Power conversion device

Abstract

To provide an electric power conversion device for position sensorless control, which accurately estimates an inductance during operation in a speed range including a low-speed range.SOLUTION: An electric power conversion device includes: a harmonic voltage generating portion that superimposes a harmonic voltage of a dc axis and a qc axis on a voltage command of the dc axis and the qc axis, according to a switching signal; and an inductance estimation portion that estimates the inductances of the dc axis and the qc axis based on an amplitude values of the harmonic currents and the harmonic voltages of the dc axis and the qc axis and the switching signal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a power conversion device, and more particularly to a power conversion device with sensorless control.

Background Art

[0002] Control techniques related to PM (Permanent Magnet) motors in which permanent magnets are arranged on the rotor are known. For PM motors, in the low-speed range from standstill to about 10% of the base speed, the harmonic superposition method may be used for sensorless control.

[0003] Patent Document 1 related to the harmonic superposition method is a method of superimposing a harmonic signal on a voltage command during operation and estimating inductance from the output values of normal dc-axis and qc-axis current controls. This method discloses a method for realizing high-precision and high-response torque control in vector control with an encoder. Furthermore, Patent Document 1 describes that it can be applied to sensorless control of the extended induced voltage method in the medium and high speed ranges.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Patent Document 1 describes that it can be applied to sensorless control of the extended induced voltage method in the medium and high speed ranges, but consideration has not been given to estimating inductance during operation in the low-speed range from standstill to about 10% of the base speed.

[0006] An object of the present invention is to provide a sensorless control power conversion device that accurately estimates the inductance during operation in a speed range including the low-speed range.

Means for Solving the Problems

[0007] A preferred example of the present invention is a power conversion device that supplies power to a magnet motor. According to a switching signal that designates either the dc axis direction or the qc axis direction as the direction in which a harmonic voltage is superimposed, when the switching signal is a first value, a harmonic voltage generation unit generates a harmonic voltage in the dc axis direction, and when the switching signal is a second value, the harmonic voltage generation unit generates a harmonic voltage in the qc axis direction. An adder that superimposes the harmonic voltage generated by the harmonic voltage generation unit when the switching signal is the first value on the voltage command of the dc axis to the power converter that generates the power to supply the harmonic voltage to the magnet motor, and an adder that superimposes the harmonic voltage generated by the harmonic voltage generation unit when the switching signal is the second value on the voltage command of the qc axis to the power converter that generates the power to supply the harmonic voltage to the magnet motor. An inductance estimation unit that estimates the inductance of the dc axis based on the amplitude value of the harmonic current of the dc axis and the amplitude value of the harmonic voltage when the switching signal is the first value, and estimates the inductance of the qc axis based on the amplitude value of the harmonic current of the qc axis and the amplitude value of the harmonic voltage when the switching signal is the second value. The of the dc axis estimated value of the inductance and both of the inductance estimated values of the qc axis is used to estimated a phase error estimation unit that outputs an estimated value of the phase error, a position / speed estimation unit that outputs an estimated value of the speed and position of the magnet motor using the estimated value of the phase error, and using the estimated value of the speed of the dc axis voltage command value and the voltage command values of the qc axis A vector control arithmetic unit that outputs, and a coordinate conversion unit that converts a direct current signal into an alternating current signal and outputs it using the estimated value of the position. The power conversion device is characterized by having these components.

Advantages of the Invention

[0008] According to the present invention, a position sensorless control power conversion device that accurately estimates the inductance during operation in a speed range including the low speed range can be realized.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0010] Hereinafter, this embodiment will be described in detail with reference to the drawings.

Example

[0011] FIG. 1 is a configuration diagram of a system including a power conversion device and a permanent magnet motor in Example 1. The permanent magnet motor 1 outputs a motor torque obtained by synthesizing a torque component due to the magnetic flux of the permanent magnet and a torque component due to the inductance of the armature winding.

[0012] The power converter 2 includes a semiconductor device as a switching element. The power converter 2 receives three-phase AC voltage command values v u * , v v * , vw * is input, and a voltage command value v u * , v v * , v w * is used to create a gate signal (on, off) voltage proportional to. When using an IGBT, which is an example of a switching element, the IGBT performs a switching operation based on the gate signal. Also, the power converter 2 outputs a voltage proportional to the DC voltage E dc which is the output of the DC voltage source 2a, and the three-phase AC voltage command values v u * , v v * , v w * to make the output voltage and rotational speed of the magnet motor 1 variable.

[0013] The current detector 3 detects the three-phase AC currents i u , i v , i w of the magnet motor 1. Here, the phase currents of two of the three phases of the magnet motor 1, for example, the u-phase and w-phase, are detected, and based on the AC condition (i u +i v +i w =0), the phase current of the v-phase can be obtained as i v =-(i u +i w ). In this embodiment, the current detector 3 is shown as being provided inside the power conversion device, but it may also be provided outside the power conversion device.

[0014] Next, each component of the control unit that controls the power converter will be described. The coordinate conversion unit 4 outputs the detected current values i dc of the three-phase AC currents i u , i v , i w to the detected current values i uc , i vc , i wc of the dc-axis and qc-axis based on the position estimated value θ dc , i qc .

[0015] The current detection calculation unit 5 calculates the current detection values ​​i dc , i qc and the amplitude value of the harmonic current Δi dc_ver , Δi qc_ver and the average value i dc_ver , i qc_ver Output.

[0016] The phase error estimator 6 estimates the current detection values ​​i dc , i qc The estimated phase error Δθ c Output.

[0017] The position / speed estimation unit 7 estimates the phase error Δθ c The estimated speed ω rc ^ and the position estimate θ dc Output.

[0018] The inductance estimation unit 8 estimates the amplitude value Δv of the harmonic voltage on the dc axis and the qc axis. h * and the amplitude value of the harmonic current Δi dc _ver , Δi qc_ver Therefore, the estimated inductance L d ^ , L q ^ Output.

[0019] The vector control calculation unit 9 calculates the current command i d * and the average value i dc_ver and the current command i on the qc axis q * and the average value i qc_ver Deviation from 、 Electric constants and estimated speed value ω of magnet motor 1 rc ^ Based on this, the voltage command v for the dc and qc axes is dc * , v qc * Output.

[0020] The harmonic voltage generating unit 10 generates the amplitude value v of the harmonic voltage.h * and the frequency f of the harmonic cc are set, and the harmonic voltage Δv on the dc axis dc * and the harmonic voltage Δv on the qc axis qc * are output.

[0021] The coordinate conversion unit 11, based on the position estimated value θ dc converts the voltage command v dc * , v qc * and the harmonic voltage Δv dc * , Δv qc * which is the sum value of v dc ** , v qc ** into the three-phase AC voltage commands v u * , v v * , v w * and outputs them to the power converter.

[0022] First, the voltage control by vector control and the basic operation of phase control in this embodiment will be described. The vector control calculation unit 9 for voltage control calculates the deviation between the d-axis current command i d * and the average value i dc_ver and, based on the deviation between the q-axis current command i q * and the average value i qc_ver calculates the PI control output Δv of d-axis current control dc_pi , the I control output Δv of d-axis current control dc_i , the PI control output Δv of q-axis current control qc_pi , and the I control output Δv of q-axis current control qc_i .

[0023] Also, the vector control calculation unit 9 calculates the PI control output Δv of d-axis current control, which is the output of the current control on the dc axis and qc axes dc_pi , the I control output Δv of d-axis current control dc_i , the PI control output Δv of q-axis current controlqc_pi 1. The I control output Δv of the q-axis current control qc_i and the speed estimated value ω rc ^ , and the electrical constants (R, L d L q K e ) of the magnet motor 1 are used to calculate the voltage commands v dc * v qc * for the dc axis and qc axis according to Equation (1).

[0024] [Number]

[0025] Here, each parameter is as follows. R: The total resistance of the magnet motor L d : The d-axis inductance, L q : The q-axis inductance K e : The induced voltage coefficient * : The set value Δv dc_pi : The PI control output of the d-axis current control, Δv dc_i : The I control output of the d-axis current control Δv qc _ pi : The PI control output of the q-axis current control, Δv qc _ i : The I control output of the q-axis current control

[0026] The harmonic voltage generation unit 10 outputs a rectangular wave or sine wave harmonic voltage Δv h * with the amplitude value v cc and frequency f dc * Δv qc * and adds it to the voltage commands v dc * v qc * to obtain v dc ** v qc **Calculate and control the three-phase voltage command v of the power converter 2 u * , v v * , v v * .

[0027]

Number

[0028] On the other hand, the phase error calculation unit 6 of the phase control has, for example, the "Initial Position Estimation Method at Stop of IPM Motor" in Transactions of the Institute of Electrical Engineers of Japan, Part D (Industrial Application), Vol. 123 (2003), No. 2, pp. 140-148 as a reference. When using this method, in the harmonic voltage generation unit 10, harmonic voltages of rectangular wave or sine wave are superimposed on the dc axis and qc axis, and the estimated value Δθ of the phase error is calculated according to Equation (3) in the phase error estimation unit 6 dc * , Δv qc * . c Calculate

[0029]

Number

[0030] Here, the definitions of the symbols in Equation (3) are as follows L d : d-axis inductance value, L q : q-axis inductance value Vv dc * : Harmonic voltage command superimposed on the dc axis, Vv qc * : Harmonic voltage command superimposed on the qc axis, V idc : Harmonic current on the dc axis, V iqc : Harmonic current on the qc axis

[0031] Also, in the position and speed estimation unit 7, the estimated value ω of the speed is calculated by the operation shown in Equation (4) so that the estimated value Δθ of the phase error is set to "zero" c ​​rc ^ and the position estimated value θ dc is controlled.

[0032]

Number

[0033] Here, each parameter is as follows. K p : Proportional gain, K i : Integral gain, s: Laplace operator However, Equation (3) is a very complex equation, and it is described that the influence due to the variation of the motor constant is large. Therefore, in the same reference, by superimposing the harmonic voltage only on one axis, the phase error Δθ is calculated by the operation shown in the simple Equation (5). c is calculated. For example, if Δv qc * = 0, then

[0034]

Number

[0035] According to Equation (5), in the axial direction where the harmonic voltage is superimposed, the inductance can be estimated from the relationship between the harmonic voltage and current, but the inductance in the axial direction where it is not superimposed cannot be estimated.

[0036] Therefore, the harmonic voltage generation unit 10, the current detection calculation unit 5, the phase error estimation unit 6, and the inductance estimation unit 8, which are the features of this embodiment, are used to improve this problem. Hereinafter, the control characteristics when these are used will be described.

[0037] FIG. 2 shows the configuration of the harmonic voltage generation unit 10 of Embodiment 1. This configuration will be described.

[0038] 10a is a rectangular wave signal related to the harmonic voltage. Its magnitude is ±1, and the frequency of the harmonic is about several hundred Hz to several thousand Hz. These values can be set to those of 10h from the outside for f cc can be set.

[0039] 10b is a switching signal Signal that determines the direction in which the harmonic voltage is superimposed. Its magnitude is ±1, and the frequency is about one fraction to one tenth of the number of the rectangular wave signals output from 10a.

[0040] 10c is a harmonic voltage generation unit in the dc axis direction. When Signal = 1, the output signal of 10c becomes 10a. Subsequently, in the multiplication unit 10d, a constant 10g, which is the amplitude value v h * of the harmonic voltage, is multiplied to calculate the harmonic voltage Δv dc * on the dc axis. The amplitude value v h * can be set to 10g from the outside.

[0041] 10e is a harmonic voltage generation unit in the qc axis direction. When Signal = -1, the output signal of 10e becomes 10a. Subsequently, in the multiplication unit 10f, a constant 10g, which is the amplitude value v h * of the harmonic voltage, is multiplied to calculate the harmonic voltage Δv dc * on the qc axis.

[0042] Figure 3 shows the configuration of the current detection calculation unit 5 in the first embodiment. This configuration will be described. 5a and 5b are L.P.F (Low Pass Filter), which output the average values i dc , i qc of the current detection values after removing the harmonic currents included in the current detection values i dc_ver , i qc_ver .

[0043] Here, the L.P.F 5a and L.P.F 5b may be a moving average filter or the like. Also, the current detection values i dc , i qc and the average value i dc_ver, i qc_ver is used to calculate the harmonic current Δi dc , Δi qc according to Equation (6).

[0044]

Equation

[0045] 5c is an FFT (Fast Fourier Transform) operation unit that outputs the amplitude values Δi dc , Δi qc of the harmonic currents Δi dc_ver , Δi qc_ver .

[0046] Figure 4 shows the configuration of the phase error estimation unit 6 in the first embodiment. This configuration will be described. 6a and 6d are differential operation units, 6b and 6e are division operation units, and 6c and 6f are proportional coefficients calculated from the inductance values of the d-axis and q-axis. Using the current detection values i dc , i qc and the harmonic voltages Δv dc * , Δv qc * and the d-axis inductance value L d , the q-axis inductance value L q , the phase error estimation values Δθ c_d , Δθ c_q are calculated according to Equations (7) and (8).

[0047]

Equation

[0048]

Equation

[0049] Taking the d-q axes with reference to the magnetic pole axis of the motor, the estimation coordinate axes used in the operation unit and the estimation unit in the embodiment are the dc-qc axes. Also, the phase error estimation value Δθc estimated by the phase error estimation unit is the estimation value Δθ of the phase error between the d-axis and the dc-axisc_d or an estimated value Δθ of the phase error between the q-axis and the qc-axis c_q .

[0050] The switching unit 6g outputs the calculated value Δθ when Signal = 1 c_q and the calculated value Δθ when Signal = -1 c_d as output signals respectively. This output signal is input to the L.P.F 6h, and Δθ c is output.

[0051] FIG. 5 shows the configuration of the inductance estimation unit 8 of the first embodiment. This configuration will be described. The inductance estimation unit 8 receives the switching signal Signal and the amplitude value Δi of the harmonic current dc _ver , Δi qc_ver . The inductance estimation unit 8 includes a constant 8a of V dc *, which is the amplitude value of the harmonic voltage Δv qc * on the dc-axis and the harmonic voltage Δv h * on the qc-axis, a constant 4f cc that is related to the frequency f cc of the harmonic, 4f cc 8b, 4f d ^ 8d, a division unit 8c, a division unit 8e, a switching unit 8f, a switching unit 8g, and a block indicated by Z q ^ that holds the value of the previous L -1 switched according to the signal of signal. Then, the inductance estimation unit 8 calculates the estimated values L d ^ , L q ^ of the inductances on the d-axis and the q-axis from equations (9) and (10).

[0052]

Equation

[0053]

Equation

[0054] The estimated values of the d-axis and q-axis inductances L calculated by the calculation d ^ 、L q ^ can also be reflected in the estimation calculation formulas of the phase errors shown in Equations (7) and (8).

[0055] Figure 6 shows a time chart regarding the phase error and inductance of Example 1. The first row is the waveform of the switching signal Signal, the second row is the harmonic voltage Δv superimposed on the dc axis dc * 、the third row is the harmonic current Δi on the dc axis dc 、the fourth row is the harmonic voltage Δv superimposed on the qc axis qc * 、the fifth row is the harmonic current Δi on the qc axis qc is.

[0056] When Signal = 1, the estimated value L of the d-axis inductance from Equation (9) d ^ 、the phase error Δθ from Equation (7) c_d is calculated, and when Signal = -1, the estimated value L of the q-axis inductance from Equation (10) q ^ 、the phase error Δθ from Equation (8) c_q can be calculated.

[0057] Thus, according to Example 1, even during the operation of the harmonic superposition type sensorless control, the estimated phase error value Δθ c and the inductances L of the d-axis and q-axis d 、L q can be estimated.

[0058] Perform sensorless control using the estimated phase error value Δθ c and the estimated inductance values L d ^ 、L q ^Feed back to the upper PLC (Programmable Logic Controller) to automatically adjust the magnitude of the speed command or torque command so that the magnet motor 1 does not go out of synchronization.

[0059] In addition, in the first embodiment, the periods at Signal = 1 and Signal = -1 may appear the same in FIG. 6, but either period may be longer. In other words, the periods of 1 and -1 of the switching signal Signal for switching the harmonic waves to estimate the inductance and phase error of each of the dc axis and the qc axis may be different between the dc axis and the qc axis.

[0060] Also, at point A in FIG. 6, although the harmonic voltage is switched, if there is no influence on the calculation timing of the phase error and the inductance instance, the harmonic voltages Δv dc * and Δv qc * There is no problem even if there is an overlapping period.

[0061] Furthermore, in this embodiment, the inductance is estimated during operation. However, the table creation unit may create a table regarding the current value and the inductance using the results measured during operation, and calculate the inductance using the created table from the next operation timing. By doing so, the calculation cost of calculating the inductance can be reduced.

[0062] Also, in FIG. 6, the harmonic voltage shows an example of a rectangular wave, but it may be a sine wave.

[0063] Here, a verification method when this embodiment is adopted will be described with reference to FIG. 7. An electric current detector 3 is attached to the power conversion device 16 that drives the magnet motor 1, and an encoder 21 is attached to the shaft of the magnet motor 1.

[0064] In the harmonic current calculation unit 23, the three-phase alternating current detected values (i uc 、i vc 、iwc ) and the position θ which is the output of the encoder are input, and by performing the same operation as the current detection calculation unit 5, the harmonic current Δi dc , Δi qc is output. In the current waveform observation unit 24, if Δi dc , Δi qc occur alternately, it is obvious that this embodiment is adopted. Also, when an encoder cannot be attached, if the current detection values (i uc , i vc , i wc ) of the three-phase alternating current are observed and the waveform is as shown in FIG. 8, it is obvious that this embodiment is adopted.

[0065] According to Embodiment 1, in the harmonic superposition type sensorless control, the phase error which is the phase difference between the control axis and the magnetic flux axis, and the d-axis and q-axis inductances of the permanent magnet motor can be estimated.

[0066] Also, according to Embodiment 1, a power conversion device for sensorless control that accurately estimates the inductance during operation in a speed range including the low speed range can be realized. Here, the low speed range refers to a speed range where the motor becomes about 10% of the base speed from a stop.

[0067] Since the d-axis and q-axis inductances during operation can be accurately estimated, an accurate saliency ratio can be obtained, and based on the saliency ratio, stable sensorless control can be performed even at high torque by performing sensorless control. Here, sensorless means control that does not require an encoder to be attached to the motor.

Embodiment

[0068] FIG. 9 is a system configuration diagram including the power conversion device and the permanent magnet motor of Embodiment 2. In Embodiment 1, the method was to give a predetermined amplitude value of the harmonic voltage, but in this embodiment, harmonic current control is added, and the inductance estimation values L d ^ , L q ^Perform calculations. In FIG. 9, the magnet motor 1, the power converter 2, the coordinate conversion unit 4, the current detection calculation unit 5, the phase error estimation unit 6, the position / velocity estimation unit 7, the vector control calculation unit 9, the coordinate conversion unit 11, and the DC voltage source 2a are the same as the components in FIG. 1.

[0069] FIG. 10 shows the harmonic voltage generation unit 10' of Example 2. In FIG. 10, 10'a to 10'f, 10'h are the same as the rectangular wave signal 10a to the multiplication unit 10f and the harmonic frequency f setting unit 10h in FIG. 2. cc 10'i and 10'k are the commands i for harmonic current, h * and 10'j and 10'l are PI (Proportional + Integral) control units.

[0070] On the dc axis, the amplitude value Δi of the harmonic current on the dc axis, dc_ver so that it follows the command i for harmonic current, h * the PI control unit 10'j calculates the amplitude value Δv of the harmonic voltage on the dc axis, dc * _ver and inputs it to the multiplication unit 10'd.

[0071] On the qc axis, the amplitude value Δi of the harmonic current on the qc axis, qc_ver so that it follows the command i for harmonic current, h * the PI control unit 10'l calculates the amplitude value Δv of the harmonic voltage on the qc axis, qc * _ver and inputs it to the multiplication unit 10'f. As a result, automatically adjusted harmonic voltages Δv on the dc axis and qc axis, dc * Δv, qc * are output from the multiplication unit 10'd and the multiplication unit 10'f.

[0072] FIG. 11 shows the configuration of the inductance estimation unit 8' of Example 2. This configuration will be described. In the figure, 8'b, 8'd, 8'f, 8'g, Z -1 are the same as the harmonic frequency f in FIG. 5cc Constant 4f related thereto cc 8b, 4f cc 8d, switching unit 8f, switching unit 8g, Z -1 is the same as that. In 8'c, the amplitude value Δv of the harmonic voltage on the dc axis input from the harmonic voltage generation unit 10' dc * _ver is input, and in 8'e, the amplitude value Δv of the harmonic voltage on the qc axis input from the harmonic voltage generation unit 10' qc * _ver is input respectively. From equations (11) and (12), the estimated values L d ^ of the inductances on the d-axis and q-axis, L q ^ are calculated.

[0073]

Number

[0074]

Number

[0075] The estimated values L of the inductances on the d-axis and q-axis calculated by the operation d ^ of L q ^ can also be reflected in the estimated calculation formulas of the phase errors shown in equations (7) and (8). With such a configuration, the amplitude value of the harmonic current can be controlled to be constant, no extra current is generated, and a highly efficient power conversion device can be provided.

Example

[0076] FIG. 12 is a system configuration diagram including the power converter and the magnet motor of Embodiment 3. This embodiment is an application of this embodiment to a magnet motor drive system. In FIG. 12, the magnet motor 1, the coordinate conversion unit 4, the current detection calculation unit 5, the phase error estimation unit 6, the position / velocity estimation unit 7, the vector control calculation unit 9, and the coordinate conversion unit 11 are the same components as those described in FIG. 1.

[0077] The magnet motor 1, which is a component in FIG. 1, is driven by a power conversion device 16. In the power conversion device 16, the coordinate converter 4, the current detection calculation unit 5, the phase error estimation unit 6, the position / velocity estimation unit 7, the inductance estimation unit 8, the vector control calculation unit 9, the harmonic voltage generation unit 10, and the coordinate conversion unit 11 in FIG. 1 are software 16a, and the power converter 2, the DC voltage source 2a, and the current detector 3 in FIG. 1 are implemented as hardware.

[0078] The software 16a is executed by a microcomputer or a processor. The amplitude value 14 of the harmonic voltage and the frequency 15 of the harmonic voltage in the software 16a can be set by an external device or an external upper device such as a digital operator 16b of the power conversion device 16 that enables the user to display and instruct functions and memories, a personal computer 17, a tablet 18, or a smartphone 19.

[0079] Note that if the configuration of Embodiment 2 is adopted, the amplitude value of the harmonic current may be used instead of the amplitude value 14 of the harmonic voltage.

[0080] If this embodiment is applied to a magnet motor drive system, estimation of the phase error and the inductance can be realized.

[0081] Also, the amplitude value 14 of the harmonic voltage and the frequency 15 of the harmonic voltage may be set on a local area network (LAN) connected to a programmable logic controller (PLC) or a computer, which is an upper device.

[0082] So far, in Embodiments 1 to 3, the current command value i d *, i q * and the current detection value i dc , i qc Using the electrical constants of the current command value i

[0083] By the way, the current command value i d * , i q * and the current detection value i dc , i qc From this, the voltage correction value Δv dc , Δv qc is created, and the operation shown in Equation (15) of adding this voltage correction value and the voltage reference value of vector control shown in Equation (14) may be performed.

[0084]

Number

[0085] Here, the definitions of the symbols in Equation (13) are as follows. Δv dc : Voltage correction value of the d-axis, Δv qc : Voltage correction value of the q-axis, Kpd: Proportional gain of d-axis current control, Kid: Integral gain of d-axis current control, Kpq: Proportional gain of q-axis current control, Kiq: Integral gain of q-axis current control s: Laplace operator.

[0086]

Number

[0087] Here, the definitions of the symbols in Equation (14) are as follows. vdc0*: d-axis voltage reference value, vqc0*: q-axis voltage reference value, Tacr: Time constant corresponding to the response frequency of current control, s: Laplace operator, K e : Induced voltage coefficient.

[0088]

Number

[0089] Also, the current command i d * , i q * and the current detection value i dc , i qc are used to create the intermediate current command value i d ** , i q ** shown in Equation (16) for vector control calculation, and the calculation shown in Equation (17) using the speed estimation value ω rc ^ and the electrical constants of the magnet motor 1 may be performed.

[0090] Also, it can be applied to a vector control method that calculates Equation (18) using the current command i d * on the dc axis, the current detection value i qc on the qc axis, the speed command ω r * and the electrical constants of the magnet motor 1.

[0091]

Number

[0092] Here, the definitions of the symbols in Equation (16) are as follows. Kpd: Proportional gain of d-axis current control, Kid: Integral gain of d-axis current control, Kpq: Proportional gain of q-axis current control, Kiq: Integral gain of q-axis current control s: Laplace operator.

[0093]

Number

[0094]

Number

[0095] Here, the definitions of the symbols in Equation (18) are as follows. R1: Primary resistance of the magnet motor, Td: Delay time constant of the current command i in the q-axis q * of the q-axis current command i.

[0096] In addition, in Examples 1 to 3, the switching element constituting the power converter 2 may be a Si (silicon) semiconductor element or a wide-bandgap semiconductor element such as SiC (silicon carbide) or GaN (gallium nitride).

Description of Reference Numerals

[0097] 2... Power converter, 3... Current detector, 4... Coordinate conversion unit, 5... Current detection calculation unit, 6... Phase error estimation unit, 7... Position / velocity estimation unit, 8, 8´... Inductance estimation unit, 9... Vector control calculation unit, 10, 10´... Harmonic voltage generation unit, 16... Power conversion device, L d ^ ... Estimated value of the d-axis inductance, L q ^ ... Estimated value of the q-axis inductance, Signal... Switching signal

Claims

1. In a power conversion device that supplies power to a magnet motor (1), According to a switching signal (Signal) that designates either the dc axis direction or the qc axis direction as the direction in which a harmonic voltage is superimposed, when the switching signal is a first value (Signal = 1), a harmonic voltage (Δvdc*) is generated in the dc axis direction, and when the switching signal is a second value (Signal = -1), a harmonic voltage (Δvqc*) is generated in the qc axis direction. A harmonic voltage generation unit (10); An adder that superimposes the harmonic voltage (Δvdc*) generated by the harmonic voltage generation unit when the switching signal is the first value on the voltage command (vdс*) of the dc axis to the power converter (2) that generates the power to be supplied to the magnet motor; An adder that superimposes the harmonic voltage (Δvqc*) generated by the harmonic voltage generation unit when the switching signal is the second value on the voltage command (vqc*) of the qc axis to the power converter (2) that generates the power to be supplied to the magnet motor; When the switching signal is the first value, the inductance of the dc axis is estimated based on the amplitude value (Δidс_ver) of the harmonic current (Δidc) obtained by subtracting the average value (idс_ver) of the dc axis current detection value from the dc axis current detection value (idc) and the amplitude value (Vh*) of the harmonic voltage. When the switching signal is the second value, the inductance of the qc axis is estimated based on the amplitude value (Δiqс_ver) of the harmonic current (Δiqc) obtained by subtracting the average value (iqс_ver) of the qc axis current detection value from the qc axis current detection value (iqc) and the amplitude value (Vh*) of the harmonic voltage. An inductance estimation unit (8); A phase error estimation unit (6) that calculates an estimated value (Δθc) of the phase error, which is calculated using the dc axis current detection value (idc), the harmonic voltage (Δvdc*), the qc axis current detection value (iqc), the harmonic voltage (Δvqc*), the d axis inductance value (Ld), and the q axis inductance value (Lq), and switches and outputs it based on the switching signal; A position / velocity estimation unit (7) that outputs an estimated value (ωrс^) of the speed and an estimated value (θdc) of the position of the magnet motor using the estimated value (Δθc) of the phase error; A vector control calculation unit (9) that outputs a voltage command value (vdс*) of the dc axis and a voltage command value (vqc*) of the qc axis using the estimated value (ωrс^) of the speed; Based on the estimated value of the position (θdc), from the added values (vdc**, vqc**) of the voltage command value of the dc axis (vdc*) and the voltage command value of the qc axis (vqc*) and the harmonic voltage of the dc axis (Δvdc*) and the harmonic voltage of the qc axis (Δvqc*), a coordinate conversion unit (11) that converts and outputs to a three-phase AC voltage command (vu*, vv*, vw*). A power conversion device characterized by having this.

2. In the power conversion device according to Claim 1, The harmonic voltage is a rectangular wave, and the switching signal has a period that is an integer multiple of the period of the harmonic voltage. A power conversion device characterized by this.

3. In the power conversion device according to Claim 1, Based on the detected value of the current of the qc axis when the switching signal is the first value and the harmonic voltage command value of the dc axis, the phase error of the dc axis is estimated. A power conversion device characterized by having the phase error estimation unit that estimates the phase error of the qc axis based on the detected value of the current of the dc axis when the switching signal is the second value and the harmonic voltage command value of the qc axis.

4. In the power conversion device according to Claim 1, The harmonic voltage is a rectangular wave or a sine wave. A power conversion device characterized by this.

5. In the power conversion device according to Claim 1, The periods when the switching signal is the first value and the second value are different in length. A power conversion device characterized by this.

6. In the power conversion device according to Claim 1, The inductance estimation unit Based on a constant representing the amplitude value of the harmonic voltage of the dc axis, the amplitude value of the harmonic current of the dc axis, and a value related to the frequency of the harmonic voltage, calculates an estimated value of the inductance of the dc axis. Based on a constant representing the amplitude value of the harmonic voltage of the qc axis, the amplitude value of the harmonic current of the qc axis, and a value related to the frequency of the harmonic voltage, calculates an estimated value of the inductance of the qc axis. A power conversion device characterized by this.

7. In the power conversion device according to Claim 1, The harmonic voltage generation unit Calculates the harmonic voltage of the dc axis based on a rectangular wave signal and the amplitude value of the harmonic voltage when the switching signal is the first value. Calculates the harmonic voltage of the qc axis based on a rectangular wave signal and the amplitude value of the harmonic voltage when the switching signal is the second value. A power conversion device characterized by this.

8. In the power conversion device according to Claim 1, The harmonic voltage generation unit is a power conversion device characterized by receiving a setting of the frequency or amplitude value of the harmonic voltage or a command of the harmonic current from an external device.

9. In the power conversion device according to claim 1, a power conversion device characterized by having a table creation unit that creates a table regarding the inductance estimated from the harmonic currents of the d-axis and q-axis.

10. In the power conversion device according to claim 1, a power conversion device characterized in that the inductances of the d-axis and q-axis estimated by the inductance estimation unit are fed back to a higher-level programmable logic controller.

11. In the power conversion device according to claim 3, the phase / speed estimation unit that outputs estimated values of the speed and position of the permanent magnet motor based on the phase error estimated by the phase error estimation unit; the vector control arithmetic unit that outputs the voltage commands of the d-axis and q-axis based on the estimated value of the speed; a current detector that detects the current of the permanent magnet motor; a power conversion device characterized by having a coordinate conversion unit that outputs the current detection values of the d-axis and q-axis from the AC quantity signal detected by the current detector based on the estimated value of the position.

12. In the power conversion device according to claim 11, outputs the amplitude value of the harmonic current of the d-axis based on the current detection value of the d-axis and the average value of the current detection values of the d-axis; a power conversion device characterized by having a current detection arithmetic unit that outputs the amplitude value of the harmonic current of the dq-axis based on the current detection values of the dq-axis and the average value of the current detection values of the dq-axis.

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