEW mode is executed, which is included in the total power loss of the power module. Fig. 5 shows a method in which the controller is configured to determine the power loss of the switch of the power module in CEW mode.

[0059] The left side of Fig. Figure 5 shows the motor current waveform when the motor's operating state in CEW mode is the start state. When the current is positive (+), a diode of the changeover switch may be conducting, and when the current is negative (-), a transistor of the changeover switch may be conducting. In this case, the current flowing in each phase of the three-phase motor may have a waveform imax*sin(wt) with a phase of 120 degrees.

[0060] Fig. Figure 6 shows a diagram corresponding to the IV curve of a switching element. In the IV curve, the relationship between voltage and current follows the equation "V = I*Rdson + Vceo" at a certain current level or higher. Vceo and Rdson can correspond to the characteristics of the IV curve. The power dissipation of a switching element can be expressed as the product of the voltage (V) and current (I) of the switching element.

[0061] When the operating state of the motor in CEW mode is the start state, the controller 70 may be configured to determine the transistor loss and the diode loss of the switch based on the maximum value (imax) of a sinusoidal current supplied to the switch.

[0062] When the operating state of the motor in CEW mode is the starting state, the transistor loss (Pigbt_split) of the switch can be determined as shown in Equation 3 below. Pigbt_split=Vceo*imaxπ+Rdson4∗imax2

[0063] When the operating state of the motor in CEW mode is the starting state, the diode loss (Pdiode_split) of the switch can be determined as shown in Equation 4 below. Where, Vo,diode and Rt,diode can correspond to the characteristics of the diodes corresponding to Vceo and Rdson, respectively. Pdiode_split=Vo,diode*imaxπRt,diode4*imax2

[0064] The right side of Fig. Figure 5 shows a motor current waveform when the motor's operating state is the restricted state in CEW mode. As shown in the upper right, the switch's diode can be conductive when the current is positive (+), and as shown in the lower right, the switch's transistor can be conductive when the current is negative (-).

[0065] In the restricted state, the motor speed is zero, so the current in the restricted state, unlike in the started state, does not have the form of a sine wave, but may take the form of a direct current. Since the formula for the starting state, which can be determined assuming a sine wave, cannot be used, and since the imax value can vary depending on the motor angle, the power loss can be determined using the phase current measurement ^i. Accordingly, the controller 70 can be configured to determine the transistor loss or the diode loss of the switch from the phase current measurement of the motor when the operating state of the motor in CEW mode is the restricted state.

[0066] When power dissipation is determined based on the phase current measurement ^i, the frequency of the phase current in the restricted state is low enough to avoid aliasing, and one current value in each phase can be used. Therefore, the accuracy of power dissipation determination can be improved, resulting in improved temperature estimation performance.

[0067] When the operating state of the motor in CEW mode is the restricted state, the diode loss (Pdiode) of the switch can be determined as shown in Equation 5 below. Digbt refers to the duty cycle. Pdiode=Digbt*i*(Vo,Diode+Rt,Diode*i)

[0068] When the operating state of the motor in CEW mode is the restricted state, the transistor loss (Pigbt) of the switch can be determined as shown in Equation 6 below. Pigbt=Digbt*i*(Vceo+Rdson*i)

[0069] When operating in OEW mode, the transfer switch is off, but the upper and lower switches in the second inverter are switched complementarily to drive the motor. Therefore, conduction losses and switching losses may occur due to the motor's phase current. Accordingly, when operating in OEW mode, the controller 70 can be configured to determine the power losses of the upper switch and the lower switch, which are included in the total power loss of the power module. Fig. 7 shows a method in which the controller 70 is configured to determine the power dissipation of the upper switch and the lower switch of the power module in OEW mode.

[0070] The left side of Fig. 7 shows a motor current waveform when the operating state of the motor in the OEW mode is a start state. The upper left side shows a current waveform when the motor is energized, where when the current is positive (+), the transistor of the lower switch may be conductive, and when the current is negative (-), the transistor of the upper switch may be conductive. Accordingly, the controller 70 may be configured to determine the transistor losses of the upper switch and the lower switch based on the maximum value of the sinusoidal current supplied to the upper switch and the lower switch when the operating state of the motor in the OEW mode is the start state and when the motor is energized.The lower left side shows a current waveform in a state where power is regenerated from the motor. When the current is positive (+), the diode of the lower switch may be conductive, and when the current is negative (-), the diode of the upper switch may be conductive. Accordingly, the controller 70 may be configured to determine the diode losses of the upper switch and the lower switch based on the maximum value of the sinusoidal current supplied to the upper switch and the lower switch when the operating state of the motor in the OEW mode is the started state and power is regenerated from the motor (i.e., the regenerative braking state).

[0071] The right side of Fig. Figure 7 shows the waveform of a motor current when the operating state of the motor in OEW mode is a restricted state. As shown in the upper right, the lower switch transistor may be conductive when the current is positive (+), and as shown in the lower right, the upper switch transistor may be conductive when the current is negative (-). Accordingly, when the operating state of the motor in OEW mode is the restricted state, the controller 70 may be configured to determine an upper switch transistor loss or a lower switch transistor loss based on a motor phase current measurement.

[0072] The controller 70 may then determine the thermal resistance of the power module (S103). The thermal resistance of the power module may be determined while a cooler is coupled to the power module and may be determined based on: a loss IV while a current flows to the corresponding element; and the temperature of the element when the current is conducted. The controller 70 may obtain the thermal resistance of the power module by obtaining an externally determined or measured resistance of the power module. Alternatively, the controller 70 may also directly determine the thermal resistance of the power module.

[0073] Fig. 8 illustrates a process in which the controller 70 measures the thermal resistance of the power module according to an exemplary embodiment of the present disclosure. "A" may correspond to a conduction direction of a current for measuring the thermal resistance to a transistor of the upper switch S21, and "B" may correspond to a conduction direction of a current for measuring the thermal resistance to a diode of the upper switch S21. Furthermore, "C" may correspond to a conduction direction of a current for measuring the thermal resistance at a transistor of the switch S31, and "D" may correspond to a conduction direction of a current for measuring the thermal resistance at a diode of the switch S31.Similarly, "E" may correspond to a conduction direction of a thermal resistance measuring current to a transistor of the lower switch S22, and "F" may correspond to a conduction direction of a thermal resistance measuring current to a diode of the lower switch S22.

[0074] When measuring the thermal resistance of the power module, the thermal resistance varies depending on the flow rate of a coolant flowing through the radiator of the power module, so the controller 70 can multiply a thermal resistance measurement value by a coolant flow rate correction constant to correct the thermal resistance measurement value of the power module and determine the temperature change of the power module (S104). The coolant flow rate (LPM)-dependent correction constant is Fig. 9. From Fig. 9, it can be seen that the value of the coolant flow correction constant (LPM) decreases as the coolant flow rate (LPM) increases. The controller can obtain the coolant flow correction constant (LPM) using a lookup table or formula that reflects the relationship between the flow rate (LPM) and the flow correction constant (LPM), as shown in Fig. 9 shown.

[0075] Since the temperature variation of the power module corresponds to the amount of change when the corresponding temperature is saturated, the controller 70 may multiply a temperature variation of the power module by an RC filter value based on the Foster thermal model to obtain the actual temperature variation of the power module modeled as the actual impedance (S105). Fig.10 illustrates a process in which the controller is configured to determine an actual temperature change of the power module from the temperature change of the power module.

[0076] Finally, the controller 70 may be configured to determine the internal temperature of the power module by adding a coolant temperature of the power module to the actual temperature change of the power module obtained in operation S105 (S106). Furthermore, the control unit 70 may control the operation of the drive unit, such as controlling the turning on and off of the upper switch, the lower switch, and the changeover switch, based on the internal temperature of the generated power module. Furthermore, the controller 70 may control the cooler, etc., based on the internal temperature of the generated power module.

[0077] Furthermore, the term "controller," "control apparatus," "control unit," "control device," "control module," "control circuit," or "server," etc., refers to a hardware device having a memory and a processor configured to execute one or more steps interpreted as an algorithm structure. The memory stores algorithm steps, and the processor executes the algorithm steps to perform one or more processes of a method in accordance with various exemplary embodiments of the present disclosure.The control device according to exemplary embodiments of the present disclosure may be implemented by a non-volatile memory configured to store algorithms for controlling the operation of various components of a vehicle or data via software instructions for executing the algorithms, and a processor configured to perform the above-described process using the data stored in the memory. The memory and the processor may be individual chips. Alternatively, the memory and the processor may be integrated into a single chip. The processor may be implemented as one or more processors. The processor may include various logic circuits and operating circuits, may be configured to process data according to a program provided by the memory, and may be configured to generate a control signal according to the processing result.

[0078] The control device may be at least one microprocessor controlled by a predetermined program that may include a series of instructions for performing the method included in the above-mentioned various exemplary embodiments of the present disclosure.

[0079] The aforementioned invention may also be embodied as computer-readable code on a computer-readable recording medium. The computer-readable recording medium is any data storage device capable of storing data that can subsequently be read by a computer system and of storing and executing program instructions that can subsequently be read by a computer system. Examples of computer-readable recording media include hard disk drives (HDDs), solid-state disks (SSDs), silicon disk drives (SDDs), read-only memories (ROMs), random access memories (RAMs), CD-ROMs, magnetic tapes, floppy disks, optical data storage devices, etc., and implementation as carrier waves (e.g., transmission over the Internet). Examples of program instructions include machine language codes generated by a compiler and high-level language codes that can be executed by a computer using an interpreter or the like.

[0080] In various exemplary embodiments of the present disclosure, each operation described above may be performed by one control device, and the control device may be implemented by a plurality of control devices or an integrated single control device.

[0081] In various exemplary embodiments of the present disclosure, the memory and the processor may be provided as one chip or as separate chips.

[0082] In various exemplary embodiments of the present disclosure, the scope of the present disclosure includes software or machine-executable instructions (e.g., an operating system, an application, firmware, a program, etc.) that enable operations according to the methods of various embodiments to be performed on a device or a computer, and a non-transitory computer-readable medium on which such software or instructions are stored and that can be executed on the device or the computer.

[0083] In various exemplary embodiments of the present disclosure, the controller may be implemented in hardware or software, or in a combination of hardware and software.

[0084] Software implementations may include software components (or elements), object-oriented software components, class components, task components, processes, functions, attributes, procedures, subroutines, program code segments, drivers, firmware, microcode, data, databases, data structures, tables, arrays, and variables. The software, data, and the like may be stored in memory and executed by a processor. The memory or processor may use a variety of means known to a person of ordinary skill in the art.

[0085] In addition, terms such as “unit,” “module,” etc., contained in the specification refer to units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof.

[0086] The flowchart described in the drawing figures can be executed by the controller or the processor. The order of operations in the flowchart can be changed, multiple operations can be combined, or each operation can be split, and a specific operation can be omitted. Furthermore, the operations in the flowchart can be executed sequentially, but not necessarily sequentially. For example, the order of operations can be changed, and at least two operations can be executed in parallel.

[0087] In the following, the fact that hardware parts are operatively coupled may include the fact that a direct and / or indirect connection is established between the hardware parts in a wired and / or wireless manner.

[0088] In an exemplary embodiment of the present disclosure, the vehicle may be described as being based on a concept that includes various means of transportation. In some cases, the vehicle may be designed to be based on a concept that includes not only various land transportation means such as cars, motorcycles, trucks, and buses traveling on roads, but also various means of transportation such as airplanes, drones, ships, etc.

[0089] For ease of explanation and for precise definition in the appended claims, the terms "upper," "lower," "inner," "outer," "top," "bottom," "upward," "downward," "front," "backward," "rearward," "inside," "outside," "inward," "outwardly," "internally," "externally," "internal," "external," "forward," and "backward" are used to describe features of the exemplary embodiments with reference to the positions of those features illustrated in the figures. The term "connect" or its derivatives refer to both direct and indirect connection.

[0090] The term "and / or" can include a combination of multiple related listed items or one of multiple related listed items. For example, "A and / or B" includes all three cases such as "A," "B," and "A and B."

[0091] In exemplary embodiments of the present disclosure, "at least one of A and B" may refer to "at least one of A or B" or to "at least one of combinations of at least one of A and B." Furthermore, "one or more of A and B" may refer to "one or more of A or B" or "one or more combinations of one or more of A and B."

[0092] In this description, unless otherwise stated, the singular includes the plural unless the context clearly indicates otherwise.

[0093] In the exemplary embodiment of the present disclosure, it is to be understood that a term such as "including" or "having" is intended to imply that the features, numbers, steps, acts, elements, parts, or combinations thereof described in the specification are present, and does not exclude the possibility that one or more other features, numbers, steps, acts, elements, parts, or combinations thereof are added or present.

[0094] According to an exemplary embodiment of the present disclosure, the components may be combined with each other to be implemented as a unit, or some components may be omitted.

[0095] The foregoing descriptions of specific exemplary embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the precise forms disclosed, and, of course, many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the present disclosure and their practical application to enable others skilled in the art to make and use various exemplary embodiments of the present disclosure, as well as various alternatives and modifications thereof. The scope of the present disclosure is intended to be defined by the appended claims and their equivalents.

Claims

[1] Motor drive device, comprising: a drive unit implemented as at least one power module with at least one switch and comprising an upper switch and a lower switch configured to drive a motor based on a motor drive mode, and a changeover switch configured to switch the motor drive mode; and a controller configured to determine a power loss of the upper switch, the lower switch, and the changeover switch based on the motor drive mode and an operating state of the motor to obtain a total power loss of the at least one power module, and to determine a temperature of the at least one power module based on the total power loss. [2] Motor drive device according to claim 1, wherein the upper switch is connected between a positive (+) electrode of a battery and one end of a winding contained in the motor, wherein the lower switch is connected between a negative (-) electrode of the battery and one end of the winding, and where the switch is connected between one end of the winding and a neutral end of the motor. [3] The motor drive device according to claim 1, wherein the controller is further configured to determine whether the operating state is a started state or a restricted state based on a rotational speed of the motor. [4] The motor drive device according to claim 1, wherein the motor drive mode comprises: a first drive mode in which the upper switch and the lower switch are turned off and the changeover switch is turned on to form a neutral point of the motor; and a second drive mode in which the upper and lower switches are switched complementarily to drive the motor and the changeover switch is off. [5] The motor drive device according to claim 4, wherein the controller is further configured to: to determine the power loss of the switch included in the total power loss in the first drive mode; and to determine the power loss of the upper switch and the lower switch included in the total power loss in the second drive mode. [6] Motor drive device according to claim 5, wherein the operating state of the engine in the first drive mode includes a start state and a restricted state, and wherein the control unit is further configured: to determine a transistor loss or a diode loss of the switch based on a maximum value of a sinusoidal current supplied to the switch in the started state; and to determine the transistor loss or the diode loss of the changeover switch from a phase current measurement of the motor in the de-energized state. [7] Motor drive device according to claim 5, wherein the operating state of the engine in the second drive mode includes a start state and a restricted state, and wherein the control unit is further configured: To determine transistor losses of the upper switch and the lower switch based on a maximum value of a sinusoidal current supplied to the upper switch and the lower switch in the started state and in a state where the motor is energized; Determining the diode losses of the upper switch and the lower switch from the maximum value in the started state and in a state in which energy is recovered from the motor; and Determining an upper switch transistor loss or a lower switch transistor loss from a phase current measurement of the motor in the restricted state. [8] The motor drive device according to claim 1, wherein the controller is further configured to: to determine a temperature variation of the at least one power module by multiplying the total power loss by a thermal resistance measurement value of the at least one power module; and to determine the temperature of the at least one power module by adding a coolant temperature of the at least one power module to the temperature fluctuation. [9] The motor driving device according to claim 8, wherein the temperature variation corresponds to a product of the total power loss, the thermal resistance measurement value and a coolant flow correction constant. [10] The engine driving apparatus according to claim 9, wherein a value of the coolant flow correction constant decreases with increasing coolant flow. [11] A method for determining a temperature of at least one power module comprising at least one switch in a drive unit implemented as the at least one power module and including an upper switch and a lower switch configured to drive a motor based on a motor drive mode, and a changeover switch configured to switch the motor drive mode, the method comprising: Determining a power loss of each of the upper switch, the lower switch, and the changeover switch based on the motor drive mode and an operating state of the motor to obtain a total power loss of the at least one power module; and Determining a temperature of the at least one power module based on the total power loss. [12] The method of claim 11, further comprising determining whether the operating state is a started state or a restricted state based on the speed of the engine. [13] The method of claim 11, wherein the motor drive mode comprises: a first drive mode in which the upper switch and the lower switch are turned off and the changeover switch is turned on to form a neutral point of the motor; and a second drive mode in which the upper and lower switches are switched complementarily to drive the motor and the changeover switch is off. [14] The method of claim 13, wherein determining the total power loss comprises: Determining the power loss of the switch included in the total power loss in the first drive mode; and Determine the power dissipation of the upper switch and the lower switch included in the total power dissipation in the second drive mode. [15] Method according to claim 14, wherein the operating state of the engine in the first drive mode includes a start state and a restricted state, and wherein determining the power loss of the switch comprises: Determining a transistor loss or a diode loss of the switch based on a maximum value of a sinusoidal current supplied to the switch in the started state; and Determine the transistor loss or the diode loss of the switch from a phase current measurement of the motor in the restricted state. [16] Method according to claim 14, wherein the operating state of the engine in the second drive mode includes a start state and a restricted state, and where the determination of the power losses of the upper switch and the lower switch includes: Determining the transistor losses of the upper switch and the lower switch from a maximum value of a sinusoidal current supplied to the upper switch and the lower switch in the started state and in a state in which power is supplied to the motor; Determining the diode losses of the upper switch and the lower switch using the maximum value in the started state and in a state in which energy is recovered from the motor; and Determining an upper switch transistor loss or a lower switch transistor loss from a phase current measurement of the motor in the restricted state. [17] The method of claim 11, wherein determining the temperature of the at least one power module comprises: Determining a temperature change of the at least one power module by multiplying the total power loss by a thermal resistance measurement of the at least one power module; and Determining the temperature of the at least one power module by adding a coolant temperature of the at least one power module to the temperature change. [18] The method of claim 17, wherein the temperature variation corresponds to a product of the total power dissipation, the thermal resistance measurement and a coolant flow correction constant. [19] The engine driving apparatus according to claim 18, wherein a value of the coolant flow correction constant decreases with increasing coolant flow.

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