Frequency converter control circuit and intelligent equipment

Abstract

The utility model discloses a frequency converter control circuit and an intelligent device. The frequency converter control circuit comprises a rectification unit and a bus capacitor connected with the rectification unit. The protection unit is connected with the rectification unit and is used for collecting an output signal of the rectification unit and generating a first level signal; the main control unit is used for outputting a second level signal; the standby protection unit is connected with the protection unit in parallel and is also connected with the main control unit; the standby protection unit is used for generating a third level signal according to the level signal of the main control unit; the soft start unit is respectively connected with the rectification unit, the bus capacitor, the protection unit, the main control unit and the standby protection unit; and the soft start unit is used for switching on and off according to the first level signal / the third level signal and the second level signal. According to the utility model, through the protection unit or the standby protection unit, the soft start unit cannot be immediately conducted when being instantly powered off, so that the charging current in the circuit is reduced, and power components in the circuit are prevented from being damaged due to overlarge charging current.

Description

TECHNICAL FIELD

[0001] The utility model relates to electronic circuit technical field especially, relates to a frequency converter control circuit and intelligent equipment. BACKGROUND

[0002] The complete frequency converter is mainly composed of rectifier bridge, bus capacitor and inverter three parts. The bus capacitor plays an important role in stabilizing voltage and improving system reliability. When the frequency converter is powered on, the bus capacitor is charged first, according to the relationship between the current flowing through the bus capacitor and the voltage across the bus capacitor When the voltage across the bus capacitor changes greatly, the charging current will also increase. In order to prevent the charging current from being too large to damage the device when the power is turned on, a soft start circuit is usually added in front of the bus capacitor, such as Figure 1 As shown, the soft start circuit includes a resistor R1', a relay K' and a switch tube G1', a resistor R1' is provided between the bus capacitor and the rectifier unit, and then the two ends of the resistor R1' are connected with the two contact pins of the relay K' respectively; the collector of the switch tube G1' is connected with the coil pin of the relay K' and then connected with the VCC pin, the gate of the switch tube G1' is connected with the main control chip, and the emitter of the switch tube G1' is grounded.

[0003] Due to the voltage division effect of the resistor R1', the voltage across the bus capacitor will not increase instantaneously when the power is turned on, thereby achieving the effect of limiting the charging current. When the bus voltage is greater than the first set value, the main control chip applies a high-level control signal between the gate and the emitter of the switch tube G1', the switch tube G1' is turned on, and then the relay K' is closed, thereby bypassing the resistor R1', thereby reducing the power loss in operation. When the bus voltage is less than the second set value, the main control chip applies a low-level control signal between the gate and the emitter of the switch tube G1', the switch tube G1' is turned off, the relay K' is opened, and the resistor R1' is again connected in series with the bus capacitor, thereby preventing the charging current from being too large when the voltage is restored.

[0004] However, in most cases, in order to reduce false alarms, the second set value is set to be small. If the voltage does not flash for a long time, the relay K' has not been disconnected before the power is turned on again, which will also cause the charging current to be too large to damage the components and cannot effectively protect the rear-end power devices.

[0005] Therefore, how to provide a control circuit that can be quickly cut off when the power supply is instantaneously disconnected and powered on is a problem to be solved. UTILITY MODEL CONTENTS

[0006] The utility model provides a frequency converter control circuit and intelligent equipment for solving the problem that the control circuit cannot be quickly cut off when the power supply is instantaneously disconnected and powered on in the prior art.

[0007] The utility model discloses a technical scheme for a frequency converter control circuit, comprising a rectifier unit and a bus capacitor connected with the rectifier unit; further comprising:

[0008] A protection unit connected with the rectifier unit; the protection unit is used for collecting the output signal of the rectifier unit and generating a first level signal;

[0009] A main control unit for outputting a second level signal;

[0010] A backup protection unit connected in parallel with the protection unit, and the backup protection unit is also connected with the main control unit; the protection unit is used for generating a third level signal according to the level signal of the main control unit;

[0011] A soft start unit connected with the rectifier unit, bus capacitor, protection unit, main control unit and backup protection unit respectively, and the soft start unit is used for conducting or breaking according to the first level signal / third level signal and second level signal.

[0012] Further, the protection unit comprises a third resistor, a fourth resistor, a fifth resistor and a second power device;

[0013] The first end of the third resistor is connected with the first output end of the rectifier unit and the input end of the soft start unit respectively, the second end of the third resistor is connected with the first end of the fourth resistor and the gate of the second power device respectively, the emitter of the second power device is grounded, the collector of the second power device is connected with the output end of the backup protection unit and the first end of the fifth resistor respectively, and the second end of the fifth resistor is connected with the VCC pin;

[0014] The second end of the fourth resistor is connected with the second output end of the rectifier unit.

[0015] Further, the backup protection unit comprises a third power device, the gate of the third power device is connected with the first output end of the main control unit, the emitter of the third power device is grounded, and the collector of the third power device is connected with the output end of the protection unit.

[0016] Further, the third resistor and the fourth resistor are both provided with a plurality of, and the plurality of third resistors and the plurality of fourth resistors are both arranged in series respectively.

[0017] Further, when the frequency converter control circuit is powered off and powered on instantaneously, the first level signal output by the protection unit is a low level signal, the second level signal output by the main control unit is a low level signal, and the soft start unit is in an off state.

[0018] Further, when the frequency converter control circuit is powered off and powered on instantaneously, the main control unit outputs a high level signal to the backup protection unit, the third level signal output by the backup protection unit is a low level signal, the second level signal output by the main control unit is a low level signal, and the soft start unit is in an off state.

[0019] Further, the soft start unit comprises a first resistor, a second resistor, a first power device and a charging relay.

[0020] The first end of the first resistor and the common contact of the charging relay are connected to the input end of the protection unit, and the second end of the first resistor and the normally closed contact of the charging relay are connected to the positive pole of the bus capacitor.

[0021] The first coil pin of the charging relay is connected to the collector of the first power device and the first end of the second resistor, respectively, the gate of the first power device is connected to the second output end of the main control unit, and the emitter of the first power device is connected to the output end of the protection unit and the output end of the backup protection unit, respectively.

[0022] The second end of the second resistor and the first coil pin of the charging relay are used for connecting the VCC pin.

[0023] Further, the first resistor has a plurality of first resistors, and the plurality of first resistors are arranged in series.

[0024] Further, the frequency converter control circuit further comprises an inverter unit, and the inverter unit comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm each composed of two switching tubes.

[0025] The rectifier unit comprises a first bridge arm and a second bridge arm each composed of two rectifier diodes.

[0026] The midpoint of the first bridge arm and the midpoint of the second bridge arm are used for connecting to an alternating current power grid; one end of the first bridge arm and one end of the second bridge arm are connected to the input end of the soft start unit, and the other end of the first bridge arm and the other end of the second bridge arm are connected to the negative pole of the bus capacitor.

[0027] The midpoint of the third bridge arm, the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm are used for connecting to a motor, respectively; the two ends of the third bridge arm, the two ends of the fourth bridge arm and the two ends of the fifth bridge arm are connected to the two ends of the bus capacitor, respectively.

[0028] An intelligent device, the intelligent device comprising the frequency converter control circuit.

[0029] Compared with the prior art, the utility model has at least the following beneficial effects:

[0030] The utility model discloses a protection unit or spare protection unit to the frequency converter control circuit protection, so even if the protection unit is damaged because of accidental situation, also has the spare protection unit to the frequency converter control circuit protection, and then makes the soft start unit instantaneous off power and can not immediately conduct, reduces the charging current in the frequency converter control circuit, prevents the condition that the power component in the frequency converter control circuit is damaged because of the charging current too big. BRIEF DESCRIPTION OF DRAWINGS

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the utility model belongs; the terms used in the specification of the application are only for the purpose of describing the specific embodiments and are not intended to limit the utility model; the terms "include" and "have" in the specification and claims of the utility model and the above description of drawings, and any modification thereof, are intended to cover the non-exclusive inclusion. The terms "first", "second" and the like in the specification and claims of the utility model or the above description of drawings are used to distinguish different objects, not to describe a specific order.

[0032] In order to more clearly illustrate the technical scheme in the embodiments of the utility model, the drawings needed to be used in the embodiments or prior art description will be briefly introduced below, 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 also be obtained according to these drawings without creative labor.

[0033] Figure 1 The circuit diagram of the control circuit of the frequency converter proposed in the background art;

[0034] Figure 2 The module block diagram of the frequency converter control circuit proposed in the utility model;

[0035] Figure 3 The circuit diagram of the frequency converter control circuit proposed in the utility model;

[0036] Figure 4 The circuit diagram of another frequency converter control circuit proposed in the utility model.

[0037] Reference signs:

[0038] 10, rectifier unit;

[0039] 20, protection unit;

[0040] 30, spare protection unit;

[0041] 40, master control unit;

[0042] 50, soft start unit;

[0043] 60, inverter unit;

[0044] 70, motor. DETAILED DESCRIPTION

[0045] In order to make the technical problems, technical schemes and beneficial effects to be solved by the utility model more clear and apparent, the utility model will be further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. Therefore, one feature mentioned in the specification will be used to explain one feature of one embodiment of the utility model, and it is not suggested that each embodiment of the utility model must have the explained feature. In addition, it should be noted that the specification describes many features. Although certain features can be combined together to show possible system designs, these features can also be used in other combinations that are not explicitly explained. Therefore, unless otherwise stated, the explained combination is not intended to be limited.

[0046] The principle and structure of the utility model will be described in detail below in combination with the drawings and embodiments.

[0047] In some embodiments, in order to ensure that the frequency converter control circuit can be quickly cut off when the power supply is powered on instantaneously, the soft start unit 50 is in the open state, the charging current is prevented from being too large to damage the components, the rear-end power device is effectively protected, and the like, Figure 2 As shown in the utility model, a frequency converter control circuit is provided, which comprises a rectifier unit 10 and a bus capacitor C connected with the rectifier unit 10; and further comprises:

[0048] A protection unit 20 is connected with the rectifier unit 10; the protection unit 20 is used for collecting the output signal of the rectifier unit 10 and generating a first level signal;

[0049] A master control unit 30 is used for outputting a second level signal; the master control unit 30 is preferably a master control MCU.

[0050] A backup protection unit 40 is connected with the protection unit 20 in parallel, and the backup protection unit 40 is further connected with the master control unit 30; the protection unit 20 is used for generating a third level signal according to the level signal of the master control unit 30;

[0051] A soft start unit 50 is connected with the rectifier unit 10, the bus capacitor C, the protection unit 20, the main control unit 30 and the backup protection unit 40 respectively, and is used to turn on or off according to the first level signal / third level signal and the second level signal.

[0052] It should be noted that the output signal of the rectifier unit 10 in the embodiment is preferably an output voltage.

[0053] When the frequency converter control circuit is powered on (input voltage > 0) and normally operated, the output voltage of the rectifier unit 10 is normally output, the main control unit 30 detects whether the bus voltage is greater than the second preset voltage, and if the bus voltage is greater than the second preset voltage, the protection unit 20 normally works, at this time, the protection unit 20 generates a high-level first level signal according to the output voltage of the rectifier unit 10 and outputs it to the soft start unit 50, and the main control unit 30 outputs a high-level signal to the soft start unit 50 after the bus voltage of the bus capacitor C reaches the first preset voltage, and the soft start unit 50 is turned on after receiving the above two signals, thereby reducing the power loss in the operation of the frequency converter control circuit; if the output voltage of the rectifier unit 10 is instantaneously powered off (the instantaneously powered off in the embodiment refers to that the power is turned off and then turned on again instantly, and the same applies hereinafter), the main control unit 30 outputs a second level signal to the soft start unit 50, which is a low-level signal, so that the soft start unit 50 cannot be turned on immediately when it is instantaneously powered off, thereby reducing the charging current in the frequency converter control circuit to prevent the power components in the frequency converter control circuit from being damaged due to excessive charging current.

[0054] If the bus voltage is not greater than the second preset voltage, the protection unit 20 is damaged, the main control unit 30 outputs a high-level signal to the backup protection unit 40 to turn on the backup protection unit 40, and then the main control unit 30 outputs a high-level signal to the soft start unit 50 after the bus voltage of the bus capacitor C reaches the first preset voltage, so that the soft start unit 50 is turned on to reduce the power loss in the operation of the frequency converter control circuit; if the output voltage of the rectifier unit 10 is instantaneously powered off, the main control unit 30 outputs a low-level second level signal to the backup protection unit 40, and then the backup protection unit 40 is in an off state, thereby making the soft start unit 50 also in an off state, so that the soft start unit 50 cannot be turned on immediately when it is instantaneously powered off, thereby reducing the charging current in the frequency converter control circuit to prevent the power components in the frequency converter control circuit from being damaged due to excessive charging current.

[0055] Therefore, the utility model discloses a protection unit 20 or spare protection unit 40 to the frequency converter control circuit protection, so even if the protection unit 20 is damaged due to accidental circumstances, also have spare protection unit 40 to the frequency converter control circuit protection, and then make soft start unit 50 instantaneous power on and can not immediately conduct, reduce the charging current in the frequency converter control circuit, to prevent the case of charging current too large damage power components in the frequency converter control circuit.

[0056] Of course, it can also be directly selected to activate the spare protection unit 40 to protect the frequency converter control circuit, at this time, the protection unit 20 is not activated or de-energized, which is not limited.

[0057] In some embodiments, as shown in the figure, the embodiment proposes a specific circuit structure of the soft start unit 50: Figure 3

[0058] The soft start unit 50 includes a first resistor R1, a second resistor R2, a first power device G1 and a charging relay K.

[0059] The first end of the first resistor R1 and the common contact of the charging relay K are connected with the input end of the protection unit 20, and the second end of the first resistor R1 and the normally closed contact of the charging relay K are connected with the positive pole of the bus capacitor C.

[0060] The first coil pin of the charging relay K is connected with the collector of the first power device G1 and the first end of the second resistor R2 respectively, the gate of the first power device G1 is connected with the second output end of the main control unit 30, and the emitter of the first power device G1 is connected with the output end of the protection unit 20 and the output end of the spare protection unit 40 respectively.

[0061] The second end of the second resistor R2 and the first coil pin of the charging relay K are used for connecting the VCC pin.

[0062] It should be noted that the first power device G1 is an insulated gate bipolar transistor, a field effect transistor, a bipolar transistor, a thyristor or other controllable power device, which is not limited. The VCC pin in the embodiment is a power supply pin, which is used to provide working voltage for the frequency converter control circuit. And the second resistor R2 is a pull-up resistor, so that the second resistor R2 can ensure that the level of the collector of the first power device G1 connected with the second resistor R2 is high when the first power device G1 is disconnected.

[0063] ​Thus when the frequency converter control circuit is powered on (input voltage > 0) and normally running, the output voltage of the rectifier unit 10 is normally output, the bus voltage is detected by the main control unit 30 whether it is greater than the second preset voltage, if the bus voltage is greater than the second preset voltage, the protection unit 20 will generate a high level first level signal according to the output voltage of the rectifier unit 10 and output to the emitter of the first power device G1, the main control unit 30 will output a high level signal to the gate of the first power device G1 after the bus voltage of the bus capacitor C reaches the first preset voltage, the first power device G1 is turned on due to the voltage difference between the emitter and the gate, the charging relay K is attracted (the coil of the charging relay K is powered, the contacts of the charging relay K are closed), so that the charging relay K bypasses the first resistor R1, thereby reducing the power loss of the frequency converter control circuit in operation. When the frequency converter control circuit is powered off, the protection unit 20 is in an open state, at this time no matter what signal is input to the gate of the first power device G1, the charging relay K is disconnected (the coil of the charging relay K will not be powered, the contacts of the charging relay K are open and remain in an open state), the first resistor R1 is connected in series with the bus capacitor C; when the frequency converter control circuit is powered off and powered on instantaneously, the protection unit 20 will change from the open state to the conductive state, the protection unit 20 will output a low level signal to the emitter of the first power device G1, and the gate of the first power device G1 before the power failure remains high level, there is a voltage difference between the gate and the emitter of the first power device G1, the first power device G1 is momentarily turned on, the emitter and the collector of the first power device G1 are both low level, the charging relay K is attracted, at this time in order to prevent the first resistor R1 from being bypassed and not playing a current limiting role, the main control unit 30 will output a low level signal to the gate of the first power device G1, so that when the frequency converter control circuit is powered on instantaneously, the first power device G1 cannot be immediately turned on, the charging relay K is quickly disconnected, the first resistor R1 is connected in series with the bus capacitor C, so as to reduce the charging current in the frequency converter control circuit, so as to prevent the power components in the frequency converter control circuit from being damaged due to excessive charging current. Until the main control unit 30 detects that the bus voltage of the bus capacitor C reaches the first preset voltage (the first preset voltage is greater than the second preset voltage), the charging relay K is attracted.

[0064] If the bus voltage is not greater than the second preset voltage, the protection unit 20 is damaged, the main control unit 30 outputs a high level signal to the standby protection unit 40, turns on the standby protection unit 40, and then the main control unit 30 outputs a high level signal to the gate of the first power device G1 when the bus voltage of the bus capacitor C reaches the first preset voltage, so that the first power device G1 is turned on, the charging relay K is attracted, and the charging relay K bypasses the first resistor R1, thereby reducing the power loss in the operation of the frequency converter control circuit; if the output voltage of the rectifier unit 10 is instantaneously interrupted, at this time the main control unit 30 outputs a low level second level signal to the standby protection unit 40, and then the standby protection unit 40 is in an open state, thereby making the soft start unit 50 also in an open state, so that the soft start unit 50 cannot be turned on immediately when the soft start unit 50 is instantaneously interrupted, reducing the charging current in the frequency converter control circuit, to prevent the power components in the frequency converter control circuit from being damaged due to excessive charging current.

[0065] In some embodiments, in order to better protect the frequency converter control circuit, as shown in FIG. 1, the present embodiment proposes a circuit structure of the protection unit 20: Figure 3

[0066] The protection unit 20 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a second power device G2.

[0067] The first end of the third resistor R3 is connected with the first output end of the rectifier unit 10 and the first end of the first resistor R1 respectively, the second end of the third resistor R3 is connected with the first end of the fourth resistor R4 and the gate of the second power device G2 respectively, the emitter of the second power device G2 is grounded, the collector of the second power device G2 is connected with the output end of the standby protection unit 40 and the first end of the fifth resistor R5 respectively, and the second end of the fifth resistor R5 is connected with the VCC pin.

[0068] The second end of the fourth resistor R4 is connected with the second output end of the rectifier unit 10.

[0069] It should be noted that the second power device G2 is an insulated gate bipolar transistor, a field effect transistor, a bipolar transistor, a thyristor or other controllable power device, which is not limited here. The fourth resistor R4 is a pull-up resistor, so that the fourth resistor R4 can ensure that the level of the collector of the second power device G2 connected with the fourth resistor R4 is high when the second power device G2 is disconnected.

[0070] ​Thus when the frequency converter control circuit is powered on (input voltage > 0) and normally running, the output voltage of the rectifier unit 10 is normally output, the bus voltage is detected by the main control unit 30 whether it is greater than the second preset voltage, if the bus voltage is greater than the second preset voltage, at this time the bus voltage is divided by the third resistor R3 and the fourth resistor R4, a high level signal is applied between the gate and the emitter of the second power device G2, so that the second power device G2 is turned on, the emitter and the collector of the second power device G2 are both low level; and the collector of the second power device G2 is connected with the emitter of the first power device G1, resulting in the emitter of the first power device G1 also being low level, at the same time the main control unit 30 will output a high level signal to the gate of the first power device G1 according to the bus voltage of the bus capacitor C reaching the first preset voltage, so as to cause the first power device G1 to be turned on, the charging relay K is attracted, so that the charging relay K bypasses the first resistor R1, thereby reducing the power loss in the running of the frequency converter control circuit.

[0071] When the power supply of the frequency converter control circuit is interrupted, the gate of the second power device G2 has no voltage level, causing the second power device G2 to be turned off (in this way, when the power supply of the frequency converter control circuit is interrupted, the second power device G2 is automatically turned off, the response speed is fast, and the damage of the power device caused by the instantaneous interruption of the power supply can be minimized). The collector of the second power device G2 is pulled up to a high level by the fifth resistor R5, and the first power device G1 is also turned off. The collector of the first power device G1 is pulled up to a high level by the second resistor R2, the charging relay K is turned off, and the first resistor R1 is connected to the bus capacitor C again, thereby reducing the influence of the charging current on the rear-end power device of the frequency converter control circuit (equivalent to the power device in the inverter unit 60). When the power supply of the frequency converter control circuit is instantaneous, the bus voltage is divided by the third resistor R3 and the fourth resistor R4, and a high-level signal is applied between the gate and the emitter of the second power device G2 to turn on the second power device G2. At this time, the emitter and the collector of the second power device G2 are both at a low level. Since the emitter of the first power device G1 is connected to the collector of the second power device G2, the emitter of the first power device G1 is also at a low level. Before the power supply is interrupted, the gate of the first power device G1 remains at a high level. Therefore, there is a voltage difference between the gate and the emitter of the first power device G1, and the first power device G1 is turned on instantaneously. The emitter and the collector of the first power device G1 are both at a low level, and the charging relay K is attracted. To prevent the first resistor R1 from being bypassed and not playing a current-limiting role, the main control unit 30 outputs a low-level signal to the gate of the first power device G1. In this way, when the power supply of the frequency converter control circuit is instantaneous, the first power device G1 cannot be turned on immediately, the charging relay K is quickly turned off, and the first resistor R1 is connected in series with the bus capacitor C to reduce the charging current in the frequency converter control circuit and prevent the damage of the components in the frequency converter control circuit caused by the excessive charging current. Until the main control unit 30 detects that the bus voltage of the bus capacitor C reaches the first preset voltage, the charging relay K is attracted.

[0072] In some embodiments, to better protect the frequency converter control circuit, as shown in FIG. 6, the present embodiment proposes a circuit structure of the backup protection unit 40. Figure 3

[0073] The backup protection unit 40 includes a third power device G3. The gate of the third power device G3 is connected to the first output end of the main control unit 30. The emitter of the third power device G3 is grounded. The collector of the third power device G3 is connected to the collector of the second power device G2 and the first end of the fifth resistor R5.

[0074] ​It should be noted that the third power device G3 is an insulated gate bipolar transistor, a field effect transistor, a bipolar transistor, a thyristor or other controllable power device, which is not limited here.

[0075] Thus when the frequency converter control circuit is powered on (input voltage > 0) and normally operated, the output voltage of the rectifier unit 10 is normally output, the bus voltage is detected by the main control unit 30 whether it is greater than the second preset voltage, if the bus voltage is not greater than the second preset voltage, then the protection unit 20 is damaged, at this time the main control unit 30 will output a high level signal to the gate of the third power device G3 to turn on the third power device G3, the emitter and collector of the third power device G3 are low level; and the collector of the third power device G3 is connected with the emitter of the first power device G1, resulting in that the emitter of the first power device G1 is also low level, then the main control unit 30 outputs a high level signal to the gate of the first power device G1 according to the bus voltage of the bus capacitor C reaching the first preset voltage, so that the first power device G1 is turned on, the charging relay K is attracted, and the first resistor R1 is bypassed by the charging relay K, thereby reducing the power loss in the operation of the frequency converter control circuit.

[0076] When the output voltage of the rectifier unit 10 is powered off, the gate of the third power device G3 has no voltage level, causing the third power device G3 to be turned off (in this way, when the frequency converter control circuit is powered off, the third power device G3 will be automatically turned off, the response speed is fast, and the damage to the power device caused by the instantaneous power-off can be minimized). The collector of the third power device G3 is pulled up to a high level by the fifth resistor R5, and the first power device G1 is also turned off, the collector of the first power device G1 is pulled up to a high level by the second resistor R2, the charging relay K is turned off, and the first resistor R1 is reconnected to the bus capacitor C, thereby reducing the impact of the charging current on the back-end power device of the frequency converter control circuit (equivalent to the power device in the inverter unit 60). When the frequency converter control circuit is powered on instantaneously, the main control unit 30 outputs a high-level signal to the gate of the third power device G3 to turn on the third power device G3, and at this time, the emitter and collector of the third power device G3 are both at a low level. Since the emitter of the first power device G1 is connected to the collector of the third power device G3, the emitter of the first power device G1 is also at a low level. Before the power-off, the gate of the first power device G1 remains at a high level, so there is a voltage difference between the gate and the emitter of the first power device G1. The first power device G1 is turned on instantaneously, the emitter and collector of the first power device G1 are both at a low level, and the charging relay K is attracted. At this time, to prevent the first resistor R1 from being bypassed and not playing a current-limiting role, the main control unit 30 outputs a low-level signal to the gate of the first power device G1. In this way, when the frequency converter control circuit is powered on instantaneously, the first power device G1 cannot be immediately turned on, the charging relay K is quickly turned off, and the first resistor R1 is connected in series with the bus capacitor C to reduce the charging current in the frequency converter control circuit and prevent the damage to the components in the frequency converter control circuit caused by excessive charging current. Until the main control unit 30 detects that the bus voltage of the bus capacitor C reaches the first preset voltage, the charging relay K is attracted.

[0077] In other embodiments, to ensure better voltage division of the bus voltage and improve the stability of the frequency converter control circuit, as shown in Figure 4 The third resistor R3 and the fourth resistor R4 are each provided with a plurality of resistors, and the plurality of third resistors R3 and the plurality of fourth resistors R4 are each connected in series.

[0078] In some embodiments, when the frequency converter control circuit is powered off and powered on instantaneously, the first level signal output by the protection unit 20 is a low-level signal, the second level signal output by the main control unit 30 is a low-level signal, and the soft start unit 50 is in an off state.

[0079] In this way, when the protection unit 20 continuously outputs the first level signal to the soft start unit 50, the continuity and stability of the frequency converter control circuit in the normal working state are ensured. The conduction of the first power device G1 and the second power device G2 and the attraction of the charging relay K ensure the normal operation of the frequency converter control circuit. When the frequency converter control circuit is instantaneously powered off and powered on, the frequency converter control circuit can quickly respond, the first power device G1 and the third power device G3 are disconnected, and the charging relay K is disconnected, so as to prevent misoperation or damage caused by signal interruption and improve the reliability and safety of the frequency converter control circuit.

[0080] In some embodiments, when the frequency converter control circuit is powered off and instantaneously powered on, the main control unit 30 outputs a high level signal to the backup protection unit 40, the third level signal output by the backup protection unit 40 is a low level signal, the second level signal output by the main control unit 30 is a low level signal, and the soft start unit 50 is in a disconnected state.

[0081] In this way, when the backup protection unit 40 continuously outputs the third level signal to the soft start unit 50, the continuity and stability of the frequency converter control circuit in the normal working state are ensured. The conduction of the first power device G1 and the third power device G3 and the attraction of the charging relay K ensure the normal operation of the frequency converter control circuit. When the frequency converter control circuit is instantaneously powered off and powered on, the frequency converter control circuit can quickly respond, the first power device G1 and the third power device G3 are disconnected, and the charging relay K is disconnected, so as to prevent misoperation or damage caused by signal interruption and improve the reliability and safety of the frequency converter control circuit.

[0082] In other embodiments, in order to better limit the charging current of the frequency converter control circuit when the charging relay K is attracted, the first resistor R1 is provided as shown in Figure 4 In this way, the first resistor R1 is provided in multiple and is arranged in series.

[0083] In some embodiments, in order to ensure that the frequency converter control circuit can rectify the AC power from the power grid into DC power, the charging current of the frequency converter control circuit can stably supply power to the motor 70 and realize frequency conversion control of the motor 70, the frequency converter control circuit further comprises an inverter unit 60, and the inverter unit 60 comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm each composed of two switching tubes. Figure 3

[0084] The rectifier unit 10 comprises a first bridge arm and a second bridge arm each composed of two rectifier diodes.

[0085] ​The midpoint of the first bridge arm and the midpoint of the second bridge arm are used for being connected with an alternating current power grid; one end of the first bridge arm and one end of the second bridge arm are connected with the input end of the soft start unit 50, and the other end of the first bridge arm and the other end of the second bridge arm are connected with the negative pole of the bus capacitor C;

[0086] The midpoint of the third bridge arm, the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm are respectively used for being connected with the motor 70; the two ends of the third bridge arm, the two ends of the fourth bridge arm and the two ends of the fifth bridge arm are respectively connected with the two ends of the bus capacitor C.

[0087] In some embodiments, the utility model also proposes an intelligent device, the intelligent device includes the frequency converter control circuit above-mentioned.

[0088] Specifically, the circuit structure of the frequency converter control circuit in the embodiment is as follows:

[0089] The rectification unit 10 includes the first bridge arm and the second bridge arm which are respectively composed of two rectification diodes; the protection unit 20 includes the third resistance R3, the fourth resistance R4, the fifth resistance R5 and the second power device G2; the standby protection unit 40 includes the third power device G3; the soft start unit 50 includes the first resistance R1, the second resistance R2, the first power device G1 and the charging relay K; the inversion unit 60 includes the third bridge arm, the fourth bridge arm and the fifth bridge arm which are respectively composed of two switch tubes;

[0090] The midpoint of the first bridge arm and the midpoint of the second bridge arm are used for being connected with an alternating current power grid; the first end of the first bridge arm, the first end of the second bridge arm, the common contact of the charging relay K and the first end of the third resistance R3 are connected with the first end of the first resistance R1, the second end of the first resistance R1 and the normally closed contact of the charging relay K are connected with the positive pole of the bus capacitor C; the other end of the first bridge arm, the other end of the second bridge arm and the second end of the fourth resistance R4 are connected with the negative pole of the bus capacitor C;

[0091] The second end of the third resistance R3 is connected with the first end of the fourth resistance R4 and the gate of the second power device G2 respectively, the collector of the second power device G2 and the collector of the third power device G3 are connected with the first end of the fifth resistance R5, the collector of the third power device G3 is also connected with the emitter of the first power device G1, the collector of the first power device G1 is connected with the first coil pin of the charging relay K and the first end of the second resistance R2 respectively;

[0092] The midpoint of the third bridge arm, the midpoint of the fourth bridge arm and the midpoint of the fifth bridge arm are respectively used for being connected with the motor 70; the two ends of the third bridge arm, the two ends of the fourth bridge arm and the two ends of the fifth bridge arm are respectively connected with the two ends of the bus capacitor C.

[0093] The second end of the second resistor R2, the first coil pin of the charging relay K and the second end of the fifth resistor R5 are all connected to the VCC pin; the gate of the third power device G3 is connected to the first output end of the master control unit 30; the gate of the first power device G1 is connected to the second output end of the master control unit 30; the emitter of the second power device G2 and the emitter of the third power device G3 are both grounded.

[0094] When the intelligent device is powered on, the frequency converter control circuit is powered on (the input voltage > 0) and normally operated, the master control unit 30 detects whether the bus voltage is greater than the second preset voltage, if the bus voltage is greater than the second preset voltage, the protection unit 20 normally works, at this time the protection unit 20 will generate a high level first level signal according to the output voltage of the rectifier unit 10 and output to the soft start unit 50, at the same time the master control unit 30 will output a high level signal to the soft start unit 50 after the bus voltage of the bus capacitor C reaches the first preset voltage, and the soft start unit 50 is turned on after receiving the above two signals, thereby reducing the power loss in the operation of the frequency converter control circuit; if the output voltage of the rectifier unit 10 is instantaneously powered off, at this time the master control unit 30 will output a second level signal to the soft start unit 50, the second level signal is low, so that the soft start unit 50 cannot be immediately turned on when it is instantaneously powered off, reducing the charging current in the frequency converter control circuit, to prevent the power components in the frequency converter control circuit from being damaged by excessive charging current.

[0095] If the bus voltage is not greater than the second preset voltage, the protection unit 20 is damaged, the master control unit 30 will output a high level signal to the standby protection unit 40, turn on the standby protection unit 40, and then the master control unit 30 will output a high level signal to the soft start unit 50 after the bus voltage of the bus capacitor C reaches the first preset voltage, so that the soft start unit 50 is turned on, thereby reducing the power loss in the operation of the frequency converter control circuit; if the output voltage of the rectifier unit 10 is instantaneously powered off, at this time the master control unit 30 will output a low level second level signal to the standby protection unit 40, then the standby protection unit 40 is in the off state, and then the soft start unit 50 is also in the off state, so that the soft start unit 50 cannot be immediately turned on when it is instantaneously powered off, reducing the charging current in the frequency converter control circuit, to prevent the power components in the frequency converter control circuit from being damaged by excessive charging current.

[0096] Therefore, the utility model discloses a protection unit 20 or spare protection unit 40 to the frequency converter control circuit protection, so even if protection unit 20 is damaged due to accidental circumstances, also have spare protection unit 40 to the frequency converter control circuit spare protection, and then make soft start unit 50 instantaneous power on cannot immediately conduct, reduce the charging current in the frequency converter control circuit, prevent the condition that charging current is too large and damages the power component in the frequency converter control circuit, and then guarantee the normal operation of intelligent equipment.

[0097] Obviously, the above-described embodiments are only a part of the embodiments of the utility model, and are not all the embodiments, and the drawings give the preferred embodiments of the utility model, but do not limit the patent range of the utility model. The utility model can be realized in many different forms, and contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the utility model more thorough and comprehensive. Although the utility model is described in detail with reference to the foregoing embodiments, for those skilled in the art, the technical scheme recorded in the foregoing specific embodiments can be modified, or part of the technical features can be replaced equivalently. Any equivalent structure made by using the contents of the utility model specification and drawings, directly or indirectly used in other related technical fields, are also within the patent protection range of the utility model.

Claims

1. A frequency converter control circuit comprising a rectifying unit (10) and a bus capacitor connected to the rectifying unit (10); characterized in that, Also include: A protection unit (20) connected with the rectifier unit (10); the protection unit (20) is used to collect the output signal of the rectifier unit (10) and generate a first level signal; The main control unit (30) is used for outputting a second level signal; The standby protection unit (40) is connected with the protection unit (20) in parallel, and the standby protection unit (40) is also connected with the main control unit (30); the protection unit (20) is used to generate a third level signal according to the level signal of the main control unit (30); The soft start unit (50) is connected with the rectifier unit (10), bus capacitor, protection unit (20), main control unit (30) and standby protection unit (40) respectively; the soft start unit (50) is used for on-off according to the first level signal / third level signal and the second level signal.

2. The frequency inverter control circuit of claim 1, wherein, The protection unit (20) includes a third resistor, a fourth resistor, a fifth resistor and a second power device; The first end of the third resistor is connected with the first output end of the rectifier unit (10) and the input end of the soft start unit (50) respectively, the second end of the third resistor is connected with the first end of the fourth resistor and the gate of the second power device respectively, the emitter of the second power device is grounded, the collector of the second power device is connected with the output end of the standby protection unit (40) and the first end of the fifth resistor respectively, and the second end of the fifth resistor is connected with the VCC pin; The second end of the fourth resistor is connected with the second output end of the rectifier unit (10).

3. The frequency inverter control circuit of claim 1, wherein, The standby protection unit (40) includes a third power device, the gate of the third power device is connected with the first output end of the main control unit (30), the emitter of the third power device is grounded, and the collector of the third power device is connected with the output end of the protection unit (20).

4. The frequency inverter control circuit of claim 2, wherein, The third resistor and the fourth resistor are provided with a plurality of, and the plurality of third resistors and the plurality of fourth resistors are arranged in series respectively.

5. The frequency inverter control circuit of claim 1, wherein, When the frequency converter control circuit is powered off and powered on instantaneously, the first level signal output by the protection unit (20) is a low level signal, the second level signal output by the main control unit (30) is a low level signal, and the soft start unit (50) is in the off state.

6. The frequency inverter control circuit of claim 1, wherein, When the frequency converter control circuit is powered off and powered on instantaneously, the main control unit (30) outputs a high level signal to the standby protection unit (40), the third level signal output by the standby protection unit (40) is a low level signal, the second level signal output by the main control unit (30) is a low level signal, and the soft start unit (50) is in the off state.

7. The frequency inverter control circuit of claim 1, wherein, The soft start unit (50) includes a first resistor, a second resistor, a first power device and a charging relay; The first end of the first resistor and the common contact of the charging relay are connected with the input end of the protection unit (20), the second end of the first resistor and the normally closed contact of the charging relay are connected with the positive electrode of the bus capacitor; The first coil pin of the charging relay is connected with the collector of the first power device and the first end of the second resistor respectively, the gate of the first power device is connected with the second output end of the master control unit (30), and the emitter of the first power device is connected with the output end of the protection unit (20) and the output end of the backup protection unit (40) respectively. The second end of the second resistor and the first coil pin of the charging relay are both used for connecting a VCC pin.

8. The frequency inverter control circuit of claim 7, wherein, The first resistor is multiple, and the multiple first resistors are connected in series.

9. The frequency inverter control circuit of claim 1, wherein, The frequency converter control circuit further comprises an inverter unit (60), and the inverter unit (60) comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm which are respectively composed of two switching tubes; The rectifier unit (10) comprises a first bridge arm and a second bridge arm which are respectively composed of two rectifier diodes; The middle point of the first bridge arm and the middle point of the second bridge arm are both used for connecting an AC power grid, one end of the first bridge arm and one end of the second bridge arm are both connected with the input end of the soft start unit (50), and the other end of the first bridge arm and the other end of the second bridge arm are both connected with the negative pole of the bus capacitor; The middle point of the third bridge arm, the middle point of the fourth bridge arm and the middle point of the fifth bridge arm are respectively used for connecting a motor (70), and the two ends of the third bridge arm, the two ends of the fourth bridge arm and the two ends of the fifth bridge arm are respectively connected with the two ends of the bus capacitor.

10. A smart device, comprising: The intelligent device comprises the frequency converter control circuit according to any one of claims 1-9. The first coil pin of the charging relay is connected with the collector of the first power device and the first end of the second resistor respectively, the gate of the first power device is connected with the second output end of the master control unit (30), and the emitter of the first power device is connected with the output end of the protection unit (20) and the output end of the backup protection unit (40) respectively. The second end of the second resistor and the first coil pin of the charging relay are both used for connecting a VCC pin. The first resistor is multiple, and the multiple first resistors are connected in series. The frequency converter control circuit further comprises an inverter unit (60), and the inverter unit (60) comprises a third bridge arm, a fourth bridge arm and a fifth bridge arm which are respectively composed of two switching tubes; The rectifier unit (10) comprises a first bridge arm and a second bridge arm which are respectively composed of two rectifier diodes; The middle point of the first bridge arm and the middle point of the second bridge arm are both used for connecting an AC power grid, one end of the first bridge arm and one end of the second bridge arm are both connected with the input end of the soft start unit (50), and the other end of the first bridge arm and the other end of the second bridge arm are both connected with the negative pole of the bus capacitor; The middle point of the third bridge arm, the middle point of the fourth bridge arm and the middle point of the fifth bridge arm are respectively used for connecting a motor (70), and the two ends of the third bridge arm, the two ends of the fourth bridge arm and the two ends of the fifth bridge arm are respectively connected with the two ends of the bus capacitor. The intelligent device comprises the frequency converter control circuit according to any one of claims 1-9.

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