Power inverters are becoming more and more popular in the market. As the popularity of automobiles is increasing, you can use inverter power to connect to the car battery to drive electrical appliances and power tools when you go out to work or travel without mains power. Therefore, the power inverter as a DC to AC power converter used when the car is moving, and to bring a lot of convenience to our life, which is the necessary supplies for people with car.
Inverter power supply, also called inverter, is a device that can change its frequency, which can achieve DC input, and then output AC. The working principle is the same as switching power supply, but the oscillation frequency is within a certain range, for example, if this frequency is 50HZ, the output is AC 50HZ.
Inverter braking resistor, generally divided into two types, one is a painted high-power electric winding resistor, and the other is an aluminum housing resistor with its own heat sink, mainly used in the mechanical system of power inverter control motor to stop quickly, to help the motor to convert its regenerative electrical energy generated by the rapid stop into heat energy.
The following is the action process of the braking unit：
a. When the motor is decelerated under the action of external force, the motor runs in the power generation state and generates regenerative energy. Its generated three-phase AC electric potential is rectified by the three-phase fully controlled bridge composed of six renewal diodes in the inverter part of the inverter power supply, so that the DC bus voltage in the inverter power supply continues to rise.
b. When the DC voltage reaches a certain voltage (brake unit opening voltage), the brake unit power switch tube opens, the current flows through the inverter braking resistor.
c. The inverter braking resistor releases heat and absorbs regenerative energy, the motor speed drops, and the DC bus voltage of the inverter power supply decreases.
d. When the DC bus voltage drops to a certain voltage (brake unit stop voltage), the brake unit power tube shuts off. At this time there is no braking current flowing through the resistor, the inverter braking resistor in the natural heat dissipation, reduce their own temperature.
e. When the DC bus voltage rises again to make the brake unit action, the brake unit will repeat the above process to balance the bus voltage, so that the system operates normally.
The motor in the process of fast stop, due to the inertia, will produce a large amount of regenerative energy. If not consume this part of the regenerative energy in time, it will act directly on the inverter braking resistor. Then there will be a fast braking process of the motor regenerative energy change into heat directly. So, that regenerative energy will not feedback to the inverter power supply, and will not cause voltage fluctuations in the grid, thus ensuring the smooth operation of the inverter power supply.