CN106452218A - Modularized three-phase multi-end motor and driving control method thereof - Google Patents

Abstract

The invention discloses a modularized three-phase multi-terminal motor and its drive control method, comprising: a three-phase multi-terminal motor body, a carrier phase-shifting pulse width modulation circuit for driving the motor, a controller and a driving circuit; a three-phase multi-terminal motor The main body is composed of two oppositely arranged and concentric stators and rotors; the coils embedded in the stator slots of the motor form multiple sets of three-phase symmetrical windings according to the spatial position, and each set of three-phase winding modules is connected to an independent three-phase inverter. The PWM carrier of each three-phase inverter is shifted in sequence in sequence, and all inverters are driven in a certain way to provide current for the entire motor system. When the motor is running, the corresponding electromagnetic torque generated by each set of winding modules is superimposed on the rotor. Form the total electromagnetic torque. In the present invention, the motor body is designed as a multi-three-phase module structure, so that it has better fault-tolerant performance. By combining the multi-inverter common driving mode with the PWM carrier phase-shift control method, the torque ripple introduced by PWM in the total electromagnetic torque of the motor system is significantly reduced.

Description

A modular three-phase multi-terminal motor and its drive control method

technical field

The invention belongs to the field of AC motors and drive control, and more specifically relates to a modular three-phase multi-terminal motor and a drive control method thereof.

Background technique

With the development of modern motors, power electronics and control technology, AC motor frequency conversion speed regulation systems driven by power electronics inverters have been widely used in the fields of servo and traffic traction. In the application of high-power AC motors, due to the limited power level of the switching tubes, it is difficult for a single three-phase inverter to meet the driving requirements. In this case, the parallel structure of multiple inverters is often used, and this structure usually introduces New problems such as circulation between bridge arms. In addition, the power electronic inverter used to drive the AC motor works in the pulse width modulation (Pulse Width Modulation, PWM) mode, and the switching current ripple brought by PWM will correspond to the electromagnetic torque ripple of the switching frequency, thus giving Motors bring torque ripple and vibration noise associated with PWM. These two problems in the AC motor speed control system hinder its application in high-performance occasions.

Contents of the invention

Aiming at the defects of the prior art, the purpose of the present invention is to provide a new modular three-phase multi-terminal motor and its drive control method, aiming at realizing the high-power motor drive requirements while solving the problems related to PWM in the prior art. Torque ripple and vibration noise problems.

The present invention provides a modular three-phase multi-terminal motor, comprising: a three-phase multi-terminal motor body, which is used to drive the drive control structure of the motor; the three-phase multi-terminal motor body includes: n modular stators and a rotor; stator pole pairs The number is consistent with the number of pole pairs of the rotor; each modular stator includes a complete set of three-phase windings, and when the windings pass current, they can generate corresponding electromagnetic torques on the rotors. The total electromagnetic torque is obtained by superimposing on the rotor; the drive control structure includes: a drive circuit, a carrier phase-shift pulse width modulation circuit and a controller; the alternating currents in multiple windings in the three-phase multi-terminal motor body respectively generate a rotating magnetic field and jointly The rotor permanent magnet acts to generate the required electromagnetic torque; the input terminal of the drive circuit is connected to the DC bus power supply, and the output terminal is connected to each winding of the motor. Each drive circuit is controlled by the carrier phase-shift pulse width modulation circuit and the controller. signal; the carrier phase-shifting pulse width modulation circuit is used to generate multiple phase-shifting carrier signals; the controller includes: a speed controller and a current controller, which are used to control and adjust the motor speed and current respectively.

Furthermore, the rotor is a permanent magnet rotor or a wound rotor.

Furthermore, the stator winding is concentrated winding with fractional slots or distributed winding with integer slots.

Furthermore, the waveforms of the corresponding phases of the n three-phase stator modules are the same, and the carrier signal corresponding to each drive circuit is a symmetrical triangular wave sequence with a carrier period of Ts; the waveforms of each carrier signal are the same, but the phases are different, that is The eliminated torque m-time switching ripple, according to the order of modules 1 to n, the PWM carrier is phase-shifted by Ts/n/m time.

Furthermore, the carrier phase-shift pulse width modulation circuit includes: a triangular wave generator and a phase shift controller, the triangular wave generator is used to generate the carrier required for modulation; the phase shift controller is used to adjust the initial phase of the triangular wave accordingly.

The present invention also provides a driving control method based on the above-mentioned modular three-phase multi-terminal motor, comprising the following steps:

After subtracting the reference speed from the measured speed of the motor, the torque reference current is generated after being processed by the speed controller;

The torque reference current is divided into n equal parts and used as the current command value of n current controllers, and the measured three-phase current is fed back to the current controller;

n current controllers output the voltage duty cycle of n sets of three-phase windings, and compare the voltage duty cycle with the phase-shifted carrier corresponding to each set of three-phase windings to obtain the PWM switch corresponding to each set of three-phase windings Signal;

By sending the PWM switching signal to the three-phase inverter and controlling the modular three-phase multi-terminal motor to rotate as required.

Furthermore, according to the m times of torque ripple to be eliminated, the carrier signals of every two adjacent current controllers are phase-shifted by 1/n/m carrier cycles.

By designing the three-phase multi-terminal motor system as a multi-three-phase module structure, it has better fault-tolerant performance. At the same time, by combining the multi-inverter common driving mode with the PWM carrier phase-shift control method, the torque ripple introduced by PWM in the total electromagnetic torque of the motor system can be significantly reduced.

Through the above technical solution conceived by the present invention, compared with the prior art, the motor is made into multi-terminal modularization and driven by multiple inverters at the same time. Since each inverter can control the current ripple independently, it can achieve large Power drive while reducing torque ripple and vibration noise.

Description of drawings

Fig. 1 is a schematic diagram of the basic topology of a modular three-phase multi-terminal motor body realized according to the present invention;

Fig. 2 is the typical design result of the modularized three-phase multi-terminal motor body realized according to the present invention;

Figure 3 is a schematic diagram of the distribution of magnetic lines of force and the wiring of the windings of a modular three-phase multi-terminal motor;

Fig. 4 is the driving circuit structural diagram of the single module motor realized according to the present invention;

Fig. 5 is a block diagram of a motor system control drive circuit realized according to the present invention;

Fig. 6 is a modular three-phase multi-terminal motor control block diagram realized according to the present invention;

Fig. 7 is the carrier phase-shift PWM method realized according to the present invention;

Fig. 8 is a synthetic diagram of torque ripple when each drive circuit adopts a unified carrier;

Fig. 9 is a synthesizing diagram of torque ripple space vector under the carrier phase-shifting PWM method realized according to the present invention;

Fig. 10 is a schematic diagram of the implementation flow of the drive control method of the modularized three-phase multi-terminal motor provided by the present invention.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention.

The present invention provides a modular three-phase multi-terminal motor system, comprising: a three-phase multi-terminal motor body, a drive control structure for driving the motor, wherein the drive control structure includes: a drive circuit, a carrier phase-shift pulse width modulation circuit and a controller ; Among them, the three-phase multi-terminal motor body includes a stator side that is divided into multiple identical windings and a permanent magnet rotor, and the alternating currents in the multiple windings respectively generate rotating magnetic fields and interact with the rotor permanent magnets to generate the required electromagnetic torque; the drive circuit The input terminal is connected to the DC bus power supply, and the output terminal is connected to each winding of the motor. Each drive circuit is given a switching action control signal by the carrier phase-shifting pulse width modulation circuit and the controller; the carrier phase-shifting pulse width modulation circuit includes: a triangular wave generator and A phase-shifting controller is used to generate multiple phase-shifting carrier signals as required; the controller includes: a speed controller and a current controller, and the controller adopts a PI regulator structure, which are respectively used for the control and adjustment of the motor speed and current;

In the invention, the AC motor is designed into a multi-three-phase module structure, so that it has better modular structure and fault-tolerant performance. On this basis, the multi-inverter independent drive mode is adopted, and the PWM carrier of each branch inverter is sequentially phase-shifted in the control method, so that the switching current ripple of the same phase of each inverter is sequentially phased. Phase shifting finally makes the synthetic electromagnetic torque switch ripples on the rotor cancel each other when they are synthesized in space, greatly reducing the motor torque ripple and vibration noise introduced by PWM modulation.

In the present invention, the motor is composed of multiple independent three-phase modules; the electromagnetic coupling between the three-phase modules of the motor is weak, and each three-phase module is driven and controlled by an independent inverter, and the fault can be removed under fault conditions module, and the remaining modules continue to work, which can achieve good fault-tolerant performance. The inverter carrier wave of each three-phase module is phase-shifted sequentially, so that the PWM ripples of the synthesized electromagnetic torque cancel each other, and the torque ripple is significantly reduced.

In order to further illustrate the modularized three-phase multi-terminal motor and its driving control method provided by the embodiment of the present invention, it is now described in detail in conjunction with the accompanying drawings and specific examples as follows:

As shown in FIG. 1 , a modular three-phase multi-terminal motor includes: n modular stators 1 (n is any natural number) and a rotor 2 . The rotor 2 can be a permanent magnet rotor, or an AC motor rotor in other forms. The number of stator pole pairs is the same as that of the rotor pole pairs. Each modular stator includes a complete set of three-phase windings. When the windings pass current, they can generate corresponding electromagnetic torques on the rotor. The electromagnetic torques generated by each stator module are superimposed on the rotor to obtain the total electromagnetic torque. The back EMF waveforms of the corresponding phases of the n three-phase stator modules are consistent. The electromagnetic coupling between the n three-phase stator modules is very small.

As shown in FIG. 2 , taking n=4 as an example, a specific embodiment of a modular three-phase multi-terminal motor topology is designed. This embodiment consists of a stator 1 with 12 slots and a rotor 2 with permanent magnets with 4 pairs of poles. Around the 12 teeth of the stator 1, 12 independent non-overlapping coils are embedded. These independent coils form four sets of three-phase symmetrical windings, and there is no electromagnetic coupling between the corresponding phases of each set of windings, so the stator 1 can be regarded as four independent modular stators. The four sets of three-phase windings of the motor topology are respectively driven by four sets of three-phase inverters.

As shown in Figure 3, it is a specific winding phase composition method of the three-phase multi-terminal motor topology embodiment given in Figure 2, and a schematic diagram of the magnetic field distribution at a specific rotor position, where A1, B1, and C1 are the first set The three-phase coils of the winding, A2, B2, and C2 are the three-phase coils of the second set of windings, and so on. From the distribution of the magnetic field, it can be clearly seen that the magnetic fields linked by the coils of the corresponding phases of the four sets of windings are exactly the same, so that the back EMF waveforms of the corresponding phases are also completely consistent, so the four sets of windings can use four sets of three-phase inverters to work together drive control method.

As shown in Fig. 4, n-phase motor, kth module, 1≤k≤n; each modular stator is driven by a three-phase half-bridge inverter. Each inverter includes three bridge arms, and each bridge arm is composed of two power electronic bidirectional switching devices connected in series, and the midpoint of the bridge arm is connected to the terminal of the corresponding phase of the corresponding module. Each driving circuit can generate a three-phase sinusoidal current in the corresponding stator module to act on the rotor to generate corresponding electromagnetic torque.

As shown in Figure 5, the overall drive control structure of the modular three-phase multi-terminal motor includes: n drive circuits, controllers and corresponding carrier phase-shift pulse width modulation circuits. The DC sides of the n driving circuits may be independent DC power sources or a shared DC power source. The AC output sides of the n drive circuits are connected to n sets of three-phase stator windings of the modular three-phase multi-terminal motor to generate n sets of three-phase currents. Since the counter electromotive force of each stator module is consistent, the three-phase current of each module is also correspondingly consistent in a steady state. The controller collects the motor speed and rotor position information, as well as the current of each winding, realizes the double closed-loop control of the speed and current, and then sends the pulse width modulation (PWM) signal to each driving circuit to realize the control function.

As shown in Figure 6, the controller of a modular three-phase multi-terminal motor includes: a speed controller and a current controller, in which the control signals form two closed loops, that is, the speed controller, the current controller, the drive circuit and the motor speed feedback signal The outer speed closed loop composed of the outer loop and the inner current closed loop composed of the current controller, the drive circuit and the motor current feedback signal. In the outer loop, the reference speed is subtracted from the measured speed of the motor to generate a torque reference current through the speed controller. After the reference current is divided into n equal parts, they are respectively used as current command values of n current controllers. PWM signals output by n current controllers are used to drive n driving circuits. Wherein, each group of PWM is realized by comparing the duty cycle output by the current controller with the corresponding carrier.

Fig. 7 is a schematic diagram of carrier control distribution of n stator modules of a modular three-phase multi-terminal motor. Each carrier is a symmetrical triangular wave sequence with switching period Ts. According to the 1~n sets of windings defined in sequence, according to the torque m times of switching ripples to be eliminated, the PWM carrier is phase-shifted by Ts/n/m in turn, that is, the carrier waves of n sets of drive circuits are equidistantly phase-shifted. Since the reference currents of the current controllers corresponding to each set of windings are consistent at all times, the output duty ratios of the current controllers are also consistent, but the carrier waves of the driving circuits are phase-shifted. Therefore, the fundamental wave current output by each set of windings is consistent, and only the switching subharmonics are phase-shifted sequentially. Corresponding to the electromagnetic torque generated by each set of windings on the motor, the average torque is the same, and the m-time torque ripple generated by PWM realizes the phase shift, so that the final superposition greatly reduces the total electromagnetic torque ripple.

Fig. 8 is a synthesizing schematic diagram of the electromagnetic torque ripple at the switching frequency of each module when the carrier wave corresponding to each module of the modularized three-phase multi-terminal motor has no phase shift. Since each module adopts the same carrier, the torque ripples Tq1~Tqn are consistent in time phase. Therefore, the torque ripple of each module is added algebraically to obtain the total torque ripple, that is, the total torque ripple is equal to n times of the torque ripple of each module.

Fig. 9 is a schematic diagram of synthesizing torque ripple of PWM switching frequency obtained by the carrier wave of the modularized three-phase multi-terminal motor under the phase-shift mode (Fig. 7) proposed by the present invention. Since the carrier wave of each module is phase-shifted by Ts/n/m in sequence, it is equivalent to a phase shift of 2π/n/m at the switching frequency, so Tq1~Tqn are phase-shifted by 2π/n/m in sequence, and the vector The synthesized m times of torque ripple is theoretically equal to zero. Therefore, the torque ripple is significantly suppressed.

Figure 10 is the working flow chart of the whole program. The difference between the speed command and the feedback speed signal is input to the speed controller, and the torque current reference value is given after calculation. The reference value of the torque current is taken as the command value of each current controller after being divided into n equal parts, and the difference with the current feedback value is input into the current controller. After calculation, each current controller gives the three-phase voltage of each winding respectively. Duty ratio, these duty ratios are compared with the corresponding phase-shifted carrier to obtain the switching signal of the inverter and output to the drive circuit to generate a corresponding voltage to act on the motor so as to realize the control of the motor speed and torque.

The modularized three-phase multi-terminal motor structure and its carrier phase-shift control method in the present invention are suitable for applications requiring medium and high power, high fault tolerance, and strict requirements on torque ripple and vibration noise.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (7)

1. A modular three-phase multi-terminal motor, characterized in that, comprising: a three-phase multi-terminal motor body, used to drive the drive control structure of the motor; The three-phase multi-terminal motor body includes: n modular stators (1) and a rotor (2); the number of pole pairs of the stator is consistent with the number of pole pairs of the rotor; each modular stator includes a A complete set of three-phase windings. When the windings pass current, they can generate corresponding electromagnetic torques on the rotor. The electromagnetic torques generated by each stator module are superimposed on the rotor to obtain the total electromagnetic torque; n is any natural number; The drive control structure includes: a drive circuit, a carrier phase-shift pulse width modulation circuit and a controller; the alternating currents in the multiple windings in the three-phase multi-terminal motor body respectively generate rotating magnetic fields and interact with the rotor permanent magnets to generate the required electromagnetic Torque; the input terminal of the drive circuit is connected to the DC bus power supply, and the output terminal is connected to each winding of the motor. Each drive circuit is given a switching action control signal by the carrier phase-shift pulse width modulation circuit and the controller; the carrier phase-shift pulse The wide modulation circuit is used to generate multiple required phase-shifted carrier signals; the controller includes: a speed controller and a current controller, which are used to control and adjust the motor speed and current respectively. 2. The modular three-phase multi-terminal motor according to claim 1, characterized in that, the rotor (2) is a permanent magnet rotor or a wound rotor. 3. The modularized three-phase multi-terminal motor according to claim 1 or 2, wherein the stator winding is a concentrated winding with fractional slots or a distributed winding with integer slots. 4. The modularized three-phase multi-terminal motor as claimed in any one of claims 1-3, wherein the waveforms of the corresponding phases of n three-phase stator modules are consistent, and the corresponding carrier signals of each drive circuit are Symmetrical triangular wave sequence with a carrier period of Ts; the waveforms of each carrier signal are the same, but the phases are different. According to the sequence of modules 1 to n, and according to the torque m times of switching ripples to be eliminated, the phases of each PWM carrier are sequentially shifted by Ts/n/m time, m is any natural number. 5. The modularized three-phase multi-terminal motor according to any one of claims 1-4, wherein the carrier phase-shift pulse width modulation circuit comprises: a triangular wave generator and a phase-shift controller, and the triangular wave generator is used to generate The carrier wave required for modulation; the phase shift controller is used to adjust the initial phase of the triangular wave accordingly. 6. A drive control method based on the modularized three-phase multi-terminal motor according to claim 1, characterized in that, comprising the steps of: After subtracting the reference speed from the measured speed of the motor, the torque reference current is generated after being processed by the speed controller; The torque reference current is divided into n equal parts and used as the current command value of n current controllers, and the measured three-phase current is fed back to the current controller; n current controllers output the voltage duty cycle of n sets of three-phase windings, and compare the voltage duty cycle with the phase-shifted carrier corresponding to each set of three-phase windings to obtain the PWM switch corresponding to each set of three-phase windings Signal; By sending the PWM switching signal to the three-phase inverter and controlling the modular three-phase multi-terminal motor to rotate as required. 7. The drive control method according to claim 6, characterized in that, according to the torque m times switching ripple to be eliminated, according to the order of modules 1 to n, the corresponding carrier signals are phase-shifted by 1/n/m Carrier cycle, m and n are arbitrary natural numbers.