KR20170068673A - Method for controlling inverter in mild hybrid vehicle - Google Patents

Abstract

A method of controlling an inverter in a mild hybrid vehicle according to the present invention includes: receiving a torque control command from a vehicle control unit; Calculating a first resistance value of the field winding of the motor based on the switching period of the field current control section, the field current of the motor of the starting generator, and the DC link voltage of the inverter, in accordance with the torque control command; Calculating a second resistance value of the field winding corresponding to the currently measured motor temperature based on a preset reference temperature, a resistance value measured at the reference temperature, and a currently measured motor temperature; Comparing a difference between the first resistance value and the second resistance value and a threshold value; And determining whether the field circuit between the motor and the inverter is broken or in contact with the ground based on the comparison result.

Description

METHOD FOR CONTROLLING INVERTER IN MILD HYBRID VEHICLE IN MILD HYBRID VEHICLE

The present invention relates to a method of controlling an inverter in a mild hybrid vehicle.

Generally, a hybrid electric vehicle is driven by a combination of an engine and a motor mounted on the vehicle.

Such a hybrid electric vehicle can be classified into a parallel type, a series type and a hybrid type according to the driving method of the vehicle. The hybrid electric vehicle can be classified into a mild, middle, hard, Type. At this time, the form in which the capacity of the motor is smaller than the capacity of the engine is referred to as a mild hybrid system.

The mild hybrid system uses a motor with a higher response speed than the engine in order to instantaneously obtain a high torque at the time of acceleration in the stop state of the vehicle or at the time of overtaking acceleration while the vehicle is running. The necessary torque can be supplied.

On the other hand, the inverter applied to the 48V mild hybrid system uses a magnetic flux generated by applying a current to a coil wound around a rotor of a motor in order to generate a torque according to a torque control command received from a vehicle controller (ECU) You should be able to control it to the desired value.

However, when the mechanical contact failure or disconnection of the brush and the slip ring occurs, the starting generator / inverter can not supply the electric load required by the vehicle, so that the desired torque can not be generated. As a result, there is a problem that the 48V and 12V batteries cause the discharge to continue and cause the vehicle to stop operating.

Therefore, it is necessary to detect whether there is a contact failure between a break or a brush and a slip ring in order to improve the running stability and reliability of the vehicle.

In this regard, Korean Patent Laid-Open Publication No. 10-2013-0158580 (entitled " Shift control device and method of a mild hybrid vehicle ") discloses a shift control device And the engine speed is controlled by the ISG according to the injection state of the engine.

An embodiment of the present invention provides a method of controlling an inverter in a mild hybrid vehicle that can detect disconnection of a field circuit of a starting generator for a mild hybrid and improve the stable operation and reliability of the vehicle through the emergency operation control logic do.

It should be understood, however, that the technical scope of the present invention is not limited to the above-described technical problems, and other technical problems may exist.

According to a first aspect of the present invention, there is provided an inverter control method for a mild hybrid vehicle, comprising: receiving a torque control command from a vehicle control unit; Calculating a first resistance value of the field winding of the motor based on the switching period of the field current control section, the field current of the motor of the starting generator, and the DC link voltage of the inverter, in accordance with the torque control command; Calculating a second resistance value of the field winding corresponding to the currently measured motor temperature based on a preset reference temperature, a resistance value measured at the reference temperature, and a currently measured motor temperature; Comparing a difference between the first resistance value and the second resistance value and a threshold value; And determining whether the field circuit between the motor and the inverter is broken or in contact with the ground based on the comparison result.

According to any one of the above-described means for solving the problems of the present invention, it is possible to determine whether the field circuit between the motor and the inverter is disconnected or not, by calculating the resistance value of the field winding based on the measured temperature of the motor.

In addition, it is possible to prevent the vehicle from being stopped during operation through the emergency control logic in case of disconnection or poor contact.

1 is a configuration diagram of a starting generator / inverter system of a mild hybrid vehicle according to an embodiment of the present invention.
2 is a block diagram of an inverter controller in accordance with an embodiment of the present invention.
3 is a flowchart of an inverter control method according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. In the drawings, the same reference numbers are used throughout the specification to refer to the same or like parts.

Throughout this specification, when a part is referred to as being "connected" to another part, it is not limited to a case where it is "directly connected" but also includes the case where it is "electrically connected" do.

Throughout this specification, when a member is " on " another member, it includes not only when the member is in contact with the other member, but also when there is another member between the two members.

Throughout this specification, when an element is referred to as "including " an element, it is understood that the element may include other elements as well, without departing from the other elements unless specifically stated otherwise. The terms "about "," substantially ", etc. used to the extent that they are used throughout the specification are intended to be taken to mean the approximation of the manufacturing and material tolerances inherent in the stated sense, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure. The word " step (or step) "or" step "used to the extent that it is used throughout the specification does not mean" step for.

1 is a configuration diagram of a starting generator / inverter system 1 of a mild hybrid vehicle according to an embodiment of the present invention.

The starter generator / inverter system 1 of the mild hybrid vehicle according to an embodiment of the present invention includes a starter generator 110, an inverter 120, a 48V battery 130, a converter 140 and the like.

A starter generator 110 applied to a mild hybrid vehicle provides a starting torque for starting the engine and a generator torque for generating an AC voltage. Such a starter generator 110 is usually made of a synchronous motor (hereinafter referred to as a motor) in which field windings are wound around a rotor.

The starter generator 110 is supplied with driving power through the inverter 120 during a motor function and supplies auxiliary power of the engine and starting torque when the engine is stopped. When the starter generator 110 functions as a generator, And stores the electric energy generated when the vehicle is braked or converted.

The inverter 120 includes an inverter controller 125 for controlling the inverter 120 and includes a field current controller (power semiconductor switch) 121 for controlling the stator and the rotor of the motor included in the starter generator 110, . The inverter 120 converts the electric energy supplied from the storage device and supplies the converted electric energy to the starter generator 110 or the starter generator 110 and supplies the converted electric energy to the storage device.

At this time, the windings output from the inverter 120 and the rotor of the motor of the starter generator 110 are connected through the brush and the slip ring.

The inverter controller 125 controls the inverter 120 according to a control command received from the vehicle controller 10. [ Such a control command may be a speed control command, a torque control command, and a voltage control command.

The configuration of the inverter controller 125 will be described in more detail with reference to FIG.

2 is a block diagram of an inverter controller 125 in accordance with one embodiment of the present invention.

The inverter controller 125 according to an embodiment of the present invention includes a communication module 1251, a memory 1253, and a processor 1255.

The communication module 1251 transmits and receives data to and from the vehicle control unit 10. The communication module 1251 may include both a wired communication module and a wireless communication module. The wired communication module may be implemented by a power line communication device, a telephone line communication device, a cable home (MoCA), an Ethernet, an IEEE1294, an integrated wired home network, and an RS-485 control device. In addition, the wireless communication module can be implemented with a wireless LAN (WLAN), Bluetooth, HDR WPAN, UWB, ZigBee, Impulse Radio, 60 GHz WPAN, Binary-CDMA, wireless USB technology and wireless HDMI technology.

More preferably, the communication module 1251 can transmit and receive data through the CAN (Controller Area Network) communication with the vehicle controller 10. [

In the memory 1253, a program for controlling the inverter is stored. At this time, the memory 1253 is collectively referred to as a non-volatile storage device and a volatile storage device which keep the stored information even when power is not supplied.

For example, the memory 1253 may be a compact flash (CF) card, a secure digital (SD) card, a memory stick, a solid- A magnetic computer storage device such as a NAND flash memory, a hard disk drive (HDD) and the like, and an optical disc drive such as a CD-ROM, a DVD-ROM, etc. .

The program stored in the memory 1253 may be implemented in hardware such as software or an FPGA (Field Programmable Gate Array) or ASIC (Application Specific Integrated Circuit), and may perform predetermined roles.

The processor 1255 executes the program stored in the memory 1253. [ That is, the processor 1255 can control the inverter 120 through a program for inverter control stored in the memory 1253.

Referring again to FIG. 1, the 48V battery 130 may be a 48V lithium battery, and may include a battery management system (BMS) for managing the battery. And the 48V battery can be connected to the electrical parts for 48V battery.

The converter 140 includes a converter controller 145 for controlling the converter 140 and stores the power generated from the starter generator 110 in the battery when the engine is started. The converter 140 may be a DC-DC converter.

Converter controller 145 is for controlling converter 140 and may include components such as inverter controller 125 described in FIG.

1 and 2 according to an embodiment of the present invention may be implemented in hardware such as software or an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit) Roles can be performed.

However, 'components' are not meant to be limited to software or hardware, and each component may be configured to reside on an addressable storage medium and configured to play one or more processors.

Thus, by way of example, an element may comprise components such as software components, object-oriented software components, class components and task components, processes, functions, attributes, procedures, Routines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays, and variables.

The components and functions provided within those components may be combined into a smaller number of components or further separated into additional components.

Meanwhile, the motor of the starter generator 110 in the embodiment of the present invention receives the field current through the field current controller 121 included in the inverter 120, and the slip ring attached to the rotor, It is connected via a brush to maintain the connection.

At this time, when the contact resistance between the brush and the slip ring is increased or broken, the field current can not generate an output according to the control command in the vehicle controller 10. [ That is, when the contact failure or disconnection between the brush and the slip ring of the field winding occurs, the resistance due to the contact failure or disconnection of the brush and the slip ring becomes large, so that the inverter 120 controls the current I can not do it.

If such a vehicle can not be supplied with the required electric load, the 48V and 12V batteries will continue to be in a discharge mode, failing to supply power to the vehicle, resulting in the suspension of vehicle operation.

Therefore, it is necessary to detect in advance a contact failure or disconnection between the brush and the slip ring in order to improve the running stability and reliability of the vehicle.

Hereinafter, an inverter control method in the starting generator / inverter system 1 of the mild hybrid vehicle for solving such a configuration and problems will be described in detail.

3 is a flowchart of an inverter control method according to an embodiment of the present invention.

The inverter control method according to an embodiment of the present invention first receives a torque control command from the vehicle control unit 10 (S310). At this time, the torque control command includes a current control command for controlling the field current of the winding.

Based on the torque control command as described above, based on the switching period D of the field current controller 121, the field current I of the motor of the starter generator 110, and the DC link voltage V _{in of the} inverter, The first resistance value of the field winding is calculated (S320). The first resistance value R ₁ can be calculated by the following equation ( ₁ ).

[Equation 1]

In this case, the first resistance value R ₁ is a concept including not only the resistance value of the field winding of the motor but also the resistance value due to the contact between the brush and the slip ring. The switching period D is a period during which the field current controller 121 including the power semiconductor switch 121 should be turned on during the switching period. Further, the DC link voltage V _in of the inverter 120 may be the voltage of the 48 V battery.

On the other hand, since the actual application rate is difficult to measure, the application rate value output from the inverter controller 125 can be applied.

Next, on the basis of a predetermined reference temperature (T _init), the reference temperature (T _init), a resistance value (R _init) and motor temperature (T _mot) of the current measured start-up generator 110 is measured at the current measurement The second resistance value R ₂ of the field winding corresponding to the motor temperature T _mot is calculated (S330). The second resistance value R ₂ can be calculated by the following equation ( ₂ ).

&Quot; (2) "

At this time, the predetermined reference temperature T _init may be 20 degrees as an example of application.

Next, the field between the first resistance (R1) and a second resistance (R ₂₎ different from the threshold value (R _{error, set)} the comparison and (S340), the motor and the inverter 120 based on the comparison result of the It is judged whether the circuit is disconnected or not.

Specifically, the absolute value of the difference between the first resistance value R1 and the second resistance value R2 can be compared with the threshold value R _{error, set} as shown in Equation 3 below.

&Quot; (3) "

At this time, the threshold value R _{error, set} may be set based on the resistance value difference between the maximum temperature and the minimum temperature of the motor, and the magnitude of the threshold value R _{error, set} may vary depending on the environmental condition specification of the motor . ≪ / RTI >

Based on the result of the comparison, it is possible to determine whether the motor of the startup generator 110 and the inverter 120 are disconnected or in contact with each other.

Specifically, when the above-mentioned expression (3) is satisfied as a result of the comparison, it is determined that the field circuit between the motor and the inverter 120 is broken or poor contact. Accordingly, the inverter controller 125 sends a warning message to the vehicle controller 10 to request coordinated control so that the vehicle can be operated with limited torque output (S350).

The inverter controller 125 changes the torque control command received from the vehicle controller 10 so as to output the maximum torque that the motor can output in the absence of the field current. That is, the inverter controller 125 may change the current control command to output the maximum torque that the motor can output in the absence of the field current (S360).

On the contrary, if the above expression (3) is not satisfied, the inverter controller 125 determines that the field circuit between the motor and the inverter 120 is not a disconnection or a contact failure, and the inverter controller 125 determines that the maximum And changes the torque control command received from the vehicle controller 10 to output the torque (S370). That is, the inverter controller 125 can change the current control command to output the maximum torque that the motor can output in the steady state.

Based on the torque control command thus changed, the torque of the motor is controlled (S380).

In the above description, steps S310 to S380 may be further divided into further steps, or combined in fewer steps, according to an embodiment of the present invention. Also, some of the steps may be omitted as necessary, and the order between the steps may be changed. In addition, the contents already described in Figs. 1 and 2 can be applied to the inverter control method of Fig. 3 even if other contents are omitted.

According to any one of the embodiments of the present invention as described above, the resistance value of the field winding is calculated based on the measured temperature of the motor, thereby determining whether the field circuit between the motor and the inverter 120 is broken have.

In addition, it is possible to prevent the vehicle from being stopped during operation through the emergency control logic in case of disconnection or poor contact.

Meanwhile, the inverter control method according to an embodiment of the present invention can also be implemented in the form of a recording medium including a computer program stored in a medium executed by the computer or a command executable by the computer. Computer readable media can be any available media that can be accessed by a computer and includes both volatile and nonvolatile media, removable and non-removable media. In addition, the computer-readable medium may include both computer storage media and communication media. Computer storage media includes both volatile and nonvolatile, removable and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. Communication media typically includes any information delivery media, including computer readable instructions, data structures, program modules, or other data in a modulated data signal such as a carrier wave, or other transport mechanism.

While the methods and systems of the present invention have been described in connection with specific embodiments, some or all of those elements or operations may be implemented using a computer system having a general purpose hardware architecture.

It will be understood by those skilled in the art that the foregoing description of the present invention is for illustrative purposes only and that those of ordinary skill in the art can readily understand that various changes and modifications may be made without departing from the spirit or essential characteristics of the present invention. will be. It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single entity may be distributed and implemented, and components described as being distributed may also be implemented in a combined form.

The scope of the present invention is defined by the appended claims rather than the detailed description and all changes or modifications derived from the meaning and scope of the claims and their equivalents are to be construed as being included within the scope of the present invention do.

1: Starting generator / inverter system for mild hybrid vehicle
10: vehicle control unit 110: starter generator
120: inverter 121: field current controller
125: inverter controller 1251: communication module
1253: memory 1255: processor
130: 48V battery 140: converter
145: converter controller

Claims (5)

A method of controlling an inverter in a mild hybrid vehicle,
Receiving a torque control command from a vehicle control unit;
Calculating a first resistance value of the field winding of the motor based on the switching period of the field current control section, the field current of the motor of the starting generator, and the DC link voltage of the inverter, in accordance with the torque control command;
Calculating a second resistance value of the field winding corresponding to the currently measured motor temperature based on a predetermined reference temperature, a resistance value measured at the reference temperature, and a currently measured motor temperature;
Comparing a difference between the first resistance value and the second resistance value and a threshold value; And
And determining whether the field circuit between the motor and the inverter is disconnection or contact failure based on the comparison result. The method according to claim 1,
Wherein the threshold value is set based on a resistance value difference at a maximum temperature and a minimum temperature of the motor. The method according to claim 1,
If it is determined that the field circuit between the motor and the inverter is disconnected or has a poor contact,
Transmitting a warning message to the vehicle control unit; And
And changing the torque control command so that the motor outputs the maximum torque that can be output in the absence of the field current. The method according to claim 1,
When it is determined that the field circuit between the motor and the inverter is not a disconnection or a contact failure,
Further comprising changing the torque control command so that the motor outputs a maximum torque that can be output. The method according to claim 1,
Wherein the first resistance value includes a resistance value of the field winding of the motor and a resistance value due to contact between the brush and the slip ring.

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