KR20210028312A - A device and a method for diagnosing error and predicting durability of an inverter system in a green car - Google Patents

Abstract

The present invention relates to a device and a method for diagnosing a fault and predicting durability of an inverter system of an environmental vehicle. The inverter system includes: a gate circuit for controlling a phase change operation to allow a DC voltage supplied from a battery to be output as voltage and current having a variable frequency; a power module including a plurality of power switching elements, and performing phase change by control of the gate circuit; and a diagnostic module for independently analyzing current for each phase output from the power module to determine whether the power module is faulty. The diagnostic module detects voltage and a temperature in accordance with any one or at least one phase current output in a sine wave form from the power module through injection of a high-frequency current when a vehicle starts, and performs a protective function of the power module by determining the power module as faulty when a detected voltage value exceeds a preset reference voltage value, or a detected temperature value exceeds a present reference temperature value. According to the present invention, a driver can recognize a fault in advance, such that a problem (e.g., reduced output, engine stop, etc.) during vehicle operation can be prevented.

Description

Device and method for diagnosing faults and predicting durability of environmental vehicle inverter systems {A DEVICE AND A METHOD FOR DIAGNOSING ERROR AND PREDICTING DURABILITY OF AN INVERTER SYSTEM IN A GREEN CAR}

The present invention relates to a fault diagnosis and durability life prediction method and apparatus through detection of a power module deterioration in an environmental vehicle inverter system, and more particularly, driving of a power module and a power module, which are switching elements of an inverter system for motor control. In the gate board configuration for, the present invention relates to a method and apparatus for detecting and predicting a durability life of a power module by detecting a change in static characteristics of the power module and a thermal resistance (Rth) deterioration rate.

In order to operate a driving motor of an eco-friendly vehicle such as a hybrid vehicle or an electric vehicle, a power module that adequately transfers current supplied from a high voltage battery to a driving motor in an inverter system and a gate circuit for driving the power module are essential.

The power module is a switching element or a switching semiconductor for motor control and performs a turn-off (ie, gate-off) switching operation, and includes an IGBT, a MOSFET, and the like. In addition, the gate circuit is a circuit material such as a power supply, a current buffer, and fault detection for making an appropriate current and voltage for on/off switching. Vce (IGBT) or Vds (MOSFET) can be determined by the forward characteristic curve according to the switch conduction current of the power module, and the deterioration rate of the thermal resistance Rth of the power module can also be detected.

Conventionally, the life of the power module (IGBT, MOSFET), which is an inverter power switching element applied to a vehicle, was not detected through a separate device or logic, and the usable durability life of the power module within the durability warranty period was determined according to the actual vehicle durability cycle during development. Predicted. As described above, since there has not been a method and device for real-time detection of the deterioration of the power module through a separate device or logic in the related art, starting off or not starting, depending on the endurance of the power module, limiting the maximum output during operation, etc. There was a problem that inconvenience was caused.

The present invention is to solve the problems of the prior art described above, and an object of the present invention is to express the presence or absence of an abnormality to the driver even if the endurance of the power module is exceeded, thereby causing inconveniences such as turning off or impossible to start, and limiting the maximum output during driving. To this end, we propose a method and apparatus for performing fault diagnosis by detecting the degree of degradation of Vce(sat) (IGBT) and thermal resistance (Rth) of a power module.

The technical problem to be achieved in the present invention is not limited to the technical problem mentioned above, and other technical problems not mentioned can be clearly understood by those of ordinary skill in the technical field to which the present invention belongs from the following description. There will be.

In order to solve the above technical problems, according to an embodiment of the present invention, a fault diagnosis of an environmental vehicle including an inverter system that configures an engine and a motor as power sources, and controls the driving speed and torque of the motor according to driving requirements An apparatus, wherein the inverter system comprises: a gate circuit for controlling a phase change operation such that a DC voltage supplied from a battery is output as a voltage and a current having a variable frequency; A power module comprising a plurality of power switching elements and performing phase conversion under control of the gate circuit; And a diagnostic module that independently analyzes each phase current output from the power module to determine whether the power module is faulty, wherein the diagnostic module is in the form of a sinusoidal wave in the power module through high-frequency current injection when the vehicle is started. When the voltage and temperature according to one or more of the output phase currents are sensed, and the detected voltage value exceeds a preset reference voltage value or the detected temperature value exceeds a preset reference temperature value, the power module It is characterized in that it determines as a failure and performs a protection function of the power module.

According to an embodiment, the diagnostic module includes: a current measuring unit for measuring a current for each phase output through the high-frequency current injection from the power module; A failure determination unit that independently analyzes the current for each phase applied from the current measurement unit and performs individual failure diagnosis by detecting voltage and temperature according to the current for each phase; And a driving determination unit determining whether to perform a protection function or to perform a normal start according to a determination result of the failure determination unit.

In addition, according to an embodiment of the present invention, in an environmental vehicle including an inverter system that configures an engine and a motor as power sources and controls the driving speed and torque of the motor according to a driving request, the power included in the inverter system A method of diagnosing a failure of a module includes: injecting a high-frequency current when starting a vehicle; Sensing a voltage and temperature according to one or more phase currents output from the power module in the form of a sine wave through the high-frequency current injection; Determining whether the sensed voltage value exceeds a preset reference voltage value or whether the sensed temperature value exceeds a preset reference temperature value; And if it is determined that the detected voltage value exceeds a preset reference voltage value or the detected temperature value exceeds a preset reference temperature value, determining that the power module has failed and performing a protection function of the power module. It characterized in that it comprises a.

According to an embodiment, when it is determined that the sensed voltage value does not exceed a preset reference voltage value and the sensed temperature value does not exceed a preset reference temperature value, performing a normal start-up and output operation. can do.

According to the apparatus and method for diagnosing faults and predicting durability life of an environmental vehicle inverter system according to the present invention, it is possible to recognize a fault in advance to a driver through fault diagnosis and durability life determination of a power module. There is an effect that can prevent problems during operation in advance.

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

BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings are provided to aid understanding of the present invention, and provide embodiments of the present invention together with a detailed description. However, the technical features of the present invention are not limited to a specific drawing, and features disclosed in each drawing may be combined with each other to constitute a new embodiment.
1 is a diagram showing a schematic configuration of an environmental vehicle according to an embodiment of the present invention.
2 is a diagram showing a detailed configuration of a diagnostic module in a fault diagnosis apparatus of an environmental vehicle inverter system according to an embodiment of the present invention.
3 is a graph illustrating outputting a three-phase sinusoidal wave when a high-frequency current is injected according to an embodiment of the present invention.
4 is a graph showing an ice current and Vce according to Tj according to a static characteristic of a power module according to an embodiment of the present invention.
5 is a schematic diagram showing a prediction model of a power module junction temperature through conduction/switching loss and thermal resistance (Rth) according to an embodiment of the present invention.
6 is a cross-sectional view illustrating an increase in thermal resistance (Rth) during peeling and cracking of solders according to an embodiment of the present invention.
7 is a flowchart illustrating a method of diagnosing a failure and predicting a durability life of an environmental vehicle inverter system according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the contents described in the accompanying drawings. However, the present invention is not limited or limited by exemplary embodiments. The same reference numerals shown in each of the drawings indicate members that perform substantially the same function.

Objects and effects of the present invention may be naturally understood or more clearly understood by the following description, and the objects and effects of the present invention are not limited only by the following description. In addition, in describing the present invention, when it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

1 is a diagram showing a schematic configuration of an environmental vehicle according to an embodiment of the present invention.

As can be seen from FIG. 1, the environmental difference is composed of a motor 100 as a driving source, an inverter system 103 including a motor control unit (MCU), and a high voltage battery 102.

The motor 100 is operated as a motor and a generator, and the driving speed and driving torque are controlled according to the control of the MCU, and the motor 100 is operated as a generator in the regenerative braking control according to the deceleration to recover the regenerative energy according to the deceleration, and the high voltage battery 102 To charge. The motor 100 exhibits maximum efficiency and characteristics by determining a driving mode and an output torque according to a driving situation.

The MCU adjusts the driving speed and driving torque for controlling the general operation of the motor 100 under the control of a hybrid controller (not shown) connected to the network.

The inverter system 103 includes a control unit (not shown) that controls the phase change operation of the power module 101 so that the DC voltage supplied from the high voltage battery 102 is output as a voltage and current having a variable frequency, and an inverter. It is composed of a power module 101 that performs phase change under the control of the controller, a capacitor, and a main relay (not shown). The main relay regulates the input/output voltage of the high-voltage battery 102, and the capacitor stores the voltage supplied from the high-voltage battery 102 to the motor 100 according to the ON of the main relay to control the voltage supplied to the motor 100. Keep it stable.

The power module 101 typically has a pair of upper arm and lower arm (U Top and U Bottom / V Top and V Bottom / W Top and W Bottom) It consists of 3 pairs and 6 power switch elements to output a current of three phases consisting of U, V, and W phases.

Accordingly, the upper arm is constituted by the first power switch element UT, the second power switch element VT, and the third power switch element WT, and the fourth power switch element UB and the fifth power switch element ( VB) and a sixth power switch element WB constitute a lower arm.

The power switch device may be applied as a MOSFET or an Insulated Gate Bipolar Transistor (IGBT).

According to an embodiment of the present invention, in order to detect the durability life of the power module 101 of the inverter system 103, the thermal resistance (Rth) degradation logic of the power module 101 and each switch element (UT, VT, We present a technique for Vce(sat) parameter sensing of WT, UB, VB, WB).

2 is a diagram showing a detailed configuration of a diagnostic module in a fault diagnosis apparatus of an environmental vehicle inverter system according to an embodiment of the present invention.

As can be seen from FIG. 2, the diagnostic module according to an embodiment of the present invention includes a circuit 201 for receiving Vce(sat) output from a power module, and a circuit 201 for receiving a junction temperature Tj of the power module ( 202) and MCU 204.

Three-phase (U, V, W phase) current is generated in the power switch element (IGBT) and motor through high-frequency current injection in the ignition device on state (vehicle stopped state) before starting, and accordingly, 6 phase (UT , VT, WT, UB, VB, WB phase) Ice current path is formed in the power switch element (IGBT). As a result, Vce (sat) is generated in the power switch element and the NTC (Negative Temperature Coefficient) changes (that is, the temperature rises). Here, the theoretical detailed design concept related to high-frequency current injection will be described as a three-phase sine wave having the same frequency and amplitude when injecting a DQ high-frequency current with a phase difference of 90 degrees in a stationary state (rotator position fixed). , This is illustrated in detail in the graph of FIG. 3.

Returning to FIG. 2, the diagnostic module receives Vce (sat) generated from the power module through the circuit 201 receiving Vce (sat), and receives the junction temperature (Tj) of the power module. Through 202, the NTC change (i.e., temperature rise) is detected. In the diagnostic module, Vce (sat) and temperature of the sensed power switch element are provided to the MCU 204.

The MCU 204 determines whether the value applied from the circuit 201 receiving the Vce(sat) input and the circuit 202 receiving the junction temperature of the power module exceeds a reference value previously stored in the CPU. , Execute the protective function or normal start according to the result of the judgment.

To determine whether a value applied to the MCU 204 of the diagnostic module exceeds a reference value, a graph of static characteristics of the power module as shown in FIG. 4 is used. That is, FIG. 4 is a graph showing Ice of the power module and Vce according to the junction temperature Tj in relation to the static characteristics of the power module according to an embodiment of the present invention. As can be seen from the graph of FIG. 4, the specific value of Vce(sat) of the power module is determined by current and temperature.

The MCU 204 stores a characteristic reference value considering power module distribution in the CPU in advance, and receives the Vce(sat) voltage of the power module detected after high-frequency current injection. After that, the inputted Vce(sat) value (input value) is compared with the Vce=F(Tj, I) matrix value (reference value) previously stored in the CPU, and the input value exceeds the previously stored reference value. If so, it is judged as a failure of the power module.

In this regard, referring to the graph of FIG. 4, when injecting the reference current (Iref) at the power module junction temperature Tj = 25°C, the reference Vce(sat) value ( That is, V _{CE0y_25°C} / V _{CE0x_25°C} ) are determined respectively. At this time, if the value of Vce(sat),maximum (V _{CE0x_25℃} ) determined from the distribution of the power module is exceeded, it is determined as a failure of the power module.

In addition, the diagnostic module diagnoses a failure of the power module through the temperature detected by the power module NTC temperature sensor and determines whether or not the durability life is exceeded. That is, the power module NTC has a resistance value for each temperature, and the power module junction temperature (Tj) is predicted from the sensed resistance value to perform output limiting and protection operation. In this regard, a prediction model of the power module junction temperature Tj through conduction/switching loss and thermal resistance Rth according to an embodiment of the present invention is schematically shown in FIG. 5.

6 is a cross-sectional view illustrating an increase in thermal resistance (Rth) during peeling and cracking of solders according to an exemplary embodiment of the present invention.

Referring to FIG. 6, when peeling of the solder joints 604 and 605 occurs beyond the designed target endurance life, the internal impedance increases, and accordingly, the thermal resistance Rth increases, and eventually, the power module The junction temperature Tj of the power semiconductor (chip) rises above the design value. Using this principle, power module life exceeded and fault diagnosis is performed when the estimated temperature value previously stored in the CPU is exceeded from the heat estimation model as shown in FIG. 5 through high-frequency current injection before initial start-up. It is done.

More specifically, the diagnostic module stores the characteristic reference value in the CPU in advance in the MCU 204, and after high-frequency current injection, the NTC change in the circuit 202 receiving the junction temperature Tj of the power module (that is, the temperature Rise), and the NTC temperature value detected by the MCU 204 is input. After that, the MCU 204 compares the received NTC temperature value (input value) with the estimated temperature value (reference value) previously stored in the CPU, and when the input value exceeds the preset reference value, the power module It will be judged as a failure.

7 is a flowchart illustrating a method of diagnosing a fault and predicting a durability life of an environmental vehicle inverter system according to an embodiment of the present invention.

In a state in which the ignition device of the environmental vehicle to which the present invention is applied is turned on (S701) and the main-relay is turned on (S702), after the preceding function (eg, current sensor failure detection, offset correction, etc.) is performed (S703). Then, a current command, that is, a high-frequency small signal is applied (S704). After that, the diagnostic module measures and detects the Vce(sat) voltage and NTC temperature of the power module, and stores the detected voltage and temperature values with the levels of the matrix (i.e., reference voltage value and reference temperature value) previously stored in the CPU. Compare (S705). As a result of the comparison in step S705, when the detected voltage value exceeds the reference voltage value or the detected temperature value exceeds the reference temperature value, the diagnostic module diagnoses the power module as abnormal, that is, exceeding the endurance life and malfunctioning. , To perform the protection function of the power module (S706). In addition, as a result of the comparison in step S705, if the detected voltage value does not exceed the reference voltage value and the detected temperature value does not exceed the reference temperature value, the diagnostic module diagnoses the power module as normal, and the normal startup and The output operation is performed (S707).

Through the above power module fault diagnosis and endurance determination technique, it is possible to recognize a fault in advance to the driver, and accordingly, there is an advantage that problems (e.g., power reduction, start-off, etc.) during vehicle operation can be prevented in advance. .

Although the present invention has been described in detail through exemplary embodiments above, those of ordinary skill in the art to which the present invention pertains will understand that various modifications can be made to the above-described embodiments without departing from the scope of the present invention. will be. Therefore, the scope of the present invention is limited to the described embodiments and should not be determined, and should be determined by all changes or modifications derived from the claims and the concept of equality as well as the claims to be described later.

Claims (4)

In an environmental vehicle failure diagnosis apparatus comprising an inverter system comprising an engine and a motor as power sources and controlling a driving speed and torque of the motor according to a driving request, the inverter system,
A gate circuit for controlling a phase change operation so that the DC voltage supplied from the battery is output as a voltage and a current having a variable frequency;
A power module comprising a plurality of power switching elements and performing phase conversion under control of the gate circuit; And
And a diagnostic module that independently analyzes the current for each phase output from the power module to determine whether the power module has failed,
The diagnostic module detects voltage and temperature according to any one or more phase currents output in the form of a sinusoid from the power module through high-frequency current injection at vehicle start-up, and the detected voltage value exceeds a preset reference voltage value. Or when the detected temperature value exceeds a preset reference temperature value, it is determined as a failure of the power module and a protection function of the power module is performed. The method of claim 1, wherein the diagnostic module,
A current measuring unit that measures a current for each phase output through the high-frequency current injection from the power module;
A failure determination unit that independently analyzes the current for each phase applied from the current measurement unit and performs individual failure diagnosis by detecting voltage and temperature according to the current for each phase; And
An operation determination unit that determines whether to perform a protection function or to perform a normal start according to the determination result of the failure determination unit
An apparatus for diagnosing a failure of an environmental vehicle, comprising: a. In a method for diagnosing a failure of a power module included in the inverter system in an environmental vehicle including an inverter system comprising an engine and a motor as power sources and controlling a driving speed and torque of the motor according to a driving request,
Injecting a high-frequency current when starting the vehicle;
Sensing voltage and temperature according to one or more phase currents output in the form of a sinusoid from the power module through the high-frequency current injection;
Determining whether the sensed voltage value exceeds a preset reference voltage value or whether the sensed temperature value exceeds a preset reference temperature value; And
If it is determined that the detected voltage value exceeds the preset reference voltage value or the detected temperature value exceeds the preset reference temperature value, determining that the power module has failed and performing a protection function of the power module. A method for diagnosing a failure of an environmental vehicle to include. The method of claim 3,
When it is determined that the detected voltage value does not exceed a preset reference voltage value and the detected temperature value does not exceed a preset reference temperature value, performing a normal start-up and output operation is further included. How to diagnose faults.

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