WO2024040609A1

WO2024040609A1 - Motor driver and motor driving system

Info

Publication number: WO2024040609A1
Application number: PCT/CN2022/115275
Authority: WO
Inventors: 廖华
Original assignee: 西门子股份公司; 西门子（中国）有限公司
Priority date: 2022-08-26
Filing date: 2022-08-26
Publication date: 2024-02-29

Abstract

Provided is a motor driver (30), comprising: a passive alternating-current (AC)/direct-current (DC) converter (310), a DC link circuit (320), an inverter (330), and a filter circuit (340). The passive AC/DC converter (310) comprises three AC/DC conversion branch circuits and is used for converting an inputted AC voltage into a DC voltage. The DC link circuit (320) is connected to the passive AC/DC converter (310), is used for filtering the DC voltage outputted by the passive AC/DC converter (310), and comprises: a capacitor circuit comprising first and second capacitors which are connected in series, the capacitor circuit being provided between a positive electrode output end and a negative electrode output end of the passive AC/DC converter (310); and a fourth DC/AC conversion branch circuit (3201) comprising two switching devices. The inverter (330) comprises first to third DC/AC conversion branch circuits (3301, 3302, 3303) arranged in parallel between the positive electrode output end and the negative electrode output end, wherein the first to third DC/AC conversion branch circuits each comprise two switching devices. The filter circuit (340) comprises first to fourth filters, which are respectively arranged between a node located between the first and second capacitors and a node located between the two switching devices in each of the first to fourth DC/AC conversion branch circuits (3301, 3302, 3303, 3201).

Description

Motor Drivers and Motor Drive Systems

Technical field

The present disclosure relates generally to the field of circuit technology, and more specifically, to a motor driver and a motor drive system.

Background technique

Frequency converters (VFC) are widely used in motor drive and servo industries. In most cases, capacitors are used in DC links as power supply decoupling devices. During motor braking, regenerative energy will be applied to the DC link capacitor, causing the DC voltage to rise. If the voltage continues to rise above the allowed operating voltage, the DC capacitor may be damaged. For VFCs with basic rectifier input, regenerative energy cannot be fed back to the grid. Typically, a braking resistor is used to dissipate regenerated energy to prevent overvoltage damage to components.

On the other hand, a VFC using PWM technology will generate high-frequency common-mode voltages on the motor, which causes bearing currents and may lead to severe bearing damage. In addition, high-frequency leakage current can cause EMI problems. In order to suppress these adverse effects and improve reliability, the output common-mode voltage of the inverter should be limited.

Figure 1 is a general motor drive topology with a three-phase diode bridge input. Three-phase two-level IGBT half-bridge is used in DC/AC inverter. A large braking resistor R1 is connected to the DC link via switch T8. If the DC voltage rises to the limit value, T8 will be activated and R1 will absorb the overvoltage. Add a freewheeling diode D7 to eliminate the instantaneous overvoltage caused by the stray inductance of the braking resistor R1. However, braking resistor R1 needs to dissipate the regenerative energy of the motor, so it should have higher power capacity and larger volume. At the same time, it is usually customized, so the cost is quite expensive. The most important thing is that large dissipated power will generate high temperatures inside the resistor, even as high as hundreds of degrees Celsius, which will bring serious challenges to the heat sink and structural design of the entire system.

In order to reduce the impact of the common-mode voltage on the motor, a filter can be added to the output end, as shown in Figure 2. However, this method can only reduce the common-mode voltage to a smaller value and cannot completely eliminate the common-mode voltage.

Contents of the invention

The following provides a brief summary of the invention in order to provide a basic understanding of certain aspects of the invention. It should be understood that this summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. The purpose is merely to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

In view of the above, the present disclosure provides a motor driver capable of eliminating common mode voltage and overvoltage damage.

According to an aspect of the present disclosure, a motor driver is provided, including: a passive AC/DC converter, a DC link circuit, an inverter and a filter circuit, wherein,

The passive AC/DC converter includes three AC/DC conversion branch circuits for converting AC voltage input to the motor driver into DC voltage;

The DC link circuit is connected to the passive AC/DC converter and is used to filter the DC voltage output by the passive AC/DC converter. The DC link circuit includes:

a capacitor circuit including a first capacitor and a second capacitor in series, disposed between the positive and negative output terminals of the passive AC/DC converter; and

A fourth DC/AC conversion branch circuit including two switching devices, the fourth DC/AC conversion branch circuit being connected in parallel with the capacitor circuit;

The inverter includes first to third DC/AC conversion branch circuits arranged in parallel between the positive and negative output terminals of the DC link circuit, and the first to third DC/AC conversion branch circuits Each of them respectively includes two switching devices;

The filter circuit includes first to fourth filters, wherein the first to fourth filters are respectively disposed at a node between the first capacitor, the second capacitor and the first to fourth DC/AC Switch between nodes in a branch circuit between two switching devices.

In this way, high-frequency common-mode voltages and overvoltage damage generated by the inverter can be completely eliminated.

Optionally, in an example of the above aspect, the motor driver further includes a rechargeable battery,

The rechargeable battery is connected between the inductor in the fourth filter of the filter circuit and the negative electrode of the DC link circuit,

Wherein, when the motor driver operates in the braking regeneration mode, the regenerative energy generated during braking is stored in the rechargeable battery.

In this way, the regenerative energy generated during braking can be stored in the rechargeable battery, thereby effectively utilizing the regenerative energy. In addition, for low-voltage servo drives, an external power supply is required as an auxiliary power supply and a motor-holding braking power supply, so rechargeable batteries can also be directly used as an auxiliary power supply and motor-holding braking power supply.

Optionally, in an example of the above aspect, the first capacitor and the second capacitor are capacitors with the same capacitance value, and the switching device is a switching device of the same type.

Optionally, in an example of the above aspect, the switching device includes a fully controlled power transistor and a diode, and the anode and cathode of the diode are respectively connected to the emitter and collector of the fully controlled power transistor.

Optionally, in an example of the above aspect, the fully controlled power transistor includes an insulated gate bipolar transistor.

Optionally, in an example of the above aspect, the switching device includes a fully controlled power field effect transistor and a diode, and the anode and cathode of the diode are respectively connected to the source and drain of the fully controlled power field effect transistor. Extremely connected.

Optionally, in an example of the above aspect, the fully controlled field effect transistor includes a fully controlled enhancement type field effect transistor or a fully controlled depletion type field effect transistor.

Each of the first to fourth filters includes one of the following filters: LC filter, LCL filter.

Optionally, in an example of the above aspect, the inverter uses pulse width modulation to control the output common mode voltage to be 0.

According to another aspect of the present disclosure, a motor driving system is provided, including a motor driver according to the above and a motor, the motor driver being used to drive the motor, wherein,

When the motor operates in normal mode, the common mode voltage of the motor is controlled to zero,

When the motor operates in the braking regeneration mode, the regenerative energy generated during the braking process of the motor is stored in the rechargeable battery of the motor driver.

According to the motor driver of the present disclosure, the fourth DC/AC conversion branch circuit added in the DC link circuit can realize different functions in different operating modes. In the normal operating mode of the motor driver, the inverter containing the fourth branch circuit can use appropriate PWM (pulse width modulation) technology to eliminate the motor common mode voltage; in the motor braking state, the fourth branch circuit can be used to Store regenerative energy in rechargeable batteries. Therefore, the technical solution according to the present disclosure has at least one of the following advantages:

Circuit topologies according to the present disclosure can eliminate common-mode voltages and mitigate possible damage to motor bearings, thus improving system reliability.

There is no need to use a larger and heat-generating braking resistor in the circuit topology, which is beneficial to the system thermal design and can eliminate the impact of the braking resistor on other heat-sensitive components.

In addition, by adding an additional rechargeable battery, the motor braking regenerative energy can be stored, which is beneficial to energy conservation.

Description of drawings

The above and other objects, features and advantages of the present invention will be more easily understood with reference to the following description of the embodiments of the present invention in conjunction with the accompanying drawings. The components in the drawings are merely illustrative of the principles of the invention. In the drawings, the same or similar technical features or components will be represented by the same or similar reference numbers. In the attached picture:

Figure 1 is a circuit topology diagram of a motor driver in the prior art.

Figure 2 is a circuit topology diagram of another motor driver in the prior art.

3 is a circuit topology diagram of a motor driver according to an embodiment of the present disclosure.

4 is a circuit topology diagram of a motor driver according to another embodiment of the present disclosure.

Among them, the reference signs are as follows:

30: Motor driver 310: Passive AC/DC converter

320: DC link circuit 330: Inverter

340: Filter circuit 3301: First DC/AC conversion branch circuit

3302: Second DC/AC conversion branch circuit 3303: Third DC/AC conversion branch circuit

3201: Fourth DC/AC conversion branch circuit 350: Rechargeable battery

Detailed ways

The subject matter described herein will now be discussed with reference to example implementations. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and are not intended to limit the scope, applicability, or examples set forth in the claims. Changes may be made in the function and arrangement of the elements discussed without departing from the scope of the disclosure. Each example may omit, substitute, or add various procedures or components as needed. For example, the described methods may be performed in an order different from that described, and individual steps may be added, omitted, or combined. Additionally, features described with respect to some examples may also be combined in other examples.

As used herein, the term "includes" and variations thereof represent an open term meaning "including, but not limited to." The term "based on" means "based at least in part on." The terms "one embodiment" and "an embodiment" mean "at least one embodiment." The term "another embodiment" means "at least one other embodiment". The terms "first", "second", etc. may refer to different or the same object. Other definitions may be included below, whether explicit or implicit. The definition of a term is consistent throughout this specification unless the context clearly dictates otherwise.

FIG. 3 shows an example circuit topology diagram of motor driver 30 according to one embodiment of the present disclosure. As shown in FIG. 3 , the motor driver 30 includes a passive AC/DC converter 310 , a DC link circuit 320 , an inverter 330 , and a filter circuit 340 .

The passive AC/DC (alternating current/direct current) converter 310 is used to convert the AC voltage input to the motor driver 30 into a DC voltage.

The passive AC/DC converter 310 includes three AC/DC conversion branch circuits, each branch circuit including two diodes connected in series in the same direction, such as diodes D1, D2, D3, D4, D5 and D6. The input terminals R, S and T of the three-phase power supply of the motor driver are respectively connected to the node between the two diodes of the corresponding branch circuit.

The DC link circuit 320 is connected to the passive AC/DC converter 310 and is used to filter the DC voltage output by the passive AC/DC converter 310 .

Specifically, the DC link circuit 320 includes a first capacitor Ca, a second capacitor Cb, and switching devices T7 and T8. Wherein, the first capacitor Ca and the second capacitor Cb are disposed in series between the positive output terminal and the negative output terminal of the passive AC/DC converter 310, and preferably, the first capacitor Ca and the second capacitor Cb are the same capacitor. In addition, in other examples of the present invention, the first capacitor Ca and the second capacitor Cb may be respectively composed of multiple capacitors in parallel, series or mixed connection. In this case, the first capacitor Ca and the second capacitor Cb The same Cb means that the type, quantity and composition of the components of the capacitor are exactly the same.

The switching device T7 and the switching device T8 are connected in series, and the switching device T7 is connected to the positive output terminal of the passive AC/DC converter 310 , and the switching device T8 is connected to the negative output terminal of the passive AC/DC converter 310 . Here, the switching device T7 and the switching device T8 actually constitute the fourth DC/AC conversion branch 3201. In the present disclosure, switching devices T7 and T8 are the same switching devices. As shown in the figure, the switching device T7 is composed of a single fully controlled power transistor and a single diode. The anode and cathode of the diode are connected to the emitter and collector of the fully controlled power transistor respectively. In other examples of the present disclosure, the single fully controlled power transistor may be composed of multiple fully controlled power transistors in parallel, series, or mixed connection. Similarly, the single diode can also be composed of multiple diodes connected in parallel, series or mixed connection. In the present disclosure, the fully controlled power transistor is, for example, an insulated gate bipolar transistor (IGBT).

In other examples of the present disclosure, the switching device T7 may also be composed of a single fully controlled power field effect transistor and a single diode. The anode and cathode of the diode are respectively connected to the source and drain of the fully controlled power field effect transistor. Extremely connected. Similarly, in other examples of the present disclosure, the single fully controlled power field effect transistor may be composed of multiple fully controlled power field effect transistors in parallel, series or mixed connection. Similarly, the single diode can also be composed of multiple diodes connected in parallel, series or mixed connection. In this example, the fully controlled power field effect transistor is, for example, a fully controlled enhancement mode field effect transistor or a fully controlled depletion mode field effect transistor.

The inverter 330 is connected to the DC link circuit 320 and includes three parallel first to third DC/AC (direct current/alternating current) conversion branch circuits for converting the DC voltage output by the DC link circuit into an AC voltage.

Specifically, the inverter 330 includes first to third DC/AC

conversion branch circuits

3301, 3302, and 3303 arranged in parallel between the positive output terminal and the negative output terminal of the DC link circuit 320. The first to third DC / Each of the AC

conversion branch circuits

3301, 3302, and 3303 is composed of two switching devices T1, T2, T3, T4, T5, and T6, where the switching devices T1, T2, T3, T4, T5, and T6 are The switching device T7 is the same switching device.

The filter circuit 340 is connected to the DC link circuit 320 and the inverter 330, and is used to filter the voltage output by the DC link circuit 320 and the inverter 330.

Specifically, the filter circuit includes a node O and two of the first to fourth DC/AC

conversion branch circuits

3301, 3302, 3303, and 3201 respectively disposed between the first capacitor Ca and the second capacitor Cb. Switch devices between the first to fourth filters between nodes V1, V2, V3 and V4. As shown in Figure 3, the first filter is an LC-type filter composed of an inductor L1 and a capacitor C1 connected in series, the second filter is an LC-type filter composed of an inductor L2 and a capacitor C2 connected in series, and the third filter The first filter is an LC type filter composed of an inductor L3 and a capacitor C3 connected in series, and the fourth filter is an LC type filter composed of an inductor L4 and a capacitor C4 connected in series. Here, L1 to L4, R1 to R4 and C1 to C4 can take the same parameters. In other examples of the present disclosure, each of the first to fourth filters may also adopt an LCL type filter.

One end of the inductor L1 in the first filter is connected to the node V1 of the two switching devices T1 and T2 in the first DC/AC conversion branch circuit 3301, and one end of the capacitor C1 is connected to the first capacitor Ca and the second capacitor Node O of Cb is connected. One end of the inductor L2 in the second filter is connected to the node V2 of the two transistors T3 and T4 in the second DC/AC conversion branch circuit 3302, and one end of the capacitor C2 is connected to the first capacitor Ca and the second capacitor Cb. Node O is connected.

One end of the inductor L3 in the third filter is connected to the node V3 of the two switching devices T5 and T6 in the first DC/AC conversion branch circuit 3303, and one end of the capacitor C3 is connected to the first capacitor Ca and the second capacitor Node O of Cb is connected. One end of the inductor L4 in the fourth filter is connected to the node V4 of the two switching devices T7 and T8 in the fourth DC/AC conversion branch circuit 3201, and one end of the capacitor C4 is connected to the first capacitor Ca and the second capacitor Cb The node O is connected.

What should be noted here is that only one of the two switching devices in each circuit of the first to fourth DC/AC conversion branch circuits is in the on state and the other is in the off state at each moment during normal operation of the motor driver.

When the motor driver shown in Figure 3 is working under normal operating conditions, the switching devices T7 and T8 can be regarded as the fourth DC/AC conversion branch circuit. It can be deduced theoretically that the common mode voltage Vcm of the motor can be expressed for:

V _1O to V _4O are the output voltages of the four branch circuits respectively connected to the node O between the first capacitor Ca and the second capacitor Cb in the DC link circuit. According to the inverter PWM mechanism, if the upper side IGBT of each branch is turned on, the output of the phase is +Vdc; if the lower side IGBT is turned on, the output of the phase is -Vdc. The possible states of motor operation V _1o , V _2o , and V _3o are 1 positive and 2 negative, or 1 negative and 2 positive. Then according to the states of V _1o , V _2o , and V _3o , control V _4o accordingly, let 4 Each branch maintains 2 positive and 2 negative, so that the overall common mode voltage Vcm can be controlled to 0, and the output voltage V _1o ~ V _4o is compensated, and we can get:

V _1o +V _2o +V _3o +V _4o =0

Therefore, with the motor driver shown in Figure 3, the high voltage generated by the inverter can be completely eliminated by including a DC/AC conversion branch circuit in the DC link circuit that is the same as the DC/AC conversion branch in the inverter. Frequency common mode voltage and overvoltage damage.

FIG. 4 shows an example circuit topology diagram of motor driver 30 according to another embodiment of the present disclosure.

The motor driver 30 shown in Figure 4 also includes a passive AC/DC converter 310, a DC link circuit 320, an inverter 330 and a filter circuit 340. The topology of these parts is similar to that of the motor driver 30 shown in Figure 3 The topology of the corresponding parts is the same. When the motor driver shown in Figure 4 operates in the normal mode, similar to the operation described above with reference to Figure 3, the common mode voltage can be eliminated, which will not be described in detail here.

The motor driver 30 in Figure 4 also includes a rechargeable battery 350. Specifically, a rechargeable battery 350 is connected between the inductor L4 in the fourth filter of the filter circuit 340 and the negative electrode of the DC link circuit. For example, a 24V rechargeable battery can be used.

When the motor driver shown in Figure 4 operates in the brake regeneration mode, the switching devices T7 and T8 and the inductor L4 can be regarded as a step-down converter. If the DC link voltage is greater than the protection voltage, the switching device T7 will be activated, and the regenerative energy generated during the braking process can be stored in the rechargeable battery 350, thereby effectively utilizing the regenerative energy. In addition, for low-voltage servo drives, an external power supply is required as an auxiliary power supply and a motor-holding braking power supply, so the rechargeable battery 350 can also be directly used as an auxiliary power supply and motor-holding braking power supply.

Eliminating the need to use a larger and heat-generating braking resistor in the circuit topology is beneficial to system thermal design and can eliminate the impact of the braking resistor on other thermal sensing components.

The detailed description set forth above in conjunction with the drawings describes exemplary embodiments and does not represent all embodiments that can be implemented or that fall within the scope of the claims. The term "exemplary" as used throughout this specification means "serving as an example, instance, or illustration" and does not mean "preferred" or "advantageous" over other embodiments. The detailed description includes specific details for the purpose of providing an understanding of the described technology. However, these techniques can be implemented without these specific details. In some instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the concepts of the described embodiments.

The above description of the disclosure is provided to enable any person of ordinary skill in the art to make or use the disclosure. Various modifications to the disclosure will be apparent to those of ordinary skill in the art, and the general principles defined herein may be applied to other modifications without departing from the scope of the disclosure. . Thus, the present disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

The above descriptions are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention shall be included in the present invention. within the scope of protection.

Claims

A motor driver (30), including: a passive AC/DC converter (310), a DC link circuit (320), an inverter (330) and a filter circuit (340), wherein,

The passive AC/DC converter (310) includes three AC/DC conversion branch circuits for converting the AC voltage input to the motor driver (30) into a DC voltage;

The DC link circuit (320) is connected to the passive AC/DC converter (310) and is used to filter the DC voltage output by the passive AC/DC converter (310). The DC link circuit (320) includes :

a capacitor circuit including a first capacitor (Ca) and a second capacitor (Cb) disposed between the positive and negative output terminals of the passive AC/DC converter (310); and

A fourth DC/AC conversion branch circuit (3201) including two switching devices (T7, T8), the fourth DC/AC conversion branch circuit (3201) is connected in parallel with the capacitor circuit;

The inverter (330) includes first to third DC/AC conversion branch circuits (3301, 3302, 3303) arranged in parallel between the positive and negative output terminals of the DC link circuit (320), so Each of the first to third DC/AC conversion branch circuits (3301, 3302, 3303) respectively includes two switching devices (T1, T2, T3, T4, T5, T6);

The filter circuit (340) includes first to fourth filters, wherein the first to fourth filters are respectively disposed at nodes (Ca, Cb) between the first capacitor and the second capacitor (Ca, Cb). O) Between the two switching devices (T1, T2, T3, T4, T5, T6, T7, T8) in the first to fourth DC/AC conversion branch circuits (3301, 3302, 3303, 3201) between the nodes (V1, V2, V3, V4).
The motor driver (30) of claim 1, further comprising a rechargeable battery (350),

The rechargeable battery (350) is connected between the inductor (L4) in the fourth filter of the filter circuit (340) and the negative electrode of the DC link circuit,

Wherein, when the motor driver (30) operates in the braking regeneration mode, the regenerative energy generated during braking is stored in the rechargeable battery (350).
The motor driver (30) according to claim 1 or 2, wherein the first capacitor (Ca) and the second capacitor (Cb) are capacitors with the same capacitance value, and the switching device (T1, T2, T3, T4, T5, T6, T7, T8) are the same type of switching devices.
The motor driver (30) according to claim 1 or 2, wherein the switching device (T1, T2, T3, T4, T5, T6, T7, T8) includes a fully controlled power transistor and a diode, the diode The anode and cathode are respectively connected to the emitter and collector of the fully controlled power transistor.
The motor driver (30) of claim 4, wherein the fully controlled power transistor is an insulated gate bipolar transistor.
The motor driver (30) according to claim 1 or 2, wherein the switching devices (T1, T2, T3, T4, T5, T6, T7, T8) include fully controlled power field effect transistors and diodes, so The anode and cathode of the diode are respectively connected to the source and drain of the fully controlled power field effect transistor.
The motor driver (30) according to claim 6, wherein the fully controlled field effect transistor is a fully controlled enhancement type field effect transistor or a fully controlled depletion type field effect transistor.
The motor driver (30) according to claim 1 or 2, wherein each of the first to fourth filters includes one of the following filters: LC filter, LCL filter.
The motor driver (30) according to claim 1 or 2, wherein the inverter (330) uses pulse width modulation to control the output common mode voltage to be 0.
A motor drive system, including a motor driver according to any one of claims 1-9 and a motor, the motor driver being used to drive the motor, wherein,

When the motor operates in normal mode, the common mode voltage of the motor is controlled to zero,

When the motor operates in the braking regeneration mode, the regenerative energy generated during the braking process of the motor is stored in the rechargeable battery of the motor driver.