Elevator inverrter Basics(a)

   1, what is the frequency?
The elevator inverrter is the use of power semiconductor devices will be the role-off frequency to another frequency power conversion power control devices.
   2, PWM and PAM What is the difference?
PWM is the English Pulse Width Modulation (Pulse Width Modulation) acronym, according to certain rules to change the pulse width of the pulse train to adjust the output volume and a tone waveform by value. PAM is the English Pulse Amplitude Modulation (pulse amplitude modulation) acronym is changed according to certain rules pulse amplitude pulse train, to regulate the output value and a modulation waveform.
   3, voltage-and current-What is the difference?
elevator inverrter main circuit can be divided into two categories: voltage is converted to DC voltage source elevator inverrter AC and DC circuit filter is a capacitive; Current DC current source is converted to AC elevator inverrter, its stone DC circuit filter inductor.
   4, why the elevator inverrter voltage and current proportional to the change?
Induction motor magnetic flux and the torque of the motor and the rotor current flows resulting from the interaction between the rated frequency, if the voltage is fixed and only the lower frequency, then the magnetic flux will be too large, the magnetic circuit saturation, severe The burning motor. Therefore, the frequency and voltage proportional to a change, that is to change the frequency converter output voltage while controlling the motor to maintain a certain flux, to avoid weakening and magnetic saturation phenomenon. This control method is used for fan and pump energy-saving elevator inverrter.
   5, motor drive using frequency power supply, the voltage drop is current increases; For elevator inverrter-driven, if the frequency drops voltage drop, then the current is increased?
Frequency down (low), if the same power output, the current increases, but under certain conditions, the torque current is almost constant.
   6, using the elevator inverrter operation, the motor starting current, starting torque what?
Using elevator inverrter operation, with a corresponding increase in the acceleration of the motor frequency and voltage, the starting current is limited to 150% of rated current (according to different models, 125% to 200%). Labor-frequency power directly when starting current of 6 to 7 times, therefore, will have an impact on the mechanical and electrical. With elevator inverrter drive can smoothly start (start time becomes longer). Starting current for the rated current of 1.2 to 1.5 times the starting torque of 70% to 120% of the rated torque; For enhanced functionality with automatic torque converter, the starting torque of 100% or more, you can start with a full load.
   7, V / f mode What does it mean?
Frequency drops voltage V is also proportional to the decline, the question has been answered four instructions. The ratio between V and f are considered characteristic of the motor determined in advance, usually in the controller memory means (ROM) in that there are several features that can switch or the dial to select.
   8 and proportionate change V and f, the motor torque to change?
Down completely when the frequency is reduced proportionally to the voltage, the impedance becomes smaller as the DC resistance constant, would result in a low torque is generated under a reduced tendency to. Therefore, given the low frequency V / f, the output voltage is increased to make some manner so as to obtain a starting torque, this compensation called enhanced start. Variety of methods can be used, a method of automatically select V / f pattern or adjusting potentiometer and other methods.