A thermoelectric cooling control circuit and system for a car charging pile relay

Abstract

The application relates to a thermoelectric cooling control circuit and system for a relay of an automobile charging pile, and belongs to the technical field of power electronics. The circuit comprises a relay control module for outputting a relay control signal; a temperature detection module connected with the relay control module and used for being turned on when the temperature of a shell of the relay reaches a preset threshold; and a thermoelectric refrigeration driving module connected with the temperature detection module and the relay control module respectively, used for receiving the relay control signal and driving a thermoelectric refrigeration piece to work based on the relay control signal when the temperature detection module is turned on, so as to reduce the temperature of the relay. The application can efficiently reduce the temperature of the relay, prolong the service life of the relay, and guarantee the use safety of the charging pile.

Description

Technical Field

[0001] This application relates to the field of power electronics, and in particular to a thermoelectric cooling control circuit and system for an automotive charging pile relay. Background Technology

[0002] Currently, during high-current charging, the relays inside the car charging station generate a lot of heat during frequent switching. If the heat cannot be dissipated in time, the relay temperature may become too high, affecting the relay's operational stability and lifespan, and potentially threatening the safety of other components inside the charging station.

[0003] For relay temperature control and heat dissipation, existing methods generally involve using a simple fan for forced cooling or relying on the natural heat dissipation of the relay casing. However, these methods often have shortcomings. Fans consume a lot of energy and generate a lot of noise when running continuously, and their heat dissipation efficiency decreases after dust accumulates. Natural heat dissipation, on the other hand, cannot effectively control the relay temperature under high-temperature conditions, and the relay may still experience performance degradation due to overheating. Therefore, there is room for improvement. Utility Model Content

[0004] This application provides a thermoelectric cooling control circuit and system for automotive charging pile relays, which can efficiently reduce the temperature of the relay and improve its service life while ensuring the safety of the charging pile.

[0005] A thermoelectric cooling control circuit for a car charging pile relay includes: The relay control module is used to output relay control signals. A temperature detection module, connected to the relay control module, is used to activate the relay when the temperature of the relay housing reaches a preset threshold. The thermoelectric cooling drive module is connected to the temperature detection module and the relay control module respectively. It is used to receive the relay control signal and drive the thermoelectric cooling chip to work based on the relay control signal when the temperature detection module is turned on, so as to reduce the relay temperature.

[0006] By adopting the above technical solution, the semiconductor cooling chip can be turned on and off according to the working state and shell temperature of the relay, thereby achieving relay cooling and low power consumption, avoiding accelerated aging of the relay due to high temperature, and effectively extending the service life and operational reliability of the relay.

[0007] Optionally, the relay control module includes a diode D1 and a relay RL1; The first input terminal of the relay RL1 is connected to the first input terminal of the external power supply, the second input terminal of the relay RL1 is connected to the second input terminal of the external power supply, the first coil terminal of the relay RL1 is connected to the first DC power supply signal, the second coil terminal of the relay RL1 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the junction of the first DC power supply signal and the first coil terminal of the relay RL1, and the second coil terminal of the relay RL1 outputs the relay control signal.

[0008] By adopting the above technical solution, a reliable working state is obtained with the simplest circuit by directly using the endpoints of the relay coil as the status signal. At the same time, the diode design can effectively absorb the reverse electromotive force generated when the coil is de-energized, thereby protecting the front-end drive circuit and improving the electrical stability and durability of the entire system.

[0009] Optionally, the temperature detection module includes a temperature control switch SW1 and a resistor R1; One end of the temperature control switch SW1 is connected to the second DC power supply signal, and the other end of the temperature control switch SW1 is connected to one end of the resistor R1. The other end of the resistor R1 is connected to the thermoelectric refrigeration drive module.

[0010] By adopting the above technical solution, a temperature detection module is constructed using a temperature control switch and a resistor, providing a simple, low-cost, and fast-responding pure hardware temperature monitoring solution. It does not require complex software control, has high reliability, and strong anti-interference capability.

[0011] Optionally, the thermoelectric cooling drive module includes a MOS transistor Q1 and a TEC thermoelectric cooling chip; The gate of the MOS transistor Q1 is connected to the other end of the resistor R1, the source of the MOS transistor Q1 is connected to the relay control signal, the drain of the MOS transistor Q1 is connected to the negative terminal of the TEC thermoelectric cooler, and the positive terminal of the TEC thermoelectric cooler is connected to the third DC power supply signal.

[0012] By adopting the above technical solution, a hardware AND gate logic is cleverly constructed by connecting the source of the MOSFET to the relay control signal. That is, it can only be turned on when the gate is high and the source is low. The core control target is achieved without adding an extra logic chip, which greatly reduces the circuit complexity and cost.

[0013] Optionally, the thermoelectric cooling control circuit further includes a relay control drive module, which includes a resistor R2 and a transistor T1. One end of the resistor R2 is connected to an external control signal, the other end of the resistor R2 is connected to the base of the transistor T1, the collector of the transistor T1 is connected to the relay control signal, and the emitter of the transistor T1 is connected to the ground terminal.

[0014] By adopting the above technical solution and adding a relay control drive module composed of resistor R2 and transistor T1, a low-power external control signal can be used to control the on / off state of the high-current relay coil, thereby achieving effective isolation and drive of weak current to strong current. This allows the cooling system to be easily integrated into the main control system of the car charging pile, improving the system's compatibility and scalability.

[0015] Optionally, the relay control drive module further includes a resistor R3; One end of the resistor R3 is connected to the junction of the resistor R2 and the base of the transistor T1, and the other end of the resistor R3 is connected to the junction of the emitter of the transistor T1 and the ground terminal.

[0016] By adopting the above technical solution, and by adding resistor R3 as a pull-down resistor for the base of transistor T1 in the relay control drive module, it can be ensured that the base of transistor T1 is reliably pulled to a low level when the external control signal is missing, floating, or in a high impedance state, thereby keeping the transistor in a clear cut-off state. This effectively prevents relay malfunctions caused by signal interference or instability, and greatly enhances the control certainty and the operational safety of the entire system.

[0017] Optionally, the temperature control switch SW1 is model KSD9700, and the preset threshold is 50℃.

[0018] By adopting the above technical solution, selecting a mature temperature control switch model and setting the threshold to 50℃, the accuracy of temperature detection and product consistency are ensured, while also selecting an operating point that achieves the best balance between preventive protection and energy saving.

[0019] A thermoelectric cooling control system for an automotive charging pile relay includes a cooling fan and a thermoelectric cooling control circuit as described above.

[0020] Optionally, the cooling fan is coupled to the hot end of the TEC thermoelectric cooler and is turned on when the MOSFET Q1 is turned on.

[0021] By adopting the above technical solution, and by coupling the cooling fan with the hot end of the TEC thermoelectric cooler, the heat accumulation point generated during TEC operation can be forcibly cooled in a targeted manner. This effectively solves the problem of heat accumulation in the TEC itself, ensuring that the hot and cold ends of the TEC can maintain a sufficient temperature difference, maximizing its cooling efficiency. Furthermore, by synchronizing the cooling fan with the MOSFET Q1 when it is turned on, the operation of the fan and the cooling action of the TEC can be completely synchronized, thereby achieving management of auxiliary heat dissipation power consumption, avoiding ineffective fan operation, and further improving the overall energy efficiency of the system.

[0022] In summary, this application includes at least the following beneficial effects: 1. The semiconductor cooling chip can be turned on and off according to the relay's operating status and housing temperature, thereby achieving relay cooling and low power consumption, preventing the relay from aging prematurely due to high temperature, and effectively extending the relay's service life and operational reliability.

[0023] 2. By coupling the cooling fan to the hot end of the TEC thermoelectric cooler, forced heat dissipation can be applied to the heat accumulation points generated during TEC operation, effectively solving the heat accumulation problem of the TEC itself. This ensures that the hot and cold ends of the TEC can maintain a sufficient temperature difference, maximizing its cooling efficiency. Furthermore, by synchronizing the cooling fan with the MOSFET Q1 when it is turned on, the operation of the fan and the cooling action of the TEC can be completely synchronized, thereby achieving management of auxiliary heat dissipation power consumption, avoiding ineffective fan operation, and further improving the overall energy efficiency of the system. Attached Figure Description

[0024] Figure 1 This is a structural block diagram of one embodiment of the thermoelectric cooling control circuit for an automotive charging pile relay in this application. Figure 2 This is a schematic diagram of the circuit structure of the relay control module in the thermoelectric cooling control circuit of this application embodiment; Figure 3 This is a schematic diagram of the circuit structure of the temperature detection module and the thermoelectric cooling drive module in the thermoelectric cooling control circuit of this application embodiment; Figure 4 This is a schematic diagram of the circuit structure of the relay control drive module in the charging pile relay safety detection circuit of this application embodiment. Detailed Implementation

[0025] This application is in conjunction with the appendix Figure 1 -Appendix Figure 4 Let's take an example to explain in more detail.

[0026] Example 1 This application discloses a thermoelectric cooling control circuit for a relay used in an automotive charging station. As one embodiment of the thermoelectric cooling control circuit, see attached... Figure 1 As shown, it includes: a relay control module for outputting relay control signals; As attached Figure 2 As shown, in one embodiment of the relay control module, the relay control module includes a diode D1 and a relay RL1; the first input terminal of the relay RL1 is connected to the first input terminal of an external power supply, the second input terminal of the relay RL1 is connected to the second input terminal of the external power supply, the first coil terminal of the relay RL1 is connected to a first DC power supply signal, the second coil terminal of the relay RL1 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the junction of the first DC power supply signal and the first coil terminal of the relay RL1, and the second coil terminal of the relay RL1 outputs the relay control signal.

[0027] In this embodiment, the normally open contact 3 of relay REL1 is connected to the high-voltage input terminal L_IN of the charging pile, and the common terminal 4 is connected to the high-voltage output terminal L_OUT. When relay REL1 is not energized, contacts 3 and 4 are disconnected; when energized, the contacts close, connecting L_IN and L_OUT to form a charging circuit. The coil terminal 1 of relay REL1 is connected to a first DC power supply signal, such as +12V, and the coil terminal 2 serves as the control input terminal and also as the output node of the relay control signal OUT_RLY1. The anode of the freewheeling diode D1 is connected to coil terminal 2, and its cathode is connected to coil terminal 1, i.e., the +12V power supply, thus forming a coil drive circuit.

[0028] Specifically, the relay control module controls the level of coil terminal 2 to drive the contacts of relay REL1 to close or open, thereby controlling the on / off state of the charging pile's main circuit. The level change of coil terminal 2 serves as the control basis for downstream circuits. When the external drive circuit pulls coil terminal 2 low (e.g., to ground), the coil of relay REL1 is energized and engaged. When the pull-down of coil terminal 2 is released, its level returns to high due to the connection with the +12V power supply. Therefore, the high or low level of the OUT_RLY1 signal directly and reliably reflects the operating state of relay REL1—open or closed. Furthermore, a freewheeling diode D1 is connected in parallel across the coil to provide a discharge path for the magnetic field energy stored in the coil when it is de-energized, absorbing the generated reverse electromotive force and protecting the components of the drive circuit from high-voltage surges.

[0029] The temperature detection module is connected to the relay control module and is used to turn on the relay when the temperature of the relay housing reaches a preset threshold.

[0030] As attached Figure 3As shown, as one embodiment of the temperature detection module, the temperature detection module includes a temperature control switch SW1 and a resistor R1; wherein, the temperature control switch SW1 is model KSD9700; one end of the temperature control switch SW1 is connected to a second DC power supply signal, the other end of the temperature control switch SW1 is connected to one end of the resistor R1, and the other end of the resistor R1 is connected to the thermoelectric cooling drive module.

[0031] In this embodiment, the temperature control switch SW1 is a normally open temperature-sensitive switch, such as the KSD9700 component, which is normally open at 50°C. It is mounted on the housing of the relay REL1, with one end connected to a second DC power supply signal, such as +12V, and the other end connected to the thermoelectric cooling drive module through a current-limiting resistor R1.

[0032] Specifically, this temperature detection module constitutes a simple and reliable temperature threshold trigger. When the operating temperature of relay REL1 is below 50℃, the internal contacts of temperature control switch SW1 remain open, and its output is either low or floating. Once the relay casing temperature rises to 50℃ due to continuous high current operation, the internal contacts of SW1 automatically close, outputting a high-level signal through resistor R1 from the +12V power supply as a command to start cooling. The presence of resistor R1 provides appropriate drive current to subsequent circuits and prevents power supply surges when SW1 closes.

[0033] The thermoelectric cooling drive module is connected to the temperature detection module and the relay control module respectively. It is used to receive the relay control signal and drive the thermoelectric cooling chip to work based on the relay control signal when the temperature detection module is turned on, so as to reduce the relay temperature.

[0034] As attached Figure 3 As shown, as one embodiment of the thermoelectric cooling drive module, the thermoelectric cooling drive module includes a MOSFET Q1 and a TEC thermoelectric cooler; the gate of the MOSFET Q1 is connected to the other end of the resistor R1, the source of the MOSFET Q1 is connected to the relay control signal, the drain of the MOSFET Q1 is connected to the negative terminal of the TEC thermoelectric cooler, and the positive terminal of the TEC thermoelectric cooler is connected to the third DC power supply signal.

[0035] In this embodiment, MOSFET Q1 is preferably an N-channel enhancement-mode MOSFET, serving as the core switching element for driving the TEC thermoelectric cooler. Its gate is connected to the other end of resistor R1 to receive a temperature over-limit signal from the temperature detection module. Its source is connected to the relay control signal OUT_RLY1 output by the relay control module, and its drain is connected to the negative terminal TEC- of the TEC thermoelectric cooler. The TEC thermoelectric cooler is attached to the housing of relay REL1 for active heat dissipation, and its positive terminal TEC+ is connected to a third DC power supply signal, such as +12V.

[0036] Specifically, when the relay is not working, the coil of relay REL1 is not driven, and the relay control signal OUT_RLY1 is at a high level, such as +12V. This high-level signal is applied to the source of MOSFET Q1. Since the source potential of MOSFET Q1 is already high, regardless of whether its gate receives a high-level or low-level signal from the temperature detection module, its gate-source voltage Vgs cannot meet the conduction condition, i.e., Vgs is less than or equal to 0. Therefore, MOSFET Q1 will always be in the off state. At this time, the circuit to the TEC thermoelectric cooler is cut off, and the TEC thermoelectric cooler does not work. When the relay is working, the relay control signal OUT_RLY1 is pulled low, such as close to GND, and this low-level signal is applied to the source of MOSFET Q1. At this time, whether MOSFET Q1 can conduct depends entirely on the level of its gate, that is, entirely determined by the state of the temperature detection module.

[0037] Furthermore, if the relay temperature is below a preset threshold, such as 50°C, the temperature control switch SW1 in the temperature detection module is open, and the gate of MOSFET Q1 remains at a low level without a high-level drive. Therefore, MOSFET Q1 is still in the off state, and the TEC thermoelectric cooler is not working. If the relay temperature reaches or exceeds the preset threshold, such as 50°C, the temperature control switch SW1 in the temperature detection module closes, outputting a high-level signal to the gate of MOSFET Q1. Since the source of MOSFET Q1 is at a low level at this time, its gate-source voltage Vgs is much greater than its turn-on threshold, and MOSFET Q1 immediately turns on. After turning on, current flows from the +12V power supply through the TEC thermoelectric cooler, then through the drain and source of MOSFET Q1, and finally to the low-level OUT_RLY1 node, forming a complete drive circuit. The TEC thermoelectric cooler starts working, actively cooling the relay.

[0038] As attached Figure 4As shown, as a further embodiment of the thermoelectric cooling control circuit, the thermoelectric cooling control circuit also includes a relay control drive module, which includes a resistor R2 and a transistor T1; one end of the resistor R2 is connected to an external control signal, the other end of the resistor R2 is connected to the base of the transistor T1, the collector of the transistor T1 is connected to the relay control signal, and the emitter of the transistor T1 is connected to the ground terminal.

[0039] As attached Figure 4 As shown, as a further embodiment of the relay control drive module, the relay control drive module also includes a resistor R3; one end of the resistor R3 is connected to the connection between the resistor R2 and the base of the transistor T1, and the other end of the resistor R3 is connected to the connection between the emitter of the transistor T1 and the ground terminal.

[0040] In this embodiment, when the external control signal OUT1 outputs a high level, current flows into the base of T1 through R2, causing T1 to saturate and conduct. Its collector is forcibly pulled to a low level close to GND, thereby energizing and engaging the coil of relay REL1. When OUT1 outputs a low level or is in a high-impedance state, resistor R3 reliably pulls the base potential of T1 to a low level, ensuring that T1 is in the off state, thereby releasing control over the OUT_RLY1 node and de-energizing the relay coil. Resistor R2 is used to limit the base current, protecting the transistor and MCU port; resistor R3 effectively prevents T1 from being accidentally triggered when the OUT1 signal is unstable or floating, enhancing the circuit's anti-interference capability and stability.

[0041] The implementation principle of this embodiment is as follows: The entire thermoelectric cooling control circuit outputs relay control signals through the relay control module, and the temperature detection module monitors the relay housing temperature in real time. When the relay is working and the housing temperature has not reached 50°C, the temperature control switch SW1 is not turned on, the MOSFET Q1 is cut off, and the TEC thermoelectric cooler does not work, relying on natural heat dissipation; when the temperature reaches 50°C, the temperature control switch SW1 is turned on, and the signal is transmitted to the MOSFET Q1 through the resistor R1, causing it to turn on, and the TEC thermoelectric cooler starts working, reducing the relay temperature, reducing power consumption, reducing noise and dust accumulation, and improving the reliability and service life of the charging pile.

[0042] Example 2 The thermoelectric cooling control system for automotive charging pile relays provided in this application includes a cooling fan and a thermoelectric cooling control circuit as described in Embodiment 1. The cooling fan is coupled to the hot end of the TEC thermoelectric cooler. This arrangement ensures that when the MOSFET Q1 is turned on and the TEC thermoelectric cooler starts working, the cooling fan will turn on simultaneously, effectively dissipating the heat generated at the hot end of the TEC thermoelectric cooler and improving cooling efficiency.

[0043] Cooling fans are typically axial fans, characterized by using the rotation of blades to propel airflow, resulting in a large air volume and relatively low noise. Other types of fans, such as centrifugal fans, can be used, as long as they meet the cooling requirements. The coupling between the cooling fan and the hot end of the TEC thermoelectric cooler can be achieved through a thermally conductive material or through an airflow design that directs the airflow from the fan directly to the hot end of the TEC thermoelectric cooler.

[0044] The implementation principle of this embodiment is as follows: a cooling fan is added to the thermoelectric cooling control circuit. When the TEC thermoelectric cooler is working, the cooling fan turns on simultaneously to quickly dissipate the heat from the hot end of the TEC thermoelectric cooler, preventing heat accumulation from affecting the cooling effect. This design makes the cooling efficiency of the entire system higher, can more effectively reduce the temperature of the relay, and further improves the reliability and stability of the charging pile. It is an optimization and improvement of existing technology.

[0045] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A thermoelectric cooling control circuit for a relay in an automotive charging station, characterized in that, include: The relay control module is used to output relay control signals. A temperature detection module, connected to the relay control module, is used to activate the relay when the temperature of the relay housing reaches a preset threshold. The thermoelectric cooling drive module is connected to the temperature detection module and the relay control module respectively. It is used to receive the relay control signal and drive the thermoelectric cooling chip to work based on the relay control signal when the temperature detection module is turned on, so as to reduce the relay temperature.

2. The thermoelectric cooling control circuit according to claim 1, characterized in that: The relay control module includes a diode D1 and a relay RL1; The first input terminal of the relay RL1 is connected to the first input terminal of the external power supply, the second input terminal of the relay RL1 is connected to the second input terminal of the external power supply, the first coil terminal of the relay RL1 is connected to the first DC power supply signal, the second coil terminal of the relay RL1 is connected to the anode of the diode D1, the cathode of the diode D1 is connected to the junction of the first DC power supply signal and the first coil terminal of the relay RL1, and the second coil terminal of the relay RL1 outputs the relay control signal.

3. The thermoelectric cooling control circuit according to claim 1, characterized in that: The temperature detection module includes a temperature control switch SW1 and a resistor R1; One end of the temperature control switch SW1 is connected to the second DC power supply signal, and the other end of the temperature control switch SW1 is connected to one end of the resistor R1. The other end of the resistor R1 is connected to the thermoelectric refrigeration drive module.

4. The thermoelectric cooling control circuit according to claim 3, characterized in that: The thermoelectric cooling drive module includes a MOS transistor Q1 and a TEC thermoelectric cooling chip; The gate of the MOS transistor Q1 is connected to the other end of the resistor R1, the source of the MOS transistor Q1 is connected to the relay control signal, the drain of the MOS transistor Q1 is connected to the negative terminal of the TEC thermoelectric cooler, and the positive terminal of the TEC thermoelectric cooler is connected to the third DC power supply signal.

5. The thermoelectric cooling control circuit according to claim 1, characterized in that: The thermoelectric cooling control circuit also includes a relay control drive module, which includes a resistor R2 and a transistor T1. One end of the resistor R2 is connected to an external control signal, the other end of the resistor R2 is connected to the base of the transistor T1, the collector of the transistor T1 is connected to the relay control signal, and the emitter of the transistor T1 is connected to the ground terminal.

6. The thermoelectric cooling control circuit according to claim 5, characterized in that: The relay control drive module also includes a resistor R3; One end of the resistor R3 is connected to the junction of the resistor R2 and the base of the transistor T1, and the other end of the resistor R3 is connected to the junction of the emitter of the transistor T1 and the ground terminal.

7. The thermoelectric cooling control circuit according to claim 3, characterized in that: The temperature control switch SW1 is model KSD9700, and the preset threshold is 50℃.

8. A thermoelectric cooling control system for an automotive charging pile relay, characterized in that, It includes a cooling fan and a thermoelectric cooling control circuit as described in any one of claims 1-7.

9. The thermoelectric cooling control system according to claim 8, characterized in that: The cooling fan is coupled to the hot end of the TEC thermoelectric cooler and is used to turn on when the MOSFET Q1 is turned on.

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