HP INCFollow

Abstract

DC‐DC converters are needed to efficiently convert between different voltage levels within the electrical

architecture of LFP (Large Format Printing) products. Traditionally, analog solutions have been presented to

implement the controller of the converter, but this solution presents several limitations in terms of flexibility,

modularity, etc.

To overcome these limitations, digital solutions, for instance based in a MCU (microcontroller) are being

proposed, since new applications in the field of power electronics can be targeted with MCUs at a very

competitive cost, due to the advances of these devices not only in terms of computational and memory

features, but also in terms of embedded peripherals such as comparators, DACs, operational amplifiers, etc.

When a DC‐DC Boost Converter is controlled with a PCMC (Peak Current Mode Control) scheme, subharmonic

oscillations can occur. To overcome this issue, slope‐compensation must be implemented, which consists of

adding an additional slope to the sensed inductor current signal. When the inductor current is sensed on the

HS (High‐Side), it is preferred to implement the slope compensation by subtracting this additional slope to the

control signal. In more advanced MCUs, sawtooth generators are usually embedded in the DAC channels

employed for the control signal generation, so that slope‐compensation can be easily implemented. However,

these MCUs are usually out of scope when low‐cost is targeted.

In consequence, this works presents a simple electronic solution to implement slope‐compensation by

subtracting a sawtooth signal from the control signal, mainly based in a capacitor and a discharge current

source. Three possible implementations are presented for the current source, trading‐off complexity, and

performance.

Creative Commons License

Creative Commons License
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