ENGINE CONTROL DEVICE AND ENGINE CONTROL METHOD

Abstract

A motor control device is to be provided that is capable of calculating the rotor position and speed of a motor with high accuracy and in a short time. A motor control device 4 according to the present invention comprises a speed / phase estimation unit 13, which estimates the rotor position and speed of a motor 3 using values ​​calculated by a freewheeling state estimation unit 14. The freewheeling state estimation unit 14 comprises: a first current phase calculation unit 18, which calculates a first phase θ i1 calculated, which represents the phase of a current Iαβ flowing through the motor 3 in a free-running state; a DC component calculation unit 23, which calculates a DC current I flowing through the motor 3 in a free-running state α_DC using the current Iαβ and the first phase θ i1 calculated at the time when the amount of the first phase θ i1maximum; a second current phase calculation unit 25, which is a second phase θ i2 calculated which represents the phase of a current Ie generated by the freewheeling of motor 3, using the direct current I α_DC and the current Iαβ; and freewheeling speed / phase estimation units 26, 27, which determine the rotor position and the speed of the motor 3 in the freewheeling state using the second phase θ i2 calculate.

Description

Technical field

[0001] The present invention relates to a device and a method for controlling the operation of a motor. State of the art

[0002] Motor drive systems comprising an inverter, which converts direct current (DC) power to alternating current (AC) power, and a permanent magnet synchronous motor are widely used in household appliances and industrial equipment. To drive such a permanent magnet synchronous motor with high efficiency, information about the motor's rotor position is generally required. The motor's rotor position can be directly detected using a position detector, such as an encoder; however, this method presents challenges in terms of cost and reliability. Therefore, in recent years, position sensorless control, which detects the rotor position of a permanent magnet synchronous motor without the use of a position detector, has been proposed and implemented in various products.

[0003] One of the challenges in position sensor-less control of a permanent magnet synchronous motor is a method for restarting from a state where the rotor is coasting (referred to as a "freewheel start"). For example, in a motor such as that of a washing machine, the motor may already be rotating before starting due to the inertia of the load—that is, it may be coasting. In such a case, if no information such as rotor position, speed, and direction of rotation is available in the coasting state, it is necessary to wait until the motor stops or to force a braking control to stop the motor's rotation and then restart it from the stopped state. This presents a problem because the time required for the restart becomes considerable.

[0004] Accordingly, for example, as with the motor control devices described in patent literature 1 and patent literature 2, a technique was developed which focuses on the induced voltage generated during the freewheeling of a permanent magnet synchronous motor, short-circuits the motor windings by means of an inverter and estimates the rotor position and the like based on the current flowing at that time.

[0005] In the motor control device described in patent literature 1, three upper branch elements (or lower branch elements) are switched on simultaneously among the switching elements that form the motor drive inverter in order to pass a short-circuit current through the motor windings, and the rotor position and speed are calculated based on the acquired information of the three-phase motor currents.

[0006] In the motor control device described in patent literature 2, elements of different branches for two phases of the motor drive inverter are switched on and off simultaneously, the DC-side bus current of the inverter is detected by a shunt resistor, and the rotor position and speed of the motor are calculated. List of oppositions patent literature Patent literature 1: JP 2015-73361 Patent literature 2: JP 2018-170928 Summary of the invention: Technical problem

[0007] Conventional techniques, such as the motor control devices described in patent literature 1 and patent literature 2, exhibit the following problems.

[0008] In the motor control device described in patent literature 1, the short-circuit current of the motor windings, which flows during the short-circuit operation of the inverter, is determined by the induced voltage of the motor as well as the resistance and inductance of the windings, so that an overcurrent can occur depending on the free-running speed during short-circuit operation. The occurrence of an overcurrent has an undesirable effect on the motor.

[0009] In the motor control device described in patent literature 2, because a special PWM control mode and special current sensing processing are used to detect the bus current flowing through the shunt resistor, the calculations for determining the rotor position and speed of the motor become complicated, and errors are likely to occur in the estimation results.

[0010] The objective of the present invention was formulated with regard to the above-mentioned problems of the prior art and is to provide a motor control device and a motor control method that are capable of calculating the rotor position and speed of a motor with higher accuracy and in a shorter time. Solution to the problem

[0011] 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 alternating current power to the permanent magnet synchronous motor, and comprises: a voltage command generation unit that outputs a voltage command to pass a direct current through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in a free-running condition; a free-running condition estimation unit that calculates the rotor position and speed of the permanent magnet synchronous motor in the free-running condition; and a speed / phase estimation unit that estimates the rotor position and speed of the permanent magnet synchronous motor using the rotor position and speed calculated by the free-running condition estimation unit as initial values.In the permanent magnet synchronous motor in freewheeling condition, a current flows which is obtained by adding a current generated by the freewheeling of the permanent magnet synchronous motor to the direct current.The freewheeling state estimation unit comprises: a first current phase calculation unit, which calculates a first current phase that is the phase of the current flowing through the permanent magnet synchronous motor in the freewheeling state; a DC component calculation unit, which 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 at its maximum; a second current phase calculation unit, which calculates a second current phase that is the phase of the current generated by the freewheeling of the permanent magnet synchronous motor, using the DC current and the current; and a freewheeling speed / phase estimation unit, which calculates the rotor position and speed of the permanent magnet synchronous motor in the freewheeling state using the second current phase.

[0012] 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 alternating current power to the permanent magnet synchronous motor, and comprises: a voltage command generation step for outputting a voltage command to pass a direct current through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in a free-running condition; a free-running condition estimation step for calculating the rotor position and speed of the permanent magnet synchronous motor in the free-running condition; and a speed / phase estimation step for estimating the rotor position and speed of the permanent magnet synchronous motor using the rotor position and speed calculated in the free-running condition estimation step as initial values.In the permanent magnet synchronous motor in freewheeling condition, a current flows which is obtained by adding a current generated by the freewheeling of the permanent magnet synchronous motor to the direct current.The freewheeling state estimation step comprises: a first current phase calculation step to calculate a first current phase, which is the phase of the current flowing through the permanent magnet synchronous motor in the freewheeling state; a DC component calculation step to calculate 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 at its maximum; a second current phase calculation step to calculate a second current phase, which is the phase of the current generated by the freewheeling of the permanent magnet synchronous motor, using the DC current and the current; and a freewheeling speed / phase estimation step to calculate the rotor position and speed of the permanent magnet synchronous motor in the freewheeling state using the second current phase. Advantageous effects of the invention

[0013] According to the present invention, it is possible to provide a motor control device and a motor control method that are able to calculate the rotor position and speed of a motor with higher accuracy and in a shorter time. Brief description of the drawings Fig. Figure 1 shows a diagram schematically illustrating the overall structure of an engine control system including an engine control device according to an embodiment of the present invention. Fig. Figure 2 shows a functional block diagram illustrating the processing contents of the motor control device. Fig. Figure 3A shows an explanatory diagram illustrating a current vector when a direct current is passed through a permanent magnet synchronous motor. Fig. 3B shows a diagram that displays a current value i calculated by a computation unit. α_0 shows. Fig. Figure 4 shows a function block diagram illustrating the processing contents of a freewheeling state estimation unit. Fig. Figure 5 shows a vector diagram illustrating an induced voltage E generated in a freewheeling state of a permanent magnet synchronous motor and a current le generated due to the influence of the induced voltage E. Fig. Figure 6A shows an explanatory diagram that displays a current vector when the magnitude of a first current phase θ i1 The maximum value is reached when a direct current is passed through a permanent magnet synchronous motor, and is a diagram showing a current vector when the absolute value is |0 i1 | is maximal when a β-axis current i β is positive. Fig. 6B shows an explanatory diagram that shows a current vector when the magnitude of a first current phase θ i1The maximum value is reached when a direct current is passed through a permanent magnet synchronous motor, and is a diagram showing a current vector when the absolute value |θ i1 | is maximal when a β-axis current i β is negative. Fig. Figure 7 shows an example of a flowchart illustrating a processing flow for setting a maximum value detection flag F_theta_max. Fig. Figure 8 shows an example of a flowchart illustrating a processing sequence for calculating a direct current I. α_DC shows. Fig. Figure 9 shows a diagram showing the time changes of each parameter calculated by the motor control device according to the present embodiment and a phase θ. d shows an induced voltage of the permanent magnet synchronous motor. Description of embodiments

[0014] The motor control device according to the present embodiment includes a freewheeling state estimation unit, calculates one phase of a current generated by the freewheeling of the motor (a second current phase θ). i2 ) and calculates a rotor position and a speed of the motor in a free-running condition using this phase. With such a configuration, the motor control device according to the present embodiment calculates the rotor position and speed of the motor with simple calculations that are less prone to error, without using a position detector, so that the rotor position and speed of the motor can be calculated with higher accuracy and in a shorter time.

[0015] A motor control device and a motor control method according to an embodiment of the present invention are described below with reference to the drawings. In the following embodiment, an example is described in which a control target of the motor control device is a permanent magnet synchronous motor (PMSM). embodiment

[0016] Fig. Figure 1 shows a diagram schematically illustrating the overall structure of an engine control system including the engine control device according to the present embodiment.

[0017] The in Fig. The motor control system shown comprises as its main components the motor control device 4 according to the present embodiment, a permanent magnet synchronous motor 3, a DC power supply 1 and an inverter 2.

[0018] The motor control device 4 controls the operation of the permanent magnet synchronous motor 3 by generating a control signal for the inverter 2 and controlling the inverter 2. The motor control device 4 can be implemented using a semiconductor computing device such as a microcomputer or a DSP (digital signal processor).

[0019] The permanent magnet synchronous motor 3 comprises a rotor in which a permanent magnet is integrated and is controlled by the motor control device 4 via the inverter 2. The permanent magnet synchronous motor 3 is a multi-phase motor. In the present embodiment, the permanent magnet synchronous motor 3 is, for example, a three-phase motor.

[0020] The DC power supply 1 can be configured by any device. For example, the DC power supply 1 can use a power conversion device (for example, a diode rectifier, a stabilized power supply, or the like) that converts AC power received from an AC power supply such as a commercial AC power supply (not shown) into DC power, a battery, or the like.

[0021] In the present embodiment, the inverter 2 controls the operation of the permanent magnet synchronous motor 3 by performing PWM control (pulse width modulation). The inverter 2 converts direct current power from the direct current supply 1 into alternating current power and supplies this alternating current power to the permanent magnet synchronous motor 3.

[0022] Inverter 2 contains a multitude of series circuits in which two branch circuits, in other words an upper branch and a lower branch, are connected in series. Each branch circuit (upper branch and lower branch) is configured with a semiconductor switching element (IGBT, MOSFET, or the like) and an antiparallel diode. The multitude of series circuits is connected between a pair of positive and negative terminals of the DC power supply 1.

[0023] The inverter 2 comprises series connections corresponding to the number of AC output phases. For example, in the present embodiment, the inverter 2 is a three-phase inverter containing three series connections for the three phases. The upper branch of the inverter is connected to a high-potential side of the DC power supply 1, and the lower branch is connected to a low-potential side of the DC power supply 1. A connection point where the upper and lower branches are connected in series is connected to an AC power terminal. The permanent magnet synchronous motor 3 is connected to this AC power terminal.

[0024] A low-potential bus of inverter 2 is connected to a negative terminal of the DC power supply 1 via a shunt resistor 5 for current sensing. A current sensing signal detected by the shunt resistor 5 is fed into the motor control device 4 via an amplifier 6. A signal output by the amplifier 6 to the motor control device 4 is converted into a digital signal for digital processing in the motor control device 4 by a sample-and-hold circuit, an analog-to-digital converter, and the like (not shown). That is, the shunt resistor 5 and the amplifier 6 form a DC current detector that detects a DC current flowing through the low-potential bus of inverter 2 and outputs a current sensing signal to the motor control device 4. It should be noted that a different current sensing device, such as a current sensor, can be used instead of the shunt resistor 5.

[0025] A high-potential bus of inverter 2 is connected to a positive terminal of the DC power supply 1. A DC voltage detector 50 is installed between the high-potential and low-potential buses of inverter 2. This detector senses a DC voltage between the high-potential and low-potential buses and outputs a DC voltage detection signal to the motor control device 4. A signal output by the DC voltage detector 50 to the motor control device 4 is converted into a digital signal in the same way as a signal output by the DC current detector to the motor control device 4.

[0026] It should be noted that, as will be described later, the motor control device 4 according to the present embodiment performs position sensor-less control, that is, control for detecting and synchronizing a rotor position of the permanent magnet synchronous motor 3 without using a position detector. Therefore, the permanent magnet synchronous motor 3 does not contain a magnetic pole position detector such as a Hall element that detects the position of the rotor or the rotating shaft.

[0027] Fig. Figure 2 shows a functional block diagram illustrating the processing contents of the motor control device 4. It should be noted that, as described above, the motor control device 4 can be configured by a semiconductor computing device such as a microcomputer or a DSP, and each function is implemented by executing a predetermined program.

[0028] It should be noted that the motor control device 4 can apply a moving average process or a low-pass filter process to values ​​used for various calculations in order to avoid the influence of disturbances and noise.

[0029] As in Fig. As shown in Figure 2, the motor control device 4 comprises, 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 2-phase / 3-phase conversion unit 11, a speed / phase estimation unit 13, a voltage command generation unit 12, a freewheeling state estimation unit 14, a 3-phase / 2-phase conversion unit 15, a current reconstruction calculation unit 16, a control signal generation unit 17, and a calculation unit 35. Furthermore, the motor control device 4 includes a memory unit (not shown) and can store input data and values ​​obtained through calculation.

[0030] The motor control device 4 calculates a voltage command to be applied to the permanent magnet synchronous motor 3 by vector control using dq axes and, based on this voltage command, generates a control signal (for example, a PWM control signal (pulse width modulation)) for the inverter 2, thereby controlling the operation of the permanent magnet synchronous motor 3. The motor control device 4 performs operational control in a normal operating state of the permanent magnet synchronous motor 3 (normal operating control) and transition control from a freewheeling state, in which the rotor of the permanent magnet synchronous motor 3 spins, to the normal operating state (starting control).

[0031] The following describes the normal operating control and the start control from a freewheeling state, which are carried out by the motor control device 4 on the permanent magnet synchronous motor 3. <Normaler Betriebszustand>

[0032] First, the operation of each functional block during operational control is described in a normal operating state (normal operating control).

[0033] The current reconstruction calculation unit 16 uses a current sensing signal i sh , which is output by the amplifier 6 forming the DC detector, and three-phase voltage commands V u *, V v *, V w *, which are output by the 2-phase / 3-phase conversion unit 11 to the control signal generation unit 17 to convert three-phase motor currents i u , i v , i w to reconstruct the currents flowing from inverter 2 to permanent magnet synchronous motor 3. The current reconstruction calculation unit 16 can calculate the three-phase motor currents i u , i v , i w from the current sensing signal i sh(that is, the current sensing signal detected by the shunt resistor 5) reconstruct using a known method. The current reconstruction calculation unit 16 outputs the reconstructed three-phase motor currents i u , i v , i w to the 3-phase / 2-phase conversion unit 15.

[0034] It should be noted that in the present embodiment, a method is used to reduce costs in which the current reconstruction calculation unit 16 calculates the three-phase motor currents i u , i v , i w from the current sensing signal i detected by the shunt resistor 5 shThe motor control device 4 reconstructs the current and outputs these three-phase motor currents to the 3-phase / 2-phase conversion unit 15, but the motor control device 4 does not have to use this method. For example, instead of the shunt resistor 5, a current sensing device such as a current sensor can be used to detect an alternating current that is an output of the inverter 2, and the three-phase motor currents detected by the current sensing device can be displayed. u , i v , i w can be entered into the 3-phase / 2-phase conversion unit 15.

[0035] The 3-phase / 2-phase conversion unit 15 performs a 3-phase / 2-phase conversion and converts the three-phase motor currents reconstructed by the current reconstruction calculation unit 16. u , i v , i w into an α-axis current i α and a β-axis current i β Specifically, the 3-phase / 2-phase conversion unit 15 calculates an α-axis current i.α , a β-axis current i β , a DC-axis current i dc and a qc-axis stream i qc based on the following equations (1) and (2), based on the three-phase motor currents i reconstructed by the current reconstruction calculation unit 16 u , i v , i w and phase information θ d_est , which were estimated by the velocity / phase estimation unit 13. The α-axis current i α , the β-axis current i β , the DC axis current i dc and the qc-axis current i qc These are motor currents in the directions of the α-axis, β-axis, dc-axis and qc-axis, respectively. [Equation 1] (iαiβ)=23(cos(0)cos(2π / 3)cos(4π / 3)sin(0)sin(2π / 3)sin(4π / 3))(iuiviw) [Equation 2] (idciqc)=(cos(θd_est)sin(θd_est)−sin(θd_est)cos(θd_est))(iαiβ)

[0036] Equation (1) represents the so-called 3-phase / 2-phase conversion. Equation (2) represents the conversion to a rotating coordinate system.

[0037] The dc-qc axis is an estimated axis (axis of a virtual coordinate system) of a vector control system based on estimated position information, and the dq axis is a motor rotor axis (axis of a coordinate system attached to the rotor). In the present embodiment, an axis error (phase deviation) between the dq axis and the dc-qc axis is denoted as Δθc.

[0038] The speed / phase estimation unit 13 estimates a rotor position and a rotational speed of the permanent magnet synchronous motor 3 using a dc shaft current i dc , of a qc-axis stream i qc , of a DC axis voltage command V dc * and a qc-axis voltage command V qc * and provides this as phase information θ d_estor estimated velocity ω est The velocity / phase estimation unit 13 can provide the phase information θ. d_est and the estimated velocity ω est (that is, the rotor position and rotational speed) using a known method.

[0039] The calculation unit 35 calculates a deviation (difference) between a velocity command ω* and the velocity ω estimated by the velocity / phase estimation unit 13. est The speed command ω* is generated by a functional unit (not shown) of the motor control device 4 in response to an external command.

[0040] The speed control unit 7 generates a qc-axis current command i qc* , so that the deviation calculated by the calculation unit 35 (difference between the speed command ω* and the estimated speed ω) est) approaches 0 (zero), that is, so that the estimated velocity ω est approximates the speed command ω*.

[0041] The d-axis current command generation unit 8 generates a dc-axis current command i dc* to minimize three-phase motor currents i u , i v , i w using a known method.

[0042] The current control unit 9 uses the dc-axis current command i given by the d-axis current command generation unit 8. dc* , the qc-axis current command i given by the speed control unit 7 qc* , a DC axis current sensing value i dc and a qc-axis current sensing value i qc , which are given by the 3-phase / 2-phase conversion unit 15, the speed command ω* and motor constants (for example, a torque constant and a back EMF constant) to generate a dc-axis voltage command V dc* and a qc-axis voltage command V qc * to calculate and output. The current control unit 9 calculates the DC axis voltage command V. dc * and the qc-axis voltage command V qc * using a known method.

[0043] Although not shown in the figure, the motor control device 4 includes a functional unit that determines, based on the rotational speed of the rotor or the like, whether the permanent magnet synchronous motor 3 is in a normal operating state or a free-running state. This component outputs the result of this determination as a control switching signal to the voltage command switching unit 10.

[0044] The voltage command switching unit 10 sends either the dc-qc axis voltage commands V calculated by the current control unit 9 to the 2-phase / 3-phase conversion unit 11. dc *, V qc* or the α-β-axis voltage commands V issued by the voltage command generation unit 12 α *, V β * off, depending on whether a normal operating state or a freewheeling state exists based on the control switching signal. The voltage command generation unit 12 is described later.

[0045] Specifically, in normal operating conditions, the voltage command switching unit 10 sets a switching signal SW_signal to On (SW_signal=1) and outputs the dc-qc axis voltage commands V calculated by the current control unit 9. dc *, V qc * to the 2-phase / 3-phase conversion unit 11. Furthermore, in the freewheeling state (i.e., during the start-up control), 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 V issued by the voltage command generation unit 12. α *, V β* to the 2-phase / 3-phase conversion unit 11.

[0046] In normal operating conditions, the 2-phase / 3-phase conversion unit 11 uses the DC-QC axis voltage commands V calculated by the current control unit 9 and entered via the voltage command switching unit 10. dc *, V qc * and the phase information θ entered by the velocity / phase estimation unit 13 d_est , to issue three-phase voltage commands V u *, V v *, V w * to be calculated and output according to the following equations (3) and (4). In the freewheeling state, the 2-phase / 3-phase conversion unit 11 uses the α-β-axis voltage commands V output by the voltage command generation unit 12 and input via the voltage command switching unit 10. α *, V α *, to control the three-phase voltage commands V u *, V v *, V w * to be calculated and output according to equation (4). [Equation 3] (Vα*Vβ*)=(cos(θd_est)−sin(θd_est)sin(θd_est)cos(θd_est))(Vdc*Vqc*) [Equation 4] (Vu*Vv*Vw*)=(cos(0)sin(0)cos(2π / 3)sin(2π / 3)cos(4π / 3)sin(4π / 3))(Vα*Vβ*)

[0047] Equation (3) represents the conversion from a rotating coordinate system to a fixed coordinate system. Equation (4) represents the so-called 2-phase / 3-phase conversion.

[0048] The control signal generation unit 17 generates a control signal for the inverter 2 based on the three-phase voltage commands V u *, V v *, V w * from the 2-phase / 3-phase conversion unit 11 and a DC voltage detection signal from the DC voltage detector 50 ( Fig. 1) and outputs this control signal to the inverter 2. The control signal generation unit 17 is, for example, a PWM controller and generates the control signal for the inverter 2 using a known method. <Startsteuerung aus dem Freilaufzustand>

[0049] Next, the operation of each functional block during the transition from a freewheeling state to a normal operating state (start-up control) is described. The description of the start-up control focuses primarily on differences compared to the normal operating control, omitting the description of the control mechanisms common to the normal operating control.

[0050] First, the basic principle of phase detection (estimation of rotor position and speed) during the freewheeling of the permanent magnet synchronous motor 3 is described. In the following, it is assumed that the permanent magnet synchronous motor 3 is in a freewheeling state.

[0051] If an attempt is made to restart the permanent magnet synchronous motor 3 from a free-running state without using information about rotor position and speed, starting by normal operating control can be difficult depending on the speed of the permanent magnet synchronous motor 3. Therefore, in the present embodiment, the rotor position and speed of the permanent magnet synchronous motor 3 are calculated in the free-running state and used for starting control.

[0052] Fig. Figure 3A shows an explanatory diagram illustrating the current vector when a direct current is passed through the permanent magnet synchronous motor 3. Fig. 3A flows when the permanent magnet synchronous motor 3 is not wobbling; when a DC voltage referenced to the α-axis is applied, a DC current I flows. α_DC by the permanent magnet synchronous motor 3 on the α-axis. In this case, a β-axis current i is generated. βto 0 (zero).

[0053] On the other hand, if the permanent magnet synchronous motor 3 is tumbling (in the freewheeling state), an induced voltage E is generated due to the freewheeling of the permanent magnet synchronous motor 3, and a current le generated due to the influence of this induced voltage E becomes the direct current I. α_DC added. Therefore, a current Iαβ (=I) flows in the permanent magnet synchronous motor 3 in the free-running state. α_DC + Ie), which is obtained by vectorial addition of the current le generated by the induced voltage E to the direct current I α_DC will be received.

[0054] An α-axis current i α is a current in the α-axis direction of the current Iαβ flowing through the permanent magnet synchronous motor 3. A β-axis current i ß is a current in the β-axis direction of the current Iαβ flowing through the permanent magnet synchronous motor 3. The current le is a current generated by the freewheeling of the permanent magnet synchronous motor 3.

[0055] A phase angle θ i1 The current Iαβ changes according to a rotor position and a rotational speed in the free-running state of the permanent magnet synchronous motor 3 (that is, according to a change in the current le, as in Fig. 3A). Therefore, in the present embodiment, the rotor position and the rotational speed of the permanent magnet synchronous motor 3 in the free-running state are estimated by utilizing the fact that the currents flowing through the permanent magnet synchronous motor 3 i α , i β The angle between the current Iαβ and the α-axis is subsequently referred to as a first current phase θ. i1 The first current phase θ is designated. i1 is a phase of the current Iαβ flowing through the permanent magnet synchronous motor 3.

[0056] The in Fig. The voltage command generation unit 12 shown generates α-β-axis voltage commands V α *, V β*, which are required to estimate the rotor position and speed in the free-running state of the permanent magnet synchronous motor 3. Then the voltage command generation unit 12 outputs the generated voltage commands V α *, V β * to the voltage command switching unit 10, whereby the voltage commands V α *, V β * is output to the 2-phase / 3-phase conversion unit 11 and causes a direct current I α_DC flows through the permanent magnet synchronous motor 3.

[0057] In the present embodiment, the voltage command generation unit 12 issues a voltage command to conduct a direct current I α_DC by one phase (in the present embodiment a phase corresponding to the α-axis) among a plurality of phases (three phases in the present embodiment) of the permanent magnet synchronous motor 3.

[0058] An α-axis voltage command V α* can be set to any predetermined value. For example, the α-axis voltage command V can be set to α * can be set by calculating or experimentally determining a value capable of estimating a maximum speed of the permanent magnet synchronous motor 3 assumed in the free-running state (for example, a speed assumed during the low-speed operation of the permanent magnet synchronous motor 3). A β-axis voltage command V β * is set to 0 (zero), for example.

[0059] By means of the α-axis voltage command issued by the voltage command generation unit 12 to the 2-phase / 3-phase conversion unit 11. V a * a direct current I flows α_DC on the α-axis. It should be noted that the direct current I α_DC can change over time, and an initial value for the time-varying case can be arbitrarily predetermined.

[0060] Next, the in Fig. 2 shown freewheeling condition estimation unit 14 described.

[0061] Fig. Figure 4 shows a function block diagram illustrating the processing contents of the freewheeling state estimation unit 14.

[0062] The freewheeling state estimation unit 14 calculates an estimated initial phase θ d0 as rotor position and an estimated initial velocity ω e0 as the rotational speed in the free-running state of the permanent magnet synchronous motor 3 and outputs this to the speed / phase estimation unit 13 ( Fig. 2) from. The free-running state estimation unit 14 contains 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, a free-running velocity estimation unit 26, and a free-running phase estimation unit 27. The free-running velocity estimation unit 26 and the free-running phase estimation unit 27 are hereinafter collectively referred to as the free-running velocity / phase estimation unit.

[0063] The calculation unit 24 uses one of the 3-phase / 2-phase conversion units 15 ( Fig. 2) calculated α-axis current i α and a direct current I calculated by the DC component calculation unit 23 α_DC , to obtain a current value i α_0to calculate, which is calculated by subtracting the direct current I α_DC from the α-axis current i α is obtained (for example, i α_0 = i β - I α_DC Then the calculation unit 24 gives the calculated current value i. α_0 to the second current phase calculation unit 25.

[0064] This current value i α_0 is a current that is produced by removing the influence of the applied direct current I α_DC from the α-axis current i α is obtained, and can be obtained, for example, by subtracting the direct current I α_DC from the α-axis current i α This means that the calculation unit 24 receives a current that is obtained by removing a contribution of the direct current I. α_DC is obtained from the current Iαβ flowing through the permanent magnet synchronous motor 3.

[0065] Fig. Figure 3B shows a diagram illustrating the current value i calculated by the calculation unit 24. α_0shows. The current value i α_0 is a value obtained by subtracting the direct current I α_DC from the α-axis current i α ( Fig. 3A) is obtained. As in Fig. Figure 3B shows the current value i calculated by the calculation unit 24. α_0 An α-axis component of the current le, generated due to the influence of the induced voltage E. The angle formed by the current le and the α-axis is subsequently referred to as a second current phase θ. i2 The second current phase θ is designated. i2 is a phase of the current le, which is generated due to the influence of the induced voltage E. The current le rotates around the origin of the α-β axes due to the freewheeling of the permanent magnet synchronous motor 3.

[0066] The second current phase calculation unit 25 uses the current value i calculated by the calculation unit 24. α_0and a β-axis current i calculated by the 3-phase / 2-phase conversion unit 15 β , to the second current phase θ i2 to be calculated according to the following equation (5), and gives the second current phase θ i2 to the freewheel speed estimation unit 26 and the freewheel phase estimation unit 27. [Equation 5] θi2=tan−1(iβ / iα_0)

[0067] The second current phase θ i2 is, as described above, an angle formed by the current le generated by the induced voltage E and the α-axis ( Fig. 3A, Fig. 3B).

[0068] The freewheeling velocity estimation unit 26 is a freewheeling velocity / phase estimation unit, calculating an estimated initial velocity ω e0 using the second current phase θ calculated by the second current phase calculation unit 25 i2 and gives the calculated estimated initial velocity ωe0 to the velocity / phase estimation unit 13 ( Fig. 2) and the free-running phase estimation unit 27.

[0069] The following describes a specific example of a method by which the freewheeling velocity estimation unit 26 estimates the initial velocity ω. e0 calculated. The second current phase calculation unit 25 calculates the second current phase θ. i2 repeated in a predetermined control cycle. The freewheel speed estimation unit 26 receives a difference Δθ i2 (= θi2_2 - θi2_1) between a value of the second current phase θ calculated at time t1 i2 (previous value θi2_1) and a value of the second current phase θ calculated at time t2 after time t1. i2 (current value θi2_2) and also obtains a time Δt (= t2 - t1) from time t1 to time t2 and calculates the estimated initial velocity ω e0 (= Δθ i2 / Δt) by dividing Δθ i2 through time Δt.

[0070] The freewheeling phase estimation unit 27 is a freewheeling velocity / phase estimation unit, using the second current phase θ calculated by the second current phase calculation unit 25. i2 and the estimated initial velocity ω calculated by the freewheeling velocity estimation unit 26 e0 , to estimate an initial phase θ d0 to be calculated according to the following equations (6) and (7), and gives the calculated estimated initial phase θ d0 to the velocity / phase estimation unit 13 ( Fig. 2) out. [Equation 6] Δθi=tan−1(ωe0L / R) [Equation 7] θd0=θi2+Δθi

[0071] In equation (6) Δθ i a phase difference between the second current phase θ i2and a phase of the induced voltage E, L is an inductance of windings of the permanent magnet synchronous motor 3, and R is a resistance value of the windings of the permanent magnet synchronous motor 3.

[0072] Fig. Figure 5 shows a vector diagram illustrating an induced voltage E generated in a freewheeling state of a permanent magnet synchronous motor and a current le generated due to the influence of the induced voltage E.

[0073] As described above, Δθ i a phase difference between the second current phase θ i2 and the phase of the induced voltage E. Therefore, as can be seen from Fig. 5 shows the estimated initial phase θ calculated by equation (7). d0 the phase of the induced voltage E.

[0074] The in Fig. The velocity / phase estimation unit 13 shown uses the estimated initial phase θ calculated by the freewheeling phase estimation unit 27. d0 and the estimated initial velocity ω calculated by the freewheeling velocity estimation unit 26 e0 as initial values ​​of a rotor position and a rotational speed when the permanent magnet synchronous motor 3 transitions from the free-running state to a normal operating state (i.e., when restarting from the free-running state). The speed / phase estimation unit 13 estimates the rotor position and the rotational speed of the permanent magnet synchronous motor 3 (i.e., phase information θ). d_est and estimated velocity ω est ) using these initial values ​​and a known procedure.

[0075] Back to the description of Fig. 4.

[0076] The first current phase calculation unit 18 uses an α-axis current i α and a β-axis current i β, which is from the 3-phase / 2-phase conversion unit 15 ( Fig. 2) were calculated to determine a first current phase θ i1 to be calculated according to the following equation (8), and gives the calculated first current phase θ i1 to the absolute value calculation unit 19. This first current phase θ i1 is as in Fig. Figure 3A shows the angle between the current Iαβ flowing through the permanent magnet synchronous motor 3 and the α-axis, and represents the phase of the current Iαβ. [Equation 8] θi1=tan−1(iβ / iα)

[0077] The absolute value calculation unit 19 calculates the absolute value |θ i1 | the first current phase θ calculated by the first current phase calculation unit 18 i1 and gives this absolute value |θ i1 | to the cosine component calculation unit 22 and the maximum value recognition unit 21.

[0078] The current amplitude calculation unit 20 uses the α-axis current i α and the β-axis current i β , which is from the 3-phase / 2-phase conversion unit 15 ( Fig. 2) were calculated to determine an amount i amp to calculate the current Iαβ flowing through the permanent magnet synchronous motor 3 according to the following equation (9). [Equation 9] iamp=iα2+iβ2

[0079] The current amplitude calculation unit 20 gives the calculated amount i amp of the current Iαβ to the DC component calculation unit 23.

[0080] The cosine component calculation unit 22 calculates a cosine component cos(|θ). i1 |) of the absolute value calculated by the absolute value calculation unit 19 |θ i1 | and gives the calculated cosine component cos(|θ) i1 |) to the DC component calculation unit 23.

[0081] The maximum value detection unit 21 detects whether the absolute value |θ calculated by the absolute value calculation unit 19 i1 | has reached a maximum value, and generates a maximum value detection flag F_theta_max. When the maximum value detection unit 21 detects that the absolute value |θ i1 When the maximum value has been reached, 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 recognize that the absolute value |θ i1 | when the maximum value has been reached, it sets the maximum value detection flag F_theta_max to Off (F_theta_max=0).

[0082] For example, the maximum value recognition unit 21 determines that the maximum value of the absolute value |θ i1 | was detected, and sets the maximum value detection flag F_theta_max to On (F_theta_max=1) if all of the following conditions 1 and 2 are met. Condition 1: Δθi1_(n) is 0 (zero) or less Condition 2: Δθi1_(nk) is greater than 0 (zero) Δθi1_(n) is a rate of change over time of the absolute value |θ i1 | at an nth sampling. Δθi1_(nk) is a rate of change of the absolute value |θ over time. i1 | at a (nk)th sampling, that is, a sampling k samples before the nth sampling.

[0083] Δθi1_(n) can be obtained, for example, as follows. The absolute value calculation unit 19 is repeatedly given the absolute value |θ i1 | of the first current phase θ i1 in a predetermined control cycle. The maximum value detection unit 21 receives a difference Δθ. i1 (= |θi1|_2 - |θi1|_1) between the absolute value |θ calculated at time t3 i1 | (previous value |θi1|_1) and the absolute value |θ calculated at time t4 after time t3 i1| (current value |θi1|2) and also obtains a time Δt' (= t4 - t3) from time t3 to time t4 and calculates Δθi1(n) (= Δθi1 / Δt') by dividing Δθ i1 through time Δt'.

[0084] The absolute value calculation unit 19 stores the calculated Δθi1_(n) in a storage unit of the motor control device 4.

[0085] Since Δθi1_(nk) is a rate of change of the absolute value |θ over time i1 | at the (nk)th sampling, it can be obtained from values ​​stored in the memory unit. A value of k is set to a value where the maximum value of the absolute value |θ i1 | can be detected, and is determined in advance by calculation or experiment.

[0086] If condition 1 is satisfied, that is, if Δθi1_(n) is 0 or less, this means that the absolute value |θ i1| decreases on the nth sampling. On the other hand, if Δθi1_(n) is greater than 0, this means that the absolute value |θ i1 | increases with the nth sampling.

[0087] If condition 2 is satisfied, that is, if Δθi1_(nk) is greater than 0, this means that the absolute value |θ i1 | increased during the (nk)th sampling. On the other hand, if Δθi1_(nk) is 0 or less, this means that the absolute value |θ i1 | decreased during the (nk)th sampling.

[0088] Therefore, if both condition 1 and condition 2 are satisfied, this means that the absolute value |θ i1 | at a time point between a time point at the (nk)th sampling and a time point at the nth sampling, has changed from increasing to decreasing. The maximum value detection unit 21 can thus recognize that the absolute value |θ i1 | has reached its maximum value.

[0089] The DC component calculation unit 23 uses the amount i calculated by the current amplitude calculation unit 20. amp of the current Iαβ, the cosine component cos(|θ) calculated by the cosine component calculation unit 22. i1 |) of the absolute value |θ i1 | and the maximum value detection flag F_theta_max set by the maximum value detection unit 21 to determine a direct current I α_DC to be calculated according to equation (10) if the following condition 3 is satisfied. The DC component calculation unit 23 gives the calculated DC current I α_DC to the calculation unit 24.

[0090] Condition 3: Maximum value detection flag F_theta_max is On [Equation 10] Iα_DC=iamp / cos(|θi|)

[0091] The principle according to which direct current I α_DC obtained by equation (10) is referred to Fig. 6A and Fig. 6B described.

[0092] Fig. 6A and Fig. 6B shows explanatory diagrams that depict a current vector when a magnitude (|θ) i1 |) of the first current phase θ i1 The maximum is reached when a direct current is passed through the permanent magnet synchronous motor 3. Fig. 6A shows a current vector when the absolute value |θ i1 | is maximal when a β-axis current i β is positive. Fig. Figure 6B shows a current vector when the absolute value |θ i1 | is maximal when a β-axis current i β is negative.

[0093] As in Fig. 6A and Fig. 6B shows that when the absolute value |θ i1| its maximum is reached when the current Iαβ flowing through the permanent magnet synchronous motor 3 is tangential to the vector locus of the current le, which is generated due to the influence of the induced voltage E. At this point, the angle formed by the current le and the current Iαβ is a right angle. Therefore, as in Fig. 6A and Fig. 6B shows the direct current I α_DC using the amount i amp of the current Iαβ and the maximum value of the absolute value |θ i1 | can be obtained based on equation (10).

[0094] When calculating the direct current I α_DC are the amount i amp of the current Iαβ and the cosine component cos(|θ) i1 |) of the absolute value |θ i1 | the values ​​at the moment the maximum value detection flag F_theta_max changes from Off to On. A memory unit of the motor control device 4 stores the values ​​of i amp and cos(|θ i1|) at this time.

[0095] As also from Fig. 6A and Fig. As can be seen in 6B, there are two points in time at which the absolute value |θ i1 | reaches its maximum while the current le generated due to the influence of the induced voltage E completes one revolution. This means that there are two points in time at which the direct current I α_DC during one cycle of the current le. That is, in the present embodiment, the direct current I can be obtained α_DC to be obtained and the estimated initial phase θ d0 and the estimated initial velocity ω e0 can be calculated in a time shorter than one cycle of the current le. Therefore, in the present embodiment, compared to a conventional technique where the direct current I α_DC for example, from an average value of a maximum value and a minimum value of an α-axis current i αA rotor position (estimated initial phase θ) is obtained. d0 ) and a rotational speed (estimated initial velocity ω) e0 ) in the free-running state of the permanent magnet synchronous motor 3 can be calculated in a short time.

[0096] The processing content performed by the maximum value recognition unit 21 and the DC component calculation unit 23 for calculating the DC current I α_DC will be with reference to Fig. 7 and Fig. 8 described. Fig. Figure 7 shows an example of a flowchart illustrating a processing sequence for setting the maximum value detection flag F_theta_max. Fig. Figure 8 shows an example of a flowchart illustrating a processing sequence for calculating the direct current I. α_DC shows.

[0097] The in Fig. 8 shown processing sequence for calculating the direct current I α_DCThis process is executed when the start control is performed, and is started, for example, when the voltage command switching unit 10 switches a switching signal SW_signal from On to Off (SW_signal=0). Furthermore, this processing sequence is used to calculate the DC current I. α_DC This is executed repeatedly in a predetermined control cycle after the maximum value detection unit 21 has performed an initial setting. During this initial setting, the maximum value detection flag F_theta_max is set to Off.

[0098] The processing of the in Fig. 7 and Fig. The flowcharts shown in the 8 diagrams are based on calculation results (for example, an absolute value |θ). i1 | of the first current phase, a rate of change over time Δθi1_(n) of the absolute value |θ i1 |, a cosine component cos(|θi1|) of the absolute value |θ i1 |, an amount i ampof the current Iαβ) of each calculation unit of the free-running state estimation unit 14, which are repeatedly obtained in a predetermined control cycle.

[0099] As in Fig. As shown in Figure 8, the maximum value detection unit 21 performs a setting process for the maximum value detection flag F_theta_max in step S100.

[0100] Here, the setting process for the maximum value detection flag F_theta_max, executed by the maximum value detection unit 21, is described with reference to Fig. 7 described.

[0101] As in Fig. As shown in Figure 7, when the setting process for the maximum value detection flag F_theta_max is started, the maximum value detection unit 21 calculates a rate of change Δθi1_(n) of the absolute value |θ over time in step S110. i1 | during an nth sampling and stores the calculated Δθi1_(n) in a storage unit of the motor control device 4.

[0102] In step S120, the maximum value detection unit 21 determines whether the Δθi1_(n) calculated in step S110 is 0 (zero) or less (that is, whether condition 1 is satisfied). If Δθi1_(n) is 0 or less, the process proceeds to step S130. If Δθi1_(n) is greater than 0, the process proceeds to step S150.

[0103] In step S130, the maximum value detection unit 21 determines whether a time rate of change Δθi1_(nk) of the absolute value |θ i1 | on an (nk)th sample, calculated in step S110 and stored in the memory unit of the motor control device 4, is greater than 0 (zero) (that is, whether condition 2 is satisfied). If Δ0i1_(nk) is greater than 0, the process proceeds to step S140. If Δθi1_(nk) is 0 or less, the process proceeds to step S150.

[0104] In step S140, the maximum value detection unit 21 sets the maximum value detection flag F_theta_max to On (F_theta_max=1) and ends the Fig. 7 shown setting process for the maximum value detection flag F_theta_max.

[0105] In step S150, the maximum value detection unit 21 sets the maximum value detection flag F_theta_max to Off (F_theta_max=0) and terminates the process. Fig. 7 shown setting process for the maximum value detection flag F_theta_max.

[0106] If the in Fig. When the setting process shown in step 7 for the maximum value detection flag F_theta_max ends, the process continues from step S210 in Fig. 8 executed. The processes after step S210 in Fig. 8 are executed by the DC component calculation unit 23.

[0107] In step S210 of Fig. Step 8 determines whether the maximum value detection flag F_theta_max is on (i.e., whether condition 3 is met) for the DC component calculation unit 23. If the current setting of the maximum value detection flag F_theta_max is on, the process proceeds to step S220. If the current setting of the maximum value detection flag F_theta_max is off, the process proceeds to step S100, and the setting process for the maximum value detection flag F_theta_max ( Fig. 7) is executed.

[0108] In step S220, the DC component calculation unit 23 holds the values ​​of the cosine component cos(|θ). i1 |) of the absolute value |θ i1 | and the amount i amp of the current Iαβ at the time the maximum value detection flag F_theta_max switches from off to on. Then the DC component calculation unit 23 stores the held values ​​of cos(|θ). i1 |) and i ampin a storage unit of the motor control device 4.

[0109] In step S230, the DC component calculation unit 23 uses the cosine component cos(|θ) held in step S220. i1 |) of the absolute value |θ i1 | and the amount i amp of the current Iαβ, in order to generate a direct current I α_DC to calculate based on equation (10). Then the DC component calculation unit 23 stores the calculated DC current I. α_DC in the storage unit of the engine control device 4 and terminates the processing of the in Fig. 8 flowchart shown in the current tax cycle.

[0110] The DC component calculation unit 23 outputs the DC current I calculated in step S230. α_DC to the calculation unit 24 ( Fig. 4) out. The DC component calculation unit 23 holds the calculated DC current I α_DC, until the switching signal SW_signal switches from Off to On (i.e., during the transition from the freewheeling state to the normal operating state), and outputs it to the calculation unit 24.

[0111] In this way, when the maximum value detection flag F_theta_max is switched from Off to On, it is recognized that the absolute value |θ i1 | has reached its maximum value, the direct current I α_DC based on the amount i amp of the current Iαβ and the cosine component cos(|θ) i1 |) of the absolute value |θ i1 | calculated at the time when the absolute value |θ i1 | reached the maximum value.

[0112] The following will refer to Fig. 9 An example of the operation and advantageous effects of the motor control device 4 according to the present embodiment in a freewheeling state in which the rotor of the permanent magnet synchronous motor 3 is spinning is described.

[0113] Fig. Figure 9 shows a diagram illustrating the temporal changes of each parameter calculated by the motor control device 4 according to the present embodiment (an α-axis current i). α , a β-axis current i β , a current value i calculated by the calculation unit 24 α_0 , an absolute value |θ i1 | of the first current phase, a direct current I α_DC , a second current phase θ i2 and an estimated initial phase θ d0 ) and the induced voltage phase θ d of the permanent magnet synchronous motor 3.

[0114] The advantageous effects of the present embodiment are illustrated below by comparing the motor control device 4 according to the present embodiment with a motor control device of a comparative example. The motor control device in the comparative example is a conventional motor control device and calculates the direct current I. α_DCfrom an average value of a maximum value and a minimum value of the α-axis current i α It should be noted that the operation of the permanent magnet synchronous motor 3 is assumed to be the same in the present embodiment and in the comparative example.

[0115] The motor control device in the comparison example performs the calculation of the direct current I. α_DC according to the following procedure 1 and procedure 2 instead of the above conditions 1 to 3 and equation (10). Method 1: Recording a maximum value i α_max and a minimum value i α_min of the α-axis current and holding it in a storage unit of the motor control device. Method 2: If both the maximum value i α_max as well as the minimum value i α_min of the α-axis current recorded in method 1, using the values ​​of the maximum value i α_max and the minimum value i α_minof the α-axis current, which are held by the storage unit to generate the direct current I α_DC to calculate based on, for example, equation (11). [Equation 11] Iα_DC=(iα_max+iα_min) / 2

[0116] Equation (11) calculates the direct current I α_DC from the average value of the maximum value i α_max and the minimum value i α_min of the α-axis current.

[0117] Fig. Figure 9 shows six graphs, from graph (a) to graph (f). The horizontal axes of these graphs represent time (elapsed time).

[0118] Graph (a) shows the α-axis current i α and the β-axis current i β , calculated by the 3-phase / 2-phase conversion unit 15, and the current value i calculated by the calculation unit 24 α_0 .

[0119] Graph (b) shows the absolute value |θ calculated by the absolute value calculation unit 19. i1| of the first power phase.

[0120] Graph (c) shows the direct current I calculated by the DC component calculation unit 23 in the present embodiment. α_DC and the direct current I calculated by methods 1 and 2 in the comparative example α_DC .

[0121] Graph (d) shows the second current phase θ calculated by the second current phase calculation unit 25. i2 .

[0122] Graph (e) shows the induced voltage phase θ d the permanent magnet synchronous motor 3.

[0123] Graph (f) shows the estimated initial phase θ calculated by the free-running phase estimation unit 27. d0 .

[0124] Fig. Figure 9 shows changes in timing after the permanent magnet synchronous motor 3 is in free-running mode and the switching signal SW_signal has switched from On to Off.

[0125] Time t0 is a time at which the flowchart of Fig. 8 shown processing (processing for calculating the direct current I) α_DC ) is started.

[0126] Time t1 is a time at which the maximum value detection unit 21 recognizes that the absolute value |θ i1 | the first current phase has reached its maximum value, and the maximum value detection flag F_theta_max switches from Off to On.

[0127] Time t2 is a time at which the motor control device in the comparison example reaches the minimum value i. α_min of the α_axis current i α recorded and the minimum value i α_min holds.

[0128] Time t3 is a time at which the maximum value detection unit 21 recognizes that the absolute value |θ i1 | the first current phase has again reached its maximum value.

[0129] Time t4 is a time at which the motor control device in the comparison example reaches the maximum value i. α_max of the α-axis current i α recorded and the maximum value i α_max holds.

[0130] As shown in graph (a), in the present 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 has the DC current I α_DC not calculated, so the α-axis current i α and the current value i calculated by the calculation unit 24 α_0 are identical. 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 i. α_0 based on the direct current I calculated by the DC component calculation unit 23 α_DC and the α-axis current i α The current value iα_0 is a value obtained by subtracting the direct current I α_DC from the α-axis current i α will be received.

[0131] On the other hand, in the case of the comparison example, procedure 1 is executed at time t2, the minimum value i α_min of the α-axis current i α is recorded, and the minimum value i α_min is held. Then procedure 1 is executed at time t4, the maximum value i. α_max of the α-axis current i α is recorded, and the maximum value i α_max will be held.

[0132] As shown in graph (b), in the present embodiment the absolute value |θ i1 | of the first current phase from time to time t1 and reaches its maximum value at time t1. The absolute value |θ i1 The first current phase decreases from time t1 to time t2 and increases again from time t2 to time t3. Then the absolute value |θ reaches i1The absolute value |θ of the first current phase reaches its maximum value again at time t3 and decreases again from time t3 to time t4. After time t4, the absolute value |θ repeats. i1 | the changes described above during the first power phase.

[0133] As shown in graph (c), in the present embodiment the maximum value detection flag F_theta_max is off and the direct current I is off from time t0 to time t1. α_DC is not calculated, so the direct current I α_DC Null is. At time t1, the direct current I α_DC calculated, since the absolute value |θ i1 | the first current phase has reached its maximum value, and the calculated direct current I α_DC will be held.

[0134] On the other hand, in the case of the comparison example, the minimum value i is α_min of the α-axis current i α recorded at time t2, and the maximum value i α_max of the (X-axis current i αis recorded at time t4, so that the direct current I α_DC is calculated at time t4.

[0135] That means the direct current I α_DC In the present embodiment, it is calculated at time t1, and in the comparative example at time t4. Therefore, in the present embodiment, the direct current I can be α_DC calculated at an earlier time than in the comparison example, that is, by a time (time t4 - time t1) earlier than in the comparison example, and a rotor position (estimated initial phase θ) d0 ) and a rotational speed (estimated initial velocity ω) e0 ) in the free-running state of the permanent magnet synchronous motor 3 can be calculated in a short time.

[0136] As shown in graph (d), in the present embodiment the α-axis current i is from time t0 to time t1 α and the current value i calculated by the calculation unit 24 α_0identical, so that θ i1 , calculated from the first current phase calculation unit 18, and the second current phase θ i2 , calculated by the second current phase calculation unit 25, are also identical. At time t1, since the direct current I α_DC The current value i calculated by the calculation unit 24 is calculated. α_0 to a value obtained by subtracting the direct current I α_DC from the α-axis current i α is obtained. Therefore, the second current phase calculation unit 25 calculates the second current phase θ after time t1. i2 The second current phase θ i2 is an angle formed by a current le generated due to the induced voltage E and the α-axis ( Fig. 3A, Fig. 3B). Graph (e) shows an example of the time change of the induced voltage phase θ. dof the permanent magnet synchronous motor 3 in the present embodiment, that is, an angle formed by the induced voltage E generated by rotation of the rotor of the permanent magnet synchronous motor 3 and the α-axis (phase of the induced voltage E).

[0137] As shown in graph (f), in the present embodiment, from time t0 to time t1, as described above, the second current phase θ calculated by the second current phase calculation unit 25 is correct. i2 with θ i1 This corresponds to the value calculated by the first current phase calculation unit 18. Therefore, the value obtained by adding the phase difference Δθ i (calculated by equation (6)) between the second current phase θ i2 and the phase of the induced voltage E to the first current phase θ i1 is obtained as the estimated initial phase θ d0calculated. After time t1, since a value calculated by the second current phase calculation unit 25 is used for the second current phase θ i2 becomes ( Fig. 3A, Fig. 3B), which is an angle formed by the current le generated due to the influence of the induced voltage E and the α-axis, the estimated initial phase θ d0 , which is an estimated value of the induced voltage phase θ d is calculated by equation (7).

[0138] The effects of the motor control device 4 according to the present embodiment are described.

[0139] In a conventional motor control device, the short-circuit current flowing through the motor windings during short-circuit operation of an inverter is determined by the induced voltage of the motor and the resistance and inductance of the windings. Therefore, depending on the freewheeling speed during short-circuit operation, an overcurrent can occur. Furthermore, because a special PWM control mode and special current sensing processing are used, which involves detecting a bus current flowing through a shunt resistor, calculations to determine the rotor position and speed of a motor become complex, and errors in the estimation results are likely.

[0140] In contrast, in the motor control device 4 according to the present embodiment, the freewheeling state estimation unit 14 calculates a first current phase θ i1, which is a phase of a current Iαβ flowing through the permanent magnet synchronous motor 3 in the free-running state, and uses an amount i amp of the current Iαβ and an amount of the first current phase θ i1 at the time when the magnitude of the first current phase θ i1 maximum is to generate a direct current I α_DC to calculate, and uses the direct current I α_DC and the current Iαβ to create a second current phase θ i2 to calculate which is one phase of a current le generated by freewheeling the permanent magnet synchronous motor 3, and uses the second current phase θ i2 , to determine a rotor position and rotational speed (an estimated initial phase θ) d0 and an estimated initial velocity ω e0The motor control device 4 according to the present embodiment has such a configuration and calculates the rotor position and speed of the permanent magnet synchronous motor 3 by a simple calculation with a lower incidence of errors without the use of a position detector, so that the rotor position and speed of the permanent magnet synchronous motor 3 can be calculated with higher accuracy and in a shorter time.

[0141] It should be noted that the present invention is not limited to the embodiment described above and various modifications are possible. For example, the embodiment described above has been described in detail to explain the present invention in an easily understandable manner, and the present invention is not necessarily limited to an aspect that includes all the described configurations. Furthermore, a part of a configuration of one embodiment can be replaced by a configuration of another embodiment. Furthermore, a configuration of another embodiment can be added to a configuration of one embodiment. Furthermore, with respect to a part of a configuration of each embodiment, it is possible to delete or add / replace another configuration.

[0142] Furthermore, each configuration of the motor control device 4 according to the present invention can be implemented in hardware, for example by designing some or all of them with an integrated circuit or the like. Alternatively, some or all of them can be implemented in software by having a processor interpret and execute a program that implements each function. Information such as a program, a table, a file, measurement information, and calculation information that implements each function can be recorded in a recording device such as a memory, a hard disk drive or an SSD (solid-state drive), or a recording medium such as an IC card, an SD card, or a DVD. Therefore, each configuration of the control device according to the present invention can implement each function as a processing unit, a processing module, a program module, or the like. Reference symbol list 1 DC power supply 2 inverters 3 permanent magnet synchronous motor 4 Motor control device 5 shunt resistance 6 amplifiers 7 Speed ​​control unit 8 d-axis current command generation unit 9 Power control unit 10 Voltage command switching unit 11 2-phase / 3-phase conversion unit 12 Voltage command generation unit 13 Velocity / Phase Estimation Unit 14 Freewheel condition estimation unit 15 3-phase / 2-phase conversion unit 16 Current reconstruction 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 recognition unit 22 cosine component calculation unit 23 DC component calculation unit 24 units of calculation 25 Second current phase calculation unit 26 Freewheel speed estimation unit 27 Freewheel phase estimation unit 35 units of calculation 50 DC voltage detector QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2015-73361

[0006] JP 2018-170928

[0006]

Claims

[1] Motor control device configured to control the operation of a permanent magnet synchronous motor by controlling an inverter that supplies alternating current power to the permanent magnet synchronous motor, the motor control device comprising: a voltage command generation unit that outputs a voltage command to pass a direct current through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in a free-running condition; a free-running state estimation unit that calculates the rotor position and speed of the permanent magnet synchronous motor in the free-running state; and a speed / phase estimation unit which estimates the rotor position and speed of the permanent magnet synchronous motor using the rotor position and speed calculated by the freewheeling state estimation unit as initial values; wherein, In the permanent magnet synchronous motor, a current flows in the freewheeling state, which is obtained by adding a current generated by the freewheeling of the permanent magnet synchronous motor to the direct current. The freewheel condition estimation unit contains: a first current phase calculation unit that calculates a first current phase, which is a phase of the current flowing through the permanent magnet synchronous motor in the free-running state; a DC component calculation unit that calculates the DC current using an amount of current and an amount of the first current phase at the time when the amount of the first current phase is at its maximum; a second current-phase calculation unit, which calculates a second current phase, which is a phase of the current generated by the freewheeling of the permanent magnet synchronous motor, using the direct current and the current; and a freewheeling speed / phase estimation unit that calculates the rotor position and speed of the permanent magnet synchronous motor in the freewheeling state using the second current phase. [2] Motor control device according to claim 1, wherein the second current phase calculation unit calculates the second current phase using a current value obtained by subtracting the direct current from the current. [3] Motor control device according to claim 1, wherein The permanent magnet synchronous motor is a motor with a multitude of phases, and The voltage command generation unit issues the voltage command to apply direct current to one phase among the multitude of phases of the permanent magnet synchronous motor. [4] Motor control device according to claim 1, wherein A current flowing through the permanent magnet synchronous motor in freewheeling condition is expressed by 3-phase / 2-phase conversion as an α-axis current (a current in the α-axis direction) and a β-axis current (a current in the β-axis direction), and The first current phase calculation unit calculates the first current phase using the α-axis current and the β-axis current. [5] Motor control device according to claim 4, wherein the first current phase is the angle between the current and the α-axis. [6] Motor control device according to claim 4, wherein the second current phase is the angle between a current generated by the freewheeling of the permanent magnet synchronous motor and the α-axis. [7] Motor control device according to claim 4, wherein the second current phase calculation unit calculates the second current phase using a current value obtained by subtracting the DC current from the α-axis current. [8] Motor control method for controlling the operation of a permanent magnet synchronous motor by controlling an inverter which supplies alternating current power to the permanent magnet synchronous motor, comprising: a voltage command generation step to output a voltage command to pass a direct current through the permanent magnet synchronous motor when the permanent magnet synchronous motor is in a free-running condition; a free-running state estimation step for calculating the rotor position and speed of the permanent magnet synchronous motor in the free-running state; and a velocity / phase estimation step for estimating the rotor position and speed of the permanent magnet synchronous motor using the rotor position and speed calculated in the freewheeling state estimation step as initial values; wherein, In the permanent magnet synchronous motor, a current flows in the freewheeling state, which is obtained by adding a current generated by the freewheeling of the permanent magnet synchronous motor to the direct current. The freewheeling state estimation step includes: a first current phase calculation step to calculate a first current phase, which is a phase of the current flowing through the permanent magnet synchronous motor in the free-running state; a DC component calculation step to calculate the DC current using a current magnitude and a first current phase magnitude at the time when the first current phase magnitude is at its maximum; a second current phase calculation step for calculating a second current phase, which is a phase of the current generated by the freewheeling of the permanent magnet synchronous motor, using the direct current and the current; and a freewheeling speed / phase estimation step to calculate the rotor position and speed of the permanent magnet synchronous motor in the freewheeling state using the second current phase.

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