CN115694136B - Frequency converter protection system capable of reducing loss and frequency converter - Google Patents
Frequency converter protection system capable of reducing loss and frequency converter Download PDFInfo
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- CN115694136B CN115694136B CN202211455113.1A CN202211455113A CN115694136B CN 115694136 B CN115694136 B CN 115694136B CN 202211455113 A CN202211455113 A CN 202211455113A CN 115694136 B CN115694136 B CN 115694136B
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The invention relates to the technical field of frequency converters, in particular to a frequency converter protection system for reducing loss and a frequency converter, wherein the protection system comprises: the load is externally connected with a power detector for detecting the running power of the load; the frequency converter is connected with the load and used for adjusting the voltage and frequency of the output power supply transmitted to the load according to the running power of the load; the heat dissipation device is connected with the frequency converter and is used for adjusting the temperature of the environment where the frequency converter is positioned to a corresponding value by using a preset rotating speed; the output power supply is connected with the frequency converter and used for conveying voltage and frequency with corresponding values to the frequency converter; and the central control processor is used for controlling the frequency converter to adjust the voltage and frequency of the output power supply to the load to corresponding values according to the running power of the load. According to the invention, the rotating speed of the fan is regulated by the switching times of the IGBT in a single preset period and the temperature of the environment, so that the protection efficiency of the protection system is improved.
Description
Technical Field
The invention relates to the technical field of frequency converters, in particular to a frequency converter protection system capable of reducing loss and a frequency converter.
Background
The frequency converter is a power control device which controls the alternating current motor by changing the frequency of a working power supply of the motor by applying a frequency conversion technology and a microelectronic technology. The frequency converter can realize a plurality of control means such as soft start, multistage speed, low-speed high-efficiency operation of motor equipment, and the parameter of accessible adjustment frequency converter reaches different demand effects under different operating mode conditions.
In the prior art, when the existing frequency converter is used, the control circuit board on the frequency converter is generally conducted through the switch controller, so that the motor is controlled, however, in the process from starting to conducting and running of the control circuit board, part of electric energy in the control circuit board is dispersed in the form of heat energy and mechanical energy, so that the output voltage loss of the frequency converter is increased, and the use cost is increased.
Chinese patent publication No.: CN113708598A discloses a switching device for reducing output voltage loss of a frequency converter, the device comprises a frequency converter control circuit board, the frequency converter control circuit board is electrically connected with a switch controller through a wire, the switch controller is electrically connected with a radiator fan through a wire, the radiator fan is located above a radiator fin, the radiator fin is arranged on the upper side of the frequency converter control circuit board, and a heat conducting component is arranged on the radiator fin.
The prior art cannot greatly cause the increase of the loss of the frequency converter caused by the excessive switching times of the IGBT according to the change amplitude of the voltage output to the load by the frequency converter.
Disclosure of Invention
In order to achieve the above-mentioned objective, the present invention provides a protection system for a frequency converter and a frequency converter for reducing loss, which are used to overcome the problem of low protection efficiency for the frequency converter caused by the increased loss of the frequency converter due to excessive switching times of IGBTs in the prior art.
In one aspect, the present invention provides a reduced loss frequency converter protection system, comprising:
the load is externally connected with a power detector for detecting the running power of the load;
the frequency converter is connected with the load and used for adjusting the voltage and frequency of the output power supply transmitted to the load according to the running power of the load; the frequency converter is internally provided with a counter for recording the switching times of the IGBT and a temperature detector for detecting the temperature of the IGBT;
the heat dissipation device is connected with the frequency converter and used for adjusting the temperature of the environment where the frequency converter is positioned, and comprises a fan which is used for adjusting the temperature of the environment where the frequency converter is positioned to a corresponding value by using a preset rotating speed;
the output power supply is connected with the frequency converter and used for conveying voltage and frequency with corresponding values to the frequency converter;
the central control processor is respectively connected with the load, the frequency converter and corresponding parts in the heat dissipation device, and is used for controlling the frequency converter to adjust the voltage and the frequency of the output power supply to the load to corresponding values according to the running power of the load, judging whether the IGBT has loss increase risk according to the voltage and the frequency adjusted by the frequency converter, and adjusting the rotating speed of the fan to corresponding values according to the switching times of the IGBT in a single preset period and the temperature and the voltage of the IGBT in the preset period when judging that the loss increase risk exists in the IGBT.
Further, the central control processor controls the power detector to detect the running power P of the load so as to judge whether to adjust the voltage and the frequency of the frequency converter to the load to corresponding values according to the P, the central control processor is provided with preset power P0,
if P is less than P0, the central control processor judges that the actual running power of the load does not meet a preset standard, the central control processor calculates a difference value delta P between P0 and P, and adjusts the voltage output by the frequency converter to the load to a corresponding value according to delta P, and delta P=P0-P is set;
if p=p0, the central control processor determines that the actual running power of the load meets a preset standard;
if P is more than P0, the central control processor judges that the actual running power of the load does not meet a preset standard, the IGBT has the risk of loss increase, and the central control processor controls the counter to count the switching times of the IGBT in a single preset period and controls the temperature detector to detect the temperature of the environment where the IGBT is located so as to judge whether the rotating speed of the fan is regulated to a corresponding value.
Further, the central control processor adjusts the voltage output from the frequency converter to the load to a corresponding value according to the difference DeltaP between the preset power P0 and the running power P of the load under a first preset condition, the central control processor is provided with a first preset power difference DeltaP 1 and a second preset power difference DeltaP 2, a first preset voltage adjustment coefficient alpha 1 and a second preset voltage adjustment coefficient alpha 2, wherein DeltaP 1 < DeltaP2, 1 < alpha 2 < 1.4,
if delta P is less than or equal to delta P1, the central control processor judges that the actual running power of the load meets a preset standard;
if delta P1 is less than delta P2, the central control processor judges that the actual running power of the load does not meet a preset standard, and the central control processor uses alpha 1 to regulate the voltage output to the load by the frequency converter;
if delta P > -delta P2, the central control processor judges that the actual running power of the load does not meet a preset standard, and the central control processor uses alpha 2 to regulate the voltage output by the frequency converter to the load;
the central control processor marks the voltage output to the load by the frequency converter regulated by the alpha i as U ', and sets U' =U0×alpha i, wherein i=1, 2, and U0 is the initial voltage output to the load by the frequency converter;
the first preset condition is that the central control processor determines that the actual running power P of the load is smaller than preset power P0.
Further, the central control processor repeatedly adjusts the operation power of the load, and records the actual operation power of the adjusted load as P ', if the adjusted voltage U' is greater than a first preset critical voltage Uamax and P '< P0 set in the central control processor, the central control processor selects a corresponding frequency according to a difference delta Pa between P0 and P', the frequency of the frequency converter output to the load is adjusted to a corresponding value, the central control processor is provided with a first frequency adjustment coefficient beta 1, a second frequency adjustment coefficient beta 2 and a third frequency adjustment coefficient beta 3, wherein, 1.1 < beta 1 < beta 2 < beta 3 < 1.5,
if delta Pa is less than or equal to delta P1, the central control processor uses beta 1 to adjust the frequency of the frequency converter output to the load to a corresponding value;
if delta P1 < [ delta ] Pa is less than or equal to delta P2, the central control processor uses beta 2 to adjust the frequency of the frequency converter output to the load to a corresponding value;
if DeltaPa > DeltaP2, the central control processor uses beta 3 to adjust the frequency of the frequency converter output to the load to a corresponding value;
the central control processor marks the frequency of the frequency converter output to the load after being regulated by beta j as f ', wherein f' =f0×beta j, j=1, 2,3, f0 is set as the initial frequency of the frequency converter output to the load.
Further, the central control processor compares U' with a second preset critical voltage Ubmax set in the central control processor under a second preset condition, judges whether the IGBT has a loss increase risk according to a comparison result, sets Ubmax to be larger than Uamax,
if U' > Ubmax, the central control processor judges that the IGBT has the risk of loss increase;
if U' is less than or equal to Ubmax, the central control processor judges that the IGBT meets the preset requirement;
and the second preset condition is that the central control processor judges that the regulated voltage U 'output to the load by the frequency converter meets U' > Uamax.
Further, the central control processor acquires historical data of the operating parameters of the IGBT under a third preset condition to calculate a risk evaluation value E of the IGBT, wherein the operating parameters comprise switching times M in a single period t, voltage Ug flowing through the IGBT and frequency f flowing through the IGBT, and the operating parameters are set
Wherein a is a first weight coefficient, and a=0.4v is set -1 B is a second weight coefficient, b=0.3 Hz is set -1 C is a third weight coefficient, c=0.3 s is set -1 ；
And the third preset condition is that the central control processor judges that the regulated voltage U 'output to the load by the frequency converter meets U' > Ubmax > Uamax.
Further, the central control processor adjusts the rotating speed of the fan to a corresponding value according to the risk evaluation value E of the IGBT under the third preset condition, the central control processor is provided with a first preset risk evaluation standard E1, a second preset risk evaluation standard E2, a first rotating speed adjustment coefficient gamma 1, a second rotating speed adjustment coefficient gamma 2 and a third rotating speed adjustment coefficient gamma 3, wherein E1 is less than E2,1 is less than gamma 1 and less than gamma 2 is less than gamma 3 and less than 1.6,
if E is less than or equal to E1, the central control processor uses gamma 1 to adjust the rotating speed of the fan to a corresponding value;
if E1 is more than E and less than or equal to E2, the central control processor uses gamma 2 to regulate the rotating speed of the fan;
if E > E2, the central control processor uses gamma 3 to adjust the rotating speed of the fan to a corresponding value;
the central control processor marks the rotating speed of the fan regulated by gamma k as V ', and sets V' =V0×gamma k, wherein k=1, 2,3 and V0 are the initial rotating speeds of the fan.
Further, the central control processor controls the temperature detector to detect the temperature T of the IGBT when judging that the IGBT has the risk of loss increase, corrects the rotating speed of the fan according to the detected result, and is provided with a first preset standard temperature T1, a second preset standard temperature T2, a first rotating speed correction coefficient epsilon 1 and a second rotating speed correction coefficient epsilon 2, wherein T1 is less than T2, epsilon 1 is less than epsilon 2 and epsilon 2 is less than 1.7,
if T is less than or equal to T1, the central control processor judges that the rotating speed of the fan accords with a preset standard cone;
if T1 is more than T and less than or equal to T2, the central control processor corrects the rotating speed of the fan by using epsilon 1;
if T is more than T2, the central control processor corrects the rotating speed of the fan by using epsilon 2;
the central control processor marks the rotation speed of the fan regulated by epsilon e as V ', wherein e=1, 2, and V ' =V ' ×epsilon e is set.
Further, the central control processor calculates the running power Pm of the fan after correcting the rotating speed of the fan according to the comparison result after comparing the temperature T of the IGBT with each preset standard temperature, determines whether to reduce the rotating speed of the fan according to the comparison result by comparing the running power Pm of the fan with the preset running power Ph set for the fan in the central control processor,
if Pm is less than or equal to Ph, the central control processor judges that the running power of the fan meets the standard;
if Pm > Ph, the central control processor judges to reduce the rotating speed of the fan so as to enable the operating power of the fan to meet the standard.
In another aspect, the present invention also provides a frequency converter based on the protection system of any one of claims 1-9, comprising:
a main body in which a counter and a temperature detector are provided for adjusting the voltage and frequency of the output power supplied to the load; the counter is used for recording the switching times of the IGBT; the temperature detector is used for detecting the temperature of the IGBT;
the heat dissipation device is connected with the frequency converter and used for adjusting the temperature of the environment where the frequency converter is located, and the heat dissipation device comprises a fan and is used for adjusting the temperature of the environment where the frequency converter is located to a corresponding value by using a preset rotating speed.
Compared with the prior art, the method has the beneficial effects that the voltage and the frequency of the load transmitted by the frequency converter to the load are regulated to the corresponding values by detecting the running power of the load, and the load can be prevented from overvoltage and overcurrent by regulating the voltage and the frequency of the load, so that the loss of the frequency converter is effectively reduced; according to the invention, the switching times of the IGBT in a single preset period are counted, the temperature of the environment where the IGBT is located is detected to regulate the rotating speed of the fan, and the loss of the IGBT can be effectively reduced when the switching times and the temperature of the IGBT are too high by regulating the rotating speed of the fan, so that the protection efficiency of the protection system for the frequency converter is effectively improved.
Further, the invention judges whether the operating power of the load accords with the standard or not by comparing the operating power P of the load with the preset power, and adjusts the condition that the load power does not accord with the standard in time by detecting the operating power of the load, thereby avoiding the damage of components in the frequency converter caused by the failure of a circuit due to the untimely detection, and indirectly playing a role in protecting the frequency converter.
Furthermore, the central control processor is provided with a plurality of preset power differences and a plurality of voltage regulation coefficients, the delta P is compared with the preset power differences, the voltage which is transmitted to the load by the frequency converter is regulated to a corresponding value according to the comparison result, and the voltage which flows through the load is regulated to ensure that the whole circuit is smooth, so that the frequency converter is prevented from being damaged due to the overvoltage problem, the frequency converter is protected, and the protection efficiency of the protection system for the frequency converter is further improved.
Further, the central control processor is provided with the first preset critical voltage Uamax, when the central control processor can not adjust the operation power to the corresponding value after repeatedly adjusting the operation power of the load, the frequency of the frequency converter output to the load is adjusted according to the comparison result by comparing the first preset critical voltage with each preset power difference value so as to adjust the operation power of the load to the corresponding value, and the frequency is adjusted so as to enable the operation power of the load to meet the standard, so that the load operates normally, the frequency converter is protected, and the protection efficiency of the protection system for the frequency converter is further improved.
Further, the central control processor is provided with the second preset critical voltage Ubmax, whether the IGBT has the loss increase risk or not is judged according to the comparison result by comparing the voltage after repeated adjustment with the second preset critical voltage, and the IGBT is prevented from being damaged due to overlarge voltage caused by untimely judgment by evaluating the state of the IGBT of the frequency converter, so that the protection efficiency of the protection system is effectively improved.
Further, the central control processor is provided with a plurality of preset risk assessment standards and a plurality of rotation speed adjustment coefficients, the rotation speed of the fan is adjusted by comparing the risk assessment value of the IGBT with each preset risk assessment standard, the temperature of the IGBT is reduced by increasing the rotation speed of the fan, so that the loss of the IGBT is reduced, and the protection efficiency of the protection system for the frequency converter is effectively improved.
Further, the central control processor is provided with the preset running power Ph for the fan, whether the rotating speed of the fan meets the standard is judged by comparing the corrected running power Pm with the preset running power Ph, and if the corrected running power is larger than the preset running power, the fan is protected by reducing the rotating speed of the fan, so that the reasonable running of the device in the protection system is effectively ensured, the damage to the device is avoided, and the protection efficiency of the protection system for the frequency converter is further improved.
Drawings
Fig. 1 is a schematic structural diagram of a frequency converter protection system for reducing loss according to an embodiment of the present invention;
FIG. 2 is a flow chart of adjusting the voltage output from the inverter to the load to a corresponding value according to the power difference ΔP in the embodiment of the present invention;
FIG. 3 is a flow chart of adjusting the frequency of the output of the frequency converter to the load to a corresponding value according to the power difference ΔPa in the embodiment of the invention;
fig. 4 is a flowchart of adjusting the rotation speed of the fan to a corresponding value according to the risk assessment value of the IGBT according to the embodiment of the present invention.
Detailed Description
In order that the objects and advantages of the invention will become more apparent, the invention will be further described with reference to the following examples; it should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are merely for explaining the technical principles of the present invention, and are not intended to limit the scope of the present invention.
It should be noted that, in the description of the present invention, terms such as "upper," "lower," "left," "right," "inner," "outer," and the like indicate directions or positional relationships based on the directions or positional relationships shown in the drawings, which are merely for convenience of description, and do not indicate or imply that the apparatus or elements must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.
Furthermore, it should be noted that, in the description of the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be either fixedly connected, detachably connected, or integrally connected, for example; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention can be understood by those skilled in the art according to the specific circumstances.
Fig. 1 is a schematic structural diagram of a loss-reducing protection system for a frequency converter according to an embodiment of the invention, where the loss-reducing protection system for a frequency converter includes:
a load (not shown in the figure), which is externally connected with a power detector (not shown in the figure) for detecting the operation power of the load;
the frequency converter is connected with the load and used for adjusting the voltage and frequency of the output power supply transmitted to the load according to the running power of the load; a counter for recording the switching times of the IGBT and a temperature detector (not shown in the figure) for detecting the temperature of the IGBT are arranged in the frequency converter;
the heat dissipation device (not shown in the figure) is connected with the frequency converter and used for adjusting the temperature of the environment where the frequency converter is positioned, and the heat dissipation device comprises a fan and is used for adjusting the temperature of the environment where the frequency converter is positioned to a corresponding value by using a preset rotating speed;
the output power supply is connected with the frequency converter and used for conveying voltage and frequency with corresponding values to the frequency converter;
and the central control processor (not shown in the figure) is respectively connected with the load, the frequency converter and corresponding parts in the heat dissipation device, and is used for controlling the frequency converter to adjust the voltage and the frequency of the output power supply to the load to corresponding values according to the running power of the load, judging whether the IGBT has the loss increase risk according to the voltage and the frequency adjusted by the frequency converter, and adjusting the rotating speed of the fan to corresponding values according to the switching times of the IGBT in a single preset period and the temperature and the voltage of the IGBT in the preset period when judging that the loss increase risk exists.
Specifically, the central control processor controls the power detector to detect the running power P of the load so as to judge whether to adjust the voltage and the frequency of the frequency converter to the load to corresponding values according to the P, the central control processor is provided with preset power P0,
if P is less than P0, the central control processor judges that the actual running power of the load does not meet a preset standard, the central control processor calculates a difference value delta P between P0 and P, and adjusts the voltage output by the frequency converter to the load to a corresponding value according to delta P, and delta P=P0-P is set;
if p=p0, the central control processor determines that the actual running power of the load meets a preset standard;
if P is more than P0, the central control processor judges that the actual running power of the load does not meet a preset standard, the IGBT has the risk of loss increase, and the central control processor controls the counter to count the switching times of the IGBT in a single preset period and controls the temperature detector to detect the temperature of the environment where the IGBT is located so as to judge whether the rotating speed of the fan is regulated to a corresponding value.
According to the invention, whether the operating power of the load meets the standard is judged by comparing the operating power P of the load with the preset power, and the condition that the load power does not meet the standard is timely regulated by detecting the operating power of the load, so that the damage of components in the frequency converter caused by the failure of a circuit due to the untimely detection is avoided, and the frequency converter is indirectly protected.
Referring to fig. 2, which is a flowchart of the present invention for adjusting the voltage of the inverter output to the load to a corresponding value according to the power difference Δp, the central control processor adjusts the voltage of the inverter output to the load to a corresponding value according to the difference Δp between the preset power P0 and the operating power P of the load under a first preset condition, wherein the central control processor is provided with a first preset power difference Δp1 and a second preset power difference Δp2, a first preset voltage adjustment coefficient α1 and a second preset voltage adjustment coefficient α2, wherein Δp1 < [ Δp2 ], 1 < α1 < α2 < 1.4,
if delta P is less than or equal to delta P1, the central control processor judges that the actual running power of the load meets a preset standard;
if delta P1 is less than delta P2, the central control processor judges that the actual running power of the load does not meet a preset standard, and the central control processor uses alpha 1 to regulate the voltage output to the load by the frequency converter;
if delta P > -delta P2, the central control processor judges that the actual running power of the load does not meet a preset standard, and the central control processor uses alpha 2 to regulate the voltage output by the frequency converter to the load;
the central control processor marks the voltage output to the load by the frequency converter regulated by the alpha i as U ', and sets U' =U0×alpha i, wherein i=1, 2, and U0 is the initial voltage output to the load by the frequency converter;
the first preset condition is that the central control processor determines that the actual running power P of the load is smaller than preset power P0.
The central control processor is provided with a plurality of preset power differences and a plurality of voltage regulation coefficients, the delta P is compared with the preset power differences, the voltage which is transmitted to the load by the frequency converter is regulated to a corresponding value according to the comparison result, and the voltage which flows through the load is regulated to enable the whole circuit to be smooth, so that the frequency converter is prevented from being damaged due to overvoltage, the frequency converter is protected, and the protection efficiency of the protection system for the frequency converter is further improved.
Referring to fig. 3, which is a flowchart of the embodiment of the invention, according to the power difference Δpa, the central control processor repeatedly adjusts the operating power of the load, and records the actual operating power of the adjusted load as P ', if the adjusted voltage U' is greater than a first preset critical voltage Uamax and P '< P0 set in the central control processor, the central control processor selects a corresponding frequency according to the difference Δpa between P0 and P', adjusts the frequency of the frequency converter output to the load to a corresponding value, the central control processor is provided with a first frequency adjustment coefficient β1, a second frequency adjustment coefficient β2 and a third frequency adjustment coefficient β3, wherein β1 is greater than 1.1 and β2 is less than β3 and less than 1.5,
if delta Pa is less than or equal to delta P1, the central control processor uses beta 1 to adjust the frequency of the frequency converter output to the load to a corresponding value;
if delta P1 < [ delta ] Pa is less than or equal to delta P2, the central control processor uses beta 2 to adjust the frequency of the frequency converter output to the load to a corresponding value;
if DeltaPa > DeltaP2, the central control processor uses beta 3 to adjust the frequency of the frequency converter output to the load to a corresponding value;
the central control processor marks the frequency of the frequency converter output to the load after being regulated by beta j as f ', wherein f' =f0×beta j, j=1, 2,3, f0 is set as the initial frequency of the frequency converter output to the load.
When the central control processor is provided with a first preset critical voltage Uamax and the running power of the load cannot be regulated to a corresponding value after the running power of the load is regulated repeatedly, the frequency of the frequency converter output to the load is regulated to the corresponding value according to the comparison result by comparing the first preset critical voltage with each preset power difference value, and the running power of the load is regulated to meet the standard by regulating the frequency, so that the load runs normally, the frequency converter is protected, and the protection efficiency of the protection system for the frequency converter is further improved.
Specifically, the central control processor compares U' with a second preset critical voltage Ubmax set in the central control processor under a second preset condition, judges whether the IGBT has a loss increase risk according to a comparison result, sets Ubmax to be larger than Uamax,
if U' > Ubmax, the central control processor judges that the IGBT has the risk of loss increase;
if U' is less than or equal to Ubmax, the central control processor judges that the IGBT meets the preset requirement;
and the second preset condition is that the central control processor judges that the regulated voltage U 'output to the load by the frequency converter meets U' > Uamax.
The central control processor is provided with the second preset critical voltage Ubmax, the voltage after repeated adjustment is compared with the second preset critical voltage, whether the IGBT has loss increase risk or not is judged according to the comparison result, and the state of the IGBT of the frequency converter is evaluated, so that the damage to the IGBT caused by excessive voltage due to untimely judgment is avoided, and the protection efficiency of the protection system for the frequency converter is effectively improved.
Specifically, the central control processor acquires historical data of the operating parameters of the IGBT under a third preset condition to calculate a risk evaluation value E of the IGBT, where the operating parameters include the switching times M in a single period t, the voltage Ug flowing through the IGBT, and the frequency f flowing through the IGBT, and sets
Wherein a is a first weight coefficient, and a=0.4v is set -1 B is a second weight coefficient, b=0.3 Hz is set -1 C is a third weight coefficient, c=0.3 s is set -1 ；
And the third preset condition is that the central control processor judges that the regulated voltage U 'output to the load by the frequency converter meets U' > Ubmax > Uamax.
Specifically, the central control processor adjusts the rotating speed of the fan to a corresponding value according to the risk evaluation value E of the IGBT under the third preset condition, the central control processor is provided with a first preset risk evaluation standard E1, a second preset risk evaluation standard E2, a first rotating speed adjustment coefficient gamma 1, a second rotating speed adjustment coefficient gamma 2 and a third rotating speed adjustment coefficient gamma 3, wherein E1 is less than E2,1 is less than gamma 1 and gamma 2 is less than gamma 3 and less than 1.6,
if E is less than or equal to E1, the central control processor uses gamma 1 to adjust the rotating speed of the fan to a corresponding value;
if E1 is more than E and less than or equal to E2, the central control processor uses gamma 2 to regulate the rotating speed of the fan;
if E > E2, the central control processor uses gamma 3 to adjust the rotating speed of the fan to a corresponding value;
the central control processor marks the rotating speed of the fan regulated by gamma k as V ', and sets V' =V0×gamma k, wherein k=1, 2,3 and V0 are the initial rotating speeds of the fan.
The central control processor is provided with a plurality of preset risk assessment standards and a plurality of rotation speed adjustment coefficients, the rotation speed of the fan is adjusted by comparing the risk assessment value of the IGBT with each preset risk assessment standard, the temperature of the IGBT is reduced by increasing the rotation speed of the fan, so that the loss of the IGBT is reduced, and the protection efficiency of the protection system for the frequency converter is effectively improved.
Referring to fig. 4, which is a flowchart of adjusting the rotation speed of the fan to a corresponding value according to the risk assessment value of the IGBT according to the embodiment of the invention, the central control processor controls the temperature detector to detect the temperature T of the IGBT when determining that the IGBT has increased risk of loss, corrects the rotation speed of the fan according to the detected result, and is provided with a first preset standard temperature T1, a second preset standard temperature T2, a first rotation speed correction coefficient epsilon 1 and a second rotation speed correction coefficient epsilon 2, wherein T1 is less than T2, epsilon 1 is less than epsilon 1.7,
if T is less than or equal to T1, the central control processor judges that the rotating speed of the fan accords with a preset standard cone;
if T1 is more than T and less than or equal to T2, the central control processor corrects the rotating speed of the fan by using epsilon 1;
if T is more than T2, the central control processor corrects the rotating speed of the fan by using epsilon 2;
the central control processor marks the rotation speed of the fan regulated by epsilon e as V ', wherein e=1, 2, and V ' =V ' ×epsilon e is set.
Specifically, the central control processor calculates the running power Pm of the fan after correcting the rotating speed of the fan according to the comparison result after comparing the temperature T of the IGBT with each preset standard temperature, determines whether to reduce the rotating speed of the fan according to the comparison result by comparing the running power Pm of the fan with the preset running power Ph set for the fan in the central control processor,
if Pm is less than or equal to Ph, the central control processor judges that the running power of the fan meets the standard;
if Pm > Ph, the central control processor judges to reduce the rotating speed of the fan so as to enable the operating power of the fan to meet the standard.
The central control processor is provided with the preset operating power Ph for the fan, the corrected operating power Pm is compared with the preset operating power Ph to judge whether the rotating speed of the fan meets the standard, if the corrected operating power is larger than the preset operating power, the fan is protected by reducing the rotating speed of the fan, the reasonable operation of the device in the protection system is effectively ensured, the damage to the device is avoided, and the protection efficiency of the protection system for the frequency converter is further improved.
In another aspect, the present invention also provides a frequency converter based on the protection system of any one of claims 1-9, comprising:
a main body in which a counter and a temperature detector are provided for adjusting the voltage and frequency of the output power supplied to the load; the counter is used for recording the switching times of the IGBT; the temperature detector is used for detecting the temperature of the IGBT;
the heat dissipation device is connected with the frequency converter and used for adjusting the temperature of the environment where the frequency converter is located, and the heat dissipation device comprises a fan and is used for adjusting the temperature of the environment where the frequency converter is located to a corresponding value by using a preset rotating speed.
Thus far, the technical solution of the present invention has been described in connection with the preferred embodiments shown in the drawings, but it is easily understood by those skilled in the art that the scope of protection of the present invention is not limited to these specific embodiments. Equivalent modifications and substitutions for related technical features may be made by those skilled in the art without departing from the principles of the present invention, and such modifications and substitutions will be within the scope of the present invention.
The foregoing description is only of the preferred embodiments of the invention and is not intended to limit the invention; various modifications and variations of the present invention will be apparent to those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A loss-reducing frequency converter protection system, comprising:
the load is externally connected with a power detector for detecting the running power of the load;
the frequency converter is connected with the load and used for adjusting the voltage and frequency of the output power supply transmitted to the load according to the running power of the load; the frequency converter is internally provided with a counter for recording the switching times of the IGBT and a temperature detector for detecting the temperature of the IGBT;
the heat dissipation device is connected with the frequency converter and used for adjusting the temperature of the environment where the frequency converter is positioned, and comprises a fan which is used for adjusting the temperature of the environment where the frequency converter is positioned to a corresponding value by using a preset rotating speed;
the output power supply is connected with the frequency converter and used for conveying voltage and frequency with corresponding values to the frequency converter;
the central control processor is respectively connected with the load, the frequency converter and corresponding parts in the heat dissipation device, and is used for controlling the frequency converter to adjust the voltage and the frequency of the output power supply to the load to corresponding values according to the running power of the load, judging whether the IGBT has loss increase risk according to the voltage and the frequency adjusted by the frequency converter, and adjusting the rotating speed of the fan to corresponding values according to the switching times of the IGBT in a single preset period and the temperature and the voltage of the IGBT in the preset period when judging that the loss increase risk exists in the IGBT.
2. The system of claim 1, wherein the central processor controls the power detector to detect the operating power P of the load to determine whether to adjust the voltage and frequency of the frequency converter to the load to corresponding values according to P, the central processor has a preset power P0,
if P is less than P0, the central control processor judges that the actual running power of the load does not meet a preset standard, the central control processor calculates a difference value delta P between P0 and P, and adjusts the voltage output by the frequency converter to the load to a corresponding value according to delta P, and delta P=P0-P is set;
if p=p0, the central control processor determines that the actual running power of the load meets a preset standard;
if P is more than P0, the central control processor judges that the actual running power of the load does not meet a preset standard, the IGBT has the risk of loss increase, and the central control processor controls the counter to count the switching times of the IGBT in a single preset period and controls the temperature detector to detect the temperature of the environment where the IGBT is located so as to judge whether the rotating speed of the fan is regulated to a corresponding value.
3. The system according to claim 2, wherein the central control processor adjusts the voltage output from the frequency converter to the load to a corresponding value according to a difference Δp between the preset power P0 and the operating power P of the load under a first preset condition, the central control processor is provided with a first preset power difference Δp1 and a second preset power difference Δp2, a first preset voltage adjustment coefficient α1 and a second preset voltage adjustment coefficient α2, wherein Δp1 < [ Δp2 ], 1 < α1 < α2 < 1.4,
if delta P is less than or equal to delta P1, the central control processor judges that the actual running power of the load meets a preset standard;
if delta P1 is less than delta P2, the central control processor judges that the actual running power of the load does not meet a preset standard, and the central control processor uses alpha 1 to regulate the voltage output to the load by the frequency converter;
if delta P > -delta P2, the central control processor judges that the actual running power of the load does not meet a preset standard, and the central control processor uses alpha 2 to regulate the voltage output by the frequency converter to the load;
the central control processor marks the voltage output to the load by the frequency converter regulated by the alpha i as U ', and sets U' =U0×alpha i, wherein i=1, 2, and U0 is the initial voltage output to the load by the frequency converter;
the first preset condition is that the central control processor determines that the actual running power P of the load is smaller than preset power P0.
4. The system of claim 3, wherein the central control processor repeatedly adjusts the operating power of the load and records the actual operating power of the load as P ', if the adjusted voltage U' is greater than a first preset critical voltage Uamax and P '< P0 set in the central control processor, the central control processor selects a corresponding frequency according to a difference Δpa between P0 and P', adjusts the frequency of the frequency output to the load to a corresponding value, the central control processor is provided with a first frequency adjustment coefficient β1, a second frequency adjustment coefficient β2 and a third frequency adjustment coefficient β3, wherein 1.1 < β1 < β2 < β3 < 1.5,
if delta Pa is less than or equal to delta P1, the central control processor uses beta 1 to adjust the frequency of the frequency converter output to the load to a corresponding value;
if delta P1 < [ delta ] Pa is less than or equal to delta P2, the central control processor uses beta 2 to adjust the frequency of the frequency converter output to the load to a corresponding value;
if DeltaPa > DeltaP2, the central control processor uses beta 3 to adjust the frequency of the frequency converter output to the load to a corresponding value;
the central control processor marks the frequency of the frequency converter output to the load after being regulated by beta j as f ', wherein f' =f0×beta j, j=1, 2,3, f0 is set as the initial frequency of the frequency converter output to the load.
5. The system of claim 4, wherein the central processor compares U' with a second preset threshold voltage Ubmax set in the central processor under a second preset condition, determines whether the IGBT has a loss increase risk according to the comparison result, sets Ubmax > Uamax,
if U' > Ubmax, the central control processor judges that the IGBT has the risk of loss increase;
if U' is less than or equal to Ubmax, the central control processor judges that the IGBT meets the preset requirement;
and the second preset condition is that the central control processor judges that the regulated voltage U 'output to the load by the frequency converter meets U' > Uamax.
6. The loss-reduced frequency converter protection system according to claim 5, wherein the central control processor obtains history data of the IGBT operating parameters including the number of switching times M, the voltage Ug across the IGBT, and the frequency f across the IGBT in a single period t under a third preset condition to calculate a risk evaluation value E of the IGBT, and sets
Wherein a is a first weight coefficient, and a=0.4v is set -1 B is a second weight coefficient, b=0.3 Hz is set -1 C is a third weight coefficient, c=0.3 s is set -1 ；
And the third preset condition is that the central control processor judges that the regulated voltage U 'output to the load by the frequency converter meets U' > Ubmax > Uamax.
7. The reduced-loss frequency converter protection system according to claim 6, wherein the central control processor adjusts the rotational speed of the fan to a corresponding value according to the risk assessment value E of the IGBT under the third preset condition, the central control processor is provided with a first preset risk assessment criterion E1, a second preset risk assessment criterion E2, a first rotational speed adjustment coefficient γ1, a second rotational speed adjustment coefficient γ2, and a third rotational speed adjustment coefficient γ3, wherein E1 < E2,1 < γ1 < γ2 < γ3 < 1.6,
if E is less than or equal to E1, the central control processor uses gamma 1 to adjust the rotating speed of the fan to a corresponding value;
if E1 is more than E and less than or equal to E2, the central control processor uses gamma 2 to regulate the rotating speed of the fan;
if E > E2, the central control processor uses gamma 3 to adjust the rotating speed of the fan to a corresponding value;
the central control processor marks the rotating speed of the fan regulated by gamma k as V ', and sets V' =V0×gamma k, wherein k=1, 2,3 and V0 are the initial rotating speeds of the fan.
8. The reduced loss frequency converter protection system of claim 7, wherein the central control processor controls the temperature detector to detect the temperature T of the IGBT when it is determined that the IGBT is at risk of loss increase, corrects the rotational speed of the fan according to the detected result, and is provided with a first preset standard temperature T1, a second preset standard temperature T2, a first rotational speed correction coefficient ε 1, and a second rotational speed correction coefficient ε 2, wherein T1 < T2,1.2 < ε 1 < ε 2 < 1.7,
if T is less than or equal to T1, the central control processor judges that the rotating speed of the fan accords with a preset standard cone;
if T1 is more than T and less than or equal to T2, the central control processor corrects the rotating speed of the fan by using epsilon 1;
if T is more than T2, the central control processor corrects the rotating speed of the fan by using epsilon 2;
the central control processor marks the rotation speed of the fan regulated by epsilon e as V ', wherein e=1, 2, and V ' =V ' ×epsilon e is set.
9. The system of claim 8, wherein the central processor calculates the operating power Pm of the fan by comparing the temperature T of the IGBT with each preset standard temperature and correcting the rotational speed of the fan according to the comparison result, compares the operating power Pm of the fan with the preset operating power Ph set for the fan in the central processor, determines whether to reduce the rotational speed of the fan according to the comparison result,
if Pm is less than or equal to Ph, the central control processor judges that the running power of the fan meets the standard;
if Pm > Ph, the central control processor judges to reduce the rotating speed of the fan so as to enable the operating power of the fan to meet the standard.
10. A frequency converter based on the protection system of any one of claims 1-9, comprising:
a main body in which a counter and a temperature detector are provided for adjusting the voltage and frequency of the output power supplied to the load; the counter is used for recording the switching times of the IGBT; the temperature detector is used for detecting the temperature of the IGBT;
the heat dissipation device is connected with the frequency converter and used for adjusting the temperature of the environment where the frequency converter is located, and the heat dissipation device comprises a fan and is used for adjusting the temperature of the environment where the frequency converter is located to a corresponding value by using a preset rotating speed.
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| CN116488330B (en) * | 2023-04-12 | 2023-10-10 | 国网黑龙江省电力有限公司齐齐哈尔供电公司 | Informationized remote control system based on big data |
| CN116191856B (en) * | 2023-04-27 | 2023-08-01 | 张家港市升恒机械设备制造有限公司 | Mining wisdom frequency conversion actuating system |
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