ZFeng 900 Series 560Kw-T-G General Vector Variable Frequency Drive
The high-power frequency converter developed and produced by our company precisely controls the speed of three-phase AC motors by changing the frequency and voltage of the power supply. Its core lies in the three major links of rectification inverter control.
- Rectification: Convert alternating current into direct current
Input stage: The frequency converter receives three-phase AC power (such as 380V/50Hz) and converts it into pulsating DC power through a rectifier bridge (composed of high-power diodes or thyristors).
Filtering stage: After being filtered by capacitors, pulsating DC power becomes a stable DC bus voltage (approximately 540V, based on 380V input).
Analogy: Comparing alternating current to "waves", rectifiers "flatten" the waves into "flat current" (direct current).
- Inverter: Convert direct current into adjustable frequency alternating current
Core components: Using IGBT (Insulated Gate Bipolar Transistor) or SiC (Silicon Carbide) power modules, direct current is chopped into PWM (Pulse Width Modulation) signals through high-frequency switches (usually several thousand to tens of kilohertz).
Frequency control: By adjusting the switching frequency and duty cycle of IGBT, generate AC power with variable frequency and voltage. For example:
Frequency increase → Motor speed increases
Voltage reduction → adapt to light load conditions
Analogy: Inverters are like "music synthesizers" that "modulate" direct current into alternating current of different tones (frequencies) and volumes (voltages) through quick switching.
- System: Achieving high-precision speed regulation and protection
Control algorithm: Vector Control (FOC): Decompose the motor current into torque and excitation components to achieve independent control, suitable for high dynamic performance requirements.
Direct Torque Control (DTC): Directly controls torque and magnetic flux, with faster response speed but slightly larger torque fluctuations.
Protection function: Built in overload, overvoltage, undervoltage, overcurrent, overheating and other protection mechanisms ensure equipment safety.
Analogy: The control algorithm is like an "intelligent driving system", dynamically adjusting the motor output according to the load demand to ensure smooth operation.
Key technical points
- PWM modulation technology: Generate an approximate sine wave voltage through high-frequency switches to reduce harmonic interference.
- Energy feedback: During braking or deceleration, the energy feedback from the motor is fed back to the grid through an inverter to improve energy efficiency.
- Heat dissipation design: High power frequency converters need to be equipped with water cooling or forced air cooling systems to ensure stable operation of IGBT and other devices at high temperatures.
