The process of energy consumption braking is as follows: A. When the motor decelerates and reverses under the action of external force (including being dragged), the motor runs in the power generation state, and the energy is fed back to the DC loop to increase the bus voltage; B. When the DC voltage reaches the state where the brake unit is on, the power tube of the brake unit is turned on, and the current flows through the brake resistor; C, the brake resistor consumes electric energy as heat energy, the motor speed decreases, and the bus voltage also decreases; D, bus bar The voltage drops to the value that the brake unit is to be turned off, the power tube of the brake unit is turned off, the brake resistor has no current flowing; E, the sample bus voltage value, the brake unit repeats the ON/OFF process, balances the bus voltage, and makes the system normal operation. Micro camera is the product of modern high-tech, also known as micro monitor, which has the characteristics of small size, powerful function and good concealment. Bottle Camera,Spy Hidden Camera,Micro camera Jingjiang Gisen Technology Co.,Ltd , https://www.jsgisentec.com
Braking unit and brake resistor matching
A, first estimate the braking torque
= ((motor moment of inertia + motor load measurement to the motor measured moment of inertia) * (pre-brake speed - brake speed)) / 375 * deceleration time - load torque In general, when braking the motor There is a certain loss inside the motor, which is about 18%-22% of the rated torque. Therefore, if the calculated result is less than this range, there is no need to connect the brake device;
B, then calculate the resistance of the braking resistor
= square of the operating voltage value of the braking element / (0.1047 * (brake torque - 20% motor rated torque) * motor speed before braking)
During the operation of the brake unit, the voltage rise and fall of the DC bus depends on the constant RC, R is the resistance of the brake resistor, and C is the capacity of the internal electrolytic capacitor of the inverter. Here, the braking unit operating voltage value is generally 710V.
C. Then select the brake unit. When the brake unit is selected, the maximum current of the brake unit is the only basis for selection. The calculation formula is as follows:
Brake current instantaneous value = brake unit DC bus voltage value / braking resistance value
D. Finally calculate the nominal power of the braking resistor. Because the braking resistor is a short-time working system, according to the characteristics and technical specifications of the resistor, we know that the nominal power of the resistor will be less than the power consumption during power-on. Get: Brake resistor nominal power = Brake resistor derating factor X Average power consumption during braking X Brake usage %
Braking characteristics The advantage of energy braking (resistive braking) is that the construction is simple, the disadvantage is that the operating efficiency is reduced, especially when frequent braking, a large amount of energy will be consumed, and the capacity of the braking resistor will increase.
Micro cameras are widely used, suitable for aviation, commerce, media, enterprises and institutions, families and other industries. The emergence of miniature cameras brings convenience to people's lives, and at the same time, some phenomena related to corporate secrets and personal privacy also arise.