| Permanent magnet motor is increasingly widely used in underwater vehicle propeller drive.During operation,the radial vibration of the motor transmits noise to the underwater vehicle through the vehicle shell,which affects the concealment of the underwater vehicle.The low-frequency vibration has large energy transfer,slow attenuation,long propagation distance and strong penetration performance,which is difficult to be absorbed by vibration isolation materials such as acoustic insulation pads and shock absorber.It is also not easy to reduce by motor structure optimization design,so it is necessary to use active control method to suppress the low frequency radial vibration of the motor.Injecting harmonic current into the winding can generate electromagnetic harmonic radial force of the motor,and the harmonic radial vibration caused by it can suppress the original harmonic radial vibration of the motor.Therefore,using harmonic current injection is an effective method to suppress the radial vibration of the motor.This thesis focuses on several key problems in the low frequency vibration of surface mounted three-phase permanent magnet motor.The vibration mechanism analysis and the integrated online suppression control method of low frequency radial vibration based on multi-frequency harmonic current injection of surface mounted three-phase permanent magnet motor are studied.The main research contents are as follows:Aiming at the problem that the control parameters of the traditional harmoni c current injection method are single,this paper proposes a multi-frequency harmonic current injection method with phase sequence,amplitude and phase freely controllable.In order to realize the free control of the three parameters,a multi-frequency harmonic current injection model covering phase sequence,amplitude and phase in a synchronous rotating coordinate system is constructed.Through the closed-loop transfer function of the current loop,the transfer function of the multi-frequency harmonic current injection is inversely derived,and the phase compensation amount is calculated.Finally,a multi-harmonic current injection system with adjustable phase sequence,amplitude and phase was designed,and the effectiveness of the proposed method was verified by prototype experiments.Aiming at the radial vibration of each frequency doubling harmonic generated by space vector control of surface mounted permanent magnet motor,the vibration source analysis is carried out.The armature current harmonic component causing the electromagnetic vibration of each frequency doubling harmonic is analyzed,and the symmetrical frequency doubling harmonic current,asymmetric frequency doubling harmonic current and DC current are pointed out.Combined with the space vector transformation of current and the formula of radial magneto-motive force,the space-time model of radial magneto-motive force of three kinds of current under polar groove modulation is derived.Aiming at the armature current injection of surface-mounted three-phase permanent magnet motor,the mechanism analysis of radial vibration of the motor based on symmetric harmonic current,asymmetric harmonic current and DC current of each octave is proposed.The spatio-temporal model of radial magnetomotive force of the three kinds of current is substituted into the radial force wave model under ideal sinusoidal current.Combined with the vibration(acceleration)formula,the radial vibration(acceleration)model and coupled vibration(acceleration)model of three kinds of current injection were further derived.The correspondence between the frequency,amplitude and phase of the three injected currents and the frequency,amplitude and phase of the harmonic radial vibration is analyzed in detail,which is verified by the prototype experiment.The characteristics of vibration models of three kinds of current injection are analyzed,and the symmetrical frequency doubling harmonic current is determined as the input of the comprehensive vibration suppression control of low frequency radial vibration,and its vibration model is the basis for the design of vibration suppression control method.Aiming at the deficiency that the existing vibration control methods can only suppress the vibration of a single characteristic frequency,a comprehensive suppression method of multi-frequency harmonic radial vibration is proposed in this paper.The mapping relationship between harmonic current amplitude and phase and harmonic radial vibration amplitude is constructed,the main mapping and coupling mapping are divided,and the multi-input multi-output nonlinear dynamic model of harmonic current and harmonic vibration amplitude is established.A model-free adaptive algorithm with variable step size is designed for the pseudo partial derivative estimation of the primary mapping,and an autoregressive decoupling algorithm is used for the pseudo partial derivative estimation of the coupled mapping.To ensure the tracking stability,a sliding mode control method is used.Finally,a surface mounted three-phase permanent magnet motor low frequency radial vibration suppression control system with multi-frequency harmonic current injection is designed,including hardware design and software design.In the experiment,the low-frequency radial vibration below 200 Hz is suppressed,and the prototype is adjusted at180 RPM and 225 RPM respectively.Compared with the ideal sinusoidal current,the amplitude of low-frequency radial vibration of each frequency octave harmonic is decreased by 46.90% and 62.52% on average by using the vibration suppression control method in this paper.The total vibration levels of the low-frequency harmonic radial vibration decreased by13.9% and 7.54%. |
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