KR20220117033A - Apparatus for controlling ldc of ev and method thereof - Google Patents

Abstract

The present invention relates to a device for controlling a low voltage DC-DC converter (LDC) of an electric vehicle and a method thereof. The present invention aims to provide a device for controlling an LDC of an electric vehicle and a method thereof, which are able to group electronic loads placed in the electric vehicle by current characteristics, monitor a required current amount for each group, limit the entry of the LDC into a burst mode based on the results of monitoring, prevent the frequent chattering of the LDC, and improve fuel efficiency of the electric vehicle. To this end, according to the present invention, the device for controlling the LDC of the electric vehicle can comprise: a current sensor measuring a current supplied to each electronic load of the electric vehicle; and a control unit grouping the electronic loads of the electric vehicle by current characteristics, monitoring a required current amount for each group, and limiting the entry of the LCD into a burst mode based on the results of monitoring.

Description

LDC control device for electric vehicle and method therefor

The present invention relates to a technology for improving fuel efficiency by controlling a low voltage DC-DC converter (LDC) provided in an electric vehicle.

In general, an electric vehicle is a vehicle driven by driving an electric motor using a high voltage battery, and is a hybrid electric vehicle (HEV), an electric vehicle (EV), a plug-in hybrid electric vehicle (PHEV), and a fuel cell electric vehicle (FCEV). ), etc.

Such an electric vehicle includes a high voltage battery for supplying driving power and an auxiliary battery for supplying operating power to an internal electric load (electrical device). At this time, when the voltage of the auxiliary battery does not exceed the standard value under the control of the controller, the low voltage DC-DC converter (LDC) connected to the auxiliary battery and the electric load lowers the high voltage of the high voltage battery to the charging voltage of the auxiliary battery ( down converting) Charge the auxiliary battery.

The auxiliary battery serves to supply operating power to electric loads such as various lamps, systems, and ECU (Electronic Control Units) as well as starting the vehicle.

Until now, lead-acid storage batteries have been mainly used as auxiliary batteries for vehicles because they can be recharged even after being completely discharged, but these lead-acid storage batteries are heavy and have low charge density. Since it is a material, it is being replaced by a 12V lithium ion battery in recent eco-friendly vehicles. However, 12V lithium-ion batteries have a fatal weakness that they cannot be recharged when overdischarged. To compensate for this, technologies to prevent overdischarge of 12V lithium-ion batteries by using an overdischarge prevention relay are being developed one after another.

The conventional LDC control technology monitors the SOC (State of Charge) of the auxiliary battery, and operates the LDC in the charging mode when the SOC of the auxiliary battery falls below the lower limit reference value to charge the auxiliary battery, and the SOC of the auxiliary battery is When the upper limit value is exceeded, the LDC is operated in a burst mode to stop charging the auxiliary battery.

This conventional LDC control technology simply determines whether to enter the burst mode of the LDC based on the SOC of the auxiliary battery without considering the current characteristics of various electric loads, so that the activation and deactivation of the LDC is repeated. There is a problem in that the fuel efficiency of electric vehicles is deteriorated due to this phenomenon.

Matters described in this background section are prepared to promote understanding of the background of the invention, and may include matters that are not already known to those of ordinary skill in the art to which this technology belongs.

In order to solve the problems of the prior art as described above, the present invention groups electric loads provided in electric vehicles by current characteristics, monitors the amount of current required for each group, and based on the monitoring result, LDC (Low voltage DC- An object of the present invention is to provide an LDC control device for an electric vehicle and a method therefor that can improve fuel efficiency of an electric vehicle by preventing frequent chattering of the LDC by limiting the burst mode entry of the DC converter).

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention not mentioned may be understood by the following description, and will be more clearly understood by the examples of the present invention. It will also be readily apparent that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the appended claims.

An LDC control apparatus for an electric vehicle according to an embodiment of the present invention for achieving the above object, the electric current sensor for measuring the current supplied to each electric load of the electric vehicle; and a control unit for grouping each electric load of the electric vehicle by current characteristics, monitoring the amount of current required for each group, and limiting the burst mode entry of a low voltage DC-DC converter (LDC) based on the monitoring result. can

An embodiment of the present invention may further include a storage unit for storing a table in which each electric load of the electric vehicle is grouped by current characteristics.

In an embodiment of the present invention, the controller may allow the LDC to enter the burst mode when the state of charge (SOC) of the auxiliary battery provided in the electric vehicle exceeds the upper limit reference value.

In one embodiment of the present invention, the control unit may group the electrical loads that continuously request an average current while causing an initial instantaneous peak current into A group.

In an embodiment of the present invention, even if the SOC of the auxiliary battery exceeds the upper limit value, if the total amount of current required of the electric loads in the group A exceeds the reference current amount, the LDC can limit the entry into the burst mode. have.

In an embodiment of the present invention, the group A may include at least one of a heater, an air conditioner, a wiper, and a lamp.

In one embodiment of the present invention, the control unit may group the electrical loads that require an average current for a reference time while causing an initial instantaneous peak current into B group.

In an embodiment of the present invention, even if the SOC of the auxiliary battery exceeds the upper limit, if any one of the electrical loads in the B group operates, the control unit may restrict the LDC from entering the burst mode.

In one embodiment of the present invention, the group B may include at least one of a washer, a transmission, and a sunroof.

An LDC control method of an electric vehicle according to an embodiment of the present invention for achieving the above object includes the steps of: measuring, by a current sensor, a current supplied to each electric load of the electric vehicle; and the control unit grouping each electric load of the electric vehicle by current characteristics, monitoring the required current amount for each group, and limiting the LDC (Low voltage DC-DC converter) from entering the burst mode based on the monitoring result. may include

An embodiment of the present invention may further include the step of storing, by the storage unit, a table in which each electric load of the electric vehicle is grouped by current characteristics.

An embodiment of the present invention may include allowing the LDC to enter the burst mode when the state of charge (SOC) of the auxiliary battery provided in the electric vehicle exceeds an upper limit reference value.

An embodiment of the present invention includes the steps of: grouping electrical loads that continuously require an average current while inducing an initial instantaneous peak current into an A group; and restricting the LDC from entering the burst mode when the total amount of current required of the electric loads in the group A exceeds the reference current even if the SOC of the auxiliary battery exceeds the upper limit reference value.

An embodiment of the present invention includes the steps of: grouping electric loads that require an average current for a reference time into a B group while inducing an initial instantaneous peak current; and restricting the LDC from entering the burst mode when any one of the electric loads in the group B operates even if the SOC of the auxiliary battery exceeds the upper limit value.

The LDC control apparatus and method for an electric vehicle according to an embodiment of the present invention as described above, group electric loads provided in the electric vehicle by current characteristics, monitor the amount of current required for each group, and based on the monitoring result By limiting the LDC (Low Voltage DC-DC Converter) from entering the burst mode, frequent chattering of the LDC can be prevented, thereby improving the fuel efficiency of the electric vehicle.

1 is an exemplary view of an electric vehicle to which an LDC control device according to an embodiment of the present invention is applied;
2 is a configuration diagram of an LDC control apparatus for an electric vehicle according to an embodiment of the present invention;
3 is an exemplary view showing a current characteristic graph for each group in a table provided in the LDC control apparatus of an electric vehicle according to an embodiment of the present invention;
4 is a flowchart of an LDC control method of an electric vehicle according to an embodiment of the present invention;
5 is a block diagram illustrating a computing system for executing an LDC control method of an electric vehicle according to an embodiment of the present invention.

Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same components are given the same reference numerals as much as possible even though they are indicated on different drawings. In addition, in describing the embodiment of the present invention, if it is determined that a detailed description of a related known configuration or function interferes with the understanding of the embodiment of the present invention, the detailed description thereof will be omitted.

In describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), (b), etc. may be used. These terms are only for distinguishing the elements from other elements, and the essence, order, or order of the elements are not limited by the terms. In addition, unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in a commonly used dictionary should be interpreted as having a meaning consistent with the meaning in the context of the related art, and should not be interpreted in an ideal or excessively formal meaning unless explicitly defined in the present application. does not

1 is an exemplary view of an electric vehicle to which an LDC control apparatus according to an embodiment of the present invention is applied.

As shown in FIG. 1 , an electric vehicle (eg, HEV) to which the LDC control device according to an embodiment of the present invention is applied includes an engine 110 , an engine clutch 120 , a motor 130 , and a transmission ( 140), a differential gear device (Differential Gear: 150), an ignition switch (160), and a high voltage battery (170), LDC (180), auxiliary battery (190), electric load (200), HCU (Hybrid Control) Unit: 210), ECU (Engine Control Unit: 220), MCU (Motor Control Unit: 230), TCU (Transmission Control Unit: 240), and BMS (Battery Management System, 250) may be included.

The engine clutch 120 controls the power between the engine 110 and the motor 130, and the ignition switch 160 starts the engine 110 or through the high voltage battery 170 connected to the motor 130, the motor ( 130) can be started, and the high voltage battery 170 supplies a voltage to the motor 130 in the EV driving mode.

When the voltage of the auxiliary battery 190 does not exceed the reference value, the LDC 180 connected to the auxiliary battery 190 and the electric load 200 applies the high voltage of the high voltage battery 170 to the auxiliary battery 190 for charging. The auxiliary battery 190 is charged by down-converting the voltage. Here, the electric load 200 is a controller power source, AVN (Audio Video Navigation) system, heating wire (seat, steering wheel, window), engine (HEV), heater, air conditioner, wiper, lamp (headlight, tail light, fog light, emergency light, interior light) , daylight), brake systems (ABS, TCS), windows, door locks, electric seats (seats, backrests), MDPS (Motor Driven Power Steering), washers, transmissions, and sunroofs may include.

The ECU 220 controls the overall operation of the engine 110 , the MCU 230 controls the overall operation of the motor 130 , and the TCU 240 controls the overall operation of the transmission 140 , respectively. Here, the ECU 220 is an engine controller and controls the operation of the engine 110 according to a control signal applied from the HCU 210 through a network.

The MCU 230 is a motor controller, and converts the DC voltage of the high voltage battery 170 to a three-phase AC voltage according to a control signal provided to the network from the HCU 210, and the output torque and speed of the motor 130 according to the required output. control Also, the MCU 230 cranks the engine 110 through the motor 130 to execute engine start-on under the control of the HCU 210 . Also, the MCU 230 includes an inverter including a plurality of power switching devices, and the power switching device may include any one of an insulated gate bipolar transistor (IGBT), a MOSFET, and a transistor.

The BMS 250 is a battery manager, and detects the current, voltage, temperature, etc. of each cell within the operating area of the high voltage battery 170 to manage the state of charge (SOC), and provides general information about the high voltage battery 170 . It is provided to the HCU 210 through the network and controls the charge/discharge voltage of the high voltage battery 170 to prevent overdischarge below the limit voltage or overcharge above the limit voltage to shorten the lifespan.

The HCU 210 is a high-level controller that controls the overall operation of the hybrid vehicle. It connects with various controllers through a network to exchange information with each other, and executes cooperative control to control the output torque of the engine 110 and the motor 130 . Control and maintain the driving by controlling the target gear ratio. In addition, the HCU 210 calculates an engine speed (Engine RPM), an engine torque (Engine Torque), an ignition angle (Ignition Angle), and the like, and gives a command to the ECU 220 .

2 is a configuration diagram of an LDC control apparatus for an electric vehicle according to an embodiment of the present invention.

As shown in FIG. 2 , the LDC control apparatus 100 for an electric vehicle according to an embodiment of the present invention may include a storage unit 10 , a current sensor 20 , and a control unit 30 . At this time, according to a method of implementing the LDC control apparatus 100 for an electric vehicle according to an embodiment of the present invention, each component may be combined with each other to be implemented as one, or some components may be omitted.

Looking at each of the components, first, the storage unit 10 groups the electric load 200 provided in the electric vehicle by current characteristics, monitors the required current amount for each group, and based on the monitoring result, LDC ( 180), various logics, algorithms, and programs required in the process of limiting the burst mode entry can be stored. Here, the burst mode means that the internal pulse width modulation (PWM) of the LDC 180 is turned OFF so that the voltage conversion is not performed so that the power consumption becomes 0.

The storage unit 10 may include a table in which the electric load 200 provided in the electric vehicle is grouped by current characteristics. Such a table is shown in [Table 1] below as an example.

1st group 2nd group 3rd group 4th group Always (average) without peak current Anytime a peak current occurs (peak) Moment when no peak current occurs (average) The moment at which the peak current occurs (peak) - Controller power
- AVN system
- hot wire
- engine - Heater/Air Conditioner
- wiper
- lamp - brake
- Windows
- Electric seat
- MDPS - washer
- gearbox
- Sunroof

Current graphs for the first group, the second group, the third group, and the fourth group specified in Table 1 are as shown in FIG. 3 . In [Table 1], four groups are exemplified for better understanding, but the number of groups may vary according to the intention of the designer.

3 is an exemplary diagram illustrating a current characteristic graph for each group in a table provided in the LDC control apparatus of an electric vehicle according to an embodiment of the present invention.

In FIG. 3, (a) is a current characteristic graph for the first group, and shows a state in which an average current is continuously supplied to the electric load included in the first group. (b) is a current characteristic graph for the second group, showing a state in which the peak current is temporarily supplied to the electric load included in the second group and then the average current is continuously supplied thereafter. (C) is a current characteristic graph for the third group, and shows a state in which an average current is supplied to the electric load included in the third group for a predetermined time. (d) is a current characteristic graph for the fourth group, showing a state in which the peak current is temporarily supplied to the electric load included in the fourth group and then the average current is supplied for a certain time thereafter.

The storage unit 10 may store reference current amount information used to determine whether the LDC 180 enters the burst mode for each group.

The storage unit 10 may store an algorithm used to measure the SOC of the auxiliary battery 190 .

The storage unit 10 includes a flash memory type, a hard disk type, a micro type, and a card type (eg, an SD card (Secure Digital Card) or XD card (eXtream Digital) Card)), RAM (Random Access Memory), SRAM (Static RAM), ROM (Read-Only Memory), PROM (Programmable ROM), EEPROM (Electrically Erasable PROM), magnetic memory (MRAM) , a magnetic RAM), a magnetic disk, and an optical disk type memory may include at least one type of storage medium.

The current sensor 20 may measure the current supplied to each electric load 200 provided in the electric vehicle for each group or individually on the table stored in the storage unit 10 . Also, the current sensor 20 may measure a charging current used to calculate the SOC of the auxiliary battery 190 . Such a current sensor 20 may measure a current in various ways that are generally well known as a well-known technique.

The control unit 30 may perform overall control so that each of the components can perform their functions normally. The controller 30 may be implemented in the form of hardware, or may be implemented in the form of software, or may be implemented in the form of a combination of hardware and software. Preferably, the control unit 30 may be implemented as a microprocessor, but is not limited thereto.

In particular, the controller 30 groups the electric load 200 provided in the electric vehicle by current characteristics, monitors the amount of current required for each group, and enters the burst mode of the LDC 180 based on the monitoring result. Various controls can be performed in the process of limiting.

Hereinafter, the operation of the control unit 30 will be described in detail.

The control unit 30 may detect the SOC of the auxiliary battery 190 based on the charging current of the auxiliary battery 190 measured by the current sensor 20, and when the detected SOC exceeds the upper limit reference value, the LDC ( 180) is operated in the burst mode, and when the detected SOC does not exceed the lower limit reference value, the LDC 180 may be operated in the charging mode.

On the other hand, even if the SOC of the auxiliary battery 190 exceeds the upper limit in this way, the controller 30 prevents the LDC 180 from entering the burst mode based on the amount of current required for each group on the table stored in the storage 10 . can be limited

As an example, the control unit 30 controls the second group (a group including electrical loads that continuously require an average current while causing an initial instantaneous peak current). When the total required current of the electrical loads exceeds the reference current, 190), even if the SOC exceeds the upper limit reference value, it is possible to limit the burst mode entry of the LDC (180).

As another example, when any one of the electrical loads in the fourth group (the group including the electrical loads that induce the initial instantaneous peak current and require the reference time average current) the controller 30 operates, the auxiliary battery 190 Even if the SOC of the upper limit exceeds the reference value, it is possible to limit the burst mode entry of the LDC (180).

4 is a flowchart of an LDC control method of an electric vehicle according to an embodiment of the present invention.

First, the current sensor 20 measures the current supplied to each electric load of the electric vehicle (401).

Thereafter, the control unit 30 groups each electric load of the electric vehicle by current characteristics, monitors the required current amount for each group, and restricts the LDC 180 from entering the burst mode based on the monitoring result (402) . At this time, the control unit 30 groups the electrical loads continuously demanding the average current while causing the initial instantaneous peak current into group A, and even if the SOC of the auxiliary battery exceeds the upper limit value, the total of the electrical loads in the group A When the amount of current required exceeds the amount of reference current, it is possible to limit the LDC from entering the burst mode. In addition, the control unit 30 groups the electrical loads that require the average current during the reference time while causing the initial instantaneous peak current into the B group, and even if the SOC of the auxiliary battery exceeds the upper limit, the electrical loads in the B group If any one of them works, it can limit the LDC's entry into burst mode.

5 is a block diagram illustrating a computing system for executing an LDC control method of an electric vehicle according to an embodiment of the present invention.

Referring to FIG. 5 , the LDC control method of an electric vehicle according to an embodiment of the present invention described above may be implemented through a computing system. The computing system 1000 includes at least one processor 1100 , a memory 1300 , a user interface input device 1400 , a user interface output device 1500 , a storage 1600 connected through a system bus 1200 , and A network interface 1700 may be included.

The processor 1100 may be a central processing unit (CPU) or a semiconductor device that processes instructions stored in the memory 1300 and/or the storage 1600 . The memory 1300 and the storage 1600 may include various types of volatile or nonvolatile storage media. For example, the memory 1300 may include a read only memory (ROM) 1310 and a random access memory (RAM) 1320 .

Accordingly, the steps of a method or algorithm described in connection with the embodiments disclosed herein may be directly implemented in hardware, a software module executed by the processor 1100 , or a combination of the two. A software module may be a storage medium (i.e., memory 1300 and/or It may also reside in storage 1600 . An exemplary storage medium is coupled to the processor 1100 , the processor 1100 capable of reading information from, and writing information to, the storage medium. Alternatively, the storage medium may be integrated with the processor 1100 . The processor and storage medium may reside within an application specific integrated circuit (ASIC). The ASIC may reside within the user terminal. Alternatively, the processor and storage medium may reside as separate components within the user terminal.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains.

Therefore, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

10: storage
20: current sensor
30: control unit

Claims (16)

a current sensor for measuring the current supplied to each electric load of the electric vehicle; and
A control unit for grouping each electric load of the electric vehicle by current characteristics, monitoring the amount of current required for each group, and limiting the burst mode entry of a low voltage DC-DC converter (LDC) based on the monitoring result
An LDC control device for an electric vehicle comprising a.
The method of claim 1,
A storage unit for storing a table in which each electric load of the electric vehicle is grouped by current characteristics
LDC control device of the electric vehicle further comprising a.
The method of claim 1,
The control unit is
The LDC control device of an electric vehicle, characterized in that allowing the LDC to enter the burst mode when the SOC (State of Charge) of the auxiliary battery provided in the electric vehicle exceeds the upper limit reference value.
4. The method of claim 3,
The control unit is
Even if the SOC of the auxiliary battery exceeds the upper limit, if the total amount of current required of the electric loads in the group A exceeds the reference current, the LDC control device of the electric vehicle, characterized in that the LDC entry into the burst mode is restricted.
5. The method of claim 4,
The control unit is
An LDC control device for electric vehicles, characterized in that the electrical loads that continuously require an average current while causing an initial instantaneous peak current are grouped into A group.
5. The method of claim 4,
The A group is
An LDC control device for an electric vehicle including at least one of a heater, an air conditioner, a wiper, and a lamp.
4. The method of claim 3,
The control unit is
Even if the SOC of the auxiliary battery exceeds the upper limit value, if any one of the electric loads in the B group operates, the LDC control apparatus of the electric vehicle, characterized in that the LDC entry into the burst mode is restricted.
8. The method of claim 7,
The control unit is
An LDC control device for an electric vehicle, characterized in that the electric loads that require the average current during the reference time while causing the initial instantaneous peak current are grouped into B group.
8. The method of claim 7,
The B group is
An LDC control device for an electric vehicle including at least one of a washer, a transmission, and a sunroof.
measuring, by a current sensor, a current supplied to each electric load of the electric vehicle; and
controlling, by a control unit, grouping each electric load of the electric vehicle by current characteristics, monitoring the amount of current required for each group, and limiting the entry of a low voltage DC-DC converter (LDC) into burst mode based on the monitoring result
LDC control method of an electric vehicle comprising a.
11. The method of claim 10,
Storing, by a storage unit, a table in which each electric load of the electric vehicle is grouped by current characteristics
LDC control method of an electric vehicle further comprising a.
11. The method of claim 10,
The step of limiting the burst mode entry of the LDC,
Allowing the LDC to enter the burst mode when the SOC (State of Charge) of the auxiliary battery provided in the electric vehicle exceeds the upper limit reference value
LDC control method of an electric vehicle comprising a.
13. The method of claim 12,
The step of limiting the burst mode entry of the LDC,
Grouping the electrical loads that continuously require an average current while inducing an initial instantaneous peak current into an A group; and
Even if the SOC of the auxiliary battery exceeds the upper limit, if the total amount of current required of the electric loads in the group A exceeds the reference current, limiting the LDC from entering the burst mode
LDC control method of an electric vehicle comprising a.
14. The method of claim 13,
The A group is
An LDC control method of an electric vehicle including at least one of a heater, an air conditioner, a wiper, and a lamp.
13. The method of claim 12,
The step of limiting the burst mode entry of the LDC,
Grouping the electrical loads that require an average current for a reference time while inducing an initial instantaneous peak current into a B group; and
Even if the SOC of the auxiliary battery exceeds the upper limit, if any one of the electrical loads in the B group operates, restricting the LDC from entering the burst mode
LDC control method of an electric vehicle comprising a.
16. The method of claim 15,
The B group is
An LDC control method of an electric vehicle including at least one of a washer, a transmission, and a sunroof.

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