A controller is adapted to be coupled to a brushless direct current (DC) motor and includes an analog-to-digital converter (ADC), a computing device, and a driver. The ADC is configured to receive an analog back electromotive force (BEMF) waveform from the brushless DC motor and sample the analog BEMF waveform to produce a digital BEMF waveform. The computing device is coupled to the ADC and is configured to receive the digital BEMF waveform and determine a position and a speed of the rotor based on the digital BEMF waveform. The driver is coupled to the ADC and the computing device and is configured to receive the position and the speed of the rotor and provide a drive signal based on the position and the speed of the rotor of the brushless DC motor.

An input end of a first power conversion circuit of the system is connected to a power supply, and an output end of the first power conversion circuit is connected to a stator winding of an electrical excitation motor. An input end of a second power conversion circuit is connected to the power supply, and an output end of the second power conversion circuit is connected to a primary side of an excitation transformer. The excitation transformer transmits energy required by an excitation winding of the electrical excitation motor from a stator to a rotor. A first controller controls the first power conversion circuit to inject a current excitation into the stator winding, so that a current is generated on the excitation winding. A detection circuit obtains a response signal of the primary side of the excitation transformer and sends the response signal to a second controller.

An input end of a first power conversion circuit of the system is connected to a power supply, and an output end of the first power conversion circuit is connected to a stator winding of an electrical excitation motor. An input end of a second power conversion circuit is connected to the power supply, and an output end of the second power conversion circuit is connected to a primary side of an excitation transformer. The excitation transformer transmits energy required by an excitation winding of the electrical excitation motor from a stator to a rotor. A first controller controls the first power conversion circuit to inject a current excitation into the stator winding, so that a current is generated on the excitation winding. A detection circuit obtains a response signal of the primary side of the excitation transformer and sends the response signal to a second controller.

Saliency tracking for brushless direct current (BLDC) motors and other permanent magnet synchronous motors (PMSMs) is provided. Embodiments generate an accurate estimate of rotor position for use in field-oriented control (FOC) of BLDC motors. In addition, a robust saliency tracking algorithm provides for the use of BLDC motors in low-speed high-torque applications without the need of external sensors. This enables sensorless application of higher level algorithms as well, such as servo control. In addition, accurate measurement of motor phase inductance and flux linkage can be provided without any additional equipment.

Saliency tracking for brushless direct current (BLDC) motors and other permanent magnet synchronous motors (PMSMs) is provided. Embodiments generate an accurate estimate of rotor position for use in field-oriented control (FOC) of BLDC motors. In addition, a robust saliency tracking algorithm provides for the use of BLDC motors in low-speed high-torque applications without the need of external sensors. This enables sensorless application of higher level algorithms as well, such as servo control. In addition, accurate measurement of motor phase inductance and flux linkage can be provided without any additional equipment.

A single-phase brushless DC motor includes a rotor rotatable about a central axis, a stator including salient pole portions, a stator core including a slot between the salient pole portions, and a winding wound around the salient pole portions, the stator opposing the rotor with an air gap interposed therebetween, and a substrate fixed to the stator and including a driver to perform energization control of the winding. The driver includes a Hall element to acquire a timing of the energization control. The substrate includes a Hall IC to detect a circumferential position of the rotor separately from the driver.

The present invention includes a phase angle detection unit generating a phase angle signal switched at a timing at which a cogging torque generated with the rotation of a rotor of a brushless DC motor reaches near a peak on a negative side hindering the rotation of the rotor, an inverter circuit energizing coils of respective phases of the brushless DC motor by switching elements according to an input of a driving signal, an energization period calculation unit calculating an energization period Tw from a target rotation speed set for the brushless DC motor, and a drive control unit energizing the coils sequentially by outputting the driving signal to the respective switching elements for each energization period, gradually increasing a duty of the driving signals to the switching elements at a start of each energization period, and decreasing the duty after the phase angle signal is switched.

The present invention includes a phase angle detection unit generating a phase angle signal switched at a timing at which a cogging torque generated with the rotation of a rotor of a brushless DC motor reaches near a peak on a negative side hindering the rotation of the rotor, an inverter circuit energizing coils of respective phases of the brushless DC motor by switching elements according to an input of a driving signal, an energization period calculation unit calculating an energization period Tw from a target rotation speed set for the brushless DC motor, and a drive control unit energizing the coils sequentially by outputting the driving signal to the respective switching elements for each energization period, gradually increasing a duty of the driving signals to the switching elements at a start of each energization period, and decreasing the duty after the phase angle signal is switched.

An input voltage control method includes: a power supply, a first rectifier circuit and a second rectifier circuit connected between the positive terminal and the negative terminal of the power supply. The first rectifier circuit and the second rectifier circuit are connected in parallel with each other, an output end of the first rectifier circuit is connected to the motor via a driver circuit. An output end of the second rectifier circuit is connected to a controller through a voltage detection circuit. The controller collects a bus current value and collects a bus voltage value. The controller stores a target duty cycle value and a target voltage value. The controller determines a corresponding target voltage value based on the collected bus current value and obtains an output control duty cycle to drive the motor.

A current control method and a motor control circuit are provided. The motor control circuit includes a first rectification circuit and a second rectification circuit connected in parallel between a live wire and a natural wire of a power supply, a sampling resistor, and a controller connected to the second rectification circuit. The first rectification circuit is connected to the motor. The current control method include obtaining a periodic waveform signal of a bus voltage; collecting a bus current value through the sampling resistor; sampling the periodic waveform signal for a plurality of times; linearly fitting multiple voltage values obtained at a plurality of sampling time points to obtain multiple slopes; obtaining a power frequency according to the multiple slopes; calculating a compensation current value according to the power frequency; and generating a control signal according to the compensation current value and the bus current value.