Foshan inverter | Inverter Price | any of factory outlets, any group of professional inverter manufacturers, quality assurance and affordable. Inverter works mainly by the rectifier (AC to DC), filtered again rectifier (DC-AC), braking unit, drive unit, a detection unit composed of micro-processing unit. 1. Why is the rotational speed of the motor can be freely changed? * 1: r / min motor rotation speed unit: the number of rotations per minute, can also be expressed as rpm, for example: 2-pole motor 50Hz3000 [r / min] 4-pole motor 50Hz1500 [r / min] Conclusion: the rotational speed of the motor with frequency Motor proportional referred to herein as AC induction motor, the motor most used in the industry are of this type motor. AC induction motor (hereinafter referred to as motor) approximately correct rotation speed depending on the number of poles and frequency of the motor. Depending on the operating principle of the motor in the number of poles is fixed. Since the pole is not a continuous numeric value (a multiple of 2, for example, the number of poles 2,4,6), it is generally unwell and by changing the value to adjust the speed of the motor. In addition, the frequency can be adjusted on the outside of the motor and then supplied to the motor, the rotation speed of the motor so it can be free of control. Therefore, for the purpose of controlling the frequency inverter, motor speed control device is used as the preferred device. n = 60f / pn: synchronous speed f: power frequency p: Motor poles Conclusion: changing the frequency and voltage motor control method is best only if you change the frequency without changing the voltage, frequency reduction causes the motor for overvoltage (over-excitation), resulting in the motor may be burned. Therefore, changing the frequency of the inverter and must be simultaneously changing the voltage. When the output frequency above the rated frequency, voltage can not continue to increase, the highest is only equal to the rated motor voltage. For example: the rotational speed of the motor in order to halve the output frequency change from 50Hz to 25Hz, then the output voltage of the inverter is required to change from 400V to about 200V 2. When the motor rotation speed (frequency) changes its output torque will happen? * 1: frequency power supplied from the grid power supply (commercial power supply) * 2: starting current when the motor starts running, the starting torque and the maximum torque output current of the inverter drive when the drive frequency is less than the direct employment Power drive motor started at a frequency power supply and accelerate a big impact, and when using the inverter power supply, the impact would be weaker. Direct starting frequency will produce a large starting starting current. When using the inverter output voltage and frequency of the inverter is gradually applied to the motor, so the motor starting currents and impact to be smaller. Typically, the torque generated by the motor to reduce the frequency with (speed reduction) decreases. The actual data is reduced in some drive manual gives instructions. By using the drive flux vector control, will improve the insufficient torque at low speed motor, even at low speeds the motor can also be output sufficient torque. 3. When the inverter speed to greater than 50Hz frequency, the output torque of the motor will reduce the normal voltage motors are designed and manufactured according to 50Hz, the rated torque is within this voltage range is given. Thus the governor under the rated frequency is called constant torque speed. (T = Te, P <= Pe) the output frequency is greater than 50Hz frequency, the torque generated by the motor to be inversely proportional to the frequency of the linear relationship and decline. When the motor speed greater than 50Hz frequency operation, the motor size of the load must be taken into account to prevent insufficient motor output torque. For example, when the torque generated by the motor to be reduced to about 100Hz when the torque generated 50Hz 1/2. So speed above the nominal frequency is called constant power speed. (P = Ue * Ie) 4. Drive 50Hz or more applications you know, for a particular motor, the rated voltage and rated current unchanged. Such as the inverter and motor ratings are: 15kW / 380V / 30A, the motor can operate at 50Hz or more. When the speed of 50Hz, the output voltage of the inverter is 380V, the current is 30A. At this time, if the output frequency is increased to 60Hz, the inverter maximum output voltage and current can only to 380V / 30A. It is clear that the output power constant. So we call this time of constant power speed torque situation how it because P = wT.?. (w: angular velocity, T: torque) because P constant, w is increased, the torque is reduced accordingly . We can also find another perspective: the motor stator voltage U = E + I * R (I is the current, R is