Three-phase balancing and power adjusting circuit design for three-phase alternating current charging pile

Abstract

A three-phase balancing and power adjusting circuit design for a three-phase alternating-current charging pile, relating to the field of electric vehicle charging. The three-phase balancing and power adjusting circuit design comprises an IT grounding system, a TN grounding system, a power adjusting function relay and a main relay. The IT grounding system is provided with input line ports L1, L2 and L3, and the TN grounding system is provided with input line ports N, L1, L2, L3 and PE. The power adjusting function relay only performs no-load switching, so that the performance requirement of the relay is lower than that of the main relay, and the cost of the relay can be greatly reduced. The main relay is used in a scenario in which load switching is performed, so that the performance requirement of the main relay is relatively high. According to relevant standards, it is required that the contact gap of the main relay be greater than or equal to 3.0 mm, and the electrical life needs to meet a service life requirement of fifty thousand operations for a rated current carrying switch.

Description

Design of a three-phase balanced power distribution circuit for a three-phase AC charging pile Technical Field

[0001] The present invention relates to the field of electric vehicle charging, and in particular to a three-phase balanced power allocation circuit design for a three-phase AC charging pile. Background Art

[0002] The electric vehicle industry is developing rapidly. As the number of users purchasing electric vehicles increases, public charging station resources are in short supply. More and more users will install charging piles at home. The AC charging piles that are commonly used by households are mostly single-phase AC charging piles. Some households will also purchase three-phase AC charging piles. Conventional three-phase AC charging piles do not have three-phase balanced power allocation function.

[0003] Currently, the most commonly used electric vehicle charging piles are single-phase AC charging piles. Single-phase AC charging piles are fixedly connected to one of the three-phase power phases when the charging pile is first installed. Conventional three-phase AC piles, although they are connected to three-phase power at the time of installation, do not have three-phase balancing and power allocation circuits inside, especially in single-phase charging mode. They actually still use a single phase of power that cannot be switched freely. The above charging methods will lead to three-phase imbalance problems, and the single-phase charging method will bring a heavy burden to the three-phase AC power grid. Summary of the Invention

[0004] The purpose of the present invention is to provide a three-phase balanced power allocation circuit design for a three-phase AC charging pile in order to achieve the purpose of using this double-contact type main relay as the switch of the main circuit, being compatible with both three-phase charging application scenarios and single-phase charging application scenarios. When only K1 is closed, it works in single-phase charging mode, and when K1 and K2 are closed at the same time, it can work in three-phase charging mode.

[0005] To achieve the above objectives, the present invention provides the following technical solutions: a three-phase balanced power allocation circuit design for a three-phase AC charging pile, wherein the three-phase balanced power allocation circuit design includes an IT grounding system, a TN grounding system, a power allocation function relay and a main relay.

[0006] Preferably, the IT grounding system is provided with incoming line ports L1, L2, and L3, and the TN grounding system is provided with incoming line ports N, L1, L2, L3, and PE.

[0007] Preferably, the power allocation function relay is provided with K4, K5, K6, K7, and K8, and the main relay is provided with K1 and K2. The power allocation function relay adopts a single-circuit contact type relay, and the main relay adopts a double-circuit contact type relay.

[0008] Preferably, the input and output contacts of the power allocation function relay K4 are respectively connected to the input contacts of the incoming line port L1 and the two main contacts of the main relay K1, and the output contacts of K4 are also connected to the output contacts of the power allocation function relays K5 and K6.

[0009] Preferably, the input contacts and output contacts of the power allocation function relay K5 are respectively connected to the input contacts of the incoming line port L2 and the two main contacts of the main relay K1, and the output contacts of K5 are also connected to the output contacts of the power allocation function relays K4 and K6.

[0010] Preferably, the input contacts and output contacts of the power allocation function relay K6 are respectively connected to the input contacts of the incoming line port L3 and the two main contacts of the main relay K1, and the output contacts of K6 are also simultaneously connected to the output contacts of the power allocation function relays K4 and K5.

[0011] Preferably, the input contact and output contact of the power allocation function relay K7 are respectively connected to the input contact of the incoming line port L1 and the input contact of the main contact 1 of the main relay K1, and the output contact of K7 is also connected to the output contact of the power allocation function relay K8.

[0012] Preferably, the input contacts and output contacts of the power allocation function relay K8 are respectively connected to the input contacts of the incoming port N and the main contact 1 of the main relay K1, and the output contacts of K8 are also connected to the output contacts of the power allocation function relay K7.

[0013] Preferably, the following application scenarios are included:

[0014] Scenario 1: In a TN grounding system, as shown in Figure 2, closing K4, K8, K1, and K2 simultaneously can achieve normal three-phase charging function. When the system detects that three-phase imbalance requires power allocation, it first disconnects all relays K4, K8, K1, and K2. The system determines the current power allocation to L1, L2, or L3 based on a certain algorithm according to the current three-phase imbalance and continues to charge the electric vehicle in a single-phase charging mode. For example, if the load on L1 of the current system is light, the system will first close K4 and K8 to detect the status of the power allocation function relay. When all are in the correct state, K1 is closed alone, and single-phase charging of the electric vehicle is realized through L1; for example, if the load of L2 of the current system is relatively light, the system will first close K5 and K8. When it is detected that the states of the power allocation function relays are all in the correct state, K1 is closed alone, and single-phase charging of the electric vehicle is realized through L2; for example, if the load of L3 of the current system is relatively light, the system will first close K6 and K8. When it is detected that the states of the power allocation function relays are all in the correct state, K1 is closed alone, and single-phase charging of the electric vehicle is realized through L3.

[0015] Scenario 2: In an IT grounding system, as shown in Figure 3, closing K4, K8, K1, and K2 simultaneously can achieve normal three-phase charging function. When the system detects that three-phase imbalance requires power allocation, it first disconnects all relays K4, K8, K1, and K2. The system determines the current power allocation to L1 and L2, or L2 and L3, or L3 and L1 based on a certain algorithm according to the current three-phase imbalance and continues to charge the electric vehicle in a single-phase charging mode. For example, if the load on L1 and L2 of the current system is light, the system will first close K4 and K8 and detect that the status of the power allocation function relays are all When it is already in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L1 and L2; for example, if the load of L2 and L3 of the current system is relatively light, the system will first close K5 and K7. When it detects that the states of the power allocation function relays are already in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L2 and L3; for example, if the load of L3 and L1 of the current system is relatively light, the system will first close K6 and K7. When it detects that the states of the power allocation function relays are already in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L3 and L1.

[0016] Compared with the prior art, the present invention is provided with a power allocation function relay and a main relay. The power allocation function relay of the power allocation function relay only performs the off-load switching function, so the performance requirements of the relay are lower than those of the main relay; the cost of the relay can be greatly reduced, and the main relay will be used in the scenario of load switching, so the performance requirements of the main relay are relatively high. According to relevant standards, the contact gap of the main relay is required to be greater than or equal to 3.0mm, and the electrical life needs to meet the life requirement of 50,000 times of rated current load switching, etc.; and the two main relays in the present invention preferably adopt a dual-circuit contact type, which can simplify the complexity and cost of circuit design. It is precisely because of the use of this dual-contact type of main relay as the switch of the main circuit that it can be compatible with three-phase charging application scenarios and single-phase charging application scenarios at the same time. When only K1 is closed, it works in single-phase charging mode, and when K1 and K2 are closed at the same time, it can work in three-phase charging mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a schematic diagram of a system of the present invention;

[0018] FIG2 is a table showing the three-phase and single-phase power allocation states of a TN grounding system according to the present invention;

[0019] FIG3 is a table showing the three-phase and single-phase power allocation states of the IT grounding system of the present invention. DETAILED DESCRIPTION

[0020] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0021] In order to achieve the above objectives, the present invention provides a three-phase balanced power allocation circuit design for a three-phase AC charging pile, wherein the three-phase balanced power allocation circuit design includes an IT grounding system, a TN grounding system, a power allocation function relay and a main relay.

[0022] The IT grounding system is provided with incoming line ports L1, L2, and L3, and the TN grounding system is provided with incoming line ports N, L1, L2, L3, and PE.

[0023] The power allocation function relay is provided with K4, K5, K6, K7, and K8, and the main relay is provided with K1 and K2. The power allocation function relay adopts a single-circuit contact type relay, and the main relay adopts a double-circuit contact type relay.

[0024] The power supply circuit includes a voltage conversion chip U5, capacitors C1, C2, C19, C18, C21, C22, and a diode D1. Capacitors C1 and C2 are input filter capacitors of the voltage conversion chip U5, capacitors C19, C18, C21, and C22 are output filter capacitors of the voltage conversion chip U5, and diode D1 is used to prevent capacitors C1 and C2 from supplying power to the outside, thereby improving the reliability of the power supply circuit.

[0025] The input contacts and output contacts of the power allocation function relay K5 are respectively connected to the input contacts of the incoming line port L2 and the two main contacts of the main relay K1, and the output contacts of K5 are also connected to the output contacts of the power allocation function relays K4 and K6.

[0026] The input contacts and output contacts of the power allocation function relay K6 are respectively connected to the input contacts of the incoming line port L3 and the two main contacts of the main relay K1, and the output contacts of K6 are also connected to the output contacts of the power allocation function relays K4 and K5.

[0027] The input contact and output contact of the power allocation function relay K7 are respectively connected to the input contact of the incoming line port L1 and the input contact of the main contact 1 of the main relay K1, and the output contact of K7 is also connected to the output contact of the power allocation function relay K8.

[0028] The input contact and output contact of the power allocation function relay K8 are respectively connected to the input contact of the incoming line port N and the input contact of the main contact 1 of the main relay K1, and the output contact of K8 is also connected to the output contact of the power allocation function relay K7.

[0029] Scenario 1: In a TN grounding system, as shown in Figure 2, closing K4, K8, K1, and K2 simultaneously can achieve normal three-phase charging function. When the system detects that three-phase imbalance requires power allocation, it first disconnects all relays K4, K8, K1, and K2. The system determines the current power allocation to L1, L2, or L3 based on a certain algorithm according to the current three-phase imbalance and continues to charge the electric vehicle in a single-phase charging mode. For example, if the load on L1 of the current system is light, the system will first close K4 and K8 to detect the status of the power allocation function relay. When all are in the correct state, K1 is closed alone, and single-phase charging of the electric vehicle is realized through L1; for example, if the load of L2 of the current system is relatively light, the system will first close K5 and K8. When it is detected that the states of the power allocation function relays are all in the correct state, K1 is closed alone, and single-phase charging of the electric vehicle is realized through L2; for example, if the load of L3 of the current system is relatively light, the system will first close K6 and K8. When it is detected that the states of the power allocation function relays are all in the correct state, K1 is closed alone, and single-phase charging of the electric vehicle is realized through L3.

[0030] Scenario 2: In an IT grounding system, as shown in Figure 3, closing K4, K8, K1, and K2 simultaneously can achieve normal three-phase charging function. When the system detects that three-phase imbalance requires power allocation, it first disconnects all relays K4, K8, K1, and K2. The system determines the current power allocation to L1 and L2, or L2 and L3, or L3 and L1 based on a certain algorithm according to the current three-phase imbalance and continues to charge the electric vehicle in a single-phase charging mode. For example, if the load on L1 and L2 of the current system is light, the system will first close K4 and K8 and detect that the status of the power allocation function relays are all When it is already in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L1 and L2; for example, if the load of L2 and L3 of the current system is relatively light, the system will first close K5 and K7. When it detects that the states of the power allocation function relays are already in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L2 and L3; for example, if the load of L3 and L1 of the current system is relatively light, the system will first close K6 and K7. When it detects that the states of the power allocation function relays are already in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L3 and L1.

[0031] The power allocation function relay in the present invention only performs off-load switching function, so the performance requirements for the relay are lower than those for the main relay; the cost of the relay can be greatly reduced, and the main relay will be used in load switching scenarios, so the performance requirements of the main relay are relatively high. According to relevant standards, the contact gap of the main relay is required to be greater than or equal to 3.0mm, and the electrical life needs to meet the life requirement of 50,000 times of rated current load switching, etc.; and the two main relays in the present invention preferably adopt a dual-circuit contact type, which can simplify the complexity and cost of circuit design. It is precisely because of the use of this dual-contact type of main relay as the switch of the main circuit that it can be compatible with three-phase charging application scenarios and single-phase charging application scenarios at the same time. When only K1 is closed, it works in single-phase charging mode. When K1 and K2 are closed at the same time, it can work in three-phase charging mode.

[0032] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A three-phase balanced power allocation circuit design for a three-phase AC charging pile, characterized by: The three-phase balanced power allocation circuit design includes an IT grounding system, a TN grounding system, a power allocation function relay and a main relay.

2. According to claim 1, a three-phase balanced power allocation circuit design of a three-phase AC charging pile is characterized in that: The IT grounding system is provided with incoming line ports L1, L2, and L3, and the TN grounding system is provided with incoming line ports N, L1, L2, L3, and PE.

3. According to claim 1, a three-phase balanced power allocation circuit design of a three-phase AC charging pile is characterized in that: The power allocation function relay is provided with K4, K5, K6, K7, K8, and the main relay is provided with K1, K2. The power allocation function relay adopts a single-way contact type relay, and the main relay adopts a double-way contact type relay.

4. The three-phase balanced power allocation circuit design of a three-phase AC charging pile according to claim 1 is characterized in that: The input and output contacts of the power regulation function relay K4 are respectively connected to the input contacts of the incoming line port L1 and the 2 main contacts of the main relay K1, and the output contacts of K4 are also connected to the output contacts of the power regulation function relays K5 and K6.

5. The three-phase balanced power allocation circuit design of a three-phase AC charging pile according to claim 1 is characterized in that: The input contacts and output contacts of the power regulation function relay K5 are respectively connected to the input contacts of the incoming line port L2 and the 2 main contacts of the main relay K1, and the output contacts of K5 are also connected to the output contacts of the power regulation function relays K4 and K6.

6. The three-phase balanced power allocation circuit design of a three-phase AC charging pile according to claim 1 is characterized in that: The input contacts and output contacts of the power regulation function relay K6 are respectively connected to the input contacts of the incoming line port L3 and the two main contacts of the main relay K1, and the output contacts of K6 are also simultaneously connected to the output contacts of the power regulation function relays K4 and K5.

7. The three-phase balanced power allocation circuit design of a three-phase AC charging pile according to claim 1 is characterized in that: The input contact and output contact of the power regulation function relay K7 are respectively connected to the input contact of the incoming line port L1 and the input contact of the main contact 1 of the main relay K1, and the output contact of K7 is also connected to the output contact of the power regulation function relay K8.

8. The three-phase balanced power allocation circuit design of a three-phase AC charging pile according to claim 1 is characterized in that: The input contact and output contact of the power regulation function relay K8 are respectively connected to the input contact of the incoming line port N and the 1st main contact of the main relay K1, and the output contact of K8 is also connected to the output contact of the power regulation function relay K7.

9. The three-phase balanced power allocation circuit design of a three-phase AC charging pile according to claim 1 is characterized in that: The application scenarios include: Scenario 1: In a TN grounding system, as shown in Figure 2, closing K4, K8, K1, and K2 at the same time can realize the normal three-phase charging function. When the system detects that the three-phase imbalance requires power allocation, all relays K4, K8, K1, and K2 are disconnected first. The system determines the current power allocation to L1, L2, or L3 based on a certain algorithm according to the current three-phase imbalance and continues to charge the electric vehicle in a single-phase charging mode. For example, if the load of L1 in the current system is light, the system will close K4 and K8 first and detect the status of the power allocation function relay. When all are in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L1; for example, if the load of L2 of the current system is relatively light, the system will first close K5 and K8, and when it is detected that the states of the power allocation function relays are all in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L2; for example, if the load of L3 of the current system is relatively light, the system will first close K6 and K8, and when it is detected that the states of the power allocation function relays are all in the correct state, K1 is closed alone, that is, single-phase charging of the electric vehicle is realized through L3; Scenario 2: In an IT grounding system, as shown in Figure 3, closing K4, K8, K1, and K2 at the same time can realize the normal three-phase charging function. When the system detects that the three-phase imbalance requires power allocation, all relays K4, K8, K1, and K2 are disconnected first. The system determines the current power allocation to L1 and L2, or L2 and L3, or L3 and L1 based on a certain algorithm according to the current three-phase imbalance and continues to charge the electric vehicle in a single-phase charging mode. For example, if the load of L1 and L2 in the current system is light, the system will close K4 and K8 first, and detect that the states of the power allocation function relays are all When they are already in the correct state, K1 is closed alone, which enables single-phase charging of the electric vehicle through L1 and L2; for example, if the loads of L2 and L3 of the current system are relatively light, the system will first close K5 and K7. When it is detected that the states of the power allocation function relays are already in the correct state, K1 is closed alone, which enables single-phase charging of the electric vehicle through L2 and L3; for example, if the loads of L3 and L1 of the current system are relatively light, the system will first close K6 and K7. When it is detected that the states of the power allocation function relays are already in the correct state, K1 is closed alone, which enables single-phase charging of the electric vehicle through L3 and L1.

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