Drive device

Abstract

To suppress disturbance of field magnetic flux and torque control of a motor when a field current is not detected in a configuration including a winding field type motor.SOLUTION: Setting d-axis and q-axis voltage commands on the basis of a torque command and d-axis and q-axis currents of a motor, setting a field current command on the basis of the torque command, calculating d-axis and q-axis magnetic fluxes on the basis of the d-axis and q-axis currents and the field current command, calculating a d-axis magnetic flux error on the basis of the d-axis and q-axis currents, the d-axis and q-axis voltage commands, and the d-axis and q-axis magnetic fluxes, and calculating a field voltage command such that the d-axis magnetic flux error has a value of 0; The first power converter is controlled based on the d-axis and q-axis voltage commands, and the second power converter is controlled based on the field voltage command.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a drive device. [Background technology]

[0002] A conventional control device for an induction motor driven by three-phase AC current converted from DC current from a DC power supply has been proposed, which converts two-phase commands, namely a torque command and a magnetic flux density command, into a three-phase primary voltage command for controlling the primary current of the induction motor, converts the three-phase primary current detection values ​​of the induction motor into two-phase detection values, namely a torque current detection value and an excitation current detection value, and performs feedback control (see, for example, Patent Document 1). This control device performs the following processes: Calculates an excitation current command based on the magnetic flux density command, the estimated magnetic flux density value, the detected DC voltage value of the DC power supply, the leakage inductance, and the angular frequency command; Calculates an estimated magnetic flux density value based on the excitation current command; Calculates an excitation current error based on the excitation current command and the excitation current detection value, and calculates an excitation current in-phase voltage command that is in phase with the excitation current based on the calculated excitation current error; and Calculates a torque current command based on the torque command, the estimated magnetic flux density value, and the excitation current command. A torque current error is calculated based on the torque current command and the torque current detection value, a torque current in-phase voltage command that is in phase with the torque current is calculated based on the calculated torque current error, and a three-phase primary voltage command to be applied to the induction motor is calculated based on the excitation current in-phase voltage command and the torque current in-phase voltage command. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-8500 Summary of the Invention [Problem to be solved by the invention]

[0004] Unlike induction motors, wound-field motors generate field flux due to the field current in the rotor's field winding. In the case of brushed wound-field motors, a current sensor can be installed to detect the field current and calculate the field flux based on this. However, in brushless motors, it is difficult to detect the field current and calculate the field flux based on the field current. This can lead to disruptions in the field flux and, ultimately, motor torque control. Even in brushed motors, similar issues arise when there is a need to omit the current sensor.

[0005] The driving device of the present disclosure has a configuration including a wound field motor, and its main purpose is to suppress disturbances in field flux and therefore motor torque control when field current detection is not performed. [Means for solving the problem]

[0006] The driving device of the present disclosure employs the following means to achieve the above-mentioned main object. A drive device disclosed herein includes a wound-field motor including a stator having a stator winding and a rotor having a field winding, a first power conversion unit that supplies three-phase AC power to the stator winding, a second power conversion unit that applies a field voltage to the field winding, and a control device that controls the first and second power conversion units, wherein the control device sets d-axis and q-axis voltage commands based on a torque command and d-axis and q-axis currents of the motor, sets a field current command based on the torque command, calculates d-axis and q-axis magnetic flux based on the d-axis and q-axis currents and the field current command, calculates a d-axis magnetic flux error based on the d-axis and q-axis currents, the d-axis and q-axis voltage commands, and the d-axis and q-axis magnetic flux, calculates a field voltage command so that the d-axis magnetic flux error becomes zero, and controls the first power conversion unit based on the d-axis and q-axis voltage commands and controls the second power conversion unit based on the field voltage command.

[0007] The drive device disclosed herein sets d-axis and q-axis voltage commands based on a motor torque command and d-axis and q-axis currents, sets a field current command based on the torque command, calculates d-axis and q-axis magnetic flux based on the d-axis and q-axis currents and the field current command, calculates a d-axis magnetic flux error based on the d-axis and q-axis currents, the d-axis and q-axis voltage commands, and the d-axis and q-axis magnetic flux, calculates a field voltage command so that the d-axis magnetic flux error becomes zero, controls a first power conversion unit based on the d-axis and q-axis voltage commands, and controls a second power conversion unit based on the field voltage command. This prevents the d-axis magnetic flux error from increasing. As a result, disturbances in field flux and therefore motor torque control can be prevented when field current detection is not performed. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a configuration of a drive device 20 according to an embodiment of the present disclosure. [Figure 2] 2 is a schematic diagram of a rotor of a motor 22 and a circuit of a second power conversion unit 26 included in a drive device 20. FIG. [Figure 3] 3 is a block diagram showing an example of functional blocks in the control of a first power conversion unit 24 and a second power conversion unit 26 by an ECU 50. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic diagram of a configuration of a drive device 20 according to an embodiment of the present disclosure. Fig. 2 is a schematic diagram of a rotor of a motor 22 and a circuit of a second power conversion unit 26 provided in the drive device 20. As shown in Fig. 1, the drive device 20 according to the embodiment is mounted on an electric vehicle 10 and includes the motor 22, a first power conversion unit 24, a second power conversion unit 26, a battery 30, and an electronic control unit (hereinafter referred to as "ECU") 50.

[0010] The motor 22 is configured as a wound-field, brushless motor and includes a stator with three-phase (U-phase, V-phase, and W-phase) stator windings wound around a stator core, and a rotor with a field winding wound around a rotor core. In addition to the rotor core and field winding, the rotor also includes a secondary coil 22t that, together with a primary coil 26t of the second power conversion unit 26, forms a transformer, and an AC / DC conversion unit 22ad that converts AC power from the secondary coil 22t into DC power and supplies it to the field winding (winding inductance Lo and winding resistance Ro in FIG. 2). The AC / DC conversion unit 22ad includes four diodes D1 to D4. The diodes D1 to D4 are arranged in pairs, two on each side, on the source side and sink side of a positive line and a negative line connected to one end and the other end of the field winding. The connection points of the pair of diodes D1 to D4 are connected to one side and the other side of the secondary coil 22t, respectively. A rotor shaft, to which the rotor (rotor core) is connected, is connected to a drive shaft 16, which is coupled to drive wheels 12a and 12b via a differential gear 14.

[0011] The first power conversion unit 24 is connected to a power line 32 to which the battery 30 is connected, and is also connected to a three-phase stator winding. The first power conversion unit 24 is configured as a three-phase inverter circuit including a plurality of switching elements.

[0012] The second power conversion unit 26 is connected to the power line 32. The second power conversion unit 26 includes a primary coil 26t that, together with the secondary coil 22t of the rotor of the motor 22, forms a transformer, and a DC / AC conversion unit 26da that converts DC power from the power line 32 into AC power and supplies it to the series inductor Lr and the primary coil 26t, which are connected in series with each other. The DC / AC conversion unit 26da includes transistors Q1 to Q4 as four switching elements. The four transistors Q1 to Q4 are arranged in pairs, two on the source side and two on the sink side with respect to the positive and negative lines of the power line 32. The connection points of the paired transistors Q1 to Q4 are connected to one side and the other side of the primary coil 26t.

[0013] The battery 30 is configured as, for example, a lithium ion secondary battery or a nickel-metal hydride secondary battery, and is connected to a power line 32. A smoothing capacitor 34 is connected to the power line 32.

[0014] The ECU 50 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and logic ICs. The ECU 50 receives signals from various sensors. For example, the ECU 50 receives the rotational position θm of the rotor of the motor 22 from a rotational position sensor 22a, and the phase currents Iu, Iv, and Iw of each phase (U-phase, V-phase, and W-phase) of the motor 22 from current sensors 22u, 22v, and 22w. The ECU 50 also receives the voltage Vb and current Ib of the battery 30 from a voltage sensor and a current sensor, and the voltage VH of the capacitor 34 (power line 32) from a voltage sensor 34a. The ECU 50 also receives inputs of an on / off signal from a power switch 60, the operating position of a shift lever 61 (shift position SP) from a shift position sensor 62, the depression amount of an accelerator pedal 63 (accelerator opening Acc) from an accelerator pedal position sensor 64, the depression amount of a brake pedal 65 (brake pedal position BP) from a brake pedal position sensor 66, and a vehicle speed V from a vehicle speed sensor 67. The ECU 50 outputs control signals to the first power conversion unit 24 and the second power conversion unit 26. The ECU 50 calculates the electrical angle θe and rotation speed Nm of the motor 22 based on the rotational position θm of the rotor (rotor shaft) of the motor 22.

[0015] In the drive unit 20 mounted on the electric vehicle 10 of the embodiment, the ECU 50 sets the required torque Td* required for driving (required of the drive shaft 16) based on the accelerator opening Acc and the vehicle speed V, sets the torque command Tm* of the motor 22 so that the set required torque Td* is output to the drive shaft 16, and controls the first power conversion unit 24 and the second power conversion unit 26 so that the motor 22 is driven based on the torque command Tm*.

[0016] 3 is a block diagram showing an example of functional blocks in the control of the first power conversion unit 24 and the second power conversion unit 26 by the ECU 50. The ECU 50 includes, as functional blocks, a normal dq-axis control unit 71, a field current command setting unit 72, a d-axis and q-axis magnetic flux calculation unit 73, a d-axis magnetic flux error estimator 74, a subtractor 75, and a field current control unit 76.

[0017] Typically, the dq-axis control unit 71 executes the following process. First, the phase currents Iu, Iv, and Iw of each phase are converted to d-axis and q-axis currents Id and Iq (three-phase to two-phase conversion) using the electrical angle θe of the motor 22, and the d-axis and q-axis current commands Id* and Iq* are set based on the torque command Tm*. The d-axis and q-axis current commands Id* and Iq* are set, for example, by applying the torque command Tm* to a map that has been determined in advance through experiments, analysis, or the like as the relationship between the torque command Tm* and the current commands Id* and Iq*, and deriving the corresponding current commands Id* and Iq* from the map. Next, the d-axis and q-axis voltage commands Vd* and Vq* are calculated by feedback control so that the differences (Id*-Id), (Iq*-Iq) between the d-axis and q-axis current commands Id* and Iq* and the currents Id and Iq are canceled out. Then, using the electrical angle θe, the d-axis and q-axis voltage commands Vd*, Vq* are coordinate-converted (two-phase to three-phase conversion) into phase voltage commands Vu*, Vv*, Vw* for each phase, and the obtained phase voltage commands Vu*, Vv*, Vw* for each phase are used to control the first power conversion unit 24. Specifically, the multiple switching elements of the first power conversion unit 24 are controlled so that the phase voltages of the phase voltage commands Vu*, Vv*, Vw* for each phase are applied to the respective phases.

[0018] The field current command setting unit 72 sets the field current command If* based on the torque command Tm* and rotation speed Nm of the motor 22 and the voltage VH of the capacitor 34 (power line 32). The field current command If* is set, for example, by applying the torque command Tm*, rotation speed Nm, and voltage VH to a map that has been determined in advance by experimentation, analysis, or the like as the relationship between the torque command Tm*, rotation speed Nm, voltage VH, and field current command If*, and deriving the corresponding field current command If* from the map.

[0019] The d-axis and q-axis magnetic flux calculation unit 73 calculates the d-axis and q-axis magnetic fluxes φd and φq based on the d-axis and q-axis currents Id and Iq from the normal dq-axis control unit 71 and the field current command If* from the field current command setting unit 72. The magnetic fluxes φd and φq are obtained, for example, by applying the currents Id and Iq and the field current command If* to a map previously determined through experiments, analysis, or the like as the relationship between the currents Id and Iq, the field current command If*, and the magnetic fluxes φd and φq, and deriving the corresponding magnetic fluxes φd and φq from the map. The magnetic fluxes φd and φq may also be calculated using equations (1) and (2). "Ld" and "Lq" are the d-axis and q-axis inductances, respectively, and "M1" is the mutual inductance from the rotor side to the stator side, which are previously determined through experiments, analysis, or the like.

[0020] φd=Ld·Id+M1·If* (1) φq=Lq·Iq (2)

[0021] The d-axis magnetic flux error estimator 74 estimates the d-axis magnetic flux error Δφd using a state observer that uses, for example, equations (5) and (6) in which each variable in the drive device 20 is substituted into equations (3) and (4). In equations (5) and (6), "φdes" and "φqes" are the estimated magnetic fluxes (estimated magnetic flux values) of the d-axis and q-axis, respectively, "ωm" is the angular velocity in electrical angle of the motor 22, "Rm" is the stator resistance, and "Yes" is a temporary variable. In this embodiment, the d-axis magnetic flux error Δφd is estimated so that the d-axis and q-axis magnetic fluxes φd and φq from the d-axis and q-axis magnetic flux calculator 73 match the temporary variable Yes in equation (6), i.e., the estimated d-axis and q-axis magnetic fluxes φdes and φqes.

[0022]

number

[0023]

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[0024] Equations (5) and (6) are derived as follows. First, the general relationship between the d-axis and q-axis voltages Vd, Vq, stator resistance Rm, the d-axis and q-axis currents Id, Iq, the d-axis and q-axis magnetic fluxes φd, φq, and the angular velocity ωm of the motor 22 can be expressed by equations (7) and (8). In equations (7) and (8), assuming that there is an error in the field current If, which results in a d-axis magnetic flux error Δφd (φd → φd + Δφd), and substituting the d-axis and q-axis voltages Vd, Vq and magnetic fluxes φd, φq with voltage commands Vd*, Vq* and estimated magnetic fluxes φdes, φqes, equations (5) and (6) can be derived.

[0025] Vd=Rm·Id+dφd / dt-ωm·φq (7) Vq=Rm·Iq+dφq / dt+ωm·φd (8)

[0026] The subtractor 75 calculates the difference (-Δφd) between the value 0 and the d-axis magnetic flux error Δφ. The field current controller 76 calculates a field voltage command Vf* by feedback control so as to cancel the difference (-Δφd) and controls the second power converter 26 using the calculated field voltage command Vf*. Specifically, the DC / AC converter 26da is controlled so that the voltage of the field voltage command Vf* is applied to the field winding of the rotor. In this embodiment, the phase width during which the transistors Q1 and Q4 are turned on and the phase width during which the transistors Q2 and Q3 are turned on are controlled by controlling the amount of shift of the on / off phase of the transistor Q3 (the off / on phase of the transistor Q4) relative to the on / off phase of the transistor Q1 (the off / on phase of the transistor Q2) based on the field voltage command Vf*. In this way, the d-axis magnetic flux error Δφd can be prevented from increasing. As a result, when the field current If is not detected, the field flux φf and, therefore, the torque control of the motor 22 can be prevented from being disturbed.

[0027] The drive unit 20 mounted on the electric vehicle 10 according to the embodiment described above sets d-axis and q-axis voltage commands Vd*, Vq* based on the torque command Tm* and currents Id, Iq of the motor 22, sets a field current command If* based on the torque command Tm*, determines d-axis and q-axis magnetic fluxes φd, φq based on the currents Id, Iq and the field current command If*, calculates a d-axis magnetic flux error Δφd based on the currents Id, Iq, voltage commands Vd*, Vq*, and magnetic fluxes φd, φq, calculates a field voltage command Vf* so that the magnetic flux error Δφd becomes zero, and controls the first power converter 24 based on the voltage commands Vd*, Vq* and the second power converter 26 based on the field voltage command Vf*. This prevents the d-axis magnetic flux error Δφd from increasing. As a result, disturbances in the field flux φf and, ultimately, the torque control of the motor 22 can be prevented when the field current If is not detected.

[0028] In the above-described embodiment, the motor 22 is configured as a wound field type brushless motor, but it may also be configured as a wound field type brushed motor.

[0029] In the above-described embodiment, the drive unit 20 is mounted on an electric vehicle 10 equipped with a motor 22, but is not limited to this. For example, the drive unit may be mounted on a hybrid vehicle that further includes an engine in addition to a motor, or on a fuel cell vehicle that further includes a fuel cell in addition to a motor.

[0030] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0031] The present disclosure is applicable to industries such as the drive device manufacturing industry. [Explanation of symbols]

[0032] 20 drive device, 22 motor, 24 first power conversion unit, 26 second power conversion unit, 50 ECU (control device).

Claims

[Claim 1] A drive device comprising: a wound field motor including a stator having a stator winding and a rotor having a field winding; a first power conversion unit that supplies three-phase AC power to the stator winding; a second power conversion unit that applies a field voltage to the field winding; and a control device that controls the first and second power conversion units, the control device sets d-axis and q-axis voltage commands based on a torque command of the motor and d-axis and q-axis currents, sets a field current command based on the torque command, calculates d-axis and q-axis magnetic fluxes based on the d-axis and q-axis currents and the field current command, calculates a d-axis magnetic flux error based on the d-axis and q-axis currents, the d-axis and q-axis voltage commands, and the d-axis and q-axis magnetic fluxes, calculates a field voltage command so that the d-axis magnetic flux error becomes zero, controls the first power conversion unit based on the d-axis and q-axis voltage commands, and controls the second power conversion unit based on the field voltage command. Drive unit.

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