When using a motor with an encoder by performing auto tuning, you need to choose the operation mode or continuous operation mode depending on the application.
1. Cycle operation modeThis mode prioritizes the maximum short-time torque generation in the high-speed range and allows for 150% of the maximum short-time torque over the entire speed range. However, since 150% motor torque is generated at 1800 r/min even when the vector inverter output voltage is lower than the commercial power supply, the input current is larger than the continuous operation mode when generating the same torque. Therefore, the motor temperature goes high and it is difficult to continuously operate at 100% torque. Temperature rise is suppressed by using the motor at 50% ED torque. This mode is suitable for an application that requires large torque momentarily, such as lift machine.
2. The continuous operation mode prioritizes generation of continuous maximum torque in the low-speed range. To enable continuous operation at 100% torque, motor temperature must be suppressed under the standard value. When continuous torque is generated, the excitation current and torque current are controlled so that the motor input current matches the rated motor current and limit the motor input current to the rated current. This enables continuous operation at a wide low speed range up to 600 r/min. (100% continuous operation below 600 r/min is not possible because the standard motor cools itself by its fan and the cooling ability is decreased at low-speed range.) Note that by controlling the motor input current within the rated current, undervoltage occurs around the rated speed because the vector inverter output voltage is low, and it is not possible to generate 150% of the maximum short-time torque. This mode is suitable for an application that requires continuous torque, such as line control. Figure 1