A sensor-less detection circuit includes a first voltage adjustment circuit providing a first output voltage at a first node using one of three input voltages. A second voltage adjustment circuit provides a second output voltage at a second node using all three, or only two, of the three input voltages. The second voltage adjustment circuit acts as an internal virtual neutral point for detecting a zero crossing event of the motor. A differential amplifier is coupled with the first and second nodes and outputs a third output voltage at a third node. A reference buffer has a reference voltage input and provides a fourth output voltage at a fourth node. A comparator is coupled with the third and fourth nodes and outputs a fifth output voltage at a fifth node, the fifth voltage indicating a zero cross event.

An electric motor drive control device includes: an inverter circuit that converts DC power inputted via a DC bus to multiphase AC power and outputs the multiphase AC power to an electric motor; a current detector that detects a DC current flowing in the DC bus; a PWM generator that generates PWM signals and outputs the PWM signals to the inverter circuit; a current calculator that calculates a current value for each of phases to be flowed to the electric motor based upon a value of the DC current and the PWM signals; and a current controller that generates a command signal based upon the current value, and outputs the command signal to the PWM generator, wherein: if one of the phases of the AC power has become missing, the current calculator determines which phase is one that has become missing and calculates current values for other phases.

In accordance with an embodiment, a sensor-less detection circuit is provided that includes a first voltage adjustment circuit coupled for receiving an induced voltage and a second voltage adjustment circuit coupled for receiving a common voltage. A differential amplifier has an inverting input terminal coupled to the first voltage adjustment circuit and a noninverting input terminal coupled to the second voltage adjustment circuit. In accordance with another embodiment, a method for detecting a motor rotor position is provided that includes receiving a first back electromotive force that is at a first voltage level and shifting the first back electromotive force from the first voltage level to a second voltage level. The first back electromotive force is filtered to generate a first filtered voltage; and a first motor rotor position signal is generated in response to comparing the first filtered voltage with a reference voltage.

Provides are a control device for a three-phase synchronous motor in which a position detection accuracy of a rotor can be improved when one three-phase synchronous motor is driven by a plurality of inverters, and an electric power steering device using the same. A control device for a three-phase synchronous motor includes: a three-phase synchronous motor including a first three-phase winding and a second three-phase winding; a first inverter connected to the first three-phase winding; a second inverter connected to the second three-phase winding; a first control device that controls the first inverter on the basis of a rotor position of the three-phase synchronous motor; and a second control device that controls the second inverter on the basis of the rotor position of the three-phase synchronous motor. The first control device estimates the rotor position on a basis of a neutral point potential of the first three-phase winding and a neutral point potential of the second three-phase winding.

A sensor-less detection circuit includes a first voltage adjustment circuit providing a first output voltage at a first node using one of three input voltages. A second voltage adjustment circuit provides a second output voltage at a second node using all three, or only two, of the three input voltages. The second voltage adjustment circuit acts as an internal virtual neutral point for detecting a zero crossing event of the motor. A differential amplifier is coupled with the first and second nodes and outputs a third output voltage at a third node. A reference buffer has a reference voltage input and provides a fourth output voltage at a fourth node. A comparator is coupled with the third and fourth nodes and outputs a fifth output voltage at a fifth node, the fifth voltage indicating a zero cross event.

A control device (1) is configured to reduce the commutation angle error ε of a three-phase (u, v, w) EC motor (2.2) connected via a y-configuration. The three phases (u, v, w) are commutated via a motor control (3) including a rotor position sensor (4) and a control circuit (10). The rotor position sensor (4) senses the relative angular position of the rotor using the neutral-point potential at the neutral point of the y-configuration. The control circuit (10) is configured to impose a desired field weakening current component on the motor control (3) for reducing the commutation angle error ε.

A sensor-less detection circuit includes a first voltage adjustment circuit providing a first output voltage at a first node using one of three input voltages. A second voltage adjustment circuit provides a second output voltage at a second node using all three, or only two, of the three input voltages. The second voltage adjustment circuit acts as an internal virtual neutral point for detecting a zero crossing event of the motor. A differential amplifier is coupled with the first and second nodes and outputs a third output voltage at a third node. A reference buffer has a reference voltage input and provides a fourth output voltage at a fourth node. A comparator is coupled with the third and fourth nodes and outputs a fifth output voltage at a fifth node, the fifth voltage indicating a zero cross event.

Disclosed are a motor control device that can accurately estimate a rotor position based on a neutral point potential even when a load increases, and a brake control device that is driven by the motor control device. The motor control device 3 includes a three-phase synchronous motor 4 including a three-phase winding, an inverter 31 connected to the three-phase winding, a control unit 6 for controlling the inverter based on a rotor position of the three-phase synchronous motor, and a rotational position estimation unit 2 for estimating a rotor position θd based on a neutral point potential Vn of the three-phase winding. The rotational position estimation unit estimates a rotor position selectively using one or more of a plurality of detected values of the neutral point potential according to a pre-estimated value of the rotor position and a voltage application state to the three-phase winding.

A gate drive semiconductor device includes: external terminals to which PWM control signals are supplied; external terminals outputting a drive signal for driving a three-phase BLDC motor; external terminals to which the counter electromotive voltage generated by driving the three-phase BLDC motor is supplied; a zero-cross determination unit generating an interrupt signal indicating timing at which the counter electromotive voltage intersects with a midpoint potential of the three-phase BLDC motor based on the PWM control signal and the counter electromotive voltage; and an external terminal outputting the interrupt signal.

An applied voltage decision unit 510 performs in parallel, a process of determining three-phase AC commands V1u* to V1w* of a voltage applied to a motor by an inverter based on a position, of a rotor of a motor, detected by a position sensor with an output A, and a process of determining three-phase AC commands V2u* to V2w* of the voltage applied to the motor by the inverter based on a neutral point voltage VN of the motor. A PWM modulator 507 alternately outputs a PWM signal according to the three-phase AC commands V1u* to V1w* and a PWM signal according to the three-phase AC commands V2u* to V2w* to the inverter. A control device determines whether or not the position sensor with the output A has failed by comparing the position, of the rotor, detected by the position sensor with the output A with a position, of the rotor, estimated from a neutral point voltage VN of the motor.