Power Conversion Equipment

Abstract

To provide a power conversion device capable of preventing an oscillatory phenomenon and achieving speed control without speed deviations even when there is an error in a secondary resistance value.SOLUTION: A power conversion device includes: a power converter that outputs, to an induction motor, a signal that makes an output frequency, an output voltage and an output current of the induction motor variable; and a control unit that controls the power converter. The control unit calculates a voltage and a current in a control shaft from the output current, with a direction of a primary current and a direction orthogonal thereto assumed to be a rotational coordinate system, calculates a first speed estimation value and a second speed estimation value from the voltage and the current, performs calculation for speed control from the first speed estimation value, and calculates a primary frequency command value from the second speed estimation value.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a power conversion device. [Background technology]

[0002] In the conventional technology, as described in Patent Document 1, the primary current direction (t-axis) and the direction perpendicular to it (m-axis) are set as the control axes (mt-axis) of a rotating coordinate system, the induced electromotive force value of the m-axis is estimated from the voltage command value of the m-axis, and the speed estimation value ω is calculated by dividing it by the magnetic flux according to (Equation 1). r0 ^ The following is calculated.

[0003]

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[0004] With this technology, the set value R1 used in (Equation 1) * Even if there is an error in the primary resistance value R1 of the induction motor, the estimated speed value ω r0 ^ The estimation error (ω r0 ^ -ω r ) does not occur, and there is a description that stable speed control can be performed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-182989 A Summary of the Invention [Problem to be solved by the invention]

[0006] In the technology of Patent Document 1, the error in the primary resistance value R1 of the induction motor (R1 * -R1) is insensitive. However, the set value R2 used in (Equation 1) * and the secondary resistance value R2 of the induction motor has an error (R2 * -R2), the slip frequency command value ω s * and slip frequency ω s There is an error (ω s * -ω s ) occurs, and the estimated speed value ω r0 ^ As a result, the motor speed and torque also continue to oscillate.

[0007] An object of the present invention is to provide a power conversion device capable of preventing an oscillation phenomenon and realizing speed control without speed deviation even when there is an error in the secondary resistance value. [Means for solving the problem]

[0008] The present invention includes a power converter that outputs a signal to the induction motor to vary the output frequency, output voltage, and output current of the induction motor, and a control unit that controls the power converter, The control unit calculates, from the output current, a voltage and a current on a control axis having a direction of the primary current and a direction perpendicular to the primary current as a rotating coordinate system, calculates a first speed estimation value and a second speed estimation value from the voltage and current, calculates speed control from the first speed estimation value, and calculates a primary frequency command value from the second speed estimation value. Effect of the Invention

[0009] According to the present invention, even if there is an error in the secondary resistance value, it is possible to prevent the oscillation phenomenon of the speed and torque of the induction motor and to realize speed control without speed deviation. [Brief description of the drawings]

[0010] [Figure 1] 1 is a configuration diagram of a first embodiment including a power conversion device and an induction motor. [Diagram 2] Vector diagram of dq axis. [Diagram 3] Vector diagram of the mt axis in Example 1. [Figure 4] Load operation characteristics when using conventional technology (R1* has some error). [Diagram 5] Load operating characteristics when using conventional technology (R1* and R2* have errors). [Figure 6] FIG. 4 is a configuration diagram of a speed / frequency / phase calculation unit in the first embodiment. [Figure 7] FIG. 4 is a configuration diagram of a second speed estimation calculation unit in the first embodiment. [Figure 8] FIG. 2 is a configuration diagram of a first speed estimation calculation unit in the first embodiment. [Figure 9] Load operation characteristics when Example 1 is used (R1* and R2* have errors). [Figure 10] FIG. 1 is a configuration diagram for verifying the implementation of the present invention. [Figure 11] FIG. 11 is a configuration diagram of a second embodiment having a power conversion device and an induction motor. [Figure 12] FIG. 11 is a configuration diagram of a third embodiment having a power conversion device and an induction motor. [Figure 13] FIG. 11 is a configuration diagram of a speed / frequency / phase calculation unit in the third embodiment. [Figure 14] FIG. 11 is a configuration diagram of a second speed estimation calculation unit in the third embodiment. [Figure 15] FIG. 11 is a configuration diagram of a first speed estimation calculation unit in the third embodiment. [Figure 16]FIG. 11 is a configuration diagram of a fourth embodiment having a power conversion device and an induction motor. [Figure 17] FIG. 13 is a configuration diagram of a speed / frequency / phase calculation unit in the fourth embodiment. [Figure 18] FIG. 13 is a configuration diagram of a fifth embodiment having a power conversion device, an induction motor, and an IOT controller. [Figure 19] FIG. 13 is a configuration diagram of a sixth embodiment having a power conversion device, an induction motor, and an external device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] This embodiment will be described in detail below with reference to the drawings. EXAMPLES

[0012] 1 shows a configuration diagram of a first embodiment including a power conversion device and an induction motor. The present embodiment relates to drive control of a power conversion device that drives an induction motor by speed sensorless vector control without using a speed sensor.

[0013] This embodiment also relates to a power conversion device that includes stable and highly accurate motor control, which suppresses torque pulsation caused by changes in the primary resistance and secondary resistance due to the winding temperature in an induction motor, and eliminates speed deviation between a speed command value and the rotational speed.

[0014] The induction motor 1 generates a magnetic flux φ 2d and the torque axis component (q axis) of current i q Torque t m occurs.

[0015] The power converter 2 includes a semiconductor element as a switching element. The power converter 2 outputs a three-phase AC voltage command value v u * , v v * , v w * and the three-phase AC voltage command value v u * , v v* , v w * Based on the output of the power converter 2, the induction motor 1 is driven, and the output voltage, output frequency, and output current of the induction motor 1 are variably controlled. An IGBT (Insulated Gate Bipolar Transistor) may be used as the switching element.

[0016] The DC power supply 3 supplies a DC voltage and a DC current to the power converter 2 .

[0017] The current detector 4 detects the three-phase AC current i of the induction motor 1. u , i v , i w Detection value i uc , i vc , i wc The current detector 4 detects the phase currents of two of the three phases of the induction motor 1, for example, the U phase and the W phase, and outputs the AC condition (i u +i v +i w =0) to change the V-phase line current to i v =-(i u +i w In this embodiment, the current detector 4 is provided inside the power conversion device, but it may be provided outside the power conversion device.

[0018] The control unit includes a coordinate conversion unit 5, a coordinate conversion unit 6, a speed / frequency / phase calculation unit 7, a reference phase calculation unit 8, an excitation current / magnetic flux setting unit 9, a speed control calculation unit 10, a coordinate conversion unit 11, a coordinate conversion unit 12, an mt-axis vector control calculation unit 13, a coordinate conversion unit 14, and a coordinate conversion unit 15, which are described below. The control unit controls the output of the power converter 2 so as to variably control the output voltage value, the output frequency value, and the output current of the induction motor 1.

[0019] The control unit is composed of a semiconductor integrated circuit (arithmetic control means) such as a microcomputer (microcomputer) or a DSP (Digital Signal Processor). Any or all of the control unit can be composed of hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array). The CPU (Central Processing Unit) of the control unit reads out a program stored in a recording device such as a memory, and executes the processing of each unit such as the coordinate conversion unit 5 described above.

[0020] Next, each component of the control unit will be described.

[0021] The coordinate conversion unit 5 converts the three-phase AC current i u , i v , i w Detection value i uc , i vc , i wc and the phase estimate θ dc to the d-axis and q-axis current detection values ​​i dc , i qc Output.

[0022] The coordinate conversion unit 6 converts the d-axis and q-axis current detection values ​​i dc , i qc and the estimated phase angle θ mt m-axis and t-axis current detection values ​​i mc , i tc Output.

[0023] The speed / frequency / phase calculation unit 7 calculates the voltage command value v mc ** , v tc ** , m-axis and t-axis current command values ​​i m * , i t * , m-axis and t-axis current detection values ​​i mc , i tc , m-axis and t-axis magnetic flux command values ​​φ m * , φt * , the second speed estimate ω r ^ , Primary frequency command value ω1 * and the electrical circuit parameters of induction motor 1 (R1, R2', L σ , M, L2) based on the first speed estimate ω of the induction motor 1 r ^ , slip frequency command value ω s * and the phase estimate θ dc Output.

[0024] The reference phase calculation unit 8 calculates a slip frequency command value ω s * Using the estimated phase angle θ from the m-axis to the d-axis mt Output.

[0025] The excitation current / magnetic flux setting unit 9 sets the excitation current command value i d * and the positive polarity d-axis secondary magnetic flux command value φ 2d * And the secondary magnetic flux command value φ of the q-axis is "0". 2q * Output.

[0026] The speed control calculation unit 10 calculates a speed command value ω r * and the estimated speed ω r ^ Deviation (ω r * -ω r ^ ) to the q-axis current command value i q * Output.

[0027] The coordinate conversion unit 11 converts the d-axis and q-axis current command values ​​i d * , i q * and the estimated phase angle θ mt m-axis and t-axis current command values ​​i m * , i t * Output.

[0028] The coordinate conversion unit 12 converts the secondary magnetic flux command values ​​φ 2d * , φ 2q * and the estimated phase angle θ mt to the magnetic flux command value φ of the m-axis and t-axis m * , φ t * Output.

[0029] The mt-axis vector control calculation unit 13 calculates the current command value i m * , i t * and the current detection value i mc , i tc is the deviation of (i m * -i mc ), (i t * -i tc ) to the m-axis and t-axis voltage command values ​​v mc * , v tc * Output.

[0030] The coordinate conversion unit 14 converts the m-axis and t-axis voltage command values ​​v mc * , v tc * and the estimated phase angle θ mt to the d-axis and q-axis voltage command values ​​v dc * , v qc * Output.

[0031] The coordinate conversion unit 15 converts the d-axis and q-axis voltage command values ​​v dc * , v qc * and the phase estimate θ dc to the three-phase AC voltage command value v u * , v v * , v w * Output.

[0032] First, we will explain the mt-axis based on the primary current related to the present invention. The mt-axis is a rotating coordinate system and is the control axis. Figure 2 is a vector diagram on the dq-axis. The direction of the magnetic flux is the d-axis, and the direction 90 degrees (π / 2) ahead of the d-axis is the q-axis. Here, the current i d and the q-axis current i q and the primary current i1 are related by (Equation 2).

[0033]

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[0034] Also, d and the phase angle θ of i1 φ is the d-axis current i d and the q-axis current i q The calculation is performed using (Equation 3).

[0035]

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[0036] Figure 3 is a vector diagram of the mt axis. The direction of the primary current is the t axis, and the direction perpendicular to the t axis is the m axis. Here, the current i m and the current i on the t axis t and the primary current i1 are related by (Equation 4).

[0037]

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[0038] Furthermore, the estimated phase angle θ from the m-axis to the d-axis mt is (Equation 5).

[0039]

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[0040] The basic operation of the conventional speed sensorless control using the speed estimation calculation shown in (Equation 1) will be described.

[0041] The excitation current / magnetic flux setting unit 9 determines the secondary magnetic flux value φ of the d-axis in the induction motor 1. 2d The current command value i required to generate d * In addition, the speed control calculation unit 10 outputs a speed command value ω r * to the estimated speed ω r0 ^ The q-axis current command value i q * Calculate the following.

[0042]

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[0043] The mt-axis vector control calculation unit 13 calculates the m-axis and t-axis current command values ​​i m * , i t * The current detection value i mc , i tc The voltage command value v on the m-axis and t-axis is controlled by PI (proportional + integral) control so that mc * , v tc * The voltage command value v mc * , v tc * are the m-axis and t-axis feedback voltage components.

[0044]

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[0045] For the purpose of explaining the basic operation, the speed / frequency / phase calculation unit 7 calculates a speed estimate ω r ^ Instead of r0 ^ In addition, the slip frequency calculation unit 71 calculates the slip frequency command value ω s * Calculate the following.

[0046]

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[0047] Furthermore, the speed estimate ω r0 ^ and slip frequency command value ω s * Using this, the speed / frequency / phase calculation unit 7 calculates the primary frequency command value ω1 according to (Equation 9). * Calculate the following.

[0048]

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[0049] The phase estimation calculation unit 75 calculates the phase θ of the magnetic flux axis of the induction motor 1 according to (Equation 10). dc Calculate the following.

[0050]

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[0051] Phase of magnetic flux axis θ d The phase estimate θ dc The above is the basic operation.

[0052] FIG. 4 shows the load operation characteristics when the conventional technique of Patent Document 1 is used for the speed estimation calculation. In this example, the setting R1 of the primary resistance value used in (Formula 1) is * Set the primary resistance R1 of induction motor 1 to 0.5 times the actual primary resistance R1, and set the secondary resistance R2 * is set to 1.0 times the actual secondary resistance value R2 of the induction motor 1. The induction motor 1 is driven at 1 Hz in the low speed range (speed command value ω r * The load torque is applied in a ramp shape from point A to point B in the figure up to 200%.

[0053] Rotational speed ω of induction motor 1 r and the estimated speed ω r0 ^ are consistent, and the primary resistance setting R1 * However, the secondary resistance value R2' used in (Equation 1) is low. * If there is an error in the sensorless control, the sensorless control may become unstable.

[0054] Figure 5 shows the secondary resistance setting R2 used in the speed estimation calculation (Equation 1). * The load operation characteristics are shown when the secondary resistance value R2 of the induction motor 1 is set to 0.5 times.

[0055] Rotational speed ω of induction motor 1 r The estimated speed ω r0 ^ The torque τ of the induction motor 1 decreases from point B onward. m and rotation speed ω r The vibration gradually increases, and there is a problem in that such a vibration phenomenon occurs.

[0056] This is because the speed estimation calculation shown in (Equation 1) uses only the voltage information of the m-axis, which causes the torque and rotation speed to vibrate. As a solution to this problem, the estimated speed value ω r ^ and the primary frequency command value ω1 * The speed estimate ω is fed back to r^^ Two types of calculations are performed:

[0057] Since the above vibration is included in both the m-axis and the t-axis, the voltage command value (v mc ** , v tc ** ) and current detection value (i mc , i tc ) to obtain the second speed estimate ω r ^^ The second speed estimate is calculated. ^^ Using the primary frequency command value ω1 * By calculating the error of the secondary resistance R2 (R2 * -R2) and suppresses vibration phenomena.

[0058] Furthermore, the first speed estimation calculation also uses the above-mentioned primary frequency command value ω1 * By using this, the speed estimate ω r ^ becomes an appropriate value and can be fed back to the speed control calculation with high accuracy.

[0059] For the reasons mentioned above, by using the present invention, the rotation speed ω r The speed estimation technique of this embodiment will now be described.

[0060] FIG. 6 shows a block diagram of the speed / frequency / phase calculation unit 7. The slip frequency calculation unit 71 calculates the q-axis current command value i q * , d-axis secondary magnetic flux command value φ 2d * , the set value M of the mutual inductance M * , and the set value T2 of the secondary time constant T2 * Using this, the slip frequency command value ω s * is calculated according to the above-mentioned (Equation 8).

[0061] In Patent Document 1, the estimated speed value ω r0 ^In this embodiment, the second speed estimation calculation unit 72 calculates a second speed estimate value ω r ^^ The first speed estimation calculation unit 73 calculates a first speed estimation value ω r ^ Calculate the following.

[0062] The adder 74 receives the slip frequency command value ω s * and the second speed estimate ω r ^^ is input, and the primary frequency command value ω1 is calculated by (Equation 11). * Output.

[0063]

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[0064] The phase estimation calculation unit 75 calculates the primary frequency command value ω1 * is input, and the phase estimate θ dc Output.

[0065] 7 shows the configuration of the second speed estimation calculation unit 72. The power cross product calculation unit 721 calculates the voltage command value v mc * , v tc * and the m-axis and t-axis current detection values ​​i mc , i tc Using the power cross product E cp ^ is calculated according to (Equation 12).

[0066]

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[0067] In the power cross product model calculation unit 722, the m-axis and t-axis current detection values ​​i mc , i tc , the second speed estimate ω r ^^ , Primary frequency command value ω1* , the electrical circuit parameter R2' of induction motor 1 * , L σ * , M * , L2 * , m-axis and t-axis magnetic flux command values ​​φ m * , φ t * Using the cross product model value E cp * is calculated according to (Equation 13).

[0068]

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[0069] The subtractor 723 subtracts the cross product value E cp ^ and the cross product model value E cp * is input, and the deviation is ΔE cp The output of the subtraction unit 723 is ΔE cp is input to the PI control calculation unit 724, and a second speed estimate value ω is calculated according to (Equation 14) by P (proportional) + I (integral) control calculation. r ^^ Calculate the following.

[0070]

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[0071] 8 shows the configuration of the first speed estimation calculation unit 73. The current command value i t * is the time constant T ACR is input to the first-order delay calculation unit 731, and its output i t * td Leakage inductance L σ The primary frequency command value ω1 is multiplied by a gain 732 related to *Together with this, these are input to a multiplier 733, and the voltage drop related to the leakage inductance is calculated.

[0072] The output value of the multiplier 733 and the voltage command value v of the m-axis mc * is input to the adder 734. The magnetic flux command value φ m * is the secondary resistance R2' converted to the primary side * is multiplied by a gain 735 related to the mutual inductance M, and the output of the gain 735 is input to an adder 736 together with the output of the adder 734.

[0073] m-axis current detection value i mc is the leakage inductance L σ and the observer time constant T obs and the combined resistance R σ * (R1 * +R2' * ), and the output of gain 737 is input to adder 738 together with the output of adder 736 .

[0074] The output of the adder 738 is the observer time constant T obs The m-axis current detection value i mc is the leakage inductance L σ and the observer time constant T obs The output of the gain 7310 is input to a subtractor 7311 together with the output of a first-order lag calculator 739.

[0075] t-axis magnetic flux command value φ t * is multiplied by a gain 7312 related to the mutual inductance M and the secondary inductance L2, and the output of the gain 7312 is input to a divider 7313 together with the output of the subtractor 7311. The output of the divider 7313 is multiplied by a gain 7314, which is -1, to obtain a first speed estimate ω r ^ is calculated according to (Equation 15).

[0076]

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[0077] FIG. 8 is a functional block diagram obtained by equivalently converting (Formula 15).

[0078] FIG. 9 shows the load operation characteristics in this embodiment (the conditions used in FIG. 5 are set). By comparing the load characteristics shown in FIG. 5 and FIG. 9, the first speed estimation value ω r ^ is the rotation speed ω r and the second speed estimate ω r ^^ > ω r ^ It can be seen that the relationship is as follows: Primary frequency command value ω1 * and the primary frequency ω1 are related by (Equation 16).

[0079]

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[0080] In (Equation 16), the second speed estimate ω r ^^ , slip frequency command value ω s * , rotational speed ω r and the slip frequency ω s Using this, the formula can be rewritten as (Formula 17).

[0081]

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[0082] (Equation 17) is converted into the second speed estimate ω r ^^ When rearranged, we get (Equation 18).

[0083]

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[0084] In other words, the set value of the secondary resistance R2 is R2 * The slip frequency command value ω related to s * and slip frequency ω s Error with (ω s * -ω s ) is the second speed estimate ω r ^^ The second speed estimate ω r ^^ Using the primary frequency command value ω1 * To calculate the primary frequency command value ω1 * is an appropriate value, and the first speed estimate ω r ^ The first speed estimate ω r ^ is the rotation speed ω r will match.

[0085] First speed estimate ω r ^ and the second speed estimate ω r ^^ do not coincide, but after point B where the torque stabilizes, the rotational speed ω r is the speed command value ω r * (1Hz in Figure 9).

[0086] In other words, according to this embodiment, the error in the secondary resistance value R2 (R2 * -R2), it is possible to prevent the vibration phenomenon of the induction motor's speed and torque, and to minimize the difference between the speed command value and the rotation speed (ω r * -ω r This makes it possible to achieve highly stable and highly accurate speed control by eliminating the speed deviation that is a problem in conventional speed control.

[0087] In the above description, the calculation of the first speed estimate value or the second speed estimate value has been described using the voltage command value or the current detection value as an example of the output voltage or output current of the induction motor. In the calculation of the first speed estimate value or the second speed estimate value, the voltage detection value may be used as the output voltage, and the current command value may be used as the output current.

[0088] Here, a configuration for verifying the implementation of this embodiment will be described with reference to Fig. 10. A voltage detector 21 and a current detector 22 are attached to a power conversion device 20 that drives an induction motor 1, and an encoder 23 is attached to the shaft of the induction motor 1.

[0089] In the first step, the mt-axis voltage, current, and magnetic flux calculation unit 24 receives the three-phase AC voltage detection value (v uc , v vc , v wc ), three-phase AC current detection value (i uc , i vc , i wc ) and the encoder output position θ are input, and the vector voltage component v dc ^ , v qc ^ , vector current component i dc ^ , i qc ^ and the detected value ω obtained by differentiating the position θ rc , and the slip frequency estimate ω s ^ Calculate the following.

[0090] In the second step, the detected vector current component i dc ^ , i qc ^ and the electric circuit parameters of induction motor 1 (the results of offline auto-tuning installed in the general-purpose inverter or the design values) are used to estimate the phase angle θ mt ^ From (Equation 19), the voltage components of the m-axis and t-axis v mc ^ , v mc^ From (Equation 20), the current component i mc ^ , i tc ^ From (Equation 21), the magnetic flux component φ m ^ , φ t ^ are derived from (Equation 22), respectively.

[0091] In the power cross product calculation unit 25, the power cross product value E is calculated using (Formula 23) and (Formula 24) corresponding to (Formula 12) and (Formula 13). cp ^ _ est , E cp * _ est These E cp ^ _ est and E cp * _ est If these values ​​match, it is clear that the present invention is adopted. In addition, the second speed estimate ω r ^^ may be calculated and observed.

[0092]

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[0093]

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[0094]

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[0095]

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[0096]

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[0097]

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[0098]

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[0099] FIG. 11 is a configuration diagram of a second embodiment having a power conversion device and an induction motor. In the first embodiment, the mt-axis vector control calculation unit calculates a voltage command value v mc * , v tc * is calculated as feedback voltage components of the m-axis and t-axis (feedback calculation). This embodiment is an example of executing a vector control calculation using both feedback calculation and feedforward calculation.

[0100] The speed / frequency / phase calculation unit 7a and the mt-axis vector control calculation unit 13a are blocks corresponding to the speed / frequency / phase calculation unit 7 and the mt-axis vector control calculation unit 13 in Fig. 1, respectively. In Fig. 11, the induction motor 1 to the coordinate conversion unit 6, the reference phase calculation unit 8 to the coordinate conversion unit 12, and the coordinate conversion unit 14 to the coordinate conversion unit 15 are the same as those in Fig. 1.

[0101] In the speed / frequency / phase calculation unit 7a, the second speed estimate value ω calculated by the speed / frequency / phase calculation unit 7 in FIG. r ^^ and the primary frequency command value ω1 * Output.

[0102] In addition, in the mt-axis vector control calculation unit 13a, the d-axis and q-axis current command values ​​i d * , i q * The m-axis and t-axis current command values ​​i m * , i t *, the electrical circuit parameters of induction motor 1 (R1 * , R2' * , L σ * , M * , L2 * ), m-axis and t-axis magnetic flux command values ​​φ m * , φ t * , the second speed estimate ω r ^^ , Primary frequency command value ω1 * In this embodiment, the voltage reference value v mc0 * , v mt0 * Calculate the following.

[0103]

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[0104] In addition, the mt-axis vector control calculation unit 13a receives the m-axis current command value i m * , m-axis current detection value i mc , t-axis current command value i t * , t-axis current detection value i tc is entered.

[0105] Here, according to (Equation 27), the current command value i m * , i t * The current detection value i mc , i tc The voltage correction value Δv on the m-axis and t-axis is calculated by PI (proportional + integral) control so that the voltage correction value Δv on the m-axis and t-axis is calculated so that the voltage correction value Δv on the t-axis is calculated. m * , Δv t * The m-axis and t-axis voltage correction values ​​Δv m * , Δv t * is the feedback operation.

[0106]

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[0107] Furthermore, according to (Equation 28), the voltage command value v mc ** , v tc ** After calculating the voltage command value v of the d-axis and q-axis after the coordinate transformation, dc * , v qc * The output voltage of the power converter 2 is controlled by this.

[0108]

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[0109] According to this embodiment, by adding a feedforward calculation to the vector control calculation section of the mt axis, more stable speed control can be realized. EXAMPLES

[0110] 12 is a configuration diagram of a power conversion device and an induction motor in a third embodiment. In the first embodiment, the speed estimation method uses an induced electromotive force on the m-axis for the first speed estimation calculation and uses the cross product of power for the second speed estimation calculation, particularly in the low speed range.

[0111] In this embodiment, in the medium to high speed range, the first speed estimation calculation uses the induced electromotive force of the t-axis, and the second speed estimation calculation uses the inner product of power. Speed / frequency / phase calculation unit 7b is a block equivalent to speed / frequency / phase calculation unit 7 in Fig. 1. In Fig. 12, the induction motor 1 to coordinate conversion unit 6 and the reference phase calculation unit 8 to coordinate conversion unit 15 are the same as those in Fig. 1.

[0112] 13 shows the configuration of speed / frequency / phase calculation unit 7b. Slip frequency calculation unit 7b1, adder 7b4, and phase estimation calculation unit 7b5 are the same as slip frequency calculation unit 71, adder 74, and phase estimation calculation unit 75 in FIG.

[0113] In this embodiment, the second speed estimation calculation unit 7b2 calculates the second speed estimate value ω r ^^ n In addition, the first speed estimation calculation unit 7b3 calculates a first speed estimation value ω r ^ n Calculate the following.

[0114] The adder 7b4 calculates the slip frequency command value ω s * and the second speed estimate ω r ^^ n is input, and the primary frequency command value ω1 is calculated by (Equation 29). * Output.

[0115]

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[0116] The phase estimation calculation unit 7b5 calculates the primary frequency command value ω1 * is input, and the phase estimate θ dc Output.

[0117] FIG. 14 shows the configuration of the second speed estimation calculation unit 7b2 in the third embodiment. In the power inner product calculation unit 7b21, the m-axis and t-axis voltage command values ​​v mc * , v tc * and the current detection value i mc , i tc Using this, the inner product value of the power E dp ^ is calculated according to (Equation 30).

[0118]

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[0119] In the power dot product model calculation unit 7b22, the m-axis and t-axis current detection values ​​imc , i tc , the second speed estimate ω r ^^ n , Electrical circuit parameters R1 of induction motor 1 * , R2 ’* , M * , L2 * , m-axis and t-axis magnetic flux command values ​​φ m * , φ t * Using the dot product model value E dp * is calculated according to (Equation 31).

[0120]

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[0121] The subtractor 7b23 subtracts the inner product value E dp ^ and the inner product model value E dp * is input, and the deviation is ΔE dp The output of the subtraction unit 7b23 is ΔE dp The second speed estimate value ω is calculated by multiplying the second speed estimate value ω by a gain 7b24, which is -1, and input to a PI control calculation unit 7b25. The second speed estimate value ω is calculated by a P (proportional) + I (integral) control calculation according to (Equation 32). r ^^ n Calculate the following.

[0122]

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[0123] FIG. 15 shows the configuration of the first speed estimation calculation unit 7b3 in the third embodiment. m * is the time constant T ACR is input to the first-order delay calculation unit 7b31, and the output i m * td Leakage inductance L σis multiplied by a gain related to 7b32.

[0124] The output of gain 7b32 is the primary frequency command value ω1 * The voltage drop related to the leakage inductance is calculated at the multiplier 7b33.

[0125] The output value of the multiplication unit 7b33 and the voltage command value v of the t axis tc * is input to the subtractor 7b34. The t-axis magnetic flux command value φ t * is the secondary resistance R2' converted to the primary side * and mutual inductance M * The output of the gain 7b35 is input to an adder 7b36 together with the output of the subtractor 7b34.

[0126] Current detection value i on the t axis tc is the leakage inductance L σ and the observer time constant T obs and the combined resistance R σ * The output of gain 7b37 is input to adder 7b38 together with the output of adder 7b36.

[0127] The output of the adder 7b38 is the observer time constant T obs The signal is input to a first-order lag calculation unit 7b39 having the following signal.

[0128] Current detection value i on the t axis tc is the leakage inductance L σ and the observer time constant T obs The output of the gain 7b310 is input to a first-order lag calculation section 7b39 and a subtraction section 7b311.

[0129] Magnetic flux command value φ of m-axis m *is multiplied by a gain 7b312 related to the mutual inductance M and the secondary inductance L2, and the output of the gain 7b312 is input to a division unit 7b313 together with the output of the subtraction unit 7b311, and the output of the division unit 7b313 is calculated as the first speed estimate value ω r ^ n Calculate the following.

[0130]

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[0131] FIG. 15 is a functional block diagram obtained by equivalently converting (Formula 33).

[0132] In (Equation 31), the second term contains the leakage inductance value L σ and its setting value L σ * is not included, and in (Equation 33), i m * = 0, the sensitivity to the leakage inductance value is low, and the first speed estimate ω r ^ n and the second speed estimate ω r ^^ n This makes the inverter robust against leakage inductance errors, and enables stable and highly accurate speed control to be achieved. EXAMPLES

[0133] 16 is a configuration diagram of a fourth embodiment having a power converter and an induction motor. In the first embodiment, the first speed estimate ω r ^ The second speed estimate ω r ^^ This was an example of speed estimation that calculates

[0134] In this embodiment, the first speed estimate ω r ^ and the second speed estimate ω r^^ The first speed estimate ω r ^ n and the second speed estimate ω r ^^ n This is an example using

[0135] Speed / frequency / phase calculation unit 7c is a block equivalent to speed / frequency / phase calculation unit 7 in Fig. 1. In Fig. 16, induction motor 1 to coordinate conversion unit 6 and reference phase calculation unit 8 to coordinate conversion unit 15 are the same as those in Fig. 1.

[0136] 17 shows the configuration of speed / frequency / phase calculation unit 7c. Slip frequency calculation unit 7c1, adder 7c4, and phase estimation calculation unit 7c5 are the same as 71, 74, and 75 in FIG.

[0137] In this embodiment, in the speed estimation calculation unit 72 using the cross product of the power, the output value ω r ^^ In the speed estimation calculation unit 7b2 using the inner product of the power, the output value ω r ^^ n Output.

[0138] In the switching calculation unit 7c10, the speed estimation value ω r ^^ In the medium to high speed range, the estimated speed value ω r ^^ n and use one of them as the second speed estimate ω r ^^ nn The output is as follows:

[0139] In addition, in the speed estimation calculation unit 73 using the induced electromotive force of the m-axis, the output value ω r ^ In addition, in the speed estimation calculation unit 7b3 using the induced electromotive force of the t-axis, the output value ω r^ n Output.

[0140] In the switching calculation unit 7c11, the speed estimation value ω r ^ In the medium to high speed range, the estimated speed value ω r ^ n and use one of them as the first speed estimate ω r ^ nn The output is as follows:

[0141] The aforementioned low speed range and medium to high speed range are determined by the speed command value ω r * If the absolute value of is less than about 10% of the rated speed, it is determined that the speed is in the low speed range, and switching calculation units 7c10 and 7c11 switch the speed estimation value so as to select a speed estimation value corresponding to the low speed range.

[0142] Speed ​​command value ω r * If the absolute value of is equal to or greater than about 10% of the rated speed, it is determined that the speed is in the medium to high speed range, and switching calculation units 7c10 and 7c11 switch the speed estimate value so as to select a speed estimate value corresponding to the medium to high speed range.

[0143] Alternatively, the control unit may compare the voltage drop related to the sum of the primary resistance value and the converted secondary resistance value with the voltage drop related to the induced electromotive force to determine whether (Formula 34) is satisfied. Specifically, if (Formula 34) is satisfied, the induction motor is in the low speed range, and switching calculation units 7c10 and 7c11 select a speed estimation value corresponding to the low speed range. Otherwise, if (Formula 34) is not satisfied, the induction motor is in the medium to high speed range, and switching calculation units 7c10 and 7c11 may be controlled to select a speed estimation value corresponding to the medium to high speed range.

[0144]

number

[0145] As in this embodiment, by switching the speed estimation value between the low speed range and the high speed range, it is possible to realize stable and highly accurate speed control in the entire speed range. EXAMPLES

[0146] 18 is a configuration diagram of a fifth embodiment having a power conversion device, an induction motor, and an IOT (Internet of Things) controller. In the first to fourth embodiments, the configuration is such that the electric circuit parameters of the induction motor 1 are set in the controller (such as a microcomputer) of the power converter.

[0147] This embodiment is a method in which the state quantity of the control is fed back to an IOT controller, which is a higher-level external device, and the machine-learned electric circuit parameters are reset in the controller, which is the control unit of the power converter.

[0148] Induction motor 1 to coordinate conversion unit 15 in Fig. 18 are the same as those in Fig. 1. Reference numeral 16 denotes an IOT controller that executes machine learning.

[0149] In this embodiment, the voltage command value v mc * , v tc * and the current detection value i mc , i tc , the first speed estimate ω r ^ and the second speed estimate ω r ^^ , slip frequency command value ω s * The IOT controller 16 performs machine learning based on the current detection waveform, etc. The IOT controller 16 performs machine learning based on the electric circuit parameters (R1 * , R2 * , L σ * , M * , L2 * ) in the controller which is the control section of the power converter 2.

[0150] Even when this embodiment is used, it is possible to realize a more stable and highly accurate control characteristic than the first embodiment. EXAMPLES

[0151] Fig. 19 is a configuration diagram of a sixth embodiment having a power conversion device, an induction motor, and an external device. This embodiment is applied to an induction motor drive system. In Fig. 19, software 20a is the same as the control unit in Fig. 1.

[0152] Induction motor 1, which is a component of Fig. 1, is driven by power conversion device 20. In power conversion device 20, coordinate conversion unit 5, coordinate conversion unit 6, speed / frequency / phase calculation unit 7, and reference phase calculation unit 8 to coordinate conversion unit 15 of Fig. 1 are implemented as software 20a. In addition, power converter 2, DC power supply 3, and current detector 4 of Fig. 1 are implemented as hardware.

[0153] In addition, the digital operator 20b, a personal computer 28, a tablet 29, a smartphone 30, or other higher-level external device can be used to set the "low-speed range / medium-high-speed range switching frequency ω chg 26," "ω c 27" can be set or changed.

[0154] If this embodiment is applied to an induction motor drive system, stable and highly accurate control characteristics can be realized in speed sensorless vector control. chg ", ω which is the control response of speed estimation 27 c " may be configured on a fieldbus such as a programmable logic controller, a local area network connecting to a computer, or an IOT controller.

[0155] Furthermore, in this embodiment, the first embodiment is disclosed, but the second to fifth embodiments may also be used.

[0156] In the above-described Examples 1 to 6, the cross product value E cp ^ (Equation 12) and the cross product model value E cp * In (Formula 13), which is a speed estimation calculation formula using the induced electromotive force of the m-axis, and (Formula 15), the current detection value i mc , i mc was used, but the current command value i m * , i t * may be substituted.

[0157] In addition, the inner product value of the power E dp ^ (Equation 30) and the inner product model value E dp * In (Equation 31), which is a speed estimation calculation formula using the induced electromotive force of the t axis, (Equation 33), the current detection value i mc , i mc was used, but the current command value i m * , i t * may be substituted.

[0158] Furthermore, in the first to sixth embodiments, the m-axis and t-axis voltage command values ​​are expressed as v mc * , v tc * (Equation 7) or v mc ** , v tc ** The current command value i m * , i t * and the current detection value i mc , i tc The intermediate current command value i shown in (Equation 35) used for vector control calculation is m ** , i t ** and the second speed estimate ω r ^^, Primary frequency command value ω1 * And, a vector control calculation shown in (Formula 36) may be performed using the electric circuit parameters of the induction motor 1.

[0159]

number

[0160]

number

[0161] Alternatively, the vector control calculation unit of the mt axis is the current command value i m * , i t * and the current detection value i mc , i tc The voltage correction value Δv of the proportional calculation component of the m axis used for vector control calculation is m_p * , the voltage correction value Δv of the integral calculation component of the m axis m_i * , the voltage correction value Δv of the proportional calculation component of the t axis t_p * , voltage correction value Δv of the integral calculation component of the t axis t_i * is generated by (Equation 37), and the second velocity value estimate ω r ^^ , Primary frequency command value ω1 *A vector control calculation using the electric circuit parameters of the induction motor 1 may be performed as shown in (Equation 38).

[0162]

number

[0163]

number

[0164] In the first to fifth embodiments, the switching elements constituting the power converter 2 may be Si (silicon) semiconductor elements or wide band gap semiconductor elements such as SiC (silicon carbide) and GaN (gallium nitride). [Explanation of symbols]

[0165] 1...induction motor, 2...power converter, 3...DC power supply, 4...current detector, 5...coordinate conversion section, 6...coordinate conversion section, 7, 7a, 7b, 7c...speed / frequency / phase calculation section, 71...slip frequency calculation section, 72, 7b2...second speed estimation calculation section, 73, 7b3...first speed estimation calculation section, 7c10, 7c11...switching calculation section, 8...reference phase calculation section, 9...excitation current / magnetic flux setting section, 10...speed control calculation section, 11...coordinate conversion section, 12...coordinate conversion section, 13...mt-axis vector control calculation unit, 14...coordinate conversion unit, 15...coordinate conversion unit, 20...power conversion device, 20a...software for the power conversion device, 20b...digital operator for the power conversion device, 21...voltage detector, 22...current detector, 23...encoder, 24...unit for calculating voltage, current, and magnetic flux of the MT axis, 25...unit for calculating the cross product of power, 26...switching frequency for a specified low speed range / medium-high speed range, 27...control response of the speed estimation calculation, 28...personal computer, 29...tablet, 30...smartphone, id * …d-axis current command value, i q * …q-axis current command value, i dc …d-axis current detection value, i qc …q-axis current detection value, v dc * , v dc ** …d-axis voltage command value, v qc * , v qc ** …q-axis voltage command value, φ 2d * …d-axis secondary magnetic flux command value, φ 2q * …q-axis secondary magnetic flux command value, i m * …m-axis current command value, i t * …t-axis current command value, i mc …current detection value of m axis, i tc …t-axis current detection value, v mc ** , v mc ** , v mc *** , v mc **** …m-axis voltage command value, v tc * , v tc ** , v tc *** , v mc **** …t-axis voltage command value, φ m * …m-axis magnetic flux command value, φ t * …t-axis magnetic flux command value, ω r * ...Speed ​​command value, ω r …rotation speed of the induction motor, ω r ^ , ω r ^ n , ω r ^ nn …first speed estimate, ω r ^^ , ω r ^^n , ω r ^^ nn … the second speed estimate, ω s * …Slip frequency command value, ω1 * …Primary frequency command value, θ mt …The estimated phase angle between the d-axis and the m-axis, θ dc …phase estimate, E cp ^…cross product value of power, E cp *…Power cross product model value, E dp ^…Power dot product, E dp *…Power dot product model value, v u , v v , v v …Three-phase AC voltage command value, i u , i v , i v …Three-phase AC current, i uc , i vc , i vc …Three-phase AC current detection value

Claims

1. a power converter that outputs a signal to the induction motor to vary an output frequency, an output voltage, and an output current of the induction motor; A control unit that controls the power converter, The control unit is Calculating a voltage and a current on a control axis having a primary current direction and a direction perpendicular thereto as a rotating coordinate system from the output current; calculating a first speed estimate and a second speed estimate from the voltage and current; calculating a speed control from the first speed estimate; a power conversion device that calculates a primary frequency command value from the second speed estimate value, the first speed estimation value is calculated using an induced electromotive force on the m-axis in a low speed range, and is calculated using an induced electromotive force on the t-axis in a medium to high speed range; A power conversion device in which the second speed estimate is calculated using a cross product of power in a low speed range and is calculated using an inner product of power in a medium to high speed range.

2. 2. The power conversion device according to claim 1, The control unit is A power conversion device that performs a vector control calculation from the second speed estimate value.

3. 2. The power conversion device according to claim 1, The control unit is a power conversion device that calculates the first speed estimation value from an m-axis voltage command value, a current detection value, a t-axis current command value, m-axis and t-axis magnetic flux command values, electric circuit parameters of the induction motor, and the primary frequency command value.

4. 2. The power conversion device according to claim 1, The control unit is a power conversion device that calculates the first speed estimation value from a t-axis voltage command value, a current detection value, an m-axis current command value, m-axis and t-axis magnetic flux command values, electric circuit parameters of the induction motor, and the primary frequency command value.

5. 2. The power conversion device according to claim 1, The control unit is Calculate the cross product of the power from the m-axis and t-axis voltage command values ​​and the current detection values; calculating a cross product model of power from m-axis and t-axis current detection values, electrical circuit parameters of the induction motor, the second speed estimate, and the primary frequency command value; A power conversion device that calculates the second speed estimate from a cross product of power and a cross product model of power.

6. 2. The power conversion device according to claim 1, The control unit is Calculate the inner product of power from the m-axis and t-axis voltage command values ​​and the current detection values; calculating an inner product model of power from m-axis and t-axis current detection values, electrical circuit parameters of the induction motor, the second speed estimate value, and the primary frequency command value; A power conversion device that calculates the second speed estimate from a power dot product and a power dot product model.

7. The power conversion device according to claim 3, The control unit is The power conversion device determines that the induction motor is in a low speed range.

8. The power conversion device according to claim 4, The control unit is A power conversion device that determines that the induction motor is in the medium to high speed range.

9. 6. The power conversion device according to claim 5, The control unit is The power conversion device determines that the induction motor is in a low speed range.

10. 7. The power conversion device according to claim 6, The control unit is A power conversion device that determines that the induction motor is in the medium to high speed range.

11. 2. The power conversion device according to claim 1, The control unit is A power conversion device that feeds back the voltage and current, the first speed estimate value, and the second speed estimate value to an external device for analysis, and corrects the resistance value and inductance value of the induction motor in accordance with the analysis.

12. 2. The power conversion device according to claim 1, The control unit is The switching frequency value for switching between low-speed and medium-high-speed control, A power conversion device that sets or changes, from an external device, the observer time constant that calculates the speed estimate value and the control response that is set in proportional control or integral control.

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