CN202334402U - All-solid-state controller for star soft handover of motor - Google Patents

Abstract

The utility model discloses an all-solid-state controller for star soft handover of a motor, belonging to the technical field of star soft handover of motors. The all-solid-state controller comprises a switching element, a data acquisition unit, a microcomputer control unit, a driving unit, a triggering unit, a secondary loop other element and a connecting wire, wherein the data acquisition unit is directly connected with the microcomputer control unit, and is used for supplying an input signal to the microcomputer control unit; the microcomputer control unit is connected with the driving unit and the triggering unit respectively, and is used for transmitting respective output signals to the driving unit and the triggering unit respectively; the driving unit is connected with a contactor in the switching element, and is used for driving the contactor to be switched on or switched off; the triggering unit is connected with a thyristor in the switching element, and is used for performing star soft handover control; and the secondary loop other element comprises devices such as a transformer and a switching power supply, and is taken as a direct-current power supply for a part of the microcomputer control unit, the triggering unit and the driving unit. The all-solid-state controller has the advantages that: impact-free star soft handover is realized for an energy-saving motor which requires frequent star handover, and the problem of current impact during star handover of the conventional star starting device is solved.

Description

An all-solid-state controller for motor star angle soft switching

technical field

The utility model belongs to the technical field of motor star-angle switching, in particular to an all-solid-state controller for motor star-angle soft switching.

Background technique

Motor star-delta switching is often used for motor winding star-delta switching to save energy and motor star-delta step-down starting.

Motor winding star angle switching is one of the common means of motor energy saving. There are two common types of traditional motor star angle switching devices:

The first one utilizes the single-chip computer to control the contactor switch to realize star-delta switching. Switching is not fast enough, and the contactor switch can also cause overvoltage due to the presence of arcing when it opens.

The second type adopts thyristor non-contact switch to replace contactor, which ensures the rapidity of star-delta switching. However, since the thyristor adopts the trigger strategy of three-phase simultaneous conduction, a large inrush current will still be generated when switching. When the load rate of the motor changes frequently, the energy-saving efficiency of star-delta switching will be reduced.

When the motor is directly started, a large inrush current will be generated, which will not only cause heat damage to the motor, but also cause severe fluctuations in the voltage of the power supply grid. The traditional star-delta step-down starting cannot continuously adjust the starting voltage of the motor, and a large current impact will still be generated when the star connection changes to delta connection during the starting process.

The all-solid-state controller for motor star angle soft switching is to control two sets of thyristor switches through DSP microprocessor to quickly implement star angle soft switching, eliminate the current and torque impact during switching, and make frequent star angle switching energy saving and star angle The starting can be realized, and it has more rapid and flexible characteristics than the semi-solid-state star-delta soft-switching controller.

Contents of the invention

The purpose of the utility model is to provide an all-solid-state controller for motor star angle soft switching, which overcomes the deficiencies of the prior art, and realizes star angle soft starting of the motor while realizing energy saving by star angle soft switching of motor windings.

The utility model comprises a switch element, a data acquisition unit, a microcomputer control unit, a drive unit, a trigger unit, other components of a secondary circuit and wiring. The data acquisition unit is directly connected to the microcomputer control unit, and the input signal is provided to the microcomputer control unit; the microcomputer control unit is connected to the drive unit and the trigger unit respectively, and the respective output signals are sent to them respectively; the drive unit is connected to the contactor in the switching element , to drive it to close or open; the trigger unit is connected to the thyristor in the switch element to implement star-delta soft switching control; other components of the secondary circuit include transformers and switching power supplies, which are part of the microcomputer control unit, trigger unit and drive unit The DC power supply, plus some wiring for the drive unit interlock circuit.

The switching element includes two sets (six pairs) of anti-parallel thyristors and two contactors, and also includes an air circuit breaker to protect the circuit. Among them, the anti-parallel thyristor is the main switching element of the utility model, which can be replaced by bidirectional thyristor or other power electronic switches. Two sets of thyristor switches are respectively used for star connection and angle connection of motor windings, so it is called all solid state.

Among them, three pairs of anti-parallel thyristors SCR1 and contactor KM1 are connected in series to form a loop between the three-phase power supply and the motor winding, forming a delta connection of the motor; the other three pairs of anti-parallel thyristors SCR2 and contactor KM2 are connected in series to form a circuit between the three-phase power supply and the motor winding. A circuit is formed between the motor windings to form a star connection of the motor; an air circuit breaker is connected between the three-phase power supply and the motor stator winding to protect the main circuit.

The data acquisition unit is composed of two voltage transformers and a current transformer. The two input terminals of one of the voltage transformers are respectively connected in parallel with phase A and phase B of the power supply in the main circuit to detect the three-phase line voltage U _AB of the power supply. The two input ends of another voltage transformer are respectively connected in parallel with phase B and phase C of the power supply in the main circuit to detect the three-phase line voltage U _BC of the power supply. The output end of the voltage transformer is connected to the microcomputer control unit through the voltage conditioning circuit. The current transformer collects three-phase phase current signals from the main circuit, and the output terminal is connected to the microcomputer control unit through the conditioning circuit.

The microcomputer control unit includes a DSP chip and an AD conversion chip. Among them DSP adopts TMS320F2812 of TI Company. The AD conversion chip uses 2 pieces of AD7656, which can perform digital-to-analog conversion on the signals of 12 channels at the same time. After the signal detected by the detection unit is input to the DSP, after entering the AD conversion chip to complete the digital-to-analog conversion, the DSP will analyze and process the digital signal, and then output the signal to realize the control of the switch unit.

The drive unit is used to drive the contactor, adopts the secondary drive mode, uses the output of DSP to drive the relay, and then drives the contactor through the relay, and uses optocoupler isolation to completely isolate the input and output signals electrically.

The trigger unit is used to trigger the thyristor. The pulse train trigger is adopted. The control signal and the pulse train signal output by the DSP pass through the gate circuit, and after the power is amplified by the MOSFET, they are sent to the pulse transformer, and the output signal controls the thyristor to trigger.

In order to realize the control of the contactor and the thyristor, the output of the microcomputer control unit is connected with the drive unit and the trigger unit. DSP analyzes and processes the signal collected by the acquisition unit, and judges the load condition of the motor, so as to make a judgment on whether to perform star angle soft switching.

When the motor is under light load, the motor is switched from delta connection to star connection. At this time, DSP first controls SCR1 to turn off, then disconnects KM1, and finally triggers SCR2 according to the star connection soft switching method, and controls the motor to switch to star connection without impact. .

When the motor is under heavy load, the motor is switched from star connection to delta connection. At this time, DSP first controls SCR2 to turn off, then turns off KM2, and finally triggers SCR1 according to the soft switching method of delta connection, and controls the motor to switch to delta connection without impact. .

Other components of the secondary circuit include 380/220 single-phase transformers, relays and switching power supplies for secondary control of contactors. The single-phase transformer is connected to any two-phase line voltage of the three-phase power supply, the output 220V AC voltage is connected to the input terminal of the switching power supply, and the switching power supply outputs 5V and 12V DC voltage, which is connected to the microcomputer control unit, trigger unit and drive relay as their power supply. The normally open contact of the relay that realizes the secondary control of the contactor cooperates with the normally closed contact of the contactor to realize the interlock of KM1 and KM2.

Compared with the prior art, the beneficial effect of the utility model is: the utility model utilizes six pairs of non-contact and arc-free silicon controlled rectifier switches to realize the flux linkage of the motor between the star connection and the delta connection of the three-phase winding through a series of trigger control It can transition smoothly, thereby suppressing the current and torque impact during star-delta switching.

When the controller is in the energy-saving mode of star-delta switching of motor windings, even if the motor load changes frequently, the energy-saving efficiency of star-delta switching will not be reduced. When the controller is in the star-delta starting mode of the motor, the sudden change of the voltage during star-delta switching will not cause the increase of the starting current of the motor.

Description of drawings

Fig. 1 is a topological structure diagram of the main circuit in which U1-W2, V1-U2, and W1-V2 of the utility model form corner connections.

Fig. 2 is a topological structure diagram of the main circuit in which U1-V2, V1-W2, and W1-U2 form corner connections of the utility model.

Fig. 3 is a secondary circuit diagram of the utility model.

Fig. 4 is a schematic diagram of the control of the microcomputer unit of the utility model.

Detailed ways

The utility model comprises a switch element, a data acquisition unit, a microcomputer control unit, a drive unit, a trigger unit, other components of a secondary circuit and wiring. The data acquisition unit is directly connected to the microcomputer control unit, and the input signal is provided to the microcomputer control unit; the microcomputer control unit is connected to the drive unit and the trigger unit respectively, and the respective output signals are sent to them respectively; the drive unit is connected to the contactor in the switching element , to drive it to close or open; the trigger unit is connected to the thyristor in the switch element to implement star-delta soft switching control; other components of the secondary circuit include transformers and switching power supplies, which are part of the microcomputer control unit, trigger unit and drive unit The DC power supply, plus some wiring for the drive unit interlock circuit.

Below in conjunction with accompanying drawing and specific embodiment the utility model is described in further detail:

Fig. 1 is the topological structure diagram of the main circuit of the utility model in which U1-W2, V1-U2, and W1-V2 of the utility model form an angle connection. Among them, SCR1 and SCR2 are anti-parallel thyristors, KM1 and KM2 are contactors, U1-U2, V1-V2, W1-W2 are three-phase windings of the motor, QF is an air circuit breaker, L1, L2 and L3 are three-phase power supplies line, N is the ground line. The air circuit breaker QF is connected between the three-phase power supply and the motor winding, and the upper ports U1, V1, W1 of the motor winding are connected to the thyristor SCR1, and the thyristor SCR1 and the contactor KM1 are connected in series to W2, U2 of the motor winding , V2 terminal. Connect the thyristor SCR2 at the lower end of the motor winding U2, V2, W2, and connect the thyristor SCR2 and the contactor KM2 in series.

Fig. 2 is a topological structure diagram of the main circuit in which U1-V2, V1-W2, and W1-U2 form an angle connection of the utility model. Among them, SCR1 and SCR2 are anti-parallel thyristors, KM1 and KM2 are contactors, U1-U2, V1-V2, W1-W2 are three-phase windings of the motor, QF is an air circuit breaker, L1, L2 and L3 are three-phase power supplies line, N is the ground line. The air circuit breaker QF is connected between the three-phase power supply and the motor winding, and the upper ports U1, V1, W1 of the motor winding are connected to the thyristor SCR1, and the thyristor SCR1 and the contactor KM1 are connected in series to V2, W2 of the motor winding , U2 terminal. Connect the thyristor SCR2 at the lower end of the motor winding U2, V2, W2, and connect the thyristor SCR2 and the contactor KM2 in series.

Fig. 3 is a control secondary circuit diagram of the utility model. When the DSP sends a low-level signal to the drive circuit of KM1, the coil of the relay KA1 is energized, the normally open contact KA1-O is closed, the KM1 coil is closed, the normally closed contact KM1-C of KM1 is disconnected, and the KM2 coil is powered off , to ensure that KM1 is closed while KM2 is in an off state. Similarly, when KM2 is closed, KM1 is turned off. Since KM1 and SCR1 are connected in series and KM2 and SCR2 are connected in series, the interlock between KM1 and KM2 realizes the interlock between SCR1 and SCR2. When the motor performs star-delta soft switching, it will not be damaged due to false triggering of anti-parallel thyristors. lead to a short circuit failure. In addition, a 380/220 transformer is used in the secondary circuit to supply power to the switching power supply, and then to supply power to the DSP.

Fig. 4 is a schematic diagram of the microcomputer unit control of the utility model. The voltage transformer and current transformer in the data acquisition unit detect the voltage and current of the power supply side. The collected signal is adjusted to the DC voltage range -10V-+10V acceptable to the AD7656 through the conditioning circuit, and then the AD7656 converts the collected voltage and current analog quantities into digital quantities and transmits them to the DSP. The DSP analyzes and calculates the input digital signal, and obtains the motor load rate β and star-angle switching critical load rate βc, and sends signals to the drive unit and trigger unit according to the magnitude of β and βc. The signal from the trigger unit is sent to the pulse transformer after passing through the photoelectric isolation and the signal from the pulse generator through the gate circuit, and the triggering of SCR1 and SCR2 is realized by controlling the anode and cathode of the thyristor. The signal of the drive unit is photoelectrically isolated, and the contactors KM1 and KM2 are closed and closed by driving the coil of the relay.

The specific implementation strategy of the motor star angle soft start of the utility model is as follows: the DSP is powered on, and the motor begins to start. The contactor KM2 is closed, and the thyristor SCR2 is triggered according to the star connection soft switching control strategy. At this time, the motor is in the star connection operation state. When the motor speed reaches the set value, the thyristor SCR2 stops triggering, the contactor KM2 is turned off, the contactor KM1 is closed, and then SCR1 is triggered according to the delta connection soft switching control strategy, and the motor completes the star delta soft start.

The utility model can not only realize star-angle soft start when the motor is started, but also realize energy-saving star-angle soft switching of windings during the operation of the motor.

The specific implementation strategy of the electric motor of the present invention to realize star-angle soft switching is as follows: When the motor is in the state of star-connected operation, the DSP uses the detected signal to calculate and analyze the motor load rate β and star-angle switching critical load rate β _c , if β<β _c , the motor keeps running in star connection. If β>β _c , the motor will perform soft switching from star connection to delta connection. The specific soft switching process is as follows: the SCR SCR2 stops triggering first, then the contactor KM2 is turned off, and the motor is disconnected from the star-connected running state; after that, the contactor KM1 is closed, and the SCR SCR1 is triggered according to the star angle soft switching strategy. At this time, the motor completes the soft switching from star connection to delta connection, and the motor is in the delta connection operation state. At this time, if β>β _c , the motor will keep operating in delta connection; if β<β _c , the motor will perform soft switching to star connection. The specific soft switching process is as follows: the SCR SCR1 stops triggering first, then the contactor KM1 is turned off, and the motor is disconnected from the delta connection running state; after that, the contactor KM2 is closed, and the SCR SCR2 is triggered according to the star angle soft switching strategy, At this time, the motor completes the soft switching from delta connection to star connection, and the motor is in star connection operation state. Repeat the above steps to realize the frequent star-angle soft switching of the motor.

The utility model well suppresses the current impact when the motor starts star-angle softly when the motor star-angle starts. After the motor starts, according to the load of the motor, the star-delta soft switching control of the motor winding is realized by means of DSP, which can also reduce the inrush current during switching and improve the energy-saving efficiency of the motor with frequent star-delta switching.

Claims (4)

1. A kind of all-solid-state controller of electric motor star-angle soft switching, it is characterized in that, comprises switching element, data acquisition unit, microcomputer control unit, drive unit, trigger unit, other elements of secondary circuit; Data acquisition unit and microcomputer control unit Directly connected, the microcomputer control unit is connected to the drive unit and the trigger unit respectively, the drive unit is connected to the contactor in the switch element, the trigger unit is connected to the thyristor in the switch element, and other components of the secondary circuit include a transformer and a switching power supply, as a microcomputer control DC power supply for the unit, trigger unit and part of the drive unit; The switching elements include two sets of six pairs of anti-parallel thyristors, two contactors, and an air circuit breaker, and the two sets of thyristor switches are respectively used for star connection and angle connection of motor windings; Among them, three pairs of anti-parallel thyristors SCR1 and contactor KM1 are connected in series to form a loop between the three-phase power supply and the motor winding, forming a delta connection of the motor; the other three pairs of anti-parallel thyristors SCR2 and contactor KM2 are connected in series to form a circuit between the three-phase power supply and the motor winding. A circuit is formed between the motor windings to form a star connection of the motor; an air circuit breaker is connected between the three-phase power supply and the motor stator windings. 2. the all-solid-state controller of motor star angle soft switching according to claim 1 is characterized in that, described data acquisition unit is made of two voltage transformers and a current transformer; Two of wherein a voltage transformer One input terminal is connected in parallel with phase A and phase B of the power supply in the main circuit, and the two input terminals of the other voltage transformer are connected in parallel with phase B and phase C of the power supply in the main circuit respectively, and the output terminal of the voltage transformer is voltage regulated The circuit is connected to the microcomputer control unit. 3. the all-solid-state controller of motor star angle soft switching according to claim 1, is characterized in that, described microcomputer control unit has included DSP chip and AD conversion chip; Wherein DSP TMS320F2812, AD conversion chip adopts 2 slices of AD7656 . 4. The all-solid-state controller for motor star-angle soft switching according to claim 1, characterized in that the output of the microcomputer control unit is connected with the drive unit and the trigger unit.

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