Energy saving equipment suppliers remind you that in industrial automation production, the mechanical energy (potential energy, kinetic energy) on the moving load is converted into electrical energy (regenerated electrical energy) through an energy feedback device and sent back to the AC power grid for use by other nearby electrical equipment, so that the motor drive system can reduce the consumption of grid electrical energy per unit time, thereby achieving the goal of energy conservation.
Earlier, the main circuit of energy feedback devices was mostly composed of thyristors and IGBTs. In recent years, some new energy feedback devices have also used intelligent modules such as IPM to simplify the system structure of energy feedback devices.
(1) Thyristor energy feedback device:
The energy feedback main circuit is composed of thyristor devices, which are also relatively early energy feedback devices. They are not only used in frequency converters, but also in the braking of some DC reversible speed control systems.
① Forward working state of universal frequency converter: When the motor is in electric state, the rectifier of the frequency converter is working, while the thyristor device in the energy feedback device is not triggered and is in the cut-off state, and the rectifier is working in the forward direction. The controllable inverter part of the inverter is triggered to work, the uncontrollable reverse rectification part is in the cut-off state, and the inverter is in forward operation.
② Reverse working state of universal frequency converter: When the motor is in the generating state, the rectifier of the frequency converter is in the cut-off state, and the thyristor devices in the energy feedback device are triggered to work. The controllable inverter part of the inverter is still triggered to work, the uncontrollable reverse rectification part is in working state, and the inverter is working in reverse.
(2) IGBT energy feedback device:
The energy feedback main circuit is composed of IGBT devices, which are most commonly used in general frequency converters. The freewheeling diode integrated with IGBT devices cannot be used as a rectifier device due to the limitation of the isolation diode connected to the DC side. Its cost should be higher than that of thyristor energy feedback devices.
① Forward working state of universal frequency converter: When the motor is in electric state, the rectifier of the frequency converter is working, while the IGBT device in the energy feedback device is not triggered and is in the cut-off state, and the rectifier is working in the forward direction. The IGBT devices in the inverter are triggered to work, and the uncontrolled reverse rectification part is in the cut-off state, while the inverter is in forward operation.
② Reverse working state of universal frequency converter: When the motor is in the generating state, the rectifier of the frequency converter is in the cut-off state, and the IGBT device in the energy feedback device is triggered to work. The IGBT devices in the inverter are still triggered to work, and the uncontrolled reverse rectification part is in operation, causing the inverter to work in reverse.