How can industrial servo buffer circuits suppress spikes?

Servo snubber circuits are used to suppress voltage spikes and oscillations generated when IGBTs or diodes are turned off. Yinte Electronics commonly uses an RCD snubber circuit design: an RCD network is connected in parallel between the IGBT's collector and emitter (CE). The capacitor C_snub's value is based on the energy to be absorbed (I*L_parasitic), typically 100pF-2.2nF/1kV, and a C0G or film capacitor is used. The resistor R_snub is used to dampen and limit the capacitor's discharge current, with a value chosen to keep the circuit critically damped, typically 10-100Ω. The diode D_snub is a fast recovery diode (such as FR107) to quickly conduct current. In terms of layout, the snubber circuit loop area must be extremely small, with components placed close to the IGBT pins. Another lossless snubber solution is to use a non-linear capacitor (such as a 14D series varistor) connected in parallel between the CE. A well-designed buffer circuit can suppress voltage spikes from 130% of the DC bus voltage to within 110%, and reduce the corresponding high-frequency (>10MHz) radiated noise by 5-10dB, while improving device reliability.