Current switching circuit

Abstract

The utility model discloses a current switching circuit, which comprises software interlocking control, forced cut-off control, MOS (Metal Oxide Semiconductor) drive and dual power supply switching, the software interlocking control circuit controls the MOS driving circuit through two output ends, and the forced cut-off control circuit is connected with the MOS driving circuit through an input end; the MOS driving circuit comprises two driving circuits which are respectively corresponding to two paths of power supplies. According to the utility model, large current switching is optimized, the stability is high, and compared with a relay, the service life is longer and safer; anti-backflow protection and anti-reverse connection protection are arranged, so that one-way flow of current is ensured; software interlocking ensures single-path power supply output, and misoperation is avoided; the power supply has the functions of self-turn-off and forced turn-off when the microcontroller fails, adapts to different power requirements, and is low in cost and high in reliability.

Description

Technical Field

[0001] The utility model relates to the technical field of direct current power supply or direct current power supply equipment or system, in particular to a current switching circuit. Background Art

[0002] With the rapid development of the logistics industry, refrigerated transportation is becoming increasingly important as a key link to ensure the freshness and safety of goods such as food and medicine. In the process of refrigerated transportation, the refrigerated air-conditioning system is a key equipment to ensure the quality of goods. Since refrigerated transport vehicles often need to travel for a long time, the stability of the power supply of the refrigerated air-conditioning system has become an urgent problem to be solved.

[0003] At present, the refrigeration and air conditioning system on refrigerated transport vehicles mainly relies on the power provided by the car engine to work. However, when the car is turned off or in standby mode, the engine stops working and the refrigeration and air conditioning system loses power supply, resulting in a decrease in refrigeration effect and even affecting the quality and safety of the goods. To solve this problem, engineers have designed a solution that switches to DC_AUX auxiliary power supply when the car is in standby mode to ensure the continuous operation of the refrigeration and air conditioning system.

[0004] In the current market, refrigeration and air conditioning systems mainly use two or more high-power relays to switch power. Although this switching solution solves the problem of power supply to a certain extent, it has many shortcomings.

[0005] First, the cost of using multiple high-power relays for power switching is high. Relays, as electrical control components, are not cheap, especially when multiple relays are required to work together, the cost will rise further. This not only increases the manufacturing cost of refrigerated transport vehicles, but also increases the cost of their subsequent maintenance.

[0006] Secondly, the safety and reliability of the existing solutions cannot be fully guaranteed. Since the relay is prone to sticking during long-term high-current switching, this may cause power switching failure or even circuit failure. In addition, if the operation is improper, the two power supplies may be reversed, which will not only damage the electrical equipment, but also pose a threat to the safety of the operator. Utility Model Content

[0007] The main technical problem solved by the utility model is to provide a current switching circuit, which can reduce the maintenance and replacement costs caused by system failures by improving the stability and reliability of the system.

[0008] In order to solve the above technical problems, a technical solution adopted by the utility model is: providing a current switching circuit, including: a software interlock control circuit, a forced cut-off control circuit, a MOS driving circuit, and a dual power switching circuit; the first output end of the software interlock control circuit is connected to the first input end of the MOS driving circuit, and the second output end is connected to the second input end of the MOS driving circuit; the input end of the forced cut-off control circuit is connected to the third input end of the MOS; the first output end of the MOS driving circuit is connected to the first input end of the forced cut-off control circuit, and the second output end is connected to the second input end of the forced cut-off control circuit; the MOS driving circuit includes a first driving circuit and a second driving circuit; the forced cut-off control circuit includes a first power supply circuit and a second power supply circuit; wherein the first input end of the MOS driving circuit is arranged corresponding to the input end of the first driving circuit, the second input end is arranged corresponding to the first input end of the second driving circuit, and the third input end is arranged corresponding to the second input end of the second driving circuit; the first output end of the MOS driving circuit is arranged corresponding to the output end of the first driving circuit, and the second output end is arranged corresponding to the output end of the second driving circuit.

[0009] Among them, the software interlock control circuit includes: a first enable port Vbat EN, a second enable port AUX_EN, resistors R14, RI5, R17, R18, logic circuits U1A, U1B, U2C, U2D and a ground terminal GND; the first enable port Vbat EN is used to receive the power enable signal in the open path mode of the microprocessor; the second enable port AUX_EN is used to receive the DC power enable signal in the open standby mode of the microprocessor; resistors R14, RI5, R17, R18: used for current limiting, voltage division and filtering functions in the circuit; capacitors C1 and C2: connected in series with resistors R14 and R17 to form a filtering circuit to eliminate noise and ripple in the power signal; logic circuits U1A, U1B, U2C, U2D: form an interlock logic control circuit to determine the power output according to the signal status of the two enable ports; ground terminal GND: serves as a common reference point of the circuit.

[0010] Among them, the MOS driving circuit includes: a MOS first driving circuit for the road power supply Vbat and a MOS second driving circuit for the standby power supply DC_AUX; the MOS first driving circuit for the road power supply Vbat includes: a logic circuit U1C, resistors R1, R8, R11, R12, R13, transistors Q1, Q4, Q7, diode D1, and a Zener diode DZ1; the MOS second driving circuit for the standby power supply DC_AUX includes: a logic circuit U1D, resistors R16, R25, R28, R29, R33, transistors Q8, Q11, Q14, diode D2, and a Zener diode DZ2.

[0011] Among them, the first power supply circuit includes: MOS tubes Q2, Q3, Q15, Q5, Q6, Q16, gate voltage divider resistors R2, R3, R4, R5, R36, R35, R9, R6, R10, R7, R37, R38; the second power supply circuit includes: MOS tubes Q9, Q10, Q17, Q12, Q13, Q18, gate voltage divider resistors R19, R20, R22, R21, R40, R39, R26, R23, R27, R24, R42, R41.

[0012] The forced cut-off control circuit includes: a key switch SW1, resistors R30, R31, R32, R34, a capacitor C3 and a logic circuit U2A.

[0013] The current switching circuit of the utility model is optimized for high current switching and has better stability and reliability. Compared with the traditional relay solution, the utility model can handle high current switching more effectively, reducing the shortened life of the relay due to frequent operation and potential safety problems; the circuit has built-in protection mechanisms against backflow and reverse connection, which effectively avoids the reverse flow of current due to incorrect power connection or abnormal conditions, further improving the safety and stability of the system; through software interlock protection, the circuit ensures that only one power supply can be output at any time, avoiding the problem of simultaneous output of multiple power supplies due to misoperation or system failure. At the same time, when the microcontroller (MCU) fails, the circuit can automatically shut down the output, effectively protecting the safety of the system; the circuit is also equipped with a forced cut-off protection function. When the system is abnormal, the power output can be quickly cut off through manual external operation, so as to respond in time and avoid possible damage or danger; this solution can adapt to power supply requirements of different powers, making the circuit more flexible and versatile, and can be widely used in various occasions requiring current switching; compared with traditional relay solutions, this solution is also more cost-effective, not only can it reduce hardware costs, but also can reduce maintenance and replacement costs caused by system failures by improving system stability and reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a schematic diagram of the module structure of a current switching circuit in an embodiment of the utility model;

[0015] Figure 2 It is a circuit structure schematic diagram of a current switching circuit in an implementation mode of the utility model. DETAILED DESCRIPTION

[0016] See also Figure 1, which is a schematic diagram of a module structure of a current switching circuit in an embodiment of the utility model. The current switching circuit 10 comprises: a software interlock control circuit 11, a forced cut-off control circuit 12, a MOS driving circuit 13, and a dual power supply switching circuit 14.

[0017] The current switching circuit 10 can be applied to a circuit that requires two power supplies for switching. In the present embodiment, the current switching circuit 10 is applied to large current switching between road use and standby modes of a transport refrigerated vehicle air conditioner.

[0018] The first output end of the software interlock control circuit 11 is connected to the first input end of the MOS drive circuit 13, and the second output end is connected to the second input end of the MOS drive circuit 13; the input end of the forced cut-off control circuit 12 is connected to the third input end of the MOS; the first output end of the MOS drive circuit is connected to the first input end of the forced cut-off control circuit 14, and the second output end is connected to the second input end of the forced cut-off control circuit 14.

[0019] Specifically, the MOS driving circuit 13 includes a first driving circuit 131 and a second driving circuit 132; the forced cut-off control circuit 14 includes a first power supply circuit 141 and a second power supply circuit 142. The first input end of the MOS driving circuit 13 is set to correspond to the input end of the first driving circuit 131, the second input end is set to correspond to the first input end of the second driving circuit 132, and the third input end is set to correspond to the second input end of the second driving circuit 132; the first output end of the MOS driving circuit 13 is set to correspond to the output end of the first driving circuit 131, and the second output end is set to correspond to the output end of the second driving circuit 132.

[0020] The software interlock control circuit 11 has a first output end connected to the input end of the first drive circuit 131 , and a second output end connected to the first input end of the second drive circuit 132 .

[0021] The output end of the forced cut-off control circuit 12 is connected to the second input end of the second driving circuit 132 .

[0022] The output end of the first driving circuit 131 is connected to the input end of the first power supply circuit 141 , and the output end of the second driving circuit 132 is connected to the input end of the second power supply circuit 142 .

[0023] The software interlock control circuit 11 is used to ensure that at the same time (such as when one working mode has been started), another working mode is prevented from being started by mistake, thereby realizing the interlock between two or more working modes; and outputs corresponding control signals to the MOS drive circuit 13 through the first output terminal and the second output terminal respectively, so as to drive the MOS drive circuit 13 based on the current interlock state. The software interlock control circuit 11 ensures that only one output enable is valid at the same time, that is, only one power supply can be output, so as to improve the situation that when the microprocessor fails or two enables are turned on at the same time, no power supply will be output, thereby improving the system safety.

[0024] The forced cut-off control circuit 12 is used to immediately cut off the current when the system is abnormal (such as the system detects an abnormality or failure) to protect the system from further damage; the input end is connected to the third input end of the MOS drive circuit 13 to receive an emergency cut-off signal or instruction from other parts of the system (the specific working principle will be described in detail below).

[0025] The MOS driving circuit 13 is used to receive control signals from the software interlock control circuit 11 and / or the forced cut-off control circuit 12, and drive the MOS tube based on these signals; and control the direction and state of the current through the first output terminal and the second output terminal to control the operation of the dual power switching circuit 14.

[0026] The dual-power switching circuit 14 is used to switch the current from one power source or path to another power source or path in response to the control signal of the MOS driving circuit 13. In the path selection in this embodiment, in the application of transport refrigeration automobile air conditioner, it may be responsible for switching the current between the road mode (used when the car is running) and the standby mode (used when the car is stopped).

[0027] See also Figure 2 , is a schematic diagram of the circuit structure of a current switching circuit in an embodiment of the utility model.

[0028] Specifically, the software interlock control circuit 11 includes: a first enable port Vbat EN, a second enable port AUX_EN, resistors R14, RI5, R17, R18, logic circuits U1A, U1B, U2C, U2D and a ground terminal GND.

[0029] The first enable port Vbat EN is used to receive a power enable signal in an open path mode of the microprocessor;

[0030] A second enable port AUX_EN is used to receive a DC power enable signal of the microprocessor in the on-standby mode;

[0031] Resistors R14, RI5, R17, R18: used for current limiting, voltage division and filtering functions in the circuit;

[0032] Capacitors C1 and C2: connected in series with resistors R14 and R17 to form a filter circuit to eliminate noise and ripple in the power supply signal;

[0033] Logic circuits U1A, U1B, U2C, and U2D form an interlocking logic control circuit that determines the power output based on the signal states of the two enable ports.

[0034] Ground terminal GND: serves as the common reference point of the circuit.

[0035] The logical relationship of the software interlock control circuit 11 is as follows:

[0036] Bat_EN=1, AUX_EN=0: When the main power enable signal is valid (1) and the standby power enable signal is invalid (0), the main power Bat is output.

[0037] Bat_EN=0, AUX_EN=1: When the main power enable signal is invalid (0) and the standby power enable signal is valid (1), the standby power DC_AUX is output.

[0038] Bat_EN=1, AUX_EN=1 or Bat_EN=0, AUX_EN=0: When both enable signals are 1 or 0 at the same time, the circuit does not output any power. This design is to prevent the two power supplies from being turned on at the same time, which may cause power conflicts or damage the device.

[0039] The forced cut-off control circuit 12 includes: a key switch SW1, resistors R30, R31, R32, R34, a capacitor C3 and a logic circuit U2A. When the entire system is abnormal for some reason and the control mechanism inside the system cannot work normally, resulting in the power supply being unable to be shut down normally, manual intervention is necessary. In this case, the operator can press the key switch SW1. When SW1 is pressed, a trigger signal will be generated to the input end of the logic circuit U2A through a series of resistors (R30, R31, R32, R34) and a circuit connection of capacitor C3. The logic circuit U2A performs logical judgment based on the received trigger signal and outputs a control signal. This control signal will directly act on the power control circuit, usually controlling the output end of Vbat or DC_AUX power supply. When the logic circuit U2A outputs the corresponding control signal, the power control circuit will respond to this signal, thereby shutting down the output of Vbat or DC_AUX power supply.

[0040] Through this manual forced cut-off method, even if the control mechanism inside the system fails, it can ensure that the power supply can be safely shut down, thus avoiding possible equipment damage or safety risks. This design greatly improves the reliability and safety of the system.

[0041] The MOS driving circuit 13 includes: a MOS first driving circuit 131 for the main power supply Vbat and a MOS second driving circuit 132 for the standby power supply DC_AUX.

[0042] The MOS first driving circuit 131 of the road power supply Vbat includes: a logic circuit U1C, resistors R1, R8, R11, R12, R13, transistors Q1, Q4, Q7, a diode D1, and a voltage regulator diode DZ1;

[0043] The MOS second driving circuit 132 for the standby power supply DC_AUX includes: a logic circuit U1D, resistors R16, R25, R28, R29, R33, transistors Q8, Q11, Q14, a diode D2, and a voltage regulator diode DZ2.

[0044] The MOS first driving circuit 131 of the road power supply Vbat is used to drive the MOS tube of the road power supply Vbat to control its opening or closing. Specifically, through the switching characteristics of the transistors Q1, Q4, and Q7, combined with the resistors R1, R8, R11, R12, and R13 for current limiting and voltage division, and the diode D1 and the voltage regulator diode DZ1 for protection, the fast switching control of the MOS tube is realized.

[0045] The second MOS driving circuit 132 for the standby power supply DC_AUX is used to drive the MOS tube of the standby power supply DC_AUX to control its on or off. Similar to the first MOS driving circuit 131, through the switching characteristics of the transistors Q8, Q11, and Q14, combined with the resistors R16, R25, R28, R29, and R33 for current limiting and voltage division, and the diode D2 and the voltage regulator diode DZ2 for protection, the fast switching control of the MOS tube is realized.

[0046] The dual power switching circuit 14 is used to determine whether to turn on the main power supply Vbat or the standby power supply DC_AUX, or turn off both, according to the circuit control signal of the front end, so as to connect the selected power supply to the system total power supply PWR_OUT.

[0047] Specifically, the first power supply circuit 141, that is, the road power supply Vbat circuit, includes: MOS tubes Q2, Q3, Q15, Q5, Q6, Q16, and gate voltage divider resistors R2, R3, R4, R5, R36, R35, R9, R6, R10, R7, R37, and R38.

[0048] As a switching element, the MOS tube controls its gate voltage according to the state of the control signal (such as the signal from the software interlock control circuit 11 or the forced cut-off control circuit 12), thereby controlling the on or off of the MOS tube. The gate voltage divider resistor is used to adjust the voltage of the MOS tube gate to ensure that the MOS tube can operate within the correct voltage range to avoid overvoltage or undervoltage damage. When the road power supply Vbat (first power supply circuit 141) needs to be connected to the system main power supply PWR_OUT, the corresponding MOS tube is controlled to be in the on state, so that Vbat can flow into PWR_OUT.

[0049] The second power supply circuit 142, that is, the standby power supply DC_AUX circuit, includes: MOS tubes Q9, Q10, Q17, Q12, Q13, Q18, and gate voltage dividing resistors R19, R20, R22, R21, R40, R39, R26, R23, R27, R24, R42, and R41.

[0050] Similar to the main power supply Vbat circuit (first power supply circuit 141), the MOS tube in the standby power supply DC_AUX circuit (second power supply circuit 142) is also controlled to be turned on or off according to the state of the control signal. The function of the gate voltage divider resistor is also to adjust the voltage of the MOS tube gate to ensure that the MOS tube operates within an appropriate voltage range. When the standby power supply DC_AUX needs to be connected to the system main power supply PWR_OUT, the corresponding MOS tube is controlled to be in the on state, so that DC_AUX can flow into PWR_OUT.

[0051] In this way, the software interlock control circuit 11 receives the Vbat EN and AUX_EN signals sent by the microprocessor, and uses the logical relationship of the logic circuits U1A, U1B, U2C, and U2D to generate corresponding control signals according to the signal states of Vbat EN and AUX_EN. The control signals act on the MOS drive circuit 13 to control the corresponding MOS tube to be turned on or off, thereby selectively outputting the road power Vbat or the standby power DC_AUX to the system total power PWR_OUT.

[0052] When an abnormality occurs in the system, the forced cut-off control circuit 12 is manually operated (pressing the button SW1) to generate a trigger signal through the circuit connection of the resistor and the capacitor, and the trigger signal is sent to the logic circuit U2A; the logic circuit U2A outputs a control signal according to the trigger signal to control the MOS tube in the MOS driving circuit 13 to turn off, thereby cutting off all power outputs to the system main power supply PWR_OUT and forcibly cutting off all power outputs to ensure system safety.

[0053] The dual power switching circuit 14 realizes switching control of the road power Vbat and the standby power DC_AUX according to the control signal of the software interlock control circuit 11, ensuring the stable power supply of the system total power PWR_OUT. Combined with the software interlock control circuit 11 and the forced cut-off control circuit 12, the reliability and safety of the system are improved.

[0054] The MOS driving circuit 13 drives the MOS tube to turn on or off the power quickly and accurately according to the control signals of the software interlocking control circuit 11 and the forced cut-off control circuit 12. As an important component of the dual power switching circuit 14, the rapidity and accuracy of the power switching are ensured.

[0055] The entire system realizes intelligent switching of the road power supply Vbat and the standby power supply DC_AUX through the software interlock control circuit 11, and provides an emergency cut-off function in combination with the forced cut-off control circuit 12, thereby ensuring the reliability and safety of the system. The MOS drive circuit 13, as an actuator, is responsible for quickly and accurately driving the MOS tube to turn on or off the power supply according to the control signal, thereby realizing a stable power supply to the system total power supply PWR_OUT.

[0056] The current switching circuit of the utility model is optimized for high current switching and has better stability and reliability. Compared with the traditional relay solution, the utility model can handle high current switching more effectively, reducing the shortened life of the relay due to frequent operation and potential safety problems; the circuit has built-in protection mechanisms against backflow and reverse connection, which effectively avoids the reverse flow of current due to incorrect power connection or abnormal conditions, further improving the safety and stability of the system; through software interlock protection, the circuit ensures that only one power supply can be output at any time, avoiding the problem of simultaneous output of multiple power supplies due to misoperation or system failure. At the same time, when the microcontroller (MCU) fails, the circuit can automatically shut down the output, effectively protecting the safety of the system; the circuit is also equipped with a forced cut-off protection function. When the system is abnormal, the power output can be quickly cut off through manual external operation, so as to respond in time and avoid possible damage or danger; this solution can adapt to power supply requirements of different powers, making the circuit more flexible and versatile, and can be widely used in various occasions requiring current switching; compared with traditional relay solutions, this solution is also more cost-effective, not only can it reduce hardware costs, but also can reduce maintenance and replacement costs caused by system failures by improving system stability and reliability.

[0057] The above description is only an embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the specification and drawings of the present invention, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A current switching circuit, characterized in that: include: Software interlock control circuit, forced cut-off control circuit, MOS drive circuit, dual power supply switching circuit; The first output terminal of the software interlock control circuit is connected to the first input terminal of the MOS drive circuit, and the second output terminal is connected to the second input terminal of the MOS drive circuit; The input end of the forced cut-off control circuit is connected to the third input end of the MOS; the first output end of the MOS drive circuit is connected to the first input end of the forced cut-off control circuit, and the second output end is connected to the second input end of the forced cut-off control circuit; The MOS driving circuit includes a first driving circuit and a second driving circuit; the forced cut-off control circuit includes a first power supply circuit and a second power supply circuit; wherein the first input end of the MOS driving circuit is set corresponding to the input end of the first driving circuit, the second input end is set corresponding to the first input end of the second driving circuit, and the third input end is set corresponding to the second input end of the second driving circuit; the first output end of the MOS driving circuit is set corresponding to the output end of the first driving circuit, and the second output end is set corresponding to the output end of the second driving circuit.

2. A current switching circuit according to claim 1, characterized in that: The software interlock control circuit includes: a first enable port Vbat EN, a second enable port AUX_EN, resistors R14, RI5, R17, R18, logic circuits U1A, U1B, U2C, U2D and a ground terminal GND; The first enable port Vbat EN is used to receive a power enable signal in an open path mode of the microprocessor; A second enable port AUX_EN is used to receive a DC power enable signal of the microprocessor in the on-standby mode; Resistors R14, RI5, R17, R18: used for current limiting, voltage division and filtering functions in the circuit; Capacitors C1 and C2: connected in series with resistors R14 and R17 to form a filter circuit to eliminate noise and ripple in the power supply signal; Logic circuits U1A, U1B, U2C, and U2D: form an interlocking logic control circuit to determine the power output according to the signal status of the two enable ports; Ground terminal GND: serves as the common reference point of the circuit.

3. A current switching circuit according to claim 2, characterized in that: The MOS driving circuit comprises: a MOS first driving circuit for the main power supply Vbat and a MOS second driving circuit for the standby power supply DC_AUX; The MOS first driving circuit of the road power supply Vbat includes: a logic circuit U1C, resistors R1, R8, R11, R12, R13, transistors Q1, Q4, Q7, a diode D1, and a voltage regulator diode DZ1; The MOS second driving circuit for the standby power supply DC_AUX includes: a logic circuit U1D, resistors R16, R25, R28, R29, R33, transistors Q8, Q11, Q14, a diode D2, and a voltage regulator diode DZ2.

4. A current switching circuit according to claim 3, characterized in that: The first power supply circuit includes: MOS tubes Q2, Q3, Q15, Q5, Q6, Q16, gate voltage dividing resistors R2, R3, R4, R5, R36, R35, R9, R6, R10, R7, R37, R38; The second power supply circuit includes: MOS tubes Q9, Q10, Q17, Q12, Q13, Q18, and gate voltage dividing resistors R19, R20, R22, R21, R40, R39, R26, R23, R27, R24, R42, and R41.

5. The current switching circuit according to claim 1, characterized in that: The forced cut-off control circuit includes: a key switch SW1, resistors R30, R31, R32, R34, a capacitor C3 and a logic circuit U2A.

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