Direct torque control method for permanent magnetic synchronous electric machine

Abstract

The invention relates to a direct torque control method for a permanent-magnet synchronous motor, which is characterized in that: based on a flux linkage and torque estimator, the estimated values ofa stator flux linkage and the torque at the present moment are calculated. The error between the estimated value of the torque and a torque reference value is simply adjusted by PI to obtain the dynamic speed difference Delta Omega s of the stator flux linkage and a rotor flux linkage, and then the speed difference Delta Omega s is added with a steady-state rotational speed Omega to obtain total rotational speed of the stator rotational speed. After the total flux linkage rotational speed Omega s<*> is obtained, a specified reference flux linkage vector Psi s<*> in the next sampling period isobtained by referring to a flux linkage computational model. The reference flux linkage vector Psi s<*> and an estimated flux linkage vector Psi s at the present moment are simply calculated to obtainan SVPWM Us<*> which is exerted in the next sampling period. The SVPWM Us<*> is modulated by a space vector modulating method to generate the switching signals of a voltage source inverter. The direct torque control method of the invention has the advantages that as the concept of the space vector is adopted to analyze the mathematical model of PMSM and control the physical quantity thereof, theproblems become especially simple and clear.

Description

technical field [0001] The invention relates to a direct torque control method of a permanent magnet synchronous motor, which is a direct torque control method of a permanent magnet synchronous motor (PMSM) using space vector modulation, and belongs to the technical field of AC motor transmission. Background technique [0002] Direct torque control is a high-performance motor control scheme, which has been relatively maturely applied to asynchronous motors, such as the ACS600 inverter produced by ABB Company, and some literatures apply its control idea to permanent magnet synchronous motors to obtain excellent dynamic characteristics , but there are still the following problems: 1) Since the usual inverter can only generate 6 effective space voltage vectors and 2 zero vectors, only these 6 are used in the switch table of the direct torque control of the permanent magnet synchronous motor 2) When controlling flux linkage and torque at the same time, none of the 8 space voltag...

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Problems solved by technology

[0002] Direct torque control is a high-performance motor control scheme, which has been relatively maturely applied to asynchronous motors, such as the ACS600 inverter produced by ABB Company, and some literatures apply its control idea to permanent magnet synchronous motors to obtain excellent dynamic characteristics , but there are still the following problems: 1) Since the usual inverter can only generate 6 effective space voltage vectors and 2 zero vectors, only these 6 are used in the switch table of the direct torque control of the permanent magnet synchronous motor 2) When controlling flux linkage and torque at the same time, none of the 8 space voltage vectors can accurately satisfy the dual requirements of the system for flux linkage and torque at the same time. 3) Direct torque control uses a hysteresis comparator to implement closed-loop control of torque and flux linkage errors, which will inevitably cause the switching frequency of power devices to be unstable, affecting the The optimal use of switching frequency of power devices, to a certain extent, causes larger flux linkage and torque ripple

However, there are still deficiencies in this technology: 1) Since the switching period of the power device is an integer multiple of the system sampling period, there will be flux linkage and torque errors that exceed the set error range before the control is implemented, that is, the flux linkage and torque cannot be precisely controlled. 2) The content of the switch table still exists and only up to 8 space voltage vectors can be used, which cannot meet the dual requirements of the system for flux linkage and torque at the same time, so the flux linkage and torque ripple are still relatively large

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