Inverter overvoltage prevention measures - Database & Sql Blog Articles

Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

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Since the causes of overvoltages are different, the countermeasures taken are different. For the overvoltage phenomenon generated during the parking process, if there is no special requirement for the parking time or position, it can be solved by extending the deceleration time of the inverter or free parking. The so-called free stop means that the inverter disconnects the main switching device and allows the motor to coast and stop.

If there is a certain requirement for parking time or parking position, DC braking (DC braking) function can be used. The DC braking function is to decelerate the motor to a certain frequency and then input DC power into the stator winding of the motor to form a static magnetic field. The rotor winding of the motor cuts this magnetic field to generate a braking torque, so that the kinetic energy of the load is converted into electrical energy and is consumed in the form of heat in the rotor circuit of the motor. Therefore, this braking is also called energy braking. In the process of DC braking, two processes of regenerative braking and energy braking are actually included. This braking method is only 30-60% efficient for regenerative braking and has a low braking torque. Since the motor is overheated by consuming energy in the motor, the braking time should not be too long. Moreover, the DC braking start frequency, braking time and braking voltage are all manually set and cannot be automatically adjusted according to the level of the regenerative voltage. Therefore, DC braking cannot be used for overvoltage generated during normal operation, and can only be used for Braking when parking.

For deceleration (from high speed to low speed, but not stopping), the overvoltage generated by the excessive GD2 (flywheel torque) of the load can be solved by appropriately extending the deceleration time. In fact, this method also uses the principle of regenerative braking. The deceleration time is only to control the charging speed of the load to the inverter, so that the 20% regenerative braking capability of the inverter itself can be rationally utilized. As for the load that causes the motor to regenerate due to the action of external force (including the potential discharge), since it is normally in the braking state, the regenerative energy is too high to be consumed by the inverter itself, so it is impossible to use DC braking or The method of extending the deceleration time.

Compared with DC braking, regenerative braking has higher braking torque, and the braking torque can be related to the braking torque required by the load (ie, the level of regenerative energy). Automatic control. Regenerative braking is therefore best suited to provide braking torque to the load during normal operation.