CN116349128A

CN116349128A - Motor control device, and washing machine or washing dryer equipped with same

Info

Publication number: CN116349128A
Application number: CN202180072186.XA
Authority: CN
Inventors: 孙昊; 龟田晃史; 上泷祯士; 藤冈裕智; 贺门阳子
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2020-10-26
Filing date: 2021-10-04
Publication date: 2023-06-27
Also published as: JP7442052B2; JPWO2022091701A1; WO2022091701A1; TW202232879A

Abstract

A motor control device (10) controls a brushless motor (40) having a rotor with a salient pole structure, which is driven by an inverter circuit (13). A motor control device (10) is provided with an inverter circuit (13), a current detection unit (21), an initial phase estimation unit (22), and a polarity determination unit (23). An initial phase estimation unit (22) estimates the initial phase of the brushless motor (40) based on the current detected by the current detection unit (21). A polarity determination unit (23) determines the polarity of the magnetic pole of the brushless motor (40) on the basis of the current amplitude difference between the positive and negative directions of the d-axis and q-axis detected by the current detection unit (21) after superimposing the voltages in the positive and negative directions of the d-axis and q-axis with respect to the initial phase estimated by the initial phase estimation unit (22), and corrects the initial phase.

Description

Motor control device, and washing machine or washing dryer equipped with same

Technical Field

The present disclosure relates to a motor control device that performs sensorless control of rotation of a brushless motor (permanent magnet synchronous motor) having a rotor with a salient pole structure, and a washing machine or a washing dryer equipped with the motor control device.

Background

Patent document 1 discloses a motor control device that performs sensorless driving of a brushless motor having a salient pole structure as a rotor and performs pole determination at the time of start-up. The motor control device converts direct-current power into alternating-current power and drives a brushless motor having a rotor with a salient pole structure with the alternating-current power as motor power. The motor control device includes a current detector, a three-phase-dq-axis conversion unit, a dq-axis current control unit, a dq-axis-three-phase conversion unit, an alternating current alternating voltage generation unit for estimating a magnetic pole position, a magnetic pole position estimation unit, a d-axis current DC offset generation unit, and an NS determination unit. The current detector detects a motor current from the inverter to the brushless motor. The three-phase-dq-axis conversion unit performs dq-axis conversion on the ac current detection value detected by the current detector to output a d-axis current detection value and a q-axis current detection value. The dq-axis current control unit calculates a d-axis voltage command and a q-axis voltage command such that the d-axis current detection value and the q-axis current detection value follow the d-axis current command input and the q-axis current command input. The dq-axis/three-phase conversion unit converts the d-axis voltage command and the q-axis voltage command into three-phase ac voltage commands, and supplies the three-phase ac voltage commands obtained by the conversion to the inverter as control signals. The alternating-current voltage generating unit for estimating the magnetic pole position superimposes an auxiliary alternating-current voltage on the d-axis voltage command. A magnetic pole position estimating unit estimates the magnetic pole position of the permanent magnet synchronous motor based on the q-axis current detection value and the auxiliary alternating voltage. The d-axis current DC bias generation unit adds a d-axis DC bias current of a fixed waveform, which alternately switches positive and negative symmetrically, to the d-axis current command with the direction of the magnetic pole position estimated by the magnetic pole position estimation unit as the d-axis, and inputs the d-axis current command to the dq-axis current control unit. The NS determination unit estimates the d-axis applied voltage and the d-axis current change rate at the positive and negative switching timings of the d-axis DC bias current, determines the direction of the N pole and the S pole of the permanent magnet synchronous motor based on the relationship between the estimated d-axis applied voltage and the d-axis current change rate, and outputs an NS determination signal.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2008-79489

Disclosure of Invention

Problems to be solved by the invention

The present disclosure provides a motor control device capable of accurately detecting magnetic poles even when the direction of d-axis obtained by initial estimation deviates from the correct direction by 90 DEG or 270 DEG, and a washing machine or a washing dryer equipped with the motor control device.

The motor control device in the present disclosure controls a brushless motor having a rotor of salient pole configuration driven by an inverter circuit. The motor control device in the present disclosure is provided with an inverter circuit, a current detection unit, an initial phase estimation unit, and a polarity determination unit. The current detection unit detects a current of the brushless motor. The initial phase estimating unit estimates an initial phase of the brushless motor based on the current detected by the current detecting unit. The polarity determination unit determines the polarity of the magnetic pole of the brushless motor based on the current detected by the current detection unit. The polarity determination unit determines the polarity of the magnetic pole of the brushless motor based on the current amplitude difference between the positive and negative directions of the d-axis and q-axis detected by the current detection unit after the voltage is superimposed on the positive and negative directions of the d-axis and q-axis, respectively, with respect to the initial phase estimated by the initial phase estimation unit, and corrects the initial phase.

In addition, the washing machine or the washing dryer in the present disclosure is mounted with the motor control device in the present disclosure.

The motor control device in the present disclosure can accurately perform magnetic pole detection even when the direction of the d-axis obtained by performing initial estimation is deviated from the correct direction by 90 ° or 270 °.

In addition, since the washing machine or the washing dryer of the present disclosure is equipped with the motor control device of the present disclosure as described above, for example, the washing tub, the drum, and the like can be smoothly rotated.

Drawings

Fig. 1 is a diagram showing a configuration of a motor control device in embodiment 1.

Fig. 2 is a block diagram showing the structure of a sensorless estimation unit of the motor control device in embodiment 1.

Fig. 3 is a block diagram showing a detailed configuration of an inductance driving unit of the motor control device in embodiment 1.

Fig. 4 is a block diagram showing a detailed configuration of an induced voltage driving section of the motor control device in embodiment 1.

Fig. 5 is a flowchart showing a flow of motor drive control processing of the motor control device in embodiment 1.

Fig. 6A is a diagram for explaining a problem related to initial phase estimation of the rotor.

Fig. 6B is a diagram for explaining a problem related to initial phase estimation of the rotor.

Fig. 6C is a diagram for explaining a problem related to initial phase estimation of the rotor.

Fig. 7 is a graph showing the magnetic saturation characteristics of an electromagnetic steel sheet used in a general brushless motor.

Fig. 8 is a flowchart showing a flow of polarity determination processing of the motor control device in embodiment 1.

Fig. 9 is a diagram showing an example of applied voltage and current at the time of d-axis determination in the motor control device according to embodiment 1.

Fig. 10 is a diagram showing an example of applied voltage and current at the time of d-axis and q-axis determination in the motor control device according to embodiment 1.

Fig. 11 is a diagram for explaining the applied voltage and current at the time of offset correction at the time of polarity discrimination in the motor control device in embodiment 1.

Fig. 12 is a diagram for explaining an outline of polarity discrimination in the case where current control is performed in the motor control device in embodiment 2.

Detailed Description

Thus, the motor control device in the present disclosure can accurately perform magnetic pole detection even when the direction of the d-axis obtained by performing initial estimation is deviated from the correct direction by 90 ° or 270 °. Therefore, the motor control device in the present disclosure can suppress the reverse start and the start failure at the time of starting the brushless motor, and smoothly accelerate from the time of starting the brushless motor.

In the motor control device according to the present disclosure, the polarity determination unit may terminate the polarity determination of the brushless motor when an absolute value of a current amplitude difference between the positive direction and the negative direction of the d-axis detected by the current detection unit after the voltage is superimposed on the positive direction and the negative direction of the d-axis is greater than a reference value. When the absolute value of the current amplitude difference between the positive and negative directions of the d-axis is smaller than the reference value, the polarity determination unit performs the following processing. That is, the polarity determination unit may determine the polarity of the magnetic pole of the brushless motor based on the current amplitude difference between the positive direction and the negative direction of the q-axis and the current amplitude difference between the positive direction and the negative direction of the d-axis detected by the current detection unit after the voltage is superimposed on the positive direction and the negative direction of the q-axis, and correct the initial phase.

In the motor control device according to the present disclosure, the polarity determination unit may set the current detected by the current detection unit immediately before the voltage is superimposed in the positive and negative directions of the d-axis and the q-axis as the offset current value. The polarity determination unit may determine the polarity of the magnetic pole of the brushless motor based on a value obtained by subtracting the offset current value from the maximum value of the current amplitudes in the positive and negative directions of the d-axis and q-axis detected by the current detection unit after the voltages are superimposed in the positive and negative directions of the d-axis and q-axis, and correct the initial phase.

In the motor control device according to the present disclosure, the polarity determination unit may control the current flowing to the brushless motor to be 0 during the period in which the polarity of the magnetic pole of the brushless motor is determined.

(insight underlying the present disclosure, etc.)

As the inventors have conceived the present disclosure, a technique of determining the polarity of a magnetic pole with respect to an estimated initial phase of a rotor is known. The initial phase of the rotor is estimated at the time of sensorless driving of the brushless motor of the salient pole configuration, at the time of starting the brushless motor driving, and at the time of stopping the brushless motor before driving.

In the initial phase estimation, the difference between the inductance L in the direction of the magnetic pole (d-axis direction) which is a characteristic of the rotor having saliency and the inductance L in the direction orthogonal to the magnetic pole (q-axis direction) is used. In the initial phase estimation, a low-amplitude high-frequency or pulse-like voltage and current are applied to the stator winding to estimate in which direction the rotor is oriented. At most, the direction of the rotor can be estimated at this time point, but the polarity (NS) of the magnetic pole is not known, so that the polarity determination is performed to determine the N-pole and S-pole of the magnetic pole.

In the polarity determination, a pulse-like voltage and current, which are large to some extent in both the positive and negative directions of the estimated d-axis direction, are applied to the stator winding, and the direction of the magnetic pole NS is estimated based on the difference between the absolute values of the applied voltage and the detected current at that time. Accordingly, the rotation of the brushless motor can be smoothly started without occurrence of reverse driving or failure in starting from the start of driving the brushless motor.

However, the following occurs at a certain rate: the direction of the d-axis estimated at the time of initial phase estimation should be the direction of the magnetic pole, but the estimated value is the direction (q-axis direction) orthogonal to the magnetic pole. The inventors found the following problems: in this case, since the correct rotor direction cannot be obtained even when the polarity determination is performed, there are cases where the phenomenon such as reverse driving and out-of-step without rotation occurs at the start of driving the brushless motor, and the subject of the present disclosure is conceived to solve the problem.

Accordingly, the present disclosure provides a motor control device capable of accurately performing magnetic pole detection in polarity determination even if the d-axis direction estimated at the time of initial phase estimation deviates from the correct direction by 90 ° or 270 °.

Embodiments in the present disclosure will be described in detail below with reference to the accompanying drawings. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters or repeated descriptions of substantially the same structure may be omitted. This is to avoid that the following description becomes too lengthy to be easily understood by a person skilled in the art.

Furthermore, the figures and the following description are provided to enable those skilled in the art to fully understand the present disclosure and are not intended to thereby limit the subject matter recited in the claims.

(embodiment 1)

The motor control device 10 in embodiment 1 will be described below with reference to fig. 1 to 11.

[1-1. Structure ]

[1-1-1. Structure of Motor control device ]

Fig. 1 is a diagram showing a configuration of a motor control device 10 in embodiment 1.

The motor control device 10 receives electric power from the ac power supply 30. The rectifier circuit 11 converts the received ac power into dc power, and supplies the power to the inverter circuit 13 via the smoothing capacitor 12 of the dc power. The inverter circuit 13 is composed of three groups of six

switching elements

14a, 14b, 14c, 14d, 14e, and 14f connected in series every two.

The inverter circuit 13 performs PWM driving of ON/OFF (ON/OFF) of the

switching elements

14a, 14b, 14c, 14d, 14e, and 14f by a control circuit 20 described later, thereby driving the brushless motor 40.

Resistors

15a, 15b, and 15c are connected to emitter sides of switching

elements

14d, 14e, and 14f, which are lower switching elements among the switching

elements

14a, 14b, 14c, 14d, 14e, and 14f connected in series with each other in the inverter circuit 13. The other ends of the

resistors

15a, 15b, and 15c are connected to one side of the output of the rectifying circuit 11 and the smoothing capacitor 12. The voltages across the

resistors

15a, 15b, and 15c are input to the current detection unit 21 in the control circuit 20. As described later, various controls are performed using the current value detected by the current detection unit 21.

The control circuit 20 includes the current detection unit 21, the initial phase estimation unit 22, the polarity determination unit 23, and the sensorless estimation unit 24. In addition, the motor control device 10 has a computer system having a processor and a memory. The computer system functions as the control circuit 20 by executing a program stored in the memory by the processor. Here, the program executed by the processor is recorded in advance in the memory of the computer system, but may be provided by being recorded in a non-transitory recording medium such as a memory card, or may be provided by a telecommunication line such as the internet.

1-1-2. Structure of sensorless estimation portion ]

Fig. 2 is a block diagram showing the structure of the sensorless estimation unit 24 of the motor control device 10 according to embodiment 1.

The sensorless estimation unit 24 includes an inductance driving unit 24b of an inductance type, an induced voltage driving unit 24c of an induced voltage type, and a driving mode switching unit 24a. The inductance driving unit 24b of the inductance type estimates the phase of the magnetic pole by using the saliency of the rotor 41 of the salient pole structure of the brushless motor 40. The induced voltage driving unit 24c of the induced voltage system estimates the magnetic pole position using the back electromotive force generated during rotation of the brushless motor 40. The drive system switching unit 24a switches the estimation system of the magnetic pole position between the inductance system and the induced voltage system.

1-1-3 Structure of inductance drive section

The inductance L varies according to the phase of the poles of the rotor 41 of the brushless motor 40. Therefore, the inductance driving unit 24b of the inductance system applies a high-frequency current independent of the motor driving current to the motor to detect the motor current, thereby calculating the position estimation error amount due to the inductance change. Then, the inductance driving section 24b estimates the magnetic pole position so that the position estimation error amount converges to zero.

Fig. 3 is a block diagram showing the detailed configuration of the inductance driving unit 24b of the motor control device 10 according to embodiment 1.

The inductance driving unit 24b is constituted by a uvw→dq current conversion unit 24ba, a position estimation Φ calculation unit 24bb, a high-frequency current control unit 24bc, an angular velocity ω calculation unit 24bd, a position angle θ calculation unit 24be, a speed current control unit 24bf, and a dq→uvw voltage conversion unit 24 bg. The uvw→dq current conversion unit 24ba receives three-phase current values (Iu, iv, iw) of the brushless motor 40 (see fig. 1) detected by the current detection unit 21 as inputs, and outputs the dq current value. The position estimation phi calculation unit 24bb performs position estimation of the magnetic pole based on the dq current, and outputs a position estimation value phi. The high-frequency current control unit 24bc controls the high-frequency current superimposed on the drive current. The angular velocity ω calculating unit 24bd calculates an angular velocity ω from the position estimation value Φ, and outputs the calculated angular velocity ω. The position angle θ calculation unit 24be calculates the position angle θ from the position estimation value Φ and the angular velocity ω, and outputs the calculated position angle θ. The speed-current control unit 24bf feeds back the deviation between the estimated angular speed (angular speed ω) and the speed command value ω, performs a speed operation (PI control), determines a current command value of the brushless motor 40, and outputs the determined current command value of the brushless motor 40. The dq→uvw voltage conversion unit 24bg calculates voltages (Vu, vv, vw) based on the position angle θ and the current command value, and outputs the calculated voltages (Vu, vv, vw) to the control circuit 20.

dq Σ≡uvw conversion and speed feedback control are general, and therefore, the description of the uvw→dq current conversion unit 24ba, the speed current control unit 24bf, and the dq→uvw voltage conversion unit 24bg is omitted here.

The position estimation Φ calculation unit 24bb calculates the position estimation value Φ based on the following expression 1.

[ number 1]

In embodiment 1, the motor to be driven is a brushless motor 40 having a rotor 41 with a salient pole structure (d-axis inductance ld++q-axis inductance Lq), and therefore the inductance L (reluctance) varies according to the phase of the magnetic poles. Since the change in inductance L is reflected in the current of the brushless motor 40, the position estimation error amount is calculated from the amount of change in the current of the brushless motor 40 based on the above equation 1.

The high-frequency current control unit 24bc controls the high-frequency current independent of the motor drive current. In embodiment 1, a pulse current corresponding to 0.4A having a period of 2.56ms is applied in the d-axis direction, and the difference between the q-axis current value when the pulse current is applied and the q-axis current value when the pulse current is not applied is calculated.

The position angle θ calculation unit 24be and the angular velocity ω calculation unit 24bd calculate the position angle θ and the angular velocity ω based on the following expression 2 and expression 3, respectively.

[ number 2]

[ number 3]

ω＝dθ/dt

The position angle θ is calculated with the time integral of the position estimation error amount and the angular velocity ω as input, and the angular velocity ω is calculated as the time derivative of the position angle θ. The position angle θ and the angular velocity ω are each calculated so that the position estimation error amount converges to zero based on feedback control.

1-1-4. Structure of induced Voltage drive section ]

The induced voltage generated by the rotation of the brushless motor 40 varies according to the magnetic pole position. Therefore, the induced voltage driving unit 24c calculates an induced voltage proportional to the speed of the brushless motor 40 based on the voltage and the current applied to the brushless motor 40, and estimates the magnetic pole position so that the voltage error converges to zero.

Fig. 4 is a block diagram showing the detailed configuration of the induced voltage driving section 24c of the motor control device 10 according to embodiment 1.

The induced voltage driving unit 24c is constituted by a uvw→dq current conversion unit 24ca, a position estimation epsilon gamma calculation unit 24cb, an angular velocity omega calculation unit 24cc, a position angle theta calculation unit 24cd, a velocity current control unit 24ce, and a dq→uvw voltage conversion unit 24 cf. The uvw→dq current conversion unit 24ca receives three-phase current values (Iu, iv, iw) of the brushless motor 40 detected by the current detection unit 21 as inputs, and outputs a dq current value. The position estimation epsilonγ arithmetic unit 24cb performs position estimation of the magnetic pole based on the dq current, and outputs a position estimation value epsilonγ. The angular velocity ω calculating unit 24cc calculates an angular velocity ω from the position estimation value εγ, and outputs the calculated angular velocity ω. The position angle θ calculation unit 24cd calculates a position angle θ from the position estimation value εγ and the angular velocity ω, and outputs the calculated position angle θ. The speed-current control unit 24ce performs a speed calculation (PI control) by feeding back a deviation between the estimated angular velocity (angular velocity ω) and the speed command value ω, determines a current command value of the motor, and outputs the determined current command value of the motor. The dq→uvw voltage conversion unit 24cf calculates voltages (Vu, vv, vw) based on the position angle θ and the current command value, and outputs the calculated voltages (Vu, vv, vw) to the control circuit 20.

Similar to the case of the inductance driving unit 24b described above, dq Σ≡uvw conversion and speed feedback control are common modes. Therefore, the description of the uvw→dq current conversion section 24ca, the speed current control section 24ce, and the dq→uvw voltage conversion section 24cf is omitted here.

The position estimation epsilon gamma operation unit 24cb calculates a position estimation value epsilon gamma based on the following expression 4.

[ number 4]

εγ＝Vd-(Ra·Id-ω·Lq·Iq)

According to equation 4, the position estimation value εγ is calculated from parameters of the q-axis inductance Lq and the resistance value Ra of the brushless motor 40, which are input with the d-axis current Id, the q-axis current Iq, the d-axis voltage Vd, and the angular velocity ω.

The angular velocity ω calculating unit 24cc and the positional angle θ calculating unit 24cd calculate the angular velocity ω and the positional angle θ, respectively, based on the following equation 5 and equation 6.

[ number 5]

ω＝-∫Ki·εγ·dt

[ number 6]

θ＝∫(ω-Kθ·εγ)dt

The angular velocity ω calculating unit 24cc calculates the angular velocity ω using PI (proportional integral) so that the position estimation value εγ converges to zero, and further calculates the time integral of ω, thereby outputting an estimated phase (position angle θ).

[1-1-5. Structure of drive System switching section ]

The driving mode switching unit 24a in the block diagram of the sensorless estimation unit 24 shown in fig. 2 switches between the induction driving unit 24b and the induction voltage driving unit 24c according to the rotation speed of the brushless motor 40, etc. Specifically, the drive system switching unit 24a delivers the position angle θ, the angular velocity ω, the motor current/voltage, and the angular velocity feedback control parameters necessary for motor control in real time, and thereby realizes instantaneous switching.

[1-2. Action ]

The operation of the motor control device 10 configured as described above will be described below.

[1-2-1. Action of Motor drive control ]

Fig. 5 is a flowchart showing a flow of motor drive control processing of the motor control device 10 in embodiment 1.

As shown in fig. 5, in step S001, the motor control device 10 starts motor drive control. In step S002, the motor control device 10 performs initial phase estimation. In step S003, the motor control device 10 performs polarity determination, and corrects the phase estimated by the initial phase estimation based on the determination result. Details of the initial phase estimation in step S002 and the polarity determination in step S003 are described later.

In step S004, the motor control device 10 performs motor start control by the induction drive unit 24b, and in step S005, the motor control device 10 determines whether or not the rotational speed of the brushless motor 40 is equal to or higher than a predetermined speed. When the rotational speed of the brushless motor 40 is equal to or higher than a predetermined speed (yes in step S005), the motor control device 10 switches the drive system in step S006. That is, the driving mode switching unit 24a switches from the inductance driving unit 24b to the induced voltage driving unit 24c. Next, in step S007, the motor control device 10 performs motor steady rotation control by the induced voltage driving unit 24c, in step S008, the motor control device 10 performs motor deceleration control, and in step S009, the motor control device 10 ends the motor driving control.

[1-2-2. Action of initial phase estimation section ]

Fig. 6A to 6C are diagrams for explaining problems related to initial phase estimation of the rotor 41. In fig. 6A to 6C, the initial phase estimation d-axis and the initial phase estimation q-axis are indicated by solid lines, and the actual d-axis and the actual q-axis are indicated by broken lines.

Fig. 6A shows a case where the rotor 41 having the magnet 42 inside the brushless motor 40 is in a correct relationship with the d-axis and the q-axis. The d-axis is the pole direction, and the q-axis is the direction orthogonal to the d-axis. The N-pole direction of the pole is the positive direction of the d-axis and the S-pole direction of the pole is the negative direction of the d-axis.

The initial phase estimating unit 22 estimates the initial phase of the rotor 41 by the inductance driving unit 24 b. Specifically, the initial phase of the rotor 41 is estimated during the drive period in which the command value of the motor rotation speed and the command value of the motor current are both set to 0 during 100 ms.

The inductance driving unit 24b estimates the phase using the difference (ld+.lq) between the inductance L in the d-axis direction and the inductance L in the q-axis direction, which are characteristics of the rotor 41 of the salient pole structure of the brushless motor 40. That is, although the inductance driving unit 24B performs the determination with respect to the horizontal direction (d-axis) or the vertical direction (q-axis) of the rotor 41, it is impossible to determine whether the direction is the N-pole direction or the S-pole direction even with the d-axis as shown in fig. 6B. As shown in fig. 6C, the inductance L of the d-axis and the inductance L of the q-axis of the rotor 41 have a periodicity of 2θ, and there is a problem that the initial phase is erroneously estimated to be deviated from the actual d-axis by 90 ° or 270 ° in the q-axis direction. In order to solve the above-described problem, the motor control device 10 according to embodiment 1 of the present disclosure is handled by the following polarity determination unit 23.

[1-2-3. Action of polarity determination section ]

Fig. 7 is a graph showing the magnetic saturation characteristics of an electromagnetic steel sheet as a rotor core used in a general brushless motor.

As shown in fig. 7, according to the relational expression of voltage equation v=lx (di/dt) with respect to inductance L, when inductance L is large, the time derivative of current (di/dt) becomes small, and the current change amount i per unit time becomes small. When the inductance L is small, the time derivative (di/dt) of the current increases, and the current change amount i per unit time increases. That is, when the inductance L varies, the current i also varies.

The polarity determination unit 23 uses the characteristic that the inductance L fluctuates due to magnetic saturation. The polarity determination unit 23 determines the polarity based on, for example, the magnitudes +id1 and Id2 of the amounts of change in the currents flowing by superimposing voltages +vd and-Vd of the same absolute value for the same time in the positive direction and the negative direction of the estimated d-axis, which are the results of the initial phase estimation by the initial phase estimation unit 22.

Specifically, the polarity of the magnetic pole of the initial phase estimation d-axis is determined by comparing the absolute value of the current change amount |+id1| when the voltage +vd is applied to the positive direction of the initial phase estimation d-axis with the absolute value | -id2| of the current change amount when the voltage-Vd is applied to the negative direction of the initial phase estimation d-axis. That is, if | -Id2| < |+id1|, it means that the estimated magnetic pole direction is a positive direction (N pole). In addition, if | -Id2| > |+id1|, it means that the estimated magnetic pole direction is the opposite direction (S pole).

[1-2-4. Action of polarity discrimination ]

Fig. 8 is a flowchart showing a flow of the polarity determination process of the motor control device 10 in embodiment 1.

As shown in fig. 8, in step S101, the polarity determination unit 23 starts the polarity determination process. In step S102, the polarity determination unit 23 performs an initialization process, and in step S103, the polarity determination unit 23 performs Id offset calculation when the initial phase estimation d-axis current is 0. That is, the polarity determination unit 23 sets the d-axis current Id detected by the current detection unit 21 immediately before the processing of steps S104 to S107, which will be described later, of superimposing voltages in the positive and negative directions of the d-axis as the offset current value and stores the offset current value. Since the details of the offset calculation of the d-axis current Id and the offset calculation of the q-axis current Iq (described later) will be described later (see fig. 11), the following description of fig. 8 will be made without considering the offset current value.

In step S104, the polarity determination unit 23 superimposes the voltage +vd for a predetermined period of time on the positive direction of the initial phase estimation d-axis, and in step S105, the polarity determination unit 23 integrates the current amplitude maximum value of the absolute value |+id| of the amount of change in the current value in the positive direction of the initial phase estimation d-axis (Σ+ Id). In step S106, the polarity determination unit 23 superimposes the voltage Vd on the negative direction of the initial phase estimation d-axis for a predetermined period of time, and in step S107, the polarity determination unit 23 integrates (Σ -Id) the current amplitude maximum value of the absolute value |id| of the variation amount of the current value in the negative direction of the initial phase estimation d-axis. The polarity determination unit 23 repeats the processing of steps S104 to S107 three times. In embodiment 1, the processing in steps S104 to S107 is repeated three times, but the number of repetitions is not limited to this, and may be, for example, two or four times. The same applies to the number of times of repeating the processes of steps S115 to S118 described later.

Next, in step S108, the polarity determination unit 23 compares the accumulation of the current amplitude maximum value of the absolute value of the current variation amount after the voltage is applied to the positive direction of the initial phase estimation d-axis with the accumulation of the current amplitude maximum value of the absolute value of the current variation amount after the voltage is applied to the negative direction of the initial phase estimation d-axis, and performs a process according to the comparison result. Specifically, if Σ -Id > Σ+id (yes in step S108), the polarity determination unit 23 proceeds to the process of step S109, and if Σ -Id is equal to or smaller than Σ+id (no in step S108), the polarity determination unit 23 proceeds to the process of step S110.

Since there is a possibility that the actual d-axis is in the opposite direction to the direction of the initial phase estimation d-axis, the polarity discriminating unit 23 adds 180 ° to the value of the phase at the time of initial phase estimation in step S109, and stores the result in θtmpd, which is the temporary storage location of the phase information. Since the direction of the d-axis of the initial phase estimation may be correct, the polarity determination unit 23 stores the value of the phase at the time of the initial phase estimation in θtmpd, which is a temporary storage location of the phase information, in step S110. The polarity determination unit 23 performs d-axis determination and corrects the estimated phase by the processing in steps S101 to S110 described above.

Next, the polarity determination unit 23 confirms the accuracy of the d-axis determination of the initial phase estimation d-axis.

In step S111, the polarity determination unit 23 calculates an absolute value ΔΣid= |Σ+id- Σ -id| of a difference between the accumulation of the current amplitude maximum values of the absolute values of the current variation amounts after the voltage is applied to the positive direction of the initial phase estimation d-axis and the accumulation of the current amplitude maximum values of the absolute values of the current variation amounts after the voltage is applied to the negative direction of the initial phase estimation d-axis, which are performed in steps S104 to S107. In step S112, the polarity determination unit 23 determines whether or not the absolute value ΔΣid of the difference is larger than a predetermined reference value Idth. If ΔΣid > Idth (e.g., 1A) (yes in step S112), the polarity determination unit 23 proceeds to the process in step S113, and if ΔΣid is equal to or smaller than Idth (no in step S112), the polarity determination unit 23 proceeds to the process in step S114. In step S113, the polarity determination unit 23 considers that the value of θtmpd stored in the temporary storage location as the phase information is correct, stores the value as the estimated phase, and ends the polarity determination process in step S126.

On the other hand, in the case where the process of step S114 is entered, there is a possibility that the initial phase estimation d-axis is deviated by +90° or +270°. Since this direction is the q-axis direction of the initial phase estimation, the polarity determination unit 23 performs determination again for the q-axis direction. In step S114, the polarity determination unit 23 performs Iq offset calculation when the current of the initial phase estimation q-axis is 0.

In step S115, the polarity determination unit 23 superimposes the voltage +vq for a predetermined period of time on the positive direction of the initial phase estimation q-axis, and in step S116, the polarity determination unit 23 integrates the current amplitude maximum value of the absolute value |+iq| of the variation amount of the current value in the positive direction of the initial phase estimation q-axis (Σ+iq). In step S117, the polarity determination unit 23 superimposes the voltage Vq for a predetermined period of time on the negative direction of the initial phase estimation q-axis, and in step S118, the polarity determination unit 23 integrates (Σ -Iq) the current amplitude maximum value of the absolute value |iq| of the variation amount of the current value in the negative direction of the initial phase estimation q-axis. The polarity discriminating unit 23 repeats the processing of steps S115 to S118 three times.

Next, in step S119, the polarity determination unit 23 compares the accumulation of the current amplitude maximum value of the absolute value of the current variation amount after the voltage is applied in the positive direction of the initial phase estimation q-axis with the accumulation of the current amplitude maximum value of the absolute value of the current variation amount after the voltage is applied in the negative direction of the initial phase estimation q-axis, and performs a process according to the comparison result. Specifically, if Σ—iq > Σ+iq (yes in step S119), the polarity determination unit 23 proceeds to the process of step S120, and if Σ—iq is equal to or smaller than Σ+iq (no in step S119), the polarity determination unit 23 proceeds to the process of step S121.

Since there is a possibility that the positive direction of the actual d-axis is the negative direction of the q-axis of the initial phase estimation, the polarity discriminating unit 23 adds 270 ° to the value of the phase at the time of the initial phase estimation in step S120, and stores the result in θtmpq, which is the temporary storage location of the phase information. On the other hand, since there is a possibility that the actual positive direction of the d-axis is the positive direction of the q-axis of the initial phase estimation, the polarity determination unit 23 adds 90 ° to the value of the phase at the time of the initial phase estimation in step S121, and stores the result in θtmpq as the temporary storage location of the position information.

As described above, the polarity determination unit 23 performs q-axis determination and corrects the estimated phase by the processing in steps S114 to S121.

Next, in step S122, the polarity determination unit 23 calculates an absolute value ΔΣiq= |Σ+ Iq- Σ -iq| of a difference between the accumulation of the current maximum amplitude of the absolute value of the current variation amount after the voltage is applied to the positive direction of the initial phase estimation q-axis and the accumulation of the current maximum amplitude of the absolute value of the current variation amount after the voltage is applied to the negative direction of the initial phase estimation q-axis, which are performed in steps S115 to S118. In step S123, the polarity determination unit 23 compares the absolute value ΔΣid of the difference obtained in the d-axis direction with the absolute value ΔΣiq of the difference obtained in the q-axis direction, and performs processing according to the comparison result. Specifically, if ΔΣid is equal to or greater than ΔΣiq (yes in step S123), the polarity determination unit 23 proceeds to the process of step S124, and if ΔΣid < ΔΣiq (no in step S123), the polarity determination unit 23 proceeds to the process of step S125.

In step S124, the polarity determination unit 23 regards the value of the temporary storage location θtmpd of the phase information as correct, stores the value as an estimated phase, and in step S125, the polarity determination unit 23 regards the value of the temporary storage location θtmpq of the phase information as correct, stores the value as an estimated phase. Finally, in step S126, the polarity determination unit 23 ends the polarity determination process.

[1-2-5. Polarity discrimination d-axis discrimination ]

Fig. 9 is a diagram showing an example of applied voltage and current at the time of d-axis determination in the motor control device 10 according to embodiment 1.

Next, the superposition of voltages and the accumulation of current amplitude maximum values in steps S104 to S107 in the flowchart of the polarity determination process shown in fig. 8 will be specifically described with reference to the example shown in fig. 9. In the example of fig. 9, the difference between the +id and-Id stored therein is set to be larger than the reference value Idth (e.g., 1A). First, a +vd voltage is superimposed on the positive direction of the d-axis of the initial phase estimation, and the current amplitude maximum value of +id at that time is stored. Then, the voltage of-Vd is superimposed in the negative direction of the d-axis of the initial phase estimation, and the current amplitude maximum value of-Id at this time is stored. If the saved +Id and-Id are in the relation of |Id| < |+Id|, the estimated phase estimated by the initial phase discrimination immediately before the polarity discrimination is used for the motor drive control thereafter. If in the relation of |id| > |+id|, an estimated phase obtained by adding 180 ° to an estimated phase estimated by the initial phase discrimination immediately before the polarity discrimination is used for the motor drive control thereafter. In the example of fig. 9, the estimated phase estimated by the initial phase discrimination immediately before the polarity discrimination directly becomes the estimated phase.

Thus, the motor control device 10 can correct the orientation of the N-pole S-pole to be correct even when the direction of the d-axis obtained by performing the initial phase estimation is deviated by 180 °.

[1-2-6. Determination of polarity d-axis and q-axis ]

Fig. 10 is a diagram showing an example of applied voltage and current at the time of d-axis and q-axis determination of the motor control device 10 in embodiment 1.

Next, the steps S104 to S107 and the steps S115 to S118 in the flowchart of the polarity determination process shown in fig. 8 will be specifically described with reference to the example shown in fig. 10, and the superposition of voltages and the accumulation of current amplitude maximum values will be described. As in the d-axis determination of fig. 9, first, a +vd voltage is superimposed on the positive direction of the d-axis of the initial phase estimation, and the current amplitude maximum value of +id at that time is stored.

Then, the voltage of-Vd is superimposed in the negative direction of the d-axis of the initial phase estimation, and the current amplitude maximum value of-Id at this time is stored. If the difference between the saved +Id and-Id (|+Id| -Id|) is smaller than the reference value Idth, i.e., in the relationship of | -Id|approximately equal to |+Id|, there is a possibility that the d-axis estimated by the initial phase estimation is deviated from the actual d-axis by 90 DEG or 270 deg. Therefore, the voltage is also superimposed in the q-axis direction, and the polarity is determined. As with the d-axis described above, first, a +vq voltage is superimposed on the initial phase estimation q-axis in the positive direction, and the current amplitude maximum value of +iq at that time is stored.

Then, the voltage of-Vq is superimposed in the negative direction of the q-axis of the initial phase estimation, and the current amplitude maximum value of-Iq at that time is stored. If the saved +Iq and-Iq are in the relationship of | -Iq| < |+Iq|, 90 DEG is added to the estimated phase estimated by the initial phase discrimination immediately before the polarity discrimination. If in the relation of |Iq| > |+Iq|, 270 DEG is added to the estimated phase estimated by the initial phase discrimination immediately before the polarity discrimination. In the example of fig. 10, the estimated phase estimated by the initial phase discrimination immediately before the polarity discrimination is added by 90 ° because the difference between +iq and +iq is larger than the difference between +id and-Id in the relation of |iq| < |+iq|.

Thus, the motor control device 10 can correct the orientation of the N pole S pole to be correct even when the direction of the d axis obtained by performing the initial phase estimation is deviated by 90 ° or 270 °.

[1-2-7. Polarity discrimination offset correction ]

Fig. 11 is a diagram for explaining the applied voltage and current at the time of offset correction at the time of polarity discrimination of the motor control device 10 in embodiment 1.

Next, the content of Id offset calculation in step S103 and Iq offset calculation in step S114 of fig. 8 will be described. The polarity determination unit 23 sets the average value of the current before the d-axis voltage and q-axis voltage of fig. 9 and 10 are superimposed as the offset current value and stores the average value. In the processing of steps S105, S107, S116, and S118 in fig. 8, the polarity determination unit 23 detects the maximum value of the current amplitude, and then sets the value obtained by subtracting the stored offset current value from the maximum value of the current amplitude as the final maximum value of the current amplitude. That is, for the d-axis, when the offset current value is +id0 and the measured current amplitude maximum value is +id ', +id to be obtained by the polarity discrimination can be calculated as +id= +id' -Id0 (see fig. 11). This can perform the same operation regardless of the positive and negative of Id, iq.

Thus, the motor control device 10 corrects the initial current to the offset current value, and can suppress the influence on the polarity determination even when the current value does not converge to 0. Therefore, the motor control device 10 can perform the determination with higher accuracy.

[1-3. Effect etc. ]

As described above, in embodiment 1, the motor control device 10 controls the brushless motor 40 having the rotor 41 of the salient pole structure driven by the inverter circuit 13. The motor control device 10 includes an inverter circuit 13, a current detection unit 21, an initial phase estimation unit 22, and a polarity determination unit 23. The current detecting unit 21 detects the current of the brushless motor 40. The initial phase estimating unit 22 estimates the initial phase of the brushless motor 40 based on the current detected by the current detecting unit 21. The polarity determination unit 23 determines the polarity of the magnetic pole of the brushless motor 40 based on the current detected by the current detection unit 21. The polarity determination unit 23 determines the polarity of the magnetic pole of the brushless motor 40 based on the current amplitude difference between the positive and negative directions of the d-axis and q-axis detected by the current detection unit 21 after the voltage is superimposed on the positive and negative directions of the d-axis and q-axis, respectively, with respect to the initial phase estimated by the initial phase estimation unit 22, and corrects the initial phase.

Thus, even when the original d-axis direction is erroneously estimated as the q-axis direction at the time of initial phase estimation, the motor control device 10 can determine the correct magnetic pole direction at the time of polarity determination. That is, the motor control device 10 can accurately perform magnetic pole detection even when the direction of the d-axis obtained by performing initial estimation is deviated from the correct direction by 90 ° or 270 °. Therefore, the motor control device 10 can smoothly start and accelerate the brushless motor 40 without reversing or stepping out.

As in embodiment 1, the polarity determination unit 23 of the motor control device 10 ends the polarity determination of the brushless motor 40 when the absolute value of the current amplitude difference between the positive direction and the negative direction of the d-axis detected by the current detection unit 21 after the voltage is superimposed on the positive direction and the negative direction of the d-axis is greater than the reference value Idth. When the absolute value of the current amplitude difference between the positive and negative directions of the d-axis is smaller than the reference value Idth, the polarity determination unit 23 performs the following processing. That is, the polarity determination unit 23 determines the polarity of the magnetic pole of the brushless motor 40 based on the current amplitude difference between the positive direction and the negative direction of the q-axis and the current amplitude difference between the positive direction and the negative direction of the d-axis detected by the current detection unit 21 after the voltage is superimposed on the positive direction and the negative direction of the q-axis, and corrects the initial phase.

As in embodiment 1, the polarity determination unit 23 of the motor control device 10 sets the current detected by the current detection unit 21 immediately before the voltage is superimposed in the positive and negative directions of the d-axis and the q-axis, respectively, as the offset current value. The polarity determination unit 23 determines the polarity of the magnetic pole of the brushless motor 40 based on a value obtained by subtracting the offset current value from the maximum value of the current amplitudes in the positive and negative directions of the d-axis and q-axis detected by the current detection unit 21 after superimposing the voltages in the positive and negative directions of the d-axis and q-axis, and corrects the initial phase.

Thus, the motor control device 10 can more accurately determine the correct magnetic pole direction at the time of polarity determination. Therefore, the motor can be smoothly started and accelerated without reversing, losing step, or the like.

(embodiment 2)

The motor control device in embodiment 2 will be described below with reference to fig. 12.

[2-1. Action ]

[2-1-1. Control of command Current value ]

The polarity determining unit of the motor control device in embodiment 2 is different from the polarity determining unit 23 of the motor control device 10 in embodiment 1 in that the polarity determining unit of the motor control device in embodiment 2 performs control such that the command current values (±id, ±iq) are 0A during the period of determining the polarity.

Fig. 12 shows that the state of the Id current in the case where the current control is performed in the polarity discrimination is different from the state of the Id current in the case where the current control is not performed. In fig. 12, the Id current when the current control is performed is shown by a solid line, and the Id current when the current control is not performed is shown by a broken line.

As shown in fig. 12, since the current response is fast when the current control is performed, the Id current value converges to 0A more quickly, as is known from the current state when the current control is performed.

[2-2. Effect, etc. ]

As described above, the polarity determination unit of the motor control device in embodiment 2 controls the current flowing to the brushless motor 40 to be 0 during the period in which the polarity of the magnetic poles of the brushless motor 40 is determined.

Thus, the motor control device according to embodiment 2 can reduce the interval between superimposed voltages. Therefore, the motor control device according to embodiment 2 can determine the polarity in a shorter period of time.

(other embodiments)

As described above, embodiment 1 and embodiment 2 are described as an example of the technology in the present disclosure. However, the technology in the present disclosure is not limited to this, and can be applied to embodiments in which modification, substitution, addition, omission, and the like are performed. Further, the components described in embodiment 1 and embodiment 2 can be combined to form a new embodiment.

Accordingly, other embodiments are exemplified below.

The motor control device and the salient pole structured brushless motor of the present disclosure can be mounted on a washing machine or a washing dryer. For example, in the case of using the brushless motor of the present salient pole structure and the motor control device of the present disclosure as the brushless motor and motor control device for driving the drum of the drum type washing machine, it is possible to smoothly start and increase the rotation speed without reverse rotation of the stopped drum, failure in start-up. Thus, the present disclosure can contribute to an improvement in the washing rate and a reduction in the operation time, and can provide a high-performance washing machine.

The motor control device 10 according to embodiment 1 and the motor control device according to embodiment 2 (hereinafter also referred to as "motor control device according to embodiment") are configured to not include the brushless motor 40. However, the structure of the motor control device according to the embodiment is an example of the structure of the motor control device in the present disclosure, and the motor control device in the present disclosure is not limited to the structure of the motor control device according to the embodiment. That is, the motor control device in the present disclosure may be a structure of a brushless motor including a rotor having a salient pole structure driven by an inverter circuit in the present disclosure.

Industrial applicability

The present disclosure can be applied to a motor control device that performs sensorless control of rotation of a brushless motor (permanent magnet synchronous motor) having a rotor with a salient pole structure, and a washing machine or a washing dryer in which the motor control device is mounted. Specifically, the present disclosure can be applied to, for example, a vertical washing machine, a drum type washing dryer, and the like.

Description of the reference numerals

10: a motor control device; 11: a rectifying circuit; 12: a smoothing capacitor; 13: an inverter circuit; 14a: a switching element; 14b: a switching element; 14c: a switching element; 14d: a switching element; 14e: a switching element; 14f: a switching element; 15a: a resistor; 15b: a resistor; 15c: a resistor; 20: a control circuit; 21: a current detection unit; 22: an initial phase estimation unit; 23: a polarity discriminating unit; 24: a sensorless estimation unit; 24a: a drive mode switching unit; 24b: an inductance driving section; 24ba: uvw→dq current conversion section; 24bb: a position estimation phi calculation unit; 24bc: a high-frequency current control unit; 24bd: an angular velocity omega calculation unit; 24be: a position angle θ calculation unit; 24bf: a speed current control unit; 24bg: dq→uvw voltage converting section; 24c: an induced voltage driving unit; 24ca: uvw→dq current conversion section; 24cb: a position estimation εy calculation unit; 24cc: an angular velocity omega calculation unit; 24cd: a position angle θ calculation unit; 24ce: a speed current control unit; 24cf: dq→uvw voltage converting section; 30: an alternating current power supply; 40: a brushless motor; 41: a rotor; 42: a magnet.

Claims

1. A motor control device that controls a brushless motor having a rotor with a salient pole structure driven by an inverter circuit, the motor control device comprising:

the inverter circuit;

a current detection unit that detects a current of the brushless motor;

an initial phase estimating unit that estimates an initial phase of the brushless motor based on the current detected by the current detecting unit; and

a polarity determination unit that determines the polarity of the magnetic pole of the brushless motor based on the current detected by the current detection unit,

the polarity determination unit determines the polarity of the magnetic pole of the brushless motor based on the current amplitude difference between the positive and negative directions of the d-axis and q-axis detected by the current detection unit after the voltage is superimposed on the positive and negative directions of the d-axis and q-axis, respectively, with respect to the initial phase estimated by the initial phase estimation unit, and corrects the initial phase.

2. The motor control device according to claim 1, wherein,

when the absolute value of the current amplitude difference between the positive and negative directions of the d-axis detected by the current detecting unit after the voltage is superimposed in the positive and negative directions of the d-axis is greater than a reference value, the polarity discriminating unit terminates the polarity discrimination of the brushless motor,

When the absolute value of the current amplitude difference between the positive and negative directions of the d-axis is smaller than the reference value, the polarity determination unit determines the polarity of the magnetic pole of the brushless motor based on the current amplitude difference between the positive and negative directions of the q-axis and the current amplitude difference between the positive and negative directions of the d-axis detected by the current detection unit after the voltage is superimposed on the positive and negative directions of the q-axis, and corrects the initial phase.

3. The motor control device according to claim 1 or 2, wherein,

the polarity determination unit determines the polarity of the magnetic pole of the brushless motor based on a value obtained by subtracting an offset current value from a maximum value of current amplitudes in positive and negative directions of the d-axis and q-axis detected by the current detection unit after the voltages are superimposed in the positive and negative directions of the d-axis and q-axis, using the current detected by the current detection unit immediately before the voltages are superimposed in the positive and negative directions of the d-axis and q-axis as the offset current value, and corrects the initial phase.

4. The motor control device according to any one of claims 1 to 3, wherein,

The polarity determination unit controls the current flowing to the brushless motor to be 0 during a period in which the polarity of the magnetic poles of the brushless motor is determined.

5. A washing machine or a washing dryer, equipped with the motor control device according to any one of claims 1 to 4.