KR20160060495A - Low Voltage Converter of Electric Vehicle - Google Patents

Abstract

The present invention relates to a low voltage DC-DC converter of an electric vehicle, and the purpose of the present invention is to reduce the size of a high voltage battery and to improve reliability thereof by setting a temperature critical value of heating elements of the low voltage DC-DC converter (LDC) by means of a software means. The present invention comprises: a temperature sensor (110) which senses the temperature of the LDC and outputs voltage corresponding to the temperature; an analog to digital converter (120) which samples the output of the temperature sensor by a predetermined time unit and outputs digitalized data; a low frequency pass filter (210) which filters the output of the analog to digital converter (120) and sets a range of the sampling; and a controller (220) which collects the output data of the low frequency pass filter (210) in the sampling range set in the analog to digital converter (120) and senses a change of a critical range.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a low-

The present invention relates to a low-voltage converter of an electric vehicle, and more particularly, to a technique for determining a temperature threshold value of a heating element in a low-voltage DC-DC converter provided in a battery charging device of an electric vehicle.

Generally, a hybrid vehicle in a broad sense means driving a vehicle by efficiently combining two or more different kinds of power sources.

However, in most cases, this means a vehicle that obtains a driving force by an engine that uses a fuel to obtain a driving force and an electric motor that is driven by the power of the battery, and is generally called a hybrid electric vehicle (HEV).

In recent years, research on hybrid electric vehicles has been actively conducted in response to the demand for improving fuel efficiency and developing environmentally friendly vehicles.

The hybrid electric vehicle (hereinafter, abbreviated as 'hybrid vehicle') can form various structures using an engine and an electric motor as a power source.

Also, a high-voltage battery mounted on an electric vehicle is a main component for storing and charging a power supply, and usually has a high-voltage battery charging system for charging a high-voltage battery from an external power source.

The electric vehicle is essentially equipped with a high-voltage battery (main battery) which provides the driving power of the electric motor. During the operation of the vehicle, the high-voltage battery repeats charging or discharging and supplies necessary electric power.

Such a high-voltage battery charging system generally includes a BMS (Battery Management System) for managing charging of a high-voltage battery, a connector for connecting to an external power supply device, an external power supply and a communication interface protocol, And a communication interface for managing the communication interface.

The BMS is a component that must be provided in an electric vehicle that uses the power of the high-voltage battery as the driving force of the vehicle.

Generally, the BMS is provided with an inverter and a low voltage DC / DC converter (hereinafter referred to as "low voltage converter") so that the state of the high voltage battery can always be maintained in an optimal state. A program for carrying out the present invention is mounted.

Here, the low-voltage converter performs an output conversion between a high voltage and a low voltage, and is embedded in an on-board charger (OBC) which is a charger of a high-voltage battery.

That is, the low-voltage converter converts a high-voltage direct-current voltage from a high-voltage battery of an electric vehicle into a low-voltage direct-current voltage to charge the auxiliary battery, and monitors a full-load load of the vehicle.

In this conventional electric vehicle, the temperature value is set based on the hardware by the combination of the amplifier element and the time constant before the ADC (Analog Digital Converter).

In addition, a conventional electric vehicle uses a first low-pass filter composed of a resistor and a capacitor for noise removal.

However, there is a problem that the above-described conventional hardware configuration is vulnerable to EMC (Electro Magnetic Compatibility).

In addition, there is a problem that reliability and productivity of the high-voltage battery charger are deteriorated due to a size increase due to the hardware configuration.

It is an object of the present invention to provide a temperature threshold value of a heating element of a low voltage converter in an electric vehicle through a software means.

It is another object of the present invention to reduce the size of a high voltage battery and improve reliability by allowing a temperature threshold value of a heating element of a low voltage converter to be set through software means.

It is still another object of the present invention to improve the battery protection function of an electric vehicle by integrating an On-Board Charger (OBC) and a Battery Management System (BMS).

According to an aspect of the present invention, there is provided a low-voltage converter of an electric vehicle including: a temperature sensor for detecting a temperature of a low-voltage converter and outputting a voltage corresponding to the temperature; An analog-to-digital converter for sampling the output of the temperature sensor at predetermined time intervals and outputting the digitally converted data; A low-pass filter for filtering the output of the analog-to-digital converter to set the sampling range; And a controller for collecting output data of the low-pass filter in a sampling range set by the analog-to-digital converter and sensing a change in a threshold range.

Further, the temperature sensor includes an NTC thermistor for dividing and outputting a voltage by a resistance value varying with the temperature.

The analog-to-digital converter may vary the sampling range of the signal applied from the temperature sensor.

The control unit compares the first variation of the data calculated in the immediately preceding sampling with the current second variation using the bottom dead center or the top dead center as a reference value so that the output data of the low pass filter is added to the bottom dead center or the top dead center And judges that it is close.

The control unit is characterized in that when the first variation amount and the second variation amount are within the error range between the bottom dead center and the top dead center, the control unit cumulatively averages the data of the low pass filter in accordance with the changed sampling period .

The control unit controls the power source of the low voltage converter to be turned off when the accumulated average value is within a tolerance range of the bottom dead center and the top dead center.

The low-voltage converter is turned on when the bottom dead center is the reference when the margin is greater than the margin within the error range, and is turned on when the top dead center is the reference, when the margin is less than the margin.

According to the present invention, by setting the temperature threshold value of the heating element of the low voltage converter in the electric vehicle through software, it is possible to reduce the size of the high voltage battery and improve the reliability.

In addition, by integrating the On-Board Charger (OBC) and the Battery Management System (BMS), the battery protection function of the electric vehicle can be improved.

In addition, by increasing the data in the vicinity of the temperature threshold value of the heat generating element to detect a change in the critical range, chattering phenomenon occurring near the temperature threshold value of the heat generating element can be prevented.

1 is a configuration diagram of a low-voltage converter according to an embodiment of the present invention;
2 is a detailed circuit diagram of the temperature sensor of Fig.
3 is a detailed configuration diagram of the analog-to-digital converter of FIG.
FIG. 4 is a flowchart illustrating an operation of a low-voltage converter according to an embodiment of the present invention; FIG.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a low-voltage converter according to an embodiment of the present invention.

The low voltage converter according to the present invention is divided into a hardware unit 100 configuration and a software configuration 200 configuration.

The hardware unit 100 includes a temperature sensor 110 and an analog-to-digital converter (ADC) 120.

The software unit 200 includes a low pass filter 210 and a control unit 220. The software unit 200 may include a micro controller unit (MCU).

The temperature sensor 110 detects the temperature in the low voltage converter of the high voltage battery charger.

Here, the temperature sensor 110 may include an NTC thermistor having a negative temperature coefficient (NTC) characteristic in which the resistance value decreases as the temperature increases.

The analog-to-digital converter 120 converts the analog detection signal applied from the temperature sensor 110 into a digital signal and outputs the digital signal to the low-pass filter 210.

The analog-to-digital converter 120 samples the signal applied from the temperature sensor 110 and outputs the digitally-converted data to a low-pass filter.

At this time, the analog-to-digital converter 120 varies the sampling range of the signal applied from the temperature sensor 110 and outputs the same.

The low-pass filter 210 filters out a low-frequency region from a signal applied from the analog-digital converter 120 to remove noise.

In the present invention, the low-pass filter 210 is implemented as a recursive expression that can be computed in a computer.

In addition, the controller 220 outputs a signal for controlling the operation of the low-voltage converter in response to the data supplied from the low-pass filter 210.

The controller 220 senses a change in the critical range by increasing the data collection near the temperature threshold in the sampling range set by the analog-to-digital converter 120.

Accordingly, it is possible to prevent a chatter phenomenon occurring in the vicinity of the threshold value.

Fig. 2 shows a circuit diagram relating to the temperature sensor 110 of Fig.

The temperature sensor 110 includes a plurality of resistors R 1 to R 3, a plurality of capacitors C 1 and C 2, and an output unit 10.

The resistor R1 is connected between the input terminal of the temperature detection signal LDC_TEMP1 and the output section 10.

The capacitor C1 is connected between one end of the resistor R1 and the ground voltage terminal GND. The resistor R2 is connected between the power supply voltage terminal VCC and the other end of the resistor R1.

The resistor R3 is connected between the other end of the resistor R1 and the ground voltage terminal GND.

Also, the capacitor C2 is connected between the power supply voltage terminal VCC and the ground voltage terminal GND. One end of the output section 10 is commonly connected to one end of the resistors R1 to R3 and the other end of the output section 10 is connected to the ground voltage terminal GND.

The temperature sensor 110 having the above-described configuration changes the temperature change to a voltage corresponding to the ambient temperature and outputs it to the analog-to-digital converter 120.

FIG. 3 shows a detailed configuration diagram of the analog-to-digital converter 120 of FIG.

The analog-to-digital converter 120 includes a clock prescaler 121, an internal clock generator 122, a trigger multiplexer 123, a timing controller 124, a buffer 125, a multiplexer 126, A register 127, a sampling unit 128, and a comparison unit 129. [

The clock divider 121 divides an input clock and outputs the divided clock to the timing controller 124. The clock divider 121 may include a pre-divider.

Then, the internal clock generator 122 generates an internal clock ICLK of the analog-to-digital converter 120

The trigger multiplexer 123 multiplexes the trigger signals corresponding to the selection signal applied from the buffer 125 and outputs the multiplexed signals to the timing controller 124.

The timing control unit 124 can operate with the dividing clock applied from the clock divider 121 or with the internal clock ICLK applied from the internal clock generating unit 122. [

The timing control section 124 also supplies a signal for controlling the operation mode and the internal operation timing to the multiplexer 126 and the register (hereinafter referred to as " register ") in accordance with the signal applied from the trigger multiplexer 123 and the signal applied from the comparison section 129 127 or generates an interrupt signal.

The buffer 125 buffers the plurality of input signals AN and outputs a selection signal to the trigger multiplexer 123.

The multiplexer 126 multiplexes the plurality of input signals AN in response to the control signal applied from the timing control unit 124 and outputs the multiplexed signals to the sampling unit 128. [

The register 127 stores the conversion result of each bit of the input signal and outputs the result to the comparator 129 in correspondence with the output of the timing controller 124. [ It is preferable to use a 10-bit analog-to-digital converter 120 in the embodiment of the present invention.

The sampling unit 128 samples and holds the output of the multiplexer 126 and outputs it to the comparison unit 129. [

The comparing unit 129 compares the output of the sampling unit 128 with the output of the register 127 and outputs the result to the timing control unit 124. [

Hereinafter, the operation of the low-voltage converter according to the embodiment of the present invention will be described with reference to the flowchart of FIG. .

First, the voltage value corresponding to the temperature is measured through the temperature sensor 110 (step S1)

The degree of distribution of the voltage applied to the analog-to-digital converter 120 varies depending on the resistance value of the temperature sensor 110 which changes according to the ambient temperature.

At this time, the distribution formula of the voltage distributed by the temperature sensor 110 is expressed by the following equation (1).

Voltage distributed from the temperature sensor 110 is output to the multiplexer 126 of the analog-to-digital converter 120, which is a peripheral device incorporated in an MCU (Micro Control Unit).

The voltage distributed from the temperature sensor 110 is then output to the timing control unit 124 via the sampling unit 128 and the comparison unit 129.

The signal output from the temperature sensor 110 is used for calculation and judgment as a digital value quantized by the analog-to-digital converter 120.

For example, when the reference voltage used in the temperature sensor 110 is 5V, the minimum voltage value Q is expressed by the following equation (2).

Thereafter, the digital data output from the analog-to-digital converter 120 is output to the low-pass filter 210 and subjected to a filtering operation (step S2)

The microcontroller accumulates the digital value obtained at a predetermined time (every 1 second) period through the first low-pass filter 210, which is a recursive function that can be computed by a computer, to obtain filtered data.

At this time, the recursive equation of the low-pass filter 210 is expressed by the following equation (3).

는 추정 값 (Estimated Value) 이며,

는 직전 추정 값이고,

는 측정값이다. In the above equation (3),? Is a constant with 0 <? <1,

Is an estimated value,

Is an immediately preceding estimation value,

Is the measured value.

The larger the value of?, The larger the specific weight that the immediately preceding estimated value is reflected than the measured value.

Next, the data that is cumulatively filtered through the low-pass filter 210 is output to the control unit 220.

The control unit 220 determines a range of data applied from the low pass filter 210 using UTP (Under Temperature Protection) or OTP (Over Temperature Protection) as a reference value

That is, if it satisfies the following Equation (4), which is an equation condition of the data change amount? V1 and the current data change amount? V2 calculated in the immediately preceding sampling, it can be determined that it is close to UTP or OTP.

The control unit 220 determines whether or not the amount of change? V1 of the data calculated in the immediately preceding sampling is larger than the current data change amount? V2 as in Equation (4) above based on UTP. (Step S3)

Then, the control unit 220 determines whether the data change amount is smaller than the UTP tolerance (step S4)

If the amount of change? V1,? V2 of the data falls within the tolerance range of UTP, then the sampling unit 128 controls the sampling period to be short.

For example, the sampling unit 128 reduces the sampling time from 1 second to 0.1 seconds. Then, an average value accumulated during 100 sampling times is measured (step S5)

Thereafter, the control unit 220 determines whether the measured data is smaller than the tolerance of the UTP (step S6). If the measured data falls within the error range, the control unit 220 controls the power supply of the low voltage converter to be turned off (step S7)

On the other hand, the control unit 220 determines whether or not the amount of change? V1 of the data calculated in the immediately preceding sampling is larger than the current data variation? V2 as in Equation 4 above (step S8).

Then, the control unit 220 determines whether the data change amount is smaller than the OTP tolerance. (Step S9)

If the amounts of change of the data DELTA V1 and DELTA V2 fall within the tolerance range of the OTP, the sampling unit 128 controls the sampling period to be short since then.

For example, the sampling unit 128 reduces the sampling time from 1 second to 0.1 seconds. Then, an average value accumulated during 100 sampling is measured (step S10)

Thereafter, the control unit 220 determines whether the measured data is smaller than the tolerance of the OTP (step S11). If the measured data falls within the error range, the control unit 220 controls the power supply of the low voltage converter to be turned off (step S7).

Even when the low-voltage converter is turned off and the temperature value falls into the UTP or OTP region, it is preferable that the LDC has a margin region.

That is, the UTP low voltage converter is turned on when the margin is higher than the margin, and the low voltage converter is turned on when the margin is lower than the OTP margin.

According to the present invention, by setting the temperature threshold value of the heating element of the low voltage converter in the electric vehicle through software, it is possible to reduce the size of the high voltage battery and improve the reliability.

While the present invention has been described with reference to exemplary embodiments, 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 and modifications may be made without departing from the scope of the present invention.

10: Output section
100: Hardware section
110: Temperature sensor
120: Analog Digital Converter (ADC)
121: Clock Prescaler
122: internal clock generator
123: Trigger Multiplexer
124:
125: Buffer section
126: Multiplexer
127: Register
128: Sampling unit
129:
200: Software Department
210: Low-pass filter
220:

Claims (7)

A temperature sensor (110) for detecting a temperature of the low voltage converter and outputting a voltage corresponding to the temperature;
An analog-to-digital converter (120) for sampling the output of the temperature sensor at predetermined time intervals and outputting digitally converted data;
A low pass filter (210) for filtering the output of the analog to digital converter (120) to set the sampling range; And
And a controller (220) for collecting output data of the low pass filter (210) in a sampling range set by the analog to digital converter (120) and detecting a change in a critical range. The method according to claim 1,
The temperature sensor (110)
And an NTC thermistor for dividing and outputting the voltage by a resistance value varying according to the temperature. The method according to claim 1,
The analog-to-digital converter (120)
Wherein the sampling range of the signal applied from the temperature sensor is varied and output. The method according to claim 1,
The control unit 220,
The output data of the low-pass filter is compared with the first variation of the data calculated in the immediately preceding sampling with the bottom dead center (UTP) or the top dead center (OTP) as a reference value, Of the low-voltage converter of the electric vehicle. 5. The method of claim 4,
The control unit 220,
Wherein the data of the low-pass filter is cumulatively averaged corresponding to the changed sampling period when the first variation amount and the second variation amount are within the error range between the bottom dead center and the top dead center. 6. The method of claim 5,
The control unit 220,
And controls the power supply of the low-voltage converter to be turned off when the cumulative average value is a value within the allowable error range of the bottom dead center and the top dead center. The method according to claim 6,
The low-
(ON) when the bottom dead center is equal to or greater than a margin in the error range, and is turned ON when the top dead center is equal to or less than a margin when the top dead center is a reference.

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