CN106885965B - Device and method for fault detection of frequency converter - Google Patents
Device and method for fault detection of frequency converter Download PDFInfo
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- CN106885965B CN106885965B CN201510942999.6A CN201510942999A CN106885965B CN 106885965 B CN106885965 B CN 106885965B CN 201510942999 A CN201510942999 A CN 201510942999A CN 106885965 B CN106885965 B CN 106885965B
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- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/50—Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections
Abstract
The invention relates to a device and a method for fault detection of a frequency converter, wherein the device comprises the following components: the high-side shunt is connected in series with a direct-current positive bus between a rectifier and an inverter included in the frequency converter; the second acquisition module is used for acquiring the voltage drop of a low-side shunt, wherein the low-side shunt is connected in series on a direct-current negative bus between the rectifier and the inverter and has the same resistance value as the high-side shunt; and the comparison module is used for outputting an indication signal indicating that the frequency converter is short-circuited when the acquired voltage drop of the high-side current divider is not equal to the acquired voltage drop of the low-side current divider. The device and the method can improve the fault detection of the frequency converter.
Description
Technical Field
The present invention relates to frequency converters, and more particularly, to a method and apparatus for fault detection of a frequency converter.
Background
As shown in fig. 1, the inverter 10 generally includes a rectifier 12, a dc bus 14 formed by a dc positive bus P and a dc negative bus N, a filter capacitor 16, and an inverter 18.
The frequency converter 10 typically further comprises a fault detection module for detecting faults such as short-circuit, overcurrent and overload of the frequency converter 10. As shown in fig. 1, the fault detection module of the frequency converter 10 includes a high-side current divider 20, a low-side current divider 22, differential operational amplifiers 24 and 26, comparators 28 and 30, an optocoupler 32, and a controller MCU. The high side shunt 20 is connected in series to the positive dc bus P and the low side shunt 22 is connected in series to the negative dc bus N. The high side shunt 20 and the low side shunt 22 have the same resistance.
Since the short-circuit current is high when the frequency converter 10 is short-circuited, which may easily cause equipment damage and/or personal safety accidents, a high-resistance resistor R1 is usually connected between the neutral point N of the three-phase ac system SX and ground. Due to the resistor R1, the current flowing through the high-side shunt 20 and the low-side shunt 22 becomes smaller when the short circuit occurs in the inverter 10, resulting in a decrease in the accuracy of detecting the short circuit of the inverter 10.
Disclosure of Invention
In view of the above drawbacks of the prior art, embodiments of the present invention provide a method and apparatus for fault detection of a frequency converter, which can improve fault detection of the frequency converter.
The device for detecting the fault of the frequency converter comprises a first obtaining module, a second obtaining module and a comparing module. The first obtaining module is used for obtaining a voltage drop of a high-side shunt, wherein the high-side shunt is connected in series with a direct current positive bus between a rectifier and an inverter included in the frequency converter. The second obtaining module is used for obtaining the voltage drop of a low-side shunt, wherein the low-side shunt is connected in series on a direct current negative bus between the rectifier and the inverter and has the same resistance value as the high-side shunt. And the comparison module is used for outputting an indication signal indicating that the frequency converter is short-circuited when the acquired voltage drop of the high-side current divider is not equal to the acquired voltage drop of the low-side current divider.
The frequency converter according to the embodiment of the invention comprises a rectifier, an inverter, a filter capacitor, a high-side shunt resistor, a low-side shunt resistor and the device for fault detection. The rectifier is used for converting alternating current into direct current and outputting the direct current to a direct current bus formed by a direct current positive bus and a direct current negative bus. The inverter is used for converting the direct current on the direct current bus into three-phase alternating current and outputting the three-phase alternating current to the three phase lines. The filter capacitor is connected between the direct current positive bus and the direct current negative bus. The high-side shunt resistor is connected in series with the direct current positive bus. The low-side shunt resistor is connected in series with the direct-current negative bus and has the same resistance value as the high-side shunt. According to the embodiment of the invention, the method for detecting the fault of the frequency converter comprises the following steps: obtaining the voltage drop of a high-side shunt, wherein the high-side shunt is connected in series with a direct current positive bus between a rectifier and an inverter included in a frequency converter; obtaining the voltage drop of a low-side shunt, wherein the low-side shunt is connected in series on a direct-current negative bus between the rectifier and the inverter and has the same resistance value as the high-side shunt; and outputting an indication signal indicating that the frequency converter is short-circuited when the acquired voltage drop of the high-side shunt is not equal to the acquired voltage drop of the low-side shunt.
As can be seen from the above description, the embodiment of the present invention determines whether the frequency converter is short-circuited based on whether the voltage drops of the high-side shunt and the low-side shunt connected in series to the dc bus are equal, and since the currents flowing through the high-side shunt and the low-side shunt connected in series to the dc bus are not equal when the frequency converter is short-circuited, compared with the prior art, the embodiment of the present invention can accurately detect that the frequency converter is short-circuited even when the short-circuited current of the frequency converter is small, thereby improving the fault detection of the frequency converter.
Drawings
Other features, characteristics, benefits and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. Wherein:
fig. 1 shows a schematic diagram of a prior art frequency converter;
fig. 2A shows a schematic diagram of a frequency converter according to a first embodiment of the invention;
fig. 2B shows a schematic flow diagram of a method for fault detection of a frequency converter according to a first embodiment of the invention;
fig. 3A shows a schematic diagram of a frequency converter according to a second embodiment of the invention;
fig. 3B shows a schematic flow diagram of a method for fault detection of a frequency converter according to a second embodiment of the invention;
fig. 4A shows a schematic diagram of a frequency converter according to a third embodiment of the invention; and
fig. 4B shows a flow diagram of a method for fault detection of a frequency converter according to a third embodiment of the invention.
Detailed Description
Various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
Fig. 2A shows a schematic diagram of a frequency converter according to a first embodiment of the invention. As shown in fig. 2A, the frequency converter 100 may include a rectifier 102, a dc bus 104 composed of a dc positive bus P and a dc negative bus N, a filter capacitor 106, and an inverter 108. The dc bus 104 is connected between the rectifier 102 and the inverter 108, and the filter capacitor 106 is connected between the dc positive bus P and the dc negative bus N. The rectifier 102 converts alternating current AC1 having a frequency F1, supplied from a three-phase alternating current system 140 (a neutral point of which is grounded through a high-resistance resistor R1), into direct current and outputs the direct current to the direct current bus 104. The inverter 108 converts the dc power on the dc bus 104 into AC power AC2 having a frequency F2(F2 is different from F1) and outputs it on the three phase lines U, V and W at the output of the inverter 100. A load 150, such as a motor, may be connected to phase lines U, V and W to obtain alternating current AC2 having a frequency F2 as an operating power source.
The frequency converter 100 may also comprise a module BH1 for fault detection (hereinafter simply referred to as fault detection module BH 1). Fault detection module BH1 may include a high-side splitter 110, a low-side splitter 112, differential operational amplifiers 114, 116, and 118, a comparator 120, and a controller 122.
The high side shunt 110 and the low side shunt 112 have the same resistance. The high-side shunt 110 is connected in series to the positive dc bus P and is located between the rectifier 102 and the filter capacitor 106, and the low-side shunt 112 is connected in series to the negative dc bus N and is located between the rectifier 102 and the filter capacitor 106.
Two input terminals of the differential operational amplifier 114 are respectively connected to both ends of the high-side splitter 110 to obtain a potential across the high-side splitter 110, and the differential operational amplifier 114 calculates and outputs a potential difference across the high-side splitter 110 using the obtained potential across the high-side splitter 110. Because the high-side shunt 110 has a high voltage across it relative to ground, the differential operational amplifier 114 is preferably a differential operational amplifier that can withstand a high common-mode input voltage.
The differential operational amplifier 116 performs a predetermined shift on the potential difference output by the differential operational amplifier 114 to correct a calculation error of the differential operational amplifier 114 due to a high common mode input voltage. For example, but not limiting of, the differential operational amplifier 116 may achieve the predetermined translation by adding the potential difference output by the differential operational amplifier 114 to a predetermined reference voltage. The differential operational amplifier 116 outputs the translated potential difference as a voltage drop of the high-side splitter 110. The differential operational amplifier 116 is preferably a high precision differential operational amplifier.
The differential operational amplifier 114 and the differential operational amplifier 116 constitute an acquisition block for acquiring a voltage drop of the high-side shunt 110.
Two input terminals of the differential operational amplifier 118 are connected to both ends of the low-side shunt 112, respectively, to obtain potentials of both ends of the low-side shunt 112, and the differential operational amplifier 118 calculates and outputs a voltage drop of the low-side shunt 112 using the obtained potentials of both ends of the low-side shunt 112. It is apparent that the differential operational amplifier 118 is an acquisition module for acquiring the voltage drop of the low-side shunt 112. The differential operational amplifier 118 is preferably a high precision differential operational amplifier.
The comparator 120 as a comparison block outputs an indication signal indicating whether the frequency converter 100 is short-circuited to the controller 122 by comparing whether the voltage drop of the high-side shunt 110 output from the differential operational amplifier 116 and the voltage drop of the low-side shunt 112 output from the differential operational amplifier 118 are the same. Here, if the voltage drop of the high-side shunt 110 output by the differential operational amplifier 116 is different from the voltage drop of the low-side shunt 112 output by the differential operational amplifier 118, the comparator 120 outputs an indication signal indicating that the frequency converter 100 is short-circuited to the controller 122. If the voltage drop of the high-side shunt 110 output by the differential operational amplifier 116 is the same as the voltage drop of the low-side shunt 112 output by the differential operational amplifier 118, the comparator 120 outputs an indication signal to the controller 122 indicating that the frequency converter 100 is not shorted. The comparator 120 may be, but is not limited to, a window comparator.
When an indication signal is received from the comparator 120 indicating that the inverter 100 is shorted, the controller 122 performs a corresponding operation to avoid damage from the short circuit, such as, but not limited to, disconnecting the three-phase ac system 140 from the inverter 100.
Further, optionally, the controller 122 may also reconstruct the output current of the frequency converter 100 using the voltage drop of the low-side shunt 112 output by the differential operational amplifier 118 to check whether the frequency converter 100 is over-current and/or overloaded. Since it is prior art that the controller 122 reconstructs the output current of the frequency converter 100 using the voltage drop of the low-side shunt 112 to check whether the frequency converter 100 is over-current and/or overloaded, a detailed description thereof is omitted here.
As can be seen from the above description, the embodiment of the present invention determines whether the frequency converter 100 is short-circuited based on whether the voltage drops of the high-side shunt 110 and the low-side shunt 112 connected in series to the dc bus 104 are equal, and since the currents flowing through the high-side shunt 110 and the low-side shunt 112 connected in series to the dc bus 104 are unequal when the frequency converter 100 is short-circuited, the embodiment of the present invention can accurately detect that the frequency converter 100 is short-circuited even when the short-circuited current of the frequency converter 100 is small, thereby improving the fault detection of the frequency converter 100. In addition, the scheme of the embodiment of the invention can quickly protect and identify various short circuits of the frequency converter, and particularly provides reliable protection for a power supply system with a neutral point grounded in a high-resistance manner.
Fig. 2B shows a flow diagram of a method for fault detection of a frequency converter according to a first embodiment of the invention.
As shown in fig. 2B, the potential difference across high-side shunt 110 is calculated from the potential across high-side shunt 110, block 202. For example, but not limiting of, block 202 may be implemented by a differential operational amplifier 114.
At block 204, the outputted potential difference across the high-side splitter 110 is given a translation and the translated potential difference is outputted as a voltage drop of the high-side splitter 110. For example, but not limiting of, block 204 may be implemented by differential operational amplifier 116. Blocks 202 and 204 constitute operations for obtaining the voltage drop of the high-side shunt 110.
At block 206, the voltage drop of the low-side shunt 112 is obtained. For example, but not limiting of, block 206 may be implemented by differential operational amplifier 118.
At block 208, if the voltage drop of the acquired high-side shunt 100 is not equal to the voltage drop of the acquired low-side shunt 112, an indication signal indicating that the frequency converter 100 is shorted is output. For example, but not limiting of, block 208 may be implemented by comparator 120.
Further, optionally, the method shown in fig. 2B may further include a block 210, wherein based on the output indication signal indicating that the short circuit occurs in the frequency converter 100, a corresponding operation is performed to avoid damage caused by the short circuit. For example, but not limiting of, block 210 may be implemented by controller 122.
Fig. 3A shows a schematic diagram of a frequency converter according to a second embodiment of the invention. As shown in fig. 3A, the frequency converter 300 may include a rectifier 102, a dc bus 104 composed of a dc positive bus P and a dc negative bus N, a filter capacitor 106, and an inverter 108. The dc bus 104 is connected between the rectifier 102 and the inverter 108, and the filter capacitor 106 is connected between the dc positive bus P and the dc negative bus N. The rectifier 102 converts alternating current AC1 having a frequency F1, supplied from a three-phase alternating current system 140 (a neutral point of which is grounded through a high-resistance resistor R1), into direct current and outputs the direct current to the direct current bus 104. The inverter 108 converts the dc power on the dc bus 104 into AC power AC2 having a frequency F2(F2 is different from F1) and outputs it on the three phase lines U, V and W at the output of the inverter 300. Load 150 may be connected to phase lines U, V and W to obtain alternating current AC2 having a frequency F2 as the operating power source.
The frequency converter 300 may further include a fault detection module BH2 for identifying a faulty phase line, such as a short circuit or an open circuit, among the three phase lines U, V and W. The failure detection module BH2 may include an indication module 310 and a controller 350.
The indication module 310 may include resistors 312, 314, and 316, and optical couplers 318 and 320.
The photosensitive devices of optocoupler 318 and the photosensitive devices of optocoupler 320 are connected to controller 350 to output signal S to controller 350UVSum signal SWV. Wherein the signal SUVIndicating the voltage between the phases U and VSignal SWVIndicating the voltage between phase W and phase V. Signal SUVSum signal SWVCan be viewed as a signal that instructs the module 310 to generate and output.
Signal SUVAnd SWVIs a Pulse Width Modulated (PWM) signal. The inventor finds that: when neither of phase lines U, V or W has a fault such as a short circuit or an open circuit, signal S is transmittedUVAnd SWVThe phase difference between them is 240 degrees, the signal SUVAnd SWVIs the same and may be determined based on the frequency F2 of the alternating current AC2 on the phase lines U, V and W; when one of the phases U, V and W is short-circuited or broken, the signal SUVAnd SWVIs not equal to 240 degrees, and the signal SUVAnd SWVThe duty cycle of the signal associated with the failed phase line is not equal to the predetermined duty cycle and the duty cycle of the signal not associated with the failed phase line is equal to the predetermined duty cycle, wherein the predetermined duty cycle is equal to the signal S when neither phase line U, V nor W has failed, such as a short circuit or an open circuitUVAnd SWVThe duty cycle of (c).
With the above findings, the controller 350 outputs the signal S based on the indication module 310UVAnd SWVThe phase difference to identify the failed one of the phase lines U, V and W. In particular, upon receiving the signal S from the indication module 310UVAnd SWVThereafter, the controller 350 calculates the received signal SUVAnd SWVThe respective duty cycles and the phase difference between them. Then, the controller 350 determines whether the calculated phase difference is equal to 240 degrees and the calculated signal SUVAnd SWVWhether or not the respective duty ratios are equal to a predetermined duty ratio ZK (the predetermined duty ratio ZK is equal to the signal S when neither of the phase lines U, V and W has a fault such as a short circuit or an open circuit)UVAnd SWVDuty cycle of). If the judgment result shows that the calculated phase difference is not equal to 240 degrees, and the signal SUVAnd SWVThe duty cycle of the signal associated with a particular one of the phase lines U, V and W is not equal to the predetermined duty cycle ZK and the duty cycle of the signal not associated with the particular phase lineThe ratio is equal to the predetermined duty cycle ZK, the controller 350 determines that the particular phase line is the failed phase line.
In particular, if the result of the determination indicates that the calculated phase difference is not equal to 240 degrees, the signal S associated with the phase line UUVIs not equal to the predetermined duty cycle ZK and is not associated with the phase line UWVIf the duty ratio is equal to the predetermined duty ratio ZK, the controller 350 determines that the phase line U is a failed phase line; if the result of the determination indicates that the calculated phase difference is not equal to 240 degrees, the signal S associated with the phase line WWVIs not equal to the predetermined duty cycle ZK and is not associated with the phase line WUVIs equal to the predetermined duty cycle ZK, the controller 350 determines that the phase line W is a failed phase line; and, if the result of the determination indicates that the calculated phase difference is not equal to 240 degrees, the signal S associated with the phase line VUVAnd SWVIs not equal to the predetermined duty cycle ZK, the controller 350 determines that the phase line V is the failed phase line.
When optocouplers 318 and 320 are turned on, a small virtual neutral point N' is formed within indicator block 310, where indicator block 310 forms a star-shaped high impedance network, and thus the presence of fault detection block BH2 has no effect on load 150.
It will be understood by those skilled in the art that although in the above description, the two signals generated by the indication module 310 are the signal S indicating the current between the phases U and VUVAnd a signal S indicating the current between the phases W and VWVHowever, the present invention is not limited thereto. For example, the two signals generated by the indication module 310 may also be a signal S indicating the current between the phases W and VWVAnd a signal S indicating the current between the phases W and UWUAlternatively, the two signals generated by the indication module 310 may also be the signal S indicating the current between the phases W and UWUAnd a signal S indicating the current between the phases U and VUV。
Fig. 3B shows a flow diagram of a method for fault detection of a frequency converter according to a second embodiment of the invention.
As shown in fig. 3B, at block 302, two signals are generated, each indicative of a current flow between two of the phase lines U, V and W at the output of the frequency converter 300. For example, but not limiting of, block 302 may be implemented by indication module 310.
At block 304, the phase lines U, V and W that are shorted or open are identified based on the waveform change and phase difference of the two signals generated. Specifically, if the phase difference between the two signals is not equal to 240 degrees, and the duty ratio of the signal associated with a specific phase line among the phase lines U, V and W is not equal to the predetermined duty ratio and the duty ratio of the signal not associated with the specific phase line is equal to the predetermined duty ratio, it is determined that the specific phase line is a phase line in which short circuit or open circuit occurs, wherein the predetermined duty ratio is equal to the duty ratio of the two signals when no short circuit or open circuit occurs in the three phase lines U, V and W. For example, but not limiting of, block 304 may be implemented by controller 350.
Fig. 4A shows a schematic diagram of a frequency converter according to a third embodiment of the invention. As shown in fig. 4A, the frequency converter 400 may include a rectifier 102, a dc bus 104 composed of a dc positive bus P and a dc negative bus N, a filter capacitor 106, and an inverter 108. The dc bus 104 is connected between the rectifier 102 and the inverter 108, and the filter capacitor 106 is connected between the dc positive bus P and the dc negative bus N. The rectifier 102 converts alternating current AC1 having a frequency F1 provided by a three-phase alternating current system 140 (the neutral point of which is grounded through a high-resistance resistor) into direct current and outputs the direct current to the direct current bus 104. The inverter 108 converts the dc power on the dc bus 104 into AC power AC2 having a frequency F2(F2 is different from F1) and outputs it on the three phase lines U, V and W at the output of the inverter 300. Load 150 may be connected to phase lines U, V and W to obtain alternating current AC2 having a frequency F2 as the operating power source.
The frequency converter 400 may also comprise a fault detection module BH 3. The fault detection module BH3 is composed of a combination of the fault detection module BH1 in the first embodiment and the fault detection module BH2 in the second embodiment, and the controller 450 included in the fault detection module BH3 has functions of both the controller 122 and the controller 350. Since the above-described failure detection module BH1 in the first embodiment and the failure detection module BH2 in the second embodiment have been described in detail, the structure and function of the failure detection module BH3 will be clear to those skilled in the art, and a detailed description thereof will be omitted here.
Fig. 4B shows a flow diagram of a method for fault detection of a frequency converter according to a third embodiment of the invention. The method shown in FIG. 4B includes blocks 202 and 208 in the first embodiment and blocks 302 and 304 in the second embodiment. Since the above-mentioned blocks 202 and 208 and 302 and 304 in the first and second embodiments have been described in detail, the method shown in FIG. 4B is clear to those skilled in the art, and the detailed description thereof is omitted here. Furthermore, those skilled in the art will appreciate that the blocks 302 and 304 shown in FIG. 4B may also be performed before the blocks 202 and 208 shown in FIG. 4B or both.
Other variants
It should be understood by those skilled in the art that although in the above first and third embodiments, the high-side shunt 110 and the low-side shunt 112 are located between the rectifier 102 and the filter capacitor 106, the present invention is not limited thereto. In other embodiments of the present invention, high-side shunt 110 and low-side shunt 112 may also be located between filter capacitor 106 and inverter 108.
It should be understood by those skilled in the art that although in the above first and third embodiments, the obtaining module for obtaining the voltage drop of the high-side shunt 110 includes two differential operational amplifiers, i.e., the differential operational amplifiers 114 and 116, the present invention is not limited thereto. In other embodiments of the present invention, the obtaining module for obtaining the voltage drop of the high-side current divider 110 may be implemented by a differential operational amplifier, such as, but not limited to, a differential operational amplifier capable of withstanding a high common-mode input voltage and having high precision. Alternatively, the obtaining module for obtaining the voltage drop of the high-side shunt 110 and the obtaining module for obtaining the voltage drop of the low-side shunt 112 may be implemented by other suitable devices besides the differential operational amplifier.
It should be understood by those skilled in the art that although in the above second and fourth embodiments, the controller 350 identifies the failed phase line among the phase lines U, V and W based on both the waveform change and the phase difference of the signal output from the indicating module 310, the present invention is not limited thereto. In other embodiments of the present invention, the controller 350 may identify the failed phase line U, V and W based only on the waveform change of the signal output by the indicating module 310.
It should be understood by those skilled in the art that although in the above second and fourth embodiments, the indication module 310 includes only two optical couplers 318 and 320 to generate the two signals SUVAnd SWVHowever, the present invention is not limited thereto. In other embodiments of the present invention, the indication module 310 may include a third optical coupler in addition to the optical couplers 318 and 320. The light emitting device of the third optocoupler having two ends connected to the other end of the resistor 312 and the other end of the resistor 316, respectively, outputs a signal S indicative of the current between the phase lines U and WUWAs a third signal generated and output by the indication module 310.
Three signals S are generated and output at the indication module 310UV、SWVAnd SUWIn this case, the controller 350 may be based on only the three signals SUV、SWVAnd SUWTo identify the failed phase line among phase lines U, V and W. In particular, if three signals S from the indication module 310UV、SWVAnd SUWThe duty cycle of the signal associated with a particular phase line among phase lines U, V and W is not equal to the predetermined duty cycle and the duty cycle of the signal not associated with the particular phase line is equal to the predetermined duty cycle, controller 350 determines that the particular phase line is a short-circuited or open-circuited phase line, where the predetermined duty cycle is equal to signal S when neither phase line U, V nor W is short-circuited or open-circuitedUV、SWVAnd SUWThe duty cycle of (c).
For example, if the signal S is associated with the phase line UUVAnd SUWIs not equal to the predetermined duty cycle and is not associated with phase line UWVIs equal to the predetermined duty cycle, the controller 350 determines that the phase line U is a short-circuited or open-circuited phase line. If the signal S associated with the phase line VUVAnd SWVIs not equal to the predetermined duty cycle and is not associated with the phase line VUWIs equal to the predetermined duty cycle, the controller 350 determines that the phase line V is a short-circuited or open-circuited phase line. If the signal S associated with the phase line WUWAnd SWVIs not equal to the predetermined duty cycle and is not associated with the phase line WUVIs equal to the predetermined duty cycle, the controller 350 determines that the phase line W is a short-circuited or open-circuited phase line.
It should be understood by those skilled in the art that the solutions of the embodiments of the present invention are not only applicable to the case where the neutral point of the three-phase ac system 140 is grounded through a resistor with a high resistance value, but also applicable to the case where the neutral point of the three-phase ac system 140 is grounded through a resistor with a low resistance value or is not grounded through a resistor.
It will be appreciated by those skilled in the art that in the above second and fourth embodiments, the fault detection module may further include a comparator BJ for comparing the voltage drop of the high-side shunt 110 output by the differential operational amplifier 116 with a voltage threshold for indicating a short circuit and outputting an indication signal indicating that the inverter is short-circuited to the controller when the voltage drop of the high-side shunt 110 is greater than the voltage threshold for indicating a short circuit, so that the inverter of the embodiment of the present invention can be quickly detected when the inverter is connected to the three-phase ac system 140 in which the neutral point is grounded through a resistor of low resistance or not grounded through the resistor.
Those skilled in the art will appreciate that various modifications, adaptations, and variations may be made to the various embodiments disclosed above without departing from the spirit of the invention, and that such modifications, adaptations, and variations are intended to be within the scope of the invention. The scope of the invention is therefore defined by the appended claims.
Claims (10)
1. An apparatus for fault detection of a frequency converter, comprising:
the voltage control method comprises a first obtaining module, a second obtaining module and a third obtaining module, wherein the first obtaining module is used for obtaining the voltage drop of a high-side current divider (110), and the high-side current divider (110) is connected in series on a direct current positive bus P between a rectifier (102) and an inverter (108) which are included in a frequency converter;
a second obtaining module (118) for obtaining a voltage drop of a low-side shunt (112), wherein the low-side shunt (112) is connected in series to a negative dc bus N between the rectifier (102) and the inverter (108) and has the same resistance as the high-side shunt (110);
a comparison module (120) for outputting an indication signal indicating that the frequency converter is short-circuited when the obtained voltage drop of the high-side shunt (110) and the obtained voltage drop of the low-side shunt (112) are not equal;
an indicating module (310) for generating a plurality of signals, each signal indicating a voltage between two of the three phase lines U, V, W of the output of the frequency converter; and
a controller for identifying a phase line among the three phase lines U, V, W that is short-circuited or open-circuited based on at least waveform variations of the plurality of generated signals;
wherein the controller determines that a particular phase line of the plurality of signals U, V, W is a shorted or open phase line if the duty cycle of the signal associated with the particular phase line is not equal to a predetermined duty cycle and the duty cycle of the signal not associated with the particular phase line is equal to the predetermined duty cycle, wherein the predetermined duty cycle is equal to the duty cycle of the plurality of signals when none of the three phase lines U, V, W are shorted or open.
2. The apparatus of claim 1, wherein the first obtaining means comprises:
a first differential operational amplifier (114) having two input terminals respectively connected to two ends of the high side current divider (110) for calculating and outputting a potential difference between the two ends of the high side current divider (110) according to a potential between the two ends of the high side current divider (110); and
a second differential operational amplifier (116) for performing a specified translation of the outputted potential difference and outputting the translated potential difference as a voltage drop of the high-side shunt (110).
3. The apparatus of claim 1 or 2, further comprising:
and the controller is used for executing corresponding operation to avoid damage caused by short circuit based on the indication signal.
4. The apparatus of claim 1, wherein,
the plurality of signals are two signals, an
The controller determines that the particular phase line is a short-circuited or open-circuited phase line if the phase difference between the two signals is not equal to 240 degrees, and the duty cycle of the signal associated with the particular phase line of the two signals is not equal to the predetermined duty cycle and the duty cycle of the signal not associated with the particular phase line is equal to the predetermined duty cycle.
5. The apparatus of claim 4, wherein,
the indication module comprises a first resistor (312), a second resistor (314), a third resistor (316), a first optocoupler (318), and a second optocoupler (320),
wherein one end of the first resistor (312), one end of the second resistor (314) and one end of the third resistor (316) are respectively connected with one of the three phase lines, the other end of the first resistor (312) and the other end of the second resistor (314) are respectively connected with two ends of the light emitting device of the first optical coupler (318), and the other end of the second resistor (314) and the other end of the third resistor (316) are respectively connected with two ends of the light emitting device of the second optical coupler (320),
wherein the two signals are signals output by photosensitive devices of the first (318) and second (320) optocouplers.
6. A frequency converter, comprising:
the rectifier (102) is used for converting alternating current into direct current and outputting the direct current to a direct current bus (104) formed by a direct current positive bus P and a direct current negative bus N;
an inverter (108) for converting the direct current on the direct current bus (104) into three-phase alternating current and outputting the three-phase alternating current to the three phase lines U, V, W;
a filter capacitor (106) connected between the positive DC bus P and the negative DC bus N;
a high side shunt (110) connected in series to the direct current positive bus P;
the low-side current divider (112) is connected in series with the direct-current negative bus N and has the same resistance value as the high-side current divider (110); and
the device of any one of claims 1-5.
7. A method for fault detection of a frequency converter, comprising:
obtaining the voltage drop of a high-side current divider (110), wherein the high-side current divider (110) is connected in series on a direct current positive bus P between a rectifier (102) and an inverter (108) which are included in the frequency converter;
obtaining the voltage drop of a low-side current divider (112), wherein the low-side current divider (112) is connected in series on a direct current negative bus N between the rectifier (102) and the inverter (108) and has the same resistance value as the high-side current divider (110);
outputting an indication signal indicating that the frequency converter is short-circuited when the obtained voltage drop of the high-side shunt (110) is not equal to the obtained voltage drop of the low-side shunt (112);
generating a plurality of signals, each signal indicative of a voltage between two of the three phase lines U, V, W of the output of the frequency converter; and
identifying one of the three phase lines U, V, W that is shorted or open based on at least waveform variations of the generated plurality of signals; wherein the identifying comprises:
determining that a particular phase line of the plurality of signals is a phase line in which a short circuit or an open circuit occurs if a duty cycle of a signal associated with the particular phase line is not equal to a predetermined duty cycle and a duty cycle of a signal not associated with the particular phase line is equal to the predetermined duty cycle, wherein the predetermined duty cycle is equal to the duty cycle of the plurality of signals when none of the three phase lines are short or open.
8. The method of claim 7, wherein obtaining the voltage drop of the high-side shunt (110) comprises:
calculating and outputting a potential difference across the high side shunt (110) from a potential across the high side shunt (110);
performing a specified translation of the outputted potential difference; and
outputting the translated potential difference as a voltage drop of the high side shunt (110).
9. The method of claim 7 or 8, further comprising:
based on the indication signal, corresponding operation is carried out to avoid damage caused by short circuit.
10. The method of claim 7, wherein,
the plurality of signals are two signals, an
The identifying comprises: and if the phase difference between the two signals is not equal to 240 degrees, and the duty ratio of the signal associated with the specific phase line in the two signals is not equal to the preset duty ratio and the duty ratio of the signal not associated with the specific phase line is equal to the preset duty ratio, determining that the specific phase line is the phase line with short circuit or open circuit.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101876681A (en) * | 2009-04-28 | 2010-11-03 | 沈阳高精数控技术有限公司 | Method for detecting ground short circuit of output side of AC servo driver or low voltage inverter |
| JP2011085506A (en) * | 2009-10-16 | 2011-04-28 | Fuji Electric Systems Co Ltd | Testing apparatus for power converter |
| CN102944770A (en) * | 2012-10-22 | 2013-02-27 | 奇瑞汽车股份有限公司 | Intelligent testing system of IGBT (Insulated Gate Bipolar Translator) and drive combined module and testing method thereof |
| CN203551649U (en) * | 2013-08-22 | 2014-04-16 | 深圳市伟创电气有限公司 | Real-time detection circuit for over-current protection of frequency converter |
| CN103986310A (en) * | 2014-05-30 | 2014-08-13 | 台达电子企业管理（上海）有限公司 | Current converter circuit and open circuit detection method thereof |
-
2015
- 2015-12-16 CN CN201510942999.6A patent/CN106885965B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101876681A (en) * | 2009-04-28 | 2010-11-03 | 沈阳高精数控技术有限公司 | Method for detecting ground short circuit of output side of AC servo driver or low voltage inverter |
| JP2011085506A (en) * | 2009-10-16 | 2011-04-28 | Fuji Electric Systems Co Ltd | Testing apparatus for power converter |
| CN102944770A (en) * | 2012-10-22 | 2013-02-27 | 奇瑞汽车股份有限公司 | Intelligent testing system of IGBT (Insulated Gate Bipolar Translator) and drive combined module and testing method thereof |
| CN203551649U (en) * | 2013-08-22 | 2014-04-16 | 深圳市伟创电气有限公司 | Real-time detection circuit for over-current protection of frequency converter |
| CN103986310A (en) * | 2014-05-30 | 2014-08-13 | 台达电子企业管理（上海）有限公司 | Current converter circuit and open circuit detection method thereof |
Non-Patent Citations (1)
| Title |
|---|
| 高压变频器驱动故障的检测分析;赵曙伟 等;《华电技术》;20130630;第35卷(第6期);第21-24页 * |
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