CN106276653B

CN106276653B - Arm crane with novel frequency converter

Info

Publication number: CN106276653B
Application number: CN201610824409.4A
Authority: CN
Inventors: 鲁霄钢
Original assignee: Individual
Current assignee: Kunming Frontier Science And Technology Development Co ltd
Priority date: 2015-05-20
Filing date: 2015-05-20
Publication date: 2020-04-28
Anticipated expiration: 2035-05-20
Also published as: CN106379817A; CN106429895B; CN106335850B; CN106379819B; CN106276635A; CN106395646A; CN106379817B; CN106348190B; CN106276635B; CN106402203A; CN106395646B; CN106276654A; CN106429923A; CN106379820A; CN106379818A; CN106348187B; CN106429924A; CN106395648A; CN104973522B; CN106379818B

Abstract

The invention discloses a crane with a novel frequency converter, wherein a filtering decoupling circuit of the frequency converter is arranged at the input stage of the frequency converter, a rectifying circuit, a filtering circuit and an inverter circuit are sequentially connected, a power factor correction circuit is arranged between the rectifying circuit and the filtering circuit and connected to a power factor correction end of a microprocessor circuit, the inverter circuit is connected to a driving signal end of the microprocessor circuit, and a man-machine interface circuit is connected to the input end of the microprocessor circuit; wherein, inverter circuit includes power tube driver chip and six power tubes: the power tube driving chip is connected to a microprocessor of the microprocessor circuit so as to drive the corresponding power tube to be alternately switched on and off according to a pulse width modulation signal output by the microprocessor; the six power tubes are divided into three groups, each group of power tubes controls one phase winding of the motor, and a diode is correspondingly connected between the source electrode and the drain electrode of each power tube. The invention can improve the performance of the boom crane.

Description

Arm crane with novel frequency converter

The present invention is a divisional application of the chinese invention patent application having the patent application number "201510256850.2" and the name "jib crane" filed 20/05/2015 by the applicant, and the entire contents of the divisional application are incorporated in the present application.

Technical Field

The invention relates to hoisting machinery, in particular to a jib crane and subsystems or parts thereof.

Background

The crane includes hoisting mechanism, amplitude varying mechanism, rotating mechanism, etc. and can lift and transport heavy matter in certain cylindrical space. The hoisting mechanism of the jib crane comprises a winch, and a workpiece is hoisted by winding and unwinding a steel rope wound on a winding drum. There is certain not enough in the design of current cantilever crane formula hoist engine: for example, the drum body and the drum shaft of the drum have complex structures and are not convenient to install; for another example, the braking effect of the brake is not ideal enough, the upper and lower parking limit devices are easy to lose effectiveness, and safety accidents are possibly caused; for another example, the winding manner of the steel rope is not reasonable enough, and the problem that the steel rope is loosened or wound together sometimes occurs, thereby increasing the potential safety hazard; in addition, the speed of the hoist cannot be conveniently adjusted; and so on. In view of the above-mentioned shortcomings, there is a need for an improved crane and hoist.

Disclosure of Invention

Aiming at the defects in the prior art, the embodiment of the invention aims to improve the complete machine, the subsystem or the component of the jib crane so as to improve the performance of a product.

In order to solve the above technical problems, an embodiment of the present invention provides an arm crane equipped with a novel frequency converter, including a chassis, a turntable, a winch, a lifting cylinder, an arm support, and a hook, wherein the turntable is mounted on the chassis, the winch is mounted on the turntable, the head end of the arm support is hinged to the turntable, the hook is suspended at the tail end of the arm support, one end of the lifting cylinder is hinged to the turntable, the other end of the lifting cylinder is hinged to the arm support, and the winch is provided with a driving device, a winding device, a braking device, and a control device: the driving device is provided with a motor, a coupler and a speed reducer, the speed reducer is arranged at the upper part of the rack, and a high-speed shaft of the speed reducer is connected with a power output shaft of the motor through the coupler; a winding drum supporting structure of the winding device is arranged on the upper part of the rack, one end of the winding drum is rotationally connected to the winding drum supporting structure, the other end of the winding drum is in transmission connection with a low-speed shaft of the speed reducer through a winding drum connecting structure, an upper pulley block of the winding device is positioned on the rack, and a steel rope is wound on the winding drum, the upper pulley block and the lower pulley block in a pattern winding manner; a brake of the braking device is arranged on a high-speed shaft of the speed reducer, and the speed reducer is braked by tightly holding a brake wheel; the control device is provided with a frequency converter for regulating the speed of the motor, a motor control loop is connected with a contactor in series between a motor protection circuit breaker and the frequency converter, and an upper limit switch and a lower limit switch are connected to the control loop of the contactor in series; the frequency converter is provided with a filtering decoupling circuit, a rectifying circuit, a filtering circuit, an inverter circuit, a power factor correcting circuit, a microprocessor circuit and a man-machine interface circuit, wherein the filtering decoupling circuit is arranged at the input stage of the frequency converter, the rectifying circuit, the filtering circuit and the inverter circuit are sequentially connected, the power factor correcting circuit is arranged between the rectifying circuit and the filtering circuit and connected to the power factor correcting end of the microprocessor circuit, the inverter circuit is connected to the driving signal end of the microprocessor circuit, and the man-machine interface circuit is connected to the input end of the microprocessor circuit; wherein, inverter circuit includes power tube driver chip and six power tubes: the power tube driving chip is connected to a microprocessor of the microprocessor circuit so as to drive the corresponding power tube to be alternately switched on and off according to a pulse width modulation signal output by the microprocessor; the six power tubes are divided into three groups, each group of power tubes controls one phase winding of the motor, and a diode is correspondingly connected between the source electrode and the drain electrode of each power tube.

Compared with the prior art, the embodiment of the invention improves the jib crane, so that the product performance can be improved, which is shown in the following aspects: the winding drum body, the winding drum shaft and the winding drum supporting and connecting structure of the winding drum body and the winding drum shaft are optimized, the winding drum is more reasonable in layout, more compact in structure and more convenient to install; the reel body structure, the steel rope winding mode and the rope pressing structure are improved, so that the problem that the steel ropes are loosened or wound together can be better avoided, and potential safety hazards can be eliminated; the brake, the lifting limiter and the motor stop control mechanism are improved, and the vehicle can be stopped and braked in time according to a preset intention under the conditions of limiting, emergency stopping and the like, so that safety accidents are effectively reduced; the frequency converter is adopted to regulate the speed of the winch motor, so that the lifting speed can be controlled in an aspect.

Drawings

FIG. 1 is a schematic view of a jib crane according to the present invention;

fig. 2 is a front view of the hoist of the present invention;

fig. 3 is a top view of the hoist of the present invention;

FIG. 4 is a right side view of the hoist of the present invention;

FIG. 5 is a schematic view of the brake of the present invention;

FIG. 6 is a schematic view of the steel cord winding structure of the present invention;

FIG. 7 is a schematic view of the spool and spool coupling structure, the rope pressing structure and the spool support structure of the present invention;

FIG. 8 is a front view of the reel body of the present invention;

FIG. 9 is a longitudinal cross-sectional view of the mandrel body of the present invention;

FIG. 10 is a schematic view of the spool shaft of the present invention;

FIG. 11 is a schematic view of the reel coupling structure of the present invention;

FIG. 12 is a schematic view of a pressing rope structure according to the present invention;

FIG. 13 is a schematic view of a roll support structure of the present invention;

FIG. 14 is a schematic view of a lift stop according to the present invention;

FIG. 15 is a schematic view of the internal structure of the lift stop of the present invention;

FIG. 16 is an electrical schematic of the motor stop control mechanism of the present invention;

FIG. 17 is an electrical connection diagram of a limit switch of the motor stop control mechanism of the present invention;

FIG. 18 is a block diagram of the motor speed regulation system of the present invention;

FIG. 19 is a schematic block circuit diagram of the frequency converter of the present invention;

fig. 20 is a schematic circuit diagram of the inverter of the present invention.

Detailed Description

For a better understanding of the technical principles and the working processes of the embodiments of the present invention, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.

Fig. 1-20 illustrate the construction of the hoist, subsystem or components of the present invention, wherein like reference numerals refer to like components.

Referring to fig. 1, the structure of the jib crane of the present invention is shown. The arm crane comprises a chassis S1, a rotary table S2, a winch S3, a lifting oil cylinder S4, an arm support S5, a lifting hook S6 and the like, wherein the rotary table S2 is mounted on the chassis S1, the winch S3 is mounted on the rotary table, the head end of the arm support S5 is hinged to the rotary table S2, the lifting hook S6 is suspended at the tail end of the arm support S5, one end of the lifting oil cylinder S4 is hinged to the rotary table S2, and the other end of the lifting oil cylinder S4 is hinged to the arm support S5. The rotation of the rotary table S2 enables the arm support S5 to rotate, the oil cylinder S4 stretches to enable the arm support S5 to ascend and descend, the variable-speed oil cylinder (not shown) enables the arm support S5 to change the amplitude, and the winch S3 collects and releases steel ropes wound on a winding drum, an arm support pulley block and a hook pulley block to lift a workpiece on a hook S6. The invention makes many improvements to the hoist S3 and its subsystems and components, as further described below.

Referring to fig. 2-4, the whole structure of the hoist of the present invention is shown. The winding machine comprises a driving device, a winding device, a braking device and a control device (not shown): the driving device comprises a motor M01 (preferably a variable frequency motor), a coupler 7, a speed reducer 1 and other parts, wherein the motor M01, the coupler 7 and the speed reducer 1 are sequentially connected; the winding device comprises a winding drum 2, an upper pulley block 3, a lower pulley block, a steel rope and the like, wherein the winding drum 2 is in transmission connection with the speed reducer 1 so that the winding drum 2 rotates, and the steel rope is wound on the winding drum 2, the upper pulley block 3 and the lower pulley block to be wound and unwound; the brake device is composed of a brake 5 and accessories, and the brake 5 acts on a high-speed shaft or a low-speed shaft of the speed reducer 1 to brake; the control device is provided with a motor stopping control mechanism which stops the motor from running when the motor stopping control mechanism is at the preset upper limit or lower limit.

As shown in fig. 2 to 4, the specific structure of the hoist is as follows: the speed reducer 1 and the winding drum supporting structure 4 are arranged on the upper part of the rack S01, one end of the winding drum 2 is rotatably connected to the winding drum supporting structure 4, the other end of the winding drum 2 is in transmission connection with a low-speed shaft of the speed reducer 1 through a winding drum connecting structure 8, and the high-speed shaft of the speed reducer 1 is connected with a power output shaft of a motor M01 through a coupling (a coupling shell cover is arranged outside) 7; the upper pulley block 3 is positioned on the frame S01, the steel rope is wound on the winding drum 2, the upper pulley block 3 and the lower pulley block in a certain pattern winding way, and the steel rope is correspondingly wound and unwound when the motor M01 rotates forwards or reversely; the brake 5 is attached to the reduction gear 1 and can hold the brake wheel 6 on the high-speed shaft of the reduction gear 1 tightly during braking.

In the winch, the winding drum body, the winding drum shaft and the winding drum supporting and connecting structure thereof are optimized, the winding drum is more reasonable in layout, more compact in structure and more convenient to install; the drum body structure, the steel rope winding mode and the rope pressing mechanism are improved, the problem that the steel ropes are loosened or wound together can be better avoided, and potential safety hazards can be eliminated; the brake, the lifting limiter and the motor stop control mechanism are improved, and the vehicle can be stopped and braked in time according to a preset intention under the conditions of limiting, emergency stopping and the like, so that safety accidents are effectively reduced. As described further below.

Fig. 2 to 4 show a brake mounting structure in which the brake 5 is mounted on the high-speed shaft of the speed reducer 1, and the speed reducer 1 and thus the drum 2 on the low-speed shaft of the speed reducer 1 are braked by clasping the brake wheel 6. The structure of the brake will be described in further detail below.

Referring to fig. 5, the structure of the brake of the present invention is shown. In the brake 5, one end of a first brake arm 52, a second brake arm 53, a driving telescopic rod (which can be an air cylinder or an oil cylinder) 59 with a driving device 50 and one end of a driven telescopic rod 58 are respectively hinged to a brake base 51; the other ends of the first brake arm 52, the driving telescopic rod 59 and the driven telescopic rod 58 are respectively hinged to one arm of the L-shaped connecting rod 57; the other end of the second brake arm 53 is hinged with the linear connecting rod 55, and the other end of the linear connecting rod 55 is hinged with the other arm of the L-shaped connecting rod 57; the first brake pad 56 is attached to the inner side of the first brake arm 52, the second brake pad 54 is attached to the inner side of the second brake arm 53, and the inner arc surface of the first brake pad 56 and the inner arc surface of the second brake pad 54 hold the brake drum 6 on the high speed shaft of the reduction gear 1 during braking. The braking mode has the advantages of simple structure, quick braking response and better effect.

Referring to fig. 6, the steel cord winding structure of the present invention is shown. In the steel rope winding structure, a steel rope 10 is wound on a winding drum 2, an upper pulley (arm support pulley) group 3 and a lower pulley (hook pulley) group 9 in the following way: the first end of steel cable 10 is around in the first end of reel 2 and is fixed in first pressure rope position 2a, the second end of steel cable 10 is around in the second end of reel 2 and is fixed in reel 2 second pressure rope position 2d, steel cable 10 is from reel 2 first leading rope position 2b counter-clockwise direction winding-out, first lower pulley 91 is walked around to counter-clockwise in proper order, first upper pulley 31, second lower pulley 92, second upper pulley 32, again in proper order clockwise after third lower pulley 93 is walked around, third upper pulley 33, fourth lower pulley 94, again clockwise winding-back reel 2 second leading rope position 2 c. By adopting the winding method, the probability of the occurrence of the bad phenomena such as the winding and the loosening of the steel rope can be reduced.

Referring to fig. 7, the spool and spool coupling structure, rope pressing structure and spool support structure of the present invention are shown. The winding drum 2 includes a winding drum body 21 and a winding drum shaft 22, a first end of the winding drum shaft 22 is fixedly supported at a second end of the winding drum body 21, the first end of the winding drum body 21 is coupled with the low-speed shaft of the speed reducer 1 through a winding drum coupling structure (part I in fig. 7), and a second end of the winding drum shaft 22 is supported at a winding drum supporting structure (part III in fig. 7), so that the installation is very convenient. In addition, the upper parts of both ends of the winding drum body 21 are respectively provided with a rope pressing structure (part II in fig. 7), so that the end parts of the steel ropes 10 can be well fixed.

Referring also to fig. 8-9, the construction of the roll of the present invention is shown. This reel body 21 sets up first end plate 25, second end plate 24 and backup pad 23, and the first end plate 25 of reel body 21 passes through the low-speed coupling of reel hookup structure and speed reducer 1, and the second end plate 24 and the backup pad 23 fixed stay reel axle 22 of reel body 21, and this reel axle 22 is installed in reel bearing structure, and it is very convenient to install.

As shown in fig. 2 to 9, the spool body 21 is provided with the wire guide 211 thereon to facilitate the introduction/withdrawal of the wire 10 along the wire guide 211, thereby facilitating the orderly winding of the wire 10.

Referring to fig. 10, the structure of the spool shaft of the present invention is shown. This reel shaft 22 includes reel shaft main part 222, and the first end of reel shaft main part 222 sets up first shaft shoulder 221, and the second end of reel shaft main part 222 sets up second shaft shoulder 224 and third shaft shoulder 225, and wherein, the external diameter of reel shaft main part 222, first shaft shoulder 221, second shaft shoulder 224 and third shaft shoulder 225 reduces in proper order, and sets up toper transition portion 223 between reel shaft main part 222 and the second shaft shoulder 224, and this kind of reel shaft 22 structural strength is better, also easy to assemble.

Referring to FIG. 11, the spool coupling of the present invention is shown. In this reel coupling structure, the coupling half shaft 84 is supported by the cylindrical roller bearing 87 on the coupling disk 82, the baffle plate 86 is provided at the inner end of the coupling half shaft 84, the inner joint portion of the coupling half shaft 84, the cylindrical roller bearing 87 and the coupling disk 82 is closed by the inner cover plate 85, the outer joint portion of the coupling half shaft 84, the cylindrical roller bearing 87 and the coupling disk 82 is closed by the outer cover plate 83, the coupling disk 82 is fixed to the flange plate 81, and the flange plate 81 is fastened to the first end plate 25 on the reel body 21. The structure is reliable in connection and convenient to install.

Referring to fig. 12, the present invention is shown in a rope press configuration. The rope pressing structure 11 includes a wire pressing plate 111 having a wire pressing groove 1121 formed on a lower surface thereof, and the wire pressing plate 111 is fastened to a screw hole of the drum body 21 by a bolt 112 so that the wire 10 is securely fixed to the drum body 21 without being released, thereby increasing a safety factor.

Referring to FIG. 13, the roll support structure of the present invention is shown. In this reel support structure 4, a base bearing block 43 is provided on a support base 41, a reel bearing block 44 is supported by the base bearing block 43, a reel shaft 22 is supported by the reel bearing block 44 through a tapered roller bearing 45, the base bearing block 43, the inner joint portions of the reel bearing block 44 and the tapered roller bearing 45 are closed by an inner cover plate 42, and the outer joint portions of the base bearing block 43, the reel bearing block 44 and the tapered roller bearing 45 are closed by an outer cover plate 47. The structure is compact and the installation is convenient.

As shown in fig. 13, the present embodiment shows a mounting structure of a lift stopper. In fig. 12, the spool shaft 22 is provided with a spool shaft coupling plate 46 for mounting a driving end of the elevation stopper 12 (e.g., a rocker of the screw type elevation stopper 12), and when the rotation angle of the spool 2 exceeds a predetermined value (number of revolutions), the electrical connection is disconnected to prevent the spool from further rotating, so that the elevation height can be restricted. This is explained in further detail below in conjunction with fig. 12-14.

Referring to fig. 14-15, the lift stop construction of the present invention is shown. Referring also to fig. 12, the lifting stopper 12 includes a U-shaped bracket 121, a rocker 122, a screw 123, a rotating wheel 124, a stopper housing 125, a guide rod 126, a push plate 127, a movable conductive pillar 128, a limit switch 129, and a fixed conductive pillar 120: the U-shaped support 121 is fixed on the outer cover plate 47 connected with the winding drum shaft 22, the stopper shell 125 is fastened on the U-shaped support 121 through screws, the screw 123 is supported on the stopper shell 125, the push plate 127 is installed on the screw 123, one end of the movable conductive column 128 is connected to the push plate 127, the other end of the movable conductive column 128 is supported on one arm of a limit switch 129 fixedly connected with the stopper shell 125, the fixed conductive column 120 is fixed on the other arm of the limit switch 129, the rotating wheel 124 is installed at the end part of the screw 123, one end of the rocker 122 is eccentrically connected with the rotating wheel 124, and the other end of the rocker 122 is connected with the winding drum shaft coupling.

In addition, a guide rod 126 is further installed on the stopper housing 125, the guide rod 126 is arranged in parallel with the screw 123, and the push plate 127 is arranged through the guide rod 126 to slide so as to ensure smooth movement.

In this embodiment, the position of the pusher plate 127 can be pre-adjusted. When the reel 2 rolls, the rocker 122 rotates along with the reel shaft coupling plate 46, the screw 123 rotates through the rotating wheel 124, the push plate 127 translates to drive the movable conductive column 128 to separate from the fixed conductive column 120, so that the electrical connection is broken to play a limiting role, and the safety performance is improved.

Fig. 14-15 illustrate the construction of the lift stop 12, which can be used for both the upper and lower limits. The limit switch of the lifting limiter is connected to a control loop of a motor M01 of the winch, and the motor M01 is stopped by triggering a motor protection circuit breaker in the motor control loop, so that the safety protection effect is achieved.

The invention aims at preventing the upper limit and the lower limit from generating limit situations, and improves the aspect of an electrical control system, and the specific description is as follows.

Referring also to fig. 16-17, the circuit configuration of the motor stop control mechanism of the present invention is shown. The motor stop control mechanism can be used for a winch and other types of lifting devices, and has an electrical structure as follows: in a control loop of a motor M01, a contactor KM01 is additionally arranged between a motor protection circuit breaker QF01 and a frequency converter VF 01; the upper and lower limit switches SQ01, SQ02 are connected in series to the control loop of the contactor KM 01. Here, the terminals 1 to 6 of the motor protection breaker QF01, a1 and a2 (three sets of terminals 1 and 2) of the contactor KM01, the terminal R, S, T, V, W, PE of the inverter VF01, the

terminals

11 and 12 of the limit switches SQ01 and SQ02, and the

terminals

13 and 14 of the limit unlocking key knob SB01 are connected according to fig. 15 and 16, and detailed description thereof is omitted.

When the limit switch SQ01 or SQ02 is triggered, the coil power supply of the contactor KM01 is directly cut off, the contactor KM01 is released, and therefore the power supply of a frequency converter VF01 loop is cut off, and the operation of the motor M01 is rapidly stopped; thereafter, unlocking is possible by rotating the limit unlocking key knob SB 01. By the control mode, intermediate links for processing the limit signals are reduced, so that the motor can be immediately stopped when a fault occurs, and the damage of equipment and the casualties of personnel are avoided.

In order to change the speed of the winch S3 conveniently, the invention adopts the variable frequency speed control of the motor. The following description is made.

Referring to fig. 18, a block diagram of the motor governor system of the present invention is shown. The motor speed regulating system comprises a power supply M03, a frequency converter M02 and a motor M01 which are sequentially connected, wherein the frequency converter M02 adopts an AC-DC-AC mode, firstly, a power frequency AC power supply M03 is converted into a DC power supply through a rectifier, then, the DC power supply is converted into an AC power supply with controllable frequency and voltage through an inverter so as to be supplied to the motor M01, and thus, the rotating speed of the motor M01 can be changed by changing the frequency.

As shown in fig. 18, the input stage of the frequency converter M02 is provided with a filtering decoupling circuit, which is preferably an RC filtering decoupling circuit, and is composed of a current limiting resistor R and a filtering capacitor C connected in series, so that the output positive terminal and the output ground terminal of the power supply M03 are connected to the current limiting resistor R and the filtering capacitor C connected in series. The filtering decoupling circuit is used as a preposed analog low-pass filter of an alternating current signal input channel and has the function of resisting interference; a decoupling capacitor is connected between two terminals of the AC/DC signal input channel, and can provide a bypass for high-frequency differential mode interference signals.

Referring to fig. 19, a schematic block circuit diagram of the frequency converter of the present invention is shown. The frequency converter M02 of the present embodiment includes a rectifier circuit M021, a power factor correction circuit M022, a filter circuit M023, an inverter circuit M024, a microprocessor circuit M025, a man-machine interface circuit M026, and the like, wherein: the rectifier circuit M021 is composed of a rectifier diode or a bridge stack (preferably, a full-bridge rectifier circuit), and includes a necessary interference filtering circuit, and its main function is to convert ac power into dc power; the power factor correction circuit M022 is an optional component, consists of a power semiconductor and a control chip, and is also connected to a power factor correction terminal of the microprocessor circuit M025 to make the input current close to sine wave, reduce the harmonic content of the power grid and realize the purpose of improving the power factor; the filter circuit M023 (preferably, an RC filter circuit) is mainly composed of elements such as an electrolytic capacitor and the like, and performs filtering smoothing and energy storage of direct current; the inverter circuit M024 consists of a power module and a driving circuit, wherein the power module can be an intelligent power driving tube chip and is also connected to a driving signal end of the microprocessor circuit, and the inverter circuit has the main functions of completing the conversion of direct current to three-phase alternating current and realizing the aims of frequency modulation and voltage regulation; the microprocessor circuit M025 is composed of a microprocessor (DSP) and peripheral circuits, and issues a corresponding instruction signal according to a command issued by the human-machine interface circuit M026, controls the operation of the power factor correction circuit M022 and the inverter circuit M024, and performs necessary circuit protection and fault processing according to circuit feedback information. Thus, the embodiment controls the output mode of the frequency converter M02 through the microprocessor circuit, which is beneficial to flexibly outputting the voltage according to the preset requirement, thereby meeting the requirements of different users.

Referring to fig. 20, a circuit schematic of the inverter of the present invention is shown. Specifically, an example of an inverter circuit M024 and a microprocessor circuit for the motor M01 is described as follows: the commercial power is converted into direct current through the rectifying circuit M021, filtered by the electrolytic capacitor and then connected to the power input end of the inverter circuit M024, and a filter capacitor is connected between the power input ends. The microprocessor of the microprocessor circuit controls the motor M01 according to the setting signal of the human-computer interface circuit.

In this embodiment, the inverter circuit M024 includes a power tube driving chip, and the power tube driving chip is connected to a microprocessor (MCU/DSP) of the microprocessor circuit, so as to drive the corresponding power tube to alternately turn on and off according to a pulse width modulation signal output by the microprocessor. Specifically, the inverter circuit M024 includes six power tubes Q1-Q6, the six power tubes are divided into three groups, and each group of power tubes controls one phase winding of the three-phase motor M01.

The specific connection mode of each power tube is as follows: the source electrodes of the power tubes Q1, Q2 and Q3 are connected with one end of a direct current power supply, the drain electrodes of the power tubes Q4, Q5 and Q6 are connected with the other end of the direct current power supply, the connection point of the drain electrode of the power tube Q1 and the source electrode of the power tube Q4 is connected with a U-phase terminal of the motor, the connection point of the drain electrode of the power tube Q2 and the source electrode of the power tube Q5 is connected with a V-phase terminal of the motor, and the connection point of the drain electrode of the power tube Q3 and the source electrode of the power tube Q6 is connected with a W-; the gates of the power transistors Q1, Q2, Q3, Q4, Q5 and Q6 are respectively connected to an output terminal of the power transistor driving chip, and each input terminal of the power transistor driving chip is respectively controlled by one of the output pulse width adjusting signals PWM1, PWM2, PWM3, PWM4, PWM5 and PWM6 of the microprocessor circuit. Diodes D1-D6 are correspondingly connected between the source electrodes and the drain electrodes of the six power tubes Q1-Q6.

When the motor is started, the microprocessor generates corresponding 6 paths of pulse width modulation signals, namely driving signals PWM 1-PWM 6, according to the set motor rotating speed; 6 power tubes (MOSFET or IGBT) Q1-Q6 of the inverter M024 are driven by a power tube driving chip; the power tubes are alternately switched on and off to generate three-phase modulation waveforms, and three-phase alternating current with adjustable output voltage and variable frequency is output to a U, V, W terminal of the motor M01, so that stepless variable frequency speed regulation of the motor M01 is realized.

Although the present invention has been described with reference to the preferred embodiments, it is not intended to be limited thereto, and variations and modifications may be made by those skilled in the art without departing from the spirit and scope of the present invention.

Claims

1. A boom crane provided with a novel frequency converter comprises a chassis, a rotary table, a winch, a lifting oil cylinder, a variable speed oil cylinder, a boom and a lifting hook, wherein the rotary table is arranged on the chassis to enable the boom to rotate; the hoist is provided with a driving device, a winding device, a braking device and a control device: the driving device is provided with a motor, a coupler and a speed reducer, the motor coupler and the speed reducer are sequentially connected, the speed reducer is arranged at the upper part of the rack, and a high-speed shaft of the speed reducer is connected with a power output shaft of the motor through the coupler; coiling mechanism includes reel, upper pulley group, lower pulley group and steel cable, and the reel disposes reel draw bail, pressure rope structure and reel bearing structure, and the reel bearing structure of speed reducer and reel installs in frame upper portion, and the one end of reel is rotated and is connected in reel bearing structure, and the other end of reel passes through the reel draw bail transmission and connects in the low-speed axle of speed reducer, wherein: the winding drum body of the winding drum is provided with a first end plate, a second end plate and a support plate, the first end plate of the winding drum body is connected with a low-speed shaft of the speed reducer through a winding drum connecting structure, and the second end plate of the winding drum body and the support plate fixedly support the winding drum shaft; the winding drum shaft of the winding drum comprises a winding drum shaft main body, a first shaft shoulder is arranged at the first end of the winding drum shaft main body, a second shaft shoulder and a third shaft shoulder are arranged at the second end of the winding drum shaft main body, the outer diameters of the winding drum shaft main body, the first shaft shoulder, the second shaft shoulder and the third shaft shoulder are sequentially reduced, and a conical transition part is arranged between the winding drum shaft main body and the second shaft shoulder; in the reel supporting structure, a support base is provided with a machine base bearing seat, the reel bearing seat is supported on the machine base bearing seat, a reel shaft is supported on the reel bearing seat through a tapered roller bearing, the machine base bearing seat, the inner side combination part of the reel bearing seat and the tapered roller bearing are blocked by an inner cover plate, and the outer side combination part of the machine base bearing seat, the reel bearing seat and the tapered roller bearing is blocked by an outer cover plate; the two ends of the winding drum are respectively provided with a rope pressing structure for fixing the end part of the steel rope, the upper pulley block of the winding device is positioned on the frame, the steel rope is wound on the winding drum, the upper pulley block and the lower pulley block in a pattern winding way, the winding drum body of the winding drum is provided with a steel rope guide groove for leading in/out the steel rope along the steel rope guide groove, wherein the steel rope is wound out from the first rope guiding position of the winding drum in the anticlockwise direction, sequentially wound around the first lower pulley, the first upper pulley, the second lower pulley and the second upper pulley in the anticlockwise direction, sequentially wound around the third lower pulley, the third upper pulley and the fourth lower pulley in the clockwise direction, and then wound back to the second rope guiding position of the winding drum in the clockwise direction, the first end of the steel rope is wound on the first end of the winding drum and fixed at the first rope pressing position, the second end of the steel rope is wound on the second end of the winding drum and fixed at the second rope pressing position of the winding drum, and the steel rope is fixed at the two ends of the winding drum through corresponding rope pressing structures; a brake of the braking device is arranged on a high-speed shaft of the speed reducer, and the speed reducer is braked by tightly holding a brake wheel on the high-speed shaft of the speed reducer, so that a winding drum on a low-speed shaft of the speed reducer is braked; controlling means sets up the converter and comes the speed governing to the motor, and controlling means sets up motor stop control mechanism and comes stop motor operation when predetermined upper limit or lower spacing, wherein: the motor control loop is connected with a contactor in series between the motor protection circuit breaker and the frequency converter, the upper limit switch and the lower limit switch are connected to the control loop of the contactor in series, and the coil power supply of the contactor is directly cut off after the upper limit switch or the lower limit switch is triggered, so that the contactor is released to cut off the loop power supply of the frequency converter to quickly stop the motor from running; the frequency converter is characterized by being provided with a filtering decoupling circuit, a rectifying circuit, a filtering circuit, an inverter circuit, a power factor correcting circuit, a microprocessor circuit and a man-machine interface circuit, wherein the filtering decoupling circuit is arranged at the input stage of the frequency converter; wherein, inverter circuit includes power tube driver chip and six power tubes: the power tube driving chip is connected to a microprocessor of the microprocessor circuit so as to drive the corresponding power tube to be alternately switched on and off according to a pulse width modulation signal output by the microprocessor; the six power tubes are divided into three groups, each group of power tubes controls one phase winding of the motor, and a diode is correspondingly connected between the source electrode and the drain electrode of each power tube.

2. The boom crane of claim 1 wherein the filter decoupling circuit comprises a current limiting resistor R and a filter capacitor C connected in series to form an RC filter decoupling circuit.

3. Jib crane according to claim 1 or 2, wherein the control circuit of the contactor is provided with a limit release knob, which is connected in parallel with the upper and lower limit switches.