Rotational position correction device, motor drive system, and rotational position correction method

Abstract

To provide a rotation position correction device, a motor driving system, and a method for correcting a rotation position that can make the result of detection of the angle of a shaft by a resolver less dependent on temperatures.SOLUTION: The rotation position correction device has a detection value correction unit. A motor detects the angle of a shaft by a resolver. The detection value correction unit corrects the angel detected value of the resolver corresponding to the temperature of the resolver, on the basis of the estimated value or the detected value of the temperature of the resolver changing according to the output of the motor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a rotational position correction device, a motor drive system, and a rotational position correction method. [Background technology]

[0002] A resolver is used to detect the angle of a rotating body connected to a shaft by detecting the angle (rotational position) of the shaft. The accuracy of the angle detection results can sometimes decrease depending on the ambient temperature of the resolver. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-263943 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide a rotational position correction device, a motor drive system, and a rotational position correction method that can reduce the temperature dependency of the detection result of the shaft angle by a resolver. [Means for solving the problem]

[0005] The device of the embodiment is attached to the shaft of the motor. Through flange The temperature estimator and the detection value corrector are connected to each other to correct the angle detection value output by the resolver that detects the angle of the shaft. The device includes a temperature estimator and a detection value corrector. The temperature estimation unit is configured to estimate a temperature within a range in which heat generated by the motor due to the power supplied from the power converter is conducted to the resolver. With the flange temperature at The above The resolver is The detection value correction unit generates an estimated value of the temperature of the resolver. Flanges Based on the estimated temperature of Flanges The angle detection value of the resolver is corrected using data that defines the relationship between the temperature and the phase error of the resolver. [Brief description of the drawings]

[0006] [Figure 1] 1 is a schematic configuration diagram of a motor drive system according to a first embodiment. [Diagram 2] 5 is a graph showing the relationship between the output magnitude and saturation temperature of the motor drive system according to the embodiment. [Diagram 3] FIG. 4 is a diagram showing the relationship between temperature and operation time of the motor drive system according to the embodiment. [Figure 4] 5A and 5B are diagrams for explaining temperature changes accompanying changes in the operating state of the motor drive system according to the embodiment. [Diagram 5] 5A and 5B are diagrams for explaining an angle detection value including an error depending on an ambient temperature in the embodiment. [Figure 6] 5A and 5B are diagrams for explaining a relationship between an ambient temperature and an error in an angle detection value according to the embodiment. [Figure 7] FIG. 11 is a schematic configuration diagram of a motor drive system according to a second embodiment. [Figure 8] FIG. 11 is a schematic configuration diagram of a motor drive system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] Hereinafter, a rotational position correction device, a motor drive system, and a rotational position correction method according to the embodiments will be described with reference to the drawings. Note that the drawings are schematic or conceptual, and the allocation of functions of each part is not necessarily the same as in reality.

[0008] In the following description, components having the same or similar functions are denoted by the same reference numerals, and redundant descriptions of those components may be omitted. In the embodiment, "connected" includes being electrically connected. "Based on XX" means "based on at least XX" and may include a case where it is based on another element in addition to XX. "Based on XX" is not limited to the case where XX is directly used, but may include a case where it is based on XX that has been calculated or processed. "XX or YY" is not limited to either one of XX and YY, but may include both XX and YY. This also applies to the case where there are three or more selective elements. "XX" and "YY" are any element (for example, any information). "Inverter" is a power converter that outputs AC, and includes, for example, a DC / AC converter. "Motor" is a rotating electric machine such as an induction motor that is driven by AC power. "Rotational speed of a motor" is sometimes simply called "speed of a motor".

[0009] In the following description, a "measured current value" refers to an actual measured current value, an index value indicating the actual magnitude of the current, or an estimated value indicating the magnitude of the current.

[0010] (First embodiment) 1 is a block diagram illustrating a motor drive system 1 including a rotational position correction device according to a first embodiment. For example, the motor drive system 1 includes a motor speed control device 10. The motor speed control device 10 is an example of a rotational position correction device. The motor drive system 1 may further include a motor 2 (denoted as M in FIG. 1) and a resolver 2A (denoted as SS in FIG. 1).

[0011] The motor speed control device 10 is connected to the motor 2 and a resolver 2A. The motor speed control device 10 calculates the actual speed of the motor 2 detected by the resolver 2A in accordance with a desired speed command value ω * The speed of Motor 2 is controlled to match

[0012] The motor 2 has a plurality of windings, each of which is connected to the output of an inverter 30, which will be described later. The inverter 30 is an example of a power converter. For example, the inverter 30 converts DC power supplied from a DC power source 20 (indicated as DC in the figure) to drive the motor 2. For example, when AC from the inverter 30 flows through each winding, the motor 2 rotates due to electromagnetic action. For example, the shaft of the motor 2 is mechanically connected to the shaft of the resolver 2A by a method such as flange coupling, and the shaft of the resolver 2A rotates in conjunction with the rotation of the shaft of the motor 2.

[0013] The resolver 2A generates an AC signal according to the position of its own shaft. For example, the resolver 2A detects the magnetic flux excited by the current in the primary winding with the secondary winding. The voltage or current excited in the secondary winding becomes an AC signal containing phase information according to the angle difference between the direction of the excited magnetic flux and the direction of the secondary winding. The resolver 2A generates the AC signal as a detection signal of the position of its own shaft. For example, the primary winding of the resolver 2A is fixed to its housing. The housing of the resolver 2A is fixed to, for example, a base common to the motor 2 or to the housing of the motor 2. Therefore, the positional relationship of each part may change within an allowable range depending on the temperature difference of the resolver 2A.

[0014] The resolver 2A of the embodiment includes a signal converter therein. The signal converter generates an index value indicating the angle of the axis of the resolver 2A, that is, an index value indicating the angle of the axis of the motor 2 (referred to as the angle detection value θe2) based on an AC signal corresponding to the position of its own axis. In other words, the resolver 2A generates and outputs the angle detection value θe2 corresponding to the detection result of the angle of the axis of the motor 2. The signal converter includes an electronic circuit for signal processing. Therefore, the output signal may include an offset that depends on the ambient temperature. In the following description, mechanical detection errors and electrical detection errors that depend on the ambient temperature are collectively described as errors due to changes in the temperature of the resolver 2A. The signal converter may be configured separately outside the resolver 2A, or may be included as a part of the motor speed control device 10 described later. In the following description, a case where the signal converter is built into the resolver 2A will be described.

[0015] For example, the motor speed control device 10 is a control device for an inverter 30 that drives the motor 2. The motor speed control device 10 is an example of a rotational position correction device.

[0016] The motor speed control device 10 includes a rotational position correction unit 3, a speed control unit 5, a current control unit 6, a PWM control unit 7 (PWM in the figure), a current value conversion unit 8, and a temperature estimation unit 9. The speed control unit 5, the current control unit 6, and the PWM control unit 7 are examples of the control unit. A general method may be applied to this control.

[0017] The speed control unit 5 determines a speed command value ω * A command value for the drive torque is generated by multiplying the speed deviation between the estimated speed value ωFBK of the motor 2 and the speed command value ω * is supplied from a higher-level control device such as a programmable controller (PLC). * A desired value is set and maintained at that value until the next value is set. The estimated speed value ωFBK of the motor 2 will be described later.

[0018] The current control unit 6 is connected to the output of the speed control unit 5. The current control unit 6 outputs a voltage command value V that is generated according to the difference between the command value of the driving torque supplied from the speed control unit 5 and an estimated value of the torque current component supplied to the motor 2 (referred to as a current iFBK). * Output.

[0019] The PWM control unit 7 drives the motor 2 by controlling the inverter 30 through PWM control (Pulse Width Modulation control). For example, the input of the PWM control unit 7 is connected to the output of the current control unit 6, and the output of the PWM control unit 7 is connected to the inverter 30. The PWM control unit 7 controls the inverter 30 based on the voltage command value V * In response to this, the inverter 30 outputs a gate control signal so as to drive the motor 2.

[0020] For example, a current transformer CT that detects the phase current of each phase may be provided in the wiring connected to the output of the inverter 30. The current transformer CT may be provided in at least two of the wirings of each phase of the three-phase AC.

[0021] The current value conversion unit 8 generates a current detection value iFBK that is an index value of the magnitude of the phase current, based on the instantaneous value of the phase current detected by the current transformer CT and a reference phase θ0 corresponding to the rotation of the motor 2. The current control unit 6 may perform current control using the current detection value iFBK.

[0022] The temperature estimation unit 9 estimates the temperature T of the motor 2 and resolver 2A of the motor drive system 1. For example, the temperature estimation unit 9 estimates the magnitude of the phase current (current detection value iFBK) and the voltage command value V * The temperature T is estimated based on the above. The details of this will be described later.

[0023] A first input of the rotational position correction unit 3 is connected to the output of the resolver 2A. For example, the rotational position correction unit 3 receives the angle detection value θe2 output from the resolver 2A and uses it for speed control of the motor 2. A second input of the rotational position correction unit 3 is connected to the output of the temperature estimator 9. For example, the rotational position correction unit 3 uses the temperature estimation value output by the temperature estimator 9 for rotational position correction.

[0024] For example, the rotational position correction unit 3 includes a detection value correction unit 31 and a speed conversion unit 32. The detection value correction unit 31 includes a correction value generation unit 31a and a subtractor 31b. The correction value generation unit 31a generates an angle correction value Δθt based on the temperature estimation value output by the temperature estimation unit 9. The subtractor 31b subtracts the angle correction value Δθt from the angle detection value θe2 to generate an angle estimation value θe1. The angle correction value Δθt is an example of angle correction information.

[0025] The speed conversion unit 32 acquires the angle estimate value θe1 ​​generated by the detection value correction unit 31, and generates the above-mentioned speed estimate value ωFBK and the like based on the angle estimate value θe1.

[0026] The motor speed control device 10 may include a processor such as a CPU, and the processor may execute a predetermined program to realize some or all of the functional units such as the rotational position correction unit 3, the speed control unit 5, the current control unit 6, the PWM control unit 7, the current value conversion unit 8, and the temperature estimation unit 9, or the above may be realized by a combination of electric circuits (circuitry). The motor speed control device 10 may use the storage area of ​​an internal storage unit to transfer each data and perform calculations for analysis by executing a predetermined program by the processor.

[0027] Next, the correction of the detected angle value will be described with reference to FIG. 2 to FIG. FIG. 2 is a diagram for explaining the relationship between the magnitude of the output of the motor drive system 1 of the embodiment and the saturation temperature. FIG. 3 is a diagram for explaining the relationship between the temperature and the time during which the motor drive system 1 of the embodiment is operated. FIG. 4 is a diagram for explaining the temperature change accompanying a change in the operating state of the motor drive system 1 of the embodiment. Note that the output of the motor drive system 1 refers to, for example, the power (output power) supplied to the motor 2. The magnitude of the output of the motor drive system 1 can be an index equivalent to the amount of power supplied to the motor 2.

[0028] Below, we will explain an example of correcting the deviation in the angle information generated in the detection result of the resolver 2A based on the temperature of the resolver 2A. The example shown below is applicable to cases where a temperature sensor is not installed or to environments where the temperature cannot be measured directly. In this case, it is advisable to predict the temperature and correct the deviation in the angle information.

[0029] During operation, the motor 2 generates heat due to losses. When the operating conditions of the motor 2 (the magnitude of the output of the motor drive system 1) change, the temperature of the motor 2 changes accordingly. The amount of heat generated by the motor 2 depends on the magnitude of the output of the motor drive system 1. The greater the magnitude of the output of the motor drive system 1, the greater the amount of heat generated. As the magnitude of the output of the motor drive system 1 changes, the temperature around them changes due to the heat generated by the motor 2 and other components. For example, if the output of the motor drive system 1 is maintained at a predetermined magnitude, it will saturate at a temperature determined by the magnitude of that output. The graph in Figure 2 shows the relationship between the magnitude of the output of the motor drive system 1 (horizontal axis) and the temperature TP at saturation (vertical axis). The relationship between the output P and the temperature TP shown in this graph can be modeled by approximating it with a linear equation, for example, as shown in the following equation (1).

[0030] TP = k P + Ta (1)

[0031] In the above formula (1), k is the temperature coefficient and Ta is the ambient temperature. This relationship may be defined in advance as a reference table. From the above formula (1), the temperature at which the temperature becomes saturated can be obtained, but if the change is slow, the transient state cannot be fully defined. Therefore, the temperature in the transient state is defined by the following method.

[0032] Figure 3 shows the relationship between the time t (horizontal axis) during operation of the motor drive system 1 and the ambient temperature (vertical axis). At the timing of the origin of the horizontal axis shown in Figure 3, the change in temperature when the magnitude of the output of the motor drive system 1 changes stepwise is shown. As described above, when the magnitude of the output of the motor drive system 1 changes, the temperature of the motor 2 and its surroundings changes accordingly. However, in this case, each part has its own thermal resistance and thermal capacity, and the change in temperature T tends to lag behind the change in output. For example, it is advisable to approximate and model the tendency of the change in temperature T in this case with a first-order lag system as shown in Figure 3 and the following equation (2).

[0033] T=(TP-T0)·(1-exp(-t / τ))+T0···(2)

[0034] In the above formula (2), τ is a time constant, and T0 is a temperature immediately before the temperature T changes. This relationship may be defined in advance as a reference table.

[0035] In the example shown in FIG. 4, the operating state of the motor drive system 1 is switched three times within the period shown in this figure. In the initial state of the period shown in this figure, the motor drive system 1 stops the supply of power to the motor 2, so no heat is generated from the motor 2. The initial temperature T is equal to the ambient temperature Ta.

[0036] At time t1, the first switching of the operating state is performed. The motor drive system 1 starts and maintains the supply of power amount P1 to the motor 2. When the power amount P1 is continuously supplied to the motor 2, it is expected that the ambient temperature will gradually rise until it reaches temperature T1. The relationship between the power amount P1 and temperature T1 may be derived from the correspondence relationship shown in FIG. 2 described above. Note that the next switching of the operating state may occur before the ambient temperature reaches temperature T1. In such a case, the trend of change in temperature T changes from that point (for example, time t2).

[0037] At time t2, the second switching of the operating state is performed. The motor drive system 1 starts supplying the amount of power P2 to the motor 2, switches the amount of power supplied, and then maintains this amount. When the amount of power P2 is continuously supplied to the motor 2, it is expected that the ambient temperature will gradually rise until it reaches temperature T2. The relationship between the amount of power P2 and temperature T2 may be derived from the correspondence relationship similarly shown in FIG. 2 above. Note that the next switching of the operating state may occur before the ambient temperature reaches temperature T2. In such a case, the trend of change in temperature T changes from that point (for example, time t3).

[0038] At time t3, the third switching of the operating state is performed. The motor drive system 1 starts supplying the amount of power P3 to the motor 2, switches the amount of power to be supplied, and then maintains this amount. If the amount of power P3 is continuously supplied to the motor 2, it is expected that the ambient temperature will gradually drop until it reaches temperature T3. The relationship between the amount of power P3 and temperature T3 may be derived from the correspondence relationship shown in FIG. 2 described above.

[0039] In this way, by modeling the relationship between the amount of power and the temperature, it is possible to correct the detected angle value that includes an error that depends on the temperature T that changes with a time delay. A more specific example will be described with reference to Figs. 5 and 6.

[0040] FIG. 5 is a diagram for explaining an angle detection value including an error depending on temperature T in the embodiment. FIG. 5 shows the relationship between the physical angle θrm (horizontal axis) and the detection value θe (vertical axis). For example, in a practical situation where the detection value θe does not include an error, the detection value θe coincides with the physical angle θrm. The detection value θe in such a state is shown by a solid line. In contrast, in a situation where the detection value θe includes an error depending on temperature T, the error ΔθT included in the detection value θe becomes apparent as an offset component for the physical angle θrm. The detection value θe in such a state is shown by a dashed line. This error ΔθT shows a tendency that is clearly different from the component whose value changes randomly for each measurement.

[0041] For example, in a configuration capable of detecting an angle range from 0° to 360°, when the physical angle θrm of the shaft of the motor 2 to be detected by the resolver 2A is θm, if no error ΔθT is included, the detected value θe at that time will be the detected value θe1, which is equal to the θm of the physical angle θrm. In contrast, if an error ΔθT is included, the detected value θe at that time will be the detected value θe2, which is different from the θm of the physical angle θrm. As shown in the following equation (3), the difference between the detected value θe1 ​​and the detected value θe2 is the error ΔθT. Since this tendency occurs regardless of the shaft angle, roughly the same amount of error ΔθT will be included at any angle.

[0042] ΔθT = θe2 - θe1 (3)

[0043] The detection value θe2 in the situation shown in Fig. 5 above includes an error ΔθT of an offset component that depends on temperature T. The relationship between temperature T and the error ΔθT of an offset component that depends thereon will be described with reference to Fig. 6. Fig. 6 is a diagram for explaining the relationship between temperature and an error of an angle detection value in the embodiment. Fig. 6 shows the relationship between temperature T (horizontal axis) and error θT of an angle detection value (vertical axis).

[0044] Since there is a trend between the temperature T and the error θT of the detected angle value as shown in this graph, it is advisable to model the relationship between the temperature T and the error ΔθT of the detected angle value by approximating it with a linear equation, for example, as shown in the following equation (4).

[0045] ΔθT=a (T_est-T_ref)+b (4)

[0046] In the above formula (4), T_est is the predicted temperature, T_ref is the reference temperature (e.g., 25°C), and a and b are predetermined constants. Note that a corresponds to the slope of the graph in Figure 6, and b corresponds to the intercept of the graph in Figure 6. It has become clear that the above procedure makes it possible to analytically derive an estimate of the error ΔθT in the angle detection value.

[0047] Therefore, as shown in the following equation (5), by using an estimated value of the error ΔθT in the detected angle value as a compensation amount θc for the detected angle value θe2, it is possible to obtain the detected angle value θe1 ​​by correcting the detected angle value θe2.

[0048] θe1=θe2-θc=θe2-ΔθT ···(5)

[0049] Using the above principle, the correction process may be realized, for example, according to the following procedure. The temperature estimation unit 9 estimates the magnitude of the phase current (current detection value iFBK) and the voltage command value V * Based on this, the temperature T is derived using the above equations (1), (2), etc. The detection value correction unit 31 of the rotational position correction unit 3 derives an estimate of the error ΔθT of the detected angle value by using the formula (4). The detection value correction unit 31 uses this as a compensation amount θc for the detected angle value θe2 to derive the detected angle value θe1 ​​by correcting the detected angle value θe2. The speed conversion unit 32 generates a speed estimate value ωFBK based on the angle estimate value θe1 ​​generated by the detection value correction unit 31. The speed control unit 5, the current control unit 6, and the PWM control unit 7 are configured to calculate the speed estimation value ωFBK in accordance with the speed command value ω *The motor 2 is controlled so as to achieve the above. The speed control unit 5, the current control unit 6, and the PWM control unit 7 are an example of a control unit that controls the motor 2. The above procedure makes it possible to correct the detection result of the resolver 2A.

[0050] According to the above embodiment, the motor speed control device 10 (rotational position correction device) includes a detection value correction unit 31. The detection value correction unit 31 corrects the angle detection value of the resolver 2A corresponding to the temperature based on an estimated value or a detected value of the temperature of the resolver 2A that changes depending on the output of the motor 2. This enables the motor speed control device 10 to reduce the temperature dependency of the detection result of the shaft angle by the resolver 2A.

[0051] (First Modification of the First Embodiment) In the above embodiment, one method for estimating the temperature T of the resolver 2A has been described as an example, but the method is not limited to this. In this modified example, a case will be described in which the position for defining the temperature T is set to a specific position. For example, the specific position is set to a flange portion of the shaft of the resolver 2A. In this case, it is preferable that the detection value correction unit 31 holds in advance data on the relationship between the temperature Tf of the flange portion on the resolver 2A side and the error ΔθT of the angle detection value. This makes it possible to deal with the phase error (error ΔθT) caused by heat conduction from the bearing of the motor 2 through its shaft and the flange portion in a similar manner.

[0052] (Second Modification of the First Embodiment) In addition, in this modified example, instead of estimating the temperature T of the resolver 2A, the temperatures of the motor 2 body, the resolver 2A body, the flange connecting the shaft of the motor 2 and the shaft of the resolver 2A, etc. may be detected during operation, and the result may be used as the temperature T of the resolver 2A.

[0053] Second embodiment A second embodiment will be described with reference to FIG. 7. The configuration of the first embodiment uses one resolver 2A. In this embodiment, instead, a case will be described in which a plurality of resolvers 2A are used to provide a redundant configuration for the rotation detection part. The number of resolvers 2A is not limited to the following example and may be determined arbitrarily.

[0054] FIG. 7 is a schematic configuration diagram of a motor drive system according to the second embodiment. The motor drive system 1A includes, for example, a resolver 2B in addition to the resolver 2A of the motor drive system 1. The resolver 2B has the same configuration as the resolver 2A. Reference numerals are changed for the sake of explanation. The motor drive system 1A includes a motor speed control device 10A instead of the motor speed control device 10.

[0055] The motor speed control device 10A may correct the angle detection values ​​of the resolver 2A and the resolver 2B by using a common correction amount for the detection results of the resolver 2A and the resolver 2B. Alternatively, the motor speed control device 10A may correct the angle detection values ​​of the resolver 2A and the resolver 2B by using mutually different correction amounts for the detection results of the resolver 2A and the resolver 2B.

[0056] The latter will be explained in more detail below. The motor speed control device 10A is connected to the motor 2, and to the resolvers 2A and 2B. The motor speed control device 10A calculates a speed command value ω * At that time, the motor speed control device 10A switches between the detection results of the resolver 2A and the resolver 2B.

[0057] Instead of the rotational position correction unit 3, speed control unit 5, and temperature estimator 9 of motor speed control unit 10, motor speed control device 10A includes rotational position correction units 3A and 3B, a speed control unit 5A, and temperature estimators 9A and 9B.

[0058] Rotational position correction units 3A and 3B are each configured similarly to rotational position correction unit 3, for example. A detection value correction unit 31A of the rotational position correction unit 3A is connected to the output of the resolver 2A, generates an angle correction value Δθt based on the temperature TA estimated by the temperature estimation unit 9A, and generates a corrected angle estimate value θe1A using this. A speed conversion unit 32A of the rotational position correction unit 3A generates a speed estimate value ωFBKA based on the angle estimate value θe1A.

[0059] Similarly, a detection value correction unit 31B (not shown) of the rotational position correction unit 3B is connected to the output of the resolver 2B, generates an angle correction value Δθt based on the temperature TB estimated by the temperature estimation unit 9B, and generates a corrected angle estimate value θe1B using this. A speed conversion unit 32B (not shown) of the rotational position correction unit 3B generates a speed estimate value ωFBKB based on the angle estimate value θe1B. The detection value correction units 31A and 31A correspond to the detection value correction unit 31 described above. The speed conversion units 32A and 32B correspond to the speed conversion unit 32 described above.

[0060] The speed control unit 5A controls the speed command value ω * and the speed estimate value ωFBKA of motor 2, or the speed command value ω * and the speed estimate value ωFBKB of the motor 2 are multiplied by a predetermined speed response gain to generate a command value for the drive torque. For example, the speed control unit 5A is configured to select and use either the speed deviation ΔωA or the speed deviation ΔωB for system switching of the redundant configuration.

[0061] According to this embodiment, by providing the resolvers 2A and 2B and the rotational position correction units 3A and 3B with a redundant configuration as described above, it is possible to provide the motor drive system 1A with a redundant configuration.

[0062] (Modification of the second embodiment) An example of a redundant configuration has been described in the second embodiment. In this modification, an example in which there is an individual difference in characteristics between the resolver 2A and the resolver 2B will be described. There may be cases where the detection results of the resolvers 2A and 2B contain errors due to individual differences in characteristics. The detection value correction units 31A and 31B perform correction to absorb the individual differences in the characteristics of the resolvers, thereby absorbing the individual differences in the characteristics of the resolvers 2A and 2B.

[0063] In addition, when the resolver 2A and the resolver 2B are affected by the heat of the motor 2 to different degrees, this can be absorbed. For example, when the resolver 2A and the resolver 2B are arranged at different positions on the axis of the motor 2 in a direction away from the motor 2, the heat generated by the motor 2 and transmitted to the resolver 2A is greater than the heat transmitted to the resolver 2B. In such a case, a temperature difference occurs between the temperatures of the resolver 2A and the resolver 2B. The detection value correction unit 31A and the detection value correction unit 31B may each calculate the angle correction value Δθt that includes this temperature difference as a condition.

[0064] (Third embodiment) A third embodiment will be described with reference to Fig. 8. The motor drive system 1 of the first embodiment has been described as a basic case in which the calculation standard of the correction amount is fixed. In this embodiment, a motor drive system 1B will be described in which the calculation standard of the correction amount can be switched depending on the driving situation.

[0065] FIG. 8 is a schematic configuration diagram of a motor drive system according to the third embodiment. The motor drive system 1B includes a motor speed control device 10B instead of the motor speed control device 10 of the motor drive system 1.

[0066] The motor speed control device 10B further comprises a history information processing unit 4 in comparison with the motor speed control device 10, and comprises a rotational position correction unit 3C instead of the rotational position correction unit 3.

[0067] The history information processing unit 4 includes, for example, a history information recording processing unit 41, a history information analysis processing unit 42, a control characteristic switching processing unit 43, and a storage unit 44.

[0068] The history information recording processing unit 41 records control information indicating the control state in the storage unit 44 as needed to generate history information.

[0069] The history information analysis processing unit 42 analyzes the history information recorded in the storage unit 44 to detect, for example, changes over time or sudden changes. A statistical analysis method applicable to abnormality detection may be applied as a method for detecting these changes. For example, when it is detected that the detection characteristics of the resolver 2A have changed from the past, the control characteristic switching processing unit 43 controls the rotational position correction unit 3C to change the angle correction value Δθt for the detection result of the resolver 2A to one suitable for the current characteristics.

[0070] The rotational position correction unit 3C includes a detection value correction unit 31C replacing the detection value correction unit 31. The detection value correction unit 31C corresponds to the detection value correction unit 31. The detection value correction unit 31C further switches the angle correction value Δθt under the control of the history information analysis processing unit 42. This switching makes the angle correction value Δθt suitable for the current characteristics.

[0071] The method of changing to one suitable for the current characteristics may be a method of selecting from among predetermined candidates, or a method of generating an angle correction value Δθt based on the current detection result and switching to the newly generated angle correction value Δθt.

[0072] According to this embodiment, by comparing the data on the operating state and the amount of correction of the angle actually corrected with past data in the history information, it is possible to find changes in the detection characteristics of the resolver 2A. The data on the curve corresponding to the changes in the detection characteristics of the resolver 2A can be updated to deal with changes over time.

[0073] According to at least one of the embodiments described above, the rotational position correction device includes a detection value correction unit. A shaft angle of a motor is detected by a resolver. The detection value correction unit corrects a resolver angle detection value corresponding to the temperature based on an estimated value or a detected value of the resolver temperature that changes depending on the output of the motor. This allows the rotational position correction device to reduce the temperature dependency of the detection result of the shaft angle by the resolver.

[0074] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope of the invention and its equivalents described in the claims, as well as in the scope and spirit of the invention. [Explanation of symbols]

[0075] 1, 1A, 1B motor drive system, 2 motor, 3, 3A, 3B, 3C rotational position correction unit, 4 history information processing unit, 5, 5A speed control unit, 6 current control unit, 7 PWM control unit, 8 current value conversion unit, 9, 9A temperature estimation unit, 10 motor speed control device (rotational position correction device), 20 DC power supply, 30 inverter, 31, 31A, 31B, 31C detection value correction unit, 32, 32A, 32B speed conversion unit

Claims

1. A device for correcting an angle detection value output by a resolver that is connected to a motor shaft via a flange and detects the angle of the shaft, comprising: a temperature estimation unit that generates an estimate of the temperature of the resolver from a detected value of the temperature of the flange by using a temperature of the flange within a range where heat of the motor generated by electric power supplied from a power converter is conducted to the resolver; a detection value correction unit that corrects an angle detection value of the resolver by using data that defines a relationship between the temperature of the flange and a phase error of the resolver based on an estimated value of the temperature of the flange that is related to a temperature change of the resolver; A rotational position correction device comprising:

2. A motor drive system that detects an angle of a motor shaft using a resolver, a power converter for supplying power to the motor; An apparatus according to claim 1; a control unit that controls the motor using the angle detection value corrected by the device; A motor drive system comprising:

3. a motor whose shaft angle is detected by the resolver; The resolver and The motor drive system of claim 2 .

4. A method for correcting an angle detection value output by a resolver that is connected to a motor shaft via a flange and detects the angle of the shaft, comprising the steps of: generating an estimate of the temperature of the resolver from the detected temperature of the flange using a temperature of the flange within a range where heat of the motor generated by the electric power supplied from a power converter is conducted to the resolver; a step of correcting an angle detection value of the resolver using data that defines a relationship between the temperature of the flange and a phase error of the resolver, based on an estimated value of the temperature of the flange that is related to a temperature change of the resolver; A rotational position correction method comprising:

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