TWI781548B - Apparatus of motor control and its dc-link voltage control method - Google Patents

Abstract

An apparatus of motor control and its dc-link voltage control method which are used for driving motor and dc-link voltage optimization control, include power supply, motor drives and motor. The motor drives includes a command receiving device, converter, inverter, controller, current detection circuit and voltage detection circuit. The motor drives receives position, speed, or/and current command by command receiving device and receives the feedback signal of the dc-link voltage detected by the voltage detection circuit and the current feedback of the motor detected by the current detection circuit then controls the motor with the pulse width modulation signal calculated by the controller. Under the steady state operation of the motor, the controller calculate and process the signal according to the performance index, including modulation index, torque ripple, torque current ripple, speed ripple, low-order current harmonic components or total harmonic distortion to keep the above-mentioned index within the required hysteresis band, or the tuning method of dc-link voltage optimization. Furthermore, the related optimal dc-link voltage control command is generated by the optimal dc-link voltage optimal method. The converter will adjust the dc-link voltage of inverter based upon this optimal dc-link voltage command to achieve the optimal dc-link voltage control of motor drives system.

Description

Motor control device and DC link voltage control method thereof

The invention relates to a motor control device and its DC link voltage control method, which refers to a high-performance motor control technology applied to drive a motor and optimize its DC link voltage.

The basic motor control system diagram, as shown in Figure 1, includes a power supply 1, a motor 2 and a motor driver 3, and the motor driver 3 includes: an AC-DC conversion device 4, a frequency converter 5 and a controller 6, The control process is that the power provided by the motor driver 3 input power supply 1 is converted into a DC link voltage through the AC-DC conversion device 4, and the DC link voltage is input into the inverter 5, and the controller 6 utilizes voltage flux control (VF Control) , field-oriented control or direct torque control and other commonly known motor control technologies, the frequency converter 5 is controlled by pulse width modulation technology, so that it can output a power supply with adjustable voltage and adjustable frequency to achieve the purpose of controlling the motor 2 , this control technology has the advantage of adjustable speed operation, and is widely used in industrial equipment or household motors to save energy or to improve automation performance, and can also be used in industrial applications such as robots and electric vehicle drive systems.

Like the motor control system mentioned above, the DC link voltage required by the inverter 5 is converted from the AC power of the mains through the AC-DC conversion device of the previous stage. Therefore, it is usually only converted according to the power provided by different regions or regulations. Given a fixed DC link voltage to the frequency converter 5, it can be seen that its DC link voltage does not have variability, and the harmonics generated when pulse width modulation technology is used The composition is in the lower speed range of motor 2. Because the DC link voltage is too high relative to the back EMF voltage of motor 2, the amplitude modulation index is too low, and its relative harmonic content is relatively high. If motor 2 operates in the same speed range It can be found that the current waveform has higher harmonic components under the condition of higher DC link voltage. It can be seen that if the DC link voltage is fixed, it is easy to produce higher harmonic components under the operation of relatively low back EMF of the motor. Harmonics will affect the high-performance operation of the motor control system, and even endanger the surrounding equipment. Therefore, it is a technical point to control the harmonics in an appropriate range to prevent various problems.

The technology disclosed in the Republic of China Patent Publication No. 202010241 is a motor controller. Through a control circuit and a voltage adjustment circuit, a control signal is output according to the control circuit, so that the voltage adjustment circuit receives the signal and adjusts its The voltage level of the output voltage can be lower or higher than the input power supply. Its advantage is that it can increase the output voltage level to overcome the back electromotive force of the motor; or it can reduce the output voltage level and adjust the charging current to make it Recharge the battery at the proper voltage level. However, its method does not fully disclose the way its voltage command is determined, and its method does not solve harmonics such as torque ripple, torque current ripple, speed ripple, current low-order harmonic components, or its total harmonic distortion. wave control topic.

Furthermore, the technology disclosed in the Republic of China Patent Publication No. 201631880 also provides a motor module that adjusts the DC voltage through its motor controller. The method is mainly to solve the problem of motor noise. The method is to find out the temperature in advance The relationship with the rotation speed determines the hot spot temperature and the corresponding specific rotation speed. At the same time, according to the relationship between the rotation speed and voltage, the specific voltage at a specific rotation speed is determined. After using the above information to build a table, the DC voltage is adjusted according to the actual rotation speed. The method must be built manually, and at the same time, it cannot solve the harmonic control issues such as torque ripple, torque current ripple, speed ripple, low-order current harmonic component or its total harmonic distortion.

The present invention was developed to solve the above problems, and its purpose is to provide a motor control device and its DC link voltage control method. The developed harmonic optimization control method enables the DC link voltage received by the inverter to operate according to the motor. The situation is related to harmonics and automatically adjusts to the best voltage value, because the speed of the motor is linearly related to the back electromotive force, and the advantage of voltage adjustment can solve the problem that the motor operates in the linear region of the modulation index, due to low speed Generate low back electromotive force, so that the modulation index is too low and the harmonics are too high, adjust the DC link voltage to increase the modulation index until the modulation index reaches the hysteresis range of the upper limit of the linear region; or adjust the DC Link voltage, reduce the judgment amount including torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion, until the judgment amount reaches the hysteresis range of its minimum value.

Therefore, the advantages of the DC link voltage control method of the present invention will be able to solve the harmonic components of the motor under different operating conditions, wherein the required judgment quantities for establishing the modulation law of the DC link voltage value include: modulation index, torque Ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion and other values, using this method to control the motor harmonics within the optimal range.

The motor control device of the present invention includes: a power supply 7, a motor 8 and a motor driver 9, wherein the power supply 7 can be an AC power supply or a DC power supply, and the motor driver 9 includes: a command receiving device 10, a Voltage converter 11, a frequency converter 12, a controller 13, a voltage detection circuit 14 and a current detection circuit 15 are the position/speed/current command received by the command receiving device 10 of the motor driver 9, and the current detection circuit 15 The received motor 8 feedback signal is used to control the position/speed/current of the motor, and the DC link voltage command obtained by the DC link voltage control method of the present invention is used with the voltage detection circuit 14 to detect the feedback signal of the DC link voltage. Then, the voltage control is achieved by using the known voltage control technology.

In the motor control device and its DC link voltage control method of the first invention, the motor driver 9 receives the feedback signal of the DC link voltage detected by the voltage detection circuit 14 of the voltage converter 11 in the steady state of motor operation, and passes the The controller 13 calculates the value of the modulation index of the pulse width modulation, and the controller 13 uses the modulation index as a judgment value to adjust the DC link voltage to increase the modulation index until the modulation index reaches the upper limit of the linear region In the hysteresis interval of the value; first, judge whether the quantity exceeds the maximum linear modulation index based on this, if it exceeds the linear modulation area index, multiply the previous DC link voltage command by a real number greater than 1, so that the modulation index is in the linear area Then, according to the adjustment rule and the hysteresis interval (Min_hys~Max_hys) of the initial setting, it is judged to determine the value of the DC link voltage command that needs to be adjusted, so as to generate the corresponding voltage adjustment command, and the hysteresis interval of the initial setting modulation index Between 0.6~0.8, but not limited to the scope and quantity of the initial setting, the actual situation should be used as the reference for the main setting, therefore, the voltage converter 11 will adjust the value given to the inverter 12 according to the value of the voltage adjustment command DC link voltage to achieve optimal DC link voltage control for motor control systems.

The motor control device and its DC link voltage control method of the second invention is that the motor driver 9 receives the feedback signal of the DC link voltage detected by the voltage detection circuit 14 of the voltage converter 11 and the current detection circuit in the steady state of the motor. The feedback signal of the motor current detected by 15, the controller 13 uses torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion as the judgment quantity, and is used for Calculate the slope or change value between the judgment quantity of the previous calculation period, and then compare the judgment quantity with the judgment quantity of the previous calculation period and the judgment quantity of the previous two calculation periods according to the adjustment rule. If The result is the case where the judgment amount of the previous calculation cycle is the lowest, indicating that the best DC link voltage that can obtain the lowest judgment amount has been tracked, and this is the value of the voltage adjustment command of the voltage converter 11; the judgment result When the optimal DC link voltage is not reached, the obtained slope or change value is used to determine the voltage adjustment command. When the slope or change value is positive, the DC link voltage command is reduced, and vice versa, it is increased, so as to obtain the best voltage adjustment command. The voltage converter 11 adjusts the DC link voltage input to the inverter 12 according to the value of the voltage adjustment command, so as to achieve the optimal DC link voltage control of the motor control system.

1: Power

2: motor

3: Motor driver

4: AC-DC conversion device

5: Inverter

6: Controller

7: Power

8: Motor

9: Motor driver

10: Command receiving device

11:Voltage Converter

12: Inverter

13: Controller

14: Voltage detection circuit

15: Current detection circuit

16: Position signal detection circuit

S100: start

S101: The motor driver receives the output voltage feedback signal of the voltage converter

S102: the controller calculates the modulation index as the judgment quantity

S103: Judgment amount > maximum linear modulation index

S104: multiply the previous DC link voltage command by a real number greater than 1

S105: Judgment amount <= hysteresis interval lower limit Hys_Min

S106: Decrease DC link voltage command

S107: Judgment amount>=hysteresis interval upper limit Hys_Max

S108: Increase DC link voltage command

S109: Set the command of the voltage converter

S110: Adjust DC link voltage

S111: return

S200: start

S201: The motor driver receives the current feedback signal and the output voltage feedback signal of the voltage converter

S202: The controller calculates torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion, etc., as the judgment quantity

S203: The slope or change value between the judgment quantity calculated by the controller and the judgment quantity of the previous calculation cycle

S204: The judgment amount of the previous calculation cycle < the judgment amount of the previous two calculation cycles && the judgment amount of the previous calculation cycle < the judgment amount

S205: Slope or change value>0

S206: Decrease DC link voltage command

S207: Increase DC link voltage command

S208: set the voltage converter command

S209: Adjust DC link voltage

S210: return

Figure 1 is a basic motor control system diagram;

2 is a block diagram of a motor control device and a DC link voltage control method thereof of the present invention;

Fig. 3 is the implementation flowchart of the first invention of the present invention; and

Fig. 4 is the implementation flowchart of the second invention of the present invention.

In order to enable your examiners to have a further understanding of the characteristics and implementation of the present invention, I would like to illustrate in detail the implementation of the motor control device and its DC link voltage control method of the present invention with illustrations, as follows:

FIG. 2 is a block diagram of an embodiment of the motor control device and its DC link voltage control method of the present invention. The motor control device of the present invention includes: a power supply 7 , a motor 8 and a motor driver 9 . Wherein the power supply 7 can be an AC power supply or a DC power supply, and the motor driver 9 includes: a command receiving device 10, a voltage converter 11, a frequency converter 12, a controller 13, a voltage detection circuit 14 and a current detection circuit 15. Wherein the motor driver 9 receives the command of position/speed/current by the command receiving device 10, and the signal of the motor current is detected by the current detection circuit 15. Number, and then achieve position/speed/current control by conventional motor control technology, and the DC link voltage command obtained by the DC link voltage optimization control method, and the voltage detection circuit 14 to detect the return of the DC link voltage signal to achieve the best DC link voltage control.

Fig. 3 is the flow chart of the embodiment of the first invention of the motor control device and its DC link voltage control method of the present invention, the process is started by the motor driver 9 operating the motor 8 in a steady state (S100), the motor driver 9 Receive the feedback signal of the DC link voltage detected by the voltage detection circuit 14 of the voltage converter 11 (S101), and then calculate the value of the modulation index of the pulse width modulation obtained by the controller 13, according to this The modulation index is the judgment quantity of the adjustment method (S102). Firstly, it is judged whether the quantity exceeds the maximum linear modulation index (S103). If the result is yes, the previous DC link voltage command is multiplied by a real number greater than 1 (S104). Make the modulation index in the linear region; if the result is negative, enter the judgment of the adjustment step (S105), the initial hysteresis interval (Hys_Min~Hys_Max) is used as the upper and lower limits of the judgment, when the judgment amount is less than or equal to the lower limit of the hysteresis interval ( Hys_Min) (S105), then reduce the DC link voltage command (S106); if the judgment value is greater than or equal to the upper limit of the hysteresis interval (Hys_Max) (S107), then increase the DC link voltage command (S108). After the aforementioned judgment, the command to increase or decrease the DC link voltage is obtained to generate a corresponding voltage adjustment command to set the command of the voltage converter 11 (S109). The initial set modulation index is between 0.6~0.8, but not limited thereto. The scope and quantity of the initial setting should use the actual situation as the reference for the main setting. Therefore, the voltage converter 11 will adjust the DC link voltage given to the frequency converter 12 according to the value of the voltage adjustment command (S110), and finally return to the next calculation cycle process (S111), through the process of the above embodiment, to achieve Optimal DC link voltage control for motor control systems.

Fig. 4 is a flow chart of the embodiment of the second invention of the motor control device and its DC link voltage control method of the present invention, the process is to use the motor driver 9 to operate the motor 8 in Start under steady state (S200), receive the DC link voltage feedback signal detected by the voltage detection circuit 14 of the voltage converter 11 and the motor current feedback signal detected by the current detection circuit 15 (S201), and then pass through the controller 13 After the calculation, a value including torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion is obtained as a judgment quantity (S202), and adjusted according to the judgment quantity value, But it is not limited to the scope and quantity of this judgment quantity, it should conform to the actual use as the reference of the main setting, and it is used to calculate the slope value or change value (S203) between the judgment quantity of the previous calculation cycle, using the previous calculation The judgment amount of the cycle and the judgment amount of the previous two calculation cycles are used as comparison values to determine whether the judgment amount of the previous calculation cycle is smaller than the judgment amount of the previous two calculation cycles, and whether the judgment amount of the previous calculation cycle is smaller than the judgment amount (S204 ). If the judgment is yes, it will be displayed as the best judgment value, and then set as the best DC link voltage command, that is, stop adjusting and return to the next calculation cycle (S210); if the judgment result is no, judge the slope Or whether the change value is greater than the value zero (S205), if it is judged yes, decrease the DC link voltage command (S206); otherwise, increase the DC link voltage command (S207). After the aforementioned determination, the increase or decrease of the DC link voltage command is obtained to generate a corresponding voltage adjustment command for setting the value of the voltage adjustment command of the voltage converter 11 (S208), so as to adjust the DC link voltage input to the inverter 12 (S209), Then return to the process (S210), and continue the implementation process of the next calculation cycle. From the above process, the optimal DC link voltage traced to the lowest judgment value can be obtained to achieve the optimal DC link voltage control of the motor control system.

According to the motor control device and its DC link voltage control method of the present invention, the controller 13 calculates the torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion. relationship, and as the basis for the implementation of the voltage adjustment method, and through the voltage converter 11 to achieve the advantages of the adjustable DC link voltage of the motor drive system, the motor driver 9 controls the motor 8 to operate in the linear region of the modulation index, Low back EMF due to low speed, When the modulation index is too low and the harmonics are too high, it can be automatically adjusted according to the appropriate DC link voltage, so that the modulation index in the linear region is relatively low and the modulation index is increased and maintained in the linear region. In this case, its relative harmonic content is therefore reduced to reduce the harmonics of the motor control system, and can track the optimal DC link voltage with the lowest harmonic influence, solving the situation where the motor drive system operates at a fixed DC link voltage Harmonic problems under the environment, and make the motor control system achieve the best effect of DC link voltage control.

The above detailed description is a specific description of a feasible embodiment of the present invention, but this embodiment is not used to limit the patent scope of the present invention, and any equivalent implementation or change that does not depart from the technical spirit of the present invention shall be included in Within the scope of the patent application of the present invention.

7: Power

8: Motor

9: Motor driver

10: Command receiving device

11:Voltage Converter

12: Inverter

13: Controller

14: Voltage detection circuit

15: Current detection circuit

16: Position signal detection circuit

Claims (9)

A motor control device, used to drive a motor and optimize its DC link voltage, the device includes: a power supply, as the input power supply of the motor control system, which can be an AC power supply or a DC power supply; a motor, used as an input power supply in the motor control system The motor can generate the current signal of the motor; a motor driver, coupled with the power supply and the motor, accepts the power input, converts it into a variable DC link voltage through a voltage converter, and outputs it to a frequency converter, and then uses the frequency converter to The pulse width modulation technology is used to achieve the pulse output of the three-phase AC voltage to drive the motor to run; its features include a motor control circuit and a DC link voltage control circuit. The motor control device as described in claim 1, which includes a controller as the calculation and signal processing of the motor driver, connected with a command receiving device, a voltage detection circuit and a current detection circuit, and can process the command receiving device The position/speed/current command received, the DC link voltage feedback signal received by the voltage detection circuit, the current feedback signal received by the current detection circuit, and the pulse wave reaching the position/speed/current control technology The width modulation signal is output to the inverter for position/speed/current control, and the pulse width modulation signal for DC link voltage control is output to a voltage converter for DC link voltage control. The motor control device as described in Claim 1, which includes a voltage converter connected to the frequency converter, which can accept AC power or DC power, and according to the pulse width modulation signal generated by the DC link voltage control loop, According to its modulating signal, it can output variable DC link voltage; in addition, any voltage converter that conforms to the characteristic of variable DC link voltage is its characteristic. A DC link voltage control method, which is calculated by the controller under the operation of the motor, including modulation index, torque ripple, torque current ripple, speed ripple, and current low-order harmonic components. It can automatically calculate the best DC link voltage command, and then set it to the DC link voltage control circuit, so that it can output pulse width modulation signal to control the voltage converter, so as to achieve The purpose of voltage adjustment; the calculation of the optimal DC link voltage command is to include modulation index, torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion in Within the allowable hysteresis interval, it is also possible to judge whether the calculation result is the lowest, to determine the optimal DC link voltage command, and to adjust the voltage according to the positive and negative changes of the slope or the change value if it is not optimal. , and finally to achieve the best DC link voltage command. The DC link voltage control method as described in Claim 4, wherein the modulation index calculated by the controller is used as the judgment quantity required for the judgment, and its characteristics include the characteristics of the linear modulation region and the over-modulation region, This is used as a basis for judging that it is necessary to multiply the previous DC link voltage command by a real number greater than 1 to increase the voltage in the over-modulation region or to perform optimal DC link voltage command control in the linear region. The DC link voltage control method as described in Claim 4, wherein the torque ripple, torque current ripple, speed ripple, current low-order harmonic component or its total harmonic distortion calculated by the controller is used , at least one item is used as the judgment quantity required for the judgment, and the calculation algorithm and formula conditions for calculating the judgment quantity include methods that can achieve the purpose. The DC link voltage control method as described in Claim 4, wherein the initial setting of the upper and lower limits of the hysteresis interval, but not limited to a fixed range and quantity, should conform to actual specifications and use conditions as the main reference for setting. The DC link voltage control method as described in claim 4, wherein the calculation of judging whether the result is the minimum is to record the value obtained in the previous two calculation cycles and compare it with the current value. The sorting and searching methods of the calculation characteristics to obtain the lowest quantity are its characteristics. The DC link voltage control method as described in Claim 4, wherein the basis for the modulation of the optimal DC link voltage command is based on the slope or change value, and is characterized by calculating the value obtained in the previous calculation cycle and the current value, and has the following characteristics: The characteristics of positive and negative changes. According to this characteristic, the DC link voltage command can reduce the voltage when it changes positively or increase the voltage when it changes negatively. In addition, all calculation methods and values that meet the characteristics of positive and negative changes are its characteristics.

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