Drive circuit and motor system

Abstract

The application discloses a driving circuit and a motor system, wherein the driving circuit comprises a control module, a voltage regulating module, an inverter bridge module and a detection module. The control module is used to generate a first control signal and a second control signal. The voltage regulating module is used to regulate the power voltage based on the control of the first control signal to generate a modulated voltage. The inverter bridge module receives the modulated voltage and drives the motor to rotate based on the control of the second control signal, and the second control signal is a PWM signal with a duty cycle of 100%. The detection module is used to detect the back electromotive force of the motor, and the control module further adjusts the first control signal based on the detection result. The switching loss of each switch tube in the driving circuit and the motor system of the application will be much lower than that in the conventional mode, and the heat generation will also be reduced.

Description

Technical Field

[0001] This application belongs to the field of brushless motor driver technology, specifically relating to a drive circuit and motor system. Background Technology

[0002] For motors used in constant-speed applications, when the motor is under load, a control signal with a corresponding duty cycle must be output to the inverter to maintain the motor's constant speed, while simultaneously ensuring the output power to drive the load. As the load increases, the phase current increases. Since motors used in constant-speed applications adjust their speed by regulating the duty cycle of the inverter's control signal, the instantaneous current value of the phase lines is also affected by the duty cycle. This instantaneous current value is much greater than the instantaneous current value when there is no speed limit, i.e., when the duty cycle is 100%.

[0003] Conventional control methods generate significant switching losses due to the high frequency of switching the transistor on and off, leading to substantial heat generation in the transistor. When the motor load is increased, the current through the transistor also increases, further increasing conduction losses and heat generation. The combined heating from switching and conduction losses causes the transistor's temperature to rise very rapidly.

[0004] When operating motors at constant speeds, it is necessary to control the generation of less heat. This requires upgrading the specifications of all switching transistors accordingly, which is relatively expensive.

[0005] The information disclosed in this background section is intended only to enhance the understanding of the overall background of this application and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Utility Model Content

[0006] The purpose of this application is to provide a drive circuit and motor system that can solve the problems of excessive heat generation and excessive current during motor operation.

[0007] To achieve the above objectives, a specific embodiment of this application provides the following technical solution:

[0008] A drive circuit for a motor, the drive circuit comprising: a control module for generating a first control signal and a second control signal; a voltage regulation module connected to a power supply voltage, which regulates the power supply voltage based on the control of the first control signal to generate a modulated voltage; an inverter bridge module for receiving the modulated voltage and driving the motor to rotate based on the control of the second control signal, wherein the second control signal is a PWM signal with a duty cycle of 100%; and a detection module for detecting the back electromotive force of the motor, wherein the control module further adjusts the first control signal based on the detection result.

[0009] In one or more embodiments of this application, the voltage regulation module includes a switching unit, the first terminal of which is connected to a power supply voltage, and the switching unit periodically turns on or off based on a first control signal to generate a modulation voltage through its second terminal, wherein the first control signal is a PWM signal with a controllable duty cycle.

[0010] In one or more embodiments of this application, the switching unit includes a first switching subunit and a second switching subunit. A first terminal of the first switching subunit is connected to ground voltage, and a second terminal of the first switching subunit is connected to the control terminal of the second switching subunit. The control terminal of the first switching subunit is connected to a control module to receive a first control signal. The first switching subunit controls the connection and disconnection between the control terminal of the second switching subunit and ground voltage based on the first control signal. The first terminal of the second switching subunit is used to form a first terminal of the switching unit, and the second terminal of the second switching subunit is used to form a second terminal of the switching unit. The second switching subunit turns on or off based on the voltage of its own control terminal.

[0011] In one or more embodiments of this application, the first switching subunit includes a first transistor, a first resistor, and a second resistor. A first end of the first resistor is used to form a control terminal of the first switching subunit. The second end of the first resistor and the first end of the second resistor are connected to the control terminal of the first transistor. The second end of the second resistor is connected to the first end of the first transistor to form a first terminal of the first switching subunit. The second end of the first transistor is used to form a second terminal of the first switching subunit.

[0012] In one or more embodiments of this application, the second switching subunit includes a second transistor, a third resistor, and a fourth resistor. The first end of the third resistor is connected to the first end of the second transistor to form the first end of the second switching subunit. The second end of the second transistor is used to form the second end of the second switching subunit. The second end of the third resistor and the first end of the fourth resistor are connected to the control terminal of the second transistor. The second end of the fourth resistor is used to form the control terminal of the second switching subunit.

[0013] In one or more embodiments of this application, the voltage regulating module further includes a first capacitor, a first terminal of which is connected to a second terminal of the switching unit, and a second terminal of which is connected to ground voltage; and / or

[0014] The voltage regulating module also includes a second capacitor, the first end of which is connected to the first end of the switching unit, and the second end of which is connected to ground voltage.

[0015] In one or more embodiments of this application, the detection module includes multiple detection units, each detection unit being connected to a terminal of a corresponding phase in the motor to detect the back electromotive force of the motor based on the voltage of each phase.

[0016] In one or more embodiments of this application, the detection unit includes a fifth resistor, a sixth resistor, and a third capacitor. The first end of the fifth resistor is connected to the terminal of the corresponding phase in the motor. The second end of the fifth resistor, the first end of the sixth resistor, and the first end of the third capacitor are connected to the control module. The second end of the sixth resistor and the second end of the third capacitor are connected to the ground voltage.

[0017] In one or more embodiments of this application, the inverter bridge module includes an inverter bridge unit and an inverter bridge drive unit. The inverter bridge unit includes multiple bridge arms, each bridge arm is connected to a voltage regulation module to receive a modulated voltage, the midpoint of each bridge arm is connected to a motor, and the inverter bridge drive unit is connected to each bridge arm to control the switching of the switching transistors in each bridge arm based on a second control signal.

[0018] One embodiment of this application also provides a motor system, including a motor and the above-described drive circuit, wherein the motor is connected to an inverter bridge module and a detection module.

[0019] Compared to existing technologies, the drive circuit and motor system of this application, by incorporating a voltage regulation module, generates an adjustable modulation voltage as the DC power supply for the inverter bridge module. A PWM signal with a 100% duty cycle is used to control the switching of the inverter bridge module, allowing it to perform only the commutation function of the motor drive, while the speed control function is transferred to the voltage regulation module. In this case, the switching losses of each switch in the inverter bridge module are significantly lower than those under the duty cycle limitation in traditional methods, thus reducing the heat generation of each switch. Simultaneously, the instantaneous current values ​​on each switch do not increase significantly with increased load, remaining far lower than the instantaneous current values ​​under the duty cycle limitation. Therefore, the heat dissipation requirements for each switch can be simultaneously reduced; only the voltage regulation module generates relatively high heat, requiring only upgrades in its specifications or special heat dissipation treatment, thereby reducing component costs. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1This is a circuit diagram of a voltage regulation module in one embodiment of this application.

[0022] Figure 2 This is a circuit schematic diagram of an inverter bridge module in one embodiment of this application.

[0023] Figure 3 This is a circuit diagram of the detection module in one embodiment of this application.

[0024] Figure 4 This is a circuit schematic diagram of the control module in one embodiment of this application. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application.

[0026] The terms "coupled," "connected," or "linked" in this specification include both direct and indirect connections. Indirect connections are those made through an intermediate medium, such as those made through an electrically conductive medium, which may have parasitic inductance or capacitance. Indirect connections may also include connections made through other active or passive devices to achieve the same or similar functional purpose, such as connections through switches, follower circuits, or other circuits or components. Furthermore, in this specification, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship, quantity, or order between these technical features.

[0027] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this application. Therefore, the following detailed description should not be considered limiting.

[0028] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0029] For the purposes of this application, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of this application, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0030] Various components and devices may be mentioned or shown in the singular form herein, but only for the convenience of discussion, and any element mentioned in the singular form may include multiple such elements as taught herein.

[0031] The description uses the phrases "in one embodiment," "in other embodiments," or "in some embodiments," each of which may refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used in relation to embodiments of this application are synonymous.

[0032] Combination Figure 1 , 2 As shown in Figures 3 and 4, the drive circuit in one embodiment of this application can be used for a motor. The drive circuit includes a control module 40, a voltage regulation module 10, an inverter bridge module 20, and a detection module 30.

[0033] The control module 40 generates a first control signal PWM_POW and a second control signal. The voltage regulation module 10 is connected to the power supply voltage and the control module 40, and is used to regulate the power supply voltage based on the control of the first control signal PWM_POW to generate a modulated voltage VR.

[0034] The inverter bridge module 20 is connected to the voltage regulation module 10 to receive the modulated voltage VR. The inverter bridge module 20 drives the motor to rotate based on the control of a second control signal. The second control signal is a PWM signal with a duty cycle of 100%.

[0035] The detection module 30 is used to detect the back electromotive force of the motor. The control module 40 is also connected to the detection module 30 to adjust the first control signal PWM_POW based on the detection result.

[0036] like Figure 1 As shown, the voltage regulating module 10 includes a switching unit 11, a first capacitor C1, and a second capacitor C2.

[0037] The first terminal of the switching unit 11 and the first terminal of the second capacitor C2 are connected to the power supply voltage. The second terminal of the switching unit 11 is connected to the first terminal of the first capacitor C1. The switching unit 11 is periodically turned on or off based on the control of the first control signal PWM_POW to generate a modulation voltage VR through its second terminal. The second terminals of the first capacitor C1 and the second terminal of the second capacitor C2 are connected to the ground voltage.

[0038] Furthermore, the switching unit 11 includes a first switching subunit 111 and a second switching subunit 112. A first terminal of the first switching subunit 111 is connected to ground voltage, and a second terminal of the first switching subunit 111 is connected to the control terminal of the second switching subunit 112. The control terminal of the first switching subunit 111 is connected to the control module 40 to receive a first control signal PWM_POW. The first switching subunit 111 controls the connection and disconnection between the control terminal of the second switching subunit 112 and ground voltage based on the first control signal PWM_POW. A first terminal of the second switching subunit 112 is connected to the power supply voltage and forms the first terminal of the switching unit 11. A second terminal of the second switching subunit 112 forms the second terminal of the switching unit 11. The second switching subunit 112 turns on or off based on the voltage of its own control terminal.

[0039] Specifically, the first switching subunit 111 includes a first transistor Q1, a first resistor R1, and a second resistor R2. The first terminal of the first resistor R1 is connected to the control module 40 to receive the first control signal PWM_POW and forms the control terminal of the first switching subunit 111. The second terminals of the first resistor R1 and the first terminals of the second resistor R2 are connected to the control terminal of the first transistor Q1. The second terminals of the second resistor R2 and the first terminal of the first transistor Q1 are connected to ground voltage and form the first terminal of the first switching subunit 111. The second terminal of the first transistor Q1 is connected to the control terminal of the second switching subunit 112 and forms the second terminal of the first switching subunit 111.

[0040] The second switching subunit 112 includes a second transistor Q2, a third resistor R3, and a fourth resistor R4. The first terminal of the third resistor R3 and the first terminal of the second transistor Q2 are connected to the power supply voltage and form the first terminal of the second switching subunit 112. The second terminal of the second transistor Q2 forms the second terminal of the second switching subunit 112. The second terminal of the third resistor R3 and the first terminal of the fourth resistor R4 are connected to the control terminal of the second transistor Q2, and the second terminal of the fourth resistor R4 is connected to the second terminal of the first transistor Q1, forming the control terminal of the second switching subunit 112.

[0041] In one embodiment, the first transistor Q1 and the second transistor Q2 are N-channel MOSFETs. The first terminal of the first transistor Q1 and the first terminal of the second transistor Q2 are the sources, and the second terminals of the first transistor Q1 and the second transistor Q2 are the drains. The control terminals of the first transistor Q1 and the second transistor Q2 are the gates. In other embodiments, the first transistor Q1 and the second transistor Q2 can also be P-channel MOSFETs or other devices, in which case their connection and control methods are adapted accordingly.

[0042] When the first control signal PWM_POW is high, the first transistor Q1 is turned on, the control terminal voltage of the second transistor Q2 is pulled low, and the second transistor Q2 is turned off. When the first control signal PWM_POW is low, the first transistor Q1 is turned off, the control terminal voltage of the second transistor Q2 is pulled high through the third resistor R3, and the second transistor Q2 is turned on. The periodic switching of the second transistor Q2 achieves the purpose of chopping and regulating the power supply voltage.

[0043] In one embodiment, the first control signal PWM_POW is a PWM signal with a controllable duty cycle. By changing the duty cycle of the first control signal PWM_POW, the magnitude of the modulation voltage VR can be adjusted.

[0044] The voltage regulation module 10 uses only capacitors for filtering. Compared with the LC filtering used in traditional chopper circuits, there is no problem of inductor energy retention, and the dynamic response is faster. Therefore, it is more suitable for complex scenarios such as high current, large load and load changes.

[0045] In other embodiments, the first capacitor C1 and / or the second capacitor C2 may not be provided.

[0046] like Figure 2 As shown, the inverter bridge module 20 includes an inverter bridge unit 21 and an inverter bridge drive unit 22.

[0047] The inverter bridge unit 21 includes multiple bridge arms, each of which is connected to the voltage regulation module 10 to receive the modulation voltage VR, and the midpoint of each bridge arm is connected to the motor.

[0048] In one embodiment, there are three bridge arms: a first bridge arm including a first upper switch Q3 and a first lower switch Q4, a second bridge arm including a second upper switch Q5 and a second lower switch Q6, and a third bridge arm including a third upper switch Q7 and a third lower switch Q8.

[0049] The second terminals of the first upper switch Q3, the second upper switch Q5, and the third upper switch Q7 are connected to the second terminal of the second transistor Q2 in the voltage regulation module 10 to receive the modulation voltage VR. The first terminal of the first upper switch Q3 is connected to the second terminal of the first lower switch Q4 to form the midpoint of the first bridge arm. The first terminal of the second upper switch Q5 is connected to the second terminal of the second lower switch Q6 to form the midpoint of the second bridge arm. The first terminal of the third upper switch Q7 is connected to the second terminal of the third lower switch Q8 to form the midpoint of the third bridge arm. The first terminals of the first lower switch Q4, the second lower switch Q6, and the third lower switch Q8 are connected to ground.

[0050] For example, the midpoint of the first bridge arm can be used as the U-phase output terminal and connected to the U-phase terminal of the motor; the midpoint of the second bridge arm can be used as the W-phase output terminal and connected to the W-phase terminal of the motor; and the midpoint of the third bridge arm can be used as the V-phase output terminal and connected to the V-phase terminal of the motor.

[0051] In one embodiment, the first upper switch Q3, the first lower switch Q4, the second upper switch Q5, the second lower switch Q6, the third upper switch Q7, and the third lower switch Q8 are N-channel MOSFETs. The first terminals of the first upper switch Q3, the first lower switch Q4, the second upper switch Q5, the second lower switch Q6, the third upper switch Q7, and the third lower switch Q8 are the sources; the second terminals of the first upper switch Q3, the first lower switch Q4, the second upper switch Q5, the second lower switch Q6, the third upper switch Q7, and the third lower switch Q8 are the drains; and the control terminals of the first upper switch Q3, the first lower switch Q4, the second upper switch Q5, the second lower switch Q6, the third upper switch Q7, and the third lower switch Q8 are the gates.

[0052] In other embodiments, the first upper switch Q3, the first lower switch Q4, the second upper switch Q5, the second lower switch Q6, the third upper switch Q7, and the third lower switch Q8 can also be P-channel MOSFETs or other devices, in which case their connection and control methods are adapted accordingly. It is understood that a freewheeling diode can also be connected in anti-parallel between the first and second terminals of each switch.

[0053] The inverter bridge drive unit 22 is connected to each bridge arm to control the switching transistors in each bridge arm based on the second control signal.

[0054] In one embodiment, the inverter bridge drive unit 22 includes a first drive subunit 221 connected to the first bridge arm, a second drive subunit 222 connected to the second bridge arm, and a third drive subunit 223 connected to the third bridge arm.

[0055] For example, the first driving subunit 221 includes a first driving chip U1, a first diode D1, a fourth capacitor C4, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10. The high-side input terminal (pin 2) of the first driving chip U1 is connected to the control module 40 to receive the second control signal AH, and the low-side input terminal (pin 3) is connected to the control module 40 to receive the second control signal AL. The high-side output terminal (pin 7) of the first driving chip U1 is connected to the first end of the seventh resistor R7. The second end of the seventh resistor R7 and the first end of the eighth resistor R8 are connected to the control terminal of the first upper switch Q3, and the second end of the eighth resistor R8 is connected to the first end of the first upper switch Q3. The low-side output terminal (pin 5) of the first driving chip U1 is connected to the first end of the ninth resistor R9. The second end of the ninth resistor R9 and the first end of the tenth resistor R10 are connected to the control terminal of the first lower switch Q4, and the second end of the tenth resistor R10 is connected to ground.

[0056] The power supply terminal (pin 1) of the first driver chip U1 and the anode of the first diode D1 are connected to the power supply voltage. The high-side floating power supply terminal (pin 8) of the first driver chip U1 is connected to the cathode of the first diode D1 and the first terminal of the fourth capacitor C4. The high-side bias voltage terminal (pin 6) of the first driver chip U1 is connected to the second terminal of the fourth capacitor C4 and the first terminal of the first upper-side switching transistor Q3. The ground terminal (pin 4) of the first driver chip U1 is connected to the ground voltage.

[0057] like Figure 2 As shown, the structure of the second drive subunit 222 is the same as that of the first drive subunit 221, except that the received second control signal is replaced with the second control signal BH and the second control signal BL, and the connected switching transistors are replaced with the second upper switch Q5 and the second lower switch Q6. The structure of the third drive subunit 223 is the same as that of the first drive subunit 221, except that the received second control signal is replaced with the second control signal CH and the second control signal CL, and the connected switching transistors are replaced with the third upper switch Q7 and the third lower switch Q8. Its specific structure will not be described in detail here.

[0058] The second control signals AH, AL, BH, BL, CH, and CL are all PWM signals with a 100% duty cycle. This means these signals remain high or low throughout a signal cycle, switching between high and low levels in a predetermined sequence as the cycle changes. For example, this predetermined sequence can follow the classic six-step commutation sequence of three-phase electricity. Under the control of these signals, each switching transistor can be turned on and off sequentially according to the set cycle, thus ensuring the orderly direction of the current output to the motor and guaranteeing normal motor rotation. Simultaneously, because the duty cycle of these PWM signals is always 100%, the switching losses and heat generation of each switching transistor are low, and the instantaneous current on each switching transistor will not increase significantly when the load suddenly increases.

[0059] like Figure 3 As shown, the detection module 30 includes multiple detection units, each of which is connected to the terminal of the corresponding phase in the motor to detect the back electromotive force of the motor based on the voltage of each phase.

[0060] In this embodiment, there are three detection units: a first detection unit 31 connected to the U-phase terminal of the motor, a second detection unit 32 connected to the W-phase terminal of the motor, and a third detection unit 33 connected to the V-phase terminal of the motor.

[0061] For example, the first detection unit 31 includes a fifth resistor R5, a sixth resistor R6, and a third capacitor C3. The first end of the fifth resistor R5 is connected to the U-phase terminal of the motor. The second end of the fifth resistor R5, the first end of the sixth resistor R6, and the first end of the third capacitor C3 are connected to the control module 40 and generate a first detection voltage PA. The second end of the sixth resistor R6 and the second end of the third capacitor C3 are connected to ground voltage.

[0062] like Figure 3 As shown, the structure of the second detection unit 32 is the same as that of the first detection unit 31, except that the connection point with the motor is replaced with the W-phase terminal of the motor, and a second detection voltage PB is generated. The structure of the third detection unit 33 is the same as that of the first detection unit 31, except that the connection point with the motor is replaced with the V-phase terminal of the motor, and a third detection voltage PC is generated. Its specific structure will not be described in detail here.

[0063] Based on the first detection voltage PA, the second detection voltage PB, and the third detection voltage PC, the control module 40 can obtain the back electromotive force detection result of the motor and further calculate the real-time speed of the motor.

[0064] In other embodiments, the number of detection units may also be different.

[0065] like Figure 4As shown, the control module 40 includes a control chip U4. In one embodiment, the control chip U4 may be an MCU chip.

[0066] Pin 2 of control chip U4 generates the first control signal PWM_POW and is connected to the first terminal of the first resistor in voltage regulation module 10. Pins 3, 4, 5, 6, 7, and 8 of control chip U4 are used to generate the second control signals CH, CL, BH, BL, AH, and AL, respectively, and are connected to the corresponding drive subunits. Pin 24 of control chip U4 is connected to the first detection unit 31 to receive the first detection voltage PA, pin 22 of control chip U4 is connected to the second detection unit 32 to receive the second detection voltage PB, and pin 21 of control chip U4 is connected to the third detection unit 33 to receive the third detection voltage PC.

[0067] In actual operation, the control module 40 generates a first control signal PWM_POW with a certain duty cycle to control the voltage regulation module 10 to regulate the voltage, generating a modulated voltage VR of a certain magnitude. Then, the inverter bridge module 20 sends the modulated voltage VR to each terminal of the motor and drives the motor to rotate. Finally, the control module 40 calculates the instantaneous operating speed of the motor by detecting the back electromotive force, and then adjusts the duty cycle of the first control signal PWM_POW to further adjust the voltage input to the motor, so that the final output speed of the motor reaches the ideal speed.

[0068] In the above process, since the second control signal controlling the switching of the inverter bridge unit 21 is a PWM signal with a 100% duty cycle, the losses of each switching transistor will be much lower than the switching losses under the duty cycle limitation, thus reducing the heat generation of the switching transistors. Simultaneously, because it is a 100% duty cycle, the instantaneous current value on the switching transistors will not increase significantly due to the increased load; this instantaneous current value will be much lower than the instantaneous current value under the duty cycle limitation, thus reducing the heat generated by both turn-on and conduction losses.

[0069] Therefore, the heat dissipation treatment of each switching transistor in the inverter bridge unit 21 can also be reduced accordingly. Only the second transistor Q2 in the voltage regulation module 10 will generate a relatively large amount of heat. It is only necessary to upgrade the specifications of the second transistor Q2 or to carry out special heat dissipation treatment, which greatly reduces the cost.

[0070] Furthermore, in the voltage regulation module 10, the energy retention problem is eliminated by selecting capacitor filtering.

[0071] It has a faster dynamic response and is more suitable for complex scenarios such as high current, high load and load changes.

[0072] This embodiment also provides a motor system, including a motor and the aforementioned drive circuit. The motor is connected to the inverter bridge module 20 and the detection module 30 in the drive circuit.

[0073] In one embodiment, the motor is a three-phase AC motor. The U-phase terminal of the motor is connected to the midpoint of the first bridge arm and the first detection unit 31, the W-phase terminal of the motor is connected to the midpoint of the second bridge arm and the second detection unit 32, and the V-phase terminal of the motor is connected to the midpoint of the third bridge arm and the third detection unit 33.

[0074] It will be apparent to those skilled in the art that this application is not limited to the details of the exemplary embodiments described above, and that this application can be implemented in other specific forms without departing from the spirit or essential characteristics of this application. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this application is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this application. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0075] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A drive circuit for an electric machine, characterized in that The driving circuit includes: The control module is used to generate the first control signal and the second control signal; The voltage regulation module is connected to the power supply voltage and generates a modulated voltage by regulating the power supply voltage based on the control of the first control signal. The inverter bridge module receives the modulated voltage and drives the motor to rotate based on the second control signal, which is a PWM signal with a duty cycle of 100%. The detection module is used to detect the back electromotive force of the motor, and the control module also adjusts the first control signal based on the detection result.

2. The drive circuit according to claim 1, characterized in that, The voltage regulation module includes a switching unit. The first terminal of the switching unit is connected to the power supply voltage. The switching unit periodically turns on or off based on a first control signal to generate a modulation voltage through its second terminal. The first control signal is a PWM signal with a controllable duty cycle.

3. The drive circuit according to claim 2, characterized in that, The switching unit includes a first switching subunit and a second switching subunit. A first terminal of the first switching subunit is connected to ground voltage, and a second terminal of the first switching subunit is connected to the control terminal of the second switching subunit. The control terminal of the first switching subunit is connected to a control module to receive a first control signal. The first switching subunit controls the connection and disconnection between the control terminal of the second switching subunit and ground voltage based on the first control signal. The first terminal of the second switching subunit is used to form the first terminal of the switching unit, and the second terminal of the second switching subunit is used to form the second terminal of the switching unit. The second switching subunit turns on or off based on the voltage of its own control terminal.

4. The driving circuit according to claim 3, characterized in that, The first switching subunit includes a first transistor, a first resistor, and a second resistor. The first end of the first resistor is used to form the control terminal of the first switching subunit. The second end of the first resistor and the first end of the second resistor are connected to the control terminal of the first transistor. The second end of the second resistor is connected to the first end of the first transistor to form the first terminal of the first switching subunit. The second end of the first transistor is used to form the second terminal of the first switching subunit.

5. The driving circuit according to claim 3, characterized in that, The second switching subunit includes a second transistor, a third resistor, and a fourth resistor. The first end of the third resistor is connected to the first end of the second transistor to form the first end of the second switching subunit. The second end of the second transistor is used to form the second end of the second switching subunit. The second end of the third resistor and the first end of the fourth resistor are connected to the control end of the second transistor. The second end of the fourth resistor is used to form the control end of the second switching subunit.

6. The driving circuit according to claim 2, characterized in that, The voltage regulation module further includes a first capacitor, a first terminal of which is connected to a second terminal of the switching unit, and a second terminal of which is connected to ground voltage; and / or The voltage regulating module also includes a second capacitor, the first end of which is connected to the first end of the switching unit, and the second end of which is connected to ground voltage.

7. The driving circuit according to claim 1, characterized in that, The detection module includes multiple detection units, each of which is connected to the terminal of the corresponding phase in the motor to detect the back electromotive force of the motor based on the voltage of each phase.

8. The driving circuit according to claim 7, characterized in that, The detection unit includes a fifth resistor, a sixth resistor, and a third capacitor. The first end of the fifth resistor is connected to the terminal of the corresponding phase in the motor. The second end of the fifth resistor, the first end of the sixth resistor, and the first end of the third capacitor are connected to the control module. The second end of the sixth resistor and the second end of the third capacitor are connected to the ground voltage.

9. The driving circuit according to claim 1, characterized in that, The inverter bridge module includes an inverter bridge unit and an inverter bridge drive unit. The inverter bridge unit includes multiple bridge arms, each of which is connected to a voltage regulation module to receive a modulated voltage. The midpoint of each bridge arm is connected to a motor. The inverter bridge drive unit is connected to each bridge arm to control the switching transistors in each bridge arm based on a second control signal.

10. A motor system, characterized in that, It includes a motor and a drive circuit as described in any one of claims 1 to 9, wherein the motor is connected to an inverter bridge module and a detection module.

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