A protection circuit and a charger

Abstract

The utility model relates to a protection circuit and a charger, the protection circuit comprising: a power module; a first switch module; a protection module connected to the first switch module, the protection module comprising a second switch module and a protection resistor; a detection module connected to a target acquisition point, used to detect a target voltage at the target acquisition point after the first switch module is closed; a first control module connected to the first switch module, used to control the first switch module to close according to a first control signal sent by a processor, so that the protection resistor is connected to the protection circuit; a second control module connected to the second switch module, used to control the second switch module to close according to a second control signal sent by the processor, so that the protection resistor is short-circuited, wherein the second control signal is generated based on the target voltage detected by the detection module. The utility model can not only fundamentally eliminate arc phenomenon, but also reduce power loss, and the control is more precise, and the system integration is higher.

Description

[Technical field]

[0001] The utility model relates to the field of relays, in particular to a protection circuit and a charger. [Background Technology]

[0002] Relays are widely used in automation control. At the moment when the relay switches state, due to the high voltage difference between the two ends of the relay, the contacts of the relay will break through the air to generate an arc. The high temperature of the arc will often damage the switch contacts of the relay and shorten the service life of the relay.

[0003] To address this problem, the existing technology limits the current by connecting a thermistor in series in the loop. Although this protection circuit has a simple structure and can eliminate arcing, as the number of protection times increases, the thermistor will gradually become high-resistance, or even generate heat and burn, causing a certain amount of power loss, and has low safety. [Contents of the utility model]

[0004] In view of this, it is necessary to provide a protection circuit that can fundamentally eliminate the arc phenomenon of the relay without causing additional power loss.

[0005] The utility model provides a protection circuit, which comprises:

[0006] A power module, used for inputting electric energy to the protection circuit;

[0007] A first switch module, wherein an input end of the first switch module is connected to the power module, and an output end of the first switch module is connected to the protection module, and is used to close or open according to whether the power module is connected;

[0008] A protection module, the input end of which is connected to the first switch module, and is used to eliminate arcing generated during the closing process of the first switch module; wherein the protection module includes a second switch module and a protection resistor;

[0009] a first control module, wherein an output end of the first control module is connected to the first switch module, and is used to control the first switch module to be closed according to a first control signal sent by the processor, so that the protection resistor is connected to the protection circuit;

[0010] A detection module, the input end of which is connected to the target collection point, and is used to detect the target voltage at the target collection point after the first switch module is closed;

[0011] A second control module, wherein the output end of the second control module is connected to the second switch module, and is used to control the second switch module to close according to a second control signal sent by the processor so as to short-circuit the protection resistor, wherein the second control signal is generated based on the target voltage detected by the detection module.

[0012] Furthermore, the power supply module includes an AC power supply for inputting AC power to the protection circuit.

[0013] Furthermore, the protection circuit also includes a rectifier module, the input end of the rectifier module is connected to the output end of the protection module, and is used to convert the alternating current input by the power module into direct current.

[0014] Furthermore, the protection circuit also includes a power factor correction module, the input end of the power factor correction module is connected to the output end of the rectifier module, and is used to control the current waveform of the direct current and improve the power factor of the power supply.

[0015] Furthermore, the processor at least includes a first input port; the first input port of the processor is connected to the output end of the detection module for receiving the target voltage; and the processor generates a second control signal according to the target voltage.

[0016] Furthermore, the first control signal is a digital signal, wherein if it is detected that the power module is connected, the processor generates a first control signal; the second control signal is a digital signal, wherein if it is detected that the target voltage reaches a preset value, the processor generates a second control signal.

[0017] Furthermore, the processor includes at least a first output port and a second output port; the first output port of the processor is connected to the input end of the first control module, and is used to send a first control signal to the first control module; the second output port of the processor is connected to the input end of the second control module, and is used to send a second control signal to the second control module.

[0018] Further, the first control module includes a first trigger element, and the first control module controls the conduction of the first trigger element based on a first control signal to close the first switch module; the second control module includes a second trigger element, and the second control module controls the conduction of the second trigger element based on a second control signal to close the second switch module.

[0019] Furthermore, the first trigger element at least includes a triode or a MOS tube; the second trigger element at least includes a triode or a MOS tube.

[0020] The utility model also provides a charger, which comprises the above protection circuit.

[0021] Compared with the prior art, the scheme adopted by the utility model has the following beneficial effects: at the moment when the power module is connected, the first switch module is controlled to close and the current is limited by the protection resistor; after accurately detecting that the voltage at the target point reaches the preset value, the second switch module is controlled to close and the protection resistor is short-circuited; it can not only fundamentally eliminate the arc phenomenon, but also reduce power loss, and determine whether the voltage difference on the main circuit meets the conditions for generating an arc based on the relationship between the detected voltage value and the preset value, and use a processor to control the entire protection circuit, so that the control is more precise and the system integration is high. [Drawings]

[0022] Figure 1 It is a structural schematic diagram of the protection circuit of the utility model;

[0023] Figure 2 It is a circuit diagram of the protection circuit of the utility model;

[0024] Figure 3 It is a structural schematic diagram of the processor of the utility model. [Specific implementation method]

[0025] The terms used in the utility model are only for the purpose of describing specific embodiments, and are not intended to limit the utility model. For example, the following words indicating orientation or positional relationship, such as "upper", "lower", "front", "back", etc., are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the device / element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the utility model.

[0026] In the process of implementing the present application, the inventor discovered that at the moment when the relay switches state, due to the high voltage difference between the two ends of the relay, the contacts of the relay will break through the air to generate an arc, and the high temperature of the arc will often damage the switch contacts of the relay and shorten the service life of the relay.

[0027] In the current technical solution, the current is limited by connecting a thermistor in series in the power control loop. Although this protection circuit has a simple structure and can eliminate arcing, it has a certain power loss and is relatively safe.

[0028] In view of the above problems, a protection circuit is provided in an embodiment of the present application, which reduces power loss while eliminating arcing of the relay.

[0029] In order to make the technical solutions and advantages in the embodiments of the present application more clearly understood, the following will describe the exemplary embodiments in conjunction with the accompanying drawings. It should be noted that the components depicted in the reference drawings are not necessarily shown to scale; and the same or similar components will be given the same or similar reference numerals or similar technical terms.

[0030] See also Figure 1 The protection circuit provided in the embodiment of the present application includes: a processor 101, a power module 102, a first switch module 103, a protection module 104, a first control module 105, a rectifier module 106, a power factor correction module 107, a detection module 108 and a second control module 109, wherein:

[0031] The processor 101 in an optional embodiment is used to receive a detection signal from the protection circuit, generate a control signal and send a corresponding control signal to the protection circuit. The processor 101 includes at least a first input port, a first output port and a second output port.

[0032] In an optional embodiment, the first input port of the processor 101 is connected to the output end of the detection module 108, and is used to receive the detection result of the detection module 108; the first output port of the processor 101 is connected to the input end of the first control module 105, and is used to send a first control signal to the first control module 105; the second output port of the processor 101 is connected to the output end of the second control module 109, and is used to send a second control signal to the second control module 109. The processor 101 at least includes a single-chip microcomputer system. In the following embodiments, the processor 101 will be described as a single-chip microcomputer system. Of course, the processor may also include other programmable control systems.

[0033] For details, see Figure 2 and Figure 3 The first input port of the single-chip microcomputer system is the PFC_FB pin of the single-chip microcomputer system, the first output port of the single-chip microcomputer system is the K1 pin of the single-chip microcomputer system, and the second output port of the single-chip microcomputer system is the K2 pin of the single-chip microcomputer system.

[0034] The power module 102 in the optional embodiment is used to input electrical energy to the protection circuit.

[0035] In an optional embodiment, the power supply module 102 includes: an AC power supply or a DC power supply. If it is an AC power supply, the power supply module is used to input AC power to the protection circuit.

[0036] In the first switch module 103 in the optional embodiment, the input end of the first switch module 103 is connected to the power module 102, and the output end of the first switch module 103 is connected to the protection module 104, which is used to close or open the main circuit according to whether the power module 102 is connected.

[0037] In an optional embodiment, the first switch module 103 includes at least a first relay;

[0038] For details, see Figure 2 The first switch module 103 is a first relay K1. The first end of the contact switch of the first relay K1 is connected to the power module 102, and the other end is connected to the protection module 104. When the power module 102 is connected, the first relay K1 is controlled to be closed. When the power module 102 is disconnected, the first relay K1 is controlled to be disconnected.

[0039] In the protection module 104 in the optional embodiment, the input end of the protection module 104 is connected to the first switch module 103 to eliminate the arc phenomenon generated when the first switch module 103 is closed.

[0040] In an optional embodiment, the protection module 104 includes a second switch module and a protection resistor, and the second switch module includes at least a second relay.

[0041] For details, see Figure 2 , the protection module 104 includes a second relay K2 and a protection resistor R3, the contact switch of the second relay K2 and the protection resistor R3 are connected in parallel, and the contact switch of the second relay K2 is connected in series with the contact switch of the first relay K1. It can be understood that the function of the protection resistor R3 is: when the first relay K1 is closed, the protection resistor R3 limits the current of the main circuit, thereby preventing a large current from impacting the switch contact of the first relay K1, causing the first relay K1 to generate an arc.

[0042] In the first control module 105 of an optional embodiment, the output end of the first control module 105 is connected to the first switch module 103, and is used to control the first switch module 103 to close according to the first control signal received from the first output port of the single-chip computer system, so that the protection resistor R3 is connected to the protection circuit for current limiting.

[0043] In an optional embodiment, the first control signal is a digital signal, and the digital signal is a high level. If it is detected that the power module 102 is connected, the single-chip microcomputer system generates a first control signal and sends the first control signal to the first control module 105 through the first output port.

[0044] In an optional embodiment, the first control module 105 includes a first trigger element. The first control module 105 controls the conduction of the first trigger element based on a first control signal, and the first switch module 103 is closed by conducting the first trigger element.

[0045] In an optional embodiment, the first trigger element includes at least a controllable switch element such as a transistor or a MOS tube. The embodiment of the present application will be exemplified by taking the first trigger element as a transistor as an example, but it does not mean that the present invention is limited to this.

[0046] For details, see Figure 2 The first trigger element is a first transistor Q1, and the first control module 105 includes a first resistor R1, a second resistor R2, a first capacitor C1, a first transistor Q1 and a first diode D1, wherein the base of the first transistor Q1 is connected to the first output port of the single-chip computer system through the second resistor R2, the collector is connected to the coil end of the first relay K1 through the diode D1, and the emitter is grounded; wherein the first diode D1 is a freewheeling diode, which can prevent the high voltage generated at both ends of the coil from damaging the circuit when the coil of the first relay K1 is disconnected; the first resistor R1 is a pull-down resistor, the second resistor R2 is a current limiting resistor, and the first capacitor C2 is a bypass capacitor.

[0047] When the power module 102 is connected to the protection circuit, the first output port of the single-chip computer system generates a high-level signal and sends the high-level signal to the input end of the first control module 105. After the input end of the first control module 105 receives the high-level signal, it controls the first transistor Q1 to be turned on. At this time, the first relay K1 is closed, and the arc phenomenon of the first relay K1 is eliminated by connecting the protection resistor R3 and the first relay K1 in series in the main circuit to limit the current.

[0048] In the optional embodiment, the rectifier module 106 has an input end connected to the output end of the protection module 104 and is used to convert the alternating current input by the power module 102 into direct current.

[0049] In an optional embodiment, since a DC power supply needs to be provided for the load and the single-chip microcomputer system can only collect DC signals, a rectifier module 106 is provided.

[0050] For details, see Figure 2 The rectifier module 106 includes a rectifier BD1 and a filter capacitor C7. The rectifier BD1 is used to convert AC power into DC power. However, since the waveform output by the rectifier BD1 has a large voltage change, that is, a ripple voltage, the filter capacitor C7 is connected in parallel with the rectifier BD1 to smooth the output voltage ripple.

[0051] In the power factor correction module 107 in the optional embodiment, the input end of the power factor correction module 107 is connected to the output end of the rectifier module 106, and is used to control the current waveform of the direct current to improve the power factor of the power supply.

[0052] It is understandable that for the rectifier module 106, there is input current only when the AC voltage is greater than the voltage across the filter capacitor C7. This characteristic causes a phase shift between the AC input current and the output voltage, which greatly affects the power factor.

[0053] In an optional embodiment, a high-frequency inductor, a diode, a high-frequency switch tube and a corresponding controller are added to the input end to form a boost converter. The controller controls the switching on and off of the switch tube by collecting the voltage signal and current signal of the AC input, thereby improving the power factor.

[0054] For details, see Figure 2 The power factor correction module 107 includes a high-frequency inductor L3, a high-frequency switch tube Q3, a sixth resistor R6, a diode D4 and an electrolytic capacitor EC1. The on and off of the high-frequency switch tube Q3 is driven by the corresponding control chip. When the control chip drives the high-frequency switch tube Q3 to close, the high-frequency inductor L3 is charged by the voltage source output by the rectifier module; when the control chip drives the high-frequency switch tube Q3 to open, the high-frequency inductor L3 injects the previously stored current into the circuit to increase the output voltage, and also charges the electrolytic capacitor EC1. The electrolytic capacitor EC1 is responsible for maintaining the output voltage when the high-frequency inductor L3 is charged, so that the AC input current waveform always follows the input voltage waveform, thereby improving the power factor.

[0055] In the detection module 108 in the optional embodiment, the input end of the detection module 108 is connected to the target collection point, and is used to detect the target voltage at the target collection point after the first switch module 103 is closed.

[0056] For details, see Figure 2 The target acquisition point is located between the eighth resistor R8 and the ninth resistor R9. After the target voltage at the target acquisition point is detected, the target voltage is sent to the first input port of the single-chip microcomputer system, so that the single-chip microcomputer system can further determine whether to generate a second control signal to control the second relay K2 to close according to the target voltage value.

[0057] In the second control module 109 in an optional embodiment, the output end of the second control module 109 is connected to the second switch module, and is used to control the second switch module to close according to a second control signal sent by the second output port of the single-chip computer system, so as to short-circuit the protection resistor R3, wherein the second control signal is generated based on the target voltage detected by the detection module 108.

[0058] In an optional embodiment, the second control signal is a digital signal, and the digital signal can be generated according to a voltage signal, for example, a high-level signal, wherein if it is detected that the target voltage reaches a preset value, the single-chip microcomputer system generates the second control signal.

[0059] In an optional embodiment, the second control module 109 includes a second trigger element, and the second control module 109 controls the conduction of the second trigger element based on a second control signal to close the second switch module.

[0060] In an optional embodiment, the second trigger element includes at least a controllable switch element such as a transistor or a MOS tube. The embodiment of the present application will be exemplified by taking the second trigger element as a transistor as an example, but it does not mean that the present invention is limited to this.

[0061] For details, see Figure 2 The second trigger element is a second transistor Q2, and the second control module 109 includes a fourth resistor R4, a fifth resistor R5, a second capacitor C2, a second transistor Q2 and a second diode D2. The base of the second transistor Q2 is connected to the second output port of the single-chip computer system through the fourth resistor R4, the collector is connected to the coil end of the second relay K2 through the second diode D2, and the emitter is grounded; wherein, the diode D2 is a freewheeling diode, the fourth resistor R2 is a current limiting resistor, the fifth resistor R1 is a pull-down resistor, and the second capacitor C2 is a bypass capacitor.

[0062] When the first relay K1 is closed, as the charging process is prolonged, the pressure difference at both ends of the main circuit gradually decreases. If the pressure difference at both ends of the main circuit does not cause the relay switch to instantly generate an arc phenomenon, the existence of the protection resistor R3 will produce unnecessary power loss. In order to avoid this power loss, after the first input port of the single-chip computer system receives the target voltage detected by the detection module 108, if it is determined that the target voltage reaches the preset value, the second output port of the single-chip computer system generates a high level and sends the high level to the input port of the second control module 109. After receiving the high level, the second control module 109 controls the second transistor Q2 to turn on. At this time, the switch contact of the second relay K2 is closed, the protection resistor R3 is short-circuited, and no current flows through the protection resistor R3, thereby reducing power loss. After the protection resistor R3 is short-circuited, the first relay K1 and the second relay K2 are connected in series with each other, and the entire protection circuit can still work normally.

[0063] It is understandable that the size of the preset value can be customized according to actual conditions so that the protection circuit can be applied to chargers of different models and powers.

[0064] The present application also provides a charger, wherein the charger adopts the protection circuit as described above. The protection circuit has been described in detail above and will not be described again here.

[0065] The principle of the protection circuit provided by the present invention can be briefly described as follows: at the moment when the power module 102 is connected, the single-chip computer system controls the first relay K1 to close, and limits the current through the protection resistor R3 to prevent a large current from impacting the switch contacts of the first relay K1 so as to cause an arc phenomenon in the first relay K1; after accurately detecting that the voltage at the target point reaches a preset value, it is determined that no arc phenomenon will occur at this time, and the single-chip computer system then controls the second relay K2 to close, short-circuiting the protection resistor R3 to avoid unnecessary power loss and ensure the normal operation of the entire circuit.

[0066] Through the above protection circuit, the arc phenomenon can be fundamentally eliminated and the power loss can be reduced. The pressure difference on the main circuit can be determined based on the relationship between the detected voltage value and the preset value to determine whether the condition for the relay to generate an arc, making the control of the relay more precise. The on and off of multiple relays can be controlled by the single-chip microcomputer system, and the system integration is higher.

[0067] The utility model is not limited to the above specific implementations. Those skilled in the art can easily understand that there are many alternatives to the protection circuit of the utility model without departing from the principle and scope of the utility model. The protection scope of the utility model shall be based on the content of the claims.

Claims

1. A protection circuit, characterized in that: The protection circuit comprises: A power module, used for inputting electric energy to the protection circuit; A first switch module, wherein an input end of the first switch module is connected to the power module, and an output end of the first switch module is connected to the protection module, and is used to close or open according to whether the power module is connected; A protection module, the input end of which is connected to the first switch module, and is used to eliminate arcing generated during the closing process of the first switch module; wherein the protection module includes a second switch module and a protection resistor; a first control module, wherein an output end of the first control module is connected to the first switch module, and is used to control the first switch module to be closed according to a first control signal sent by the processor, so that the protection resistor is connected to the protection circuit; A detection module, the input end of which is connected to the target collection point, and is used to detect the target voltage at the target collection point after the first switch module is closed; A second control module, wherein the output end of the second control module is connected to the second switch module, and is used to control the second switch module to close according to a second control signal sent by the processor so as to short-circuit the protection resistor, wherein the second control signal is generated based on the target voltage detected by the detection module.

2. The protection circuit according to claim 1, characterized in that: The power supply module includes an AC power supply for inputting AC power to the protection circuit.

3. The protection circuit according to claim 2, characterized in that: The protection circuit further comprises a rectifier module, the input end of which is connected to the output end of the protection module, and is used for converting the alternating current input by the power module into direct current.

4. The protection circuit according to claim 3, characterized in that: The protection circuit also includes a power factor correction module, the input end of which is connected to the output end of the rectifier module, and is used to control the current waveform of the direct current and improve the power factor of the power supply.

5. The protection circuit according to claim 1, characterized in that: The processor comprises at least a first input port; The first input port of the processor is connected to the output end of the detection module for receiving the target voltage; The processor generates a second control signal according to the target voltage.

6. The protection circuit according to claim 5, characterized in that The first control signal is a digital signal, wherein if it is detected that the power module is connected, the processor generates the first control signal; The second control signal is a digital signal, wherein if it is detected that the target voltage reaches a preset value, the processor generates the second control signal.

7. The protection circuit according to claim 1, characterized in that: The processor comprises at least a first output port and a second output port; The first output port of the processor is connected to the input end of the first control module, and is used to send a first control signal to the first control module; The second output port of the processor is connected to the input end of the second control module and is used to send a second control signal to the second control module.

8. The protection circuit according to claim 1, characterized in that: The first control module includes a first trigger element, and the first control module controls the conduction of the first trigger element based on a first control signal to close the first switch module; The second control module includes a second trigger element. The second control module controls the conduction of the second trigger element based on a second control signal to close the second switch module.

9. The protection circuit according to claim 8, characterized in that: The first trigger element at least includes a triode or a MOS tube; The second trigger element at least includes a triode or a MOS tube.

10. A charger, characterized in that: The charger comprises the protection circuit according to any one of claims 1 to 9.

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