Motor control device

Abstract

The motor control device (10) is configured to generate an application voltage for application to the motor in a manner that the approach speed of the actual motor rotation speed (ω) that has decreased in accordance with the decrease in the power supply voltage (V DC ) approaches the target motor rotation speed (ω ＊ ) gradually becomes higher and then gradually decreases in the case where the power supply voltage (V DC ) turns to rise, and to perform variation suppression control by applying the generated application voltage to the motor.

Description

[0001] Cross-references to related applications

[0002] This application is based on Japanese Patent Application No. 2020-131926 filed on August 3, 2020, and references the contents of the base application in its entirety by way of reference. Technical Field

[0003] This disclosure relates to a motor control device that performs variation suppression control to prevent the motor speed from following the variation of the power supply voltage when the power supply voltage supplied from the power source for driving the motor temporarily decreases, then rises and returns to the normal power supply voltage. Background Technology

[0004] For example, Patent Document 1 discloses a method for operating an electric fan in a vehicle. According to this method, when the drive voltage of the motor that rotates the electric fan changes (decreases), the motor speed is adjusted to a desired speed lower than the desired speed when there is no voltage change. This lower desired speed is maintained until the drive voltage recovers from its decrease. Furthermore, after a predetermined time has elapsed after the drive voltage has recovered to a certain level, the desired speed continuously and linearly increases from the lower desired speed back to the original speed.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: US Patent No. 9667185 Summary of the Invention

[0008] According to the technology in the aforementioned Patent Document 1, when the drive voltage changes, the motor speed is adjusted to a lower speed than the desired speed when there is no voltage change. Therefore, it is possible to prevent the motor speed from changing in a manner that follows the change in drive voltage.

[0009] However, in the technology of Patent Document 1, during the period of driving voltage fluctuation (reduction), the motor speed is maintained at a low desired speed as a certain value, and after a predetermined time has elapsed after the power supply voltage recovers to a certain level, it linearly increases to the original desired speed from that point in time. Therefore, the change in motor speed occurs suddenly, which may cause discomfort to the occupants of the vehicle.

[0010] This disclosure is made in view of the foregoing points, and its object is to provide a motor control device that can suppress fluctuations in the motor speed without causing discomfort to the occupants of a vehicle when the power supply voltage used to drive the motor changes.

[0011] To achieve the above objective, the motor control device of this disclosure performs variation suppression control to prevent the motor speed from following the variation of the power supply voltage when the power supply voltage supplied from the power source for driving the motor temporarily decreases, then rises and returns to the normal power supply voltage. Its configuration includes:

[0012] The detection department detects a decrease in power supply voltage, which then increases; and

[0013] The generation unit, based on the detection unit's finding that the power supply voltage is rising, generates an applied voltage for the motor using a prescribed function, such that the actual motor speed, which decreases as the power supply voltage decreases, gradually increases and then gradually decreases as the actual motor speed approaches the target motor speed over time.

[0014] Variation suppression control is performed by applying the voltage generated by the generator to the motor.

[0015] As described above, according to the motor control device of this disclosure, the generation unit generates a smoothly varying motor applied voltage using a predetermined function. Therefore, sudden changes in motor speed can be suppressed. The motor applied voltage generated by the generation unit is generated in such a way that the approach speed, which is lower than the actual motor speed due to the decrease in power supply voltage, gradually increases over time to approach the target motor speed. In other words, the initial approach speed after the power supply voltage has just started to rise is slow; therefore, even when the power supply voltage fluctuates repeatedly, regardless of the fluctuation, the variation in motor speed can be minimized. Furthermore, when the power supply voltage returns to its normal value and stabilizes, the motor applied voltage is generated in such a way that the approach speed gradually increases over time; therefore, the actual motor speed can quickly approach the target motor speed. Further, the motor applied voltage is then generated in such a way that the approach speed gradually decreases; therefore, the actual motor speed can slowly approximate the target motor speed.

[0016] Furthermore, the reference numbers in parentheses in the claims are merely examples of correspondences with specific structures in the embodiments described below, intended to facilitate understanding of this disclosure, and are not intended to limit the scope of this disclosure in any way.

[0017] Furthermore, the technical features described in each of the claims, other than those mentioned above, will become clear from the following description of the embodiments and the accompanying drawings. Attached Figure Description

[0018] Figure 1 This is a structural diagram showing the structure of the motor control device according to the first embodiment.

[0019] Figure 2It is used for explanation Figure 1 The waveform diagram of the motor control device's operation.

[0020] Figure 3 It is used to describe the upper limit of the voltage V applied to the motor. Mlimit Explanatory diagram.

[0021] Figure 4 This indicates a decrease in the power supply voltage V. DC When restoring to the original voltage value, the motor applies a maximum voltage V under repeated decreases and increases. Mlimit The waveform diagram shows the changes in the waveform.

[0022] Figure 5 This indicates that the motor control device of the first embodiment is used to suppress the speed of the three-phase motor from following the power supply voltage V. DC The flowchart shows the process of controlling the changes in response to changes in the data.

[0023] Figure 6 This is a structural diagram showing the structure of the motor control device according to the second embodiment.

[0024] Figure 7 It is used for explanation Figure 6 The waveform diagram of the motor control device's operation.

[0025] Figure 8 This indicates that the motor control device of the second embodiment is used to suppress the speed of the three-phase motor from following the power supply voltage V. DC The flowchart shows the process of controlling the changes in response to changes in the data. Detailed Implementation

[0026] <First Implementation Method>

[0027] Hereinafter, the motor control device of the first embodiment will be described with reference to the accompanying drawings. The motor control device of this embodiment, which will be described in detail later, can suppress the rotational speed of the three-phase motor from fluctuating with the power supply voltage when the power supply voltage supplied from the power source temporarily decreases, then rises and returns to normal. Therefore, the three-phase motor controlled by the motor control device of this embodiment can be well used, for example, as a fan motor that rotates the blower fan of a vehicle's air conditioning system. This is because, even if the power supply voltage supplied from the vehicle's power source fluctuates, as long as the fluctuation in the fan motor's rotational speed can be suppressed, for example, the generation of noise associated with changes in the airflow volume of the air conditioning system blowing into the passenger compartment can be suppressed. However, the application of the three-phase motor controlled by the motor control device of this embodiment is not limited to a fan motor. That is, the motor control device related to this embodiment can also control various three-phase motors mounted in vehicles. Furthermore, three-phase motors used in applications other than vehicles can also be controlled. Additionally, the motor controlled can be a motor other than a three-phase motor.

[0028] Figure 1 This illustrates the structure of the motor control device 10 according to the first embodiment. For example... Figure 1 As shown, the motor control device 10 includes a deviation calculation unit 12, a PI calculation unit 14, and a motor applied voltage upper limit (V) setting unit. Mlimit The motor control device 10 includes an arithmetic unit 16, a duty arithmetic unit 18 (which serves as a calculation unit), a PWM drive signal generation unit 20 (which serves as a drive unit), an inverter 22, and a current detection unit 24. These components, such as the PI arithmetic unit 14 and V... Mlimit The arithmetic unit 16 and the Duty arithmetic unit 18 can be formed by a microstructure having a general structure including a CPU, ROM, RAM, etc.

[0029] Deviation calculation unit 12 calculates the target motor speed ω given by the upper-level control device not shown in the figure. ＊ The deviation from the actual motor speed ω is calculated and fed to the PI calculation unit 14. The PI calculation unit 14 calculates the deviation from the target motor speed ω using proportional-integral control (PI control). ＊ The control quantity corresponding to the deviation from the actual motor speed ω is used as the motor applied voltage. This applied voltage is applied to the coils of each phase of the three-phase motor via PWM control, thereby making the actual motor speed ω approximate the target motor speed ω. ＊ Furthermore, the calculation is used to determine the target motor speed ω. ＊ The control rule for the control quantity (voltage applied to the motor) corresponding to the deviation from the actual motor speed ω is not limited to PI control; other control rules (such as PID control, PD control, etc.) can also be used.

[0030] V Mlimit The arithmetic unit 16 applies voltage to the motor calculated by the PI arithmetic unit 14, and calculates the upper limit voltage V applied to the motor, which is set to the upper limit voltage. Mlimit Regarding V Mlimit As for the arithmetic unit 16, as long as it does not generate the power supply voltage V DC The change (from a temporary decrease to the original power supply voltage V) DC (the recovery), just like Figure 2 The operation shown is related to the power supply voltage V. DC Equal voltage as the upper limit of the voltage applied to the motor V Mlimit Therefore, as Figure 1 As shown, V Mlimit The arithmetic unit 16 is configured to take in the power supply voltage V. DC And its voltage value can be detected. Or, V Mlimit The arithmetic unit 16 can also be configured to operate without generating a power supply voltage V. DC In the event of changes, no upper limit V is set for the voltage applied to the motor. Mlimit .

[0031] However, for example, when electric power steering is used under high load, or when electrical and electronic equipment with high power consumption is operating, the voltage V supplied from the vehicle battery may sometimes be insufficient. DC A temporary decrease. This power supply voltage V was generated. DC In the event of changes, such as Figure 2 As shown, V Mlimit The upper limit of voltage V applied to the operational motor of the arithmetic unit 16 Mlimit The motor applies a voltage limit V. Mlimit From the reduced power supply voltage V DC The voltage value at point t3, when it begins to rise, moves towards the source voltage V. DC The recovered voltage value changes as follows: the initial rate of increase is slow, but as time goes by, the rate of increase gradually increases, and then the rate of increase gradually decreases, at time point t4, it approximates the recovered voltage value.

[0032] This variation applies a voltage limit V to the motor. Mlimit For example, calculations can be performed using the transfer function of a first-order lag system where the cutoff frequency is a quadratic time variable that increases more significantly over time than a proportional relationship. For example, the upper limit voltage V applied to the motor... Mlimit It can be expressed using the first-order hysteresis transfer function through the following mathematical formula 1.

[0033] <Mathematical Formula 1>

[0034] V Mlimit (n)=VMlimit (n-1)+2πFT(V DC -V Mlimit (n-1))

[0035] In mathematical formula 1, F represents the cutoff frequency, and T represents the sampling period. Additionally, V... Mlimit (n-1) represents the previous value of the upper limit of the voltage applied to the motor, V Mlimit (n) represents the current value of the upper limit of the voltage applied to the motor.

[0036] Furthermore, in this embodiment, the cutoff frequency F of mathematical formula 1 is calculated as a quadratic time variable as shown in the following mathematical formula 2.

[0037] <Mathematical Formula 2>

[0038] F = F0 + F0C 2

[0039] In mathematical formula 2, F0 represents the initial value of the cutoff frequency, and C represents the cutoff frequency counter. When a decrease in the power supply voltage V is detected... DC When the frequency increases, the cutoff frequency counter C starts counting based on this detection. By squaring the count value of the cutoff frequency counter C and multiplying it by the initial cutoff frequency value F0, the value of the cutoff frequency F calculated by mathematical formula 2 is obtained as follows: Figure 3 As shown, it increases dramatically over time.

[0040] Thus, by using a first-order hysteresis transfer function with the cutoff frequency F as a quadratic time variable, the upper voltage limit V is applied to the motor. Mlimit The motor applies a maximum voltage V. Mlimit The change caused by the first-order hysteresis transfer function and the change in cutoff frequency are combined to achieve the following: Figure 3 As shown, it changes smoothly according to an S-shaped curve. That is, the upper limit of the voltage V applied to the motor... Mlimit The change is smooth in the following way: the initial rate of ascent is slow, but as time passes, the rate of ascent gradually increases, and then the rate of ascent gradually decreases. This is achieved by making the initial rate of ascent slow, for example, as... Figure 4 As shown, even with a reduced power supply voltage V DC When restoring to the original voltage value, the voltage is repeatedly decreased and increased, with the motor applying the upper voltage limit V. Mlimit The fluctuations are also suppressed to a smaller extent. Therefore, by applying a voltage limit V to the coils of each phase of the three-phase motor, the voltage applied to the motor is reduced. Mlimit A comparable voltage, even at the power supply voltage V DC Even with repeated changes, the variation in motor speed ω can be kept relatively small.

[0041] Furthermore, the above description explains how to calculate the upper limit of the applied voltage V of the motor using a first-order hysteresis transfer function with the cutoff frequency F as a quadratic time variable. Mlimit Examples. However, the motor applies a voltage limit V. Mlimit Other functions can also be used for calculation. For example, to calculate the upper limit V of the voltage applied to the motor. Mlimit Alternatively, a first-order hysteresis transfer function with the cutoff frequency F as a cubic time variable can be used. Furthermore, an exponential function or a sigmoid function can be used to calculate the upper limit of the motor voltage V, which varies in an S-shape. Mlimit In all cases, the upper limit of the voltage V applied to the motor is calculated using the desired function. Mlimit V Mlimit The arithmetic unit 16 is capable of calculating the upper limit of the motor applied voltage V, which varies smoothly in an S-shape. Mlimit .

[0042] From the detected decrease in power supply voltage V DC From the point t3 when the voltage starts to rise to the upper limit V of the applied voltage to the motor being calculated. Mlimit Approximately the power supply voltage V DC (or the actual motor speed ω is approximately equal to the target motor speed ω) ＊ During the period from time t4, V Mlimit The arithmetic unit 16 applies the upper voltage limit V to the motor being calculated. Mlimit Assigned to the Duty arithmetic unit 18. For other periods, V Mlimit The arithmetic unit 16 supplies the voltage applied to the motor by the PI arithmetic unit 14 to the Duty arithmetic unit 18. Alternatively, V Mlimit The arithmetic unit 16 can also be: if the voltage applied to the motor calculated by the PI arithmetic unit 14 is greater than the upper limit V of the voltage applied to the motor. Mlimit If the voltage is large, then the Duty calculation unit 18 will be given a voltage limit V applied to the motor. Mlimit If the voltage applied to the motor calculated by the PI calculation unit 14 is the upper limit V of the motor applied voltage. Mlimit Next, the voltage applied to the motor calculated by the PI calculation unit 14 is applied to the Duty calculation unit 18.

[0043] Duty computation unit 18 is based on V Mlimit The motor applied voltage or the upper limit V of the motor applied voltage is supplied by the arithmetic unit 16. Mlimit and power supply voltage V DC The PWM duty cycle is calculated. For example, the Duty calculation unit 18 can calculate the duty cycle corresponding to the motor applied voltage or the upper limit V of the motor applied voltage. Mlimit The magnitude is related to the power supply voltage V DC The ratio of the magnitude of the PWM duty cycle to the value of the PWM duty cycle. Therefore, for example, in V... MlimitThe arithmetic unit 16 applies a voltage limit V to the motor to the Duty arithmetic unit 18. Mlimit In this case, the Duty calculation unit 18 calculates the voltage applied to the coils of each phase of the three-phase motor 30, and the upper limit V applied to the motor. Mlimit The PWM duty cycle is equivalent to the applied voltage. The PWM duty cycle calculated by the Duty calculation unit 18 is assigned to the PWM drive signal generation unit 20.

[0044] The PWM drive signal generation unit 20 generates a PWM drive signal with a pulse width corresponding to the PWM duty cycle calculated by the Duty calculation unit 18, and outputs it to the inverter 22. The inverter 22 converts the DC power from the vehicle battery (not shown), which serves as a DC power source, into AC power and supplies it to the three-phase motor 30. The inverter 22 has three-phase bridge arms connected in parallel between the positive and negative terminals of the vehicle battery. Each phase bridge arm has multiple switching elements (e.g., IGBTs, MOSFETs, etc.) connected in series. By performing PWM control on the switching elements of each phase bridge arm provided in the inverter 22 according to the PWM drive signal generated by the PWM drive signal generation unit 20, the DC power supplied from the vehicle battery is converted into AC power and supplied to the three-phase motor 30. At this time, the motor applied voltage calculated by the PI calculation unit 14 or the voltage V applied by the PWM drive signal generation unit 18 is applied to the coils of each phase of the three-phase motor 30. Mlimit The upper limit of the voltage V applied to the motor is calculated by the arithmetic unit 16. Mlimit A comparable voltage.

[0045] The current detection unit 24 detects the current based on the induced voltage generated in the coils of each phase of the three-phase motor 30 by switching the coils of each phase that are energized. Thus, by detecting the current based on the induced voltage generated in the coils of each phase, the actual rotational speed ω of the three-phase motor 30 can be calculated. The calculation of the actual rotational speed ω of the three-phase motor 30 can be performed in the current detection unit 24, or it can be calculated based on the detected current in a different structure than the current detection unit 24. Alternatively, a position sensor that detects the rotational position of the three-phase motor 30 can be used to detect the actual rotational speed ω of the three-phase motor 30.

[0046] Next, in the motor control device 10 of this embodiment, referring to... Figure 5 A flowchart is used to illustrate the power supply voltage V DC It temporarily decreases, then increases and returns to the normal supply voltage V. DC At that time, the speed of the three-phase motor 30 is suppressed to follow the power supply voltage V. DC This is an example of the processing content that is controlled by the change of the change.

[0047] In the initial step S100, according to the target motor speed ω＊ The motor speed is controlled by a PI controller. Therefore, the actual speed ω of the three-phase motor 30 is controlled to follow the target motor speed ω. ＊ Through this control, for example, such as Figure 2 As shown, even at time point t1, the power supply voltage V DC The speed initially decreases temporarily, and during the period until time point t2, the actual motor speed ω is maintained at the target motor speed ω. ＊ .

[0048] Here, in Figure 2 During the period from time point t1 to time point t2, regardless of the power supply voltage V DC Whether the speed is reduced or not, the actual motor speed ω will be maintained at the target motor speed ω. ＊ Therefore, the PWM duty cycle increases. However, at time t2, the PWM duty cycle reaches 100%, and cannot increase further. Therefore, after time t2, PI control cannot maintain the actual motor speed ω at the target motor speed ω. ＊ With power supply voltage V DC Consequently, the actual motor speed ω also has to be reduced.

[0049] exist Figure 2 At time t3, when the power supply voltage V decreases DC When the switch is made to increase, the PWM duty cycle decreases from 100% to a value below 100%. Figure 5 Step S110 of the flowchart is at power supply voltage V DC After the PWM duty cycle is temporarily reduced and becomes 100%, it is determined that the PWM duty cycle has decreased from 100% to a value below 100% (e.g., 98%). That is, in step S110, based on the change in the PWM duty cycle, it is determined that the power supply voltage V has decreased. DC It changes to an increase. In addition, the power supply voltage V... DC Whether to switch to an increase can also be determined from the power supply voltage V. DC The change is directly determined. If the determination result in step S110 is "yes", the process proceeds to step S120. On the other hand, if the determination result in step S110 is "no", the process returns to step S100.

[0050] In step S120, fluctuation suppression control is initiated, which prevents the speed of the three-phase motor 30 from immediately following the power supply voltage V. DC The speed of the three-phase motor 30 increases rapidly due to the rise in voltage, and as a result, the speed of the three-phase motor 30 is determined by the power supply voltage V. DC The phenomenon that changes with the change. Specifically, in step S120, the counting of the cutoff frequency counter C mentioned above begins.

[0051] In step S130, the upper limit V of the motor applied voltage calculated in the variation suppression control is determined. Mlimit Is the power supply voltage V restored to its original value? DC That concludes the above. If the determination result of step S130 is "yes," it is no longer necessary to continue performing variation suppression control; therefore, the process proceeds to step S170. On the other hand, if the determination result of step S130 is "no," the process proceeds to step S140 in order to continue performing variation suppression control. Furthermore, in step S130, it is also possible to additionally or alternatively determine that the actual motor speed ω changes to the target motor speed ω. ＊ above.

[0052] In step S140, the upper limit of the voltage V applied to the motor is calculated using the desired function. Mlimit The motor applies a voltage limit V. Mlimit From the reduced power supply voltage V DC The voltage value at point t3, when it begins to rise, moves towards the source voltage V. DC The recovered voltage value changes as follows: initially, the rate of increase is slow, but as time passes, the rate of increase gradually increases, and then the rate of increase gradually decreases, reaching approximately the recovered voltage value at time point t4. Furthermore, the motor voltage application calculation process in step S140 is repeatedly executed in step S130 until the upper limit V of the motor voltage is determined. Mlimit Power supply voltage V DC The above describes the repeated steps of step S140, which involves applying voltage to the motor. Each time this process is executed, the count value of the cutoff frequency counter C and the power supply voltage V are updated. DC And since the previous value of the upper limit of the motor applied voltage has changed, the different upper limits of the motor applied voltage V that vary along the S-shaped curve are calculated. Mlimit .

[0053] In step S150, the calculation is performed to apply the upper limit V of the applied voltage to the coils of each phase of the three-phase motor 30. Mlimit The PWM duty cycle is determined by the applied voltage. The calculated PWM duty cycle is output to the PWM drive signal generation unit 20 in step S160.

[0054] In step S170, the variation suppression control is terminated. At this timing, the counting operation of the cutoff frequency counter C stops. Then, in step S180, the count value of the cutoff frequency counter C is cleared. Figure 5 The process shown in the flowchart has ended.

[0055] As described above, the motor control device 10 according to this embodiment calculates the voltage V from the reduced power supply voltage using a predetermined function.DC The voltage value at point t3, when it begins to rise, moves towards the source voltage V. DC The motor, after recovery, smoothly changes its voltage value, applying the upper voltage limit V. Mlimit Then, the upper limit voltage V applied to each phase coil of the three-phase motor 30 is applied to the motor. Mlimit A suitable applied voltage is used. Therefore, it is possible to suppress sudden changes in the actual motor speed ω.

[0056] Motor applied voltage limit V Mlimit So that due to the power supply voltage V DC The actual motor speed ω decreases due to the reduction, and then approaches the target motor speed ω over time. ＊ It is generated by gradually increasing approach velocity. In other words, the power supply voltage V DC The initial approach speed after the voltage has just started to rise is slow; therefore, even at the power supply voltage V... DC In the case of repeated changes, regardless of the power supply voltage V DC Regardless of the changes, the actual variation in motor speed ω can be suppressed to a small extent.

[0057] Additionally, at the power supply voltage V DC Once the voltage returns to its normal value and stabilizes, the motor applies a maximum voltage V. Mlimit To make the actual motor speed ω close to the target motor speed ω ＊ The voltage applied to the motor is generated by gradually increasing the approach speed over time. Therefore, it is possible to rapidly bring the actual motor speed ω close to the target motor speed ω. ＊ Furthermore, the upper limit of the voltage V applied to the motor is then generated in a manner that gradually reduces the approach speed. Mlimit Therefore, it is possible to gradually approximate the actual motor speed ω with the target motor speed ω. ＊ .

[0058] <Second Implementation Method>

[0059] Next, the motor control device of the second embodiment of this disclosure will be described with reference to the accompanying drawings. In the motor control device 10 of the first embodiment described above, when the power supply voltage V is reduced... DC During the upward movement, the upper limit is determined by applying voltage to the motor, i.e., the upper limit V of the motor applied voltage. Mlimit This suppresses the variation in the actual motor speed ω.

[0060] In contrast, the motor control device 110 of the second embodiment operates at a reduced power supply voltage V. DC During the ascent, the target transition motor speed n is determined. trgt To suppress the variation of the actual motor speed ω, the transition target motor speed ntrgt From the power supply voltage V DC The actual motor speed ω at the point of transition to an upward motion, towards the target motor speed ω ＊ The ascent speed gradually increases over time, and then gradually decreases. Hereinafter, the motor control device of the second embodiment will be described focusing on its differences from the motor control device 10 of the first embodiment.

[0061] like Figure 6 As shown, the motor control device 110 of this embodiment has a transition target motor speed (n) as a transition target setting unit. trgt The arithmetic unit 116 is used to replace the V of the motor control device 10 in the first embodiment. Mlimit Arithmetic unit 16.

[0062] As long as no power supply voltage V is generated DC The change (from a temporary decrease to the original power supply voltage V) DC (recovery), n trgt Arithmetic unit 116 is like Figure 7 The single-dotted line in the middle will be related to the target motor speed ω. ＊ Equal rotational speeds are determined as the transition target motor speed n. trgt Or, in Figure 7 At time t2, even though the PWM duty cycle is 100%, the actual motor speed ω begins to decrease. trgt The calculation unit 116 can also set the transition target motor speed n in a manner that follows the decrease in the actual motor speed ω. trgt Moreover, n trgt The arithmetic unit 116 can also be configured to operate up to the power supply voltage V. DC Temporarily reduce and lower the power supply voltage V DC Until the transition to an upward direction, no transition target motor speed n is set. trgt .

[0063] However, at the power supply voltage V DC The voltage drops temporarily, then returns to the original supply voltage V. DC The restored power supply voltage V DC In the event of changes, such as Figure 7 As shown, n trgt The arithmetic unit 116 uses the desired function to calculate the transition target motor speed n. trgt The target motor speed n during the transition trgt From the reduced power supply voltage V DC The actual motor speed ω at the point t3 when the upward movement begins, moving towards the target motor speed ω. ＊The change occurs as follows: the initial ascent rate is slow, but gradually increases over time, then gradually decreases, reaching approximately the target motor speed ω at time t4. ＊ .

[0064] Furthermore, as a means of calculating the transition target motor speed n trgt The desired function used is the same as in the first embodiment, and can be a first-order lag transfer function with the cutoff frequency F as a quadratic time variable, a first-order lag transfer function with the cutoff frequency F as a cubic time variable, an exponential function, or a sigmoid function, etc.

[0065] PI arithmetic unit 114 at least from Figure 7 From time point t3 to time point t4, calculate the actual motor speed ω and the transition target motor speed n. trgt The control quantity corresponding to the deviation is used as the motor applied voltage. The Duty calculation unit 118 calculates the magnitude of the motor applied voltage and the power supply voltage V, which are calculated by the PI calculation unit 114. DC The ratio of the magnitude to the PWM duty cycle. Therefore, as... Figure 7 As shown, it is possible to control the voltage applied to the coils of each phase of the three-phase motor 130 during the period from time t3 to time t4, so that regardless of the power supply voltage V DC Whether the voltage returns to the original value or not, the actual motor speed ω varies with the transition target motor speed n. trgt It changes in an S-shape. As a result, using the motor control device 110 of this embodiment, the power supply voltage V... DC It temporarily decreases, and then produces the kind of power supply voltage V that restores to its original value. DC When the value is changed, it can also achieve the same effect as that described in the first embodiment.

[0066] Figure 8 This indicates that in the motor control device 110 of this embodiment, when the power supply voltage V... DC It temporarily decreases, then increases and returns to the normal supply voltage V. DC At that time, the speed of the three-phase motor 30 is suppressed to follow the power supply voltage V. DC A flowchart illustrating an example of the process for controlling changes in response to variations.

[0067] Steps S200 to S220 and steps S270 to S280 and Figure 5 The steps S100 to S120 and S170 to S180 of the flowchart are the same, so the explanation is omitted.

[0068] In step S230, the transition target motor speed n calculated in the variation suppression control is determined.trgt Is it consistent with the target motor speed ω assigned by the superior control device? ＊ Consistent. In this determination process, the actual motor speed ω varies with the transition target motor speed n. trgt Therefore, it is possible to determine whether the actual motor speed ω is similar to the target motor speed ω. ＊ Consistent. If the determination result of step S230 is "yes", there is no need to continue performing change suppression control, and therefore, proceed to step S270. On the other hand, if the determination result of step S230 is "no", change suppression control continues to be performed, and therefore, proceed to step S240.

[0069] In step S240, the target transition motor speed n is calculated using the desired function. trgt The target motor speed n during the transition trgt From the reduced power supply voltage V DC The actual motor speed ω at the point t3 when the upward movement begins, moving towards the target motor speed ω. ＊ The change occurs as follows: the initial ascent rate is slow, but gradually increases over time, then gradually decreases, reaching approximately the target motor speed ω at time t4. ＊ Furthermore, the transition target motor speed n is repeatedly calculated in step S240 until the determination result of step S230 becomes "yes". trgt This approach differs from the first embodiment where the motor is subjected to a voltage limit V. Mlimit The operations are the same.

[0070] In step S250, calculations are performed to apply a transition target motor speed n to the coils of each phase of the three-phase motor 130. trgt The PWM duty cycle of the applied motor voltage is calculated based on the deviation from the actual motor speed ω. Then, in step S260, the calculated PWM duty cycle is output to the PWM drive signal generation unit 120.

[0071] The preferred embodiments of this disclosure have been described above, but this disclosure is not limited to the above embodiments in any way, and can be implemented in various modifications without departing from the spirit of this disclosure.

[0072] For example, the motor control devices 10 and 110 and their methods described in this specification can be implemented by a dedicated computer provided by means of a processor and memory programmed to perform one or more functions embodied in a computer program. Alternatively, the motor control devices 10 and 110 and their methods described in this specification can also be implemented by a dedicated computer provided by means of a processor constructed using one or more dedicated hardware logic circuits. Alternatively, the motor control devices 10 and 110 and their methods described in this specification can also be implemented by one or more dedicated computers configured by means of a combination of a processor and memory programmed to perform one or more functions of a computer program and a processor constructed of one or more hardware logic circuits. Furthermore, the computer program can also be stored as instructions to be executed by the computer in a computer-readable non-transitional tangible recording medium.

Claims

1. A motor control device that performs variation suppression control to prevent the motor speed from following the variation of the power supply voltage when the power supply voltage supplied from the power source for driving the motor temporarily decreases, then rises and returns to the normal power supply voltage, characterized in that, have: The detection department detects a decrease in power supply voltage, which then increases; and The generation unit, based on the detection unit's finding that the power supply voltage is rising, generates an applied voltage for the motor using a predetermined function. This voltage is generated in a manner that, as the actual motor speed decreases due to the decrease in power supply voltage, the speed of increase gradually approaches the target motor speed over time. Initially, the speed of increase is slow, but as time passes, the speed of increase gradually increases, and then the speed of increase gradually decreases. The variation suppression control is performed by applying the voltage generated by the generating unit to the motor. The specified function is the transfer function of a first-order lag system that contains a cutoff frequency that increases more significantly over time than a proportional relationship.

2. The motor control device according to claim 1, characterized in that, The motor is controlled by PWM via an inverter. The generating unit includes: The upper limit setting unit uses the specified function to set the upper limit of the motor applied voltage. The upper limit of the motor applied voltage changes from the power supply voltage at the point when it turns to rise to the normal power supply voltage after recovery, with an initial slow rise rate, but as time goes by, the rise rate gradually increases, and then the rise rate gradually decreases. The calculation unit calculates the PWM duty cycle for applying an applied voltage to the motor that is equivalent to the upper limit of the applied voltage set by the upper limit setting unit, regardless of whether the power supply voltage rises or not. as well as The drive unit drives the inverter according to the PWM duty cycle calculated by the calculation unit.

3. The motor control device according to claim 1, characterized in that, The motor is controlled by PWM via an inverter. The generating unit includes: The transition target setting unit uses the specified function to set the transition target motor speed. The transition target motor speed changes from the actual motor speed at the point when the power supply voltage changes to rise towards the target motor speed with an initial slow increase rate, but as time goes by, the increase rate gradually increases and then the increase rate gradually decreases. The calculation unit calculates the PWM duty cycle, regardless of whether the power supply voltage rises or falls, to ensure that the actual motor speed follows the transition target motor speed set by the transition target setting unit; and The drive unit drives the inverter according to the PWM duty cycle calculated by the calculation unit.

4. The motor control device according to claim 2 or 3, characterized in that, Even though the PWM duty cycle is 100%, if the actual motor speed decreases compared to the target motor speed, and the PWM duty cycle changes from 100% to below 100%, the detection unit detects a decrease in the power supply voltage, and the decreased power supply voltage then increases.

5. The motor control device according to claim 2, characterized in that, When the upper limit of the motor applied voltage set by the upper limit setting unit becomes higher than or equal to the restored power supply voltage, the fluctuation suppression control ends.

6. The motor control device according to claim 3, characterized in that, When the transition target motor speed set by the transition target setting unit matches the target motor speed, the variation suppression control ends.

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