High-frequency rectification output series-parallel dynamic hot switching circuit and switching method

Abstract

The invention discloses a high-frequency rectification output series-parallel dynamic thermal switching circuit and a switching method in the technical field of switching circuits, and the circuit comprises at least two groups of transformers, a full-bridge rectification unit and a change-over switch, each group of transformer is provided with a primary winding and at least two secondary windings, the number of the full-bridge rectification units is the same as that of the secondary windings in each group of transformers, the secondary windings in each group of transformers are mutually independent, each secondary winding is electrically connected to each full-bridge rectification unit, and a change-over switch is arranged between at least one secondary winding in each group of transformers and the full-bridge rectification unit; all the full-bridge rectification units are electrically connected through the change-over switches, series-parallel connection switching among all the full-bridge rectification units is achieved, under the condition that output current and voltage are not interrupted, series-parallel connection switching of an output loop is achieved, meanwhile, the voltage withstanding requirement of an output capacitor is lowered, the service life of the capacitor is prolonged, and cost is reduced.

Description

Technical Field

[0001] The invention relates to a high-frequency rectifier output series-parallel dynamic hot switching circuit and a switching method, belonging to the technical field of switching circuits. Background Art

[0002] In the field of industrial power supply, LLC resonant converter converts the input DC voltage into high-frequency AC voltage through an inverter, and obtains a stable DC voltage at the output end after rectification by the resonant network and transformer. In LLC resonant converter, the equivalent parameters of the resonant network can be adjusted by changing the connection mode of the resonant element or circuit through the series-parallel switching circuit, thereby affecting the voltage gain of the converter. Due to the high operating frequency, it will bring a series of characteristics different from low-frequency rectification. For example, the influence of parasitic capacitance on circuit performance becomes more significant at high frequency.

[0003] Therefore, in the conventional design of series-parallel switching circuits, in order to meet the voltage adaptation in different series-parallel modes, output capacitors with extremely high withstand voltage values ​​have to be selected, which directly leads to a significant increase in capacitor costs; moreover, due to the high withstand voltage requirements, the size and weight of the capacitors also increase, which becomes a serious constraint for electronic devices that pursue miniaturization and lightweight, as well as systems that have requirements for spatial layout; in addition, complex circuit conditions also cause capacitors to be frequently in a high-voltage stress state, which greatly reduces the service life of the capacitors and forces frequent replacement of capacitors, further increasing the maintenance cost and downtime frequency of the equipment. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a high-frequency rectifier output series-parallel dynamic hot switching circuit and switching method, which can realize the series-parallel switching of the output circuit without interrupting the output current and voltage, while reducing the withstand voltage requirement of the output capacitor, increasing the service life of the capacitor and reducing the cost.

[0005] In order to solve the above technical problems, the present invention is implemented by adopting the following technical solutions: In the first aspect, the present invention provides a high-frequency rectifier output series-parallel dynamic hot switching circuit, including a transformer, a full-bridge rectifier unit and a switching switch, including at least two groups of transformers, each group of the transformers having a primary winding and at least two secondary windings, the number of the full-bridge rectifier units is the same as the number of secondary windings in each group of the transformers, and the secondary windings in each group of the transformers are independent of each other, each of the secondary windings is electrically connected to each full-bridge rectifier unit, and a switching switch is provided between at least one secondary winding and the full-bridge rectifier unit in each group of the transformers; the full-bridge rectifier units are electrically connected through the switching switch to achieve series-parallel switching between the full-bridge rectifier units; each full-bridge rectifier unit is respectively connected in parallel with a capacitor branch, at least one capacitor branch is connected in parallel with a discharge resistor branch, and a switching switch is provided on the discharge resistor branch.

[0006] In combination with the first aspect, optionally, the transformer includes a first transformer and a second transformer, the first transformer includes a primary winding NP1, a first secondary winding NS1 and a second secondary winding NS2, the second transformer includes a primary winding NP2, a third secondary winding NS3 and a fourth secondary winding NS4, and the full-bridge rectifier unit includes a first full-bridge rectifier unit and a second full-bridge rectifier unit.

[0007] In combination with the first aspect, optionally, the first full-bridge rectifier unit includes a diode D1, a diode D2, a diode D3 and a diode D4, the diode D1 and the diode D2 are connected in series to form a first series branch, the diode D3 and the diode D4 are connected in series to form a second series branch, and the first series branch and the second series branch are connected in parallel; the second full-bridge rectifier unit includes a diode D5, a diode D6, a diode D7 and a diode D8, the diode D5 and the diode D6 are connected in series to form a third series branch, the diode D7 and the diode D8 are connected in series to form a fourth series branch, and the third series branch and the fourth series branch are connected in parallel.

[0008] In combination with the first aspect, optionally, a switching switch S1 is connected in series between the like-name end of the first secondary winding NS1 and the diode D1 and the diode D2, and the opposite-name end of the first secondary winding NS1 is electrically connected between the diode D3 and the diode D4; the opposite-name end of the second secondary winding NS2 is electrically connected between the diode D5 and the diode D6, and the like-name end of the second secondary winding NS2 is electrically connected between the diode D7 and the diode D8; a switching switch S2 is connected in series between the like-name end of the third secondary winding NS3 and the diode D1 and the diode D2, and the opposite-name end of the third secondary winding NS3 is electrically connected between the diode D3 and the diode D4; the opposite-name end of the fourth secondary winding NS4 is electrically connected between the diode D5 and the diode D6, and the like-name end of the fourth secondary winding NS4 is electrically connected between the diode D7 and the diode D8.

[0009] In combination with the first aspect, optionally, the first full-bridge rectifier unit is connected in parallel with a capacitor C1, the second full-bridge rectifier unit is connected in parallel with a capacitor C2, the capacitor C1 is connected in parallel with a discharge resistance branch, the discharge resistance branch includes a resistor R1 and a switching switch S6 connected in series; one end of the capacitor C1 is connected to the positive electrode of the diode D9, the cathode of the diode D9 is the output terminal A1, the other end of the capacitor C2 is the output terminal A2, one end of the capacitor C2 is the output terminal B1, and the other end of the capacitor C2 is the output terminal B2; a switching switch S3 is connected in series between the output terminal A1 and the output terminal B1, a switching switch S4 is connected in series between the output terminal A2 and the output terminal B2, and a switching switch S5 is connected in series between the output terminal A2 and the output terminal B1.

[0010] In combination with the first aspect, optionally, the switching switch is at least one of a MOS tube and an IGBT.

[0011] In combination with the first aspect, optionally, the primary circuit of the transformer is one of a phase-shifted full-bridge topology circuit, a phase-shifted half-bridge topology circuit, a single-phase LLC full-bridge topology circuit, and a single-phase LLC half-bridge topology circuit.

[0012] In a second aspect, the present invention provides a method for dynamic hot switching of high-frequency rectifier output series-parallel connection, using the high-frequency rectifier output series-parallel connection dynamic hot switching circuit as described in the first aspect, the method comprising: Measure the voltage from output port A1 to output port A2, which is the voltage at output port A; Measure the voltage from output port B1 to output port B2, which is the voltage at output port B; Measure the voltage from output port A1 to output port B2, which is the output voltage of the whole machine; According to the connection status of the circuit, determine the magnitude relationship between the output voltage of the whole machine and the preset switching value; According to the judgment result, the on and off of each switching switch is controlled.

[0013] In combination with the second aspect, optionally, judging the magnitude relationship between the output voltage of the whole machine and the preset switching value according to the connection state of the circuit, and controlling the on and off of each switching switch according to the judgment result includes: When the circuit is in a parallel working state, it is determined whether the output voltage of the whole machine is greater than a first preset switching value, and if so, the parallel switching series working logic is started; When the circuit is in the series working state, it is determined whether the output voltage of the whole machine is less than the second preset switching value, and if so, the series-to-parallel working logic is started.

[0014] In combination with the second aspect, optionally, the parallel-to-series operation logic includes: Drag and open switch S1, switch S2, and switch S4 at the same time; The switching switch S6 is pulled in to discharge the output capacitor C1. After the discharge is completed, the switching switch S6 is pulled open; Pull on the switch S5, and pull off the switch S3; At the same time, switch S1 and switch S2 are closed, and the two switches are switched to the series working state. The series-to-parallel operation logic includes: Drag and open switch S1 and switch S2 at the same time; When the capacitance of C1 gradually drops to zero, the switch S3 is closed and the switch S5 is opened; Close the switch S5; At the same time, the switching switch S1 and the switching switch S2 are closed, and the switch is switched to the parallel working state.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention is provided with switching switches at the secondary winding of each transformer and at the connection of each full-bridge rectifier unit, and the series-parallel switching between each secondary winding and each full-bridge rectifier unit is realized by controlling the combined action of the switching switches. At the same time, by setting a discharge circuit and controlling the on-off timing of the switching switch, the withstand voltage requirement of the output capacitor is reduced without interrupting the output current and voltage, thereby indirectly increasing the service life of the capacitor and reducing the cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a circuit diagram of a high-frequency rectifier output series-parallel dynamic hot switching circuit according to an embodiment of the present invention; Figure 2 It is a flow chart of a method for dynamic hot switching of high-frequency rectifier output series-parallel connection according to an embodiment of the present invention. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is described in detail below through the accompanying drawings and specific embodiments. It should be understood that the embodiments of the present application and the specific features in the embodiments are detailed descriptions of the technical solution of the present application, rather than limitations on the technical solution of the present application.

[0018] In the description of the present invention, if “first” or “second” is described, it is only used for the purpose of distinguishing technical features, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0019] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0020] Embodiment 1:

[0021] like Figure 1 As shown, the present invention provides a high-frequency rectifier output series-parallel dynamic hot switching circuit, including a transformer, a full-bridge rectifier unit and a switch. In some embodiments, the switch is at least one of a MOS tube and an IGBT; at least two groups of transformers are included, each group of the transformers has a primary winding and at least two secondary windings, the number of the full-bridge rectifier units is the same as the number of the secondary windings in each group of the transformers, and in one embodiment, Figure 1 As shown, the transformer includes a first transformer and a second transformer. In some embodiments, the first transformer is a positive transformer, the second transformer is a negative transformer, the first transformer includes a primary winding NP1, a first secondary winding NS1 and a second secondary winding NS2, the second transformer includes a primary winding NP2, a third secondary winding NS3 and a fourth secondary winding NS4, and the full-bridge rectifier unit includes a first full-bridge rectifier unit and a second full-bridge rectifier unit.

[0022] The secondary windings in each group of the transformers are independent of each other, and each of the secondary windings is electrically connected to each full-bridge rectifier unit, and a switching switch is provided between at least one secondary winding and the full-bridge rectifier unit in each group of the transformers; the full-bridge rectifier units are electrically connected through the switching switch to achieve series-parallel switching between the full-bridge rectifier units; each full-bridge rectifier unit is respectively connected in parallel with a capacitor branch, and at least one capacitor branch is connected in parallel with a discharge resistor branch, and a switching switch is provided on the discharge resistor branch.

[0023] In some embodiments, the first full-bridge rectifier unit includes a diode D1, a diode D2, a diode D3 and a diode D4, the diode D1 and the diode D2 are connected in series to form a first series branch, the diode D3 and the diode D4 are connected in series to form a second series branch, and the first series branch and the second series branch are connected in parallel; the second full-bridge rectifier unit includes a diode D5, a diode D6, a diode D7 and a diode D8, the diode D5 and the diode D6 are connected in series to form a third series branch, the diode D7 and the diode D8 are connected in series to form a fourth series branch, and the third series branch and the fourth series branch are connected in parallel.

[0024] A switching switch S1 is connected in series between the like-name end of the first secondary winding NS1 and the diode D1 and the diode D2, and the opposite-name end of the first secondary winding NS1 is electrically connected between the diode D3 and the diode D4; the opposite-name end of the second secondary winding NS2 is electrically connected between the diode D5 and the diode D6, and the like-name end of the second secondary winding NS2 is electrically connected between the diode D7 and the diode D8; a switching switch S2 is connected in series between the like-name end of the third secondary winding NS3 and the diode D1 and the diode D2, and the opposite-name end of the third secondary winding NS3 is electrically connected between the diode D3 and the diode D4; the opposite-name end of the fourth secondary winding NS4 is electrically connected between the diode D5 and the diode D6, and the like-name end of the fourth secondary winding NS4 is electrically connected between the diode D7 and the diode D8.

[0025] The first full-bridge rectifier unit is connected in parallel with a capacitor C1, and the second full-bridge rectifier unit is connected in parallel with a capacitor C2. The capacitor C1 is connected in parallel with a discharge resistance branch, and the discharge resistance branch includes a resistor R1 and a switch S6 connected in series. The capacitor C1, the resistor R1 and the switch S6 constitute a discharge circuit. When the switch S6 is closed, the discharge circuit works, and when the switch S6 is disconnected, the discharge circuit stops working. One end of the capacitor C1 is connected to the positive electrode of the diode D9, and the cathode of the diode D9 is the output terminal A1. The other end of the capacitor C2 is the output terminal A2. One end of capacitor C2 is output terminal B1, and the other end of capacitor C2 is output terminal B2; a switching switch S3 is connected in series between output terminal A1 and output terminal B1, a switching switch S4 is connected in series between output terminal A2 and output terminal B2, and a switching switch S5 is connected in series between output terminal A2 and output terminal B1; the positive pole of output port A is output terminal A1, and the negative pole of output port A is output terminal A2; the positive pole of output port B is output terminal B1, and the negative pole of output port B is output terminal B2; the positive pole of the output terminal of the whole machine is output port A1, and the negative pole of the output terminal of the whole machine is output port B2.

[0026] In some embodiments, the primary circuit of the transformer is one of a phase-shifted full-bridge topology circuit, a phase-shifted half-bridge topology circuit, a single-phase LLC full-bridge topology circuit, and a single-phase LLC half-bridge topology circuit.

[0027] Embodiment 2:

[0028] like Figure 2 As shown, the present invention provides a high-frequency rectifier output series-parallel dynamic hot switching method, using the high-frequency rectifier output series-parallel dynamic hot switching circuit as described in Example 1, the method includes: Measure the voltage from output port A1 to output port A2, which is the voltage at output port A; Measure the voltage from output port B1 to output port B2, which is the voltage at output port B; Measure the voltage from output port A1 to output port B2, which is the output voltage of the whole machine; According to the connection status of the circuit, determine the magnitude relationship between the output voltage of the whole machine and the preset switching value; According to the judgment result, the on and off of each switching switch is controlled.

[0029] When the circuit is in a parallel working state, at this time, the switching switches S1, S2, S3 and S4 are closed, and the switching switches S5 and S6 are opened. At this time, the output port A1 is short-circuited with the output port B1, and the output port A2 is short-circuited with the output port B2, that is, the output port A and the output port B are output in parallel; at this time, it is determined whether the output voltage of the whole machine is greater than the first preset switching value. In some embodiments, the first preset switching value is half of the maximum output voltage plus the bias voltage. The specific value of the bias voltage depends on the gain curve of the resonant circuit. In one embodiment, the bias voltage is 10V; if the output voltage of the whole machine is greater than the first preset switching value, the parallel switching series working logic is started.

[0030] The parallel and series working logic includes: Drag and open switch S1, switch S2, and switch S4 at the same time; The switch S6 is pulled in to discharge the output capacitor C1. After the discharge is completed, the switch S6 is pulled open. In some embodiments, the method for determining that the discharge of the capacitor C1 is completed is to determine whether the voltage at the output port A is lower than a preset voltage. In one embodiment, the preset voltage is 10V. Pull on the switch S5, and pull off the switch S3; At the same time, the switching switch S1 and the switching switch S2 are closed, and the two switches are switched to the series working state.

[0031] When the circuit is in the series working state, at this time, the switching switches S1 and S2 are closed, the switching switches S3, S4, and S6 are disconnected, and the switching switch S5 is closed. At this time, the output port A2 and the output port B1 are short-circuited, that is, the output port A and the output port B are output in series; at this time, it is determined whether the output voltage of the whole machine is greater than the second preset switching value. In some embodiments, the second preset switching value is half of the maximum output voltage minus the bias voltage. The specific value of the bias voltage depends on the gain curve of the resonant circuit. In one embodiment, the bias voltage is 10V; it is determined whether the output voltage of the whole machine is less than the second preset switching value. If so, the series switching parallel working logic is started.

[0032] The series and parallel working logic includes: At the same time, open the switch S1 and the switch S2. At this time, the voltage across the capacitor C1 is discharged through the output load. When the voltage of the capacitor C1 gradually drops, the voltage of the capacitor C2 gradually rises, keeping the output voltage of the whole machine unchanged. When the capacitance C1 gradually drops to zero, the switch S3 is pulled in and the switch S5 is pulled out. At this time, the output port B outputs alone and the output port A has no energy output. In some embodiments, the voltage at the output port A is used to determine whether the capacitance C1 drops to zero. When the voltage at the output port A is lower than the preset voltage, it is determined that the capacitance C1 drops to zero. The switch S5 is pulled in, and the output port A and the output port B are in parallel. At the same time, due to the presence of the anti-reverse connection diode D9, there will be no surge current; The switching switch S1 and the switching switch S2 are simultaneously closed, and the output port A and the output port B output energy at the same time, and the system is switched to a parallel working state.

[0033] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A high-frequency rectifier output series-parallel dynamic hot switching circuit, comprising a transformer, a full-bridge rectifier unit and a switch, characterized in that: At least two groups of transformers are included, each group of transformers has a primary winding and at least two secondary windings, the number of full-bridge rectifier units is the same as the number of secondary windings in each group of transformers, and the secondary windings in each group of transformers are independent of each other, each secondary winding is electrically connected to each full-bridge rectifier unit, and a switching switch is provided between at least one secondary winding and the full-bridge rectifier unit in each group of transformers; the full-bridge rectifier units are electrically connected through the switching switch to achieve series-parallel switching between the full-bridge rectifier units; each full-bridge rectifier unit is respectively connected in parallel with a capacitor branch, at least one capacitor branch is connected in parallel with a discharge resistor branch, and a switching switch is provided on the discharge resistor branch.

2. The high-frequency rectifier output series-parallel dynamic hot switching circuit according to claim 1 is characterized in that: The transformer includes a first transformer and a second transformer, the first transformer includes a primary winding NP1, a first secondary winding NS1 and a second secondary winding NS2, the second transformer includes a primary winding NP2, a third secondary winding NS3 and a fourth secondary winding NS4, and the full-bridge rectifier unit includes a first full-bridge rectifier unit and a second full-bridge rectifier unit.

3. The high-frequency rectifier output series-parallel dynamic hot switching circuit according to claim 2 is characterized in that: The first full-bridge rectifier unit includes a diode D1, a diode D2, a diode D3 and a diode D4, the diode D1 and the diode D2 are connected in series to form a first series branch, the diode D3 and the diode D4 are connected in series to form a second series branch, and the first series branch and the second series branch are connected in parallel; the second full-bridge rectifier unit includes a diode D5, a diode D6, a diode D7 and a diode D8, the diode D5 and the diode D6 are connected in series to form a third series branch, the diode D7 and the diode D8 are connected in series to form a fourth series branch, and the third series branch and the fourth series branch are connected in parallel.

4. The high-frequency rectifier output series-parallel dynamic hot switching circuit according to claim 3 is characterized in that: A switching switch S1 is connected in series between the same-name end of the first secondary winding NS1 and the diode D1 and the diode D2, and the opposite-name end of the first secondary winding NS1 is electrically connected between the diode D3 and the diode D4; the opposite-name end of the second secondary winding NS2 is electrically connected between the diode D5 and the diode D6, and the same-name end of the second secondary winding NS2 is electrically connected between the diode D7 and the diode D8; a switching switch S2 is connected in series between the same-name end of the third secondary winding NS3 and the diode D1 and the diode D2, and the opposite-name end of the third secondary winding NS3 is electrically connected between the diode D3 and the diode D4; the opposite-name end of the fourth secondary winding NS4 is electrically connected between the diode D5 and the diode D6, and the same-name end of the fourth secondary winding NS4 is electrically connected between the diode D7 and the diode D8.

5. The high-frequency rectifier output series-parallel dynamic hot switching circuit according to claim 2 or 4, characterized in that: The first full-bridge rectifier unit is connected in parallel with a capacitor C1, and the second full-bridge rectifier unit is connected in parallel with a capacitor C2. The capacitor C1 is connected in parallel with a discharge resistance branch, and the discharge resistance branch includes a resistor R1 and a switch S6 connected in series; one end of the capacitor C1 is connected to the positive electrode of the diode D9, and the cathode of the diode D9 is the output terminal A1, the other end of the capacitor C2 is the output terminal A2, one end of the capacitor C2 is the output terminal B1, and the other end of the capacitor C2 is the output terminal B2; a switch S3 is connected in series between the output terminal A1 and the output terminal B1, a switch S4 is connected in series between the output terminal A2 and the output terminal B2, and a switch S5 is connected in series between the output terminal A2 and the output terminal B1.

6. The high-frequency rectifier output series-parallel dynamic hot switching circuit according to claim 1, characterized in that: The switching switch is at least one of a MOS tube and an IGBT.

7. The high-frequency rectifier output series-parallel dynamic hot switching circuit according to claim 1, characterized in that: The primary circuit of the transformer is one of a phase-shifted full-bridge topology circuit, a phase-shifted half-bridge topology circuit, a single-phase LLC full-bridge topology circuit, and a single-phase LLC half-bridge topology circuit.

8. A method for dynamic hot switching of high-frequency rectifier output series-parallel connection, using the high-frequency rectifier output series-parallel connection dynamic hot switching circuit as claimed in claim 5, characterized in that: The method comprises: Measure the voltage from output port A1 to output port A2, which is the voltage at output port A; Measure the voltage from output port B1 to output port B2, which is the voltage at output port B; Measure the voltage from output port A1 to output port B2, which is the output voltage of the whole machine; According to the connection status of the circuit, determine the magnitude relationship between the output voltage of the whole machine and the preset switching value; According to the judgment result, the on and off of each switching switch is controlled.

9. The high-frequency rectifier output series-parallel dynamic hot switching method according to claim 8, characterized in that: The step of judging the magnitude relationship between the output voltage of the whole machine and the preset switching value according to the connection state of the circuit, and controlling the on and off of each switching switch according to the judging result comprises: When the circuit is in a parallel working state, it is determined whether the output voltage of the whole machine is greater than a first preset switching value, and if so, the parallel switching series working logic is started; When the circuit is in the series working state, it is determined whether the output voltage of the whole machine is less than the second preset switching value, and if so, the series-to-parallel working logic is started.

10. The method for dynamic hot switching of high-frequency rectifier output series-parallel connection according to claim 9, characterized in that: The parallel-to-series operation logic includes: Drag and open switch S1, switch S2, and switch S4 at the same time; The switching switch S6 is pulled in to discharge the output capacitor C1. After the discharge is completed, the switching switch S6 is pulled open; Pull on the switch S5, and pull off the switch S3; At the same time, switch S1 and switch S2 are closed, and the two switches are switched to the series working state. The series-to-parallel operation logic includes: Drag and open switch S1 and switch S2 at the same time; When the capacitance of C1 gradually drops to zero, the switch S3 is closed and the switch S5 is opened; Close the switch S5; At the same time, the switching switch S1 and the switching switch S2 are closed, and the switch is switched to the parallel working state.

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