JP7757690B2 - Measurement value acquisition method and measurement value acquisition device - Google Patents

Description

The present invention relates to a measurement value acquisition method and a measurement value acquisition device.

A multiplexer is known that switches between the measured values detected by multiple sensors one by one and outputs them to a control device that controls the operation of various actuators, measuring the measured values of a specific physical quantity. By using a multiplexer, it is possible to reduce the processing load on the control device and the number of input terminals compared to inputting all of the multiple measured values obtained into the control device.

Patent Document 1 discloses one aspect of a control system that uses a multiplexer. In particular, the multiplexer in Patent Document 1 outputs measured values of physical quantities at various locations in an on-board battery pack (for example, measured values of battery temperature obtained at each location) to an on-board electronic control unit (ECU) while periodically switching between them in response to count values for pulse signals of a predetermined frequency.

Japanese Patent Application Laid-Open No. 2004-173374

However, the multiplexer described above is configured to output all measurement values obtained from the sensors to the control device by switching between them one by one per unit period. Therefore, if the number of measurement values to be output to the control device increases, for example, due to an increase in the number of installed sensors, the frequency with which a specific measurement value is output to the control device per unit time decreases.

For this reason, for example, in situations where it is important to understand changes in a specific measurement value in order to properly control the operation of an actuator, which is the object of control, there may be a time lag between when that measurement value is obtained by sensors and when it is selected by the multiplexer as the final measurement value and actually output to the control device. As a result, there is a problem in that the accuracy of the final measurement value decreases from the perspective of the control device using this final measurement value to properly control the actuator.

In view of the above-mentioned problems, an object of the present invention is to provide a measurement value acquisition method and measurement value acquisition device that can suppress a decrease in the accuracy of a final measurement value when determining one of multiple measurement values as the final measurement value.

According to one aspect of the present invention, there is provided a measurement value acquisition method for determining one of physical quantity measurements obtained at multiple measurement positions of an actuator controlled by a predetermined control device as a final measurement value to be used for controlling the actuator. This measurement value acquisition method includes a setting step of determining an operating state parameter indicating an operating state of the actuator correlated with each physical quantity measurement; and a determination step of determining the final measurement value by executing either first selection control or second selection control with reference to the operating state parameter. The actuator also includes a power adjustment unit that adjusts the phase current of an AC motor, and each of the physical quantity measurements is a temperature detection value for each phase of the power adjustment unit. The operating state parameter further includes a reference current indicating the magnitude of the current in each phase and a rotation speed of the AC motor. The determination step determines whether to execute the first selection control or the second selection control based on the rotation speed of the AC motor. In the first selection control, a phase with the maximum current is identified based on the reference current, and the temperature detection value detected in that phase is determined as the final measurement value. In the second selection control, the temperature detection value of the phase determined as the final measurement value at a previous control timing is fixed as the final measurement value. If the first selection control was executed at the previous control timing, the execution of the first selection control is determined when the rotation speed of the AC motor is equal to or less than a predetermined first threshold determined according to the length of the unit control time, and if not, the execution of the second selection control is determined. Also, if the second selection control was executed at the previous control timing, the execution of the first selection control is determined when the rotation speed of the AC motor is equal to or less than a second threshold smaller than the first threshold, and if not, the execution of the second selection control is determined.

This makes it possible to suppress a decrease in the accuracy of one of the multiple measurement values when outputting that final measurement value to the control device as the final measurement value.

FIG. 1 is a diagram illustrating the configuration of a measurement value acquisition device (motor controller) common to each embodiment and a motor control system including the same. FIG. 2 is a flowchart illustrating a process executed by the motor controller common to all the embodiments. FIG. 3 is a flowchart illustrating the measurement value determination process according to the first embodiment. FIG. 4 is a diagram illustrating the effects of the first embodiment. FIG. 5 is a diagram illustrating the effects of the second embodiment. FIG. 6 is a diagram illustrating an example in which the phase current is not uniquely determined with respect to the electrical angle of the motor in the third embodiment. FIG. 7 is a diagram illustrating the effects of the fourth embodiment. FIG. 8 is a diagram illustrating the effects of the fifth embodiment. FIG. 9 is a flowchart illustrating the selection control determination process according to the sixth embodiment. FIG. 10 is a flowchart illustrating the measurement value determination process of the sixth embodiment. FIG. 11 is a diagram illustrating the effects of the sixth embodiment. FIG. 12 is a flowchart illustrating the second selection control of the seventh embodiment. FIG. 13 is a diagram illustrating the effects of the seventh embodiment.

Each embodiment of the present invention will be described below with reference to the drawings.

[Common system configuration]
FIG. 1 is a diagram illustrating the configuration of a motor control system 1 equipped with a measurement value acquisition device common to all embodiments.

The motor control system 1 controls the operating point (particularly, output torque, etc.) of the motor 30, which serves as an AC motor, using input information from a host controller 40, a specified external device (not shown) connected via an in-vehicle network such as a CAN network, or detection values obtained from various sensors. In particular, the motor control system 1 of this embodiment is intended to be a system for controlling the operating point (particularly, output torque, etc.) of the motor 30, which is configured as a three-phase AC motor used as a driving source for a vehicle.

More specifically, the motor control system 1 has a motor controller 10 that functions as a measurement value acquisition device, and a power adjustment unit 20 that is an actuator that operates in response to command signals input from the motor controller 10.

Furthermore, the motor controller 10 mainly includes a microcontroller 11 and a multiplexer 13.

The microcomputer 11 functions as a control device that controls the power adjustment unit 20. In particular, the microcomputer 11 generates a PWM signal for controlling the operation of the power adjustment unit 20 in response to various input information. Furthermore, in this embodiment, the microcomputer 11 generates a command signal for the multiplexer 13 based on the measurement value determination process described below, and outputs this to the multiplexer 13.

The microcomputer 11 is composed of a computer equipped with a central processing unit (CPU), read-only memory (ROM), random access memory (RAM), and input/output interface (I/O interface). The controller may be configured as a single device, or may be divided into multiple blocks and configured so that each process of this embodiment is distributed across the multiple blocks. In particular, the microcomputer 11 executes the processes shown in each flowchart described below in accordance with programs stored in the memory area of the microcomputer 11.

The multiplexer 13 performs a predetermined process on the temperature detection value _Tx detected by the temperature sensor 12 to determine a final measurement value _Tme , which is output to the microcomputer 11. In particular, the temperature sensor 12 in this embodiment is composed of three sensors: a U-phase temperature sensor 12U, a V-phase temperature sensor 12V, and a W-phase temperature sensor 12W. In accordance with a command signal received from the microcomputer 11, the multiplexer 13 outputs one of the U-phase temperature detection value _Tu , the V-phase temperature detection value _Tv , and the W-phase temperature detection value _Tw , which are the detection values (measured values) detected by these three sensors, to the microcomputer 11 as the final measurement value _Tme .

The power adjustment unit 20 also includes an inverter 21, a DC power supply 22, and a smoothing capacitor 23.

The inverter 21 operates the switching elements 24 to realize a switching pattern based on the PWM signal input from the microcomputer 11. In particular, the switching elements 24 are composed of a U-phase switching element 24U, a V-phase switching element 24V, and a W-phase switching element 24W, which are responsible for supplying power to the UVW phases, respectively.

The DC power supply 22 is composed of an on-board battery or the like. Furthermore, a smoothing capacitor 23 is connected in parallel between the inverter 21 and the DC power supply 22, and smooths the power supplied to the inverter 21.

Therefore, by switching the switching elements 24U, 24V, and 24W in response to the PWM signal, the inverter 21 functions as an actuator that converts the DC power supplied from the DC power supply 22 into AC power and supplies it to the motor 30 (powering operation), or converts the regenerative energy of the motor 30 into DC power and supplies it to the DC power supply 22 (regenerative operation).

Furthermore, the above-mentioned U-phase temperature sensor 12U, V-phase temperature sensor 12V, and W-phase temperature sensor 12W are positioned to detect the temperatures of the U-phase switching element 24U, V-phase switching element 24V, and W-phase switching element 24W, respectively. In other words, the power adjustment unit 20 is provided with temperature sensors 12U, 12V, and 12W corresponding to the three switching elements 24U, 24V, and 24W of the motor 30, which operates in the three phases UVW.

Next, we will explain the PWM signal generation control, including the measurement value determination process performed by the microcontroller 11.

Figure 2 is a flowchart explaining the processing executed by the motor controller 10. Note that the motor controller 10 repeatedly executes each process shown in Figure 2 at predetermined calculation intervals.

In step S1, the microcomputer 11 acquires various input information. Here, the input information includes a torque command value received from the upper controller 40 or a predetermined external device, the DC voltage of the DC power supply 22 received from a voltage sensor (not shown), detected values of the phase currents ( _iu , _iv , _iw ) of the motor 30 received from the current sensor 32, the detected value of the magnetic position θ received from the magnetic pole position sensor 31, and the final measurement value _Tme output by the multiplexer 13. In addition, the microcomputer 11 determines the electrical angle _θe and rotation speed of the motor 30 (hereinafter, "motor rotation speed _ωr ") from the detected value of the magnetic position θ as input information for generating a PWM signal.

In step S2, the microcomputer 11 calculates dq-axis current command values (i*d, i*q), which are command values for the currents of the motor 30 (hereinafter also referred to as ^" dq-axis currents ( _id , _iq )") expressed in a rotating coordinate system (dq-axis coordinate system), based on the various _input information obtained in step _S1 . Specifically, the microcomputer 11 determines the dq-axis current command values (i ^* _d , i ^* _q ) from the various input information by referring to a map that defines appropriate dq-axis currents ( ^id , _iq ) for achieving each operating point of the motor 30. Note that _this map is prepared in advance in any storage area accessible by the microcomputer 11.

In step S3, the microcomputer 11 executes current vector control. Specifically, the microcomputer 11 calculates a voltage command value v* so that the d-axis and q-axis currents (i _d , i _q ) determined from various input information such as the phase currents (i _u , _iv , i _w ) and magnetic position ^θ acquired in step S1 coincide with the d-axis and q-axis current command values (i ^* _d , i ^* _q ) calculated in step S2.

In step S4, based on the DC voltage acquired in step S1 and the voltage command value v ^* calculated in step S3, the microcomputer 11 determines a duty command value that defines an appropriate switching pattern for the switching element 24. Then, the microcomputer 11 generates a switching signal according to the duty command value and outputs it to the switching elements 24U, 24V, and 24W.

Furthermore, in step S5, the microcomputer 11 executes a measurement value determination process to generate a command signal for the multiplexer 13. The microcomputer 11 then outputs the generated command signal to the multiplexer 13.

In the following embodiments, each aspect of this measurement value determination process will be described in detail.

[First embodiment]
3 is a flowchart illustrating the measurement value determination process in this embodiment. The microcomputer 11 repeatedly executes each process shown in FIG. 3 at predetermined unit control times Δt _smp (sampling times). In the following description, when distinguishing between the control timings t _c , subscripts such as "-1,""0," and "+1" are added to the symbols of the parameters as appropriate. Specifically, the "current control timing t _c0 ,""previous control timing t _c-1 ," and "next control timing t _c+1 " are used.

In step S510, the microcomputer 11 acquires measurement information at the previous control timing t c _-1 . In particular, the microcomputer 11 acquires information regarding whether the first selection control or a predetermined basic selection control (second selection control) was executed at the previous control timing t _c-1 , and information regarding the detected temperature value T _x-1 (x is u, v, or w) determined as the final measurement value T _me-1 .

In step S520, the microcomputer 11 executes a selection control determination process based on the various input information (particularly the motor rotation speed _ωr ) acquired in step S1 and the measurement information at the previous control timing tc _-1 . The selection control determination process is a process for determining whether the first selection control or the second selection control should be executed when determining the final measurement value _Tme at the current control timing _tc. In particular, the microcomputer 11 references the motor rotation speed _ωr at which execution of the first selection control is permitted and the previous measurement information, and appropriately sets and clears an authorization flag that permits execution of the first selection control.

In step S530, the microcomputer 11 executes a determination current setting process. Specifically, the microcomputer 11 sets determination currents ( _Iju , _Ijv , _Ijw ) to be used in the first selection control. The determination currents ( _Iju , _Ijv , _Ijw ) are parameters primarily used to select the temperature detection value _Tx (x is u, v, or w) to be used as the final measurement value _Tme . More specifically, parameters indicating the magnitude of each component of the phase currents ( _iu , _iv , _iw ) are used as the determination currents ( _Iju , _Ijv , _Ijw ). In particular, in this embodiment, detected or estimated phase currents ( _iu , _iv , _iw ) are used as the determination currents ( _Iju , _Ijv , _Ijw ).

In step S540, the microcomputer 11 executes a measurement value determination process depending on whether the permission flag is set or not. The measurement value determination process is a process of executing either the first selection control or the second selection control to determine the temperature detection value _Tx to be the final measurement value _Tme at the current control timing _tc .

In the first selection control, the phase in which each component of the determination current ( _Iju , _Ijv , _Ijw ) has the maximum value is identified. Then, the microcomputer 11 determines the temperature detection value _Tx obtained by the temperature sensor 12x corresponding to the identified phase as the final measurement value Tme. In other words, the measured temperature of the switching element 24U, 24V, 24W in the power adjustment unit 20 through which the maximum current flows is determined _as the final measurement value _Tme .

On the other hand, in the second selection control, the final measurement value _Tme is determined using a selection criterion different from that of the first selection control. For example, in the second selection control, the final measurement value _Tme is determined in accordance with the standard function of the multiplexer 13. Specifically, one of the temperature detection values _Tw , _Tv , and _Tu is selected in sequence at a predetermined switching period to become the final measurement value _Tme . For ease of explanation, the algorithm for determining the final measurement value _Tme based on the standard function of the multiplexer 13 will also be simply referred to as "standard switching control" below.

Then, in step S550, the microcomputer 11 generates a command signal for outputting the detected temperature value _Tx to be the final measured value _Tme determined in step S540, and outputs this to the multiplexer 13.

The following describes the effects achieved by implementing the control of this embodiment.

4A and 4B are diagrams illustrating the effects of this embodiment. In particular, Fig. 4A shows the change over time in the absolute values of the components of the phase currents ( _iu , _iv , _iw ) in the low rotation range of the motor 30. Fig. 4B shows an example of the change over time in the detected U-phase temperature value _Tu , the detected V-phase temperature value _Tv , and the detected W-phase temperature value _Tw .

Furthermore, the open plots in FIG. 4B indicate the final measured value _Tme determined based on the standard switching control, and the closed plots indicate the final measured value _Tme determined based on the first selection control.

First, in standard switching control, the U-phase temperature detected value _Tu , the V-phase temperature detected value _Tv , and the W-phase temperature detected value _Tw are switched in order for each unit control time _Δtsmp to reach the final measured value _Tme .

However, depending on the operating state of the motor 30, it is possible that the magnitude of the current flowing through each of the switching elements 24U, 24V, and 24W may vary, resulting in an imbalance in the temperature distribution of each phase. In particular, in the low rotation range, certain phase components of the phase currents ( _iu , _iv , _iw ) (U-phase current _iu and W-phase current _iw in the figure) may become larger than other phase components (V-phase current _iv in the figure), causing a high current to flow through the switching elements 24U and 24W of the corresponding phase, resulting in a rise in their temperatures.

However, in the case of standard switching control, the temperature detection value _Tx that becomes the final measurement value _Tme switches every unit control time _Δtsmp, regardless of current concentration in a specific phase. As a result, the frequency (measurement interval ₎ at which the temperature detection value _Tu or _Tw associated with the switching element 24U or 24W with a high temperature, which is the desired temperature, is selected as the final measurement value Tme decreases. More specifically, in the example shown in FIG. 4B, the measurement interval for the high-temperature U-phase (the time interval at which the U-phase temperature detection value _Tu becomes the final measurement value _Tme ) is approximately three times the unit control time _Δtsmp .

In contrast, with the first selection control, at each control timing _tc , the U-phase temperature detection value _Tu associated with the U-phase, which has the largest current, is selected as the final measurement value _Tme . That is, the temperature of the U-phase switching element 24U with the highest temperature is measured preferentially. This allows the microcomputer 11 to more effectively execute subsequent control (especially control of the power adjustment unit 20 related to protection at high temperatures) using the temperature measurement result (i.e., the final measurement value _Tme ).

The configuration of the above embodiment and the effects of this configuration will be explained below.

In this embodiment, a measurement value acquisition method is provided in which one of temperature detection values Tw, Tv, and _{Tu ,} which are physical quantity measurement values obtained at multiple measurement positions (U-phase temperature sensor 12U, V-phase temperature sensor 12V, and W-phase temperature sensor 12W) in an actuator (power adjustment unit ₂₀ or motor 30) controlled by a predetermined control device (microcomputer 11), is determined as a final measurement value _Tme to be used for controlling the actuator.

This measurement value acquisition method includes a setting step (step _S1 , step S530) of determining operating state parameters (motor rotation speed _ωr and judgment current (I _ju , I _jv , I _jw )) that indicate the operating state of the actuator (particularly the motor ₃₀ ) correlated with each of the temperature detection values T _w , T v , and T u , and a determination step (step S540, step S550) of determining the final measurement value T _me by performing selection control (first selection control) that selects one temperature detection value T _x to be used as the final measurement value T _me by referring to the operating state parameters.

This makes it possible to determine an appropriate value to be focused on as the final measurement value _Tme from among the physical quantity measurement values obtained at a plurality of measurement positions according to the operating state of the actuator, thereby making it possible to obtain a final measurement value _Tme with an appropriate level of accuracy from the viewpoint of using it for various subsequent controls of the actuator.

In particular, the actuator assumed in this embodiment includes a power adjustment unit 20 that adjusts the phase currents ( _iu , _iv , _iw ) of the motor 30, which is an AC motor. Furthermore, the respective measured physical quantities are the temperature detection values of each phase (U-phase temperature detection value _Tu , V-phase temperature detection value _Tv , and W-phase temperature detection value _Tw ) of the power adjustment unit 20 (in particular, switching elements 24U, 24V, 24W).

In the setting step, the determination currents (I _ju , I _jv , I _jw ) indicating the magnitude of the current in each phase are determined as operating state parameters. In the first selection control, the phase with the maximum current is identified based on the determination currents (I _ju , I _jv , I _jw ), and the temperature detection value T _x detected in that phase is determined as the final measurement value T _me .

This allows the phase that is likely to have a relatively high temperature to be identified through the determination current that correlates with the temperature of the switching elements 24U, 24V, and 24W of each phase, and then the detected temperature value _Tx of that phase can be set as the final measured value _Tme . In other words, a suitable control logic is realized for preferentially measuring the temperature of the phase that will have a high temperature with high frequency.

Furthermore, in this embodiment, a motor controller 10 is provided as a measurement value acquisition device suitable for implementing the above measurement value acquisition method. More specifically, the motor controller 10 determines one of temperature detection values Tw, Tv, and Tu _, which are physical quantity measurement values obtained at multiple measurement positions (U-phase temperature sensor 12U, V-phase temperature sensor 12V, and W-phase temperature sensor 12W) in an actuator (power adjustment unit ₂₀ or _motor 30) controlled by a predetermined control device (microcomputer 11), as a final measurement value _Tme to be used for controlling the actuator.

In particular, the motor controller 10 has a setting unit (steps S1, S530) that determines operating state parameters that indicate the operating state of the actuators correlated with the respective temperature detection values _Tw , _Tv , and _Tu , and a determination unit (steps S540, S550) that determines the final measured value _Tme by performing selection control to select one temperature detection value _Tx to be the final measured value _Tme by referring to the operating state parameters.

Second Embodiment
The second embodiment will be described below, with the same elements as those in the first embodiment being given the same reference numerals and their description being omitted.

In this embodiment, an embodiment will be described in which the judgment current setting process (step S530) uses the judgment currents (I _ju , I _jv , I _jw ) as estimated values of the phase currents (i _u , _iv , i _w ) calculated based on the electrical angle _θe (hereinafter also referred to as "estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} )").

More specifically, in step S530, the microcontroller 11 refers to a map prepared in advance in an accessible storage area, calculates estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ) from the electrical angle _θe acquired in step S1 of Figure 2, and sets these as judgment currents (I _ju , I _jv , I _jw ).

The following describes the effects of the control provided by this embodiment.

5A to 5C are diagrams illustrating the effects of this embodiment. In particular, FIGS. 5A to 5C each show the changes over time in the temperature of each phase and the absolute values of each component of the phase current ( _iu , _iv , _iw ) for different electrical angles _θe . As shown in the diagrams, the absolute values of each component of the phase current ( _iu , _iv , _iw ) behave differently when the electrical angle _θe changes. In other words, the estimated phase currents ( _{iu_es} , _{iv_es} , _{iw_es} ) determined from the electrical angle θe _function favorably as the determination currents ( _Iju , _Ijv , _Ijw ) for determining the final measurement value _Tme .

Therefore, with the measurement value acquisition method _{of this} embodiment, the control algorithm _for determining the final measurement value _Tme described in the first embodiment can be suitably applied even to a motor control system that does not have a current sensor 32 that directly detects the phase currents (iu, iv, _iw ). In particular, in a motor control system that determines the phase currents ( _iu , iv, _iw ) from the electrical angle _θe in a feedforward manner to achieve a desired motor torque, there is a stronger correlation between changes in the electrical angle _θe and the behavior of the phase currents ( _iu , _iv , _iw ). Therefore, it is particularly preferable to apply the control configuration of this embodiment to such a motor control system.

[Third embodiment]
The third embodiment will be described below, with the same elements as those in the first or second embodiment being given the same reference numerals, and the description thereof will be omitted.

In this embodiment, assuming the control mode of the second embodiment, an example will be described in which the electrical angle _θe is used to calculate the current command value of the motor 30. More specifically, an example will be described in which the estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ) are calculated by performing a two-phase/three-phase conversion on the d-axis and q-axis current command values (i ^* _d , i ^* _q ) of the motor 30 using _the electrical angle θe.

In general, depending on the operating point of the motor 30, the phase currents ( _iu , _iv , _iw ) may not be uniquely determined for the electrical angle _θe . For example, in a scene where the operating point of the motor 30 is controlled by current vector control (step S3), the main manipulated variable in this control is the phase of the current (current phase angle φ). For this reason, under current vector control, there may be operating points of the motor 30 that have different current phase angles φ for the same electrical angle _θe , and the phase currents ( _iu , _iv , _iw ) may not be uniquely determined.

An example of such a scene is shown in Figure 6. In particular, Figures 6(a) and 6(b) show the changes over time in the absolute values of the temperatures of each phase and each component of the phase current ( _iu , _iv , _iw ) in scenes where different current phase angles φ are taken for the same electrical angle _θe .

As shown in the figure, in scenes where different current phase angles φ are taken for the same electrical angle _θe , the relative magnitude relationships of the absolute values of the components of the phase currents ( _iu , _iv , _iw ) also differ.

Therefore, if the judgment currents (I _ju , I _jv , I _jw ) are determined from the estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ) based on the electrical angle _θe and then used to determine the temperature detection value T _x that should be the final measurement value T _me , the accuracy of the final measurement value T _me may decrease.

In contrast to this, in this embodiment, the electrical angle _θe is used to perform two-phase/three-phase conversion on the dq-axis current command values (i ^* _d , i ^* _q ) of the motor 30 to obtain estimated phase currents ( _{iu_es} , _{iv_es} , _{iw_es} ), and the absolute values of these estimated phase currents are used as the determination currents ( _Iju , _Ijv , _{Ijw). Therefore, it is possible to obtain determination currents (Iju, Ijv, Ijw ) that are} more suited to the actual operating points of the motor 30, and it is possible to more appropriately determine the temperature detection value _Tx that should be the final measurement value _Tme , and maintain its accuracy.

Alternatively, the d- and q-axis current command values (i ^* _d , i ^* _q ) may be filtered (e.g., a first-order lag filter) in consideration of the transient characteristics of the current, and then the two-phase/three-phase conversion may be performed to obtain the estimated phase currents ( _{iu_es} , _{iv_es} , _{iw_es} ). This can further improve the accuracy of the final measurement value _Tme .

[Fourth embodiment]
The fourth embodiment will be described below, with the same elements as those in any of the first to third embodiments being given the same reference numerals and their description being omitted.

In this embodiment, a mode will be described in which the determination currents (I _ju , I _jv , I _jw ) are calculated based on the phase currents (i _u-k , _iv-k , i _w-k ) acquired at past control timings t _c- k (k=1, 2, ...) and the phase currents (i _u , _iv , i _w ) acquired at the current control timing t _c0 . Note that, for the sake of simplicity, "x" will be used below as a symbol representing each component of the UVW phases as appropriate.

In particular, in this embodiment, the microcomputer 11 calculates the difference between the phase current i _x-1 at the previous control timing t _c-1 and the phase current i _x0 at the current control timing t _c0 , and calculates the current change rate Δ _i from this difference and the unit control time Δt _smp . Furthermore, the microcomputer 11 calculates an estimate of the phase current i _x after a predetermined time Δt ₁ has elapsed since the calculated current change rate Δ _i and the current phase current i _x0 . The microcomputer 11 then sets the estimated value of the phase current i _x as the determination current I _jx . That is, the microcomputer 11 determines the determination current I _jx according to the following equations (1) and (2):

Δ _i = (i _{x_0} - _{i x_1} )/Δt _smp ...(1)
I _jx = i _{x_0} +Δ _i ×Δt ₁ ...(2)

Here, when the temperature detection value _Tx to be the final measured value _Tme is switched according to the control logic described in the first embodiment, etc., the processing related to the switching takes a certain amount of time. Therefore, it is expected that the timing at which the microcomputer 11 makes the switching decision (hereinafter also referred to as the "switching timing _tsw ") and the timing at which the microcomputer 11 acquires the final measured value _Tme after the switching is reflected (hereinafter also referred to as the "acquisition timing _tob ") may not fall within the same control period.

In this case, the magnitude comparison result of the judgment current _Ijx at the switching timing _tsw will differ from the magnitude relationship of each component of the actual phase current _ix at the switching timing _tsw , and it is possible that the accuracy of the obtained final measurement value _Tme will decrease.

In contrast, in the configuration of this embodiment, the determination current _Ijx is determined taking into consideration the behavior of the phase current _iuk (particularly the previous phase current _ix-1 ) acquired at the past control timing _tck to the phase current _ix0 acquired at the current control timing _tc0 , thereby making it possible to suppress a decrease in the accuracy of the final measurement value _Tme due to the above factors.

The effects of the control provided by this embodiment are explained in more detail below.

7A and 7B are diagrams illustrating the effects of this embodiment. In particular, Fig. 7A shows the change over time in the absolute value of each component of the phase current ( _iu , _iv , _iw ) when the control of this embodiment is not executed. On the other hand, Fig. 7B shows the change over time in the absolute value of each component of the phase current ( _iu , _iv , _iw ) when the control of this embodiment is executed. Furthermore, in each diagram, the phase currents ( _iu0 , _iv0 , _iw0 ) that are the subject of magnitude comparison at the switching timing _tsw (current control timing _tc0 ) are indicated by open triangle plots.

In the example shown in FIG. 7A, at the current control timing t _c0 (switching timing t _sw ), the V-phase current i _v is the largest current component. Therefore, according to the control logic described in the first embodiment, the V-phase temperature detection value T _v is determined as the final measurement value T _me . However, at the later acquisition timing t _{ob ,} the U-phase current i _u has changed to the largest current component. Therefore, although the temperature related to the U phase should be measured, the temperature related to the V phase is measured instead.

In contrast to this, in this embodiment, the determination _currents (I _ju0 , I _jv0 , I _jw0 ) that determine the final measurement value T me at the acquisition timing t _ob are calculated from the phase currents (i u0 , i v0 , i _w0 ) at the current control timing t _c0 and the phase currents (i _{u -1} , i _v-1 , i _{w -1} ) at the previous control timing t c- ₁ , which are indicated by the black triangular plot. As a result, at the acquisition timing t _ob , the maximum current component is determined to be the U-phase current i _u and the U-phase temperature detection value T _u is determined to be the final measurement value T _me , thereby ensuring measurement accuracy.

Fifth Embodiment
The fifth embodiment will be described below. Elements similar to those in any of the first to fourth embodiments are given the same reference numerals, and their description will be omitted.

In this embodiment, based on the control configuration of the second or third embodiment, the electrical angle θ _e is calculated based on the electrical angle θ _e-1 and motor rotation speed ω _r acquired at the previous control timing t _c-1 , and the unit control time Δt _smp .

In particular, the microcomputer 11 obtains the electrical angle θ _e after a predetermined time Δt ₁ has elapsed since the previous control timing t _c−1 according to the following equation (3).

θ _{e_pr} = θ _{e_c} + ω _r ×Δt ₁ ...(3)

As a result, when determining the determination current _Ijx , the electrical angle _θe is calculated taking into account the delay time from the switching timing _tsw to the acquisition timing _tob , and then the determination currents ( _Iju , _Ijv , _Ijw ) can be determined, thereby improving the accuracy of the final measurement value _Tme .

In particular, when employing a configuration in which estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ) are determined by performing two-phase/three-phase conversion on the dq-axis current command values (i ^* _d , i ^* _q ) described in the third embodiment, the electrical angle _θe used in the two-phase/three-phase conversion is more suited to actual behavior. Therefore, by using these estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ) as the determination currents (I _ju , I _jv , I _jw ), the accuracy of the obtained final measurement value T _me can be particularly improved. The above points will be described below with reference to more specific examples.

The effects of the control provided by this embodiment are explained in more detail below.

8A and 8B are diagrams illustrating the effects of this embodiment. In particular, Fig. 8A shows the change over time in the absolute value of each component of the phase current ( _iu , _iv , _iw ) when the control of this embodiment is not executed. On the other hand, Fig. 8B shows the change over time in the absolute value of each component of the phase current ( _iu , _iv , _iw ) when the control of this embodiment is executed.

In the example shown in FIG. 8A, at the current control timing t _c0 (switching timing t _sw ), the V-phase current i _v is the largest current component. Therefore, assuming the control logic of the second or third embodiment, the V-phase temperature detection value T _v is determined as the final measurement value T _me . However, at the later acquisition timing t _{ob ,} the U-phase current i _u has changed to the largest current component. Therefore, although the temperature related to the U phase should be measured, the temperature related to the V phase is measured instead.

In contrast, the absolute values of the estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ) obtained by the control logic of this embodiment behave as shown by the bold line in Figure 8(b). Based on these estimated phase currents (i _{u_es} , i _{v_es} , i _{w_es} ), the largest current component is determined to be the U-phase current _iu at both _the control timing t _c0 and the acquisition timing t _ob . In other words, the comparison results of the absolute values of the components of the determination currents (I _ju , I _jv , I _jw ) more reliably match at the control timing t c0 and the acquisition timing t _ob , thereby improving the accuracy of the final measurement value T _me .

Sixth Embodiment
The sixth embodiment will be described below. Elements similar to those in any of the first to fifth embodiments are designated by the same reference numerals, and their description will be omitted. In particular, in this embodiment, more specific aspects of the selection control determination process (step S520) and the measurement value determination process (step S540) described in FIG. 3 will be described.

9 is a flowchart illustrating the selection control determination process of this embodiment. In the selection control determination process, the microcomputer 11 first references the permission flag indicating a state in which execution of the first selection control is permitted, and determines whether or not the first selection control was executed at the previous control timing tc _-1 (step S521). If the microcomputer 11 determines that the first selection control was executed at the previous control timing tc _-1, it executes the process of step S522. If not, it executes the process of step S523.

In step S522, the microcomputer 11 determines whether the motor rotation speed _ωr is equal to or less than a predetermined first threshold value _ωrth1 . The first threshold value _ωrth1 is a reference value of the motor rotation speed _ωr for determining whether the operating point of the motor 30 is within a region of rotation speeds equal to or less than a certain value in which the first selection control should be maintained (hereinafter referred to as the "first low rotation region"), assuming that the first selection control was executed at the previous control timing tc- ₁ . The first threshold value _ωrth1 is determined in advance by experiment or simulation depending on the unit control time _Δtsmp and the characteristics of the motor 30, and is stored in any memory region accessible by the microcomputer 11.

If the microcomputer 11 determines that the motor rotation speed _ωr is equal to or less than the first threshold value _ωrth1 , it keeps the permission flag on (step S524) and ends the process. On the other hand, if the microcomputer 11 determines that the motor rotation speed _ωr is greater than the first threshold value _ωrth1 , it turns the permission flag off (step S525) and ends the process.

In step S523, the microcomputer 11 determines whether the motor rotation speed _ωr is equal to or less than a predetermined second threshold value _ωrth2 . The second threshold value _ωrth2 is a reference value of the motor rotation speed _ωr for determining whether the operating point of the motor 30 is within a region below a certain rotation speed (hereinafter referred to as the "second low rotation region") where control should be switched to first selection control, assuming that second selection control was executed at the previous control timing tc- ₁ . In particular, the second threshold value _ωrth2 is set to a value smaller than the first threshold value _ωrth1 . The second threshold value _ωrth2 is determined in advance by experiment or simulation depending on the unit control time _Δtsmp and the characteristics of the motor 30, and is stored in any storage area accessible by the microcomputer 11.

If the microcomputer 11 determines that the motor rotation speed _ωr is equal to or less than the second threshold value _ωrth2 , it switches the permission flag on (step S526) and ends the process. If the microcomputer 11 determines that the motor rotation speed _ωr exceeds the second threshold value _ωrth2 , it keeps the permission flag off (step S527) and ends the process.

Next, after completing the above-described selection control determination process, the microcomputer 11 executes a determination current setting process (step S530) based on any of the control logics described in the first to fifth embodiments, and then executes a measurement value determination process (step S560).

Figure 10 is a flowchart illustrating the measurement value determination process (step S560) of this embodiment. In the measurement value determination process, the microcomputer 11 first determines whether the permission flag is on.

If the microcomputer 11 determines that the permission flag is on, the microcomputer 11 proceeds to step S564, generates a command signal for determining the final measurement value _Tme in accordance with the first selection control, and ends this process. That is, the microcomputer 11 sets the temperature detection value _Tx selected based on the determination currents ( _Iju , _Ijv , _Ijw ) already described as the final measurement value _Tme .

On the other hand, if the microcontroller 11 determines that the permission flag is not on, it executes the second selection control in step S563.

In the second selection control of this embodiment, the microcomputer 11 generates a command signal to fix the temperature detection value T x-α, which was set as the final measurement value T me at a past control timing t _c at which the motor rotation _speed ω r exceeded the first threshold value ω _rth1 or the second threshold value ω _rth2 and which was the closest control timing t _{c -α} to the current control timing t _c0 (i.e., the timing immediately prior to the present when the threshold value _was not exceeded), as the final measurement value T _me thereafter.

As described above, in the measurement value acquisition method of this embodiment, the operating state parameters include the motor rotation speed _ωr . Then, in the measurement value determination process (step S560), it is determined whether to execute the first selection control or a predetermined basic selection control (second selection control) based on the motor rotation speed _ωr . In particular, when the second selection control is executed, the final measurement value _Tme is fixed to the temperature detection value _Tx of the phase that was the final measurement value _Tme at the previous control timing tc _-α .

In particular, in the selection control determination process (step S520) of this embodiment, if the first selection control was executed at the previous control timing t _c−1 (Yes in step S521), it is determined to execute the first selection control if the motor rotation speed ω _r is equal to or less than a predetermined first threshold value ω _rth1 determined according to the length of the unit control time Δt _smp , and it is determined to execute the second selection control if not.

This realizes a specific control logic that can suppress the decrease in accuracy of the final measurement value _Tme in the high rotation range that occurs when measurement is performed without taking into account the variations in the temperature increase rate of each phase in the low rotation range of the motor 30 described above.

On the other hand, if the second selection control was executed at the previous control timing tc _-1, the execution of the first selection control is determined when the motor rotation speed _ωr is equal to or less than a second threshold value _ωrth2 that is smaller than the first threshold value _ωrth1 , and otherwise the execution of the second selection control is determined.

This realizes a specific control logic that can resume the first selection control at an appropriate timing from the viewpoint of maintaining the accuracy of the final measurement value _Tme in the high rotation speed region of the motor 30.

More specifically, when the motor 30 is stopped and then goes through the low rotation region and then to the high rotation region, it is desirable to maintain the first selection control, which selects the detected temperature value _Tx based on the determination currents ( _Iju , _Ijv , _Ijw ), for as long as possible (i.e., to set the first threshold value _ωrth1 as high as possible). However, on the other hand, if the first threshold value _ωrth1 determined from the viewpoint of maintaining the first selection control for a long period of time is also used in determining whether to switch back from the second selection control to the first selection control, the detected phase temperature value _Tw determined as the final measured value _Tme may be frequently switched, which may lead to a decrease in measurement accuracy. This effect is particularly noticeable when employing a control logic that references the phase currents ( _iu-k , _iv-k , _iw-k ) acquired at past control timings tc _- k (k=1, 2, ...) as described in the fourth embodiment. In contrast, in the configuration of this embodiment, the determination to resume the first selection control is made using the second threshold value _ωrth2 that is smaller than the first threshold value _ωrth1 . Therefore, the first selection control is resumed when the operating point of the motor 30 enters a lower rotation range (the second low rotation range), and the deterioration of measurement accuracy due to the above-mentioned factors is suppressed.

The effects of this embodiment will be explained below using more specific examples.

Figure 11 is a diagram illustrating the effects of the control of this embodiment. In particular, Figure 11(a) shows an example when the control of this embodiment is not executed. On the other hand, Figure 11(b) shows an example when the control of this embodiment is executed.

11(a) and 11(b) show the phase corresponding to the detected temperature value Tx determined as the final measured value _Tme at each control timing _tc (switching timing _tsw ). The lower timing charts in FIG. 11(a) and 11(b) show a scenario in which the microcomputer 11 acquires the final measured value _{Tme ,} reflecting the switching decision at each switching timing _tsw , at the control timing _tc (acquisition timing _tob ) next to each switching timing _tsw .

Generally, the frequency of the phase current i _x increases as the rotation speed of the motor 30 increases. Therefore, depending on the operating state of the motor 30, a situation may arise in which the frequency of the phase current i _x becomes higher than a certain level for the unit control time Δt _smp . As a result, it is expected that a bias will occur in the comparison results of the magnitude of the absolute values of the components of the determination _currents (I _ju , I _jv , I _jw ) at the switching timing t sw.

More specifically, as shown in Figure 11(a), in the high rotation region (t≧ _t2 ) where the motor rotation speed _ωr increases over time and exceeds a certain value, the fluctuations in each component of the phase current ( _iu , _iv , _iw ) per unit time become large. Therefore, in this high rotation region, depending on the switching timing _tsw , the detected temperature value _Tx corresponding to a phase (e.g., U-phase) whose current absolute value is only temporarily large may be selected as the final measured value _Tme . In other words, the W-phase temperature detected value _Tw of the W-phase, which has the highest temperature, is not selected as the final measured value _Tme , resulting in a decrease in measurement accuracy.

In contrast, in the control of this embodiment, in accordance with the control logic of the above-described selective control determination process, the final measurement value _Tme after time t= _t2 when the motor rotation speed _ωr becomes equal to or greater than a certain value is fixed to the W-phase temperature detection value _Tw that was finally determined as the final measurement value _Tme before time t= _t2 . This prevents a decrease in measurement accuracy.

In particular, in the scene before the motor 30 reaches a certain rotation speed from a stopped state (the low rotation region from time t = 0 to t = ₂ in FIG. 11), the absolute values of certain components (W-phase current _iw and V-phase current _iv in FIG. 11) in the phase currents ( _iu , _iv , _iw ) tend to be unevenly large. As a result, the rate of increase in the temperature of the specific phase is higher than that of the other phases.

Therefore, since the difference in the temperature increase rate of each phase in the low rotation range of the motor 30 also affects the actual temperature in each phase thereafter, it is expected that continuing the first selection control in the high rotation range will result in a decrease in measurement accuracy.In contrast, with the control of this embodiment, once the motor 30 enters the high rotation range, the second selection control is executed and the temperature detection value _Tx, which is used as the final measurement value Tme _, is fixed, thereby suppressing a decrease in measurement accuracy.

Furthermore, once a certain amount of time has passed since the operating point of the motor 30 entered the high rotation range, the increase rates of the temperatures of the phases tend to become approximately equal to each other and move toward a state of equilibrium. Therefore, if a long time has passed since entering the high rotation range, the temperature difference between the phases when the motor 30 is stopped tends to directly affect the temperature difference in the equilibrium state. Therefore, in this case, a configuration may be adopted in which the temperature detection value _Tx selected when the motor 30 was stopped is fixed to the final measured value _Tme .

In this embodiment, the second selection control that is executed when the motor rotation speed _ωr is equal to or greater than a certain value and the first selection control is not permitted may be changed to the standard switching control described in the first embodiment.

Seventh Embodiment
The seventh embodiment will be described below. Elements similar to those in any of the first to sixth embodiments are designated by the same reference numerals, and their description will be omitted. In particular, this embodiment describes an example in which, when the motor rotation speed _ωr is equal to or greater than a certain value and the first selection control is not permitted (No in step S561), a second selection control (step S563) different from that in the sixth embodiment is executed.

12 is a flowchart illustrating the second selection control of this embodiment. In the second selection control, the microcomputer 11 first determines whether the phase corresponding to the temperature detection value T _x-1 related to the final measurement value T _me-1 acquired at the previous control timing t _c-1 (acquisition timing t _ob-1 ) (the phase that was the target of previous measurement) is the same as the phase corresponding to the temperature detection value T _x related to the final measurement value T _me to be acquired at the current control timing t _c0 (acquisition timing t _ob0 ) (the phase that is the current target of measurement) (step S5631). In other words, it determines whether the temperatures of the same phase are to be measured at the previous control timing t _c-1 and the current control timing t _c0 .

If the result of the determination is affirmative, the microcomputer 11 sets the temperature detection value _Tx of a specific phase as the final measurement value _Tme (step S5633). On the other hand, if the result of the determination is negative, the microcomputer 11 executes the process of step S5632.

In step S5632, the microcomputer 11 determines whether the final measurement value T _me at the current control timing t _c0 is smaller than the final measurement value T _me-1 at the previous control timing t _c-1 .

If the microcomputer 11 determines that the result of this determination is positive, it sets the same phase that was the previous measurement target as the subsequent measurement target. On the other hand, if the microcomputer 11 determines that the result of this determination is negative, it sets the phase that was not the previous or current measurement target as the subsequent measurement target.

As described above, in this embodiment, when the second selection control is executed, the temperature detection value T _x to be the final measurement value T _me is selected based on the comparison result between the final measurement value T _me-1 at the previous control timing t _c-1 and the final measurement value T _me0 at the current control timing t _c0 .

This allows the temperature of the phase with the highest temperature to be measured preferentially, even during second selection control, improving the accuracy of temperature measurement.

The effects of this embodiment will be explained below using more specific examples.

Figure 13 is a diagram explaining the effects of this embodiment.

In the example of FIG. 13 , in the low rotation region (t<t ₂ ), the W-phase temperature is continuously measured from the beginning. Then, when the rotation enters the high rotation region (t≧t ₂ ), the lowest U-phase temperature is measured according to the logic of step S5633 described above. Therefore, at each specific acquisition timing t _ob0 in FIG. 13 , the lowest U-phase temperature is measured. Meanwhile, according to the logic of steps S5631 and S5633 described above, at acquisition timing t _ob+1 following acquisition timing t _ob0 where the U-phase was measured, the W-phase is set as the measurement target, the same as at the previous acquisition timing t _ob-1 .

This allows measurements to be taken of the hot phase at least every other time in the high rotation range, improving measurement accuracy.

The above describes embodiments of the present invention, but these 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 embodiments.

Furthermore, the above embodiments can be combined with each other in any combination that does not cause contradictions.

The control program for causing a computer controller to execute the processes described in each of the above embodiments, and the storage medium storing the control program, are also included within the scope of the matters described in the specification, etc., of this application at the time of filing.

REFERENCE SIGNS LIST 10 Motor controller 11 Microcomputer 12 Temperature sensor 13 Multiplexer 20 Power adjustment unit 24 Switching element 30 Motor

Claims (7)

1. A measurement value acquisition method for determining one of physical quantity measurement values obtained at a plurality of measurement positions of an actuator controlled by a predetermined control device as a final measurement value to be used for controlling the actuator, comprising:
a setting step of determining an operating state parameter that indicates an operating state of the actuator correlated with each of the physical quantity measurements;
a determining step of determining the final measurement value by executing either a first selection control or a second selection control with reference to the operating state parameter;
the actuator includes a power adjusting unit that adjusts a phase current of an AC motor;
Each of the physical quantity measurement values is a temperature detection value of each phase of the power adjustment unit,
the operating state parameters include a determination current indicating the magnitude of a current of each phase and a rotation speed of the AC motor;
In the determining step,
determining whether to execute the first selection control or the second selection control based on a rotation speed of the AC motor;
In the first selection control, a phase in which the current is maximum is identified based on the determination current, and the temperature detection value detected in the identified phase is determined as the final measurement value;
In the second selection control, the temperature detection value of the phase determined as the final measurement value at a past control timing is fixed as the final measurement value ,
When the first selection control was executed at the previous control timing,
determining to execute the first selection control when the rotation speed of the AC motor is equal to or less than a predetermined first threshold value determined according to the length of a unit control time, and determining to execute the second selection control when the rotation speed is not equal to or less than a predetermined first threshold value;
When the second selection control was executed at the previous control timing,
determining to execute the first selection control when the rotation speed of the AC motor is equal to or less than a second threshold value that is smaller than the first threshold value, and determining to execute the second selection control when the rotation speed is not equal to or less than a second threshold value;
How measurements are taken. The measurement value acquisition method according to claim 1,
In the setting step,
The determination current is
the estimated value of the phase current is calculated based on the electrical angle of the AC motor.
How measurements are taken. The measurement value acquisition method according to claim 2,
The estimated value of the phase current is
a current command value for the AC motor is calculated using the electrical angle;
How measurements are taken. The measurement value acquisition method according to claim 1,
In the setting step,
The determination current is calculated based on the phase current acquired at a past control timing and the phase current acquired at a current control timing.
How measurements are taken. The measurement value acquisition method according to claim 2 or 3,
calculating the electrical angle based on the acquired electrical angle, the rotation speed of the AC motor, and a unit control time;
How measurements are taken. The measurement value acquisition method according to claim 1 ,
When the second selection control is executed,
The temperature detection value to be the final measurement value is
Selection is made based on a comparison result between the final measurement value at the previous control timing and the final measurement value at the current control timing.
How measurements are taken. 1. A measurement value acquisition device that determines one of physical quantity measurement values obtained at a plurality of measurement positions of an actuator controlled by a predetermined control device as a final measurement value to be used for controlling the actuator,
a setting unit that determines an operating state parameter that indicates an operating state of the actuator correlated with each of the physical quantity measurement values;
a determination unit that determines the final measurement value by executing either a first selection control or a second selection control with reference to the operating state parameter;
the actuator includes a power adjusting unit that adjusts a phase current of an AC motor;
Each of the physical quantity measurement values is a temperature detection value of each phase of the power adjustment unit,
the operating state parameters include a determination current indicating the magnitude of a current of each phase and a rotation speed of the AC motor;
The determination unit
determining whether to execute the first selection control or the second selection control based on a rotation speed of the AC motor;
In the first selection control, a phase in which the current is maximum is identified based on the determination current, and the temperature detection value detected in the identified phase is determined as the final measurement value;
In the second selection control, the temperature detection value of the phase determined as the final measurement value at a past control timing is fixed as the final measurement value ,
When the first selection control was executed at the previous control timing,
determining to execute the first selection control when the rotation speed of the AC motor is equal to or less than a predetermined first threshold value determined according to the length of a unit control time, and determining to execute the second selection control when the rotation speed is not equal to or less than a predetermined first threshold value;
When the second selection control was executed at the previous control timing,
determining to execute the first selection control when the rotation speed of the AC motor is equal to or less than a second threshold value that is smaller than the first threshold value, and determining to execute the second selection control when the rotation speed is not equal to or less than a second threshold value;
Measurement acquisition device.