CN209930164U - AC-DC conversion circuit - Google Patents
AC-DC conversion circuit Download PDFInfo
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- CN209930164U CN209930164U CN201920904649.4U CN201920904649U CN209930164U CN 209930164 U CN209930164 U CN 209930164U CN 201920904649 U CN201920904649 U CN 201920904649U CN 209930164 U CN209930164 U CN 209930164U
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Abstract
According to the embodiment of the present invention, an ac-dc conversion circuit is disclosed, wherein the ac-dc conversion circuit controls the on and off states of the thyristor switch according to the value of the ac input voltage, and when the ac input voltage is within a first voltage range, the control circuit controls the thyristor switch to be on to increase the dc output voltage; when the alternating current input voltage is in the second voltage range, the control circuit controls the silicon controlled switch to be turned off all the time or the first capacitor or the second capacitor is short-circuited, and the control circuit controls the silicon controlled switch to be turned on, so that the direct current output voltage of the alternating current input voltage in the first voltage range is close to the value of the direct current output voltage of the alternating current input voltage in the second voltage range. The utility model discloses during the alternating current input voltage of different numerical values, reduced alternating current-direct current converting circuit's direct current output voltage's fluctuation.
Description
Technical Field
The utility model relates to a power electronics field, more specifically say, relate to an exchange-direct current converting circuit.
Background
With the wide popularization and use of mobile phones and computers, the application of chargers is more and more extensive. In application of a PD or QC charger, to convert alternating current into direct current to charge a load, the input voltage of the charger needs to be suitable for 100-240V alternating current power input. In the prior art, an ordinary rectifier bridge is directly utilized to convert alternating current into direct current, and the rectifier bridge receives 100-240V alternating current. When the common rectifier bridge directly converts 100-240V alternating current into direct current, the range of the alternating current input voltage is large, so that the corresponding range of the direct current output voltage is large, the optimization of a rear-stage power device of a charger is not facilitated, the size of the charger is large, the requirement of the market for the large power and small size of the charger is more and more obvious, if the input voltage range of a direct current-direct current conversion circuit is small, power devices such as a rear-stage power tube and a transformer can be optimized, and the size of the charger is reduced.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a novel ac-dc converting circuit reduces dc-dc converting circuit's input voltage scope, has solved the ac-dc converting circuit's among the prior art dc output voltage scope great, is unfavorable for the optimization of back level power device, causes the technical problem such as the volume of charger is great.
The embodiment of the utility model provides an exchange-direct current converting circuit, include:
the rectifier circuit comprises a first input end, a second input end, a first output end and a second output end, wherein the first input end and the second input end are used for receiving alternating-current input voltage;
the first capacitor and the second capacitor are connected in series between the first output end and the second output end of the rectifying circuit;
a thyristor switch coupled between one of the first and second input terminals and a common terminal of the first and second capacitors;
and the control circuit controls the on-off state of the silicon controlled switch according to the value of the alternating current input voltage so as to reduce the fluctuation of the direct current output voltage of the alternating current-direct current conversion circuit when the alternating current input voltage has different values.
Preferably, when the ac input voltage is in a first voltage range, the control circuit controls the thyristor switch to be turned on to increase the dc output voltage.
Preferably, when the alternating current input voltage is in a second voltage range, the control circuit controls the silicon controlled switch to be always turned off.
Preferably, when the alternating current input voltage is in a second voltage range, the first capacitor or the second capacitor is short-circuited, and the control circuit controls the silicon controlled switch to be switched on.
Preferably, one of the first capacitor and the second capacitor is connected with a diode in parallel.
Preferably, the control circuit controls the drive thyristor switch to be conducted for no more than 1 time in both positive and negative half periods of the alternating input voltage.
Preferably, the thyristor switch is driven to conduct when the absolute value of the difference of the signals representing the voltages across the thyristor switch is greater than a corresponding threshold.
Preferably, the thyristor switch is driven to conduct when the difference between the signal representative of the ac input voltage and a first voltage, which is the smaller of the signal representative of the first capacitor voltage and the signal representative of the second capacitor voltage, is greater than a corresponding threshold value.
Preferably, the control circuit detects voltages at two ends of the silicon controlled switch, and drives the silicon controlled switch to be switched on when an absolute value of a difference value of the voltages at the two ends of the silicon controlled switch is greater than a first threshold value.
Preferably, the control circuit detects a voltage division signal of the voltage at the two ends of the silicon controlled switch, and drives the silicon controlled switch to be switched on when an absolute value of a difference value of the voltage division signal of the voltage at the two ends of the silicon controlled switch is greater than a third threshold value.
Preferably, the detected voltage of one end of the silicon controlled switch and the first threshold are respectively superposed with a first signal, and when the absolute value of the difference value of the voltages at the two ends of the silicon controlled switch after the superposition of the first signal is greater than the value of the superposition of the first threshold and the first signal, the silicon controlled switch is driven to be switched on.
Preferably, the control circuit detects an input voltage, a voltage of the first capacitor, and a voltage of the second capacitor, and drives the thyristor switch to be turned on when a difference between the input voltage and the first voltage is greater than a second threshold, where the first voltage is a smaller value of the first capacitor voltage and the second capacitor voltage.
Preferably, the control circuit detects a voltage division signal of the input voltage, a voltage division signal of the first capacitor voltage, and a voltage division signal of the second capacitor voltage, and drives the thyristor switch to be turned on when a difference value between the voltage division signal of the input voltage and the second voltage is greater than a fourth threshold value, where the second voltage is a smaller value of the voltage division signal of the first capacitor voltage and the voltage division signal of the second capacitor voltage.
Preferably, the control circuit adjusts the conduction time of the thyristor switch to reduce the duration of the holding current of the thyristor switch.
Preferably, the control circuit adjusts the on-time of the thyristor switch, so that after the thyristor is turned on, the charging current flowing through the first output end and the second output end is greater than the holding current of the thyristor switch.
Compared with the prior art, the technical scheme of the utility model have following advantage: the AC-DC conversion circuit of the utility model controls the on-off state of the silicon controlled switch according to the value of the AC input voltage, when the AC input voltage is in a first voltage range, the control circuit controls the silicon controlled switch to be on so as to increase the DC output voltage; when the alternating current input voltage is in the second voltage range, the control circuit controls the silicon controlled switch to be turned off all the time, the first capacitor or the second capacitor is short-circuited, the control circuit controls the silicon controlled switch to be turned on, and the direct current output voltage is unchanged, so that the direct current output voltage of the alternating current input voltage in the first voltage range is close to the value of the direct current output voltage of the alternating current input voltage in the second voltage range. The utility model discloses to the great alternating current input voltage of numerical range change, control direct current output voltage's scope has reduced in less interval when the alternating current input voltage of different numerical values alternating current-direct current converting circuit's direct current output voltage's fluctuation. In addition, the control circuit also controls the drive of the silicon controlled switch, so that the times of driving the silicon controlled switch are not more than 1 in the positive half period and the negative half period of the alternating current input voltage, the power loss is reduced, and the EMI performance is better.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent from the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:
fig. 1 is a circuit diagram of an embodiment of an ac-dc conversion circuit according to the present invention;
fig. 2 is a schematic block diagram of the control circuit of the present invention;
fig. 3 is a schematic circuit diagram of a first embodiment of the control circuit of the present invention;
fig. 4 is a schematic circuit diagram of a second embodiment of the control circuit of the present invention;
fig. 5 is a waveform diagram of the second embodiment of the control circuit of the present invention;
fig. 6 is a schematic circuit diagram of a third embodiment of the control circuit of the present invention.
Detailed Description
The present invention will be described below based on examples, but the present invention is not limited to only these examples. In the following detailed description of the present invention, certain specific details are set forth in detail. It will be apparent to those skilled in the art that the present invention may be practiced without these specific details. Well-known methods, procedures, components and circuits have not been described in detail so as not to obscure the present invention.
Further, those of ordinary skill in the art will appreciate that the drawings provided herein are for illustrative purposes and are not necessarily drawn to scale.
Meanwhile, it should be understood that, in the following description, a "circuit" refers to a conductive loop constituted by at least one element or sub-circuit through electrical or electromagnetic connection. When an element or circuit is referred to as being "connected to" another element or element/circuit is referred to as being "connected between" two nodes, it may be directly coupled or connected to the other element or intervening elements may be present, and the connection between the elements may be physical, logical, or a combination thereof. In contrast, when an element is referred to as being "directly coupled" or "directly connected" to another element, it is intended that there are no intervening elements present.
Fig. 1 is a schematic circuit diagram of an embodiment of the ac-dc conversion circuit of the present invention, which includes a rectifier circuit, a first capacitor C1, a second capacitor C2, and a thyristor Q1, wherein the rectifier circuit includes a first input terminal L, a second input terminal N, a first output terminal, and a second output terminal, and the first input terminal L and the second input terminal N are used for receiving an ac input voltage Vin; the first capacitor C1 and the second capacitor C2 are connected in series between the first output end and the second output end of the rectifying circuit; the thyristor switch Q1 is coupled between one of the first input terminal L and the second input terminal N and a common terminal SW of the first capacitor C1 and the second capacitor C2; the control circuit controls the on and off states of the silicon controlled switch Q1 according to the value of the alternating current input voltage Vin, so that the fluctuation of the direct current output voltage Vout of the alternating current-direct current conversion circuit is reduced when the alternating current input voltage Vin has different values. Wherein the sum of the voltages of the first capacitor C1 and the second capacitor C2 is the DC output voltage Vout.
According to alternating current-direct current converting circuit, when the alternating current input voltage of different numerical values, through control silicon controlled switch's the on and off state, switch mode to reach the undulant mesh that reduces the direct current output voltage of output, for example, can be for keeping mode such as invariable basically, perhaps direct current output voltage's variation range is at 20% within range. When the value of the alternating current input voltage is lower, the value of the direct current output voltage can be increased to be close to the value of the direct current output voltage when the value of the alternating current input voltage is higher through a boosting-like working mode. By this implementation, the size of a filter circuit, such as a filter capacitor, in an ac-dc conversion circuit is reduced. Furthermore, when the direct-current output voltage is used as a power supply voltage to provide power supply for a subsequent circuit, the withstand voltage range of components in the subsequent circuit can be further set to be smaller, for example, when the subsequent circuit is a direct-current-direct-current converter, the power transistor can be selected to have lower withstand voltage requirement, and the selection and the manufacturing process of the power transistor are facilitated; furthermore, the voltage withstanding requirement of inductive elements such as transformers is reduced correspondingly, the size is reduced, the process requirement is greatly reduced, the manufacturing cost is greatly reduced, and the stability of the system is also improved. Furthermore, what exchange-direct current converting circuit directly utilized is silicon controlled rectifier switch, control is simple, and only need drive once just can maintain and switch on by load current, need not to drive just can switch on if the triode always to lower than the pressure drop and the cost of MOS pipe, have obvious advantage, be particularly suitable for power frequency cycle's switch. In addition, the connected mode of silicon controlled switch here is not limited, silicon controlled switch's control end can be close to the one end of two electric capacity, also can be close to rectifier circuit's one end, the utility model discloses do not restrict to this.
When alternating current input voltage is in first voltage range, control circuit control silicon controlled rectifier switch switches on, exchange-direct current converting circuit work in voltage doubling rectification mode, in order to increase direct current output voltage, one of them implementation mode, work as alternating current input voltage is when second voltage range, control circuit control silicon controlled rectifier switch turns off all the time, exchange-direct current converting circuit work is in bridge rectifier mode for alternating current input voltage is when first voltage range direct current output voltage is close when alternating current input voltage is in the second voltage range direct current output voltage's numerical value, the second voltage range is greater than first voltage range, and second voltage range and first voltage range can not have the cross, also can have the cross, the utility model discloses do not restrict to this. For example, the first voltage range is 90V-180V, the second voltage range is 160-360V, or the second voltage range is 190V-360V. Specifically, when the ac-dc conversion circuit operates in the voltage-doubling rectification mode, the ac input voltage Vin charges the first capacitor C1 and the second capacitor C2 in positive and negative half cycles, respectively, so that the value of the dc output voltage in this mode is 2 times that of the dc output voltage in the bridge rectification mode, thereby increasing the value of the dc output voltage when the ac input voltage is in the first range, and further reducing the fluctuation of the dc output voltage.
Optionally, when the ac input voltage is within the second voltage range, the first capacitor or the second capacitor is short-circuited, the control circuit controls the thyristor switch to be turned on, and the ac-dc conversion circuit operates in a half-voltage-doubling rectification mode. Specifically, when the ac-dc conversion circuit works in the voltage-doubling rectification mode, the ac input voltage Vin charges the first capacitor C1 and the second capacitor C2 in positive and negative half periods, respectively, and when the ac-dc conversion circuit works in the half voltage-doubling rectification mode, the first capacitor or the second capacitor is short-circuited, so that the ac input voltage Vin charges the first capacitor or the second capacitor in only one period in the positive and negative half periods, and thus the value of the dc output voltage in the voltage-doubling rectification mode is 2 times that of the dc output voltage in the half voltage-doubling rectification mode, thereby reducing the fluctuation of the dc output voltage.
Optionally, a diode may be connected in parallel to the first capacitor or the second capacitor for short-circuiting the first capacitor or the second capacitor. For example, a series structure formed by connecting a diode and a first switch in series is connected in parallel to the second capacitor, and the cathode of the diode is a common terminal SW of the first capacitor and the second capacitor or a common terminal of the first switch and the diode. When the alternating current input voltage is in a first voltage range, the first switch is opened, the alternating current input voltage Vin charges the first capacitor C1 and the second capacitor C2 in positive and negative half periods respectively, the alternating current-direct current conversion circuit works in a voltage-doubling rectification mode, when the alternating current input voltage is in a second voltage range, the first switch is closed, the second capacitor is short-circuited, the alternating current input voltage Vin charges the first capacitor C1 only in the positive half period, and the alternating current-direct current conversion circuit works in the half voltage-doubling rectification mode.
The control circuit adjusts the conduction time of the silicon controlled switch so as to reduce the duration time of the holding current of the silicon controlled switch. The control circuit adjusts the conduction time of the silicon controlled switch, so that after the silicon controlled switch is conducted, the charging current flowing through the first output end and the second output end is larger than the maintaining current of the silicon controlled switch.
Optionally, the rectifier circuit is a full-bridge rectifier circuit, including first diode D1, second diode D2, third diode D3 and fourth diode D4, the negative poles of first diode D1 and second diode D2 are all connected the first output end, the positive pole of first diode D1 is connected the first input end, second diode D2 positive pole is connected the second input end, the positive poles of third diode D3 and fourth diode D4 are all connected the second output end, the negative pole of third diode D3 is connected the first input end, the negative pole of fourth diode D4 is connected the second input end. The diode can be replaced by a device with a switching function, such as a triode, a MOS tube and the like. The utility model discloses do not restrict this.
Optionally, in an implementation manner, the ac-dc conversion circuit further includes a voltage detection module, which directly or indirectly obtains information of a magnitude of the ac input voltage, for example, the voltage detection module directly receives ac input voltages Vin with different magnitudes, outputs a first signal representing an ac input voltage range, and the control circuit controls the on and off of the thyristor switch according to the first signal, so as to adjust a working mode of the ac-dc conversion circuit.
And when the voltage-multiplying rectification mode and the half voltage-multiplying rectification mode are adopted, the control circuit controls the conduction of the silicon controlled switch, the conduction of the silicon controlled switch needs to be driven, and therefore the control circuit also needs to control the driving of the silicon controlled switch.
The utility model discloses a silicon controlled switch drive mode does in the positive and negative half period of alternating current input voltage, control circuit control drive silicon controlled switch's number of times all is not greater than 1 time. The control circuit directly or indirectly detects the related voltage, obtains voltage signals representing the voltages at the two ends of the silicon controlled switch through the related voltage, and drives the silicon controlled switch to be conducted when the difference value of the voltage signals representing the voltages at the two ends of the silicon controlled switch is larger than the corresponding threshold value.
The corresponding threshold value can be set according to the specific voltage signal which is used for representing the voltage across the silicon controlled switch. The threshold value can be 0, namely when the difference value of the voltage signals representing the voltages at the two ends of the silicon controlled switch is greater than 0, the silicon controlled switch is driven to be conducted. The corresponding threshold may also be a constant greater than zero, which is not limited herein. In addition, the difference value comprises the difference between the signal representing the voltage of the second end of the silicon controlled switch and the signal representing the voltage of the first end, and the difference between the signal representing the voltage of the first end of the silicon controlled switch and the signal representing the voltage of the first end, and when one of the signal representing the voltage of the first end of the silicon controlled switch and the signal representing the voltage of the first end meets the requirement that the voltage of the second end is larger than the corresponding threshold value.
And further, when the absolute value of the difference value of the signals representing the voltages at the two ends of the silicon controlled switch is greater than the corresponding threshold value, the silicon controlled switch is driven to be conducted. Optionally, when a difference between the signal representing the ac input voltage and a first voltage is greater than a corresponding threshold, the thyristor switch is driven to be turned on, where the first voltage is a smaller value of the signal representing the first capacitor voltage and the signal representing the second capacitor voltage.
The utility model discloses a silicon controlled switch drive mode is for starting from alternating current input voltage zero crossing, sends a drive current pulse every fixed time to ensure that silicon controlled switch switches on. Because the scheme sends out the driving current pulse for many times in a half period and still sends out the driving current pulse even if the silicon controlled switch is conducted, the loss is large, and the silicon controlled switch is not suitable for a standby working state; the problems that the conduction point is not fixed, the conduction point shakes and the like exist, so that the current can have large di/dt when the silicon controlled switch is conducted, and the EMI performance is influenced. And the utility model discloses the defect of second kind of silicon controlled switch drive mode can be overcome to first silicon controlled switch drive mode, with the positive and negative half within-period of alternating current input voltage, the drive number of times reduces to and all is not greater than 1, has reduced loss and stand-by power consumption, di/dt when having reduced silicon controlled switch and switching on, can be applied to in the higher charger of consumption requirement. Therefore, the utility model discloses carry out detailed explanation to a silicon controlled switch drive mode.
Fig. 2 is a schematic diagram of a control circuit of a second driving mode of the thyristor switch according to the present invention; the control circuit comprises a voltage detection circuit, a comparison circuit and a driving circuit, the voltage detection circuit directly or indirectly obtains the information of the numerical value of the voltage at two ends of the controllable silicon, the comparison circuit compares the information of the numerical value of the voltage at two ends of the controllable silicon directly or indirectly, and when the difference value of the information of the numerical value of the voltage at two ends of the controllable silicon directly or indirectly is larger than the corresponding threshold value, the driving circuit drives the controllable silicon to be conducted. The way of driving the thyristors here may be current driven or voltage driven, and the present invention is not limited thereto. The driving circuit injects or extracts current between the controlled silicon control end and the second end to drive controllable conduction. When the silicon controlled rectifier is conducted, the current of the capacitor charged by the alternating-current input voltage meets the maintaining current of the silicon controlled rectifier, and the driving current can be withdrawn so as to reduce the loss. Specifically, the voltage detection circuit detects the relevant voltage, obtains voltage signals representing voltages at two ends of the silicon controlled switch through the relevant voltage, and drives the silicon controlled switch to be conducted when the difference value of the voltage signals representing the voltages at the two ends of the silicon controlled switch is larger than the corresponding threshold value.
The utility model discloses give the embodiment respectively to direct and indirect detection silicon controlled rectifier both ends voltage. Directly detecting the voltage at two ends of the controlled silicon, namely detecting the voltage at two ends of the controlled silicon or the voltage division of the voltage at two ends of the controlled silicon; and indirectly detecting the voltage at two ends of the controlled silicon, namely detecting the alternating current input voltage, the first capacitor voltage and the second capacitor voltage or detecting the divided voltage of the alternating current input voltage, the divided voltage of the first capacitor voltage and the divided voltage of the second capacitor voltage. It should be noted that, here, it is also possible to detect multiples of each voltage, but in practice, it is general to detect the divided voltage, and the present invention is not limited thereto. Specifically, when the absolute value of the difference value of the signals representing the voltages at the two ends of the silicon controlled switch is greater than the corresponding threshold value, the silicon controlled switch is driven to be conducted. And when the difference value between the signal representing the alternating current input voltage and the first voltage is larger than the corresponding threshold value, the silicon controlled switch is driven to be conducted, wherein the first voltage is the smaller value of the signal representing the first capacitor voltage and the signal representing the second capacitor voltage.
Fig. 3 is a schematic circuit diagram of a first embodiment of the control circuit of the present invention; the voltage detection circuit directly detects the voltage V of the first end of the controlled silicon Q1MT1And a voltage V at the second terminalMT2The comparison circuit comprises two comparators, and when the voltage V at the second end of the silicon controlled switchMT2And a first terminal voltage VMT1Is greater than a first threshold value Vth1Or less than a negative first threshold value, i.e. -Vth1When the absolute value of the difference value of the voltages at the two ends of the silicon controlled switch is larger than the first threshold value, the driving circuit sends driving current to the control end of the silicon controlled switch to drive the silicon controlled switch to be conducted. Here the control end of silicon controlled rectifier is close to two electric capacity ends, also can be close to alternating current input voltage end in other embodiments, the silicon controlled rectifier be current drive, in other embodiments, also can be voltage drive, and the driving current of silicon controlled rectifier can be for just, also can be for the burden, the utility model discloses to this all not restriction.
Fig. 4 is a schematic circuit diagram of a second embodiment of the control circuit of the present invention; wherein the voltage detection still directly detects the voltage V at the first end of the controlled silicon Q1MT1And a voltage V at the second terminalMT2In comparison, the voltage V at the second terminal is limited by some devices considered, such as a comparator, to the negative input valueMT2And a first threshold value Vth1And a negative first threshold value-Vth1Superimposed with a voltage signal VCMAnd obtaining a second terminal voltage VMT2Superimposed voltage signal VCMThen and the first terminal voltage VMT1A difference of (i.e. V)MT2+VCM-VMT1When the difference is greater than a first threshold value Vth1Sum voltage signal VCMSum of (i) VCM+Vth1Or less than the negative first threshold-sum voltage signal VCMSum of (i) VCM-Vth1And when the driving circuit is used, the driving circuit sends out driving current to the control end of the silicon controlled rectifier to drive the silicon controlled rectifier switch to be conducted.
Specifically, the comparison circuit comprises an operational amplifier A1, a first comparison circuit U1 and a second comparison circuit U2, wherein a first input end of the operational amplifier A1 receives a second end voltage VMT2And a first voltage VCMThe second receiving end of the operational amplifier A1 receives the first terminal voltage VMT1The second input terminal of the operational amplifier A1 is connected to the output terminal of the operational amplifier A1 through a resistor, and the output V of the operational amplifier A1SENTo the negative terminal of the first comparator U1 and to the positive terminal of the second comparator U2, the positive terminal of the first comparator U1 receives VCM-Vth1The negative end of the second comparator U2 receives VCM+Vth1The outputs of the first comparator U1 and the second comparator U2 are connected to the driving circuit through an OR gate. The drive circuit comprises a first capacitor VCC and a switch K1, the first capacitor is connected between the second end of the thyristor and the ground, one end of the switch K1 is connected with the control end of the thyristor switch, and the other end of the switch K1 is grounded.
VSENThe voltage difference between two ends of the controlled silicon is represented as VSENJust greater than VCM+Vth1Or less than rigid VCM-Vth1When the ac input voltage is just higher than the voltages of the first capacitor C1 and the second capacitor C2, and the switch M1 is closed at the optimal turn-on time of the thyristor, a driving current is generated to drive the thyristor. Specifically, a current can be pumped or pumped between the thyristor control terminal and the second terminal MT2 to drive the controllable conduction. When the silicon controlled rectifier is conducted, the current of the capacitor charged by the alternating-current input voltage meets the maintaining current of the silicon controlled rectifier, and the driving current can be withdrawn so as to reduce the loss. Optionally, the driving circuit may further include a monostable flip-flop when VSENGreater than VCM+Vth1Or less than VCM-Vth1Then the monostable will send a first status signal which will control switch K1 to close.
Fig. 5 is a waveform diagram of the second embodiment of the control circuit of the present invention. Wherein VC1Is the voltage of the first capacitor, VC2Is the voltage of the second capacitor, VoutFor a DC output voltage, IdriveFor driving current pulse signals, IACFor the input current, V is derived from FIG. 5 when the AC input voltage is greater than the first capacitor voltageSENJust greater than VCM+Vth1Driving current pulse IdriveAnd driving the silicon controlled rectifier to be conducted. When the AC input voltage is just greater than the voltage of the second capacitor C2, VSENJust less than VCM-Vth1At this time, the current pulse I is drivendriveAnd at the moment, the silicon controlled rectifier is driven to be conducted. As can be seen from fig. 5, the thyristors are driven once for each positive and negative half cycle of the ac input voltage.
It should be noted that, in the voltage-doubling rectification mode, the thyristors are driven once respectively for the positive and negative half periods of the ac input voltage. Under the half voltage-doubling rectification mode, the silicon controlled rectifier can be respectively driven once in the positive half period and the negative half period of the alternating-current input voltage, but the driving is effective only in the half period; in other embodiments, the thyristor may be driven only once during either the positive or negative half-cycles of the ac input voltage.
Fig. 6 is a schematic circuit diagram of a third embodiment of the control circuit of the present invention. By indirectly sampling the alternating current input voltage, the first capacitor voltage and the second capacitor voltage, when the difference value of the input voltage and the first voltage is greater than a second threshold value, the silicon controlled switch is driven to be switched on, and the first voltage is the smaller value of the first capacitor voltage and the second capacitor voltage. And when the difference value between the input voltage and the first voltage is greater than a second threshold value, the alternating current input voltage is characterized to be just greater than the minimum value of the first capacitor voltage and the second capacitor voltage. The third embodiment is to sample the division of the AC input voltage, the first voltage and the second voltage, and the voltage of the first capacitor is the output voltage Vout-VMT2The voltage of the second capacitor is VMT2The divided AC input voltage V isLNSThe divided first capacitor voltage VC1SAnd the divided second capacitor voltage VC2SThe output is input to a comparison circuit which comprises a comparator U3, and the positive end input V of the comparator U3LNSAnd a negative terminal inputs VC1SAnd VC2SMinimum value of (2) and second threshold valueVth2Sum, i.e. Min (V)C1S，VC2S)+Vth2The comparator U3 outputs to the driver circuit. The driving circuit is the same as embodiment 2, and details thereof are not repeated.
It should be noted that the threshold of the present invention can be set according to the requirement. The utility model discloses all do not restrict.
Furthermore, the utility model discloses carry out the replacement of arbitrary part between embodiment one, embodiment two and the embodiment three and all be in the protection scope of the utility model.
In accordance with the present invention, as described above, these embodiments do not set forth all of the details nor limit the invention to the specific embodiments described. Obviously, many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and its various embodiments with various modifications as are suited to the particular use contemplated. The present invention is limited only by the claims and their full scope and equivalents.
Claims (15)
1. An ac-dc conversion circuit, comprising:
the rectifier circuit comprises a first input end, a second input end, a first output end and a second output end, wherein the first input end and the second input end are used for receiving alternating-current input voltage;
the first capacitor and the second capacitor are connected in series between the first output end and the second output end of the rectifying circuit;
a thyristor switch coupled between one of the first and second input terminals and a common terminal of the first and second capacitors;
and the control circuit controls the on-off state of the silicon controlled switch according to the value of the alternating current input voltage so as to reduce the fluctuation of the direct current output voltage of the alternating current-direct current conversion circuit when the alternating current input voltage has different values.
2. The ac-dc conversion circuit according to claim 1, wherein: when the alternating current input voltage is in a first voltage range, the control circuit controls the silicon controlled switch to be conducted so as to increase the direct current output voltage.
3. The ac-dc conversion circuit according to claim 2, wherein: when the alternating current input voltage is in a second voltage range, the control circuit controls the silicon controlled switch to be always turned off.
4. The ac-dc conversion circuit according to claim 2, wherein: when the alternating current input voltage is in a second voltage range, the first capacitor or the second capacitor is in short circuit, and the control circuit controls the silicon controlled switch to be switched on.
5. The ac-dc conversion circuit according to claim 4, wherein: one of the first capacitor and the second capacitor is connected with a diode in parallel.
6. The ac-dc conversion circuit according to claim 2 or 4, wherein: and in the positive half period and the negative half period of the alternating current input voltage, the control circuit controls the conduction times of the drive silicon controlled switch to be not more than 1 time.
7. The ac-dc conversion circuit according to claim 1, wherein: and when the absolute value of the difference value of the signals representing the voltages at the two ends of the silicon controlled switch is greater than the corresponding threshold value, driving the silicon controlled switch to be conducted.
8. The ac-dc conversion circuit according to claim 1, wherein: and when the difference value between the signal representing the alternating current input voltage and the first voltage is larger than the corresponding threshold value, the silicon controlled switch is driven to be conducted, wherein the first voltage is the smaller value of the signal representing the first capacitor voltage and the signal representing the second capacitor voltage.
9. The ac-dc conversion circuit according to claim 7, wherein: the control circuit detects the voltage at two ends of the silicon controlled switch, and drives the silicon controlled switch to be conducted when the absolute value of the difference value of the voltage at two ends of the silicon controlled switch is greater than a first threshold value.
10. The ac-dc conversion circuit according to claim 7, wherein: the control circuit detects the voltage division signals of the voltages at the two ends of the silicon controlled switch, and drives the silicon controlled switch to be conducted when the absolute value of the difference value of the voltage division signals of the voltages at the two ends of the silicon controlled switch is larger than a third threshold value.
11. The ac-dc conversion circuit of claim 9, wherein: and respectively superposing first signals on the detected voltage at one end of the silicon controlled switch and the first threshold, and driving the silicon controlled switch to be switched on when the absolute value of the difference value of the voltages at the two ends of the silicon controlled switch superposed with the first signals is greater than the value of the superposed first signals of the first threshold.
12. The ac-dc conversion circuit of claim 8, wherein: the control circuit detects the input voltage, the voltage of the first capacitor and the voltage of the second capacitor, when the difference value of the input voltage and the first voltage is larger than a second threshold value, the silicon controlled switch is driven to be conducted, and the first voltage is the smaller value of the voltage of the first capacitor and the voltage of the second capacitor.
13. The ac-dc conversion circuit of claim 8, wherein: the control circuit detects a voltage division signal of the input voltage, a voltage division signal of the first capacitor voltage and a voltage division signal of the second capacitor voltage, drives the silicon controlled switch to be switched on when a difference value of the voltage division signal of the input voltage and the second voltage is larger than a fourth threshold value, and the second voltage is a smaller value of the voltage division signal of the first capacitor voltage and the voltage division signal of the second capacitor voltage.
14. The ac-dc converter circuit of claim 2, wherein the control circuit adjusts the turn-on time of the thyristor switch to reduce the duration of the holding current of the thyristor switch.
15. The ac-dc converter circuit of claim 2, wherein the control circuit adjusts a turn-on time of the thyristor switch such that a charging current flowing through the first and second output terminals is greater than a holding current of the thyristor switch after the thyristor switch is turned on.
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| CN201920904649.4U CN209930164U (en) | 2019-06-14 | 2019-06-14 | AC-DC conversion circuit |
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| CN201920904649.4U CN209930164U (en) | 2019-06-14 | 2019-06-14 | AC-DC conversion circuit |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110190761A (en) * | 2019-06-14 | 2019-08-30 | 矽力杰半导体技术(杭州)有限公司 | AC-DC conversion circuit and method |
| CN111446872A (en) * | 2020-04-01 | 2020-07-24 | 石家庄通合电子科技股份有限公司 | Transformer transformation ratio adjustable wide-range constant power output switching circuit |
-
2019
- 2019-06-14 CN CN201920904649.4U patent/CN209930164U/en active Active
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110190761A (en) * | 2019-06-14 | 2019-08-30 | 矽力杰半导体技术(杭州)有限公司 | AC-DC conversion circuit and method |
| CN111446872A (en) * | 2020-04-01 | 2020-07-24 | 石家庄通合电子科技股份有限公司 | Transformer transformation ratio adjustable wide-range constant power output switching circuit |
| CN111446872B (en) * | 2020-04-01 | 2021-08-31 | 石家庄通合电子科技股份有限公司 | Transformer transformation ratio adjustable wide-range constant power output switching circuit |
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