阅读说明：本技术 用于电机驱动器中的开关电源的电路、操作方法和电机驱动电路系统 (Circuit for switching power supply in motor driver, operation method and motor driving circuit system ) 是由 李君峰 于 2019-11-28 设计创作，主要内容包括：本公开提供了一种用于电机驱动器中的开关电源的电路。该电路包括检测电路,耦合至开关电源,并且被配置用于检测开关电源中的功率开关器件的短路失效并且响应于检测到短路失效生成故障信号；以及控制器,耦合至检测电路并且被配置用于响应于接收到故障信号使得电机驱动器中的逆变电路短路。通过使用根据本公开实施例的电路,能够获取开关电源电路中的功率开关器件的状态,并且能够在功率开关器件出现短路失效的情况下第一时间做出响应,使得逆变电路短路来提高开关电源电路乃至整个电机驱动器的安全性。(The present disclosure provides a circuit for a switching power supply in a motor driver. The circuit includes a detection circuit coupled to the switching power supply and configured to detect a short circuit failure of a power switching device in the switching power supply and generate a fault signal in response to detecting the short circuit failure; and a controller coupled to the detection circuit and configured to short circuit an inverter circuit in the motor drive in response to receiving the fault signal. By using the circuit according to the embodiment of the disclosure, the state of the power switch device in the switching power supply circuit can be obtained, and the response can be made at the first time under the condition that the power switch device is short-circuited and fails, so that the safety of the switching power supply circuit and even the whole motor driver is improved by short-circuiting the inverter circuit.)

1. A circuit for a switching power supply in a motor drive, comprising:

a detection circuit (101) coupled to the switching power supply (201) and configured to detect a short circuit failure of a power switching device (203) in the switching power supply (201) and generate a fault signal in response to detecting the short circuit failure; and

a controller (103) coupled to the detection circuit (101) and configured to short circuit an inverter circuit (202) in the motor drive in response to receiving the fault signal.

2. The circuit of claim 1, wherein the detection circuit (101) is further configured for:

detecting a trigger voltage (V) between a control terminal (G) and the second terminal (D) of the power switch device (203) in the switching power supply (201)_GD) And the cut-off voltage (V) of the first terminal (S) and the second terminal (D)_DS) (ii) a And

in response to the trigger voltage (V)_GD) Is lower than a first threshold value and the cut-off voltage (V)_DS) Below a second threshold, the fault signal is generated.

3. The circuit of claim 1, wherein the detection circuit is further configured to:

detecting a voltage across a resistor (204) coupled to the power switch device (203) in the switching power supply (201); and

generating the fault signal in response to a voltage across the resistor (204) exceeding a third threshold.

4. The circuit of claim 2, wherein the detection circuit (101) comprises:

a first comparison circuit coupled to the power switch device (203) and configured for being based on the received cut-off voltage (Vv)_DS) And a reference voltage (V)_ref) Generating a first electrical signal;

a second comparison circuit coupled to the power switch device (203) and configured for being based on the received trigger voltage (Vv)_GD) And the reference voltage (V)_ref) Generating a second electrical signal; and

a third comparison circuit coupled to the first and second comparison circuits and configured to generate the fault signal based on the first and second electrical signals.

5. The circuit of claim 4, wherein the first comparison circuit comprises:

a first voltage division circuit (1012) configured to divide the off-voltage (V)_DS) Dividing the voltage into a first voltage; and

a first comparator (1014), an inverting input of the first comparator (1014) coupled to the first voltage divider circuit to receive the first voltage and configured to be based on the first voltage and the reference voltage (Vref)_ref) Generating the first electrical signal.

6. The circuit of claim 5, wherein the second comparison circuit comprises:

a second voltage division circuit (1013) configured to divide the trigger voltage (V)_GD) Dividing the voltage into a second voltage; and

a second comparator (1015), an inverting input of the second comparator (1015) coupled to the second voltage-dividing circuit to receive the second voltage and configured to be based on the second voltage and the reference voltage (Vref)_ref) Generating the second electrical signal.

7. The circuit of claim 6, wherein the reference voltage (V)_ref) Is an average of the first voltage and the second voltage.

8. The circuit of claim 6, wherein the third comparison circuit comprises:

an RC circuit coupled to outputs of the first comparator (1014) and the second comparator (1015);

a third comparator (1016), an inverting input of the third comparator (1016) coupled to the RC circuit to receive an RC voltage; and

a feedback circuit (1017) coupled between a non-inverting input of the third comparator (1016) and an output of the third comparator (1016) to provide a feedback voltage to the non-inverting input of the third comparator (1016).

9. The circuit of claim 8, wherein the feedback circuit (1017) is configured to be responsive to the trigger voltage (V)_GD) Is lower than the first threshold and the cut-off voltage (V)_DS) Below the second threshold, such that the feedback voltage is below the RC voltage to generate the fault signal.

10. The circuit of claim 8, wherein the RC circuit comprises: a first resistor (R1), a first end of the first resistor (R1) coupled to a voltage source (Vcc);

a capacitor (C) between the second end of the first resistor (R1) and ground;

a second resistor (R2), a first end of the second resistor (R2) being coupled to an output of the first comparator (1014) and a second end of the second resistor (R2) being coupled to the second end of the first resistor (R1) and the inverting input of the third comparator (1016); and

a third resistor (R3), a first end of the third resistor (R3) being coupled to an output of the second comparator (1015), and a second end of the third resistor (R3) being coupled to the second end of the first resistor (R1) and the inverting input of the third comparator (1016).

11. A motor drive circuitry comprising:

a rectifying circuit (205) coupled to the power supply for rectifying an input electrical signal for output;

a switching power supply (201) coupled to an output of the rectifying circuit and comprising a circuit according to any of claims 1-10; and

an inverter circuit (202) coupled to the rectifier circuit (205) for outputting an electrical signal to drive a motor.

12. A method of operating a switching power supply for a motor drive, comprising:

receiving a fault signal from a detection circuit (101) coupled to the switching power supply (201), wherein the detection circuit (101) is to detect a short circuit failure of a power switching device (203) in the switching power supply (201) and to generate a fault signal in response to detecting the short circuit failure; and

short-circuiting an inverter circuit in the motor driver in response to receiving the fault signal.

13. The method of operation of claim 12, wherein receiving a fault signal comprises:

receiving the fault signal from a detection circuit (101) coupled to the power switch device (203), wherein the detection circuit (101) is configured to: detecting a trigger voltage (V) between a control terminal (G) and the second terminal (D) of the power switch device (203) in the switching power supply (201)_GD) And the cut-off voltage (V) of the first terminal (S) and the second terminal (D)_DS) (ii) a And in response to said trigger voltage (V)_GD) Is lower than a first threshold value and the cut-off voltage (V)_DS) Below a second threshold, the fault signal is generated.

14. The method of operation of claim 12, wherein receiving a fault signal comprises:

receiving the fault signal from a detection circuit (101) coupled to the power switch device (203), wherein the detection circuit (101) is configured to: detecting a voltage across a resistor (204) coupled to the power switch device (203) in the switching power supply (201); and generating the fault signal in response to the voltage across the resistor (204) exceeding a third threshold.

Technical Field

Embodiments of the present disclosure relate to a motor drive circuit system, and more particularly, to a circuit for protecting a switching power supply in a motor driver, an operating method.

Background

Motor drive circuitry such as an Adjustable Speed Drive (ASD) is one common type of circuitry used to regulate the speed of a motor. The motor drive circuitry typically includes a rectifier circuit, a dc link, a switched mode power supply, and an inverter circuit. The rectifier circuit typically comprises 4 or 6 diodes. The inverter circuit typically includes 6 pairs of Insulated Gate Bipolar Transistors (IGBTs) and diodes with a Pulse Width Modulated (PWM) output to control the speed of the motor. Switched Mode Power Supplies (SMPS), also known as switching power supplies, are typically connected to the dc link to provide auxiliary power to the system.

The motor drive circuitry also includes control logic. The control logic circuits typically include sensing components and a Micro Control Unit (MCU) for sensing, protection, control and user interface of signals throughout the system. Certain electrical safety standards (e.g., IEC/UL 61800-5-1) require adjustable speed drives to provide protection against electrical shock, thermal and energy hazards. Therefore, the switching power supply circuit generally has an isolated topology, such as a flyback switching power supply circuit. Flyback switching power supplies typically include a metal-oxide semiconductor field effect transistor (MOSFET) or IGBT switch and an isolated transformer. The transformer provides isolation between the primary side circuitry and the ultra low voltage (ELV) side output at well-designed intervals and/or solid insulation. The ELV side output provides available power for a user of the circuit.

Disclosure of Invention

Current safety standards require that the motor drive circuitry also be able to provide protection against electrical shock, thermal injury, and energy injury in a single fault condition. The single fault condition includes a short circuit of a diode of the rectifier circuit, a short circuit of a switch (e.g., MOSFET) in the switching power supply, or a short circuit of a switch in the inverter circuit. However, there is currently no effective means to monitor the occurrence of such single fault conditions in switching power supplies, particularly short-circuit failure faults of power switching devices in switching power supply circuits. The present disclosure provides a circuit for a switching power supply in a motor drive to address, or at least partially address, the above-mentioned problems, or other potential problems, in conventional switching power supply circuits.

In a first aspect of the disclosure, a circuit for a switching power supply in a motor driver is provided. The circuit includes a detection circuit coupled to the switching power supply and configured to detect a short circuit failure of a power switching device in the switching power supply and generate a fault signal in response to detecting the short circuit failure; and a controller coupled to the detection circuit and configured to short circuit an inverter circuit in the motor drive in response to receiving the fault signal.

By using the circuit according to the embodiment of the disclosure, the state of the power switch device in the switching power supply circuit can be obtained, and the response can be made at the first time under the condition that the power switch device is short-circuited and fails, so that the safety of the switching power supply circuit and even the whole motor driver is improved by short-circuiting the inverter circuit.

In some embodiments, the detection circuit is further configured to detect a trigger voltage between the control terminal and the second terminal and an off-voltage of the first terminal and the second terminal of the power switching device in the switching power supply circuit; and generating a fault signal in response to the trigger voltage being below a first threshold and the cutoff voltage being below a second threshold. According to the characteristics of a power switching device such as a MOSFET, a fault signal is issued by detecting whether both a trigger voltage and a cut-off voltage are simultaneously below a threshold value, thereby detecting a short circuit fault of the power switching device in a simple and efficient manner.

In some embodiments, the detection circuit is further configured to: detecting a voltage across a resistor coupled to a power switch in a switching power supply circuit; and generating a fault signal in response to the voltage across the resistor exceeding a third threshold. The method can detect the short-circuit fault on the power switch device under the condition of not increasing the circuit topology as much as possible, thereby improving the system safety.

In some embodiments, the detection circuit includes a first comparison circuit coupled to the power switch and configured to generate a first electrical signal based on the received cutoff voltage and a reference voltage; a second comparison circuit coupled to the power switch and configured to generate a second electrical signal based on the received trigger voltage and the reference voltage; and a third comparison circuit coupled to the first and second comparison circuits and configured to generate a fault signal based on the first and second electrical signals. In this way, detection of a short-circuit fault on the power switching device is achieved by a simple circuit.

In some embodiments, the first comparison circuit comprises: a first voltage dividing circuit configured to divide the off-voltage into a first voltage; and a first comparator having an inverting input coupled to the first voltage divider circuit to receive the first voltage and configured to generate a first electrical signal based on the first voltage and a reference voltage.

In some embodiments, the second comparison circuit comprises: a second voltage division circuit configured to divide the trigger voltage into a second voltage; and a second comparator having an inverting input coupled to the second voltage dividing circuit to receive the second voltage and configured to generate a second electrical signal based on the second voltage and the reference voltage.

In some embodiments, the reference voltage is an average of the first voltage and the second voltage.

In some embodiments, the third comparison circuit comprises: an RC circuit coupled to the output of the first comparator and the second comparator; a third comparator, an inverting input of the third comparator coupled to the RC circuit to receive the RC voltage; and a feedback circuit coupled between the non-inverting input of the third comparator and the output of the third comparator to provide a feedback voltage to the non-inverting input of the third comparator.

In some embodiments, the feedback circuit is configured to generate the fault signal in response to the cutoff voltage and the trigger voltage becoming the same potential such that the feedback voltage is lower than the RC voltage. In this way, the fault signal can be output in a mode that the third comparator outputs a low level, so that the fault signal can be applied to a controller, and the flexibility of control is improved.

In some embodiments, the RC circuit includes a first resistor having a first end coupled to the voltage source; a capacitor between the second terminal of the first resistor and ground; a second resistor having a first end coupled to the output of the first comparator and a second end coupled to the second end of the first resistor and the inverting input of the third comparator; and a third resistor, a first end of the third resistor being coupled to the output of the second comparator, and a second end of the third resistor being coupled to the second end of the first resistor and the inverting input of the third comparator. By arranging the RC circuit, a delay difference between the trigger voltage and the off-voltage can be eliminated, thereby making the detection more accurate.

In a second aspect of the disclosure, a motor drive circuit system is provided. The system comprises a rectifying circuit coupled to a power supply for rectifying an input electrical signal for output; a switching power supply circuit coupled to an output of the rectifier circuit and comprising a circuit according to the first aspect hereinbefore; and an inverter circuit coupled to the rectifier circuit for outputting the electrical signal to drive the motor.

In a third aspect of the present disclosure, a method of operating a switching power supply circuit for a motor driver is provided. The method includes receiving a fault signal from a detection circuit coupled to the switching power supply circuit, wherein the detection circuit is to detect a short circuit failure of a power switching device in the switching power supply and to generate the fault signal in response to detecting the short circuit failure; and short circuiting an inverter circuit in the motor driver in response to receiving the fault signal.

In some embodiments, receiving the fault signal includes: receiving a fault signal from a detection circuit coupled to the power switching device, wherein the detection circuit is configured to: detecting a trigger voltage between a control terminal and a second terminal of a power switch device in a switching power supply circuit and an off-voltage of the first terminal and the second terminal; and generating a fault signal in response to the trigger voltage being below a first threshold and the cutoff voltage being below a second threshold.

In some embodiments, receiving the fault signal includes: receiving a fault signal from a detection circuit coupled to the power switching device, wherein the detection circuit is configured to: detecting a voltage across a resistor coupled to a power switch in a switching power supply circuit; and generating a fault signal in response to the voltage across the resistor exceeding a third threshold.

It should be understood that this summary is not intended to identify key or essential features of the embodiments of the disclosure, nor is it intended to be used to limit the scope of the disclosure. Other features of the present disclosure will become readily apparent from the following description.

Drawings

The above and other objects, features and advantages of the present disclosure will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout the exemplary embodiments of the present disclosure.

FIG. 1 shows a schematic diagram of a conventional motor drive circuitry;

FIG. 2 shows a schematic diagram of motor drive circuitry according to an embodiment of the present disclosure;

fig. 3 shows a schematic diagram of a switching power supply according to an embodiment of the present disclosure;

fig. 4 shows a schematic diagram of a switching power supply according to another embodiment of the present disclosure;

FIG. 5 shows an electrical signal schematic of a circuit to detect a short circuit fault from a cutoff voltage and a trigger voltage according to an embodiment of the present disclosure;

FIG. 6 shows an electrical signal schematic of a circuit to detect a short circuit fault from a voltage across a resistor coupled to a power switching device, according to an embodiment of the present disclosure; and

fig. 7 shows a flow chart of a method of operating a switching power supply for a motor drive.

The same or similar reference numbers will be used throughout the drawings to refer to the same or like elements.

Detailed Description

The present disclosure will now be described with reference to several example embodiments. It should be understood that these examples are described only for the purpose of enabling those skilled in the art to better understand and thereby enable the present disclosure, and are not intended to set forth any limitations on the scope of the technical solutions of the present disclosure.

As used herein, the term "include" and its variants are to be read as open-ended terms meaning "including, but not limited to. The term "based on" will be read as "based at least in part on". The terms "one embodiment" and "an embodiment" should be understood as "at least one embodiment". The term "another embodiment" should be understood as "at least one other embodiment". The terms "first," "second," and the like may refer to different or the same object. Other explicit and implicit definitions may be included below. The definitions of the terms are consistent throughout the specification unless the context clearly dictates otherwise.

Motor drivers are common circuitry used to drive motors and to enable adjustment of the motor speed. One common motor drive is, for example, an Adjustable Speed Drive (ASD). The motor drive circuitry will be described below primarily with respect to an adjustable speed drive as an example. It should be understood that the circuit according to embodiments of the present disclosure is not only applicable to adjustable speed drives, but may also be applicable to other suitable motor drives.

Fig. 1 shows a schematic diagram of motor drive circuitry in accordance with an embodiment of the present disclosure. The general circuit topology of the adjustable speed drive can also be seen in fig. 1. As shown in fig. 1, the adjustable speed drive generally includes a rectifier circuit 205, an inverter circuit 202, a dc link 206, and a Switched Mode Power Supply (SMPS). The rectifying circuit 205 generally includes 4 or 6 diodes depending on the input phase of the power supply 207. A branch protection device is generally provided between the power supply 207 and the rectifier circuit 205.

The inverter circuit 202 generally includes 6 pairs of Insulated Gate Bipolar Transistors (IGBTs) and diodes. The inverter circuit 202 is used for Pulse Width Modulation (PWM) output to drive the motor 208 and control the rotational speed of the motor 208. A Switched Mode Power Supply (SMPS), also known as switching power supply 201', is typically connected to the dc link to provide auxiliary power to the system.

The motor drive circuitry also includes control logic. The control logic circuitry typically includes a sensing component and a Micro Control Unit (MCU) or controller 103' for sensing, protection, control and user interface of signals throughout the system. Adjustable speed drives typically need to meet certain electrical safety standards in order to be allowed to market. Electrical safety standards typically impose stringent requirements and test guidelines on the performance indicators of the adjustable speed drive.

For example, certain electrical safety standards (e.g., IEC/UL 61800-5-1) require adjustable speed drives to provide protection against electrical shock, thermal hazards, and energy hazards. In particular, some safety standards require adjustable speed drives to be able to provide protection against electric shock, thermal and energy hazards under single fault conditions. The single fault condition includes a short circuit of a diode in the rectifying circuit 205, a short circuit of a power switch in the inverter circuit 202, or a short circuit of a power switch in the switching power supply.

To meet the requirements of safety standards, switching power supply circuits typically have an isolated topology, such as a flyback switching power supply circuit. Flyback switching power supplies typically include a metal-oxide semiconductor field effect transistor (MOSFET) or IGBT switch and an isolated transformer. The transformer provides isolation between the primary side circuitry and the ultra low voltage (ELV) side output at well-designed intervals and/or solid insulation. The ELV side output provides available power for a user of the circuit.

To pass the safety standard, a "component failure test" must be performed under a single failure condition in accordance with the test criteria in the safety standard to verify safety. Tests that can pass safety standards include no flame or molten metal or spark ignition of the surgical cotton indicator, and the voltage of the ELV circuit must not be above a specified threshold during/after the test.

In case of a short circuit of the power switching device of the switching power supply 201', energy is typically discharged in the loop of the switching power supply, causing an arc, a spark, etc. Meanwhile, if the insulation layer of the transformer of the switching power supply 201' is damaged during a fault, the ELV side voltage may also exceed an allowable safety level.

To meet this specification, current adjustable speed drives typically have an improved housing for the adjustable speed drive to contain the flame or molten metal or spark within the adjustable speed drive. Conventional such improvements are typically used to address all three of the above mentioned types of component failures: a short circuit occurs in a diode in the rectifier circuit 205, a short circuit occurs in a power switch in the inverter circuit 202, or a short circuit occurs in a power switch in the switching power supply. In the event of a short circuit of a power switch in a switching power supply, it is also often necessary to repeatedly design the transformer winding structure in the switching power supply to maintain insulation during a fault.

It can be seen that the conventional method of such improvement is to redesign the mechanical structure or to redesign the transformer in the switching power supply to make the motor driver meet the standard requirements. Embodiments of the present disclosure provide a circuit for a switching power supply in a motor drive, such as an adjustable speed drive, that is capable of diverting a short circuit failure fault of a power switching device in the switching power supply into an inverter circuit to solve, or at least partially solve, the above-described problems and/or other potential problems in conventional motor drives. Some example embodiments will now be described with reference to fig. 2 to 7.

Fig. 2 shows a schematic diagram of motor drive circuitry 200 according to an embodiment of the present disclosure. As shown in fig. 2, generally, a circuit according to an embodiment of the present disclosure includes a detection circuit 101 and a controller 103. Wherein the controller 103 may be independent of its own controller in the motor drive circuit. That is, the controller 103 may be different from a controller for controlling a motor driver among the motor drivers. Of course, in some embodiments, the controller 103 may be a controller for controlling a motor drive.

The detection circuit 101 is coupled to the switching power supply 201, and is capable of detecting a short-circuit failure of the power switching device 203 in the switching power supply 201 and generating a fault signal according to the short-circuit failure. Short circuit failure may be due to damage to the device. As mentioned above, if the short circuit failure is not handled in time, a greater accident may occur and affect the safety of the motor drive.

In some embodiments, the power switching device 203 in the switching power supply 201 may include a metal-oxide semiconductor field effect transistor (MOSFET). The power switch device 203 will be described below mainly by taking a MOSFET as an example. However, it should be understood that the circuit according to embodiments of the present disclosure may be equally applied to power switching devices having similar principles. For example, in some alternative embodiments, the power switching device 203 may include an IGBT switch.

As shown in fig. 2, the controller 103 is coupled to the detection circuit 101 and is capable of controlling the inverter circuit 202 in the motor driver to be short-circuited in response to receiving a fault signal from the detection circuit 101. Shorting the inverter circuit 202 can increase the current in the rectifier circuit or branch protection device. The current increase exceeding a certain threshold value may blow a protection device in the rectifier circuit and/or blow a protection device (e.g. a fuse) in a branch protection between the grid and the motor driver, thereby disconnecting the grid and the motor driver and preventing further inrush of energy from the grid. In addition, shorting inverter circuit 202 also provides a bleed path for the energy stored in the DC link, thereby improving system safety.

Fig. 2 shows a case where the controller 103 short-circuits the inverter circuit 202. In general, short-circuiting the inverter circuit 202 means that at least one arm of the inverter circuit is short-circuited (for example, by activating an IGBT switch of at least one arm to be on), so that an energy discharge path can be transferred from the switching power supply to the inverter circuit and/or the rectifier circuit, and a branch protection device at the front end of the motor driver or a protection device in the rectifier circuit is triggered to be fused, thereby causing a disconnection of the entire motor driver. In this way, the security of the system is improved. Meanwhile, the inverter circuit 202 short circuit can release energy in the DC link to prevent the energy from entering the switching power supply, so that the safety of the switching power supply and even the whole motor driver is improved.

By the circuit according to the embodiment of the disclosure, short-circuit faults of the power switching devices in the switching power supply can be transferred to the inverter circuit. In other words, the circuit is able to actively cut off the connection of the motor drive to the grid and simultaneously provide an energy bleed path in the dc link by short-circuiting the inverter circuit 202 in case of a short-circuit fault of the power switching device 203. This can effectively improve the safety of the motor driver so that the motor driver can easily pass the test of the safety standard.

How to detect a short circuit failure in the power switching device 203 by the detection circuit 101 is described below. As shown in fig. 3, in some embodiments, the detection circuit 101 is capable of detecting a voltage between the control terminal G of the power switch device 203 and one of the other two terminals and between the two terminals other than the control terminal G. For convenience of the following description, the two terminals except the control terminal G are referred to as a first terminal S and a second terminal D, respectively.

In the embodiment corresponding to the power switch device 203 being a MOSFET device, the control terminal G refers to the gate of the MOSFET, the first terminal S corresponds to the source and the second terminal corresponds to the drain. Of course, it should be understood that in case the power switch device 203 belongs to another transistor, the control terminal G, the first terminal S and the second terminal D may also refer to the corresponding terminals of the transistor, respectively. The other transistors are similar to MOSFETs, and the respective terminals of the MOSFETs will be described as examples.

The detection circuit 101 is able to detect a trigger voltage V between the control terminal G and the second terminal D_GDAnd a cut-off voltage V between the first terminal S and the second terminal D_DS. Under normal operation of the power switch device 203, at the trigger voltage, at V_GDIn the case of the high level, the power switch device 203 is in the on state, and therefore, the off voltage V_DSAt a low level as shown in fig. 5.

On the contrary, at the trigger voltage V_GDIn the case of low level, the power switch device 203 is in an off state, and therefore, the off voltage V_DSAt a high level. If the power switch device 203 is short-circuited, then the trigger voltage V is set_GDAt low level, a cut-off voltage V occurs_DSIn the low level case, that is, the power switch device 203 is erroneously turned on. At this time, the detection circuit 101 can respond to the trigger voltage V_GDAnd a cut-off voltage V_DSBelow a certain threshold a fault signal is generated.

Wherein the trigger voltage V_GDAnd a cut-off voltage V_DSThe threshold values below may be the same threshold value or different threshold values set respectively. That is, the detection circuit 101 may be at the trigger voltage V_GDBelow a first threshold value and a cut-off voltage V_DSA fault signal is generated below a second threshold. This way, the failure can be avoidedThe first time of occurrence generates a fault signal to realize short circuit of the inverter circuit, thereby improving the safety of the motor driver.

To achieve the above functionality, in some embodiments, the detection circuit 101 may include three comparison circuits, as shown in fig. 3. For convenience of description, the three comparison circuits are hereinafter referred to as a first comparison circuit, a second comparison circuit, and a third comparison circuit, respectively. The first comparison circuit is coupled to the power switch 203 and can be based on the received trigger voltage V_GDAnd a reference voltage V_refAnd generates a first electrical signal. The second comparison circuit is coupled to the power switch 203 and can be based on the received off-voltage V_DSAnd a reference voltage V_refAnd a second electrical signal is generated.

The third comparison circuit is coupled to the outputs of the first and second comparison circuits and is capable of generating a fault signal based on the first electrical signal and the second electrical signal. For example, at a trigger voltage V_GDAnd a cut-off voltage V_DSWhen the voltage is lower than the predetermined threshold, the first and second electric signals output from the first and second comparison circuits are low-level signals, respectively. The third comparison circuit can output a low level signal (i.e., a fail signal) according to the low level signal. The controller 103 can know that the power switch device 203 is in a fault state according to the low-level signal output by the third comparing circuit, so as to trigger the short circuit of the inverter circuit. The circuit according to the embodiment of the present disclosure can realize the detection of the malfunction and the action of the power switching device 203 with the above-described simple circuit, improving the safety of the system in a cost-effective manner.

In some embodiments, the first comparison circuit may include a voltage divider circuit and a comparator. For convenience of description, a voltage dividing circuit of the first comparison circuit is referred to as a first voltage dividing circuit 1012, and a comparator is referred to as a first comparator 1014. The first voltage dividing circuit 1012 can divide the cut-off voltage V_DSThe voltage is divided into a first voltage. The inverting input of the first comparator 1014 is coupled to the first voltage divider circuit and is capable of being responsive to the first voltage and a reference voltage V_refAnd generates a first electrical signal.

Similarly, the second comparison circuit may also include a second voltage division circuit 1013 and a second comparator 1015. The second voltage divider 1013 can divide the trigger voltage V_GDThe voltage is divided into a second voltage. The inverting input of the second comparator 1015 is coupled to the second voltage divider circuit and is capable of being responsive to the second voltage and a reference voltage V_refAnd a second electrical signal is generated.

It should be understood that the reference voltage V_refAre input to the non-inverting inputs of the first comparator 1014 and the second comparator 1015. In some embodiments, the reference voltage V_refMay be an average of the first voltage and the second voltage. Of course, in some alternative embodiments, the reference voltage V_refOther values that facilitate comparison of the first and second voltages are also possible.

In some embodiments, the third comparison circuit includes an RC circuit, a third comparator 1016, and a feedback circuit 1017. An RC circuit is coupled to the output terminals of the first comparator 1014 and the second comparator 1015 for eliminating the trigger voltage V_GDAnd a cut-off voltage V_DSAnd the signal delay between them, thereby making the detection more accurate. The inverting input of the third comparator 1016 is coupled to the RC circuit to receive the RC voltage processed by the RC circuit.

In some embodiments, as shown in fig. 3, the RC circuit may include a plurality of resistors and capacitors C. The plurality of resistors includes a first resistor R1, a second resistor R2, and a third resistor R3. A first end of the first resistor R1 is coupled to a voltage source Vcc. A first end of a second resistor R2 is coupled to the output of the first comparator 1014 and a second end is coupled to the second segment of the first resistor R1 and the inverting input of the third comparator 1016. A first end of the third resistor R3 is coupled to the output of the second comparator 1015, and a second end is coupled to the second segment of the first resistor R1 and the inverting input of the third comparator 1016. The capacitor C is coupled between the first resistor R1 and ground. In this way, an RC circuit is implemented to trigger the voltage V_GDAnd a cut-off voltage V_DSThe signal delay therebetween is eliminated.

The feedback circuit 1017 is coupled to the third comparator 1016 and the same phaseBetween the input and output to provide a feedback voltage to the non-inverting input of the third comparator 1016. The feedback circuit 1017 is capable of responding to the cutoff voltage V_DSAnd a trigger voltage V_GDBecomes the same phase (i.e., low) such that the feedback voltage is lower than the RC voltage to cause the third comparator 1016 to output a fault signal.

To achieve the above functionality, in some embodiments, the feedback circuit 1017 may include a plurality of resistors. For convenience of context, the plurality of resistors herein are referred to as a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, and a seventh resistor R7, respectively. A fourth resistor R4 is coupled between the output of the third comparator 1016 and the voltage source Vcc. The fifth resistor R5 and the sixth resistor R6 are coupled in series between the voltage source Vcc and ground, respectively. A first end of the seventh resistor R7 is coupled to the fifth and sixth resistors R5 and R6 and the non-inverting input of the third comparator 1016, and a second end is coupled to the output of the third comparator 1016.

In this way, by setting the resistance values of the fourth resistor R4, the fifth resistor R5, the sixth resistor R6, and the seventh resistor R7, respectively, it is achieved that the feedback voltage is lower than the RC voltage. Such a circuit enables the required functions to be implemented in a cost-effective manner, reducing costs and improving the accuracy of the detection. In addition, the feedback circuit 1017 enables the third comparator circuit to perform a hysteresis comparison function.

The comparison circuit with the hysteresis comparison function can accelerate the response speed and improve the anti-interference capability of the comparison circuit. For example, when triggering voltage V_GDBelow a first threshold value and a cut-off voltage V_DSBelow the second threshold (i.e., a short-circuit failure condition), the output of the third comparator 1016 changes from high to low. At this time, if the input of the third comparator 1016 fluctuates within a certain range, the output of the third comparator 1016 is always maintained at a low level, so that the third comparator 1016 forms a monostable flip-flop, thereby effectively improving the anti-interference capability and improving the detection accuracy.

The foregoing description is by way of example onlyBy detecting the cut-off voltage V across the power switch device 203_DSAnd a trigger voltage V_GDTo detect an embodiment of a short circuit failure of the power switch device 203. Of course, it should be understood that these examples are illustrative only and are not intended to limit the scope of the present disclosure. Any other suitable means or manner is also possible.

For example, in some alternative embodiments, the short circuit failure may also be detected by detecting the maximum current on the input side of the transformer of the switching power supply 201. The maximum current or peak current may be calculated from the dc link voltage minimum and the maximum load of the switching power supply. The peak current is generally less than the saturation current of the input side of the transformer of the switching power supply 201. When it is detected that the current on the input side of the transformer of the switching power supply 201 is greater than the peak current and the saturation current, a short-circuit failure occurs on the power switching device, and the controller 103 may issue a fault signal.

In some embodiments, the current on the input side of the transformer may be realized by means of a voltage coupled to a resistor 204 on the power switch 203. The voltage across the resistor 204 is generally the product of the current on the input side and the resistance of the resistor 204. For example, in a normal operating state of the power switch device 203, the voltage across the resistor 204 generally fluctuates with a certain waveform in a range below a certain threshold (for convenience of description, will be referred to as a third threshold hereinafter). In some embodiments, the third threshold may generally be a product of the saturation current or the peak current of the input side of the transformer and the resistance value of the resistor in the above-mentioned switching power supply. When the power switch device 203 fails due to a short circuit, the voltage across the resistor 204 exceeds the third threshold due to an increase in current thereon, as shown in fig. 6.

In these embodiments, the detection circuit 101 can detect the voltage across the resistor 204 and can output a fault signal in response to the voltage exceeding a third threshold. It should be understood that the detection circuit 101 in these embodiments may be part of the controller 103 or may be said to be integrated in the controller 103. That is, the controller 103 may generate a fault signal according to the voltage across the resistor 204 exceeding the third threshold and short the inverter circuit 202 according to the fault signal.

In some embodiments, the function of comparing the voltage across the resistor 204 with the third threshold may also be implemented by a simple comparison circuit or comparator. For example, in some embodiments, a comparison circuit or comparator may be coupled to the controller 103 or integrated in the controller 103 to output a low level signal to cause the controller 103 to trigger the inverter circuit 202 to short circuit when the voltage on the resistor 204 is above the third threshold.

In some embodiments, the above-described function of detecting the voltage across the resistor 204 and then comparing with the third threshold value may also be implemented by adjusting only the logic circuit of the controller 103, without arranging other additional circuits. For example, in some embodiments, the controller 103 may be coupled to the resistor 204 directly or indirectly (e.g., through additional detection circuitry 101) to obtain the voltage across the resistor 204. And the controller 103 can output a fault signal according to the voltage exceeding the third threshold. This approach simplifies the circuit topology of the motor drive and thus reduces the cost of the motor drive.

Of course, it should be understood that the manner in which the voltage across resistor 204 is measured is merely one exemplary embodiment of measuring the input-side current and is not intended to limit the scope of the present disclosure. Any other suitable measurement is possible. For example, in some alternative embodiments, the current on the input side may be directly measured and the short circuit failure of the power switching device may be determined based on the current exceeding the saturation current or the peak current.

A motor drive circuitry 200 is also disclosed according to another aspect of the present disclosure. As shown in fig. 2, the motor drive circuit system 200 includes a rectifier circuit 205, a dc link 206, a switching power supply 201, and an inverter circuit 202. The rectifying circuit 205 is coupled to a power supply for rectifying an input electrical signal for output. The switching power supply 201 comprises a circuit for protecting the switching power supply 201 according to the above description. The inverter circuit 202 is coupled to the rectifier circuit 205 and is capable of outputting an electrical signal to drive the motor. The controller 103 in the above-described circuit for protecting the switching power supply 201 (as described above, the controller 103 may also be a controller of the motor drive circuit system 200) may short-circuit the inverter circuit 202 in accordance with receiving the fault signal.

There is also provided, in accordance with another aspect of the present disclosure, a method 700 of operating a switching power supply for a motor drive. Fig. 7 shows a flow chart of a method of operating a switching power supply for a motor drive. As shown in fig. 7, at 710, a fault signal is received from a detection circuit 101 coupled to the switching power supply 201, wherein the detection circuit 101 is configured to detect a short circuit failure of a power switching device 203 in the switching power supply 201 and generate the fault signal in response to detecting the short circuit failure.

At 720, an inverter circuit in the motor drive is shorted in response to receiving the fault signal. The operating method may be stored in the memory in the form of a computer program for execution by the controller or a separate controller in the motor drive circuitry 200 to perform the above-described method.

It is to be understood that the above detailed embodiments of the disclosure are merely illustrative of or explaining the principles of the disclosure and are not limiting of the disclosure. Therefore, any modification, equivalent replacement, and improvement made within the spirit and principle of the present disclosure should be included in the protection scope of the present disclosure. Also, it is intended that the appended claims cover all such changes and modifications that fall within the true scope and range of equivalents of the claims.