A machine tool PWM rectifier energy-saving control method and system based on working condition self-adaptation

Abstract

The application discloses a kind of based on working condition self-adaptive machine tool PWM rectifier energy-saving control method and system, wherein the method comprises the following steps: numerical control system real-time acquisition machine tool operating condition and using operation mode judgment strategy to process and obtain operation mode instruction, operation mode instruction is input to the controller of PWM rectifier, and operation mode instruction includes static rectification mode and PWM rectification mode;The controller of PWM rectifier obtains operation mode instruction and controls PWM rectifier to enter corresponding working mode, when the controller of PWM rectifier obtains static rectification or PWM rectification mode instruction, the controller of PWM rectifier can close or open the high-frequency switching action of PWM rectifier internal power device, so that PWM rectifier only utilizes the diode characteristics of power device or switch and carries out static or normal rectification.The disclosed method can control PWM rectifier to work in different modes according to the operating condition of machine tool, and energy saving can be effectively realized.

Description

Technical Field

[0001] This invention relates to the field of machine tool control technology, and in particular to an energy-saving control method and system for machine tool PWM rectifiers based on adaptive operating conditions. Background Technology

[0002] Modern high-end CNC machine tools widely use PWM rectifiers as their front-end power supply to achieve advantages such as high power factor, low harmonic pollution, and energy feedback. However, this technology suffers from significant energy waste in practical applications: regardless of whether the machine tool is in machining, paused, or standby mode, the PWM rectifier always operates in a high-frequency switching "PWM rectification mode." During machining, the braking energy of the machine tool's axis motors can be fed back to the grid, resulting in significant energy savings. However, during prolonged standby or debugging periods, the lack of recoverable braking energy, coupled with iron losses in the front-end reactor and switching losses in the power devices, leads to higher no-load losses for the PWM rectifier compared to traditional static rectifier power supplies, resulting in unnecessary energy waste. Therefore, existing technologies struggle to balance efficient operation with standby energy saving, especially failing to achieve optimal energy efficiency during non-machining periods. Summary of the Invention

[0003] This invention addresses the problems existing in the prior art by proposing an energy-saving control method for machine tool PWM rectifiers based on operating condition adaptation.

[0004] The technical means employed in this invention are as follows: An energy-saving control method for machine tool PWM rectifiers based on operating condition adaptation includes the following steps: Step 1: The CNC system collects the machine tool's operating conditions in real time, processes the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions, and inputs the operating mode instructions to the controller of the PWM rectifier. The operating mode instructions include static rectification mode and PWM rectification mode. Step 2: The controller of the PWM rectifier obtains the operating mode instruction and controls the PWM rectifier to enter the corresponding working mode. When the controller of the PWM rectifier obtains the static rectification mode instruction, the controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. When the controller of the PWM rectifier receives the PWM rectification mode command, the controller of the PWM rectifier starts the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power device to perform PWM rectification.

[0005] Furthermore, the machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state; The operation mode determination strategy is as follows: when the machine tool is in standby mode, paused mode, alarm mode, emergency stop mode, measurement mode and power off mode, the operation mode command is static rectification mode; When the machine tool is in automatic machining mode and does not include any of the following states: standby mode, pause mode, alarm mode, emergency stop mode, measurement mode, or power off mode, the operating mode command is PWM rectification mode.

[0006] Furthermore, when the controller of the PWM rectifier receives a static rectification mode instruction, the controller of the PWM rectifier is also used to perform adaptive judgment processing to determine whether the current PWM rectifier is an executable operating mode switching instruction. If yes, the controller controls the PWM rectifier to execute the static rectification mode instruction; if no, the controller controls the PWM rectifier to maintain the current operating mode unchanged. The adaptive judgment process includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. If all three of the above judgments are switchable modes, the PWM rectifier is determined to be able to execute the working mode switching instruction; otherwise, the PWM rectifier is determined to be unable to execute the working mode switching instruction.

[0007] Furthermore, the controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system.

[0008] A system for implementing the machine tool PWM rectifier energy-saving control method based on operating condition adaptation as described in this invention includes: The numerical control system is used to collect the machine tool's operating conditions in real time, process the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions, and input the operating mode instructions to the controller of the PWM rectifier. The operating mode instructions include static rectification mode and PWM rectification mode. The controller of the PWM rectifier is used to obtain the operating mode command and control the PWM rectifier to enter the corresponding working mode. When the controller of the PWM rectifier obtains the static rectification mode command, the controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. When the controller of the PWM rectifier receives the PWM rectification mode command, the controller of the PWM rectifier starts the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power device to perform PWM rectification. A PWM rectifier is used to rectify the input power supply and supply power to the DC bus under the control of the controller of the PWM rectifier.

[0009] Furthermore, the machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state; The operation mode determination strategy is as follows: when the machine tool is in standby mode, paused mode, alarm mode, emergency stop mode, measurement mode and power off mode, the operation mode command is static rectification mode; When the machine tool is in automatic machining mode and does not include any of the following states: standby mode, pause mode, alarm mode, emergency stop mode, measurement mode, or power off mode, the operating mode command is PWM rectification mode.

[0010] Furthermore, when the controller of the PWM rectifier receives a static rectification mode instruction, the controller of the PWM rectifier is also used to perform adaptive judgment processing to determine whether the current PWM rectifier is an executable operating mode switching instruction. If yes, the controller controls the PWM rectifier to execute the static rectification mode instruction; if no, the controller controls the PWM rectifier to maintain the current operating mode unchanged. The adaptive judgment process includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. If all three of the above judgments are switchable modes, the PWM rectifier is determined to be able to execute the working mode switching instruction; otherwise, the PWM rectifier is determined to be unable to execute the working mode switching instruction.

[0011] Furthermore, the controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system.

[0012] Compared with existing technologies, the energy-saving control method for machine tool PWM rectifiers based on adaptive operating conditions disclosed in this invention has the following beneficial effects: In this application, since the CNC system can send different operating mode commands to the controller of the PWM rectifier according to the machine tool's operating conditions, it achieves the following: when a high-end CNC machine tool requires high-performance power supply, the PWM rectifier adopts "PWM rectification mode" to ensure stable DC bus voltage, fast dynamic response, and high power quality. Conversely, the PWM rectifier automatically switches to static rectification mode. In this mode, the high-frequency switching action of the power devices inside the PWM rectifier is turned off, and only the diode characteristics of the power devices themselves are used for "static rectification," thereby completely eliminating the losses of the power devices in the PWM rectifier during high-frequency switching action and the power consumption of the drive circuit and control chip, achieving deep energy saving. Attached Figure Description

[0013] Figure 1 This is a flowchart of the machine tool PWM rectifier energy-saving control method based on working condition adaptation disclosed in this invention; Figure 2 This is a flowchart of the energy-saving control method for machine tool PWM rectifiers based on adaptive operating conditions disclosed in this invention. Figure 3 This is a flowchart illustrating the determination of machine tool operating conditions in the machine tool PWM rectifier energy-saving control method based on operating condition adaptation disclosed in this invention. Detailed Implementation

[0014] like Figure 1 , Figure 2 and Figure 3 As shown, the energy-saving control method for machine tool PWM rectifiers based on adaptive operating conditions disclosed in this invention includes the following steps: Step 1: The CNC system collects the machine tool's operating conditions in real time, processes the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions, and inputs the operating mode instructions to the controller of the PWM rectifier. The operating mode instructions include static rectification mode and PWM rectification mode. Step 2: The controller of the PWM rectifier obtains the operating mode instruction and controls the PWM rectifier to enter the corresponding working mode. When the controller of the PWM rectifier obtains the static rectification mode instruction, the controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. When the controller of the PWM rectifier receives the PWM rectification mode command, the controller of the PWM rectifier starts the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power device to perform PWM rectification.

[0015] The present invention discloses an energy-saving control method for machine tool PWM rectifier based on working condition adaptation. The numerical control system (NC system) collects the machine tool operating conditions in real time and processes and analyzes the machine tool operating conditions based on the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions. The operating mode instructions include static rectification mode and PWM rectification mode. Then, the numerical control system inputs the obtained operating mode instructions to the controller of the PWM rectifier. When the controller of the PWM rectifier receives the static rectification mode command, the controller of the PWM rectifier can turn off the high-frequency switching action of the power devices inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power devices for static rectification. When the controller of the PWM rectifier receives a PWM rectification mode command, it can initiate the high-frequency switching action of the internal power devices of the PWM rectifier, enabling the PWM rectifier to utilize the switching characteristics of the power devices for PWM rectification. In other words, in this application, when a high-end CNC machine tool requires high-performance power supply, the PWM rectifier adopts "PWM rectification mode" to ensure stable DC bus voltage, fast dynamic response, and high power quality. Conversely, the PWM rectifier automatically switches to static rectification mode. In this mode, the high-frequency switching action of the internal power devices of the PWM rectifier is turned off, and only the diode characteristics of the power devices themselves are used for "static rectification," thereby completely eliminating the losses of the power devices during high-frequency switching and the power consumption of the drive circuit and control chip, achieving deep energy saving. Simultaneously, the system can remain ready in static rectification mode, and once it detects that the machine tool requires high-performance power supply, it can seamlessly switch back to "normal working mode" without delaying production. The energy-saving control method for machine tool PWM rectifiers disclosed in this invention has significant energy-saving effects, no loss of user experience, high safety and reliability, low implementation cost, and is easy to promote; it is in line with the trend of intelligent manufacturing.

[0016] Furthermore, the machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state; The operation mode determination strategy is as follows: when the machine tool is in standby mode, paused mode, alarm mode, emergency stop mode, measurement mode and power off mode, the operation mode command is static rectification mode; When the machine tool is in automatic machining mode and does not include any of the following states: standby mode, pause mode, alarm mode, emergency stop mode, measurement mode, or power off mode, the operating mode command is PWM rectification mode.

[0017] Specifically, in this embodiment, the machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state. When the machine tool is in standby, pause, alarm, emergency stop, measurement, or shutdown state, it indicates that the machine tool does not require the supply of "high-performance power". Therefore, the PWM rectifier can enter the static rectification mode. At this time, the CNC system determines that the current operating mode instruction is the static rectification mode. The controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. In this embodiment, the above machine tool operating conditions are as follows: (1) Standby: no emergency stop, normal power-on, no alarm, and the program does not run automatically; (2) Pause: the program is automatically paused, and the pause status signal is valid; (3) Alarm: the machine tool has a fault, and the alarm status signal is valid; (4) Emergency stop: manual emergency stop, and the emergency stop status signal is valid; (5) Measurement: jogging operation, and the test status signal is valid; (6) Shutdown: the NC system is not powered on, and the shutdown status signal is valid. When the machine tool is operating in automatic machining mode and does not include any of the following states: standby, pause, alarm, emergency stop, measurement, or shutdown, the machine tool is in normal machining program mode, and the operating mode command is PWM rectification mode. At this time, the CNC system determines that the current operating mode command is PWM rectification mode, and the controller of the PWM rectifier activates the high-frequency switching action of the power devices inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power devices to perform PWM rectification. This ensures stable DC bus voltage, fast dynamic response, and high power quality.

[0018] Furthermore, when the controller of the PWM rectifier receives a static rectification mode instruction, the controller of the PWM rectifier is also used to perform adaptive judgment processing to determine whether the current PWM rectifier is an executable operating mode switching instruction. If yes, the controller controls the PWM rectifier to execute the static rectification mode instruction; if no, the controller controls the PWM rectifier to maintain the current operating mode unchanged. The adaptive judgment process includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. If all three of the above judgments are switchable modes, the PWM rectifier is determined to be able to execute the working mode switching instruction; otherwise, the PWM rectifier is determined to be unable to execute the working mode switching instruction.

[0019] Specifically, when the controller of the PWM rectifier receives a static rectification mode command, the controller of the PWM rectifier is also used to perform adaptive judgment processing, which includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The real-time load factor (%) of a PWM rectifier is defined as the ratio of the current DC bus output power to its rated output power. That is: Load factor = (Vdc × Idc) / Pn × 100%; Where Vdc is the measured DC bus voltage, Idc is the measured DC bus current, and Pn is the rated power of the PWM rectifier.

[0020] The first load rate threshold and the first time threshold can be set according to actual needs. In this embodiment, the first load rate threshold is set to 10%, and the first time threshold is set to 5000ms. The aforementioned Vdc and Idc need to be the average value obtained after multiple control cycles to calculate the current stable power value, avoiding misjudgments triggered by noise and instantaneous glitches. It also prevents frequent switching of the PWM rectifier.

[0021] The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. In other words, when the PWM rectifier triggers an alarm, the alarm status is responded to first, and the operating mode is not switched.

[0022] The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. The controller of the PWM rectifier monitors the quality of the power grid in real time. When the grid voltage fluctuation exceeds a set first voltage fluctuation threshold or the duration is less than a set second time threshold, the PWM rectifier does not perform a working mode switch. In this embodiment, the first voltage fluctuation threshold is set to 10%, and the second time threshold is set to 5000ms; that is, the controller of the PWM rectifier monitors the quality of the power grid in real time, and when the grid voltage fluctuation exceeds 10% or the duration is less than 5000ms, the PWM rectifier does not perform a working mode switch.

[0023] Once all three conditions are met, the PWM rectifier switches its operating mode. Conversely, if any condition is not met, the PWM rectifier does not switch its operating mode. This judgment logic avoids unnecessary switching during power grid fluctuations or load transients. It also ensures the reliability and stability of the PWM rectifier's operating mode switching.

[0024] Furthermore, the controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system.

[0025] Specifically, the controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system, so as to facilitate the judgment logic of other functions of the machine tool, and at the same time, to facilitate the CNC system to verify whether the PWM rectifier has completed the execution of the operating mode command given by the CNC system.

[0026] A system for implementing the machine tool PWM rectifier energy-saving control method based on operating condition adaptation as described in this invention includes: The numerical control system is used to collect the machine tool's operating conditions in real time, process the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions, and input the operating mode instructions to the controller of the PWM rectifier. The operating mode instructions include static rectification mode and PWM rectification mode. The controller of the PWM rectifier is used to obtain the operating mode command and control the PWM rectifier to enter the corresponding working mode. When the controller of the PWM rectifier obtains the static rectification mode command, the controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. When the controller of the PWM rectifier receives the PWM rectification mode command, the controller of the PWM rectifier starts the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power device to perform PWM rectification. A PWM rectifier is used to rectify the input power supply and supply power to the DC bus under the control of the controller of the PWM rectifier.

[0027] Specifically, the machine tool PWM rectifier energy-saving control system based on adaptive operating conditions disclosed in this invention involves the CNC system acquiring real-time machine tool operating conditions and processing and analyzing these conditions using an operating mode judgment strategy to obtain operating mode commands. These commands include static rectification mode and PWM rectification mode. The CNC system then inputs these commands to the PWM rectifier controller. When the PWM rectifier controller receives the static rectification mode command, it disables the high-frequency switching of the internal power devices, allowing the PWM rectifier to utilize only the diode characteristics of the power devices for static rectification. When the PWM rectifier controller receives the PWM rectification mode command, it activates the high-frequency switching of the internal power devices, enabling the PWM rectifier to utilize the switching characteristics of the power devices for PWM rectification. In other words, in this application, when a high-end CNC machine tool requires high-performance power supply, the PWM rectifier uses "PWM rectification mode" to ensure stable DC bus voltage, fast dynamic response, and high power quality. Conversely, the PWM rectifier automatically switches to static rectification mode. In this mode, the high-frequency switching of the power devices inside the PWM rectifier is turned off, and only the diode characteristics of the power devices themselves are used for "static rectification." This completely eliminates the losses of the power devices during high-frequency switching and the power consumption of the drive circuit and control chip, achieving deep energy saving. Simultaneously, the system remains ready in static rectification mode, and can seamlessly switch back to "normal working mode" once it detects that the machine tool requires a high-performance power supply, without disrupting production. The energy-saving control method for machine tool PWM rectifiers disclosed in this invention has significant energy-saving effects, no loss of user experience, high safety and reliability, low implementation cost, and is easy to promote; it aligns with the trend of intelligent manufacturing.

[0028] Furthermore, the machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state; The operation mode determination strategy is as follows: when the machine tool is in standby mode, paused mode, alarm mode, emergency stop mode, measurement mode and power off mode, the operation mode command is static rectification mode; When the machine tool is in automatic machining mode and does not include any of the following states: standby mode, pause mode, alarm mode, emergency stop mode, measurement mode, or power off mode, the operating mode command is PWM rectification mode.

[0029] Specifically, in this embodiment, the machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power-off state, and automatic machining state. When the CNC system detects that the machine tool is in at least one of the following states: standby state, pause state, alarm state, emergency stop state, measurement state, or power-off state, it indicates that the machine tool does not require the supply of "high-performance power". Therefore, the PWM rectifier can enter static rectification mode. At this time, the CNC system determines that the current operating mode command is static rectification mode, and the controller of the PWM rectifier shuts down the internal circuitry of the PWM rectifier. The high-frequency switching action of the power devices makes the PWM rectifier only use the diode characteristics of the power devices for static rectification; In this embodiment, the above machine tool operating conditions are as follows: (1) Standby: no emergency stop, normal power-on, no alarm, program does not run automatically; (2) Pause: program pauses automatically, pause status signal is valid; (3) Alarm: machine tool has a fault, alarm status signal is valid; (4) Emergency stop: manual emergency stop, emergency stop status signal is valid; (5) Measurement: jog operation, test status signal is valid; (6) Power off: NC system is not powered on, power off status signal is valid; When the CNC system detects that the machine tool is in automatic machining mode and does not include any of the following states: standby, pause, alarm, emergency stop, measurement, or shutdown, the operating mode command is PWM rectification mode. At this time, the CNC system determines that the current operating mode command is PWM rectification mode, and the controller of the PWM rectifier activates the high-frequency switching action of the power devices inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power devices to perform PWM rectification. This ensures stable DC bus voltage, fast dynamic response, and high power quality.

[0030] Furthermore, when the controller of the PWM rectifier receives a static rectification mode instruction, the controller of the PWM rectifier is also used to perform adaptive judgment processing to determine whether the current PWM rectifier is an executable operating mode switching instruction. If yes, the controller controls the PWM rectifier to execute the static rectification mode instruction; if no, the controller controls the PWM rectifier to maintain the current operating mode unchanged. The adaptive judgment process includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. If all three of the above judgments are switchable modes, the PWM rectifier is determined to be able to execute the working mode switching instruction; otherwise, the PWM rectifier is determined to be unable to execute the working mode switching instruction.

[0031] Specifically, when the controller of the PWM rectifier receives a static rectification mode command, the controller of the PWM rectifier is also used to perform adaptive judgment processing, which includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The real-time load factor (%) of a PWM rectifier is defined as the ratio of the current DC bus output power to its rated output power. That is: Load factor = (Vdc × Idc) / Pn × 100%; Where Vdc is the measured DC bus voltage, Idc is the measured DC bus current, and Pn is the rated power of the PWM rectifier.

[0032] The first load rate threshold and the first time threshold can be set according to actual needs. In this embodiment, the first load rate threshold is set to 10%, and the first time threshold is set to 5000ms. The aforementioned Vdc and Idc need to be the average value obtained after multiple control cycles to calculate the current stable power value, avoiding misjudgments triggered by noise and instantaneous glitches. It also prevents frequent switching of the PWM rectifier.

[0033] The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. In other words, when the PWM rectifier triggers an alarm, the alarm status is responded to first, and the operating mode is not switched.

[0034] The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. The controller of the PWM rectifier monitors the quality of the power grid in real time. When the grid voltage fluctuation exceeds a set first voltage fluctuation threshold or the duration is less than a set second time threshold, the PWM rectifier does not perform a working mode switch. In this embodiment, the first voltage fluctuation threshold is set to 10%, and the second time threshold is set to 5000ms; that is, the controller of the PWM rectifier monitors the quality of the power grid in real time, and when the grid voltage fluctuation exceeds 10% or the duration is less than 5000ms, the PWM rectifier does not perform a working mode switch.

[0035] Once all three conditions are met, the PWM rectifier switches its operating mode. Conversely, if any condition is not met, the PWM rectifier does not switch its operating mode. This judgment logic avoids unnecessary switching during power grid fluctuations or load transients. It also ensures the reliability and stability of the PWM rectifier's operating mode switching.

[0036] Furthermore, the controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system.

[0037] Specifically, the controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system, so as to facilitate the judgment logic of other functions of the machine tool, and at the same time, to facilitate the CNC system to verify whether the PWM rectifier has completed the execution of the operating mode command given by the CNC system.

[0038] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A machine tool PWM rectifier energy-saving control method based on operating condition adaptation, characterized in that, Includes the following steps: Step 1: The CNC system collects the machine tool's operating conditions in real time, processes the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions, and inputs the operating mode instructions to the controller of the PWM rectifier. The operating mode instructions include static rectification mode and PWM rectification mode. Step 2: The controller of the PWM rectifier obtains the operating mode instruction and controls the PWM rectifier to enter the corresponding working mode. When the controller of the PWM rectifier obtains the static rectification mode instruction, the controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. When the controller of the PWM rectifier receives the PWM rectification mode command, the controller of the PWM rectifier starts the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power device to perform PWM rectification.

2. The energy-saving control method for machine tool PWM rectifier based on adaptive operating conditions according to claim 1, characterized in that: The machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state; The operation mode determination strategy is as follows: when the machine tool is in standby mode, paused mode, alarm mode, emergency stop mode, measurement mode and power off mode, the operation mode command is static rectification mode; When the machine tool is in automatic machining mode and does not include any of the following states: standby mode, pause mode, alarm mode, emergency stop mode, measurement mode, or power off mode, the operating mode command is PWM rectification mode.

3. The energy-saving control method for machine tool PWM rectifier based on adaptive operating conditions according to claim 2, characterized in that: When the controller of the PWM rectifier receives a static rectification mode instruction, the controller of the PWM rectifier is also used to perform adaptive judgment processing to determine whether the current PWM rectifier is an executable operating mode switching instruction. If yes, the controller controls the PWM rectifier to execute the static rectification mode instruction; if no, the controller controls the PWM rectifier to maintain the current operating mode unchanged. The adaptive judgment process includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. If all three of the above judgments are switchable modes, the PWM rectifier is determined to be able to execute the working mode switching instruction; otherwise, the PWM rectifier is determined to be unable to execute the working mode switching instruction.

4. The energy-saving control method for machine tool PWM rectifier based on adaptive operating conditions according to claim 3, characterized in that: The controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system.

5. A system for implementing the machine tool PWM rectifier energy-saving control method based on working condition adaptation as described in any one of claims 1 to 4, characterized in that, include: The numerical control system is used to collect the machine tool's operating conditions in real time, process the collected machine tool operating conditions using an operating mode judgment strategy to obtain operating mode instructions, and input the operating mode instructions to the controller of the PWM rectifier. The operating mode instructions include static rectification mode and PWM rectification mode. The controller of the PWM rectifier is used to obtain the operating mode command and control the PWM rectifier to enter the corresponding working mode. When the controller of the PWM rectifier obtains the static rectification mode command, the controller of the PWM rectifier turns off the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier only uses the diode characteristics of the power device for static rectification. When the controller of the PWM rectifier receives the PWM rectification mode command, the controller of the PWM rectifier starts the high-frequency switching action of the power device inside the PWM rectifier, so that the PWM rectifier uses the switching characteristics of the power device to perform PWM rectification. A PWM rectifier is used to rectify the input power supply and supply power to the DC bus under the control of the controller of the PWM rectifier.

6. The system according to claim 5, characterized in that: The machine tool operating conditions include standby state, pause state, alarm state, emergency stop state, measurement state, power off state, and automatic machining state; The operation mode determination strategy is as follows: when the machine tool is in standby mode, paused mode, alarm mode, emergency stop mode, measurement mode and power off mode, the operation mode command is static rectification mode; When the machine tool is in automatic machining mode and does not include any of the following states: standby mode, pause mode, alarm mode, emergency stop mode, measurement mode, or power off mode, the operating mode command is PWM rectification mode.

7. The system according to claim 6, characterized in that: When the controller of the PWM rectifier receives a static rectification mode instruction, the controller of the PWM rectifier is also used to perform adaptive judgment processing to determine whether the current PWM rectifier is an executable operating mode switching instruction. If yes, the controller controls the PWM rectifier to execute the static rectification mode instruction; if no, the controller controls the PWM rectifier to maintain the current operating mode unchanged. The adaptive judgment process includes: The controller of the PWM rectifier obtains the load rate of the rectifier in real time, and determines whether the current load rate is less than a set first load rate threshold and whether the duration is greater than a set first time threshold. If so, it is determined to be a switchable mode; otherwise, it is determined to be a non-switchable mode. The controller of the PWM rectifier determines whether the current PWM rectifier is in an alarm state; if yes, it is determined to be in a non-switchable mode; if no, it is determined to be in a switchable mode. The controller of the PWM rectifier obtains the real-time grid voltage at the power supply terminal and determines whether the current grid voltage fluctuation is less than a set first voltage fluctuation threshold and the duration is greater than a set second time threshold based on the grid voltage at the power supply terminal. If yes, it is determined to be a switchable mode; if no, it is determined to be a non-switchable mode. If all three of the above judgments are switchable modes, the PWM rectifier is determined to be able to execute the working mode switching instruction; otherwise, the PWM rectifier is determined to be unable to execute the working mode switching instruction.

8. The system according to claim 7, characterized in that: The controller of the PWM rectifier is also used to feed back the current operating mode of the PWM rectifier to the CNC system.

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