An isolated driving power supply with under-voltage protection

Abstract

The application discloses an isolated driving power supply with under-voltage protection, comprising a full-bridge driving module, an isolation transformer module, a rectification and current-filling blocking module and an output under-voltage protection module; the full-bridge driving module transmits two-way PWM signals with a dead zone to the secondary side through the isolation transformer; the rectification and current-filling blocking module utilizes a voltage doubling diode and a rectifier diode to rectify the alternating current of the secondary side into direct current output, and utilizes the one-way conduction characteristic of the diode to block the reverse current filling; the output under-voltage protection module samples the output voltage in real time through a resistance voltage dividing network, compares the output voltage with a reference voltage through a comparator, and when the output voltage is lower than the set threshold, the comparator outputs a fault signal to the enable end of the full-bridge driving chip through an isolated optocoupler, so as to quickly lock the PWM output; the application realizes the double functions of reliable output under-voltage protection and current-filling blocking, effectively avoids the problems that the later-stage power device is damaged due to insufficient driving voltage and the front-stage circuit is damaged due to the reverse filling of fault current.

Description

Technical Field

[0001] This invention relates to the field of switching power supply technology, and more specifically to an isolated drive power supply with undervoltage protection. Background Technology

[0002] Most existing low-power isolated drive power supplies adopt a discrete transistor push-pull topology with a Zener diode clamping structure, such as... Figure 1 As shown: The input is a +12V DC voltage, which is generated by a DSP chip into a single PWM signal. This signal is then driven by a Darlington driver chip (1-16, 1B-7B, 1C-7C, E, and COM are all chip pins) to drive a push-pull power transistor. Electrical isolation is achieved through a high-frequency transformer. The secondary side is rectified by a diode and then passively clamped and regulated by a Zener diode. The output includes multiple voltages such as +15V and -7V, which are used to drive and power devices such as IGBTs. N3 is the primary winding of the transformer, and N1 is the secondary winding of the transformer.

[0003] like Figure 2 As shown, with Figure 1 The solution is similar, using a PWM chip (pins 1-8, COMP, VREF, GND, VDD, OUT, CS, FB, and RT / CT are all chip pins) to output a PWM waveform to drive a push-pull power transistor to achieve isolated power output. B / E / C are the base, emitter, and collector of the transistor, respectively. DR.COMP is the chip's stop signal, controlled by a signal from the DSP. Normally, this signal is high; it is low when the chip stops working.

[0004] Problems with existing technology: 1. Push-pull structures are prone to core magnetization and power device shoot-through. Furthermore, the power transistors need to withstand twice the input voltage stress, and output overload or short circuit can damage components, resulting in high selection costs and failure risks.

[0005] 2. The power circuit is directly coupled to the Zener diode. When the load power device is short-circuited, the fault sink current will directly impact the Zener diode, causing it to burn out due to overpower, which in turn leads to uncontrolled output voltage.

[0006] To address the above problems, this invention proposes an isolated drive power supply with undervoltage protection. Summary of the Invention

[0007] The purpose of this invention is to address the limitations of existing technologies by adopting the following technical solution: An isolated drive power supply device with undervoltage protection is characterized in that the device includes a full-bridge drive module, an isolation transformer module, a rectification and current sinking blocking module, and an output undervoltage protection module; wherein, the full-bridge drive module includes a drive chip U1 and peripheral resistors and capacitors, the peripheral resistors and capacitors being connected to the power supply terminal, enable terminal, and clock signal terminal of the drive chip U1; the isolation transformer module includes a primary winding and a secondary winding, the output terminal of the drive chip U1 being connected to the primary winding, the secondary winding being connected to the rectification and current sinking blocking module, and the output undervoltage protection module being connected between the full-bridge drive module and the rectification and current sinking blocking module.

[0008] Furthermore, the peripheral configuration resistors and capacitors include a first resistor R1, a third resistor R3, a fifth resistor R5, a fourth capacitor C4, and a fifth capacitor C5. One end of the first resistor R1 is connected to the clock signal terminal of the driver chip U1, and the other end is grounded. One end of the third resistor R3 is connected to the power supply, and the other end is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the enable terminal of the driver chip U1. One end of the fourth capacitor C4 is connected to the first power supply, and the other end is grounded. One end of the fifth capacitor C5 is connected to the enable terminal of the driver chip U1, and the other end is grounded.

[0009] Furthermore, in the rectification and current-sinking blocking module, the filter capacitors include a first filter capacitor C2 and a second filter capacitor C3. One end of the voltage multiplier capacitor C1 is connected to the same-name terminal of the secondary winding of the isolation transformer, and the other end is connected to the negative terminal of the voltage multiplier diode D2. The negative terminal of the voltage multiplier diode D2 is also connected to the positive terminal of the first full-wave rectifier diode D1. The positive terminal of the voltage multiplier diode D2 is connected to one end of the first filter capacitor C2 and the opposite-name terminal of the secondary winding of the isolation transformer. The other end of the first filter capacitor C2 is connected to the negative terminal of the first full-wave rectifier diode D1. One end of the second filter capacitor C3 is connected to the positive terminal of the voltage multiplier diode D2, and the other end is connected to the positive terminal of the second full-wave rectifier diode D3. The negative terminal of the second full-wave rectifier diode D3 is connected to the same-name terminal of the secondary winding of the isolation transformer.

[0010] Furthermore, one end of the first filter capacitor is grounded, and the other end outputs a +15V DC voltage; one end of the second filter capacitor is grounded, and the other end outputs a -7V DC voltage.

[0011] Furthermore, the output undervoltage protection module includes an isolation optocoupler U3, several resistors, several transistors, several capacitors, several diodes, a Zener diode U4, and a comparator; the several resistors include the fourth resistor R4, the second resistor R2, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the eleventh resistor R11, the tenth resistor R10, the thirteenth resistor R13, the fifteenth resistor R15, the twelfth resistor R12, the sixteenth resistor R16, the fourteenth resistor R14, the seventeenth resistor R17, and the eighteenth resistor R18; the several transistors include the first transistor Q1 and the second transistor Q2; the several capacitors include the sixth capacitor C6, the ninth capacitor C9, the seventh capacitor C7, and so on. The eighth capacitor C8, the tenth capacitor C10, and the eleventh capacitor C11; the plurality of diodes include the fifth diode D5, the fourth diode D4, and the sixth diode D6; the output collector of the isolation optocoupler U3 is connected to the enable terminal of the driver chip U1, and the collector is grounded; the positive terminal of the input side of the isolation optocoupler U3 is connected to the collector of the first transistor, and the negative terminal is grounded; the emitter of the first transistor Q1 is connected to one end of the seventh resistor R7, and the base is connected to the negative terminal of the sixth diode D6; the positive terminal of the sixth diode D6 is grounded; the other end of the seventh resistor R7 is connected to the second power supply; one end of the eighth resistor R8 is connected to the second power supply, and the other end is connected to the negative terminal of the sixth diode D6; one end of the ninth resistor is connected to the third power supply, and the other end is connected to the negative terminal of the sixth diode D6; the negative terminal of the fifth diode is connected to the third power supply. The positive terminal is connected to the negative terminal of the sixth diode D6; the negative terminal of the fourth diode is connected to the negative terminal of the sixth diode D6, and the positive terminal is connected to one end of the sixth resistor R6; the other end of the sixth resistor R6 is connected to one end of the seventh capacitor C7; the eleventh resistor is connected between the negative terminal of the sixth diode D6 and the comparator output; the positive power supply terminal of the comparator is connected to the fourth power supply and one end of the sixth capacitor C6; the other end of the sixth capacitor C6 is grounded; the negative power supply terminal of the comparator is connected to the fifth power supply and one end of the ninth capacitor C9; the other end of the ninth capacitor C9 is grounded; the inverting terminal of the comparator is connected to one end of the thirteenth resistor R13, one end of the eighth capacitor C8, the collector of the second transistor Q2, and one end of the twelfth resistor R12; the other ends of the thirteenth resistor R13, the seventh capacitor C7, and the eighth capacitor C8 are all connected to... Ground; the emitter of the second transistor Q2 is grounded, and its base is connected to one end of the tenth capacitor, one end of the fifteenth resistor, and one end of the sixteenth resistor, respectively; the other end of the tenth capacitor and the other end of the sixteenth resistor are both grounded; the other end of the fifteenth resistor is connected to the undervoltage protection signal output by the DSP; one end of the tenth resistor R10 is connected to the non-inverting input of the comparator, and the other end is connected to one end of the second resistor R2; the other end of the twelfth resistor R12 is connected to one end of the eleventh capacitor C11, one end of the seventeenth resistor R17, and one end of the fourteenth resistor R14, respectively; the other end of the eleventh capacitor C11 is grounded; the other end of the seventeenth resistor R17 is connected to one end of the eighteenth resistor R18 and the common terminal of the Zener diode U4, respectively; one end of the fourteenth resistor R14 is connected to the negative terminal of the Zener diode U4, and the other end is connected to the fourth power supply;The other end of the eighteenth resistor R18 is grounded; the positive terminal of the Zener diode U4 is grounded; one end of the fourth resistor R4 is connected to the negative terminal of the first full-wave rectifier diode D1, and the other end is connected to one end of the second resistor R2, the other end of which is grounded.

[0012] Furthermore, the first, third, and fourth power supplies are all +12V DC; the second power supply is +3.3V DC; and the fifth power supply is -12V DC.

[0013] This invention incorporates an output voltage detection and undervoltage protection circuit at the output terminal. It samples the output voltage in real time using a resistor divider network and compares it with a reference voltage. When the output voltage falls below a set threshold, the comparator outputs a fault signal to quickly block the PWM output of the driver chip and shut down the full-bridge power transistor drive signal. This prevents the downstream IGBTs or MOSFETs from overheating and being damaged due to insufficient drive voltage operating in the linear region, effectively improving the safety and reliability of the power supply under startup and sudden load changes. Simultaneously, the rectifier module of this invention uses a transformer with a single-winding rectifier diode to form an independent full-wave rectification structure. The positive and negative output circuits are rectified separately, achieving positive and negative voltage outputs without relying on a Zener diode. This avoids the inherent defect of Zener diodes being prone to overcurrent burnout during output short circuits and eliminates the safety hazard of Zener diodes as potential failure points. Furthermore, the undervoltage protection has a self-locking function, requiring power-on or external reset to restore output. This, in conjunction with the rectifier module, ensures that the power transistors are not re-driven during a fault, further enhancing the long-term operational stability of the system under abnormal conditions.

[0014] To further understand the features and technical content of the present invention, please refer to the following detailed description and drawings of the present invention. However, the drawings provided are for reference and illustration only and are not intended to limit the present invention. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the existing technology that uses a Darlington transistor to drive a push-pull power transistor and a Zener diode for clamping. Figure 2 This is a schematic diagram of the existing technology that uses a PWM chip to drive a push-pull power transistor and clamp it with an output Zener diode; Figure 3 This is a schematic diagram of the isolated drive power supply of the present invention. Detailed Implementation

[0016] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can understand the advantages and effects of the present invention from the content disclosed in this specification. The present invention can be implemented or applied through other different specific embodiments, and various details in this specification can also be modified and changed based on different viewpoints and applications without departing from the spirit of the present invention. Furthermore, the accompanying drawings of the present invention are for simple illustrative purposes only and are not depictions of actual dimensions; this is stated in advance. The following embodiments will further describe the relevant technical content of the present invention in detail, but the disclosed content is not intended to limit the scope of protection of the present invention.

[0017] Example 1: As Figure 3 As shown, the device includes a full-bridge drive module, an isolation transformer module, a rectification and current sinking blocking module, and an output undervoltage protection module. The full-bridge drive module includes a driver chip U1 and peripheral resistors and capacitors, which are connected to the power supply terminal, enable terminal, and clock signal terminal of the driver chip U1. The isolation transformer module includes a primary winding and a secondary winding. The output terminal of the driver chip U1 is connected to the primary winding, and the secondary winding is connected to the rectification and current sinking blocking module. The output undervoltage protection module is connected between the full-bridge drive module and the rectification and current sinking blocking module.

[0018] The full-bridge driver module converts the first power input into a high-frequency AC square wave; the first power supply is preferably +12V DC; the isolation transformer module is used to achieve electrical isolation and voltage transformation between the primary and secondary sides, providing isolated AC input for the subsequent output; the rectification and current sinking blocking module includes a voltage multiplier diode D1, a rectifier diode D2, and filter capacitors C2 and C3. This rectification and current sinking blocking module utilizes the unidirectional conduction characteristic of the rectifier diode to block reverse current sinking, while rectifying the high-frequency AC on the secondary side into DC output, achieving positive and negative voltage output without the need for a Zener diode; the output undervoltage protection module includes a resistor divider network, a comparator U3, and a reference voltage. Upon power-on initialization, this output undervoltage protection module samples the output voltage in real time and compares it with the reference voltage. When the output voltage is lower than a set threshold, a fault signal is output, which blocks the PWM output of the driver chip U1 via the enable control terminal.

[0019] Furthermore, the peripheral configuration resistors and capacitors include a first resistor R1, a third resistor R3, a fifth resistor R5, a fourth capacitor C4, and a fifth capacitor C5. One end of the first resistor R1 is connected to the clock signal terminal of the driver chip U1, and the other end is grounded; one end of the third resistor R3 is connected to the power supply, and the other end is connected to one end of the fifth resistor R5; the other end of the fifth resistor R5 is connected to the enable terminal of the driver chip U1; one end of the fourth capacitor C4 is connected to the first power supply, and the other end is grounded; one end of the fifth capacitor C5 is connected to the enable terminal of the driver chip U1, and the other end is grounded.

[0020] like Figure 3As shown, the full-bridge drive module includes a full-bridge drive chip, an enable current-limiting resistor, a filter capacitor, and an oscillator adjustment resistor; the enable current-limiting resistor includes two resistors, and the filter capacitor includes a +12V filter capacitor and an enable pin filter capacitor.

[0021] Isolation transformer module: includes primary winding (N3) and secondary winding (N1), realizes electrical isolation and voltage transformation between primary and secondary sides, and provides isolated AC input for subsequent output.

[0022] Furthermore, in the rectification and current-sinking blocking module, the filter capacitors include a first filter capacitor C2 and a second filter capacitor C3. One end of the voltage multiplier capacitor C1 is connected to the same-name terminal of the secondary winding of the isolation transformer, and the other end is connected to the negative terminal of the voltage multiplier diode D2. The negative terminal of the voltage multiplier diode D2 is also connected to the positive terminal of the first full-wave rectifier diode D1. The positive terminal of the voltage multiplier diode D2 is connected to one end of the first filter capacitor C2 and the opposite-name terminal of the secondary winding of the isolation transformer. The other end of the first filter capacitor C2 is connected to the negative terminal of the first full-wave rectifier diode D1. One end of the second filter capacitor C3 is connected to the positive terminal of the voltage multiplier diode D2, and the other end is connected to the positive terminal of the second full-wave rectifier diode D3. The negative terminal of the second full-wave rectifier diode D3 is connected to the same-name terminal of the secondary winding of the isolation transformer. The rectification and current-sinking blocking module utilizes the unidirectional conduction characteristic of diodes to block reverse current sinking, while simultaneously rectifying the high-frequency AC on the secondary side into DC output, preventing fault current backflow from damaging the Zener diode and the downstream load.

[0023] Furthermore, one end of the first filter capacitor C2 is grounded, and the other end outputs a +15V DC voltage; one end of the second filter capacitor C3 is grounded, and the other end outputs a -7V DC voltage.

[0024] Furthermore, the output undervoltage protection module includes an isolation optocoupler U3, several resistors, several transistors, several capacitors, several diodes, a Zener diode U4, and a comparator; the several resistors include the fourth resistor R4, the second resistor R2, the sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the eleventh resistor R11, the tenth resistor R10, the thirteenth resistor R13, the fifteenth resistor R15, the twelfth resistor R12, the sixteenth resistor R16, the fourteenth resistor R14, the seventeenth resistor R17, and the eighteenth resistor R18; the several transistors include the first transistor Q1 and the second transistor Q2; the several capacitors include the sixth capacitor C6, the ninth capacitor C9, the seventh capacitor C7, and so on. The eighth capacitor C8, the tenth capacitor C10, and the eleventh capacitor C11; the plurality of diodes include the fifth diode D5, the fourth diode D4, and the sixth diode D6; the output collector of the isolation optocoupler U3 is connected to the enable terminal of the driver chip U1, and the collector is grounded; the positive terminal of the input side of the isolation optocoupler U3 is connected to the collector of the first transistor, and the negative terminal is grounded; the emitter of the first transistor Q1 is connected to one end of the seventh resistor R7, and the base is connected to the negative terminal of the sixth diode D6; the positive terminal of the sixth diode D6 is grounded; the other end of the seventh resistor R7 is connected to the second power supply; one end of the eighth resistor R8 is connected to the second power supply, and the other end is connected to the negative terminal of the sixth diode D6; one end of the ninth resistor is connected to the third power supply, and the other end is connected to the negative terminal of the sixth diode D6; the negative terminal of the fifth diode is connected to the third power supply. The positive terminal is connected to the negative terminal of the sixth diode D6; the negative terminal of the fourth diode is connected to the negative terminal of the sixth diode D6, and the positive terminal is connected to one end of the sixth resistor R6; the other end of the sixth resistor R6 is connected to one end of the seventh capacitor C7; the eleventh resistor is connected between the negative terminal of the sixth diode D6 and the comparator output; the positive power supply terminal of the comparator is connected to the fourth power supply and one end of the sixth capacitor C6; the other end of the sixth capacitor C6 is grounded; the negative power supply terminal of the comparator is connected to the fifth power supply and one end of the ninth capacitor C9; the other end of the ninth capacitor C9 is grounded; the inverting terminal of the comparator is connected to one end of the thirteenth resistor R13, one end of the eighth capacitor C8, the collector of the second transistor Q2, and one end of the twelfth resistor R12; the other ends of the thirteenth resistor R13, the seventh capacitor C7, and the eighth capacitor C8 are all connected to... Ground; the emitter of the second transistor Q2 is grounded, and its base is connected to one end of the tenth capacitor, one end of the fifteenth resistor, and one end of the sixteenth resistor, respectively; the other end of the tenth capacitor and the other end of the sixteenth resistor are both grounded; the other end of the fifteenth resistor is connected to the undervoltage protection signal output by the DSP; one end of the tenth resistor R10 is connected to the non-inverting input of the comparator, and the other end is connected to one end of the second resistor R2; the other end of the twelfth resistor R12 is connected to one end of the eleventh capacitor C11, one end of the seventeenth resistor R17, and one end of the fourteenth resistor R14, respectively; the other end of the eleventh capacitor C11 is grounded; the other end of the seventeenth resistor R17 is connected to one end of the eighteenth resistor R18 and the common terminal of the Zener diode U4, respectively; one end of the fourteenth resistor R14 is connected to the negative terminal of the Zener diode U4, and the other end is connected to the fourth power supply;The other end of the eighteenth resistor R18 is grounded; the positive terminal of the Zener diode U4 is grounded; one end of the fourth resistor R4 is connected to the negative terminal of the first full-wave rectifier diode D1, and the other end is connected to one end of the second resistor R2, the other end of which is grounded.

[0025] Furthermore, the second resistor R2 and the fourth resistor R4 are both voltage sampling resistors.

[0026] Furthermore, the first, third, and fourth power supplies are all +12V DC; the second power supply is +3.3V DC; and the fifth power supply is -12V DC.

[0027] The reference voltage includes R14, U4, R17, R18, and C11; the power-on initialization circuit includes: the UVP_RESET signal from the DSP, current-limiting resistor R15, voltage divider resistor R16, filter capacitor C10, and NPN transistor Q2; the comparator circuit includes: input current-limiting resistors R10 and R12, input filter capacitors C7 and C8, output current-limiting resistor R11, output pull-up resistors R8 and R9, and clamping diodes D5 and D6; the self-locking circuit includes resistor R6 and diode D4; and the enable control circuit includes: current-limiting resistor R7, PNP transistor Q1, and isolation optocoupler U3. Upon initial power-up, the DSP sends a UVP_RESET high-level signal, maintaining it until the 15V and -7V outputs are normal, then stops outputting. The +12V2 voltage is divided by resistors R17 and R18 and the three-terminal regulator U4 outputs a reference voltage, which is compared with the sampled voltage divided by R2 and R4. When the sampled voltage is lower than the reference voltage, the comparator output is pulled low, triggering the latching circuit. The non-inverting input voltage of the comparator is pulled low, requiring a power-off to restore it. After the comparator output is pulled low, PNP transistor Q1 conducts, the primary-side LED of optocoupler U3 conducts, and the secondary-side transistor of optocoupler conducts. The enable pin of the full-bridge driver chip U1 is pulled low, and the chip does not work.

[0028] Beneficial effects of the embodiments: Output undervoltage reliable protection: The resistor divider network samples the output voltage in real time and compares it with the reference voltage through a comparator. When the output voltage is lower than the set threshold, the PWM output of the driver chip is quickly blocked to prevent the downstream IGBT or MOSFET from overheating and being damaged due to insufficient drive voltage and operating in the linear region. The undervoltage threshold can be flexibly adjusted through the voltage divider resistor to adapt to the drive voltage requirements of different power devices.

[0029] Enhanced current sinking protection: The electrical isolation of transformer T1 and the unidirectional conduction characteristic of secondary rectifier diode D1 form a dual blocking path. When the downstream power transistor is short-circuited or the drive is overloaded, the fault current is limited to the secondary circuit and cannot be reversed to the primary drive chip U1 and the front-end power supply network, effectively avoiding damage to the front-end control circuit due to current reverse sinking. At the same time, positive and negative voltage output can be achieved without Zener diodes, which avoids the inherent defect of Zener diodes being easily burned out by overcurrent when the output is short-circuited, and also eliminates the safety hazard of Zener diodes as potential failure points, significantly improving the system reliability of the drive power supply under abnormal operating conditions.

[0030] The content disclosed above is only a preferred and feasible embodiment of the present invention, and is not intended to limit the scope of protection of the present invention. Therefore, all equivalent technical changes made based on the content of the present invention specification and drawings are included within the scope of protection of the present invention. Furthermore, the elements therein can be updated as technology develops.

Claims

1. An isolated drive power supply device with undervoltage protection, characterized in that, The device includes a full-bridge drive module, an isolation transformer module, a rectification and current sinking blocking module, and an output undervoltage protection module. The full-bridge drive module includes a driver chip U1 and peripheral resistors and capacitors, which are connected to the power supply, enable, and clock signal terminals of the driver chip U1. The isolation transformer module includes a primary winding and a secondary winding. The output terminal of the driver chip U1 is connected to the primary winding, and the secondary winding is connected to the rectification and current sinking blocking module. The output undervoltage protection module is connected between the full-bridge drive module and the rectification and current sinking blocking module.

2. The isolated drive power supply device with undervoltage protection as described in claim 1, characterized in that, The peripheral configuration resistors and capacitors include a first resistor R1, a third resistor R3, a fifth resistor R5, a fourth capacitor C4, and a fifth capacitor C5. One end of the first resistor R1 is connected to the clock signal terminal of the driver chip U1, and the other end is grounded. One end of the third resistor R3 is connected to the power supply, and the other end is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 is connected to the enable terminal of the driver chip U1; one end of the fourth capacitor C4 is connected to the first power supply and the other end is grounded; one end of the fifth capacitor C5 is connected to the enable terminal of the driver chip U1 and the other end is grounded.

3. The isolated drive power supply device with undervoltage protection as described in claim 2, characterized in that, In the rectification and current sinking blocking module, the filter capacitors include a first filter capacitor C2 and a second filter capacitor C3. One end of the voltage multiplier capacitor C1 is connected to the same-name terminal of the secondary winding of the isolation transformer, and the other end is connected to the negative terminal of the voltage multiplier diode D2. The negative terminal of the voltage multiplier diode D2 is also connected to the positive terminal of the first full-wave rectifier diode D1. The positive terminal of the voltage multiplier diode D2 is connected to one end of the first filter capacitor C2 and the opposite-name terminal of the secondary winding of the isolation transformer. The other end of the first filter capacitor C2 is connected to the negative terminal of the first full-wave rectifier diode D1. One end of the second filter capacitor C3 is connected to the positive terminal of the voltage multiplier diode D2, and the other end is connected to the positive terminal of the second full-wave rectifier diode D3. The negative terminal of the second full-wave rectifier diode D3 is connected to the same-name terminal of the secondary winding of the isolation transformer.

4. The isolated drive power supply device with undervoltage protection as described in claim 3, characterized in that, One end of the first filter capacitor is grounded, and the other end outputs a +15V DC voltage. One end of the second filter capacitor is grounded, and the other end outputs a -7V DC voltage.

5. The isolated drive power supply device with undervoltage protection as described in claim 4, characterized in that, The output undervoltage protection module includes an isolation optocoupler U3, several resistors, several transistors, several capacitors, several diodes, a Zener diode U4, and a comparator. The resistors include resistors R4, R2, R6, R7, R8, R9, R11, R10, R13, R15, R12, R16, R14, R17, and R18. The transistors include transistor Q1 and transistor Q2. The capacitors include capacitors C6, C9, C7, and C8. The tenth capacitor C10 and the eleventh capacitor C11; the plurality of diodes include the fifth diode D5, the fourth diode D4, and the sixth diode D6; the collector of the output side of the isolation optocoupler U3 is connected to the enable terminal of the driver chip U1, and the collector is grounded; the positive terminal of the input side of the isolation optocoupler U3 is connected to the collector of the first transistor, and the negative terminal is grounded; the emitter of the first transistor Q1 is connected to one end of the seventh resistor R7, and the base is connected to the negative terminal of the sixth diode D6; the positive terminal of the sixth diode D6 is grounded; the other end of the seventh resistor R7 is connected to the second power supply; one end of the eighth resistor R8 is connected to the second power supply, and the other end is connected to the negative terminal of the sixth diode D6; one end of the ninth resistor is connected to the third power supply, and the other end is connected to the negative terminal of the sixth diode D6; the negative terminal of the fifth diode is connected to the third power supply, and the positive terminal is connected to the sixth diode D6. The negative terminal of diode D6 is connected to the negative terminal of diode D6, and the positive terminal is connected to one end of resistor R6. The other end of resistor R6 is connected to one end of capacitor C7. Resistor 11 is connected between the negative terminal of diode D6 and the output of comparator. The positive power supply of comparator is connected to the fourth power supply and one end of capacitor C6. The other end of capacitor C6 is grounded. The negative power supply of comparator is connected to the fifth power supply and one end of capacitor C9. The other end of capacitor C9 is grounded. The inverting terminal of comparator is connected to one end of resistor R13, one end of capacitor C8, the collector of transistor Q2, and one end of resistor R12. The other ends of resistor R13, capacitor C7, and capacitor C8 are all grounded. Transistor Q2 emits... The base of resistor R10 is connected to one end of the tenth capacitor, one end of the fifteenth resistor, and one end of the sixteenth resistor, respectively. The other ends of the tenth capacitor and the sixteenth resistor are both grounded. The other end of the fifteenth resistor is connected to the undervoltage protection signal output by the DSP. One end of the tenth resistor R10 is connected to the non-inverting input of the comparator, and the other end is connected to one end of the second resistor R2. The other end of the twelfth resistor R12 is connected to one end of the eleventh capacitor C11, one end of the seventeenth resistor R17, and one end of the fourteenth resistor R14, respectively. The other end of the eleventh capacitor C11 is grounded. The other end of the seventeenth resistor R17 is connected to one end of the eighteenth resistor R18 and the common terminal of the Zener diode U4, respectively. One end of the fourteenth resistor R14 is connected to the negative terminal of the Zener diode U4, and the other end is connected to the fourth power supply. The other end of the eighteenth resistor R18 is grounded.The positive terminal of Zener diode U4 is grounded; one end of the fourth resistor R4 is connected to the negative terminal of the first full-wave rectifier diode D1, and the other end is connected to one end of the second resistor R2, the other end of which is grounded.

6. The isolated drive power supply device with undervoltage protection as described in claim 5, characterized in that, The first, third, and fourth power supplies are all +12V DC; the second power supply is +3.3V DC; and the fifth power supply is -12V DC.

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