Full-Bridge Motor Drive Sleep Control to Prevent Through-Current
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Solution Overview
Problem
Motor drive circuits face issues with high standby and through-currents during sleep mode due to the configuration of driver circuits operating in negative logic, leading to potential damage from arm short-circuits.
Innovation Solution
A motor drive circuit design that includes field-effect transistors (FETs) and driver circuits with a control circuit that outputs negative logic signals to reduce standby current and uses a semiconductor switch to decouple output stages from ground, preventing through-currents by turning off FETs during sleep mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the controller outputs negative logic signals to all driver circuits during sleep mode to reduce standby current, then standby current is reduced, but all FETs turn on causing arm short-circuit and through-current damage
Solution Approach 1:
The driver circuits are divided into two groups: first driver circuits (for first FETs) that receive negative logic signals during sleep mode, and second driver circuits (for second FETs) that are actively controlled to output high voltages. This segmentation allows selective control of FET states to prevent arm short-circuit while reducing standby current.
Solution Approach 2:
A switch circuit is introduced as an intermediary component between the controller and the second driver circuits. This switch actively manages the output stage to ensure high voltages are maintained on the second FETs during sleep mode, preventing unintended conduction and arm short-circuit conditions.
2Device complexity
If driver circuits operate in negative logic to simplify control, then control complexity is reduced, but through-current flows during sleep mode causing circuit damage
Solution Approach 1:
The switch circuit is configured to proactively maintain high voltage outputs on the second driver circuits before the sleep mode begins. This preliminary action ensures that the second FETs are already in the off-state when negative logic signals are applied to the first driver circuits, preventing through-current flow.
Solution Approach 2:
The switch circuit acts as a protective intermediary that decouples the second driver circuits from ground during sleep mode. This intermediary function allows negative logic operation to continue while blocking the harmful through-current path that would otherwise cause circuit damage.
Data Source
AI summary
One aspect of the present disclosure provides a motor drive circuit including: first through fourth FETs forming a full-bridge circuit; first through fourth driver circuits; a control circuit; and a switch. The switch operates at least one of the first through fourth driver circuits such that at least one of the first through fourth driver circuits outputs at least one of first through fourth high voltages to at least one of gates of the first through fourth FETs, during the sleep mode of the control circuit.