CN211859998U

CN211859998U - Device for soft starting, soft shutoff and current-limiting operation of direct current motor

Info

Publication number: CN211859998U
Application number: CN202020539883.4U
Authority: CN
Inventors: 焦艳萍; 李国利
Original assignee: Individual
Current assignee: Individual
Priority date: 2020-04-14
Filing date: 2020-04-14
Publication date: 2020-11-03
Anticipated expiration: 2030-04-14

Abstract

The utility model discloses a device of soft start, soft shutoff of direct current motor and current-limiting operation, keep apart drive unit, open and stop switch, auxiliary relay unit including direct current motor, reverse freewheel diode, IGBT switch tube, motor current detection resistance, three direct current switch power of group, motor current detecting element, the soft shutoff of starting of motor and current-limiting operation the control unit, level. The utility model discloses, through the change condition of the homophase input end voltage that detects the soft shutoff of motor starting and current-limiting operation control unit, export a suitable drive level, drive unit's drive is kept apart through the level, drive the on-state of IGBT switch tube to reach the purpose of direct current motor soft start, soft shutoff and current-limiting operation, avoided whole direct current motor transmission system to bear big electromagnetism and mechanical shock, increased direct current motor transmission system's reliability.

Description

Device for soft starting, soft shutoff and current-limiting operation of direct current motor

Technical Field

The utility model relates to an electron power conversion technology field, in particular to device of soft start, soft shutoff and current-limiting operation of direct current motor.

Background

In the conventional dc motor drive circuit, when the full-voltage start is performed, the inrush current is about 20 times of the rated current. Such a large impact current has a large impact on the lines of the dc power supply circuit, the contactors, the battery pack (or the dc power supply device) of the dc panel, the armature winding of the dc motor, the rotor of the dc motor, and the like, and in addition, has a large mechanical impact on the mechanical load part dragged by the dc motor, and the current may deform the end of the winding of the motor and heat the armature winding seriously, thereby damaging the winding of the motor and the commutation device in advance. Meanwhile, when the direct current motor is turned off, because the full voltage is directly turned off, for the motor winding, the forced turn-off can generate high back electromotive force at two ends of the armature winding, and the back electromotive force can far exceed the power supply voltage and is multiple times, so that the armature winding of the direct current motor can be damaged. The improved DC motor starting circuit is started by using series resistor to reduce voltage, and the starting current is limited in a reasonable range due to the current limiting of the resistor. Generally, in order to limit the current within a reasonable range, a method of connecting multiple resistors in series and cutting off the resistors step by step is mostly adopted to perform current-limiting soft start. The method has the following advantages though: the current limiting resistor is connected in series to reduce the loop current of the motor, so that the direct current motor has the advantages of greatly reducing the impact on mechanical loads of a direct current motor, a power supply loop and dragging. However, the method still has the defects of complex control circuit, arc discharge, mechanical and electromagnetic impact and the like when the direct current contactor is switched on and switched off. In order to enable the current to slowly rise when the direct current motor is started, the current is not over-limited when the direct current motor is operated, and the current slowly falls when the direct current motor is turned off, so that the aim of almost having no impact on a direct current power supply loop, the direct current motor and mechanical loads carried by the direct current motor is fulfilled.

Disclosure of Invention

The utility model discloses the problem that will solve mainly realizes through following technical scheme.

The utility model discloses an in an example, a device of soft start, soft shutoff of direct current motor and current-limiting operation, include direct current motor, reverse freewheel diode, IGBT switch tube, motor current detection resistance, three DC switch power supplies of group, motor current detecting element, the soft shutoff of motor start and current-limiting operation control unit, level isolation drive unit, open and stop switch, auxiliary relay unit. One end of the direct current motor is connected to a DC + pole of a power supply end, the other end of the direct current motor is connected to a drain electrode of an IGBT (insulated gate bipolar transistor) switching tube, the reverse freewheeling diode is reversely connected in parallel with the direct current motor, the drain electrode of the IGBT switching tube is connected to the other end of the direct current motor, a gate electrode of the IGBT switching tube is connected to the output end of the level isolation driving unit, a source electrode of the IGBT switching tube is connected to one end of a motor current detection resistor, and the other end of the motor current detection. The three groups of switch power supplies respectively provide power for the level isolation driving unit, the motor current detection unit, the motor soft start soft turn-off and current limiting operation control unit, the start-stop switch and the intermediate relay unit. The motor current detection unit is used for detecting the motor current and amplifying a voltage signal generated by the current, the motor soft start soft turn-off and current limiting operation control unit is used for controlling the current of the direct current motor in three different stages of starting, stable operation and turn-off, and the level isolation driving unit is used for completing isolation driving of the IGBT switching tube. The start-stop switch and the intermediate relay unit jointly complete the access and exit of the motor soft start soft turn-off and current-limiting operation control unit.

The utility model discloses an in an example, motor current detection unit, through detecting the electric current that flows through on the motor current detection resistance R0, obtain the voltage signal between S1+ and the S1-that this electric current produced, S1-connect in the 15V0 end of DC/DC02 power module, S1+ behind R11 resistance bias, connect in the homophase input end of A1B operational amplifier unit, the voltage signal between S1+ and the S1-passes through R12, the amplifying unit that R13 constitutes carries out the 100 times and enlargies the back, through the output of A1B operational amplifier unit, connect in the inverting input of the A1A operational amplifier unit in the soft start soft shutoff of motor and the current-limiting operation control unit.

The utility model discloses an in the example, soft shutoff of motor soft start and current-limiting operation control unit, put the unit homophase input end by R14 for A1A fortune and provide the upward biased resistance, R15 is the output resistor that A1A fortune was put the unit, the unit was put to A1A fortune cophase input, connect in the delay circuit who constitutes by EC01 and VR0 looks parallel connection, the unit was put to A1A fortune output unit, the direct access level keeps apart and the input of the signal conditioner TC01 among the drive unit, the 8 th foot of unit is put and is connect the 15V +, 4 feet of second group switching power supply, 15V0 connects S1-.

The utility model discloses an in the example, among the level isolation drive unit, after receiving the voltage signal that A1A fortune was put the output port and is given, through level isolation conversion conditioning, direct output is for the G utmost point and the S utmost point of IGBT switch tube. The power supply of the signal conditioner is provided by 24V1+ and 24V 1-of the first group of switching power supplies.

The utility model discloses an in an example, open stop switch with the auxiliary relay unit, by the 24V2+ and the 24V 2-power supply of third group switching power supply to accomplish the soft turn-off of starting of motor and the access or the withdraw from of the delay circuit that EC01 and VR01 constitute in the current-limiting operation control unit, D10 is reverse freewheel diode.

The utility model discloses an in the example, the integrated package is LF351 is put to fortune.

In one embodiment of the present invention, the IGBT is 2MBI 100N-120.

In one embodiment of the present invention, the signal conditioner is JY-DIN101-VTC 0.

By adopting the technical scheme, the method has the following technical effects:

the utility model relates to a device of soft start, soft shutoff and current-limiting operation of direct current motor.

When SA1 is not closed, the A1A operational amplifier unit has a non-inverting input connected to capacitors EC01 and VR01, and there is no charging loop, so EC01 is at 0V reference potential, and since there is no motor current, i.e. no voltage between S1+ and S1-, the output of A1B operational amplifier is also at 0V. At this time, the inverting input terminal of A1A is also 0V, so the output of the A1A operational amplifier unit is also 0V, the output terminal of the A1A operational amplifier unit, namely the Y point, is also 0V in the waveform of G01 point, and the IGBT switch tube is turned off when the motor is driven at 0V, and no current flows in the motor.

When SA1 is closed, the power voltage 15V + charges the ECO1 capacitor through R14, and the EC01 obtains a slowly rising voltage with a waveform of the voltage, i.e. the waveform of the voltage at the X point, at this time, the voltage is applied to the 3 rd pin, i.e. the non-inverting input, of the A1A operational amplifier unit, since no current flows in the motor before that, the output end of the A1B operational amplifier unit is 0V, and the output end is connected to the inverting input end of the A1A operational amplifier unit, so that the voltage at the inverting input end of the A1A operational amplifier unit follows the change of the non-inverting input, the A1A operational amplifier unit will output a suitable level signal, i.e. the voltage signal at the Y point, which is output to the point G01 after being isolated by the level isolation driving unit, and the voltage point will make the IGBT switch tube in an amplifying conducting state, which is equivalent to connecting a variable resistance value in series in the dc motor circuit, the resistor limits the loop current of the direct current motor to slowly rise. It can be seen that the current in the dc motor circuit is controlled entirely by the voltage on the EC01 capacitor. The net effect of this control is that the dc motor current follows the waveform on the EC01 capacitor voltage, rises proportionally, and eventually reaches a steady value. According to the adjusted VR01 value (which is connected with EC01 in parallel and the voltage of the VR01 value is identical), namely the maximum value of the load current of the motor in the same proportion. At this time, the regulated final voltage at VR01, which is also the final value of the voltage at EC01, should be greater than the voltage generated by the maximum dc motor current, so as to ensure that the IGBT operates in the saturated on state. When the direct current motor operates, the direct current motor current may increase for some reason, at this time, the voltage at the inverting input end of the A1A operational amplifier unit is higher than that at the non-inverting input end (i.e., point X), the voltage at the output end of the A1A operational amplifier unit, i.e., point Y, immediately outputs a lower voltage, the voltage value is output to point G01 after being isolated by the level isolation driving unit, the voltage value at this point makes the IGBT switch tube exit from saturation conduction, so that the IGBT switch tube is in an amplification state, which is equivalent to connecting a variable resistor in series in the direct current motor loop again, so that the direct current motor current is limited below the set value. When the SA1 is turned off again, the voltage on the EC01 capacitor decreases slowly, and at this time, the voltage signal generated by the motor current is higher than the voltage on the EC01, so that the output end of the A1A, i.e., the point Y, outputs a low voltage, which causes the IGBT switching tube to exit the saturated conduction state and enter the amplification state, and the IGBT switching tube acts as a variable resistor at this time, so that the current in the motor decreases slowly according to the corresponding value given by the voltage on the EC01, thereby obtaining the soft turn-off effect. Therefore, the purposes of soft starting, soft turn-off and current-limiting operation of the direct current motor are achieved by using the variable on-resistance of the IGBT switching tube.

Drawings

Fig. 1 is a schematic diagram of the system of the present invention;

fig. 2 is a waveform diagram of an X point of the control circuit of the present invention;

fig. 3 is a waveform diagram of the Y point and the G01 point output by the driving circuit of the present invention;

fig. 4 is a waveform diagram of the dc motor loop current (i.e., the voltage between S1+ and S1-);

1-a direct current motor; 2-reverse freewheeling diode; 3-IGBT switching tube; 4-motor current detection resistance; 5-a first set of switching power supplies; 6-a second group of switching power supplies III; 7-a third group of switching power supply groups is a direct current switching power supply; 8-a motor current detection unit; 9-a soft start soft shut-off and current-limiting operation control unit of the motor; 10-level isolation drive unit; 11-start-stop switch; 12-intermediate relay unit.

Detailed Description

In order to make the technical means, characteristics, objectives and functions of the present invention easy to understand, the present invention will be further explained with reference to the following drawings.

As shown in fig. 1, 2, 3, and 4, a device for soft start, soft shutdown, and current-limiting operation of a dc motor includes a dc motor 1, a reverse freewheeling diode 2, an IGBT switching tube 3, a motor current detection resistor 4, a first group of switching power supplies 5, a second group of switching power supplies 6, a third group of switching power supplies 7, a motor current detection unit 8, a motor soft start soft shutdown and current-limiting operation control unit 9, a level isolation driving unit 10, a start-stop switch 11, and an intermediate relay unit 12. One end of the direct current motor 1 is connected to a DC + pole of a power supply end, the other end of the direct current motor 1 is connected to a drain electrode of an IGBT (insulated gate bipolar transistor) switching tube, the reverse freewheeling diode 2 is connected in parallel with the direct current motor 1 in an opposite phase mode, a drain electrode of the IGBT switching tube 3 is connected to the other end of the direct current motor, a gate electrode of the IGBT switching tube is connected to a GO1 end of the level isolation driving unit 10, a source electrode of the IGBT switching tube is connected to an S1+ end of the motor current detection resistor 4, and an S1-. The first group of switching power supplies 5 provide power for modules in the level isolation driving unit 10, and the second group of switching power supplies 6 provide power and reference potential for the motor current detection unit 8 and the operational amplifier a1 of the motor soft start soft turn-off and current-limiting operation control unit 9. The third group of switching power supplies 7 has 24V 2-connected to one end of the start/stop switch 11, 24V2+ connected to one end of the intermediate relay unit 12, and the other end of the start/stop switch 11 is connected to the other end of the intermediate relay unit 12. The motor current detection unit 8 is composed of R11, R12, R13 and A1B, the motor soft start soft turn-off and current limiting operation control unit 9 is composed of R14, R15, R17, EC01, VR01 and A1A, an isolation module in the level isolation driving unit 10 is composed of TC01, an output positive terminal G01 of the TC01 is connected to a gate pole of the IGBT switch tube 3, an output negative terminal S pole is connected to a source pole of the IGBT switch tube 3, the start-stop switch 11 is composed of a self-locking button switch, and a normally open point of a relay K01 of the intermediate relay unit 12 is connected between the R14 and VR01 and EC01 in series. The reverse absorption diode in the intermediate relay unit 12 is connected in reverse parallel to the coil of K01.

The utility model discloses the during operation, when opening and stopping switch 11 not closed, the relay of intermediate relay unit 12 is not electrified, so, its normally open electric shock is not closed, EC01 and VR01 among the soft shutoff of motor start and the current-limiting operation control unit 9 are in 15V0 electric potential, the wave form of X point is 0 voltage promptly, simultaneously, the output is also 15V0 electric potential to the fortune of this unit, Y point output wave form is 0 electric potential promptly, the electric level is kept apart and drive unit 10's G01 also exports 0 electric potential this moment. The IGBT switch tube 3 is cut off, and no current passes through the direct current motor 1. When the start-stop switch 11 is closed, the relay of the intermediate relay unit 12 is electrified, the normally open contact thereof is closed, the voltages in the EC01 and VR01 in the motor soft start soft turn-off and current limit operation control unit 9 are slowly raised as the waveform of the point X in fig. 2, at this time, because no current exists in the motor, the current signal collected by the motor current detection unit 8 is amplified and then is 0 potential, at this time, the voltage of the reverse phase input end of the A1B operational amplification unit is changed to follow the voltage of the same phase input end, the output end of the motor soft start soft turn-off and current limit operation control unit 9 outputs a proper potential, at the same time, the level isolation and driving unit 10 converts the potential 1:1, the converted potential is output by the G01 to drive the IGBT switch organ 3, at this time, the IGBT switch tube 3 is in an amplified state and is equivalent to a variable resistor, so that, the current in the dc motor 1 is limited by this resistance and can only rise in proportion to the waveform at point X, when the waveform at point X continues to rise, the voltage between point Y (G01) and S1+ and S1-will rise according to the curves described in fig. 3 and 4, the course of which is shown in the rising phases of the curves in fig. 2, 3 and 4.

When the wave form of the point X is stable, the wave form of the point Y (G01) is also stable, at this moment, the IGBT switch tube 3 is in the saturated conducting state, the motor current reaches the maximum value, the current is completely determined by the DC motor 1 and the load characteristic thereof, when the loop current in the DC motor 1 suddenly increases for some reason, the motor current detecting unit 8 immediately detects, the motor soft start soft off and current limiting operation control unit 9 immediately outputs a lower level signal, thereby the IGBT switch tube 3 is out of the saturated conducting state, at this moment, the loop resistance corresponding to the DC motor 1 is increased, thereby the current is limited to a current value determined by the voltage on EC01, the change condition of the process is represented by the stable operation stage of the curves in fig. 2, fig. 3 and fig. 4.

When the start-stop switch 11 is turned off again, the voltage between the point X, the point Y (G01), the voltage between the point S1+ and the point S1-are just opposite to the voltage between the point X and the point Y (G01), and the process is just turned on, and the change conditions of the process are represented by the descending stages of the curves in fig. 2, 3 and 4, and are not described again.

Having described the basic principles and essential features of the invention, it will be understood by those skilled in the art that the present invention is not limited by the embodiments described above, which are merely illustrative of the principles of the invention, and that various changes and modifications may be made without departing from the spirit and scope of the invention, which fall within the scope of the invention as claimed, and which are defined by the appended claims and their equivalents.

Claims

1. A device for soft starting, soft turn-off and current-limiting operation of a direct current motor is characterized by comprising the direct current motor (1), a reverse freewheeling diode (2), an IGBT (insulated gate bipolar transistor) switching tube (3), a motor current detection resistor (4), a first group of switching power supplies (5), a second group of switching power supplies (6), a third group of switching power supplies (7), a motor current detection unit (8), a motor soft starting soft turn-off and current-limiting operation control unit (9), a level isolation driving unit (10), a start-stop switch (11) and an intermediate relay unit (12), wherein one end of the direct current motor (1) is connected to a DC + pole of a power supply end, the other end of the direct current motor is connected to a drain electrode of the IGBT switching tube (3), the reverse freewheeling diode (2) is connected in parallel to the direct current motor (1) in an opposite phase, and a drain electrode of the IGBT, the gate pole is connected with the output end of the level isolation driving unit (10), the source pole is connected with one end of the motor current detection resistor (4), the other end of the motor current detection resistor (4) is connected with the DC-end of the power supply end, the first group of switch power supply (5) provides power supply for the modules in the level isolation driving unit (10), the second group of switch power supply (6) provides power supply and reference potential for the motor current detection unit (8) and the operational amplifiers A1B and A1A of the motor soft start soft turn-off and current limiting operation control unit (9), the negative pole of the third group of switch power supply (7) is connected with one end of the start-stop switch (11), the positive pole is connected with one end of the intermediate relay unit (12), the input end of the motor current detection unit (8) is connected with the motor current detection resistor (4), and the output end is connected with the inverted input end of the motor soft start soft turn-off and current limiting operation control, the output end of the direct current motor soft start soft turn-off and current limiting operation control unit (9) is connected to the input end of a level isolation driving unit (10), the output end of the level isolation driving unit (10) is connected to the gate pole and the source pole of the IGBT switch tube (3), and the other end of the start-stop switch (11) is connected with the other end of the intermediate relay unit (12).

2. The device for soft starting, soft shutdown and current-limiting operation of the direct current motor according to claim 1 is characterized in that a motor current detection unit (8) is composed of a non-inverting proportional amplifier, the motor soft starting soft shutdown and current-limiting operation control unit (9) is composed of a voltage follower, and the normal open points of the on-off switch (11) and the relay of the intermediate relay (12) jointly control the input and the exit of the direct current motor soft starting soft shutdown and current-limiting operation control unit (9).

3. The device for soft start, soft turn-off and current-limiting operation of the direct current motor according to claim 1, wherein the IGBT switching tube (3) is an N-type IGBT tube.

4. The device for soft start, soft shut-off and current-limiting operation of the direct current motor as claimed in claim 1, wherein the voltage change of the non-inverting input terminal of the control unit (9) for soft start, soft shut-off and current-limiting operation of the motor is realized by resistance-capacitance charging and discharging.

5. The device for soft start, soft shut-off and current-limiting operation of a direct current motor according to claim 1, wherein the level isolation driving unit (10) is implemented by a signal conditioner.