PROSOFT MVME-147A 处理器模块低压通用变频输出电压为380~650V，输出功率为0.75~40OkW，工作频率为O ~-400Hz，它的主电路都采用交—直—交电路。其控制方式经历了以下四代。正弦脉宽调制(SPWM)控制方式其特点是控制电路结构简单、成本较低，机械特性硬度也较好，能够满足一般传动的平滑调速要求，已在产业的各个领域得到广泛应用。但是，这种控制方式在低频时，由于输出电压较低，转矩受定子电阻压降的影响比较显著，使输出大转矩减小。另外，其机械特性终究没有直流电动机硬，动态转矩能力和静态调速性能都还不尽如人意，且系统性能不高、控制曲线会随负载的变化而变化，转矩响应慢、电机转矩利用率不高，低速时因定子电阻和逆变器死区效应的存在而性能下降，稳定性变差等。
MVME-147A
因此PROSOFT MVME-147A 处理器模块又研究出矢量控制变频调速。电压空间矢量(SVPWM)控制方式它是以三相波形整体生成效果为前提，以逼近电机气隙的理想圆形旋转磁场轨迹为目的，一次生成三相调制波形，以内切多边形逼近圆的方式进行控制的。经实践使用后又有所改进，即引入频率补偿，能消除速度控制的误差;通过反馈估算磁链幅值，消除低速时定子电阻的影响;将输出电压、电流闭环，以动态的精度和稳定度。但控制电路环节较多，且没有引入转矩的调节，所以系统性能没有得到根本改善。
MVME-147A
The PROSOFT MVME-147A processor module has a low-voltage universal variable frequency output voltage of 380-650V, an output power of 0.75-40kW, and a working frequency of O-400Hz. Its main circuit adopts an AC-DC-AC circuit. Its control method has gone through the following four generations. The sine pulse width modulation (SPWM) control method is characterized by a simple control circuit structure, low cost, and good mechanical hardness, which can meet the smooth speed regulation requirements of general transmission. It has been widely applied in various fields of the industry. However, this control method significantly affects the torque at low frequencies due to the lower output voltage, resulting in a decrease in the output torque due to the stator resistance voltage drop. In addition, its mechanical characteristics are ultimately not as hard as DC motors, and its dynamic torque capability and static speed regulation performance are not satisfactory. Moreover, the system performance is not high, and the control curve will change with changes in load. The torque response is slow, the motor torque utilization rate is not high, and at low speeds, the performance decreases and stability deteriorates due to the presence of stator resistance and inverter dead zone effect.
MVME-147A
Therefore, the PROSOFT MVME-147A processor module has developed vector controlled variable frequency speed regulation. The voltage space vector (SVPWM) control method is based on the overall generation effect of three-phase waveforms, with the aim of approximating the ideal circular rotating magnetic field trajectory of the motor air gap. It generates three-phase modulation waveforms at once and controls them by approaching the circle with inscribed polygons. After practical use, it has been improved by introducing frequency compensation, which can eliminate errors in speed control; Estimate the magnetic flux amplitude through feedback to eliminate the influence of stator resistance at low speeds; Close-loop the output voltage and current to achieve dynamic accuracy and stability. However, there are many control circuit links and there is no introduction of torque regulation, so the system performance has not been fundamentally improved.
MVME-147A
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