Pulse power supply with soft start function

Abstract

The utility model discloses a pulse power supply with a soft start function, which comprises a rectification inverter circuit and a chopper circuit, the rectification inverter circuit inputs power frequency alternating current and outputs controllable direct current, and the chopper circuit inputs controllable direct current and outputs pulse current; the inverter control circuit controls and outputs a pulse width driving signal to the rectification inverter circuit according to the voltage control signal; the voltage stabilization acquisition circuit is used for acquiring a voltage signal of the controllable direct current and outputting the voltage signal to the input comparison circuit; the soft start circuit is used for outputting a gradually changing reference voltage to the input comparison circuit according to a start signal; and the input comparison circuit is used for outputting a gradually-changed voltage control signal to the inversion control circuit according to the gradually-changed reference voltage, so that the duty ratio of the pulse width driving signal is gradually increased, and a soft starting function is realized. The beneficial effects are that smooth starting of the pulse power supply is realized and a voltage stabilization function is possessed.

Description

Technical Field

[0001] The utility model relates to the technical field of pulse power supplies, in particular to a pulse power supply with a soft start function. Background Art

[0002] High-frequency pulse power supply is suitable for electroplating gold, silver, nickel, tin, and alloys, and can significantly improve the functionality of the coating. It includes a rectifier and inverter circuit that converts industrial frequency AC power into DC power, and a chopper circuit that converts DC power into pulse power. By controlling the duty cycle of the pulse width drive signal sent to the rectifier and inverter circuit, the current and voltage of the DC power can be controlled.

[0003] By directly setting the duty cycle of the pulse width drive signal, the final output pulse power reaches the required voltage or current. However, when the duty cycle is directly set, the voltage or current of the DC power will quickly reach the value corresponding to the duty cycle. First, it is open-loop control, and the DC power has no voltage or current stabilization function. Second, it quickly reaches the set value and does not implement the soft start function, which may damage the equipment using the pulse power supply.

[0004] The disadvantage of the existing technology is that the soft start function is not realized. Utility Model Content

[0005] In view of at least one defect of the prior art, the purpose of the present invention is to provide a pulse power supply with a soft start function, which can achieve smooth start-up of the pulse power supply and has a voltage stabilization function.

[0006] In order to achieve the above object, the utility model adopts the following technical solution: a pulse power supply with a soft start function, comprising a rectifier inverter circuit and a chopper circuit, the rectifier inverter circuit inputs industrial frequency AC power and outputs controllable DC power, the chopper circuit inputs controllable DC power and outputs pulse power;

[0007] The inverter control circuit also includes an inverter control circuit, which inputs a voltage control signal and outputs a pulse width drive signal to the rectifier inverter circuit, controls the duty cycle of the pulse width drive signal according to the voltage control signal, and further controls the voltage and current of the controllable direct current;

[0008] The key is: it also includes voltage stabilization acquisition circuit, soft start circuit and input comparison circuit;

[0009] The voltage stabilization acquisition circuit is used to: collect the voltage signal of the controllable direct current and output it to the input comparison circuit;

[0010] The soft start circuit is used to: output a gradually changing reference voltage to the input comparison circuit according to the start signal;

[0011] Input comparison circuit: outputs a gradually changing voltage control signal to the inverter control circuit according to the gradually changing reference voltage, thereby gradually increasing the duty cycle of the pulse width drive signal to achieve a soft start function.

[0012] The voltage stabilization acquisition circuit, input comparison circuit, inverter control circuit and rectifier inverter circuit form a closed-loop control circuit for controllable DC power, realizing the automatic voltage stabilization function;

[0013] The voltage of the controllable DC power is set by the reference voltage. A gradually changing reference voltage is output through the soft start circuit to achieve a gradual increase in the controllable DC power, thereby realizing the smooth start of the pulse power supply; when the voltage stabilization acquisition circuit is replaced with a current stabilization acquisition circuit to collect the current signal of the controllable DC power, a smooth start of the current mode can be achieved.

[0014] Furthermore, the soft start circuit includes a drive isolation circuit, a charge and discharge circuit and a follower regulation circuit;

[0015] The driving isolation circuit is used to: obtain the start signal, and control the on and off of the transistor Q11 after driving and isolating;

[0016] The charge and discharge circuit is used to charge and discharge the capacitor C903 according to the on-off change of the transistor Q11, and then output a gradually changing charge and discharge voltage to the follower regulation circuit;

[0017] The follower regulation circuit is used to convert the gradually changing charge and discharge voltage into the gradually changing reference voltage, and adjust the threshold of the reference voltage by adjusting the adjustable resistor VR14.

[0018] By driving the isolation circuit, the disadvantage of insufficient driving capability of the start signal is avoided, and isolation is formed with the circuit that generates the start signal, such as a single-chip microcomputer, to avoid interference from the charge and discharge circuit during charging or discharging; the charge and discharge circuit obtains a gradually changing voltage through capacitor charging and discharging, but the voltage is not within the required voltage range, such as from -1V to -12V. The follower adjustment circuit converts it into a standard voltage range, such as 0V-5V, and adjusts the sliding end of the adjustable resistor VR14 to adjust the threshold of the reference voltage, ultimately achieving a gradual increase in the duty cycle of the pulse width drive signal from zero. The final voltage of the controllable DC power after startup is determined by the threshold of the reference voltage.

[0019] The drive isolation circuit mainly includes a transistor Q13 and an optocoupler U19. The positive electrode of the diode D903 inputs the start signal, the negative electrode of the diode D903 is connected to the base of the transistor Q13 in series with a resistor R911; the negative electrode of the diode D903 is connected to ground in series with a resistor R912, and the negative electrode of the diode D903 is connected to ground in series with a capacitor C904.

[0020] The +12V power supply end is connected to the front end of the resistor R910, the back end of the resistor R910 is connected to the positive input end of the optocoupler U19, the negative input end of the optocoupler U19 is connected to the collector of the transistor Q13, and the emitter of the transistor Q13 is grounded;

[0021] The positive output terminal of the optocoupler U19 is connected to the +12V power supply terminal, and the negative output terminal of the optocoupler U19 is connected in series with the resistor R909 and then connected to the base of the transistor Q11;

[0022] The charging and discharging circuit mainly includes an operational amplifier U18 and a capacitor C903, a +12V power supply end connected to the front end of an adjustable resistor VR13, a rear end of the adjustable resistor VR13 connected in series with a resistor R906 and then grounded, a sliding end of the adjustable resistor VR13 connected in series with a resistor R907 connected to the reverse end of the operational amplifier U18, the same-direction end of the operational amplifier U18 is grounded, a capacitor C903 is connected in parallel between the reverse end and the output end of the operational amplifier U18, the reverse end of the operational amplifier U18 is connected to the front end of the resistor R908, the rear end of the resistor R908 is connected to the collector of the transistor Q11, and the emitter of the transistor Q11 is connected to the output end of the operational amplifier U18;

[0023] The operational amplifier U18 is powered by +12V and -12V. When the transistor Q11 changes from the on state to the off state, the output voltage of the operational amplifier U18 gradually decreases to -12V.

[0024] The following regulation circuit mainly includes a voltage stabilizing diode D902, an operational amplifier U15A, a transistor Q12, a resistor R903 and an adjustable resistor VR14;

[0025] The output end of the operational amplifier U18 is connected to the front end of the resistor R916, the rear end of the resistor R916 is connected to the positive electrode of the voltage zener diode D902, and the negative electrode of the voltage zener diode D902 is grounded;

[0026] The common terminal of the resistor R906 and the Zener diode D902 is connected to the inverting terminal of the operational amplifier U15A, the non-inverting terminal of the operational amplifier U15A is grounded, the output terminal of the operational amplifier U15A is connected to the front end of the resistor R901, the rear end of the resistor R901 is connected to the base of the transistor Q12, the emitter of the transistor Q12 is connected to the front end of the resistor R903, the rear end of the resistor R903 is connected to the inverting terminal of the operational amplifier U15A; the inverting terminal of the operational amplifier U15A is connected to the cathode of the diode D901;

[0027] The collector of the transistor Q12 is connected to a +12V power supply terminal via a resistor R902, the emitter of the transistor Q12 is connected to the front end of an adjustable resistor VR14, the rear end of the adjustable resistor VR14 is grounded, and the sliding end of the adjustable resistor VR14 outputs the reference voltage; the emitter of the transistor Q12 is connected to a capacitor C902 via a resistor R905 via a resistor R905 connected to a ground;

[0028] The output terminal of the operational amplifier U18 changes from 0V to -5V, the reverse terminal voltage of the operational amplifier U15A also changes from 0V to -5V, the emitter voltage of the transistor Q12 changes from 0V to 5V, and the voltage across the adjustable resistor VR14 also changes from 0V to 5V;

[0029] When the output voltage of the operational amplifier U18 changes from -5V to -12V, due to the presence of the voltage stabilizing diode D902, the reverse terminal voltage of the operational amplifier U15A is always -5V, and the voltage across the adjustable resistor VR14 remains unchanged at 5V.

[0030] By adjusting the sliding end of the adjustable resistor VR14, the threshold of the reference voltage can be adjusted.

[0031] By inputting a start signal into the soft start circuit, the soft start circuit outputs a gradually rising reference voltage, and then by controlling the duty cycle of the pulse width drive signal to gradually increase, a smooth start function is achieved.

[0032] Furthermore, the input comparison circuit mainly includes an operational amplifier U5A;

[0033] The reference voltage is input to the front end of the resistor R307, the rear end of the resistor R307 is connected to the front end of the resistor R308, the rear end of the resistor R308 is grounded, the common end of the resistor R307 and the resistor R308 is connected in series with the resistor R309 and then connected to the reverse end of the operational amplifier U5A, the non-inverting end of the operational amplifier U5A is connected to the output end of the voltage stabilization and acquisition circuit, the output end of the operational amplifier U5A is connected to the positive electrode of the diode D304, and the negative electrode of the diode D304 outputs the voltage control signal;

[0034] The voltage stabilization acquisition circuit mainly includes an operational amplifier U9;

[0035] The front end of the resistor R501 inputs the voltage signal of the controllable direct current, the rear end of the resistor R501 is connected to the front end of the adjustable resistor VR2, the rear end of the adjustable resistor VR2 is connected in series with a resistor R502 and then grounded, the sliding end of the adjustable resistor VR2 is connected to the front end of the resistor R503, the rear end of the resistor R503 is connected in series with a resistor R504 and then grounded, and the common end of the resistor R503 and the resistor R504 is connected in series with a resistor R506 and then connected to the same-direction end of the operational amplifier U9;

[0036] The reverse end of the operational amplifier U9 is connected in series with a resistor R507 and then grounded; between the output end and the reverse end of the operational amplifier U9, a resistor R508 and a capacitor C503 are connected in parallel; the output end of the operational amplifier U9 is connected to the positive electrode of the diode R510, and the negative electrode of the diode R510 is connected to the positive end of the operational amplifier U5A;

[0037] The two zero-adjustment bias terminals of the operational amplifier U9 are connected to the two ends of the adjustable resistor VR1. The sliding terminal of the adjustable resistor VR1 is connected in series with the resistor R509 and then connected to the -12V power supply terminal.

[0038] Furthermore, the inverter control circuit includes a pulse width modulation circuit and a pulse width drive circuit;

[0039] After the pulse width modulation circuit inputs the voltage control signal, it outputs a pulse width control signal; after the inverter drive circuit inputs the pulse width control signal, it outputs a pulse width drive signal;

[0040] The pulse width modulation circuit is used to: control the duty cycle of the pulse width control signal according to the voltage control signal;

[0041] The pulse width drive circuit is used to: isolate and improve the driving capability of the pulse width drive signal.

[0042] Since the switching tubes in the rectifier and inverter circuits have high power and are fragile devices, directly using a pulse width modulation circuit for control will firstly result in insufficient driving capability and secondly easily damage the pulse width modulation circuit and other circuits connected to the pulse width modulation circuit. However, using a pulse width drive circuit can achieve isolation and improve the driving capability of the pulse width drive signal.

[0043] Furthermore, the pulse width modulation circuit includes a pulse width modulation chip U4, and the model of the pulse width modulation chip U4 is SW494;

[0044] The +V1 terminal of the pulse width modulation chip U4 is connected to a resistor R302 in series and then to ground. The +V2 terminal of the pulse width modulation chip U4 is connected to a resistor R301 in series and then to ground. The -V1 terminal and -V2 terminal of the pulse width modulation chip U4 are connected to a resistor R303 in series and then to ground. The voltage control signal is input to the +V1 terminal or the +V2 terminal of the pulse width modulation chip U4.

[0045] The E1 and E2 terminals of the pulse width modulation chip U4 output two sets of pulse width control signals with complementary dead zones;

[0046] Short-circuit the first and third pins of terminal group JP7 to ground the E1 and E2 terminals of the pulse width modulation chip U4, forcing the duty cycle to zero.

[0047] By using a complementary pulse width control signal with a dead zone, current conflicts and short circuits caused by the conduction and switching of the switch tubes in the rectifier inverter circuit can be avoided.

[0048] Furthermore, the -V1 and -V2 terminals of the pulse width modulation chip U4 are connected in series with capacitors C304 and then grounded; the +V1 terminal of the pulse width modulation chip U4 is connected in series with capacitors C303 and then grounded; the +V2 terminal of the pulse width modulation chip U4 is connected in series with capacitors C301 and then grounded; and the +V2 terminal of the pulse width modulation chip U4 is connected in series with capacitors C302 and then grounded.

[0049] The voltage control signal input from the +V1 terminal of the pulse width modulation chip U4 is filtered through capacitor C303, and the voltage control signal input from the +V2 terminal of the pulse width modulation chip U4 is filtered and prevented from sudden changes through capacitors C301 and C302.

[0050] Furthermore, the pulse width driving circuit includes an optocoupler isolation chip U1;

[0051] The E1 terminal of the pulse width modulation chip U4 is connected to the front end of the resistor R103, the rear end of the resistor R103 is connected to the positive input terminal of the optocoupler isolation chip U1, and the negative input terminal of the optocoupler isolation chip U1 is grounded;

[0052] The output end of the optocoupler isolation chip U1 is connected to the base of the NPN transistor Q1 and the PNP transistor Q2, the +20V power supply end is connected to the collector of the transistor Q1, the emitter of the transistor Q1 is connected to the emitter of the transistor Q2, and the collector of the transistor Q2 is grounded; the common end of the transistor Q1 and the transistor Q2 outputs the pulse width drive signal.

[0053] The isolation function is achieved through the optocoupler isolation chip of the pulse width drive circuit, and the driving capability of the pulse width drive signal is enhanced through the push-pull output circuit composed of NPN type transistors and PNP type transistors.

[0054] Furthermore, the +20V power supply terminal is connected to the front end of the resistor R101, the rear end of the resistor R101 is connected in series with a reverse voltage zener diode D101 and then grounded, and the common end of the resistor R101 and the voltage zener diode D101 is connected to the second pin of the terminal group JP1;

[0055] The common end of the transistor Q1 and the transistor Q2 is connected to the front end of the resistor R107, the rear end of the resistor R107 is connected to the front end of the resistor R108, and the rear end of the resistor R108 is connected to the second pin of the terminal group JP1; the common end of the resistor R107 and the resistor R108 is connected to the first pin of the terminal group JP1;

[0056] A bidirectional voltage regulator diode DW1 is connected in series between the first and second pins of the terminal group JP1;

[0057] When the transistor Q1 is turned on, a positive voltage is applied between the first pin and the second pin of the terminal group JP1; when the transistor Q2 is turned on, a negative voltage is applied between the first pin and the second pin of the terminal group JP1;

[0058] The first pin and the second pin of the terminal group JP1 output a group of pulse width driving signals.

[0059] When the transistor Q2 is turned on, a negative voltage is present between the first and second pins of the terminal group JP1, realizing the reverse shutdown function of the pulse width drive signal. The reverse shutdown voltage value of the pulse width drive signal is the regulated voltage value of the Zener diode D101, and the forward conduction voltage value of the pulse width drive signal is the regulated voltage value of the bidirectional Zener diode DW1.

[0060] Furthermore, the collector series capacitor C101 of the transistor Q1 is connected to the collector of the transistor Q2; the collector series capacitor C102 of the transistor Q1 is connected to the collector of the transistor Q2; the reverse voltage zener diode D101 is connected in parallel with the capacitor C103; and the reverse voltage zener diode D101 is connected in parallel with the capacitor C104.

[0061] The capacitors C103 and C104 can filter the signal output from the first pin of the terminal group JP1 and smooth the startup impact; the capacitors C103 and C104 can filter the signal output from the second pin of the terminal group JP1 and smooth the startup impact.

[0062] Significant effect: The utility model provides a pulse power supply with a soft start function, which can smoothly start the direct current input to the chopper circuit and also has a voltage stabilization function. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Figure 1 This is a module structure diagram of the utility model;

[0064] Figure 2 This is the schematic diagram of the rectifier inverter circuit;

[0065] Figure 3 This is the schematic diagram of the pulse width modulation circuit;

[0066] Figure 4 This is the schematic diagram of the pulse width drive circuit;

[0067] Figure 5 This is the schematic diagram of the soft start circuit;

[0068] Figure 6 This is the schematic diagram of the input comparison circuit;

[0069] Figure 7 This is the schematic diagram of the voltage stabilization acquisition circuit. DETAILED DESCRIPTION

[0070] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0071] like Figure 1 As shown, a pulse power supply with a soft start function includes a rectifier inverter circuit and a chopper circuit. The rectifier inverter circuit inputs industrial frequency AC power and outputs controllable DC power. The chopper circuit inputs controllable DC power and outputs pulse power.

[0072] The inverter control circuit also includes an inverter control circuit, which inputs a voltage control signal and outputs a pulse width drive signal to the rectifier inverter circuit, controls the duty cycle of the pulse width drive signal according to the voltage control signal, and further controls the voltage and current of the controllable direct current;

[0073] It also includes a voltage stabilization acquisition circuit, a soft start circuit and an input comparison circuit;

[0074] The voltage stabilization acquisition circuit is used to: collect the voltage signal of the controllable direct current and output it to the input comparison circuit;

[0075] The soft start circuit is used to: output a gradually changing reference voltage to the input comparison circuit according to the start signal;

[0076] Input comparison circuit: outputs a gradually changing voltage control signal to the inverter control circuit according to the gradually changing reference voltage, thereby gradually increasing the duty cycle of the pulse width drive signal to achieve a soft start function.

[0077] The voltage of the controllable DC power is set by the reference voltage. A gradually changing reference voltage is output through the soft start circuit to achieve a gradual increase in the controllable DC power, thereby realizing the smooth start of the pulse power supply; when the voltage stabilization acquisition circuit is replaced with a current stabilization acquisition circuit to collect the current signal of the controllable DC power, a smooth start of the current mode can be achieved.

[0078] It also includes a low-power power supply, which uses existing mature technology to provide +20V power supply end, +12V power supply end, -12V power supply end, and L5V power supply end to power the inverter control circuit, voltage stabilization acquisition circuit, soft start circuit and input comparison circuit.

[0079] The rectifier and inverter circuit includes an industrial frequency rectifier circuit, a first filter circuit, a high frequency inverter circuit, a high frequency rectifier circuit, and a second filter circuit connected in sequence;

[0080] The power frequency rectifier circuit is used to: rectify the input three-phase AC power;

[0081] The first filter circuit is used to filter out the three-phase ripple generated after rectification by the power frequency rectification circuit.

[0082] The high-frequency inverter circuit is used to: invert the direct current output by the first filter circuit into high-frequency alternating current according to the pulse width drive signal, and perform voltage boosting or voltage reduction;

[0083] High-frequency rectifier circuit is used to: rectify high-frequency AC power into DC power;

[0084] The second filter circuit is used to filter out the high-frequency ripple generated after rectification by the high-frequency rectification circuit and output the controllable direct current.

[0085] like Figure 2As shown, the power frequency rectifier circuit is a three-phase full-bridge rectifier circuit composed of diode D91, diode D92, diode D93, diode D94, diode D5 and diode D6. The power frequency rectifier circuit inputs three-phase AC power and outputs DC power with three-phase ripple.

[0086] The first filter circuit is composed of an inductor L11, a capacitor C11 and a capacitor C12, and filters the DC power with three-phase ripple;

[0087] The high-frequency inverter circuit is composed of switching tubes IGBT1, IGBT2, IGBT3, IGBT4, an overcurrent sampling resistor R815, and a transformer T1. The inverter circuit composed of switching tubes IGBT1, IGBT2, IGBT3, and IGBT4 inverts the DC power output by the first filter circuit into high-frequency AC power, which is then stepped up or down by transformer T1. The overcurrent sampling resistor R815 can perform current sampling on the inverted high-frequency AC power.

[0088] The high-frequency rectifier circuit mainly includes diode D96 and diode D97. The two ends of the secondary side of transformer T1 are connected to the positive electrodes of diode D96 and diode D97 respectively. The negative electrodes of diode D96 and diode D97 serve as the positive output terminal of the high-frequency rectifier circuit. The center tap of the secondary side of transformer T1 serves as the negative output terminal of the high-frequency rectifier circuit. The high-frequency rectifier circuit rectifies the high-frequency AC power that has been stepped up or down by transformer T1 into DC power with high-frequency ripple.

[0089] The second filter circuit mainly includes an inductor L12, which filters out high-frequency ripples so that the controllable DC power it outputs has no ripples.

[0090] By inputting a set of pulse width drive signals to the gates of IGBT1 and IGBT4, or inputting another set of pulse width drive signals to the gates of IGBT2 and IGBT3, the controllable DC power output by the second filter circuit can be controlled. The two sets of pulse width drive signals are complementary and have dead zones. When the duty cycle of the pulse width drive signal is zero, the high-frequency inverter circuit stops inverting, and the voltage and current of the controllable DC power output are zero.

[0091] The pulse width drive signal is output by the inverter control circuit, and the duty cycle of the pulse width drive signal is controlled by the voltage control signal input to the inverter control circuit;

[0092] like Figure 1 As shown, the inverter control circuit includes a pulse width modulation circuit and a pulse width drive circuit;

[0093] After the pulse width modulation circuit inputs the voltage control signal, it outputs a pulse width control signal; after the inverter drive circuit inputs the pulse width control signal, it outputs a pulse width drive signal;

[0094] The pulse width modulation circuit is used to: control the duty cycle of the pulse width control signal according to the voltage control signal;

[0095] The pulse width drive circuit is used to: isolate and improve the driving capability of the pulse width drive signal.

[0096] Since the switching tubes in the rectifier and inverter circuits have high power and are fragile devices, when the pulse width modulation circuit is directly used for control, firstly, the driving capability is insufficient, and secondly, the pulse width modulation circuit and other circuits connected to the pulse width modulation circuit are easily damaged. However, the pulse width drive circuit not only achieves isolation, but also improves the driving capability of the pulse width drive signal.

[0097] like Figure 3 As shown, the pulse width modulation circuit includes a pulse width modulation chip U4, and the model of the pulse width modulation chip U4 is SW494;

[0098] The +V1 terminal of the pulse width modulation chip U4 is connected to a resistor R302 in series and then to ground. The +V2 terminal of the pulse width modulation chip U4 is connected to a resistor R301 in series and then to ground. The -V1 terminal and -V2 terminal of the pulse width modulation chip U4 are connected to a resistor R303 in series and then to ground. The voltage control signal is input to the +V1 terminal or the +V2 terminal of the pulse width modulation chip U4.

[0099] The E1 and E2 terminals of the pulse width modulation chip U4 output two sets of pulse width control signals with complementary dead zones;

[0100] The RT end of the pulse width modulation chip U4 is connected to the front end of the resistor R305, the rear end of the resistor R305 is connected to the front end of the resistor R306, and the rear end of the resistor R306 is grounded; the CT end of the pulse width modulation chip U4 is connected in series with the capacitor C306 and then grounded, the VREF end of the pulse width modulation chip U4 is connected to the front end of the resistor R330, the rear end of the resistor R330 is connected to the front end of the resistor R304, and the rear end of the resistor R304 is grounded, and the common end of the resistor R330 and the resistor R304 is connected to the DTC end of the pulse width modulation chip U4; the VREF end and the 0C end of the pulse width modulation chip U4 are connected to the L5V power supply end;

[0101] By adjusting the capacitance or resistance of capacitor C306, resistor R305 and resistor R306, the frequency of the pulse width control signal is adjusted; by adjusting the resistance of resistor R330 and resistor R304, the dead time of the pulse width control signal output from the E1 terminal and the E2 terminal of the pulse width modulation chip U4 is adjusted;

[0102] By adjusting the voltage control signal input to the +V1 terminal or the +V2 terminal of the pulse width modulation chip U4, the duty cycle of the pulse width control signal output from the E1 terminal and the E2 terminal of the pulse width modulation chip U4 is adjusted;

[0103] By using a complementary pulse width control signal with a dead zone, current conflicts and short circuits caused by the conduction and switching of the switch tubes in the rectifier inverter circuit can be avoided.

[0104] The E1 terminal of the pulse width modulation chip U4 is connected to the anode of the diode D301, the E2 terminal of the pulse width modulation chip U4 is connected to the anode of the diode D302, the cathode of the diode D301 is connected to the cathode of the diode D302, the common terminal of the diode D301 and the diode D302 is connected in series with a resistor R313 and then grounded, the common terminal of the diode D301 and the diode D302 is connected to the first pin of the terminal group JP7, and the third pin of the terminal group JP7 is grounded;

[0105] Short-circuit the first and third pins of terminal group JP7 to ground the E1 and E2 terminals of the pulse width modulation chip U4, forcing the duty cycle to zero.

[0106] The -V1 and -V2 terminals of the pulse width modulation chip U4 are connected in series with capacitors C304 and then grounded; the +V1 terminal of the pulse width modulation chip U4 is connected in series with capacitors C303 and then grounded; the +V2 terminal of the pulse width modulation chip U4 is connected in series with capacitors C301 and then grounded; the +V2 terminal of the pulse width modulation chip U4 is connected in series with capacitors C302 and then grounded.

[0107] The voltage control signal input from the +V1 terminal of the pulse width modulation chip U4 is filtered through the capacitor C303, and the voltage control signal input from the +V2 terminal of the pulse width modulation chip U4 is filtered through the capacitors C301 and C302.

[0108] like Figure 4 As shown, the pulse width driving circuit includes two groups of isolated driving circuits with the same structure. Taking the first group of isolated driving circuits as an example:

[0109] The E1 terminal of the pulse width modulation chip U4 is connected to the front end of the resistor R103, the rear end of the resistor R103 is connected to the positive input terminal of the optocoupler isolation chip U1, and the negative input terminal of the optocoupler isolation chip U1 is grounded;

[0110] The output end of the optocoupler isolation chip U1 is connected to the base of the NPN transistor Q1 and the PNP transistor Q2, the +20V power supply end is connected to the collector of the transistor Q1, the emitter of the transistor Q1 is connected to the emitter of the transistor Q2, and the collector of the transistor Q2 is grounded; the common end of the transistor Q1 and the transistor Q2 outputs the pulse width drive signal;

[0111] The isolation function is achieved through the optocoupler isolation chip of the pulse width drive circuit, and the driving capability of the pulse width drive signal is enhanced through the push-pull output circuit composed of NPN type transistors and PNP type transistors.

[0112] The +20V power supply terminal is connected to the front end of the resistor R101, the rear end of the resistor R101 is connected in series with a reverse voltage zener diode D101 and then grounded, and the common end of the resistor R101 and the voltage zener diode D101 is connected to the second pin of the terminal group JP1;

[0113] The common end of the transistor Q1 and the transistor Q2 is connected to the front end of the resistor R107, the rear end of the resistor R107 is connected to the front end of the resistor R108, and the rear end of the resistor R108 is connected to the second pin of the terminal group JP1; the common end of the resistor R107 and the resistor R108 is connected to the first pin of the terminal group JP1;

[0114] A bidirectional voltage regulator diode DW1 is connected in series between the first and second pins of the terminal group JP1;

[0115] When the transistor Q1 is turned on, a positive voltage is applied between the first pin and the second pin of the terminal group JP1; when the transistor Q2 is turned on, a negative voltage is applied between the first pin and the second pin of the terminal group JP1;

[0116] The first pin and the second pin of the terminal group JP1 output a group of pulse width driving signals.

[0117] When the transistor Q2 is turned on, a negative voltage is present between the first and second pins of the terminal group JP1, realizing the reverse shutdown function of the pulse width drive signal. The reverse shutdown voltage value of the pulse width drive signal is the regulated voltage value of the Zener diode D101, and the forward conduction voltage value of the pulse width drive signal is the regulated voltage value of the bidirectional Zener diode DW1.

[0118] The collector series capacitor C101 of the transistor Q1 is connected to the collector of the transistor Q2; the collector series capacitor C102 of the transistor Q1 is connected to the collector of the transistor Q2; the reverse voltage zener diode D101 is connected in parallel with the capacitor C103; the reverse voltage zener diode D101 is connected in parallel with the capacitor C104.

[0119] The capacitors C103 and C104 can filter the signal output from the first pin of the terminal group JP1 and smooth the startup impact; the capacitors C103 and C104 can filter the signal output from the second pin of the terminal group JP1 and smooth the startup impact.

[0120] like Figure 5 As shown, the soft start circuit includes a drive isolation circuit, a charge and discharge circuit and a follower regulation circuit;

[0121] The driving isolation circuit is used to: obtain the start signal, and control the on and off of the transistor Q11 after driving and isolating;

[0122] The charge and discharge circuit is used to charge and discharge the capacitor C903 according to the on-off change of the transistor Q11, and then output a gradually changing charge and discharge voltage to the follower regulation circuit;

[0123] The follower regulation circuit is used to convert the gradually changing charge and discharge voltage into the gradually changing reference voltage, and adjust the threshold of the reference voltage by adjusting the adjustable resistor VR14.

[0124] By driving the isolation circuit, the disadvantage of insufficient driving capability of the start signal is avoided, and isolation is formed with the circuit that generates the start signal, such as a single-chip microcomputer, to avoid interference from the charge and discharge circuit during charging or discharging; the charge and discharge circuit obtains a gradually changing voltage through capacitor charging and discharging, but the voltage is not within the required voltage range, such as from -1V to -12V. The follower adjustment circuit converts it into a standard voltage range, such as 0V-5V, and adjusts the sliding end of the adjustable resistor VR14 to adjust the threshold of the reference voltage, ultimately achieving a gradual increase in the duty cycle of the pulse width drive signal from zero. The final voltage of the controllable DC power after startup is determined by the threshold of the reference voltage.

[0125] The drive isolation circuit mainly includes a transistor Q13 and an optocoupler U19. The positive electrode of the diode D903 inputs the start signal, the negative electrode of the diode D903 is connected to the base of the transistor Q13 in series with a resistor R911; the negative electrode of the diode D903 is connected to ground in series with a resistor R912, and the negative electrode of the diode D903 is connected to ground in series with a capacitor C904.

[0126] The +12V power supply end is connected to the front end of the resistor R910, the back end of the resistor R910 is connected to the positive input end of the optocoupler U19, the negative input end of the optocoupler U19 is connected to the collector of the transistor Q13, and the emitter of the transistor Q13 is grounded;

[0127] The positive output terminal of the optocoupler U19 is connected to the +12V power supply terminal, and the negative output terminal of the optocoupler U19 is connected in series with the resistor R909 and then connected to the base of the transistor Q11;

[0128] The charging and discharging circuit mainly includes an operational amplifier U18 and a capacitor C903, a +12V power supply end connected to the front end of an adjustable resistor VR13, a rear end of the adjustable resistor VR13 connected in series with a resistor R906 and then grounded, a sliding end of the adjustable resistor VR13 connected in series with a resistor R907 connected to the reverse end of the operational amplifier U18, the same-direction end of the operational amplifier U18 is grounded, a capacitor C903 is connected in parallel between the reverse end and the output end of the operational amplifier U18, the reverse end of the operational amplifier U18 is connected to the front end of the resistor R908, the rear end of the resistor R908 is connected to the collector of the transistor Q11, and the emitter of the transistor Q11 is connected to the output end of the operational amplifier U18;

[0129] The operational amplifier U18 is powered by +12V and -12V. When the transistor Q11 changes from the on state to the off state, the output voltage of the operational amplifier U18 gradually decreases to -12V.

[0130] The following regulation circuit mainly includes a voltage stabilizing diode D902, an operational amplifier U15A, a transistor Q12, a resistor R903 and an adjustable resistor VR14;

[0131] The output end of the operational amplifier U18 is connected to the front end of the resistor R916, the rear end of the resistor R916 is connected to the positive electrode of the voltage zener diode D902, and the negative electrode of the voltage zener diode D902 is grounded;

[0132] The common terminal of the resistor R906 and the Zener diode D902 is connected to the inverting terminal of the operational amplifier U15A, the non-inverting terminal of the operational amplifier U15A is grounded, the output terminal of the operational amplifier U15A is connected to the front end of the resistor R901, the rear end of the resistor R901 is connected to the base of the transistor Q12, the emitter of the transistor Q12 is connected to the front end of the resistor R903, the rear end of the resistor R903 is connected to the inverting terminal of the operational amplifier U15A; the inverting terminal of the operational amplifier U15A is connected to the cathode of the diode D901;

[0133] The collector of the transistor Q12 is connected to a +12V power supply terminal via a resistor R902, the emitter of the transistor Q12 is connected to the front end of an adjustable resistor VR14, the rear end of the adjustable resistor VR14 is grounded, and the sliding end of the adjustable resistor VR14 outputs the reference voltage; the emitter of the transistor Q12 is connected to a capacitor C902 via a resistor R905 via a resistor R905 connected to a ground;

[0134] The output terminal of the operational amplifier U18 changes from 0V to -5V, the reverse terminal voltage of the operational amplifier U15A also changes from 0V to -5V, the emitter voltage of the transistor Q12 changes from 0V to 5V, and the voltage across the adjustable resistor VR14 also changes from 0V to 5V;

[0135] When the output voltage of the operational amplifier U18 changes from -5V to -12V, due to the presence of the voltage stabilizing diode D902, the reverse terminal voltage of the operational amplifier U15A is always -5V, and the voltage across the adjustable resistor VR14 remains unchanged at 5V.

[0136] By adjusting the sliding end of the adjustable resistor VR14, the threshold of the reference voltage can be adjusted.

[0137] By inputting a start signal into the soft start circuit, the soft start circuit outputs a gradually rising reference voltage, and then by controlling the duty cycle of the pulse width drive signal to gradually increase, a smooth start function is achieved.

[0138] like Figure 6 As shown, the input comparison circuit mainly includes an operational amplifier U5A;

[0139] The reference voltage is input to the front end of the resistor R307, the rear end of the resistor R307 is connected to the front end of the resistor R308, the rear end of the resistor R308 is grounded, the common end of the resistor R307 and the resistor R308 is connected in series with the resistor R309 and then connected to the reverse end of the operational amplifier U5A, the non-inverting end of the operational amplifier U5A is connected to the output end of the voltage stabilization and acquisition circuit, the output end of the operational amplifier U5A is connected to the positive electrode of the diode D304, and the negative electrode of the diode D304 outputs the voltage control signal;

[0140] like Figure 7 As shown, the voltage stabilization acquisition circuit mainly includes the operational amplifier U9;

[0141] The front end of the resistor R501 inputs the voltage signal of the controllable direct current, the rear end of the resistor R501 is connected to the front end of the adjustable resistor VR2, the rear end of the adjustable resistor VR2 is connected in series with a resistor R502 and then grounded, the sliding end of the adjustable resistor VR2 is connected to the front end of the resistor R503, the rear end of the resistor R503 is connected in series with a resistor R504 and then grounded, and the common end of the resistor R503 and the resistor R504 is connected in series with a resistor R506 and then connected to the same-direction end of the operational amplifier U9;

[0142] The reverse end of the operational amplifier U9 is connected in series with a resistor R507 and then grounded; between the output end and the reverse end of the operational amplifier U9, a resistor R508 and a capacitor C503 are connected in parallel; the output end of the operational amplifier U9 is connected to the positive electrode of the diode R510, and the negative electrode of the diode R510 is connected to the positive end of the operational amplifier U5A;

[0143] The two zero-adjustment bias terminals of the operational amplifier U9 are connected to the two ends of the adjustable resistor VR1. The sliding terminal of the adjustable resistor VR1 is connected in series with the resistor R509 and then connected to the -12V power supply terminal.

[0144] like Figure 5 As shown, the soft start circuit input terminal B3 inputs the start signal, which is a pulse directly given by the single chip microcomputer. The output terminal CT of the soft start circuit outputs a gradually rising reference voltage to the Figure 6 The input comparison circuit is divided and fed to the reverse end of the op amp U5A. Figure 6 The same-direction end of the op amp U5A is connected to Figure 7 The output end of the medium voltage stabilization acquisition circuit;

[0145] Figure 6 The output of the op amp U5A outputs a voltage-controlled signal to Figure 3 The pulse width modulation circuit in; Figure 3 The E1 and E2 terminals of the pulse width modulation circuit output two sets of complementary pulse width control signals with dead zones to Figure 4 Pulse width drive circuit in; Select Figure 4 The first and second pins of the middle group JP1 drive Figure 2 IGBT1 and IGBT4, Figure 2 The current on the primary side of the transformer flows in the forward direction, or select Figure 4 The third and fourth pins of the mid-range group JP1 drive Figure 2 IGBT2 and IGBT3, Figure 2 The current on the primary side of the transformer flows in the reverse direction.

[0146] Finally, it should be noted that the above examples are only specific implementation examples of the present invention. Of course, those skilled in the art can make changes and modifications to the present invention. If these modifications and modifications fall within the scope of the claims of the present invention and their equivalent technologies, they should be considered to be within the scope of protection of the present invention.

Claims

1. A pulse power supply with a soft start function, comprising a rectifier and inverter circuit and a chopper circuit. The rectifier and inverter circuit inputs industrial frequency AC power and outputs controllable DC power, while the chopper circuit inputs controllable DC power and outputs pulse power. The inverter control circuit also includes an inverter control circuit, which inputs a voltage control signal and outputs a pulse width drive signal to the rectifier inverter circuit, controls the duty cycle of the pulse width drive signal according to the voltage control signal, and further controls the voltage and current of the controllable direct current; Its characteristics are: It also includes a voltage stabilization acquisition circuit, a soft start circuit and an input comparison circuit; The voltage stabilization acquisition circuit is used to: collect the voltage signal of the controllable direct current and output it to the input comparison circuit; The soft start circuit is used to: output a gradually changing reference voltage to the input comparison circuit according to the start signal; Input comparison circuit: outputs a gradually changing voltage control signal to the inverter control circuit according to the gradually changing reference voltage, thereby gradually increasing the duty cycle of the pulse width drive signal to achieve a soft start function.

2. The pulse power supply with soft start function according to claim 1, characterized in that: The soft start circuit includes a drive isolation circuit, a charge and discharge circuit and a follower regulation circuit; The driving isolation circuit is used to: obtain the start signal, and control the on and off of the transistor Q11 after driving and isolating; The charge and discharge circuit is used to charge and discharge the capacitor C903 according to the on-off change of the transistor Q11, and then output a gradually changing charge and discharge voltage to the follower regulation circuit; The follower regulation circuit is used to convert the gradually changing charge and discharge voltage into the gradually changing reference voltage, and adjust the threshold of the reference voltage by adjusting the adjustable resistor VR14.

3. The pulse power supply with soft start function according to claim 2, characterized in that: The drive isolation circuit mainly includes a transistor Q13 and an optocoupler U19. The positive electrode of the diode D903 inputs the start signal, the negative electrode of the diode D903 is connected to the base of the transistor Q13 in series with a resistor R911; the negative electrode of the diode D903 is connected to ground in series with a resistor R912, and the negative electrode of the diode D903 is connected to ground in series with a capacitor C904. The +12V power supply end is connected to the front end of the resistor R910, the back end of the resistor R910 is connected to the positive input end of the optocoupler U19, the negative input end of the optocoupler U19 is connected to the collector of the transistor Q13, and the emitter of the transistor Q13 is grounded; The positive output terminal of the optocoupler U19 is connected to the +12V power supply terminal, and the negative output terminal of the optocoupler U19 is connected in series with the resistor R909 and then connected to the base of the transistor Q11; The charging and discharging circuit mainly includes an operational amplifier U18 and a capacitor C903, a +12V power supply end connected to the front end of an adjustable resistor VR13, a rear end of the adjustable resistor VR13 connected in series with a resistor R906 and then grounded, a sliding end of the adjustable resistor VR13 connected in series with a resistor R907 connected to the reverse end of the operational amplifier U18, the same-direction end of the operational amplifier U18 is grounded, a capacitor C903 is connected in parallel between the reverse end and the output end of the operational amplifier U18, the reverse end of the operational amplifier U18 is connected to the front end of the resistor R908, the rear end of the resistor R908 is connected to the collector of the transistor Q11, and the emitter of the transistor Q11 is connected to the output end of the operational amplifier U18; The operational amplifier U18 is powered by +12V and -12V. When the transistor Q11 changes from the on state to the off state, the output voltage of the operational amplifier U18 gradually decreases to -12V. The following regulation circuit mainly includes a voltage stabilizing diode D902, an operational amplifier U15A, a transistor Q12, a resistor R903 and an adjustable resistor VR14; The output end of the operational amplifier U18 is connected to the front end of the resistor R916, the rear end of the resistor R916 is connected to the positive electrode of the voltage zener diode D902, and the negative electrode of the voltage zener diode D902 is grounded; The common terminal of the resistor R906 and the Zener diode D902 is connected to the inverting terminal of the operational amplifier U15A, the non-inverting terminal of the operational amplifier U15A is grounded, the output terminal of the operational amplifier U15A is connected to the front end of the resistor R901, the rear end of the resistor R901 is connected to the base of the transistor Q12, the emitter of the transistor Q12 is connected to the front end of the resistor R903, the rear end of the resistor R903 is connected to the inverting terminal of the operational amplifier U15A; the inverting terminal of the operational amplifier U15A is connected to the cathode of the diode D901; The collector of the transistor Q12 is connected to a +12V power supply terminal via a resistor R902, the emitter of the transistor Q12 is connected to the front end of an adjustable resistor VR14, the rear end of the adjustable resistor VR14 is grounded, and the sliding end of the adjustable resistor VR14 outputs the reference voltage; the emitter of the transistor Q12 is connected to a capacitor C902 via a resistor R905 via a resistor R905 connected to a ground; The output terminal of the operational amplifier U18 changes from 0V to -5V, the reverse terminal voltage of the operational amplifier U15A also changes from 0V to -5V, the emitter voltage of the transistor Q12 changes from 0V to 5V, and the voltage across the adjustable resistor VR14 also changes from 0V to 5V; When the output voltage of the operational amplifier U18 changes from -5V to -12V, due to the presence of the voltage stabilizing diode D902, the reverse terminal voltage of the operational amplifier U15A is always -5V, and the voltage across the adjustable resistor VR14 remains unchanged at 5V. By adjusting the sliding end of the adjustable resistor VR14, the threshold of the reference voltage can be adjusted.

4. The pulse power supply with soft start function according to claim 2, characterized in that: The input comparison circuit mainly includes an operational amplifier U5A; The reference voltage is input to the front end of the resistor R307, the rear end of the resistor R307 is connected to the front end of the resistor R308, the rear end of the resistor R308 is grounded, the common end of the resistor R307 and the resistor R308 is connected in series with the resistor R309 and then connected to the reverse end of the operational amplifier U5A, the non-inverting end of the operational amplifier U5A is connected to the output end of the voltage stabilization and acquisition circuit, the output end of the operational amplifier U5A is connected to the positive electrode of the diode D304, and the negative electrode of the diode D304 outputs the voltage control signal; The voltage stabilization acquisition circuit mainly includes an operational amplifier U9; The front end of the resistor R501 inputs the voltage signal of the controllable direct current, the rear end of the resistor R501 is connected to the front end of the adjustable resistor VR2, the rear end of the adjustable resistor VR2 is connected in series with a resistor R502 and then grounded, the sliding end of the adjustable resistor VR2 is connected to the front end of the resistor R503, the rear end of the resistor R503 is connected in series with a resistor R504 and then grounded, and the common end of the resistor R503 and the resistor R504 is connected in series with a resistor R506 and then connected to the same-direction end of the operational amplifier U9; The reverse end of the operational amplifier U9 is connected in series with a resistor R507 and then grounded; between the output end and the reverse end of the operational amplifier U9, a resistor R508 and a capacitor C503 are connected in parallel; the output end of the operational amplifier U9 is connected to the positive electrode of the diode R510, and the negative electrode of the diode R510 is connected to the positive end of the operational amplifier U5A; The two zero-adjustment bias terminals of the operational amplifier U9 are connected to the two ends of the adjustable resistor VR1. The sliding terminal of the adjustable resistor VR1 is connected in series with the resistor R509 and then connected to the -12V power supply terminal.

5. The pulse power supply with soft start function according to claim 1, characterized in that: The inverter control circuit includes a pulse width modulation circuit and a pulse width drive circuit; After the pulse width modulation circuit inputs the voltage control signal, it outputs a pulse width control signal; after the inverter drive circuit inputs the pulse width control signal, it outputs a pulse width drive signal; The pulse width modulation circuit is used to: control the duty cycle of the pulse width control signal according to the voltage control signal; The pulse width drive circuit is used to: isolate and improve the driving capability of the pulse width drive signal.

6. The pulse power supply with soft start function according to claim 5, characterized in that: The pulse width modulation circuit includes a pulse width modulation chip U4, and the model of the pulse width modulation chip U4 is SW494; The +V1 terminal of the pulse width modulation chip U4 is connected to a resistor R302 in series and then to ground. The +V2 terminal of the pulse width modulation chip U4 is connected to a resistor R301 in series and then to ground. The -V1 terminal and -V2 terminal of the pulse width modulation chip U4 are connected to a resistor R303 in series and then to ground. The voltage control signal is input to the +V1 terminal or the +V2 terminal of the pulse width modulation chip U4. The E1 and E2 terminals of the pulse width modulation chip U4 output two sets of pulse width control signals with complementary dead zones; The E1 terminal of the pulse width modulation chip U4 is connected to the anode of the diode D301, the E2 terminal of the pulse width modulation chip U4 is connected to the anode of the diode D302, the cathode of the diode D301 is connected to the cathode of the diode D302, the common terminal of the diode D301 and the diode D302 is connected in series with a resistor R313 and then grounded, the common terminal of the diode D301 and the diode D302 is connected to the first pin of the terminal group JP7, and the third pin of the terminal group JP7 is grounded; Short-circuit the first and third pins of terminal group JP7 to ground the E1 and E2 terminals of the pulse width modulation chip U4, forcing the duty cycle to zero.

7. The pulse power supply with soft start function according to claim 6, characterized in that: The -V1 and -V2 terminals of the pulse width modulation chip U4 are connected in series with capacitors C304 and then grounded; the +V1 terminal of the pulse width modulation chip U4 is connected in series with capacitors C303 and then grounded; the +V2 terminal of the pulse width modulation chip U4 is connected in series with capacitors C301 and then grounded; the +V2 terminal of the pulse width modulation chip U4 is connected in series with capacitors C302 and then grounded.

8. The pulse power supply with soft start function according to claim 5, characterized in that: The pulse width driving circuit includes an optical coupling isolation chip U1; The E1 terminal of the pulse width modulation chip U4 is connected to the front end of the resistor R103, the rear end of the resistor R103 is connected to the positive input terminal of the optocoupler isolation chip U1, and the negative input terminal of the optocoupler isolation chip U1 is grounded; The output end of the optocoupler isolation chip U1 is connected to the base of the NPN transistor Q1 and the PNP transistor Q2, the +20V power supply end is connected to the collector of the transistor Q1, the emitter of the transistor Q1 is connected to the emitter collector of the transistor Q2, and the collector of the transistor Q2 is grounded; the common end of the transistor Q1 and the transistor Q2 outputs the pulse width drive signal.

9. The pulse power supply with soft start function according to claim 8, characterized in that: The +20V power supply terminal is connected to the front end of the resistor R101, the rear end of the resistor R101 is connected in series with a reverse voltage zener diode D101 and then grounded, and the common end of the resistor R101 and the voltage zener diode D101 is connected to the second pin of the terminal group JP1; The common end of the transistor Q1 and the transistor Q2 is connected to the front end of the resistor R107, the rear end of the resistor R107 is connected to the front end of the resistor R108, and the rear end of the resistor R108 is connected to the second pin of the terminal group JP1; the common end of the resistor R107 and the resistor R108 is connected to the first pin of the terminal group JP1; A bidirectional voltage regulator diode DW1 is connected in series between the first and second pins of the terminal group JP1; When the transistor Q1 is turned on, a positive voltage is applied between the first pin and the second pin of the terminal group JP1; when the transistor Q2 is turned on, a negative voltage is applied between the first pin and the second pin of the terminal group JP1; The first pin and the second pin of the terminal group JP1 output a group of pulse width driving signals.

10. The pulse power supply with soft start function according to claim 9, characterized in that: The collector series capacitor C101 of the transistor Q1 is connected to the collector of the transistor Q2; the collector series capacitor C102 of the transistor Q1 is connected to the collector of the transistor Q2; the reverse voltage zener diode D101 is connected in parallel with the capacitor C103; the reverse voltage zener diode D101 is connected in parallel with the capacitor C104.

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