Sensor-less three-stage type starting method for deep well piston pump and application thereof

Abstract

The invention discloses a sensor-less three-stage type starting method for a deep well piston pump. The piston pump is driven by a direct-current brushless motor, and the starting method includes the following steps that S1, the current position of a rotor is determined based on short-time pulse detection and positioning, and an inverter is controlled according to a controlling strategy corresponding to the position; S2, the step S1 is repeated until revolving speed reaches a first threshold value; S3, the reversing moment is determined based on a pulse width modulation stator current slope, and at the reversing moment, a control strategy of a next sector is used for controlling the inverter; S4, the step S3 is repeated until the revolving speed reaches a second threshold value which is larger than the first threshold value; S5, the reversing moment is determined based on back electromotive force zero passing point detection, and at the reversing moment, a control strategy of a next sector is used for controlling the inverter. The starting method can be used for a high-lift photovoltaic water pumping system and can improve the success rate of starting the system.

Description

technical field [0001] The present invention relates to a method for starting a deep well piston pump system based on a DC brushless motor, more specifically, a three-stage starting method for a deep well piston pump without a position sensor, and the application of the starting method to a high-lift photovoltaic pumping system , belongs to the technical field of electric drive control. Background technique [0002] Photovoltaic pumping is an important form of solar energy utilization. It can efficiently solve the problem of domestic and production water in remote areas, generate good economic and social benefits, and has broad application prospects. [0003] Such as figure 1 As shown, the photovoltaic pumping system consists of a photovoltaic array 1 , an inverter controller (inverter for short) 2 and a water pump 3 . Photovoltaic array 1 converts solar radiation energy into electrical energy. As the DC power supply of the system, inverter controller 2 controls the speed ...

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Problems solved by technology

[0004] However, the piston pump presents a constant torque load characteristic. When the high-lift system is started, it must output a sufficiently high starting torque to overcome the pressure generated by the accumulated water in the pumping pipe. Therefore, the starting and low-speed operation characteristics of the motor and controller are required. high

Specifically, the following two problems need to be solved: first, reduce the starting current as much as possible under the premise of ensuring a sufficiently high starting torque, and prevent short-term overcurrent from causing damage to the controller and the permanent magnet of the motor; second, the photovoltaic pumping system When starting in the morning, the incident solar radiation intensity of the photovoltaic array is weak, and the electric energy that can be provided is limited. If the starting power is too large, the output voltage of the photovoltaic array will drop, resulting in failure to start

For example, the short-time pulse method, the frequency increase current limiting method, the stator current slope threshold judgment method, etc., but there are still problems of low load capacity and inaccurate control switching, and the effect is not ideal in the application of high-lift photovoltaic pumping systems. Improve

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