KR101259623B1 - Apparatus for controlling inverter current and Method for operating the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current control device of an inverter and a method of operating the same, and to a current control device and a current control method of controlling a current of a switching element of an inverter for outputting a three-phase alternating current and detecting an upper lock. Inverter current control device according to an embodiment of the present invention, the plurality of switching elements are turned on and off, respectively, the inverter to convert the input DC voltage into three-phase alternating current and output to the motor, the three-phase (three phase) phase of the same polarity A phase current of opposite polarity is calculated using a current detection sensor detecting a phase current flowing through a plurality of switching elements outputting a plurality of phases, and the phase current detected by the current detection sensor, and the measured phase currents of the same polarity and the calculated polarity of the opposite polarity are calculated. The controller may include a control unit configured to output a driving signal for controlling on / off of the plurality of switching elements with reference to a phase current.

Description

Apparatus for controlling inverter current and Method for operating the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a current control device of an inverter and a method of operating the same, and to a current control device and a current control method of controlling a current of a switching element of an inverter for outputting a three-phase alternating current and detecting an upper lock.

In a vehicle such as a hybrid car or an electric vehicle, a high voltage battery is used to drive a driving motor or a compressor motor, and a low voltage battery is used to communicate with an audio device or a local interconnect network (LIN) or controller area network (CAN). Drive a communication device to In such a configuration, for example, when the motor control unit for controlling the operation of the inverter device and the communication control unit for controlling the operation of the communication device transmit and receive signals with each other, the signal is transmitted and received through the photocoupler.

In general, an apparatus for driving a motor by controlling an inverter includes a high voltage battery 10, a voltage converter converting a voltage of the high voltage battery into another voltage, and the converted voltage. A smoothing unit 30 (filter capacitor) for storing and smoothing voltage, an inverter 40 for converting a DC voltage of the smoothing unit into an alternating voltage, and an AC voltage of the inverter And a control unit 50 for controlling the motor 60 and the output frequency.

The inverter 40 connects and uses a switching device, and generally uses a semiconductor device called an insulated gate bipolar transistor (IGBT) having excellent characteristics as a switching device.

When an output short circuit or an arm short circuit occurs in the inverter 40 and a short circuit current flows in the switching element IGBT, the short circuit current of the switching element is allowed by the gate-emitter voltage VGE applied to the switching element. The current rises and the collector-emitter voltage VCE of the switching element rises in proportion to the current. As described above, due to the short-circuit current, when an uncontrolled current (hereinafter, referred to as an 'accident current') flows in the IGBT element, which is a switching element in the inverter, it is necessary to take appropriate action.

To this end, conventionally, a separate detection for performing current control and short-circuit current detection using current values detected by phase output current detection sensors 70 (70a, 70a, 70b, 70c) installed in a phase ouptut for current control purposes. I had to put a dedicated circuit.

For example, in the normal case, when the switching element is turned on, the input voltage VCC is connected to GND through a pull-up resistor, current limiting resistor, blocking diode, switching element. At this time, only the turn-on voltage of the switching element is detected to perform normal operation. On the contrary, when the switching element is shorted, the turn-on voltage of the switching element rises in proportion to the magnitude of the short-circuit current, and compared with the reference voltage of the comparison unit to determine the presence or absence of a short circuit detection and transmit a failure signal to the control unit.

However, there is a problem in that an inverter control device having a detection-only circuit having a short-circuit detection function according to the prior art increases costs and cannot adjust the short-circuit detection level. In addition, when a phase short occurs due to the simultaneous conduction of a switching element that outputs a positive phase and a switching element that outputs a negative phase current, such a phase lock cannot be detected only by a phase output current detection sensor installed in the phase output stage. there is a problem.

An object of the present invention is to provide an inverter current control device and a current control method without a dedicated detection circuit having a short-circuit detection function. Another object of the present invention is to provide a method for measuring a current flowing through a switching device. In addition, the technical problem of the present invention is to detect the current flowing through the switching element to the minimum to perform the inverter current control.

Inverter current control device according to an embodiment of the present invention, the plurality of switching elements are turned on and off, respectively, the inverter to convert the input DC voltage into three-phase alternating current and output to the motor, the three-phase (three phase) phase of the same polarity A phase current of opposite polarity is calculated using a current detection sensor detecting a phase current flowing through a plurality of switching elements outputting a plurality of phases, and the phase current detected by the current detection sensor, and the measured phase currents of the same polarity and the calculated polarity of the opposite polarity are calculated. The controller may include a control unit configured to output a driving signal for controlling on / off of the plurality of switching elements with reference to a phase current.

Calculating the phase current of the opposite polarity by using the phase current detected by the current detection sensor, when the three phases of the same polarity of the first, second, third phase of the same polarity, The absolute value is calculated by adding the same polarity of the second phase and the third phase.

The controller warns that an upper lock has occurred when the sum of three-phase alternating current at a specific phase point is not '0' with reference to the measured phase current having the same polarity and the calculated phase current having the opposite polarity. The switching device is an insulated gate bipolar transistor (IGBT) device.

In addition, the inverter current control method according to an embodiment of the present invention, the process of detecting a current flowing through a plurality of switching elements for outputting a three-phase phase current of the same polarity, and the phase current detected through the current detection sensor Calculating a phase current of opposite polarity, and receiving feedback of the measured phase current of the same polarity and the calculated phase current of the opposite polarity, and controlling the on / off control of the plurality of switching elements.

According to the embodiment of the present invention, the circuit can be simplified by directly detecting the current of the switching element using a current detection sensor without an extra detection dedicated circuit. In addition, according to the embodiment of the present invention can reduce the cost by minimizing the current detection sensor. In addition, according to the embodiment of the present invention, it is possible to directly and accurately detect whether the switching element is abnormal.

1 is a view showing a device for driving a motor by controlling a conventional inverter.
2 is a diagram illustrating a short circuit current detection circuit of an inverter according to an exemplary embodiment of the present invention.
3 is a view showing a state in which the current detection sensor is provided in the IGBT according to an embodiment of the present invention.
4 is a diagram showing waveforms of three-phase current.
5 is a flowchart illustrating a method of detecting an abnormality of an inverter using only three current detection sensors in an inverter according to an embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Wherein like reference numerals refer to like elements throughout.

2 is a diagram illustrating a short circuit current detection circuit of an inverter according to an exemplary embodiment of the present invention.

Hereinafter, an embodiment using an IGBT (Insulated Gate Bipolar Transistor) element as a switching element of an inverter will be described below, but the present invention is not limited thereto. It will be apparent that the embodiments may be applied. That is, each switching element constituting the inverter is not limited to an IGBT such as a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) in which diodes are connected in parallel.

For reference, the IGBT can only take advantage of the MOSFET and Bipolar transistor. IGBTs can actually be seen as replacements for MOSFETs. Since the MOSFET is a device driven by one type of carrier (electron or hole), there is a limit in increasing the breakdown voltage or the amount of current. Because of this, IGBTs can compensate for these disadvantages of MOSFETs and achieve high breakdown voltages and currents. However, IGBT has the disadvantage of being slower than MOSFET. Briefly describing the features of the IGBT device, the IGBT has the same voltage control scheme as the MOSFET and has low ON-resistance, making it widely used in high power devices. Comparing the difference in voltage-dependent ON-resistance between the MOSFET and the IGBT, the conduction resistance in the IGBT is lower than in the MOSFET over a wide voltage range. Comparing the characteristics of switching devices IGBT, MOS FET and TR, the input type is controlled by voltage, IGBT and MOS FET by voltage, BJT by current, and input resistance is very high while IGBT and MOS FET are low, but BJT is low. . In addition, the operating frequency is medium IGBT, MOS FET is high, BJT is low, switching speed is medium, IGBT is medium, MOS FET is very fast and BJT is the slowest.

Referring to FIG. 2, a current control device for controlling an inverter to drive a motor includes a high voltage battery 500, a voltage converting unit 600 converting a voltage of the high voltage battery into another DC voltage, and the converted voltage. A smoothing unit 700 (filter capacitor) for storing and smoothing voltage, an inverter 100 for converting a DC voltage of the smoothing unit into an alternating voltage, a motor 300 driven by an alternating voltage of the inverter, and A control unit 200 for controlling the output frequency, and a drive circuit 400 for receiving the drive signal of the control unit for providing to the input gate (gate) of the switching element of the inverter. The inverter 100 controls the drive of the compressor motor mounted in a vehicle such as a hybrid vehicle or an electric vehicle, for example.

The drive circuit 400 outputs the respective drive signals output from the control unit to the gates of the IGBTs (Pu, Pv, Pw, Nu, Nv, and Nw), and outputs the IGBTs (Pu, Pv, Pw, Nu, Nv and Nw) are switched on and off, respectively.

The control unit 200 obtains the current position of the rotor of the motor 300 based on the three-phase currents Iu, Iv, and Iw, and inputs the current position of the rotor and the command message inputted from outside. The phase voltages of the U phase, V phase, and W phase are obtained based on the command message, and the switching elements (Pu, Pv, Pw, Each drive signal for controlling the on and off of Nu, Nv, and Nw) is generated. In addition, the control unit 200 transmits and receives a signal to and from a device that controls the operation of the communication device 24 that performs communication such as LIN and CAN.

In particular, the control unit 200 according to the embodiment of the present invention calculates a pattern of negative phase currents of opposite polarity using positive phase currents detected through the current detection sensors 110, 120, and 130, and calculates the measured positive phase currents and opposite polarities of the same polarity. The driving signal for controlling the on / off of the plurality of switching elements is output with reference to the negative phase current. An operation example of the control unit will be described in detail later.

The inverter 100 turns on and off a plurality of switching elements, respectively, and converts the input DC voltage into three-phase AC and outputs it to the motor. For example, the inverter 100 is connected to each other in series and outputs the n-channel first_IGBT (Pu) and the second_IGBT (Nu) and the n-channel third_IGBT (in series connected to each other and outputting the V phase ( Pv) and the fourth_IGBT (Nv) and the fifth channel_IGBT (Pw) and the sixth_IGBT (Nw) of the n-channel which are connected in series to each other and output the W phase are connected in parallel to the high voltage battery 500. The first_IGBT (Pu), the third_IGBT (Pv), and the fifth_IGBT (Pw) are switching devices which output three-phase currents of positive U, V, and W, respectively, and the second_IGBT (Nu), fourth_IGBT (Nv), The sixth_IGBT (Nw) is a switching device that outputs negative U, V, and W three-phase currents, respectively. For reference, in each IGBT (Pu, Pv, Pw, Nu, Nv, Nw), a diode D for blocking current is connected in parallel between the collector stage C and the emitter stage E.

The connection point node between the first _IGBT (Pu) and the second _IGBT (Nu) and the U phase of the motor 300 are connected, and the connection point node between the third third IGBT (Pv) and the fourth IGBT (Nv) and the V phase of the motor 300 are connected. And the connection point node of the fifth_IGBT (Pw) and the sixth_IGBT (Nw) and the W phase of the motor 300 are connected. When the IGBTs (Pu, Pv, Pw, Nu, Nv, and Nw) are sequentially turned on and off, a plurality of alternating currents flow through the motor 300 to rotate the rotor of the motor 300.

Each of the switching elements IGBTs (Pu, Pv, Pw, Nu, Nv, and Nw) is provided with current detection sensors 110 (110a, 110b, 110c, 110d, 110e, and 110f) for detecting a current flowing in each IGBT. As the current detection sensor 110, a low may be used. For example, a current detecting resistor is provided at an emitter end (E; emiter) of each IGBT element (Pu, Pv, Pw, Nu, Nv, Nw), and the voltage applied to each resistor is measured to measure voltage (V) and resistance ( The current can be detected through the relationship of R) and current I (V = RI). It will be apparent that various current detection sensors can be applied.

As described above, the current of the IGBT measured by the current detection sensor 110 provided in each of the IGBT elements Pu, Pv, Pw, Nu, Nv, and Nw is provided to the controller 200. The controller receives the current of the IGB through the current detection sensor 110 provided in each IGBT element as described above, and can quickly detect whether a short circuit current has occurred by comparing whether the current of the IGBT flows normally.

For example, when a short circuit current flows through the IGBT, the control unit directly detects a voltage applied to the current detection resistor (current detection sensor) connected to the emitter terminal E of the IGB element, and compares the voltage with a preset reference voltage in a separate comparison unit. The presence or absence of a fault signal can be transmitted as a short circuit detection signal.

For reference, when a current is detected through a current detection sensor included in each IGBT element, the detection current may be used for current control as well as the short circuit current detection described above.

On the other hand, an inverter having a function of directly detecting a short circuit current through the six current detection sensors included in each of the above-described IGBT elements requires a current detection sensor in each of the IGBT elements, which is relatively expensive. Can be a relatively complex problem.

To this end, the embodiment of the present invention detects and uses only a current flowing through a plurality of switching elements outputting a three-phase current phase of the same polarity.

When the same polarity is defined as a positive polarity and the opposite polarity is defined as a negative polarity, an embodiment of the present invention is a positive switching element as shown in FIG. 3 (a), that is, 1_IGBT (Pu) and 3_IGBT (Pv) ), Three current detection sensors 110a, 110b, and 110c are provided only in the fifth IGBT Pw to detect phase current.

In general, when three phase outputs of the current U in the phase I, the current I in the V phase and the current Iw in the W phase are normally output to the motor, they are output as shown in FIG. do. Through the three-phase output (Iu, Iv, Iw) having each of these phases, it can be seen that the sum of the three-phase output has a characteristic of being zero.

Iu + Iv + Iw = 0

The embodiment of the present invention utilizes the characteristics of the three phases so that the top lock (when the positive switching element and the negative switching element are simultaneously conducted) or the phase ground (phase output is GND) through only three current detection sensors. Connected).

FIG. 4 (a) is a circuit diagram illustrating three current detection sensors provided only in the first_IGBT (Pu), the third_IGBT (Pv), and the fifth_IGBT (Pw), which are positive switching elements. The sensor can detect the upper lock (when the positive switching element and the negative switching element are connected simultaneously), the upper ground lock (when the phase output is connected to GND), and the like.

As shown in FIG. 4 (a), when three current detection sensors are provided only in the first_IGBT (Pu), the third_IGBT (Pv), and the fifth_IGBT (Pw) which are positive switching elements, any one Some of the patterns of the negative phase can be inferred from the other two positive phases that are actually measured.

That is, when the three phases of the same polarity are the same polarity first, second, and third phases, the absolute value of the current phase of the opposite polarity of the first phase sums the same polarity of the second phase and the third phase to calculate a pattern. Can be.

For example, the current of the second _IGBT (Nu) cannot be detected because a current detection sensor for detecting a current flowing through the second _IGBT (Nu) that provides a negative U phase is not provided. The absolute value of the current can be inferred from the two other positive phases (positive V and W phases) that are actually measured. That is, as shown in Fig. 4B, in the T1 section, the absolute value of the current Iu_negative flowing in the second_IGBT (Nu) providing the negative U phase is transferred to the third_IGBT (Pv) providing the positive V phase. It is equal to the sum of the current flowing and the current flowing in the fifth_IGBT (Pw) providing the positive W phase. The controller may infer and calculate a part of the current pattern flowing in the second_IGBT (Nu) that provides the negative U-phase in the above manner.

The controller 200 may be used to control the on and off currents of the plurality of switch elements by using the negative current pattern inferred in the T1 section with reference to the actually measured positive current.

In addition, the control unit 200 refers to the positive current phase measured as the same polarity and the negative current phase calculated as the opposite polarity, and when the sum of the three-phase alternating currents at a specific phase point is not '0', an upper lock occurs. Occurs.

In addition, when the first_IGBT (Pu) and the second_IGBT (Nu) are simultaneously connected to each other and the normal positive U phase is not output and short-circuited, the controller 200 detects that an upper lock has occurred and generates an alarm. .

On the other hand, not the first (IG) (Pu), the third _IGBT (Pv), the fifth _IGBT (Pw), which is a positive switching device, but the second (IG) (Nu), the fourth _IGBT (Pv), the sixth IGBT (Negative) switching device Nw) only if three current detection sensors are provided as well.

In detail, FIG. 3 (b) shows three current detection sensors 110d, 110e, and 110f provided only in a second switching element, ie, 2_IGBT (Nu), 4_IGBT (Pv), and 6_IGBT (Nw). As a circuit diagram showing the above, only the three current detection sensors can detect the upper lock (when the positive switching element and the negative switching element are simultaneously conducted), the ground fault (when the phase output is connected to GND), and the like.

As shown in FIG. 3 (b), in the case where three current detection sensors are provided only in the second_IGBT (Nu), the fourth_IGBT (Pv), and the sixth_IGBT (Nw) which are negative switching elements, any one Part of the pattern of the positive phase can be inferred from the other two negative phases that are actually measured.

For example, the current of the first _IGBT (Pu) can not be detected because there is no current detection sensor for detecting the current flowing in the first _IGBT (Pu) providing a positive U-phase, the current of the first _IGBT (Pu) The absolute value can be inferred from the other two negative phases (negative V, W phases) that are actually measured. Likewise, through the inferred current pattern, it can be used for current control, and it can be determined whether the switching elements are operating normally.

5 is a flowchart illustrating a method of detecting an abnormality of an inverter using only three current detection sensors in an inverter according to an embodiment of the present invention.

First, a current flowing through each of the switching elements outputting a phase of the same polarity is detected.

First, a current flowing through a plurality of switching elements outputting a three-phase phase current of the same polarity is detected (S510).

That is, the current is detected only in the positive switching elements outputting the positive phase, or conversely, the current is detected only in the negative switching elements outputting the negative phase. If the positive switching element detects the current, the other negative switching element does not need to detect the current. On the contrary, if the current is detected in the negative switching element, it is not necessary to detect the current in the other positive switching element.

For example, as illustrated in FIG. 3A, only three current detection sensors are provided in only the first_IGBT (Pu), the third_IGBT (Pv), and the fifth_IGBT (Pw), which are positive switching elements, to detect the positive phase current. . On the contrary, as shown in FIG. 3 (b), the second_IGBT (Nu), which is a negative switching element, is not the first_IGBT (Pu), the third_IGBT (Pv), and the fifth_IGBT (Pw), which are positive switching elements. Only the fourth_IGBT (Pv) and the sixth_IGBT (Nw) may include three current detection sensors to detect the negative phase current.

For reference, detecting the current of the switching element is detected by using a current detection sensor that detects a current flowing in the emitter end (E; emiter) of the IGBT element. As the current detection sensor, a resistor can be used. That is, a current detection resistor is provided at an emitter end (E; emitter) of each IGBT element, and the voltage applied to each resistor is measured, and the relationship between voltage (V) and resistance (R) and current (I) (V = RI Current can be detected. In addition, it will be apparent that various current detection sensors other than resistors may be applied.

After detecting the current (S510) for the switching elements that output the phase of the same polarity as described above, the phase pattern of the opposite polarity is calculated (S520).

As shown in FIG. 3 (a), when the positive phase current is detected by providing three current detection sensors only in the first_IGBT (Pu), the third_IGBT (Pv), and the fifth_IGBT (Pw), which are positive switching elements, Using these positive phase currents, a pattern of negative phase currents is calculated.

For example, the absolute value of the current flowing in the second_IGBT (Nu) that provides a negative U phase can be inferred through two other positive phases (positive V, W phases) with different polarities that are actually measured. That is, as shown in Fig. 4B, in the T1 section, the absolute value of the current Iu_negative flowing in the second_IGBT (Nu) providing the negative U phase is transferred to the third_IGBT (Pv) providing the positive V phase. It is equal to the sum of the current Iv flowing and the current Iw flowing in the fifth IGBT Pw providing the positive W phase. The control unit calculates a part of the current pattern flowing in the second_IGBT Nu which provides the negative U phase in the above manner.

By using the negative current pattern inferred in the T1 section as described above, it may be used for current control together with the actually measured positive current (S520).

That is, the calculated negative current pattern may be used to control the on / off current of the plurality of switch elements with reference to the positive current to be measured.

In addition, with reference to the negative current phase calculated as the opposite polarity and the positive current phase measured as the same polarity, an alarm may be generated that an upper lock has occurred when the sum of three-phase alternating currents at a specific phase point is not '0'.

In addition, when the first_IGBT (Pu) and the second_IGBT (Nu) are simultaneously connected to each other so that a normal positive U phase is not output and is short-circuited and not normally output, the controller may detect that an upper lock has occurred.

Although the present invention has been described with reference to the accompanying drawings and the preferred embodiments described above, the present invention is not limited thereto but is limited by the following claims. Accordingly, those skilled in the art will appreciate that various modifications and changes may be made thereto without departing from the spirit of the following claims.

100: inverter 110: current detection sensor
200: control unit 300: motor
Pu, Pv, Pw: positive phase current generating switching element
Nu, Nv, Nw: Negative phase current generating switching device

Claims (11)

A plurality of switching elements are turned on and off, respectively, thereby converting an input DC voltage into three-phase AC and outputting the same to a motor;
A current detection sensor for detecting a phase current flowing through a plurality of switching elements outputting three-phase phase currents of the same polarity;
The phase current of the opposite polarity is calculated using the phase current detected by the current detection sensor, and the driving signal for controlling the on / off control of the plurality of switching elements by referring to the measured phase current of the same polarity and the calculated phase current of the opposite polarity. A control unit for outputting the upper phase, when the sum of three-phase alternating current at a specific phase point is not '0', with reference to the measured phase current having the same polarity and the calculated phase current having the opposite polarity;
Current control device of the inverter comprising a. The method of claim 1, wherein the phase current having the opposite polarity is calculated using the phase current detected by the current detection sensor.
When the three phases of the same polarity are the same polarity of the first, second, and third phases, the current control of the inverter in which the absolute value of the phase current of the opposite polarity of the first phase is calculated by adding the same polarity of the second phase and the third phase. Device. delete The apparatus of claim 1, wherein the switching element is an insulated gate bipolar transistor (IGBT) element. The current control device of the inverter according to claim 4, wherein the current detection sensor detects a current flowing in the emitter end (E) of the IGBT. The apparatus of claim 1, wherein the current detection sensor detects a current flowing through a switching element outputting a phase of positive polarity. The apparatus of claim 1, wherein the current detection sensor detects a current flowing through a switching element outputting a phase of negative polarity. Detecting a current flowing through a plurality of switching elements outputting three-phase phase currents of the same polarity;
Calculating a phase current of opposite polarity using the detected phase current;
Controlling the plurality of switching elements on and off by receiving feedback of the measured phase current having the same polarity and the calculated phase current having the opposite polarity;
Alarming that an upper lock has occurred when the sum of three-phase alternating current at a specific phase point is not '0' with reference to the measured phase current having the same polarity and the calculated phase current having the opposite polarity;
Current control method of the inverter comprising a. The method according to claim 8, wherein when the switching element is an IGBT, the current control method of the inverter for detecting a current flowing in the emitter terminal (E) of the IGBT. The method of claim 8, wherein the calculating of the phase current of the opposite polarity is performed when the three phases of the same polarity are the first, second, and third phases of the same polarity. Inverter current control method for calculating the sum of the same polarity of the phase and the third phase. delete

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