KR20190106181A - Methods for controlling EPS that cuts motor drive power when overcurrent occurs - Google Patents

Abstract

The present invention relates to an electric power steering (EPS) control device which cuts power applied to an H-bridge circuit when a fault occurs in the H-bridge circuit which drives a motor, and a method thereof. An embodiment of the present invention provides the EPS control device which comprises: one inverse voltage prevention MOSFET; an H-bridge circuit connected to the inverse voltage prevention MOSFET; a shunt resistance connected to the H-bridge circuit; an Op Amp connected to the shunt resistance; a switch transistor connected to the Op Amp; and a micro controller unit (MCU) controlling drive of the H-bridge circuit. When a double fault occurs in the H-bridge circuit, the EPS control device cuts the power applied to the H-bridge circuit by turning the inverse voltage prevention MOSFET off.

Description

{Methods for controlling EPS that cuts motor drive power when overcurrent occurs}

The present embodiment relates to an EPS control apparatus and a method thereof, and more particularly, to an EPS control apparatus and a method for interrupting power applied to the H-bridge circuit when a fault occurs in the H-bridge circuit for driving a motor. It is about.

Recently, the vehicle is equipped with various functions for the convenience of the driver, and various advanced detection sensors and electronic control devices are mounted to implement these functions.

On the other hand, the vehicle is provided with an electric power steering (EPS: Electronic Power Steering) to easily steer the steering wheel, the electric steering device assists the driver's steering power by using the rotational power of the steering motor.

In this case, an electronic relay may be installed inside the EPS control device to prevent malfunction of the EPS, prevent reverse voltage, and prevent burnout of the battery harness. If an electronic relay is used, two MOSFETs are used to cut off the power supply to the EPS, and a high side driving IC is required to control this. Therefore, a method for reducing the size of the MOSFETs and relays has been discussed to reduce the cost and size of the EPS control device.

The purpose of the present embodiment is to install only one MOSFET for preventing reverse voltage, and to cut off the power applied to the H-bridge circuit when an over current flows due to a fault in the H-bridge circuit driving the motor. The present invention provides an EPS control apparatus and method for preventing a fire from occurring in a harness or an electronic control unit (ECU).

One embodiment for solving the above-mentioned problems is an H-bridge circuit connected with one reverse voltage preventing MOSFET, an H-bridge circuit connected with a reverse voltage preventing MOSFET, a shunt resistor connected with the H-bridge circuit, and a shunt resistor connected with the H-bridge circuit. Micro-controller unit (MCU) that controls the operation of the op amp, the switch transistor connected to the op amp, and the H-bridge circuit, but when a double fault occurs in the H-bridge circuit, the reverse voltage protection MOSFET is turned off (Off) to provide an electric power steering (EPS) control device characterized in that the power applied to the H-bridge circuit is cut off.

In addition, an embodiment includes a fault detection step of detecting a fault occurrence of an H-bridge circuit, a determination step of determining a type and an error mode of the fault, and an H-bridge according to the type and error mode of the fault. A power off step of disconnecting power applied to the circuit, and when a double fault occurs in the H-bridge circuit, the reverse voltage prevention MOSFET is turned off to cut off the power applied to the H-bridge circuit. It provides an EPS control method characterized in that.

According to the present embodiment, even if only one reverse voltage preventing MOSFET is used and the high side IC is removed, the EPS control apparatus and method for cutting off the power applied to the H-bridge circuit when an overcurrent occurs due to a fault in the H-bridge circuit are described. Can provide. This can provide an EPS control device that can maintain safety while reducing cost and size.

1 is a view showing the configuration of a conventional EPS control device using two reverse voltage prevention MOSFETs.
Fig. 2 is a diagram showing the configuration of the EPS control device in this embodiment.
3 is a flowchart illustrating a procedure of shutting off power when a fault occurs in the present embodiment.

Hereinafter, some embodiments of the present invention will be described in detail through exemplary drawings. In adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same elements as much as possible even though they are shown in different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

In addition, in describing the component of this invention, terms, such as 1st, 2nd, A, B, (a), (b), can be used. These terms are only for distinguishing the components from other components, and the nature, order or order of the components are not limited by the terms. If a component is described as being "connected", "coupled" or "connected" to another component, that component may be directly connected to or connected to that other component, but there may be another configuration between each component. It is to be understood that the elements may be "connected", "coupled" or "connected".

1 is a view showing the configuration of a conventional EPS control device using two reverse voltage prevention MOSFETs.

Referring to FIG. 1, power input from a battery passes through two reverse voltage prevention MOSFETs 101 before entering the H-bridge circuit 110, which is a circuit for driving a motor. When the two reverse voltage protection MOSFETs 101 generate a fault in the H-bridge circuit 110 and an overcurrent occurs, the high side drive 102 controlling the two reverse voltage prevention MOSFETs 101 is overcurrent. By detecting the occurrence, the two reverse voltage prevention MOSFETs 101 are controlled so that power to the H-bridge circuit 110 is cut off.

The H-bridge circuit 110 is a circuit for driving the motor 111 of the EPS, and two MOSFETs 112 and 113 are connected to the high side of the motor 111 and two MOSFETs 114 and 115 to the low side. ) Is connected. MOSFET 112 and MOSFET 114, MOSFET 113 and MOSFET 115 are connected in series, and MOSFET 112 and 113 and MOSFET 114 and 115 are connected in parallel, respectively.

Problems that occur in the MOSFETs constituting the H-bridge circuit 110 are called faults. There are two types of faults: single faults and double faults.

Single fault means that a problem occurs only on one side of two MOSFETs 112 and 113 on the high side of the motor 111 or one of two MOSFETs 114 and 115 on the low side. In single fault, the error mode is open mode where open occurs in the MOSFET and short mode where short occurs. At this time, when a short occurs, a current larger than a normal value, that is, a current value in a state in which a fault does not occur, is generated in the conductive wire connected to the shorted MOSFET.

Double fault means that a problem occurs in both sides of two MOSFETs 112 and 113 on the high side of the motor 111 or two MOSFETs 114 and 115 on the low side. Double faults can occur when a short fault occurs in a MOSFET on one side in a single fault situation, when an overcurrent flows, and when a short occurs in the MOSFET on the other side before disconnecting power to the H-bridge circuit. have.

In the case of the aforementioned double fault, a very large overcurrent occurs in the H-bridge circuit, and a fire may occur inside the battery harness or the ECU (Electronic Control Unit) unless the power supply to the H-bridge circuit is quickly disconnected from the battery. Can be.

In addition, a shunt resistor 120 is connected to the H-bridge circuit 110. If the above-described single fault or double fault occurs in the H-bridge circuit 110, an overcurrent occurs in the shunt resistor 120. When an overcurrent flows through the shunt resistor 120, the voltage formed on the shunt resistor 120 increases, and when the voltage formed on the shunt resistor 120 is amplified through the op amp 130, an output portion of the op amp 130 is generated. An overvoltage may occur, and the MCU 140 may recognize the overvoltage to cut off power applied to the H-bridge circuit.

Fig. 2 is a diagram showing the configuration of the EPS control device in this embodiment.

Referring to FIG. 2, the power input from the battery passes through only one reverse voltage prevention MOSFET 101 before entering the H-bridge circuit 210, which is a circuit for driving the motor. Unlike the conventional EPS control device, there is no separate IC for driving high side to control the reverse voltage prevention MOSFET 101.

The H-bridge circuit 210 is a circuit for driving the motor 211 of EPS, and two MOSFETs 212 and 213 are connected to the high side of the motor 211 and two MOSFETs 214 and 215 to the low side. ) Is connected. MOSFETs 212 and 214, MOSFETs 213 and MOSFET 215 are connected in series, and MOSFETs 212 and 213 and MOSFETs 214 and 215 are connected in parallel, respectively. This is the same as the existing EPS control device.

A shunt resistor 220 is connected to the H-bridge circuit 210. If the above-described single fault or double fault occurs in the H-bridge circuit 210, overcurrent also occurs in the shunt resistor 220. When an overcurrent flows through the shunt resistor 220, the voltage formed on the shunt resistor 220 increases, and when the voltage formed on the shunt resistor 220 is amplified through the op amp 230, an output portion of the op amp 230 is applied. Overvoltage occurs.

When an overvoltage occurs in the output of the op amp 230, the MCU 240 connected to the output of the op amp 230 may recognize the overvoltage and cut off the power applied to the H-bridge circuit 210. .

In addition, an overvoltage generated at an output of the op amp 230 may be applied to the base of the switch transistor 250 connected to the op amp 230 to turn on the switch transistor 250.

Compared to the normal state where no fault occurs, a large voltage is output at the output of the Op Amp 230 when a single fault occurs, and a very large voltage is output at the output of the Op Amp 230 when a double fault occurs. . At this time, a passive element (resistance, diode) connected to the input of the switch transistor 250 such that the switch transistor is turned off when the steady state or a single fault occurs, and the switch transistor is turned on only when a double fault occurs. The characteristics of can be adjusted. In the normal state, it is not necessary to turn off the reverse voltage protection MOSFET 201, and in the case of a single fault, since the overcurrent protection control is performed by the MCU 240, it is also necessary to forcibly turn off the reverse voltage protection MOSFET 201. Because there is not.

If the switch transistor 250 is turned on, the gate voltage applied to the one reverse voltage preventing MOSFET 201 becomes greater than or equal to a preset threshold gate voltage, and thus the reverse voltage preventing MOSFET 201 is turned off. . When the reverse voltage prevention MOSFET 201 is turned off, the over-current no longer flows to the H-bridge circuit 210 because the power supplied from the battery to the H-bridge circuit 210 is cut off.

In such a double fault state, instead of allowing the MCU 240 to control overcurrent protection by software, it is possible to quickly cut off the power supplied from the battery to the H-bridge circuit 210 by using a device such as a transistor, a diode, and a resistor. This prevents the possibility of a fire that can be caused by a very large overcurrent when a double fault occurs.

3 is a flowchart illustrating a procedure of shutting off power when a fault occurs in the present embodiment.

Hereinafter, an example of executing this procedure by the EPS control apparatus described with reference to FIG. 2 will be described.

First, the EPS control apparatus may detect a fault occurrence of the H-bridge circuit 210 that drives the motor (S310). As described above, when the fault occurs, since the magnitude of the current flowing through the H-bridge circuit 210 is larger than the magnitude of the current in the normal state in which the fault does not occur, the fault may be detected based on this.

Subsequently, the EPS control apparatus may determine the type of the fault and the error mode. As described above, there are single faults and double faults, and error modes include open mode and short mode. The method for shutting off the power applied to the H-bridge circuit varies depending on the type of fault and the error mode.

As described above, since a double fault occurs in a special case in which a short occurs in a MOSFET on the other side after a single fault occurs, it is determined that a single fault has occurred.

First, in the EPS control apparatus, it is determined whether the error mode is an open mode which is an error caused by the opening of the MOSFET (S320). If the error occurred due to the open (S320-Y), the MCU 240 of the EPS control device recognizes the single fault / open mode, and may cut off the power applied to the H-bridge circuit 210 (S370). .

If the error mode is not an error caused by the opening of the MOSFET but a short mode caused by a short (S320-N), it is necessary to determine whether the fault type is a single fault or a double fault. As described above, when a double fault occurs, a larger overcurrent flows in the motor 211 than in the case of a single fault, so whether or not the magnitude of the current applied to the motor 211 is equal to or less than a threshold current value corresponding to the double fault. The fault type can be distinguished accordingly.

If the motor current applied to the motor is below the threshold current (S330-Y), the EPS control device determines that the fault type is a single fault, and the MCU 240 of the EPS control device recognizes the single fault / open mode, The power applied to the H-bridge circuit 210 may be cut off (S370).

If the motor current applied to the motor exceeds the threshold current (S330-N), the EPS control device may determine that the fault type is a double fault. As described above with reference to FIG. 2, when a double fault occurs, the voltage applied to the shunt resistor 220 is applied to the input side of the op amp 230, and the switch transistor 250 is driven by the overvoltage amplified through the op amp 230. It is On (S340). In operation S350, the switch transistor 250 is turned on so that the gate voltage applied to the reverse voltage prevention MOSFET 201 becomes greater than or equal to a predetermined threshold gate voltage (S350). Since the reverse voltage prevention MOSFET 201 is off, power applied from the battery to the H-bridge circuit is cut off (S360).

The standard contents or standard documents mentioned in the above embodiments are omitted to simplify the description of the specification and form a part of the present specification. Therefore, the addition of the contents of the standard and part of the standard documents to the specification or the description in the claims should be construed as falling within the scope of the present invention.

The above description is merely illustrative of the technical spirit of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. 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 interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

Claims (8)

1 reverse voltage protection MOSFET;
An H-bridge circuit connected to the reverse voltage prevention MOSFET;
A shunt resistor connected to the H-bridge circuit;
Op Amp connected to the shunt resistor;
A switch transistor connected to the op amp; And
Including a MCU (Micro Controller Unit) for controlling the driving of the H-bridge circuit,
When a double fault occurs in the H-bridge circuit, the reverse voltage prevention MOSFET is turned off to cut off power applied to the H-bridge circuit. Device. The method of claim 1,
The voltage formed on the shunt resistor is applied to the input side of the Op Amp,
A voltage on the output side of the Op Amp is applied to the base of the switch transistor,
And when the switch transistor is turned on, the gate voltage applied to the reverse voltage prevention MOSFET becomes higher than or equal to a preset threshold gate voltage so that the reverse voltage prevention MOSFET is turned off. The method of claim 1,
The MCU,
And when a single fault occurs in the H-bridge circuit and an error mode is an open mode, power applied to the H-bridge circuit is cut off. The method of claim 1,
The MCU,
And when the single fault occurs in the H-bridge circuit and the error mode is a short mode, the power applied to the H-bridge circuit is cut off. A fault detection step of detecting a fault occurrence of the H-bridge circuit;
Determining a type of the fault and an error mode; And
A power off step of shutting off power applied to the H-bridge circuit according to the type of fault and the error mode;
And when a double fault occurs in the H-bridge circuit, a reverse voltage prevention MOSFET is turned off and the power applied to the H-bridge circuit is cut off. The method of claim 5,
When a double fault occurs in the H-bridge circuit, a voltage formed on the shunt resistor is applied to the input side of the op amp,
A voltage on the output side of the Op Amp is applied to the base of the switch transistor,
And when the switch transistor is on, the gate voltage applied to the reverse voltage prevention MOSFET becomes equal to or greater than a predetermined threshold gate voltage so that the reverse voltage prevention MOSFET is turned off. The method of claim 5,
The power off step,
And when the single fault occurs in the H-bridge circuit and the error mode is the open mode, the MCU cuts off the power applied to the H-bridge circuit. The method of claim 5,
The power off step,
And when the single fault occurs in the H-bridge circuit and the error mode is a short mode, the MCU cuts off the power applied to the H-bridge circuit.

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