Flyback circuit and motor control circuit

Abstract

The utility model provides a flyback circuit and a motor control circuit, the flyback circuit comprises a rectification filtering module, a transformer, an output module, a control module and a feedback module, the transformer comprises a primary winding and a secondary winding; a first end of the output module is connected with a secondary winding of the transformer, a second end of the output module is connected with the feedback module, and the feedback module is connected with the control module; the feedback module comprises an isolation optocoupler, a comparison unit and a pull-up unit; a first input end of the comparison unit is connected with the output module, a second input end of the comparison unit is used for accessing a reference voltage, an output end of the comparison unit is connected with the isolation optocoupler through the pull-up unit, and the reference voltage is greater than or equal to 0. The feedback module is connected with the control module to control the storage and release of the magnetic field energy in the transformer, so that the output voltage of the output module is adjusted, the output voltage reaches the required voltage value, the stable output voltage is provided, an additional circuit structure does not need to be added, the circuit structure is simple, and the cost is reduced.

Description

Technical Field

[0001] This application relates to the field of power supplies, and particularly to a flyback circuit and a motor control circuit. Background Art

[0002] The flyback circuit is a common switching power supply topology, widely used in power adapters, chargers, and low-power power supplies. It realizes the transfer and conversion of electrical energy through the storage and release of magnetic field energy in the transformer, and outputs a stable voltage. In the industry, it is very difficult to develop a switching power supply with a large AC voltage input (such as AC100V~AC240V), an ultra-low voltage output (such as 0V), and a continuously adjustable output voltage.

[0003] The solutions in the prior art cannot achieve the required output voltage value and cannot meet some application scenarios; if you want to output the required voltage value, additional circuit structures need to be added, which will increase the cost.

[0004] The foregoing description is provided to give general background information and does not necessarily constitute prior art. Summary of the Utility Model

[0005] This application provides a flyback circuit and a motor control circuit to solve the problem that the output voltage in the prior art cannot reach the required voltage value.

[0006] In a first aspect, this application provides a flyback circuit, including: a rectification and filtering module, a transformer, an output module, a control module, and a feedback module. The transformer includes a primary winding and a secondary winding;

[0007] The input end of the rectification and filtering module is connected to alternating current, the output end of the rectification and filtering module is connected to the first end of the primary winding of the transformer, the third end of the rectification and filtering module is connected to the second end of the primary winding through the control module, and the third end of the rectification and filtering module is grounded;

[0008] The first end of the output module is connected to the secondary winding of the transformer, the second end of the output module is connected to the feedback module, and the feedback module is connected to the control module;

[0009] The feedback module includes an isolation optocoupler, a comparison unit, and a pull-up unit; the first input end of the comparison unit is connected to the output module, the second input end of the comparison unit is used to access a reference voltage, the output end of the comparison unit is connected to the isolation optocoupler through the pull-up unit, and the reference voltage is greater than or equal to 0.

[0010] In one embodiment, the isolation optocoupler outputs a first signal when the comparison unit detects that the output voltage of the output module is greater than the reference voltage, and the isolation optocoupler outputs a second signal when the comparison unit detects that the output voltage is less than or equal to the reference voltage;

[0011] The control module disconnects when receiving the first signal; the control module conducts when receiving the second signal.

[0012] In one embodiment, the feedback module further includes an adjustable voltage unit, and the adjustable voltage unit is connected to the second input terminal of the comparison unit;

[0013] The adjustable voltage unit is used to generate a reference voltage.

[0014] In one embodiment, the adjustable voltage unit includes a first voltage-dividing resistor and a second voltage-dividing resistor;

[0015] The first end of the first voltage-dividing resistor is connected to the first power supply, the second end of the first voltage-dividing resistor is connected to the first end of the second voltage-dividing resistor, and the second end of the second voltage-dividing resistor is grounded;

[0016] The output terminal of the second voltage-dividing resistor is connected to the second input terminal of the comparison unit.

[0017] In one embodiment, the adjustable voltage unit further includes a voltage regulator or a third resistor;

[0018] The voltage regulator or the third resistor is connected in parallel with the second voltage-dividing resistor.

[0019] In one embodiment, the second voltage-dividing resistor is an adjustable resistor.

[0020] In one embodiment, the pull-up unit includes a fourth resistor, and the first end of the fourth resistor is connected to the first power supply, and the second end of the fourth resistor is connected to the isolation optocoupler and the comparison unit.

[0021] In one embodiment, the flyback circuit further includes an isolated power supply, and the isolated power supply is connected to the rectification and filtering module for outputting the first power supply.

[0022] In one embodiment, the feedback module further includes a voltage-dividing unit, and the voltage-dividing unit includes a fifth resistor and a sixth resistor;

[0023] The first end of the fifth resistor is connected to the output module, and the second end of the fifth resistor is connected to the first end of the sixth resistor;

[0024] The first end of the sixth resistor is connected to the first input terminal of the comparison unit, and the second end of the sixth resistor is grounded.

[0025] In one embodiment, the output module includes a first diode, a second capacitor, and a load;

[0026] The anode of the first diode is connected to the first end of the secondary winding, and the cathode of the first diode is connected to the first end of the second capacitor and the first end of the load;

[0027] The second end of the second capacitor is connected to the second end of the secondary winding, and the second end of the load is grounded.

[0028] In a second aspect, the present application provides a motor control circuit, including a flyback circuit as described in any one of the above.

[0029] The present application provides a flyback circuit, including: a rectifying and filtering module, a transformer, an output module, a control module, and a feedback module. The transformer includes a primary winding and a secondary winding; a first end of the rectifying and filtering module is connected to alternating current, a second end of the rectifying and filtering module is connected to a first end of the primary winding of the transformer, a third end of the rectifying and filtering module is connected to a second end of the primary winding through the control module, and the third end of the rectifying and filtering module is grounded; a first end of the output module is connected to the secondary winding of the transformer, a second end of the output module is connected to the feedback module, and the feedback module is connected to the control module; the feedback module includes an isolation optocoupler, a comparison unit, and a pull-up unit; a first input end of the comparison unit is connected to the output module, a second input end of the comparison unit is used for accessing a reference voltage, an output end of the comparison unit is connected to the isolation optocoupler through the pull-up unit, and the reference voltage is greater than or equal to 0. The present application controls the storage and release of magnetic field energy in the transformer through the connection between the feedback module and the control module, and further adjusts the output voltage of the output module, so that the output voltage reaches the required voltage value, provides a stable output voltage, does not require adding an additional circuit structure, has a simple circuit structure, and reduces costs. Description of the Drawings

[0030] The drawings herein are incorporated into the specification and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0031] Figure 1 Schematic structural diagram of a flyback circuit provided by an embodiment of the present application;

[0032] Figure 2 Schematic structural diagram of a feedback module provided by an embodiment of the present application;

[0033] Figure 3 Schematic structural diagram of a feedback module provided by another embodiment of the present application;

[0034] Figure 4 Schematic structural diagram of a feedback module provided by an embodiment of the present application;

[0035] Figure 5 Schematic structural diagram of a feedback module provided by an embodiment of the present application;

[0036] Figure 6 Schematic structural diagram of a feedback module provided by another embodiment of the present application;

[0037] Figure 7 Schematic structural diagram of an isolated power supply provided by an embodiment of the present application.

[0038] Reference numerals:

[0039] 110, rectification and filtering module; 120, transformer; 130, output module; 140, control module; 150, feedback module; 151, comparison unit; 152, pull-up unit; 153, isolation optocoupler; 154, adjustable voltage unit; R1, first voltage-dividing resistor; R2, second voltage-dividing resistor; R3, third resistor; R4, fourth resistor; R5, fifth resistor; R6, sixth resistor; U5, voltage regulator.

[0040] Through the above-mentioned drawings, specific embodiments of the present application have been shown, and more detailed descriptions will be given later. These drawings and textual descriptions are not intended to limit the scope of the concept of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. Detailed description of the specific embodiments

[0041] Here, the exemplary embodiments will be described in detail, and the examples are shown in the drawings. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0042] The flyback circuit is a common switching power supply topology, widely used in power adapters, chargers, and low-power power supplies. It realizes the transfer and conversion of electrical energy through the storage and release of magnetic field energy in the transformer, and outputs a stable voltage. However, at present, the output voltage of the flyback circuit cannot reach the required output voltage value; if the required voltage value is to be output, an additional circuit structure needs to be added, increasing the cost.

[0043] Based on the above problems, the present application provides a flyback circuit, as Figure 1 shown Figure 1 is a schematic structural diagram of a flyback circuit provided by an embodiment of the present application, including: a rectification and filtering module 110, a transformer 120, an output module 130, a control module 140, and a feedback module 150. The transformer 120 includes a primary winding and a secondary winding;

[0044] The first end of the rectification and filtering module 110 is connected to alternating current, the second end of the rectification and filtering module 110 is connected to the first end of the primary winding of the transformer 120, the third end of the rectification and filtering module 110 is connected to the second end of the primary winding through the control module 140, and the third end of the rectification and filtering module 110 is grounded;

[0045] The first end of the output module 130 is connected to the secondary winding of the transformer 120, the second end of the output module 130 is connected to the feedback module 150, and the feedback module 150 is connected to the control module 140.

[0046] In this application, the feedback module 150 is connected to the control module 140 to control the storage and release of magnetic field energy in the transformer 120, thereby regulating the output voltage of the output module 130 to make the output voltage reach the required voltage value, providing a stable output voltage, without adding an additional circuit structure, with a simple circuit structure and reduced cost; secondly, this application can output multiple voltage levels and provide a stable low-voltage power supply.

[0047] The flyback circuit provided in this application is only one embodiment, and the feedback module 150 in this application can also be applied to other voltage conversion circuits, voltage control circuits or voltage protection circuits to provide a stable voltage.

[0048] In one embodiment, the control module 140 includes a controller and a switching transistor Q1. The first end of the switching transistor Q1 is connected to the second end of the primary winding of the transformer 120, the second end of the switching transistor Q1 is grounded, and the third end of the switching transistor Q1 is connected to the output end of the controller. In Figure 1 the embodiment, the switching transistor Q1 is an N-type MOS transistor, and the switching transistor Q1 can also be other types of switching transistors or switches, such as P-type MOS transistors, IGBTs, thyristors, etc., and this application does not limit this.

[0049] Specifically, the working principle of the flyback circuit: Refer to the appendix Figure 1, the L and N of the alternating current are rectified into direct current by the rectification and filtering module 110. The capacitor C1 filters the rectified direct current to remove the high-frequency part and provides a relatively smooth DC voltage. The direct current is sent to the transformer 120 and the switching transistor Q1. The polarities of the primary winding and the secondary winding of the transformer 120 are opposite, and the switching of Q1 is controlled by the controller to conduct and cut off. During the energy storage stage of the transformer 120, that is, the controller controls the switching transistor Q1 to conduct: when the switching transistor Q1 conducts, the DC voltage passes through the primary winding of the transformer 120, and the inductor current of the primary winding of the transformer 120 starts to rise, storing energy in the primary inductor of the transformer 120. Since the polarities of the primary winding and the secondary winding of the transformer 120 are opposite, the voltage on the secondary winding reverse-biases the diode D1 of the output module 130, and D1 is cut off; during this stage, the energy of the load R0 is provided by the output capacitor C2, and the output module 130 outputs a stable voltage Vout. During the energy release stage of the transformer 120, that is, the controller controls the switching transistor Q1 to cut off. When the switching transistor Q1 cuts off, the current in the primary winding rapidly decreases, causing a reverse voltage to be generated in the secondary winding. At this time, the voltage on the secondary winding forward-biases the diode D1 of the output module 130, and D1 conducts; the energy in the secondary winding of the transformer 120 is transferred to the load R0 through D1, and at the same time, the output capacitor C2 is charged to supplement the energy provided to the load in the previous stage. However, after adding the feedback module 150, the output voltage of the flyback circuit can be further controlled. The output voltage Vout of the output module 130 outputs a feedback signal to the control module 140 through the feedback module 150. The on and off times of the switching transistor in the control module 140 are controlled by the feedback signal output by the feedback module 150 to output the required voltage and maintain the stability of the output voltage; moreover, the feedback module 150 can control the flyback circuit to output multiple voltage levels.

[0050] In one embodiment, when the output voltage Vout of the output module 130 is less than or equal to the set value of the feedback module 150, the control module 140 outputs a control signal to control the switching transistor Q1 to conduct, increasing the energy storage and the output voltage Vout rises; when the output voltage Vout of the output module 130 is greater than the set value of the feedback module 150, the controller stops sending the control signal, the switching transistor Q1 remains in the cut-off state, stops the energy storage, and the output voltage Vout drops. Through this feedback mechanism, the flyback circuit in the present application controls the on and off times of the switching transistor Q1 to maintain the stability of the output voltage Vout.

[0051] During the process of conceiving the technical solution, the present application also provides a schematic structural diagram of a feedback module 150, as Figure 2As shown, the feedback module 150 includes a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, an isolation optocoupler U1, a third capacitor C3, and a voltage regulator U2. The first end of the seventh resistor R7 is connected to the output module 130 and the first end of the eighth resistor R8. The second end of the seventh resistor R7 is connected to pin 1 of the isolation optocoupler U1. The second end of the eighth resistor R8 is connected to the first end of the ninth resistor R9 and the second end of the third capacitor C3. The second end of the ninth resistor R9 is grounded. The first end of the voltage regulator U2 is connected to pin 2 of the isolation optocoupler U1 and the first end of the third capacitor C3. The second end of the voltage regulator U2 is grounded. The third end of the voltage regulator U2 is connected to the first end of the ninth resistor R9. Pin 3 of the isolation optocoupler U1 is grounded, and pin 4 of the isolation optocoupler U1 is connected to the control module 140.

[0052] Specifically, when the isolation optocoupler U1 is turned on, pins 3 and 4 of the isolation optocoupler U1 are connected, and pin 4 of the isolation optocoupler U1 is grounded, that is, the feedback signal output by the isolation optocoupler U1 to the control module 140 is at a low level. The controller in the control module 140 stops working, the switching transistor Q1 is turned off, and the output voltage Vout drops. When the isolation optocoupler U1 is turned off, pins 3 and 4 of the isolation optocoupler U1 are disconnected, the control module 140 works normally, and the control output voltage Vout rises to achieve voltage balance and output a relatively stable Vout. However, since the voltage regulator U2 is a reference source of 2.5V, the output voltage Vout is determined by the resistance values of the eighth resistor R8 and the ninth resistor R9, that is (unit: V). When the isolation optocoupler U1 works normally, the voltage between pins 1 and 2 of the isolation optocoupler U1 is at least 1.25V; the voltage between the first end and the second end of the voltage regulator U2 is at least 2.5V; therefore, the minimum value Vout.min of the output voltage of the output module 130 is: (unit: V). When the seventh resistor R7 is 0, the minimum value of the output voltage is 3.75V.

[0053] Figure 2 The provided feedback module 150 has the following disadvantages: The output voltage Vout of the flyback circuit is limited by the minimum value of 3.75V and cannot meet the voltage requirements of some low-voltage scenarios. If a lower required voltage value is to be output, additional circuits need to be added, such as adding an LDO circuit or a DC-DC circuit to convert the output voltage to the required voltage, but this will increase the cost and circuit area, and the accuracy of the output voltage is not high.

[0054] Therefore, as Figure 3 shown, Figure 3 is a schematic structural diagram of the feedback module 150 provided by another embodiment of the present application. The feedback module 150 includes an isolation optocoupler 153, a comparison unit 151, and a pull-up unit 152;

[0055] The first input terminal of the comparison unit 151 is connected to the output module 130. The second input terminal of the comparison unit 151 is used to access a reference voltage. The output terminal of the comparison unit 151 is connected to the isolation optocoupler 153 through the pull-up unit 152, and the reference voltage is greater than or equal to 0.

[0056] The isolation optocoupler 153 outputs a first signal when the comparison unit 151 detects that the output voltage is greater than the reference voltage, and the isolation optocoupler 153 outputs a second signal when the comparison unit 151 detects that the output voltage is less than or equal to the reference voltage; the control module 140 disconnects when receiving the first signal; the control module 140 conducts when receiving the second signal.

[0057] In this application, the control signal (the first signal or the second signal) output by the feedback module 150 is used to adjust the energy storage and release of the transformer 120, so as to control the output voltage. According to the need, the reference voltage can be input to precisely control the output voltage of the flyback circuit, enabling the flyback circuit to output the required voltage. Without adding additional circuits, stable voltage output can be achieved, and the accuracy of the output voltage can be improved.

[0058] Specifically, the isolation optocoupler 153 outputs a first signal when the comparison unit 151 detects that the output voltage is greater than the reference voltage. When the control module 140 receives the first signal, the connection between the second end of the primary winding of the transformer 120 and the ground wire is disconnected, causing the current in the primary winding to decrease. The voltage of the secondary winding forward-biases the diode D1 of the output module 130, and D1 conducts; the energy in the secondary winding of the transformer 120 is transferred to the load R through D1, and at the same time, the output capacitor C2 is charged, and the output voltage decreases; the isolation optocoupler 153 outputs a second signal when the comparison unit 151 detects that the output voltage is less than or equal to the reference voltage. When the control module 140 receives the second signal, it controls the second end of the primary winding of the transformer 120 to be grounded. At this time, the inductive current of the primary winding of the transformer 120 starts to rise. Since the polarities of the primary winding and the secondary winding of the transformer 120 are opposite, the voltage on the secondary winding reverse-biases the diode D1 of the output module 130, and D1 is cut off. The energy of the load R0 is provided by the output capacitor C2, and the output voltage increases. By introducing the reference voltage to control the output voltage required by the flyback circuit, the stability of the output voltage is achieved, and the accuracy of the output voltage is improved.

[0059] In one embodiment, as Figure 4 shown, Figure 4 is a schematic structural diagram of the feedback module 150 provided by an embodiment of this application. The feedback module 150 further includes an adjustable voltage unit 154, and the adjustable voltage unit 154 is connected to the second input terminal of the comparison unit 151; the adjustable voltage unit 154 is used to generate a reference voltage.

[0060] This application controls the flyback circuit to output voltages of different voltage levels by setting the adjustable voltage unit 154 to output different reference voltages, so as to meet various power supply voltage requirements. Without additional circuit design, it saves costs. Secondly, this application can also provide a stable voltage for the circuit, protect the circuit, and ensure the stable and reliable operation of the system.

[0061] In one embodiment, the adjustable voltage unit 154 includes a first voltage-dividing resistor R1 and a second voltage-dividing resistor R2 connected in series. The first end of the first voltage-dividing resistor R1 is connected to the first power supply, the second end of the first voltage-dividing resistor R1 is connected to the first end of the second voltage-dividing resistor R2, and the second end of the second voltage-dividing resistor R2 is grounded. The first end of the second voltage-dividing resistor R2 is connected to the second input terminal of the comparison unit 151.

[0062] In one embodiment, the second voltage-dividing resistor R2 is an adjustable resistor. The adjustable resistor can be a slide rheostat or a digital potentiometer.

[0063] In one embodiment, the pull-up unit 152 includes a fourth resistor. The first end of the fourth resistor is connected to the first power supply, and the second end of the fourth resistor is connected to the isolation optocoupler 153 and the comparison unit 151.

[0064] Specifically, when the voltage of the first power supply is 5V and the resistance value of the first voltage-dividing resistor R1 is 0Ω, the second input terminal Uin- of the comparison unit 151 can be transformed from 0V to 5V through the adjustable resistor, that is, the range of the reference voltage is 0V to 5V. The first input terminal Uin+ of the comparison unit 151 is the output voltage Vout. When Uin- of the comparison unit 151 is greater than or equal to Uin+, the output of the comparison unit 151 is low level. The current of the first power supply passes through the fourth resistor to the comparison unit 151, and the isolation optocoupler 153 is cut off. The pin 4 of the isolation optocoupler 153 is not grounded, and the control module 140 works normally to control the output voltage Vout of the flyback circuit to gradually increase. When the input terminal Uin- of the comparison unit 151 is less than Uin+, the output of the comparison unit 151 is NC (Not Connected), at this time, the current of the first power supply passes through the fourth resistor to the isolation optocoupler 153, the isolation optocoupler 153 conducts, and the pin 4 of the isolation optocoupler 153 is grounded, and the control module 140 stops working, and the output voltage Vout gradually decreases until the flyback circuit outputs a relatively stable Vout. When the output is stable, Since the input terminal Uin- of the comparison unit 151 can be transformed from 0V to 5V through the adjustable resistor, the range of the output voltage Vout can reach 0V to 5V.

[0065] In one embodiment, the adjustable voltage unit 154 further includes a voltage regulator U5; the voltage regulator U5 is connected in parallel with the second voltage-dividing resistor R2.

[0066] In one embodiment, the feedback module 150 further includes a voltage dividing unit, and the voltage dividing unit includes a fifth resistor R5 and a sixth resistor R6; a first end of the fifth resistor R5 is connected to the output module 130, and a second end of the fifth resistor R5 is connected to a first end of the sixth resistor R6; the first end of the sixth resistor R6 is connected to a first input end of the comparison unit, and a second end of the sixth resistor R6 is grounded.

[0067] Specifically, as Figure 5 shown, Figure 5 FIG. is a schematic structural diagram of the feedback module 150 provided by an embodiment of the present application. The adjustable voltage unit 154 includes a voltage regulator U5, and the voltage regulator U5 is connected in parallel with a second voltage dividing resistor R2. A first end of the voltage regulator U5 is connected to a second end of a first voltage dividing resistor R1. A second end of the voltage regulator U5 is grounded, and a third end of the voltage regulator U5 is connected to the first end of the voltage regulator U5. The second voltage dividing resistor R2 is an adjustable resistor. The first voltage dividing resistor R1 is connected to a 5V power supply. After voltage division by the first voltage dividing resistor R1, a stable 2.5V voltage (low power) can be generated across the voltage regulator U5; the second input end Uin- of the comparison unit 151 can be varied from 0V to 2.5V through the adjustable resistor; the voltage dividing unit includes a fifth resistor R5 and a sixth resistor R6, and the voltage at the first input end of the comparison unit 151 , can be regarded as , where . When the voltage Uin- at the second input end of the comparison unit 151 is greater than or equal to the voltage Uin+ at the first input end of the comparison unit 151, the comparison unit 151 outputs a low level, the isolation optocoupler 153 is cut off, and the control module 140 operates normally, and the output voltage Vout slowly rises until it is stable, . When the voltage Uin- at the second input end of the comparison unit 151 is less than the voltage Uin+ at the first input end of the comparison unit 151, the output of the comparison unit 151 is NC (Not Connected, not connected), and the pin 1 of the isolation optocoupler 153 is connected to the pull-up unit 152 and conducts, and the control module 140 stops operating, and the output voltage Vout slowly drops until , achieving a stable output voltage. According to the above logic, the output voltage can be deduced. Since the adjustable resistor can be varied from 0V to 2.5V, the voltage at the second input end of the comparison unit 151 can be varied from 0V to 2.5V. Therefore, when the voltage at the second input end of the comparison unit 151 is 0V, the output voltage is the minimum value of 0V; when the voltage at the second input end of the comparison unit 151 is 2.5V, the output voltage Vout is the maximum value, that is, the output voltage .

[0068] By providing an adjustable resistor in this application, the voltage value at the second input terminal of the comparison unit 151, i.e., the range of the reference voltage, can be adjusted, enabling the output voltage of the flyback circuit to be any voltage value within (V). The flyback circuit can not only achieve an output voltage of 0 but also output voltages of different levels to adjust the accuracy of the output voltage. Among them, the voltage regulator U5 is used to control the accuracy adjustment of the output voltage.

[0069] In one embodiment, the adjustable voltage unit 154 further includes a third resistor R3; the third resistor R3 is connected in parallel with the second voltage-dividing resistor R2. As Figure 6 shown, Figure 6 is a schematic structural diagram of the feedback module 150 provided in another embodiment of this application. In some applications, if the circuit has low requirements for the accuracy of the output voltage or the input voltage and load conditions are relatively stable, a resistor can be used instead of the voltage regulator U5. Specifically, by adjusting the resistor, the reference voltage is changed, thereby controlling the output voltage of the flyback circuit. The third resistor R3 and the adjustable resistor together form a voltage divider. By adjusting the resistance value of the adjustable resistor, the voltage Uin- at the second input terminal of the comparator is changed, and thus the output voltage Vout is adjusted. By using the third resistor R3 instead of the voltage regulator U5 in this application, the circuit structure can be simplified and the cost can be reduced.

[0070] In one embodiment, as Figure 7 shown, Figure 7 is a schematic structural diagram of the isolated power supply provided in one embodiment of this application. The flyback circuit further includes an isolated power supply, which is connected to the rectification and filtering module and is used to output a first power supply.

[0071] Specifically, the isolated power supply supplies power to the comparison unit 151, the voltage regulator U5, and the isolated optocoupler 153. In one embodiment, the output voltage of the isolated power supply is 5V, which is generated by an AC-DC low-power isolated power supply and is grounded with the output voltage. The isolated power supply is a small-power power supply with low power and low cost. In some other embodiments, the output voltage of the isolated power supply can also be 12V or 15V. For the same power requirement in this embodiment, a higher voltage means a lower current, and a lower current can reduce the voltage drop and power loss on the wires and PCB traces.

[0072] In one embodiment, referring to Figure 1 , the output module 130 includes a first diode, a second capacitor, and a load R0; the anode of the first diode is connected to the first end of the secondary winding, the cathode of the first diode is connected to the first end of the second capacitor and the first end of the load R0; the second end of the second capacitor is connected to the second end of the secondary winding, and the second end of the load R0 is grounded.

[0073] This application provides a motor control circuit, including a flyback circuit as described above.

[0074] The main functions of the flyback circuit are power conversion and voltage regulation, which can provide a stable voltage for motor drive. For example, in the power supply module of a motor controller, the flyback circuit can be used to provide a stable low-voltage power supply for the motor controller; in the microcontroller, sensors and other low-power electronic components in the motor controller, the flyback circuit can convert the high-voltage power supply into a low-voltage power supply suitable for these components and provide a stable voltage for them; secondly, the flyback circuit can also be applied to the auxiliary power supply of motor drivers (servo drive, frequency converter drive, DC motor drive, stepper motor drive, brushless DC motor drive (BLDC drive), AC motor drive)); in some complex motor drivers, multiple voltage levels of power supply may be required, and the flyback circuit can be used to generate these auxiliary power supplies to support the normal operation of the driver. The flyback circuit can be used in the motor protection circuit to provide a stable power supply for the protection circuit. For example, overcurrent protection, overvoltage protection and temperature protection circuits all require a stable power supply to monitor and respond to abnormal conditions of the motor, ensuring the stable and reliable operation of the entire system.

[0075] Those skilled in the art will readily conceive of other embodiments of this application after considering the specification and practicing the technology disclosed herein. This application is intended to cover any variations, uses, or adaptations of this application, which follow the general principles of this application and include known common knowledge or conventional technical means in the technical field not disclosed in this application. The specification and examples are only regarded as exemplary, and the true scope and spirit of this application are pointed out by the following claims.

[0076] It should be understood that this application is not limited to the exact structures described above and shown in the drawings, and various modifications and changes can be made without departing from its scope. The scope of this application is only limited by the appended claims.

Claims

1. A flyback circuit, characterized in that: include: A rectifier and filter module, a transformer, an output module, a control module and a feedback module, wherein the transformer includes a primary winding and a secondary winding; The input end of the rectifier and filter module is connected to the alternating current, the output end of the rectifier and filter module is connected to the first end of the primary winding of the transformer, and the control module is connected to the second end of the primary winding; A first end of the output module is connected to the secondary winding of the transformer, a second end of the output module is connected to the feedback module, and the feedback module is connected to the control module; The feedback module includes an isolation optocoupler, a comparison unit and a pull-up unit; the first input end of the comparison unit is connected to the output module, the second input end of the comparison unit is used to access a reference voltage, the output end of the comparison unit is connected to the isolation optocoupler through the pull-up unit, and the reference voltage is greater than or equal to 0.

2. The flyback circuit according to claim 1, characterized in that: The isolation optocoupler outputs a first signal when the comparison unit detects that the output voltage of the output module is greater than the reference voltage, and the isolation optocoupler outputs a second signal when the comparison unit detects that the output voltage is less than or equal to the reference voltage; The control module is disconnected when receiving the first signal; and is connected when receiving the second signal.

3. The flyback circuit according to claim 2, characterized in that: The feedback module further includes an adjustable voltage unit, and the adjustable voltage unit is connected to the second input terminal of the comparison unit; The adjustable voltage unit is used to generate the reference voltage.

4. The flyback circuit according to claim 3, characterized in that: The adjustable voltage unit includes a first voltage-dividing resistor and a second voltage-dividing resistor; A first end of the first voltage-dividing resistor is connected to a first power supply, a second end of the first voltage-dividing resistor is connected to a first end of the second voltage-dividing resistor, and a second end of the second voltage-dividing resistor is grounded; The output end of the second voltage-dividing resistor is connected to the second input end of the comparison unit.

5. The flyback circuit according to claim 4, characterized in that: The adjustable voltage unit also includes a voltage stabilizer or a third resistor; The voltage regulator or the third resistor is connected in parallel with the second voltage-dividing resistor.

6. The flyback circuit according to claim 4 or 5, characterized in that: The second voltage-dividing resistor is an adjustable resistor.

7. The flyback circuit according to claim 2, characterized in that: The pull-up unit includes a fourth resistor, a first end of the fourth resistor is connected to the first power supply, and a second end of the fourth resistor is connected to the isolation optical coupler and the comparison unit.

8. The flyback circuit according to claim 1, characterized in that: The flyback circuit also includes an isolated power supply, which is connected to the rectification and filtering module and is used to output a first power supply.

9. The flyback circuit according to claim 2, characterized in that: The feedback module further includes a voltage dividing unit, and the voltage dividing unit includes a fifth resistor and a sixth resistor; The first end of the fifth resistor is connected to the output module, and the second end of the fifth resistor is connected to the first end of the sixth resistor; A first end of the sixth resistor is connected to the first input end of the comparison unit, and a second end of the sixth resistor is grounded.

10. A motor control circuit, characterized in that: The invention comprises a flyback circuit as described in any one of claims 1 to 9.

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