CN111835238A - Multi-axis motor control system and method - Google Patents

Abstract

The invention relates to a multi-axis motor control system and a method, wherein a control command, a pulse width modulation period setting and a pulse width modulation command updating time setting of a multi-axis motor are generated to a multi-axis motor driver, a pulse width modulation carrier module receives the pulse width modulation period setting and the pulse width modulation command updating time setting, then generates a first group of carrier signals and a second group of carrier signals with a phase difference of 180 degrees, and the pulse width modulation command updating time of the first group of carrier signals and the pulse width modulation command updating time of the second group of carrier signals are synchronous, so that digital delay is avoided and leakage current is reduced.

Description

Multi-axis motor control system and method

technical field

The present invention relates to a multi-axis motor control system and method.

Background technique

Usually, when a Pulse Width Modulation (Pulse Width Modulation) inverter drives a motor, a high-frequency leakage current will be generated due to the switching of the PWM, and the higher the carrier frequency, the more obvious the leakage current. The main reason is that the common mode When the voltage changes, high-frequency leakage current is generated. The current flows from the motor winding to the ground through the motor frame. Sometimes its peak value can reach the rated value, which will cause serious problems such as electromagnetic interference and inverter current malfunction. It will affect the life of the motor.

In addition, since there are multiple parasitic capacitances to ground (FG) in the overall circuit of the driver, during the motor control process, the switching frequency of the ON-OFF signal of the inverter switch is equivalent to the frequency of charging and discharging the parasitic capacitance of the DC BUS voltage. In the process of high frequency charging and discharging of parasitic capacitance, the generated alternating current signal is regarded as leakage current. In the multi-axis simultaneous motion process of the all-in-one driver, the inverter switches of each axis have a higher chance of being designed in a synchronous manner, resulting in the accumulation of leakage currents, resulting in product reliability problems.

Generally, to solve the leakage problem caused by high-frequency charging and discharging of parasitic capacitance, the common methods are as follows: 1. Use additional hardware devices (circuits) to deal with leakage current, 2. Adjust the pulse width modulation output phase of single-axis three-phase UVW, 3. .Adjust the PWM output phase difference of different axes.

The technologies of using additional hardware devices (circuits) to process leakage current include: Publication number: CN105024620A A circuit is disclosed in the application to measure the leakage current of the capacitor in the LC filter circuit, sample and amplify the leakage current signal, and use the leakage current to measure the leakage current. Compensation back to the drive circuit, or a common mode transformer structure disclosed in Taiwan Patent (TW449955B), which functions like a damping resistor. will cause leakage current.

The technology for adjusting the PWM output phase of a single-axis three-phase UVW is: Japanese patent (JP2016214038A) is designed to delay the triggering of the V and W phases when the U-phase outputs the PWM signal to achieve the effect of staggered switching. Or the technical feature of the Japanese patent (JP2005051959A) is to use switch components to control the voltage output timing of the UVW three-phase, so as to avoid switching multiple phases at the same time.

The technology of adjusting the output phase difference of pulse width modulation of different axes is: Japanese patent (JP2007336634A) The technical feature is that the number of axes of the multi-axis drive is divided into two groups, if the total number of axes is even, it will be divided equally, if the total number of axes is odd Then the difference between the two groups is 1 axis at most, and the two groups of axes are designed with a pulse width modulation phase difference of 180 degrees to achieve the effect of reducing leakage. Or the technical feature of the US patent (US20190363600A1) is that the number of axes of the multi-axis drive is divided into M groups, and the PWM phase difference of each group of axes is designed to be 360/M degrees (that is, the difference between two axes is 180 degrees, and the difference between three axes is 120 degrees). The effect of reducing leakage.

Therefore, no matter through software or hardware, as long as the inverter switching signals of each axis are designed to have a phase difference with each other, the leakage current can be reduced by adjusting the output phase difference of the pulse width modulation of different axes, so that the AC signals can cancel each other in the system. , the leakage problem can be effectively suppressed. However, the phase difference of the inverter switch signals of each axis may cause digital delay, which will affect the motor control results and cause processing problems.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a multi-axis motor control system, which can solve the problem of product reliability caused by the accumulation of leakage current during the motor control process, and can also prevent the digital signal that may be caused by the phase difference of the inverter switch signals of each axis. Delay.

In order to solve the above-mentioned technical problems, the present invention adopts the following technical solutions: a multi-axis motor control system, which is applied to the drive control of multiple motors, and the multiple motors are divided into two groups, which are respectively a first group of motors and a second group of motors, The control system includes:

a control device, which is used to generate a control command for the multi-axis motor, a pulse width modulation period setting and a pulse width modulation command update time setting;

Multi-axis motor drive, which includes:

a control module, which generates a first set of voltage commands and a second set of voltage commands after receiving the control command;

A pulse width modulation carrier module, which generates a first group of carrier signals and a second group of carrier signals after receiving the pulse width modulation period setting, and the phase difference between the first group of carrier signals and the second group of carrier signals is 180 and synchronizing the pulse width modulation command update time of the first group of carrier signals and the second group of carrier signals according to the pulse width modulation command update time setting;

a first group of comparators, which generate a first group of modulated voltages after receiving the first group of voltage commands and the first group of carrier signals;

a second group of comparators, which generate a second group of modulated voltages after receiving the second group of voltage commands and the second group of carrier signals;

A first group of PWM inverters, which receive the first group of modulated voltages and generate a first group of AC voltages, and transmit the first group of AC voltages to a first group of motors to drive the first group of motors ;

A second group of PWM inverters, which receive the second group of modulated voltages to generate a second group of AC voltages, and transmit the second group of AC voltages to the second group of motors to drive the second group of motors .

In another preferred manner, when the total number of the motors is an even number, the motors are evenly distributed into the first group of motors and the second group of motors with equal numbers.

In another preferred manner, when the total number of motors is an odd number, the motors are allocated into a first group of motors and a second group of motors whose number of motors differs by one.

In another preferred manner, the control command is used to control the motor to perform a required corresponding action.

In another preferred manner, the PWM carrier module includes a PWM carrier generation component, a control component, and a PWM command update circuit; the control component is responsible for controlling the phase difference setting, pulse width between the two groups of carriers Modulation cycle setting and pulse width modulation command update time setting, the pulse width modulation carrier generation component generates the first group of carrier signals and the first set of carrier signals according to the phase difference setting provided by the control component and the received pulse width modulation cycle setting. For two groups of carrier signals, the PWM command update circuit performs synchronous PWM command update according to the PWM command update time setting received by the control component.

The present invention also provides a multi-axis motor control method, which is applied to the drive control of multiple motors. The multiple motors are divided into two groups, which are a first group of motors and a second group of motors. The method includes:

The multi-axis motor driver includes a control module, a pulse-width modulation carrier module, a first a group of comparators, a second group of comparators, a first group of PWM inverters, and a second group of PWM inverters;

The control module generates a first set of voltage commands and a second set of voltage commands after receiving the control command; and after the PWM carrier module receives the PWM period setting and the PWM command update time setting Generate a first group of carrier signals and a second group of carrier signals, the phase difference between the first group of carrier signals and the second group of carrier signals is 180 degrees, and according to the pulse width modulation command update time setting The first group of carrier signals is synchronized with the pulse width modulation command update time of the second group of carrier signals;

After receiving the first group of voltage commands and the first group of carrier signals through the first group of comparators, a first group of modulated voltages is generated, and the second group of comparators receives the second group of voltage commands and the first group of modulation voltages. generating a second group of modulated voltages after the second group of carrier signals;

and the first group of PWM inverters and the second group of PWM inverters respectively receive the first group of modulated voltages and the second group of modulated voltages to generate AC voltages and drive the first group of modulated voltages respectively. One set of motors and the second set of motors.

In another preferred manner, when the total number of the motors is an even number, the motors are evenly distributed into the first group of motors and the second group of motors with equal numbers.

In another preferred manner, when the total number of the motors is an odd number, the motors are allocated into a first group of motors and a second group of motors whose numbers differ by one.

In another preferred manner, the control command is used to control the motor to perform a required corresponding action.

In another preferred manner, the PWM carrier module includes a PWM carrier generation component, a control component, and a PWM command update circuit; the control component is responsible for controlling the phase difference setting, pulse width between the two groups of carriers The modulation period setting and the pulse width modulation command update time setting, the pulse width modulation carrier generation component generates the first group according to the phase difference setting provided by the control component and the received pulse width modulation period setting For the carrier signal and the second group of carrier signals, the pulse width modulation command update circuit performs synchronous pulse width modulation command update according to the pulse width modulation command update time setting received from the control component.

The beneficial effect of the present invention is that: the system and method of the present invention, through the design of 180-degree phase difference between the pulse width modulated carriers of each axis, allows the alternating current signals generated by the high frequency charging and discharging of the inverter switch to cancel each other in the system. It can effectively reduce the leakage problem of the multi-axis simultaneous movement of the all-in-one driver, and is designed with a method of synchronizing the update time of the PWM command to avoid digital delay.

Description of drawings

FIG. 1 is a schematic diagram of a multi-axis motor control system.

FIG. 2 is a schematic diagram of a pulse width modulation carrier module.

FIG. 3 is a schematic diagram of the PWM carrier and inverter switching signals of two axes simultaneously moving;

In the figure, 100-control device; 101-control command; 102-pulse width modulation cycle setting; 103-pulse width modulation command update time setting; 200-multi-axis motor driver; 210-control module; 211-first group Voltage command; 212-the second group of voltage commands; 220-pulse width modulation carrier module; 221-the first group of carrier signals; 222-the second group of carrier signals; 230-the first group of comparators; 231-the first group of modulation Voltage; 240- the second group of comparators; 241- the second group of modulated voltages; 250- the first group of PWM inverters; 251- the first group of AC voltages; 260- the second group of PWM inverters ; 261- the second group of AC voltage; 310- the first group of motors; 320- the second group of motors; 410- control components; 420- pulse width modulation carrier generation components; - Inverter switch signal.

Detailed ways

The present invention is described in detail below in conjunction with the embodiments shown in the accompanying drawings:

As shown in Figure 1, the multi-axis motor control system is applied to the drive control of multiple motors (that is, two or more motors). A set of motors 310 and a second set of motors 320 . When the total number of the motors is an odd number, the motors are allocated into the first group of motors 310 and the second group of motors 320 whose numbers differ by one.

The multi-axis motor control system includes: a control device 100 for generating a control command 101 for the multi-axis motor, a pulse width modulation period setting 102 and a pulse width modulation command update time setting 103, and the control command 101 is used to control the motor (The first group of motors 310 and the second group of motors 320 ) perform the required corresponding actions. Among them, the first group of motors 310 and the second group of motors 320 change the rotational speed, position or torque, etc. according to the control command 101 .

The multi-axis motor driver 200 includes: a control module 210 for generating a first set of voltage commands 211 and a second set of voltage commands 212 after receiving the control command 101; a pulse width modulation carrier module 220 , which is used to generate the first group of carrier signals 221 and the second group of carrier signals 222 after receiving the PWM period setting 102, the phase difference between the first group of carrier signals 221 and the second group of carrier signals 222 is 180 degrees, and according to The PWM command update time setting 103 synchronizes the PWM command update time of the first group of carrier signals 221 and the second group of carrier signals 222; the first group of comparators 230 receives the first group of voltage commands 211 and the first group of The carrier signal 221 generates the first set of modulated voltages 231; the second set of comparators 240 receives the second set of voltage commands 212 and the second set of carrier signals 222 to generate the second set of modulated voltages 241 (the above-mentioned first set of comparators 230 and the second set of comparators 240 are electronic components (ie Comparator) that are often used in general circuits, and are commercially available and conventional, and the compared signals are the voltage commands and carrier signals mentioned later); first The group of PWM inverters 250 receives the first group of modulated voltages 231 to generate the first group of AC voltages 251, and transmits the first group of AC voltages 251 to the first group of motors 310 for driving the first group of motors 310; The two sets of PWM inverters 260 receive the second set of modulated voltages 241 to generate a second set of AC voltages 261 , and transmit the second set of AC voltages 261 to the second set of motors 320 for driving the second set of motors 320 .

The control device 100 can be a controller of a processing machine (not shown in the figure), a desktop computer, a notebook computer, a smart phone, or a remote server, etc., and the control device 100 and the multi-axis motor driver 200 can be wired or connect wirelessly.

As shown in FIG. 2 , the PWM carrier module 220 includes a PWM carrier generation component 420 , a control component 410 , and a PWM command update circuit 430 . The control component 410 is responsible for controlling the setting of the phase difference between the two groups of carriers, the setting of the period of the pulse width modulation and the setting of the update time of the pulse width modulation command.

The PWM carrier generation component 420 generates the first set of carrier signals 221 and the second set of carrier signals 222 according to the phase difference setting provided by the control component 410 and the PWM period setting 102 received by the control component 410, so that the first set of carrier signals 221 and 222 are generated. The phase difference between the signal 221 and the second group of carrier signals 222 is 180 degrees; and the PWM command update circuit 430 sets 103 the synchronous PWM command update time according to the PWM command update time received by the control component 410 .

Regarding the update time of the synchronous PWM command, the phase difference design method is used to coordinate the update time of the synchronous PWM command to avoid digital delay. As shown in Figure 3, the schematic diagram of the PWM carrier and the inverting switching signal of the two-axis co-moving. The black dotted line represents the command update time of the inverter switching signals 252 and 262 (respectively the inverter switching signals of the first group of PWM inverters 250 and the second group of PWM inverters 260 ), that is, the PWM command The update time setting 103 is designed so that the pulse width modulated carrier (the first group of carrier signals 221 and the second group of carrier signals 222 ) will update the signal when counting up to the peak and down to the trough. Therefore, the first group of motors 310 and the first group of The two sets of motors 320 acquire data at the same time, and no digital delay is generated. In addition, the difference between the inverter switching signals 252 and 262 is only updated in the first half or the second half of the cycle, and does not affect the signal itself. In addition, because the phase difference between the first group of carrier signals 221 and the second group of carrier signals 222 is 180 degrees, the inverter switches of the first group of PWM inverters 250 and the second group of PWM inverters 260 The ON-OFF time of the signal will be staggered, so that the AC signals generated by the charging and discharging of the inverter switch can cancel each other in the system, reducing the leakage current problem.

To sum up the above, the multi-axis motor control method is as follows: the control device 100 generates a control command 101 for the multi-axis motor, the pulse width modulation period setting 102 and the pulse width modulation command update time setting 103 to the multi-axis motor driver 200. The control module 210 in the motor driver 200 generates the first set of voltage commands 211 and the second set of voltage commands 212 after receiving the control command 101 ; and the PWM carrier module 220 receives the PWM cycle setting 102 and the PWM command update time After setting 103, a first group of carrier signals 221 and a second group of carrier signals 222 are generated. The phase difference between the first group of carrier signals 221 and the second group of carrier signals 222 is 180 degrees, and the time is updated according to the PWM command. Set 103 Synchronize the update time of the pulse width modulation command of the first group of carrier signals 221 and the second group of carrier signals 222; then receive the voltage commands (211 and 212) and the carrier signal through the first group of comparators 250 and the second group of comparators 260 respectively ( 221 and 222 ) and then generate modulated voltages ( 231 and 241 ); and the first group of PWM inverters 250 and the second group of PWM inverters 260 respectively receive the modulated voltages and then generate AC voltages ( 251 and 241 ) 261) and thereby drive the first set of motors 310 and the second set of motors 320 respectively.

In this case, the technical design of synchronous PWM update time and PWM carrier phase difference can make the inverter switching signals of each axis (the first group of motors 310 and the second group of motors 320 ) have a phase difference relationship with each other, so that the AC signal Can offset each other in the system, effectively suppress the leakage problem, and because the update time of the pulse width modulation command of each axis is the same, it will not cause digital delay and affect the motor control results.

The advantage of this case is that, through the drive technology of this case, the PWM carriers of each axis have a phase difference of 180 degrees with each other, so that the AC signals generated by the high-frequency switching of the inverter switches can be offset in the system, effectively reducing the multi-combination The leakage problem when a driver performs multi-axis simultaneous motion, and the method of synchronizing the pulse width modulation carrier update time is designed, so that the phase difference design will not cause digital delay and affect the motor control results.

The above-mentioned embodiments are only intended to illustrate the technical concept and characteristics of the present invention, and the purpose is to enable those skilled in the art to understand the content of the present invention and implement them accordingly, and cannot limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be included within the protection scope of the present invention.

Claims (10)

1. The utility model provides a multiaxis motor control system, is applied to the drive control of a plurality of motors, and a plurality of motors divide into two sets ofly, is first group motor and second group motor respectively, its characterized in that: the control system includes:

a control device for generating a control command, a pulse width modulation period setting and a pulse width modulation command update time setting for the multi-axis motor;

multiple-shaft motor driver comprising

The control module receives the control command and then generates a first group of voltage commands and a second group of voltage commands;

the pulse width modulation carrier module receives the pulse width modulation period setting and then generates a first group of carrier signals and a second group of carrier signals, the phase difference between the first group of carrier signals and the second group of carrier signals is 180 degrees, and the pulse width modulation command updating time of the first group of carrier signals and the pulse width modulation command updating time of the second group of carrier signals are synchronous according to the pulse width modulation command updating time setting;

a first set of comparators for generating a first set of modulation voltages upon receiving the first set of voltage commands and the first set of carrier signals;

a second set of comparators for generating a second set of modulation voltages upon receiving the second set of voltage commands and the second set of carrier signals;

a first PWM inverter for receiving the first modulated voltage and generating a first AC voltage, and transmitting the first AC voltage to a first motor to drive the first motor;

and the second group of pulse width modulation inverters generate a second group of alternating voltages after receiving the second group of modulation voltages and transmit the second group of alternating voltages to a second group of motors so as to drive the second group of motors.

2. The multi-axis motor control system of claim 1, wherein: when the total number of the motors is even, the motors are evenly distributed into a first group of motors and a second group of motors which are equal in number.

3. The multi-axis motor control system of claim 1, wherein: when the total number of the motors is odd, the motors are distributed into a first group of motors and a second group of motors, and the number of the motors is different from one another.

4. The multi-axis motor control system of claim 1, wherein: the control command is used for controlling the motor to perform required corresponding actions.

5. The multi-axis motor control system of claim 1, wherein: the pulse width modulation carrier module comprises a pulse width modulation carrier generation component, a control component and a pulse width modulation command updating circuit; the control component is responsible for controlling phase difference setting, pulse width modulation period setting and pulse width modulation command updating time setting between two groups of carriers, the pulse width modulation carrier generation component generates a first group of carrier signals and a second group of carrier signals according to the phase difference setting and the received pulse width modulation period setting provided by the control component, and the pulse width modulation command updating circuit updates the synchronous pulse width modulation command according to the pulse width modulation command updating time setting received by the control component.

6. A multi-shaft motor control method is applied to drive and control of a plurality of motors, the motors are divided into two groups, namely a first group of motors and a second group of motors, and the multi-shaft motor control method is characterized in that: the method comprises the following steps:

generating a control command, a pulse width modulation period setting and a pulse width modulation command updating time setting for a multi-shaft motor driver, wherein the multi-shaft motor driver internally comprises a control module, a pulse width modulation carrier module, a first group of comparators, a second group of comparators, a first group of pulse width modulation inverters and a second group of pulse width modulation inverters;

the control module receives the control command and then generates a first group of voltage commands and a second group of voltage commands; the pulse width modulation carrier module generates a first group of carrier signals and a second group of carrier signals after receiving the pulse width modulation period setting and the pulse width modulation command updating time setting, the phase difference between the first group of carrier signals and the second group of carrier signals is 180 degrees, and the pulse width modulation command updating time of the first group of carrier signals and the pulse width modulation command updating time of the second group of carrier signals are synchronized according to the pulse width modulation command updating time setting;

generating a first set of modulation voltages after receiving the first set of voltage commands and the first set of carrier signals through the first set of comparators, and generating a second set of modulation voltages after receiving the second set of voltage commands and the second set of carrier signals through the second set of comparators;

and the first group of pulse width modulation inverters and the second group of pulse width modulation inverters respectively receive the first group of modulation voltage and the second group of modulation voltage, then respectively generate alternating current voltage and respectively drive the first group of motors and the second group of motors.

7. The multi-axis motor control method according to claim 6, wherein: when the total number of the motors is even, the motors are evenly distributed into a first group of motors and a second group of motors which are equal in number.

8. The multi-axis motor control method according to claim 6, wherein: when the total number of the motors is odd, the motors are distributed into a first group of motors and a second group of motors which are different in number by one.

9. The multi-axis motor control method according to claim 6, wherein: the control command is used for controlling the motor to perform required corresponding actions.

10. The multi-axis motor control method according to claim 6, wherein: the pulse width modulation carrier module comprises a pulse width modulation carrier generation component, a control component and a pulse width modulation command updating circuit; the control component is responsible for controlling phase difference setting, pulse width modulation period setting and pulse width modulation command updating time setting between two groups of carriers, the pulse width modulation carrier generation component generates the first group of carrier signals and the second group of carrier signals according to the phase difference setting provided by the control component and the received pulse width modulation period setting, and the pulse width modulation command updating circuit updates the synchronous pulse width modulation command according to the pulse width modulation command updating time setting received from the control component.

Images