A small digital DC servo motor drive circuit is characterized by its simplicity, strong anti-interference capability, high output efficiency, and small size, facilitating low-cost integrated design. The circuit includes a logic protection circuit, an H-bridge drive isolation circuit, an H-bridge circuit, an isolation power supply, a non-isolated upper half-bridge drive power supply, a non-isolated lower half-bridge drive power supply, and an external power supply. The logic protection circuit filters out erroneous signals in the control signals that could cause abnormal output of the H-bridge circuit. The H-bridge drive isolation circuit completely isolates the low-voltage digital portion from the high-power digital portion. The non-isolated upper half-bridge drive power supply and the non-isolated lower half-bridge drive power supply respectively convert and output two power supply voltages that are not isolated from the external power supply to the H-bridge drive isolation circuit, which then drives the H-bridge circuit. The H-bridge circuit drives the DC servo motor.
Based on motor inertia, they can be divided into:
1. Low inertia DC motors – Automatic drilling machines for printed circuit boards
2. Medium inertia DC motors (wide speed range DC motors) – Feed systems of CNC machine tools
3. High inertia DC motors – Spindle motors of CNC machine tools
4. Special types of low inertia DC motors
Basic characteristics:
1. Mechanical characteristics: The law by which the motor speed n changes with the electromagnetic torque M when the input armature voltage Ua remains constant is called the mechanical characteristic of a DC motor.
2. Regulation characteristics: The law by which the steady-state speed n of a DC motor changes with the armature control voltage Ua under a certain electromagnetic torque M (or load torque) is called the regulation characteristics of a DC motor.
3. Dynamic characteristics: There is a transition process from the original steady state to a new steady state; this is the dynamic characteristic of a DC motor.