Driver circuit and power supply

Abstract

An embodiment of the present application provides a driver circuit and a power supply. The driver circuit has a voltage conversion unit that converts an input DC voltage into an output DC voltage. The voltage conversion unit has a switching element, a capacitive element, and a diode, and the voltage conversion unit also has an inductive element or a transformer. Among them, the switching element controls the conversion of the input DC voltage into the output DC voltage by conduction or disconnection. The driver circuit further has: an output current detection unit that detects an output current generated when the output DC voltage is applied to an external element; a control unit that has a first control part. The first control part multiplies the difference between the current value of the output current and a target current value by a gain, and generates a first control signal according to the value after multiplying by the gain. The control unit also has a control signal generation part that generates a control signal for controlling the conduction and disconnection of the switching element according to the first control signal. Among them, the first control part adjusts the gain according to the target current value.

Description

Technical Field

[0001] This application relates to the field of electronic circuits, and particularly to a driver circuit and a power supply. Background Art

[0002] In the prior art, various methods or circuits for dimming control of light-emitting diodes (LEDs) have been proposed.

[0003] For example, in Prior Art 1, in order to set the dimming rate of an LED to a wide range including 0% to 10%, a combination of pulse width modulation (PWM) dimming and analog dimming is used; in Prior Art 2, when the dimming rate is in a range close to 0 (for example, 5% or less), the dimming is switched from linear dimming to PWM dimming; in Prior Art 3, an LED power supply circuit is provided that can perform dimming control of the driving current of the LED without interruption starting from zero percentage; in addition, in Prior Art 4, it is proposed to perform dimming control by a microcomputer without performing feedback control.

[0004] In the above description, the dimming rate refers to the ratio between the target current value set for the light-emitting diode and the rated current value of the light-emitting diode.

[0005]

Prior Art 1

[0006]

Prior Art 2

[0007]

Prior Art 3

[0008]

Prior Art 4

[0009] It should be noted that the above introduction of the technical background is only for the convenience of clearly and completely explaining the technical solution of this application and facilitating the understanding of those skilled in the art. It cannot be considered that the above technical solutions are well-known to those skilled in the art just because these solutions are described in the background art part of this application. Summary of the Invention

[0010] The inventors of this application have found that the prior art has some limitations. For example, in Prior Arts 1 and 2, different dimming methods are combined, so the circuit is relatively complex; in Prior Art 3, when the dimming rate is low, the LED current value as the control object becomes small. Therefore, the signal-to-noise ratio (S / N) deteriorates, making the LED current value unstable with respect to the target value and causing flickering; in Prior Art 4, since no feedback control of the LED current is performed, the individual deviation of the lighting device will cause the brightness of each lighting device to be different at the same dimming rate.

[0011] An embodiment of the present application provides a driver circuit and a power supply, which adjust the gain used in feedback control according to a target current value. Thus, the instability of the current when the target current value is small can be avoided, and the structure is simple.

[0012] According to a first aspect of the embodiments of the present application, a driver circuit is provided, which has a voltage conversion unit that converts an input DC voltage into an output DC voltage. The voltage conversion unit has a switching element, a capacitive element, and a diode, and the voltage conversion unit also has an inductive element or a transformer. Among them, the switching element controls the conversion of the input DC voltage into the output DC voltage by conduction or disconnection.

[0013] The driver circuit further has:

[0014] An output current detection unit that detects the output current generated when the output DC voltage is applied to an external element;

[0015] A control unit that has a first control part. The first control part multiplies the difference between the current value of the output current and the target current value by a gain, and generates a first control signal according to the value after multiplying by the gain. The control unit also has a control signal generation part that generates a control signal for controlling the conduction and disconnection of the switching element according to the first control signal. Among them, the first control part adjusts the gain according to the target current value.

[0016] According to a second aspect of the embodiments of the present application, a power supply is provided, which has a voltage input unit and the driver circuit described in the first aspect above. Among them, the voltage input unit inputs a DC voltage to the input terminal of the driver circuit, and the voltage input unit includes: a DC power supply; or an AC power supply, and a rectifying and smoothing circuit or a power factor correction (PFC) circuit connected to the AC power supply.

[0017] The beneficial effect of the present application is that: the gain used in feedback control is adjusted according to the target current value. Thus, the instability of the current when the target current value is small can be avoided, and the structure is simple.

[0018] Referring to the following description and the accompanying drawings, specific embodiments of the present application are disclosed in detail, indicating the ways in which the principles of the present application can be adopted. It should be understood that the embodiments of the present application are not limited in scope thereby. Within the spirit and terms of the appended claims, the embodiments of the present application include many changes, modifications, and equivalents.

[0019] Features described and / or illustrated for one embodiment can be used in the same or similar way in one or more other embodiments, combined with features in the other embodiments, or instead of features in the other embodiments.

[0020] It should be emphasized that the term "comprising / including" as used herein refers to the presence of features, whole things, steps or components, but does not exclude the presence or addition of one or more other features, whole things, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings included are used to provide a further understanding of the embodiments of the present application, which form a part of the specification, illustrate the embodiments of the present application, and together with the written description explain the principles of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0022] Figure 1 is a schematic diagram of a driver circuit according to an embodiment of the present application;

[0023] Figure 2 is Figure 1 a schematic diagram of the composition of the control unit 11 of the driver circuit shown;

[0024] Figure 3 is a schematic diagram of the gain varying with the target current value Itg according to an embodiment of the present application;

[0025] Figure 4 is another schematic diagram of the gain varying with the target current value Itg according to an embodiment of the present application;

[0026] Figure 5a is a schematic diagram of the control signal generation unit of this embodiment;

[0027] Figure 5b is a schematic diagram of each signal in the control signal generation unit of this embodiment;

[0028] Figure 6 is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0029] Figure 7 is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0030] Figure 8a is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0031] Figure 8b is Figure 8a a schematic diagram of the control unit 11 of the driver circuit of

[0032] Figure 8c is Figure 8a a timing diagram of some signals in the driver circuit of

[0033] Figure 8d is Figure 8a a timing diagram of some signals in the circuit when FF control is introduced to the driver circuit of

[0034] Figure 9a is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0035] Figure 9b is Figure 9a a timing diagram of some signals in the circuit when FF control is introduced to the driver circuit of

[0036] Figure 10a is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0037] Figure 10b is Figure 10a a timing diagram of some signals in the circuit when FF control is introduced to the driver circuit of

[0038] Figure 11 is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0039] Figure 12 is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0040] Figure 13 is another schematic diagram of the driver circuit according to an embodiment of the present application;

[0041] Figure 14 is Figure 13 a schematic diagram of the control unit 11 of the driver circuit shown in

[0042] Figure 15 is a schematic diagram of the power supply according to an embodiment of the present application;

[0043] Figure 16 is another schematic diagram of the power supply according to an embodiment of the present application;

[0044] Figure 17 is an actual circuit diagram of the power supply according to an embodiment of the present application. Detailed implementation manners

[0045] Referring to the accompanying drawings, the foregoing and other features of the present application will become apparent from the following description. In the description and drawings, specific embodiments of the present application are specifically disclosed, which show some embodiments in which the principles of the present application can be adopted. It should be understood that the present application is not limited to the described embodiments. On the contrary, the present application includes all modifications, variations, and equivalents falling within the scope of the appended claims.

[0046] Embodiment 1

[0047] Embodiment 1 of the present application provides a driver circuit that can provide a DC voltage for an external component. Among them, the external component can be, for example, an array of LEDs or other components using direct current. In the embodiment of the present application, the case where the external component is an array of LEDs will be taken as an example for description, but the embodiment of the present application is not limited thereto, and the driver circuit can also provide a DC voltage for other external components. Figure 1 FIG. is a schematic diagram of the driver circuit 1 according to the embodiment of the present application.

[0048] As Figure 1 shown, the driver circuit 1 has a voltage conversion unit 10 that converts the input DC voltage Vin into an output DC voltage. The voltage conversion unit 10 has a switching element Q1, a capacitive element C1, and a diode D1, and the voltage conversion unit 10 may also have an inductive element L1 or a transformer T1 ( Figure 1 not shown). In the voltage conversion unit 10, the switching element Q1 controls the conversion of the input DC voltage into the output DC voltage by conducting or disconnecting.

[0049] As Figure 1 shown, the driver circuit 1 further has a control unit 11 and an output current detection unit 12. Among them, the output current detection unit 12 detects the output current generated when the output DC voltage is applied to the external component 2; the control unit 11 can generate a control signal VG that controls the conduction and cutoff of the switching element Q1.

[0050] Figure 2 FIG. is a schematic diagram of the composition of the control unit 11. As Figure 2 shown, the control unit 11 may have a first control unit 111 and a control signal generation unit 112.

[0051] In this embodiment, the first control unit 111 multiplies the difference between the current value Iled of the output current and the target current value Itg by the gain G, and generates a first control signal D1 according to the value after multiplying by the gain. Among them, the first control unit 111 adjusts the gain G according to the target current value Itg; the control signal generation unit 112 generates the control signal VG for controlling the conduction and cutoff of the switching element Q1 according to the first control signal D1.

[0052] According to this embodiment, the control unit 11 of the driver circuit 1 performs feedback control based on the output current. And in the feedback control, the gain G used in the feedback control is adjusted according to the target current value Itg. Thus, the current instability when the target current value is small can be avoided, and the structure is simple.

[0053] In this embodiment, as Figure 2 shown, the first control unit 111 may include: an output current detection unit 1111, a target current detection unit 1112, a subtractor 1113, a gain unit 1114, and a first calculation unit 1115.

[0054] The output current detection unit 1111 obtains the current value Iled of the output current according to the detection signal of the output current detection unit 11; the target current detection unit 1112 obtains the current value Itg of the target current according to the target current signal, where the target current signal can be obtained by processing an external adjustment signal, and the adjustment signal is, for example, a dimming signal for controlling the brightness of the LED; the subtractor 1113 subtracts Itg from Iled; the gain unit 1114 adjusts the magnitude of the gain G according to Itg, multiplies the calculation result of the subtractor 1113 by the gain G, and outputs the multiplied result; the first calculation unit 1115 generates a first control signal D1 according to the result output by the gain unit 1114, where the first calculation unit 1115 is, for example, a proportional-integral (PI) controller or a proportional-integral-derivative (PID) controller.

[0055] The first control unit 111 performs feedback control to make the current value Iled of the output current approach and finally reach the current value Itg of the target current.

[0056] In this embodiment, the manner in which the gain unit 1114 adjusts the gain G according to the current value Itg of the target current may be, for example: the smaller the target current value Itg, the smaller the gain G. When the target current value is small, the output current is also small, and it is more susceptible to noise, so the signal-to-noise ratio (S / N) is low. In addition, the voltage / current characteristics of external components may also become non-linear. Therefore, the difficulty of negative feedback increases. So, in this embodiment, when the target current value Itg is small, the gain G is also set to be small, which can weaken the intensity of negative feedback and reduce the difficulty of control.

[0057] Figure 3 is a schematic diagram showing the change of the gain with the target current value Itg in the implementation of this application, Figure 4 is another schematic diagram showing the change of the gain with the target current value Itg in the implementation of this application. In Figure 3 and Figure 4In this case, the vertical axis represents the gain G, and the horizontal axis represents the ratio between the target current value Itg and the rated current value Iledtyp of the external component.

[0058] As Figure 3 and Figure 4 shown, when the target current value Itg is in the first interval, the gain G is 0. Thus, negative feedback can be stopped. Among them, in this first interval, the ratio of the target current value Itg to the rated current value Iledtyp of the external component (i.e., Itg / Iledtyp) is in a low ratio range, and this low ratio range is, for example, 0% to 10%, and Iledtyp is a fixed value. In addition, the above numerical range can also be understood as the ratio Itg / Iledtyp of the target current value Itg corresponding to the end point of the first interval to the rated current value Iledtyp of the external component being 0% to 10%, and this end point can be regarded as the maximum value of the target current value Itg in the first interval. As Figure 3 and Figure 4 shown, this first interval can be, for example, the interval from Itg = 0 (i.e., Itg / Iledtyp = 0%) to this end point.

[0059] In this embodiment, in the interval where the gain G is not 0, there is a linear relationship ([[]] Figure 3 shown) or a non-linear relationship ([[]] Figure 4 shown) between the gain G and the target current value Itg.

[0060] Among them, when there is a linear relationship between the gain G and the target current value Itg, smoother dimming can be achieved; when there is a non-linear relationship between the gain G and the target current value Itg, in the case where there are multiple LEDs in the external component, the error with Itg caused by the deviation of the parameters of the circuit constants when the target current value Itg is relatively large can be reduced, so that dimming can be performed without flickering or discomfort when the dimming is variable from light dimming (Itg is relatively large) to deep dimming (Itg is relatively small).

[0061] As Figure 4 shown, in the interval where the gain G is not 0, when there is a non-linear relationship between the gain G and the target current value Itg, when the target current value Itg is in the second interval, the gain G remains unchanged.

[0062] As Figure 4 shown, the ratio Itg / Iledtyp of the target current value Itg corresponding to the starting point of the second interval to the rated current value Iledtyp of the external component is in a medium ratio range, and this medium ratio range is, for example, 20% to 50%, and this starting point can be regarded as the minimum value of the target current value Itg in the second interval. As Figure 4As shown, this second interval can be, for example, the interval from this starting point to Itg = Iledtyp (i.e., Itg / Iledtyp = 100%).

[0063] As Figure 4 shown, the dashed line 401 indicates that when Itg / Iledtyp corresponding to the end point of the first interval is 0% and Itg / Iledtyp corresponding to the starting point of the second interval is 20%, the gain G has a linear relationship with Itg; the dashed line 402 indicates that when Itg / Iledtyp corresponding to the end point of the first interval is 10% and Itg / Iledtyp corresponding to the starting point of the second interval is 50%, the gain G has a linear relationship with Itg.

[0064] In this embodiment, Itg / Iledtyp corresponding to the end point of this first interval and Itg / Iledtyp corresponding to the starting point of the second interval can also be other ranges.

[0065] In this embodiment, Figure 4 shows a case of the non - linear relationship. This embodiment is not limited thereto, and the non - linear relationship can also be other cases.

[0066] Figure 5a is a schematic diagram of the control signal generation unit 112 of this embodiment, Figure 5b is a schematic diagram of each signal in the control signal generation unit 112 of this embodiment.

[0067] As Figure 5a and 5b shown, the control signal generation unit 112 includes: a carrier signal generator 1121 and an AND gate circuit 1122. Among them, the carrier signal generator 1121 generates a carrier CS; the AND gate circuit 1122 can use the first control signal D1 as a drive signal DRV and perform a logical "AND" operation on the drive signal DRV and the carrier CS, thereby outputting a control signal VG.

[0068] As Figure 5b shown, this carrier CS is, for example, a triangular wave signal. In addition, this carrier CS can also be a sine wave signal, etc. This carrier CS has periodicity, and the frequency of this carrier CS is f.

[0069] In this embodiment, as Figure 1 shown, the driver circuit 1 can also include: an input voltage detection unit 13 and an output voltage detection unit 14. The input voltage detection unit 13 detects the input DC voltage; the output voltage detection unit 14 detects the output DC voltage.

[0070] As Figure 2As shown, the control unit 11 also has a second control section 113. The second control section 113 calculates a second control signal D2 based on the first voltage value Vin of the input DC voltage, the second voltage value Vled of the output DC voltage, the target current value Itg, and the circuit parameters of the driver circuit 1.

[0071] As Figure 2 shown, the second control section 113 has: a first voltage value detection section 1131, a second voltage value detection section 1132, and a second calculation unit 1133. Among them, the first voltage value detection section 1131 obtains the first voltage value Vin from the detection result of the input voltage detection unit 13; the second voltage value detection section 1132 obtains the second voltage value Vled from the detection result of the output voltage detection unit 14; the second calculation unit 1133 calculates the second control signal D2.

[0072] In this embodiment, the circuit parameters of the driver circuit used by the second calculation unit 1133 when calculating the second control signal D2 include: the inductance value L of the inductor element L1; and the frequency f of the carrier CS used by the control unit 11 to generate the control signal, where the carrier CS is as Figure 5b shown, and it is generated by Figure 5a the carrier signal generator 1121.

[0073] Thus, the second calculation unit 1133 can calculate the second control signal D2 based on the first voltage value Vin, the second voltage value Vled, the target current value Itg, the inductance value L of the inductor element L1, and the frequency f of the carrier CS. For example, the second calculation unit 1133 can calculate according to the following formula (1):

[0074]

[0075] In this embodiment, as Figure 2 and Figure 5a shown, in the case of having the second control signal D2, the control signal generation section 112 generates a control signal VG according to the result of adding the second control signal D2 and the first control signal D1. For example, the result of adding the second control signal D2 and the first control signal D1 is used as the drive signal DRV, and a logical "AND" operation is performed on the drive signal DRV and the carrier signal CS, thereby outputting the control signal VG.

[0076] In addition, in this embodiment, in the case of replacing the inductor L1 with a transformer T1, the second calculation unit 1133 can replace the inductance value L of the inductor L1 with the inductance value of the primary winding and / or the secondary winding of the transformer T1, and calculate the second control signal D2 using a formula similar to formula (1).

[0077] The second control unit 113 of this embodiment does not rely on the input current value Iled for control and can perform feedforward control. This feedforward control can supplement the feedback control of the first control unit 111. When the target current Itg is small, the accuracy of the feedback control decreases, and thus the gain of the feedback control decreases. At this time, the on and off of the switching element are mainly controlled by the feedforward control of the second control unit 113. Therefore, the accuracy and reliability of the control can be improved.

[0078] Figure 6 is another schematic diagram of the driver circuit according to an embodiment of the present application. As Figure 6 shown, the output current detection unit 12 can be a resistor R1, which is connected in series with an external component, and the output current is detected by the voltage drop across both ends of the resistor R1.

[0079] Figure 7 is another schematic diagram of the driver circuit according to an embodiment of the present application. As Figure 7 shown, the output current detection unit 12 can be a current sensor, which is connected in series with an external component, and the output current is detected by the voltage drop across both ends of the current sensor.

[0080] Figure 8a is another schematic diagram of the driver circuit according to an embodiment of the present application. As Figure 8a shown, the output current detection unit 12 includes: a peak current detection unit 121 and a commutation period detection unit 122.

[0081] Among them, the peak current detection unit 121 detects the maximum value Idpeak of the current flowing through the driver circuit 1; the commutation period detection unit 122 detects the time during which the current exists in the inductor element L1 when the switching element Q1 is turned off.

[0082] Figure 8b is Figure 8a a schematic diagram of the control unit 11 of the driver circuit. As Figure 8b shown, the first control unit 111 of the control unit 11 further has a current calculation unit 1116. The current calculation unit 1116 calculates the current value Iled of the output current according to the detection results of the peak current detection unit 121 and the commutation period detection unit 122. For example, the current calculation unit 1116 can calculate the current value Iled of the output current according to the following formula (2):

[0083]

[0084] Among them, T on represents the time of the high level (causing the switching element Q1 to conduct) of the control signal VG within one cycle; T comIndicates the time during which the current exists in the inductor element L1 while the switching element Q1 is off.

[0085] Figure 8c Is Figure 8a A timing diagram of some signals in the driver circuit of. Among them, VG represents the control signal; Vc represents the voltage at the source of the switching element Q1; Id represents the current flowing to the negative electrode of the voltage input unit; IL represents the current flowing through the inductor element L1; Iled represents the current value of the calculated output current; Ton represents the time when the control signal VG is at a high level (causing the switching element Q1 to conduct) within one cycle; Toff represents the time when the control signal VG is at a low level (causing the switching element Q1 to turn off) within one cycle; T represents the cycle of the control signal VG; Tcom represents the time during which the current exists in the inductor element L1 while the switching element Q1 is off.

[0086] In addition, as Figure 8b shown, the first control unit 111 of the control unit 11 may also have a maximum current detection unit 1117 and a commutation period acquisition unit 1118. Among them, the maximum current detection unit 1117 can obtain Idpeak from the detection result of the peak current detection unit 121, and the commutation period acquisition unit 1118 can obtain Tcom from the detection result of the commutation period detection unit 122. In addition, Figure 8b the first control unit 111 of Figure 2 does not have the output current detection unit 1111 as

[0087] Figure 8d Is for Figure 8a A timing diagram of some signals in the circuit when FF control is introduced into the driver circuit 1 of. Among them, IQ is the current flowing through the switching element Q1, Is is the current flowing through the peak current detection unit 121, and Is = IQ, Ip1 represents the peak value of IQ; IL is the current flowing through the inductor element L1, and Ip2 represents the peak value of IL; ID is the current flowing through the diode D1, and Ip3 represents the peak value of ID. In Figure 8d , the meanings of Ton, Tcom, and Toff are the same as above, and Ton + Tcom + Toff = T.

[0088] Figure 9a Is another schematic diagram of the driver circuit 1. Different from Figure 8a is that Figure 9a the voltage conversion unit 10a of the driver circuit 1 shown in

[0089] Figure 9b Is for Figure 9aA timing diagram of some signals in the circuit when FF control is introduced into the driver circuit 1. Among them, the meanings of the parameters are the same as those in Figure 8d In addition, in Figure 9b IL = Is.

[0090] Figure 10a is another schematic diagram of the driver circuit 1. The difference from Figure 8a is that Figure 10a the voltage conversion unit 10b of the driver circuit 1 shown is a buck-boost chopper circuit.

[0091] Figure 10b is a timing diagram of some signals in the circuit when FF control is introduced into the driver circuit 1 of Figure 10a Among them, the meanings of the parameters are the same as those in Figure 8d In addition, in Figure 10b IL = Is.

[0092] Figure 11 is another schematic diagram of the driver circuit 1. The difference from Figure 9a is that Figure 11 in the voltage conversion unit 10c of the driver circuit 1 shown, the inductor L1 in Figure 9a is replaced by a transformer T1. Thus, the voltage conversion unit 10c becomes an isolated buck-boost chopper circuit.

[0093] Figure 12 is another schematic diagram of the driver circuit 1. The difference from Figure 11 is that Figure 12 an auxiliary coil Laux is added to the driver circuit 1 shown, and the auxiliary coil Laux is coupled with the transformer T1.

[0094] As shown in Figure 12 the driver circuit 1 may also have an auxiliary detection unit 15. The auxiliary detection unit 15 detects at least one of the following values according to the voltage signal in the auxiliary coil Laux: the first voltage value Vin of the input DC voltage; the second voltage value Vled of the output DC voltage; the time Tcom during which the current exists in the inductor element L1 when the switching element Q1 is turned off.

[0095] In addition, when detecting Vin through the auxiliary detection unit 15, the input voltage detection unit 13 may not be provided; when detecting Vled through the auxiliary detection unit 15, the output voltage detection unit 14 may not be provided; when detecting Tcom through the auxiliary detection unit 15, the commutation period detection unit 122 may not be provided.

[0096] Figure 13is another schematic diagram of the driver circuit. Different from Figure 12 , in Figure 13 , a diode D2 and a capacitive element C2 are added. The voltage obtained by the auxiliary coil Laux is rectified and filtered and then provided to the control unit 11 as the operating voltage Vcc of the control unit 11. In addition, in Figure 13 , the second voltage value Vled, the first voltage value Vin, and Tcom are detected by the auxiliary detection unit 15, and the input voltage detection unit 13, the output voltage detection unit 14, and the commutation period detection unit 122 are not provided.

[0097] Figure 14 is Figure 13 a schematic diagram of the control unit 11 of Figure 14 . As shown in Figure 14 , the control unit 11 further has a minimum duty ratio setting unit 114. The minimum duty ratio setting unit 114 sets the duty ratio of the control signal VG to be greater than 0. If the duty ratio of the control signal VG is 0, it will cause the auxiliary coil Laux to be unable to provide the operating voltage Vcc for the control unit 11. Therefore, setting the duty ratio to be greater than 0 can ensure that the operating voltage Vcc is provided for the control unit 11.

[0098] According to the driver circuit of the present application, the gain used in the feedback control is adjusted according to the target current value. Thus, the instability of the current when the target current value is small can be avoided, and the structure is simple; in addition, feedforward control can also be performed on the basis of the feedback control in the driver circuit, thereby improving the accuracy of the control.

[0099] Embodiment 2

[0100] Embodiment 2 of the present application provides a power supply, and this power supply has the driver circuit of Embodiment 1. In Embodiment 2, the same content as that in Embodiment 1 will not be described in detail.

[0101] Figure 15 is a schematic diagram of the power supply 150 of the embodiment of the present application. As shown in Figure 15 , the power supply 150 has a voltage input unit 1500 and a driver circuit 1. Among them, the voltage input unit 1500 inputs a DC voltage to the input terminal of the driver circuit 1; the structure and function of the driver circuit 1 are the same as those in Embodiment 1. In Figure 15 , the driver circuit 1 has the structure of the driver circuit 1 shown in FIG. 8. This embodiment is not limited thereto, and the driver circuit 1 may also be Figure 1 , FIG. 9, FIG. 10, Figure 11 , Figure 12 or Figure 13 shown structure.

[0102] In this embodiment, as shown in Figure 15As shown, the voltage input unit 1500 may include: an AC power supply 1501, and a rectifying and smoothing circuit 1502 connected to the AC power supply 1501. The rectifying and smoothing circuit 1502 can convert the AC voltage output by the AC power supply 1501 into a DC voltage. The rectifying and smoothing circuit 1502 may be, for example, a bridge rectifier.

[0103] Figure 16 is another schematic diagram of the power supply 150 of the embodiment of the present application. Different from Figure 15 in that, Figure 16 uses a power factor correction (PFC) circuit 1503 to replace Figure 15 the rectifying and smoothing circuit 1502. The power factor correction (PFC) circuit 1503 can convert the AC voltage output by the AC power supply 1501 into a DC voltage.

[0104] In this embodiment, the voltage input unit 1500 may also be a DC power supply. For example, in the Figure 1 of the embodiment, Figures 9, 10, Figure 11 , Figure 12 or Figure 13 shown in the driver circuit, a DC voltage is input to the driver by the DC power supply 1504.

[0105] Figure 17 is an actual circuit diagram of the power supply 170 of this embodiment. As Figure 17 shown, in the power supply 170, the AC voltage output by the AC power supply 1701 is rectified by the bridge rectifying circuit 1702. The inductor element L3 detects the current in the inductor element L2 and inputs the detection result to the controller 1705 for zero-crossing detection. The voltage of the resistor R1 is input to the controller 1705 to detect the current flowing through the switching element Q2, that is, to detect the pfc current. The controller 1705 outputs a control signal Vpfc for controlling the conduction and turn-off of the switching element Q2. The resistors R2, R3, and R4 are connected in series, and the voltage signal at the connection point of R3 and R4 is input to the controller 1705 to detect the input DC voltage Vin. The voltage at the connection point of the resistor R5 and the switching element Q1 is input to the controller 1705 to detect the peak current Idpeak.

[0106] The auxiliary coil Laux is coupled to the transformer T1. The capacitor C2 and the diode D2 rectify and filter the voltage of the auxiliary coil Laux, and the rectified and filtered voltage is input to the controller 1705 as the supply voltage Vcc of the controller 1705. The controller 1705 outputs a control signal VG to the switching element Q1 to control the conduction and disconnection of the switching element Q1. The diode D1 and the capacitor C1 rectify and filter the voltage coupled to the secondary winding of T1, and output it as a DC voltage to the external component 2, which is, for example, an LED. The voltage obtained by the auxiliary coil Laux is also directly input to the controller 1705 to detect the output DC voltage Vled and the duration Tcom of the current during the disconnection of the switching element Q1.

[0107] The adjustment unit 1703 generates an adjustment signal for adjusting the target current Iled. The adjustment signal is processed by the processing unit 1704 to generate target current information, and the target current information is input to the controller 1705 to obtain the target current value Itg.

[0108] Figure 17 The controller 1705 in [description] can implement the feedback control and feedforward control functions of the control unit 11 for the switching element Q1 in this application, and can also implement the PFC control function.

[0109] For each component unit of the control unit of the driver circuit described in this embodiment, it can be implemented as a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or any suitable combination thereof for performing the functions described in this application. It can also be implemented as a combination of computing devices, for example, a combination of a DSP and a microprocessor, multiple microprocessors, one or more microprocessors in communication combination with a DSP, or any other such configuration.

[0110] The present application has been described in conjunction with specific embodiments, but those skilled in the art should understand that these descriptions are exemplary and not a limitation on the protection scope of the present application. Those skilled in the art can make various variations and modifications to the present application according to the spirit and principle of the present application, and these variations and modifications are also within the scope of the present application.

Claims

1. A driver circuit having a voltage conversion unit that converts an input DC voltage into an output DC voltage, the voltage conversion unit having a switching element, a capacitive element, and a diode, and the voltage conversion unit further having an inductive element or a transformer, wherein, The switching element controls the conversion of the input DC voltage into the output DC voltage by conducting or disconnecting. The driver circuit further has: An output current detection unit that detects the output current generated when the output DC voltage is applied to an external component. A control unit having a first control section that multiplies the difference between the current value of the output current and the target current value by a gain and generates a first control signal based on the value after multiplying by the gain. The control unit further has a control signal generation section that generates a control signal for controlling the conduction and disconnection of the switching element based on the first control signal. Wherein, the first control section adjusts the gain according to the target current value. The smaller the target current value, the smaller the gain.

2. The driver circuit according to claim 1, wherein, When the target current value is in a first interval, the gain is 0.

3. The driver circuit according to claim 2, wherein, In the first interval, the ratio of the target current value to the rated current value of the external component is in a first ratio range, and the first ratio range is 0% to 10%.

4. The driver circuit according to claim 2, wherein, In the interval where the gain is not 0, the relationship between the gain and the target current value is a linear relationship or a non-linear relationship.

5. The driver circuit according to claim 4, wherein, In the case where the relationship between the gain and the target current value is a non-linear relationship. When the target current value is in a second interval, the gain remains unchanged.

6. The driver circuit according to claim 5, wherein, The ratio of the target current value corresponding to the starting point of the second interval to the rated current value of the external component is in a second ratio range, and the second ratio range is 20% to 50%.

7. The driver circuit according to claim 1, wherein, The driver circuit further includes: An input voltage detection unit that detects the input DC voltage; and An output voltage detection unit that detects the output DC voltage. The control unit further has a second control section that calculates a second control signal based on the first voltage value of the input DC voltage, the second voltage value of the output DC voltage, the target current value, and the circuit parameters of the driver circuit. The control signal generation section generates the control signal based on the result of adding the second control signal and the first control signal.

8. The driver circuit according to claim 7, wherein, The circuit parameters of the driver circuit include: The inductance value of the inductive element, or the inductance value of the primary winding and / or the secondary winding of the transformer; and The carrier frequency used by the control unit to generate the control signal.

9. The driver circuit according to claim 1, wherein, The output current detection unit includes: A resistor or current sensor connected in series with the external component.

10. The driver circuit according to claim 1, wherein, The output current detection unit includes: A peak current detection section that detects the maximum value of the current flowing through the driver circuit; and A commutation period detection section that detects the time during which the current exists in the inductive element during the disconnection period of the switching element. The first control section further has a current calculation unit that calculates the current value of the output current based on the detection results of the peak current detection section and the commutation period detection section.

11. The driver circuit according to claim 1, wherein, The voltage conversion unit is a boost chopper circuit or a buck-boost chopper circuit.

12. The driver circuit according to claim 1, wherein, When the inductive element is replaced by a transformer, the driver circuit further has an auxiliary coil. The control unit has an auxiliary detection unit that detects at least one of the following values based on the voltage signal in the auxiliary coil: a first voltage value of the input DC voltage; a second voltage value of the output DC voltage; and the time during which current exists in the inductive element while the switching element is off.

13. The driver circuit according to claim 12, wherein, The auxiliary coil also provides an operating voltage for the control unit.

14. The driver circuit according to claim 13, wherein, The duty cycle of the control signal is greater than 0.

15. A power supply having a voltage input unit and the driver circuit according to any one of claims 1-14, wherein, The voltage input unit inputs a DC voltage to the input terminal of the driver circuit, The voltage input unit includes: a DC power supply; or an AC power supply and a rectifying and smoothing circuit or a power factor correction circuit connected to the AC power supply.

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