JP2009278747A - Power supply apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that on-duty of a chopper drive circuit driving a chopper circuit is restricted to 50% and the chopper drive circuit becomes a hindrance of a high speed operation of the chopper circuit since the chopper drive circuit uses a pulse transformer. <P>SOLUTION: A power supply apparatus includes the chopper circuit, an output control circuit controlling the chopper circuit, a chopper control circuit outputting a chopper control signal in synchronous to an output control signal and the chopper drive circuit driving the chopper circuit in accordance with the chopper control signal. The chopper control circuit generates a reference control signal having pulse width which is 1/2 of the output control signal, AND-operates the reference control signal and the output control signal, generates a first chopper control signal, AND-operates inversion of the reference control signal and generates a second chopper control signal. The chopper drive circuit drives a first pulse transformer forming the chopper circuit in accordance with the first output control signal and drives a second pulse transformer in accordance with the second output control signal. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a chopper drive circuit that drives a chopper circuit built in a power supply device.

  The chopper drive circuit that drives the chopper / switching element that forms the chopper circuit is usually used with a pulse transformer or with a photocoupler. When a pulse transformer is used, the on-duty is around 50%. When the photocoupler is used, on-duty is possible up to 100%, but the response speed is slow and it is difficult to increase the switching frequency of the chopper switching element.

  FIG. 5 is an electrical connection diagram of a conventional welding power source that performs (for example) soft switching. In the figure, the DC conversion circuit is formed of a rectifier circuit DR1 and a smoothing capacitor C1 provided in parallel on the output side.

  The chopper switching element TR1 is provided between the DC conversion circuit and the inverter circuit INV, opens and closes the DC voltage of the DC conversion circuit, and supplies power to the auxiliary capacitor C2.

  The inverter circuit INV forms a full bridge from opposing first to fourth switching elements (not shown), converts a DC voltage into a high-frequency AC voltage, and outputs it.

  The main transformer INT converts the high-frequency AC voltage converted by the inverter circuit INV into a high-frequency AC voltage suitable for arc machining, and the secondary rectifier circuit DR3 rectifies the output of the main transformer INT and passes through the DC reactor DCL. Then, electric power is supplied between the torch TH and the workpiece M.

  The output current detection circuit ID detects the output current on the secondary side of the main transformer INT and outputs it as an output current detection signal Id. The current corresponding output control circuit SCI performs PWM control that modulates the pulse width with a constant pulse frequency, and the first output control signal Sc1 and the second output control signal that are shifted from each other by a half cycle according to the output current detection signal Id. Controls the pulse width of Sc2.

  The inverter drive circuit IK drives the first switching element TR4 and the fourth switching element TR4, which are not shown, in synchronization with the first output control signal Sc1 being turned on, and the first output control signal Sc1 is turned off. The first inverter drive signal Ik1 for stopping the first switching element and the fourth switching element TR4 is output after a predetermined time elapses from the time point, and is not shown in synchronization with the ON of the second output control signal Sc2. The second switching element and the third switching element facing each other are driven, and the second switching element and the third switching element are stopped after a predetermined time has elapsed since the second output control signal Sc2 was turned off. 2 inverter drive signal Ik2 is output.

  The CD shown in FIG. 5 is a (prior art) chopper control circuit, and the chopper control circuit CD is synchronized with on / off of the first output control signal Sc1 and on / off of the second output control signal SC2. To output a chopper control signal Cd.

  6 is a detailed diagram of a conventional chopper drive circuit using a pulse transformer. The chopper drive circuit DC includes a primary drive switching element TR2 that is turned on in response to a chopper control signal Cd and the primary drive switching element TR2. A primary winding to which a voltage from a DC power supply is intermittently applied according to conduction of the drive switching element TR2 and an induced electromotive voltage according to a voltage applied to the primary winding are generated and output to the secondary winding. The secondary drive switching element 3 is turned on in accordance with the pulse transformer T1 and the induced electromotive voltage to drive the chopper switching element TR1.

FIG. 7 is a waveform timing chart for explaining the operation of the conventional power supply apparatus.
In FIG. 7, the waveform in FIG. 7A shows the first output control signal Sc1, the waveform in FIG. 7B shows the second output control signal Sc2, and the waveform in FIG. The waveform of FIG. 4D shows the second inverter drive signal Ik2, the waveform of FIG. 4E shows the first chopper control signal Cd, and the waveform of FIG. The waveform indicates the chopper drive signal Pd.

  When soft switching is performed to make the turn-off loss of the inverter circuit INV substantially zero, the chopper drive Dc shown in FIG. 7 (f) is turned off by the first inverter drive signal Ik1 shown in FIG. It is turned off a predetermined time before the second inverter drive signal Ik2 shown in FIG. At this time, the on-duty of the chopper drive Dc shown in FIG.

Next, the chopper drive circuit DC will be described when the on-duty of the chopper drive Dc is 50%.
When the positive voltage of the primary winding of the pulse transformer T1 shown in FIG. 6 is αV, for example, the negative voltage is determined by on-duty and can be obtained by the following equation:
From αV × (0.5 / 0.5), the negative voltage becomes αV, which is the same as the positive voltage.

However, when the on-duty of the chopper drive signal Dc shown in FIG. 7 (f) exceeds 50%, the negative voltage increases. For example, when the on-duty is 90%, the negative voltage is
αV × (0.9 / 0.1) = 9αV
And 9 times the positive voltage.
(For example, Patent Document 1)

JP 2001-345194 A

  The chopper circuit formed by the chopper / switching element shown in FIG. 5 is driven by the chopper driving circuit, opens and closes the DC voltage from the DC conversion circuit, and supplies it to the auxiliary capacitor and the inverter circuit. At this time, the on-duty of the chopper driving circuit is required to be close to 90% at the maximum, so the on-duty of the chopper driving circuit is controlled using a photocoupler that can be used even when the on-duty is 100%. However, there are few types of photocouplers that can perform high-speed switching in response to the demand for high-speed switching frequency of the chopper circuit, causing problems in stable supply and increasing costs.

  In order to increase the switching frequency of the chopper circuit, a chopper driving circuit using a pulse transformer shown in FIG. 6 is generally used. When the on-duty of the pulse transformer is 50% or less, the positive voltage of the primary winding of the pulse transformer is, for example, αV, the negative voltage is lower than αV, and a general pulse transformer can be used. When the on-duty of the pulse transformer is set to 90% in order to increase the switching frequency of the circuit, the negative voltage of the primary winding of the pulse transformer becomes 9αV, and the structure of the pulse transformer becomes complicated and large. End up.

  Accordingly, the present invention provides a chopper driving circuit that can increase the switching frequency of a chopper circuit using a general pulse transformer and can drive the chopper switching element even when the on-duty exceeds 50%. is there.

  In order to solve the above-described problem, the present invention includes a DC power supply circuit that rectifies a commercial AC power supply and outputs a DC voltage, and has a chopper switching element, and the chopper switching element is turned on and off according to the on / off state. A chopper circuit that converts a DC voltage into a predetermined DC voltage and supplies it to the load, an output control circuit that controls the pulse width of the output control signal based on the output voltage of the chopper circuit, and in synchronization with the output control signal In a power supply device comprising: a chopper control circuit that outputs a chopper control signal; and a chopper drive circuit that drives the chopper switching element in response to the chopper control signal, the chopper control circuit turns on the output control signal. A reference control signal having a pulse width of ½ of one period of the output control signal, and generating the reference control signal and the reference An AND logic with the force control signal to generate a first chopper control signal, an AND logic with the inverted signal of the reference control signal and the output control signal to generate a second chopper control signal, and the chopper drive The circuit conducts the first primary drive switching element in response to the first output control signal, and applies a predetermined voltage to the primary winding of the first pulse transformer by this conduction to conduct the secondary winding. An induced electromotive voltage is generated in the wire, and the second primary drive switching element is turned on in response to the second output control signal. With this conduction, a predetermined voltage is applied to the primary winding of the second pulse transformer. And an induced electromotive voltage is generated in the secondary winding, and the secondary induction of the first pulse transformer and the secondary winding of the second pulse transformer are OR-connected via a diode to thereby generate the two inductions. The chopper switch according to the electromotive voltage Driving the grayed element, a power supply device according to claim.

  According to a second aspect of the present invention, the pulse width of the reference control signal is set to 1/2 of the maximum pulse width of the output control signal.

  In the present invention, the configuration of the chopper drive circuit is the first primary drive switching element, and a predetermined voltage is applied to the primary winding according to the conduction of this element to generate an induced electromotive voltage in the secondary winding. A first pulse transformer to be output, a second primary drive switching element, a predetermined voltage is applied to the primary winding according to the conduction of the element, and an induced electromotive voltage is generated in the secondary winding and output. The second pulse transformer is provided in parallel, and the outputs of the first pulse transformer and the second pulse transformer are OR-connected via a diode, and the maximum of the first chopper control signal is obtained by the chopper control circuit. By limiting the pulse width to ½ of one cycle, the on-duty of the first pulse transformer of the chopper driving circuit becomes 50% at maximum and the on-duty of the second pulse transformer is also limited to 50% or less. . Therefore, a chopper driving circuit having an on-duty of about 100% can be easily realized without using a special pulse transformer having an on-duty of about 90%.

  In the second invention, when the maximum on-duty of the chopper driving circuit is, for example, 70%, the maximum on-duty of the first pulse transformer and the second pulse transformer becomes 35% and the configuration of the chopper driving circuit is the first. The maximum voltages applied to the drain and source of the primary drive switching element and the second primary drive switching element become uniform, leading to an improvement in the reliability of the two switching elements.

  FIG. 1 is an electrical connection diagram of a power supply device according to an embodiment of the present invention, for example, a power supply device using a step-down chopper circuit. In the figure, components having the same reference numerals as those in the electrical connection diagram of the conventional power supply apparatus shown in FIG. 5 and a welding power source (for example) performing soft switching perform the same operation, and thus the description thereof will be omitted, and the components having different reference numerals will be described. Only the thing is explained. In the embodiment of the present invention, the step-down chopper circuit is described. However, the present invention can also be applied to a step-up chopper circuit.

  The DC power supply circuit is formed of a rectifier circuit DR1 and a first smoothing capacitor C1 provided in parallel on the output side, and rectifies a commercial AC power supply to output a DC voltage.

  The step-down chopper circuit is formed by the chopper / switching element TR1, the freewheeling diode DR2, the DC reactor DCL and the second smoothing capacitor C3 shown in FIG. 1, and the direct current from the DC power supply circuit is based on the on-duty of the chopper / switching element TR1. The voltage is stepped down and supplied to the load.

  The output voltage detection circuit VD detects the output voltage of the step-down chopper circuit and outputs it as an output voltage detection signal Vd. The output control circuit SC performs PWM control that modulates the pulse width with a constant pulse frequency, and controls the pulse width of the output control signal Sc based on the value of the output voltage detection signal Vd.

FIG. 3 is a detailed diagram of the chopper control circuit CO of the present invention.
In the figure, the chopper control circuit CO is formed by a monostable multivibrator circuit TM, an inverting circuit IN, a first AND circuit AND1, and a second AND circuit AND2. The monostable multivibrator circuit TM The reference control signal Tm having a pulse width that is ½ of one cycle of the output control signal Sc is generated and output in synchronization with the turning on. The first AND circuit AND1 performs an AND logic on the output control signal Sc and the reference control signal Tm and outputs the result as the first chopper control signal Co1, and the second AND circuit AND2 outputs the first output control signal Sc. And the inverted signal In of the reference control signal Tm are performed and output as the second chopper control signal Co2.
Further, the pulse width of the reference control signal Tm may be ½ of the maximum pulse width of the output control signal Sc.

FIG. 2 is a detailed diagram of the chopper drive circuit PD of the present invention.
As shown in the figure, the first primary drive switching element TR3 which is turned on / off according to the first chopper control signal Co1 and the conduction / cutoff of the first primary drive switching element TR3 are illustrated. A first pulse transformer T1 that generates an induced electromotive voltage according to a voltage applied to the primary winding and the primary winding intermittently applied with a voltage from an omitted DC power supply and outputs the induced voltage to the secondary winding; The second primary drive switching element TR5 that conducts / cuts off according to the second chopper control signal Co2 and the voltage from the DC power supply intermittently according to the conduction / cutoff of the second primary drive switching element TR5 Second pulse transformer T2 that generates an induced electromotive voltage in accordance with the primary winding to be applied and the voltage applied to the primary winding and outputs it to the secondary winding, the first pulse transformer T1, 2 pulse transformer T OR-connected to the secondary drive switching element TR4 via the diode output and, it is formed by the secondary drive switching element for high side operation in accordance with two inductive electromotive voltage.

FIG. 4 is a waveform timing chart for explaining the operation of the embodiment of the present invention.
4, the waveform of FIG. 4A shows the output control signal Sc, the waveform of FIG. 4B shows the reference control signal Tm, the waveform of FIG. 4C shows the inverted signal In, and FIG. The waveform in (d) shows the first chopper control signal Co1, the waveform in (e) shows the second chopper control signal Co2, and the waveform in (f) shows the chopper drive signal Pd.

Next, the operation of the present invention will be described with reference to the waveform timing chart of FIG.
When the start signal Ts is output from the start switch TS shown in FIG. 1, the output control circuit SC compares the predetermined voltage reference value Vr and the value of the output voltage detection signal Vd (for example, Vr−Vd). ) To control the pulse width of the output control signal Sc shown in FIG.

  At time t = t1, when the output control signal Sc shown in FIG. 4A is input to the monostable multivibrator circuit TM of the chopper control circuit CO shown in FIG. 3 and becomes high level, the monostable multivibrator circuit TM is In synchronization with the output control signal Sc being turned on, the reference control signal Tm shown in FIG. 5B having a pulse width of ½ of one cycle of the output control signal Sc is output. Further, the pulse width of the reference control signal Tm may be ½ of the maximum pulse width of the output control signal Sc.

  At time t = t1, the first AND circuit AND1 performs AND logic on the output control signal Sc and the reference control signal Tm, and sets the first chopper control signal Co1 shown in FIG. 4D to High level. Further, the second AND circuit AND2 performs AND logic on the output control signal Sc and the inverted signal In of the reference control signal Tm, and sets the second chopper control signal Co2 shown in FIG.

  The chopper drive circuit PD performs an OR logic on the first chopper control signal Co1 and the second chopper control signal Co2 to set the chopper drive signal Pd shown in FIG. 4 (f) to the high level, and at time t = t1 The chopper switching element TR1 is conducted.

  At time t = t1 to t2, the first chopper control signal Co1 shown in FIG. 4D maintains the high level, so that the conduction of the chopper switching element TR1 continues.

  In the monostable multivibrator circuit TM, the reference control signal Tm becomes the low level at time t = t2 when a time of ½ cycle elapses from the high level of the output control signal Sc.

  At time t = t2, the first AND circuit AND1 performs AND logic on the output control signal Sc and the reference control signal Tm, and sets the first chopper control signal Co1 shown in FIG. 4D to the Low level. Further, the second AND circuit AND2 performs an AND logic between the high level of the output control signal Sc and the high level of the inverted signal In of the reference control signal Tm, and outputs the second chopper control signal Co2 shown in FIG. Set to High level.

  The chopper drive circuit PD performs an OR logic between the first chopper control signal Co1 and the second chopper control signal Co2 to maintain the high level of the chopper drive signal Pd shown in FIG. Continue conducting TR1.

  At time t = t3 shown in FIG. 4, when the output control signal Sc shown in FIG. 4 (a) becomes the low level, the second chopper control signal Co2 shown in FIG. 4 (e) changes from the high level to the low level. The drive circuit PD performs an OR logic between the first chopper control signal Co1 and the second chopper control signal Co2, and the chopper drive signal Pd shown in FIG. 4 (f) becomes Low level, and the chopper switching element TR1 is turned on. Cut off. The chopper / switching element TR1 continues to be cut off during the period from time t = t3 to t4.

  At time t = t4, when the output control signal Sc shown in FIG. 4A again becomes a high level, the monostable multivibrator circuit TM is synchronized with the output control signal Sc being turned on, and the output control signal Sc is in one cycle. A reference control signal Tm having a pulse width of 1/2 is output.

  At time t = t4, the first AND circuit AND1 performs AND logic on the output control signal Sc and the reference control signal Tm, and sets the first chopper control signal Co1 shown in FIG. 4D to High level. Further, the second AND circuit AND2 performs an AND logic of the first output control signal Sc1 and the inverted signal In of the reference control signal Tm, and sets the second chopper control signal Co2 shown in FIG. To do.

  The chopper drive circuit PD performs an OR logic on the first chopper control signal Co1 and the second chopper control signal Co2 to set the chopper drive signal Pd shown in FIG. 4 (f) to the high level, and at time t = t4 The chopper switching element TR1 is conducted. Thereafter, the same operation as described above is repeated, and the description thereof is omitted.

  In the step-down chopper circuit described above, the DC voltage supplied from the DC power supply circuit is stepped down and supplied to the load based on the on-duty of the chopper drive signal Pd shown in FIG. In the chopper circuit of the present invention, the operation is described using the step-down chopper circuit. However, the step-up chopper circuit is used to boost the DC voltage supplied from the DC power supply circuit based on the on-duty of the chopper drive signal Pd. However, it may be supplied to a load.

  In the present invention, two pulse transformers are provided in parallel as the configuration of the chopper driving circuit for driving the chopper / switching element, and two pulse transformers are provided based on the first output control signal and the second output control signal of the output control circuit. By suppressing the on-duty to 50% or less, a normal pulse transformer can be used, and a chopper driving circuit having an on-duty in the vicinity of 100% can be realized.

It is a connection diagram of a power supply device according to an embodiment of the present invention. It is a detailed view of a chopper drive circuit of the present invention. It is a detailed view of the chopper control circuit of the present invention. It is a waveform timing diagram for demonstrating operation | movement of the power supply device of this invention. It is a connection diagram of the power supply device of a prior art. It is a detailed view of a conventional chopper drive circuit. It is a waveform timing diagram for demonstrating operation | movement of the conventional power supply device.

Explanation of symbols

AND1 first AND circuit AND2 second AND circuit C1 smoothing capacitor C2 auxiliary capacitor CD (conventional) chopper control circuit Cd (conventional) chopper control signal CO (invention) chopper control circuit Co1 (invention) 1 chopper control signal Co2 (second invention) chopper control signal DC (conventional) chopper drive circuit Dc (conventional) chopper drive signal DR1 primary rectifier circuit DR2 freewheeling diode DR3 secondary rectifier circuit DCL DC reactor ID Output current detection circuit Id Output current detection signal IK Inverter drive circuit Ik1 First inverter drive signal Ik2 Second inverter drive signal IR Current reference setting circuit Ir Current reference value IN Inversion circuit INT Main transformer INV Inverter circuit M Workpiece PD (invention) chopper drive Circuit Pd (of the present invention) chopper drive signal SC output control circuit Sc output control signal Sc1 first output control signal Sc2 second output control signal T1 first pulse transformer T2 second pulse transformer TH torch TM monostable Multivibrator circuit TS Start switch Ts Start signal TR1 Chopper switching element TR2 First primary drive switching element TR3 Secondary drive switching element TR4 Second primary drive switching element VD Output voltage detection circuit Vd Output voltage detection signal VR Voltage Reference setting circuit Vr Voltage reference value

Claims (2)

A DC power supply circuit that rectifies commercial AC power supply and outputs a DC voltage, and has a chopper switching element, and converts the DC voltage into a predetermined DC voltage according to the on / off state of the chopper switching element. A chopper circuit to be supplied; an output control circuit that controls a pulse width of an output control signal based on an output voltage of the chopper circuit; a chopper control circuit that outputs a chopper control signal in synchronization with the output control signal; and the chopper And a chopper driving circuit that drives the chopper switching element in accordance with a control signal. The chopper control circuit is synchronized with the output control signal being turned on, and is 1 / of one cycle of the output control signal. Generating a reference control signal having a pulse width of 2, and performing an AND logic on the reference control signal and the output control signal. A chopper control signal is generated, and an AND logic of the inverted signal of the reference control signal and the output control signal is performed to generate a second chopper control signal, and the chopper drive circuit responds to the first output control signal The first primary drive switching element is turned on, a predetermined voltage is applied to the primary winding of the first pulse transformer by this conduction to generate an induced electromotive voltage in the secondary winding, and the second In response to the output control signal, the second primary drive switching element is turned on, and by this conduction, a predetermined voltage is applied to the primary winding of the second pulse transformer, and an induced electromotive voltage is applied to the secondary winding. The secondary winding of the first pulse transformer and the secondary winding of the second pulse transformer are OR-connected via a diode to drive the chopper switching element according to the two induced electromotive voltages. A power supply characterized by Location. 2. The power supply device according to claim 1, wherein a pulse width of the reference control signal is set to ½ of a maximum pulse width of the output control signal.

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