CN115694136A - 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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- CN115694136A CN115694136A CN202211455113.1A CN202211455113A CN115694136A CN 115694136 A CN115694136 A CN 115694136A CN 202211455113 A CN202211455113 A CN 202211455113A CN 115694136 A CN115694136 A CN 115694136A
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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 and a frequency converter with reduced loss, 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 is used for adjusting the voltage and the frequency transmitted to the load by the output power supply according to the running power of the load; 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 to a corresponding value by using a preset rotating speed; the output power supply is connected with the frequency converter and is used for transmitting voltage and frequency with corresponding values to the frequency converter; and the central control processor is used for controlling the frequency converter to regulate the voltage and the frequency transmitted to the load by the output power supply to corresponding values according to the running power of the load. According to the invention, the rotation speed of the fan is adjusted through 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 an electric control device which applies a frequency conversion technology and a microelectronic technology and controls an alternating current motor by changing the frequency mode of a working power supply of the motor. The frequency converter can realize multiple control means such as soft start, multi-stage speed, low-speed high-efficient operation of electrical equipment, and the parameter of accessible adjustment frequency converter can reach different demand effects under the operating mode condition of difference.
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, and then the motor is controlled, however, in the process of conducting and running the control circuit board from starting, the electric energy in the control circuit board can be partially dissipated through the forms 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 includes 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 heat dissipation fan through a wire, the heat dissipation fan is located above a heat dissipation fin, the heat dissipation fin is arranged on the upper side of the frequency converter control circuit board, and the heat dissipation fin is provided with a heat conduction assembly.
The prior art can not cause the frequency converter loss increase caused by excessive IGBT switching times according to the large change amplitude of the voltage output to the load by the frequency converter.
Disclosure of Invention
In order to achieve the purpose, the invention provides a frequency converter protection system with reduced loss and a frequency converter to solve the problem that in the prior art, the frequency converter is low in protection efficiency due to the fact that the frequency of switching of an IGBT is too high and loss of the frequency converter is increased.
In one aspect, the present invention provides a frequency converter protection system with reduced loss, including:
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 is used for adjusting the voltage and the frequency transmitted to the load by the output power supply 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 located, and the heat dissipation device comprises a fan which 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;
the output power supply is connected with the frequency converter and is used for transmitting voltage and frequency with corresponding values to the frequency converter;
and 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 regulate the voltage and the frequency which are transmitted to the load by the output power supply to corresponding values according to the running power of the load, judging whether the IGBT has loss increasing risks according to the voltage and the frequency regulated by the frequency converter, and regulating the rotating speed of the fan to the 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 the IGBT is judged to have the loss increasing risks.
Further, the central control processor controls the power detector to detect the operating power P of the load so as to judge whether the voltage and the frequency transmitted to the load by the frequency converter are adjusted to corresponding values according to P, the central control processor is provided with a preset power P0,
if P is less than P0, the central control processor judges that the actual operating power of the load does not accord with a preset standard, calculates the difference value delta P between P0 and P, adjusts the voltage output to the load by the frequency converter to a corresponding value according to delta P, and sets delta P = P0-P;
if P = P0, the central control processor judges that the actual operating power of the load meets a preset standard;
if P is larger than P0, the central control processor judges that the actual operating power of the load does not meet a preset standard, the IGBT has a 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 adjusted to a corresponding value or not.
Further, the central control processor adjusts the voltage output by the frequency converter to the load to a corresponding value according to the difference value delta P between the preset power P0 and the running power P of the load under a first preset condition, a first preset power difference value delta P1, a second preset power difference value delta P2, a first preset voltage adjusting coefficient alpha 1 and a second preset voltage adjusting coefficient alpha 2 are arranged in the central control processor, wherein the delta P1 is less than the delta P2,1 is less than the alpha 1 and less than the alpha 2 and less than 1.4,
if the delta P is less than or equal to the delta P1, the central control processor judges that the actual operation power of the load meets a preset standard;
if delta P1 is less than delta P and less than or equal to delta P2, the central control processor judges that the actual operating power of the load does not meet a preset standard, and the central control processor adjusts the voltage output to the load by the frequency converter by using alpha 1;
if delta P is > -delta P2, the central control processor judges that the actual operating power of the load does not meet a preset standard, and the central control processor adjusts the voltage output to the load by the frequency converter by using alpha 2;
the central control processor records the voltage output to the load by the frequency converter after being regulated by the alpha i as U ', and sets U' = U0 multiplied by the 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 judges that the actual running power P of the load is smaller than a preset power P0.
Further, the central control processor repeatedly adjusts the operating power of the load, records the actual operating power of the adjusted load as P ', adjusts the frequency output by the frequency converter to the load to a corresponding value by selecting a corresponding frequency according to the difference delta Pa between P0 and P' if the adjusted voltage U 'is greater than a first preset critical voltage Uamax set in the central control processor and P' < P0, and is provided with a first frequency adjusting coefficient beta 1, a second frequency adjusting coefficient beta 2 and a third frequency adjusting coefficient beta 3, wherein beta 1 is greater than beta 1 and less than beta 2 and less than beta 3 and less than 1.5,
if the delta Pa is less than or equal to the delta P1, the central control processor adjusts the frequency output to the load by the frequency converter to a corresponding value by using the beta 1;
if delta P1 is less than delta Pa and less than or equal to delta P2, the central control processor adjusts the frequency output by the frequency converter to the load to a corresponding value by using beta 2;
if Δ Pa > - Δ P2, the central processor adjusts the frequency output by the frequency converter to the load to a corresponding value using β 3;
the central control processor records the frequency output to the load by the frequency converter after being adjusted by using the β j as f ', wherein f' = f0 × β j, and j =1,2,3, and f0 is set as the initial frequency output to the load by the frequency converter.
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 loss increasing 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;
the second preset condition is that the central control processor determines 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 IGBT operating parameters under a third preset condition to calculate a risk assessment value E of the IGBT, wherein the operating parameters comprise the switching times M, the voltage Ug and the frequency f of the IGBT in a single period t, and the setting is carried out
Where a is a first weight coefficient, and a =0.4V is set -1 And b is a second weight coefficient,set b =0.3Hz -1 C is a third weight coefficient, and c =0.3s is set -1 ；
The third preset condition is that the central control processor determines that the regulated voltage U 'output to the load by the frequency converter meets U' > Ubmax > Uamax.
Further, the central control processor adjusts the rotation 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 standard E1, a second preset risk assessment standard E2, a first rotation speed adjustment coefficient gamma 1, a second rotation speed adjustment coefficient gamma 2 and a third rotation 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 adjusts the rotating speed of the fan to a corresponding value by using gamma 1;
if E1 is larger than E and is smaller than or equal to E2, the central control processor adjusts the rotating speed of the fan by using gamma 2;
if E is larger than E2, the central control processor adjusts the rotating speed of the fan to a corresponding value by using gamma 3;
the central processor records the rotation speed of the fan adjusted by using γ k as V ', and sets V' = V0 × γ k, where k =1,2,3 and V0 is the initial rotation speed 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 loss increasing risk, corrects the rotating speed of the fan according to the detection result, 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 T2,1.2 is less than epsilon 1 and less than epsilon 2 and 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 vertebra;
if T1 is larger than T and is not larger than T2, the central control processor corrects the rotating speed of the fan by using epsilon 1;
if T is larger than T2, the central control processor corrects the rotating speed of the fan by using epsilon 2;
the central processor records the rotation speed of the fan adjusted using ∈ e as V ″, where e =1,2 and V = V' × ∈ e is set.
Further, the central control processor compares the temperature T of the IGBT with each preset standard temperature, corrects the rotating speed of the fan according to the comparison result, calculates the operating power Pm of the fan, compares the operating power Pm of the fan with the preset operating power Ph set for the fan in the central control processor, judges whether to reduce the rotating 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 operating power of the fan meets the standard;
if Pm is greater than Ph, the central control processor determines 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 further provides a frequency converter based on the protection system of any one of claims 1 to 9, including:
a main body in which a counter and a temperature detector are provided to adjust the voltage and frequency delivered from an output power source to a 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;
and 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 which 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 invention has the advantages that the voltage and the frequency transmitted to the load by the frequency converter are adjusted to corresponding values by detecting the operating power of the load, and the voltage and the frequency flowing through the load are adjusted, so that the load can be prevented from overvoltage and overcurrent, and the loss of the frequency converter is effectively reduced; according to the invention, the rotation speed of the fan is adjusted by counting the switching times of the IGBT in a single preset period and detecting the temperature of the environment where the IGBT is located, and the loss of the IGBT can be effectively reduced by adjusting the rotation speed of the fan when the IGBT is switched too many times and the temperature is too high, so that the protection efficiency of the protection system for the frequency converter is effectively improved.
Furthermore, the invention judges whether the running power of the load meets the standard or not by comparing the running power P of the load with the preset power, and adjusts the condition that the load power does not meet the standard in time by detecting the running power of the load, thereby avoiding the damage of parts in the frequency converter caused by the failure of a circuit due to the untimely detection and indirectly protecting the frequency converter.
Furthermore, the central control processor is provided with a plurality of preset power difference values and a plurality of voltage regulating coefficients, the voltage transmitted to the load by the frequency converter is regulated to a corresponding value according to the comparison result by comparing the delta P with each preset power difference value, and the voltage flowing 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 overvoltage, the frequency converter is protected, and the protection efficiency of the protection system for the frequency converter is further improved.
Furthermore, the central control processor is provided with a first preset critical voltage Uamax, when the central control processor can not adjust the operating power of the load to a corresponding value after repeatedly adjusting the operating power of the load, the first preset critical voltage is compared with each preset power difference value, the frequency output by the frequency converter to the load is adjusted according to the comparison result so that the operating power of the load is adjusted to the corresponding value, the operating power of the load is enabled to meet the standard by adjusting the frequency, the load is enabled to normally operate, the frequency converter is protected, and the protection efficiency of the protection system for the frequency converter is further improved.
Furthermore, the central control processor is provided with a second preset critical voltage Ubmax, the repeatedly adjusted voltage is compared with the second preset critical voltage, whether the IGBT has loss increasing risks is judged according to the comparison result, the state of the IGBT of the frequency converter is evaluated, the IGBT is prevented from being damaged due to overlarge voltage caused by untimely judgment, and the protection efficiency of the protection system is effectively improved.
Furthermore, the central control processor is provided with a plurality of preset risk evaluation standards and a plurality of rotating speed adjusting coefficients, the rotating speed of the fan is adjusted by comparing the risk evaluation value of the IGBT with each preset risk evaluation standard, the temperature of the IGBT is reduced by increasing the rotating 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.
Furthermore, the central control processor is provided with a 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, and if the corrected operating power is greater than the preset operating power, the rotating speed of the fan is reduced to protect the fan, so that reasonable operation of the device in the protection system is effectively ensured, the device is prevented from being damaged, 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 with reduced loss according to an embodiment of the present invention;
fig. 2 is a flowchart illustrating the voltage outputted from the frequency converter to the load being adjusted to a corresponding value according to the power difference Δ P according to the embodiment of the present invention;
fig. 3 is a flowchart illustrating adjusting the frequency output by the frequency converter to the load to a corresponding value according to the power difference Δ Pa according to the embodiment of the present invention;
fig. 4 is a flowchart illustrating the fan speed adjustment 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 be more clearly understood, the invention is further described below with reference to examples; it should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit 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 only for explaining the technical principle of the present invention, and do not limit the scope of the present invention.
It should be noted that in the description of the present invention, the terms of direction or positional relationship indicated by the terms "upper", "lower", "left", "right", "inner", "outer", etc. are based on the directions or positional relationships shown in the drawings, which are only for convenience of description, and do not indicate or imply that the device or element must have a specific orientation, be constructed in a specific orientation, and be operated, 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 otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
Fig. 1 is a schematic structural diagram of a frequency converter protection system with reduced loss according to an embodiment of the present invention, where the frequency converter protection system with reduced loss includes:
a load (not shown) externally connected with a power detector (not shown) for detecting the operation power of the load;
the frequency converter is connected with the load and is used for adjusting the voltage and the frequency transmitted to the load by the output power supply according to the running power of the load; the frequency converter is provided with 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;
the heat dissipation device (not shown in the figure) is connected with the frequency converter and is used for adjusting the temperature of the environment where the frequency converter is located, and the heat dissipation device comprises a fan which 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;
the output power supply is connected with the frequency converter and is used for transmitting 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 regulate the voltage and the frequency which are transmitted to the load by the output power supply to corresponding values according to the running power of the load, judging whether the IGBT has loss increasing risks according to the regulated voltage and frequency of the frequency converter, and regulating 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 the IGBT is judged to have the loss increasing risks.
Specifically, the central control processor controls the power detector to detect the running power P of the load so as to determine whether the voltage and the frequency transmitted by the frequency converter to the load are adjusted to corresponding values according to P, a preset power P0 is set in the central control processor,
if P is less than P0, the central control processor judges that the actual operating power of the load does not accord with a preset standard, the central control processor calculates the difference value delta P between P0 and P, adjusts the voltage output to the load by the frequency converter to a corresponding value according to delta P, and sets delta P = P0-P;
if P = P0, the central control processor judges that the actual operating power of the load meets a preset standard;
if P is larger than P0, the central control processor judges that the actual operating power of the load does not meet a preset standard, the IGBT has a loss increasing risk, 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 adjusted to a corresponding value or not.
The invention judges whether the running power of the load meets the standard or not by comparing the running power P of the load with the preset power, and adjusts the condition that the load power does not meet the standard in time by detecting the running 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 protecting the frequency converter.
Please refer to fig. 2, which is a flowchart illustrating an embodiment of adjusting a voltage outputted from a frequency converter to a load to a corresponding value according to a power difference Δ P, wherein the central processor adjusts the voltage outputted from the frequency converter to the load to the corresponding value according to a difference Δ P between the preset power P0 and an operating power P of the load under a first preset condition, the central processor is provided with a first preset power difference Δ P1, a second preset power difference Δ P2, a first preset voltage adjustment coefficient α 1, and a second preset voltage adjustment coefficient α 2, where Δ P1 is smaller than Δ P2,1 < α 2 < 1.4,
if the delta P is less than or equal to the delta P1, the central control processor judges that the actual operating power of the load meets a preset standard;
if delta P1 is less than delta P and less than or equal to delta P2, the central control processor judges that the actual operating power of the load does not meet a preset standard, and the central control processor adjusts the voltage output to the load by the frequency converter by using alpha 1;
if delta P is > -delta P2, the central control processor judges that the actual operating power of the load does not meet a preset standard, and the central control processor adjusts the voltage output to the load by the frequency converter by using alpha 2;
the central control processor records the voltage output to the load by the frequency converter after being regulated by the α i as U ', and sets U' = U0 × α 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 judges that the actual running power P of the load is smaller than a preset power P0.
The central control processor is provided with a plurality of preset power difference values and a plurality of voltage adjusting coefficients, the voltage transmitted to the load by the frequency converter is adjusted to a corresponding value according to the comparison result by comparing the delta P with each preset power difference value, and the voltage flowing through the load is adjusted to ensure that the whole circuit is smooth, so that the frequency converter is prevented from being damaged due to overvoltage, the effect of protecting the frequency converter is achieved, and the protection efficiency of the protection system for the frequency converter is further improved.
Referring to fig. 3, which is a flowchart illustrating an embodiment of the present invention for adjusting the frequency output from the frequency converter to the load to a corresponding value according to a power difference Δ Pa, the central processing unit 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 the first predetermined threshold voltage Uamax set in the central processing unit and P '< P0, the central processing unit adjusts the frequency output from the frequency converter to the load to a corresponding value by selecting a corresponding frequency according to the difference Δ Pa between P0 and P', and is provided with a first frequency adjustment coefficient β 1, a second frequency adjustment coefficient β 2, and a third frequency adjustment coefficient β 3, where β 1 < β 2 < β 3 < 1.5,
if delta Pa is less than or equal to delta P1, the central control processor adjusts the frequency output by the frequency converter to the load to a corresponding value by using beta 1;
if delta P1 is less than delta Pa and less than or equal to delta P2, the central control processor adjusts the frequency output by the frequency converter to the load to a corresponding value by using beta 2;
if Δ Pa > - Δ P2, the central processor adjusts the frequency output by the frequency converter to the load to a corresponding value using β 3;
the central control processor records the frequency output to the load by the frequency converter after being adjusted by using the beta j as f ', wherein f' = f0 multiplied by the beta j, j =1,2,3, f0 is set as the initial frequency output to the load by the frequency converter.
The central control processor is provided with a first preset critical voltage Uamax, when the central control processor can not adjust the operating power of the load to a corresponding value after repeatedly adjusting the operating power of the load, the first preset critical voltage is compared with each preset power difference value, the frequency output by the frequency converter to the load is adjusted according to the comparison result so that the operating power of the load is adjusted to the corresponding value, and the operating power of the load is enabled to meet the standard by adjusting the frequency so that the load normally operates, 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;
the second preset condition is that the central control processor determines that the regulated voltage U 'output to the load by the frequency converter meets U' > Uamax.
According to the invention, 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 increasing 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 IGBT is prevented from being damaged due to overlarge voltage caused by untimely judgment, 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 IGBT operating parameters under a third preset condition to calculate a risk assessment value E of the IGBT, wherein the operating parameters comprise 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 the setting is carried out
Where a is a first weight coefficient, and a =0.4V is set -1 B is a second weight coefficient, and b =0.3Hz -1 C is a third weight coefficient, and c =0.3s is set -1 ；
The third preset condition is that the central control processor determines 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 assessment value E of the IGBT under the third preset condition, the central control processor is provided with a first preset risk assessment standard E1, a second preset risk assessment standard E2, a first rotating speed adjusting coefficient gamma 1, a second rotating speed adjusting coefficient gamma 2 and a third rotating speed adjusting 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 adjusts the rotating speed of the fan to a corresponding value by using gamma 1;
if E1 is larger than E and is smaller than or equal to E2, the central control processor adjusts the rotating speed of the fan by using gamma 2;
if E is larger than E2, the central control processor adjusts the rotating speed of the fan to a corresponding value by using gamma 3;
the central control processor records the rotation speed of the fan adjusted by using γ k as V ', and sets V' = V0 × γ k, where k =1,2,3 and V0 is the initial rotation speed of the fan.
The central control processor is provided with a plurality of preset risk evaluation standards and a plurality of rotating speed adjusting coefficients, the rotating speed of the fan is adjusted by comparing the risk evaluation value of the IGBT with each preset risk evaluation standard, the loss of the IGBT is reduced by increasing the rotating speed of the fan and reducing the temperature of the IGBT, and the protection efficiency of the protection system for the frequency converter is effectively improved.
Referring to fig. 4, which is a flowchart illustrating the fan speed is adjusted to a corresponding value according to the risk assessment value of the IGBT according to the embodiment of the present invention, when it is determined that the IGBT has a risk of loss increase, the central processor controls the temperature detector to detect the temperature T of the IGBT, and corrects the fan speed according to the detection result, the central processor is provided with a first preset standard temperature T1, a second preset standard temperature T2, a first speed correction coefficient ∈ 1, and a second speed correction coefficient ∈ 2, where T1 < T2,1.2 < ∈ 1 < ∈ 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 vertebra;
if T1 is larger than T and smaller than or equal to T2, the central control processor corrects the rotating speed of the fan by using epsilon 1;
if T is larger than T2, the central control processor corrects the rotating speed of the fan by using epsilon 2;
the central processor records the rotation speed of the fan adjusted using ∈ e as V ″, where e =1,2 and V = V' × ∈ e is set.
Specifically, the central control processor compares the temperature T of the IGBT with each preset standard temperature, then corrects the rotating speed of the fan according to the comparison result, calculates the operating power Pm of the fan, compares the operating power Pm of the fan with the preset operating power Ph set for the fan in the central control processor, and judges whether to reduce the rotating 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 operating power of the fan meets the standard;
if Pm is greater than Ph, the central control processor determines 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 a 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, and if the corrected operating power is greater than the preset operating power, the rotating speed of the fan is reduced to protect the fan, so that the reasonable operation of the device in the protection system is effectively ensured, the device is prevented from being damaged, and the protection efficiency of the protection system for the frequency converter is further improved.
In another aspect, the present invention further provides a frequency converter based on the protection system of any one of claims 1 to 9, including:
a main body in which a counter and a temperature detector are provided to adjust the voltage and frequency delivered from an output power source to a 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;
and 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 which 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.
So far, the technical solutions of the present invention have 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 the present invention is obviously not limited to these specific embodiments. Equivalent changes or substitutions of related technical features can be made by those skilled in the art without departing from the principle of the invention, and the technical scheme after the changes or substitutions can be within the protection scope of the invention.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention; various modifications and alterations to this invention will become apparent to those skilled in the art. Any modification, equivalent replacement, or improvement 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 reduced-loss 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 is used for adjusting the voltage and the frequency transmitted to the load by the output power supply 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 located, and the heat dissipation device comprises a fan which 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;
the output power supply is connected with the frequency converter and is used for transmitting voltage and frequency with corresponding values to the frequency converter;
and 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 regulate the voltage and the frequency which are transmitted to the load by the output power supply to the corresponding values according to the running power of the load, judging whether the IGBT has loss increasing risks according to the regulated voltage and frequency of the frequency converter, and regulating the rotating speed of the fan to the 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 the IGBT is judged to have the loss increasing risks.
2. The reduced-loss inverter protection 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 delivered to the load by the inverter to corresponding values according to P, wherein the central processor has a predetermined power P0,
if P is less than P0, the central control processor judges that the actual operating power of the load does not accord with a preset standard, calculates the difference value delta P between P0 and P, adjusts the voltage output to the load by the frequency converter to a corresponding value according to delta P, and sets delta P = P0-P;
if P = P0, the central control processor judges that the actual operating power of the load meets a preset standard;
if P is larger than P0, the central control processor judges that the actual operating power of the load does not meet a preset standard, the IGBT has a loss increasing risk, 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 adjusted to a corresponding value or not.
3. The reduced-loss protection system for frequency converters of claim 2, wherein the central processor adjusts the voltage outputted from the frequency converter to the load to a corresponding value according to the difference Δ P between the preset power P0 and the operating power P of the load under a first preset condition, and the central processor is provided with a first preset power difference Δ P1, a second preset power difference Δ P2, a first preset voltage adjustment coefficient α 1 and a second preset voltage adjustment coefficient α 2, wherein Δ P1 is less than Δ P2,1 < α 2 < 1.4,
if the delta P is less than or equal to the delta P1, the central control processor judges that the actual operation power of the load meets a preset standard;
if delta P1 is less than delta P and less than or equal to delta P2, the central control processor judges that the actual operating power of the load does not meet a preset standard, and the central control processor adjusts the voltage output to the load by the frequency converter by using alpha 1;
if delta P is > -delta P2, the central control processor judges that the actual operating power of the load does not meet a preset standard, and the central control processor adjusts the voltage output to the load by the frequency converter by using alpha 2;
the central control processor records the voltage output to the load by the frequency converter after being regulated by the α i as U ', and sets U' = U0 × α 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 judges that the actual running power P of the load is smaller than a preset power P0.
4. The frequency converter protection system with reduced loss as claimed in claim 3, wherein the central 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 set in the central processor and P '< P0, the central processor selects a corresponding frequency according to a difference Δ Pa between P0 and P' to adjust the frequency output by the frequency converter to the load to a corresponding value, the central processor is provided with a first frequency adjustment coefficient β 1, a second frequency adjustment coefficient β 2 and a third frequency adjustment coefficient β 3, wherein 1.1 < β 1 < β 2 < β 3 < 1.5,
if the delta Pa is less than or equal to the delta P1, the central control processor adjusts the frequency output to the load by the frequency converter to a corresponding value by using the beta 1;
if delta P1 is less than delta Pa and less than or equal to delta P2, the central control processor adjusts the frequency output by the frequency converter to the load to a corresponding value by using beta 2;
if Δ Pa > - Δ P2, the central processor adjusts the frequency output by the frequency converter to the load to a corresponding value using β 3;
the central control processor records the frequency output to the load by the frequency converter after being adjusted by using the beta j as f ', wherein f' = f0 multiplied by the beta j, j =1,2,3, f0 is set as the initial frequency output to the load by the frequency converter.
5. The reduced-loss frequency converter protection system of claim 4, wherein the central processor compares U' with a second preset critical voltage Ubmax set in the central processor under a second preset condition, and determines whether the IGBT has a loss increase risk according to the comparison result, ubmax > Uamax is set,
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;
the second preset condition is that the central control processor determines that the regulated voltage U 'output to the load by the frequency converter meets U' > Uamax.
6. The reduced-loss frequency converter protection system as claimed in claim 5, wherein the central processor obtains historical data of IGBT operating parameters under a third preset condition to calculate an IGBT risk evaluation value E, the operating parameters including the number of switching times M in a single period t, the voltage Ug flowing through the IGBT and the frequency f flowing through the IGBT, sets a switching frequency M, and sets a switching frequency M in a single period t
Where a is a first weight coefficient, and a =0.4V is set -1 B is a second weight coefficient, and b =0.3Hz -1 C is a third weight coefficient, and c =0.3s is set -1 ；
The third preset condition is that the central control processor determines 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 as claimed in claim 6, wherein said central processor adjusts the rotation speed of said fan to a corresponding value according to the risk assessment value E of said IGBT under said third preset condition, and is provided with a first preset risk assessment criterion E1, a second preset risk assessment criterion E2, a first rotation speed adjustment coefficient γ 1, a second rotation speed adjustment coefficient γ 2, and a third rotation speed adjustment coefficient γ 3, wherein E1 < E2,1 < γ 2 < γ 3 < 1.6,
if E is less than or equal to E1, the central control processor adjusts the rotating speed of the fan to a corresponding value by using gamma 1;
if E1 is larger than E and is not larger than E2, the central control processor adjusts the rotating speed of the fan by using gamma 2;
if E is larger than E2, the central control processor adjusts the rotating speed of the fan to a corresponding value by using gamma 3;
the central processor records the rotation speed of the fan adjusted by using γ k as V ', and sets V' = V0 × γ k, where k =1,2,3 and V0 is the initial rotation speed of the fan.
8. The reduced-loss frequency converter protection system according to claim 7, wherein said central processor controls said temperature detector to detect the temperature T of said IGBT when determining that there is a risk of loss increase in said IGBT, and corrects the rotation speed of said fan according to the detection result, wherein said central processor is provided with a first preset standard temperature T1, a second preset standard temperature T2, a first rotation speed correction coefficient ε 1 and a second rotation 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 vertebra;
if T1 is larger than T and smaller than or equal to T2, the central control processor corrects the rotating speed of the fan by using epsilon 1;
if T is larger than T2, the central control processor corrects the rotating speed of the fan by using epsilon 2;
the central processor records the rotation speed of the fan adjusted using ∈ e as V ″, where e =1,2 and V = V' × ∈ e is set.
9. The loss-reducing frequency converter protection system according to claim 8, wherein the central processor compares the temperature T of the IGBT with each preset standard temperature, then corrects the rotation speed of the fan according to the comparison result, then calculates the operating power Pm of the fan, compares the operating power Pm of the fan with a preset operating power Ph set for the fan in the central processor, and determines whether to reduce the rotation 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 operating power of the fan meets the standard;
if Pm is greater than Ph, the central control processor determines 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 a protection system according to any one of claims 1 to 9, comprising:
a main body in which a counter and a temperature detector are provided to adjust the voltage and frequency delivered from an output power source to a 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;
and 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 which 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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