CN103078482A - 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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- CN103078482A CN103078482A CN2012104069789A CN201210406978A CN103078482A CN 103078482 A CN103078482 A CN 103078482A CN 2012104069789 A CN2012104069789 A CN 2012104069789A CN 201210406978 A CN201210406978 A CN 201210406978A CN 103078482 A CN103078482 A CN 103078482A
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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 device that comes the speed of regulating electric machine by adjusting 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, high efficiency, the advantage such as easy to use.
Utilize frequency-converter device to carry out speed governing, motor is moved under energy-conservation rotating speed, but also can increase substantially the control precision of motor speed, thereby the people can improve processing quality and production efficiency.
The load of frequency-converter device mainly is motor.In case motor load is excessive even stall, if frequency-converter device is not taked safeguard measure, can causes that frequency-converter device is overheated and break down.Therefore, existing frequency-converter device has overcurrent sensing circuit, in order to take safeguard measure when such situation occurs.
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 used for the input three-phase input voltage, and this three-phase input voltage obtains the output current conversion of the frequency-converter device that utilizes current sensor etc. and detect; Rectification part 2, it has the diode row that consist of three-phase full wave rectifier circuit, is used for the three-phase input voltage that receives from voltage input part 1 is carried out rectification; OCS judging part 3, its basis judges whether to start overcurrent inhibition (OCS, Over Current Suppression) function from the common anode end Tanode of the diode row of rectification part 2 and the voltage that common cathode end Tcathode receives; OCT judging part 4, its basis judges whether to start overcurrent blockade (OCT, Over Current Trip) function from the common anode end Tanode of the diode row of rectification part 2 and the voltage that common cathode end Tcathode receives.
Fig. 2 is the oscillogram from the alternating voltage of each phase of the three-phase input voltage of voltage input part 1 input of the overcurrent sensing circuit of existing frequency-converter device.
As shown in Figure 2, that identical and each phase difference between mutually of cycle and amplitude is the sine waves of 120 degree from the waveform of alternating voltage Vu, the Vv of each phase of the three-phase input voltage of voltage input part 1 input of the overcurrent sensing circuit of existing frequency-converter device, Vw, the number range of the magnitude of voltage of each phase all 0～+ Vcc, the voltage waveform of each phase is symmetrical take the Vcc/2 axle as benchmark.Above-mentioned " voltage waveform take the Vcc/2 axle as benchmark symmetrical " refers to, voltage waveform with this voltage waveform along ω t axle+direction or-direction moves the half period and the voltage waveform that obtains is symmetrical up and down take the Vcc/2 axle as benchmark.
Though figure 2 illustrates alternating voltage Vu, Vv, the Vw of each phase of three-phase input voltage and be the situation of desirable sine wave, alternating voltage Vu, the Vv of each phase, the actual waveform of Vw are the sine waves that comprises the high-frequency harmonic composition.At this moment, the actual waveform of alternating voltage Vu, the Vv of each phase, Vw also is considered as belonging to the situation of " voltage waveform is symmetrical take the Vcc/2 axle as benchmark ".
As shown in Figure 2, the sine wave of the alternating voltage of arbitrary phase of three-phase input voltage, the position that becomes 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, the Vv of each phase of three-phase input voltage, Vw become Vcross take its magnitude of voltage each crossover node a, b, c, d alternately has maximum voltage value as benchmark, and each crossover node a ', the b ', c ', the d ' that become V ' cross take its magnitude of voltage alternately have the minimum voltage value as benchmark.In the situation that actual waveform contains the high-frequency harmonic composition, compare with the situation of desirable sine wave, except the position of each crossover node changing near the Vcross or near the V ' cross, alternating voltage Vu, the Vv of each phase of three-phase input voltage, Vw also alternately have maximum voltage value take near each crossover node the Vcross as benchmark, and alternately have the minimum voltage value take near each crossover node the V ' cross as benchmark.
Because the voltage waveform of each phase is symmetrical take the Vcc/2 axle as benchmark, set up formula (1).
V’cross=Vcc-Vcross（Vcc＞Vcross＞V’cross＞0） （1）
Vcathode=Vmax-V
F1 （2）
Wherein, Vmax refers to, in arbitrary enough little time interval (perhaps between phase region), has the waveform of alternating voltage of the phase of maximum voltage value among alternating voltage Vu, the Vv of each phase of three-phase input voltage, the Vw.Wherein, so-called time interval (perhaps between phase region) " enough little " refers to, in this time interval (perhaps between phase region), do not exist simultaneously the alternating voltage of the phase more than 2 to have maximum voltage value, perhaps do not exist simultaneously the alternating voltage of the phase more than 2 to have the minimum voltage value.
Also have, with regard to regard to 3 bottom diodes that the common anode end Tanode of rectification part 2 is connected, as shown in Figure 1, owing to being applied with high voltage Vcc at the common anode end Tanode of rectification part 2, thereby only make the diode current flow that is connected with the alternating voltage that in alternating voltage Vu, the Vv of each phase of three-phase input voltage, Vw, has the phase of minimum voltage value, at this moment, the magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output can be calculated by following formula (3).
Vanode=Vmin+V
F1 （3）
Wherein, Vmin refers to, in arbitrary enough little time interval (perhaps between phase region), has the waveform of alternating voltage of the phase of minimum voltage value among alternating voltage Vu, the Vv of each phase of three-phase input voltage, the Vw.
As mentioned above, alternating voltage Vu, the Vv of each phase of three-phase input voltage, the waveform of Vw are that identical and each phase difference between mutually of cycle and amplitude is the sine waves of 120 degree, the voltage waveform of each phase is symmetrical take the Vcc/2 axle as benchmark, and consider above formula (1), then can set up following formula (4).
Vmin=Vcc-Vmax （4）
Fig. 3 is the oscillogram be used to the three-phase input voltage of the action of the overcurrent sensing circuit that existing frequency-converter device is described.With regard to the overcurrent sensing circuit of existing frequency-converter device, because alternating voltage Vu, Vv, the phase difference between the Vw of each phase of three-phase input voltage are 120 degree, alternating voltage Vu, the Vv of each phase, Vw sinusoidal wave period and amplitude separately is identical, so even the alternating voltage of alternating voltage Vu, the Vv of each phase, the arbitrary phase among the Vw (for example, the alternating voltage that U phase voltage Vu) also can represent other phases (for example, V phase voltage Vv or W phase voltage Vw) behavior, thereby in Fig. 3, only show the waveform of the U phase voltage Vu among Fig. 2.Below, utilize the waveform of U phase voltage Vu that the action of overcurrent sensing circuit is described.Wherein, the waveform of voltage Vu is not desirable sine wave, but comprises the practical sinusoidal wave (the heavy line part among Fig. 3) of high-frequency harmonic composition.
With reference to Fig. 3, in the waveform of U phase voltage Vu, magnitude of voltage is that the above part (being positioned at the solid line part of the top of Vcc/2 axle) of Vcross is exactly above-mentioned voltage waveform Vmax, magnitude of voltage is that the following part (being positioned at the solid line part of the below of Vcc/2 axle) of V ' cross is exactly above-mentioned voltage waveform Vmin, and the voltage waveform Vmax of these 2 parts and Vmin can have influence on the magnitude of voltage Vcathode of common cathode end Tcathode of rectification part 2 and the magnitude of voltage Vanode of common anode end Tanode.
In addition, can derive following formula (5) by above-mentioned formula (2)～formula (4).
Vanode=Vcc-Vcathode（5）
Therefore, in order between alternating voltage Vu, the Vv of each phase, voltage waveform Vmax among the Vw and voltage waveform Vmin part, to guarantee that overcurrent suppresses the consistency of (OCS) grade, namely, in order to ensure from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output and from the consistency of the comparison scale between the magnitude of voltage Vanode of the common anode end Tanode output of rectification part 2, Vref1 and V ' ref1 preferably satisfy following formula (6).
V’ref1=Vcc-Vref1（6）
Also have, OCT judging part 4 comprises: the 3rd comparator 41, it is made of operational amplifier, reception compares from the magnitude of voltage Vcathode of the common cathode end Tcathode output of rectification part 2 and with a predefined OCT reference voltage value Vref2, judges whether thus to start overcurrent and blocks (OCT) function; The 4th comparator 42, it is made of operational amplifier, reception compares from the magnitude of voltage Vanode of the common anode end Tanode output of rectification part 2 and with predefined the 2nd OCT reference voltage value V ' ref2, judges whether thus to start overcurrent and blocks (OCT) function.At this moment, in the 3rd comparator 41, judge relatively whether from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output be more than the predefined OCT reference voltage value Vref2, judge relatively namely whether to the magnitude of voltage of the voltage waveform Vmax of rectification part 2 inputs be Vref2+V
F1Above, and in the 4th comparator 42, judge relatively whether from the magnitude of voltage Vanode of the common anode end Tanode of rectification part 2 output be below predefined the 2nd OCT reference voltage value V ' ref1, judge relatively namely whether to the magnitude of voltage of the voltage waveform Vmin of rectification part 2 inputs be V ' ref2-V
F1Below (with reference to Fig. 3).
In view of above-mentioned formula (5), in order to guarantee that between alternating voltage Vu, the Vv of each phase, voltage waveform Vmax among the Vw and voltage waveform Vmin part overcurrent blocks the consistency of (OCT) grade, Vref2 and V ' ref2 preferably satisfy following formula (7).
V’ref2=Vcc-Vref2（7）
At this moment, 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.
At first, alternating voltage Vu, Vv, the Vw with each phase of three-phase input voltage is applied to rectification part 2.
As mentioned above, even alternating voltage Vu, the Vv of each phase, among the Vw arbitrary phase alternating voltage (for example, U phase voltage Vu) can both represent the behavior of the alternating voltage (for example, V phase voltage Vv or W phase voltage Vw) of other phases, so only observe the behavior of U phase voltage Vu at this.
With reference to Fig. 3, observe first magnitude of voltage (V) and be the interval between the crossover node a of Vcross and the crossover node b.Be in application among alternating voltage Vu, Vv, the Vw of each phase of three-phase input voltage of rectification part 2, the part that marks with heavy line of the waveform of U phase voltage Vu becomes the above-mentioned voltage waveform Vmax with maximum voltage value, at this moment, only making the upside diode current flow that is connected with U phase voltage Vu, is Vmax-V from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output
F1
At this moment, interval at T0～T1, the first comparator 31 of OCS judging part 3 relatively is judged as magnitude of voltage Vcathode from the common cathode end Tcathode of rectification part 2 output less than a predefined OCS reference voltage value Vref1, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmax of rectification part 2 input less than Vref1+V
F1Simultaneously, the 3rd comparator 41 of OCT judging part 4 also relatively is judged as magnitude of voltage Vcathode from the common cathode end Tcathode of rectification part 2 output less than a predefined OCT reference voltage value Vref2, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmax of rectification part 2 input less than Vref2+V
F1Therefore, frequency-converter device does not start overcurrent inhibition (OCS) function and overcurrent blockade (OCT) function and normally moves.
Interval at T1～T2, the first comparator 31 of OCS judging part 3 and the 3rd comparator 41 of OCT judging part 4 relatively are judged as magnitude of voltage Vcathode from the common cathode end Tcathode of rectification part 2 output more than a predefined OCS reference voltage value Vref1 and less than a predefined OCT reference voltage value Vref2, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmax of rectification part 2 input at Vref1+V
F1Above and less than Vref2+V
F1Therefore, frequency-converter device starts overcurrent and suppresses (OCS) function, and reducing work frequency and output voltage reduce output current automatically.
Interval at T2～T3, the first comparator 31 of OCS judging part 3 and the 3rd comparator 41 of OCT judging part 4 relatively are judged as magnitude of voltage Vcathode from the common cathode end Tcathode of rectification part 2 output more than the predefined OCS reference voltage value Vref1 and more than the predefined OCT reference voltage value Vref2, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmax of rectification part 2 input at Vref1+V
F1Above and Vref2+V
F1Above.Therefore, frequency-converter device starts overcurrent and blocks (OCT) function, stops output and realizes self-protection.
In addition, then observe magnitude of voltage (V) and be the interval between the crossover node b ' of V ' cross and the crossover node c '.Be in application among alternating voltage Vu, Vv, the Vw of each phase of three-phase input voltage of rectification part 2, the part that marks with heavy line of the waveform of U phase voltage Vu becomes the above-mentioned waveform Vmin with minimum voltage value, at this moment, only making the downside diode current flow that is connected with U phase voltage Vu, is Vmin+V from the magnitude of voltage Vanode of the common anode end Tanode of rectification part 2 output
F1
At this moment, in T ' 0～T ' 1 interval, the second comparator 32 of OCS judging part 3 relatively is judged as magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output more than predefined the 2nd OCS reference voltage value V ' ref1, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmin of rectification part 2 input at V ' ref1-V
F1Above.Simultaneously, the 4th comparator 42 of OCT judging part 4 also relatively is judged as magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output more than predefined the 2nd OCT reference voltage value V ' ref2, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmin of rectification part 2 input at V ' ref2-V
F1Above.Therefore, frequency-converter device section starts overcurrent inhibition (OCS) function and overcurrent blockade (OCT) function and normally moves.
In T ' 1～T ' 2 intervals, the second comparator 32 of OCS judging part 3 and the 4th comparator 42 of OCT judging part 4 relatively are judged as magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output below predefined the 2nd OCS reference voltage value V ' ref1 and greater than predefined the 2nd OCT reference voltage value V ' ref2, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmin of rectification part 2 input at V ' ref1-V
F1Below and greater than V ' ref2-V
F1Therefore, frequency-converter device starts overcurrent and suppresses (OCS) function, and reducing work frequency and output voltage reduce output current automatically.
In T ' 2～T ' 3 intervals, the second comparator 32 of OCS judging part 3 and the 4th comparator 42 of OCT judging part 4 relatively are judged as magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output below predefined the 2nd OCS reference voltage value V ' ref1 and below predefined the 2nd OCT reference voltage value V ' ref2, that is, relatively be judged as magnitude of voltage to the voltage waveform Vmin of rectification part 2 input at V ' ref1-V
F1Below and Vref2-V
F1Below.Therefore, frequency-converter device starts overcurrent and blocks (OCT) function, stops output and realizes self-protection.
From the above, in the overcurrent sensing circuit of existing frequency-converter device, the output current of the frequency-converter device that will be detected by current sensor etc. is converted to voltage signal and obtains three-phase input voltage, and by 2 pairs of these three-phase input voltages of rectification part carry out diode rectification and respectively with predefined reference voltage value Vref1 and V ' ref1, Vref2 and V ' ref2 compare, and judge whether thus to start the OCS/OCT function.If be more than the predefined reference voltage value Vref1 from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output, perhaps the magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output is below the predefined reference voltage value V ' ref1, then starts the OCS function; If be more than the predefined reference voltage value Vref2 from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output, perhaps the magnitude of voltage Vanode from the common anode end Tanode of rectification part 2 output is below the predefined reference voltage value V ' ref1, then starts the OCT function.Start the OCS function, then the automatic reducing work frequency of frequency-converter device and output voltage reduce output current, at this moment, start the OCT function if current value further raises, and then frequency-converter device stops output and realizes self-protection.
Though such overcurrent inhibition method has the simple advantage of circuit, but use the operational amplifier of 4 costlinesses in order to consist of 4 comparators, thereby exist the manufacturing cost of circuit to uprise and the size that is used for consisting of the printed circuit board (PCB) (PCB) of overcurrent sensing circuit becomes large shortcoming.
Summary of the invention
The present invention proposes in order to address the above problem, and the object of the present invention is to provide a kind of low cost of manufacture and be used for to consist of the little overcurrent sensing circuit of the size of PCB of overcurrent sensing circuit and have the frequency-converter device of this overcurrent sensing circuit.
Overcurrent sensing circuit of the present invention that be used for to realize above-mentioned purpose is characterised in that, comprising: the voltage input part, and it is used for the input voltage that input is converted to the output current of the frequency-converter device that detects; Rectification part, it has for the diode row that consist of full-wave rectifying circuit, is used for the above-mentioned input voltage that receives from above-mentioned voltage input part is carried out rectification; Reciprocal transformation section, it is used for the voltage waveform of receiving from the common anode termination of above-mentioned rectification part is carried out reciprocal transformation; The magnitude of voltage selection portion, it optionally makes the little voltage waveform of magnitude of voltage pass through from the voltage waveform of the common cathode end of above-mentioned rectification part output with from the voltage waveform of above-mentioned reciprocal transformation section output; Overcurrent suppresses judging part, and it judges whether to start the overcurrent inhibit feature according to the magnitude of voltage that receives from above-mentioned magnitude of voltage selection portion; Overcurrent is blocked judging part, and it judges whether to start the overcurrent lock-out facility according to the magnitude of voltage that receives from above-mentioned magnitude of voltage selection portion.
Above-mentioned overcurrent sensing circuit is characterised in that, the scope of the magnitude of voltage of each phase of the above-mentioned input voltage that receives from above-mentioned voltage input part is 0～+ Vcc, and the voltage waveform of above-mentioned each phase is symmetrical take the Vcc/2 axle as benchmark.
Above-mentioned overcurrent sensing circuit is characterised in that, is applied with high voltage Vcc at the common anode end of above-mentioned rectification part.
Above-mentioned overcurrent sensing circuit is characterised in that, above-mentioned reciprocal transformation section be used for the voltage waveform reciprocal transformation that will receive from the common anode termination of above-mentioned rectification part for take the Vcc/2 axle as benchmark with the laterally zygomorphic waveform of this voltage waveform of receiving from the common anode termination of above-mentioned rectification part.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned reciprocal transformation section is made of the differential amplifier that comprises operational amplifier, the in-phase input end of this operational amplifier is applied with voltage vcc/2, between the common anode end of inverting input and above-mentioned rectification part, be connected with the first resistance, between output and the distolateral end of the anti-phase input of above-mentioned the first resistance, be connected with the second identical resistance of resistance value of resistance value and above-mentioned the first resistance.
In above-mentioned overcurrent sensing circuit, preferably, put on the voltage vcc of the in-phase input end of above-mentioned operational amplifier/2nd, obtain by electric resistance partial pressure.
In above-mentioned overcurrent sensing circuit, preferably, 2 diodes that the same degree that above-mentioned magnitude of voltage selection portion comprises the 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 the first operational amplifier, and the negative pole of each diode is connected and consists of the common cathode end of above-mentioned magnitude of voltage selection portion.
In above-mentioned overcurrent sensing circuit, preferably, be provided with compensating resistance at the common cathode end of above-mentioned rectification part, this compensating resistance is used for making the part current distributing 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 and comprises that overcurrent suppresses comparator, and this overcurrent suppresses the comparator reception from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output and suppress reference voltage value with predefined overcurrent to compare.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent suppresses judging part and judges relatively by above-mentioned overcurrent inhibition comparator whether from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output be that predefined overcurrent suppresses to judge whether thus to start the overcurrent inhibit feature more than the reference voltage value.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent is blocked judging part and is comprised overcurrent blockade comparator, and this overcurrent is blocked comparator reception from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output and blocked reference voltage value with predefined overcurrent and compares.
In above-mentioned overcurrent sensing circuit, preferably, above-mentioned overcurrent is blocked judging part and is judged relatively by above-mentioned overcurrent blockade comparator whether from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output be that predefined overcurrent is blocked more than the reference voltage value, judges whether thus to start the overcurrent lock-out facility.
Be used for realizing that the frequency-converter device of the present invention of above-mentioned purpose is characterised in that to have above-mentioned overcurrent sensing circuit.
If employing the present invention then compares with the overcurrent sensing circuit of existing frequency-converter device, can be less with the operational amplifier of a costliness, so not only can reduce manufacturing cost, but also can dwindle the size for the PCB that consists of overcurrent sensing circuit.
Description of drawings
Fig. 1 shows the figure of the overcurrent sensing circuit of existing frequency-converter device.
Fig. 2 is the oscillogram from the alternating voltage of each phase of the three-phase input voltage of the voltage input part input of the overcurrent sensing circuit of frequency-converter device.
Fig. 3 is the oscillogram be used to the three-phase input voltage of the action of the overcurrent sensing circuit that existing frequency-converter device is described.
Fig. 4 shows the figure of the overcurrent sensing circuit of frequency-converter device of the present invention.
Fig. 5 is the oscillogram be used to the reciprocal transformation result of the reciprocal transformation section of the overcurrent sensing circuit that frequency-converter device of the present invention is described.
Fig. 6 is the oscillogram be used to the action of the overcurrent sensing circuit that frequency-converter device of the present invention is described.
The explanation of Reference numeral
1 voltage input part
2 rectification part
3 OCS judging parts
31 first comparators, 32 second comparators
4 OCT judging parts
41 the 3rd comparators 42 the 4th comparator
30 reciprocal transformation sections
301 operational amplifier R1 the first resistance R, 2 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 elaborated.
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 used for the input 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 for the diode row that consist of three-phase full wave rectifier circuit, is used for the three-phase input voltage that receives from overvoltage input part 1 is carried out rectification; Reciprocal transformation section 30, it is used for the voltage waveform that the common anode end Tanode that the diode from rectification part 2 is listed as receives is carried out reciprocal transformation; Magnitude of voltage selection portion 50, it optionally makes the little voltage waveform of magnitude of voltage pass through at the voltage waveform of the common cathode end Tcathode output that the diode from rectification part 2 is listed as and from the voltage waveform that reciprocal transformation section 30 exports; OCS judging part 60, it judges whether to start overcurrent according to the magnitude of voltage that receives from magnitude of voltage selection portion 50 and suppresses (OCS) function; OCT judging part 70, it judges whether to start overcurrent according to the magnitude of voltage that receives from magnitude of voltage selection portion 50 and blocks (OCT) function.
Comparison diagram 4 and Fig. 1 as can be 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 are identical.Therefore, above all the elements about the voltage input part 1 in the overcurrent sensing circuit of existing frequency-converter device and rectification part 2 of putting down in writing, obviously can be applicable to respectively voltage input part 1 and rectification part 2 in the overcurrent sensing circuit of frequency-converter device of the present invention, so no longer repeat explanation at this.
In reciprocal transformation section 30, can realize being applied to voltage vcc on the in-phase input end/2 by electric resistance partial pressure.Also have, when identical (that is, in the time of R1=R2), according to the known relation between each parameter of differential amplifier, can being illustrated from the magnitude of voltage Vo of the output output of operational amplifier 301 by following formula (9) of resistance value of the first resistance R 1 and the second resistance R 2.
Vo=（R1+R2）/R1×Vcc/2-R2/R1×Vanode=Vcc-Vanode（9）
To the above-mentioned formula of above formula (9) substitution (2), (3) and (4), then can derive following formula (10).
Vo=Vcc-Vmin-V
F1=Vmax-V
F1=Vcathode（10）
Reach (5) as can be known from above formula (10), reciprocal transformation section 30 has following function: the voltage waveform Vanode reciprocal transformation that the common anode end Tanode that will be listed as from the diode of rectification part 2 receives is take the Vcc/2 axle as benchmark and the laterally zygomorphic output waveform Vo(=Vcathode of this voltage waveform Vanode).
And, if formula (2)～(3) are also taken into account, can think also that then reciprocal transformation section 30 has following function: alternating voltage Vu, Vv, the Vw of each phase that will be arranged in the three-phase input voltage of arbitrary enough little time interval (perhaps between phase region) has the voltage waveform Vmin of alternating voltage of the phase of minimum voltage value, reciprocal transformation for take the Vcc/2 axle as benchmark and the laterally zygomorphic voltage waveform of this voltage waveform Vmin be voltage waveform Vmax(=Vcc-Vmin).
Fig. 5 is the oscillogram be used to the reciprocal transformation result of the reciprocal transformation section 30 of the overcurrent sensing circuit that frequency-converter device of the present invention is described, it is the state of voltage waveform Vcc-Vmin that the voltage waveform Vmin of alternating voltage that alternating voltage Vu, Vv, the Vw that shows each phase of the three-phase input voltage that is arranged in arbitrary enough little time interval (perhaps between phase region) has a phase of minimum voltage value is reversed transformation component 30 reciprocal transformations.In addition, for convenience of explanation, also show simultaneously not the voltage waveform Vmax via reciprocal transformation section 30.
Also have, reference is about the explanation of 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 the Vw is 120 degree, the alternating voltage Vu of each phase, Vv, sinusoidal wave period and the amplitude of Vw are identical, even so alternating voltage Vu of each phase, Vv, the alternating voltage of the arbitrary phase among the Vw (for example, the alternating voltage that U phase voltage Vu) also can represent other phases (for example, V phase voltage Vv or W phase voltage Vw) behavior, thereby in Fig. 5, only show the waveform portion of U phase voltage Vu.
Yet actual waveform is not desirable sine wave, but comprises the sine wave (the heavy line part among Fig. 5) of high-frequency harmonic composition.And, except the waveform portion of illustrated U phase voltage Vu, also exist with the waveform portion of this U phase voltage Vu to have respectively the identical V phase voltage Vv of the phase differences of 120 degree and cycle and amplitude and the waveform portion of W phase voltage Vw, thus the waveform of reality be each phase of three-phase input voltage alternating voltage Vu, Vv, Vw separately voltage waveform Vmax and alternating voltage Vu, Vv, the Vw voltage waveform Vmin separately of each phase be reversed the waveform that each the voltage waveform Vcc-Vmin after transformation component 30 reciprocal transformations alternates and intersects to form.Fig. 6 shows such waveform.
Fig. 6 is the oscillogram be used to the action of the overcurrent sensing circuit that frequency-converter device of the present invention is described, alternating voltage Vu, Vv, the Vw that shows simultaneously each phase of three-phase input voltage separately voltage waveform Vmax and alternating voltage Vu, Vv, the Vw voltage waveform Vmin separately of each phase be reversed each the voltage waveform Vcc-Vmin after transformation component 30 reciprocal transformations.As shown in the drawing, alternating voltage Vu, the Vv of each phase, Vw voltage waveform Vmax separately is about V at its magnitude of voltage " the voltage waveform Vcc-Vmin that is reversed after transformation component 30 reciprocal transformations of the voltage waveform Vmin of the position of cross and other adjacent phases intersects.In other words, alternating voltage Vu, the Vv of each phase of three-phase input voltage, Vw separately voltage waveform Vmax and alternating voltage Vu, Vv, the Vw voltage waveform Vmin separately of each phase be reversed each the voltage waveform Vcc-Vmin after transformation component 30 reciprocal transformations, be about V take its magnitude of voltage " each crossover node of cross alternately has maximum voltage value (the heavy line part among Fig. 6) as benchmark.That is, alternately has maximum voltage value from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output with from the magnitude of voltage Vo of the output output of reciprocal transformation section 30.
Return to Fig. 4, magnitude of voltage selection portion 50 comprises forward voltage drop tube V
F22 high diodes of same degree of value, 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 reciprocal transformation section 30, and the negative pole of each diode is connected and consists of the common cathode end of magnitude of voltage selection portion 50.
Conducting principle as the diode of rectification part 2 row, magnitude of voltage selection portion 50 only makes the diode current flow that is applied with the specific voltage waveform, this specific voltage waveform refers to, from the magnitude of voltage Vcathode of the common cathode end Tcathode output of rectification part 2 and from the magnitude of voltage Vo of the output output of reciprocal transformation section 30 the large voltage waveform of magnitude of voltage.That is, from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output with from the magnitude of voltage Vo of the output output of reciprocal transformation section 30, magnitude of voltage selection portion 50 optionally only makes the large voltage waveform of magnitude of voltage pass through.
In addition, from the output voltage V cathode of the common cathode end Tcathode of rectification part 2 output during by a diode the magnitude of voltage selection portion 50, the magnitude of voltage V that can descend
F2, cause this magnitude of voltage to become Vcathode-V
F2=Vmax-V
F1-V
F2And, from the output voltage V o of the output of reciprocal transformation section 30 output during by another diode the 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
Hence one can see that, and another diode magnitude of voltage afterwards that the voltage waveform Vmin that alternating voltage Vu, the Vv of each phase, the voltage waveform Vmax of Vw have passed through alternating voltage Vu, Vv, the Vw of magnitude of voltage and each phase after the diode of magnitude of voltage selection portion 50 has passed through reciprocal transformation section 30 and magnitude of voltage selection portion 50 becomes in full accord.Therefore; suppress the inhibition grade of (OCS) function and the consistency that overcurrent is blocked the blockade grade of (OCT) function in order to ensure the overcurrent based on the magnitude of voltage after 2 diodes that passed through respectively magnitude of voltage selection portion 50; preferably, should select maximum voltage value in the magnitude of voltage of these 2 parts to compare to judge to process.
For this reason, utilize magnitude of voltage selection portion 50, select maximum voltage value to form the selection voltage waveform among the voltage waveform Vo after the voltage waveform Vmin of each mutually alternating voltage Vu, Vv, the Vw of the voltage waveform Vmax of alternating voltage Vu, the Vv of each phase of three-phase input voltage, Vw and three-phase input voltage is reversed transformation component 30 reciprocal transformations, 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 to be illustrated by following formula (11).
Vselect=Vmax-V
F1-V
F2（11）
Also have, because the forward voltage drop tube V of each diode of magnitude of voltage selection portion 50
F2Depend on the current value that flows through this diode, so for the current value of 2 diodes making overvoltage value selection portion 50 consistent, preferably at the common cathode end Tcathode of rectification part 2 compensating resistance 40 that is made of the 3rd resistance R 3 is set, this compensating resistance 40 is used for making the part current distributing to the consistency of ground wire with the forward voltage drop tube of guaranteeing 2 diodes.The 3rd resistance R 3 is elected variable resistance as.
Also have, OCT judging part 70 comprises the OCT comparator 701 that is made of operational amplifier, is used for reception and compares from the magnitude of voltage Vselect of the common cathode end output of magnitude of voltage selection portion 50 and with predefined OCT reference voltage value Vref4.At this moment, OCT judging part 70 judges relatively by OCT comparator 701 whether the magnitude of voltage Vselect that exports from the common cathode end of magnitude of voltage selection portion 50 is more than the predefined OCT reference voltage value Vref4, that is, judge relatively whether to the voltage waveform Vmax magnitude of voltage partly of rectification part 2 inputs be Vref4+V
F1+ V
F2Above or whether be Vref4-V to the magnitude of voltage of the voltage waveform Vmin part of rectification part 2 input
F1-V
F2Below (with reference to Fig. 6), judge whether thus to start overcurrent and block (OCT) function.
At this moment, 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.
At first, alternating voltage Vu, Vv, the Vw with each phase of three-phase input voltage is applied to rectification part 2.
As shown in Figure 2, the alternating voltage of a certain phase has the time interval of maximum voltage value (perhaps between phase region among alternating voltage Vu, the Vv of each phase, the Vw; The interval between crossover node b and the c for example), the alternating voltage that is overlapped in another phase mutually adjacent with this has the time interval of minimum voltage value (perhaps between phase region; The interval between the interval between crossover node a ' and the b ' or crossover node b ' and the c ' for example).In other words, with regard to arbitrary enough little time interval (perhaps between phase region), when the alternating voltage of a certain phase had maximum voltage value among alternating voltage Vu, the Vv of each phase, the Vw, the alternating voltage of another phase mutually adjacent with this had the minimum voltage value.
In the time interval between crossover node a and a ' (perhaps between phase region), in alternating voltage Vu, the Vv of each phase that puts on rectification part 2, Vw, the waveform Vmax of U phase voltage Vu has maximum voltage value, at this moment, only making the upside diode current flow that is connected with U phase voltage Vu, is Vcathode=Vmax-V from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output
F1Simultaneously, in alternating voltage Vu, the Vv of each phase of the three-phase input voltage that puts on rectification part 2, Vw, the waveform Vmin of V phase voltage Vv has the minimum voltage value, at this moment, only making the downside diode current flow that is connected with V phase voltage Vv, is Vmin+V from the magnitude of voltage Vanode of the common anode end Tanode of rectification part 2 output
F1
Be directly inputted into a diode of magnitude of voltage selection portion 50 from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output.
Input to reciprocal transformation section 30 from the magnitude of voltage Vanode of the common anode end Tanode of rectification part 2 output, and the output waveform Vo(=Vcc-Vmin-V after the output output reciprocal transformation of this reciprocal transformation section 30
F1=Vmax-V
F1) (with reference to the voltage waveform Vcc-Vmin among Fig. 5).
Voltage waveform Vo(=Vcc-Vmin-V from the output of the output of reciprocal transformation section 30
F1) input to another diode of magnitude of voltage selection portion 50.
Magnitude of voltage selection portion 50 is from the magnitude of voltage Vcathode of the common cathode end Tcathode of rectification part 2 output with select the large voltage waveform of magnitude of voltage to form from the magnitude of voltage Vo of the output output of reciprocal transformation section 30 and select 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 that exports from the common cathode end of magnitude of voltage selection portion 50 inputs to OCS judging part 60.OCS judging part 60 judges relatively whether magnitude of voltage Vselect is more than the predefined OCS reference voltage value Vref3,, judges relatively whether to the voltage waveform Vmax magnitude of voltage partly of rectification part 2 inputs be Vref3+V that is
F1+ V
F2Above or whether be Vref3-V to the magnitude of voltage of the voltage waveform Vmin part of rectification part 2 input
F1-V
F2Below (with reference to Fig. 6).
If magnitude of voltage Vselect is less than predefined OCS reference voltage value Vref3, then frequency-converter device does not start overcurrent inhibition (OCS) function and overcurrent blockade (OCT) function and normally moves.
If magnitude of voltage Vselect is more than the predefined OCS reference voltage value Vref3, then frequency-converter device starts overcurrent inhibition (OCS) function, and reducing work frequency and output voltage reduce output current automatically.
In addition.The magnitude of voltage Vselect that exports from the common cathode end of magnitude of voltage selection portion 50 also inputs to OCT judging part 70.OCT judging part 70 judges relatively whether magnitude of voltage Vselect is more than the predefined OCT reference voltage value Vref4,, judges relatively whether to the voltage waveform Vmax magnitude of voltage partly of rectification part 2 inputs be Vref4+V that is
F1+ V
F2Above or whether be Vref4-V to the magnitude of voltage of the voltage waveform Vmin part of rectification part 2 input
F1-V
F2Below (with reference to Fig. 6).
If magnitude of voltage Vselect is less than predefined OCT reference voltage value Vref4, then frequency-converter device judges whether to start overcurrent inhibition (OCS) function according to the comparison judged result of OCS judging part 60.
If magnitude of voltage Vselect is more than the predefined OCT reference voltage value Vref4, then frequency-converter device starts overcurrent blockade (OCT) function, stops output and realizes self-protection.
Between crossover node a ' and the b, between b and the b ', between b ' and the c, between c and the c ', between c ' and the d, in the equal time interval (perhaps between phase region), overcurrent sensing circuit of the present invention also with and aforesaid crossover node a and a ' between time interval (perhaps between phase region) in the similar mode of method of operating move, so no longer repeat explanation at this.
Above with reference to accompanying drawing, be illustrated for overcurrent sensing circuit of the present invention and frequency-converter device with this overcurrent sensing circuit, but these contents are most preferred embodiments of the present invention, can not be considered as limitation of the invention.
For example, in above embodiment, although for example understand the overcurrent sensing circuit that is used for the three phase variable frequency apparatus, but overcurrent sensing circuit of the present invention also goes for the frequency-converter device of three above phases, for this reason, as long as rectification part 2 is constituted full-wave rectifying circuit corresponding to the phase more than three.
Therefore, for the general technical staff of the technical field of the invention, the various deformation of implementing in the scope of the category that does not break away from technological thought of the present invention and imitation obviously all belong to protection scope of the present invention.
Claims (15)
1. the overcurrent sensing circuit of a frequency-converter device is characterized in that, comprising:
The voltage input part, it is used for the input voltage that input is converted to the output current of the frequency-converter device that detects;
Rectification part, it has for the diode row that consist of full-wave rectifying circuit, is used for the above-mentioned input voltage that receives from above-mentioned voltage input part is carried out rectification;
Reciprocal transformation section, it is used for the voltage waveform of receiving from the common anode termination of above-mentioned rectification part is carried out reciprocal transformation;
The magnitude of voltage selection portion, it optionally makes the little voltage waveform of magnitude of voltage pass through from the voltage waveform of the common cathode end of above-mentioned rectification part output with from the voltage waveform of above-mentioned reciprocal transformation section output;
Overcurrent suppresses judging part, and it judges whether to start the overcurrent inhibit feature according to the magnitude of voltage that receives from above-mentioned magnitude of voltage selection portion;
Overcurrent is blocked judging part, and it judges whether to start the overcurrent lock-out facility according to the magnitude of voltage that receives 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 that receives from above-mentioned voltage input part is 0～+ Vcc, and the voltage waveform of above-mentioned each phase is symmetrical take the Vcc/2 axle as benchmark.
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 reciprocal transformation section be used for the voltage waveform reciprocal transformation that will receive from the common anode termination of above-mentioned rectification part for take the Vcc/2 axle as benchmark with the laterally zygomorphic waveform of this voltage waveform of receiving from the common anode termination of above-mentioned rectification part.
5. the overcurrent sensing circuit of frequency-converter device according to claim 3, it is characterized in that, above-mentioned reciprocal transformation section is made of the differential amplifier that comprises operational amplifier, the in-phase input end of this operational amplifier is applied with voltage vcc/2, between the common anode end of inverting input and above-mentioned rectification part, be connected with the first resistance, between output and the distolateral end of the anti-phase input of above-mentioned the first resistance, be connected with the second identical resistance of resistance value of resistance value and above-mentioned the first resistance.
6. the overcurrent sensing circuit of frequency-converter device according to claim 5 is characterized in that, puts on the voltage vcc of the in-phase input end of above-mentioned operational amplifier/2nd, obtains by electric resistance partial pressure.
7. the overcurrent sensing circuit of each the described frequency-converter device in 4 according to claim 1 is characterized in that 2 diodes that the same degree that above-mentioned magnitude of voltage selection portion comprises the forward voltage drop tube value is high.
8. according to claim 5 or the overcurrent sensing circuit of 6 described frequency-converter devices, it is characterized in that 2 diodes that the same degree that above-mentioned magnitude of voltage selection portion comprises the 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 above-mentioned the first operational amplifier, and the negative pole of each diode is connected and consists of the common cathode end of above-mentioned magnitude of voltage selection portion.
10. the overcurrent sensing circuit of each described frequency-converter device in 9 according to claim 7, it is characterized in that, common cathode end in above-mentioned rectification part is provided with compensating resistance, this compensating resistance is used for making the part current distributing to ground wire, guarantees the consistency of the forward voltage drop tube value of above-mentioned 2 diodes.
11. the overcurrent sensing circuit of each the described frequency-converter device in 6 according to claim 1, it is characterized in that, above-mentioned overcurrent suppresses judging part and comprises that overcurrent suppresses comparator, and this overcurrent suppresses the comparator reception from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output and suppress reference voltage value with predefined overcurrent to compare.
12. the overcurrent sensing circuit of frequency-converter device according to claim 11, it is characterized in that, above-mentioned overcurrent suppresses judging part and judges relatively by above-mentioned overcurrent inhibition comparator whether from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output be that predefined overcurrent suppresses to judge whether thus to start the overcurrent inhibit feature more than the reference voltage value.
13. the overcurrent sensing circuit of each the described frequency-converter device in 6 according to claim 1, it is characterized in that, above-mentioned overcurrent is blocked judging part and is comprised overcurrent blockade comparator, and this overcurrent is blocked comparator reception from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output and blocked reference voltage value with predefined overcurrent and compares.
14. the overcurrent sensing circuit of frequency-converter device according to claim 13, it is characterized in that, above-mentioned overcurrent is blocked judging part and is judged relatively by above-mentioned overcurrent blockade comparator whether from the magnitude of voltage of above-mentioned magnitude of voltage selection portion output be that predefined overcurrent is blocked more than the reference voltage value, judges whether thus to start the overcurrent lock-out facility.
15. a frequency-converter device is characterized in that, has each the described overcurrent sensing circuit in the claim 1 to 14.
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| US20090174978A1 (en) * | 2008-01-08 | 2009-07-09 | Sanken Electric Co., Ltd. | Switching power supply device |
| 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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| 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 |
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Address after: LS Le Xing Lu Industrial Park National hi tech Industrial Development Zone of Wuxi City, Jiangsu province 214028 Patentee after: Lexing electric (Wuxi) Co.,Ltd. Address before: LS Le Xing Lu Industrial Park National hi tech Industrial Development Zone of Wuxi City, Jiangsu province 214028 Patentee before: LS INDUSTRIAL SYSTEMS Co.,Ltd. |