Inverter control device and method

Abstract

The present invention discloses an inverter control device and method. The method of one embodiment of the present invention receives an inverter operation command, outputs a first PWM control signal to the inverter unit, so that the inverter unit outputs at least one of a plurality of effective vectors for diagnosing a short circuit of the output of the inverter, and blocks the output of the inverter when a short circuit current of the inverter unit is detected.

Description

Technical Field

[0001] The invention relates to an inverter control device and method. Background Art

[0002] Generally speaking, an inverter is a reverse conversion device that converts direct current (DC) electricity into alternating current (AC). Inverters used in industry are defined as a series of devices that receive power supplied from a commercial power source, autonomously change the voltage and frequency, and supply it to the motor, thereby controlling the motor speed in a manner that efficiently utilizes the motor speed. This inverter is controlled by a variable voltage variable frequency (VVVF) method, and can change the voltage and frequency input to the motor according to the pulse width modulation (PWM) output.

[0003] Figure 1 This is a diagram of the general inverter structure.

[0004] Generally speaking, the inverter 100 receives a three-phase AC power supply from the power supply unit 200, the rectifier unit 110 rectifies the three-phase AC power supply, and the smoother unit 120 smoothes and stores the DC voltage rectified by the rectifier unit 110. The inverter unit 130 outputs the DC voltage stored in the DC link capacitor as the smoother unit 120 as an AC voltage having a predetermined voltage and frequency according to a PWM control signal, and supplies the AC voltage to the motor 300.

[0005] At this time, the inverter unit 130 of the inverter 100 is composed of three-phase legs, and each leg is formed by connecting two switching elements in series.

[0006] A short circuit of the inverter 100 is a situation in which two or more phases in the output of the inverter 100 are short-circuited to each other and a very large short-circuit current flows into the interior of the inverter 100. This occurs when the coating of the output line of the inverter 100 deteriorates and peels off, or when the coating inside the motor 300 deteriorates and peels off, or when an operator makes an operational error.

[0007] When the inverter 100 is short-circuited, the current flowing into the inverter 100 reaches several times or more of the rated value, so the inverter 100 may be damaged, and even a personal accident may occur.

[0008] Therefore, the inverter 100 driving the motor 300 provides a function of notifying a user when an output short circuit occurs and safely protecting the motor 300 and the user by stopping the operation of the inverter 100 .

[0009] However, such a short-circuit detection circuit has a hardware circuit delay period, and when the magnitude of the effective vector is small, there is a problem that an output short-circuit cannot be detected due to the delay. Summary of the invention

[0010] Problems to be solved by the invention

[0011] The technical problem to be solved by the present invention is to provide an inverter control device and method for diagnosing a short circuit before the inverter is operated to stably drive the inverter.

[0012] Technical solutions to problems

[0013] In order to solve the technical problems described above, according to one embodiment of the present invention, a device for controlling an inverter may include: an inverter unit, which is composed of a plurality of switching elements, and converts a DC voltage into an AC voltage and outputs it under the control of a control unit; a short-circuit detection unit, which detects a short-circuit current flowing in the inverter unit; and the control unit, which applies a pulse width modulation (PWM) control signal to the inverter unit, so that the inverter unit outputs at least one of a plurality of valid vectors for diagnosing a short circuit of the output of the inverter.

[0014] In one embodiment of the present invention, the inverter unit is composed of three-phase legs that output a three-phase AC voltage, and the short-circuit detection unit can detect a short-circuit current flowing into a lower leg of the three-phase legs.

[0015] In an embodiment of the present invention, the PWM control signal may include a signal causing the inverter unit to output any one of [1 0 0], [0 1 0], [0 1 1], and [1 0 1] as the effective vector in response to a short circuit of the UV phases.

[0016] In an embodiment of the present invention, the PWM control signal may include a signal for causing the inverter unit to output one or more of [1 1 0], [0 1 0], [0 0 1], and [1 0 1] as the effective vector in response to a short circuit of the VW phase.

[0017] In an embodiment of the present invention, the PWM control signal may include a signal for causing the inverter unit to output one or more of [1 0 0], [1 1 0], [0 1 1], and [0 0 1] as the effective vector in response to a short circuit of the WU phase.

[0018] In an embodiment of the present invention, the control unit may output the PWM control signal so that the inverter unit can output at least one of the plurality of effective vectors for more than a predetermined time.

[0019] In one embodiment of the present invention, the predetermined time may be determined by circuit characteristics of the short-circuit detection unit.

[0020] In addition, in order to solve the technical problems mentioned above, according to one embodiment of the present invention, a method for controlling an inverter is provided, wherein the inverter includes an inverter unit composed of a plurality of switching elements and converts a DC voltage into an AC voltage and outputs it, wherein the control method may include: a step of receiving an operation instruction of the inverter; a step of outputting a first PWM control signal to the inverter unit so that the inverter unit outputs at least one of a plurality of valid vectors for diagnosing a short circuit of the output of the inverter; and a step of blocking the output of the inverter when a short-circuit current of the inverter unit is detected.

[0021] In an embodiment of the present invention, the first PWM control signal may include a signal causing the inverter unit to output any one of [1 0 0], [0 1 0], [0 1 1], and [1 0 1] as the effective vector in response to a short circuit of the UV phases.

[0022] In an embodiment of the present invention, the first PWM control signal may include one or more signals of [1 1 0], [0 1 0], [0 0 1], and [1 0 1] that cause the inverter unit to output the effective vector in response to a short circuit of the VW phase.

[0023] In an embodiment of the present invention, the first PWM control signal may include one or more signals of [1 0 0], [1 1 0], [0 1 1], and [0 0 1] that cause the inverter unit to output the effective vector in response to a short circuit of the WU phase.

[0024] In an embodiment of the present invention, the first PWM control signal may cause the inverter unit to output at least one of the plurality of effective vectors for a predetermined time or longer.

[0025] In one embodiment of the present invention, the predetermined time may be determined by circuit characteristics of a short-circuit detection unit that detects a short-circuit current.

[0026] The method according to an embodiment of the present invention may further include the step of outputting a second PWM control signal for normal operation of the inverter when a short-circuit current of the inverter unit is not detected.

[0027] Effects of the Invention

[0028] In the present invention as described above, if the inverter receives an operation command when a short circuit occurs, short circuit diagnosis is performed by diagnosing the PWM control signal and the output of the inverter is cut off in advance, thereby protecting the inverter and the operator. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 This is a diagram of the general inverter structure.

[0030] Figure 2 This is a diagram showing a current path when the U-phase and the V-phase are short-circuited in the inverter output.

[0031] Figure 3 This is a diagram showing a current path when the U-phase and the W-phase are short-circuited in the inverter output.

[0032] Figure 4 This is a diagram showing a current path when the V-phase and the W-phase are short-circuited in the inverter output.

[0033] Figure 5 This is an example diagram used to illustrate the spatial vector pulsewidth modulation (SVPWM) method of the inverter.

[0034] Figure 6 Yes means Figure 5 An example diagram of valid vectors in sector 1 of FIG.

[0035] Figure 7 FIG. 2 is a diagram showing an example of a current path when the output of the UV phase in sector 1 is short-circuited.

[0036] Figure 8 FIG. 2 is a diagram showing an example of a current path when the output of the VW phase in sector 1 is short-circuited.

[0037] Fig. 9 FIG. 1 is a diagram showing an example of a current path when the output of the WU phase in sector 1 is short-circuited.

[0038] Fig.10 FIG. 2 is a diagram showing an example of a current path when the output of the UV phase in sector 2 is short-circuited.

[0039] Fig.11 1 is a diagram for explaining an example of a current path when the outputs of the V-phase and the W-phase in the sector 2 are short-circuited.

[0040] Fig.12 FIG. 2 is a diagram showing an example of a current path when the output of the WU phase in sector 2 is short-circuited.

[0041] Fig.13FIG. 4 is a diagram showing an example of a current path when the output of the UV phase in sector 3 is short-circuited.

[0042] Fig.14 FIG. 2 is a diagram showing an example of a current path when the output of the VW phase in the sector 3 is short-circuited.

[0043] Fig.15 FIG. 2 is a diagram showing an example of a current path when the output of the WU phase in sector 3 is short-circuited.

[0044] Fig.16 FIG. 4 is a diagram showing an example of a current path when the output of the UV phase is short-circuited in sector 4 .

[0045] Fig.17 FIG. 4 is a diagram showing an example of a current path when the output of the VW phase in the sector 4 is short-circuited.

[0046] Fig.18 FIG. 4 is a diagram showing an example of a current path when the output of the WU phase in the sector 4 is short-circuited.

[0047] Fig.19 1 is a diagram showing an example of a current path when the output of the UV phase is short-circuited in the sector 5 .

[0048] Fig. 20 FIG. 2 is a diagram showing an example of a current path when the output of the VW phase in the sector 5 is short-circuited.

[0049] Fig.21 FIG. 2 is a diagram showing an example of a current path when the output of the WU phase in the sector 5 is short-circuited.

[0050] Fig. 22 FIG. 4 is a diagram showing an example of a current path when the output of the UV phase in the sector 6 is short-circuited.

[0051] Fig.23 FIG. 2 is a diagram showing an example of a current path when the output of the VW phase in the sector 6 is short-circuited.

[0052] Fig.24 FIG. 2 is a diagram showing an example of a current path when the output of the WU phase in the sector 6 is short-circuited.

[0053] Fig.25 This is an example diagram for explaining that short circuit detection cannot be performed when the effective vector [1 0 0] section is formed short.

[0054] Fig.26 This is a diagram for explaining an example of a section in which a short-circuit current cannot be detected when a UV phase output short-circuit occurs.

[0055] Fig. 27FIG. 1 is a diagram showing a structure of an inverter system according to an embodiment of the present invention.

[0056] Fig.28 It is an exemplary diagram for explaining a control method according to an embodiment of the present invention.

[0057] Fig.29 This is a diagram showing how a short-circuit current flows through each effective vector when the UV phase is short-circuited.

[0058] Fig.30 This is a diagram showing how a short-circuit current flows through each effective vector when the VW phase is short-circuited.

[0059] Fig.31 This is a diagram showing how a short-circuit current flows through each effective vector when the WU phase is short-circuited. DETAILED DESCRIPTION

[0060] In order to fully understand the composition and effect of the present invention, the preferred embodiments of the present invention are described with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be implemented in various forms and can be variously modified. However, the description of this embodiment makes the disclosure of the present invention complete and is provided to fully inform the ordinary technicians in the field to which the present invention belongs. In the accompanying drawings, for the convenience of description, the size of the constituent elements is enlarged more than the actual size, and the proportions of each constituent element may be enlarged or reduced.

[0061] In order to explain various constituent elements, terms such as "first", "second", etc. may be used, but such constituent elements are not limited to such terms. Such terms are only intended to distinguish one constituent element from another constituent element. For example, without departing from the scope of rights of the present invention, the "first constituent element" may be named as the "second constituent element", and similarly, the "second constituent element" may also be named as the "first constituent element". In addition, unless the context clearly indicates otherwise, a singular expression includes a plural expression. Unless otherwise defined, the terms used in the embodiments of the present invention may be interpreted as meanings known to those of ordinary skill in the art.

[0062] Hereinafter, referring to the accompanying drawings, a conventional inverter output short-circuit method is described, and an inverter control device according to an embodiment of the present invention is described.

[0063] Figure 2 This is a diagram showing the current path when the U-phase and V-phase are short-circuited in the inverter output. Figure 3 This is a diagram showing the current path when the U-phase and W-phase are short-circuited in the inverter output. Figure 4 This is a diagram showing a current path when the V-phase and the W-phase are short-circuited in the inverter output.

[0064] That is, Figures 2 to 4 As shown, the inverter output "short circuit" means that a "short circuit current" flows, which means a condition in which the upper and lower switches of the inverter part 130 are turned on together.

[0065] Figure 5 This is an example diagram for explaining the spatial vector pulsewidth modulation (SVPWM) method of the inverter. Figure 6 Yes means Figure 5 An example diagram of valid vectors in sector 1 of FIG.

[0066] in addition, Figure 7 2 is an example diagram for explaining a current path when the outputs of the U-phase and the V-phase in the sector 1 are short-circuited. Figure 8 1 is an example diagram for explaining a current path when the outputs of the V-phase and the W-phase in the sector 1 are short-circuited. Fig. 9 1 is a diagram for explaining an example of a current path when the outputs of the W-phase and the U-phase in the sector 1 are short-circuited.

[0067] Generally, SVPWM performs modulation using two effective vectors adjacent to a command voltage and a zero voltage in a manner of being averaged and synthesized within one cycle. Figure 5 The shaded part is sector 1 (5A), and the valid vectors in sector 1 (5A) are [1 0 0] and [1 1 0].

[0068] As described above, when the output of phase U and phase V is short-circuited in sector 1 (5A), the short-circuit current flows in the effective vector [10 0], and the current path at this time is as follows: Figure 7 At this time, when the effective vector is [1 1 0], the current is as follows: Figure 7 In this case, since there is no potential difference, no short-circuit current flows. That is, in the case of output short circuit between the U-phase and the V-phase in sector 1, the short-circuit current flows only when the effective vector is [1 0 0].

[0069] On the other hand, when the output of phase V and phase W is short-circuited in sector 1 (5A), the short-circuit current flows in the effective vector [11 0], and the current path at this time is as follows: Figure 8 As shown in (b). When the effective vector is [1 0 0], Figure 8 As shown in (a), there is no short-circuit current flow. That is, when the output of the V phase and the W phase in sector 1 is short-circuited, the short-circuit current flows only when the effective vector is [1 1 0].

[0070] In addition, when the output of phase W and phase U is short-circuited in sector 1 (5A), the short-circuit current flows in both the effective vectors [1 00] and [1 1 0]. The current paths at this time are as follows: Fig. 9 That is, when the output of the W phase and the U phase in sector 1 is short-circuited, the short-circuit current flows in both the effective vectors [1 0 0] and [1 1 0].

[0071] Similarly, in Figure 5 In sector 2 (5B), the valid vectors are [1 1 0] and [0 1 0].

[0072] Fig.10 2 is an example diagram for explaining a current path when the outputs of the U-phase and the V-phase in the sector 2 are short-circuited. Fig.11 2 is an example diagram for explaining a current path when the outputs of the V-phase and the W-phase in the sector 2 are short-circuited. Fig.12 1 is a diagram for explaining an example of a current path when the outputs of the W-phase and the U-phase in the sector 2 are short-circuited.

[0073] like Fig.10 As shown, in the case where the output of the U phase and the V phase is short-circuited in the sector 2 (5B), the short-circuit current flows in the effective vector [0 1 0] (refer to Fig.10 In the effective vector [1 1 0], there is no potential difference, so no short-circuit current flows (refer to Fig.10 (a)).

[0074] like Fig.11 As shown, in the case where the outputs of the V-phase and the W-phase are short-circuited in sector 2 (5B), the short-circuit current flows in both the effective vectors [1 1 0] and [0 1 0].

[0075] In addition, if Fig.12 As shown, in the case where the output of the W phase and the U phase is short-circuited in sector 2 (5B), the short-circuit current flows in the effective vector [1 1 0] (refer to Fig.12 (a)), there is no short-circuit current flow in the effective vector [0 1 0] (refer to Fig.12 (b)).

[0076] exist Figure 5 In sector 3 (5C), the valid vectors are [0 1 0] and [0 1 1].

[0077] Fig.13 2 is an example diagram for explaining a current path when the outputs of the U-phase and the V-phase in the sector 3 are short-circuited. Fig.14 2 is an example diagram for explaining a current path when the outputs of the V-phase and the W-phase in the sector 3 are short-circuited. Fig.151 is a diagram for explaining an example of a current path when the outputs of the W-phase and the U-phase in the sector 3 are short-circuited.

[0078] like Fig.13 As shown in FIG. 5 , when the output of the U phase and the V phase is short-circuited in sector 3 (5C), the short-circuit current flows in the effective vector [0 1 0] (refer to Fig.13 (a)), the short-circuit current also flows in the effective vector [0 1 1] (refer to Fig.13 (b)).

[0079] like Fig.14 As shown in FIG. 1 , when the output of the V phase and the W phase is short-circuited in sector 3 (5C), the short-circuit current flows in the effective vector [0 1 0] (refer to Fig.14 (a)), in the effective vector [0 1 1], there is no potential difference, so no short-circuit current flows (refer to Fig.14 (b)).

[0080] In addition, if Fig.15 As shown in FIG. 1 , when the output of the W phase and the U phase is short-circuited in sector 3 (5C), the short-circuit current flows in the effective vector [0 1 1] (refer to Fig.15 (b)), there is no short-circuit current flow in the effective vector [0 1 0] (refer to Fig.15 (a)).

[0081] exist Figure 5 In sector 4 (5D), the valid vectors are [0 1 1] and [0 0 1].

[0082] Fig.16 4 is an example diagram for explaining a current path when the outputs of the U-phase and the V-phase in the sector 4 are short-circuited. Fig.17 4 is an example diagram for explaining a current path when the outputs of the V-phase and the W-phase in the sector 4 are short-circuited. Fig.18 1 is a diagram for explaining an example of a current path when the outputs of the W-phase and the U-phase in the sector 4 are short-circuited.

[0083] like Fig.16 As shown, in the case where the output of the U phase and the V phase is short-circuited in sector 4 (5D), the short-circuit current flows in the effective vector [0 1 1] (refer to Fig.16 (a)), there is no short-circuit current flow in the effective vector [0 0 1] (refer to Fig.16 (b)).

[0084] like Fig.17 As shown, in the case where the outputs of the V phase and the W phase are short-circuited in sector 4 (5D), there is no potential difference in the effective vector [0 1 1], so no short-circuit current flows (refer to Fig.17(a)), the short-circuit current flows in the effective vector [0 01] (refer to Fig.17 (b)).

[0085] In addition, if Fig.18 As shown, in the case where the output of the W phase and the U phase is short-circuited in sector 4 (5D), the short-circuit current flows in the effective vector [0 1 1] (refer to Fig.18 (a)), the short-circuit current also flows in the effective vector [0 0 1] (refer to Fig.18 (b)).

[0086] exist Figure 5 In sector 5 (5E), the valid vectors are [0 0 1] and [1 0 1].

[0087] Fig.19 2 is an example diagram for explaining a current path when the outputs of the U-phase and the V-phase in the sector 5 are short-circuited. Fig. 20 2 is an example diagram for explaining a current path when the outputs of the V-phase and the W-phase in the sector 5 are short-circuited. Fig.21 1 is a diagram for explaining an example of a current path when the outputs of the W-phase and the U-phase in the sector 5 are short-circuited.

[0088] like Fig.19 As shown in FIG. 1 , when the output of the U phase and the V phase in the sector 5 (5E) is short-circuited, there is no short-circuit current flow in the effective vector [0 0 1] (refer to FIG. 1 ). Fig.19 (a)), the short-circuit current flows in the effective vector [1 0 1] (refer to Fig.19 (b)).

[0089] like Fig. 20 As shown in FIG. 1 , when the output of the V phase and the W phase is short-circuited in sector 5 (5E), the short-circuit current flows in the effective vector [0 0 1] (refer to FIG. 1 ). Fig. 20 (a)), the short-circuit current also flows in the effective vector [1 0 1] (refer to Fig. 20 (b)).

[0090] In addition, if Fig.21 As shown in FIG. 1 , when the output of the W phase and the U phase in the sector 5 (5E) is short-circuited, the short-circuit current flows in the effective vector [0 0 1] (refer to FIG. 1 ). Fig.21 In the effective vector [1 0 1], there is no potential difference, so no short-circuit current flows (refer to Fig.21 (b)).

[0091] exist Figure 5 In sector 6 (5F), the valid vectors are [1 0 1] and [1 0 0].

[0092] Fig. 22 2 is an example diagram for explaining a current path when the outputs of the U-phase and the V-phase in the sector 6 are short-circuited. Fig.23 2 is an example diagram for explaining a current path when the outputs of the V-phase and the W-phase in the sector 6 are short-circuited. Fig.24 1 is a diagram for explaining an example of a current path when the outputs of the W-phase and the U-phase in the sector 6 are short-circuited.

[0093] like Fig. 22 As shown in FIG. 1 , when the output of the U phase and the V phase is short-circuited in sector 6 (5F), the short-circuit current flows in both the effective vectors [1 0 1] and [1 0 0] (refer to FIG. 1 ). Fig. 22 (a) and (b)).

[0094] like Fig.23 As shown, in the case of a short circuit between the V-phase and the W-phase output in sector 6 (5F), the short circuit current flows in the effective vector [1 0 1] (refer to Fig.23 (a)), there is no short-circuit current flow in the effective vector [1 0 0] (refer to Fig.23 (b)).

[0095] In addition, if Fig.24 As shown, in the case where the output of the W phase and the U phase is short-circuited in sector 6 (5F), there is no potential difference in the effective vector [10 1], so no short-circuit current flows (refer to Fig.24 (a)), the short-circuit current flows in the effective vector [1 0 0] (refer to Fig.24 (b)).

[0096] As described above, when the U phase and the V phase are short-circuited, the short-circuit current flows in the effective vectors [1 0 0], [0 1 0], [0 1 1], and [1 0 1]. In addition, when the V phase and the W phase are short-circuited, the short-circuit current flows in the effective vectors [1 1 0], [0 1 0], [0 0 1], and [1 0 1]. In addition, when the W phase and the V phase are short-circuited, the short-circuit current flows in the effective vectors [1 0 0], [1 1 0], [0 1 1], and [0 0 1].

[0097] According to the existing short-circuit detection method, when a short circuit occurs, the short-circuit current flowing in the effective vector is detected to block the output of the inverter and notify the occurrence of a fault, thereby protecting the inverter and protecting the operator.

[0098] That is, in the conventional inverter output short-circuit detection method, when a short circuit occurs, a current path is formed in the section where the effective vector is applied, so the short-circuit current can be detected in the short-circuit detection circuit. However, there is a hardware delay time in the short-circuit detection circuit, so the short-circuit current cannot be accurately detected due to the delay time.

[0099] Fig.25 This is an example diagram for explaining that short circuit detection cannot be performed when the effective vector [1 0 0] section is formed short.

[0100] There is a circuit delay time in the short-circuit detection circuit. Therefore, in the low-speed operation interval of the inverter formed by a shorter effective vector [1 0 0] interval, the size of the effective vector is the same as the time to form the short-circuit path. Therefore, as the size of the effective vector decreases, there is a problem that the short-circuit detection circuit cannot detect it due to delay.

[0101] Fig.26 This is a diagram for explaining that when a UV phase output short circuit occurs, the magnitude of the effective vector is small (1.8 us) due to the low-speed operation of the inverter, and a section in which the short-circuit current cannot be detected.

[0102] As described above, in the existing short-circuit current detection circuit, the time that the hardware can detect is limited, so it is impossible to detect short-time short-circuit current. When this undetectable interval is repeated and continuous, there is a problem that the instantaneous short-circuit current continues to accumulate in the inverter and damages the inverter.

[0103] The present invention is used to solve the above-mentioned problem, and prevents the inverter from being damaged by diagnosing a short circuit before the inverter is operated, thereby detecting an output short circuit of the inverter in advance.

[0104] Fig. 27 FIG. 1 is a diagram showing a structure of an inverter system according to an embodiment of the present invention.

[0105] As shown in the figure, the inverter system of an embodiment of the present invention may include: an inverter 1; a motor 2 driven by the output of the inverter 1; and a control unit 3 for controlling the inverter 1. In addition, the system of an embodiment of the present invention may also include a display unit 4 and a communication unit 5. In addition, the system of an embodiment of the present invention may also include a short circuit detection unit 6.

[0106] The inverter 1 may include: a rectifying unit 11 for rectifying an input three-phase power supply; a smoothing unit 12 for smoothing a DC voltage rectified by the rectifying unit 11; and an inverter 13 for converting the DC voltage stored in the smoothing unit 12 into a three-phase AC voltage under the control of the control unit 3.

[0107] The inverter unit 13 is composed of a plurality of switching elements arranged in a predetermined topology, and can output single-phase AC voltages output from three legs to the motor 2 .

[0108] The control unit 3 may output a pulse width control (PWM) control signal to the inverter unit 13 so as to convert the DC voltage stored in the smoothing unit 12 into an AC voltage according to a predetermined command voltage.

[0109] In the stopped state of the inverter 1, since the PWM control signal of the control unit 3 is not applied, even if a short circuit is formed, it seems normal because no short circuit path is formed. However, if a PWM control signal is applied from the control unit 3 to the inverter 1 according to the operation command, a short circuit path is formed, and the inverter 1 may be damaged while the short circuit current flows.

[0110] Therefore, when the inverter 1 receives an operation command, the control unit 3 of the present invention performs preliminary diagnosis by applying a diagnostic PWM control signal for diagnosing a short circuit before applying the operation PWM control signal to the inverter unit 13. If a short circuit is detected, the output of the inverter 1 is blocked and the fault information is notified to the upper control system (not shown) through the communication unit 5, or information notifying the occurrence of the fault can be displayed on the display unit 4 so that the operator can visually confirm it.

[0111] In addition, if a short circuit is not detected, the control unit 3 may apply a normal PWM control signal to the inverter unit 13 of the inverter 1 to start a normal operation.

[0112] At this time, the short circuit detection unit 6 can detect the short circuit current flowing in the lower leg of the inverter unit 13 and provide the detection to the control unit 3. For example, the short circuit detection unit 6 may include a current transformer (CT), but the present invention is not limited thereto.

[0113] Fig.28 It is an exemplary diagram for explaining a control method according to an embodiment of the present invention.

[0114] As shown in the figure, the control unit 3 according to an embodiment of the present invention does not operate before receiving an operation command. When receiving an operation command ( S10 ), the control unit 3 may apply a diagnostic PWM control signal before applying a normal PWM control signal ( S15 ).

[0115] The diagnostic PWM control signal can be a PWM control signal that causes the inverter unit 13 to output any one of the effective vectors [1 0 0], [0 1 0], [0 1 1] and [1 0 1] in response to a short circuit of the UV phase; it can be a signal that causes the inverter unit 13 to output one or more of the effective vectors [1 1 0], [0 1 0], [0 0 1] and [1 0 1] in response to a short circuit of the VW phase; and it can be a signal that causes the inverter unit 13 to output one or more of the effective vectors [1 0 0], [1 1 0], [0 1 1] and [0 0 1] in response to a short circuit of the WU phase.

[0116] First, the control unit 3 can determine whether the U-phase and the V-phase are short-circuited by applying a PWM control signal that causes the inverter unit 13 to output any one of the effective vectors [1 0 0], [0 1 0], [0 11], and [1 0 1]. Fig.29 This is a diagram showing how a short-circuit current flows through each effective vector when the UV phase is short-circuited.

[0117] That is, Fig.29 As shown, the control unit 3 applies a PWM control signal that causes one of the above-mentioned effective vectors to be output. When the short-circuit detection unit 6 detects the current flowing into the lower leg of the inverter unit 13 (S20), the control unit 3 confirms that the UV phase is short-circuited, blocks the output of the inverter 1 (S25), sends fault information to the upper control system through the communication unit 5, and can display the fault information on the display unit 4 (S30). At this time, considering the circuit delay of the short-circuit detection unit 6, the output time of the effective vector can be set to be longer than the design time that can detect the short-circuit current. The design time that can detect the short-circuit current can be different according to the circuit configuration of the short-circuit detection unit 6, and is not limited to a certain value.

[0118] This diagnostic PWM control signal may be performed for the UV phase, the VW phase, and the WU phase ( S35 ).

[0119] That is, the control unit 3 can check whether the V phase and the W phase are short-circuited by applying a PWM control signal that causes the inverter unit 13 to output any one of the effective vectors [1 1 0], [0 1 0], [0 0 1], and [1 0 1]. Fig.30 This is a diagram showing how a short-circuit current flows through each effective vector when the VW phase is short-circuited.

[0120] like Fig.30As shown, the control unit 3 applies a PWM control signal that causes one of the above-mentioned effective vectors to be output. When the short-circuit detection unit 6 detects the current flowing into the lower leg of the inverter unit 13 (S20), the control unit 3 confirms that the UV phase is short-circuited, blocks the output of the inverter 1 (S25), and sends fault information to the upper control system through the communication unit 5. The fault information can be displayed on the display unit 4 (S30).

[0121] The control unit 3 can check whether the W phase and the U phase are short-circuited by applying a PWM control signal that outputs any one of the effective vectors [1 0 0], [1 1 0], [0 1 1], and [0 01]. Fig.31 This is a diagram showing how a short-circuit current flows through each effective vector when the WU phase is short-circuited.

[0122] like Fig.31 As shown, the control unit 3 applies a PWM control signal that causes one of the above-mentioned effective vectors to be output. When the short-circuit detection unit 6 detects the current flowing into the lower leg of the inverter unit 13 (S20), the control unit 3 confirms that the UV phase is short-circuited, blocks the output of the inverter 1 (S25), and sends fault information to the upper control system through the communication unit 5. The fault information can be displayed on the display unit 4 (S30).

[0123] On the other hand, in the absence of Figure 29 to Figure 31 When such a short-circuit current flows, the control unit 3 may apply a normal PWM control signal to the inverter unit 13 of the inverter 1 to start a normal operation ( S40 ).

[0124] As described above, according to one embodiment of the present invention, if the inverter 1 receives an operation command in the event of a short circuit, the control unit 3 can perform short circuit diagnosis in advance through the diagnostic PWM control signal and block the output of the inverter in advance, thereby protecting the inverter and the operator. Although the diagnostic PWM control signal is output when no short circuit occurs, due to the impedance of the motor 2, a large current will not flow in a shorter diagnostic PWM interval, so the possibility of misdiagnosis is very low.

[0125] Although the embodiments of the present invention are described above, they are merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent embodiments can be made to the embodiments. Therefore, the true technical protection scope of the present invention should be determined by the scope of the appended claims.

Claims

1. A control device, which is a control device for controlling an inverter, wherein: include: The inverter unit is composed of a plurality of switching elements, and converts the DC voltage into an AC voltage under the control of the control unit and outputs the AC voltage; a short-circuit detection unit that detects a short-circuit current flowing in the inverter unit; as well as The control unit applies a pulse width modulation (PWM) control signal to the inverter unit so that the inverter unit outputs at least one of a plurality of effective vectors for diagnosing a short circuit of an output of the inverter; The control unit sets the output time of the effective vector to be equal to or longer than a designed time for the short-circuit detection unit to detect the short-circuit current in consideration of a circuit delay of the short-circuit detection unit.

2. The control device according to claim 1, wherein: The inverter section is composed of three phase legs that output a three-phase AC voltage. The short-circuit detection unit detects a short-circuit current flowing into a lower leg of the three-phase legs.

3. The control device according to claim 1, wherein: The PWM control signal includes a signal that causes the inverter unit to output any one of [10 0], [0 1 0], [0 1 1], and [1 0 1] as the effective vector in response to a short circuit of the UV phases.

4. The control device according to claim 1, wherein: The PWM control signal includes a signal for causing the inverter unit to output one or more of [11 0], [0 1 0], [0 0 1], and [1 0 1] as the effective vector in response to a short circuit of the VW phase.

5. The control device according to claim 1, wherein: The PWM control signal includes a signal that causes the inverter unit to output one or more of [10 0], [1 1 0], [0 1 1], and [0 0 1] as the effective vector in response to a short circuit of the WU phase.

6. A control method, which is a method of controlling an inverter, wherein the inverter includes an inverter unit composed of a plurality of switching elements and converts a DC voltage into an AC voltage and outputs the AC voltage, wherein: The control method comprises: The step of receiving an operation instruction of the inverter; outputting a first PWM control signal to the inverter section so that the inverter section outputs at least one of a plurality of effective vectors for diagnosing a short circuit of an output of the inverter; and When a short-circuit current of the inverter unit is detected, blocking the output of the inverter; In consideration of a circuit delay of a short-circuit detection unit that detects a short-circuit current, the output time of the effective vector is set to be equal to or longer than a design time for the short-circuit detection unit to detect the short-circuit current.

7. The control method according to claim 6, wherein: The first PWM control signal includes a signal that causes the inverter unit to output any one of [1 0 0], [0 1 0], [0 1 1], and [1 0 1] as the effective vector in response to a short circuit of the UV phases.

8. The control method according to claim 6, wherein: The first PWM control signal includes a signal that causes the inverter unit to output one or more of [1 1 0], [0 1 0], [0 0 1], and [1 0 1] as the effective vector in response to a short circuit of the VW phase.

9. The control method according to claim 6, wherein: The first PWM control signal includes a signal that causes the inverter unit to output one or more of [1 0 0], [1 1 0], [0 1 1], and [0 0 1] as the effective vector in response to a short circuit of the WU phase.

10. The control method according to claim 6, wherein: The method further includes the step of outputting a second PWM control signal for normal operation of the inverter when the short-circuit current of the inverter unit is not detected.

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