KR20210115215A - Low-voltage DC Converter - Google Patents

Abstract

A low-voltage DC converter according to an embodiment of the present invention, as a low-voltage DC converter that converts electrical energy stored in a high-voltage battery in a hybrid vehicle, an electric vehicle, or a hydrogen electric vehicle to a low voltage, includes: a DC conversion circuit unit which switches DC to make the same into AC to be step-down, then rectifies the same back to DC to smooth the same; a communication unit which performs CAN communication with another device in the vehicle; and a control unit which is connected to the DC conversion circuit unit and the communication unit, to control the operation of the DC conversion circuit unit and the communication unit. The control unit, when an ignition key (IGN Key) is in an on state, controls the execution of a first mode of charging a low-voltage battery by the operation of the DC conversion circuit unit.

Description

Low-voltage DC Converter

The present invention relates to a low voltage DC converter, and more particularly, to a low voltage DC converter capable of converting electrical energy stored in a high voltage battery in a vehicle into a low voltage and supplying it to a low voltage battery.

A hybrid vehicle is provided with a low-voltage DC converter (hereinafter referred to as "LDC") that rectifies power of a high-voltage battery to produce low-voltage DC.

In other words, LDC switches direct current (DC) into alternating current (AC), boosts or steps down the alternating current using coils, transformers, and capacitance, and then rectifies it again to make direct current (DC), the voltage used in each electric load. It serves to supply electricity to the

US 10-2013-0023530 A

An object of the present invention is to provide a low voltage DC converter that operates in various modes according to an on or off state of an ignition key (IGN Key).

However, the problem to be solved by the present invention is not limited to the above-mentioned problems, and other problems not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. There will be.

A low voltage DC converter according to an embodiment of the present invention for solving the above problems is a low voltage DC converter that converts electrical energy accumulated in a high voltage battery in a hybrid vehicle, an electric vehicle, or a hydrogen electric vehicle to a low voltage, ( 1) A DC conversion circuit unit that switches direct current (DC) to make alternating current (AC) step-down and then rectifies to direct current (DC) for smoothing, (2) a communication unit that performs CAN communication with other devices in the vehicle, (3) ) connected to the DC conversion circuit unit and the communication unit includes a control unit for controlling the operation of the DC conversion circuit unit and the communication unit.

When the ignition key (IGN Key) is in an on state, the controller may control execution of the first mode of charging the low voltage battery by the operation of the DC conversion circuit unit.

The DC conversion circuit unit includes (1) an EMI filter unit for filtering high voltage power, (2) a PWM unit for switching the output of the EMI filter unit to AC according to pulse width modulation (PWM), (3) a step-down output of the PWM unit It may include a transformer unit, (4) a rectifying unit rectifying the output of the transformer unit, and (5) a smoothing unit smoothing the output of the rectifying unit.

The EMI filter unit may include a capacitor connected between an input terminal to which high voltage power is input.

The PWM unit includes (1) a first switching element having one end connected to one end of the capacitor, (2) a second switching element having one end connected to one end of the capacitor, and (3) one end connected to the other end of the first switching element and a third switching element having the other end connected to the other end of the capacitor, (4) a fourth switching element having one end connected to the other end of the second switching element and the other end connected to the other end of the capacitor, (5) first to A PWM controller for controlling on/off of the fourth switching element may be included.

The transformer unit has a primary coil having one end connected between the first switching element and the third switching element and the other end connected between the second switching element and the fourth switching element, and is disposed to be spaced apart from the primary coil. Each of the secondary coils may be included.

The rectifier may include a diode connected to the secondary coil to perform rectification.

When the ignition key (IGN Key) is in an off state, the control unit may receive a signal from a vehicle controller unit (VCU) and control the performance of the second mode of charging the low voltage battery by the operation of the DC conversion circuit unit. .

When the ignition key is in an off state and an on board charger (OBC) is being charged, the control unit may control execution of the third mode of charging the low voltage battery by the operation of the DC conversion circuit unit.

The first to third modes may be performed when the voltage of the low-voltage battery falls below a predetermined level.

The DC conversion circuit unit may charge the low voltage battery by outputting a voltage higher than the voltage of the low voltage battery in the first to third modes.

The communication unit may receive an on/off state signal of the ignition key (IGN Key).

The present invention configured as described above operates in various modes depending on the on or off state of the ignition key, thereby reducing unnecessary energy waste and reducing the lifespan of the low-voltage battery. There are advantages that can be

In addition, the present invention has an advantage in that the low voltage battery can be charged in a shorter time by outputting a voltage higher than the voltage of the low voltage battery LB from the DC conversion circuit unit 100 when each mode is performed.

The effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned may be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description. will be.

1 schematically shows a flow diagram of electrical energy in a vehicle.
2 is a schematic block diagram of a low voltage DC converter 1000 according to an embodiment of the present invention.
3 is a schematic block diagram of the DC conversion circuit unit 100 of the low voltage DC converter 1000 according to an embodiment of the present invention.
4 shows a schematic circuit of the DC conversion circuit unit 100 of the low voltage DC converter 1000 according to an embodiment of the present invention.

The above object and means of the present invention and its effects will become more apparent through the following detailed description in relation to the accompanying drawings, and accordingly, those of ordinary skill in the art to which the present invention pertains can easily understand the technical idea of the present invention. will be able to carry out In addition, in describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted.

The terminology used herein is for the purpose of describing the embodiments, and is not intended to limit the present invention. In this specification, the singular form also includes the plural as the case may be, unless otherwise specified in the text. In this specification, terms such as "include", "provide", "provide" or "have" do not exclude the presence or addition of one or more other elements other than the mentioned elements.

In this specification, terms such as “or” and “at least one” may indicate one of the words listed together, or a combination of two or more. For example, “or B” and “at least one of B” may include only one of A or B, and may include both A and B.

In the present specification, descriptions according to “for example” and the like may not exactly match the information presented, such as recited properties, variables, or values, tolerances, measurement errors, limits of measurement accuracy, and other commonly known factors. The embodiments of the present invention according to various embodiments of the present invention should not be limited by effects such as modifications including .

In this specification, when it is described that a certain element is 'connected' or 'connected' to another element, it may be directly connected or connected to the other element, but other elements may exist in between. It should be understood that there may be On the other hand, when it is mentioned that a certain element is 'directly connected' or 'directly connected' to another element, it should be understood that there is no other element in the middle.

In this specification, when it is described that a certain element is 'on' or 'adjacent' to another element, it may be directly in contact with or connected to the other element, but another element may exist in the middle. It should be understood that On the other hand, when it is described that a certain element is 'immediately on' or 'directly adjacent to' another element, it may be understood that another element does not exist in the middle. Other expressions describing the relationship between elements, for example, 'between' and 'directly between', etc. can be interpreted similarly.

In this specification, terms such as 'first' and 'second' may be used to describe various components, but the components should not be limited by the above terms. In addition, the above terms should not be construed as limiting the order of each component, and may be used for the purpose of distinguishing one component from another. For example, a 'first component' may be termed a 'second component', and similarly, a 'second component' may also be termed a 'first component'.

Unless otherwise defined, all terms used herein may be used with meanings commonly understood by those of ordinary skill in the art to which the present invention pertains. In addition, terms defined in a commonly used dictionary are not to be interpreted ideally or excessively unless specifically defined explicitly.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

1 schematically shows a flow chart of electric energy in a vehicle, and FIG. 2 is a schematic block diagram of a low voltage DC converter 1000 according to an embodiment of the present invention.

A low-voltage DC converter 1000 according to an embodiment of the present invention is, as shown in FIG. 1 , a high voltage (eg, 48V, etc.) accumulated in a high voltage battery HB in a vehicle. ) is a device that rectifies power and converts it into direct current of a low voltage (eg, 12V, etc.) and supplies it to the low voltage battery LB.

In this case, the vehicle includes a high voltage battery HB that is charged and provided with a high voltage power source, and a low voltage battery LB that is charged and provided with a low voltage power source. For example, the vehicle may be a hybrid vehicle, an electric vehicle, or a hydrogen electric vehicle, but is not limited thereto.

The high-voltage battery HB supplies high-voltage main power to an electric motor, an air conditioner, a heater, and the like in a vehicle. The low-voltage battery LB supplies auxiliary low-voltage power to a low-voltage electric load of the vehicle.

As shown in FIG. 2 , the low-voltage DC converter 1000 according to an embodiment of the present invention includes a DC conversion circuit unit 100 , an auxiliary power supply unit 200 , a communication unit 300 , and a control unit 400 . can do.

The direct current conversion circuit unit 100 is configured to output low voltage power by switching the direct current (DC) of the high voltage power source to make alternating current (AC) step-down, then rectifying the voltage back to direct current (DC) and smoothing it.

3 is a schematic block diagram of a DC conversion circuit unit 100 of a low voltage DC converter 1000 according to an embodiment of the present invention, and FIG. 4 is a low voltage DC converter 1000 according to an embodiment of the present invention. A schematic circuit of the DC conversion circuit unit 100 of

Specifically, as shown in FIG. 3 , the DC conversion circuit unit 100 includes the EMI filter unit 110 , the PWM unit 120 , the transformer unit 130 , the rectifier unit 140 , and the smoothing unit 150 , respectively. may include

The EMI filter unit 110 is configured to filter EMI (Electro Magnetic Interference) noise, and may be connected to input terminals T1 and T2 to which high voltage power is input. That is, the EMI filter unit 110 removes the noise generated from the high voltage power supply of the input terminal or cancels the noise to prevent the noise coming from the rear end from flowing into the corresponding input terminals T1 and T2. have. For example, the EMI filter unit may include a first capacitor 111 connected between the input terminals T1 and T2 as shown in FIG. 4 , but is not limited thereto.

The PWM unit 120 is connected to the EMI filter unit 110 and is configured to switch the output of the EMI filter unit 110 to alternating current (AC) according to pulse width modulation (PWM). To this end, the PWM unit 120, as shown in Figure 4, a plurality of switching elements (121 to 124), and to control the on / off (on) / off (off) of these switching elements (121 to 124) A PWM controller 125 may be included. For example, each of the switching elements 121 to 124 may be a MOSFET, and the PWM controller 125 may be a PWM driver, but is not limited thereto.

That is, one end of the first switching element 121 may be connected to one end of the first capacitor 111 , and the other end may be connected to one end of the second switching element 123 . One end of the second switching element 122 may be connected to one end of the first capacitor 111 , and the other end may be connected to one end of the fourth switching element 124 . One end of the third switching element 123 may be connected to the other end of the first switching element 121 , and the other end may be connected to the other end of the first capacitor 111 . One end of the fourth switching element 124 may be connected to the other end of the second switching element 122 , and the other end may be connected to the other end of the first capacitor.

Each of the switching elements 121 to 124 is controlled on/off according to the control signal of the PWM controller 125 , and accordingly, step-down by switching can be implemented in the PWM method. At this time, PWM is a control method for adjusting the duty cycle of ON and OFF. That is, PWM can be converted to AC with the required duty cycle through switching with respect to DC. The power converted into AC as described above is then converted back to DC through the rectifying unit 140 and the smoothing unit 150 so that the reduced DC power may be finally output.

The transformer 130 is connected to the PWM unit 120 to step-down the output of the PWM unit 120 . That is, the transformer 130 has one end connected between the first switching element 121 and the third switching element 123 as shown in FIG. 4 , and the second switching element 122 and the fourth switching element 123 are connected to each other. A primary coil 131 to which the other end is connected between the switching elements 124 and a secondary coil 132 spaced apart from the primary coil 131 may be included, respectively. At this time, secondary power obtained by stepping down the primary power applied to the primary coil 131 may be applied to the secondary coil 132 , and the secondary power may further add power converted from DC to AC according to PWM. It may be a step-down power supply.

The rectifying unit 140 is connected to the trans unit 130 to rectify the output of the trans unit 130 . That is, as shown in FIG. 4 , the rectifier 140 may include diodes 141 and 142 that are connected to the secondary coil 132 to perform rectification, and a plurality of the diodes 141 and 142 are provided. may be, but is not limited thereto.

The smoothing unit 150 is connected to the rectifying unit 140 to smooth the output of the rectifying unit 140 . That is, as shown in FIG. 4 , the smoothing unit 150 may include the inductor 151 and the second capacitor to smooth the rectified power supply closer to direct current.

The auxiliary power supply unit 200 processes the high voltage power input to the input terminals T1 and T2 and supplies it to the configuration as auxiliary power required for the operation of the communication unit 300 , the control unit 400 , and the like. For example, the auxiliary power supply 200 may supply a necessary auxiliary power to the corresponding configuration by stepping down the high voltage power including a diode, a capacitor, and the like.

The communication unit 300 performs CAN communication with other devices in the vehicle. For this purpose, it may be connected to a CAN communication interface (CAN HIGH, CAN LOW), and a signal received through the corresponding CAN communication line may be transmitted to the control unit 400 . In particular, the communication unit 300 may transmit and receive signals to and from a vehicle controller unit (VCU), an on board charger (OBC), and the like. For example, the communication unit 300 may receive a charging command signal, an on/off state signal of the ignition key (IGN Key), etc. from the VCU, etc. A signal may be received, but the present invention is not limited thereto.

The control unit 400 is connected to the DC conversion circuit unit 100 , the communication unit 300 , and the like to control the operation of the respective components. In particular, the controller 400 may control execution of the first to third modes.

The first mode is operated when the ignition key (IGN Key) is in an on state, and operates the DC conversion circuit unit 100 to charge the low voltage battery. In this case, the low voltage battery LB may be charged by outputting a voltage (eg, 14.2 ± 0.5V, etc.) higher than the voltage (eg, 12V) of the low voltage battery LB.

The second mode is activated when the ignition key (IGN Key) is in an off state and receives a signal from a vehicle controller unit (VCU), and operates the DC conversion circuit unit 100 to charge the low voltage battery LB . That is, when a charge command from the VCU is received during the off state, the corresponding charging operation is performed. In this case, as in the first mode, it is possible to charge the low voltage battery LB by outputting a voltage (eg, 14.2 ± 0.5V, etc.) higher than the voltage (eg, 12V) of the low voltage battery LB. have.

The third mode is operated when the ignition key is in an off state and an On Board Charger (OBC) is being charged, and operates the DC conversion circuit unit 100 to charge the low voltage battery LB. That is, if the OBC is being charged regardless of the charging command of the VCU during the off state, the corresponding charging operation is performed. In this case, as in the first mode, it is possible to charge the low voltage battery LB by outputting a voltage (eg, 14.2 ± 0.5V, etc.) higher than the voltage (eg, 12V) of the low voltage battery LB. have.

However, at least one of the first to third modes may be performed only when the voltage of the low voltage battery LB drops to less than a certain level (eg, less than 12V). That is, when the low-voltage battery LB is sufficiently charged, unnecessary waste of energy may be reduced by not performing the first to third modes, and shortening of the lifespan of the low-voltage battery LB may be prevented.

In particular, when the first to third modes are performed, the DC conversion circuit unit 100 outputs a voltage higher than the voltage of the low-voltage battery LB, so that the low-voltage battery LB can be charged within a shorter time.

In the detailed description of the present invention, although specific embodiments have been described, various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention is not limited to the described embodiments, and should be defined by the following claims and their equivalents.

100: DC conversion circuit unit 1 10: EMI filter unit
111, 152: capacitor 120: PWM unit
121, 122, 123, 124: switching element 125: PWM driver
130: transformer 131: primary coil
132: secondary coil 140: rectifying unit
141, 142: diode 150: smooth part
151: inductor 1000: low voltage DC converter
HB: High-voltage battery LB: Low-voltage battery

Claims (10)

A low voltage DC converter for converting electrical energy accumulated in a high voltage battery into a low voltage in a hybrid vehicle, an electric vehicle, or a hydrogen electric vehicle, comprising:
a direct current conversion circuit unit that switches direct current (DC) to make alternating current (AC) step-down, then rectifies to direct current (DC) and smoothes the voltage;
a communication unit for performing CAN communication with other devices in the vehicle; and
a control unit connected to the DC conversion circuit unit and the communication unit to control the operation of the DC conversion circuit unit and the communication unit;
The control unit is
When the ignition key (IGN Key) is in an on state, the low voltage DC converter according to claim 1, wherein the first mode of charging the low voltage battery is controlled by the operation of the DC conversion circuit unit.
According to claim 1,
The DC conversion circuit unit,
an EMI filter unit for filtering high voltage power;
a PWM unit for switching the output of the EMI filter unit into alternating current according to pulse width modulation (PWM);
a transformer for step-down the output of the PWM unit;
a rectifier for rectifying the output of the transformer; and
a smoothing unit for smoothing the output of the rectifying unit;
A low voltage DC converter comprising a.
3. The method of claim 2,
The low voltage DC converter according to claim 1, wherein the EMI filter unit includes a capacitor connected between the input terminals to which the high voltage power is input.
4. The method of claim 3,
The PWM unit,
a first switching element having one end connected to one end of the capacitor;
a second switching element having one end connected to one end of the capacitor;
a third switching element having one end connected to the other end of the first switching element and the other end connected to the other end of the capacitor;
a fourth switching element having one end connected to the other end of the second switching element and the other end connected to the other end of the capacitor; and
a PWM controller for controlling on/off of the first to fourth switching elements;
A low voltage DC converter comprising a.
5. The method of claim 4,
The transformer unit has a primary coil having one end connected between the first switching element and the third switching element and the other end connected between the second switching element and the fourth switching element, and is disposed to be spaced apart from the primary coil. Each includes a secondary coil,
The rectifying unit is a low voltage DC converter, characterized in that it comprises a diode connected to the secondary coil rectifying.
According to claim 1,
When the ignition key (IGN Key) is off, the control unit receives a signal from a vehicle controller unit (VCU) and controls the performance of the second mode of charging the low voltage battery by the operation of the DC conversion circuit unit Low voltage DC converter.
7. The method of claim 6,
The control unit controls the execution of the third mode of charging the low-voltage battery by the operation of the DC conversion circuit when the ignition key is in an off state and the On Board Charger (OBC) is being charged. low voltage dc converter.
8. The method of claim 7,
The first mode to the third mode is a low voltage DC converter, characterized in that it is performed when the voltage of the low voltage battery falls below a certain level.
9. The method of claim 8,
The DC converter circuit unit outputs a voltage higher than the voltage of the low voltage battery in the first mode to the third mode to charge the low voltage battery.
9. The method of claim 8,
The communication unit low voltage DC converter, characterized in that for receiving the on (on) / off (off) state signal of the ignition key (IGN Key).

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