A topology and method for assisting motor self-boosting operation by passive devices

Abstract

The application provides a solution for realizing self-boosting operation of a motor by combining a passive device with a motor driver. The solution uses an inductance auxiliary inverter to realize boosting and reducing of a suspended capacitor by controlling the proportion of two zero vectors V 000 and V 111 , to realize the series connection of the suspended capacitor and the power supply, to supply power for the inverter, to realize boosting of the inverter power supply, to improve the voltage, and to expand the speed range of the motor. The application fully utilizes the power switching devices in the original motor inverter, and does not need additional power switching devices. The cost is saved, and the reliability of the system is increased. Meanwhile, the inductance current is changed by changing the time difference of the two zero voltage vectors, thereby realizing the charging of the suspended capacitor, and the effective voltage vector time is unchanged, so that the performance of the motor is not affected. By adjusting the voltage of the suspended capacitor, the highest speed of the motor can be improved to twice the base speed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of power electronics, and relates to a boost topology and method, in particular to a topology and method for realizing boost based on a passive device auxiliary three-phase motor drive system. BACKGROUND

[0002] With the rapid development of electric drive in industry and household appliances, built-in permanent magnet synchronous motor and its drive system are increasingly concerned.

[0003] Among all key technologies, due to the influence of back electromotive force of permanent magnet motor, voltage utilization rate becomes one of the most important factors affecting motor performance. Generally, the maximum output speed range of built-in permanent magnet synchronous motor drive is largely dependent on the DC bus voltage and its utilization rate. Therefore, it is crucial to improve the DC bus voltage utilization rate to expand the motor operating range.

[0004] To solve the problem of low voltage utilization and achieve a higher speed operating range, many methods have been proposed in recent years. Literature 1 [Literature 1 is V. Bist and B. Singh, "An adjustable-speed PFC bridgeless buck-boost converter-fed BLDC motor drive," IEEE Trans. Ind. Electron., vol. 61, no. 6, pp. 2665-2677, Jun. 2014. (Journal paper)] integrates the buck-boost conversion into the front-end power factor corrector, saves the cost at the same time, and achieves a wider operating range by adjusting the DC bus voltage. Literature 2 [Literature 2 is H. Matsumoto, Y. Neba, and H. Asahara, "Variable-form carrier-based PWM for boost-voltage motor driver with a charge-pump circuit," IEEE Trans. Ind. Electron., vol. 62, no. 8, pp. 4728-4738, Aug. 2015. (Journal paper)] uses the charge pump circuit of the super capacitor to control the power switch state in the proposed circuit, thereby generating different DC bus voltages. In literature 3 [Literature 3 is Y. S. Lin, K. W. Hu, T. H. Yeh, and C. M. Liaw, "An electric-vehicle IPMSM drive with interleaved front-end DC / DC converter," IEEE Trans. Veh. Technol., vol. 65, no. 6, pp. 4493-4504, Jun. 2016. (Journal paper)], the motor driver uses an interleaved bidirectional DC / DC converter. The converter can increase the DC bus voltage according to the operating conditions of the motor, while also allowing power transmission to the battery. Although these methods increase the DC bus voltage, thereby expanding the operating range of the permanent magnet motor, these solutions require additional hardware support, especially power electronic switches, and the use of these active devices reduces the reliability of the system, limiting their applications. SUMMARY

[0005] OBJECTIVES

[0006] To solve the problem of low voltage utilization, and achieve higher speed operating range, usually use boost and buck circuit with power switch tube to achieve. But this will increase the cost of the system, and the damaged active device reduces the reliability of the system. The present application makes full use of the power switch device of the AC motor driver, without additional power switch device, saves cost, and increases the reliability of the system. At the same time, the control method proposed in the application does not affect the normal operation of the motor while boosting. By boosting operation, the voltage utilization of the motor is increased, and the speed of the motor is improved.

[0007] Technical scheme

[0008] Reference Figure 1 The motor drive system for realizing motor self-boosting by using passive device auxiliary motor drive, without changing the topology structure of the conventional three-phase motor drive, increases the peripheral passive device, characterized in that: the negative pole of the motor inverter is connected to the negative pole of the power supply, the positive pole of the inverter is connected to the positive pole of the floating capacitor, and the negative pole of the floating capacitor is connected to the positive pole of the power supply. The three terminals of one end of the three auxiliary inductors are shorted together to form a common terminal and are connected to the positive pole of the power supply, and the three terminals of the other end are connected to the three-phase output terminals of the motor inverter. At the same time, a current sensor is placed between the positive pole of the power supply and the common terminal of the three auxiliary inductors.

[0009] A method for realizing motor self-boosting operation by using passive device auxiliary motor drive based on the above topology structure, comprising the following steps:

[0010] Step 1: floating capacitor voltage outer loop control

[0011] From Figure 1 According to the topology structure, the floating capacitor and the power supply are connected in series to supply power to the inverter. The given value of the floating capacitor voltage is calculated according to the target voltage of the motor required for boosting operation. The voltage of the floating capacitor is used as the outer loop feedback value for closed loop operation. The given value and the feedback value of the floating capacitor voltage are compared, and the target charging current of the auxiliary inductor is calculated through PI regulation.

[0012] Step 2: auxiliary inductor current inner loop control

[0013] The sum of the currents flowing through the three auxiliary inductors is used as the inner loop feedback value for closed loop control. The target charging current of the auxiliary inductor in step 1 and the inner loop feedback value are compared, and the action time difference of two zero vectors V 000 and V 111 is calculated through PI regulation, so as to calculate the compensation amount ΔK of the comparison value, as shown in formula (1):

[0014]

[0015] Where: T0 is the zero vector V 000T7 is zero vector V 111 T7 is zero vector V s T7 is zero vector V

[0016] Step three: comparison value compensation

[0017] The motor uses the normal seven-segment vector control method to calculate the comparison value, and the carrier of PWM is set to the increment-decrement mode. The PWM comparison value K A , K B , K C is calculated

[0018]

[0019] K A ', K B ', K C ' are the comparison values of the compensated A, B, and C three-phase PWM waves, respectively.

[0020] The compensated comparison values K A ', K B ', K C ' are used to generate the corresponding PWM waves to control the action of the inverter power switching elements, realizing the voltage boost operation of the motor.

[0021] Advantages

[0022] Compared with the previous motor voltage boost operation method, this method has the following advantages:

[0023] (1) In the proposed topology, the power switching devices in the original motor inverter are fully utilized without the need for additional power switching devices. Cost is saved, and system reliability is increased.

[0024] (2) In the proposed control method, the regulation of inductor current only needs to change the difference in the action time of zero voltage vector, without changing the action time of effective voltage vector. Therefore, the performance of the motor is not affected.

[0025] (3) By controlling the voltage of the suspension capacitor, the maximum speed of the motor can be extended to twice the base speed. Voltage utilization is increased, and the speed of the motor is improved. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is a topology diagram for realizing motor self-voltage boost operation by using passive devices to assist motor driver.

[0027] Figure 2 It is the PWM waveform of the vector control method in the first sector,Figure 2 (a) is a PWM waveform of the conventional seven-segment vector control method, Figure 2 (b) is a PWM waveform of the compensated seven-segment vector control method.

[0028] In Figure 1 , C1 is a suspension capacitor for improving the output voltage value of the inverter, C2 represents the support capacitor of the DC power supply U DC , u C1 and u C2 are the voltage values of the capacitors C1 and C2 respectively, S1 to S6 are six power switch tubes of the inverter, the permanent magnet synchronous motor and the current sensor are marked in the figure, L A1 , L B1 , L C1 represent three auxiliary capacitors, wherein i LA1 , i LB1 , i LC1 represent the currents flowing through the three inductors, i L represents the sum of the three auxiliary inductor currents, i A , i B and i C are three-phase currents of the motor, and the arrow direction in the figure represents the specified positive direction of the current.

[0029] In Figure 2 , V1 and V2 are effective vectors V 100 and V 110 , V0 and V7 are zero vectors V 000 and V 111 , T0, T1, T2 and T7 represent the action time corresponding to the vectors V0, V1, V2 and V7 respectively, T S is the carrier cycle, T zero is the sum of the action time of the two zero vectors, S A , S B , S C are the PWM waves of the power switch tubes on the three-phase inverter, K is the set value of the carrier lift count, K A , K B , K C are the comparison values of the three PWM waves of the conventional seven-segment vector control method, K A ', K B ', K C ' are the comparison values of the three PWM waves of the compensated seven-segment vector control method. DETAILED DESCRIPTION

[0030] The application will be further described below in combination with the embodiments. Given the power supply voltage is 25V, the specified motor operating voltage is 50V, at this time, the power supply needs to charge the suspension capacitor to 25V.

[0031] Step 1: according to the topology connection as Figure 1 The given value of the suspension capacitor is set to 25V. At the beginning of operation, the voltage of the suspension capacitor is zero, at this time the difference between the given value and the feedback value is 25V, after PI adjustment, the target value of the auxiliary inductor is I set .

[0032] Step 2: At the beginning of operation, the current flowing through the three auxiliary inductors is 0, at this time, the I set calculated in step 1 is compared with the inner loop feedback value, and through PI adjustment, the action time difference of two zero vectors V 000 and V 111 is calculated, at this time the difference is large, so the action time T0 of V 000 is greater than the action time T7 of V 111 . Assuming that at this time, the action time of the two zero voltage vectors and T zero accounts for 40% of T s , T0 accounts for 70% of T zero , and T7 accounts for 30% of T zero . Using formula (1), ΔK = 0.08K can be calculated.

[0033] Step 3: Assuming that the motor is compared with the normal seven-segment vector control method, the traditional seven-segment vector control PWM waveform is shown in Figure 2 (a). Using the ΔK calculated in step 2 combined with formula (2) for compensation, the compensated PWM waveform is shown in Figure 2 (b).

[0034] Using the compensated comparison values K A ', K B ', and K C ' to generate corresponding PWM waves to control the action of the inverter power switching elements and achieve motor control.

Claims

1. A topology structure for realizing self-boosting operation of a motor by using passive devices to assist a motor driver, characterized in that: the topology does not change the topology structure of the motor driver, and passive devices are introduced on the basis of the motor and the driver thereof, and the topology structure is that: the negative electrode of the motor inverter is connected to the negative electrode of the power supply, the positive electrode of the inverter is connected to the positive electrode of the floating capacitor, and the negative electrode of the floating capacitor is connected to the positive electrode of the power supply; three terminals of one end of the three auxiliary inductors are short-circuited together to form a common terminal and are connected to the positive electrode of the power supply, and three terminals of the other end are connected to three-phase output terminals of the motor inverter.

2. A method for realizing self-boosting operation of a motor by using passive devices and a motor driver based on the topology structure according to claim 1, comprising the following steps: step one: floating capacitor voltage outer loop control; the floating capacitor and the power supply are connected in series to supply power to the inverter together; the given value of the floating capacitor voltage is calculated according to the target voltage required by the motor for the boosting operation; the voltage of the floating capacitor is used as the outer loop feedback value for closed-loop operation; the given value and the feedback value of the voltage of the floating capacitor are compared, and the target charging current of the auxiliary inductor is calculated through PI regulation; step two: auxiliary inductor current inner loop control; step three: comparison value compensation; the corresponding PWM wave is generated by using the compensated comparison value to control the action of the power switch element of the inverter, thereby realizing the control of the motor. ​ ​ ​ ​ The sum of the currents flowing through the three auxiliary inductors is taken as the inner loop feedback value for closed-loop control; the target charging current of the auxiliary inductor in step 1 and the inner loop feedback value are compared, and the time difference of the actions of V 000 and V 111 is used to calculate the compensation amount ΔK of the comparison value, as shown in formula (1): Iaux1=Iaux2=Iaux3=Iaux0 (1) wherein: T0 is a zero vector V 000 T7 is a zero vector V 111 K is a time base period register value set in the increment / decrement count mode, T s is a carrier period; ​ The method of seven-segment vector control for motor compares the calculation of value, the carrier of PWM is set to increase and decrease counting mode, and the PWM comparison value K is calculated A , K B , K C , then the ΔK calculated in step 2 is compensated, and the calculation method is shown in formula (2): Wherein: K A ', K B ', K C ' are the comparison values of the compensated A, B, C three-phase PWM waves, respectively. ​

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