Weak magnetic control circuit of motor

Abstract

The utility model provides a field weakening control circuit of a motor, which comprises an inverter, a controller, a field weakening circuit and a flux linkage observer, and is characterized in that the controller outputs target power of the motor and is connected with the input end of the field weakening circuit; the weak magnetic circuit comprises a weak magnetic ring for adjusting the output power of the inverter according to the target power, the input end of the weak magnetic ring is connected with the output end of the controller, and the output end of the weak magnetic ring is connected with the motor through a current ring, a modulator and the inverter which are connected in sequence; the input end of the flux linkage observer is connected with the motor to detect the flux linkage of the motor, one output end of the flux linkage observer is connected with the weak magnetic ring, and the other output end of the flux linkage observer is connected with the controller. The flux weakening control circuit provided by the utility model is provided with the flux linkage observer to detect the actual output power of the motor in real time.

Description

Technical Field

[0001] The utility model belongs to the technical field of motor control, and in particular relates to a weak magnetic control circuit of a motor. Background Art

[0002] For the variable frequency drive system, when entering the constant torque stage, due to the limitations of the rated voltage and bus voltage, under normal mode, the motor will not be able to achieve output requirements exceeding the rated output power. That is, for the variable frequency drive system, under the existing conventional control method, it can only run to the rated output power; for motors that have been running for a long time and have been worn, the maximum output power cannot even reach the rated output power and cannot meet the variable frequency control requirements.

[0003] In the prior art, in order to ensure that the actual output power of the motor is consistent with the target power, a weak magnetic ring is usually set in the control circuit. The weak magnetic ring has a built-in weak magnetic control algorithm, and the weak magnetic control of the motor is achieved through the weak magnetic ring and the weak magnetic algorithm.

[0004] The magnetic field weakening loop and the magnetic field weakening algorithm are widely used in the constant torque stage of the motor's magnetic field weakening control. However, in the conventional magnetic field weakening control circuit, the final output power of the motor is usually not monitored, and it is impossible to ensure whether the final output power of the motor is consistent with the target power. Utility Model Content

[0005] The technical problem to be solved by the utility model is to overcome the deficiencies of the prior art, provide a weak magnetic field control circuit of a motor, set a flux observer, and detect the actual output power of the motor in real time.

[0006] In order to achieve the purpose of the utility model, the utility model provides a weak magnetic field control circuit of a motor, and the technical solution adopted is:

[0007] A weak magnetic field control circuit for a motor includes an inverter, a controller, a weak magnetic field circuit and a flux observer, wherein:

[0008] A controller, which outputs the target power of the motor and is connected to the input end of the magnetic weakening circuit;

[0009] A magnetic weakening circuit includes a magnetic weakening loop for adjusting the output power of the inverter according to the target power, the input end of the magnetic weakening loop is connected to the output end of the controller, and the output end is connected to the motor through a current loop, a modulator, and an inverter connected in sequence;

[0010] The input end of the flux observer is connected to the motor to detect the flux of the motor, one output end is connected to the weak magnetic ring, and the other output end is connected to the controller.

[0011] Furthermore, a first regulator is arranged between the controller and the current loop, and the current loop includes a first current loop and a second current loop, the first current loop receives the q-axis current output by the weak magnetic loop and the first regulator respectively, and the second current loop receives the d-axis current output by the weak magnetic loop.

[0012] Furthermore, the weak magnetic circuit also includes a second regulator and a third regulator, the output end of the first current loop is connected to the second regulator, the output end of the second current loop is connected to the third regulator, and the output ends of the second regulator and the third regulator are respectively connected to the input end of the modulator.

[0013] Furthermore, the modulator includes an inverse Park converter and an SVPWM modulator connected in series, two input ends of the inverse Park converter are respectively connected to the output ends of the second regulator and the third regulator, and the output end of the SVPWM modulator is connected to the input end of the inverter.

[0014] Furthermore, the flux linkage observer is also connected to the input end of the inverse Park converter.

[0015] Furthermore, a bypass loop for inputting a d-axis current corresponding to the target power of the motor is also provided on the second current loop.

[0016] Furthermore, it also includes a collector for collecting the output power of the inverter, one end of the collector is connected to the circuit between the inverter and the motor, and the other end is connected to the weak magnetic ring.

[0017] Furthermore, the q-axis current output terminal of the collector is connected to the weak magnetic ring and the current ring respectively.

[0018] Furthermore, the collector includes a Park converter and a Clark converter connected in series, the output end of the Park converter is connected to the input end of the weak magnetic ring, and the input end of the Clark converter is connected to the circuit between the inverter and the motor.

[0019] Furthermore, the flux linkage observer is also connected to the input end of the Park converter.

[0020] In summary, the weak magnetic field control circuit of a motor provided by the utility model has the following beneficial effects compared with the prior art:

[0021] 1. Set up a weak magnetic circuit, perform weak magnetic control by detecting the current relationship between the inverter output current and the target power, output control current, and adjust the inverter output current simultaneously with the main control circuit to make the motor reach the target speed;

[0022] 2. It is not only applicable to the inverter PN side connected to large electrolytic capacitors (PN voltage is stable and weak magnetic), but also applicable to the inverter PN side connected to small film capacitors (PN voltage pulsation is very large), with a wide range of applications;

[0023] 3. By setting up a flux observer, the real-time speed of the motor can be detected, further improving the effect of weak magnetic control. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 : A motor control circuit diagram provided by the utility model.

[0025] Among them, inverter 1, permanent magnet synchronous motor 2, flux observer 3, Clark converter 4, Park converter 5, weak magnetic loop 6, first regulator 7-1, second regulator 7-2, third regulator 7-3, inverse Park converter 8, SVPWM modulator 9, first current loop 10-1, second current loop 10-2, capacitor 12. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the utility model clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the utility model. The following embodiments are used to illustrate the utility model but are not used to limit the scope of the utility model.

[0027] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0028] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0029] The utility model provides a weak magnetic field control circuit of a motor, comprising an inverter 1, a controller (not shown in the figure), a weak magnetic field circuit and a flux observer 3, wherein:

[0030] A controller outputs a target power of the motor and is connected to an input terminal of the magnetic field weakening circuit;

[0031] A weak magnetic circuit, comprising a weak magnetic ring 6 for adjusting the output power of the inverter 1 according to the target power, wherein the input end of the weak magnetic ring 6 is connected to the output end of the controller, and the output end is connected to the motor through a current loop, a modulator, and the inverter 1 which are connected in sequence;

[0032] An input end of the flux observer 3 is connected to the motor to detect the flux of the motor, an output end is connected to the weak magnetic ring 6, and the other output end is connected to the controller.

[0033] In this embodiment, a permanent magnet synchronous motor is taken as an example to introduce the specific contents of a weak magnetic field control circuit of a motor provided by the utility model.

[0034] like Figure 1 As shown, the utility model provides a weak magnetic field control circuit of a motor, the inverter 1 is a three-phase inverter, the output end is connected to the permanent magnet synchronous motor 2, and the voltage and current (power) corresponding to the target power are provided to the permanent magnet synchronous motor 2, and the input end is connected to the weak magnetic field circuit, and is connected to the controller through the weak magnetic field circuit. Through weak magnetic field control, the actual power of the permanent magnet synchronous motor 2 is equal to the target power.

[0035] A large electrolytic capacitor or a small film capacitor (not shown in the figure) can be connected to the PN side of the inverter 1 to adjust the output voltage of the inverter 1 .

[0036] The input end of the permanent magnet synchronous motor 2 is connected to the output end of the inverter 1, and the output end is connected to one or more loads (not shown in the figure) to provide power for the loads. The controller determines the target power of the permanent magnet synchronous motor 2 according to the operating requirements (loads) of all loads, and sends a control signal to the inverter 1 through a weak magnetic circuit. The control signal includes but is not limited to the speed, voltage, current, power, etc. of the permanent magnet synchronous motor 2, so that the output power of the permanent magnet synchronous motor 2 can meet the operating requirements of all loads, even if the actual output power of the permanent magnet synchronous motor 2 is equivalent to the target power.

[0037] The controller (not shown in the figure) adjusts the target power (rotor speed, voltage, and current of the motor) of the permanent magnet synchronous motor 2 according to the operating load of each load to control the real-time state of the load so that the load meets the target demand. The number of loads and the load state are different, the load of the permanent magnet synchronous motor 2 is different, the target power is different, and the output voltage and current of the inverter 1 are different.

[0038] Under normal conditions, the controller can directly control the output of the inverter 1. In the constant power area, after entering the weak magnetic state, the weak magnetic circuit controls the permanent magnet synchronous motor 2 to weaken the magnetic field, so that the actual output power of the permanent magnet synchronous motor 2 is equivalent to the target power.

[0039] The input end of the magnetic field weakening circuit is connected to the output end of the controller, and is parsed into a q-axis current control signal corresponding to the permanent magnet synchronous motor 2 according to the target power of the controller, and is sent to the inverter 1.

[0040] In this embodiment, the weak magnetic circuit includes a weak magnetic ring 6, the input end of the weak magnetic ring 6 is connected to the controller, and the output end is electrically connected to the current loop 10, the modulator, the inverter 1 and the permanent magnet synchronous motor 2 in sequence. The weak magnetic ring 6 has a built-in weak magnetic algorithm and is the main component for detecting entering the weak magnetic state and performing weak magnetic control. This is a conventional technology and is not subject to any restrictions or requirements. The weak magnetic ring 6 is not the focus of improvement of the utility model. Any existing or future technology that may appear is applicable to the control circuit provided in this application.

[0041] Specifically, the magnetic field weakening circuit includes a current loop 10 and a modulator connected in series, which resolves the target power of the controller into a q-axis target current corresponding to the permanent magnet synchronous motor 2, and converts it into an output voltage value corresponding to the inverter 1 through the modulator. In the present application, the magnetic field weakening circuit resolves the target power into an output voltage value corresponding to the inverter 1. In practical applications, the target power can be converted into a current, voltage, and power that can control the operating state of the permanent magnet synchronous motor 2 without any restrictions or requirements.

[0042] like Figure 1 As shown, the current loop 10 includes a first current loop 10-1 and a second current loop 10-2 connected in parallel, the input end of the first current loop 10-1 is connected to the output end of the controller, and the output end is connected to the modulator; the modulator includes a regulator 7 and a series-connected inverse Park converter 8 and SVPWM converter 9, the input end of the regulator 7 is connected to the output end of the current loop 10, and the output end of the SVPWM converter 9 is connected to the input end of the inverter 1. One output end of the weak magnetic loop 6 is connected to one input end of the first current loop 10-1.

[0043] A first regulator 7 - 1 is provided between the first current loop 10 - 1 and the controller, which resolves the target output power output by the controller into a q-axis target current corresponding to the permanent magnet electric stepper motor 2 and sends it to the first current loop 10 - 1 .

[0044] Correspondingly, the regulator includes a second regulator 7-2 and a third regulator 7-3 connected in parallel, the input end of the second regulator 7-2 is connected to the output end of the first current loop 10-1, so that the first current loop 10-1 receives the q-axis current output by the weak magnetic ring 6 and the first regulator 7-1 respectively; the input end of the third regulator 7-3 is connected to the output end of the second current loop 10-2, one output end of the weak magnetic ring 6 is connected to an input end of the second current loop 10-2, and a bypass loop is provided on the second current loop 10-2, and the d-axis current corresponding to the target power of the permanent magnet synchronous motor 2 is input into the second current loop 10-2, so that the second current loop simultaneously receives the d-axis current output by the weak magnetic ring 6 and the controller.

[0045] The two input ends of the inverse Park converter 8 are respectively connected to the output ends of the second regulator 7-2 and the third regulator 7-3, and the output end is connected to the input end of the inverter 1 through the SVPWM converter 9, and the target work of the permanent magnet synchronous motor 2 obtained after the regulator is transmitted to the inverter in the corresponding voltage.

[0046] The weak magnetic circuit also includes a collector, whose input end is connected to the circuit between the inverter 1 and the permanent magnet synchronous motor 2, and whose output end is connected to the weak magnetic ring 6 to collect the actual output power of the inverter 1 (which can be expressed as a current value).

[0047] The collector includes a Park converter 5 and a Clark converter 4 connected in series, the output end of the Park converter 5 is connected to the input end of the weak magnetic ring 6 , and the input end of the Clark converter 4 is connected to the circuit between the inverter 1 and the permanent magnet synchronous motor 2 .

[0048] The Clark converter 4 collects the three-phase current value output by the inverter 1, converts it into a two-phase current value and sends it to the Park converter 5. The Park converter 5 converts the collected current value into the q-axis corresponding to the permanent magnet synchronous motor 2 and sends it to the weak magnetic ring 6 and the first current loop 10-1, and the d-axis current is sent to the weak magnetic ring 6 and the second current loop 10-2.

[0049] Furthermore, the weak magnetic field control circuit of a motor provided by the utility model also includes a flux observer 3, the input end of the flux observer 3 is connected to the permanent magnet synchronous motor 2, and the flux of the permanent magnet synchronous motor 2 is detected, that is, the speed and rotor position of the permanent magnet synchronous motor 2, that is, the rotor angle, are collected in real time. And there are three output ends, two of which are respectively connected to the first regulator 7-1 and the weak magnetic ring 6 to send the real-time speed of the permanent magnet synchronous motor 2; the flux observer 3 is also connected to the inverse Park converter 8 and the input end of the Park converter 5 through another output end, and the real-time rotor position of the permanent magnet electric stepping motor 2, that is, the rotor angle.

[0050] As in the circuit described above, the controller determines the target power of the motor according to the workload of all loads. The target power is input into the first regulator 7-1 by the controller, and the q-axis current (target current value) obtained enters the inverse Park converter 8 after passing through the first current loop 10-1 and the second regulator 7-2; the d-axis current corresponding to the target power is input into the second current loop 10-2 and the third regulator 7-3 through the bypass loop, and then enters the inverse Park converter 8; the d-axis current and q-axis current corresponding to the target power are converted into corresponding d-axis voltage and q-axis voltage through the third regulator 7-3 and the second regulator 7-2 respectively, and then are converted into corresponding d-axis voltage and q-axis voltage through the inverse Park converter 8 and modulated by the SVPWM modulator 9, and then input into the inverter 1 to control the output voltage of the inverter 1.

[0051] The Clark converter 4 collects the real-time output three-phase current value of the inverter 1 and converts it into the d-axis current and q-axis current corresponding to the permanent magnet synchronous motor 2. After passing through the Park converter 5, it is transmitted to the weak magnetic ring 6; at the same time, the q-axis current is transmitted to the first current loop 10-1, and the d-axis current is transmitted to the second current loop 10-2.

[0052] The flux observer 3 detects the real-time speed and rotor angle of the permanent magnet synchronous motor 2, and sends the rotor angle to the inverse Park converter 8 and the Park converter 5 through the circuit, and sends the speed to the weak magnetic ring 6 and the first regulator 7-1.

[0053] In the present utility model, when the permanent magnet synchronous motor 2 is in the constant torque zone, that is, the output voltage of the inverter 1 is sufficient to make the permanent magnet synchronous motor 2 reach the target power, the collector only collects the output current of the inverter, the weak magnetic ring 6 does not work, and the output voltage of the inverter 1 is controlled by the main control circuit so that the permanent magnet synchronous motor 1 can drive the load to achieve the set load; when the output voltage of the inverter 1 is not enough to support the target power, that is, the output voltage of the inverter 1 is less than the voltage corresponding to the target power, the permanent magnet synchronous motor 2 cannot drive the load to reach the set load, the permanent magnet synchronous motor 2 enters the constant power zone, the weak magnetic ring 6 is activated, the permanent magnet synchronous motor 2 enters the weak magnetic control, and the weak magnetic control circuit cooperates with the main control circuit to achieve the expected target speed (target power).

[0054] It is a conventional technology to realize weak magnetic control by using a weak magnetic ring. Any existing or future weak magnetic ring that can be realized to perform weak magnetic control is applicable to the control circuit of the utility model.

[0055] The weak magnetic ring 6, each regulator, each current loop and other parts are integrated with the controller. The controller can be the controller of the product in which the permanent magnet synchronous motor 2 is located, which can control the permanent magnet synchronous motor 2 and other components at the same time, and can also be integrated with the permanent magnet synchronous motor 2 to control the voltage and current output of the permanent magnet synchronous motor 2 to achieve a target power greater than or equal to the rated power to control the actual output power of the inverter 1, thereby controlling the speed of the permanent magnet synchronous motor 2.

[0056] In summary, the motor control circuit provided by the utility model has the following beneficial effects compared with the prior art:

[0057] 1. Set up a weak magnetic control circuit, perform weak magnetic control by detecting the current relationship between the inverter output current and the target power, output control current, and adjust the inverter output current simultaneously with the main control circuit to make the motor reach the target speed;

[0058] 2. It is not only applicable to the inverter PN side connected to large electrolytic capacitors (PN voltage is stable and weak magnetic), but also applicable to the inverter PN side connected to small film capacitors (PN voltage pulsation is very large), with a wide range of applications;

[0059] 3. By setting up a flux observer, the real-time speed of the motor can be detected, further improving the effect of weak magnetic control.

[0060] The above is only a preferred embodiment of the present invention, and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with this patent can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content suggested above without departing from the scope of the technical solution of the present invention. The implementation schemes in the above embodiments can also be further combined or replaced. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the present invention.

Claims

1. A weak magnetic field control circuit for a motor, characterized in that: It includes an inverter, a controller, a flux weakening circuit and a flux observer, among which: A controller, which outputs the target power of the motor and is connected to the input end of the magnetic weakening circuit; A magnetic weakening circuit includes a magnetic weakening loop for adjusting the output power of the inverter according to the target power, the input end of the magnetic weakening loop is connected to the output end of the controller, and the output end is connected to the motor through a current loop, a modulator, and an inverter connected in sequence; The input end of the flux observer is connected to the motor to detect the flux of the motor, one output end is connected to the weak magnetic ring, and the other output end is connected to the controller.

2. A motor weak magnetic field control circuit as claimed in claim 1, characterized in that: A first regulator is arranged between the controller and the current loop, and the current loop includes a first current loop and a second current loop, the first current loop receives the q-axis current output by the weak magnetic loop and the first regulator respectively, and the second current loop receives the d-axis current output by the weak magnetic loop.

3. A weak magnetic field control circuit for a motor as claimed in claim 2, characterized in that: The weak magnetic circuit also includes a second regulator and a third regulator, the output end of the first current loop is connected to the second regulator, the output end of the second current loop is connected to the third regulator, and the output ends of the second regulator and the third regulator are respectively connected to the input end of the modulator.

4. A weak magnetic field control circuit for a motor as claimed in claim 3, characterized in that: The modulator includes an inverse Park converter and an SVPWM modulator connected in series, two input ends of the inverse Park converter are respectively connected to the output ends of the second regulator and the third regulator, and the output end of the SVPWM modulator is connected to the input end of the inverter.

5. A weak magnetic field control circuit for a motor as claimed in claim 4, characterized in that: The flux linkage observer is also connected to the input end of the inverse Park converter.

6. A weak magnetic field control circuit for a motor as claimed in claim 2, characterized in that: The second current loop is also provided with a bypass loop for inputting a d-axis current corresponding to the motor target power.

7. A weak magnetic field control circuit for a motor as claimed in claim 1, characterized in that: It also includes a collector for collecting the output power of the inverter, one end of the collector is connected to the circuit between the inverter and the motor, and the other end is connected to the weak magnetic ring.

8. A weak magnetic field control circuit for a motor as claimed in claim 7, characterized in that: The q-axis current output end of the collector is connected to the weak magnetic ring and the current ring respectively.

9. A weak magnetic field control circuit for a motor as claimed in claim 7, characterized in that: The collector comprises a Park converter and a Clark converter connected in series, the output end of the Park converter is connected to the input end of the weak magnetic ring, and the input end of the Clark converter is connected to the circuit between the inverter and the motor.

10. A weak magnetic field control circuit for a motor as claimed in claim 9, characterized in that: The flux linkage observer is also connected to the input end of the Park converter.

Images