KR102250973B1 - Apparatus for controlling igbt of traction inverter of railway vehicle and method thereof - Google Patents

Abstract

The present invention relates to an apparatus for controlling a power semiconductor element of a propulsion inverter for a railway vehicle, comprising: a speed determination unit for determining a speed of a railway vehicle; An initial switching frequency selection unit for selecting a designated minimum switching frequency when the railway vehicle is at zero speed; A variable switching frequency selection unit configured to increase and select a switching frequency in response to an increase in the vehicle speed of the railway vehicle at the zero speed; And a driving unit for switching a power semiconductor element based on a switching frequency selected by the initial switching frequency selection unit and the variable switching frequency selection unit in response to the case where the speed of the railway vehicle is 0 and not the 0 speed. Includes.

Description

Power semiconductor device control device and method of propulsion inverter for railroad vehicles {APPARATUS FOR CONTROLLING IGBT OF TRACTION INVERTER OF RAILWAY VEHICLE AND METHOD THEREOF}

The present invention relates to an apparatus and method for controlling a power semiconductor element of a propulsion inverter for a railway vehicle, and more particularly, by changing the switching frequency of the power semiconductor element of the propulsion inverter when the railway vehicle is initially started, it is possible to reduce the range of temperature change. It relates to an apparatus and method for controlling a power semiconductor element of a propulsion inverter for a railway vehicle, which enables the life of a semiconductor element to be extended.

In general, the endurance life of existing railroad vehicles was collectively managed for about 25 years, but in recent years, research on the endurance life of individual devices used in railroad vehicles is steadily progressing, and the durability of each device is reasonable suitable for the maintenance and replacement cycle of the site. As the time limit has been proposed, railroad agencies have adopted it and created guidelines to carry out maintenance and replacement.

Since these railway vehicles are operated by receiving electric power from a catenary line (or'trolley line') installed along the track, it is equipped with a power converter that converts the electric power supplied through the catenary line according to the used power of the railway vehicle. . In addition, such a power converter includes a plurality of power switching devices such as an Insulated Gate Bipolar Transistor (IGBT) for converting or inverting power.

Here, in the propulsion inverter, which is a core electronic component of the railway vehicle, the endurance life of a switching device (or power semiconductor device), which is a main device, is currently used as the endurance life of the propulsion inverter.

That is, the life of the propulsion inverter is determined by the power semiconductor device, which is the most vulnerable device among the components, and the life of the power semiconductor device is determined by the operating characteristics (switching frequency, current, frequency, etc.) of the propulsion system. It is determined according to (T ) and the amount of change in operating temperature ( dT).

The life model of the power semiconductor device is expressed as Equation 1 below.

Accordingly, in order to increase the life time of the power semiconductor device (ie, to extend the life of the propulsion inverter), the operating average temperature ( T ) must be lowered or the operating temperature change amount ( dT ) must be reduced.

At this time, the method of lowering the operating average temperature (T ) while satisfying the voltage and current requirements includes reducing the loss of the power semiconductor by changing the switching frequency or improving the heat dissipation performance to keep the temperature rise low. Problems such as increase in the size and weight of the heat pipe occur.

The background technology of the present invention is disclosed in Korean Patent Laid-Open Publication No. 10-2010-0120805 (published on November 17, 2010, a preventive diagnosis apparatus and method for power elements of a railway vehicle).

According to an aspect of the present invention, the present invention was created to solve the above problems, and by changing the switching frequency of the power semiconductor element of the propulsion inverter when the railway vehicle first starts, it is possible to reduce the range of temperature change. An object thereof is to provide an apparatus and method for controlling a power semiconductor element of a propulsion inverter for a railroad vehicle, which enables the life of a semiconductor element to be extended.

An apparatus for controlling a power semiconductor element of a propulsion inverter for a railway vehicle according to an aspect of the present invention includes: a speed determination unit for determining a speed of a railway vehicle; An initial switching frequency selection unit that selects a designated minimum switching frequency when the railway vehicle is at zero speed; A variable switching frequency selection unit configured to increase and select a switching frequency in response to an increase in the vehicle speed of the railway vehicle at the zero speed; And a driving unit for switching a power semiconductor element based on a switching frequency selected by the initial switching frequency selection unit and the variable switching frequency selection unit in response to the case where the speed of the railway vehicle is 0 and not the 0 speed. It characterized in that it includes.

In the present invention, it characterized in that it further comprises a; switching frequency limiting unit for limiting the switching frequency so that the switching frequency increased by the variable switching frequency selection unit does not increase than a specified switching frequency limit value.

In the present invention, a control unit for integrating functions of the speed determination unit, the initial switching frequency selection unit, and the variable switching frequency selection unit; wherein the control unit is implemented including a function of a switching frequency limiting unit. do.

In the present invention, when the railroad vehicle is at zero speed, the minimum switching frequency is 400 Hz.

In the present invention, the switching frequency limit value is characterized in that 800Hz.

A method for controlling a power semiconductor element of a propulsion inverter for a railroad vehicle according to another aspect of the present invention includes: determining, by a control unit, a speed of the railroad vehicle; Selecting, by the control unit, a designated minimum switching frequency when the railroad vehicle is at zero speed; Selecting, by the control unit, increasing a switching frequency in response to an increase in the vehicle speed of the railroad vehicle at the zero speed; And switching, by the control unit, a power semiconductor element through a driving unit based on a switching frequency selected in response to a case where the speed of the railroad vehicle is 0 and not the 0 speed.

In the present invention, the control unit increases the switching frequency in response to the increase of the vehicle speed of the railway vehicle at the zero speed, but limits the switching frequency so that the increasing switching frequency does not increase above a specified switching frequency limit value. It characterized in that it further comprises a;

In the present invention, when the railroad vehicle is at zero speed, the minimum switching frequency is 400 Hz.

In the present invention, the switching frequency limit value is characterized in that 800Hz.

According to an aspect of the present invention, the present invention changes the switching frequency of the power semiconductor element of the propulsion inverter when the railway vehicle first starts to reduce the temperature variation range, thereby extending the life of the power semiconductor element.

1 is an exemplary view of a graph shown to explain the temperature change of a power semiconductor element when driving a propulsion inverter at a specified constant switching frequency in a low-speed region of a conventional railway vehicle.
2 is an exemplary view showing a schematic configuration of an apparatus for controlling a power semiconductor element of a propulsion inverter for a railway vehicle according to an embodiment of the present invention.
3 is an exemplary view of a graph showing a change in temperature of a power semiconductor device when driving by changing a switching frequency of a propulsion inverter in a low speed region of a railroad vehicle according to the present embodiment.
4 is an exemplary view showing an RC fourth thermal model of a power semiconductor device in FIG. 2.

Hereinafter, an embodiment of an apparatus and method for controlling a power semiconductor element of a propulsion inverter for a railroad vehicle according to the present invention will be described with reference to the accompanying drawings.

In this process, the thickness of the lines or the size of components shown in the drawings may be exaggerated for clarity and convenience of description. In addition, terms to be described later are terms defined in consideration of functions in the present invention, which may vary according to the intention or custom of users or operators. Therefore, definitions for these terms should be made based on the contents throughout the present specification.

As described above, the voltage/current of the conventional railway vehicle propulsion inverter is determined by the motor to be coupled, the temperature rise of the power semiconductor element is determined by the generated loss, and the loss of the power semiconductor element is the switching frequency of the propulsion inverter. Is determined by

At this time, the switching frequency of the conventional railway vehicle propulsion inverter is changed by the vehicle speed. In the low-speed section, the inverter operates at a constant switching frequency to ensure precise control characteristics, and the speed of the railway vehicle increases. , V _dc /0.6365) is the fundamental wave frequency at which the switching frequency is applied to the motor after the switching frequency decreases from the point where the over-modulation region (e.g., modulation index = 0.907), and then from the one-pulse region (e.g., modulation index = 1). Becomes equal to

For reference, the fundamental frequency is an alternating current frequency of the current applied to the motor, and may increase to several hundred Hz in proportion to the speed.

At this time, the reason why the switching frequency is lowered in the conventional propulsion inverter as the speed of the railroad vehicle increases is because (1) the effect of the torque ripple generated by the motor on the railroad vehicle decreases as the speed increases (vibration generated by the vehicle itself). The factor is larger), (2) It is to reduce the overall loss that occurs in the power semiconductor device.

At this time, there is no room for further improvement in relation to the loss, as the conventional modulation method of the over-modulation region and the one-pulse region of the propulsion inverter generates a minimum loss.

However, the switching frequency used in the low speed region (generally the low voltage modulation index, that is, the low speed region with a modulation index of 0.907 or less) is a designated constant value and is not aimed at the minimum loss, but is the minimum value to secure control performance Is selected.

In general, as the propulsion inverter controls the AC current applied to the motor, the switching frequency is selected equal to or 0.5 times the control frequency in consideration of the current ripple, and the control frequency is selected at least 20 times the AC current frequency of the motor. Only smooth control is possible. Therefore, as the modulation index and speed are proportional, the control frequency and the switching frequency are determined according to the AC current frequency at the point where the modulation index becomes 0.907. For reference, the control frequency is a frequency of a control unit (eg, a microcomputer) and corresponds to twice the switching frequency.

However, when the electric motor is driven by using a specified constant switching frequency in the low speed region as described above, the temperature change of the power semiconductor element of the propulsion inverter appears as shown in (d) of FIG. 1. That is, in the initial driving of the propulsion inverter, as the frequency of the AC current is low, many switching occurs in the power semiconductor for one period, and a large amount of change in operating temperature ( dT ) (that is, the width of temperature change) is shown due to the accumulated loss.

Here, FIG. 1 is an exemplary view of a graph shown to explain a temperature change of a power semiconductor element when a propulsion inverter is driven at a designated constant switching frequency in a low-speed region of a conventional railway vehicle. Figure 1 (a) is a graph showing the motor speed (RPM), (b) is the c-phase current of the propulsion inverter, (c) is the switching frequency (Fsw), and (d) is the c-phase upper switch temperature (junction temperature). to be.

At this time, referring to (d) of FIG. 1, the temperature change width (i.e., the operating temperature change amount ( dT )) in the interval of 2 seconds to 4 seconds is that the maximum temperature is 56 degrees and the minimum temperature is 45 degrees, and the temperature change width gradually decreases. I can see that.

When the temperature change width (that is, the operating temperature change amount dT ) is large as described above, there is a great influence on reducing the life of the power semiconductor device. Therefore, in order to extend the life of the power semiconductor device, it is necessary to lower the operating temperature change ( dT ) (that is, the temperature change width) as little as possible.

Accordingly, in this embodiment, the lifespan of the power semiconductor element of the propulsion inverter can be extended by lowering the operating temperature change amount (dT ) (i.e., the temperature change width) compared to the conventional while changing the switching frequency in response to the speed of the railway vehicle (or electric motor). There are features that allow it.

2 is an exemplary view showing a schematic configuration of an apparatus for controlling a power semiconductor element of a propulsion inverter for a railway vehicle according to an embodiment of the present invention.

As shown in Figure 2, the power semiconductor element control device of the propulsion inverter for a railroad vehicle according to this embodiment, the speed determination unit 110, the initial switching frequency selection unit 120, the variable switching frequency selection unit 130, It includes a switching frequency limiting unit 140, and a driving unit 150.

The speed determination unit 110 determines (or detects) the speed of the railway vehicle.

For example, the speed of the railroad vehicle may be determined (or detected) through a pre-installed speed detection sensor (not shown), or may be determined by receiving speed information detected from an upper vehicle control unit (not shown).

The initial switching frequency selection unit 120 selects (or sets) a designated minimum switching frequency when the railway vehicle is at zero speed.

The variable switching frequency selection unit 130 selects (or sets) by varying (or increasing) a switching frequency in response to an increase in the vehicle speed of the railroad vehicle at zero speed.

For example, the minimum switching frequency or the switching frequency corresponding to the vehicle speed of the railway vehicle may be previously stored in an internal memory (not shown) in the form of a lookup table.

The switching frequency limiting unit 140 limits the switching frequency so that the switching frequency increased by the variable switching frequency selecting unit 130 does not increase more than a specified switching frequency limit value.

The driving unit 150 is selected by the initial switching frequency selection unit 120 and the variable switching frequency selection unit 130 in response to the speed of the railway vehicle (eg, 0 speed and non-zero speed) (or Switches the power semiconductor device (not shown) based on the set switching frequency.

At this time, the functions of the speed determination unit 110, the initial switching frequency selection unit 120, the variable switching frequency selection unit 130, and the switching frequency limiting unit 140 are integrated into the control unit 200 to be implemented. May be. Accordingly, the control unit 200 may integrally control each function of the components 110 to 140 through software.

As described above, it is necessary to change the switching frequency in order to reduce the amount of change in operating temperature dT of the power semiconductor device.

The relationship between the operating temperature change (dT) of the power semiconductor device and the switching frequency may be calculated through the loss of the power semiconductor device and thermal equivalent resistance (see FIG. 4).

4 is an exemplary view showing an RC fourth order thermal model of a power semiconductor device in FIG. 2. For reference, the loss (P _IGBT ) of the power semiconductor device (IGBT) is composed of a conduction loss ( P _IGBT,con ) and a switching loss ( P _IGBT,sw ), and is calculated as in Equations 2 and 3 below.

Here, V _CE(sat) is the current on the IGBT data sheet-the voltage that meets the current axis on the V _CE graph, R _o is the current-the slope of the V _CE graph, I _c is the current flowing through the IGBT, and D is the current flowing through the IGBT. It is the current rate, E _on and E _off are the values specified in the data sheet after being tested under V _dc,test conditions, and V _dc,real is the actual DC link voltage used.

The temperature of the _IGBT is calculated as the product of the loss (P IGBT) and the inferior equivalent resistance ( Z _th ), as shown in Figure 4, and can be expressed as Equation 4 below.

At this time, in order to reduce the conduction loss (P _IGBT,con ), the current (Ic ) and the current rate (D ) must be reduced, but in this case, the propulsion inverter cannot achieve the required torque performance.

Therefore, the conduction loss ( P _IGBT,con ) cannot be reduced.

However, among the variables related to the switching loss ( P _IGBT,sw ), the switching frequency ( f _sw ) can be changed to one that is not related to the torque performance required by the propulsion inverter.

Meanwhile, in order to reduce the amount of change in operating temperature dT , the maximum value of the temperature T _IGBT (t) of the power semiconductor device IGBT should be kept low.

In Equation 4, the thermal equivalent resistance ( Z _th ) can be interpreted as a filter composed of a resistor (R) and a capacitor (C), and the IGBT loss ( P _IGBT ) can be interpreted as an input value of the filter.

And since the temperature of the _IGBT (T IGBT (t) ) corresponds to the filter output, the maximum value of the input IGBT loss ( P _IGBT ) is required to calculate the maximum value, and the change shape of the IGBT loss (P _{IGBT) is current.} Since the shape of (Ic ) is the same, the gain and phase delay of the thermal equivalent resistance ( Z _{th ), which is a filter, are required.}

Here, the maximum value of the IGBT loss ( P _IGBT ) is the point at which the current (Ic ) becomes the maximum and is the point π/2 because a sinusoidal current is applied. In addition, the gain and phase delay of the thermal equivalent resistance ( Z _th ), which is a filter, must be calculated according to the fundamental wave frequency (f _b ) of the current, and can be expressed as a function such as Equations 5 and 6 below.

Using the above equations, the maximum temperature ( T _IGBT,max ) of the IGBT can be calculated as in Equation 7 below.

Here, I _c (t) can be expressed as I·sin(ωt) as a square wave function.

In the above equation, if the maximum temperature ( T _IGBT,max ) is selected as the amount of change in operating temperature ( dT ) to be maintained and expressed as a switching frequency (f _sw ), it is as shown in Equation 8 below.

In the case of applying Equation 8, when the fundamental frequency is low, the switching frequency is also lowered.If the switching frequency is too low, the minimum switching frequency in the controllable range is selected in consideration of the difficulty in controlling the motor, and the switching frequency is less than To prevent going down.

Equation 8 can also be expressed proportionally as in Equation 9 below.

Here, K _a is an equivalent constant.

3 is an exemplary diagram showing a temperature change of a power semiconductor device in a graph when the switching frequency is changed according to Equation 9 in FIG. 2.

That is, FIG. 3 is an exemplary view of a graph shown to explain a temperature change of a power semiconductor device when driving by changing a switching frequency of a propulsion inverter in a low speed region of a railroad vehicle according to the present embodiment. 3A is a graph showing the motor speed (RPM), (b) is the c-phase current of the propulsion inverter, (c) is the switching frequency (Fsw), and (d) is the c-phase upper switch temperature (junction temperature). to be. At this time, the minimum switching frequency is 400Hz.

Comparing the graph shown in (d) of FIG. 3 with the graph of (d) of FIG. 1, the range of temperature change (that is, the amount of change in operating temperature ( dT )) in the interval of 2 seconds to 4 seconds, the maximum temperature is 53 Degrees, it can be seen that the range of temperature change gradually decreases from 45 degrees at the minimum temperature. That is, it can be seen that the initial operating temperature change amount dT is reduced by 30% or more.

As described above, in this embodiment, the operating temperature change amount (dT ) (i.e., the temperature change width) is adjusted to be small by changing only the switching frequency of the power semiconductor element so that the control performance is not affected according to the operating conditions, thereby reducing the power semiconductor lifespan. It has the effect of extending and reducing the size of the heat pipe.

As described above, the present invention has been described with reference to the embodiments shown in the drawings, but this is only an example, and various modifications and other equivalent embodiments are possible from those of ordinary skill in the field to which the technology pertains. I will understand the point. Therefore, the technical protection scope of the present invention should be determined by the following claims. Also, the implementation described herein may be implemented in, for example, a method or process, an apparatus, a software program, a data stream or a signal. Although discussed only in the context of a single form of implementation (eg, only as a method), the implementation of the discussed features may also be implemented in other forms (eg, an apparatus or program). The device may be implemented with appropriate hardware, software and firmware. The method may be implemented in an apparatus such as a processor, which generally refers to a processing device including, for example, a computer, a microprocessor, an integrated circuit or a programmable logic device, or the like. Processors also include communication devices such as computers, cell phones, personal digital assistants (“PDAs”) and other devices that facilitate communication of information between end-users.

110: speed determination unit
120: initial switching frequency selection unit
130: variable switching frequency selection unit
140: switching frequency limiter
150: drive unit
200: control unit

Claims (9)

A speed determination unit that determines the speed of the railway vehicle;
An initial switching frequency selection unit for selecting a designated minimum switching frequency when the railway vehicle is at zero speed;
A variable switching frequency selection unit configured to increase and select a switching frequency in response to an increase in the vehicle speed of the railway vehicle at the zero speed; And
Including; a driving unit for switching the power semiconductor element based on the switching frequency selected by the initial switching frequency selection unit and the variable switching frequency selection unit in response to the case where the speed of the railway vehicle is 0 speed and not 0 speed. But,
The variable switching frequency selection unit,
Using Equation 8 below, the maximum temperature ( T _IGBT,max ) is selected as the operating temperature change amount ( dT ) to be maintained and set as the switching frequency (f _sw),
Using Equation 9 below, a power semiconductor element control device for a propulsion inverter for a railway vehicle, characterized in that the switching frequency is prevented from falling below this by selecting a minimum switching frequency in a controllable range.
(Equation 8)

(Equation 9)

Here, K _a is the equivalent constant, V _CE(sat) is the current on the IGBT data sheet-the voltage that meets the current axis on the V _CE graph, R _o is the current-the slope of the V _CE graph, and I _c is the current flowing through the IGBT , D is the current flow rate of the IGBT, E _on and E _off are the values specified in the data sheet after being tested under V _dc,test conditions, V _dc,real is the actual DC link voltage used, Z _th is the thermal equivalent resistance , f _b is the fundamental frequency of the current,

Is the gain of the thermal equivalent resistance according to the fundamental wave frequency ( f _{b) of the current,}

Denotes the phase delay of the thermal equivalent resistance according to the fundamental wave frequency ( f _{b) of the current.}
The method of claim 1,
A switching frequency limiting unit for limiting the switching frequency so that the switching frequency increased by the variable switching frequency selecting unit does not increase than a specified switching frequency limit value; a power semiconductor device control device for a propulsion inverter for a railway vehicle, further comprising.
The method of claim 1,
Includes; a control unit for integrating the functions of the speed determination unit, the initial switching frequency selection unit, and the variable switching frequency selection unit,
The control unit is a power semiconductor element control device of a propulsion inverter for a railway vehicle, characterized in that implemented including a function of a switching frequency limiting unit.
The method of claim 1,
The power semiconductor device control device of a propulsion inverter for a railroad vehicle, characterized in that the minimum switching frequency when the railroad vehicle is at 0 speed is 400Hz.
The method of claim 2, wherein the switching frequency limit value,
A power semiconductor element control device of a propulsion inverter for railway vehicles, characterized in that of 800Hz.
Determining, by the control unit, the speed of the railway vehicle;
Selecting, by the control unit, a designated minimum switching frequency when the railroad vehicle is at zero speed;
Selecting, by the control unit, increasing a switching frequency in response to an increase in the vehicle speed of the railroad vehicle at the zero speed; And
Including, by the control unit, switching the power semiconductor element through a driving unit based on a switching frequency selected in response to a case where the speed of the railroad vehicle is 0 and not the 0 speed,
The control unit,
Using Equation 8 below, the maximum temperature ( T _IGBT,max ) is selected as the operating temperature change amount ( dT ) to be maintained and set as the switching frequency (f _sw),
Using Equation 9 below, a power semiconductor element control method of a propulsion inverter for a railway vehicle, characterized in that the switching frequency is prevented from falling below this by selecting a minimum switching frequency in a controllable range.
(Equation 8)

(Equation 9)

Here, K _a is the equivalent constant, V _CE(sat) is the current on the IGBT data sheet-the voltage that meets the current axis on the V _CE graph, R _o is the current-the slope of the V _CE graph, and I _c is the current flowing through the IGBT , D is the current flow rate of the IGBT, E _on and E _off are the values specified in the data sheet after being tested under V _dc,test conditions, V _dc,real is the actual DC link voltage used, Z _th is the thermal equivalent resistance , f _b is the fundamental frequency of the current,

Is the gain of the thermal equivalent resistance according to the fundamental wave frequency ( f _{b) of the current,}

Denotes the phase delay of the thermal equivalent resistance according to the fundamental wave frequency ( f _{b) of the current.}
The method of claim 6,
Increasing the switching frequency in response to the increase in the vehicle speed of the railroad vehicle at the zero speed by the control unit, but limiting the switching frequency so that the increasing switching frequency does not increase above a specified switching frequency limit value; Power semiconductor element control method of a propulsion inverter for a railway vehicle, characterized in that.
The method of claim 6,
The power semiconductor device control method of a propulsion inverter for a railroad vehicle, characterized in that the minimum switching frequency when the railroad vehicle is at 0 speed is 400Hz.
The method of claim 7, wherein the switching frequency limit value,
A method for controlling a power semiconductor element of a propulsion inverter for a railway vehicle, characterized in that of 800Hz.

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