CN100424966C - Circuitry and control method for charging capacitive loads - Google Patents
Circuitry and control method for charging capacitive loads Download PDFInfo
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- CN100424966C CN100424966C CNB2005100661344A CN200510066134A CN100424966C CN 100424966 C CN100424966 C CN 100424966C CN B2005100661344 A CNB2005100661344 A CN B2005100661344A CN 200510066134 A CN200510066134 A CN 200510066134A CN 100424966 C CN100424966 C CN 100424966C
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Abstract
A capacitor charging circuit comprises, power transfer circuitry, power switching control circuitry and voltage measurement circuitry. The power transfer circuitry transfers power from a power source to a capacitor. The power switching control circuitry controls the switching that causes power to be delivered to the power transfer circuitry. The voltage measurement circuitry indirectly measures the output voltage to determine when to stop charging the capacitor.
Description
Technical field
The present invention relates to capacitive load is charged, relate to the capacitor charging circuit of power controlling conversion and transmission more specifically.
Background technology
Capacitor charging circuit is used for to the capacitive load charging, for example is used for the capacitive load charging to the traditional photography flash system.In traditional capacitor charging circuit, by the power delivery of closed and disconnected mains switch control from the power supply to the capacitive load.Under the variable load situation or according to the requirement of output voltage, the monitoring output voltage is also adjusted switch to satisfy the requirement of output voltage and load.
Figure 1 shows that a traditional capacitance charging circuit 10.In this circuit 10, power is transferred to electric capacity (C by transformer 14
Out) 12.When mains switch 16 closures, the primary coil of electric current inflow transformer 14.When mains switch 16 disconnected, the energy that is stored in the transformer 14 was transferred to electric capacity 12.The output voltage V of the secondary coil of transformer 14
Out(R1 and R2) is monitored to by resitstance voltage divider 20.This monitoring V
OutThe shortcoming of method be exactly that the flow through leakage current of resistance R 1 and R2 can cause the loss of capacitive energy.
Be connected in the latch 18 response primary current I of comparator 24 and comparator 26
PriWith secondary current I
SecThe closed and disconnected of control mains switch 16.In case primary current I
PriSurpass a limit value, switch 16 disconnects, and the energy of transformer 14 is transferred to electric capacity 12.This primary current I that limits for current protection and charging control
PriMethod be that primary side at transformer 14 has adopted one to detect resistance 30.The shortcoming of the method for this current protection and charging control is a resistance R
PriCan cause power consumption.Secondary side at transformer 14 has also adopted one to detect resistance 32, in case and secondary current I
SecBe lower than a limit value, switch 16 is closed and begin a new charge cycle.
Therefore, need a kind of leakage current and power consumption be reduced to minimum capacitor charging circuit and charge control method.
Summary of the invention
In view of this, the invention provides a kind of capacitor charging circuit that is used for to capacitive load charging, this capacitor charging circuit comprises: the power delivery circuit is used for power from a power delivery to this capacitive load; The power transfer control circuit is used for controlling the power transfer of this power supply to this power delivery circuit, and power is transferred to this power delivery circuit in constant ON time like this; And tension measuring circuit, be used for measuring the output voltage of this power delivery circuit, when stop charging with decision to capacitive load, wherein, t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described power delivery circuit comprises a transformer, and the current changing rate in the elementary winding of described transformer is invariable.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described tension measuring circuit is measured described output voltage indirectly by the flyback voltage of measuring described transformer.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described tension measuring circuit comprises that one is converted to the circuit of a tested voltage to described flyback voltage, and described tension measuring circuit compares described tested voltage and a reference voltage.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described power transfer control circuit comprises a switch, described switch is controlled the power transfer of described power supply to described power delivery circuit.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described power transfer control circuit comprises constant ON time generator circuit, with deciding described constant ON time and allowing described switch to remain closed in constant ON time.
The capacitor charging circuit that is used for to capacitive load charging of the present invention; described power transfer control circuit comprises current foldback circuit; be used for detecting the generation of the overcurrent condition in the described transformer; wherein and if only if when not having overcurrent condition to take place, the closed described switch of described power transfer control circuit.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described power transfer control circuit comprises the DCM testing circuit, be used for detecting the generation of the DCM in the described transformer, when described DCM that wherein and if only if takes place, the closed described switch of described power transfer control circuit.
The capacitor charging circuit that is used for to capacitive load charging of the present invention; described power transfer control circuit comprises the conversion and control logic; in described DCM testing circuit of this conversion and control logical response and the described current foldback circuit at least one is used to provide the closed described switch of a changeover control signal.
The capacitor charging circuit that is used for to capacitive load charging of the present invention, described conversion and control logic receives a SLOW/FAST instruction of representing charge mode at a slow speed or fast charge mode, wherein and if only if under fast charge mode when not having overcurrent condition to take place, the closed described switch of described conversion and control logic, wherein under charge mode at a slow speed when not having overcurrent condition to take place and when DCM takes place, the described switch of described conversion and control logic closure.
The capacitor charging circuit that is used for to capacitive load charging of the present invention also comprises a blanking cycle generator, is used for producing a blanking cycle signal, and wherein said power transfer control circuit and described tension measuring circuit receive described blanking cycle signal.
The present invention also provides a kind of method to the capacitive load charging, wherein this capacitive load is connected to a transformer, be used for power from power delivery to this capacitive load, this method comprises: monitor this transformer, to detect the DCM in this transformer; Monitor this transformer, to detect the overcurrent condition in this transformer; If do not detect overcurrent condition, then start a power delivery change-over period that has constant ON time, wherein power is transferred to this transformer in this constant ON time, and power delivery is cut off after this constant ON time; With output voltage of measurement, with deciding the charging that when stops this capacitive load, wherein, described constant ON time t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant.
Method to the capacitive load charging of the present invention, described DCM that and if only if start the described power delivery change-over period when taking place.
Method to the capacitive load charging of the present invention is measured described output voltage when described power does not transmit.
Method to the capacitive load charging of the present invention is measured described output voltage indirectly by the flyback voltage of measuring described transformer.
Method to the capacitive load charging of the present invention, measure described output voltage and comprise: a flyback voltage is converted to tested voltage, and more described tested voltage and a reference voltage.
Method to capacitive load charging of the present invention is monitored described transformer, comprises to detect described DCM: monitor described transformer, with decision when the flyback voltage of described transformer be lower than a predetermined threshold.
Method to the capacitive load charging of the present invention, by the latch Closing Switch is set, described power transfer is described transformer extremely, and wherein disconnects described switch by the described latch of resetting, and described power transfer is cut off.
Method to the capacitive load charging of the present invention, starting the described power delivery change-over period comprises: determine described constant ON time by adopting constant ON time generator circuit, wherein said constant ON time generator circuit allows described switch to remain closed in described constant ON time.
The present invention also provides a kind of power transfer control circuit, being used for power controlling is converted to a transformer, wherein this transformer is with power delivery to a capacitive load, this power transfer control circuit comprises: DCM (DCM) testing circuit is used for detecting the DCM in this transformer; Overcurrent protection (OCP) circuit is used for detecting the overcurrent condition in this transformer; Be connected to the conversion and control logic of this D CM circuit and this OCP circuit, be used to provide a changeover control signal; A switch is used for responding this changeover control signal with this transformer of power transfer; With constant ON time generator circuit, this circuit is connected to this DCM testing circuit and this OCP circuit, this constant ON time generator circuit determines constant ON time and allows this switch to remain closed in this constant ON time, wherein, and described constant ON time t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant.
Power transfer control circuit of the present invention, when detecting described DCM and not detecting overcurrent condition, described conversion and control logic provides described changeover control signal.
Power transfer control circuit of the present invention, and if only if when not detecting overcurrent condition, and described conversion and control logic provides described changeover control signal.
Power transfer control circuit of the present invention, under charge mode at a slow speed when detecting described DCM and not detecting overcurrent condition, described conversion and control logic provides described changeover control signal, if and only if under fast charge mode when not detecting overcurrent condition, and described conversion and control logic provides described changeover control signal.
Power transfer control circuit of the present invention also comprises a blanking cycle generator, is used for producing a blanking cycle signal, and wherein said DCM testing circuit and described current foldback circuit receive described blanking cycle signal.
Power transfer control circuit of the present invention, also comprise a latch that is connected between described constant ON time generator circuit and the described switch, be used for closed described switch, the closed described switch of the described changeover control signal of wherein said responsive, and wherein said latch responds described constant ON time generator circuit later in described constant ON time and disconnects described switch.
The present invention also provides a kind of device, comprise: an integrated circuit, be used for controlling charging to capacitive load, capacitive load is connected to a transformer, and this integrated circuit is monitored this transformer and started a power delivery change-over period that has constant ON time, wherein this integrated circuit in this constant ON time with power transfer to this transformer, and wherein when after this constant time, the conversion of this integrated circuit rupturing duty, wherein, described constant ON time t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONFor the current changing rate in the elementary winding of constant and transformer invariable.
Device of the present invention, described integrated circuit receive a SLOW/FAST instruction of representing charge mode at a slow speed or fast charge mode.
Device of the present invention, described integrated circuit detects the overcurrent condition in the described transformer, and starts the described change-over period when not having overcurrent to take place.
Device of the present invention, described integrated circuit is used for detecting the DCM of described transformer, and starts the described change-over period when described DCM takes place and do not have overcurrent to take place.
In the present invention, capacitor charging circuit is by dropping to minimum with leakage current and power loss, thereby makes the charging of capacitive load more effective.
Description of drawings
Figure 1 shows that the circuit diagram of a traditional capacitance charging circuit;
Fig. 2 A is depicted as the schematic diagram of an embodiment of capacitor charging circuit;
Fig. 2 B is depicted as the schematic diagram of another embodiment of capacitor charging circuit;
Figure 3 shows that the circuit diagram of an embodiment of the output voltage measuring circuit that is used for capacitor charging circuit;
Figure 4 shows that the circuit diagram of an embodiment of the DCM (DCM) that is used for capacitor charging circuit and overcurrent protection (OCP) circuit;
Figure 5 shows that the circuit diagram of an embodiment of the constant ON time generator circuit that is used for capacitor charging circuit;
Figure 6 shows that the sequential chart of the waveform of expression power transfer control circuit under a kind of mode of operation; With
Figure 7 shows that the sequential chart of the waveform of expression power transfer control circuit under another kind of mode of operation.
Embodiment
Usually, capacitor charging circuit charge to a capacitive load by starting a power delivery change-over period, and in this power delivery in the change-over period, power supply is closure in a constant time that is called ON time.After constant time or ON time, power supply disconnects.Capacitor charging circuit monitoring voltage value decides when start another power delivery change-over period.But capacitor charging circuit also indirect monitoring output voltage values decides the charging that when finishes electric capacity.
It is the high voltage that produces camera flashlamp that a typical case of capacitor charging circuit uses.Capacitor charging circuit can be used as digital device, for example the power-supply management system of a digital camera part.Skilled in the art will recognize that capacitor charging circuit also can be used in other application and the equipment.Used " circuit " of the arbitrary embodiment of this paper can comprise, for example, and single permanent circuit, programmable circuit, state machine circuit, and/or store the firmware of the instruction of carrying out by programmable circuit or the combination in any of these circuit.Used " integrated circuit " of the arbitrary embodiment of this paper is semiconductor device and/or microelectronic component, for example a semiconductor integrated circuit chip.
Fig. 2 A is depicted as an embodiment to the capacitor charging circuit 100 of capacitive load charging.This typical capacitance charging circuit 100 comprises power delivery circuit 101, power transfer control circuit 102 and tension measuring circuit 104.Power supply 106, for example a battery is connected in power delivery circuit 101, power transfer control circuit 102 and tension measuring circuit 104.Capacitive load or electric capacity 112 are connected in power delivery circuit 101.Power transfer control circuit 102 and/or tension measuring circuit 104 can be made up of discrete elements, or an integrated circuit.Although hereinafter the exemplary embodiments of described circuit all has its special construction or design, those skilled in the art understand that other circuit structure and design also can realize function described herein.
Exemplary power transmission circuit 101 comprises a transformer 114, kickback transformer that has primary and secondary coil or winding for example, and wherein the polarity of primary and secondary coil or winding is opposite.When power supply 106 powered for the elementary winding of transformer 114, power was transferred to transformer 114.When power supply 106 was no longer given transformer 114 power supplies, power transferred to electric capacity 112 from transformer 114, thereby to electric capacity 112 chargings.An output diode 108 is connected between electric capacity 112 and the transformer 114, is used for preventing that electric capacity 112 from being discharged by transformer 114 when power is transferred to transformer 114.
Power transfer control circuit 102 is by the conversion of starting power transmission change-over period control power supply 106 to transformer 114, this power transfer in the cycle power supply in constant time or ON time closure.In constant ON time, power transfer control circuit 102 makes power continue to transfer to transformer 114, and irrelevant with the electric current of the elementary winding of the transformer 114 of flowing through.Tension measuring circuit 104 is measured output voltage indirectly with deciding the charging that when stops electric capacity 112.
Exemplary power conversion control circuit 102 comprises a mains switch 116, and when trigger or latch 118 made switch 116 closed, power was transferred to transformer 114.Latch 118 makes switch 116 closures in constant ON time, and switch 116 is disconnected in constant ON time later the time.For the switching of control switch 116, exemplary power conversion control circuit 102 also comprises constant ON time generator circuit 120, DCM (DCM), testing circuit 130 and overcurrent protection (OCP) circuit 140.The constant ON time of constant 120 decision power delivery change-over periods of ON time generator circuit.DCM testing circuit 130 detects the generation of DCM, for example when the magnetic flux of transformer 114 disappears.OCP circuit 140 provides overcurrent protection by the current value that detects transformer 114, will cause an extra electric current (overcurrent condition) when switch 116 closures.
In an embodiment of control circuit 102, in when, overcurrent condition not taking place when DCM takes place, start another power delivery change-over period, and switch 116 is closed in constant ON time, this constant ON time is by constant ON time generator circuit 120 decisions.In one embodiment, power transfer control circuit 102 comprises a gate 144 (for example and door) that is connected to DCM testing circuit 130 and OCP circuit 140, is used to provide the FI RE signal of a changeover control signal or a starting power transmission change-over period.In this embodiment, the DCM signal of DCM (for example DCM=1) takes place, and when receiving an OCP output signal when representing not have overcurrent condition generation (OCP=1), gate 144 provides this FIRE signal (FIRE=1) when receiving an expression.
In the embodiment of control circuit 102, the FIRE signal sets latch 118 that is provided by gate 144 comes Closing Switch 116, and trigger constant ON time generator circuit 120 and make switch 116 conducting in constant ON time, thereby start another power delivery change-over period.After the constant ON time by constant ON time generator circuit 120 decisions, constant ON time generator circuit 120 replacement latchs 118 come cut-off switch 116.
Power transfer control circuit 102 also comprises a blanking cycle generator 150, is used for producing a blanking cycle signal and offers tension measuring circuit 104, DCM testing circuit 130 and OCP circuit 140.This blanking cycle signal can be used for the output (promptly during blanking cycle) of temporary transient cancellation or delay circuit, is used for preventing the rub-out signal that caused by voltage peak, for example when switch is disconnected for the first time.Those skilled in the art will know that the multiple circuit structure that can produce blanking cycle.
Fig. 2 B is depicted as another embodiment 100 ' of capacitor charging circuit.In this embodiment, electric capacity charging current 100 ' is operated at a slow speed under the charge mode and fast charge mode.Under charge mode at a slow speed, when overcurrent condition (current value of transformer is lower than a set point) not taking place, the starting power transmission change-over period, as indicated above when DCM when disappearing (be transformer flux) takes place.Under fast charge mode, and if only if when not producing overcurrent condition, the starting power transmission change-over period, need not to detect DCM.
In order to realize in an embodiment at a slow speed/fast charge mode, power transfer control circuit 102 ' comprises a gate 131 (for example or), and this gate 131 is connected between DCM testing circuit 130 and the gate 144.Gate 131 receives a SLOW/FAST instruction, for example from the instruction of external control circuit.In this embodiment, when receiving an OCP output signal (OCP=1), and when obtaining a DCM output signal (DCM=1) or during when this SLOW/FAST instruction expression fast charge mode (SLOW/FAST=1), gate 144 provides FIRE signal (FIRE=1).In other words, under fast charge mode, can ignore the DCM signal, and only send the FIRE signal, even without DCM (DCM=0) takes place according to the OCP output signal.
Figure 3 shows that an embodiment of tension measuring circuit 104.When tested voltage reached a predetermined value, tension measuring circuit 104 stopped the charging to electric capacity 112.When switch 116 disconnected, exemplary voltages measuring circuit 104 was measured the output voltage V of process transformer 114 primary coils indirectly by measuring flyback pulse
OutMore specifically be that exemplary voltages measuring circuit 104 is at node 117 receiving key voltage V
SwWith supply voltage V
BATAnd determine tested voltage V
R2, this tested voltage V
R2With a reference voltage V
REFCompare.In this embodiment, a cathode-input amplifier 160 is used as a level translator, and week converts this flyback voltage to tested voltage V
R2Tested voltage V
R2Provide by following formula:
V
R2＝R2/R1×(V
out/N) (1)
Wherein R1 and R2 are the resistance value of resistance 162,164, and N is secondary-primary transformers turn ratio, V
Out/ N represents flyback voltage.
Cathode-input amplifier 160 is realized by adopting a p channel metal oxide semiconductor (PMOS) M2.Tension measuring circuit 104 comprises biasing circuit 166, is used for guaranteeing I
2=I
3, the grid of M1 and M2-source voltage V like this
GSJust equated.In this case, the source voltage of cathode-input amplifier 160 just equals source voltage V
BAT
Stopping between charge period, because the intrinsic leakage current of diode 108 and/or electric capacity 112, the voltage of electric capacity can descend.In order to begin to charge once more, microprocessor or associated external control circuit can wake capacitor charging circuit 100 up later a scheduled time, and will consider the electric capacity pressure drop of permission.For example stop the latch 118 of resetting, thereby allow to start once more a power delivery change-over period.Closure-the break period of capacitor charging circuit will be according to the sequential decision renewal frequency of microprocessor or associated external control circuit.
In photoflash was used, microprocessor and associated external control circuit began that 112 discharges are used for producing flash of light to electric capacity.Subsequently, microprocessor and associated external control circuit start capacitor charging circuit 100 once more, thereby allow starting a power delivery change-over period realizes charging to electric capacity 112.
Figure 4 shows that the embodiment of DCM testing circuit 130 and current foldback circuit 140.When the magnetic flux complete obiteration of transformer 114 and flyback voltage equaled 0, a DCM (DCM) took place in the transformer 114.In order to detect DCM, DCM testing circuit 130 receiving key voltage V
SWWith source voltage V
BAT, and judge whether flyback voltage is lower than a predetermined threshold.Because switching voltage V
SWThe gate breakdown voltage that may be higher than a transformer in the low-voltage process so DCM testing circuit 130 can comprise a resitstance voltage divider 134, is used for weakening voltage V
SWTo a safety value in order to further handling.
K×V
SW+V
GS＝K×V
BAT+V
GS+I
bias1×R
offset (2)
∴V
SW＝V
BAT?+V
offset/K (3)
Like this, approximate source voltage (V when switching voltage
SW=V
BAT) time, comparator 132 provides DCM output signal, and (being DCM=1) takes place in expression DCM.
In the original charge period, work as output voltage V
OutDuring near 0V, the amplitude of flyback pulse is very little and can be less than the threshold value of DCM.DCM testing circuit 130 detects less than a so little voltage, and the result is even without DCM takes place, and DCM testing circuit 130 also can produce a DCM output signal (DCM=1).If in this case the starting power transmission change-over period, the primary current of transformer 114 will increase and surpass the restriction electric current of switch 116 and transformer 114.
When transformer generation overcurrent condition, typical OCP circuit 140 prevents that by the closure that stops switch 116 primary current from surpassing the restriction electric current of switch 116 and transformer 114.OCP circuit 140 receives bias current I
Bias3, I
Bias4With one in resistance R
SecThe overcurrent protection voltage V that two ends record
OCPOCP circuit 140 comprises a comparator 142, and this comparator is according to voltage V
OCPWhether surpass a determined value by the current value of judging transformer 114 and detect overcurrent condition, as shown in the formula:
V
OCP+V
GS+R
offset×I
bias＝V
GS (4)
V
OCP＝-I
sec_valley×R
sec (5)
Like this, the mistake flow valuve of transformer secondary output winding is:
The corresponding flow valuve of crossing of primary winding is:
I
p_valley＝I
sec_valley×N (7)
If the current value of transformer secondary output winding is lower than I
Sec_valley, comparator 142 produces OCP output signal (being OCP=1), and expression does not have overcurrent condition.
Figure 5 shows that the embodiment of a constant ON time generator circuit 120.As indicated above, FIRE signal sets trigger or latch 118 make switch 116 closures, and trigger constant ON time generator circuit 120.According to described embodiment, constant ON time generator circuit 120 comprises a latch 121, and this latch receives the FIRE signal.Constant ON time generator circuit 120 reception sources voltage V
BAT, this source voltage is by dividing potential drop and be added in the current feedback circuit that is positioned at around the operational amplifier 122, and this operational amplifier 122 links to each other with a nmos pass transistor.With V
BATThe leakage current of proportional nmos pass transistor is transferred into current mirror 123.When FIRE signal triggering latch 121, its output signal CHARGE driving switch 124 makes the electric current of current mirror 123 mappings flow to electric capacity 125.Electric capacity 125 with V
BATProportional electric current charges:
I
charge＝k×V
BAT (8)
The voltage of electric capacity 125 is from initial value V
RAMP_LIncrease to V
RAMP_HComparator 128 detects when capacitance voltage reaches V
RAMP_HAnd output signal PK_DETECT, this signal replacement latch or trigger 118 and 129.Trigger 129 starts capacitor discharging circuit, and replacement latch 121.After electric capacity 125 was by discharge, comparator 127 is provided with trigger 129 made it prepare a new cycle.The output Q of trigger 118 is made as height always when the FIRE signal is provided with, reset by the PK_DETECT signal up to it.ON time t
OnFor:
Like this, ON time and source voltage V
BATBe inversely proportional to.
The corresponding electrorheological of switch 116 and transformer 114 elementary windings of flowing through turns to:
Δ I wherein
pFor the electric current in the primary winding changes, L
pBe primary inductance, K
ONBe a constant:
The peak current of primary winding is:
I
p_pk＝I
p_valley+ΔI
p (12)
Because it is invariable that typical OCP circuit 140 prevents that under overcurrent condition charging and constant ON time generator circuit 120 holding currents from changing, so power transfer control circuit 102 need not directly to monitor elementary restriction electric current and can remove the sensing resistor of using in the traditional capacitance charging circuit.
Although exemplary embodiments only shows a kind of structure of constant ON time generator circuit 120, skilled in the art will recognize that other structure also can provide constant ON time.
Figure 6 shows that power transfer control circuit 102 and be operated in the multiple waveform correlation of the embodiment of the power transfer control circuit 102 ' under the charge mode (being DCM) at a slow speed.When switch at constant ON time (t
On) when closed, switching voltage V
SWBe reduced to zero and primary current I
PriIncrease.After constant ON time, switch disconnects, primary current I
PriReduce to zero and switching voltage V
SWIncrease.In order to compensate elementary induced flux, electric current I
SECThe secondary winding of flowing through, its initial value is I
SEC=I
P_PK/ N.In opening time, secondary current I
SECReduce.When the magnetic flux of transformer disappear and flyback voltage to equal zero (be V
SW=V
BAT) time, produce DCM output signal (DCM=1).As long as overcurrent condition does not take place, just produce overcurrent protection signal (OCP=1).When OCP=1 and DCM=1, switch is at another closing time (t
On) in closed once more.If work as V
OutFlyback voltage is decreased in the period in initial charge and is lower than the DCM threshold value and produces DCM output signal 200 near zero the time, if OCP=0, switch will be not closed so.In the present embodiment, when switch disconnects for the first time, blanking cycle (BP) takes place, and is used for preventing the error signal that is caused by voltage peak.
Figure 7 shows that the multiple waveform of the embodiment that is operated in the power transfer control circuit 102 ' under the fast charge mode (being continuous current work).During fast charge mode, when and when just thinking OCP=1 switch at closed ON time (t
On) interior closed.As a result, as secondary current I
SECBe decreased to the value of setting I
ValleyShi Kaiguan is closed before DCM takes place.When switch closure, corresponding electric current I in the elementary winding
PriEqual N * I
ValleyThereby, with a continuous current job.
In a word, a capacitor charging circuit comprises: the power delivery circuit is used for from a power delivery power to capacitive load; The power transfer control circuit is used for controlling the power transfer of power supply to the power delivery circuit, and power is transferred to the power delivery circuit in a constant ON time like this; And tension measuring circuit, when the output voltage that is used for measuring the power delivery circuit stops charging to capacitive load with decision.The method that capacitive load is charged comprises transformer of monitoring, to detect the DCM and the overcurrent condition of monitoring in the transformer detection transformer in the transformer.If detect DCM and/or do not detect overcurrent condition, then starting power is transmitted the change-over period.There is a constant ON time power delivery change-over period, and power is converted to transformer in constant ON time like this, and power transfer is cut off after constant ON time.Measure output voltage with deciding the charging that when stops capacitive load.
Therefore, capacitor charging circuit is by dropping to minimum with leakage current and power loss, thereby makes the charging of capacitive load more effective.
Term used herein and phrase just are used for describing, but do not limit this.In the use of term and phrase, do not repel the equivalent of the shown and feature (or Partial Feature) described of any this paper of having.And, should be understood that to have various possible modifications within the scope of the claims.Also exist other modifications, variation and replacement.Therefore, claim is intended to contain all equivalents.
Claims (34)
1. capacitor charging circuit that is used for to capacitive load charging is characterized in that described capacitor charging circuit comprises:
The power delivery circuit is used for power from a power delivery to described capacitive load;
The power transfer control circuit is used for controlling the power transfer of described power supply to described power delivery circuit, and power is transferred to described power delivery circuit in constant ON time like this; With
Tension measuring circuit is used for measuring the output voltage of described power delivery circuit, when stops charging to capacitive load with decision,
Wherein, described constant ON time t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant.
2. the capacitor charging circuit that is used for to capacitive load charging according to claim 1, it is characterized in that: described power delivery circuit comprises a transformer, and the current changing rate in the elementary winding of described transformer is invariable.
3. the capacitor charging circuit that is used for to capacitive load charging according to claim 2, it is characterized in that: described tension measuring circuit is measured described output voltage indirectly by the flyback voltage of measuring described transformer.
4. the capacitor charging circuit that is used for to capacitive load charging according to claim 3, it is characterized in that: described tension measuring circuit comprises that one is converted to the circuit of a tested voltage to described flyback voltage, and described tension measuring circuit compares described tested voltage and a reference voltage.
5. the capacitor charging circuit that is used for to capacitive load charging according to claim 1, it is characterized in that: described power transfer control circuit comprises a switch, described switch is controlled the power transfer of described power supply to described power delivery circuit.
6. the capacitor charging circuit that is used for to capacitive load charging according to claim 5, it is characterized in that: described power transfer control circuit comprises constant ON time generator circuit, with deciding described constant ON time and allowing described switch to remain closed in constant ON time.
7. the capacitor charging circuit that is used for to capacitive load charging according to claim 5, it is characterized in that: described power delivery circuit comprises a transformer.
8. the capacitor charging circuit that is used for to capacitive load charging according to claim 7; it is characterized in that: described power transfer control circuit comprises current foldback circuit; be used for detecting the generation of the overcurrent condition in the described transformer; wherein and if only if when not having overcurrent condition to take place, the closed described switch of described power transfer control circuit.
9. the capacitor charging circuit that is used for to capacitive load charging according to claim 8, it is characterized in that: described power transfer control circuit comprises the DCM testing circuit, be used for detecting the generation of the DCM in the described transformer, when described DCM that wherein and if only if takes place, the closed described switch of described power transfer control circuit.
10. the capacitor charging circuit that is used for to capacitive load charging according to claim 9; it is characterized in that: described power transfer control circuit comprises the conversion and control logic; in described DCM testing circuit of this conversion and control logical response and the described current foldback circuit at least one is used to provide the closed described switch of a changeover control signal.
11. the capacitor charging circuit that is used for to capacitive load charging according to claim 10, it is characterized in that: described conversion and control logic receives a SLOW/FAST instruction of representing charge mode at a slow speed or fast charge mode, wherein and if only if under fast charge mode when not having overcurrent condition to take place, the closed described switch of described conversion and control logic, wherein under charge mode at a slow speed when not having overcurrent condition to take place and when DCM takes place, the described switch of described conversion and control logic closure.
12. the capacitor charging circuit that is used for to capacitive load charging according to claim 1, it is characterized in that: also comprise a blanking cycle generator, be used for producing a blanking cycle signal, wherein said power transfer control circuit and described tension measuring circuit receive described blanking cycle signal.
13. the method to capacitive load charging is characterized in that described capacitive load is connected to a transformer, is used for power from power delivery to described capacitive load, described method comprises:
Monitor described transformer, to detect the DCM in the described transformer;
Monitor described transformer, to detect the overcurrent condition in the described transformer;
If do not detect overcurrent condition, then start a power delivery change-over period that has constant ON time, wherein power is transferred to described transformer in described constant ON time, and power delivery is cut off after described constant ON time; With
Measure an output voltage, use and decide the charging that when stops described capacitive load,
Wherein, described constant ON time t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant.
14. the method to the capacitive load charging according to claim 13 is characterized in that: described DCM that and if only if starts the described power delivery change-over period when taking place.
15. the method to the capacitive load charging according to claim 13 is characterized in that: measure described output voltage when described power does not transmit.
16. the method to the capacitive load charging according to claim 13 is characterized in that: measure described output voltage indirectly by the flyback voltage of measuring described transformer.
17. the method to the capacitive load charging according to claim 13 is characterized in that: measure described output voltage and comprise: a flyback voltage is converted to tested voltage, and more described tested voltage and a reference voltage.
18. the method to the capacitive load charging according to claim 13, it is characterized in that: monitor described transformer, comprise to detect described DCM: monitor described transformer, with decision when the flyback voltage of described transformer be lower than a predetermined threshold.
19. the method to the capacitive load charging according to claim 13, it is characterized in that: by the latch Closing Switch is set, described power transfer is described transformer extremely, and wherein disconnects described switch by the described latch of resetting, and described power transfer is cut off.
20. the method to the capacitive load charging according to claim 19, it is characterized in that: starting the described power delivery change-over period comprises: determine described constant ON time by adopting constant ON time generator circuit, wherein said constant ON time generator circuit allows described switch to remain closed in described constant ON time.
21. the method to capacitive load charging according to claim 13 is characterized in that: receives a SLOW/FAST who represents charge mode at a slow speed or fast charge mode and instruct.
22. the method to the capacitive load charging according to claim 21, it is characterized in that: and if only if under fast charge mode when not having overcurrent condition to take place, described power delivery is to described transformer, under charge mode at a slow speed when not having overcurrent condition to take place and when DCM takes place, described power delivery is described transformer extremely.
23. a power transfer control circuit is used for power controlling to be converted to a transformer, it is characterized in that described transformer with power delivery to a capacitive load, described power transfer control circuit comprises:
The DCM testing circuit is used for detecting the DCM in the described transformer;
Current foldback circuit is used for detecting the overcurrent condition in the described transformer;
Be connected to the conversion and control logic of described DCM testing circuit and described current foldback circuit, be used to provide a changeover control signal;
A switch, be used for responding described changeover control signal with power transfer to described transformer; With
Constant ON time generator circuit; this circuit is connected to described DCM testing circuit and described current foldback circuit; described constant ON time generator circuit determines constant ON time and allows described switch to remain closed in described constant ON time
Wherein, described constant ON time t
OnWith a source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant.
24. power transfer control circuit according to claim 23 is characterized in that: when detecting described DCM and not detecting overcurrent condition, described conversion and control logic provides described changeover control signal.
25. power transfer control circuit according to claim 23 is characterized in that: and if only if when not detecting overcurrent condition, and described conversion and control logic provides described changeover control signal.
26. power transfer control circuit according to claim 23, it is characterized in that: under charge mode at a slow speed when detecting described DCM and not detecting overcurrent condition, described conversion and control logic provides described changeover control signal, if and only if under fast charge mode when not detecting overcurrent condition, and described conversion and control logic provides described changeover control signal.
27. power transfer control circuit according to claim 23; it is characterized in that: also comprise a blanking cycle generator; be used for producing a blanking cycle signal, wherein said DCM testing circuit and described current foldback circuit receive described blanking cycle signal.
28. power transfer control circuit according to claim 23, it is characterized in that: also comprise a latch that is connected between described constant ON time generator circuit and the described switch, be used for closed described switch, the closed described switch of the described changeover control signal of wherein said responsive, and wherein said latch responds described constant ON time generator circuit later in described constant ON time and disconnects described switch.
29. power transfer control circuit according to claim 23 is characterized in that: described conversion and control logic receives a SLOW/FAST instruction of representing charge mode at a slow speed or fast charge mode.
30. power transfer control circuit according to claim 29, it is characterized in that: and if only if under fast charge mode when not having overcurrent condition to take place, the closed described switch of described conversion and control logic, under charge mode at a slow speed when not having overcurrent condition to take place and when DCM takes place, the described switch of described conversion and control logic closure.
31. a device is characterized in that comprising:
An integrated circuit, be used for controlling charging to capacitive load, capacitive load is connected to a transformer, described integrated circuit is monitored described transformer and is started a power delivery change-over period that has constant ON time, wherein said integrated circuit in described constant ON time with power transfer to described transformer, and wherein work as after the described constant time conversion of described integrated circuit rupturing duty
Wherein, described constant ON time t
OnWith source voltage V
BATBetween the pass be: t
On=K
ON/ V
BAT, wherein, K
ONBe constant, and the current changing rate in the elementary winding of described transformer is invariable.
32. device according to claim 31 is characterized in that: described integrated circuit receives a SLOW/FAST instruction of representing charge mode at a slow speed or fast charge mode.
33. device according to claim 31 is characterized in that: described integrated circuit detects the overcurrent condition in the described transformer, and starts the described change-over period when not having overcurrent to take place.
34. device according to claim 33 is characterized in that: described integrated circuit is used for detecting the DCM of described transformer, and starts the described change-over period when described DCM takes place and do not have overcurrent to take place.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US56390204P | 2004-04-21 | 2004-04-21 | |
| US60/563,902 | 2004-04-21 | ||
| US60/564,395 | 2004-04-22 | ||
| US10/943,322 | 2004-09-17 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1700560A CN1700560A (en) | 2005-11-23 |
| CN100424966C true CN100424966C (en) | 2008-10-08 |
Family
ID=35476473
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2005100661344A Expired - Fee Related CN100424966C (en) | 2004-04-21 | 2005-04-21 | Circuitry and control method for charging capacitive loads |
| CN200520016971.1U Expired - Lifetime CN2829178Y (en) | 2004-04-21 | 2005-04-21 | Capacitance charge circuit for capacitive load charging |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN200520016971.1U Expired - Lifetime CN2829178Y (en) | 2004-04-21 | 2005-04-21 | Capacitance charge circuit for capacitive load charging |
Country Status (1)
| Country | Link |
|---|---|
| CN (2) | CN100424966C (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4916711B2 (en) * | 2005-12-09 | 2012-04-18 | ローム株式会社 | DC / DC converter control circuit, control method, and light emitting device and electronic apparatus using the same |
| US8300431B2 (en) * | 2010-03-05 | 2012-10-30 | Hong Kong Applied Science And Technology Research Institute Co., Ltd. | Constant-current control module using inverter filter multiplier for off-line current-mode primary-side sense isolated flyback converter |
| US8780590B2 (en) * | 2012-05-03 | 2014-07-15 | Hong Kong Applied Science & Technology Research Institute Company, Ltd. | Output current estimation for an isolated flyback converter with variable switching frequency control and duty cycle adjustment for both PWM and PFM modes |
| CN102751874B (en) * | 2012-06-27 | 2015-01-07 | 电子科技大学 | Self-adaptive constant-on-time control circuit |
| CN104038050B (en) * | 2013-03-08 | 2016-09-14 | 乐星产电(无锡)有限公司 | Busbar voltage sampling apparatus |
| CN103802763B (en) * | 2014-02-20 | 2015-12-30 | 中国北方车辆研究所 | A kind of armored vehicle high direct voltage big current combination power distribution protective device |
| TWI646767B (en) * | 2017-05-22 | 2019-01-01 | 偉詮電子股份有限公司 | Power control device and power control system |
| KR20210081782A (en) * | 2019-12-24 | 2021-07-02 | 한국전기연구원 | System for controlling capacitor voltage of ccm resonance type converter, and ccm resonance type converter comprising capacitor voltage control system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN1198850A (en) * | 1996-06-21 | 1998-11-11 | 菲利浦电子有限公司 | Power supply system for an apparatus with rechargeable batteries, and power supply unit and apparatus for such a power supply system |
| US6219493B1 (en) * | 1998-08-19 | 2001-04-17 | Konica Corporation | Electronic flash device of a separate excitation oscillating type |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN1700560A (en) | 2005-11-23 |
| CN2829178Y (en) | 2006-10-18 |
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