CN110148925A - For the guard method of motor ground fault and frequency converter in frequency converter - Google Patents
For the guard method of motor ground fault and frequency converter in frequency converter Download PDFInfo
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- CN110148925A CN110148925A CN201910308639.9A CN201910308639A CN110148925A CN 110148925 A CN110148925 A CN 110148925A CN 201910308639 A CN201910308639 A CN 201910308639A CN 110148925 A CN110148925 A CN 110148925A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
- H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
- H02H7/085—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors against excessive load
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
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- Control Of Ac Motors In General (AREA)
Abstract
The present invention relates to power electronics fields; more particularly to a kind of guard method for motor ground fault in frequency converter; it powers in frequency converter and after relay actuation; bridge Q2 under the IGBT of the IGBT unit of each phase IGBT unit is set to sequentially turn on time t; or bridge Q1 on Q2 bridge or IGBT is made under the IGBT of each phase IGBT unit to simultaneously turn on time t; 0 < t <, 10 μ s; output electric current according to each phase IGBT unit; judge whether motor occurs ground fault in frequency converter; it is easy to operate, accuracy of judgement and IGBT circuit is not damaged；Invention additionally discloses a kind of frequency converters using above-mentioned guard method, and circuit structure is simple, efficiently can accurately judge whether motor occurs short trouble, and do not damage to the IGBT circuit of frequency converter.
Description
Technical field
The present invention relates to power electronics fields, and in particular to a kind of protection for motor ground fault in frequency converter
Method further relates to a kind of frequency converter using above-mentioned guard method.
Background technique
Frequency converter is the AC power source that power frequency supply (50Hz/60Hz) is transformed into various frequencies, to realize the change of motor
The key equipment of speed operation.Frequency converter can reduce electric power line voltage fluctuation, reduce the impact to power grid, avoid peak valley difference value
Problems of too, the starting current of also controllable motor, reduces the maintenance cost of motor；
With more mature, core competitiveness of the reliable defencive function as frequency converter of converter technology.City at present
The motor earth-fault protection of upconverter be after frequency converter operation (in the operational process of frequency converter) by three-phase current
Detection judges whether what overcurrent was protected.This there is a problem: even if detection electric current is realized after frequency converter operation
Motor earth-fault protection, damage to IGBT or bigger often will cause IGBT failure, or even there is protection
The case where directly damaging IGBT (insulated gate bipolar transistor) not in time.And existing Small-power Inverter is not provided with and connects
Earth fault protection.
Summary of the invention
It is an object of the invention to overcome the deficiencies of existing technologies, provide a kind of for motor ground fault in frequency converter
Guard method, it is easy to operate, can accurate judgement motor short trouble whether occurs, and the IGBT circuit of frequency converter is not caused
Damage；A kind of frequency converter is also provided, circuit structure is simple, it efficiently can accurately judge whether motor occurs short trouble,
And the IGBT circuit of frequency converter is not damaged.
To achieve the above object, present invention employs following technical solutions:
A kind of guard method for motor ground fault in frequency converter, frequency converter include IGBT circuit, charging resistor with
And the relay in parallel with charging resistor, IGBT circuit include U phase IGBT unit, V phase IGBT unit and W phase IGBT unit, often
Phase IGBT unit includes that bridge Q2, U phase IGBT unit, V phase IGBT unit and W phase IGBT unit divide under bridge Q1 and IGBT on IGBT
It is not connected with the coil windings of the coil windings of the U phase of motor, the coil windings of V phase and W phase；
The frequency converter powers on and after relay actuation:
Successively make on the IGBT of U phase IGBT unit bridge Q1 and W phase IGBT unit on the IGBT of bridge Q1, V phase IGBT unit
IGBT 10 μ s of upper bridge Q1 turn-on time t, 0 < t < obtains U phase IGBT unit, V phase IGBT unit and W phase IGBT unit respectively
Electric current, and the output electric current according to each phase are exported, judges the coil windings of the U phase of motor, the coil windings of V phase and W phase respectively
Coil windings ground short circuit failure whether occurs；
Alternatively, making on the IGBT of U phase IGBT unit that bridge Q1 and W phase IGBT is mono- on the IGBT of bridge Q1, V phase IGBT unit simultaneously
Bridge Q1 turn-on time 10 μ s of t, 0 < t < on the IGBT of member obtains U phase IGBT unit, V phase IGBT unit in time t respectively
Judge whether motor occurs ground short circuit failure according to the output electric current of each phase with the output electric current of W phase IGBT unit；
Alternatively, making under the IGBT of U phase IGBT unit that bridge Q2 and W phase IGBT is mono- under the IGBT of bridge Q2, V phase IGBT unit simultaneously
Bridge Q2 turn-on time 10 μ s of t, 0 < t < under the IGBT of member obtains U phase IGBT unit, V phase IGBT unit in time t respectively
Judge whether motor occurs ground short circuit failure according to the output electric current of each phase with the output electric current of W phase IGBT unit.
A kind of frequency converter, guard method of the application for motor ground fault in frequency converter；Bridge on each IGBT
The grid G of Q1 is connected with the output end of an optocoupler PC1, and the grid G of bridge Q2 is defeated with optocoupler PC2 under each IGBT
Outlet is connected, and the input terminal of optocoupler PC1 and optocoupler PC2 are connected with the output end of single-chip microcontroller, and U phase IGBT unit, V phase IGBT are mono-
Node on first, W phase IGBT unit IGBT under bridge Q1 and IGBT between bridge Q2 respectively passes through a current sensor HL1 and motor
The coil windings of U phase, the coil windings of V phase, the coil windings of W phase be connected, current sensor HL1 is connected with single-chip microcontroller.
Preferably, the single-chip microcontroller includes output end DV+ and output end DV-, the anode of the light emitting diode of optocoupler PC1,
Cathode is connected with output end DV+ and output end DV- respectively, the anode of the light emitting diode of optocoupler PC2, cathode respectively with output end
DV- is connected with output end DV+.
Preferably, after the frequency converter powers on, single-chip microcontroller exports low level by output end DV+, output end DV- respectively,
After relay actuation:
The single-chip microcontroller exports high level by output end DV+ and exports low level by output end DV-, then optocoupler PC1
Bridge Q1 on IGBT is connected in conducting；
The single-chip microcontroller exports low level by output end DV+ and exports high level by output end DV-, then optocoupler PC2
Bridge Q2 under IGBT is connected in conducting.
Preferably, the output end phase that the grid G of bridge Q1 passes through a resistance R1 and an optocoupler PC1 on each IGBT
Even, the grid G of bridge Q1 is connected by a resistance R2 with the emitter E of bridge on the IGBT on each IGBT, bridge under each IGBT
The grid G of Q2 is connected by a resistance R3 with the output end of an optocoupler PC2, and the grid G of bridge Q2 passes through one under each IGBT
A resistance R4 is connected with the emitter E of bridge under the IGBT；Bridge under the emitter E of bridge Q1 and IGBT on the IGBT of same IGBT unit
The collector C of Q2 is connected.
Preferably, the current sensor HL1 passes through capacitor C1, capacitor C2 ground connection respectively.
Preferably, the single-chip microcontroller includes output end DV+, the end output end DV- and I/O；The light-emitting diodes of each optocoupler PC1
Anode, the cathode of pipe are connected with output end DV+, output end DV- respectively, the 8th foot of each optocoupler PC1 with VP+15V power supply phase
Even, the 5th foot of each optocoupler PC1 is connected with VP-10V power supply, and the 6th foot and the 7th foot of each optocoupler PC1 is connected and passes through one
A resistance R1 is connected with the grid G of bridge Q1 on an IGBT；The anode of the light emitting diode of each optocoupler PC2, cathode respectively with
Output end DV-, output end DV+ are connected, and the 8th foot of each optocoupler PC2 is connected with VP+15V power supply, and the 5th of each optocoupler PC2 the
Foot is connected with VP-10V power supply, and the 6th foot and the 7th foot of each optocoupler PC2 is connected and passes through an a resistance R3 and IGBT
The grid G of lower bridge Q2 is connected；The emitter E of bridge Q1 passes through the grid of bridge Q1 on the resistance R2 and IGBT on each IGBT
G be connected, each IGBT on the emitter E of bridge Q1 be grounded VPGND be connected, on each IGBT the collector C of bridge Q1 with change
The anode of frequency device main circuit is connected；The emitter E of bridge Q2 passes through bridge Q2 under the resistance R4 and IGBT under each IGBT
Grid G is connected, and the emitter E of bridge Q2 is connected with ground connection VDGND under each IGBT, and the emitter E of bridge Q2 is equal under each IGBT
It is connected with the cathode of main circuit of converter；On the IGBT of same IGBT unit under the emitter E of bridge Q1 and IGBT bridge Q21 current collection
Pole C is connected, and on the IGBT of same IGBT unit under bridge Q1 and IGBT the node of bridge Q2 and a current sensor HL1 the 6th
Foot is connected, and the 5th foot of each current sensor HL1 is connected to the motor, and the 1st foot of each current sensor HL1 passes through capacitor C1
It being grounded and is connected with -15V power supply, the 3rd foot of each current sensor HL1 is grounded by capacitor C2 and is connected with+15V power supply,
The 4th foot of each current sensor HL1 is connected with the end I/O of single-chip microcontroller, the 2nd foot ground connection of each current sensor HL1.
It preferably, further include the ground fault alarm structure being connected with single-chip microcontroller, single-chip microcontroller detects that the ground connection of motor is short
When the failure of road, ground fault alarm structure issues alarm signal；The protection system further includes earth-fault protection, monolithic
When machine examination measures the ground short circuit failure of motor, earth-fault protection is triggered, cuts off circuit.
Guard method for motor ground fault in frequency converter of the invention powers in frequency converter and relay is attracted
Afterwards, so that bridge Q1 on the IGBT of each phase IGBT unit is sequentially turned on time t, or make bridge Q1 on the IGBT of each phase IGBT unit while leading
Logical time t, or bridge Q2 under the IGBT of each phase IGBT unit is made to simultaneously turn on time t, and 0 < t <, 10 μ s, it is mono- to obtain each phase IGBT
The output electric current of member, the output electric current according to each phase IGBT unit judge motor with the presence or absence of ground fault, due to each phase IGBT
Unit turn-on time t is strictly controlled within 10 μ s, even if there are short troubles for motor, since each phase IGBT unit is switched on
Time t it is very short, therefore each phase IGBT unit can't be damaged, and single-chip microcontroller is directly with the defeated of each phase IGBT unit
Electric current is judgment basis out, ensure that the accuracy of judging result；Further, bridge on the IGBT for making each phase IGBT unit
Q1 sequentially turns on time t, and obtains the output electric current of each phase IGBT unit, and the output electric current according to each phase IGBT unit judges electricity
The coil windings of each phase of machine whether there is short trouble, is conducive to the position for more accurately judging electrical fault, is
Repair and maintenance personnel provide convenience, improve repair and maintenance efficiency；Guard method of the invention, easy to operate, judging result essence
Standard, and IGBT circuit will not be damaged, it can effectively extend the service life of frequency converter.
Frequency converter of the invention, using the guard method for motor ground fault in frequency converter of the invention, circuit
Structure is simple, and deterministic process is efficient, and will not the IGBT circuit to frequency converter damage, can effectively extend the use of frequency converter
Service life.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of frequency converter of the present invention.
Specific embodiment
Below in conjunction with the embodiment that attached drawing 1 provides, the specific embodiment of frequency converter of the invention is further illustrated.This hair
Bright frequency converter is not limited to the following description.
Frequency converter of the invention uses the guard method for motor ground fault in frequency converter of the invention, frequency conversion
Device includes IGBT circuit, charging resistor and the relay in parallel with charging resistor, and IGBT circuit includes U phase IGBT unit, V phase
IGBT unit and W phase IGBT unit, each IGBT unit include bridge Q2 under bridge Q1 and IGBT on IGBT；It is characterized by: every
The grid G of bridge is connected with the output end of an optocoupler PC1 on a IGBT, and the grid G of bridge Q2 is with one under each IGBT
The output end of a optocoupler PC2 is connected, and the input terminal of optocoupler PC1 and optocoupler PC2 are connected with the output end of single-chip microcontroller, U phase IGBT
Unit, V phase IGBT unit, W phase IGBT unit IGBT on node under bridge Q1 and IGBT between bridge Q2 respectively pass through an electricity
Flow sensor HL1 is connected with the coil windings of the coil windings of U phase of motor, the coil windings of V phase, W phase, current sensor
HL1 is connected with single-chip microcontroller；
The frequency converter powers on and after relay actuation:
The optocoupler PC1 that the single-chip microcontroller controls each phase is sequentially turned on and is controlled the optocoupler PC2 of each phase and is held off, and makes each phase
Bridge Q1 sequentially turns on bridge Q2 under the IGBT of time t and each phase IGBT unit and is held off on the IGBT of IGBT unit, 0 < t <, 10 μ
S, the current sensor HL1 of each phase detects the output electric current of each phase IGBT respectively, and the current signal that will test is transferred to monolithic
Machine, single-chip microcontroller judge whether the coil windings of each phase of motor occur ground short circuit according to current signal；
It is held off alternatively, the optocoupler PC1 that the single-chip microcontroller controls each phase is simultaneously turned on and controlled the optocoupler PC2 of each phase,
Bridge Q1 on the IGBT of each phase IGBT unit is set to simultaneously turn on time t, 0 < t <, 10 μ s, in time t, the current sensor of each phase
The current signal for each phase that HL1 detects the output electric current of each phase IGBT unit respectively, and will test respectively is transferred to single-chip microcontroller,
Single-chip microcontroller judges whether motor occurs ground short circuit failure according to the current signal of each phase；
It is held off alternatively, the optocoupler PC2 that the single-chip microcontroller controls each phase is simultaneously turned on and controlled the optocoupler PC1 of each phase,
Bridge Q2 under the IGBT of each phase IGBT unit is set to simultaneously turn on time t, 0 < t <, 10 μ s, in time t, the current sensor of each phase
HL1 detects the output electric current of each phase IGBT unit respectively, and the current signal that will test respectively is transferred to single-chip microcontroller, single-chip microcontroller
Current signal according to each phase judges whether motor occurs ground short circuit failure.
Frequency converter of the invention, using the guard method for motor ground fault in frequency converter of the invention, circuit
Structure is simple, and deterministic process is efficient, after frequency converter powers on and relay is attracted, controls each phase IGBT unit by single-chip microcontroller
The upper bridge Q1 of IGBT sequentially turns on bridge Q1 on time t, or the IGBT of each phase IGBT unit of control and simultaneously turns on time t, or control is respectively
Bridge Q2 simultaneously turns on time t, and 0 < t <, 10 μ s under the IGBT of phase IGBT unit, and by with each concatenated electricity of phase IGBT unit
Flow sensor HL1 measures the output electric current of each phase IGBT unit, and the output electric current by single-chip microcontroller according to each phase IGBT unit judges
Motor whether there is ground fault, since each phase IGBT unit turn-on time t is strictly controlled within 10 μ s, even if motor is deposited
Each phase IGBT unit can't be caused to damage since the time t that each phase IGBT unit is switched on is very short in short trouble
It is bad, be conducive to extend the service life of frequency converter, and single-chip microcontroller directly with the output electric current of each phase IGBT unit be judge according to
According to ensure that the accuracy of judging result；Further, the single-chip microcontroller controls on the IGBT of each phase IGBT unit bridge Q1 successively
Turn-on time t, and the output electric current of each phase IGBT unit is successively measured by current sensor HL1 and is transferred to single-chip microcontroller respectively,
By single-chip microcontroller according to the output electric current of each phase IGBT unit judge motor each phase coil windings with the presence or absence of short trouble, have
Conducive to the position for more accurately judging electrical fault, convenience is provided for repair and maintenance personnel, improves repair and maintenance efficiency.
Frequency converter of the invention judges that a kind of mode of motor ground fault is as follows in frequency converter, is with frequency converter V phase
Example: when ground short circuit failure occurs for the coil windings of the V phase of motor, the phase (in the short circuit current that flows through can rapidly increase to
Short circuit current is converted into voltage signal by 2.5 times or more of frequency converter rated current, the current sensor HL1 in the phase, and will
Voltage signal is compared with the threshold voltage of setting, if the threshold value electricity of the voltage signal > setting of current sensor HL1 output
Pressure then exports low level signal to single-chip microcontroller, then single-chip microcontroller determines that ground short circuit failure occurs for motor, and triggers ground short circuit event
Barrier protection.Preferably, voltage signal can be compared compared with threshold voltage by comparator, can also be transferred to single-chip microcontroller
It is compared.It should be pointed out that the threshold voltage when bridge sequentially turns under each IGBT of IGBT unit, with IGBT unit
On each IGBT bridge simultaneously turn on or each IGBT under the threshold voltage that simultaneously turns on of bridge it is different.
Preferably, the value of the turn-on time t can realize by the timing control function of single-chip microcontroller itself, can also
To be realized by the time control circuit of peripheral hardware.
Preferably, as shown in Figure 1, the single-chip microcontroller includes output end DV+ and output end DV-, the light-emitting diodes of optocoupler PC1
Anode, the cathode of pipe are connected with output end DV+ and output end DV- respectively, anode, the cathode point of the light emitting diode of optocoupler PC2
It is not connected with output end DV- and output end DV+.Further, after the power transformation device powers on, single-chip microcontroller passes through output end DV+, defeated
Outlet DV- exports low level respectively, after relay actuation: the single-chip microcontroller exports high level by output end DV+ and passes through
Output end DV- exports low level, then optocoupler PC1 is connected, and bridge Q1 on IGBT is connected；The single-chip microcontroller is defeated by output end DV+
Low level and high level is exported by output end DV- out, then optocoupler PC2 is connected, and bridge Q2 is connected.
Preferably, the single-chip microcontroller can be the inherent structure of frequency converter, the i.e. included single-chip microcontroller of frequency converter, be also possible to
The single-chip microcontroller of peripheral hardware.
Preferably, as shown in Figure 1, the grid G of bridge Q1 passes through an a resistance R1 and optocoupler PC1 on each IGBT
Output end be connected, each IGBT on the grid G of bridge Q1 pass through a resistance R2 be connected with the emitter E of bridge Q1 on the IGBT,
The grid G of bridge Q2 is connected by a resistance R3 with the output end of an optocoupler PC2 under each IGBT, bridge Q2 under each IGBT
Grid G is connected by a resistance R4 with bridge emitter E under the IGBT；The emitter E of bridge Q1 on the IGBT of same IGBT unit
It is connected with the collector C of bridge Q2 under IGBT.The resistance R1, resistance R3 are driving resistance, and resistance R2, resistance R4 are electric discharge electricity
Resistance.
Preferably, as shown in Figure 1, the current sensor HL1 pass through respectively capacitor C1, capacitor C2 ground connection, capacitor C1 and
Capacitor C2 is decoupling capacitor.
As shown in Figure 1, being a kind of embodiment of frequency converter of the present invention.It should be noted that the optocoupler of embodiment middle finger
Which pin of PC1, optocoupler PC2, current sensor HL1 are an interface name, refer to an input of each chip or structure
Or output interface, not refer in particular to the pin which sequence is necessary for.
Frequency converter of the invention comprising IGBT circuit, charging resistor and the relay in parallel with charging resistor.
It is noted that the frequency converter further includes current rectifying and wave filtering circuit and the charge-discharge circuit including charging resistor,
These circuits can use the circuit structure of the prior art, and this will not be detailed here.
Frequency converter of the present invention includes the identical circuit of U, V, W three-phase, the circuit of every phase include optocoupler PC1, optocoupler PC2,
Resistance R1, resistance R2, resistance R3, resistance R4, IGBT unit, current sensor HL1, each IGBT unit includes bridge on IGBT
Bridge Q2 under Q1 and IGBT, wherein U phase IGBT unit is connected by a current sensor HL1 with the coil windings of the U phase of motor,
V phase IGBT unit is connected by a current sensor HL1 with the coil windings of the V phase of motor, and W phase IGBT unit passes through one
Current sensor HL1 is connected with the coil windings of the W phase of motor；Frequency converter of the invention further includes single-chip microcontroller.
As shown in Figure 1, the single-chip microcontroller includes output end DV+, the end output end DV- and I/O；Each optocoupler PC1's shines
Anode, the cathode of diode are connected with output end DV+, output end DV- respectively, and the 8th foot of each optocoupler PC1 is electric with VP+15
Source is connected, and the 5th foot of each optocoupler PC1 is connected with VP-10V power supply, and the 6th foot and the 7th foot of each optocoupler PC1 is connected and logical
A resistance R1 is crossed to be connected with the grid G of bridge Q1 on an IGBT；Anode, the cathode point of the light emitting diode of each optocoupler PC2
It is not connected with output end DV-, output end DV+, the 8th foot of each optocoupler PC2 is connected with VP+15V power supply, each optocoupler PC2
The 5th foot be connected with VP-10V power supply, the 6th foot and the 7th foot of each optocoupler PC2 are connected and pass through a resistance R3 and one
The grid G of bridge Q2 is connected under IGBT；The emitter E of bridge Q1 passes through bridge Q1 on the resistance R2 and IGBT on each IGBT
Grid G is connected, and the emitter E of bridge Q1 is connected with ground connection VPGND on each IGBT, and the collector C of bridge Q1 is equal on each IGBT
It is connected with main circuit of converter anode；The emitter E of bridge Q2 passes through bridge Q2 under the resistance R4 and IGBT under each IGBT
Grid G be connected, under each IGBT the emitter E of bridge Q2 with ground connection VDGND be connected, the emitter E of bridge Q2 under each IGBT
It is connected with the cathode of main circuit of converter；On the IGBT of same IGBT unit under the emitter E of bridge Q1 and IGBT bridge Q2 collection
Electrode C is connected, and on the IGBT of same IGBT unit under bridge Q1 and IGBT the node of bridge Q2 and current sensor HL1 the
6 feet are connected, and the 5th foot of each current sensor HL1 is connected to the motor, and the 1st foot of each current sensor HL1 passes through capacitor C1
It being grounded and is connected with -15V power supply, the 3rd foot of each current sensor HL1 is grounded by capacitor C2 and is connected with+15V power supply,
The 4th foot of each current sensor HL1 is connected with single-chip processor i/o end, the 2nd foot ground connection of each current sensor HL1.
Specifically, as shown in Figure 1, being carried out by taking the V circuitry phase of protection system of the present invention as an example to frequency converter of the invention
Explanation.
As shown in Figure 1, the anode of the light emitting diode of the optocoupler PC1, cathode respectively with the output end DV+ of single-chip microcontroller,
Output end DV- is connected, the anode of the light emitting diode of optocoupler PC2, cathode respectively with the output end DV- of single-chip microcontroller, output end DV+
It is connected, the anode of the light emitting diode of optocoupler PC1, cathode are connected with the 2nd of optocoupler PC1,3 feet respectively, and luminous the two of optocoupler PC2
The anode of pole pipe, cathode are connected with the 2nd of optocoupler PC2,3 feet respectively, the 8th foot of optocoupler PC1 and optocoupler PC2 with VP+15V electricity
Source be connected, the 5th foot of optocoupler PC1 and optocoupler PC2 are connected with VP-10V power supply, the 6th foot of optocoupler PC1 be connected with the 7th foot and
It is connected by resistance R1 with the grid G of bridge Q1 on IGBT, the 6th foot of optocoupler PC2 is connected with the 7th foot and by resistance R3 and IGBT
The grid G of lower bridge Q2 is connected；The emitter E of bridge Q1 is connected by resistance R2 with grid G on the IGBT, and be grounded VPGND
It is connected, the collector C of the upper bridge Q1 of IGBT is connected with the anode of main circuit of converter, under the emitter E and IGBT of the upper bridge Q1 of IGBT
The collector C of bridge Q2 is connected, and the emitter E of bridge Q2 is connected by resistance R4 with the grid G of bridge under IGBT under IGBT, and with ground connection
VDGND be connected, the emitter E of bridge Q2 is connected with the cathode of main circuit of converter under IGBT, the emitter E of the upper bridge Q1 of IGBT and
Node under IGBT between the collector C of bridge Q2 is connected with the 6th foot of current sensor HL1；The of the current sensor HL1
5 feet are connected with the coil windings of the V phase of motor, and the 3rd foot is connected with+15V power supply and is grounded by capacitor C1, the 1st foot and -15V
Power supply is connected and is grounded by capacitor C2, and the 4th foot is connected with the end I/O of single-chip microcontroller, the 2nd foot ground connection.The VP+15V power supply with
Ground connection VPGND is one group of power supply, and VP-10V power supply and ground connection VPGND are one group of power supplys, and the two is on the IGBT of V phase IGBT unit
Bridge Q1 provides driving power；The VD+15V power supply and ground connection VDGND are one group of power supplys, and VD-10V and ground connection VDGND are one group
Power supply, the two provide driving power for bridge Q2 under the IGBT of V phase IGBT unit；Wherein, VP, VD are mono- for distinguishing V phase IGBT
Character is distinguished in the identification of the driving power of the bridge up and down of member.
The course of work of protection system of the present invention will be illustrated by taking the V circuitry phase of frequency converter of the present invention as an example below.
After the frequency converter powers on, single-chip microcontroller exports low level by output end DV+, output end DV-, at this time optocoupler
PC1, optocoupler PC2 are held off, and IGBT unit is also held off, and after relay actuation, single-chip microcontroller passes through output in time t
It holds DV+ to export high level, 0 < t <, 10 μ s, and low level is persistently exported by output end DV-, then the light-emitting diodes of optocoupler PC1
Pipe shines, and so that optocoupler PC1 is opened the 6th, 7 feet and exports+15V voltage, opens bridge Q1 on IGBT, the upper bridge Q1 of IGBT by resistance R1
It opens and the DC bus P+ of main circuit of converter is connected with the coil windings of the V phase of motor；If the coil windings of the V phase of motor
There are ground short circuit failures, then trigger biggish short circuit current, and current sensor HL1 detects short circuit current and exports to monolithic
Machine, single-chip microcontroller according to short circuit current signal judges the coil windings of V phase, and there are ground short circuit failures, and ground fault is driven to alarm
Structure issues alarm signal, while triggering earth-fault protection cutting circuit.
Frequency converter of the invention, can be detected one by one or simultaneously by the above-mentioned course of work coil of U, V, W phase of motor around
Group whether there is ground short circuit failure, if it does not exist ground short circuit failure, then frequency converter normal Standby.
It, can change through the invention invention additionally discloses a kind of guard method for motor ground fault in frequency converter
Frequency device realizes that frequency converter includes IGBT circuit, charging resistor and the relay in parallel with charging resistor, and IGBT circuit includes U
Phase IGBT unit, V phase IGBT unit and W phase IGBT unit, every phase IGBT unit include bridge Q2 under bridge Q1 and IGBT on IGBT,
U phase IGBT unit, V phase IGBT unit and W phase IGBT unit respectively with the U phase volume coil windings of motor, the coil windings of V phase and
The coil windings of W phase are connected；
The frequency converter powers on and after tape relay actuation:
Successively make the IGBT unit of bridge Q1 and W phase on the IGBT of bridge Q1, V phase IGBT unit on the IGBT of U phase IGBT unit
IGBT on bridge Q1 turn-on time 10 μ s of t, 0 < t <, obtain U phase IGBT unit, V phase IGBT unit and W phase IGBT unit respectively
Output electric current, and judge the coils of the coil windings of U phase of motor, the coil windings of V phase and W phase respectively according to output electric current
Whether winding occurs ground short circuit failure；
Alternatively, making on the IGBT of U phase IGBT unit that bridge Q1 and W phase IGBT is mono- on the IGBT of bridge Q1, V phase IGBT unit simultaneously
Bridge Q1 turn-on time 10 μ s of t, 0 < t < on the IGBT of member obtains U phase IGBT unit, V phase IGBT unit in time t respectively
Judge whether motor occurs ground short circuit failure with the output electric current of W phase IGBT unit with the output electric current according to each phase；
Alternatively, making under the IGBT of U phase IGBT unit that bridge Q2 and W phase IGBT is mono- under the IGBT of bridge Q2, V phase IGBT unit simultaneously
Bridge Q2 turn-on time 10 μ s of t, 0 < t < under the IGBT of member obtains U phase IGBT unit, V phase IGBT unit in time t respectively
According to the output electric current of each phase judge whether that ground short circuit failure occurs with the output electric current of W phase IGBT unit.
Guard method for motor ground fault in frequency converter of the invention powers in frequency converter and relay is attracted
Afterwards, so that bridge Q1 on the IGBT of each phase IGBT unit is sequentially turned on time t, or make bridge Q1 on the IGBT of each phase IGBT unit while leading
Logical time t, or bridge Q2 under the IGBT of each phase IGBT unit is made to simultaneously turn on time t, and 0 < t <, 10 μ s, it is mono- to obtain each phase IGBT
The output electric current of member, the output electric current according to each phase IGBT unit judge motor with the presence or absence of ground fault, due to each phase IGBT
Unit turn-on time t is strictly controlled within 10 μ s, even if there are short troubles for motor, since each phase IGBT unit is switched on
Time t it is very short, therefore each phase IGBT unit can't be damaged, and single-chip microcontroller is directly with the defeated of each phase IGBT unit
Electric current is judgment basis out, ensure that the accuracy of judging result；Further, bridge on the IGBT for making each phase IGBT unit
Q1 sequentially turns on time t, and obtains the output electric current of each phase IGBT unit, and the output electric current according to each phase IGBT unit judges electricity
The coil windings of each phase of machine whether there is short trouble, is conducive to the position for more accurately judging electrical fault, is
Repair and maintenance personnel provide convenience, improve repair and maintenance efficiency；Guard method of the invention, easy to operate, judging result essence
Standard, and IGBT circuit will not be damaged, it can effectively extend the service life of frequency converter.
The above content is a further detailed description of the present invention in conjunction with specific preferred embodiments, and it cannot be said that
Specific implementation of the invention is only limited to these instructions.For those of ordinary skill in the art to which the present invention belongs, exist
Under the premise of not departing from present inventive concept, a number of simple deductions or replacements can also be made, all shall be regarded as belonging to of the invention
Protection scope.
Claims (8)
1. a kind of guard method for motor ground fault in frequency converter, frequency converter include IGBT circuit, charging resistor and
The relay in parallel with charging resistor, IGBT circuit include U phase IGBT unit, V phase IGBT unit and W phase IGBT unit, every phase
IGBT unit includes that bridge Q2, U phase IGBT unit, V phase IGBT unit and W phase IGBT unit are distinguished under bridge Q1 and IGBT on IGBT
It is connected with the coil windings of the coil windings of the U phase of motor, the coil windings of V phase and W phase；It is characterized by:
The frequency converter powers on and after relay actuation:
Successively make the IGBT of bridge Q1 and W phase IGBT unit on the IGBT of bridge Q1, V phase IGBT unit on the IGBT of U phase IGBT unit
10 μ s of upper bridge Q1 turn-on time t, 0 < t < obtains the output of U phase IGBT unit, V phase IGBT unit and W phase IGBT unit respectively
Electric current, and the output electric current according to each phase, judge the line of the coil windings of the U phase of motor, the coil windings of V phase and W phase respectively
Whether circle winding occurs ground short circuit failure；
Alternatively, making on the IGBT of U phase IGBT unit bridge Q1 and W phase IGBT unit on the IGBT of bridge Q1, V phase IGBT unit simultaneously
IGBT 10 μ s of upper bridge Q1 turn-on time t, 0 < t < obtains U phase IGBT unit, V phase IGBT unit and W phase in time t respectively
The output electric current of IGBT unit judges whether motor occurs ground short circuit failure according to the output electric current of each phase；
Alternatively, making under the IGBT of U phase IGBT unit bridge Q2 and W phase IGBT unit under the IGBT of bridge Q2, V phase IGBT unit simultaneously
10 μ s of bridge Q2 turn-on time t under IGBT, 0 < t < obtains U phase IGBT unit, V phase IGBT unit and W phase in time t respectively
The output electric current of IGBT unit judges whether motor occurs ground short circuit failure according to the output electric current of each phase.
2. a kind of frequency converter, which is characterized in that it is using the guarantor described in claim 1 for motor ground fault in frequency converter
Maintaining method；The grid G of bridge Q1 is connected with the output end of an optocoupler PC1 on each IGBT, bridge Q2 under each IGBT
Grid G is connected with the output end of an optocoupler PC2, the input terminal of optocoupler PC1 and optocoupler PC2 with the output end phase of single-chip microcontroller
Even, the node on the IGBT of U phase IGBT unit, V phase IGBT unit, W phase IGBT unit under bridge Q1 and IGBT between bridge Q2 is each logical
It crosses a current sensor HL1 to be connected with the coil windings of the coil windings of U phase of motor, the coil windings of V phase, W phase, electric current
Sensor HL1 is connected with single-chip microcontroller.
3. frequency converter according to claim 2, it is characterised in that: the single-chip microcontroller includes output end DV+ and output end
DV-, anode, the cathode of the light emitting diode of optocoupler PC1 are connected with output end DV+ and output end DV- respectively, the hair of optocoupler PC2
Anode, the cathode of optical diode are connected with output end DV- and output end DV+ respectively.
4. frequency converter according to claim 3, it is characterised in that: after the frequency converter powers on, single-chip microcontroller passes through output end
DV+, output end DV- export low level respectively, after relay actuation:
The single-chip microcontroller exports high level by output end DV+ and exports low level by output end DV-, then optocoupler PC1 is connected,
Bridge Q1 on IGBT is connected；
The single-chip microcontroller exports low level by output end DV+ and exports high level by output end DV-, then optocoupler PC2 is connected,
Bridge Q2 under IGBT is connected.
5. frequency converter according to claim 2, it is characterised in that: the grid G of bridge Q1 passes through one on each IGBT
Resistance R1 is connected with the output end of an optocoupler PC1, and the grid G of bridge Q1 passes through on a resistance R2 and IGBT on each IGBT
The emitter E of bridge is connected, and the grid G of bridge Q2 is connected by a resistance R3 with the output end of an optocoupler PC2 under each IGBT,
The grid G of bridge Q2 is connected by a resistance R4 with the emitter E of bridge under the IGBT under each IGBT；Same IGBT unit
The emitter E of the upper bridge Q1 of IGBT is connected with the collector C of bridge Q2 under IGBT.
6. frequency converter according to claim 2 or 5, it is characterised in that: the current sensor HL1 passes through capacitor respectively
C1, capacitor C2 ground connection.
7. frequency converter according to claim 2, it is characterised in that: the single-chip microcontroller includes output end DV+, output end DV-
With the end I/O；Anode, the cathode of the light emitting diode of each optocoupler PC1 are connected with output end DV+, output end DV- respectively, each
The 8th foot of optocoupler PC1 is connected with VP+15V power supply, and the 5th foot of each optocoupler PC1 is connected with VP-10V power supply, Mei Geguang
The 6th foot of coupling PC1 and the 7th foot are connected and are connected by a resistance R1 with the grid G of bridge Q1 on an IGBT；Each optocoupler
Anode, the cathode of the light emitting diode of PC2 are connected with output end DV-, output end DV+ respectively, and the 8th foot of each optocoupler PC2 is equal
It is connected with VP+15V power supply, the 5th foot of each optocoupler PC2 is connected with VP-10V power supply, the 6th foot and the 7th of each optocoupler PC2
Foot is connected and is connected by a resistance R3 with the grid G of bridge Q2 under an IGBT；The emitter E of bridge Q1 is logical on each IGBT
A resistance R2 is crossed to be connected with the grid G of bridge Q1 on the IGBT, on each IGBT the emitter E of bridge Q1 with ground connection VPGND phase
Even, the collector C of bridge Q1 is connected with the anode of main circuit of converter on each IGBT；The emitter E of bridge Q2 under each IGBT
Be connected with the grid G of bridge Q2 under the IGBT by a resistance R4, under each IGBT the emitter E of bridge Q2 with ground connection
VDGND is connected, and the emitter E of bridge Q2 is connected with the cathode of main circuit of converter under each IGBT；Same IGBT unit
The emitter E of the upper bridge Q1 of IGBT is connected with the collector C of bridge Q21 under IGBT, and on the IGBT of same IGBT unit bridge Q1 and
The node of bridge Q2 is connected with the 6th foot of a current sensor HL1 under IGBT, the 5th foot and motor of each current sensor HL1
It is connected, the 1st foot of each current sensor HL1 is grounded by capacitor C1 and is connected with -15V power supply, each current sensor HL1
The 3rd foot be grounded by capacitor C2 and be connected with+15V power supply, the 4th foot of each current sensor HL1 and the end I/O of single-chip microcontroller
It is connected, the 2nd foot ground connection of each current sensor HL1.
8. frequency converter according to claim 2, it is characterised in that: further include the ground fault alarm knot being connected with single-chip microcontroller
Structure, when single-chip microcontroller detects the ground short circuit failure of motor, ground fault alarm structure issues alarm signal；The protection system
Further include earth-fault protection, when single-chip microcontroller detects the ground short circuit failure of motor, trigger earth-fault protection,
Cut off circuit.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910308639.9A CN110148925A (en) | 2019-04-17 | 2019-04-17 | For the guard method of motor ground fault and frequency converter in frequency converter |
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| CN201910308639.9A CN110148925A (en) | 2019-04-17 | 2019-04-17 | For the guard method of motor ground fault and frequency converter in frequency converter |
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