When a failure of current detection parts occurs while a synchronous machine is operating, the failure of the current detection parts is detected and the operation of the synchronous machine is continued. An open-loop control part for performing control without using the detected current values of the current detection parts and a closed-loop control part for performing control using the detected current values are included, and a failure of the current detection parts is detected while the open-loop control part is operating.

A communication system for use in a switching module includes a low-side control block coupled to control switching of a low-side switch of the switching module. The low-side control block is further coupled to be referenced with a low-side reference system ground. A high-side control block is coupled to control switching of a high-side switch of the switching module. The high-side control block is further coupled to be referenced with a floating node of the switching module. During steady state operation, the low-side control block is coupled to send signals during each switching cycle to the high-side control block to turn the high-side switch on and off. A status update is communicated from the high-side control block to the low-side control block through a first single-wire communication link.

A controller is provided to drive an inverter circuit for a PMSM. The inverter circuit is connected to a battery through a DC link capacitor, and is driven in one safe state during a fault condition. The controller monitors at least one parameter with respective threshold value to drive the inverter circuit in one safe state comprising an active Short Circuit (SC) and a Freewheel (FW). While in FW state, the controller switches from the FW state to the SC state if the at least one parameter is above the respective threshold. While in SC state, the controller controls engine speed to bring the PMSM to a predetermined speed when the stator temperature is more than a threshold temperature value. The controller switches from the SC state to the FW state.

This motor drive device comprises: a motor drive circuit that drives a synchronous motor by supplying AC power to the synchronous motor via power lines; an overvoltage protection circuit that short-circuits between the phases of the power lines by turning on a semiconductor switch when driving of the synchronous motor by the motor drive circuit is stopped and prevents the occurrence of overvoltage due to a back electromotive force between the terminals of the synchronous motor; and a temperature estimation unit that calculates a temperature estimation value of the semiconductor switch by using a motor constant and a semiconductor switch constant, said motor constant including at least one of the inertia and back electromotive force constants of the synchronous motor, said semiconductor switch constant including the on-resistance, thermal resistance, and thermal time constant of the semiconductor switch.

A direct-axis current protection method and device for a permanent magnet synchronous motor drive system. The method includes: pre-calculating the direct-axis current of the next moment according to the current voltage transmitted from an inverter to a permanent magnet synchronous motor (PMSM); comparing the direct-axis current of the next moment with a maximum protection current; if the direct-axis current of the next moment is less than the maximum protection current, continuing transmitting the current voltage to the PMSM; if the direct axis current of the next moment is greater than or equal to the maximum protection current, redistributing the voltage according to a protection direct-axis current and a protection quadrature-axis current, and transmitting the redistributed voltage to the PMSM. The direct-axis current of the next moment is tended to be normal by adjusting the voltage.

A communication system for use in a switching module includes a low-side control block coupled to control switching of a low-side switch of the switching module. The low-side control block is further coupled to be referenced with a low-side reference system ground. A high-side control block is coupled to control switching of a high-side switch of the switching module. The high-side control block is further coupled to be referenced with a floating node of the switching module. During steady state operation, the low-side control block is coupled to send signals during each switching cycle to the high-side control block to turn the high-side switch on and off. A status update is communicated from the high-side control block to the low-side control block through a first single-wire communication link.

Systems and methods are disclosed herein for monitoring and detecting a loss of synchronism in an electric motor, such as a synchronous motor. A monitoring system may compare a measured or provided electric power system frequency with a measured rotational frequency of the rotor of the electric motor. The rotational frequency of the rotor may be obtained from a shaft-mounted device. The monitoring system may determine a slip condition and/or a loss of synchronism of the electric motor.

Monitoring thermal conditions of an electric motor using current signals from power supplied to the motor is disclosed herein. The current signals may be used to calculate composite current values which may be used to calculate slip. The slip may be used to provide thermal monitoring and protection to the electric motor. Slip may be calculated using only values from the stator of the electric motor for providing thermal monitoring and protection to electric motors where rotor measurements are not available.

Monitoring conditions of an electric motor using stator current and voltage signals from power supplied to the motor is disclosed herein. The stator voltage and current signals may be used to calculate instantaneous power values which may be used to calculate slip. The slip may be used to monitor for a locked rotor condition during startup of the motor. The slip value may be used to provide thermal protection to the electric motor.

The mechanism enables torque protection in a brushless motor without the need to use measurement of the current drawn, establishing the torque level based on measurement of the brushless motor rotation speed. The rotation speed corresponding to the nominal torque has therefore been previously established so that when there is over-torque, the rotation speed is decreased. This makes it possible to infer that there is over-torque, thus achieving torque protection for brushless motors which is effective, simple and highly economical. The mechanism has the following: A power supply (1), a rotation direction setter (2), a control unit (3) which is connected to the rotation direction setter (2); a brushless motor (5) which has a connection for sending a BREAK instruction from the control unit (3) to the motor (5), a signal which is sent when a shutdown occurs due to over-torque.