LLC topology control method for ultra-wide output voltage of magnetic stimulation instrument

Abstract

The application discloses an LLC topology control method for a super-wide output voltage of a magnetic stimulation instrument, and belongs to the technical field of power charging. After the primary side winding of a transformer and the secondary side winding of the transformer are modified, the turns ratio of the secondary side of the transformer to the primary side is changed by controlling switches, and then the range of the output gain of the transformer is changed; the output gain of the transformer is divided according to the control logic of the primary side winding of the transformer and the secondary side winding of the transformer; the calculation formula of the output voltage gain is adjusted to obtain a simplified calculation formula of the output voltage gain; the output gain range of the divided transformer is analyzed respectively, the parameter value in the output voltage gain formula is selected according to the output voltage range, the frequency change range under different output gain ranges is obtained; and according to the modification and analysis of the transformer, the specific control process of the improved LLC topology circuit for charging is obtained.

Description

Technical Field

[0001] This invention relates to the field of power supply and charging technology, specifically to an LLC topology control method for an ultra-wide output voltage magnetic stimulator. Background Technology

[0002] With the rapid development of science and technology, the medical system has also been greatly improved. Modern medicine features a wide variety of automated instruments and equipment. Operators use the coordination of different instruments to treat patients. Among these, magnetic stimulators are extremely widely used. A magnetic stimulator mainly consists of a high-voltage power supply, a pulse capacitor, and a magnetic coil. The basic working process is as follows: the high-voltage power supply charges the pulse capacitor. After reaching the target voltage, the high-voltage power supply is turned off and the charging switch is disconnected. When the discharge switch is turned on, the high-voltage pulse power supply instantly releases the high energy stored during charging into the magnetic coil, generating a huge current in the magnetic coil within a very short time, thus creating a strong pulsed magnetic field around the magnetic coil. By setting different frequencies and intensities, different treatment plans can be output, achieving therapeutic goals for different populations and different diseases in medicine.

[0003] Magnetic stimulators typically require setting different intensity levels (1% to 100%), and the corresponding pulse capacitors are charged to different voltage levels by a high-voltage power supply; at a certain intensity level, the pulse capacitors will charge from a higher voltage U... H Discharge to a lower voltage U L The high-voltage power supply will transfer the pulse capacitor from a lower voltage U L Charge to a higher voltage U H Throughout the process, the output voltage of the high-voltage power supply will vary within a wide range, thus requiring the output of the high-voltage power supply to meet a wide voltage gain range.

[0004] To meet the output voltage requirements of the aforementioned magnetic stimulator and considering high-voltage electrical isolation, the output stage DC / DC converter of the high-voltage power supply needs to be isolated. Currently, the industry commonly uses a phase-shifted full-bridge converter to achieve the required high-voltage gain variation range. The inherent limitations and design challenges of a phase-shifted full-bridge converter are as follows:

[0005] 1) When its output voltage and power vary over a wide load range, it is difficult to achieve soft switching across the entire load range. This is mainly because it is difficult to achieve ZVS of the primary side MOS of the transformer under light load, which leads to a decrease in charging conversion efficiency.

[0006] 2) The voltage stress when the secondary-side switch of the phase-shifted full-bridge is turned off is relatively high. The greater the stimulation intensity, the greater the output voltage of the phase-shifted full-bridge. At the same time, it will lead to a greater voltage stress on the secondary-side switch. Therefore, it is necessary to use a switch with a higher rated voltage, or to use multiple switches in series, and at the same time, connect an absorption circuit in parallel across the switch to meet the voltage stress, which ultimately leads to a reduction in charging conversion efficiency.

[0007] This invention employs a full-bridge LLC that is easy to achieve ZVS across the entire load range and has low turn-off voltage stress on the secondary-side switching transistors. To overcome the narrow output voltage gain of the full-bridge LLC, the improved full-bridge LLC topology and control method proposed in this invention can meet the wide range of output voltage gain variations. Summary of the Invention

[0008] The purpose of this invention is to provide an LLC topology control method for an ultra-wide output voltage of a magnetic stimulator, so as to solve the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0010] An LLC topology control method for an ultra-wide output voltage magnetic stimulator, the method comprising the following steps:

[0011] S1. After modifying the primary winding and secondary winding of the transformer, the turns ratio between the secondary and primary windings of the transformer is changed by controlling the switch, thereby changing the range of the transformer output gain.

[0012] The components of an LLC power circuit include, for example: Figure 6 As shown, the circuit includes a full-bridge switching network composed of switching transistors Q1 to Q4, an LLC transformer, a resonant inductor, a resonant capacitor, output uncontrolled full-bridge rectifier network 1 and output uncontrolled full-bridge rectifier network 2, and a filter capacitor C. P1 and C P2 Charging switch Kc and pulse capacitor C pulse .

[0013] The current is output from the left side, and there is a resonant capacitor connected in parallel with the full-bridge switching network consisting of switching transistors Q1 to Q4. The primary side of the transformer consists of a capacitor and a resonant inductor L. re The transformer secondary side consists of two windings, CB and CB. Each winding is connected to an H-bridge consisting of four diodes. These two H-bridges are output uncontrolled full-bridge rectifier network 1 and output uncontrolled full-bridge rectifier network 2, respectively, and are connected by a switch K. s Controlled two uncontrolled full-bridge rectifier networks in series, K p1 and K p2 The two uncontrolled full-bridge rectifier networks are connected in series and parallel, and the charging switch K is used. c With Kp1 Series connection, pulse capacitor C pulse With K p1 and K p2 They are connected in parallel, and the final output current is obtained.

[0014] The output voltage range switching switch includes K on the primary side of the transformer. d and K on the secondary side of the transformer p1 and K p2 Point A is the neutral tap between the primary windings CB and CB of the transformer. The input U of LLC... BUS The PFC circuit in the preamplifier stage converts the input AC voltage into a stable DC bus voltage. The LLC power circuit adjusts the voltage gain of the full-bridge switching transistors by regulating their operating frequency, thereby regulating the range of its output voltage. The minimum value of the LLC circuit's switching frequency range cannot allow it to enter the capacitive region, while the maximum value is limited by the switching losses of the power devices and the turn-on and turn-off times of the switching transistors. Furthermore, it needs to achieve near-zero voltage switching (ZVS). These factors result in the maximum adjustable range of its output voltage gain typically being around 2 to 3 times.

[0015] Modifications are made to the primary and secondary windings of the transformer. Specific modification methods are as follows: Figure 6 As shown:

[0016] Suppose that the primary winding of the transformer has terminals C and B, with a center tap A leading out from the middle, and the number of turns between C and A is N. A The number of turns between CB is N A +N B By switching K d Switching between connecting winding node A or B to the resonant cavity changes the turns ratio between the secondary and primary sides of the transformer, thereby altering the transformer's output gain range.

[0017] The two windings on the secondary side of the transformer use switch K s K p1 With K p2 By controlling the series or parallel connection of the rectified voltages of the two output windings, the output voltage gain range is expanded to twice its original value.

[0018] S2. Based on the control logic of the primary winding and the secondary winding of the transformer, divide the output gain of the transformer.

[0019] Let the maximum range of the output voltage on the high-voltage power supply be U. cmin ~U cmax The output power is P o The maximum output current is I. o_maxThe input bus voltage is U bus The resonant inductance is L re The resonant capacitance is C re The magnetizing inductance between the primary windings CB of the transformer is L. CB The number of turns between the primary windings CB of the transformer is N. A +N B The number of turns between CA on the primary side of the transformer is N. A ;

[0020] From the known circuit parameters above, we can obtain: the magnetizing inductance L between CA. CA for

[0021]

[0022] Resonant frequency f r for

[0023]

[0024] The ratio K between the magnetizing inductance and the resonant inductance of the primary winding CB of the transformer CB for

[0025]

[0026] The ratio K between the magnetizing inductance and the resonant inductance of the primary winding CA of the transformer CA for

[0027]

[0028] By combining the control logic of the primary and secondary side switches of the transformer, four different gain range combination modes can be formed, which will increase the output voltage range U. cmin ~U cmax The system is divided into four corresponding intervals, as shown in the table below:

[0029]

[0030] S3. Adjust the calculation formula for output voltage gain to obtain a simplified calculation formula for output voltage gain;

[0031] For the LLC topology, the voltage gain of the LLC resonant converter is analyzed using the fundamental component analysis method. The output voltage gain formula can be simplified to:

[0032]

[0033] In the formula f s f is the switching frequency. r I is the resonant frequency. o For the LLC output current, UBUS The input bus voltage of the LLC is denoted by m, where m is the output series coefficient, and m is the ratio of the magnetizing inductance to the resonant inductance. Characteristic impedance Turns ratio of the primary winding to the secondary winding of the transformer N1 is the number of turns in the primary winding of the transformer, N2 is the number of turns in the secondary winding of the transformer, L m L is the magnetizing inductance of the transformer. re For resonant inductance, C re It is a resonant capacitor.

[0034] S4. Analyze the output gain range of the divided transformers respectively, select the parameter value in the output voltage gain formula according to the output voltage range, and obtain the frequency variation range under different output gain ranges.

[0035] For output voltage range in [U cmin U c1 ) is analyzed, when the output voltage range is [U cmin U c1 When K d Connect to B, disconnect from K s Close K p1 and K p2 At that time, N1 = N in the output voltage gain formula A +N B L m The magnetizing inductance L between the primary windings CB of the transformer CB The ratio K is K CB The two windings on the secondary side of the transformer are connected in parallel, with an output series coefficient m = 1, and the total output voltage U 尸 The voltage is the same as the voltage after rectification of a single secondary output winding; N1, L CB K CB Substituting into the simplified formula for output voltage gain, and plotting the output voltage gain frequency curve, as shown... Figure 2 As shown;

[0036] Let U c_1st (K, f) s U cmin I o_max ) is at voltage U cmin The output current is the maximum I. o_max The curve showing the change of output voltage with frequency; U c_1st (K, f) s U c1 P o_max / U c1 ) is at voltage U c1 The output current is the maximum load P. o_maxDivide by the output voltage U c1 The curve showing the change of output voltage with frequency; U res_1st (K, f) s The curve showing the voltage versus frequency when the resonant network is purely resistive is shown; U c1_set (f s The output voltage is U. c1 The curve of time, U cmin_set (f s The output voltage is U. cmin The curve at time;

[0037] Assume the working region is located at the purely resistive boundary line U. res_1st (K, f) s Within the sensory region on the right, U c_1st (K, f) s U cmin I o_max ) and U cmin_set (f s The output voltage U is obtained at the intersection of the inductive regions. cmin The operating frequency is f1kHz; U c_1st (K, f) s U c1 P o_max / U c1 ) and U c1_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The operating frequency is f2kHz; when the output voltage is in [U cmin U c1 When the frequency changes, the range of frequency change is f1kHz to f2kHz.

[0038] For output voltage range in [U c1 U c2 ) is analyzed, when the output voltage range is [U c1 U c2 When K d Connect to A, disconnect from K s Close K p1 and K p2 The number of turns in the primary winding of the transformer is N1 = N A , and the output voltage range is in [U cmin U c1 Compared to the previous method, the number of turns in the primary winding of the transformer is reduced, resulting in a smaller turns ratio N and consequently a larger output voltage gain; the magnetizing inductance of the primary winding of the transformer is reduced to L. CA This makes the ratio K between the magnetizing inductance and the resonant inductance of the primary winding of the transformer... CAAs N decreases, the slope of the frequency gain curve increases, resulting in a larger output voltage gain range within the same frequency range; A L CA K CA Substituting into the simplified formula for output voltage gain, plot the gain-frequency curve, as follows: Figure 3 As shown;

[0039] Let U c_2nd (K CA f s U c1 P o_max / U c1 ) is the voltage U c1 The output current is the maximum load P. o_max Divide by the output voltage U c1 The curve of output voltage versus frequency, U c_2nd (K CA f s U c2 P o_max / U c2 ) is the voltage U c2 The output current is the maximum load P. o_max Divide by the output voltage U c2 The curve of output voltage versus frequency, U res_2nd (K CA f s U is the voltage versus frequency curve when the resonant network is purely resistive. c1R_set (f s The output voltage is U. c1 The curve of time, U c2_set (f s The output voltage is U. c2 The curve at time;

[0040] Assume the working region is located at the purely resistive boundary line U. res_2nd (K CA f s The right-hand sensory region; U c_2nd (K CA f s U c1 P o_max / U c1 ) and U c1R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The corresponding operating frequency is f3kHz; U c_2nd (K CA f s U c2 P o_max / U c2) and U c2_set (f s The output voltage U is obtained at the intersection of the inductive regions. c2 The corresponding operating frequency is f4kHz. When the output voltage is in [U... c1 U c2 When the frequency changes, the range of frequency change is f3kHz to f4kHz.

[0041] For output voltage range in [U c2 U c3 ) is analyzed, when the output voltage range is [U c2 U c3 When K d Join to B, close K s Disconnect K p1 and K p2 The number of turns in the primary winding of the transformer is N1 = N A +N B The two output windings are connected in series after rectification, and the output voltage U 尸 The voltage is twice the rectified voltage of a single output winding, and the output series coefficient m = 2. N1, L CB K CB Substituting m into the simplified formula for output voltage gain, and plotting the gain-frequency curve, as shown... Figure 4 As shown;

[0042] Let U c_3rd (K, f) s U c2 P o_max / U c2 ) is the voltage U c2 The output current is the maximum load P. o_max Divide by the output voltage U c2 The curve of output voltage versus frequency, U c_3rd (K, f) s U c3 P o_max / U c3 ) is the voltage U c3 The output current is the maximum load P. o_max Divide by the output voltage U c3 The curve of output voltage versus frequency, U res_3rd (K, f) s U is the voltage versus frequency curve when the resonant network is purely resistive. c2R_set (f s The output voltage is U. c2 The curve of time, U c3_set (f s The output voltage is U. c3 The curve at time;

[0043] Assume the working region is located at the purely resistive boundary line U. res_3rd (K, f) s The right-hand sensory region; U c_3rd (K, f) s U c2 P o_max / U c2 ) and U c2R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c2 The corresponding operating frequency is f5kHz; U c_3rd (K, f) s U c3 P o_max / U c3 ) and U c3_set (f s The output voltage U is obtained at the intersection of the inductive regions. c3 The corresponding operating frequency is f6kHz;

[0044] When the output voltage is in [U c1 U c2 When the frequency changes, the range of frequency change is f5kHz to f6kHz.

[0045] For output voltage range in [U c3 U cmax ] Analyze the output voltage range when it is within [U c3 U cmax At that time, K d Join to A, close K s Disconnect K p1 and K p2 As the transformer turns ratio N decreases, the magnetizing inductance L... m The output voltage decreases, the two output windings are connected in series, the output series coefficient m = 2, and the output voltage range is within [U c1 U c2 ) and [U c2 U c3 The control method in ) increases the output voltage gain range, thus increasing N A L CA K CA Substituting m into the simplified formula for output voltage gain, and plotting the gain-frequency curve, as shown... Figure 5 As shown;

[0046] Let U c_4th (K CA f s U c3 P o_max / U c3 ) is the voltage Uc3 The output current is the maximum load P. o_max Divide by the output voltage U c3 The curve of output voltage versus frequency, U c_4th (K CA f s U c4 P o_max / U c4 ) is the voltage U c4 The output current is the maximum load P. o_max Divide by the output voltage U c4 The curve of output voltage versus frequency, U res_4th (K CA f s U is the voltage versus frequency curve when the resonant network is purely resistive. c3R_set (f s The output voltage is U. c3 The curve of time, U c4_set (f s The output voltage is U. c4 The curve at time;

[0047] Assume the working region is located at the purely resistive boundary line U. res_4th (K CA f s The right-hand sensory region; U c_4th (K CA f s U c3 P o_max / U c3 ) and U c3R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c3 The corresponding operating frequency is f7kHz; U c_4th (K CA f s U c4 P o_max / U c4 ) and U c4_set (f s The output voltage U is obtained at the intersection of the inductive regions. c4 The corresponding operating frequency is f8kHz; when the output voltage is in [U c3 U cmax When the frequency changes, the range is f7kHz to f a kHz.

[0048] By analyzing the four output voltage gain ranges [U] cmin U c1 ), [U c1 Uc2 ), [U c2 U c3 ) and [U c3 U cmax The calculation and analysis yielded eight frequency values ​​{f1, f2, f3...f8}. These eight frequency values ​​were compared and arranged in ascending order. The smallest value was set as f. min The maximum value is f max Switching is achieved through the primary and secondary switches of the LLC transformer, within the frequency variation range (f min ~f max Within fr, an ultra-wide adjustment range of up to 10 times the maximum / minimum output voltage gain can be achieved.

[0049] S5. Based on the modification and analysis of the transformer, the specific control flow for charging the improved LLC topology circuit is obtained. The specific steps are as follows: Figure 1 As shown:

[0050] S501. After starting the entire system, the operator sets the intensity level through the host computer software and transmits the intensity value L to the lower-level computer via communication. The lower-level computer MCU obtains the target charging voltage value U based on the intensity-charging voltage meter pre-stored in its memory. c ;

[0051] S502, lower-level MCU controls the target charging voltage value U c Make a judgment within the four threshold ranges [U] cmin U c1 ), [U c1 U c2 ), [U c2 U c3 ) and [U c3 U cmax Select from the options and determine the target charging voltage value U. c After specifying the threshold range, for switch K d K s K p1 K p2 After the MCU performs the corresponding control and switches the output gain selection switch, it closes the output charging control switch K. c Enter the control sequence for starting charging;

[0052] S503, First, the pulse capacitor voltage is charged to the voltage value U via soft start. c_ss After the soft start is completed, the pulse capacitor voltage is charged to the target voltage value U using a constant current followed by a constant power method. 尸 ;

[0053] S504, When charged to the target voltage value U cAfter the power supply stops working, disconnect the charging control switch K. c ;

[0054] After the S505 pulse capacitor discharges the magnetic coil, the high-voltage power supply repeats the above charging process according to the host computer settings, and so on; when the target voltage U... 尸 If the error is not within these four threshold ranges, the lower-level MCU will directly return the error to the upper-level MCU.

[0055] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0056] 1. Compared with the phase-shifted full-bridge (PSFB), the full-bridge LLC can better achieve soft switching across the entire load range and can reduce the voltage stress when the secondary-side switching transistors are turned off.

[0057] 2. This invention can significantly reduce the voltage rating of a single switching transistor on the secondary side by switching the rectified voltage in series and parallel on the secondary side of the transformer.

[0058] 3. Compared with ordinary full-bridge LLC, this invention can significantly widen the range of output voltage variation by switching the number of turns in the primary winding of the transformer and switching the series and parallel voltages after rectification on the secondary side of the transformer. Attached Figure Description

[0059] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings:

[0060] Figure 1 This invention relates to an LLC topology control method for an ultra-wide output voltage in a magnetic stimulator, which employs an improved LLC topology circuit for the pulse capacitor.

[0061] Figure 2 The present invention discloses an LLC topology control method for an ultra-wide output voltage range of a magnetic stimulator, wherein the output voltage range is [U...]. cmin U c1 Gain-frequency curve at time ( );

[0062] Figure 3 The present invention discloses an LLC topology control method for an ultra-wide output voltage range of a magnetic stimulator, wherein the output voltage range is [U...]. c1 U c2 Gain-frequency curve at time ( );

[0063] Figure 4 The present invention discloses an LLC topology control method for an ultra-wide output voltage range of a magnetic stimulator, wherein the output voltage range is [U...]. c2 U ca Gain-frequency curve at time ( );

[0064] Figure 5 The present invention discloses an LLC topology control method for an ultra-wide output voltage range of a magnetic stimulator, wherein the output voltage range is [U...]. c3 U cmax Gain-frequency curve at [time];

[0065] Figure 6 This is an improved LLC topology diagram of an LLC topology control method for an ultra-wide output voltage magnetic stimulator according to the present invention. Detailed Implementation

[0066] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] Please see Figure 1-6 The present invention provides the following technical solution:

[0068] An LLC topology control method for an ultra-wide output voltage magnetic stimulator, the method comprising the following steps:

[0069] S1. After modifying the primary winding and secondary winding of the transformer, the turns ratio between the secondary and primary windings of the transformer is changed by controlling the switch, thereby changing the range of the transformer output gain.

[0070] Modifications are made to the primary and secondary windings of the transformer. Specific modification methods are as follows: Figure 6 As shown:

[0071] Suppose that the primary winding of the transformer has terminals C and B, with a center tap A leading out from the middle, and the number of turns between C and A is N. A The number of turns between CB is N A +N B By switching K d Switching between connecting winding node A or B to the resonant cavity changes the turns ratio between the secondary and primary sides of the transformer, thereby altering the transformer's output gain range.

[0072] The two windings on the secondary side of the transformer use switch K s K p 1 and K p2 By controlling the series or parallel connection of the rectified voltages of the two output windings, the output voltage gain range is expanded to twice its original value.

[0073] S2. Based on the control logic of the primary winding and the secondary winding of the transformer, the output gain of the transformer is divided.

[0074] The output gain of the transformer is divided according to the control logic of the primary winding and the secondary winding of the transformer;

[0075] Let the maximum range of the output voltage on the high-voltage power supply be U. cmin ~U cmax The output power is P o The maximum output current is I. o_max The input bus voltage is U bus The resonant inductance is L re The resonant capacitance is C re The magnetizing inductance between the primary windings CB of the transformer is L. CB The number of turns between the primary windings CB of the transformer is N. A +N B The number of turns between CA on the primary side of the transformer is N. A ;

[0076] From the known circuit parameters above, we can obtain: the magnetizing inductance L between CA. CA for

[0077]

[0078] Resonant frequency f r for

[0079]

[0080] The ratio K between the magnetizing inductance and the resonant inductance of the primary winding CB of the transformer CB for

[0081]

[0082] The ratio K between the magnetizing inductance and the resonant inductance of the primary winding CA of the transformer CA for

[0083]

[0084] By combining the control logic of the primary and secondary side switches of the transformer, four different gain range combination modes can be formed, which will increase the output voltage range U. cmin ~U cmax The system is divided into four corresponding intervals, as shown in the table below:

[0085]

[0086] S3. Adjust the formula for calculating the output voltage gain to obtain a simplified formula. For the LLC topology, use the fundamental component analysis method to analyze the voltage gain of the LLC resonant converter. The output voltage gain formula can be simplified to:

[0087]

[0088] In the formula f s f is the switching frequency. r I is the resonant frequency. o For the LLC output current, U BUS The input bus voltage of the LLC is denoted by m, where m is the output series coefficient, and m is the ratio of the magnetizing inductance to the resonant inductance. Characteristic impedance Turns ratio of the primary winding to the secondary winding of the transformer N1 is the number of turns in the primary winding of the transformer, N2 is the number of turns in the secondary winding of the transformer, L m L is the magnetizing inductance of the transformer. re For resonant inductance, C re It is a resonant capacitor.

[0089] S4. Analyze the output gain range of the divided transformers respectively, select the parameter value in the output voltage gain formula according to the output voltage range, and obtain the frequency variation range under different output gain ranges.

[0090] For output voltage range in [U cmin U c1 ) is analyzed, when the output voltage range is [U cmin U c1 When K d Connect to B, disconnect from K s Close K p1 and K p2 At that time, N1 = N in the output voltage gain formula A +N B L m The magnetizing inductance L between the primary windings CB of the transformer CB The ratio K is K CB The two windings on the secondary side of the transformer are connected in parallel, with an output series coefficient m = 1, and the total output voltage U 尸 The voltage is the same as the voltage after rectification of a single secondary output winding; N1, L CB K CB Substituting into the simplified formula for output voltage gain, and plotting the output voltage gain frequency curve, as shown... Figure 2 As shown;

[0091] Let U c_1st (K, f)s U cmin I o_max ) is at voltage U cmin The output current is the maximum I. o_max The curve showing the change of output voltage with frequency; U c_1st (K, f) s U c1 P o_max / U c1 ) is at voltage U c1 The output current is the maximum load P. o_max Divide by the output voltage U c1 The curve showing the change of output voltage with frequency; U res_1st (K, f) s The curve showing the voltage versus frequency when the resonant network is purely resistive is shown; U c1_set (f s The output voltage is U. c1 The curve of time, U cmin_set (f s The output voltage is U. cmin The curve at time;

[0092] Assume the working region is located at the purely resistive boundary line U. res_1st (K, f) s Within the sensory region on the right, U c_1st (K, f) s U cmin I o_max ) and U cmin_set (f s The output voltage U is obtained at the intersection of the inductive regions. cmin The operating frequency is f1kHz; U c_1st (K, f) s U c1 P o_max / U c1 ) and U c1_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The operating frequency is f2kHz; when the output voltage is in [U cmin U c1 When the frequency changes, the range of frequency change is f1kHz to f2kHz.

[0093] For output voltage range in [U c1 U c2 ) is analyzed, when the output voltage range is [U c1 U c2 When K d Connect to A, disconnect from K s Close K p1and K p2 The number of turns in the primary winding of the transformer is N1 = N A , and the output voltage range is in [U cmin U c1 Compared to the previous method, the number of turns in the primary winding of the transformer is reduced, resulting in a smaller turns ratio N and consequently a larger output voltage gain; the magnetizing inductance of the primary winding of the transformer is reduced to L. CA This makes the ratio K between the magnetizing inductance and the resonant inductance of the primary winding of the transformer... CA As N decreases, the slope of the frequency gain curve increases, resulting in a larger output voltage gain range within the same frequency range; A L CA K CA Substituting into the simplified formula for output voltage gain, plot the gain-frequency curve, as follows: Figure 3 As shown;

[0094] Let U c_2nd (K CA f s U c1 P o_max / U c1 ) is the voltage U c1 The output current is the maximum load P. o_max Divide by the output voltage U c1 The curve of output voltage versus frequency, U c_2nd (K CA f s U c2 P o_max / U c2 ) is the voltage U c2 The output current is the maximum load P. o_max Divide by the output voltage U c2 The curve of output voltage versus frequency, U res_2nd (K CA f s The curve Uc represents the voltage versus frequency when the resonant network is purely resistive. 1R_set (f s The output voltage is U. c1 The curve of time, U c2_set (f s The output voltage is U. c2 The curve at time;

[0095] Assume the working region is located at the purely resistive boundary line U. res_2nd (K CA f s The right-hand sensory region; U c_2nd (K CA f s U c1P o_max / U c1 ) and U c1R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The corresponding operating frequency is f3kHz; U c_2nd (K CA f s U c2 P o_max / U c2 ) and U c2_set (f s The output voltage U is obtained at the intersection of the inductive regions. c2 The corresponding operating frequency is f4kHz. When the output voltage is in [U... c1 U c2 When the frequency changes, the range of frequency change is f3kHz to f4kHz.

[0096] For output voltage range in [U c2 U c3 ) is analyzed, when the output voltage range is [U c2 U c3 When K d Join to B, close K s Disconnect K p1 and K p2 The number of turns in the primary winding of the transformer is N1 = N A +N B The two output windings are connected in series after rectification, and the output voltage U c The voltage is twice the rectified voltage of a single output winding, and the output series coefficient m = 2. N1, L CB K CB Substituting m into the simplified formula for output voltage gain, and plotting the gain-frequency curve, as shown... Figure 4 As shown;

[0097] Let U c_3rd (K, f) s U c2 P o_max / U c2 ) is the voltage U c2 The output current is the maximum load P. o_max Divide by the output voltage U c2 The curve of output voltage versus frequency, U c_3rd (K, f) s U c3 P o_max / U c3 ) is the voltage U c3 The output current is the maximum load P. o_maxThe curve of output voltage versus frequency when divided by output voltage Uc3, U res_3rd (K, f) s U is the voltage versus frequency curve when the resonant network is purely resistive. c2R_set (f s The output voltage is U. c2 The curve of time, U c3_set (f s The curve is shown when the output voltage is Uc3;

[0098] Assume the working region is located at the purely resistive boundary line U. res_3rd (K, f) s The right-hand sensory region; U c_3rd (K, f) s U c2 P o_max / U c2 ) and U c2R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c2 The corresponding operating frequency is f5kHz; U c_3rd (K, f) s U c3 P o_max / U c3 ) and U c3_set (f s The output voltage U is obtained at the intersection of the inductive regions. c3 The corresponding operating frequency is f6kHz;

[0099] When the output voltage is in [U c1 U c2 When the frequency changes, the range of frequency change is f5kHz to f6kHz.

[0100] For output voltage range in [U c3 U cmax ] Analyze the output voltage range when it is within [U c3 U cmax At that time, K d Join to A, close K s Disconnect K p1 and K p2 With a smaller transformer turns ratio N, the magnetizing inductance Lm decreases, and the two output windings are connected in series with an output series coefficient m = 2. Combined with the output voltage range of [U... c1 U c2 ) and [U c2 U c3 The control method in ) increases the output voltage gain range, thus increasing N A L CA K CASubstituting m into the simplified formula for output voltage gain, and plotting the gain-frequency curve, as shown... Figure 5 As shown;

[0101] Let U c_4th (K CA f s U c3 P o_max / U c3 ) is the voltage U c3 The output current is the maximum load P. o_max Divide by the output voltage U c3 The curve of output voltage versus frequency, U c_4th (K CA f s U c4 P o_max / U c4 ) is the voltage U c4 The output current is the maximum load P. o_max The curve of output voltage versus frequency when divided by output voltage Uc4, U res_4th (K CA f s U is the voltage versus frequency curve when the resonant network is purely resistive. c3R_set (f s The output voltage is U. c3 The curve of time, U c4_set (f s The output voltage is U. c4 The curve at time;

[0102] Assume the working region is located at the purely resistive boundary line U. res_4th (K CA f s The right-hand sensory region; U c_4th (K CA f s U c3 P o_max / U c3 ) and U c3R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c3 The corresponding operating frequency is f7kHz; U c_4th (K CA f s U c4 P o_max / U c4 ) and U c4_set (f s The output voltage U is obtained at the intersection of the inductive regions. c4 The corresponding operating frequency is f8kHz; when the output voltage is in [Uc3 U cmax When the frequency changes, the range is f7kHz to f a kHz.

[0103] By analyzing the four output voltage gain ranges [U] cmin U c1 ), [U c1 U c2 ), [U c2 U c3 ) and [U c3 U cmax The calculation and analysis yielded eight frequency values ​​{f1, f2, f3...f8}. These eight frequency values ​​were compared and arranged in ascending order. The smallest value was set as f. min The maximum value is f max Switching is achieved through the primary and secondary switches of the LLC transformer, within the frequency variation range (f min ~f max Within this range, an ultra-wide adjustment range of up to 10 times the maximum / minimum output voltage gain can be achieved.

[0104] S5. Based on the modification and analysis of the transformer, the specific control flow for charging the improved LLC topology circuit is obtained. The specific steps are as follows: Figure 1 As shown:

[0105] S501. After starting the entire system, the operator sets the intensity level through the host computer software and transmits the intensity value L to the lower-level computer via communication. The lower-level computer MCU obtains the target charging voltage value U based on the intensity-charging voltage meter pre-stored in its memory. c ;

[0106] S502, lower-level MCU controls the target charging voltage value U c Make a judgment within the four threshold ranges [U] cmin U c1 ), [U c1 U c2 ), [U c2 U c3 ) and [U c3 U cmax After selecting from the options and determining the specific threshold range of the target charging voltage value Uc, switch K is then... d K s K p1 K p2 After the MCU performs the corresponding control and switches the output gain selection switch, it closes the output charging control switch K. c Enter the control sequence for starting charging;

[0107] S503, First, the pulse capacitor voltage is charged to the voltage value U via soft start. c_ss After the soft start is completed, the pulse capacitor voltage is charged to the target voltage value U using a constant current followed by a constant power method. 尸 ;

[0108] S504, When charged to the target voltage value U c After the power supply stops working, disconnect the charging control switch K. c ;

[0109] After the S505 pulse capacitor discharges the magnetic coil, the high-voltage power supply repeats the above charging process according to the host computer settings, and so on; when the target voltage U... 尸 If the error is not within these four threshold ranges, the lower-level MCU will directly return the error to the upper-level MCU.

[0110] Example 1

[0111] When the output voltage range is [U cmin U c1 When K d Connect to B, disconnect from K s Close K p1 and K p2 When the output voltage gain range is within the set operating region, located at the purely resistive boundary line U... res_1st (K, f) s Within the sensory region on the right, U c_1st (K, f) s U cmin I o_max ) and U cmin_set (f s The output voltage U is obtained at the intersection of the inductive regions. cmin The operating frequency is 150.5kHz; U c_1st (K, f) s U c1 P o_max / U c1 ) and U cl_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The operating frequency is 76.5kHz; when the output voltage is in [U cmin U c1 When the frequency changes, the range is 76.5kHz to 150.5kHz.

[0112] When the output voltage range is [U c1 U c2 When K d Connect to A, disconnect from K s Close K p1 and K p2Assume the working region is located at the purely resistive boundary line U. res_2nd (K CA f s The right-hand sensory region; U c_2nd (K CA f s U c1 P o_max / U c1 ) and U c1R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The corresponding operating frequency is 87.9kHz; U c_2nd (K CA f s U c2 P o_max / U c2 ) and U c2_set (f s The output voltage U is obtained at the intersection of the inductive regions. c2 The corresponding operating frequency is 72.6kHz. When the output voltage is in [U c1 U c2 When the frequency changes, the range is 72.6kHz to 87.9kHz.

[0113] When the output voltage range is [U c2 U c3 When K d Join to B, close K s Disconnect K p1 and K p2 Assume the working region is located at the purely resistive boundary line U. res_3rd (K, f) s The right-hand sensory region; U c_3rd (K, f) s U c2 P o_max / U c2 ) and U c2R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c2 The corresponding operating frequency is 79.4kHz; U c_3rd (K, f) s U c3 P o_max / U c3 ) and U c3_set (f s The output voltage U is obtained at the intersection of the inductive regions. c3 The corresponding operating frequency is 64.9kHz; when the output voltage is in [U c1 U c2When the frequency changes, the range is 64.9kHz to 79.4kHz.

[0114] When the output voltage range is [U c3 U cmax When Kd closes to A, K is closed. s Disconnect K p1 and K p2 Assume the working region is located at the purely resistive boundary line U. res_4th (K CA f s The right-hand sensory region; U c_4th (K CA f s U c3 P o_max / U c3 ) and U c3R_set (f s The output voltage U is obtained at the intersection of the inductive regions. c3 The corresponding operating frequency is 72.5kHz; U c_4th (K CA f s U c4 P o_max / U c4 ) and U c4_set (f s The output voltage U is obtained at the intersection of the inductive regions. c4 The corresponding operating frequency is 76.7kHz; when the output voltage is in [U c3 U cmax When the frequency changes, the range is 72.5kHz to 76.7kHz.

[0115] In summary, by switching the primary and secondary switches of the LLC transformer, an ultra-wide range of output voltage gain adjustment can be achieved within a relatively small frequency variation range (0.65~1.5)fr.

[0116] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0117] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An LLC topology control method for ultra-wide output voltage of a magnetic stimulator, characterized in that: The method includes the following steps: S1. After modifying the primary winding and secondary winding of the transformer, the turns ratio between the secondary and primary windings of the transformer is changed by controlling the switch, thereby changing the range of the transformer output gain. S2. Based on the control logic of the primary winding and the secondary winding of the transformer, the output gain of the transformer is divided. S3. Adjust the calculation formula for output voltage gain to obtain a simplified calculation formula for output voltage gain; S4. Analyze the output gain range of the divided transformers respectively, select the parameter value in the output voltage gain formula according to the output voltage range, and obtain the frequency variation range under different output gain ranges. S5. Based on the modification and analysis of the transformer, the specific control flow for charging of the improved LLC topology circuit is obtained. S501. After starting the entire system, the operator sets the intensity level through the host computer software and transmits the intensity value L to the lower-level computer via communication. The lower-level computer MCU obtains the target charging voltage value based on the intensity-charging voltage table pre-stored in its memory. ; S502, lower-level MCU for target charging voltage value Make a judgment within four threshold ranges. , , and Select from the options and determine the target charging voltage value. After determining the specific threshold range, the switch... , After the MCU completes the output gain selection switch switching, it closes the output charging control switch Kc and enters the control sequence for starting charging. S503, First, the pulse capacitor voltage is charged to the specified voltage value via soft start. After the soft start is completed, the pulse capacitor voltage is charged to the target voltage value using a constant current followed by a constant power method. ; S504, When charged to the target voltage value After the power supply stops working, disconnect the charging control switch. ; After the S505 pulse capacitor discharges to the magnetic coil, the high-voltage power supply repeats the above charging process according to the host computer settings, and so on; when the target voltage... If the error is not within these four threshold ranges, the lower-level MCU will directly return the error to the upper-level MCU.

2. The LLC topology control method for ultra-wide output voltage of a magnetic stimulator according to claim 1, characterized in that: In S1, the primary winding and secondary winding of the transformer are modified as follows: Suppose that the primary winding of the transformer has terminals C and B, and a center tap A is drawn from the middle. The number of turns between C and A is... The number of turns between CB is By switch Switching between connecting winding node A or B to the resonant cavity changes the turns ratio between the secondary and primary sides of the transformer, thereby altering the transformer's output gain range. The two windings on the secondary side of the transformer are switched. , and By controlling the series or parallel connection of the rectified voltages of the two output windings, the output voltage gain range is expanded to twice its original value.

3. The LLC topology control method for ultra-wide output voltage of a magnetic stimulator according to claim 2, characterized in that: In S2, the output gain of the transformer is divided according to the control logic of the primary winding and the secondary winding of the transformer. Assume the maximum range of the output voltage on the high-voltage power supply is The output power is The maximum output current is The input bus voltage is The resonant inductance is The resonant capacitance is The magnetizing inductance between the primary windings CB of the transformer is The number of turns between the primary winding CB of the transformer is The number of turns between CA on the primary side of the transformer is ; From the known circuit parameters above, we can obtain: the magnetizing inductance between CA. for ， resonant frequency for ， The ratio between the magnetizing inductance and the resonant inductance of the primary winding CB of the transformer for ， The ratio between the magnetizing inductance and the resonant inductance of the primary winding CA of the transformer for ， By combining the control logic of the primary and secondary side switches of the transformer, four different gain range combination modes can be formed to adjust the output voltage. It is divided into 4 corresponding intervals, namely: when Connect to B, disconnect ,closure and At that time, the output voltage range is ; when Connect to A, disconnect ,closure and At that time, the output voltage range is ; when Join to B, close ,disconnect and At that time, the output voltage range is ; when Join to A, close ,disconnect and At that time, the output voltage range is ].

4. The LLC topology control method for ultra-wide output voltage of a magnetic stimulator according to claim 3, characterized in that: In S3, for the LLC topology, the voltage gain of the LLC resonant converter is analyzed using the fundamental component analysis method. The output voltage gain formula can be simplified to: ； in the formula For switching frequency, The resonant frequency, For LLC output current, The input bus voltage of the LLC is denoted by m, where m is the output series coefficient, and m is the ratio of the magnetizing inductance to the resonant inductance. Characteristic impedance The turns ratio of the primary winding to the secondary winding of the transformer , This refers to the number of turns in the primary winding of the transformer. This refers to the number of turns in the secondary winding of the transformer. For transformer magnetizing inductance, It is a resonant inductor. It is a resonant capacitor.

5. The LLC topology control method for ultra-wide output voltage of a magnetic stimulator according to claim 4, characterized in that: In S4, the output voltage range is... Analysis was performed when the output voltage range was within... hour, Connect to B, disconnect ,closure and When, in the output voltage gain formula , Magnetizing inductance between the primary windings CB of the transformer The ratio K is The two windings on the secondary side of the transformer are connected in parallel, with an output series coefficient m=1, and the total output voltage... The voltage after rectification is the same as that after rectification of a single secondary output winding; Substitute the values ​​into the simplified formula for output voltage gain and plot the output voltage gain frequency curve; set up For the voltage is Output current is at maximum The curve showing the change of output voltage with frequency; (K, U c1 , / U c1 ) is at voltage U c1 The output current is the maximum load. Divide by the output voltage U c1 The curve showing the change of output voltage with frequency; The voltage versus frequency curve when the resonant network is purely resistive; The output voltage is U c1 The curve of time, The output voltage is The curve at time; Assume the working region is located at the purely resistive boundary line U. res_1st (K,f s Within the sensory region on the right, U c_1st (K,f s U cmin ,I o_max ) and U cmin_set (f s The output voltage U is obtained at the intersection of the inductive regions. cmin The operating frequency is kHz; U c_1st (K,f s U c1 ,P o_max / U c1 ) and U c1_set (f s The output voltage U is obtained at the intersection of the inductive regions. c1 The operating frequency is kHz; when the output voltage is at When it changes, the frequency changes within a range of 100%. kHz~ kHz.

6. The LLC topology control method for ultra-wide output voltage of a magnetic stimulator according to claim 5, characterized in that: In S4, the output voltage range is... Analysis was performed when the output voltage range was within... hour, Connect to A, disconnect ,closure and The number of turns in the primary winding of the transformer is = , and the output voltage range is Compared to the previous method, the number of turns in the primary winding of the transformer is reduced, resulting in a smaller turns ratio N and consequently a larger output voltage gain; the magnetizing inductance of the primary winding of the transformer is also reduced. This makes the ratio between the magnetizing inductance and the resonant inductance of the primary winding of the transformer... As the value decreases, the slope of the frequency gain curve increases, resulting in a larger output voltage gain range within the same frequency range; the output series coefficient m=1; , , Substitute the values ​​into the simplified formula for output voltage gain and plot the gain-frequency curve. set up For voltage is The output current is the maximum load. Divide by output voltage The curve of output voltage versus frequency. For voltage is The output current is the maximum load. Divide by output voltage The curve of output voltage versus frequency. This is the voltage versus frequency curve when the resonant network is purely resistive. The output voltage is The curve of time, The output voltage is The curve at time; Assume the working region is located at the purely resistive boundary. The right-hand sensory region; and The output voltage is obtained at the intersection of the inductive regions. The corresponding operating frequency is kHz; and The output voltage is obtained at the intersection of the inductive regions. The corresponding operating frequency is kHz; when the output voltage is at When it changes, the frequency changes within a range of 100%. kHz~ kHz.

7. The LLC topology control method for an ultra-wide output voltage magnetic stimulator according to claim 6, characterized in that: In S4, the output voltage range is... Analysis was performed when the output voltage range was within... hour, Join to B, close ,disconnect and The number of turns in the primary winding of the transformer is = The two output windings are connected in series after rectification, resulting in an output voltage of... The voltage is twice the rectified voltage of a single output winding, and the output series coefficient m=2. , , Substitute m into the simplified formula for output voltage gain and plot the gain-frequency curve. set up For voltage is The output current is the maximum load. Divide by output voltage The curve of output voltage versus frequency. For voltage is The output current is the maximum load. Divide by output voltage The curve of output voltage versus frequency. This is the voltage versus frequency curve when the resonant network is purely resistive. The output voltage is The curve of time, The output voltage is The curve at time; Assume the working region is located at the purely resistive boundary. The right-hand sensory region; and The output voltage is obtained at the intersection of the inductive regions. The corresponding operating frequency is kHz; and The output voltage is obtained at the intersection of the inductive regions. The corresponding operating frequency is kHz; When the output voltage is When it changes, the frequency changes within a range of 100%. kHz~ kHz.

8. The LLC topology control method for an ultra-wide output voltage magnetic stimulator according to claim 7, characterized in that: In S4, the output voltage range is... ] Analyze the output voltage range when it is within hour, Join to A, close ,disconnect and When the transformer turns ratio N decreases, the magnetizing inductance... The output voltage range is reduced, the two output windings are connected in series, the output series coefficient m=2, and the output voltage range is within... and The control method in the middle increases the output voltage gain range, thus... , , Substitute m into the simplified formula for output voltage gain and plot the gain-frequency curve. set up For voltage is The output current is the maximum load. Divide by output voltage The curve of output voltage versus frequency. For voltage is The output current is the maximum load. Divide by output voltage The curve of output voltage versus frequency. This is the voltage versus frequency curve when the resonant network is purely resistive. The output voltage is The curve of time, The output voltage is The curve at time; Assume the working region is located at the purely resistive boundary. The right-hand sensory region; and The output voltage is obtained at the intersection of the inductive regions. The corresponding operating frequency is kHz; and The output voltage is obtained at the intersection of the inductive regions. The corresponding operating frequency is kHz; when the output voltage is at When the frequency changes, the range of frequency change is: kHz~ kHz; By analyzing the four output voltage gain ranges , , and The calculation and analysis yielded the following results. Eight frequency values ​​are compared and arranged in ascending order. The smallest value is set to... The maximum value is Switching is achieved through the primary and secondary switches of the LLC transformer, within the frequency variation range ( ~ It can achieve an ultra-wide adjustment range of output voltage gain, with a maximum / minimum value of 10 times.

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