Motor V/F curve

In Figure 4-15, curve 1 represents the U/f characteristic of the motor when low-frequency compensation is applied while driving the LXT905LC dynamic constant torque load. Curve 2 shows the U/f characteristic without low-frequency compensation under the same constant torque load condition. Curve 3 illustrates the U/f curve with low-frequency compensation for the motor when it drives a water pump fan load, while curve 4 depicts the U/f curve without low-frequency compensation for the same type of load.

From Figure 4-15, it can also be observed that the motor cannot operate above its rated voltage. Therefore, when the inverter increases the frequency beyond the base frequency (f_i), the output voltage (U) remains constant at the rated level, causing the U/f curve to become a horizontal line. This change reduces the magnetic flux according to equation (4-4). As the magnetic flux decreases, so does the torque, and the motor transitions into a constant power speed control mode. For example, in the case of constant torque speed control where the voltage is fixed, more magnetic flux would typically be required, but this is not possible here due to the voltage limitation. The variation in magnetic flux is illustrated in Figure 4-16.

In Figure 4-16, curve 2 represents the U/f characteristic without low-frequency compensation when the motor is driving a constant torque load. Curve 1 corresponds to the flux variation associated with curve 2. Below the base frequency (f_i), the flux remains constant, corresponding to the constant torque speed control mode. When the frequency exceeds f_i, the flux decreases, and the relationship between voltage and frequency becomes reciprocal, which corresponds to the constant power speed control mode. Curve 4 shows the U/f characteristic without low-frequency compensation when the motor is driving a square torque load. Curve 3 represents the flux variation associated with curve 4. Below f_i, the flux remains relatively constant, corresponding to the square torque speed control mode, while above f_i, the flux changes inversely, again indicating constant power speed regulation.

Multi USB Charger

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Brand Name: OEM

Product Name: Multi USB Charger

Use: Mobile Phone

Place of Origin: Guangdong, China (Mainland)

Port: 6 port

Input: AC100-240V 50/60HZ

Size: 90*70*16mm

Weight: 250g

Materials: PC+ABS

Color: Black/White

Warranty: 1 year

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