BLDC electronic speed controller intelligent starting protection control method

Abstract

The invention discloses a BLDC electrically tunable intelligent starting protection control method. The method comprises the steps that a phase current threshold Ia is preset according to the continuous current-carrying capacity of a power MOSFET body diode of an electrically tunable circuit MOS device, and an overcurrent threshold Ib is preset according to the overcurrent capacity of the electrically tunable circuit MOS device; determining a phase current protection threshold value Ip according to the phase current threshold value Ia and the overcurrent threshold value Ib; entering an interruption mode when the PWM chopping period is ended; collecting the current phase current Ic; comparing the current phase current Ic with a phase current protection threshold value Ip; determining the maximum duty ratio PWMmax of the PWM signal according to the comparison result of the current phase current Ic and the phase current protection threshold value Ip; and comparing the duty ratio DutyIn of the PWMin controlled and input by the user with the maximum duty ratio DutyMax of the PWM signal, and determining the duty ratio of the actual output PWMout of the electronic speed controller. According to the invention, the starting current of the electronic speed controller is accurately controlled, and overcurrent or over-temperature is avoided.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric speed regulator starting protection, and in particular relates to a BLDC electric speed regulator intelligent starting protection control method. Background Art

[0002] In the field of electric speed controllers (ESCs) for brushless DC (BLDC) motors, protection measures during the startup phase are key to ensuring safe operation of the equipment. Currently, the method commonly used in the industry is to limit the maximum throttle output during the startup phase to prevent the ESC from being damaged due to excessive current. However, this protection strategy has obvious limitations in practical applications.

[0003] First, the difference in motor characteristics has a significant impact on the protection effect. Different types of BLDC motors have differences in resistance and inductance parameters, resulting in significant differences in the starting current of different motors under the same throttle output conditions. Specifically, for motors with larger inductance (mH level), the cutoff frequency of the current loop is reduced, the current acceleration is reduced, and the response time is extended; while for motors with smaller inductance (uH level), the current change rate is larger, increasing the risk of overcurrent.

[0004] Secondly, the existing protection mechanism is too simple. The current technology mainly relies on limiting the maximum throttle to control the output current of the ESC, but fails to dynamically adjust according to changes in the motor load. This limits the ESC's adaptability to high loads or special working conditions and cannot effectively ensure its safe operation.

[0005] Finally, the hysteresis of the ESC protection is also a problem. Existing overcurrent protection usually takes limiting measures only after the overcurrent occurs. During the startup phase, due to the rapid changes in motor characteristics and loads, this protection mechanism has the risk of false triggering, which not only limits the application scope of the ESC, but also may bring the risk of overheating or damage, making it difficult for existing technologies to adapt to changes in the motor's operating status in real time.

[0006] In summary, the prior art has obvious deficiencies in the startup protection of the BLDC motor ESC, and a more accurate and dynamic protection method is needed to improve the safety and reliability of the ESC. Summary of the invention

[0007] The object of the present invention is to provide a BLDC electric speed controller intelligent startup protection control method to achieve accurate control of the startup current of the electric speed controller to avoid overcurrent or overtemperature.

[0008] In order to achieve the above object, the present invention adopts the following technical solutions:

[0009] The BLDC electric speed controller intelligent startup protection control method comprises the following steps:

[0010] The phase current threshold Ia is preset according to the continuous current carrying capacity of the power MOSFET body diode of the MOS device of the electric regulation circuit, and the overcurrent threshold Ib is preset according to the overcurrent capacity of the MOS device of the electric regulation circuit;

[0011] Determine a phase current protection threshold Ip according to the phase current threshold Ia and the overcurrent threshold Ib;

[0012] Entering interrupt mode at the end of the PWM chopping cycle:

[0013] Collect the current phase current Ic;

[0014] Compare the current phase current Ic with the phase current protection threshold Ip;

[0015] Determine the maximum duty cycle PWMmax of the PWM signal according to the comparison result between the current phase current Ic and the phase current protection threshold Ip;

[0016] The duty cycle DutyIn of the user-controlled input PWMin is compared with the maximum duty cycle DutyMax of the PWM signal to determine the duty cycle of the actual output PWMout of the ESC.

[0017] In one embodiment, the step of determining the maximum duty cycle PWMmax of the PWM signal according to the comparison result of the current phase current Ic and the phase current protection threshold Ip is specifically:

[0018] Compare the current phase current Ic with the phase current protection threshold Ip;

[0019] If the current phase current value Ic exceeds the phase current protection threshold Ip, the maximum duty cycle PWMmax of the PWM signal is reduced;

[0020] If the current phase current value Ic is less than K times the phase current protection threshold Ip, the maximum duty cycle DutyMax of the PWM signal continues to increase;

[0021] If it is greater than or equal to K times of the phase current protection threshold Ip and less than or equal to the phase current protection threshold Ip, the maximum duty cycle DutyMax of the current PWM signal remains unchanged;

[0022] Wherein, K is a constant greater than 0 and less than 1.

[0023] In one embodiment, the step of comparing the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal to determine the duty cycle DutyOut of the actual output PWMout of the ESC is specifically as follows:

[0024] Compare the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal;

[0025] If the duty cycle DutyIn of the user-controlled input PWMin is less than the maximum duty cycle DutyMax of the PWM signal, the duty cycle of the actual output PWMout of the ESC is DutyIn;

[0026] If the duty cycle DutyIn of the user-controlled input PWMin is greater than the maximum duty cycle DutyMax of the PWM signal, the duty cycle of the actual output PWMout of the ESC is DutyMax.

[0027] In one of the embodiments, the step of determining the phase current protection threshold Ip based on the phase current threshold Ia and the overcurrent threshold Ib includes: during the motor startup phase, judging the driving mode of the electric regulator; if the electric regulator adopts a synchronous rectification driving mode, the overcurrent threshold Ib is used as the phase current protection threshold Ip; if the electric regulator adopts a non-synchronous rectification driving mode, the phase current threshold Ia is used as the phase current protection threshold Ip.

[0028] In one of the embodiments, the BLDC electric speed controller intelligent startup protection control method further includes a step of performing over-current protection within a PWM chopping cycle.

[0029] In one embodiment, the step of performing overcurrent protection during the PWM chopping cycle includes the following steps:

[0030] Step S21, setting the ADC voltage threshold Vmax to the actual ADC value Vp corresponding to the current phase current protection threshold Ip through the ADC, that is, Vmax=Vp;

[0031] Step S22, collecting the phase current Ic of the motor in real time through the ADC, calculating the current ADC voltage Vc corresponding to the phase current Ic, and determining whether the current ADC voltage Vc is greater than the voltage threshold Vmax;

[0032] Step S23: If the current ADC voltage Vc is greater than the voltage threshold Vmax, the PWM chopping output of the current cycle of the actual output PWMout of the electric regulator is turned off, otherwise, continue to execute step S22.

[0033] In one embodiment, the constant K is 2 / 3.

[0034] In one of the embodiments, the phase current threshold Ia is 0.8 times the maximum freewheeling capability of the body diode of the MOS device of the electrical modulation circuit.

[0035] In one of the embodiments, the overcurrent threshold Ib is 0.8 times the overcurrent capacity of the MOS device of the electrical modulation circuit when it is turned on.

[0036] In one embodiment, the BLDC electric speed controller intelligent startup protection control method further includes a bus overcurrent protection step, and the bus overcurrent protection step includes:

[0037] Preset the maximum bus current Imax;

[0038] Real-time detection of current bus current Im;

[0039] Determine whether the current bus current Im is greater than the preset maximum bus current Imax;

[0040] If the current bus current Im is greater than the preset maximum bus current Imax, the PWM signal output is turned off.

[0041] Another object of the present invention is to provide a BLDC electric speed controller intelligent startup protection control method, comprising the following steps:

[0042] The phase current threshold Ia is preset according to the continuous current carrying capacity of the power MOSFET body diode of the MOS device of the electric regulation circuit, and the overcurrent threshold Ib is preset according to the overcurrent capacity of the MOS device of the electric regulation circuit;

[0043] Determine a phase current protection threshold Ip according to the phase current threshold Ia and the overcurrent threshold Ib;

[0044] Collect the current phase current Ic;

[0045] Compare the current phase current Ic with the phase current protection threshold Ip;

[0046] If the current phase current Ic exceeds the phase current protection threshold Ip, the PWM chopping output in the current cycle is turned off.

[0047] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0048] The present invention realizes dual current protection by real-time monitoring of bus current and phase line current, accurately controls the starting current of the electric regulator, avoids the occurrence of overcurrent or overtemperature, and thus greatly improves the safety of the electric regulator;

[0049] The present invention adjusts the throttle value in real time according to the actual load and rotation speed of the motor, so that the electric regulator can provide the best torque output under different loads and ensure the safety of the starting process. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0051] Figure 1 is a flow chart of an interrupt mode at the end of a PWM chopping cycle according to an embodiment of the present invention;

[0052] Figure 2 This is a flow chart of over-current protection during a PWM chopping cycle in an embodiment of the present invention;

[0053] Figure 3 Flow chart of bus overcurrent protection in an embodiment of the present invention;

[0054] Figure 4 A schematic diagram showing the implementation principle of a BLDC electric speed controller intelligent startup protection control method in another embodiment of the present invention. DETAILED DESCRIPTION

[0055] 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.

[0056] The BLDC electric speed controller intelligent startup protection control method disclosed in this embodiment includes the following steps:

[0057] The phase current threshold Ia is preset according to the continuous current carrying capacity of the power MOSFET body diode of the MOS device of the electric adjustment circuit, and the overcurrent threshold Ib is preset according to the overcurrent capacity of the MOS device of the electric adjustment circuit. In this embodiment, the phase current threshold Ia is 0.8 times the maximum freewheeling capacity of the body diode of the MOS device of the electric adjustment circuit. The overcurrent threshold Ib is 0.8 times the overcurrent capacity of the MOS device of the electric adjustment circuit when it is turned on. Of course, in other embodiments, the phase current threshold Ia can also be other multiples (less than 1) of the maximum freewheeling capacity of the body diode of the MOS device of the electric adjustment circuit; the overcurrent threshold Ib can also be other multiples (less than 1) of the overcurrent capacity of the MOS device of the electric adjustment circuit when it is turned on.

[0058] The phase current protection threshold Ip is determined according to the phase current threshold Ia and the overcurrent threshold Ib.

[0059] It should be noted that during the startup phase, since the motor speed is low and it is still in the strong drive stage, turning on the PWM chopping interrupt does not have much impact on the drive performance.

[0060] like Figure 1 As shown in Figure 1, the interrupt mode is entered at the end of the PWM chopping cycle, including the following steps:

[0061] S11, collecting the current phase current Ic.

[0062] S12. Compare the current phase current Ic with the phase current protection threshold Ip.

[0063] S13. Determine the maximum duty cycle PWMmax of the PWM signal according to the comparison result between the current phase current Ic and the phase current protection threshold Ip.

[0064] S14: Compare the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal to determine the duty cycle of the actual output PWMout of the ESC.

[0065] The steps of determining the maximum duty cycle PWMmax of the PWM signal according to the comparison result of the current phase current Ic and the phase current protection threshold Ip are specifically as follows:

[0066] Compare the current phase current Ic with the phase current protection threshold Ip;

[0067] If the current phase current value Ic exceeds the phase current protection threshold Ip, the maximum duty cycle PWMmax of the PWM signal is reduced.

[0068] If the current phase current value Ic is less than K times the phase current protection threshold Ip, the maximum duty cycle DutyMax of the PWM signal continues to increase. It should be noted that since the current phase current value Ic is detected continuously in real time, if the current phase current value Ic is less than K times the phase current protection threshold Ip, the maximum duty cycle DutyMax of the PWM signal is continuously increased with a certain duty cycle step.

[0069] If it is greater than or equal to K times the phase current protection threshold Ip and less than or equal to the phase current protection threshold Ip, the maximum duty cycle DutyMax of the current PWM signal is kept unchanged.

[0070] Wherein, K is a constant greater than 0 and less than 1. In this embodiment, the constant K is 2 / 3. Of course, in other embodiments, the constant K can also be other values ​​greater than 0 and less than 1.

[0071] The duty cycle of the PWMin input controlled by the user is DutyIn; the duty cycle of the PWMout actually output by the ESC is DutyOut.

[0072] The steps of comparing the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal to determine the duty cycle DutyOut of the actual output PWMout of the ESC are as follows:

[0073] Compare the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal;

[0074] If the duty cycle DutyIn of the user-controlled input PWMin is less than the maximum duty cycle DutyMax of the PWM signal, the duty cycle of the actual output PWMout of the ESC is DutyIn.

[0075] If the duty cycle DutyIn of the user-controlled input PWMin is greater than the maximum duty cycle DutyMax of the PWM signal, the duty cycle of the actual output PWMout of the ESC is DutyMax.

[0076] In this embodiment, the step of determining the phase current protection threshold Ip according to the phase current threshold Ia and the overcurrent threshold Ib includes: in the motor startup stage, judging the driving mode of the electric regulator; if the electric regulator adopts the synchronous rectification (upper and lower bridge complementary chopping) driving mode, the overcurrent threshold Ib is used as the phase current protection threshold Ip; if the electric regulator adopts the asynchronous rectification driving mode, the phase current threshold Ia is used as the phase current protection threshold Ip. It should be noted that the driving mode is controlled by the electric regulator itself, and the method for judging the driving mode of the electric regulator is a prior art and will not be repeated here.

[0077] It should be noted that, since the phase current is constantly increasing during the PWM signal conduction phase, if the phase current is collected every time the PWM signal is turned off, there is still a risk of overcurrent during the conduction phase when the duty cycle is relatively long. Therefore, the present invention has been further optimized, and on the basis of the above logic, an overcurrent protection strategy is added during the chopping cycle. To this end, the BLDC electric speed control intelligent startup protection control method of the present invention is further optimized as follows:

[0078] The BLDC electric speed controller intelligent startup protection control method of this embodiment also includes the step of performing overcurrent protection during the PWM chopping cycle. Figure 2 As shown, the details are as follows:

[0079] Step S21, setting the ADC voltage threshold Vmax to the actual ADC value Vp corresponding to the current phase current protection threshold Ip through the ADC, that is, Vmax=Vp;

[0080] Step S22, collecting the phase current Ic of the motor in real time through the ADC, calculating the current ADC voltage Vc corresponding to the phase current Ic, and determining whether the current ADC voltage Vc is greater than the voltage threshold Vmax;

[0081] Step S23: If the current ADC voltage Vc is greater than the voltage threshold Vmax, the PWM chopping output of the current cycle of the actual output PWMout of the electric regulator is turned off, otherwise, continue to execute step S22.

[0082] In this embodiment, the BLDC electric speed controller intelligent startup protection control method further includes a bus overcurrent protection step. Figure 3 As shown in the figure, the busbar overcurrent protection steps include:

[0083] Step S31, presetting the maximum bus current Imax;

[0084] Step S32, real-time detection of the current bus current Im;

[0085] Step S33, determining whether the current bus current Im is greater than the preset maximum bus current Imax;

[0086] Step S34: if the current bus current Im is greater than the preset maximum bus current Imax, the PWM signal output is turned off.

[0087] The present invention detects phase line current information in real time during the chopping cycle, and detects the output of the motor in real time according to the phase current information. Once it is detected that the output of the electric regulator exceeds the threshold, the output is stopped immediately, thereby achieving real-time protection for the electric regulator.

[0088] The present invention combines the real-time detection of the motor speed to dynamically adjust the throttle value output by the ESC (i.e. dynamically adjust the duty cycle of the actual output PWMout of the ESC). Through this method, even if the motor load is large, the ESC can output the maximum torque without exceeding the safety range, thereby providing better starting performance.

[0089] In addition, since the present invention can make adjustments based on real-time detected information such as bus current, phase line current and rotation speed, it can adapt to the differences in resistance and inductance of different motors, ensuring that different types of motors can be effectively protected during the startup process.

[0090] In another embodiment, if Figure 4 As shown, the BLDC electric speed controller intelligent startup protection control method includes the following steps:

[0091] The phase current threshold Ia is preset according to the continuous current carrying capacity of the power MOSFET body diode of the MOS device of the electric regulation circuit, and the overcurrent threshold Ib is preset according to the overcurrent capacity of the MOS device of the electric regulation circuit.

[0092] The phase current protection threshold Ip is determined according to the phase current threshold Ia and the overcurrent threshold Ib. It should be noted that in practice, the phase current protection threshold Ip needs to be converted into a voltage protection threshold Vb (calculated according to the resistance Rb of the current sampling resistor and the phase current protection threshold Ip).

[0093] The current phase current Ic is collected; the current voltage Vo is calculated based on the current phase current Ic and the sampling resistor.

[0094] The voltage protection threshold Vb and the current voltage Vo are input into the comparator for comparison; the current voltage Vo and the voltage protection threshold Vb are compared by the comparator; if the current voltage Vo exceeds the voltage protection threshold Vb (that is, the current phase current Ic exceeds the phase current protection threshold Ip), the PWM chopping output in the current cycle is turned off. For example, when the chopping output of the PWM signal in the current cycle only reaches 40% (assuming that the maximum duty cycle of the PWM signal is 50%), the current voltage Vo has exceeded the voltage protection threshold Vb, and the PWM chopping output in the current cycle is turned off (that is, the chopping output of the PWM signal in the current cycle only reaches 40%, and the chopping of the current cycle is no longer output).

[0095] The present invention detects the phase current in real time, and when the phase current exceeds the protection threshold, shuts off the PWM chopping output in the current cycle to achieve electrical regulation protection.

[0096] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. BLDC electric speed controller intelligent startup protection control method, characterized in that: The following steps are involved: The phase current threshold Ia is preset according to the continuous current carrying capacity of the power MOSFET body diode of the MOS device of the electric regulation circuit, and the overcurrent threshold Ib is preset according to the overcurrent capacity of the MOS device of the electric regulation circuit; Determine a phase current protection threshold Ip according to the phase current threshold Ia and the overcurrent threshold Ib; Entering interrupt mode at the end of the PWM chopping cycle: Collect the current phase current Ic; Compare the current phase current Ic with the phase current protection threshold Ip; Determine the maximum duty cycle PWMmax of the PWM signal according to the comparison result between the current phase current Ic and the phase current protection threshold Ip; The duty cycle DutyIn of the user-controlled input PWMin is compared with the maximum duty cycle DutyMax of the PWM signal to determine the duty cycle of the actual output PWMout of the ESC.

2. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: The step of determining the maximum duty cycle PWMmax of the PWM signal according to the comparison result of the current phase current Ic and the phase current protection threshold Ip is specifically as follows: Compare the current phase current Ic with the phase current protection threshold Ip; If the current phase current value Ic exceeds the phase current protection threshold Ip, the maximum duty cycle PWMmax of the PWM signal is reduced; If the current phase current value Ic is less than K times the phase current protection threshold Ip, the maximum duty cycle DutyMax of the PWM signal continues to increase; If it is greater than or equal to K times of the phase current protection threshold Ip and less than or equal to the phase current protection threshold Ip, the maximum duty cycle DutyMax of the current PWM signal is kept unchanged; Wherein, K is a constant greater than 0 and less than 1.

3. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: The step of comparing the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal to determine the duty cycle DutyOut of the actual output PWMout of the ESC is specifically as follows: Compare the duty cycle DutyIn of the user-controlled input PWMin with the maximum duty cycle DutyMax of the PWM signal; If the duty cycle DutyIn of the user-controlled input PWMin is less than the maximum duty cycle DutyMax of the PWM signal, the duty cycle of the actual output PWMout of the ESC is DutyIn; If the duty cycle DutyIn of the user-controlled input PWMin is greater than the maximum duty cycle DutyMax of the PWM signal, the duty cycle of the actual output PWMout of the ESC is DutyMax.

4. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: The step of determining the phase current protection threshold Ip according to the phase current threshold Ia and the overcurrent threshold Ib includes: in the motor startup phase, judging the driving mode of the electric regulator; if the electric regulator adopts a synchronous rectification driving mode, the overcurrent threshold Ib is used as the phase current protection threshold Ip; if the electric regulator adopts a non-synchronous rectification driving mode, the phase current threshold Ia is used as the phase current protection threshold Ip.

5. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: Also included is the step of performing over-current protection during the PWM chopping cycle; The steps of performing over-current protection within the PWM chopping cycle include: Step S21, setting the ADC voltage threshold Vmax to the actual ADC value Vp corresponding to the current phase current protection threshold Ip through the ADC, that is, Vmax=Vp; Step S22, collecting the phase current Ic of the motor in real time through the ADC, calculating the current ADC voltage Vc corresponding to the phase current Ic, and determining whether the current ADC voltage Vc is greater than the voltage threshold Vmax; Step S23: If the current ADC voltage Vc is greater than the voltage threshold Vmax, the PWM chopping output of the current cycle of the actual output PWMout of the electric regulator is turned off, otherwise, continue to execute step S22.

6. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: The constant K is 2 / 3.

7. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: The phase current threshold Ia is 0.8 times the maximum freewheeling capability of the body diode of the MOS device of the electric regulation circuit.

8. The BLDC electric speed controller intelligent startup protection control method according to claim 1 is characterized in that: The overcurrent threshold Ib is 0.8 times the overcurrent capacity of the MOS device of the electric control circuit when it is turned on.

9. The BLDC electric speed controller intelligent startup protection control method according to claim 1, characterized in that: The busbar overcurrent protection step is also included, and the busbar overcurrent protection step includes: Preset the maximum bus current Imax; Real-time detection of current bus current Im; Determine whether the current bus current Im is greater than the preset maximum bus current Imax; If the current bus current Im is greater than the preset maximum bus current Imax, the PWM signal output is turned off.

10. BLDC electric speed controller intelligent startup protection control method, characterized in that: The following steps are involved: The phase current threshold Ia is preset according to the continuous current carrying capacity of the power MOSFET body diode of the MOS device of the electric regulation circuit, and the overcurrent threshold Ib is preset according to the overcurrent capacity of the MOS device of the electric regulation circuit; Determine a phase current protection threshold Ip according to the phase current threshold Ia and the overcurrent threshold Ib; Collect the current phase current Ic; Compare the current phase current Ic with the phase current protection threshold Ip; If the current phase current Ic exceeds the phase current protection threshold Ip, the PWM chopping output in the current cycle is turned off. The protection voltage Vb is determined according to the phase current protection threshold Ip.

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