KR20180108959A - Parallel motor system and operating method thereof - Google Patents

Abstract

The present invention relates to a method of operating a parallel motor system comprising a plurality of motors connected in parallel to a power supply. The method of operation of a parallel motor system includes the steps of forming a maximum torque reserve state in a drive inverter corresponding to each of the motors, torque index information including information on the torque of each of the motors, Generating a link voltage corresponding to each of the motors based on the voltage and operating each of the motors by applying the link voltage to the drive inverter in the maximum torque reserve state, The switching frequency of the switching elements included in the drive inverter is determined to be a specific value regardless of the torque of each of the motors in the maximum torque reserve state.

Description

PARALLEL MOTOR SYSTEM AND OPERATING METHOD THEREOF FIELD OF THE INVENTION [0001]

The present invention relates to a parallel motor system, and more particularly to a parallel motor system using a brushless DC motor and a method of operating the same.

Engines (such as motors and internal combustion engines) are key components that have led technology development since the Industrial Revolution. These engines are not only industrial devices such as factories, power plants, transportation equipment such as automobiles, ships, airplanes, but also household appliances such as refrigerators, washing machines, and air conditioners.

Recently, there are increasingly voices calling for regulation of energy production and use of power sources by using fuel such as gasoline / diesel as a measure to cope with environmental pollution and climate change. As a result, the demand for technology for nuclear energy and alternative energy development is more increased in the energy production part than in the thermal power plant, and the demand for the electric motor with less environmental pollution than the existing gasoline / diesel engine is increasing in terms of the power source.

In the case of an existing automobile that uses fuel, rotational energy is generated in the engine inside the automobile, and power is transmitted to each axle by the gear ratio. However, in the case of using an electric motor instead of the fuel engine, each wheel is easily driven independently, and accordingly, a technology development for a wheel motor in which the wheel itself is a motor is proceeding. Also, there is a great interest in a multi-copter and a drone that can fly using two or more motors as a next generation electric moving body. Multi-copter and drone are also focusing on technology development by electric motor.

In the future, mobile devices are likely to be constructed using electric motors, and electric motors are expected to be implemented using two or more parallel motors. Particularly, in realizing an ultra-high speed / small-sized electric vehicle, a parallel motor driven at a very high speed and a driving method thereof are needed.

It is an object of the present invention to provide a parallel motor system and method of operation thereof that form a maximum torque reserve state in a drive inverter and determine the torque in a DC-DC converter to reduce the loss of switch elements included in the drive inverter.

A method of operating a parallel motor system including motors connected in parallel to a power supply according to an embodiment of the present invention includes forming a maximum torque reserve state in a drive inverter corresponding to each of the motors, Generating a link voltage corresponding to each of the motors based on torque index information including information on each torque and a DC voltage received from the power supply, And operating each of the motors by applying the link voltage, wherein a switching frequency of the switching elements included in the driving inverter is a predetermined value regardless of the torque of each of the motors in the maximum torque reserve state Can be determined.

In an embodiment, the torque index information comprises torque indexes, and each of the torque indexes may include information on the torque of each of the motors.

The generating of the link voltage may include receiving torque index information including information on a torque of each of the motors, generating a torque signal corresponding to each of the motors based on the torque index information, And converting the DC voltage output from the power supply unit to a link voltage corresponding to each of the motors based on the torque signal, wherein the torque signal is configured as a pulse width modulated signal, The torque of each of the motors may be determined according to the duty ratio of the pulse width modulation signal.

As an embodiment, in order to form the maximum torque reserve state, a maximum torque control signal is input to the drive inverter, and the switch elements included in the drive inverter may be turned on or off based on the maximum torque control signal have.

In an embodiment, the maximum torque control signal is not a pulse width modulation signal.

In an embodiment, the maximum torque control signal may be a pulse signal having a constant period.

As an embodiment, the maximum torque reserve state may be defined as a state in which the rotation timing of each of the motors is determined by the maximum torque control signal, and the torque of each of the motors is determined by the link voltage.

A parallel motor system according to another embodiment of the present invention includes motors connected in parallel to a power supply unit, drive inverters that determine the rotation timing of each of the motors based on a maximum torque control signal having a constant frequency, DC converters that receive a DC voltage from the power supply, convert the DC voltage to a link voltage corresponding to each of the motors, and provide the link voltage to each of the drive inverters, Each of the inverters forms a maximum torque reserve state of each of the motors based on the maximum torque control signal, and the torque of each of the motors can be determined by the link voltage.

As an embodiment, the system further includes a converter torque signal generation circuit for receiving the torque index information and generating a torque signal corresponding to each of the motors, wherein the torque index information includes torque indexes for determining the torque of each of the motors can do.

As an embodiment, the converter torque signal generating circuit generates the torque signal as a pulse width modulated signal, and the torque of each of the motors may be determined according to the duty ratio of the pulse width modulated signal.

As an embodiment, the converter torque signal generation circuit includes a converter controller corresponding to each of the motors, and the converter controller is configured to switch the switch elements included in each of the DC-DC converters based on one of the torque indices It is possible to generate switch signals to be controlled.

In an embodiment, the switch signals are pulse width modulated signals complementary to each other.

As an embodiment, it may further comprise an inverter control circuit for receiving a position signal from each of the motors, and for generating the maximum torque control signal based on the position signal.

In one embodiment, the inverter control circuit includes a position detector for receiving a position signal from each of the motors to generate a position information signal, and a controller for controlling the turn-on of the switch elements included in each of the drive inverters Or an inverter controller that generates inverter gate signals to control turn-off.

In an embodiment, the maximum torque control signal is not a pulse width modulation signal.

According to an embodiment of the present invention, the parallel motor system can form a maximum torque reserve state in the drive inverter based on the maximum torque control signal for each motor and determine the torque in the DC-DC converter based on the torque signal. Therefore, the switching frequency of the switch elements included in each drive inverter can be reduced. Also, the loss of the switch elements included in each drive inverter can be reduced.

1 is a block diagram showing a general parallel motor system.
2 is a block diagram illustrating a parallel motor system in accordance with an embodiment of the present invention.
FIG. 3 is a circuit diagram illustrating a DC-DC converter and a drive inverter connected to one motor of FIG. 2; FIG.
4 is an equivalent circuit of the first electric motor of Fig.
5 is a timing diagram showing the first position signal and the corresponding inverter gate signals received from the first motor of FIG.
FIG. 6 is a timing chart showing the converter gate signal applied to the first DC-DC converter of FIG. 3 and the inverter gate signal applied to the first driving inverter of FIG.
7 is a flowchart illustrating an operation method of a parallel motor system according to an embodiment of the present invention.
8 is a block diagram illustrating a parallel motor system according to another embodiment of the present invention.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and should provide a further description of the claimed invention. Reference numerals are shown in detail in the preferred embodiments of the present invention, examples of which are shown in the drawings. Wherever possible, the same reference numbers are used in the description and drawings to refer to the same or like parts.

Hereinafter, a parallel motor system will be used as an example of an apparatus for explaining the features and functions of the present invention. However, those skilled in the art will readily appreciate other advantages and capabilities of the present invention in accordance with the teachings herein. Further, the present invention may be implemented or applied through other embodiments. In addition, the detailed description may be modified or changed in accordance with the aspects and applications without departing substantially from the scope, technical ideas and other objects of the present invention.

1 is a block diagram showing a general parallel motor system. 1, the parallel motor system 10 includes an inverter torque signal generation circuit 11, motor drive circuits 12_1 to 12_n, drive inverters 13_1 to 13_n, and motors 14_1 to 14_n can do. For example, the motor drive circuits 12_1 to 12_n can control the drive inverters 13_1 to 13_n, respectively. The drive inverters 13_1 to 13_n can control the motors 14_1 to 14_n, respectively. The drive inverters 13_1 to 13_n may be connected in parallel to a battery or a power supply device (not shown). That is, each of the drive inverters 13_1 to 13_n may be supplied with the same voltage VDC. Therefore, the electric motors 14_1 to 14_n can be connected in parallel to the battery or the power supply. Hereinafter, the operation of the first electric motor 14_1 will be described as an example.

The inverter torque signal generation circuit 11 can receive the torque index information. The inverter torque signal generation circuit 11 can generate the torque signals TS1 to TSn based on the torque index information. For example, the torque index information may include a plurality of torque information corresponding to each of the motors 14_1 to 14_n. The inverter torque signal generation circuit 11 can generate the torque signals TS1 to TSn respectively corresponding to the motors 14_1 to 14_n based on the torque information corresponding to each of the motors 14_1 to 14_n. Each of the torque signals TS1 to TSn may be a voltage signal having a specific level.

For example, the first electric motor drive circuit 12_1 may receive the first torque signal TS1. Further, the first electric motor drive circuit 12_1 can receive the first position signal HS1 from the first electric motor 14_1. The first motor drive circuit 12_1 can generate the first pulse width modulation signal PWM1 based on the first torque signal TS1 and the first position signal HS1.

Then, the first drive inverter 13_1 can receive the first pulse width modulation signal PWM1. Also, the first drive inverter 13_1 can receive the direct current voltage VDC from the battery or the power supply device. The switching elements of the first driving inverter 13_1 can be switched by the first pulse width modulation signal PWM1. Based on the switching of the switching elements, the first drive inverter 13_1 can generate the first motor drive signal UVW1. The first electric motor 14_1 can rotate based on the first electric motor drive signal UVW1. The second to n-th electric motors 13_2 to 14_n can rotate in the same or similar manner as the first electric motor 14_1.

As a result, each of the drive inverters 13_1 to 13_n may include a plurality of switch elements. Switching elements of each of the drive inverters 13_1 to 13_n can be switched based on the pulse width modulation signal. The pulse width modulation signal for controlling each of the drive inverters 13_1 to 13_n includes information on the torque and the rotation timing of each of the motors. When each motor is driven at a high speed, the switching frequency of the switching elements increases as the speed of the motor increases. Further, since the switching frequency of the switching elements is based on a pulse width modulated signal, the switching frequency of the switching elements can be increased to a greater extent than the speed of the motor. Therefore, in the conventional parallel motor system, the selection of the switching element of the drive inverter is limited.

2 is a block diagram illustrating a parallel motor system in accordance with an embodiment of the present invention. 2, the parallel motor system 100 includes a converter torque signal generation circuit 110, DC-DC converters 121 to 12n, an inverter control circuit 130, drive inverters 141 to 14n, And a plurality of light emitting diodes 151 to 15n. The electric motors 151 to 15n may be connected in parallel to a battery or a power supply unit (not shown). For example, the first DC-DC converter 121 may receive a DC voltage (VDC) from a battery or a power supply. The second DC-DC converter 122 may receive a DC voltage (VDC) from a battery or a power supply. The n-th DC-DC converter 12n can receive the DC voltage VDC from the battery or the power supply. That is, the first to nth motors 151 to 15n respectively connected to the first to nth DC-DC converters 121 to 12n can receive the DC voltage VDC in parallel.

The converter torque signal generation circuit 110 may receive the torque index information and control the torque of the motors 151 to 15n. For example, the torque index information may include torque indexes corresponding to each of the motors 151 to 15n. Each torque index may include information that determines the torque of each electric motor. Converter torque signal generation circuit 110 may generate first to nth torque signals TS1 to TSn based on the torque index information. Each of the torque signals TS1 to TSn may be a pulse width modulated signal. The torques of the electric motors 151 to 15n may be determined according to the duty ratio of the torque signals TS1 to TSn.

The inverter control circuit 130 can receive the position signals HS1 to HSn of the motors 151 to 15n and control the rotation timing of the motors 151 to 15n. For example, the inverter control circuit 130 can detect the current rotational position of the electric motors 151 to 15n based on the position signals HS1 to HSn. The inverter control circuit 130 can generate the maximum torque control signals MTCS1 to MTCSn based on the current rotational position of the detected motors 151 to 15n. The maximum torque control signals MTCS1 to MTCSn may determine the rotation timing of the motors 151 to 15n. Each of the maximum torque control signals MTCS1 to MTCSn may be a pulse signal having a constant period. That is, each of the maximum torque control signals MTCS1 to MTCSn is not a pulse width modulation signal. Thus, each of the drive inverters 141 to 14n can form a state in which the electric motor can operate at the maximum torque (hereinafter referred to as a maximum torque reserve state) based on the maximum torque control signals MTCS1 to MTCSn.

Each of the motors 151 to 15n may be connected to a separate drive inverter and a DC-DC converter. For example, the first electric motor 151 may be connected to the first drive inverter 141 and the first DC-DC converter 121. The second electric motor 152 may be connected to the second drive inverter 142 and the second DC-DC converter 122. The n-th electric motor 15n may be connected to the n-th drive inverter 14n and the n-th DC-DC converter 12n. Each of the motors 151 to 15n may include a brushless DC motor.

Since each of the motors 151 to 15n is connected to a separate drive inverter and a DC-DC converter, the torque and rotation timing of each of the motors 151 to 15n can be independently controlled. For example, the first DC-DC converter 121 may receive the first torque signal TS1 from the converter torque signal generation circuit 110. [ The first torque signal TS1 may include information on the torque of the first electric motor 151. [ The first DC-DC converter 121 can convert the DC voltage VDC into the first DC link voltage VLK1 based on the first torque signal TS1. The first DC link voltage (VLK1) can determine the torque of the first electric motor (151). The first drive inverter 141 may receive the first DC link voltage VLK1 and the first maximum torque control signal MTCS1. The first drive inverter 141 can form the maximum torque reserve state based on the first maximum torque control signal MTCS1. The first drive inverter 141 can generate the first drive signal UVW1 based on the first DC link voltage VLK1 in the maximum torque reserve state. The first electric motor 151 can operate according to the first driving signal UVW1.

In addition, the second DC-DC converter 122 can receive the second torque signal TS2 from the converter torque signal generation circuit 110. [ The second torque signal TS2 may include information on the torque of the second electric motor 152. [ The second DC-DC converter 122 can convert the DC voltage VDC to the second DC link voltage VLK2 based on the second torque signal TS2. And the second DC link voltage VLK2 can determine the torque of the second electric motor 152. [ The second drive inverter 142 may receive the second DC link voltage VLK2 and the second maximum torque control signal MTCS2. The second drive inverter 142 can form the maximum torque reserve state based on the second maximum torque control signal MTCS2. The second drive inverter 142 can generate the second drive signal UVW2 based on the second DC link voltage VLK2 in the maximum torque reserve state. And the second electric motor 152 can operate according to the second driving signal UVW2.

Also, the n-th DC-DC converter 12n can receive the n-th torque signal TSn from the converter torque signal generation circuit 110. [ The n-th torque signal TSn may include information on the torque of the n-th motor 15n. The n-th DC-DC converter 12n can convert the DC voltage VDC into the n-th DC link voltage VLKn based on the n-th torque signal TSn. The n-th DC link voltage VLKn can determine the torque of the n-th motor 15n. The n-th drive inverter 14n may receive the n-th DC link voltage VLKn and the n-th maximum torque control signal MTCSn. The n-th drive inverter 14n can form the maximum torque reserve state based on the n-th maximum torque control signal MTCSn. The n-th drive inverter 14n may generate the n-th drive signal UVWn based on the n-th DC link voltage VLKn in the maximum torque reserve state. The n-th motor 15n may operate according to the n-th driving signal UVWn.

The parallel motor system 100 according to an embodiment of the present invention may include a DC-DC converter and a drive inverter connected to the respective motors. For example, a dc-to-dc converter can determine the torque of the motor. The drive inverter can determine the rotation timing of the electric motor. The drive inverter forms the maximum torque reserve state based on the maximum torque control signal and the pulse width modulation signal does not need to be input to the switch elements of the drive inverter since the DC to DC converter determines the torque. That is, the parallel motor system 100 according to the embodiment of the present invention can prevent the switching frequency of the switching elements of the driving inverter from rapidly increasing during the high-speed operation. Accordingly, the parallel motor system 100 according to the embodiment of the present invention can reduce the loss of the switching elements of the drive inverter in high-speed operation.

FIG. 3 is a circuit diagram illustrating a DC-DC converter and a drive inverter connected to one motor of FIG. 2; FIG. Referring to FIG. 3, the first electric motor 151 may be connected to the first DC-DC converter 121 and the first drive inverter 141. The other DC-DC converters 122 to 12n and the drive inverters 142 to 14n in FIG. 2 have the same or similar structure as the first DC-DC converter 121 and the first drive inverter 141 in FIG. 3 Lt; / RTI > In addition, the other electric motors 152 to 15n in Fig. 2 can operate in the same or similar manner as the first electric motor 151 in Fig.

The first DC-DC converter 121 can receive the DC voltage VDC. The first DC-DC converter 121 can operate based on the converter gate signals SA, SB. For example, the first DC-DC converter 121 may include two switch elements S1 and S2, an inductor L1 and a capacitor C1. The switch elements S1 and S2 may be turned on or off based on the converter gate signals SA and SB. The switch elements S1 and S2 may be turned on or off complementarily with each other. The converter gate signals SA, SB correspond to the first torque signal TS1 of Fig. The converter gate signals SA, SB may be pulse width modulated signals. Thus, the pulse width of the converter gate signals SA, SB can be adjusted based on the first torque index. The DC voltage VDC will be modulated in pulse width by the switch elements S1 and S2 to form the voltage at the node N1. The inductor L1 can rectify the voltage at the node N1 to form the voltage at the node N2. The capacitor C1 may generate the first link voltage VLK1 between the node N2 and the node N3. As a result, the first link voltage VLK1 can determine the torque of the first electric motor 151 based on the first torque index.

The converter torque signal generation circuit 110 may include a plurality of converter controllers. For example, the converter torque signal generation circuit 110 may include converter controllers corresponding to each of the DC-DC converters 121 to 12n in FIG. However, for convenience of explanation, only the first converter controller 111 is shown in Fig. The first converter controller 111 may receive the first torque index. The first torque index may be included in the torque index information of FIG. The torque index information of FIG. 2 may include torque indexes corresponding to each of the DC-DC converters 121 to 12n. The first converter controller 111 may generate converter gate signals SA, SB based on the first torque index. The first torque index may include information on the torque of the first electric motor 151. [

Further, the first converter controller 111 can detect the voltage V_N2 of the node N2. The first converter controller 111 can continuously monitor the voltage V_N2 of the detected node N2. The first converter controller 111 can continuously control the converter gate signals SA and SB so that the voltage V_N2 of the node N2 has a value corresponding to the first torque index.

The first drive inverter 141 can receive the first link voltage VLK1. The first drive inverter 141 may operate based on the inverter gate signals UH, UL, VH, VL, WH, WL. For example, the first drive inverter 141 may include the switch elements Q1 to Q6 and the unidirectional elements D1 to D6. The first drive inverter 141 may be a six-step inverter. The switch elements Q1 to Q6 may be sequentially turned on or off based on the inverter gate signals UH, UL, VH, VL, WH, and WL. Depending on the turn-on or turn-off of the switch elements Q1 to Q6, the direction of the current flowing through the terminals U, V and W can be determined. Thereby, the first electric motor 151 can operate. The switching elements Q1 to Q6 may be field-effect transistors. However, the types of the switching elements Q1 to Q6 are not limited to this. The unidirectional elements D1 to D6 can prevent the erroneous current from flowing to the switch elements Q1 to Q6.

The inverter control circuit 130 may include a plurality of position detectors and a plurality of inverter controllers. For example, the inverter control circuit 130 may include a position detector and an inverter controller corresponding to each of the drive inverters 141 to 14n in Fig. However, for convenience of explanation, only the first position detector 131_1 and the first inverter controller 131_2 corresponding to the first drive inverter 141 are shown in FIG. The first position detector 131_1 may receive the hall sensor signals Ha, Hb, and Hc from the first electric motor 151. [ The Hall sensor signals Ha, Hb, Hc correspond to the first position signal HS1 in Fig. The first position detector 131_1 can generate the position information signal PIS based on the hall sensor signals Ha, Hb, and Hc. The first inverter controller 131_2 may generate the inverter gate signals UH, UL, VH, VL, WH, WL based on the position information signal PIS. The inverter gate signals UH, UL, VH, VL, WH, and WL may be pulse signals having a constant period. The inverter gate signals (UH, UL, VH, VL, WH, WL) are not pulse width modulated signals. The inverter gate signals UH, UL, VH, VL, WH, and WL correspond to the first maximum torque control signal MTCS1 of FIG. The maximum torque of the first electric motor 151 can be determined by the inverter gate signals UH, UL, VH, VL, WH, and WL.

According to the embodiment of the present invention, the first inverter controller 131_2 outputs the inverter gate signals UH, UL, VH, VL, WH, WL, which are not pulse width modulation signals, as the maximum torque control signal to the first drive inverter 141 to the switch elements Q1 to Q6. The first drive inverter 141 may form a maximum torque reserve state based on the inverter gate signals UH, UL, VH, VL, WH, WL. At this time, the first converter controller 111 can supply the converter gate signals SA and SB, which are pulse width modulation signals, as a torque signal to the first DC-DC converter 121 to determine the first link voltage VLK1 have. That is, the torque of the first electric motor 151 can be determined by the first link voltage VLK1. Therefore, in the high-speed operation, the switching frequency of the switching elements Q1 to Q6 included in the first driving inverter 141 may be lower than the switching frequency of the switching elements included in the first driving inverter 13_1 have. That is, the parallel motor system 100 of the present invention can reduce the switching frequency of the switch elements included in the drive inverter by the DC-DC converter determining the torque of the motor.

4 is an equivalent circuit of the first electric motor of Fig. Referring to FIG. 4, the first electric motor 151 may include coils ML1, ML2, and ML3 connected between a motor center MO and each of the terminals U, V, and W. For example, the first electric motor 151 may be a three-phase electric motor. The first electric motor 151 may be a brushless direct current (BLDC) electric motor. The first electric motor 151 may include a rotor made of a permanent magnet. The rotor can rotate according to the magnetic field formed in the coils ML1, ML2, and ML3 included in the first electric motor 151. [ The magnetic field formed in the coils ML1, ML2 and ML3 can be determined according to the directions (① to ⑥) of the currents flowing through the coils ML1, ML2 and ML3. The other electric motors 152 to 15n of FIG. 2 may have the same or similar structure as the first electric motor 151 of FIG.

5 is a timing diagram showing the first position signal and the corresponding inverter gate signals received from the first motor of FIG. 3 to 5, based on the first position signal HS1 received from the first electric motor 151, the first inverter controller 131_2 generates inverter gate signals UH, UL, VH , VL, WH, WL). Based on the inverter gate signals (UH, UL, VH, VL, WH, WL), the rotation timing of the first electric motor 151 can be determined.

For example, the first position signal HS1 may include hall sensor signals Ha, Hb, Hc. The hall sensor signals Ha, Hb and Hc may be mounted on the first electric motor 151 at intervals of 120 degrees. The first position detector 131_1 may combine the Hall sensor signals Ha, Hb and Hc to predict the position of the current rotor. However, the method of determining the position of the rotor is not limited to this. When the position of the rotor is determined, the first inverter controller 131_2 outputs the inverter gate signals UH, UL, VH, VL, WH, WL based on the position information signal PIS including the position of the rotor Can be generated. Based on the inverter gate signals UH, UL, VH, VL, WH and WL, the switch elements Q1 to Q6 included in the first drive inverter 141 can be turned on or off.

In the first process (1) between the time point t1 and the time point t2, the first switch element Q1 and the fourth switch element Q4 will be turned on. And the remaining switch elements Q2, Q3, Q5 and Q6 will be turned off. Thus, the current will flow from terminal U to terminal V. [

In the second process (2) between the time point t2 and the time point t3, the first switch element Q1 and the sixth switch element Q6 will be turned on. And the remaining switch elements Q2, Q3, Q4 and Q5 will be turned off. Thus, the current will flow from the terminal U to the terminal W. [

In the third process (3) between the time point t3 and the time point t4, the third switch element Q3 and the sixth switch element Q6 will be turned on. And the remaining switch elements Q1, Q1, Q4 and Q5 will be turned off. Therefore, the current will flow from the terminal V to the terminal W. [

In the fourth step (4) between the time point t4 and the time point t5, the second switch element Q2 and the third switch element Q3 will be turned on. And the remaining switch elements Q1, Q4, Q5 and Q6 will be turned off. Thus, the current will flow from terminal V to terminal U.

In the fifth step (5) between the time point t5 and the time point t6, the second switch element Q2 and the fifth switch element Q5 will be turned on. And the remaining switch elements Q1, Q3, Q4 and Q6 will be turned off. Thus, the current will flow from the terminal W to the terminal U.

In the sixth step (6) between the time point t6 and the time point t7, the fourth switch element Q4 and the fifth switch element Q5 will be turned on. And the remaining switch elements Q1, Q2, Q3 and Q6 will be turned off. Thus, the current will flow from the terminal W to the terminal V. [

When the first to sixth steps (1) to (6) are performed once, the rotor of the first electric motor 151 can make one rotation. In order to continuously rotate the rotor of the first electric motor 151, the first to sixth processes (1 to 6) are repeatedly performed based on the inverter gate signals UH, UL, VH, VL, . In this process, the inverter gate signals UH, UL, VH, VL, WH, and WL may be generated as a pulse signal having a constant period rather than a pulse width modulation signal. Therefore, the first drive inverter 141 can form the maximum torque reserve state for the first electric motor 151 based on the inverter gate signals UH, UL, VH, VL, WH, and WL.

FIG. 6 is a timing chart showing the converter gate signal applied to the first DC-DC converter of FIG. 3 and the inverter gate signal applied to the first driving inverter of FIG. 3 to 6, the first DC-DC converter 121 controls the torque of the first electric motor 151 and the first drive inverter 141 controls the torque of the first electric motor 151 in the maximum torque reserve state Can be formed.

5, the first drive inverter 141 drives the first drive inverter 141 based on the inverter gate signals UH, UL, VH, VL, WH, and WL through the first through sixth processes A maximum torque reserve state can be formed. At this time, the first DC-DC converter 121 may generate the first link voltage VLK1 based on the converter gate signals SA, SB.

For example, the converter gate signals SA, SB may be a pulse width modulated signal whose pulse width is adjusted according to the first torque index. The converter gate signals SA and SB may be complementary to each other. The first link voltage VLK1 may be determined according to the duty ratio of the converter gate signals SA, SB. 6, the duty ratio of converter gate signals SA, SB increases until time t4. The first link voltage VLK1 may increase with the converter gate signals SA, SB up to a time point t4. In addition, the duty ratio of the converter gate signals SA, SB decreases after the time t5. The first link voltage VLK1 may decrease in accordance with the converter gate signals SA and SB after the time point t5. However, this is an example, and the first link voltage VLK1 may be variously determined according to the duty ratio of the converter gate signals SA and SB. Therefore, the torque of the first electric motor 151 can be determined according to the duty ratio of the converter gate signals SA, SB.

As a result, the torque of the first electric motor 151 is determined by the first DC-DC converter 121, and the first inverter controller 131_2 outputs the inverter gate signals UH, UL, VH VL, WH, WL) to the switch elements Q1 to Q6 of the first drive inverter 141 as the maximum torque control signal. Therefore, in the high-speed operation, the switching frequency of the switching elements Q1 to Q6 included in the first driving inverter 141 may be lower than the switching frequency of the switching elements included in the first driving inverter 13_1 have. That is, the parallel motor system 100 of the present invention can reduce the switching frequency of the switch elements included in the drive inverter by the DC-DC converter determining the torque of the motor.

7 is a flowchart illustrating an operation method of a parallel motor system according to an embodiment of the present invention. Referring to FIGS. 2 and 7, the parallel motor system 100 may receive a direct current voltage (VDC) from a battery or a power supply (not shown). The electric motors 151 to 15n may be connected in parallel to the direct current voltage VDC.

In step S110, the parallel motor system 100 may receive the torque index information. For example, the converter torque signal generation circuit 110 may receive torque index information including torque indexes corresponding to each of the motors 151 to 15n. In step S120, the parallel motor system 100 may generate the torque signals TS1 to TSn corresponding to the respective motors 151 to 15n based on the torque index information. For example, each of the torque signals TS1 to TSn may be a pulse width modulated signal. In step S130, the parallel motor system 100 may receive a direct voltage (VDC) from a battery or a power supply. For example, each of the DC-DC converters 121 to 12n can commonly receive the DC voltage VDC. That is, the DC-DC converters 121 to 12n may be connected in parallel to the battery or the power supply.

In step S140, the parallel motor system 100 sets the DC voltage VDC based on the torque signal in the DC-DC converter corresponding to each of the motors 151 to 15n to the link corresponding to each of the motors 151 to 15n, Voltage. For example, the first DC-DC converter 121 can convert the DC voltage VDC into the first link voltage VLK1 based on the first torque signal TS1. The second DC-DC converter 122 may convert the DC voltage VDC to the second link voltage VLK2 based on the second torque signal TS2. The n-th DC-DC converter 12n can convert the DC voltage VDC to the n-th link voltage VLKn based on the n-th torque signal TSn.

In step S150, the parallel motor system 100 may form the maximum torque reserve state based on the maximum torque control signal in the drive inverter corresponding to each of the motors 151 to 15n. For example, the first drive inverter 141 can form the maximum torque reserve state based on the first maximum torque control signal MTCS1. The second drive inverter 142 can form the maximum torque reserve state based on the second maximum torque control signal MTCS2. The n-th drive inverter 14n can form the maximum torque reserve state based on the n-th maximum torque control signal MTCSn. The maximum torque reserve state means that the drive inverter determines the rotation timing of the electric motor and the torque of the electric motor is determined according to the input link voltage. Each of the maximum torque control signals MTCS1 to MTCSn may include inverter gate signals having a constant period. The inverter gate signals can turn on or off the switch elements included in each of the drive inverters 141 to 14n. In addition, inverter gate signals are not pulse width modulated signals.

In step S160, the parallel motor system 100 can generate drive signals corresponding to each of the motors 151 to 15n by the drive inverter based on the link voltage in the maximum torque reserve state. For example, the first drive inverter 141 may generate the first drive signal UVW1 based on the first link voltage VLK1 and the first maximum torque control signal MTCS1. The second drive inverter 142 may generate the second drive signal UVW2 based on the second link voltage VLK2 and the second maximum torque control signal MTCS2. The n-th drive inverter 14n may generate the n-th drive signal UVWn based on the n-th link voltage VLKn and the n-th maximum torque control signal MTCSn.

In step S170, the parallel motor system 100 can operate each of the motors 151 to 15n based on the drive signal. For example, the progress path of each of the drive signals UVW1 to UVWn is changed in the motors 151 to 15n according to the turn-on or turn-off operation of the switch elements included in each of the drive inverters 141 to 14n . A magnetic field is formed inside the electric motors 151 to 15n along the traveling path of each of the driving signals UVW1 to UVWn and the rotor of each of the electric motors 151 to 15n can rotate according to the formed magnetic field.

As described above, the parallel motor system 100 according to the embodiment of the present invention may include a DC-DC converter and a drive inverter connected to the respective motors. For example, a dc-to-dc converter can determine the torque of the motor. The drive inverter can determine the rotation timing of the electric motor. The drive inverter forms the maximum torque reserve state based on the maximum torque control signal and the pulse width modulation signal does not need to be input to the switch elements of the drive inverter since the DC to DC converter determines the torque. That is, the parallel motor system 100 according to the embodiment of the present invention can prevent the switching frequency of the switching elements of the driving inverter from rapidly increasing during the high-speed operation. Accordingly, the parallel motor system 100 according to the embodiment of the present invention can reduce the loss of the switching elements of the drive inverter in high-speed operation.

8 is a block diagram illustrating a parallel motor system according to another embodiment of the present invention. Referring to FIG. 8, the parallel motor system 200 may use one single inductor multi-output converter 220, unlike the parallel motor system 100 of FIG. The parallel motor system 200 may include the same or similar configurations as the parallel motor system 100 of FIG. Therefore, the difference between the parallel motor system 200 and the parallel motor system 100 of FIG. 2 will be described below.

The parallel motor system 100 of FIG. 2 uses independent DC-DC converters 121 to 12n for each of the motors 151 to 15n. Each of the DC-DC converters 121 to 12n includes an inverter. Therefore, the area by a plurality of inverters can not be ignored. On the other hand, the parallel motor system 200 can use a single inductor multi-output converter 220. The single inductor multi-output converter 220 may include only one inductor 221 therein. Thus, the parallel motor system 200 can reduce its area compared to the parallel motor system 100 of FIG.

Converter torque signal generation circuit 210 may receive torque index information. For example, the converter torque signal generation circuit 210 can generate one common torque signal TS based on the torque index information. The single inductor multi-output converter 220 can convert the DC voltage VDC to the link voltages VLK1 to VLKn based on the torque signal TS. The link voltages VLK1 to VLKn may be the same or similar to each other. Therefore, the torques of the electric motors 251 to 25n can be determined equally or similarly.

The embodiments have been disclosed in the drawings and specification as described above. Although specific terms have been employed herein, they are used for purposes of illustration only and are not intended to limit the scope of the invention as defined in the claims or the claims. Therefore, those skilled in the art will appreciate that various modifications and equivalent embodiments are possible without departing from the scope of the present invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10, 100, 200: Parallel motor system
11: Inverter torque signal generation circuit
12_1 to 12_n: first to nth motor drive circuits
13_1 to 13_n, 141 to 14n, and 241 to 24n: the first to n-
14_1 to 14_n, 151 to 15n, and 251 to 25n: first to nth electric motors
110, 210: converter torque signal generation circuit
121 to 12n: first to n-th DC-DC converters
130, 230: inverter control circuit
220: Single Inductor Multi-Output Converter

Claims (15)

A method of operating a parallel motor system including motors connected in parallel to a power supply, the method comprising:
Forming a maximum torque reserve state in a drive inverter corresponding to each of the motors;
Generating a link voltage corresponding to each of the motors based on torque index information including information on a torque of each of the motors and a DC voltage received from the power supply; And
Operating each of the motors by applying the link voltage to the drive inverter in the maximum torque reserve state,
Wherein the switching frequency of the switching elements included in the drive inverter is determined to be a specific value regardless of the torque of each of the motors in the maximum torque reserve state. The method according to claim 1,
Wherein the torque index information comprises torque indexes,
Each of the torque indices including information about a torque of each of the motors. The method according to claim 1,
Wherein generating the link voltage comprises:
Receiving torque index information including information on a torque of each of the motors;
Generating a torque signal corresponding to each of the electric motors based on the torque index information; And
And converting the DC voltage output from the power supply unit into a link voltage corresponding to each of the motors based on the torque signal,
The torque signal is configured as a pulse width modulated signal,
Wherein a torque of each of the motors is determined according to a duty ratio of the pulse width modulated signal. The method according to claim 1,
In order to form the maximum torque reserve state, a maximum torque control signal is input to the drive inverter,
Wherein the switch elements included in the drive inverter are turned on or off based on the maximum torque control signal. 5. The method of claim 4,
Wherein the maximum torque control signal is not a pulse width modulated signal. 5. The method of claim 4,
Wherein the maximum torque control signal is a pulse signal having a constant period. The method according to claim 1,
Wherein the maximum torque reserve state is defined as a state in which the rotation timing of each of the motors is determined by the maximum torque control signal and the torque of each of the motors is determined by the link voltage. Motors connected in parallel to the power supply;
Drive inverters for determining a rotation timing of each of the electric motors based on a maximum torque control signal having a constant frequency; And
DC converters that receive DC voltage from the power supply, convert the DC voltage to a link voltage corresponding to each of the motors, and provide the link voltage to each of the drive inverters,
Each of the drive inverters forms a maximum torque reserve state of each of the motors based on the maximum torque control signal,
Wherein the torque of each of the motors is determined by the link voltage. 9. The method of claim 8,
Further comprising a converter control circuit that receives the torque index information and generates a torque signal corresponding to each of the motors,
Wherein the torque index information comprises torque indices that determine the torque of each of the motors. 10. The method of claim 9,
The converter control circuit generates the torque signal as a pulse width modulated signal,
Wherein the torque of each of the motors is determined in accordance with the duty ratio of the pulse width modulated signal. 10. The method of claim 9,
Wherein the converter control circuit includes a converter controller corresponding to each of the motors,
Wherein the converter controller generates switch signals that control switch elements included in each of the DC-DC converters based on one of the torque indices. 12. The method of claim 11,
Wherein the switch signals are pulse width modulated signals complementary to each other. 9. The method of claim 8,
Further comprising an inverter control circuit for receiving a position signal from each of the motors and generating the maximum torque control signal based on the position signal. 14. The method of claim 13,
The inverter control circuit includes:
A position detector for receiving a position signal from each of the motors and generating a position information signal; And
And an inverter controller for generating inverter gate signals for controlling turn-on or turn-off of the switch elements included in each of the drive inverters based on the position information signal. 9. The method of claim 8,
Wherein the maximum torque control signal is not a pulse width modulated signal.

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