Control method and device for low-cost brushed electronic fan

Abstract

The invention relates to a control method of a low-cost brushed electronic fan. The control method comprises the following steps: S1, starting the brushed electronic fan; s2, setting the sampling time and the sampling period of a sampling window through a motor driving chip; s3, collecting a back electromotive force voltage and a power supply voltage in the sampling window through a motor driving chip; s4, the current rotating speed is calculated according to the collected back electromotive force voltage; s5, calculating the current input current according to the collected back electromotive force voltage and the rotating speed calculated in S4; and S6, calculating the input power according to the current calculated in the S5 and the collected power supply voltage, comparing the input power with the target power, and limiting the input power by reducing the input voltage of the electronic fan. The invention further provides a control device which is simple in structure and used for the control method. The bus current and the rotating speed are estimated through an algorithm to realize power limitation, a sampling resistor or a Hall device does not need to be added for data acquisition, and the temperature resistance level of the system is improved and the cost is reduced through MOS complementary follow current.

Description

Technical Field

[0001] The invention relates to the technical field of brushed electronic fans, and in particular to a control method and device for a low-cost brushed electronic fan. Background Art

[0002] The automotive brushless electronic fan is a key component in the vehicle thermal management system. With the development of the domestic automobile industry in recent years, the demand has also increased, thus attracting many domestic and foreign companies to participate in the brushless electronic fan manufacturing industry. The competitive pressure in the brushless electronic fan market has increased, and reducing costs can help companies provide more price-competitive products to attract customers. Traditional brushless electronic fan controllers still use external sampling circuits to obtain data, and companies need to reserve a large number of material models, so it is urgent to reduce costs by reducing material models. Therefore, the invention of a low-cost control method and device for a brushless electronic fan can help promote the development of the automotive industry.

[0003] The current mainstream control scheme for brushed electronic fans adopts the design of functions such as building sampling resistors or Hall circuits to collect current and speed information for power limitation, and uses diode freewheeling. However, there is cost pressure of high hardware cost. In view of the defects of the prior art, the present invention provides a low-cost control method and device for brushed electronic fans. Summary of the invention

[0004] In view of the above problems, the present invention provides a control method and device for a low-cost brushed electronic fan that realizes a power limiting function and reduces costs at the same time.

[0005] The technical solution adopted by the present invention to solve the above technical problems is: a control method for a low-cost brushless electronic fan, comprising the following steps:

[0006] S1, start the brushed electronic fan;

[0007] S2, setting the sampling time and sampling period of the sampling window through the motor driver chip;

[0008] S3, collecting back electromotive force voltage and power supply voltage through the motor driver chip within the sampling window;

[0009] S4, calculate the current speed according to the collected back electromotive force voltage, where the calculation formula of the current speed is: the rotor speed n and the back electromotive force U generated in the rotor o , Input electronic fan voltage U I , Back EMF constant K e The relationship is as follows

[0010]

[0011] S5, calculate the current input current according to the collected back electromotive force voltage and the speed estimated by S4, where the calculation formula of the current input current is: rotor current I and rotor speed n, input electronic fan voltage U I , Brushed electronic fan resistor R m , Back EMF constant K e The relationship is as follows

[0012]

[0013] S6, calculates the input power according to the current calculated by S5 and the collected power supply voltage, compares it with the target power, and limits the input power by reducing the electronic fan input voltage.

[0014] Preferably, the step S1 starts the brushed electronic fan in a manner of outputting through upper and lower bridge complementary MOS, and applies a dead zone to prevent the upper and lower bridge MOS from being damaged due to direct conduction.

[0015] Preferably, the step S3 of collecting the back electromotive force voltage by the motor driving chip comprises:

[0016] S301, a sampling window for the back electromotive force voltage generated by the brushless electronic fan freewheeling is reserved in the control motor drive chip, and the back electromotive force voltage is obtained through the digital-to-analog conversion module of the motor drive chip after the voltage is stabilized;

[0017] S302, performing software digital filtering on the back electromotive force voltage obtained in step S301.

[0018] The present invention also provides a control device for a low-cost brushed electronic fan, comprising a motor drive chip, an upper bridge drive MOS, a lower bridge drive MOS, a positive bus and a negative bus, wherein the positive bus is connected to the upper bridge drive MOS drain, the upper bridge MOS control port of the motor drive chip is connected to the upper bridge drive MOS gate, the back electromotive force sampling port of the motor drive chip is simultaneously connected to the upper bridge drive MOS source, the positive electrode of the brushed electronic fan and the lower bridge drive MOS drain, and the upper bridge drive MOS source and the lower bridge drive MOS drain are connected in parallel to the positive electrode of the brushed electronic fan, the lower bridge MOS control port of the motor drive chip is connected to the lower bridge drive MOS gate, and the lower bridge drive MOS source and the negative electrode of the brushed electronic fan are connected in parallel to the negative bus.

[0019] Preferably, the model of the motor driver chip is TLE9854QXW.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention calculates the fan speed and bus current by back electromotive force, which not only realizes the power limiting function, but also eliminates the sampling resistor and the Hall sensor compared with the traditional data acquisition method, so the cost is lower than the traditional solution;

[0022] 2. The present invention adopts MOS complementary output, which has the advantage of improving the temperature resistance level of the device. Due to the use of MOS complementary output, the freewheeling diode is eliminated, reducing cost pressure; secondly, the use of MOS complementary output has higher control accuracy. The speed of the brushed electronic fan obtained by the control method has an error range of 3% to 5% from the actual speed of the brushed electronic fan. At the same time, the input current of the brushed electronic fan obtained by the control method has an error range of 3% to 5% from the actual input current of the brushed electronic fan. Therefore, the power control obtained by the control method has an error range of 3% to 5% from the target power of the actual brushed electronic fan. ;

[0023] 3. The control method and device of the present invention are simple in design, highly reliable and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of a sampling circuit for the upper and lower bridge complementary control output stage of the control device of the present invention;

[0025] Figure 2 It is a flowchart of the control method of the present invention. DETAILED DESCRIPTION

[0026] The following will be combined Figure 1-2 The present invention is described in detail. The exemplary embodiments and descriptions of the present invention are used to explain the present invention but are not intended to limit the present invention.

[0027] A control method for a low-cost brushless electronic fan comprises the following steps:

[0028] S1, start the brushed electronic fan. Specifically, the brushed electronic fan is started by outputting through the upper and lower bridge complementary MOS, and applying a dead zone to prevent the upper and lower bridge MOS from being damaged by direct conduction;

[0029] S2, setting the sampling time and sampling period of the sampling window through the motor driver chip;

[0030] S3, collecting back electromotive force voltage and power supply voltage through the motor driver chip within the sampling window;

[0031] S4, calculate the current speed according to the collected back electromotive force voltage, where the calculation formula of the current speed is: the rotor speed n and the back electromotive force U generated in the rotor o , Input electronic fan voltage U I , Back EMF constant Ke The relationship is as follows

[0032]

[0033] S5, calculate the current input current according to the collected back electromotive force voltage and the speed estimated by S4, where the calculation formula of the current input current is: rotor current I and rotor speed n, input electronic fan voltage U I , Brushed electronic fan resistor R m , Back EMF constant K e The relationship is as follows

[0034]

[0035] S6, calculates the input power according to the current calculated by S5 and the collected power supply voltage, compares it with the target power, and limits the input power by reducing the electronic fan input voltage.

[0036] Specifically, the step S3 of the motor driving chip collecting the back electromotive force voltage includes:

[0037] S301, a sampling window for the back electromotive force voltage generated by the brushless electronic fan freewheeling is reserved in the control motor drive chip, and the back electromotive force voltage is obtained through the digital-to-analog conversion module of the motor drive chip after the voltage is stabilized;

[0038] S302, performing software digital filtering on the back electromotive force voltage obtained in step S301, in order to obtain a relatively stable back electromotive force voltage and eliminate the influence of clutter signals.

[0039] The present invention also provides a low-cost control device for a brushed electronic fan, comprising a motor drive chip 9, an upper bridge drive MOS 2, a lower bridge drive MOS 3, a positive bus 1 and a negative bus 5, the model of the motor drive chip is TLE9854QXW, the positive bus is connected to the upper bridge drive MOS drain, the upper bridge MOS control port 6 of the motor drive chip is connected to the upper bridge drive MOS gate, the back electromotive force sampling port 7 of the motor drive chip is simultaneously connected to the upper bridge drive MOS source, the positive electrode of the brushed electronic fan 4 and the lower bridge drive MOS drain, and the upper bridge drive MOS source and the lower bridge drive MOS drain are connected in parallel to the positive electrode of the brushed electronic fan, the lower bridge MOS control port 8 of the motor drive chip is connected to the lower bridge drive MOS gate, and the lower bridge drive MOS source and the negative electrode of the brushed electronic fan are connected in parallel to the negative bus.

[0040] During the implementation process, the motor driver chip generates a signal to control the complementary outputs of the upper bridge driver MOS and the lower bridge driver MOS to start the brushed electronic fan. During the operation, the complementary outputs of the upper bridge driver MOS and the lower bridge driver MOS are periodically and briefly stopped, so that the back-electromotive force sampling port of the motor driver chip collects the back-electromotive force voltage of the brushed electronic fan and performs calculations. According to the calculation results, the amplitude of the complementary outputs of the upper bridge driver MOS and the lower bridge driver MOS can be limited.

[0041] The method of calculating the fan speed and bus current by back electromotive force not only realizes the power limiting function, but also, compared with the traditional method of data acquisition through sampling resistors and Hall sensors, the cost is lower than the traditional solution. The current solution cancels the sampling resistor and Hall sensor. Specifically, the use of MOS complementary output has the advantage of improving the temperature resistance level of the device. Due to the use of MOS complementary output, the freewheeling diode is cancelled, the cost pressure is reduced, and the use of MOS complementary output has higher control accuracy. Specifically, the speed of the brushed electronic fan obtained by the control method has an error range of 3% to 5% with the actual speed of the brushed electronic fan; the input current of the brushed electronic fan obtained by the control method has an error range of 3% to 5% with the actual input current of the brushed electronic fan; the power control obtained by the control method has an error range of 3% to 5% with the actual target power of the brushed electronic fan. The control method and device are simple in design, high in reliability and accuracy.

[0042] The technical solutions provided by the embodiments of the present invention are introduced in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the embodiments of the present invention. The description of the above embodiments is only applicable to help understand the principles of the embodiments of the present invention. At the same time, for those skilled in the art, according to the embodiments of the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A control method for a low-cost brushless electronic fan, characterized in that: The following steps are involved: S1, start the brushed electronic fan; S2, setting the sampling time and sampling period of the sampling window through the motor driver chip; S3, collecting back electromotive force voltage and power supply voltage through the motor driver chip within the sampling window; S4, calculate the current speed according to the collected back electromotive force voltage, where the calculation formula of the current speed is: the rotor speed n and the back electromotive force U generated in the rotor o , Input electronic fan voltage U I , Back EMF constant K e The relationship is as follows S5, calculate the current input current according to the collected back electromotive force voltage and the speed estimated by S4, where the calculation formula of the current input current is: rotor current I and rotor speed n, input electronic fan voltage U I , Brushed electronic fan resistor R m , Back EMF constant K e The relationship is as follows S6, calculates the input power according to the current calculated by S5 and the collected power supply voltage, compares it with the target power, and limits the input power by reducing the electronic fan input voltage.

2. The control method of the low-cost brushless electronic fan according to claim 1, characterized in that: The step S1 starts the brushed electronic fan in a manner of outputting through the upper and lower bridge complementary MOS, and applies a dead zone to prevent the upper and lower bridge MOS from being damaged by direct conduction.

3. The control method of the low-cost brushed electronic fan according to claim 1, characterized in that: The step S3 of the motor driving chip collecting the back electromotive force voltage comprises: S301, a sampling window for the back electromotive force voltage generated by the brushless electronic fan freewheeling is reserved in the control motor drive chip, and the back electromotive force voltage is obtained through the digital-to-analog conversion module of the motor drive chip after the voltage is stabilized; S302, performing software digital filtering on the back electromotive force voltage obtained in step S301.

4. A low-cost brushless electronic fan control device, characterized in that: The invention comprises a motor drive chip (9), an upper bridge drive MOS (2), a lower bridge drive MOS (3), a positive bus (1) and a negative bus (5), wherein the positive bus is connected to the upper bridge drive MOS drain, the upper bridge MOS control port (6) of the motor drive chip is connected to the upper bridge drive MOS gate, the back electromotive force sampling port (7) of the motor drive chip is simultaneously connected to the upper bridge drive MOS source, the positive pole of a brushed electronic fan (4) and the lower bridge drive MOS drain, and the upper bridge drive MOS source and the lower bridge drive MOS drain are connected in parallel to the positive pole of the brushed electronic fan, the lower bridge MOS control port (8) of the motor drive chip is connected to the lower bridge drive MOS gate, and the lower bridge drive MOS source and the negative pole of the brushed electronic fan are connected in parallel to the negative bus.

5. The low-cost brushed electronic fan control device according to claim 4, characterized in that: The model of the motor driver chip is TLE9854QXW.

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