| 摘要 |
PURPOSE: A circuit for generating the dead time signal is provided to protect the power switching devices of a servo driver or an inverter from surge. CONSTITUTION: A servo driver comprises a PWM generating circuit, a dead time generating circuit(20), and a gate driving circuit. When the power switching devices connected in series are turned on simultaneously then the over-current destroys them. A dead time generating circuit(20) has dip switches(24) setting the initial value and a binary counter(23) counting the delay time. The counter produces a carry out signal based on the reference clock. The carry out signal from a NOT gate is reversed and becomes a delay time. A D-flip-flop(22) receives a delay time through clock path and generates the delayed PWM signal. An AND gate generates a gate control signal UPPER_A to drive the power switching device and a NOR gate generates a gate control signal LOWER_A to drive the power electronic device, so the circuit prevents the devices to be shorted.
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