Publication Date: 2014-Apr-04
The IP.com Prior Art Database
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Title: Integrated Brake
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This idea is in the field of variable speed drives and relates, in particular, to variable speed drives having active front end (AFE) functionality (AFE drives). mode. In the normal mode, a load (typically a motor) is driven by an IGBT module that draws power from a DC link. In the braking mode, power is provided (typically from a motor/generator)
Some known AFE drives have a dedicated brake chopper for braking operation which leads to
additional part count, cost and potentially reduced reliability. This idea seeks to provide brake
chopper functionality in an alternative manner.
There are two modes of operation of an existing AFE drive: a "normal" mode and a "braking"
and tends to result in the DC link voltage rising. As is known in the art, the braking mode may
use a chopper circuit to dissipate energy to prevent the DC link voltage from rising too high.
The circuit schematic below shows an exemplary implementation of the present idea. The
circuit schematic above shows an active front end (AFE) system including an AC supply, an
LCL filter and an active infeed converter (AIC). The AIC is a controllable rectifier and is used to
generate the required DC link voltage. The specific configuration of the circuit below is an
example - many variants are possible.
In the normal mode of operation of the circuit above, the contactor CON1 is closed and the
contactor CON2 is open, such that the resistors R1, R2 and R3 are disconnected. Thus, the
AFE stage works as in existing AFE systems with the AIC circuit (consisting of IGBTs 1 to 6)
providing a DC lin...