Switch electro-hydraulic proportional amplifier(PA) widely employs single switch modulation power driving(SSMPD) or reverse discharging power driving(RDPD) at present.SSMPD has slow dynamic response,and can't adjust independently the dither signal's amplitude and frequency;RDPD accelerates the current decay;consequently,it increases current ripple and power loss.For the purpose of solving the above mentioned problem,the tri-state modulation power driving(TSMPD) scheme was proposed for improving the performance of power driving.Detailedly,the hardware circuit for the tri-state modulation power driving is designed;the tri-state modulation algorithm is realized by digital signal processor(DSP).The tri-state modulation power driving is investigated by experiments,comparetive experiments among the single switch modulation power driving(SSMPD),reverse discharging power driving(RDPD),and the TSMPD are implemented,and the experimental results demonstrate that the linearity error of TSMDP meets the requirement of PA;the current response of TSMSP is the best;the amplitude of ripple current of the TSMPD can be reduced without increasing frequency of PWM,in addition,dither signal amplitude and frequency can be adjusted independently for each other.It is very meaningful to guide the development of high performance proportional amplifier for high frequency response proportional solenoid.
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