Driving control device, driving control system, and state estimation method

Abstract

In the present invention: the high-frequency voltage of a cycle Th is applied on a γ-axis, in which the phase changes such that the deviation from the phase of a rotor reaches zero, of a γδ quasi-synchronous coordinate system constituted by the γ-axis and a δ-axis which is orthogonal to the γ-axis, the detected value of the stator current of an AC motor is acquired at a cycle Ta which is a positive integral multiple of the cycle Th, the difference between the detected values of the latest two detections is obtained for each cycle Ta in the quasi-synchronous coordinate system such that the δ-axis current difference ΔIδ which is one such difference value is thereby generated, the sign of the γ-axis current included in the detected value is attached to the δ-axis current difference ΔIδ such that a positive correlation signal pc having a positive correlation with the phase deviation between the rotor and the γ-axis is thereby cyclically generated, the positive correlation signal pc is processed such that the positive correlation signal pc reaches zero, and an estimated value of the phase or speed of the rotor is generated.

Description

Drive control device, drive control system, and state estimation method

[0001] This disclosure relates to a drive control device, a drive control system, and a state estimation method.

[0002] An estimation device is known that estimates the rotor phase or velocity by applying a high-frequency voltage with a frequency higher than the driving fundamental frequency on the γ axis of a γδ quasi-synchronous coordinate system, which is composed of a γ axis that aims to synchronize with the rotor phase with zero phase deviation and a δ axis orthogonal to it. This estimation device generates a positive correlation signal that has a positive correlation with respect to the phase deviation between the rotor phase and the γ axis phase, and processes this positive correlation signal so that the positive correlation signal becomes zero to generate an estimated value of the rotor phase or velocity (see, for example, Patent Document 1).

[0003] Japanese Patent Publication No. 6150211, Japanese Unexamined Patent Publication No. 2015-208071, Japanese Unexamined Patent Publication No. 2021-164281

[0004] However, conventional techniques that use complex division operations to generate positively correlated signals may result in longer lead times to obtain estimates of the rotor's phase or velocity, or require larger circuit sizes to obtain such estimates.

[0005] This disclosure provides a drive control device, a drive control system, and a state estimation method that can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the circuit size required to obtain such an estimate.

[0006] The drive control device of the first embodiment is a drive control device that controls the drive of an AC motor in which the rotor exhibits salient pole characteristics when a high-frequency voltage with a frequency higher than the drive fundamental frequency is applied, and comprises an estimator for estimating the phase or velocity of the rotor, the estimator applies a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation with the rotor phase is zero and a δ axis orthogonal to the γ axis, the detected value of the stator current of the AC motor is acquired with a period Ta which is a positive integer multiple of the period Th, and the difference of the two most recent detected values ​​is taken for each period Ta on the γδ quasi-synchronous coordinate system, and one of the difference values ​​is the δ axis current difference ΔI δgenerates δ-axis current difference ΔI δ imparts the sign of the γ-axis current included in the detection value to thereby generate a positive correlation signal p having a positive correlation with the phase deviation between the rotor and the γ-axis ｃ is periodically generated, and signal processing is performed on the positive correlation signal p ｃ such that the positive correlation signal p ｃ becomes zero, thereby generating an estimated value of the phase or speed of the rotor.

[0007] In a drive control device according to a second aspect, in the drive control device according to the first aspect, when the γ-axis current is negative, the estimator multiplies the δ-axis current difference ΔI δ by a negative constant to generate the positive correlation signal p ｃ .

[0008] In a drive control device according to a third aspect, in the drive control device according to the first aspect, when the γ-axis current is positive, the estimator multiplies the δ-axis current difference ΔI δ by a positive constant to generate the positive correlation signal p ｃ .

[0009] A drive control device according to a fourth aspect is a drive control device that controls driving of an AC motor in which a rotor exhibits salient pole characteristics in response to application of a high-frequency voltage having a frequency higher than a fundamental driving frequency, the drive control device comprising: an estimator that estimates a phase or speed of the rotor, wherein the estimator applies a high-frequency voltage with a period Th on the γ-axis of a γδ quasi-synchronous coordinate system configured by a γ-axis whose phase changes such that a deviation from the phase of the rotor becomes zero and a δ-axis orthogonal to the γ-axis, acquires a detection value of a stator current of the AC motor at a period Ta that is a positive integer multiple of the period Th, obtains a difference between the latest two detection values for each period Ta on the γδ quasi-synchronous coordinate system, thereby generating a γ-axis current difference ΔI γ and a δ-axis current difference ΔI δ , multiplies the signum function of the δ-axis current difference ΔI δ by the γ-axis current difference ΔI γ to thereby periodically generate a positive correlation signal p having a positive correlation with the phase deviation between the rotor and the γ-axis, and performs signal processing on the positive correlation signal p ｃ such that the positive correlation signal p ｃ becomes zero, thereby ｃThe signal is processed to generate an estimate of the rotor's phase or velocity.

[0010] The fifth embodiment of the drive control system is a drive control device according to any one embodiment of the first to fourth embodiments, wherein the period Ta is the same as the period Th.

[0011] The sixth embodiment of the drive control system comprises a drive control device according to any one of the first to fifth embodiments, and the AC motor.

[0012] The seventh embodiment of the state estimation method is a method for estimating the phase or velocity of an AC motor using an estimator provided in a drive control device that controls the drive of an AC motor in which the rotor exhibits salient pole characteristics in response to the application of a high-frequency voltage with a frequency higher than the drive fundamental frequency, the method comprising: applying a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation with the rotor phase becomes zero and a δ axis orthogonal to the γ axis; acquiring a detected value of the stator current of the AC motor with a period Ta which is a positive integer multiple of the period Th; and taking the difference of the two most recent detected values ​​for each period Ta on the γδ quasi-synchronous coordinate system, thereby determining one of the difference values, the δ axis current difference ΔI δ Generates the δ-axis current difference ΔI δ By assigning the sign of the γ-axis current included in the detected value to the signal p, a positively correlated signal p has a positive correlation with respect to the phase deviation between the rotor and the γ-axis. ｃ This is generated periodically, and the positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ The signal is processed to generate an estimate of the rotor's phase or velocity.

[0013] The eighth aspect of the state estimation method is a method for estimating the phase or velocity of an AC motor using an estimator provided in a drive control device that controls the drive of an AC motor in which the rotor exhibits salient pole characteristics in response to the application of a high-frequency voltage with a frequency higher than the drive fundamental frequency, the method comprising: applying a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation with the rotor phase becomes zero and a δ axis orthogonal to the γ axis; acquiring a detected value of the stator current of the AC motor with a period Ta which is a positive integer multiple of the period Th; and taking the difference of the two most recent detected values ​​for each period Ta on the γδ quasi-synchronous coordinate system, thereby obtaining the γ-axis current difference ΔI as the difference value. γ and the δ-axis current difference ΔI δ Generates the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By multiplying by this, a positively correlated signal p, which has a positive correlation with respect to the phase deviation between the rotor and the γ-axis, is obtained. ｃ This is generated periodically, and the positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ The signal is processed to generate an estimate of the rotor's phase or velocity.

[0014] According to this disclosure, the time required to obtain an estimate of the rotor's phase or velocity can be reduced, or the circuit size required to obtain such an estimate can be reduced.

[0015] This figure shows an example of the relationship between three types of coordinate systems and rotor phase. This is a block diagram showing an example configuration of a drive control system according to one embodiment. The γ-axis current i included in the two-phase current i1, which is detected at discrete time intervals for each period Tc as the detected value of the stator current 1γ This figure shows the first method for acquiring the signal with period Ta. The positive correlation signal p ｃ This is a block diagram showing an example configuration of a phase synchronous device that generates rotor phase estimates and rotor velocity estimates by converging to zero. The δ-axis current difference ΔI is one of the difference values ​​obtained by taking the difference between the two phase currents i1 acquired for the most recent two periods Ta on the γδ quasi-synchronous coordinate system. δ This figure shows the change for each period Ta. The γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γThis figure shows a second method for acquiring the value with period Ta. The γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current 1γ This figure shows a third method for acquiring the value with period Ta. The γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current 1γ This figure shows a fourth method for obtaining the data with a period Ta.

[0016] The embodiments will be described below.

[0017] The technology disclosed herein is applicable to AC motors in which the rotor exhibits salient pole characteristics when a high-frequency voltage with a frequency higher than the driving fundamental frequency is applied. Examples of such AC motors include permanent magnet synchronous motors having permanent magnets in the rotor, wound-rotor synchronous motors, synchronous reluctance motors, hybrid field synchronous motors having permanent magnets and field windings in the rotor, and induction motors.

[0018] Embedded magnet permanent magnet synchronous motors and synchronous reluctance motors exhibit salient pole characteristics with respect to the driving voltage and current. These motors similarly exhibit salient pole characteristics when high-frequency voltages are applied. On the other hand, surface magnet permanent magnet synchronous motors and induction motors, which do not exhibit salient pole characteristics with respect to the driving voltage and current, exhibit salient pole characteristics when high-frequency voltages are applied. Hybrid field synchronous motors possess the characteristics of both permanent magnet and wound-rotor synchronous motors and can exhibit salient pole characteristics when high-frequency voltages are applied. Self-excited hybrid field synchronous motors, in particular, exhibit strong salient polarity.

[0019] This disclosure relates to a state estimation device provided in a drive control device that controls the drive of the above-mentioned AC motor. For example, this disclosure relates to a digital rotor phase velocity estimation device that estimates the phase (synonymous with position) or velocity of the rotor of the above-mentioned AC motor without using a position velocity sensor, i.e., sensorless. The shape of the applied high-frequency voltage may be rectangular. The frequency of the applied high-frequency voltage is a critically high frequency, similar to (i.e., the same as or a fraction of) the switching frequency of the power converter (carrier frequency in the case of PWM). For example, the frequency of the applied high-frequency voltage is a frequency of 1 / 6 or more and 1 or less of the switching frequency of the power converter (carrier frequency in the case of PWM).

[0020] This disclosure provides a method for estimating the rotor phase or velocity by forcibly applying a high-frequency voltage with a frequency higher than the driving fundamental frequency to an AC motor and processing the high-frequency current (response high-frequency current) generated by the application of the high-frequency voltage, as one of the sensorless vector control methods. This method is sometimes referred to as the high-frequency voltage application method.

[0021] In this specification, the constituent components of the stator voltage and stator current are divided into a driving fundamental frequency component and a high-frequency component. The driving fundamental frequency component is a component directly related to the rotational speed of the motor (i.e., a frequency component of a similar magnitude to the rotor speed (electrical speed)), while the high-frequency component is a component with a much higher frequency than the driving fundamental frequency component (the frequency value is known). In particular, in this disclosure, the high-frequency component means a component with a critically high frequency, such as being of a similar magnitude to the switching frequency of the power converter (carrier frequency in the case of PWM) (i.e., the same frequency or a fraction thereof). For example, the high-frequency component has a frequency of 1 / 6 to 1 times the switching frequency of the power converter (carrier frequency in the case of PWM).

[0022] The rotor phase to be estimated can be set at any position on the rotor, but it is common to select either the negative salient pole phase or the positive salient pole phase of the rotor as the rotor phase. As is well known to those skilled in the art, there is only an electrical phase difference of ±π / 2 [rad] between the negative and positive salient pole phases, and if one phase is known, the other phase will naturally be determined. Taking the above into consideration, unless otherwise specified, the negative salient pole phase of the rotor will be referred to as the rotor phase. Furthermore, a two-axis Cartesian coordinate system consisting of a d-axis synchronized with the rotor phase without phase difference and a q-axis orthogonal to the d-axis is called a dq-synchronous coordinate system (see Figure 1).

[0023] High-frequency voltage application methods, which involve applying a high-frequency voltage, can be further subdivided from the perspective of the coordinate system to which the high-frequency voltage is applied. Specifically, they can be subdivided into methods for applying a high-frequency voltage on an αβ fixed coordinate system and methods for applying a high-frequency voltage on a γδ quasi-synchronous coordinate system (a type of rotating coordinate system) that aims for convergence with zero phase difference to a dq synchronous coordinate system (see Figure 1). The high-frequency voltage application method covered by this disclosure is one in which a high-frequency voltage is applied on a γδ quasi-synchronous coordinate system. The high-frequency voltage application method covered by this disclosure may only involve applying a high-frequency voltage on the γ axis, that is, it may not involve applying a high-frequency voltage on the δ axis.

[0024] The technology disclosed herein may perform processing of stator currents containing high-frequency components on a γδ quasi-synchronous coordinate system. Stator current refers to the current flowing through the windings (stator windings) provided on the stator of an AC motor.

[0025] Figure 1 shows the coordinate system velocity ω specified by the control designer. γ This shows a γδ quasi-synchronous coordinate system rotating at ω. The γδ quasi-synchronous coordinate system consists of a γ axis whose phase changes such that the phase deviation from the rotor's phase is zero, and a δ axis orthogonal to the γ axis. Coordinate system velocity ω γ This can be one of the estimated rotor speed values. Rotation from the main shaft (γ axis) to the secondary shaft (δ axis) is considered positive. Unless otherwise specified, all 2x1 vector signals representing the physical quantities of the AC motor are assumed to be defined on this coordinate system.

[0026] Figure 2 is a block diagram showing one configuration example of a drive control system according to one embodiment. The drive control system 100 is a system that controls the drive of the AC motor 1. The drive control system 100 comprises the AC motor 1 and the drive control device 200.

[0027] AC motor 1 is an AC motor in which the rotor exhibits salient pole characteristics when a high-frequency voltage with a frequency higher than the driving fundamental frequency is applied.

[0028] The drive control device 200 is a digital drive control device that controls the drive of the AC motor 1. The drive control device 200 includes a power converter (inverter) 2, a current detector 3, a three-phase two-phase converter 4a, a two-phase three-phase converter 4b, vector rotators 5a and 5b, a current controller 6, a command converter 7, a speed controller 8, a fundamental wave current converter 9, a phase velocity estimater 10, a multiplier 11, and a cosine-sine signal generator 12.

[0029] The drive control device 200 includes, for example, memory and a processor (e.g., a CPU (Central Processing Unit)), and some or all of the functions of the drive control device 200 are realized by the processor operating according to a program stored in memory. Some or all of the functions of the drive control device 200 may be realized by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0030] The three-phase stator current i detected by the current detector 3 ｕ ,i ｖ ,i ｗ The current is first converted to a two-phase current i1 on the αβ fixed coordinate system by the three-phase two-phase converter 4a, and then converted to a two-phase current i1 on the γδ quasi-synchronous coordinate system by the vector rotor 5a, aiming for phase synchronization with zero phase deviation of rotor phase (same as the phase of the dq synchronous coordinate system). The fundamental wave current converter 9 converts the converted two-phase current i1 to a driving current i 1ｆ The (fundamental frequency component of the stator current) is extracted, and the extracted driving current i 1ｆThe (driving fundamental frequency component of the stator current) is sent to the current controller 6. The current controller 6 controls the two-phase driving current i on the γδ quasi-synchronous coordinate system. 1ｆ However, the current command value i for each phase １ ＊ To keep up with this, the two-phase voltage command value v for driving on the γδ quasi-synchronous coordinate system １ｆ ＊ Generates.

[0031] The current detector 3 is not limited to sensors such as CTs (Current Transformers) that detect the current flowing through the AC motor 1, but may also detect the single shunt current flowing through the DC side of the power converter 2. The single shunt current detection method uses a shunt resistor connected to the DC bus of the power converter 2 to detect the three-phase stator current i ｕ ,i ｖ ,i ｗ This is a method for detecting (see, for example, Patent Documents 2 and 3).

[0032] The single-phase high-frequency voltage command value (γ-axis high-frequency voltage command value v) of period Th received from the phase velocity estimator 10 γｈ ＊ ) is the two-phase voltage command value v for driving. １ｆ ＊ It is superimposed on the γ-axis element (γ-axis voltage command value). The superimposed and combined two-phase voltage command value v １ ＊ (The delta-axis voltage command value is the two-phase voltage command value v before superposition.) １ｆ ＊ The δ-axis element (unchanged) is sent to the vector rotator 5b. The vector rotator 5b receives the superimposed two-phase voltage command value v on the γδ quasi-synchronous coordinate system. １ ＊ The two-phase voltage command value v in the αβ fixed coordinate system １ ＊ Convert to the converted two-phase voltage command value v １ ＊ The two-phase three-phase converter 4b receives the two-phase voltage command value v in the αβ fixed coordinate system. １ ＊ The 3-phase voltage command value v ｕ ＊ ,v ｖ ＊ ,v ｗ ＊convert to three-phase voltage command value v ｕ ＊ , v ｖ ＊ , v ｗ ＊ is output as the final command value to the power converter 2. The power converter 2 generates power in accordance with the three-phase voltage command value v ｕ ＊ , v ｖ ＊ , v ｗ ＊ , applies the generated power to the AC motor 1, and drives the AC motor 1.

[0033] The phase speed estimator 10 receives, as an input, the detected value of the stator current (two-phase current i1) which is the output signal of the vector rotator 5a, and outputs a rotor phase estimated value θ α ^, a rotor (electrical) speed estimated value ω ２ｎ ^, and a single-phase high-frequency voltage command value (γ-axis high-frequency voltage command value v γｈ ＊ ). The rotor phase estimated value θ α ^ is converted into cosine and sine signals by the cosine-sine signal generator 12, and then passed to vector rotators 5a and 5b that define the γδ quasi-synchronous coordinate system. This means that the rotor phase estimated value θ α ^ is used as the phase of the γδ quasi-synchronous coordinate system (equivalent to the phase of the γ-axis).

[0034] The two-phase current command value i on the γδ quasi-synchronous coordinate system １ ＊ is obtained by converting a torque command value τ ＊ through a command converter 7, as is well known to those skilled in the art. The rotor speed estimated value ω ２ｎ ^ (estimated rotor electrical speed), which is one of the output signals from the phase speed estimator 10, is multiplied by the reciprocal of the number of pole pairs Np (a constant value) by a multiplier 11, so as to be converted into an estimated mechanical speed ω ｐ the reciprocal of the constant number of pole pairs N is multiplied by the multiplier 11 to convert it into a mechanical speed estimated value ω ２ｍ ^, and the converted mechanical speed estimated value ω ２ｍ ^ is sent to the speed controller 8. The speed controller 8 adjusts the torque command value τ such that the difference between the mechanical speed command value ω ２ｍ ^ ＊ and the mechanical speed estimated value ω ２ｍ ^ converges to zero ＊Generates the machine speed command value ω. ２ｍ ^ ＊ The torque is supplied from an external source. Figure 2 shows an example of a speed control system configuration, so the torque command value τ ＊ This is obtained as the output of the speed controller 8. If there is no command converter 7, the speed controller 8 will output the machine speed command value ω ２ｍ ^ ＊ and machine speed estimate ω ２ｍ The difference between i and ^ converges to zero. １ ＊ The torque command value τ is generated and directly input to the current controller 6. Alternatively, as is well known to those skilled in the art, if the control purpose is torque control and a speed control system is not to be configured, the speed controller 8 is unnecessary. In this case, the torque command value τ ＊ It is supplied from an external source.

[0035] The phase velocity estimator 10 is an example of an estimator for estimating the phase or velocity of the rotor of the AC motor 1. The phase velocity estimator 10 uses a high-frequency voltage v with a frequency higher than the driving fundamental frequency. γｈ This is a digital rotor phase speed estimation device (state estimation device) that estimates the phase or speed of the rotor by applying a voltage. The phase speed estimator 10 uses the driving voltage of the AC motor 1 (specifically, the two-phase voltage command value v １ｆ ＊ A high-frequency voltage v for phase estimation is applied to the γ-axis element of the γ-axis. γｈ (Specifically, the γ-axis high-frequency voltage command value v γｈ ＊ By applying the superimposed voltage, the rotor's phase or velocity is estimated.

[0036] High-frequency voltage v superimposed for phase estimation γｈ The frequency ω ｈ is, '|ω γ / ω ｈ Assume that the relationship |≪1≫ is sufficiently high. Frequency relative ratio (= |ω γ / ω ｈ |) is, for example, 0.01 or less. ω γ This represents the rotation speed of the γδ quasi-synchronous coordinate system.

[0037] The phase velocity estimator 10 is, '|ω γ / ωｈ Under the condition that the relationship |≪1』 holds, on the γ axis of the γδ quasi-synchronous coordinate system, the frequency ω ｈ The high-frequency voltage v has a period Th which is the reciprocal of the above. γｈ A high-frequency voltage v with period Th is applied on the γ axis. For example, the phase velocity estimator 10 applies a high-frequency voltage v with period Th on the γ axis. γｈ The amplitude V ｈ It should be rectangular (see Figure 3(b)).

[0038] The drive control device 200 controls the drive of the AC motor 1 (specifically, the stator current of the AC motor 1) according to a predetermined control period, which is period Tc. For example, when the drive control device 200 controls using a power converter 2 that operates based on a PWM carrier wave, the drive control device 200 controls the stator current according to the period Tc of the PWM carrier wave shown in Figure 3(d) (in other words, the carrier frequency which is the reciprocal of period Tc). In this case, period Tc can be understood as the control period of the stator current.

[0039] High-frequency voltage v applied on the γ axis for phase estimation γｈ The period Th is set, for example, to a positive even multiple of the period Tc. The upper limit of the period Th is approximately 1 / 20 of the electrical time constant (L / R) of the AC motor 1. L is the winding inductance of the AC motor 1, and R is the winding resistance of the AC motor 1. From the upper limit of the period Th, the upper limit of the period Tc is also naturally determined.

[0040] High-frequency voltage v with period Th γｈ The phase velocity estimator 10 applies the high-frequency current i shown in Figure 3(c). ｈ This is generated in the stator current as a high-frequency component of the stator current.

[0041] The phase velocity estimator 10 uses, for example, a high-frequency voltage v with period Th. γｈ The voltage is applied in synchronization with the period Tc. The phase velocity estimator 10 uses a high-frequency voltage v with period Th, as shown in Figure 3, for example. γｈ This is applied in synchronization with the discrete-time detection time (sampling time) of the stator current period Tc. In the example shown in Figure 3, a rectangular high-frequency voltage v γｈ The waveform switching time coincides with the discrete-time detection time.

[0042] In Figure 3, (a) represents the discrete-time detection time of the stator current period Tc. (b) represents the rectangular high-frequency voltage v with period Th. γｈ This represents (c) the high-frequency voltage v. γｈ The application of the high-frequency current i generates in the stator current. ｈ And, as the detected value of the stator current, the γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc, is the detected value of the stator current. 1γ This represents (d) the high-frequency voltage v. γｈ This represents the PWM carrier wave used when applying the signal. (e) represents the processing period E for estimating the phase or velocity of the stator.

[0043] The subscript k for current represents the time of separation detection at t = kTc, and the subscript k for voltage represents the voltage applied during the period from (k-1)Tc to kTc.

[0044] The phase velocity estimator 10 acquires the two-phase current i1, which is discrete-time detected with period Tc, as the detected value of the stator current, with period Ta. The period Ta is determined by the applied high-frequency voltage v γｈ The period is a positive integer multiple of the period Th. For example, the phase velocity estimator 10 acquires the two-phase current i1, which is discretely detected with period Tc as the detected value of the stator current, with a period Ta that is the same as the period Th (when period Ta is 1 times the period Th). The phase velocity estimator 10 may also acquire the two-phase current i1, which is discretely detected with period Tc as the detected value of the stator current, with a period Ta that is twice the period Th (when period Ta is twice the period Th). The shorter the period Ta, the narrower the acquisition interval of the discrete-time detected value of the stator current (two-phase current i1) used to estimate the rotor phase or velocity, and thus the accuracy of estimating the rotor phase or velocity improves.

[0045] The phase velocity estimator 10 acquires the two-phase current i1, which is detected discretely over period Tc as the stator current, over period Ta, and takes the difference of the two most recent two-phase current i1 for each period Ta on the γδ quasi-synchronous coordinate system. The phase velocity estimator 10 takes the difference of the two most recent two-phase current i1 for each period Ta on the γδ quasi-synchronous coordinate system, and takes the γ-axis current difference ΔI as that difference value. γ and the δ-axis current difference ΔI δ At least one of the two is generated periodically (preferably every period Ta).

[0046] For example, when acquiring a two-phase current i1 with a period Ta (=Th), the γ-axis current difference ΔI γ and the δ-axis current difference ΔI δ ΔI γ = i １γ,ｋ＋１ -i １γ,ｋ－１ ΔI δ = i １δ,ｋ＋１ -i １δ,ｋ－１ It is expressed as i １γ i is the γ-axis current (stator current on the γ axis) included in the two-phase current i1. １δ This is the delta-axis current (stator current on the delta axis) included in the two-phase current i1.

[0047] Alternatively, when acquiring the two-phase current i1 with a period Ta (= 2 × Th), the γ-axis current difference ΔI γ and the δ-axis current difference ΔI δ ΔI γ = i １γ,ｋ＋３ -i １γ,ｋ－１ ΔI δ = i １δ,ｋ＋３ -i １δ,ｋ－１ It is expressed as follows.

[0048] The phase velocity estimator 10 calculates the γ-axis current difference ΔI γ and the δ-axis current difference ΔI δ Using at least one of the following, the phase difference θ between the rotor (d axis) and the γ axis γ A positively correlated signal p has a positive correlation with respect to this. ｃ This is generated periodically (preferably every period Ta). Positive correlation signal p ｃ The phase deviation θ γ Having a positive correlation with respect to the phase deviation θ means that γ The larger the positive correlation signal p, the greater the positive correlation. ｃ This represents the characteristic of increasing p. ｃ A more detailed method for generating it will be described later.

[0049] Positive correlation signal p ｃ This is the phase difference θ between the rotor (d-axis) and the γ-axis. γ Since it has a positive correlation with respect to, it should be called the phase deviation equivalent value (see Figure 1). Naturally, the positively correlated signal p ｃ The unit is the phase deviation θ. γ It is the same unit as rad.

[0050] The phase velocity estimator 10 uses a positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ The signal is periodically processed (preferably every period Ta) to periodically generate an estimated value of the phase of the γδ quasi-synchronous coordinate system (preferably every period Ta). Phase deviation θ γ A positively correlated signal p has a positive correlation with respect to this. ｃ Reducing the phase deviation θ to zero γ This means reducing the value to zero, and consequently causing the γδ quasi-synchronous coordinate system to converge to the dq synchronous coordinate system (see Figure 1). The phase of the γδ quasi-synchronous coordinate system (γ axis) and its derivative equivalent correspond to the estimated rotor phase and velocity in an AC motor. Therefore, the rotor phase estimate and rotor velocity estimate can be obtained from the phase of the γδ quasi-synchronous coordinate system (phase of the γ axis).

[0051] Figure 4 shows the positive correlation signal p. ｃ This is a block diagram showing an example configuration of a phase synchronous device that generates rotor phase estimates and rotor velocity estimates by converging to zero. The phase velocity estimator 10 has a phase synchronous device 20. The phase synchronous device 20 is configured based on the digital generalized integral type PLL method. ｐ K is the constant of proportionality. Ｉ is the integration constant, and s is the Laplace operator.

[0052] The phase synchronous converter 20 receives a positive correlation signal p ｃ The input signal is the phase of the γδ quasi-synchronous coordinate system (in this example, the phase of the γδ quasi-synchronous coordinate system is equivalent to the rotor phase estimate θ). α ^ and the velocity ω in the γδ quasi-synchronous coordinate system γ It outputs the coordinate system velocity ω. γ This is the estimated rotor (electric) speed ω ２ｎ It is effectively identical to ^.

[0053] Thus, the phase velocity estimator 10 determines the phase deviation θ γ A positively correlated signal p has a positive correlation with respect to this. ｃ By using this method, the rotor's phase or velocity can be estimated with very little computation.

[0054] Next, the positive correlation signal p ｃWe will now describe some more detailed methods for generating it.

[0055] <Positive correlation signal p> ｃ First example of generation method > Figure 3 shows the γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γ This shows a first method for obtaining the amplitude V with period Ta. ｈ High-frequency voltage v γｈ Since it is applied on the γ axis of the γδ quasi-synchronous coordinate system, the γ-axis current i is included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γ As shown in Figure 3, the frequency changes alternately between positive and negative values. Therefore, the phase velocity estimator 10 uses the high-frequency voltage v γｈ The γ-axis current i occurs at each rise period Ta. 1γ By obtaining this, the γ-axis current i obtained for each period Ta is obtained. 1γ All of these will be negative.

[0056] On the other hand, Figure 5 shows the δ-axis current difference ΔI, which is one of the difference values ​​obtained by taking the difference between the two phase currents i1 acquired for each period Ta on the γδ quasi-synchronous coordinate system. δ This figure shows the change for each period Ta. When the estimated phase (phase of the γ axis) lags behind the actual phase (phase of the rotor (d axis)), the δ axis current difference ΔI δ This will be a positive value. When the estimated phase (phase of the γ axis) leads the actual phase (phase of the rotor (d axis)), the δ axis current difference ΔI δ This will be a negative value. Thus, the positive or negative information of the estimated phase lead or lag is the delta-axis current difference ΔI δ It is included in this.

[0057] Positive correlation signal p ｃ The first example of a generation method utilizes these features. That is, the phase velocity estimator 10 uses the δ-axis current difference ΔI δ The γ-axis current i obtained at each period Ta 1γ By assigning a sign (in this case, a negative sign) to it, the phase deviation θ γ A positively correlated signal p has a positive correlation with respect to this. ｃ (=-ΔI) δ) can be generated. For example, the phase velocity estimator 10 can generate the γ-axis current i acquired for each period Ta. 1γ When it is negative, the delta-axis current difference ΔI δ By multiplying by a negative constant (for example, -1), the phase deviation θ is obtained. γ A positively correlated signal p has a positive correlation with respect to this. ｃ (=-ΔI) δ This generates the δ-axis current difference ΔI, which is an operation variable for the estimated phase lead or lag. δ This value is treated as a gain for amplifying the signal. Note that this negative constant can be any negative value other than -1.

[0058] Conventional techniques use division to generate positively correlated signals. Since division is more complex than other arithmetic operations, it tends to take longer or require a larger circuit. This may lead to longer processing times for obtaining estimated rotor phase or velocity values, or require a larger circuit for obtaining those values.

[0059] In contrast, the positive correlation signal p ｃ According to the first example of the generation method, the δ-axis current difference ΔI δ gamma-axis current i 1γ A simple process to assign a sign to (specifically, the δ-axis current difference ΔI) δ By a simple multiplication process (multiplying by a negative constant), the positive correlation signal p ｃ This allows for the generation of a certain value. Therefore, a state estimation method including this generation method can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the size of the circuit required to obtain such an estimate.

[0060] <Positive correlation signal p> ｃ Second example of a method for generating the signal p ｃ Similar to the first example of the generation method, the phase velocity estimator 10 generates a high-frequency voltage v γｈ The γ-axis current i occurs at each rise period Ta. 1γ By obtaining this, the γ-axis current i obtained for each period Ta is obtained. 1γ Both are negative. On the other hand, in Figure 5, the positive correlation signal p ｃSimilar to the first example of the generation method, the positive or negative information of the estimated phase lead or lag is the δ-axis current difference ΔI δ It is included in this.

[0061] Positive correlation signal p ｃ The second example of the generation method also utilizes these features. That is, the phase velocity estimator 10 uses the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By multiplying by θ, the phase deviation θ γ A positively correlated signal p has a positive correlation with respect to this. ｃ (=ΔI γ ×sgn(ΔI δ This can generate the γ-axis current difference ΔI γ ΔI is the δ-axis current difference, which is the manipulated amount for the estimated phase lead or lag. δ This value is treated as a gain for amplifying the signum function.

[0062] Therefore, the positive correlation signal p ｃ According to the second example of the generation method, the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By a simple multiplication process, the positive correlation signal p ｃ This allows for the generation of a certain value. Therefore, a state estimation method including this generation method can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the size of the circuit required to obtain such an estimate.

[0063] <Positive correlation signal p> ｃ Third example of generation method > Figure 6 shows the γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γ A second method for obtaining the period Ta is shown. In the case of Figure 6, as in the case of Figure 3, the phase velocity estimator 10 obtains the high-frequency voltage v with period Th. γｈ The voltage is applied in synchronization with the period Tc. As shown in Figure 6, the phase velocity estimator 10 uses a high-frequency voltage v with period Th. γｈ This is applied in synchronization with the discrete-time detection time (sampling time) of the stator current period Tc. In the example shown in Figure 6, a rectangular high-frequency voltage v γｈ The waveform switching time coincides with the discrete-time detection time.

[0064] Amplitude V ｈ High-frequency voltage v γｈ Since it is applied on the γ axis of the γδ quasi-synchronous coordinate system, the γ-axis current i is included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γ As shown in Figure 6, it alternates between positive and negative values. Therefore, the phase velocity estimator 10 uses the high-frequency voltage v γｈ For each period Ta in which the current falls, the γ-axis current i 1γ By obtaining this, the γ-axis current i obtained for each period Ta is obtained. 1γ Both are positive. On the other hand, in Figure 5, the positive correlation signal p ｃ Similar to the first example of the generation method, the positive or negative information of the estimated phase lead or lag is the δ-axis current difference ΔI δ It is included in this.

[0065] Positive correlation signal p ｃ The third example of the generation method also utilizes these features. That is, the phase velocity estimator 10 uses the δ-axis current difference ΔI δ The γ-axis current i obtained at each period Ta 1γ By assigning a sign (in this case, a positive sign), the phase deviation θ γ A positively correlated signal p has a positive correlation with respect to this. ｃ (= +ΔI δ ) can be generated. For example, the phase velocity estimator 10 can generate the γ-axis current i acquired for each period Ta. 1γ When it is positive, the delta-axis current difference ΔI δ By multiplying by a positive constant (for example, +1), the phase deviation θ γ A positively correlated signal p has a positive correlation with respect to this. ｃ (= +ΔI δ This generates the δ-axis current difference ΔI, which is an operation variable for the estimated phase lead or lag. δ This value is treated as a gain for amplifying the signal. Note that this positive constant can be any positive value other than +1.

[0066] Therefore, the positive correlation signal p ｃ According to the third example of the generation method, the δ-axis current difference ΔI δ gamma-axis current i 1γA simple process to assign a sign to (specifically, the δ-axis current difference ΔI) δ By a simple multiplication process (multiplying by a positive constant), the positive correlation signal p ｃ This allows for the generation of a certain value. Therefore, a state estimation method including this generation method can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the size of the circuit required to obtain such an estimate.

[0067] <Positive correlation signal p> ｃ Fourth example of a method for generating the signal p: In Figure 6, the positive correlation signal p ｃ Similar to the third example of the generation method, the phase velocity estimator 10 generates a high-frequency voltage v γｈ For each period Ta in which the current falls, the γ-axis current i 1γ By obtaining this, the γ-axis current i obtained for each period Ta is obtained. 1γ Both are positive. On the other hand, in Figure 5, the positive correlation signal p ｃ Similar to the first example of the generation method, the positive or negative information of the estimated phase lead or lag is the δ-axis current difference ΔI δ It is included in this.

[0068] Therefore, the positive correlation signal p ｃ Similar to the second example of the generation method, the positive correlation signal p ｃ According to the fourth example of the generation method, the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By a simple multiplication process, the positive correlation signal p ｃ This allows for the generation of a certain value. Therefore, a state estimation method including this generation method can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the size of the circuit required to obtain such an estimate.

[0069] <Positive correlation signal p> ｃ Fifth example of generation method > Figure 7 shows the γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γ A third method for obtaining the period Ta is shown. In the case of Figure 7, as in the case of Figure 3, the phase velocity estimator 10 obtains the high-frequency voltage v with period Th. γｈ The voltage is applied in synchronization with the period Tc. As shown in Figure 7, the phase velocity estimator 10 uses a high-frequency voltage v with period Th.γｈ This is applied in a manner synchronized with the discrete-time detection time (sampling time) of the stator current period Tc. In the example shown in Figure 7, a rectangular high-frequency voltage v γｈ The waveform switching time does not coincide with the discrete time detection time. The phase velocity estimator 10 uses the high-frequency voltage v γｈ The γ-axis current i at a predetermined time after the rate has fallen off 1γ By acquiring this at each period Ta, the γ-axis current i acquired at each period Ta is obtained. 1γ All of these will be negative.

[0070] 1. In the case of the shunt current detection method, the high-frequency voltage v γｈ The waveform switching time and the discrete-time detection time of the stator current do not necessarily coincide. Even in the single-shunt current detection method, since the discrete-time detection period of the current is synchronized with the period of the PWM carrier wave, the application of the rectangular high-frequency voltage by the phase velocity estimator is performed at a time synchronized with the discrete-time detection period of the stator current.

[0071] Therefore, the positive correlation signal p ｃ Similar to the first example of the generation method, the positive correlation signal p ｃ According to the fifth example of the generation method, the δ-axis current difference ΔI δ gamma-axis current i 1γ A simple process to assign a sign to (specifically, the δ-axis current difference ΔI) δ By a simple multiplication process (multiplying by a negative constant), the positive correlation signal p ｃ It is possible to generate a positive correlation signal p. ｃ Similar to the second example of the generation method, the positive correlation signal p ｃ According to the fifth example of the generation method, the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By a simple multiplication process, the positive correlation signal p ｃ This allows for the generation of a certain value. Therefore, a state estimation method including this generation method can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the size of the circuit required to obtain such an estimate.

[0072] <Positive correlation signal p> ｃSixth example of generation method > Figure 8 shows the γ-axis current i included in the two-phase current i1, which is detected at discrete time for each period Tc as the detected value of the stator current. 1γ A fourth method for acquiring the frequency with period Ta is shown. In the case of Figure 8, similar to the one-shunt current detection method shown in Figure 7, a rectangular high-frequency voltage v is obtained. γｈ The waveform switching time does not coincide with the discrete time detection time. The phase velocity estimator 10 uses the high-frequency voltage v γｈ The γ-axis current i at a predetermined time after the start of operation 1γ By acquiring this at each period Ta, the γ-axis current i acquired at each period Ta is obtained. 1γ All of these are true.

[0073] Therefore, the positive correlation signal p ｃ Similar to the third example of the generation method, the positive correlation signal p ｃ According to the sixth example of the generation method, the δ-axis current difference ΔI δ gamma-axis current i 1γ A simple process to assign a sign to (specifically, the δ-axis current difference ΔI) δ By a simple multiplication process (multiplying by a positive constant), the positive correlation signal p ｃ It is possible to generate a positive correlation signal p. ｃ Similar to the fourth example of the generation method, the positive correlation signal p ｃ According to the sixth example of the generation method, the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By a simple multiplication process, the positive correlation signal p ｃ This allows for the generation of a certain value. Therefore, a state estimation method including this generation method can shorten the time required to obtain an estimate of the rotor's phase or velocity, or reduce the size of the circuit required to obtain such an estimate.

[0074] As described above, embodiments have been explained, but these embodiments are presented as examples only, and the present invention is not limited by these embodiments. The above embodiments can be implemented in various other forms, and various combinations, omissions, substitutions, and modifications are possible without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims of the invention and its equivalents.

[0075] This international application claims priority based on Japanese Patent Application No. 2025-029464, filed on 26 February 2025, and the entire contents of Japanese Patent Application No. 2025-029464 are incorporated herein by reference.

[0076] 1 AC motor 2 Power converter 3 Current detector 4a 3-phase 2-phase converter 4b 2-phase 3-phase converter 5a Vector rotator 5b Vector rotator 6 Current controller 7 Command converter 8 Speed ​​controller 9 Fundamental wave current converter 10 Phase velocity estimator 11 Multiplier 12 Cosine-sine signal generator 20 Phase synchronous converter 100 Drive control system 200 Drive control device

Claims

1. A drive control device for controlling the drive of an AC motor in which the rotor exhibits salient pole characteristics when a high-frequency voltage with a frequency higher than the driving fundamental frequency is applied, comprising an estimator for estimating the phase or velocity of the rotor, wherein the estimator applies a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation with the rotor phase is zero and a δ axis orthogonal to the γ axis, acquires a detected value of the stator current of the AC motor with a period Ta which is a positive integer multiple of the period Th, and takes the difference of the two most recent detected values ​​for each period Ta on the γδ quasi-synchronous coordinate system, thereby obtaining one of the difference values, the δ axis current difference ΔI δ Generates the δ-axis current difference ΔI δ By assigning the sign of the γ-axis current included in the detected value to the signal p, a positively correlated signal p has a positive correlation with respect to the phase deviation between the rotor and the γ-axis. ｃ This is generated periodically, and the positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ A drive control device that processes signals to generate an estimate of the phase or velocity of the rotor.

2. When the γ-axis current is negative, the estimator calculates the δ-axis current difference ΔI δ By multiplying by a negative constant, the positive correlation signal p is obtained. ｃ A drive control device according to claim 1, which generates a 3. The estimator is configured to, when the γ-axis current is positive, obtain the δ-axis current difference ΔI δ multiplied by a positive constant to generate a positive correlation signal p ｃ as generated, the drive control apparatus according to claim 1.

4. A drive control device for controlling the drive of an AC motor in which the rotor exhibits salient pole characteristics when a high-frequency voltage with a frequency higher than the driving fundamental frequency is applied, comprising an estimator for estimating the phase or velocity of the rotor, wherein the estimator applies a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation with the rotor phase is zero and a δ axis orthogonal to the γ axis, acquires a detected value of the stator current of the AC motor with a period Ta which is a positive integer multiple of the period Th, and takes the difference of the two most recent detected values ​​for each period Ta on the γδ quasi-synchronous coordinate system, thereby obtaining the γ-axis current difference ΔI as the difference value. γ and the δ-axis current difference ΔI δ Generates the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By multiplying by this, a positively correlated signal p, which has a positive correlation with respect to the phase deviation between the rotor and the γ-axis, is obtained. ｃ This is generated periodically, and the positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ A drive control device that processes signals to generate an estimate of the phase or velocity of the rotor.

5. The drive control device according to any one of claims 1 to 4, wherein the period Ta is the same as the period Th.

6. A drive control system comprising the drive control device according to any one of claims 1 to 4, and the AC motor.

7. A method for estimating the phase or velocity of an AC motor using an estimator provided in a drive control device that controls the drive of an AC motor in which the rotor exhibits salient pole characteristics when a high-frequency voltage with a frequency higher than the driving fundamental frequency is applied, comprising: applying a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation from the rotor phase is zero and a δ axis orthogonal to the γ axis; acquiring a detected value of the stator current of the AC motor with a period Ta which is a positive integer multiple of the period Th; and taking the difference of the two most recent detected values ​​for each period Ta on the γδ quasi-synchronous coordinate system, thereby obtaining the δ axis current difference ΔI, which is one of the difference values. δ Generates the δ-axis current difference ΔI δ By assigning the sign of the γ-axis current included in the detected value to the signal p, a positively correlated signal p has a positive correlation with respect to the phase deviation between the rotor and the γ-axis. ｃ This is generated periodically, and the positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ A state estimation method that processes signals to generate an estimate of the phase or velocity of the rotor.

8. A method for estimating the phase or velocity of an AC motor using an estimator provided in a drive control device that controls the drive of an AC motor in which the rotor exhibits salient pole characteristics in response to the application of a high-frequency voltage with a frequency higher than the driving fundamental frequency, comprising: applying a high-frequency voltage with period Th on the γ axis of a γδ quasi-synchronous coordinate system composed of a γ axis whose phase changes so that the deviation from the rotor phase is zero and a δ axis orthogonal to the γ axis; acquiring a detected value of the stator current of the AC motor with a period Ta which is a positive integer multiple of the period Th; and taking the difference of the two most recent detected values ​​for each period Ta on the γδ quasi-synchronous coordinate system, thereby obtaining the γ-axis current difference ΔI as the difference value. γ and the δ-axis current difference ΔI δ Generates the δ-axis current difference ΔI δ The signum function of the γ-axis current difference ΔI γ By multiplying by this, a positively correlated signal p, which has a positive correlation with respect to the phase deviation between the rotor and the γ-axis, is obtained. ｃ This is generated periodically, and the positive correlation signal p ｃ The positive correlation signal p becomes zero. ｃ A state estimation method that processes signals to generate an estimate of the phase or velocity of the rotor.

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