CN111355383A - Low-frequency direct-drive high-voltage frequency converter of elevator - Google Patents
Low-frequency direct-drive high-voltage frequency converter of elevator Download PDFInfo
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- CN111355383A CN111355383A CN202010288270.2A CN202010288270A CN111355383A CN 111355383 A CN111355383 A CN 111355383A CN 202010288270 A CN202010288270 A CN 202010288270A CN 111355383 A CN111355383 A CN 111355383A
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- 230000007246 mechanism Effects 0.000 claims description 15
- 238000004891 communication Methods 0.000 claims description 11
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- 239000013307 optical fiber Substances 0.000 claims description 5
- 238000005516 engineering process Methods 0.000 abstract description 2
- 238000012423 maintenance Methods 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 15
- 230000008569 process Effects 0.000 description 8
- 230000005540 biological transmission Effects 0.000 description 7
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- 238000001816 cooling Methods 0.000 description 4
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- 239000003638 chemical reducing agent Substances 0.000 description 2
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
- H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
- H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
- H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
- H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
- H02M5/4585—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only having a rectifier with controlled elements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66B—ELEVATORS; ESCALATORS OR MOVING WALKWAYS
- B66B11/00—Main component parts of lifts in, or associated with, buildings or other structures
- B66B11/04—Driving gear ; Details thereof, e.g. seals
- B66B11/043—Driving gear ; Details thereof, e.g. seals actuated by rotating motor; Details, e.g. ventilation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B66—HOISTING; LIFTING; HAULING
- B66B—ELEVATORS; ESCALATORS OR MOVING WALKWAYS
- B66B5/00—Applications of checking, fault-correcting, or safety devices in elevators
- B66B5/02—Applications of checking, fault-correcting, or safety devices in elevators responsive to abnormal operating conditions
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
- H02M5/02—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc
- H02M5/04—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters
- H02M5/10—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases without intermediate conversion into dc by static converters using transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters
- H02P27/08—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation
- H02P27/14—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using dc to ac converters or inverters with pulse width modulation with three or more levels of voltage
Abstract
The invention belongs to the technology of special high-voltage frequency converters, and provides a low-frequency direct-drive high-voltage frequency converter of a hoister. The low-frequency direct-drive high-voltage frequency converter of the elevator comprises a rectifier transformer, a low-frequency power unit, a master control system and a high-precision encoder; rated capacity S of the rectifier transformer0At least according to the rated power P of the hoisting motore1.6 times of selection, i.e. S0≥1.6Pe(ii) a The rectifier transformer is provided with a group of primary windings and 3 xj groups of secondary windings;the primary winding is connected with a power supply high-voltage switch cabinet; rated capacity S of each set of secondary windings1=S0And/3 x j are connected with the three-phase input ends R, S, T of the low-frequency power units through power cables in one-to-one correspondence, so that the invention not only reduces the overall volume and weight of the equipment, but also saves the equipment investment and operation and maintenance cost, and has remarkable social and economic benefits.
Description
Technical Field
The invention belongs to the technology of special high-voltage frequency converters, and provides a low-frequency direct-drive high-voltage frequency converter of a hoister.
Background
The traditional high-voltage frequency converter is in a serial connection mode of H-bridge power units, wherein the H-bridge power units are of two-level and three-level types, and the two-level type is still mainly used in a more common mode. The problem is that the output rated frequency of the traditional four-quadrant high-voltage frequency converter applied to the elevator is 50Hz, the stable working frequency is usually 2-3 Hz and above, and the traditional four-quadrant high-voltage frequency converter can only be used for controlling the elevator taking a high-speed alternating-current motor (usually, the number of pole pairs p is 8 and below, and the rotating speed per minute is 370 rpm and above) as a power source according to the rotating speed per minute of the alternating-current motor n =60f/p (in the formula, f is the frequency, and p is the pole pair number of the alternating-current motor); the elevator works by driving the steel wire rope in a manner that a winding drum of the elevator winds or rubs, so that the aim of lifting personnel and materials up and down by a container hung at the tail end of the steel wire rope is fulfilled, safety regulations stipulate that, for example, a shaft is used, and the rated running speed of the lifting container is less than 0.6
The unit is meter/second, in the formula, h is lifting depth and meter, therefore, the rotating speed of the winding drum per minute is required to be dozens of revolutions and below, in order to match the rated rotating speed of the motor and the winding drum, the traditional lifting machine drives the winding drum by the motor through a speed reducer, and the defects of large occupied area of equipment, low transmission efficiency, small installed capacity, high capital cost for installing equipment buildings and the like exist.
In order to overcome the defects caused by the speed reducer of the traditional hoister, the advanced driving modes of the hoister are two, one is: the elevator is directly driven by a low-speed alternating current motor, namely, the elevator and the motor share a main shaft, and the main shaft is equivalent to a rotor of the alternating current motor; the second step is as follows: the low-speed alternating current motor, a winding drum of the hoisting machine and a main shaft device are integrated into a whole, namely the built-in hoisting machine is characterized in that a rotor device of the alternating current motor is embedded in the inner side of the winding drum, so that the winding drum is equivalent to a rotor of the alternating current motor, a stator device is embedded on the main shaft, and the main shaft of the hoisting machine is equivalent to a stator of the alternating current motor; the two advanced driving modes both urgently need various low-frequency direct-drive frequency converters, and are selected and matched by various elevators on the basis of high cost performance; in the above two driving methods, the motor is either external or internal, and for convenience of description, it is generally referred to as a lift motor in this specification.
The possibility that the main shaft elevator skip is loaded secondarily occasionally or is loaded continuously under the condition of not unloading completely requires that the elevator has large overload capacity, and an emergency lifting task can be completed safely and reliably under the condition of occasional serious overload and even under the condition that a low-frequency direct-drive frequency converter has local fault.
Disclosure of Invention
In order to solve the technical problems, the invention aims to provide a low-frequency direct-drive high-voltage frequency converter of a hoister, which is used for driving a low-speed direct-connection or built-in type hoister and comprises permanent magnets, separately excited low-speed synchronous machines and low-speed asynchronous machine types; the main performance indexes are that the stable output frequency range of the low-frequency direct-drive high-voltage frequency converter of the hoister is 0.1 Hz-17 Hz, the whole process is full of torque, and the overload multiple is more than 2 times, so that the requirements of stable speed regulation and safe operation of the low-speed direct-drive or built-in hoister are met.
The invention adopts the following technical scheme to achieve the aim of the invention:
a low-frequency direct-drive high-voltage frequency converter of a hoist comprises a rectifier transformer, a low-frequency power unit, a master control system and a high-precision encoder; rated capacity S of the rectifier transformer0At least according to the rated power P of the hoisting motore1.6 times of selection, i.e. S0≥1.6Pe(ii) a The rectifier transformer is provided with a group of primary windings and 3 xj groups of secondary windings; the primary winding is connected with a power supply high-voltage switch cabinet and receives power supply of a power grid; rated capacity S of each set of secondary windings1=S0And/or (3) and is connected with the three-phase input end R of the low-frequency power unit through a power cable,S, T, which are connected in a one-to-one correspondence manner and provide low-voltage alternating current for the low-frequency power units; the output ends of the low-frequency power units are marked as U and V and divided into three groups, the number of each group is also j, the output end U of the first low-frequency power unit in each group is connected together through a bus bar to form a neutral point of the low-frequency direct-drive high-voltage frequency converter of the elevator, the output ends V and U of two adjacent low-frequency power units in each group are sequentially connected in series through the bus bar, and the output end V of the last low-frequency power unit in each group is respectively connected with three phases of a stator winding of the elevator motor through a power cable to form three-phase output of the low-frequency direct-drive high-voltage frequency converter; the high-precision encoder is driven by a rotor of the lifting motor through a connecting mechanism, and the output end of the high-precision encoder is connected with the input end of the main control system through a shielded cable and used for detecting the rotating speed and angle of the rotor of the lifting motor to serve as important signals for the vector control of a speed closed loop and a rotor magnetic field orientation closed loop of the main control system; a PLC analog quantity output port in the lifting electric control system is connected with a signal input interface of the master control system through a shielded cable or is connected in a communication mode to serve as a frequency given signal of the low-frequency direct-drive high-voltage frequency converter of the lifting machine, and the master control system converts an instruction from the lifting electric control system into a control signal of frequency and moment; the main control system is connected with a main control board in the low-frequency power unit through optical fibers, and the low-frequency power unit outputs single-phase alternating current with variable frequency according to instructions of the main control system.
The low-frequency direct-drive high-voltage frequency converter of the hoister also comprises an exciting transformer and a rectifying device; the primary winding of the excitation transformer is connected with a power supply switch through a power cable to obtain an excitation power supply, the secondary winding of the excitation transformer is connected with the three-phase input end of the excitation rectifying device through a three-phase power cable, and the direct current output end of the excitation rectifying device is connected with the excitation winding of the lifting motor through a two-phase power cable to provide excitation current for the separately excited lifting motor.
The number j of the j groups of secondary windings is 3 or 5.
The number of stages of each phase of the low-frequency direct-drive high-voltage frequency converter of the elevator, which is connected in series with the low-frequency power unit, is determined by the voltage level of a stator winding of the elevator motor, and the voltage level is 6 or 10 kV.
The low-frequency power unit is a four-quadrant three-level low-frequency power unit; the low-frequency power unit mainly comprises a main loop part, an IGBT trigger module, a main control board and a DC/DC power module; the main loop part comprises a fast melting part, a three-phase AFE rectification feedback bridge, two groups of energy storage capacitors, a voltage-sharing resistor, a single-phase inverter bridge and a radiator; the three-phase AFE rectification feedback bridge and the single-phase inverter bridge are of a three-level structure, each phase of the three-level structure is composed of four IGBTs and a neutral point clamping element, and an upper bridge arm and a lower bridge arm are respectively provided with two IGBTs which are connected in series and are symmetrically arranged; the three-phase AFE rectification feedback bridge, the power devices IGBT and clamping diode in the single-phase inverter bridge, and the voltage-sharing resistor are distributed according to the principle of uniform heat dissipation and are arranged on the element surface of the radiator, so that the heat dissipation is facilitated; the fast fuse is at least two, and is connected in series between the input end R, S, T of the low-frequency power unit and the three-phase alternating current input end of the three-phase AFE rectification feedback bridge through a busbar, so that the main loop of the low-frequency power unit is quickly protected from overcurrent, and meanwhile, the short circuit between an in-phase upper bridge arm and an in-phase lower bridge arm or between phases is prevented; three layers of the laminated busbar respectively connect the three-phase AFE rectification feedback bridge, the single-phase inverter bridge, the two groups of energy storage capacitors and the anode, the zero point and the cathode of the voltage-sharing resistor together to form three levels (+ E, 0 and E) of the low-frequency power unit; the two groups of energy storage capacitors and the voltage-sharing resistor are respectively connected in parallel between a busbar (+ E and 0, and between 0 and-E), and the energy storage capacitors are connected with the voltage-sharing resistor in parallel so that the direct-current voltage values borne by the energy storage capacitors are basically consistent; the alternating current output end of the single-phase inverter bridge is connected to an output terminal through a busbar to form single-phase output ends U and V of the low-frequency power unit; the IGBT trigger module is connected with the IGBT trigger signal end through a twisted pair to provide a trigger signal with enough strong power for the IGBT; the main control board is connected with the main control system through optical fibers, receives control instructions of the main control system, translates the control instructions into PWM (pulse-width modulation) trigger signals of four multi-phase IGBTs (insulated gate bipolar transistors) and carries out reliable interlocking, and simultaneously feeds back the state of the low-frequency power unit to the main control system, wherein the reliable interlocking means that short circuit between an upper bridge arm and a lower bridge arm in the same phase and between phases is avoided in the conduction process of the IGBTs; the main control board is connected with the DC/DC power supply module through a twisted pair to obtain a direct-current power supply, and is connected with the IGBT trigger module through the twisted pair to trigger the IGBT after the PWM modulation pulse is amplified by the IGBT trigger module; the input end of the DC/DC power supply module is connected with the positive and negative electrodes (+ E and E) of the laminated busbar through a twisted pair, and power is directly supplied from the inside of the low-frequency power unit without any power supply from the outside.
Further, in order to meet the key performance index, the key parameters of the power device in the main loop are designed in an engineering mode, and the specific method comprises the following steps: rated capacity S of the secondary winding1An engineering design reference value used as a key parameter of a power device in the main loop; the three-phase input end line voltage of the low-frequency power unit is set to be URSPhase current i of the three-phase AFE rectification feedback bridge1=S1/（√3URS) (ii) a The rated output voltage of the low-frequency power unit is marked as U2The rated output current of the single-phase inverter bridge is i2，i2=S1/U2(ii) a Design choice, rated current I of said fast meltinge=（1.5~2）i1The rated voltage is larger than the borne voltage; rated current I of each IGBT in three-phase AFE rectification feedback bridge1e≥（2~3）i1(ii) a Rated current I of each IGBT in single-phase inverter bridge2e≥（2~3）i2(ii) a The engineering design method further comprises: the capacitance value C of each group of the energy storage capacitorsdAccording to the peak voltage E of the low-frequency power unit busbarm（Em=√2URS/2) and a maximum fluctuation amplitude of-5.132%, with a theoretical capacity value of Cd≥2S1/{[1-(100%-5.132%)2]*Em 2*fd} (unit is F, wherein FdIs the pulse frequency, f, of the DC bus voltaged=6 × 50 Hz), the rated voltage is larger than the busbar peak voltage; set the threePWM modulation pulse frequency of phase AFE rectification feedback bridge is fk1The PWM modulation pulse frequency of the single-phase inverter bridge is fk2Preferably, f is selectedk1>fk2Not less than 2 kHz; according to 3-5% of rated capacity S of the secondary winding1The heat radiator is designed as dissipation power and comprises a heat radiation type, a surface area and a volume, and wind speed or flow, and the heat radiator can be an air cooling type, a water cooling type or a heat pipe type; the voltage allowance of the power device IGBT is selected according to at least two times or more of the voltage borne by the power device IGBT; compared with a two-level low-frequency power unit, the low-frequency power unit does not need to be provided with a heavy RCL filter, the engineering design method is relatively simple, and the number of the low-frequency power units required for forming the low-frequency direct-drive high-voltage frequency converter of the elevator is less.
The phase difference between the secondary windings of the rectifier transformer is 0 degrees, the three phases a, b and c of the secondary windings can be connected according to a triangle (D) or a star (Y) under the condition that the online voltage meets the design requirement, the number of the secondary windings is selected and matched according to the voltage level of the lifting motor, for example, the secondary windings are preferably 9 groups (6 kV) or 15 groups (10 kV), and compared with the traditional high-voltage frequency converter, the rectifier transformer is simpler in manufacturing process and lower in cost.
For the low-frequency power unit with the fault, the fault can be degraded and emergently operated at the current time, and the specific method is that the output ends U and V of the low-frequency power unit with the fault and the low-frequency power units at the same positions in other two phases are temporarily short-circuited through a short-circuit cable so as to perform the degradation emergency operation on the low-frequency power unit with the fault; confirming the number of online running stages, namely the number of online running of each phase of low-frequency power units in the main control system again through an external OP panel; in severe cases, only one low-frequency power unit is operated on line in each of the three phases, and the fault current full-load and proper speed reduction emergency operation can be realized, which is particularly important for a hoisting machine for hoisting personnel.
The three-phase AFE rectification feedback bridge and the single-phase inverter bridge in the low-frequency power unit are of a three-level structure, each phase of the three levels is composed of four IGBTs and a neutral point clamping element, an upper bridge arm and a lower bridge arm are respectively provided with two IGBTs which are connected in series and are symmetrically arranged, the neutral point clamping element is a diode or a capacitor or a mixture of the diode and the capacitor, and preferably, the neutral point clamping element is still a diode.
The master control system is provided with a network communication function, besides the communication with a PLC in the lifting electric control system, a plurality of low-frequency direct-drive high-voltage frequency converters of the lifting machine can be in network communication connection and jointly drive the lifting machine with a plurality of sets of stator windings, wherein any one low-frequency direct-drive high-voltage frequency converter of the lifting machine is defined as a master machine, other low-frequency direct-drive high-voltage frequency converters of the lifting machine are defined as slave machines, the master machine has a complete speed closed loop and rotor magnetic field directional vector control function and provides current and frequency given signals and operation instructions for the slave machines, and the slave machines only have a current closed loop function and output three-phase alternating current with the same amplitude and frequency along with the master machine, so that a plurality of sets of stator windings can simultaneously receive the alternating current with; if a small part of the low-frequency direct-drive high-voltage frequency converter of the elevator fails, the failed low-frequency direct-drive high-voltage frequency converter of the elevator temporarily quits for disuse, the rest intact low-frequency direct-drive high-voltage frequency converter of the elevator executes the emergency lifting task of the failed low-frequency direct-drive high-voltage frequency converter by means of the overload capacity of the low-frequency direct-drive high-voltage frequency converter, and the host and the slave can be redefined.
The high-precision encoder is driven by the lifting motor rotor through a coupling mechanism and is used for measuring the rotating speed and the angle of the lifting motor rotor and is used as an important parameter for controlling a speed feedback signal of the low-frequency direct-drive high-voltage frequency converter of the lifting machine and a rotor magnetic field directional vector, the positioning accuracy of the rotor angle directly determines the torque efficiency output by the low-frequency direct-drive high-voltage frequency converter of the lifting machine, the rotor speed is used as a speed closed-loop feedback signal, the precision of the rotor speed directly influences the speed regulation performance of the low-frequency direct-drive high-voltage frequency converter of the lifting machine, and the higher the precision is; the high-precision encoder is preferably in an absolute value mode or an increment mode; therefore, the encoder connecting mechanism is preferably driven by a gear or a friction wheel and is accelerated by a certain multiple, so that the resolution and the precision of rotor angle detection are further improved; the encoder is preferably connected with the connecting mechanism through an elastic coupling or a flexible mechanism, so that the service life of the encoder is prolonged.
The low-frequency power unit has an energy bidirectional transmission function, so that the low-frequency direct-drive high-voltage frequency converter of the hoister has an energy bidirectional transmission function; when the elevator is in a heavy object lifting or positive power deceleration process, the lifting motor is in an electric state, each three-phase AFE rectification feedback bridge rectifies three-phase alternating current with fixed frequency, which is accessed from an input terminal R, S, T, into direct current, after the direct current is leveled by an energy storage capacitor, each single-phase inverter bridge modulates the direct current into single-phase alternating current with adjustable frequency, after the single-phase alternating current is connected in series and superposed, the low-frequency direct-drive high-voltage frequency converter of the elevator outputs the three-phase alternating current with adjustable frequency to supply power to the lifting motor, the energy transmission direction points to the lifting motor from a primary winding of the rectifier transformer, and the lifting motor absorbs electric energy from the frequency converter and; when the elevator is in the process of lowering a weight or decelerating under negative force, the lifting motor is in an electric braking state and is equivalent to a generator, each single-phase inverter bridge rectifies single-phase alternating current with unfixed frequency into direct current, after a direct current bus (+ E, -E) voltage pump rises, each three-phase AFE rectification feedback bridge modulates the direct current into three-phase alternating current with the same frequency and phase as those of a secondary winding of a rectifier transformer, electric energy is fed back to a power grid through the secondary winding of each rectifier transformer and the primary winding, and electric braking is carried out through the feedback, so that the purpose of controlling the speed of the elevator is achieved, and energy is saved.
The low-frequency direct-drive high-voltage frequency converter for the hoister, which is provided by the invention, adopts the technical scheme to realize the stable output frequency range of 0.1 Hz-17.0 Hz, full torque in the whole process and overload multiple not less than two times, meets the requirements of smooth speed regulation and safe operation of constant-torque load of the low-speed direct-connection or built-in hoister, has good static and dynamic performance and small harmonic component and high power factor; compared with the prior art, the rectifier transformer only needs fewer secondary windings, has a relatively simple manufacturing process, needs fewer power units, saves power cables and components, does not need to be provided with a heavy RCL filter, reduces the total volume and weight of equipment, saves equipment investment and operation and maintenance cost, and has remarkable social and economic benefits.
Drawings
FIG. 1 is a schematic diagram of a low-frequency direct-drive high-voltage frequency converter of a hoist according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a low frequency power cell with diode clamping according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of a low frequency power cell with a capacitive clamp according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a low frequency power cell with a diode and capacitor hybrid clamp in accordance with an embodiment of the present invention;
fig. 5 is a low frequency power cell schematic corresponding to fig. 3, 4 and 5.
In the figure: 1. rectifier transformer, 1.1, primary winding, 1.2, secondary winding, 2, low frequency power unit, the content: 2.1, fast melting, 2.2, three-phase AFE rectification feedback bridge, 2.3, voltage-sharing resistor, 2.4, energy storage capacitor, 2.5, single-phase inverter bridge, 2.6, IGBT trigger module, 2.7, main control board, 2.8, DC/DC power module, 3, main control system, 4, high-precision encoder, 5, exciting transformer, 6, exciting rectifier, 7, lifting motor, 8, lifting electric control system.
Detailed Description
Embodiments of the invention are described with reference to figures 1, 2, 3, 4 and 5:
a low-frequency direct-drive high-voltage frequency converter of a hoister is used for driving a low-speed direct-drive or built-in hoister. In fig. 1, the low-frequency direct-drive high-voltage frequency converter of the elevator mainly comprises a rectifier transformer 1, a low-frequency power unit 2, a master control system 3, a high-precision encoder 4, an exciting transformer 5 and a rectifier device 6 thereof; rated capacity S of the rectifier transformer0(kVA) at least according to the rated power P of the hoisting motore(kW) 1.6 times higher, i.e.S0≥1.6PeAnd having a set of primary windings 1.1 and 3 xj (preferably, j =3 or 5) and a set of secondary windings 1.2, the three phases a of said primary windings0、B0And C0The power supply high-voltage switch cabinet is connected with a power supply high-voltage switch cabinet and receives power supply of a power grid, and the voltage class of the power grid is 6kV and 10 kV; thus, the rated capacity S of each set of the secondary windings1=S0(3 x j) and connected with the three-phase input end R, S, T of the low-frequency power unit through power cables, and the three-phase input end R, S, T of the low-frequency power unit is in one-to-one correspondence to provide low-voltage alternating current for the low-frequency power unit; the output ends of the low-frequency power units 2 are marked as U and V and divided into three groups, the number of each group is j (j =3 or 5), the output end U of the first low-frequency power unit 2 in each group is connected together through a bus bar to form a neutral point Q of the low-frequency direct-drive high-voltage frequency converter of the elevator, the output ends V and U of two adjacent low-frequency power units 2 in each group are sequentially connected in series through the bus bar, the output end V of the last low-frequency power unit 2 in each group is respectively connected with three phases of a stator winding of the elevator motor through a power cable to form three-phase A, B, C output of the low-frequency direct-drive high-voltage frequency converter of the elevator; therefore, the number j is also the number of the series connection of each phase of the low-frequency power unit 2 of the low-frequency direct-drive high-voltage frequency converter of the hoist, and is determined by the voltage level of the stator winding of the hoist motor, wherein the voltage level is 6 or 10kV, and j is preferably 3 or 5 correspondingly; the high-precision encoder 4 is driven by a rotor of the lifting motor 7 through a connecting mechanism, and the output end of the high-precision encoder is connected with the input end of the main control system 3 through a shielded cable, and is used for detecting the rotating speed and angle of the rotor of the lifting motor 7 and taking the speed and angle as important signals for the speed closed loop and the rotor magnetic field orientation closed loop vector control of the main control system 3; a PLC analog quantity output port in the lifting electric control system 8 is connected with a signal input interface of the main control system 3 through a shielded cable or is connected in a communication mode to serve as a frequency given signal of the low-frequency direct-drive high-voltage frequency converter of the lifter, and the main control system 3 converts an instruction from the lifting electric control system 8 into a control signal of frequency and moment; the main control system 3 is connected with a main control board 2.7 in the low-frequency power unit 2 through optical fibers, and the low-frequency power isThe unit 2 outputs single-phase alternating current with variable frequency according to the instruction of the main control system 3; if the lifting motor 7 is provided with an excitation winding, as an option, the primary winding of the excitation transformer 5 is connected with a power supply switch through a power cable to obtain an excitation power supply, the secondary winding of the excitation transformer 5 is connected with the three-phase input end of the excitation rectifying device 6 through a three-phase power cable, and the direct-current output end of the excitation rectifying device 6 is connected with the excitation winding of the lifting motor through a two-phase power cable to provide excitation current for the separately excited lifting motor 7.
Further, as shown in fig. 2, the low-frequency power unit 2 mainly comprises a main loop part, an IGBT trigger module 2.6, a main control board 2.7 and a DC/DC power module 2.8; the main loop part comprises a fast melting part 2.1, a three-phase AFE rectification feedback bridge 2.2, two groups of voltage-sharing resistors 2.3, two groups of energy storage capacitors 2.4, a single-phase inverter bridge 2.5 and a radiator 2.9; the three-phase AFE rectification feedback bridge 2.2 and the single-phase inverter bridge 2.5 are both of a three-level structure, each phase of the three-level structure is composed of four IGBTs and a neutral point clamping element, and an upper bridge arm and a lower bridge arm are respectively provided with two IGBTs which are connected in series and are symmetrically arranged; the three-phase AFE rectification feedback bridge 2.2, the power devices IGBT and clamping diode in the single-phase inverter bridge 2.5 and the voltage-sharing resistor 2.3 are arranged according to the principle of uniform heat dissipation and are arranged on the element surface of the radiator 2.9, so that the heat dissipation is facilitated; the fast fuse 2.1 is at least two, and is connected in series between the input end R, S, T of the low-frequency power unit 2 and the three-phase alternating current input end of the three-phase AFE rectification feedback bridge 2.2 through a busbar, so that the main loop of the low-frequency power unit 2 is quickly protected from overcurrent, and meanwhile, the short circuit between an in-phase upper bridge arm and an in-phase lower bridge arm or between phases is prevented; three layers of the laminated busbar respectively connect the three-phase AFE rectification feedback bridge 2.2, the single-phase inverter bridge 2.5, the two groups of energy storage capacitors 2.4 and the anode + E, the zero point 0 and the cathode-E of the voltage-sharing resistor 2.3 together to form three levels (+ E, 0 and E) of the low-frequency power unit; the two groups of energy storage capacitors and voltage-sharing resistors are respectively connected in parallel between busbars (+ E and 0, and 0 and-E), and the energy storage capacitor 2.4 is connected with the voltage-sharing resistor 2.3 in parallel so that the direct-current voltage values borne by the energy storage capacitors 2.4 are basically consistent; the alternating current output end of the single-phase inverter bridge 2.5 is connected to an output terminal through a busbar to form single-phase output ends U and V of the low-frequency power unit 2; the IGBT trigger module 2.6 is connected with the IGBT trigger signal end through a twisted pair to provide a trigger signal with strong enough power for the IGBT; the main control board 2.7 is connected with the main control system 3 through optical fibers, receives control instructions of the main control system 3, translates the control instructions into PWM (pulse-width modulation) trigger signals of four multi-phase IGBTs (insulated gate bipolar translator) and ensures interlocking, and simultaneously feeds back the state of the low-frequency power unit 2 to the main control system 3, wherein the reliable interlocking means that short circuit between an upper bridge arm and a lower bridge arm in the same phase and between phases is avoided in the conduction process of the IGBTs; the main control board 2.7 is connected with the DC/DC power supply module 2.8 through a twisted pair to obtain a direct current power supply, and is connected with the IGBT trigger module through the twisted pair to trigger the IGBT after PWM modulation pulse is amplified by the power of the IGBT trigger module 2.6; the input end of the DC/DC power supply module 2.8 is connected with the positive and negative poles (+ E, -E) of the laminated busbar through a twisted pair, and power is directly supplied from the inside of the low-frequency power unit 2 without any power supply from the outside.
For example, key parameters of the power devices in the main circuit are engineered, and in fig. 1 and 2, assuming that the rated power Pe =2000kW and the rated voltage of the boost motor is 6kV, the number of secondary windings of the rectifier transformer is 9 groups (3 × 3, i.e., j =3 above), so that:
at least selecting the rated capacity of the rectifier transformer to be S0，
S0=1.6*2000=3200kVA；
Accordingly, the rated capacity S of the secondary winding 1.21，
S1=3200/9≈356kVA。
Line voltage U of three-phase input end of low-frequency power unit 2RSPreferably 1.0kV, the rated output voltage of the low-frequency power unit 2 is designated as U2=1.2kV (the actual output voltage may be higher than 1.2 kV), the voltage margin of the power device IGBT is selected at least twice or more than the voltage it withstands, so:
the secondary sideThe phase current of the winding, i.e. the phase current of the three-phase AFE rectifying and feedback bridge 2.2, is i1，
i1=S1/（√3URS）=356/（√3*1.0）≈206A；
The rated output current of the single-phase inverter bridge 2.5 is i2，
i2=S1/U2=356/1.2≈297A。
Therefore, the rated current of the fast melting 2.1 is Ie,
Ie≥（1.5~2）i1= (1.5-2) × 206A = 309-412A, rated current Ie =355A of the fast melting 2.1 is selected, and rated voltage is 1250V: (2-2) =>1.0kV, and the voltage withstand requirement is met);
the rated current of each IGBT in the three-phase AFE rectification feedback bridge 2.2 is I1e，
I1e≥（2~3）i1Selecting rated current I of IGBT in three-phase AFE rectification feedback bridge 2.2 according to = 2-3 × 206A = 412-618A1e=450A (current margin of about 2.2 times, meeting the requirement of more than 2 times), rated voltage 1700V;
rated current of each IGBT in the single-phase inverter bridge 2.5 is I2e，
I2e≥（2~3）i2Selecting rated current I of IGBT (insulated Gate Bipolar transistor) in the single-phase inverter bridge, wherein = 2-3: 297A = 594-891A2e=650A (current margin of about 2.2 times, meeting the requirement of more than 2 times), rated voltage 1700V;
in the above, the voltage margin of each IGBT in the three-phase AFE rectification feedback bridge 2.2 and the single-phase inverter bridge 2.5 is 2 × 1.7kV/(√ 2U)RS) About 2.4 times, desirably more than 2 times.
The engineering design method further comprises: the capacitance value C of each group of the energy storage capacitors is 2.4dAccording to the peak voltage E of the bus bar of the low-frequency power unit 2m（Em=√2U RS2 ≈ 707V) and the maximum fluctuation amplitude is-5.132%, and the theoretical capacity value is Cd≥2S1/{[1-(100%-5.132%)2]*Em 2*fd} (unit is F, wherein FdIs the pulse frequency, f, of the DC bus voltaged=6 × 50Hz =300 Hz), so:
Cd≥2*356*103*106/{0.1*7072300} is approximately equal to 47481uF, therefore, two capacitors with rated capacitance/voltage of 10000uF/400V are selected to be connected in series after being connected in parallel, each capacitor is 10, and thus, the capacitance C of one group of the energy storage capacitorsdIn fact 10 x 10000uF/2=50000uF, the total rated voltage is 800V, which is larger than the peak voltage Em=707V, as required; therefore, in this example, 4 capacitors with a rated capacitance/voltage of 10000uF/400V are needed to form two sets of energy storage capacitors according to the above combination, and the two sets of energy storage capacitors are respectively connected in parallel between the bus (+ E and 0, and 0 and-E), and each capacitor is connected in parallel with the voltage equalizing resistor.
Preferably, the PWM modulation pulse frequency of the three-phase AFE rectification feedback bridge is selected to be fk1=2.4kHz, the PWM modulation pulse frequency of the single-phase inverter bridge is fk2=2.0kHz, in accordance with fk1>fk2The requirement of not less than 2 kHz.
According to 3-5% of rated capacity S of the secondary winding1Namely, about 10 to 18kW is designed as the dissipation power of the low frequency power unit in this embodiment, the heat sink includes a heat dissipation type, a surface area and a volume, and a wind speed or a flow rate, and the heat sink may be an air cooling type, a water cooling type or a heat pipe type.
Description of the drawings: the relationship between the unit conversion in the engineering design described above involves: capacity 1kVA =103VA, frequency 1kHz =103Hz, voltage 1kV =1000V, capacitance 1F =106uF。
In the above embodiment, the rated output voltage of the secondary winding 1.2 is preferably 1.0kV, the dc bus (+ E, -E) voltage of the low-frequency power unit 2 is stabilized at the peak voltage 1414 (1000 × V2) V by PWM (pulse width modulation), the rated output voltage of the low-frequency power unit 2 is preferably calibrated to a single-phase 1.2kV (the actual output may be greater than ac1.2 kV), and the various voltage levels of the low-frequency direct-drive high-voltage frequency converter of the hoist driving the hoist motor 7 are listed in table 1 according to the different number of the low-frequency power units 2 connected in series per phase.
As can be seen from table 1, the number of low frequency power units required in this embodiment is smaller than that of the conventional high voltage inverter, and the boost motor has a rated voltage level of 6kV, which saves at least 6 (3 × 2) stages, and has a rated voltage level of 10kV, which saves at least 9 (3 × 3) stages.
In the above embodiment, the step-up motor voltage level is assumed to be 6kV, and the three groups of the low-frequency power units are respectively composed of group a (group a)1、A2And A3) Group B (B)1、B2And B3) And group C (C)1、C2And C3) Composition, assume A2When a fault occurs, the fault can be reduced to 2-level emergency operation, and the specific method is that the low-frequency power units A with the faults are respectively connected with the short-circuit cables2And the low-frequency power units B in the same positions in the other two phases2And C2The output ends U and V are short-circuited temporarily, and the series (2 levels) of online operation is confirmed again in the main control system 3 through an OP panel and the like, and the fault can operate at two-thirds rated speed when the fault occurs; in severe cases, as A in the low-frequency power unit 22And B3When faults occur simultaneously, the low-frequency power units A are respectively connected through short-circuit cables2、A3And the low-frequency power units B in the same positions in the other two phases2、B3And C2、C3The output ends U and V are short-circuited temporarily, the number of stages (1 stage) of online operation is confirmed, and the fault can operate at a rated speed of one third at the time; when the fault happens, full-load emergency operation is realized, which is particularly important for a hoisting machine for hoisting personnel.
The three-phase AFE rectification feedback bridge 2.2 and the single-phase inverter bridge 2.5 in the low-frequency power unit 2 are both of a three-level structure, each phase of the three-level structure is composed of four IGBTs and a neutral point clamping element, an upper bridge arm and a lower bridge arm are respectively provided with two IGBTs which are connected in series and are symmetrically arranged, and the neutral point clamping element is a diode, as shown in figure 2; alternatively, the neutral point clamping element is a capacitor, as shown in fig. 3; alternatively, the neutral point clamping element is of a diode and capacitor hybrid type, as shown in fig. 4; preferably, the neutral point clamping elements are still diodes.
In fig. 1, the hoisting motor 7 is a set of stator windings, and if there are several sets of stator windings, several low-frequency direct-drive high-voltage frequency converters of the hoisting machine are required to implement a one-to-one driving scheme; the master control system 3 is provided with a network communication function, so that the lifting electric control system 8 and a plurality of the lifting machine low-frequency direct-drive high-voltage frequency converters can be in network communication connection to jointly drive a lifting motor with a plurality of sets of stator windings, wherein any one lifting machine low-frequency direct-drive high-voltage frequency converter is defined as a host, other lifting machine low-frequency direct-drive high-voltage frequency converters are defined as slaves, the host has a complete speed closed loop and rotor magnetic field directional vector control function and provides current and frequency given signals and operation instructions for the slaves, the slaves only have a current closed loop function and output three-phase alternating current with the same amplitude and frequency along with the host, and a plurality of sets of the stator windings are ensured to simultaneously receive the basically consistent alternating current; if a small part of the low-frequency direct-drive high-voltage frequency converter of the elevator fails, the failed low-frequency direct-drive high-voltage frequency converter of the elevator temporarily quits for disuse, the rest intact low-frequency direct-drive high-voltage frequency converter of the elevator executes the emergency lifting task of the failed low-frequency direct-drive high-voltage frequency converter by means of the overload capacity of the low-frequency direct-drive high-voltage frequency converter, and the host and the slave can be redefined.
The high-precision encoder 4 is driven by the rotor of the lifting motor 7 through a coupling mechanism, is used for measuring the rotating speed and the angle of the rotor of the lifting motor 7 and is used as an important parameter for controlling a speed feedback signal of the low-frequency direct-drive high-voltage frequency converter of the lifting machine and a rotor magnetic field orientation vector, the positioning accuracy of the rotor angle directly determines the torque efficiency output by the low-frequency direct-drive high-voltage frequency converter of the lifting machine, the rotor speed is used as a speed closed-loop feedback signal, the precision directly influences the speed regulation performance of the low-frequency direct-drive high-voltage frequency converter of the lifting machine, and the higher the precision is; the high-precision encoder is preferably in an absolute value mode or an increment mode; therefore, the encoder connecting mechanism is preferably driven by a gear or a friction wheel and is accelerated by a certain multiple, so that the resolution and the precision of rotor angle detection are further improved; the encoder is preferably connected with the connecting mechanism through an elastic coupling or a flexible mechanism, so that the service life of the encoder is prolonged.
The low-frequency power unit 2 has an energy bidirectional transmission function, so that the low-frequency direct-drive high-voltage frequency converter of the hoister has an energy bidirectional transmission function; when the elevator is in a heavy object lifting or positive power deceleration process, the lifting motor 7 is in an electric state, each three-phase AFE rectification feedback bridge 2.2 rectifies three-phase alternating current with fixed frequency, which is accessed from an input terminal R, S, T, into direct current, each single-phase inverter bridge 2.5 rectifies the direct current into single-phase alternating current with adjustable frequency after being leveled by an energy storage capacitor 2.4, the single-phase inverter bridges 2.5 modulate the direct current into single-phase alternating current with adjustable frequency, after the single-phase alternating current is serially connected and superposed, the low-frequency direct-drive high-voltage frequency converter of the elevator outputs the three-phase alternating current with adjustable frequency to supply power to the lifting motor 7, the primary side energy transmission direction points to the lifting motor 7 from a winding 1; when the elevator is in the process of lowering a weight or decelerating under negative force, the lifting motor 7 is in an electric braking state and is equivalent to a generator, each single-phase inverter bridge 2.5 rectifies single-phase alternating current with unfixed frequency into direct current, after a direct current bus (+ E, -E) voltage pump rises, each three-phase AFE rectification feedback bridge 2.2 modulates the direct current into three-phase alternating current with the same frequency and phase as those of the rectifier transformer secondary winding 1.2, electric energy is fed back to a power grid through each secondary winding 1.2 of the rectifier transformer and the primary winding 1.1, and electric braking is performed through feedback, so that the purpose of controlling the speed of the elevator is achieved, and energy is saved.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited thereto, and any equivalent changes based on the technical solutions of the present invention are within the protection scope of the present invention.
Claims (10)
1. The utility model provides a high-voltage inverter is directly driven to lifting machine low frequency which characterized in that: the low-frequency direct-drive high-voltage frequency converter of the elevator comprises a rectifier transformer, a low-frequency power unit, a master control system and a high-precision encoder; rated capacity S of the rectifier transformer0At least according to the rated power P of the hoisting motore1.6 times of selection, i.e. S0≥1.6Pe(ii) a The rectifier transformer is provided with a group of primary windings and 3 xj groups of secondary windings; the primary winding is connected with a power supply high-voltage switch cabinet and receives power supply of a power grid; rated capacity S of each set of secondary windings1=S0(3 x j) are connected with the three-phase input ends R, S, T of the low-frequency power units through power cables in a one-to-one correspondence mode, and low-voltage alternating current is supplied to the low-frequency power units; the output ends of the low-frequency power units are marked as U and V and divided into three groups, the number of each group is also j, the output end U of the first low-frequency power unit in each group is connected together through a bus bar to form a neutral point of the low-frequency direct-drive high-voltage frequency converter of the elevator, the output ends V and U of two adjacent low-frequency power units in each group are sequentially connected in series through the bus bar, and the output end V of the last low-frequency power unit in each group is respectively connected with three phases of a stator winding of the elevator motor through a power cable to form three-phase output of the low-frequency direct-drive high-voltage frequency converter; the high-precision encoder is driven by a rotor of the lifting motor through a connecting mechanism, and the output end of the high-precision encoder is connected with the input end of the main control system through a shielded cable and used for detecting the rotating speed and angle of the rotor of the lifting motor to serve as important signals for the vector control of a speed closed loop and a rotor magnetic field orientation closed loop of the main control system; the PLC analog output port in the hoisting electric control system is connected with the signal input interface of the master control system through a shielded cable or is connected in a communication mode to serve as a frequency given signal of the low-frequency direct-drive high-voltage frequency converter of the hoisting machine, and the master control system converts an instruction from the hoisting electric control system into a frequencyRate and torque control signals; the main control system is connected with a main control board in the low-frequency power unit through optical fibers, and the low-frequency power unit outputs single-phase alternating current with variable frequency according to instructions of the main control system.
2. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the low-frequency direct-drive high-voltage frequency converter of the hoister also comprises an exciting transformer and a rectifying device; the primary winding of the excitation transformer is connected with a power supply switch through a power cable to obtain an excitation power supply, the secondary winding of the excitation transformer is connected with the three-phase input end of the excitation rectifying device through a three-phase power cable, and the direct current output end of the excitation rectifying device is connected with the excitation winding of the lifting motor through a two-phase power cable to provide excitation current for the separately excited lifting motor.
3. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the number j of the j groups of secondary windings is 3 or 5.
4. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the number of stages of each phase of the low-frequency direct-drive high-voltage frequency converter of the elevator, which is connected in series with the low-frequency power unit, is determined by the voltage level of a stator winding of the elevator motor, and the voltage level is 6 or 10 kV.
5. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the phase difference between the secondary windings of the rectifier transformer is 0°And under the condition that the line voltage meets the design requirement, connecting the three phases a, b and c of the secondary winding according to a triangle or star shape.
6. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the stable output frequency range of the low-frequency direct-drive high-voltage frequency converter of the hoister is 0.1 Hz-17.0 Hz.
7. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the low-frequency power unit is a four-quadrant three-level low-frequency power unit; the low-frequency power unit mainly comprises a main loop part, an IGBT trigger module, a main control board and a DC/DC power module; the main loop part comprises a fast melting part, a three-phase AFE rectification feedback bridge, two groups of energy storage capacitors, a voltage-sharing resistor, a single-phase inverter bridge and a radiator; the three-phase AFE rectification feedback bridge and the single-phase inverter bridge are both of three-level structures, each phase of the three-level structure is composed of four IGBTs and a neutral point clamping element, an upper bridge arm and a lower bridge arm are respectively provided with two IGBTs which are connected in series and are symmetrically arranged, and the neutral point clamping element is a diode or a capacitor or a diode and capacitor mixed three types.
8. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 7, wherein: the neutral point clamping element is preferably a diode.
9. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the master control system is provided with a network communication function, a plurality of low-frequency direct-drive high-voltage frequency converters of the hoister can be connected in a network communication mode except for the communication with the PLC in the hoisting electric control system, one of the low-frequency direct-drive high-voltage frequency converters of the hoister is defined as a master machine under any condition, and the other low-frequency direct-drive high-voltage frequency converters of the hoister are defined as slave machines.
10. The low-frequency direct-drive high-voltage frequency converter of the elevator as claimed in claim 1, wherein: the high-precision encoder is driven by the rotor of the lifting motor through a connecting mechanism, and the connecting mechanism of the encoder is preferably driven by a gear or a friction wheel and is accelerated by a certain multiple; the encoder is preferably connected with the connecting mechanism through an elastic coupling or a flexible mechanism.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112698671A (en) * | 2020-11-23 | 2021-04-23 | 铜陵国星化工有限责任公司 | Finished product monitoring method, and automatic additive adding method and system |
| CN114371661A (en) * | 2021-12-02 | 2022-04-19 | 太原重工股份有限公司 | Emergency operation control system of dry quenching hoister |
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| CN108512438A (en) * | 2018-06-14 | 2018-09-07 | 洛阳源创电气有限公司 | A kind of mine hoist low frequency directly drives medium-high voltage frequency converter |
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| CN103036449A (en) * | 2011-09-30 | 2013-04-10 | 苏州汇川技术有限公司 | Four-quadrant three-level power unit and high-voltage inverter |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112698671A (en) * | 2020-11-23 | 2021-04-23 | 铜陵国星化工有限责任公司 | Finished product monitoring method, and automatic additive adding method and system |
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| CN114371661A (en) * | 2021-12-02 | 2022-04-19 | 太原重工股份有限公司 | Emergency operation control system of dry quenching hoister |
| CN114371661B (en) * | 2021-12-02 | 2023-07-21 | 太原重工股份有限公司 | Emergency operation control system of coke dry quenching hoister |
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