Linear driving circuit

Abstract

The invention provides a linear driving circuit comprising a driving circuit body which comprises a first switch, a second switch, a third switch, a fourth switch, a first energy storage capacitor and a second energy storage capacitor; the control unit is in communication connection with the driving circuit body and used for controlling the third switch and the fourth switch to be periodically switched off or switched on so that the driving circuit body can operate according to a preset operation rule, and the first switch, the first energy storage capacitor, the second energy storage capacitor, the second switch and the power supply are sequentially connected in series to form a closed loop. The third switch is connected to the two ends of a series body formed by the first switch and the first energy storage capacitor in parallel, one end of the fourth switch is coupled to the connection point of the first energy storage capacitor and the second energy storage capacitor, the other end of the fourth switch is coupled to the intersection point of the second switch and the power supply, and the first load is connected to the first output node and the third output node. The second load is connected to the second output node and the third output node.

Description

Technical Field

[0001] The invention belongs to the field of power electronics, and in particular relates to a linear drive circuit. Background Art

[0002] like Fig.10 As shown, a linear drive circuit 300 for driving LED light emission is powered by a power supply having a pulsating voltage ripple, such as a DC power supply generated by AC mains rectification, to drive a load module 400 composed of loads L01, L02 and L03. The linear drive circuit 300 includes three current sources I001, I002 and I003 with different conduction priorities, the conduction priority of I003 is greater than that of I002, and the conduction priority of I002 is greater than that of I001. The loads L01, L02 and L03 are connected in parallel with energy storage capacitors C01, C02 and C03 respectively to reduce the current ripple of the loads L01, L02 and L03 and reduce the light emission fluctuation (stroboscopic). Diodes D01 and D02 are used to block the reverse discharge of energy storage capacitors C02 and C03 to I001 and I002 respectively. When the power supply voltage VIN(t) is less than the voltage across C01, I001, I002 and I003 cannot be turned on, and the currents of L01, L02 and L03 are maintained by C01, C02 and C03 respectively; when the power supply voltage is greater than the voltage across C01 but less than the sum of the voltages across C01 and C02, the parallel body composed of C01 and L101 is powered, and the power supply current is limited by I001, C02 maintains the current of L02, and C03 maintains the current of L03; when the power supply voltage VIN(t) is greater than the voltage across C01 and C02, the parallel body composed of C01 and L101 is powered, and the power supply current is limited by I001, C02 maintains the current of L02, and C03 maintains the current of L03; When the supply voltage VIN(t) is greater than the sum of the voltages of C01, C02 and C03, the parallel body composed of C01 and L01, and the parallel body composed of C02 and L02 are all powered, the supply current is limited by I002, I001 is cut off, and C03 maintains the current of L03; when the supply voltage VIN(t) is greater than the sum of the voltages of C01, C02 and C03, the parallel body composed of C01 and L01, the parallel body composed of C02 and L02, and the parallel body composed of C03 and L03 are all powered, the supply current is limited by I003, and I001 and I002 are both cut off.

[0003] In the above-mentioned driving circuit, the number of parallel bodies of energy storage capacitors and loads, and the number of current sources are all 3, which adapts to a wider power supply voltage range. When the DC power supply is generated by rectifying the AC mains, the current conduction angle of the AC mains is increased, the power factor is improved and the current harmonics are reduced. However, the disadvantages are: 1) The currents of loads L01, L02 and L03 (smaller in sequence) are inconsistent, which is easy to be perceived by the naked eye as uneven light emission for lighting devices with a large light-emitting area, such as panel lights; 2) There are six connecting wires between the load 101 and the output end of the driving circuit 100, namely, the two ends of C01, the two ends of C02 and the two ends of C03, which increases the cost and complexity in practical applications. In some lighting devices, such as lighting fixtures with transparent or translucent structural parts, the increase in the number or size of wires will affect the beauty of the lamp. Therefore, a linear driving solution is needed that reduces the inconsistency of load current and has fewer connecting wires between the loads. Summary of the invention

[0004] The present invention is made to solve the above-mentioned problem, and its object is to provide a linear drive circuit.

[0005] In order to achieve the above object, the present invention adopts the following scheme:

[0006] The present invention provides a linear drive circuit, which is connected to a power supply that provides a periodic pulsating voltage as a power supply voltage, and is used to drive a load module composed of a first load and a second load with different conduction voltage drops, and has the following characteristics: a drive circuit body, including a first switch, a second switch, a third switch, a fourth switch, a first energy storage capacitor and a second energy storage capacitor; and a control unit, which is communicatively connected to the drive circuit body and is used to control the first switch, the second switch, the third switch and the fourth switch to be periodically turned off or turned on so that the drive circuit body operates according to a preset operation rule, wherein the first switch, the first energy storage capacitor, the second energy storage capacitor, The second switch and the power supply are connected in series in sequence to form a closed loop, the third switch is connected in parallel to the two ends of the series body formed by the first switch and the first energy storage capacitor, one end of the fourth switch is coupled to the connection point of the first energy storage capacitor and the second energy storage capacitor, and the other end is coupled to the intersection of the second switch and the power supply, the intersection of the first energy storage capacitor and the first switch is set as the first output node, the intersection of the second energy storage capacitor and the second switch is set as the second output node, the intersection of the first energy storage capacitor and the second energy storage capacitor is set as the third output node, the first load is connected to the first output node and the third output node, and the second load is connected to the second output node and the third output node.

[0007] In the linear drive circuit provided by the present invention, it can also have the following characteristics: wherein, when the conduction voltage drop of the first load is greater than the conduction voltage drop of the second load, in response to the power supply voltage being less than the conduction voltage drop of the second load, the first switch and the second switch are turned off, the third switch and the fourth switch are turned on, and the drive circuit body forms a first loop; in response to the power supply voltage being greater than the conduction voltage drop of the second load but less than the conduction voltage drop of the first load, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the drive circuit body forms a second loop; in response to the power supply voltage being greater than the conduction voltage drop of the first load but less than the sum of the conduction voltage drops of the first load and the second load, the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, and the drive circuit body forms a third loop; in response to the power supply voltage being greater than the sum of the conduction voltage drops of the first load and the second load, the first switch and the second switch are turned on, the third switch and the fourth switch are turned off, and the drive circuit body forms a main loop; the preset operation rule is: the drive circuit body operates in the first loop, the second loop, the third loop, the main loop, the third loop, the second loop, and the first loop in sequence, or the drive circuit body operates in the second loop, the third loop, and the third loop in sequence. , main circuit, third circuit, second circuit; when the conduction voltage drop of the first load is less than the conduction voltage drop of the second load, in response to the power supply voltage being less than the conduction voltage drop of the first load, the first switch and the second switch are turned off, the third switch and the fourth switch are turned on, and the driving circuit body forms a first circuit; in response to the power supply voltage being greater than the conduction voltage drop of the first load but less than the conduction voltage drop of the second load, the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, and the driving circuit body forms a third circuit; in response to the power supply voltage being greater than the conduction voltage drop of the second load but less than the conduction voltage drop of the first load and the second load The sum of the conduction voltage drops of the first load and the second load is calculated, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the driving circuit body forms a second loop. In response to the supply voltage being greater than the sum of the conduction voltage drops of the first load and the second load, the first switch and the second switch are turned on, the third switch and the fourth switch are turned off, and the driving circuit body forms a main loop. The preset operating rule is: the driving circuit body operates in the first loop, the third loop, the second loop, the main loop, the second loop, the third loop, and the first loop in sequence, or the driving circuit body operates in the third loop, the second loop, the main loop, the second loop, and the third loop in sequence.

[0008] The linear drive circuit provided by the present invention may also have the following feature: wherein the fourth switch is configured as a switchable current source as the first current source.

[0009] The linear drive circuit provided by the present invention may also have the following feature: wherein the drive circuit body further includes a second current source, and the second current source is connected in series to the second switch.

[0010] The linear drive circuit provided by the present invention may also have the following feature: the conduction priority of the second current source is configured to be higher than the conduction priority of the first current source.

[0011] The linear drive circuit provided by the present invention may also have the following characteristics: in response to the difference between the voltage across the first current source and the voltage across the first energy storage capacitor being greater than a first threshold value, the control unit controls the third switch to be cut off; in response to the voltage across the first current source being less than a second threshold value, the control unit controls the third switch to be turned on.

[0012] The linear drive circuit provided by the present invention may also have the following feature: wherein the first threshold value is greater than the second threshold value.

[0013] The linear drive circuit provided by the present invention may also have the following characteristics: wherein the supply voltage is an AC rectified voltage, and within each AC rectified voltage cycle, the control unit controls the sum of the conduction currents of the first current source and the second current source to be positively correlated with the AC rectified voltage at least within a portion of the time period.

[0014] The linear drive circuit provided by the present invention may also have the following feature: wherein the first switch and the second switch are configured as a first switch diode and a second switch diode respectively.

[0015] The linear drive circuit provided by the present invention may also have the following characteristics: wherein the first load and the second load are both LEDs, and a resistor or a current source is connected in series to the LED.

[0016] Functions and Effects of the Invention

[0017] According to the linear drive circuit involved in the present invention, because it has a drive circuit body and a control unit, the drive circuit body includes a first switch, a second switch, a third switch, a fourth switch, a first energy storage capacitor and a second energy storage capacitor, the control unit is connected to the drive circuit body in communication, and can control the first switch, the second switch, the third switch and the fourth switch to be periodically turned off or turned on so that the drive circuit body operates according to a preset operation rule, the first switch, the first energy storage capacitor, the second energy storage capacitor, the second switch and the power supply are connected in series in sequence to form a closed loop, the third switch is connected in parallel to the two ends of the series body composed of the first switch and the first energy storage capacitor, one end of the fourth switch is coupled to the connection point of the first energy storage capacitor and the second energy storage capacitor, and the other end is coupled to the second switch The intersection of the first energy storage capacitor and the first switch is set as the first output node, the intersection of the second energy storage capacitor and the second switch is set as the second output node, the intersection of the first energy storage capacitor and the second energy storage capacitor is set as the third output node, the first load is connected to the first output node and the third output node, and the second load is connected to the second output node and the third output node. Therefore, when the number of loads is two, the number of connecting lines between the linear drive circuit and the load is 3, which reduces the number of connecting lines; and the two loads are alternately turned on, so that the current difference between the two loads is smaller. When the load is an LED, the light emitting fluctuation of the LED is smaller, or the capacity of the energy storage capacitor is reduced under the premise of satisfying the light emitting fluctuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 is a circuit diagram of a linear drive circuit in an embodiment of the present invention;

[0019] Figure 2 is a circuit diagram of a linear drive circuit in an embodiment of the present invention in a first loop operation state;

[0020] Figure 3 is a circuit diagram of a linear drive circuit in a second loop operation state in an embodiment of the present invention; and

[0021] Figure 4 is a circuit diagram of a linear drive circuit in a third loop operation state in an embodiment of the present invention;

[0022] Figure 5 is a circuit diagram of a linear drive circuit in a main loop operation state in an embodiment of the present invention;

[0023] Figure 6 is a working waveform diagram of the power supply voltage in an embodiment of the present invention;

[0024] Figure 7 is a working waveform diagram of the power supply voltage in an embodiment of the present invention;

[0025] Figure 8 is a circuit diagram of a linear drive circuit in a first variation of the present invention;

[0026] Fig. 9 is a circuit diagram of a linear drive circuit in a second variation of the present invention; and

[0027] Fig.10 It is a circuit diagram of a linear driving circuit used to drive an LED to emit light in the prior art. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments and drawings.

[0029] <Example>

[0030] like Figure 1 As shown, in this embodiment, the linear driving circuit 100 is connected to a power supply VIN that provides a periodic pulsating voltage as a power supply voltage, and is used to drive a load module 200 composed of a first load L1 and a second load L2 having different conduction voltage drops. The linear driving circuit 100 includes a driving circuit body 10 and a control unit (not shown in the figure).

[0031] like Figure 1 As shown, the driving circuit body 10 includes a first switch S1, a second switch S2, a third switch S3, a fourth switch S4, a first energy storage capacitor C1 and a second energy storage capacitor C2.

[0032] The first switch S1 , the first energy storage capacitor C1 , the second energy storage capacitor C2 , the second switch S2 , and the power supply VIN are sequentially connected in series to form a closed loop.

[0033] The third switch S3 is connected in parallel to two ends of a series body formed by the first switch S1 and the first energy storage capacitor C.

[0034] One end of the fourth switch S4 is coupled to the connection point between the first energy storage capacitor C1 and the second energy storage capacitor C2 , and the other end of the fourth switch S4 is coupled to the intersection of the second switch S2 and the power supply VIN.

[0035] The intersection of the first energy storage capacitor C1 and the first switch S1 is set as the first output node, the intersection of the second energy storage capacitor C2 and the second switch S2 is set as the second output node, and the intersection of the first energy storage capacitor C1 and the second energy storage capacitor C2 is set as the third output node; the first output node, the second output node and the third output node are used to connect an external load.

[0036] The first load L1 is connected to the first output node and the third output node, and the second load L2 is connected to the second output node and the third output node.

[0037] The control unit is connected to the driving circuit body 10 for controlling the first switch S1, the second switch S2, the third switch S3 and the fourth switch S4 to operate as follows: Figures 2 to 5 The circuit shown is periodically turned off or on, so that the driving circuit body 10 operates according to a preset operating rule.

[0038] The following takes the example that both the first load L1 and the second load L2 are LEDs and the conduction voltage drop V1 of the first load L1 is greater than the conduction voltage drop V2 of the second load L2 to explain the operation state of the driving circuit body 10 .

[0039] The power supply VIN is an AC rectifier power supply, and the output power supply voltage thereof is a periodic pulsating voltage, which is represented by VIN(t), where t is the pulsating period of the AC rectifier power supply.

[0040] like Figure 2 As shown, in response to the supply voltage VIN(t) being less than the conduction voltage drop V2 of the second load L2, the first switch S1 and the second switch S2 are turned off, the third switch S3 and the fourth switch S4 are turned on, and the driving circuit body 10 forms a first loop.

[0041] The first switch S1 is turned off, blocking the parallel body formed by the first energy storage capacitor C1 and the first load L1 connected in parallel therewith from discharging to the outside; the second switch S2 is turned off, blocking the parallel body formed by the second energy storage capacitor C2 and the second load L2 connected in parallel therewith from discharging to the outside. The first load L1 is maintained by the first energy storage capacitor C1, and the second load L2 is maintained by the second energy storage capacitor C2. In this state, if any one or all of the third switch S3 and the fourth switch S4 are turned off, the linear drive circuit 100 does not draw current from the power supply VIN, which can be referred to Figure 7 If the third switch S3 and the fourth switch S4 are both turned on, the linear drive circuit 100 draws current from the power supply VIN, which can be referred to Figure 6 The waveform of the T0-T1 or T6-T7 time period.

[0042] Specifically, when the third switch S3 and the fourth switch S4 are both closed, the current output by the power supply VIN returns to GND (ground or common ground) via the third switch S3 and the fourth switch S4, and the driving circuit body 10 forms a first loop. From the perspective of energy conversion, the current of the first loop reduces the energy conversion efficiency of the linear driving circuit 100. However, when the power supply voltage is generated by AC rectification, from the perspective of the AC current waveform, there is still current conduction near the sine wave crossover point, which is beneficial to improving current harmonic distortion, and is also beneficial for power supply scenarios with thyristor dimming devices connected in series in the AC power supply line, because it provides a maintenance current for the thyristor dimming device. In specific implementation, it can be determined whether to control the first loop to be turned on according to actual needs.

[0043] like Figure 3 As shown, in response to the supply voltage VIN(t) being greater than the conduction voltage drop V2 of the second load L2 but less than the conduction voltage drop V1 of the first load L1, the first switch S1 and the fourth switch S4 are turned off, the second switch S2 and the third switch S3 are turned on, and the drive circuit body 10 forms a second loop.

[0044] Specifically, the first load L1 is maintained by the first energy storage capacitor C1; the power supply VIN supplies power to the parallel body formed by the second energy storage capacitor C2 and the second load L2, which can be referred to Figure 3 A and / or Figure 3 Waveform of the T1-T2 or T5-T6 time period in B.

[0045] like Figure 4 As shown, in response to the power supply voltage VIN(t) being greater than the on-state voltage drop V1 of the first load L1 but less than the sum of the on-state voltage drops V1+V2 of the first load L1 and the second load L2, the first switch S1 and the fourth switch S4 are turned on, the second switch S2 and the third switch S3 are turned off, and the drive circuit body 10 forms a third loop.

[0046] Specifically, the second load L2 maintains the current by the second energy storage capacitor C2; the power supply VIN supplies power to the parallel body formed by the first energy storage capacitor C1 and the first load L1, which can be referred to Figure 6 and / or Figure 7 The waveform of the T2-T3 or T4-T5 time period.

[0047] like Figure 5 As shown, in response to the supply voltage VIN(t) being greater than the sum of the conduction voltage drops V1+V2 of the first load L1 and the second load L2, the first switch S1 and the second switch S2 are turned on, the third switch S3 and the fourth switch S4 are turned off, and the drive circuit body 10 forms a main loop.

[0048] Specifically, the power supply VIN supplies power to the first energy storage capacitor C1 and the first load L1 connected in parallel therewith, and the second energy storage capacitor C2 and the second load L2 connected in parallel therewith. Figure 6 and / or Figure 7 The waveform of the T3-T4 time period.

[0049] Under the premise that the conduction voltage drop V1 of the first load L1 is greater than the conduction voltage drop V2 of the second load L2, corresponding to the 0-180 degree interval of the AC phase, the above preset operation rule is: the drive circuit body 10 operates in the first loop, the second loop, the third loop, the main loop, the third loop, the second loop, and the first loop in sequence. Of course, as mentioned above, the first loop can be configured as to whether it is turned on or not as required. In the case where the first loop is not turned on, the preset operation rule is: the drive circuit body 10 operates in the second loop, the third loop, the main loop, the third loop, and the second loop in sequence.

[0050] Functions and Effects of the Embodiments

[0051] According to the linear drive circuit involved in this embodiment, because it has a drive circuit body and a control unit, the drive circuit body includes a first switch, a second switch, a third switch, a fourth switch, a first energy storage capacitor and a second energy storage capacitor, the control unit is connected to the drive circuit body in communication, and can control the first switch, the second switch, the third switch and the fourth switch to be periodically turned off or turned on so that the drive circuit body operates according to a preset operation rule, the first switch, the first energy storage capacitor, the second energy storage capacitor, the second switch and the power supply are connected in series in sequence to form a closed loop, the third switch is connected in parallel to the two ends of the series body composed of the first switch and the first energy storage capacitor, one end of the fourth switch is coupled to the connection point of the first energy storage capacitor and the second energy storage capacitor, and the other end is coupled to the second switch The intersection of the first energy storage capacitor and the first switch is set as the first output node, the intersection of the second energy storage capacitor and the second switch is set as the second output node, the intersection of the first energy storage capacitor and the second energy storage capacitor is set as the third output node, the first load is connected to the first output node and the third output node, and the second load is connected to the second output node and the third output node. Therefore, in this embodiment, when the number of loads is two, the number of connecting lines between the linear drive circuit and the load is 3, which reduces the number of connecting lines; and, the two loads are alternately turned on, so that the current difference between the two loads is smaller. When the load is an LED, the light emitting fluctuation of the LED is smaller, or the capacity of the energy storage capacitor is reduced under the premise of satisfying the light emitting fluctuation.

[0052] <Modification 1>

[0053] This modification example 1 is a further improvement of the embodiment. The same symbols are given to the same components as in the embodiment, and the same descriptions are omitted.

[0054] Compared with the driving circuit body 10 in the embodiment, Figure 8 As shown, in this first variation, the difference of the driving circuit body 10A in the linear driving circuit 100A is that: the fourth switch S4 is configured as a switchable current source as the first current source I01; and it also includes a second current source I02, which is connected in series between the second switch S2 and the power supply VIN.

[0055] In this variation 1, the conduction priority of the second current source I02 is configured to be higher than the conduction priority of the first current source I01, that is, 1) when the voltage across the second current source I02 is sufficient, the second current source I02 is conducted according to the current specified by the control unit, and the first current source I01 is cut off (turned off); 2) when the voltage across the second current source I02 is insufficient and the voltage across the first current source I01 is greater than zero, the first current source I01 is conducted. "Zero" here can also be understood as a positive value close to zero in the field of engineering technology.

[0056] In response to the difference between the voltage across the first current source I01 and the voltage across the first energy storage capacitor C1 being greater than the first threshold value, the control unit controls the third switch S3 to be turned off; in response to the voltage across the first current source I01 being less than the second threshold value, the control unit controls the third switch S3 to be turned on. The first threshold value is greater than the second threshold value to prevent the control unit from controlling the third switch S3 to be turned on or off and causing undesirable repetition.

[0057] In each AC rectified voltage cycle, the control unit controls the sum of the conduction currents of the first current source I01 and the second current source I02 to be positively correlated with the AC rectified voltage at least in a portion of the time period, so as to obtain a higher power factor and lower current harmonics. The "positive correlation" here means that when the instantaneous value of the AC rectified voltage is larger, the first current source I01 and / or the second current source I02 draws a current IIN(t) of a larger instantaneous value from the power supply VIN, and vice versa.

[0058] In this first variation, since the fourth switch is configured as a switchable current source as the first current source, a second current source is connected in series between the second switch S2 and the power supply VIN, which can effectively suppress the current ripple and fluctuation of the load.

[0059] <Modification 2>

[0060] This variant example 2 is a further improvement of the variant example 1. The same symbols are given to the same components as those in the variant example 1, and the same descriptions are omitted.

[0061] Compared with the driving circuit body 10A in the first modification, Fig. 9As shown, in the second variation, the difference of the driving circuit body 10B in the linear driving circuit 100B is that the first switch S1 and the second switch S2 are configured as a first switching diode and a second switching diode respectively.

[0062] In the second variation, since the first switch and the second switch are configured as a first switch diode and a second switch diode respectively, compared with ordinary switches, they have the advantages of small size, long life and high reliability.

[0063] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

[0064] For example, in the above embodiment, the on-state voltage drop of the first load is greater than the on-state voltage drop of the second load. However, in the present invention, the on-state voltage drop of the first load may also be less than the on-state voltage drop of the second load. In this case, in response to the power supply voltage being less than the on-state voltage drop of the first load, the first switch and the second switch are turned off, the third switch and the fourth switch are turned on, and the driving circuit body forms a first loop; in response to the power supply voltage being greater than the on-state voltage drop of the first load but less than the on-state voltage drop of the second load, the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, and the driving circuit body forms a third loop; in response to the power supply voltage being greater than the on-state voltage drop of the second load but less than the sum of the on-state voltage drops of the first load and the second load, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the driving circuit body forms a third loop. The switch is turned on, and the driving circuit body forms a second loop; in response to the power supply voltage being greater than the sum of the on-state voltage drops of the first load and the second load, the first switch and the second switch are turned on, and the third switch and the fourth switch are turned off, and the driving circuit body forms a main loop. In this way, under the premise that the on-state voltage drop of the first load is less than the on-state voltage drop V2 of the second load, corresponding to the 0-180 degree interval of the AC phase, the preset operating rules are: the driving circuit body operates in the first loop, the third loop, the second loop, the main loop, the second loop, the third loop, and the first loop in sequence, or the driving circuit body operates in the third loop, the second loop, the main loop, the second loop, and the third loop in sequence.

[0065] For another example, in the present invention, the positions of the second diode and the second current source in the above-mentioned variation 2 may be interchanged, which can also achieve the effect of limiting the load current.

[0066] For another example, in the present invention, a current source may be connected in series to one or more of the first switch S1, the third switch S3, the output VIN(t) or GND of the power supply to achieve the effect of limiting the load current.

[0067] For another example, when the load is an LED, a resistor or a current source may be connected in series with the LED to suppress the current ripple and light emission fluctuation of the LED.

Claims

1. A linear drive circuit, connected to a power supply that provides a periodic pulsating voltage as a power supply voltage, for driving a load module consisting of a first load and a second load with different conduction voltage drops, characterized in that: include: The driving circuit body comprises a first switch, a second switch, a third switch, a fourth switch, a first energy storage capacitor and a second energy storage capacitor; as well as a control unit, which is in communication with the driving circuit body and is used to control the first switch, the second switch, the third switch and the fourth switch to be periodically turned off or turned on so that the driving circuit body operates according to a preset operation rule, The first switch, the first energy storage capacitor, the second energy storage capacitor, the second switch and the power supply are connected in series in sequence to form a closed loop. The third switch is connected in parallel to two ends of a series body formed by the first switch and the first energy storage capacitor. One end of the fourth switch is coupled to the connection point of the first energy storage capacitor and the second energy storage capacitor, and the other end is coupled to the intersection of the second switch and the power supply. The intersection point of the first energy storage capacitor and the first switch is set as a first output node, The intersection point of the second energy storage capacitor and the second switch is set as a second output node, The intersection point of the first energy storage capacitor and the second energy storage capacitor is set as the third output node, The first load is connected to the first output node and the third output node, The second load is connected to the second output node and the third output node.

2. The linear drive circuit according to claim 1, characterized in that: in, When the on-state voltage drop of the first load is greater than the on-state voltage drop of the second load, in response to the supply voltage being less than the on-state voltage drop of the second load, the first switch and the second switch are turned off, the third switch and the fourth switch are turned on, and the driving circuit body forms a first loop. In response to the supply voltage being greater than the conduction voltage drop of the second load but less than the conduction voltage drop of the first load, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the drive circuit body forms a second loop. In response to the supply voltage being greater than the conduction voltage drop of the first load but less than the sum of the conduction voltage drops of the first load and the second load, the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, and the drive circuit body forms a third loop. In response to the supply voltage being greater than the sum of the conduction voltage drops of the first load and the second load, the first switch and the second switch are turned on, the third switch and the fourth switch are turned off, and the drive circuit body forms a main loop. The preset operation rule is: the driving circuit body operates in the first loop, the second loop, the third loop, the main loop, the third loop, the second loop, and the first loop in sequence, or the driving circuit body operates in the second loop, the third loop, the main loop, the third loop, and the second loop in sequence; When the on-state voltage drop of the first load is less than the on-state voltage drop of the second load, in response to the supply voltage being less than the on-state voltage drop of the first load, the first switch and the second switch are turned off, the third switch and the fourth switch are turned on, and the driving circuit body forms the first loop. In response to the supply voltage being greater than the on-state voltage drop of the first load but less than the on-state voltage drop of the second load, the first switch and the fourth switch are turned on, the second switch and the third switch are turned off, and the drive circuit body forms the third loop. In response to the supply voltage being greater than the conduction voltage drop of the second load but less than the sum of the conduction voltage drops of the first load and the second load, the first switch and the fourth switch are turned off, the second switch and the third switch are turned on, and the drive circuit body forms the second loop. In response to the supply voltage being greater than the sum of the conduction voltage drops of the first load and the second load, the first switch and the second switch are turned on, the third switch and the fourth switch are turned off, and the drive circuit body forms the main loop. The preset operation rule is: the drive circuit body operates in the first loop, the third loop, the second loop, the main loop, the second loop, the third loop, and the first loop in sequence, or the drive circuit body operates in the third loop, the second loop, the main loop, the second loop, and the third loop in sequence.

3. The linear drive circuit according to claim 1, characterized in that: in, The fourth switch is configured as a switchable current source as a first current source.

4. The linear drive circuit according to claim 3, characterized in that: in, The driving circuit body further includes a second current source, which is connected in series to the second switch.

5. The linear drive circuit according to claim 4, characterized in that: in, The conduction priority of the second current source is configured to be higher than the conduction priority of the first current source.

6. The linear drive circuit according to claim 3, characterized in that: in, In response to the difference between the voltage across the first current source and the voltage across the first energy storage capacitor being greater than a first threshold value, the control unit controls the third switch to be turned off, In response to the voltage across the first current source being less than a second threshold value, the control unit controls the third switch to be turned on.

7. The linear drive circuit according to claim 6, characterized in that: in, The first threshold value is greater than the second threshold value.

8. The linear drive circuit according to claim 1, characterized in that: in, The supply voltage is an AC rectified voltage. In each cycle of the AC rectified voltage, the control unit controls the sum of the conduction currents of the first current source and the second current source to be positively correlated with the AC rectified voltage in at least a portion of the time period.

9. The linear drive circuit according to claim 1, characterized in that: in, The first switch and the second switch are configured as a first switching diode and a second switching diode, respectively.

10. The linear drive circuit according to claim 1, characterized in that: in, The first load and the second load are both LEDs, A resistor or a current source is connected in series with the LED.

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