Power exchange station liquid cooling control system based on PLC control

Abstract

The invention belongs to the technical field of new energy heavy truck chassis battery swap stations, and particularly relates to a PLC control-based battery swap station liquid cooling control system, which comprises a PLC controller, and the PLC controller comprises a signal acquisition unit, a logic control unit, a data storage unit, a control output unit, a bus and a 485 communication port. And the signal acquisition is realized by a plurality of sensors for acquiring liquid cooling data of the battery swap station. According to the liquid cooling control system for the battery swap station based on PLC control, the actual state of each sensor is obtained through conversion calculation according to the collected signals of the temperature sensor, the pressure sensor, the liquid level sensor and the like through the PLC, a compressor and an outer fan are automatically controlled through Modbus communication to control the work of a refrigerating system, the liquid outlet temperature is kept within a set value range, and the working efficiency is improved. The superheat degree of the system is calculated according to the exhaust temperature of the compressor, and the superheat degree of the system is controlled through an expansion valve controller; and finally, the cooling liquid output by the system is controlled by controlling the rotating speed of the water pump to ensure that sufficient cooling liquid flows into the charging bag for cooling.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy heavy truck chassis swapping stations, and particularly to a liquid cooling control system for a swapping station based on PLC control. Background Art

[0002] With the increasing environmental protection requirements and the continuous development of new energy technologies, electric heavy trucks are being applied more and more widely. As a key facility for quickly replenishing energy for electric heavy trucks, the efficient and stable operation of heavy truck swapping stations is crucial. During the charging process of heavy truck battery packs, a large amount of heat is generated by the batteries. If the heat cannot be dissipated in a timely and effective manner, it will seriously affect the performance and lifespan of the batteries, and may even cause safety problems.

[0003] Currently, there are many deficiencies in the heat dissipation methods of traditional heavy truck swapping stations: 1. The heat dissipation efficiency of air-cooling systems is relatively low, making it difficult to meet the heat dissipation requirements of high-power batteries; some simple liquid cooling systems lack precise control and cannot flexibly adjust the heat dissipation power according to the actual heat generation of the batteries, resulting in energy waste or insufficient heat dissipation. Therefore, it is of great practical significance to develop a highly efficient, intelligent, and precisely controlled liquid cooling system for heavy truck swapping stations; 2. The degree of automation of the liquid cooling system is directly related to the safety, economy, and sustainability of heavy truck swapping stations. At present, with the rapid popularization of the battery swapping mode, the existing liquid cooling systems of swapping stations have low intelligence, high operation costs, and low adaptability and scalability. Summary of the Invention

[0004] In order to overcome the defects of the above-mentioned prior art pointed out, the inventor of the present invention has conducted in-depth research and completed the present invention after a large amount of creative labor.

[0005] Specifically, the technical problems to be solved by the present invention are: to provide a liquid cooling control system for a swapping station based on PLC control to solve the problems that the current swapping stations cannot accurately and automatically control the outlet liquid temperature and flow rate of the liquid cooling system according to temperature changes, and cannot provide a coolant with a stable flow rate and temperature to the battery pack end to reduce the temperature during battery pack charging; the existing swapping stations cannot accurately control the operating parameters of the liquid cooling system to achieve efficient heat dissipation, reduce energy consumption, and improve the stability and reliability of the system.

[0006] To solve the above technical problems, the present invention provides the following technical solution: A liquid cooling control system for a swapping station based on PLC control, including a PLC controller, and the PLC controller includes signal acquisition, logic control, data storage, control output, a bus, and a 485 communication port; The signal acquisition is performed by multiple sensors for collecting the liquid cooling data of the charging and swapping stations, including an ambient temperature sensor, an exhaust temperature sensor, a suction temperature sensor, an inlet water temperature sensor, an outlet water temperature sensor, a water tank liquid level sensor, an exhaust pressure sensor, a suction pressure sensor, an inlet water pressure sensor, and an outlet water pressure sensor.

[0007] As an improved technical solution, the control output controls several end solenoid valves, including end solenoid valve 1, end solenoid valve 2, end solenoid valve 3, end solenoid valve 4, end solenoid valve 5, and end solenoid valve 6.

[0008] As an improved technical solution, the control output also controls an electronic expansion valve 1, a cooling fan, and a compressor heating tape.

[0009] As an improved technical solution, the 485 communication port controls a compressor, a water pump, and an external fan.

[0010] After adopting the above technical solution, the beneficial effects of the present invention are as follows: 1. By increasing the design of the liquid cooling operation temperature and safety of the charging and swapping station, through the automatic control of the PLC, the present invention can accurately monitor in real time with the help of sensors, make a rapid response, and automatically adjust the flow rate and temperature of the coolant, so as to ensure that the charging battery is always in a safe working temperature range and effectively avoid the occurrence of thermal runaway problems. In contrast, the liquid cooling system with low automation degree is prone to damage the battery due to excessive temperature due to the lack of dynamic adjustment ability, and may even cause safety accidents such as fires in severe cases.

[0011] 2. By increasing the design of high energy efficiency and low operating cost of the liquid cooling of the charging and swapping station, the liquid cooling control system can dynamically adjust the cooling capacity of the refrigeration system according to the actual load conditions of the charging and swapping station, such as the charge and discharge status and quantity of the batteries. It can significantly reduce unnecessary energy consumption, reduce the high-temperature aging of the battery by precisely controlling the temperature during battery charging, thereby extending the service life of the battery and reducing the operating cost of the charging and swapping station.

[0012] 3. By increasing the design of the adaptability and scalability of the liquid cooling control of the charging and swapping station, the liquid cooling control system can automatically adjust the operation strategy according to the ambient temperature changes in different seasons and regions. Whether in the cold winter in the north or the hot summer in the south, it can ensure the stable operation of the system. The liquid cooling control system of the present invention can adapt to the thermal management requirements of new batteries by software upgrade or parameter update, avoiding repeated hardware investment. Description of the Drawings

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying 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 accompanying drawings can be obtained based on these drawings. Among them: Figure 1 It is a schematic structural diagram of the architecture of the liquid cooling control system of the power exchange station based on PLC control of the present invention. Specific embodiments

[0014] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0015] 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.

[0016] At the same time, the meaning of "and / or" or "and / or" that appears throughout the text is that it includes three solutions. Taking "A and / or B" as an example, it includes solution A, or solution B, or a solution that satisfies both A and B at the same time.

[0017] In addition, the descriptions such as "first" and "second" 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 of these features. In addition, the technical solutions between the 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 is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0018] As Figure 1 shown, this embodiment provides a liquid cooling control system for a power exchange station based on PLC control. This liquid cooling control system for a power exchange station based on PLC control includes a PLC controller, and the PLC controller includes signal acquisition, logic control, data storage, control output, a bus, and a 485 communication port; Signal acquisition is performed by multiple sensors that collect the liquid cooling data of the charging and swapping stations, including ambient temperature sensors, exhaust temperature sensors, intake temperature sensors, inlet water temperature sensors, outlet water temperature sensors, water tank level sensors, exhaust pressure sensors, intake pressure sensors, inlet water pressure sensors, and outlet water pressure sensors.

[0019] In this embodiment, the refrigeration demand calculation is as follows: The PLC calculates the system refrigeration demand based on the collected temperature and the set temperature. The refrigeration demand = 100 × ; where T1 is the collected temperature, Tp is the set temperature, and Ts is the set coefficient.

[0020] As Figure 1 shown, the control output controls several terminal solenoid valves, including terminal solenoid valve 1, terminal solenoid valve 2, terminal solenoid valve 3, terminal solenoid valve 4, terminal solenoid valve 5, and terminal solenoid valve 6.

[0021] As Figure 1 shown, the control output also controls the electronic expansion valve 1, the cooling fan, and the compressor heating tape.

[0022] Return-to-origin control of the expansion valve: Since there is no feedback signal for the actual position of the expansion valve, return-to-origin control is required before the system is powered on or during refrigeration control. The specific control logic is as follows: After power-on or when refrigeration is started, first give the driver a forward rotation signal to open it to the maximum opening, and then give the driver a reverse rotation signal to close the expansion valve to the minimum opening; Regulation of the expansion valve: The regulation of the expansion valve is in the standard PID regulation mode. The electronic expansion valve is closed-loop regulated according to the exhaust pressure of the system and the calculated superheat degree to ensure that the system superheat degree is maintained within the set value range. The PID calculation formula is: Where: u(t) is the output of the controller, corresponding to the control signal for the opening of the expansion valve; Kp is the proportionality coefficient; e(t) is the deviation of the system, that is, the difference between the current superheat degree value and the set superheat degree value; Ti is the integral time constant, and the integral link is mainly used to eliminate the steady-state error of the system; Td is the differential time constant, and the differential term can adjust the output in advance according to the change trend.

[0023] In the liquid cooling system of the heavy truck charging and swapping station, the PLC controller can use the u(t) value as the control opening value of the expansion valve to adjust the opening of the expansion valve in real time to ensure that the system superheat degree is maintained within the set value range.

[0024] In this embodiment, when the ambient temperature is relatively high and the refrigeration demand is greater than the refrigeration startup demand, the PLC controller first controls the external fan to start and maintain a certain rotational speed; then starts the compressor. When the ambient temperature is relatively low and the refrigeration demand is greater than the refrigeration startup demand, the PLC controller first controls the compressor to start and determines whether to start the external fan according to the discharge pressure. When the discharge pressure is greater than the set upper limit pressure, the actual value of the discharge pressure read is used to calculate the rotational speed of the external fan that needs to be output, and the external fan frequency converter is controlled to output through communication, so as to ensure that the discharge pressure is stable within the set value and ensure the safety and stability of the system; the adjustment control of the external fan , the adjustment of the external fan is calculated according to the discharge pressure of the system: F_fan = Where: F_fan: the output frequency of the frequency converter; P_discharge: the actual value of the discharge pressure; P_set: the set discharge pressure threshold for the fan to start; P_Max: the maximum discharge pressure of the system; P_Min: the minimum discharge pressure of the system; The PLC controller controls the output frequency of the fan frequency converter according to the calculated value of F_fan, so as to ensure that the discharge pressure is stable within the set value.

[0025] In this embodiment, the PLC controller controls the output frequency F_water of the water pump frequency converter according to the set number K1 of the opened end solenoid valves, ensuring that the flow rate of the end solenoid valves meets the requirements; F_water = 50 × × u; Where: K: the total number of end solenoid valves, u: the ratio of the maximum flow rate required by the system to the maximum output flow rate of the water pump; In this embodiment, when there is a refrigeration demand, the PLC controller controls the compressor with the set temperature as the target value and the collected water outlet temperature as the actual value for PID adjustment. Since the liquid cooling control system has a large inertia and strong hysteresis, an incremental PID control method is adopted and feedforward control is added.

[0026] The feedforward control establishes a system model and calculates several groups of system data according to the system: from the information such as the number of end solenoid valves put into use, the collected temperature, the ambient temperature, and the water outlet temperature, calculate the steady-state system data under different states and form an array table; the liquid cooling system pre-controls the compressor frequency converter according to the corresponding state in the table, and then performs PID adjustment to the system steady state. Using feedforward control can better control the overshoot of the system and reduce the steady-state adjustment time.

[0027] Incremental PID control: Calculation with the incremental PID formula: Where: u(n): the output of the controller at the nth sampling moment; Kp: proportionality coefficient; e(n): the deviation at the nth sampling moment, i.e., the difference between the set value and the actual value; Ki = Kp / Ti: Ki is the integral coefficient, and Ti is the integral time constant; Kd = Kp×Td: Kd is the derivative coefficient, and Td is the derivative time constant.

[0028] The output of the controller at the (n - 1)th sampling moment is: Subtracting u(n - 1) from u(n) gives the incremental PID formula: In the liquid cooling system of a heavy truck battery swapping station, the PLC controller can calculate Δu(n) according to the incremental PID formula, and then add this increment to the previous control output u(n - 1) to obtain the current control output u(n), thereby controlling the rotational speed of the compressor to achieve precise control of the liquid outlet temperature. The three parameters Kp, Ki, and Kd can be reasonably selected and adjusted according to the actual requirements and debugging results of the system to achieve the best control effect.

[0029] During use, the PLC controller obtains the actual states of each sensor through conversion and calculation based on the signals of sensors such as temperature, pressure, and liquid level collected, automatically controls the compressor and the external fan through Modbus communication to control the operation of the refrigeration system, ensures that the liquid outlet temperature is maintained within the set value range, calculates the superheat degree of the system based on the exhaust temperature of the compressor, and controls the superheat degree of the system through the expansion valve controller; finally, controls the rotational speed of the water pump to control the coolant output by the system to ensure that a sufficient amount of coolant flows into the charging pack for cooling; ensures the stable operation and safety of the battery swapping station.

[0030] It should be understood that the use of these embodiments is only for illustrating the present invention and is not intended to limit the protection scope of the present invention. In addition, it should also be understood that after reading the technical content of the present invention, those skilled in the art can make various changes, modifications, and / or variations to the present invention, and all these equivalent forms also fall within the protection scope defined by the appended claims of this application.

Claims

1. A liquid cooling control system for a battery swap station based on PLC control, comprising a PLC controller, characterized in that: The PLC controller includes signal acquisition, logic control, data storage, control output, bus and 485 communication port; The signal acquisition is composed of multiple sensors that collect liquid cooling data of the battery swap station, including an ambient temperature sensor, an exhaust temperature sensor, an intake temperature sensor, a water inlet temperature sensor, a water outlet temperature sensor, a water tank level sensor, an exhaust pressure sensor, an intake pressure sensor, a water inlet pressure sensor and a water outlet pressure sensor.

2. According to the PLC-controlled liquid cooling control system for a battery swap station according to claim 1, it is characterized in that: The control output controls several end solenoid valves, including end solenoid valve 1, end solenoid valve 2, end solenoid valve 3, end solenoid valve 4, end solenoid valve 5, and end solenoid valve 6.

3. The liquid cooling control system for a battery swap station based on PLC control according to claim 1 is characterized in that: The control output also controls the electronic expansion valve 1, the cooling fan and the compressor heating belt.

4. The liquid cooling control system for a battery swap station based on PLC control according to claim 1 is characterized in that: The 485 communication port is used to control the compressor, water pump and external fan.

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