Impact starting method and system for brushless direct current motor of electric tool

Abstract

The invention discloses an impact starting method and system for a brushless direct current motor of an electric tool. The starting method comprises the following steps: (10) starting state determination: judging whether a starting working state area of the motor indicates a normal starting state or a stalling state according to the rotation speed of the motor in a starting process; (20) constant-current starting: when the motor is in the normal starting state, using continuous current, of which the upper limit is constant within a cycle, to control starting of the motor; and (30) pulse-current starting: when the motor is in the stalling state, using segmented pulse current to control the starting of the motor. The starting system comprises an inverter (2) electrically connected with the motor (1), a position sensor (3) placed on an end cover of the motor (1), and a controller (4) electrically connected with both the inverter (2) and the position sensor (3). The impact starting methodand system for the brushless direct current motor of the electric tool provided by the invention has the advantages that higher power levels of components are avoided, a switching tube is unlikely tobe damaged, and a low heating value of a motor winding is achieved.

Description

technical field [0001] The invention belongs to the technical field of starting control of brushless DC motors, in particular to an impact starting method and system for brushless DC motors of electric tools without increasing the power level of components and parts, without damage to switch tubes, and with low calorific value of motor windings. Background technique [0002] Power tools use a large number of brushless DC motors. [0003] The traditional brushless DC motor control adopts the fixed chopping limit method, which is to draw up the current chopping limit according to the load characteristics. In a single commutation cycle, the current remains continuous. This control method can generate relatively smooth electromagnetic torque to drive the load, and has high efficiency and small torque ripple during normal operation. However, since the power tool is often stalled, it is necessary for the brushless DC motor of the power tool to have a torque exceeding the rated va...

AI Technical Summary

Problems solved by technology

But this will greatly increase the product volume and increase the manufacturing cost

[0005] Therefore, the problems existing in the prior art are: due to the large locked-rotor current of the brushless DC motor of the electric tool, the problem of damage to the switch tube and excessive heat generation of the motor winding will be caused without increasing the components.

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