Driving module protection circuit of asynchronous high-speed deep-well pump variable-frequency driver

Abstract

The invention discloses a driving module protection circuit for a variable frequency driver of an asynchronous high-speed deep-well pump, and belongs to the technical field of asynchronous high-speed deep-well pumps. The invention aims to solve the technical problem of how to avoid a working fault of a driver under an over-current condition. The main points of the technical scheme are that the inverter comprises a rectification circuit, an inverter circuit and a master control circuit, the rectification circuit is provided with a cathode output end, the inverter circuit is provided with a cathode input end, the cathode output end is connected with a switch transistor, the output end of the switch transistor is connected with one end of a sampling resistor, and the other end of the sampling resistor is connected with the cathode input end of the inverter circuit. The control end of the switch transistor is connected with the output end of the current detection processing circuit, the two ends of the sampling resistor are further connected with the two input ends of the current detection processing circuit respectively, the output end of the current detection processing circuit is further connected with the main control circuit, and the circuit breaking protection effect is achieved when the current exceeding condition is detected.

Description

Technical Field

[0001] The invention relates to the technical field of asynchronous high-speed deep-well pumps, and in particular to a protection circuit for a variable-frequency drive module of an asynchronous high-speed deep-well pump. Background Art

[0002] Asynchronous high-speed deep well pump is a special water pump driven by asynchronous motor, designed with high speed, specially used for deep well pumping operation. Its core feature is that it combines the structural advantages of asynchronous motor, high speed operation capability, and the long-axis multi-stage impeller design of deep well pump, which is suitable for efficient water extraction from wells from tens to hundreds of meters deep. In practical applications, it is also necessary to combine with variable frequency drive, which can save energy and achieve stepless speed regulation. For example Figure 1 The topological circuit principle of one of the variable frequency drives shown in the figure. The variable frequency drive drive module includes a rectifier circuit, an inverter circuit, a main control circuit, and an asynchronous motor M. The rectifier circuit converts AC power into DC power, and the DC power is output to the asynchronous motor M through the inverter circuit. The inverter circuit is controlled by the main control circuit.

[0003] During the operation of the asynchronous high-speed deep well pump frequency converter, if the current exceeds the limit, the asynchronous high-speed deep well pump frequency converter will be damaged, the inverter circuit (module) will be scrapped, and in more serious cases, there will be a risk of fire. In addition, the shutdown measure of only cutting off the IGBT module in the inverter circuit (module) is not enough, and the frequency converter will also be damaged in the case of excessive current.

[0004] In order to solve the above-mentioned series of influences, the present invention provides an asynchronous high-speed deep well pump variable frequency drive drive module protection circuit, which can effectively solve the above-mentioned problems. Summary of the invention

[0005] In order to solve the above technical problems and shortcomings: how to effectively avoid protecting the variable frequency drive in the event of overcurrent, the present invention provides an asynchronous high-speed deep well pump variable frequency drive drive module protection circuit.

[0006] In order to achieve the above-mentioned purpose and other related purposes, the present invention adopts the following technical solutions:

[0007] An asynchronous high-speed deep well pump variable frequency drive drive module protection circuit includes a rectifier circuit, an inverter circuit, and a main control circuit. The output end of the rectifier circuit has a positive output end and a negative output end. The input end of the inverter circuit has a positive input end and a negative input end. The negative output end is connected to a switching transistor. The output end of the switching transistor is connected to one end of a sampling resistor. The other end of the sampling resistor is connected to the negative input end of the inverter circuit.

[0008] The control end of the switch transistor is connected to the output end of the current detection processing circuit.

[0009] The two ends of the sampling resistor are also connected to the two input ends of the current detection processing circuit respectively, and the output end of the current detection processing circuit is also connected to the main control circuit, wherein the sampling resistor collects current signals to the current detection processing circuit. When the collected current is normal, one pin of the current detection processing circuit controls the switching transistor to turn on, otherwise it controls the switching transistor to turn off, and outputs a feedback signal to the main control circuit at another pin.

[0010] Preferably, the switching transistor is an NMOS transistor or an NPN transistor.

[0011] Preferably, the current detection processing circuit includes a resistor R2, a capacitor C6, a signal converter, and a comparison module, the first end of the sampling resistor is connected to one end of the capacitor C6, the third pin of the signal converter, and the fourth pin of the signal converter, the second end of the sampling resistor is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the other end of the capacitor C6 and the second pin of the signal converter, the first pin of the signal converter is connected to the first voltage source VDD, the output pin of the signal converter is connected to the comparison module, the first output end of the comparison module is connected to the control end of the switching transistor, and the second output end of the comparison module is connected to the main control circuit.

[0012] Preferably, the comparison module includes a comparator, a resistor R4, a capacitor C5, a resistor R103, a resistor R104 and a resistor R114, the second voltage source VCC is connected to one end of the resistor R103, the other end of the resistor R103 is connected to one end of the resistor R104 and the non-inverting input end of the comparator, the other end of the resistor R104 is grounded, one end of the resistor R4 serves as an input end, the other end of the resistor R4 is connected to one end of the capacitor C5 and the inverting input end of the comparator, the other end of the capacitor C5 is grounded, the output end of the comparator is connected to one end of the resistor R114 and serves as a first output end, and the other end of the resistor R114 serves as a second output end.

[0013] Preferably, the signal converter includes a photoelectric isolation amplifier and / or an operational amplifier circuit.

[0014] Preferably, the photoelectric isolation amplifier is of model: HCPL-7840.

[0015] In summary, the invention has at least one of the following beneficial technical effects:

[0016] Under normal circumstances, when the power is input, it is converted into DC by the rectifier circuit to supply power to the inverter circuit, and also generates power for the control circuit. After the control circuit is powered, the normal current is sampled through the sampling resistor (RX1) in the busbar and passes through the current detection processing circuit, which can apply a positive voltage to the gate (G pole) (MX_PCTLO signal) of the IGBT transistor in the switching transistor to form a conductive channel, and the current flows from the collector to the emitter (that is, the negative output end flows to the negative input end), so that the drive circuit forms a loop.

[0017] When an overcurrent situation occurs, the gate (G pole) of the IGBT transistor in the switching transistor implements zero voltage, causing the conductive channel of the IGBT transistor to disappear, the current to stop, and no loop can be formed, thereby achieving the effect of protecting the water pump controller drive module. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the topology of the variable frequency drive circuit of the prior art;

[0019] Figure 2 It is a circuit diagram of an embodiment of the present invention.

[0020] Description of the reference numerals of the main components:

[0021] 100, rectifier circuit; 101, positive output terminal; 102, negative output terminal; 200, inverter circuit; 201, positive input terminal; 202, negative input terminal; 300, main control circuit; 400, switching transistor; 500, sampling resistor; 600, current detection processing circuit; 601, signal converter; 602, comparison module. DETAILED DESCRIPTION

[0022] The following is an explanation of the embodiments of the present invention by specific examples. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments. The details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0023] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention. The illustrations only show the components related to the present invention rather than being drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the type, quantity and proportion of each component can be changed at will, and the component layout type may also be more complicated.

[0024] The specific implementation manner of the present invention will be further described below in conjunction with the accompanying drawings.

[0025] Example:

[0026] The invention discloses an asynchronous high-speed deep well pump variable frequency drive module protection circuit, referring to Figure 2 As shown, the rectifier circuit 100, the inverter circuit 200, and the main control circuit 300 are included. The output end of the rectifier circuit 100 has a positive output end 101 (P+) and a negative output end 102, the input end of the inverter circuit 200 has a positive input end 201 (DC+) and a negative input end 202 (PGND1), the negative output end 102 is connected to a switch transistor 400, the output end of the switch transistor 400 is connected to one end of a sampling resistor 500 (RX1), and the other end of the sampling resistor 500 is connected to the negative input end 202 of the inverter circuit 200. The control end of the switch transistor 400 is connected to the output end of the current detection processing circuit 600. The two ends of the sampling resistor 500 are also respectively connected to the two input ends of the current detection processing circuit 600, and the output end of the current detection processing circuit 600 is also connected to the main control circuit 300. Among them, the sampling resistor 500 collects current signals to the current detection processing circuit 600. When the collected current is normal, one pin of the current detection processing circuit 600 controls the switch transistor 400 to turn on, otherwise it controls the switch transistor 400 to turn off, and outputs a feedback signal to the main control circuit 300 at another pin.

[0027] In a specific solution, the switch transistor 400 of this embodiment adopts an IGBT transistor. In addition, in other embodiments, it can also be an NMOS tube or an NPN transistor. IGBT (insulated gate bipolar transistor) combines the advantages of MOSFET (field effect transistor) and BJT (bipolar junction transistor). The gate (control terminal) and emitter of IGBT are isolated by an insulating layer to form a high input impedance. Only microampere current is required to control the on and off, the drive circuit design is simple, the power consumption is low, and it is suitable for high-frequency switching applications (such as inverters, switching power supplies). Comparison: Compared with BJT requiring milliampere base current, IGBT driving cost is lower. When IGBT is turned on, it exhibits bipolar conductive characteristics and high carrier concentration. The on-state voltage drop (Vce(sat)) is significantly lower than that of MOSFET, especially in high voltage and high current scenarios, the conduction loss is lower and the energy efficiency is higher. Suitable for industrial motor drive. The switching speed of IGBT is close to that of MOSFET, and it has the current handling capacity of bipolar devices. Supporting high-frequency switching (up to tens of kHz), it can reduce the size of passive components such as transformers and inductors and improve power density. In inverters, high-frequency PWM control can reduce harmonic interference and improve motor operating efficiency. The single tube withstand voltage range is from 600V to 6500V, and the current can reach thousands of amperes. IGBT heats up more evenly when turned on and has secondary breakdown protection capability.

[0028] Further, the current detection processing circuit 600 includes a resistor R2, a capacitor C6, a signal converter 601, and a comparison module 602. A first end of the sampling resistor 500 is connected to one end of the capacitor C6, a third pin of the signal converter 601, and a fourth pin of the signal converter 601, a second end of the sampling resistor 500 is connected to one end of the resistor R2, the other end of the resistor R2 is connected to the other end of the capacitor C6 and a second pin of the signal converter 601, a first pin of the signal converter 601 is connected to a first voltage source VDD, an output pin of the signal converter 601 is connected to the comparison module 602, a first output end of the comparison module 602 is connected to the control end of the switch transistor 400, and a second output end of the comparison module 602 is connected to the main control circuit 300.

[0029] The resistor R2 and the capacitor C6 form a filter, which effectively performs filtering processing for current sampling, thereby improving the reliability of current sampling. The first voltage source VDD can be 5V or 3V, etc.

[0030] The comparison module 602 includes a comparator, a resistor R4, a capacitor C5, a resistor R103, a resistor R104 and a resistor R114. The second voltage source VCC is connected to one end of the resistor R103, the other end of the resistor R103 is connected to one end of the resistor R104 and the non-inverting input end of the comparator, the other end of the resistor R104 is grounded, one end of the resistor R4 serves as an input end, the other end of the resistor R4 is connected to one end of the capacitor C5 and the inverting input end of the comparator, the other end of the capacitor C5 is grounded, the output end of the comparator is connected to one end of the resistor R114 and serves as a first output end, and the other end of the resistor R114 serves as a second output end.

[0031] Resistor R4 and capacitor C5 also form a filter circuit, which further filters the output of signal converter 601 and improves the stability of comparator operation. Resistor R103 and resistor R104 form a reference signal output of resistor voltage division, that is, a comparative reference value, and voltage source Vcc divides the voltage through resistor R103 and resistor R104 to form a comparative reference voltage value. If the sampled current is very large and exceeds the reference voltage value, then comparator U8 will output a low level, thereby achieving a low voltage output, and then switch transistor 400 will be turned off, thereby achieving overcurrent protection.

[0032] In addition, specifically, the signal converter 601 includes an optoelectronic isolation amplifier and / or an operational amplifier circuit. The optoelectronic isolation amplifier is model: HCPL-7840. The optoelectronic isolation amplifier achieves complete isolation between the input and output circuits through an optocoupler (optical transmitter + optical receiver), blocking the common-mode voltage and ground loop current. Prevent transient interference such as high voltage, surge or lightning from damaging subsequent equipment. The optical signal is not affected by the electromagnetic field, and the isolation layer blocks the high-frequency noise conduction path. Maintain signal integrity in strong electromagnetic interference environments such as motor drives and inverters. The built-in high-gain operational amplifier can amplify weak signals at the μV level to the usable range of subsequent circuits.

[0033] In summary, the overall working situation is as follows:

[0034] Under normal circumstances, when the power is input, it is converted into direct current by the rectifier circuit 100, and the inverter circuit 200 is powered, and the control circuit is also powered. After the control circuit is powered, the normal current is sampled through the sampling resistor 500 (RX1) in the busbar and passes through the current detection processing circuit 600, and a positive voltage can be applied to the gate (G pole) (MX_PCTLO signal) of the IGBT transistor in the switching transistor 400 to form a conductive channel, and the current flows from the collector to the emitter (that is, the negative output terminal 102 flows to the negative input terminal 202), so that the drive circuit forms a loop.

[0035] When an overcurrent situation occurs, the gate (G pole) of the IGBT transistor in the switch transistor 400 implements zero voltage, causing the conductive channel of the IGBT transistor to disappear, the current to stop, and no loop can be formed, thereby achieving the effect of protecting the water pump controller drive module.

[0036] The above embodiments are only illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the technology may modify or change the above embodiments without violating the spirit and scope of the present invention. Therefore, any equivalent changes made to the structure, shape, and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. An asynchronous high-speed deep well pump variable frequency drive drive module protection circuit, comprising a rectifier circuit (100), an inverter circuit (200), and a main control circuit (300), wherein the output end of the rectifier circuit (100) comprises a positive output end (101) and a negative output end (102), and the input end of the inverter circuit (200) comprises a positive input end (201) and a negative input end (202), wherein: The negative output terminal (102) is connected to a switch transistor (400), the output terminal of the switch transistor (400) is connected to one end of a sampling resistor (500), and the other end of the sampling resistor (500) is connected to the negative input terminal (202) of the inverter circuit (200). The control end of the switch transistor (400) is connected to the output end of the current detection processing circuit (600). The two ends of the sampling resistor (500) are also respectively connected to the two input ends of the current detection processing circuit (600), and the output end of the current detection processing circuit (600) is also connected to the main control circuit (300), wherein the sampling resistor (500) collects current signals and sends them to the current detection processing circuit (600). When the collected current is normal, one pin of the current detection processing circuit (600) controls the switch transistor (400) to turn on, otherwise, the switch transistor (400) is controlled to turn off, and a feedback signal is output to the main control circuit (300) at another pin.

2. The asynchronous high-speed deep well pump variable frequency drive drive module protection circuit according to claim 1, characterized in that: The switch transistor (400) is an IGBT transistor, an NMOS transistor, or an NPN transistor.

3. The asynchronous high-speed deep well pump variable frequency drive drive module protection circuit according to claim 1, characterized in that: The current detection processing circuit (600) comprises a resistor R2, a capacitor C6, a signal converter (601), and a comparison module (602); a first end of the sampling resistor (500) is connected to one end of the capacitor C6, a third pin of the signal converter (601), and a fourth pin of the signal converter (601); a second end of the sampling resistor (500) is connected to one end of the resistor R2; the other end of the resistor R2 is connected to the other end of the capacitor C6 and the second pin of the signal converter (601); a first pin of the signal converter (601) is connected to a first voltage source VDD; an output pin of the signal converter (601) is connected to the comparison module (602); a first output end of the comparison module (602) is connected to a control end of a switch transistor (400); and a second output end of the comparison module (602) is connected to a main control circuit (300).

4. The asynchronous high-speed deep well pump variable frequency drive drive module protection circuit according to claim 3, characterized in that: The comparison module (602) comprises a comparator, a resistor R4, a capacitor C5, a resistor R103, a resistor R104 and a resistor R114, a second voltage source VCC is connected to one end of the resistor R103, the other end of the resistor R103 is connected to one end of the resistor R104 and the non-inverting input end of the comparator, the other end of the resistor R104 is grounded, one end of the resistor R4 serves as an input end, the other end of the resistor R4 is connected to one end of the capacitor C5 and the inverting input end of the comparator, the other end of the capacitor C5 is grounded, the output end of the comparator is connected to one end of the resistor R114 and serves as a first output end, and the other end of the resistor R114 serves as a second output end.

5. The asynchronous high-speed deep well pump variable frequency drive drive module protection circuit according to claim 3, characterized in that: The signal converter (601) comprises a photoelectric isolation amplifier and / or an operational amplifier circuit.

6. The asynchronous high-speed deep well pump variable frequency drive drive module protection circuit according to claim 5, characterized in that: The photoelectric isolation amplifier is model: HCPL-7840.

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