Power switching circuit suitable for direct current charger

Abstract

The utility model relates to a power switching circuit suitable for a direct current charger, which belongs to the technical field of charger power supply and comprises a relay driving circuit Q1, a relay switching module, an MOS (metal oxide semiconductor) tube driving circuit Q2, an MOS tube switching module and a processor. The first end of the relay driving circuit Q1 is connected with the processor, and the second end is connected with the first end of the relay switching module; the first end of the MOS tube driving circuit Q2 is connected with the processor, and the second end of the MOS tube driving circuit Q2 is connected with the first end of the MOS tube switching module; the second end of the relay switching module and the second end of the MOS tube switching module are respectively connected with the input end I < nput > of a power switching loop, and the third end of the relay switching module and the third end of the MOS tube switching module are respectively connected with the output end Output of the power switching loop. The scheme combines the advantages of high conduction speed, long service life of the switch and low conduction internal resistance of the relay of the S < C > MOS tube, so that the charger is safer and more stable, and the maintenance cost is reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of charger power supply, in particular to a power switching circuit suitable for a DC charger. Background Art

[0002] With the increasing popularity of electric vehicles, the demand for efficient, fast and reliable charging facilities has increased dramatically. Charging piles are needed in more and more occasions. However, due to the limitations of site and power supply, charging power needs to be allocated in a timely and reasonable manner to maximize the efficiency of site and power supply. Charger power switching circuits have emerged.

[0003] The DC charger power switching circuit is a power distribution technology used for high-power DC chargers. The current electric vehicle DC charger switching circuits include MOS tube electronic device switching, magnetic latching relay switching, and DC contactor switching to achieve DC charger power switching control. Among them, if MOS tube electronic devices are used for switching, MOS tubes have fast switching capabilities and can switch from a fully closed state to a fully open state in a very short time. However, due to the high output current during the operation of the charger, the MOS tube device is prone to severe heating of the MOS tube due to the operating voltage drop after a long working time, resulting in power loss and safety accidents. If magnetic latching relays are used for switching, magnetic latching relays can maintain the contact state unchanged after power is removed, and have high stability and reliability. However, due to the low operating voltage of magnetic latching relays and the fact that the voltage is always maintained in a DC environment, arcs are generated at the moment of contact and disconnection. Only a sufficient air gap can extinguish the arcs. Otherwise, the arcs will continue until the contacts burn out, directly damaging the magnetic latching relays. Therefore, they cannot be directly used for switching high-voltage power circuits. If DC contactors are used for switching, DC contactors can operate stably under high voltage and high current conditions. However, they also generate arcs when the circuit is disconnected, requiring the installation of additional arc suppression equipment for enhanced protection. The manufacturing process is complex, increasing the complexity and cost of the equipment.

[0004] Therefore, a power switching circuit is needed that can withstand high voltage and high current while making the connection more stable and reducing maintenance costs. Utility Model Content

[0005] The utility model provides a power switching circuit suitable for a DC charger, comprising: a relay driving circuit Q1, a relay switching module, a MOS transistor driving circuit Q2, a MOS transistor switching module, and a processor; a first end of the relay driving circuit Q1 is connected to the processor, and a second end is connected to a first end of the relay switching module; a first end of the MOS transistor driving circuit Q2 is connected to the processor, and a second end is connected to a first end of the MOS transistor switching module; a second end of the relay switching module and a second end of the MOS transistor switching module are respectively connected to an input end Input of a power switching circuit, and a third end of the relay switching module and a third end of the MOS transistor switching module are respectively connected to an output end Output of the power switching circuit.

[0006] Furthermore, the relay switching module includes: an electromagnetic relay K1, a static contact NC and a dynamic contact NO; one end of the electromagnetic relay K1 is connected to the second end of the relay drive circuit Q1, and the other end is grounded; the static contact NC is connected to the input end I nput of the power switching circuit, and the dynamic contact NO is connected to the output end Output of the power switching circuit.

[0007] Furthermore, the MOS transistor switching module includes: a MOS transistor T1 and a MOS transistor T2; a power supply electrode G1 of the MOS transistor T1 is connected to the second end of the MOS transistor driving circuit Q2, a drain electrode D1 is connected to the input end Input of the power switching circuit, and a source electrode S1 is connected to the source electrode S2 of the MOS transistor T2 and is grounded; a power supply electrode G2 of the MOS transistor T2 is connected to the second end of the MOS transistor driving circuit Q2, a source electrode S2 is grounded, and a drain electrode D2 is connected to the output end Output of the power switching circuit.

[0008] Furthermore, the MOS transistor T1 and the MOS transistor T2 are SiC MOS transistors.

[0009] Furthermore, it also includes a current transformer L1; the magnetic coil of the current transformer L1 is wrapped around the circuit of the MOS tube switching module.

[0010] Furthermore, one end of the current transformer L1 is connected to the processor, and the other end is grounded.

[0011] The beneficial effects of the present invention are as follows: This solution uses a MOS tube switching module and an electromagnetic relay switching module in parallel to form a power switching circuit. When closing the loop, the MOS tube switching module is closed first, so that the MOS tube can withstand instantaneous high voltage and large current. The MOS tube switching mode has a fast conduction speed, which increases the startup speed of the power switching circuit. Then, the electromagnetic relay switching module is closed. Since the resistance of the electromagnetic relay is much smaller than that of the MOS tube, most of the current is transmitted through the electromagnetic relay, which significantly reduces the heating of the MOS tube, reduces power loss, improves power transmission efficiency and circuit safety, and the electromagnetic relay has a low conduction internal resistance and stable connection, which reduces power loss and improves the stability of the entire circuit. When disconnecting the loop, this solution first disconnects the electromagnetic relay switching module and then disconnects the MOS tube switching module. Due to the semiconductor characteristics of the MOS tube, the possibility of the electromagnetic relay generating "arcing" is reduced, the service life of the electromagnetic relay is increased, and safety accidents caused by arcing are prevented. In addition, this solution uses SiC MOS tube components instead of ordinary MOS tubes. SiC MOS tubes have better high-voltage resistance than ordinary MOS tubes. This solution forms a power switching circuit by connecting a MOS tube switching module and an electromagnetic relay switching module in parallel. It combines the advantages of SiC MOS tubes' fast conduction and relay connections, while eliminating the disadvantages of SiC MOS tubes' prone heating when exposed to high currents and the prone arcing when relays are switched on and off. The solution has a simple and reliable structure, improves the safety and stability of the charger, and reduces maintenance costs.

[0012] These and other purposes, features and advantages of the present invention are fully reflected in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 The following is a schematic diagram showing the circuit structure of a power switching circuit suitable for a DC charger of the present invention;

[0014] Figure 2 The following is a schematic diagram showing a circuit closing process of a power switching circuit suitable for a DC charger according to the present invention;

[0015] Figure 3 The utility model shows a circuit disconnection process diagram of a power switching circuit suitable for a DC charger.

[0016] Reference numerals: 1-relay switching module, 2-MOS tube switching module, 3-processor. DETAILED DESCRIPTION

[0017] The following description is intended to disclose the present invention and enable those skilled in the art to implement the present invention. The preferred embodiments described below are provided for illustrative purposes only, and those skilled in the art will readily appreciate other obvious variations. The basic principles of the present invention as defined in the following description may be applied to other embodiments, variations, improvements, equivalents, and other technical solutions that do not depart from the spirit and scope of the present invention.

[0018] Those skilled in the art should understand that, in the disclosure of the specification, the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the above terms cannot be understood as limiting the present invention.

[0019] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the elements may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0020] refer to Figures 1 to 3 A power switching circuit suitable for a DC charger according to a preferred embodiment of the present invention will be described in detail below.

[0021] Figure 1 This is a schematic diagram of the circuit structure of a power switching circuit suitable for a DC charger in the present invention. Figure 1 As shown, the program includes:

[0022] A relay drive circuit Q1, a relay switching module 1, a MOS transistor drive circuit Q2, a MOS transistor switching module 2, and a processor 3; a first end of the relay drive circuit Q1 is connected to the processor 3, and a second end is connected to the first end of the relay switching module 1; a first end of the MOS transistor drive circuit Q2 is connected to the processor 3, and a second end is connected to the first end of the MOS transistor switching module 2; a second end of the relay switching module 1 and a second end of the MOS transistor switching module 2 are respectively connected to an input end of a power switching circuit, Input, and a third end of the relay switching module 1 and a third end of the MOS transistor switching module 2 are respectively connected to an output end of a power switching circuit, Output.

[0023] Specifically, the relay switching module 1 includes: an electromagnetic relay K1, a static contact NC and a dynamic contact NO; one end of the electromagnetic relay K1 is connected to the second end of the relay drive circuit Q1, and the other end is grounded; the static contact NC is connected to the input end I nput of the power switching circuit, and the dynamic contact NO is connected to the output end Output of the power switching circuit.

[0024] Specifically, the MOS transistor switching module 2 includes: a MOS transistor T1 and a MOS transistor T2; a power supply electrode G1 of the MOS transistor T1 is connected to the second end of the MOS transistor drive circuit Q2, a drain electrode D1 is connected to the input end Input of the power switching circuit, and a source electrode S1 is connected to the source electrode S2 of the MOS transistor T2 and is grounded; a power supply electrode G2 of the MOS transistor T2 is connected to the second end of the MOS transistor drive circuit Q2, a source electrode S2 is grounded, and a drain electrode D2 is connected to the output end Output of the power switching circuit.

[0025] Specifically, the MOS transistor T1 and the MOS transistor T2 are SiC MOS transistors.

[0026] In one embodiment, when the power switching circuit is about to execute a closing command, processor 3 first sends a control signal to MOS transistor driver circuit Q2, which, through MOS transistor driver circuit Q2, closes MOS transistors T1 and T2 in MOS transistor switching module 2, rapidly starting the power switching circuit and carrying load, turning on the branch circuit containing MOS transistor switching module 2. Processor 3 then sends a control signal to relay driver circuit Q1, which outputs a positive pulse signal, causing electromagnetic relay K1 in relay switching module 1 to form an electromagnetic coil, causing dynamic contact NO to overcome the spring force and contact static contact NC, closing and energizing the branch circuit containing relay switching module 1. At this point, due to the low on-resistance characteristics of the relay, the voltage in the branch circuit containing relay switching module 1 is much lower than the voltage in the branch circuit containing MOS switching module 2. The branch circuit containing relay switching module 1 carries the majority of the transmission current, reducing the voltage drop across the SiC MOS transistor and minimizing severe heating and energy loss in the SiC MOS transistor.

[0027] In one embodiment, when the power switching circuit is about to execute a disconnect command, processor 3 first sends a control signal to relay driver circuit Q1. Relay driver circuit Q1 outputs a negative pulse signal, deactivating the electromagnetic coil of electromagnetic relay K1 in relay switching module 1. Dynamic contact NO is pulled away by spring force, disconnecting it from static contact NC, and disconnecting the branch circuit where relay switching module 1 resides. Processor 3 then sends a control signal to MOS transistor driver circuit Q2, which, through MOS transistor driver circuit Q2, disconnects MOS transistors T1 and T2 in MOS transistor switching module 2, de-energizing the branch circuit where MOS transistor switching module 2 resides and quickly disconnecting the power switching circuit. At this point, because the SiC MOS transistor de-energizes later than the electromagnetic relay, the semiconductor properties of the SiC MOS transistor reduce the likelihood of arcing in the electromagnetic relay, preventing arcing from persisting and potentially burning the contacts. This effectively increases the service life of the electromagnetic relay, prevents safety incidents, and ensures the safety and efficiency of the charger.

[0028] Preferably, it further comprises a current transformer L1 ; the magnetic coil of the current transformer L1 is wrapped around the circuit of the MOS tube switching module 2 .

[0029] Specifically, one end of the current transformer L1 is connected to the processor 3 , and the other end is grounded.

[0030] In one embodiment, current transformer L1 wraps a magnetic coil around the circuit of MOS transistor switching module 2. This electromagnetic induction effect monitors the operating current value of the branch circuit where MOS transistor switching module 2 is located in real time and transmits this operating current value to processor 3. When the operating current value exceeds a preset current value and the duration exceeds a preset time threshold, processor 3 issues an alarm signal to personnel and executes a disconnect sequence. Through real-time monitoring of the circuit by current transformer L1, overcurrent protection is implemented for MOS transistor switching module 2.

[0031] It should be noted that the terms "first" and "second" in the present invention are only used for descriptive purposes and do not indicate any order. They cannot be understood as indicating or implying relative importance. These terms can be interpreted as names.

[0032] Those skilled in the art will appreciate that the embodiments of the present invention described above and shown in the accompanying drawings are provided for illustrative purposes only and do not limit the present invention. The advantages of the present invention have been fully and effectively realized. The functional and structural principles of the present invention have been demonstrated and illustrated in the embodiments. Any variations or modifications may be made to the embodiments of the present invention without departing from the principles described.

Claims

1. A power switching circuit suitable for a DC charger, characterized in that: include: Relay drive circuit Q1, relay switching module (1), MOS tube drive circuit Q2, MOS tube switching module (2) and processor (3); The first end of the relay drive circuit Q1 is connected to the processor (3), and the second end is connected to the first end of the relay switching module (1); the first end of the MOS tube drive circuit Q2 is connected to the processor (3), and the second end is connected to the first end of the MOS tube switching module (2); The second end of the relay switching module (1) and the second end of the MOS tube switching module (2) are respectively connected to the power switching circuit input end Input, and the third end of the relay switching module (1) and the third end of the MOS tube switching module (2) are respectively connected to the power switching circuit output end Output.

2. A power switching circuit suitable for a DC charger according to claim 1, characterized in that: The relay switching module (1) comprises: an electromagnetic relay K1, a static contact NC and a dynamic contact NO; One end of the electromagnetic relay K1 is connected to the second end of the relay drive circuit Q1, and the other end is grounded; the static contact NC is connected to the input end Input of the power switching circuit, and the dynamic contact NO is connected to the output end Output of the power switching circuit.

3. A power switching circuit suitable for a DC charger according to claim 1, characterized in that: The MOS transistor switching module (2) comprises: a MOS transistor T1 and a MOS transistor T2; Among them, the power supply electrode G1 of the MOS transistor T1 is connected to the second end of the MOS transistor drive circuit Q2, the drain electrode D1 is connected to the input end Input of the power switching circuit, and the source electrode S1 is connected to the source electrode S2 of the MOS transistor T2 and grounded; the power supply electrode G2 of the MOS transistor T2 is connected to the second end of the MOS transistor drive circuit Q2, the source electrode S2 is grounded, and the drain electrode D2 is connected to the output end Output of the power switching circuit.

4. A power switching circuit suitable for a DC charger as claimed in claim 3, characterized in that: The MOS transistor T1 and the MOS transistor T2 are SiC MOS transistors.

5. A power switching circuit suitable for a DC charger according to claim 1, characterized in that: Also includes a current transformer L1; The magnetic coil of the current transformer L1 is wrapped around the circuit of the MOS tube switching module (2).

6. A power switching circuit suitable for a DC charger as claimed in claim 5, characterized in that: One end of the current transformer L1 is connected to the processor (3), and the other end is grounded.

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