CN107565857B - Electronic circuit and method for driving a polyphase electric motor having a plurality of motor windings - Google Patents
Electronic circuit and method for driving a polyphase electric motor having a plurality of motor windings Download PDFInfo
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- CN107565857B CN107565857B CN201710841680.3A CN201710841680A CN107565857B CN 107565857 B CN107565857 B CN 107565857B CN 201710841680 A CN201710841680 A CN 201710841680A CN 107565857 B CN107565857 B CN 107565857B
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- 238000004804 winding Methods 0.000 title claims abstract description 127
- 238000000034 method Methods 0.000 title claims abstract description 44
- 230000002441 reversible effect Effects 0.000 claims abstract description 19
- 230000001052 transient effect Effects 0.000 claims description 35
- 230000007274 generation of a signal involved in cell-cell signaling Effects 0.000 claims description 23
- 238000005259 measurement Methods 0.000 claims description 22
- 238000005070 sampling Methods 0.000 claims description 6
- 230000001133 acceleration Effects 0.000 abstract 1
- 238000001514 detection method Methods 0.000 description 8
- 238000010586 diagram Methods 0.000 description 5
- 230000007704 transition Effects 0.000 description 5
- 230000003111 delayed effect Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
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- 230000000979 retarding effect Effects 0.000 description 1
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
- H02P6/182—Circuit arrangements for detecting position without separate position detecting elements using back-emf in windings
Abstract
The invention relates to an electronic circuit and a method for driving a polyphase electric motor having a plurality of motor windings. A motor control circuit and associated techniques can adjust the phase of the motor drive to maintain the rotational reference position of the motor at the same relative phase as the zero current in the motor windings and the motor acceleration and deceleration at different motor speeds. A motor control circuit and associated techniques detect a zero crossing of current in a motor winding by detecting a reverse current in a half-bridge circuit used to drive the motor winding.
Description
The present application is a divisional application filed on 2013, 8/13 entitled "electronic circuit and method for automatically adjusting the phase of a drive signal applied to a motor based on a zero current detected in a winding of the motor and for detecting the zero current" patent application 201380056237.5.
Technical Field
The present invention relates generally to motor control circuits and, more particularly, to a motor control circuit capable of providing automatic adjustment of the phase of a drive signal applied to a motor and capable of detecting zero current in the windings of the motor.
Background
Circuits for controlling and driving brushless direct current (BLDC) motors are known. In some arrangements, the circuit provides a phase advance (phase advance) of a drive signal that drives the motor, the phase advance being related to the rotational speed of the motor, or to a measured total motor current. However, such a circuit can only provide one relationship, or a few relationships, between phase advance and rotational speed. Furthermore, external components and binning of the motor control Integrated Circuit (IC) may be required to set parameters for each motor or each motor application.
Some known motor drive circuits are described in U.S. patent 7,590,334 issued on 9/15 of 2009, U.S. patent 7,747,146 issued on 6/29 of 2010, and U.S. patent application 13/271,723 filed on 10/12 of 2011, all of which are hereby incorporated by reference in their entirety and assigned to the assignee of the present invention.
BLDC motors can exhibit different efficiency behavior and speed when used in different applications. For example, the same BLDC motor can be used with different fan blade arrangements in different applications. Different types of BLDC motors can also exhibit different efficiency behavior and speed.
Motor noise, vibration and efficiency are affected by various characteristics. One such feature is the phase of the current, which appears in the motor windings relative to the rotational position of the motor. In particular, the phase of the current can lag or lead, respectively, the reference rotational position of the motor as the motor speed increases or decreases. Furthermore, at high motor speeds, the current in the motor windings can tend to lag the reference position of the motor.
In view of the foregoing, it is desirable to provide a motor control circuit and associated method that is capable of generating a motor drive signal having an automatic phase adjustment determined from a detected phase difference between a motor winding current and a motor rotational position.
In view of the foregoing, it would also be desirable to provide a motor control circuit and associated method that is capable of detecting the phase of current in the motor windings, for example, by detecting a zero crossing of the current.
Disclosure of Invention
The present invention provides a motor control circuit and associated method that is capable of generating a motor drive signal having an automatic phase adjustment determined from a detected phase difference between a motor winding current and a motor rotational position.
The present invention also provides a motor control circuit and associated method that is capable of detecting the phase of current in the motor windings, for example by detecting a zero crossing of the current.
According to one aspect of the invention, a method of driving a multi-phase motor having a plurality of motor windings comprises: generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings; generating a position reference signal indicative of a reference position of angular rotation of the motor; comparing a phase of the zero-current signal with a phase of the position reference signal to generate a phase comparison signal; generating a plurality of modulated signals, each modulated signal having a phase related to a value of the phase comparison signal; and generating a plurality of motor drive signals to the plurality of motor windings from the plurality of modulation signals.
In some embodiments, the above-described methods can include one or more of the following.
In some embodiments of the method, generating the position reference signal comprises:
the hall sensor signal is generated with a hall sensor disposed proximate to the motor.
In some embodiments of the method, generating the position reference signal comprises:
generating a back electromotive force (back EMF) signal with a back EMF module coupled to at least one of the plurality of motor windings.
In some embodiments of the method, generating the position reference signal comprises:
stopping the motor drive signal to at least one of the plurality of motor windings during a time window proximate to the motor reaching a reference position; and
the reference position during the time window is detected by a zero crossing of a back emf signal.
In some embodiments of the method, generating the plurality of modulated signals comprises:
providing a look-up table in which modulation values corresponding to a shape of at least one of the plurality of modulation signals are stored;
generating a first continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value;
adding a value associated with the phase comparison signal to the first continuous sawtooth ramp signal to generate a second continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values therebetween, wherein the minimum value and the maximum value of the second continuous sawtooth ramp signal and the minimum value and the maximum value of the first continuous sawtooth ramp signal are offset in time by an adjustment time, wherein the adjustment time is associated with the phase comparison signal;
sequentially looking up values in the look-up table using the adjusted continuous sawtooth ramp signal to generate at least one of the plurality of modulation signals; and
at least one other modulation signal having a predetermined phase relationship with at least one of the plurality of modulation signals is generated.
In some embodiments of the method, generating the zero-current signal comprises:
generating the plurality of motor drive signals with a respective plurality of half-bridge circuits coupled to the motor, each half-bridge circuit comprising:
a respective first transistor and second transistor coupled in series;
a respective power supply high voltage node for receiving a high power supply voltage;
a respective power supply low voltage node for receiving a low power supply voltage; and
a respective output node at which a respective one of the plurality of motor drive signals is generated;
detecting a reverse current through at least one of a first transistor or a second transistor of at least one of the plurality of half-bridge circuits, wherein the detecting comprises at least one of:
detecting a voltage at an output node that is higher than the high supply voltage; or
Detecting a voltage at an output node that is lower than the low supply voltage; and
generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings based on detecting the reverse current.
In some embodiments of the method, detecting the reverse current comprises:
the reverse current is detected by sampling the voltage at the output node only over time when both the first transistor and the second transistor are off.
In some embodiments of the method, each of the plurality of motor drive signals comprises:
a respective plurality of pulse width modulated signals, each of the plurality of pulse width signals having a high state comprising a steady state high value proximate to the high supply voltage and a transient high value above the high supply voltage, and each of the plurality of pulse width signals also having a low state comprising a steady state low value proximate to the low supply voltage and a transient low value below the low supply voltage.
According to another aspect of the present invention, an electronic circuit for driving a multi-phase motor having a plurality of motor windings includes a current measurement module configured to generate a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings. The electronic circuit also includes a position measurement module configured to generate a position reference signal indicative of a reference position of angular rotation of the motor. The electronic circuit further includes a modulation signal generation module configured to compare a phase of the zero-current signal with a phase of the position reference signal to generate a phase comparison signal, and configured to generate a plurality of modulation signals each having a phase related to a value of the phase comparison signal. The electronic circuit also includes a drive circuit configured to generate a plurality of motor drive signals to the plurality of motor windings from the plurality of modulation signals.
In some embodiments, the electronic circuitry can include one or more of the following aspects.
In some embodiments of the electronic circuit, the position measurement module is further configured to generate the position signal from a hall signal generated by a hall sensor disposed proximate to the motor.
In some embodiments of the electronic circuit, the position measurement module is further configured to generate a position signal from the back EMF signal generated in the motor winding.
In some embodiments of the electronic circuitry, generating the position reference signal comprises:
stopping the motor drive signal to at least one of the plurality of motor windings during a time window proximate the motor reaching the reference position; and detecting the reference position during the time window by a zero crossing of the back EMF signal.
In some embodiments of the electronic circuit, the modulation signal generation module comprises:
a look-up table in which modulation values corresponding to a shape of at least one of the plurality of modulation signals are stored;
a sawtooth generator configured to generate a first continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value;
a timing/phase error detector coupled to receive a signal representative of the zero current signal, coupled to receive a signal representative of the position reference signal, and configured to generate a signal representative of the phase comparison signal; and
a summing module configured to add a value associated with the phase comparison signal to the first continuous sawtooth ramp signal to generate a second continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values therebetween, wherein the minimum value and the maximum value of the second continuous sawtooth ramp signal are offset in time from the minimum value and the maximum value of the first continuous sawtooth ramp signal by an adjustment time, wherein the adjustment time is associated with the phase comparison signal, wherein the adjusted continuous sawtooth ramp signal is used to sequentially look up values in the look-up table to generate at least one of the plurality of modulation signals and is further used to generate at least one other modulation signal having a predetermined phase relationship with the at least one of the plurality of modulation signals.
In some embodiments, the electronic circuitry further comprises:
a plurality of half-bridge circuits coupled to the motor and configured to generate the plurality of motor drive signals, each half-bridge circuit comprising:
a respective first transistor and second transistor coupled in series;
a respective power supply high voltage node for receiving a high power supply voltage;
a respective power supply low voltage node for receiving a low power supply voltage; and
a respective output node at which a respective one of the plurality of motor drive signals is generated;
at least one comparator configured to generate a respective at least one comparator output signal indicative of a reverse current through at least one of the first transistor or the second transistor of at least one of the plurality of half-bridge circuits by detecting at least one of:
a voltage at an output node higher than the high supply voltage; or
A voltage at the output node that is lower than the low supply voltage; and
a processor configured to generate a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings as a function of at least one comparator output signal.
In some embodiments of the electronic circuit, the detecting comprises:
the reverse current is detected by sampling the voltage at the output node only at times when both the first and second transistors are off.
In some embodiments of the electronic circuit, each of the plurality of motor drive signals comprises:
a respective plurality of pulse width modulated signals, each of the plurality of pulse width signals having a high state comprising a steady state high value near a high supply voltage and a transient high value above the high supply voltage, and each of the plurality of pulse width signals also having a low state comprising a steady state low value near a low supply voltage and a transient low value below the low supply voltage.
In accordance with another aspect of the invention, a method of driving a multi-phase motor having a plurality of motor windings includes generating a motor drive signal with a half-bridge circuit coupled to the motor. The half-bridge circuit comprises a first transistor or a second transistor coupled in series; a power supply high voltage node for receiving a high power supply voltage; a power low supply node for receiving a low supply voltage; and an output node at which a motor drive signal is generated. The method also includes detecting a reverse current through at least one of the first transistor or the second transistor. The detecting comprises at least one of: detecting a voltage at an output node that is higher than the high supply voltage; or detecting a voltage at the output node that is lower than the low supply voltage. The method also includes generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings based on detecting the reverse current.
In some embodiments, the above-described methods can include one or more of the following aspects.
In some embodiments of the method, detecting the reverse current comprises:
the reverse current is detected by sampling the voltage at the output node only over time when both the first transistor and the second transistor are off.
In some embodiments of the method, the motor drive signal comprises:
a plurality of pulse width modulated signals, each of the plurality of pulse width signals having a high state comprising a steady state high value proximate to the high supply voltage and a transient high value above the high supply voltage, and each of the plurality of pulse width signals also having a low state comprising a steady state low value proximate to the low supply voltage and a transient low value below the low supply voltage.
In some embodiments, the method further comprises:
generating a position reference signal indicative of a reference position of angular rotation of the motor;
comparing a phase of the zero-current signal with a phase of the position reference signal to generate a phase comparison signal;
generating a plurality of modulated signals, each modulated signal having a phase related to a value of the phase comparison signal; and
generating a plurality of motor drive signals to the plurality of motor windings from the plurality of modulation signals.
In some embodiments of the method, generating the position reference signal comprises:
the hall sensor signal is generated with a hall sensor disposed proximate to the motor.
In some embodiments of the method, generating the position reference signal comprises:
generating a back EMF signal with a back EMF module coupled to at least one of the plurality of motor windings.
In some embodiments of the method, generating the position reference signal comprises:
stopping the motor drive signal to at least one of the plurality of motor windings during a time window proximate to the motor reaching a reference position; and detecting the reference position during the time window by a zero crossing of the back EMF signal.
In some embodiments of the method, generating the plurality of modulated signals comprises:
providing a look-up table in which modulation values corresponding to a shape of at least one of the plurality of modulation signals are stored;
generating a first continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value;
adding a value associated with the phase comparison signal to the first continuous sawtooth ramp signal to generate a second continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values therebetween, wherein the minimum value and the maximum value of the second continuous sawtooth ramp signal are offset in time from the minimum value and the maximum value of the first continuous sawtooth ramp signal by an adjustment time, wherein the adjustment time is associated with the phase comparison signal;
sequentially looking up values in a look-up table using the adjusted continuous sawtooth ramp signal to generate at least one of the plurality of modulation signals; and
generating at least one other modulation signal having a predetermined phase relationship with at least one of the plurality of modulation signals, each modulation signal being associated with a respective one of a plurality of Pulse Width Modulation (PWM) signals.
In accordance with another aspect of the invention, an electronic circuit for driving a multi-phase motor having a plurality of motor windings includes a half-bridge circuit coupled to the motor for generating motor drive signals. The half-bridge circuit comprises a first transistor and a second transistor coupled in series; a power supply high voltage node for receiving a high power supply voltage; a power supply low voltage node for receiving a low power supply voltage; and an output node at which a motor drive signal is generated. The electronic circuit further includes at least one comparator configured to generate a respective at least one comparator output signal indicative of a reverse current through at least one of the first transistor or the second transistor by detecting at least one of: a voltage at an output node higher than the high supply voltage; or a voltage at the output node that is lower than the low supply voltage. The electronic circuit further includes a processor configured to generate a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings as a function of the at least one comparator output signal.
In some embodiments, the electronic circuitry can include one or more of the following aspects.
In some embodiments of the electronic circuit, the detecting comprises:
the reverse current is detected by sampling the voltage at the output node only over time when both the first transistor and the second transistor are off.
In some embodiments of the electronic circuit, the motor drive signal comprises:
a plurality of pulse width modulated signals, each of the plurality of pulse width signals having a high state comprising a steady state high value proximate to the high supply voltage and a transient high value above the high supply voltage, and each of the plurality of pulse width signals also having a low state comprising a steady state low value proximate to the low supply voltage and a transient low value below the low supply voltage.
In some embodiments, the electronic circuitry further comprises:
a position measurement module configured to generate a position reference signal indicative of a reference position of angular rotation of the motor; and
a modulation signal generation module configured to compare a phase of the zero-current signal with a phase of the position reference signal to generate a phase comparison signal, and configured to generate a plurality of modulation signals each having a phase related to a value of the phase comparison signal.
In some embodiments of the electronic circuit, the position measurement module is further configured to generate the position signal from a hall signal generated by a hall sensor disposed proximate to the motor.
In some embodiments of the electronic circuit, the position measurement module is further configured to generate the position signal from a back EMF signal generated in a motor winding.
In some embodiments of the electronic circuit, the electronic circuit is configured to stop the motor drive signal to at least one of the plurality of motor windings during a time window proximate to the motor reaching a reference position; and wherein the position measurement module is configured to generate a position reference signal indicative of the reference position during the time window.
In some embodiments of the electronic circuit, the modulation signal generation module comprises:
a look-up table in which modulation values corresponding to a shape of at least one of the plurality of modulation signals are stored;
a sawtooth generator configured to generate a first continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value;
a timing/phase error detector coupled to receive a signal representative of the zero current signal, coupled to receive a signal representative of the position reference signal, and configured to generate a signal representative of the phase comparison signal; and
a summing module configured to add a value related to the phase comparison signal to the first continuous sawtooth ramp signal, to generate a second continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value, wherein the minimum and maximum values of the second continuous sawtooth ramp signal are offset in time from the minimum and maximum values of the first continuous sawtooth ramp signal by an adjustment time, wherein the adjustment time is related to the phase comparison signal, wherein the adjusted continuous sawtooth ramp signal is used to sequentially look up values in the look-up table to generate at least one of the plurality of modulation signals, and further for generating at least one other modulation signal having a predetermined phase relationship with at least one of the plurality of modulation signals, each modulation signal being associated with a respective one of a plurality of Pulse Width Modulation (PWM) signals.
Drawings
The foregoing features of the invention, as well as the invention itself may be more fully understood from the following detailed description of the drawings, in which:
FIG. 1 is a block diagram of an exemplary motor control circuit having a modulation signal generation module and having a current measurement module;
FIG. 2 is a graph illustrating various waveforms associated with the example motor control circuit of FIG. 1, particularly when the motor control circuit is used to provide sinusoidal drive to a motor;
FIG. 3 is another graph illustrating various waveforms associated with the example motor control circuit of FIG. 1, particularly when the motor control circuit is used to provide sinusoidal drive to a motor, and illustrating a phase difference between a current signal and a position reference signal;
FIG. 4 is a block diagram of an example modulation signal generation module that can be used as the modulation signal generation module of the example motor control circuit of FIG. 1;
FIGS. 5 and 5A are block diagrams illustrating exemplary half-bridge output stages of the exemplary motor control circuit of FIG. 1 and showing the direction of motor winding current at different phases of operation;
FIG. 6 is a graph showing waveforms associated with motor windings, specifically with sinusoidal current, modulation waveforms associated with sinusoidal driving of the motor windings, and Pulse Width Modulation (PWM) signals driving the motor according to the modulation waveforms;
FIG. 7 is an visualized diagram showing details of the positive and negative states of the PWM signal of FIG. 6;
FIG. 7A is a graph showing a PWM drive signal applied to a motor and showing sinusoidal currents associated with the PWM drive signal;
FIG. 8 is a block diagram of another exemplary motor control circuit having a modulation signal generation module and having a current measurement module in the form of a zero current detection module; and
fig. 9 is a graph showing various waveforms according to which zero current in the motor windings can be detected, particularly when trapezoidal drive to the motor is used.
Detailed Description
Before describing the present invention, some of the concepts and terms introduced are explained. As used herein, the term "modulation waveform" is used to describe the envelope or characteristic function of other signals, such as Pulse Width Modulation (PWM) signals.
Referring to fig. 1, an exemplary motor control circuit 102 is coupled to drive a motor 104.
The motor 104 is shown as including three windings 104a, 104b, 104c, each of which is generally depicted as having a respective equivalent circuit of an inductor in series with a resistor and in series with a back EMF voltage source. For example, winding a 104a is shown to include an inductor 130 in series with a resistor 131 and in series with a back EMF voltage source VA 136. The voltage of the back EMF voltage source VA 136 is not directly observable when current is flowing into the associated motor winding, but is directly observable when current through the associated winding is zero.
In general, the voltage across the motor windings (e.g., across winding a 140a) is determined by the following equation:
Voutput A-VGeneral purpose＝VA+IR+LdI/dt，
Wherein:
Voutput AVoltage observed at one end of winding a;
Vgeneral purposeThe voltage at the junction of the windings 104a, 104b, 104 c;
r ═ the resistance value of the resistor 131;
l — the inductance value of inductor 130;
i-the current through the winding; and
VA ═ back EMF voltage
Thus, it can be seen that if the current through winding 104a is zero, then V is zeroOutput AVA, which is the voltage that can be observed.
The motor control circuit 102 includes a speed command generator 107 coupled to receive an external speed command signal 106 from outside the motor control circuit 102. The external speed command signal 106 can be in one of a variety of formats. In general, the external speed command signal 106 indicates the speed of the motor 104 that is requested from outside the motor control circuit 102.
The speed command generator 107 is configured to generate a speed command signal 107 a. A Pulse Width Modulation (PWM) generator 108 is coupled to receive the speed command signal 107a and is configured to generate a PWM signal 108a whose maximum duty cycle is controlled by the speed command signal 107 a. The PWM generator 108 is also coupled to receive the modulation waveforms 146a, 146b, 146c from the modulation signal generation module 146. The PWM signal 108a is generated from the modulated waveforms 146a, 146b, 146c with a modulation characteristic (i.e., a relatively time varying duty cycle). The modulation waveform and associated PWM signal are described more fully below in connection with fig. 6.
The motor control circuit 102 also includes a gate driver circuit 110 coupled to receive the PWM signal 108a and configured to generate PWM gate drive signals 110a, 110b, 110c, 110d, 110e, 110f to drive six transistors 112, 114, 116, 118, 120, 122 arranged in three half-bridge circuits 112/114, 116/118, 120/122. Six transistors 112, 114, 116, 118, 120, 122 operate in saturation to provide three motor drive signals Vout A124, Vout B126, Vout C128, respectively, at nodes 102d, 102C, 102B, respectively.
The motor control circuit 102 can also include a position measurement module 142 that can be coupled to receive the back EMF signal (e.g., it can be coupled to receive one or more of the motor drive signals 124, 126, 128 that include a back EMF signal directly observable over time when the motor windings 104a, 104b, 104c are not driven and the respective winding currents are zero) or a hall element signal from a hall element (not shown). The position measurement module 142 is configured to generate a position reference signal 142a indicative of a rotational reference position of the motor 104.
The motor control circuit 102 can also include a current measurement module 144 that can be coupled to receive one of the motor drive signals 124, 126, 128. The current measurement module 144 is configured to generate a zero current signal 144a that indicates a zero crossing of current through one or more of the motor windings. An example current measurement module is described in more detail below in conjunction with fig. 8.
The modulation signal generation module 146 is coupled to receive the position reference signal 142a and the zero current signal 144 a. The modulation signal generation module 146 is configured to vary the phase of the modulation waveforms 146a, 146b, 146c according to the phase difference between the position reference signal 142a and the zero current signal 144 a. An exemplary modulation signal generation module 146 is described below in conjunction with fig. 4.
The motor control circuit 102 can be coupled to receive the motor voltage VMOT at node 102a, or simply VM, which is applied to the motor through transistors 112, 116, 120 during the time that the upper transistors 112, 116, 120 are turned on. It should be appreciated that there can be a small voltage drop (e.g., 0.1 volts) across the transistors 112, 116, 120 when the transistors 112, 116, 120 are turned on and providing current to the motor 104.
As described above, the motor control circuit 102 is capable of automatically adjusting the timing, i.e., phase, of the drive signals 124, 126, 128 relative to the sensed rotational position of the motor 104.
Referring now to fig. 2, curves 200, 220, 240, and 260 have a horizontal axis with a scale in units of arbitrary units of time. The curves 200, 220, 240 have a vertical axis with a scale in voltage in arbitrary units. Curve 260 has a vertical axis with a scale in units of current in arbitrary units.
In some embodiments of the motor control circuit 102 of fig. 1, the zero-crossings of the back EMF signal 202 can be used by the position measurement module 142 to identify a reference rotational position of the motor 104. It is desirable that the zero crossing of the back EMF signal 202 at time 208 coincide or nearly coincide with zero current through the motor windings on which the back EMF signal 202 is generated. This relationship will result in the most efficient motor operation.
In some embodiments of the motor control circuit 102, the back EMF signal is not used to detect the rotational position of the motor 104. Instead, hall elements are positioned around the motor 104 and when the motor 104 rotates, hall element signals 222, 224, 226 are generated. It will be apparent that the signals 222, 224, 226 represent the rotational position of the motor 104. Typically, it can be seen that there are no transients in the hall element signals 222, 224, 226 that are aligned with the zero crossings of the back EMF signal 202. However, time 208 can be identified by signals 222, 224, 226 as a partial path, e.g., half way, between particular transients of signals 222, 224, 226.
It should be appreciated that the modulation waveform 242 is associated with winding a 104a of fig. 1 and is generally aligned with the back EMF signal 202 associated with the same winding. The other modulation waveforms 244, 246 are associated with the other windings B104B, C104C, respectively, of the motor 104 of fig. 1.
The electrical cycle of the motor 104 can be divided into six states or time periods, 201a, 201b, 201c, 201d, 201e, 201 f.
Referring now to fig. 3, curve 300 has a horizontal axis with a scale in arbitrary units of time. Curve 300 has a vertical axis with a scale in arbitrary units of voltage and current. Curve 320 has a horizontal axis with a scale in units of arbitrary units of time. Curve 320 also includes a vertical axis with a scale in units of voltage in arbitrary units.
In general, the modulation signal generation module 146 of fig. 1 is capable of advancing or retarding the various modulation waveforms 146a, 146b, 146c based on the received rotational position reference signal 142a and zero current signal 144a, which represent the back EMF signal 302 and current signals 304, 306.
For conventional sinusoidal motor drive signals such as those described above in connection with fig. 2 and 3, the zero crossings of the back EMF signal 302 cannot be easily observed and detected for the reasons described above in connection with fig. 1, because each of the motor windings 104a, 104b, 104c is constantly driven. In order to observe the back EMF signal, it is necessary to at least temporarily stop the drive signal to the motor windings. Thus, with a sinusoidal motor drive signal arrangement, in some embodiments, the sinusoidal drive signal to at least one of the windings 104a, 104b, 104c of the motor 104 can be stopped within a small time window in order to observe zero-crossings of the back EMF signal. To this end, in the motor control circuit 102 of fig. 1, the control signal 142b can be provided to the gate driver 110 by the position measurement module 142.
Referring now to fig. 4, a modulation signal generation module 402 can be used as the modulation signal generation module 146 of fig. 1.
The modulation signal generation module 402 is coupled to receive the detected position reference signal 414 and the detected zero current signal 418. The detected position reference signal 414 can be the same as or similar to the position reference signal 142a of fig. 1. The detected zero-current signal 418 can be the same as or similar to the zero-current signal 144a of fig. 1.
As described above, the detected position reference signal 414 can be generated using a sinusoidal drive waveform in conjunction with zero-crossings of the back EMF signal for a short period of time during which sinusoidal drive to the winding is stopped. In other embodiments, the detected position reference signal 414 can be generated in conjunction with hall elements and associated hall element signals disposed about the motor 104 of fig. 1.
The modulated signal generation module 402 is also coupled to receive a system clock signal 416 having a fixed high frequency.
A so-called "theta ramp generator" 404 is coupled to receive the detected position reference signal 414 and the system clock signal 416. The theta ramp generator 404 is configured to generate an unadjusted theta signal 404a, which can be a digital signal comprising a sequence of values representing a ramp signal that periodically reaches a final value and is reset to zero. The reset time of the ramp signal is fixed relative to a position reference (i.e., a fixed rotational position of the motor 104) that the detected position reference signal 414 indicates.
In operation, the θ ramp generator 404 is able to identify the time period between position references identified by the detected position reference signal 414 as measured by counting several system clock transitions. In other words, the theta ramp generator 404 is able to identify the time (i.e., the transition of several system clock signals 416) to rotate the motor 104 through one electrical rotation. The theta ramp generator 404 can divide the number of transitions of the identified system clock 416 by a fixed scalar (e.g., by 256). Thus, the motor electrical cycle can be divided into 256 sections. Thus, the clock signal 402 can have a frequency that achieves 256 transitions during one electrical cycle of the motor. The clock signal 402 can be generated and used by the ramp generator 404 to generate a ratio at which the ramp value of the unadjusted theta signal 404a is increased and output within the unadjusted theta signal 404 a. Thus, it should be understood that the reset to zero of the zero ramp signal in unadjusted θ signal 404a is accomplished once for each electrical cycle of the motor and can have, for example, 256 steps in the ramp.
Timing/phase error detector 410 is coupled to receive detected zero current signal 418, coupled to receive detected position reference signal 414, and coupled to receive clock signal 402.
The timing/phase error detector 410 is configured to identify a time difference (i.e., a phase difference) between a position reference identified by the detected position reference signal 414 and a zero-current crossing identified by the detected zero-current signal 418.
Referring briefly again to fig. 3, in other words, the timing/phase error detector 410 is operable to identify a time difference between a zero crossing of the current signal 304 or 306 and a zero crossing of the back EMF voltage signal 302.
Referring again to fig. 4, the timing/phase error detector 410 is configured to generate an error signal 410a, which in some embodiments can be a digital value representing the identified time (i.e., phase) difference.
A proportional-integral-differentiator (PID), or in other embodiments, a proportional-integrator (PI), can be coupled to receive the error signal 410a and configured to substantially filter the error signal 410a to generate an adjustment signal 412 a. In some embodiments, adjustment signal 412a can be a digital value proportional to the time difference identified by timing/phase error detector 410.
The summing module 406 is coupled to receive the unadjusted theta signal 404a (i.e., a set of consecutive digital values representing the reset ramp signal at a fixed phase), is coupled to receive the adjustment signal 412a, and is configured to generate the theta signal 406 a.
In operation, it should be understood that the θ signal 406a is a reset ramp signal like the unadjusted θ signal 404a, but for which the reset time of the ramp signal is shifted in time (i.e., in adjusted phase) according to the value of the adjustment signal 412 a.
The modulation information look-up table and processor 408 are coupled to receive the theta signal 406 a. The modulation information look-up table and processor 408 is configured to store therein values representing one or more modulation information, such as modulation information 242 of fig. 2.
In operation, the θ signal 406a is used to sort between the modulation information look-up table and the values of the modulation signal stored within the processor 408. It should be appreciated that the phase of the theta signal 406a, represented by the reset portion of the theta signal 406a, is adjustable according to the time difference between the position reference identified in the detected position reference signal 414a and the zero crossing of the current in the motor windings as identified within the detected zero crossing signal 418. Thus, the phase (i.e., timing) of the modulated signal 408a generated by the modulation information look-up table and the processor 408 is adjustable.
The modulation information look-up table and processor portion of the processor 408 can automatically generate other modulation information 408b, 408c, such as modulation information 244, 246 of fig. 2, at other fixed phases, which can be at fixed phases relative to the modulation information 408a (such as modulation information 242 of fig. 2).
Exemplary circuits and methods for detecting zero current through the motor windings are described below in conjunction with fig. 5-8. However, it should be understood that other methods can be used to detect zero current through the motor windings.
Referring now to fig. 5, the three half- bridge circuits 502, 504, 506 correspond to the three half-bridge circuits 112/114, 116/118, 120/122 of fig. 1 and are shown driving three motor windings. The current through the half-bridge circuit 502 and through one of the motor windings is indicated by the dashed line identified by the circled numbers 1, 2, and 3. Currents 1, 2, and 3 indicate the current through the half-bridge circuit 502 at different times during the positive pole of the current signal for the motor windings (e.g., during the positive portion of the current signal 262 of fig. 2). Current 1 indicates the upper FET is on, current 3 indicates the lower FET is on, and current 2 indicates both FETs are off. It will be appreciated that current 2 passes through the intrinsic diode of the lower FET and thus, when both FETs of half bridge 502 are off, voltage VOutput A(see, e.g., signal 124 of fig. 1) achieves a voltage of about 0.7 volts below the ground voltage start, and returns to ground when the lower FET turns on. Thus, it should be understood that by detecting the voltage VOutput ABelow the ground voltage and the return ground voltage, an actual zero current through the half bridge 502 and through the associated motor winding can be identified.
Referring now to fig. 5A, in which like elements of fig. 5 are shown with like reference numerals, the current through the half-bridge circuit 502 and through one of the motor windings is still indicated by the dashed lines identified by the circled numbers 1, 2, and 3. Currents 1, 2, and 3 indicate the current through the half-bridge circuit 502 at different times during the negative pole of the current signal for the motor windings (e.g., during the negative pole portion of the current signal 262 of fig. 2). Current 1 indicates the upper FET is on, current 3 indicates the lower FET is on, and current 2 indicates both FETs are off. It will be appreciated that current 2 passes through the intrinsic diode of the upper FET and thus, when both FETs of half bridge 502 are off, the voltage VOutput AA voltage of about 0.7 volts above the voltage VM start is achieved and the voltage VM is returned when the upper FET is turned on. Thus, it should be understood that by detecting the voltage VOutput AAbove the voltage VM and the return voltage VM, the actual zero current through the half bridge 502 and through the associated motor winding can be identified.
Referring now to fig. 6, a graph 600 has a horizontal axis with a scale in arbitrary units of time and a vertical axis with a scale in arbitrary units of current. Curve 620 has a horizontal axis with a scale in units of arbitrary units of time and a vertical axis with a scale in units of arbitrary units of voltage. Curve 640 has a horizontal axis with a scale in units of arbitrary units of time and a vertical axis with a scale in units of arbitrary units of voltage.
The modulated signal 622 can be the same as or similar to modulated signal 242 of fig. 2. The modulated signal 622 can have 6 time periods or phases, four of which are shown as 604a, 604b, 604c, 604 d.
The PWM signal 642 can be generated from the modulated waveform 622 and can have times of high duty cycles 642a, 642b at times of peaks 622a, 622b of the modulated waveform 622 and times of lower duty cycles at times of other portions of the modulated waveform 622, depending on the value of the modulated waveform 622. The PWM signal 642 can be a signal actually applied to the motor winding a 104a of the motor 104 of fig. 1 for sinusoidal driving.
Referring now to fig. 7, the PWM pulses 702, 702' indicate the PWM pulse 642 of fig. 6 during the negative portion of the current signal 602. PWM pulse 704 indicates PWM pulse 642 of fig. 6 during the positive portion of current signal 602.
The PWM pulses 702, 702 'have risen during transient portions 702b, 702c, 702 b', 702c 'and steady- state portions 702a, 702 a'. From the above discussion in connection with fig. 5 and 5A, it will be appreciated that when both transistors (e.g., FETs) of a half bridge are turned off, the voltage V appearing across the associated motor windingOutput AMomentarily above the motor voltage VM, or below ground, depending on the polarity of the current in the motor windings, i.e., the polarity of the current signal 602. It should also be appreciated that each main edge transition of the PWM signals 702, 704, 702' is preceded by a short period of time during which both FETs are turned off, otherwise both FETs may be turned on simultaneously, resulting in a short circuit between the motor voltage VM and ground. Thus, when both FETs are turned off, transient signal portions 702b, 702c, 704b, 704c, 702b ', 702 c' are generated. The transient signal portions 702b, 702c, 704b, 704c, 702b ', 702 c' can occur within a short period of time, such as about 500 nanoseconds.
It is apparent that the direction of the transient voltage signal portions 702b, 702c, 704b, 704c, 702b ', 702 c' changes direction at each occurrence of a zero-crossing of the current signal 602 (i.e., at times 606, 608). Thus, detection of a change in direction of the transient signal portion 702b, 702c, 704b, 704c, 702b ', 702 c' can be used to identify a zero current in the associated motor winding.
Referring now to fig. 7A, curve 720 has a horizontal axis with a scale in arbitrary units of time and a vertical axis with a scale in arbitrary units of voltage. Curve 740 has a horizontal axis with a scale in units of arbitrary units of time and a vertical axis with a scale in units of arbitrary units of current.
The signal 722 is representative of the PWM signal 642 of fig. 6, but shows transient signal portions similar to the transient portions 702b, 702c, 704b, 704c, 702b ', 702 c' of fig. 7. The signal 742 is the same as or similar to the current signal 602 of fig. 1.
Times t1-t9 occur during the transient signal portion. As is apparent from the above discussion in conjunction with fig. 5 and 5A, the transient signal portion occurs when both FETs of the associated half-bridge circuit driving the motor windings are turned off.
For the reasons described above in connection with fig. 5, 5A and 7, at time t6 the transient signal portion changes orientation in line or nearly in line with the zero crossing of the current signal 742. Thus, the change in orientation of the transient signal portion can be used to detect a zero current crossover in the motor windings. In particular, at times t1-t5, the transient signal portion extends above the motor voltage VM. Conversely, at time t6-t9, the transient signal portion extends below ground. Another change or orientation (not shown) of the transient signal portion occurs at the next zero crossing of the current signal 742 and can also be used to detect the next zero crossing.
In some embodiments, the circuitry (see, e.g., comparators 808, 810 shown in fig. 8 below) can be for the signal V Output A722 are sampled to detect transient portions of the signal only at or near times t1-t9 and also at other similar times thereafter. The times t1-t9 and subsequent similar times are known because both FETs are momentarily turned off at those times. In other embodiments, signal 722 can be sampled continuously to detect transientsA state signal portion.
In some embodiments, the change in orientation of the transient signal portion can be detected using two comparators. Two zero crossings of the current signal 742 can be detected. However, in other embodiments, one comparator can be used to detect the presence or absence of an upwardly extending or downwardly extending transient signal portion. Two zero crossings of the current signal 742 can still be detected with one comparator.
Referring now to fig. 8, where elements that are the same as in fig. 1 are shown with the same reference numbers, the zero current detection module 802 can be the same as or similar to the current measurement module 144 of fig. 1.
The zero current detection module 802 can include a first comparator 808 coupled to the three motor windings via a selectable switch 804. The zero current detection module 802 can also include a second comparator 810 coupled to the three motor windings via a selectable switch 806. The first comparator 808 can be coupled to receive a reference voltage that is equal to or close to the motor voltage VM. The second comparator 810 can be coupled to receive a reference voltage at or near ground.
The first comparator 808 is configured to generate an output signal 808a, the output signal 808a being indicative of the voltage on the selected motor winding that exceeds the motor voltage. The second comparator 810 is configured to generate an output signal 810a, the output signal 810a indicating a voltage on the selected motor winding that is below ground. Thus, in operation, the first comparator 808 is operable to detect the positive transient signal portions 702b, 702c, 704b, 704c, 702b ', 702 c' of the PWM signal of fig. 7 associated with sinusoidal motor drive. Also, in operation, the second comparator 810 is operable to detect the negative transient signal portions 704b, 704c of the PWM signal of fig. 7 associated with sinusoidal motor drive. As described above, the edges of these signal portions can be used to identify zero current crossings in the associated motor windings.
The zero current detection module 802 can also include a multiplexer 812, the multiplexer 812 being coupled to receive the output signals 808a, 810a and configured to generate and output a signal 812a representative of a selected one of the output signals 808a, 801 a.
The multiplexer 812 can be coupled to receive the control signal 146d from the modulation signal generation module 146. The switches 804, 806 can be coupled to receive other control signals (not shown) from the modulation signal generation module 146.
The modulation signal generation module 146 can use various types of logic to identify zero current crossings in one or more motor windings. For example, for a PWM sinusoidal motor drive signal, the output signals 808a, 810a can be used to identify changes in direction of the transient signal portions 702b, 702c, 704b, 704c, 702b ', 702 c' of the PWM signal 642, as discussed above in connection with fig. 7 and 7A. Essentially, the multiplexer 812 can switch to look at the other comparators whenever a detection consists of a particular direction of the transient signal portion.
In some embodiments, no switches are used and only one motor winding is used to provide signals to the comparators 808, 810. In some embodiments, only one comparator is used, and multiplexer 812 is not necessary. When the voltage across the motor windings exceeds the motor voltage VM and/or is below ground, various different types of logic can be used by the modulation signal generation module 146 to identify the zero crossing of the current through the motor windings by using the detection techniques described above.
Referring now to fig. 9, curve 900 has a horizontal axis with a scale in arbitrary units of time. Curve 900 also has a vertical axis with a scale in units of arbitrary unit current. Curve 920 has a horizontal axis with a scale in arbitrary units of time. Curve 920 also has a vertical axis with a scale in arbitrary units of voltage.
It should be understood that the voltage waveform 922 represents the actual voltage applied to the motor windings for a one hundred percent motor drive. For one hundred percent motor drive, signal 922 achieves a voltage VM (motor voltage) with one hundred percent duty cycle, and is zero at other times. For a different trapezoidal motor drive (not shown) that is less than one hundred percent, during the time period in which one hundred percent drive signal 922 achieves voltage VM, the different trapezoidal motor drive provides a pulse width modulated signal having a pulse width modulation with a duty cycle according to the motor drive that is less than one hundred percent.
The time of the motor's electrical cycle can be broken down into six states, only four states 902a, 902b, 902c, 902d being shown. The signals during the other two states will be apparent. Each of the motor windings receives a motor drive signal like motor drive signal 922, but shifted in phase and starting at a different one of the phases.
With trapezoidal drive, the drive signal applied to the motor windings is zero during the first phase 902a and also zero during the fourth phase 902 d. Thus, during the first phase 902a and the fourth phase 902d, the current signal 904 achieves zero current during the signal portion 904a and during the signal portion 904 d. Due to the inductive properties of the motor windings, zero current is not immediately realized at the beginning of the first phase 902a and the fourth phase 902 d. For the reasons described above in connection with fig. 1, the back EMF voltage is directly observable across the winding when the drive voltage applied to the winding is zero and the current decays to zero.
For the reasons described more fully above in connection with fig. 5 and 5A, signal 922 on the motor winding achieves a voltage VM + Vd during signal portion 922a, and signal 922 achieves a voltage-Vd during signal portion 922 d. Exemplary methods of detecting zero current during signal portions 904a, 904d are described above in connection with fig. 5 and 5A. To this end, portions 922a, 922d of signal 922 can be used to detect zero winding current using circuits and techniques such as those described above in connection with fig. 5, 5A, and 8.
The back EMF voltage is directly observable during the first phase 902a and the fourth phase 904d portions, particularly during the dashed portions 922b, 922e of the voltage signal 922. During portions 922b, 922e of the voltage signal 922, and during portions 922a, 922d, no drive signal is applied to the associated motor. As described above, the inductive behavior of the motor windings causes current to flow through the motor windings to achieve zero current only during portions 922b, 922e of the drive signal 922.
From the foregoing, it should be apparent that with trapezoidal drive and using six motor drive states, there are a significant number of periods of time in which each motor winding is not driven, e.g., during a period associated with signal portions 922a, 922b collectively occupying one sixth (i.e., 60 degrees) of motor electrical rotation, and during a period associated with signal portions 922d, 922e collectively occupying another one sixth (i.e., 60 degrees) of motor electrical rotation, the motor windings are undriven. The current through the motor windings becomes zero at the end of the transient signal portions 922a, 922d (i.e., during signal portions 922b, 922 e). During the signal portions 922b, 922e, the back EMF voltage is directly observable. Thus, unlike the sinusoidal drive already described above, with a six-state trapezoidal drive arrangement for the motor windings being driven continuously, there is no need to separately generate a time window during which no motor drive is applied to the windings for the purpose of detecting the transient signal portions 922a, 922d that end indicating zero winding current, or for the purpose of detecting zero crossings during the signal portions 922b, 922e that indicate the rotational position of the motor.
All references cited herein are hereby incorporated by reference in their entirety.
Having described preferred embodiments for illustrating the various concepts, structures and techniques that are the subject of this patent, it will now become apparent to those of ordinary skill in the art that other embodiments incorporating these concepts, structures and techniques may be used. Therefore, it is submitted that the scope of the patent should not be limited by the described embodiments but rather should be limited only by the spirit and scope of the appended claims.
Claims (12)
1. A method of driving a multi-phase motor having a plurality of motor windings, the method comprising:
generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings;
generating a position reference signal indicative of a reference position of angular rotation of the motor;
comparing a phase of the zero-current signal with a phase of the position reference signal to generate a phase comparison signal;
generating a plurality of modulated signals, each modulated signal having a phase related to a value of the phase comparison signal; and
generating a plurality of motor drive signals to the plurality of motor windings from the plurality of modulation signals, wherein generating the zero current signal comprises:
generating the plurality of motor drive signals with a respective plurality of half-bridge circuits coupled to the motor, each half-bridge circuit comprising:
a respective first transistor and second transistor coupled in series;
a respective power supply high voltage node for receiving a high power supply voltage, wherein the high power supply voltage is a motor voltage;
a respective power supply low voltage node for receiving a low power supply voltage, wherein the low power supply voltage is a ground voltage; and
a respective output node at which a respective one of the plurality of motor drive signals is generated;
detecting a reverse current through at least one of the first transistor or the second transistor of at least one of the plurality of half-bridge circuits, wherein the detecting comprises at least one of:
detecting a voltage at the output node that is higher than the high supply voltage; or
Detecting a voltage at the output node that is lower than the low supply voltage; and is
Wherein the method further comprises:
generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings based on detecting the reverse current,
wherein generating the plurality of modulated signals comprises:
providing a look-up table in which modulation values corresponding to a shape of at least one of the plurality of modulation signals are stored;
generating a first continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value;
adding a value related to the phase comparison signal to the first continuous sawtooth ramp signal to generate a second continuous sawtooth ramp signal having the minimum value and the maximum value and the plurality of values between the minimum value and the maximum value, wherein the minimum value and the maximum value of the second continuous sawtooth ramp signal are offset in time from the minimum value and the maximum value of the first continuous sawtooth ramp signal by an adjustment time, wherein the adjustment time is related to the phase comparison signal;
sequentially looking up values in the look-up table using the adjusted continuous sawtooth ramp signal to generate the at least one of the plurality of modulation signals; and
generating at least one other modulation signal having a predetermined phase relationship with the at least one of the plurality of modulation signals.
2. The method of claim 1, wherein generating the position reference signal comprises:
generating a Hall sensor signal with a Hall sensor disposed proximate to the motor.
3. The method of claim 1, wherein generating the position reference signal comprises:
generating a back EMF signal with a back EMF module coupled to at least one of the plurality of motor windings.
4. The method of claim 1, wherein generating the position reference signal comprises:
stopping the motor drive signal to at least one of the plurality of motor windings during a time window proximate the motor reaching the reference position; and
detecting the reference position during the time window by a zero crossing of a back EMF signal.
5. The method of claim 1, wherein detecting the reverse current comprises:
detecting the reverse current by sampling a voltage at the output node only over time when both the first transistor and the second transistor are off.
6. The method of claim 1, wherein each of the plurality of motor drive signals comprises:
a respective plurality of pulse width modulated signals, each of the plurality of pulse width modulated signals having a high state comprising a steady state high value proximate to the high supply voltage and a transient high value above the high supply voltage, and each of the plurality of pulse width modulated signals also having a low state comprising a steady state low value proximate to the low supply voltage and a transient low value below the low supply voltage.
7. An electronic circuit for driving a multi-phase motor having a plurality of motor windings, the electronic circuit comprising:
a current measurement module configured to generate a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings;
a position measurement module configured to generate a position reference signal indicative of a reference position of angular rotation of the motor;
a modulation signal generation module configured to compare a phase of the zero-current signal with a phase of the position reference signal to generate a phase comparison signal and configured to generate a plurality of modulation signals each having a phase related to a value of the phase comparison signal; and
a drive circuit configured to generate a plurality of motor drive signals to the plurality of motor windings from the plurality of modulation signals,
a plurality of half-bridge circuits coupled to the motor and configured to generate the plurality of motor drive signals, each half-bridge circuit comprising:
a respective first transistor and second transistor coupled in series;
a respective power supply high voltage node for receiving a high power supply voltage, wherein the high power supply voltage is a motor voltage;
a respective power supply low voltage node for receiving a low power supply voltage, wherein the low power supply voltage is a ground voltage; and
a respective output node at which a respective one of the plurality of motor drive signals is generated,
the electronic circuit further comprises:
at least one comparator configured to generate a respective at least one comparator output signal indicative of a reverse current through at least one of the first or second transistors of at least one of the plurality of half-bridge circuits by detecting at least one of:
a voltage at the output node that is higher than the high supply voltage; or
A voltage at the output node that is lower than the low supply voltage, and the electronic circuit further comprises:
a processor configured to generate the zero current signal indicative of the zero crossing of the current through the at least one of the plurality of motor windings as a function of the at least one comparator output signal,
wherein the modulation signal generation module comprises:
a look-up table in which modulation values corresponding to a shape of at least one of the plurality of modulation signals are stored;
a sawtooth generator configured to generate a first continuous sawtooth ramp signal having a minimum value and a maximum value and a plurality of values between the minimum value and the maximum value;
a timing/phase error detector coupled to receive a signal representative of the zero current signal, coupled to receive a signal representative of the position reference signal, and configured to generate a signal representative of the phase comparison signal; and
a summing module configured to add a value related to the phase comparison signal to the first continuous sawtooth ramp signal, to generate a second continuous sawtooth ramp signal having the minimum value and the maximum value and a plurality of values between the minimum value and the maximum value, wherein the minimum value and the maximum value of the second continuous sawtooth ramp signal are offset in time from the minimum value and the maximum value of the first continuous sawtooth ramp signal by an adjustment time, wherein the adjustment time is related to the phase comparison signal, wherein the adjusted continuous sawtooth ramp signal is used to sequentially look up values in the look-up table to generate the at least one of the plurality of modulation signals, and further for generating at least one other modulation signal having a predetermined phase relationship with said at least one of said plurality of modulation signals.
8. The electronic circuit of claim 7, wherein the position measurement module is further configured to generate the position reference signal as a function of a Hall signal generated by a Hall sensor disposed proximate to the motor.
9. The electronic circuit of claim 7, wherein the position measurement module is further configured to generate the position reference signal from a back EMF signal generated in a motor winding.
10. The electronic circuit of claim 7, wherein generating the position reference signal comprises:
stopping the motor drive signal to at least one of the plurality of motor windings during a time window proximate the motor reaching the reference position; and
detecting the reference position during the time window by a zero crossing of a back EMF signal.
11. The electronic circuit of claim 7, wherein the detecting comprises:
the reverse current is detected by sampling a voltage at the output node only at times when both the first and second transistors are off.
12. The electronic circuit of claim 7, each of the plurality of motor drive signals comprising:
a respective plurality of pulse width modulated signals, each of the plurality of pulse width modulated signals having a high state comprising a steady state high value proximate to the high supply voltage and a transient high value above the high supply voltage, and each of the plurality of pulse width modulated signals further having a low state comprising a steady state low value proximate to the low supply voltage and a transient low value below the low supply voltage.
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| US13/599,225 | 2012-08-30 | ||
| US13/599,234 US8917044B2 (en) | 2012-08-30 | 2012-08-30 | Electronic circuit and method for detecting a zero current in a winding of an electric motor |
| US13/599,225 US8917043B2 (en) | 2012-08-30 | 2012-08-30 | Electronic circuit and method for automatically adjusting a phase of a drive signal applied to an electric motor in accordance with a zero current detected in a winding of the electric motor |
| CN201380056237.5A CN104756395B (en) | 2012-08-30 | 2013-08-13 | The phase of the drive signal applied for the zero current adjust automatically detected in the winding according to motor to motor and electronic circuit and method for detecting zero current |
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| CN201710841680.3A Active CN107565857B (en) | 2012-08-30 | 2013-08-13 | Electronic circuit and method for driving a polyphase electric motor having a plurality of motor windings |
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| KR102520720B1 (en) * | 2015-11-30 | 2023-05-02 | 삼성전자주식회사 | Device and control method for driving sensorless bldc motor |
| US10312847B2 (en) * | 2016-05-09 | 2019-06-04 | Allegro Microsystems, Llc | Motor control using phase current and phase voltage |
| US11315539B2 (en) * | 2017-09-27 | 2022-04-26 | Honda Motor Co., Ltd. | Active vibration noise control system |
| US11362605B2 (en) | 2020-01-29 | 2022-06-14 | Semiconductor Components Industries, Llc | Drive methods for a three-phase motor |
| TWI775538B (en) * | 2021-07-21 | 2022-08-21 | 茂達電子股份有限公司 | Motor controlling circuit having voltage detection mechanism |
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| TW201429149A (en) | 2014-07-16 |
| KR102159616B1 (en) | 2020-09-24 |
| JP2015527050A (en) | 2015-09-10 |
| KR20150048845A (en) | 2015-05-07 |
| CN104756395B (en) | 2018-02-02 |
| TWI500253B (en) | 2015-09-11 |
| CN104756395A (en) | 2015-07-01 |
| KR102139948B1 (en) | 2020-07-31 |
| JP6429777B2 (en) | 2018-11-28 |
| WO2014035658A3 (en) | 2015-03-26 |
| KR20200010600A (en) | 2020-01-30 |
| WO2014035658A2 (en) | 2014-03-06 |
| CN107565857A (en) | 2018-01-09 |
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