GENERAL INTRODUCTION ENERGY REGENERATION AND DYNAMIC BASE IN INVERTER
I. Dynamic braking
It is the state of the engine working as a generator (in loads that need to be continuously decelerated such as elevators, cranes, …) that the mechanical energy of the motor accumulated during the previous working process changes. into electrical energy dissipated as heat during braking.
Resistance braking: when the AC power of the motor is disconnected, the IGBT latch will automatically open on the DC Bus. The IGBT is connected to a suitable braking resistor (power resistor). The energy from the motor is returned to the DC Bus through the brake resistor and therefore will not affect the inverter.
Standard inverter
1 Rectifier.
2 DC bus
3 Inversion
4 Dynamic brake module.
Dynamic braking module (must be installed for non-integrated inverters):
| 1 AC Power Supply | 7 DC brake fuse |
| 2 fuse | 8 Harmonic attenuator (option) |
| 3 Rectifier | 9 Dynamic brake module |
| 4 DC bus | 10 Braking resistor |
| 5 Inverter DC fuse | 11 Engines |
| 6 Inverters |
The dynamic braking module works: Conducts excess energy from the DC bus to the brake resistor when needed. The brake module operates when the DC voltage exceeds a certain maximum limit. The voltage increase is usually caused by the deceleration of the motor. Users can set brake function, brake kinetic energy when needed.
II. Regenerative brake
In AC motors, there will be operating modes that will produce energy back to the source like a generator. That energy source is called renewable energy. In most cases will be discarded or released back to the source. That causes waste and pollution of electricity. Especially in equipment such as cranes, cranes, winding machines… often operating under regenerative braking mode, the problem is even bigger.
To solve that problem, Yaskawa has introduced the compact and complete D1000 series of energy regenerative inverters, used in cyclic regenerative loads or intermittent braking applications. With that function, the braking energy of the motor is returned to the inverter and distributed to the supply network so that it can be used by other equipment. Compared with the mechanical or resistive braking method, which wastes braking energy as heat, the regenerative inverter will significantly save energy consumption and cooling.
The regenerative inverter operates in 3 modes:
- Full regenerative mode: When regenerative capacity is needed, regenerative rectification uses IGBT control pulses (above 120 degrees). This allows maximum power flow to the supply network. In this mode, the regenerative rectifier also filters out most of the voltage ladder by cross driving the IGBTs for a certain period of time.
- Regulating mode: When the motor needs to run, current flows through the diodes as in diode mode. When regenerative capacity is required, the flow to the supply network is regulated using shorter IGBT control pulses than in full regenerative mode. Throttling mode also makes the DC voltage higher during load changes.
- Diode mode: Regenerative rectifier operates in diode mode when the power is switched from mains to DC bus. The IGBTs are off and all current flows through the diodes to the DC bus. Users can also force diode mode to use with parameter 120.29. If diode mode is forced to use, the regenerative rectifier cannot supply the power returned to the grid.
Advantages of the regenerative brake inverter line:
With the technical characteristics analyzed above, we can clearly see the outstanding advantages of the regenerative inverter line compared to the standard inverter line using the kinetic braking method:
- Saving power consumption because the amount of electricity returned to the grid is not consumed in the discharge resistor
- Energy saving by not cooling the brake unit
- All integrated in 1 should cut costs, installation time
- Quick and easy inverter installation
- No additional discharge resistors (even brake modules) are required to save installation space
- No additional cooling is required to handle the heat generated by the resistor
- Simple wiring
- Few spare parts needed
- Stable output voltage under all load conditions, even with fluctuating supply voltage
1294
09/06/2021
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