A Sensorless Starting Method of Brushless DC Motor with Large Inertia Rotor

Abstract

The invention discloses a sensorless starting method for a brushless DC motor with a large inertia rotor, comprising the following steps: Step 1, initialization; Step 2, positioning; Step 3, detection; Step 4, calculation; Step 5, starting; In the above step 1, the system is initialized according to the rated current of the motor and the rated current of the driver, and the maximum starting current limit I max ; Wherein in above-mentioned step 2, then continuously inject positioning current twice to motor, current value is less than I max , the duration is 1s, ensuring two successful positionings; the invention adopts two-step positioning and limiting current start to facilitate fast and accurate positioning of the motor, avoiding positioning failure caused by the zero point of the initial position of the motor rotor, and the limiting current ensures The rotor of the motor is dragged to the specified position. At the same time, the starting curve is designed to ensure that the frequency and voltage boost curve is smooth, the motor does not lose synchronization and the angle error between external synchronization and self-synchronization is within 0°-30° electrical angle, and the motor speeds up smoothly.

Description

technical field [0001] The invention relates to the technical field of motor starting methods, in particular to a sensorless starting method for a brushless DC motor with a large inertia rotor. Background technique [0002] When starting a brushless DC motor with a large inertia rotor without a position sensor, a three-stage open-loop start is often used, including three stages of pre-positioning, open-loop frequency boost and synchronous switching. The starting time of brushless DC motors with large inertia rotors is long, the high-frequency interference is large, and the rotor position is difficult to detect at low speeds. Therefore, some traditional three-stage positionless starting methods are difficult to apply to brushless DC motors with large inertia rotors. At present, There are several options for starting a brushless DC motor with a large inertia rotor without a position sensor: one is the high-frequency pulse injection method, which uses high-frequency current to ...

AI Technical Summary

Problems solved by technology

The starting time of brushless DC motors with large inertia rotors is long, the high-frequency interference is large, and the rotor position is difficult to detect at low speeds. Therefore, some traditional three-stage positionless starting methods are difficult to apply to brushless DC motors with large inertia rotors. At present, There are several options for starting a brushless DC motor with a large inertia rotor without a position sensor: one is the high-frequency pulse injection method, which uses high-frequency current to inject the three-phase winding of the motor, and detects the non-conductive phase current to estimate the rotor position; but when using When the motor rotor is required to have a salient pole effect, it is difficult to determine the size and frequency of the injection current of the small armature motor, and the starting parameters need to be determined through multiple offline tests; the second is the closed-loop three-stage starting, but additional current or torque needs to be added The sensor has strong high-frequency current interference during the starting stage, and the current and torque cannot be accurately measured and calculated. In practical use, the detection accuracy is affected, which reduces the success rate; the third is the open-loop three-stage starting, but when in use, the starting time is long, When the load changes, the parameters need to be readjusted, and the starting reliability is poor. Therefore, it is necessary to design a sensorless starting method for brushless DC motors with large inertia rotors.

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