Interface circuit for preventing starting peak

Abstract

The utility model discloses an interface circuit for preventing a starting peak, which relates to the field of starting peak processing, is characterized in that the interface circuit is arranged between a power supply and a load, and comprises a peak voltage preventing device, a PTC (Positive Temperature Coefficient) thermistor and a relay, the anti-peak voltage device is connected between a power supply positive electrode and a power supply negative electrode, the PTC thermistor and the relay are connected in parallel to form an assembly, and two ends of the assembly are respectively connected with the power supply negative electrode and a load negative electrode; the initial state of the relay is an off state. According to the utility model, the peak voltage is absorbed and inhibited through the cooperative use of the peak voltage prevention device and the PTC thermistor, and when the resistance value of the PTC thermistor is large enough, the non-peak starting can be basically realized. According to the utility model, the PTC thermistor is connected between the negative electrode of the power supply and the negative electrode of the load, so that the PTC thermistor and the load can be effectively prevented from forming partial pressure when the equipment is started, and the influence of the PTC thermistor on the load is reduced.

Description

Technical Field

[0001] The utility model relates to the field of starting spike processing, and more specifically, to an interface circuit for preventing starting spikes. Background Art

[0002] In electronic products, especially in inductive circuits, the sudden connection of the power supply in the circuit or the sudden access of loads such as motors will form transient spike voltages in the circuit, and arcing is likely to occur, which may cause irreversible performance degradation or damage to the components or loads in the circuit. Therefore, in order to prevent the equipment from malfunctioning or having safety hazards during use, it is usually necessary to add protection measures against spike voltages at the interface.

[0003] Commonly used spike voltage protection devices include transient voltage suppression diodes (TVS tubes), varistors and other components, but their clamping voltages and residual voltages are relatively high, and they can only provide a certain degree of protection and cannot fully ensure the safety of the equipment.

[0004] Chinese Patent CN209994580U provides a spike voltage elimination circuit, which includes a sampling module for sampling a voltage signal and generating a first output signal based on the voltage signal; a signal processing module, the signal processing module is coupled to the sampling module for comparing the first output signal with a reference voltage signal and outputting a comparison result signal; a switching module, the switching module is coupled to the signal processing module for conducting according to the comparison result signal to make the current of the voltage signal flow through a shunt circuit; and a timing module, the timing module is coupled to the input end and the output end of the signal processing module and is used to control the conduction time of the switching module. This spike voltage elimination circuit can reduce or eliminate the spike voltage on the components in the circuit, but its structure is complex and there is room for further simplification. Summary of the Utility Model

[0005] Aiming at the problems that the clamping voltage and residual voltage of the existing spike voltage protection devices are relatively high and the protection degree against starting spikes is limited, and the structure of the existing spike voltage elimination circuit is complex, the purpose of the utility model is to provide an interface circuit for preventing starting spikes, which is installed between the power supply and the load, and includes a spike voltage protection device, a PTC thermistor and a relay. The spike voltage protection device is any one of a TVS tube, a varistor and a gas discharge tube; the positive pole of the power supply is connected to the positive pole of the load, the spike voltage protection device is connected between the positive pole and the negative pole of the power supply, the PTC thermistor and the relay are connected in parallel as a component, and both ends of the component are respectively connected to the negative pole of the power supply and the negative pole of the load; the relay is in an open state initially.

[0006] The utility model is further arranged as: the spike voltage protection device is a TVS tube.

[0007] The present utility model is further configured such that: the TVS tube is a bidirectional TVS tube.

[0008] The present utility model is further configured such that: it further includes a diode, and the diode is connected between the positive electrode of the power supply and the positive electrode of the load.

[0009] The present utility model is further configured such that: it further includes a single-chip microcomputer, and the relay is connected to the single-chip microcomputer; the single-chip microcomputer is used to collect the working state signal of the load, and the working state signal is any one of a current signal and a voltage signal; a preset working signal range and a preset time are stored in the single-chip microcomputer; when the working state signal continuously remains within the preset working signal range within the preset time, the single-chip microcomputer controls the relay to pull in.

[0010] The present utility model is further configured such that: when the working state signal is a current signal, a current sensor is connected between the single-chip microcomputer and the load; when the working state signal is a voltage signal, an ADC module is provided inside the single-chip microcomputer, or a voltage sensor is connected between the single-chip microcomputer and the load.

[0011] The present utility model is further configured such that: the PTC thermistor is connected to the single-chip microcomputer, and the single-chip microcomputer is connected to the power supply; the single-chip microcomputer is used to measure the resistance value of the PTC thermistor and convert the resistance value of the PTC thermistor into the temperature of the PTC thermistor; a set dangerous temperature is stored in the single-chip microcomputer; when the temperature of the PTC thermistor is greater than or equal to the dangerous temperature, the single-chip microcomputer controls the power supply to stop supplying power to the load.

[0012] The present utility model is further configured such that: the temperature coefficient of the PTC thermistor is greater than or equal to 2 J / K.

[0013] The present utility model is further configured such that: the thermal time constant of the PTC thermistor is less than or equal to 100 s.

[0014] The present utility model is further configured such that: the maximum resistance value of the PTC thermistor is greater than 10 7 Ω.

[0015] In summary, the utility model has the following beneficial effects compared with the prior art: the utility model absorbs and suppresses the spike voltage through the cooperation of the anti-spike voltage device and the PTC thermistor. When the resistance value of the PTC thermistor is large enough, spike-free startup can be basically achieved. In the utility model, the PTC thermistor is connected between the negative pole of the power supply and the negative pole of the load, which can effectively avoid the voltage division between the PTC thermistor and the load when the device starts, and reduce the influence of the PTC thermistor on the load. In addition, the utility model also sets a single-chip microcomputer to realize the monitoring function of the load working state, so as to automatically control the suction of the relay. The single-chip microcomputer also has a temperature monitoring function, which can automatically control the power off to protect the load. Finally, the utility model also sets a diode as reverse polarity protection to further protect the load. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the overall structure diagram of the embodiment;

[0017] Figure 2 is the working flow chart of the single-chip microcomputer in the embodiment;

[0018] Figure 3 is the spike voltage waveform when there is no anti-startup spike interface circuit between the load and the power supply;

[0019] Figure 4 is the spike voltage waveform when there is an anti-startup spike interface circuit recorded in the embodiment between the load and the power supply.

[0020] In the figure: 1. Anti-spike voltage device; 2. PTC thermistor; 3. Relay; 4. Single-chip microcomputer; 5. Diode. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solution of the present utility model will be clearly described below in conjunction with the accompanying drawings. Obviously, the described embodiments are not all embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the utility model.

[0022] It should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "horizontal", "left", "right", "front", "rear", "lateral", "longitudinal", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present utility model.

[0023] Embodiment

[0024] As Figure 1-2As shown, this is a preferred embodiment of the present utility model. This embodiment provides an interface circuit for preventing startup spikes, which is installed between a power supply and a load, and the power supply and the load are not shown in the figure. This embodiment includes a spike voltage prevention device 1, a PTC thermistor 2, and a relay 3. The spike voltage prevention device 1 is any one of a TVS tube, a varistor, and a gas discharge tube. The positive pole of the power supply is connected to the positive pole of the load. The spike voltage prevention device 1 is connected between the positive pole and the negative pole of the power supply. The PTC thermistor 2 is also called a positive temperature coefficient thermistor. The PTC thermistor 2 and the relay 3 are connected in parallel as a component, and both ends of the component are respectively connected to the negative pole of the power supply and the negative pole of the load; the relay 3 is in an open state initially.

[0025] When the power supply is connected to the above circuit or the power switch is toggled, the generated startup spike voltage is absorbed for the first time by the spike voltage prevention device 1. Subsequently, the current flows through the PTC thermistor 2, and the temperature of the PTC thermistor 2 increases, and the resistance value of the PTC thermistor 2 increases, suppressing the remaining spike voltage. When the resistance value of the PTC thermistor 2 is large enough, spike-free startup can be basically achieved. However, at this time, the PTC thermistor 2 continues to generate heat and is prone to high-temperature danger. Therefore, after the load reaches the normal working state, it is necessary to control the relay 3 to close, so that the current flows through the relay 3, the current at the PTC thermistor 2 decreases, and the temperature of the PTC thermistor 2 decreases accordingly until the current is completely switched to the branch where the relay 3 is located. In this embodiment, the PTC thermistor 2 is connected between the negative pole of the power supply and the negative pole of the load, which can effectively prevent the PTC thermistor 2 from forming a voltage division with the load when the device starts, reducing the influence of the PTC thermistor 2 on the load.

[0026] In this embodiment, the spike voltage prevention device 1 is a TVS tube. The TVS tube is divided into a unidirectional TVS tube and a bidirectional TVS tube. The unidirectional TVS tube is only used to protect the forward voltage overload of the power supply, and the bidirectional TVS tube can protect the forward and reverse voltage overloads of the power supply. In this embodiment, the TVS tube is a bidirectional TVS tube.

[0027] This embodiment also includes a diode 5, which is connected between the positive pole of the power supply and the positive pole of the load as reverse polarity protection to prevent the current from flowing reversely into the load when the power supply polarity is wrongly connected, thereby protecting the load from damage.

[0028] This embodiment further includes a single-chip microcomputer 4. The PTC thermistor 2 is connected to the single-chip microcomputer 4, and the single-chip microcomputer 4 is connected to the power supply. The single-chip microcomputer 4 is used to measure the resistance value of the PTC thermistor 2 and convert the resistance value of the PTC thermistor 2 into the temperature of the PTC thermistor 2. A set dangerous temperature is stored in the single-chip microcomputer 4. When the temperature of the PTC thermistor 2 is greater than or equal to the dangerous temperature, the single-chip microcomputer 4 controls the power supply to stop supplying power to the load to protect the load. The measurement step of the temperature of the PTC thermistor 2 is: converting the resistance value of the thermistor into a digital signal through the ADC module inside the single-chip microcomputer 4, and combining the temperature coefficient of the PTC thermistor 2 stored inside the single-chip microcomputer 4 and the resistance value of the PTC thermistor 2 at room temperature to calculate the temperature of the PTC thermistor 2.

[0029] Specifically, the relay 3 is connected to the single-chip microcomputer 4. The single-chip microcomputer 4 is used to collect the working state signal of the load, and the working state signal is any one of a current signal and a voltage signal. A preset working signal range and a preset time are stored in the single-chip microcomputer 4. The initial state of the relay 3 is off. When the working state signal continuously stays within the preset working signal range within the preset time, it is determined that the load is in a stable working state, and the single-chip microcomputer 4 controls the relay 3 to close.

[0030] Specifically, when the working state signal is a current signal, a current sensor is connected between the single-chip microcomputer 4 and the load. When the working state signal is a voltage signal, an ADC module is provided inside the single-chip microcomputer 4, or a voltage sensor is connected between the single-chip microcomputer 4 and the load. The current sensor and the voltage sensor are not shown in the figure.

[0031] Specifically, the temperature coefficient of the PTC thermistor 2 is greater than or equal to 2 J / K to ensure that the PTC thermistor 2 has a high sensitivity to temperature changes.

[0032] Specifically, the thermal time constant of the PTC thermistor 2 is less than or equal to 100 s so that the PTC thermistor 2 can respond to temperature changes faster.

[0033] Specifically, the maximum resistance value of the PTC thermistor 2 is greater than 107 Ω to improve the current blocking effect of the PTC thermistor 2 and strengthen the suppression effect of the PTC thermistor 2 on the remaining peak voltage.

[0034] In this embodiment, the PTC thermistor 2 can select the PTC thermistors 2 with the numbers B59412C1130B070 and B59451C1130B070 produced by TDK Corporation. As Figure 3 shown, it is the peak voltage waveform without this embodiment between the load and the power supply; as Figure 4As shown, there is a spike voltage waveform of this embodiment between the load and the power supply; Figure 3 and Figure 4 in which the abscissa is time t with the unit of s, and the ordinate is the spike voltage U with the unit of V. According to Figure 3 and Figure 4 it can be known that this embodiment has a good suppression effect on the startup spike.

[0035] In summary, in this embodiment, the spike voltage is absorbed and suppressed through the combined use of the anti-spike voltage device 1 and the PTC thermistor 2. When the resistance value of the PTC thermistor 2 is large enough, spike-free startup can be basically achieved. In this embodiment, the PTC thermistor 2 is connected between the negative pole of the power supply and the negative pole of the load, which can effectively avoid the formation of voltage division between the PTC thermistor 2 and the load when the device starts up, and reduce the influence of the PTC thermistor 2 on the load. In addition, this embodiment also sets a single-chip microcomputer 4 to implement the load working state monitoring function to automatically control the closing of the relay 3. The single-chip microcomputer 4 also has a temperature monitoring function and can automatically control the shutdown of the power supply to protect the load. Finally, this embodiment also sets a diode 5 as reverse polarity protection to further protect the load.

[0036] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. An interface circuit for preventing startup spikes, characterized in that: Installed between a power source and a load, it comprises an anti-spike voltage device (1), a PTC thermistor (2) and a relay (3), wherein the anti-spike voltage device (1) is any one of a TVS tube, a varistor and a gas discharge tube; The positive electrode of the power supply is connected to the positive electrode of the load, the anti-spike voltage device (1) is connected between the positive electrode of the power supply and the negative electrode of the power supply, the PTC thermistor (2) and the relay (3) are connected in parallel to form a component, and the two ends of the component are respectively connected to the negative electrode of the power supply and the negative electrode of the load; the relay (3) is initially disconnected.

2. The interface circuit for preventing startup spikes according to claim 1, characterized in that: The anti-spike voltage device (1) is a TVS tube.

3. The interface circuit for preventing startup spikes according to claim 2, characterized in that: The TVS tube is a bidirectional TVS tube.

4. The interface circuit for preventing startup spikes according to claim 1, characterized in that: It also comprises a diode (5), wherein the diode (5) is connected between the positive electrode of the power supply and the positive electrode of the load.

5. An interface circuit for preventing startup spikes according to any one of claims 1 to 4, characterized in that: The device further comprises a single chip microcomputer (4), the relay (3) being connected to the single chip microcomputer (4); the single chip microcomputer (4) being used to collect a working state signal of a load, the working state signal being any one of a current signal and a voltage signal; the single chip microcomputer (4) storing a preset working signal range and a preset time; when the working state signal is continuously within the preset working signal range within the preset time, the single chip microcomputer (4) controls the relay (3) to be attracted.

6. The interface circuit for preventing startup spikes according to claim 5, characterized in that: When the working state signal is a current signal, a current sensor is connected between the single-chip microcomputer (4) and the load; when the working state signal is a voltage signal, an ADC module is provided inside the single-chip microcomputer (4), or a voltage sensor is connected between the single-chip microcomputer (4) and the load.

7. The interface circuit for preventing startup spikes according to claim 5, characterized in that: The PTC thermistor (2) is connected to the single-chip microcomputer (4), and the single-chip microcomputer (4) is connected to the power supply; the single-chip microcomputer (4) is used to measure the resistance value of the PTC thermistor (2) and convert the resistance value of the PTC thermistor (2) into the temperature of the PTC thermistor (2); the single-chip microcomputer (4) stores a set dangerous temperature; when the temperature of the PTC thermistor (2) is greater than or equal to the dangerous temperature, the single-chip microcomputer (4) controls the power supply to stop supplying power to the load.

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