CN114688953A - Circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signal - Google Patents

Circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signal Download PDF

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CN114688953A
CN114688953A CN202011616310.8A CN202011616310A CN114688953A CN 114688953 A CN114688953 A CN 114688953A CN 202011616310 A CN202011616310 A CN 202011616310A CN 114688953 A CN114688953 A CN 114688953A
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voltage
motor
phase
comparator
mcu
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陈宇
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CRM ICBG Wuxi Co Ltd
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CRM ICBG Wuxi Co Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B7/00—Measuring arrangements characterised by the use of electric or magnetic techniques
    • G01B7/003—Measuring arrangements characterised by the use of electric or magnetic techniques for measuring position, not involving coordinate determination

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Abstract

The invention relates to a circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signal, which comprises a comparator, wherein the positive input end of the comparator is respectively connected with motor A phase voltage, motor B phase voltage and motor C phase voltage, and the negative input end of the comparator is connected with an inverter bus voltage; under the condition that any two phases of the motor A phase voltage, the motor B phase voltage and the motor C phase voltage are conducted, the counter electromotive force signal of the current suspension phase is obtained by detecting the output signal of one path of comparator, and the rotor phase change is realized. By adopting the circuit structure for realizing the position detection of the non-inductive BLDC rotor based on the MCU detection commutation signal, only one comparator is needed, and the hardware cost can be saved. The selection area of the MCU is enlarged, and the MCU with low cost is selected, so that a motor drive special MCU integrating a 3-path comparator is not required to be selected. The invention only needs one IO port to detect the commutation signal, saves IO resources and simultaneously improves the utilization rate of the IO port.

Description

Circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signal
Technical Field
The invention relates to the field of brushless direct current motors, in particular to the field of rotor position detection, and specifically relates to a circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signals.
Background
In the existing scheme for detecting the counter electromotive force zero crossing, a three-way comparator is adopted to respectively judge the zero crossing point of each phase, and the phase change time is judged by detecting the counter electromotive force zero crossing point of a non-conducting phase (floating phase). There are two main approaches to using three-way comparators. One approach is to have the MCU external to the comparator chip, which adds additional hardware cost. In another method, an MCU integrated with a three-way comparator or a special MCU for motor driving is selected. The mainstream MCU is mostly integrated with 1 path or 2 paths of comparators, the MCU of the integrated 3 paths of comparators is less and is mostly a special MCU for motor drive, the cost is higher and the selectable range is very small.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a circuit structure for realizing the non-inductive BLDC rotor position detection based on the MCU detection commutation signal, which has the advantages of simple structure, high utilization rate and wider application range.
In order to achieve the above object, the circuit structure for detecting the commutation signal based on the MCU to achieve the non-inductive BLDC rotor position detection of the present invention is as follows:
the circuit structure for realizing the position detection of the non-inductive BLDC rotor based on the MCU detection commutation signal is mainly characterized in that the circuit structure comprises a comparator, wherein the positive input end of the comparator is respectively connected with the phase voltage of a motor A, the phase voltage of a motor B and the phase voltage of a motor C, and the negative input end of the comparator is connected with the bus voltage of an inverter; the one-way comparator obtains an output signal by comparing the positive input voltage with the negative input voltage;
under the condition that any two phases of the motor A phase voltage, the motor B phase voltage and the motor C phase voltage are conducted, the counter electromotive force signal of the current suspension phase is obtained by detecting the output signal of the one-way comparator, and the rotor phase change is realized.
Preferably, the motor a-phase voltage, the motor B-phase voltage and the motor C-phase voltage are connected with the positive input end of the one path of comparator through the same voltage dividing circuit.
Preferably, the voltage dividing circuit includes a first voltage dividing circuit, a second voltage dividing circuit and a third voltage dividing circuit, the first voltage dividing circuit, the second voltage dividing circuit and the third voltage dividing circuit are the same and each includes a plurality of resistors and a capacitor,
the motor A-phase voltage is connected with the positive input end of a comparator through the first voltage division circuit, one polar plate of a capacitor in the first voltage division circuit is grounded, the other polar plate is connected with the motor A-phase voltage through one resistor,
the motor B phase voltage is connected with the positive input end of a comparator through the second voltage division circuit, one polar plate of a capacitor in the second voltage division circuit is grounded, the other polar plate is connected with the motor B phase voltage through one resistor,
the motor C-phase voltage is connected with the positive input end of a comparator through the third voltage division circuit, one polar plate of a capacitor in the third voltage division circuit is grounded, and the other polar plate is connected with the motor C-phase voltage through one resistor.
Preferably, the capacitance of the capacitor of the voltage division circuit is in nF level, and the resistance value of the resistor is at least 10 times smaller than the input impedance of the comparator.
Preferably, the inverter bus voltage is connected to a negative input terminal of the comparator via a fourth voltage dividing circuit.
Preferably, the voltage value of the inverter bus voltage is determined based on a motor rated voltage of the non-inductive BLDC.
Preferably, when any two of the phase voltage of the motor a, the phase voltage of the motor B, and the phase voltage of the motor C are conducted, the positive input voltage and the negative input voltage of one path of the comparator satisfy the following formula:
V－＝Vbus/2；
V+＝(Ua+Ub+Uc)/3＝Vbus/2+Esuspended phase/3；
Wherein Vbus is the bus voltage of the driver, Ua, Ub and Uc are the voltages to ground of the phase voltage A of the motor, the phase voltage B of the motor and the phase voltage C of the motor respectively, and ESuspended phaseFor the current levitated counter electromotive force, V+A positive input voltage of V－The negative input voltage.
Preferably, under the condition that any two phases of the motor a-phase voltage, the motor B-phase voltage and the motor C-phase voltage are conducted, when the current suspension counter electromotive force is greater than 0, the positive input voltage is greater than the negative input voltage, and the output of one comparator is 1; when the current suspension counter electromotive force is equal to 0, the positive input voltage is equal to the negative input voltage, and an output signal of one comparator is inverted; when the current suspension counter electromotive force is smaller than 0, the positive input voltage is smaller than the negative input voltage, and the output of one comparator is 0.
Preferably, the output end of the circuit structure is directly connected with the MCU, and the circuit structure realizes signal transmission with the MCU through 1 IO port of the MCU. .
Preferably, the output end of the circuit structure is connected with the MCU through an RC network, and the circuit structure is connected with the RC network and then realizes signal transmission with the MCU through 1 IO port of the MCU.
By adopting the circuit structure for realizing the position detection of the non-inductive BLDC rotor based on the MCU detection commutation signal, only one comparator is needed, and the hardware cost can be saved. General purpose MCUs integrated with one path of comparator are more in the market, so that the selection range of the MCU can be expanded, and MCUs with low cost are selected without selecting a motor drive special MCU integrated with a 3-path comparator. The invention only needs one IO port to detect the commutation signal. IO resources can be saved, and meanwhile, the utilization rate of an IO port is improved.
Drawings
Fig. 1 is a schematic diagram of a non-inductive position detection circuit in an embodiment.
Fig. 2 is a diagram of a mathematical model of a three-phase coil of a motor in an embodiment.
Fig. 3 is a schematic diagram of a circuit structure for implementing non-inductive BLDC rotor position detection based on MCU detection commutation signal in an embodiment.
FIG. 4 is a diagram illustrating a circuit configuration for implementing non-inductive BLDC rotor position detection based on MCU detection commutation signals in an embodiment.
Fig. 5 is a schematic diagram of input voltages and output voltages of the three-way comparator in an H _ ON _ L _ ON state according to an embodiment.
Fig. 6 is a schematic diagram of an input voltage of one comparator and an output voltage of the comparator in an H _ ON _ L _ ON state according to an embodiment.
Fig. 7 is a schematic diagram showing comparison between an output signal of one comparator in an embodiment and an output signal of a three-way comparator in the prior art.
FIG. 8 is a schematic diagram of the input voltage and the output voltage of the three-way comparator in the H _ PWM _ L _ ON state according to an embodiment.
Fig. 9 is a schematic diagram of an input voltage of one comparator and an output voltage of the comparator in an H _ PWM _ L _ ON state according to an embodiment.
Fig. 10 is a schematic diagram showing a comparison between an output signal of one comparator in an embodiment and an output signal of a three-way comparator in the prior art.
Detailed Description
In order to more clearly describe the technical contents of the present invention, the following further description is given in conjunction with specific embodiments.
FIG. 1 shows a typical non-sensing position detection circuit.
In the technical scheme, Ua, Ub and Uc are voltages of a three-phase terminal to the ground respectively. And positive input V + of the three-way comparator is ABC three-phase end-to-ground voltage respectively. The input negative electrodes V-of the three-way comparator are (Va + Vb + Vc)/3.
Fig. 2 shows a mathematical model of a three-phase coil of an electric machine.
In the figure, Ra, Rb and Rc are three-phase resistances, Ra, Rb, Rc and R, La, Lb and Lc are three-phase inductances, La, Lb, Lc and L, Ea, Eb and Ec are three-phase counter electromotive forces, and Vn is a coil neutral point voltage.
Assume that the phase a high side and the phase B low side are conductive at a certain time, and the phase C is a non-conductive phase, i.e., a floating phase. Then Ua-Vbus and Ub-Uce. Wherein Vbus is the bus voltage of the driver, and Uce is the conduction voltage drop of the power tube. Current flows from phase a into phase B, so that Ib ═ Ia is obtained. Phase C is suspended so that Ic is 0.
Ua＝Ra×Ia+La×dIa/dt+Ea+Vn； (1－1)
Ub＝Rb×Ib+Lb×dIb/dt+Eb+Vn； (1－2)
Uc＝Rc×Ic+Lc×dIc/dt+Ec+Vn； (1－3)
Therefore, Ua + Ub ═ R × (Ia + Ib) + L × (dIa/dt + dIb/dt) + (Ea + Eb) +2 × Vn ═ Vbus-Uce + Uce. Since Ib is-Ia and then Eb is-Ea.
Then Ua + Ub is 2 × Vn is Vbus, so Vn is Vbus/2, and since Ic is 0, Uc is Ec + Vn, so (Ua + Ub)/3 ═ Vn + Ec/3 is Vbus/2+ Ec/3.
In summary, when the AB phase is conducted, the input voltages of the comparators in the suspended phase C are respectively
V+＝Vbus/2+Ec
V－＝Vbus/2+Ec/3
Similarly, when the phase a and the phase B are the suspension phase, the voltages input by the positive and negative electrodes of the comparator are respectively:
when phase B is in suspension, V+＝Vbus/2+Eb；V－＝Vbus/2+Eb/3；
When phase A is in suspension, V+＝Vbus/2+Ea；V－＝Vbus/2+Ea/3；
When the counter electromotive force of the suspension phase is delayed for 60 degrees of electrical angle time after zero crossing, the motor can change the phase. Therefore, the phase can be switched by detecting the zero crossing point of the suspended counter electromotive force.
Taking the detection of the C-phase levitated back electromotive force as an example, when the driving method of H _ ON _ L _ ON is adopted,
when Ec is reached>At 0, V+＝Vbus/2+Ec；V－＝Vbus/2+Ec/3；V+>V－(ii) a Comparator output 1;
when Ec is 0, V+＝Vbus/2；V－＝Vbus/2；V+＝V－(ii) a Turning over the comparator;
when Ec<At 0, V+＝Vbus/2+Ec；V－＝Vbus/2＝Ec/3；V+<V－(ii) a Comparator output 0;
when the H _ PWM _ L _ ON driving mode is adopted, the terminal voltage jumps in the PWM OFF state due to PWM, and the comparator is subjected to high-low level inversion due to the jump, so that the judgment of a zero crossing point is interfered. The detection of the high and low levels output by the comparator is usually performed in the PWM ON period, so that the incorrect zero-crossing signal in the PWM OFF period can be avoided. Therefore, the zero crossing point can be known by detecting the high and low levels output by the floating comparator, and the correct phase change is realized.
The commonly used three comparators output three high-low level signals to prompt the phase change time of the rotor, so 3 IO ports of the MCU are consumed, and IO resources are occupied by comparison. And each path of IO port can be detected only when the phase is suspended, so that the utilization rate is not high. Because only one comparator is used and only one signal is output to prompt the phase change time of the rotor, only 1 IO port of the MCU is needed to be consumed, IO resources can be saved, the utilization rate of the IO port is improved, and the problem of large number of IO ports needed by detecting phase change is solved.
The circuit structure for realizing the position detection of the non-inductive BLDC rotor based on the MCU detection commutation signal comprises a comparator, wherein the positive input end of the comparator is respectively connected with the phase voltage of a motor A, the phase voltage of a motor B and the phase voltage of a motor C, and the negative input end of the comparator is connected with the bus voltage of an inverter; the comparator obtains an output signal by comparing the anode input voltage with the cathode input voltage;
under the condition that any two phases of the motor A phase voltage, the motor B phase voltage and the motor C phase voltage are conducted, the counter electromotive force signal of the current suspension phase is obtained by detecting the output signal of one path of comparator, and the rotor phase change is realized.
The motor A phase voltage, the motor B phase voltage and the motor C phase voltage are connected with the positive input end of the comparator through the voltage division circuit.
The voltage division circuit comprises a first voltage division circuit, a second voltage division circuit and a third voltage division circuit, the first voltage division circuit, the second voltage division circuit and the third voltage division circuit are the same and respectively comprise a plurality of resistors and a capacitor,
the motor A-phase voltage is connected with the positive input end of a comparator through the first voltage division circuit, one polar plate of a capacitor in the first voltage division circuit is grounded, the other polar plate is connected with the motor A-phase voltage through one resistor,
the motor B phase voltage is connected with the positive input end of a comparator through the second voltage division circuit, one polar plate of a capacitor in the second voltage division circuit is grounded, the other polar plate is connected with the motor B phase voltage through one resistor,
the motor C-phase voltage is connected with the positive input end of a comparator through the third voltage division circuit, one polar plate of a capacitor in the third voltage division circuit is grounded, and the other polar plate is connected with the motor C-phase voltage through one resistor.
The capacitance of the voltage divider circuit is in the order of nF, and the resistance of the resistor is at least 10 times smaller than the input impedance of the comparator.
The inverter bus voltage is connected with the negative input end of the comparator through a fourth voltage dividing circuit, one polar plate of a capacitor in the fourth voltage dividing circuit is grounded, the other polar plate is connected with the inverter bus voltage through one resistor, and the negative input end is grounded through the other resistor.
The voltage value of the inverter bus voltage is determined based on the motor rated voltage of the non-inductive BLDC. Preferably, when any two phases of the motor a-phase voltage, the motor B-phase voltage and the motor C-phase voltage are conducted, the positive input voltage V of one path of comparator is+And a negative input voltage V－The following formula is satisfied:
V－＝Vbus/2；
V+＝(Ua+Ub+Uc)/3＝Vbus/2+Esuspended phase/3；
Wherein Vbus is the bus voltage of the driver, Ua, Ub and Uc are the voltages to ground of the phase voltage A of the motor, the phase voltage B of the motor and the phase voltage C of the motor respectively, and ESuspended phaseIs the current floating counter electromotive force.
Preferably, under the condition that any two phases of the motor A phase voltage, the motor B phase voltage and the motor C phase voltage are conducted, when the current suspension opposite electromotive force is greater than 0, the positive input voltage is greater than the negative input voltage, and the output of one comparator is 1; when the current suspension counter electromotive force is equal to 0, the positive input voltage is equal to the negative input voltage, and the output signal of one comparator is inverted; when the current suspension counter electromotive force is smaller than 0, the anode input voltage is smaller than the cathode input voltage, and the output of one comparator is 0.
Preferably, the number of the IO ports of the MCU required by the circuit structure is 1.
In the specific implementation manner of the invention, the problems that the existing non-inductive BLDC position detection circuit needs a large number of comparators and a large number of IO ports for detecting commutation signals are solved. The non-inductive BLDC has no hall sensor, and therefore must be position-detected from the three-phase terminal-to-ground voltage. The existing position detection circuit needs three comparators, so an external hardware comparator (such as LM339) is usually adopted, or a motor drive special MCU integrating 3 comparators is selected.
Aiming at the defect that the number of comparators is large, the invention can detect the phase change signals of three phases only by one comparator, so that an external hardware comparator is not needed, or an MCU integrating one comparator is selected. And a low-cost general MCU integrating a 1-path comparator is selected, so that the cost can be reduced, and the selection range of the MCU is expanded.
Fig. 3 shows a schematic diagram. Fig. 4 is a schematic diagram of a circuit structure for detecting the position of the non-inductive BLDC rotor based on the MCU for detecting the commutation signal according to the present invention.
As shown in fig. 4, the U-phase voltage, the V-phase voltage and the W-phase voltage of the motor are connected to a positive input terminal of a comparator through the same RC structure, the RC structure includes a plurality of resistors and capacitors, the capacitors are connected in parallel to one of the resistors, one end of each capacitor is grounded, and the other end of each capacitor is connected to the U-phase voltage, the V-phase voltage and the W-phase voltage of the motor through the resistors and is connected to a positive input terminal of a comparator through the resistors. The capacitance under the UVW three-phase voltage division network is generally in the nF level every time 1pcs is connected, and the parameters of the capacitance are the withstand voltage and the capacitance value, but not the quantity. The voltage of the capacitor is reduced and then is larger than the highest voltage value of the phase voltage after the voltage of the phase voltage is divided by the voltage dividing network. Increasing the capacitance is beneficial for making the waveform smoother and reducing glitches, but causes the detected back emf zero-crossings to lag behind. The zero crossing point detection timeliness requires that the capacitor is as small as possible even not connected with the capacitor, but the reduction of burrs requires that the capacitor is as large as possible, so that the two contradictory aspects are realized, and the compromise is about 1 nF.
The upper limit value of the resistance of the voltage division network to ground is related to the input impedance of the comparator. The input impedance of the comparator is generally in the megaohm level, the resistance of the invention is preferably 10 times smaller than the input impedance of the comparator, otherwise the voltage of the voltage division network is influenced by the input impedance of the comparator to generate deviation. The lower limit is related to the power in the form of a resistor that is not burdened with power exceeding the value of the resistor that is derated by the maximum tolerated power. The resistance value of a resistor connected with the phase voltage is related to the ratio of the phase voltage to the input voltage of the comparator, the resistance value of the resistor connected with the phase voltage is determined according to the ratio of the phase voltage to the input voltage of the comparator, the phase voltage is determined by the rated voltage of the motor, and the input voltage of the comparator is designated by a comparator data manual. After the resistance value is determined, whether a mode of connecting a plurality of resistors in series is adopted, the number of the resistors in series and the resistance value of each resistor are determined according to the withstand voltage and the power of the resistors.
The inverter bus voltage of the present invention depends on the rated voltage of the motor.
The output signal of the comparator of the invention is transmitted to the MCU, and the output end of the circuit structure is connected with the MCU through the RC network or directly connected with the MCU according to the actual situation.
The average (Ua + Ub + Uc)/3 of the three-phase to ground voltage Ua, Ub, Uc of the invention already contains commutation information of all three phases
When phase A is suspended, (Ua + Ub + Uc)/3 ═ Vbus/2+ Ea/3;
when B phase is suspended, (Ua + Ub + Uc)/3 ═ Vbus/2+ Eb/3;
when phase C is suspended, (Ua + Ub + Uc)/3 ═ Vbus/2+ Ec/3.
Therefore, when any two phases are conducted, (Ua + Ub + Uc)/3 is the back electromotive force signal of the non-conducted suspension phase. Therefore, the scheme compares (Ua + Ub + Uc)/3 with Vbus/2, and only needs a 1-way comparator. Since (Ua + Ub + Uc)/3 contains the commutation signal of the current floating phase, the output of the comparator is the counter potential zero crossing signal of the current floating phase. Only 1 IO port is required for detection.
Assuming that the current A phase high side and B phase low side are conducted, the C phase floats.
When in the ON mode of H ON L ON,
V+＝(Ua+Ub+Uc)/3＝Vbus/2+Ec/3；
V－＝Vbus/2；
when Ec is reached>At 0, V+>V－The comparator outputs 1;
when Ec is 0, V+＝V－The comparator is turned over;
when Ec is reached<At 0, V+<V－And the comparator outputs 0.
When in the ON mode of H _ PWM _ L _ ON, sampling is performed within the PWM ON period to avoid interference of the PWM OFF state with the zero-crossing signal.
Therefore, if the AB phase is turned on at this time, the detection output signal is the counter electromotive force signal for detecting the C phase of the floating phase. If the AC phase is conducted, the detection output signal is the detected back electromotive force signal of the suspension phase B phase. If the BC phase is conducted, the detection output signal is the counter electromotive force signal of the A phase of the detected suspension phase. And the MCU knows which two phases are currently conducted, so that the back electromotive force signal of which phase is currently reflected by the signal can be distinguished from the 1-path signal.
In summary, the method can use 1 way comparator and 1 IO port to detect all the zero-crossing signals of 3 phases.
As shown in fig. 5, it is a schematic diagram of the input voltage and the output voltage of the three-way comparator in the conventional scheme H _ ON _ L _ ON state. As shown in fig. 6, this is a schematic diagram of the input voltage of one comparator and the output voltage of the comparator in the H _ ON _ L _ ON state of the present scheme.
As shown in fig. 7, this is a schematic diagram comparing the output signal of the one-way comparator with the output signal of the three-way comparator in the present scheme, which is equivalent to synthesizing the original three-way signals into one way. Fig. 8 is a schematic diagram of the input voltage and the output voltage of the three-way comparator in the conventional H _ PWM _ L _ ON state.
As shown in fig. 9, this is a schematic diagram of the input voltage of one comparator and the output voltage of the comparator in the H _ PWM _ L _ ON state of the present scheme. As shown in fig. 10, this is a schematic diagram comparing the output signal of the one-way comparator in the present embodiment with the output signal of the three-way comparator in the present embodiment, which is equivalent to combining the original three-way signals into one path.
By adopting the circuit structure for realizing the position detection of the non-inductive BLDC rotor based on the MCU detection commutation signal, only one comparator is needed, and the hardware cost can be saved. The general MCU integrated with one path of comparator on the market is more, so that the selection range of the MCU can be enlarged, and some low-cost MCUs are selected without selecting a special motor-driven MCU integrated with 3 paths of comparators. The invention only needs one IO port to detect the commutation signal. IO resources can be saved, and meanwhile, the utilization rate of an IO port is improved.
In this specification, the invention has been described with reference to specific embodiments thereof. It will, however, be evident that various modifications and changes may be made thereto without departing from the broader spirit and scope of the invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than a restrictive sense.

Claims (10)

1. A circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection phase-change signals is characterized in that the circuit structure comprises a comparator, wherein the positive pole input end of the comparator is respectively connected with motor A phase voltage, motor B phase voltage and motor C phase voltage, and the negative pole input end of the comparator is connected with an inverter bus voltage; the comparator obtains an output signal by comparing the anode input voltage with the cathode input voltage;
under the condition that any two phases of the motor A phase voltage, the motor B phase voltage and the motor C phase voltage are conducted, the counter electromotive force signal of the current suspension phase is obtained by detecting the output signal of the one-way comparator, and the rotor phase change is realized.
2. The circuit structure for detecting the position of the non-inductive BLDC rotor based on the phase-change signal detected by the MCU of claim 1, wherein the motor A-phase voltage, the motor B-phase voltage and the motor C-phase voltage are connected with a positive input end of the comparator through a voltage division circuit.
3. The circuit structure for detecting a commutation signal based on an MCU of claim 2 to achieve non-inductive BLDC rotor position detection, wherein the voltage divider circuit comprises a first voltage divider circuit, a second voltage divider circuit, and a third voltage divider circuit, the first voltage divider circuit, the second voltage divider circuit, and the third voltage divider circuit are identical and each comprise a plurality of resistors and a capacitor,
the motor A phase voltage is connected with the positive input end of a comparator through the first voltage division circuit, one polar plate of a capacitor in the first voltage division circuit is grounded, the other polar plate is connected with the motor A phase voltage through one resistor,
the motor B phase voltage is connected with the positive input end of a comparator through the second voltage division circuit, one polar plate of a capacitor in the second voltage division circuit is grounded, the other polar plate is connected with the motor B phase voltage through one resistor,
the motor C-phase voltage is connected with the positive input end of a comparator through the third voltage division circuit, one polar plate of a capacitor in the third voltage division circuit is grounded, and the other polar plate is connected with the motor C-phase voltage through one resistor.
4. The circuit structure for detecting the rotor position of the non-inductive BLDC motor according to claim 3, wherein the capacitor of the voltage divider circuit has a capacitance of nF level, and the resistance of the resistor is at least 10 times smaller than the input impedance of the comparator.
5. The circuit structure for detecting the commutation signal based on the MCU of claim 1, wherein the inverter bus voltage is connected to the negative input terminal of the comparator via a fourth voltage divider.
6. The circuit structure for detecting rotor position of non-inductive BLDC based on MCU detected commutation signal of claim 1, wherein said voltage value of inverter bus voltage is determined based on motor rated voltage of said non-inductive BLDC.
7. The circuit structure for detecting the commutation signal based on the MCU of claim 1 to achieve the position detection of the non-inductive BLDC rotor, wherein when any two of the a-phase voltage, the B-phase voltage and the C-phase voltage of the motor are turned on, the positive input voltage and the negative input voltage of one comparator satisfy the following formula:
V－＝Vbus/2；
V+＝(Ua+Ub+Uc)/3＝Vbus/2+Esuspended phase/3；
Wherein Vbus is the bus voltage of the driver, Ua, Ub and Uc are the voltages to ground of the phase voltage A of the motor, the phase voltage B of the motor and the phase voltage C of the motor respectively, and ESuspended phaseFor the current levitated counter electromotive force, V+A positive input voltage of V－The negative input voltage.
8. The circuit structure for detecting the position of the non-inductive BLDC rotor based on the phase-change signal detected by the MCU of claim 7, wherein when any two phases of the motor A-phase voltage, the motor B-phase voltage and the motor C-phase voltage are conducted, and when the current suspension counter electromotive force is greater than 0, the positive input voltage is greater than the negative input voltage, and the output of one comparator is 1; when the current suspension counter electromotive force is equal to 0, the positive input voltage is equal to the negative input voltage, and an output signal of one comparator is inverted; when the current suspension counter electromotive force is smaller than 0, the positive input voltage is smaller than the negative input voltage, and the output of one comparator is 0.
9. The circuit structure for detecting the commutation signal based on the MCU to achieve the position detection of the non-inductive BLDC rotor according to claim 1, wherein an output end of the circuit structure is directly connected with the MCU, and the circuit structure realizes signal transmission with the MCU through 1 IO port of the MCU.
10. The circuit structure for detecting the commutation signal based on the MCU to realize the position detection of the non-inductive BLDC rotor according to claim 1, wherein an output end of the circuit structure is connected with the MCU through an RC network, and the circuit structure is connected with the RC network and then realizes signal transmission with the MCU through 1 IO port of the MCU.
CN202011616310.8A 2020-12-30 2020-12-30 Circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signal Pending CN114688953A (en)

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CN202011616310.8A CN114688953A (en) 2020-12-30 2020-12-30 Circuit structure for realizing non-inductive BLDC rotor position detection based on MCU detection commutation signal

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