Control method of brush direct current motor for air inlet heating fan

Abstract

The invention provides a control method of a brush direct current motor for an air inlet heating fan, which comprises the following steps of: adopting an isolation driving mode, adopting a photoelectric isolation device to drive a power MOS (Metal Oxide Semiconductor) tube for driving output, and adopting a Hall type isolation current in an output loop to collect the driving current of the fan so as to realize digital logic and power driving space isolation; by adopting an adjusting mode of combining control software and a hardware circuit, the starting, speed regulation and emergency control under fault conditions of the brush direct current motor are realized; in the starting process, transient large current suppression and flexible starting are achieved through hardware current closed-loop control; in the working process, fault diagnosis of fan stalling is achieved through current and current over-limit double feedback. The control method of the brush direct current motor for the air inlet heating fan has the beneficial effects that on-line diagnosis of damage faults of the fan brush is realized through current value acquisition in the working process, and early warning of component faults is realized.

Description

Technical Field

[0001] The invention belongs to the field of diesel engine application, and in particular relates to a brushed DC motor control method for an intake heating fan. Background Art

[0002] In the application field of diesel engines, the air entering the diesel engine needs to be heated when working at low temperatures. The fan is an important control of the intake heating system. Generally, a fan with a brushed DC motor is selected. The commonly used control is the control of the relay. The principle of this method is simple. It only needs to control the attraction and release of the relay to complete the control of the fan components, but there is no feedback on the status of the fan components, and the online fault diagnosis of the components cannot be realized. In order to achieve the regulation and control of the fan speed, PWM modulation control is required. Under this method, the commonly used relays cannot meet the high-frequency regulation and control, and solid-state relays need to be used. However, the cost of solid-state relays is relatively high. In general, power regulation MOS tubes are used instead. However, the starting process of the brushed DC motor is relatively special. The instantaneous current is very large during starting, but the current is very small after the speed increases. If the instantaneous large current during starting is considered, the selected power drive device needs to consider the large current amplitude, and the size and cost of the power device will increase accordingly. In addition, when the motor starts, the circuit board and power components in the entire drive circuit have a greater impact, and the external electromagnetic radiation is large, which will cause interference to other circuits. Summary of the invention

[0003] In view of this, the present invention aims to provide a brushed DC motor control method for an air intake heating fan to solve the problems of high cost and interference with other circuits when the motor is driven.

[0004] To achieve the above object, the technical solution of the present invention is achieved as follows:

[0005] A control method for a brushed DC motor for an intake heating fan includes a control circuit, which includes a CPU, an OUT1 port of the CPU is connected to VCC via R12 and a fault indicator LED, an IN port of the CPU is connected to VCC via R1, an A / D port of the CPU is connected to GND via C3, connected to the output end of a Hall current acquisition module H1 via R7, and then connected to GND, the output end of the Hall current acquisition module H1 is connected to GND via C5 via R10, and connected to the negative input end of a current feedback comparator U2B, the positive input end of the current feedback comparator U2B is connected to GND via R11, connected to 5VR via R9, and connected to the output end of the current feedback comparator U2B via R12, the output end of the current feedback comparator U2B is connected to the IN port of the CPU; the PWM port of the CPU is connected to the negative input end of the control comparator U1B via R6. The positive input end of the control comparator U1B is connected to GND through R5 and to 5VR through R8. The output end of the control comparator U1B is connected to the IN port of the CPU and the B set of the triode Q1. The E set of the triode Q1 is connected to GND. The C set of the triode Q1 is connected to the second pin of the photoelectric isolator U3 through R2. The first pin of the photoelectric isolator U3 is connected to VCC. The third pin of the photoelectric isolator U3 is connected to GP. The fourth pin of the photoelectric isolator U3 is connected to the first end of R3. The second end of R3 is connected to the G pole of the PMOS tube Q2 and to the power supply BAT through the voltage regulator tube Z1. The voltage regulator tube Z1 is also connected in parallel with an R4. The power supply BAT is connected to the S pole of the PMOS tube Q2. The D pole of the PMOS tube Q2 is connected to GP through the input end of the Hall current acquisition module H1 and the motor M1 and to GP through the absorption diode D1.

[0006] The control method of the control circuit is:

[0007] During the start-up control process, starting from t0, the CPU outputs a low-level PWM signal, and controls the comparator U1B to shut off the chip's internal OC gate output; at this time, the current passing through the motor is 0, the Hall current acquisition module H1 output voltage signal V1 is also 0, and the feedback comparator U2B also shuts off the chip's internal OC gate output; the "AND" signal V2 formed by the outputs of U1B and U2B becomes a high level through the pull-up resistor R1, driving the triode Q1 to turn on, the input end of the optoelectronic isolation device U3 to turn on, and the output end of U3 to the power ground GP. The power supply BAT is divided by resistors R4 and R3, and the PMOS tube Q2 is turned on. The power supply is applied to the motor M1, and the current of the motor M1 begins to increase. When the power supply BAT increases, the protection voltage regulator Z1 is applied to the control voltage of the PMOS tube Q2.

[0008] During t0-t01, the current of motor M1 begins to increase, and the output voltage signal V1 of the Hall current acquisition module H also increases proportionally. The "AND" signal V2 formed by the outputs of U1B and U2B continues to be high level. This signal is also input to the IN pin of the CPU, and the CPU counts the adjustments during the starting process of the motor.

[0009] At t01, the current through the motor M reaches the upper limit voltage u1 set by the voltage divider circuit R9 and R11, the output of the feedback comparator U2B is reversed, the OC gate inside the chip is turned on, the V2 signal becomes low level, the driving transistor Q1 is turned off, the input end of the optoelectronic isolation device U3 is turned off, the voltages across the voltage divider resistor R4 are equal, the PMOS tube Q2 is turned off, and the power supply is no longer applied to the motor M1. Since the motor is equivalent to an inductive load, the current in the motor M1 forms a loop through the freewheeling diode D1 and the Hall circuit acquisition module H1, and the current begins to decrease;

[0010] During t01-t02, the current gradually decreases;

[0011] At t02, the current through the motor M reaches the lower limit voltage u2 set by the voltage divider circuit R9 and R11, the output of the feedback comparator U2B is reversed, the OC gate inside the chip is turned off, the V2 signal becomes high level, driving the transistor Q1 to turn on, the input end of the optoelectronic isolation device U3 to turn on, the PMOS tube Q2 to turn on, the power supply is applied to the motor M1 again, and the current in the motor M1 starts to rise again;

[0012] During t02~t03, t03~t04, t04~t05, t05~t06, repeat the above adjustment process;

[0013] After the current rises from t06 to t07, it continues to decrease from t07 until t1. During this period, the CPU cannot detect the high or low level changes of the input signal IN. At the same time, combined with the voltage signal u3 collected by the A / D terminal, it confirms that the motor starts successfully.

[0014] Furthermore, the brushed DC motor control method for the air intake heating fan adopts PWM open-loop control with a period of T in the later stage, and t1-t2 and t2-t3 are respectively one control period.

[0015] Furthermore, t0~t1 and t1~t2 are normal control cycles. During t2~t3, the current starts to rise at t21. At t22, the CPU receives an input signal IN which reverses from high level to low level, and receives a high level to low level reversal at t23 and t24. At the same time, combined with the voltage signal collected at the A / D terminal, it is confirmed that the motor is stalled during operation, and the CPU is controlled to cut off the control output of the motor in real time.

[0016] Furthermore, t0-t1 and t1-t2 are normal control cycles. During t2-t3, the voltage signal collected by the CPU through the A / D terminal drops at t21 and also drops at t22, confirming that the motor has brush wear during operation and controlling the CPU to output a motor brush fault indication.

[0017] Furthermore, the R1 is a pull-up resistor.

[0018] Furthermore, R2, R3, and R12 are current limiting resistors.

[0019] Furthermore, R4, R5, R8, R9, and R11 are voltage-dividing resistors.

[0020] Furthermore, R7 and R10 are filter resistors.

[0021] Compared with the prior art, the brushless DC motor control method for the air intake heating fan of the present invention has the following advantages:

[0022] (1) The control method of the brushed DC motor for the air intake heating fan described in the present invention adopts an isolated drive mode, and the drive output adopts a photoelectric isolation device to drive the power MOS tube. The output circuit adopts a Hall-type isolation current to collect the drive current of the fan, so as to realize the spatial isolation of digital logic and power drive; a regulation mode combining control software and hardware circuit is adopted to realize the starting, speed regulation and emergency control of the brushed DC motor in the event of a fault; during the starting process, the hardware current closed-loop control is used to realize transient large current suppression and flexible starting; during the working process, the current and current over-limit dual feedback is used to realize the fault diagnosis of the fan stalling; at the same time, by collecting the current value during the working process, the online diagnosis of the fan brush damage fault is realized, and the early warning of the component failure is realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 A control circuit diagram of a brushed DC motor according to an embodiment of the present invention;

[0025] Figure 2 A motor starting control logic diagram according to an embodiment of the present invention;

[0026] Figure 3 A motor stall diagnosis logic diagram according to an embodiment of the present invention;

[0027] Figure 4This is a motor brush damage diagnosis logic diagram according to an embodiment of the present invention. DETAILED DESCRIPTION

[0028] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0029] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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", "second", and the like are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", and the like may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0030] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "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; 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 by specific circumstances.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and in conjunction with embodiments.

[0032] A method for controlling a brushless DC motor for an air intake heating fan, such as Figures 1 to 4As shown, the control circuit includes a CPU, the OUT1 port of the CPU is connected to VCC via R12 and a fault indicator LED, the IN port of the CPU is connected to VCC via R1, the A / D port of the CPU is connected to GND via C3, connected to the output end of the Hall current acquisition module H1 via R7, and then connected to GND, the output end of the Hall current acquisition module H1 is connected to GND via C5 via R10, and connected to the negative input end of the current feedback comparator U2B, the positive input end of the current feedback comparator U2B is connected to GND via R11, connected to 5VR via R9, and connected to the output end of the current feedback comparator U2B via R12, and the output end of the current feedback comparator U2B is connected to the IN port of the CPU; the PWM port of the CPU is connected to the negative input end of the control comparator U1B via R6, and the control comparator U The positive input end of 1B is connected to GND through R5 and to 5VR through R8, the output end of the control comparator U1B is connected to the IN port of the CPU and the B set of the triode Q1, the E set of the triode Q1 is connected to GND, the C set of the triode Q1 is connected to the second pin of the photoelectric isolator U3 through R2, the first pin of the photoelectric isolator U3 is connected to VCC, the third pin of the photoelectric isolator U3 is connected to GP, the fourth pin of the photoelectric isolator U3 is connected to the first end of R3, the second end of R3 is connected to the G pole of the PMOS tube Q2 and to the power supply BAT through the voltage regulator tube Z1, the voltage regulator tube Z1 is also connected in parallel with a R4, the power supply BAT is connected to the S pole of the PMOS tube Q2, the D pole of the PMOS tube Q2 is connected to GP through the input end of the Hall current acquisition module H1 and the motor M1, and is connected to GP through the absorption diode D1;

[0033] The control method of the control circuit is:

[0034] During the start-up control process, at t0, the CPU outputs a PWM signal of low level, and the control comparator U1B turns off the OC gate output inside the chip; at this time, the current passing through the motor is 0, the output voltage signal V1 of the Hall current acquisition module H1 is also 0, and the feedback comparator U2B also turns off the OC gate output inside the chip; the "AND" signal V2 formed by the outputs of U1B and U2B becomes high level through the pull-up resistor R1, driving the triode Q1 to turn on, the input end of the optoelectronic isolation device U3 to turn on, the output end of U3 to the power ground GP, the power supply BAT is divided by resistors R4 and R3, the PMOS tube Q2 is turned on, the power supply is applied to the motor M1, and the current of the motor M1 begins to increase. When the power supply BAT increases, the protection voltage regulator Z1 does not exceed the control voltage applied to the PMOS tube Q2.

[0035] During t0-t01, the current of motor M1 begins to increase, and the output voltage signal V1 of the Hall current acquisition module H also increases proportionally. The "AND" signal V2 formed by the outputs of U1B and U2B continues to be high level. This signal is also input to the IN pin of the CPU, and the CPU counts the adjustments during the starting process of the motor.

[0036] At t01, the current through the motor M reaches the upper limit voltage u1 set by the voltage divider circuit R9 and R11, the output of the feedback comparator U2B is reversed, the OC gate inside the chip is turned on, the V2 signal becomes low level, driving the transistor Q1 to turn off, the input end of the optoelectronic isolation device U3 is turned off, the voltages across the voltage divider resistor R4 are equal, the PMOS tube Q2 is turned off, and the power supply is no longer applied to the motor M1. Since the motor is equivalent to an inductive load, the current in the motor M1 forms a loop through the freewheeling diode D1 and the Hall circuit acquisition module H1, and the current begins to decrease.

[0037] During t01 to t02, the current decreases gradually.

[0038] At t02, the current through the motor M reaches the lower limit voltage u2 set by the voltage divider circuit R9 and R11, the output of the feedback comparator U2B is reversed, the OC gate inside the chip is turned off, the V2 signal becomes a high level, driving the transistor Q1 to turn on, the input end of the optoelectronic isolation device U3 to turn on, the PMOS tube Q2 to turn on, the power supply is applied to the motor M1 again, and the current in the motor M1 starts to rise again.

[0039] The above adjustment process is repeated during t02~t03, t03~t04, t04~t05, and t05~t06.

[0040] After the current rises from t06 to t07, it continues to decrease from t07 until t1. During this period, the CPU cannot detect the high or low level changes of the input signal IN. At the same time, combined with the voltage signal u3 collected by the A / D terminal, it confirms that the motor starts successfully.

[0041] R1 is a pull-up resistor; R2, R3, and R12 are current limiting resistors.

[0042] R4, R5, R8, R9, and R11 are voltage divider resistors; R7 and R10 are filter resistors.

[0043] The CPU can be a model that can control the operation of the motor.

[0044] The transistor Q1 is an NPN transistor.

[0045] Preferably, a PWM open-loop control with a period of T is adopted in the later stage, and t1-t2 and t2-t3 are respectively one control period, and the motor operation is continuously controlled in this control mode.

[0046] like Figure 3 As shown, t0~t1 and t1~t2 are normal control cycles. During t2~t3, the current starts to rise at t21. At t22, the CPU receives an input signal IN which reverses from high level to low level, and receives a high level to low level reversal at t23 and t24. At the same time, combined with the voltage signal collected at the A / D terminal, it is confirmed that the motor is stalled during operation, and the CPU is controlled to cut off the control output of the motor in real time to prevent the motor from being stalled and overheated and damaged.

[0047] like Figure 4 As shown, t0~t1 and t1~t2 are normal control cycles. During t2~t3, the voltage signal collected by the CPU through the A / D terminal drops at t21 and also drops at t22, confirming that the motor brushes are worn during operation. The CPU is controlled to output a motor brush fault indication to remind the user to replace the motor.

[0048] The control method of this scheme adopts an isolated drive mode. The drive output adopts an optoelectronic isolation device to drive the power MOS tube. The output circuit adopts a Hall-type isolation current to collect the drive current of the fan, so as to realize the spatial isolation of digital logic and power drive. The adjustment method combining control software and hardware circuit is adopted to realize the starting, speed regulation and emergency control of the brushed DC motor in the event of a fault. During the starting process, the hardware current closed-loop control is used to realize transient large current suppression and flexible starting. During the working process, the dual feedback of current and current overlimit is used to realize the fault diagnosis of fan stall. At the same time, the current value is collected during the working process to realize the online diagnosis of the fan brush damage fault and realize the early warning of component failure.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for controlling a brushless DC motor for an air intake heating fan, characterized in that: The control circuit includes a CPU, wherein the OUT1 port of the CPU is connected to VCC via R12 and a fault indicator LED, the IN port of the CPU is connected to VCC via R1, the A / D port of the CPU is connected to GND via C3, connected to the output end of the Hall current acquisition module H1 via R7, and then connected to GND, the output end of the Hall current acquisition module H1 is connected to GND via C5 via R10, and connected to the negative input end of the current feedback comparator U2B, the positive input end of the current feedback comparator U2B is connected to GND via R11, connected to 5VR via R9, and connected to the output end of the current feedback comparator U2B via R12, and the output end of the current feedback comparator U2B is connected to the IN port of the CPU; the PWM port of the CPU is connected to the negative input end of the control comparator U1B via R6, and the control comparator U1 The positive input end of B is connected to GND through R5 and to 5VR through R8, the output end of the control comparator U1B is connected to the IN port of the CPU and the B set of the triode Q1, the E set of the triode Q1 is connected to GND, the C set of the triode Q1 is connected to the second pin of the photoelectric isolator U3 through R2, the first pin of the photoelectric isolator U3 is connected to VCC, the third pin of the photoelectric isolator U3 is connected to GP, the fourth pin of the photoelectric isolator U3 is connected to the first end of R3, the second end of R3 is connected to the G pole of the PMOS tube Q2 and to the power supply BAT through the voltage regulator tube Z1, the voltage regulator tube Z1 is also connected in parallel with an R4, the power supply BAT is connected to the S pole of the PMOS tube Q2, the D pole of the PMOS tube Q2 is connected to GP through the input end of the Hall current acquisition module H1 and the motor M1, and is connected to GP through the absorption diode D1; The control method of the control circuit is: During the start-up control process, starting from t0, the CPU outputs a PWM signal of low level, and controls the comparator U1B to shut off the OC gate output inside the chip; at this time, the current passing through the motor is 0, the output voltage signal V1 of the Hall current acquisition module H1 is also 0, and the feedback comparator U2B also shuts off the OC gate output inside the chip; the "AND" signal V2 formed by the outputs of U1B and U2B becomes high level through the pull-up resistor R1, driving the triode Q1 to turn on, the input end of the optoelectronic isolation device U3 to turn on, and the output end of U3 to the power ground GP. The power supply BAT is divided by resistors R4 and R3, the PMOS tube Q2 is turned on, and the power supply is applied to the motor M1. The current of the motor M1 begins to increase, and the protection voltage regulator Z1 does not exceed the control voltage applied to the PMOS tube Q2 when the power supply BAT increases; During t0~t01, the current of motor M1 begins to increase, and the output voltage signal V1 of the Hall current acquisition module H also increases proportionally. The "AND" signal V2 formed by the outputs of U1B and U2B continues to be high level. This signal is also input to the IN pin of the CPU. The CPU counts the adjustments during the starting process of the motor. At t01, the current through the motor M reaches the upper limit voltage u1 set by the voltage divider circuit R9 and R11, the output of the feedback comparator U2B is reversed, the OC gate inside the chip is turned on, the V2 signal becomes low level, the driving transistor Q1 is turned off, the input end of the optoelectronic isolation device U3 is turned off, the voltages across the voltage divider resistor R4 are equal, the PMOS tube Q2 is turned off, and the power supply is no longer applied to the motor M1. Since the motor is equivalent to an inductive load, the current in the motor M1 forms a loop through the freewheeling diode D1 and the Hall circuit acquisition module H1, and the current begins to decrease; During t01-t02, the current gradually decreases; At t02, the current through the motor M reaches the lower limit voltage u2 set by the voltage divider circuit R9 and R11, the output of the feedback comparator U2B is reversed, the OC gate inside the chip is turned off, the V2 signal becomes high level, driving the transistor Q1 to turn on, the input end of the optoelectronic isolation device U3 to turn on, the PMOS tube Q2 to turn on, the power supply is applied to the motor M1 again, and the current in the motor M1 starts to rise again; During t02~t03, t03~t04, t04~t05, t05~t06, repeat the above adjustment process; After the current rises from t06 to t07, it continues to decrease from t07 until t1. During this period, the CPU cannot detect the high or low level changes of the input signal IN. At the same time, combined with the voltage signal u3 collected by the A / D terminal, it confirms that the motor starts successfully.

2. A brushless DC motor control method for an air intake heating fan according to claim 1, characterized in that: In the later stage, PWM open-loop control with a period of T is adopted, and t1~t2 and t2~t3 are one control period respectively.

3. A brushless DC motor control method for an air intake heating fan according to claim 2, characterized in that: t0~t1, t1~t2 are normal control cycles. During t2~t3, the current starts to rise at t21. At t22, the CPU receives an input signal IN that reverses from high level to low level, and receives a high level to low level reversal at t23 and t24. Combined with the voltage signal collected at the A / D terminal, it is confirmed that the motor is stalled during operation, and the CPU is controlled to cut off the motor control output in real time.

4. A brushless DC motor control method for an air intake heating fan according to claim 2, characterized in that: t0~t1 and t1~t2 are normal control cycles. During t2~t3, the voltage signal collected by the CPU through the A / D terminal drops at t21 and also drops at t22, confirming that the motor brushes are worn during operation and controlling the CPU to output a motor brush fault indication.

5. A brushless DC motor control method for an air intake heating fan according to claim 1, characterized in that: R1 is a pull-up resistor.

6. A brushless DC motor control method for an air intake heating fan according to claim 1, characterized in that: R2, R3, and R12 are current limiting resistors.

7. A brushless DC motor control method for an air intake heating fan according to claim 1, characterized in that: R4, R5, R8, R9, and R11 are voltage-dividing resistors.

8. A brushless DC motor control method for an air intake heating fan according to claim 1, characterized in that: R7 and R10 are filter resistors.

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