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| 摘要: |
| 在三相电机的矢量控制中,反馈电流的值是由电流传感器(TA)直接检测得到的,这就要求至少使用2个电流传感器。提出利用数字信号处理器(DSP)的实时计算功能,采用1个电阻测量3个反馈电流的方法。但是,在空间矢量脉宽调制(SVPWM)技术中,当PWM频率很高时,硬件限制了反馈电流的采样。因此,提出通过扩大PWM的周期解决硬件限制问题,即扩大法。但该方法降低了PWM的输出频率,从而影响电机的控制。又提出另一种改进的方法,即补偿法,该方法在不改变PWM周期的条件下,通过补偿主控周期中的一个PWM周期内用于电流采样的开关变化间隙时间,解决了硬件限制问题。给出了电流采样的硬件电路和补偿法程序流程图,在功率400 W的异步电机做实验结果表明,补偿法比扩大法的应用范围更大、效率更高。 |
| 关键词: 反馈电流测量,数字信号处理器,矢量控制 |
| DOI： |
| 分类号:TM359.4 |
| 基金项目: |
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| Feedback current detection in vector control based on DSP controller |
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ZHAI Xiao-fei ZHANG Jun-hong ZHAO Jing-hong
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| Abstract: |
| In the vector control of three-phase motor,current feedbacks are normally directly measured by CTs(Current Transformers),which needs at least two isolated CTs.To measure three feedback currents indirectly with a resistor and a DSP(Digital Signal Processor)-based real-time controller is proposed.However,when the PWM(Pulse Width Modulation) frequency is too high in SVPWM(Space Vector PWM),the measurement becomes more difficult and even impossible due to hardware limitations.Lengthening method,which lengthens PWM period to avoid hardware limitations,is proposed,but the lowered PWM frequency may result in poor stator flux control.Compensation method,which compensates the time gap between transistor commutations for current sampling in one PWM period without varying the PWM period,is also proposed.Its flowchart and current sampling circuit are offered.Test on a 400 W asynchronous motor shows that the compensation method is more efficient and extensive. |
| Key words: feedback current measurement,DSP,vector control |
