CN212543681U - Independent double-bridge arm variable frequency soft starter - Google Patents
Independent double-bridge arm variable frequency soft starter Download PDFInfo
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- CN212543681U CN212543681U CN202021234669.4U CN202021234669U CN212543681U CN 212543681 U CN212543681 U CN 212543681U CN 202021234669 U CN202021234669 U CN 202021234669U CN 212543681 U CN212543681 U CN 212543681U
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Abstract
The utility model discloses an independent double-bridge arm frequency conversion type soft starter, which comprises a rectification circuit, an inverter circuit, a capacitor C, a bidirectional thyristor and a switch S and a switch K; the wire outlet end of the rectification circuit is connected with the wire inlet end of the inverter circuit through a direct current bus; two-phase inversion output of the three-phase alternating current respectively corresponds to a U phase and a V phase of the motor, and the middle point of the capacitor C corresponds to a W phase of the motor; two capacitors C are connected in series and then connected in parallel at the end of a direct current bus, and the midpoint of the two capacitors C is used as a reference point and is connected with the phase A of the power supply and the phase W of the variable frequency output through the bidirectional thyristor. The independent double-bridge arm variable-frequency soft starter reduces the difference between the frequency converter and the soft starter, reduces power switching devices in the traditional alternating current-direct current alternating frequency circuit, realizes high-efficiency soft starting of the motor by adopting the independent double-bridge arm variable-frequency soft starter, and has the advantages of high reliability, small volume and low cost.
Description
Technical Field
The utility model belongs to the technical field of AC-DC-AC frequency converter, in particular to three-phase asynchronous motor's independent double bridge arm frequency conversion formula soft starter.
Background
For a power frequency running motor with medium and high power and without speed regulation requirements, because the current for direct starting is large, a soft starter is usually adopted for starting so as to prevent the impact of the motor on a power grid. The widely used silicon controlled voltage regulating type soft starter has the advantages of low cost, flexible control, controllable starting current and the like, and is one of the soft starters commonly used at present. However, the voltage-regulating and speed-regulating principle is adopted, so that the defect that the on-load starting cannot be realized due to small starting torque exists in principle, and the AC-DC-AC frequency conversion technology can realize rated torque starting and limit the current within the rated value, but the following defects exist:
the rectifier and inverter circuits adopt more switching devices, so that the size of the frequency converter is increased, the cost is increased, and the frequency converter is usually more than several times of the price of the same soft starter or even more. When one frequency converter is used for starting a plurality of motors, the bypass switching circuit is complex and the control requirement is increased, thereby reducing the reliability and the economical efficiency.
SUMMERY OF THE UTILITY MODEL
When being used for soft start for solving traditional AC DC AC converter, the circuit power switch device is more and be difficult to the bypass and switch the scheduling problem, the utility model provides an independent double bridge arm frequency conversion type soft starter adopts power switch device quantity to save the third than traditional inverter circuit, has reduced the volume of converter, and the cost is reduced increases switching circuit and realizes the soft start of multimachine, and the control method goes up earlier the frequency conversion after the pressure regulating and has realized the control of the high-efficient starting torque of inverter circuit and low starting current.
The utility model discloses a realize through following technical scheme:
an independent double-bridge arm variable frequency soft starter comprises two rectification inversion units, wherein the two rectification inversion units are respectively connected with two phases of a power supply and a load, each rectification inversion unit is connected with a change-over switch S in parallel, and a reference phase of the power supply is directly connected with the other phase of the load;
the rectification inversion unit comprises a rectification circuit, a filter circuit, an inversion circuit, a bidirectional thyristor T and a switch K;
the input end of the rectifying circuit is connected with one end of the power supply, the output end of the rectifying circuit is connected with the filter circuit, the output end of the filter circuit is connected with the inverter circuit, and the output end of the inverter circuit is connected with one end of the load through a switch K;
the midpoint of the filter circuit is connected with the reference of a power supply through a bidirectional thyristor T and a switch S and is used for fixing the potential of a reference phase, and the bidirectional thyristor T receives a control signal;
and the PWM control signal input by the rectification inversion unit has a mutual difference of two-phase modulation waves of 60 degrees and a mutual difference of two-phase line voltages output by inversion of 60 degrees.
Preferably, the rectifier circuit comprises two independent double half-wave rectifier circuits.
Preferably, the double half-wave rectification circuit comprises a diode D1 and a diode D2, and the filter circuit comprises a capacitor C1 and a capacitor C2;
the cathode of the diode D1 is connected with one end of a capacitor C1, the other end of the capacitor C1 is connected with one end of a capacitor C2, the other end of the capacitor C2 is connected with the anode of a diode D2, the cathode of a diode D2 is connected with the anode of a diode D1, the connection point of the cathode of the diode D2 and the anode of a diode D1 is connected with a power supply, and the midpoint E1 of the capacitor C1 and the capacitor C2 is connected with the reference of the power supply.
Preferably, the capacitance C1 and the capacitance C2 have the same capacitance.
Preferably, the inverter circuit comprises a switching tube Q1, a switching tube Q2, a diode D5 and a diode D6;
the emitter of the switching tube Q1 is connected with the collector of the switching tube Q2, meanwhile, the connection point of the switching tube Q1 is connected with a load through a switch K, the collector of the switching tube Q1 is connected with one end of the filter circuit, and the two ends of the D5 of the diode are connected with the emitter and the collector of the switching tube Q1;
the emitter of the switching tube Q2 is connected with the other end of the filter circuit, and the two ends of the D6 of the diode are connected with the emitter and the collector of the switching tube Q2;
and the gates of the switching tube Q1 and the switching tube Q2 are connected with the DSP controller and used for receiving control signals.
Preferably, the switch K is an electronic switch or a mechanical switch.
Preferably, the input end of one of the rectification inverter units is connected with the power supply B, and the output end of the one of the rectification inverter units is connected with the load U; the input end of the other rectification inversion unit is connected with the C of the power supply, the output end of the other rectification inversion unit is connected with the V of the load, and the A phase of the power supply is connected with the W of the load.
Compared with the prior art, the utility model discloses following profitable technological effect has:
the utility model provides a pair of independent double bridge arm frequency conversion formula soft starter realizes pressure regulating, frequency modulation, and for rectifier circuit, the direct current voltage of reference phase is U + and U-, is equivalent to forming a positive and negative power of taking the mid point. Compared with the inversion output, the sine wave with the mutual difference of 60 degrees of electrical angle is output by taking the middle point of the filter circuit as a reference point, and the sine wave forms an actual three-phase symmetrical waveform for the motor and generates a rotating magnetic field to drive the motor to rotate as same as the three-phase power supply principle of a power supply. The number of power switch devices adopted by the independent double-bridge arm frequency conversion type soft starter is one third less than that of a traditional frequency conversion circuit, the size of a frequency converter is reduced, the cost is reduced, and the frequency conversion circuit works efficiently by firstly converting frequency and then regulating voltage in a control method.
Furthermore, a switching circuit is added to realize the soft start of a plurality of motors, the DSP controller utilizes a sine pulse width modulation technology, sine waves are used as modulation waves, triangular waves are used as carriers, generated PWM signals control four power switch tubes and a bidirectional thyristor T, and diodes are free-wheeling diodes of the switch tubes; the amplitude of the alternating current fundamental wave voltage output by the inverter unit can be controlled by changing the width of the rectangular pulse, and the output frequency of the alternating current fundamental wave voltage can be controlled by changing the modulation period, so that the control of the amplitude and the frequency of the voltage can be simultaneously output by the inverter circuit part, and the requirement of variable frequency speed regulation on the voltage and frequency coordination control is met.
Drawings
Fig. 1 is a topological diagram of the independent dual-bridge arm variable frequency soft starter of the present invention;
FIG. 2 is a voltage waveform diagram of the DC bus positive and negative ends of the independent dual-bridge arm variable frequency soft starter of the present invention with respect to the reference phase A (taking U1+ and U1-of the B phase as an example);
fig. 3 is a voltage waveform diagram of the reference phase a phase of the positive and negative terminals of the dc bus after the dc bus of the independent dual-bridge arm variable frequency soft starter of the present invention is connected in parallel with two capacitors C of the same capacity;
fig. 4 is an output voltage waveform diagram of the rectifying circuit of the independent dual-bridge arm variable-frequency soft starter of the present invention;
fig. 5 is a voltage waveform diagram of the dc bus of the independent dual-bridge arm variable frequency soft starter of the present invention after the dc bus is connected in parallel with two capacitors C with the same capacity;
fig. 6 is a diagram of the output voltage waveform of the inverter circuit of the independent dual-leg frequency-variable soft starter of the present invention relative to the reference phase w (a).
Detailed Description
The present invention will now be described in further detail with reference to the accompanying drawings, which are provided for purposes of illustration and not limitation.
As shown in fig. 1, an independent dual-bridge arm variable frequency soft starter includes two rectification inversion units, namely a first rectification inversion unit and a second rectification inversion unit, which are respectively connected to a power supply and a load, each rectification inversion unit is connected in parallel with a switch S, and a reference phase of the power supply is directly connected to another phase of the load.
The rectification inversion unit comprises a rectification circuit, a filter circuit, an inversion circuit, a bidirectional thyristor T and a switch K; the input end of the rectifying circuit is connected with one end of a power supply, the output end of the rectifying circuit is connected with the filter circuit, the output end of the filter circuit is connected with the inverter circuit, and the output end of the inverter circuit is connected with one end of a load through a switch K; the midpoint of the filter circuit is connected with the reference of the power supply through the bidirectional controllable silicon T and the switch S, and is used for fixing the potential of the reference phase, and the bidirectional controllable silicon T receives the control signal.
The rectifying circuit comprises two independent double-half-wave rectifying circuits, the rectifying circuit of the first rectifying and inverting unit comprises a diode D1 and a diode D2, and the filter circuit comprises a capacitor C1 and a capacitor C2.
The cathode of the diode D1 is connected with one end of the capacitor C1, the other end of the capacitor C1 is connected with one end of the capacitor C2, the other end of the capacitor C2 is connected with the anode of the diode D2, the cathode of the diode D2 is connected with the anode of the diode D1, the connection point of the cathode of the diode D2 and the anode of the diode D1 is connected with a power supply, and the midpoint E1 of the capacitor C1 and the capacitor C2 is connected with the reference of the power supply through the bidirectional thyristor T1 and the switch K3.
The rectifying circuit of the second rectifying and inverting unit comprises a diode D3 and a diode D4, the filter circuit comprises a capacitor C3 and a capacitor C4, the capacitor C3 and the capacitor C41 are connected with the reference of the power supply through a bidirectional thyristor T2 and a switch K3, and the rest of the connection modes are the same as the connection method of the rectifying circuit of the first rectifying and inverting unit, and are not described herein.
The inverter circuit of the first rectification inverter unit comprises a switching tube Q1, a switching tube Q2, a diode D5 and a diode D6.
The emitter of the switching tube Q1 is connected with the collector of the switching tube Q2, meanwhile, the connection point of the switching tube Q1 is connected with a load U through a switch K1, the collector of the switching tube Q1 is connected with one end of a filter circuit, and the two ends of the D5 of the diode are connected with the emitter and the collector of the switching tube Q1; the emitter of the switching tube Q2 is connected with the other end of the filter circuit, and the two ends of the D6 of the diode are connected with the emitter and the collector of the switching tube Q2; and the gates of the switching tube Q1 and the switching tube Q2 are connected with the DSP controller and used for receiving control signals.
The inverter circuit of the second rectification inverter unit includes a switching tube Q3, a switching tube Q4, a diode D7 and a diode D8, an emitter of the switching tube Q3 is connected to a collector of the switching tube Q4, and a connection point of the switching tube Q3 is connected to a load V through a switch K2, and the rest connection modes are the same as the connection method of the inverter circuit of the first rectification inverter unit, and are not described herein.
The input end of the first rectification inversion unit is connected with the B of the power supply, the output end of the first rectification inversion unit is connected with the U of the load through a switch K1, and the first rectification inversion unit is connected with a switch S1 in parallel; the input end of the second rectification inversion unit is connected with the C of the power supply, the output end of the second rectification inversion unit is connected with the V of the load through a switch K2, and the second rectification inversion unit is connected with a switch S2 in parallel; phase a of the power supply is connected to phase W of the load.
The switches K1, K2 and K3 are electronic switches or mechanical switches.
The independent double-bridge arm variable-frequency soft starter adopts independent double-phase bridge arms, each phase uses a double half-wave rectification circuit consisting of two diodes connected in series as a rectification part, uses a power switch tube connected in series as an inversion part, connects two capacitors C in series and then connects the two capacitors C in parallel at a direct current bus end, and uses the midpoints E1 and E2 of the two capacitors C as reference points to be connected with the phase A of a power supply and the phase W of variable-frequency output through bidirectional thyristors T1 and T2. The B phase and the C phase of the rectified input end use the A phase of three-phase alternating current as a reference point, and two input voltages UBA、UCAThe phase difference is 60 degrees; the outlet end of the single-phase rectification circuit is connected with the inlet end of the inverter circuit through a direct current bus, and the two capacitors C are connected in series and then connected in parallel on the direct current bus; the U phase and the V phase of the inversion output end are opposite to the two voltages U (phase A) of the phase W (phase A)UW、UVWAs output voltage, the voltage phases differ by 60 °.
The rectification circuit and the inverter circuit are respectively connected in series by adopting double diodes and double power switch tubes, the phase A of the three-phase alternating current power supply is connected with the phase W of the three-phase alternating current asynchronous motor, and the middle points E1 and E2 of two capacitors C with the same capacity are connected with the phase A of the three-phase alternating current power supply. The alternating voltage of the power grid is converted into direct voltage through the two-phase rectification circuit, then the voltage of the direct current bus is converted into alternating voltage with adjustable amplitude, frequency and phase through the inverter circuit, and similarly, the alternating voltage, the direct current, the alternating current and the alternating current are firstly subjected to alternating current-direct current frequency conversion and then are supplied to the asynchronous motor in a voltage and speed adjusting mode, and soft start control is performed.
UBA、UCAThe input voltage to the rectifier circuit is 60 ° out of phase. When U is turnedBAVoltage of>At 0, diode D1 is conducting; when U is turnedBAVoltage of<At 0, diode D2 is conducting; when U is turnedCAVoltage of>At 0, diode D3 is conducting; when U is turnedCAVoltage of<At 0, diode D4 conducts. For a separate double half-wave rectifier circuit, the resulting rectified output voltage of B with respect to the midpoint is shown in fig. 2; the direct-current voltage obtained by the soft starter passes through two capacitors C with the same capacity and connected with the direct-current bus in parallel to obtain a more stable direct-current voltage, and a waveform diagram is shown in fig. 3. Two capacitors C connected in series and having the same capacity have good filtering effect, and when the voltage is alternated, the voltage at two ends cannot be suddenly changed due to the charging and discharging effect of the capacitors, so that the stability of the voltage is ensured. As shown in FIG. 4, two capacitors C with the same capacity are not added, the output voltage of the rectifying circuit has large pulsation, and when the output voltage passes through the serial connection part of the two capacitors C with the same capacity, the obtained direct current voltage U isdAs shown in fig. 5, the larger the capacitance of the two capacitors C, the smaller the voltage ripple, and the voltage U on the dc bus is reduceddAs the input voltage of the inverter circuit.
The independent double-bridge arm inverter circuit adopts a full-control type device as a switch device, the basic working mode of the inverter circuit still adopts a 180-degree conduction mode, the conduction angle of each bridge arm is 180 degrees, the upper arm and the lower arm of the same phase conduct alternately, and the angle difference between the other two phases and the reference phase for starting conduction is 60 degrees.
The independent double-bridge-arm variable-frequency soft starter drives the motor to a preset rotating speed in a variable-frequency mode, and then drives the motor to a rated rotating speed in a voltage-regulating and speed-regulating mode.
In the frequency conversion process, a sinusoidal pulse width modulation technology is adopted to generate PWM signals to control four power switching tubes of Q1, Q2, Q3 and Q4; the amplitude of the alternating current fundamental wave voltage output by the inverter unit is controlled by changing the width of the rectangular pulse, the output frequency of the alternating current fundamental wave voltage is controlled by changing the modulation period, and therefore the control of the amplitude and the frequency of the voltage is output at the same time at the inverter circuit part. The phase difference of the basic output of the former is 60 degrees, and the phase difference of the latter is controlled by taking a space voltage vector comprehensive vector or a flux linkage track as a circle.
In the voltage and speed regulating process, the bidirectional thyristors T1 and T2 of the two rectification inversion units are switched off, the thyristor function is realized by the switching tube, the effective value of the output voltage is increased by continuously changing the conduction angle to change the rotating speed of the motor, and the frequency conversion type soft starter is switched out of the motor by using the change-over switch S and the switch K after the motor reaches the rated rotating speed.
The operation of the inverter circuit is analyzed as follows, and as shown in fig. 6, the output voltage U of two phases of the load U, V with respect to the reference phase Wuw、Uvw：
For the U phase, when the switch tube Q1 is conducted, UuwHas a voltage of Vba，VbaI.e. dc bus U1+For the voltage of reference point A phase, when the switch tube Q2 is conducted, UuwVoltage of the DC bus U1-To reference the voltage of phase a.
For the V phase, when the switch tube Q3 is conducted, UvwHas a voltage of Vca,，VcaI.e. dc bus U2+For the voltage of reference point A phase, when the switch tube Q4 is conducted, UvwVoltage of the DC bus U2-To reference the voltage of phase a.
A control method of an independent double-bridge arm variable-frequency soft starter is as follows:
a sine pulse width modulation method, namely SPWM control, is adopted, sine waves are selected as modulation waves in the control method, triangular carrier waves are selected as carriers, and isosceles triangular waves are selected as carrier waves, so that the control method has the characteristic of symmetry. The two interact, the intersection point formed in the positive half period is used as the moment point when the switching tube device is turned on, and the intersection point formed in the negative half period is used as the moment point when the switching tube device is turned off, so that the PWM square wave with the sine wave change rule is generated, and the SPWM is called.
For an inverter circuit in the independent double-bridge arm variable frequency soft starter, the PWM control of the two phases of the load U, V shares a triangular carrier UcTwo-phase sinusoidal modulation signal U of load U, Vru、 UrvThe phase difference is 60 degrees in sequence, so that the inverter bridge can output U with the phase difference of 60 degrees by taking the W phase as a reference phaseUW、UVWThe control rule of U, V two-phase switch tube is the same, when modulating signal UrAnd carrier UcThe crossing point of the three-phase alternating current motor controls the on-off of the switching tubes Q1, Q2, Q3 and Q4.
For U phase, when Uru>UcWhen the voltage is applied, a conducting signal is provided for the switching tube Q1, and a switching-off signal is provided for the switching tube Q2, so that the voltage between two phases of UW is obtained; when a conducting signal is applied to the switching tube Q1, the switching tube Q1 is conducted or the parallel diode is conducted in a follow current mode; when a conducting signal is applied to the switching tube Q2, the switching tube Q2 is conducted or the diode freewheeling diode connected in parallel is conducted; for the V phase, when Urv>UcWhen the voltage is applied, a conducting signal is provided for the switching tube Q3, and a switching signal is provided for the switching tube Q4, so that the voltage between two phases of the VW is obtained; when a conducting signal is applied to the switching tube Q3, the switching tube Q3 is conducted or the parallel diode is conducted in a follow current mode; when a conducting signal is applied to the switching tube Q4, the switching tube Q4 is conducted or the parallel diode is conducted in a freewheeling state.
After the motor reaches a certain rotating speed, the motor enters a voltage and speed regulating process, and the marks are that the switches T1 and T2 are disconnected. At this time, the diode D1, the diode D2, the capacitor C1 and the capacitor C2 in the A phase circuit are not in effect, and a phase-controlled voltage regulating circuit is formed from the A phase of the power supply through the switch tube Q1 and the switch tube Q2 when the power supply voltage U isBA>When the voltage is 0, the switch tube Q2 is switched off, the conduction angle of the switch tube Q1 is changed, and the effective value of the output forward voltage is changed; when power source end UBA<When the voltage is 0, the switching tube Q1 is switched off, the conduction angle of the switching tube Q2 is changed, and the effective value of the output negative voltage is changed; similarly for the V phase, when the power source terminal UCA>When the voltage is 0, the switching tube Q4 is switched off, the conduction angle of the switching tube Q3 is continuously changed, and the effective value of the output forward voltage is changed; when power source end UCA<When the voltage is 0, the switching tube Q3 is switched off, the conduction angle of the switching tube Q4 is changed continuously, the effective value of the output negative voltage is changed continuously, and the rotating speed of the motor is changed accordingly.
After the motor reaches the rated rotation speed, the switch tube Q1 and the switch tube Q2 are in a full-on state, then the change-over switch S1 and the change-over switch S2 are closed, and the switches K1, K2 and K3 are opened, so that the bypass switching is realized, and the soft starter exits.
Although the PWM driving signals of the upper and lower bridge arms of the same phase are complementary, in practice, in order to prevent the short circuit caused by the direct connection of the upper and lower switching tubes, a small dead time of the turn-off signals of the upper and lower switching tubes is left when the on-off of the upper and lower switching tubes are switched.
The utility model discloses this kind of soft starter will adopt independent double-phase uncontrollable rectifier circuit as the rectification part, and the mid point that the rectification output has increased series filter capacitance is connected for the reference point and the A looks of power and the W looks reference point of three phase machine. The bridge arm of an independent two-phase inverter circuit is used as an inverter part, and the middle part adopts a series electrolytic capacitor circuit. The utility model discloses a double-phase contravariant output is corresponding to the U looks and the V looks of motor respectively, and foretell mid point corresponds the W looks of motor.
Relative to the rectifying circuit, the direct current voltage taking the phase A as a reference is U + and U-, which is equivalent to forming a positive and negative power supply with a midpoint. Compared with the inversion output, the SPWM wave with the mutual difference of 60 degrees in electrical angle is output by taking the middle point of the series capacitor (the A phase of the alternating current power supply and the W phase of the motor) as a reference point, and like the three-phase power supply principle of the power supply, the SPWM wave forms an actual three-phase symmetrical waveform for the motor, generates a rotating magnetic field and drives the motor to rotate. After the frequency modulation process, the two-phase voltage and speed regulation of the motor is realized by a full-control type switch tube, and a fling-cut switch is added to enable the soft starter to quit operation when the motor reaches a rated rotating speed.
The utility model discloses synthesize and consider traditional three-phase AC-DC-AC converter not enough and defect when being used for soft start, the constant torque that performance variable frequency speed governing had simultaneously again and the advantage that rated current started, through adopting the design of independent double bridge arm inverter type soft starter, realize the soft start control to the high starting torque of motor and low starting current. The variable-frequency soft starter has the advantages of high reliability, small size, low cost, easiness in realizing functions of bypass switching and the like by combining the advantage of bypass switching of the silicon controlled soft starter.
The utility model discloses an independent double-bridge arm frequency conversion type soft starter, which comprises two independent rectifying circuits, two inverter circuits, four capacitors C with the same capacity, two bidirectional thyristors, and switching S and K switches; the rectifier bridge is used as a rectifying part, the inverter circuit is used as an inverter part, and the wire outlet end of the rectifying circuit is connected with the wire inlet end of the inverter circuit through a direct current bus; two-phase inversion output of the three-phase alternating current respectively corresponds to a U phase and a V phase of the motor, and the middle point of the two capacitors C corresponds to a W phase of the motor; the two capacitors C are connected in series and then connected in parallel at the end of the direct current bus, and the midpoint of the two capacitors C is used as a reference point to be connected with the phase A of the power supply and the phase W of the variable frequency output through the bidirectional triode thyristor. The utility model discloses an independent double bridge arm frequency conversion type soft starter reduces the difference between converter and the soft starter, reduces the power switch device in the traditional alternating current-direct current alternating frequency circuit, adopts independent double bridge arm frequency conversion type soft starter, realizes the efficient soft start of motor to but the switching, the reliability is high, small, with low costs. The control method adopts sine wave pulse width modulation frequency conversion and voltage and speed regulation to realize high-efficiency work of the circuit.
The above contents are only for explaining the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby, and any modification made on the basis of the technical solution according to the technical idea of the present invention all fall within the protection scope of the claims of the present invention.
Claims (7)
1. An independent double-bridge arm variable frequency soft starter is characterized by comprising two rectification inversion units, wherein the two rectification inversion units are respectively connected with two phases of a power supply and a load;
the rectification inversion unit comprises a rectification circuit, a filter circuit, an inversion circuit, a bidirectional thyristor T and a switch K;
the input end of the rectifying circuit is connected with one end of the power supply, the output end of the rectifying circuit is connected with the filter circuit, the output end of the filter circuit is connected with the inverter circuit, and the output end of the inverter circuit is connected with one end of the load through a switch K;
the midpoint of the filter circuit is connected with the reference of a power supply through a bidirectional thyristor T and a switch S and is used for fixing the potential of a reference phase, and the bidirectional thyristor T receives a control signal;
and the PWM control signal input by the rectification inversion unit has a mutual difference of two-phase modulation waves of 60 degrees and a mutual difference of two-phase line voltages output by inversion of 60 degrees.
2. The independent dual leg variable frequency soft starter of claim 1 wherein the rectifier circuit comprises two independent dual half wave rectifier circuits.
3. The independent double-bridge arm variable-frequency soft starter according to claim 2, wherein the double half-wave rectification circuit comprises a diode D1 and a diode D2, and the filter circuit comprises a capacitor C1 and a capacitor C2;
the cathode of the diode D1 is connected with one end of a capacitor C1, the other end of the capacitor C1 is connected with one end of a capacitor C2, the other end of the capacitor C2 is connected with the anode of a diode D2, the cathode of a diode D2 is connected with the anode of a diode D1, the connection point of the cathode of the diode D2 and the anode of a diode D1 is connected with a power supply, and the midpoint E1 of the capacitor C1 and the capacitor C2 is connected with the reference of the power supply.
4. The independent double-bridge arm variable frequency soft starter of claim 3, wherein the capacitance of the capacitor C1 is the same as that of the capacitor C2.
5. The independent double-bridge arm variable-frequency soft starter of claim 1, wherein the inverter circuit comprises a switching tube Q1, a switching tube Q2, a diode D5 and a diode D6;
the emitter of the switching tube Q1 is connected with the collector of the switching tube Q2, meanwhile, the connection point of the switching tube Q1 is connected with a load through a switch K, the collector of the switching tube Q1 is connected with one end of the filter circuit, and the two ends of the D5 of the diode are connected with the emitter and the collector of the switching tube Q1;
the emitter of the switching tube Q2 is connected with the other end of the filter circuit, and the two ends of the D6 of the diode are connected with the emitter and the collector of the switching tube Q2;
and the gates of the switching tube Q1 and the switching tube Q2 are connected with the DSP controller and used for receiving control signals.
6. The independent double leg variable frequency soft starter of claim 1 wherein the switch K is an electronic switch or a mechanical switch.
7. The independent double-bridge arm frequency conversion type soft starter according to claim 1, wherein an input end of one of the rectification inverter units is connected with B of a power supply, and an output end of the rectification inverter unit is connected with U of a load; the input end of the other rectification inversion unit is connected with the C of the power supply, the output end of the other rectification inversion unit is connected with the V of the load, and the A phase of the power supply is connected with the W of the load.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021234669.4U CN212543681U (en) | 2020-06-29 | 2020-06-29 | Independent double-bridge arm variable frequency soft starter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202021234669.4U CN212543681U (en) | 2020-06-29 | 2020-06-29 | Independent double-bridge arm variable frequency soft starter |
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| Publication Number | Publication Date |
|---|---|
| CN212543681U true CN212543681U (en) | 2021-02-12 |
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| CN202021234669.4U Expired - Fee Related CN212543681U (en) | 2020-06-29 | 2020-06-29 | Independent double-bridge arm variable frequency soft starter |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20210212 |