Brushless DC motor braking system and method

A brushless DC motor braking method performed by a brushless DC motor braking system, comprising:

• a brushless DC motor braking with duty cycle of PWM modulation signals of three upper transistors of a three-phase inverter as zero and duty cycle of PWM modulation signals of three lower transistors of the three-phase inverter as an initial duty cycle of the PWM modulation signals;
• converting an analog voltage signal sampled by a voltage sampling module into a digital voltage signal through an ADC module during a braking process, wherein the digital voltage signal is a busbar voltage value;
• determining whether the busbar voltage value is between a high threshold of the busbar voltage and a low threshold of the busbar voltage in real time through a computing module;
• in response to the busbar voltage value triggering the high threshold of the busbar voltage, a PWM modulation module outputting PWM modulation signals with duty cycle of all six switch transistors of the three-phase inverter being zero;
• in response to the busbar voltage value triggering the low threshold of the busbar voltage, the PWM modulation module outputting PWM modulation signals with duty cycle of the PWM modulation signals of the three upper transistors of the three-phase inverter being zero and duty cycle of the PWM modulation signals of the three lower transistors of the three-phase inverter being the initial duty cycle of the PWM modulation signals;
• during a slow braking process of the brushless DC motor, in response to the busbar voltage value triggering the high threshold of the busbar voltage NO times within a duration time TO, the PWM modulation module outputting PWM modulation signals with decreasing duty cycle to the three lower transistors of the three-phase inverter;
• in response to the busbar voltage value triggering the low threshold of the busbar voltage NO times within the duration time TO, the PWM modulation module outputting PWM modulation signals with increasing duty cycle to the three lower transistors of the three-phase inverter;
• and
• controlling the busbar voltage value to be between the high threshold of the busbar voltage and low threshold of the busbar voltage through a brake control module, for controlling the brushless DC motor to perform slow braking until stopping;
• or
• the brushless DC motor braking method comprises:
• a brushless DC motor braking with duty cycle of the PWM modulation signals of three upper transistors of a three-phase inverter as zero and duty cycle of the PWM modulation signals of three lower transistors of the three-phase inverter as an initial duty cycle of the PWM modulation signals;
• converting an analog voltage signal sampled by a voltage sampling module into a digital voltage signal through an ADC module during a braking process, wherein the digital voltage signal is a busbar voltage value;
• determining whether the busbar voltage value is between a high threshold of the busbar voltage and a low threshold of the busbar voltage in real time through a computing module;
• in response to the busbar voltage value triggering the high threshold of the busbar voltage, a PWM modulation module outputting PWM modulation signals with duty cycle of all six switch transistors of the three-phase inverter being zero;
• in response to the busbar voltage value triggering the low threshold of the busbar voltage, the PWM modulation module outputting PWM modulation signals with duty cycle of the three upper transistors of the three-phase inverter being zero and duty cycle of the three lower transistors of the three-phase inverter being the initial duty cycle of the PWM modulation signals;
• in response to the number of times the busbar voltage value triggering the high threshold of the busbar voltage within a duration time T1 being greater than a high threshold N2 of the number of times, the PWM modulation module outputting PWM modulation signals with the gradual decreasing duty cycle to three lower transistors of the three-phase inverter, until the number of times the busbar voltage value triggering the high threshold of the busbar voltage within the duration time T1 is between the low threshold N1 of the number of times and the high threshold N2 of the number of times;
• in response to the number of times the busbar voltage value triggering the high threshold of the busbar voltage within the duration time T1 being less than a low threshold N1 of the number of times, the PWM modulation module outputting PWM modulation signals with the gradual increasing duty cycle to three lower transistors of the three-phase inverter, until the number of times the busbar voltage value triggering the high threshold of the busbar voltage within the duration time T1 is between the low threshold N1 of the number of times and the high threshold N2 of the number of times;
• and
• controlling the busbar voltage value to be between the high threshold of the busbar voltage and low threshold of the busbar voltage through a brake control module, for controlling the brushless DC motor to perform slow braking until stopping.

A brushless DC motor braking system, comprising

• a brushless DC motor, a processor and a memory storing executable instructions of the processor, wherein when the instructions are executed by the processor, the processor is configured to perform:
• braking with duty cycle of PWM modulation signals of three upper transistors of a three-phase inverter as zero and duty cycle of PWM modulation signals of three lower transistors of the three-phase inverter as an initial duty cycle of the PWM modulation signals;
• converting an analog voltage signal into a digital voltage signal through an ADC module during a braking process, wherein the digital voltage signal is a busbar voltage value;
• determining whether the busbar voltage value is between a high threshold of the busbar voltage and a low threshold of the busbar voltage in real time;
• in response to the busbar voltage value triggering the high threshold of the busbar voltage, outputting PWM modulation signals with duty cycle of all six switch transistors of the three-phase inverter being zero;
• in response to the busbar voltage value triggering the low threshold of the busbar voltage, outputting PWM modulation signals with duty cycle of the PWM modulation signals of the three upper transistors of the three-phase inverter being zero and duty cycle of the PWM modulation signals of the three lower transistors of the three-phase inverter being the initial duty cycle of the PWM modulation signals;
• during a slow braking process of the brushless DC motor, in response to the busbar voltage value triggering the high threshold of the busbar voltage N0 times within a duration time T0, outputting PWM modulation signals with decreasing duty cycle to the three lower transistors of the three-phase inverter;
• in response to the busbar voltage value triggering the low threshold of the busbar voltage N0 times within the duration time T0, outputting PWM modulation signals with increasing duty cycle to the three lower transistors of the three-phase inverter;
• and
• controlling the busbar voltage value to be between the high threshold of the busbar voltage and low threshold of the busbar voltage, for controlling the brushless DC motor to perform slow braking until stopping;
• or
• the processor is configured to perform:
• braking with duty cycle of the PWM modulation signals of three upper transistors of a three-phase inverter as zero and duty cycle of the PWM modulation signals of three lower transistors of the three-phase inverter as an initial duty cycle of the PWM modulation signals;
• converting an analog voltage signal into a digital voltage signal through an ADC module during a braking process, wherein the digital voltage signal is a busbar voltage value;
• determining whether the busbar voltage value is between a high threshold of the busbar voltage and a low threshold of the busbar voltage in real time;
• in response to the busbar voltage value triggering the high threshold of the busbar voltage, a PWM modulation module outputting PWM modulation signals with duty cycle of all six switch transistors of the three-phase inverter being zero;
• in response to the busbar voltage value triggering the low threshold of the busbar voltage, outputting PWM modulation signals with duty cycle of the three upper transistors of the three-phase inverter being zero and duty cycle of the three lower transistors of the three-phase inverter being the initial duty cycle of the PWM modulation signals;
• in response to the number of times the busbar voltage value triggering the high threshold of the busbar voltage within a duration time T1 being greater than a high threshold N2 of the number of times, outputting PWM modulation signals with the gradual decreasing duty cycle to three lower transistors of the three-phase inverter, until the number of times the busbar voltage value triggering the high threshold of the busbar voltage within the duration time T1 is between the low threshold N1 of the number of times and the high threshold N2 of the number of times;
• in response to the number of times the busbar voltage value triggering the high threshold of the busbar voltage within the duration time T1 being less than a low threshold N1 of the number of times, outputting PWM modulation signals with the gradual increasing duty cycle to three lower transistors of the three-phase inverter, until the number of times the busbar voltage value triggering the high threshold of the busbar voltage within the duration time T1 is between the low threshold N1 of the number of times and the high threshold N2 of the number of times;
• and
• controlling the busbar voltage value to be between the high threshold of the busbar voltage and low threshold of the busbar voltage, for controlling the brushless DC motor to perform slow braking until stopping.