CN220935039U - Frequency converter control system and frequency converter applied by same - Google Patents

Abstract

The utility model provides a frequency converter control system and a frequency converter applied by the same, wherein the frequency converter control system comprises a frequency conversion loop and a forced cooling fan loop; the input end of the variable frequency loop is electrically connected with the mains supply, and the output end of the variable frequency loop is electrically connected with the variable frequency motor; the input end of the forced cooling fan loop is electrically connected with the commercial power, and the output end of the forced cooling fan loop is electrically connected with the forced cooling fan motor; the frequency conversion circuit comprises a frequency conversion circuit, a main circuit breaker, a parallel main circuit and a bypass circuit, wherein the main circuit breaker is electrically connected between an input end and an output end of the frequency conversion circuit, and the parallel main circuit and the bypass circuit are electrically connected with the main circuit breaker. According to the utility model, the main loop and the bypass loop are arranged, so that when the frequency converter fails, the frequency converter can be switched to the bypass loop to supply power to the frequency conversion motor; based on the self-holding of the alternating current contactor coil, the functions of manual and automatic bidirectional switching and no shutdown of the frequency converter motor can be realized; under the condition that the forced cooling fan is stopped or the temperature of the coil of the variable frequency motor is too high, the system can interlock the stop of the variable frequency motor so as to protect the variable frequency water pump or the fan.

Description

Frequency converter control system and frequency converter applied by same

Technical Field

The utility model relates to the technical field of frequency converter control, in particular to a frequency converter control system and a frequency converter applied by the same.

Background

Currently, as equipment common in industrial production, the working efficiency and energy consumption of water pumps and fans are always the focus of attention. Traditional water pump and fan adopt fixed rotational speed drive generally, can't adjust according to actual demand, lead to the extravagant and the operating efficiency low of energy. The frequency converter well solves the problem. The frequency converter realizes the accurate control of the water pump and the fan by adjusting the rotating speed of the motor. The motor speed can be automatically adjusted according to actual demands, so that the motor is always kept in a working state, and the running efficiency of equipment is improved. Meanwhile, the frequency converter can adjust the load of the motor in real time according to the change of the working load, so that the energy waste of the motor when the motor runs under low load is avoided, and the energy utilization rate is further improved.

More and more industrial water pumps and fans select variable-frequency water pumps and fans for energy saving and adjustment, and the variable-frequency water pumps and fans are the water pumps and fans for setting the frequency converter to work. However, when the frequency converter fails, the system in which the frequency converter is positioned is easy to operate, so that the water pump or the fan cannot work.

Disclosure of utility model

In view of the above-mentioned drawbacks of the prior art, the present utility model provides a control system for a frequency converter and a frequency converter applied by the same, which are used for helping to solve the problems in the prior art that when the frequency converter fails, the system in which the frequency converter is located is easy to fail to operate, and thus the water pump or the fan cannot work.

To achieve the above and other related objects, a first aspect of the present utility model provides a control system for a frequency converter, including a frequency conversion circuit and a forced cooling fan circuit; the input end of the variable frequency loop is electrically connected with the mains supply, and the output end of the variable frequency loop is electrically connected with the variable frequency motor; the input end of the forced cooling fan loop is electrically connected with the commercial power, and the output end of the forced cooling fan loop is electrically connected with the forced cooling fan motor; a main circuit breaker, a main circuit and a bypass circuit which are electrically connected in parallel and are electrically connected with the main circuit breaker are electrically connected between the input end and the output end of the variable frequency circuit; and a branch breaker, a first alternating current contactor and a first thermal relay are connected in series between the input end and the output end of the forced cooling fan loop.

In some embodiments of the first aspect of the utility model, the main circuit comprises a second ac contactor, a frequency converter, and a fourth ac contactor in series; and the bypass loop includes a third ac contactor and a second thermal relay in series.

In some embodiments of the first aspect of the present utility model, the main loop is provided with a corresponding main control circuit; the main control circuit comprises a live wire and a zero wire; the live wire is connected with at least one fuse; the live wire is provided with a power circuit, a manual and automatic switching circuit, a frequency converter fault output circuit, a frequency converter state output circuit, a fan starting and frequency converter motor linkage circuit, a frequency conversion main loop contactor linkage circuit, a frequency converter fault indication circuit, a frequency converter state indication circuit, a frequency converter motor overheat signal circuit and a fan overload circuit which are connected in parallel through the fuse and the zero line; the frequency converter fault output circuit and the frequency converter state output circuit are respectively and electrically connected with the frequency converter.

In some embodiments of the first aspect of the present utility model, the power circuit includes at least one power indicator light; the manual automatic switching circuit comprises a first change-over switch; the first transfer switch is connected with and controls the starting unit and the stopping unit; the starting unit consists of a manual starting circuit and an automatic starting circuit which are connected in parallel; the stopping unit consists of a manual stopping circuit and an automatic stopping circuit which are connected in parallel; the frequency converter fault output circuit comprises a coil of a third intermediate relay electrically connected with a fault output end of the frequency converter; the frequency converter state output circuit comprises a coil of a fourth intermediate relay electrically connected with the running state output end of the frequency converter; the fan starting and variable frequency motor linkage circuit comprises a first normally-open contact of a first intermediate relay, a first normally-closed contact of a second intermediate relay, a first normally-closed contact of a fifth intermediate relay, a first normally-closed contact of a sixth intermediate relay, coils of a first alternating-current contactor, a second normally-open contact of the first alternating-current contactor, which is connected in parallel with two ends of the first normally-open contact of the first intermediate relay, and operation indicator lamps, which are connected in parallel with two ends of the coils of the first alternating-current contactor; the frequency conversion main loop contactor interlocking circuit comprises a sixth normally-open contact of a first intermediate relay, a second normally-closed contact of a seventh intermediate relay, a second normally-closed contact of a third alternating-current contactor and coils of a second alternating-current contactor which are connected in series, and a coil of a fourth alternating-current contactor and a third running indicator lamp which are respectively connected in parallel at two ends of the coil of the second alternating-current contactor; the coil of the fourth alternating current contactor is connected with the third running indicator lamp in parallel; the frequency converter fault indication circuit comprises a first normally open contact and a fault indication lamp of a third intermediate relay which are connected in series; the frequency converter state indicating circuit comprises a first normally open contact of a fourth intermediate relay and the running indicator lamp which are connected in series; the variable frequency motor overheat signal circuit comprises a variable frequency motor internal temperature switch and a coil of a fifth intermediate relay which are connected in series, and fault indicator lamps connected in parallel at two ends of the coil of the fifth intermediate relay; the fan overload circuit comprises a first normally open contact of a first thermal relay and a coil of a sixth intermediate relay which are connected in series, and fault indicator lamps connected in parallel at two ends of the coil of the sixth intermediate relay.

In some embodiments of the first aspect of the present utility model, the manual starting circuit includes a first push button switch and a coil of a first intermediate relay in series; the automatic starting circuit comprises a PLC starting switch; the manual stopping circuit comprises a second button switch; the automatic stopping circuit comprises a PLC stopping switch and a coil of a second intermediate relay which are connected in series.

In some embodiments of the first aspect of the present utility model, the bypass loop is provided with a corresponding auxiliary control circuit; the auxiliary control circuit comprises a frequency converter fault delay switching bypass circuit, a bypass manual and automatic control circuit and a bypass overload signal circuit which are connected in parallel.

In some embodiments of the first aspect of the present utility model, the frequency converter fault-delay switching bypass circuit includes a third normally open contact of a third intermediate relay and a coil of a first delay relay in series, and a first normally open contact of the first delay relay and a coil of a seventh intermediate relay in series connected in parallel across the third normally open contact of the third intermediate relay and the coil of the first delay relay in series; the coil of the second delay relay is connected in parallel with the two ends of the coil of the seventh intermediate relay; the two ends of the first normally open contact of the first delay relay are connected with the first normally open contact of the seventh intermediate relay in parallel; the coil of the second delay relay is connected with the first normally open contact of the seventh intermediate relay in parallel; the bypass manual automatic control circuit comprises a second change-over switch, a bypass manual control circuit and a bypass automatic control circuit which are electrically connected with the second change-over switch in parallel; the bypass overload signal circuit comprises a first normally open contact of a second thermal relay and coils of an eighth intermediate relay which are connected in series, and second fault indicator lamps which are connected in parallel at two ends of the coils of the eighth intermediate relay.

In some embodiments of the first aspect of the present utility model, the bypass manual control circuit includes a second switch selector, a second push button switch, a first normally closed contact of an eighth intermediate relay, a second normally closed contact of a fifth intermediate relay, a first normally closed contact of a first ac contactor, and a coil of a third ac contactor connected in series, and a first normally open contact of a second ac contactor connected in parallel to both ends of the second push button switch, and a second running indicator lamp connected in parallel to both ends of the coil of the third ac contactor; and the bypass automatic control circuit comprises a fifth normally open contact of the first intermediate relay and a first normally open contact of the second delay relay which are connected in series.

In some embodiments of the first aspect of the utility model, the frequency converter includes a power input port R, S, T and a power output port U, V, W; the power input port R, S, T of the frequency converter is electrically connected with the mains supply through a second alternating-current contactor and a main breaker which are connected in series; the power output port U, V, W of the frequency converter is electrically connected to the variable frequency motor through the fourth ac contactor.

In some embodiments of the first aspect of the present utility model, the frequency converter further includes a start-up contact port, an analog input port, an analog output port, and a ground port; the starting contact port is connected with a first normally-closed contact of the first alternating-current contactor in parallel; the analog input port is connected with a 4-20mA input circuit in parallel; the analog output port is connected with a 4-20mA output circuit in parallel; the ground port is grounded.

To achieve the above and other related objects, a second aspect of the present utility model provides a frequency converter including a frequency converter control system.

As described above, the frequency converter control system and the frequency converter applied by the frequency converter control system provided by the utility model have the following beneficial effects: by arranging the main loop and the bypass loop, when the frequency converter fails, the frequency converter can be switched to the bypass loop to supply power for the frequency conversion motor; based on the self-holding of the alternating current contactor coil, the functions of manual and automatic bidirectional switching and no shutdown of the frequency converter motor can be realized; under the condition that the forced cooling fan is stopped or the temperature of the coil of the variable frequency motor is too high, the system can interlock the stop of the variable frequency motor so as to protect the variable frequency water pump or the fan.

Drawings

Fig. 1 is a schematic diagram of a control system of a frequency converter according to an embodiment of the utility model.

Fig. 2 is a schematic diagram of a main control circuit of a main loop according to an embodiment of the utility model.

Fig. 3 is a schematic diagram of a secondary control circuit of a bypass circuit according to an embodiment of the utility model.

Description of element reference numerals

100. Frequency conversion loop

110. Bypass loop

120. Main loop

200. Forced cooling fan loop

Detailed Description

Further advantages and effects of the present utility model will become apparent to those skilled in the art from the disclosure of the present utility model, which is described by the following specific examples.

It should be understood that the structures, proportions, sizes, etc. shown in the drawings are for illustration purposes only and should not be construed as limiting the utility model to the extent that it can be practiced, since modifications, changes in the proportions, or otherwise, used in the practice of the utility model, are not intended to be critical to the essential characteristics of the utility model, but are intended to fall within the spirit and scope of the utility model. The following detailed description is not to be taken in a limiting sense, and the scope of embodiments of the present utility model is defined only by the claims of the issued patent. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the utility model. Spatially relative terms, such as "upper," "lower," "left," "right," "lower," "upper," and the like, may be used herein to facilitate a description of one element or feature as illustrated in the figures as being related to another element or feature.

In the present utility model, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," "held," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present utility model can be understood by those of ordinary skill in the art according to the specific circumstances.

Furthermore, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context indicates otherwise. It will be further understood that the terms "comprises," "comprising," "includes," and/or "including" specify the presence of stated features, operations, elements, components, items, categories, and/or groups, but do not preclude the presence, presence or addition of one or more other features, operations, elements, components, items, categories, and/or groups. The terms "or" and/or "as used herein are to be construed as inclusive, or meaning any one or any combination. Thus, "A, B or C" or "A, B and/or C" means "any of the following: a, A is as follows; b, a step of preparing a composite material; c, performing operation; a and B; a and C; b and C; A. b and C). An exception to this definition will occur only when a combination of elements, functions or operations are in some way inherently mutually exclusive.

In order to make the objects, technical solutions and advantages of the present utility model more apparent, further detailed description of the technical solutions in the embodiments of the present utility model will be given by the following examples with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the utility model.

As shown in fig. 1, a schematic structural diagram of a frequency converter control system according to an embodiment of the present utility model is shown, including a frequency conversion circuit 100 and a forced cooling fan circuit 200; the input end of the frequency conversion loop 100 is electrically connected with the mains supply, and the output end thereof is electrically connected with the variable frequency motor M; the input end of the forced cooling fan circuit 200 is electrically connected with the commercial power, and the output end thereof is electrically connected with the forced cooling fan motor FM; wherein, a main breaker QF1, a parallel main loop 120 and a bypass loop 110 electrically connected with the main breaker QF1 are electrically connected between the input end and the output end of the variable frequency loop 100; a branch breaker QF2, a first ac contactor 1KM and a first thermal relay 1KH are connected in series between the input end and the output end of the strong cooling fan circuit 200. The power input terminals connected with the mains supply are an L1 terminal, an L2 terminal and an L3 terminal, the accessed alternating current power supply can be divided into two specifications of 220V single phase and 380V three phase according to different application voltages, and the two specifications can be selected according to actual requirements, and the embodiment of the utility model is not limited.

In some examples, the main circuit 120 includes a second ac contactor 2KM, a frequency converter VFD, and a fourth ac contactor 4KM in series; and the bypass circuit 110 includes a third ac contactor 3KM and a second thermal relay 2KH connected in series.

It should be noted that the variable frequency water pump or the fan comprises a variable frequency motor and a forced cooling fan motor. The variable frequency motor is mainly responsible for driving the water pump and the fan; the forced cooling fan motor is used for driving the forced cooling fan and carrying out heat dissipation and cooling on the coil of the variable frequency motor.

Further, under the condition that the inverter normally works, the main breaker QF1 and the branch breaker QF2 in the inverter circuit 100 are kept in a closed state all the time, and the second ac contactor 2KM and the fourth ac contactor 4KM of the main circuit and the first ac contactor 1KM of the forced cooling fan circuit 200 are closed through the system control. At this time, the current is transmitted to the variable frequency motor M through the second ac contactor 2KM, the variable frequency converter VFD and the fourth ac contactor 4KM connected in series in the main circuit to supply power to the variable frequency motor M, and the current is transmitted to the strong cooling fan motor FM through the branch breaker QF2, the first ac contactor 1KM and the first thermal relay 1KH connected in series in the strong cooling fan circuit to supply power to the strong cooling fan motor FM.

In this embodiment, the system can directly isolate the frequency converter, switch the main loop 120 to the bypass loop 110, and directly supply power to the variable frequency motor M through the bypass loop 110 to ensure that the variable frequency water pump or the fan works normally.

As shown in fig. 2, a schematic diagram of the main control circuit of the main loop 120 in an embodiment of the present utility model is shown. The main circuit 120 is provided with a corresponding main control circuit; the main control circuit comprises a live wire L and a zero wire N; the live wire L is connected with at least one fuse FU1; the live wire L is provided with a power supply circuit, a manual and automatic switching circuit, a frequency converter fault output circuit, a frequency converter state output circuit, a fan starting and frequency conversion motor linkage circuit, a frequency conversion main loop contactor linkage circuit, a frequency converter fault indication circuit, a frequency converter state indication circuit, a frequency conversion motor overheat signal circuit and a fan overload circuit which are connected in parallel through the fuse FU1 and the zero line N; the frequency converter fault output circuit and the frequency converter state output circuit are respectively and electrically connected with the frequency converter VFD. The fuse FU1 is a protection electric appliance, and the model selection of the fuse FU1 can be selected according to actual requirements.

In one embodiment, the power circuit includes at least one power indicator HG; whether mains supply is connected or whether power supply is normal can be intuitively observed through the power indicator lamp.

The manual automatic switching circuit comprises a first change-over switch SA1; the first transfer switch SA1 is connected with and controls a starting unit and a stopping unit; the starting unit consists of a manual starting circuit and an automatic starting circuit which are connected in parallel; the stopping unit is composed of a manual stopping circuit and an automatic stopping circuit which are connected in parallel. In some examples, the manual starting circuit includes a first push button switch SF1 and a coil of a first intermediate relay 1KA in series; the automatic starting circuit comprises a PLC starting switch; the manual stopping circuit comprises a second button switch SF2; the automatic stopping circuit comprises a PLC stopping switch and a coil of a second intermediate relay 2KA which are connected in series. The PLC starting switch and the PLC stopping switch are controlled to be turned on or turned off through a programmable controller PLC.

Specifically, the frequency converter can realize manual and automatic bidirectional switching through the manual and automatic switching circuit and the function that the frequency converter motor is not shut down, and is mainly realized through the self-holding function of the alternating current contactor coil. The self-holding of an ac contactor is a method of using elements in a circuit to maintain the contactor in a closed state after the control power is turned off, and the principle is to connect an element capable of storing electric energy in parallel or in series in the coil of the ac contactor so that the element can continue to supply electric energy to the coil when the contactor is powered off, thereby maintaining the contactor in the closed state. In the system, the self-holding of the first alternating current contactor 1KM can be used for manually and automatically switching in a bidirectional mode, and the frequency converter motor is not stopped, namely, the power supply state before switching is maintained, so that the flexibility of manual and automatic bidirectional switching is greatly improved. The frequency converter fault output circuit comprises a coil of a third intermediate relay 3KA electrically connected with a fault output end of the frequency converter VFD. The fault signal of the frequency converter can be uploaded to the upper computer through the second normally open contact 3KA2 of the third intermediate relay 3KA and detected.

The frequency converter state output circuit comprises a coil of a fourth intermediate relay 4KA electrically connected with the operation state output end of the frequency converter VFD. The operating state signal of the frequency converter can be uploaded to the upper computer through the second normally open contact 4KA2 of the fourth intermediate relay 4KA and detected.

The fan starting and variable frequency motor linkage circuit comprises a first normally-open contact 1KA1 of a first intermediate relay 1KA, a first normally-closed contact 2KA1 of a second intermediate relay 2KA, a first normally-closed contact 5KA1 of a fifth intermediate relay 5KA, a first normally-closed contact 6KA1 of a sixth intermediate relay 6KA, a coil of a first alternating-current contactor 1KM, a second normally-open contact 1KM2 of the first alternating-current contactor 1KM connected in parallel at two ends of the first normally-open contact 1KA1 of the first intermediate relay 1KA, and an operation indicator lamp HR connected in parallel at two ends of the coil of the first alternating-current contactor 1 KM. The first normally open contact 1KA1 of the first intermediate relay 1KA is in a linkage state of fan starting and variable frequency motor after being connected, and at the moment, the forced cooling fan motor and the variable frequency motor are in a power supply state, and the forced cooling fan motor drives the forced cooling fan to perform heat dissipation and cooling for a coil of the variable frequency motor.

The frequency conversion main loop contactor interlocking circuit comprises a sixth normally-open contact 1KA6 of a first intermediate relay 1KA, a second normally-closed contact 7KA2 of a seventh intermediate relay 7KA, a second normally-closed contact 3KM2 of a third alternating-current contactor 3KM, coils of the second alternating-current contactor 2KM, coils of a fourth alternating-current contactor 4KM and a third running indicator lamp HR3 which are respectively connected in parallel at two ends of the coils of the second alternating-current contactor 2 KM; the coil of the fourth ac contactor 4KM is connected in parallel with the third operation indicator lamp HR 3. The sixth normally open contact 1KA6 of the first intermediate relay 1KA is communicated, and then the second alternating current contactor 2KM and the fourth alternating current contactor 4KM in the main loop are interlocked.

The frequency converter fault indication circuit comprises a first normally open contact 3KA1 of a third intermediate relay 3KA and a fault indicator lamp HY which are connected in series. The fault signal reminding of the frequency converter can be sent out through the fault indicator HY, for example, if the fault indicator HY lights up, the frequency converter is indicated to be faulty.

The frequency converter state indicating circuit comprises a first normally open contact 4KA1 of a fourth intermediate relay 4KA and the operation indicating lamp HR which are connected in series. The operation state of the frequency converter can be displayed through the operation indicator lamp HR, for example, the operation indicator lamp HR is always lighted, and the normal operation of the frequency converter is indicated.

The variable frequency motor overheat signal circuit comprises a variable frequency motor internal temperature switch and a coil of a fifth intermediate relay 5KA which are connected in series, and fault indicator lamps HY which are connected in parallel with two ends of the coil of the fifth intermediate relay 5 KA. The internal temperature switch of the variable frequency motor receives the internal temperature switch signal of the variable frequency motor to be communicated, and the fault indicator lamp HY lights to remind the variable frequency motor that the coil temperature is too high.

Under the condition that the main loop 120 or the bypass loop 110 supplies power to the variable frequency motor, when the forced cooling fan stops working or the coil temperature of the variable frequency motor is too high, the coil of the fifth intermediate relay 5KA is interlocked, so that the first alternating current contactor 1KM, the second alternating current contactor 2KM and the third alternating current contactor 3KM are interlocked to be disconnected and power-off, the variable frequency motor is interlocked to stop and the forced cooling fan motor is interlocked to stop, so that the variable frequency water pump or the fan and the forced cooling fan are closed, and the variable frequency motor is prevented from being burnt out due to no air cooling fan heat.

The fan overload circuit comprises a first normally open contact 1KH1 of a first thermal relay 1KH and coils of a sixth intermediate relay 6KA which are connected in series, and fault indicator lamps HY which are connected in parallel with two ends of the coils of the sixth intermediate relay 6 KA. The fan overload signal can be uploaded to the host computer through the second normally open contact 6KA2 of the sixth intermediate relay 6KA and detected.

In one embodiment, the bypass loop 110 is provided with a corresponding auxiliary control circuit; the auxiliary control circuit comprises a frequency converter fault delay switching bypass circuit, a bypass manual and automatic control circuit and a bypass overload signal circuit which are connected in parallel.

In an embodiment, the frequency converter fault time-delay switching bypass circuit includes a coil of the first time-delay relay 1KT and a coil of the third normally open contact 3KA3 of the third intermediate relay 3KA connected in series, and a coil of the first normally open contact 1KT1 of the first time-delay relay 1KT connected in series and a coil of the seventh intermediate relay 7KA connected in parallel to both ends of the coil of the third normally open contact 3KA of the third intermediate relay 3KA and the coil of the first time-delay relay 1KT connected in series; the coil of the second delay relay 2KT is connected in parallel with the two ends of the coil of the seventh intermediate relay 7 KA; the two ends of a first normally open contact 1KT1 of the first time delay relay 1KT are connected with a first normally open contact 7KA1 of a seventh intermediate relay 7KA in parallel; the coil of the second delay relay 2KT is connected in parallel with the first normally open contact 7KA1 of the seventh intermediate relay 7 KA.

When the frequency converter fails or cannot be started, the third normally open contact 3KA3 of the third intermediate relay 3KA is electrified and closed, and at the moment, the second alternating current contactor 2KM and the fourth alternating current contactor 4KM in the main loop are cut off through the first delay relay 1KT, so that the main loop 120 is disconnected, and the bypass loop 110 supplies power to the variable-frequency motor.

The bypass manual automatic control circuit comprises a second change-over switch SA2, and a bypass manual control circuit and a bypass automatic control circuit which are electrically connected with the second change-over switch SA2 in parallel. By setting the second changeover switch SA2, the activation of the bypass loop can be selected manually or automatically in both directions.

In some examples, the bypass manual control circuit includes a second switch selector SS2, a second push button switch SF2, a first normally closed contact 8KA1 of an eighth intermediate relay 8KA, a second normally closed contact 5KA2 of a fifth intermediate relay 5KA, a first normally closed contact 1KM1 of a first ac contactor 1KM and a coil of a third ac contactor 3KM connected in parallel, and a first normally open contact 2KM1 of a second ac contactor 2KM connected in parallel at both ends of the second push button switch SF2 and a second running indicator lamp HR2 connected in parallel at both ends of the coil of the third ac contactor 3 KM; and the bypass automatic control circuit comprises a fifth normally open contact 1KA5 of the first intermediate relay 1KA and a first normally open contact 2KT1 of the second delay relay 2KT which are connected in series.

The auxiliary control circuit of the bypass loop can be switched to automatic or switched to manual by manual operation, namely, the automatic maintenance of the alternating current contactor coil 1KM can realize the function of stopping the motor of the manual and automatic bidirectional switching frequency converter, namely, the state of no power failure in the switching process is maintained, and the flexibility of manual and automatic bidirectional switching is greatly improved. The ac contactor 1KM of the forced cooling fan circuit may also be closed by manual control (the second push switch SF2 is pressed) or automatic delay, keeping the forced cooling fan motor powered.

The bypass overload signal circuit comprises a first normally open contact 2KH1 of a second thermal relay 2KH and coils of an eighth intermediate relay 8KA which are connected in series, and second fault indicator lamps HY2 which are connected in parallel at two ends of the coils of the eighth intermediate relay 8 KA. The operator may be alerted to bypass loop overload by the second fault indicator HY2 being illuminated.

In one embodiment, the inverter VFD includes a power input port R, S, T and a power output port U, V, W; the power input port R, S, T of the frequency converter is electrically connected with the mains supply through a second alternating current contactor 2KM and a main breaker QF1 which are connected in series; the power output port U, V, W of the frequency converter is electrically connected to the variable frequency motor through the fourth ac contactor 4 KM. When the mains supply is connected, the main breaker QF1, the second alternating current contactor 2KM and the fourth alternating current contactor 4KM of the main loop are communicated, and current enters the power input port R, S, T of the frequency converter through the main breaker QF1 and the second alternating current contactor 2KM of the main loop, flows to the power output port U, V, W of the frequency converter and is output to the fourth alternating current contactor 4KM to supply power to the variable frequency motor.

In an embodiment, the frequency converter further comprises a starting contact port, an analog input port, an analog output port and a grounding port; the starting contact port is connected with a first normally-closed contact 1KM1 of the first alternating-current contactor 1KM in parallel; the analog input port is connected with a 4-20mA input circuit in parallel; the analog output port is connected with a 4-20mA output circuit in parallel; the ground port is grounded. The frequency converter is started through the control of the starting contact port so as to adjust the rotating speed of the variable frequency motor, and energy waste is avoided.

It is emphasized that: the control system of the frequency converter provided by the utility model is a hardware system, and any software technology update is not in the protection scope of the utility model. A frequency converter control system according to the utility model may be used alone or in combination with existing software or programs, but the utility model itself does not involve any software technology updates.

In an embodiment, the utility model further provides a frequency converter, which comprises a frequency converter control system.

In summary, the present utility model provides a frequency converter control system and a frequency converter applied thereto, where the frequency converter control system includes a frequency conversion loop and a forced cooling fan loop; the input end of the variable frequency loop is electrically connected with the mains supply, and the output end of the variable frequency loop is electrically connected with the variable frequency motor; the input end of the forced cooling fan loop is electrically connected with the commercial power, and the output end of the forced cooling fan loop is electrically connected with the forced cooling fan motor; the frequency conversion circuit comprises a frequency conversion circuit, a main circuit breaker, a parallel main circuit and a bypass circuit, wherein the main circuit breaker is electrically connected between an input end and an output end of the frequency conversion circuit, and the parallel main circuit and the bypass circuit are electrically connected with the main circuit breaker. According to the utility model, the main loop and the bypass loop are arranged, so that when the frequency converter fails, the frequency converter can be switched to the bypass loop to supply power to the frequency conversion motor; based on the self-holding of the alternating current contactor coil, the functions of manual and automatic bidirectional switching and no shutdown of the frequency converter motor can be realized; under the condition that the forced cooling fan is stopped or the temperature of the coil of the variable frequency motor is too high, the system can interlock the stop of the variable frequency motor so as to protect the variable frequency water pump or the fan. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present utility model and its effectiveness, and are not intended to limit the utility model. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the utility model. Accordingly, it is intended that all equivalent modifications and variations of the utility model be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims (11)

1. A frequency converter control system, comprising: a frequency conversion loop and a forced cooling fan loop;

The input end of the variable frequency loop is electrically connected with the mains supply, and the output end of the variable frequency loop is electrically connected with the variable frequency motor; the input end of the forced cooling fan loop is electrically connected with the commercial power, and the output end of the forced cooling fan loop is electrically connected with the forced cooling fan motor;

A main circuit breaker, a main circuit and a bypass circuit which are electrically connected in parallel and are electrically connected with the main circuit breaker are electrically connected between the input end and the output end of the variable frequency circuit; and a branch breaker, a first alternating current contactor and a first thermal relay are connected in series between the input end and the output end of the forced cooling fan loop.

2. The inverter control system of claim 1 wherein the main circuit comprises a second ac contactor, an inverter, and a fourth ac contactor in series; and the bypass loop includes a third ac contactor and a second thermal relay in series.

3. The frequency converter control system according to claim 2, wherein the main loop is provided with a corresponding main control circuit; the main control circuit comprises a live wire and a zero wire; the live wire is connected with at least one fuse; the live wire is provided with a power circuit, a manual and automatic switching circuit, a frequency converter fault output circuit, a frequency converter state output circuit, a fan starting and frequency converter motor linkage circuit, a frequency conversion main loop contactor linkage circuit, a frequency converter fault indication circuit, a frequency converter state indication circuit, a frequency converter motor overheat signal circuit and a fan overload circuit which are connected in parallel through the fuse and the zero line; the frequency converter fault output circuit and the frequency converter state output circuit are respectively and electrically connected with the frequency converter.

4. A frequency converter control system according to claim 3, comprising:

the power supply circuit comprises at least one power supply indicator lamp;

The manual automatic switching circuit comprises a first change-over switch; the first transfer switch is connected with and controls the starting unit and the stopping unit; the starting unit consists of a manual starting circuit and an automatic starting circuit which are connected in parallel; the stopping unit consists of a manual stopping circuit and an automatic stopping circuit which are connected in parallel;

the frequency converter fault output circuit comprises a coil of a third intermediate relay electrically connected with a fault output end of the frequency converter;

The frequency converter state output circuit comprises a coil of a fourth intermediate relay electrically connected with the running state output end of the frequency converter;

The fan starting and variable frequency motor linkage circuit comprises a first normally-open contact of a first intermediate relay, a first normally-closed contact of a second intermediate relay, a first normally-closed contact of a fifth intermediate relay, a first normally-closed contact of a sixth intermediate relay, coils of a first alternating-current contactor, a second normally-open contact of the first alternating-current contactor, which is connected in parallel with two ends of the first normally-open contact of the first intermediate relay, and operation indicator lamps, which are connected in parallel with two ends of the coils of the first alternating-current contactor;

The frequency conversion main loop contactor interlocking circuit comprises a sixth normally-open contact of a first intermediate relay, a second normally-closed contact of a seventh intermediate relay, a second normally-closed contact of a third alternating-current contactor and coils of a second alternating-current contactor which are connected in series, and a coil of a fourth alternating-current contactor and a third running indicator lamp which are respectively connected in parallel at two ends of the coil of the second alternating-current contactor; the coil of the fourth alternating current contactor is connected with the third running indicator lamp in parallel;

The frequency converter fault indication circuit comprises a first normally open contact and a fault indication lamp of a third intermediate relay which are connected in series;

the frequency converter state indicating circuit comprises a first normally open contact of a fourth intermediate relay and the running indicator lamp which are connected in series;

The variable frequency motor overheat signal circuit comprises a variable frequency motor internal temperature switch and a coil of a fifth intermediate relay which are connected in series, and fault indicator lamps connected in parallel at two ends of the coil of the fifth intermediate relay;

the fan overload circuit comprises a first normally open contact of a first thermal relay and a coil of a sixth intermediate relay which are connected in series, and fault indicator lamps connected in parallel at two ends of the coil of the sixth intermediate relay.

5. The inverter control system of claim 4 wherein the manual start circuit comprises a first push button switch and a coil of a first intermediate relay in series; the automatic starting circuit comprises a PLC starting switch; the manual stopping circuit comprises a second button switch; the automatic stopping circuit comprises a PLC stopping switch and a coil of a second intermediate relay which are connected in series.

6. The frequency converter control system according to claim 2, wherein the bypass loop is provided with a corresponding auxiliary control circuit; the auxiliary control circuit comprises a frequency converter fault delay switching bypass circuit, a bypass manual and automatic control circuit and a bypass overload signal circuit which are connected in parallel.

7. The inverter control system of claim 6, comprising:

The frequency converter fault delay switching bypass circuit comprises a third normally open contact of a third intermediate relay and a coil of a first delay relay which are connected in series, and a first normally open contact of the first delay relay and a coil of a seventh intermediate relay which are connected in series and connected in parallel at two ends of the third normally open contact of the third intermediate relay and the coil of the first delay relay which are connected in series; the coil of the second delay relay is connected in parallel with the two ends of the coil of the seventh intermediate relay; the two ends of the first normally open contact of the first delay relay are connected with the first normally open contact of the seventh intermediate relay in parallel; the coil of the second delay relay is connected with the first normally open contact of the seventh intermediate relay in parallel;

The bypass manual automatic control circuit comprises a second change-over switch, a bypass manual control circuit and a bypass automatic control circuit which are electrically connected with the second change-over switch in parallel;

The bypass overload signal circuit comprises a first normally open contact of a second thermal relay and coils of an eighth intermediate relay which are connected in series, and second fault indicator lamps which are connected in parallel at two ends of the coils of the eighth intermediate relay.

8. The inverter control system of claim 7, comprising:

The bypass manual control circuit comprises a second switch selector, a second button switch, a first normally-closed contact of an eighth intermediate relay, a second normally-closed contact of a fifth intermediate relay, a first normally-closed contact of a first alternating-current contactor, a coil of a third alternating-current contactor, a first normally-open contact of a second alternating-current contactor connected in parallel at two ends of the second button switch, and a second operation indicator lamp connected in parallel at two ends of the coil of the third alternating-current contactor in series;

And the bypass automatic control circuit comprises a fifth normally open contact of the first intermediate relay and a first normally open contact of the second delay relay which are connected in series.

9. The frequency converter control system of claim 2 or 4, wherein the frequency converter comprises a power input port R, S, T and a power output port U, V, W; the power input port R, S, T of the frequency converter is electrically connected with the mains supply through a second alternating-current contactor and a main breaker which are connected in series; the power output port U, V, W of the frequency converter is electrically connected to the variable frequency motor through the fourth ac contactor.

10. The inverter control system of claim 9, wherein the inverter further comprises a start-up junction port, an analog input port, an analog output port, a ground port; the starting contact port is connected with a first normally-closed contact of the first alternating-current contactor in parallel; the analog input port is connected with a 4-20mA input circuit in parallel; the analog output port is connected with a 4-20mA output circuit in parallel; the ground port is grounded.

11. A frequency converter, comprising: and a frequency converter control system.