A dynamic safe state control circuit is disclosed that controls an electrical motor based on vehicle speed. A microcontroller or other processing device is configured to control an inverter system of an electrical motor. The dynamic safe state control circuit is configured to receive a first signal that corresponds to a speed of the electric motor. The circuit is configured to activate any one of a plurality of safe states in the inverter system based on the first signal and in response to a malfunction in the microcontroller.

A method for controlling a brushless and sensorless, direct current electric motor (3) for motor vehicle equipment, wherein the electric motor (3) comprises a rotor and phases (A, B, C) powered by a pulse width modulation applied to a power inverter (1) of the electric motor (3), and wherein, beyond a minimum threshold (S.sub.min) of the rotation speed of the rotor, the position of the rotor is determined from a measurement of electromotive forces at the phases (A, B, C) of the electric motor (3), said control method is characterised in that, in the event of a command (104) to stop the electric motor (3), the speed of rotation of the rotor is reduced (105) from a nominal speed to a predetermined rotation speed (V1) within a range between the minimum threshold (S.sub.min) and 10% above said minimum threshold (S.sub.min) by modifying the pulse width modulation, then the electric motor (3) is stopped (106) in a predetermined position by short-circuiting the branches (A, B, C) of the inverter (1) when the predetermined position is reached.

The invention relates to a system 1 for controlling a voltage converter comprising a plurality of high-side switches forming a high group and a plurality of low-side switches forming a low group, the control system 1 comprising: a module 10 for measuring a voltage V of the DC voltage source B, a module 11 for comparing the measured voltage V with a first safety threshold OV1, a control module 12 for controlling a first group of switches so as to close chosen from the high group or the low group, if the comparison module 11 indicates that the measured voltage V is higher than the first safety threshold OV1.

A power tool is provided including a brushless direct-current (BLDC) electric motor having a stator and a rotor. The power tool includes power switches including high-side switches and low-side switches disposed on a direct-current (DC) bus line between a power supply and the electric motor, and a controller configured to electronically brake the motor by simultaneously closing the high-side switches or the low-side switches to electrically short the stator windings. In an embodiment, the controller is configured to monitor a voltage of the DC bus line, and if the voltage of the DC bus line is lower than a voltage threshold, execute electronic braking by toggling between closing the high-side switches and closing the low-side switches over braking cycles, and if the voltage of the DC bus line is greater than the voltage threshold, execute braking by closing only the high-side switches or the low-side switches over the braking cycles.

A motor drive system includes an input portion arranged to receive a DC input voltage across first and second conductors. An inverter is connected across the first and second conductors, and is arranged such that, in a normal mode, the inverter receives the DC input voltage and generates an AC drive voltage. A motor is connected to the inverter and is arranged such that, in the normal mode of operation, the motor receives the AC drive voltage. A first normally-open switch is connected along the first conductor between the input portion and the inverter. A damping controller comprising a second normally-closed switch and a damping means is connected in series between the first and second conductors. When the operated in the normal mode, the first switch is closed and the second switch is open. In a damping mode, the first switch is open and the second switch is closed.

A safety signal is sent to a relay coupled to a plurality of power leads of a motor wherein a default state of the relay is to short the plurality of power leads together and wherein the safety signal maintains the relay in an open state. The safety signal to the relay is deasserted in response to a determination that an unsafe condition has occurred.

A safety signal is sent to a relay coupled to a plurality of power leads of a motor wherein a default state of the relay is to short the plurality of power leads together and wherein the safety signal maintains the relay in an open state. The safety signal to the relay is deasserted in response to a determination that an unsafe condition has occurred.

A motor controlling circuit is provided. A first terminal of a first high-side transistor and a first terminal of a second high-side transistor are coupled to a common voltage. A first terminal of a first low-side transistor is connected to a second terminal of the first high-side transistor. A first node between the first terminal of the first low-side transistor and the second terminal of the first high-side transistor is connected to a first terminal of a motor. A first terminal of a second low-side transistor is connected to a second terminal of the second high-side transistor. A second node between the first terminal of the second low-side transistor and the second terminal of the second high-side transistor is connected to a second terminal of the motor. The driver circuit regulates at least one of the transistors such that no current flows to the common voltage.

A cart may include: a driving wheel; a motor configured to rotate the driving wheel; a motor drive circuit configured to drive the motor; a motor brake circuit configured to electrically brake the motor; a rotation speed sensor configured to detect a rotation speed of the motor; and a control device configured to control the motor via the motor drive circuit and the motor brake circuit based on a target rotation speed of the motor and the rotation speed detected by the rotation speed sensor. The motor brake circuit may include an electronically variable resistance element configured to operate in a linear mode and a switching mode in response to a control input signal. The motor brake circuit may be configured to operate. the electronically variable resistance element in the linear mode when braking the motor.

A cart may include: a driving wheel; a motor configured to rotate the driving wheel; a motor drive circuit configured to drive the motor; a motor brake circuit configured to electrically brake the motor; a rotation speed sensor configured to detect a rotation speed of the motor; and a control device configured to control the motor via the motor drive circuit and the motor brake circuit based on a target rotation speed of the motor and the rotation speed detected by the rotation speed sensor. The motor brake circuit may include an electronically variable resistance element configured to operate in a linear mode and a switching mode in response to a control input signal. The motor brake circuit may be configured to operate. the electronically variable resistance element in the linear mode when braking the motor.