CN105471340A - Starting structure, starting method and starting device of brushless doubly-fed motor - Google Patents

Abstract

Starting junction of brushless double-fed motorA starting structure comprises a frequency converter, wherein the output of the frequency converter is connected with a control winding P of a brushless doubly-fed motor_CPower winding P of brushless double-fed motor_pConnected to a power frequency power supply through a third switch KM3, in the invention, a frequency converter adopting a PWM (pulse width modulation) type is connected to a power winding for short-circuit of a power winding P_pThe short-circuit device is matched with software control, so that the frequency converter does not need to use a braking circuit, does not need to use a frequency sensitive rheostat (or an adjustable resistor) to reduce starting current, and does not need to use a starting resistor to short-circuit a control winding P_CThe soft start with low current and low cost of the brushless doubly-fed motor can be realized by only adding one short-circuit device on the hardware structure and matching with the starting method, and the starting structure of the brushless doubly-fed motor has simple structure and can reduce the volume of equipment.

Description

Starting structure, starting method and starting device of brushless doubly-fed motor

technical field

The present invention relates to the technical field of brushless doubly-fed motors, in particular to a start-up structure and a start-up method of a brushless doubly-fed motor. The method is completed by establishing a functional module framework and controlling a computer system by a computer program. These computer program instructions are stored in on a computer-readable storage medium.

Background technique

Brushless double-fed motor is a new type of motor. The brushless doubly-fed motor evolved from the cascaded motor, through two sets of stator windings (power winding P _p and control winding P _C ) and a specially designed rotor to achieve a brushless structure; through the control winding P _C Variable voltage and frequency conversion control realizes brushless double-fed motor variable speed constant frequency power generation or frequency conversion speed regulation electric operation. When running as a motor, there are starting issues involved. The starting of the brushless doubly-fed motor refers to the process of the motor rising from the speed of 0 to the natural synchronous speed N.

At present, the starting methods of brushless double-fed motors can be divided into synchronous starting and asynchronous starting. Synchronous starting means that the two sets of stator windings of brushless double-fed motors are simultaneously supplied with excitation sources. At this time, the motor exhibits the characteristics of a synchronous motor. Specifically, the power winding P _p processes frequency power excitation, the control winding P _C adds frequency conversion power excitation, the frequency of the control winding P _C increases from -50Hz to 0Hz, and the corresponding motor speed increases from 0 to N, thereby starting the motor. The problem with synchronous starting is that a full-power frequency converter is required, which is contrary to the original intention that the brushless doubly-fed motor can be controlled by a part-capacity frequency converter, so the mainstream starting method is still asynchronous starting.

The asynchronous start is the power winding P _p of the brushless doubly-fed motor plus the excitation source, and the control winding P _C is short-circuited or equipped with a special starting device. At this time, the motor conforms to the characteristics of an asynchronous motor. Asynchronous starting, especially the asynchronous starting of high-power brushless double-fed motors, needs to solve various problems caused by the same starting current as the asynchronous motor starting. In order to solve the problem of excessive starting current, the asynchronous starting method mainly adopted in the prior art is a starting method specially configured with a frequency-sensitive rheostat or an adjustable resistor. However, this method greatly increases the cost of motor supporting equipment and production and operation.

Contents of the invention

The purpose of the present invention is to avoid the deficiencies in the prior art and provide a start-up structure and start-up method of a brushless doubly-fed motor. The start-up structure cooperates with the start-up method to not only solve the problem of excessive start-up current, but also solve the There are many motor supporting equipment and high cost problems.

The object of the present invention is achieved through the following technical solutions:

A starting structure of a brushless double-fed motor is provided, including a frequency converter, the output of the frequency converter is connected to the control winding P _C of the brushless double-fed motor, and the power winding P _p of the brushless double-fed motor is connected to to the industrial frequency power supply. In the present invention, the frequency converter is a PWM type frequency converter, and the power winding P _p is connected with a short-circuit device for short-circuiting the power winding P _p .

The shorting device is a fourth contactor KM4, and the shorting contact KM4 is connected between the power winding _Pp and the third switch KM3.

The frequency converter includes a three-phase AC power uncontrolled rectifier circuit VR, a bus capacitor C connected to the output end of the uncontrolled rectifier circuit VR, a three-phase full-bridge inverter circuit VI connected to the output end of the bus capacitor C, and a three-phase full-bridge inverter The output terminal of the variable circuit VI is connected to the control winding P _C of the brushless doubly-fed motor.

The frequency converter also includes an input contactor KM1, a soft-start resistor R, a soft-start contactor KM2 and an input reactor L, and the three-phase AC power supply is sequentially connected to the input contactor KM1, the soft-start contactor KM2, the input reactor L and all The three-phase full-bridge uncontrolled rectifier circuit VR is described, and the soft-start resistor R is connected in parallel with the soft-start contactor KM2.

A method for starting a brushless doubly-fed motor, which is used to control the starting structure of the aforesaid brushless doubly-fed motor, comprising the following steps:

A: Short circuit the power winding P _p ;

_B : Gradually increase the voltage amplitude and frequency output from the PWM inverter to the control winding PC, and the speed of the brushless doubly-fed motor will gradually increase accordingly;

C: When the speed of the motor is close to the synchronous speed and stabilized, control the excitation of the PWM frequency converter output and the actual speed of the brushless doubly _- fed motor corresponding to the frequency of the control winding PC;

D: Connect the power winding P _p to the power frequency excitation, and drag the brushless double-fed motor from the asynchronous operation state of one group of excitation sources to the synchronous operation state of two groups of excitation sources acting at the same time;

E: When the motor enters the synchronous operation mode, control the PWM inverter to gradually reduce the output frequency until it outputs DC excitation. At this time, the brushless double-fed motor runs at the natural synchronous speed N, and the soft start of the motor is completed.

Step A is specifically to turn off the third switch KM3, and short-circuit the power winding _Pp by using a short-circuit device.

Step A is further to short-circuit the power winding P _p by opening the third switch KM3 and closing the fourth contactor KM4 connected between the power winding P _p and the third switch KM3 .

Step D is specifically to connect the power winding _Pp to power frequency excitation by opening the fourth contactor KM4 and closing the third switch KM3.

After step A and before step B, perform step A1: disconnect the second switch KM2 and the third switch KM3, close the contactor KM1, detect the DC bus voltage, and close the second switch KM2 when the DC bus voltage reaches a predetermined range , to complete the soft start of the PWM inverter.

Beneficial effects of the present invention:

The starting structure of a brushless doubly-fed motor of the present invention adopts a PWM (pulse width modulation) frequency converter, and a short-circuit device for short-circuiting the power winding P _p is connected to the power winding P _p . The device short-circuits the power winding P _p , and then controls the voltage amplitude and frequency output from the PWM inverter to the control winding P _C. After the speed of the brushless doubly-fed motor is stable, control the output frequency of the PWM inverter corresponding to the speed. , then connect the power winding P _p to the power frequency power supply, then control the frequency converter to gradually reduce the output frequency until the output DC excitation, then complete the starting structure of the brushless double-fed motor, the starting structure of the brushless double-fed motor of the present invention With this starting method, the circuit changes the current output to the control winding P _C by controlling the voltage amplitude and frequency output from the PWM inverter to the control winding P _C , thereby replacing the frequency-sensitive rheostat (or adjustable resistor) to reduce the start-up Current, no need to use frequency-sensitive rheostat (or adjustable resistor), and no need to use start-up resistor to short-circuit the control winding P _C , only need to add a short-circuit device in the hardware structure, with this start-up method, the brushless dual Feed motor small current, low-cost soft start, brushless doubly-fed motor start structure simple structure, can reduce equipment size.

Description of drawings

Utilize accompanying drawing to further illustrate the invention, but the embodiment in the accompanying drawing does not constitute any limitation to the present invention, for those of ordinary skill in the art, under the premise of not paying creative work, can also obtain other according to following accompanying drawing Attached picture.

Fig. 1 is a schematic circuit diagram of an asynchronous asynchronous structure of a brushless doubly-fed motor according to the present invention.

detailed description

The present invention is further described in conjunction with the following examples.

The starting structure of a brushless doubly-fed motor in this embodiment belongs to the asynchronous starting structure, as shown in Fig. Contactor KM2, input reactor L and three-phase full-bridge uncontrolled rectifier circuit VR, bus capacitor C connected to the output end of the rectifier circuit, three-phase full-bridge inverter circuit VI connected to the output end of bus capacitor C, three-phase full-bridge The output terminal of the bridge inverter circuit VI is connected to the control winding PC of the brushless doubly _- fed motor.

The three-phase AC power supply is sequentially connected to the first contactor KM1, the second soft-start contactor KM2, the input reactor L and the three-phase full-bridge uncontrolled rectifier circuit VR, and the soft-start resistance R is connected in parallel with the second soft-start contactor KM2 , the output terminal of the three-phase full-bridge uncontrolled rectifier circuit VR is connected to the bus capacitor C.

The output of the frequency converter is connected to the control winding P _C of the brushless double-fed motor, and the power winding P _p of the brushless double-fed motor is connected to the power frequency power supply through the third contactor KM3. In this embodiment, the frequency converter is In a PWM inverter, the power winding P _p is connected to a fourth contactor KM4, and the fourth contactor KM4 is connected between the power winding P _p and the third contactor KM3.

The control method of the starting structure of the above brushless doubly-fed motor is as follows:

Step A: Open the third contactor KM3, close the fourth contactor KM4 connected between the power winding P _p and the third contactor KM3 to realize the short circuit of the power winding P _p , the brushless doubly-fed motor at this time Equivalent to ordinary asynchronous motor;

Step A1: Open the second contactor KM2 and the third contactor KM3, close the contactor KM1, detect the DC bus voltage, when the DC bus voltage reaches the predetermined range, close KM2, and complete the soft start of the PWM inverter.

Step _B : Gradually increase the voltage amplitude and frequency output from the PWM inverter to the control winding PC, and the speed of the brushless doubly-fed motor will gradually increase accordingly;

Step C: when the speed of the motor is close to the synchronous speed and stabilized, control the PWM frequency converter output and the actual speed of the brushless doubly _- fed motor corresponding to the excitation of the frequency of the control winding PC;

Step D: Open the fourth contactor KM4, close the third contactor KM3 to realize the power winding _Pp access to power frequency excitation, and drag the brushless doubly-fed motor from the asynchronous operation state of one group of excitation sources to two groups Synchronous running state in which the excitation sources act at the same time;

Step E: After the motor enters the synchronous operation mode, control the PWM inverter to gradually reduce the output frequency until the output of DC excitation, at this time the brushless double-fed motor runs at the natural synchronous speed N, and the soft start of the motor is completed.

During the starting process, the switching state of the contactor remains unchanged.

The starting method of a brushless doubly-fed motor in this embodiment belongs to the asynchronous starting method, and the current output to the control winding P _C is changed by controlling the voltage amplitude and frequency output from the PWM frequency converter to the control winding P _C , thereby Replacing the frequency-sensitive rheostat (or adjustable resistor) to reduce the starting current can make it unnecessary to use the frequency-sensitive rheostat (or adjustable resistor), the frequency converter does not need to use a braking circuit, and there is no need to use a starting resistor to short-circuit the control winding P _C , only need to add a short-circuit device in the hardware structure, with this starting method, the small current and low-cost soft start of the brushless double-fed motor can be realized. The structure of the starting structure of the brushless double-fed motor is simple and can be reduced Equipment size.

In the method given in this paper, all or part of the steps can be completed by establishing a functional module framework and controlling the computer system by computer program instructions. These computer program instructions are stored on a computer readable storage medium.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting the protection scope of the present invention, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand , the technical solution of the present invention may be modified or equivalently replaced without departing from the spirit and scope of the technical solution of the present invention.

Claims (9)

1. a startup structure for brushless double-fed motor, comprises frequency converter, and the output of described frequency converter meets the controlled winding P of brushless double-fed motor _c, the power winding P of brushless double-fed motor _pbe connected to power frequency supply by the 3rd K switch M3, it is characterized in that: described frequency converter is PWM formula frequency converter, described power winding P _pbe connected to for short circuit power winding P _pshorted device.

2. the startup structure of a kind of brushless double-fed motor as claimed in claim 1, is characterized in that: described shorted device is the 4th K switch M4, and described 4th K switch M4 is connected to power winding P _pand between the 3rd K switch M3.

3. the startup structure of a kind of brushless double-fed motor as claimed in claim 1, it is characterized in that: the three-phase full-bridge inverting circuit VI that described frequency converter comprises three-phase alternating-current supply uncontrollable rectifier circuit VR, is connected to the bus capacitor C of uncontrollable rectifier circuit VR output, is connected to the output of bus capacitor C, the controlled winding P of the output termination brushless double-fed motor of three-phase full-bridge inverting circuit VI _c.

4. the startup structure of a kind of brushless double-fed motor as claimed in claim 3, it is characterized in that: described frequency converter also comprises input contactor KM1, soft start resistance R, soft start contactor KM2 and input reactance device L, three-phase alternating-current supply meets input contactor KM1, soft start contactor KM2, input reactance device L and described three phase full bridge uncontrollable rectifier circuit VR successively, and soft start resistance R is in parallel with soft start contactor KM2.

5. a starting drive for brushless double-fed motor, is characterized in that: for controlling the startup structure of a kind of brushless double-fed motor according to claim 1, comprise call successively as lower module:

Modules A: for by power winding P _pshort circuit;

Module B: export controlled winding P to for increasing PWM formula frequency converter gradually _cvoltage magnitude and frequency, the rotating speed of brushless double-fed motor can increase thereupon gradually;

Module C: for the rotating speed when motor close to synchronous speed and stable after, controls PWM formula frequency converter output controlled winding P corresponding to the actual speed of brushless double-fed motor _cthe excitation of frequency;

Module D: for by power winding P _pthe excitation of access power frequency, pulls brushless double-fed motor into synchronous operation state that two groups of driving sources act on simultaneously by the asynchronous operation state of one group of driving source;

Module E: after entering synchronous operation pattern when motor, control PWM formula frequency converter reduces output frequency gradually, until export continuous current excitation, now brushless double-fed motor operates in nature synchronous speed N, completes the soft start of motor.

6. the starting drive of a kind of brushless double-fed motor as claimed in claim 5, is characterized in that: the power winding P of brushless double-fed motor _pbe connected to power frequency supply by the 3rd K switch M3, modules A specifically disconnects the 3rd K switch M3, utilizes shorted device by power winding P _pshort circuit.

7. the starting drive of a kind of brushless double-fed motor as claimed in claim 6, is characterized in that: described shorted device is for being connected to power winding P _pand the 4th K switch M4 between the 3rd K switch M3, modules A is by disconnecting the 3rd K switch M3 further, is closed by the 4th K switch M4 and realizes power winding P _pshort circuit.

8. the starting drive of a kind of brushless double-fed motor as claimed in claim 7, is characterized in that: module D is particular by disconnection the 4th K switch M4, and closed 3rd K switch M3 realizes power winding P _pthe excitation of access power frequency.

9. the starting drive of a kind of brushless double-fed motor as claimed in claim 6, it is characterized in that: described rectification circuit also comprises input contactor KM1, soft start resistance R, soft start contactor KM2 and input reactance device L, three-phase alternating-current supply meets input contactor KM1 successively, soft start contactor KM2, input reactance device L and described three phase full bridge uncontrollable rectifier circuit VR, soft start resistance R is in parallel with soft start contactor KM2, after described modules A before module B, calling module A1: for disconnecting second switch KM2 and the 3rd K switch M3, closed contactor KM1, detect DC bus-bar voltage, after DC bus-bar voltage reaches preset range, closed second switch KM2, complete the soft start of PWM formula frequency converter.