Control device for rotary machine

Abstract

A control device for a rotary machine comprises: a current command generation unit; a field winding voltage command unit; and a stator winding voltage command unit. The current command generation unit (81) includes: a current command calculation unit (810) that calculates a field winding current command and a stator winding current command on the basis of an operation command and a DC voltage; an allowable flux calculation unit (811) that calculates an allowable flux interlinking with a stator winding, the allowable flux being calculated on the basis of the rotation speed, the DC voltage, the stator winding current command, and the field winding current; a first flux-weakening current calculation unit (812) that calculates a first flux-weakening current on the basis of the field winding current, the stator winding current command, and the allowable flux; and a final current command calculation unit (813) that calculates a final stator winding current command on the basis of the stator winding current command and the first flux-weakening current.

Description

Rotating machine control device

[0001] The present application relates to a control device for a rotating machine.

[0002] A control device for a rotating machine having a field winding and a stator winding generates current commands for the currents flowing through the field winding and the stator winding in response to externally input operational commands such as torque and rotational speed of the rotating machine. Such a control device for a rotating machine controls the currents flowing through the field winding and the stator winding so that they follow the current commands. It is known that, because the impedance of the field winding is generally greater than the impedance of the stator winding, the response of the current flowing through the field winding is slower than the response of the current flowing through the stator winding. Therefore, in order to appropriately control the rotating machine, conventional control devices for rotating machines perform control that takes into account the fact that the current response of the field winding is slower than the current response of the stator winding.

[0003] A conventional method for controlling a rotating machine is disclosed in which a current command for a stator winding is calculated based on torque variations caused by variations in the delay in the current response of the field winding (see, for example, Patent Document 1). Another control method is disclosed in which a response delay of the field winding current to a current command is simulated, and a current command for the stator winding is calculated based on the simulated response delay (see, for example, Patent Document 2).

[0004] JP 2022-83905 A International Publication No. 2020 / 217438

[0005] However, with conventional rotating machine control methods, if the delay in the field winding current response is slower than expected, or if the current actually flowing through the stator winding cannot follow the stator winding current command due to variations in specifications, the amplitude of the stator winding current command may become larger than expected. In this case, if the amplitude of the stator winding current command exceeds the upper limit of the voltage that the control device can output, the voltage command may become saturated. Saturation of the voltage command may cause windup of the integral control in the control device and unintended magnetic flux interference between the stator winding and field winding in the rotating machine. As a result, there is a problem of destabilizing the current control for the rotating machine.

[0006] The present application has been made to solve the above-mentioned problems, and aims to provide a control device for a rotating machine that can suppress saturation of the voltage command for the stator winding and perform stable current control even when there is a possibility that the amplitude of the current command for the stator winding will be larger than expected.

[0007] The control device for a rotating machine of the present application is a control device for a rotating machine equipped with a rotor having a field winding and a stator having a stator winding, and includes: a current command generation unit that generates a field winding current command for the field winding current and a stator winding current command for the stator winding current based on an operation command input from outside; a field winding voltage command unit that generates a field winding voltage command for a voltage to be applied to the field winding based on the field winding current command; a stator winding voltage command unit that generates a stator winding voltage command for a voltage to be applied to the stator winding based on the stator winding current command; a field winding power conversion unit that applies a voltage to the field winding based on the field winding voltage command; and a stator winding power conversion unit that applies a voltage to the stator winding based on the stator winding voltage command. The current command generation unit includes a current command calculation unit that calculates a field winding current command and a stator winding current command based on the operation command and a DC voltage input from outside; an allowable magnetic flux calculation unit that calculates an allowable magnetic flux, which is an allowable value of magnetic flux linking the stator winding, based on the rotational speed of the rotating machine, the DC voltage, the stator winding current command, and the field winding current; a first flux-weakening current calculation unit that calculates a first flux-weakening current based on the field winding current, the stator winding current command, and the allowable magnetic flux; and a final current command calculation unit that calculates a final stator winding current command based on the stator winding current command and the first flux-weakening current.

[0008] In the control device for a rotating machine of the present application, the current command generation unit includes a current command calculation unit that calculates a field winding current command and a stator winding current command based on an operation command and a DC voltage input from outside, an allowable magnetic flux calculation unit that calculates an allowable magnetic flux, which is an allowable value of magnetic flux linking the stator winding, based on the rotational speed of the rotating machine, the DC voltage, the stator winding current command, and the field winding current, a first flux-weakening current calculation unit that calculates a first flux-weakening current based on the field winding current, the stator winding current command, and the allowable magnetic flux, and a final current command calculation unit that calculates a final stator winding current command based on the stator winding current command and the first flux-weakening current, so that saturation of the voltage command for the stator winding can be suppressed and stable current control can be performed.

[0009] 1 is a configuration diagram of a control device for a rotating machine according to embodiment 1. FIG. 2 is a configuration diagram of a stator winding power conversion unit according to embodiment 1. FIG. 3 is a configuration diagram of a field winding power conversion unit according to embodiment 1. FIG. 4 is a configuration diagram of a field winding power conversion unit according to embodiment 1. FIG. 5 is a configuration diagram showing functions of a processor according to embodiment 1. FIG. 6 is a configuration diagram showing functions of a current command generation unit according to embodiment 1. FIG. 7 is a diagram showing a relationship of q-axis magnetic flux with respect to d-axis current and q-axis current in a certain specific field winding current of the rotating machine according to embodiment 1. FIG. 8 is a diagram showing a relationship of d-axis current with respect to d-axis magnetic flux and q-axis current in a certain specific field winding current of the rotating machine according to embodiment 1. FIG. 9 is a configuration diagram showing functions of a current command generation unit according to embodiment 2.

[0010] Hereinafter, a control device for a rotating machine according to an embodiment of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

[0011] Embodiment 1. Fig. 1 is a configuration diagram of a rotating machine control device according to embodiment 1. The rotating machine control device 1 of this embodiment controls a rotating machine 2. The control device 1 is driven by a DC voltage from an external DC power supply 3. The control device 1 includes a stator winding power conversion unit 4, a field winding power conversion unit 5, a stator winding current detection unit 6 that detects a current flowing in the stator winding, a field winding current detection unit 7 that detects a current flowing in the field winding, a processor 8, and a storage device 9. The rotating machine control device 1 of this embodiment controls the rotating machine 2 based on an operation command input from a higher-level device. The operation command input from the higher-level device is, for example, a torque command that determines the torque of the rotating machine 2, a rotational speed command that determines the rotational speed, etc.

[0012] The rotating machine 2 includes a rotor having a permanent magnet and a field winding, and a stator having a set of three-phase stator windings consisting of U-phase, V-phase, and W-phase. However, the rotor does not have to have a permanent magnet. Furthermore, the stator winding is not limited to a three-phase set, but may have three or more phases and one or more sets.

[0013] The stator winding power converter 4 converts the DC voltage of the DC power supply 3 into an AC voltage and applies the AC voltage to the stator winding. The field winding power converter 5 converts the DC voltage of the DC power supply 3 into a DC voltage with a different amplitude and applies this DC voltage to the field winding as a field winding voltage V ｆ The stator winding current detection unit 6 detects the currents flowing in the U-phase, V-phase, and W-phase stator windings of the rotating machine 2. The field winding current detection unit 7 detects the currents flowing in the field windings of the rotating machine 2.

[0014] FIG. 2 is a configuration diagram of a stator winding power conversion unit according to this embodiment. FIG. 2 shows an example of the stator winding power conversion unit 4 according to this embodiment. As shown in FIG. 2, the stator winding power conversion unit 4 according to this embodiment is a three-phase full-bridge inverter configured with six switching elements and diodes. This stator winding power conversion unit 4 is configured when the stator winding of the rotating machine has one set of three phases, namely, U-phase, V-phase, and W-phase. The switching elements are configured with MOS-FETs (Metal Oxide Semiconductor-Field Effect Transistors), IGBTs (Insulated Gate Bipolar Transistors), or the like. The stator winding power conversion unit 4 applies AC voltages to the U-phase, V-phase, and W-phase stator windings of the rotating machine 2 in response to stator winding switching commands input from the processor 8. Specifically, the stator winding power conversion unit 4 applies AC voltages according to U-phase switching commands UH, UL, V-phase switching commands VH, VL, and W-phase switching commands WH, WL from the processor 8 to the U-phase, V-phase, and W-phase stator windings of the rotating machine 2. The stator winding power conversion unit 4 is not limited to an inverter and may be a converter. The inverter of the stator winding power conversion unit 4 may be configured with three or more phases and one or more sets according to the number of phases of the stator winding of the rotating machine 2.

[0015] FIG. 3 is a configuration diagram of a field winding power conversion unit according to this embodiment. FIG. 3 shows an example of the field winding power conversion unit 5 according to this embodiment. As shown in FIG. 3, the field winding power conversion unit 5 according to this embodiment is a two-phase full-bridge converter composed of four switching elements and diodes. The switching elements are composed of MOS-FETs, IGBTs, or the like. The field winding power conversion unit 5 applies a DC voltage to the field winding of the rotating machine 2 in accordance with a field winding switching command input from the processor 8. Specifically, the field winding power conversion unit 5 converts the DC voltage input from the DC power supply 3 into DC voltages of different amplitudes in accordance with field winding switching commands F1H, F1L, F2H, and F2L from the processor 8, and applies the DC voltage to the field winding of the rotating machine 2. For example, if the torque command input to the processor 8 is a command to increase the amplitude, the field winding power conversion unit 5 controls the applied voltage so that the current in the field winding increases in the positive direction. Conversely, when the torque command input to the processor 8 is a command to decrease the amplitude, the field winding power conversion unit 5 controls the applied voltage so that the current in the field winding increases in the negative direction.

[0016] FIG. 4 is a configuration diagram of a field winding power converter according to this embodiment. FIG. 4 shows another example of the field winding power converter 5 according to this embodiment. As shown in FIG. 4, this field winding power converter 5 is the same as the field winding power converter shown in FIG. 3 except that the switching elements that apply a negative voltage to the field winding are replaced with diodes. This makes this field winding power converter 5 less expensive than the field winding power converter shown in FIG. 3. However, this field winding power converter 5 is unable to apply a negative voltage to the field winding. Therefore, when the torque command is a command to decrease the amplitude, the current response of the field winding is highly dependent on the time constant of the resistance and inductance of the field winding, and the current response of the field winding is much slower than the current response of the stator winding.

[0017] The stator winding current detection unit 6 and the field winding current detection unit 7 are current sensors, such as resistance detection type and magnetic field detection type. The stator winding current detection unit 6 detects the stator winding current I flowing through the stator windings of the U-phase, V-phase, and W-phase of the rotating machine 2. Ｕ , IＶ , I Ｗ The field winding current detection unit 7 detects the field winding current I ｆ Detect.

[0018] The processor 8 is, for example, a CPU (Central Processing Unit), and executes programs read from the storage device 9 to realize various functions. The programs executed by the processor 8 are stored in the storage device 9. The storage device 9 includes a volatile storage device such as a random access memory and an auxiliary storage device such as a flash memory. When the processor 8 reads a program from the storage device 9, it reads the program stored in the auxiliary storage device via the volatile storage device. The processor 8 may output data such as calculation results to the volatile storage device of the storage device 9, or may save the data in the auxiliary storage device via the volatile storage device.

[0019] 5 is a block diagram showing the functions of the processor 8. As shown in FIG. 5, the processor 8 has a current command generating unit 81, a stator winding voltage command unit 82, a stator winding switching command generating unit 83, a field winding voltage command unit 84, and a field winding switching command generating unit 85.

[0020] The current command generating unit 81 receives operation commands such as a torque command and a rotation speed command, the DC voltage of the DC power supply 3, and the stator winding current I detected by the stator winding current detecting unit 6. Ｕ , I Ｖ , I Ｗ and the field winding current I detected by the field winding current detection unit 7. ｆ Based on these inputs, the current command generating unit 81 generates the final stator winding current command I ｄｔｇｔ , I ｑｔｇｔ and the field winding current command I ｆｒｅｆ Here, the d-axis indicates the direction of the magnetic flux that links to the stator through the rotor's permanent magnet and field winding, and the q-axis indicates the axis perpendicular to the d-axis. Hereinafter, the subscripts d and q in the notation of current and voltage refer to the d-axis and q-axis, respectively.

[0021] The stator winding voltage command unit 82 outputs the final stator winding current command I generated by the current command generation unit 81. ｄｔｇｔ , I ｑｔｇｔ and the stator winding current I detected by the stator winding current detection unit 6. Ｕ , I Ｖ , I Ｗ Based on this, the stator winding voltage command unit 82 generates a stator winding voltage command so that the stator winding current follows the final stator winding current command. Ｕ , I Ｖ , I Ｗ Based on the rotor position information of the rotating machine 2, ｄ , I ｑ Then, we transform the coordinates into ｄ , I ｑ Ga I ｄｔｇｔ , I ｑｔｇｔ The final voltage command V is calculated by using PI (Proportional-Integral) control and non-interference control to follow the ｄｔｇｔ , V ｑｔｇｔ Furthermore, the stator winding voltage command unit 82 calculates V ｄｔｇｔ , V ｑｔｇｔ is the stator winding voltage command V Ｕ , V Ｖ , V Ｗ Although not shown, the rotor position information of the rotating machine 2 can be detected by a resolver, encoder, or the like attached to the rotating machine 2. Alternatively, the rotor position information of the rotating machine 2 may be rotor position information estimated by a rotor position estimator. The rotational speed of the rotating machine 2 can be obtained from the time change of the rotor position information.

[0022] The stator winding switching command generating unit 83 generates the stator winding voltage command V calculated by the stator winding voltage command unit 82. Ｕ , V Ｖ , V ＷBy pulse width modulation of the stator winding voltage command, the stator winding switching command generator 83 generates U-phase switching commands UH, UL, V-phase switching commands VH, VL, and W-phase switching commands WH, WL, each having a pulse width according to the stator winding voltage command. The stator winding switching command generator 83 then outputs the generated switching commands to the stator winding power converter 4.

[0023] The field winding voltage command unit 84 receives the field winding current command I generated by the current command generation unit 81. ｆｒｅｆ and the field winding current I detected by the field winding current detection unit 7. ｆ Based on this, the field winding voltage command is generated so that the field winding current follows the field winding current command. ｆ is the field winding current command I ｆｒｅｆ The field winding voltage command V is set by using PI control to follow the ｆｒｅｆ Calculate the following.

[0024] The field winding switching command generating unit 85 generates the field winding voltage command V calculated by the field winding voltage command unit 84. ｆｒｅｆ By pulse-width modulating the field winding voltage command, the field winding switching command generator 85 generates switching commands having a pulse width corresponding to the field winding voltage command. When the field winding power converter 5 has the configuration shown in FIG. 3 , the field winding switching command generator 85 generates switching commands F1H, F1L and F2H, F2L. When the field winding power converter 5 has the configuration shown in FIG. 4 , the field winding switching command generator 85 generates switching commands F1H, F1L. Then, the field winding switching command generator 85 outputs the generated switching commands to the field winding power converter 5.

[0025] 6 is a block diagram showing the functions of the current command generation unit 81. As shown in FIG. 6, the current command generation unit 81 includes a current command calculation unit 810, an allowable magnetic flux calculation unit 811, a first flux-weakening current calculation unit 812, and a final current command calculation unit 813.

[0026] A torque command, a rotation speed, and a DC voltage are input to the current command calculation unit 810. The current command calculation unit 810 calculates the stator winding current command I that maximizes the efficiency based on the torque command, the rotation speed, and the DC voltage.ｄｒｅｆ , I ｑｒｅｆ and the field winding current command I ｆｒｅｆ The current command calculation unit 810 calculates the stator winding current command I that maximizes the efficiency based on this lookup table. ｄｒｅｆ , I ｑｒｅｆ and the field winding current command I ｆｒｅｆ The current command calculation unit 810 does not necessarily need to generate the stator winding current command and the field winding current command using a look-up table. The current command calculation unit 810 may calculate the stator winding current command and the field winding current command based on a relational expression between the torque command, the rotational speed, the DC voltage, the stator winding current command, and the field winding current command. When a rotational speed command is given as the operation command, the rotational speed command may be used instead of the rotational speed.

[0027] The allowable magnetic flux calculation unit 811 receives the stator winding current command I ｄｒｅｆ , I ｑｒｅｆ , torque command, rotation speed and field winding current I ｆ The allowable magnetic flux calculation unit 811 calculates the stator winding current command, torque command, rotation speed, and field winding current I by using equations (1) to (16) described below. ｆ Based on this, the d-axis component φ of the allowable magnetic flux ｄｌｉｍ Calculate the following.

[0028] The steady-state voltage equation is the d-axis voltage V ｄ , q-axis voltage V ｑ , d-axis current I ｄ , q-axis current I ｑ , d-axis magnetic flux φ ｄ , q-axis magnetic flux φ ｑ and the electrical angular velocity ω, is given by the following equation (1).

[0029]

[0030] d-axis magnetic flux φ ｄ and q-axis magnetic flux φ ｑ As shown in the following equation (2), the d-axis current I ｄ , q-axis current I ｑ and the field winding current I ｆ It can be expressed as a function of

[0031]

[0032] Figure 7 shows the relationship between the d-axis current and the q-axis current and the q-axis magnetic flux for a specific field winding current. Figure 7 shows the relationship between the lower equation of equation (2) for a specific field winding current. As shown in Figure 7, the change in the q-axis magnetic flux with respect to the d-axis current is small, but the change in the q-axis magnetic flux due to the q-axis current is large. Note that although a diagram corresponding to the upper equation of equation (2) is not shown, the change in the d-axis magnetic flux with respect to the q-axis current is small, but the change in the d-axis magnetic flux due to the d-axis current is large.

[0033] DC voltage V output by DC power supply 3 ｄｃ Therefore, the d-axis voltage and the q-axis voltage are limited by the limit voltage V ｍａｘ The sum of the squares of the d-axis voltage and the q-axis voltage must satisfy the following equation (3): In other words, voltage saturation can be suppressed by reducing the absolute value of the second term on the right side of equation (1).

[0034]

[0035] Clamping voltage V ｍａｘ is given by the following equation (4) using the voltage utilization rate K. The voltage utilization rate K is 0.707 when the line voltage is operating at the maximum amplitude at which it can maintain a sine wave, and is 0.78 when a square wave is applied.

[0036]

[0037] Substituting equation (1) into equation (3), the following equation (5) is obtained.

[0038]

[0039] In a region where voltage saturation is a concern, the following equation (6) holds true in many cases.

[0040]

[0041] From equation (5), the upper limits of the d-axis magnetic flux and the q-axis magnetic flux are determined by the clamping voltage. Therefore, as the rotation speed increases, the absolute value of the d-axis magnetic flux or the q-axis magnetic flux must be suppressed. To reduce the absolute value of the d-axis magnetic flux, the d-axis current must be made negative, and to reduce the absolute value of the q-axis magnetic flux, the absolute value of the q-axis current must be made smaller.

[0042] d-axis magnetic flux φ ｄ and q-axis magnetic flux φ ｑ Since varies depending on the d-axis current and q-axis current, the third term of equation (5) is essentially not determined when the d-axis current and q-axis current are in an unstable state. However, since the relationship of equation (6) holds, the virtual d-axis magnetic flux value φ can be calculated from the d-axis current command and q-axis current command using the following equation (7): ｄ＿ｔｍｐ and the q-axis magnetic flux virtual value φ ｑ＿ｔｍｐ The virtual d-axis magnetic flux value φ as shown in Equation (7) can be used on the right side of Equation (5). ｄ＿ｔｍｐ and the q-axis magnetic flux virtual value φ ｑ＿ｔｍｐ By rewriting equation (5) using the formula (7), the upper limits of the d-axis magnetic flux and the q-axis magnetic flux are obtained as the following formula (8). By using a field winding current that satisfies formula (8), the accuracy of the virtual d-axis magnetic flux value and the virtual q-axis magnetic flux value can be improved. Note that the permissible magnetic flux calculation unit 811 calculates the stator winding current command I ｄｒｅｆ , I ｑｒｅｆ and the field winding current I ｆ and the d-axis magnetic flux virtual value φ ｄ＿ｔｍｐ and the q-axis magnetic flux virtual value φ ｑ＿ｔｍｐ f shows the relationship ｄ and f ｑ can be stored as a map or function.

[0043]

[0044] To suppress voltage saturation by controlling the d-axis current, the d-axis magnetic flux can be weakened by limiting it to the side that weakens it. Since the q-axis magnetic flux changes little in the d-axis direction, the d-axis magnetic flux should satisfy the following equation (9).

[0045]

[0046] In other words, if the d-axis magnetic flux satisfies equation (9), voltage saturation can be suppressed. Therefore, the amount of magnetic flux that can be tolerated for voltage saturation is considered to be the allowable magnetic flux, and the d-axis component φ of the allowable magnetic flux is ｄｌｉｍ can be calculated using the following equation (10).

[0047]

[0048] Here, if the d-axis current is made too small in the negative direction, the d-axis magnetic flux becomes negative. Therefore, when it is desired to suppress voltage saturation, the d-axis current is set to the d-axis current lower limit value I ｄｍｉｎ It is necessary to set the d-axis current lower limit I within the range of the following equation (11). ｄｍｉｎ tends to increase monotonically with respect to the field winding current.

[0049]

[0050] d-axis current lower limit I ｄｍｉｎ is set to the d-axis current that makes the d-axis magnetic flux zero. ｄｍｉｎ is the upper limit value I of the current that can be passed through the stator winding power conversion unit and the rotating machine. ｄｑｍａｘ Here, the upper limit current I ｄｑｍａｘ is the upper limit of the square root of the sum of the squares of the d-axis current and the q-axis current, determined by the rotating machine 2 and the stator winding power conversion unit 4.

[0051] Therefore, taking into consideration equation (11), the second q-axis magnetic flux virtual value φ is calculated as shown in the following equation (12): ｑ＿ｔｍｐ２ If we use this, the d-axis component of the allowable magnetic flux φ ｄｌｉｍ The allowable magnetic flux calculation unit 811 calculates the d-axis current lower limit I ｄｍｉｎ , q-axis stator winding current command I ｑｒｅｆ and the field winding current I ｆ and the second q-axis magnetic flux virtual value φ ｑ＿ｔｍｐ２ f shows the relationship ｑ can be stored as a map or function.

[0052]

[0053] The output torque T of the rotating machine is expressed as the number of pole pairs P ｍThen, it is given by the following equation (14).

[0054]

[0055] Torque command T ｒｅｆ is given, the d-axis component of the allowable magnetic flux φ ｄｌｉｍ can be calculated by the following equation (15): By utilizing the given torque command, the calculation of the third term on the right side can be simplified, and the processing load can be reduced.

[0056]

[0057] d-axis component φ of allowable magnetic flux ｄｌｉｍ The second term on the right side is the d-axis current lower limit I ｄｍｉｎ By using the d-axis current lower limit instead of the d-axis component of the stator winding current command, the calculation formula can be made to better reflect the current state.

[0058]

[0059] So far, we have explained the case where the d-axis component of the allowable magnetic flux in the allowable magnetic flux calculation unit 811 is restricted in the weakening direction. Alternatively, the allowable magnetic flux calculation unit 811 may restrict the q-axis component of the allowable magnetic flux as the allowable magnetic flux in the weakening direction. For example, the allowable magnetic flux calculation unit 811 calculates the q-axis component φ of the allowable magnetic flux using the following equation (17) or (18), etc. ｑｌｉｍ The allowable magnetic flux calculation unit 811 may calculate the q-axis component φ of the allowable magnetic flux. ｑｌｉｍ Calculating the above formula is effective when voltage saturation cannot be suppressed even if the d-axis current is reduced to the d-axis current lower limit value, particularly in a region where the rotation speed of the rotating machine is high.

[0060]

[0061]

[0062] The field winding current, the stator winding current command, and the allowable magnetic flux are input to the first flux-weakening current calculation unit 812. The first flux-weakening current calculation unit 812 calculates the first flux-weakening current based on the field winding current, the stator winding current command, and the allowable magnetic flux using equations (19) to (22) described below.

[0063] The first flux-weakening current calculation unit 812 calculates the d-axis component φ of the allowable flux. ｄｌｉｍ is obtained, the d-axis component I of the first flux-weakening current is calculated by the following equation (19): ｄ＿ｆｗ The first flux-weakening current calculation unit 812 calculates the d-axis component I of the first flux-weakening current. ｄ＿ｆｗ d-axis current lower limit I ｄｍｉｎ Lower limit clipping may be performed.

[0064]

[0065] 8 is a diagram showing the relationship between the d-axis magnetic flux, which is the d-axis component of the allowable magnetic flux, and the q-axis current for a specific field winding current. FIG. 8 is a diagram showing the relationship of equation (19) for a specific field winding current. The first flux-weakening current calculation unit 812 calculates the field winding current, the d-axis magnetic flux, which is the d-axis component of the allowable magnetic flux, and the q-axis current, as shown in FIG. ｄ can be stored as a map or function.

[0066] The first flux-weakening current calculation unit 812 calculates the q-axis component φ of the allowable flux. ｑｌｉｍ is obtained, the q-axis component I of the first flux-weakening current is calculated by the following equation (20): ｑ＿ｆｗ The first flux-weakening current calculation unit 812 calculates the field winding current, the q-axis magnetic flux which is the q-axis component of the allowable magnetic flux, and g which shows the relationship between the q-axis current and the d-axis current. ｑ The first flux-weakening current calculation unit 812 may store the q-axis component I ｑ＿ｆｗ The upper limit of current I ｄｑｍａｘ Upper limit clipping may be performed by

[0067]

[0068] The first flux-weakening current calculation unit 812 calculates the d-axis component φ of the allowable flux. ｄｌｉｍ and the q-axis component φ ｑｌｉｍ When both of these are obtained, the d-axis component I of the first flux-weakening current is obtained by equation (19). ｄ＿ｆｗ is calculated, and the q-axis component I of the first flux-weakening current is calculated using the following equation (21): ｑ＿ｆｗThe first flux-weakening current calculation unit 812 calculates the field winding current, the d-axis component of the allowable flux, and g ｄ , the field winding current, the q-axis component of the allowable magnetic flux, and the relationship between the d-axis current and the q-axis current. ｑ The first flux-weakening current calculation unit 812 may store the upper limit value I ｄｑｍａｘ The d-axis component I of the first flux-weakening current is ｄ＿ｆｗ and the q-axis component I ｑ＿ｆｗ Upper limit clipping may be performed on

[0069]

[0070] The first flux-weakening current calculation unit 812 calculates the d-axis component φ of the allowable flux. ｄｌｉｍ is not obtained, the d-axis component of the first flux-weakening current is I ｄｒｅｆ The first flux-weakening current calculation unit 812 sets the q-axis component φ of the allowable flux. ｑｌｉｍ If the above equation is not obtained, the q-axis component of the first flux-weakening current is calculated by the following equation (22).

[0071]

[0072] The stator winding current command and the first flux-weakening current are input to the final current command calculation unit 813. The final current command calculation unit 813 calculates the final stator winding current command based on the stator winding current command and the first flux-weakening current using equations (23) to (25) described below.

[0073] d-axis component I of final stator winding current command ｄｔｇｔ If it is necessary to suppress voltage saturation, ｄ＿ｆｗ Therefore, the final current command calculation unit 813 calculates the d-axis component I of the final stator winding current command by the following equation (23): ｄｔｇｔ Calculate.

[0074]

[0075] q-axis component I of the final stator winding current command ｑｔｇｔ If it is necessary to suppress voltage saturation, ｑ＿ｆｗTherefore, the final current command calculation unit 813 calculates I ｑｒｅｆ When is positive, the q-axis component I of the final stator winding current command is calculated by the following equation (24): ｑｔｇｔ Furthermore, the final current command calculation unit 813 calculates I ｑｒｅｆ When is negative, the q-axis component I of the final stator winding current command is calculated by the following equation (25): ｑｔｇｔ Calculate.

[0076]

[0077]

[0078] In the control device for a rotating machine configured in this manner, the stator winding voltage command unit outputs the final stator winding current command I ｑｔｇｔ and I ｑｔｇｔ The stator winding voltage command is generated based on the integral control so that the stator winding current follows the final stator winding current command. This makes it possible to suppress windup of integral control and unintended magnetic flux interference between the stator winding and field winding in a rotating machine. As a result, the control device for a rotating machine of this embodiment can suppress saturation of the stator winding voltage command and perform stable current control. Note that windup of integral control means that there is a large deviation between the target value and the current value in integral control, and the deviation is added beyond the saturation limit, making it difficult to respond immediately when the deviation reverses.

[0079] Second Embodiment Fig. 9 is a configuration diagram showing the function of a current command generating unit in a rotating machine control device according to a second embodiment. The configuration of the rotating machine control device according to this embodiment is the same as the configuration shown in Fig. 1 of the first embodiment. The functional configuration of the processor in the rotating machine control device according to this embodiment is also the same as the configuration shown in Fig. 5 of the first embodiment. In the rotating machine control device according to this embodiment, the configuration of the current command generating unit within the processor is different from the configuration of the current command generating unit in the first embodiment.

[0080] As shown in FIG. 9 , the current command generation unit 81 of the present embodiment is obtained by adding a second flux-weakening current calculation unit 814 and a final flux-weakening current determination unit 815 to the current command generation unit shown in FIG. 6 of the first embodiment.

[0081] The second flux-weakening current calculation unit 814 receives a DC voltage and an applied voltage. The applied voltage is the voltage applied to the stator winding calculated from the stator winding voltage command output by the stator winding voltage command unit. The second flux-weakening current calculation unit 814 determines that voltage saturation occurs when the applied voltage is greater than the DC voltage, and calculates the second flux-weakening current by feeding back the deviation between the applied voltage and the DC voltage. For example, the second flux-weakening current calculation unit 814 includes a high-frequency amplifier, a subtractor, and a compensator. The high-frequency amplifier calculates a corrected applied voltage by amplifying the high-frequency component of the input applied voltage. The subtractor calculates the voltage deviation by subtracting the corrected applied voltage from a target applied voltage determined by the DC voltage and a target voltage utilization rate. The compensator calculates the second flux-weakening current based on the voltage deviation calculated by the subtractor.

[0082] The first flux-weakening current calculation unit 812 is suitable for cases where a high-speed flux-weakening current is required when the operation command changes suddenly. However, if the specifications of the rotating machine and the control device deviate from the pre-expected specifications, there is a possibility that the flux-weakening current will be excessive or insufficient. In a steady state where there are no sudden changes in rotation speed and the current flowing through the winding can roughly follow the current command, it is possible to select the optimal flux-weakening current by also using a method that feedbacks the steady state. The second flux-weakening current calculation unit 814 is provided to calculate the flux-weakening current in the steady state.

[0083] The final flux-weakening current determiner 815 receives as input the first flux-weakening current calculated by the first flux-weakening current calculator 812, the second flux-weakening current calculated by the second flux-weakening current calculator 814, and a field winding current command and field winding current (not shown). The final flux-weakening current determiner 815 determines the final flux-weakening current by selecting either the first flux-weakening current input from the first flux-weakening current calculator 812 or the second flux-weakening current input from the second flux-weakening current calculator 814, or by calculating a weighted average of both. The final flux-weakening current determiner 815 then outputs the determined final flux-weakening current to the final current command calculator 813.

[0084] The stator winding current command and field winding current command calculated by the current command calculation unit 810 are usually calculated taking into account voltage saturation. However, when the field winding current is significantly larger than the field winding current command, the d-axis magnetic flux φ in equation (1) ｄ becomes larger than expected, and voltage saturation makes it difficult for the stator winding current to follow the stator winding current command. In order to stabilize current control in such a case, it is necessary to ensure a final flux-weakening current early and suppress voltage saturation. In other words, when the field winding current is significantly larger than the field winding current command, it is necessary to select the first flux-weakening current calculated by the first flux-weakening current calculation unit 812. Specifically, this type of situation is likely to occur when the field winding current command is rapidly reduced in a converter such as that shown in FIG. 4.

[0085] On the other hand, in a steady state where there are no sudden changes in rotation speed and the current flowing through the windings can closely follow the current command, a rapid response is not required, and therefore selecting the second flux-weakening current calculated by the second flux-weakening current calculation unit can optimize the stator winding current and achieve efficient operation.

[0086] In the rotating machine control device of this embodiment, current command generation unit 81 includes second flux-weakening current calculation unit 814 and final flux-weakening current determination unit 815. Therefore, the rotating machine control device of this embodiment can select the first flux-weakening current calculated by the first flux-weakening current calculation unit when the field winding current is significantly larger than the field winding current command, and can select the second flux-weakening current calculated by the second flux-weakening current calculation unit in other cases. As a result, the rotating machine control device of this embodiment can perform optimal current control in a steady state, taking into account variations in the specifications of the rotating machine and the control device, and can quickly eliminate voltage saturation even when the rotational speed changes suddenly.

[0087] A final flux-weakening current determiner 815 calculates the deviation between the field winding current and the field winding current command, and sets a first threshold value and a second threshold value greater than the first threshold value for the deviation. When the deviation between the field winding current and the field winding current command is smaller than the first threshold value, the final flux-weakening current determiner 815 determines the second flux-weakening current calculated by the second flux-weakening current calculator 814 as the final flux-weakening current. When the deviation between the field winding current and the field winding current command is greater than the second threshold value, the final flux-weakening current determiner 815 determines the first flux-weakening current calculated by the first flux-weakening current calculator 812 as the final flux-weakening current. Furthermore, when the deviation between the field winding current and the field winding current command is equal to or greater than the first threshold value and equal to or less than the second threshold value, a final flux-weakening current determiner 815 determines the weighted average of the first flux-weakening current input from the first flux-weakening current calculator 812 and the second flux-weakening current input from the second flux-weakening current calculator 814 as the final flux-weakening current.

[0088] Although various exemplary embodiments and examples are described in this application, the various features, aspects, and functions described in one or more embodiments are not limited to the application of a particular embodiment, but may be applied to the embodiments alone or in various combinations. Therefore, countless variations not illustrated are contemplated within the scope of the technology disclosed in this specification. For example, this includes cases where at least one component is modified, added, or omitted, and even cases where at least one component is extracted and combined with components of other embodiments.

[0089] REFERENCE SIGNS LIST 1 control device, 2 rotating machine, 3 DC power supply, 4 stator winding power conversion unit, 5 field winding power conversion unit, 6 stator winding current detection unit, 7 field winding current detection unit, 8 processor, 9 storage device, 81 current command generation unit, 82 stator winding voltage command unit, 83 stator winding switching command generation unit, 84 field winding voltage command unit, 85 field winding switching command generation unit, 810 current command calculation unit, 811 allowable magnetic flux calculation unit, 812 first flux-weakening current calculation unit, 813 final current command calculation unit, 814 second flux-weakening current calculation unit, 815 final flux-weakening current determination unit.

Claims

1. A control device for a rotating machine having a rotor with a field winding and a stator with a stator winding, a current command generating unit that generates a field winding current command for a field winding current and a stator winding current command for a stator winding current based on an operation command input from outside; a field winding voltage command unit that generates a field winding voltage command for a voltage applied to the field winding based on the field winding current command; a stator winding voltage command unit that generates a stator winding voltage command for a voltage to be applied to the stator winding based on the stator winding current command; a field winding power conversion unit that applies a voltage to the field winding based on the field winding voltage command; a stator winding power conversion unit that applies a voltage to the stator winding based on the stator winding voltage command, a first flux-weakening current calculation unit that calculates a first flux-weakening current based on the field winding current, the stator winding current command, and the allowable flux; and a final current command calculation unit that calculates a final stator winding current command based on the stator winding current command and the first flux-weakening current.

2. 2. The control device for a rotating machine according to claim 1, wherein the allowable magnetic flux calculation unit calculates the allowable magnetic flux based on a d-axis current lower limit determined by the field winding current.

3. 2. The control device for a rotating machine according to claim 1, wherein the allowable magnetic flux calculation unit calculates the allowable magnetic flux based on a torque command included in the operation command.

4. 4. The control device for a rotating machine according to claim 2, wherein the allowable magnetic flux calculated by the allowable magnetic flux calculation unit is a d-axis component.

5. 4. The control device for a rotating machine according to claim 1, wherein the first flux-weakening current calculation unit calculates a d-axis component of the first flux-weakening current based on the field winding current, a q-axis component of the stator winding current command, and a d-axis component of the allowable magnetic flux.

6. 4. The control device for a rotating machine according to claim 1, wherein the first flux-weakening current calculation unit calculates the q-axis component of the first flux-weakening current based on the field winding current, a d-axis current lower limit, and a q-axis component of the allowable magnetic flux.

7. 4. The rotating machine control device according to claim 1, wherein the first flux-weakening current calculation unit calculates a d-axis component of the first flux-weakening current based on the field winding current, a q-axis component of the stator winding current command, and a d-axis component of the allowable flux, and calculates a q-axis component of the first flux-weakening current based on the field winding current, the first flux-weakening current, and the q-axis component of the allowable flux.

8. a second flux-weakening current calculation unit that calculates a second flux-weakening current based on the voltage applied to the stator winding; a final flux-weakening current determination unit that determines either the first flux-weakening current or the second flux-weakening current as a final flux-weakening current based on a deviation between the field winding current and the field winding current command, or that determines a weighted average of the first flux-weakening current and the second flux-weakening current as a final flux-weakening current based on a deviation between the field winding current and the field winding current command, 4. The control device for a rotating machine according to claim 1, wherein the final current command calculation unit calculates the final stator winding current command based on the final flux-weakening current determined by the final flux-weakening current determination unit and the stator winding current command.

9. 9. The rotary machine control device according to claim 8, wherein the final flux-weakening current determiner calculates a deviation between the field winding current and the field winding current command, sets a first threshold value and a second threshold value greater than the first threshold value for the deviation, and determines the second flux-weakening current as the final flux-weakening current when the deviation is smaller than the first threshold value, determines the first flux-weakening current as the final flux-weakening current when the deviation is greater than the second threshold value, and determines a weighted average of the first flux-weakening current and the second flux-weakening current as the final flux-weakening current when the deviation is equal to or greater than the first threshold value and equal to or less than the second threshold value.