Drive device and motor control method

Abstract

The invention relates to a driving device and a control method of a motor, which can give consideration to responsiveness and efficient driving. The drive device includes: a power converter that converts input power into AC power and supplies the AC power to a motor; a voltage control unit that applies a drive voltage from the power converter to the motor by controlling the operation of the power converter; and a phase adjustment unit that adjusts the phase of the drive voltage by executing a first process for advancing the phase of the drive voltage and a second process for delaying the phase of the drive voltage. The phase adjustment unit executes: a first phase control process for receiving first information relating to a relationship between a phase of a current flowing through the motor and a rotational position of the motor, and adjusting a phase of the drive voltage on the basis of the first information; and a second phase control process for receiving second information relating to the magnitude of the current flowing in the motor and third information relating to the rotational speed of the motor, and adjusting the phase of the drive voltage on the basis of the second information and the third information.

Description

Technical Field

[0001] Embodiments of the present invention relate to a drive device and a method for controlling a motor. Background Art

[0002] In order to improve the efficiency of the motor system, synchronous motors using permanent magnets are widely used, and various motor control methods have been proposed. Examples of control methods for improving efficiency include a method of adjusting the voltage phase so that the induced voltage phase of the motor is consistent with the current phase, a method of adjusting the voltage phase so that the current of the motor becomes smaller, and the like.

[0003] Patent Document 1: Japanese Patent No. 6935349 Summary of the invention

[0004] One embodiment of the present invention provides a drive device and a control method of a motor that have excellent responsiveness and achieve high efficiency of a motor.

[0005] The driving device of the embodiment includes a power converter, a voltage control unit, and a phase adjustment unit. The power converter converts input power into AC power and supplies it to the motor. The voltage control unit controls the operation of the power converter, thereby applying a driving voltage from the power converter to the motor. The phase adjustment unit performs a first process of advancing the phase of the driving voltage and a second process of delaying the phase of the driving voltage to adjust the phase of the driving voltage. The phase adjustment unit performs: a first phase control process, receiving first information related to the relationship between the phase of the current flowing in the motor and the rotational position of the motor, and adjusting the phase of the driving voltage based on the first information; and a second phase control process, receiving second information related to the magnitude of the current flowing in the motor and third information related to the rotational speed of the motor, and adjusting the phase of the driving voltage based on the second information and the third information. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a vector diagram of an electric motor using permanent magnets.

[0007] Figure 2 This is a vector diagram of an electric motor using permanent magnets.

[0008] Figure 3 This is a waveform diagram showing the relationship between the induced voltage of the motor and the current of the motor.

[0009] Figure 4 This is a vector diagram of an electric motor using permanent magnets.

[0010] Figure 5It is a block diagram showing a driving device and a driving system according to the first embodiment.

[0011] Figure 6 This is a flowchart for explaining the driving operation of the driving device according to the first embodiment.

[0012] Figure 7 1 is a flowchart showing a first phase control process of the driving device according to the first embodiment.

[0013] Figure 8 1 is a flowchart showing the advance angle processing of the drive device according to the first embodiment.

[0014] Fig. 9 1 is a flowchart showing the delay angle processing of the drive device according to the first embodiment.

[0015] Fig.10 : is a flowchart showing the second phase control process of the driving device according to the first embodiment.

[0016] Fig.11 This is a waveform diagram showing an example of current detection using a shunt resistor.

[0017] Fig.12 1 is a flowchart showing a first phase control process of the driving device according to the second embodiment.

[0018] Explanation of symbols

[0019] 1: power converter, 3: return diode, 4: motor, 5: rotor position detection unit, 6: current detection unit, 7: rotation speed calculation unit, 8: voltage control unit, 9: phase adjustment unit, 10: current value processing unit, 11: operation command setting unit, 12: integrated circuit, DRV: drive device, SYS: drive system. DETAILED DESCRIPTION

[0020] Hereinafter, the embodiments will be described with reference to the accompanying drawings. In the description, the same reference numerals are attached to the components having substantially the same functions and structures. In addition, the embodiments shown below are used to illustrate the technical ideas. The embodiments do not particularly limit the materials, shapes, structures, configurations, etc. of the components. Various changes can be made to the embodiments.

[0021] (First Embodiment)

[0022] First, the outline of the drive control of the electric motor will be described. Figure 1 as well as Figure 2 This is a vector diagram of an electric motor using permanent magnets. Figure 1 as well as Figure 2 The magnetic flux vector Φ of the motor rotor is MThe vector diagram in the coordinate system is a vector diagram in which the direction of action is set as the d-axis and the direction perpendicular to the d-axis is set as the q-axis. Figure 1 as well as Figure 2 In each of them, except for the magnetic flux vector Φ M In addition, a drive voltage vector V applied from a power converter (inverter) to the motor, an induced voltage vector E of the motor, and a current vector I flowing through the motor are also shown.

[0023] Figure 1 The state in which the drive voltage V is applied to the motor so that the drive voltage vector V is in phase with the induced voltage vector E is shown. In this case, the phase difference θ between the current vector I flowing in the motor and the induced voltage vector E is θa. The current vector I is in a state of being delayed by the phase difference θa with respect to the induced voltage vector E.

[0024] Figure 2 The figure shows a state where the drive voltage V is applied to the motor in a state where the drive voltage vector V is advanced by a phase δa relative to the phase δ of the induced voltage vector E in order to make the current vector I and the induced voltage vector E coincide with each other in phase. Figure 2 In the state, the driving voltage changes from Figure 1 In this case, the driving voltage vector V is advanced by a phase δa relative to the induced voltage vector E, so that the current vector I of the motor becomes in the same phase with the induced voltage vector E. Therefore, the phase difference θ of the current vector I with respect to the induced voltage vector E becomes zero.

[0025] Here, the torque T in the surface magnet type motor is M is expressed as equation (1) using the number of pole pairs P of the motor, the current I and the phase difference θ. In equation (1), the magnetic flux Φ of the motor is M And the current I flowing in the motor is represented by a scalar.

[0026]

Formula 1

[0027] T M =P×Φ M ×I×cosθ (1)

[0028] On the right side of equation (1), the number of pole pairs P and the magnetic flux Φ M Here, assuming that the current I is also constant, the torque T can be made M The maximum value of cosθ is 1 when θ = 0 rad. That is, in a surface magnet type motor, Figure 2 When the conditions of the vector diagram shown in the figure are met, the maximum torque can be obtained.M In the case of θ=0 rad, the current I can be minimized and the efficiency can be improved.

[0029] Figure 3 It is a waveform diagram showing the relationship between the induced voltage of the motor and the current of the motor. The horizontal axis of the waveform diagram represents the time. The vertical axis represents the value of the voltage or current. Figure 3 In FIG. 1 , the waveform of the induced voltage E of the motor and the waveform of the current I of the motor are shown in a row. In addition, the current I is represented by a solid line when the current I and the induced voltage E are in the same phase, and by a dotted line when the phase of the current I is delayed compared to the induced voltage E. In the surface magnet type motor, the highest efficiency is obtained by making the phase of the induced voltage E consistent with the phase of the current I. In contrast, when the phase of the current I is delayed relative to the phase of the induced voltage E, the efficiency deteriorates, and the current I becomes larger than when the phase of the induced voltage E is consistent with the phase of the current I. The same is true when the phase of the current I is advanced relative to the phase of the induced voltage E. The phase of the current I can be adjusted to advance or delay by the phase of the driving voltage V. That is, it is sufficient to adjust the phase of the driving voltage V in such a way that the phase of the current I is consistent with the phase of the induced voltage E. Specifically, it is sufficient to control the phase of the driving voltage V in such a way that if the phase of the current I is delayed, the phase of the driving voltage V is advanced, and if the phase of the current I is advanced, the phase of the driving voltage V is delayed. This control is relatively simple and has excellent responsiveness. As a method for determining the phase, for example, the following method can be considered: the slope of the waveform of the current I is obtained by taking the timing when the induced voltage E becomes a positive peak as a reference. In this case, when the phase of the current I is delayed relative to the phase of the induced voltage E, the slope becomes positive, and when the phase of the current I is advanced relative to the phase of the induced voltage E, the slope becomes negative. In this way, by determining the timing that becomes the reference and detecting the slope of the waveform of the current I, it is possible to determine the delay or advance of the phase.

[0030] On the other hand, the torque T of the buried magnet type motor M It is expressed by formula (2).

[0031]

Formula 2

[0032] T M =P×{Φ M -(L q -L d )×I×sinθ}×I×cosθ (2)

[0033] In equation (2), inductance Ld is the inductance of the d-axis component. Inductance Lq is the inductance of the q-axis component. The embedded magnet type motor has salient polarity, so the relationship of Lq>Ld is achieved. In the case of the surface magnet type motor, since there is no salient polarity, Lq=Ld, so the term including (Lq-Ld) in equation (2) becomes 0, and equation (2) becomes equivalent to equation (1).

[0034] Figure 4 This is a vector diagram of an electric motor using permanent magnets. Figure 4 In the figure, the magnetic flux vector Φ of the motor rotor is M The direction of action is defined as the d-axis, and the direction perpendicular to the d-axis is defined as the q-axis. Figure 4 In, with Figure 1 as well as Figure 2 The phase of the driving voltage vector V is further advanced compared to the case, and the phase offset is set to δb, thereby making the phase of the motor current vector I advance the phase θb ​​compared to the induced voltage vector E. Here, as an efficient control method for embedded magnet type motors, MTPA (Maximum Torque Per Ampere) control is known, in which the motor flux is set to Φa, and the optimal phase θc of the motor current is expressed by equation (3).

[0035]

Formula 3

[0036]

[0037] The result of equation (3) becomes positive, so the optimum phase θc of the current I of the embedded magnet type motor is as follows: Figure 4 As shown in FIG. 1 , the phase θ is advanced relative to the induced voltage E. In addition, in equation (3), the phase θ depends on the current I, so the optimal phase θc of the current I of the embedded magnet type motor changes depending on the load and the operating state. In addition, the control of combining the phase of the induced voltage E and the phase of the current I is a control with θ=0 rad as the target, so in the embedded magnet type motor whose optimal phase is not 0 rad, the highest efficiency cannot be obtained by this control.

[0038] However, the formula for obtaining the optimal phase θ of the current I in the embedded magnet type motor shown in formula (3) includes square roots and division. When constructing the drive system of the motor, it will not be a problem when using a CPU (Central Processing Unit) with relatively high processing performance, but when it is to be constructed using a cheap and small IC (Integrated Circuit) with relatively low processing power, installation is more difficult. As a method for obtaining the optimal phase θc of the current I of the embedded magnet type motor without performing square roots and division, for example, the following method is listed. If based on the principle of MTPA, it is sufficient to maximize the torque relative to the current I, or minimize the current I relative to the torque. Therefore, the torque T M Ratio I / T to current I M As an indicator.

[0039] In the index I / T M The torque T is included M However, as shown in equations (1) and (2), in order to express torque, it is necessary to set information such as motor flux and inductance. In motor control using an IC with relatively low processing power, it is difficult to process multiple parameters. Therefore, we focus on the motion equation of the motor shown in equation (4). In addition, M represents the motor inertia constant, ω represents the angular velocity, and T M Indicates the motor output torque, T L represents the load torque, ΔT is the deviation between the motor output torque and the load torque (i.e. T M -T L ).

[0040]

Formula 4

[0041]

[0042] Here, when formula (4) is transformed from the perspective of the change in speed relative to an arbitrary time, that is, when the term of partial differentiation of ω by t is replaced by Δω / Ts and the formula is further transformed, formula (5) is obtained. In addition, Δω is the speed deviation and Ts is the control period.

[0043]

Formula 5

[0044]

[0045] In equation (5), the control period Ts and the motor inertia constant M are constants, so the speed deviation Δω and the torque deviation ΔT are proportional. M In the equation (5), the torque T is replaced by the speed ω based on the relationship M , which can be used as the current I relative to the torque TM The ratio of the equivalent index η is processed as in formula (6).

[0046]

Formula 6

[0047]

[0048] By adjusting the phase of the drive voltage V in a manner that reduces the index based on the index obtained according to formula (6), the current I can be guided to the optimal phase. In addition, although the formula (6) includes division, the control system has a count value N (N is a positive integer, equivalent to the reciprocal of the speed) for observing the elapsed time of an arbitrary period in the control process of obtaining the speed ω. Therefore, the index can be expressed by multiplication as shown in the following formula (7).

[0049]

Formula 7

[0050] η=I×N (7)

[0051] The method for adjusting the phase of the current I based on the indicator η is to determine the control direction in the next operation cycle according to the changes in the indicator η after executing the processing of advancing the phase (adjusting in the direction of advancing the phase of the driving voltage) or the processing of delaying the phase (adjusting in the direction of delaying the phase of the driving voltage) according to the guidelines in the following table.

[0052]

Table 1

[0053] The previous phase advance process The previous phase delay process Index η decreases Phase Advance Processing Phase delay processing Index η increases Phase delay processing Phase Advance Processing

[0054] As shown in Table 1, when the index η decreases and the process of advancing the phase was performed last time, the process of advancing the phase is performed. When the index η decreases and the process of delaying the phase was performed last time, the process of delaying the phase is performed. When the index η increases and the process of advancing the phase was performed last time, the process of delaying the phase is performed. When the index η increases and the process of delaying the phase was performed last time, the process of advancing the phase is performed.

[0055] In addition, by repeating the process from advancing the phase to delaying the phase, or from delaying the phase to advancing the phase in a short time by the above method, the phase of the current I can be considered to be near the optimal value. The change from the process of advancing the phase to the process of delaying the phase, or from the process of delaying the phase to the process of advancing the phase is defined as the number of inflection points Ninfle, and by setting an arbitrary upper limit value for the number of times, the phase control is converged (ended) after a certain trial repetition. Since the trial is repeated in this way, it takes time for this method to converge. In addition, when the process of advancing the phase or the process of delaying the phase is repeated for a certain number of times, the number of inflection points Ninfle is reset to 0 to prevent it from converging to a value other than the optimal phase.

[0056] Thus, as a method of phase control when driving a motor, there are a method of making the phase of the induced voltage E coincide with the phase of the current I and a method of minimizing the index η. The former has excellent responsiveness, and the latter can efficiently drive even an embedded magnet type motor. In the first embodiment, by combining these two control methods, a drive device that has excellent responsiveness and can efficiently drive a motor is realized.

[0057] A driving device according to a first embodiment for realizing these controls and a driving system including the driving device and a motor will be described. Figure 5 1 is a block diagram showing a driving device and a driving system according to the first embodiment. Figure 5 As shown, the drive system SYS includes an electric motor 4 and a drive device DRV.

[0058] The motor 4 is a three-phase synchronous motor. The motor 4 includes a rotor. The motor 4 is driven by the drive device DRV, and the rotor rotates.

[0059] The drive device DRV is a device for driving the motor 4. The drive device DRV includes a power converter 1, a rotor position detector 5, a current detector 6, a rotation speed calculator 7, a voltage controller 8, a phase adjuster 9, a current value processor 10, and an operation command setting unit 11.

[0060] The power converter 1 converts a DC voltage into an AC voltage of an arbitrary voltage and frequency. The power converter 1 includes, for example, 6 IGBTs (Insulated Gate Bipolar Transistors) 2 and 6 return diodes 3. The 6 IGBTs 2 are connected in a three-phase bridge configuration to form a so-called inverter circuit. The return diodes 3 are respectively provided between the collector and emitter of each IGBT 2, with the anode connected to the emitter and the cathode connected to the collector. A DC voltage is supplied to the power converter 1 from a DC power supply Vdc serving as a driving power supply. The three output terminals (three-phase output terminals) of the power converter 1 are respectively connected to a corresponding one of the three stator coils (three-phase stator coils) of the motor 4.

[0061] The rotor position detection unit 5 detects the position (rotational position) of the rotor of the motor 4. For example, the rotor position detection unit 5 includes a rotary encoder or a Hall sensor mounted on the motor 4, and detects the position of the rotor based on the output of the rotary encoder or the Hall sensor. The phase of the three-phase induced voltage E generated in the motor 4 is detected by detecting the position of the rotor. Information related to the position of the rotor, that is, information related to the phase of the three-phase induced voltage E generated in the motor 4, is sent to the rotation speed calculation unit 7, the voltage control unit 8, and the current value processing unit 10.

[0062] The current detection unit 6 detects the current I flowing in the motor 4. The current detection unit 6 detects the current I for one or more phases of the motor 4. The current detection unit 6 includes a shunt resistor or a current sensor, etc. In this embodiment, a so-called one-shunt method in which a shunt resistor is arranged at one point of the power line on the negative side (ground side) of the power converter 1 is described as an example.

[0063] The rotation speed calculation unit 7 calculates the rotation speed based on the amount of change in the rotation position. The rotation speed calculation unit 7 calculates the rotation speed based on the information on the position of the rotor received from the rotor position detection unit 5 and sends it as a count value N to the phase adjustment unit 9.

[0064] The current value processing unit 10 processes information related to the current detected by the current detection unit 6. The current value processing unit 10 includes a zero crossing detection circuit and a peak holding circuit. Based on the information related to the current I, the current value processing unit 10 checks the zero crossing at which the current I switches from positive to negative, or the zero crossing at which the current I switches from negative to positive. Then, the current value processing unit 10 recognizes the start and end of one cycle of the current I based on the detected zero crossing. In addition, the current value processing unit 10 detects the peak value Ip of the current I in one cycle. The current value processing unit 10 detects the peak value Ip for each cycle. The current value processing unit 10 sends the information related to the cycle of the current and the peak value Ip to the phase adjustment unit 9. In addition, the current value processing unit 10 detects the slope of the waveform of the current I, in other words, the direction of change of the current I with respect to the passage of time. Based on the information related to the phase of the induced voltage E received from the rotor position detection unit 5, the current value processing unit 10 detects the slope of the waveform of the current I in accordance with the timing of the peak value of the induced voltage E, for example. Detecting the slope of the waveform of the current I means determining whether the current I is increasing or decreasing with respect to the passage of time. The current value processing unit 10 sends information on the slope of the waveform of the current I to the phase adjustment unit 9 .

[0065] The phase adjustment unit 9 determines the phase shift amount based on the information related to the rotation speed and / or the information related to the current. The phase adjustment unit 9 receives the information related to the rotation speed from the rotation speed calculation unit 7 and the information related to the current I from the current value processing unit 10. Based on this information, the phase adjustment unit 9 calculates the phase shift amount according to how the phase of the driving voltage V should be set relative to the phase of the induced voltage E, and sends the calculated phase shift amount to the voltage control unit 8.

[0066] The operation command setting unit 11 sets the command related to the operation of the motor 4. The operation command setting unit 11 includes, for example, a user interface, and the command related to the operation of the motor 4 is set by the user or the like. The command set by the operation command setting unit 11 is sent to the voltage control unit 8. For example, the duty ratio is set by the operation command setting unit 11, and the set duty ratio is sent to the voltage control unit 8. As the user interface provided in the operation command setting unit 11, a touch panel, an operation button, or a remote controller can be listed.

[0067] The voltage control unit 8 controls the power converter 1 to supply AC power from the power converter 1 to the motor 4. The voltage control unit 8 controls the on / off of each of the six IGBTs 2 included in the power converter 1, thereby causing the power converter 1 to convert the DC power supply Vdc into an AC voltage of an arbitrary voltage and frequency, and output it to the motor 4. That is, the voltage control unit 8 controls how the power converter 1 outputs the drive voltage V. The control of the six IGBTs 2 by the voltage control unit 8 is based on the information related to the position of the rotor received from the rotor position detection unit 5, the phase shift amount received from the phase adjustment unit 9, and the duty ratio received from the operation command setting unit 11.

[0068] The rotation speed calculation unit 7, the voltage control unit 8, the phase adjustment unit 9, and the current value processing unit 10 are installed in, for example, an integrated circuit 12. The integrated circuit 12 is an IC (Integrated Circuit) chip. The integrated circuit 12 includes a processor and a storage medium. The integrated circuit 12 can be a microcomputer including a CPU, an ASIC (Application Specific Integrated Circuit), or an FPGA (Field Programmable Gate Array). The integrated circuit 12 including the processor performs the processing described later by executing a program stored in a storage medium, etc.

[0069] Figure 6 1 is a flowchart for explaining the driving operation of the driving device according to the first embodiment. The driving operation is an operation in which the driving device DRV drives the electric motor 4 .

[0070] When the driving action starts (start), the phase adjustment unit 9 initializes each variable (S61). Specifically, the variables Pa, Pb, C, ηa, ηb, Stage, and α are initialized to 0, respectively, and the number of inflection points Ninfle is initialized to -1. Variables Pa and Pb are variables used in the advance angle processing and the delay angle processing described later. Variable Pa is a variable indicating whether the processing executed this time is the advance angle processing or the delay angle processing. In the case of the advance angle processing, 1 is substituted, and in the case of the delay angle processing, -1 is substituted. Variable Pb is a variable indicating whether the processing executed last time is the advance angle processing or the delay angle processing. In the case of the advance angle processing, 1 is substituted, and in the case of the delay angle processing, -1 is substituted. Variable C is a variable whose count increases when the processing that advances the phase is continuously executed, or when the processing that delays the phase is continuously executed. Variables ηa, ηb, Stage, and α are variables used in the second phase control processing described later. The value obtained by accumulating the index η shown in formula (7) multiple times is stored in the variable ηa. The variable ηb stores the accumulated value held by the variable ηa before resetting the variable ηa in order to accumulate the current variable ηa. The variable Stage stores the stage in which the phase adjustment is in progress. The details of each Stage will be described later. The variable α is a variable indicating the passage of a cycle, and is incremented by 1 or reset to 0 when the processing of each Stage is executed. The number of inflection points Ninfle is a variable whose count increases when switching from a process that advances the phase to a process that delays the phase or from a process that delays the phase to a process that advances the phase. In addition, the purpose of initializing the number of inflection points Ninfle to -1 instead of 0 is to offset the effect of the increase in the number of inflection points Ninfle when one of the advance angle processing or the delay angle processing described later is executed for the first time.

[0071] Next, the phase adjustment unit 9 determines whether the inflection point number Ninfle is less than 1 (S62). By determining whether the inflection point number Ninfle is less than 1, it is possible to determine whether the current phase is near the optimal phase. In addition, the number 1 compared with the inflection point number Ninfle in S62 is a threshold value, which may be 2 or 3, for example. The threshold value compared with the inflection point number Ninfle in S62 can be set to any value.

[0072] When the number of inflection points Ninfle is less than 1 (S62, yes), the phase adjustment unit 9 performs a first phase control process (S63). The first phase control process is a process of adjusting the phase of the drive voltage V in a direction in which the phase of the current I is consistent with the phase of the induced voltage E. In other words, the first phase control process is a process of adjusting the phase of the drive voltage V based on the relationship between the phase of the current I and the rotational position information of the motor 4. Since the number of inflection points Ninfle is less than 1, the phase adjustment unit 9 can infer that the current phase of the drive voltage V is away from the optimal phase. As a result, the phase adjustment unit 9 performs a first phase control process with better responsiveness than the second phase control process. The details of the first phase control process will be described later. When the first phase control process is completed, the phase adjustment unit 9 performs the process of S65.

[0073] In contrast, when the number of inflection points Ninfle is not less than 1 (S62, No), the phase adjustment unit 9 performs a second phase control process (S64). The second phase control process is a process of adjusting the phase of the drive voltage V in a direction that decreases the index calculated based on the peak value of the current I and the rotation speed of the motor 4. In other words, the second phase control process is a process of adjusting the phase of the drive voltage V based on the magnitude of the current I and the rotation speed of the motor 4. Since the number of inflection points Ninfle is not less than 1, that is, the count increases and becomes greater than 1, the phase adjustment unit 9 can infer that the current phase of the drive voltage V is near the optimal phase. As a result, the phase adjustment unit 9 performs a second phase control process that can drive the motor more efficiently than the first phase control process. The details of the second phase control process will be described later. When the second phase control process is completed, the phase adjustment unit 9 performs the process of S65.

[0074] In the process of S65, the phase adjustment unit 9 determines whether the variable C is larger than the threshold value Cref (S65). By determining whether the variable C is larger than the threshold value Cref, it is determined whether the process of advancing the phase or the process of delaying the phase is being continuously executed.

[0075] When the variable C is greater than the threshold value Cref (S65, Yes), the phase adjustment unit 9 substitutes 0 into the number of inflection points Ninfle and substitutes 0 into the variable C (S66). Since the variable C is greater than the threshold value Cref, it is known that the process of advancing the phase or the process of delaying the phase has been continuously performed more than the threshold value Cref times. In order to avoid converging to a value other than the optimal phase, the phase adjustment unit 9 sets the number of inflection points Ninfle to 0 and initializes the variable C to 0. When the process of S66 is completed, the process of S62 is executed.

[0076] On the other hand, when the variable C is not greater than the threshold Cref (S65, No), the process of S62 is executed. When the variable C is not greater than the threshold Cref, that is, when the variable C is less than the threshold Cref, the process proceeds to the next process without changing the variable.

[0077] Thereafter, the processes of S62 to S66 are repeatedly executed while the driving operation is being executed.

[0078] Figure 7 1 is a flowchart showing a first phase control process of the driving device according to the first embodiment.

[0079] When the first phase control process starts (start), the phase adjustment unit 9 detects the slope of the current based on the output of the current value processing unit 10 (S71). Specifically, the phase adjustment unit 9 receives information on the slope of the waveform of the current I from the current value processing unit 10.

[0080] Next, the phase adjustment unit 9 determines whether the detected slope is positive ( S72 ).

[0081] When the detected slope is positive (S72, yes), the phase adjustment unit 9 performs an advance angle process (S73). The advance angle process is a process of advancing the phase of the drive voltage V and updating the number of inflection points Ninfle and / or the variable C based on the previous advance angle process or delay angle process. The details of the advance angle process will be described later. Since the detected slope is positive, it can be inferred that the phase of the current I is delayed relative to the phase of the induced voltage E. Thus, by performing the advance angle process to advance the phase of the drive voltage V, the phase of the drive voltage V can be brought close to the optimal phase. When the advance angle process is completed, the first phase control process ends (end).

[0082] In contrast, in S72, when the detected slope is not positive (S72, No), the phase adjustment unit 9 performs a delay angle process (S74). The delay angle process is a process of delaying the phase of the drive voltage V and updating the number of inflection points Ninfle and / or the variable C based on the previous advance angle process or delay angle process. The details of the delay angle process will be described later. Since the detected slope is not positive, that is, it is negative, it can be inferred that the phase of the current I is advanced relative to the phase of the induced voltage E. Thus, by performing the delay angle process to delay the phase of the drive voltage V, the phase of the drive voltage V can be made close to the optimal phase. When the delay angle process is completed, the first phase control process ends (ends).

[0083] Figure 8 1 is a flowchart showing the advance angle processing of the drive device according to the first embodiment.

[0084] When the advance angle processing starts (start), the phase adjustment unit 9 adds the phase shift amount to advance the phase of the drive voltage V (S81).

[0085] Next, the phase adjustment unit 9 substitutes 1 into the variable Pa ( S82 ).

[0086] Next, the phase adjustment unit 9 determines whether the variable Pa is equal to the variable Pb ( S83 ).

[0087] When the variable Pa is equal to the variable Pb (S83, Yes), the phase adjustment unit 9 increments the variable C by 1 (S84). That is, the count of the number of times the process of advancing the phase is continuously executed is incremented. When the process of S84 is completed, the phase adjustment unit 9 executes the process of S86.

[0088] On the other hand, when the variable Pa is not equal to the variable Pb (S84, No), that is, when the variable Pa is different from the variable Pb, the phase adjustment unit 9 increases the number of inflection points Ninfle by 1 and substitutes 0 into the variable C (S85). Since the variable Pa is different from the variable Pb, it can be known that the angle delay process was performed last time and the angle advance process was performed this time. Therefore, the number of inflection points Ninfle is counted up and the variable C is reset to 0. When the process of S85 is completed, the phase adjustment unit 9 executes the process of S86.

[0089] In the process of S86, the phase adjustment unit 9 substitutes the variable Pa into the variable Pb (S86). This process allows the process performed this time to be referred to when the advance angle process or the retard angle process is performed next time. When the process of S86 is completed, the advance angle process ends (end).

[0090] Fig. 9 1 is a flowchart showing the delay angle processing of the drive device according to the first embodiment.

[0091] When the delay angle processing starts (start), the phase adjustment unit 9 subtracts the phase shift amount to delay the phase of the drive voltage (S91).

[0092] Next, the phase adjustment unit 9 substitutes -1 into the variable Pa ( S92 ).

[0093] Next, the phase adjustment unit 9 determines whether the variable Pa is equal to the variable Pb ( S93 ).

[0094] When the variable Pa is equal to the variable Pb (S93, Yes), the phase adjustment unit 9 increments the variable C by 1 (S94). That is, the count of the number of times the phase delay process is continuously executed is incremented. When the process of S94 is completed, the phase adjustment unit 9 executes the process of S96.

[0095] On the other hand, when the variable Pa is not equal to the variable Pb (S93, No), that is, when the variable Pa is different from the variable Pb, the phase adjustment unit 9 increases the number of inflection points Ninfle by 1 and substitutes 0 into the variable C (S95). Since the variable Pa is different from the variable Pb, it can be known that the advance angle processing was performed last time and the retard angle processing was performed this time. Therefore, the number of inflection points Ninfle is counted up and the variable C is reset to 0. When the processing of S95 is completed, the phase adjustment unit 9 executes the processing of S96.

[0096] In the process of S96, the phase adjustment unit 9 substitutes the variable Pa into the variable Pb (S96). When the process of S96 is completed, the delay angle process ends (END).

[0097] Fig.10 : is a flowchart showing the second phase control process of the driving device according to the first embodiment.

[0098] When the second phase control process starts (start), the phase adjustment unit 9 obtains the peak value Ip of the current ( S101 ). Specifically, the phase adjustment unit 9 receives the peak value Ip of the current from the current value processing unit 10 .

[0099] Next, the phase adjustment unit 9 obtains the count value N ( S102 ). Specifically, the phase adjustment unit 9 receives the count value N from the rotation speed calculation unit 7 .

[0100] Next, the phase adjustment unit 9 determines whether the current I has switched to the next cycle (S103). Specifically, the phase adjustment unit 9 determines whether the current I has switched to the next cycle based on the zero crossing detection result in the rotation speed calculation unit 7. According to the result of this determination, it is determined whether to execute the processing after S104. In addition, through this determination, the processing after S104 is executed once for one cycle of the current I.

[0101] When the current I is not switched to the next cycle ( S103 , No), the second phase control process ends (END).

[0102] When the current I switches to the next cycle (S103, Yes), the phase adjustment unit 9 substitutes the calculation result into the variable ηa (S104). The variable ηa(n-1) of the n-1th cycle and the index η(n) of the nth cycle are used to express the variable ηa(n) of the nth cycle as in equation (8). That is, the value substituted into the variable ηa is the value obtained by accumulating the index η shown in equation (7) multiple times.

[0103]

Formula 8

[0104] eta(n)=eta(n-1)+eta(n)=eta(n-1)+Ip×N (8)

[0105] Next, the phase adjustment unit 9 determines at which stage the phase adjustment of the driving voltage V is in (S105). Stage includes, for example, four states: 0, 1, 2, and 3. Stage0 is a state in which the phase is advanced and then Stage1 is executed. Stage1 is selected after the phase advance process is completed in Stage0. Stage1 is a state in which a determination is made as to whether the variable ηa is smaller than the previous cumulative value or larger than the previous cumulative value, and Stage0 or Stage2 is selected in the next process based on the determination. Stage2 is a state in which the phase is delayed and then Stage3 is executed. Stage3 is selected after the phase delay process is completed in Stage2. Stage3 is a state in which a determination is made as to whether the variable ηa is smaller than the previous cumulative value or larger than the previous cumulative value, and Stage0 or Stage2 is selected in the next process based on the determination.

[0106] In S105, when Stage is 0 (S105, Stage=0), the phase adjustment unit 9 performs an advance angle process (S106a). This advance angle process is similar to the reference Figure 8 The processing described is the same. Next, the phase adjustment unit 9 sets Stage to 1 (S106b). Next, the phase adjustment unit 9 adds 1 to the variable α (S106c). When the processing of S106c is completed, the second phase control processing ends (end).

[0107] In S105, when Stage is 1 (S105, Stage = 1), the phase adjustment unit 9 determines whether the variable α is greater than or equal to the reference value αref (S107a). The reference value αref is a value that determines the number of times the index η is accumulated when the variable ηa is calculated. When the variable α is not greater than or equal to the reference value αref (S107a, No), the phase adjustment unit 9 adds 1 to the variable α (S107f). When the processing of S107f is completed, the second phase control processing ends (end).

[0108] On the other hand, in S107a, when the variable α is greater than the reference value αref (S107a, Yes), the phase adjustment unit 9 determines whether the variable ηa is smaller than the variable ηb (S107b). When the variable ηa is smaller than the variable ηb (S107b, Yes), the phase adjustment unit 9 sets Stage to 0 (S107c). That is, the phase adjustment unit 9 is set to perform the advance angle processing when the second phase control processing is performed next time and the processing after S105 is performed. When the processing of S107c is completed, the phase adjustment unit 9 performs the processing of S107e.

[0109] On the other hand, when the variable ηa is smaller than the variable ηb (S107b, No), the phase adjustment unit 9 sets Stage to 2 (S107d). That is, the phase adjustment unit 9 is set to perform the delay angle processing when the second phase control processing is performed next time and the processing after S105 is performed. When the processing of S107d is completed, the phase adjustment unit 9 performs the processing of S107e.

[0110] In the process of S107e, the phase adjustment unit 9 substitutes 0 into the variable α, substitutes the variable ηa into the variable ηb, and substitutes 0 into the variable ηa (S107e). When reviewing the process so far, in the process of S107a, it is confirmed that the variable ηa is accumulated only in a predetermined period, in S107b, the magnitude relationship between the variable ηa and the variable ηb is confirmed, and the Stage is changed by the process of S107c or S107d. Therefore, the purpose of S107e is to reset or update each variable to prepare for the next action. In S107e, the phase adjustment unit 9 resets the variable α to 0, saves the value of the variable ηa in the variable ηb, and resets the variable ηa to 0. When the process of S017e is completed, the second phase control process ends (end).

[0111] In S105, when the Stage is 2 (S105, Stage=2), the phase adjustment unit 9 performs a delay angle process (S108a). This delay angle process is similar to the reference Fig. 9 The processing described is the same. Next, the phase adjustment unit 9 sets Stage to 3 (S108b). Next, the phase adjustment unit 9 increases the variable α by 1 (S108c). When the processing of S108c is completed, the second phase control processing ends (end).

[0112] In S105, when Stage is 3 (S105, Stage=3), the phase adjustment unit 9 determines whether the variable α is greater than or equal to the reference value αref (S109a). When the variable α is not greater than or equal to the reference value αref (S109a, No), the phase adjustment unit 9 adds 1 to the variable α (S109f). When the processing of S109f is completed, the second phase control processing ends (End).

[0113] On the other hand, when the variable α is greater than the reference value αref in S109a (S109a, Yes), the phase adjustment unit 9 determines whether the variable ηa is smaller than the variable ηb (S109b). When the variable ηa is smaller than the variable ηb (S109b, Yes), the phase adjustment unit 9 sets Stage to 2 (S109c). That is, the phase adjustment unit 9 is set to perform the delay angle processing when the second phase control processing is performed next time and the processing after S105 is performed. When the processing of S109c is completed, the phase adjustment unit 9 performs the processing of S109e.

[0114] On the other hand, when the variable ηa is smaller than the variable ηb (S109b, No), the phase adjustment unit 9 sets Stage to 0 (S109d). That is, the phase adjustment unit 9 is set to perform the advance angle processing when the second phase control processing is performed next time and the processing after S105 is performed. When the processing of S109d is completed, the phase adjustment unit 9 performs the processing of S109e.

[0115] In the process of S109e, the phase adjustment unit 9 substitutes 0 into the variable α, substitutes the variable ηa into the variable ηb, and substitutes 0 into the variable ηa (S109e). When reviewing the process so far, in the process of S109a, it is confirmed that the variable ηa is accumulated only in a predetermined period, in S109b, the magnitude relationship between the variable ηa and the variable ηb is confirmed, and the Stage is changed by the process of S109c or S109d. Therefore, the purpose of S109e is to reset each variable to prepare for the next action. In S109e, the phase adjustment unit 9 resets the variable α to 0, saves the value of the variable ηa in the variable ηb, and resets the variable ηa to 0. When the process of S109e is completed, the second phase control process ends (end).

[0116] By operating the phase adjustment unit 9 in this manner, the phase of the current I can be adjusted in accordance with the method shown in Table 1.

[0117] The driving device of the first embodiment performs: a first phase control process to adjust the phase of the driving voltage V based on the relationship between the phase of the current I and the rotational position information of the motor 4; and a second phase control process to adjust the phase of the driving voltage V based on the magnitude of the current I and the rotational speed of the motor 4. The control of the first phase control process is simple, so it can be executed at a high speed and has excellent responsiveness compared to the second phase control process. The second phase control process is controlled based on the indicator η, so even an embedded magnet type motor can be driven efficiently. The driving device of the first embodiment is to combine these, approach the optimal phase at a high speed through the first phase control process, and then execute the second phase control process, thereby achieving both the responsiveness of the phase control and the efficient driving of the motor.

[0118] In addition, the driving device of the first embodiment switches the first phase control process and the second phase control process according to the number of inflection points Ninfle. Specifically, when the number of inflection points Ninfle is less than the threshold value, even if the advance angle process or the delay angle process in which the offset changes toward the vicinity of the optimal value is continuously performed, the first phase control process with excellent responsiveness of the phase control is performed. In contrast, when the number of inflection points Ninfle is greater than the threshold value, that is, when the offset reaches the vicinity of the optimal value, the second phase control process capable of efficiently driving the motor is performed. In this way, the driving device of the first embodiment can take into account both the responsiveness of the phase control and the efficient driving of the motor.

[0119] (Second Embodiment)

[0120] The driving device of the second embodiment is different from the driving device of the first embodiment in the content of the first phase control process. The following describes the differences between the driving device of the second embodiment and the first embodiment.

[0121] The principle used in the first phase control process in the driving device according to the second embodiment will be described. Fig.11 This is a waveform diagram showing an example of current detection based on a shunt resistor. Fig.11 2 shows a plurality of examples of current waveforms detected when the current detection unit 6 uses a shunt resistor. Fig.11 , three current waveforms are shown in sequence from the top in the vertical direction when the phase of the driving voltage V is advanced, when the power factor is 1, and when the phase of the driving voltage V is delayed. Fig.11 As shown in FIG. 1 , when the motor current is detected by the shunt resistor, the output voltage of the power converter 1 is phase-divided into six parts per cycle. At this time, if the phase of the drive voltage V is the same as the phase of the current I, then Fig.11 As shown in the center of the waveform, the waveform becomes a convex waveform in the center of each divided part. In addition, if the phase of the driving voltage V is the same as the phase of the current I, the operation becomes a power factor of 1. When the phase of the driving voltage V is ahead of the power factor 1, the convex position of the waveform is advanced, so as shown in FIG. Fig.11 As shown in the upper part of the waveform, it becomes a waveform shape that falls to the right. When the phase of the driving voltage V is delayed compared to the power factor 1, the position of the convex part of the waveform is delayed, so as shown in Fig.11 In the second embodiment, the first phase control process is performed by utilizing the difference in the waveform shape.

[0122] The current value processing unit 10 included in the driving device of the first embodiment is different from the current value processing unit 10 included in the driving device of the second embodiment in that it also has a function of sending the current value to the phase adjustment unit 9. Specifically, the current value processing unit 10 of the second embodiment sends the value of the current I detected by the current detection unit 6 to the phase adjustment unit 9. The other configurations of the driving device of the second embodiment and the driving system including the driving device and the motor are the same as those of the first embodiment.

[0123] Fig.12 1 is a flowchart showing a first phase control process of the driving device according to the second embodiment.

[0124] When the first phase control process starts (start), the phase adjustment unit 9 initializes variables β, Ia, Ib, and Id to 0 (S121). Variable β is a variable whose count increases when the variable Id described later is positive, and whose count decreases when the variable Id is not positive. Variable Ia is a variable that stores the current value obtained from the current value processing unit 10. Variable Ib is a variable that stores the current value obtained last time. Variable Id is a variable that stores a value obtained by subtracting variable Ib from variable Ia.

[0125] Next, the phase adjustment unit 9 obtains the current value from the current value processing unit 10 and substitutes it into the variable Ia (S122). Specifically, the phase adjustment unit 9 obtains the current value of the current I from the current value processing unit 10 and substitutes it into the variable Ia.

[0126] Next, the phase adjustment unit 9 subtracts the variable Ib from the variable Ia and substitutes the result into the variable Id (S123). The variable Ib is a variable storing the current value obtained last time. Thus, through this process, the difference between the current value obtained this time, i.e., the variable Ia, and the current value obtained last time, i.e., the variable Ib, is substituted into the variable Id.

[0127] Next, the phase adjustment unit 9 determines whether the variable Id is positive (S124). When the variable Id is positive (S124, Yes), the phase adjustment unit 9 adds 1 to the variable β (S125a). When the processing of S125a is completed, the phase adjustment unit 9 performs the processing of S126. On the other hand, in S124, when the variable Id is not positive (S124, No), the phase adjustment unit 9 subtracts 1 from the variable β (S125b). When the processing of S125b is completed, the phase adjustment unit 9 performs the processing of S126.

[0128] In S126, the phase adjustment unit 9 substitutes the value of the variable Ia into the variable Ib (S126). Through this process, the current value obtained this time is substituted into the variable Ib, and is used as the current value obtained last time in the next process.

[0129] Next, the phase adjustment unit 9 determines whether the current I has switched to the next cycle (S127). If the cycle has not switched (S127, No), the process of S122 is executed. That is, the processes of S122 to S126 are repeatedly executed until the cycle switches.

[0130] On the other hand, in S127, when the cycle is switched (S127, yes), the phase adjustment unit 9 determines whether the variable β is positive (S128). The variable β is counted up when the variable Id is positive and counted down when the variable Id is negative through the processing of S124, S125a and S125b. Then, these processes are repeated until the cycle of the current is switched through the processing of S127. As a result, in the variable β, the positive or negative number determines whether the variable Id is more positive or more negative. The variable Id is the difference between the current value this time and the previous current value, so the case where the variable β is positive means that the current I is on an increasing trend. The case where the variable β is not positive means that the current I is on a decreasing trend. As shown in FIG. Fig.11 As described above, when the phase of the driving voltage V is delayed, the current waveform becomes a shape that rises to the right, and when the phase of the driving voltage V is advanced, the current waveform becomes a shape that falls to the right. Thus, the phase adjustment unit 9 can infer the phase delay of the driving voltage V when the variable β is positive, and infer the phase advance of the driving voltage V when the variable β is not positive.

[0131] In S128, when the variable β is positive (S128, Yes), the phase adjustment unit 9 performs an advance angle process (S129a). Figure 8 The processing described is the same. The phase delay of the drive voltage V is inferred from the case where the variable β is positive. Thus, the phase of the drive voltage V is advanced by performing the advance angle processing, thereby enabling the phase of the drive voltage V to approach the optimal phase. When the processing of S129a is completed, the first phase control processing ends (end).

[0132] In S128, when the variable β is not positive (S128, No), the phase adjustment unit 9 performs a delay angle process (S129b). Fig. 9 The processing described is the same. The phase of the drive voltage V is inferred to be advanced from the fact that the variable β is not positive. Thus, the phase of the drive voltage V is delayed by performing the delay angle processing, thereby enabling the phase of the drive voltage V to approach the optimal phase. When the processing of S129b is completed, the first phase control processing ends (end).

[0133] In this way, the first phase control process can also be implemented based on the waveform shape of the current I.

[0134] Furthermore, even when the first phase control process is implemented in this way, the driving device of the second embodiment can achieve both responsiveness and efficient driving, similarly to the first embodiment.

[0135] (Variation examples, etc.)

[0136] In the above-mentioned embodiment, the case where the rotor position detection unit 5 includes a rotary encoder or a Hall sensor installed on the motor 4 is used as an example for explanation. The rotor position detection unit 5 may also adopt a so-called sensorless method in which no sensor is provided. For example, in one example, the rotor position detection unit 5 directly detects the induced voltage E of the motor 4, and detects the position of the rotor based on the phase of the induced voltage E, etc. In addition, in another example, the rotor position detection unit 5 obtains information related to the current I flowing in the motor 4 from the current detection unit 6. Then, the rotor position detection unit 5 uses the operating state of the motor 4 such as the current I and a fixed constant to infer the position of the rotor. In addition, when the rotor position detection unit 5 adopts a sensorless method, the rotor position detection unit 5 may also be installed on the integrated circuit 12 together with the rotation speed calculation unit 7, the voltage control unit 8, the phase adjustment unit 9, and the current value processing unit 10.

[0137] In the above embodiment, the current detection unit 6 is described as a so-called one-shunt method in which a shunt resistor is arranged at one position of the power line on the negative side (ground side) of the power converter 1. The current detection unit 6 may also adopt a three-shunt method in which shunt resistors are arranged at three positions in the power converter 1 by arranging shunt resistors between the emitters of the three IGBTs 2 on the negative side (ground side) and the power line on the negative side.

[0138] Several embodiments of the present invention have been described, but these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and their variations are included in the scope and purpose of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A driving device comprising: A power converter converts the input power into AC power and supplies it to the motor; a voltage control unit that controls the operation of the power converter to apply a driving voltage from the power converter to the motor; as well as a phase adjustment unit that performs a first process of advancing the phase of the driving voltage and a second process of delaying the phase of the driving voltage to adjust the phase of the driving voltage; The phase adjustment unit performs: a first phase control process of receiving first information related to a relationship between a phase of a current flowing in the motor and a rotational position of the motor, and adjusting a phase of the drive voltage based on the first information; as well as The second phase control process receives second information related to the magnitude of the current flowing through the motor and third information related to the rotation speed of the motor, and adjusts the phase of the drive voltage based on the second information and the third information.

2. The driving device according to claim 1, wherein: The phase adjustment unit performs the first phase control process or the second phase control process based on a first number of times that the second process is performed following the first process or the first process is performed following the second process.

3. The driving device according to claim 2, wherein: The phase adjustment unit performs the first phase control process when the first number of times is less than a first threshold value, and performs the second phase control process when the first number of times is greater than or equal to the first threshold value.

4. The driving device according to claim 2, wherein: The phase adjustment unit resets the first number of times when the first process is continuously executed more than a second threshold value or when the second process is continuously executed more than the second threshold value.

5. The driving device according to claim 1, wherein: The phase adjustment unit controls the phase of the drive voltage in the first phase control process so that the phase of the current flowing through the motor matches the phase of the induced voltage detected based on the rotational position of the motor.

6. The driving device according to claim 1, wherein: The second information includes information related to a peak value of a current flowing through the motor in one cycle of alternating current, and the third information includes information related to an inverse number of a rotation speed of the motor.

7. The driving device according to claim 6, wherein: The phase adjustment unit controls the phase of the drive voltage in the second phase control process so that the product of the peak value and the inverse of the rotation speed becomes small.

8. A method for controlling a motor, comprising: Converting the input power into AC power by means of a power converter, and supplying the converted AC power to the motor; detecting a current flowing in the motor, a rotational position of the motor, and a rotational speed of the motor; Based on the detected current and the rotational position, a first process of advancing the phase of a drive voltage applied from the power converter to the motor and a second process of delaying the phase of the drive voltage are performed to adjust the phase of the drive voltage; as well as When the second process is executed after the first process or the first process is executed after the second process a number of times equal to or greater than a first threshold, the first process and the second process are executed based on the detected current and the rotation speed to adjust the phase of the drive voltage.

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