Working principle of inverter brake resistor_Performance characteristics of inverter brake resistor

The inverter braking resistor is a carrier used to consume the regenerative energy of the motor in the form of heat energy. It includes two important parameters: resistance value and power capacity.

When the motor or other inductive load driven by the inverter stops, it is generally realized by energy consumption braking, that is, the kinetic energy of the motor after stopping and the magnetic energy in the coil are consumed through another energy-consuming element, so as to achieve rapid stopping. When the power supply stops, the inverter circuit of the inverter conducts in the reverse direction, and feeds back the remaining electric energy to the DC bus of the inverter. The voltage on the DC bus will increase as a result. When it increases to a certain value, the braking resistor of the inverter will be put into operation, so that this part of the electric energy is consumed by the heating of the resistor, while maintaining the voltage on the DC bus at a normal value.

Working principle of inverter brake resistor

When the inverter drives the motor in a braking state (generating state), such as when a crane is lowering a heavy object, or a load with a large inertia stops quickly, the kinetic energy (potential energy) will be converted back into electrical energy and returned to the inverter DC bus, causing the bus voltage to be very high. If your inverter has a braking unit, it will detect that the bus voltage is higher than a certain threshold, and it will turn on the switch between the braking resistor and the bus, and the energy will be consumed by the braking resistor, and the braking resistor will heat up.

Normally, the braking resistor will never heat up. If it heats up during normal operation, it means that the braking unit is broken, or there is a hardware problem that causes the braking resistor to always be connected to the DC bus. In this case, there will be no major problem with the operation of your inverter, but the energy consumption will definitely be high.

When the inverter output controls the motor in acceleration or constant speed state, the braking resistor does not work. However, when the motor is decelerating or emergency stopping, the voltage of the DC circuit in the inverter will increase because the motor is in regenerative braking state. The braking resistor consumes this increased energy in the form of heat.

The asynchronous motor will be in a regenerative power generation state, generating feedback current. This current returns to the DC circuit through the return diode (D1-D6) and charges the main capacitor, increasing the DC voltage. In order to avoid excessive voltage and damage to the inverter, a braking resistor R is connected to the DC circuit side. When the DC voltage exceeds a certain value, the transistor switch TR is turned on and connected to the braking resistor, and the feedback energy is consumed in the form of heat energy on the resistor R.

Performance characteristics of inverter brake resistor

A) BCGT resistors adopt the design process and manufacturing standards of the parent company, GINO of Germany. The resistor material is made of special alloy steel with a patent. The temperature coefficient of this material is very small, so that the resistance value of the resistor changes very little during operation;

B) HCGT-B resistors use the design technology of its parent company, Italy TELEMA. The resistor element material is stainless steel, with a unique design structure. It uses bolts to connect and fix the resistor sheet, which is the best solution. Compared with traditional welding, it has the characteristics of simple connection, beautiful appearance, and easy maintenance. The biggest advantage is its large capacity, which is 3 times the capacity of ordinary resistor sheets, which is conducive to reducing the number of resistor sheets, improving cost performance, and enhancing customer competitiveness;

According to the use requirements of the motor, we can match brake resistors of different powers and resistance values ​​for various types of inverters, and we can also make special designs for heat dissipation conditions and installation methods according to the customer's use functions and environment.

We provide brake resistors of various models and sizes to match ABB inverter, SIEMENS inverter, AB inverter, Yaskawa inverter and other domestic inverters.