阅读说明：本技术 一种基于混合储能单元的无刷直流电机系统控制方法 (Brushless direct current motor system control method based on hybrid energy storage unit ) 是由 曹彦飞 陆海天 宋鹏 李新旻 史婷娜 于 2019-10-08 设计创作，主要内容包括：本发明公开了一种基于混合储能单元的无刷直流电机系统控制方法。构建混合储能单元,混合储能单元输出接至三相逆变器输入,三相逆变器输出接无刷直流电机三相绕组；处于制动,根据混合储能单元和三相逆变器构建两种制动矢量,通过两种矢量作用实现制动转矩控制时将制动能量回馈至超级电容；处于电动,根据混合储能单元和三相逆变器构建四种电动矢量,电机加速通过不同矢量作用实现蓄电池和超级电容的功率分担控制,电机恒速通过不同矢量作用实现换相阶段的转矩波动抑制。本发明在无刷直流电机制动减速运行、加速运行及恒速运行模式下均获得良好的控制性能,并且使用超级电容作为能量缓冲装置可以很好地缓解频繁充放电对蓄电池使用寿命的影响。(The invention discloses a brushless direct current motor system control method based on a hybrid energy storage unit. Constructing a hybrid energy storage unit, wherein the output of the hybrid energy storage unit is connected to the input of a three-phase inverter, and the output of the three-phase inverter is connected with a three-phase winding of the brushless direct current motor; when the hybrid energy storage unit is braked, two braking vectors are constructed according to the hybrid energy storage unit and the three-phase inverter, and braking energy is fed back to the super capacitor when braking torque control is realized through the action of the two vectors; the hybrid energy storage system is in an electric state, four electric vectors are constructed according to the hybrid energy storage unit and the three-phase inverter, the motor is accelerated to share and control the power of the storage battery and the super capacitor through different vector effects, and the motor is constant in speed to suppress torque fluctuation in a phase change stage through different vector effects. The invention obtains good control performance in braking, decelerating, accelerating and constant speed running modes of the brushless direct current motor, and the super capacitor is used as an energy buffer device to well relieve the influence of frequent charging and discharging on the service life of the storage battery.)

1. A brushless direct current motor system control method based on a hybrid energy storage unit is characterized in that: the method comprises the following steps:

1) the hybrid energy storage unit is designed and constructed by adopting a storage battery, an electrolytic capacitor C, a bidirectional power switch tube, a first power MOS tube, a second power MOS tube and a super capacitor SC, the first power MOS tube and the second power MOS tube are connected in series and then are connected with the electrolytic capacitor C in parallel at two ends of the storage battery, the drain electrode of the first power MOS tube is connected to the anode of the storage battery, and the bidirectional power switch tube and the super capacitor SC are connected in series and then are connected with two ends of the first power MOS tube in parallel; a negative end serving as the output of the hybrid energy storage unit is led out between the second power MOS tube and the negative electrode of the storage battery, a positive end serving as the output of the hybrid energy storage unit is led out between the bidirectional power switch tube and the positive electrode of the super capacitor SC, two ends of the output of the hybrid energy storage unit are connected to two input ends of a three-phase inverter, and the output end of the three-phase inverter is connected with a three-phase winding of the brushless direct current motor;

2) when the motor is in the braking state,

two braking vectors are constructed according to the action of the switching states of the power tubes in the hybrid energy storage unit and the three-phase inverter on the input line voltage of the brushless direct current motor, and the braking energy is fed back to the super capacitor SC while the braking torque control is realized through the combined action of the two braking vectors;

3) when the motor is in the electric state,

four electric vectors are constructed according to the action of the switching states of the power tubes in the hybrid energy storage unit and the three-phase inverter on the input line voltage of the motor:

when the motor is in electric acceleration operation, the sharing control of the power of the storage battery and the super capacitor is realized through the combined action of different electric vectors,

when the motor is in electric constant speed operation, the torque fluctuation suppression in the phase change stage is realized through the combined action of different electric vectors.

2. The control method of the hybrid energy storage unit-based brushless direct current motor system according to claim 1, wherein: the step 2) is specifically as follows:

2.1) two types of vectors are constructed: when a bidirectional power switch tube in the hybrid energy storage unit is conducted, a lower bridge arm power tube in a positive conducting phase of the brushless direct current motor in the three-phase inverter is conducted with an upper bridge arm power tube in a negative conducting phase of the brushless direct current motor, and the hybrid energy storage unit and the other power tubes in the three-phase inverter are all turned off, a formed voltage vector is used as a first braking vector V_z,b1(ii) a When the second power MOS tube in the hybrid energy storage unit is switched on and the hybrid energy storage unit and the rest power tubes in the three-phase inverter are switched off, the formed voltage vector is used as a braking second vector V_z,c0；

2.2) the combined action of the two vectors satisfies the following relationship:

d_z,b1u_b+(d_z,b1-1)u_sc＝2R_sI-2E

wherein d is_z,b1For braking a first vector V_z,b1Duty cycle of action u_bIs the voltage of the storage battery, and the voltage of the storage battery is equal to the rated voltage u of the brushless direct current motor_N，u_scIs the super capacitor voltage, R_sAnd E are respectively brushless direct currentThe phase resistance and the opposite potential of the motor, and I is the phase current amplitude of the brushless direct current motor.

3. The control method of the hybrid energy storage unit-based brushless direct current motor system according to claim 1, wherein: the step 3) is specifically as follows:

3.1) construction of four types of vectors are:

when a bidirectional power switch tube in the hybrid energy storage unit is conducted, an upper bridge arm power tube in a positive conducting phase of the brushless direct current motor and a lower bridge arm power tube in a negative conducting phase of the brushless direct current motor in the three-phase inverter are conducted, and the other power tubes are turned off, a formed voltage vector is used as an electric first vector V_m,b1；

When a second power MOS tube in the hybrid energy storage unit is conducted, an upper bridge arm power tube in a positive conducting phase of the brushless direct current motor and a lower bridge arm power tube in a negative conducting phase of the brushless direct current motor in the three-phase inverter are conducted, and the hybrid energy storage unit and the other power tubes in the three-phase inverter are all turned off, a formed voltage vector is used as an electric second vector V_m,c1；

When the first power MOS tube in the hybrid energy storage unit is conducted, the upper bridge arm power tube in the positive conducting phase of the brushless direct current motor in the three-phase inverter is conducted with the lower bridge arm power tube in the negative conducting phase of the brushless direct current motor, and the other power tubes in the hybrid energy storage unit and the three-phase inverter are all turned off, the formed voltage vector is used as an electric third vector V_m,s1；

When only the upper bridge arm power tube on the positive conducting phase of the brushless direct current motor in the three-phase inverter is conducted or only the lower bridge arm power tube on the negative conducting phase of the brushless direct current motor in the three-phase inverter is conducted, and the rest power tubes in the three-phase inverter are turned off, no matter the on-off state of the power tubes in the hybrid energy storage unit, the formed voltage vector is used as an electric fourth vector V_m,0；

3.2) when the motor runs in an accelerated mode, the combined action of different vectors meets the following relation:

when the brushless DC motor is in the forward conduction phaseAnd the line voltage u between the negative conducting phases_pn≤d_maxu_bWhile, using a motorized first vector V_m,b1And electromotive fourth vector V_m,0Coact and satisfy:

u_pn＝d_m,b1u_b＝2E+2R_sI

wherein d is_maxA constraint duty cycle for limiting the magnitude of the output current of the battery during acceleration, and d_max＝I_bat,max/I，I_bat,maxIs the maximum output current of the battery, u_bIs the voltage of the storage battery, and the voltage of the storage battery is equal to the rated voltage u of the brushless direct current motor_N，d_m,b1Is a motor-driven first vector V_m,b1Duty ratio of R_sE is the phase resistance and the opposite potential of the brushless DC motor respectively, and I is the phase current amplitude of the brushless DC motor;

when u is_pn>d_maxu_bWhile, using a motorized first vector V_m,b1And electric third vector V_m,s1And electromotive fourth vector V_m,0Coact and satisfy:

u_pn＝d_maxu_b+d_m,s1u_sc＝2E+2R_sI

wherein d is_m,s1As a third electric vector V_m,s1Duty ratio of u_scIs the super capacitor voltage;

when u is_pn>d_max(u_b+u_sc) While, using a motorized third vector V_m,s1Electric second vector V_m,c1And electromotive fourth vector V_m,0Coact and satisfy:

u_pn＝d_maxu_b+(d_max+d_m,c1)u_sc

wherein d is_m,c1Is a second vector V of electric motion_m,c1Duty cycle of (d);

3.3) when the motor operates at constant speed, the electric third vector V is adopted in the phase change stage_m,s1And electromotive fourth vector V_m,0Coact and satisfy:

2d_m,s1(u_b+u_sc)＝4E+3R_sI+u_b+u_sc。

4. the control method of the hybrid energy storage unit-based brushless direct current motor system according to claim 1, wherein:

the positive end of the output of the hybrid energy storage unit is connected to the positive end of the direct-current bus of the three-phase inverter, and the negative end of the output of the hybrid energy storage unit is connected to the negative end of the direct-current bus of the three-phase inverter.

5. The control method of the hybrid energy storage unit-based brushless direct current motor system according to claim 1, wherein:

the bidirectional power switch tube is formed by connecting two MOS tubes in series in the reverse direction.

6. The control method of the hybrid energy storage unit-based brushless direct current motor system according to claim 1, wherein:

the three-phase inverter comprises three MOS tube groups connected in parallel, each MOS tube group is composed of two MOS tubes connected in series in the same direction, and one phase connected to the brushless direct current motor is led out between the two MOS tubes of each MOS tube group.

Technical Field

The invention relates to a brushless direct current motor system control method, in particular to a brushless direct current motor system control method based on a hybrid energy storage unit.

Background

The brushless direct current motor is widely applied to the fields of electric automobiles, industrial control, aerospace and the like due to the advantages of high power density, simple structure and the like. In many applications of brushless dc motors, a high energy density battery is often used as a main power supply, but the battery has disadvantages such as limited power density and a small number of charge and discharge cycles. For example, in the application of an electric vehicle, frequent acceleration and deceleration of the motor can cause the battery to be charged and discharged with high power, thereby having adverse effect on the service life of the storage battery.

In recent years, scholars at home and abroad propose a method for applying a super capacitor/storage battery hybrid energy storage unit, compared with a storage battery, the super capacitor has higher power density, and frequent charging and discharging hardly influences the service life of the storage battery. Therefore, the super capacitor/storage battery hybrid energy storage unit has the following advantages: in the braking process, the motor can convert mechanical energy into electric energy to feed back to the super capacitor, so that the energy utilization rate is improved, and the adverse effect on the storage battery caused by frequent charging is avoided; in the occasions where the motor needs to output high power in the acceleration process and the like, the super capacitor can be used for assisting the storage battery to supply power to the motor, and the problem of short service life of the storage battery caused by overhigh output power is effectively solved.

E.chemali and m.penindl et al introduced the current development of super capacitors and storage batteries and explained the structure of a common hybrid energy storage unit (IEEE Journal of ignition and Selected capacitors in power electron, vol.4, No.3, pp.1117-1134,2016, 9 months). The passive structure directly connects the super capacitor and the storage battery to the load in parallel, and is a relatively simple and reliable structure, the output power of the super capacitor and the output power of the storage battery are respectively determined by the internal resistance of the super capacitor and the internal resistance of the storage battery, but the voltage utilization range of the super capacitor is limited due to the clamping effect of the voltage of the storage battery. In order to increase the voltage utilization range of the super capacitor, a common method is to connect the super capacitor to a load through a bidirectional DC-DC converter, and directly connect the storage battery to the load, so as to form a semi-active hybrid energy storage unit. There are also active configurations proposed in which the battery and the super capacitor are connected to the load by two DC-DC converters, respectively. The hybrid energy storage unit with the added DC-DC converter can effectively improve the voltage utilization range of the super capacitor, and the size of the system needs to be balanced in circuit design because the hybrid energy storage unit needs an inductor to realize peak power transmission.

In a driving system using a brushless direct current motor as a power element, since the torque performance of the motor is a key index for measuring the performance of the driving system, it is significant to design a hybrid energy storage unit while considering the torque performance of the motor, and currently, related studies have been conducted by researchers (IEEE trans. veh.technol., vol.66, No.5, pp.3724-3738,2017, 5 months; IEEE trans. veh.technol., vol.60, No.1, pp.89-97,2011, 1 month). However, in the existing method, the problem of commutation torque fluctuation of the brushless direct current motor is considered while designing the hybrid energy storage unit, and the commutation torque fluctuation existing in the operation process of the brushless direct current motor can cause larger noise and vibration, so that the operation stability of the motor is reduced.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, designs the super capacitor/storage battery hybrid energy storage unit with a simple structure, and provides a brushless direct current motor operation control strategy based on the hybrid energy storage unit, so that the phase change torque fluctuation is effectively inhibited, and the brushless direct current motor obtains good control performance in braking, decelerating, accelerating and constant-speed operation modes.

In order to achieve the above purpose, as shown in fig. 1, the present invention adopts the following technical solutions:

1) as shown in fig. 1, the system includes a hybrid energy storage unit, an inverter and a brushless dc motor, the hybrid energy storage unit is designed and constructed by a storage battery, an electrolytic capacitor C, a bidirectional power switching tube, a first power MOS tube, a second power MOS tube and a super capacitor SC, the first power MOS tube and the second power MOS tube are connected in series and then connected in parallel to two ends of the storage battery together with the electrolytic capacitor C, a drain electrode of the first power MOS tube is connected to an anode of the storage battery, a source electrode of the second power MOS tube is connected to a cathode of the storage battery, the bidirectional power switching tube and the super capacitor SC are connected in series and then connected in parallel to two ends of the first power MOS tube, and a source electrode of the first power MOS tube is connected to a cathode of the super; a negative end which is used as the output of the hybrid energy storage unit is led out between the second power MOS tube and the negative electrode of the storage battery, a positive end which is used as the output of the hybrid energy storage unit is led out between the bidirectional power switch tube and the positive electrode of the super capacitor SC, the negative end which is output by the hybrid energy storage unit and the positive end which is output by the hybrid energy storage unit form two ends of the output of the hybrid energy storage unit, the two ends of the output of the hybrid energy storage unit are connected to two input ends of a three-phase inverter (VSI), and the output end of the three-phase inverter is connected with a three-phase winding of a;

Drawings

Fig. 1 is a block diagram of a proposed hybrid energy storage unit-based brushless dc motor system control method;

FIG. 2 is a brushless DC motor system powered by a hybrid energy storage unit;

fig. 3a is a schematic diagram of an output mode 1 state of the hybrid energy storage unit;

fig. 3b is a schematic diagram of the output mode 2 state of the hybrid energy storage unit;

fig. 3c is a schematic diagram of the output mode 3 state of the hybrid energy storage unit;

FIG. 4 is a waveform diagram of an ideal counter potential of a brushless DC motor;

FIG. 5a is a vector V_z,c0Schematic diagram of equivalent circuit state under action;

FIG. 5b is a vector V_z,b1Schematic diagram of equivalent circuit state under action;

FIG. 6a is a vector V_m,b1Schematic diagram of equivalent circuit state under action;

FIG. 6b is a vector V_m,c1Schematic diagram of equivalent circuit state under action;

FIG. 6c is a vector V_m,s1Schematic diagram of equivalent circuit state under action;

FIG. 6d is a vector V_m,0Schematic diagram of equivalent circuit state under action;

FIG. 7a shows a vector V at the time of phase inversion of the positive on-phase current_m,s1An equivalent circuit schematic under action;

FIG. 7b shows a vector V for the phase change of the positive on-phase current_m,0Schematic diagram of equivalent circuit under action.

in specific implementation, the storage battery is connected with the electrolytic capacitor in parallel, the positive electrode of the storage battery is connected with the drain electrode of the first power MOS tube, the negative electrode of the storage battery is connected with the source electrode of the second power MOS tube, the source electrode of the first power MOS tube and the drain electrode of the second power MOS tube are connected to the negative electrode of the super capacitor, one end of the bidirectional power switch tube is connected with the positive electrode of the storage battery, and the other end of the bidirectional power switch tube is connected with the positive electrode of the super capacitor. The positive end of the output of the hybrid energy storage unit is connected to the positive end of the direct-current bus of the three-phase inverter, and the negative end of the output of the hybrid energy storage unit is connected to the negative end of the direct-current bus of the three-phase inverter.

The bidirectional power switch tube is formed by connecting two MOS tubes in series in the reverse direction.

The three-phase inverter comprises three MOS tube groups connected in parallel, each MOS tube group is composed of two MOS tubes connected in series in the same direction, one phase connected to the brushless DC motor is led out between the two MOS tubes of each MOS tube group, and the first MOS tube group is composed of MOS tubes S_aHAnd MOS transistor S_aLThe MOS tubes of the second group are connected in series in the same direction and composed of MOS tubes S_bHAnd MOS transistor S_bLThe MOS tubes of the third group are connected in series in the same direction and composed of MOS tubes S_cHAnd MOS transistor S_cLAre connected in series in the same direction.

2) When the motor is in a braking state, two braking vectors are constructed according to the action of the switching states of the hybrid energy storage unit and the power tube in the three-phase inverter on the input line voltage of the brushless direct current motor, and the braking energy is fed back to the super capacitor SC while the braking torque control is realized through the combined action of the two braking vectors;

3) when the motor is in an electric state:

four electric vectors are constructed according to the action of the switching states of the power tubes in the hybrid energy storage unit and the three-phase inverter on the input line voltage of the motor:

when the motor is in electric acceleration operation, the sharing control of the power of the storage battery and the super capacitor is realized through the combined action of different electric vectors,

when the motor is in electric constant speed operation, the torque fluctuation suppression in the phase change stage is realized through the combined action of different electric vectors.

The step 2) is specifically as follows:

2.1) two types of vectors are constructed:

when a bidirectional power switch tube in the hybrid energy storage unit is conducted, a lower bridge arm power tube in a positive conducting phase of the brushless direct current motor in the three-phase inverter is conducted with an upper bridge arm power tube in a negative conducting phase of the brushless direct current motor, and the hybrid energy storage unit and the other power tubes in the three-phase inverter are all turned off, a formed voltage vector is used as a first braking vector V_z,b1；

When the brushless direct current motor adopts a pairwise conduction square wave current driving mode, a current excitation winding in phase with the positive counter potential is defined as a positive conduction phase, and a current excitation winding in phase opposite to the positive counter potential is defined as a negative conduction phase; the upper bridge arm power tube is connected with the output positive end of the hybrid energy storage unit, and the lower bridge arm power tube is connected with the output negative end of the hybrid energy storage unit.

When the second power MOS tube in the hybrid energy storage unit is switched on and the hybrid energy storage unit and the rest power tubes in the three-phase inverter are switched off, the formed voltage vector is used as a braking second vector V_z,c0；

2.2) the combined action of the two vectors satisfies the following relationship:

d_z,b1u_b+(d_z,b1-1)u_sc＝2R_sI-2E

wherein d is_z,b1For braking a first vector V_z,b1Duty cycle of action u_bIs the voltage of the storage battery, and the voltage of the storage battery is equal to the rated voltage u of the brushless direct current motor_N，u_scIs the super capacitor voltage, R_sAnd E is the phase resistance and the opposite potential of the brushless DC motor respectively, and I is the phase current amplitude of the brushless DC motor. Due to braking of the second vector V_z,c0The duty ratio of (d) is reduced by 0 in the formula, and thus is not shown in the formula, as follows.

The step 3) is specifically as follows:

3.1) construction of four types of vectors are:

when a bidirectional power switch tube in the hybrid energy storage unit is conducted, an upper bridge arm power tube in a positive conducting phase of the brushless direct current motor and a lower bridge arm power tube in a negative conducting phase of the brushless direct current motor in the three-phase inverter are conducted, and the other power tubes are turned off, a formed voltage vector is used as an electric first vector V_m,b1；

When a second power MOS tube in the hybrid energy storage unit is conducted, an upper bridge arm power tube in a positive conducting phase of the brushless direct current motor and a lower bridge arm power tube in a negative conducting phase of the brushless direct current motor in the three-phase inverter are conducted, and the hybrid energy storage unit and the other power tubes in the three-phase inverter are all turned off, a formed voltage vector is used as an electric second vector V_m,c1；

When the first power MOS tube in the hybrid energy storage unit is conducted, the upper bridge arm power tube in the positive conducting phase of the brushless direct current motor in the three-phase inverter is conducted with the lower bridge arm power tube in the negative conducting phase of the brushless direct current motor, and the other power tubes in the hybrid energy storage unit and the three-phase inverter are all turned off, the formed voltage vector is used as an electric third vector V_m,s1；

When only the upper bridge arm power tube on the positive conducting phase of the brushless DC motor in the three-phase inverter is conducted or only the lower bridge arm power tube on the negative conducting phase of the brushless DC motor in the three-phase inverter is conductedWhen the rate tube is conducted and the other power tubes in the three-phase inverter are turned off, the formed voltage vector is used as an electric fourth vector V no matter what the switching state of the power tubes in the hybrid energy storage unit is_m,0；

3.2) when the motor runs in an accelerated mode, the combined action of different vectors meets the following relation:

when the brushless DC motor is in the line voltage u between the positive conducting phase and the negative conducting phase_pn≤d_maxu_bWhile, using a motorized first vector V_m,b1And electromotive fourth vector V_m,0Coact and satisfy:

u_pn＝d_m,b1u_b＝2E+2R_sI

wherein d is_maxA constraint duty cycle for limiting the magnitude of the output current of the battery during acceleration, and d_max＝I_bat,max/I，I_bat,maxIs the maximum output current of the battery, u_bIs the voltage of the storage battery, and the voltage of the storage battery is equal to the rated voltage u of the brushless direct current motor_N，d_m,b1Is a motor-driven first vector V_m,b1Duty ratio of R_sE is the phase resistance and the opposite potential of the brushless DC motor respectively, and I is the phase current amplitude of the brushless DC motor;

when u is_pn>d_maxu_bWhile, using a motorized first vector V_m,b1And electric third vector V_m,s1And electromotive fourth vector V_m,0Coact and satisfy:

u_pn＝d_maxu_b+d_m,s1u_sc＝2E+2R_sI

wherein d is_m,s1As a third electric vector V_m,s1Duty ratio of u_scIs the super capacitor voltage;

when u is_pn>d_max(u_b+u_sc) While, using a motorized third vector V_m,s1Electric second vector V_m,c1And electromotive fourth vector V_m,0Coact and satisfy:

u_pn＝d_maxu_b+(d_max+d_m,c1)u_sc

wherein d is_m,c1Is a second vector V of electric motion_m,c1Duty cycle of (d);

3.3) when the motor operates at constant speed, the electric third vector V is adopted in the phase change stage_m,s1And electromotive fourth vector V_m,0Coact and satisfy:

2d_m,s1(u_b+u_sc)＝4E+3R_sI+u_b+u_sc。

according to the invention, a novel hybrid energy storage unit is designed through the steps, when the motor brakes and operates in a decelerating mode, the braking energy is fed back to the super capacitor while the braking torque control is realized through the combined action of different vectors; when the motor runs in an accelerating way, the sharing control of the output power of the super capacitor and the storage battery is realized through the combined action of different vectors; when the motor operates at a constant speed, the commutation torque fluctuation suppression is realized through the combined action of different vectors.

The method ensures that the brushless direct current motor obtains good control performance in braking deceleration, acceleration and constant speed operation modes through the steps, meets various requirements in practical application, and can well relieve the influence of frequent charging and discharging on the service life of the storage battery by using the super capacitor as an energy buffer device.

The invention has the beneficial effects that:

(1) the hybrid energy storage unit is composed of a storage battery, a super capacitor and a power tube, and an additional inductance device is not needed, so that the size of a brushless direct current motor driving system is reduced.

(2) In the braking and decelerating operation process, the motor converts mechanical energy into electric energy to feed back to the super capacitor, so that the energy utilization rate is improved, and the adverse effect on the storage battery caused by frequent charging is avoided.

(3) In the process of accelerating operation, the super capacitor is used for assisting the storage battery to supply power to the motor, so that the problem of shortened service life of the storage battery caused by overhigh output power is effectively solved.

(4) In the constant-speed operation process, high-voltage output is realized by connecting the super capacitor and the storage battery in series at the phase change moment, so that the phase change torque fluctuation of the brushless direct current motor is effectively inhibited, and the operation stability of the motor is improved.