Inverter control constant voltage power supply device

Abstract

The application relates to the technical field of circuits, and discloses an inverter control constant-voltage power supply device which comprises a power board, a control board, a power supply board and a display board; the power board comprises a pre-charging module, a voltage stabilizing module and a driving control module; the voltage stabilizing module comprises a voltage stabilizing circuit; the application adopts a topological structure of a totem pole bridgeless PFC input + full-bridge inverter output, directly realizes the voltage stabilizing function through power electronic technology, does not need the power frequency compensation transformer and the voltage regulating transformer which are indispensable for traditional compensation type voltage stabilizers, greatly reduces the volume and weight of the equipment, and reduces the manufacturing cost.

Description

Technical Field

[0001] This invention relates to the field of circuit technology, and more specifically, to an inverter-controlled constant voltage power supply device. Background Technology

[0002] With the advancement of science and technology, modern precision equipment and instruments have increasingly higher requirements for power quality. Improving power quality has become a crucial issue, and voltage stability is a key indicator of power quality. Therefore, voltage regulators are receiving increasing attention. Currently, widely used voltage regulators are mainly divided into two categories: contact-type voltage regulators and contactless voltage regulators. Contact-type voltage regulators further include direct voltage regulators and compensated voltage regulators.

[0003] Contact-type voltage regulators have significant drawbacks: low voltage regulation accuracy, slow voltage adjustment speed, mechanical wear between the carbon brushes and transformer coils requiring regular maintenance, and short lifespan. Furthermore, the sliding of the carbon brushes on the transformer coils can easily lead to mechanical failures and sparks at the contact points, potentially causing burnout and accidents. Additionally, due to the characteristics of autotransformers, the capacity of direct-type voltage regulators is usually limited. While compensated-type voltage regulators increase capacity to some extent compared to direct-type regulators, they also share the disadvantages of direct-type regulators. They also require a bulky power frequency compensation transformer. Contactless compensated-type voltage regulators also require a bulky power frequency transformer, resulting in complex circuitry, numerous components, and high cost. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention provides an inverter-controlled constant voltage power supply device.

[0005] An inverter-controlled constant voltage power supply device includes: a power board, a control board, a power supply board, and a display board;

[0006] The power board includes: a precharge module, a voltage regulator module, and a drive control module;

[0007] The voltage regulator module includes a voltage regulator circuit, which includes:

[0008] The input-side energy storage filter capacitor C1 is used to filter the input voltage.

[0009] PFC boost inductor L1 is used for power factor correction and voltage boosting;

[0010] Bus filter capacitor C3 is used to store and stabilize the DC bus voltage;

[0011] The inverter output filter inductor L2 and filter capacitor C2 are used to filter the pulse waveform of the inverter output into a smooth sine wave;

[0012] The six power switching transistors Q1 to Q6 and their corresponding body diodes D1 to D6 form three bridge arms:

[0013] Q1 and Q2 form the PFC high-frequency bridge arm;

[0014] Q3 and Q4 form the power frequency bridge arm, which serves as a shared bridge arm for PFC and inverter.

[0015] Q5 and Q6 form the inverter high-frequency bridge arm;

[0016] The control circuit is used to control the on / off state of each power switching transistor.

[0017] Preferably, the control board has a main control chip and peripheral circuits, a signal sampling and detection circuit, and a communication circuit.

[0018] Preferably, the power board has a bus high voltage 400V to low voltage 12V power module.

[0019] Preferably, the control circuit controls the voltage of the PFC boost inductor L1 by adjusting the duty cycle of the PFC high-frequency bridge arm switch, thereby adjusting the voltage of the bus filter capacitor C3 to keep the voltage of C3 stable.

[0020] Preferably, the control circuit controls the output voltage by adjusting the duty cycle of the inverter high-frequency bridge arm switching transistor, thereby stabilizing the output voltage.

[0021] Preferably, the voltage of the bus filter capacitor C3 is equal to the sum of the input voltage Ui and the voltage across the inductor when the PFC boost inductor L1 releases energy.

[0022] Preferably, the power switching transistors Q-Q6 are IGBTs, MOSFETs, or other power semiconductor devices.

[0023] Preferably, the body diodes D1-D6 are internal body diodes of the power switching transistor or external diodes connected in parallel.

[0024] Preferably, in each half-sine wave cycle of the high-frequency bridge arm, the two switching transistors of the high-frequency bridge arm operate in a complementary high-frequency switching mode.

[0025] Preferably, the control circuit uses SPWM modulation to control the on and off of each power switch.

[0026] The beneficial effects of this invention are as follows: This invention adopts a totem pole bridgeless PFC input + full-bridge inverter output topology, and directly realizes the voltage regulation function through power electronics technology. It eliminates the need for the power frequency compensation transformer and voltage regulating transformer that are indispensable in traditional compensated voltage regulators, which greatly reduces the size and weight of the equipment and lowers the manufacturing cost.

[0027] It adopts a high-frequency switching control method, with both the PFC operating frequency and the inverter carrier frequency at 30kHz. Compared with the mechanical sliding arm adjustment method of traditional contact voltage regulators, the response speed is increased by tens of times, the output voltage accuracy reaches 220VAC±2%, and the voltage regulation performance is excellent.

[0028] The drive circuit adopts a bootstrap scheme, requiring only three drive chips for the three bridge arms, and sharing the same 12V power supply, which greatly simplifies the circuit design and reduces the number of components and cost; it adopts a high-performance main control chip STM32G474RBT6, whose high-resolution timer HRTIM can handle complex PWM control, improving system reliability.

[0029] Multiple protection measures are implemented: an NTC thermistor at the input terminal limits the power-on surge current; fuses and varistors prevent power grid surges; dual overcurrent detection on the input and output sides; and global interruption protection for overcurrent faults, providing comprehensive protection for equipment safety; there are no mechanical contact parts, no wear, and a long service life.

[0030] The hardware system adopts a modular design, consisting of four independent modules: power board, control board, power supply board, and display board. Each module has a clear function and is independent of the others, which facilitates production assembly, later maintenance, and function upgrades. An RS232 communication interface is reserved to support firmware upgrades and remote monitoring.

[0031] The bridgeless PFC topology is adopted to correct the power factor of the input current, improve the power factor, reduce harmonic interference to the power grid, and meet the requirements of green environmental protection.

[0032] While eliminating the bulky power frequency transformer, it achieves a combination of advantages such as fast response, high-precision voltage regulation, high reliability and low cost, making it particularly suitable for low-power single-phase AC voltage regulation applications. Attached Figure Description

[0033] Figure 1 This is a hardware system block diagram of the inverter-controlled constant voltage power supply device of the present invention;

[0034] Figure 2 This is a voltage regulator circuit diagram from Embodiment 1 of the present invention;

[0035] Figure 3 This is a power schematic diagram of the voltage regulator of the present invention;

[0036] Figure 4 This is the IGBT drive circuit diagram of the present invention;

[0037] Figure 5 This is a circuit diagram of the bus pre-charging control circuit of the present invention;

[0038] Figure 6 This is a voltage acquisition circuit diagram of the present invention;

[0039] Figure 7 This invention relates to a current acquisition and overcurrent detection circuit;

[0040] Figure 8 This is a diagram showing the pin signal connection of the main control chip in this invention;

[0041] Figure 9 This is a circuit diagram of the RS232 communication module of the present invention;

[0042] Figure 10 This is the power supply circuit diagram of the control board of the present invention;

[0043] Figure 11 This is a circuit diagram of the power supply module of the power board of the present invention;

[0044] Figure 12 This is the circuit diagram of the indicator light of the present invention. Detailed Implementation

[0045] The subject matter described herein will now be discussed with reference to exemplary embodiments. It should be understood that these embodiments are discussed only to enable those skilled in the art to better understand and implement the subject matter described herein, and changes may be made to the function and arrangement of the elements discussed without departing from the scope of this specification. Various processes or components may be omitted, substituted, or added as needed in the examples. Furthermore, some features described in the examples may be combined in other examples.

[0046] Example 1

[0047] refer to Figure 2 In this embodiment, a voltage regulator circuit is proposed:

[0048] Ui is the power input voltage, Uo is the output voltage, C1 is the input-side energy storage filter capacitor, L1 is the PFC boost inductor, L2 and C2 are the inverter output filter inductor and filter capacitor, C3 is the bus filter capacitor, and Q1 to Q6 form three bridge arms. Q1 and Q2 are the high-frequency bridge arms for PFC, Q5 and Q6 are the high-frequency bridge arms for inverter, and Q3 and Q4 are the power frequency bridge arms, which are shared by PFC and inverter. D1 to D6 are the body diodes of Q1 to Q6, respectively. The voltage regulation principle will be explained in detail below. For convenience, all components are considered ideal devices:

[0049] When the input voltage is in the positive half-cycle, the lower transistor Q4 of the power frequency bridge arm is closed, and the lower transistor Q2 of the PFC high-frequency bridge arm performs high-frequency switching. When Q2 is closed, the current path is: from the input LIN, through L1-Q2-Q4, back to the input N. At this time, Ui is entirely applied to L1, and the current in L1 increases linearly, storing energy. When Q2 is open, since the current in L1 cannot change abruptly, it will freewheel through D1. The current path is: from the input LIN, through L1-D1-C3-Q4, back to the input N. At this time, the polarity of the voltage across inductor L1 reverses, L1 releases energy, and the current in L1 decreases linearly, charging C3. The voltage of C3 is equal to the sum of the input voltage Ui and the voltage across inductor L1. Meanwhile, during the period when Q4 is closed, the upper transistor Q5 of the inverter high-frequency bridge arm also performs high-frequency switching. When Q5 is closed, the current path is: from the positive terminal of C3 through Q5-L2-load-Q4 back to the negative terminal of C3. When Q5 is open, since the current on L2 cannot change abruptly, it will freewheel through D6. At this time, the current path is: from L2 through the load-Q4-D6 back to inductor L2, forming a loop. At this time, the polarity of the voltage across inductor L2 is reversed, and inductor L2 releases energy. L2 and C2 together provide energy to the load.

[0050] When the input voltage is in the negative half-cycle, the upper transistor Q3 of the power frequency bridge arm is closed, and the upper transistor Q1 of the PFC high-frequency bridge arm performs high-frequency switching. When Q1 is closed, the current path is: from input N, through Q3-Q1-L1, back to input LIN. At this time, Ui is fully applied to L1, and the current in L1 increases linearly, storing energy. When Q1 is open, the current in L1 will freewheel through D2. The current path is: from input N, through Q3-C3-D2-L1, back to input LIN. At this time, the polarity of the voltage across inductor L1 reverses, L1 releases energy, and the current in L1 decreases linearly, charging C3. The voltage of C3 is equal to the sum of the input voltage Ui and the voltage across inductor L1. Similarly, during the period when Q3 is closed, the lower transistor Q6 of the inverter high-frequency bridge arm also performs high-frequency switching. When Q6 is closed, the current path is: from the positive terminal of C3 through Q3-load-L2-Q6 back to the negative terminal of C3; when Q6 is open, the current on L2 freewheels through D5. At this time, the current path is: from L2 through D5-Q3-load back to inductor L2, forming a loop. At this time, the polarity of the voltage across inductor L2 is reversed, inductor L2 releases energy, and L2 and C2 together provide energy to the load.

[0051] During the energy release period of the PFC inductor L1, the voltage across C3 equals the sum of the input voltage Ui and the voltage across inductor L1. Therefore, by changing the duty cycle of the switching transistor in the high-frequency bridge arm, the voltage across L1 is adjusted, thereby changing the voltage across C3. This keeps C3 at a stable voltage value. On the inverter side, the output voltage is also adjusted by changing the duty cycle of the switching transistor in the inverter's high-frequency bridge arm. In the above explanation, only one transistor in the high-frequency bridge arm performs high-frequency switching in each half-sine wave cycle. The other transistor, which is in the off state, can also perform complementary high-frequency switching, which can reduce power consumption in some cases.

[0052] Example 2

[0053] Based on Example 1, this example proposes a 550VA low-power single-phase AC voltage regulator with an input voltage range of 90-310VAC and an output voltage of 220VAC±2%. The PFC operating frequency and inverter carrier frequency are both 30kHz. The hardware system block diagram is as follows. Figure 1 As shown.

[0054] The voltage regulator hardware consists of four PCBA boards: a power board, a control board, a power supply board, and a display board. The main power circuit and related drive circuits are located on the power board; the main control chip and related peripheral circuits, signal sampling and detection circuits, and communication circuits are located on the control board; the 400V to 12V high-voltage bus power module is located on the power supply board; and LED signal indicators are located on the indicator board. The control board connects to the power board via a 2.54mm-28P dual-row pin header and a 2.54mm-28P female connector. The power supply board is designed with gold fingers and directly soldered onto the power board. The display board is connected via a ribbon cable using XH 2.54-5P terminals and is fixed to the casing to display the device's operating status.

[0055] Below are the detailed circuit diagrams for each functional module:

[0056] Figure 3This is the power circuit diagram for the voltage regulator. X1 to X4 are external power line terminals: X1 connects to the live wire input, X3 connects to the live wire output, X2 connects to the neutral wire, and X4 connects to the ground wire. A filter consisting of X and Y capacitors and a common-mode inductor is placed on the input and output sides to eliminate differential-mode and common-mode interference in the circuit. A fuse and varistor at the input end are used to prevent power grid surges from affecting the equipment, and in case of a short circuit due to equipment failure, the fuse will blow without affecting the power grid. An NTC thermistor R8 (47Ω at room temperature) is connected in series on the input live wire to limit the charging current of the bus capacitor C1 at power-on, preventing damage to the rectifier diodes by the instantaneous pulse current and affecting the tripping of the input-side circuit breaker. A current sensor is placed on both the input and output live wires to sample the input and output currents respectively. C7 on the input side is a 2.2uF X2 capacitor, providing instantaneous energy to the PFC and preventing the equipment from causing harmonic interference to the power grid. L1 is a PFC boost inductor with an inductance of 1.2mH. L2 and C9 on the output side form an LC filter with parameters of 1.2mH and 3.3uF, respectively. This filters the output SPWM pulse wave into a smooth sine wave for the load. VT1 to VT6 are power switching transistors, model NCE15TD60BF, which are 600V, 15A, TO-220F packaged field-cutoff high-frequency IGBTs, meeting performance requirements. VT1 and VT2 form the high-frequency bridge arm of the PFC, VT5 and VT6 form the high-frequency bridge arm of the inverter, and VT3 and VT4 form a shared power frequency bridge arm. Three sets of RC filters connected in parallel on the upper bridge arm are used to filter out voltage spikes during IGBT turn-off. C1 is a 330uF / 450V electrolytic capacitor, serving as a bus filter and energy storage unit. C2 and C4 are 100nF / 1kV ceramic capacitors, filtering out high-frequency noise from the bus.

[0057] Figure 4This is the IGBT driver circuit diagram. The driver circuit adopts a bootstrap scheme, requiring only one driver chip per bridge arm. Furthermore, all three bridge arm driver circuits share a single 12V power supply, significantly simplifying the circuit and reducing costs. The bootstrap chip is model EG2181D, suitable for circuits up to 600V, with a drive current of 2A (source current) and 2.5A (sink current), and a maximum supported frequency of 500kHz. PWMA and PMWB are input signals from the control board. A 1kΩ resistor and a 100pF capacitor provide some filtering for high-frequency interference in the input signal without causing excessive delay. A 10uF ceramic capacitor is connected in parallel to the VCC pin of Pin 5, providing good voltage regulation for the chip power supply and meeting the energy requirements for both low-side drive and high-side bootstrap charging. The 10uF bootstrap capacitor connected between Pin 6 and Pin 8 is sufficient to meet the energy requirements of the high-side IGBT even if the low-side is inactive for half a cycle and does not charge the bootstrap capacitor. The bootstrap diode type uses a fast recovery diode with a reverse withstand voltage of 1kV, and a 10Ω resistor in series to limit the peak charging current of the bootstrap capacitor.

[0058] Figure 5 The circuit diagram for bus pre-charge control shows that bus pre-charge is achieved by connecting an NTC thermistor R8 and a relay K1 in parallel and series on the input live wire. (See diagram...) Figure 6 Power schematic diagram. Upon power-on, the bus capacitor C1 is charged through R8. Once it reaches approximately the required voltage, relay K1 closes, short-circuiting R8. The control circuit is shown above. Figure 8 One end of the relay coil is connected to a 12V power supply, and the other end is connected to the collector of an NPN transistor. When the voltage level is high, the transistor conducts and the relay closes. The parallel-connected D6 provides a freewheeling path for the coil current when the relay is open, and the LED D7 indicates the relay's closed state.

[0059] Figure 6This is a voltage acquisition circuit diagram. The voltage regulator acquires the input voltage, output voltage, and bus voltage, all using a series large resistor to isolate high and low voltage signals. The series large resistor is located on the power board, and the signal is sent to the corresponding operational amplifier circuit on the control board for processing via a 2.54mm-28P connector. The bus voltage is obtained by voltage division using four 200kΩ and one 4.99kΩ resistors. This signal voltage is safe enough not to exceed the measurement range of subsequent circuits or damage subsequent processing circuits. After passing through an RC low-pass filter, it is followed by an operational amplifier and sent to the chip for sampling and processing. The input and output voltages are sampled differentially and biased by a 1.65V reference voltage. The signal processed by the operational amplifier is an AC sine wave signal superimposed on a 1.65V DC voltage for easy chip acquisition. By comparing the AC input voltage signal with a 1.65V reference, a zero-crossing detection synchronization signal is generated, allowing the control chip to synchronize the phase and frequency of the input voltage.

[0060] Figure 7 For the current acquisition and overcurrent detection circuit, a Hall effect current sensor (ACS712ELCTR-20A-T) is used on both the input and output sides to sample the input and output currents. The sampling current range is 20A, and the isolation voltage is 2.1kVrms, meeting the design requirements. Powered by 5V, the output signal is half the supply voltage (2.5V) when the input current is 0. The sensor signal is sent to the control board via a 2.54mm-28P connector. After voltage division by a 2kΩ and a 3kΩ resistor, the sampled signal is converted into an AC signal superimposed on a 1.5V DC base, facilitating chip sampling. A voltage regulator performs hardware overcurrent detection on both the input and output currents, increasing reliability.

[0061] Figure 8 The diagram shows the pinout of the main control chip. The main chip on the control board is an ST STM32G474RBT6, packaged in an LQFP-64F, with a clock frequency of 170MHz. The chip's high-resolution HRTIM timer can handle various complex PWM controls. Overcurrent detection signals are connected to pins Pin24 and Pin30, which have a global interrupt function for HRTIM faults, allowing for timely output blocking in case of overcurrent or short circuits. An external crystal oscillator with a frequency of 8MHz is used, and an EEPROM is used to store configuration parameters. The SWD interface is used for programming. Four LEDs are also placed on the control board to indicate relevant operating statuses, facilitating debugging and future maintenance.

[0062] Figure 9 The circuit diagram for the RS232 communication module shows that the voltage regulator has a reserved RS232 communication interface, which can be used for external communication, firmware upgrades, and connection to a display screen.

[0063] Figure 10 The power supply circuit diagram for the control board shows that 12V is converted to 5V via a linear regulator L78M05CDT-TR to power the signal acquisition and communication modules. The 5V is converted to 3.3V via a linear regulator LD1117AG to power the main control chip. The 3.3V is then divided by two 1kΩ resistors and followed by an operational amplifier to generate a 1.65V voltage to provide DC bias for AC signal acquisition.

[0064] Figure 11 This is the circuit diagram of the power supply module on the power board. The power supply is a simple counter-current switching power supply that converts the 400V bus voltage to a low voltage of 12V to power the voltage regulator.

[0065] Figure 12 This is the circuit diagram for the indicator light. Figure 12 P7 on the left is the terminal block on the power board, and P1 on the right is the terminal block on the indicator light board, connected via an XH2.54-5P ribbon cable.

[0066] The embodiments of the present invention have been described above. However, the embodiments are not limited to the specific implementation methods described above. The specific implementation methods described above are merely illustrative and not restrictive. Those skilled in the art can make more equivalent embodiments under the guidance of the present embodiments, and all of them are within the protection scope of the present embodiments.

Claims

1. An inverter-controlled constant voltage power supply device, characterized in that, include: Power board, control board, power supply board, and display board; The power board includes: a precharge module, a voltage regulator module, and a drive control module; The voltage regulator module includes a voltage regulator circuit, which includes: The input-side energy storage filter capacitor C1 is used to filter the input voltage. PFC boost inductor L1 is used for power factor correction and voltage boosting; Bus filter capacitor C3 is used to store and stabilize the DC bus voltage; The inverter output filter inductor L2 and filter capacitor C2 are used to filter the pulse waveform of the inverter output into a smooth sine wave; The six power switching transistors Q1 to Q6 and their corresponding body diodes D1 to D6 form three bridge arms: Q1 and Q2 form the PFC high-frequency bridge arm; Q3 and Q4 form the power frequency bridge arm, which serves as a shared bridge arm for PFC and inverter. Q5 and Q6 form the inverter high-frequency bridge arm; The control circuit is used to control the on / off state of each power switching transistor.

2. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The control board has a main control chip and peripheral circuits, a signal sampling and detection circuit, and a communication circuit.

3. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The power board has a bus high voltage 400V to low voltage 12V power module.

4. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The control circuit controls the voltage of the PFC boost inductor L1 by adjusting the duty cycle of the PFC high-frequency bridge arm switch, thereby adjusting the voltage of the bus filter capacitor C3 to keep the voltage of C3 stable.

5. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The control circuit controls the output voltage by adjusting the duty cycle of the inverter high-frequency bridge arm switching transistors, thereby stabilizing the output voltage.

6. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The voltage of the bus filter capacitor C3 is equal to the sum of the input voltage Ui and the voltage across the inductor when the PFC boost inductor L1 releases energy.

7. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The power switching transistors Q-Q6 are IGBTs, MOSFETs, or other power semiconductor devices.

8. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The body diodes D1-D6 are either internal body diodes of the power switching transistor or external diodes connected in parallel.

9. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, During each half-sine wave cycle of the high-frequency bridge arm, the two switching transistors of the high-frequency bridge arm operate in a complementary high-frequency switching mode.

10. The inverter-controlled constant voltage power supply device according to claim 1, characterized in that, The control circuit uses SPWM modulation to control the on and off of each power switch.

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