KR102001079B1 - Apparatus for determining switch error in bi-directional converter and method thereof - Google Patents

Abstract

The present invention relates to an apparatus and a method for determining a switch failure of a bidirectional converter, comprising: a main battery and a sub battery each having a low voltage power source; a first switch connected to a positive terminal and a terminal of the main battery; A second switch connected between the negative terminal of the battery, an inductor connected to a connection node of the first and second switches, a third switch connected between the other terminal of the inductor and the positive terminal of the sub battery, A bidirectional converter including a fourth switch connected between the connection node of the three switches and the negative terminal of the sub battery, and a current sensor for sensing the current flowing through the inductor, and a failure determination target determined by any one of the first to fourth switches And a control unit for determining whether or not the switch is faulty, Which is connected to the failure determination target switch so that a loop connecting the failure determination target switch and the failure determination target switch is formed, And judges whether or not a fault has occurred.

Description

[0001] APPARATUS FOR DETERMINING SWITCH ERROR IN BI-DIRECTIONAL CONVERTER AND METHOD THEREOF [0002]

The present invention relates to an apparatus and method for determining a switch failure in a bidirectional converter, and more particularly, to an apparatus and method for determining a switch failure in a bidirectional converter that determines whether a switch included in a bidirectional converter is malfunctioning.

Recently, the demand for the development of a bidirectional low-voltage DC-DC converter in an application field of renewable energy, an environment-friendly automobile, an uninterruptible power supply (UPS) system, and an energy storage device is increasing. These bidirectional low-voltage converters are used in a multi-phase structure to accommodate high capacity, ensure quick response of power conversion, and share current to improve efficiency.

As the bidirectional low-voltage converter is developed as a multi-phase structure, the number of switches included in the power conversion system increases and the probability of failure of the switch increases. Generally, when a switch fails in a bidirectional low-voltage converter, the switch is short-circuited. When another switch is turned on with the fault switch shorted, the bidirectional low-voltage converter may form a closed loop with the power supply, and the converter may be damaged if the short-circuit current continues to flow in the closed loop Problems can arise.

Since the current and voltage generated by such a short-circuit current vary greatly instantaneously, there is a problem in that an expensive sensor capable of precisely detecting the current and the voltage is required in order to determine a switch failure. In addition, There is a problem that complex algorithms are required to determine a failure for a plurality of switches included in the low voltage converter.

The background art of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2011-0072013 (published on June 29, 2011).

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 improve the stability of a converter operation by checking a failure of a switch before a bidirectional converter operates, The present invention provides an apparatus and method for judging a switch failure of a bidirectional converter for improving the ease of judging a switch failure by removing a sensor or a complicated algorithm.

An apparatus for determining a switch failure of a bidirectional converter according to an aspect of the present invention includes: a main battery and a sub battery each having a low voltage power source; a first switch connected to a positive terminal and a terminal of the main battery; A second switch connected between a negative terminal of the main battery and an inductor to which a terminal is connected to a connection node of the first and second switches, a second terminal connected between the other terminal of the inductor and the positive terminal of the sub battery, 3 converter, a bidirectional converter including a fourth switch connected between a connection node of the inductor and the third switch and a negative terminal of the sub battery, and a current sensor for sensing a current flowing in the inductor, And a fourth switch for determining whether or not a failure determination target switch is determined to be faulty, The fisher unit turns on any one of the switches other than the failure determination target switch so that a loop connecting the battery of the main battery and the sub battery and the failure determination target switch is formed, And determining whether or not the failure determination object switch is faulty based on an inrush current generated by forming a closed loop.

In the present invention, the control unit may initialize the first to fourth switches by turning off the switches before turning on any one of the switches other than the fault determination target switch.

In the present invention, the control unit controls one of the switches other than the fault determination target switch by PWM (Pulse Width Modulation) control to turn on the switch.

In the present invention, if the failure determination target switch is one of the first and second switches, the control unit turns on the third switch, and if the inrush current is sensed by the current sensor, Is judged to be a failure of the vehicle.

In the present invention, the failure determination object switch is any one of the third and fourth switches, and the control unit turns on the first switch. When the inrush current is sensed by the current sensor, Is judged to be a failure of the vehicle.

In the present invention, the control unit further determines whether or not each switch included in the multi-phase converter in which a plurality of the bidirectional converters are connected in parallel is failed, and determines whether the switch included in each bidirectional converter constituting the multi- To the respective bidirectional converters, and further determines whether each of the switches included in the multiphase converter is faulty.

A method of determining a switch failure of a bidirectional converter according to an aspect of the present invention is characterized in that the control unit includes a step of initializing the first to fourth switches by turning off the first and second switches, Turning on any one of the switches other than the fault determination object switch so that a loop connecting the switch to be fault-diagnosed is formed, wherein the fault determination object switch is any one of the first to fourth switches, And determining whether the failure determination target switch is faulty based on an inrush current generated when a closed loop is formed due to the switch being turned on.

The controller may further determine whether each switch included in the multi-phase converter in which a plurality of the bidirectional converters are connected in parallel is faulty or not, and determines whether the switch included in each bidirectional converter constituting the multi- Further comprising determining sequentially for each of the bidirectional converters and determining whether each of the switches included in the multi-phase converter is faulty.

According to one aspect of the present invention, the present invention can reduce costs and simplify a power conversion system by eliminating expensive sensors or complex algorithms for determining a switch failure of a bidirectional converter, The stability of the power conversion system can be improved.

1 is a circuit diagram for explaining an apparatus for determining a switch failure in a bidirectional converter according to an embodiment of the present invention.
FIG. 2 is an exemplary view for explaining a closed loop formed by a switch failure in an apparatus for determining a switch fault in a bidirectional converter according to an embodiment of the present invention. Referring to FIG.
3 is a diagram illustrating an example of a bi-directional converter implemented by a multiphase converter in an apparatus for determining a switch failure of a bidirectional converter according to an embodiment of the present invention.
4 is a flowchart illustrating a method of determining a switch failure in a bidirectional converter according to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an apparatus and method for determining a switch failure of a bidirectional converter according to the present invention will be described with reference to the accompanying drawings. In this process, the thicknesses of the lines and the sizes of the components shown in the drawings may be exaggerated for clarity and convenience of explanation. In addition, the terms described below are defined in consideration of the functions of the present invention, which may vary depending on the intention or custom of the user, the operator. Therefore, definitions of these terms should be made based on the contents throughout this specification.

FIG. 1 is a circuit diagram for explaining an apparatus for determining a switch fault in a bidirectional converter according to an exemplary embodiment of the present invention. FIG. 2 is a block diagram of a switch failure detector in a bidirectional converter according to an exemplary embodiment of the present invention. 3 is a diagram illustrating an example of a bidirectional converter implemented with a multiphase converter in an apparatus for determining a switch fault in a bidirectional converter according to an embodiment of the present invention.

Referring to FIG. 1, an apparatus for determining a switch failure of a bidirectional converter according to an embodiment of the present invention includes a main battery MB and a sub battery SB, a main battery MB, and a main battery MB having a low voltage power source A bidirectional converter BC located between the sub batteries SB to control the power conversion flow and a control unit for determining whether the first to fourth switches SW1 to SW4 provided in the bidirectional converter BC are faulty ECU).

The bidirectional converter BC includes first to fourth switches SW1 to SW4, an inductor L and a current sensor (not shown) ISEN).

The first switch SW1 is connected to the positive terminal (+ terminal) of the main battery MB and one terminal thereof. The second switch SW2 is connected between the other terminal of the first switch SW1 and the negative terminal (- terminal) of the main battery MB. The inductor L is connected to a connection node between the first switch SW1 and the second switch SW2 and one terminal thereof. The third switch SW3 is connected between the other terminal of the inductor L and the positive terminal (+ terminal) of the sub battery SB. The fourth switch SW4 is connected between the connection node of the inductor L and the third switch SW3 and the negative terminal (- terminal) of the sub battery SB. The current sensor ISEN is configured to sense the current flowing in the inductor L. The first to fourth switches SW1 to SW4 may be configured by FETs (Field Effect Transistors), but the present invention is not limited thereto and various types of switches may be employed.

On the other hand, a multi-phase converter to be described later is a structure in which a plurality of bidirectional converters BC are connected in parallel, and each bidirectional converter BC constitutes one phase for successively performing power conversion in the multi-phase converter.

The current sensor ISEN senses the current flowing in the inductor L and can transmit the sensed current to the control unit ECU. In this embodiment, the current sensor ISEN senses an inrush current generated by forming a closed loop due to a failure switch and transmits the sensed inrush current to the control unit (ECU). Accordingly, the control unit ECU determines whether or not an inrush current is generated and determines the failure of the corresponding switch. A detailed description will be given later.

Based on the above-described circuit configuration, the control unit ECU can determine whether or not a failure determination target switch determined by any one of the first to fourth switches SW1 to SW4 is faulty.

Specifically, the control unit ECU turns on any one of the switches other than the failure determination target switch so that a loop connecting the battery of the main battery MB and the sub battery SB to the failure determination target switch is formed, It is possible to determine whether or not the switch to be fault-diagnosed is on the basis of the inrush current generated by the closed loop due to the switch being turned on.

That is, since the failure switch short-circuits both ends of the switch, the control unit ECU forms a loop connecting the switches to be subjected to battery-fault determination by turning on any one of the switches other than the switch to be fault- , It can be determined that a closed loop is formed due to the short-circuit of the fault switch, so that the control unit ECU can determine that the fault-determining switch is faulty.

On the other hand, the control unit may apply the control signals SIG <1: 4> to the first to fourth switches SW1 to SW4 to turn on / off the respective switches.

The control unit ECU can initialize and initialize the first to fourth switches SW1 to SW4 before judging whether or not the switch is faulty, and then determine whether the switch to be fault-diagnosed is faulty or not. In other words, as will be described later, the control unit ECU determines whether a closed loop is formed by turning on any one of the switches other than the fault target switch. Therefore, after all the switches are turned off and initialized, It is possible to clearly determine whether or not an inrush current is generated due to the formation of a closed loop by turning on only the corresponding switch, thereby determining whether or not the switch to be fault-detected is faulty.

Table 1 below shows a closed loop formed according to a failure judgment large-capacity switch (failure), a turn-on switch (PWM-after-mentioned) necessary for forming a closed loop, and a turn-on switch.

Item The first switch
(SW1) The second switch
(SW2) The third switch
(SW3) The fourth switch
(SW4) Closed loop One broken OFF PWM OFF ① 2 OFF broken PWM OFF ② 3 PWM OFF broken OFF ① 4 PWM OFF OFF broken ③

A process of determining whether the first to fourth switches SW1 to SW4 are failed will be described in detail with reference to Table 1. First, when the switch to be tested for failure is the first switch SW1, The control unit ECU turns on the third switch SW3 and can determine that the first switch SW1 has failed if the inrush current is sensed by the current sensor ISEN.

That is, when the first switch SW1 is short-circuited due to a failure, the second and fourth switches SW2 and SW4 are maintained in the turned-off state in accordance with the above-described initializing operation, When turned on, a closed loop as shown by (1) in Fig. 2 is formed. Accordingly, the control unit ECU can sense the inrush current through the current sensor ISEN to determine the failure of the first switch SW1.

If the first switch SW1 is not in failure, the first switch SW1 is maintained in the turn-off state in accordance with the above-described initializing operation, so that a closed loop as shown by (1) in Fig. 2 is not formed. Therefore, the control unit ECU can determine that the first switch SW1 is in a normal state because the inrush current is not sensed in the current sensor ISEN.

When the control unit ECU turns on the third switch SW3, the third switch SW3 can be turned on through the PWM control. That is, when the control unit (ECU) turns on the third switch (SW3) through the high-level control signal, there is a possibility that the converter element including the switch may be burned out due to the continuous rush current according to the closed loop. The third switch SW3 is turned on through the PWM pulse signal at which the level (turn-on) and the low-level (turn-off) are switched, thereby preventing the converter element from being burned out due to the continuous inrush current. The above-described process of turning on the switch through the PWM control can be equally applied to the operation of turning on a switch other than the switch to be subjected to the fault determination, which will be described below.

Next, when the malfunction determination switch is the second switch SW2, the control unit ECU turns on the third switch SW3. When the rush current is sensed by the current sensor ISEN, the second switch SW2 ) Can be judged as a failure.

That is, when the second switch SW2 is short-circuited due to a failure, since the first and fourth switches SW1 and SW4 are maintained in the turned-off state in accordance with the above-described initializing operation, the third switch SW3 When turned on, a closed loop as shown by 2 in Fig. 2 is formed. Accordingly, the control unit ECU can sense the inrush current through the current sensor ISEN to determine the failure of the second switch SW2.

If the second switch SW2 is not in failure, the second switch SW2 is maintained in the turn-off state in accordance with the above-described initializing operation, so that a closed loop shown in Fig. Therefore, the control unit ECU can determine that the second switch SW2 is in a normal state because the inrush current is not sensed in the current sensor ISEN.

Next, when the malfunction determination switch is the third switch SW3, the control unit ECU turns on the first switch SW1, and when the inrush current is sensed by the current sensor ISEN, the third switch SW3 ) Can be judged as a failure.

That is, when the third switch SW3 is short-circuited due to a failure, the second and fourth switches SW2 and SW4 are maintained in the turned-off state in accordance with the above-described initializing operation, When turned on, a closed loop as shown by (1) in Fig. 2 is formed. Accordingly, the control unit ECU can sense the inrush current through the current sensor ISEN to determine the failure of the third switch SW3.

If the third switch SW3 is not in failure, the third switch SW3 is maintained in the turned-off state in accordance with the above-described initializing operation, so that a closed loop as shown by (1) in Fig. 2 is not formed. Therefore, the control unit ECU can determine that the third switch SW3 is in the steady state because the inrush current is not sensed in the current sensor ISEN.

Next, when the malfunction determination switch is the fourth switch SW4, the control unit ECU turns on the first switch SW1, and when the inrush current is sensed by the current sensor ISEN, the fourth switch SW4 ) Can be judged as a failure.

That is, when the fourth switch SW4 is short-circuited due to a failure, the second and third switches SW2 and SW3 are maintained in the turned-off state in accordance with the above-described initializing operation, When turned on, a closed loop as shown by 3 in Fig. 2 is formed. Accordingly, the control unit ECU can sense the inrush current through the current sensor ISEN to determine the failure of the fourth switch SW4.

If the fourth switch SW4 is not malfunctioning, the fourth switch SW4 is maintained in the turn-off state in accordance with the above-described initializing operation, so that a closed loop as shown by 3 in Fig. 2 is not formed. Therefore, the control unit ECU can determine that the fourth switch SW4 is in a normal state because the inrush current is not sensed in the current sensor ISEN.

The inrush current flowing through the closed loops (1) through (3) of FIG. 2 passes through the inductor (L). In general, since the inrush current generated by a short circuit terminal changes largely instantaneously, there is a problem that an expensive current sensor ISEN is required to detect a momentarily varying current. However, in the present embodiment, since the current flowing through the closed loops 1 to 3 passes through the inductor L, instantaneous change of the current can be suppressed. (V _L = L di / dt, v _L : Voltage across the inductor , L: inductance, and i: current flowing in the inductor). Therefore, the failure of the switch can be stably judged only by the current sensor ISEN provided in the existing power conversion system.

On the other hand, if it is determined that the switch to be fault-diagnosed is faulty, the control unit ECU can control the switch, not the fault, to prevent the burn-in of the converter element due to the continuous flow of the inrush current. If the inrush current is sensed by the current sensor ISEN and it is determined that the first switch SW1 is faulty, the control unit ECU turns off the third switch SW3 (Or by PWM control), it is possible to prevent the converter element from being burned by removing the continuous inrush current by changing the closed loop 1 into an open loop.

In the above, the process of determining whether the switch of the single-phase bidirectional converter has failed is described. The above-described method can also be applied to the case where the switch included in the bidirectional converter BC composed of the multi-phase converter shown in Fig. 3 is judged to be faulty. That is, the control unit ECU can further determine whether each switch included in the multi-phase converter in which a plurality of bidirectional converters BC are connected in parallel is faulty, and more specifically, each bidirectional converter BC constituting the multi- It is possible to determine whether each switch included in the multiphase converter is faulty by sequentially judging whether or not the switch included in the multiphase converter BC is faulty by each bidirectional converter BC. Although FIG. 3 shows a two-phase bidirectional converter as an example, the present embodiment can be similarly applied to a multi-phase converter such as four-phase, six-phase, and eight-phase.

4 is a flowchart illustrating a method of determining a switch failure in a bidirectional converter according to an exemplary embodiment of the present invention.

Referring to FIG. 4, a method for determining a switch failure of a bidirectional converter according to an embodiment of the present invention will be described. First, the control unit (ECU) initializes the first to fourth switches SW1 to SW4 by turning them off ).

Next, the control unit ECU turns on any one of the switches other than the failure determination target switch so that a loop connecting the battery of the main battery MB and the sub battery SB to the failure determination target switch is formed (S20 ). At this time, the control unit ECU can PWM-control any one of the switches other than the failure-judged switch to turn it on.

Subsequently, the control unit ECU determines whether the failure determination target switch is faulty based on the inrush current generated by the closed loop due to the switch turned on in step S20 (S30). The process for the control unit (ECU) to determine the failure of the switch for each failure target switch is the one described above, so a detailed description thereof will be omitted.

Subsequently, the control unit ECU determines whether or not each switch included in the multi-phase converter in which a plurality of bidirectional converters BC are connected in parallel is faulty (S40). That is, whether each switch included in each of the bidirectional converters BC constituting the multiphase converter is faulty or not is sequentially determined for each bidirectional converter BC to determine whether each switch included in the multiphase converter is faulty.

As described above, this embodiment can reduce the cost and simplify the power conversion system by eliminating the expensive sensor or the complex algorithm for determining the failure of the switch of the bidirectional converter, and can quickly replace and repair the failure switch, The stability of the system can be improved.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, I will understand. Accordingly, the true scope of the present invention should be determined by the following claims.

MB: Main battery
SB: Sub battery
BC: Bi-directional converter
SW1: first switch
SW2: second switch
SW3: third switch
SW4: fourth switch
L: Inductor
ISEN: current sensor
ECU:

Claims (2)

A main battery and a sub battery each having a low voltage power supply;
A second switch connected between the other terminal of the first switch and the negative terminal of the main battery, a second switch connected between the connection node of the first switch and the second switch, A third switch connected between the other terminal of the inductor and the positive terminal of the sub battery, a fourth switch connected between the inductor and the connection node between the third switch and the negative terminal of the sub battery, A bidirectional converter including a current sensor for sensing a current flowing in the inductor; And
And a controller for determining whether a failure determination target switch determined as any one of the first to fourth switches is faulty,
Wherein the control unit turns on any one of the switches other than the failure determination target switch so that a loop connecting the battery of the main battery and the sub battery to the failure determination target switch is formed, Determines whether or not the failure determination object switch is faulty based on an inrush current generated due to the formation of a closed loop,
Wherein,
The first to fourth switches are respectively turned off and initialized before turning on any one of the switches other than the fault determining object switch,
Wherein,
When the inrush current is sensed by the current sensor when the failure determination target switch is one of the first and second switches and the third switch is turned on by PWM (Pulse Width Modulation) control, The failure determining unit determines that failure of the failure determination target switch corresponding to any one of the first switch,
When the failure determination target switch is the first switch, when the inrush current flowing through the first closed loop formed by turning on the third switch by PWM control is sensed by the current sensor, the failure of the first switch However,
When the failure determination target switch is the second switch, when the inrush current flowing through the second closed loop formed by turning on the third switch by PWM control is sensed by the current sensor, the failure of the second switch However,
And when the inrush current is sensed by the current sensor when PWM control of the first switch is turned on when the switch to be subjected to the fault determination is any one of the third and fourth switches, It is determined that there is a malfunction of the switch to be subjected to the malfunction determination,
When the inrush current flowing through the first closed loop formed by PWM control and turning on the first switch is sensed by the current sensor when the switch to be subjected to the fault determination is the third switch, And,
When the failure determination target switch is the fourth switch, when the inrush current flowing in the third closed loop formed by turning on the first switch by PWM control is sensed by the current sensor, However,
Wherein the first closed loop is a closed loop for connecting the main battery, the first switch, the inductor, the third switch, and the sub battery,
The second closed loop is a closed loop connecting the second switch, the inductor, the third switch, and the sub battery,
The third closed loop is a closed loop connecting the main battery, the first switch, the inductor, and the fourth switch,
Wherein the controller further determines whether each switch included in the multi-phase converter in which a plurality of the bidirectional converters are connected in parallel is faulty,
Wherein each of the bidirectional converters determines whether each switch included in each of the bidirectional converters constituting the multiphase converter is faulty or not, for each of the bidirectional converters, Switch failure determination device.
A main battery and a sub battery each having a low voltage power supply; And
A second switch connected between the other terminal of the first switch and the negative terminal of the main battery, a second switch connected between the connection node of the first switch and the second switch, A third switch connected between the other terminal of the inductor and the positive terminal of the sub battery, a fourth switch connected between the inductor and the connection node between the third switch and the negative terminal of the sub battery, And a bidirectional converter including a current sensor for sensing a current flowing through the inductor, the method comprising the steps of:
The control unit turns off and initializes the first to fourth switches, respectively;
The control unit turns on any one of the switches other than the failure determination target switch so that a loop connecting the battery of the main battery and the sub battery to the failure determination target switch is formed, Is one of the first to fourth switches; And
Determining whether the failure determination target switch is faulty based on an inrush current generated by forming a closed loop due to the switch being turned on;
Lt; / RTI &gt;
In the turning-on step,
(a) if the failure determination target switch is one of the first and second switches, the third switch is PWM (Pulse Width Modulation) controlled to turn on,
(b) when the failure determination target switch is any one of the third and fourth switches, the first switch is PWM-controlled to turn on,
In the determining step,
In the step (a) of turning on the switch, when the inrush current is sensed by the current sensor, it is determined that the failure determination target switch corresponding to one of the first and second switches is faulty,
When the failure determination target switch is the first switch, when the inrush current flowing through the first closed loop formed by turning on the third switch by PWM control is sensed by the current sensor, the failure of the first switch However,
When the failure determination target switch is the second switch, when the inrush current flowing through the second closed loop formed by turning on the third switch by PWM control is sensed by the current sensor, the failure of the second switch However,
In the step (b) of turning on the switch, when the inrush current is sensed by the current sensor, it is determined that the failure determination switch corresponding to one of the third and fourth switches is faulty,
When the inrush current flowing through the first closed loop formed by PWM control and turning on the first switch is sensed by the current sensor when the switch to be subjected to the fault determination is the third switch, And,
When the failure determination target switch is the fourth switch, when the inrush current flowing in the third closed loop formed by turning on the first switch by PWM control is sensed by the current sensor, However,
Wherein the first closed loop is a closed loop for connecting the main battery, the first switch, the inductor, the third switch, and the sub battery,
The second closed loop is a closed loop connecting the second switch, the inductor, the third switch, and the sub battery,
The third closed loop is a closed loop connecting the main battery, the first switch, the inductor, and the fourth switch,
Wherein the control unit further determines whether or not each switch included in the multi-phase converter in which a plurality of the bidirectional converters are connected in parallel is faulty, and determines whether the switch included in each bidirectional converter constituting the multi- Further comprising determining sequentially for each of the converters, and further determining whether each of the switches included in the multi-phase converter is faulty.

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