Isolation type conversion device with magnetic bias balance control and magnetic bias balance control method

Abstract

An isolated converter with magnetic bias balance control includes an isolated converter, a controller, and a magnetic bias balance circuit. The isolated converter includes a transformer, and the primary side of the transformer includes a primary winding and at least one switching arm. The controller is coupled to at least one switching arm and provides a pulse width modulation (PWM) signal group to control the at least one switching arm. The magnetic bias balance circuit is coupled to both ends of the primary winding and the controller, and provides a compensation voltage to the controller based on the average voltage across the primary winding. The controller adjusts the duty cycle of the PWM signal group according to the compensation voltage to correct the magnetic bias.

Description

Technical Field

[0001] This invention relates to a magnetic bias balance control method for a conversion device, and particularly to a magnetic bias balance control method for an isolated conversion device. Background Technology

[0002] Figure 1A This is based on the existing full-bridge phase-shift converter circuit architecture. Due to differences in hardware circuitry or variations in the switching duty cycles of control switches Q1 to Q4, the average positive and negative cross-voltage of transformer 12 is not zero, resulting in a phenomenon where the average magnetizing current is not zero (referred to as magnetic bias). Ultimately, this leads to saturation of the magnetizing inductance of transformer 12, causing a rapid decrease in inductance value and posing a risk of excessive current on the primary side of the converter.

[0003] Therefore, in existing technology, a capacitor C is typically connected in series with the primary side of transformer 12 to balance the voltage across the positive and negative half-cycles of transformer 12 and avoid magnetic deflection. However, this control method requires adding a capacitor C to the circuit, which relatively increases the circuit cost and size. Another common solution is... Figure 1B As shown, a current sensor (CT) is added to this full-bridge circuit, and the peak current control method is used. This control method causes the switch duty cycle to be turned off earlier during the half-cycle of magnetic bias due to the higher current, thus reducing the voltage-time product on the magnetic bias side and achieving the effect of balancing the magnetic bias. However, this control method requires an additional current sensor (CT) in the circuit, which also increases the circuit cost and size.

[0004] Therefore, how to design an isolated conversion device with magnetic bias balance control and its magnetic bias balance control method, without using a control method that adds a current sensor or an isolation capacitor to balance the magnetic bias, is a major research topic that the inventors of this disclosure intend to conduct. Summary of the Invention

[0005] To address the aforementioned problems, the present invention provides an isolated converter with magnetic bias balance control to overcome the limitations of existing technologies. Therefore, the isolated converter of the present invention includes: an isolated converter comprising a transformer, the primary side of which includes a primary winding and at least one switching arm; a controller coupled to the at least one switching arm and providing a pulse width modulation signal group to control the at least one switching arm; and a magnetic bias balance circuit coupled to both ends of the primary winding and the controller, providing a compensation voltage to the controller based on the average voltage of the winding voltages across the primary winding; wherein the controller adjusts the duty cycle of the pulse width modulation signal group according to the compensation voltage.

[0006] To address the aforementioned problems, the present invention provides a magnetic bias balance control method for an isolated converter to overcome the limitations of existing technologies. Therefore, the isolated converter includes an isolated converter, and the isolated converter includes a transformer and at least one switching arm connected to the primary side of the transformer. The magnetic bias balance control method of the present invention includes the following steps: (a) providing a pulse width modulation signal group to control the switching of at least one switching arm to convert the input voltage to an output voltage by the isolated converter; (b) providing a compensation voltage for the magnetic bias of the transformer based on the winding voltage across the primary winding of the transformer; and (c) adjusting the duty cycle of the pulse width modulation signal group according to the compensation voltage to correct the magnetic bias.

[0007] The main objective and technical effect of this invention is that by using the winding voltage at both ends of the primary winding of the sampling transformer, taking its average value through a filter circuit, and then controlling it to 0 through a controller to correct the magnetic bias, the control method of adding a current sensor and the isolation capacitor can be eliminated, thereby achieving the technical effect of reducing circuit size and circuit cost.

[0008] To gain a deeper understanding of the techniques, means, and effects employed by this invention to achieve its intended purpose, please refer to the following detailed description and accompanying drawings. It is believed that the purpose, features, and characteristics of this invention can be understood in a thorough and specific manner from these drawings. However, the accompanying drawings are provided for reference and illustration only and are not intended to limit this invention. Attached Figure Description

[0009] Figure 1A This is based on the existing full-bridge phase-shift converter circuit architecture;

[0010] Figure 1B This is a control block diagram for peak current control.

[0011] Figure 2 This is a circuit block diagram of the isolated conversion device with magnetic bias balance control of the present invention;

[0012] Figure 3 This is a circuit block diagram of the controller and magnetic deflection balance circuit of the present invention;

[0013] Figure 4A This is a circuit block diagram of a first embodiment of the isolated converter of the present invention;

[0014] Figure 4B This is a circuit block diagram of a second embodiment of the isolated converter of the present invention;

[0015] Figure 5A This is a waveform diagram illustrating the correction of positive magnetic bias in the isolated conversion device according to the first embodiment of the present invention.

[0016] Figure 5BThis is a waveform diagram illustrating the correction of negative magnetic bias in the isolated conversion device according to the first embodiment of the present invention.

[0017] Figure 6A This is a flowchart of the magnetic bias balance control method for the isolated conversion device of the present invention; and

[0018] Figure 6B This is a flowchart of the method for adjusting the duty cycle of the isolated conversion device of the present invention.

[0019] Explanation of reference numerals in the attached figures:

[0020] 1, 1'...Isolation type conversion device

[0021] 1A…Input Terminal

[0022] 1B…output terminal

[0023] 10, 10'... Isolated converter

[0024] 12…Transformer

[0025] 122… Primary winding

[0026] 124… Secondary winding

[0027] 14… Switch bridge arm

[0028] 142…First bridge arm

[0029] Q1…First Switch

[0030] Q2…Second switch

[0031] 144…Second bridge arm

[0032] Q3…Third switch

[0033] Q4…Fourth switch

[0034] 146… capacitor bank

[0035] C1…First capacitor

[0036] C2…Second capacitor

[0037] 16…Secondary side circuit

[0038] 20… controller

[0039] 22…First Operational Circuit

[0040] 24…Voltage Controller

[0041] 26…Pulse Width Modulation Circuit

[0042] 30…Magnetic bias balancing circuit

[0043] 32…Sampling Circuit

[0044] 322…Operational Amplifier

[0045] I1…First input terminal

[0046] I2…Second Input Terminal

[0047] O…output terminal

[0048] 324… filter circuit

[0049] Rf1…First filter resistor

[0050] Rf2…Second filter resistor

[0051] Cf… filter capacitor

[0052] 326…First voltage divider circuit

[0053] R1…First resistor

[0054] R2…Second resistor

[0055] 328…Second voltage divider circuit

[0056] R3…Third resistor

[0057] R4…the fourth resistor

[0058] 34…Offset Compensation Circuit

[0059] 342…Second Operational Circuit

[0060] 344… proportional-integral unit

[0061] 2…load

[0062] Lr…excitation inductor

[0063] C…capacitor

[0064] CT…current sensor

[0065] Vin…Input Voltage

[0066] Vo…output voltage

[0067] Vw…winding voltage

[0068] Vc…compensation voltage

[0069] Vref…reference voltage

[0070] Ve1…First error value

[0071] Ve2…Second error value

[0072] Va…average voltage

[0073] Vz…zero voltage

[0074] PWM...Pulse Width Modulation Signal Group

[0075] Sf…feedback signal

[0076] Sv…voltage control signal

[0077] S1…First control signal

[0078] S2…Second control signal

[0079] S3…Third control signal

[0080] S4…Fourth control signal

[0081] A…arrow

[0082] (S100)~(S340)…Steps Detailed Implementation

[0083] The technical content and detailed description of the present invention are explained below with reference to the accompanying drawings:

[0084] Please see Figure 2 This is a circuit block diagram of the isolated converter with magnetic bias balance control according to the present invention. The input terminal 1A of the isolated converter 1 receives the input voltage Vin and converts it into an output voltage Vo to supply power to the load 2 through the output terminal 1B. The isolated converter 1 includes an isolated converter 10, a controller 20, and a magnetic bias balance circuit 30. The isolated converter 10 includes a transformer 12, at least one switching bridge arm 14, and a secondary side circuit 16. The primary side of the transformer 12 includes a primary winding 122, and the secondary side includes a secondary winding 124. The switching bridge arm 14 is coupled to the input terminal 1A and the primary winding 122, and the secondary side circuit 16 is coupled to the secondary winding 124 and the output terminal 1B. The controller 20 is coupled to the switching bridge arm 14 and the output terminal 1B, and provides a pulse width modulation (PWM) signal group to control the switching bridge arm 14 according to the feedback signal Sf from the output terminal 1B. The magnetic bias balancing circuit 30 is coupled to the two ends of the primary winding 122 and the controller 20, and provides a corresponding magnetic bias compensation voltage Vc to the controller 20 based on the winding voltage Vw at the two ends of the primary winding 122. The controller 20 adjusts the duty cycle of the pulse width modulation signal group (PWM) according to the compensation voltage Vc to correct the magnetic bias of the transformer 12 and achieve the effect of magnetic bias balancing.

[0085] Please see Figure 3 This is a circuit block diagram of the controller and magnetic bias balance circuit of the present invention, for further reference. Figure 2The controller 20 includes a first operational circuit 22, a voltage controller 24, and a pulse width modulation circuit 26. The first operational circuit 22 is coupled to the output terminal 1B and provides a first error value Ve1 to the voltage controller 24 based on the difference between the feedback signal Sf from the output terminal 1B and the reference voltage Vref. The voltage controller 24 is a compensator for general feedback control, receives the first error value Ve1, generates a voltage control signal Sv based on the first error value Ve1, and provides the voltage control signal Sv to the pulse width modulation circuit 26. The pulse width modulation circuit 26 modulates a pulse width modulation signal group (PWM) according to the voltage control signal Sv and provides the PWM signal group to the switching bridge arm 14 to stabilize the voltage value of the output voltage Vo by controlling the switching of the switching bridge arm 14. It is worth mentioning that, in one embodiment of the present invention, the internal structure of the controller 20 is only the most basic feedback control architecture, and the controller 20 is not limited to being implemented with only this circuit architecture.

[0086] The magnetic bias balancing circuit 30 includes a sampling circuit 32 and an offset compensation circuit 34. The sampling circuit 32 is coupled to both ends of the primary winding 122, and the offset compensation circuit 34 is coupled to the sampling circuit 32 and outputs a compensation voltage Vc to the pulse width modulation circuit 26 of the controller 20. Schematic, the sampling circuit 32 is a differential filter circuit, and the differential filter circuit (i.e., the sampling circuit 32) includes an operational amplifier 322, a filter circuit 324, a first voltage divider circuit 326, and a second voltage divider circuit 328. The operational amplifier 322 includes a first input terminal I1, a second input terminal I2, and an output terminal O, and the offset compensation circuit 34 is coupled to the output terminal O of the operational amplifier 322. One end of the filter circuit 324 is coupled to both ends of the primary winding 122, and the other end is coupled to the first voltage divider circuit 326 and the second voltage divider circuit 328, respectively. Specifically, the filter circuit 324 includes a first filter resistor Rf1, a second filter resistor Rf2, and a filter capacitor Cf. One end of the first filter resistor Rf1 is coupled to one end of the primary winding 122, and the other end of the first filter resistor Rf1 is coupled to the first voltage divider circuit 326. One end of the second filter resistor Rf2 is coupled to the other end of the primary winding 122, and the other end of the second filter resistor Rf2 is coupled to the second voltage divider circuit 328. One end of the filter capacitor Cf is coupled to the other end of the first filter resistor Rf1, and the other end of the filter capacitor Cf is coupled to the other end of the second filter resistor Rf2.

[0087] The first voltage divider circuit 326 includes a first resistor R1 and a second resistor R2 connected in series. The first resistor R1 is coupled to one end of the filter capacitor Cf, and the two ends of the second resistor R2 are respectively coupled to the first input terminal I1 and the output terminal O of the operational amplifier 322. The second voltage divider circuit 328 includes a third resistor R3 and a fourth resistor R4 connected in series. The third resistor R3 is coupled to the other end of the filter capacitor Cf, and the two ends of the fourth resistor R4 are respectively coupled to the second input terminal I2 and the negative terminal. The sampling circuit 32 filters, averages, and adjusts the gain of the winding voltage Vw through the filter circuit 324, the operational amplifier 322, the first voltage divider circuit 326, and the second voltage divider circuit 328 to generate an average voltage Va that is related to the average voltage value of the winding voltage Vw. It is worth mentioning that, in one embodiment of the present invention, the implementation of the sampling circuit 32 is only an illustrative implementation (presented in the form of an analog circuit) and is not limited to only using analog circuits. Figure 3 The circuit structure of the differential filter circuit is implemented. As another possible implementation, the average voltage of the positive and negative half-cycles of the winding voltage Vw can be taken respectively. Then, the average voltage of the positive half-cycle is subtracted from the average voltage of the negative half-cycle to obtain an average voltage Va related to the average voltage of the winding voltage Vw. This average voltage Va is then used by the offset compensation circuit 34 to control the difference to zero. This implementation is advantageous for use with a processor or microcontroller. In other words, any circuit or method that can obtain the average value of the winding voltage Vw can be applied to the sampling circuit 32 of this invention.

[0088] The offset compensation circuit 34 is a proportional-integral (PI) controller, and the PI controller (i.e., the offset compensation circuit 34) includes a second operational circuit 342 and a proportional-integral (PI) unit 344. The operational circuit 342 provides a second error value Ve2 based on the difference between the average voltage Va and the zero voltage Vz, where the zero voltage Vz represents the target value for magnetic deflection balance, typically a reference voltage of 0V. The PI unit 344 receives the second error value Ve2 and generates a compensation voltage Vc related to the direction and magnitude of magnetic deflection, providing the compensation voltage Vc to the pulse width modulation (PWM) circuit 26. This allows the PWM circuit 26 to adjust the duty cycle of the PWM signal group according to the compensation voltage Vc to correct the magnetic deflection. It is worth noting that in one embodiment of the present invention, the implementation of the offset compensation circuit 34 is only a preferred embodiment and is not limited to only using... Figure 3 The offset compensation circuit 34 of this invention is implemented using a proportional-integral controller. In other words, any controller architecture that can generate a compensation voltage Vc based on the average voltage Va and the zero voltage Vz to make the average voltage Va close to zero can be applied to the offset compensation circuit 34 of this invention. The offset compensation circuit 34 can also be implemented using a processor or microcontroller in conjunction with digital control.

[0089] Please see Figure 4AThis is a circuit block diagram of the first embodiment of the isolated converter of the present invention, which can be further referenced. Figures 2-3 The isolated converter 10 in the isolated conversion device 1 has a full-bridge converter circuit architecture, therefore the switch bridge arm 14 includes a first bridge arm 142 and a second bridge arm 144. The first bridge arm 142 includes a first switch Q1 and a second switch Q2 connected in series, the second bridge arm 144 is connected in parallel with the first bridge arm 142, and the second bridge arm 144 includes a third switch Q3 and a fourth switch Q4 connected in series. One end of the primary winding 122 is coupled to the node between the first switch Q1 and the second switch Q2, and the other end of the primary winding 122 is coupled to the node between the third switch Q3 and the fourth switch Q4. The pulse width modulation signal group PWM includes a first control signal S1 controlling the first switch Q1, a second control signal S2 controlling the second switch Q2, a third control signal S3 controlling the third switch Q3, and a fourth control signal S4 controlling the fourth switch Q4. The controller 20 provides control signals S1 to S4 based on the feedback signal Sf from the output terminal 1B to control the switching of switches Q1 to Q4, so that the isolated converter 10 converts the input voltage Vin into the output voltage Vo. The magnetic deflection balancing circuit 30 is coupled to both ends of the primary winding 122, and provides the corresponding compensation voltage Vc for the magnetic deflection of the transformer 12 to the controller 20 based on the winding voltage Vw, so that the controller 20 adjusts the duty cycle of the control signals S1 to S4, thereby correcting the magnetic deflection of the transformer 12 and achieving the effect of magnetic deflection balance.

[0090] Furthermore, please refer to Figure 5A For a waveform diagram illustrating the correction of positive magnetic bias in the isolated conversion device of the first embodiment of the present invention, please refer to [link / reference]. Figure 5B This is a waveform diagram illustrating the correction of negative magnetic bias in the isolated conversion device according to the first embodiment of the present invention. See also the attached diagram. Figures 2 to 4A The compensation voltage Vc provided by the magnetic deflection balancing circuit 30 corresponds to the magnetic deflection direction of the transformer, either towards the positive half-cycle or the negative half-cycle. Please refer to [link / reference]. Figure 5A When the magnetic deflection of transformer 12 is positive, the effective duty cycle of the positive half-cycle of the winding voltage Vw will be larger than that of the negative half-cycle. At this time, the compensation voltage Vc provided by the magnetic deflection balancing circuit 30 based on the winding voltage Vw will be positive (i.e., greater than 0V). The controller 20 adjusts the duty cycle of the first control signal S1 and the fourth control signal S4 based on the positive compensation voltage Vc (arrow A indicates the reduction of the duty cycle) to reduce the effective duty cycle of the positive half-cycle, thereby correcting the magnetic flux deviating towards the positive value. Here, the effective duty cycle refers to the actual duty cycle of the winding voltage Vw. Figure 4ATaking a full-bridge converter as an example, control signals S1 and S4 can generally be turned on and off synchronously, so the effective duty period is equal to the duty period of control signal S1 or control signal S4. If phase shift control is used, since control signals S1 and S4 are not synchronized, there will only be voltage on the winding when control signals S1 and S4 are both high. Therefore, the effective duty period is the time when the high levels of control signals S1 and S4 overlap.

[0091] Conversely, please refer to Figure 5B When the magnetic deflection of transformer 12 is negative, the effective duty period of the negative half-cycle of the winding voltage Vw will be larger than that of the positive half-cycle. At this time, the compensation voltage Vc provided by the magnetic deflection balancing circuit 30 based on the winding voltage Vw will be negative (i.e., less than 0V). The controller 20 adjusts the duty cycle of the second control signal S2 and the third control signal S3 (arrow A indicates reduced duty cycle) based on the negative compensation voltage Vc to reduce the effective duty period of the negative half-cycle, thereby correcting the negative magnetic deflection. It is worth noting that in one embodiment of the present invention, the correspondence between the positive and negative values ​​of the winding voltage Vw and the compensation voltage Vc is merely an example. Conversely, a negative compensation voltage Vc can be generated for the winding voltage Vw with a larger effective duty period in the positive half-cycle, as long as it can be controlled to reduce the effective duty period of the half-cycle with a larger effective duty period.

[0092] Please see Figure 4B This is a circuit block diagram of a second embodiment of the isolated converter of the present invention, which can be further referenced. Figures 2 to 4A , Figures 5A-5B The isolated conversion device 1' in this embodiment and Figure 4AThe difference between the isolated converter 1 and the isolated converter 10' is that the isolated converter 10' has a half-bridge converter circuit architecture. The switching bridge arm 14 includes a first bridge arm 142 and a capacitor bank 146. The first bridge arm 142 includes a first switch Q1 and a second switch Q2 connected in series. The capacitor bank 146 is connected in parallel to the first bridge arm 142 and includes a first capacitor C1 and a second capacitor C2 connected in series. One end of the primary winding 122 is coupled to the node between the first switch Q1 and the second switch Q2, and the other end of the primary winding 122 is coupled to the node between the first capacitor C1 and the second capacitor C2. The pulse width modulation (PWM) signal group includes a first control signal S1 controlling the first switch Q1 and a second control signal S2 controlling the second switch Q2. The controller 20 provides control signals S1 to S2 respectively to control the switching of switches Q1 to Q2 based on the feedback signal Sf from the output terminal 1B, so that the isolated converter 10 converts the input voltage Vin into the output voltage Vo. The magnetic deflection balancing circuit 30 provides a compensation voltage Vc to the controller 20 to compensate for the magnetic deflection of the transformer 12 based on the winding voltage Vw. This causes the controller 20 to adjust the duty cycle of the control signals S1 to S2, thereby correcting the magnetic deflection of the transformer 12 and achieving magnetic deflection balance. It is worth noting that, in one embodiment of the present invention, the waveform of the isolated conversion device 1' correcting the magnetic flux deviation is similar to... Figure 5A and Figure 5B When the duty cycle of the positive half-cycle of the winding voltage Vw is large, the duty cycle of the first control signal S1 is reduced, and when the duty cycle of the negative half-cycle of the winding voltage Vw is large, the duty cycle of the second control signal S2 is reduced.

[0093] It is worth mentioning that, in one embodiment of the present invention, the secondary side circuit 16 can be Figure 4A and Figure 4B The diagram shows a full-bridge rectifier circuit architecture, but it can also be a center-tapped rectifier circuit, which can be implemented according to the actual needs of the circuit. Furthermore, although the magnetic deflection balancing circuit 30 can also use the secondary-side winding 124 for magnetic deflection balancing control, the structure of the secondary-side winding 124 will change due to different circuit types of the secondary-side circuit 16 (single winding or center-tapped), thus making the magnetic deflection balancing circuit 30 unsuitable for all circuit architectures of the secondary-side circuit 16. Especially in center-tapped windings, the parameters of the two windings cannot be made completely identical, resulting in the inability to achieve complete magnetic deflection balancing even with magnetic deflection balancing control. The advantage of the magnetic deflection balancing circuit 30 of this invention using the primary-side winding 122 for magnetic deflection balancing control is that regardless of whether the primary-side switching bridge arm 14 is a single bridge arm or a double bridge arm (e.g., ...), it can achieve magnetic deflection balancing. Figure 4A and Figure 4B As shown, the magnetic bias balancing circuit 30 is universal, which can increase the ease of use. Moreover, since the primary winding 122 has only a single winding, the magnetic bias balancing control of this invention can achieve a completely balanced magnetic bias.

[0094] In summary, the isolated conversion device 1 of the present invention utilizes the winding voltage Vw across the primary winding 122 of the sampling transformer 12, and takes its average value through a filter circuit (i.e., sampling circuit 32), then controls it to 0 through a controller (i.e., offset compensation circuit 34) to correct the magnetic bias. The average value of the winding voltage Vw across the primary winding 122 is equal to the product of voltage and time (effective duty period). This allows for simple compensation of transformer magnetic bias without the need for a control method that adds a current sensor or an isolation capacitor, thereby achieving the technical effect of reducing circuit size and cost.

[0095] Please see Figure 6A This is a flowchart of the magnetic bias balance control method for the isolated conversion device of the present invention, which can be further referenced. Figures 2 to 5B The magnetic bias balance control method is applicable to controlling an isolated converter 1 with a transformer 12, wherein the primary side of the transformer 12 includes at least one switching arm 14. The magnetic bias balance control method includes: providing a pulse width modulation (PWM) signal group to control the switching arm switching so that the isolated converter converts the input voltage to the output voltage (S100). The controller 20 provides a PWM signal group based on the feedback signal Sf from the output terminal 1B of the isolated converter 1 to control the switching of the switching arm 14, so that the isolated converter 1 converts the input voltage Vin to the output voltage Vo. Then, a magnetic bias compensation voltage corresponding to the transformer is provided based on the winding voltage at both ends of the primary winding of the transformer and zero voltage (S200). The sampling circuit 32 in the magnetic bias balance circuit 30 filters and averages the winding voltage Vw through the filter circuit 324, and then adjusts the gain through the operational amplifier 322, the first voltage divider circuit 326, and the second voltage divider circuit 328 to generate an average voltage Va related to the average voltage value of the winding voltage Vw. The operational circuit 342 provides a second error value Ve2 based on the difference between the average voltage Va and the zero voltage Vz. The proportional-integral unit 344 generates a compensation voltage Vc related to the direction and magnitude of magnetic deflection based on the second error value Ve2, and provides the compensation voltage Vc to the pulse width modulation circuit 26. Finally, the duty cycle of the pulse width modulation signal group is adjusted according to the compensation voltage to correct the magnetic deflection (S300). The pulse width modulation circuit 26 adjusts the duty cycle of the pulse width modulation signal group PWM according to the compensation voltage Vc to correct the magnetic deflection.

[0096] Please see Figure 6B This is a flowchart of the method for adjusting the duty cycle of the isolated switching device of the present invention, which can be further referenced. Figures 2 to 6AStep (S300) includes providing a compensation voltage corresponding to the magnetic deflection direction (S320). The compensation voltage Vc provided by the magnetic deflection balancing circuit 30 corresponds to the magnetic deflection direction, and the magnetic deflection has a direction of deviation towards the positive half-cycle or the negative half-cycle. Then, the duty cycle of the control signal corresponding to the deviation direction is reduced according to the compensation voltage corresponding to the magnetic deflection direction (S340). When the isolated converter 10 in the isolated converter device 1 has a full-bridge converter circuit architecture, and the magnetic deflection direction generated by the transformer 12 is positive, the effective duty cycle of the positive half-cycle of the winding voltage Vw will be larger than that of the negative half-cycle. At this time, the compensation voltage Vc provided by the magnetic deflection balancing circuit 30 according to the winding voltage Vw will be positive, and the controller 20 will reduce the duty cycle of the first control signal S1 and the fourth control signal S4 according to the positive compensation voltage Vc. Conversely, the duty cycle of the second control signal S2 and the third control signal S3 will be reduced.

[0097] When the isolated converter 10 in the isolated converter device 1 has a half-bridge converter circuit architecture, and the magnetic deflection direction of the transformer 12 is positive, the duty cycle of the positive half-cycle of the winding voltage Vw will be larger than that of the negative half-cycle. At this time, the compensation voltage Vc provided by the magnetic deflection balancing circuit 30 based on the winding voltage Vw will be positive, and the controller 20 will reduce the duty cycle of the first control signal S1 based on the positive compensation voltage Vc. Conversely, it will reduce the duty cycle of the second control signal S2.

[0098] The above description is merely a detailed description and accompanying drawings of preferred embodiments of the present invention, and the features of the present invention are not limited thereto, nor are they intended to limit the present invention. The entire scope of the present invention should be determined by the following claims. All embodiments that conform to the concept of the claims of the present invention and similar variations thereof should be included in the scope of the present invention. Any variations or modifications that can be easily conceived by those skilled in the art within the field of the present invention can be covered by the following claims of the present disclosure.

Claims

1. An isolated switching device with magnetic bias balance control, comprising: An isolated converter includes a transformer, the primary side of which includes a primary winding and at least one switching arm; A controller is coupled to the at least one switch bridge arm and provides a pulse width modulation signal group to control the at least one switch bridge arm; and A magnetic bias balancing circuit is coupled between the two ends of the primary winding and the controller, and provides a compensation voltage to the controller based on an average voltage value of the winding voltage across the primary winding; wherein the controller adjusts the duty cycle of the pulse width modulation signal group according to the compensation voltage. The magnetic bias balancing circuit includes: A sampling circuit is coupled to both ends of the primary winding and generates an average voltage with respect to the average voltage value. and An offset compensation circuit is coupled to the sampling circuit and provides the compensation voltage based on the average voltage and a zero voltage.

2. The isolated conversion device as claimed in claim 1, wherein the sampling circuit is a differential filter circuit, and the differential filter circuit comprises: An operational amplifier includes a first input terminal, a second input terminal, and an output terminal, wherein the output terminal is coupled to the offset compensation circuit. A filter circuit is coupled to both ends of the primary winding; A first voltage divider circuit includes a first resistor and a second resistor connected in series. The first resistor is coupled to the filter circuit, and the two ends of the second resistor are respectively coupled to the first input terminal and the output terminal; and A second voltage divider circuit includes a third resistor and a fourth resistor connected in series. The third resistor is coupled to the filter circuit, and the two ends of the fourth resistor are respectively coupled to the second input terminal and a negative terminal.

3. The isolated conversion device as described in claim 2, wherein the filter circuit comprises: A first filter resistor, one end of which is coupled to one end of the primary winding, and the other end of which is coupled to the first resistor; A second filter resistor, one end of which is coupled to the other end of the primary winding, and the other end of which is coupled to the third resistor; and A filter capacitor, one end of which is coupled to the other end of the first filter resistor, and the other end of which is coupled to the other end of the second filter resistor.

4. The isolated conversion device as claimed in claim 1, wherein the offset compensation circuit is a proportional-integral controller, and the proportional-integral controller comprises: An operational circuit is coupled to the sampling circuit and provides an error value based on the difference between the average voltage and the zero voltage; A proportional-integral unit receives the error value and generates the compensation voltage based on the error value.

5. The isolated switching device as claimed in claim 1, wherein the at least one switching bridge arm comprises: A first bridge arm includes a first switch and a second switch connected in series; and A capacitor bank, connected in parallel to the first bridge arm, and including a first capacitor and a second capacitor connected in series; Wherein, one end of the primary winding is coupled to the node between the first switch and the second switch, and the other end of the primary winding is coupled to the node between the first capacitor and the second capacitor; the pulse width modulation signal group includes a first control signal for controlling the first switch and a second control signal for controlling the second switch.

6. The isolated conversion device of claim 5, wherein the compensation voltage provided by the magnetic deflection balancing circuit is associated with a first magnetic deflection direction of the transformer, and the controller reduces the duty cycle of the first control signal according to the compensation voltage associated with the first magnetic deflection direction.

7. The isolated conversion device of claim 5, wherein the compensation voltage provided by the magnetic deflection balancing circuit is associated with a second magnetic deflection direction of the transformer, and the controller reduces the duty cycle of the second control signal according to the compensation voltage associated with the second magnetic deflection direction.

8. The isolated switching device as claimed in claim 1, wherein the at least one switching bridge arm comprises: A first bridge arm includes a first switch and a second switch connected in series; and A second bridge arm, connected in parallel to the first bridge arm, and including a third switch and a fourth switch connected in series; Wherein, one end of the primary winding is coupled to the node between the first switch and the second switch, and the other end of the primary winding is coupled to the node between the third switch and the fourth switch; the pulse width modulation signal group includes a first control signal controlling the first switch, a second control signal controlling the second switch, a third control signal controlling the third switch, and a fourth control signal controlling the fourth switch.

9. The isolated conversion device of claim 8, wherein the compensation voltage provided by the magnetic deflection balancing circuit corresponds to a first magnetic deflection direction of the transformer, and the controller adjusts the duty cycle of the first control signal and the fourth control signal according to the compensation voltage corresponding to the first magnetic deflection direction.

10. The isolated conversion device of claim 8, wherein the compensation voltage provided by the magnetic deflection balancing circuit corresponds to a second magnetic deflection direction of the transformer, and the controller adjusts the duty cycle of the second control signal and the third control signal according to the compensation voltage corresponding to the second magnetic deflection direction.

11. A magnetic bias balance control method for an isolated converter, the isolated converter including an isolated converter, the isolated converter including a transformer and at least one switching bridge arm coupled to the primary side of the transformer, the magnetic bias balance control method comprising the following steps: (a) A pulse width modulation signal group is provided to control the switching of the at least one switch bridge arm so that the isolated converter converts an input voltage into an output voltage; (b) To provide a compensating voltage for a magnetic deflection of the transformer based on a winding voltage across a primary winding of the transformer; and (c) Adjust the duty cycle of the pulse width modulation signal group according to the compensation voltage to correct the magnetic bias. Step (b) includes: (b1) Generate an average voltage with respect to an average voltage value of the winding voltage; (b2) Provide an error value based on the difference between the average voltage and a zero voltage; and (b3) Generate the compensation voltage based on the error value.

12. The magnetic bias balance control method of claim 11, wherein the pulse width modulation signal group includes a first control signal and a second control signal for controlling the at least one switching bridge arm, and step (c) includes: (c11) Provide the compensation voltage associated with a first magnetic deflection direction in the magnetic deflection; and (c12) The duty cycle of the first control signal is reduced according to the compensation voltage associated with the first magnetic deflection direction.

13. The magnetic bias balance control method of claim 11, wherein the pulse width modulation signal group includes a first control signal and a second control signal for controlling the at least one switching bridge arm, and step (c) includes: (c21) Provide the compensation voltage corresponding to a second magnetic deflection direction in the magnetic deflection; and (c22) Adjust the duty cycle of the second control signal according to the compensation voltage corresponding to the second magnetic deflection direction.

14. The magnetic bias balance control method of claim 11, wherein the pulse width modulation signal group includes a first control signal, a second control signal, a third control signal, and a fourth control signal for controlling the at least one switching bridge arm, and step (c) includes: (c31) Provide the compensation voltage corresponding to a first magnetic deflection direction in the magnetic deflection; and (c32) Adjust the duty cycle of the first control signal and the fourth control signal according to the compensation voltage corresponding to the first magnetic deflection direction.

15. The magnetic bias balance control method of claim 11, wherein the pulse width modulation signal group includes a first control signal, a second control signal, a third control signal, and a fourth control signal for controlling the at least one switching bridge arm, and step (c) includes: (c41) Provide the compensation voltage corresponding to a second magnetic deflection direction in the magnetic deflection; and (c42) Adjust the duty cycle of the second control signal and the third control signal according to the compensation voltage corresponding to the second magnetic deflection direction.

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