1. Inverter Control Method
The inverter control method is determined by the torque characteristics of the load. The motor's mechanical load torque is governed by the equation: P = Tn / 9550, where P is motor power (kW), T is motor torque (N·m), and n is motor speed (rpm). Based on the relationship between torque and speed, loads can be categorized into three types: constant torque, constant power, and variable torque. When P1300=0, the inverter operates in linear U/F mode, suitable for most constant torque applications. For fans or pumps, set P1300=1 to avoid resonance issues. To prevent system instability, the inverter allows setting jump frequencies (P1091~P1094) with a bandwidth (P1101). When P1300=3, it enters programmable U/F mode, allowing custom frequency and voltage curves for precise control. Vector control mimics DC motor behavior, separating excitation and armature currents for high dynamic response. Options like P1300=20/21 (with/without feedback vector control) or P1300=22/23 (vector torque control) offer enhanced accuracy.
2. Acceleration/Deceleration Time
Acceleration time refers to the time taken for the output frequency to rise from 0 to maximum, while deceleration time is the time to drop back to zero. Proper settings are crucial for smooth motor start-up and stopping. Acceleration should limit stator current to avoid overcurrent trips. During deceleration, energy is returned to the DC bus, increasing its voltage. Deceleration time must be set to avoid overvoltage alarms. Formulas for acceleration and deceleration times involve inertia (Jm+Jl), speed (n), and torques (Tma, Tmb, Tl). Empirical methods also help estimate these values by measuring free braking time and adjusting accordingly.
3. Moment of Inertia Setting
Moment of inertia settings are often overlooked but critical for stable operation. Improper settings can lead to oscillations or alarms. The formula J = T/(dω/dt) relates torque to angular acceleration. Motor and load inertia can be measured by running the motor at low frequencies and recording torque and starting time. Parameters P0341 and P0342 are used to input these values, ensuring accurate speed control.
4. Quick Commissioning
Before using the drive, perform quick commissioning with P0010=1. Input correct motor nameplate data, and adjust overload factor (P0640) if the inverter’s power exceeds the motor’s. In vector control, ensure motor data detection (P1910) is done in a cold state. Set ambient temperature (P0625) if different from 20°C. After commissioning, the inverter will enter “Ready to run†mode once alarm A0541 disappears.
5. Dynamic Buffer Function
This feature compensates for voltage drops by reducing frequency and feeding back energy to maintain operation. Enable it via P2800=1 and set P1245 based on supply voltage. Avoid excessive settings that may disturb normal operation. Configure DC voltage controller (P1240=2) and determine holding speed (P1257) based on selected options (P1256).
6. Load Braking
Rapid deceleration causes regenerative braking, increasing DC bus voltage. The MM440 provides braking resistor functionality to dissipate this energy as heat. Ensure brake limit voltage (P2172) is set correctly, and choose braking resistor resistance and capacity according to guidelines. This prevents damage to both the inverter and the resistor.
7. Torque Boost
Torque boost compensates for reduced torque at low speeds by increasing U/F. Parameters P1310, P1311, and P1312 adjust lift levels, with priority order: P1310 > P1311 > P1312. P1316 defines the end frequency of the lift. Settings must follow a small-to-large principle to avoid magnetic saturation and waveform distortion, which could trigger overcurrent trips.
Proper parameter configuration ensures optimal performance of the frequency converter, enabling the variable speed control system to meet all desired control requirements effectively.
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