JP2008193790A - Electric motor driver for turbocharger with electric motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve smooth stop control of a turbocharger with an electric motor. <P>SOLUTION: An electric motor driver E for the turbocharger with an electric motor supplies a motor current of each phase to a permanent magnet synchronous motor 3, which forms the turbocharger having an electric motor 2 with the turbocharger 1, and drives the motor. In this driver, a slow-OFF means 10 is provided, which makes the motor current gradually lower to the OFF stale at the time, when power assist is switched off. Furthermore, a ramp lowering and OFF means 11 where the motor current is reduced by ramp lowering and turns off the motor, or a multi-step lowering OFF means 12, which reduces the motor current in multiple steps and turns off the motor, is provided as the gradual OFF means 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor drive device for a turbocharger with an electric motor.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique for providing a turbocharger device with an electric motor that can be driven over a rotation range necessary for a turbocharger and is inexpensive and practical. Focusing on the fact that this turbocharger rotates at 10,000 to 20,000 r / min during idling, the turbocharger drives the induction motor using a simple rectangular wave that does not place a load on the waveform control over the entire rotation range.

  This power control device for a turbocharger with an electric motor implements inverter boost control that increases the output voltage of the inverter as the target rotational speed increases on the low speed rotation side of the induction motor, and increases the target rotational speed on the high speed rotation side of the induction motor. Accordingly, the converter boost control is set to increase the output voltage of the converter. This increases the flexibility of power control in the power control apparatus.

  For example, when accelerating from a stop, the electric motor operates from 10,000 to 20,000 r / min to ultra high speed rotation. At this time, first, the variable control of the power control is performed by the inverter, and then the variable control of the power control is performed by the converter, so that the rotation smoothly rises. In the case of performing intermediate acceleration, the rotation increases smoothly only by performing variable control of power control by the converter.

JP 2005-42684 A JP 2005-137106 A Yosuke Takada et al .: "220000r / min -2kW PM motor drive system for turbocharger", Proceedings of the 2004 IEEJ Industrial Application Conference Takaharu Takeshita et al .: "Sensorless brushless DC motor control based on current estimation error", Proc. Masato Ichikawa: “Sensorless control of IPMSM by estimation of extended induced voltage in rotating coordinate system”, Proceedings of Annual Conference of IEEJ Hiroshi Osawa: "High-performance V / f control of embedded magnet type PM motor", Techno Frontier Symposium 2004 Motor Technology Symposium, Japan Management Association

However, in the technique of Patent Document 1, an electric motor current (hereinafter also referred to as “motor current”) is turned off in a short time due to a stop command or speed arrival from an engine control device (hereinafter referred to as “ECU”). For this reason, the engine torque changes stepwise at the moment when the electric assist is turned off, and there is a problem that the ride comfort is deteriorated particularly in a passenger car.
The present invention has been made in view of the above-described circumstances, and an object thereof is to realize smooth stop control of a turbocharger with an electric motor.

  In order to achieve the above object, a motor drive device for a turbocharger with an electric motor according to the present invention is controlled and driven by supplying electric current of each phase to a permanent magnet synchronous motor that forms a turbocharger with an electric motor together with the turbocharger. In the motor driving apparatus, the slow OFF means for slowly turning off the motor current when the electric assist is turned off is adopted.

  Further, as the slow OFF means, a ramp lowering OFF means that is turned OFF by being lowered by ramp lowering or a multistage lowering OFF means that is turned OFF by being reduced in multiple stages is adopted.

  According to the present invention, when the stop command from the ECU or the speed is reached, the motor current at the time when the electric assist is turned off is slowly reduced by the slow OFF means so that the engine torque is turned off at the moment when the electric assist is turned off. Therefore, it is possible to maintain a good ride comfort especially in an internal combustion engine automobile including a passenger car. In this way, smooth stop control of the turbocharger with electric motor is realized.

Hereinafter, an embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected to the same function over each figure, and duplication of description is avoided.
FIG. 1 is a block diagram showing an electric motor drive device (hereinafter referred to as “motor driver”) E for the turbocharger 2 with electric motor according to the present embodiment. In FIG. 1, a turbocharger 1 includes a turbine 1a that rotates upon receiving exhaust from an engine 5, and a compressor 1b that rotates coaxially with the turbine 1a.

  The turbocharger 2 with an electric motor is formed by a permanent magnet synchronous motor (hereinafter also referred to as “motor”) 3 that is coupled to the turbocharger 1 so as to be coaxially rotatable. The motor driver E includes a slow OFF means 10 for slowly turning off the motor current when the electric assist is turned off, in addition to the synchronous motor driving means having the booster circuit 7 and the inverter 8 as main components using the battery 6 as a power source. ing.

  The slow OFF means 10 includes a ramp lowering OFF means 11 that is reduced and turned off when the lamp is lowered, or a multistage lowering OFF means 12 that is reduced and turned off in multiple stages. The motor driver E receives speed control (speed command) from the ECU 4 with the battery 6 as a power source, and faithfully drives the motor 3 along a predetermined control pattern (see FIG. 3).

  More specifically, as the waveform generating means 28 (see FIG. 2) forming the slow OFF means 10, current control for slowly turning OFF is possible using a time constant by a combination circuit of a capacitor and a resistor (not shown). Alternatively, a ramp down using a ramp (tilt) function stored in advance in the microcomputer, or a signal that falls in multiple stages according to the relationship between the clock and the bit may be used. Alternatively, a similar slow OFF means 10 may be built in the speed controller 21.

  The motor 3 is a sensorless permanent magnet type synchronous motor in which the rotor 3a is formed of a permanent magnet and does not include a sensor for detecting the rotational position of the rotor 3a, and assists the rotation of the turbocharger 1 as an auxiliary motor. It is. As is well known, the turbocharger 1 is composed of a turbine 1a and a compressor 1b, and is attached to the engine as an auxiliary machine.

  The rotation detector 31 detects the rotation of the motor 3 using a predetermined detection method. More specifically, the rotation detector 31 detects the magnetic force of the rotor 3a with a Hall element, and detects the speed of a pulse signal that becomes one pulse (pulse indicating the position of the N pole) for each rotation of the rotor 3a. To the device 27.

  2A and 2B are explanatory diagrams of the motor driver E according to the present embodiment, in which FIG. 2A is a block diagram showing a main configuration, and FIG. 2B is a graph showing a change in a transient current operation amount Iq * when electric assist is interrupted. . As shown in FIG. 2A, the motor driver E includes a subtracter 20, a speed controller 21, a current controller 22, coordinate converters 24 and 26, a rotor position / speed estimator 23, a PWM signal generator 25, a speed. A general configuration in the case where a position sensorless system is applied to the motor 3 is mainly configured from the detector 27 and the waveform generation means 28. Further, the current detectors 9u and 9v are arranged in a path where the U, V, and W phase outputs of the inverter 8 are connected to the respective phase drive coils (not shown) of the stator 3s of the motor 3. The ECU 4 and the battery 6 are not included in either the turbocharger with motor 2 or the motor driver E as shown in FIGS.

  In FIG. 2A, Vu * is a U-phase voltage manipulated variable, Vv * is a V-phase voltage manipulated variable, Vw * is a W-phase voltage manipulated variable (hereinafter simply referred to as “voltage manipulated variable”), Iu. Is the motor U-phase current, Iv is the motor V-phase current, Id is the d-axis current, Iq is the q-axis current, Vd is the d-axis voltage, Vq is the q-axis voltage, ω is the speed (= rotation speed), and θ is the rotation angle An estimated value, * indicates a command value (operation amount). The q axis and the d axis are a two-dimensional coordinate system composed of a q axis and a d axis fixed on the rotor 3a of the motor 3. That is, the q axis is a coordinate axis set on the rotating surface of the rotor 3a in the opposing direction of the S pole and the N pole of the permanent magnet, and the d axis is a coordinate axis orthogonal to the q axis.

Here, when performing speed control as a control form of the motor driver E,
ω * receives a command from the ECU 4.
Id * receives a command from the ECU 4 or is set by the inverter 8 itself.
On the other hand, when performing current control as a control form of the motor driver E,
Iq * receives a command from the ECU 4.
Id * receives a command from the ECU 4 or is set by the inverter 8 itself.
Note that the speed controller 21 may not be provided when the original function can be exhibited only by the current control.

  The motor driver E generates a motor driving current (AC current) based on the DC voltage (power supply voltage) output from the booster circuit 7 and drives the motor 3. The booster circuit 7 is provided as necessary, such as the power efficiency of the battery 6 being low, and boosts the DC voltage supplied from the battery 6 to the inverter 8. The rotation of the motor 3 is controlled by PWM control of the inverter 8. The inverter 8 switches the DC voltage supplied from the booster circuit 7 on the basis of the PWM signal supplied from the PWM signal generator 25, thereby generating a three-phase motor drive current composed of the U phase, the V phase, and the W phase. Generate.

  The current detector 9u is provided on a U-phase connection line that connects the U-phase output end of the inverter 8 and the U-phase stator winding of the motor 3, and is a motor drive that flows from the U-phase output end to the U-phase stator winding. The current Iu is detected and input to the coordinate converter 26. On the other hand, the current detector 9v is provided on a V-phase connection line connecting the V-phase output terminal of the inverter 8 and the V-phase stator winding of the motor 3, and the V-phase stator coil is connected to the V-phase stator winding. The flowing motor drive current Iv is detected and input to the coordinate converter 26.

The subtracter 20 calculates a difference between the angular velocity target value ω * supplied from the ECU 4 as the host controller and the angular velocity estimated value ω1 output from the rotor position / speed estimator 23 as a speed error Δω, and calculates the speed controller. Input to 21.
The speed controller 21 is a kind of PID controller. A q-axis current (hereinafter referred to as “the current operation amount” corresponding to the speed error Δω is obtained by performing a predetermined proportional integral / differential operation on the speed error Δω. Iq *) (referred to as “current manipulated variable”) is calculated and input to the current controller 22.

  The current controller 22 is a d-axis current (hereinafter referred to as “current manipulated variable”) Id as a current manipulated variable that is supplied from the current manipulated variable Iq *, which is commanded by the ECU 4 and is appropriately generated by the waveform generator 28. *, Voltage operations corresponding to current operation amounts Iq * and Id * based on q-axis and d-axis currents (hereinafter also referred to as “detection currents”) Iq and Id as detection currents input from the coordinate converter 26, respectively. The q-axis and d-axis voltages (hereinafter referred to as “voltage manipulated variables”) Vq * and Vd * as quantities are calculated and input to the rotor position / speed estimator 23 and the coordinate converter 24. The current controller 22 is also a kind of PID controller, and generates voltage manipulated variables Vq * and Vd * by performing predetermined proportional integral / derivative operations on the current manipulated variables Iq * and Id *, respectively.

  The rotor position / speed estimator 23 estimates the rotation state of the motor 3 based on the detected currents Iq and Id and the voltage operation amounts Vq * and Vd *. The rotor position / speed estimator 23 includes a motor model simulating the motor 3 therein, and estimates the angular speed based on the voltage operation amounts Vq * and Vd * and the detected currents Iq and Id input to the motor model. The value ω1 and the estimated rotation angle value θ are calculated and output. The rotational angle estimated value θ estimated by such a method is input from the rotor position / speed estimator 23 to the coordinate converters 24 and 26, and the angular speed estimated value ω1 is also input to the subtractor 20.

  The coordinate converter 24 converts the voltage manipulated variables Vq * and Vd * input from the current controller 22 based on the rotation angle estimation value θ input from the rotor position / speed estimator 23 into the U phase, the V phase, and the W phase. It is converted into voltage manipulated variables Vu *, Vv *, Vw * on a three-dimensional coordinate system composed of phases. The voltage manipulated variables Vu *, Vv *, and Vw * are input to the PWM signal generator 25.

  The PWM signal generator 25 generates a PWM signal for switching the inverter 8 based on the voltage manipulated variables Vu *, Vv *, and Vw * and inputs the PWM signal to the inverter 8. At this time, the inverter 8 outputs a motor drive current over the entire rotation angle (360 °) of the motor 3. Then, the motor driver E continues the operation based on the sine wave energization method.

  The coordinate converter 26 uses the U-phase and V-phase motor detection currents (hereinafter also referred to as “detection currents”) Iu and Iv detected by the current detectors 9u and 9v, respectively for the q-axis and the d-axis. Detection currents Iq and Id are generated. More specifically, the coordinate converter 26 obtains the W-phase motor drive current Iw by internal calculation based on the detection currents Iu and Iv, and detects the detection current Iu on the three-dimensional coordinate system including the U-phase, V-phase, and W-phase. , Iv, Iw are subjected to predetermined coordinate transformation to obtain detected currents Iq, Id.

  The speed detector 27 is a kind of signal converter (F / V converter) that converts the pulse signal into a DC voltage corresponding to the repetition frequency, and inputs the DC voltage to the ECU 4 as an angular velocity detection value ωk.

  The waveform generation means 28 is a function included in the slow OFF means 10 (FIG. 1), and receives an instruction from the ECU 4 to generate appropriate current manipulated variables Iq * and Id * and / or the speed controller 21. To help. Specifically, in addition to being able to perform slow current control using a time constant by a combination circuit of a capacitor and a resistor (not shown), ramp down using a ramp (tilt) function stored in advance in a microcomputer, Alternatively, a signal that falls in multiple stages may be generated and used depending on the relationship between the clock and the bit. The current operation amounts Iq * and Id * generated by the waveform generation unit 28 are input to the current controller 22.

  In general rotation control of a sensorless permanent magnet type synchronous motor, the angular velocity and rotation angle of the sensorless permanent magnet type synchronous motor are estimated by some method, and the sensorless permanent magnet type synchronous motor is vector controlled based on the estimated value. Alternatively, V / f control is performed.

  On the other hand, the estimation method of the angular velocity estimation value ω1 and the rotation angle estimation value θ in the rotor position / speed estimator 23 is equivalent to the method described in Non-Patent Document 2, but Patent Document 2 and Non-Patent Document 3 , 4 disclose an estimation method of angular velocity, rotation angle and the like in rotation control of a sensorless permanent magnet type synchronous motor. Therefore, the methods disclosed in Patent Literature 2 and Non-Patent Literatures 3 and 4 may be used as the estimation methods of the angular velocity estimation value ω1 and the rotation angle estimation value θ in the rotor position / speed estimator 23.

  Next, the operation of the turbocharger with electric motor 2 configured as described above and the operation of the motor driver E will be described in detail with reference to FIG. 3 in addition to FIGS. FIG. 2 shows changes in the rotational speed of the turbocharger 2 with an electric motor. The turbocharger 2 with the electric motor increases in rotational speed when the turbine 1a is driven by the exhaust gas of the engine, while the rotational speed also increases with assistance from the motor 3.

  Assist by the motor 3 is performed to increase the rotational speed of the turbocharger 2 with electric motor at a high speed, as shown by “electric assist” shown in the figure. With the assistance of the motor 3, the rotational speed of the turbocharger 2 with the electric motor rapidly increases, for example, from a low speed rotation of less than about 10,000 r / m to a high speed rotation of more than about 100,000 r / m.

  The motor driver E drives the motor 3 by operating the motor driver E when “electric assist” is instructed by the operation instruction signal J input from the ECU 4. That is, at the time of the electric assist, the motor drive current is supplied from the inverter 8 to the motor 3 via the drive current line of each phase, and the motor 3 is rotationally driven.

  The current detectors 9u and 9v input the U-phase and V-phase motor driving currents Iu and Iv based on the motor driving current to the coordinate converter 26, and the coordinate converter 26 outputs another phase, that is, the W phase. Motor drive current Iw is calculated from U-phase and V-phase motor drive currents Iu and Iv, and three-phase (U-phase, V-phase and W-phase) motor drive currents Iu, Iv and Iw are set to the estimated rotation angle θ. By performing a coordinate conversion process using a conversion matrix including corresponding elements, a q-axis detection current Iq and a d-axis detection current Id in the q-axis-d-axis coordinate system unique to the motor 3 are generated.

  Further, at the time of this electric assist, the angular velocity target value ω * is input from the ECU 4 to the subtracter 20 and the current operation amount Id * corresponding to the target value of the detected current Id is also input from the ECU 4 to the current controller 22. . Here, the current manipulated variable Id * is set to “0”.

The subtracter 20 generates a speed error Δω by calculating a difference between the target angular speed value ω * and the estimated angular speed value ω 1 of the motor 3 input from the rotor position / speed estimator 23.
The speed controller 21 generates a current manipulated variable Iq * corresponding to the detected current Id by performing proportional integration / derivative processing on the speed error Δω.
The current controller 22 generates voltage operation amounts Vq * and Vd * corresponding to the drive voltage to be applied to the motor 3 by performing proportional integration and differentiation operations on the current operation amounts Iqs and Ids, respectively.

The rotor position / speed estimator 23 includes a q-axis detection current Iq and a voltage operation amount Vq, and a d-axis detection current Id and a voltage operation amount in a q-axis-d-axis coordinate system fixedly set on the rotor 3a of the motor 3. The angular velocity estimation value ω1 and the rotation angle estimation value θ are estimated using Vd * as an input signal.
The coordinate converter 24 uses the rotation angle estimated value θ to convert the voltage manipulated variables Vq * and Vd * into voltage manipulated variables Vu *, Vv *, V on a three-dimensional coordinate system composed of a U phase, a V phase, and a W phase. Convert to Vw *.

The PWM signal generator 25 generates a PWM signal for switching the inverter 8 based on these voltage operation amounts Vu *, Vv *, Vw * and drives the inverter 8.
On the other hand, when the operation instruction signal J issued by the ECU 4 does not instruct “electric assist” (electric assist OFF), the operation of the motor driver E is stopped and the motor 3 is idled without applying torque. Thus, in a state where the motor 3 is idling due to the electric assist OFF, the electric turbocharger 2 is rotated by the energy of the engine exhaust.

  The rotation detector 31 always outputs a pulse signal corresponding to the rotation speed of the motor 3 regardless of whether the electric assist or the electric assist is OFF. Then, the speed detector 27 converts the pulse signal into a DC voltage corresponding to the repetition frequency, so that the angular speed detection value ωk is always output to the ECU 4. This rotation detector 31 may use a Hall element or the like as a detection element, or may use a magnetoresistive element or the like.

  As shown in the graph of FIG. 2 (b), the transient current manipulated variable Iq * at the time when the electric assist is interrupted is turned off by decreasing the current manipulated variable Iq * by ramp-down as the slow OFF means 10 shown in FIG. A ramp lowering OFF means 11 is employed. Further, the ramp lowering OFF means 12 (FIG. 1) that is not limited to the ramp lowering OFF and is turned off by decreasing in multiple steps may be adopted.

  These ramp-down OFF waveform (graph (b) in FIG. 2) and multi-step falling OFF waveform (not shown) are appropriately generated by software processing using a microcomputer provided in the waveform generation means 28. The current manipulated variables Iq * and Id * may be reflected.

  Next, the operation of the motor driver E configured as described above will be described in detail with reference to FIG. FIG. 3 is a diagram showing the relationship between the change in rotational speed of the turbocharger 2 with electric motor and the motor current in one embodiment of the present invention. (A) Change in rotational speed of the turbocharger 2 with electric motor, (b) Unmeasured Motor current, and (c) slow OFF control motor current.

  As shown in FIG. 3A, the turbocharger 2 with an electric motor increases in rotational speed when the turbine 1a is driven by the exhaust gas of the engine, while the rotational speed also increases with assistance (assist) by the motor 3. . Assist by the motor 3 is performed to increase the rotational speed of the turbocharger 2 with electric motor at a high speed, as shown by “electric assist” shown in the figure. When the motor 3 electrically assists the turbocharger 1, the rotation speed of the turbocharger 2 with the electric motor is, for example, from a low speed of several thousand to about 10,000 revolutions per minute to a high speed revolution exceeding about 100,000 hundreds of revolutions per minute. It rises rapidly.

  Here, the unmeasured motor current shown in the square in the graph of FIG. 3 (b) is merely ON-OFF, and there is no problem when the electric assist is on, but when the electric assist is interrupted (point Xb). As shown in FIG. 3A, the rotational speed change is indicated by a point Xa in the graph, resulting in a non-smooth decrease in acceleration. As described above, when the rotational speed of the turbocharger 2 with electric motor decreases in a discontinuous manner, the output increase of the engine 5 also becomes discontinuous. As a specific influence, for example, the acceleration is lowered in a stepped state while the passenger vehicle is rapidly accelerating, so the ride comfort is deteriorated.

  On the other hand, according to the one-side trapezoidal (ramp) -shaped slow OFF-controlled motor current extending from the points Xc to Xd in the graph of FIG. 3C, the rotational speed change at the point Xa in the graph of FIG. It becomes possible. That is, the effect of reducing the stepped impact of the acceleration reduction accompanying the electric assist OFF is brought about. In other words, electric assist / soft-off is realized, and, for example, even when suddenly accelerating in a passenger car equipped with a turbocharger 2 with an electric motor according to the present invention, a good ride comfort is achieved without causing a torque step when the acceleration is reduced. be able to.

  More specifically, on the basis of the operation instruction signal J that is a command from the ECU 4 and the speed signal from the speed detector 27, the waveform generating means 28 specifies the point Xa shown in FIG. A waveform that slowly turns off may be output from the point Xc in (c) to the point Xd in FIG. That is, the object is achieved by executing a program that outputs a waveform that slowly turns OFF when it is recognized that it matches the control pattern stored in the microcomputer of the waveform generating means 28.

It is a block diagram which shows the structure of the electric motor drive device for turbochargers with an electric motor which concerns on this embodiment. It is explanatory drawing of the motor drive device for turbochargers with an electric motor which concerns on this embodiment, (a) The block diagram which shows a main structure, (b) The graph which shows the change of the transient electric current operation amount at the time of electric assistance interruption . In this embodiment, it is a figure which shows the relationship between the rotational speed change of the turbocharger with an electric motor, and a motor current, (a) Rotational speed change of the turbocharger 2 with an electric motor, (b) Unmeasured motor current, (c) Slow This is the motor current for OFF control.

Explanation of symbols

1 Turbocharger 2 Turbocharger with electric motor 3 Permanent magnet synchronous motor (motor)
10 slow OFF means 11 ramp lowering OFF means 12 multi-stage lowering OFF means E motor drive device for motor-equipped turbocharger (motor driver)

Claims (2)

In the motor drive device that is controlled and driven by supplying the motor current of each phase to the permanent magnet synchronous motor that forms the turbocharger with the motor together with the turbocharger,
An electric motor drive device for a turbocharger with an electric motor, comprising slow OFF means for slowly decreasing an electric motor current when the electric assist is OFF.   2. The turbocharger with an electric motor according to claim 1, wherein the slow OFF means includes a ramp lowering OFF means for decreasing and decreasing OFF by ramp lowering or a multistage lowering OFF means for decreasing OFF in multiple stages. Electric motor drive device.

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