Delta Electronics, Inc.

Zhigan Wu

Jianping Ying

Wen-Shi Huang

Jin Wang

Shih-Ming Huang

Wanbing Jin

Weizi Wang

Genfu Zhou

Lijian Wu

Qiong Yuan

The method and circuit for controlling a sensorless single-phase BLDCM having a stator with a winding are proposed. The provided controlling circuit includes a power supply circuit, an inverter coupled to the winding and the power supply circuit, a BEMF detecting circuit coupled to the winding and the inverter and measuring a BEMF of the winding, and a controller coupled to the power supply circuit, the inverter and the BEMF detecting circuit and analyzing a status of the BEMF to control the BLDCM accordingly. The provided method is based on the motor winding time-sharing theory, and the controller controls the inverter to make the winding used as a driving element with loading current when the absolute value of the BEMF is relatively large and as a sensing element when the absolute value of the BEMF is relatively small.

Method and circuit for controlling sensorless single-phase BLDCM

A method for starting a motor having a stator, a rotor, a winding and an asymmetrical air gap is accomplished using several steps. The steps include: (a) providing the motor at standstill; (b) exciting the winding for a specific time period with a current impulse having a first amplitude to obtain a first specific position of the rotor with respect to the stator; (c) decreasing the first amplitude down to a second amplitude gradually by a controller to make the rotor to be positioned at a second specific position with respect to the stator after the specific time period, wherein the second amplitude is one of zero ampere and a specific value close to zero ampere, and the rotor is rotating close to the second specific position with an almost zero rotating speed when the second amplitude is reached.

Method for starting single phase BLDCM having asymmetrical air gap

The methods for starting a Hall-less single-phase BLDCM having an asymmetrical air gap are proposed. The provided methods are employed to input a specific amount of current impulse and stop the current impulse at a specific time such that the rotor of the single-phase BLDCM having an asymmetrical air gap can be realized to rotate in the pre-determined direction through one of the cogging torque and the rotor inertia after that specific time so as to accomplish the normal starting of a motor without the Hall-effect sensor.

Starting method for Hall-less single-phase BLDCM

A circuit for controlling a brushless permanent magnet motor is provided. The circuit comprises windings, each of the windings having a first end connected at a common node and each of the windings having a second end connectable directly to supply voltages by switches, the second end connected to an upper supply voltage or connected to a lower supply voltage or disconnected from the supply voltages; blocking circuitry connectable with the second ends, the blocking circuitry producing a blocked voltage; a comparator receiving the blocked voltage on one input and a reference voltage on another input, the comparator result indicating polarity of a back emf voltage in the associated winding; and a latch providing control signals for the circuit, an input of the latch enabled by an enable signal, an output of the latch comprising a back emf voltage detection signal. The blocking circuitry and the comparator are duplicated for each of the windings.

Circuit and method for controlling brushless DC motor

A method for starting-up a motor having multiple stator windings and a rotor contains first providing current to two of the windings to excite a predefined phase and allowing one of the windings floating, Then, the back electromotive force (BEMF) induced in the floating winding is monitored. If a zero crossing of BEMF occurs in the floating winding within the maximum startup time, then it commutates to the next phase, which is adjacent to the first initial phase in the predetermined sequence of excitation phases. If no zero crossing of BEMF occurs in the floating winding within the maximum startup time, then it commutates to the next phase, which is functionally shifted by two phase-intervals from the predefined phase.

Startup procedure for sensorless brushless DC motor

The invention relates to an apparatus and a method for detecting a current direction in a PWM converter or an inverter having one or more upper and lower arms, each of which consists of a switching device with an anti-parallel diode. The voltage across the switching device presents a different value and a polarity that depend on the direction of the current flowing through the switching device, wherein the current direction is acquired by sampling this voltage in the period of the trigger signal being on. In a case of small current, this sampled voltage value is relatively large to the flowing current magnitude and is easy to be distinguished. Furthermore, this invention presents a method for obtaining the phase angle between the load current and the output voltage, and judging whether the output current is zero or includes DC component. As a result, this method presents high precision.

Apparatus for detecting current direction in bridge circuits and method thereof

The invention relates to the compensation of dead time effect in electronic appliances such as inverters or converters having one or more legs with two complementary switches. The invented method mainly includes following steps providing an initial pulse width modulated (PWM) reference, providing a bias current and detecting the bias current crossing points, providing a dead time compensation signal which is adjusted responsive to the crossing points, and adding the dead time compensation signal to the PWM reference. Hence an adaptive compensation is accomplished independent of types of switching elements and load conditions. A high reliable circuit with low cost is further included as a preferred embodiment of bias current crossing points detection.

Adaptive compensation of dead time for inverter and converter

A control system operates with a PWM speed regulation of a sensorless BLDC motor with a plurality of windings. A hybrid method is present in the invention utilizing BEMF induced in stator windings to indicate the commutation instant and a falling edge detection method to override PWM chopping and commutation noises. The present invention achieves reliable sensorless rotor position detection with relative concise and low cost circuit as well as little software expense. The control device of the present invention includes a comparator for generating the BEMF zero crossing points (ZCP), and means for deriving rotor position information by detecting the falling edge (or rising edge for low-side chopping case) of the generated ZCPs.

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Shanghai, China

Zhigan Wu