Elevator inverter control power board ThyssenKrupp RMB2 RMB3 Elevator parts

Thyssen Brake Lift Board Power Board RMB3/RMB2. The RMB3 board is an upgraded version of the RMB2 board. Apart from the model upgrade, the rest are basically the same, so you can use it with confidence.

With the development of science and technology and the continuous improvement of industrial automation, frequency converters have been widely used. The inverter is a power control device that uses frequency conversion technology and microelectronics technology to control the AC motor by changing the working power frequency of the motor.

The inverter drive circuit is mainly composed of a rectifier circuit, a buffer circuit, a filter circuit, a brake circuit, a lightning protection circuit, and an inverter circuit.

Working principle of buffer circuit

At the moment when the inverter is powered on, the charging current on the filter capacitors C1 and C2 is relatively large. Excessive impact current may cause damage to the three-phase rectifier bridge; at the same time, the input power supply voltage drops and distorts instantly. In order to reduce the impact current, the buffer resistor R1 is connected in series in the circuit at the moment when the inverter is just turned on to form an RC circuit so that the impact current on the capacitors C1 and C2 can be buffered. When the charging voltage of the filter capacitors C1 and C2 reaches a certain level (80%), J1 is turned on and R1 is short-circuited.

Working principle of filter circuit

The voltage and current output by the three-phase rectifier bridge belong to DC pulse voltage and current. In order to reduce the fluctuation of DC voltage and current, the large-capacity aluminum electrolytic capacitor of the DC filter circuit is usually composed of several capacitors connected in series and in parallel to form a capacitor group to obtain the required withstand voltage and capacity. In addition, because the capacity of electrolytic capacitors has a large discreteness, this will make them unequal with the voltage. Therefore, each capacitor should be connected in parallel with a voltage-uniforming resistor with equal resistance to eliminate the influence of discreteness.

Working principle of braking circuit

When the motor is used in the regenerative braking area (slip is negative), the regenerative energy is stored in the capacitor of the smoothing circuit, which increases the DC voltage. Generally speaking, the energy accumulated by the inertia of the mechanical system (including the motor) is greater than the energy stored in the capacitor. When rapid braking is required, the reversible converter can be used to feed back to the power supply or set a braking circuit (switch and resistor) to consume the regenerative power to prevent the DC bus voltage from rising.

Working principle of lightning protection circuit

The lightning protection circuit consists of a varistor and a gas discharge tube, which are connected in series in the R phase input circuit. When a large voltage is connected in series to the input circuit, the voltage will be released through the lightning protection circuit through the ground to reduce damage to the inverter.

Working principle of inverter circuit

The function of the inverter circuit is to convert the DC power output of the DC circuit into an AC power supply with adjustable frequency and voltage under the action of the control circuit. The output of the inverter circuit is the output of the inverter, so the inverter circuit is one of the core circuits of the inverter and plays a very important role.

The most common inverter circuit structure is a three-phase bridge inverter circuit composed of six power switching devices (GTR, IGBT, GTO, etc.). By regularly controlling the on and off of the power switching devices in the inverter, a three-phase AC output of any frequency can be obtained.

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