Motor control circuit

Abstract

The utility model discloses a motor control circuit which comprises a frequency conversion module, a mode starting module and an adjusting module. The mode starting module is connected with the frequency conversion module and the adjusting module and used for controlling the frequency conversion module to output a first voltage signal in a first mode, and the adjusting module is connected with the frequency conversion module and used for adjusting the first voltage signal to form a first adjusting signal; the frequency conversion module is further used for controlling the running state of the motor according to the first adjusting signal. The motor control circuit provided by the utility model can realize frequency conversion regulation on the motor when the PLC fails.

Description

TECHNICAL FIELD

[0001] The utility model relates to motor control technical field especially relates to a motor control circuit. BACKGROUND

[0002] In the field of industrial automation, the combination of PLC (programmable logic controller) and servo motor is more and more widely used, and PLC can provide powerful logic control and data processing capabilities.

[0003] At present, the common method of controlling motor includes: contactor direct control and frequency converter indirect control, direct control is mostly used for power frequency starting, and frequency converter control is mostly used for stepless speed regulation control. However, the frequency converter control mode is often matched with PLC, so when the PLC fails, the power frequency starting controlled by the contactor becomes an emergency mode, and the motor cannot be controlled by the frequency converter for stepless speed regulation. SUMMARY

[0004] The utility model provides a motor control circuit to solve the problem that the motor cannot be controlled by the frequency converter for stepless speed regulation when the PLC fails in the prior art.

[0005] According to an aspect of the utility model, a motor control circuit is provided, which comprises a frequency conversion module, a mode starting module and an adjusting module.

[0006] The mode starting module is connected with the frequency conversion module and the adjusting module, and the mode starting module is used for controlling the frequency conversion module to output a first voltage signal in a first mode. The adjusting module is connected with the frequency conversion module, and the adjusting module is used for adjusting the first voltage signal to form a first adjusting signal. The frequency conversion module is further used for controlling the running state of the motor according to the first adjusting signal.

[0007] Optionally, the mode starting module comprises a first relay, a first end of a first normally open contact of the first relay is connected with a control end of the frequency conversion module, a second end of the first normally open contact of the first relay is connected with an adjusting end of the adjusting module, a first end of the adjusting module is connected with a first power supply end of the frequency conversion module, and the frequency conversion module is further used for controlling the running state of the motor according to the first adjusting signal received by the control end.

[0008] Optionally, the mode starting module further comprises a first contactor and a change-over switch, a first end of the change-over switch is connected with the power line, a second end of the change-over switch is connected with a first end of the second normally open contact of the first relay and a first end of the coil of the first relay, a second end of the second normally open contact of the first relay is connected with a first end of the coil of the first contactor and a fourth end of the change-over switch, a first end of the first normally open contact of the first contactor is connected with the second power supply end of the variable frequency module, a second end of the first normally open contact of the first contactor is connected with the speed selection end of the variable frequency module, a second end of the coil of the first relay and a second end of the coil of the first contactor are grounded.

[0009] Optionally, the adjusting module comprises a potentiometer, a first end of the potentiometer is connected with the first power supply end of the variable frequency module, a second end of the potentiometer is connected with the ground end of the variable frequency module, and an adjusting end of the potentiometer is connected with the second end of the first normally open contact of the first relay.

[0010] Optionally, the mode starting module further comprises a second contactor and a second relay, a third end of the change-over switch is connected with a first end of the first normally closed contact of the first relay, a second end of the first normally closed contact of the first relay is connected with a first end of the normally closed contact of the second relay, a second end of the normally closed contact of the second relay is connected with a first end of the coil of the second contactor, a second end of the coil of the second contactor is grounded, a first end of the normally open contact of the second contactor is connected with the power line, a second end of the normally open contact of the second contactor is connected with a first end of the coil of the second relay, and a second end of the coil of the second relay is connected with the motor.

[0011] Optionally, the change-over switch comprises a three-gear knob switch.

[0012] Optionally, the second relay is a thermal relay.

[0013] Optionally, a first end of the second normally open contact of the first contactor is connected with the variable frequency module, and a second end of the second normally open contact of the first contactor is connected with the motor.

[0014] Optionally, the variable frequency module further comprises a frequency converter, the frequency converter comprises an input terminal and an output terminal, the input terminal is connected with the power line, and the output terminal is connected with the motor.

[0015] Optionally, the motor control circuit further comprises a master control switch, the master control switch is connected with the variable frequency module and a motor main circuit, and the master control switch is used for turning on or turning off the power supply of the motor.

[0016] The utility model discloses a technical scheme of an embodiment, disclose a kind of motor control circuit, mode starting module is used to control frequency conversion module output first voltage signal in first mode, wherein, first mode is emergency mode (i.e.

[0017] It should be understood that the content described in this part is not intended to identify the key or important features of the embodiments of the utility model, and is not used to limit the scope of the utility model. Other features of the utility model will become easily understood through the following description. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical scheme in the embodiments of the utility model, the drawings needed to be used in the embodiment description will be simply introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and for those skilled in the art, other drawings can be obtained according to these drawings without creative labor.

[0019] Figure 1 It is a kind of motor control circuit structural schematic diagram provided by the utility model embodiment;

[0020] Figure 2 It is a kind of motor control circuit circuit diagram provided by the utility model embodiment;

[0021] Figure 3 It is another kind of motor control circuit circuit diagram provided by the utility model embodiment;

[0022] Figure 4 It is another kind of motor control circuit circuit diagram provided by the utility model embodiment. DETAILED DESCRIPTION

[0023] In order to make those skilled in the art better understand the utility model scheme, the technical scheme in the embodiments of the utility model will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model, obviously, the described embodiments are only part of the embodiments of the utility model, not all. Based on the embodiments in the utility model, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of the protection of the utility model.

[0024] It should be noted that the terms "first", "second", and the like in the description and claims of the utility model and the above drawings are used to distinguish like objects, and do not necessarily have to be described in a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances, so that the embodiments of the utility model described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion, for example, a process, method, system, product or device including a series of steps or units does not have to be limited to the clearly listed steps or units, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0025] The utility model embodiment provides a kind of motor control circuit, Figure 1 It is the structure diagram of a kind of motor control circuit provided by the utility model embodiment, as Figure 1 As shown, motor control circuit includes frequency conversion module 110, mode starting module 120 and adjustment module 130;Mode starting module 120 connects frequency conversion module 110 and the adjustment module, mode starting module 120 is used to control frequency conversion module 110 to output first voltage signal in the first mode, adjustment module 130 is connected with frequency conversion module 110, adjustment module 130 is used to adjust first voltage signal, forms first adjustment signal;Frequency conversion module 110 is also used to control the operating state of motor according to first adjustment signal.

[0026] In the embodiment, frequency conversion module 110 controls the module of motor frequency conversion work by changing output electric signal, for example, frequency conversion module 110 includes frequency converter.Mode starting module 120 is the module of controlling motor operating state and controlling motor operating state by controlling frequency conversion module.In emergency mode, mode starting module 120 starts the module of frequency conversion module 110, wherein, emergency mode refers to the control mode of motor when the PLC connected with frequency conversion module 110 and controlling frequency conversion module 110 fails.Adjustment module 130 is the module of adjusting electric signal output by frequency conversion module 110, for example, adjustment module 130 includes potentiometer.

[0027] In the embodiment, mode starting module 120 controls motor to enter the first mode (i.e. emergency mode), and frequency conversion module 110 starts and outputs first voltage signal, wherein the first voltage signal is provided by the power supply inside frequency conversion module 110, and the voltage value of the first voltage signal is a constant value.Adjustment module 130 can adjust the first voltage signal, and the first voltage signal forms first adjustment signal after being adjusted by adjustment module 130, and frequency conversion module 110 outputs the first adjustment signal, which serves as the power supply of motor, and since the first adjustment signal is a variable value, frequency conversion module 110 realizes frequency conversion control of motor.

[0028] The technical scheme of the embodiment discloses a motor control circuit, a mode starting module is used for controlling a variable frequency module to output a first voltage signal in a first mode, wherein the first mode is an emergency mode (i.e., when a PLC fails), an adjusting module is connected with the variable frequency module, the adjusting module adjusts the first voltage signal to form a first adjusting signal, instead of adjusting an output signal of the variable frequency module by the PLC, and the variable frequency module controls a running state of a motor according to the first adjusting signal, so that the variable frequency module can still perform frequency conversion adjustment on the motor when the PLC fails, and the problem that the motor cannot be steplessly speed-regulated and controlled by a frequency converter when the PLC fails in the prior art is solved.

[0029] Figure 2 is a circuit diagram of the motor control circuit, as shown in Figure 2 The mode starting module 120 comprises a first relay K1, a first end of a first normally-open contact of the first relay K1 is connected with a control end AI1 of the variable frequency module 110, a second end of the first normally-open contact of the first relay K1 is connected with an adjusting end of the adjusting module 130, a first end of the adjusting module 130 is connected with a first power supply end V1 of the variable frequency module 110, and the variable frequency module 110 is further used for controlling a running state of a motor according to the first adjusting signal received by the control end AI1.

[0030] In the embodiment, the control end AI1 of the variable frequency module 110 is used for connecting the PLC, a control signal output by the PLC is transmitted to the variable frequency module through the control end AI1, the variable frequency module adjusts a voltage signal transmitted to the motor according to the received control signal, and frequency conversion control is realized on the motor. Specifically, the control end AI1 of the variable frequency module 110 is connected with a first end of a first normally-closed contact of the first relay K1, a second end of the first normally-closed contact of the first relay K1 is connected with the PLC (not shown in the figure), and on the basis of the above embodiment, when the PLC fails, i.e., in the emergency mode, the mode starting module 120 controls to start the variable frequency module 110, at this time, the first normally-closed contact of the first relay K1 is disconnected, the first normally-open contact of the first relay K1 is closed, the control end AI1 of the variable frequency module 110 is disconnected with the PLC, and is connected with the adjusting module 130 at the same time, the adjusting module 130 is manually adjusted, instead of adjusting the output signal of the variable frequency module by the PLC, the variable frequency module controls the running state of the motor according to the first adjusting signal, and the variable frequency module can still perform frequency conversion adjustment on the motor when the PLC fails.

[0031] Figure 3 is a circuit diagram of another motor control circuit provided by the utility model embodiment, referring to Figure 2 and Figure 3, the mode starting module 120 further comprises a first contactor J1 and a change-over switch SW1, a first end of the change-over switch SW1 is connected with a power line, a second end of the change-over switch SW1 is connected with a first end of a second normally open contact of a first relay K1 and a first end of a coil of the first relay K1, a second end of the second normally open contact of the first relay K1 is connected with a first end of a coil of the first contactor J1 and a fourth end of the change-over switch SW1, a first end of a first normally open contact of the first contactor J1 is connected with a second power supply end V2 of the frequency conversion module 110, a second end of the first normally open contact of the first contactor J1 is connected with a speed selection end D1 of the frequency conversion module 110, a second end of the coil of the first relay K1 and a second end of the coil of the first contactor J1 are grounded.

[0032] In the embodiment, the power line is three-phase alternating current, including a zero line N and three-phase live lines U, V and W, wherein a U phase of the three-phase alternating current is connected with the first end of the change-over switch SW1, and the second end of the coil of the first relay K1 and the second end of the coil of the first contactor J1 are connected with the zero line N.

[0033] Continuing to refer to Figure 2 The adjusting module 130 comprises a potentiometer P, a first end of the potentiometer P is connected with the first power supply end V1 of the frequency conversion module 110, a second end of the potentiometer P is connected with a ground end GND of the frequency conversion module 110, and an adjusting end of the potentiometer P is connected with the second end of the first normally open contact of the first relay K1.

[0034] In the embodiment, the voltage output by the first power supply end V1 is 10V, after the frequency conversion module 110 is started, the first normally open contact of the first relay K1 is closed, so that the adjusting end of the potentiometer P is connected with the control end AI1 of the frequency conversion module 110, and the voltage output by the frequency conversion module 110 is controlled by manually adjusting the potentiometer P.

[0035] Figure 4 is another circuit diagram of a motor control circuit provided by the embodiment of the utility model, like Figure 3 andFigure 4 As shown, the mode starting module 120 further comprises a second contactor J2 and a second relay K2, the first end of the change-over switch SW1 is connected to a power line, the third end of the change-over switch SW1 is connected to the first end of the first normally closed contact of the first relay K1, the second end of the first normally closed contact of the first relay K1 is connected to the first end of the normally closed contact of the second relay K2, the second end of the normally closed contact of the second relay K2 is connected to the first end of the coil of the second contactor J2, the second end of the coil of the second contactor J2 is grounded, the first end of the normally open contact of the second contactor J2 is connected to the power line, the second end of the normally open contact of the second contactor J2 is connected to the first end of the coil of the second relay K2, the second end of the coil of the second relay K2 is connected to the motor M.

[0036] In the embodiment, after the first end and the third end of the change-over switch SW1 are connected, the motor is in the power frequency starting mode, i.e., the motor is directly controlled by the contactor (without passing through the frequency conversion module), so that the motor works in the power frequency state and has the characteristic of fast starting. Specifically, the second relay K2 is a thermal relay and serves as an overload protection element of the motor. After the first end and the third end of the change-over switch SW1 are connected, the coil of the second contactor J2 is powered, the normally open contact of the second contactor J2 is closed, the motor M is connected to three-phase alternating current, and the motor M is started.

[0037] With reference to Figure 2 and Figure 3 , the change-over switch SW1 is a three-position knob switch. After the first end and the fourth end of the change-over switch SW1 are connected, the motor is in the frequency conversion mode. In the frequency conversion mode, the frequency conversion module 110 adjusts the output voltage according to the control signal received by the control end AI1 from the PLC to control the running state of the motor. Specifically, after the first end and the fourth end of the change-over switch SW1 are connected, the coil of the first contactor J1 is powered, the first normally open contact of the first contactor J1 is closed, the second power end V2 of the frequency conversion module 110 is connected to the speed selection end D1 of the frequency conversion module 110, the frequency conversion module 110 is turned on, and the frequency conversion module 110 adjusts the output voltage according to the control signal received by the control end AI1 from the PLC, for example, the frequency conversion module 110 controls the motor to be infinitely speed-adjusted in the range of 0-50 HZ.

[0038] With reference to Figure 4The variable frequency module 110 further comprises a frequency converter VFD, the frequency converter VFD comprises input terminals and output terminals, the input terminals are connected with power lines, and the output terminals are connected with the motor M. The frequency converter VFD is a power control device for controlling the motor by changing the frequency of the power supply of the motor through the application of variable frequency technology and microelectronic technology. The input terminals of the frequency converter VFD comprise a first input terminal, a second input terminal and a third input terminal, which are connected with three-phase live wires U, V and W of three-phase alternating current respectively, the output terminals of the frequency converter VFD comprise a first output terminal, a second output terminal and a third output terminal, the output terminals of the frequency converter VFD are connected with the first end of the second normally open contact of the first contactor J1, the second end of the second normally open contact of the first contactor J1 is connected with the three-phase input terminals of the motor M, and the second normally open contact of the first contactor J1 is closed when the coil of the first contactor J1 is electrified. The second contactor J2 is interlocked with the first contactor J1, so that when one of the contactors works, the other contactor is in a non-working state, thereby avoiding the short circuit or damage of the motor caused by the simultaneous connection of the two contactors.

[0039] With reference to the above description Figure 4 The motor control circuit further comprises a master control switch MCB, the master control switch MCB is connected with the variable frequency module 110 and the motor main circuit, and the master control switch MCB is used for turning on or cutting off the power supply of the motor M. The master control switch MCB is a low-voltage circuit breaker, which is an important control and protection electrical appliance and realizes overload protection, short circuit protection and under-voltage protection for a circuit and an electrical appliance.

[0040] In the embodiment, after the master control switch MCB is closed, three-phase alternating current is connected to the motor main circuit. On the basis of the above embodiment, the running mode of the motor is controlled by rotating the conversion switch SW1. After the first end and the third end of the conversion switch SW1 are connected, the motor works in a power frequency state. After the first end and the fourth end of the conversion switch SW1 are connected, the variable frequency module 110 is started, the variable frequency module 110 adjusts the output voltage according to the control signal output by the PLC, and the motor is controlled to realize stepless speed regulation. When the PLC fails, that is, in an emergency mode, after the first end and the second end of the conversion switch SW1 are connected, the output signal of the variable frequency module is adjusted manually instead of by the PLC, the variable frequency module controls the running state of the motor according to the first adjustment signal, and the variable frequency module can still control the motor to realize stepless speed regulation when the PLC fails.

[0041] It should be understood that the various forms of flow shown above can be reordered, added to, or deleted from. For example, the steps described in the present application can be executed in parallel, in sequence, or in different orders, as long as the desired results of the technical solutions of the present application can be achieved, and the present application does not limit this.

[0042] The specific embodiments described above do not constitute a limitation on the protection scope of the present application. Those skilled in the art should understand that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A motor control circuit, characterized in that, Includes a frequency converter module, a mode start-up module, and a regulation module; The mode start module is connected to the frequency converter module and the adjustment module. The mode start module is used to control the frequency converter module to output a first voltage signal in a first mode. The adjustment module is connected to the frequency converter module and is used to adjust the first voltage signal to form a first adjustment signal. The frequency converter module is also used to control the operating state of the motor according to the first adjustment signal. The first mode is an emergency mode, which is used to activate when the PLC fails. The adjustment module includes a potentiometer for manually adjusting the first voltage signal; The mode start module includes a first relay, a first contactor, and a changeover switch. The changeover switch is used to select between power frequency mode, frequency conversion mode, or emergency mode. In the emergency mode, the first relay switches the control signal path to the adjustment module, and the first contactor connects the power and speed selection terminals of the frequency conversion module.

2. The motor control circuit according to claim 1, characterized in that, The first end of the first normally open contact of the first relay is connected to the control terminal of the frequency converter module, and the second end of the first normally open contact of the first relay is connected to the adjustment terminal of the adjustment module. The first terminal of the adjustment module is connected to the first power supply terminal of the frequency converter module. The frequency converter module is also used to control the operating state of the motor according to the first adjustment signal received by the control terminal.

3. The motor control circuit according to claim 2, characterized in that, The first end of the changeover switch is connected to the power supply line. The second end of the changeover switch is connected to the first end of the second normally open contact of the first relay and the first end of the coil of the first relay. The second end of the second normally open contact of the first relay is connected to the first end of the coil of the first contactor and the fourth end of the changeover switch. The first end of the first normally open contact of the first contactor is connected to the second power supply terminal of the frequency converter module. The second end of the first normally open contact of the first contactor is connected to the speed selection terminal of the frequency converter module. The second end of the coil of the first relay and the second end of the coil of the first contactor are grounded.

4. The motor control circuit according to claim 2, characterized in that, The first end of the potentiometer is connected to the first power supply terminal of the frequency converter module, the second end of the potentiometer is connected to the ground terminal of the frequency converter module, and the adjustment terminal of the potentiometer is connected to the second end of the first normally open contact of the first relay.

5. The motor control circuit according to claim 3, characterized in that, The mode start module also includes a second contactor and a second relay. The third terminal of the changeover switch is connected to the first terminal of the first normally closed contact of the first relay. The second terminal of the first normally closed contact of the first relay is connected to the first terminal of the normally closed contact of the second relay. The second terminal of the normally closed contact of the second relay is connected to the first terminal of the coil of the second contactor. The second terminal of the coil of the second contactor is grounded. The first terminal of the normally open contact of the second contactor is connected to the power line. The second terminal of the normally open contact of the second contactor is connected to the first terminal of the coil of the second relay. The second terminal of the coil of the second relay is connected to the motor.

6. The motor control circuit according to claim 3, characterized in that, The selector switch includes a three-position rotary switch.

7. The motor control circuit according to claim 5, characterized in that, The second relay is a thermal relay.

8. The motor control circuit according to claim 3, characterized in that, The first end of the second normally open contact of the first contactor is connected to the frequency converter module, and the second end of the second normally open contact of the first contactor is connected to the motor.

9. The motor control circuit according to claim 1, characterized in that, The frequency conversion module also includes a frequency converter, which has input terminals and output terminals. The input terminals are connected to a power supply line, and the output terminals are connected to the motor.

10. The motor control circuit according to claim 1, characterized in that, It also includes a main control switch, which connects the frequency converter module and the motor main circuit. The main control switch is used to turn on or off the power supply to the motor.

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