A dual-relay controlled charging and discharging circuit and control method

Abstract

The present invention discloses a dual-relay controlled charging and discharging circuit and control method, including: a battery charging and discharging main circuit and a relay detection control component, wherein the battery charging and discharging main circuit is composed of a battery pack and a current collector RL, a fuse RF, a power relay K1, a power relay K2, a circuit breaker QF and an inverter PCS connected in the circuit, and the relay detection control component includes a cross-type isolation acquisition circuit, a data processing unit, a control unit and an MCU. The present invention can effectively monitor the poor contact or adhesion of the relay contacts due to metal oxidation, avoid the system protection from being out of control after the adhesion of a single relay contact, make full use of the application of the relay directionality, give play to the arc extinguishing ability of the relay, effectively protect the service life of the relay, and make the entire system safer and more reliable.

Description

Technical Field

[0001] The present invention relates to the technical field of charging and discharging circuits, and in particular to a dual-relay controlled charging and discharging circuit and a control method. Background Art

[0002] The energy storage battery management system has different performance of the system battery pack due to the inconsistency of voltage, temperature and SOC between batteries, and even reaches the upper and lower limits of the alarm protection, resulting in faults and relay action. In actual applications, due to the performance differences of single cells or battery packs, there are often high-voltage and high-current circuits in the process of relay action. The instantaneous contact of the relay closing / releasing will cause metal migration and oxidation, resulting in poor contact or adhesion. This is bound to bring serious consequences to the system and may even burn the entire system. In addition to paying attention to the arc extinguishing device of the device in the selection, practical and effective control measures should be taken in the system. In the energy storage battery management system, the relay is a controllable high-voltage and high-current component. It is connected in series in the main circuit with a single relay. Its simple structure and easy control have been widely used. However, the traditional relay connection and control methods have the following shortcomings in practical applications: the metal contacts are easily oxidized at the moment of relay closure / release, resulting in poor contact or bonding; if a single relay contact sticks, the system protection will be out of control; high-power relay contacts are directional and cannot meet the system's bidirectional charging and discharging requirements; dual relays can be connected in reverse parallel to achieve charging and discharging, but once a contact oxidizes or sticks, the system will be out of control, which is risky and has low reliability. Summary of the invention

[0003] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a dual-relay controlled charging and discharging circuit and a control method.

[0004] In order to achieve the above-mentioned object, the present invention adopts the following technical scheme: a dual-relay controlled charging and discharging circuit, comprising: a battery charging and discharging main circuit and a relay detection control component;

[0005] The battery charging and discharging main circuit is composed of a battery pack and a current collector RL, a fuse RF, a power relay K1, a power relay K2, a circuit breaker QF and an inverter PCS connected in the circuit;

[0006] The relay detection control component includes a cross-type isolation acquisition circuit, a data processing unit, a control unit and an MCU, and the output ends of the cross-type isolation acquisition circuit and the MCU are connected to the data processing unit, and the output end of the data processing unit is connected to the control unit by wires, and the output end of the control unit is electrically connected to the input ends of the power relays K1 and K2.

[0007] As a further description of the above technical solution:

[0008] The power relay K1 and the power relay K2 are both polarized relays, and the inverter PCS is a bidirectional inverter for energy storage.

[0009] As a further description of the above technical solution:

[0010] The cross-type isolation acquisition circuit is used to acquire the status of the power relay K1 and the power relay K2 in real time, and the cross-type isolation acquisition circuit is also used to transmit the acquired status information to the MCU.

[0011] As a further description of the above technical solution:

[0012] The MCU is used to analyze and process the status information of the relay and issue control commands in real time according to system requirements;

[0013] The MCU adopts an external power supply mode to improve the efficiency of the control circuit itself and the voltage constraint of the control chip power supply, making the application more flexible, reducing interference, and increasing the reliability of the control circuit.

[0014] As a further description of the above technical solution:

[0015] The data processing unit is used to receive the control command issued by the MCU, process the control command and then transmit it to the control unit;

[0016] The control unit is used to receive the control signal transmitted by the data processing unit and control the opening and closing of the power relay K1 and the power relay K2.

[0017] A control method for a dual-relay controlled charging and discharging circuit comprises a relay detection method and a charging and discharging circuit control method.

[0018] As a further description of the above technical solution:

[0019] The relay detection method comprises the following steps:

[0020] SS1: When entering the main circuit relay detection normally, the power relay K1, power relay K2 and circuit breaker QF are all in the closed state;

[0021] SS2: The inverter is in shutdown or standby state. The system disconnects the power relay K1 and closes the power relay K2 according to the detection procedure, detects the Uad voltage, and determines whether the power relay K1 is bonded;

[0022] SS3: Disconnect the power relay K2, close the power relay K1, detect the Ubc voltage, determine whether the power relay K2 is bonded, and upload the detection data to the MCU for analysis and processing in real time.

[0023] As a further description of the above technical solution:

[0024] The charging and discharging circuit control method comprises the following steps:

[0025] SS1: The main circuit is in the charging state. When forced disconnection is required, the power relay K2 must be disconnected first according to the system definition, and the system stops working. The power relay K2 disconnection signal is detected through the cross-type isolation acquisition circuit, and the contact performance of the current power relay K2 after the action is detected to be normal;

[0026] SS2: The main circuit is in the discharge state. When forced disconnection is required, the power relay K1 must be disconnected first according to the system definition, and the system stops working. The power relay K1 disconnection signal is detected through the cross-type isolation acquisition circuit, and the contact performance of the current power relay K1 after the action is detected to be normal;

[0027] SS3: Main circuit closing process: According to system requirements, the power relay K1 and the power relay K2 must be closed normally, and the contacts of the power relay K1 and the power relay K2 must be normal after system detection, then the system can operate normally and enter the next step of charging and discharging process.

[0028] As a further description of the above technical solution:

[0029] In the charging and discharging circuit control method, the system detects whether the contact performance of the power relay K1 and the power relay K2 is normal, including the following steps:

[0030] S1: abnormal charging control and detection:

[0031] When the system is working normally at time t1, the power relay K1 and the power relay K2 are in the closed state, and the inverter PCS is working normally;

[0032] At time t2, due to the system alarm protection, the power relay K2 is disconnected, the power relay K1 is closed normally, and the inverter PCS is in standby or shutdown. During this period, the detection circuit automatically tests the contact status of the power relay K2. The detection result is processed by the data unit and uploaded to the MCU for analysis and processing. If the power relay K2 is normal, it is closed. If the power relay K2 is abnormal, it remains disconnected and is replaced manually.

[0033] At t3, the power relay K2 is detected to be normal and closed, and the inverter PCS can be started to work normally after a delay according to the system requirements;

[0034] S2: Abnormal discharge control and detection:

[0035] When the system is working normally at time t1, power relay K1 and power relay K2 are in a closed state, and the PCS is working normally.

[0036] At time t2, due to the system alarm protection, the power relay K1 is disconnected, the power relay K2 is closed normally, and the PCS is in standby or shut down.

[0037] During this period, the detection circuit automatically tests the contact status of the power relay K1. The detection results are processed by the data unit and uploaded to the MCU for analysis and processing. If the power relay K1 is normal, it is closed. If K1 is abnormal, it remains disconnected and is replaced manually;

[0038] At t3, it is detected that the power relay K1 is normal and closed, and the PCS can be started to work normally after a delay according to the system requirements.

[0039] Beneficial Effects

[0040] The present invention provides a dual-relay controlled charging and discharging circuit and control method, which has the following beneficial effects:

[0041] The charging and discharging circuit controlled by the dual relays can effectively monitor the poor contact or adhesion of the relay contacts due to metal oxidation, avoid the system protection loss of control after the single relay contact is adhered, make full use of the directional application of the relay, give play to the arc extinguishing ability of the relay, effectively protect the service life of the relay, and make the whole system safer and more reliable. The control method of the charging and discharging circuit controlled by the dual relays manages and controls the relays in terms of timing, broadens the application scope of polar relays, improves the speed of system control response, saves product costs, and improves the arc extinguishing ability of the relay, truly realizing the application of the invention in the actual system, and the whole system has achieved real value in terms of safety, reliability, and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 A system structure block diagram of a dual-relay controlled charging and discharging circuit and a control method proposed by the present invention;

[0043] Figure 2 It is the relay logic diagram of the present invention;

[0044] Figure 3 This is the relay logic timing diagram in the present invention. DETAILED DESCRIPTION

[0045] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0046] like Figure 1-3 As shown, a dual-relay controlled charging and discharging circuit includes: a battery charging and discharging main circuit and a relay detection control component;

[0047] The main battery charging and discharging circuit consists of a battery pack and a current collector RL, a fuse RF, a power relay K1, a power relay K2, a circuit breaker QF and an inverter PCS connected in the circuit;

[0048] During the charging and discharging process of the battery pack, there is a bidirectional current in the actual circuit work, namely the charging circuit and the discharging circuit. The positive and negative power lines in the main circuit are respectively connected to the power relay K1 and the power relay K2. Due to the performance difference of the relay parameters, the power relay K1 and the power relay K2 themselves will not be opened or closed at the same time, which effectively avoids the impact stress of large current and voltage in the main circuit;

[0049] The relay detection control component includes a cross-type isolation acquisition circuit, a data processing unit, a control unit and an MCU, and the output ends of the cross-type isolation acquisition circuit and the MCU are connected to the data processing unit, and the output end of the data processing unit is connected to the control unit by wires, and the output end of the control unit is electrically connected to the input ends of the power relays K1 and K2.

[0050] Power relay K1 and power relay K2 are both polar relays with good arc extinguishing performance and fast opening and closing speeds, etc., which can realize fast response control of this circuit and achieve system safety and reliability. Inverter PCS is a bidirectional inverter for energy storage.

[0051] The cross-type isolation acquisition circuit is used to acquire the status of the power relay K1 and the power relay K2 in real time, and the cross-type isolation acquisition circuit is also used to transmit the acquired status information to the MCU.

[0052] MCU is used to analyze and process the status information of the relay and issue control commands in real time according to system requirements;

[0053] The MCU adopts an external power supply mode to improve the efficiency of the control circuit itself and the voltage constraint of the control chip power supply, making the application more flexible, reducing interference, and increasing the reliability of the control circuit.

[0054] The data processing unit is used to receive the control commands issued by the MCU, process the control commands and then transmit them to the control unit;

[0055] The control unit is used to receive the control signal transmitted by the data processing unit and control the opening and closing of the power relay K1 and the power relay K2.

[0056] A control method for a dual-relay controlled charging and discharging circuit comprises a relay detection method and a charging and discharging circuit control method.

[0057] The relay detection method comprises the following steps:

[0058] SS1: When entering the main circuit relay detection normally, the power relay K1, power relay K2 and circuit breaker QF are all in the closed state;

[0059] SS2: The inverter is in shutdown or standby state. The system disconnects the power relay K1 and closes the power relay K2 according to the detection procedure, detects the Uad voltage, and determines whether the power relay K1 is bonded;

[0060] SS3: Disconnect the power relay K2, close the power relay K1, detect the Ubc voltage, determine whether the power relay K2 is bonded, and upload the detection data to the MCU for analysis and processing in real time.

[0061] The charging and discharging circuit control method comprises the following steps:

[0062] SS1: The main circuit is in the charging state. When forced disconnection is required, the power relay K2 must be disconnected first according to the system definition, and the system stops working. The power relay K2 disconnection signal is detected through the cross-type isolation acquisition circuit, and the contact performance of the current power relay K2 after the action is detected to be normal;

[0063] SS2: The main circuit is in the discharge state. When forced disconnection is required, the power relay K1 must be disconnected first according to the system definition, and the system stops working. The power relay K1 disconnection signal is detected through the cross-type isolation acquisition circuit, and the contact performance of the current power relay K1 after the action is detected to be normal;

[0064] SS3: Main circuit closing process: According to system requirements, the power relay K1 and the power relay K2 must be closed normally, and the contacts of the power relay K1 and the power relay K2 must be normal after system detection, then the system can operate normally and enter the next step of charging and discharging process.

[0065] During the charging and discharging process or in the static state of the main circuit, the system detects the disconnection (closing) state of the relay contacts in real time, and adopts the cross-isolation detection technology of the present invention to upload the relay state to the MUC in real time. The MCU analyzes and processes the state information of the power relay K1 and the power relay K2, and issues control commands in real time according to the system requirements to ensure the safety and reliability of the main circuit system.

[0066] In the charging and discharging circuit control method, the system detects whether the contact performance of the power relay K1 and the power relay K2 is normal, including the following steps:

[0067] S1: abnormal charging control and detection:

[0068] When the system is working normally at time t1, the power relay K1 and the power relay K2 are in the closed state, and the inverter PCS is working normally;

[0069] At time t2, due to the system alarm protection, the power relay K2 is disconnected, the power relay K1 is closed normally, and the inverter PCS is in standby or shutdown. During this period, the detection circuit automatically tests the contact status of the power relay K2. The detection result is processed by the data unit and uploaded to the MCU for analysis and processing. If the power relay K2 is normal, it is closed. If the power relay K2 is abnormal, it remains disconnected and is replaced manually.

[0070] At t3, the power relay K2 is detected to be normal and closed, and the inverter PCS can be started to work normally after a delay according to the system requirements;

[0071] S2: Abnormal discharge control and detection:

[0072] When the system is working normally at time t1, power relay K1 and power relay K2 are in a closed state, and the PCS is working normally.

[0073] At time t2, due to the system alarm protection, the power relay K1 is disconnected, the power relay K2 is closed normally, and the PCS is in standby or shut down.

[0074] During this period, the detection circuit automatically tests the contact status of the power relay K1. The detection results are processed by the data unit and uploaded to the MCU for analysis and processing. If the power relay K1 is normal, it is closed. If K1 is abnormal, it remains disconnected and is replaced manually;

[0075] At t3, it is detected that the power relay K1 is normal and closed, and the PCS can be started to work normally after a delay according to the system requirements.

[0076] The main circuit power relay K1 and power relay K2 are controlled by MCU. According to the different working modes of the main circuit, such as charging and discharging, different control sequences are adopted to disconnect (close) the relays respectively, so as to ensure that the relay maintains good arc extinguishing ability in one direction, prevent the stress of instantaneous peak voltage and current when the main circuit is disconnected (closed), and prevent oxidation and adhesion of the relay contacts.

[0077] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0078] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A control method for a dual-relay controlled charging and discharging circuit, It is characterized in that The dual-relay controlled charging and discharging circuit includes: a battery charging and discharging main circuit and a relay detection control component; the battery charging and discharging main circuit is composed of a battery pack and a current collector RL, a fuse RF, a power relay K1, a power relay K2, a circuit breaker QF and an inverter PCS connected in the circuit; the relay detection control component includes a cross-type isolation acquisition circuit, a data processing unit, a control unit and an MCU, and the output ends of the cross-type isolation acquisition circuit and the MCU are connected to the data processing unit, and the output end of the data processing unit is connected to the control unit by wires, the output end of the control unit is electrically connected to the input ends of the power relay K1 and the power relay K2, the power relay K1 and the power relay K2 are both polarized relays, and the inverter PCS is a storage A bidirectional inverter can be used, the cross-type isolation acquisition circuit is used to collect the status of the power relay K1 and the power relay K2 in real time, and the cross-type isolation acquisition circuit is also used to transmit the collected status information to the MCU; the MCU is used to analyze and process the status information of the relay, and issue control commands in real time according to system requirements; the MCU adopts an external power supply mode to improve the efficiency of the control circuit itself and the voltage constraint of the control chip power supply, which is more flexible in application, reduces interference, and increases the reliability of the control circuit; the data processing unit is used to receive the control command issued by the MCU, process the control command, and then transmit it to the control unit; the control unit is used to receive the control signal transmitted by the data processing unit, and control the opening and closing of the power relay K1 and the power relay K2; The control method includes a relay detection method and a charge and discharge circuit control method; The relay detection method comprises the following steps: SS1: When entering the main circuit relay detection normally, the power relay K1, power relay K2 and circuit breaker QF are all in the closed state; SS2: The inverter is in shutdown or standby state. The system disconnects the power relay K1 and closes the power relay K2 according to the detection procedure, detects the Uad voltage, and determines whether the power relay K1 is bonded; SS3: disconnect the power relay K2, close the power relay K1, detect the Ubc voltage, determine whether the power relay K2 is bonded, and upload the detection data to the MCU for analysis and processing in real time; The charging and discharging circuit control method comprises the following steps: SS1: The main circuit is in the charging state. When forced disconnection is required, the power relay K2 must be disconnected first according to the system definition, and the system stops working. The power relay K2 disconnection signal is detected through the cross-type isolation acquisition circuit, and the contact performance of the current power relay K2 after the action is detected to be normal; SS2: The main circuit is in the discharge state. When forced disconnection is required, the power relay K1 must be disconnected first according to the system definition, and the system stops working. The power relay K1 disconnection signal is detected through the cross-type isolation acquisition circuit, and the contact performance of the current power relay K1 after the action is detected to be normal; SS3: Main circuit closing process: According to system requirements, the power relay K1 and the power relay K2 must be closed normally, and the contacts of the power relay K1 and the power relay K2 must be normal after system detection, then the system can operate normally and enter the next step of charging and discharging process.

2. A control method for a dual-relay controlled charging and discharging circuit according to claim 1, It is characterized in that In the charging and discharging circuit control method, the system detects whether the contact performance of the power relay K1 and the power relay K2 is normal, including the following steps: S1: abnormal charging control and detection: When the system is working normally at time t1, the power relay K1 and the power relay K2 are in the closed state, and the inverter PCS is working normally; At time t2, due to the system alarm protection, the power relay K2 is disconnected, the power relay K1 is closed normally, and the inverter PCS is in standby or shutdown. During this period, the detection circuit automatically tests the contact status of the power relay K2. The detection result is processed by the data unit and uploaded to the MCU for analysis and processing. If the power relay K2 is normal, it is closed. If the power relay K2 is abnormal, it remains disconnected and is replaced manually. At t3, the power relay K2 is detected to be normal and closed, and the inverter PCS can be started to work normally after a delay according to the system requirements; S2: Abnormal discharge control and detection: When the system is working normally at time t1, power relay K1 and power relay K2 are in the closed state, and PCS is working normally; At time t2, due to the system alarm protection, the power relay K1 is disconnected, the power relay K2 is closed normally, and the PCS is in standby or shutdown. During this period, the detection circuit automatically tests the contact status of the power relay K1. The detection result is processed by the data unit and uploaded to the MCU for analysis and processing. The power relay K1 is normal and closed, and K1 is abnormal and remains disconnected and is manually replaced; At t3, it is detected that the power relay K1 is normal and closed, and the PCS can be started to work normally after a delay according to the system requirements.

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