Half-bridge drive brushless direct current motor back electromotive force position detection system

Abstract

The invention discloses a back electromotive force position detection system of a half-bridge drive brushless direct current motor, and belongs to the field of high-speed motor sensorless control. The system comprises a line voltage comparison unit, a digital filtering unit and a falling edge obtaining unit which are electrically connected in sequence, the line voltage comparison unit is electrically connected with a motor three-phase winding, and the line voltage comparison unit is used for comparing terminal voltages of the motor three-phase winding pairwise to obtain three-phase initial position detection signals; the digital filtering unit is used for carrying out edge filtering processing on the three-phase initial position detection signal according to the filtering time to obtain a three-phase filtering position detection signal; and the falling edge acquisition unit is used for determining a back electromotive force position detection signal of the half-bridge driving brushless direct current motor according to the rising edge delay time of the three-phase filtering position detection signal. According to the invention, the commutation reliability of the brushless direct current motor during the Hall fault can be greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of potential detection, in particular to a half-bridge driving brushless DC motor back electromotive force position detection system. BACKGROUND

[0002] The position sensorless control does not need a special position sensor control, has high reliability, low cost and other advantages, and is widely used in brushless DC motor driving control. The position sensorless control generally uses winding back electromotive force to detect the rotor commutation angle position. The position sensorless control mainly includes a back electromotive force detection method and a line back electromotive force method. The back electromotive force detection method needs a large number of operations to estimate the deviation of the back electromotive force zero-crossing time from the ideal commutation time.

[0003] The traditional line back electromotive force detection method has the problems of large commutation position detection deviation and large motor commutation pulse due to the high proportion of winding current resistance voltage drop in the terminal voltage at low speed, and the small signal-to-noise ratio of the back electromotive force signal in the winding terminal voltage at low speed, and the existence of false pulse phenomenon of the position detection square wave signal edge.

[0004] Therefore, there is an urgent need for a half-bridge driving brushless DC motor back electromotive force position detection system to solve the above technical problems. SUMMARY

[0005] The present application provides a half-bridge driving brushless DC motor back electromotive force position detection system, which can effectively improve the speed adaptation range and potential position detection precision of the motor. The technical scheme is as follows:

[0006] On the one hand, a half-bridge driving brushless DC motor back electromotive force position detection system is provided, which comprises a line voltage comparison unit, a digital filter unit and a falling edge acquisition unit connected in sequence, wherein:

[0007] The line voltage comparison unit comprises a voltage division module and a hysteresis comparison module, and the line voltage comparison unit is electrically connected with the motor three-phase winding. The line voltage comparison unit is used for comparing the terminal voltages of any two phases of the motor three-phase winding to obtain a three-phase initial position detection signal;

[0008] The digital filter unit comprises a filter time calculation module and a digital filter generation module, and the digital filter unit is used for performing edge filtering processing on the three-phase initial position detection signal according to the filter time to obtain a three-phase filtered position detection signal;

[0009] The falling edge acquisition unit comprises a rising edge delay time calculation module and a falling edge construction module, and the falling edge acquisition unit is used for determining a half-bridge driving brushless DC motor back electromotive force position detection signal according to the rising edge delay time of the three-phase filtered position detection signal.

[0010] In another aspect, a method for using a half-bridge driven brushless DC motor back electromotive force position detection system is provided, the method comprising:

[0011] The line voltage comparison unit compares the terminal voltages of the three-phase windings of the motor to obtain three-phase initial position detection signals;

[0012] The digital filter unit performs edge filtering on the three-phase initial position detection signals to obtain three-phase filtered position detection signals;

[0013] The falling edge acquisition unit calculates the rising edge delay time of the three-phase filtered position detection signals to determine the half-bridge driven brushless DC motor back electromotive force position detection signal.

[0014] The technical solution provided by the present application can bring the following advantages: first, the line voltage comparison unit performs low-pass filtering on the terminal voltages of the three-phase windings of the motor, and compares the three-phase terminal voltages in a hysteresis loop to obtain three-phase initial position detection signals. Then, the digital filter unit performs edge filtering on the three-phase initial position detection signals to eliminate edge false pulses and obtain three-phase filtered position detection signals. Finally, the falling edge acquisition unit calculates the falling edge of the output position detection signal using the rising edge delay of 180 degrees of the filtered three-phase digital pulse signal to ultimately obtain the half-bridge driven brushless DC motor back electromotive force position detection signal, which can replace the brushless DC motor Hall device for commutation position detection and speed calculation at medium and high speed stages. This system can effectively reduce false outputs caused by zero-crossing noise and electrical noise, and has the advantages of simple calculation and high accuracy of commutation position acquisition. BRIEF DESCRIPTION OF DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and those skilled in the art can obtain other drawings according to these drawings without creative labor.

[0016] Figure 1 is a structural block diagram of a half-bridge driven brushless DC motor back electromotive force position detection system provided by an embodiment of the present application;

[0017] Figure 2 is a structural block diagram of a line voltage comparison unit provided by an embodiment of the present application;

[0018] Figure 3 is a flowchart of a method for using a half-bridge driven brushless DC motor back electromotive force position detection system provided by an embodiment of the present application;

[0019] Figure 4 is a digital filter unit structure block diagram provided by an embodiment of the present application;

[0020] Figure 5 is a falling edge acquisition unit structure block diagram provided by an embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0022] As described above, the traditional line back electromotive force detection method has the problems of large commutation position detection deviation and large pulsation of motor commutation due to the small back electromotive force at low speed, the high proportion of winding current resistance voltage drop in terminal voltage, and the like.

[0023] Based on this, the present application provides a half-bridge driven brushless DC motor back electromotive force position detection system to replace the brushless DC motor Hall signal in situ to obtain high-precision potential position.

[0024] The specific implementation of the above concept will be described below.

[0025] Please refer to Figure 1 The half-bridge driven brushless DC motor back electromotive force position detection system provided by the embodiments of the present application comprises a line voltage comparison unit, a digital filter unit and a falling edge acquisition unit which are electrically connected in sequence, wherein:

[0026] The line voltage comparison unit comprises a voltage division module and a hysteresis comparison module, and is electrically connected with a motor three-phase winding.

[0027] The digital filter unit comprises a filter time calculation module and a digital filter generation module, and is used for performing edge filtering processing on the three-phase initial position detection signal according to the filter time to obtain a three-phase filtered position detection signal.

[0028] The falling edge acquisition unit comprises a rising edge delay time calculation module and a falling edge construction module, and is used for determining a half-bridge driven brushless DC motor back electromotive force position detection signal according to the rising edge delay time of the three-phase filtered position detection signal.

[0029] As Figure 2As shown, in the embodiment of the present invention, the voltage divider module includes a voltage divider resistor R a1 、R a2 、R b1 、R b2 、R c1 and R c2 , and filter capacitor C a 、C b and C c ,in:

[0030] Resistor R a1 The first end is electrically connected to the winding A, the resistor R a1 The second end of the resistor R a2 The first end is electrically connected to the resistor R a2 The second end of the resistor R a2 With capacitor C a Connected in parallel, the resistor R a1 and the resistor R a2 The connection point leads to the voltage divider output V a ;

[0031] Resistor R b1 The first end is electrically connected to the winding B, the resistor R b1 The second end of the resistor R b2 The first end is electrically connected to the resistor R b2 The second end of the resistor R b2 With capacitor C b Connected in parallel, the resistor R b1 and the resistor R b2 The connection point leads to the voltage divider output V b ;

[0032] Resistor R c1 The first end is electrically connected to the winding C, the resistor R c1 The second end of the resistor R c2 The first end is electrically connected to the resistor R c2 The second end of the resistor R c2 With capacitor C b Connected in parallel, the resistor R c1 and the resistor R c2 The connection point leads to the voltage divider output V c .

[0033] Furthermore, the maximum voltage U at the winding x terminal is max , voltage comparator input maximum voltage V max , the voltage divider resistor Rx1 and the voltage divider resistor Rx2 need to satisfy the following relationship:

[0034]

[0035] In the formula, x is the winding and the winding corresponding to the voltage divider resistance serial number, x=a, b, c; R x2 The selection of C x should ensure that the phase lag value of the low-pass filter formed by it at the maximum application frequency is less than 10 degrees.

[0036] In the embodiment of the application, the hysteresis comparison module comprises voltage comparators U a , U b , U c , hysteresis feedback resistors R a3 , R b3 , R c3 , pull-up resistors R a4 , R b4 , R c4 and output resistors R a5 , R b5 , R c5 , wherein:

[0037] The positive input end of the voltage comparator U a is electrically connected with the voltage division output V c , and the negative input end of the voltage comparator U a is electrically connected with the voltage division output V a .

[0038] The positive input end of the voltage comparator U b is electrically connected with the voltage division output V a , and the negative input end of the voltage comparator U b is electrically connected with the voltage division output V b .

[0039] The positive input end of the voltage comparator U c is electrically connected with the voltage division output V b , and the positive input end of the voltage comparator U c is electrically connected with the voltage division output V c .

[0040] The first end of the resistor R a3 is electrically connected with the positive input end of the U a , the first end of the resistor R a4 is electrically connected with the pull-up voltage V2, the second end of the resistor R a3 is electrically connected with the second end of the resistor R a4 , the first end of the resistor R a5 is electrically connected with the output end of the U a , and the second end of the resistor R a5 is electrically connected with the second end of the resistor R a4 , so as to obtain an initial position detection signal A.

[0041] The first end of the resistor Rb3 The first end and U b The positive input terminal is electrically connected to the resistor R b4 The first end of the resistor R is electrically connected to the pull-up voltage V2. b3 The second end of the resistor R b4 The second end of the resistor R b5 The first end and U b Output terminal electrical connection, resistor R b5 The second end of the resistor R b4 to obtain an initial position detection signal B;

[0042] Resistor R c3 The first end and U c The positive input terminal is electrically connected to the resistor R c4 The first end of the resistor R is electrically connected to the pull-up voltage V2. c3 The second end of the resistor R c4 The second end of the resistor R c5 The first end and U c Output terminal electrical connection, resistor R c5 The second end of the resistor R c4 to obtain an initial position detection signal C.

[0043] Furthermore, R x3 The resistance value needs to meet: 100R x2 <R x3 <500R x2 .

[0044] R x4 、R x5 Need to meet:

[0045]

[0046] Where V N Negative power supply voltage for the comparator.

[0047] Please refer to Figure 3 An embodiment of the present invention provides a method for using a half-bridge driven brushless DC motor back-electromotive force position detection system, the method comprising:

[0048] Step 300: using the line voltage comparison unit to compare the voltages at any two phase terminals of the three-phase winding of the motor to obtain a three-phase initial position detection signal;

[0049] Step 302: Using the digital filtering unit to perform edge filtering on the three-phase initial position detection signal to obtain a three-phase filtered position detection signal;

[0050] Step 304, calculating the falling edge delay time of the three-phase filtered position detection signal by using the falling edge acquisition unit, and determining the back electromotive force position detection signal of the half-bridge driven brushless direct current motor.

[0051] For step 302, performing edge filtering processing on the three-phase initial position detection signal by using the digital filtering unit to obtain the three-phase filtered position detection signal.

[0052] In the embodiment of the application, as shown in Figure 4 The three-phase filtered position detection signal is obtained by the following method: calculating the filtering time according to the motor speed by using the filtering time calculation module; and performing edge filtering processing on the three-phase initial position detection signal according to the filtering time by using the digital filtering generation module to obtain the three-phase filtered position detection signal.

[0053] Specifically, the filtering time T1 is calculated by the following formula:

[0054]

[0055] Wherein, N p is the number of motor pole pairs; C f is the filtering coefficient; V s is the motor speed.

[0056] Further, if the initial position detection signal corresponding to the target winding is opposite to the filtered position detection signal corresponding to the target winding within continuous T1 time, the filtered position detection signal is processed in reverse; otherwise, the filtered position detection signal remains unchanged.

[0057] Specifically, if the initial position detection signal A is opposite to the filtered position detection signal A within continuous T1 time, the filtered position detection signal A is processed in reverse; otherwise, the filtered position detection signal A remains unchanged.

[0058] If the initial position detection signal B is opposite to the filtered position detection signal B within continuous T1 time, the filtered position detection signal B is processed in reverse; otherwise, the filtered position detection signal B remains unchanged.

[0059] If the initial position detection signal C is opposite to the filtered position detection signal C within continuous T1 time, the filtered position detection signal C is processed in reverse; otherwise, the filtered position detection signal C remains unchanged.

[0060] For step 304, calculating the falling edge delay time of the three-phase filtered position detection signal by using the falling edge acquisition unit, and determining the back electromotive force position detection signal of the half-bridge driven brushless direct current motor.

[0061] In the embodiment of the application, as shown in Figure 5As shown, the back EMF position detection signal of the half-bridge driven brushless DC motor is obtained by the following method: the rising edge delay time calculation module calculates the rising edge delay time according to the motor speed; and the falling edge construction module determines the back EMF position detection signal of the half-bridge driven brushless DC motor according to the rising edge delay time.

[0062] Specifically, the rising edge delay time T2 is calculated by the following formula:

[0063]

[0064] Wherein, N p is the number of motor pole pairs; V s is the motor speed.

[0065] Further, if the falling edge construction module detects the rising edge of the filtered position detection signal of the target winding, the output position detection signal of the target winding is set to high level, and a timer is started to count, and when the timer counts T2 time, the output position detection signal is set to low level, and the back EMF position detection signal of the half-bridge driven brushless DC motor is obtained.

[0066] Specifically, the falling edge construction module detects the rising edge of the filtered position detection signal A, and the output position detection signal A is set to high level, and a timer is started to count, and when the timer counts T2 time, the output position detection signal A is set to low level, and the cycle is repeated.

[0067] The falling edge construction module detects the rising edge of the filtered position detection signal B, and the output position detection signal B is set to high level, and a timer is started to count, and when the timer counts T2 time, the output position detection signal B is set to low level, and the cycle is repeated.

[0068] The falling edge construction module detects the rising edge of the filtered position detection signal C, and the output position detection signal C is set to high level, and a timer is started to count, and when the timer counts T2 time, the output position detection signal C is set to low level, and the cycle is repeated.

[0069] The above system can obtain the commutation position by using the winding back EMF of the half-bridge driven brushless DC motor, and greatly improves the commutation reliability of the brushless DC motor when the Hall fails.

[0070] For the convenience of description, the above system or device is described as various modules or units in function. Of course, the functions of each unit can be implemented in the same or multiple software and / or hardware in the implementation of the present application.

[0071] Those skilled in the art can clearly understand the application by the description of the above embodiments. The technical solutions of the application can be implemented by means of software and necessary universal hardware platforms. Based on such an understanding, the technical solutions of the application can be embodied in the form of a software product, which can be stored in a storage medium, such as a ROM / RAM, a magnetic disk, or an optical disk, and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in various embodiments or some parts of the embodiments of the application.

[0072] Finally, it should be noted that the terms such as first, second, third, and fourth, etc. are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "including a" does not exclude the presence of other identical elements in the process, method, article or device including the element.

[0073] The above description is only the preferred embodiments of the application, and it should be pointed out that those skilled in the art can make some improvements and refinements without departing from the principles of the application, and these improvements and refinements should also be regarded as the protection scope of the application.

Claims

1. A half-bridge drive brushless DC motor back-EMF position detection system, characterized by, The system comprises a line voltage comparison unit, a digital filter unit and a falling edge acquisition unit connected in sequence, wherein: The line voltage comparison unit comprises a voltage division module and a hysteresis comparison module, and is electrically connected with the three-phase winding of the motor, and is used for comparing the voltages at the ends of the three-phase winding two by two to obtain three-phase initial position detection signals; The digital filter unit comprises a filter time calculation module and a digital filter generation module, and is used for performing edge filtering processing on the three-phase initial position detection signals according to the filter time to obtain three-phase filtered position detection signals; The falling edge acquisition unit comprises a rising edge delay time calculation module and a falling edge construction module, and is used for determining the back electromotive force position detection signal of the half-bridge driven brushless DC motor according to the rising edge delay time of the three-phase filtered position detection signals.

2. The system of claim 1, wherein, The voltage division module comprises voltage division resistors R a1 , R a2 , R b1 , R b2 , R c1 , and R c2 , and filter capacitors C a , C b , and C c , wherein: Resistor R a1 The first end is electrically connected to the winding A, the resistor R a1 The second end of the resistor R a2 The first end is electrically connected to the resistor R a2 The second end of the resistor R a2 Connected in parallel with the capacitor Ca, the resistor R a1 and the resistor R a2 The connection point leads to the voltage divider output V a ; a first end of the resistor R b1 is electrically connected with the winding B, a second end of the resistor R b1 is electrically connected with a first end of the resistor R b2 , a second end of the resistor R b2 is grounded, the resistor R b2 is connected in parallel with the capacitor C b , the resistor R b1 and the resistor R b2 are connected in series, and a connection point of the resistor R b1 and the resistor R b2 leads out a voltage division output V b ; Resistor R c1 The first end is electrically connected to the winding C, the resistor R c1 The second end of the resistor R c2 The first end is electrically connected to the resistor R c2 The second end of the resistor R c2 With capacitor C b Connected in parallel, the resistor R c1 and the resistor R c2 The connection point leads to the voltage divider output V c .

3. The system of claim 1, wherein, The hysteresis comparison module comprises a voltage comparator U a , U b , U c , a hysteresis feedback resistor R a3 , R b3 , R c3 , a pull-up resistor R a4 , R b4 , R c4 , and an output resistor R a5 , R b5 , R c5 , wherein: The positive input of the voltage comparator U a is connected to the voltage divider output V c The negative input of the voltage comparator U a is connected to the voltage divider output V a . The positive input of the voltage comparator U b is connected to the voltage divider output V a The negative input of the voltage comparator U b is connected to the voltage divider output V b . The positive input of the voltage comparator U c is electrically connected to the divided output V b The positive input of the voltage comparator U c is electrically connected to the divided output V c The positive input of the voltage comparator U Resistor R a3 The first end and U a The positive input terminal is electrically connected to the resistor R a4 The first end of the resistor R is electrically connected to the pull-up voltage V2. a3 The second end of the resistor R a4 The second end of the resistor R a5 The first end and U a Output terminal electrical connection, resistor R a5 The second end of the resistor R a4 to obtain an initial position detection signal A; The first end of the resistor R b3 is electrically connected with the positive input end of the U b , the first end of the resistor R b4 is electrically connected with the pull-up voltage V2, the second end of the resistor R b3 is electrically connected with the first end of the resistor R b4 , the second end of the resistor R b5 is electrically connected with the negative input end of the U b , and the second end of the resistor R b5 is electrically connected with the output end of the U b4 , so as to obtain the initial position detection signal B. The first end of the resistor R c3 is electrically connected with the positive input end of the U c , the first end of the resistor R c4 is electrically connected with the pull-up voltage V2, the second end of the resistor R c3 is electrically connected with the resistor R c4 , the second end of the resistor R c5 is electrically connected with the U c output end, the second end of the resistor R c5 is electrically connected with the resistor R c4 , and an initial position detection signal C is obtained.

4. A method of using a half-bridge drive brushless DC motor back-EMF position detection system, characterized by, The method is applied to the system as claimed in claims 1-3, and comprises: comparing the voltages at the ends of the three-phase winding two by two by using the line voltage comparison unit to obtain three-phase initial position detection signals; performing edge filtering processing on the three-phase initial position detection signals by using the digital filter unit to obtain three-phase filtered position detection signals; calculating the rising edge delay time of the three-phase filtered position detection signals by using the falling edge acquisition unit to determine the back electromotive force position detection signal of the half-bridge driven brushless DC motor.

5. The method of claim 4, wherein, The step of performing edge filtering processing on the three-phase initial position detection signals by using the digital filter unit to obtain three-phase filtered position detection signals comprises: calculating the filter time according to the motor speed by using the filter time calculation module; performing edge filtering processing on the three-phase initial position detection signals according to the filter time by using the digital filter generation module to obtain three-phase filtered position detection signals.

6. The method of claim 5, wherein, The filter time T1 is calculated by the following formula: where N p is the number of motor pole pairs; C f is the filter coefficient; V s is the motor speed.

7. The method of claim 6, wherein, The step of performing edge filtering processing on the three-phase initial position detection signals to obtain three-phase filtered position detection signals comprises: if the initial position detection signal corresponding to the target winding is opposite to the filtered position detection signal corresponding to the target winding within continuous T1 time, performing reverse processing on the filtered position detection signal; otherwise, keeping the filtered position detection signal unchanged.

8. The method of claim 4, wherein, The step of calculating the rising edge delay time of the three-phase filtered position detection signals by using the falling edge acquisition unit to determine the back electromotive force position detection signal of the half-bridge driven brushless DC motor comprises: calculating the rising edge delay time according to the motor speed by using the rising edge delay time calculation module; determining the back electromotive force position detection signal of the half-bridge driven brushless DC motor according to the rising edge delay time by using the falling edge construction module.

9. The method of claim 8, wherein, The rising edge delay time T2 is calculated by the following formula: where N p is the number of motor pole pairs; V s is the motor speed.

10. The method of claim 9, wherein, The step of determining the back electromotive force position detection signal of the half-bridge driven brushless DC motor according to the rising edge delay time comprises: If the falling edge configuration module detects the rising edge of the filtered position detection signal of the target winding, the output position detection signal of the target winding is set to high level, and a timer is started to count, and when the timer counts T2 time, the output position detection signal is set to low level, to obtain the back electromotive force position detection signal of the half-bridge driven brushless direct current motor.

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