Bridge power supply circuit

Abstract

A bridge power circuit is provided, including a first triode, a second triode, a driving transformer, and a triode control circuit, wherein a resonant current on a first winding of the driving transformer is used to provide driving current for the first triode and the second triode, a second winding of the driving transformer is connected between a base and an emitter of the first triode, a third winding of the driving transformer is connected between a base and an emitter of the second triode, the triode control circuit is configured to: based on an output feedback signal representing an output current or an output voltage of the bridge power circuit, control one of the first triode and the second triode to change from a conducting state to a non-conducting state; and when a commutation of the resonant current is detected, control the other of the first triode and the second triode to change from the non-conducting state to the conducting state.

Description

Technical Field

[0001] This invention relates to the field of circuits, and more specifically to a bridge power supply circuit. Background Technology

[0002] Bridge power supply circuits (e.g., half-bridge or full-bridge power supply circuits) are a common switching power supply topology, popular due to their high switching efficiency. Typically, bridge power supply circuits use metal-oxide-semiconductor field-effect transistors (MOSFETs) as switches, offering advantages such as simple control and high reliability. However, because MOSFETs are relatively expensive, bridge power supply circuits using MOSFETs as switches have a higher system cost.

[0003] Compared to MOSFETs, transistors have a significant cost advantage, but because transistors require a large drive current, they place higher demands on the driver and experience greater drive losses. Figure 1 A circuit diagram of a conventional electronic ballast 100 using a transistor as a switch is shown. Figure 1 In the electronic ballast 100 shown, once the transistor is turned on, the resonant circuit provides a driving current to the transistor through the transformer winding, causing the transistor to generate self-excited oscillation according to the inherent frequency of the resonant circuit. Figure 1 While the transistor driving scheme shown solves the problem of transistor drive current, the transistor's switching frequency can only be kept consistent with the resonant circuit's natural frequency and cannot be adjusted according to actual needs. In switching power supply circuits, however, the transistor's switching frequency often needs to be adjusted based on factors such as deviations in electrical component parameters and load conditions.

[0004] Therefore, a transistor driving scheme for bridge power supply circuits is needed to solve the transistor driving problem, improve transistor driving efficiency, and reduce system cost. Summary of the Invention

[0005] According to an embodiment of the present invention, a bridge power supply circuit includes a first transistor, a second transistor, a drive transformer, and a transistor control circuit. The resonant current on the first winding of the drive transformer is used to provide drive current for the first and second transistors. The second winding of the drive transformer is connected between the base and emitter of the first transistor, and the third winding of the drive transformer is connected between the base and emitter of the second transistor. The transistor control circuit is configured to: control one of the first and second transistors to change from an on state to an off state based on an output feedback signal characterizing the output current or output voltage of the bridge power supply circuit; and control the other of the first and second transistors to change from an off state to an on state when a commutation of the resonant current is detected. Attached Figure Description

[0006] The invention can be better understood from the following description of specific embodiments of the invention in conjunction with the accompanying drawings, wherein:

[0007] Figure 1 The circuit diagram shows a traditional bridge power supply circuit that uses transistors as switches.

[0008] Figure 2 A circuit diagram of a bridge power supply circuit according to an embodiment of the present invention is shown.

[0009] Figure 3 It shows Figure 2 The circuit diagram shown is of the transistor drive control circuit in the control chip.

[0010] Figure 4 Showing with Figure 3 The timing diagram of multiple signals related to the transistor drive control circuit is shown.

[0011] Figure 5 It shows Figure 2 The circuit diagram shown is of the current commutation detection circuit in the control chip.

[0012] Figure 6 It shows the relationship with Figure 5 The timing diagram of multiple signals related to the current commutation detection circuit is shown.

[0013] Figure 7 A circuit diagram of a bridge power supply circuit according to another embodiment of the present invention is shown.

[0014] Figure 8 It shows Figure 7 The circuit diagram shown is of the current commutation detection circuit in the control chip.

[0015] Figure 9 Showing with Figure 8 The timing diagram of multiple signals related to the current commutation detection circuit is shown.

[0016] Figure 10 It shows the relationship with Figure 3 The timing diagram of multiple signals related to the transistor drive control circuit is shown. Detailed Implementation

[0017] The features and exemplary embodiments of various aspects of the present invention will now be described in detail. Numerous specific details are set forth in the following detailed description to provide a thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention may be practiced without requiring some of these specific details. The following description of embodiments is merely intended to provide a better understanding of the invention by illustrating examples of the invention. The invention is by no means limited to any specific configurations and algorithms presented below, but covers any modifications, substitutions, and improvements to elements, components, and algorithms without departing from the spirit of the invention. Well-known structures and techniques are not shown in the drawings and the following description in order to avoid unnecessarily obscuring the invention.

[0018] In view of the above, a bridge power supply circuit according to an embodiment of the present invention is proposed, wherein the transistor driving scheme enables the transistor to be turned on and off at a desired switching frequency, which greatly reduces the driving current that the control chip (i.e., the transistor control circuit) used to control the turn-on and turn-off of the transistor needs to provide to the transistor, improves the switching efficiency of the transistor, and significantly reduces the system cost.

[0019] Figure 2 An example circuit diagram of a bridge power supply circuit 200 according to an embodiment of the present invention is shown. Figure 2 In the bridge power supply circuit 200 shown, C1 is the bus capacitor, U1 is the control chip for controlling the on and off of transistors Q1 and Q2, D1, D2, D3, and D4 are freewheeling diodes, W1 is the drive transformer for providing drive current to transistors Q1 and Q2 (W1a, W1b, and W1c are three different windings of the drive transformer W1, with their corresponding terminals pointing in the figure), T1 is the transformer, C2 is the resonant capacitor, and C3 is the output filter capacitor. The bases and emitters of transistors Q1 and Q2 are connected to the corresponding windings of the drive transformer W1, and also to the corresponding control pins of the control chip U1. The control chip U1 can detect the operating state of the system load RL through one or more methods such as primary-side sampling, secondary-side sampling, voltage sampling, and current sampling, and control the on and off of transistors Q1 and Q2 according to the current operating state of the system, thereby controlling the system's operating frequency and adjusting the operating state of the system load RL.

[0020] In other words, in Figure 2In the bridge power supply circuit 200 shown, the resonant current ILr on the winding W1a of the drive transformer W1 is used to provide drive current for transistors Q1 and Q2. The winding W1b of the drive transformer W1 is connected between the base and emitter of transistor Q1, and the winding W1c of the drive transformer W1 is connected between the base and emitter of transistor Q2. The control chip U1 can be configured to control one of transistors Q1 and Q2 from the on state to the off state based on the output feedback signal FB (not shown in the figure) characterizing the output current or output voltage of the bridge power supply circuit 200, and to control the other of transistors Q1 and Q2 from the off state to the on state when the resonant current ILr is detected to commutate.

[0021] exist Figure 2 In the bridge power supply circuit 200 shown, when transistors Q1 / Q2 are first turned on, their on-current is small, therefore the required drive current is also small. The control chip U1 only needs to provide a small drive current to keep transistors Q1 / Q2 in the on state. As the on-current of transistors Q1 / Q2 increases, the drive current required to keep them in the on state also increases. At this time, the drive transformer W1 can provide sufficient drive current to transistors Q1 / Q2 through the coupling current of the resonant current ILr. When it is necessary to turn off transistors Q1 / Q2, the control chip U1 correspondingly pulls down the base voltage of transistors Q1 / Q2 to reliably turn them off, and controls them to turn on after detecting the commutation of the resonant current ILr.

[0022] Figure 3 It shows Figure 2 The circuit diagram of the transistor drive control circuit 300 in the control chip U1 is shown. Figure 3 As shown, the transistor drive control circuit 300 includes switches S1, S2, S3, and S4, and drive current-limiting resistors RB1 and RB2. The supply voltages HVCC and VCC are used to power the drive control circuits of transistors Q1 and Q2, respectively. Switch S1 is connected between the supply voltage HVCC and the base of transistor Q1; switch S2 is connected between the base and emitter of transistor Q1; switch S3 is connected between the supply voltage VCC and the base of transistor Q2; and switch S4 is connected between the base and emitter of transistor Q2. Here, it is assumed that each of switches S1, S2, S3, and S4 is closed when its control signal is high and open when its control signal is low.

[0023] Figure 4 Showing with Figure 3The timing diagram shown is related to multiple signals of the transistor drive control circuit 300. Here, ILr represents the resonant current on the winding W1a of the drive transformer W1, HB represents the voltage at the midpoint of the half-bridge between transistors Q1 and Q2, Vbe(Q1) represents the voltage difference between the base and emitter of transistor Q1, Ib(Q1) represents the base current of transistor Q1, Ice(Q1) represents the on-state current of transistor Q1, Vbe(Q2) represents the voltage difference between the base and emitter of transistor Q2, Ib(Q2) represents the base current of transistor Q2, Ice(Q2) represents the on-state current of transistor Q2, G1(S1) represents the control signal for controlling the closing and opening of switch S1, G2(S2) represents the control signal for controlling the closing and opening of switch S2, G3(S3) represents the control signal for controlling the closing and opening of switch S3, and G4(S4) represents the control signal for controlling the closing and opening of switch S4.

[0024] Combination Figure 3 and Figure 4 It can be seen that at time t0, the control chip U1 controls switch S4 to change from the open state to the closed state and keeps switches S1, S2, and S3 in the open state. At this time, the drive current provided by the drive transformer W1 is absorbed by switch S4. Due to the presence of stored charge in the transistor, transistor Q2 does not change from the on state to the off state until time t1. At this time, both the base voltage and base current of transistor Q2 become 0. At time t2, the voltage HB at the midpoint of the half-bridge rises to the bus voltage, the freewheeling diode D1 conducts, and the resonant current ILr flows through the freewheeling diode D1. At time t3, the control chip U1 detects the commutation of the resonant current ILr, controls switch S1 to change from the open state to the closed state, controls switch S4 to change from the closed state to the open state, and keeps switches S2 and S3 in the open state. At this time, transistor Q1 changes from the off state to the on state, and the drive current of transistor Q1 is provided by at least one of the control chip U1 and the drive transformer W1. At time t4, control chip U1 controls switch S1 to change from closed to open and keeps switches S2, S3, and S4 in the open state. At this time, drive transformer W1 continues to provide drive current to transistor Q1, and control chip U1 no longer needs to provide drive current to transistor Q1, thereby reducing the power consumption of control chip U1. During the period from time t5 to time t9, control chip U1 controls transistor Q1 to change from on to off and, after detecting the commutation of resonant current ILr, controls transistor Q2 to change from off to on. This control process is similar to the process of controlling transistor Q2 to change from on to off and controlling transistor Q1 to change from off to on during the period from time t0 to time t4, so it will not be described again.

[0025] In short, the control chip U1 can be configured to control switch S2 from the open state to the closed state and control switches S1, S3, and S4 to remain in the open state, and control transistor Q1 from the on state to the off state; and when the resonant current ILr is detected to commutate, it controls switch S2 from the closed state to the open state, controls switch S3 from the open state to the closed state, and controls switches S1 and S4 to remain in the open state, and controls transistor Q2 from the off state to the on state.

[0026] Furthermore, the control chip U1 can be configured to control switch S4 from the open state to the closed state and control switches S1, S2, and S3 to remain in the open state, thereby controlling transistor Q2 from the on state to the off state; and when the resonant current ILr is detected to commutate, it controls switch S4 from the closed state to the open state, controls switch S1 from the open state to the closed state, and controls switches S2 and S3 to remain in the open state, thereby controlling transistor Q1 from the off state to the on state.

[0027] Figure 5 It shows Figure 2 The circuit diagram shown is of the current commutation detection circuit 500 in the control chip U1. Figure 5 In the current commutation detection circuit 500 shown, the current source I1 is a mirror current source. Its output current I1 is proportional to the current flowing through the switch S2 and generates a voltage V1 on the resistor R1. The voltage V1 can characterize the current flowing through the switch S2. Figure 6 It shows the relationship with Figure 5 The timing diagram shown is related to multiple signals of the current commutation detection circuit 500, where ILr represents the resonant current on the winding W1a of the drive transformer W1, V1 represents the voltage on the resistor R1, G2 (S2) represents the control signal used to control the closing and opening of switch S2, and G3 (S3) represents the control signal used to control the closing and opening of switch S3.

[0028] The following is combined with Figure 5 and Figure 6 Taking the conduction control of transistor Q2 as an example, the working principle of the current commutation detection circuit 500 is explained. Figure 5 and Figure 6As shown, when switch S2 is closed, all the current flowing through winding W1b will flow through switch S2, and the current flowing through winding W1b is proportional to the resonant current ILr. When control chip U1 detects that the voltage V1 on resistor R1 is lower than the voltage threshold Vth_1, it can determine that the resonant current ILr has reversed, control switch S2 to change from closed to open, control switch S3 to change from open to closed, and control switches S1 and S4 to remain open. At this time, transistor Q2 changes from off to on. It should be noted that the conduction control of transistor Q1 is similar to that of transistor Q2, so it will not be described in detail.

[0029] In other words, the control chip U1 can be configured to: generate a mirror current source I1 by mirroring the current flowing through switch S2 when switch S2 is closed and switches S1, S3, and S4 are open, and detect whether the resonant current ILr has commutated by comparing the voltage generated on resistor R1 by the current I1 output by mirror current source I1 with a voltage threshold Vth_1; and generate a mirror current source I2 (not shown in the figure) by mirroring the current flowing through switch S4 when switch S4 is closed, and detect whether the resonant current ILr has commutated by comparing the voltage V2 (not shown in the figure) generated on resistor R2 (not shown in the figure) by the current I2 output by mirror current source I2 with a voltage threshold Vth_2 (not shown in the figure).

[0030] Figure 7 A circuit diagram of a bridge power supply circuit 700 according to another embodiment of the present invention is shown. Figure 7 The bridge power supply circuit 700 shown is... Figure 2 The only difference in the bridge power supply circuit 200 shown is that the control chip U1' detects whether the resonant current ILr has commutated by detecting the voltage VCS on the current sensing resistor RCS via the detection pin CS. It should be noted that... Figure 7 Other aspects of the bridge power supply circuit 700 shown are similar. Figure 2 The corresponding contents of the bridge power supply circuit 200 shown will not be described again.

[0031] Figure 8 It shows Figure 7 The circuit diagram shown is of the current commutation detection circuit 800 in the control chip U1'. Figure 8In the current commutation detection circuit 800 shown, when it is necessary to control transistor Q1 from the on state to the off state and control transistor Q2 from the off state to the on state, the control chip U1' performs the following processing: It controls switch S2 from the off state to the closed state and controls switches S1, S3, and S4 to remain in the off state, causing transistor Q1 to change from the on state to the off state; when the current detection voltage VCS is detected to be lower than the voltage threshold VCS_TH1, it determines that the resonant current ILr has commutated, controls switch S3 from the off state to the closed state, controls switch S2 from the closed state to the off state, and controls switches S1 and S4 to remain in the off state, causing transistor Q2 to change from the off state to the on state; after transistor Q2 has been in the on state for a period of time, it controls switch S3 to open, causing the drive transformer W1 to provide drive current to transistor Q2. The delay module can generate a delay signal through a delay circuit, or by determining that the current detection voltage VCS reaches a certain threshold, etc., which is not limited here.

[0032] Figure 9 Showing with Figure 8 The timing diagram shown relates to multiple signals of the current commutation detection circuit 800. From... Figure 9 It can be seen that when the current detection voltage VCS drops to the voltage threshold VCS_TH1, the control chip U1' determines that the resonant current ILr has reversed, controls switch S2 to change from closed to open, controls switch S3 to change from open to closed, and controls switches S1 and S4 to remain open, causing transistor Q2 to change from off to on. When the current detection voltage VCS rises to the voltage threshold VCS_TH2, the control chip U1' determines that the resonant current ILr has reversed, controls switch S4 to change from closed to open, controls switch S1 to change from open to closed, and controls switches S2 and S3 to remain open, causing transistor Q1 to change from off to on.

[0033] In other words, the control chip U1' can be configured to detect whether the resonant current ILr has commutated by comparing the current sensing voltage VCS characterizing the resonant current ILr with a voltage threshold CS_TH1 when switch S2 is closed and switches S1, S3, and S4 are open; and to detect whether the resonant current ILr has commutated by comparing the current sensing voltage VCS characterizing the resonant current ILr with a voltage threshold CS_TH2 when switch S4 is closed and switches S1, S2, and S3 are open.

[0034] Furthermore, such as Figure 8As shown, the control chip U1' can be configured to: generate a control signal G3 for controlling the closing and opening of switch S3 based on a first commutation characterization signal characterizing whether the resonant current ILr has commutated and a control signal G2 for controlling the closing and opening of switch S2, wherein switch S3 becomes open after being in the closed state for a predetermined time or when the current sensing voltage VCS reaches the threshold voltage VTH_CS1 (not shown in the figure); generate a control signal G1 for controlling the closing and opening of switch S1 based on a second commutation characterization signal characterizing whether the resonant current ILr has commutated and a control signal G4 for controlling the closing and opening of switch S4, wherein switch S1 becomes open after being in the closed state for a predetermined time or when the current sensing voltage VCS reaches the threshold voltage VTH_CS2 (not shown in the figure); generate a control signal G2 based on a clock control signal and control signal G3; and generate a control signal G4 based on a clock control signal and control signal G1, wherein the clock control signal is generated based on the output feedback signal FB.

[0035] In practical applications, the 500 / 800 current commutation detection circuit typically has a certain delay. To ensure that the switching transistors Q1 / Q2 can reliably turn on immediately after the resonant current ILr commutates, the current commutation detection thresholds Vth_1, Vth_2, VCS_TH1, and VCS_TH2 can be adjusted to detect the resonant current ILr commutation earlier. However, since the resonant current ILr has not yet commutated, releasing the pull-down control of switches S2 / S4 may cause the off-state transistors Q1 / Q2 to turn on again. To ensure reliable switching of transistors Q1 / Q2, the overlap time of switches S1 and S4 in the closed state and the overlap time of switches S2 and S3 in the closed state can be appropriately increased.

[0036] Figure 10 It shows the relationship with Figure 3 The timing diagram shows multiple signals related to the transistor drive control circuit 300. (Combined with...) Figure 3 and Figure 10It can be seen that when switch S4 changes from closed to open, the entire drive current induced in winding W1c flows through switch S4. At time t0, control chip U1 / U1' detects the zero-crossing state of resonant current ILr in advance. At this time, control switch S1 changes from open to closed and provides drive current. However, since winding W1c is short-circuited by switch S4 at this time, the current flowing out of switch S1 flows into switch S4 after being coupled through the winding of drive transformer W1. At this time, the current flowing into switch S4 is the sum of the coupling current generated by resonant current ILr through drive rheostat W1 and the coupling current generated by drive current provided by control chip U1 / U1' through drive transformer W1. At time t1, the control chip U1 / U1' changes the control switch S4 from closed to open. At this time, the drive current provided by the control chip U1 / U1' flows to the base of transistor Q1. The base current of transistor Q1 is the sum of the drive current provided by the control chip U1 / U1' and the coupling current generated by the resonant current ILr through the drive transformer W1. Although the coupling current ILr is negative at this time, it is still positive because ILr is already low, making the base of transistor Q1 forward biased and the base of transistor Q2 reverse biased. Therefore, transistor Q2 can remain reliably off. At time t2, the resonant current ILr reverses direction, and the coupling current provided to transistor Q1 through the drive transformer W1 becomes positive. At this time, the base current of transistor Q1 is the sum of the drive current provided by the control chip U1 / U1' and the coupling current generated by the resonant current ILr through the drive transformer W1. Transistor Q1 can reliably change from off to on. During the period from time t3 to time t5, the control chip U1 / U1' controls transistor Q1 to change from the on state to the off state, and after detecting the commutation of the resonant current ILr, it controls transistor Q2 to change from the off state to the on state. This control process is similar to the process of controlling transistor Q2 to change from the on state to the off state and controlling transistor Q1 to change from the off state to the on state during the period from time t0 to time t2, so it will not be described again.

[0037] In summary, the bridge power supply circuit according to embodiments of the present invention improves the reliability of transistor switching operation and significantly reduces the drive current supplied to the transistor by the control chip used to control the transistor's on / off state, thereby improving the transistor's drive efficiency. Compared with bridge power supply circuits using MOSFETs as switches, it can significantly reduce system costs.

[0038] This invention can be implemented in other specific forms without departing from its spirit and essential characteristics. For example, the algorithm described in a particular embodiment can be modified without departing from the basic spirit of the invention. Therefore, the present embodiments are to be regarded as exemplary rather than limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and all changes falling within the meaning and scope of the claims and their equivalents are thus included within the scope of the invention.

Claims

1. A bridge power supply circuit, comprising a first transistor, a second transistor, a drive transformer, and a transistor control circuit, wherein, The resonant current on the first winding of the drive transformer is used to provide drive current for the first and second transistors. The second winding of the drive transformer is connected between the base and emitter of the first transistor, and the third winding of the drive transformer is connected between the base and emitter of the second transistor. The transistor control circuit includes a first switch, a second switch, a third switch, and a fourth switch. The first switch is connected between a first supply voltage of the transistor control circuit and the base of the first transistor. The second switch is connected between the base and emitter of the first transistor. The third switch is connected between a second supply voltage of the transistor control circuit and the base of the second transistor. The fourth switch is connected between the base and emitter of the second transistor. The transistor control circuit is configured as follows: Based on the output feedback signal characterizing the output current or output voltage of the bridge power supply circuit, the second switch is controlled to change from the open state to the closed state while the first, third, and fourth switches are controlled to remain in the open state, and the first transistor is controlled to change from the on state to the off state. as well as When the resonant current is detected to have reversed, the second switch is controlled to change from closed to open, the third switch is controlled to change from open to closed, the first and fourth switches are controlled to remain open, and the second transistor is controlled to change from off to on.

2. The bridge power supply circuit as described in claim 1, wherein, The transistor control circuit is further configured as follows: By controlling the fourth switch to change from the open state to the closed state and controlling the first, second, and third switches to remain in the open state, the second transistor is controlled to change from the on state to the off state. as well as When the resonant current is detected to have reversed, the fourth switch is controlled to change from closed to open, the first switch is controlled to change from open to closed, the second and third switches are controlled to remain open, and the first transistor is controlled to change from off to on.

3. The bridge power supply circuit as described in claim 2, wherein, The duration of the fourth switch being closed overlaps with the duration of the first switch being closed, and the duration of the third switch being closed overlaps with the duration of the second switch being closed.

4. The bridge power supply circuit as described in claim 1, wherein, The transistor control circuit is further configured to operate during the period when the second switch is closed and the first, third, and fourth switches are open: A first mirror current source is generated by mirroring the current flowing through the second switch; The resonant current is detected to have commutated by comparing the first voltage generated on the first resistor by the first current output from the first mirror current source with a first voltage threshold.

5. The bridge power supply circuit as described in claim 1, wherein, The transistor control circuit is further configured to operate during the period when the fourth switch is closed and the first, second, and third switches are open: A second mirror current source is generated by mirroring the current flowing through the fourth switch; The resonant current is detected to have commutated by comparing the second voltage generated on the second resistor by the second current output from the second mirror current source with a second voltage threshold.

6. The bridge power supply circuit as described in claim 1, wherein, The transistor control circuit is further configured to operate during the period when the second switch is closed and the first, third, and fourth switches are open: Whether the resonant current has commutated is detected by comparing the current sensing voltage characterizing the resonant current with a third voltage threshold.

7. The bridge power supply circuit as described in claim 1, wherein, The transistor control circuit is further configured to operate during the period when the fourth switch is closed and the first, second, and third switches are open: Whether the resonant current has commutated is detected by comparing the current sensing voltage characterizing the resonant current with a fourth voltage threshold.

8. The bridge power supply circuit as described in claim 6, wherein, The transistor control circuit is further configured as follows: Based on a first commutation characterization signal indicating whether the resonant current has commutated and a second control signal for controlling the closing and opening of the second switch, a third control signal for controlling the closing and opening of the third switch is generated, wherein... The third switch is turned off after being in the closed state for a predetermined time or when the current sensing voltage reaches the fifth threshold voltage.

9. The bridge power supply circuit as described in claim 7, wherein, The transistor control circuit is further configured as follows: Based on a second commutation characterization signal characterizing whether the resonant current has commutated and a fourth control signal for controlling the closing and opening of the fourth switch, a first control signal for controlling the closing and opening of the first switch is generated, wherein... The first switch is turned off after being in the closed state for a predetermined time or when the current sensing voltage reaches the sixth threshold voltage.

10. The bridge power supply circuit as described in claim 8, wherein, The transistor control circuit is further configured as follows: The second control signal is generated based on the clock control signal and the third control signal, wherein the clock control signal is generated based on the output feedback signal.

11. The bridge power supply circuit as described in claim 9, wherein, The transistor control circuit is further configured as follows: The fourth control signal is generated based on the clock control signal and the first control signal, wherein the clock control signal is generated based on the output feedback signal.

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