A control circuit for the air-cooled cooling fan of a new energy vehicle-mounted DCDC module

Abstract

The present invention discloses a control circuit for a new energy vehicle-mounted DCDC module air-cooled heat dissipation fan, including a current sampling circuit, which is used to output a Hall level of corresponding magnitude according to the magnitude of the current flowing through the high-voltage positive line of the DCDC module; a current judgment circuit, which is used to obtain the Hall level and output a fan control signal after comparing it with a reference level; and a fan control circuit, which is used to obtain the fan control signal to control the start and stop of the fan. The present invention realizes the function of real-time judgment of the working power of the module through the current sampling circuit and the current judgment circuit, so as to achieve the purpose of controlling the fan to start and stop according to the working power of the module and the heating condition.

Description

Technical Field

[0001] The present invention relates to the technical field of DCDC module heat dissipation, and in particular to a control circuit for an air-cooled heat dissipation fan of a new energy vehicle-mounted DCDC module. Background Art

[0002] For electric vehicles, the direct current-direct current converter (hereinafter referred to as "DCDC") is one of the most important power supply devices, usually used to power electronic devices on the vehicle that use 12V or 24V auxiliary power, and to charge the battery on the vehicle. The DCDC modules on new energy vehicles are mostly integrated into the four-in-one or five-in-one motor drivers, and the water cooling system of the motor driver is used to dissipate the heat of the module. Therefore, conventional DCDC products do not have a cooling fan control design reserved for air cooling.

[0003] For the DCDC air-cooled cooling fan control solution currently on the market, the cooling fan is directly connected in parallel to the positive and negative poles of the DCDC output terminal. As long as the voltage on the positive and negative lines of the DCDC reaches the working requirements of the cooling fan, the fan will work. The positive and negative poles of the DCDC output are usually directly connected to the vehicle battery, and there is no other control switch on the line. Therefore, the traditional air-cooled cooling solution is equivalent to directly connecting the cooling fan in parallel to the vehicle battery, which leads to the problem of the vehicle battery running low due to the continuous operation of the cooling fan. Summary of the invention

[0004] The object of the present invention is to provide a control circuit for an air-cooled heat dissipation fan of a DCDC module on a new energy vehicle.

[0005] To achieve the above object, the present invention provides the following technical solution: a control circuit for an air-cooled heat dissipation fan of a DCDC module on a new energy vehicle, comprising:

[0006] The current sampling circuit is used to output a Hall level of corresponding magnitude according to the magnitude of the current flowing through the high-voltage positive line of the DCDC module;

[0007] A current determination circuit, used for obtaining the Hall level and comparing it with a reference level to output a fan control signal; and

[0008] The fan control circuit is used to obtain the fan control signal to control the start and stop of the fan.

[0009] Furthermore, it also includes a voltage-stabilized power supply circuit, which is used to stabilize the power supply and supply power to the current sampling circuit, the current judgment circuit, and the fan control circuit.

[0010] Furthermore, the voltage-stabilized power supply circuit includes resistors R1, R2, R37, R38, R40, and R41, capacitors C28, C32, C6, and C3, a transistor Q5, and a three-terminal adjustable parallel regulator U5. The resistors R37 and R38 are connected in parallel and connected to the collector of the transistor Q5. The base of the transistor Q5 is connected to pin 1 of the three-terminal adjustable parallel regulator U5 through a resistor R41. One end of the resistor R40 is connected between the resistor R41 and pin 1 of the three-terminal adjustable parallel regulator U5. The other end of the resistor R40 is connected to the parallel capacitors C28 and C32, and the capacitors C28 and C32 are connected in parallel to the parallel resistors R37 and R38. The resistors R1 and R2 are connected in series in sequence, and the other end of the resistor R1 is connected to the emitter of the transistor Q5. One end of the resistor R2 is connected to the 3rd pin of the three-terminal adjustable parallel regulator U5, and the 2nd pin of the three-terminal adjustable parallel regulator U5 is connected between the resistors R1 and R2. The capacitors C6 and C3 are connected in parallel to the resistor R1 and the transistor Q5.

[0011] Furthermore, the current sampling circuit includes input terminals J1 and J2 and a current sensor L1 , wherein the input terminal J1 is connected to the positive input terminal of the current sensor L1 , and the input terminal J2 is connected to the negative input terminal of the current sensor L1 .

[0012] Furthermore, the current judgment circuit includes a comparator U6, resistors R3, R4, R5, R8, R10, capacitors C1, C2, and C8, the positive phase input terminal of the comparator U6 is connected to one end of the resistor R4, one end of the capacitor C1 is connected between the comparator U6 and the resistor R4, the resistor R10 is connected to the positive phase input terminal and the output terminal of the comparator U6 and then connected to the resistor R8, one end of the capacitor C8 is connected to the resistor R8, and the other end of the capacitor C8 is grounded, the negative phase input terminal of the comparator U6 is connected to one end of the resistor R5, and the resistor R3 is connected in parallel with the capacitor C2 and then connected between the comparator U6 and the resistor R5.

[0013] Further, the fan control circuit includes resistors R6, R7, R9, and R11, capacitors C4, C5, and C7, a transistor Q2, and a MOS transistor Q6. One end of the resistor R6 is connected to the base of the transistor Q2, one end of the resistor R7 and the capacitor C4 are both connected between the resistor R6 and the transistor Q2, and the other ends of the resistor R7 and the capacitor C4 are connected to the emitter of the transistor Q2. The resistor R7 and the capacitor C4 are connected in parallel, the collector of the transistor Q2 is connected to the gate of the MOS transistor Q6 through the resistor R11, one end of the capacitor C5 is connected to the source of the MOS transistor Q6, one end of the resistor R9 is connected between the resistor R11 and the MOS transistor Q6, the other end of the resistor R9 is connected between the capacitor C5 and the MOS transistor Q6, and the capacitor C7 is connected between the drain of the MOS transistor Q6 and the emitter of the transistor Q2.

[0014] Furthermore, the MOS transistor Q6 is a P-channel MOS transistor.

[0015] Furthermore, the model of the three-terminal adjustable shunt regulator U5 is LM431.

[0016] It can be seen from the above technical solution that the present invention has the following beneficial effects:

[0017] The control circuit of the air-cooled heat dissipation fan of the DCDC module on the new energy vehicle realizes the function of real-time judgment of the module working power through the current sampling circuit and the current judgment circuit, so as to achieve the purpose of controlling the fan to be turned on and off according to the module working power and heating conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a circuit diagram of a voltage-stabilized power supply of the present invention;

[0019] Figure 2 This is a current sampling circuit diagram of the present invention;

[0020] Figure 3 This is a current determination circuit diagram of the present invention;

[0021] Figure 4 The fan control circuit diagram of the present invention;

[0022] Figure 5 This is the basic operation logic circuit diagram of current judgment of the present invention. DETAILED DESCRIPTION

[0023] In the description of the present invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "two ends", "one end", "the other end" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0024] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", etc. should be understood in a broad sense. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] See also Figure 1-2 The present invention provides a control circuit for a new energy vehicle-mounted DCDC module air-cooled heat dissipation fan, including a current sampling circuit, a current judgment circuit, a fan control circuit and a voltage-stabilized power supply circuit. Figure 1 As shown, the voltage-stabilized power supply circuit includes resistors R1, R2, R37, R38, R40, and R41, capacitors C28, C32, C6, and C3, a transistor Q5, and a three-terminal adjustable parallel regulator U5. The resistors R37 and R38 are connected in parallel and connected to the collector of the transistor Q5. The base of the transistor Q5 is connected to pin 1 of the three-terminal adjustable parallel regulator U5 through a resistor R41. One end of the resistor R40 is connected between the resistor R41 and pin 1 of the three-terminal adjustable parallel regulator U5. The other end of the resistor R40 is connected to the collector of the three-terminal adjustable parallel regulator U5. The capacitors C28 and C32 are connected in parallel, and the capacitors C28 and C32 are connected in parallel to the resistors R37 and R38. The resistors R1 and R2 are connected in series in sequence, and the other end of the resistor R1 is connected to the emitter of the transistor Q5. One end of the resistor R2 is connected to the 3rd pin of the three-terminal adjustable parallel regulator U5, and the 2nd pin of the three-terminal adjustable parallel regulator U5 is connected between the resistors R1 and R2. The capacitors C6 and C3 are connected in parallel to the resistor R1 and the transistor Q5. The model of the three-terminal adjustable parallel regulator U5 is LM431.

[0027] When the voltage-stabilized power supply circuit starts working, first, the +24V power supply will control Q5 to conduct through R40 and R41 to charge the capacitors C6 and C3 at the back end. At this time, the output voltage of the voltage-stabilized power supply circuit is less than 5V, and the voltage obtained by R1 and R2 on the reference voltage pin of the three-terminal adjustable parallel regulator U5 is also less than 2.5V, so the cathode and anode of the three-terminal adjustable parallel regulator U5 are in an open circuit state. When the voltage across the capacitor (i.e., the output voltage of the voltage-stabilized power supply circuit) is charged to a state greater than 5V, the voltage obtained by R1 and R2 on the reference voltage pin of the three-terminal adjustable parallel regulator U5 will be greater than 2.5V. At this time, the anode and cathode of the three-terminal adjustable parallel regulator U5 are in a conducting state, which is equivalent to grounding the base of the transistor Q5, thereby controlling Q5 to turn off. After Q5 is turned off, the back-end load (i.e., the current sampling circuit, the current judgment circuit, and the fan control circuit) is powered by C3 and C6. When the back-end When the load consumes the voltage across the capacitor to below 5V, the voltage divided on the reference voltage pin of LM431 will be less than 2.5V again. At this time, the anode and cathode of the three-terminal adjustable shunt regulator U5 will be restored to the open circuit state, and the +24V power supply will control Q5 to conduct through R40 and R41 to charge the capacitors C6 and C3 at the back end, thereby dynamically adjusting the output voltage of the voltage-stabilized power supply circuit and stabilizing the output voltage at 5V, and then powering the current sampling circuit, current judgment circuit, and fan control circuit.

[0028] Among them, R37 and R38 play a current limiting role. When the rear-end load of the voltage-stabilized power supply circuit is short-circuited, the current loop can be cut off to protect other components in the circuit from being damaged by large current. R40 and R41 are used to provide the minimum operating current required by the base of the transistor Q5 when it is saturated and turned on. In addition, it also ensures that the cathode current of the three-terminal adjustable parallel regulator U5 is greater than 1mA when it works normally. The role of R1 and R2 is to divide the output voltage of this voltage-stabilized power supply circuit and feed it back to the reference voltage pin of the three-terminal adjustable parallel regulator U5. The three-terminal adjustable parallel regulator U5 compares the voltage obtained on the reference voltage pin with the internal reference source, and then dynamically adjusts the conduction and shutdown states between its anode and cathode to achieve the purpose of adjusting the output voltage of the entire voltage-stabilized power supply circuit. C28, C32, C6, and C3 play the role of energy storage, filtering, and voltage stabilization.

[0029] like Figure 2 As shown, the current sampling circuit includes input terminals J1, J2 and a current sensor L1, wherein the input terminal J1 is connected to the positive input terminal of the current sensor L1, and the input terminal J2 is connected to the negative input terminal of the current sensor L1;

[0030] When the current sampling circuit is working normally, the primary side of the current sensor L1 is connected in series to the high-voltage power supply circuit of the DCDC module through J1 and J2. Based on the Hall effect principle, a Hall potential will be generated between the working current perpendicular to the high-voltage input port and the direction of the Hall internal magnetic field. The magnitude of the Hall potential is proportional to the magnitude of the high-voltage input current. This circuit is in working state after power-on. The working logic of the strong power side is mainly as follows: the positive pole of the high-voltage electricity supplied to the DCDC module is first connected to HV+IN (i.e. the +IN pin of the current sensor), and then connected to the positive pole of the high-voltage input of the DCDC module by HV+OUT (i.e. the -IN pin of the current sensor) after flowing through the current sensor L1. At this time, as long as a 5V power supply is connected to the +5V input pin on the weak-current side of the current sensor L1 to ensure that L1 is powered on and in normal working state, the L1 output pin (OUT) can output the corresponding Hall voltage level according to the magnitude of the current flowing through the high-voltage positive line of the DCDC module.

[0031] like Figure 3 As shown, the current judgment circuit includes a comparator U6, resistors R3, R4, R5, R8, R10, capacitors C1, C2, C8, the positive phase input terminal of the comparator U6 is connected to one end of the resistor R4, one end of the capacitor C1 is connected between the comparator U6 and the resistor R4, the resistor R10 is connected to the positive phase input terminal and the output terminal of the comparator U6 and then connected to the resistor R8, one end of the capacitor C8 is connected to the resistor R8, and the other end of the capacitor C8 is grounded, the negative phase input terminal of the comparator U6 is connected to one end of the resistor R5, and the resistor R3 is connected in parallel with the capacitor C2 and then connected between the comparator U6 and the resistor R5;

[0032] Comparator U6 compares the reference level and the Hall output level to determine whether the current module operating power is higher than the threshold, thereby outputting the fan control signal. In addition, comparator U6 uses a hysteresis comparator. The hysteresis comparator has a higher anti-interference ability, which avoids the risk of damage to the fan caused by repeated start and stop of the cooling fan in a short period of time. Resistors R4 and R10 are used to set the upper and lower flip points and hysteresis of the hysteresis comparator, resistors R5, R3 and 5VCC input are used to set the comparison reference level, resistor R8 is used for pull-up, capacitors C1 and C2 are used for filtering, and capacitor C8 is used to decouple the 5V power supply of comparator U6;

[0033] Assume that the comparison reference level set by the voltage divider resistors R3, R5 and 5VCC input is V - , then V - =5*R3 / (R3+R4);

[0034] When the level at the non-inverting input of comparator U6 is less than V - When the comparator U6 output level is low impedance, it is assumed that the upper limit trigger level of U6 is V 上 , then through the formula (V上 -V - ) / R4=(V - -0) / R10 to get V 上 =(1+R4 / R10)*V - ;

[0035] When the level at the non-inverting input of comparator U6 is greater than V - When the comparator U6 output level is high impedance, it is assumed that the comparator U6 lower limit trigger level is V 下 , then by the formula (5-V - ) / R10=(V - -V 下 ) / R4 can get V 下 =(1+R4 / R10)*V - -5*R4 / R10;

[0036] The basic operation logic of this circuit is as follows Figure 5 As shown, when the Hall potential output by the current sensor L1 is the level of the non-inverting input terminal of the comparator U6 of this circuit (hereinafter referred to as V hall out ) is less than V 上 When the comparator U6 output is 0V; when V hall out Greater than V 上 After that, the output of comparator U6 turns up to 5V. hall out Reduced and less than V 下 The comparator output then rolls down to 0V.

[0037] like Figure 4 As shown, the fan control circuit includes resistors R6, R7, R9, and R11, capacitors C4, C5, and C7, a transistor Q2, and a MOS transistor Q6. One end of the resistor R6 is connected to the base of the transistor Q2. One end of the resistor R7 and the capacitor C4 are both connected between the resistor R6 and the transistor Q2. The other ends of the resistor R7 and the capacitor C4 are connected to the emitter of the transistor Q2. The resistor R7 and the capacitor C4 are connected in parallel. The collector of the transistor Q2 is connected to the gate of the MOS transistor Q6 through the resistor R11. One end of the capacitor C5 is connected to the source of the MOS transistor Q6. One end of the resistor R9 is connected between the resistor R11 and the MOS transistor Q6. The other end of the resistor R9 is connected between the capacitor C5 and the MOS transistor Q6. The capacitor C7 is connected between the drain of the MOS transistor Q6 and the emitter of the transistor Q2. The MOS transistor Q6 is a P-channel MOS transistor.

[0038] C7 plays a role of voltage stabilization. Selecting a capacitor with a larger capacity can stabilize the output voltage of this fan control circuit. C4 and C5 play a role of filtering. Selecting a capacitor with a smaller capacitance can stabilize the output voltage of this fan control circuit.

[0039] From the perspective of input-output relationship, this circuit is mainly divided into three parts: control signal input, power flow input, and power flow output. The control signal is given by the high-voltage port input current judgment circuit and transmitted to pin 2 of resistor R6. When the input received by R6 is low level, transistor Q2 is not turned on, and the base of Q6 is a high level obtained by voltage division by R9, so as to ensure that Q6 is not turned on under normal conditions, the +24V power supply cannot be transmitted to FAN+, and the fan does not start; when R6 receives a high level, it can drive transistor Q2 to turn on after voltage division by R6 and R7. The conduction of Q2 is equivalent to pulling the base of MOS tube Q6 from high level to low level, so that Q6 is turned on, and the +24V power supply can flow to the FAN+ output terminal to drive the fan to rotate.

[0040] After the DCDC module is powered on, the overall circuit of this solution has entered the working state, but before the high-voltage input current reaches the design threshold, the fan is in standby mode. The cooling fan will not start until the high-voltage input current reaches the design threshold, that is, when the current operating power of the DCDC module reaches the standard that requires the fan to assist in cooling.

[0041] The present invention realizes the function of real-time judgment of module working power through current sampling circuit and current judgment circuit, so as to achieve the purpose of controlling the fan to be turned on and off according to the module working power and heating condition.

[0042] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A control circuit for the air-cooled cooling fan of a new energy vehicle DCDC module. It is characterized in that include: The current sampling circuit is used to output a Hall level of corresponding magnitude according to the magnitude of the current flowing through the high-voltage positive line of the DCDC module; A current judgment circuit is used to obtain the Hall level and compare it with the reference level to output a fan control signal; as well as A fan control circuit is used to obtain a fan control signal to control the start and stop of the fan; The current sampling circuit includes input terminals J1, J2 and a current sensor L1, wherein the input terminal J1 is connected to the positive input terminal of the current sensor L1, and the input terminal J2 is connected to the negative input terminal of the current sensor L1; The current judgment circuit includes a comparator U6, resistors R3, R4, R5, R8, R10, capacitors C1, C2, C8, the positive phase input terminal of the comparator U6 is connected to one end of the resistor R4, one end of the capacitor C1 is connected between the comparator U6 and the resistor R4, the resistor R10 is connected to the positive phase input terminal and the output terminal of the comparator U6 and then connected to the resistor R8, one end of the capacitor C8 is connected to the resistor R8, and the other end of the capacitor C8 is grounded, the negative phase input terminal of the comparator U6 is connected to one end of the resistor R5, and the resistor R3 is connected in parallel with the capacitor C2 and then connected between the comparator U6 and the resistor R5; The fan control circuit includes resistors R6, R7, R9, and R11, capacitors C4, C5, and C7, a transistor Q2, and a MOS transistor Q6. One end of the resistor R6 is connected to the base of the transistor Q2, one end of the resistor R7 and one end of the capacitor C4 are both connected between the resistor R6 and the transistor Q2, and the other ends of the resistor R7 and the capacitor C4 are connected to the emitter of the transistor Q2. The resistor R7 and the capacitor C4 are connected in parallel, the collector of the transistor Q2 is connected to the gate of the MOS transistor Q6 through the resistor R11, one end of the capacitor C5 is connected to the source of the MOS transistor Q6, one end of the resistor R9 is connected between the resistor R11 and the MOS transistor Q6, the other end of the resistor R9 is connected between the capacitor C5 and the MOS transistor Q6, and the capacitor C7 is connected between the drain of the MOS transistor Q6 and the emitter of the transistor Q2.

2. According to claim 1, a control circuit for an air-cooled heat dissipation fan of a new energy vehicle-mounted DCDC module, Features: It also includes a voltage-stabilized power supply circuit, which is used to stabilize the power supply and supply power to the current sampling circuit, the current judgment circuit, and the fan control circuit.

3. According to claim 2, a control circuit for an air-cooled heat dissipation fan of a new energy vehicle-mounted DCDC module, Features: The voltage-stabilized power supply circuit includes resistors R1, R2, R37, R38, R40, and R41, capacitors C28, C32, C6, and C3, a transistor Q5, and a three-terminal adjustable parallel regulator U5. The resistors R37 and R38 are connected in parallel and connected to the collector of the transistor Q5. The base of the transistor Q5 is connected to pin 1 of the three-terminal adjustable parallel regulator U5 through a resistor R41. One end of the resistor R40 is connected between the resistor R41 and pin 1 of the three-terminal adjustable parallel regulator U5. The other end of R40 is connected to capacitors C28 and C32 in parallel, and the capacitors C28 and C32 are connected in parallel to resistors R37 and R38. The resistors R1 and R2 are connected in series in sequence, and the other end of the resistor R1 is connected to the emitter of the transistor Q5. One end of the resistor R2 is connected to pin 3 of the three-terminal adjustable parallel regulator U5, and pin 2 of the three-terminal adjustable parallel regulator U5 is connected between the resistors R1 and R2. The capacitors C6 and C3 are connected in parallel to the resistor R1 and the transistor Q5.

4. According to claim 1, a control circuit for an air-cooled heat dissipation fan of a new energy vehicle-mounted DCDC module, Features: The MOS transistor Q6 is a P-channel MOS transistor.

5. According to claim 3, a control circuit for an air-cooled heat dissipation fan of a new energy vehicle-mounted DCDC module, Features: The model of the three-terminal adjustable shunt regulator U5 is LM431.

Images