Isolation type fan PWM control circuit based on small direct current charging pile

Abstract

The invention discloses an isolated fan PWM (Pulse Width Modulation) control circuit based on a small direct current charging pile, which belongs to the field of new energy and comprises a DSP (Digital Signal Processor) chip U1, a high-speed optocoupler U2 and a fan F1, the output end of the DSP chip U1 is connected with the base electrode of the triode Q1, the collector electrode of the triode Q1 is connected with the input cathode of the high-speed optical coupler U2, and the input anode of the high-speed optical coupler U2 is connected with a power supply PVCC; an output collector electrode of the high-speed optocoupler U2 is connected with one end of a resistor R1 and one end of a resistor R2 at the same time, and the other end of the resistor R2 is connected with a base electrode of a triode Q2; the collector electrode of the triode Q2 is connected with one end of the resistor R3, and the PWM speed regulation pin of the fan F1 is connected with the collector electrode of the triode Q2; and a PWM speed regulation pin of the fan F1 is in communication connection with the DSP chip U1. The fan is simple in structure, low in cost, high in performance and high in cost performance, loss caused by the fan is greatly reduced, and noise to the surrounding environment is reduced.

Description

Technical Field

[0001] The present invention relates to the field of new energy, and in particular to an isolated fan PWM control circuit based on a small DC charging pile. Background Art

[0002] With the increasing popularity of new energy electric vehicles, the demand for charging piles has also shown a rapid growth trend. It is expected that by 2025, the sales volume of new energy vehicles in my country will exceed the 2500W mark, which undoubtedly provides a huge market space for the construction of charging infrastructure. Among the many types of charging piles, small DC charging piles have great development potential. At present, the technology of small DC charging piles has achieved a breakthrough in marketization, especially in the application of residential areas, showing its advantages, which can streamline vehicle design, reduce costs, and meet the needs without upgrading the existing power grid. In addition, with the rapid growth of the new energy vehicle market, the demand for charging infrastructure is also increasing, which provides a broad market space for small DC charging piles. Small DC charging piles convert state grid AC power into DC power. There is a power conversion process, and heat energy loss will be generated in this power conversion process. Therefore, generally small DC charging piles are equipped with fans to dissipate heat for charging piles. For different ambient temperatures, the internal temperature rise and heat loss of the charging piles are different, so it is necessary to control the speed of the fan, and then set the most suitable speed according to the actual situation to reduce environmental noise and energy loss.

[0003] At present, the fan speed control of small DC charging piles on the market includes PWM control and other control methods. PWM controls the cooling fan, which is the current mainstream speed regulation method. It is widely used in various smart devices such as charging piles and car central control. By adjusting the duty cycle of the pulse signal, the fan speed can be accurately controlled to achieve efficient heat dissipation.

[0004] However, the existing PWM control uses a switching signal and is not isolated from the fan, so it will generate greater interference noise to the system; the resistor-controlled fan adjusts the fan speed by changing the resistance of an external resistor. Different resistance values ​​correspond to different speeds. This method is relatively simple but has low adjustment accuracy; the last is the constant-speed fan, which keeps the fan at a constant speed and can provide a stable heat dissipation effect, but will generate greater noise to the environment, and the fan's life will be greatly reduced if it runs at full speed for a long time, and it will also waste energy. Summary of the invention

[0005] With regard to the above-mentioned problems existing in the prior art, an object of the present invention is to provide an isolated fan PWM control circuit based on a small DC charging pile to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] An isolated fan PWM control circuit based on a small DC charging pile includes a DSP chip U1, a high-speed optocoupler U2, a transistor Q1, a transistor Q2, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a fan F1;

[0008] The output end of the DSP chip U1 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is grounded;

[0009] The collector of transistor Q1 is connected to the input cathode of high-speed optocoupler U2, and the input anode of high-speed optocoupler U2 is connected to the power supply PVCC;

[0010] The output collector of the high-speed optocoupler U2 is connected to one end of the resistor R1 and one end of the resistor R2 at the same time, the other end of the resistor R1 is connected to the power supply SVCC, and the other end of the resistor R2 is connected to the base of the transistor Q2;

[0011] The output emitter of the high-speed optocoupler U2 is grounded;

[0012] The collector of transistor Q2 is connected to one end of resistor R3, and the other end of resistor R3 is connected to power supply SVCC.

[0013] The emitter of transistor Q2 is grounded;

[0014] The PWM speed control pin of the fan F1 is connected to the collector of the transistor Q2; the GND terminal of the fan F1 is grounded, and the VCC terminal of the fan F1 is connected to the power supply SVCC;

[0015] The two ends of the resistor R4 are connected in parallel to the PWM speed control foot of the fan F1 and the GND end of the fan F1;

[0016] The PWM speed regulating foot of the fan F1 is connected to the DSP chip U1 for communication.

[0017] As a further solution of the present invention: the ground terminal to which the emitter of the transistor Q1 is connected is PGND.

[0018] As a further solution of the present invention: the ground terminal to which the output emitter of the high-speed optical coupler U2, the emitter of the transistor Q2, and the GND terminal of the fan F1 are connected is SGND.

[0019] As a further solution of the present invention: the high-speed optical coupler U2 is connected to the power supply SVCC.

[0020] As a further solution of the present invention: the DSP chip U1 is connected to a temperature sensor, and the temperature sensor is installed inside the charging pile.

[0021] As a further solution of the present invention: the DSP chip U1 is provided with a data processing unit and a database.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Without significantly changing the circuit, the present invention realizes the fan PWM speed control function of the small DC charging pile in a simple, low-cost, high-performance, and cost-effective form, greatly reduces the loss caused by the fan, reduces the noise to the surrounding environment, has high speed control accuracy, can achieve stepless speed regulation, and the adopted isolation control scheme can effectively reduce EMC, is relatively friendly to the EMC design of the charging pile, and can greatly reduce the interference noise to other circuits in the pile; the invention of this design can solve the current market pain points of backward speed control, high noise, and high interference of the fan of small DC charging piles, can be well adapted to various types of charging piles, is safe, stable, reliable, and has high compatibility, and will not affect the performance parameters of the charging pile, and solves the current problems of low speed control accuracy and high interference noise of the fan of small DC charging piles. The key point is to use high-speed optocouplers to isolate PWM waves, greatly reduce the interference of the fan to the system, and the speed of the fan can be adjusted by adjusting the duty cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a schematic diagram of the circuit structure of an isolated fan PWM control circuit based on a small DC charging pile disclosed in an embodiment. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention; it is obvious that 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] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "provided with", "connected", and "connected" should be understood in a broad sense; for example, it can be a fixed connection, a detachable connection, or an integral connection, a mechanical connection, or an electrical connection, a direct connection, or an indirect connection through an intermediate medium, or 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.

[0027] See also Figure 1, an isolated fan PWM control circuit based on a small DC charging pile, including a DSP chip U1, a high-speed optocoupler U2, a transistor Q1, a transistor Q2, a resistor R1, a resistor R2, a resistor R3, a resistor R4 and a fan F1;

[0028] The output end of the DSP chip U1 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is grounded;

[0029] The collector of transistor Q1 is connected to the input cathode of high-speed optocoupler U2, and the input anode of high-speed optocoupler U2 is connected to the power supply PVCC;

[0030] The output collector of the high-speed optocoupler U2 is connected to one end of the resistor R1 and one end of the resistor R2 at the same time, the other end of the resistor R1 is connected to the power supply SVCC, and the other end of the resistor R2 is connected to the base of the transistor Q2;

[0031] The output emitter of the high-speed optocoupler U2 is grounded;

[0032] The collector of transistor Q2 is connected to one end of resistor R3, and the other end of resistor R3 is connected to power supply SVCC.

[0033] The emitter of transistor Q2 is grounded;

[0034] The PWM speed control pin of the fan F1 is connected to the collector of the transistor Q2; the GND terminal of the fan F1 is grounded, and the VCC terminal of the fan F1 is connected to the power supply SVCC;

[0035] The two ends of the resistor R4 are connected in parallel to the PWM speed control foot of the fan F1 and the GND end of the fan F1;

[0036] The PWM speed regulating foot of the fan F1 is connected to the DSP chip U1 for communication;

[0037] The high-speed optocoupler U2 is connected to the power supply SVCC;

[0038] The DSP chip U1 is connected to the temperature sensor, which is installed inside the charging pile. The temperature of the charging pile can be measured at any time during operation through the temperature sensor, and the data can be transmitted to the DSP chip U1 for processing, which is convenient for subsequent use.

[0039] The DSP chip U1 is provided with a data processing unit and a database. The database stores the rated temperature in advance. The data processing unit determines whether the temperature transmitted by the temperature sensor exceeds the rated temperature. When the rated temperature is exceeded, the fan F1 is controlled to start working.

[0040] The emitter of the transistor Q1 is connected to the ground terminal PGND.

[0041] The ground terminal to which the output emitter of the high-speed optical coupler U2, the emitter of the transistor Q2, and the GND terminal of the fan F1 are connected is SGND.

[0042] When the charging pile is working and charging, the temperature inside the pile will continue to rise. When it reaches the set heat dissipation temperature point, the DSP chip will output a 25k frequency FAN PWM IN to control the conduction and cutoff of the transistor Q1, thereby controlling the on and off of the light source at the input end of the high-speed optocoupler U2. The light receiver at the output end of the high-speed optocoupler U2 is also synchronously controlled to be on and off, thereby controlling the on and off of the transistor Q2, generating a FAN PWM wave, and performing PWM control on the fan speed.

[0043] When the charging pile is powered on and enters the charging state, the system will continuously detect the temperature inside the pile. When the temperature reaches the system-set cooling point, the DSP chip determines that the system needs to dissipate heat and outputs FAN PWM IN with a constant frequency of 25K. Different duty cycles represent different speeds. The duty cycle from 1%-100% corresponds to 1%-100% of the rated fan speed. According to the real-time temperature, the duty cycle is controlled to change the fan speed, thereby accurately adjusting the temperature to achieve the most appropriate and effective heat dissipation effect.

[0044] Assume that the DSP chip outputs FAN PWM IN with a duty cycle of 50%. When FAN PWM IN is at a high level, transistor Q1 is turned on, the light source at the input end of the high-speed optocoupler U2 is grounded, the internal photosensitive diode is turned on, the light receiver at the output end of the high-speed optocoupler U2 is grounded, and the node at the connection of resistors R1 and R2 is pulled low. The node is at a low level at this time, transistor Q2 is turned off, and FAN PWM is at a high level at this time.

[0045] Assume that the DSP chip outputs FAN PWM IN with a duty cycle of 50%. When FAN PWM IN is at a low level, transistor Q1 is cut off, the light source at the input end of the high-speed optocoupler U2 is disconnected and grounded, the internal photosensitive diode is cut off, the light receiver at the output end of the high-speed optocoupler U2 is disconnected and grounded, the node at the connection of resistors R1 and R2 is at a high level, transistor Q2 is turned on, and FAN PWM is pulled down to ground. At this time, FAN PWM is at a low level.

[0046] A high and low level is used as a cycle, which is repeated continuously to achieve the fan PWM speed control design; assuming that SVCC is 12V, the FAN PWM IN duty cycle is 50%, the effective voltage on the fan F1 is Vrms = SVCC*D = 12V*50% = 6V, and the corresponding speed of F1 is 50% of the rated value.

[0047] The advantages of the present invention are: without significantly changing the circuit, the fan PWM speed control function of the small DC charging pile is realized in a simple, low-cost, high-performance, and cost-effective form, the loss caused by the fan is greatly reduced, the noise to the surrounding environment is reduced, the speed control accuracy is high, stepless speed regulation can be achieved, and the isolation control scheme adopted can effectively reduce EMC, which is more friendly to the EMC design of the charging pile, and can greatly reduce the interference noise to other circuits in the pile; the invention of this design can solve the market pain points of backward fan speed control, high noise, and large interference in small DC charging piles, can be well adapted to various types of charging piles, is safe, stable and reliable, has high compatibility, and will not affect the performance parameters of the charging piles.

[0048] The present invention solves the current problems of low speed control accuracy and large interference noise of small DC charging pile fans. The key point is to use high-speed optocouplers to isolate PWM waves, greatly reduce the interference of fans on the system, and adjust the fan speed by adjusting the duty cycle. The protection point is to use this design circuit to complete the isolated fan PWM control of DC charging piles in the field of DC charging piles, and solve the market problems of unsatisfactory intelligent stepless speed regulation of small DC charging pile fans and large interference noise of non-isolated control.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive from any point of view. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention, and any reference numerals in the claims should not be considered as limiting the claims involved.

[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. An isolated fan PWM control circuit based on a small DC charging pile, characterized in that: Including DSP chip U1, high-speed optocoupler U2, transistor Q1, transistor Q2, resistor R1, resistor R2, resistor R3, resistor R4 and fan F1; The output end of the DSP chip U1 is connected to the base of the transistor Q1, and the emitter of the transistor Q1 is grounded; The collector of transistor Q1 is connected to the input cathode of high-speed optocoupler U2, and the input anode of high-speed optocoupler U2 is connected to the power supply PVCC; The output collector of the high-speed optocoupler U2 is connected to one end of the resistor R1 and one end of the resistor R2 at the same time, the other end of the resistor R1 is connected to the power supply SVCC, and the other end of the resistor R2 is connected to the base of the transistor Q2; The output emitter of the high-speed optocoupler U2 is grounded; The collector of transistor Q2 is connected to one end of resistor R3, and the other end of resistor R3 is connected to power supply SVCC. The emitter of transistor Q2 is grounded; The PWM speed control pin of the fan F1 is connected to the collector of the transistor Q2; the GND terminal of the fan F1 is grounded, and the VCC terminal of the fan F1 is connected to the power supply SVCC; The two ends of the resistor R4 are connected in parallel to the PWM speed control foot of the fan F1 and the GND end of the fan F1; The PWM speed regulating foot of the fan F1 is connected to the DSP chip U1 for communication.

2. The isolated fan PWM control circuit based on a small DC charging pile according to claim 1 is characterized in that: The emitter of the transistor Q1 is connected to the ground terminal PGND.

3. The isolated fan PWM control circuit based on a small DC charging pile according to claim 2 is characterized in that: The ground terminal to which the output emitter of the high-speed optical coupler U2, the emitter of the transistor Q2, and the GND terminal of the fan F1 are connected is SGND.

4. The isolated fan PWM control circuit based on a small DC charging pile according to claim 3 is characterized in that: The high-speed optical coupler U2 is connected to the power supply SVCC.

5. The isolated fan PWM control circuit based on a small DC charging pile according to claim 4 is characterized in that: The DSP chip U1 is connected to a temperature sensor, and the temperature sensor is installed inside the charging pile.

6. The isolated fan PWM control circuit based on a small DC charging pile according to claim 5, characterized in that: The DSP chip U1 is provided with a data processing unit and a database.

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