CN101615848A - A kind of variable frequency soft starter - Google Patents
A kind of variable frequency soft starter Download PDFInfo
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- CN101615848A CN101615848A CN200810039437A CN200810039437A CN101615848A CN 101615848 A CN101615848 A CN 101615848A CN 200810039437 A CN200810039437 A CN 200810039437A CN 200810039437 A CN200810039437 A CN 200810039437A CN 101615848 A CN101615848 A CN 101615848A
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Abstract
The invention discloses a kind of variable frequency soft starter, have: as three groups of antiparallel controllable silicons of device for power switching and the drive circuits of controllable silicon being controlled according to the instruction of single chip circuit, follow the tracks of input voltage phase voltage sampling circuit, follow the tracks of the current sampling circuit of the output current of variable frequency soft start device, as the single-chip microcomputer of control core and the instruction input circuit that single chip circuit is controlled; Also has back-emf sensing circuit.So intelligently the voltage that is input to motor according to the Frequency Converter Control principle, carry out voltage magnitude and FREQUENCY CONTROL, not only pressure regulation but also frequency modulation, thereby reach with smaller electric current starting three-phase AC asynchronous motor.
Description
Technical field
The present invention relates to a kind of soft initiator, be specially a kind of soft initiator that can change frequency, belong to electric field.
Background technology
Soft driver is used widely in the motor starting of all trades and professions, the prior art level is to adopt controllable silicon as power device, the phase place that adopts single-chip microcomputer to follow the tracks of input voltage is made the pressure regulation Current limited Control, use contactor the controllable silicon bypass after starting finishes, three-phase AC asynchronous motor drops into operation of power networks.Existing soft starter starting current is generally (starting nominal load) and reaches 4 to 5 times of rated current.Starting current is big, causes power source trip sometimes, and speed and moment of torsion are uncontrollable, therefore some producer has to adopt frequency converter to start three-phase AC asynchronous motor, and electric current generally is no more than 15 times of rated value during the frequency converter starting, and is little more a lot of than soft starter.But the cost of frequency converter is somewhat expensive, and reliability is more weaker than soft starter.
Summary of the invention
Goal of the invention of the present invention is for a kind of variable frequency soft starter is provided, and to solve the existing big problem of soft initiator starting current, makes its performance with frequency converter, and low cost.
Purpose of the present invention can be achieved through the following technical solutions.
A kind of variable frequency soft starter has: as three groups of antiparallel controllable silicons of device for power switching and the drive circuits of controllable silicon being controlled according to the instruction of single chip circuit, follow the tracks of input voltage phase voltage sampling circuit, follow the tracks of the current sampling circuit of the output current of variable frequency soft start device, as the single-chip microcomputer of control core and the instruction input circuit that single chip circuit is controlled; Also has back-emf sensing circuit.
Described back-emf sensing circuit is by one group of independent current source VDD, three resistance (two R
1With a R
2) and the comparator composition; R
1Any two-phase among one termination three phase mains U, V, the W, the other end meets R respectively
2Two ends and insert the positive and negative level of comparator; Comparator is electrically connected and ground connection with independent current source VDD respectively; Behind three electric resistance partial pressures in resistance R
2On obtain little AC signal, obtain the square wave switching signal behind the input comparator.
Described voltage sampling circuit is followed the tracks of the phase place of input voltage, back-emf sensing circuit is followed the tracks of the phase place of three-phase AC asynchronous motor back-emf, current sampling circuit is followed the tracks of the output current of variable frequency soft start device, drive circuit is according to the instruction of single chip circuit controllable silicon to be controlled, the instruction input circuit is controlled single chip circuit, so intelligently input voltage according to the Frequency Converter Control principle, carry out voltage magnitude and a grade variable frequency control arranged, to reach the purpose of not only pressure regulation but also frequency modulation.
Described have an optional f/N of grade variable frequency control, and wherein f is a mains frequency, and Chinese electrical network is 50Hz, and N is the 1.2.3......50 natural integer.
Pressure regulation of the present invention is followed the tracks of phase place according to the wave head number that this frequency comprised and is carried out AC chopping control, according to frequency converter voltage/frequency=constant, controls in real time.
By the variable frequency soft starter that technical solution of the present invention designs, combine the advantage of existing soft start and frequency converter, created a kind of cheap, starting current is little, reliability is high, variable frequency soft start device that again can frequency modulation.
Description of drawings
Fig. 1 is a circuit module figure of the present invention;
Fig. 2 is the circuit diagram of back-emf sensing circuit among the present invention;
Fig. 3 is the schematic diagram of variable frequency control example of the present invention, and among the figure: curve 1 is the envelope of the output voltage frequency of needs, and curve 2 is the waveform of power supply input.
Fig. 4 is the schematic diagram of pressure regulation copped wave example of the present invention; Among the figure: a, b and c are respectively the three-phase voltage oscillogram; D is the waveform behind the chopper control.
Embodiment
Further specify technical characterstic of the present invention below in conjunction with accompanying drawing and specific embodiment.
The circuit module figure of variable frequency soft starter as shown in Figure 1, power switch A is by three groups of antiparallel controllable silicon rate of doing work switching devices, single chip circuit F is as the control core, voltage sampling circuit B follows the tracks of the phase place of input voltage, back-emf sensing circuit C follows the tracks of the phase place of three-phase AC asynchronous motor back-emf, current sampling circuit D follows the tracks of the output current of variable frequency soft start device, drive circuit G controls controllable silicon according to the instruction of single chip circuit F, instruction input circuit E controls single chip circuit F, so intelligently input voltage according to the Frequency Converter Control principle, carry out voltage magnitude and FREQUENCY CONTROL, to reach the purpose of not only pressure regulation but also frequency modulation, except that back-emf sensing circuit C was different with existing soft start, other circuit were basic identical in the embodiments of the invention.
Back-emf sensing circuit as shown in Figure 2; Described back-emf sensing circuit is by one group of independent current source VDD, three resistance (two R
1With a R
2) and comparator A composition; R
1Any two-phase among one termination three phase mains U, V, the W, the other end meets R respectively
2Two ends and insert the positive and negative level of comparator; Comparator A is electrically connected and ground connection with independent current source VDD respectively; Behind three electric resistance partial pressures in resistance R
2On obtain little AC signal, obtain the square wave switching signal behind the input comparator A.
Illustrate the method for chopper control of the present invention and frequency conversion below
Variable frequency control example schematic is as shown in Figure 3 selected the voltage wave head according to the starting frequency envelope, can carry out variable frequency control easily.Curve 1 is the envelope of the output voltage frequency of needs, the waveform of curve 2 power supplys input.
The pressure regulation chopping method as shown in Figure 4, according to the principle of voltage conducting in twos, setting the A phase voltage is UA-UC, the B phase voltage is UB-UA, the C phase voltage is UC-UB.
By the foregoing description and example schematic as seen: what variable frequency soft start device of the present invention can be identical with frequency converter starts three-phase AC asynchronous motor with less current.
Claims (5)
1, a kind of variable frequency soft starter has: as three groups of antiparallel controllable silicons of device for power switching and the drive circuits of controllable silicon being controlled according to the instruction of single chip circuit, follow the tracks of input voltage phase voltage sampling circuit, follow the tracks of the current sampling circuit of the output current of variable frequency soft start device, as the single-chip microcomputer of control core and the instruction input circuit that single chip circuit is controlled; It is characterized in that: also have back-emf sensing circuit.
2, a kind of variable frequency soft starter according to claim 1 is characterized in that: described back-emf sensing circuit, form by one group of independent current source VDD, three resistance and comparator; Behind three electric resistance partial pressures in resistance R
2On obtain little AC signal, obtain the square wave switching signal behind the input comparator.
3, a kind of variable frequency soft starter according to claim 1 is characterized in that: have pressure regulation and a grade variable frequency control is arranged.
4, a kind of variable frequency soft starter according to claim 3 is characterized in that: described have an optional f/N of grade variable frequency control, and wherein f is a mains frequency, and Chinese electrical network is 50Hz, and N is the 1.2.3......50 natural integer.
5, a kind of variable frequency soft starter according to claim 3 is characterized in that: described pressure regulation is followed the tracks of phase place according to the wave head number that this frequency comprised and is carried out AC chopping control, according to frequency converter voltage/frequency=constant, controls in real time.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200810039437A CN101615848A (en) | 2008-06-24 | 2008-06-24 | A kind of variable frequency soft starter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN200810039437A CN101615848A (en) | 2008-06-24 | 2008-06-24 | A kind of variable frequency soft starter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN101615848A true CN101615848A (en) | 2009-12-30 |
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| CN200810039437A Pending CN101615848A (en) | 2008-06-24 | 2008-06-24 | A kind of variable frequency soft starter |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102097983A (en) * | 2011-02-12 | 2011-06-15 | 鞍山市权晟电子电力有限公司 | Network type all-digital motor soft starter |
| CN102170719A (en) * | 2011-03-10 | 2011-08-31 | 清华大学 | Induction heating power supply phase tracking system with switch device negative voltage limiting function |
| CN102904492A (en) * | 2011-07-28 | 2013-01-30 | 万洲电气股份有限公司 | Graded frequency conversion stepless voltage regulating soft starting device based on non-speed sensor |
| CN105991080A (en) * | 2015-02-26 | 2016-10-05 | 伊顿公司 | Device for connection of motor and power grid |
| CN108322034A (en) * | 2018-01-26 | 2018-07-24 | 郑州云海信息技术有限公司 | A kind of soft starting device and method of Switching Power Supply |
-
2008
- 2008-06-24 CN CN200810039437A patent/CN101615848A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102097983A (en) * | 2011-02-12 | 2011-06-15 | 鞍山市权晟电子电力有限公司 | Network type all-digital motor soft starter |
| CN102170719A (en) * | 2011-03-10 | 2011-08-31 | 清华大学 | Induction heating power supply phase tracking system with switch device negative voltage limiting function |
| CN102904492A (en) * | 2011-07-28 | 2013-01-30 | 万洲电气股份有限公司 | Graded frequency conversion stepless voltage regulating soft starting device based on non-speed sensor |
| CN105991080A (en) * | 2015-02-26 | 2016-10-05 | 伊顿公司 | Device for connection of motor and power grid |
| CN105991080B (en) * | 2015-02-26 | 2021-09-10 | 伊顿智能动力有限公司 | Connecting device for motor and power supply network |
| CN108322034A (en) * | 2018-01-26 | 2018-07-24 | 郑州云海信息技术有限公司 | A kind of soft starting device and method of Switching Power Supply |
| CN108322034B (en) * | 2018-01-26 | 2020-10-20 | 苏州浪潮智能科技有限公司 | Soft start device and method for switching power supply |
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Open date: 20091230 |