Coil driving circuit, control system of release and circuit breaker

Abstract

The invention provides a coil driving circuit, a control system of a release and a circuit breaker. The coil driving circuit comprises a first operational amplifier, a first switching device, a first feedback regulation module and a second feedback regulation module. A first operational amplifier serves as a core, a first feedback regulation module and a second feedback regulation module respectively regulate first voltage output to a first input end of the first operational amplifier and second voltage output to a second input end of the first operational amplifier according to output of the first operational amplifier, and finally the first operational amplifier outputs PWM voltage to a first switching device. Therefore, the driving of the release is realized in a PWM driving mode. Firstly, the electrifying condition of the release can be influenced, the release is prevented from working for a long time, the heat productivity is reduced, the release is not easy to burn down, and the potential safety hazard is reduced; and secondly, the tripper with few turns and small equivalent resistance can be used for working, so that the cost of the tripper is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of circuit breakers, and in particular to a coil drive circuit, a release control system and a circuit breaker. Background Art

[0002] The circuit breaker uses the release as the core to realize various electrical protection functions. At present, most of the releases on the market use high-voltage direct drive mode, that is, the input voltage is directly connected to the release after rectification. However, the input voltage of the existing undervoltage release is mostly AC230V or AC380V, which is a relatively high voltage. When using the direct drive mode, the release has strict requirements, that is, more turns and larger equivalent resistance. Only in this case can it work normally under long-term high voltage direct drive.

[0003] However, the existing solutions have many disadvantages. The first is the problem of heat generation. Since the releaser needs to work for a long time, heat generation is inevitable. Such long-term high-voltage working mode generates a lot of heat. If there is no good heat dissipation method, the releaser is easy to burn out, which poses certain safety hazards. The second is the cost issue. The large number of turns of the releaser will relatively increase the consumables of the coil in the releaser, resulting in increased costs. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a coil drive circuit, a control system of a release and a circuit breaker.

[0005] In a first aspect, in one embodiment, the present invention provides a coil driving circuit, the coil driving circuit comprising a first operational amplifier, a first switching device, a first feedback regulation module and a second feedback regulation module;

[0006] The first feedback regulation module includes a power supply terminal for connecting to a first working voltage, a feedback terminal electrically connected to an output terminal of the first operational amplifier and a controlled terminal of the first switching device respectively, and an output terminal electrically connected to a first input terminal of the first operational amplifier;

[0007] The first access terminal and the second access terminal of the first switch device are connected in series with the release coil, and are used to control the current of the release coil;

[0008] The second feedback regulation module includes a feedback end electrically connected to the output end of the first operational amplifier and an output end electrically connected to the second input end of the first operational amplifier;

[0009] The first operational amplifier is used for outputting a PWM voltage to the first switching device through its output terminal according to a first voltage at its first input terminal and a second voltage at its second input terminal.

[0010] In one embodiment, the first feedback regulation module includes a first voltage-dividing resistor, a second voltage-dividing resistor, and a third voltage-dividing resistor;

[0011] The first end of the first voltage-dividing resistor is used to connect to the first working voltage, the second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor, the first end of the third voltage-dividing resistor and the in-phase input terminal of the first operational amplifier, the second end of the second voltage-dividing resistor is used to be grounded, and the second end of the third voltage-dividing resistor is electrically connected to the output terminal of the first operational amplifier and the controlled end of the first switching device.

[0012] In one embodiment, the first feedback regulation module includes a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, and a second switch device;

[0013] The first end of the first voltage-dividing resistor and the first end of the third voltage-dividing resistor are respectively used to access the first working voltage, the second end of the first voltage-dividing resistor is respectively electrically connected to the first end of the second voltage-dividing resistor, the first access end of the second switching device and the in-phase input end of the first operational amplifier, the second end of the second voltage-dividing resistor is used to be grounded, the second end of the third voltage-dividing resistor is electrically connected to the second access end of the second switching device, and the controlled end of the second switching device is respectively electrically connected to the output end of the first operational amplifier and the controlled end of the first switching device.

[0014] In one embodiment, the second feedback regulation module includes a capacitor, a first charge-discharge resistor, and a second charge-discharge resistor;

[0015] The first end of the capacitor is electrically connected to the inverting input end of the first operational amplifier and the first end of the first charge-discharge resistor, respectively; the second end of the first charge-discharge resistor is electrically connected to the output end of the first operational amplifier, the controlled end of the first switching device, and the first end of the second charge-discharge resistor, respectively; the second end of the capacitor and the second end of the second charge-discharge resistor are used for grounding, respectively.

[0016] In one embodiment, the second feedback regulation module further includes an isolation diode;

[0017] The cathode of the isolation diode is electrically connected to the second end of the first charge-discharge resistor and the first end of the second charge-discharge resistor respectively, and the anode of the isolation diode is electrically connected to the output end of the first operational amplifier and the controlled end of the first switch device respectively.

[0018] In one embodiment, the second feedback regulation module includes a capacitor, a first charge-discharge resistor, and a second charge-discharge resistor;

[0019] The first end of the capacitor is electrically connected to the inverting input end of the first operational amplifier and the first end of the first charge-discharge resistor, respectively; the second end of the first charge-discharge resistor is electrically connected to the first access end of the first switching device and the first end of the second charge-discharge resistor, respectively; the second end of the capacitor and the second end of the second charge-discharge resistor are used for grounding, respectively.

[0020] In one embodiment, the second feedback regulation module further includes a clamping diode;

[0021] The anode of the clamping diode is electrically connected to the second end of the first charge-discharge resistor, the first end of the second charge-discharge resistor and the first access end of the first switch device respectively, and the cathode of the clamping diode is used for grounding.

[0022] In a second aspect, in one embodiment, the present invention provides a control system for a release, wherein the controller of the release comprises an undervoltage control circuit and a coil drive circuit in any one of the above embodiments;

[0023] The power supply end of the undervoltage control circuit is used to access the second working voltage, the input end of the undervoltage control circuit is used to access the sampling voltage of the power supply, and the output end of the undervoltage control circuit is electrically connected to the power supply end of the first feedback regulation module;

[0024] The undervoltage control circuit is used to output a first operating voltage to the first feedback regulation module when the sampled voltage is greater than a preset voltage.

[0025] In one embodiment, the undervoltage control circuit includes a first voltage stabilizing diode, a second operational amplifier, a fourth voltage dividing resistor and a PNP transistor;

[0026] The cathode of the first voltage-regulating diode is respectively electrically connected to the in-phase input terminal of the second operational amplifier and the first end of the fourth voltage-dividing resistor and is used to access the second working voltage. The anode of the first voltage-regulating diode is used to be grounded. The inverting input terminal of the second operational amplifier is used to access the sampling voltage. The second end of the fourth voltage-dividing resistor is respectively electrically connected to the output terminal of the second operational amplifier and the base of the PNP transistor. The emitter of the PNP transistor is used to access the second working voltage. The collector of the PNP transistor is electrically connected to the power supply terminal of the first feedback regulation module.

[0027] In one embodiment, the control system of the trip unit further includes a power supply circuit and a sampling circuit;

[0028] The input end of the power supply circuit and the input end of the sampling circuit are respectively used to access the power supply voltage, the output end of the power supply circuit is electrically connected to the power supply end of the undervoltage control circuit, and the output end of the sampling circuit is electrically connected to the input end of the undervoltage control circuit.

[0029] In one embodiment, the power supply circuit includes an NPN transistor and a second voltage regulator diode;

[0030] The collector of the NPN transistor, the base of the NPN transistor and the cathode of the second zener diode are respectively used to access the power supply voltage, the emitter of the NPN transistor is electrically connected to the power supply end of the undervoltage control circuit, and the anode of the second zener diode is used for grounding.

[0031] In one embodiment, the sampling circuit includes a fifth voltage-dividing resistor and a sixth voltage-dividing resistor;

[0032] The first end of the fifth voltage-dividing resistor is used to access the power supply voltage, the second end of the fifth voltage-dividing resistor is electrically connected to the first end of the sixth voltage-dividing resistor and the input end of the undervoltage control circuit respectively, and the second end of the sixth voltage-dividing resistor is used to be grounded.

[0033] In a third aspect, in one embodiment, the present invention provides a circuit breaker, including a trip unit and a control system of the trip unit in any one of the above embodiments.

[0034] Through the above-mentioned coil driving circuit, the control system of the release and the circuit breaker, a first operational amplifier, a first feedback adjustment module and a second feedback adjustment module are set. With the first operational amplifier as the core, the first feedback adjustment module and the second feedback adjustment module respectively adjust the first voltage output to the first input terminal and the second voltage output to the second input terminal of the first operational amplifier according to the output of the first operational amplifier, so that the first operational amplifier finally outputs a PWM voltage to the first switching device, thereby realizing the driving of the release by PWM driving; firstly, it can affect the power-on condition of the release, avoid the release from working for a long time, reduce the heat generation, and is not easy to burn the release, thereby reducing the safety hazard; secondly, a release with a small number of turns and a small equivalent resistance can be used for work, thereby reducing the cost of the release. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic diagram of the structure of a coil driving circuit in one embodiment of the present invention;

[0037] Figure 2 A schematic diagram of a specific circuit implementation of a coil driving circuit in one embodiment of the present invention;

[0038] Figure 3 A schematic diagram of a specific circuit implementation of a first feedback regulation module in another embodiment of the present invention;

[0039] Figure 4 A schematic diagram of a specific circuit implementation of a second feedback regulation module in another embodiment of the present invention;

[0040] Figure 5 It is a schematic diagram of the structure of a control system of a release in one embodiment of the present invention;

[0041] Figure 6 A schematic diagram of a specific circuit implementation of an undervoltage control circuit in one embodiment of the present invention;

[0042] Figure 7 It is a structural schematic diagram of a control system of a trip device including a power supply circuit and a sampling circuit in one embodiment of the present invention;

[0043] Figure 8 A schematic diagram of a specific circuit implementation of a power supply circuit in one embodiment of the present invention;

[0044] Fig. 9 A schematic diagram of a specific circuit implementation of a sampling circuit in one embodiment of the present invention;

[0045] Fig.10 It is a structural schematic diagram of a control system of a trip device including a rectifier and filter circuit in one embodiment of the present invention;

[0046] Fig.11 The figure is a schematic diagram of a specific circuit implementation of a rectifier and filter circuit in one embodiment of the present invention. DETAILED DESCRIPTION

[0047] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present invention.

[0048] In the description of the present invention, it should be understood that the terms "first" and "second" are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In the present application, the word "exemplary" is used to mean "used as an example, illustration or description". Any embodiment described as "exemplary" in the present application is not necessarily interpreted as being more preferred or more advantageous than other embodiments. In order to enable any person skilled in the art to implement and use the present invention, the following description is given. In the following description, details are listed for the purpose of explanation. It should be understood that a person of ordinary skill in the art can recognize that the present invention can be implemented without using these specific details. In other examples, well-known structures and processes will not be elaborated in detail to avoid unnecessary details that make the description of the present invention obscure. Therefore, the present invention is not intended to be limited to the embodiments shown, but is consistent with the widest range of principles and features disclosed in the present application.

[0049] First, as Figure 1As shown, in one embodiment, the present invention provides a coil driving circuit, the coil driving circuit includes a first operational amplifier U501, a first switching device (such as Figure 1 MOS tube Q501 in the circuit), a first feedback regulation module and a second feedback regulation module.

[0050] In other embodiments, other switches besides MOS tubes may be used as the first switch device, such as triodes, IGBT tubes, etc.

[0051] exist Figure 1 In the embodiment, the power supply end of the first feedback regulation module is used to access the first working voltage VCC_2, the feedback end of the first feedback regulation module is electrically connected to the output end of the first operational amplifier U501 and the gate of the MOS tube Q501 respectively to access the target voltage UoB output by the first operational amplifier U501, and the output end of the first feedback regulation module is electrically connected to the first input end of the first operational amplifier U501 to output the first voltage UpB to the first operational amplifier U501.

[0052] The first feedback regulation module can regulate the first voltage UpB output to the first operational amplifier U501 according to the target voltage UoB output by the first operational amplifier U501.

[0053] exist Figure 1 In the embodiment, the drain and source of the MOS tube Q501 are connected in series with the release coil connected to the terminal P2, so as to control the current of the release coil.

[0054] The first end of the terminal P2 is used to connect the power supply voltage DC+ of the power supply, the second end of the terminal P2 is used to be electrically connected to the drain of the MOS tube Q501, and the source of the MOS tube Q501 is used to be grounded. When the MOS tube Q501 is in the on state, the connected power supply voltage DC+ can pass through the trip coil connected to the terminal P2 and the MOS tube Q501 to the ground, forming a current loop, and the trip coil is powered on and works normally; similarly, when the MOS tube Q501 is in the off state, the connected power supply voltage DC+ cannot pass through the trip coil connected to the terminal P2 and the MOS tube Q501 to the ground, and cannot form a current loop, and the trip coil is powered off and stops working.

[0055] exist Figure 1 In the embodiment, the feedback end of the second feedback regulation module is electrically connected to the output end of the first operational amplifier U501 to access the target voltage UoB output by the first operational amplifier U501, and the output end of the second feedback regulation module is electrically connected to the second input end of the first operational amplifier U501 to output the second voltage UnB to the first operational amplifier U501.

[0056] The second feedback regulation module can regulate the second voltage UnB output to the first operational amplifier U501 according to the target voltage UoB output by the first operational amplifier U501.

[0057] The first operational amplifier U501 is used to output a PWM voltage, such as a target voltage UoB, to the MOS tube Q501 through its output terminal according to a first voltage UpB at its first input terminal and a second voltage UnB at its second input terminal.

[0058] Among them, the target voltage UoB output by the first operational amplifier U501 can respectively make the first feedback regulation module and the second feedback regulation module perform corresponding voltage regulation, so that the magnitude relationship between the first voltage UpB and the second voltage UnB output after regulation changes, thereby changing the target voltage UoB output by the first operational amplifier U501, thereby realizing a cycle, so that the target voltage UoB output by the first operational amplifier U501 is in the form of a PWM wave.

[0059] Specifically, when the target voltage UoB is at a high level, the magnitude relationship between the first voltage UpB and the second voltage UnB is converted from the first voltage UpB being greater than the second voltage UnB to the second voltage UnB being greater than the first voltage UpB, thereby converting the target voltage UoB to a low level; when the target voltage UoB is at a low level, the magnitude relationship between the first voltage UpB and the second voltage UnB is converted from the second voltage UnB being greater than the first voltage UpB to the first voltage UpB being greater than the second voltage UnB, thereby converting the target voltage UoB to a high level; this cycle is repeated, and ultimately the output target voltage UoB is a PWM wave.

[0060] Among them, when the target voltage UoB used to drive the MOS tube Q501 is a PWM wave, it can be turned on and off according to the corresponding duty cycle, so as to control the current on the release coil in a PWM manner.

[0061] Through the coil driving circuit, a first operational amplifier, a first feedback adjustment module and a second feedback adjustment module are provided. With the first operational amplifier as the core, the first feedback adjustment module and the second feedback adjustment module respectively adjust the first voltage output to the first input terminal and the second voltage output to the second input terminal of the first operational amplifier according to the output of the first operational amplifier, so that the first operational amplifier finally outputs a PWM voltage to the first switching device, thereby realizing the driving of the release by PWM driving. Firstly, it can affect the power-on condition of the release, avoid the release from working for a long time, reduce the heat generation, and is not easy to burn the release, thereby reducing the safety hazard. Secondly, a release with a small number of turns and a small equivalent resistance can be used for work, thereby reducing the cost of the release.

[0062] like Figure 2As shown, in one embodiment, the first feedback regulation module includes a first voltage-dividing resistor R501, a second voltage-dividing resistor R502 and a third voltage-dividing resistor R503; the second feedback regulation module includes a capacitor C502, a first charge-discharge resistor R504 and a second charge-discharge resistor R505.

[0063] Among them, the first end of the first voltage-dividing resistor R501 is used to access the first working voltage VCC_2, the second end of the first voltage-dividing resistor R501 is electrically connected to the first end of the second voltage-dividing resistor R502, the first end of the third voltage-dividing resistor R503 and the in-phase input end of the first operational amplifier U501, the second end of the second voltage-dividing resistor R502 is used for grounding, and the second end of the third voltage-dividing resistor R503 is electrically connected to the output end of the first operational amplifier U501 and the gate of the MOS tube Q501. Among them, the first end of the capacitor C502 is electrically connected to the inverting input end of the first operational amplifier U501 and the first end of the first charge-discharge resistor R504, the second end of the first charge-discharge resistor R504 is electrically connected to the output end of the first operational amplifier U501, the gate of the MOS tube Q501 and the first end of the second charge-discharge resistor R505, and the second end of the capacitor C502 and the second end of the second charge-discharge resistor R505 are used for grounding.

[0064] It should be noted that the “first input terminal of the first operational amplifier U501” and “the second input terminal of the first operational amplifier U501” mentioned in the above embodiment are general expressions, while the “non-inverting input terminal of the first operational amplifier U501” and “the inverting input terminal of the first operational amplifier U501” in this embodiment are specific expressions under specific limited scenarios.

[0065] Before the circuit is powered on, the target voltage UoB is at a low level (e.g. Figure 2 The first voltage UpB is higher than the second voltage UnB, so the target voltage UoB output by the first operational amplifier U501 is converted to a high level (such as Figure 2 The first working voltage VCC_2 in the circuit is used as the first operating voltage VCC_2), and the capacitor C502 is charged through the isolation diode D502 and the first charge-discharge resistor R504, that is, the second voltage UnB starts to increase slowly. When the second voltage UnB is greater than the first voltage UpB, the target voltage UoB output by the first operational amplifier U501 is converted to a low level, and the first voltage UpB suddenly decreases. The capacitor C502 is discharged through the first charge-discharge resistor R504 and the second charge-discharge resistor R505, that is, the second voltage UnB starts to decrease gradually. When the second voltage UnB is less than the first voltage UpB, the target voltage UoB output by the first operational amplifier U501 is converted to a high level, and the first voltage UpB suddenly increases. The capacitor C502 starts to charge, and the whole circuit starts a new round of cycle, and so on and so forth to complete the generation of the PWM wave.

[0066] If the isolation diode D502 is not provided, a part of the current will flow to the first operational amplifier U501 during the discharge process of the capacitor C502, causing the output voltage of the first operational amplifier U501 to not suddenly change from a high level to a low level, but to gradually decrease from a high level to a low level, thereby affecting the voltage of the non-inverting input terminal of the first operational amplifier U501, and the output result cannot achieve the expected effect. After the isolation diode D502 is provided, when the capacitor C502 is discharged, the current can be prevented from flowing into the first operational amplifier U501, and the normal charging process of the capacitor C502 is not affected, thereby ensuring the integrity of the output signal.

[0067] Among them, the first voltage UpB depends on the connected first working voltage VCC_2, the target voltage UoB, the first voltage-dividing resistor R501, the second voltage-dividing resistor R502 and the third voltage-dividing resistor R503. Since only the target voltage UoB is a variable, the first voltage UpB will also change when the target voltage UoB changes. The relationship between the first voltage UpB and the target voltage UoB can be expressed as follows:

[0068]

[0069] The target voltage UoB can control the capacitor C502 to be in a charging state or a discharging state, thereby controlling the second voltage UnB to change.

[0070] From the above process analysis, it can be seen that to achieve the target voltage UoB as a PWM wave, the following two points need to be controlled:

[0071] (1) A change in the target voltage UoB output by the first operational amplifier U501 can cause a change in the first voltage UpB, and the first voltage UpB when the target voltage UoB is the first operating voltage VCC_2 needs to be greater than the first voltage UpB when the target voltage UoB is GND.

[0072] (2) A change in the target voltage UoB output by the first operational amplifier U501 can cause a change in the second voltage UnB. Specifically, a change in the target voltage UoB output by the first operational amplifier U501 can cause a change in the charge and discharge state of the capacitor C502. When the target voltage UoB is the first operating voltage VCC_2, the capacitor C502 is in a charging state. When the target voltage UoB is GND, the capacitor C502 is in a discharging state.

[0073] Regarding the first point above, in addition to the specific circuit structure of the first feedback adjustment module mentioned in the above embodiment, other specific circuit structures may also be used. Figure 3 As shown, in one embodiment, the first feedback regulation module includes a first voltage-dividing resistor R501, a second voltage-dividing resistor R502, a third voltage-dividing resistor R503 and a second switch device (such as Figure 3MOS tube Q502 in it).

[0074] Among them, the first end of the first voltage-dividing resistor R501 and the first end of the third voltage-dividing resistor R503 are respectively used to connect to the first working voltage VCC_2, the second end of the first voltage-dividing resistor R501 is respectively electrically connected to the first end of the second voltage-dividing resistor R502, the source of the MOS tube Q502 and the in-phase input terminal of the first operational amplifier U501, the second end of the second voltage-dividing resistor R502 is used to be grounded, the second end of the third voltage-dividing resistor R503 is electrically connected to the drain of the MOS tube Q502, and the gate of the MOS tube Q502 is respectively electrically connected to the output terminal of the first operational amplifier U501 and the gate of the MOS tube Q501.

[0075] Among them, before the circuit is powered on, the target voltage UoB output by the first operational amplifier U501 is GND, the MOS tube Q502 is in the off state, and the first voltage UpB is at a low level. At the moment of powering on the circuit, the first voltage UpB suddenly increases, the first voltage UpB is greater than the second voltage UnB, the target voltage UoB output by the first operational amplifier U501 suddenly changes to the first working voltage VCC_2, the MOS tube Q502 is in the on state, the capacitor C502 is charged, and the second voltage UnB gradually increases. Due to the conduction of the MOS tube Q502, the first voltage UpB increases a part. When the second voltage UnB is greater than the first voltage UpB, the target voltage UoB output by the first operational amplifier U501 suddenly changes to GND, the MOS tube Q502 is in the cut-off state, the capacitor C502 is discharged, the second voltage UnB gradually decreases, and the first voltage UpB is partially reduced. When the second voltage UnB is less than the first voltage UpB, the target voltage UoB output by the first operational amplifier U501 suddenly changes to the first operating voltage VCC_2, the capacitor C502 is charged, and the entire circuit starts a new round of cycle, and so on.

[0076] The relationship between the first voltage UpB and the target voltage UoB can be expressed as follows:

[0077]

[0078] Regarding the second point above, in addition to the specific circuit structure of the second feedback adjustment module mentioned in the above embodiment, other specific circuit structures may also be used. Figure 4 As shown, in one embodiment, the second feedback regulation module includes a capacitor C502, a first charge-discharge resistor R504 and a second charge-discharge resistor R505.

[0079] Among them, the first end of the capacitor C502 is electrically connected to the inverting input end of the first operational amplifier U501 and the first end of the first charge and discharge resistor R504 respectively, the second end of the first charge and discharge resistor R504 is electrically connected to the source of the MOS tube Q501 and the first end of the second charge and discharge resistor R505 respectively, and the second end of the capacitor C502 and the second end of the second charge and discharge resistor R505 are used for grounding respectively.

[0080] Before the circuit is powered on, the target voltage UoB is GND, so the second voltage UnB is at a low level. When the circuit starts to be powered on, the first voltage UpB increases, and the first voltage UpB is greater than the second voltage UnB. Therefore, the target voltage UoB output by the first operational amplifier U501 suddenly changes to the first operating voltage VCC_2, and the MOS tube Q501 is in a conducting state. The capacitor C502 is charged through the connected power supply voltage DC+, the trip coil connected to the terminal P2, the MOS tube Q501 and the first charge-discharge resistor R504. The second voltage UnB starts to increase slowly. When the second voltage When the target voltage UnB is greater than the first voltage UpB, the target voltage UoB output by the first operational amplifier U501 is converted to GND, the first voltage UpB suddenly decreases, and the capacitor C502 is discharged through the first charge-discharge resistor R504 and the second charge-discharge resistor R505, and the second voltage UnB begins to gradually decrease. When the second voltage UnB is less than the first voltage UpB, the target voltage UoB output by the first operational amplifier U501 is converted to a high level, the first voltage UpB suddenly increases, the capacitor C502 starts to charge, and the whole circuit starts a new round of cycle, and so on, to complete the generation of the PWM wave.

[0081] Among them, in this embodiment, the capacitor C502 is charged based on the power supply voltage DC+, and a release coil is required to form a loop. Therefore, when the release coil is not connected or disconnected due to a fault, the capacitor 502 cannot be charged, so that the second voltage UnB is always at a low level, and the first operational amplifier U501 cannot output the target voltage UoB in the form of a PWM wave.

[0082] like Figure 4 As shown, in one embodiment, the second feedback regulation module further includes a clamping diode D503.

[0083] The anode of the clamping diode D503 is electrically connected to the second end of the first charge-discharge resistor R504, the first end of the second charge-discharge resistor R505 and the source of the MOS tube Q501, respectively, and the cathode of the clamping diode D503 is grounded.

[0084] Among them, due to Figure 4The second charge-discharge resistor R505 is charged by the connected power supply voltage DC+ and the release coil. The current in this loop is large, which can easily damage the second charge-discharge resistor R505. The additional clamping diode D503 can clamp the voltage across the second charge-discharge resistor R505 to a smaller value to protect the second charge-discharge resistor R505.

[0085] It should be noted that the charging time of capacitor C502 is the high level duration of the PWM signal output, and the discharging time of capacitor C502 is the low level duration of the PWM signal output. Figure 4 Taking the specific circuit structure shown as an example, the value of the time constant τ of the capacitor C502 during the charging and discharging process is different, as shown below:

[0086] τ′=R504*C502 Charging process

[0087] τ″=(R504+R505)*C502 Discharge process

[0088] Under normal circumstances, the charging and discharging formula of capacitor C502 is:

[0089]

[0090] Among them, Vt is the voltage value at any time during the charging / discharging process, Vo is the initial voltage during the charging / discharging process, Vu is the power supply voltage value for charging the capacitor C502 during the charging process, and is represented by Uf in the schematic diagram, which is the forward conduction voltage drop of the clamping diode D503. Figure 4 It can be seen that when the voltage of capacitor C502 is charged to be greater than Up′B, the output of the first operational amplifier U501 is reversed, and capacitor C502 starts to discharge. When the voltage of capacitor C502 is discharged to be less than Up″B, the output of the first operational amplifier U501 is reversed, and capacitor C502 starts to charge. Therefore, the target values ​​of capacitor C502 during the charging and discharging process are Up′B and Up″B respectively. The time taken for charging and discharging capacitor C502 can be calculated by the formula, as shown below:

[0091]

[0092] When the first operational amplifier U501 works normally, the frequency and duty cycle of the output PWM wave can be expressed by the following formulas:

[0093]

[0094] Among them, it can be known from the formula of the charging and discharging time constant τ of the capacitor C502 that when the resistance value of the resistor R504 is much greater than the resistance value of the resistor R505, the time constant τ of the charging and discharging process of the capacitor C502 is approximately equal, that is, τ′≈τ″. Therefore, the formula of frequency and duty cycle can be adjusted as follows:

[0095] Frequency, where Duty cycle, where

[0096] It can be seen from the formula that, in theory, the duty cycle has no correlation with the time constant τ. Therefore, when adjusting the frequency and duty cycle of the PWM wave, the duty cycle can be determined first. To determine the duty cycle, it is only necessary to adjust the parameters of the four devices, namely, the clamping diode D503, the first voltage-dividing resistor R501, the second voltage-dividing resistor R502, and the third voltage-dividing resistor R503. After the duty cycle is determined, the time constant τ is adjusted, that is, the parameters of the first charge-discharge resistor R504 and the capacitor C502 are adjusted to determine the frequency.

[0097] Second, as Figure 5 As shown, in one embodiment, the present invention provides a control system for a release, and the controller of the release includes an undervoltage control circuit and the coil drive circuit in any one of the above embodiments.

[0098] Among them, the power supply end of the undervoltage control circuit is used to access the second working voltage VCC, the input end of the undervoltage control circuit is used to access the sampling voltage UnA of the power supply, and the output end of the undervoltage control circuit is electrically connected to the power supply end of the first feedback regulation module to output the first working voltage VCC_2.

[0099] The undervoltage control circuit is used for outputting the first working voltage VCC_2 to the first feedback regulation module when the sampling voltage UnA is greater than the preset voltage.

[0100] Among them, undervoltage protection is an important protection means of the circuit breaker. When the power supply is undervoltage, the power supply of the release coil needs to be cut off, thereby disconnecting the power supply of the subsequent power load. In this embodiment, when the sampled voltage is greater than the preset voltage, it can be determined that the power supply is not undervoltage, so that the first working voltage VCC_2 can be output to the first feedback regulation module in the coil drive circuit; conversely, when the sampled voltage is less than the preset voltage, it can be determined that the power supply is undervoltage, so that the first working voltage VCC_2 cannot be output to the first feedback regulation module in the coil drive circuit.

[0101] Through the control system of the above-mentioned release, a first operational amplifier, a first feedback adjustment module and a second feedback adjustment module are set. With the first operational amplifier as the core, the first feedback adjustment module and the second feedback adjustment module respectively adjust the first voltage output to the first input terminal and the second voltage output to the second input terminal of the first operational amplifier according to the output of the first operational amplifier, so that the first operational amplifier finally outputs a PWM voltage to the first switching device, thereby realizing the driving of the release by PWM driving; firstly, it can affect the power-on condition of the release, avoid the release from working for a long time, reduce the heat generation, and is not easy to burn the release, thereby reducing the safety hazard; secondly, a release with a small number of turns and a small equivalent resistance can be used for work, thereby reducing the cost of the release.

[0102] like Figure 6 As shown, in one embodiment, the undervoltage control circuit includes a first voltage stabilizing diode ZD401, a second operational amplifier U401, a fourth voltage dividing resistor R403 and a PNP transistor Q401.

[0103] Among them, the cathode of the first voltage-regulating diode is electrically connected to the in-phase input terminal of the second operational amplifier and the first end of the fourth voltage-dividing resistor through the resistor R402, and is used to access the second working voltage VCC through the resistor R401, the anode of the first voltage-regulating diode ZD401 is used for grounding, the inverting input terminal of the second operational amplifier U401 is used to access the sampling voltage UnA, the second end of the fourth voltage-dividing resistor R403 is electrically connected to the output terminal of the second operational amplifier U401 and the base of the PNP transistor Q401, the emitter of the PNP transistor Q401 is used to access the second working voltage VCC, and the collector of the PNP transistor Q401 is electrically connected to the power supply terminal of the first feedback regulation module to output the first working voltage VCC_2.

[0104] Among them, when the sampling voltage UnA gradually increases to be greater than the reference voltage UpA connected to the non-inverting input terminal of the second operational amplifier U401, the output state of the second operational amplifier U401 is reversed, that is, the output voltage UoA output by the second operational amplifier U401 suddenly changes from the second operating voltage VCC to GND, resulting in a decrease in the reference voltage UpA. Only when the sampling voltage UnA is lower than the reference voltage UpA at this time, the output of the second operational amplifier U401 will be reversed again. After the reversal again, the reference voltage UpA will increase with the sudden change of the output voltage UoA. Only when the sampling voltage UnA is higher than the reference voltage UpA at this time, the second operational amplifier U401 will be reversed again. The output end of the second operational amplifier U401 is connected to a PNP transistor Q401. When the output voltage UoA output by the second operational amplifier U401 is the second working voltage VCC, the PNP transistor Q401 is in the cut-off state, and the first working voltage VCC_2 loses power. When the output voltage UoA output by the second operational amplifier U401 is GND, the PNP transistor Q401 is in the on state, and the first working voltage VCC_2 is powered. The first working voltage VCC_2 is the power supply of the subsequent coil drive circuit. If it loses power, the subsequent coil drive circuit cannot work. Therefore, only when the sampling voltage UnA is greater than the reference voltage UpA, that is, when the input voltage of the power supply is within a certain range of the rated voltage, can the coil drive circuit work, thereby driving the release to operate.

[0105] The power supply of the undervoltage control circuit is completed by the second working voltage VCC. In the entire undervoltage control circuit, the cathode voltage Ut of the first voltage zener diode ZD401 is constant, which is the reverse breakdown voltage of the first voltage zener diode ZD401. The reference voltage UpA changes with the output voltage UoA output by the second operational amplifier U401. The specific relationship is as follows:

[0106]

[0107] From the equation, we can see that Up ′ A>Up″A, that is, when the second operational amplifier U401 outputs the second operating voltage VCC, the reference voltage UpA is higher. By selecting the appropriate resistance values ​​of the fourth voltage-dividing resistor R403 and the resistor R402, Up is satisfied. ′ A is smaller than the sampling voltage UnA under the rated voltage, and Up″A is larger than the sampling voltage UnA under 0.5 times the rated voltage, wherein Up″A can be adjusted according to actual conditions.

[0108] like Figure 7 As shown, in one embodiment, the control system of the trip unit further includes a power supply circuit and a sampling circuit.

[0109] Among them, the input end of the power supply circuit and the input end of the sampling circuit are respectively used to connect to the power supply voltage DC+, the output end of the power supply circuit is electrically connected to the power supply end of the undervoltage control circuit to output the second working voltage VCC, and the output end of the sampling circuit is electrically connected to the input end of the undervoltage control circuit to output the sampling voltage UnA.

[0110] like Figure 8 As shown, in one embodiment, the power supply circuit includes an NPN transistor Q202 and a second Zener diode ZD202.

[0111] Among them, the collector of the NPN transistor Q202, the base of the NPN transistor Q202 and the cathode of the second Zener diode ZD202 are respectively used to connect to the power supply voltage DC+, the emitter of the NPN transistor Q202 is electrically connected to the power supply end of the undervoltage control circuit to output the second working voltage VCC, and the anode of the second Zener diode ZD202 is used for grounding.

[0112] The power supply voltage DC+ of about 300V can generate a second working voltage VCC of about 12V after passing through a series voltage stabilizing circuit composed of an NPN transistor Q202 and a second voltage stabilizing diode ZD202.

[0113] like Fig. 9 As shown, in one embodiment, the sampling circuit includes a fifth voltage dividing resistor (such as Fig. 9 The resistors R301 and R302 in the circuit) and the sixth voltage-dividing resistor R303.

[0114] Among them, the first end of the resistor R301 is used to connect to the power supply voltage DC+, the second end of the resistor R301 is electrically connected to the first end of the resistor R302, the second end of the resistor R302 is electrically connected to the first end of the sixth voltage-dividing resistor R303 and the input end of the undervoltage control circuit respectively to output the sampling voltage UnA, and the second end of the sixth voltage-dividing resistor R303 is used for grounding.

[0115] Among them, the sampling circuit samples the power supply voltage DC+. After passing through three voltage-dividing resistors, namely resistor R301, resistor R302 and the sixth voltage-dividing resistor R303, when the power supply voltage DC+ is the rated voltage, the sampling voltage UnA is approximately 10V. When the power supply voltage DC+ slowly decreases, the sampling voltage UnA also decreases accordingly. When the power supply voltage DC+ is reduced to 0.5 times the rated voltage, the sampling voltage UnA is approximately 5V.

[0116] like Fig.10 As shown, in one embodiment, the control system of the trip unit further includes a rectifier and filter circuit.

[0117] The output end of the rectifier and filter circuit is electrically connected to the input end of the sampling circuit and the input end of the power supply circuit respectively to output a power supply voltage DC+.

[0118] Among them, Fig.11 As shown, the rectification and filtering circuit includes a varistor RV101, a rectifier diode D101, a rectifier diode D102, a rectifier diode D103, a rectifier diode D104 and a filtering capacitor CE101.

[0119] Among them, the rectifier and filter circuit absorbs the AC power (L, N) connected to the terminal P1 through the varistor RV101 and filters it through the full-wave rectifier unit composed of the rectifier diode D101, the rectifier diode D102, the rectifier diode D103, and the rectifier diode D104, and can generate a power supply voltage DC+ of about 300V.

[0120] In a third aspect, in one embodiment, the present invention provides a circuit breaker, including a trip unit and a control system of the trip unit in any one of the above embodiments.

[0121] Through the above circuit breaker, a first operational amplifier, a first feedback adjustment module and a second feedback adjustment module are arranged. With the first operational amplifier as the core, the first feedback adjustment module and the second feedback adjustment module respectively adjust the first voltage output to the first input terminal and the second voltage output to the second input terminal of the first operational amplifier according to the output of the first operational amplifier, so that the first operational amplifier finally outputs a PWM voltage to the first switching device, thereby realizing the driving of the release by PWM driving. Firstly, it can affect the power-on condition of the release, avoid the release from working for a long time, reduce the heat generation, and is not easy to burn the release, thereby reducing the safety hazard. Secondly, a release with a small number of turns and a small equivalent resistance can be used for work, thereby reducing the cost of the release.

[0122] The above is a detailed introduction to an insulation detection circuit and a circuit breaker system provided by the present invention. Specific examples are used in this article to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

[0123] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A coil driving circuit, characterized in that: The coil driving circuit includes a first operational amplifier, a first switching device, a first feedback regulation module and a second feedback regulation module; The first feedback regulation module includes a power supply terminal for connecting to a first working voltage, a feedback terminal electrically connected to the output terminal of the first operational amplifier and the controlled terminal of the first switching device respectively, and an output terminal electrically connected to the first input terminal of the first operational amplifier; The first access terminal and the second access terminal of the first switch device are connected in series with the release coil, and are used to control the current of the release coil; The second feedback regulation module includes a feedback end electrically connected to the output end of the first operational amplifier and an output end electrically connected to the second input end of the first operational amplifier; The first operational amplifier is used for outputting a PWM voltage to the first switching device through its output terminal according to a first voltage at its first input terminal and a second voltage at its second input terminal.

2. The coil driving circuit according to claim 1, characterized in that: The first feedback regulation module includes a first voltage-dividing resistor, a second voltage-dividing resistor and a third voltage-dividing resistor; The first end of the first voltage-dividing resistor is used to connect to the first working voltage, the second end of the first voltage-dividing resistor is electrically connected to the first end of the second voltage-dividing resistor, the first end of the third voltage-dividing resistor and the in-phase input terminal of the first operational amplifier, the second end of the second voltage-dividing resistor is used to be grounded, and the second end of the third voltage-dividing resistor is electrically connected to the output terminal of the first operational amplifier and the controlled terminal of the first switching device.

3. The coil driving circuit according to claim 1, characterized in that: The first feedback regulation module includes a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor and a second switch device; The first end of the first voltage-dividing resistor and the first end of the third voltage-dividing resistor are respectively used to access the first working voltage, the second end of the first voltage-dividing resistor is respectively electrically connected to the first end of the second voltage-dividing resistor, the first access end of the second switch device and the in-phase input end of the first operational amplifier, the second end of the second voltage-dividing resistor is used to be grounded, the second end of the third voltage-dividing resistor is electrically connected to the second access end of the second switch device, and the controlled end of the second switch device is respectively electrically connected to the output end of the first operational amplifier and the controlled end of the first switch device.

4. The coil driving circuit according to claim 2 or 3, characterized in that: The second feedback regulation module includes a capacitor, a first charge-discharge resistor and a second charge-discharge resistor; The first end of the capacitor is electrically connected to the inverting input end of the first operational amplifier and the first end of the first charge-discharge resistor, respectively; the second end of the first charge-discharge resistor is electrically connected to the output end of the first operational amplifier, the controlled end of the first switching device and the first end of the second charge-discharge resistor, respectively; the second end of the capacitor and the second end of the second charge-discharge resistor are used for grounding, respectively.

5. The coil driving circuit according to claim 4, characterized in that: The second feedback regulation module also includes an isolation diode; The cathode of the isolation diode is electrically connected to the second end of the first charge-discharge resistor and the first end of the second charge-discharge resistor respectively, and the anode of the isolation diode is electrically connected to the output end of the first operational amplifier and the controlled end of the first switch device respectively.

6. The coil driving circuit according to claim 2 or 3, characterized in that: The second feedback regulation module includes a capacitor, a first charge-discharge resistor and a second charge-discharge resistor; The first end of the capacitor is electrically connected to the inverting input end of the first operational amplifier and the first end of the first charge and discharge resistor respectively, the second end of the first charge and discharge resistor is electrically connected to the first access end of the first switching device and the first end of the second charge and discharge resistor respectively, and the second end of the capacitor and the second end of the second charge and discharge resistor are used for grounding respectively.

7. The coil driving circuit according to claim 6, characterized in that: The second feedback regulation module also includes a clamping diode; The anode of the clamping diode is electrically connected to the second end of the first charge-discharge resistor, the first end of the second charge-discharge resistor and the first access end of the first switch device respectively, and the cathode of the clamping diode is used for grounding.

8. A control system for a trip device, characterized in that: The controller of the release comprises an undervoltage control circuit and a coil drive circuit according to any one of claims 1 to 7; The power supply terminal of the undervoltage control circuit is used to access the second working voltage, the input terminal of the undervoltage control circuit is used to access the sampling voltage of the power supply, and the output terminal of the undervoltage control circuit is electrically connected to the power supply terminal of the first feedback regulation module; The undervoltage control circuit is used for outputting the first operating voltage to the first feedback regulation module when the sampled voltage is greater than a preset voltage.

9. The control system of the release according to claim 8, characterized in that: The undervoltage control circuit includes a first voltage stabilizing diode, a second operational amplifier, a fourth voltage dividing resistor and a PNP transistor; The cathode of the first voltage-regulating diode is respectively electrically connected to the in-phase input terminal of the second operational amplifier and the first end of the fourth voltage-dividing resistor and is used to access the second working voltage, the anode of the first voltage-regulating diode is used to be grounded, the inverting input terminal of the second operational amplifier is used to access the sampling voltage, the second end of the fourth voltage-dividing resistor is respectively electrically connected to the output terminal of the second operational amplifier and the base of the PNP type transistor, the emitter of the PNP type transistor is used to access the second working voltage, and the collector of the PNP type transistor is electrically connected to the power supply terminal of the first feedback regulation module.

10. The control system of the release according to claim 8, characterized in that: The control system of the release also includes a power supply circuit and a sampling circuit; The input end of the power supply circuit and the input end of the sampling circuit are respectively used to access the power supply voltage, the output end of the power supply circuit is electrically connected to the power supply end of the undervoltage control circuit, and the output end of the sampling circuit is electrically connected to the input end of the undervoltage control circuit.

11. The control system of the release according to claim 10, characterized in that: The power supply circuit includes an NPN transistor and a second voltage stabilizing diode; The collector of the NPN transistor, the base of the NPN transistor and the cathode of the second zener diode are respectively used to access the power supply voltage, the emitter of the NPN transistor is electrically connected to the power supply end of the undervoltage control circuit, and the anode of the second zener diode is used for grounding.

12. The control system according to claim 10, characterized in that: The sampling circuit includes a fifth voltage-dividing resistor and a sixth voltage-dividing resistor; The first end of the fifth voltage-dividing resistor is used to access the power supply voltage, the second end of the fifth voltage-dividing resistor is electrically connected to the first end of the sixth voltage-dividing resistor and the input end of the undervoltage control circuit respectively, and the second end of the sixth voltage-dividing resistor is used to be grounded.

13. A circuit breaker, characterized in that: A control system comprising a release and the release according to any one of claims 8 to 12.

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