Apparatus and method for detecting lock error in sensorless motor

An apparatus and a method for detecting a lock error in a sensorless motor are disclosed, where the apparatus includes a multiplexer, a negative booster, a comparator and a timer. The multiplexer can receive a coil voltage from the sensorless motor. The negative booster can receive a neutralizing voltage from the sensorless motor and drop the neutralizing voltage. The comparator can compare the coil voltage with the dropped neutralizing voltage for outputting a zero-crossing signal. The timer can count time duration during the zero-crossing signal maintained at the a logic level and determine the lock error in the sensorless motor when the time duration exceeds a predetermined period.

RELATED APPLICATIONS

This application claims priority to Taiwan Application Serial Number 98133212, filed Sep. 30, 2009, which is herein incorporated by reference.

BACKGROUND

1. Field of Invention

The present invention relates generally to an electronic device and an operating method thereof and, more particularly, to an apparatus and a method for detecting a lock error in a sensorless motor.

2. Description of Related Art

Owing to the prosperity of the industry and the commerce and the progress of the society recently, a product is designed for convenience, precision, and economy so that a present product is also better than the one before. For motors, manufacturers are unceasingly developing a sensorless motor with convenience and economy to achieve maximum results with little effort when a user manipulates the product.

It is an important technology to detect a lock error in a sensorless motor in the motor control field. However, when a lock error is detected in a sensorless motor, a deviation generated by a detecting circuit and a noise disturbance will let the detecting circuit make an incorrect determination.

As mentioned above, there are still inconveniences and defects existing in the present products, which need to be improved. Each and every manufacturer in relative art is eager to find the solution for preventing the detecting circuit from making an incorrect determination for a long time, but no solution has been found. Accordingly, how to detect a lock error in a sensorless motor precisely is an important research topic and a goal which needs to be achieved by the manufacturer in relative art currently.

SUMMARY

The present invention provides an apparatus and a method for detecting a lock error in a sensorless motor.

In one embodiment of the present invention, an apparatus for detecting a lock error in a sensorless motor comprises at least three coils converged on a neutral point. The apparatus comprises a multiplexer, a negative booster, a comparator, and a timer. The multiplexer can receive a coil voltage from one of the coils. The negative booster can receive a neutralizing voltage from the neutral point to drop the neutralizing voltage. The comparator can compare the coil voltage with the dropped neutralizing voltage to output a zero-crossing signal. When crossover occurs between the coil voltage and the dropped neutralizing voltage, the zero-crossing signal is converted from having a first logical level into having a second logical level or converted from having the second logical level into having the first logical level. The timer can count a time duration during the zero-crossing signal maintained at the first logical level and determine the lock error in the sensorless motor when the time duration exceeds a predetermined period.

As a result, the operation of dropping the neutralizing voltage overcomes a deviation generated by the comparator and a noise disturbance so that the comparator can discriminate the coil voltage from the dropped neutralizing voltage when the lock error in a sensorless motor occurs.

In another embodiment of the present invention, a method for detecting a lock error in a sensorless motor is provided, wherein the sensorless motor comprises at least three coils converged on a neutral point. The method comprises the steps of receiving a coil voltage from one of the coils, receiving a neutralizing voltage from a neutral point and dropping the neutralizing voltage, comparing the coil voltage with the dropped neutralizing voltage to output a zero-crossing voltage, wherein when crossover occurs between the coil voltage and the dropped neutralizing voltage, the zero-crossing signal is converted from having a first logical level into having a second logical level or converted from having the second logical level into having the first logical level; and counting a time duration during the zero-crossing signal maintained at the first logical level and determining the lock error in the sensorless motor when the time duration exceeds a predetermined period.

As a result, the operation of dropping the neutralizing voltage overcomes a deviation generated by the comparator and a noise disturbance so that the comparator can discriminate the coil voltage from the dropped neutralizing voltage when the lock error in a sensorless motor occurs.

In yet another embodiment of the present invention, an apparatus for detecting a lock error in a sensorless motor comprises at least three coils converged on a neutral point. The apparatus comprises a multiplexer, a negative booster, a comparator, and a timer. The multiplexer can receive a coil voltage from one of the coils. The negative booster can drop the coil voltage. The comparator can compare the neutralizing voltage of the neutral point with the dropped coil voltage to output a zero-crossing signal. When crossover occurs between the neutralizing voltage and the dropped coil voltage, the zero-crossing signal is converted from having a first logical level into having a second logical level or converted from having the second logical level into having the first logical level. The timer can count a time duration during the zero-crossing signal maintained at the first logical level and determine the lock error in the sensorless motor when the time duration exceeds a predetermined period.

As a result, the operation of dropping the neutralizing voltage overcomes a deviation generated by the comparator and a noise disturbance so that the comparator can discriminate the coil voltage from the dropped neutralizing voltage when the lock error in a sensorless motor occurs.

DETAILED DESCRIPTION

The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Certain terms that are used to describe the disclosure are discussed below, or elsewhere in the specification, to provide additional guidance to the practitioner regarding the description of the disclosure. The use of examples anywhere in this specification, including examples of any terms discussed herein, is illustrative only, and in no way limits the scope and meaning of the disclosure or of any exemplified term. Likewise, the disclosure is not limited to various embodiments given in this specification.

FIG. 1shows schematically a block diagram of an apparatus100for detecting a lock error in a sensorless motor200according to one embodiment of the present invention. As shown inFIG. 1, the sensorless motor200comprises at least three coils210,220, and230converged on a neutral point240. The apparatus100comprises a multiplexer110, a negative booster120, a comparator130, and a timer140.

In this embodiment, the multiplexer110is electrically connected to the coils210,220, and230, and the negative booster120is electrically connected to the neutral point240. The input terminal132of the comparator130is electrically connected to the multiplexer110, the input terminal134of the comparator130is electrically connected to the negative booster120, and the output terminal136of the comparator130is electrically connected to the timer140.

In addition, the multiplexer110can receive a coil voltage from one of the coils210,220, and230, and the negative booster120can receive a neutralizing voltage from the neutral point240to drop the neutralizing voltage. The comparator130can compare the coil voltage with the dropped neutralizing voltage to output a zero-crossing signal. When crossover occurs between the coil voltage and the dropped neutralizing voltage, the zero-crossing signal is converted from having a first logical level into having a second logical level or converted from having the second logical level into having the first logical level. The timer140can count a time duration during the zero-crossing signal maintained at the first logical level and determine the lock error in the sensorless motor200when the time duration exceeds a predetermined period.

As a result, the operation of dropping the neutralizing voltage overcomes a deviation generated by the comparator130and a noise disturbance so that the comparator130can discriminate the coil voltage from the dropped neutralizing voltage when the lock error in the sensorless motor occurs.

In this embodiment, the first logical level can be a logical high level, and the second logical level can be a logical low level. The apparatus100determines the lock error in the sensorless motor200when the time duration during the zero-crossing signal maintained at the high logical level exceeds a predetermined period.

Furthermore, the predetermined time duration depends on a rotational speed of the sensorless motor200. The predetermined time duration becomes shorter when the rotational speed becomes faster, and the predetermined time duration becomes longer when the rotational speed becomes slower. A person with ordinary skill in the art can flexibly determine the predetermined time duration according to actual demand.

As shown inFIG. 1, the apparatus100further comprises a decoder150. The decoder150is electrically connected to the multiplexer110and the timer140. The decoder150can make the multiplexer110select one of the coils210,220, and230and make the timer140start to count the time duration during the zero-crossing signal maintained at the first logical level after the coil is selected. Therefore, the decoder150can control the multiplexer110and the timer140to perform a corresponding operation timely.

Moreover, the negative booster120comprises a first voltage divider122and a second voltage divider124. The first voltage divider122is electrically connected to the neutral point240, and the second voltage divider124is connected to the first voltage divider122in series, wherein the position at which the first voltage divider122and the second voltage divider124are connected to each other is electrically connected to the comparator130.

Specifically, each of the first voltage divider122and the second voltage divider124can be a resistor for dropping the voltage. The resistance of the first voltage divider122and the second voltage divider124can be decided by a deviation generated by the comparator130and a noise disturbance so that the degree of the dropped neutralizing voltage is enough for the comparator to discriminate the coil voltage from the dropped neutralizing voltage when the lock error in a sensorless motor200occurs. For example, the resistance of the first voltage divider122is 1 kΩ, and the resistance of the second voltage divider124is 100 kΩ.

FIG. 2shows schematically a voltage oscillogram for the comparator shown inFIG. 1when no lock error occurs in the sensorless motor. As shown inFIG. 2, the crossover occurs between the voltage of the input terminal134of the comparator130and the voltage of the input terminal132of the comparator130in the interval340, and the zero-crossing signal outputted from the output terminal136of the comparator130is converted from having the low logical level320into having the high logical level322in the zero-crossing point310. The crossover also occurs between the voltage of the input terminal134of the comparator130and the voltage of the input terminal132of the comparator130in the interval342, and the zero-crossing signal outputted from the output terminal136of the comparator130is converted from having the high logical level322into having the low logical level320in the zero-crossing point312.

FIG. 3shows schematically a voltage oscillogram for the comparator shown inFIG. 1when the lock error occurs in the sensorless motor. As shown inFIG. 3, the voltage of the input terminal134of the comparator130is maintained at the low logical level in the interval340and342. The crossover occurs between the voltage of the input terminal134of the comparator130and the voltage of the input terminal132of the comparator130in the zero-crossing point330, and the zero-crossing signal outputted from the output terminal136of the comparator130is converted from having the low logical level350into having the high logical level352. The crossover occurs between the voltage of the input terminal134of the comparator130and the voltage of the input terminal132of the comparator130in the zero-crossing point332, and the zero-crossing signal outputted from the output terminal136of the comparator130is converted from having the high logical level352into having the low logical level350.

In addition, no matter whether the sensorless motor200has a lock error, the waveforms of the coil voltage and the neutralizing voltage thereof are known knowledge for those skilled in the art and not the claimed scope of this invention so that there is no need to give unnecessary details herein.

It is noteworthy that if there is no negative booster120inFIG. 1, that is to say, the neutral point240can be electrically connected to the input terminal134of the comparator130directly. When a lock error is detected in the sensorless motor, the neutralizing voltage of the neutral point240and the coil voltage in the intervals340and342are almost the same because of the counter electromotive force being zero. In other words, the voltage of the input terminal134and the voltage of the input terminal132in the interval340and342are supposed to be nearly the same in theory, but the deviation generated by the comparator130and a noise disturbance make the voltage of the input terminal134become higher or lower than the voltage of the input terminal132so that the comparator130may probably make an incorrect determination.

Therefore, the negative booster120arranged in the apparatus110can drop the neutralizing voltage of the neutral point240so that the comparator130can discriminate the coil voltage from the dropped neutralizing voltage when a lock error in a sensorless motor occurs, for determining the lock error in the sensorless motor, when the time duration during the zero-crossing signal maintained at the same logical level exceeds a predetermined period.

FIG. 4shows schematically a flow diagram of a method for detecting a lock error in a sensorless motor according to another embodiment of the present invention. As shown inFIG. 4, the sensorless motor comprises at least three coils converged on a neutral point, and the method comprises the steps410,420,430, and440(it should be noted that the sequence of the steps according to the embodiment of the present invention can be adjusted due to actual demand if not expressly stated. Moreover, all or part of the steps according to the embodiment of the present invention can be performed simultaneously.)

The method comprises the steps of receiving a coil voltage from one of the coils (step410), receiving a neutralizing voltage from a neutral point and dropping the neutralizing voltage (step420), comparing the coil voltage with the dropped neutralizing voltage to output a zero-crossing voltage, wherein when crossover occurs between the coil voltage and the dropped neutralizing voltage, the zero-crossing signal is converted from having a first logical level into having a second logical level or converted from having the second logical level into having the first logical level (step430); and counting a time duration during the zero-crossing signal maintained at the first logical level and determining the lock error in the sensorless motor when the time duration exceeds a predetermined period (step440).

As a result, the operation of dropping the neutralizing voltage overcomes a deviation generated by the comparator and a noise disturbance so that the comparator can discriminate the coil voltage from the dropped neutralizing voltage when the lock error in a sensorless motor occurs.

The first logical level at a high logical level is different from the second logical level. For example, the first logical level is the high logical level, and the second logical level is a low logical level. The method400determines the lock error in the sensorless motor600when the time duration during the zero-crossing signal maintained at the high logical level exceeds a predetermined period.

At step410, a coil can be selected from the coils, and the coil voltage can be received from the selected coil after the coil is selected. At step430, the time duration during the zero-crossing signal maintained at the first logical level can be counted after the coil is selected. As a result, the step410and the step430can be performed correspondingly.

Moreover, the hardware device for implementing the foregoing steps have been mentioned in the preceding embodiment so that there is no need to give unnecessary details herein.

FIG. 5shows schematically a block diagram of an apparatus500for detecting a lock error in a sensorless motor600according to yet another embodiment of the present invention. The sensorless motor600comprises at least three coils610,620, and630converged on a neutral point640. The apparatus comprises a multiplexer510, a negative booster520, a comparator530, and a timer540.

In this embodiment, the multiplexer510is electrically connected to the coils610,620, and630, the negative booster520is electrically connected to the multiplexer510, the negative booster520and the neutral point640are electrically connected to the comparator530respectively, and the timer540is electrically connected to the comparator530.

The multiplexer510can receive a coil voltage from one of the coils610,620, and630, and negative booster520can drop the coil voltage. The comparator530can compare the neutralizing voltage of the neutral point with the dropped coil voltage to output a zero-crossing signal. When crossover occurs between the neutralizing voltage and the dropped coil voltage, the zero-crossing signal is converted from having a first logical level into having a second logical level or converted from having the second logical level into having the first logical level. The timer540can count a time duration during the zero-crossing signal maintained at the first logical level and determine the lock error in the sensorless motor600when the time duration exceeds a predetermined period.

As a result, the operation of dropping the coil voltage overcomes a deviation generated by the comparator530and a noise disturbance so that the comparator530can discriminate the neutralizing voltage from the dropped coil voltage when the lock error in a sensorless motor occurs.

The first logical level is different from the second logical level. The apparatus500determines the lock error in the sensorless motor600when the time duration during the zero-crossing signal maintained at the high logical level exceeds a predetermined period.

Furthermore, the predetermined time duration depends on a rotational speed of the sensorless motor600. The predetermined time duration becomes shorter when the rotational speed becomes faster while the predetermined time duration becomes longer when the rotational speed becomes slower. A person with ordinary skill in the art can flexibly determine the predetermined time duration according to actual demand.

As shown inFIG. 5, the apparatus500further comprises a decoder550. The decoder550is electrically connected to the multiplexer510and the timer540. The decoder550can make the multiplexer510select one of the coils610,620, and630and make the timer540start to count the time duration during the zero-crossing signal maintained at the first logical level after the coil is selected. Therefore, the decoder550can control the multiplexer510and the timer540to perform corresponding operation timely.

The negative booster520comprises a first voltage divider522and a second voltage divider524. The first voltage divider522is electrically connected to the multiplexer510, and the second voltage divider524is connected to the first voltage divider522in series, wherein the position at which the first voltage divider522and the second voltage divider524are connected to each other is electrically connected to the comparator530.

Specifically, each of the first voltage divider522and the second voltage divider524can be a resistor for dropping the coil voltage. The resistance of the first voltage divider522and the second voltage divider524is decided by a deviation generated by the comparator530and a noise disturbance so that the degree of the dropped coil voltage is enough for the comparator530discriminating the neutralizing voltage from the dropped coil voltage when the lock error in the sensorless motor600occurs. For example, the resistance of the first voltage divider522is 1 kΩ, and the resistance of the second voltage divider524is 100 kΩ.