Motor control device and motor control method

Abstract

To provide a motor control device which can calculate a rotor position and rotational speed of a motor with high accuracy in a short time.SOLUTION: A motor control device 4 according to the present invention comprises a speed / phase estimation unit 13 which estimates a rotor position and speed of a motor 3 by using a rotor position and speed calculated by an idling state estimation unit 14. The idling state estimation unit 14 comprises: a first current phase calculation unit 18 which calculates a first phase θi1 as a phase of current Iαβ flowing to the motor 3 in an idling state; a DC component calculation unit 23 which calculates DC current Iα_DC flowing to the motor 3 in the idling state by using current Iαβ when size of the first phase θi1 is the maximum and the first phase θi1 ; a second current phase calculation unit 25 which calculates a second phase θi2 as a phase of current Ie generated by idling of the motor 3 by using the DC current Iα_DC and the current Iαβ; and idling speed / phase estimation units 26, 27 which calculate the rotor position and the speed of the motor 3 in the idling state by using the second phase θi2.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an apparatus and method for controlling the operation of a motor. [Background technology]

[0002] In the fields of home appliances and industrial equipment, motor drive systems consisting of an inverter that converts DC power to AC power and a permanent magnet synchronous motor are widely used. In order to drive such a permanent magnet synchronous motor with high efficiency, information about the rotor position of the motor is generally required. The rotor position of the motor can be directly detected by using a position detector such as an encoder, but this method has problems in terms of cost and reliability. Therefore, in recent years, position sensorless control that detects the rotor position of a permanent magnet synchronous motor without using a position detector has been proposed and is applied to various products.

[0003] One of the issues with position sensorless control of permanent magnet synchronous motors is the method of restarting the motor when the rotor is free-spinning (known as "coast-run start"). For example, the motor of a washing machine or the like may already be rotating, i.e., free-spinning, before starting due to the inertia of the load. In this case, if there is no information on the rotor position, rotation speed, and rotation direction in the free-spinning state, it is necessary to wait until the motor stops, or to forcibly stop the motor rotation by applying brake control and restart the stopped motor. This poses the issue of the time required for restart being long.

[0004] In response to this, for example, technologies have been developed that focus on the induced voltage that occurs when a permanent magnet synchronous motor spins by shorting the motor windings using an inverter, as in the motor control devices described in Patent Documents 1 and 2, in which the rotor position, etc. are estimated based on the current that flows at this time.

[0005] In the motor control device described in Patent Document 1, of the switching elements that make up the motor drive inverter, three upper (or lower) arm elements are turned on simultaneously to pass a short-circuit current through the motor windings, and the rotor position and rotation speed are calculated based on the detection information of the three-phase motor current.

[0006] In the motor control device described in Patent Document 2, elements of different arms for two phases of a motor drive inverter are turned on and off simultaneously, the bus current on the DC side of the inverter is detected by a shunt resistor, and the motor rotor position and rotational speed are calculated. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2015-73361 A [Patent Document 2] JP 2018-170928 A Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional techniques, such as the motor control devices described in Patent Documents 1 and 2, have the following problems.

[0009] In the motor control device described in Patent Document 1, the short-circuit current flowing through the motor windings during short-circuit operation of the inverter is determined by the induced voltage of the motor and the resistance and inductance of the windings, so depending on the idling speed, an overcurrent may occur during short-circuit operation. The occurrence of an overcurrent has an undesirable effect on the motor.

[0010] The motor control device described in Patent Document 2 uses a special PWM control mode and current detection processing by detecting the bus current flowing through a shunt resistor, which complicates the calculations for calculating the motor rotor position and rotational speed, making it prone to errors in the estimation results.

[0011] The present invention has been made in consideration of the above-mentioned problems with the conventional technology, and an object of the present invention is to provide a motor control device and a motor control method that can calculate the rotor position and rotational speed of a motor with higher accuracy and in a shorter time. [Means for solving the problem]

[0012] A motor control device according to the present invention is configured to control the operation of a permanent magnet synchronous motor by controlling an inverter that supplies AC power to the permanent magnet synchronous motor, and includes a voltage command generating unit that outputs a voltage command to pass a DC current through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in an idling state, an idling state estimating unit that calculates a rotor position and rotation speed of the permanent magnet synchronous motor in the idling state, and a speed / phase estimating unit that estimates the rotor position and rotation speed of the permanent magnet synchronous motor using the rotor position and rotation speed calculated by the idling state estimating unit as initial values. A current obtained by adding a current generated by idling of the permanent magnet synchronous motor to the DC current flows through the permanent magnet synchronous motor in the idling state. The idling state estimation unit includes a first current phase calculation unit that calculates a first current phase, which is the phase of a current flowing through the permanent magnet synchronous motor in the idling state, a DC component calculation unit that calculates the DC current using the magnitude of the current and the magnitude of the first current phase when the magnitude of the first current phase is maximum, a second current phase calculation unit that calculates a second current phase, which is the phase of a current generated due to idling of the permanent magnet synchronous motor, using the DC current and the current, and an idling speed / phase estimation unit that calculates a rotor position and a rotational speed of the permanent magnet synchronous motor in the idling state using the second current phase.

[0013] A motor control method according to the present invention is a motor control method for controlling the operation of a permanent magnet synchronous motor by controlling an inverter that supplies AC power to the permanent magnet synchronous motor, and includes a voltage command generating step of outputting a voltage command to pass a DC current through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in an idling state, an idling state estimating step of calculating a rotor position and rotation speed of the permanent magnet synchronous motor in the idling state, and a speed / phase estimating step of estimating the rotor position and rotation speed of the permanent magnet synchronous motor using the rotor position and rotation speed calculated in the idling state estimating step as initial values. A current obtained by adding a current generated by idling of the permanent magnet synchronous motor to a DC current flows through the permanent magnet synchronous motor in the idling state. The idling state estimation process includes a first current phase calculation process of calculating a first current phase which is the phase of a current flowing through the permanent magnet synchronous motor in an idling state; a DC component calculation process of calculating a DC current using the magnitude of the current when the magnitude of the first current phase is maximum and the magnitude of the first current phase; a second current phase calculation process of calculating a second current phase which is the phase of a current generated by the idling of the permanent magnet synchronous motor using the DC current and the current; and an idling speed / phase estimation process of calculating a rotor position and a rotational speed of the permanent magnet synchronous motor in an idling state using the second current phase. Effect of the Invention

[0014] According to the present invention, it is possible to provide a motor control device and a motor control method that are capable of calculating the rotor position and rotational speed of a motor with higher accuracy and in a shorter time. [Brief description of the drawings]

[0015] [Figure 1] 1 is a diagram illustrating an overall configuration of a motor control system including a motor control device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a functional block diagram showing the processing contents of the motor control device. [Figure 3A] 3 is an explanatory diagram showing current vectors when a direct current flows through a permanent magnet synchronous motor; FIG. [Figure 3B] FIG. 13 is a diagram showing a current value iα_0 calculated by a calculation unit. [Figure 4] FIG. 4 is a functional block diagram showing the processing contents of a spin state estimation unit. [Diagram 5] 1 is a vector diagram showing an induced voltage E generated in a permanent magnet synchronous motor in an idling state and a current Ie generated under the influence of the induced voltage E. [Figure 6A] FIG. 1 is an explanatory diagram showing a current vector when the magnitude of the first current phase θi1 is maximum when a DC current is passed through a permanent magnet synchronous motor, and shows a current vector whose absolute value |θi1| is maximum when the β-axis current iβ is positive. [Figure 6B] FIG. 1 is an explanatory diagram showing a current vector when the magnitude of the first current phase θi1 is maximum when a DC current is passed through a permanent magnet synchronous motor, and shows a current vector whose absolute value |θi1| is maximum when the β-axis current iβ is negative. [Figure 7] 13 is an example of a flowchart illustrating a processing procedure for setting a maximum value detection flag F_theta_max. [Figure 8] 13 is an example of a flowchart showing a processing procedure for calculating a direct current Iα_DC. [Figure 9] 1 is a diagram showing time series changes in each parameter calculated by the motor control device according to the present embodiment and the phase θd of the induced voltage of the permanent magnet synchronous motor. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] The motor control device according to this embodiment includes an idling state estimation unit, calculates the phase of the current (second current phase θi2) generated by idling of the motor, and calculates the rotor position and rotation speed of the motor in an idling state using this phase. With this configuration, the motor control device according to this embodiment calculates the rotor position and rotation speed of the motor with simple calculations that cause little error without using a position detector, so that the rotor position and rotation speed of the motor can be calculated with higher accuracy and in a shorter time.

[0017] Hereinafter, a motor control device and a motor control method according to an embodiment of the present invention will be described with reference to the drawings. In the following embodiment, as an example, a control target of the motor control device will be described as a permanent magnet synchronous motor (PMSM). EXAMPLES

[0018] FIG. 1 is a diagram showing a schematic diagram of the overall configuration of a motor control system including a motor control device according to the present embodiment.

[0019] The motor control system shown in FIG. 1 includes, as main components, a motor control device 4 according to this embodiment, a permanent magnet synchronous motor 3, a DC power supply 1, and an inverter 2.

[0020] The motor control device 4 generates a control signal for the inverter 2 to control the inverter 2, thereby controlling the operation of the permanent magnet synchronous motor 3. The motor control device 4 can be configured with a semiconductor arithmetic device such as a microcomputer or a DSP (digital signal processor), for example.

[0021] The permanent magnet synchronous motor 3 includes a rotor incorporating a permanent magnet, and is controlled by a motor control device 4 via an inverter 2. The permanent magnet synchronous motor 3 is a motor having multiple phases. In this embodiment, as an example, the permanent magnet synchronous motor 3 is a three-phase motor.

[0022] The DC power supply 1 can be configured by any device. For example, the DC power supply 1 can be a power conversion device (e.g., a diode rectifier or a stabilized power supply) that converts AC power received from an AC power supply such as a commercial AC power supply (not shown) into DC power, or a battery.

[0023] In this embodiment, the inverter 2 performs PWM (Pulse Width Modulation) control to control the operation of the permanent magnet synchronous motor 3. The inverter 2 converts DC power from the DC power supply 1 into AC power, and supplies the AC power to the permanent magnet synchronous motor 3.

[0024] The inverter 2 includes a plurality of series-connected circuits each configured by connecting two arm circuits, in other words an upper arm and a lower arm, in series with each other. Each arm circuit (upper arm and lower arm) is configured by connecting a semiconductor switching element (IGBT, MOSFET, etc.) and a diode in anti-parallel. The plurality of series-connected circuits are connected between a pair of positive and negative terminals of the DC power source 1.

[0025] The inverter 2 includes series-connected circuits equal in number to the phases of the AC to be output. For example, in this embodiment, the inverter 2 is a three-phase inverter including three (i.e., three) series-connected circuits for three phases. The upper arm of the inverter 2 is connected to the high potential side of the DC power supply 1, and the lower arm is connected to the low potential side of the DC power supply 1. The connection point where the upper arm and the lower arm are connected to each other in series is connected to an AC terminal. A permanent magnet synchronous motor 3 is connected to this AC terminal.

[0026] The low-potential busbar of the inverter 2 is connected to the negative terminal of the DC power supply 1 via a shunt resistor 5 for current detection. A current detection signal detected by the shunt resistor 5 is input to the motor control device 4 via an amplifier 6. A signal output from the amplifier 6 to the motor control device 4 is converted to a digital signal by a sample-and-hold circuit and an A / D converter (not shown) for digital calculation in the motor control device 4. In other words, the shunt resistor 5 and the amplifier 6 constitute a DC current detector that detects a DC current flowing through the low-potential busbar of the inverter 2 and outputs a current detection signal to the motor control device 4. Note that instead of the shunt resistor 5, another current detection device such as a current sensor may be used.

[0027] The high potential side busbar of the inverter 2 is connected to the positive terminal of the DC power supply 1. Between the high potential side busbar and the low potential side busbar of the inverter 2, a DC voltage detector 50 is installed which detects the DC voltage between the high potential side busbar and the low potential side busbar and outputs a DC voltage detection signal to the motor control device 4. The signal output from the DC voltage detector 50 to the motor control device 4 is converted into a digital signal, similar to the signal output from the DC current detector to the motor control device 4.

[0028] As described later, the motor control device 4 according to this embodiment executes position sensorless control, that is, control for detecting the rotor position of the permanent magnet synchronous motor 3 and performing synchronization without using a position detector. Therefore, the permanent magnet synchronous motor 3 does not include a magnetic pole position detector such as a Hall element for detecting the position of the rotor or rotating shaft.

[0029] 2 is a functional block diagram showing the processing contents of the motor control device 4. As described above, the motor control device 4 can be configured with a semiconductor arithmetic device such as a microcomputer or a DSP, and realizes each function by executing a predetermined program.

[0030] In order to avoid the effects of disturbances and noise, the motor control device 4 may perform moving average processing or low-pass filtering on values ​​used in various calculations.

[0031] 2, the motor control device 4 includes, as functional blocks, a speed control unit 7, a d-axis current command generation unit 8, a current control unit 9, a voltage command switching unit 10, a two-phase / three-phase conversion unit 11, a speed / phase estimator 13, a voltage command generation unit 12, a slip state estimator 14, a three-phase / two-phase conversion unit 15, a current reproduction calculation unit 16, a control signal generation unit 17, and a calculation unit 35. Furthermore, the motor control device 4 includes a storage unit (not shown) that can store input data and values ​​obtained by calculation.

[0032] The motor control device 4 calculates a voltage command to be applied to the permanent magnet synchronous motor 3 by vector control using the dq axes, and generates a control signal for the inverter 2 based on this voltage command (for example, a PWM (Pulse Width Modulation) control signal), thereby controlling the operation of the permanent magnet synchronous motor 3. The motor control device 4 performs operation control (normal operation control) in a normal operation state of the permanent magnet synchronous motor 3, and transition control (startup control) from an idling state in which the rotor of the permanent magnet synchronous motor 3 is idling to a normal operation state.

[0033] The normal operation control and the startup control from an idling state that are performed by the motor control device 4 on the permanent magnet synchronous motor 3 will be described below.

[0034] <Normal operation control> First, the operation of each functional block during operation control in a normal operation state (normal operation control) will be described.

[0035] The current reproduction calculation unit 16 reproduces the three-phase motor currents iu, iv, iw flowing from the inverter 2 to the permanent magnet synchronous motor 3, using the current detection signal ish output from the amplifier 6 constituting the DC current detector and the three-phase voltage commands Vu*, Vv*, Vw* output from the two-phase / three-phase conversion unit 11 to the control signal generation unit 17. The current reproduction calculation unit 16 can reproduce the three-phase motor currents iu, iv, iw from the current detection signal ish (i.e., the current detection signal detected by the shunt resistor 5) using a known method. The current reproduction calculation unit 16 outputs the reproduced three-phase motor currents iu, iv, iw to the three-phase / two-phase conversion unit 15.

[0036] In this embodiment, in order to reduce costs, a method is adopted in which the current reproduction calculation unit 16 reproduces the three-phase motor currents iu, iv, iw from the current detection signal ish detected by the shunt resistor 5 and outputs this three-phase motor current to the three-phase / two-phase conversion unit 15, but the motor control device 4 does not have to adopt this method. For example, instead of the shunt resistor 5, a current detection means such as a current sensor may be used to detect the AC current that is the output of the inverter 2, and the three-phase motor currents iu, iv, iw detected by the current detection means may be input to the three-phase / two-phase conversion unit 15.

[0037] The three-phase / two-phase conversion unit 15 performs three-phase / two-phase conversion and converts the three-phase motor currents iu, iv, and iw reproduced by the current reproduction calculation unit 16 into an α-axis current iα, which is a current in the α-axis direction, and a β-axis current iβ, which is a current in the β-axis direction. Specifically, the three-phase / two-phase conversion unit 15 calculates the α-axis current iα, the β-axis current iβ, the dc-axis current idc, and the qc-axis current iqc based on the three-phase motor currents iu, iv, and iw reproduced by the current reproduction calculation unit 16 and the phase information θd_est estimated by the speed / phase estimation unit 13, according to the following formulas (1) and (2). The α-axis current iα, the β-axis current iβ, the dc-axis current idc, and the qc-axis current iqc are the motor current in the α-axis direction, the motor current in the β-axis direction, the motor current in the dc-axis direction, and the motor current in the qc-axis direction, respectively.

[0038]

number

[0039]

number

[0040] Equation (1) represents the so-called three-phase / two-phase transformation. Equation (2) represents the transformation to a rotating coordinate system.

[0041] The dc-qc axes are estimated axes (axes of a virtual coordinate system) of a vector control system based on estimated position information, and the dq axes are motor rotor axes (axes of a coordinate system provided on the rotor). In this embodiment, the axis error (phase shift) between the dq axes and the dc-qc axes is Δθc.

[0042] The speed / phase estimation unit 13 estimates the rotor position and rotation speed of the permanent magnet synchronous motor 3 using the dc-axis current idc, the qc-axis current iqc, the dc-axis voltage command Vdc*, and the qc-axis voltage command Vqc*, and outputs them as phase information θd_est and estimated speed ωest, respectively. The speed / phase estimation unit 13 can estimate the phase information θd_est and the estimated speed ωest (i.e., the rotor position and rotation speed) using a known method.

[0043] A calculation unit 35 calculates the deviation (difference) between the speed command ω* and the estimated speed ωest estimated by the speed / phase estimation unit 13. The speed command ω* is generated by the motor control device 4 in a functional unit (not shown) in response to an external command.

[0044] The speed control unit 7 generates a qc-axis current command iqc* so that the deviation (the difference between the speed command ω* and the estimated speed ωest) calculated by the calculation unit 35 approaches 0 (zero), that is, so that the estimated speed ωest approaches the speed command ω*.

[0045] A d-axis current command generating unit 8 generates a dc-axis current command idc* for minimizing the three-phase motor currents iu, iv, and iw using a known method.

[0046] The current control unit 9 calculates and outputs a dc-axis voltage command Vdc* and a qc-axis voltage command Vqc* using the dc-axis current command idc* given from the d-axis current command generating unit 8, the qc-axis current command iqc* given from the speed control unit 7, the dc-axis current detection value idc and the qc-axis current detection value iqc given from the three-phase / two-phase conversion unit 15, the speed command ω*, and a motor constant (for example, a torque constant and a back electromotive force constant). The current control unit 9 calculates the dc-axis voltage command Vdc* and the qc-axis voltage command Vqc* using a known method.

[0047] Although not shown in the figure, the motor control device 4 includes a functional unit that determines whether the permanent magnet synchronous motor 3 is in a normal operating state or an idling state based on the rotation speed of the rotor, etc. This component outputs the result of this determination to the voltage command switching unit 10 as a control switching signal.

[0048] Depending on whether the operation state is normal or idling based on the control switching signal, the voltage command switching unit 10 outputs either the voltage commands Vdc*, Vqc* of the dc-qc axes calculated by the current control unit 9 or the voltage commands Vα*, Vβ* of the α-β axes output by the voltage command generating unit 12 to the two-phase / three-phase conversion unit 11. The voltage command generating unit 12 will be described later.

[0049] Specifically, in the normal operating state, the voltage command switching unit 10 sets the switching signal SW_signal to ON (SW_signal=1) and outputs the dc-qc axis voltage commands Vdc*, Vqc* calculated by the current control unit 9 to the two-phase / three-phase conversion unit 11. In addition, in the idling state (i.e., when startup control is being performed), the voltage command switching unit 10 sets the switching signal SW_signal to OFF (SW_signal=0) and outputs the α-β axis voltage commands Vα*, Vβ* output by the voltage command generation unit 12 to the two-phase / three-phase conversion unit 11.

[0050] In a normal operating state, the two-phase / three-phase conversion unit 11 calculates and outputs three-phase voltage commands Vu*, Vv*, Vw* according to the following equations (3) and (4) using the dc-qc axis voltage commands Vdc*, Vqc* calculated by the current control unit 9 and input via the voltage command switching unit 10, and the phase information θd_est input from the speed / phase estimation unit 13. In an idling state, the two-phase / three-phase conversion unit 11 calculates and outputs three-phase voltage commands Vu*, Vv*, Vw* according to equation (4) using the α-β axis voltage commands Vα*, Vβ* output from the voltage command generation unit 12 and input via the voltage command switching unit 10.

[0051]

number

[0052]

number

[0053] Equation (3) represents the transformation from the rotating coordinate system to the fixed coordinate system, and equation (4) represents the so-called two-phase / three-phase transformation.

[0054] The control signal generating unit 17 generates a control signal for the inverter 2 based on the three-phase voltage commands Vu*, Vv*, Vw* from the two-phase / three-phase converting unit 11 and a DC voltage detection signal from a DC voltage detector 50 (FIG. 1), and outputs this control signal to the inverter 2. The control signal generating unit 17 is, for example, a PWM controller, and generates the control signal for the inverter 2 using a known method.

[0055] <Start control from idling state> Next, the operation of each functional block in the transition control (start-up control) from the idling state to the normal operation state will be described. In the explanation of the start-up control, the differences from the normal operation control will be mainly explained, and the explanation of the control common to the normal operation control will be omitted.

[0056] First, a description will be given of the basic principle of phase detection (estimation of rotor position and rotation speed) during idling of the permanent magnet synchronous motor 3. In the following, it is assumed that the permanent magnet synchronous motor 3 is in an idling state.

[0057] When attempting to restart the permanent magnet synchronous motor 3 from an idling state without using information on the rotor position and rotation speed, it may be difficult to start the permanent magnet synchronous motor 3 using normal operation control, depending on the rotation speed of the permanent magnet synchronous motor 3. Therefore, in this embodiment, when the permanent magnet synchronous motor 3 is in an idling state, the rotor position and rotation speed of the permanent magnet synchronous motor 3 are calculated and used for start-up control.

[0058] Fig. 3A is an explanatory diagram showing current vectors when a DC current flows through the permanent magnet synchronous motor 3. In Fig. 3A, when the permanent magnet synchronous motor 3 is not rotating idly, when a DC voltage based on the α-axis is applied, a DC current Iα_DC flows on the α-axis in the permanent magnet synchronous motor 3. In this case, the β-axis current iβ becomes 0 (zero).

[0059] On the other hand, when the permanent magnet synchronous motor 3 is rotating freely (in an idling state), an induced voltage E is generated by the idling of the permanent magnet synchronous motor 3, and a current Ie generated by the influence of this induced voltage E is added to the DC current Iα_DC. Therefore, in the permanent magnet synchronous motor 3 in an idling state, a current Iαβ (=Iα_DC+Ie) flows, which is the DC current Iα_DC plus the current Ie generated by the induced voltage E as a vector.

[0060] The α-axis current iα is the current in the α-axis direction of the current Iαβ flowing through the permanent magnet synchronous motor 3. The β-axis current iβ is the current in the β-axis direction of the current Iαβ flowing through the permanent magnet synchronous motor 3. The current Ie is a current generated by the idling of the permanent magnet synchronous motor 3.

[0061] The phase angle θi1 of the current Iαβ changes according to the rotor position and rotational speed in the idling state of the permanent magnet synchronous motor 3 (i.e., according to the change in the current Ie as shown in FIG. 3A). Therefore, in this embodiment, the rotor position and rotational speed in the idling state of the permanent magnet synchronous motor 3 are estimated by utilizing the fact that the currents iα and iβ flowing through the permanent magnet synchronous motor 3 change in the idling state. Hereinafter, the angle formed by the current Iαβ and the α-axis is referred to as the first current phase θi1. The first current phase θi1 is the phase of the current Iαβ flowing through the permanent magnet synchronous motor 3.

[0062] 2 generates voltage commands Vα*, Vβ* of the α-β axes required to estimate the rotor position and rotational speed in an idling state of the permanent magnet synchronous motor 3. Then, the voltage command generating unit 12 outputs the generated voltage commands Vα*, Vβ* to the voltage command switching unit 10, thereby outputting the voltage commands Vα*, Vβ* to the two-phase / three-phase conversion unit 11 and causing a DC current Iα_DC to flow through the permanent magnet synchronous motor 3.

[0063] In this embodiment, the voltage command generating unit 12 outputs a voltage command to flow a DC current Iα_DC to one phase (in this embodiment, the phase corresponding to the α-axis) among multiple phases (in this embodiment, three phases) of the permanent magnet synchronous motor 3.

[0064] The α-axis voltage command Vα* can be set to any predetermined value. For example, the α-axis voltage command Vα* can be set by calculating or experimenting to obtain a value that can estimate the maximum speed of the permanent magnet synchronous motor 3 expected in an idling state (for example, the speed expected when the permanent magnet synchronous motor 3 is operating at a low speed). The β-axis voltage command Vβ* is set to, for example, 0 (zero).

[0065] A DC current Iα_DC flows on the α-axis due to the α-axis voltage command Vα* output by the voltage command generating unit 12 to the two-phase / three-phase converting unit 11. The DC current Iα_DC may change over time, and an initial value in the case where it changes over time can be determined arbitrarily in advance.

[0066] Next, the spin state estimating unit 14 shown in FIG. 2 will be described.

[0067] FIG. 4 is a functional block diagram showing the processing contents of the spin state estimation unit 14. As shown in FIG.

[0068] The idling state estimation unit 14 calculates an estimated initial phase θd0 as a rotor position and an estimated initial speed ωe0 as a rotation speed in an idling state of the permanent magnet synchronous motor 3, and outputs them to the speed / phase estimation unit 13 (FIG. 2). The idling state estimation unit 14 includes a first current phase calculation unit 18, an absolute value calculation unit 19, a current amplitude calculation unit 20, a maximum value detection unit 21, a cosine component calculation unit 22, a DC component calculation unit 23, a calculation unit 24, a second current phase calculation unit 25, an idling speed estimation unit 26, and an idling phase estimation unit 27. The idling speed estimation unit 26 and the idling phase estimation unit 27 are sometimes collectively referred to as an idling speed / phase estimation unit.

[0069] The calculation unit 24 calculates a current value iα_0 by subtracting the DC current Iα_DC from the α-axis current iα (for example, iα_0=iα-Iα_DC) using the α-axis current iα calculated by the 3-phase / 2-phase conversion unit 15 (FIG. 2) and the DC current Iα_DC calculated by the DC component calculation unit 23. Then, the calculation unit 24 outputs the calculated current value iα_0 to the second current phase calculation unit 25.

[0070] This current value iα_0 is a current obtained by excluding the influence of the applied DC current Iα_DC from the α-axis current iα, and can be obtained, for example, by subtracting the DC current Iα_DC from the α-axis current iα. In other words, the calculation unit 24 obtains a current obtained by excluding the contribution of the DC current Iα_DC from the current Iαβ flowing through the permanent magnet synchronous motor 3.

[0071] FIG. 3B is a diagram showing a current value iα_0 calculated by the calculation unit 24. The current value iα_0 is a value obtained by subtracting the DC current Iα_DC from the α-axis current iα (FIG. 3A). As shown in FIG. 3B, the current value iα_0 calculated by the calculation unit 24 is the α-axis component of the current Ie generated under the influence of the induced voltage E. Hereinafter, the angle between the current Ie and the α-axis is referred to as the second current phase θi2. The second current phase θi2 is the phase of the current Ie generated under the influence of the induced voltage E. The current Ie rotates around the origin of the α-β axis due to the idling of the permanent magnet synchronous motor 3.

[0072] The second current phase calculation unit 25 calculates the second current phase θi2 according to the following equation (5) using the current value iα_0 calculated by the calculation unit 24 and the β-axis current iβ calculated by the three-phase / two-phase conversion unit 15, and outputs the second current phase θi2 to the idling speed estimation unit 26 and the idling phase estimation unit 27.

[0073]

number

[0074] As described above, the second current phase θi2 is the angle between the current Ie generated by the induced voltage E and the α axis (FIGS. 3A and 3B).

[0075] The idling speed estimation unit 26 is an idling speed / phase estimation unit that calculates an estimated initial speed ωe0 by using the second current phase θi2 calculated by the second current phase calculation unit 25, and outputs the calculated estimated initial speed ωe0 to the speed / phase estimation unit 13 (FIG. 2) and the idling phase estimation unit 27.

[0076] A specific example of a method in which the idling speed estimation unit 26 calculates the estimated initial speed ωe0 will be described. The second current phase calculation unit 25 repeatedly calculates the second current phase θi2 at a predetermined control period. The idling speed estimation unit 26 calculates the difference Δθi2 (=θi2_2-θi2_1) between the value of the second current phase θi2 calculated at time t1 (previous value θi2_1) and the value of the second current phase θi2 calculated at time t2 after time t1 (present value θi2_2), and calculates the time Δt (=t2-t1) from time t1 to time t2, and calculates the estimated initial speed ωe0 (=Δθi2 / Δt) by dividing Δθi2 by the time Δt.

[0077] The idling phase estimation unit 27 is a idling speed / phase estimation unit, which calculates an estimated initial phase θd0 by the following equations (6) and (7) using the second current phase θi2 calculated by the second current phase calculation unit 25 and the estimated initial speed ωe0 calculated by the idling speed estimation unit 26, and outputs the calculated estimated initial phase θd0 to the speed / phase estimation unit 13 (FIG. 2).

[0078]

number

[0079]

number

[0080] In equation (6), Δθi is the phase difference between the second current phase θi2 and the phase of the induced voltage E, L is the inductance of the windings of the permanent magnet synchronous motor 3, and R is the resistance value of the windings of the permanent magnet synchronous motor 3.

[0081] FIG. 5 is a vector diagram showing the induced voltage E generated in the idling state of a permanent magnet synchronous motor and the current Ie generated under the influence of the induced voltage E.

[0082] As described above, Δθi is the phase difference between the second current phase θi2 and the phase of the induced voltage E. Therefore, as can be seen from FIG. 5, the estimated initial phase θd0 calculated by the equation (7) is the phase of the induced voltage E.

[0083] 2 sets the estimated initial phase θd0 calculated by the idling phase estimation unit 27 and the estimated initial speed ωe0 calculated by the idling speed estimation unit 26 as the initial values ​​of the rotor position and rotation speed when the permanent magnet synchronous motor 3 transitions from an idling state to a normal operation state (i.e., when restarting from an idling state).The speed / phase estimation unit 13 uses these initial values ​​and a known method to estimate the rotor position and rotation speed of the permanent magnet synchronous motor 3 (i.e., phase information θd_est and estimated speed ωest).

[0084] Returning to the explanation of Figure 4.

[0085] The first current phase calculation unit 18 calculates the first current phase θi1 by the following equation (8) using the α-axis current iα and β-axis current iβ calculated by the three-phase / two-phase conversion unit 15 (FIG. 2), and outputs the calculated first current phase θi1 to the absolute value calculation unit 19. As shown in FIG. 3A, this first current phase θi1 is the angle between the current Iαβ flowing through the permanent magnet synchronous motor 3 and the α-axis, and is the phase of the current Iαβ.

[0086]

number

[0087] The absolute value calculation unit 19 determines the magnitude (absolute value |θi1|) of the first current phase θi1 calculated by the first current phase calculation unit 18, and outputs the determined absolute value |θi1| to the cosine component calculation unit 22 and the maximum value detection unit 21.

[0088] The current amplitude calculation unit 20 uses the α-axis current iα and β-axis current iβ calculated by the three-phase / two-phase conversion unit 15 (Figure 2) to calculate the magnitude iamp of the current Iαβ flowing through the permanent magnet synchronous motor 3 according to the following equation (9).

[0089]

number

[0090] The current amplitude calculation unit 20 outputs the calculated magnitude iamp of the current Iαβ to the DC component calculation unit 23.

[0091] The cosine component calculation unit 22 calculates a cosine component cos(|θi1|) of the absolute value |θi1| calculated by the absolute value calculation unit 19, and outputs the calculated cosine component cos(|θi1|) to the DC component calculation unit .

[0092] The maximum value detection unit 21 detects whether the absolute value |θi1| calculated by the absolute value calculation unit 19 has reached a maximum value, and generates a maximum value detection flag F_theta_max. If the maximum value detection unit 21 detects that the absolute value |θi1| has reached a maximum value, it sets the maximum value detection flag F_theta_max to ON (F_theta_max=1). If the maximum value detection unit 21 does not detect that the absolute value |θi1| has reached a maximum value, it sets the maximum value detection flag F_theta_max to OFF (F_theta_max=0).

[0093] For example, when the following conditions 1 and 2 are both satisfied, the maximum value detection unit 21 determines that the maximum value of the absolute value |θi1| has been detected, and sets the maximum value detection flag F_theta_max to on (F_theta_max=1).

[0094] Condition 1: Δθi1_(n) is less than or equal to 0 (zero). Condition 2: Δθi1_(nk) is greater than 0 (zero). Δθi1_(n) is the time rate of change of the absolute value |θi1| at the nth sample. Δθi1_(nk) is the time rate of change of the absolute value |θi1| at the (nk)th sample, i.e., the sample k samples before the nth sample.

[0095] Δθi1_(n) can be calculated, for example, as follows. The absolute value calculation unit 19 repeatedly calculates the absolute value |θi1| of the first current phase θi1 at a predetermined control period. The maximum value detection unit 21 calculates the difference Δθi1 (=|θi1|_2-|θi1|_1) between the absolute value |θi1| (previous value |θi1|_1) calculated at time t3 and the absolute value |θi1| (present value |θi1|_2) calculated at time t4 after time t3, and calculates the time Δt' (=t4-t3) from time t3 to time t4, and calculates Δθi1_(n) (=Δθi1 / Δt') by dividing Δθi1 by the time Δt'.

[0096] The absolute value calculation unit 19 stores the calculated Δθi1_(n) in the storage unit of the motor control device 4.

[0097] Since Δθi1_(nk) is the time rate of change of the absolute value |θi1| in the (nk)th sample, it can be obtained from the value stored in the storage unit. The value of k is the value at which the maximum value of the absolute value |θi1| can be detected, and is obtained in advance by calculation or experiment.

[0098] If condition 1 is satisfied, that is, if Δθi1_(n) is equal to or less than 0, it means that the absolute value |θi1| in the nth sample is decreasing. On the other hand, if Δθi1_(n) is greater than 0, it means that the absolute value |θi1| in the nth sample is increasing.

[0099] If condition 2 is satisfied, that is, if Δθi1_(nk) is greater than 0, it means that the absolute value |θi1| in the (nk)th sample is increasing. On the other hand, if Δθi1_(nk) is equal to or less than 0, it means that the absolute value |θi1| in the (nk)th sample is decreasing.

[0100] Therefore, when both Condition 1 and Condition 2 are satisfied, it means that the absolute value |θi1| changed from increasing to decreasing at a time between the time of the (nk)th sample and the time of the nth sample. In this way, the maximum value detection unit 21 can detect that the absolute value |θi1| has reached its maximum value.

[0101] DC component calculation unit 23 calculates DC current Iα_DC according to equation (10) using the magnitude iamp of current Iαβ calculated by current amplitude calculation unit 20, the cosine component cos(|θi1|) of the absolute value |θi1| calculated by cosine component calculation unit 22, and a maximum value detection flag F_theta_max set by maximum value detection unit 21, when the following condition 3 is satisfied. DC component calculation unit 23 outputs the calculated DC current Iα_DC to calculation unit 24.

[0102] Condition 3: Maximum value detection flag F_theta_max is on

[0103]

number

[0104] The principle of determining the DC current Iα_DC from equation (10) will be described with reference to FIGS. 6A and 6B.

[0105] 6A and 6B are explanatory diagrams showing the current vector when the magnitude (|θi1|) of the first current phase θi1 is maximum when a DC current is passed through the permanent magnet synchronous motor 3. Fig. 6A shows the current vector whose absolute value |θi1| is maximum when the β-axis current iβ is positive. Fig. 6B shows the current vector whose absolute value |θi1| is maximum when the β-axis current iβ is negative.

[0106] As shown in Figures 6A and 6B, the absolute value |θi1| is maximum when the current Iαβ flowing through the permanent magnet synchronous motor 3 is tangent to the vector locus of the current Ie generated by the influence of the induced voltage E (i.e., when the current Iαβ becomes tangent to the vector locus of the current Ie). At this time, the angle formed by the currents Ie and Iαβ is a right angle. Therefore, as shown in Figures 6A and 6B, the DC current Iα_DC can be calculated based on equation (10) using the magnitude iamp of the current Iαβ and the maximum value of the absolute value |θi1|.

[0107] When calculating the DC current Iα_DC, the magnitude iamp of the current Iαβ and the cosine component cos(|θi1|) of the absolute value |θi1| are the values ​​when the maximum value detection flag F_theta_max is switched from OFF to ON. The storage unit of the motor control device 4 stores the values ​​of iamp and cos(|θi1|) at this time.

[0108] As can be seen from FIG. 6A and FIG. 6B, the absolute value |θi1| becomes maximum twice during one revolution of the current Ie caused by the influence of the induced voltage E. This means that the timing at which the DC current Iα_DC can be calculated occurs twice during one cycle of the current Ie. That is, in this embodiment, the DC current Iα_DC can be calculated and the estimated initial phase θd0 and the estimated initial speed ωe0 can be calculated in a time shorter than one cycle of the current Ie. Therefore, in this embodiment, the rotor position (estimated initial phase θd0) and the rotation speed (estimated initial speed ωe0) in the idling state of the permanent magnet synchronous motor 3 can be calculated in a short time compared to the conventional technology in which the DC current Iα_DC is calculated from the average value of the maximum and minimum values ​​of the α-axis current iα.

[0109] The process executed by the maximum value detection unit 21 and the DC component calculation unit 23 to calculate the DC current Iα_DC will be described with reference to Fig. 7 and Fig. 8. Fig. 7 is an example of a flowchart showing the process for setting the maximum value detection flag F_theta_max. Fig. 8 is an example of a flowchart showing the process for calculating the DC current Iα_DC.

[0110] The process procedure for calculating the DC current Iα_DC shown in Fig. 8 is performed when performing start-up control, and is started, for example, when the voltage command switching unit 10 switches the switching signal SW_signal from on to off (SW_signal = 0). Moreover, the process procedure for calculating this DC current Iα_DC is repeatedly executed at a predetermined control period after the maximum value detection unit 21 performs initial setting. In this initial setting, the maximum value detection flag F_theta_max is set to off.

[0111] The processing of the flowcharts shown in Figures 7 and 8 is executed based on the calculation results of each calculation unit of the spin state estimation unit 14 (for example, the absolute value |θi1| of the first current phase, the time change rate Δθi1_(n) of the absolute value |θi1|, the cosine component cos(|θi1|) of the absolute value |θi1|, and the magnitude iamp of the current Iαβ) that are repeatedly acquired at a predetermined control period.

[0112] As shown in FIG. 8, in step S100, the maximum value detection section 21 executes a process of setting a maximum value detection flag F_theta_max.

[0113] Here, the process of setting the maximum value detection flag F_theta_max executed by the maximum value detection section 21 will be described with reference to FIG.

[0114] As shown in FIG. 7, when the process of setting the maximum value detection flag F_theta_max is started, in step S110, the maximum value detection unit 21 calculates the time rate of change Δθi1_(n) of the absolute value |θi1| in the nth sample, and stores the calculated Δθi1_(n) in the memory unit of the motor control device 4.

[0115] In step S120, maximum value detection unit 21 determines whether Δθi1_(n) calculated in step S110 is equal to or less than 0 (zero) (i.e., whether condition 1 is satisfied). If Δθi1_(n) is equal to or less than 0, the process proceeds to step S130. If Δθi1_(n) is greater than 0, the process proceeds to step S150.

[0116] In step S130, maximum value detection unit 21 determines whether or not the time rate of change Δθi1_(nk) of the absolute value |θi1| in the (nk)th sample, which was calculated in step S110 and stored in the memory unit of motor control device 4, is greater than 0 (zero) (i.e., whether or not condition 2 is satisfied). If Δθi1_(nk) is greater than 0, the process proceeds to step S140. If Δθi1_(nk) is equal to or less than 0, the process proceeds to step S150.

[0117] In step S140, the maximum value detection section 21 sets the maximum value detection flag F_theta_max to ON (F_theta_max=1), and ends the process of setting the maximum value detection flag F_theta_max shown in FIG.

[0118] In step S150, the maximum value detection section 21 sets the maximum value detection flag F_theta_max to OFF (F_theta_max=0), and ends the process of setting the maximum value detection flag F_theta_max shown in FIG.

[0119] When the process of setting the maximum value detection flag F_theta_max shown in Fig. 7 is completed, the process of step S210 in Fig. 8 is executed. The processes after step S210 in Fig. 8 are executed by the DC component calculation unit 23.

[0120] In step S210 in Fig. 8, the DC component calculation unit 23 determines whether or not the maximum value detection flag F_theta_max is on (i.e., whether or not condition 3 is satisfied). If the maximum value detection flag F_theta_max is currently set to on, the process proceeds to step S220. If the maximum value detection flag F_theta_max is currently set to off, the process proceeds to step S100, and the process of setting the maximum value detection flag F_theta_max (Fig. 7) is executed.

[0121] In step S220, the DC component calculation unit 23 holds the value of the cosine component cos(|θi1|) of the absolute value |θi1| and the value of the magnitude iamp of the current Iαβ when the maximum value detection flag F_theta_max was switched from off to on. Then, the DC component calculation unit 23 stores the held value of cos(|θi1|) and the value of iamp in the storage unit of the motor control device 4.

[0122] In step S230, the DC component calculation unit 23 calculates the DC current Iα_DC based on equation (10) using the cosine component cos(|θi1|) of the absolute value |θi1| and the magnitude iamp of the current Iαβ held in step S220. Then, the DC component calculation unit 23 stores the calculated DC current Iα_DC in the storage unit of the motor control device 4, and ends the processing of the flowchart shown in Fig. 8 for the current control period.

[0123] The DC component calculation unit 23 outputs the DC current Iα_DC calculated in step S230 to the calculation unit 24 (FIG. 4). The DC component calculation unit 23 holds the calculated DC current Iα_DC, for example, until the switching signal SW_signal switches from off to on, that is, until the state switches from the idling state to the normal operation state, and outputs it to the calculation unit 24.

[0124] In this way, when it is detected that the absolute value |θi1| has reached its maximum value by the maximum value detection flag F_theta_max switching from off to on, the DC current Iα_DC is calculated based on the magnitude iamp of the current Iαβ when the absolute value |θi1| has reached its maximum value and the cosine component cos(|θi1|) of the absolute value |θi1|.

[0125] Hereinafter, with reference to FIG. 9, an example of the operation and the effects of the motor control device 4 according to this embodiment in an idling state in which the rotor of the permanent magnet synchronous motor 3 is idling will be described.

[0126] Figure 9 is a diagram showing the time series changes of each parameter calculated by the motor control device 4 in this embodiment (α-axis current iα, β-axis current iβ, current value iα_0 calculated by the calculation unit 24, absolute value |θi1| of the first current phase, DC current Iα_DC, second current phase θi2, and estimated initial phase θd0) and the phase θd (induced voltage phase θd) of the induced voltage E of the permanent magnet synchronous motor 3.

[0127] In the following, in order to clarify the effects of the present embodiment, the motor control device 4 according to the present embodiment will be described in comparison with a motor control device in a comparative example. The motor control device in the comparative example is a conventional motor control device that calculates the DC current Iα_DC from the average value of the maximum and minimum values ​​of the α-axis current iα. Note that the operation of the permanent magnet synchronous motor 3 is the same in this embodiment and the comparative example.

[0128] The motor control device in the comparative example calculates the DC current Iα_DC in accordance with the following steps 1 and 2 instead of the above conditions 1 to 3 and equation (10).

[0129] Step 1: The maximum value iα_max and minimum value iα_min of the α-axis current are detected and stored in the memory unit of the motor control device.

[0130] Step 2: If both the maximum value iα_max and the minimum value iα_min of the α-axis current are detected in step 1, the DC current Iα_DC is calculated using the maximum value iα_max and minimum value iα_min of the α-axis current stored in the memory unit, for example based on equation (11).

[0131]

number

[0132] In equation (11), the DC current Iα_DC is calculated from the average value of the maximum value iα_max and the minimum value iα_min of the α-axis current.

[0133] Figure 9 shows six graphs, from graph (a) to graph (f). The horizontal axis of these graphs indicates time (elapsed time).

[0134] Graph (a) shows the α-axis current iα and the β-axis current iβ calculated by the three-phase / two-phase conversion unit 15, and the current value iα_0 calculated by the calculation unit .

[0135] Graph (b) shows the absolute value |θi1| of the first current phase calculated by absolute value calculation section 19.

[0136] Graph (c) shows the DC current Iα_DC calculated by the DC component calculation unit 23 in this embodiment, and the DC current Iα_DC calculated by procedure 1 and procedure 2 in the comparative example.

[0137] The graph (d) shows the second current phase θi2 calculated by the second current phase calculation unit 25.

[0138] The graph (e) shows the induced voltage phase θd of the permanent magnet synchronous motor 3.

[0139] The graph (f) shows the estimated initial phase θd0 calculated by the spin phase estimator 27.

[0140] FIG. 9 shows a time series change after the switching signal SW_signal is switched from on to off when the permanent magnet synchronous motor 3 is in an idling state.

[0141] Time t0 is the time when the process shown in the flowchart of FIG. 8 (the process of calculating the direct current Iα_DC) is started.

[0142] Time t1 is the time when the maximum value detection unit 21 detects that the absolute value |θi1| of the first current phase has reached a maximum value, and the maximum value detection flag F_theta_max is switched from OFF to ON.

[0143] Time t2 is the time when the motor control device in the comparative example detects the minimum value iα_min of the α-axis current and holds the minimum value iα_min.

[0144] Time t3 is the time when maximum value detection section 21 detects that the absolute value |θi1| of the first current phase has become maximum again.

[0145] Time t4 is the time when the motor control device in the comparative example detects the maximum value iα_max of the α-axis current and holds the maximum value iα_max.

[0146] As shown in graph (a), in this embodiment, from time t0 to time t1, that is, until the maximum value detection flag F_theta_max switches from off to on, the DC component calculation unit 23 does not calculate the DC current Iα_DC, so the α-axis current iα and the current value iα_0 calculated by the calculation unit 24 match each other. After time t1, that is, after the maximum value detection flag F_theta_max switches from off to on, the calculation unit 24 calculates the current value iα_0 based on the DC current Iα_DC and the α-axis current iα calculated by the DC component calculation unit 23. The current value iα_0 is a value obtained by subtracting the DC current Iα_DC from the α-axis current iα.

[0147] On the other hand, in the comparative example, procedure 1 is executed at time t2, the minimum value iα_min of the α-axis current iα is detected, and the minimum value iα_min is held. Then, procedure 1 is executed at time t4, the maximum value iα_max of the α-axis current iα is detected, and the maximum value iα_max is held.

[0148] As shown in graph (b), in this embodiment, the absolute value |θi1| of the first current phase increases from time t0 to time t1 and reaches a maximum value at time t1. The absolute value |θi1| of the first current phase decreases from time t1 to time t2 and increases again from time t2 to time t3. The absolute value |θi1| of the first current phase reaches a maximum value again at time t3 and decreases again from time t3 to time t4. After time t4, the absolute value |θi1| of the first current phase repeats the change described above.

[0149] As shown in graph (c), in this embodiment, the maximum value detection flag F_theta_max is off and the DC current Iα_DC is not calculated from time t0 to time t1, so the DC current Iα_DC is 0. At time t1, the absolute value |θi1| of the first current phase becomes maximum, so the DC current Iα_DC is calculated and the calculated DC current Iα_DC is held.

[0150] On the other hand, in the comparative example, the minimum value iα_min of the α-axis current iα is detected at time t2, and the maximum value iα_max of the α-axis current iα is detected at time t4, so that the DC current Iα_DC is calculated at time t4.

[0151] That is, the DC current Iα_DC is calculated at time t1 in this embodiment and at time t4 in the comparative example. Therefore, in this embodiment, the DC current Iα_DC can be calculated at an earlier time than in the comparative example, that is, earlier than in the comparative example by the time (time t4-time t1), and the rotor position (estimated initial phase θd0) and rotational speed (estimated initial speed ωe0) in the idling state of the permanent magnet synchronous motor 3 can be calculated in a short time.

[0152] As shown in graph (d), in this embodiment, the α-axis current iα and the current value iα_0 calculated by the calculation unit 24 match each other from time t0 to time t1, so that the θi1 calculated by the first current phase calculation unit 18 and the second current phase θi2 calculated by the second current phase calculation unit 25 match each other. At time t1, the DC current Iα_DC is calculated, so the current value iα_0 calculated by the calculation unit 24 is the value obtained by subtracting the DC current Iα_DC from the α-axis current iα. Therefore, after time t1, the second current phase calculation unit 25 calculates the second current phase θi2. The second current phase θi2 is the angle between the current Ie generated by the induced voltage E and the α-axis (FIGS. 3A and 3B). Graph (e) shows an example of the change over time in the induced voltage phase θd of the permanent magnet synchronous motor 3 in this embodiment, i.e., the angle (phase of the induced voltage E) between the induced voltage E generated by the rotation of the rotor of the permanent magnet synchronous motor 3 and the α axis.

[0153] As shown in the graph (f), in this embodiment, from time t0 to time t1, as described above, the second current phase θi2 calculated by the second current phase calculation unit 25 coincides with θi1 calculated by the first current phase calculation unit 18. Therefore, a value equivalent to a value obtained by adding the phase difference Δθi between the second current phase θi2 and the phase of the induced voltage E calculated by the formula (6) to the first current phase θi1 is calculated as the estimated initial phase θd0. After time t1, the value calculated by the second current phase calculation unit 25 becomes the second current phase θi2 (FIGS. 3A and 3B), which is the angle between the current Ie generated by the influence of the induced voltage E and the α axis, so that the estimated initial phase θd0, which is an estimated value of the induced voltage phase θd, can be calculated by the formula (7).

[0154] The effects of the motor control device 4 according to this embodiment will be described.

[0155] In conventional motor control devices, the short-circuit current of the motor windings that flows when the inverter is in short-circuit operation is determined by the motor's induced voltage and the winding resistance and inductance, so depending on the idling speed, overcurrent may occur during short-circuit operation. Also, because a special PWM control mode and current detection process are used to detect the bus current flowing through the shunt resistor, the calculations to calculate the motor's rotor position and rotation speed become complicated, and errors are likely to occur in the estimation results.

[0156] In contrast, in the motor control device 4 according to the present embodiment, the idling state estimation unit 14 calculates a first current phase θi1 which is the phase of the current Iαβ flowing through the permanent magnet synchronous motor 3 in an idling state, calculates a DC current Iα_DC using the magnitude iamp of the current Iαβ when the magnitude of the first current phase θi1 is maximum and the magnitude of the first current phase θi1, calculates a second current phase θi2 which is the phase of the current Ie generated by the idling of the permanent magnet synchronous motor 3 using the DC current Iα_DC and the current Iαβ, and calculates the rotor position and rotational speed (estimated initial phase θd0 and estimated initial speed ωe0) of the permanent magnet synchronous motor 3 in an idling state using the second current phase θi2. The motor control device 4 according to the present embodiment has such a configuration and calculates the rotor position and rotational speed of the permanent magnet synchronous motor 3 by simple calculation with little error without using a position detector, so that the rotor position and rotational speed of the permanent magnet synchronous motor 3 can be calculated with higher accuracy and in a shorter time.

[0157] The present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the above-described embodiments have been described in detail to clearly explain the present invention, and the present invention is not necessarily limited to an embodiment having all of the configurations described. It is also possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. It is also possible to delete a part of the configuration of each embodiment, or to add or replace another configuration.

[0158] Further, each component of the motor control device 4 according to the present invention may be realized in hardware, for example, by designing a part or all of them as an integrated circuit. Further, each component may be realized in software, for example, by having a processor interpret and execute a program that realizes each function. Information such as a program, table, file, measurement information, and calculation information that realizes each function can be recorded in a recording device such as a memory, a hard disk drive, and an SSD (Solid State Drive), or a recording medium such as an IC card, an SD card, and a DVD. Thus, each component of the control device according to the present invention can realize each function as a processing unit, a processing unit, a program module, or the like. [Explanation of symbols]

[0159] 1...DC power supply, 2...inverter, 3...permanent magnet synchronous motor, 4...motor control device, 5...shunt resistor, 6...amplifier, 7...speed control unit, 8...d-axis current command generation unit, 9...current control unit, 10...voltage command switching unit, 11...2-phase / 3-phase conversion unit, 12...voltage command generation unit, 13...speed / phase estimator, 14...idling state estimator, 15...3-phase / 2-phase conversion unit, 16...current reproduction calculation unit, 17...control signal generation unit, 18...first current phase calculation unit, 19...absolute value calculation unit, 20...current amplitude calculation unit, 21...maximum value detection unit, 22...cosine component calculation unit, 23...DC component calculation unit, 24...calculation unit, 25...second current phase calculation unit, 26...idling speed estimator, 27...idling phase estimator, 35...calculation unit, 50...DC voltage detector.

Claims

1. The inverter is configured to control an inverter that supplies AC power to the permanent magnet synchronous motor, thereby controlling the operation of the permanent magnet synchronous motor, a voltage command generating unit that outputs a voltage command to cause a direct current to flow through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in an idling state; an idling state estimation unit that calculates a rotor position and a rotation speed of the permanent magnet synchronous motor in the idling state; a speed / phase estimation unit that estimates a rotor position and a rotation speed of the permanent magnet synchronous motor by using the rotor position and the rotation speed calculated by the idling state estimation unit as initial values; Equipped with A current obtained by adding a current generated by the idling of the permanent magnet synchronous motor to the DC current flows through the permanent magnet synchronous motor in the idling state, The slip state estimation unit is a first current phase calculation unit that calculates a first current phase, which is a phase of a current flowing through the permanent magnet synchronous motor in the idling state; a DC component calculation unit that calculates the DC current by using a magnitude of the current when the magnitude of the first current phase is maximum and a magnitude of the first current phase; a second current phase calculation unit that calculates a second current phase, which is a phase of a current generated by an idling of the permanent magnet synchronous motor, by using the DC current and the current; an idling speed / phase estimation unit that calculates a rotor position and a rotation speed of the permanent magnet synchronous motor in the idling state by using the second current phase; Equipped with A motor control device comprising:

2. the second current phase calculation unit calculates the second current phase by using a current value obtained by excluding a contribution of the DC current from the current; The motor control device according to claim 1 .

3. The permanent magnet synchronous motor is a motor having multiple phases, the voltage command generating unit outputs the voltage command for causing the DC current to flow through one phase of the plurality of phases of the permanent magnet synchronous motor. The motor control device according to claim 1 .

4. The current flowing through the permanent magnet synchronous motor in the idling state is expressed by an α-axis current which is a current in the α-axis direction and a β-axis current which is a current in the β-axis direction through a three-phase / two-phase conversion, a first current phase calculation unit calculates the first current phase by using the α-axis current and the β-axis current; The motor control device according to claim 1 .

5. The first current phase is an angle between the current and the α axis. The motor control device according to claim 4.

6. The second current phase is an angle between a current generated by idling of the permanent magnet synchronous motor and the α-axis. The motor control device according to claim 4.

7. the second current phase calculation unit calculates the second current phase by using a current value obtained by excluding the DC current from the α-axis current. The motor control device according to claim 4.

8. 1. A motor control method for controlling an inverter that supplies AC power to a permanent magnet synchronous motor, thereby controlling operation of the permanent magnet synchronous motor, comprising: a voltage command generating step of outputting a voltage command to cause a direct current to flow through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in an idling state; an idling state estimation step of calculating a rotor position and a rotation speed of the permanent magnet synchronous motor in an idling state; a speed / phase estimation step of estimating a rotor position and a rotation speed of the permanent magnet synchronous motor by using the rotor position and the rotation speed calculated in the idling state estimation step as initial values; Equipped with In a permanent magnet synchronous motor that is in an idling state, a current flows that is the sum of the direct current and the current generated by the idling of the permanent magnet synchronous motor. The slip state estimation process includes: a first current phase calculation step of calculating a first current phase which is a phase of a current flowing through a permanent magnet synchronous motor in an idling state; a DC component calculation step of calculating a DC current by using a magnitude of the current when the magnitude of the first current phase is maximum and a magnitude of the first current phase; a second current phase calculation step of calculating a second current phase, which is a phase of a current generated by an idling of the permanent magnet synchronous motor, by using the DC current and the current; an idling speed / phase estimation step of calculating a rotor position and a rotation speed of the permanent magnet synchronous motor in an idling state by using the second current phase; Equipped with A motor control method comprising:

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