KR20120039822A - Motor driving inverter for reducing electromagnetic noise and motor drive apparatus using the same - Google Patents

Abstract

PURPOSE: A motor driving inverter and a motor driving apparatus using the same are provided to prevent malfunction due to electromagnetic interference by reducing electromagnetic noise according to a high-speed switching operation of a power switching semiconductor device. CONSTITUTION: A switching device outputs driving voltage through an output connection point. A first capacitor performs a first electromagnetic noise reduction process by arranging an X-cap. A snubber circuit performs a second electromagnetic noise reduction process. The snubber circuit connects a resistor and a second capacitor in series. A third capacitor forms a Y-cap.

Description

Motor-driven inverter that reduces electromagnetic noise and motor-driven device using the same {MOTOR DRIVING INVERTER FOR REDUCING ELECTROMAGNETIC NOISE AND MOTOR DRIVE APPARATUS USING THE SAME}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor drive inverter for reducing electromagnetic noise and a motor drive device using the same. More particularly, the present invention relates to a radio frequency band (especially AM and FM frequency bands) generated from an inverter in an automobile motor drive device. In order to reduce electromagnetic noise intensively, RC snubber circuits are inserted in each switching element based on a capacitor forming an X-cap connected to both ends of the power supply to reduce the frequency of the radio frequency band, and additionally, U, V, W phase The present invention relates to a motor drive inverter for reducing electromagnetic noise and a motor driving apparatus using the same for connecting a capacitor forming a Y-cap to an output connection point to reduce electromagnetic noise in a high frequency region.

In recent years, brushless DC motors have a current-to-torque, speed-to-voltage characteristic similar to that of DC motors in synchronous motor structures, and have high efficiency and high power density from home appliances to industrial equipment. The field of application is increasing.

Brushless DC motors are also referred to as commutatorless motors, and are usually switched by power switching semiconductor devices (e.g. transistors, FETs, IGBTs, etc.) that make up the inverter instead of brushes and commutators, which are important parts of the DC motor. It drives by generating torque by switching the current flowing through the stator windings. These brushless DC motors are mainly driven in three phases (U-phase, W-phase, V-phase), which makes torque control easier, higher efficiency, and less noise than single phase.

The brushless direct current motor arranges a stator winding three coils electrically with a phase difference of 120 degrees to face a rotor with permanent magnets, and selectively supplies power to the coils of each phase through a switching element. As the rotor is applied, the rotor is rotated by a magnetic force acting between the stator core and the permanent magnet being magnetized. At this time, the brushless DC motor detects the relative position between the rotor and the stator to control the driving. For this purpose, the brushless DC motor stator is based on the position information between the rotor and the stator, which is confirmed from a position recognition device such as a Hall sensor through an inverter. Apply the appropriate voltage to the coil.

Generally, the motor drive device required to drive a brushless DC motor includes a voltage inverter using six power switching semiconductor elements. In this case, the inverter is mainly controlled according to a pulse width modulation (PWM) scheme. The pulse width modulation method is a method of controlling an average current by applying a current in a pulse method while maintaining a constant voltage, and controlling a ratio of pulse widths.

As described above, the inverter of the motor driving apparatus performs a pulse width modulation method by high speed switching (ON / OFF) of the power switching semiconductor element to control the motor in a three-phase driving method. In this case, the inverter causes electromagnetic noise having a frequency band of several tens of MHz according to the fast switching operation due to the characteristics of the power switching semiconductor device. The electromagnetic noise has a characteristic of increasing as the rate of change of the voltage (or current) increases during the switching operation of the power switching semiconductor device.

Accordingly, in the related art, at least one capacitor is connected to both ends of a power supply of an inverter circuit, thereby reducing back EMF due to a switching operation of a power switching semiconductor element, and bypassing the generated electromagnetic noise to the outside. Emission to induce electromagnetic noise reduction as a whole. This can be applied in a general way of reducing electromagnetic noise when the overall width of the electromagnetic noise is not large in the inverter circuit of the motor driving device. However, when the width of the electromagnetic noise is large, a specific frequency band [particularly, a radio frequency band- , AM frequency band (520 kHz to 1.8 MHz) and FM frequency band (78 MHz to 108 MHz), and electromagnetic noise was not reduced to meet the desired regulatory standards.

Electromagnetic noise generated from the inverter of the motor drive device affects peripheral electronic devices and causes disturbances in the performance of the electronic devices. Furthermore, in automobiles, it is possible to anticipate damage to life and property due to malfunction of the electronic device when the electromagnetic noise generated from the inverter of the motor driving device is not suppressed. For example, a sudden start of a vehicle is known as a representative case due to malfunction of the electronic device. In other words, the rapid start phenomenon is a sudden acceleration due to the rapid increase in the rotational speed of the engine at the start of an automatic transmission vehicle or after the start of a stop. have. For the above reasons, the automotive industry has strictly applied electromagnetic noise regulation standards to automobiles.

BACKGROUND ART Recently, various devices that were operated in a mechanical manner due to the development of electronic control technology are driven in an electric manner due to driver convenience and driving safety.

For example, a recent automobile has a transmission control unit (TCU) that changes the driving speed and torque of the vehicle according to the driving conditions of the vehicle, and the vehicle according to various driving information of the driving vehicle in addition to the driver's brake pedal operation. Anti-lock Braking System (ABS) and Gasoline Direct Injector (GDI) engines for throttle An electronic throttle controller (ETC) for controlling the electric power is driven in an electrical control scheme. At this time, the electronic control devices such as TCU, ABS, ETC, etc., can communicate with the engine control unit (ECU) through the CAN (Controller Area Neteork (CAN)) communication scheme to receive the driving information of the vehicle. Here, the can communication scheme represents a vehicle network system for providing digital serial communication between electronic control devices of a vehicle by a high communication line and a low communication line.

As described above, the engine control unit ECU cannot be free from electromagnetic interference in that it controls electronic control devices such as TCU, ABS, ETC, and the like through electrical communication by can communication. In particular, since the can communication system is very vulnerable to electromagnetic noise in the FM frequency band of 88 MHz to 108 MHz, it is necessary to design a vehicle so as to intensively block the electromagnetic noise in the FM frequency band. That is, since the automobile is closely related to the driver's life, the possibility of malfunction due to electromagnetic interference should be prevented in advance so as to ensure the driver's safety.

In addition, the automobile should reduce the electromagnetic noise generated from the inverter to provide the driver's radio listening environment to provide a comfortable environment for the driver listening to the radio frequency band without the influence of electromagnetic noise.

For this reason, the inverter of the motor driving device mainly reduces electromagnetic noise (especially electromagnetic noise in the radio frequency band) due to the high-speed switching operation of the power switching semiconductor element, thereby preventing malfunction of the automotive electronic device due to electromagnetic interference. Rather, it is necessary to provide the driver with a comfortable radio listening environment.

Therefore, the prior art as described above needs to manage the electromagnetic wave noise of the radio frequency band affecting the electronic device in the automobile, but there is a problem that it is difficult to reduce the electromagnetic wave noise of the radio frequency band below a predetermined level. It is an object of the present invention to solve the problem.

Therefore, the present invention is based on a capacitor to form an X-cap connected to both ends of the power source in order to intensively reduce the electromagnetic noise of the radio frequency band (especially AM and FM frequency band) generated from the inverter in the motor drive device for automobiles Insertion of RC snubber circuit into each switching element reduces the frequency of radio frequency band and additionally connects capacitors forming Y-cap to output connection points on U, V, W to reduce electromagnetic noise in high frequency region. Another object is to provide a motor driving inverter for reducing electromagnetic noise and a motor driving device using the same.

The objects of the present invention are not limited to the above-mentioned objects, and other objects and advantages of the present invention which are not mentioned can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

In order to achieve the above object, the present invention is a motor drive inverter of a vehicle, including at least one drive circuit for providing a driving voltage according to the phase, the drive circuit, the upper and lower interconnection to the totem pole structure A pair of switching elements for outputting a driving voltage through the output connection point; A first capacitor disposed at both ends of the power supply of the pair of switching elements to form an X-cap to primarily reduce electromagnetic noise; And a snubber circuit connected in parallel between the drain and the source of each of the pair of switching elements to reduce the electromagnetic noise secondarily based on the electromagnetic noise level reduced by the first capacitor.

The snubber circuit is formed by connecting a resistor and a second capacitor in series.

The driving circuit is characterized in that it reduces electromagnetic noise of AM frequency band and FM frequency band which are radio frequency bands.

The driving circuit may include a third capacitor connected between the output connection point of the pair of switching elements and the ground to form a Y-cap for reducing electromagnetic noise of a high frequency band.

On the other hand, the present invention is a motor drive device, including a microcomputer, logic unit, gate driver unit, inverter and motor, wherein the inverter, three drive circuits to provide a three-phase drive voltage of the U phase, V phase, W phase The furnace circuit is connected in parallel, and the driving circuit includes a pair of switching elements for outputting a driving voltage through an output connection point interconnected in a totem pole structure at an upper portion and a lower portion; A first capacitor disposed at both ends of the power supply of the pair of switching elements to form an X-cap to primarily reduce electromagnetic noise; And a snubber circuit connected in parallel between the drain and the source of each of the pair of switching elements to secondly reduce the electromagnetic noise based on the electromagnetic noise level reduced by the first capacitor.

As described above, the present invention is to effectively reduce the electromagnetic noise (especially the electromagnetic wave noise of the radio frequency band) due to the high-speed switching operation of the power switching semiconductor device to prevent the malfunction of the automotive electronic device due to electromagnetic interference There is.

In addition, the present invention has the effect of providing a driver with a radio listening environment is reduced the effect of electromagnetic noise.

In particular, the present invention has the effect of reducing electromagnetic noise in a radio frequency band-that is, in the AM frequency band (520 Hz to 1.8 MHz) and the FM frequency band (78 MHz to 108 MHz) so as to meet desired regulatory standards. .

In addition, the present invention is provided with a Y-cap at the output connection point of the U-phase, V-phase, W-phase has the effect of removing the electromagnetic noise of the high frequency band.

1 is a block diagram of a motor driving apparatus according to an embodiment of the present invention,
2 is a circuit diagram of an inverter according to the present invention;
3A and 3B are graphs illustrating a change in driving voltage with time of on / off switching device by a snubber circuit;
4A and 4B are graphs showing electromagnetic noise reduction for snubber circuits,
5a to 5c are graphs showing electromagnetic noise reduction for an FM frequency band;
6A and 6B are graphs showing electromagnetic noise reduction by Y-cap.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings, It can be easily carried out. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail. Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a motor driving apparatus according to an embodiment of the present invention.

The motor driving apparatus shown in FIG. 1 includes a microcomputer 10, a logic unit 20, a gate driver unit 30, and an inverter 40 to apply driving power to the motor 50. At this time, the motor driving device is an example of driving the motor 50 in a three-phase driving method, three pairs of power switching semiconductor elements, that is, three upper switching units (that is, the first switching unit 41H, first) 3 switching section 42H, fifth switching section 43H] and three lower switching sections (ie, second switching section 41L, fourth switching section 42L, and sixth switching section 43L). By forming the inverter 40 in a totem pole structure for three phases of the U phase, V phase, and W phase, the motor 50 is generated by generating the inverter output from the output connection points P _U , P _V , P _{W of} each phase. 3 phase driving voltages (ie, OUT1, OUT2, and OUT3) are alternately applied to the three-phase driving coils.

Here, the upper switching parts 41H, 42H, 43H and the lower switching parts 41L, 42L, 43L will be described in the case where 'FET' is applied as an example of the power switching semiconductor device, but is not limited thereto.

In addition, in the case of applying the FET as the power switching semiconductor element, the upper switching portions 41H, 42H, 43H use P channel elements and the lower switching portions 41L, 42L, 43L use N channel elements. Although the driving circuits can be easily combined, since the P-channel device is 1.5 to 2.5 times more expensive than the N-channel device, the N-channel device is generally used even in the case of the upper switching parts 41H, 42H, and 43H.

Hereinafter, the component of a motor drive apparatus is demonstrated.

First, the microcomputer 10 outputs the pulse width modulation signal PWM to the logic unit 20.

Next, the logic unit 20 outputs the pulse width modulation signal output from the microcomputer 10 and three detection signals HS at which the position recognition device (hall sensor, etc.) of the motor 50 detects the magnet polarity of the rotor. Are combined to form gate control signals HIN and LIN. At this time, the logic unit 20 outputs the gate control signals HIN and LIN to each of the first gate driver 31 to the third gate driver 33. Alternatively, the logic unit 20 may output a pulse output from the microcomputer 10 by combining the detection signal HS and the original motor driving command with the magnet polarity of the rotor recognized by the position recognition device (hall sensor, etc.) of the motor 50. The width modulation signal PWM may be input, and the gate control signals HIN and LIN may be output to each of the first gate driver 31 to the third gate driver 33.

Next, the gate driver 30 transmits the gate control signals HIN and LIN output from the logic unit 20 to the upper switching units 41H, 42H and 43H and the lower switching units 41L and 42L of the inverter 40. To the driver signals UH-UL, VH-VL, and WH-WL capable of driving 43L, respectively, so that the upper and lower switching portions 41H, 42H, 43H and 41L, 42L, 43L Applied to the gate terminal.

Next, the inverter 40 includes a motor to which each output connection point P _U , P _V , P _W between the upper switching parts 41H, 42H, 43H and the lower switching parts 41L, 42L, 43L corresponds, respectively. Each output connection point P _U , P _V connected to the three-phase driving coil of 50, in accordance with each driver signal UH-UL, VH-VL, WH-WL sequentially or selectively applied to the gate terminal. , P _W ) outputs the three-phase driving voltage to the motor 50.

Briefly, operations of the upper switching parts 41H, 42H, 43H and the lower switching parts 41L, 42L, 43L will be described. First, assuming that the first switching unit 41H is turned on at the top, the second switching unit 41L is set to the turn-off state at the lower portion corresponding to the first switching unit 41H. Thus, when a high level signal is applied to the gate of the first switching unit 41H and turned on, the motor driving current flows from the output connection point P _U to the U-phase coil 51 through the first switching unit 41H. . At this time, the U-phase driving voltage is applied to the motor 50. The motor driving current flowing to the U-phase coil 51 is grounded through one of the V-phase coil 52 and the W-phase coil 53 by turning on one of the fourth switching portion 42L and the sixth switching portion 43L. Flows into. Similarly, the same applies to the case where the first switching unit 41H is turned on even when the third switching unit 42H or the fifth switching unit 43H is turned on.

Next, the motor 50 is provided with a U-phase coil 51, a V-phase coil 52, and a W-phase coil 53 on the stator so that driving is performed in a three-phase driving method. BLDC motor connected by

Hereinafter, the structure of the inverter 40 will be described in detail with reference to FIG. 2.

FIG. 2 is a circuit diagram of an inverter according to the present invention, and FIGS. 3A and 3B are graphs illustrating a change in driving voltage with time of switching on and off of a switching device by a snubber circuit.

As shown in FIG. 2, the inverter 40 according to the present invention generates a three-phase driving voltage, that is, a U-phase driving voltage OUT1, a V-phase driving voltage OUT2, and a W-phase driving voltage OUT3, respectively. In order to sequentially output the drive circuit of the same structure for output to the coils (51, 52, 53) of the motor 50 in parallel. At this time, the upper end of each driving circuit is connected to each other, the power supply voltage (VDD) is commonly applied, the lower end is connected to each other and grounded.

For convenience of description, the driving circuit for outputting the U-phase driving voltage OUT1 is referred to as the "U-phase driving circuit UC" and the driving circuit for outputting the V-phase driving voltage OUT2 is referred to as "V-phase driving circuit VC. ), And a driving circuit for outputting the W phase driving voltage OUT3 will be collectively referred to as "W phase driving circuit WC".

First, the U-phase driving circuit UC will be described.

The U-phase driving circuit UC connects the first switching unit 41H at the top and the second switching unit 41L at the bottom in a totem pole structure between the power supply voltage VDD and the ground, thereby driving the U-phase driving voltage OUT1. Configure the output circuit for. At this time, the U-phase driving voltage OUT1 is output through the output connection point P _U between the first switching unit 41H and the second switching unit 41L.

In detail, the first switching unit 41H is a power switching semiconductor element, and includes a first resistor R1 for limiting the current to the output of the first switching element Q1 and the first gate driver 31 made of an N-type FET. And a first snubber circuit S1 for reducing electromagnetic noise in a radio frequency band by connecting between a drain and a source of the first switching element Q1. do.

First, the first switching element Q1 has a diode D1 for free wheeling back EMF generated from the coils 51 to 53 of the motor 50 at the time of turning off between the drain and the source. Connected. In this case, the power source voltage VDD is connected to the drain of the first switching device Q1.

In addition, the first resistor R1 is connected between the output of the first gate driver 31 and the gate of the first switching element Q1.

In addition, the first snubber circuit S1 is connected between the drain and the source of the first switching element Q1 and disposed in parallel with the first switching element Q1, and the seventh resistor R7 and the first capacitor Configure the RC circuit with C1) connected in series. At this time, the first snubber circuit S1 reduces overshooting when the first switching element Q1 is on / off to reduce electromagnetic noise of the FM frequency band (FIGS. 3A and 3B). 3b). That is, the first snubber circuit S1 suppresses the electromagnetic wave noise of the peak component by reducing the voltage rising rate dV / dt according to the time change when the first switching element Q1 is turned on or off. Reduces electromagnetic noise generated from the motor drive circuit.

On the other hand, the second switching unit 41L disposed below the first switching unit 41H includes a second switching element Q2 and a second resistor R2, and in particular, the second switching element Q2. The second snubber circuit (S2) for connecting between the drain and the source of the. At this time, the source of the second switching device Q2 is grounded.

At this time, the second switching unit 41L has the same structure as the first switching unit 41H, and thus the first switching unit 41H and each component correspond to each other. That is, the second switching element Q2, the second resistor R2, and the second snubber circuit S2, which are the components of the second switching unit 41L, are the first components of the first switching unit 41H. The first switching element Q1, the first resistor R1, and the first snubber circuit S1 respectively correspond to each other. Accordingly, since the second switching unit 41L may be easily understood by those skilled in the art through the description of the first switching unit 41H described above, the overlapping description will be omitted.

However, the output connection point P _U formed between the source of the first switching element Q1 in the upper first switching part 41H and the drain of the second switching element Q2 in the lower second switching part 41L. In FIG. 3, the voltage fluctuations from 0 V to the power supply voltage VDD occur according to the on / off switching operations of the first switching element Q1 and the second switching element Q2. Here, assuming that the first switching device Q1 operating at 5V is turned on, the gate of the first switching device Q1 is set to be + 5V than the output connection point P _U. It is required that the gate signal UH be generated.

In addition, a seventh capacitor C7 forming an X-cap is connected to both ends of the power supply voltages of the first switching unit 41H and the second switching unit 41L to reduce high frequency noise of the power supply voltage VDD.

As described above, the U-phase driving circuit UC is secondarily applied to the electromagnetic noise by the first snubber circuit S1 based on the reduction of the electromagnetic noise by the seventh capacitor C7 forming the X-cap. The reducing interaction ultimately leads to a reduction of electromagnetic noise in the overall broadband frequency band for the 150 kHz to 200 MHz frequency band (especially the radio frequency band-i.e. the AM and FM frequency bands) (Figs. 4c, see FIGS. 5a-5c).

In addition, the Y-cap is applied to the output connection point P _U between the first switching unit 41H and the second switching unit 41L to turn on / off the first switching element Q1 and the second switching element Q2. In order to reduce the high-frequency noise of 200MHz to 300MHz due to the delay effect in the off state, electromagnetic noise is sent to the ground.

On the other hand, the V-phase driving circuit VC and the W-phase driving circuit WC have the same structure as the U-phase driving circuit UC and each component corresponds to each other, so that the V-phase driving circuit VC and the W-phase driving circuit ( The detailed description of WC) is replaced with the above description of the U-phase driving circuit UC.

The V phase driving circuit VC includes a third switching unit 42H at the top and a fourth switching unit 42L at the bottom, and the W phase driving circuit WC is at the top of the fifth switching unit 43H and the bottom. It includes a sixth switching unit 43L. At this time, the third switching unit 42H and the fifth switching unit 43H correspond to the first switching unit 41H, and the fourth switching unit 42L and the sixth switching unit 43L are the second switching unit ( 41L). That is, the second to sixth switching elements Q2 to Q6 correspond to the first switching element Q1. The second to sixth resistors R2 to R6 correspond to the first resistor R1. The second to sixth snubber circuits S2 to S6 correspond to the first snubber circuit S1.

It will be readily understood by those skilled in the art that the present invention can be applied not only to motor driving circuits for automobiles but also to remove electromagnetic noise in conventional motor driving circuits.

4A to 4C are graphs showing electromagnetic noise reduction for an AM frequency band. 4A illustrates a case where only the capacitor of the X-cap is used, FIG. 4B illustrates a case where only the snubber circuit is used, and FIG. 4C illustrates a case where the capacitor and the snubber circuit of the X-cap are used together.

When the X-cap capacitor and snubber circuit of FIG. 4C are used together, the electromagnetic noise is 3 kHz in the 150 kHz region and the AM region (520 GHz to 1.8 MHz) than when only the X-cap capacitor of FIG. 4A is used. In the 150 kHz region and the AM region (520 kHz to 1.8 MHz), the electromagnetic noise was reduced by about 1 kHz compared to the case of using the snubber circuit of FIG. 4B alone.

When the capacitor and the snubber circuit of the X-cap are used at the same time as in FIG. 4C, the electromagnetic wave of the AM frequency band is reduced in the motor drive circuit for automobiles.

5A to 5C are graphs showing electromagnetic noise reduction for an FM frequency band.

5A shows a case where only the capacitor of the X-cap is used, FIG. 5B shows a case where only the snubber circuit is used, and FIG. 5C shows a case where the capacitor and the snubber circuit of the X-cap are used together.

When the X-cap capacitor and snubber circuit of FIG. 5C are used together, electromagnetic noise is reduced by about 10 Hz in the FM region (76 MHz to 108 MHz) than when only the X-cap capacitor of FIG. 5A is used. Electromagnetic noise was reduced in the 40 MHz to 75 MHz region and the 108 MHz to 200 MHz region than the snubber circuit of FIG. 5B.

When using the capacitor and the snubber circuit of the X-cap at the same time as shown in Figure 5c, the electromagnetic wave waveform is generally flattened, especially in the FM frequency band that is important in the motor drive circuit for automobiles is reduced.

6A and 6B are graphs showing electromagnetic noise reduction by Y-cap.

Figure 6a shows before the insertion of the Y-cap, Figure 6b shows after the insertion of the Y-cap. 6A and 6B, it can be seen that the electromagnetic noise reduction effect of the Y-cap in which a 0.001 kHz capacitor is disposed for each output connection point P _U , P _V , P _W in a 100 W motor is shown.

As shown in Figs. 6A and 6B, Y-cap reduces electromagnetic noise to flatten the electromagnetic noise waveform, and in particular, reduces electromagnetic noise for a high frequency band of 200 MHz to 300 MHz.

4A to 6B show a RE test waveform of an electromagnetic compatibility (EMC) test. At this time, the maximum value ⓐ of the generated electromagnetic noise of the inverter 40 should be lower than the regulated maximum electromagnetic noise ⓒ, and the average value ⓑ of the generated electromagnetic noise should be lower than the regulated average electromagnetic noise ⓓ. However, in automobiles, various components generate electromagnetic noise and can affect internal electronics by overlapping electromagnetic noise, so that the electromagnetic noise is managed at a significantly lower electromagnetic noise level than the regulated electromagnetic noise.

In the above, the present invention has been illustrated and described with reference to specific preferred embodiments, but the present invention is not limited to the above-described embodiments, and the present invention is not limited to the spirit of the present invention. Various changes and modifications will be possible by those who have the same.

10: microcomputer 20: logic unit
30: gate driver 40: inverter
41H to 43H: first, third and fifth switching sections 41L to 43L: second, fourth and sixth switching sections
S1 to S6: first to sixth snubber circuits Q1 to Q6: first to sixth switching elements
R1 to R12: first to twelfth resistors C1 to C12: first to twelfth capacitors
50: motor

Claims (8)

As an inverter for driving motors of automobiles,
At least one driving circuit for providing a driving voltage according to the phase,
The drive circuit,
A pair of switching elements for outputting a driving voltage through an output connection point interconnected in a totem pole structure on top and bottom;
A first capacitor disposed at both ends of the power supply of the pair of switching elements to form an X-cap to primarily reduce electromagnetic noise;
A snubber circuit connected in parallel between the drain and the source of each of the pair of switching elements to reduce electromagnetic noise secondly based on the electromagnetic noise level reduced by the first capacitor;
Inverter for driving a motor to reduce electromagnetic noise comprising a. The motor drive inverter according to claim 1, wherein said snubber circuit is formed by connecting a resistor and a second capacitor in series. The motor drive inverter according to claim 1, wherein the driving circuit reduces electromagnetic noise of AM and FM frequency bands which are radio frequency bands. The driving circuit according to any one of claims 1 to 3, wherein the driving circuit is connected between the output connection point of the pair of switching elements and the ground to form a Y-cap for reducing electromagnetic noise in the high frequency band. Inverter for driving a motor to reduce electromagnetic noise, including a third capacitor. As a motor drive device,
It includes; microcomputer, logic unit, gate driver unit, inverter and motor,
The inverter,
Three drive circuits are connected in parallel to provide three-phase driving voltages for U, V, and W phases.
The drive circuit,
A pair of switching elements for outputting a driving voltage through an output connection point interconnected in a totem pole structure on top and bottom;
A first capacitor disposed at both ends of the power supply of the pair of switching elements to form an X-cap to primarily reduce electromagnetic noise;
A snubber circuit connected in parallel between the drain and the source of each of the pair of switching elements, and secondly reducing the electromagnetic noise based on the electromagnetic noise level reduced by the first capacitor;
Motor drive device comprising a. The motor drive device according to claim 5, wherein the snubber circuit is formed by connecting a resistor and a second capacitor in series. 6. The motor driving apparatus according to claim 5, wherein the driving circuit reduces electromagnetic noise of AM frequency band and FM frequency band which are radio frequency bands. 8. The third capacitor as claimed in any one of claims 5 to 7, wherein the driving circuit comprises a Y-cap for reducing electromagnetic noise in the high frequency band between the output connection point of the pair of switching elements and the ground. Motor drive device comprising;

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