阅读说明：本技术 用于反电动势过零检测的无传感器电路及相关方法 (Sensorless circuit for back electromotive force zero-crossing detection and related method ) 是由 横尾哲 于 2020-09-29 设计创作，主要内容包括：本发明题为“用于反电动势过零检测的无传感器电路及相关方法”。本发明提供了一种无传感器检测电路,该无传感器检测电路包括第一电压调节电路,该第一电压调节电路使用三个输入电压中的一个输入电压在第一节点处提供第一输出电压。第二电压调节电路使用三个输入电压中的所有三个输入电压或仅两个输入电压在第二节点处提供第二输出电压。第二电压调节电路充当用于检测电机的过零事件的内部虚拟中性点。差分放大器与第一节点和第二节点耦接并且在第三节点处输出第三输出电压。基准缓冲器具有基准电压输入并且在第四节点处提供第四输出电压。比较器与第三节点和第四节点耦接并且在第五节点处输出第五输出电压,该第五电压指示过零事件。(The invention provides a sensorless circuit and related method for back electromotive force zero-crossing detection. A sensorless detection circuit includes a first voltage regulation circuit that provides a first output voltage at a first node using one of three input voltages. The second voltage regulating circuit provides a second output voltage at the second node using all three of the three input voltages or only two of the three input voltages. The second voltage regulating circuit acts as an internal virtual neutral point for detecting a zero crossing event of the electric machine. The differential amplifier is coupled to the first node and the second node and outputs a third output voltage at a third node. The reference buffer has a reference voltage input and provides a fourth output voltage at a fourth node. A comparator is coupled to the third node and the fourth node and outputs a fifth output voltage at a fifth node, the fifth voltage indicative of a zero-crossing event.)

1. A sensorless detection circuit, the sensorless detection circuit comprising:

a first voltage regulation circuit configured to provide a first output voltage at a first node using one of a first input voltage, a second input voltage, and a third input voltage;

a second voltage regulation circuit configured to provide a second output voltage at a second node using the first input voltage, the second input voltage, and the third input voltage;

a differential amplifier having a first input coupled to the first node and a second input coupled to the second node and configured to provide a third output voltage at a third node;

a reference buffer having a reference voltage input and configured to provide a fourth output voltage at a fourth node; and

a comparator having a first input coupled to the third node and a second input coupled to the fourth node and configured to provide a fifth output voltage at a fifth node;

wherein the sensorless detection circuit is configured to detect a zero crossing event of a three-phase motor.

2. The circuit of claim 1, wherein the first voltage regulation circuit comprises a plurality of resistive dividers each comprising a first resistor having a first resistance and a second resistor having a second resistance.

3. The circuit of claim 2, wherein the second voltage regulation circuit comprises a plurality of resistive dividers each comprising a third resistor and a fourth resistor, wherein each third resistor comprises a third resistance that is three times the first resistance, and wherein each fourth resistor comprises a fourth resistance that is three times the second resistance.

4. The circuit of claim 1, wherein the first voltage regulation circuit comprises a plurality of first switches, each first switch comprising a fifth resistor.

5. A sensorless detection circuit, the sensorless detection circuit comprising:

a first voltage regulation circuit configured to provide a first output voltage at a first node using one of a first input voltage, a second input voltage, or a third input voltage;

a second voltage regulation circuit configured to provide a second output voltage at a second node using two of the first input voltage, the second input voltage, or the third input voltage;

a differential amplifier having a first input coupled to the first node and a second input coupled to the second node and configured to provide a third output voltage at a third node;

a reference buffer having a reference voltage input and configured to provide a fourth output voltage at a fourth node; and

a comparator having a first input coupled to the third node and a second input coupled to the fourth node and configured to provide a fifth output voltage at a fifth node;

wherein the sensorless detection circuit is configured to detect a zero crossing event of a three-phase motor.

6. The circuit of claim 5, wherein the first voltage regulation circuit comprises a plurality of resistive dividers each comprising a first resistor having a first resistance and a second resistor having a second resistance.

7. The circuit of claim 6, wherein the second voltage regulation circuit comprises a plurality of resistive dividers each comprising a third resistor and a fourth resistor, wherein each third resistor comprises a third resistance that is twice the first resistance, and wherein each fourth resistor comprises a fourth resistance that is twice the second resistance.

8. The circuit of claim 5, wherein the first voltage regulation circuit comprises a plurality of first switches each comprising a fifth resistance.

9. A method of sensorless detection of zero crossing events of a three-phase motor, the method comprising:

electrically coupling a first voltage regulation circuit with a three-phase brushless DC motor and providing a first output voltage at a first node using one of a first input voltage, a second input voltage, or a third input voltage using the first voltage regulation circuit;

electrically coupling a second voltage regulation circuit with the brushless DC motor and providing a second output voltage at a second node using at least two of the first input voltage, the second input voltage, or the third input voltage using the second voltage regulation circuit;

electrically coupling a first input of a differential amplifier with the first node, electrically coupling a second input of the differential amplifier with the second node, and providing a third output voltage at a third node using the differential amplifier;

providing a reference buffer having a reference voltage input, said reference buffer providing a fourth output voltage at a fourth node; and

electrically coupling a first input of a comparator with the third node, electrically coupling a second input of the comparator with the fourth node, and providing a fifth output voltage at a fifth node using the comparator;

wherein the fifth output voltage is indicative of a zero crossing event of the brushless DC motor.

10. The method of claim 19, wherein providing the second output voltage at the second node using the second voltage regulation circuit comprises using all three of the first input voltage, the second input voltage, and the third input voltage.

Technical Field

Aspects of this document generally relate to circuits and methods for back electromotive force (BEMF) zero-crossing detection.

Background

Three-phase motors use power applied to the motor in three different phases to rotate the motor. These phases usually involve separate electrical connections and are usually referred to as U-phase, V-phase and W-phase.

Disclosure of Invention

Embodiments of the sensorless detection circuit may include: a first voltage regulation circuit configured to provide a first output voltage at a first node using one of a first input voltage, a second input voltage, and a third input voltage; a second voltage regulation circuit configured to provide a second output voltage at a second node using the first input voltage, the second input voltage, and a third input voltage; a differential amplifier having a first input coupled to the first node and a second input coupled to the second node and configured to provide a third output voltage at a third node; a reference buffer having a reference voltage input and configured to provide a fourth output voltage at a fourth node; and a comparator having a first input coupled to the third node and a second input coupled to the fourth node and configured to provide a fifth output voltage at a fifth node; wherein the sensorless detection circuit is configured to detect a zero crossing event of the three-phase motor.

Implementations of the sensorless detection circuit may include one, all, or any of the following:

the sensorless detection circuit may not use a hall effect sensor.

The first voltage regulation circuit may include a plurality of resistive voltage dividers each including a first resistor having a first resistance and a second resistor having a second resistance.

The second voltage regulating circuit may include a plurality of resistive voltage dividers each including a third resistor and a fourth resistor. Each third resistor may have a third resistance that is three times the first resistance, and each fourth resistor may have a fourth resistance that is three times the second resistance.

The first voltage regulating circuit may include a plurality of first switches. Each first switch may have a fifth resistance.

The second voltage regulating circuit may include a plurality of second switches. Each second switch may have a sixth resistance that is three times the fifth resistance.

The first node may be connected to the third node through at least one resistor not included in the differential amplifier.

The second node may be connected to the fourth node through at least one resistor not included in the differential amplifier or the comparator.

The second voltage regulating circuit may include an internal virtual neutral.

Embodiments of the sensorless detection circuit may include: a first voltage regulation circuit configured to provide a first output voltage at a first node using one of a first input voltage, a second input voltage, and a third input voltage; a second voltage regulation circuit configured to provide a second output voltage at a second node using two of the first input voltage, the second input voltage, and the third input voltage; a differential amplifier having a first input coupled to the first node and a second input coupled to the second node and configured to provide a third output voltage at a third node; a reference buffer having a reference voltage input and configured to provide a fourth output voltage at a fourth node; and a comparator having a first input coupled to the third node and a second input coupled to the fourth node and configured to provide a fifth output voltage at a fifth node; wherein the sensorless detection circuit is configured to detect a zero crossing event of the three-phase motor.

Implementations of the sensorless detection circuit may include one, all, or any of the following:

the sensorless detection circuit may not use a hall effect sensor.

The first voltage regulation circuit may include a plurality of resistive voltage dividers each including a first resistor having a first resistance and a second resistor having a second resistance.

The second voltage regulating circuit may include a plurality of resistive voltage dividers each including a third resistor and a fourth resistor. Each third resistor may have a third resistance that is twice the first resistance and each fourth resistor may have a fourth resistance that is twice the second resistance.

The first voltage regulating circuit may include a plurality of first switches each having a fifth resistance.

The second voltage regulating circuit may include a plurality of second switches each having a sixth resistance that is twice the fifth resistance.

The first node may be connected to the third node through at least one resistor not included in the differential amplifier.

The second node may be connected to the fourth node through at least one resistor not included in the differential amplifier or the comparator.

The second voltage regulating circuit may include an internal virtual neutral.

Embodiments of a sensorless detection method of zero crossings of a three-phase motor may include: electrically coupling a first voltage regulation circuit with a three-phase brushless direct current (BLDC) motor, and providing a first output voltage at a first node using one of a first input voltage, a second input voltage, and a third input voltage using the first voltage regulation circuit; electrically coupling a second voltage regulation circuit to the BLDC motor, and providing a second output voltage at a second node using at least two of the first input voltage, the second input voltage, and the third input voltage using the second voltage regulation circuit; electrically coupling a first input of a differential amplifier to a first node, electrically coupling a second input of the differential amplifier to a second node, and providing a third output voltage at a third node using the differential amplifier; providing a reference buffer having a reference voltage input, the reference buffer providing a fourth output voltage at a fourth node; and electrically coupling a first input of the comparator with the third node, electrically coupling a second input of the comparator with the fourth node, and providing a fifth output voltage at the fifth node using the comparator; wherein the fifth output voltage is indicative of a zero crossing event of the BLDC motor.

Embodiments of the sensorless detection method of zero crossings of a three-phase electric machine may comprise one, all or any of the following:

providing the second output voltage at the second node using the second voltage regulating circuit may include using all three of the first input voltage, the second input voltage, and the third input voltage.

The first voltage regulation circuit may include a plurality of resistive voltage dividers each including a first resistor having a first resistance and a second resistor having a second resistance.

The second voltage regulation circuit may include a plurality of resistive voltage dividers each including a third resistor having a third resistance and a fourth resistor having a fourth resistance. The third resistance may be twice or three times the first resistance, and the fourth resistance may be twice or three times the second resistance.

The above and other aspects, features and advantages will be apparent to those of ordinary skill in the art from the detailed description and drawings, and from the claims.

Drawings

Embodiments will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and:

FIG. 1 is a circuit diagram representatively illustrating an embodiment of a sensorless circuit for BEMF zero-crossing detection;

FIG. 2 is a circuit diagram representatively illustrating another embodiment of a sensorless circuit for BEMF zero-crossing detection;

FIG. 3 is a circuit diagram representatively illustrating another embodiment of a sensorless circuit for BEMF zero-crossing detection; and is

Fig. 4 is a circuit diagram representatively illustrating a controller circuit for a three-phase motor, including a sensorless circuit for BEMF zero-crossing detection.

Detailed Description

The present disclosure, aspects, and embodiments thereof, are not limited to the specific components, assembly processes, or method elements disclosed herein. Many additional components, assembly procedures, and/or method elements known in the art consistent with the intended sensorless circuit and associated methods for back emf zero crossing detection will be apparent for use with particular embodiments of the present disclosure. Thus, for example, although particular embodiments are disclosed, such embodiments and implementing components may include such sensorless circuits and related methods for back emf zero crossing detection and any shapes, sizes, styles, types, models, versions, measurements, concentrations, materials, quantities, method elements, steps, etc., of implementing components and methods known in the art consistent with the intended operations and methods.

During operation of a three-phase motor, such as at start-up and at other times during operation, the motor controller needs to detect the position and rotational speed of the rotor of the motor. Accurately doing so may allow for precise motor control by adjusting the timing of the supply voltage applied to the motor windings. In some motors, hall sensors may be used to detect rotor position, but for sensorless motors, a back electromotive force (BEMF) signal may be used to detect position, such as by comparing the BEMF signal to a voltage to determine when the motor crosses zero (a zero-crossing event). Back electromotive force (BEMF) zero crossing detection is used to determine the position of the rotor of the motor relative to the stator of the motor at a given point in time. The ability to repeatedly determine the position of the rotor relative to the stator allows for accurate timing when energizing the different windings of the motor for the motor to operate efficiently.

Embodiments of the sensorless circuit for BEMF zero-crossing detection disclosed herein detect zero-crossing points of a rotor of a three-phase electric machine without using hall sensors. Particular embodiments of the sensorless circuit for BEMF zero-crossing detection disclosed herein also exclude or move the virtual neutral point.

Referring now to fig. 1, an embodiment of a sensorless circuit (circuit) 2 for BEMF zero-crossing detection is depicted. The circuit is coupled to a motor, which in this embodiment is a three-phase brushless direct current (BLDC) motor (motor) 4 powered by a supply voltage VCC through Pulse Width Modulation (PWM) using a six transistor combination. The transistors are configured/operated such that at any given time during operation of the motor, two of the motor windings are PWM driven while the third winding is not powered. A BEMF signal is generated in the unenergized winding as it rotates through the magnetic field of the motor and may be used to detect zero-crossing points of the rotor without the use of hall sensors.

To detect the zero-crossing point, the circuit 2 includes a virtual neutral point 6 formed by using three resistors RN. The phase U, phase V, phase W and COM voltages are then attenuated to a lower voltage, such as 5V or 3.3V, using a resistive divider comprising R1 and R2 resistors, respectively. The analog divided/buck COM voltage is fed into the input of each of the three comparators, each comparator also receiving one of the analog divided/buck voltages of phase U, phase V or phase W. Each comparator is coupled to the supply voltage VDD and flips its output when the analog divided/buck COM voltage crosses its point equal to the other input voltage of the comparator, which would be the BEMF signal of the unpowered winding. In this manner, the BEMF signal is used to detect zero crossings, and this information can be fed back to the transistor to use PWM to adjust the timing of applying VCC to the winding. An exemplary signal is depicted on the right side of the uppermost comparator, representatively illustrating how the signal from each comparator can be switched between a first value and a second value.

For sensorless BEMF detection, it is desirable to have a circuit with low current consumption and high accuracy. For the circuit of fig. 1, to achieve low current consumption, it is desirable to configure the RN resistor to have the highest resistance possible. However, to achieve high accuracy of BEMF detection with the circuit of fig. 1, it is desirable to configure the RN resistor to have the lowest possible resistance. Therefore, these goals contradict each other.

To perform a zero-crossing sensorless BEMF detection using the circuit of fig. 1, it is desirable that the virtual neutral point 6 and the motor midpoint COM will have the same voltage, so that when the circuit indicates a zero-crossing, the BEMF voltage and the motor midpoint voltage are exactly equal. The lower the resistance of the RN resistor, the closer this ideal condition can be, but as shown, this increases current consumption. Therefore, a mismatch voltage is generated between the motor midpoint COM and the virtual neutral point 6. In the example of fig. 1, VCC is 48V, the voltage at the motor midpoint COM is 24V, R1+ R2 is 100kohm, and RN is 1 kohm. The virtual neutral point voltage can be calculated as follows:

the above calculation results in a voltage mismatch Δ COM of-79.73 mV. The RN current can be calculated as follows:

therefore, when the resistance value of RN increases, high accuracy BEMF zero-crossing detection cannot be performed. As the resistance decreases, the current consumption also increases.

Referring now to fig. 2, fig. 2 representatively illustrates another embodiment of a sensorless circuit (circuit) 8 for BEMF zero-crossing detection. The circuit 8 is coupled to a three-phase brushless direct current (BLDC) motor (motor) 10. As will be explained, the resistor RN has been completely removed and instead an "internal virtual neutral" 12 is formed using a resistor divider 14 and other resistors and switches. The resistor R1 and the resistor R2 form voltage dividers each coupled to one of the nodes N1, N2, N3 to provide divided/stepped down voltages at nodes N4, N5, and N6. Each of the nodes N4-N6 is selectively coupled to the node N10 through a resistor Rs and one of the select Switches (SW)16, and one or more elements not shown in the circuit diagram are used to select which select switch SW is in the closed configuration. The switch in the closed configuration passes the divided down/buck analog BEMF voltage signal to node N10 as one input to differential amplifier 18.

Fig. 2 shows only one of the switches SW in a closed configuration, and indeed at any given time, only one of the phase voltages will be delivered to node N10 to provide the BEMF signal for that phase, but the switches SW may be closed/opened in sequence, with one switch at a time in a closed configuration, to successively detect zero-crossings using the BEMF signal for each winding. When any given switch SW is closed, e.g., phase U switch SW, the other two phase signals (phase V and phase W in this case) do not affect the voltage signal at node N10 since the other two switches SW are open.

Referring back to nodes N1, N2, and N3, resistors 3R1 and 3R2 form voltage dividers that are each coupled to one of the switches in nodes N1-N3 to provide divided/stepped down voltages at nodes N7, N8, and N9. Each of the nodes N7-N9 is coupled to node N11 through a resistor 3Rs and a switch 3 SW. The switches 3SW are all shown in a closed configuration, and in fact they will remain permanently in a closed configuration, so that each of the voltages at N7-N9 affects the voltage at N11. The voltage signal at node N11 is the other input to the differential amplifier 18.

The resistor divider formed by resistors 3R1 and 3R2 and resistor 3Rs and switch 3SW together with the connecting elements will form an internal virtual neutral point 12. The internal virtual neutral 12 allows node N11 to have a voltage representing the motor midpoint voltage COM, but without the use of the previous Y-connected resistor RN of the circuit of fig. 1. This allows the circuit of fig. 2 to detect zero crossings without degrading accuracy due to the RN resistor. The 3R1 resistor, the 3R2 resistor, and the 3Rs resistor in the circuit of fig. 2 are configured to have a resistance three times the resistance of the R1 resistor, the R2 resistor, and the Rs resistor, respectively, and the 3SW switch is configured to have a resistance three times the resistance of the SW switch to more accurately represent the BEMF signal and the COM signal at the N10 node and the N11 node, respectively, as inputs to the differential amplifier 18. Therefore, the use of each 3SW switch is only to provide a resistance that matches three times the resistance of the SW switch, and it is for this reason that the 3SW switches are included in the circuit even though they are always kept in a closed configuration.

The internal virtual neutral signal side and the BEMF signal side are thus separated, and the three on the internal virtual neutral side are connected in parallel. The resistance on each parallel line on the internal virtual neutral side (including the resistance of the resistor and the resistance of the switch) is thus three times the resistance on the BEMF side. This is done to more accurately detect when a zero crossing occurs. Thus, the voltage input to the differential amplifier 18 from each parallel line of the internal virtual neutral 12 is reduced or "burned" by three times the voltage burned off the voltage input from the BEMF signal so that the input voltage values on the input lines of the differential amplifier match. The differential amplifier 18 can then accurately signal when the voltage values from the virtual internal neutral point 12 and the BEMF side alternate between equal and unequal, thus signaling a zero crossing.

Also shown in fig. 2 is a reference buffer 20, which reference buffer 20 is a voltage follower having a supply voltage VDD and a reference voltage VREF. The output of the reference buffer is coupled to node N13, which is the input of comparator 22 at node N13. The output of differential amplifier 18 is the other input of comparator 22, so that the input voltage of the comparator is the voltage at nodes N12 and N13, while the comparator (and differential amplifier) is also supplied with the supply voltage VDD. The reference voltage VREF is used to provide an appropriate voltage input at node N13 so that the comparator can signal that a zero crossing has been detected when the output voltage from the differential amplifier 18 at node N12 switches between being equal to the voltage at N13 and not equal to the voltage at N13.

The resistive divider may be adjusted so that the voltage level provided to the differential amplifier is within its operating range, otherwise the rating of the low voltage components of the circuit is adjusted. The resistive voltage divider itself may be used to attenuate the high voltage signal to a low voltage, such as 5V or 3.3V, so that the circuit may be used to detect zero crossings even on high voltage motors. The circuit of fig. 2 also allows BEMF zero-crossing detection over a wide voltage range from negative to positive voltage using a resistive divider and a differential amplifier.

The decay rate may be determined/configured as follows:

the resistance of Ro can be tailored as follows:

resistors Ro and Rf are provided between nodes N10 and N12, respectively, and also between nodes N11 and N13, to tailor gain and provide low pass filters, such as for common mode noise rejection, which may be an advantage of receiving the BEMF signal and the internal virtual neutral signal as differential inputs to the differential amplifier. The gain of the differential amplifier 18 can be customized as follows, where RSW is the resistance of the switch SW:

the total gain is the attenuation ratio multiplied by the differential amplifier gain.

The comparator 22 of fig. 2 may use the BEMF voltage of one of the phases to detect the zero crossing without being affected by any change in the output of the reference buffer 20, since the reference buffer amplifier output is coupled to both inputs of the comparator through node N13 and through the differential amplifier 18 to node N12. Therefore, since the differential amplifier 18 commonly uses the same reference voltage as the comparator 22, the reference voltage error will not affect the high accuracy BEMF zero-crossing detection.

With the circuit of fig. 2, the output of the differential amplifier 18 at zero crossing is the same as the output of the reference buffer 20.

Fig. 3 representatively illustrates another embodiment of a sensorless circuit (circuit) 24 for back emf zero crossing detection. Circuit 24 is coupled to a three-phase brushless direct current (BLDC) motor (motor) 26 and is identical to the circuit of fig. 2, except that an internal virtual neutral point 28 uses two phase voltage inputs instead of all three phase voltage inputs. On the BEMF side, the phase U switch is depicted as closed, so that the BEMF signal from phase U is selected to be input to the differential amplifier through node N10. On the internal virtual neutral side, the switches corresponding to the other two phases (phase V and phase W) are closed, while the switches corresponding to the phase U signal are open. Because only two phase signals are used for the internal virtual neutral side, the resistor on the internal virtual neutral side is only twice as many as the resistor on the BEMF side, not three times as with the circuit of fig. 2. Thus, the resistor 2R1 and the resistor 2R2 of the voltage divider of the virtual internal neutral point 28 are each twice the resistance of the R1 resistor and the R2 resistor, respectively, of the voltage divider on the BEMF side, the 2Rs resistor is twice the resistance of the Rs resistor, and the 2SW switch is twice the resistance of the SW switch.

Fig. 3 shows that each selection signal (selectable phase) signaling opening/closing of one of the BEMF side switches SW is coupled to the virtual neutral point switch 2SW of the same phase through an inverter. Thus, the corresponding 2SW switch on the internal virtual neutral side is closed/open, so that when the BEMF side switch is open for a phase, the virtual neutral side switch of the same phase is closed, and vice versa. During operation of the circuit of fig. 3, the switches may be cycled on and off sequentially, as discussed above with respect to the circuit of fig. 2.

With the circuit of fig. 3, the output of the differential amplifier is the same as the output of the reference buffer at zero crossing.

The circuits of fig. 2 and 3 may use the BEMF signal of a three-phase BLDC motor to detect zero-crossings when one winding is in a high-Z (high inductance) state and both phases are PWM driven or when all phases are high-Z.

For the circuits shown in the figures, any portion of the circuit that receives one or more input voltages and outputs one or more regulated output voltages may be referred to as a "voltage regulation circuit". For example, referring to fig. 2 and 3, on the BEMF side, any combination of SW switches, Rs resistors, and/or resistor dividers (which receive one or more input voltages and output one or more regulated output voltages) may be referred to as a voltage regulation circuit. Thus, any of the following combinations of circuit elements may be accurately referred to as a voltage regulating circuit: one or more resistive dividers, one or more Rs resistors, one or more SW switches plus one or more Rs resistors, or one or more Rs resistors plus one or more resistive dividers, or one or more resistive dividers plus one or more Rs resistors plus one or more SW switches. Similarly, on the internal virtual neutral side of the circuits of fig. 2 and 3, any combination of a resistor divider, a 3Rs/2Rs resistor, and/or a 3SW/2SW switch may be referred to as a voltage regulation circuit.

As other examples, referring to fig. 2, the sensorless detection circuit 8 may be considered to include a first voltage regulation circuit that includes the top three resistive voltage dividers (formed by R1 and R2 resistors), three Rs resistors, and three SW switches. The first voltage regulation circuit provides an output voltage at N10 using only one of the three input voltages (phase U voltage, phase V voltage, phase W voltage). The circuit 8 may also be considered to include a second voltage regulation circuit comprising the bottom three resistive voltage dividers (formed by 3R1 and 3R2 resistors), three 3Rs resistors, and three 3SW switches. The second voltage regulation circuit provides an output voltage at N11 using all three of the three input voltages (phase U voltage, phase V voltage, phase W voltage).

Further, referring to fig. 3, the sensorless detection circuit 24 may be considered to include a first voltage regulation circuit that includes the top three resistive voltage dividers (formed by R1 and R2 resistors), three Rs resistors, and three SW switches. The first voltage regulation circuit provides an output voltage at N10 using only one of the three input voltages (phase U voltage, phase V voltage, phase W voltage). Circuit 24 may also be considered to include a second voltage regulation circuit that includes the bottom three resistive voltage dividers (formed by the 2R1 resistor and the 2R2 resistor), three 2Rs resistors, and three 2SW switches. The second voltage regulation circuit provides an output voltage at N11 using only two of the three input voltages (phase U voltage, phase V voltage, phase W voltage).

Each element of the circuit (such as a resistor, switch, differential amplifier, comparator, etc.) may be described as having at least two terminals (and three terminals in the case of a differential amplifier, reference buffer and comparator), each terminal of each element being connected to one of the nodes of the circuit.

The voltages discussed herein may be referred to as "input" voltages and "output" voltages. For example, referring to fig. 2-3, the voltages at nodes N1-N3 (phase voltages and BEMF voltages) may all be referred to as the input voltage of a resistive voltage divider, and the divided/dropped voltages at nodes N4-N9 may each be referred to as the output voltage of or from the resistive voltage divider. The voltages at nodes N10 and N11 are the output voltages of the switches (SW, 3SW, 2SW) (in an embodiment, the voltage at node N11 may be at least partially the output voltage of switch 2SW/3SW and also at least partially the output voltage of the Ro resistor between nodes N11 and N13). The voltages at nodes N10 and N11 are also the input voltages of the differential amplifier. The voltage at node N12 is the output voltage of/from the differential amplifier (in an embodiment, the voltage at node N12 may be at least partially the output voltage of the differential amplifier and also at least partially the output voltage of the Rf resistor between nodes N10 and N12). The voltage at node N12 is also the input voltage to the comparator. The voltage at node N13 is the output voltage of the reference buffer (in an embodiment, the voltage at node N13 may be at least partially the output voltage of the reference buffer and also at least partially the output voltage of the Rf resistor between the N11 node and the N13 node). The voltage at node N13 is also the input voltage to the comparator, and so on.

Fig. 4 illustrates an example of a controller Integrated Circuit (IC)30 that may include one or more of the sensorless circuit elements disclosed herein. The controller IC is shown having I/O terminals, such as UH, UOUT, VH, VOUT, WH, etc., which may be implemented as contact pads, pins, leads, etc. The control IC is coupled to a three-phase brushless direct current (BLDC) motor (motor) 32. COM nodes are considered to have an "external" virtual neutral 34. By modifying the controller/detection circuitry to use an internal virtual neutral within the controller IC itself, the current consumption of the controller/detection circuitry, such as those disclosed in fig. 2-3, may be reduced, and the number of components and IC terminals/pins may also be reduced accordingly.

In contrast to the "external" neutral point of the circuit of fig. 1, the virtual neutral point of the circuits of fig. 2 and 3 is an "internal" neutral point, which reduces current consumption. The circuits of fig. 2-3 may allow detection of zero crossings even when no motor midpoint is provided and no external virtual neutral is used. The circuit may allow high accuracy sensorless zero-crossing detection in a three-phase BLDC motor driver even at high voltages while consuming low power.

In an embodiment, all of the components of the circuits disclosed herein are located within an Integrated Circuit (IC) of a semiconductor device, where the IC is electrically coupled to a three-phase BLDC motor as shown in the figures to allow control of the motor by the IC and to allow back emf zero-crossing detection by the IC. The circuits disclosed herein may be used in various industries, such as a 48V supply voltage for 5G telecommunications and automotive applications and a BLDC motor using a maximum operating voltage of about 100V.

In various method embodiments, the method may include the following: wherein the first voltage regulating circuit includes a plurality of resistive voltage dividers each including a first resistor having a first resistance and a second resistor having a second resistance.

In various method embodiments, the method may include the following: wherein the second voltage regulating circuit comprises a plurality of resistive dividers each comprising a third resistor having a third resistance and a fourth resistor having a fourth resistance, wherein the third resistance is one of two times and three times the first resistance, and wherein the fourth resistance is one of two times and three times the second resistance.

In various system embodiments, the second voltage regulating circuit includes a plurality of second switches each including a sixth resistance that is three times the fifth resistance.

In various system embodiments, the first node may be connected to the third node through at least one resistor, and the differential amplifier does not include the at least one resistor.

In various system embodiments, the second node may be connected to the fourth node through at least one resistor, wherein the differential amplifier does not include the at least one resistor and the comparator does not include the at least one resistor.

In various system embodiments, the second voltage regulating circuit may include an internal virtual neutral.

Where the above description refers to particular embodiments of sensorless circuits and related methods for back emf zero crossing detection and implementing components, subcomponents, methods and submethods, it should be readily apparent that various modifications may be made without departing from the spirit thereof and that these embodiments, implementing components, subcomponents, methods and submethods may be applied to other sensorless circuits and related methods of back emf zero crossing detection.