Control device

Abstract

A control device (200) includes an electric-power conversion portion (5), an electric-current detection portion (6), a first error-detection processing portion (10), a three-phase electric-current calculation portion (9), and an electric-current control portion (2). The electric-power conversion portion (5) supplies electric power to a three-phase motor (1). The electric-current detection portion (6) detects a value of the electric current flowing through each phase of the three-phase motor (1). The first error-detection processing portion (10) detects an inter-phase gain error of the electric-current detection portion (6) on the basis of the calculated value of a zero-phase current. The three-phase electric-current calculation portion (9) corrects the value of the electric current of each phase detected by the electric-current detection portion (6). The electric-current control portion (2) calculates a voltage command value for the electric-power conversion portion (5).

Description

control device

[0001] The present disclosure relates to a controller for controlling a three-phase motor.

[0002] Patent Document 1 describes a device for controlling a three-phase motor. In the device described in Patent Document 1, the detected current values ​​of each phase are converted into d-axis current values ​​and q-axis current values. Furthermore, a current detection error is detected from the amplitude value of 2f vibration of the converted d-axis current.

[0003] Japanese Patent No. 5984166

[0004] The device described in Patent Document 1 detects current detection errors from the amplitude value of the 2f vibration of the d-axis current. However, current detection errors are not the only main cause of 2f vibration of the d-axis current. Magnetic circuit errors in three-phase motors can also be a major cause of 2f vibration of the d-axis current. Therefore, the device described in Patent Document 1 has the problem of being unable to accurately detect current detection errors.

[0005] The present disclosure has been made to solve the above-mentioned problems, and an object of the present disclosure is to provide a control device for controlling a three-phase motor, which is capable of detecting a current detection error with high accuracy.

[0006] The control device according to the present disclosure includes a power conversion unit that supplies power to a three-phase motor, a current detection unit that detects the value of a current flowing through each phase of the three-phase motor, a first error detection processing unit that calculates a value of a zero-phase current based on the value of the current of each phase detected by the current detection unit and detects a phase-to-phase gain error of the current detection unit based on the calculated value of the zero-phase current, a three-phase current calculation unit that corrects the value of the current of each phase detected by the current detection unit based on the phase-to-phase gain error detected by the first error detection processing unit, and a current control unit that calculates a voltage command value for the power conversion unit based on a current command value and the value of the current of each phase corrected by the three-phase current calculation unit.

[0007] According to the present disclosure, in a control device for controlling a three-phase motor, it is possible to accurately detect current detection errors.

[0008] FIG. 7 is a diagram showing an example of a drive system including a control device in embodiment 1. FIG. 8 is a diagram showing an example in which the drive system shown in FIG. 1 is applied to an elevator. FIG. 9 is a diagram showing an example of an error detection unit. FIG. 10 is a diagram showing an example of a correction value calculation unit. FIG. 11 is a diagram showing an example of a three-phase current calculation unit. FIG. 12 is a diagram showing an example of a current control unit. FIG. 13 is a diagram showing another example of a drive system. FIG. 14 is a flowchart showing the order of correction processing performed in the control device. FIG. 15 is a diagram showing an example in which the drive system shown in FIG. 1 is applied to an elevator. FIG. 16 is a diagram showing examples of a power conversion unit and a current detection unit. FIG. 17 is a diagram for explaining the function of a first error detection processing unit. FIG. 18 is a diagram showing another example of a drive system. FIG. 19 is a diagram for explaining the function of a modulation unit. FIG. 19 is a diagram showing an example of hardware resources of a control device.

[0009] The following detailed description will be given with reference to the drawings. Duplicate descriptions will be simplified or omitted as appropriate. In each drawing, the same reference numerals indicate the same or corresponding parts.

[0010] Embodiment 1. Fig. 1 is a diagram showing an example of a drive system including a control device 200 according to embodiment 1. The drive system includes a three-phase motor 1 and the control device 200. As one example, the three-phase motor 1 is a motor for driving an elevator car. As another example, the three-phase motor 1 is a motor used in electric power steering. The three-phase motor 1 may also be a motor used for other purposes.

[0011] The control device 200 controls the three-phase motor 1. The control device 200 includes a current control unit 2, a dq-to-three-phase conversion unit 3, a three-phase-to-dq conversion unit 4, a power conversion unit 5, a current detection unit 6, a rotation detection unit 7, an angular velocity calculation unit 8, a three-phase current calculation unit 9, and a first error detection processing unit 10.

[0012] The power conversion unit 5 converts the power supplied from the power source into power for driving the three-phase motor 1. The power conversion unit 5 supplies the converted power to the three-phase motor 1. The three-phase motor 1 includes a U phase, a V phase, and a W phase. In FIG. 1 , iu indicates a current flowing through the U phase of the three-phase motor 1. iv indicates a current flowing through the V phase of the three-phase motor 1. iw indicates a current flowing through the W phase of the three-phase motor 1.

[0013] The current detection unit 6 detects the value of the current flowing through each phase of the three-phase motor 1. That is, the current detection unit 6 detects the value of the current flowing through the U phase, the V phase, and the W phase of the three-phase motor 1. Hereinafter, the value of the current flowing through the U phase detected by the current detection unit 6 will also be referred to as the current detection value ius. The value of the current flowing through the V phase detected by the current detection unit 6 will also be referred to as the current detection value ivs. The value of the current flowing through the W phase detected by the current detection unit 6 will also be referred to as the current detection value iws.

[0014] The rotation detector 7 detects the electrical angle of the three-phase motor 1. Hereinafter, the electrical angle of the three-phase motor 1 detected by the rotation detector 7 will also be referred to as the electrical angle θre.

[0015] The first error detection processing unit 10 performs processing necessary to correct the current detection error. The current detection error is an error caused by the current detection and included in the value of the current detected by the current detection unit 6. The current detection error is also called a current sensor error.

[0016] The first error detection processing unit 10 detects a current detection error. The current detection error appears as a 1f oscillation in the zero-phase current of the three-phase motor 1. On the other hand, the zero-phase current is not affected by the magnetic circuit error. Therefore, the first error detection processing unit 10 detects the current detection error using the zero-phase current, more specifically, based on the amplitude of the 1f oscillation of the zero-phase current. Note that the magnetic circuit error is an error contained in the value of the current detected by the current detection unit 6 and is caused by the resistance of the three-phase motor 1 and impedance such as inductance. Furthermore, 1f means a frequency that is one time the fundamental frequency f, and 2f, which will be described later, means a frequency that is twice the fundamental frequency f.

[0017] The first error detection processing unit 10 calculates the value of the zero-phase current based on the value of the current of each phase detected by the current detection unit 6. The first error detection processing unit 10 detects the interphase gain error of the current detection unit 6 as a current detection error based on the calculated value of the zero-phase current. The three-phase current calculation unit 9 corrects the value of the current of each phase detected by the current detection unit 6 based on the interphase gain error detected by the first error detection processing unit 10.

[0018] For example, the first error detection processing unit 10 calculates the value of the zero-phase current based on the current detection value ius, the current detection value ivs, and the current detection value iws. Furthermore, the first error detection processing unit 10 detects the inter-phase gain error er_ivs of the V phase relative to the U phase, with the U phase as the reference, based on the calculated value of the zero-phase current. Similarly, the first error detection processing unit 10 detects the inter-phase gain error er_iws of the W phase relative to the U phase, with the U phase as the reference, based on the calculated value of the zero-phase current. The reference phase does not have to be the U phase.

[0019] In the example shown in the present embodiment, the first error detection processing unit 10 further calculates a gain correction value to reduce the detected inter-phase gain error. That is, the first error detection processing unit 10 calculates a gain correction value that reduces the amplitude of the 1f oscillation of the zero-phase current, preferably to zero. In the above example using the U phase as the reference, the first error detection processing unit 10 calculates a gain correction value cor_ivs for the current detection value ivs and a gain correction value cor_iws for the current detection value iws.

[0020] The three-phase current calculation unit 9 calculates the value of the current flowing through each phase of the three-phase motor 1 based on the value of the current of each phase detected by the current detection unit 6 and the gain correction value calculated by the first error detection processing unit 10. In other words, the three-phase current calculation unit 9 corrects the value of the current of each phase detected by the current detection unit 6 using the gain correction value calculated by the first error detection processing unit 10.

[0021] Hereinafter, the value of the current flowing through the U phase calculated by the three-phase current calculation unit 9 will also be referred to as the calculated current value i'u. The value of the current flowing through the V phase calculated by the three-phase current calculation unit 9 will also be referred to as the calculated current value i'v. The value of the current flowing through the W phase calculated by the three-phase current calculation unit 9 will also be referred to as the calculated current value i'w. Note that in the above example using the U phase as the reference, the detected current value ius and the calculated current value i'u are the same value. For this reason, below, the calculated current value i'u will also be referred to as the calculated current value ius.

[0022] The current control unit 2 calculates a voltage command value for the power conversion unit 5 based on a current command value, which is a current control input, and the current values ​​of each phase calculated (corrected) by the three-phase current calculation unit 9. In the example shown in this embodiment, a d-axis current command value id* and a q-axis current command value iq* are input to the current control unit 2 as current command values. Furthermore, a d-axis voltage command value vd* and a q-axis voltage command value vq* are output from the current control unit 2 as voltage command values. For this reason, a three-phase-dq conversion unit 4 is provided between the three-phase current calculation unit 9 and the current control unit 2, and a dq-three-phase conversion unit 3 is provided between the three-phase current calculation unit 9 and the power conversion unit 5.

[0023] The three-phase-dq conversion unit 4 calculates the d-axis current value id and the q-axis current value iq based on the current values ​​of each phase calculated by the three-phase current calculation unit 9 and the electrical angle θre detected by the rotation detection unit 7.

[0024] The angular velocity calculation unit 8 calculates the angular velocity ωre from the electrical angle θre.

[0025] The current control unit 2 receives as input the d-axis current value id, the q-axis current value iq, the angular velocity ωre, the d-axis current command value id*, and the q-axis current command value iq*. Based on these inputs, the current control unit 2 calculates a d-axis voltage command value vd* and a q-axis voltage command value vq*. For example, the current control unit 2 generates a command value vd*, which is a control variable for the power conversion unit 5, based on the difference between the d-axis current command value id* and the actual value id. The current control unit 2 generates a command value vq*, which is a control variable for the power conversion unit 5, based on the difference between the q-axis current command value iq* and the actual value iq.

[0026] The dq-three-phase conversion unit 3 calculates voltage command values ​​for each phase of the three-phase motor 1 based on the d-axis voltage command value vd*, the q-axis voltage command value vq*, and the electrical angle θre. Hereinafter, the command value for the U-phase voltage calculated by the dq-three-phase conversion unit 3 will also be referred to as command value vu*. The command value for the V-phase voltage calculated by the dq-three-phase conversion unit 3 will also be referred to as command value vv*. The command value for the W-phase voltage calculated by the dq-three-phase conversion unit 3 will also be referred to as command value vw*.

[0027] The power conversion unit 5 supplies the required power to the three-phase motor 1 based on the command values ​​vu*, vv*, and vw*.

[0028] Next, the function of the first error detection processing unit 10 will be described in detail.

[0029] The zero-phase current is insensitive to magnetic circuit errors. On the other hand, current detection errors affect the zero-phase current as 1f oscillations. Therefore, the first error detection processing unit 10 detects current detection errors by utilizing the 1f oscillations of the zero-phase current.

[0030] The zero-phase current iz is defined as shown in Equation 1.

[0031]

[0032] As an example, the detection gain when the current detector 6 detects the value of the current flowing through the U-phase is used as the reference. In this case, the current detection value ius is expressed as in Equation 2.

[0033]

[0034] Furthermore, if the current detection error of the V phase is γ, the current detection value ivs is expressed as in Equation 3.

[0035]

[0036] If the current detection error of the W phase is δ, the current detection value iws is expressed as in Equation 4.

[0037]

[0038] Substituting Equation 2-4 into Equation 1 to find the zero-phase current iz gives Equation 5.

[0039]

[0040] From Equation 5, the zero-phase current iz is defined as the sum of a term obtained by multiplying the V-phase current detection error γ by the value of the V-phase current and a term obtained by multiplying the W-phase current detection error δ by the value of the W-phase current. In other words, the zero-phase current iz is defined as the sum of a term synchronized with the V-phase current and a term synchronized with the W-phase current.

[0041] Because the V-phase current and the W-phase current are defined as sine waves, which are periodic functions, there are periods when the currents periodically become zero. Therefore, by sampling the zero-phase current when the V-phase electrical angle is 0 or π [rad], the W-phase current detection error δ can be accurately detected. Similarly, by sampling the zero-phase current when the W-phase electrical angle is 0 or π [rad], the V-phase current detection error γ can be accurately detected. This means that even if the current detection errors δ and γ occur simultaneously, the current detection errors δ and γ can be detected separately.

[0042] For example, consider the timing of ωt=2π / 3, when the W-phase current becomes 0. The zero-phase current iz at this timing is expressed by Equation 6.

[0043]

[0044] Equation 7 can be obtained from Equation 6.

[0045]

[0046] On the right side of Equation 7, iz(2π / 3) is the value of the zero-phase current at the timing when the W-phase current becomes 0. The current detection error γ can be obtained by multiplying iz(2π / 3) by a constant, specifically by (−6 / A√3).

[0047] Similarly, when the V-phase current becomes 0, ωt=π / 3, the equation 8 can be obtained.

[0048] On the right side of Equation 8, iz(π / 3) is the value of the zero-phase current at the timing when the V-phase current becomes 0. The current detection error δ can be obtained by multiplying iz(π / 3) by a constant, specifically by (−6 / A√3).

[0049] In this way, by using the 1f oscillation of the zero-phase current, it is possible to accurately detect the current detection error without being affected by the magnetic circuit error.

[0050] Fig. 2 is a diagram showing an example in which the drive system shown in Fig. 1 is applied to an elevator. That is, a control device 200 controls a three-phase motor 1 for driving the elevator car.

[0051] In the example shown in FIG. 2 , the current detection unit 6 includes a DC-CT (direct current sensor) and an AD converter for each phase of the three-phase motor 1. For example, the current detection unit 6 detects the value of the U-phase current using the DC-CT 6a1 and performs AD conversion on the detected value using the AD converter 6b1. The AD-converted value is output from the current detection unit 6 as a current detection value ius. The current detection unit 6 detects the value of the V-phase current using the DC-CT 6a2 and performs AD conversion on the detected value using the AD converter 6b2. The AD-converted value is output from the current detection unit 6 as a current detection value ivs. The current detection unit 6 detects the value of the W-phase current using the DC-CT 6a3 and performs AD conversion on the detected value using the AD converter 6b3. The AD-converted value is output from the current detection unit 6 as a current detection value iws.

[0052] In the example shown in FIG. 2 , the first error detection processing unit 10 includes an error detection unit 11 and a correction value calculation unit 12 .

[0053] 3 is a diagram showing an example of the error detection unit 11. The error detection unit 11 includes an adder 13, a first coefficient unit 14, a second coefficient unit 15, a phase determination unit 16, a first sample-and-hold unit 17, and a second sample-and-hold unit 18.

[0054] The adder 13 adds the current detection value ius, the current detection value ivs, and the current detection value iws. The first coefficient unit 14 multiplies the addition result from the adder 13 by a coefficient C1 and outputs the result. The coefficient C1 is a value corresponding to (-6 / A√3) on the right side of Equation 7. The second coefficient unit 15 multiplies the addition result from the adder 13 by a coefficient C2 and outputs the result. The coefficient C2 is a value corresponding to (-6 / A√3) on the right side of Equation 8.

[0055] The phase determination unit 16 determines the phase based on the current detection value ius, the current detection value ivs, and the current detection value iws. The phase determination unit 16 determines the timing when the W-phase electrical angle is 0 or π [rad], i.e., the zero-cross timing of the W-phase current. The zero-cross timing of the W-phase current is the detection timing of the V-phase current detection error γ. The phase determination unit 16 outputs a timing signal t_v at the zero-cross timing of the W-phase current. The phase determination unit 16 determines the timing when the V-phase electrical angle is 0 or π [rad], i.e., the zero-cross timing of the V-phase current. The zero-cross timing of the V-phase current is the detection timing of the W-phase current detection error δ. The phase determination unit 16 outputs a timing signal t_w at the zero-cross timing of the V-phase current.

[0056] When the timing signal t_v is input from the phase determination unit 16, the first sample-and-hold unit 17 outputs the value output from the first coefficient unit 14 as the interphase gain error er_ivs. That is, the error detection unit 11 detects the interphase gain error er_ivs based on the value of the zero-phase current when the W-phase current crosses zero. When the timing signal t_w is input from the phase determination unit 16, the second sample-and-hold unit 18 outputs the value output from the second coefficient unit 15 as the interphase gain error er_iws. That is, the error detection unit 11 detects the interphase gain error er_iws based on the value of the zero-phase current when the V-phase current crosses zero.

[0057] 4 is a diagram showing an example of the correction value calculation unit 12. The correction value calculation unit 12 includes a first calculation unit 19 and a second calculation unit 20. The inter-phase gain error er_ivs from the error detection unit 11 is input to the first calculation unit 19. The first calculation unit 19 multiplies the input value by 1 / (1 + input value) based on Equation 3, and outputs the result as the gain correction value cor_ivs. The inter-phase gain error er_iws from the error detection unit 11 is input to the second calculation unit 20. The second calculation unit 20 multiplies the input value by 1 / (1 + input value) based on Equation 4, and outputs the result as the gain correction value cor_iws.

[0058] FIG. 5 is a diagram showing an example of the three-phase current calculation unit 9. The three-phase current calculation unit 9 includes a multiplication unit 21 and a multiplication unit 22. The multiplication unit 21 multiplies the current detection value ivs by the gain correction value cor_ivs and outputs the result as the calculated current value i'v. The multiplication unit 22 multiplies the current detection value iws by the gain correction value cor_iws and outputs the result as the calculated current value i'w. Note that FIG. 5 shows an example in which the U phase is used as the reference. Therefore, the three-phase current calculation unit 9 outputs the input current detection value ius as the calculated current value ius without modification.

[0059] 6 is a diagram illustrating an example of the current control unit 2. The current control unit 2 includes a subtraction unit 23, a subtraction unit 24, a d-axis current control unit 25, a q-axis current control unit 26, a decoupling control unit 27, an adder unit 28, and an adder unit 29.

[0060] The subtractor 23 outputs the difference id_er between the d-axis current command value id* and the d-axis current value id. The d-axis current control unit 25 calculates the d-axis voltage command value vd** based on the difference id_er. The subtractor 24 outputs the difference iq_er between the q-axis current command value iq* and the q-axis current value iq. The q-axis current control unit 26 calculates the q-axis voltage command value vq** based on the difference iq_er.

[0061] The decoupling control unit 27 performs decoupling processing to cancel out interference between the d and q axes. An adder 28 adds together the command value vd** from the d-axis current control unit 25 and the correction value output from the decoupling control unit 27, and the resulting value is output from the current control unit 2 as the command value vd* for the d-axis voltage. An adder 29 adds together the command value vq** from the q-axis current control unit 26 and the correction value output from the decoupling control unit 27, and the resulting value is output from the current control unit 2 as the command value vq* for the q-axis voltage.

[0062] Fig. 7 is a diagram showing another example of a drive system. The example shown in Fig. 7 differs from the example shown in Fig. 1 in that the control device 200 further includes a second error detection processing unit 30. The second error detection processing unit 30 performs processing required to correct the magnetic circuit error. The second error detection processing unit 30 detects the magnetic circuit error based on the current values ​​of each phase calculated (corrected) by the three-phase current calculation unit 9.

[0063] As described above, the three-phase current calculation unit 9 corrects the values ​​of the currents of each phase detected by the current detection unit 6 using the gain correction value calculated by the first error detection processing unit 10. Therefore, the current detection errors are excluded from the calculated current value ius, calculated current value i'v, and calculated current value i'w, which are outputs from the three-phase current calculation unit 9. The second error detection processing unit 30 detects the magnetic circuit error using these values ​​after the current detection error correction process has been completed. The 2f vibration of the d-axis current, which is the input to the second error detection processing unit 30, has been corrected and no longer contains any vibration caused by the current detection error, and only contains the 2f vibration caused by the magnetic circuit error, allowing for accurate detection of the magnetic circuit error.

[0064] 8 is a flowchart showing the sequence of correction processes performed by the control device 200. As shown in FIG. 8, the control device 200 performs a process of correcting the current detection error using the zero-phase current (S101), and then a process of correcting the magnetic circuit error (S102). Note that the control device 200 may perform both a learning process for the current detection error and a learning process for the magnetic circuit error. In such a case, the control device 200 performs the learning process for the current detection error and then the learning process for the magnetic circuit error.

[0065] In the example shown in this embodiment, a three-phase-dq conversion unit 4 is provided between the three-phase current calculation unit 9 and the current control unit 2. Therefore, the second error detection processing unit 30 uses the d-axis current value id to detect the magnetic circuit error. For example, the second error detection processing unit 30 detects the magnetic circuit error based on the amplitude of 2f vibration of the d-axis current. As another example, the second error detection processing unit 30 may use the q-axis current value iq to detect the magnetic circuit error. For example, the second error detection processing unit 30 detects the magnetic circuit error based on the amplitude of 2f vibration of the q-axis current. The second error detection processing unit 30 may detect the magnetic circuit error by other methods. The power conversion unit 5 supplies power to the three-phase motor 1 based also on the magnetic circuit error detected by the second error detection processing unit 30.

[0066] Fig. 9 is a diagram showing an example in which the drive system shown in Fig. 7 is applied to an elevator. In the example shown in Fig. 9, the second error detection processing unit 30 includes an error detection unit 31 and a correction value calculation unit 32. Of the functions included in the control device 200, functions that are not related to the second error detection processing unit 30 are the same as those in the example shown in Fig. 2. In the example shown in Fig. 9, each of the examples shown in Figs. 3 to 6 may be adopted.

[0067] The error detection unit 31 detects a magnetic circuit parameter error er_zv of the V phase relative to the U phase based on the d-axis current value id and the electrical angle θre. Similarly, the error detection unit 31 detects a magnetic circuit parameter error er_zw of the W phase relative to the U phase based on the d-axis current value id and the electrical angle θre. Note that the reference phase does not have to be the U phase.

[0068] The correction value calculation unit 32 calculates parameter correction values ​​to reduce the detected magnetic circuit parameter errors. That is, the correction value calculation unit 32 calculates parameter correction values ​​that reduce the amplitude of the 2f vibration of the d-axis current, preferably to zero. In the above example using the U-phase as the reference, the correction value calculation unit 32 calculates a parameter correction value cor_zv for the command value vv* and a parameter correction value cor_zw for the command value vw*.

[0069] The power conversion unit 5 supplies the required power to the three-phase motor 1 based on the command value vu*, the value obtained by correcting the command value vv* with the parameter correction value cor_zv, and the value obtained by correcting the command value vw* with the parameter correction value cor_zw.

[0070] Next, an example in which the present drive system is applied to an electric power steering system will be described. The following example may be adopted in any of the above-mentioned examples if applicable.

[0071] Fig. 10 is a diagram illustrating an example of the power conversion unit 5 and the current detection unit 6. In the example illustrated in Fig. 10, the power conversion unit 5 includes a smoothing capacitor 34 and an inverter circuit 35. The smoothing capacitor 34 smoothes the DC voltage from the DC power supply. The inverter circuit 35 converts the DC voltage smoothed by the smoothing capacitor 34 into an AC voltage.

[0072] The inverter circuit 35 includes a plurality of switching elements for each phase of the three-phase motor 1. For example, the inverter circuit 35 includes an upper arm switching element Sup and a lower arm switching element Sun for supplying power to the U phase. The U phase switching elements Sup and Sun are connected in series.

[0073] The inverter circuit 35 includes an upper arm switching element Svp and a lower arm switching element Svn for supplying power to the V phase. The V phase switching element Svp and switching element Svn are connected in series. The inverter circuit 35 includes an upper arm switching element Swp and a lower arm switching element Swn for supplying power to the W phase. The W phase switching element Swp and switching element Swn are connected in series.

[0074] The current detection unit 6 includes a shunt resistor for detecting current for each phase of the three-phase motor 1. For example, the current detection unit 6 includes a shunt resistor Ru for the U phase, a shunt resistor Rv for the V phase, and a shunt resistor Rw for the W phase. The shunt resistor Ru is connected in series with the switching element Sun such that the switching element Sun is disposed between the switching element Sup and the shunt resistor Ru.

[0075] The shunt resistor Rv is connected in series with the switching element Svn such that the switching element Svn is disposed between the switching element Svp and the shunt resistor Rv. The shunt resistor Rw is connected in series with the switching element Swn such that the switching element Swn is disposed between the switching element Swp and the shunt resistor Rw.

[0076] 11 is a diagram for explaining the function of the first error detection processing unit 10. FIG. 11 shows the value of the voltage (duty ratio) applied to the three-phase motor 1.

[0077] In a drive system, the current detection unit 6 cannot always detect current. For example, an upper limit L of the duty ratio at which current can be detected is predetermined. That is, when the value of the U-phase voltage exceeds the upper limit L, the current detection unit 6 cannot detect the value of the U-phase current. When the value of the V-phase voltage exceeds the upper limit L, the current detection unit 6 cannot detect the value of the V-phase current. When the value of the W-phase voltage exceeds the upper limit L, the current detection unit 6 cannot detect the value of the W-phase current. In Figure 11, sections K1, K2, and K3 indicate sections in which the current detection unit 6 can detect the values ​​of all three-phase currents.

[0078] The first error detection processing unit 10 calculates the value of the zero-phase current if the voltage command value of each phase for the power conversion unit 5 is equal to or less than the threshold value TH1. That is, the first error detection processing unit 10 calculates the zero-phase current if each of the command value vu*, command value vv*, and command value vw* is equal to or less than the threshold value TH1. The first error detection processing unit 10 does not calculate the value of the zero-phase current if any one of the command value vu*, command value vv*, and command value vw is greater than the threshold value TH1. This prevents the zero-phase current from being calculated when the current detection value ius, current detection value ivs, or current detection value iws has not been detected.

[0079] The threshold value TH1 is set in advance based on the upper limit value L. The threshold value TH1 may be a value that matches the upper limit value L. The threshold value TH1 may also be set to a value that is smaller than the upper limit value L to allow for some margin.

[0080] Fig. 12 is a diagram showing another example of a drive system. The example shown in Fig. 12 differs from the example shown in Fig. 7 in that the control device 200 further includes a modulator 33. The modulator 33 is provided between the dq-three-phase converter 3 and the power converter 5. The modulator 33 modulates the voltage command value from the dq-three-phase converter 3 and outputs the modulated voltage command value to the power converter 5.

[0081] For example, the modulator 33 modulates the command value vu* to a command value vu2*. The modulator 33 modulates the command value vv* to a command value vv2*. The modulator 33 modulates the command value vw* to a command value vw2*. The power converter 5 supplies the required power to the three-phase motor 1 based on the command value vu2*, the command value vv2*, and the command value vw2*.

[0082] As described above, for example, if the value of the U-phase voltage exceeds the upper limit value L, the current detection unit 6 cannot detect the value of the U-phase current. The modulation unit 33 performs modulation so as to widen the range in which the current detection unit 6 can detect the current. Preferably, the modulation unit 33 performs modulation so that the current detection unit 6 can always detect the current. That is, the modulation unit 33 modulates the voltage command value of each phase for the power conversion unit 5 so that the voltage command value is always equal to or less than the threshold value TH1.

[0083] FIG. 13 is a diagram illustrating the function of the modulator 33. FIG. 13 shows an example of a voltage command value modulated by the modulator 33. The modulator 33 calculates an offset value based on the command value vu*, command value vv*, and command value vw*. As an example, the offset value is the smallest value among the command value vu*, command value vv*, and command value vw*. The modulator 33 obtains the command value vu2*, command value vv2*, and command value vw2* by equally superimposing the offset value on the command value vu*, command value vv*, and command value vw*.

[0084] In this example, the voltage difference between each phase of the three-phase motor 1 remains unchanged before and after modulation. Therefore, the three-phase motor 1 operates in the same manner when the pre-modulation voltage command value is input to the power conversion unit 5 and when the modulated voltage command value is input to the power conversion unit 5. In other words, in this example, the range in which the current detection unit 6 can detect the current can be expanded without changing the operation of the three-phase motor 1.

[0085] 14 is a diagram illustrating an example of hardware resources of the control device 200. The control device 200 includes, as hardware resources, a processing circuit 40 including a processor 41 and a memory 42. The processing circuit 40 may include multiple processors 41. The processing circuit 40 may include multiple memories 42.

[0086] In this embodiment, the units denoted by the reference numerals 2 to 33 indicate functions possessed by the control device 200. The functions of the units denoted by the reference numerals 2 to 33 can be realized by software written as a program, firmware, or a combination of software and firmware. The program is stored in a memory 42. The control device 200 realizes the functions of the units denoted by the reference numerals 2 to 33 by executing the program stored in the memory 42 using a processor 41 (computer).

[0087] The processor 41 is also called a CPU (Central Processing Unit), central processing unit, processing unit, arithmetic unit, microprocessor, microcomputer, or DSP. The memory 42 may be a semiconductor memory, a magnetic disk, a flexible disk, an optical disk, a compact disk, a minidisk, or a DVD. Usable semiconductor memories include RAM, ROM, flash memory, EPROM, and EEPROM.

[0088] Fig. 15 is a diagram showing another example of hardware resources of the control device 200. In the example shown in Fig. 15, the control device 200 includes a processing circuit 40 including a processor 41, a memory 42, and dedicated hardware 43. Fig. 15 shows an example in which some of the functions of the control device 200 are realized by the dedicated hardware 43. All of the functions of the control device 200 may be realized by the dedicated hardware 43. The dedicated hardware 43 may be a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

[0089] The control device according to the present disclosure can be applied to a device for controlling a three-phase motor.

[0090] REFERENCE SIGNS LIST 1 Three-phase motor, 2 Current control section, 3 dq-to-three-phase conversion section, 4 Three-phase-dq conversion section, 5 Power conversion section, 6 Current detection section, 7 Rotation detection section, 8 Angular velocity calculation section, 9 Three-phase current calculation section, 10 First error detection processing section, 11 Error detection section, 12 Correction value calculation section, 13 Addition section, 14 First coefficient section, 15 Second coefficient section, 16 Phase determination section, 17 First sample-hold section, 18 Second sample-hold section, 19 First calculation section, 20 Second calculation section, 21 Multiplication section, 22 Multiplication section, 23 Subtraction section, 24 Subtraction section, 25 d-axis current control section, 26 q-axis current control section, 27 Decoupling control section, 28 Addition section, 29 Addition section, 30 Second error detection processing section, 31 Error detection unit, 32 correction value calculation unit, 33 modulation unit, 34 smoothing capacitor, 35 inverter circuit, 40 processing circuit, 41 processor, 42 memory, 43 dedicated hardware, 200 control device Sup, Svp, Swp, Sun, Svn, Swn switching elements Ru, Rv, Rw shunt resistor

Claims

1. a power conversion unit that supplies power to the three-phase motor; a current detection unit that detects the value of a current flowing through each phase of the three-phase motor; a first error detection processing unit that calculates a zero-phase current value based on the current values ​​of the phases detected by the current detection unit, and detects a phase-to-phase gain error of the current detection unit based on the calculated zero-phase current value; a three-phase current calculation unit that corrects the value of the current of each phase detected by the current detection unit based on the inter-phase gain error detected by the first error detection processing unit; a current control unit that calculates a voltage command value for the power conversion unit based on a current command value and the current values ​​of the phases corrected by the three-phase current calculation unit; A control device comprising:

2. the first error detection processing unit calculates a gain correction value for reducing the detected inter-phase gain error; 2. The control device according to claim 1, wherein the three-phase current calculation unit corrects the current values ​​of the phases detected by the current detection unit using the gain correction value calculated by the first error detection processing unit.

3. the three-phase motor includes a first phase, a second phase, and a third phase; The first error detection processing unit detecting an inter-phase gain error of the third phase relative to the first phase based on a value of the zero-phase current when the current of the second phase crosses zero; 3. The control device according to claim 1, wherein an interphase gain error of the second phase relative to the first phase is detected based on a value of a zero-phase current when the current of the third phase crosses zero.

4. a second error detection processing unit that detects a magnetic circuit error of the three-phase motor based on the current values ​​of the phases corrected by the three-phase current calculation unit; 3. The control device according to claim 1, wherein the power conversion unit supplies power to the three-phase motor based on the magnetic circuit error detected by the second error detection processing unit.

5. The power conversion unit, for each phase of the three-phase motor, a first switching element of the upper arm; a second switching element of a lower arm connected in series to the first switching element; Equipped with the current detection unit includes a shunt resistor for each phase of the three-phase motor, 3. The control device according to claim 1, wherein the shunt resistor is connected in series with the second switching element such that the second switching element is disposed between the first switching element and the shunt resistor.

6. 3. The control device according to claim 1, wherein the first error detection processing unit calculates a value of a zero-phase current when a voltage command value for each phase to the power conversion unit is equal to or smaller than a preset threshold value.

7. 3. The control device according to claim 1, further comprising a modulation unit that modulates a voltage command value of each phase for the power conversion unit so that the voltage command value of each phase is equal to or less than a preset threshold value without changing a voltage difference between each phase of the three-phase motor.