KR101459791B1 - Precharger of hybrid electric vehicle - Google Patents

Abstract

The present invention relates to a precharger of a hybrid vehicle, and more particularly, to a hybrid vehicle which is connected in parallel with a main relay between a high-voltage battery and other systems to prevent damage to an electric load due to a surge current, Quot ;. More particularly, the present invention relates to a precharger of a hybrid vehicle which uses a semiconductor switch instead of a conventional mechanical precharge relay and at the same time eliminates a large amount of wattage resistance (existing precharge resistance) and uses a small- . According to the precharger of the present invention, since a relatively inexpensive semiconductor switch is used in place of a mechanical relay, it is possible to reduce the cost, improve the life span semi-permanently, and eliminate noises generated during the conventional relay operation It becomes. In addition, since the semiconductor switch and the feedback resistor of a small capacity are used, the total volume of the precharger can be reduced and the current flowing through the precharger is controlled by the resistance feedback loop, thereby improving the quality of the precharging current.

Hybrid vehicle, free charger, relay, resistance, semiconductor switch, MOSFET, feedback

Description

[0001] The present invention relates to a precharger of a hybrid electric vehicle,

The present invention relates to a precharger of a hybrid vehicle, and more particularly, to a hybrid vehicle which is connected in parallel with a main relay between a high-voltage battery and other systems to prevent damage to an electric load due to a surge current, Quot ;.

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

Such a hybrid vehicle is a future type vehicle that can improve fuel economy and reduce exhaust gas by adopting an electric motor as an auxiliary power source as well as an engine. In response to the request of the times, it is necessary to develop fuel economy and environmentally friendly products, .

Hybrid vehicles can form various structures using engines and electric motors (driving motors) as power sources. Because they can use the mechanical energy of the engine and the electric energy of the battery at the same time, they can be widely used for passenger cars .

Particularly, since the optimum operating region of the engine and the electric motor is used, not only the fuel efficiency of the entire drive system is improved, but also energy can be recovered by the electric motor at the time of braking.

On the other hand, a typical battery system in a hybrid vehicle includes a high-voltage relay unit including a battery unit (high-voltage battery) composed of a plurality of batteries, and a relay for connecting the battery line.

Here, the purpose of using the high-voltage relay unit is to secure electrical insulation between the energy storage medium and the other system, and when the vehicle is in operation, the relay is short-circuited to supply power, but the key off or maintenance In case of emergency, the relay is opened to secure the electrical stability.

In addition, it prevents the occurrence of major secondary accidents such as electric shock and fire caused by high voltage in the event of a primary accident, and also functions to cut off the dark current of the battery.

1 is a view showing a battery, a relay, and the like in a hybrid vehicle. In FIG. 1, a hybrid battery includes a high voltage battery 10, a main relay 20, a precharge relay 31, a precharge resistor 32, a capacitor 40, an electric load (inverter, LDC, etc.) 50, and the like.

As shown in the drawing, the precharge relay 31 and the precharge resistor 32 are connected in series to constitute a precharger 30. The precharger 30 is connected between the high voltage battery 10 and the capacitor DC link stage To the main relay 20 in parallel. The capacitor 40 is a component that functions as a buffer after being properly charged and discharged between the high voltage battery 10 and the electric load 50 in order to cope with sudden power fluctuation of the electric load 50.

In the hybrid vehicle, the DC-link voltage is conducted to the motor by using the above-described precharger 30 to prevent damage to the inverter due to the surge current. Particularly, since the precharger 30 is connected to the main relay 20, The surge current generated at the time of the on state of the relay is cut off, thereby preventing the component damage and the relay fusion which may be caused by the surge current.

2, when the precharge relay 31 is first turned on, the peak current due to the resistance is limited and the capacitor 40 is charged. After that, the main relay 20 is turned on and the precharge relay 31 are turned off to start charging and discharging.

Meanwhile, since the precharge relay 31 and the watt resistor (precharge resistor) 32, which are mechanical relays, are used to constitute the precharger 30 of the hybrid vehicle in the related art, there is a problem that noise is seriously generated during operation. In addition, since the relays are mechanical, they do not have a long life, and a large amount of wattage resistance is used, which causes a disadvantage that the total volume becomes very large.

Therefore, there is a need to solve the problem of noise and lifetime of the mechanical relay and the problem of the volume of the watt resistance in the precharger of the conventional hybrid vehicle.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made in order to solve the above-mentioned problems, and it is an object of the present invention to provide a hybrid system capable of reducing the total volume by eliminating a large amount of wattage resistance, It is an object of the present invention to provide a precharger of a vehicle.

In order to achieve the above object, the present invention provides a precharger for a hybrid vehicle, which is connected in parallel with a main relay to prevent damage to an electric load due to a surge current and fusion of a main relay, A feedback resistor connected in series to an output terminal of the semiconductor switch for feedback control of a gate voltage and an output current to limit an output current, And a voltage source for applying a driving voltage to the gate of the semiconductor switch.

According to another aspect of the present invention, there is provided a precharger for a hybrid vehicle, which is connected in parallel with a main relay to prevent damage to an electric load due to a surge current and fusion of a main relay, A semiconductor switch connected in parallel to the main relay and controlled on and off, a voltage source for providing a driving voltage of the semiconductor switch, and a driving circuit for controlling the driving voltage of the voltage source, And a control unit.

Thus, according to the precharger of the present invention, since the semiconductor relay is replaced by a relatively inexpensive semiconductor switch, the cost can be reduced, the lifetime can be semi-permanently improved, and the noise generated during the conventional relay operation can be eliminated Noiseless implementation is possible. Additional cost to reduce noise can be reduced, which can save a lot of money.

In addition, the current control method can reduce the total volume of the precharger by using a small-capacity (less than 1 W) feedback resistor to eliminate the existing wattage resistor (using a feedback resistor to eliminate bulky, large- , The current flowing through the precharger is controlled by the resistance feedback loop, thereby improving the quality of the precharging current.

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

FIG. 3 is a circuit diagram showing the configuration of a precharger according to an embodiment of the present invention.

The present invention relates to a method of connecting a high-voltage battery 10 and other systems in parallel with a main relay 20 to damage a load (such as an inverter) 50 due to a surge current, The present invention relates to a precharger 30 'of a hybrid vehicle in which a semiconductor switch 33 is used instead of a conventional mechanical relay as a precharge relay and a large amount of wattage resistance Charge resistance) and to use a small-capacity feedback resistor 34 for current control.

3, the high voltage battery 10 and the main relay 20, which are basic components of the battery system in the hybrid vehicle, the semiconductor switch 33 constituting the precharger 30 ', and the feedback resistor 34 A voltage source 35, a capacitor 40, an electric load (inverter, LDC, etc.) 50, and the like.

3, the precharger 30 'according to an embodiment of the present invention is connected in parallel with the main relay 20 between the high voltage battery 10 and the capacitor DC link stage, A feedback resistor 34 connected in series to the output terminal of the semiconductor switch 33 for limiting the output current so that feedback control of the gate voltage and the output current is performed, And a voltage source 35 for applying a driving voltage to the gates of the transistors 33 and 33.

The precharger 30 'of the present invention uses the above-described feedback resistor 34 to adjust the output current value. By using the feedback resistor 34, the current I flowing to the precharger is adjusted by the feedback loop. .

It is preferable to use a metal-oxide-semiconductor field-effect transistor (MOSFET) as the semiconductor switch 33 employed as the precharge relay in the precharger 30 'of the present invention.

Also, in the precharger 30 'of the present invention, the feedback resistor 34 is provided for current control, and it is possible to use a small capacity (for example, 1 W or less) resistance.

A view for explaining the attached Figure 4 the operation mechanism, in the pre-charger of the present invention, pre-charger (30 ') to limit the current (I) flowing in the voltage between the semiconductor element (33), GE (V _GS Is controlled by negative feedback by the feedback resistor 34.

5A and 5B show the relationship between the GE voltage and the current flowing in the MOSFET as the semiconductor device (MOSFET current according to the gate voltage). When the current flows, the voltage V _Rsf is applied to the feedback resistor 34, The inter-GE voltage (V _GS ) falls and the current (I) is limited to a constant value. At this time, since a large voltage is not applied to the feedback resistor 34, a small amount of resistance can be used because the calorific value is small (for example, the calorific value is less than 2.5% compared to the conventional large capacity pre-charging resistor).

However, in the conventional precharger, the heat generated in the precharge circuit 30 'of the present invention generated in a large capacity precharge resistor (reference numeral 32 in FIG. 1) is generated in the semiconductor switch 33. In this case, Since the semiconductor switch is attached to the heat sink of the inverter or LDC, there is no additional cost for heat dissipation.

Referring again to FIG. 4, the current I flowing to the precharger 30 'can be expressed by the following equation (1).

(1)

(One)

As a result, when the inter-GE voltage V _GS of the semiconductor relay 33 is controlled to negative feedback by the feedback resistor 34, the feedback loop will be described. When the V _GS is lowered due to the characteristic of the semiconductor switch 33, the lower and, lowers the voltage V across _Rsf between the current I decreases, both ends of the feedback resistor, and the voltage V of the feedback resistance _Rsf is low when V _GS increases.

When V _GS rises, I rises. When I rises, the voltage V _Rsf of the feedback resistor rises. When V _Rsf rises, V _GS rises. As a result, this feedback loop causes the current flowing to the precharger 30 ' The current I is regulated.

Meanwhile, an example of a rated design of a semiconductor switch and a resistor when the precharge relay is replaced with a semiconductor switch in the precharge relay and the precharge resistance shown in FIG. 1 will be described. For the sake of convenience of calculation, the maximum voltage of the battery is assumed to be 200V and designed in the same manner as the mechanical relay. That is, in the precharger configuration of the prior art shown in FIG. 1, only the mechanical relay (precharge relay) portion can be designed to be replaced with a semiconductor switch (see the following expression, see FIG. 1).

First, the current and voltage can be calculated as follows.

<Current calculation>

Where V is the battery voltage, R is the resistance, I is the current, L is the inductance, and C is the capacitance of the capacitor.

At this time, since there is almost no inductance, assuming L = 0,

(2)

(2)

Here, Vb represents the battery voltage.

<Resistance Voltage Calculation>

(3)

(3)

<Calculation of capacitor voltage>

(4)

(4)

<Power and energy transfer to each device>

- Power charged to capacitor

- energy charged by the capacitor

(5)

(5)

- Power consumed in resistance

(6)

(6)

- energy consumed in resistance

(7)

(7)

Next, as an example, the rated design of the semiconductor relay and the resistor is as follows.

- maximum current: 5A by the formula (2) (see FIG. 1).

- Maximum voltage: 250V or more depending on the maximum battery voltage.

- Instantaneous maximum power: Approximately 1000W (assuming maximum battery voltage = 200V) according to equation (6).

- Average power:

ㆍ Assumption: The worst condition is the condition to keep charging every 2 seconds (Typical shortest charge-discharge cycle is 3-5 seconds).

(10J / 2sec) since the energy is 10J according to the equation (7).

- Power distribution according to the resistance value of the semiconductor switch (Rdson) and the external resistance (pre-charge resistance) (Rs)

ㆍ Resistance value of external resistor: 40Ω (noise considering time constant)

ㆍ The resistance value of semiconductor switch is designed to be 10 times smaller than the resistance value of external resistor.

ㆍ External power consumption: 5W

3 and 4, in which the semiconductor switch and the feedback resistor are used, the current I flowing to the precharger 30 'can be expressed as Equation (1) = 5A, the resistance value R _SF of the feedback resistor 34 is calculated by substituting Vcc = 15V, I = 5A, V _GS = 5V (the current value increases as the V _GS value is smaller) It can be designed as follows.

In FIG. 5, the gate voltage (V _GS ) which limits the maximum current to 5 A is 5 to 5.5 V.

FIG. 6 is a view for explaining a rated design of the precharger configuration shown in FIG. 3 for controlling an output current using a feedback resistor. Referring to FIG.

Here, V _FET represents the voltage across the semiconductor switch 33, V _C represents the voltage of the capacitor 40, and R _SF represents the resistance value of the feedback resistor 34, respectively.

If this case, V _b = a _{200V, I = 5A, R SF} = 2Ω, C = 500㎌,

.

FIG. 7 is a diagram illustrating a semiconductor switch voltage (MOSFET voltage), a feedback resistance voltage (R _SF ), and the like in the precharger configuration according to an embodiment of the present invention.

8 is a circuit diagram showing a configuration of a precharger according to another embodiment of the present invention. In the illustrated precharger configuration, instead of using a feedback resistor to adjust an output current value by adjusting a gate voltage, And the gate voltage is adjusted by the driving circuit.

That is, the illustrated precharger 30 "includes a semiconductor switch 33 connected in parallel with the main relay 20 between the high voltage battery 10 and the capacitor DC link stage, A voltage source 35 for providing a driving voltage of the switch 33 and a driving circuit 36 for adjusting the driving voltage of the voltage source 35 and applying the adjusted driving voltage to the gate voltage of the semiconductor switch.

Here, as the semiconductor switch 33, it is preferable to use a MOSFET.

The driving circuit unit 36 is a component that receives a driving voltage of the voltage source 35 and adjusts a gate voltage applied to the semiconductor switch. The driving circuit unit 36 includes an IC As shown in FIG. The driver circuit portion 36 may be configured to include a zener diode, and may be configured to use a zener diode, for example, to maintain the gate voltage at a threshold voltage when a current of 5 A flows.

As described above, the precharger using the semiconductor switch has been described. According to the precharger of the present invention, since the semiconductor relay using the relatively inexpensive semiconductor switch is used instead of the mechanical relay, the cost can be reduced and the life span can be improved semi-permanently So that the noise generated during the conventional relay operation can be eliminated and noise-free implementation can be realized. Additional cost to reduce noise can be reduced, which can save a lot of money.

In addition, the current control method can reduce the total volume of the precharger by using a small-capacity (less than 1 W) feedback resistor to eliminate the existing wattage resistor (using a feedback resistor to eliminate bulky, large- , The current flowing through the precharger is controlled by the resistance feedback loop, thereby improving the quality of the precharging current.

1 is a view showing a battery, a main relay and a conventional precharge relay in a hybrid vehicle,

FIG. 2 is a diagram showing an operation sequence of a conventional pre-charge relay and a main relay,

3 is a circuit diagram showing the configuration of a precharger according to an embodiment of the present invention,

4 is a view for explaining an operation mechanism of a precharger according to an embodiment of the present invention;

5 is a diagram showing a relationship between a voltage between G and E of a MOSFET as a semiconductor device and a current flowing therethrough,

6 is a view for explaining a rated design of a precharger arrangement according to an embodiment of the present invention;

FIG. 7 is a diagram illustrating an operation sequence of a semiconductor switch and a main relay, a semiconductor switch voltage, a feedback resistor voltage, and the like in a precharger configuration according to an embodiment of the present invention;

8 is a circuit diagram showing a configuration of a precharger according to another embodiment of the present invention;

Description of the Related Art

10: High voltage battery 20: Main relay

30 ', 30 ": precharger 33: semiconductor switch

34: feedback resistor 35: voltage source

36: drive circuit section 40: capacitor

50: Electric load

Claims (2)

In the precharger 30 'of the hybrid vehicle, which is connected in parallel with the main relay 20 to prevent damage to the electric load 50 and fusion of the main relay 20 due to the surge current, A semiconductor switch 33 connected in parallel with the main relay 20 between the high voltage battery 10 and the capacitor DC link end and controlled on and off; And a voltage source 35 for applying a driving voltage to the gate of the semiconductor switch 33. The feedback resistor 34 is connected to the gate of the semiconductor switch 33 to feedback control the gate voltage and the output current, Free charger of vehicle. In the precharger 33 "of the hybrid vehicle which is connected in parallel with the main relay 20 to prevent damage to the electric load 50 and fusion of the main relay 20 due to the surge current, A semiconductor switch 33 connected in parallel with the main relay 20 between the high voltage battery 10 and the capacitor DC link end and controlled on and off, a voltage source 35 providing a driving voltage of the semiconductor switch 33, And a drive circuit (36) for adjusting the drive voltage of the voltage source (35) and applying the adjusted gate voltage to the semiconductor switch (33).

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