Control method of inverter control unit

Abstract

To provide a control method of an inverter control unit capable of improving loss reduction effects as compared with a case where a switching speed is set based on only temperatures of a switching element.SOLUTION: A control method of an inverter control unit 100 includes: acquiring temperature information (element temperatures Tj1-Tj6) related to temperatures of a switching element 17 (step S14); acquiring a battery voltage Vdc of a battery 12 connected to the inverter control unit 100 (step S10); setting the switching speed of the switching element 17 based on the temperature information (element temperatures Tj1-Tj6) and the battery voltage Vdc (steps S24, S30, S32); and operating the switching element 17 at the switching speed having been set (step SB12).SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a control method for an inverter control device. [Background technology]

[0002] Patent Document 1 discloses a switching element driving method. A switching element driving device used in this switching element driving method includes a temperature sensor that detects the temperature of the switching element, and changes the switching speed of the switching element based on the temperature detection value detected by the temperature sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] WO2022 / 044298 Summary of the Invention [Problem to be solved by the invention]

[0004] In the switching element driving method described in Patent Document 1, the switching speed of the switching element is set based only on the temperature detection value. Therefore, the loss reduction effect obtained by changing the switching speed is limited, and further improvement in the loss reduction effect is required.

[0005] An object of the present invention is to provide a control method for an inverter control device that can improve the effect of reducing losses compared to a case in which the switching speed is set based only on the temperature of the switching elements. [Means for solving the problem]

[0006] A control method for an inverter control device according to one embodiment of the present invention is a control method including a switching element and a drive circuit for driving the switching element. The control method for the inverter control device acquires temperature information related to the temperature of the switching element, acquires a battery voltage of a battery connected to the inverter control device, and sets a switching speed of the switching element based on the temperature information and the battery voltage. The control method for the inverter control device then operates the switching element at the set switching speed. Effect of the Invention

[0007] According to an embodiment of the present invention, the switching speed of the switching element is set based on temperature information correlated with the withstand voltage of the switching element and the battery voltage that can be applied to the switching element. Therefore, the allowable surge voltage that can be generated in the switching element can be obtained from the difference between the withstand voltage and the battery voltage, so that the switching speed can be set to a high speed within a range in which the surge voltage that can be generated in the switching element does not exceed the allowable surge voltage.

[0008] Therefore, compared to the case where the switching speed is set based only on the temperature of the switching element, it is possible to improve the effect of reducing losses. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating the configuration of an electric motor control system including an inverter control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram showing a configuration of a main part of the inverter control device. [Diagram 3] FIG. 3 is a block diagram illustrating functions for executing the control method of the inverter control device in the controller. [Figure 4] FIG. 4 is a flowchart of the inverter control process. [Diagram 5] FIG. 5 is a flowchart continuing from FIG. [Figure 6]FIG. 6 is a flowchart continuing from FIG. [Figure 7] FIG. 7 is a flowchart of the switching process. [Figure 8] FIG. 8 is an explanatory diagram showing the operation of the inverter control process. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] 1 is a diagram illustrating the configuration of an electric motor control system 1 including an inverter control device 100 according to this embodiment. The electric motor control system 1 including the inverter control device 100 is installed in, for example, a vehicle, and controls a motor 20 that drives the vehicle.

[0012] As shown in FIG. 1, the motor control system 1 mainly includes a battery 12 as a DC power supply, an inverter control device 100, and a motor 20 configured as, for example, an on-vehicle three-phase AC motor.

[0013] In particular, the inverter control device 100 of this embodiment is configured as a power converter that adjusts the power supplied from the battery 12 to the motor 20 (or the regenerative power from the motor 20 to the battery 12). More specifically, the inverter control device 100 performs power conversion from DC to three-phase AC or from three-phase AC to DC between the battery 12 and the motor 20.

[0014] The inverter control device 100 includes a smoothing capacitor 14 for suppressing ripples, a plurality of (six in the figure) power semiconductor element units 16-1 to 16-6 constituting a switching circuit, and a drive circuit 30 for driving the power semiconductor element units 16. The plurality of power semiconductor element units 16-1 to 16-6 constitute an element module. The inverter control device 100 also includes a cooler 40, a controller 50 as a control unit, and a battery voltage V dc and a voltage sensor 13 for detecting the voltage.

[0015] The power semiconductor element units 16-1 to 16-6 are configured with three-phase six arms, that is, upper arms UP, VP, and WP and lower arms UN, VN, and WN in each of the three phases UVW. The power semiconductor element units 16-1 to 16-6 also include voltage-controlled switching elements 17-1 to 17-6 configured with semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors). The power semiconductor element units 16-1 to 16-6 also include freewheel diodes 18-1 to 18-6 that pass a freewheel current from the motor 20 when the switching elements 17-1 to 17-6 are turned off. The switching elements 17-1 to 17-6 convert DC power to AC power and also convert AC power to DC power.

[0016] The power semiconductor element units 16-1 to 16-6 are provided with temperature detection diodes 19-1 to 19-6 that function as temperature sensors, respectively. The temperature detection diodes 19-1 to 19-6 acquire the temperatures of the corresponding switching elements 17-1 to 17-6. As a result, the temperature detection diodes 19-1 to 19-6 acquire temperature information related to the temperatures of the corresponding switching elements 17-1 to 17-6.

[0017] The power semiconductor element units 16-1 to 16-3 are provided with current sensors 15-1 to 15-3, respectively. The current sensors 15-1 to 15-3 detect collector currents I C In this way, each of current sensors 15-1 to 15-3 detects the current flowing through corresponding switching elements 17-1 to 17-3.

[0018] The driving circuit 30 is connected in parallel to each of the switching elements 17-1 to 17-6. The driving circuit 30 receives a PWM (Pulse Width Modulation) signal and a speed switching signal S input from the controller 50. swBased on this, each switching element 17 is driven (ON / OFF). Through this switching operation, when the motor 20 is in power running, the DC power from the battery 12 is converted into the desired AC power and supplied to the motor 20. On the other hand, when the motor 20 is in regeneration, the rotational energy of the motor 20 is converted into DC power and supplied to the battery 12.

[0019] The drive circuit 30 also detects the VF voltage V f1 ~V f6 The element temperature T j1 ~T j6 The drive circuit 30 detects the element temperature T j1 ~T j6 is output to the controller 50.

[0020] The cooler 40 cools the power semiconductor element section 16. The cooler 40 is configured, for example, by a water jacket for supplying cooling water to the power semiconductor element section 16 to cool it. The cooler 40 is also provided with a cooling water temperature sensor 41 for detecting the temperature of the cooling water. The cooling water temperature sensor 41 for detecting the temperature of the cooling water in the cooler 40 detects, for example, the average temperature of each of the switching elements 17-1 to 17-6.

[0021] The controller 50 includes a central processing unit (CPU), a read only memory (ROM), a random access memory (RAM), and an input / output interface (I / O interface). The controller 50 is configured with a computer programmed to execute each process described below. The controller 50 can also be configured with multiple computer hardware that executes each process in a distributed manner.

[0022] The controller 50 receives the required torque of the motor 20, which is an electric load, as an input and generates a PWM signal for defining the switching pattern (duty ratio) of each switching element 17. More specifically, the controller 50 calculates a target supply power (voltage command value) to the motor 20 so as to realize a desired required torque according to an external required load (such as the amount of operation of the accelerator pedal in the case of a vehicle). Then, the controller 50 generates a PWM signal so as to realize the calculated voltage command value.

[0023] The controller 50 also receives the element temperature T j1 ~T j6 and the battery voltage V from the voltage sensor 13 dc In more detail, the controller 50 executes the inverter control process using the element temperature T j1 ~T j6 and the battery voltage V dc and sets the switching speed of all switching elements 17-1 to 17-6 to a high-speed mode, a medium-speed mode, or a low-speed mode, which will be described later.

[0024] The controller 50 then outputs a speed switching signal S to instruct the drive circuit 30 to drive all of the switching elements 17-1 to 17-6 at a switching speed corresponding to the set mode. sw As a result, the controller 50 generates the speed switching signal S sw The operation of each of the switching elements 17-1 to 17-6 is controlled via a drive circuit 30 to which the signal is sent.

[0025] The controller 50 also sets a dead time indicating the time when the switching elements 17-1, 17-2, 17-3 of the upper arms UP, VP, WP and the switching elements 17-4, 7-5, 17-6 of the lower arms UN, VN, WN are simultaneously turned off. Setting this dead time may cause a dead time error between the PWM signal, which is a command value, and the output signal. For this reason, the controller 50 sets a dead time compensation value to compensate for the dead time error. At this time, the controller 50 sets the dead time compensation value according to the switching speed of the set mode.

[0026] The controller 50 corrects the generated PWM signal based on the set dead-time compensation value so as to realize the voltage command value. As a result, the controller 50 generates a PWM signal incorporating the dead-time compensation value to instruct the drive circuit 30 to drive each of the switching elements 17-1 to 17-6 according to the signal incorporating the dead-time compensation value.

[0027] The controller 50 controls the operation of each of the switching elements 17-1 to 17-6 via the drive circuit 30 to which the PWM signal incorporating the dead time compensation value is sent. As a result, the controller 50 controls each of the switching elements 17-1 to 17-6 so that the output signal from the inverter control device 100 approaches the PWM signal generated to realize the voltage command value (see, for example, Japanese Patent No. 4760118).

[0028] The inverter control process will be described in detail later. The configuration of the inverter control device 100 will be described in further detail below.

[0029] Fig. 2 is a diagram illustrating a configuration of a main part of the inverter control device 100. For simplification, Fig. 2 shows only a connection portion between the drive circuit 30 and one power semiconductor element unit 16. However, in this embodiment, all of the power semiconductor element units 16-1 to 16-6 are connected to the drive circuit 30 in the manner shown in Fig. 2.

[0030] The controller 50 detects the element temperature T j (T j1 ~T j6 ) is input to the controller 50. The controller 50 also receives the battery voltage V dc and the collector current I from the current sensor 15. C (I C1 ~I C3 ) and are the inputs.

[0031] The controller 50 then generates a speed switching signal S from these input values. sw and generates the speed switching signal S sw is output to the gate drive IC 30a.

[0032] The gate driver IC 30a of the driver circuit 30 receives a speed switching signal S sw is used as an input, and the gate resistance R of the switching element 17 g (R g1 , R g2 , R g3 ) is set. The gate driver IC 30a then transmits a control signal based on the PWM signal to the set gate resistor R g The signal is output from the output ports out1 to out3 to which it is connected.

[0033] More specifically, the gate driver IC 30a receives a speed switching signal S sw With reference to the above, the gate resistance R of the switching element 17 g This switches the gate resistance R of the switching element 17. g is the first gate resistor R g1 and a second gate resistor R g2 and the third gate resistor R g3 You can switch between and.

[0034] Here, the gate resistance R g The first gate resistance R g1When the first gate resistor R g1 can be rephrased as efficiency-priority gate resistance.

[0035] In addition, the gate resistance R g The relatively high third gate resistor R g3 , the switching speed becomes relatively slow, suppressing the surge voltage generated in the switching element 17 and contributing to the protection of the switching element 17. g3 can be rephrased as a voltage protection priority gate resistance.

[0036] And the gate resistor R g The second gate resistor R g2 When the second gate resistor R is set to 1, the switching speed is a medium speed, which is higher than the low speed and lower than the high speed. This suppresses the loss that occurs during switching, and protects the switching element 17 by suppressing the surge voltage. g2 can be rephrased as a balanced gate resistance.

[0037] More specifically, the gate resistance R of the switching element 17 g The larger the gate resistance R of the switching element 17, the smaller the gate current that charges and discharges the capacitance of the switching element 17, and the slower the switching speed. g The smaller is set, the larger the gate current will be, and therefore the faster the switching speed will be.

[0038] As a result, the gate resistance R g The first gate resistance R is relatively low g1 When the gate resistor R g The third gate resistance R is relatively high. g3 When the gate resistor R g A medium second gate resistor Rg2 When this is set, the control mode becomes the medium speed mode.

[0039] Furthermore, as can be seen from FIG. 2, the gate driving IC 30a provides the same gate resistance R g Therefore, the gate driving IC 30a is configured to set the first gate resistance R g1 , second gate resistor R g2 , or the third gate resistor R g3 That is, the gate driving IC 30a drives all of the power semiconductor element units 16-1 to 16-6 so as to simultaneously switch their switching speeds to low speed, medium speed, or high speed.

[0040] Therefore, the inverter control device 100 of this embodiment adjusts the switching speeds of all the power semiconductor element units 16-1 to 16-6 collectively using one drive circuit 30. That is, it is possible to adjust all of the switching speeds of the power semiconductor element units 16-1 to 16-6 without providing a drive circuit for each of them. This simplifies the circuit configuration and prevents the device from becoming larger in size.

[0041] The gate driving IC 30a of the driving circuit 30 generates a control signal based on the PWM signal sent from the controller 50. The gate driving IC 30a of the driving circuit 30 transmits the generated control signal to a set gate resistor R g The signal is output from the output ports out1 to out3 to which it is connected.

[0042] Specifically, the gate driver IC 30a generates a control signal based on a PWM signal that takes into account the dead time compensation value, and transmits the control signal to a set gate resistor R g The switching elements 17-1 to 17-6 are driven by outputting from the output ports out1 to out3 to which the signals are connected.

[0043] Next, the processing in the controller 50 (particularly, the speed switching signal S sw The process related to the generation of

[0044] FIG. 3 is a block diagram illustrating the functions of the controller 50 for executing the control method of the inverter control device 100.

[0045] 3, the controller 50 includes a minimum value calculation unit 52, a switching signal generation unit 54, and a dead time compensation value setting unit 56 that sets a dead time compensation value. j1 ~T j6 The lowest value among these is the element temperature T j and outputs the result to the switching signal generating unit 54.

[0046] The switching signal generating unit 54 receives the element temperature T j and the battery voltage V from the voltage sensor 13 dc and the collector current I from the current sensor 15. C And enter.

[0047] The switching signal generating unit 54 also detects the element temperature T j and the battery voltage V dc Based on the above, it is determined whether the control mode should be set to the high speed mode, the medium speed mode, or the low speed mode. j constitutes temperature information related to the temperature of the switching element 17. The high-speed mode is a mode in which the switching speed is relatively high. The medium-speed mode is a mode in which the switching speed is medium. The low-speed mode is a mode in which the switching speed is relatively low.

[0048] Then, the switching signal generating unit 54 selects an appropriate gate resistance R g Speed ​​change signal S including the command to set sw Generate.

[0049] Generally, it is known that the withstand voltage (voltage resistance) of semiconductor switching elements tends to have a positive slope with respect to temperature. Therefore, the switching speed of the semiconductor switching elements can be made relatively high at high temperatures, and increasing the switching speed reduces element losses due to switching.

[0050] On the other hand, the collector current I C It is known that the larger the collector current I, the larger the surge voltage that occurs. C As the surge voltage increases, the surge voltage generated in the semiconductor switching element and the battery voltage V dc The switching speed is set so that the sum of these does not exceed the withstand voltage of the semiconductor switching element.

[0051] Here, the collector current I C The relationship between the collector current I and the surge voltage generated differs for each switching speed. Therefore, the collector current I detected using the speed-specific current surge characteristics corresponding to the switching speed to be changed is C The surge voltage generated from the estimated surge voltage ΔV S and the battery voltage V dc The switching speed is set so that the sum of these does not exceed the withstand voltage.

[0052] The speed-specific current surge characteristics are stored in advance in a read-only memory (ROM) of the controller 50.

[0053] This current surge characteristic by speed shows the collector current I C Surge current characteristics for low speed F_R showing the relationship between g3 (I C ) (see Figure 8). The current surge characteristics by speed also include the collector current I C Current surge characteristics for medium speed F_R showing the relationship between g2(I C ) (see Figure 8). In addition, the current surge characteristics by speed include the high-speed current surge characteristics F_R, which show the relationship between the collector current IC and surge voltage when the switching speed is set to the high-speed specified switching speed. g1 (I C ) (see Figure 8).

[0054] Next, the inverter control process will be described in further detail.

[0055] Fig. 4 is a flowchart for explaining the inverter control process. Fig. 5 is a flowchart continuing from Fig. 4. Fig. 6 is a flowchart continuing from Fig. 4. Fig. 7 is a flowchart of the switching process. Fig. 8 is an explanatory diagram showing the operation of the inverter control process. In this embodiment, the controller 50 repeatedly executes the inverter control processes shown in Figs. 4 to 7 at predetermined calculation cycles.

[0056] First, in step S10, the controller 50 detects the battery voltage V dc In step S12, the battery voltage V dc Here, it is determined whether the battery voltage V dc When the battery 12 whose voltage fluctuates in the range of 240 V to 400 V is used, the first threshold value th_1 is set to, for example, 350 V. The determination in step S12 may be made based on the remaining battery charge information SOC of the battery 12.

[0057] The controller 50 controls the battery voltage V dc If it is determined that the battery voltage V exceeds the first threshold th_1, the process proceeds to step S14. dc If it is determined that the first threshold value th_1 or less, the process proceeds to step S40.

[0058] In this embodiment, the battery voltage V dcIn the above example, the process proceeds to step S40 when it is determined that the battery voltage V is equal to or less than the first threshold th_1. However, the present embodiment is not limited to this. dc When it is determined that the first threshold value th_1 or less, the controller 50 proceeds to the process of step S48 and resets the R g The flag is connected to the first gate resistor R g1 R indicates g1 may be set to

[0059] Next, in step S14, the controller 50 receives temperature information (element temperature T j ) is input, and in step S16, the element withstand voltage V break Calculate the following.

[0060] In this embodiment, the temperature information is the element temperature T j The controller 50 uses the element temperature T j and cooling water temperature T w The average value of the cooling water temperature T w Only the above may be used.

[0061] Specifically, the element breakdown voltage V break As mentioned above, the temperature information is the element temperature T j has a positive slope with respect to V break =F(T j )=A×T j +B, where A and B are constants and A indicates the slope. For this reason, the controller 50 break =F(T j )=A×T j Using the formula +B, the element breakdown voltage V break Calculate the following.

[0062] In step S18, the controller 50 determines the element withstand voltage V break The battery voltage V applied to the switching element 17 fromdc By subtracting the above, the allowable surge voltage ΔV that can be applied to the switching element 17 is obtained. S′ Calculate the following.

[0063] As a result, as shown in FIG. 8, the controller 50 controls the element temperature T j The breakdown voltage V calculated from break and the battery voltage V dc The allowable surge voltage ΔV changes based on S′ Calculate the following.

[0064] In step S20, the controller 50 detects the collector current I C1 ~I C3 Then, the controller 50 inputs the collector current I C1 ~I C3 For example, the largest current value is used in the following calculations. C Let us assume that.

[0065] In step S22, the controller 50 calculates an estimated surge voltage ΔV that may occur in the switching element 17 when the switching speed is high. S (ΔV S _R g1 ) is the allowable surge voltage ΔV S′ Determine whether it is equal to or less than the above.

[0066] Specifically, the controller 50 determines the high-speed current surge characteristic F_R g1 (I C ) The collector current I C The estimated surge voltage ΔV that may occur in the switching element 17 in the case S (ΔV S _R g1 ) is calculated. g1 (I C ) is the collector current I C The controller 50 calculates the estimated surge voltage ΔV S (ΔVS _R g1 ) is the allowable surge voltage ΔV S′ It is determined whether the image fits within the range.

[0067] Estimated surge voltage ΔV S is the allowable surge voltage ΔV S′ In the following cases, in step S24, the controller 50 g The flag is connected to the first gate resistor R g1 R indicates g1 Then, the process proceeds to step S26. S is the allowable surge voltage ΔV S′ If it exceeds this limit, the controller 50 proceeds to the process of step S28.

[0068] Referring to Figure 8, the high-speed current surge characteristic F_R g1 (I C ) collector current I C The estimated surge voltage ΔV indicated by position P1 S is the allowable surge voltage ΔV S′ It is judged whether the estimated surge voltage ΔV S (ΔV S _R g1 ) is the allowable surge voltage ΔV S′ If the switching speed exceeds F_R, the medium speed current surge characteristic F_R is used to reduce the switching speed. g2 (I C ) is used to make the judgment.

[0069] In step S28, the controller 50 calculates an estimated surge voltage ΔV that may occur in the switching element 17 when the switching speed is medium. S (ΔV S _R g2 ) is the allowable surge voltage ΔV S′ Determine whether it is equal to or less than the above.

[0070] Specifically, the controller 50 determines the medium speed current surge characteristic F_R g2 (I C ) to obtain the collector current I CThe estimated surge voltage ΔV that may occur in the switching element 17 in the case S (ΔV S _R g2 ) is calculated. g2 (I C ) is the collector current I when the switching speed is medium C The controller 50 calculates the estimated surge voltage ΔV S (ΔV S _R g2 ) is the allowable surge voltage ΔV S′ It is determined whether the image fits within the range.

[0071] Referring to Figure 8, the medium-speed current surge characteristic F_R g2 (I C ) collector current I C The estimated surge voltage ΔV indicated by position P2 S is the allowable surge voltage ΔV S′ In FIG. 8, the estimated surge voltage ΔVS (ΔV S _R g2 ) does not exceed the allowable surge voltage ΔVS', processing is performed to make the switching speed medium.

[0072] In step S28, the estimated surge voltage ΔV S is the allowable surge voltage ΔV S′ In the following cases, in step S30, the controller 50 g The flag is connected to the second gate resistor R g2 R indicates g2 Then, the process proceeds to step S26. On the other hand, in step S28, the estimated surge voltage ΔV S is the allowable surge voltage ΔV S′ If R exceeds R , in step S32, the controller 50 adjusts R g The flag is connected to the third gate resistor R g3 R indicates g3 Then, the process proceeds to step S26.

[0073] In this way, the controller 50 calculates the speed-specific current surge characteristic (F_Rg1 (I C ), F_R g2 (I C ), F_R g3 (I C )) and the collector current I as the through current C Estimated surge voltage ΔV based on S The controller 50 also calculates the estimated surge voltage ΔV S is the allowable surge voltage ΔV S′ The determination of whether the specified switching speed falls within the range of F_R g1 (I C ), medium-speed current surge characteristics F_R g2 (I C ) in this order. As a result, the controller 50 S′ The estimated surge voltage ΔV falls within the range S The switching speed is set based on the specified switching speed of the current surge characteristic having the highest switching speed among the calculated speed-specific current surge characteristics.

[0074] In this embodiment, the speed-specific current surge characteristics are represented by the current surge characteristics F_R g1 (I C ), F_R g2 (I C ), F_R g3 (I C ) is stored in the storage device 100, but the present embodiment is not limited to this. S is the allowable surge voltage ΔV S′ If it is determined that the difference exceeds R g The flag is connected to the third gate resistor R g3 R indicates g3 For this reason, the controller 50 sets the low-speed current surge characteristic F_R g3 (I C ) may not be memorized.

[0075] In step S12 described above, the battery voltage V dcIf it is determined that the torque information T is equal to or smaller than the first threshold value th_1, then in step S40, the controller 50 acquires the torque information T, and the process proceeds to step S42.

[0076] The torque information T may be, for example, a command value of a required torque set by the controller 50 when specifying the torque of the motor 20 in accordance with the amount of operation of an accelerator pedal provided in the vehicle. In addition, the torque information T may be, for example, a collector current I C The torque information T consisting of these data indicates "0" or a positive value when the motor 20 is in a powering state where the motor 20 generates or does not generate torque, and indicates a negative value when the motor 20 is in a regenerative state, for example, where the motor 20 receives torque.

[0077] In step S42, the controller 50 determines whether the acquired torque information T is equal to or greater than "0". If the torque information T is less than "0" in step S42, the motor 20 is in a regenerative state in which it receives torque from the outside. Therefore, in step S44, the controller 50 g The flag is connected to the second gate resistor R g2 R indicates g2 The switching speed of the switching element 17 is set to medium speed, and the process proceeds to step S26.

[0078] If the torque information T is equal to or greater than "0" in step S42, the motor 20 is in a powering state in which it generates torque, and therefore the controller 50 proceeds to the process of step S46.

[0079] In step S46, the input battery voltage V dc Here, it is determined whether the battery voltage V dc However, in this embodiment where the voltage varies in the range of 240V to 400V, the second threshold th_2 is set to, for example, 300V, which is lower than the first threshold th_1. This second threshold th_2 is set to a value that is lower than the surge voltage and the battery voltage V dc The sum of these is the breakdown voltage V of the switching element 17.break A low enough battery voltage that does not exceed V dc The determination in step S46 may be made based on the remaining battery charge information SOC of the battery 12.

[0080] The controller 50 controls the battery voltage V dc If it is determined that the battery voltage V exceeds the second threshold th_2, the process proceeds to step S44, and the switching speed of the switching element 17 is set to medium speed. dc is equal to or smaller than the second threshold th_2, in step S48, the controller 50 g The flag is connected to the first gate resistor R g1 R indicates g1 As a result, the controller 50 increases the switching speed of the switching element 17 and proceeds to the process of step S26.

[0081] In the process of step S26, the controller 50 executes a switching process (see FIG. 7).

[0082] In step SB10 of the switching process, the controller 50 g The dead time compensation value is switched according to the flag.

[0083] Thereby, the dead time compensation value is switched according to the switching speed of the switching element 17.

[0084] In step SB12, the controller 50 g In response to the flag, the gate resistance R g Switch between.

[0085] Specifically, the controller 50 determines the selected gate resistance R g The speed switching signal S is output to the drive circuit 30 to specify sw , R g Switch based on what's set in the flag.

[0086] Then, the speed change signal S sw The gate driver IC 30a of the driver circuit 30 receives the PWM signal, corrects the dead time compensation value, and outputs the corrected control signal as the speed switching signal S sw The gate resistance R g The signal is output from the output ports out1 to out3 to which it is connected.

[0087] As a result, the switching element 17 operates based on the PWM signal corrected by the dead time compensation value, and the gate resistor R g It operates at a switching speed according to the

[0088] Then, the controller 50 returns to the main routine via the inverter control process to perform the next process.

[0089] According to the switching element driving method of the present embodiment described above, the following advantageous effects are achieved.

[0090] According to the present embodiment, a control method for an inverter control device 100 including a switching element 17 and a drive circuit 30 for driving the switching element 17 is provided. In the control method for the inverter control device 100, temperature information related to the temperature of the switching element 17 (element temperature T j , cooling water temperature T w In the control method of the inverter control device 100, the battery voltage V dc In the control method of the inverter control device 100, temperature information (element temperature T j , cooling water temperature T w ) and battery voltage V dc The switching speed of the switching element 17 is set based on this (steps S24, S30, S32). In the control method of the inverter control device 100, the switching element 17 is operated at the set switching speed (step SB12).

[0091] As a result, the switching speed of the switching element 17 is determined based on temperature information (element temperature T j , cooling water temperature T w ) and the battery voltage V that can be applied to the switching element 17 dc It is set based on.

[0092] Here, the allowable surge voltage ΔV that can be generated in the switching element 17 is S′ is the withstand voltage and battery voltage V dc Therefore, the surge voltage that can occur in the switching element 17 is equal to the permissible surge voltage ΔV S′ It is possible to set the switching speed to a high speed within a range not exceeding .

[0093] Therefore, compared to the case where the switching speed is set based only on the temperature of the switching element 17, it is possible to improve the effect of reducing losses.

[0094] In addition, in the control method of the inverter control device 100 of the present embodiment, the temperature information (element temperature T j , cooling water temperature T w ) based on the switching element 17 as the element withstand voltage V break (Step S16). In the control method of the inverter control device 100, the element withstand voltage V break and battery voltage V dc The allowable surge voltage ΔV that can be applied to the switching element 17 based on S′ In the control method of the inverter control device 100, the allowable surge voltage ΔV S′ The switching speed is set based on this (steps S24, S30, S32).

[0095] That is, the withstand voltage of the switching element 17 changes depending on the temperature. j , cooling water temperature T w ) the breakdown voltage V break In addition, the breakdown voltage V breakto battery voltage V of battery 12 dc By subtracting the allowable surge voltage ΔV S′ Therefore, the surge voltage that can occur is the allowable surge voltage ΔV S′ Therefore, the switching speed can be set high within a range not exceeding 100%, and the loss reduction effect can be enhanced.

[0096] In addition, in the control method of the inverter control device 100 of this embodiment, a speed-specific current surge characteristic (F_R g1 (I C ), F_R g2 (I C ), F_R g3 (I C )) and the flow current (I C ) and the estimated surge voltage ΔV S (Steps S22 and S28). In the control method of the inverter control device 100, the allowable surge voltage ΔV S′ The estimated surge voltage ΔV falls within the range S The calculated speed-specific surge current characteristics (F_R g1 (I C ), F_R g2 (I C ), F_R g3 (I C )) with the highest switching speed (F_R g1 (I C ), F_R g2 (I C ), F_R g3 (I C Based on the specified switching speed (high speed, medium speed, low speed) of the inverter (steps S22, S28), the switching speed is set (steps S24, S30, S32).

[0097] That is, the surge voltage that occurs is determined by the rate of change of current associated with the switching speed and the inductance of the coil of the motor 20. For this reason, the flow current (I C ) and surge voltage. g1 (I C ), F_R g2 (I C ), F_R g3 (I C )) and the flow current (I C ) and estimate the surge voltage that occurs by surge voltage ΔV S It can be estimated as:

[0098] This results in an estimated surge voltage ΔV S This improves the estimation accuracy, which makes it possible to further increase the loss reduction effect. S The calculation speed can be increased compared to the case where

[0099] In addition, in the control method of the inverter control device 100 of this embodiment, the dead-time compensation value that compensates for the dead-time of the switching elements 17 that constitute the upper arms UP, VP, WP and the switching elements 17 that constitute the lower arms UN, VN, WN is changed in accordance with the change in switching speed (step SB10).

[0100] That is, since the dead time compensation value is changed in accordance with the change in the switching speed, it is possible to suppress the voltage control error compared to the case where the dead time compensation value is not changed even when the switching speed is changed. Also, the switching speed and collector current I C , and the battery voltage V dc Based on this, it is possible to suppress an increase in the voltage control error.

[0101] In the control method of the inverter control device 100 of this embodiment, the switching speed of the switching element 17 is selectively set from a relatively high speed (step S24), a relatively low speed (step S32), or a medium speed (step S30) that is higher than the low speed and lower than the high speed. dc If the temperature information (element temperature T j , cooling water temperature T w ), the switching speed is set to high (S48 via steps S40, S42, and S46).

[0102] That is, the battery voltage V dc When the allowable surge voltage ΔV S′ The battery voltage V dc When the first threshold th_1 or less is reached, even if the switching speed is set to a high speed, the surge voltage generated in the switching element 17 is equal to or lower than the allowable surge voltage ΔV S′ will be smaller than

[0103] Therefore, the battery voltage V dc When the temperature information (element temperature T j , cooling water temperature T w By setting the switching speed to a high speed, it is possible to omit unnecessary processing, thereby reducing the load on the controller 50 and achieving a loss reduction effect.

[0104] The control method of the inverter control device 100 of this embodiment is a control method for controlling the motor 20 mounted on a vehicle and driving the vehicle. dc is equal to or smaller than the first threshold value th_1 (step S22) and the torque information T relating to the torque output from the motor 20 indicates a powering state (step S42). dcis equal to or smaller than a second threshold th_2 which is smaller than the first threshold th_1 (step S46), the switching speed is set to high speed (step S48).

[0105] That is, the allowable surge voltage ΔV S′ is the battery voltage V dc Varies depending on the allowable surge voltage ΔV S′ is the battery voltage V dc is small when the battery voltage V dc is low.

[0106] Therefore, when the vehicle is in a powered state and the battery voltage V dc is equal to or less than a second threshold th_2 which is smaller than the first threshold th_1, the switching speed is increased, thereby making it possible to obtain a loss reduction effect while reducing the load on the controller 50. This enables control according to the running state of the vehicle.

[0107] In addition, in the control method of the inverter control device 100 of this embodiment, when the torque information T indicates a regenerative state (step S42), the temperature information (element temperature T j , cooling water temperature T w ), the switching speed is set to medium speed (step S44).

[0108] As a result, when the vehicle is in a regenerative state, it is possible to achieve a well-balanced control between suppressing losses that occur during switching and protecting the switching element 17 while reducing the load on the controller 50.

[0109] In addition, the control method of the inverter control device 100 of this embodiment is a method in which the torque information T indicates a powering state (step S42) and the battery voltage V dc is higher than the second threshold th_2 (step S46), the temperature information (element temperature T j , cooling water temperature T w ), the switching speed is set to medium speed (step S44).

[0110] As a result, when the vehicle is in a powered state, it is possible to achieve a well-balanced control between suppressing losses that occur during switching and protecting the switching element 17 while reducing the load on the controller 50.

[0111] Although the embodiments of the present invention have been described above, the above-described embodiments merely illustrate some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above-described embodiments.

[0112] For example, in the above embodiment, the case where the temperature detection diodes 19-1 to 19-6 are provided in all the power semiconductor element units 16-1 to 16-6, respectively, has been described as an example. However, instead of this, the present embodiment may employ a configuration in which the temperature detection diodes 19 are provided in only some of the power semiconductor element units 16-1 to 16-6.

[0113] In the above embodiment, the gate resistance R g However, in this embodiment, any manipulated variable capable of manipulating the switching speed of the switching element 17, such as a gate voltage, may be used instead of or in addition to this. [Explanation of symbols]

[0114] 12 Battery 13 Voltage Sensor 15 Current Sensor 17 Switching elements 20 Motor 30 Drive circuit 41 Coolant temperature sensor 50 Controller 54 Switching signal generator 56 Dead time compensation value setting section I C Collector Current F_R g1 (I C ) High-speed current surge characteristics F_R g2 (IC ) Medium speed current surge characteristics F_R g3 (I C ) Low speed current surge characteristics T Torque Information T j Element Temperature T w cooling water temperature UN Lower Arm UP Upper arm ΔV S Estimated surge voltage ΔV S′ Permissible surge voltage V dc Battery voltage V break Element breakdown voltage th_1 First threshold th_2 Second threshold

Claims

1. A control method for an inverter control device including a switching element and a drive circuit for driving the switching element, comprising: acquiring temperature information relating to a temperature of the switching element; A battery voltage of a battery connected to the inverter control device is acquired. setting a switching speed of the switching element based on the temperature information and the battery voltage; operating the switching element at the set switching speed; A control method for an inverter control device.

2. A control method for an inverter control device according to claim 1, Calculating a withstand voltage of the switching element based on the temperature information; calculating an allowable surge voltage that can be applied to the switching element based on the element withstand voltage and the battery voltage; setting the switching speed based on the allowable surge voltage; A control method for an inverter control device.

3. A control method for an inverter control device according to claim 2, comprising: Calculating an estimated surge voltage based on a speed-specific current surge characteristic, which is a characteristic determined for each of a plurality of specified switching speeds and indicates a relationship between a flowing current and a generated surge voltage, and based on the flowing current of the switching element; setting the switching speed based on the specified switching speed of the speed-specific current surge characteristic having the highest switching speed among the speed-specific current surge characteristics for which the estimated surge voltage falling within the range of the allowable surge voltage has been calculated; A control method for an inverter control device.

4. A control method for an inverter control device according to claim 3, comprising the steps of: a dead time compensation value for compensating for dead times of the switching elements constituting the upper arm and the switching elements constituting the lower arm is changed in accordance with the change in the switching speed; A control method for an inverter control device.

5. A control method for an inverter control device according to claim 4, comprising the steps of: The switching speed of the switching element is selectively set from a high speed, which is a relatively high speed, a low speed, which is a relatively low speed, or a medium speed, which is a speed higher than the low speed and lower than the high speed, When the battery voltage is equal to or lower than a first threshold value, the switching speed is set to the high speed regardless of the temperature information. A control method for an inverter control device.

6. 6. A control method for an inverter control device according to claim 5, which is a control method for controlling a motor mounted on a vehicle and driving the vehicle, When the battery voltage is equal to or lower than the first threshold and torque information regarding the torque output from the motor indicates a powering state, the switching speed is set to the high speed when the battery voltage is equal to or lower than a second threshold which is lower than the first threshold. A control method for an inverter control device.

7. A control method for an inverter control device according to claim 6, comprising the steps of: When the torque information indicates a regenerative state, the switching speed is set to the medium speed regardless of the temperature information. A control method for an inverter control device.

8. A control method for an inverter control device according to claim 6, comprising the steps of: When the torque information indicates a powering state and the battery voltage is higher than the second threshold value, the switching speed is set to the medium speed regardless of the temperature information. A control method for an inverter control device.

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