KR20200010600A - 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 and for detecting the zero current - Google Patents

Abstract

Motor control circuitry and related technologies can adjust the phase of the motor drive to maintain the rotational reference position of the electric motor in the same relative phase as zero current in the motor windings at different motor speeds as the motor is accelerated or decelerated. Motor control circuitry and related technologies detect zero crossings of current in the motor windings by detecting the reverse current in the half bridge circuit used to drive the motor windings.

Description

ELECTRICAL 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 AND FOR DETECTING THE ZERO CURRENT}

The present invention relates generally to electric motor control circuits, and more particularly, to provide automatic adjustment of the phase of a drive signal applied to an electric motor and to detect zero current in the windings of the electric motor. It relates to an electric motor control circuit that can.

Circuits for controlling and driving brushless DC (BLDC) electric motors are known. In some devices, the circuits provide a phase progression of drive signals for driving the electric motor, the phase progression being related to the rotational speed of the electric motor or to the measured motor total current. However, these circuits may provide only one relationship between phase advances and rotation speeds, or may provide a small number of relationships. In addition, external components and pins of the motor control integrated circuit (IC) may be required to set parameters for each electric motor or for each electric motor application.

Some known electric motor drive circuits are disclosed in US Patent No. 7,590,334, filed September 15, 2009, US Patent No. 7,747,146, filed June 29, 2010, and US patent application, filed October 12, 2011. 13 / 271,723, all of which are hereby incorporated by reference and are assigned to the assignee of the present application.

BLDC electric motors may exhibit different efficiency behaviors for speed when used in other applications. For example, the same BLDC electric motor can be used with other fan vane devices in different applications. Other types of BLDC electric motors can also exhibit different efficiency behaviors for speed.

Motor noise, vibration and efficiency are affected by various characteristics. One such property is the phase of the currents present in the motor windings relative to the rotational position of the motor. In particular, as the motor speed increases or decreases, the phases of the currents can each lag behind or precede the reference rotational position of the motor. Also, at high motor speeds, current in the motor windings may tend to lag behind the reference position of the motor.

In view of the foregoing, it may be desirable to provide an electric motor control circuit and associated method capable of generating electric motor drive signals with automatic phase adjustments determined in accordance with the detected phase difference between the motor winding current and the motor rotational position. have.

In addition, in view of the foregoing, it may be desirable to provide an electric motor control circuit and associated method capable of detecting the phase of the current in the motor winding, for example by detecting the zero crossing of the current.

The present invention provides an electric motor control circuit and associated method capable of generating electric motor drive signals with automatic phase adjustments determined in accordance with the detected phase difference between the motor winding current and the motor rotational position.

The present invention also provides an electric motor control circuit and associated method capable of detecting the phase of the current in the motor winding, for example by detecting the zero crossing of the current.

According to one aspect of the present invention, a method of driving a multi-phase motor having a plurality of motor windings includes a zero current representing a zero crossing of current through at least one of the plurality of motor windings. generating a zero current signal; Generating a position reference signal indicative of a reference position of an angular rotation of the motor; Comparing a phase of the zero current signal and a phase of the position reference signal to generate a phase comparison signal; Generating a plurality of modulated signals, each having a phase related to a value of the phase comparison signal; And generating a plurality of motor drive signals for the plurality of motor windings in accordance with the plurality of modulation signals.

In some embodiments, the method described above can include one or more of the following aspects.

In some embodiments of the method, generating the position reference signal includes:

Generating a hall sensor signal with a Hall sensor disposed proximate to the motor.

In some embodiments of the method, generating the position reference signal includes:

Generating a back EMF signal to 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 includes:

Stopping a motor drive signal for at least one of the plurality of motor windings during a time window proximate the motor embodying the reference position; And

Detecting the reference position during the time window by 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 are stored corresponding to at least one shape of the plurality of modulation signals;

Generating a first continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;

Converting the first continuous sawtooth ramp signal to a second continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value; Adding to a value associated with s i, wherein the smallest and largest values of the second consecutive sawtooth ramp signal are adjusted times from the smallest and largest values of the first continuous sawtooth ramp signal. Shifted in time by the adjustment time being related to the phase comparison signal;

Using the adjusted continuous sawtooth ramp signals to continuously find values in the lookup table to generate at least one of the plurality of modulated signals;

Generating at least one other modulated signal in a predetermined phase relationship with at least one of the plurality of modulated signals.

In some embodiments of the method, generating the zero current signal comprises:

Generating the plurality of motor drive signals with respective plurality of half bridge circuits coupled to the electric motor, wherein each half bridge circuit comprises:

Respective first and second series connected transistors;

Each power supply high voltage node for receiving a high power supply voltage;

Each power supply low voltage node for receiving a low power supply voltage; And

Each output node on which one of each of the plurality of motor drive signals is generated;

Detecting a reverse current passing through at least one of the first or second transistors of at least one of the plurality of half bridge circuits, wherein the detecting comprises:

Detecting a voltage at the output node above the high power supply voltage; or

Detecting a voltage at the output node below the low power supply voltage,

Generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings in accordance with detecting the reverse current.

In some embodiments of the method, detecting the reverse current comprises:

Detecting the reverse current by sampling a voltage only at the output node at times when both the first and second transistors are turned off.

In some embodiments of the method, each one of the plurality of motor drive signals,

Each of the plurality of pulse width modulated signals, each one of the plurality of pulse width modulated signals having steady state high values proximate the high power supply voltage and transient high values higher than the high power supply voltage. High states, each one of the plurality of pulse width modulation signals also has low states having steady state low values proximate the low power supply voltage and transient low values lower than the low power supply voltage.

According to another aspect of the present invention, an electronic circuit for driving a multiphase motor having a plurality of motor windings is configured to generate a current measurement signal that is configured to generate a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings. Contains modules The electronic circuit also includes a position measuring module configured to generate a position reference signal indicative of the reference position of each rotation of the motor. The electronic circuit is further configured to compare the phase of the zero current signal and the phase of the position reference signal to generate a phase comparison signal, each generating a plurality of modulated signals having a phase related to the value of the phase comparison signal. And a modulated signal generation module configured to. The electronic circuit also includes a drive circuit configured to generate a plurality of motor drive signals for the plurality of motor windings in accordance with the plurality of modulation signals.

In some embodiments, the foregoing electronic circuit can include one or more of the following aspects.

In some embodiments of the electronic circuit, the position measuring module is further configured to generate the position signal in accordance with a Hall signal generated by a Hall sensor disposed in proximity to the motor.

In some embodiments of the electronic circuit, the position measuring module is further configured to generate the position signal in accordance with a back EMF signal generated in a motor winding.

In some embodiments of the electronic circuit, generating the position reference signal includes:

Stopping a motor drive signal for at least one of the plurality of motor windings during a time window proximate the motor embodying the reference position; And

Detecting the reference position during the time window by zero crossing of the back EMF signal.

In some embodiments of the electronic circuit, the modulated signal generation module,

A look up table storing modulation values corresponding to at least one shape of the plurality of modulation signals;

A tooth generator configured to generate a first continuous tooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;

A timing / phase error detector coupled to receive a signal indicative of the zero current signal, coupled to receive a signal indicative of the position reference signal, and configured to generate a signal indicative of the phase comparison signal ); And

The first continuous to a value associated with the phase comparison signal to generate a second continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value. And a summation module configured to add the sawtooth ramp signal, wherein the smallest and largest values of the second consecutive sawtooth ramp signal are the smallest and largest of the first continuous sawtooth ramp signal. Shifted in time by an adjustment time from values, the adjustment time being associated with the phase comparison signal, wherein the adjusted continuous sawtooth ramp signal is generated in the lookup table to generate at least one of the plurality of modulation signals. Used to sequentially find the values and write down in a predetermined phase relationship to at least one of the plurality of modulated signals Fig. 1 is used to generate another modulated signal.

In some embodiments, the electronic circuitry,

A plurality of half bridge circuits coupled to the electric motor and configured to generate the plurality of motor drive signals, each half bridge circuit comprising:

Respective first and second directly connected transistors;

Each power supply high voltage node for receiving a high power supply voltage;

Each power supply low voltage node for receiving a low power supply voltage; And

Each output node on which one of each of the plurality of motor drive signals is generated,

Further comprising at least one comparator, wherein the comparator,

A voltage at the output node that is above the high power supply voltage; or

At least each of which represents a reverse current through at least one of the first and second transistors of at least one of the plurality of half bridge circuits by detecting at least one of the voltages at the output node that is less than or equal to the low power supply voltage. Generate one comparator output signal;

And a processor configured to generate the zero current signal indicative of the zero crossing of the current through at least one of the plurality of motor windings in accordance with the at least one comparator output signal.

In some embodiments of the electronic circuit, the detecting further includes detecting the reverse current by sampling a voltage at the output node only at times when both the first and second transistors are turned off. do.

In some embodiments of the electronic circuit, each one of the plurality of motor drive signals is:

A respective one of each of the plurality of pulse width modulated signals, each one of the plurality of pulse width modulated signals having a steady state high values proximate the high power supply voltage and a transient high values higher than the high power supply voltage. Each of the plurality of pulse width modulated signals also has low states having steady state low values proximate the low power supply voltage and transient low values lower than the low power supply voltage.

According to another aspect of the invention, a method for driving a polyphase motor having a plurality of motor windings comprises generating a motor drive signal with a half bridge circuit connected to the electric motor. The half bridge circuit includes first and second transistors connected 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 from which the motor drive signal is generated. The method also includes detecting a reverse current through at least one of the first and second transistors. The detecting may include detecting a voltage at the output node that is greater than or equal to the high power supply voltage; Or detecting a voltage at the output node that is less than or equal to the low power 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 in accordance with detecting the reverse current.

In some embodiments, the method described above can include one or more of the following features.

In some embodiments of the method, detecting the reverse current comprises:

Detecting the reverse current by sampling a voltage at the output node only at times when both the first and second transistors are turned off.

In some embodiments of the method, the motor drive signal,

A high state comprising a plurality of pulse width modulated signals, each one of said plurality of pulse width modulated signals having steady state high values proximate said high power supply voltage and transient high values higher than said high power supply voltage; Each one of the plurality of pulse width modulated signals also has low states with steady state low values proximate the low power supply voltage and transient low values lower than the low power supply voltage.

In some embodiments, the method,

Generating a position reference signal indicative of a reference position of each rotation of the motor;

Comparing a phase of the zero current signal and a phase of the position reference signal to generate a phase comparison signal;

Generating a plurality of modulated signals, each having a phase associated with a value of the phase comparison signal; And

Generating a plurality of motor drive signals for the plurality of motor windings in accordance with the plurality of modulation signals.

In some embodiments of the method, generating the position reference signal includes:

Generating a hall sensor signal to a hall sensor disposed proximate to the motor.

In some embodiments of the method, generating the position reference signal includes:

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 includes:

Stopping a motor drive signal for at least one of the plurality of motor windings during a time window proximate the motor embodying the reference position; And

Detecting the reference position during the time window by zero crossing of a back EMF signal.

In some embodiments of the method, generating the plurality of modulated signals comprises:

Providing a lookup table in which modulation values are stored corresponding to at least one shape of the plurality of modulation signals;

Generating a first continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;

The first continuous to a value associated with the phase comparison signal to generate a second continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value. Adding a sawtooth ramp signal, wherein the smallest and largest values of the second consecutive sawtooth ramp signal are determined by an adjustment time from the smallest and largest values of the first continuous sawtooth ramp signal; Shifted in time, the adjustment time being related to the phase comparison signal;

Using the adjusted continuous sawtooth ramp signal to continuously find values in the lookup table to generate at least one of the plurality of modulated signals;

Generating at least one other modulated signal in a predetermined phase relationship with at least one of the plurality of modulated signals, each modulated signal associated with each one of the plurality of pulse width modulated (PWM) signals.

According to another aspect of the invention, an electronic circuit for driving a polyphase motor having a plurality of motor windings comprises a half bridge circuit connected to the electric motor to generate a motor drive signal. The half bridge circuit includes first and second transistors connected 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 from which the motor drive signal is generated. The electronic circuit also includes a voltage at the output node that is above the high power supply voltage; Or generate each at least one comparator output signal representing a reverse current through at least one of the first and second transistors by detecting at least one of the voltages at the output node that is less than or equal to the low power supply voltage. At least one comparator configured. The electronic circuit also includes a processor configured to generate a zero current output signal indicative of a zero crossing of current through at least one of the plurality of motor windings in accordance with the at least one comparator output signal.

In some embodiments, the electronic circuit described above can include one or more of the following aspects.

In some embodiments of the electronic circuit, the detecting is:

Detecting the reverse current by sampling the voltage at the output node only at times when both the first and second transistors are turned off.

In some embodiments of the electronic circuit, the motor drive signal,

A high state comprising a plurality of pulse width modulated signals, each one of said plurality of pulse width modulated signals having steady state high values proximate said high power supply voltage and transient high values higher than said high power supply voltage; Each one of the plurality of pulse width modulated signals also has low states with steady state low values proximate the low power supply voltage and transient low values lower than the low power supply voltage.

In some embodiments, the electronic circuitry,

A position measuring module, configured to generate a position reference signal indicating a reference position of each rotation of the motor; And

A modulation signal configured to compare a phase of the zero current signal with a phase of the position reference signal to generate a phase comparison signal, each of which is configured to generate a plurality of modulation signals having a phase associated with a value of the phase comparison signal It further comprises a generation module.

In some embodiments of the electronic circuit, the position measuring module is further configured to generate the position signal in accordance with a hall signal generated by a hall sensor disposed in proximity to the motor.

In some embodiments of the electronic circuit, the position measuring module is further configured to generate the position signal in accordance with a back EMF signal generated in a motor winding.

In some embodiments of the electronic circuit, the electronic circuit is configured to stop a motor drive signal for at least one of the plurality of motor windings during a time window proximate to the motor implementing the reference position. The position measurement module is configured to generate the position reference signal indicative of the reference position during the time window.

In some embodiments of the electronic circuit, the modulated signal generation module,

A lookup table in which modulation values are stored corresponding to at least one shape of the plurality of modulation signals;

A tooth generator configured to generate a first continuous tooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;

A timing / phase error detector configured to receive a signal indicative of the zero current signal, and configured to receive a signal indicative of the position reference signal, and to generate a signal indicative of the phase comparison signal; And

The first continuous to a value associated with the phase comparison signal to generate a second continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value. And an addition module configured to add the sawtooth ramp signal, wherein the smallest and largest values of the second consecutive sawtooth ramp signal are adjusted from the smallest and largest values of the first continuous sawtooth ramp signal. Shifted in time by time, the adjustment time being related to the phase comparison myth, the adjusted continuous sawtooth ramp signal successively summing values in the lookup table to generate at least one of the plurality of modulation signals. At least one in a predetermined phase relationship for at least one of said plurality of modulated signals, Is used to generate a modulated signal, the modulated signal is directed to one or each of the plurality of pulse width modulation (PWM) signal.

In addition to the above-described features of the present invention, the present invention may be understood in more detail from the following detailed description of the drawings, in the accompanying drawings,
1 is a block diagram of an exemplary motor control circuit having a modulating signal generating module and having a current measuring module,
FIG. 2 is a graph showing various waveforms associated with the exemplary motor control circuit of FIG. 1, particularly when the motor control circuit is used to provide sinusoidal drive to the motor, and FIG.
FIG. 3 is a graph showing various waveforms associated with the exemplary motor control circuit of FIG. 1, in particular when the motor control circuit is used to provide sinusoidal shaped driving to the motor, and illustrating the phase differences between the current signal and the position reference signal;
4 is a block diagram of an example modulated signal generation module that may be used as a modulated signal generation module of the example motor control circuit of FIG. 1;
5 and 5A show example half bridge output stages of the example motor control circuit of FIG. 1, are block diagrams illustrating the directions of motor winding current in different phases of operation, and FIG.
6 is a graph showing a pulse width modulation (PWM) signal for driving a motor according to a waveform related to a motor winding, in particular a sinusoidal current, a modulation waveform related to driving a sinusoidal shape of the motor winding, and a modulation waveform;
FIG. 7 is a diagram illustrating details of the positive and negative states of the pulse width modulated (PWM) signal of FIG. 6;
FIG. 7A is a graph showing a pulse width modulation (PWM) driving signal applied to an electric motor, and showing a sinusoidal current related to a pulse width modulation (PWM) driving signal
8 is another exemplary motor control circuit block diagram having a modulating signal generating module and having a current measuring module in the form of a zero current detection module;
9 is a graph showing various waveforms in which zero current in a motor winding can be detected, particularly when trapezoidal drive is used for the motor.

Before describing the invention, some introduction concepts and terms are described. As used herein, the term "modulation waveform" is used to describe the covering or characteristic function of another signal, eg, a pulse width modulated (PWM) signal.

Referring to FIG. 1, an exemplary motor control circuit 102 is connected to drive an electric motor 104.

The motor 104 is shown to include three windings 104a, 104b, 104c, each in series with a resistor and in series with an inductor and back EMF voltage source. It is often shown as each circuit having an inductor. For example, winding A 104a is shown to include an inductor 130 in series with resistor 131 and in series with back EMF voltage source VA 136. The voltage of the back EMF voltage source VA 136 cannot be directly observed when the current flows through the associated motor winding, but can be directly observed when the current through the associated winding is zero.

In general, the voltage across the motor winding, for example the voltage across winding A 140a, is governed by the following equation.

VoutA-Vcommon = VA + IR + LdI / dt

here,

VoutA = observable voltage at one end of the winding A;

Vcommon = voltage at the junction of the windings 104a, 104b, 104c;

R = resistance of the resistor 131;

L = inductance of inductor 130;

I = current through the winding; And

VA = reverse electromotive force voltage.

Thus, if the current through the winding 104a is zero then it can be seen that VoutA = VA, which is the voltage that can be observed.

The motor control circuit 102 includes a speed demand generator 107 coupled to receive an external speed demand signal 106 from outside of the motor control circuit 102. The external speed request signal 106 may be one of various formats. In general, the external speed request signal 106 indicates the speed of the motor 104 that is required from outside of the motor control circuit 102.

The speed request generator 107 is configured to generate a speed request signal 107a. A pulse width modulation (PWM) generator 108 is coupled to receive the speed request signal 107a, the maximum duty cycle of which is controlled by the speed request signal 107a. Configured to generate signals 108a. The pulse width modulation generator 108 is also coupled to receive modulation waveforms 146a, 146b, 146c from modulation signal generation module 146. The pulse lock modulated signals 108a are generated with modulation characteristics (i.e., relative time-varying duty cycles) in accordance with the modulation waveforms 146a, 146b, 146c. The modulation waveforms and associated pulse width modulated signals are described in more detail below in conjunction with FIG. 6.

The motor control circuit 102 is also connected to receive the pulse width modulated signals 108a and arranged as three half bridge circuits 112/114, 116/118, 120/122. Gate driver circuit configured to generate pulse width modulated gate drive signals 110a, 110b, 110c, 110d, 110e, 110f for driving six transistors 112, 114, 116, 118, 120, 122 driver circuit 110). The six transistors 112, 114, 116, 118, 120, 122 each provide three motor drive signals VoutA, VoutB and VoutC 124, 126 and 128 at nodes 102d, 102c and 102b, respectively. Operate in saturation.

The motor control circuit 102 may also include a position measuring module 142, which is not capable of driving back EMF signal (s) (e.g., the motor windings 104a, 104b, 104c). Or a Hall element (which may be coupled to receive one or more of the motor drive signals 124, 126, 128) including back electromotive force signals that can be directly observed at times where each of the winding currents are zero And may be connected to receive Hall element signals from Hall elements (not shown). The position measuring 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 may also include a current measurement module 144, which may be connected 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 representing a zero crossing of current through one or more of the motor windings. An exemplary current measurement module is described in more detail below in conjunction with FIG.

The modulated signal generation module 146 is connected to receive the position reference signal 142a and the zero current signal 144a. The modulation signal generation module 146 is configured to change 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 144a. An exemplary modulated signal generation module 146 is described next in conjunction with FIG.

The motor control circuit 102 may be coupled to receive the motor voltage VMOT or simply the voltage VM at node 102a, during the times when the upper transistors 112, 116, 120 are turned on. The transistors 112, 116, 120 are provided to the motor. It will be appreciated that there may be a small voltage drop (eg, 0.1 volts) through the transistors 112, 116, 120 when they are turned on and supplying current to the motor 104.

As described above, the motor control circuit 102 may automatically adjust the timing, ie phase, of the drive signals 124, 126, 128 associated with the sensed rotational position of the motor 104. .

Referring now to FIG. 2, the graphs 200, 220, 240, 260 have horizontal axes scaled in units of time in arbitrary units. The graphs 200, 220, 240 have vertical axes scaled in units of voltage in arbitrary units. The graph 260 has a vertical axis scaled in units of current in arbitrary units.

Signal 202 represents a back EMF signal (ie, a voltage signal) on motor windings (eg, winding A 104a) of motor 104 of FIG. 1 as the motor 104 rotates. The back EMF voltage 202 is generally sinusoidal.

In some embodiments of the motor control circuit 102 of FIG. 1, the zero crossing of the back EMF signal 202 may be used by the position measurement module 142 to confirm the reference rotational position of the motor 104. Can be. As the back EMF signal 202 is generated, it is desirable that at zero time 208 the zero crossing of the back EMF signal 202 coincides with or nearly coincides with the zero current passing through the motor windings. 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 located relative to the motor 104, and Hall element signals 222, 224, 226 are generated as the motor 104 rotates. It should be apparent that the signals 222, 224, 226 represent the rotational positions of the motor 104. In particular, it can be seen that there are no transients of the Hall element signals 222, 224, and 226 adjusted to the zero crossing of the back EMF signal 202. Nevertheless, the time 208 may be identified by the signals 222, 224, 226 as part between certain transients of the signals 222, 224, 226, for example as intermediate. .

Signals 242, 244, 246 represent the aforementioned modulation waveforms 146a, 146b, 146c of FIG. 1. The modulation waveforms 242, 244, 246 are used to generate pulse width modulated (PWM) signals to drive the motor 104. The relationship between the modulation waveforms 242, 244, 246 and the pulse width modulated signals is described in more detail below in conjunction with FIG. 6.

It will be appreciated that the modulation waveform 242 is associated with winding A 104a of FIG. 1 and aligned with the back EMF signal 202 generally associated with the same winding. Other modulation waveforms 244, 246 are associated with different windings B and C 104b and 104c of the motor 104 of FIG. 1, respectively.

Signals 262, 264, and 266 represent the currents present on the windings A, B, and C 104a, 104b, and 104c, respectively, of the motor 104 of FIG. It will be appreciated that the actual current signals on the motor windings may be more complex than the cases shown in the signals 262, 264, 266. However, the current signals 262, 264, 266 represent the average current over time through the three motor windings. It will be appreciated that the current 262 on the motor winding A 104a is generally in phase with the back EMF signal 202. However, there may be a phase difference between the current signal 262 and the associated back EMF signal 202 as described in more detail below in conjunction with FIG. 3.

The electrical rotation of the motor 104 can be divided into six states or time intervals 201a, 201b, 201c, 201d, 201e, 201f.

Referring now to FIG. 3, graph 300 has a horizontal axis scaled in units of time in arbitrary units. The graph 300 also has a vertical axis scaled in units of voltage in arbitrary units. Graph 320 has a horizontal axis scaled in units of time in arbitrary units. The graph 320 also has a vertical axis scaled in units of voltage in arbitrary units.

Signal 304 represents the current signal on winding A 104a of FIG. Thus, the signal 304 corresponds to the signal 262 of FIG. Signal 302 represents back EMF signal 136 on winding A 104a of FIG. Thus, the signal 302 corresponds to the signal 202 of FIG. The zero crossings of the signals 302 and 304 will be apparent. The time difference 308 represents the time difference between the zero crossing of the back EMF signal 302 and the zero crossing of the current signal 304. Thus, the time difference 308 represents the time difference between the rotational position reference (ie, zero crossing of the back EMF signal 302) and the zero current passing through the associated motor winding.

Signal 306 represents the current signal on winding A 104a of FIG. 1 during the time interval at which the motor 104 accelerates its rotation speed or while the motor 104 rotates at high speed. It can be seen that the relative phases have shifted. The zero crossing of the current signal 306 is delayed with respect to the zero crossing of the back EMF signal 302. The zero crossing of the back EMF signal 302 represents the reference rotational position of the motor 104. The zero crossing of the current signal 306 represents the zero current through the motor winding A 104a. Preferably, the zero crossings occur simultaneously in time and phase. Lack of time co-occurrence will result in increased motor noise and vibration and reduced motor efficiency.

The modulation waveform 322 is the same as or similar to the modulation waveform 242 of FIG. 2. Thus, it can be seen that when the motor accelerates or rotates rapidly, the current signal 306 is delayed with respect to the modulation waveform 322. The modulation waveform 322 is advanced to propagate the current signal 306 (ie, by moving the modulation waveform 322 to the left) so that zero crossings of the current signal 306 are generated by the motor 104. It may be desirable to be able to coincide with or nearly coincide with the zero crossing of the counter electromotive force signal 302 which represents the rotational reference position.

In general, the modulation signal generation module 146 of FIG. 1 is also in accordance with the received rotational position reference signal 142a represented by the back EMF signal 302 and the current signals 304, 306 and the zero current signal. Various modulation waveforms 146a, 146b, 146c may be advanced or delayed according to 144a.

For the conventional sinusoidal motor drive signals as described above in conjunction with FIGS. 2 and 3, for each of the causes described above in conjunction with FIG. 1, each one of the motor windings 104a, 104b, 104c is continuously As it is driven, it is not easy to observe and detect the zero crossing of the back EMF signal 302. In order to observe the counter electromotive force signal, it is necessary to stop the drive signal for at least a brief moment with respect to the motor winding. Thus, with a sinusoidal shaped motor drive signal arrangement, in some embodiments, the sinusoidal shaped drive signal for at least one of the motor windings 104a, 104b, 104c of the motor 104 may result in the inverse electromotive force signal. Can be stopped during a small time window to observe zero crossings. To this end, in the motor control circuit 102 of FIG. 1, a control signal 142b may be provided to the gate driver 110 by the position measuring module 142.

Referring now to FIG. 4, the modulated signal generation module 402 can be used as the modulated signal generation module 146 of FIG. 1.

The modulated 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 may be the same as or similar to the position reference signal 142a of FIG. 1. The detected zero current signal 418 may be the same as or similar to the zero current signal 144a of FIG. 1.

As described above, the detected position reference signal 414 uses zero sine crossings of the back electromotive force signal by using a sinusoidal drive waveform by using a short time interval while the sinusoidal drive with respect to a winding is stopped. Can occur together with the In other embodiments, the detected position reference signal 414 may be generated with Hall elements disposed around the motor 104 and associated Hall element signals 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 may be configured to generate an unadjusted theta signal 404a, which may be a digital signal consisting of a sequence of values representing a ramp signal that periodically reaches an end value and resets to zero. . The reset time of the ramp signal is fixed in relation to the position reference (ie, fixed rotational position of the motor 104) indicated by the detected position reference signal 414.

In operation, the theta ramp generator 404 counts the number of system clock transitions between the position references identified by the detected position reference signal 414 to identify the time interval measured. Can be. In other words, the theta ramp generator 404 can ascertain the time it takes for the motor 104 to rotate through one electrical rotation (ie, the number of transitions in the system clock signal 416). The theta ramp generator 404 may divide the identified number of transitions of the system clock 416 by a fixed number, for example 256. Thus, the motor electrical rotation can be divided into 256 parts. Accordingly, the clock signal 402 may have a frequency that implements 256 transitions, for example, during one electrical rotation of the motor. The clock signal 402 is generated by the theta ramp generator 404 to generate a rate at which ramp values of the unadjusted theta signal 404a increase and an output in the unadjusted theta signal 404a and Can be used. Thus, it will be appreciated that a reset to zero of the ramp signal in the unregulated theta signal 404a may be implemented once during each electrical rotation of the motor, eg, 256 steps may exist in the ramp. .

A timing / phase error detector 410 is coupled to receive the detected zero current signal 418, is coupled to receive the detected position reference signal 414, and the clock signal ( 402 is connected to receive.

The timing / phase error detector 410 determines the time difference (i.e., phase) between the position reference identified by the detected position reference signal 414 and the zero current intersection identified by the detected zero current signal 418. Difference).

Referring briefly to FIG. 3, in other words, the timing / phase error detector 410 identifies the time difference between the zero crossing of the current signal 304 or 306 and the zero crossing of the back EMF signal 302. To operate.

Referring back to FIG. 4, the timing / phase error detector 410 is configured to generate an error signal 410a, which in some embodiments, the identified time (ie, phase). It can be a digital value representing the difference.

A proportional integrator differentiator (PID) or, in other embodiments, a proportional integrator (PI) may be coupled to receive the error signal 410a and generate the error signal (412a) to generate an adjustment signal 412a. 410a) may be configured to filter by default. In some embodiments, the adjustment signal 412a may be a digital value that is proportional to the time difference identified by the timing / phase error detector 410.

A summing module 406 is coupled to receive the unadjusted theta signal 404a (ie, a continuous set of digital values representing a ramp signal that is reset at a fixed phase) and the adjustment signal 412a And generate theta signal 406a.

In operation, the theta signal 406a is a ramp signal that is reset, such as the unadjusted theta signal 404a, but for this purpose the reset times of the ramp signal are set in time according to the value of the adjustment signal 412a. In other words, it should be understood that the shift to the adjusted phase.

A modulation profile look up table and a processor 408 are coupled to receive the theta signal 406a. The modulation profile lookup table and processor 408 are configured to store therein one or more modulation profiles, eg, a value representing modulation profile 242 of FIG. 2.

In operation, the theta signal 406a is used in the order between the modulation profile lookup table and the values of the stored modulation signal in the processor 408. The motor as identified in the position reference and the detected zero-crossing signal 418 in which the phase of the theta signal 406a represented by the reset portions of the theta signal 406a is identified in the detected position reference signal 414. It will be appreciated that it can be adjusted according to the time difference between the zero crossings of the current in the winding. Accordingly, the phase, i.e., timing, of the modulation profile lookup table and the modulation signal 408a generated in the processor 408 may be adjusted.

The modulation profile lookup table and the processor portion of the processor 408 may be arranged in different fixed phases, for example in the modulation profiles 244, 246 of FIG. 2. Other modulation profiles 408b and 408c may be automatically generated which may be in fixed phases with respect to modulation profile 242.

Example circuits and methods for detecting zero current through motor windings are described next in conjunction with FIGS. 5-8. However, it should be appreciated that other methods can be used to detect zero current through the motor windings.

Referring now to FIG. 5, three half bridge circuits 502, 504, 506 correspond to the three half bridge circuits 112/114, 116/118, 120/122 of FIG. 1, driving the three motor windings. It is shown to make. The currents through the half bridge circuit 502 and through one of the motor windings are represented by dashed lines identified by the circle numbers ①, ② and ③. The currents ①, ② and ③ are different at different times during the positive polarity of the current signal in the motor winding, for example during the positive portions of the current signal 262 of FIG. 2. Currents through 502. The current ① indicates that the upper FET is on, the current ③ indicates that the lower FET is on, and the current ② indicates that both FETs are turned off. The current? Passes through the intrinsic diode of the lower FET so that the voltage VoutA (see, for example, signal 124 in FIG. 1) is initiated when the two FETs of the half bridge 502 are turned off. It will be appreciated that it implements approximately 0.7 volts, a voltage below ground, and returns to ground voltage when the lower FET is turned on. Thus, by detecting the voltage VoutA going below ground and back to ground, it will be appreciated that the actual zero current through the half bridge 502 and through the associated motor windings can be identified.

Referring now to FIG. 5A, in which the same elements as in FIG. 5 are denoted by the same reference numerals, the currents through the half bridge circuit 502 and through one of the motor windings are identified by the circle numbers ①, ② and ③. Represented by dashed lines. The currents 1, 2 and 3 are at half time during the negative polarity of the current signal in the motor winding, for example during the negative portions of the current signal 262 of FIG. 2. Indicate currents through 502. The current ① indicates that the upper FET is on, the current ③ indicates that the lower FET is on, and the current ② indicates that both FETs are turned off. The current? Passes through the intrinsic diode of the upper FET, so that the voltage VoutA realizes approximately 0.7 volts above the voltage VM when the two FETs of the half bridge 502 are turned off, and the upper FET It will be appreciated that the voltage returns to the voltage VM when is turned on. Thus, it will be appreciated that the actual zero current through the half bridge 502 and through the associated motor windings can be ascertained by detecting the voltage VoutA going beyond the voltage VM and back to the voltage VM.

Referring now to FIG. 6, graph 600 has a horizontal axis scaled in units of time in arbitrary units and a vertical axis scaled in units of current in arbitrary units. Graph 620 has a horizontal axis scaled in units of time in arbitrary units and a vertical axis scaled in units of voltage in arbitrary units. Graph 640 has a horizontal axis scaled in units of time in arbitrary units and a vertical axis scaled in units of voltage in arbitrary units.

Signal 602 represents a current signal in motor winding A when a sinusoidal drive signal is used. The current signal 602 may be the same as or similar to the current signal 262 of FIG. 2. As mentioned above, when the pulse width modulation drive signal is used, the current signal 602 may appear more complex, but the signal 602 generally represents the average current through the winding A. The current signal has a zero crossing at times 606 and 608.

The modulation signal 622 may be the same as or similar to the modulation signal 242 of FIG. 2. The modulated signal 622 has six time intervals or phases in which the nets 604a, 604b, 604c, and 604d are shown.

A pulse width modulated signal 642 can be generated in accordance with the modulation waveform 622, and times high duty cycle 642a, 642b at times of peaks 622a, 622b of the modulation waveform 622. And lower duty cycle times in times of other portions of the modulation waveform 622 according to the values of the modulation waveform 622. The PWM signal 642 may be a signal actually applied to the motor winding A 104a of the motor 104 of FIG. 1 to drive a sinusoidal shape.

Referring now to FIG. 7, pulse width modulated pulses 702, 702 ′ represent the pulse width modulated pulses 642 of FIG. 6 during the negative portions of the current signal 602. Pulse width modulated pulse 704 represents the pulse width modulated pulses 642 of FIG. 6 during the bipolar portions of the current signal 602.

The pulse width modulation pulses 702 and 702 'have raised or transient portions 702b, 702c, 702b' and 702c 'and steady state portions 702a and 702a'. As discussed above in conjunction with FIGS. 5 and 5A, when both transistors of the half bridge, eg, FETs, are turned off, the voltage VoutA appearing on the associated motor winding is the polarity of the current in the motor winding, ie the current. It will be appreciated that depending on the polarity of the signal 602, the motor voltage VM temporarily progresses above or below the threshold. Further, each major edge transition of the pulse width modulated signals 702, 704, 702 'proceeds at short time intervals while both the FETs can be turned off or else both FETs can be turned on at the same time, thus providing the motor voltage It will be appreciated that this will cause a short between VM and ground. Thus, when the two FETs are turned off, this results in the transient signal portions 702b, 702c, 704b, 704c, 702b ', and 702c'. The transient signal portions 702b, 702c, 704b, 704c, 702b ', 702c' may occur for a short time interval, for example about six hundred nanoseconds.

The direction of the transient voltage signal portions 702b, 702c, 704b, 704c, 702b ', 702c' depends on the occurrence of the zero crossing of the current signal 602, that is, at times 606, 608. The change will be clear. Thus, detection of changes in the direction of the transient signal portions 702b, 702c, 704b, 704c, 702b ', 702c' can be used to confirm the zero current in the associated motor winding.

Referring now to FIG. 7A, graph 720 has a horizontal axis scaled in units of time in arbitrary units and a vertical axis scaled in units of voltage in arbitrary units. Graph 740 has a horizontal axis scaled in units of time in arbitrary units and a vertical axis scaled in units of current in arbitrary units.

Signal 722 represents the pulse width modulated signal 642 of FIG. 6, but transient signal portions such as transient portions 702b, 702c, 704c, 704d, 702b ′ and 702c ′ of FIG. 7 are shown. Signal 742 may be the same as or similar to current signal 602 of FIG. 6.

Times t1-t9 occur during the transient signal portions. It will be clear from the foregoing discussion with FIGS. 5 and 5A that the transient signal portions occur when both FETs of the associated half bridge circuit driving the motor windings are turned off.

For reasons discussed above in conjunction with FIGS. 5, 5A and 7, at time t6, the transient signal portion changes orientation at the same time or nearly simultaneously with the zero crossing of the current signal 742. Thus, the change in orientation of the transient signal portions can be used to detect zero current crossings in the motor windings. In particular, at the times t1-t5, the transient signal portions extend above the motor voltage VM. Conversely, at the times t6-t9, the transient signal portions extend below ground. Other changes or orientations (not shown) of the transient signal portions occur at the next zero crossing of the current signal 742 and may also be used to detect the next zero crossing.

In some embodiments, a circuit (see, for example, comparators 808 and 810 shown in FIG. 8 below) is at or near the times t1-t9 and subsequent other similar times. Can also operate to sample the signal VoutA 722 to detect only the signal transients. The times t1-t9 and subsequent similar times are known because both FETs are briefly turned off at these times. In other embodiments, the signal 722 can be continuously sampled to detect the transient signal portions.

In some embodiments, changes in the orientations of the transient signal portions can be detected with two comparators. Both zero crossings of the current signal 742 may be detected. However, in other embodiments, one comparator may be used to detect the presence or absence of transient signal portions extending upwards or downwards. Furthermore, both zero crossings of the current signal 742 can be detected with one comparator.

Referring now to FIG. 8, where the same elements as in FIG. 1 are denoted by the same reference numerals, a zero current detection module 802 may be the same as or similar to the current measurement module 144 of FIG. 1.

The zero current detection module 802 may include a first comparator 808 connected to the three motor windings via a selectable switch 804. The zero current detection module 802 may also include a second comparator 810 connected to the three motor windings via a selectable switch 806. The first comparator 808 may be connected to receive a reference voltage equal to or close to the motor voltage VM. The second comparator 810 may be connected to receive a reference voltage equal to or close to ground.

The first comparator 808 is configured to generate an output signal 808a indicative of a voltage on a selected motor winding that progresses above the motor voltage. The second comparator 810 is configured to generate an output signal 810a indicative of the voltage on the selected motor winding going below ground. Thus, in operation, the first comparator 808 is operable to detect positive transient signal portions 702b, 702c, 702b ', and 702c' of the pulse width modulated signal of FIG. 7 associated with driving a sinusoidal motor. can do. Similarly, in operation, the second comparator 810 may be operable to detect negative transient signal portions 704b, 704c of the pulse width modulated signal of FIG. 7 associated with driving a sinusoidal motor. As mentioned above, the edges of these signal portions can be used to identify the zero current crossing in the associated motor winding.

The zero current detection module 802 is also coupled to receive the output signals 808a and 810a and is configured to generate an output signal 812a representing a selected one of the output signals 808a and 810a. (multiplexer) 812.

The multiplexer 812 may be connected to receive a control signal 146d from the modulated signal generation module 146. The switches 804 and 806 may be connected to receive other control signals (not shown) from the modulated signal generation module 146.

The modulating signal generation module 146 may use various types of logic to identify zero current crossings within one or more of the motor windings. For example, as discussed above in conjunction with FIGS. 7 and 7A, for a pulse width modulated sinusoidal motor drive signal, the output signals 808a, 810a are transient signals of the pulse width modulated signal 642. It may be used to confirm the change in the direction of the (702b, 702c, 704b, 704c, 702b ', 702c'). In essence, the multiplexer 812 can be switched to view another comparator any time a detection of a particular direction of the transient signal portions is made.

In some embodiments, the switches are not used, and only one motor winding is used to provide signals to the comparators 808 and 810. In some embodiments, only one comparator is used, and the multiplexer 812 is not necessary. Various other types of logic may be used to determine the zero crossing of the current through the motor winding using the techniques described above as the voltage on the motor winding proceeds above the motor voltage VM and / or below ground. May be used by the signal generation module 146.

Referring now to FIG. 9, graph 900 has a horizontal axis scaled in units of time in arbitrary units. The graph 900 also has a vertical axis scaled in units of current in arbitrary units. Graph 920 has a horizontal axis scaled in units of time in arbitrary units. The graph 920 also has a vertical axis dimensioned in units of the eye of arbitrary units.

Signal 904 represents a trapezoidal motor drive as opposed to the sinusoidal motor drive signals described above. The signal 904 represents a trapezoidal current signal on the motor windings.

It will be appreciated that the voltage waveform 922 represents the actual voltage applied to the motor windings for 100 percent motor drive. For one hundred percent motor drive, the signal 922 implements the VM's voltage (motor voltage) with a duty cycle of one hundred percent, and is zero at other times. For another trapezoidal motor drive (not shown), which is less than one hundred percent, during the time interval when the one hundred percent drive signal 922 implements the voltage VM, the duty is dependent on the other trapezoidal motor drive being less than one hundred percent motor driven. Provide a pulse width modulated signal with pulse width modulation with cycles.

The time of motor electric rotation can be divided into six states, in which only four states 902a, 902b, 902c, and 902d are shown. The signals during the other two states will be clear. Each one of the motor windings receives a motor drive signal, such as motor drive signal 922, but the phase is shifted and starts at the other of the phases.

By trapezoidal driving, the drive signal applied to the motor windings is zero during the first phase 902a and during the fourth phase 902d. Thus, during the first and fourth phases 902a and 902d, the current signal 904 implements zero current during the signal portion 904a and during the signal portion 904d. The zero current is not immediately realized at the start of the first and fourth phases 902a, 902d due to the inductive action of the motor winding. For the reasons described above in conjunction with FIG. 1, when the drive voltage applied to the winding is zero and the current decays to zero, the counter electromotive force voltage can be observed directly across the winding.

For the reasons described above in more detail in conjunction with FIGS. 5 and 5A, during signal portion 922a, signal 922 on the motor winding implements a voltage of VM + Vd, and during signal portion 922d, the signal ( 922 implements a voltage of -Vd. An exemplary method of detecting the zero current during signal portions 904a and 904d has been described above in conjunction with FIGS. 5 and 5A. To this end, portions 922a and 922d of the signal 922 may be used to detect the zero winding current using circuits and techniques such as those described above in conjunction with FIGS. 5, 5A and 8. Can be.

During some of the first and fourth phases 902a, 904d, in particular during the dashed portions 922b, 922e of the voltage signal 922, the counter electromotive force voltage can be observed directly. During portions 922b and 922e of the voltage signal 922 and during portions 922a and 922d, no drive signal is applied to the associated motor. As described above, the induction behavior of the motor windings causes a current through the motor windings to implement zero current only during portions 922b and 922e of the drive signal 922.

From the foregoing discussion, with trapezoidal drive and six motor drive states, when each motor winding is not driven, for example, the motor windings together signal one sixth of the motor electrical rotation (ie sixty degrees). It should be understood that there are substantial time intervals while not driving during the time intervals associated with portions 922a and 922b. The current through the motor winding is zeroed at the ends of transient signal portions 922a and 922d, ie during signal portions 922b and 922e. During the signal portions 922b and 922e, the counter electromotive force voltage can be observed directly. Thus, unlike the sinusoidal drive described above, for motor windings continuously driven in the trapezoidal drive arrangement of the six states, the transient signal portions 922a, 922d whose ends represent zero winding current are detected. Alternatively, it is not necessary to separately create a time window while no motor drive is applied to the winding to detect zero crossings during the signal portions 922b and 922e indicating the motor rotational position.

All references mentioned herein are incorporated by reference in their disclosure.

While various concepts, structures, and techniques have been described above, and preferred embodiments have been described that fall within the scope of the present invention, those skilled in the art may, among others, include those concepts, structures, and techniques. It will be apparent that embodiments may be used. Accordingly, it is to be understood that the scope of the present invention is not limited to the described embodiments, but is limited by the spirit and scope of the following claims.

Claims (28)

In a method of driving a multi-phase motor having a plurality of motor windings,
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 an angular rotation of the motor;
Comparing a phase of the zero current signal and a phase of the position reference signal to generate a phase comparison signal;
Generating a plurality of modulated signals, each having a phase related to a value of the phase comparison signal; And
Generating a plurality of motor drive signals for the plurality of motor windings in accordance with the plurality of modulated signals, wherein generating the plurality of modulated signals comprises:
Providing a look up table in which modulation values are stored corresponding to at least one shape of the plurality of modulation signals;
Generating a first continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;
Converting the first continuous sawtooth ramp signal to a second continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value; Adding to a value associated with s i, wherein the smallest and largest values of the second consecutive sawtooth ramp signal are adjusted times from the smallest and largest values of the first continuous sawtooth ramp signal. Shifted in time by the adjustment time being related to the phase comparison signal;
Using the adjusted continuous sawtooth ramp signals to continuously find values in the lookup table to generate at least one of the plurality of modulated signals;
Generating at least one other modulated signal in a predetermined phase relationship to at least one of the plurality of modulated signals. 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. 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. The method of claim 1, wherein generating the position reference signal comprises:
Stopping a motor drive signal for at least one of the plurality of motor windings during a time window proximate the motor embodying the reference position; And
Detecting the reference position during the time window by zero crossing of a back electromotive force signal. The method of claim 1, wherein generating the zero current signal comprises:
Generating the plurality of motor drive signals with each of a plurality of half bridge circuits connected to the electric motor,
Each half bridge circuit,
Respective first and second series connected transistors;
Each power supply high voltage node for receiving a high power supply voltage;
Each power supply low voltage node for receiving a low power supply voltage; And
Each output node on which one of each of the plurality of motor drive signals is generated;
Detecting a reverse current passing through at least one of the first or second transistors of the plurality of half bridge circuits,
The detecting step,
Detecting a voltage at the output node above the high power supply voltage; or
Detecting a voltage at the output node below the low power supply voltage,
Generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings in accordance with detecting the reverse current. The method of claim 5, wherein detecting the reverse current comprises:
Detecting the reverse current by sampling a voltage only at the output node at times when both the first and second transistors are turned off. The method of claim 1, wherein each one of the plurality of motor drive signals,
Each of the plurality of pulse width modulated signals, each one of the plurality of pulse width modulated signals having steady state high values proximate the high power supply voltage and transient high values higher than the high power supply voltage. Have high states, each one of said plurality of pulse width modulated signals also has low states having steady state low values proximate said low power supply voltage and transient low values lower than said low power supply voltage; How to. An electronic circuit for driving a polyphase motor having a plurality of motor windings,
A current measurement module configured to generate a zero current signal indicating a zero crossing of current through at least one of the plurality of motor windings;
A position measuring module, configured to generate a position reference signal indicating a reference position of each rotation of the motor;
A modulated signal configured to compare a phase of the zero current signal and a phase of the position reference signal to generate a phase comparison signal, each of which is configured to generate a plurality of modulated signals having a phase related to a value of the phase comparison signal Generation module; And
A drive circuit configured to generate a plurality of motor drive signals for the plurality of motor windings in accordance with the plurality of modulated signals, wherein the modulated signal generation module comprises:
A lookup table storing modulation values corresponding to at least one shape of the plurality of modulation signals;
A tooth generator configured to generate a first continuous tooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;
A timing / phase error detector coupled to receive a signal indicative of the zero current signal, coupled to receive a signal indicative of the position reference signal, and configured to generate a signal indicative of the phase comparison signal ); And
The first continuous to a value associated with the phase comparison signal to generate a second continuous sawtooth ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value. And a summation module configured to add the sawtooth ramp signal, wherein the smallest and largest values of the second consecutive sawtooth ramp signal are the smallest and largest of the first continuous sawtooth ramp signal. Shifted in time by an adjustment time from values, the adjustment time being associated with the phase comparison signal, wherein the adjusted continuous sawtooth ramp signal is generated in the lookup table to generate at least one of the plurality of modulation signals. Used to sequentially find the values and write down in a predetermined phase relationship to at least one of the plurality of modulated signals An electronic circuit which is used to generate one other modulated signal. 9. The electronic circuit of claim 8, wherein the position measurement module is further configured to generate the position signal in accordance with a hall signal generated by a hall sensor disposed in proximity to the motor. 9. The electronic circuit of claim 8, wherein the position measurement module is further configured to generate the position signal in accordance with a back EMF signal generated in a motor winding. The method of claim 8, wherein generating the position reference signal comprises:
Stopping a motor drive signal for at least one of the plurality of motor windings during a time window proximate the motor embodying the reference position; And
Detecting the reference position during the time window by zero crossing of the back EMF signal. The method of claim 8,
A plurality of half bridge circuits coupled to the electric motor and configured to generate the plurality of motor drive signals,
Each half bridge circuit,
Respective first and second directly connected transistors;
Each power supply high voltage node for receiving a high power supply voltage;
Each power supply low voltage node for receiving a low power supply voltage; And
Each output node on which one of each of the plurality of motor drive signals is generated,
Further comprising at least one comparator, wherein the comparator,
A voltage at the output node that is above the high power supply voltage; or
At least each of which represents a reverse current through at least one of the first and second transistors of at least one of the plurality of half bridge circuits by detecting at least one of the voltages at the output node that is less than or equal to the low power supply voltage. Generate one comparator output signal;
And a processor configured to generate the zero current signal indicative of the zero crossing of the current through at least one of the plurality of motor windings in accordance with the at least one comparator output signal. 13. The method of claim 12, wherein detecting further comprises detecting the reverse current by sampling a voltage at the output node only at times when both the first and second transistors are turned off. Electronic circuit. The method of claim 8, wherein each one of the plurality of motor drive signals,
Each of the plurality of pulse width modulated signals, wherein each one of the plurality of pulse width modulated signals has a high steady state high values proximate the high power supply voltage and a high high transient value higher than the high power supply voltage. And each one of said plurality of pulse width modulated signals also has low states having steady state low values proximate said low power supply voltage and transient low values lower than said low power supply voltage. Electronic circuit. A method for driving a multiphase motor having a plurality of motor windings, the method comprising:
Generating a motor drive signal with a half bridge circuit coupled to the electric motor,
The half bridge circuit,
First and second series connected transistors;
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
And an output node for generating the motor drive signal,
Detecting a reverse current through at least one of the first and second transistors,
The detecting step,
Detecting a voltage at the output node that is above the high power supply voltage; or
Detecting at least one voltage at the output node below the low power supply voltage;
Generating a zero current signal indicative of a zero crossing of current through at least one of the plurality of motor windings in accordance with detecting the reverse current, the method comprising:
Generating a position reference signal indicative of a reference position of each rotation of the motor;
Comparing a phase of the zero current signal and a phase of the position reference signal to generate a phase comparison signal;
Generating a plurality of modulated signals, each having a phase associated with a value of the phase comparison signal; And
Generating a plurality of motor drive signals for the plurality of motor windings in accordance with the plurality of modulated signals, wherein generating the plurality of modulated signals comprises:
Providing a lookup table in which modulation values are stored corresponding to at least one shape of the plurality of modulation signals;
Generating a first continuous ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;
The first continuous ramp at a value associated with the phase comparison signal to generate a second continuous ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value. Adding a signal, wherein the smallest and largest values of the second continuous ramp signal are shifted in time by an adjustment time from the smallest and largest values of the first continuous ramp signal And the adjustment time is related to the phase comparison signal. The method of claim 15, wherein detecting the reverse current comprises:
Detecting the reverse current by sampling a voltage at the output node only at times when both the first and second transistors are turned off. The method of claim 15, wherein the motor drive signal,
A high state comprising a plurality of pulse width modulated signals, each one of said plurality of pulse width modulated signals having steady state high values proximate said high power supply voltage and transient high values higher than said high power supply voltage; Wherein each one of said plurality of pulse width modulated signals also has low states having steady state low values proximate said low power supply voltage and transient low values lower than said low power supply voltage. Way. The method of claim 15, wherein generating the position reference signal,
Generating a hall sensor signal to a hall sensor disposed proximate to the motor. The method of claim 15, wherein generating the position reference signal,
Generating a back EMF signal with a back EMF module coupled to at least one of the plurality of motor windings. The method of claim 15, wherein generating the position reference signal,
Stopping a motor drive signal for at least one of the plurality of motor windings during a time window proximate the motor embodying the reference position; And
Detecting the reference position during the time window by zero crossing of a back electromotive force signal. The method of claim 15, wherein generating the plurality of modulated signals comprises:
Using the adjusted continuous ramp signal to continuously find values in the lookup table to generate at least one of the plurality of modulated signals; And
Generating at least one other modulated signal in a predetermined phase relationship with at least one of the plurality of modulated signals, each modulated signal associated with each one of the plurality of pulse width modulated (PWM) signals Characterized in that the method. An electronic circuit for driving a polyphase motor having a plurality of motor windings,
A half bridge circuit coupled to the electric motor to generate a motor drive signal,
The half bridge circuit,
First and second series connected transistors;
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
And an output node for generating the motor drive signal,
A voltage at the output node that is above the high power supply voltage; Or generate each of at least one comparator output signal indicative of reverse current through at least one of the first and second transistors by detecting at least one of the voltage at the output node that is less than or equal to the low power supply voltage. At least one comparator configured;
The electronic circuit,
A processor configured to generate a zero current output signal indicative of a zero crossing of current through at least one of the plurality of motor windings in accordance with the at least one comparator output signal;
A position measuring module, configured to generate a position reference signal indicating a reference position of each rotation of the motor; And
A modulation signal configured to compare a phase of the zero current signal with a phase of the position reference signal to generate a phase comparison signal, each of which is configured to generate a plurality of modulation signals having a phase associated with a value of the phase comparison signal Further comprising a generation module, The modulated signal generation module,
A lookup table in which modulation values are stored corresponding to at least one shape of the plurality of modulation signals;
A ramp signal generator configured to generate a first continuous ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value;
A timing / phase error detector configured to receive a signal indicative of the zero current signal and configured to receive a signal indicative of the position reference signal and to generate a signal indicative of the phase comparison signal; And
The first continuous ramp at a value associated with the phase comparison signal to generate a second continuous ramp signal having a smallest value and a largest value and a plurality of values between the smallest value and the largest value. An adding module configured to add a signal, wherein the smallest and largest values of the second continuous ramp signal are timed by an adjustment time from the smallest and largest values of the first continuous ramp signal. And the adjustment time is related to the phase comparison signal. The method of claim 22, wherein the detecting step,
Detecting the reverse current by sampling a voltage at the output node only at times when both the first and second transistors are turned off. The method of claim 22, wherein the motor drive signal,
A high state comprising a plurality of pulse width modulated signals, each one of said plurality of pulse width modulated signals having steady state high values proximate said high power supply voltage and transient high values higher than said high power supply voltage; Wherein each one of said plurality of pulse width modulated signals also has low states having steady state low values proximate said low power supply voltage and transient low values lower than said low power supply voltage. Electronic circuit. 23. The electronic circuit of claim 22 wherein the position measurement module is further configured to generate the position signal in accordance with a Hall signal generated by a Hall sensor disposed proximate to the motor. 23. The electronic circuit of claim 22 wherein the position measurement module is further configured to generate the position signal in accordance with a back EMF signal generated in a motor winding. 23. The apparatus of claim 22, wherein the electronic circuitry is configured to stop a motor drive signal for at least one of the plurality of motor windings during a time window proximate to the motor embodying the reference position, wherein the position measurement module is configured to: And generate the position reference signal indicative of the reference position during a time window. 23. The method of claim 22, wherein the signal of the adjusted continuous ramp is used to continuously find values in the lookup table to generate at least one of the plurality of modulation signals, and for at least one of the plurality of modulation signals. And generate one or more other modulated signals in a predetermined phase relationship, each modulated signal associated with each one of said plurality of pulse width modulated (PWM) signals.

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