CN113541569B - Motor drive device, method, air conditioner, and computer-readable storage medium - Google Patents

Abstract

The invention provides a motor driving device, a method, an air conditioner and a computer readable storage medium, wherein the motor driving device comprises a preceding stage processing circuit and a three-phase inverter circuit, the preceding stage processing circuit is used for inputting alternating current output by a power supply into the three-phase inverter circuit, the connection point of an upper bridge arm switching element and a lower bridge arm switching element of each phase of the three-phase inverter circuit is connected with a motor, and the motor driving device also comprises a control device which is used for counteracting conduction interference and leakage current caused by the change of phase voltage of another phase by using the change of the phase voltage of one phase of the motor. The invention changes the switching timing and pulse width of the upper and lower bridge arm switching elements of each phase according to the current direction detected by the current detection device by arranging the current detection device in the driving loop, controls the waveform of one-phase voltage applied to the motor, can effectively compensate the voltage deviation caused by dead time, eliminates current distortion, and simultaneously reduces conduction interference and leakage current generated in the switching process of the other phase by using the change of the one-phase voltage.

Description

Motor drive device, method, air conditioner, and computer-readable storage medium

technical field

The present invention relates to the field of switching power supplies, and in particular, to a motor driving device, a method, an air conditioner, and a computer-readable storage medium.

Background technique

In the past, due to the rapid changes in voltage or current generated by the converter and inverter installed in the motor drive device during switching operations, high-frequency leakage current from the capacitor to the ground is generated, and the input and output of the switching power supply are generated. The terminal produces strong conduction interference, and leakage current and conduction interference sometimes become the cause of equipment failure or misjudgment in the air conditioner.

Japanese Patent Laid-Open No. 10-094244 discloses a common-mode interference canceller, which uses a star-connected capacitor to detect the common-mode voltage generated by the semiconductor elements of the voltage-type PWM inverter during switching operations, and performs power conversion by switching the power semiconductor elements. , the control voltage source generates a voltage with the same magnitude and opposite polarity as the common-mode voltage from the detected common-mode voltage, and the common-mode transformer superimposes the voltage generated by the control voltage source on the output end of the inverter to offset the common-mode voltage, Adopting this setting requires additionally setting up a more complicated loop, and the cost is high.

Japanese Patent Laid-Open No. 9-233837 discloses an inverter device, an anti-leakage device and an anti-leakage method for an inverter to drive a load. The inverter device is provided with an impedance equivalent to the leakage impedance of the main load. The switch unit that supplies the voltage, the drive unit that drives the switch unit, the switch unit uses the output terminal of the main converter as a power source, and through the switch unit, the voltage between the ground and the reverse phase of each phase generated by the switching operation of the inverter is converted. It is applied to the equivalent impedance equivalent to the load leakage impedance, and the leakage current generated by the switching operation of the power conversion equipment is eliminated. With this setting, it is necessary to add components such as the equivalent impedance, the switching part, and the driving part. The cost impact is also greater.

In addition, the inverter in the motor drive device is usually composed of a switching element connected in parallel with a circulating diode, and the series circuit composed of the switching element on the upper arm side and the switching element on the lower arm side is divided into three phases. The mutual connection point of the upper arm and the lower arm is connected to the load. Since the switching elements of the upper arm and the lower arm are connected in series, if the two switching elements are turned on at the same time in a short period of time, a short circuit will occur and the switch will be destroyed. elements, therefore, a dead time is provided during motor drive so that a delay occurs when each switching element is turned on, in which case the diode connected to the negative side of the power supply conducts when the phase current is of positive polarity, at During the dead time, the output voltage of the inverter becomes negative, and the time when the output voltage is positive becomes shorter, resulting in a deviation of the output voltage.

Japanese Patent Laid-Open No. 3-117369 discloses an inverter voltage control device, including an inactive time compensation that compares the output voltage of the inverter with a PWM control voltage, and corrects the PWM control signal to compensate for the inactive time of the inverter bridge The loop, a circuit for load current compensation, the load current compensation circuit detects the output current of the inverter and corrects the PWM control signal to compensate for the voltage drop of the main circuit caused by the load current. In this scheme, although it can be compensated The current is distorted by the dead time of the inverter, but because the pulse timing of the output voltage is not synchronized, the interference accompanying the switch occurs greatly, and the interference or leakage current from the inverter cannot be reduced.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The problem solved by the present invention is that, in the prior art, in order to solve the conduction interference or leakage current when the motor is driven, an additional loop needs to be set up, which increases the cost, and the setting of the dead time in the motor drive will lead to deviation of the output voltage.

In order to solve the above problems, the present invention provides a motor drive device, a motor drive device for driving a motor, and the motor is a three-phase motor, which is characterized in that it includes a pre-processing circuit and a three-phase inverter circuit, The pre-processing circuit is used to input the AC power output by the power supply into the three-phase inverter circuit, and the three-phase inverter circuit includes the power supply line of the upper bridge arm and the power supply line of the lower bridge arm, and the power supply line of the upper bridge arm. and the lower bridge arm power line, the upper bridge arm switch element and the lower bridge arm switch element connected in series in each phase, the connection point between the upper bridge arm switch element and the lower bridge arm switch element of each phase is connected to the motor, and also includes A control device, the control device is used to control the switching timing of the upper arm switching element and the lower arm switching element of each phase, and use the variation of the phase voltage of one phase of the motor to offset the conduction disturbance caused by the variation of the phase voltage of the other phase and leakage current.

The variation of the phase-to-phase voltage of one phase of the motor offsets the conducted interference and leakage current caused by the variation of the phase-to-phase voltage of the other phase. The switching element or the switching element of the lower bridge arm performs opposite switching actions at the same time. The opposite switching action means that in the upper bridge arm or the lower bridge arm, the switching element of one phase is turned on, and the switching element of the other phase is turned off. This technical solution can The conduction interference and the leakage current of the motor generated by the switching element during the switching process are significantly reduced. The technical solution has nothing to do with the direction of the current, but is only related to the switching timing of the upper-side switching element and the lower-side switching element.

Further, a current detection device is provided between the power line of the lower arm and the pre-processing circuit, the current detection device is used to detect the current output by each phase, and the control device is based on the current detection device. The detected current direction controls the pulse width and time of the upper and lower arm switching elements of each phase, and compensates for the delay caused by the dead time of the upper and/or lower arm switching elements of each phase. resulting voltage offset.

By adjusting the pulse width and time of the upper arm switching element and the lower arm switching element of each phase, the voltage output of each phase when the current flows in different directions is changed. When the current direction is negative, the output voltage in the dead time is the voltage on the high-voltage side. When the current direction is positive, the output voltage at the dead time is the voltage on the low-voltage side, and the average output voltage of each phase does not change according to the current direction. The setting compensates for voltage offset due to dead time, eliminating current distortion caused by dead time in the prior art.

Further, the control device includes:

a three-phase output voltage command generation module, configured to generate a three-phase voltage command; the three-phase voltage command includes a U-phase voltage command, a V-phase voltage command and a W-phase voltage command;

a current direction detection module for judging the current flow direction according to the current detected by the current detection device, and inputting the current flow direction judgment result into the carrier selection module;

a saw wave generation module, used to generate several groups of saw waves, and the several groups of the saw waves are the carriers of pulse output;

The carrier selection module is used to select and input the carrier of each phase from several groups of saw waves output by the saw wave generation module according to the judgment result of the current direction detection module;

The comparator module is used to compare the three-phase voltage command and the carrier wave, and output the driving pulse of the switching element according to the comparison result;

The switching element driving module is used for driving and controlling the switching element to be turned on or off according to the driving pulse output by the comparator module.

Through the above settings, the switching elements between the two phases in the same bridge arm can perform opposite actions at the same time, cancel each other out the conduction interference and leakage current generated during the switching action, and reduce the overall conduction interference and leakage current by about half , has a significant effect, and can also compensate for the voltage offset caused by the dead time, eliminating the current distortion caused by the dead time in the prior art, regardless of the direction of the current flowing in the motor. It is possible to output an output voltage that is not affected by the dead time caused by the switching of the upper and lower arms of each phase.

The invention also discloses a motor driving method for driving the motor, wherein the motor is a three-phase motor, and is characterized in that the driving method comprises: controlling an upper arm switch element and a lower arm switch element of each phase of the motor The switching timing of , in one carrier cycle Tc, at least one moment, the upper arm switching element or the lower arm switching element between different two phases in the motor simultaneously perform opposite switching actions.

The technical solution can significantly reduce the conduction interference generated by the switching element during the switching process and the leakage current of the motor.

Further, detect the current direction of each phase of the motor, control the pulse width and time of the upper arm switching element and the lower arm switching element of each phase according to the current direction, and compensate for the upper arm switching element and/or lower arm switching element of each phase. Voltage offset due to dead time of switching elements.

By adjusting the pulse width and time of the upper arm switching element and the lower arm switching element of each phase, the voltage output when each phase current flows in different directions is changed. When the U-phase and V-phase current directions are both negative, the The output voltage at the dead time is the voltage on the high voltage side. When the U-phase and V-phase current directions are both positive, the output voltage at the dead time is the voltage on the low voltage side, and the average output voltage of each phase does not change. It varies according to the change of the current direction, that is, the setting compensates for the voltage offset caused by the dead time, which eliminates the current distortion caused by the dead time in the prior art.

Further, control the switching timing of the upper arm switching element and the lower arm switching element of each phase according to the change of the carrier wave, or select the driving pulse required for the upper arm switching element and the lower arm switching element of each phase according to the current direction. and control the pulse width and time of the upper bridge arm switching element and the lower bridge arm switching element of each phase according to the carrier wave.

Controlling switch timing and/or pulse width based on the carrier is simple and effective with limited impact on cost.

Further, the carrier is a saw-shaped carrier, including:

the first carrier wave, the first carrier wave is a sawtooth wave with a positive slope with respect to time in one carrier cycle Tc;

a second carrier wave, the second carrier wave is a sawtooth wave having a negative slope with respect to time in one carrier cycle Tc;

a third carrier, the third carrier is a sawtooth wave whose time is advanced by the dead time relative to the first carrier;

the fourth carrier, the fourth carrier is a sawtooth wave whose time is advanced by the dead time relative to the second carrier;

a fifth carrier, the fifth carrier is a sawtooth wave whose time is delayed by the dead time relative to the first carrier;

The sixth carrier is a sawtooth wave whose time is delayed by the dead time with respect to the second carrier.

Through the change of multiple carriers, the pulse width and/or switching timing of each phase of the motor can be controlled, which can effectively reduce the conduction interference and leakage current when the switching element performs switching operations, and can also reduce the output voltage deviation caused by dead time. Eliminate current distortion.

Further, the motor includes U-phase, V-phase, and W-phase. The upper bridge arms of U-phase, V-phase and W-phase are sequentially provided with a first switch, a third switch, and a fifth switch, and the lower bridge arms are sequentially provided with a second switch, The fourth switch and the sixth switch select the sixth carrier as the driving pulse carrier of the first switch, and the second carrier as the driving pulse carrier of the second switch; select the third carrier as the driving pulse carrier of the third switch, and the first carrier as the driving pulse carrier of the third switch. The driving pulse carrier of the fourth switch.

The setting realizes that the switching elements between the two phases in the same bridge arm perform opposite switching actions at the same time, and mutually cancel the conduction interference and leakage current generated during the switching action.

Further, the motor includes U-phase, V-phase, and W-phase. The upper bridge arms of U-phase, V-phase and W-phase are sequentially provided with a first switch, a third switch, and a fifth switch, and the lower bridge arms are sequentially provided with a second switch, The fourth switch and the sixth switch, when the U-phase and V-phase current directions are both positive, select the second carrier as the driving pulse carrier of the first switch, the fourth carrier as the driving pulse carrier of the second switch, and select the first carrier As the driving pulse carrier of the third switch, the fifth carrier is used as the driving pulse carrier of the fourth switch; when the U-phase and V-phase current directions are both negative, the sixth carrier is selected as the driving pulse carrier and the second carrier of the first switch. As the driving pulse carrier of the second switch, the third carrier is selected as the driving pulse carrier of the third switch, and the first carrier is selected as the driving pulse carrier of the fourth switch.

This setting compensates for the voltage offset due to dead time, eliminating the current distortion caused by dead time in the prior art.

The present invention also discloses an air conditioner, comprising a computer-readable storage medium storing a computer program and a processor, and when the computer program is read and run by the processor, the above-mentioned motor driving method is implemented.

The air conditioner and the above-mentioned motor driving method have the same advantages over the prior art, which will not be repeated here.

The present invention also discloses a computer-readable storage medium, where a computer program is stored in the computer-readable storage medium, and when the computer program is read and executed by a processor, the above-mentioned motor driving method is implemented.

Compared with the prior art, the motor drive device, method, air conditioner and computer-readable storage medium of the present invention have the following advantages:

In the present invention, a current detection device is arranged in the driving circuit, and according to the current direction detected by the current detection device, the switching timing of the upper and lower bridge arm switching elements of each phase is changed, and the change of the phase voltage of one phase is used to reduce the voltage generated by the switching process of the other phase. Conduction interference and leakage current, in addition, according to the current direction detected by the current detection device, the switching timing and pulse width of the upper and lower bridge arm switching elements of each phase can be changed, which can effectively compensate for the voltage offset caused by dead time and eliminate current distortion. The motor drive device provided by the present invention has a simple structure, and only needs to add a current detection device, which not only reduces the cost of eliminating conduction interference and leakage current, but also eliminates the voltage offset and current distortion caused by dead time. The structure of the present invention Simple, the change to the existing inverter circuit is small, only the current detection and carrier selection modules are added, and the impact on the cost is small.

Description of drawings

FIG. 1 is a schematic structural diagram of a motor drive device according to an embodiment of the present invention;

2 is a schematic structural diagram of a switch control device for switching elements of upper and lower bridge arms of an inverter circuit of a motor drive device in the prior art;

3 is a switching sequence diagram of the switching elements of the upper and lower bridge arms of the inverter circuit of the motor drive device in the prior art;

FIG. 4 is a timing chart of the transition of the terminal voltage of the U-phase and the V-phase of the motor drive device with respect to the current direction in the prior art;

5 is a schematic structural diagram of the switch control device for controlling the switch elements of the upper and lower bridge arms of the inverter circuit of the motor drive device according to the present invention;

6 is a switching sequence diagram of the switching elements of the upper and lower bridge arms of the inverter circuit of the motor drive device in the present invention;

7 is a schematic diagram of the waveforms of the three-phase switching waveform and the conduction interference and leakage current detection results of the motor drive device in the prior art;

8 is a schematic diagram of waveforms of three-phase switching waveforms and detection results of conduction interference and leakage current of the motor drive device of the present invention;

9 is a switching timing diagram of the switching elements of the upper and lower bridge arms of the inverter circuit of the motor drive device when the U-phase current is negative and the V-phase current is negative in the present invention;

10 is a switching timing diagram of the switching elements of the upper and lower bridge arms of the inverter circuit of the motor drive device when the U-phase current is positive and the V-phase current is positive in the present invention.

Description of reference numbers:

1-AC power supply; 2-rectification loop; 3-smoothing capacitor; 4a-first switch; 4b-first return diode; 5a-second switch; 5b-second return diode; 6a-third switch; 6b-th Three return diodes; 7a-fourth switch; 7b-fourth return diode; 8a-fifth switch; 8b-fifth return diode; 9a-sixth switch; 9b-sixth return diode; 10-motor; 11-control device; 12-current detection device; 20-triangle carrier generation module; 21-three-phase voltage command generation module; 22a-first comparator; 22b-second comparator; 22c-third comparator; 22d-fourth comparison 22e-fifth comparator; 22f-sixth comparator; 23a-first driver; 23b-second driver; 23c-third driver; 23d-fourth driver; 23e-fifth driver; 23f-sixth Driver; 30-saw wave generation module; 31-carrier selection module; 32-current direction detection module; 33-three-phase output voltage command generation module; 34a-seventh comparator; 34b-eighth comparator; 34c-ninth comparator; 34d-tenth comparator; 34e-eleventh comparator; 34f-twelfth comparator; 35a-seventh driver; 35b-eighth driver; 35c-ninth driver; 35d-tenth driver; 35e - eleventh drive; 35f - twelfth drive.

Detailed ways

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the described embodiments are some, but not all, of the embodiments of the present invention. The specific embodiments described herein are only used to explain the present invention, and are not intended to limit the present invention. It should be noted that the embodiments of the present invention and the features of the embodiments may be combined with each other under the condition of no conflict.

In the prior art, the switching elements of the upper and lower arms of the three-phase inverter circuit include a first switch 4a and a first return diode 4b arranged in parallel with it, a second switch 5a and a second return diode 5b arranged in parallel with it, and a third switch 6a. and the third return diode 6b arranged in parallel with it, the fourth switch 7a and the fourth return diode 7b arranged in parallel with it, the fifth switch 8a and the fifth return diode 8b arranged in parallel with it, the sixth switch 9a and its parallel arrangement The sixth freewheeling diode 9b; wherein, the first switch 4a, the first freewheeling diode 4b, the third switch 6a, the third freewheeling diode 6b, the fifth switch 8a, and the fifth freewheeling diode 8b constitute the upper bridge arm switching element, and the The two switches 5a, the second freewheeling diode 5b, the fourth switch 7a, the fourth freewheeling diode 7b, the sixth switch 9a, and the sixth freewheeling diode 9b constitute the lower arm switching element. The series connection point is connected to the U phase of the motor 10, the series connection point of the third switch 6a and the fourth switch 7a is connected to the V phase of the motor 10, and the series connection point of the fifth switch 8a and the sixth switch 9a is connected to the V phase of the motor 10. The W phase of the motor 10 is connected, and the control device structure of the upper and lower bridge arm switching elements in the inverter circuit is shown in Figure 2, including:

The three-phase voltage command generation module 21 is used to generate a three-phase AC voltage command; the three-phase voltage command includes a U-phase voltage command, a V-phase voltage command and a W-phase voltage command;

A triangular carrier generation module 20 is used to generate a triangular wave, and the triangular wave is a carrier wave of pulse output;

The comparator module is used to compare the three-phase voltage command and the carrier wave, and output the driving pulse of the switching element according to the comparison result;

The switching element driving module is used to drive and control the opening or closing of the switching element according to the driving pulse output by the comparator module;

The comparator module includes a first comparator 22a, a second comparator 22b, a third comparator 22c, a fourth comparator 22d, a fifth comparator 22e, and a sixth comparator 22f; the switching element driving module includes a A driver 23a, a second driver 23b, a third driver 23c, a fourth driver 23d, a fifth driver 23e, and a sixth driver 23f; the first comparator 22a, the first driver 23a, and the first switch 4a are connected in sequence; The two comparators 22b, the second driver 23b, and the second switch 5a are connected in sequence; the third comparator 22c, the third driver 23c, and the third switch 6a are connected in sequence; the fourth comparator 22d, the fourth driver 23d, and the fourth switch 7a connected in sequence; the fifth comparator 22e, the fifth driver 23e, and the fifth switch 8a are connected in sequence; the sixth comparator 22f, the sixth driver 23f, and the sixth switch 9a are connected in sequence;

In order to reduce the leakage current and conduction interference generated when the switching element in the inverter circuit is turned on or off, the triangular carrier generation module 20 generates two corresponding carriers, which are the first carrier and the second carrier respectively, and the second carrier Compared with the first carrier, the dead time is advanced. As shown in FIG. 2 , the first carrier is connected to the positive pole of the comparator corresponding to the switching element of the lower bridge arm, and the second carrier is connected to the comparison corresponding to the relevant switching element of the upper bridge arm. The three-phase voltage command generation module 21 is respectively connected to the positive pole of the comparator corresponding to the relevant switching element of the upper bridge arm, and the negative pole of the comparator corresponding to the switching element of the lower bridge arm, and accordingly, the shown in FIG. 3 can be obtained. The switching timing diagram of the switching elements of the upper and lower bridge arms of the inverter circuit of the motor drive device in the prior art, the upper part of Fig. 3 shows the time-lapse variation of the carrier wave and the output voltage command value in the PWM modulation, and the lower part shows the same as the three. With respect to the switching times of the first switches 4a to 9a corresponding to AC, it should be understood that the first switches 4a to 9a include the first switch 4a, the second switch 5a, the third switch 6a, the fourth switch 7a, and the fifth switch 8a , switches including the sixth switch 9a, and so on.

It can be seen from FIG. 3 that, for the U-phase voltage command, the corresponding first switches 4a and 5a will switch the first switch 4a and 5a according to the comparison result between the U-phase voltage command and the comparators of the first carrier and the second carrier during the period of time t3 to t6. On the other hand, the two switches 5a are turned on. On the other hand, the driver performs switching control so that the first switch 4a is turned on with a pulse width that provides a dead time for avoiding simultaneous turn-on. Similarly, for the output voltage of the V-phase, the corresponding third switch 6a and the fourth switch 7a switch the fourth switch between time t4 and t5 according to the comparison result between the V-phase voltage command and the comparators of the first carrier and the second carrier. 7a is turned on, on the other hand, the switching control is performed by the driver so that the third switch 6a is turned on with a pulse width provided with a dead time for avoiding simultaneous conduction; the W phase is fixed to a voltage of 0 in this interval, and the three-phase The AC voltage is used to drive the motor 10 as the voltage difference between the U-phase and the V-phase as the AC voltage for driving the motor 10 .

The upper part of FIG. 4 is the switching time of the first switch 4a to the sixth switch 9a corresponding to the lower part of FIG. 3 , and the lower part of FIG. 4 shows the change of the output voltage corresponding to the current direction of each phase. When the inverter circuit flows in the direction of the motor 10, the current direction is positive, and when the current flows from the motor 10 to the inverter circuit, the current direction is negative, and the output voltage of each phase is the positive side voltage of the DC part in FIG. ) and the negative side voltage (set to 0). As can be seen from Figure 4, in the dead time interval, when the current of each phase is positive, the output is the negative side voltage of 0, and when the current of each phase is negative , the output is the positive side voltage +Vdc. Taking the output voltage of the U direction as an example, when the current is positive, the output voltage is 0 during the period of t1~t8, but when the current is negative, the output voltage during the period of t3~t6 is 0, therefore, the setting of the dead time causes the average voltage of the output of each phase to change according to the change of the current direction, resulting in an offset of the output voltage in the dead time, and the motor 10 cannot apply the required voltage, resulting in a current bias. shift, resulting in current distortion.

The upper part of Fig. 7 is the switching state waveform of the U, V, W three-phase upper arm switching elements in the prior art, and the lower part of Fig. 7 is the prior art through LISN (Line Impedance Stabilization Network, line impedance stabilization network) Conducted disturbances detected during switching of switching elements and leakage currents of the motor.

The motor driving apparatus, method, air conditioner, and computer-readable storage medium according to the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Example 1

The present embodiment provides a motor driving device for driving a motor 10. The motor 10 is a three-phase motor, as shown in FIG. 1, including a pre-processing circuit and a three-phase inverter circuit. The pre-processing circuit It is used to input the AC power output by the power supply into a three-phase inverter circuit, and the three-phase inverter circuit includes the power supply line of the upper bridge arm and the power supply line of the lower bridge arm, and the power supply line of the upper bridge arm and the lower bridge arm. Between the upper bridge arm switching elements and the lower bridge arm switching elements connected in series in each phase, the connection point of the upper bridge arm switching element and the lower bridge arm switching element of each phase is connected to the motor 10, and also includes a control device 11, so The control device 11 is used to control the switching timing of the upper arm switching element and the lower arm switching element of each phase, and use the variation of the phase voltage of one phase of the motor 10 to offset the conduction disturbance and leakage caused by the variation of the phase voltage of the other phase. current. Specifically in this embodiment, the pre-processing circuit includes an AC power supply 1, a rectifier circuit 2, and a smoothing capacitor 3, which are used to temporarily convert the AC power output by the AC power supply 1 into a smooth DC power. The upper bridge arm switches The structure and connection manner of the element and the lower arm switch element are the same as those in the prior art, and will not be repeated here. The variation of the phase-to-phase voltage of the motor 10 offsets the conducted interference and leakage current caused by the variation of the phase-to-phase voltage of the other phase. The arm switching element or the lower arm switching element performs opposite switching actions at the same time. The opposite switching action means that in the upper arm or lower arm, the switching element of one phase is turned on, and the switching element of the other phase is turned off, as shown in the figure. 6, at time t10, the second switch 5a of the U-phase lower arm is turned on, and the fourth switch 7a of the V-phase lower arm is turned off. The detection results of the common mode interference and the leakage current of the motor 10 generated during switching are shown in FIG. 8 . Compared with FIG. 7 , the technical solution provided in this embodiment can significantly reduce the conduction interference generated by the switching element during the switching process and the motor 10 . The technical solution has nothing to do with the direction of the current, and is only related to the switching timing of the upper-bridge switching element and the lower-arm switching element.

Preferably, a current detection device 12 is provided between the power line of the lower bridge arm and the pre-processing circuit, and the current detection device 12 is used to detect the current output by each phase, and the control device 11 According to the current direction detected by the current detection device 12, the pulse width and time of the upper and lower arm switching elements of each phase are controlled, and the pulse width and time of the upper arm switching element and/or the lower arm switching element of each phase are compensated. voltage offset due to the dead time. Specifically, as shown in Figure 9 and Figure 10, by adjusting the pulse width and time of the upper arm switching element and the lower arm switching element of each phase, the voltage output of each phase when the current flows in different directions is changed. When the current direction is When it is negative, the output voltage at the dead time is the voltage on the high voltage side. When the current direction is positive, the output voltage at the dead time is the voltage on the low voltage side. The average output voltage of each phase does not depend on the current. changes in direction, that is, this setting compensates for the voltage offset caused by dead time, eliminating the current distortion caused by dead time in the prior art.

Specifically, the control device 11 includes:

The three-phase output voltage command generation module 33 is used to generate a three-phase voltage command; the three-phase voltage command includes a U-phase voltage command, a V-phase voltage command and a W-phase voltage command;

The current direction detection module 32 is used to judge the current flow direction according to the current detected by the current detection device 12, and input the current flow direction judgment result into the carrier selection module 31;

The saw wave generation module 30 is used for generating several groups of saw waves, and the several groups of the saw waves are the carrier waves of the pulse output;

The carrier selection module 31 is used to select and input the carrier of each phase from several groups of saw waves output by the saw wave generation module 30 according to the judgment result of the current direction detection module 32;

The comparator module is used to compare the three-phase voltage command and the carrier wave, and output the driving pulse of the switching element according to the comparison result;

The switching element driving module is used for driving and controlling the switching element to be turned on or off according to the driving pulse output by the comparator module.

Specifically in this embodiment, the comparator module includes a seventh comparator 34a, an eighth comparator 34b, a ninth comparator 34c, a tenth comparator 34d, an eleventh comparator 34e, and a twelfth comparator 34f ; The switching element driving module includes a seventh driver 35a, an eighth driver 35b, a ninth driver 35c, a tenth driver 35d, an eleventh driver 35e, and a twelfth driver 35f; the seventh comparator 34a, the seventh The driver 35a and the first switch 4a are connected in sequence; the eighth comparator 34b, the eighth driver 35b, and the second switch 5a are connected in sequence; the ninth comparator 34c, the ninth driver 35c, and the third switch 6a are connected in sequence; the tenth comparator 34d, the tenth driver 35d, and the fourth switch 7a are connected in sequence; the eleventh comparator 34e, the eleventh driver 35e, and the fifth switch 8a are connected in sequence; the twelfth comparator 34f, the twelfth driver 35f, the sixth switch 9a are connected in sequence;

In some of the embodiments, the saw wave generation module 30 is configured to generate 6 groups of carriers, which are:

the first carrier wave, the first carrier wave is a sawtooth wave with a positive slope with respect to time in one carrier cycle Tc;

a second carrier wave, the second carrier wave is a sawtooth wave having a negative slope with respect to time in one carrier cycle Tc;

a third carrier, the third carrier is a sawtooth wave whose time is advanced by the dead time relative to the first carrier;

the fourth carrier, the fourth carrier is a sawtooth wave whose time is advanced by the dead time relative to the second carrier;

a fifth carrier, the fifth carrier is a sawtooth wave whose time is delayed by the dead time relative to the first carrier;

a sixth carrier, the sixth carrier is a sawtooth wave whose time is delayed by the dead time relative to the second carrier;

Specifically, as shown in FIG. 6 , the carrier selection module 31 selects the sixth carrier and the second carrier in combination with the U-phase voltage command to generate the driving pulses of the first switch 4a and the second switch 5a, and selects the third carrier and the first carrier. Combined with the V-phase voltage command, the driving pulses of the third switch 6a and the fourth switch 7a are generated. It can be seen from FIG. 6 that in the U-phase, during the period from t0 to t1, the second switch 5a is turned on, and after the dead zone is delayed After time, the first switch 4a is turned on during the period t2 to t4, and then the dead time is delayed. At time t10, the second switch 5a is turned on; there are also multiple dead times in the V phase. At time t10, the fourth switch 5a is turned on. When the switch 7a is closed, at the same time, the switching elements between the two phases in the same bridge arm do opposite actions, which cancel out the conduction interference and leakage current generated during the switching action. The opposite switching action of U-phase and V-phase at the same time reduces the overall conduction interference and leakage current by about half, which has a significant effect. It should be understood that this effect is achieved regardless of the direction of the current. It should be noted that the carrier waveforms used in the present invention are not limited to the above-mentioned 6 types of carriers, and other carrier waveforms can also be used, so that the phase voltage change of one phase and the phase voltage change of another phase can be reversed at the same time.

In another embodiment, when the U-phase current direction is positive, the second carrier, the fourth carrier and the U-phase voltage command are selected to generate driving pulses for the first switch 4a and the second switch 5a. When the U-phase current direction is When it is negative, select the 6th carrier, the 2nd carrier and the U-phase voltage command to generate the driving pulse of the first switch 4a and the second switch 5a; when the V-phase current direction is positive, select the 1st carrier, the 5th carrier and the V The phase voltage command is combined to generate the drive pulses of the third switch 6a and the fourth switch 7a. When the V-phase current direction is negative, the third carrier and the first carrier are selected in combination with the V-phase voltage command to generate the third switch 6a and the fourth switch. 7a driving pulse, in this case, the corresponding output voltage is shown in Figure 9 and Figure 10. It can be seen that when the U-phase and V-phase current directions are both negative, the output voltage at the dead time is high. The voltage on the voltage side, when the U-phase and V-phase current directions are both positive, the output voltage at the dead time is the voltage on the low voltage side, and the average output voltage of each phase does not vary according to the current direction. That is, the setting compensates for the voltage offset caused by the dead time, and eliminates the current distortion caused by the dead time in the prior art. It can be seen that regardless of the direction of the current flowing in the motor 10, it can be The output voltage is not affected by the dead time generated by the switching of the upper and lower bridge arms of each phase. At the same time, at the time t10, the reverse switching operation of the upper bridge arm switching element or the lower bridge arm switching element also occurs, effectively The transmission interference and leakage current caused by the switching action are reduced.

With the above structure, the motor driving device of the present invention can reduce conduction disturbance and leakage current with a simple structure, and can compensate for voltage offset caused by dead time, so that no current offset occurs when the motor 10 is driven.

Example 2

This embodiment discloses a motor driving method, and the motor driving method adopts the motor driving device described in Embodiment 1.

The motor driving method is used to drive the motor 10, and the motor 10 is a three-phase motor, and the driving method includes: controlling the switching timing of the upper arm switching element and the lower arm switching element of each phase of the motor 10, in a carrier wave. During the period Tc, there is at least one moment in which the switching elements of the upper arm or the switching elements of the lower arm between different two phases in the motor 10 perform opposite switching actions at the same time. The opposite switching actions refer to the upper arm or the lower arm In the arm, the switching element of one phase is turned on, and the switching element of the other phase is turned off, and the change of the phase-to-phase voltage of the motor 10 is used to offset the conduction interference and leakage current caused by the change of the phase-to-phase voltage of the other phase, as shown in Figure 6, At time t10, the second switch 5a of the U-phase lower arm is turned on, and the fourth switch 7a of the V-phase lower arm is turned off. Through the synchronous opening and closing operations between the two phases, the switching elements generated during switching are reduced. Common mode interference and the leakage current of the motor 10, the detection results are shown in Figure 8. Compared with Figure 7, the technical solution provided by this embodiment can significantly reduce the conduction interference generated by the switching element during the switching process and the leakage current of the motor 10. The technical solution has nothing to do with the direction of the current, and is only related to the switching timings of the upper-arm switching element and the lower-arm switching element.

As a preferred embodiment, the driving method further includes: detecting the current direction of each phase of the motor 10, controlling the pulse width and time of the upper arm switching element and the lower arm switching element of each phase according to the current direction, and compensating for each The voltage offset due to the dead time of the high-side switching element and/or the low-side switching element of the phase. Specifically, as shown in Figure 9 and Figure 10, by adjusting the pulse width and time of the upper arm switching element and the lower arm switching element of each phase, the voltage output when the current of each phase flows in different directions is changed. When the V-phase current directions are both negative, the output voltage at the dead time is the voltage on the high-voltage side. When the U-phase and V-phase current directions are both positive, the output voltage at the dead time is the low-voltage side voltage. The average voltage of the output of each phase does not change according to the change of the current direction, that is, this setting compensates for the voltage offset caused by the dead time, eliminating the current distortion caused by the dead time in the prior art .

Specifically, in this embodiment, the switching timings of the upper arm switching element and the lower arm switching element of each phase are controlled according to the change of the carrier wave, or the upper arm switching element and the lower arm switching element of each phase are selected according to the current direction The switching element drives the carrier required by the pulse, and controls the pulse width and time of the upper and lower switching elements of each phase according to the carrier. Controlling switch timing and/or pulse width based on the carrier is simple and effective, with limited impact on cost.

As an embodiment of the present invention, the carrier wave is a saw-shaped carrier wave, including:

the first carrier wave, the first carrier wave is a sawtooth wave with a positive slope with respect to time in one carrier cycle Tc;

a second carrier wave, the second carrier wave is a sawtooth wave having a negative slope with respect to time in one carrier cycle Tc;

a third carrier, the third carrier is a sawtooth wave whose time is advanced by the dead time relative to the first carrier;

the fourth carrier, the fourth carrier is a sawtooth wave whose time is advanced by the dead time relative to the second carrier;

a fifth carrier, the fifth carrier is a sawtooth wave whose time is delayed by the dead time relative to the first carrier;

The sixth carrier is a sawtooth wave whose time is delayed by the dead time with respect to the second carrier.

In the present embodiment, a sawtooth wave having a period of Tc and an amplitude of Vc is used as the carrier of the PWM drive pulse for controlling the switches, and the voltages of the first to sixth switches 4a to 9a are determined by comparison with the output three-phase voltages. Switching time, through the change of multiple carrier waves, can control the pulse width and/or switching timing of each phase of the motor 10, which can effectively reduce the conduction interference and leakage current when the switching element performs the switching action, and can also reduce the dead time. Output voltage deviation, eliminating current distortion.

In a specific embodiment, the motor 10 includes U-phase, V-phase, and W-phase, and the upper bridge arms of U-phase, V-phase, and W-phase are sequentially provided with a first switch 4a, a third switch 6a, and a fifth switch 8a. The lower bridge arm is set with the second switch 5a, the fourth switch 7a and the sixth switch 9a in sequence, the sixth carrier is selected as the driving pulse carrier of the first switch 4a, and the second carrier is used as the driving pulse carrier of the second switch 5a; the third carrier is selected as the driving pulse carrier of the first switch 4a. The carrier is used as the driving pulse carrier of the third switch 6a, and the first carrier is used as the driving pulse carrier of the fourth switch 7a; it can be seen from Figure 6 that in the U phase, during the period from t0 to t1, the second switch 5a is turned on, After delaying the dead time, the first switch 4a is turned on during the period from t2 to t4, and then the dead time is delayed again. At t10, the second switch 5a is turned on; there are also multiple dead times in the V phase, and at t10 At the moment, the fourth switch 7a is closed, and at the same moment, the switching elements between the two phases in the same bridge arm do opposite actions, which cancel out the conduction interference and leakage current generated during the switching action. The voltage is always 0, which is not specifically limited here. The specific test results are shown in Figure 8. Compared with Figure 7, it can be seen that the opposite switching actions of the U-phase and the V-phase at the same time reduce the overall conduction interference and leakage current by about half, which has a significant effect. It needs to be explained , the effect is achieved regardless of the direction of the current.

In another embodiment, the motor 10 includes a U-phase, a V-phase, and a W-phase. The upper bridge arms of the U-phase, V-phase, and W-phase are sequentially provided with a first switch 4a, a third switch 6a, and a fifth switch 8a. The bridge arm is set with the second switch 5a, the fourth switch 7a, and the sixth switch 9a in turn. When the U-phase and V-phase current directions are both positive, the second carrier is selected as the driving pulse carrier of the first switch 4a, and the fourth carrier is selected as the driving pulse carrier of the first switch 4a. For the driving pulse carrier of the second switch 5a, select the first carrier as the driving pulse carrier of the third switch 6a, and the fifth carrier as the driving pulse carrier of the fourth switch 7a; when the U-phase and V-phase current directions are both negative, select The sixth carrier is used as the driving pulse carrier for the first switch 4a, the second carrier is used as the driving pulse carrier for the second switch 5a, the third carrier is selected as the driving pulse carrier for the third switch 6a, and the first carrier is selected as the driving pulse for the fourth switch 7a. Pulse carrier; in this case, the corresponding output voltage is shown in Figure 9 and Figure 10. It can be seen that when the U-phase and V-phase current directions are both negative, the output voltage at the dead time is the high voltage side When the U-phase and V-phase current directions are both positive, the output voltage at the dead time is the voltage on the low voltage side, and the average output voltage of each phase does not change according to the current direction. That is, this setting compensates for the voltage offset caused by the dead time and eliminates the current distortion caused by the dead time in the prior art. Since the output voltage of the W phase is always 0 during this process, no specific limitation is made here. . It can be seen that regardless of the direction of the current flowing in the motor 10, the output voltage can be output that is not affected by the dead time caused by the switching of the upper and lower arms of each phase. At the same time, the upper arm switch also occurs at t10. The reverse switching operation of the element or the lower arm switching element effectively reduces the transmission interference and leakage current caused by the switching action.

In this embodiment, the selection scheme of one of the optional carriers is shown in Table 1 and Table 2,

Table 1 U-phase switching element drive pulse carrier selection table

U-phase current direction first switch 4a second switch 5a just 2nd carrier 4th carrier burden 6th carrier 2nd carrier

Table 2 V-phase switching element drive pulse carrier selection table

V-phase current direction third switch 6a Fourth switch 7a just 1st carrier 5th carrier burden 3rd carrier 1st carrier

It can be seen from Figure 10 that when the U-phase and V-phase current directions are positive, the output voltage is the voltage on the low-voltage side during the dead time of switching between the upper and lower arms of the switching elements. When the direction of the phase current is negative, the output voltage is the voltage of the high voltage side during the dead time of switching between the upper and lower arms of the switching element. The switches of the phases perform opposite switching actions, which effectively reduces the conduction interference and leakage current generated during the switching process.

Example 3

This embodiment discloses an air conditioner, and the air conditioner includes the motor driving device described in Embodiment 2.

The air conditioner disclosed in this embodiment includes a computer-readable storage medium storing a computer program and a processor, and when the computer program is read and executed by the processor, the motor drive as described in Embodiment 2 is implemented method.

The air conditioner and the motor driving method described in Embodiment 1 have the same advantages over the prior art, which will not be repeated here.

Example 4

This embodiment discloses a computer-readable storage medium. The computer-readable storage medium stores a computer program, and when the computer program is read and executed by a processor, the motor driving method described in Embodiment 2 is implemented.

Although the present invention is disclosed above, the present invention is not limited thereto. In the description of this specification, reference to the terms "one embodiment," "some embodiments," "exemplary embodiment," "example," "specific example," or "some examples", etc., is meant to incorporate the embodiments A particular feature, structure, material, or characteristic described by an example or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be based on the scope defined by the claims.

Claims (12)

1. A motor driving device is used for driving a motor (10), the motor (10) is a three-phase motor, and is characterized by comprising a preceding stage processing circuit and a three-phase inverter circuit, the preceding stage processing circuit is used for inputting alternating current output by a power supply into the three-phase inverter circuit after being directly fluidized, the three-phase inverter circuit comprises an upper bridge arm power line, a lower bridge arm power line, an upper bridge arm switching element and a lower bridge arm switching element which are connected in series according to each phase between the upper bridge arm power line and the lower bridge arm power line, the connection point of the upper bridge arm switching element and the lower bridge arm switching element of each phase is connected with the motor (10), the motor driving device also comprises a control device (11), the control device (11) is used for controlling the switching timing of the upper bridge arm switching element and the lower bridge arm switching element of each phase, and the change of the voltage of one phase of the motor (10) is used for counteracting conduction interference and leakage current caused by the change of the phase voltage of the other phase, the method for counteracting the conduction interference and the leakage current caused by the phase voltage change of one phase of the motor (10) by using the change of the phase voltage of the other phase means that at least one moment in one carrier cycle Tc, the upper bridge arm switching elements or the lower bridge arm switching elements between different two phases simultaneously perform opposite switching actions, and the opposite switching actions are that the switching elements of one phase are opened and the switching elements of the other phase are closed in the upper bridge arm or the lower bridge arm.

2. The motor drive device according to claim 1, wherein a current detection device (12) is provided between the lower arm power supply line and the preceding stage processing circuit, the current detection device (12) is configured to detect a current output from each phase, and the control device (11) controls a pulse width and a pulse time of the upper arm switching element and the lower arm switching element of each phase according to a current direction detected by the current detection device (12) to compensate for a voltage deviation caused by a dead time of the upper arm switching element and/or the lower arm switching element of each phase.

3. A motor drive as claimed in claim 2, characterized in that said control means (11) comprise:

the three-phase output voltage instruction generating module (33) is used for generating three-phase voltage instructions; the three-phase voltage command comprises a U-phase voltage command, a V-phase voltage command and a W-phase voltage command;

a current direction detection module (32) for judging the current flow direction according to the current detected by the current detection device (12) and inputting the current flow direction judgment result into the carrier selection module (31);

the saw wave generating module (30) is used for generating a plurality of groups of saw-shaped carrier waves, and the saw waves are carrier waves output by pulses;

the carrier selection module (31) is used for selecting and inputting carriers of each phase from a plurality of groups of saw waves output by the saw wave generation module (30) according to the judgment result of the current direction detection module (32);

the comparator module is used for comparing the three-phase voltage command with the carrier wave and outputting a driving pulse of the switching element according to a comparison result;

and the switching element driving module is used for driving and controlling the switching element to be switched on or switched off according to the driving pulse output by the comparator module.

4. A motor driving method for driving a motor driving device according to claim 1, characterized by comprising: the switching timing of the upper arm switching elements and the lower arm switching elements of each phase of the motor (10) is controlled, and at least one moment in a carrier cycle Tc, the upper arm switching elements or the lower arm switching elements between different two phases in the motor (10) simultaneously perform opposite switching actions.

5. The motor driving method according to claim 4, wherein the current direction of each phase of the motor (10) is detected, and the pulse widths and the times of the upper arm switching elements and the lower arm switching elements of each phase are controlled according to the current direction to compensate for a voltage deviation due to a dead time of the upper arm switching elements and/or the lower arm switching elements of each phase.

6. The motor driving method according to claim 4 or 5, wherein switching timings of the upper arm switching elements and the lower arm switching elements of the respective phases are controlled in accordance with a change in the carrier wave.

7. The motor driving method according to claim 4 or 5, wherein a carrier wave required for driving the pulses of the upper arm switching element and the lower arm switching element of each phase is selected according to a current direction, and pulse widths and times of the upper arm switching element and the lower arm switching element of each phase are controlled according to the carrier wave.

8. The motor driving method of claim 6, wherein the carrier is a saw-shaped carrier comprising:

a 1 st carrier wave, the 1 st carrier wave being a sawtooth wave having a positive slope with respect to time in one carrier period Tc;

a 2 nd carrier wave, the 2 nd carrier wave being a sawtooth wave having a negative slope with respect to time in one carrier period Tc;

a 3 rd carrier wave, the 3 rd carrier wave being a sawtooth wave that advances time by a dead time relative to a 1 st carrier wave;

a 4 th carrier wave, the 4 th carrier wave being a sawtooth wave that advances time by a dead time relative to a 2 nd carrier wave;

a 5 th carrier wave, the 5 th carrier wave being a sawtooth wave delayed in time by a dead time with respect to the 1 st carrier wave;

a 6 th carrier wave, the 6 th carrier wave being a sawtooth wave delayed in time by a dead time with respect to the 2 nd carrier wave.

9. The motor driving method according to claim 8, wherein the motor (10) includes a U-phase, a V-phase, and a W-phase, and the U-phase, the V-phase, and the W-phase upper arm are sequentially provided with a first switch (4 a), a third switch (6 a), and a fifth switch (8 a), and the lower arm is sequentially provided with a second switch (5 a), a fourth switch (7 a), and a sixth switch (9 a), and the 6 th carrier is selected as a driving pulse carrier of the first switch (4 a), and the 2 nd carrier is selected as a driving pulse carrier of the second switch (5 a); the 3 rd carrier wave is selected as the driving pulse carrier wave of the third switch (6 a), and the 1 st carrier wave is selected as the driving pulse carrier wave of the fourth switch (7 a).

10. The motor driving method according to claim 8, wherein the motor (10) includes a U-phase, a V-phase, and a W-phase, the upper arm of the U-phase, the V-phase, and the W-phase is provided with a first switch (4 a), a third switch (6 a), and a fifth switch (8 a) in sequence, the lower arm is provided with a second switch (5 a), a fourth switch (7 a), and a sixth switch (9 a) in sequence, when the U-phase and the V-phase current directions are both positive, the 2 nd carrier wave is selected as the driving pulse carrier wave of the first switch (4 a), the 4 th carrier wave is selected as the driving pulse carrier wave of the second switch (5 a), the 1 st carrier wave is selected as the driving pulse carrier wave of the third switch (6 a), and the 5 th carrier wave is selected as the driving pulse carrier wave of the fourth switch (7 a); when the current directions of the U-phase and the V-phase are both negative, the 6 th carrier wave is selected as the driving pulse carrier wave of the first switch (4 a), the 2 nd carrier wave is selected as the driving pulse carrier wave of the second switch (5 a), the 3 rd carrier wave is selected as the driving pulse carrier wave of the third switch (6 a), and the 1 st carrier wave is selected as the driving pulse carrier wave of the fourth switch (7 a).

11. An air conditioner comprising a computer-readable storage medium storing a computer program and a processor, the computer program being read and executed by the processor to implement the motor driving method according to claims 4 to 10.

12. A computer-readable storage medium, characterized in that it stores a computer program which, when read and executed by a processor, implements the motor driving method according to claims 4-10.

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