阅读说明：本技术 无电解电容永磁同步电机驱动系统母线电压控制方法 (Bus voltage control method for driving system of permanent magnet synchronous motor without electrolytic capacitor ) 是由 王高林 任泽坤 丁大尉 张国强 徐殿国 于 2021-08-27 设计创作，主要内容包括：一种无电解电容永磁同步电机驱动系统母线电压控制方法,属于电机控制技术领域。本发明针对现有无电解电容永磁同步电机驱动系统在再生制动过程中降速时,由于不能在线调整控制器的控制参数,导致母线侧电压过压的问题。包括：设置电压调节器对母线电压u-(dc)与母线电压限制值u-(dc-max)的母线电压差值进行调整,从而实现对给定q轴电流的调整,以降低电机降速速率；电压调节器通过实时调整的比例系数K-(P)实现对所述母线电压差值的调整；比例系数K-(P)的获得方法包括：计算获得标准q轴电流计算获得比例系数变化量ΔK-(p)的绝对值并确定其正负,将比例系数变化量ΔK-(p)经积分模块积分后与比例系数初值K-(p0)相加,获得比例系数K-(P)。本发明可实现母线侧防过压。(A method for controlling bus voltage of a driving system of a permanent magnet synchronous motor without electrolytic capacitor belongs to the technical field of motor control. The invention aims at the problem that when the speed of the existing electrolytic capacitor-free permanent magnet synchronous motor driving system is reduced in the regenerative braking process, the voltage on the bus side is over-voltage due to the fact that the control parameters of a controller cannot be adjusted on line. The method comprises the following steps: setting the Voltage regulator to the bus Voltage u dc And bus voltage limit u dc‑max The bus voltage difference value is adjusted, thereby realizing the purpose of setting the q-axis current To reduce motor droopA speed rate; proportional coefficient K of voltage regulator adjusted in real time P The adjustment of the bus voltage difference value is realized; coefficient of proportionality K P The obtaining method comprises the following steps: calculating to obtain standard q-axis current Calculating to obtain the proportional coefficient variation delta K p Determining the absolute value of the ratio coefficient, and changing the proportional coefficient by delta K p After being integrated by an integration module, the integral is compared with an initial value K of a proportionality coefficient p0 Adding to obtain a proportionality coefficient K P . The invention can realize the overvoltage prevention of the bus side.)

1. A method for controlling the bus voltage of a driving system of a permanent magnet synchronous motor without electrolytic capacitor is characterized by comprising the following steps,

setting the Voltage regulator to the bus Voltage u_dcAnd bus voltage limit u_dc-maxThe bus voltage difference value is adjusted, thereby realizing the purpose of setting the q-axis currentTo reduce the motor deceleration rate;

the voltage regulationProportional coefficient K of device through real-time adjustment_PThe adjustment of the bus voltage difference value is realized, and the proportionality coefficient K_PThe obtaining method comprises the following steps:

according to the current given q-axis currentAnd collecting the obtained current actual q-axis current i_qCalculating to obtain standard q-axis current

Standard q-axis currentMinus a given q-axis currentMultiplying the absolute value of the difference by the step length n to obtain the change quantity delta K of the proportionality coefficient_pAbsolute value of (d), according to the standard q-axis currentPositive and negative determination of the proportionality coefficient variation Δ K_pPositive and negative, change the proportionality coefficient by delta K_pAfter being integrated by an integration module, the integral is compared with an initial value K of a proportionality coefficient_p0Adding to obtain a proportionality coefficient K_P。

2. The electrolytic capacitor-free permanent magnet synchronous motor drive system bus voltage control method according to claim 1, wherein a given q-axis current is obtainedComprises obtaining a q-axis current set-point of the voltage loop output

The voltage regulator is a voltage PI regulatorThe voltage regulator is used for obtaining a given current-limited current value after current limitation through the current limiting unit of the voltage loop to obtain the adjustment result of the bus voltage difference valueBy using a given current-limited current value through a compensation unitFor the current actual q-axis current i_qCompensating to obtain the given value of q-axis current output by the voltage loop

3. The electrolytic capacitor-free permanent magnet synchronous motor drive system bus voltage control method according to claim 2, wherein a given q-axis current is obtainedFurther comprises obtaining a given q-axis current output by the speed loop

Will set the rotation speedSubtracting the observed speedThe difference value is regulated by a rotating speed regulator and then limited by a rotating speed ring current limiting unit to obtain the given q-axis current output by a rotating speed ring

4. The electrolytic-less capacitor of claim 3A bus voltage control method of a permanent magnet synchronous motor driving system is characterized in that given q-axis current output by a rotating speed ringQ-axis current setpoint output by sum voltage loopAdding to obtain a given q-axis current

5. The electrolytic capacitor-less permanent magnet synchronous motor drive system bus voltage control method according to claim 4,

the observed rotation speedBy a rotational speed position observer according to a given alpha axis voltage u on a two-phase stationary coordinate system_α ^*Given beta axis voltage u on a two phase stationary frame_β ^*Alpha axis current i on a two phase stationary frame_αAnd beta axis current i on two-phase stationary coordinate system_βAnd (6) calculating.

6. The electrolytic capacitor-less permanent magnet synchronous motor drive system bus voltage control method according to claim 5,

standard q-axis currentThe calculating method comprises the following steps:

wherein n is_pIs the number of pole pairs, psi, of the rotor_fFor the rotor to be magneticChain, omega_m0As steady value of the rotational speed, K_iIs an integral coefficient of the voltage regulator, u_dc0Is a steady state value of the bus voltage, C_dcIs the capacitance value of the bus capacitor.

7. The electrolytic capacitor-free permanent magnet synchronous motor drive system bus voltage control method according to claim 6, wherein the actual q-axis current i_qThe obtaining process comprises the following steps:

a-phase current i output to a three-phase inverter_aPhase i of b-phase current_bAnd c-phase current i_cClark conversion and Park conversion are carried out in sequence to obtain actual q-axis current i_q。

8. The electrolytic capacitor-free permanent magnet synchronous motor drive system bus voltage control method according to claim 7, wherein the compensation unit adopts a given current-limited current valueFor the current actual q-axis current i_qThe method for compensating comprises the following steps:

when the actual q-axis current i_qWhen the current value is more than 0, the current value after current limiting is givenCompensating the current actual q-axis current iq to enable the output q-axis current to be given valueIs 0;

when the actual q-axis current i_qWhen the current value is less than or equal to 0, giving the current value after current limitingFor the current actual q-axis current i_qCompensating to output a given value of q-axis currentEqual to a given current-limited current value

9. The electrolytic capacitor-free permanent magnet synchronous motor drive system bus voltage control method according to claim 8, wherein the observed rotation speedThe value range of (A) is 0.2-0.9 times of rated rotation speed.

10. The electrolytic capacitor-free permanent magnet synchronous motor drive system bus voltage control method according to claim 9, wherein the adjustment process of the bus voltage difference by the voltage regulator comprises: proportionality coefficient K to be adjusted in real time_PAnd assigning a PI parameter to the voltage regulator, and forming closed-loop control on the bus voltage difference by adopting the updated voltage regulator.

Technical Field

The invention relates to a bus voltage control method of a driving system of a permanent magnet synchronous motor without electrolytic capacitors, and belongs to the technical field of motor control.

Background

The three-phase input electrolytic capacitor permanent magnet synchronous motor realizes the smoothness and the stability of the bus voltage through the large-capacity electrolytic capacitor, and the service life of the electrolytic capacitor is short, so that the service life of a driving system is limited. The use of thin film capacitors by the motor system not only extends the life of the drive system, but also enables lower Total Harmonic Distortion (THD) in the grid current. However, the use of the thin film capacitor causes a reduction in the capacitance value of the bus capacitor, which makes the regenerative braking process of the electrolytic capacitor-less driving system face problems such as bus voltage overvoltage.

At present, there are hardware and software control solutions for the condition of bus voltage overvoltage for the non-electrolytic capacitor driving system respectively. The hardware scheme is that an auxiliary brake resistor controlled by the switch device is connected in parallel on the bus side, and the additional hardware mode not only needs to increase the capacity of a driving system, but also increases the cost of the system. The software control scheme is to reduce the motor deceleration rate and increase the motor losses by controlling a given current in the regenerative braking mode, including controlling the q-axis current by the voltage controller to reduce the motor deceleration rate and controlling the d-axis current by the loss controller to maximize the motor losses. However, the optimal control parameters of the controller have different values under different working conditions, and the inappropriate value of the control parameters can result in poor dynamic performance of the system.

In the existing driving system of the permanent magnet synchronous motor without the electrolytic capacitor, when the bus side thin film capacitor replaces the electrolytic capacitor with a large capacitance value and the speed and load are reduced in the regenerative braking process of the motor, the problem of overvoltage of the bus side voltage is easily caused because the control parameters of the controller cannot be timely and effectively adjusted.

Disclosure of Invention

The invention provides a bus voltage control method of a permanent magnet synchronous motor driving system without electrolytic capacitor, aiming at the problem of overvoltage of bus side voltage caused by incapability of adjusting control parameters of a controller on line when the existing permanent magnet synchronous motor driving system without electrolytic capacitor is decelerated in the regenerative braking process.

The invention relates to a method for controlling the bus voltage of a driving system of a permanent magnet synchronous motor without electrolytic capacitor, which comprises the following steps,

setting the Voltage regulator to the bus Voltage u_dcAnd bus voltage limit u_dc-maxThe bus voltage difference value is adjusted, thereby realizing the purpose of setting the q-axis currentTo reduce the motor deceleration rate;

the voltage regulator has a real-time adjusted proportionality coefficient K_PThe adjustment of the bus voltage difference value is realized, and the proportionality coefficient K_PThe obtaining method comprises the following steps:

according to the current given q-axis currentAnd collecting the obtained current actual q-axis current i_qCalculating to obtain standard q-axis current

Standard q-axis currentMinus a given q-axis currentIs multiplied by stepThe length n is used for obtaining the proportional coefficient variation delta K_pAbsolute value of (d), according to the standard q-axis currentPositive and negative determination of the proportionality coefficient variation Δ K_pPositive and negative, change the proportionality coefficient by delta K_pAfter being integrated by an integration module, the integral is compared with an initial value K of a proportionality coefficient_p0Adding to obtain a proportionality coefficient K_P。

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the given q-axis current is obtainedComprises obtaining a q-axis current set-point of the voltage loop output

The voltage regulator is a voltage PI regulator, and the voltage regulator obtains a given current-limited current value after the regulation result of the bus voltage difference value is limited by the voltage ring current limiting unitBy using a given current-limited current value through a compensation unitFor the current actual q-axis current i_qCompensating to obtain the given value of q-axis current output by the voltage loop

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the given q-axis current is obtainedFurther comprises obtaining a given q-axis current output by the speed loop

Will set the rotation speedSubtracting the observed speedThe difference value is regulated by a rotating speed regulator and then limited by a rotating speed ring current limiting unit to obtain the given q-axis current output by a rotating speed ring

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the given q-axis current is output by a rotating speed ringQ-axis current setpoint output by sum voltage loopAdding to obtain a given q-axis current

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the observation rotating speedBy a rotational speed position observer according to a given alpha axis voltage u on a two-phase stationary coordinate system_α ^*Given beta axis voltage u on a two phase stationary frame_β ^*Alpha axis current i on a two phase stationary frame_αAnd beta axis current i on two-phase stationary coordinate system_βAnd (6) calculating.

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the standard q-axis currentThe calculating method comprises the following steps:

wherein n is_pIs the number of pole pairs, psi, of the rotor_fFor rotor flux linkage, omega_m0As steady value of the rotational speed, K_iIs an integral coefficient of the voltage regulator, u_dc0Is a steady state value of the bus voltage, C_dcIs the capacitance value of the bus capacitor.

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the actual q-axis current i_qThe obtaining process comprises the following steps:

a-phase current i output to a three-phase inverter_aPhase i of b-phase current_bAnd c-phase current i_cClark conversion and Park conversion are carried out in sequence to obtain actual q-axis current i_q。

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the compensation unit adopts a given current-limited current valueFor the current actual q-axis current i_qThe method for compensating comprises the following steps:

when the actual q-axis current i_qWhen the current value is more than 0, the current value after current limiting is givenCompensating the current actual q-axis current iq to enable the output q-axis current to be given valueIs 0;

when the actual q-axis current i_qWhen the current value is less than or equal to 0, giving the current value after current limitingFor the current actual qCompensating the shaft current iq to enable the output q-shaft current to be given valueEqual to a given current-limited current value

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the rotating speed is observedThe value range of (A) is 0.2-0.9 times of rated rotation speed.

According to the method for controlling the bus voltage of the driving system of the electrolytic capacitor-free permanent magnet synchronous motor, the process of adjusting the bus voltage difference by the voltage regulator comprises the following steps: proportionality coefficient K to be adjusted in real time_PAnd assigning a PI parameter to the voltage regulator, and forming closed-loop control on the bus voltage difference by adopting the updated voltage regulator.

The invention has the beneficial effects that:

the invention changes the proportional coefficient variable delta K through real time_pTo adjust the proportionality coefficient K_PThe motor is an optimal value, the purpose of preventing overvoltage can be effectively achieved, the dynamic performance of a driving system is improved, and the optimal performance of the motor is ensured. The problems of high cost and low power density of a driving system caused by the parallel connection of auxiliary brake resistors in a hardware scheme are effectively solved.

The method of the invention realizes the real-time calculation of the optimal parameters of the controller in the regenerative braking operation of the driving system, thereby realizing the purpose of overvoltage prevention at the bus side and higher dynamic performance of the driving system.

Drawings

FIG. 1 is a block diagram of the control system of the method for controlling the bus voltage of the driving system of the permanent magnet synchronous motor without the electrolytic capacitor according to the present invention; in the figure i_q-minFor the minimum value of the output current of the speed regulator, i_q-maxIs the maximum value of the output current of the speed regulator,for a given q-axis current, i, on a two-phase rotating coordinate_dIs the actual d-axis current, i, on a two-phase rotating coordinate_qIs the actual q-axis current on the two-phase rotating coordinate,for observation angle, AC is the AC source;

FIG. 2 is a waveform of various variables when the motor speed is reduced from 75Hz to 0Hz and no load is applied in the specific embodiment; in the figure, n is the rotating speed;

FIG. 3 is a waveform diagram of various variables during sudden unloading of a 30N m load during sudden increase of the motor speed from 5Hz to 75Hz in the specific embodiment.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.

The invention is further described with reference to the following drawings and specific examples, which are not intended to be limiting.

First embodiment, referring to fig. 1, the present invention provides a method for controlling bus voltage of a driving system of a permanent magnet synchronous motor without electrolytic capacitor, including,

setting the Voltage regulator to the bus Voltage u_dcAnd bus voltage limit u_dc-maxThe bus voltage difference value is adjusted, thereby realizing the purpose of setting the q-axis currentTo reduce the motor deceleration rate;

the voltage regulator has a real-time adjusted proportionality coefficient K_PThe adjustment of the bus voltage difference value is realized, and the proportionality coefficient K_PThe obtaining method comprises the following steps:

according to the current given q-axis currentAnd collecting the obtained current actual q-axis current i_qCalculating to obtain standard q-axis current

Standard q-axis currentMinus a given q-axis currentMultiplying the absolute value of the difference by the step length n to obtain the change quantity delta K of the proportionality coefficient_pAbsolute value of (d), according to the standard q-axis currentPositive and negative determination of the proportionality coefficient variation Δ K_pPositive and negative, change the proportionality coefficient by delta K_pAfter being integrated by an integration module, the integral is compared with an initial value K of a proportionality coefficient_p0Adding to obtain a proportionality coefficient K_P。

In the present embodiment, the standard q-axis currentMinus a given q-axis currentMultiplying the absolute value of the difference by the step length n to obtain the change quantity delta K of the proportionality coefficient_pAbsolute value of (1 | Δ K)_pAccording to standard q-axis currentPositive and negative of (1) determining Δ K_pPositive and negative, real-time calculation ofObtaining the proportional coefficient variation delta K_p。

The bus voltage u_dcThe output voltage of the diode rectifier bridge of fig. 1.

The embodiment changes the change amount Δ K of the proportionality coefficient through real time_pAdjustable proportionality coefficient K_PIs an optimal value, so that the motor performance can be determined to be optimal.

Further, as shown in connection with FIG. 1, a given q-axis current is obtainedComprises obtaining a q-axis current set-point of the voltage loop output

The voltage regulator is a voltage PI regulator, and the voltage regulator obtains a given current-limited current value after the regulation result of the bus voltage difference value is limited by the voltage ring current limiting unitBy using a given current-limited current value through a compensation unitFor the current actual q-axis current i_qCompensating to obtain the given value of q-axis current output by the voltage loop

Current actual q-axis current i_qAnd setting the current value after current limitingAfter the q-axis current is input to the compensation unit together, the given value of the q-axis current output by the voltage loop is obtained

Still further, as shown in connection with FIG. 1, a given q-axis current is obtainedFurther comprises obtaining a given q-axis current output by the speed loop

Will set the rotation speedSubtracting the observed speedThe difference value is regulated by a rotating speed regulator and then limited by a rotating speed ring current limiting unit to obtain the given q-axis current output by a rotating speed ring

Is a partial q-axis current not less than 0, and the matched bus voltage exceeds the bus voltage limit value u_dc-maxWhen is less than 0The motor deceleration rate can be reduced, the purpose of preventing overvoltage is effectively realized, and the dynamic performance of a driving system is improved.

Still further, as shown in connection with FIG. 1, a given q-axis current output by the speed loopQ-axis current setpoint output by sum voltage loopAdding to obtain a given q-axis currentObtained given q-axis currentAnd the overvoltage prevention control can be realized.

Still further, as shown in connection with FIG. 1, the observed rotational speedBy a rotational speed position observer according to a given alpha axis voltage u on a two-phase stationary coordinate system_α ^*Given beta axis voltage u on a two phase stationary frame_β ^*Alpha axis current i on a two phase stationary frame_αAnd beta axis current i on two-phase stationary coordinate system_βAnd (6) calculating.

Still further, as shown in connection with FIG. 1, the standard q-axis currentThe calculating method comprises the following steps:

wherein n is_pIs the number of pole pairs, psi, of the rotor_fFor rotor flux linkage, omega_m0As steady value of the rotational speed, K_iIs an integral coefficient of the voltage regulator, u_dc0Is a steady state value of the bus voltage, C_dcIs the capacitance value of the bus capacitor.

Still further, as shown in connection with FIG. 1, the actual q-axis current i_qThe obtaining process comprises the following steps:

a-phase current i output to a three-phase inverter_aPhase i of b-phase current_bAnd c-phase current i_cClark conversion and Park conversion are carried out in sequence to obtain actual q-axis current i_q。

Still further, as shown in fig. 1, the compensation unit adopts a given current-limited current valueFor the current actual q-axis current i_qThe method for compensating comprises the following steps:

when the actual q-axis current i_qWhen the current value is more than 0, the current value after current limiting is givenCompensating the current actual q-axis current iq to enable the output q-axis current to be given valueIs 0;

when the actual q-axis current i_qWhen the current value is less than or equal to 0, giving the current value after current limitingCompensating the current actual q-axis current iq to enable the output q-axis current to be given valueEqual to a given current-limited current value

Still further, as shown in FIG. 1, the rotational speed is observedThe value range of (A) is 0.2-0.9 times of rated rotation speed.

Still further, the voltage regulator adjusts the proportionality coefficient K through real time_PThe bus voltage difference value adjusting process comprises the following steps: proportionality coefficient K to be adjusted in real time_PAnd assigning a PI parameter to the voltage regulator, and forming closed-loop control on the bus voltage difference by adopting the updated voltage regulator.

In the method of the present invention, a q-axis current is givenWith actual q-axis current i_qThe difference is input to a current regulator to give d-axis currentWith fruitInter d-axis current i_dThe difference value of the two phase d-axis voltage is input into a current regulator, and a given d-axis voltage on a two-phase rotating coordinate is obtained through calculationAnd a given q-axis voltage on a two-phase rotation coordinateThen, a given alpha axis voltage u on the two-phase static coordinate system is obtained through Park inverse transformation_α ^*And a given beta-axis voltage u on a two-phase stationary frame_β ^*；u_α ^*And u_β ^*And the PWM modulation is carried out to be used as a control signal of the three-phase inverter.

FIG. 1 includes a position sensorless vector control section, K_pA parameter setting section and a voltage controller section; the voltage controller part is shown as a dotted line frame in fig. 1 and comprises a voltage regulator, a voltage loop current limiting unit and a compensation unit; the vector control part without the position sensor comprises an inner ring, an outer ring, a speed regulator, a current regulator and a current regulator, wherein the inner ring is a current ring, the outer ring is a speed ring, the difference between a reference value and a feedback value of the rotating speed is regulated by the speed regulator, the difference between a reference value and a feedback value of the direct-axis current is regulated by the current regulator, and the difference between a reference value and a feedback value of the quadrature-axis current is regulated by the current regulator. The angle and position of the motor are obtained by a position, speed observer. And the three-phase current of the motor stator is converted by Clark and Park coordinates to obtain d-axis and q-axis currents under a two-phase rotating coordinate system. And the SVPWM is adopted to control the three-phase inverter, and finally the permanent magnet synchronous motor control is realized.

The specific embodiment is as follows:

the validity of the method is verified as follows:

the effectiveness of the anti-overvoltage control method provided by the invention is verified on a driving system platform of the electrolytic capacitor-free permanent magnet synchronous motor. The parameters of the experimental platform are set as follows: the power grid voltage is 380V, the power grid frequency is 50Hz, the direct current bus capacitance is film capacitance, the capacitance value is 30 muF, the direct axis inductance is 7.5mH, the alternating axis inductance is 17.2mH, the rotor flux linkage is 0.5Wb, the number of rotor pole pairs is 3, the rated power is 11kW, the rated rotation speed is 1500r/min, and the stator resistance is 0.275 omega.

All control algorithms in the experiment are completed in the DSP STM32F 28075. The update frequency of the switch and the current and voltage sampling values is set to be 8 kHz. Bus voltage limit u_dc-maxSet to 618V.

As shown in fig. 2, when the motor speed command is suddenly decreased from 75Hz to 0Hz without applying a load, the dc-side bus voltage is controlled to be about 618V.

As shown in fig. 3, when the load of 30N · m is suddenly unloaded during the sudden increase of the motor speed command from 5Hz to 75Hz, the dc-side bus voltage is controlled to be around 618V.

Therefore, the method provided by the invention has the advantages that the bus voltage can be effectively controlled in the regenerative braking process of the motor, and the dynamic performance of the motor is ensured.

Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that features described in different dependent claims and herein may be combined in ways different from those described in the original claims. It is also to be understood that features described in connection with individual embodiments may be used in other described embodiments.