CN110707979B - Motor rotation speed detection device, detection method, motor system and air conditioner - Google Patents
Motor rotation speed detection device, detection method, motor system and air conditioner Download PDFInfo
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- CN110707979B CN110707979B CN201910997723.6A CN201910997723A CN110707979B CN 110707979 B CN110707979 B CN 110707979B CN 201910997723 A CN201910997723 A CN 201910997723A CN 110707979 B CN110707979 B CN 110707979B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/18—Estimation of position or speed
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24F—AIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
- F24F11/00—Control or safety arrangements
- F24F11/88—Electrical aspects, e.g. circuits
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01P—MEASURING LINEAR OR ANGULAR SPEED, ACCELERATION, DECELERATION, OR SHOCK; INDICATING PRESENCE, ABSENCE, OR DIRECTION, OF MOVEMENT
- G01P3/00—Measuring linear or angular speed; Measuring differences of linear or angular speeds
- G01P3/42—Devices characterised by the use of electric or magnetic means
- G01P3/44—Devices characterised by the use of electric or magnetic means for measuring angular speed
- G01P3/48—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage
- G01P3/481—Devices characterised by the use of electric or magnetic means for measuring angular speed by measuring frequency of generated current or voltage of pulse signals
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/24—Vector control not involving the use of rotor position or rotor speed sensors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
- H02P25/022—Synchronous motors
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P2207/00—Indexing scheme relating to controlling arrangements characterised by the type of motor
- H02P2207/05—Synchronous machines, e.g. with permanent magnets or DC excitation
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- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The invention provides a motor rotating speed detection device, a motor rotating speed detection method, a motor system and an air conditioner. Wherein, motor speed detection device includes: the voltage detection circuit is connected with the motor and is configured to detect any two line voltages of the motor and superpose the any two line voltages to obtain a first voltage; a voltage conversion circuit connected with the voltage detection circuit, the voltage conversion circuit configured to convert the first voltage into a second voltage; and the processing component is connected with the voltage conversion circuit and is configured to acquire the rotating speed according to the second voltage. By the technical scheme, cost increase caused by voltage measurement by using an encoder can be avoided, and rotating speed detection failure caused by a certain phase disconnection can be avoided.
Description
Technical Field
The invention relates to the technical field of motors, in particular to a motor rotating speed detection device, a motor rotating speed detection method, a motor system and an air conditioner.
Background
The closed-loop vector control has the characteristics of high control precision and good rotating speed control and is widely applied to a driving system of a synchronous motor. The closed-loop vector control needs to accurately sample the current rotating speed of the motor, and in the related art, the accurate measurement of the rotating speed is realized by adding an encoder, so that the method increases the system cost.
Disclosure of Invention
The present invention is directed to solving at least one of the problems of the prior art or the related art.
To this end, an aspect of the present invention is to provide a motor rotation speed detection apparatus.
Another aspect of the present invention is to provide a method for detecting a rotational speed of a motor.
Yet another aspect of the present invention is to provide an electric machine system.
Yet another aspect of the present invention is to provide an air conditioner.
In view of the above, according to one aspect of the present invention, there is provided a motor rotation speed detecting apparatus including: the voltage detection circuit is connected with the motor and is configured to detect any two line voltages of the motor and superpose the any two line voltages to obtain a first voltage; a voltage conversion circuit connected with the voltage detection circuit, the voltage conversion circuit configured to convert the first voltage into a second voltage; and the processing component is connected with the voltage conversion circuit and is configured to acquire the rotating speed according to the second voltage.
The invention provides a motor rotating speed detection device which comprises a voltage detection circuit, a voltage conversion circuit and a processing assembly. The three-phase voltage A, B, C of the motor is combined in pairs to obtain three groups of voltage combinations AB, AC and BC, the voltage detection circuit selects two groups of the three-phase voltages A, B, C to detect line voltages, for example, the line voltages of Vab and Vac are detected, the line voltages are filtered and then are compositely superposed to synthesize a sinusoidal voltage with the rotating speed frequency of the motor, namely, a first voltage, so that even if one phase (B phase or C phase) is disconnected, the output of the part of the circuit is 0V, and the other part of the circuit normally outputs and can normally work. The sinusoidal voltage is converted into a square wave voltage, i.e., a second voltage, using a voltage conversion circuit. And further, the processing component performs software algorithm operation according to the second voltage to obtain the rotating speed. Through the technical scheme of the invention, the cost increase caused by using the encoder to measure the voltage can be avoided, and the rotating speed detection failure caused by the disconnection of a certain phase (a non-node phase, for example, the phase A is a node phase) can be avoided.
The motor rotation speed detection device according to the present invention may further include the following features:
in the above technical solution, the converting the first voltage into the second voltage by the voltage converting circuit specifically includes: the first voltage is compared with a voltage threshold value to convert the first voltage into a second voltage, wherein the voltage threshold value is inversely related to the frequency of the first voltage.
In the technical scheme, the voltage conversion circuit sets a dynamic voltage threshold value for limiting level inversion, and compares a sinusoidal voltage with the voltage threshold value to convert the sinusoidal voltage into a square wave voltage, wherein the voltage threshold value is inversely related to the frequency of the first voltage. According to the requirement of motor control, the high-frequency time-base wave voltage is high, and the low-frequency time-base wave voltage is low. The voltage is high at high frequency, and a lower voltage threshold is set to perform level inversion on the high voltage, so that the detection speed and precision at high frequency are improved. There are more low-voltage during the low frequency, also there are more small wave forms promptly, these small wave forms are the interference, set for higher voltage threshold value during the low frequency, filter the low-voltage and do not carry out the level upset, and then guarantee to have sufficient interference killing feature under the low frequency, improve the waveform quality.
In any of the above technical solutions, the voltage conversion circuit is an integration circuit.
In this solution, the voltage conversion circuit may be implemented on the basis of an integration circuit. The frequency response function of the integration circuit is 1/(ω RC), where ω denotes frequency, R denotes resistance, C denotes capacitance, and low frequency has a high transmission ratio, meaning a high voltage threshold, and high frequency has a low transmission ratio, meaning a low voltage threshold. Compared with the prior art in which only one fixed voltage threshold is set, the method and the device realize setting of different voltage thresholds under different frequencies through the integrating circuit, namely setting of dynamic voltage thresholds, and further can improve the anti-interference capability under low frequency and improve the detection speed and detection precision under high frequency.
In any of the above technical solutions, the method further includes: an isolation component connected between the voltage conversion circuit and the processing component, the isolation component configured to isolate the second voltage from other voltages of the motor.
In the technical scheme, on one hand, the motor rotating speed detection device is connected in a motor main loop and belongs to a strong power side on safety regulations, and the isolation assembly is adopted to improve the safety level. On the other hand, the output of the motor driver is high-frequency pulse waves, which contain a large amount of rapid pulses and are easy to interfere with signals, and the anti-interference capability of the signals can be enhanced by adopting the isolation component to electrically isolate the primary side circuit.
In any of the above technical solutions, the method further includes: and the amplifying circuit is connected between the isolation assembly and the processing assembly and is configured to amplify the second voltage.
In the technical scheme, the amplifying circuit is used for amplifying the second voltage, so that the influence on detection caused by small signals is avoided.
According to another aspect of the present invention, a method for detecting a rotation speed of a motor is provided, including: acquiring any two line voltages of a motor, and superposing the any two line voltages to acquire a first voltage; converting the first voltage into a second voltage; and acquiring the rotating speed according to the second voltage.
According to the motor rotating speed detection method provided by the invention, three-phase voltage A, B, C of the motor is combined in any two pairs to obtain three groups of voltage combinations AB, AC and BC, two groups of the three-phase voltage A, B, C are selected to carry out line voltage detection, for example, line voltages of Vab and Vac are detected, and are subjected to filtering and then are subjected to composite superposition to synthesize a sinusoidal voltage with the rotating speed frequency of the motor, namely a first voltage, so that even if a certain phase (B phase or C phase) is disconnected, the output of the part of circuit is 0V, and the other part of circuit normally outputs and can also normally work. And further, converting the sinusoidal voltage into a square wave voltage, namely a second voltage, and performing software algorithm operation according to the second voltage to obtain the rotating speed. Through the technical scheme of the invention, the cost increase caused by using the encoder to measure the voltage can be avoided, and the rotating speed detection failure caused by the disconnection of a certain phase (a non-node phase, for example, the phase A is a node phase) can be avoided.
The method for detecting the rotating speed of the motor can also have the following technical characteristics:
in the above technical solution, the step of converting the first voltage into the second voltage specifically includes: the first voltage is compared with a voltage threshold value to convert the first voltage into a second voltage, wherein the voltage threshold value is inversely related to the frequency of the first voltage.
In the technical scheme, a dynamic voltage threshold is set for limiting level inversion, a sinusoidal voltage and the voltage threshold are compared and converted into a square wave voltage, and the voltage threshold is inversely related to the frequency of the first voltage. According to the requirement of motor control, the high-frequency time-base wave voltage is high, and the low-frequency time-base wave voltage is low. The voltage is high at high frequency, and a lower voltage threshold is set to perform level inversion on the high voltage, so that the detection speed and precision at high frequency are improved. There are more low-voltage during the low frequency, also there are more small wave forms promptly, these small wave forms are the interference, set for higher voltage threshold value during the low frequency, filter the low-voltage and do not carry out the level upset, and then guarantee to have sufficient interference killing feature under the low frequency, improve the waveform quality.
In some embodiments, the dynamic voltage threshold may be set by using an integration circuit, where the frequency response function of the integration circuit is 1/(ω RC), where ω denotes frequency, R denotes resistance, and C denotes capacitance, and the transmission ratio at low frequency is high, meaning that the voltage threshold is high, and the transmission ratio at high frequency is low, meaning that the voltage threshold is low. Compared with the prior art in which only one fixed voltage threshold is set, the method and the device realize setting of different voltage thresholds under different frequencies through the integrating circuit, namely setting of dynamic voltage thresholds, and further can improve the anti-interference capability under low frequency and improve the detection speed and detection precision under high frequency.
In any of the above technical solutions, before obtaining the rotation speed according to the second voltage, the method further includes: the second voltage is isolated from other voltages of the motor.
In the technical scheme, on one hand, the motor rotating speed detection device is connected in a motor main loop and belongs to a strong power side on safety regulations, and the isolation assembly is adopted to improve the safety level. On the other hand, the output of the motor driver is high-frequency pulse waves, which contain a large amount of rapid pulses and are easy to interfere with signals, and the anti-interference capability of the signals can be enhanced by adopting the isolation component to electrically isolate the primary side circuit.
In any of the above technical solutions, before obtaining the rotation speed according to the second voltage, the method further includes: the second voltage is amplified.
In the technical scheme, the amplifying circuit is used for amplifying the second voltage, so that the influence on detection caused by small signals is avoided.
According to yet another aspect of the present invention, there is provided a motor system, including a motor; the motor rotating speed detection device according to any one of the above technical schemes.
The motor system provided by the invention comprises the motor rotating speed detection device of any one of the technical schemes, so that all beneficial technical effects of the motor rotating speed detection device of any one of the technical schemes can be realized.
According to another aspect of the present invention, an air conditioner is provided, comprising a motor rotation speed detecting device according to any one of the above technical solutions; or a motor system as described above.
The air conditioner provided by the invention comprises a motor rotating speed detection device according to any one of the technical schemes; or the motor system as described above, it is therefore possible to achieve all the advantageous technical effects of the motor speed detection device according to any one of the above-described technical solutions or the motor system as described above.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
fig. 1 is a schematic view showing a motor rotation speed detecting apparatus according to a first embodiment of the present invention;
fig. 2 is a schematic view showing a motor rotation speed detecting apparatus according to a second embodiment of the present invention;
fig. 3 is a schematic view showing a motor rotation speed detecting apparatus according to a third embodiment of the present invention;
FIG. 4 shows a schematic diagram of a three-phase voltage composite detection circuit of an embodiment of the invention;
FIG. 5 shows a schematic diagram of a dynamic threshold circuit of an embodiment of the invention;
Fig. 6 is a flowchart illustrating a motor rotation speed detection method according to a first embodiment of the present invention;
fig. 7 is a schematic flow chart showing a motor rotation speed detection method according to a second embodiment of the present invention;
fig. 8 is a flowchart illustrating a motor rotation speed detection method according to a third embodiment of the present invention.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, a more particular description of the invention will be rendered by reference to the appended drawings. It should be noted that the embodiments of the present invention and features of the embodiments may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the scope of the present invention is not limited to the specific embodiments disclosed below.
An embodiment of the first aspect of the present invention provides a motor rotation speed detection device, which is described in detail by the following embodiments.
First embodiment, fig. 1 shows a schematic diagram of a motor rotation speed detection apparatus according to a first embodiment of the present invention. Wherein, this motor speed detection device 100 includes:
The voltage detection circuit 102 is connected with the motor, and the voltage detection circuit 102 is configured to detect any two line voltages of the motor and superpose any two line voltages to obtain a first voltage;
a voltage conversion circuit 104 connected to the voltage detection circuit 102, the voltage conversion circuit 104 being configured to convert the first voltage into a second voltage;
and a processing component 106 connected to the voltage converting circuit 104, wherein the processing component 106 is configured to obtain the rotation speed according to the second voltage.
The motor speed detection device 100 provided by the invention comprises a voltage detection circuit 102, a voltage conversion circuit 104 and a processing component 106. The three-phase voltage A, B, C of the motor is combined in any two pairs to obtain three groups of voltage combinations AB, AC and BC, the voltage detection circuit 102 selects two groups of the three-phase voltages to detect line voltages, for example, the line voltages of Vab and Vac are detected, the line voltages are filtered and then are compositely superposed to synthesize a sinusoidal voltage with the rotating speed frequency of the motor, namely, a first voltage, so that even if one phase in the B phase or the C phase is disconnected, the output of the part of the circuit is 0V, and the other part of the circuit normally outputs and can normally work. The sinusoidal voltage is converted into a square wave voltage, i.e., a second voltage, by the voltage conversion circuit 104. Further, the processing component 106 performs software algorithm operation according to the second voltage to obtain the rotation speed. Through the technical scheme of the invention, the cost increase caused by using the encoder to measure the voltage can be avoided, and the rotating speed detection failure caused by the disconnection of a certain phase (a non-node phase, for example, the phase A is a node phase) can be avoided.
In the above embodiment, the converting the first voltage into the second voltage by the voltage converting circuit 104 specifically includes: the first voltage is compared with a voltage threshold value to convert the first voltage into a second voltage, wherein the voltage threshold value is inversely related to the frequency of the first voltage.
In this embodiment, the voltage conversion circuit 104 sets a dynamic voltage threshold for level-flipping limiting, converting a sinusoidal voltage to a square wave voltage in comparison to a voltage threshold that is inversely related to the frequency of the first voltage. According to the requirement of motor control, the high-frequency time-base wave voltage is high, and the low-frequency time-base wave voltage is low. The voltage is high at high frequency, and a lower voltage threshold is set to perform level inversion on the high voltage, so that the detection speed and precision at high frequency are improved. There are more low-voltage during the low frequency, also there are more small wave forms promptly, these small wave forms are the interference, set for higher voltage threshold value during the low frequency, filter the low-voltage and do not carry out the level upset, and then guarantee to have sufficient interference killing feature under the low frequency, improve the waveform quality.
In the above embodiment, the voltage conversion circuit 104 is an integration circuit.
In this embodiment, the voltage conversion circuit 104 may be implemented on the basis of an integration circuit. The frequency response function of the integration circuit is 1/(ω RC), where ω denotes frequency, R denotes resistance, C denotes capacitance, and low frequency has a high transmission ratio, meaning a high voltage threshold, and high frequency has a low transmission ratio, meaning a low voltage threshold. Compared with the prior art in which only one fixed voltage threshold is set, the method and the device realize setting of different voltage thresholds under different frequencies through the integrating circuit, namely setting of dynamic voltage thresholds, and further can improve the anti-interference capability under low frequency and improve the detection speed and detection precision under high frequency.
Second embodiment, fig. 2 is a schematic diagram showing a motor rotation speed detecting apparatus according to a second embodiment of the present invention. Wherein, this motor speed detection device 100 includes:
the voltage detection circuit 102 is connected with the motor, and the voltage detection circuit 102 is configured to detect any two line voltages of the motor and superpose any two line voltages to obtain a first voltage;
a voltage conversion circuit 104 connected to the voltage detection circuit 102, the voltage conversion circuit 104 being configured to convert the first voltage into a second voltage;
the processing component 106 is connected with the voltage conversion circuit 104, and the processing component 106 is configured to obtain a rotating speed according to the second voltage;
an isolation component 108 connected between the voltage conversion circuit 104 and the processing component 106, the isolation component 108 configured to isolate the second voltage from other voltages of the motor.
In this embodiment, on one hand, since the motor speed detection device 100 is connected in the main circuit of the motor, which belongs to the heavy current side in terms of safety, the isolation assembly 108 can be used to improve the safety level. On the other hand, the output of the motor driver is a high-frequency pulse wave, which contains a large amount of fast pulses and is easy to interfere with signals, and the anti-interference capability of the signals can be enhanced by adopting the isolation component 108 to electrically isolate from the primary side circuit.
The isolation means of the isolation component can be optical isolation or magnetic isolation.
The converting the first voltage into the second voltage by the voltage converting circuit 104 specifically includes: the voltage conversion circuit 104 may be an integrating circuit that compares the first voltage with a voltage threshold that is inversely related to a frequency of the first voltage to convert the first voltage into a second voltage.
Third embodiment, fig. 3 is a schematic diagram showing a motor rotation speed detection apparatus according to a third embodiment of the present invention. Wherein, this motor speed detection device 100 includes:
the voltage detection circuit 102 is connected with the motor, and the voltage detection circuit 102 is configured to detect any two line voltages of the motor and superpose any two line voltages to obtain a first voltage;
a voltage conversion circuit 104 connected to the voltage detection circuit 102, the voltage conversion circuit 104 being configured to convert the first voltage into a second voltage;
the processing component 106 is connected with the voltage conversion circuit 104, and the processing component 106 is configured to obtain a rotating speed according to the second voltage;
an isolation component 108 connected between the voltage conversion circuit 104 and the processing component 106, the isolation component 108 configured to isolate the second voltage from other voltages of the motor;
And an amplifying circuit 110 connected between the isolation component 108 and the processing component 106, wherein the amplifying circuit 110 is configured to amplify the second voltage.
In the embodiment, the amplifying circuit is used for amplifying the second voltage, so that the influence of a small signal on detection is avoided. The converting the first voltage into the second voltage by the voltage converting circuit 104 specifically includes: the voltage conversion circuit 104 may be an integrating circuit that compares the first voltage with a voltage threshold that is inversely related to a frequency of the first voltage to convert the first voltage into a second voltage.
The embodiment four provides a three-phase synchronous machine rotational speed detection circuit, can reduce control system cost, improves closed-loop control performance, detects and includes: (1) and any two line voltages are combined after being detected by the three-phase voltage composite detection circuit, and a virtual voltage with the same frequency as the rotating speed is fitted. (2) And the dynamic threshold circuit designs voltage thresholds at different frequencies based on the frequency domain characteristics of the integrating circuit. (3) And the output circuit improves the anti-interference capability of the digital signal through the isolation optocoupler and the isolation power supply.
(1) Three-phase voltage composite detection circuit
As shown in fig. 4, the three-phase voltage composite detection circuit includes a first adder 402, a second adder 404, and a third adder 406, any two of the three-phase voltages are combined, two groups of the three-phase voltages are selected for detection, for example, AB and AC are used to detect line voltages of Va and Vb, and Va and Vc, respectively, and after filtering, the three-phase voltages are combined to finally synthesize a sinusoidal voltage Vo having the same frequency as the motor speed. And carrying out waveform processing by taking the sinusoidal voltage Vo as a reference to obtain a rotating speed signal. Even if one of the B phase or the C phase is disconnected, the output of the circuit is 0, and the other circuit can normally work.
(2) Dynamic threshold circuit
The output of the motor driving power supply is regular pulse voltage, according to the requirement of motor control, the high-frequency time base wave voltage is high, the low-frequency time base wave voltage is low, and the change of frequency and amplitude value brings challenges to the rotating speed detection. For this purpose, a dynamic threshold circuit is designed, which is implemented on the basis of an integrating circuit, as shown in fig. 5. The frequency response function of the integrating circuit is 1/(omega RC), the transmission ratio is high at low frequency, which means that the voltage threshold is high, and therefore the anti-interference capability is improved. The low transmission ratio at high frequencies means that the voltage threshold is low, thereby improving detection speed and accuracy at high frequencies.
(3) Output circuit
The input is connected in the main loop of the motor, which belongs to the strong current side on the safety standard, and the output signal adopts the isolation circuit to improve the safety level. Meanwhile, the output of the motor driver is high-frequency pulse waves, a large number of rapid pulses are contained, interference on signals is easy to generate, and the motor driver is electrically isolated from a primary side circuit by adopting an isolation circuit, so that the anti-interference capability of the signals can be enhanced.
The embodiment of the second aspect of the present invention provides a method for detecting a rotational speed of a motor, which is described in detail by the following embodiments.
First embodiment, fig. 6 is a schematic flow chart illustrating a motor speed detection method according to a first embodiment of the present invention. The motor rotating speed detection method comprises the following steps:
and 606, acquiring the rotating speed according to the second voltage.
According to the motor rotating speed detection method provided by the invention, three-phase voltage A, B, C of the motor is combined in any two pairs to obtain three groups of voltage combinations AB, AC and BC, two groups of the three-phase voltage A, B, C are selected to carry out line voltage detection, for example, line voltages of Vab and Vac are detected, and are subjected to filtering and then are subjected to composite superposition to synthesize a sinusoidal voltage with the rotating speed frequency of the motor, namely a first voltage, so that even if a certain phase (B phase or C phase) is disconnected, the output of the part of circuit is 0V, and the other part of circuit normally outputs and can also normally work. And further, converting the sinusoidal voltage into a square wave voltage, namely a second voltage, and performing software algorithm operation according to the second voltage to obtain the rotating speed. Through the technical scheme of the invention, the cost increase caused by using the encoder to measure the voltage can be avoided, and the rotating speed detection failure caused by the disconnection of a certain phase (a non-node phase, for example, the phase A is a node phase) can be avoided.
In the above embodiment, the step of converting the first voltage into the second voltage specifically includes: the first voltage is compared with a voltage threshold value to convert the first voltage into a second voltage, wherein the voltage threshold value is inversely related to the frequency of the first voltage.
In this embodiment, a dynamic voltage threshold is set for level-reversal limiting, and a sinusoidal voltage is compared with a voltage threshold, which is inversely related to the frequency of the first voltage, and converted into a square-wave voltage. According to the requirement of motor control, the high-frequency time-base wave voltage is high, and the low-frequency time-base wave voltage is low. The voltage is high at high frequency, and a lower voltage threshold is set to perform level inversion on the high voltage, so that the detection speed and precision at high frequency are improved. There are more low-voltage during the low frequency, also there are more small wave forms promptly, these small wave forms are the interference, set for higher voltage threshold value during the low frequency, filter the low-voltage and do not carry out the level upset, and then guarantee to have sufficient interference killing feature under the low frequency, improve the waveform quality.
In some embodiments, the dynamic voltage threshold may be set using an integration circuit whose frequency response function is 1/(ω RC), where ω represents frequency, R represents resistance, C represents capacitance, and low frequency is high, meaning the voltage threshold is high, and high frequency is low, meaning the voltage threshold is low. Compared with the prior art in which only one fixed voltage threshold is set, the method and the device realize setting of different voltage thresholds under different frequencies through the integrating circuit, namely setting of dynamic voltage thresholds, and further can improve the anti-interference capability under low frequency and improve the detection speed and detection precision under high frequency.
Second embodiment, fig. 7 is a schematic flow chart illustrating a motor speed detection method according to a second embodiment of the present invention. The motor rotating speed detection method comprises the following steps:
and step 708, acquiring the rotating speed according to the second voltage.
In this embodiment, on one hand, since the motor speed detection device is connected in the motor main loop and belongs to the strong current side on the safety regulation, the safety level can be improved by adopting the isolation assembly. On the other hand, the output of the motor driver is high-frequency pulse waves, which contain a large amount of rapid pulses and are easy to interfere with signals, and the anti-interference capability of the signals can be enhanced by adopting the isolation component to electrically isolate the primary side circuit.
Third embodiment, fig. 8 is a schematic flow chart illustrating a motor speed detection method according to a third embodiment of the present invention. The motor rotating speed detection method comprises the following steps:
and step 810, acquiring the rotating speed according to the second voltage.
In the embodiment, the amplifying circuit is used for amplifying the second voltage, so that the influence of a small signal on detection is avoided.
In an embodiment of the third aspect of the present invention, a motor system is provided, which includes a motor; the motor rotation speed detection device according to any one of the above embodiments.
The motor system provided by the invention comprises the motor rotating speed detection device of any one of the embodiments, so that all beneficial technical effects of the motor rotating speed detection device of any one of the embodiments can be realized.
In an embodiment of a fourth aspect of the present invention, an air conditioner is provided, including the motor rotation speed detection apparatus according to any of the above embodiments; or a motor system as described above.
The air conditioner provided by the invention comprises a motor rotating speed detection device of any one of the embodiments; or the motor system as described above, it is therefore possible to achieve all the advantageous technical effects of the motor rotation speed detection apparatus as described in any of the above embodiments or the motor system as described above.
In the description herein, the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance unless explicitly stated or limited otherwise; the terms "connected," "mounted," "secured," and the like are to be construed broadly and include, for example, fixed connections, removable connections, or integral connections; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
In the description herein, the description of the terms "one embodiment," "some embodiments," "specific embodiments," etc., means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. A motor rotation speed detecting apparatus, characterized by comprising:
the voltage detection circuit is connected with the motor and is configured to detect any two line voltages of the motor and superpose the any two line voltages to obtain a first voltage;
a voltage conversion circuit connected with the voltage detection circuit, the voltage conversion circuit configured to convert the first voltage into a second voltage;
the processing component is connected with the voltage conversion circuit and is configured to acquire the rotating speed according to the second voltage;
the voltage conversion circuit converts the first voltage into a second voltage, and specifically includes:
comparing the first voltage to a voltage threshold to convert the first voltage to the second voltage, wherein the voltage threshold is inversely related to a frequency of the first voltage, the voltage conversion circuit being an integrating circuit.
2. The motor rotation speed detecting device according to claim 1, further comprising:
an isolation component connected between the voltage conversion circuit and the processing component, the isolation component configured to isolate the second voltage from other voltages of the motor.
3. The motor rotation speed detecting apparatus according to claim 2, further comprising:
an amplification circuit connected between the isolation component and the processing component, the amplification circuit configured to amplify the second voltage.
4. A motor rotation speed detection method is characterized by comprising the following steps:
detecting any two line voltages of the motor, and superposing the any two line voltages to obtain a first voltage;
converting the first voltage to a second voltage;
acquiring the rotating speed according to the second voltage;
the step of converting the first voltage into the second voltage specifically includes:
comparing the first voltage to a voltage threshold that is inversely related to a frequency of the first voltage, the voltage threshold being set with an integrating circuit, thereby converting the first voltage to the second voltage.
5. The motor rotation speed detection method according to claim 4, further comprising, before acquiring the rotation speed from the second voltage:
isolating the second voltage from other voltages of the motor.
6. The motor rotation speed detection method according to claim 4, further comprising, before acquiring the rotation speed from the second voltage:
amplifying the second voltage.
7. An electric machine system, comprising:
a motor;
a motor rotation speed detecting apparatus according to any one of claims 1 to 3.
8. An air conditioner, comprising:
a motor rotation speed detection apparatus according to any one of claims 1 to 3; or
The electric motor system set forth in claim 7.
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| CN101976994A (en) * | 2010-09-17 | 2011-02-16 | 三一重工股份有限公司 | Conversion circuit, method and system for detecting phase sequence of three-phase power supply, and motor |
| JP6150212B2 (en) * | 2013-08-18 | 2017-06-21 | 有限会社シー・アンド・エス国際研究所 | Digital rotor phase speed estimation device for AC motor |
| CN108964560A (en) * | 2018-07-19 | 2018-12-07 | 常州市凯迪电器股份有限公司 | Brush direct current motor rotational speed extraction method and its circuit |
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