A controller for a compressor

Abstract

The present invention discloses a controller for a compressor, which is based on sensorless FOC vector frequency conversion control and adopts sinusoidal current drive to minimize torque pulsation during motor operation; wherein, the controller adopts a segmented startup, including a rotor positioning stage, an open-loop control stage and a closed-loop control stage; when in the rotor positioning stage, the current value is gradually increased until the rotor is positioned and then enters the open-loop control stage; when in the open-loop control stage, the current value is gradually increased until the target current value is reached and then enters the closed-loop control stage; when in the closed-loop control stage, the speed closed-loop and current closed-loop drive motor are used to perform dual closed-loop operation; the present invention can minimize torque pulsation during motor operation, and at the same time, when the motor is started, the speed and current dual closed-loop control is adopted, which has a faster response speed to changes in motor load, makes the motor run more stable, and reduces noise.

Description

Technical Field

[0001] The present invention belongs to the field of compressor control, and in particular relates to a compressor controller. Background Art

[0002] In order to facilitate the compactness of the installation layout, people hope to adopt an integrated installation scheme for the controller of the vehicle-mounted electronic scroll compressor and the compressor body. Specifically, when implementing it, the controller is installed outside the compressor housing, and the compressor motor is sealed inside the compressor housing. This makes the compressor as a whole particularly sensitive to the noise of the motor during operation, and thus the compressor controller is

[0003] Therefore, based on the inventors' many years of dedicated R&D experience in the control field, they hope to seek new technical solutions to solve the above technical problems. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to propose a controller for a compressor, which particularly adopts sinusoidal current drive, which can minimize the torque pulsation during the operation of the motor. At the same time, when the motor starts, it adopts dual closed-loop control of speed and current, which has a faster response speed to changes in motor load, making the motor running speed more stable and reducing noise.

[0005] The technical solution adopted in the present invention is as follows:

[0006] A compressor controller is installed on the outside of the compressor housing, and a motor is installed on the inside of the compressor housing. The controller is used to drive the motor to operate, based on sensorless FOC vector frequency conversion control, and adopts sinusoidal current drive to minimize torque pulsation during motor operation; wherein, the controller adopts a segmented startup, including a rotor positioning stage, an open-loop control stage, and a closed-loop control stage. When in the rotor positioning stage, the current value is gradually increased until the rotor is positioned and then enters the open-loop control stage. When in the open-loop control stage, the current value is gradually increased until the target current value is reached and then enters the closed-loop control stage. When in the closed-loop control stage, the speed closed-loop and current closed-loop drive motors are used to perform dual closed-loop operation.

[0007] Preferably, the PWM carrier frequency of the controller is 16000 Hz.

[0008] Preferably, during the motor driving process, the controller is provided with a current constraint control, wherein the current constraint control includes: setting three current values 、 、 , and satisfies The relationship between the d-axis current , q-axis current Composite output current , and there are ; When detected The motor speed is not allowed to continue to increase; when it is detected When the speed is detected, the speed decreases at a predetermined deceleration rate; When the speed increases, it increases at a predetermined rate.

[0009] Preferably, during the motor driving process, the controller is provided with a field weakening control, wherein the field weakening control comprises: respectively controlling the d-axis voltage , q-axis voltage The value is filtered, when the output voltage Exceeding the field weakening limit voltage When the output voltage is With the field weakening limit voltage The difference is calculated by PI operation to obtain the target working current I d .

[0010] Preferably, during the startup process, when the actual motor speed is lower than 360 rpm, the low-speed D-axis current is allowed to Compensation, when the actual motor speed is higher than 480rpm, exit the low speed D axis current After successful startup, it is not allowed to enter the low-speed D-axis current again. compensate.

[0011] Preferably, when the low speed d-axis current When the compensation value is 0 and the torque compensation amplitude is 0, the output current The amplitude of the current is obtained by linear interpolation after looking up the table. After determining the β angle, calculate 、 .

[0012] Preferably, the d-axis current , q-axis current The calculation formula is:

[0013] .

[0014] Preferably, when the compressor is running, during the compression and suction process, the rotor load changes with the rotor position. At low speed, torque compensation is performed according to the rotor mechanical position to improve the load capacity of the compressor at low speed operation; the corresponding relationship between the mechanical angle and the electrical angle is confirmed by mechanical angle locking, and then the current low-speed D-axis current is calculated based on the rotor mechanical angle. The size of the compensation.

[0015] Preferably, each time the motor is started, the phase loss of the motor is detected, wherein, during the positioning phase of the starting process, when the current and angle are unchanged, the motor phase current is detected. , and perform low-pass filtering on the current;

[0016] ;

[0017] ;

[0018] ; ;

[0019] in, is the angle value at the end of the positioning phase, The choice of angle must ensure Both are not 0.

[0020] Preferably, in order to avoid phase loss, and When both are 0, no phase failure is detected. As a judgment value, when it is detected , When the deviation from the judgment value is not within the preset range, a phase loss fault reminder is set, and the motor drive is stopped after the fault occurs.

[0021] It should be noted that the compressor involved in this application is a scroll compressor.

[0022] The present invention adopts sensorless FOC vector frequency conversion (SVPWM) control technology to achieve optimal performance control. In view of the sensitivity of compressor motor applications to noise, this application specifically adopts sinusoidal current drive, which can minimize the torque pulsation during motor operation. At the same time, when the motor starts; it adopts speed and current dual closed-loop control to have a faster response speed to changes in motor load, making the motor running speed more stable and reducing noise; and preferably combines the introduction of current constraint control, weak magnetic control and phase loss detection to further facilitate the motor drive operation to be more stable and reliable and help reduce noise.

[0023] Since the compressor used in this application is a scroll compressor, one rotation of the compressor is equivalent to one mechanical cycle, which will cause the output torque of the motor to vary greatly, resulting in greater vibration when the motor is running at low speed. Therefore, during the low-speed operation of the motor, this application specifically adds a low-speed D-axis current. The compensation and torque compensation control functions are beneficial to the smooth operation of the motor during low-speed operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural diagram of a downsampling circuit in a specific embodiment of the present application;

[0025] Figure 2 This is a schematic diagram of the PWM, PDB, and ADC synchronous logic control process under a specific embodiment of the present application;

[0026] Figure 3 It is a schematic diagram of the relationship between the motor load torque fluctuation and the angle under the specific implementation mode of this application. DETAILED DESCRIPTION

[0027] An embodiment of the present invention discloses a controller for a compressor, which is installed on the outside of the compressor housing, and a motor is installed inside the compressor housing. The controller is used to drive the motor to operate, based on sensorless FOC vector frequency conversion control, and adopts sinusoidal current drive to minimize torque pulsation during motor operation; wherein, the controller adopts a segmented startup, including a rotor positioning stage, an open-loop control stage, and a closed-loop control stage. When in the rotor positioning stage, the current value is gradually increased until the rotor is positioned and then enters the open-loop control stage. When in the open-loop control stage, the current value is gradually increased until the target current value is reached and then enters the closed-loop control stage. When in the closed-loop control stage, the speed closed-loop and current closed-loop drive motors are used to perform dual closed-loop operation.

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] A compressor controller is installed outside the compressor housing, and the motor is installed inside the compressor housing. The controller is used to drive the motor to operate. The specific application environment is: mainly used for vehicle-mounted electronic scroll compressor control; maximum input power: 5000W; input voltage range: 150VDC-550VDC.

[0030] In this embodiment, the controller is based on sensorless FOC vector frequency conversion control and adopts sinusoidal current drive to minimize the torque pulsation during the operation of the motor; wherein, the controller adopts a segmented startup, including a rotor positioning stage, an open-loop control stage and a closed-loop control stage. When in the rotor positioning stage, the current value is gradually increased until the rotor is positioned and then enters the open-loop control stage. When in the open-loop control stage, the current value is gradually increased until the target current value is reached and then enters the closed-loop control stage. When in the closed-loop control stage, the speed closed-loop and current closed-loop drive motors are used to perform dual closed-loop operation; preferably, in this embodiment, when the motor starts, the first set of parameters (including positioning current and open-loop current) are used by default for startup. If the startup fails, it enters the restart state, and then the startup parameters are switched to the next set of parameters for restarting.

[0031] Preferably, in this embodiment, in order to improve the current sampling sensitivity and accuracy, see Figure 1 and Figure 2 As shown, the controller of this embodiment adopts a three-resistor sampling scheme. During the sampling process, the three-resistor current sampling needs to be performed when the lower bridge is turned on. Therefore, AD sampling needs to be coordinated with PWM. The controller uses the S32K14x microcontroller model chip. AD sampling delay and triggering can be achieved through the PDB module. PWM only needs to be synchronized with the PDB, and then the PDB module delays and triggers AD sampling.

[0032] Preferably, in this embodiment, the PWM carrier frequency of the controller is 16000 Hz, so that the electromagnetic noise is beyond the human hearing range, providing a comfortable experience. Further preferably, in this embodiment, each PWM sample is used to sample the bus voltage once, the sampling period is 62.5 μs, and the bus voltage filter coefficient is 8 (low-pass filter). To further facilitate control safety, preferably, in this embodiment, the controller's IPM has internal temperature detection and output, and the voltage value of the temperature detection port is read every 200 ms to calculate the IPM temperature for IPM over-temperature protection.

[0033] Preferably, in this embodiment, during the motor driving process, the controller is provided with current constraint control, wherein the current constraint control includes: setting three current values 、 、 , and satisfies The relationship between the d-axis current , q-axis current Composite output current , and there are ; When detected The motor speed is not allowed to continue to increase; when it is detected When the speed is detected, the speed decreases at a predetermined deceleration rate; When , the speed increases at a predetermined rate;

[0034] Preferably, in this embodiment, in this embodiment, during the motor driving process, the controller is provided with a field weakening control, wherein the field weakening control includes: respectively controlling the d-axis voltage , q-axis voltage The value is filtered, when the output voltage Exceeding the field weakening limit voltage When the output voltage is With the field weakening limit voltage The difference is calculated by PI operation to obtain the target working current I d .

[0035] Preferably, in this embodiment, during the startup process, when the actual motor speed is lower than 360 rpm, the low-speed d-axis current is allowed to Compensation, when the actual motor speed is higher than 480rpm, exit the low speed D axis current After successful startup, it is not allowed to enter the low-speed D-axis current again. compensation; further preferably, in this embodiment, when the low speed d axis current When the compensation value is 0 and the torque compensation amplitude is 0, the output current The amplitude of the current is obtained by linear interpolation after looking up the table. After determining the β angle, calculate 、 Specifically preferably, in this embodiment, the d-axis current , q-axis current The calculation formula is:

[0036] .

[0037] Preferably, in this embodiment, when the compressor is running, during the compression and suction process, the rotor load changes with the rotor position. At low speed, torque compensation is performed according to the rotor mechanical position to improve the load capacity of the compressor when running at low speed; the correspondence between the mechanical angle and the electrical angle is confirmed by mechanical angle locking, and then the current low-speed D-axis current is calculated based on the rotor mechanical angle by looking up the table. The size of the compensation; for specific optimization, take the three-pole compressor as an example, see Figure 3 The relationship between the motor load torque fluctuation and the angle is shown in the figure. Torque compensation can help to stabilize the motor during low-speed operation.

[0038] Preferably, in this embodiment, the controller is equipped with various fault detection mode controls, including low voltage fault, overvoltage fault, overcurrent fault, and stall fault. Among them, the low voltage fault specifically includes: detecting the bus voltage, and when the bus voltage is lower than 110VDC, setting a low voltage fault, stopping the motor drive, and the LED light flashing quickly; when the bus voltage is higher than 140VDC, the fault is recovered and the fault is cleared after 10 seconds;

[0039] Overvoltage fault includes: detecting bus voltage. When the bus voltage is higher than 560VDC, an overvoltage fault is set. After the fault occurs, the motor drive stops and the LED light flashes 6 times. When the bus voltage is lower than 530VDC, the fault is restored and cleared after 10 seconds.

[0040] Overcurrent fault includes: detecting the Fault port signal. When the Fault port goes low, the output is first shut down by the TimerBreak function, and then an overcurrent fault is set after an interrupt is triggered. After the fault occurs, the motor drive is stopped, the LED light flashes 3 times, and the fault is cleared after 10 seconds.

[0041] Stall faults include: When the target speed is not zero, but the actual motor speed is less than the minimum speed (tentatively set at 300 rpm) for 5 seconds, the motor is considered stalled. The motor rotor flux is detected. If the flux value is less than 50% (tentatively set) of the actual flux value, it is considered a flux abnormality. If the flux abnormality exceeds 50% within 5 seconds, the motor is considered stalled. After detecting a motor stall, the startup parameters are switched and the number of startup attempts is recorded. After reaching the maximum number of attempts (5), a motor stall fault is set, the motor drive is stopped, the LED light flashes 12 times, and the fault is cleared after 10 seconds. After the motor successfully starts for 20 consecutive seconds (tentatively set), the stall attempt count is cleared and the startup parameters are reset to the default parameters. After a fault shutdown or host computer shutdown, the stall attempt count is cleared and the startup parameters are reset to the default parameters.

[0042] Of course, the specific solutions for low voltage fault, over voltage fault, over current fault and stall fault involved in this application are not limited to the above-mentioned solutions, and other well-known control solutions can also be adopted, which will not be specifically explained in this embodiment.

[0043] Preferably, in this embodiment, each time the motor is started, the motor phase loss is detected, wherein, during the positioning phase of the starting process, when the current and angle are unchanged, the motor phase current is detected. , and perform low-pass filtering on the current, with a filter coefficient of 8;

[0044] ;

[0045] ;

[0046] ; ;

[0047] in, is the angle value at the end of the positioning phase, The choice of angle must ensure are not 0; further preferably, in this embodiment, in order to avoid phase loss, and When both are 0, no phase failure is detected. As a judgment value, when it is detected , When the deviation from the judgment value is not within the preset range, a phase loss fault reminder is set, and the motor drive is stopped after the fault; the LED light can flash for a few seconds to remind, and the phase loss fault is cleared after a few seconds.

[0048] This embodiment adopts sensorless FOC vector frequency conversion (SVPWM) control technology to achieve optimal performance control. In view of the sensitivity of compressor motor applications to noise, this application specifically adopts sinusoidal current drive, which can minimize the torque pulsation during motor operation. At the same time, when the motor starts; it adopts speed and current dual closed-loop control to have a faster response speed to changes in motor load, so that the motor running speed is more stable and the noise is reduced; and it is preferably combined with the introduction of current constraint control, weak magnetic control and phase loss detection to further facilitate the motor drive operation to be more stable and reliable and to reduce noise; at the same time, since the compressor used in this embodiment is a scroll compressor, one rotation of it is equivalent to a mechanical cycle, which will cause the output torque of the motor to have a large change, resulting in greater vibration when the motor runs at low speed, so during the low-speed operation of the motor, this embodiment specifically adds a low-speed d-axis current The compensation and torque compensation control functions are beneficial to the smooth operation of the motor during low-speed operation.

[0049] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

[0050] In addition, it should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A compressor controller is installed outside the compressor housing, and the motor is installed inside the compressor housing. The controller is used to drive the motor to operate, characterized in that Based on sensorless FOC vector frequency conversion control, sinusoidal current drive is used to minimize torque pulsation during motor operation. The controller adopts a segmented startup method, including a rotor positioning stage, an open-loop control stage, and a closed-loop control stage. When in the rotor positioning stage, the current value is gradually increased until the rotor is positioned, and then the open-loop control stage is entered. When in the open-loop control stage, the current value is gradually increased until the target current value is reached, and then the closed-loop control stage is entered. When in the closed-loop control stage, the speed closed-loop and current closed-loop drive motors are used for dual closed-loop operation. During startup, when the actual motor speed is lower than 360 rpm, low-speed D-axis current is allowed. Compensation, when the actual motor speed is higher than 480rpm, exit the low speed D axis current After successful startup, it is not allowed to enter the low-speed D-axis current again. compensate.

2. The controller according to claim 1, characterized in that , the PWM carrier frequency of the controller is 16000Hz.

3. The controller according to claim 1, characterized in that During the motor driving process, the controller is provided with a current constraint control, wherein the current constraint control includes: setting three current values 、 、 , and satisfies The relationship between the d-axis current , q-axis current Composite output current , and there are ; When detected The motor speed is not allowed to continue to increase; when it is detected When the speed is detected, the speed decreases at a predetermined deceleration rate; When the speed increases, it increases at a predetermined rate.

4. The controller according to claim 1, characterized in that During the motor driving process, the controller is provided with a field weakening control, wherein the field weakening control includes: respectively controlling the d-axis voltage , q-axis voltage The value is filtered, when the output voltage Exceeding the field weakening limit voltage When the output voltage is With the field weakening limit voltage The difference is calculated by PI operation to obtain the target working current I d .

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