Drive circuits and automotive motor drive systems with EMI suppression

Abstract

This invention discloses a drive circuit with EMI suppression and an automotive motor drive system. The EMI suppression drive circuit includes: a first filter unit, a second filter unit, a third filter unit, a drive power supply, and a drive chip. The first filter unit includes a differential-mode filter unit and a common-mode filter unit. In this embodiment, the power supply is filtered by the common-mode inductor filter unit and the differential-mode filter unit. The second filter unit supplies power to the drive chip, and the third filter unit supplies power to the drive power supply. In this way, the third filter unit separates the drive power supply from the drive chip, solving the problem of electromagnetic interference caused by transient voltage and current fluctuations in existing power semiconductor devices on the low-voltage power supply circuit, which in turn interferes with other electronic devices in the vehicle.

Description

Technical Field

[0001] This invention relates to the field of EMI suppression drive circuit technology, and more particularly to a drive circuit with EMI suppression and an automotive motor drive system. Background Technology

[0002] With technological advancements, power supply solutions for new energy vehicle motor drive controllers often employ power chips driving MOSFETs to build flyback switching power supply topologies. These switching power supplies are susceptible to electromagnetic interference (EMI). The main sources of this interference are power switching devices, transformers, and output rectifier diodes. Power switching devices, due to high-frequency switching cycles and their own parasitic capacitance, experience rapid changes in both voltage and current rates, thus increasing the intensity of EMI. High-frequency transformers, due to leakage inductance, generate a high voltage spike at the moment of power supply turn-off, which also impacts EMI. The output rectifier diodes also generate a high voltage spike during reverse recovery, further affecting EMI.

[0003] Traditional EMI suppression circuits are all single-stage π-type filter units, or add common-mode inductors and Y capacitors at the high-voltage end. EMI suppression circuits cannot effectively suppress EMI interference from the driver board (which is equipped with a driver controller). Summary of the Invention

[0004] This invention provides a drive circuit and automotive motor drive system with EMI suppression, which effectively suppresses EMI interference in the low-voltage loop of the drive unit circuit.

[0005] In a first aspect, embodiments of the present invention provide an EMI suppression driving circuit, the driving circuit including a first filter unit, a second filter unit, a third filter unit, a driving power supply, and a driving chip;

[0006] The first filter unit is connected to the power supply.

[0007] The second filter unit is connected between the first filter unit and the input terminal of the drive power supply;

[0008] The third filtering unit is connected between the second filtering unit and the first input terminal of the driver chip;

[0009] The second input terminal of the driver chip is connected to the output terminal of the driver power supply; wherein, the first filtering unit includes a differential-mode filtering unit and a common-mode filtering unit, and the second filtering unit and the third filtering unit are π-type filtering units.

[0010] Optionally, the first filtering unit includes a common-mode inductor, a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor;

[0011] Wherein, the first and second ends of the common mode inductor are connected to the power supply, and the third end of the common mode inductor is connected to the first filter unit;

[0012] The first capacitor is connected between the first terminal of the common mode inductor and the device housing, the second capacitor is connected between the second terminal of the common mode inductor and the device housing, the third capacitor is connected between the third terminal of the common mode inductor and the device housing, and the fourth capacitor is connected between the fourth terminal of the common mode inductor and the device housing.

[0013] Optionally, the first filtering unit further includes a fifth capacitor and a sixth capacitor; one end of the fifth capacitor is connected to the first terminal of the common-mode inductor, and the other end is grounded; one end of the sixth capacitor is connected to the third terminal of the common-mode inductor, and the other end is grounded.

[0014] The second filter unit includes a first inductor, a seventh capacitor, and an eighth capacitor.

[0015] The first end of the first inductor is connected to the first filter unit, and the second end of the first inductor is connected to the input terminal of the drive power supply and the third filter unit.

[0016] One end of the seventh capacitor is connected to the first end of the first inductor, and the other end is grounded.

[0017] One end of the eighth capacitor is connected to the second end of the first inductor, and the other end is grounded.

[0018] Optionally, the third filtering unit includes: a second inductor, a ninth capacitor, and a tenth capacitor;

[0019] The first end of the second inductor is connected to the second filter unit, and the second end of the second inductor is connected to the first input terminal of the driver chip;

[0020] One end of the ninth capacitor is connected to the first end of the second inductor, and the other end is grounded;

[0021] One end of the tenth capacitor is connected to the second end of the second inductor, and the other end is grounded.

[0022] Optionally, the driving circuit may further include an eleventh capacitor, which is connected in parallel with the tenth capacitor.

[0023] The power supply is a low-voltage power supply with a voltage of less than or equal to 48V.

[0024] The power supply voltage is 12V.

[0025] The output terminal of the driver chip is connected to the IGBT module, and the IGBT module is connected to the high-voltage power supply and the motor.

[0026] This invention provides a driving circuit and automotive motor drive system with EMI suppression. It suppresses common-mode interference through a common-mode inductor, filters differential-mode interference through a differential-mode capacitor, and effectively isolates the driving power supply and the driving chip through a first-stage π-type filter and a second-stage π-type filter, thus avoiding electromagnetic wave coupling and superposition interference. This effectively suppresses the low-voltage EMI interference circuit of the driving unit circuit.

[0027] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of an EMI suppression drive circuit in the prior art;

[0030] Figure 2 This is a schematic diagram of a driving unit circuit structure that effectively suppresses EMI according to Embodiment 1 of the present invention;

[0031] Figure 3 This is a circuit diagram of an EMI suppression driving circuit provided according to Embodiment 1 of the present invention; Detailed Implementation

[0032] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0033] In existing technologies, EMI in motor drive systems is mainly conducted interference. The main sources of interference are power switching devices, transformers, and output rectifier diodes. Among them, the high-frequency switching cycles of power switching devices and their own parasitic capacitance cause rapid changes in both voltage and current rates, which increases EMI interference. Traditional EMI suppression circuits typically use a single-stage π-type filter unit or add a common-mode inductor and Y capacitor at the high-voltage end, while EMI protection circuits on the driver board are relatively rare.

[0034] In response to the technical problems existing in the present invention, this embodiment provides a drive circuit with EMI suppression, which can be used to solve the problem in the prior art where transient voltage and current generated by power semiconductor devices cause electromagnetic interference to the low-voltage power supply circuit, thereby interfering with other electronic devices in the vehicle. Figure 1 A schematic diagram of an EMI suppression drive circuit structure in the prior art, such as... Figure 1 As shown, the power supply is a low-voltage 12V battery. After passing through a π-type filter, the power supply simultaneously powers both the drive power supply and the drive chip. The π-type filter acts as a bidirectional filter, reducing EMI radiation from the drive unit to the low-voltage 12V battery circuit. However, since both the drive power supply and the drive chip are powered by low-voltage 12V batteries through the π-type filter, electromagnetic waves may couple and superimpose, causing interference. This does not effectively suppress EMI interference from the drive power supply to the low-voltage circuit.

[0035] Figure 2 A schematic diagram of a driving unit circuit structure for effectively suppressing EMI is provided in an embodiment of the present invention, as shown below. Figure 2As shown, the EMI-suppressing drive circuit includes: a first filter unit 110, a second filter unit 120, a third filter unit 130, a drive power supply 140, and a drive chip 150. The first filter unit 110 is connected to the power supply 100; the second filter unit 120 is connected between the first filter unit and the input terminal of the drive power supply 140; the third filter unit 130 is connected between the second filter unit 120 and the first input terminal of the drive chip 150; the second input terminal of the drive chip 150 is connected to the output terminal of the drive power supply 140. The first filtering unit 110 includes a common-mode inductor filtering unit and a differential-mode inductor filtering unit. The second filtering unit 120 includes a π-type filtering unit, which is also a first-stage π-type filtering unit. The third filtering unit 130 includes a π-type filtering unit, which is also a second-stage π-type filtering unit. The power supply 100 first passes through the common-mode inductor filtering unit and the differential-mode filtering unit (the first filtering unit) to filter and attenuate the common-mode interference in the power supply circuit and reduce the bypass differential-mode interference of the power supply circuit. Then, it passes through the second filtering unit 120 (the first-stage π-type filtering unit) to supply power to the drive power supply, and then through the third filtering unit 130 (the second-stage π-type filtering unit) to supply power to the drive chip 150. In this way, the third filtering unit 130 (the second-stage π-type filtering unit) can reduce the problem of electromagnetic wave mutual interference coupling and superposition between the drive power supply and the drive chip, based on the filtering effect. The power supply 100 supplies power to the driver chip 150 through the first filter unit 110, the second filter unit 120, and the third filter unit 130. The driver power supply 140 supplies power to the driver chip 150, and the driver chip 150 supplies power to the IGBT module 160.

[0036] Figure 3 A circuit diagram of an EMI suppression driving circuit is provided for an embodiment of the present invention, such as... Figure 3As shown, a drive circuit with EMI suppression includes a first filter unit 110, a second filter unit 120, a third filter unit 130, a drive power supply 140, and a drive chip 150. A controller 1 provides a low-voltage power supply, which powers the drive power supply 140 and the drive chip 150 through the first filter unit 110, the second filter unit 120, and the third filter unit 130. The first filter unit 110 is connected between the power supply and the second filter unit 120, and includes a differential-mode filter unit and a common-mode filter unit. A common-mode inductor L3, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4 together constitute the common-mode filter unit of this EMI suppression drive circuit. The common-mode inductor L3 attenuates common-mode interference in the power supply circuit, and the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are grounded to filter the common-mode current output by the power supply circuit. The fifth capacitor C5 and the sixth capacitor C6 form the differential-mode filter unit of this EMI suppression drive circuit. As differential-mode capacitors, they reduce bypass differential-mode interference in the power supply circuit.

[0037] The second filter unit 120 is a first-stage π-type filter unit, and the third filter unit 130 is a second-stage π-type filter unit. The π-type filter unit can be constructed from π filters, which are bidirectional low-pass filters, significantly different from traditional LC filters. When a π filter is used for low-pass filtering, the output is stable and the K value is fixed. For example, a π filter circuit consists of two capacitors connected in parallel and an inductor connected in series, forming a π-shaped circuit. It generates high impedance at high frequencies and low impedance at low frequencies. In this embodiment, the output of the first-stage π-type filter unit supplies power to the drive power supply, and the output of the second-stage π-type filter unit supplies power to the drive chip. The second-stage π-type filter unit isolates and filters the power supply circuits of the drive power supply and the drive chip, reducing electromagnetic interference from mutual coupling between the drive power supply and the drive chip, effectively suppressing EMI interference in the low-voltage circuit of the drive unit circuit.

[0038] Figure 3 This is a schematic diagram of another driving unit circuit structure that effectively suppresses EMI, provided by an embodiment of the present invention. Please refer to it. Figure 3 Based on the above embodiments, the first filter unit 110 includes a common-mode inductor L3, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a fourth capacitor C4. The first and second ends of the common-mode inductor L3 are connected to the power supply, and the third end of the common-mode inductor L3 is connected to the first filter unit 110.

[0039] The first capacitor C1 is connected between the first terminal of the common-mode inductor L3 and the device housing, and is used to filter the common-mode current output by the power supply circuit.

[0040] The second capacitor C2 is connected between the second terminal of the common-mode inductor L3 and the device housing, and is used to filter the common-mode current output by the power supply circuit.

[0041] The third capacitor C3 is connected between the third terminal of the common-mode inductor L3 and the device housing, and is used to filter the common-mode current output by the power supply circuit.

[0042] The fourth capacitor C4 is connected between the fourth terminal of the common-mode inductor L4 and the device housing, and is used to filter the common-mode current output by the power supply circuit.

[0043] The first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 are connected to the device casing, which is equivalent to grounding the other end, and can filter the common-mode current output by the power supply circuit.

[0044] The common-mode inductor L3, the first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4 together constitute the common-mode filter unit of this EMI suppression drive circuit. The common-mode inductor L3 can attenuate the common-mode interference in the power supply circuit. The first capacitor C1, the second capacitor C2, the third capacitor C3, and the fourth capacitor C4, which form the grounding capacitor, are used to filter the common-mode current output by the power supply circuit. In addition, the copper wire windings on the common-mode inductor L3 are in the same phase, but the electromagnetic interference AC voltage through the windings is not in phase. Therefore, two AC magnetic fluxes of different phases will be generated on the common-mode inductor core, which can cancel each other out.

[0045] Optionally, the first filter unit 110 further includes a fifth capacitor C5 and a sixth capacitor C6.

[0046] One end of the fifth capacitor C5 is connected to the first end of the common-mode inductor L3, and the other end is grounded.

[0047] One end of the sixth capacitor C6 is connected to the third terminal of the common-mode inductor L3, and the other end is grounded.

[0048] The fifth capacitor C5 and the sixth capacitor C6 form the differential mode filter unit of the EMI suppression drive circuit. The fifth capacitor C5 and the sixth capacitor C6 are connected in parallel across the common mode inductor L3 as two differential mode capacitors. The fifth capacitor C5 is connected to the power supply, and the sixth capacitor C6 is connected in parallel with the power supply. The bypass differential mode interference of the power supply circuit can be reduced through the fifth capacitor C5 and the sixth capacitor C6.

[0049] Optionally, the second filter unit 120 includes a first inductor L1, a seventh capacitor C7, and an eighth capacitor C8. The first end of the first inductor L1 is connected to the first filter unit, and the second end of the first inductor L1 is connected to the input terminal of the driving power supply and the third filter unit.

[0050] One end of the seventh capacitor C7 is connected to the first end of the first inductor L1, and the other end is grounded.

[0051] One end of the eighth capacitor C8 is connected to the second end of the first inductor L1, and the other end is grounded.

[0052] The first inductor L1, the seventh capacitor C7, and the eighth capacitor C8 together constitute a first-stage π-type filter unit, namely the second filter unit 120. The output of the second filter unit 120 (the first-stage π-type filter unit) supplies power to the drive power supply. The low-voltage power from the power supply is transmitted to the second filter unit 120 after passing through the first filter unit 110. The low-voltage power transmitted to the second filter unit 120 undergoes the first filtering by the first filter unit 110, which attenuates the common-mode interference in the power supply circuit and reduces the bypass differential-mode interference of the power supply circuit.

[0053] A π-type filter circuit consists of two capacitors connected in parallel, and then an inductor connected in series, forming a π-shaped circuit. It generates high impedance at high frequencies and low impedance at low frequencies. There are two types of π-type filters: RC and LC. RC filters are used when the output current is small. The value of R should not be too large, typically a few to tens of ohms. Its advantage is low cost. Its disadvantage is that the resistor consumes some energy, and its effect is not as good as an LC circuit. Using a larger filter capacitor can also produce good results. An LC circuit contains an inductor, and the inductance value is selected based on the output current and frequency. Its disadvantage is that the inductor is large, bulky, and expensive. Most existing electronic circuits use RC filters in their power supplies. LC filter circuits are rarely used. In this embodiment, a filter circuit is chosen to remove unwanted harmonics, which in a DC power supply reduces current ripple and makes the current smoother.

[0054] Optionally, the third filter unit 130 includes a second inductor L2, a ninth capacitor C9, and a tenth capacitor C10; the first end of the second inductor L2 is connected to the second filter unit 120, and the second end of the second inductor L2 is connected to the first input terminal of the driver chip.

[0055] One end of the ninth capacitor C9 is connected to the first end of the second inductor L2, and the other end is grounded.

[0056] One end of the tenth capacitor C10 is connected to the second end of the second inductor L2, and the other end is grounded.

[0057] The second inductor L2, the ninth capacitor C9, and the tenth capacitor C10 together constitute a two-stage π-type filter unit, namely the third filter unit 130. The output of the second filter unit 120 (the first-stage π-type filter unit) supplies power to the drive power supply, while the output of the third filter unit 130 (the second-stage π-type filter unit) supplies power to the drive chip. The third filter unit 130 (the second-stage π-type filter unit) isolates and filters the power supply circuits of the drive power supply and the drive chip, reducing the mutual coupling and superposition interference of electromagnetic waves between the drive power supply and the drive chip, and can effectively suppress the EMI interference low-voltage circuit of the drive unit circuit.

[0058] Optionally, the third filter unit 130 also includes an eleventh capacitor C11, which is connected in parallel with the tenth capacitor C10.

[0059] The power supply is a low-voltage power supply with a voltage of less than or equal to 48V.

[0060] Preferably, the voltage of the power supply is 12V.

[0061] The output terminal of the driver chip is connected to the IGBT module, which is connected to the high-voltage power supply and the motor. The IGBT module contains MOSFETs S1, S2, S3, S4, S5, and S6. The motor operation is controlled by switching the MOSFETs in the IGBT module on and off.

[0062] In this embodiment, common-mode interference is suppressed by a common-mode inductor, differential-mode interference is filtered out by a differential-mode capacitor, and the drive power supply and drive chip are effectively isolated by a first-stage π-type filter and a second-stage π-type filter, avoiding electromagnetic wave coupling and superposition interference. This effectively suppresses EMI interference in the low-voltage loop of the drive unit circuit. The parameters of the common-mode inductor, differential-mode capacitor, first-stage π-type filter unit, and second-stage π-type filter unit can be matched according to different drive power supplies and drive chips, exhibiting good adaptability. The common-mode inductor, differential-mode capacitor, first-stage π-type filter unit, and second-stage π-type filter unit are all low-cost components, offering good economic efficiency.

[0063] The automotive motor drive system described in this embodiment includes a drive circuit with EMI suppression provided in any embodiment of the present invention.

[0064] In this embodiment of the invention, by setting the EMI suppression drive circuit in the automotive motor drive system, the electromagnetic interference caused by transient voltage and current generated by power semiconductor devices on the low-voltage power supply circuit can be solved, thereby preventing it from interfering with other electronic devices in the vehicle.

[0065] Note that the above description is merely a preferred embodiment of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and various obvious changes, readjustments, and substitutions can be made without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments, and may include many other equivalent embodiments without departing from the concept of the present invention, the scope of which is determined by the scope of the appended claims.

Claims

1. A drive circuit having EMI suppression, characterized by, The first filter unit, the second filter unit, the third filter unit, the driving power supply and the driving chip are included. The first filter unit is connected to the power supply. The second filter unit is connected between the first filter unit and the input end of the driving power supply. The third filter unit is connected between the second filter unit and the first input end of the driving chip. The second input end of the driving chip is connected to the output end of the driving power supply. The first filter unit includes a differential mode filter unit and a common mode filter unit, the second filter unit and the third filter unit are π-type filter units, and the third filter unit is used for isolating and filtering the driving power supply and the driving chip power supply loop. The third filter unit includes a second inductor, a ninth capacitor and a tenth capacitor. The first end of the second inductor is connected to the second filter unit, and the second end of the second inductor is connected to the first input end of the driving chip. One end of the ninth capacitor is connected to the first end of the second inductor, and the other end is grounded.

2. The drive circuit according to claim 1, characterized in that, One end of the tenth capacitor is connected to the second end of the second inductor, and the other end is grounded. The first filter unit includes a common mode inductor, a first capacitor, a second capacitor, a third capacitor and a fourth capacitor. The first end and the second end of the common mode inductor are connected to the power supply, and the third end of the common mode inductor is connected to the first filter unit.

3. The drive circuit according to claim 2, characterized in that, The first capacitor is connected between the first end of the common mode inductor and the device shell, the second capacitor is connected between the second end of the common mode inductor and the device shell, the third capacitor is connected between the third end of the common mode inductor and the device shell, and the fourth capacitor is connected between the fourth end of the common mode inductor and the device shell.

4. The drive circuit according to claim 1, characterized by The first filter unit further includes a fifth capacitor and a sixth capacitor, one end of the fifth capacitor is connected to the first end of the common mode inductor, and the other end is grounded, and one end of the sixth capacitor is connected to the third end of the common mode inductor, and the other end is grounded. The second filter unit includes a first inductor, a seventh capacitor and an eighth capacitor. The first end of the first inductor is connected to the first filter unit, and the second end of the first inductor is connected to the input end of the driving power supply and the third filter unit. One end of the seventh capacitor is connected to the first end of the first inductor, and the other end is grounded.

5. The drive circuit according to claim 1, characterized by One end of the eighth capacitor is connected to the second end of the first inductor, and the other end is grounded.

6. The drive circuit according to claim 2, characterized by The eleventh capacitor is further included and is connected in parallel with the tenth capacitor.

7. The drive circuit according to claim 6, characterized in that, The power supply is a low-voltage power supply, and the voltage of the power supply is less than or equal to 48V.

8. The drive circuit of claim 6, wherein, The voltage of the power supply is 12V.

9. An automotive motor drive system, characterized by, The output end of the driving chip is connected to an IGBT module, and the IGBT module is connected to a high-voltage power supply and a motor. The driving circuit with EMI suppression of any one of claims 1-8 is included.

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