Pitch motor drive circuit which can operate in emergency mode

Pitch drive circuit which can operate in emergency mode for a wind or water turbine system, comprising:

• at least one rectifier unit,
• at least one DC intermediate circuit,
• a first inverter unit and a pitch three-phase motor with motor trains that can be contacted on both sides, where a first contact side of the motor trains is connected to the first inverter unit, a second contact side of the motor trains is connected to a second inverter unit and at least one switching element is connected to at least one contact side of the motor trains, so that during normal operation of a first switching state of the switching element the motor trains can be supplied with current by both inverter units, and in an emergency operation of a second switching state of the switching element the motor trains can be supplied with current by a single inverter unit,
• wherein each converter unit is switchably connected via one decoupling switching element to the supply network, and each inverter unit is switchably connected via at least one decoupling switching element to the motor trains of a contact side, and both inverter units are connected to a braking chopper unit.