Current suppression circuit, system and method

Abstract

In the present invention, a current suppression circuit, system and method are provided. The current suppression circuit controls the on / off of the heating circuit in the PTC heater through a driving circuit according to a pulse driving signal with a preset duty ratio received. When the heating circuit is disconnected, the switching circuit controls the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitance, so that when the heating circuit is turned on, the voltage across the parasitic inductance is reduced and the current in the parasitic inductance is suppressed. In the present invention, the on / off of the heating circuit in the PTC heater is controlled by inputting a pulse driving signal with a preset duty ratio. When the heating circuit in the PTC heater is disconnected under the control of the pulse driving signal with the preset duty ratio, the parasitic inductance in the PTC heater charges the corresponding parasitic capacitance, thereby suppressing the current in the parasitic inductance when the heating circuit is turned on.

Description

Technical Field

[0001] The present invention relates to the field of heaters, and in particular, to a current suppression circuit, system and method. Background Art

[0002] With the improvement of people's living standards, the use of heaters has become more and more popular; among them, the PTC heater is composed of a PTC ceramic heating element and an aluminum tube. This type of PTC heater has the advantages of small thermal resistance, high heat exchange efficiency, automatic constant temperature, power saving, etc., and the PTC heater has gradually been favored by people.

[0003] Due to the parasitic inductance and parasitic capacitance existing in the heating resistance of the PTC heater, a very large current peak will occur when the PTC heater is turned on, which may cause damage to some components on the power supply loop, resulting in losses or even danger.

[0004] The above content is only used to assist in understanding the technical solution of the present invention, and does not represent an admission that the above content is prior art. Summary of the Invention

[0005] The main object of the present invention is to provide a current suppression circuit, system and method, aiming to solve the technical problem that a very large current peak appears when the PTC heater in the prior art is turned on.

[0006] To achieve the above object, the present invention proposes a current suppression circuit, and the current suppression circuit includes: a drive circuit and a switch circuit;

[0007] Wherein, the drive circuit is connected to the PTC heater, and the switch circuit is connected to the PTC heater;

[0008] The drive circuit is used to control the on / off of the heating circuit in the PTC heater according to the received pulse drive signal with a preset duty ratio;

[0009] The switch circuit is used to charge the parasitic capacitance corresponding to the parasitic inductance in the PTC heater when the heating circuit is disconnected, so as to reduce the voltage across the parasitic inductance and suppress the current in the parasitic inductance when the heating circuit is turned on.

[0010] Optionally, the current suppression circuit further includes: a current acquisition circuit and a control circuit;

[0011] Wherein, the current acquisition circuit is connected to the PTC heater through the drive circuit, and the control circuit is connected to the current acquisition circuit and the drive circuit;

[0012] The current acquisition circuit is used to acquire the real-time current value in the heating circuit of the PTC heater when the PTC heater is turned on, and send the real-time current value to the control circuit;

[0013] The control circuit is used to compare the real-time current value with the current limiting value, and generate a cut-off signal when the real-time current value is not less than the current limiting value, and output the cut-off signal to the drive circuit;

[0014] The drive circuit is further used to control the disconnection of the heating circuit of the PTC heater according to the cut-off signal when receiving the cut-off signal.

[0015] Optionally, the drive circuit includes IGBTs with the same number as the PTC heaters;

[0016] Wherein, the gate of the IGBT is connected to the control circuit, the collector of the IGBT is connected to the output end of the corresponding PTC heater, and the emitter of the IGBT is connected to the input end of the current acquisition circuit.

[0017] Optionally, the switch circuit includes: diodes with the same number as the PTC heaters;

[0018] Wherein, the positive pole of the diode is connected to the output end of the resistor in the corresponding PTC heater, and the negative pole of the diode is connected to the input end of the resistor in the corresponding PTC heater.

[0019] Optionally, the current acquisition circuit includes: current sampling resistors with the same number as the PTC heaters;

[0020] Wherein, the first end of the current sampling resistor is connected to the emitter of the corresponding IGBT, and the second end of the current sampling resistor is connected to the negative pole of the power supply.

[0021] Optionally, the current suppression circuit further includes: a filter circuit; the filter circuit includes: a filter capacitor;

[0022] Wherein, the first end of the filter capacitor is connected to the positive pole of the power supply and the input end of the PTC heater, and the output end of the filter capacitor is connected to the negative pole of the power supply and the second end of the current sampling resistor.

[0023] Optionally, the current suppression circuit further includes: a fuse and a contactor;

[0024] Among them, the first end of the fuse is connected to the positive pole of the power supply, the second end of the fuse is connected to the first end of the contactor, and the second end of the contactor is connected to the input end of the PTC heater and the first end of the filter capacitor.

[0025] To achieve the above object, the present invention further provides a current suppression system, and the current suppression system includes the above current suppression circuit.

[0026] To achieve the above object, based on the above current suppression system, the present invention further provides a current suppression method, and the current suppression method includes:

[0027] Controlling the on-off of the heating circuit of the PTC heater according to the pulse drive signal with the preset duty ratio;

[0028] When the heating circuit is disconnected, controlling the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitor, so that when the heating circuit is turned on, the voltage across the parasitic inductance is reduced, and the current in the parasitic inductance is suppressed.

[0029] Optionally, before the step of controlling the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitor when the heating circuit is disconnected, so that when the heating circuit is turned on, the voltage across the parasitic inductance is reduced, and the current in the parasitic inductance is suppressed, the method further includes:

[0030] When the PTC heater is turned on, collecting the real-time current value in the heating circuit of the PTC heater;

[0031] Comparing the real-time current value with the current limiting value, and generating a cut-off signal when the real-time current value is not less than the current limiting value;

[0032] Controlling the heating circuit of the PTC heater to be disconnected according to the cut-off signal.

[0033] In the present invention, a current suppression circuit, system and method are provided. The current suppression circuit controls the on-off of the heating circuit in the PTC heater through a drive circuit according to a pulse drive signal with a preset duty ratio; when the heating circuit is disconnected, the switching circuit controls the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitor, so that when the heating circuit is turned on, the voltage across the parasitic inductance is reduced, and the current in the parasitic inductance is suppressed. In the present invention, the on-off of the heating circuit in the PTC heater is controlled by inputting a pulse drive signal with a preset duty ratio. When the heating circuit in the PTC heater is disconnected under the control of the pulse drive signal with the preset duty ratio, the parasitic inductance in the PTC heater is charged with the corresponding parasitic capacitor, thereby suppressing the current in the parasitic inductance when the heating circuit is turned on. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0035] Figure 1 It is a schematic structural diagram of the first embodiment proposed for the current suppression circuit of the present invention;

[0036] Figure 2 It is a circuit structure diagram of the PTC heating resistor of the present invention;

[0037] Figure 3 It is a current waveform diagram when the PTC heater in the prior art is turned on;

[0038] Figure 4 It is a current waveform diagram when the PTC heater of the present invention is turned on;

[0039] Figure 5 It is a schematic structural diagram of the second embodiment proposed for the current suppression circuit of the present invention;

[0040] Figure 6 It is the first circuit diagram of the second embodiment proposed for the current suppression circuit of the present invention;

[0041] Figure 7 It is the second circuit diagram of the second embodiment proposed for the current suppression circuit of the present invention;

[0042] Figure 8 It is a schematic flow chart of the first embodiment proposed for the current suppression method of the present invention;

[0043] Figure 9 It is a schematic flow chart of the second embodiment proposed for the current suppression method of the present invention.

[0044] Description of the reference numerals in the drawings:

[0045] Label Name Label Name 10 Drive circuit R1 Resistor 20 Switching circuit L1 Parasitic inductance 30 Current acquisition circuit C1 Parasitic capacitance 40 Control circuit V PTC voltage 50 Filter circuit I PTC current C2 Filter capacitor S PTC drive signal DC Power supply D1 Diode F Fuse PCT PCT heater K Contactor R2 Current sampling resistor

[0046] The realization, functional features and advantages of the object of the present invention will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0047] It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0048] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0049] It should be noted that all directional indications (such as up, down, left, right, front, back...) in the embodiments of the present invention are only used to explain the relative positional relationship and movement conditions between components in a specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0050] In addition, the descriptions involving "first", "second", etc. in the present invention are only for descriptive purposes, and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the protection scope required by the present invention.

[0051] Refer to Figure 1 , Figure 1 is a schematic structural diagram of the first embodiment proposed for the current suppression circuit of the present invention. Based on Figure 1 , the first embodiment of the current suppression circuit of the present invention is proposed.

[0052] In this embodiment, the current suppression circuit includes: a drive circuit 10 and a switch circuit 20;

[0053] Among them, the drive circuit 10 is connected to the PTC heater, and the switch circuit 20 is connected to the PTC heater.

[0054] It should be noted that, referring to Figure 2 , the resistor in the existing high-power PTC heater is not an ideal resistor, and it is equivalent to having a parallel capacitor and a series inductor. Therefore, when using a switching tube to control the turn-on of the PTC heater, the initial voltage across the parasitic capacitor C1 is 0, and since the resistor in the PTC heater is in parallel with the capacitor, the voltage across the resistor is also 0. So the input high voltage is completely applied across the parasitic inductor L1. Since the power supply voltage is generally at the 10 2 level, and the parasitic inductor L1 is at the uH level, the current rising slope is extremely high. Refer to Figure 3, when the PTC voltage V is constant and the PTC drive signal S is input, the PTC current I can reach hundreds of amperes instantaneously. Then the capacitor continues to charge, the capacitor voltage gradually increases, and the voltage across the inductor gradually decreases until it becomes 0. The current no longer increases, and after a short oscillation, the current returns to its normal magnitude.

[0055] It should be understood that the drive circuit 10 is a circuit used to control the on-off of the heating circuit in the PTC heater. When the drive circuit 10 controls the heating circuit in the PTC heater, a certain pulse drive signal is required. The drive circuit 10 can control the on-off of the heating circuit by driving the on-off of relevant switching components in the heating circuit. The switch circuit 20 can be used to form a complete charging circuit for the parasitic capacitor C1 by combining the parasitic inductor L1 storing a certain amount of energy with the parasitic capacitor C1 with a voltage of 0 at both ends. Refer to Figure 4 , when the heating circuit is turned on again, since there is a certain voltage across the parasitic capacitor C1, the voltage value across the parasitic inductor L1 decreases, thereby reducing the current value in the parasitic inductor L1.

[0056] Among them, the pulse drive signal with a preset duty cycle is a pulse drive signal with a certain duty cycle preset in advance. The pulse drive signal with a preset duty cycle controls the heating circuit to conduct during the effective duty cycle time and controls the heating circuit to disconnect during the invalid duty cycle time. The pulse drive signal with a preset duty cycle can repeatedly control the heating circuit to conduct or cut off within the time of this pulse drive signal until the PTC heater starts up successfully. The duty cycle of the pulse drive signal can be set according to specific situations. A relatively large effective duty cycle of the pulse drive signal will result in an insignificant suppression of the current in the parasitic inductor L1, and a relatively small effective duty cycle of the pulse drive signal will cause the PTC heater to start up too slowly.

[0057] In a specific implementation, the drive circuit 10 can control the on-off of the heating circuit in the PTC heater according to the received pulse drive signal with a preset duty cycle; the switch circuit 20 can, when the heating circuit is disconnected, control the parasitic inductor L1 in the PTC heater to charge the corresponding parasitic capacitor C1, so that when the heating circuit is turned on, the voltage across the parasitic inductor L1 is reduced, and the current in the parasitic inductor L1 is suppressed. For example, when the effective duty cycle of the pulse drive signal with a preset duty cycle is 50%, the heating circuit conducts within 1 microsecond in the first half cycle and disconnects within 1 microsecond in the second half cycle, and the on-off of the heating circuit is controlled alternately until the startup is completed.

[0058] This embodiment provides a current suppression circuit. The current suppression circuit controls the on / off of the heating circuit in the PTC heater through a driving circuit according to a pulse driving signal with a preset duty ratio received. When the heating circuit is disconnected, the switching circuit controls the parasitic inductor L1 in the PTC heater to charge the corresponding parasitic capacitor C1, so that when the heating circuit is turned on, the voltage across the parasitic inductor L1 is reduced, and the current in the parasitic inductor L1 is suppressed. In this embodiment, the on / off of the heating circuit in the PTC heater is controlled by inputting a pulse driving signal with a preset duty ratio. When the heating circuit in the PTC heater is disconnected multiple times under the control of the pulse driving signal with the preset duty ratio, the parasitic inductor L1 in the PTC heater charges the corresponding parasitic capacitor C1, thereby suppressing the current in the parasitic inductor L1 when the heating circuit is turned on.

[0059] Refer to Figure 5 , Figure 5 FIG. is a schematic structural diagram of a second embodiment of the current suppression circuit of the present invention. Based on the first embodiment of the current suppression circuit of the present invention described above, a second embodiment of the current suppression circuit of the present invention is proposed.

[0060] In this embodiment, the current suppression circuit further includes: a current acquisition circuit 30 and a control circuit 40;

[0061] Wherein, the current acquisition circuit 30 is connected to the PTC heater through the driving circuit 10, and the control circuit 40 is connected to the current acquisition circuit 30 and the driving circuit 10.

[0062] It should be noted that the current acquisition circuit 30 can be used to acquire the current value in the heating circuit of the PTC heater, that is, to acquire the current value in the parasitic inductor L1. The control circuit 40 is a circuit for controlling the current in the heating circuit of the PTC heater. The control circuit 40 can control the driving circuit 10 to disconnect the heating circuit and stop the voltage input when the current value in the heating circuit of the PTC heater exceeds the current limiting value of the parasitic inductor L1.

[0063] In a specific implementation, when the PTC heater is turned on, the current acquisition circuit 30 acquires the real-time current value in the heating circuit of the PTC heater and sends the real-time current value to the control circuit; the control circuit 40 can compare the real-time current value with the current limiting value, and generate a cut-off signal when the real-time current value is not less than the current limiting value, and output the cut-off signal to the drive circuit; when receiving the cut-off signal, the drive circuit 10 controls the disconnection of the heating circuit of the PTC heater according to the cut-off signal. For example, the current limiting value of some components in the heating circuit is 75A. When the PTC heater is turned on, the current acquisition circuit 30 acquires the current value in the heating circuit in real time and sends the acquired current value to the control module 40 in real time. When the current value is not less than 75A, some components in the heating circuit may be damaged if they are in this state for a long time. The control module 40 can output a cut-off signal to the drive module 10 to control the heating circuit to stop heating to avoid component damage. The component can be a high-power switching tube such as an IGBT.

[0064] In this embodiment, after the heating circuit is disconnected, the real-time current value is compared with the safe current value in real time. When the real-time current value is lower than the safe current value, the control module 40 outputs a conduction signal to control the drive circuit 10 to control the conduction of the heating circuit.

[0065] In addition, the control module 40 can also compare the current value with the overcurrent value to determine that the current value is always lower than the overcurrent value to avoid directly damaging the components.

[0066] Among them, the current value refers to the current value in the heating circuit of the PTC heater acquired in real time. The current limiting value refers to the current value that may cause damage to the components. If the current value exceeds the current limiting value for a long time, there may be a risk of damage to the components in the heating circuit. The overcurrent value refers to the maximum current value that the components can withstand. The components can only work for a very short time at the corresponding overcurrent value, and the current value in the components cannot exceed the overcurrent value repeatedly within a certain period of time. The components will be damaged if they only work for a very short time within the overcurrent value, and will also be directly damaged if they are in the overcurrent value multiple times in a short time. The current limiting value can be set according to the power of the components in the heating circuit.

[0067] Refer to Figure 6 , in this embodiment, the drive circuit 10 includes IGBT Q1 with the same number as the PTC heaters;

[0068] Among them, the gate of the IGBT Q1 is connected to the control circuit 40, the collector of the IGBT Q1 is connected to the output end of the corresponding PTC heater, and the emitter of the IGBT Q1 is connected to the input end of the current acquisition circuit 30.

[0069] It should be noted that in this embodiment, the driving circuit 10 controls the on-off of the heating circuit of the PTC heater by setting the IGBT Q1. Refer to Figure 7 , Figure 7 Taking two PTC heaters as an example. When multiple PTC heaters need to be driven simultaneously, the driving circuit 10 can set the corresponding number of IGBT Q1s, and use one IGBT Q1 to control the on-off of the heating circuit in one PTC heater.

[0070] In a specific implementation, the control module 40 can directly input a corresponding high-level signal or low-level signal to the gate of the IGBT Q1 to control whether the IGBT Q1 is turned on, thereby controlling whether the heating circuit of the PTC heater is turned on. For example, when the IGBT Q1 is turned on by a high level, the control module 40 can directly input a high-level conduction signal to the gate of the IGBT Q1 to control the conduction of the corresponding heating circuit; of course, the control module 40 can also directly input a low-level cut-off signal to the gate of the IGBT Q1 to control the disconnection of the corresponding heating circuit. When multiple PTC heaters are included, the control module 40 can separately output a cut-off signal or a conduction signal to control the on-off of the heating circuit of a single PTC heater, or the control module 40 can also simultaneously output multiple cut-off signals or conduction signals to control the on-off of the heating circuits of multiple PTC heaters at the same time.

[0071] In this embodiment, the switching circuit 20 includes: diodes D1 having the same number as the PTC heaters;

[0072] Among them, the positive electrode of the diode D1 is connected to the output end of the resistor in the corresponding PTC heater, and the negative electrode of the diode D1 is connected to the input end of the resistor in the corresponding PTC heater.

[0073] It should be noted that the switching circuit 20 can adopt devices with switching functions such as diodes, switching elements, and switching tubes. Refer to Figure 7 In this embodiment, the switching circuit 20 takes the diode D1 as an example.

[0074] It should be understood that when the heating circuit is disconnected, the diode D1 can form a charging circuit with the parasitic capacitor C1 and the parasitic inductance. At this time, the energy stored in the parasitic inductance L1 can charge the parasitic capacitor C1, thereby increasing the voltage value across the parasitic capacitor C1. When the heating circuit is turned on, the diode D1 is in a cut-off state due to the access of the power supply DC and will not affect the components in the heating circuit.

[0075] In this embodiment, the current acquisition circuit 30 includes: current sampling resistors R2 having the same number as the PTC heaters;

[0076] Wherein, the first end of the current sampling resistor R2 is connected to the emitter of the corresponding IGBT Q1, and the second end of the current sampling resistor R2 is connected to the negative electrode of the power supply DC.

[0077] It should be noted that when collecting the real-time current value of the heating circuit in the PTC heater, the current sampling resistor R2 can be set, and the current measuring device can directly collect the current value through the current sampling resistor R2 to obtain the real-time current value. Of course, the voltage measuring device can also obtain the voltage value across the current sampling resistor R2 and obtain the current value passing through the current sampling resistor R2 by calculation to obtain the real-time current value.

[0078] In this embodiment, the current suppression circuit further includes: a filter circuit 50; the filter circuit includes: a filter capacitor C2;

[0079] Wherein, the first end of the filter capacitor C2 is connected to the positive electrode of the power supply DC and the input end of the PTC heater, and the output end of the filter capacitor C2 is connected to the negative electrode of the power supply DC and the second end of the current sampling resistor.

[0080] It should be noted that the power supply DC provides a certain power supply voltage for the PTC heater, but the power supply voltage may fluctuate to cause the power supply voltage input to the PTC heater to be unstable, resulting in the instability of the current value in the heating circuit. In this embodiment, the filter capacitor C2 can be set at both ends of the power supply DC, and the power supply voltage provided by the power supply DC can be stabilized through the charge and discharge characteristics of the filter capacitor C2, so as to avoid the instability of the power supply voltage input to the PTC heater and the real-time current value in the heating circuit. It should be understood that the filter circuit 50 can also be composed of other components with filtering functions, which are not specifically limited here.

[0081] In this embodiment, the current suppression circuit further includes: a fuse F and a contactor K;

[0082] Wherein, the first end of the fuse F is connected to the positive electrode of the power supply DC, the second end of the fuse F is connected to the first end of the contactor K, and the second end of the contactor K is connected to the input end of the PTC heater and the first end of the filter capacitor C2.

[0083] It should be noted that the fuse F can be used to control the current in the heating circuit of the PTC heater. When the current value in the heating wheel circuit of the PTC heater is too large, the fuse will directly disconnect the input of the power voltage from the power supply DC, avoiding damage to the PTC heater. The maximum current that the fuse F can withstand is the current limiting value of the PTC. The contactor K is used to control the power voltage provided by the power supply DC to supply power to the PTC heater.

[0084] In this embodiment, a current suppression circuit is proposed. The current suppression circuit collects the real-time current value in the heating circuit of the PTC heater, and when the real-time current value is not less than the current limiting value, controls the heating circuit to turn off, and the parasitic inductance charges the parasitic capacitance. By repeatedly controlling the on and off of the heating circuit, the current in the heating circuit is suppressed.

[0085] To achieve the above object, the present invention also proposes a current suppression system, and the current suppression system includes the current suppression circuit as described above. The specific structure of this current suppression circuit refers to the above embodiment. Since this current suppression system adopts all the technical solutions of the above all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, and will not be elaborated here one by one.

[0086] Refer to Figure 8 , Figure 8 is a schematic flowchart of the first embodiment of the current suppression method of the present invention. Based on Figure 8 the first embodiment of the current suppression method of the present invention is proposed.

[0087] In this embodiment, the current suppression method includes:

[0088] Step S10: Control the on and off of the heating circuit of the PTC heater according to the pulse drive signal with the preset duty ratio;

[0089] It should be understood that the execution subject of the current suppression method of the present invention is the current suppression system. The current suppression system can output a pulse drive signal with a preset duty ratio to control the on and off of the heating circuit in the PTC heater. Within the effective duty ratio range of a cycle of the pulse drive signal with the preset duty ratio, the heating circuit of the PTC heater is in the on state, and within the invalid duty ratio range of a cycle of the pulse drive signal with the preset duty ratio, the heating circuit of the PTC heater is in the off state.

[0090] Step S20: When the heating circuit is disconnected, control the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitance, so that when the heating circuit is turned on, the voltage across the parasitic inductance is reduced, and the current in the parasitic inductance is suppressed.

[0091] It should be noted that during the conduction time of the heating circuit, a certain amount of energy is stored in the parasitic inductance. When the heating circuit is disconnected, the parasitic inductance can charge the parasitic capacitance with the stored energy. When the heating circuit is conducted again, due to the presence of a certain voltage across the parasitic capacitance, the voltage value across the parasitic inductance decreases, thereby reducing the current value in the parasitic inductance.

[0092] In this embodiment, a current suppression method is provided. The current suppression method controls the on / off of the heating circuit in the PTC heater by a pulse drive signal with a preset duty ratio received; when the heating circuit is disconnected, it controls the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitance, so that when the heating circuit is conducted, the voltage across the parasitic inductance is reduced and the current in the parasitic inductance is suppressed. In this embodiment, the on / off of the heating circuit in the PTC heater is controlled by inputting a pulse drive signal with a preset duty ratio. When the heating circuit in the PTC heater is disconnected multiple times under the control of the pulse drive signal with the preset duty ratio, the parasitic inductance in the PTC heater charges the corresponding parasitic capacitance, thereby suppressing the current in the parasitic inductance when the heating circuit is conducted.

[0093] Refer to Figure 9 , Figure 9 FIG. is a schematic flow chart of the second embodiment of the current suppression method of the present invention. Based on the first embodiment of the above current suppression method, the second embodiment of the current suppression method of the present invention is proposed.

[0094] In this embodiment, before step S20, it further includes:

[0095] Step S101: When the PTC heater is turned on, collect the real-time current value in the heating circuit of the PTC heater;

[0096] It should be noted that the current suppression system can collect the real-time current value in the PTC heating circuit through the provided current acquisition circuit when the PTC heater is turned on.

[0097] Step S102: Compare the real-time current value with the current limiting value, and generate a cut-off signal when the real-time current value is not less than the current limiting value;

[0098] It should be noted that when the real-time current value is compared with the current limiting value, when the real-time current value is greater than or equal to the current limiting value, the heating circuit is in a state of excessive current value; when the real-time current value is less than the current limiting value, the heating circuit is in a normal current value state.

[0099] Step S103: Control the heating circuit of the PTC heater to be disconnected according to the cut-off signal.

[0100] It should be understood that when the PTC heater is turned on, the current suppression system collects the real-time current value in the heating circuit of the PTC heater, compares the real-time current value with the current limiting value, and generates a cut-off signal when the real-time current value is not less than the current limiting value; controls the disconnection of the heating circuit of the PTC heater according to the cut-off signal, and the parasitic inductance can charge the parasitic capacitance with the stored energy. When the heating circuit is turned on again, since there is a certain voltage across the parasitic capacitance, the voltage value across the parasitic inductance decreases, thereby reducing the current value in the parasitic inductance.

[0101] In this embodiment, a current suppression method is provided. The current suppression method collects the real-time current value in the heating circuit of the PTC heater, and when the real-time current value is not less than the current limiting value, controls the heating circuit to turn off, and the parasitic inductance charges the parasitic capacitance. The current in the heating circuit is suppressed by controlling the on and off of the heating circuit multiple times.

[0102] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structure or equivalent process transformation made by using the content of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, shall be included in the patent protection scope of the present invention by the same token.

Claims

1. A current suppression circuit, characterized in that, The current suppression circuit includes: a drive circuit and a switch circuit; Wherein, the drive circuit is connected to the PTC heater, and the switch circuit is connected to the PTC heater; The drive circuit is configured to control the on / off of the heating circuit in the PTC heater according to a received pulse drive signal with a preset duty cycle during the startup process of the PTC heater; The switch circuit is configured to, when the heating circuit is disconnected, control the parasitic inductance in the PTC heater to charge the corresponding parasitic capacitor to increase the voltage across the parasitic capacitor, so that when the heating circuit is turned on, the voltage across the parasitic inductance is reduced to suppress the current in the parasitic inductance; When the heating circuit is disconnected, the switch circuit, the parasitic inductance, and the parasitic capacitor form a charging circuit for charging the parasitic capacitor; The current suppression circuit further includes: a current acquisition circuit and a control circuit; Wherein, the current acquisition circuit is connected to the PTC heater through the drive circuit, and the control circuit is connected to the current acquisition circuit and the drive circuit; The current acquisition circuit is configured to, when the PTC heater is turned on, acquire the real-time current value in the heating circuit of the PTC heater and send the real-time current value to the control circuit; The control circuit is configured to compare the real-time current value with a current limiting value, and generate a cut-off signal when the real-time current value is not less than the current limiting value, and output the cut-off signal to the drive circuit; The drive circuit is further configured to, when receiving the cut-off signal, control the heating circuit of the PTC heater to be disconnected according to the cut-off signal; The pulse drive signal with a preset duty cycle repeatedly controls the heating circuit to be turned on or off within the time of the pulse drive signal until the startup of the PTC heater is completed.

2. The current suppression circuit according to claim 1, wherein The drive circuit includes the same number of IGBTs as the number of PTC heaters; Wherein, the gate of the IGBT is connected to the control circuit, the collector of the IGBT is connected to the output end of the corresponding PTC heater, and the emitter of the IGBT is connected to the input end of the current acquisition circuit.

3. The current suppression circuit according to claim 2, characterized in that, The switch circuit includes: the same number of diodes as the number of PTC heaters; Wherein, the positive electrode of the diode is connected to the output end of the resistor in the corresponding PTC heater, and the negative electrode of the diode is connected to the input end of the resistor in the corresponding PTC heater.

4. The current suppression circuit according to claim 3, wherein The current acquisition circuit includes: the same number of current sampling resistors as the number of PTC heaters; Wherein, the first end of the current sampling resistor is connected to the emitter of the corresponding IGBT, and the second end of the current sampling resistor is connected to the negative pole of the power supply.

5. The current suppression circuit according to claim 4, wherein The current suppression circuit further includes: a filter circuit; the filter circuit includes: a filter capacitor; Wherein, the first end of the filter capacitor is connected to the positive pole of the power supply and the input end of the PTC heater, and the output end of the filter capacitor is connected to the negative pole of the power supply and the second end of the current sampling resistor.

6. The current suppression circuit according to claim 5, characterized in that, The current suppression circuit further includes: a fuse and a contactor; Wherein, the first end of the fuse is connected to the positive electrode of the power supply, the second end of the fuse is connected to the first end of the contactor, and the second end of the contactor is connected to the input end of the PTC heater and the first end of the filter capacitor.

7. A current suppression system, characterized in that, The current suppression system includes the current suppression circuit according to any one of claims 1-6.

8. A current suppression method for the current suppression system according to claim 7, characterized in that, The current suppression method includes: During the startup process of the PTC heater, controlling the on / off of the heating circuit of the PTC heater according to the pulse drive signal with the preset duty cycle; When the heating circuit is disconnected, controlling the parasitic inductor in the PTC heater to charge the corresponding parasitic capacitor to increase the voltage across the parasitic capacitor, so that when the heating circuit is turned on, the voltage across the parasitic inductor is reduced to suppress the current in the parasitic inductor; Before the step of controlling the parasitic inductor in the PTC heater to charge the corresponding parasitic capacitor to increase the voltage across the parasitic capacitor when the heating circuit is disconnected, so that when the heating circuit is turned on, the voltage across the parasitic inductor is reduced to suppress the current in the parasitic inductor, further includes: When the PTC heater is turned on, collecting the real-time current value in the heating circuit of the PTC heater; Comparing the real-time current value with the current limiting value, and generating a cut-off signal when the real-time current value is not less than the current limiting value; Controlling the heating circuit of the PTC heater to be disconnected according to the cut-off signal; The pulse drive signal with the preset duty cycle repeatedly controls the heating circuit to be turned on or off within the time of the pulse drive signal until the startup of the PTC heater is completed.

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