control device

Abstract

To enable prevention of a decrease in stability.SOLUTION: A control device which is mounted on a vehicle including a motor for traveling includes a processing unit and a storage unit. When a first predetermined timing arrives, the processing unit sets a stored value stored in the storage unit at a predetermined parameter related to drive control over the motor and executes current estimation processing for an estimate value related to the predetermined parameter using the stored value as an initial value. When a second predetermined timing arrives, the processing unit causes the storage unit to store the estimate value in the current estimation processing as the stored value.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a control device.

Background Art

[0002] Conventionally, in a control device that generates a voltage command value by a current control unit from a current command value and a current value detected by a current sensor, there has been proposed a control device that inputs the voltage command value to a plant model unit to calculate a virtual current value, inputs the virtual current value to a periodic disturbance observer via a coordinate conversion unit to calculate a compensation value, and superimposes the calculated compensation value on the detected current value via an inverse coordinate conversion unit to correct the detected current value of the current sensor (see, for example, Patent Document 1). In this control device, a value obtained by superimposing the detected current value and the compensation value, and the detected current value are input to a current sensor error estimation unit to calculate an offset error and a gain error, and the error of the current sensor is estimated based on each of the calculated error signals.

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Summary of the Invention

Problem to be Solved by the Invention

[0004] In such a control device, if some of the various parameters related to drive control of a motor are sequentially updated, there are cases where the update is performed to a value with a large error, which may lead to a decrease in stability of the drive control of the motor.

[0005] A main object of the control device of the present disclosure is to suppress a decrease in stability of drive control of a motor.

Means for Solving the Problem

[0006] The control device of the present disclosure adopts the following means to achieve the above main object.

[0007] [1] The control device of this disclosure is A control device mounted on a vehicle equipped with a motor for driving, comprising a processing unit and a memory unit, The aforementioned processing unit, When the first predetermined timing is reached, the stored value in the memory unit is set to a predetermined parameter related to the drive control of the motor, and the current estimation process is performed on the estimated value related to the predetermined parameter using the stored value as the initial value. When the second predetermined timing is reached, the estimated value from the estimation process is stored in the storage unit as the stored value. This is the gist of it.

[0008] In the control device of this disclosure, when the first predetermined timing is reached, the processing unit sets the stored value in the memory unit to a predetermined parameter related to motor drive control, and uses the stored value as an initial value to perform the current estimation process for the estimated value related to the predetermined parameter. Furthermore, when the second predetermined timing is reached, the processing unit stores the estimated value from the current estimation process as a stored value in the memory unit.Therefore, by setting the stored value to the predetermined parameter each time the first predetermined timing is reached, that is, by holding the predetermined parameter from the current first predetermined timing until the next first predetermined timing, it is possible to avoid sequential updates (frequent updates) of the predetermined parameter and suppress a decrease in the stability of motor drive control.In addition, by using the stored value as an initial value to perform the current estimation process for the estimated value related to the predetermined parameter, it is possible to suppress the time it takes for the estimated value to converge in the current estimation process from becoming longer.

[0009] Here, the predetermined parameters may be parameters that are assumed to be unlikely to undergo abrupt changes, specifically, parameters that are assumed to have gradual change characteristics (changes where the rate of change, which is the amount of change per unit time, is less than or equal to a predetermined rate of change) in the interval between the first predetermined timing and the second predetermined timing, or between the current first predetermined timing and the next first predetermined timing. Through diligent research, the inventors have confirmed that sequentially updating parameters that are assumed to be unlikely to undergo abrupt changes tends to lead to a decrease in the stability of the motor drive control. The estimation process for the predetermined parameters may be a process that prioritizes the convergence of the estimated value over responsiveness to the vicinity of the true value, specifically, a process that has low responsiveness to the vicinity of the true value but good convergence of the estimated value.

[0010] [2] In the control device of the present disclosure (the control device described in [1] above), when the second predetermined timing is reached, the processing unit may store the estimated value in the storage unit as the stored value if the estimated value in the current estimation process is within an acceptable range, but may not store the estimated value in the storage unit if the estimated value in the current estimation process is outside the acceptable range.

[0011] [3] In the control device of the present disclosure (the control device described in [1] or [2] above), the first predetermined timing includes at least one of the timing at which the vehicle's system is instructed to start, the timing at which the vehicle is stopped by a brake operation, and the timing at which a torque command used for drive control of the motor crosses a torque threshold, and the second predetermined timing may include at least one of the timing at which the vehicle's system is instructed to stop, and the timing at which a predetermined time has elapsed from the first predetermined timing.

[0012] [4] In the control device of the present disclosure (the control device described in any one of [1] to [3] above), the predetermined parameter may be a correction value based on at least one of the gain error of a current sensor that detects the phase current of each phase of the motor, and the offset error of the current sensor. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram of an electric vehicle 20 equipped with a control device according to an embodiment. [Figure 2] This flowchart shows an example of a processing routine executed by the CPU 51 of the electronic control unit 50. [Figure 3] This is an explanatory diagram showing an example of how the corrected value ΔId and the corrected estimated value ΔIdc appear. [Figure 4] A flowchart shows an example of a processing routine for a modified case. [Modes for carrying out the invention]

[0014] Embodiments for implementing this disclosure will be described with reference to the drawings. Figure 1 is a schematic diagram of an electric vehicle 20 equipped with a control device according to an embodiment of this disclosure. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36 as an energy storage device, and an electronic control unit 50 as a control device.

[0015] The motor 32 is configured as a three-phase AC motor and comprises a rotor with permanent magnets embedded in the rotor core and a stator with three-phase coils wound around the stator core. The rotor of the motor 32 is connected to a drive shaft 26 which is connected to the drive wheels 22a and 22b via a differential gear 24.

[0016] The inverter 34 is used to drive the motor 32 and is connected to the battery 36 via a power line 38. The inverter 34 comprises six switching elements, transistors T11 to T16, and six diodes D11 to D16, each connected in parallel to the six transistors T11 to T16. The transistors T11 to T16 are arranged in pairs, with two on each side acting as the source and sink sides with respect to the positive and negative lines of the power line 38. Each connection point of a pair of transistors T11 to T16 is connected to each of the three-phase (U-phase, V-phase, W-phase) coils of the motor 32. Therefore, when voltage is applied to the inverter 34, the electronic control unit 50 adjusts the ratio of the on-times of the paired transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coils of the motor 32 and driving the motor 32 (rotor) to rotate.

[0017] The battery 36 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the inverter 34 via the power line 38 as described above. Smoothing capacitors 39 are attached to the positive and negative terminal lines of the power line 38.

[0018] The electronic control unit 50 includes a microcomputer having a CPU 51, a ROM 52, a RAM 53, a flash memory 54, an input / output port, and a communication port. The electronic control unit 50 receives signals from various sensors via the input port. For example, the electronic control unit 50 receives a rotational position θm from a rotational position sensor 32a that detects the rotational position of the rotor of the motor 32, phase currents Iu, Iv, Iw from current sensors 32u, 32v, 32w that detect the phase current of each phase of the motor 32, and a temperature αm from a temperature sensor 32t that detects the temperature of the motor 32. The electronic control unit 50 also receives a voltage Vb from a voltage sensor 36v mounted between terminals of the battery 36, a current Ib from a current sensor 36i mounted at an output terminal of the battery 36, a temperature αt from a temperature sensor 36t mounted on the battery 36, and a voltage VH of the capacitor 39 (power line 38) from a voltage sensor 39a mounted between terminals of the capacitor 39. The electronic control unit 50 also receives an on-off signal from a power switch 60, a shift position SP from a shift sensor 62 that detects an operation position of a shift lever 61, an accelerator opening Acc from an accelerator pedal position sensor 64 that detects a depression amount of an accelerator pedal 63, a brake pedal position BP from a brake pedal position sensor 66 that detects a depression amount of a brake pedal 65, and a vehicle speed V from a vehicle speed sensor 67.

[0019] The electronic control unit 50 outputs various control signals via the output port. For example, the electronic control unit 50 outputs control signals to transistors T11 to T16 of the inverter 34. The electronic control unit 50 calculates an electrical angle θe and a rotation speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 from the rotational position sensor 32a. The electronic control unit 50 calculates a state of charge SOC of the battery 36 based on an integrated value of the current Ib of the battery 36 from the current sensor 36i.

[0020] In the electric vehicle 20 of the embodiment configured as described above, the electronic control unit 50 (CPU 51) sets a required torque Td* required for the drive shaft 26 based on the accelerator opening Acc and the vehicle speed V, sets the torque command Tm* for the motor 32 such that the set required torque Td* is output to the drive shaft 26, and performs switching control of the transistors T11 to T16 of the inverter 34 such that the motor 32 is driven in accordance with the torque command Tm*.

[0021] The electronic control unit 50 basically controls the inverter 34 by pulse width modulation (PWM) control. In PWM control, first, using the electrical angle θe based on the rotational position θm of the rotor of the motor 32 obtained from the rotational position sensor 32a, coordinate transformation (three-phase to two-phase transformation) is performed on the phase currents Iu, Iv, Iw of each phase of the motor 32 obtained from the current sensors 32u, 32v, 32w, to calculate the d-axis and q-axis currents Id, Iq. Subsequently, sensor error correction using correction values ΔId, ΔIq is performed on the d-axis and q-axis currents Id, Iq to calculate corrected d-axis and q-axis currents Idco, Iqco. The correction values ΔId, ΔIq are parameters for correcting the d-axis and q-axis currents Id, Iq in consideration of sensor errors (offset errors and gain errors) of the current sensors 32u, 32v, 32w, and are part of various parameters related to drive control of the motor 32. Details of the correction values ΔId, ΔIq will be described later. Then, d-axis and q-axis current commands Id*, Iq* are set based on the torque command Tm* of the motor 32. In addition, d-axis and q-axis voltage commands Vd*, Vq* are calculated by current feedback control such that the difference between the corrected d-axis and q-axis currents Idco, Iqco and the current commands Id*, Iq* is canceled out, and coordinate transformation (two-phase to three-phase transformation) is performed on the calculated d-axis and q-axis voltage commands Vd*, Vq* using the electrical angle θe of the motor 32 to calculate phase voltage commands Vu*, Vv*, Vw for each phase. PWM signals for the transistors T11 to T16 are generated by comparing the thus obtained phase voltage commands Vu*, Vv*, Vw for each phase with a carrier wave (triangular wave), and switching control of the transistors T11 to T16 is performed using the generated PWM signals.

[0022] Here, we will explain the details of the correction values ​​ΔId and ΔIq. Figure 2 is a flowchart showing an example of a processing routine executed by the CPU 51 of the electronic control unit 50. This routine starts executing when a first predetermined timing is reached. Here, the first predetermined timing is the timing when the power switch 60 is turned on (the timing when the vehicle system startup is instructed).

[0023] When the processing routine in Figure 2 is executed, the CPU 51 first sets the stored values ​​ΔIdm and ΔIqm stored in the flash memory 54 to the corrected values ​​ΔId and ΔIq (step S100). Here, immediately after the vehicle is manufactured, the stored values ​​ΔIdm and ΔIqm are set to predetermined nominal values ​​(design values) ΔId0 and ΔIq0, and are subsequently updated by the processing in step S140 described later. As described above, the corrected values ​​ΔId and ΔIq are used to control the drive of the motor 32, specifically to perform sensor error correction using the corrected values ​​ΔId and ΔIq on the currents Id and Iq of the d and q axes and to calculate the corrected currents Idco and Iqco of the d and q axes.

[0024] Next, the CPU 51 sets the stored values ​​ΔIdm and ΔIqm to initial values ​​ΔIdi and ΔIqi (step S110), and uses the set initial values ​​ΔIdi and ΔIqi to perform the estimation process for the corrected estimated values ​​ΔIdc and ΔIqc related to the corrected values ​​ΔId and ΔIq (step S120). Here, the estimation process for the corrected estimated values ​​ΔIdc and ΔIqc can be, for example, regression analysis or smoothing. Examples of regression analysis include the least squares method and the nonlinear least squares method. Examples of smoothing include the Kalman filter. Note that the specific calculation methods for the corrected estimated values ​​ΔIdc and ΔIqc are well known, so a detailed explanation is omitted.

[0025] Then, the CPU 51 determines whether or not the second predetermined timing has been reached (step S130), and if it determines that the second predetermined timing has not been reached, it returns to step S120. Here, the second predetermined timing is the timing when the power switch 60 is turned off (the timing when the vehicle system is instructed to stop). If it is determined in step S130 that the second predetermined timing has been reached, the corrected estimated values ​​ΔIdc and ΔIqc at that time are stored in the flash memory 54 as stored values ​​ΔIdm and ΔIqm, thereby updating the stored values ​​ΔIdm and ΔIqm (step S140), and this routine ends.

[0026] Here, the sensor errors (offset errors and gain errors) of the current sensors 32u, 32v, and 32w depend on manufacturing variations and aging of the current sensors 32u, 32v, and 32w, and are not expected to change abruptly. Specifically, it is assumed that the interval between the first predetermined timing and the second predetermined timing, and the interval between the previous first predetermined timing and the current first predetermined timing, will have gradual change characteristics (change characteristics where the rate of change, which is the amount of change per unit time, is less than or equal to a predetermined rate of change). Therefore, the correction values ​​ΔId and ΔIq based on the sensor errors of the current sensors 32u, 32v, and 32w are parameters that are not expected to change abruptly. For this reason, if the correction values ​​ΔId and ΔIq are updated sequentially (updated frequently), it may be updated to values ​​with large errors, which could actually lead to a decrease in the stability of the drive control of the motor 32. In contrast, in this embodiment, the correction values ​​ΔId and ΔIq are updated each time a first predetermined timing is reached. That is, the correction values ​​ΔId and ΔIq are maintained from the time the current first predetermined timing is reached until the next first predetermined timing, thereby suppressing a decrease in the stability of the drive control of the motor 32. Furthermore, by using the stored values ​​ΔIdm and ΔIqm as initial values ​​ΔIdi and ΔIqi to perform the current estimation process for the correction estimated values ​​ΔIdc and ΔIqc, it is possible to suppress the length of time required for the correction estimated values ​​ΔIdc and ΔIqc to converge in the current estimation process.

[0027] Figure 3 is an explanatory diagram showing an example of how the corrected value ΔId and the corrected estimated value ΔIdc are handled. Although not shown in the diagram, the corrected value ΔIq and the corrected estimated value ΔIqc can be considered in the same way as the corrected value ΔId and the corrected estimated value ΔIdc. In the diagram, times t11, t13, and t15 are the first predetermined timings (the timing when the vehicle system is instructed to start), and times t12 and t14 are the second predetermined timings (the timing when the vehicle system is instructed to stop). That is, times t11-t12, t13-t14, and t15- correspond to the respective trips. As shown in the diagram, when the first predetermined timing is reached (times t11, t13, and t15), the stored values ​​ΔIdm and ΔIqm are set to the corrected values ​​ΔId and ΔIq, and estimation processing for the corrected estimated values ​​ΔIdc and ΔIqc is performed using the stored values ​​ΔIdm and ΔIqm as initial values ​​ΔIdi and ΔIqi. Subsequently, when the second predetermined timing is reached (times t12, t14), the corrected estimated values ​​ΔIdc, ΔIqc are set to the stored values ​​ΔIdm, ΔIqm, and the stored values ​​ΔIdm, ΔIqm are updated. During the estimation process for the corrected estimated values ​​ΔIdc, ΔIqc, the corrected estimated values ​​ΔIdc, ΔIqc may fluctuate relatively large. Therefore, if the corrected values ​​ΔId, ΔIq are updated sequentially using the corrected estimated values ​​ΔIdc, ΔIqc, the corrected values ​​ΔId, ΔIq may change abruptly, potentially leading to a decrease in the stability of the motor 32's drive control. In contrast, in this embodiment, by retaining the corrected values ​​ΔId, ΔIq from the current first predetermined timing to the next first predetermined timing, sequential updates (frequent updates) of the corrected values ​​ΔId, ΔIq can be avoided, and a decrease in the stability of the motor 32's drive control can be suppressed. Furthermore, in this estimation process for the corrected estimated values ​​ΔIdc and ΔIqc, by using the stored values ​​ΔIdm and ΔIqm, which were set with the corrected estimated values ​​(previous ΔIdc) and (previous ΔIqc) from the previous estimation process, as the initial values ​​ΔIdi and ΔIqi, it is possible to suppress the increase in the time it takes for the corrected estimated values ​​ΔIdc and ΔIqc to converge in this estimation process, compared to using the nominal values ​​ΔId0 and ΔIq0 as the initial values ​​ΔIdi and ΔIqi each time.

[0028] In the electronic control unit 50 mounted on the electric vehicle 20 of this embodiment described above, when the CPU 51 reaches a first predetermined timing, it sets the stored values ​​ΔIdm and ΔIqm as correction values ​​ΔId and ΔIq, and uses the stored values ​​ΔIdm and ΔIqm as initial values ​​ΔIdi and ΔIqi to perform estimation processing for the corrected estimated values ​​ΔIdc and ΔIqc. Then, when the second predetermined timing is reached, it updates the stored values ​​ΔIdm and ΔIqm by storing the corrected estimated values ​​ΔIdc and ΔIqc as stored values ​​ΔIdm and ΔIqm in the flash memory 54. This avoids sequential updates (frequent updates) of the correction values ​​ΔId and ΔIq, and suppresses a decrease in the stability of the drive control of the motor 32. It also suppresses the time required for the corrected estimated values ​​ΔIdc and ΔIqc to converge during the estimation process.

[0029] In the embodiment described above, the CPU 51 updates the stored values ​​ΔIdm and ΔIqm by storing the corrected estimated values ​​ΔIdc and ΔIqc as stored values ​​ΔIdm and ΔIqm in the flash memory 54 when it reaches the second predetermined timing, as shown in the processing routine of Figure 2. However, it is not limited to this. For example, the CPU 51 may execute the processing routine of Figure 4 instead of the processing routine of Figure 2. The processing routine of Figure 4 differs from the processing routine of Figure 2 in that the processing in step S132 is added. In the processing routine of Figure 4, when it is determined in step S130 that the second predetermined timing has been reached, it is determined whether the corrected estimated values ​​ΔIdc and ΔIqc in the current estimation process are within an acceptable range (step S132). Here, as the acceptable range, for example, a range that can normally be taken or a range of a predetermined change amount relative to the corrected estimated values ​​(previous ΔIdc) and (previous ΔIqc) in the previous estimation process can be used. If the corrected estimated values ​​ΔIdc and ΔIqc obtained in this estimation process are determined to be within the acceptable range, the corrected estimated values ​​ΔIdc and ΔIqc are stored in the flash memory 54 as stored values ​​ΔIdm and ΔIqm (step S140), and this routine terminates. On the other hand, if the corrected estimated values ​​ΔIdc and ΔIqc obtained in this estimation process are determined to be outside the acceptable range, this routine terminates without storing the corrected estimated values ​​ΔIdc and ΔIqc in the flash memory 54 as stored values ​​ΔIdm and ΔIqm. This avoids setting abnormal values ​​for the stored values ​​ΔIdm and ΔIqm.

[0030] In the embodiments described above, the first predetermined timing is the timing when the power switch 60 is turned ON (the timing when the vehicle system is instructed to start), and the second predetermined timing is the timing when the power switch 60 is turned OFF (the timing when the vehicle system is instructed to stop). However, the embodiments are not limited to these. For example, as the first predetermined timing, in addition to or instead of the timing when the vehicle system is instructed to start, the timing when the vehicle stops due to the operation of the brake pedal 65, and / or the timing when the torque command Tm* of the motor 32 crosses the threshold Tmref may be used. As the second predetermined timing, in addition to or instead of the timing when the vehicle system is instructed to stop, a predetermined time has elapsed from the first predetermined timing (for example, several minutes to several tens of minutes) may be used.

[0031] In the embodiment described above, the correction values ​​ΔId and ΔIq were based on the sensor errors (offset error and gain error) of the current sensors 32u, 32v, and 32w, but are not limited to this. For example, the correction values ​​ΔId and ΔIq may be based on only one of the offset error and gain error of the current sensors 32u, 32v, and 32w, or they may be based on the sensor error of the rotational position sensor 32a.

[0032] In the embodiment described above, a battery 36 is used as the energy storage device, but the invention is not limited to this. For example, a capacitor may be used as the energy storage device.

[0033] In the embodiments described above, the electronic control unit 50, as a control device, is mounted on an electric vehicle 20 equipped with a motor 32 for driving and an inverter 34 that drives it, but it is not limited to this. For example, the control device may be mounted on a hybrid vehicle which further includes an engine in addition to the same hardware configuration as the electric vehicle 20, or on a fuel cell vehicle which further includes a fuel cell in addition to the same hardware configuration as the electric vehicle 20.

[0034] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the CPU 51 corresponds to the "processing unit" and the flash memory 54 corresponds to the "storage unit".

[0035] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0036] Although the embodiments for implementing this disclosure have been described above, this disclosure is not limited in any way to these embodiments, and it is of course possible to implement it in various forms without departing from the gist of this disclosure. [Industrial applicability]

[0037] This disclosure can be used in industries such as the manufacturing of control devices. [Explanation of Symbols]

[0038] 20 Electric vehicle, 22a, 22b Drive wheels, 24 Differential gear, 26 Drive shaft, 32 Motor, 32a Rotation position sensor, 32t Temperature sensor, 32u, 32v, 32w, 36i Current sensor, 34 Inverter, 36 Battery, 36t Temperature sensor, 36v, 39a Voltage sensor, 38 Power line, 39 Capacitor, 50 Electronic control unit, 51 CPU, 52 ROM, 53 RAM, 54 Flash memory, 60 Power switch, 61 Shift lever, 62 Shift sensor, 63 Accelerator pedal, 64 Accelerator pedal position sensor, 65 Brake pedal, 66 Brake pedal position sensor, 67 Vehicle speed sensor, D11~D16 Diode, T11~T16 Transistor.

Claims

1. A control device mounted on a vehicle equipped with a motor for driving, comprising a processing unit and a memory unit, The aforementioned processing unit, When the first predetermined timing is reached, the stored value in the memory unit is set to a predetermined parameter related to the drive control of the motor, and the current estimation process is performed on the estimated value related to the predetermined parameter using the stored value as the initial value. When the second predetermined timing is reached, the estimated value from the estimation process is stored in the storage unit as the stored value. Control device.

2. A control device according to claim 1, When the second predetermined timing is reached, the processing unit, if the estimated value in the current estimation process is within the acceptable range, stores the estimated value in the storage unit as the stored value; if the estimated value in the current estimation process is outside the acceptable range, does not store the estimated value in the storage unit. Control device.

3. A control device according to claim 1 or 2, The first predetermined timing includes at least one of the timing at which the vehicle's system is instructed to start, the timing at which the vehicle comes to a stop due to brake operation, and the timing at which the torque command used for drive control of the motor crosses a torque threshold. The second predetermined timing includes at least one of the timing at which the vehicle's system is instructed to shut down, and the timing at which a predetermined time has elapsed from the first predetermined timing. Control device.

4. A control device according to claim 1 or 2, The predetermined parameter is a correction value based on at least one of the gain error of the current sensor that detects the phase current of each phase of the motor, and the offset error of the current sensor. Control device.

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