At present, the mainstream servo drives all use digital signal processor (DSP) as the control core, which can realize relatively complex control algorithms and realize digitization, networking and intelligence. Power devices generally adopt the drive circuit designed with the intelligent power module (IPM) as the core. Start the circuit to reduce the impact on the driver during the start-up process. The power drive unit first rectifies the input three-phase power or mains power through a three-phase full-bridge rectifier circuit to obtain corresponding DC power. After the rectified three-phase electricity or mains electricity, the three-phase permanent magnet synchronous AC servo motor is driven by the frequency conversion of the three-phase sinusoidal PWM voltage type inverter. The whole process of the power drive unit can be simply said to be the process of AC-DC-AC. The main topological circuit of the rectifier unit (AC-DC) is a three-phase full-bridge uncontrolled rectifier circuit.

The servo driver is used to drive the servo motor to make the equipment generate power and operate normally. There are many kinds of functional subdivisions, and the functions vary with different brands. There are relatively many functions of servo motors similar to Kefeng Automation, and the inventory generally has the following aspects:
1. Parameters are grouped and set, and the control mode can be switched arbitrarily;
2. Control power AC input, wide voltage input that can be set;
3. Instantaneous power failure and fast shutdown protection function;
4. Regenerative braking and dynamic braking functions;
5. Absolute value system voltage monitoring, low voltage warning function;
6. The debugging software supports parameter management, monitoring and oscilloscope functions.