KR20140081375A

KR20140081375A - Electronic Parking brake

Info

Publication number: KR20140081375A
Application number: KR1020120151049A
Authority: KR
Inventors: 임민식
Original assignee: 현대모비스 주식회사
Priority date: 2012-12-21
Filing date: 2012-12-21
Publication date: 2014-07-01

Abstract

An electronic parking brake device is provided. According to the present electronic parking brake apparatus, it is possible to provide an electronic parking brake apparatus including a motor driving unit implemented in a circuit form, so that the cost of each element is small, unlike the case of using the conventional ASIC, It is possible to implement the motor driving circuit and it is easy to access the circuit, and there is a lot of room for improving the electric characteristics such as electromagnetic waves, and it becomes easy to flexibly respond to the logic of driving the motor or fail-safe.

Description

Electronic parking brake device

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic parking brake apparatus, and more particularly, to an electronic parking brake apparatus in which a motor driving unit is implemented in a circuit form.

Most of the current parking brake systems have a key role in stabilizing the car by applying braking force when parking the vehicle by pressing the parking brake pedal by the driver (by foot) or by pulling the lever (by hand). However, the EPB (Electronic Parking Brake) system is a progressive control system that is designed to operate or release the parking brake automatically in conjunction with the manual operation mode of the driver and the HECU, engine ECU, and TCU by simple switch operation and to ensure braking stability in emergency situations. Parking brake system. Although the EPB system applied to enhance the convenience and safety of a vehicle has a high degree of freedom of installation on a vehicle, recently, the EPB system is integrated with a brake caliper to further enhance the mounting capability of the EPB.

In this way, the caliper-integrated type EPB mounts an actuator composed of a motor and a multi-stage gear box for amplifying the motor's power, on the caliper of both rear wheels, so that the braking force can be applied by restricting the brake disk by the electric power. These actuators are controlled via a wire bundle from an EPB ECU attached to a separate internal position in the vehicle and the user's willingness to apply the parking braking force is obtained from the operation of an EPB switch directly connected to the ECU.

Such an EPB drives a motor using a motor driving unit using a voltage input from a battery.

Specifically, the battery input unit receives the battery power of the vehicle. The P-channel FET is used as a reverse voltage prevention circuit for the power input from the battery. Specifically, if a conventional diode is used as a countermeasure against reverse connection in a motor PWM driving device, a back-EMF generated when the motor is driven by a PWM may be caused by a reverse voltage resistance of the diode.

The motor driving unit is composed of two ASICs (Application Specific Integrated Circuits). The PWM of the motor driving frequency inputted from the ECU (Electronic Control Unit) and the control signals are controlled by the ASIC through the ASIC. Such a control signal activates an actuator including a motor to generate a braking force on the caliper (or drum) to serve as a parking brake.

The conventional motor driving unit can have an advantage that it can be more easily configured and can be easily controlled by using an ASIC in the form of one IC chip. However, by using an ASIC, it can take a long time to find the cause of defects when the parts cost is high and defects occur, and internal circuit tuning can not be performed. Therefore, it is difficult to improve the electromagnetic wave characteristics and it is difficult to form a protection circuit.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a motor driving unit that drives a motor in forward or reverse direction using a PWM signal and a control signal transmitted from a pre- And an electronic parking brake device.

According to an aspect of the present invention, there is provided an electronic parking brake (EPB) apparatus for a vehicle, which includes a PWM (Pulse Width Modulation) signal input from an ECU (Electronic Control Unit) A pre-driver for transmitting the pre-driver to the motor driver; And a motor driver for driving the motor in a forward or reverse direction using the PWM signal and the control signal transmitted from the pre-driver, the motor driver being implemented in a circuit form.

The motor driving unit may include an H-bridge circuit unit for driving the motor in forward or reverse directions according to a control signal input through the pre-driver using four N-ch FETs (Field Effect Transistor) have.

The motor driving unit includes a transistor whose base end is connected to the pre-driver, an emitter connected to the N-ch FET of the H-bridge circuit part, and a collector end connected to battery power, And a bootstrap circuit portion for raising the voltage of the PWM signal.

The bootstrap circuit portion may further include a capacitor connected between the output of the H-bridge circuit portion and the collector terminal.

The motor driving unit may further include a charge pump unit connected to a collector terminal of the transistor of the bootstrap circuit unit to supply charge.

The motor driving unit may include an oscillator.

The motor driving unit may further include a resistance unit including a resistor connecting the gate terminal and the source terminal of the N-ch FET included in the H-bridge circuit unit.

The resistance unit may include a resistance having a resistance value higher than a critical resistance value corresponding to the limiting current of the charge pump unit.

According to various embodiments of the present invention, it is possible to provide an electronic parking brake apparatus including a motor driving unit implemented in a circuit form, so that the cost of each element is small, unlike the case of using the conventional ASIC, It is possible to implement the motor driving circuit and it is easy to access the circuit and there is a lot of room for improving the electric characteristics such as electromagnetic waves and it becomes easy to flexibly respond to the logic of driving the motor or fail-safe .

1 is a view showing a structure of an electronic parking brake (EPB) apparatus included in a vehicle according to an embodiment of the present invention;
FIG. 2 illustrates a detailed structure of an H-bridge circuit according to an embodiment of the present invention; FIG.
3 is a diagram illustrating a detailed structure of a bootstrap circuit according to an embodiment of the present invention.

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

1 is a diagram showing a structure of an electronic parking brake (EPB) apparatus included in a vehicle according to an embodiment of the present invention.

1, the electronic parking brake apparatus 100 includes an ECU (Electronic Control Unit) 110, a pre-driver 120, a motor driving unit 130, and a motor 140 do.

The ECU 110 controls the overall operation of the electronic parking brake device 100. Also, the ECU 110 can transmit and receive various signals to various parts of the vehicle through CAN (Controller Area Network) communication. The ECU 110 also transmits a pulse width modulation (PWM) signal and a control signal to the pre-driver 120 for the electronic parking brake apparatus 100.

The pre-driver 120 transmits a PWM (Pulse Width Modulation) signal and a control signal input from the ECU 110 to the motor driver 130.

The motor driving unit 130 drives the motor 140 in a forward or reverse direction using a PWM (Pulse Width Modulation) signal and a control signal transmitted from the pre-driver 120.

1, the motor driving unit 130 includes a charge pump unit 131, a boot strap circuit unit 133, a resistor unit 135, and an H-bridge circuit unit 137, .

The H-bridge circuit unit 137 is capable of ON / OFF control (PWM duty 100%) together with the PWM signal control, and is constituted by a circuit for protecting the components, and controls the motor 140 using the circuit .

Hereinafter, the detailed structure of the H-bridge circuit portion 137 will be described with reference to FIG. 2 is a diagram showing the detailed structure of the H-bridge circuit portion 137 according to an embodiment of the present invention.

2, the H-bridge circuit unit 137 includes a first N-ch FET (Field Effect Transistor) 210 and a second N-ch FET 220. The first N- The first N-ch FET 210 and the second N-ch FET 220 each include two N-ch FETs. 2, the H-bridge circuit unit 137 includes four N-ch FETs, but may include four N-ch BJTs (Bipolar Junction Transistors).

The H-bridge circuit unit 137 drives the motor 140 in a circuit system using a PWM signal. The H-bridge circuit unit 137 applies a PWM signal to the gate GATE of the FET to flow a current using a state change.

The H-bridge circuit part 137 has a small Rdson which affects the thermal characteristics of the N-ch FET in view of the performance, and the N-ch FET has a fast operation characteristic, so that the H-bridge circuit part 137 is preferred to realize a better performance part. However, since the N-ch FET is located on the high-side of the H-bridge circuit portion 137, a problem arises. When the high-side turns on, the source of the high-side (A position) is not GND, so it has the voltage level of the drain. At that moment, the FET is turned off to have a potential higher than the voltage of the gate (GATE) terminal, so that the current can not flow. Vbatt can drive the motor until the current flows to GND, but the current path is cut off. For the current to flow, the first N-ch FET 210, which is a high-side FET, must have a GATE voltage higher than the source voltage by at least 5 to 10 V or more.

Accordingly, the motor driving unit 130 according to the present embodiment includes the boot strap circuit unit 133. Transistors which bootstrap circuit 133 is connected to the base terminal pre-driver 120 is already teodan is connected to the N-ch FET (137) of the H- bridge circuit is connected to the collector stages, the battery power source (V _Battery) ( TR), and the voltage of the PWM signal input from the pre-driver 120 is increased.

The detailed circuit diagram of the bootstrap circuit section 133 is as shown in FIG. 3 is a diagram showing a detailed structure of the bootstrap circuit portion 133 according to an embodiment of the present invention.

3, the bootstrap circuit portion 133 has a base end connected to the pre-driver 120, an emitter connected to the N-ch FET 137 of the H-bridge circuit portion, and a collector end connected to the battery power source V _battery ), and a capacitor B connected between the output of the H-bridge circuit part 137 and the collector terminal.

When the PWM high signal is applied from the pre-driver 120, the emitter output of the transistor TR of the bootstrap circuit 133 becomes lower than the Vbatt voltage. Thus, the FET of the H-bridge circuit unit 137 is turned on, and a High signal is outputted to the output of the motor which is the output of the H-bridge circuit unit 137. The collector voltage of the transistor TR becomes Vbatt + the output signal voltage because the High signal of the output of the H-bridge circuit part 137 enters the collector terminal of the transistor TR through the capacitor B. Since the PWM signal output from the pre-driver 120 passes through the bootstrap circuit section 133 and the voltage of the PWM signal becomes higher, the N-ch FET of the H- The gate (GATE) has a higher voltage than the source (SOURCE). As described above, the motor driving unit 130 can turn on the FET of the H-bridge 137 without interruption by using the bootstrap circuit unit 133.

Meanwhile, the motor driving unit 130 controls the motor 140 through the PWM control. However, the motor driver 130 also performs ON-OFF control in a situation where a high output current is required. This ON-OFF control situation is a case where the PWM 100% duty control is performed.

The motor driving unit 130 can not use the 100% duty by adding only the bootstrap circuit unit 133 to the H-bridge circuit unit 137. [ This is because of the characteristics of the capacitor B that supplies the voltage to the bootstrap circuit 133. [ Since the capacitor only passes the alternating current but can not pass the direct current, when the 100% duty is used, the capacitor serves as a filter and the current can not flow. As a result, the high-side FET can not operate properly and can be damaged.

In order to cover such a disadvantage, the motor driving part 130 includes a charge pump part 131 of the transistor TR. The charge pump section 131 is connected to the collector terminal of the transistor TR of the bootstrap circuit section 133 to supply the charge so that the gate voltage of the FET of the H-bridge circuit section 137 is increased. As described above, the charge pump unit 131 allows the gate voltage to have a potential higher than the source voltage even when the bootstrap circuit unit 133 is used at 100% duty, thereby controlling the high-side FET There will be no problems. The charge pump section 131 may include a device having an oscillator therein.

On the other hand, there is a possibility that a problem may occur in the charge pump unit 131. If there is a problem in the ECU 110 or the pre-driver 120 that applies the PWM signal to the gate terminal and the gate terminal voltage state becomes a floating state, the charge pump unit 131 causes the H The FET of the bridge circuit part 137 can perform an abnormal operation such as being turned on unintentionally. As described above, when the FET of the H-bridge circuit unit 137 is turned on and turned on, an abnormal situation such as driving the motor may be generated. Therefore, a circuit for protecting the FET is required.

In order to prevent such a situation, the proposed circuit is a resistor 135 which connects the gate (GATE) terminal and the source (SOURCE) terminal. That is, the resistor section 135 includes a resistor connecting the gate terminal and the source terminal of the N-ch FET included in the H-bridge circuit section 137. The resistor 135 is a Safty resistor for preventing a malfunction by fully down-converting the voltage of the floating gate (GATE) to the source SOURCE.

The resistance value selection of the resistance portion 135 is also very important. The current capacity of the charge pump unit 131 is limited. In consideration of price and performance, the charge pump unit 131 uses a device having a very small current capacity. Actually, the current flowing through the gate (GATE) of the transistor TR of the bootstrap circuit portion 133 is very small (the FET controls the drain current by the voltage).

Therefore, the resistance value of the resistance included in the resistance portion 135 is used as a resistance value having a resistance value higher than the critical resistance value for causing the current of the limiting capacitance of the charge pump portion 131 to flow. Here, the critical resistance value represents a resistance value corresponding to the maximum limiting current that can flow to the charge pump section 131. [ If the resistance value is selected to be smaller than the critical resistance value, more current may flow than the limiting capacity of the charge pump section 131, which may damage the element.

The electronic parking brake apparatus 100 having such a configuration is provided with a charge pump section 131, a boot strap circuit section 133, a resistance section 135, and an H- The circuit portion 137 may be included in a circuit form so that the motor 140 can be controlled through PWM control. Accordingly, unlike the case of using the conventional ASIC, the electronic parking brake apparatus 100 can realize the motor driving unit 130 circuit with less cost because the cost of each device is small, and the circuit is easily accessible It is possible to improve the electric characteristics such as electromagnetic waves, and it becomes easy to flexibly respond to the logic for driving the motor or fail-safe.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.

100: Electronic parking brake device 110: ECU
120: pre-driver 130: motor driver
131: charge pump section 133: bootstrap circuit section
135: Resistor part 137: H-bridge circuit part
140:

Claims

In an electronic parking brake (EPB) apparatus of a vehicle,
A pre-driver for transmitting a PWM (Pulse Width Modulation) signal and a control signal input from an ECU (Electronic Control Unit) to a motor driving unit; And
And a motor driving unit for driving the motor in a forward or reverse direction using the PWM signal and the control signal transmitted from the pre-driver, the motor driving unit being implemented in a circuit form.

The method according to claim 1,
The motor drive unit includes:
And an H-bridge circuit unit for driving the motor in forward or reverse directions according to a control signal input through the pre-driver using four N-ch FETs (Field Effect Transistors) .

3. The method of claim 2,
The motor drive unit includes:
And a transistor whose base end is connected to the pre-driver and whose emitter terminal is connected to the N-ch FET of the H-bridge circuit part and whose collector terminal is connected to the battery power supply, and the voltage of the PWM signal input from the pre- Further comprising: a bootstrap circuit portion that is connected to the bootstrap circuit portion.

The method of claim 3,
The bootstrap circuit section includes:
And a capacitor connected between the output of the H-bridge circuit and the collector terminal.

The method of claim 3,
The motor drive unit includes:
And a charge pump unit connected to the collector of the transistor of the bootstrap circuit unit to supply charge.

6. The method of claim 5,
The motor drive unit includes:
And an oscillator.

6. The method of claim 5,
The motor drive unit includes:
Further comprising: a resistance portion including a resistor connecting the gate terminal and the source terminal of the N-ch FET included in the H-bridge circuit portion.

8. The method of claim 7,
Wherein the resistance portion comprises:
And a resistor having a resistance value higher than a critical resistance value corresponding to a limiting current of the charge pump section.