JP2006203957A - Turbocharger assisting motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform backup operation while maintaining the formation of a rotating magnetic field of a motor when an abnormality such as a disconnection short circuit occurs at one of phases, in the motor that assists the rotation of a turbocharger. <P>SOLUTION: A six-phase stator winding is divided into two Y-connection lines 11, 12 that are shifted from each other at 60°-phases by three phases, and the lines are connected. The two Y-connection lines 11, 12 are cooperated to six-phase drive the motor at a normal time, and when the short-circuit disconnection is detected at one phase 11a among the phases, the drive of the motor by the Y-connection line 11 including the phase 11a is interrupted, and the motor is three-phase driven by only the Y-connection line 12 composed of the normal phases. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a turbocharger assist motor that assists in rotational driving of a turbocharger.

  In order to improve the start-up response of the rotation of the turbocharger, it is conceivable to assist the rotating shaft of the turbocharger with an electric motor. However, the turbocharger rotates at a very high speed from 10,000 to 20,000 revolutions at idling to about 200,000 revolutions at full load. Such ultra-high speed rotational driving places a heavy burden on the motor and its driving device. Japanese Patent Application Laid-Open No. 6-121585 discloses that a motor is driven at an ultra-high speed by charging a capacitor with magnetic energy accumulated in a three-phase Y-type stator winding, and then rising of the next stator winding current. Proposals have been proposed in which

JP-A-6-121585

  A turbocharger cannot completely eliminate the possibility that a motor or a drive device will fail during its entire use year due to the excessive burden caused by its ultra-high speed rotation. In a motor-assisted turbocharger, if the rotating magnetic field cannot be configured when the motor or drive circuit is abnormal and the driving force of the motor stops instantaneously, the fuel in the cylinder of the engine becomes excessive due to a sudden drop in the intake air volume, resulting in a misfire. Or the exhaust will get worse. Furthermore, a sudden decrease in engine output during driving may cause a sudden change in the driving state of the vehicle and impair the safety of the vehicle. Therefore, there is a need for a backup function that does not suddenly change the turbocharger or compressor speed in the event of any abnormality. Conventionally, an electric motor with such a backup function has not been proposed.

  Therefore, in the present invention, an electric motor that drives a rotating shaft of a turbocharger or a rotating shaft of a compressor has 6 phases of stator windings, and each of the 6-phase stator windings has a phase of 60 degrees with respect to each other. It is divided and combined into two shifted Y connections, phase abnormality detection means for detecting abnormality such as disconnection or short circuit of each phase of the stator winding, and 2 when no phase abnormality is detected. There is switching means for driving one Y connection in six phases and, when any phase abnormality is detected, cutting off the energization drive to the Y connection including that phase and driving the Y connection consisting only of normal phases in three phases A turbocharger-assist electric motor comprising: a drive device; The electric motor may be an induction motor or a brushless motor in which a permanent magnet is arranged on a rotor.

  If comprised as mentioned above, it will be rotationally driven smoothly as a 6-phase motor in normal times. When an abnormality is detected in any one of the phases, the Y connection including that phase is effectively disconnected from the driving device, and only the other Y connection is driven for three phases to form a rotating magnetic field having the same rotational speed. . At this time, it is the same as a normal three-phase motor, and although the responsiveness is lowered, the rotational speed to be driven is the same and torque rigging does not occur. Therefore, even if an abnormality occurs in any phase of the electric motor, the rotational speed of the turbocharger hardly decreases, and there is an effect that a backup function as a turbocharger assist motor can be achieved.

  FIG. 1 is a cross-sectional view showing a turbocharger 1 with an assist motor. A turbine 4 that is driven to rotate by the exhaust gas flow of the engine is fixed to the left end of the rotating shaft 6 that is rotatably supported in the housing 9. A compressor 5 that pressurizes intake air is fixed to the right end of the rotating shaft 6. These 9, 6, 4 and 5 constitute a turbocharger 7. Here, the electric motor 2 that assists the rising of the rotation of the turbo is incorporated. An induction motor is selected as the assist motor 2. That is, a cage rotor 8 made of aluminum die casting is attached to the rotating shaft 6. Six (six-phase) stator windings 10 are arranged and fixed every 60 ° in the surrounding housing 9 to constitute a stator.

  FIG. 2 is a block diagram showing the stator winding 10 and the driving device 20 of the assist motor 2. In the six-phase stator winding 10, three windings separated from each other by 120 ° are Y-connected, and two Y-connections 11 and 12 having a phase difference of 60 ° are formed. The first Y connection 11 includes three windings 11a, 11b, and 11c, and the second Y connection 12 includes three windings 12a, 12b, and 12c. The first Y connection 11 is connected to the first inverter 21, and the second Y connection 12 is connected to the second inverter 22. Electric power is supplied to each inverter 21, 22 from a power supply battery 30. The inverters 21 and 22 are three-phase inverters. For example, the first inverter 21 includes six switching elements 21a, 21b, 21c, 21d, 21e, and 21f as main elements. The same applies to the second inverter 22. The two inverters 21 and 22 are operated in cooperation to drive the assist motor 2 in six phases.

  For example, when any of the windings 11a, 11b, and 11c belonging to the first Y connection 11 is disconnected or short-circuited, the first inverter 21 is all stopped and the assist motor 2 is rotated only by the second inverter 22. To drive. That is, the assist electric motor 2 is driven to be backed up by a rotating magnetic field by exciting only the second Y connection 12 with three phases.

  FIG. 3 is a block diagram showing a control device for realizing the above control concept. The windings 11 a, 11 b, 11 c of the first Y connection 11 of the assist motor 2 are connected to the first inverter 21, and the windings 12 a, 12 b, 12 c of the second Y connection 12 are connected to the second inverter 22. Has been. Current sensors 51 and 52 are attached to the lines leading to the windings 11a and 11b of the first Y connection 11, respectively, and detect the phase currents i1 and i2. Since the phase current i3 is a Y connection, it can be calculated by i3 = − (i1 + i2). Similarly, current sensors 54 and 55 are attached to the lines leading to the windings 12a and 12b of the second Y connection 12, respectively, and detect the phase currents i4 and i5. Data of the phase currents i1, i2, i4, i5 is sent to the control device 40. The control device 40 outputs on / off signals of the six switching elements of the first inverter 21 and on / off signals of the six switching elements of the second inverter 22 based on data such as the motor speed and the motor rotation command value. The two series of on / off signals are sent to the gate drive circuits 23 and 24 of the inverters 21 and 22 via AND gates constituting the prohibiting means 44 and 45, respectively. When normal, 1 is input to the other input terminals of the AND gates 44 and 45.

  In the abnormality detection means 43 to which the phase current value of the motor is input, the average phase current value of the six phases is compared with the respective phase currents of the Y connections 11 and 12, and the abnormally large or abnormally small phase current is detected. A short circuit or disconnection of the phase is detected. When an abnormality is detected, a signal indicating whether the phase in which the abnormality has occurred is the first Y connection 11 or the second Y connection 12 is sent to the switching means 42. Based on the signal from the abnormality detection means 43, the switching means 42 outputs a prohibition signal to the prohibition means on the side that drives the Y connection where the abnormality is detected. For example, if an abnormality is detected in the first Y connection 11, “0” is output from the switching unit 42 to the first prohibiting unit 44, and the function of the prohibiting unit is AND. Always outputs "0". For this reason, the first inverter 21 stops. On the other hand, since “1” remains output from the switching means 42 to the second prohibition means 45, the six signals from the drive control means 41 are sent to the second gate drive circuit 24 as they are, and the second inverter. 22 continues driving.

  The drive control means 41 responds to the abnormal signal from the switching means 42, recognizes that the operation is in an abnormal state, and sends an operation command suitable for the backup operation to the gate drive circuit 24. As a result, the inverter 21 on the side where the abnormality is detected in the Y connection element is stopped, and the backup operation is continued only by the inverter 22 that drives the Y connection 12 on the normal side.

In the above description, the control device 40 has been described as if it were a circuit, but in reality, each means of the control device 40 is realized as processing by a macro processor. FIG. 4 is a flowchart showing processing by the macro processor. Processing is started in S1. In S2, the phase current is detected. The phase currents i1 and i2 are directly detected by the current sensors 51 and 52, and the phase current i3 is calculated by calculation as i3 = − (i1 + i2). Similarly, the phase currents i4 and i5 are directly detected by the current sensors 54 and 55, and the phase current i6 is calculated by calculation as i6 = − (i4 + i5).
In S3, the effective current (rms) of each phase and the average value Im of the six phases are obtained. In S4, a deviation value δIn (n = 1 to 6) from the average value Im of the effective current Inrms of each phase is calculated. Calculated as δIn = Im-Inrms. The deviation value δIn is a numerical value that can be either positive or negative, and is a negative value when the effective phase current is excessive.

In S5, it is determined whether or not each phase is disconnected. When the deviation value δIn is a positive value and larger than the predetermined value Imin, it is determined that δIn> Imin, the effective phase current is too small, and the winding of the phase is disconnected, and the process proceeds to S8. When the deviation value δIn is smaller than the predetermined value Imin in all six phases, it is determined that there is no disconnection of the winding, and the process proceeds to S6.
In S6, it is determined whether each phase is short-circuited. When the deviation value δIn is a negative value and smaller than the predetermined value Imax, it is determined that δIn <Imax, the effective phase current is excessive, and the winding of the phase is short-circuited, and the process proceeds to S8. When the deviation value δIn is larger than the negative predetermined value Imax in all six phases, it is determined that there is no short circuit of the winding and the process proceeds to S7. Then, the routine returns to S1, and the routine for checking the presence / absence of disconnection and short circuit of the windings of each phase is repeated again.

  If it is determined in S5 or S6 that the wire is broken or shorted, the process proceeds to S8. In S8, an abnormality determination flag is set to notify the drive control means 41 that an abnormality has occurred in the winding. Next, in S9, "0" is output to the prohibition means (AND gate) that sends a signal to the inverter that drives the Y connection where the abnormality is detected, and the corresponding inverter is stopped. Then, the process proceeds to S10 and the process ends.

  FIG. 5 is a waveform diagram showing an example of a voltage waveform applied to each phase of the stator winding of the assist motor 2. U, V, and W indicate phases of the first Y connection 11, and X, Y, and Z indicate phases of the second Y connection 12. During normal operation, as shown in the figure, the first Y connection 11 and the second Y connection 12 are excited by six phases with a 60 ° electrical angle shift. If an abnormality such as a short circuit breakage occurs in any phase, for example, one phase of the first Y-connection 11, the prohibiting means 44 stops the excitation of the U, V, and W phases and the applied voltage becomes zero. Then, only the second Y connection 12 of X, Y, and Z is applied with a voltage with a 120 ° electrical angle shift, the backup operation is started by three-phase excitation, and the turbocharger assist is continued.

  FIG. 6 is a block diagram illustrating a configuration example of a turbocharger with an assist motor. The exhaust manifold of the engine communicates with the turbocharger 61, and the exhaust turbine of the turbocharger 61 is rotationally driven to reach the exhaust path 66. The turbocharger 61 incorporates an electric motor (for example, induction machine) 62 and assists the rotation of the compressor turbine. The intake passage 65 communicates with the turbocharger 61 and the intake air is compressed by the compressor turbine. The compressed intake air is cooled by the intercooler 64 and guided to the intake manifold. Here, since the rotation of the turbocharger 61 includes not only the driving force of the compressor turbine due to the exhaust but also the driving force of the assist motor 62, the turbocharger 61 is particularly excellent in starting up the rotation.

  In the above-described embodiment, the rotating shaft of the turbocharger is auxiliary driven directly by the assist motor. However, it is of course possible to apply the present invention to an electric motor that rotationally drives the auxiliary compressor of the turbocharger.

  FIG. 7 is a block diagram illustrating a configuration example of a turbocharger with an assist motor compressor. The exhaust manifold of the engine 74 communicates with the turbocharger 73, and the exhaust turbine of the turbocharger 73 is rotationally driven to reach the exhaust path 78. The intake passage 77 communicates with the turbocharger 73, and the intake air is compressed by the compressor turbine of the turbocharger 73. The compressed intake air is sent to the auxiliary compressor 71 and further compressed. The auxiliary compressor 71 is driven to rotate by an assist motor 72. The pipe branched from the output pipe of the auxiliary compressor 71 and the output pipe of the turbocharger 73 is guided to the switching valve 76. The switching valve 76 is controlled by an electronic control unit (not shown), and the output of the auxiliary compressor 71 or the output of the turbocharger 73 is selected and the intake air is sent to the intercooler 75. The output of the intercooler 75 communicates with the intake manifold of the engine 74.

  FIG. 8 is a cross-sectional view of the auxiliary compressor 71. A rotating shaft 84 is rotatably supported by bearings 82 and 83 fixed to the casing 81. A compressor turbine 85 is fixed to the right end of the rotating shaft 84 and rotates at a high speed to compress the intake air in the intake passages 86 and 87. A rotor 89 made of a cage-type aluminum die cast is fixed to the left of the rotation shaft 84. Six-pole stator windings 88 and 88 are fixed to a casing 81 around the rotor 89, and the stator winding 88 and the rotor 89 constitute an assist motor 90 including an induction motor. The stator winding 88 composed of six phases is Y-connected in three phases, and two sets of Y-connected with a phase difference of 60 ° are formed. Similarly to the description with reference to FIGS. 2 to 5, when normal, the motor is rotated in six phases, and when one Y-connection fails, a rotating magnetic field of the same speed is applied to the other Y-connection. Maintain and enable backup operation. The auxiliary compressor 71 operates when the turbocharger 73 starts up and assists supercharging by the turbocharger 73. Thus, the assist electric motor according to the present invention can be applied not only to a turbocharger but also to a compressor.

  FIG. 9 is a block diagram showing a configuration of a conventional drive device. The number of output terminals of the three stator windings 100a, 100b, 100c of the induction motor 100 is six, and the drive circuit 200 is provided with inverters 201, 202, 203 for driving the respective windings. Since each inverter requires four switching elements 201a, 201b, 201c, and 201d, the total number of switching elements in the drive circuit 200 is 4 × 3 = 12. On the other hand, as shown in FIG. 2, the total number of switching elements of the drive circuit 20 of the present invention is 6 × 2 = 12, which is the same as the conventional drive circuit 200, and there is no cost increase of the drive circuit according to the present invention. .

In the embodiment described above, the electric motor has been described as an induction motor. However, it is obvious that the same backup control is possible even with a brushless motor in which a permanent magnet is arranged on the rotor of the electric motor.
Further, FIG. 5 shows a case where each phase is excited by a rectangular wave, but it is obvious that excitation may be performed by PWM.
Furthermore, although the short circuit breakage of each phase of the stator winding is detected by the current of each phase in the above embodiment, it can be detected from the voltage and impedance of each phase.

It is sectional drawing which shows the turbocharger with an assist electric motor. It is a block diagram which shows the stator winding | coil of an assist electric motor, and a drive device. It is a block diagram which shows the control apparatus which implement | achieves the control thought of this invention. It is a flowchart which shows the process by a macro processor. It is a wave form diagram which shows an example of the voltage waveform applied to each phase of the stator winding | coil of an assist electric motor. It is a block diagram which shows the structural example of the turbocharger with an assist electric motor. It is a block diagram which shows the structural example of the turbocharger with the assist electric motor compressor. It is sectional drawing of an auxiliary compressor. It is a block diagram which shows the structure of the conventional drive device.

Explanation of symbols

2 Assist induction motor 7 Turbocharger 10 Stator winding 11 First Y connection 12 Second Y connection 20 Drive device 21 First three-phase inverter 22 Second three-phase inverter 30 Power supply battery 40 Control device 42 Switching means 43 Abnormality detection means 44, 45 Prohibition means 51, 52, 54, 55 Current sensor

Claims (3)

An electric motor that drives a rotating shaft of a turbocharger or a rotating shaft of a compressor,
Having 6 phases of stator windings, the 6-phase stator windings being divided and coupled into two Y-connections that are out of phase with each other by 60 degrees;
Phase abnormality detection means for detecting abnormality such as disconnection and short circuit of each phase of the stator winding;
When any phase abnormality is not detected, two Y connections are driven in six phases, and when any phase abnormality is detected, the energization drive to the Y connection including that phase is cut off and the Y phase consists only of normal phases. A driving device having switching means for driving the connection in three phases;
A turbocharger assist electric motor comprising:   The turbocharger assist motor according to claim 1, wherein the electric motor is an induction motor. The turbocharger assist motor according to claim 1, wherein the electric motor is a brushless motor in which a permanent magnet is arranged on a rotor.

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