A Calculation Method of Control Parameters of Permanent Magnet Motor Based on Variable Switching Frequency

Abstract

The invention provides a variable-switching-frequency-based method for calculating a control parameter of a permanent-magnet motor. On the basis of comprehensive consideration of a relationship between a switching frequency and a motor control performance and a power tube switching characteristic, a speed regulating range of a motor is divided into an intermediate-low speed section and an intermediate-high speed section. At the intermediate-low speed section, a constant switching frequency is employed; and at the intermediate-high speed section, a switching frequency and a corresponding control parameter are calculated in real time according to a motor rotating speed and motor controlling of the switching frequency is realized by changing a TBPRD value of a period register of a pulse width modulation module of a microcontroller, so that the number of times of usage of currents and positions within an electric period at a motor high-speed section can be increased. Therefore, a good tracking effect of a circular magnetic field can be realized and the control precision and the torque output performance of the permanent-magnet speed-regulating motor are improved.

Description

technical field [0001] The invention belongs to the technical field of motor control, in particular to a method for calculating control parameters of permanent magnet motors based on variable switching frequency. Background technique [0002] The use of voltage space vector modulation (SVPWM) technology to control permanent magnet motors regards the inverter and the motor as one, and obtains a circular rotating magnetic field by controlling the voltage vector to achieve excellent control effects. In the vector control process, the switching frequency of the power tube in the permanent magnet motor control system is also called the control frequency. When the value TBPRD in the period register of the pulse modulation module in the microcontroller is fixed, the switching frequency is also determined accordingly. for where TBCLK is the base clock period of the enhanced microcontroller. Since the permanent magnet motor vector control generates the power tube switch signal aft...

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Problems solved by technology

However, the modification of the switching frequency will affect the control parameters of the system, mainly the speed loop PI controller proportional factor k sp , integral factor k si and current loop PI controller scaling factor k cp , integral factor k ci ; In addition, in the process of improving the system control performance by increasing the switching frequency, the upper limit switching frequency f of the power tube should be considered max It will be limited by the current and cannot be increased without limit, otherwise it will cause unsafe consequences such as the power tube being burned

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