KR20180013112A - Method for controlling multi-phase motor, controlling apparatus thereof and mild hybrid system having the same - Google Patents

Abstract

A multiphase motor control apparatus is provided. The multiphase motor control apparatus includes an inverter for connecting a plurality of three-phase windings independently of each other to form at least two neutral points, receiving DC power from a power supply unit and converting the AC power into AC power and applying the AC power to the polyphase motor, And a plurality of current sensors provided in the plurality of current sensors for detecting currents flowing in the plurality of three phases, wherein the controller corrects the current value detected by the normal current sensor when at least one of the plurality of current sensors fails, The current value of the current sensor is detected.

Description

TECHNICAL FIELD [0001] The present invention relates to a control method for a polyphase motor, a control device thereof, and a mild hybrid system including the same. BACKGROUND OF THE INVENTION [0002]

The present invention relates to a multiphase motor control method, a control apparatus thereof, and a mild hybrid system including the same.

Generally, a hybrid vehicle in a broad sense means to drive a vehicle by efficiently combining two or more kinds of power sources. In most cases, an engine that obtains a rotational force by burning fuel (fossil fuel such as gasoline) And is generally called a hybrid electric vehicle (HEV).

On the other hand, a vehicle is provided with a starter motor for driving the engine and an alternator for generating electric power using the rotational force of the engine. At this time, the ignition switch is connected to the power source of the battery by the operation of the driver at the start of the vehicle, and the power generated by the start motor is supplied to the starter motor to start the engine by rotating the engine.

In contrast to this, the alternator is connected to the driving part of the engine, and the rotor is rotated in the state where the magnetic field is formed through the driving force of the engine, so that AC power is generated and the battery is charged using the rectifying device or the like.

Both the starter motor and the alternator are structured by a stator and a rotor, and their structures are very similar. The starter motor and the alternator can operate as a generator or a motor depending on whether a power is applied or a power is applied.

Recently, researches on the structure of a belt-driven starter generator (BSG) capable of acting as a starter motor and an alternator in a single structure are actively conducted.

In the case of a motor applied to a conventional mild hybrid system, there is no method for fault diagnosis of the sensor itself, and there is no way to drive the motor in the fault state of the sensor.

An embodiment of the present invention is to provide a multiphase motor control method capable of realizing a normal operation even when a current sensor fails, a control device thereof, and a mild hybrid system including the same.

According to an aspect of the present invention, there is provided an inverter including a plurality of three-phase windings connected independently of each other to form at least two neutral points, a DC power supplied from a power supply unit and converted into AC power to be applied to the polyphase motor, And a plurality of current sensors respectively installed between the neutral point and the inverter to detect a current flowing in the plurality of three phases, wherein the controller includes a current sensor The present invention also provides a control apparatus for a multiphase electric motor which detects a current value of a faulty current sensor based on a current value detected by a current sensor.

The plurality of three-phase windings include three phases of x, y, z and three phases of u, v, w, and the plurality of current sensors include at least two windings of x, y, And a plurality of current sensors may include at least two windings of the u, v and w phases and a second sensing unit in which two current sensors are installed between the inverters. have.

At this time, the controller detects a voltage command value input to the inverter as a current value detected by a normal current sensor when any one of the first sensing unit and the second sensing unit fails, The voltage command value input to the inverter that can be obtained through the current value of the inverter can be estimated.

In this case, the controller may further include a d-q axis converter and a current controller to obtain a voltage command value applied to the inverter as the current value.

According to another aspect of the present invention, there is provided a 48 V mild hybrid system including the above-described multi-phase motor control apparatus.

According to still another aspect of the present invention, there is provided a method of driving a three-phase motor, wherein a plurality of three-phase windings are connected independently of each other to form at least two neutral points, and at least two windings of the x, y, z phases and two current sensors Determining a failure of the first sensing unit to be installed and at least two of the windings of the u, v, w phases and the second sensing unit in which two current sensors are installed between the inverters, And estimating a current value of the faulty current sensor based on the current value detected by the normal current sensor when any one of the faulty units fails.

At this time, the estimating step includes the steps of: transforming the coordinates of the three-phase variable of the coordinate system to the current value detected by the normal current sensor; Transforming the coordinate-converted three-phase variable into an inverter voltage command value through a current controller, and converting the generated inverter voltage command value into a predetermined angle to estimate an inverter voltage command value of the faulty current sensor .

According to another aspect of the present invention, a plurality of three-phase windings are connected independently of each other to form at least two neutral points, and at least two windings of the x, y, z phases and two current sensors Determining a failure of the first sensing unit, the second sensing unit having at least two windings of the u, v, w phases and the two current sensors between the inverters, and a step of detecting a failure of the first sensing unit and the second sensing unit, The inverter having the normal current sensor generates the inverter voltage command value with the detected current value to drive the inverter, and when either one of the first sensing unit and the second sensing unit fails And a step of non-driving the inverter equipped with the faulty current sensor.

A multiphase motor control method, a control device thereof, and a mild hybrid system including the same include three phases of x, y, and z, and three phases of u, v, and w, , The plurality of current sensors are provided with at least two windings of the x, y, and z phases and two current sensors provided between the inverters so that a failure occurs in the two current sensors and only two current sensors can be used It is possible to operate by the hybrid function using two normal current sensors.

1 is a schematic view showing a mild hybrid system including a multiphase motor control apparatus according to an embodiment of the present invention.
2 is a schematic view showing a multiphase motor control apparatus according to an embodiment of the present invention.
3 is a graph showing the coordinates of each phase in the multiphase electric motor of the multiphase electric motor control apparatus according to the embodiment of the present invention.
4 is a graph showing a current waveform of the multiphase motor control apparatus according to an embodiment of the present invention.
5A and 5B are flow charts illustrating a process of generating an inverter voltage command in the normal operation of the current sensor of the multiphase motor control apparatus according to the embodiment of the present invention. Is a flowchart showing a process of generating an inverter voltage command when a current sensor fails on the u and v phases of the multiphase motor control apparatus according to an embodiment of the present invention.
6 is a graph showing voltage waveforms on the dq axis at the time of failure of the current sensor on the multiphase motor control device u, v according to the embodiment of the present invention.
7 is a flowchart showing a control method of a control apparatus for a polyphase motor according to an embodiment of the present invention.
8 is a flowchart showing a modification of the control method of the control apparatus for a polyphase motor according to the embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same or similar components are denoted by the same reference numerals throughout the specification.

In this specification, the terms "comprises" or "having" and the like refer to the presence of stated features, integers, steps, operations, elements, components, or combinations thereof, But do not preclude the presence or addition of one or more other features, integers, steps, operations, components, parts, or combinations thereof. Also, where a section such as a layer, a film, an area, a plate, or the like is referred to as being "on" another section, it includes not only the case where it is "directly on" another part but also the case where there is another part in between. On the contrary, where a section such as a layer, a film, an area, a plate, etc. is referred to as being "under" another section, this includes not only the case where the section is "directly underneath"

1 is a schematic view showing a mild hybrid system including a multiphase motor control apparatus according to an embodiment of the present invention. 2 is a schematic view showing a multiphase motor control apparatus according to an embodiment of the present invention.

1, a 48 V mild hybrid system 1 including a multiphase motor control apparatus 3 according to an embodiment of the present invention includes a hybrid control unit (HCU) 9, a polyphase motor control unit A converter 13, an engine 5, a 12 V battery 17, a 48 V battery 15, and an electric field load 19, as shown in FIG.

Meanwhile, in one embodiment of the present invention, a belt-driven starter generator (BSG) is a 48 V mild hybrid system 1, and the multiphase electric motor 7 and the engine 5 are connected via a belt.

The 48 V mild hybrid system 1 including the polyphase electric motor 7 according to the embodiment of the present invention converts the battery DC electric power into the polyphase AC power through the inverter 11 at the time of traveling the vehicle, 7).

In contrast, at the time of deceleration, the inverter 11 receives the polyphase AC power, converts it into DC power, charges the 48 V battery 15, and supplies the 12 V battery 17 through the DC-DC converter 13, So that electricity can be supplied in accordance with the voltage used in the electric field load 19. [

Meanwhile, in one embodiment of the present invention, the host controller 9 is a top-level controller that controls each of the lower controllers (not shown), sets the hybrid operation mode, and controls the entire vehicle.

At this time, each of the lower controllers is connected to the high-speed CAN communication line around the host controller 9 to exchange information with each other, and the host controller can generate necessary power or torque command to the belt-driven start generator.

2, the multiphase motor control apparatus 3 according to the embodiment of the present invention assists the torque generated in the engine 5 in order to improve the fuel consumption rate according to the running state of the vehicle, A multiphase electric motor 7, an inverter 11, and a controller 30. [

Referring to FIG. 2, in one embodiment of the present invention, the inverter 11 includes x, y, z, u, v, w phases, which may be connected in parallel with each other. At this time, the inverter 11 can convert the DC power supplied from the converter 13 to AC power and supply it to the polyphase motor 7. [

In addition, in one embodiment of the present invention, the inverter 11 can convert AC power generated by the polyphase motor 7 into DC power and supply it to the converter 13.

Meanwhile, in the embodiment of the present invention, when the converter 13 converts the AC power supplied from the power supply unit to DC power and transmits the DC power to the inverter 11, the inverter receives the DC power from the converter, And switches according to the switching operation signal. At this time, the controller 30 can charge or discharge the 48 V battery 15 through the control of the inverter 11 according to the torque command.

Meanwhile, in the embodiment of the present invention, the polyphase electric motor 7 is a field winding type motor, and the magnetic flux of the rotor can be controlled through current control of the rotor. Also, in the multiphase electric motor 7, a plurality of three-phase windings may be connected to each other independently to form at least two neutral points. At this time, the polyphase electric motor 7 may be a 6-phase AC synchronous motor having x, y, z, u, v, w phase coils, but is not limited thereto.

The polyphase electric motor 7 may include a first neutral point NP1 connected to the x, y and z phases and a second neutral point NP2 connected to the u, v and w phases. At this time, the first neutral point (NP1) and the second neutral point (NP2) can be separated independently from each other.

3 is a graph showing the coordinates of each phase in the multiphase electric motor of the multiphase electric motor control apparatus according to the embodiment of the present invention. 4 is a graph showing a current waveform of the multiphase motor control apparatus according to an embodiment of the present invention.

3, the phase difference between the voltages on the x, y, and z phases and the voltages on the u, v, and w phases is 120 degrees and the phase difference between the voltages of the x phase and the u phase, the y phase and the v phase, 30 degrees, but the phase difference of 30 degrees and 120 degrees can be changed to the design value of the drive motor.

Also, in an embodiment of the present invention, the currents in the xyz axis and the uvw axis of the current sensor may be sinusoidal with a phase difference of 30 degrees.

Referring to FIG. 4, in one embodiment of the present invention, the polyphase electric motor 7 shows a current waveform having a 30-degree asymmetric structure.

Ix, Iy, Iz, Iu, Iv, and Iz in the embodiment of the present invention are expressed by the following equations.

Im is the instantaneous current of the polyphase electric motor 7,? _S is the frequency, and t is the time.

2, in one embodiment of the present invention, the current sensor signal processing for driving the multiphase electric motor 7 includes a polyphase motor having two independent neutral points, a first neutral point NP1 and a second neutral point NP2, Four current sensors 31, 33, 35, and 37 can be disposed on x, y, u, and v for phase current control.

That is, the two current sensors 31 and 33 detect the current flowing between the first neutral point NP1 of the polyphase motor 7 and at least two of the x, y and z phases of the inverter 11, , and y. The two current sensors 35 and 37 are used to detect the current flowing between the second neutral point NP2 of the polyphase electric motor 7 and at least two of the u, v and w phases of the inverter 11, u , v, but not limited thereto.

In the embodiment of the present invention, four current sensors 31, 33, 35 and 37 are used to detect currents flowing on the respective phases x, y, z, u, v and w of the six phases of the polyphase electric motor 7 This makes it possible to control the normal multiphase electric motor 7 by the characteristic that the current sum of the three phases (x, y, z phase and u, v, w phase) is always 0 as in the following equation even if four current sensors are used .

Here, Ix is a current on x phase, Iy is a current on y phase, Iz is current on z phase, Iu is current on u phase, Iv is current on v phase, and Iw is current on w phase. Due to this characteristic, currents of z and w phases can be detected using only the current sensors 31, 33, 35, and 37 provided in the four phases of x and y phases and u and v, respectively.

The controller 30 uses the switching element (not shown) of the inverter 11 to supply the polyphase voltage of the polyphase motor 7 and controls the voltage and the current. At this time, the proper inverter 11 is switched according to the precise position of the rotor, so that the generated torque of the polyphase motor 7 has a uniform constant value.

Meanwhile, in one embodiment of the present invention, the controller 30 controls the three-phase current control variables Ixyz and Iuvw inputted using the coordinate transformation based on the vector control technique and the sensor control signals Ixyz and Iuvw based on the rotation speeds of the polyphase motor 7, (?) is converted into a dq axis current signal through a dq axis converter and converted into a dq axis voltage signal using a current controller (not shown), and three phase voltage control variables Vxyz and Vuvw Can be generated.

The multiphase motor control apparatus 3 according to the embodiment of the present invention can control the currents of the respective phases (x, y, z, u, v, w phases) when there is no failure of the current sensors 31, The controller 30 performs normal multiphase motor control so that the hybrid function can be normally operated.

5A and 5B are flow charts illustrating a process of generating an inverter voltage command in the normal operation of the current sensor of the multiphase motor control apparatus according to the embodiment of the present invention. Is a flowchart showing a process of generating an inverter voltage command when a current sensor fails on the u and v phases of the multiphase motor control apparatus according to an embodiment of the present invention. 6 is a graph showing voltage waveforms on the dq axis at the time of failure of the current sensor on the multiphase motor control device u, v according to the embodiment of the present invention.

5 (a), the multiphase motor control apparatus 3 according to the embodiment of the present invention measures the currents of the x and y phases when the current sensors 31, 33, 35, and 37 fail, The xyz-axis inverter voltage command (Vxyz) can be generated through the coordinate conversion and the current controller for the three-phase variable in the xyz coordinate system.

5 (b), in the embodiment of the present invention, the currents of the u and v phases are measured and the uvw axis inverter voltage command (Vuvw) is obtained through the coordinate conversion and the current controller for the three-phase variable of the uvw coordinate system Can be generated.

The multiphase motor control apparatus 3 according to the embodiment of the present invention is configured such that the current sensors 35 and 37 connected on u and v among the four current sensors 31, 33, 35 and 37 are all faulty, Even when the multiphase electric motor 7 can not be controlled, the hybrid operation can be performed.

When the two current sensors 35 and 37 among the four current sensors 31, 33, 35, and 37 are determined to be faulty, the multi-phase motor control apparatus 3 according to the embodiment of the present invention performs the phase change operation At this time, the current value of the phase in which the failure of the current sensor occurs can be estimated from the current values of the other two phases detected from the remaining normal current sensors.

Therefore, the normal operation is performed by controlling the polyphase motor 7 that receives the current values of the x and y phases detected by the normal current sensors 31 and 33 and the current values of the u and v phases estimated therefrom .

In the multiphase motor control apparatus 3 according to the embodiment of the present invention, the current sensors 31 and 33 on the x and y phases as the two current sensors operate normally and the current sensors 35 and 35 on the u and v , 37), it is possible to obtain the xyz-axis inverter voltage command value (Vxyz) through the coordinate conversion and the current controller for the three-phase variable (Ixyz) of the xyz coordinate system by measuring the currents of the x and y phases.

5 (c), when the current sensor of the u and v phases fails, the inverter voltage command value Vxyz on the x, y, z phase is used to control the current of the polyphase motor 7, It can be estimated by the voltage command value V'uvw.

6, in the embodiment of the present invention, the inverter voltage command value (Vdq ₁ ^s ) of the dq axis stop coordinate system generated through the coordinate conversion and the current controller for the three-phase variable Ixyz in the xyz coordinate system is set to 30 degrees The converted value is defined as the voltage command estimation value (V'dq ₂ ^s ) of the dq axis stop coordinate system for the u and v phases, and this value is converted into the three-phase coordinate system, and the three-phase voltage command value V ' uvw) can be obtained.

The multiphase motor control device 3 according to the embodiment of the present invention is a voltage command value based on the current value detected by the normal current sensors 31 and 33 and outputs the voltage values of u and v which can not be detected by the current sensor failure And the multiphase motor control for the limp home mode operation can be performed using the estimated two-phase voltage value and the remaining two-phase voltage values detected by the normal current sensor.

That is, when the current sensor fails, the output of the high voltage / low voltage battery results in the discharge of the battery due to the failure of charging the battery. However, the multiphase motor control apparatus 3 according to the embodiment of the present invention generates the partial output So that the limp home mode operation is possible.

Meanwhile, a variant of the multiphase motor control apparatus according to an embodiment of the present invention is a variation of the multiphase motor control apparatus according to the embodiment of the present invention, in which the current sensors 31 and 33, which normally operate when the current sensors 35 and 37 on the u and v phases fail, (Vxyz) to the inverter (11), and the uvw axis inverter equipped with the current sensor operating abnormally can not drive the switching element.

At this time, the control method of the multiphase electric motor according to the embodiment of the present invention can be operated by the hybrid function without driving all of the phases x, y, z, u, v, w.

7 is a flowchart showing a control method of a control apparatus for a polyphase motor according to an embodiment of the present invention.

Referring to FIG. 7, a method of controlling a multiphase motor control apparatus according to an embodiment of the present invention includes a first sensing unit in which at least two windings of x, y, and z phases and two current sensors are installed between the inverters, and u a step (S10) of discriminating a fault of at least two windings of the windings, v and w phases and a second sensing part in which two current sensors are installed between the inverters, and a step of determining whether any one of the first sensing part and the second sensing part (Step S20) of estimating the current value of the failed current sensor with the current value detected by the normal current sensor.

In an embodiment of the present invention, the estimating step S20 includes a coordinate transformation step S21 for the three-phase variable of the coordinate system as a current value detected by the normal current sensor, a three- A voltage command value generating step (S23), and a converting step (S25) of converting the generated inverter voltage command value into a predetermined angle to estimate an inverter voltage command value of the faulty current sensor.

8 is a flowchart showing a modification of the control method of the control apparatus for a polyphase motor according to the embodiment of the present invention.

8, a variation of the method for controlling a multiphase motor control apparatus according to an embodiment of the present invention includes at least two windings of x, y, and z phases and a first current sensor (S110) of detecting a failure of a sensing unit and at least two windings of the u, v, w phases and a second sensing unit provided with two current sensors between the inverters, a first sensing unit and a second sensing unit The inverter having the normal current sensor generates the inverter voltage command value with the detected current value to drive the inverter (S120), and the step of selecting either one of the first sensing unit and the second sensing unit In case of failure, the inverter equipped with the failed current sensor may include a step of not driving (S130).

At this time, the method of controlling a multiphase motor according to an embodiment of the present invention can drive a multiphase motor having a 50% output performance by driving only a normal inverter. That is, when the current sensor fails, the output of the high voltage / low voltage battery results in the discharge of the battery due to the failure of charging the battery. However, the multiphase motor control apparatus 3 according to the embodiment of the present invention generates the partial output So that the limp home mode operation is possible.

In one embodiment of the present invention, the coordinate transformation and the voltage command generation method for three phases are omitted in a general method.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

1: 48 V mild hybrid system 3: Multiphase motor control device
5: Engine 7: Multiphase motor
9: host controller 11: inverter
13: Converter 15: 48 V battery
17: 12 V battery 19: electric field load
30: Controller

Claims (8)

A control device for a polyphase electric motor in which a plurality of three-phase windings are connected to each other independently to form at least two neutral points,
An inverter that receives DC power from a power supply unit and converts the AC power into AC power and applies the AC power to the polyphase motor;
And a plurality of current sensors provided between the two neutral points and the inverter to detect a current flowing in the plurality of three phases,
Wherein the controller detects a current value of the faulty current sensor based on a current value detected by a normal current sensor when at least one of the plurality of current sensors fails. The method according to claim 1,
Wherein the plurality of three-phase windings includes three phases of x, y, z and three phases of u, v, w,
The plurality of current sensors may include a first sensing unit having at least two windings of x, y, and z phases and two current sensors provided between the inverters,
Wherein the plurality of current sensors include at least two windings of u, v, and w phases and a second sensing unit in which two current sensors are provided between the inverters. 3. The method of claim 2,
The controller detects a voltage command value input to the inverter as a current value detected by a normal current sensor when any one of the first sensing unit and the second sensing unit fails, And estimates a voltage command value to be input to the inverter that can be obtained through the value of the voltage command value. The method of claim 3,
Wherein the controller further includes a dq axis converter and a current controller to obtain a voltage command value to be applied to the inverter as the current value. A 48 V mild hybrid system comprising the multiphase motor control apparatus according to any one of claims 1 to 4. A method for controlling a polyphase electric motor in which a plurality of three-phase windings are connected to each other independently to form at least two neutral points,
At least two windings of the x, y, and z phases and a first sensing portion in which two current sensors are provided between the inverters, and at least two windings of u, v, w phases and two current sensors Determining a failure of the second sensing unit to be installed; and
And estimating a current value of the faulty current sensor based on the current value detected by the normal current sensor when any one of the first sensing unit and the second sensing unit fails. The method according to claim 6,
The estimating step
Transforming the coordinates of the three-phase variable of the coordinate system into the current value detected by the normal current sensor;
Converting the coordinate-converted three-phase variable into an inverter voltage command value through a current controller; and
And estimating an inverter voltage command value of the faulty current sensor by converting the generated inverter voltage command value into a predetermined angle. A method for controlling a polyphase electric motor in which a plurality of three-phase windings are connected to each other independently to form at least two neutral points,
At least two windings of the x, y and z phases and at least two windings of a u, v, w phase in which two current sensors are installed between the inverters and two current sensors are installed between the inverters Determining a failure of the second sensing unit;
The inverter having the normal current sensor when the first sensing unit or the second sensing unit fails may generate the inverter voltage command value using the detected current value to drive the inverter;
And when the failure occurs in any one of the first sensing unit and the second sensing unit, disabling the inverter equipped with the faulty current sensor.

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