KR20220035728A - Igbt control apparatus and method - Google Patents

Abstract

An IGBT control device according to a preferred embodiment of the present invention includes a voltage measurement unit that measures the voltage across the IGBT when the IGBT is turned off, a comparison unit that calculates a rate of change per hour of the voltage across the IGBT, and a calculation result of the comparison unit. and a control unit that selects one resistor from among a plurality of resistors provided in advance and controls a relay so that the selected resistor is connected to the gate of the IGBT.

Description

IGBT control device and method {IGBT CONTROL APPARATUS AND METHOD}

The present invention relates to an IGBT control device and method, for example, to an IGBT control device and method used to control a vehicle motor.

Recently, automobile systems are becoming increasingly electric, and the electric vehicle market is growing accordingly.

Types of electric vehicles include EV (Electric Vehicle), HEV (Hybrid Electric Vehicle), and FCEV (Fuel Cell Electric Vehicle).

The driving operation of an electric vehicle can be achieved by stepping down the high-voltage battery voltage and supplying it to the vehicle driving motor.

IGBT (Insulated Gate Bipolar Transistor) semiconductor devices are used to control these vehicle driving motors.

IGBT is a switching device with a structure of a power MOSFET (metal oxide semi-conductor field effect transistor) and a bipolar transistor. It is a device with small driving power, high-speed switching, high breakdown voltage, and high current density. .

Conventionally, whether sectional control was possible was determined by the presence or absence of an IGBT sensor, and even if a sensor was present, sectional control was only possible if the Gate IC, IGBT sensor specifications, and system specifications were consistent.

When these IGBTs are turned off, the voltage (V_CE) between the collector and emitter oscillates irregularly and may deviate from the internal pressure of the component, and in this case, burnout may occur.

To solve this problem, the switching speed of the IGBT is controlled by varying it. However, in the case of IGBTs that do not have a built-in current sensor, there is a problem that they cannot be used in divided operation sections.

In the case of an IGBT with a built-in current sensor, it can be used by dividing the operation section, but there is a problem that deviations due to temperature occur, and if the consistency of the Gate IC and the IGBT is not correct, the operation section cannot be divided and used.

Meanwhile, the IGBT diagnosis and control method may include a diagnosis method using a current sensor and a desaturation method.

The diagnosis method using a current sensor is that when an IGBT's SC (Short to Circuit) occurs, a current flows through the shunt resistor at a certain rate from the current flowing through the IGBT. At this time, the voltage of the shunt resistor is monitored to diagnose OC (Over Current), This is how the SC diagnosis and overcurrent diagnosis switches operate.

In the desaturation method, when SC occurs in the IGBT, the voltage (V_CE) between the collector and emitter of the IGBT increases above the threshold voltage (Threshold), and at this time, the switch for SC diagnosis and overcurrent diagnosis operates.

Additionally, conventionally, correction of the IGBT diagnosis results is performed to improve the reliability of the IGBT diagnosis results. IGBT diagnostic correction methods include NTC (Negative Temperature Coefficient) and a method using a temperature sensor.

When NTC is applied when measuring the temperature of the IGBT, the voltage change rate of NTC is large. Diagnostic current according to temperature can be compensated by reading the NTC voltage from the MCU and mapping it with a diagnostic threshold.

When a temperature sensor (e.g., diode) is used when measuring the temperature of an IGBT, the temperature sensor voltage changes depending on the IGBT temperature, and at this time, the rate of change in voltage of the temperature sensor is small. The overcurrent diagnosis voltage is set based on the voltage of the temperature sensor, and level correction is performed by performing mapping through the IC function or MCU.

Conventionally, a current sensor or desaturation method is used to determine the overcurrent or short circuit state of the IGBT, but there are the following problems.

In the case of the desaturation method, SC diagnosis is only possible when a very high current flows through the IGBT, so there is a risk of burnout of the IGBT.

In the case of the current sensor method, there is a problem in that the diagnostic threshold varies because the voltage applied to the shunt resistance varies depending on the temperature of the IGBT. Additionally, there is a problem where diagnosis is not possible at the desired level depending on the current distribution ratio of the IGBT and current sensor.

Republic of Korea Patent No. 10-1911260

Accordingly, the present invention was developed in consideration of the above circumstances, and provides an IGBT control device and method that can control the switching speed for each desired operation section when controlling the IGBT, regardless of whether a temperature sensor and a current sensor are included inside the IGBT. The purpose is to

An IGBT control device according to a preferred embodiment of the present invention for achieving the above object includes a voltage measuring unit that measures the voltage at both ends of the IGBT when the IGBT is turned off; a comparison unit that calculates a rate of change per hour of the voltage at both ends of the IGBT; and a control unit that selects one resistor from among a plurality of resistors prepared in advance according to the calculation result of the comparison unit and controls a relay so that the selected resistor is connected to the gate of the IGBT.

The comparison unit may compare the voltage at both ends of the IGBT with a plurality of preset threshold voltages.

The plurality of threshold voltages may include a first threshold voltage and a second threshold voltage higher than the first threshold voltage.

The comparator outputs a high-level low trigger signal when the voltage at both ends of the IGBT is greater than or equal to the first threshold voltage, and outputs a high-level high trigger signal when the voltage at both ends of the IGBT is greater than or equal to the second threshold voltage. can do.

The control unit sets the point in time at which a certain time has elapsed based on the trigger point at which the low trigger signal of the high level is received as the first reference point, and sets the point in time at which a certain time has elapsed from the second reference point in time as the second reference point. You can set it.

If a rising edge of the high trigger signal occurs in a section past the second reference point, the control unit may determine a normal state and select a second resistor from among the plurality of resistors.

When a rising edge of the high trigger signal occurs in the section between the first reference point and the second reference point, the control unit may determine a high current state and select a third resistor from among the plurality of resistors.

When a rising edge of the high trigger signal occurs in the section between the trigger time and the first reference time, the control unit may determine an overcurrent state and select a fourth resistor from among the plurality of resistors.

The plurality of resistors may have different resistance values.

An IGBT control method according to a preferred embodiment of the present invention for achieving the above object includes a voltage measurement step of measuring the voltage at both ends of the IGBT when the IGBT is turned off; A comparison step of calculating the rate of change per hour of the voltage at both ends of the IGBT; A selection step of selecting one resistor from among a plurality of resistors prepared in advance according to the calculation in the comparison step; and a control step of controlling the relay so that the selected resistor is connected to the gate of the IGBT.

The comparison step includes a first comparison step of comparing the voltage at both ends of the IGBT and a first threshold voltage to output a low trigger signal, and a first comparison step of comparing the voltage at both ends of the IGBT and a second threshold voltage to output a high trigger signal. 2 May include a comparison step.

The selection step includes a first reference time point that is a certain time after the trigger time point when the voltage at both ends of the IGBT reaches the first threshold voltage, and a second time point that is a certain time point after the first reference time point. It may include a setting step for setting a reference point.

The selection step determines the state of the IGBT by considering the rising edge of the high trigger signal occurring at the trigger time, the first reference time, and the second reference time, and selects a resistor from among a plurality of resistors according to the determination result. You can choose either resistor.

According to the IGBT control device and method according to a preferred embodiment of the present invention, it is possible to control the switching speed for each desired operation section when controlling the IGBT, regardless of whether a temperature sensor and a current sensor are included within the IGBT.

1 is a block diagram of an IGBT control device according to a preferred embodiment of the present invention.
FIG. 2 is a diagram briefly illustrating the voltage measurement unit and comparison unit of FIG. 1.
FIG. 3 is a diagram showing an example of the output value of the comparison unit of FIG. 2.
FIG. 4 is a diagram for explaining a method of selecting the resistance of an IGBT gate in the control unit of FIG. 1.
Figure 5 is a diagram showing an example of the voltage between the collector and emitter of an IGBT.
Figure 6 is a flowchart of an IGBT control method according to a preferred embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. First, when adding reference numerals to components in each drawing, it should be noted that identical components are given the same reference numerals as much as possible even if they are shown in different drawings. In addition, preferred embodiments of the present invention will be described below, but the technical idea of the present invention is not limited or restricted thereto, and of course, it can be modified and implemented in various ways by those skilled in the art.

1 is a block diagram of an IGBT control device according to a preferred embodiment of the present invention.

Referring to FIG. 1, the IGBT control device 100 according to a preferred embodiment of the present invention controls the gate using the rate of change per hour (dV/dt) of the voltage between the collector and the emitter when the IGBT is turned off. It is characterized by selecting an appropriate resistance to be connected to.

This IGBT control device 100 includes a voltage measurement unit 110, a comparison unit 120, and a control unit 130.

When the IGBT is turned off, the voltage measurement unit 110 can measure the voltage between the collector and emitter of the IGBT (hereinafter referred to as the voltage at both ends of the IGBT). Here, the IGBT may be a switch circuit for controlling a vehicle driving motor, but is not limited thereto.

The comparator 120 may calculate the rate of change per hour of the voltage at both ends of the IGBT. The comparison unit 120 may compare the voltage at both ends of the IGBT with a plurality of preset threshold voltages to calculate the rate of change per hour. The comparison unit 120 may transmit at least two trigger signals according to the comparison result to the control unit 130.

The control unit 130 may select one resistor from among a plurality of resistors provided in advance according to the calculation result of the comparison unit 120. It is preferable that the plurality of resistors have different resistance values. The control unit 130 can select an appropriate resistance using the two trigger signals received from the comparison unit 120. The control unit 130 may control the relay so that the selected resistor is connected to the gate of the IGBT.

Through this, when the IGBT is turned off, even if peak voltage occurs due to the load connected to the IGBT, the generated peak voltage does not exceed the maximum allowable voltage of the voltage at both ends of the IGBT. Accordingly, the IGBT control device 100 can prevent damage to the IGBT.

Below, the configuration of the IGBT control device 100 will be described in detail.

FIG. 2 is a diagram briefly illustrating the voltage measurement unit and comparison unit of FIG. 1.

Referring to FIG. 2, the comparison unit 120 may include a first comparator 121 and a second comparator 123. A first threshold voltage (Vth1) may be applied to the first comparator 121, and a second threshold voltage (Vth2) may be applied to the second comparator 123. Here, the second threshold voltage (Vth2) has a higher voltage than the first threshold voltage (Vth1).

The voltage measuring unit 110 may apply the voltage at both ends of the IGBT to both input terminals (+) of the first comparator 121 and the second comparator 123, respectively.

The first comparator 121 may compare the voltage across the IGBT with the first threshold voltage (Vth1) and output a low trigger signal (Trig_LOW) as a result of the comparison. When the voltage across the IGBT is less than the first threshold voltage (Vth1), the first comparator 121 may output a low trigger signal (Trig_LOW) at a low level. The first comparator 121 may output a high level low trigger signal (Trig_LOW) when the voltage at both ends of the IGBT is greater than or equal to the first threshold voltage (Vth1). Here, the low level may be 0V and the high level may be 5V. The low trigger signal (Trig_LOW) may be transmitted to the control unit 130.

The second comparator 123 may compare the voltage across the IGBT with the second threshold voltage (Vth2) and output a high trigger signal (Trig_HIGH) as a result of the comparison. When the voltage at both ends of the IGBT is less than the second threshold voltage (Vth2), the second comparator 123 may output a low level high trigger signal (Trig_HIGH). The second comparator 123 may output a high trigger signal (Trig_HIGH) at a high level when the voltage at both ends of the IGBT is greater than or equal to the second threshold voltage (Vth2). The high trigger signal (Trig_HIGH) may be transmitted to the control unit 130.

The comparator 120 may calculate the rate of change per hour of the voltage at both ends of the IGBT according to the time at which the voltage level above the second threshold voltage (Vth2) is detected after the voltage level above the first threshold voltage (Vth1) is detected. At this time, when the time at which the voltage level above the second threshold voltage (Vth2) is detected is relatively short, the rate of change per hour appears large, and when the time at which the voltage level above the second threshold voltage (Vth2) is detected is relatively long, the rate of change per hour appears small. .

FIG. 3 is a diagram showing an example of the output value of the comparison unit of FIG. 2.

Referring to FIG. 3, three types of comparison results output from the comparison unit 120 can be confirmed.

In one embodiment, the first comparison result is a low trigger signal (Trig_LOW) in which a rising edge occurs at the trigger time (t_trig), and a high trigger signal (Trig_HIGH) in which a rising edge occurs in the section after the second reference time (t_NOR). ) may include.

In one embodiment, the second comparison result is a low trigger signal (Trig_LOW) in which a rising edge occurs at the trigger time (t_trig), and a rising edge in the section between the first reference time (t_HC) and the second reference time (t_NOR). It may include a high trigger signal (Trig_HIGH) that generates.

In one embodiment, the third comparison result is a low trigger signal (Trig_LOW) in which a rising edge occurs at the trigger time (t_trig), and a rising edge in the section between the first reference time (t_trig) and the second reference time (t_HC). It may include a high trigger signal (Trig_HIGH) that generates.

The trigger time (t_trig) can be defined as the time when the voltage at both ends of the IGBT reaches the first threshold voltage (Vth1). The first reference point (t_HC) can be defined as a point in time that has elapsed from the trigger point (t_trig). The second reference point (t_NOR) can be defined as a certain amount of time after the first reference point (t_HC). Here, the certain time may be 1ms, but is not limited thereto.

FIG. 4 is a diagram for explaining a method of selecting the resistance of an IGBT gate in the control unit of FIG. 1.

Referring to FIGS. 3 and 4 , a plurality of resistors that can be connected to the gate of the IGBT 200 may be prepared in advance. The plurality of resistors may include a first resistor (R_ON), a second resistor (R_NORMAL), a third resistor (R_HIGH_CURRENT), and a fourth resistor (R_OC/SC/DESAT).

The first resistor (R_ON) may be a resistor connected to the gate (GATE) when the IGBT (200) is turned on.

When the second resistor (R_NORMAL), third resistor (R_HIGH_CURRENT), or fourth resistor (R_OC/SC/DESAT) is selected by the control unit 130 when the IGBT is turned off, it acts as the gate (GATE) of the IGBT by relay control. can be connected to The second resistor (R_NORMAL), the third resistor (R_HIGH_CURRENT), and the fourth resistor (R_OC/SC/DESAT) may have different resistance values. The third resistor (R_HIGH_CURRENT) may have a higher resistance value than the second resistor (R_NORMAL). The fourth resistor (R_OC/SC/DESAT) may have a higher resistance value than the third resistor (R_HIGH_CURRENT).

The control unit 130 may be equipped with an ON control function and an OFF control function. When controlling the turn-on of the IGBT 200, the control unit 130 may apply a voltage to the gate of the IGBT 200 through the first resistor R_ON.

When controlling the turn-off of the IGBT 200, the control unit 130 may select one resistor from among a plurality of resistors using the low trigger signal and the high trigger signal received from the comparison unit 120.

The control unit 130 may have a timer function. The control unit 130 turns on the timer function to set the first reference time (t_HC) and the second reference time (t_NOR) after the trigger time (t_trig) when the voltage at both ends of the IGBT (200) reaches the first threshold voltage (Vth1). can be set. That is, the control unit 130 may set a point in time that has elapsed from the trigger point (t_trig) at which the rising edge of the low trigger signal occurs as the first reference point (t_HC). The control unit 130 may set a point in time that has elapsed from the first reference point in time (t_HC) as the second reference point in time (t_NOR). Here, the constant time may be 1ms.

The control unit 130 may determine the state of the IGBT by considering the signal level of the high trigger signal at various points in time, and select one resistor from among a plurality of resistors depending on the state of the IGBT. In one embodiment, when the rising edge of the high trigger signal occurs in a section past the second reference time point (t_NOR), the control unit 130 may determine a normal state and select the second resistance (R_NORMAL).

In one embodiment, when the rising edge of the high trigger signal occurs in the section between the first reference point (t_HC) and the second reference point, the control unit 130 determines the high current state and selects the third resistor (R_HIGH_CURRENT). You can.

In one embodiment, when the rising edge of the high trigger signal occurs in the section between the trigger time (t_trig) and the first reference time, the control unit 130 determines an overcurrent state and sets the fourth resistor (R_OC/SC/DESAT). You can select .

The control unit 130 may perform relay control so that the selected resistor is connected to the gate of the IGBT (200).

Figure 5 is a diagram showing an example of the voltage between the collector and emitter of an IGBT. Figure 5(a) shows an example of high current, and Figure 5(b) shows an example of low current.

Referring to FIG. 5, when the IGBT (200) is turned off, voltage oscillation occurs in proportion to the current (high current or low current) due to the inductance component of the motor connected to the IGBT (200). , a peak voltage (Vce_PEAK) is generated between the collector and emitter of the IGBT (200). This peak voltage (Vce_PEAK) is proportional to the slope of the rising voltage and may appear differently depending on the surrounding environment of the IGBT. Here, the current used may be high current (ex. 450A) or low current (ex. 225A).

Conventionally, the gate resistance value is set after preliminary testing of the IGBT and then installed in the actual product, but it is difficult to respond adaptively when the peak voltage changes depending on the surrounding environment.

To solve this problem, the control unit 130 can select the gate resistance value so that the peak voltage (Vce_PEAK) does not exceed the maximum allowable voltage of the IGBT.

That is, the control unit 130 recognizes the rate of change per hour (dv/dt) of the voltage at both ends of the IGBT according to the comparison result of the comparison unit 120 without a separate current sensor, and selects the gate resistance of the IGBT for each operation section to generate the peak voltage. It can be ensured that it does not exceed this maximum allowable voltage.

Figure 6 is a flowchart of an IGBT control method according to a preferred embodiment of the present invention.

1 and 6, the IGBT control method according to a preferred embodiment of the present invention may include a voltage measurement step (S610), a comparison step (S620), a selection step (S630), and a control step (S640). there is.

In the voltage measurement step (S610), the voltage measurement unit 110 measures the voltage (voltage at both ends) between the collector and emitter of the IGBT (200).

In the comparison step (S620), the comparison unit 120 calculates the rate of change per hour of the voltage at both ends of the IGBT (200). At this time, the comparison unit 120 may compare the voltage at both ends of the IGBT 200 with a plurality of preset threshold voltages. The plurality of threshold voltages include a first threshold voltage and a second threshold voltage higher than the first threshold voltage. The comparator 120 may compare the voltage at both ends of the IGBT 200 with the first threshold voltage and output a low trigger signal as a result of the comparison. The comparator 120 may compare the voltage at both ends of the IGBT 200 with the first threshold voltage and output a high trigger signal as a result of the comparison.

In the selection step (S630), the control unit 130 may select one resistor from among a plurality of resistors according to the time rate of change of the voltage across the IGBT. Here, the control unit 130 sets a time point after a certain time as the first reference time point (t_HC) based on the trigger time point at which the high-level low trigger signal is received, and sets a certain time point based on the first reference time point. The time point after time can be set as the second reference time point (t_NOR). The control unit 130 may determine the state of the IGBT by considering the trigger time point (t_trig), the first reference time point (t_HC), the second reference time point, and the rising edge of the high trigger signal. The control unit 130 may select one resistor from among a plurality of resistors by considering the result of determining the state of the IGBT.

In the control step (S640), the control unit 130 performs relay control so that the selected resistor is connected to the gate of the IGBT. Through this, the control unit 130 can prevent the peak voltage generated at the collector and emitter of the IGBT 200 from exceeding the maximum allowable voltage.

The above description is merely an illustrative explanation of the technical idea of the present invention, and various modifications, changes, and substitutions can be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the attached drawings are not intended to limit the technical idea of the present invention, but are for illustrative purposes, and the scope of the technical idea of the present invention is not limited by these embodiments and the attached drawings. .

Steps and/or operations according to the invention may occur simultaneously in different embodiments, in different orders, or in parallel, or for different epochs, etc., as would be understood by those skilled in the art. You can.

Depending on the embodiment, some or all of the steps and/or operations may include executing instructions, programs, interactive data structures, clients and/or servers stored on one or more non-transitory computer-readable media. At least a portion may be implemented or performed using one or more processors. The one or more non-transitory computer-readable media may illustratively be software, firmware, hardware, and/or any combination thereof. Additionally, the functionality of the “modules” discussed herein may be implemented in software, firmware, hardware, and/or any combination thereof.

100: IGBT control device
110: Voltage measurement unit
120: Comparison section
121, 123: first and second comparators
130: control unit

Claims (13)

A voltage measurement unit that measures the voltage at both ends of the IGBT when the IGBT is turned off;
a comparison unit that calculates a rate of change per hour of the voltage at both ends of the IGBT; and
a control unit that selects one resistor from among a plurality of resistors prepared in advance according to the calculation result of the comparison unit and controls a relay so that the selected resistor is connected to the gate of the IGBT;
IGBT control device including. According to claim 1,
The comparison unit,
An IGBT control device, characterized in that the voltage at both ends of the IGBT is compared with a plurality of preset threshold voltages. According to claim 2,
IGBT control device, characterized in that the plurality of threshold voltages include a first threshold voltage and a second threshold voltage higher than the first threshold voltage. According to claim 3,
The comparison section,
When the voltage at both ends of the IGBT is greater than or equal to the first threshold voltage, a high level low trigger signal is output, and when the voltage at both ends of the IGBT is greater than or equal to the second threshold voltage, a high level high trigger signal is output. IGBT control device. According to claim 4,
The control unit,
Characterized by setting a point in time at which a certain time has elapsed based on the trigger point in time at which the low trigger signal of high level is received as a first reference point in time, and setting a point in time at which a certain amount of time has elapsed from the first reference point in time as a second reference point in time. IGBT control device. According to claim 5,
The control unit,
When the rising edge of the high trigger signal occurs in a section past the second reference point, the IGBT control device determines a normal state and selects a second resistor from among the plurality of resistors. According to claim 5,
The control unit,
When a rising edge of the high trigger signal occurs in the section between the first reference point and the second reference point, the IGBT control device determines a high current state and selects a third resistor from among the plurality of resistors. According to claim 5,
The control unit,
When a rising edge of the high trigger signal occurs in the section between the trigger time and the first reference time, an IGBT control device determines an overcurrent state and selects a fourth resistor from among the plurality of resistors. According to claim 1,
IGBT control device, characterized in that the plurality of resistors have different resistance values. A voltage measurement step of measuring the voltage across the IGBT when the IGBT is turned off;
A comparison step of calculating the rate of change per hour of the voltage at both ends of the IGBT;
A selection step of selecting one resistor from among a plurality of resistors prepared in advance according to the calculation in the comparison step; and
A control step of controlling the relay so that the selected resistor is connected to the gate of the IGBT;
IGBT control method including. According to claim 10,
The comparison step is,
A first comparison step of comparing a voltage at both ends of the IGBT and a first threshold voltage to output a low trigger signal;
An IGBT control method comprising a second comparison step of comparing a voltage at both ends of the IGBT and a second threshold voltage to output a high trigger signal. According to claim 11,
The selection step is,
Setting a first reference time point after a certain time based on the trigger point when the voltage at both ends of the IGBT reaches the first threshold voltage, and a second reference time point after a certain time based on the first reference point. IGBT control method comprising a setting step. According to claim 12,
The selection step is,
The state of the IGBT is determined in consideration of the rising edges of the high trigger signal occurring at the trigger time, the first reference time, and the second reference time, and according to the determination result, any one resistor among a plurality of resistors is selected. IGBT control method characterized by selecting.

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