CN103078482B - Overcurrent detecting circuit and frequency converter device with same - Google Patents
Overcurrent detecting circuit and frequency converter device with same Download PDFInfo
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Abstract
The invention relates to an overcurrent detecting circuit and a frequency converter device with the same. The overcurrent detecting circuit is characterized by comprising a voltage input part, a rectifying part, an inverse transformation part, a voltage value selection part, an overcurrent suppression judgment part and an overcurrent lockout judgment part, wherein the voltage input part is used for inputting input voltage obtained by converting detected output current of the frequency converter device; the rectifying part is provided with a diode array forming a full-wave rectification circuit and is used for rectifying the input voltage received from the voltage input part; the inverse transformation part is used for inversely transforming a voltage waveform received from a common positive end of the rectifying part; the voltage value selection part is used for selectively enabling the voltage waveform with a small voltage value to pass through in the voltage waveform output by a common negative end of the rectifying part and the voltage waveform output by the inverse transformation part; the overcurrent suppression judgment part is used for judging whether an overcurrent suppression function is activated or not according to the voltage value received from the voltage value selection part; and the overcurrent lockout judgment part is used for judging whether an overcurrent lockout function is activated or not according to the voltage value received from the voltage value selection part.
Description
Technical field
The present invention relates to a kind of frequency-converter device, especially relate to a kind of overcurrent sensing circuit of frequency-converter device.
Background technology
Usually, frequency-converter device is a kind of by regulating the device regulating the speed of motor from the frequency of the electric power of electrical network input.Utilize the motor speed adjusting of frequency-converter device, have speed-regulating range width, adjusting speed accuracy is high, and dynamic response is fast, and low speed torque is good, energy savings, the advantages such as operating efficiency is high, easy to use.
Utilize frequency-converter device to carry out speed governing, motor can not only be made to run under energy-conservation rotating speed, but also the control precision of motor speed can be increased substantially, thus people can improve processing quality and production efficiency.
The load mainly motor of frequency-converter device.Once the excessive even stall of motor load, if frequency-converter device does not take safeguard measure, frequency-converter device can be caused overheated and break down.Therefore, existing frequency-converter device has overcurrent sensing circuit, to take safeguard measure when there is such situation.
Fig. 1 shows the figure of the overcurrent sensing circuit of existing frequency-converter device.
As shown in Figure 1, the overcurrent sensing circuit of existing frequency-converter device comprises: voltage input part 1, it is for inputting three-phase input voltage, and output current change of this three-phase input voltage to the frequency-converter device utilizing current sensor etc. to detect obtains; Rectification part 2, it has the diode array forming three-phase full wave rectifier circuit, for carrying out rectification to the three-phase input voltage received from voltage input part 1; OCS judging part 3, according to the voltage received from common anode end Tanode and the common cathode end Tcathode of the diode array of rectification part 2, it judges whether that starting overcurrent suppresses (OCS, Over Current Suppression) function; OCT judging part 4, according to the voltage received from common anode end Tanode and the common cathode end Tcathode of the diode array of rectification part 2, it judges whether that starting overcurrent blocks (OCT, Over Current Trip) function.
Fig. 2 is the oscillogram of the alternating voltage of each phase of the three-phase input voltage inputted from the voltage input part 1 of the overcurrent sensing circuit of existing frequency-converter device.
As shown in Figure 2, the waveform of alternating voltage Vu, Vv, Vw of each phase of the three-phase input voltage inputted from the voltage input part 1 of the overcurrent sensing circuit of existing frequency-converter device be cycle and amplitude identical and each mutually between phase difference be the sine wave of 120 degree, the number range of the magnitude of voltage of each phase all at 0 ~+Vcc, the voltage waveform of each phase with Vcc/2 axle for reference symmetry.Above-mentioned " voltage waveform with Vcc/2 axle for reference symmetry " refers to, voltage waveform with by this voltage waveform along ω t axle+voltage waveform that direction or-direction are moved the half period and obtained with Vcc/2 axle for benchmark is symmetrical up and down.
Though alternating voltage Vu, Vv, Vw of figure 2 illustrates each phase of three-phase input voltage are the situation of desirable sine wave, the actual waveform of alternating voltage Vu, Vv, Vw of each phase is the sine wave comprising high-frequency harmonic composition.Now, the actual waveform of alternating voltage Vu, Vv, Vw of each phase is also considered as belonging to the situation of " voltage waveform with Vcc/2 axle for reference symmetry ".
As shown in Figure 2, the sine wave of the alternating voltage of arbitrary phase of three-phase input voltage, the position becoming Vcross or V ' cross at the magnitude of voltage of this phase intersects with the voltage waveform of another adjacent phase.In other words, alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage become Vcross each crossover node a, b, c, d with its magnitude of voltage alternately have maximum voltage value for benchmark, and become each crossover node a ' of V ' cross, b ', c ', d ' with its magnitude of voltage and alternately have minimum amount of voltage that for benchmark.When actual waveform contains high-frequency harmonic composition, compared with the situation of desirable sine wave, except the position of each crossover node changes near Vcross or near V ' cross, alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage also with each crossover node near Vcross for benchmark alternately has maximum voltage value, and be that benchmark alternately has minimum amount of voltage that with each crossover node near V ' cross.
Due to the voltage waveform of each phase with Vcc/2 axle for reference symmetry, so set up formula (1).
V’cross=Vcc-Vcross（Vcc＞Vcross＞V’cross＞0） （1）
Rectification part 2 utilizes 6 diodes to form three-phase full wave rectifier circuit.With regard to three the top diodes be connected with the common cathode end Tcathode of rectification part 2, only make the diode current flow be connected with the alternating voltage that in alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage, there is the phase of maximum voltage value, now, suppose that the forward voltage drop tube of each diode of rectification part 2 is V
f1, so, the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 can be calculated by following formula (2).
Vcathode=Vmax-V
F1 （2）
Wherein, Vmax refers to, in arbitrary enough little time interval (or between phase region), has the waveform of the alternating voltage of the phase of maximum voltage value in alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage.Wherein, so-called time interval (or between phase region) " enough little " refers to, in this time interval (or between phase region), the alternating voltage that there is the phase of more than 2 time different has maximum voltage value, or the alternating voltage of the phase asynchronously having more than 2 has minimum amount of voltage that.
Also have, with regard to 3 the bottom diodes be connected with the common anode end Tanode of rectification part 2, as shown in Figure 1, because the common anode end Tanode in rectification part 2 is applied with high voltage Vcc, thus the diode current flow be connected with the alternating voltage that in alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage, there is the phase of minimum amount of voltage that is only made, now, the magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2 can be calculated by following formula (3).
Vanode=Vmin+V
F1 （3）
Wherein, Vmin refers to, in arbitrary enough little time interval (or between phase region), has the waveform of the alternating voltage of the phase of minimum amount of voltage that in alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage.
As mentioned above, the waveform of alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage be cycle and amplitude identical and each mutually between phase difference be the sine wave of 120 degree, the voltage waveform of each phase with Vcc/2 axle for reference symmetry, and consider above formula (1), then can set up following formula (4).
Vmin=Vcc-Vmax （4）
Fig. 3 is the oscillogram of the three-phase input voltage of the action of overcurrent sensing circuit for illustration of existing frequency-converter device.With regard to the overcurrent sensing circuit of existing frequency-converter device, the phase difference between alternating voltage Vu, Vv, Vw due to each phase of three-phase input voltage is 120 degree, alternating voltage Vu, Vv, Vw of each phase respective sinusoidal wave period and amplitude identical, even so the alternating voltage of arbitrary phase in alternating voltage Vu, Vv, Vw of each phase (such as, U phase voltage Vu) also can represent the alternating voltage of other phases (such as, V phase voltage Vv or W phase voltage Vw) behavior, thus illustrate only the waveform of the U phase voltage Vu in Fig. 2 in figure 3.Below, utilize the waveform of U phase voltage Vu so that the action of overcurrent sensing circuit to be described.Wherein, the waveform of voltage Vu is not desirable sine wave, but comprises the practical sinusoidal wave (the heavy line part in Fig. 3) of high-frequency harmonic composition.
With reference to Fig. 3, in the waveform of U phase voltage Vu, magnitude of voltage is the part (being positioned at the bold portion of the top of Vcc/2 axle) of more than Vcross is exactly above-mentioned voltage waveform Vmax, magnitude of voltage is the part (being positioned at the bold portion of the below of Vcc/2 axle) of V ' below cross is exactly above-mentioned voltage waveform Vmin, and voltage waveform Vmax and Vmin of these 2 parts can have influence on the magnitude of voltage Vcathode of the common cathode end Tcathode of the rectification part 2 and magnitude of voltage Vanode of common anode end Tanode.
OCS judging part 3 comprises: the first comparator 31, it is made up of operational amplifier, receive the magnitude of voltage Vcathode that exports from the common cathode end Tcathode of rectification part 2 and compare with the OCS reference voltage value Vref1 preset, judging whether thus to start overcurrent suppression (OCS) function; Second comparator 32, it is made up of operational amplifier, receive the magnitude of voltage Vanode that exports from the common anode end Tanode of rectification part 2 and compare with the 2nd OCS reference voltage value V ' ref1 preset, judging whether thus to start overcurrent suppression (OCS) function.Now, in the first comparator 31, whether the magnitude of voltage Vcathode that multilevel iudge exports from the common cathode end Tcathode of rectification part 2 is OCS more than the reference voltage value Vref1 preset, that is, whether the magnitude of voltage of voltage waveform Vmax that multilevel iudge inputs to rectification part 2 is Vref1+V
f1above, and in the second comparator 32, whether the magnitude of voltage Vanode that multilevel iudge exports from the common anode end Tanode of rectification part 2 is the 2nd OCS reference voltage value V ' below the ref1 preset, that is, whether the magnitude of voltage of voltage waveform Vmin that multilevel iudge inputs to rectification part 2 is V ' ref1-V
f1below (with reference to Fig. 3).
In addition, following formula (5) can be derived by above-mentioned formula (2) ~ formula (4).
Vanode=Vcc-Vcathode（5）
Therefore, in order to the voltage waveform Vmax in alternating voltage Vu, Vv, Vw of each phase and the consistency guaranteeing overcurrent suppression (OCS) grade between voltage waveform Vmin part, namely, the consistency of the comparison scale between the magnitude of voltage Vcathode exported in order to ensure the common cathode end Tcathode from the rectification part 2 and magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2, Vref1 and V ' ref1 preferably meets following formula (6).
V’ref1=Vcc-Vref1（6）
Also have, OCT judging part 4 comprises: the 3rd comparator 41, it is made up of operational amplifier, receive the magnitude of voltage Vcathode that exports from the common cathode end Tcathode of rectification part 2 and compare with the OCT reference voltage value Vref2 preset, judging whether thus to start overcurrent blockade (OCT) function; 4th comparator 42, it is made up of operational amplifier, receive the magnitude of voltage Vanode that exports from the common anode end Tanode of rectification part 2 and compare with the 2nd OCT reference voltage value V ' ref2 preset, judging whether thus to start overcurrent blockade (OCT) function.Now, in the 3rd comparator 41, whether the magnitude of voltage Vcathode that multilevel iudge exports from the common cathode end Tcathode of rectification part 2 is OCT more than the reference voltage value Vref2 preset, and whether the magnitude of voltage of voltage waveform Vmax that namely multilevel iudge inputs to rectification part 2 is Vref2+V
f1above, and in the 4th comparator 42, whether the magnitude of voltage Vanode that multilevel iudge exports from the common anode end Tanode of rectification part 2 is the 2nd OCT reference voltage value V ' below the ref1 preset, and whether the magnitude of voltage of voltage waveform Vmin that namely multilevel iudge inputs to rectification part 2 is V ' ref2-V
f1below (with reference to Fig. 3).
In view of above-mentioned formula (5), in order to the voltage waveform Vmax in alternating voltage Vu, Vv, Vw of each phase and the consistency guaranteeing overcurrent blockade (OCT) grade between voltage waveform Vmin part, Vref2 and V ' ref2 preferably meets following formula (7).
V’ref2=Vcc-Vref2（7）
Now, the magnitude relationship between above-mentioned each parameter is as follows.
Vcc＞Vref2＞Vref1＞Vcross＞Vcc/2＞V’cross＞V’ref1＞V’ref2＞0（8）
Below, with reference to Fig. 3, the action of the overcurrent sensing circuit of existing frequency-converter device is described.
First, alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage are applied to rectification part 2.
As mentioned above, even the alternating voltage of the arbitrary phase in alternating voltage Vu, Vv, Vw of each phase (such as, U phase voltage Vu) behavior of the alternating voltage (such as, V phase voltage Vv or W phase voltage Vw) of other phases can both be represented, so only observe the behavior of U phase voltage Vu at this.
With reference to Fig. 3, first observe the interval between crossover node a and crossover node b that magnitude of voltage (V) is Vcross.Be in application in alternating voltage Vu, Vv, Vw of each phase of the three-phase input voltage of rectification part 2, the part marked with heavy line of the waveform of U phase voltage Vu becomes the above-mentioned voltage waveform Vmax with maximum voltage value, now, only make the upside diode current flow be connected with U phase voltage Vu, the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is Vmax-V
f1.
Now, interval at T0 ~ T1, first comparator 31 multilevel iudge of OCS judging part 3 is that the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is less than the OCS reference voltage value Vref1 preset, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmax inputted to rectification part 2 is less than Vref1+V
f1.Simultaneously, 3rd comparator 41 of OCT judging part 4 also multilevel iudge is that the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is less than the OCT reference voltage value Vref2 preset, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmax inputted to rectification part 2 is less than Vref2+V
f1.Therefore, frequency-converter device does not start overcurrent and suppresses (OCS) function and overcurrent block (OCT) function and normally carry out action.
Interval at T1 ~ T2, first comparator 31 of OCS judging part 3 and the 3rd comparator 41 multilevel iudge of OCT judging part 4 are that the magnitude of voltage Vcathode that exports from the common cathode end Tcathode of rectification part 2 is less than at OCS more than the reference voltage value Vref1 preset the OCT reference voltage value Vref2 preset, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmax that inputs to rectification part 2 is at Vref1+V
f1above and be less than Vref2+V
f1.Therefore, frequency-converter device starts overcurrent and suppresses (OCS) function, and reduction frequency and output voltage reduce output current automatically.
Interval at T2 ~ T3, first comparator 31 of OCS judging part 3 and the 3rd comparator 41 multilevel iudge of OCT judging part 4 are that the magnitude of voltage Vcathode that exports from the common cathode end Tcathode of rectification part 2 is at OCS more than the reference voltage value Vref1 preset and OCT more than the reference voltage value Vref2 preset, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmax that inputs to rectification part 2 is at Vref1+V
f1above and Vref2+V
f1above.Therefore, frequency-converter device starts overcurrent and blocks (OCT) function, stops output carrying out teaching display stand protection.
In addition, the interval between crossover node b ' and crossover node c ' that magnitude of voltage (V) is V ' cross is then observed.Be in application in alternating voltage Vu, Vv, Vw of each phase of the three-phase input voltage of rectification part 2, the part marked with heavy line of the waveform of U phase voltage Vu becomes the above-mentioned waveform Vmin with minimum amount of voltage that, now, only make the downside diode current flow be connected with U phase voltage Vu, the magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2 is Vmin+V
f1.
Now, interval at T ' 0 ~ T ' 1, second comparator 32 multilevel iudge of OCS judging part 3 is the 2nd OCS reference voltage value V ' more than the ref1 that the magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2 is presetting, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmin that inputs to rectification part 2 is at V ' ref1-V
f1above.Simultaneously, 4th comparator 42 of OCT judging part 4 also multilevel iudge is the 2nd OCT reference voltage value V ' more than the ref2 that the magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2 is presetting, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmin that inputs to rectification part 2 is at V ' ref2-V
f1above.Therefore, startup overcurrent in frequency-converter device portion suppresses (OCS) function and overcurrent block (OCT) function and normally carry out action.
Interval at T ' 1 ~ T ' 2, second comparator 32 of OCS judging part 3 and the 4th comparator 42 multilevel iudge of OCT judging part 4 are that the magnitude of voltage Vanode that exports from the common anode end Tanode of rectification part 2 is greater than at the 2nd OCS reference voltage value V ' below the ref1 preset the 2nd OCT reference voltage value V ' ref2 preset, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmin that inputs to rectification part 2 is at V ' ref1-V
f1below and be greater than V ' ref2-V
f1.Therefore, frequency-converter device starts overcurrent and suppresses (OCS) function, and reduction frequency and output voltage reduce output current automatically.
Interval at T ' 2 ~ T ' 3, second comparator 32 of OCS judging part 3 and the 4th comparator 42 multilevel iudge of OCT judging part 4 are that the magnitude of voltage Vanode that exports from the common anode end Tanode of rectification part 2 is at the 2nd OCS reference voltage value V ' below the ref1 preset and the 2nd OCT reference voltage value V ' below the ref2 preset, that is, multilevel iudge is that the magnitude of voltage of voltage waveform Vmin that inputs to rectification part 2 is at V ' ref1-V
f1below and Vref2-V
f1below.Therefore, frequency-converter device starts overcurrent and blocks (OCT) function, stops output carrying out teaching display stand protection.
From the above, in the overcurrent sensing circuit of existing frequency-converter device, the output current of the frequency-converter device detected by current sensor etc. is converted to voltage signal to obtain three-phase input voltage, and by rectification part 2 to this three-phase input voltage carry out diode rectification and respectively with reference voltage value Vref1 and the V ' ref1 preset, Vref2 and V ' ref2 compares, and judges whether thus to start OCS/OCT function.If the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is more than the reference voltage value Vref1 preset, or be reference voltage value V ' below the ref1 preset from the magnitude of voltage Vanode that the common anode end Tanode of rectification part 2 exports, then start OCS function; If the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is more than the reference voltage value Vref2 preset, or be reference voltage value V ' below the ref1 preset from the magnitude of voltage Vanode that the common anode end Tanode of rectification part 2 exports, then start OCT function.Start OCS function, then frequency-converter device reduces frequency and output voltage automatically to reduce output current, and now, if current value raises further and starts OCT function, then frequency-converter device stops output carrying out teaching display stand protection.
Though such overcurrent suppressing method has the simple advantage of circuit, but use 4 expensive operational amplifiers to form 4 comparators, the manufacturing cost that thus there is circuit uprises and size for the printed circuit board (PCB) (PCB) forming overcurrent sensing circuit becomes large shortcoming.
Summary of the invention
The present invention proposes to solve the problem, and the object of the present invention is to provide a kind of low cost of manufacture and for the little overcurrent sensing circuit of the size of the PCB forming overcurrent sensing circuit and the frequency-converter device with this overcurrent sensing circuit.
Feature for the overcurrent sensing circuit of the present invention realizing above-mentioned purpose is, comprising: voltage input part, and it is for inputting the input voltage be converted to the output current of the frequency-converter device detected; Rectification part, it has the diode array for forming full-wave rectifying circuit, for carrying out rectification to the above-mentioned input voltage received from above-mentioned voltage input part; Inverse transformation part, it carries out reciprocal transformation for the voltage waveform received the common anode termination from above-mentioned rectification part; Magnitude of voltage selection portion, it, at the voltage waveform exported from the common cathode end of above-mentioned rectification part with from the voltage waveform that above-mentioned inverse transformation part exports, optionally makes the little voltage waveform of magnitude of voltage pass through; Overcurrent suppresses judging part, and it judges whether to start overcurrent inhibit feature according to the magnitude of voltage received from above-mentioned magnitude of voltage selection portion; Overcurrent blocks judging part, and it judges whether to start overcurrent lock-out facility according to the magnitude of voltage received from above-mentioned magnitude of voltage selection portion.
The feature of above-mentioned overcurrent sensing circuit is, the scope of the magnitude of voltage of each phase of the above-mentioned input voltage received from above-mentioned voltage input part is 0 ~+Vcc, and the voltage waveform of above-mentioned each phase with Vcc/2 axle for reference symmetry.
The feature of above-mentioned overcurrent sensing circuit is, is applied with high voltage Vcc at the common anode end of above-mentioned rectification part.
The feature of above-mentioned overcurrent sensing circuit is, above-mentioned inverse transformation part is used for the voltage waveform reciprocal transformation that the common anode termination from above-mentioned rectification part receives being for benchmark and the laterally zygomorphic waveform of this voltage waveform received from the common anode termination of above-mentioned rectification part with Vcc/2 axle.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned inverse transformation part is made up of the differential amplifier comprising operational amplifier, the in-phase input end of this operational amplifier is applied with voltage vcc/2, between inverting input and the common anode end of above-mentioned rectification part, be connected with the first resistance, between output and the end of the anti-phase input side of above-mentioned first resistance, be connected with the second resistance that the resistance value of resistance value and above-mentioned first resistance is identical.
In above-mentioned overcurrent sensing circuit, preferably, voltage vcc/2 putting on the in-phase input end of above-mentioned operational amplifier are obtained by electric resistance partial pressure.
In above-mentioned overcurrent sensing circuit, preferably, 2 diodes that the above-mentioned magnitude of voltage selection portion same degree that comprises forward voltage drop tube value is high.
In above-mentioned overcurrent sensing circuit, preferably, the positive pole of a diode in above-mentioned 2 diodes is connected with the common cathode end of above-mentioned rectification part, the positive pole of another diode is connected with the output of above-mentioned first operational amplifier, and the negative pole of each diode is connected and forms the common cathode end of above-mentioned magnitude of voltage selection portion.
In above-mentioned overcurrent sensing circuit, preferably, the common cathode end of above-mentioned rectification part is provided with compensating resistance, this compensating resistance is used for making portion of electrical current branch to ground wire, guarantees the consistency of the forward voltage drop tube value of above-mentioned 2 diodes.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent suppresses judging part to comprise overcurrent and suppresses comparator, and this overcurrent suppresses comparator receive the magnitude of voltage from above-mentioned magnitude of voltage selection portion output and suppress reference voltage value to compare with the overcurrent preset.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent suppress judging part to suppress comparator by above-mentioned overcurrent whether magnitude of voltage that multilevel iudge exports from above-mentioned magnitude of voltage selection portion is that the overcurrent preset suppresses more than reference voltage value, judge whether startup overcurrent inhibit feature thus.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent is blocked judging part and is comprised overcurrent blockade comparator, and this overcurrent blockade comparator receives the magnitude of voltage from above-mentioned magnitude of voltage selection portion output and blocks reference voltage value with the overcurrent preset and compares.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent is blocked judging part and is blocked comparator by above-mentioned overcurrent and come whether the magnitude of voltage that multilevel iudge exports from above-mentioned magnitude of voltage selection portion is that the overcurrent preset blocks more than reference voltage value, judges whether startup overcurrent lock-out facility thus.
Feature for the frequency-converter device of the present invention realizing above-mentioned purpose is to have above-mentioned overcurrent sensing circuit.
According to the present invention, then compared with the overcurrent sensing circuit of existing frequency-converter device, less with an expensive operational amplifier, so manufacturing cost can not only be reduced, but also can reduce the size of the PCB for forming overcurrent sensing circuit.
Accompanying drawing explanation
Fig. 1 shows the figure of the overcurrent sensing circuit of existing frequency-converter device.
Fig. 2 is the oscillogram of the alternating voltage of each phase of the three-phase input voltage inputted from the voltage input part of the overcurrent sensing circuit of frequency-converter device.
Fig. 3 is the oscillogram of the three-phase input voltage of the action of overcurrent sensing circuit for illustration of existing frequency-converter device.
Fig. 4 shows the figure of the overcurrent sensing circuit of frequency-converter device of the present invention.
Fig. 5 is the oscillogram of the reciprocal transformation result of the inverse transformation part of overcurrent sensing circuit for illustration of frequency-converter device of the present invention.
Fig. 6 is the oscillogram of the action of overcurrent sensing circuit for illustration of frequency-converter device of the present invention.
The explanation of Reference numeral
1 voltage input part
2 rectification part
3 OCS judging parts
31 first comparator 32 second comparators
4 OCT judging parts
41 the 3rd comparator 42 the 4th comparators
30 inverse transformation part
301 operational amplifier R1 first resistance R2 second resistance
40 compensating resistances
R1 the 3rd resistance
50 magnitude of voltage selection portions
60 OCS judging parts
601 OCS comparators
70 OCT judging parts
701 OCT comparators
Embodiment
Below, with reference to accompanying drawing, specific embodiments of the invention are described in detail.
Fig. 4 shows the figure of the overcurrent sensing circuit of frequency-converter device of the present invention.
As shown in Figure 4, the overcurrent sensing circuit of frequency-converter device of the present invention comprises: voltage input part 1, and it is for inputting three-phase input voltage, and this three-phase input voltage detects the output current of frequency-converter device and is converted to voltage signal and obtains; Rectification part 2, it has the diode array for forming three-phase full wave rectifier circuit, for carrying out rectification to the three-phase input voltage received from overvoltage input part 1; Inverse transformation part 30, it carries out reciprocal transformation for the voltage waveform received the common anode end Tanode of the diode array from rectification part 2; Magnitude of voltage selection portion 50, the voltage waveform that its common cathode end Tcathode in the diode array from rectification part 2 exports and from inverse transformation part 30 export voltage waveform, optionally make the little voltage waveform of magnitude of voltage pass through; OCS judging part 60, according to the magnitude of voltage received from magnitude of voltage selection portion 50, it judges whether that starting overcurrent suppresses (OCS) function; OCT judging part 70, according to the magnitude of voltage received from magnitude of voltage selection portion 50, it judges whether that starting overcurrent blocks (OCT) function.
Comparison diagram 4 and Fig. 1 known, the voltage input part 1 in the overcurrent sensing circuit of frequency-converter device of the present invention and the overcurrent sensing circuit of existing frequency-converter device and the structure of rectification part 2 identical.Therefore, described all the elements about the voltage input part 1 in the overcurrent sensing circuit of existing frequency-converter device and rectification part 2 above, obviously the voltage input part 1 in the overcurrent sensing circuit of frequency-converter device of the present invention and rectification part 2 can be applicable to respectively, so no longer repeat explanation at this.
Inverse transformation part 30 is made up of the differential amplifier comprising operational amplifier 301, the in-phase input end of this operational amplifier 301 is applied with voltage vcc/2, between the common anode end Tanode of the diode array of inverting input and rectification part 2, be connected with the first resistance R1, between the end of the anti-phase input side of output and the first resistance R1, be connected with the second resistance R2.
In inverse transformation part 30, realize voltage vcc/2 be applied on in-phase input end by electric resistance partial pressure.Further, as the first resistance R1 identical with the resistance value of the second resistance R2 (that is, R1=R2), according to the known relation between each parameter of differential amplifier, the magnitude of voltage Vo exported can be shown from the output of operational amplifier 301 by following formula (9).
Vo=（R1+R2）/R1×Vcc/2-R2/R1×Vanode=Vcc-Vanode（9）
Substitute into above-mentioned formula (2), (3) and (4) to above formula (9), then can derive following formula (10).
Vo=Vcc-Vmin-V
F1=Vmax-V
F1=Vcathode（10）
From above formula (10) and (5), inverse transformation part 30 has following function: the voltage waveform Vanode reciprocal transformation received by the common anode end Tanode of the diode array from rectification part 2 is for benchmark and the laterally zygomorphic output waveform Vo(=Vcathode of this voltage waveform Vanode with Vcc/2 axle).
And, if formula (2) ~ (3) are also taken into account, then also can think that inverse transformation part 30 has following function: voltage waveform Vmin alternating voltage Vu, Vv, Vw of each phase being arranged in the three-phase input voltage of arbitrary enough little time interval (or between phase region) with the alternating voltage of the phase of minimum amount of voltage that, reciprocal transformation is for benchmark and the laterally zygomorphic voltage waveform of this voltage waveform Vmin and voltage waveform Vmax(=Vcc-Vmin with Vcc/2 axle).
Fig. 5 is the oscillogram of the reciprocal transformation result of inverse transformation part 30 for illustration of the overcurrent sensing circuit of frequency-converter device of the present invention, and the voltage waveform Vmin that alternating voltage Vu, Vv, Vw of showing each phase of the three-phase input voltage being arranged in arbitrary enough little time interval (or between phase region) have the alternating voltage of the phase of minimum amount of voltage that is reversed the state that transformation component 30 reciprocal transformation is voltage waveform Vcc-Vmin.In addition, for convenience of explanation, also also show not via the voltage waveform Vmax of inverse transformation part 30.
Also have, with reference to the explanation about the overcurrent sensing circuit of existing frequency-converter device, in the overcurrent sensing circuit of frequency-converter device of the present invention, the alternating voltage Vu of each phase of three-phase input voltage, Vv, phase difference between Vw is 120 degree, the alternating voltage Vu of each phase, Vv, the sinusoidal wave period of Vw and amplitude identical, even so the alternating voltage Vu of each phase, Vv, the alternating voltage of the arbitrary phase in Vw (such as, U phase voltage Vu) also can represent the alternating voltage of other phases (such as, V phase voltage Vv or W phase voltage Vw) behavior, thus illustrate only the waveform portion of U phase voltage Vu in Figure 5.
But actual waveform is not desirable sine wave, but comprises the sine wave (the heavy line part in Fig. 5) of high-frequency harmonic composition.And, except the waveform portion of illustrated U phase voltage Vu, also to exist and the waveform portion of this U phase voltage Vu has the phase difference of 120 degree and the waveform portion of cycle and the identical V phase voltage Vv of amplitude and W phase voltage Vw respectively, thus the waveform of reality is the respective voltage waveform Vmax of alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage and alternating voltage Vu, Vv, Vw voltage waveform Vmin separately of each phase be reversed transformation component 30 reciprocal transformation after each voltage waveform Vcc-Vmin to alternate the waveform intersected to form.Fig. 6 shows such waveform.
Fig. 6 is the oscillogram of the action of overcurrent sensing circuit for illustration of frequency-converter device of the present invention, and alternating voltage Vu, Vv, Vw voltage waveform Vmin separately of the respective voltage waveform Vmax of alternating voltage Vu, Vv, Vw of also show each phase of three-phase input voltage and each phase is reversed each voltage waveform Vcc-Vmin after transformation component 30 reciprocal transformation.As shown in the drawing, alternating voltage Vu, Vv, Vw of each phase voltage waveform Vmax is separately about V at its magnitude of voltage " position of cross intersects with the voltage waveform Vcc-Vmin after the voltage waveform Vmin of other adjacent phases is reversed transformation component 30 reciprocal transformation.In other words, alternating voltage Vu, Vv, Vw voltage waveform Vmin separately of the respective voltage waveform Vmax of alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage and each phase is reversed each voltage waveform Vcc-Vmin after transformation component 30 reciprocal transformation, is about V with its magnitude of voltage " each crossover node of cross is that benchmark alternately has maximum voltage value (the heavy line part in Fig. 6).That is, the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 and alternately there is maximum voltage value from the magnitude of voltage Vo that the output of inverse transformation part 30 exports.
Return to Fig. 4, magnitude of voltage selection portion 50 comprises forward voltage drop tube V
f22 diodes that the same degree be worth is high, the positive pole of one of them diode is connected with the common cathode end Tcathode of rectification part 2, the positive pole of another diode is connected with the output of inverse transformation part 30, and the negative pole of each diode is connected and forms the common cathode end of magnitude of voltage selection portion 50.
As the conducting principle of the diode array of rectification part 2, magnitude of voltage selection portion 50 only makes the diode current flow being applied with specific voltage waveform, this specific voltage waveform refers to, at the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 and magnitude of voltage is large from the magnitude of voltage Vo that the output of inverse transformation part 30 exports voltage waveform.That is, at the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 with from the magnitude of voltage Vo that the output of inverse transformation part 30 exports, magnitude of voltage selection portion 50 optionally only makes the large voltage waveform of magnitude of voltage pass through.
In addition, when the output voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is by a diode magnitude of voltage selection portion 50, magnitude of voltage can decline V
f2, cause this magnitude of voltage to become Vcathode-V
f2=Vmax-V
f1-V
f2.And, when the output voltage Vo exported from the output of inverse transformation part 30 is by another diode magnitude of voltage selection portion 50, magnitude of voltage decline V
f2, cause this magnitude of voltage to become Vo-V
f2=Vmax-V
f1-V
f2.
It can thus be appreciated that the voltage waveform Vmax of alternating voltage Vu, Vv, Vw of each phase have passed the magnitude of voltage that magnitude of voltage after a diode of magnitude of voltage selection portion 50 and the voltage waveform Vmin of alternating voltage Vu, Vv, Vw of each phase have passed after another diode of inverse transformation part 30 and magnitude of voltage selection portion 50 and becomes completely the same.Therefore; the suppression grade of (OCS) function and overcurrent is suppressed to block the consistency of the blockade grade of (OCT) function in order to ensure the overcurrent based on the magnitude of voltage after 2 diodes respectively by magnitude of voltage selection portion 50; preferably, the maximum voltage value in the magnitude of voltage of these 2 parts should be selected compare to judge process.
For this reason, utilize magnitude of voltage selection portion 50, in the voltage waveform Vo that the voltage waveform Vmin of alternating voltage Vu, Vv, Vw of the voltage waveform Vmax of alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage and each phase of three-phase input voltage is reversed after transformation component 30 reciprocal transformation, select maximum voltage value to form selection voltage waveform, and export this selection voltage waveform from the common cathode end of magnitude of voltage selection portion 50.Select the magnitude of voltage Vselect of voltage waveform can be illustrated by following formula (11).
Vselect=Vmax-V
F1-V
F2（11）
Further, due to the forward voltage drop tube V of each diode of magnitude of voltage selection portion 50
f2depend on the current value flowing through this diode, so in order to make the current value of 2 of overvoltage value selection portion 50 diodes consistent, preferably arrange at the common cathode end Tcathode of rectification part 2 compensating resistance 40 be made up of the 3rd resistance R3, this compensating resistance 40 branches to ground wire to guarantee the consistency of the forward voltage drop tube of 2 diodes for making portion of electrical current.3rd resistance R3 elects variable resistance as.
OCS judging part 60 comprises the OCS comparator 601 be made up of operational amplifier, for receiving the magnitude of voltage Vselect that exports from the common cathode end of magnitude of voltage selection portion 50 and comparing with the OCS reference voltage value Vref3 preset.Now, by OCS comparator 601, OCS judging part 60 comes whether the magnitude of voltage Vselect that multilevel iudge exports from the common cathode end of magnitude of voltage selection portion 50 is OCS more than the reference voltage value Vref3 preset, that is, whether the voltage waveform Vmax magnitude of voltage partly that multilevel iudge inputs to rectification part 2 is Vref3+V
f1+ V
f2whether the magnitude of voltage above or to the voltage waveform Vmin part of rectification part 2 input is Vref3-V
f1-V
f2below (with reference to Fig. 6), judge whether that starting overcurrent suppresses (OCS) function thus.
Further, OCT judging part 70 comprises the OCT comparator 701 be made up of operational amplifier, for receiving the magnitude of voltage Vselect that exports from the common cathode end of magnitude of voltage selection portion 50 and comparing with the OCT reference voltage value Vref4 preset.Now, by OCT comparator 701, OCT judging part 70 comes whether the magnitude of voltage Vselect that multilevel iudge exports from the common cathode end of magnitude of voltage selection portion 50 is OCT more than the reference voltage value Vref4 preset, that is, whether the voltage waveform Vmax magnitude of voltage partly that multilevel iudge inputs to rectification part 2 is Vref4+V
f1+ V
f2whether the magnitude of voltage above or to the voltage waveform Vmin part of rectification part 2 input is Vref4-V
f1-V
f2below (with reference to Fig. 6), judge whether that starting overcurrent blocks (OCT) function thus.
Now, the magnitude relationship between above-mentioned each parameter is as follows.
Vcc＞Vref4＞Vref3＞V”cross＞Vcross＞Vcc/2（12）
Below, with reference to Fig. 2, Fig. 3 and Fig. 6, the action of overcurrent sensing circuit of the present invention is described.
First, alternating voltage Vu, Vv, Vw of each phase of three-phase input voltage are applied to rectification part 2.
As shown in Figure 2, in alternating voltage Vu, Vv, Vw of each phase, the alternating voltage of a certain phase has the time interval of maximum voltage value (or between phase region; Interval such as between crossover node b and c), the alternating voltage being overlapped in another phase mutually adjacent with this has the time interval of minimum amount of voltage that (or between phase region; Interval such as between crossover node a ' and b ' or the interval between crossover node b ' and c ').In other words, with regard to arbitrary enough little time interval (or between phase region), while in alternating voltage Vu, Vv, Vw of each phase, the alternating voltage of a certain phase has maximum voltage value, the alternating voltage of another phase mutually adjacent with this has minimum amount of voltage that.
In time interval (or between phase region) between crossover node a and a ', in alternating voltage Vu, Vv, the Vw of each phase putting on rectification part 2, the waveform Vmax of U phase voltage Vu has maximum voltage value, now, only make the upside diode current flow be connected with U phase voltage Vu, the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is Vcathode=Vmax-V
f1.Simultaneously, put on rectification part 2 three-phase input voltage each phase alternating voltage Vu, Vv, Vw in, the waveform Vmin of V phase voltage Vv has minimum amount of voltage that, now, only make the downside diode current flow be connected with V phase voltage Vv, the magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2 is Vmin+V
f1.
The magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 is directly inputted into a diode of magnitude of voltage selection portion 50.
The magnitude of voltage Vanode exported from the common anode end Tanode of rectification part 2 inputs to inverse transformation part 30, and exports the output waveform Vo(=Vcc-Vmin-V after reciprocal transformation from the output of this inverse transformation part 30
f1=Vmax-V
f1) (the voltage waveform Vcc-Vmin with reference in Fig. 5).
From the voltage waveform Vo(=Vcc-Vmin-V that the output of inverse transformation part 30 exports
f1) input to another diode of magnitude of voltage selection portion 50.
Magnitude of voltage selection portion 50 is formed at the magnitude of voltage Vcathode exported from the common cathode end Tcathode of rectification part 2 and the voltage waveform of selecting magnitude of voltage large from the magnitude of voltage Vo that the output of inverse transformation part 30 exports and selects voltage waveform Vselect, and exports this selection voltage waveform Vselect from the common cathode end of magnitude of voltage selection portion 50.
The magnitude of voltage Vselect exported from the common cathode end of magnitude of voltage selection portion 50 inputs to OCS judging part 60.Whether OCS judging part 60 multilevel iudge magnitude of voltage Vselect is OCS more than the reference voltage value Vref3 preset, that is, whether the voltage waveform Vmax magnitude of voltage partly that multilevel iudge inputs to rectification part 2 is Vref3+V
f1+ V
f2whether the magnitude of voltage above or to the voltage waveform Vmin part of rectification part 2 input is Vref3-V
f1-V
f2below (with reference to Fig. 6).
If magnitude of voltage Vselect is less than the OCS reference voltage value Vref3 preset, then frequency-converter device does not start overcurrent and suppresses (OCS) function and overcurrent block (OCT) function and normally carry out action.
If magnitude of voltage Vselect is OCS more than the reference voltage value Vref3 preset, then frequency-converter device starts overcurrent suppression (OCS) function, and reduction frequency and output voltage reduce output current automatically.
In addition.The magnitude of voltage Vselect exported from the common cathode end of magnitude of voltage selection portion 50 also inputs to OCT judging part 70.Whether OCT judging part 70 multilevel iudge magnitude of voltage Vselect is OCT more than the reference voltage value Vref4 preset, that is, whether the voltage waveform Vmax magnitude of voltage partly that multilevel iudge inputs to rectification part 2 is Vref4+V
f1+ V
f2whether the magnitude of voltage above or to the voltage waveform Vmin part of rectification part 2 input is Vref4-V
f1-V
f2below (with reference to Fig. 6).
If magnitude of voltage Vselect is less than the OCT reference voltage value Vref4 preset, then according to the multilevel iudge result of OCS judging part 60, frequency-converter device judges whether that starting overcurrent suppresses (OCS) function.
If magnitude of voltage Vselect is OCT more than the reference voltage value Vref4 preset, then frequency-converter device starts overcurrent blockade (OCT) function, stops output carrying out teaching display stand protection.
Between crossover node a ' and b, between b and b ', between b ' and c, between c and c ', between c ' and d, in equal time interval (or between phase region), overcurrent sensing circuit of the present invention also carries out action, so no longer repeat explanation at this in the mode that the method for operating in the time interval (or between phase region) between crossover node a and a ' as above is similar.
Above with reference to accompanying drawing, overcurrent sensing circuit of the present invention and the frequency-converter device with this overcurrent sensing circuit are illustrated, but these contents are most preferred embodiments of the present invention, can not be considered as limitation of the invention.
Such as, in above embodiment, although illustrate the overcurrent sensing circuit for three phase variable frequency apparatus, but overcurrent sensing circuit of the present invention also goes for the frequency-converter device of more than three phases, for this reason, as long as rectification part 2 to be configured to the full-wave rectifying circuit of the phase corresponding to more than three.
Therefore, for general technical staff of the technical field of the invention, not departing from the various deformation and imitation implemented in the scope of the category of technological thought of the present invention, obviously all belong to protection scope of the present invention.
Claims (17)
1. an overcurrent sensing circuit for frequency-converter device, is characterized in that, comprising:
Voltage input part, it is for inputting the input voltage be converted to the output current of the frequency-converter device detected;
Rectification part, it has the diode array for forming full-wave rectifying circuit, for carrying out rectification to the above-mentioned input voltage received from above-mentioned voltage input part;
Inverse transformation part, it carries out reciprocal transformation for the voltage waveform received the common anode termination from above-mentioned rectification part;
Magnitude of voltage selection portion, it, at the voltage waveform exported from the common cathode end of above-mentioned rectification part with from the voltage waveform that above-mentioned inverse transformation part exports, optionally makes the large voltage waveform of magnitude of voltage pass through;
Overcurrent suppresses judging part, and it judges whether to start overcurrent inhibit feature according to the magnitude of voltage received from above-mentioned magnitude of voltage selection portion;
Overcurrent blocks judging part, and it judges whether to start overcurrent lock-out facility according to the magnitude of voltage received from above-mentioned magnitude of voltage selection portion.
2. the overcurrent sensing circuit of frequency-converter device according to claim 1, it is characterized in that, the scope of the magnitude of voltage of each phase of the above-mentioned input voltage received from above-mentioned voltage input part is 0 ~+Vcc, and the voltage waveform of above-mentioned each phase with Vcc/2 axle for reference symmetry.
3. the overcurrent sensing circuit of frequency-converter device according to claim 2, is characterized in that, is applied with high voltage Vcc at the common anode end of above-mentioned rectification part.
4. the overcurrent sensing circuit of frequency-converter device according to claim 3, it is characterized in that, above-mentioned inverse transformation part is used for the voltage waveform reciprocal transformation that the common anode termination from above-mentioned rectification part receives being for benchmark and the laterally zygomorphic waveform of this voltage waveform received from the common anode termination of above-mentioned rectification part with Vcc/2 axle.
5. the overcurrent sensing circuit of frequency-converter device according to claim 3, it is characterized in that, above-mentioned inverse transformation part is made up of the differential amplifier comprising operational amplifier, the in-phase input end of this operational amplifier is applied with voltage vcc/2, between inverting input and the common anode end of above-mentioned rectification part, be connected with the first resistance, between output and the end of the anti-phase input side of above-mentioned first resistance, be connected with the second resistance that the resistance value of resistance value and above-mentioned first resistance is identical.
6. the overcurrent sensing circuit of frequency-converter device according to claim 5, is characterized in that, voltage vcc/2 putting on the in-phase input end of above-mentioned operational amplifier are obtained by electric resistance partial pressure.
7. the overcurrent sensing circuit of the frequency-converter device according to any one in Claims 1-4, is characterized in that, 2 diodes that the same degree that above-mentioned magnitude of voltage selection portion comprises forward voltage drop tube value is high.
8. the overcurrent sensing circuit of the frequency-converter device according to claim 5 or 6, is characterized in that, 2 diodes that the same degree that above-mentioned magnitude of voltage selection portion comprises forward voltage drop tube value is high.
9. the overcurrent sensing circuit of frequency-converter device according to claim 8, it is characterized in that, the positive pole of a diode in above-mentioned 2 diodes is connected with the common cathode end of above-mentioned rectification part, the positive pole of another diode is connected with the output of the first operational amplifier, and the negative pole of each diode is connected and forms the common cathode end of above-mentioned magnitude of voltage selection portion.
10. the overcurrent sensing circuit of frequency-converter device according to claim 7, it is characterized in that, the common cathode end of above-mentioned rectification part is provided with compensating resistance, and this compensating resistance is used for making portion of electrical current branch to ground wire, guarantees the consistency of the forward voltage drop tube value of above-mentioned 2 diodes.
The overcurrent sensing circuit of 11. frequency-converter devices according to claim 8, it is characterized in that, the common cathode end of above-mentioned rectification part is provided with compensating resistance, and this compensating resistance is used for making portion of electrical current branch to ground wire, guarantees the consistency of the forward voltage drop tube value of above-mentioned 2 diodes.
The overcurrent sensing circuit of 12. frequency-converter devices according to claim 9, it is characterized in that, the common cathode end of above-mentioned rectification part is provided with compensating resistance, and this compensating resistance is used for making portion of electrical current branch to ground wire, guarantees the consistency of the forward voltage drop tube value of above-mentioned 2 diodes.
The overcurrent sensing circuit of 13. frequency-converter devices according to any one in claim 1 to 6, it is characterized in that, above-mentioned overcurrent suppresses judging part to comprise overcurrent and suppresses comparator, and this overcurrent suppresses comparator receive the magnitude of voltage from above-mentioned magnitude of voltage selection portion output and suppress reference voltage value to compare with the overcurrent preset.
The overcurrent sensing circuit of 14. frequency-converter devices according to claim 13, it is characterized in that, above-mentioned overcurrent suppress judging part to suppress comparator by above-mentioned overcurrent whether magnitude of voltage that multilevel iudge exports from above-mentioned magnitude of voltage selection portion is that the overcurrent preset suppresses more than reference voltage value, judge whether startup overcurrent inhibit feature thus.
The overcurrent sensing circuit of 15. frequency-converter devices according to any one in claim 1 to 6, it is characterized in that, above-mentioned overcurrent is blocked judging part and is comprised overcurrent blockade comparator, and this overcurrent blockade comparator receives the magnitude of voltage from above-mentioned magnitude of voltage selection portion output and blocks reference voltage value with the overcurrent preset and compares.
The overcurrent sensing circuit of 16. frequency-converter devices according to claim 15, it is characterized in that, above-mentioned overcurrent is blocked judging part and is blocked comparator by above-mentioned overcurrent and come whether the magnitude of voltage that multilevel iudge exports from above-mentioned magnitude of voltage selection portion is that the overcurrent preset blocks more than reference voltage value, judges whether startup overcurrent lock-out facility thus.
17. 1 kinds of frequency-converter devices, is characterized in that, have the overcurrent sensing circuit described in any one in claim 1 to 16.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1045667A (en) * | 1989-03-14 | 1990-09-26 | 科恩升降机股份有限公司 | Bridge circuit overvoltage protection and tightly be brake control |
| GB2244876A (en) * | 1989-03-02 | 1991-12-11 | Power Management Int | A.C. Power controller with short circuit and overload protection |
| CN2497460Y (en) * | 2001-05-24 | 2002-06-26 | 郑碎挺 | Self-protective fully-automatic over-under voltage protector |
| CN101141058A (en) * | 2007-09-14 | 2008-03-12 | 田忠孝 | Distribution circuit electric voltage over-deviation protectors |
| CN101557162A (en) * | 2009-03-11 | 2009-10-14 | 西安民展微电子有限公司 | Overvoltage protection circuit used in power factor corrector and power factor corrector |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009165288A (en) * | 2008-01-08 | 2009-07-23 | Sanken Electric Co Ltd | Switching power supply device |
-
2012
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2244876A (en) * | 1989-03-02 | 1991-12-11 | Power Management Int | A.C. Power controller with short circuit and overload protection |
| CN1045667A (en) * | 1989-03-14 | 1990-09-26 | 科恩升降机股份有限公司 | Bridge circuit overvoltage protection and tightly be brake control |
| CN2497460Y (en) * | 2001-05-24 | 2002-06-26 | 郑碎挺 | Self-protective fully-automatic over-under voltage protector |
| CN101141058A (en) * | 2007-09-14 | 2008-03-12 | 田忠孝 | Distribution circuit electric voltage over-deviation protectors |
| CN101557162A (en) * | 2009-03-11 | 2009-10-14 | 西安民展微电子有限公司 | Overvoltage protection circuit used in power factor corrector and power factor corrector |
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